Systems and methods for temperature sensing using thermopiles integrated with rigid printed circuit boards

Abstract

The present disclosure relates to systems and methods for temperature sensing using thermopiles integrated with rigid printed circuit boards. Robust estimation of temperature both inside and outside of a device can be achieved using one or more absolute temperature sensors optionally in conjunction with thermopile heat flux sensors. A thermopile temperature sensing system can measure a temperature gradient across two locations within the device to estimate absolute temperature at impractical locations for measurement using absolute temperature sensors. Using a heat flux model associated with the device, the thermopile temperature sensing system can be used to estimate a temperature associated with an object in contact with an outer surface of the device, such as a user's skin temperature. Additionally, the thermopile temperature sensing system can be used to estimate an ambient air temperature. Within the device, temperature measurements from the thermopile temperature sensors can be used to compensate sensor measurements, such as when the accuracy or reliability of a sensor varies with temperature.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 261,659, filed September 24, 2021; U.S. Provisional Application No. 63 / 261,660, filed September 24, 2021; U.S. Provisional Application No. 63 / 261,661, filed September 25, 2021; U.S. Provisional Application No. 17 / 371,820, filed August 18, 2022; U.S. Patent Application No. 17 / 930,041, filed September 6, 2022; U.S. Patent Application No. 17 / 930,053, filed September 6, 2022; and U.S. Patent Application No. 17 / 930,057, filed September 6, 2022, the contents of which are incorporated herein by reference in their entirety for all purposes. Technical Field

[0003] The present invention relates generally to temperature sensing systems and methods, and more specifically to temperature sensing systems and methods using thermopile and / or multiple temperature sensors. Background Technology

[0004] Many types of electronic devices include temperature sensors for measuring temperature. Temperature sensors measure the temperature at a location within the electronic device and provide a signal to the processor on the device corresponding to that temperature measurement. Summary of the Invention

[0005] In some examples, systems and methods for temperature sensing using a thermopile (a collection of thermocouples connected in series) are disclosed. Electronic devices may utilize measurements from multiple sensors within the device, including at least one absolute temperature sensor and at least one other absolute or gradient sensor, such as at least one thermopile temperature sensor, to estimate the temperature inside or outside the device. In some examples, electronic devices use measurements from sensors within the device to estimate the temperature of ambient air (e.g., ambient air temperature). In other examples, electronic devices estimate the temperature (e.g., skin or body temperature) of an object in contact with one or more of its surfaces (e.g., the rear surface, front surface, etc. of the device). In some examples, one or more absolute temperature sensors within the electronic device may be disposed on or otherwise integrated with one or more printed circuit boards (PCBs) (e.g., logic boards, system-in-packages, displays, etc.). In some examples, the thermopile temperature may be configured to measure temperature differences within the device. In some examples, the thermopile may be embedded within or otherwise integrated with a rigid circuit board (e.g., a rigid PCB). In some examples, the thermopile may be embedded within or otherwise integrated with a flexible printed circuit (FPC, also referred to herein as flexible circuitry or flexural circuitry). In some examples, the thermopile may be embedded in or otherwise integrated within a rigid PCB and FPC for other purposes within the electronic device to reduce the additional space required for temperature and / or heat flux sensing. Temperature difference measurements (temperature gradient measurements) from the thermopile temperature sensor can be used to infer heat flux (e.g., through the electronic device) and / or estimate temperatures outside the device (e.g., the air temperature around the device, the surface temperature of an object in contact with the device housing, the body temperature of a user wearing the device, etc.).

[0006] In some examples, temperature sensing systems for electronic devices and methods utilizing multiple temperature sensors are disclosed. The electronic device can utilize measurements from multiple temperature sensors (including, for example, a first absolute temperature sensor at a first location within the device and a second absolute temperature sensor at a second location within the device) to estimate the temperature inside or outside the device (e.g., the temperature of ambient air (e.g., ambient air temperature) or the temperature of an object (e.g., skin or body temperature) in contact with one or more of its surfaces (e.g., the rear surface, front surface, etc. of the device)). In some examples, the first absolute temperature sensor is disposed on or otherwise integrated with a first printed circuit board (PCB) (e.g., a logic board, main logic board, system-in-package component, display, etc.), and the second absolute temperature sensor is disposed on or otherwise integrated with a second PCB different from the first PCB. In some examples, the estimated temperature outside the electronic device is a function of a first temperature measurement from the first absolute temperature sensor, a second temperature measurement from the second absolute temperature sensor, and one or more thermal resistance values ​​corresponding to various locations or regions inside and / or outside the device. In some examples, electronic devices utilize measurements from multiple temperature sensors, including, for example, at least two temperature sensors (e.g., 2, 3, or 4 temperature sensors) to measure and / or estimate the ambient temperature. Attached Figure Description

[0007] Figures 1A to 1G Exemplary systems with heat flux and / or temperature sensors configured to measure or estimate the temperature inside and / or outside the system are shown according to some examples of this disclosure.

[0008] Figure 2 A block diagram of an exemplary electronic device including a temperature sensing system according to some examples of this disclosure is shown.

[0009] Figure 3 A schematic diagram of an exemplary configuration of a thermopile device and thermopile measurement circuit according to some examples of this disclosure is shown.

[0010] Figure 4A A cross-sectional side view of an exemplary electronic device comprising one or more printed circuit boards and temperature sensing circuitry, according to some examples of this disclosure, is shown.

[0011] Figure 4B A schematic diagram of an exemplary configuration including multiple thermopile devices according to some examples of this disclosure is shown.

[0012] Figure 5A and Figure 5BA simplified schematic diagram of the heat flux model of an electronic device relative to a user's body, according to some examples of this disclosure, is shown.

[0013] Figure 6A A cross-sectional side view of an exemplary electronic device having temperature sensing circuitry and / or heat flux sensing circuitry integrated with a printed circuit board is shown, according to some examples of this disclosure.

[0014] Figure 6B An exploded view of a portion of an exemplary electronic device comprising one or more printed circuit boards and an integrated thermopile, according to some examples of this disclosure, is shown.

[0015] Figure 7A An exemplary double-layer rigid printed circuit board with an integrated thermopile, according to some examples of the present disclosure, is shown in a cross-sectional side view, along with optional circuit components mounted on the top and / or bottom surfaces of the printed circuit board.

[0016] Figure 7B A plan view of an exemplary rigid printed circuit board with an integrated thermopile, according to some examples of this disclosure, is shown.

[0017] Figure 8 A cross-sectional side view of an exemplary four-layer rigid printed circuit board having an integrated thermopile spanning four layers, according to some examples of this disclosure, is shown.

[0018] Figure 9 A cross-sectional side view of an exemplary four-layer rigid printed circuit board with an integrated thermopile spanning three layers, according to some examples of this disclosure, is shown.

[0019] Figure 10 A cross-sectional side view of an exemplary four-layer rigid printed circuit board having an integrated thermopile spanning two layers is shown, according to some examples of this disclosure.

[0020] Figure 11 A cross-sectional side view of an exemplary electronic device having temperature sensing circuitry and / or heat sensing circuitry integrated with flexible circuitry, according to some examples of this disclosure, is shown.

[0021] Figure 12A A cross-sectional side view of an exemplary flexible circuit having an inner layer for signal propagation and an outer grounding layer for protecting the inner layer, according to some examples of this disclosure, is shown.

[0022] Figure 12B Examples of integrated thermopile technologies according to this disclosure are shown. Figure 12A A cross-sectional side view of an exemplary flexible circuit.

[0023] Figure 13AA cross-sectional side view of an exemplary flexible circuit according to some examples of this disclosure is shown, wherein a first segment uses an inner layer for data signal propagation and a second segment uses an outer layer (or multiple outer layers) for power signal propagation.

[0024] Figure 13B Examples of integrated thermopile technologies according to this disclosure are shown. Figure 13A A cross-sectional side view of an exemplary flexible circuit.

[0025] Figure 14 An exemplary process for estimating the temperature inside and / or outside a device is shown according to some examples of this disclosure.

[0026] Figure 15 Exemplary processes for operating devices for temperature sensing operations according to some examples of this disclosure are shown.

[0027] Figure 16 Another exemplary process is shown, illustrating an operating device according to some examples of this disclosure for use in temperature sensing operations.

[0028] Figure 17 Another exemplary process is shown, illustrating an operating device according to some examples of this disclosure for use in temperature sensing operations.

[0029] Figure 18 A cross-sectional side view of an exemplary electronic device comprising one or more printed circuit boards and temperature sensing circuitry, according to some examples of this disclosure, is shown.

[0030] Figure 19 A simplified schematic diagram of the heat flux model of an electronic device relative to a user's body, according to some examples of this disclosure, is shown. Detailed Implementation

[0031] The accompanying drawings, which form part of the following description of the examples and illustrate specific examples of optional implementations by way of example, will be referenced in the description. It should be understood that other examples and structural changes may be optionally used without departing from the scope of the disclosed examples.

[0032] This relates to systems and methods for temperature sensing using a thermopile (a collection of thermocouples connected in series). Electronic devices may utilize measurements from multiple sensors within the device, including at least one absolute temperature sensor and at least one other absolute or gradient sensor, such as at least one thermopile temperature sensor, to estimate the temperature inside or outside the device. In some examples, the electronic device uses measurements from sensors within the device to estimate the temperature of the surrounding air (e.g., ambient air temperature). In other examples, the electronic device estimates the temperature (e.g., skin or body temperature) of an object in contact with one or more of its surfaces (e.g., the rear surface, front surface, etc. of the device). In some examples, one or more absolute temperature sensors within the electronic device may be disposed on or otherwise integrated with one or more printed circuit boards (PCBs) (e.g., logic boards, system-in-packages, displays, etc.). In some examples, the thermopile temperature sensor may be configured to measure temperature differences within the device. In some examples, the thermopile may be embedded within or otherwise integrated with a rigid circuit board (e.g., a rigid PCB). In some examples, the thermopile may be embedded within or otherwise integrated with a flexible printed circuit (FPC, also referred to herein as flexible circuitry or flexural circuitry). In some examples, the thermopile may be embedded in or otherwise integrated within a rigid PCB and FPC for other purposes within the electronic device to reduce the additional space required for temperature and / or heat flux sensing. Temperature difference measurements (temperature gradient measurements) from the thermopile temperature sensor can be used to infer heat flux (e.g., through the electronic device) and / or estimate temperatures outside the device (e.g., the air temperature around the device, the surface temperature of an object in contact with the device housing, the body temperature of a user wearing the device, etc.).

[0033] This also relates to temperature sensing systems for electronic devices and methods utilizing multiple temperature sensors. Electronic devices can utilize measurements from multiple temperature sensors (including, for example, a first absolute temperature sensor at a first location within the device and a second absolute temperature sensor at a second location within the device) to estimate the temperature inside or outside the device (e.g., the temperature of ambient air (e.g., ambient air temperature) or the temperature of an object in contact with one or more of its surfaces (e.g., the rear surface, front surface, etc. of the device) using measurements from the temperature sensors within the device (optionally in addition to thermal resistance values ​​at various locations inside and / or outside the device)). In some examples, the first absolute temperature sensor is disposed on or otherwise integrated with a first printed circuit board (PCB) (e.g., a logic board, main logic board, system-in-package component, display, etc.), and the second absolute temperature sensor is disposed on or otherwise integrated with a second PCB, different from the first PCB. In some examples, the estimated temperature outside the electronic device is a function of a first temperature measurement from the first absolute temperature sensor, a second temperature measurement from the second absolute temperature sensor, and one or more thermal resistance values ​​corresponding to various locations or regions inside and / or outside the device. In some examples, electronic devices utilize measurements from multiple temperature sensors, including, for example, at least two temperature sensors (e.g., 2, 3, or 4 temperature sensors) to measure and / or estimate the ambient temperature.

[0034] Figures 1A to 1G Exemplary systems with heat flux and / or temperature sensors configured to measure or estimate temperatures within and / or outside the system are illustrated according to some examples of this disclosure. As described herein, a thermopile temperature sensor measures a temperature difference (temperature gradient measurement) corresponding to a temperature difference or gradient between two locations within an electronic device. In some examples, systems equipped with thermopile temperature sensors use temperature gradient measurements to estimate heat flux within the device. In some examples, systems described herein may use measurements from thermopile temperature sensors to estimate external temperatures (e.g., ambient air temperature, skin temperature, etc.).

[0035] Figure 1A An exemplary mobile phone 136 is shown, which includes a touchscreen 124 and may include a thermopile temperature sensing system according to some examples of the present disclosure. Figure 1B An exemplary digital media player 140 is shown, which includes a touchscreen 126 and may include a thermopile temperature sensing system according to some examples of the present disclosure. Figure 1C An exemplary personal computer 144 is shown, which includes a touchscreen 128 and a touchpad 146 and may include a thermopile temperature sensing system according to some examples of the present disclosure. Figure 1D An exemplary tablet computing device 148 is illustrated, which includes a touchscreen 130 and may include a thermopile temperature sensing system according to some examples of this disclosure. In some examples, the thermopile temperature sensing system within a mobile phone 136, a digital media player 140, a personal computer 144, or the tablet computing device 148 may be used to measure the temperature associated with touchscreens 124, 126, 128, or 130, or the temperature associated with touchpad 146 (e.g., temperature within these devices, temperature outside these devices, temperature of surfaces that touch or are in contact with the touchscreen or touchpad of these devices, etc.).

[0036] Figure 1E An exemplary wearable device 150 (e.g., a watch) is illustrated, which includes a touchscreen 152 and may include a thermopile temperature sensing system according to some examples of this disclosure. In some examples, the thermopile temperature sensing system within the wearable device 150 may be configured to measure the temperature associated with the touchscreen 152. The wearable device 150 may be attached to a user via a strip 154 ​​or any other suitable fastener. Figure 1FAnother exemplary wearable device 160 (or alternatively, a side view of wearable device 150) that may include a thermopile temperature sensing system according to some examples of this disclosure is shown. Wearable device 160 may include a front panel 162, a housing 164, and a rear panel 166. The front panel 162 is sometimes referred to herein as the “front crystal” of wearable device 160, and the rear panel 166 is sometimes referred to herein as the “rear crystal” of wearable device 160. However, it should be understood that the front panel 162 and rear panel 166 generally refer to a substrate such as glass, plastic, or crystal. For example, the front panel 162 and rear panel 166 (also referred to as the rear face) may protect the internal components of wearable device 160 but also allow optical transmission from a display screen (e.g., a touchscreen) and / or optical sensors. In some examples, the thermopile temperature sensing system within wearable device 160 may be used to measure the temperature associated with a touchscreen located at the front panel 162. In such examples, the thermopile temperature sensing system may be configured to measure the temperature at a location or region 163 within the wearable device 160 (e.g., optionally closer to the front 162 than the location of an absolute temperature sensor). Alternatively or additionally, the thermopile temperature sensing system may be used to estimate temperatures outside the wearable device 160, such as the temperature of the air in contact with the front 162, or the temperature of other objects that are at least partially in contact with or overlap with the front 162. In some examples, the thermopile temperature sensing system within the wearable device 160 may be used to measure the temperature associated with an optical system located at the rear 166. In such examples, the thermopile temperature sensing system may be configured to measure the temperature at a location or region 165 within the wearable device 160 (e.g., optionally closer to the rear 166 than the location of an absolute temperature sensor). Alternatively or additionally, the thermopile temperature sensing system may be used to estimate temperatures outside the wearable device 160, such as the temperature of the air in contact with the rear 166, or the temperature of other objects that are at least partially in contact with or overlap with the rear 166 (e.g., skin temperature at the wrist). Finally, the thermopile temperature sensing system can be used to estimate the temperature at any location within the wearable device 160, as well as the temperature of objects outside the wearable device 160 (e.g., the air surrounding the wearable device 160, or objects that are at least partially in contact with the front 162, the back 166, or the housing 164).

[0037] Figure 1GAnother exemplary wearable device, an in-ear headphone 170, which may include a thermopile temperature sensing system, is shown as an example of some examples according to this disclosure. In some examples, the thermopile temperature sensing system within the in-ear headphone 170 is used to measure the temperature of components within the in-ear headphone 170, such as the temperature associated with circuitry within the earbud 172 or protrusion 174. Alternatively or additionally, the thermopile temperature sensing system may be used to estimate temperatures outside the in-ear headphone 170, such as the temperature of the air in contact with the earbud 172 or protrusion 174, and the temperature of other objects (e.g., ear / body temperature) that are at least partially in contact with or overlap with the earbud 172 or protrusion 174.

[0038] It should be understood that Figures 1A to 1G The exemplary device shown is provided by way of example, and other types of devices may include thermopile temperature sensing systems for detecting temperatures inside or outside the device. For example, a device may include one worn on or placed in contact with a user's face, head, or fingers (or at another location on the user's body). Devices may include over-ear headphones, glasses, headbands, chest straps, wristbands, rings, etc. For example, glasses worn on a user's face may include a thermopile temperature system to estimate the skin temperature of the user's temples, forehead, or nose, and other possible locations. In some examples, glasses may include one or more absolute temperature sensors and one or more thermopiles for temperature measurement, terminating at or near the location of interest (e.g., one thermopile may be used to estimate the temperature at the left temple and a second thermopile may be used to estimate the temperature at the right temple). Similarly, headbands, chest straps, or rings may include one or more absolute temperature sensors and / or thermopiles to measure skin temperature at locations in contact with the user's body. In some examples, the thermopile temperature sensing system can be used in thermostat devices (e.g., wall-mounted thermostats) or integrated into devices to add thermostat capabilities (e.g., integrating the thermopile temperature sensing system into computers, tablets, media players, smartphones, smart speakers, etc.). Additionally, although... Figures 1A to 1G Some of the devices shown explicitly refer to touchscreens, but it should be understood that the thermopile temperature sensing system described herein does not require a touchscreen.

[0039] As described herein, the thermopile temperature sensing system can be incorporated into the system (e.g., Figures 1A to 1G(As shown) to add internal and / or external temperature sensing capabilities to electronic devices. Specifically, the use of thermopile as described herein enables more accurate estimations because thermopile reduces the influence of thermal interference sources (e.g., heat sources within the device, such as heat-generating components within the device) and also reduces the overall drift or other errors in temperature estimation (e.g., temperature sensor processes, voltage and / or temperature variations, effects from thermal interference sources, etc.). For example, a thermopile can be considered a dual-ended (or dual-sided) device whose output corresponds to a temperature difference or gradient measurement corresponding to the temperature difference between a first end (or side) of the thermopile and a second end (or side) of the thermopile. Thus, thermopile temperature sensing systems can be configured such that they measure the temperature gradient or temperature difference between an inner surface of the device and another location within the device. Therefore, the placement of an absolute temperature sensor can be separated from the location or area of ​​temperature measurement. Instead, an absolute temperature sensor can be placed in a first location, and the thermopile can be used to estimate the temperature at a second, different location. Thus, absolute temperature sensors can be integrated into devices remote from temperature interference sources and / or provide flexibility for integrating temperature sensors at locations remote from the location or area of ​​interest. Specifically, the thermopile may have a first end coupled to a first location within the device (e.g., near an absolute temperature sensor), and a second end coupled to a second location within the device (e.g., at a location or region of interest). Based on temperature gradient measurements of such a thermopile, the temperature at the second location at the second end of the thermopile can be estimated. Furthermore, using both an absolute temperature sensor and a thermopile temperature sensor to measure heat flux introduces drift or other errors from one absolute temperature sensor, rather than the drift or other errors from both, compared to using a pair of absolute temperature sensors for heat flux measurement. Moreover, integrating a thermopile into an electronic device can provide temperature estimation at locations where the integration of the device's absolute temperature sensor may be difficult or impossible due to space constraints (especially in devices where circuitry can be densely packed and additional sensing devices cannot be easily accommodated).

[0040] Furthermore, the temperature of an object (e.g., air, a user, etc.) can be estimated at a second location outside the device, relative to a corresponding second location inside the device. In some examples, the thermopile temperature sensing system continuously estimates the external temperature during device operation. For example, a system including the thermopile temperature sensing system described herein can be used to measure and / or track a user's body temperature (when authorized by the user). Specifically, wearable electronic devices that are close to a user's body throughout the day and / or at night can provide seamless measurement of body temperature. In some examples, the type of body temperature estimation can vary depending on the usage conditions (such as the time of day or the user's physiological characteristics). For example, when a user's blood vessels are constricted (e.g., limbs and extremities receive less blood flow), a temperature measurement of the user's skin using a wrist-worn electronic device at the wrist may not accurately reflect the user's core body temperature. In some examples, wearable electronic devices worn on a user's wrist (or other limbs or extremities) can be used to estimate physiological temperature values ​​at night when the user is less likely to experience blood vessel constriction. Other wearable electronic devices that can be worn around the chest, on the head, above the eyes, or even positioned within openings in the body can be used to estimate physiological temperature values ​​at any time. In some examples, when a user may be in a state of vasodilation (e.g., at night, such as when the user is asleep), the back of the wearable electronic device can be used to estimate body temperature (e.g., by estimating wrist temperature), but the user can use the front of the electronic device to measure temperatures in body areas that are different from or closer to core body temperature, so that measurements can be taken even during periods of vasoconstriction. For example, a user can bring the front of the wearable device into contact with their forehead to measure core body temperature.

[0041] Figure 2 Block diagrams of computing systems including temperature sensing systems of exemplary electronic devices according to some examples of this disclosure are shown. Although primarily described herein as wearable devices, the computing system may alternatively be implemented partially or entirely in non-wearable devices. For example, the sensors and / or processing described herein may be implemented partially or entirely in mobile phones, media players, tablet computers, personal computers, servers, etc. In some examples, optical sensors (e.g., light emitters and photodetectors) and / or temperature sensors (e.g., absolute temperature sensors or heat flux sensors) may be implemented in wearable devices (e.g., wristwatches), and processing of optical and / or temperature data may be performed in non-wearable devices (e.g., mobile phones). In some examples, such as temperature sensors may be implemented in wearable devices, and data processing may be performed in non-wearable devices. Processing and / or storing optical and / or temperature data in a separate device can enable devices including physiological sensors (e.g., wristwatches) to be space and power efficient (which can be an important feature of portable / wearable devices).

[0042] The computing system 200 can correspond to the above. Figures 1A to 1G The illustrated mobile phone 136, media player 140, personal computer 144, tablet computer 148, wearable device 150, wearable device 160, or in-ear headset 170 (or may be implemented in other wearable or non-wearable electronic devices). The computing system 200 may include a processor 210 (or more than one processor) programmed (configured) to execute instructions and perform operations associated with the computing system 200. For example, using instructions retrieved from program storage device 202, processor 210 may control the reception and manipulation of input and output data between components of the computing system 200. Processor 210 may be a single-chip processor (e.g., an application-specific integrated circuit) or may be implemented using multiple components / circuits. For example, Figure 2 The processor 210 is shown to include a relatively low-power processor 211-1 and a relatively high-power processor 211-2, as described in more detail herein.

[0043] In some examples, processor 210, together with an operating system, is operable to execute computer code and generate and / or use data. The computer code and data may reside within a program storage device 202 operatively coupled to processor 210. Program storage device 202 typically provides a location for holding data used by computing system 200. Program storage device 202 can be any non-transitory computer-readable storage medium. By way of example, program storage device 202 may include read-only memory (ROM), random access memory (RAM), hard disk drive, etc. Computer code and data may also reside on removable storage media and be loaded or mounted onto computing system 200 when needed. Removable storage media include, for example, CD-ROM, DVD-ROM, Universal Serial Bus (USB), Secure Digital (SD), Compact Flash (CF), memory sticks, Multimedia Card (MMC), and / or network components.

[0044] As described herein, in some examples, host processor 210 may represent multiple processors, such as a lower-power processor 211-1 and a higher-power processor 211-2. Lower-power processor 211-1 and higher-power processor 211-2 may represent separate processing chips, each with independent timing and power requirements. For example, lower-power processor 211-1 may operate using a first clock signal and at a first power level, allowing processor 211-1 to remain operational (“on”) in most or all operating modes of system 200 (e.g., sleep mode, wake-up mode, idle mode, etc.). In contrast, higher-power processor 211-2 may operate using a second clock signal (e.g., a high-frequency clock) different from the first clock signal and at a second power level higher than the first power level. Due to the higher power requirements of higher-power processor 211-2, host processor 210 (e.g., the operating system on processor 210) may selectively disable higher-power processor 211-2, power it down, or otherwise limit its power consumption during certain operating modes of system 200 (e.g., power-saving mode, sleep mode, etc.). In some examples, as described herein, the higher power processor 211-1 may be powered down or otherwise limited in its power consumption to achieve temperature measurement without errors introduced by the power dissipation of the higher power processor 211-1.

[0045] The lower-power processor 211-1 and / or the higher-power processor can connect to various sensor interfaces of the system 200, including touch sensor panels and / or touchscreens 220 (via touch and display controller 216), motion and / or orientation sensors 230, optical sensors 211 (via optical sensor controller 212), and temperature sensors 250 (via temperature sensor controller 240). In some examples, the lower-power processor 211-1 can operate in sleep or power-saving mode while the higher-power processor 211-2 is powered down. In some examples, the lower-power processor 211-1 can alter the operating mode of the system 200 or otherwise power up the higher-power processor 211-2 (e.g., when a wake-up condition is detected).

[0046] The computing system 200 may also include power management circuitry 209 and / or power dissipation monitoring circuitry 213. A host processor 210 (e.g., a lower-power processor 211-1 and / or a higher-power processor 211-2) may be coupled to power management circuitry 209 and / or power dissipation monitoring circuitry 213. Power management circuitry 209 may regulate power delivery from a power supply circuit (e.g., a battery or other power source for system 200) to various components of system 200 (e.g., sensors, processors, antennas, displays, etc.). As an example, power management circuitry 209 may interrupt or limit power delivery to components that generate heat within system 200 (e.g., sources of thermal interference), especially during temperature measurements that may be sensitive to heat from such components. Power management circuitry 209 may monitor temperatures within and / or outside the housing of system 200 (e.g., ambient temperature, user skin / core temperature). As an example, power management circuitry 209 can monitor these temperatures to detect unsafe operating conditions of system 200 and can selectively interrupt or limit power delivery to certain heat-generating components to bring system 200 into a safe operating state. In some examples, power management circuitry 209 provides control signals to in-line switches coupled between the system's power supply circuitry and various components of system 200, wherein the control signals determine the amount of current or power that can be delivered to the respective components. As an example, power management circuitry 209 can provide a first control signal to a switch inserted between the battery power supply of system 200 and touchscreen 220, such that the first control signal limits the amount of power or current delivered from the battery power supply to the touchscreen. As another example, power management circuitry 209 can provide a second control signal to a switch inserted between the battery power supply of system 200 and the system's antenna circuitry (not shown), such that the second control signal interrupts power delivery or current flow between the battery power supply and the antenna circuitry.

[0047] Power dissipation monitoring circuit 213 can monitor the power supply circuit (not shown) of system 200 and can regulate power transfer from the power supply circuit to various components of system 200 (e.g., by sending commands to power management circuit 209). In some examples, power dissipation monitoring circuit 213 includes a sensor coupled to the power supply circuit (e.g., battery) of system 200. The sensor can measure the power drawn by components of system 200 from the power supply circuit (e.g., battery of system 200). In some examples, the power draw of system components can be estimated based on the current draw from the power supply circuit. In some examples, the power drawn can be estimated based on the device (e.g., estimated current drawn from the battery). In some examples, the power drawn can be estimated on a per-component basis for some (e.g., known sources of thermal interference) or all of the components. In some examples, power dissipation monitoring circuit 213 includes at least one resistor (e.g., with a resistance greater than 10 MOhm, 20 MOhm, etc.) coupled between the power supply circuit or battery of system 200 and the power-drawing components of system 200. The current through a resistor can be measured by determining the voltage across the resistor (e.g., periodically or in response to a trigger) and converting the voltage to resistance (e.g., using Ohm's law).

[0048] In some examples, computing system 200 (e.g., processor 210, power management circuitry 209, and / or power dissipation monitoring circuitry 213) may include a power dissipation model that correlates current / power draw from the power supply or battery of system 200 with temperature or heat dissipation within the device. Additionally or alternatively, computing system 200 may include models for estimating power consumption and / or resulting temperature variations of different components in different operating modes of system 200 (e.g., power consumption of touchscreen 220 in idle mode, low brightness mode, high brightness mode, etc.). The impact of power consumption of certain components or thermal disturbances in system 200 can be determined using laboratory characterization of the components (e.g., rise time, fall time, and amplitude measured for each thermal disturbance at various corresponding power levels). Therefore, computing system 200 may dynamically model the temperature within system 200 based on the power dissipation model and one or more current / power draw measurements at the system's power supply circuitry or battery. In some examples, power management circuitry 209 may limit or interrupt power delivery to certain components based on information from power dissipation monitoring circuitry 213, such as during measurement intervals associated with temperature sensor 250 (e.g., intervals in which sensor data is collected from temperature sensor 250). For example, when a power dissipation model indicates that the amount of power drawn by components of system 200 corresponds to a temperature within the device that is outside the range required for accurate and / or reliable operation of temperature sensor 250, power management circuitry 209 limits or interrupts power to components of system 200 such that the total power drawn by the components is reduced to a level corresponding to the temperature within the range required for accurate and / or reliable operation of temperature sensor 250. In some examples, power dissipation monitoring circuitry 213 and / or power management circuitry may cause host processor 210 to delay the execution of certain functions or operations to limit or interrupt power to components of system 200. As an example, the host processor 210 may defer (or modify operation to reduce power consumption) the operation of other components involving the touchscreen 220, GPS circuitry (not shown), wireless communication chip (not shown), antenna (not shown), or system 200 that could be sources of thermal interference, until after a measurement interval associated with the temperature sensor 250 (e.g., an interval during which one or more components receive less power).

[0049] Additionally or alternatively, component characterization (e.g., rise time, fall time, and amplitude measured for each thermal disturbance source at various corresponding power levels) can be used for temperature compensation. For example, host processor 210 can use a temperature compensation model to adjust sensor measurements or sensor data based on the temperature within the device or the temperature contribution of thermal disturbance sources (e.g., heat-generating components of system 200). As an example, the power draw of components of system 200 can be measured by power dissipation monitoring circuitry 213. The measured power draw can be used to correct for heat from thermal disturbance sources within the device. In some examples, compensation can be applied when the power draw corresponds to temperature variations outside the range required for accurate and / or reliable operation of temperature sensor 250. Thus, (e.g., temperature sensor controller 240) can use a temperature compensation model (e.g., corresponding to temperature variations in the power drawn by components) to adjust sensor data from temperature sensor 250 to account for temperature increases within the device caused by thermal disturbance sources.

[0050] The computing system 200 may also include one or more input / output (I / O) controllers operatively coupled to the processor 210. The I / O controllers may be configured to control interaction with one or more I / O devices, such as touch sensor panels, displays, touchscreens, physical buttons, dial pads, slider switches, joysticks, or keyboards. The I / O controllers operate by exchanging data between the processor 210 and the I / O devices that wish to communicate with the processor 210. The I / O devices and the I / O controllers may communicate via a data link. The data link may be unidirectional or bidirectional. In some cases, I / O devices may be connected to the I / O controller via a wireless connection. For example, the data link may correspond to any wired or wireless connection, including but not limited to PS / 2, Universal Serial Bus (USB), FireWire, Thunderbolt, Wireless Direct, IR, RF, Wi-Fi, Bluetooth, etc.

[0051] The computing system 200 may include a temperature sensor controller 240 operatively coupled to a processor 210 and one or more temperature sensors 250. As described herein, in some examples, the temperature sensor controller 240 may be coupled to an optical sensor controller 212. The temperature sensor 250 may include one or more absolute temperature sensors 254, one or more heat flux sensors 256, and corresponding sensing circuitry 252 (e.g., analog and / or digital circuitry for measuring signals at sensors 254 / 256, providing processing (e.g., amplification, filtering, level shifting), and converting analog signals into digital signals). As an example, the one or more absolute temperature sensors 254 and one or more heat flux sensors 256 may be configured to measure temperatures at various locations within the system 200, including at least one location or area within the wearable device that differs from the location or area of ​​the system 200 where the absolute temperature sensors are located. These temperature and / or heat flux measurements may be used to measure the temperature characteristics of the device in various operating modes (e.g., to estimate when the temperature inside the device approaches unsafe or unsustainable levels), to estimate the ambient temperature outside the device, or to estimate physiological signals associated with the user (e.g., the user's body temperature)). Raw data from measurements by absolute temperature sensor 254, heat flux sensor 256, and sensing circuitry 252 can be transferred to processor 210 (via temperature sensor controller 240), and processor 210 can perform the signal processing described herein to estimate internal or external temperatures and / or estimate physiological signals (e.g., body temperature associated with a user). Processor 210 and / or temperature sensor controller 240 can operate temperature sensor 250 to measure temperature values ​​associated with system 200 and estimate temperature values ​​associated with the environment outside the system. In some examples, temperature sensor controller 240 may include signal processor 242 to sample, filter, and / or convert (from analog to digital) signals generated by various temperature sensors 250, which may be located at different locations within the housing of system 200. Signal processor 242 may be digital signal processing circuitry, such as a digital signal processor (DSP). Analog data measured by temperature sensor 250 can be converted into digital data by analog-to-digital converter (ADC). In some examples, digital data from the temperature sensor may be stored for processing in a buffer (e.g., FIFO) or other volatile or non-volatile memory (not shown) within the temperature sensor controller 240. In some examples, data from the temperature sensor is used as input to a thermal model of the device and to estimate the temperature outside the enclosure of system 200 (e.g., the temperature of an object or user in contact with a part of the device, or the ambient temperature). In some examples, the processor 210 and / or the temperature sensor controller 240 may store raw data and / or processed information in memory (e.g., ROM or RAM) for historical tracking or future diagnostic purposes.

[0052] To accurately model the environment outside system 200, in some examples, absolute temperature sensor 254 and heat flux sensor 256 may be used in combination. In some examples, temperature sensor controller 240 may use measurements from multiple individual absolute temperature sensors 254 located at well-defined locations ideally within the housing of system 200 to estimate the heat flux through the device (e.g., without using one or more dedicated heat flux sensors). In some examples, absolute temperature sensors may include negative temperature coefficient (NTC) temperature sensors, resistance temperature detectors (RTDs), or diode-based temperature sensors. Heat flux sensor 256 (such as a thermopile temperature sensor) includes multiple thermocouples coupled in series. Each thermocouple may include two (or more) different conductive materials characterized by different corresponding Seebeck coefficients or otherwise associated with different corresponding Seebeck coefficients. A first end of heat flux sensor 256 may include a first set of contacts between two different conductive materials, and a second end of heat flux sensor 256 may include a second set of contacts between two different conductive materials. When the two ends of the heat flux sensor 256 are positionable at corresponding first and second locations within the system 200, the heat flux sensor 256 generates a voltage signal proportional to the temperature gradient or temperature difference between the first and second locations within the system 200. When one end of the heat flux sensor 256 is positioned or mechanically coupled to a location or area within the housing of the system 200, the temperature sensor controller 240 can use the temperature gradient generated by the heat flux sensor to estimate the temperature of an object in contact with an outer surface location of the system 200, which may correspond to a location where one end of the heat flux sensor 256 can be positioned inside the device.

[0053] The computing system 200 may include an optical sensor controller 212 operatively coupled to a processor 210 and one or more optical sensors 211. The optical sensors may include a light emitter 204, a light detector 206, and corresponding sensing circuitry 208 (e.g., analog circuitry for driving signals at the emitter and measuring the detector, providing processing (e.g., amplification, filtering), and converting analog signals into digital signals). As an example, the light emitter 204 and light detector 206 may be configured to generate light and emit it into a user's skin and detect reflected light (e.g., reflection and / or scattering) to measure physiological signals (e.g., vascular volumetric imaging or PPG signals). Absorption and / or return of light at different wavelengths may also be used to determine user characteristics (e.g., oxygen saturation, heart rate) and / or the contact status between the light emitter 204 / light detector 206 and the user's skin. Raw data from measurements taken from light emitter 204, photodetector 206, and sensing circuitry 208 can be transferred to processor 210, which can perform the signal processing described herein to estimate user characteristics (e.g., oxygen saturation, heart rate, etc.) based on physiological signals. Processor 210 and / or optical sensor controller 212 can operate light emitter 204, photodetector 206, and / or sensing circuitry 208 to measure data from the optical sensors. In some examples, optical sensor controller 212 may include timing generation for light emitter 204, photodetector 206, and / or signal processor 214 to sample, filter, and / or convert (from analog to digital) signals measured for light at different wavelengths. Optical sensor controller 212 can process data from signal processor 214 and report outputs (e.g., PPG signal, relative modulation ratio, perfusion index, heart rate, wrist / extra-wrist status, etc.) to processor 210. Signal processor 214 may be digital signal processing circuitry, such as a digital signal processor (DSP). Analog data measured by optical sensor 211 can be converted into digital data by an analog-to-digital converter (ADC), and the digital data from physiological signals can be stored for processing in a buffer (e.g., FIFO) or other volatile or non-volatile memory (not shown) in optical sensor controller 212. In some examples, for instance, some light emitters and / or photodetectors can be activated, while others can be deactivated (by power management circuitry 209) to save power, for example, or for time multiplexing (e.g., to avoid interference between channels). In some examples, processor 210 and / or optical sensor controller 212 can store raw data and / or processed information in memory (e.g., ROM or RAM) for historical tracking or for future diagnostic purposes.

[0054] In some examples, some light emitters and / or light detectors have operating characteristics that vary based on the temperature of the light emitter and / or light detector. As an example, some light emitters can output light at a wavelength that varies based on the temperature of the light emitter. In some examples, optical sensor controller 212 and / or processor 210 (higher power processors 211-2 and / or lower power processors 211-1) can receive temperature information associated with the light emitter (e.g., from temperature sensor controller 240) and adjust the wavelength of the optical sensor and / or the processing of signals associated with the light emitter and / or corresponding light detector based on the received temperature information. For example, estimations of physiological characteristics (e.g., oxygen saturation, heart rate) can be sensitive to the wavelength of the light used to measure the optical signal. In some examples, optical sensor controller 212 and / or processor 210 can use the received temperature information to estimate the wavelength of the light generated by the optical sensor and compensate for the estimation of physiological characteristics based on the estimated wavelength of the light.

[0055] The computing system 200 may also include one or more motion and / or orientation sensors 230, such as accelerometers, gyroscopes, inertial measurement units (IMUs), etc. In some examples, the motion and / or orientation sensors 230 may include multi-channel accelerometers (e.g., 3-axis accelerometers).

[0056] In some examples, the computing system 200 may also include a touch and display controller 216 operatively coupled to the processor 210 and the touchscreen 220. For example, the touchscreen 220 may be configured to display visual output in a graphical user interface (GUI). The visual output may include text, graphics, video, and any combination thereof. In some examples, the visual output may include a textual or graphical representation of a physiological signal (e.g., a PPG waveform) or characteristics of a physiological signal (e.g., oxygen saturation, heart rate, etc.). The touchscreen may be any type of display, including liquid crystal displays (LCDs), light-emitting polymer displays (LPDs), electroluminescent displays (ELDs), field emission displays (FEDs), light-emitting diode displays (LEDs), organic light-emitting diode displays (OLEDs), etc. The processor 210 may send raw display data to the touch and display controller 216, and the touch and display controller 216 may send signals to the touchscreen 220. The data may include voltage levels for multiple display pixels in the touchscreen 220 to project an image. In some examples, the processor 210 may be configured to process raw data and send signals directly to the touchscreen 220. The touch and display controller 216 can also detect and track touch or proximity touches (and any movement or release of the touch) on the touchscreen 220. For example, the touch processor 218 can process data representing touch or proximity touches on the touchscreen 220 (e.g., location and magnitude) and recognize touch or proximity gestures (e.g., tap, double tap, swipe, clamp, reverse clamp, etc.). The processor 210 can translate the detected touch input / gesture into an interaction with a graphical object (such as one or more user interface objects) displayed on the touchscreen 220, or perform other functions (e.g., to initiate device wake-up or power on one or more components).

[0057] In some examples, touch and display controller 216 may be configured to send raw touch data to processor 210, and processor 210 may process the raw touch data. In some examples, touch and display controller 216 may process the raw touch data itself (e.g., in touch processor 218). The processed touch data (touch input) may be transferred from touch processor 218 to processor 210 to perform a function corresponding to the touch input. In some examples, a separate touch sensor panel and display may be used instead of a touchscreen, via corresponding touch controller and display controller.

[0058] In some examples, touch sensing of the touchscreen 220 may be provided by capacitive touch sensing circuitry (e.g., based on mutual capacitance and / or self-capacitance). For example, the touchscreen 220 may include touch electrodes arranged as a matrix of small, individual conductive material plates or as drive lines and sensing lines, or arranged in another pattern. The electrodes may be formed of a transparent conductive medium (such as ITO or ATO), but other partially or completely transparent and opaque materials (e.g., copper) may also be used. In some examples, the electrodes may be formed of other materials, including conductive polymers, metal meshes, graphene, nanowires (e.g., silver nanowires), or nanotubes (e.g., carbon nanotubes). The electrodes may be configured for mutual capacitance or self-capacitance sensing, or a combination of mutual capacitance and self-capacitance sensing. For example, in one operating mode, the electrodes may be configured to sense the mutual capacitance between the electrodes; in different operating modes, the electrodes may be configured to sense the self-capacitance of the electrodes. During self-capacitance operation, an AC waveform may be used to excite the touch electrodes, and the self-capacitance of the touch electrodes to ground may be measured. The self-capacitance of the touch electrodes to ground may change (e.g., increase) when an object approaches the touch electrodes. This change in the self-capacitance of the touch electrodes can be detected and measured by a touch sensing system to determine the position of one or more objects when one or more objects touch or approach the touchscreen without touching it. During mutual capacitance operation, the first touch electrode can be stimulated by an AC waveform, and the mutual capacitance between the first and second touch electrodes can be measured. When an object approaches the overlapping or adjacent area of ​​the first and second touch electrodes, the mutual capacitance between them can change (e.g., decrease). This change in mutual capacitance can be detected and measured by a touch sensing system to determine the position of one or more objects when multiple objects touch or approach the touchscreen. In some examples, some of the electrodes can be configured to sense the mutual capacitance between them, and some of the electrodes can be configured to sense their self-capacitance.

[0059] It should be noted that one or more functions described herein (including estimating the temperature inside or outside an electronic device according to some examples of this disclosure) may be executed by firmware stored in memory (or program storage device 202) and executed by temperature sensor controller 240, optical sensor controller 212, touch and display controller 216, or processor 210. The firmware may also be stored and / or delivered in any non-transitory computer-readable storage medium for use or in combination with an instruction execution system, apparatus, or device, such as a computer-based system, a processor-included system, or other system that can retrieve and execute instructions from and execute instructions from the instruction execution system, apparatus, or device. In the context of this document, "non-transitory computer-readable storage medium" can be any medium (excluding signals) that can contain or store programs for use or in combination with an instruction execution system, apparatus, or device. Computer-readable storage media may include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, portable computer disks (magnetic), random access memory (RAM) (magnetic), read-only memory (ROM) (magnetic), erasable programmable read-only memory (EPROM) (magnetic), portable optical discs such as CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash memory cards, secure digital cards, USB storage devices, memory sticks, etc.

[0060] This firmware can also be propagated in any transmission medium for use or in conjunction with an instruction execution system, apparatus, or device, such as a computer-based system, a processor-based system, or other system capable of retrieving and executing instructions from and with an instruction execution system, apparatus, or device. In the context of this document, "transmission medium" can be any medium through which a program can be transmitted, propagated, or transferred for use or in conjunction with an instruction execution system, apparatus, or device. Transmission media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, or infrared wired or wireless transmission media.

[0061] Figure 3 A schematic diagram illustrating an exemplary configuration of a thermopile device and thermopile measurement circuit according to some examples of this disclosure is shown. The thermopile sensing system includes a thermopile 310 and a thermopile measurement circuit (sensing circuit) 330, which can be accessed by electronic devices (e.g., Figures 1A to 1G This is achieved using the device shown.

[0062] The thermopile 310 may correspond to the heat flux sensor 256, and the sensing circuit 330 may include components from the sensing circuit 252 and / or the signal processor 242. The thermopile 310 may include a collection of thermocouples connected in series, each thermocouple comprising conductive segments of two different conductors. Typically, any two different conductors (or more than two conductors) may be used in the thermopile, provided they have different associated Seebeck coefficients suitable for generating the desired temperature gradient. As an example, conductive path 314 of the thermopile 310 may be formed of a first conductive material such as copper (Cu) having a first Seebeck coefficient, and conductive path 316 of the thermopile 310 may be formed of a second conductive material such as a copper-nickel alloy (CuNi, sometimes simply referred to as "constantan," but the alloy may contain a different material ratio than 55% copper - 45% nickel) having a second Seebeck coefficient different from the first Seebeck coefficient. These specific materials used in conductive paths 314 and 316 are exemplary, and any conductor with suitable different Seebeck coefficients may be used in the thermopile 310. Furthermore, it should be understood that although this article primarily describes the use of two different conductors with two different Seebeck coefficients, thermopile can be implemented using more than two conductors with additional Seebeck coefficients (e.g., three conductors, four conductors, etc.). In some examples, different materials may be chosen to balance the positive and negative Seebeck effects of the two or more conductors used.

[0063] Conductive path 314 may be coupled to conductive path 316 in series at two contacts. As described herein, the two contacts are generally referred to as hot contact 318 and cold contact 312, but it should be understood that, more generally, these two contacts may be referred to as first contact and second contact. As an example, a first path of conductive path 314 may extend from cold contact 312 to hot contact 318, and may be coupled at hot contact 318 to a first path of conductive path 316 (e.g., through via hole 319 or another connector). The first path of conductive path 314 and the first path of conductive path 316 may together form a first thermocouple. The first path of conductive path 316 may then extend from hot contact 318 to cold contact 312, and may be coupled at cold contact 312 to a second path of conductive path 314 (e.g., through via hole 319 or another connector). The second path of conductive path 314 can then extend from cold contact 312 to hot contact 318, and can be coupled at hot contact 318 to the second path of conductive path 316 (e.g., through through hole 319 or another connector). The second paths of conductive path 314 and conductive path 316 together form a second thermocouple that can be coupled in series with the first thermocouple. Conductive paths 314 and 316 can be used in a similar manner to form additional series of thermocouples.

[0064] In some examples, conductive path 314 may be formed on a different layer than conductive path 316 (e.g., in a flexible printed circuit or FPC) and may be coupled to each other using vias 319. For example, as shown, conductive path 314 and conductive path 316 may be formed on different layers (e.g., separated by a dielectric layer). As described herein, in some examples, conductive path 314 and conductive path may be implemented in a flexible printed circuit. In some examples, conductive path 314 and conductive path may be implemented in a rigid printed circuit board. In other examples, conductive path 314 may be formed on the same layer as conductive path 316, spaced apart, and connected using connectors (e.g., connecting conductive path 314 to conductive pattern of conductive path 316). In examples where paths 314 and 316 may be formed on different layers, the corresponding conductive path of conductive path 314 may partially overlap with one or more conductive paths of conductive path 316, and / or the corresponding conductive path of conductive path 316 may partially overlap with one or more conductive paths of conductive path 314 (e.g., as shown in the figure). Figure 3 As shown, the paths partially overlap. For example, based on the example provided above, the first path of conductive path 316 may partially overlap with the first path of conductive path 314 to realize a first via 319 therebetween, and the first path of conductive path 316 may partially overlap with the second path of conductive path 314 (e.g., at opposite junctions) to realize a second via 319 therebetween. Additionally, as described in more detail herein (e.g., relative to...), Figures 6A to 10 In some examples, thermopile can be implemented using vias in a printed circuit board, where the vias have different Seebeck coefficients.

[0065] The thermopile 310 can generate an output voltage at the cold junction 312 between its two terminals 315A and 315B, corresponding to the temperature difference or gradient between the two junctions (e.g., between the hot junction 318 and the cold junction 312), thereby measuring the heat flux through its two ends (e.g., the hot junction and the cold junction) when the thermal resistance is known. Compared to arrangements that estimate heat flux based on the difference between temperature readings from two different absolute temperature sensors 254 whose locations may be constrained within an electronic device (e.g., given space constraints that make temperature sensor integration difficult, and which may be limited to a specific PCB mounted at a distance from the location or area of ​​interest within the device), the thermopile 310 can position its hot junction 318 directly at or closer to the temperature sensing surface (e.g., ...). Figure 1F The location or region (163 / 165) can be improved, which enhances the coupling with the sensing surface of interest and the repeatability of heat flux measurements. Furthermore, because the thermopile 310 directly measures the temperature gradient, drift errors can be doubled by using two absolute temperature sensors, providing more accurate heat flux or temperature gradient measurements.

[0066] The use of thermopile can also simplify manufacturing and increase throughput. For example, an absolute temperature sensor may require extensive characterization and calibration (e.g., during manufacturing) to produce accurate temperature readings within system 200. However, compared to an absolute temperature sensor (especially when used in conjunction with another absolute temperature sensor for heat flux measurement), thermopile 310 may require no factory calibration or may require less factory calibration and characterization to produce accurate readings. Thermopile 310 may have significantly higher accuracy than absolute temperature sensor 254 (e.g., orders of magnitude improvement). As an example, thermopile 310 may be accurate to a temperature difference (ΔT) of + / - 0.01 degrees Celsius, while the factory-calibrated and characterized absolute temperature sensor 254 is accurate to + / - 0.1 degrees Celsius. As described herein, the heat flux sensor 256, including the thermopile 310, can measure the temperature difference between two contacts (e.g., cold contact 312 and hot contact 318), and one of the contacts (e.g., cold contact 312) can be positioned adjacent to and electrically connected to the absolute temperature sensor 254.

[0067] Based on the absolute temperature measurement of the sensor 254 located at the cold junction 312 and the temperature difference or gradient measurement generated by the thermopile 310, the temperature sensor controller 240 can estimate the temperature value at the hot junction 318. Specifically, the temperature at the hot junction 318 can be the temperature measured by the sensor 254 located at the cold junction 312, plus the temperature difference or gradient measurement between the hot junction 318 and the cold junction 312 generated by the thermopile 310. In this way, the thermopile 310 can be positioned such that its hot junction 318 is at a surface or location of interest, and the temperature sensor controller 240 can use the temperature difference / gradient value generated by the thermopile 310 and the absolute temperature sensor 254 located at or near the cold junction 312 to measure the temperature at the location of interest. The advantage of this arrangement over arrangements relying on absolute temperature sensors is that it allows the thermopile to form a thermal junction that is in direct contact with or more closely coupled to a particular device surface (e.g., closer to the front 162 or rear 166 than the absolute temperature sensor) or to components within the device (e.g., a light emitter 204 whose light emission varies with temperature). The thermopile 310 enables temperature measurements at locations of interest that might otherwise be impossible or impractical to collect using an absolute temperature sensor (e.g., because the absolute temperature sensor cannot be mounted or otherwise tightly integrated within the device). As described herein, the thermopile also offers advantages over thermocouples. For example, one advantage of the thermopile can be the relatively high differential voltage across a series of thermocouples, which provides a better signal-to-noise ratio and also offers flexibility in selecting the circuitry used to sense the differential voltage. Another advantage of the thermopile is that the differential voltage can be averaged over the region of the thermopile, rather than measuring a specific location, which smooths out localized temperature anomalies.

[0068] The thermopile 310 may be connected to a sensing circuit 330, which may include a first stage 320, a second stage 322, and an analog-to-digital converter (ADC) 324. The first stage 320 may include an amplifier 321, such as an operational amplifier (op-amp). In some examples, the operational amplifier may have a positive input terminal biased at a specific voltage level (e.g., using a resistor divider between power and ground or between high and low voltages), and a negative input terminal that may be coupled to the output of the op-amp. The output of the operational amplifier may be a bias voltage applied to a first terminal 315A of the thermopile 310 and coupled to the second stage 322 via an input resistor. In some examples, the first stage 320 may be referred to as a bias amplifier because it generates a bias voltage for the thermopile 310 and for the second stage 322. The second stage 322 may include another amplifier 323 (e.g., an op-amp) having an input resistor and a feedback resistor. The positive terminal of the op-amp of the second stage 322 may be connected to a second terminal 315B of the thermopile 310. ADC 324 can be coupled to the outputs of the first stage 320 and the second stage 322. For example, the output of the first stage can be used as a reference voltage and the output of the second stage can be used as the input voltage of the ADC. ADC 324 can be configured to generate a digital value corresponding to the voltage output by thermopile 310 (differential operation by removing the reference bias voltage from the output). In some examples, the second stage 322 can be referred to as a differential amplifier because it amplifies the differential voltage between the two terminals 315A-315B of thermopile 310 (e.g., where the gain of the amplifier can be a function of the feedback resistor). As described above, the voltage output by thermopile 310 (which comprises a plurality of thermocouples connected in series) is optionally formed by conductive paths of metals (e.g., Cu and CuNi) with different Seebeck coefficients, and can be proportional to the temperature difference between cold junction 312 and hot junction 318. The digital conversion of the voltage output from the first stage 320 and the second stage 322 can be based on the voltage generated by the thermopile 310, and can be used by the processing circuit to estimate the temperature at the hot junction 318 based on the absolute temperature sensor measurement at or around the cold junction 312 (e.g., the temperature at the hot junction 318 is the temperature at the cold junction 312 plus the temperature difference between the hot junction 318 and the cold junction 312 generated by the thermopile 310).

[0069] Figure 4A A cross-sectional side view of an exemplary electronic device including one or more printed circuit boards and temperature sensing circuitry, according to some examples of this disclosure, is shown. Wearable device 400 may correspond to... Figure 1E Equipment 150 and / or Figure 1F 160 (or more generally, may correspond to) Figures 1A to 1G(Any of the electronic devices shown). Device 400 may include a housing 410 (e.g., corresponding to strip 154 ​​and housing 164) secured to user 460 via strip 412 or any other suitable fastener. In some examples, device 400 may be secured to user 460 (e.g., exposed skin on the user's body). Device 400 may correspond to a watch, fitness tracker, or any other device (e.g., optionally used to measure physiological signals associated with user 460). Device 400 may be attached to user 460 around the wrist, head, above the eyes, or on any exposed surface of the body suitable for measuring physiological signals associated with the user.

[0070] Multiple printed circuit boards (PCBs) 420, 430, and 440 are shown within housing 410. For example, PCB 420 may be located inside device 400, at the front (sometimes referred to as the "front crystal"). In some examples, PCB 420 may be used to implement a touch sensor panel, display, or touchscreen (e.g., touchscreen 220) disposed below the front. PCB 430 may be located inside device 400, between PCBs 420 and 440. In some examples, PCB 430 may include a host processor 210, a program storage device 202, and optional touch and display controllers 216, optical sensor controllers 212, and / or temperature sensor controllers 240. In some examples, PCB 430 may also include a discrete absolute temperature sensor 432 (e.g., similar to...). Figure 2 The absolute temperature sensor 254 is included. PCB 440 may be located within device 400, at or near rear 450 (sometimes referred to as "rear crystal"), below PCB 430. In some examples, PCB 440 may additionally or alternatively include a discrete absolute temperature sensor 442. In some examples, absolute temperature sensor 442 may be separable from rear 450 via PCB 440, and PCB 440 may be separable from housing 410 (e.g., not in direct contact with housing 410 due to the presence of one or more interlayers or air gaps). For example, PCB 440 may be separable from the inner surface of rear 450, and sometimes a barrier and one or more adhesive layers (not shown) may be positioned between PCB 440 and rear 450. PCB 440 may include an optical sensor 211 configured to emit light and detect light passing through rear 450 (e.g., a light emitter and detector are mounted on the side of PCB 440 opposite to sensor 442). It should be understood that the number of PCBs, the number of temperature sensors, and the placement of the PCBs and... Figure 4AThe component distribution between the PCBs shown is representative and not limiting. For example, fewer or more PCBs can be used, fewer temperature sensors can be used (e.g., absolute temperature sensor 432 or absolute temperature sensor 442 can be omitted), and a device larger than the exemplary one shown (e.g., such as...) can be used. Figure 18 The temperature sensors shown in the figure may be distributed differently across one or more PCBs.

[0071] In some examples, discrete absolute temperature sensors 432 and 442 can be used to calculate the heat flux through the device housing 410. As an example, the temperature difference between the absolute temperature sensors mounted to PCBs 430 and 440 can be determined by subtracting the temperature measured by sensor 442 from the temperature measured by sensor 432. This temperature difference can then be used to calculate the heat flux through the device, and to estimate the temperature outside the device (e.g., ambient air temperature at the back crystal or body temperature at the back crystal 450). However, the accuracy of this arrangement can rely on high thermal resistance between the pair of absolute temperature sensors 432 and 442, and further on the assumption that there are no sources of thermal interference or heat between sensors 432 and 442. Furthermore, due to the distance separating sensors 432 and 442 from the front and rear 450 of device 400, temperature estimates of these surfaces based on sensors 432 and 442 are susceptible to errors caused by sensor drift (e.g., process, voltage, temperature, or strain changes in absolute temperature sensors 432 / 442), sources of thermal interference, and inaccurate device characterization. This can lead to unreliable or non-repeatable temperature estimates of the surfaces of device 400 or the environment outside device 400 (e.g., temperature estimates from user 460). Ideally, to measure the temperature at rear 450, the absolute temperature sensor would be coupled to or placed adjacent to rear 450. However, such an arrangement may be impractical, or integration challenges may arise due to space considerations for the absolute temperature sensor and / or the challenges of routing power and other signal connections from the printed circuit board to the absolute temperature sensor.

[0072] Figure 4B A schematic diagram of an exemplary configuration comprising multiple thermopile devices coupled according to some examples of this disclosure is shown. Each of the multiple thermopile devices can be used to measure temperature differences to achieve temperature estimation at different locations inside or outside the device. Figure 4B The configuration includes one or more emitter and detector pairs (e.g., corresponding to light emitter 204 and light detector 206) and PCB 440. PCB 440 may represent a printed circuit board including optical sensing circuitry (e.g., corresponding to sensing circuitry 252) and one or more absolute temperature sensors 442. In some examples, Figure 4B The various transmitters / detectors shown in the figure are for E i / D i It can be located in a different position from PCB 440 and absolute temperature sensor 442. Additionally, various transmitters / detectors are available for E... i / D i Each of these can be positioned in a different location, and the temperature can be locally varied, allowing different transmitter / detector pairs to experience different temperatures within the device. In some examples, the transmitter / detector pair E i / D i It can be separated from the absolute temperature sensor 442 via PCB 440. For example, the transmitter / detector for E i / D i It can be mounted on the bottom side of PCB 440, and the absolute temperature sensor 442 can be mounted on the top side of PCB 440. However, for the sake of simplicity in the following discussion, it is assumed that the transmitter / detector is coupled to E. i / D i It can be located at various locations within the device that have a local temperature different from the temperature measured by the absolute temperature sensor 442.

[0073] As described in this article, transmitter E i This may correspond to a light emitter 204 and may optionally include a light-emitting diode (LED). The LED or other light emitter 204 can produce a very narrow visible or invisible light band with an associated centroid wavelength. The centroid wavelength of the LED may change or drift based on the temperature of the LED (e.g., thermal drift). Due to space constraints, the adjacent emitter E... i There may not be enough space to accommodate an absolute temperature sensor 442 for localized temperature measurement. No transmitter E is available. i In accurate temperature measurements, thermal drift can introduce errors into measurements by optical sensors (e.g., measurements of physiological signals or estimations of physiological conditions). In some examples, a thermopile can be used to locally measure the temperature at the emitter, and the locally measured temperature can be used to compensate for its temperature-dependent centroid wavelength drift, and to avoid inaccurate or unreliable downstream estimations of optical sensor data or physiological signals. In some examples, the wavelength of light emitted by the emitter can be estimated based on temperature, and the optical sensing circuitry can tune the emitter's drive so that light is emitted in the correct narrow band. In some examples, the wavelength of light emitted by the emitter can be estimated based on temperature, and the optical sensing system (e.g., signal processor 214) can compensate for wavelength variations to better estimate physiological signals or conditions.

[0074] To improve the accuracy and reliability of the optical equipment on device 400, including the printed circuits 481 and 483 of the corresponding thermopile equipment, the transmitter E of different transmitter / detector pairs can be measured. iThe associated temperature. For example, a first end of the printed circuit 481 may be coupled to PCB 440 and to an absolute temperature sensor 442 on PCB 440. In some examples, the first end of the printed circuit 481 may be bonded to PCB 440 in the vicinity of (e.g., co-located with) the absolute temperature sensor 442. A thermopile device 477 of the printed circuit 481 (represented by a plurality of horizontal lines indicating a thermocouple coupled in series with the thermopile) may span the length of the printed circuit 481 between the absolute temperature sensor 442 and the transmitter E1. The thermopile device 477 may be used to cross signal line 484 (e.g., corresponding to...) Figure 3 The differential signal from the first terminal 315A and the second terminal 315B is used to measure the temperature difference between its first end (e.g., at the absolute temperature sensor 442) and its second end (e.g., at or near the transmitter E1). The transmitter E1 may receive drive and calibration signals from the system (e.g., processor 210, optical sensor controller 212) and / or emit optical signals from the detector D1 via unidirectional or bidirectional lines 482 of the circuit 481. In some examples, the printed circuit 481 may be a flexible printed circuit having a first end bonded to the PCB 440. The flexible printed circuit 481 may then be flexed such that its second end reaches the transmitter E1. In some examples, the transmitter E1 and the detector D1 may be implemented on the flexible printed circuit 481. In some examples, the printed circuit 481 may represent a rigid PCB or may be integrated within the PCB 440 (e.g., when the transmitter E1 is located on the underside of the PCB 440).

[0075] like Figure 4B As shown, in some examples, the second printed circuit 483 can be used to estimate the pair of E from one or more additional transmitters / detectors. i / D i The temperature. For example, Figure 4BA printed circuit 483 is shown, comprising a thermopile for estimating the temperature at transmitter / detector pair E2 / D2 and / or transmitter / detector pair E3 / D3. A first end of the printed circuit 483 may be coupled to an absolute temperature sensor 442 / PCB 440 in a similar manner to that described for printed circuit 481. The printed circuit 483 may be divided into multiple tabs 483-1 and 483-2 at points along its length. A first thermopile device 477A of the printed circuit 483 (represented by multiple horizontal lines indicating thermocouples coupled in series with the thermopile) may span the length of the printed circuit 483 to the end of tab 483-1 (e.g., between absolute temperature sensor 442 and transmitter E2). The first thermopile device 477A may be used to measure the temperature difference between its first end (e.g., at absolute temperature sensor 442) and its second end at tab 483-1 (e.g., at transmitter E2). A differential signal may be measured from line 494-1. The second thermopile device 477B of the printed circuit 483 extends across the length of the printed circuit 483 to the end of the patch 483-1 (e.g., between the absolute temperature sensor 442 and the transmitter E3). The second thermopile device 477B can be used to measure the temperature difference between its first end (e.g., at the absolute temperature sensor 442) and its second end (e.g., at the transmitter E3) at the patch 483-2. The differential signal can be measured from line 494-2.

[0076] Transmitters E2 and E3 may receive drive and / or calibration signals from the system (e.g., processor 210, optical sensor controller 212) and / or transmit optical signals from detectors D2 and D3 (e.g., to optical sensor controller 212) via unidirectional or bidirectional lines 492 of circuit 483. In some examples, printed circuit 483 may be a flexible printed circuit having a first end at PCB 440 and flexing such that one of its tab ends reaches transmitter E2 and the other of its tab ends reaches transmitter E3. In some examples, transmitters E2 / E3 and detectors D2 / D3 may be implemented on tabs 483-1 and 483-2 of the flexible circuit.

[0077] It should be understood that multiple thermopiles can be implemented using one or more printed circuits. In some examples, each printed circuit may include one thermopile (e.g., similar to printed circuit 481 with thermopile 477). In some examples, multiple thermopiles may be implemented on a single printed circuit (e.g., similar to printed circuit 483 with tabs 483-1 and 483-2, including thermopiles 477A-477B). It should be understood that, although... Figure 4B Reference PCB 440 and absolute temperature sensor 442, but the temperature sensing system can be implemented in other locations within the device 400.

[0078] As described in this article, in some examples, it can be based on one or more detectors D i The detected light, based on one or more emitters E i The estimated wavelength of the emitted light is used to estimate physiological characteristics or signals. For example, host processor 210 or temperature sensor controller 240 can measure or estimate the wavelength of one or more emitters E. i The temperature at the location is estimated by each corresponding transmitter E. i The centroid wavelength of the emitted light. Based on a specific emitter E. i Temperature estimation / measurement at the location; the system can be adjusted to work with a specific transmitter E. i The associated driving parameters are used to compensate for any potential drift in the centroid wavelength of a particular transmitter, and are thus based on the input of one or more detectors D. i The detected light is used to improve the accuracy and reliability of physiological characteristics or signals. Alternatively or additionally, the system can be based on each corresponding transmitter E. i The estimated centroid wavelength of the emitted light is used to compensate for the estimation of physiological characteristics or signals.

[0079] It should be noted that the wavelength estimation techniques disclosed herein can be applied to any LED / PD (e.g., light-emitting diode / photodetector components, such as any of the optical sensors 211 and / or any of their components (e.g., light emitter 204), sensing circuitry 208, or photodetector 206) located at any location in the device (e.g., at the crown of the wearable device, at the front crystal module (FCM) (e.g., the front crystal), or at the rear crystal module (BCM) or rear crystal).

[0080] As described in this article, heat flux can be modeled to allow the temperature inside the device to be estimated from the temperature outside the device. Figure 5A Examples of electronic devices according to this disclosure are shown (such as...) Figure 4A A simplified schematic diagram of the heat flux model of the device relative to the user's body. As described above in conjunction with device 400, two absolute temperature sensors 432 and 442 may be located at different locations inside the device (e.g., on separate PCBs 430 and 440, respectively). Model 500 shows two separate nodes, T2 and T1, corresponding to the absolute temperatures at the absolute temperature sensors 432 and 442 within device 400, respectively. Additionally, model 500 shows the resistance R between nodes T2 and T1. 1-2 R 1-2 This can represent the thermal resistance between nodes T2 and T1, or the thermal resistance between absolute temperature sensors 432 and 442. It is worth noting that Model 500 assumes no additional heat sources or sources of thermal interference are located between sensors 432 and 442. At node T2 and T... AMBIENT Additional resistance R between nodesAMB This can represent the thermal resistance between sensor 432 and a region outside device 400 (e.g., the ambient air temperature outside / above device 400). Figure 5A In the simplified model, R AMB This can represent the combined thermal resistance of any component (including portions of PCB 420 and housing 410) between the absolute temperature sensor 432 and the front of device 400 and the external ambient air. At node T1 and T... WRIST Another resistance R between nodes WRIST This can represent the thermal resistance between sensor 442 and user 460 (specifically, for wrist-worn wearable devices, particularly the user's wrist). Figure 5A In the simplified model, R WRIST This can represent the combined thermal resistance of any component (including PCB 440 and rear 450) between sensor 442 and user 460.

[0081] Using Fourier's law, heat flux can be expressed as follows:

[0082]

[0083] Where Q represents the heat flux between two nodes, ΔT represents the temperature gradient or difference between the two nodes, and R represents the thermal resistance between the nodes (1 / R represents the packing thermal conductivity). Using two absolute temperature sensors 432 and 442 that generate temperature measurements T2 and T1 respectively, the temperature at the user's wrist 460 can be expressed using the following expression (sometimes represented by T). WRIST or T w express):

[0084]

[0085] The above expressions provide a model through which temperature measurements T2 and T1 generated by absolute temperature sensors 432 and 442, and R, can be characterized or otherwise determined during the design and / or factory calibration of device 400 (e.g., during manufacturing). WRIST and R 1-2 The value of the wrist temperature T in model 500 is used to estimate the user's wrist temperature. Due to model simplification, the above expression assumes a constant heat flux through each of the PCBs 430 and 440 on which absolute temperature sensors 432 and 442 are located, and further assumes no additional heat source between the absolute temperature sensors 432 and 442. However, these assumptions may not always be valid during operation of device 400, which could lead to inaccurate or unreliable wrist temperature measurements for user 460 using the above expression derived from model 500. Additionally, the wrist temperature T in model 500... wThis typically corresponds to surface skin temperature, which may deviate from core body temperature during vasoconstriction. While the above expression focuses on estimating the user's body temperature, it should be understood that the expression can be modified to alternatively estimate ambient temperature.

[0086] Figure 5B A linear model circuit equivalent is shown for a component within device 400 (or device 1800, detailed below) that can be used to estimate the core body temperature of the wrist of user 460 (or user 1860) using measurements from absolute sensors within device 400 or device 1800. In some examples, the core body temperature can be estimated by summing the core temperature of the wrist and the heat flux through the user's arm multiplied by the thermal resistance through the arm. During vasodilation (e.g., during sleep), the thermal resistance through the arm can approach zero, making the core wrist temperature a close approximation of the core body temperature. As mentioned above, the two absolute temperature sensors 432 and 442 can be located at different locations within device 400 (e.g., on separate PCBs 430 and 440, respectively). Model 550 shows two separate nodes, T2 and T1, corresponding to the temperatures at the absolute temperature sensors 432 and 442 within device 400, respectively. Additionally, model 550 shows the resistance R between nodes T2 and T1. 1-2 R 1-2 This can represent the thermal resistance between nodes T2 and T1, or the thermal resistance between absolute temperature sensors 432 and 442. It is worth noting that, similar to model 500, model 550 assumes no additional heat sources or thermal interference sources between sensors 432 and 442, and also assumes a steady state (e.g., the back of the device and the user's skin are in a steady state). Model 550 includes nodes T2 and T... FC The resistance R between nodes 2-FC This can represent the thermal resistance between the absolute temperature sensor 432 and the front crystal of the device 400 (e.g., corresponding to the region within the device 400 between the PCB 420 and the front crystal) (e.g., the temperature at a location or region adjacent to the PCB 420). R 2-FC This can refer to any component (including portions of PCB 420 and housing 410) located between sensor 432 and the front or front crystal of device 400. Figure 4A The combined thermal resistance (excluding additional components shown in the diagram). T FC Nodes and T A The resistance R between nodes FC-A This can represent the thermal resistance between the front crystal of device 400 and the ambient air outside the front of device 400. R FC-A It can represent the combined thermal resistance of the interface between the front of device 400 or the front crystal and the ambient air above device 400.

[0087] Model 550 also includes T1 nodes and T BC The resistance R between nodes 1-BC This can represent the thermal resistance between the absolute temperature sensor 442 and the subsequent 450. R 1-BC This can represent any component (including PCB 440) between the absolute temperature sensor 442 and the subsequent 450. Figure 4A The combined thermal resistance (of additional components not shown in the diagram). In T BC Nodes and T s The resistance R between nodes (corresponding to the user's skin temperature of 460) CONT This can represent the thermal resistance of 450. And R connected in series. CONT R 1-BC R 1-2 R 2-FC and R FC-A Parallel R S-A This can represent the thermal resistance between the user's skin and the air above the device 400. Finally, in T S Nodes and T C R between nodes (corresponding to the corrected skin temperature that minimizes the effect of heat exchange between the skin (e.g., wrist) and ambient temperature) PHYS This can represent the physiological thermal resistance associated with user 460.

[0088] Φ shown in model 550 BC This corresponds to a heat flux correction factor for the effect of ambient air temperature on skin temperature. The temperature heat flux correction Φ can be expressed using the following expression. BC R0:

[0089] φ BC *R0=h0*(T1-T2)+h1

[0090] Where h0 may represent the multiplier parameter from the characterization of device 400, and h1 may represent the self-heating parameter from the characterization of device 400 and / or the characterization calibration offset from device 400. The estimated temperature of the post-crystal can be expressed using the following expression:

[0091] T BC =T1+a0*(T1-T2)+a1

[0092] Where a0 may represent a multiplier parameter from the characterization of device 400, and a1 may represent a self-heating parameter from the characterization of device 400 and / or a calibration offset from the characterization of device 400. It should be noted that a1 and h1 may be functions or constants. For example, different values ​​of a1 and h1 may be used for different power modes of device 400, such as the power modes discussed later in this disclosure. Specific values ​​of a0 and h0 may be based on the R... 1-BC R1-2 The resistance value and the physiological constant R0 are used to determine this. In some examples, R0 can be determined through laboratory validation (e.g., empirical measurements based on representative samples from users). In some examples, the multiplier parameters a0 and h0 can be expressed using the following expressions:

[0093]

[0094] Specific values ​​of a1 and h1 can represent the impact of the self-heating of device 400 on temperature measurements within the device. In other words, a1 and h1 can represent, or model, the contribution of thermal interference sources (and other heat sources) to temperature measurements within device 400, which in turn can affect the estimation of temperature outside device 400. In some examples, it is desirable to minimize a0 to approach zero. In some examples, a0 is achieved by increasing (and / or maximizing) R. 1-2 To minimize this, methods such as increasing the distance between T1 and T2 and / or inserting a thermally resistive material (such as foam or another thermally resistive substrate) between T1 and T2 can be used. In some examples, a0 is minimized by reducing (and / or minimizing) R. 1-BC To minimize, such as by reducing T1 and R BC The distance between them.

[0095] Based on empirically determined values ​​(e.g., through measurement, laboratory verification, characterization in the factory, etc.) for the various resistances and parameters mentioned above, device 400 can estimate the user's corrected skin temperature or T using the following expression. C :

[0096] T C ≈T BC +φ BC R0, where R0=αR phys +R contact

[0097] Where R phys (For example, R) PHYS ) can represent the physiological thermal resistance associated with the user, α can represent the ratio of heat flow in the user's tissue to heat flow in the device, which may optionally be related to the ratio of heat flow lost around the device (e.g., from the skin to ambient air), and R contact (For example, R) CONT () can represent contact resistance.

[0098] In some examples, such as Figure 4A For example, device 400 is based on two separate absolute temperature sensors (such as...) Figure 4A Temperature measurements T1 and T2 generated by sensors 432 and 442 in the sensor array are used to estimate T. BCHowever, as described herein, each of these absolute temperature sensors may have associated errors or drift caused by variations in the sensor manufacturing process, variations in the supply voltage provided to the sensor, or variations in the sensor's operating temperature. In some examples, as described herein, T can be measured using a thermopile 310. BC To reduce errors or drift, one end is coupled to or otherwise configured to measure the temperature at the rear crystal of device 400 (e.g., attached to rear 450). Specifically, the hot contact 318 of thermopile 310 may be directly defined to rear 450 by an adhesive (e.g., a patterned adhesive layer or conductive epoxy), and the cold contact 312 may be coupled to absolute temperature sensor 254 (e.g., absolute sensor 432 or 442). In such examples, absolute temperature sensor 254 may generate a temperature measurement at its own location within device 400, and thermopile 310 may generate a temperature difference or gradient measurement between its hot contact 318 (e.g., fixed to rear 450) and its cold contact 312 (e.g., co-located with absolute temperature sensor 254). Figure 2 The temperature sensor controller 240 (or host processor 210) can calculate the temperature at the back 450 by summing the absolute temperature measurement from the absolute temperature sensor 254 and the temperature gradient measurement from the thermopile 310 (e.g., the temperature difference between the hot junction and the cold junction of the thermopile).

[0099] Device 400 can utilize model 500 or 550 to estimate wrist temperature (or alternatively, ambient temperature). However, model 550 may rely on fewer assumptions about the absence of self-heating elements (such as sources of thermal interference) within device 400. Additionally or alternatively, model 500 or 550 may also be used in devices comprising multiple absolute temperature sensors or a combination of a single absolute temperature sensor and thermopile 310 (as described herein). Typically, model 550 can also be utilized and / or modified for other arrangements, such as where thermopile 310 is coupled to other surfaces of housing 410 (e.g., the front of device 400 above PCB 420 or PCB 420) to directly measure T. FC When estimating the user's wrist temperature or the user's core body temperature, device 400 can maintain certain user-specific parameters that vary from user to user. In some examples, different users may have different physiological resistance values, such as R. CONT and R PHYS Furthermore, device 400 can be calibrated by the user or depends on the value of the physiological resistance corresponding to a specific user during manufacturing. It should be noted that models 500 and 550 may correspond to those discussed below. Figure 14The core body temperature mentioned in box 1416 is estimated; moreover, another model (e.g., a similar model modified by different resistance values ​​(e.g., thermal resistance values) (and / or more or fewer different resistors)) based on the location of temperature sensors, thermopile, noise interference sources (e.g., internal thermal noise interference source components of the device) can be used and solved to estimate other temperatures, such as one or more of the temperatures described in reference model 550 above. Although described primarily in the context of thermopile (flexible printed circuit or rigid PCB), the techniques described herein are modifiable and / or applicable to electronic devices that include multiple absolute temperature sensors without a thermopile (e.g., as reference model 550). Figure 19 (As described by the model).

[0100] Figure 6A A cross-sectional side view of an exemplary electronic device having temperature sensing circuitry and / or heat flux sensing circuitry integrated with a printed circuit board, according to some examples of this disclosure, is shown. Device 600 may correspond to, except for the barrier 610 between PCB 440 and rear 450. Figure 4A Device 400. Barrier 610 may be a rigid multilayer PCB, which may include an integrated thermopile (e.g., similar to...). Figure 3 The thermopile 310). Specifically, through-holes (such as perforated through-holes, blind through-holes, or embedded through-holes) can be used to form the integrated or embedded thermopile within the barrier 610, as referenced. Figures 7A to 10 As described. PCB 440 may have a bottom surface facing barrier 610 and rear 450, as Figure 6B As shown. Barrier 610 may have a top surface adjacent to, adjacent to, or attached to the bottom surface of PCB 440, sometimes using a patterned adhesive layer. Barrier 610 may also have a bottom surface adjacent to, adjacent to, or attached to rear surface 450, sometimes using a patterned adhesive layer. Interposed between PCB 440 and rear surface 450 in this manner, barrier 610 may include an embedded thermopile having a first contact (e.g., a hot contact) formed at the bottom surface of barrier 610 and a second contact (e.g., a cold contact) formed between the bottom and top surfaces of barrier 610.

[0101] In some examples, through-holes can be used to form an embedded thermopile within the barrier 610. In such examples, the embedded thermopile may have a thermal contact at the bottom surface of the barrier 610 that contacts the rear 450, and a cold contact at the top surface of the barrier 610 that contacts or is otherwise coupled to the PCB 440. An absolute temperature sensor 442 located on the PCB 440 can measure the temperature at the top surface of the PCB 440. The temperature at the rear 450 (T...) BCThe temperature difference or gradient measurement generated by the embedded thermopile of barrier 610 can be added to the absolute temperature measurement generated by sensor 442. In other examples, an embedded thermopile can be formed within barrier 610 using a blind via. In such examples, the embedded thermopile may have a thermal contact at the bottom surface of barrier 610 that contacts the rear 450, and a cold contact below the top surface of barrier 610 that does not extend to PCB 440. The thermopile formed using a blind via may not span the entire thickness of barrier 610, but still provides a temperature sensor controller 240 that can be used to estimate the temperature (T) at the rear 450. BC The temperature difference or gradient measurement is used. In some other examples, embedded thermopile is formed within barrier 610 using buried vias. In such examples, the embedded thermopile has a thermal contact that does not contact the bottom surface of barrier 610 above the rear 450, and a cold contact that does not extend below the top surface of barrier 610 of PCB 440. The thermopile formed using buried vias may not span the entire thickness of barrier 610, but still provides a temperature sensor controller 240 that can be used to estimate the temperature (T0) at the rear 450. BC The temperature difference or gradient measurement value.

[0102] In some examples, the thermopile may be integrated with both PCB 440 and barrier 610. In some examples, the embedded thermopile may have a cold contact at the top surface of PCB 440 and a hot contact at the bottom surface of barrier 610, wherein through-hole vias are used to implement the thermopile through PCB 440 and barrier 610. In some examples, the thermopile may be integrated through some, all, or different combinations of the layers described herein with respect to PCB 440 and / or barrier 610.

[0103] Typically, barrier 610 may have relatively high thermal resistance due to being a thick, rigid PCB. In some examples, for a 100 square millimeter PCB with a thickness of 0.3-1 mm, the thermal resistance may be between 1-5 Kelton / watt. It should be understood that the thermal resistance may be greater or less than the above range, depending on the area, thickness, and material of the PCB. In some examples, the thickness of barrier 610 may be greater than 300 micrometers. In some examples, the thickness of barrier 610 may be greater than 1 mm. In some examples, the thickness of the barrier may be less than 300 micrometers (e.g., 100-300 micrometers). Due to the high thermal resistance of barrier 610 and the reliable sensitivity of its embedded thermopile, barrier 610 may not require the same individual calibration and characterization required for an absolute temperature sensor (such as absolute temperature sensor 442). Any number of thermopiles can be embedded within barrier 610. In some examples, a single thermopile can be used to measure the temperature gradient of a region. In some examples, multiple thermopiles can be used to independently measure the temperature gradient at different locations. In this way, one or more temperature gradients or differential measurements corresponding to the region of barrier 610 or different sub-regions of barrier 610 can be generated, and these measurements are used by temperature sensor controller 240 to measure the temperature of various circuit components, such as circuit components mounted on the bottom surface of PCB 440 adjacent to barrier 610.

[0104] Figure 6B An exploded view of a portion of an exemplary electronic device comprising one or more printed circuit boards and an integrated thermopile, according to some examples of this disclosure, is shown. Figure 6B This can illustrate the relationship between various sensing components and the back of electronic devices. Specifically, Figure 6B The bottom surfaces of PCB 440 and barrier 610 are shown (oriented in...). Figure 6B relative to Figure 6A (The orientations of PCB440 and barrier 610 are reversed). As shown in the figure, multiple transmitter-detector pairs (labeled E) i / D i These emitter-detector pairs can be mounted on the bottom surface of PCB440. They correspond to light emitter 204 and light detector 206 and can be used to measure physiological signals, as described above. Figure 2 As described. Although the description is accurate, it should be understood that multiple optical paths can be formed between a respective transmitter and multiple detectors, or between multiple transmitters and respective detectors. Furthermore, it should be understood that... Figure 6BThe number and / or arrangement of the emitters and detectors are examples and can vary. In some examples, the wavelength of the light emitted by the light emitter 204 may vary with temperature, which can affect the estimation of the physiological characteristics of the light detected by the photodetector 206. Therefore, in some examples, estimating the temperature at the light emitter 204 or the temperature of the region included in the light emitter can provide an estimate of the wavelength of the light emitter. This wavelength estimate can be used to calibrate the emitted wavelength or compensate for the results of photometry or physiological characteristic estimation, which can improve the accuracy of physiological signals derived from such measurements.

[0105] Barrier 610 is shown with cutouts 627 corresponding to the positions of the emitter and detector mounted on the bottom surface of PCB 440. During assembly, cutouts 627 in barrier 610 allow light to be emitted by the emitter and detected by the detector. Additionally, barrier 610 prevents or reduces crosstalk between the light emitter and the photodetector. Through-holes in the thermopile can be represented by unshaded circles adjacent to cutouts 627 in barrier 610. The visible surfaces of these through-holes on the bottom surface of barrier 610 can correspond to the thermal contacts of the thermopile embedded within barrier 610. As an example, through-holes 622-E and 622-D can correspond to two thermopiles for measuring the temperature at emitter E1 and detector D1, respectively, and can optionally generate independent temperature difference or gradient measurements associated with each component. Alternatively, through-holes 622-E and 622-D can together correspond to a single thermopile for the emitter-detector pair E1 / D1, and can generate a single temperature difference or gradient measurement associated with the two adjacent components. Specifically, the thermopile corresponding to the through holes 622-E and 622-D can generate a temperature difference or gradient measurement between the bottom surface (e.g., a thermal junction) of the barrier 610 and another surface within the barrier 610, which may include the top surface of the barrier 610 (e.g., when using perforated through holes to form the thermopile).

[0106] Figure 6B The remaining vias shown are substantially similar to vias 622-E and 622-D, and can similarly correspond to the corresponding components mounted on PCB 440. For example, via 624-E can correspond to transmitter E2, via 624-D can correspond to detector D2, via 626-E can correspond to transmitter E3, via 626-D can correspond to detector D3, via 628-E can correspond to transmitter E4, and via 624-D can correspond to detector D4. Figure 6B Any combination of the vias shown can be coupled together to increase the number of thermocouples within the thermopile, thereby improving thermopile sensitivity, but may reduce the number of potentially independent measurements. The vias 634 in the region between the cutouts 627 can optionally be formed within the barrier 610 (e.g., in the emitter-detector pair corresponding to PCB 440). i / Di (between the incision lines).

[0107] In some examples, Figure 6B All the vias shown are coupled to each other to form individual thermopiles embedded across different regions of barrier 610 to measure temperature differences across barrier 610. When the vias are coupled to form individual thermopiles, their corresponding hot and cold junctions can be formed at the same corresponding layers within barrier 610 to ensure that any output of the individual thermopile corresponds to a temperature gradient or difference across a common distance / thickness within barrier 610. The cold junctions of the thermopiles embedded within barrier 610 can be close together at the top surface of barrier 610 (not shown) and can have two terminals, similar to... Figure 3 The description states that, when considered in conjunction with absolute temperature measurements at or near the location of the cold junction (e.g., the output of sensor 442 on PCB 440), the temperature difference or gradient measurements generated by the thermopile within barrier 610 can be used to directly measure the temperature at the optical sensor (e.g., to estimate wavelength) and / or directly measure the temperature at 450 (T). BC This can improve the accuracy of wrist or core body temperature estimates associated with the user 460.

[0108] Figure 7A Exemplary double-layer rigid printed circuit boards with integrated thermopiles according to some examples of this disclosure are shown in cross-sectional side views, along with optional circuit components mounted on the top and / or bottom surfaces of the PCB. The barrier PCB 700 (e.g., optionally corresponding to barrier 610, but representing any suitable rigid PCB in the device) may be a two-layer rigid board, wherein a core layer 704 is interposed between a top solder mask layer 702 and a bottom solder mask layer 706. As described above... Figure 3 As described in thermopile 310, the thermopile may include a set of thermocouples connected in series. Each thermocouple may correspond to a junction between a first material having a first correlated Seebeck coefficient and a second material having a second correlated Seebeck coefficient different from the first Seebeck coefficient. Figure 7A In this context, a first material having a first Seebeck coefficient may be represented by the letter "A", and a second material having a second Seebeck coefficient may be represented by the letter "B". For illustrative purposes, material A may be or include copper (Cu) (e.g., an epoxy resin or resin having copper particles), and metal B may be or include a copper-nickel (CuNi) alloy, such as constantan (e.g., an epoxy resin or resin having copper and nickel particles or having constantan particles).

[0109] The conductive paths corresponding to two different metals A and B can be respectively... Figure 3Conductive paths 314 and 316. To fabricate the embedded thermopile shown within the barrier PCB 700, vias can be formed through core layer 704 and filled with vias 710 and 712 (e.g., using material A and material B, respectively). Various PCB processing methods using various materials (e.g., high-volume manufacturing processes) can be used to generate vias. Deposition methods for forming different layers include printing materials, dispensing them into holes / vias, and vacuum printing.

[0110] For illustrative purposes, via 710 may be filled with copper, copper particles suspended in epoxy resin, or copper-coated particles suspended in epoxy resin (e.g., according to a "through-hole filling" manufacturing process). Similarly, via 712 may be filled with constantan, constantan particles suspended in epoxy resin, or constantan-coated particles suspended in epoxy resin. Patterning can then be used at the copper layer of the barrier PCB 700 to connect the two vias, such as a copper connector 714 formed above the core layer 704 within the solder mask layer 702. When the metal filling via 710 has a different Seebeck coefficient than the metal filling via 712, connecting vias 710 and 712 with connector 714 forms a thermocouple. Since vias 710 and 712 span the thickness of the core layer 704, the thermopile formed by the tandem combination of such vias measures the heat flux or temperature difference / gradient across the thickness of the core layer 704. As shown on the right side of via 712, another pair of vias similar to vias 710 / 712 is formed, and they are connected in series to via 712 (e.g., using a copper connector below core layer 704). In this way, each pair of connecting vias having a non-conductor-like (e.g., metal) material forms a thermocouple, and connecting such pairs of connecting vias forms a thermopile embedded within the barrier PCB 700.

[0111] The hot contacts of the thermopile embedded within the barrier PCB 700 may be located on a conductive layer on one side of the core 704 (e.g., co-located with solder mask 702), and the cold contacts of the thermopile embedded within the barrier PCB 700 may be located on a conductive layer on the opposite side of the core 704 (e.g., co-located with solder mask 706). In this manner, terminal 716A may show the copper contacts of the cold contacts of the thermopile embedded within the barrier PCB 700, and terminal 716B may show the copper contacts of the hot contacts of the thermopile embedded within the barrier PCB 700. Figure 7A As shown, optional circuit components 720, 722, and 724 can be surface-mounted on the top and bottom surfaces of the barrier PCB 700, and on the thermopile embedded within the core layer 704. In other words, as Figure 7A The integration of the thermopile with the PCB shown still allows other components to be mounted on the PCB.

[0112] Figure 7B It shows having Figure 7AA plan view of an exemplary rigid PCB for an integrated thermopile, specifically corresponding to Figure 7A The cross-section at line A-A'. For example... Figure 7A As shown, line A-A' corresponds to the boundary between core layer 704 and solder mask layer 706. In other examples, Figure 7B The illustration corresponds to a cross-section at the boundary between solder mask 702 and core layer 704. View 750 shows a circular element arranged in an array corresponding to through-holes comprising various materials. For example, through-hole 752-A may comprise copper, while through-hole 752-B may comprise constantan. Figure 7B As shown, vias 752-A and 752-B can be connected to form a thermocouple. Similarly, via 754-A may comprise copper, while via 754-B may comprise constantan, and the two vias can be connected to form another thermocouple. A first thermocouple formed by vias 752-A and 752-B can be connected to a second thermocouple formed by vias 754-A and 754-B, thereby forming a thermopile. The first and second thermocouples can be connected on opposite sides of a care material in a layer not visible in view 750 (e.g., using a copper connector 714). In this way, view 750 may show a single thermopile when all the shown via pairs are interconnected in series on another layer. Alternatively, view 750 may show multiple thermopiles when different independent subsets of the connected via pairs are interconnected in series on another layer.

[0113] although Figure 7A and Figure 7B A two-layer barrier PCB 700 is shown and described, but thermopiles may be embedded or formed within a barrier PCB having more than two layers (e.g., any number of layers). Specifically, two layers may be the minimum number required to form a thermopile, and some PCBs having more than two layers may also be provided with embedded or integrated thermopiles.

[0114] Figure 8 A cross-sectional side view of an exemplary four-layer rigid PCB having an integrated thermopile spanning four PCB layers, according to some examples of this disclosure, is shown. The barrier PCB 800 may be a four-layer PCB having a solder resist layer formed on a top surface 802 and a solder resist layer formed on a bottom surface 810. The four-layer PCB may include a first core layer 804, a second core layer 806, and a third core layer 808. The first core layer 804 may be disposed below the top surface 802 of the solder resist layer, the second core layer 806 may be disposed below the first core layer 804, and the third core layer 808 may be disposed below the second core layer 806. In some examples, the first core layer 804, the second core layer 806, and / or the third core layer 808 may be formed of the same material. A patterned conductive layer may be disposed on the surface of the core layers.

[0115] A first conductive material / metal (e.g., copper) having a first Seebeck coefficient can be represented by the letter "A", and a second conductive material / metal (e.g., constantan) having a second Seebeck coefficient can be represented by the letter "B". The conductive paths corresponding to the two different metals A and B can be respectively... Figure 3 Conductive paths 314 and 316. To fabricate an embedded thermopile shown within the barrier PCB 800, vias can be formed from solder mask 810 through solder mask 802 (e.g., through-holes). Once formed, through-holes 811 and 812, respectively, can be filled with metals A and B (e.g., as referenced). Figure 7A (As described).

[0116] For illustrative purposes, via 811 may comprise copper, copper particles suspended in epoxy resin, or copper-coated particles suspended in epoxy resin (e.g., according to a "through-hole filling" manufacturing process). Similarly, via 812 may comprise constantan, constantan particles suspended in epoxy resin, or constantan-coated particles suspended in epoxy resin. Patterning can then be used at the copper layer of the barrier PCB 800 to connect the two vias, such as a copper connector 814 formed within the solder mask layer 802 above the first core layer 804. When the metal of via 811 has a different Seebeck coefficient than the metal of via 812, using connector 814 to interconnect or couple vias 811 and 812 can form a thermocouple. Because vias 811 and 812 can span the thicknesses of core layers 808, 806, and 804, a thermopile formed by a series combination of such vias can measure the heat flux or temperature difference / gradient across the entire thickness of core layers 808, 806, and 804. As shown on the right side of via 812, another pair of vias similar to vias 811 / 812 can be formed, and they are connected in series to via 812. In this way, each pair of connecting vias having a non-metallic appearance can form a thermocouple, and connecting such pairs of connecting vias can form a thermopile embedded within the barrier PCB 800.

[0117] The hot contacts of the thermopile embedded in the barrier PCB 800 may be located on a conductive layer on one side of the core 804 (e.g., co-located with the solder mask 802), and the cold contacts of the thermopile embedded in the barrier PCB 800 may be located on a conductive layer on the opposite side of the core 808 (e.g., co-located with the solder mask 810). In this manner, terminal 816A may show the copper contacts of the cold contacts of the thermopile embedded in the barrier PCB 800, and terminal 816B may show the copper contacts of the hot contacts of the thermopile embedded in the barrier PCB 800. Although Figure 8 Not shown, but circuit components may be surface-mounted on the top and bottom surfaces of the barrier PCB 800, and embedded in the thermopile within the core layers 808, 806, and 804, as per reference. Figures 7A to 7BA similar approach. Furthermore, in some examples, region 850 (shown to the right of the embedded thermopile) may not be occupied by any thermocouple / thermopile structure, thus leaving space for circuit components (such as component 820) to be embedded within the core layer 806. Relative to Figure 7A Two-layer barrier PCB, Figure 8 The four-layer barrier PCB can provide relatively high thermal resistance and improved sensitivity.

[0118] Figure 9 A cross-sectional side view of an exemplary four-layer rigid PCB having an integrated thermopile spanning two PCB layers (and partially spanning three layers) according to some examples of this disclosure is shown. The barrier PCB 900 may be a four-layer PCB, wherein a solder mask is formed on a top surface 902 and a bottom surface 910. The four-layer PCB may include a first core layer 904, a second core layer 906, and a third core layer 908. The first core layer 904 may be disposed below the top surface 902 of the solder mask, the second core layer 906 may be disposed below the first core layer 904, and the third core layer 908 may be disposed below the second core layer 906. In some examples, the first core layer 904, the second core layer 906, and / or the third core layer 908 may be formed of the same material. A patterned conductive layer may be disposed on the surface of the core layers.

[0119] A first conductive material / metal (e.g., copper) having a first Seebeck coefficient can be represented by the letter "A", and a second conductive material / metal (e.g., constantan) having a second Seebeck coefficient can be represented by the letter "B". The conductive paths corresponding to the two different metals A and B can be respectively... Figure 3 Conductive paths 314 and 316. To fabricate an embedded thermopile shown within the barrier PCB 900, vias can be formed from the solder mask layer 910 through to the second core layer 906 (e.g., blind vias and buried vias). Once formed, through-holes 911 and 912, respectively, can be filled with vias comprising metal A and metal B (e.g., as referenced). Figure 7A (As described).

[0120] For illustrative purposes, via 911 may comprise copper, copper particles suspended in epoxy resin, or copper-coated particles suspended in epoxy resin (e.g., according to a "through-hole filling" manufacturing process). Similarly, via 912 may comprise constantan, constantan particles suspended in epoxy resin, or constantan-coated particles suspended in epoxy resin. Patterning can then be used at the copper layer of the barrier PCB 900 to connect the two vias, such as a copper connector 914 formed above the second core layer 906 within the solder mask layer 902. When the metal of via 911 has a different Seebeck coefficient than the metal of via 912, using connector 914 to interconnect or couple vias 911 and 912 can form a thermocouple. Because vias 911 and 912 can span the thickness of core layers 908 and / or 906 (e.g., primarily for core layer 906 of buried vias), a thermopile formed by a series combination of such vias can measure the heat flux or temperature difference / gradient across the thickness of core layers 908 and 906, but not across the entire barrier PCB 900. As shown on the right side of via 912, another pair of vias similar to vias 911 / 912 can be formed and connected in series to via 912. In this way, each pair of connecting vias having a non-metallic appearance can form a thermocouple, and connecting such pairs of connecting vias can form a thermopile embedded within the barrier PCB 900.

[0121] The hot contacts of the thermopile embedded in the barrier PCB 900 may be located on a conductive layer on one side of core 904 (e.g., co-located with the second core layer 904), and the cold contacts of the thermopile embedded in the barrier PCB 900 may be located on a conductive layer on the opposite side of core 908 (e.g., co-located with the solder mask layer 910). In this manner, terminal 916A may show the copper contacts of the cold contacts of the thermopile embedded in the barrier PCB 900, and terminal 916B may show the copper contacts of the hot contacts of the thermopile embedded in the barrier PCB 900. Although Figure 9 Not shown, but circuit components may be surface-mounted on the top and bottom surfaces of the barrier PCB 900, and on the thermopile embedded in the core layers 906 and 908, as referenced. Figures 7A to 7B Similar to the aforementioned approach. Furthermore, in some examples, region 950 (shown to the right of the embedded thermopile) may not be occupied by any thermocouple / thermopile structure, thus leaving space for circuit components (not shown) to be embedded within the core layer 906, or other through-holes and blind vias (illustrated) may be available for other purposes (e.g., routing signals, etc.). Relative to Figure 7A Two-layer barrier PCB, Figure 9 The four-layer barrier PCB can provide relatively high thermal resistance and improved sensitivity.

[0122] Figure 10A cross-sectional side view of an exemplary four-layer rigid PCB having an integrated thermopile spanning two PCB layers is shown, according to some examples of this disclosure. The barrier PCB 1000 may be a four-layer PCB having a solder resist layer formed on a top surface 1002 and a solder resist layer formed on a bottom surface 1010. The four-layer PCB may include a first core layer 1004, a second core layer 1006, and a third core layer 1008. The first core layer 1004 may be disposed below the top surface 1002 of the solder resist layer, the second core layer 1006 may be disposed below the first core layer 1004, and the third core layer 1008 may be disposed below the second core layer 1006. In some examples, the first core layer 1004, the second core layer 1006, and / or the third core layer 1008 may be formed of the same material. A patterned conductive layer may be disposed on the surface of the core layers.

[0123] A first conductive material / metal (e.g., copper) having a first Seebeck coefficient can be represented by the letter "A", and a second conductive material / metal (e.g., constantan) having a second Seebeck coefficient can be represented by the letter "B". The conductive paths corresponding to the two different metals A and B can be respectively... Figure 3 Conductive paths 314 and 316. To fabricate an embedded thermopile shown within the barrier PCB 1000, vias may be formed from the solder mask layer 1010 through to the third core layer 1008 (e.g., blind vias). Once formed, through-holes may be filled with vias 1011 and 1012, respectively, comprising metal A and metal B (e.g., as referenced). Figure 7A (As described).

[0124] For illustrative purposes, via 1011 may comprise copper, copper particles suspended in epoxy resin, or copper-coated particles suspended in epoxy resin (e.g., according to a "through-hole filling" manufacturing process). Similarly, via 1012 may comprise constantan, constantan particles suspended in epoxy resin, or constantan-coated particles suspended in epoxy resin. Patterning can then be used at the copper layer of the barrier PCB 1000 to connect the two vias, such as a copper connector 1014 formed above the third core layer 1008 within the solder mask layer 1002. When the metal of via 1011 has a different Seebeck coefficient than the metal of via 1012, the use of connector 1014 to interconnect or couple vias 1011 and 1012 can form a thermocouple. Because vias 1011 and 1012 can span the thickness of the core layer 1008, a thermopile formed by a series combination of such vias can measure the heat flux or temperature difference / gradient across the core layer 1008, but not across the entire barrier PCB 1000. As shown on the right side of via 1012, another pair of vias similar to vias 1011 / 1012 can be formed and connected in series to via 1012. In this way, each pair of connecting vias having a non-metallic appearance can form a thermocouple, and connecting such pairs of connecting vias can form a thermopile embedded within the barrier PCB 1000.

[0125] The hot contacts of the thermopile embedded in the barrier PCB 1000 may be located on a conductive layer on one side of core 1008 (e.g., co-located with solder mask 1002), and the cold contacts of the thermopile embedded in the barrier PCB 1000 may be located on a conductive layer on the opposite side of core 1008 (e.g., co-located with second core layer 1006 or more specifically, at the boundary between layers 1006 and 1008). In this manner, terminal 1016A may show the copper contacts of the cold contacts of the thermopile embedded in the barrier PCB 1000, and terminal 1016B may show the copper contacts of the hot contacts of the thermopile embedded in the barrier PCB 1000. Although Figure 10 Not shown, but circuit components may be surface-mounted on the top and bottom surfaces of the barrier PCB 1000, and on the thermopile embedded within the core layer 1008, as per reference. Figures 7A to 7B Similar to the aforementioned approach. Furthermore, in some examples, region 1050 (shown to the right of the embedded thermopile) may not be occupied by any thermocouple / thermopile structure, thus leaving space for circuit components (not shown) to be installed and connected within the core layer 1006, or through-holes and other blind vias (illustrated) may be used for other purposes (e.g., routing signals, etc.).

[0126] Figure 11A cross-sectional side view of an exemplary electronic device having temperature sensing circuitry and / or heat sensing circuitry integrated with flexible circuitry, according to some examples of this disclosure, is shown. Except for the flexible printed circuit (FPC) 1110 extending from the top surface of PCB 440 to the rear 450, device 1100 is substantially similar to... Figure 4A Device 400. FPC 1110 may be a flexible multilayer printed circuit embedded within a portion of its layers, which may include similar... Figure 3 The thermopile 310 is a thermopile. Specifically, the embedded thermopile within FPC 1110 can be formed using conductive paths printed on layers of the FPC, wherein the conductive paths are connected using vias. In some examples, the conductive paths printed on layers of FPC 1110 can extend across its entire (or substantially its entire) length (e.g., the conductive paths can extend from PCB 440 to rear 450). PCB 440 may have a top surface to which the absolute temperature sensor 442 can be surface-mounted. Preferably, the thermopile embedded within FPC 1110 may have a cold contact at a first end that can be coupled to the top surface of PCB 440 and the sensor 442. The thermopile embedded within FPC 1110 may have a thermal contact that can be adjacent to, near, or attached to rear 450, sometimes using a conductive epoxy resin to improve thermal coupling between the thermopile's thermal contact and rear 450. In this configuration, the thermopile embedded within the FPC 1110 measures the temperature difference or gradient between the rear 450 (coupled to its hot junction) and the PCB 440 (coupled to its cold junction). When the absolute temperature sensor 442 and the cold junction of the thermopile embedded within the FPC 1110 are co-located, the sum of the absolute temperature measurement generated at the absolute temperature sensor 442 and the temperature difference measured by the thermopile can estimate the temperature (T) at the rear 450. BC ).

[0127] Typically, embedding a thermopile within the FPC 1110 allows for direct temperature sensing / measurement at impractical surfaces or areas using an absolute temperature sensor 254 within the device 400. (As mentioned above...) Figure 2 As mentioned, absolute temperature sensors may require power supply and additional connections on the PCB, and therefore cannot be fully integrated into certain surfaces, such as the inner surface of the rear 450. Furthermore, the thermopile embedded within the FPC 1110 can measure heat flux across its entire length (or substantially across its entire length), which can result in more accurate and repeatable temperature measurements at a variety of surfaces (compared to using multiple absolute temperature sensors to estimate the temperatures of those surfaces). Depending on the number of conductive paths (sometimes referred to as the "number of turns") of the thermopile within the FPC 1110, the thermopile can have better sensitivity than an absolute temperature sensor.

[0128] Although the FPC 1110 with embedded thermopile is shown extending from sensor 442 to rear 450, the cold and hot contacts of the embedded thermopile can be coupled between any two locations within device 400 (e.g., from PCB 430 to rear 450, from PCB 430 to PCB 440, from PCB 430 to PCB 420, etc.). In some examples, the embedded thermopile within FPC 1110 may have cold contacts coupled to a PCB including an absolute temperature sensor (e.g., one of absolute temperature sensors 432 / 442), and hot contacts coupled to any other location within device 400 (e.g., rear 450, PCB 420, inner surface of the sidewall of housing 410, etc.). In some examples, the hot contacts of the embedded thermopile within FPC 1110 may be coupled to or near circuit components (such as a light emitter 204 that emits light having wavelengths that vary according to temperature). In some examples, the FPC 1110 and its embedded thermopile are coupled between absolute temperature sensors 432 and 442. In some examples, the FPC 1110 and its embedded thermopile may be coupled between absolute temperature sensor 432 and PCB 420. In some examples, the FPC 1110 and its embedded thermopile may be coupled between absolute temperature sensor 442 and PCB 420. In some examples, the FPC 1110 and its embedded thermopile may be coupled between one of the absolute temperature sensors 432 / 442 and the front or front crystal of device 400. In some examples, the FPC 1110 and its embedded thermopile may be coupled between absolute temperature sensor 442 and the inner surface of the device (at the same height as PCB 440 within device 400).

[0129] As mentioned above Figure 3 As described in thermopile 310, FPC 1110 may include a thermopile containing multiple conductive paths or traces. The thermopile of FPC 1110 may be formed across at least two layers of FPC 1110, wherein a first layer is used for conductive paths of a first conductive material / first metal having a first Seebeck coefficient (e.g., conductive path 314), and wherein a second layer is used for conductive paths of a second conductive material / second metal having a second Seebeck coefficient different from the first Seebeck coefficient (e.g., conductive path 316). The first metal may be copper (Cu), and the second metal may be a copper-nickel (CuNi) alloy / constantan. In some examples, the conductive paths of the first metal formed in the first layer of FPC 1110 may partially overlap with two conductive paths of the second metal formed in the second layer of FPC 1110. Vias may be used to connect conductive paths of different metals across different layers.

[0130] Copper conductive paths can be coupled to constantan conductive paths at the hot contacts of FPC 1110 (e.g., the portion of FPC 1110 co-located with absolute temperature sensor 442) and at the cold contacts (e.g., the portion of FPC 1110 fixed to rear 450). As an example, a first copper path in the first layer can extend from the cold contact of FPC 1110 to its hot contact and can be coupled to a first constantan path at the hot contact (e.g., via a via or another interlayer connector). The first copper path and the first constantan path can together form a first thermocouple. The first constantan path can then extend from the hot contact of FPC 1110 to its cold contact and can be coupled to a second copper path at the cold contact (e.g., via a via or another connector). The second copper path can then extend from the cold contact of FPC 1110 to its hot contact and can be coupled to a second constantan path at the hot contact (e.g., via a via or another connector). The second copper path and the second constantan path can together form a second thermocouple that can be coupled in series with the first thermocouple. According to the arrangement of this example, the first constantan path can partially overlap with one or more of the first copper path and the second copper path used to form a thermocouple embedded in the FPC 1110.

[0131] Figure 12A A cross-sectional side view of an exemplary flexible circuit having an inner layer for signal propagation and an outer ground layer protecting the inner layer, according to some examples of this disclosure, is shown. The FPC 1200 may include a first outer layer 1210 (e.g., a shielding layer, a ground / fixed potential layer, etc.) and a second outer layer 1230 (e.g., a shielding layer, a ground / fixed potential layer, etc.), the first outer layer comprising copper potting or patterning, and the second outer layer comprising copper potting or patterning. An inner layer 1220 may include copper patterning for signal routing (e.g., a signal path). Connections between layers 1210 and 1230 may be formed using a via 1240 or any other suitable interlayer connector available on the FPC 1200. The FPC 1200 shows signal lines in layer 1220 for transmitting data signals or any other suitable type of signal from one end of the FPC 1200 to the other end (the ends of the FPC 1200 are not shown in the cross-sectional side view). Figure 12A (As shown in the diagram). In some examples, integrating the thermopile into the FPC already present in device 400 reduces design complexity and saves space within the device. However, as... Figure 12A As shown, all layers of the FPC1200 can be copper layers, while the thermopile requires layers corresponding to two different conductive materials / metals with different corresponding Seebeck coefficients.

[0132] Figure 12B Examples of some of the embodiments based on this disclosure are shown. Figure 12AA modified cross-sectional side view of an exemplary flexible circuit integrated thermopile of an FPC 1250. In some examples, Figure 12A One of the outer layers (e.g., outer layer 1210) may be formed of different materials / metals such as constantan or a copper-nickel (CuNi) alloy outer layer 1212. Although copper may have a lower resistance (e.g., per unit area) than constantan, an outer layer 1212 formed of constantan may be used to provide a ground plane or shielding layer for the inner layer 1220.

[0133] The thermopile can be implemented in the thermopile routing region 1290 adjacent to the via 1240, within the FPC 1250 (e.g., existing patterned or infused traces in adjacent layers 1210, 1220, and 1230). The thermopile routing region 1290 may include conductive paths patterned from the constantan outer layer 1212 and the copper inner layer 1220. As an example, a first copper path within the inner layer 1220 may extend from the cold contact of the FPC 1250 to its hot contact and may be coupled at the hot contact (e.g., via a via or another interlayer connector) to a first constantan path within the outer layer 1212. The first copper path and the first constantan path may together form a first thermocouple. The first constantan path within the outer layer 1212 may then extend from the hot contact of the FPC 1250 to its cold contact and may be coupled at the cold contact (e.g., via a via or another connector) to a second copper path within the inner layer 1220. Then, a second copper path within the inner layer 1220 may extend from the cold contact of the FPC 1250 to its hot contact, and may be coupled at the hot contact (e.g., via a via or another connector) to a second constantan path within the outer layer 1212. The second copper path and the second constantan path may together form a second thermocouple that can be coupled in series with the first thermocouple. According to the arrangement in this example, the first constantan path within the outer layer 1212 may partially overlap with one or more of the first copper path and the second copper path within the inner layer 1220 used to form a thermopile embedded within the FPC 1250.

[0134] Figure 12B The arrangement shown illustrates a three-layer FPC 1250 for maintaining the flexibility of the FPC. However, it should be understood that in some examples, a fourth constantan layer may be added to the FPC 1250, and the thermopile may be integrated with the FPC using conductive paths patterned in the constantan layer and conductive paths patterned in layers 1210, 1220 and / or 1230.

[0135] Figure 13AA cross-sectional side view of an exemplary flexible circuit according to some examples of this disclosure is shown, wherein a first segment uses an inner layer for data signal propagation and a second segment uses an outer layer (or multiple outer layers) for power signal propagation. The FPC 1300 may include: first outer layer segments 1310-1 and 1310-2, which include copper potting or patterning (e.g., shielding / grounding layer, power propagation layer, etc.); and second outer layer segments 1330-1 and 1330-2, which include copper potting or patterning (e.g., shielding / grounding layer, power propagation layer, etc.). Inner layer segments 1320-1 and 1320-2 may include copper patterning for signal routing (e.g., signal paths). Although outer layer segments 1310-1 and 1310-2 are formed on the same layer, they may be electrically isolated, as represented by the gap between segments 1310-1 and 1310-2, or otherwise electrically separated. Similarly, outer segments 1330-1 and 1330-2 may be formed on the same layer, but may be electrically isolated as indicated by the gap between segments 1330-1 and 1330-2 or otherwise electrically separated. However, it should be understood that the FPC 1300 may have a continuous dielectric layer between the conductive layers shown.

[0136] The connection between layers 1310-1, 1320-1, and / or 1330-1 can be formed using one or more through-holes (e.g., through-hole 1340) or any other suitable interlayer connector available on FPC 1300, in a manner similar to that described for FPC 1200. FPC 1300 shows signal lines for transmitting data signals from one end of FPC 1300 to the other for layers 1320-1 and 1320-2 (the ends of FPC 1300 are not shown in the cross-sectional side view). Figure 13A (As shown in the diagram). The FPC1300 also shows power signal lines in layers 1310-2 and / or 1330-2 from one end of the FPC1300 to the other (the ends of the FPC1300 are not shown in the cross-sectional side view). Figure 13A (As shown in the diagram). In some examples, integrating the thermopile into the FPC already present in device 400 reduces design complexity and saves space within the device. However, as... Figure 13A As shown, all layers of the FPC1300 can be copper layers, while the thermopile requires layers corresponding to two different conductive materials / metals with different corresponding Seebeck coefficients.

[0137] Figure 13B Examples of some of the embodiments based on this disclosure are shown. Figure 13AA modified cross-sectional side view of an exemplary flexible circuit integrated thermopile in an FPC 1350. In some examples, because one or more of the outer layers 1310-2 and 1330-2 are routable electrical signals, these layers cannot be replaced with constantan or copper-nickel (CuNi) alloy outer layers without causing a significant increase in power dissipation due to the higher resistance of constantan (relative to copper). Therefore, in some examples, the thermopile can be integrated into the FPC by alternatively replacing the copper inner layers 1320-1 and 1320-2 with the constantan inner layer 1322.

[0138] The thermopile can be implemented in the thermopile routing region 1390 adjacent to the via 1341, within the FPC 1350 (e.g., existing patterned or infused traces in layers 1310-2, 1320-2, and 1330-2 of the second connector adjacent to the FPC 1300). The thermopile routing region 1390 may include conductive paths patterned from the constantan inner layer 1322 and the copper outer layers 1310-1 / 1310-2. As an example, a first copper path within the copper outer layer may extend from the cold contact of the FPC 1350 to its hot contact and may be coupled at the hot contact (e.g., via a via or another interlayer connector) to a first constantan path within the inner layer 1322. The first copper path and the first constantan path may together form a first thermocouple. Then, a first constantan path within the inner layer 1322 may extend from the hot contact of the FPC 1350 to its cold contact, and may be coupled at the cold contact (e.g., via a via or another connector) to a second copper path within the outer layer. The second copper path within the outer layer may then extend from the cold contact of the FPC 1350 to its hot contact, and may be coupled at the hot contact (e.g., via a via or another connector) to a second constantan path within the inner layer 1322. The second copper path and the second constantan path may together form a second thermocouple that can be coupled in series with the first thermocouple. According to the arrangement of this example, the first constantan path within the inner layer 1322 may partially overlap with one or more of the first copper path and the second copper path within the outer copper layer used to form a thermocouple embedded within the FPC 1350.

[0139] Figure 14Exemplary processes for estimating temperatures inside and outside a device (e.g., using absolute temperature sensors and heat flux sensors) according to some examples of this disclosure are illustrated. At 1402, a system (e.g., computing system 200) may use an absolute temperature sensor (e.g., absolute temperature sensors 254, 432, 442) located within the device housing of the system to measure the absolute temperature. As an example, absolute temperature sensor 442 may measure the absolute temperature at a first location within device 400. The absolute temperature sensor may be implemented using a negative temperature coefficient (NTC) temperature sensor, a resistance temperature detector (RTD), or a diode-based temperature sensor. The temperature measurement from the absolute temperature sensor may correspond to the temperature at the first location (e.g., corresponding to the location of the absolute temperature sensor and / or a local area around the sensor).

[0140] At 1404, the system can measure the temperature gradient. In some examples, the temperature gradient may lie between a first location within the device (e.g., corresponding to an absolute temperature sensor) and a second different location. In some examples, the system uses a thermopile or other heat flux sensor 256 to measure the temperature gradient (temperature difference), as described herein.

[0141] At 1406, the system can be based on the absolute temperature measured by the absolute temperature sensor and the temperature measured by the heat flux sensor 256 (e.g., as shown in the image). Figure 3 The thermopile 310 shown measures the temperature gradient / difference to estimate the absolute temperature at a second, different location. In some examples, the second location may be within the device but separated from the first location by the thermopile. In some examples, the system may calculate the sum of the absolute temperature measurement at the first location and the temperature gradient measurement to estimate the absolute temperature at the second location (e.g., at the end of the thermopile or other heat flux sensor). In some examples, such as Figure 6AFor example, the thermopile may be embedded within a rigid PCB of barrier 610 (and / or PCB 440). A first end of the thermopile / barrier may be coupled to the underside of PCB 440, and a second end of the thermopile / barrier may be coupled to rear 450. In some such examples, the system (e.g., host processor 210 or temperature sensor controller 240) may estimate the absolute temperature at rear 450 by adding the temperature gradient / difference measured by the thermopile embedded within the rigid PCB of barrier 610 to the absolute temperature measurement generated at absolute temperature sensor 442. In some examples, the thermopile may be implemented using flexible printed circuit 1110 having a first end coupled to absolute temperature sensor 442 / PCB 440 and a second end coupled to rear 450. In some such examples, the system (e.g., host processor 210 or temperature sensor controller 240) may estimate the absolute temperature at rear 450 by adding the temperature gradient / difference measured by the thermopile embedded within FPC 610 to the absolute temperature measurement generated at absolute temperature sensor 442.

[0142] In some examples, such as Figure 4B For example, multiple thermopile can be used with one or more absolute temperature sensors to estimate the temperature at multiple locations within the device in a similar manner.

[0143] At 1408, the system may optionally estimate the component temperature associated with the heat flux sensor 256. As an example, when the heat flux sensor 256 is a thermopile with ends at or near a location coupled to the system, the system (e.g., temperature sensor controller 240, host processor 210) may estimate the temperature of a particular component based on an estimated absolute temperature at the end of the thermopile (e.g., the absolute temperature estimated at 1406). In some examples, the device may be characterized as estimating the component temperature based on an estimated temperature at a second location. Based on the component temperature estimated at 1408, the system (e.g., power management circuitry 209) may determine its operating condition, such as whether the temperature of any particular component exceeds a predefined upper temperature boundary associated with damaged or unsafe component operation. In some examples, the system may report the component temperature or a condition identified as being associated with the component temperature to a user. In some examples, components of the system may include one or more processors, wireless communication circuitry, a global positioning system, an optical transmitter, etc.

[0144] Alternatively or additionally, at 1410, the system may compensate for the optical sensor or the estimation of one or more physiological signals based on the absolute temperature estimated at 1406. As an example, the light emitter 204 may optionally include an LED that produces a very narrow visible or invisible light band with an associated centroid wavelength. The centroid wavelength of the LED may change or drift based on the temperature of the LED. When the absolute temperature estimated at 1406 corresponds to a temperature associated with a particular light emitter 204, a compensation model (not shown) can be used to determine the centroid wavelength of the particular light emitter, which may be provided as a parameter to the compensation model. In some examples, compensation may alter the stimulus applied to the emitter so that the emitted light falls within a desired narrow light band. In some examples, the estimated wavelength may be provided to processing circuitry for estimating physiological signals based on sensor data from a photodetector 206 associated with the particular light emitter 204 to compensate for the effect of thermal drift of the emitter on the estimation. It should be noted that the wavelength estimation techniques disclosed herein can be applied to any LED / PD (e.g., light-emitting diode / photodetector or photodiode component located anywhere in the device).

[0145] Alternatively or additionally, at 1412, the system may estimate the ambient air temperature outside the device (e.g., outside the housing 410) and / or estimate the surface temperature of the device, such as the temperature of the front crystal or front surface of the device. In some examples, the absolute temperature estimated at a second location at 1406 corresponds to the temperature at the front surface 162 of the device 160, such as... Figure 1F As shown. In other examples, the estimated absolute temperature at 1406 corresponds to a location... Figure 4A The temperature at the top surface of the PCB 420 at the front of the casing 410. Heat flux models (such as...) Figure 5A and Figure 5B The model shown (500 or 550) can be compared with the temperature estimated at 1406 (corresponding to T2 in model 500 and T in model 550). FC Used in conjunction to estimate the ambient air temperature outside the equipment (T) A or T AMBIENT This is sometimes referred to as ambient temperature. In some examples, the estimated ambient air temperature outside the device may be reported to the user (e.g., displayed on a monitor).

[0146] Alternatively or additionally, at 1414, the system may estimate skin temperature, such as the skin temperature of the user's wrist, forehead, temples, or any other body surface that contacts the housing of the system. In some examples, the absolute temperature estimated at 1406 corresponds to a location within the housing that contacts the user's body at its outer surface. As an example, the absolute temperature estimated at 1406 may correspond to a rear 450, which may have an outer surface that contacts the user's wrist at 460 (e.g.,...). Figure 4A (As shown). As another example, the absolute temperature estimated at 1406 may correspond to the front of device 400 (e.g., adjacent to PCB 420), which may have an outer surface that can be pressed against the forehead of user 460 or another person (e.g., by moving a mobile device so that its front is pressed against the forehead). In some examples, temperature sensor controller 240 uses the temperature estimated at 1406 as a heat flux model (such as... Figure 5A and Figure 5B The model shown (500 or 500) is used as input to estimate the skin temperature associated with user 460 (corresponding to the corrected skin temperature T). WRIST T S 、 or T C In some examples, the estimated skin temperature associated with user 460 may be tracked and / or reported to the user (e.g., displayed on a monitor).

[0147] Alternatively or additionally, at 1416, the system may estimate the core body temperature associated with the user 460. In some examples, the absolute temperature estimated at 1406 may correspond to a wrist temperature measured at the back of the device and may be used to estimate body temperature when the user is in a state of vasodilation (e.g., at night when the user is asleep). In other examples, the absolute temperature estimated at 1406 may correspond to a forehead or temple temperature and may be used to measure temperatures equal to or close to the core body temperature at different areas of the subject using the front or strip of the device, so that measurements can be taken at the forehead even during vasoconstriction. For example, the user may bring the front of the wearable device into contact with the forehead to estimate the core body temperature, or attach the strip of the wearable device around the head to estimate the core body temperature. In some examples, the estimated core body temperature may be tracked and / or reported to the user (e.g., displayed on a display). Typically, at 1416, the system may estimate the core body temperature associated with the user based on skin temperature (such as those estimated at 1414). Therefore, the estimated skin temperature from 1414 can optionally be used as input to the heat flux model (e.g., from...). Figure 5A and 5B The parameters of the model (500 or 550) are used to perform 1416 to estimate the user's core body temperature.

[0148] Figure 15 Exemplary processes for operating a device for temperature sensing operations according to some examples of this disclosure are shown. For example, process 1500 may determine that the electronic device for temperature sensing operations corresponds to conditions suitable for a qualified temperature sensing measurement. For example, conditions for a valid temperature sensing measurement may include sufficient contact between the outer surface of the device and the user's skin and / or the absence of movement (e.g., a stationary user having relatively static contact between the front of the device and the user's forehead). At 1502, a system (e.g., a host processor 210) may receive a user request to initiate a temperature measurement at the outer surface of the device. In some examples, in response to a user request, the system (e.g., processor 210) may determine whether one or more criteria associated with the contact conditions of the device at its outer surface are met. As an example, when a user requests a temperature measurement at the wrist (based on a temperature measurement at the back), the system may determine whether criteria associated with the contact conditions between the back and the user's wrist have been met. As another example, when a user requests a temperature measurement at the forehead or temple (based on a temperature measurement at the front or strip of the device), the system may determine whether criteria associated with the contact conditions between the front and the user's forehead or between the strip and the user's temple have been met. As yet another example, when a user requests a temperature measurement of the ambient air surrounding the device, the system can determine whether criteria associated with the contact condition between the front and the ambient air have been met (e.g., no contact condition between the front and any object). It should be understood that the criteria may differ depending on the type of temperature measurement. For example, contact may be expected for body temperature measurements, but not for ambient air temperature measurements. In some examples, process 1500 can be executed without user input to request a temperature sensing measurement (e.g., chance measurement). In some examples, when user input is used to request a temperature measurement, a subset of sensors and / or relaxed associated criteria can be used to determine whether the contact condition of the device's outer surface is suitable for temperature measurement.

[0149] At 1504, the system (e.g., touch and display controller 216) monitors a touch sensor (such as touchscreen 220) to determine whether sensor data from touchscreen 220 indicates that the contact condition of the device corresponding to the requested temperature measurement has been met. As an example, when a user requests a forehead temperature measurement at 1502, touchscreen 220 may be monitored for data indicating that the user's forehead or temple is in contact with touchscreen 220. In some examples, the one or more criteria may include criteria met when an object is detected in contact with the touch sensor. In some examples, the one or more criteria include criteria met when the object is larger than a threshold area of ​​the touch sensor. In some examples, the one or more criteria include criteria that the object corresponds to human tissue (e.g., excluding floating objects such as water droplets). As another example, when a user requests an ambient air temperature measurement, touchscreen 220 may be monitored for data indicating that an object is not in contact with touchscreen 220 (e.g., ensuring that the front and touchscreen are in full contact with the ambient air outside the device).

[0150] Additionally or alternatively, at 1506, the system (e.g., host processor 210, temperature sensor controller 240) may monitor motion and / or orientation sensor 230. In some examples, the system may use data from motion and / or orientation sensor 230 to determine that the user is stationary and / or that the contact between the user and the outer surface of the device is stationary (e.g., less than a threshold amount of movement of the user and / or the device relative to the user). In some examples, the user's motion and / or the device's motion relative to the user's skin may introduce noise (motion artifacts) into the temperature measurement. In some examples, the system may use data from motion and / or orientation sensor 230 to determine whether the user has performed a gesture to satisfy the contact condition for the requested temperature measurement. The gesture to satisfy the contact condition may include a mechanical gesture indicating that the device has been moved to the appropriate position for temperature measurement / estimation. As an example, when a user requests a forehead temperature measurement at 1502, motion and / or orientation sensor 230 may be monitored for data indicating gestures for bringing the wearable device from a first height to a second height associated with the user's forehead or temple and / or rotating the wrist to bring the front of the device to the forehead.

[0151] Alternatively or additionally, at 1508, the system (e.g., temperature sensor controller 240, power dissipation monitoring circuitry 213, etc.) may monitor temperature sensor 250 and / or power dissipation sensor. In some examples, monitoring may determine whether sensor data from sensor 250 indicates that the user has positioned the device to contact a surface corresponding to the requested temperature measurement. As an example, sensor data from temperature sensor 250 may be monitored for temperature within a desired temperature range for the requested temperature measurement (e.g., optionally, a first desired temperature range for wrist temperature measurement, a second desired temperature range for forehead temperature measurement, a third desired temperature range for ambient air temperature, etc.). In some examples, the criteria may include standards that are met when the measured temperature is within the desired range. In some examples, monitoring may determine the power usage of the device (or a subset of components) and its associated temperature effect on the system, or directly measure the temperature of the system. In some examples, when power usage or temperature is too high, the system may abandon temperature measurement or take other actions to improve the situation or suppress the reporting of the measurement value. In some examples, the one or more criteria may include criteria that are met when power usage and / or internal equipment temperature is below power usage and / or temperature thresholds.

[0152] At 1510, the system can determine whether the outer surface of the device has met one or more criteria associated with the contact condition for the requested temperature measurement. When the one or more criteria are met, the system can estimate the temperature. When the one or more criteria are not met, the system can abandon the temperature estimate (or the system can attempt to improve the condition, compensate for the temperature estimate, and / or suppress the estimate reported to the user). The system can use a temperature sensor 250 including a thermopile as described herein (and optionally a heat flux model as described herein) to estimate the temperature.

[0153] Figure 16 Another exemplary process for operating a device for temperature sensing operations, according to some examples of this disclosure, is shown. For example, process 1600 may meet certain criteria (e.g., criteria relating to those conditions described in reference process 1500 and / or temperature and / or power consumption conditions at the device, as described herein). At 1602, the system may receive a user request to initiate a temperature measurement at an outer surface of the device (e.g., wrist, forehead, etc.).

[0154] At 1604, the system can determine whether the device condition permits accurate temperature measurement. In some examples, the system can monitor sensors such as touchscreen 220, motion and / or orientation sensor 230, optical sensor 211, temperature sensor 250, power dissipation monitoring circuitry 213, etc. Specifically, sensor data from these sensors can be monitored to determine whether one or more criteria are met for temperature measurement. These one or more criteria may include the contact condition between the device and the target of temperature measurement (e.g., ensuring the user and device are relatively stationary, ensuring good contact between the device and the user's skin, wrist, forehead, temple, or ambient air) and / or the condition of interference sources on the device (e.g., internal device temperature and / or power consumption exceeding a threshold, thermal interference processes underway (e.g., GPS tracking, etc.)).

[0155] When the system determines that conditions do not allow for accurate temperature measurement, it may abandon the temperature measurement or alternatively attempt to improve the equipment condition. When the system determines that the equipment condition allows for accurate temperature measurement, it may estimate the temperature (e.g., relative to process 1400) as described herein. In some examples, the system may track the estimated temperature and / or report the estimated temperature to the user (e.g., display it on a monitor).

[0156] In some examples, at 1606, the system may implement measures to improve device condition. In some examples, the system may provide the user with instructions to meet one or more criteria. For example, the user may be instructed (e.g., via audio, visual, or text prompts) to reduce movement and / or improve contact between the device's outer surface and the user's skin. In some examples, the system (e.g., host processor 210, power management circuitry 209) may suppress or interrupt power delivery to components associated with high heat dissipation or thermal interference (especially those located near temperature sensor 250). As another example, host processor 210 may request the user to limit, terminate, or delay system processes that may be thermally interfering. For example, the system may reduce display intensity, power down high-power processors, or temporarily disable or limit cellular, Wi-Fi, Bluetooth, or GPS communications. When or after the system implements measures to improve device condition, the system may return at 1604 to determine whether conditions for accurate and reliable temperature sensor measurements are met.

[0157] Figure 17Another exemplary process for operating a device for temperature sensing operation according to some examples of this disclosure is shown. For example, when one or more criteria are met (e.g., indicating a mass temperature measurement), process 1700 may cause the device to report, store, and / or display a temperature estimate, while when one or more criteria are not met, process 1700 may cause the device to suppress or discard (e.g., not report, store, and / or display) the temperature estimate. At 1702, the system may receive a user request to initiate a temperature measurement, as similarly described herein at 1502 and 1602 in processes 1500 and 1600. At 1704, the system (host processor 210 and / or temperature sensor controller 240, etc.) may estimate the temperature at or outside the outer surface of the device (e.g., as referenced). Figure 14 or Figure 16 As described above, and for the sake of brevity, will not be repeated here.

[0158] At 1706, the system can determine whether the equipment condition permits accurate temperature measurement (e.g., in the same or similar manner as described in 1510 of reference process 1500 or process 1600 or 1604, and for the sake of brevity, it will not be repeated here).

[0159] When the system determines that equipment conditions during measurement do not allow for accurate temperature measurement (e.g., due to motion / poor contact or due to electrical / temperature conditions on the equipment), the system may discard the temperature estimate and / or abandon reporting the temperature estimated at 1708. Alternatively, the temperature estimate may be compensated for to remove the influence of the thermal interference source by using measurements from the power dissipation monitoring circuitry and / or models used to derive the impact of power consumption of certain components (e.g., thermal interference sources of system 200).

[0160] When the system determines that the equipment condition does indeed allow for accurate temperature measurement, the system may store the estimated temperature and / or report it (1710) to the user (e.g., display it on a monitor).

[0161] As described in this article, in some examples, the system includes two or more absolute temperature sensors to estimate the temperature inside or outside the device. Figure 18 A cross-sectional side view of an exemplary electronic device including one or more printed circuit boards and temperature sensing circuitry, according to some examples of this disclosure, is shown. Wearable device 1800 may correspond to... Figure 4A The wearable device 400 has additional features. Furthermore, the wearable device 1800 can correspond to... Figure 1E Equipment 150 and / or Figure 1F 160 (or more generally, may correspond to) Figures 1A to 1G (Any of the electronic devices shown). Furthermore, one or more similar elements and features of the wearable device 1800 optionally correspond to... Figure 4A Wearable devices 400 Figure 6A Wearable devices 600 and / or Figure 11 The wearable device 1100 may have one or more similar elements and features. Device 1800 may include a housing 1810 (e.g., corresponding to the housing 164 and the strap 1812) for attachment to user 1860 via a strip 1812 or any other suitable fastener. In some examples, device 1800 may be attached to user 1860 (e.g., exposed skin on the user's body). Device 1800 may correspond to a watch, fitness tracker, bracelet, wristband, or any other device (e.g., optionally for measuring physiological signals associated with user 1860). Device 1800 may be attached to user 1860 around the wrist, arm, head, neck, or on any exposed surface of the body suitable for measuring physiological signals associated with the user.

[0162] Multiple printed circuit boards (PCBs) 1820, 1830, and 1840 are shown within housing 1810. For example, PCB 1820 may be located inside device 1800, on the front (sometimes referred to as the "front crystal"). In some examples, PCB 1820 may be used to implement a touch sensor panel, display, and / or touchscreen (e.g., touchscreen 220) disposed below the front. In the example shown, an absolute temperature sensor 1821 (e.g., a discrete absolute temperature sensor) is mounted to PCB 1820. In some examples, absolute temperature sensor 1821 is mounted on a first side (e.g., the bottom side) of PCB 1820. In some examples, absolute temperature sensor 1821 is mounted on a second side (e.g., the top side) of PCB 1820. In some examples, absolute temperature sensor 1821 is mounted on both sides (e.g., the top and bottom sides) of PCB 1820 or embedded within PCB 1820.

[0163] PCB 1830 may be located inside device 1800, between PCBs 1820 and 1840. In some examples, PCB 1830 includes a host processor 210, a program storage device 202, a touch and display controller 216, an optical sensor controller 212, and / or a temperature sensor controller 240. In the example shown, an absolute temperature sensor 1832 (e.g., similar to...) Figure 2 The absolute temperature sensor 254 is mounted to the PCB 1830. Although shown as being mounted to the top side of the PCB 1830, the absolute temperature sensor 1832 is optionally embedded within the PCB 1830 or mounted to the bottom side or the underside of the PCB 1830.

[0164] In the example shown, PCB 1840 is located within device 1800, below PCB 1830 at or near rear 1850 (sometimes referred to as "rear crystal"). In some examples, PCB 1840 may additionally or alternatively include an absolute temperature sensor 1842 (e.g., a discrete absolute temperature sensor). Although shown mounted to the top side of PCB 1840, the absolute temperature sensor 1842 may optionally be embedded within PCB 1840, mounted to the bottom side or underside of PCB 1840. It should be noted that references... Figure 18 The absolute temperature sensor discussed is optionally a discrete absolute temperature sensor and optionally manufactured from the same or different entities.

[0165] In some examples, the absolute temperature sensor 1842 may be separable from the rear crystal 1850 via PCB 1840, and PCB 1840 may be separable from the housing 1810 (e.g., not in direct contact with housing 1810 due to the presence of one or more interlayers or air gaps). In the illustrated example, device 1800 includes conductive segments 1852 (e.g., rods, through-holes, or other types of conductive segments, including copper or other types of thermally conductive materials). Each of the illustrated conductive segments 1852 optionally represents one or more conductive segments, but in various examples, more or fewer conductive segments are included in the electronic device. The conductive segments optionally reduce the thermal resistance (increase thermal conductivity) between PCB 1830 and the rear crystal 1850.

[0166] PCB 1840 may include an optical sensor 211 configured to emit light and detect light passing through rear 1850 (e.g., the light emitter and detector are mounted on opposite sides of PCB 1840). The number of PCBs, the number of temperature sensors, and the placement of the PCBs... Figure 18 The component distribution between the PCBs shown is representative and not limiting. For example, fewer or more PCBs may be used, fewer temperature sensors may be used (e.g., absolute temperature sensor 1832 or absolute temperature sensor 1842 may be omitted), more temperature sensors may be used than those in the exemplary device shown, or the components of system 200 may be distributed differently across the one or more PCBs. For example, in some examples, device 1800 includes absolute temperature sensors 1821 and 1842 but excludes absolute temperature sensor 1832. Although Figure 18 The absolute temperature sensor shown is mounted to the corresponding PCB, but it should be understood that the temperature sensor is not limited to being mounted to a PCB. One or more absolute temperature sensors can be integrated into the device (e.g., bonded to a housing, integrated into another component, or within a PCB). Additionally, more than one absolute temperature sensor can be mounted on the same PCB.

[0167] In some examples, the heat flux through device 1800 can be calculated using one or more of discrete absolute temperature sensors 1821, 1832, and 1842 (with or without a thermopile). As an example, the temperature difference between the absolute temperature sensors mounted on PCBs 1830 and 1840 can be determined by subtracting the temperature measured by sensor 1842 from the temperature measured by sensor 1832. This temperature difference can then be used to calculate the heat flux through the device, as well as to estimate the temperature outside the device (e.g., ambient air temperature at the back crystal or body temperature at the back crystal 450).

[0168] Figure 19 A simplified schematic diagram of the heat flux model of an electronic device relative to a user's body according to some examples of this disclosure is shown. One or more similar elements and features of model 1900 of wearable device 1800 optionally correspond to one or more elements and similar features of model 500 and / or model 550. In the example shown, the thermal resistance R... FC It is located between the glass section and the FC MLB (front crystal main logic board). In the example shown, the absolute temperature sensor for measuring temperature T2 is located on the FC MLB (e.g., in...). Figure 18 (On the PCB 1820). In the example shown, R 1-2 The thermal resistance in the distance between the absolute temperature sensor measuring temperature T2 and the absolute temperature sensor measuring temperature T1, in the example shown, is lower than that of the system-in-package (SiP) circuit (e.g., lower than...). Figure 18 PCB 1830) and mounted to the main logic board (e.g., Figure 18 PCB 1840).

[0169] Furthermore, model 1900 includes features for increasing the thermal conductivity (reducing thermal resistivity R) between the printed circuit board (e.g., PCB 1840) and the back crystal (e.g., back crystal 1850). BC The conductive section of the MLB (e.g., a logic board, such as the main logic board) and BC (back crystal) includes a material with low thermal conductivity (and therefore high thermal resistance) (e.g., a substrate or injection-molded plastic material, such as a liquid crystal polymer). Such materials can reduce undesirable coupling between components of the electronic device, such as between the PCB and the back crystal. However, it is desirable to have a sufficient level of conductivity between the MLB and BC such that R... BC (For example, Figure 5B R 1-BC The decrease in temperature T can also reduce a0 as described above in reference model 550 of this disclosure. BCErrors (e.g., corresponding to the temperature of the crystal after it optionally contacts the user) can increase thermal coupling with the user's skin. To increase thermal conductivity (e.g., reduce R...) BC (For example, Figure 5B R 1-BC The conductive section is located on the printed circuit board (e.g., Figure 18 PCB 1840) and subsequent crystal (e.g., Figure 18 Between the MLB (after crystal 1850) and the SiP circuitry. In some examples, methods for manufacturing electronic devices include embedding and / or spraying conductive segments (e.g., vias, such as copper vias) in a material with low thermal conductivity (and therefore high thermal resistance) between the MLB and the BC. In some examples, methods include adding a thermally conductive pressure-sensitive adhesive (PSA) to adhere to the layer in which the conductive segments are added. In some examples, methods for manufacturing electronic devices include adding conductive segments using a process such as laser direct structuring (LDS). Another benefit of increasing the thermal conductivity between the MLB and the BC (after crystal) and the SiP circuitry is that the settling time of internal thermal disturbance sources can be reduced because heat is coupled to the user's skin through the conductive segments from internal thermal disturbance sources (e.g., electrical components, haptic engines, one or more processors, system circuitry in the chip, or another internal thermal disturbance source of the electronic device). (E.g., the user's skin can be used as a heat sink for heat generated by internal thermal disturbance sources of the electronic device.) For example, the amplitude, rise time, and fall time of thermal interference noise can be reduced by integrating conductive sections into electronic devices.

[0170] Therefore, based on the above, some examples of this disclosure relate to an electronic device (e.g., Figure 18 An exemplary electronic device includes a plurality of absolute temperature sensors, the plurality of absolute temperature sensors including a first absolute temperature sensor for measuring a first temperature at a first location in the electronic device (e.g., ...). Figure 18 The absolute temperature sensor 1842), and a second absolute temperature sensor (e.g., for measuring a second temperature at a second location in an electronic device) for measuring a second temperature at a second location in an electronic device. Figure 18 The absolute temperature sensor 1821). The electronic device optionally also includes one or more processors for estimating the temperature of the user of the electronic device using the following (e.g., Figure 2 The host processor 210 and / or Figure 2 Other controllers or processors): The first temperature measured by the first absolute temperature sensor (e.g., as referenced). Figure 19 The T1 discussed, and the second temperature measured by the second absolute temperature sensor (e.g., as referenced) Figure 19The first thermal resistance (e.g., as referenced in T2) between the first position in the electronic device and the second position in the electronic device. Figure 19 The R discussed 1-2 ), and the second thermal resistance between the electronic device and the user of the electronic device (e.g., as referenced). Figure 19 The R discussed CONT and / or R BC ).

[0171] In some examples, the electronic device further includes a first printed circuit board (e.g., PCB 1820) and a second printed circuit board (e.g., PCB 1840). A first absolute temperature sensor (e.g., absolute temperature sensor 1842) is optionally mounted to the first printed circuit board, and a second absolute temperature sensor (e.g., absolute temperature sensor 1821) is optionally mounted to the second printed circuit board. In some examples, the first absolute temperature sensor (e.g., absolute temperature sensor 1842) mounted to the first printed circuit board and the second absolute temperature sensor (e.g., absolute temperature sensor 1821) mounted to the second printed circuit board are vertically aligned in the electronic device (or within a threshold level tolerance relative to vertical alignment). In other examples, the first and second absolute temperature sensors are not vertically aligned. In some examples, the distance between the first and second absolute temperature sensors in the electronic device is maximized. In other examples, the distance is minimized. In still other examples, the distance is between a maximum distance and a minimum permissible distance within the electronic device (e.g., a distance of 3 mm, 5 mm, 6 mm, or another distance). In some examples, the second printed circuit board (e.g., PCB 1820) includes circuitry for touch or display operations of the electronic device, and the first printed circuit board (e.g., PCB 1820) includes circuitry for physiological sensing operations of the user's physiological attributes of the electronic device.

[0172] In some examples, the electronic device further includes a third printed circuit board (e.g., PCB 1830) between the first and second printed circuit boards. In some examples, a system-in-package (SiP) circuit is mounted to the third printed circuit board and one or more processors are included in the SiP circuit. In some examples, the electronic device includes a third absolute temperature sensor (e.g., absolute temperature sensor 1832) that is mounted to the third circuit board or anchored to the housing of the electronic device (e.g., housing 1810).

[0173] In some examples, the second thermal resistance between the electronic device and the user of the electronic device corresponds to the thermal resistance of the contact interface between the electronic device and the user's skin (e.g., R). CONT(such as those described in reference models 550 and 1900) and the thermal resistance of the user's organization in electronic devices (e.g., R). PHYS (as described and / or shown in reference models 550 and / or 1900).

[0174] In some examples, the multiple absolute temperature sensors of the electronic device also include a third absolute temperature sensor (e.g., absolute temperature sensor 1832) for measuring a third temperature at a third location in the electronic device, and a fourth absolute temperature sensor configured to measure a fourth temperature at a fourth location in the electronic device. In some examples, estimating the user's temperature in the electronic device further utilizes the third temperature measured by the third absolute temperature sensor and the fourth temperature measured by the fourth absolute temperature sensor. Thus, in some examples, the user's calibrated skin temperature or T... C Optionally, the function (as described and / or shown in reference models 550 and / or 1900) is a function of: a first temperature measured by a first absolute temperature sensor, a second temperature measured by a second absolute temperature sensor, a third temperature measured by a third absolute temperature sensor, and a fourth temperature measured by a fourth absolute temperature sensor, and thermal resistance values ​​based on the respective positions of the four absolute temperature sensors relative to the electronic device. Thus, thermal resistance values ​​different from the first and second thermal resistances are optionally used and are based at least on the respective positions of the four absolute temperature sensors relative to the electronic device. In some examples, the electronic device includes more than four absolute temperature sensors.

[0175] In some examples, the electronic device includes one or more conductive segments (e.g., rods, through-holes, or conductive segments of another shape) extending from a first printed circuit board toward the outer surface of the electronic device's housing and configured to increase the thermal conductivity (or reduce the thermal resistance) between the second absolute temperature sensor and the outer surface of the housing, such as a reference... Figure 18 and Figure 19 The described conductive section. In some examples, one or more conductive rods are configured to contact the housing, at least penetrate a portion of the housing, or be exposed on the outer surface of the housing.

[0176] In some examples, the first thermal resistance between the first and second positions (such as R described in reference models 550 and 1900) 1-2 The thermal resistance can be determined using empirical measurements from one or more devices that are similar to, but do not include, electronic devices, such as through factory calibration or testing processes. For example, empirical measurements can be performed using a specific electronic device model and / or for a set of test users. One or more of the empirically derived thermal resistances can be used for temperature sensing of electronic devices of the same model type without requiring factory calibration of the thermal resistance of the electronic device.

[0177] In some examples, the first thermal resistance between the first and second positions (such as R described in reference models 550 and 1900) 1-2 It is determined using empirical measurements from one or more devices, including electronic equipment, such as through factory calibration or testing processes.

[0178] In some examples, the second thermal resistance corresponding to the second thermal resistance between the electronic device and the user of the electronic device (such as R described in reference models 550 and 1900) CONT and / or R PHYS It is determined using empirical measurements taken by users excluding electronic devices.

[0179] In some examples, the first thermal resistance (such as R described in reference models 550 and 1900) 1-2 ) and / or a second thermal resistance (such as R described in reference models 550 and 1900) CONT and / or R PHYS This is determined using one or more Stock Units (SKUs) (e.g., product identifiers) of an electronic device or a part of an electronic device. For example, one or more processors may execute information for accessing one or more SKUs corresponding to the electronic device, and for determining a first thermal resistance (e.g., such as a reference) based on one or more SKUs. Figure 19 The R discussed 1-2 The operation of the device. Information corresponding to one or more SKUs optionally depends on the size of the electronic device, the material of the electronic device's housing, the manufacturer of the electronic device and / or parts thereof, and / or other components of the electronic device and / or parts thereof. For example, a first example of the device optionally includes a first set of SKUs indicating a first set of the device's geometry and material, and a second example of the device optionally includes a second set of SKUs indicating a second set of the device's geometry and / or material (optionally different from the first set of the device's geometry and / or material). The thermal resistance derived for the first example of the device is optionally different from the thermal resistance derived for the second example of the device, based at least in part on the first set of SKUs and the second set of SKUs, respectively. In some examples, one or more thermal resistances may be stored or programmed in registers or other memory circuits based on SKUs, and these one or more thermal resistances may be accessed for temperature sensing as described herein.

[0180] In some examples, the second thermal resistance (such as R described in reference models 550 and 1900) CONT and / or R PHYS The determination is made during calibration (e.g., by the user and / or on-site calibration) and when the user comes into contact with the electronic device (e.g., when it is worn by the user).

[0181] In some examples, the electronic device may include at least two power mode operations, a first power mode and a second power mode, whereby the electronic device operates in the second power mode (e.g., it optionally includes...). Figure 2 The lower power processor 211-1 uses less power in operation than the electronic device in the first power mode (which optionally includes...) Figure 2 The power usage in the operation of the higher power processor 211-2. In some examples, one or more processors estimate the user's temperature when the electronic device operates in a second power mode. In some examples, one or more processors estimate the user's temperature when the electronic device operates in a first power mode. In some examples, one or more processors may estimate the user's temperature when the electronic device operates in a first power mode and also when the electronic device operates in a second power mode. In some examples, the use of temperature sensing in different modes is optionally determined based on the suitability for conditions for qualified temperature sensing measurements such as those described in reference process 1500.

[0182] In some examples, the second position (e.g., Figure 18 The first distance between the absolute temperature sensor 1821 (measuring the second temperature at its location) and the user of the electronic device (e.g., the skin of user 1860) is greater than a threshold distance, such as 2 mm, 3 mm, 5 mm, 6 mm, or another threshold distance. In some examples, the second location (e.g., Figure 18 The absolute temperature sensor 1821 measures a second temperature at a location that is a second distance between the electronic device's rear crystal (e.g., rear 1850) and the surface of the electronic device configured to contact the user's skin. Figure 18 The distance (1862) is greater than a threshold distance, such as 2mm, 3mm, 5mm, or optionally another threshold distance greater than 5mm. In some examples, the first position (e.g., Figure 18 The third distance between the absolute temperature sensor 1842 (which measures the second temperature at a location) and the user of the electronic device (e.g., the skin of the user 1860) is greater than a threshold distance, such as 1 mm, 2 mm, 5 mm, or another threshold distance.

[0183] In some examples, in electronic devices (e.g., Figure 18 The method is performed at an exemplary electronic device, the electronic device including a plurality of absolute temperature sensors, the plurality of absolute temperature sensors including a first absolute temperature sensor (e.g., ...). Figure 18 The absolute temperature sensor 1842) and the second absolute temperature sensor (e.g., Figure 18 The method includes using a first absolute temperature sensor 1821 to measure a first temperature at a first location in the electronic device (e.g., as referenced). Figure 19The T1 discussed; using a second absolute temperature sensor to measure a second temperature at a second location in the electronic device that is different from the first location (e.g., as referenced). Figure 19 The T2 discussed; and the user's temperature for the electronic device is estimated using the following: a first temperature measured by a first absolute temperature sensor (e.g., as referenced). Figure 19 The T1 discussed, and the second temperature measured by the second absolute temperature sensor (e.g., as referenced) Figure 19 The first thermal resistance (e.g., as referenced in T2) between the first position in the electronic device and the second position in the electronic device. Figure 19 The R discussed 1-2 ), and the second thermal resistance between the electronic device and the user of the electronic device (e.g., as referenced). Figure 19 The R discussed CONT and / or R BC In some examples, the method includes one or more additional operations described in this disclosure.

[0184] In some examples, a non-transitory computer-readable storage medium stores one or more programs, said one or more programs including instructions, said instructions being communicated by a device comprising a first absolute temperature sensor (e.g., Figure 18 The absolute temperature sensor 1842) and the second absolute temperature sensor (e.g., Figure 18 Electronic devices with multiple absolute temperature sensors (e.g., absolute temperature sensor 1821) Figure 18 When executed by one or more processors of an exemplary electronic device, the electronic device is caused to perform the methods described above. Additionally, in some examples, the methods include one or more additional operations described in this disclosure.

[0185] Some examples of this disclosure relate to a heat flux sensor comprising: a printed circuit board (PCB) including a thermopile, wherein the thermopile includes a plurality of thermocouples connected in series, and wherein the PCB is rigid; a plurality of vias in the PCB, the plurality of vias including one or more first vias from a first layer to a second layer of the PCB and one or more second vias from the first layer to the second layer of the PCB, the one or more first vias including a first conductive material having a first Seebeck coefficient, the one or more second vias including a second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient; a plurality of conductive traces on the first layer and the second layer of the PCB, the plurality of conductive traces interconnecting the plurality of vias; and a sensing circuit coupled to the thermopile and configured to measure a voltage proportional to a temperature gradient between the first layer and the second layer of the PCB. Additionally or alternatively, in some examples, each of the plurality of thermocouples includes a via of one of the first vias and one of the second vias coupled through one of the conductive traces of the plurality of conductive traces. Alternatively or alternatively, in some examples, the plurality of vias includes through-hole vias from the first layer to the second layer. Alternatively or alternatively, in some examples, the PCB includes a third layer and a fourth layer, the third layer and the fourth layer being located between the first layer and the second layer; and the plurality of vias includes through-hole vias. Alternatively or alternatively, in some examples, the PCB includes a third layer and a fourth layer, the first layer and the second layer being located between the third layer and the fourth layer; and the plurality of vias includes buried vias. Alternatively or alternatively, in some examples, the PCB includes a third layer and a fourth layer, the first layer and the second layer being located above the third layer and the fourth layer, or the first layer and the second layer being located below the third layer and the fourth layer; and the plurality of vias includes blind vias. Alternatively or alternatively, in some examples, the sensing circuit includes: a differential amplifier coupled to the thermopile, wherein a first terminal of the thermopile is coupled to a first input of the differential amplifier, and a second terminal of the thermopile is coupled to a second input of the amplifier, the second input being different from the first input of the amplifier. Alternatively or alternatively, in some examples, the sensing circuit further includes an analog-to-digital converter coupled to the output of the differential amplifier configured to convert the output into a digital signal. Alternatively or alternatively, in some examples, the sensing circuit is mounted on the surface of the PCB. Alternatively or alternatively, in some examples, the first Seebeck coefficient is a positive Seebeck coefficient and the second Seebeck coefficient is a negative Seebeck coefficient.Alternatively or alternatively, in some examples, the first conductive material is copper and the second conductive material is constantan. Alternatively or alternatively, in some examples, the plurality of conductive traces comprise copper. Alternatively or alternatively, in some examples, the PCB has a thickness greater than 300 micrometers. Alternatively or alternatively, in some examples, the PCB has a thickness greater than 1 millimeter.

[0186] Some examples relate to an electronic device comprising: an absolute temperature sensor configured to estimate a first temperature; a heat flux sensor comprising: one or more printed circuit boards (PCBs) including a thermopile comprising a plurality of thermocouples connected in series, and wherein the one or more PCBs are rigid; and a plurality of vias in the one or more PCBs, the plurality of vias including one or more first vias from a first layer to a second layer of the one or more PCBs and one or more second vias from the first layer to the second layer of the one or more PCBs, the one or more first vias comprising a first conductive material having a first Seebeck coefficient. One or more second vias include a second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient; a plurality of conductive traces on the first layer and the second layer of the one or more PCBs, the plurality of conductive traces interconnecting the plurality of vias; and sensing circuitry coupled to the thermopile and configured to measure a signal (such as an electrical characteristic, such as a voltage signal, or another type of signal) proportional to a temperature gradient between the first layer and the second layer of the one or more PCBs; and processing circuitry coupled to the sensing circuitry and the absolute temperature sensor, the processing circuitry being configured to estimate a second temperature using the first temperature and the signal proportional to the temperature gradient. Additionally or alternatively, in some examples, the absolute temperature sensor includes: a negative temperature coefficient (NTC) temperature sensor, a resistance temperature detector (RTD), or a diode-based temperature sensor. Additionally or alternatively, in some examples, the electronic device further includes a housing; wherein the absolute temperature sensor is disposed within the housing and configured to estimate the first temperature at a first location within the housing. Alternatively or alternatively, in some examples, the electronic device is a wearable device, and the second temperature is the skin temperature at the contact point between the user's skin and the wearable device. Alternatively or alternatively, in some examples, the second temperature is the ambient temperature outside the electronic device. Alternatively or alternatively, in some examples, the first temperature corresponds to a first location within the electronic device, and the second temperature corresponds to a second location within the electronic device, the second location being different from the first location. Alternatively or alternatively, in some examples, the second location is separated from the first location by the one or more PCBs. Alternatively or alternatively, in some examples, the electronic device further includes a display, the display comprising the one or more PCBs.Alternatively or alternatively, in some examples, the electronic device further includes an optical sensor comprising: one or more photoemitters; and one or more photodetectors; and wherein the one or more PCBs of the heat flux sensor comprise a first PCB and a second PCB, wherein the one or more photoemitters and the one or more photodetectors of the optical sensor are disposed on the first PCB, and the second PCB includes an optical spacer between the optical sensor and a rear crystal of the electronic device, and wherein the second temperature corresponds to the optical sensor. Alternatively or alternatively, in some examples, the first PCB and the second PCB are coupled together by an adhesive. Alternatively or alternatively, in some examples, the processing circuitry is further configured to estimate the wavelength of at least one of the one or more photoemitters. Alternatively or alternatively, in some examples, the processing circuitry is further configured to estimate physiological characteristics using the wavelength of the optical sensor and at least one of the one or more photoemitters. Alternatively or alternatively, in some examples, the one or more PCBs have a thickness greater than 300 micrometers. Alternatively or alternatively, in some examples, the one or more PCBs have a thickness greater than 1 millimeter.

[0187] Some examples relate to a method comprising: measuring a first temperature at a first location using an absolute temperature sensor; estimating heat flux through a rigid printed circuit board comprising a plurality of vias, the plurality of vias including one or more first vias and one or more second vias, the one or more first vias comprising a first conductive material having a first Seebeck coefficient, the one or more second vias comprising a second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient, wherein the plurality of vias are interconnected to form a thermopile; and estimating a second temperature at a second location different from the first location. Additionally or alternatively, in some examples, estimating the heat flux through the rigid printed circuit board comprises: measuring a differential voltage across the thermopile; and estimating the heat flux using the differential voltage, the thermal resistance of the rigid printed circuit board, and the thermoelectric sensitivity of the thermopile. Additionally or alternatively, in some examples, the second temperature is measured as the skin temperature at a contact point between a user's skin and an electronic device including the rigid printed circuit board. Additionally or alternatively, in some examples, the second temperature is the ambient temperature outside the electronic device including the rigid printed circuit board. Alternatively or in some examples, the first temperature corresponds to a first location within an electronic device including the rigid printed circuit board, and the second temperature corresponds to a second location within the electronic device, the second location being separated from the first location by the rigid printed circuit board.

[0188] Some examples of this disclosure relate to a heat flux sensor comprising a flexible printed circuit board (PCB) including a thermopile comprising a plurality of thermocouples connected in series. The flexible PCB includes: a first conductive layer comprising a first conductive material having a first Seebeck coefficient; a second conductive layer comprising a second conductive material having a second Seebeck coefficient, which is different from the first Seebeck coefficient; a plurality of vias located between the first and second conductive layers; and a sensing circuit coupled to the thermopile and configured to measure a voltage proportional to a temperature gradient between a first end and a second end of the flexible PCB. Additionally or alternatively, in some examples, the first conductive layer is patterned with a first plurality of conductive traces of the first conductive material, and the second conductive layer is patterned with a second plurality of conductive traces of the second conductive material. Additionally or alternatively, in some examples, each of the plurality of thermocouples includes a conductive trace of the first plurality of conductive traces and a conductive trace of the second plurality of conductive traces coupled through one of the vias. Alternatively or alternatively, in some examples, the plurality of vias includes a plurality of first vias and a plurality of second vias, wherein the plurality of first vias are disposed within a first threshold distance of the first end of the flexible PCB, and wherein the plurality of second vias are disposed within a second threshold distance of the second end of the flexible PCB. Alternatively or alternatively, in some examples, the first threshold distance and the second threshold distance are less than 50 micrometers. Alternatively or alternatively, in some examples, a first conductive trace in the first plurality of conductive traces and a second conductive trace in the first plurality of conductive traces each partially overlap with a first conductive trace in the second plurality of conductive traces, such that the first conductive trace in the first plurality of conductive traces is electrically coupled to the first conductive trace in the second plurality of conductive traces through the first vias of the plurality of vias of the flexible PCB, and the second conductive trace in the first plurality of conductive traces is electrically coupled to the first conductive trace in the second plurality of conductive traces through the second vias of the plurality of vias of the flexible PCB. Alternatively or additionally, in some examples, the sensing circuit includes: a differential amplifier coupled to the thermopile, wherein a first terminal of the thermopile is coupled to a first input of the differential amplifier, and a second terminal of the thermopile is coupled to a second input of the amplifier, the second input being different from the first input of the amplifier. Alternatively or additionally, in some examples, the sensing circuit further includes: an analog-to-digital converter coupled to the output of the differential amplifier configured to convert the output into a digital signal.Alternatively or alternatively, in some examples, the sensing circuit further includes: a bias amplifier configured to generate a bias voltage as its output, wherein the output of the bias amplifier is coupled to a first input of the differential amplifier and coupled as a reference voltage to the analog-to-digital converter. Alternatively or alternatively, in some examples, the sensing circuit is mounted on the surface of a rigid PCB, and the first end of the flexible PCB is coupled to the rigid PCB. Alternatively or alternatively, in some examples, the first end of the flexible PCB is bonded to the rigid PCB by a conductive adhesive. Alternatively or alternatively, in some examples, the first Seebeck coefficient is a positive Seebeck coefficient and the second Seebeck coefficient is a negative Seebeck coefficient. Alternatively or alternatively, in some examples, the first conductive material is copper and the second conductive material is constantan. Alternatively or alternatively, in some examples, the flexible PCB includes one or more signal traces or one or more power traces independent of the thermopile, the one or more signal traces or one or more power traces being configured to route one or more signals or one or more power supplies from the first end of the flexible PCB to the second end of the flexible PCB. Alternatively or alternatively, in some examples, the flexible circuit includes a third conductive layer comprising the first conductive material, the first conductive layer being positioned between the second conductive layer and the third conductive layer; the one or more signal traces are implemented using the first conductive material in the first conductive layer and are shielded by the second conductive material in the second conductive layer and the first conductive material in the third conductive layer. Alternatively or alternatively, in some examples, the flexible circuit includes a third conductive layer comprising the first conductive material, the second conductive layer being positioned between the first conductive layer and the third conductive layer; the one or more signal traces are implemented using the second conductive material in the second conductive layer and are shielded by the first conductive material in the first conductive layer and the first conductive material in the third conductive layer.

[0189] Some examples relate to an electronic device comprising: a rigid printed circuit board (PCB); an absolute temperature sensor configured to estimate a first temperature and coupled to the rigid PCB; and a heat flux sensor comprising: a flexible PCB including a thermopile comprising a plurality of thermocouples connected in series, the flexible PCB including: a first conductive layer comprising a first conductive material having a first Seebeck coefficient; a second conductive layer comprising a second conductive material having a second Seebeck coefficient, the second Seebeck coefficient being different from the first Seebeck coefficient; and a plurality of vias located between the first conductive layer and the second conductive layer; and a sensing circuit coupled to the thermopile and configured to measure a voltage proportional to a temperature gradient between a first end and a second end of the flexible PCB coupled to the rigid PCB; and a processing circuit coupled to the sensing circuit and the absolute temperature sensor, the processing circuit being configured to estimate a second temperature using the first temperature and the signal proportional to the temperature gradient. Alternatively or alternatively, in some examples, the absolute temperature sensor includes: a negative temperature coefficient (NTC) temperature sensor, a resistance temperature detector (RTD), or a diode-based temperature sensor. Alternatively or alternatively, in some examples, the electronic device further includes a housing; wherein the absolute temperature sensor is disposed within the housing and configured to estimate the first temperature at a first location within the housing. Alternatively or alternatively, in some examples, the electronic device is a wearable device, and the second temperature is the skin temperature at the contact point between the user's skin and the wearable device. Alternatively or alternatively, in some examples, the second temperature is the ambient temperature outside the electronic device. Alternatively or alternatively, in some examples, the first temperature corresponds to a first location within the electronic device, and the second temperature corresponds to a second location within the electronic device, the second location being different from the first location. Alternatively or alternatively, in some examples, the second location is the back crystal of the electronic device. Alternatively or alternatively, in some examples, the second location is a second rigid PCB of the electronic device. Alternatively or alternatively, in some examples, the electronic device further includes an optical sensor comprising: one or more photoemitters; and one or more photodetectors; and wherein the first end or the second end of the flexible PCB is coupled to the optical sensor. Alternatively or alternatively, in some examples, the one or more photoemitters and the one or more photodetectors are coupled to the rigid PCB.Alternatively or in some examples, the one or more photoemitters and the one or more photodetectors are coupled to a second PCB of the electronic device, the first end of the flexible PCB is coupled to the second rigid PCB, and the second end of the flexible PCB is coupled to the rigid PCB.

[0190] Some examples involve a method comprising: measuring a first temperature at a first location using an absolute temperature sensor; estimating a heat flux across a flexible printed circuit board, the flexible printed circuit board including a first conductive layer having a first conductive material, a second conductive layer having a second conductive material, and a plurality of vias, the first conductive material having a first Seebeck coefficient, the second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient, the plurality of vias interconnecting segments of the first conductive material and segments of the second conductive material to form a thermopile; and estimating a second temperature at a second location different from the first location. Additionally or alternatively, in some examples, estimating the heat flux across the flexible printed circuit board includes: measuring a differential voltage across the thermopile; and estimating the heat flux using the differential voltage, the thermal resistance of the flexible printed circuit board, and the thermoelectric sensitivity of the thermopile. Additionally or alternatively, in some examples, the second temperature is a skin temperature at a contact point between a user's skin and an electronic device including the flexible printed circuit board. Additionally or alternatively, in some examples, the second temperature is an ambient temperature outside the electronic device including the flexible printed circuit board.

[0191] Some examples of this disclosure relate to: using an absolute temperature sensor to measure a first temperature at a first location; estimating a temperature difference across a flexible printed circuit board (PCB) including a thermopile; estimating a second temperature at a second location corresponding to the first light emitter, different from the first location; and estimating the wavelength of light emitted from the first light emitter based on the second temperature. Additionally or alternatively, in some examples, the method further includes adjusting drive parameters of the first light emitter based on the estimated wavelength of light emitted from the first light emitter. Additionally or alternatively, in some examples, adjusting the drive parameters includes adjusting a drive current applied to the first light emitter. Additionally or alternatively, in some examples, the method includes compensating for an estimate of the physiological characteristics of light detected by a photodetector based on the estimated wavelength of light emitted from the first light emitter. Additionally or alternatively, in some examples, the method includes: estimating a second temperature difference across a second flexible printed circuit board (PCB) including a second thermopile; estimating a third temperature at a third location corresponding to the second light emitter, different from both the first and second locations; and estimating the wavelength of light emitted from the second light emitter based on the second temperature. Additionally or alternatively, in some examples, the method includes adjusting the driving parameters of the first light emitter based on an estimated wavelength of light emitted from the first light emitter and / or adjusting the driving parameters of the second light emitter based on an estimated wavelength of light emitted from the second light emitter; and / or compensating for estimates of the physiological characteristics of light detected by one or more photodetectors based on the estimated wavelength of light emitted from the first light emitter and / or based on the estimated wavelength of light emitted from the second light emitter. Additionally or alternatively, in some examples, the flexible PCB further includes a second thermopile, and the method further includes: using the second thermopile to estimate a second temperature difference across the flexible PCB; estimating a third temperature corresponding to a third location of the second light emitter that differs from the first and second locations; and estimating the wavelength of light emitted from the second light emitter based on the second temperature. Additionally or alternatively, in some examples, the method includes adjusting the driving parameters of the first light emitter based on an estimated wavelength of light emitted from the first light emitter and / or adjusting the driving parameters of the second light emitter based on an estimated wavelength of light emitted from the second light emitter; and / or compensating for estimates of the physiological characteristics of light detected by one or more photodetectors based on the estimated wavelength of light emitted from the first light emitter and / or based on the estimated wavelength of light emitted from the second light emitter.Alternatively or concurrently, in some examples, the flexible PCB includes a first conductive layer having a first conductive material, a second conductive layer having a second conductive material, and a plurality of vias, the first conductive material having a first Seebeck coefficient, the second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient, the plurality of vias interconnecting segments of the first conductive material and segments of the second conductive material to form the thermopile. It should be noted that the wavelength estimation techniques disclosed herein can be applied to any LED / PD (e.g., a light-emitting diode / photodetector or photodiode component located anywhere in the device).

[0192] Some examples of this disclosure relate to a first photoelectric emitter; a first photodetector; a first flexible printed circuit board (PCB) including a first thermopile; optical circuitry configured to drive the first photoelectric emitter and measure the first photodetector; an absolute temperature sensor configured to estimate a first temperature; a thermopile sensing circuitry coupled to the first thermopile and configured to measure a signal (such as an electrical characteristic, such as a voltage signal, or another type of signal) proportional to a temperature gradient between a first end and a second end of the first flexible PCB; and processing circuitry coupled to the thermopile sensing circuitry and the absolute temperature sensor, the processing circuitry being configured to: estimate a second temperature at the first photoelectric emitter using the first temperature estimate and the signal proportional to the temperature gradient between the first end and the second end of the first flexible PCB; and estimate the wavelength of light emitted by the first photoelectric emitter. Additionally or alternatively, in some examples, the processing circuitry is further configured to: adjust the driving parameters of the first photoelectric emitter using the estimated wavelength of the light emitted from the first photoelectric emitter. Alternatively or additionally, in some examples, adjusting the driving parameters includes adjusting the driving current applied to the first photoemitter. Alternatively or additionally, in some examples, the processing circuitry is further configured to compensate for an estimate of the physiological characteristics of the light detected by the photodetector based on the estimated wavelength of the light emitted from the first photoemitter. Alternatively or additionally, in some examples, the optical circuitry, the absolute temperature sensor, the thermopile sensing circuitry, and the processing circuitry are integrated in an integrated circuit. Alternatively or additionally, in some examples, the first photoemitter and the first photodetector are disposed on the first flexible PCB at a second end of the first flexible PCB. Alternatively or additionally, in some examples, the first flexible PCB includes routing traces configured to route the first photoemitter and the first photodetector to the optical circuitry.Additionally or alternatively, in some examples, the electronic device further includes: a second photoelectric emitter; a second photodetector; a second flexible PCB, the second flexible PCB including a second thermopile; wherein: the optical circuitry is further configured to drive the second photoelectric emitter and measure the second photodetector; the thermopile sensing circuitry is coupled to the second thermopile and configured to measure a signal (such as an electrical characteristic, such as a voltage signal, or another type of signal) proportional to a temperature gradient between a first end and a second end of the second flexible PCB; and the processing circuitry is further configured to: estimate a third temperature at the second photoelectric emitter using the first temperature estimate and the signal proportional to the temperature gradient between the first end and the second end of the second flexible PCB; and estimate the wavelength of light emitted by the second photoelectric emitter. Additionally or alternatively, in some examples, the second photoelectric emitter and the second photodetector are disposed on the second flexible PCB at the second end of the second flexible PCB. Additionally or alternatively, in some examples, the electronic device further includes: a second photoelectric emitter; a second photodetector; wherein: the first flexible PCB further includes a second thermopile; the optical circuitry is further configured to drive the second photoelectric emitter and measure the second photodetector; the thermopile sensing circuitry is coupled to the second thermopile and configured to measure a signal (such as an electrical characteristic, such as a voltage signal, or another type of signal) proportional to the temperature gradient between a first end and a second end of the first flexible PCB; and the processing circuitry is further configured to: estimate a third temperature at the second photoelectric emitter using the first temperature estimate and the signal proportional to the temperature gradient between the first end and the second end of the first flexible PCB; and estimate the wavelength of the light emitted by the second photoelectric emitter. Alternatively or alternatively, in some examples, the first thermopile includes a plurality of thermocouples connected in series, and the first flexible PCB includes: a first conductive layer comprising a first conductive material having a first Seebeck coefficient; a second conductive layer comprising a second conductive material having a second Seebeck coefficient, the second Seebeck coefficient being different from the first Seebeck coefficient; and a plurality of vias located between the first conductive layer and the second conductive layer. Alternatively or alternatively, in some examples, the electronic device is a wearable device.

[0193] Some examples relate to a method comprising: monitoring one or more first sensors; estimating a user's body temperature based on determining that one or more criteria are met, wherein estimating the user's body temperature comprises: measuring a first temperature at a first location within an electronic device using an absolute temperature sensor; estimating a temperature difference across a flexible printed circuit board (PCB) including a thermopile; and estimating a second temperature at a second location different from the first location; and abandoning the estimation of the user's body temperature based on determining that the one or more criteria are not met. Additionally or alternatively, in some examples, the one or more first sensors include touch sensors, and the one or more first criteria include criteria met when an object touches the touch sensor. Additionally or alternatively, in some examples, the one or more first sensors include touch sensors, and the one or more first criteria include criteria met when an object touches a region greater than a threshold area of ​​the touch sensor. Additionally or alternatively, in some examples, the one or more first sensors include motion and / or orientation sensors. Additionally or alternatively, in some examples, the motion and / or orientation sensors include inertial measurement units, accelerometers, or gyroscopes. Additionally or alternatively, in some examples, the one or more first criteria include a criterion that is met when the motion and / or orientation sensor indicates less than a threshold amount of motion. Additionally or alternatively, in some examples, the one or more first criteria include a criterion that is met when the motion and / or orientation sensor indicates movement of the user's wrist toward the user's forehead. Additionally or alternatively, in some examples, the one or more first sensors include the absolute temperature sensor and / or the thermopile, and wherein the one or more first criteria include an absolute temperature above a first temperature threshold and / or a temperature difference above a second temperature threshold.

[0194] Some examples relate to an electronic device comprising: an absolute temperature sensor configured to estimate a first temperature at a first location within the electronic device; a flexible PCB including a thermopile; a sensing circuit coupled to the thermopile and configured to measure a voltage proportional to a temperature gradient across the thermopile; and a processing circuit coupled to the sensing circuit and the absolute temperature sensor, the processing circuit being configured to: monitor one or more of the first sensors; estimate a user's body temperature based on determining that one or more criteria are met, wherein estimating the user's body temperature includes: using the absolute temperature sensor to measure the first temperature at the first location; estimating a temperature difference across the thermopile; and estimating a second temperature at a second location different from the first location; and abandoning the estimation of the user's body temperature based on determining that the one or more criteria are not met.

[0195] Some examples of this disclosure relate to a method comprising: monitoring one or more first sensors; estimating a user's body temperature based on determining that one or more criteria are met, wherein estimating the user's body temperature comprises: measuring a first temperature at a first location within an electronic device using an absolute temperature sensor; estimating a temperature difference across a flexible printed circuit board (PCB) including a thermopile; estimating a second temperature at a second location different from the first location; and abandoning the estimation of the user's body temperature based on determining that the one or more criteria are not met.

[0196] Alternatively or alternatively, in some examples, the one or more first sensors include a touch sensor, and the one or more criteria include a criterion that is met when an object touches the touch sensor. Alternatively or alternatively, in some examples, the one or more first sensors include a touch sensor, and the one or more criteria include a criterion that is met when an object contacts a region greater than a threshold area of ​​the touch sensor. Alternatively or alternatively, in some examples, the one or more first sensors include a motion and / or orientation sensor. Alternatively or alternatively, in some examples, the motion and / or orientation sensor includes an inertial measurement unit, an accelerometer, or a gyroscope. Alternatively or alternatively, in some examples, the one or more criteria include a criterion that is met when the motion and / or orientation sensor indicates a motion amount less than a threshold. Alternatively or alternatively, in some examples, the one or more criteria include a criterion that is met when the motion and / or orientation sensor indicates a motion of the user's wrist toward the user's forehead. Alternatively or alternatively, in some examples, the one or more first sensors include the absolute temperature sensor and / or the thermopile, and wherein the one or more criteria include an absolute temperature above a first temperature threshold and / or a temperature difference above a second temperature threshold.

[0197] Some examples of this disclosure relate to an electronic device comprising: an absolute temperature sensor configured to estimate a first temperature at a first location within the electronic device; a flexible PCB including a thermopile; a sensing circuit coupled to the thermopile and configured to measure a voltage proportional to a temperature gradient across the thermopile; and a processing circuit coupled to the sensing circuit and the absolute temperature sensor, the processing circuit being configured to: monitor one or more of the first sensors; estimate a user's body temperature based on determining that one or more criteria are met, wherein estimating the user's body temperature includes: using the absolute temperature sensor to measure the first temperature at the first location; estimating a temperature difference across the thermopile; and estimating a second temperature at a second location different from the first location; and abandoning the estimation of the user's body temperature based on determining that the one or more criteria are not met.

[0198] Some examples of this disclosure relate to a method comprising: receiving a request to initiate a temperature measurement at a device; initiating the temperature measurement based on determining that one or more criteria are met; and, based on determining that the one or more criteria are not met: implementing one or more measures at the device to meet the one or more criteria; and initiating the temperature measurement after the one or more measurements are implemented.

[0199] Alternatively or additionally, in some examples, the one or more criteria include criteria based on operating conditions associated with the device, and the method further includes: based on determining that the one or more criteria are met: in response to initiating the temperature measurement, monitoring the operating conditions associated with the device; and compensating the temperature measurement based on the operating conditions. Alternatively or additionally, in some examples, compensating the temperature measurement based on the operating conditions includes: generating an adjusted temperature measurement by applying a temperature compensation model based on the operating conditions to the temperature measurement. Alternatively or additionally, in some examples, the temperature compensation model is based on power draw associated with the device condition, and the method further includes: displaying the adjusted temperature measurement. Alternatively or additionally, in some examples, implementing the one or more measures includes: instructing a user to adjust the orientation of the device relative to the user's skin. Alternatively or additionally, in some examples, implementing the one or more measures includes: instructing a user to reduce the movement of the device. Alternatively or additionally, in some examples, implementing the one or more measures includes: instructing a user to modify their interaction with the device to minimize the use of device components associated with heat dissipation. Additionally or alternatively, in some examples, implementing the one or more measures includes: suppressing power delivery to device components associated with heat dissipation at the device. Additionally or alternatively, in some examples, the device components associated with heat dissipation include a processor, display, antenna, cellular communication circuitry, Wi-Fi circuitry, Bluetooth circuitry, or GPS circuitry. Additionally or alternatively, in some examples, the method further includes: performing the temperature measurement; and, in response to performing the temperature measurement, resuming power delivery to the device components associated with heat dissipation. Additionally or alternatively, in some examples, implementing the one or more measures includes: changing the operating mode of the device to a lower power mode associated with lower heat dissipation.

[0200] Some examples relate to an electronic device that includes any of the heat flux sensors described above.

[0201] Some examples of this disclosure relate to a non-transitory computer-readable storage medium that stores instructions that, when executed by an electronic device including processing circuitry, cause the device to perform any of the methods described above.

[0202] This disclosure assumes that entities responsible for collecting, analyzing, disclosing, transmitting, storing, or otherwise using such personal data will comply with established privacy policies and / or privacy practices. Specifically, such entities should implement and adhere to privacy policies and practices that are recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy and security of personal data. Such policies should be easily accessible to users and should be updated as data collection and / or use change. Personal information from users should be collected for the entity's lawful and reasonable purposes and not shared or sold outside of these lawful uses. Furthermore, such collection / sharing should require the user's informed consent. In addition, such entities should consider taking any necessary steps to protect and safeguard access to such personal data and ensure that others with access to personal data comply with their privacy policies and processes. Additionally, such entities may be subject to third-party evaluations to demonstrate their compliance with widely accepted privacy policies and practices. These policies and practices may be tailored to geographic regions and / or the specific type and nature of the personal data collected and used.

[0203] Regardless of the foregoing, this disclosure also envisions examples of users selectively blocking the collection, use, or access to personal data, including physiological information. For example, users might be able to disable hardware and / or software components that collect physiological information. Additionally, this disclosure anticipates providing hardware and / or software components to prevent or block access to collected personal data. Specifically, users may have the option to remove, disable, or restrict access to certain health-related applications that collect their personal health or fitness data.

[0204] While the disclosed examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. It should be understood that such changes and modifications are considered to be included within the scope of the disclosed examples as defined by the appended claims.

Claims

1. An electronic device, comprising: An absolute temperature sensor is configured to estimate a first temperature; Post-crystal; An optical sensor, comprising one or more photoelectric emitters and one or more photoelectric detectors; as well as Heat flux sensor, including: A printed circuit board (PCB) includes an optical spacer between the optical sensor and the back crystal of the electronic device, and the PCB includes a thermopile, wherein the thermopile includes a plurality of thermocouples connected in series. The PCB has a plurality of vias, the plurality of vias including one or more first vias from a first layer to a second layer of the PCB and one or more second vias from the first layer to the second layer of the PCB, the one or more first vias including a first conductive material having a first Seebeck coefficient, and the one or more second vias including a second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient; Multiple conductive traces, the multiple conductive traces being on a first layer of the PCB and also on a second layer of the PCB, the multiple conductive traces interconnecting the multiple vias; and A sensing circuit coupled to the thermopile and configured to measure a voltage proportional to the temperature gradient between the first and second layers of the PCB; and The processing circuitry is configured to use the voltage and the first temperature, which are proportional to the temperature gradient, to estimate a second temperature at the optical sensor and / or at the rear crystal.

2. The electronic device of claim 1, wherein each of the plurality of thermocouples includes a through-hole in the first through-hole and a through-hole in the second through-hole, coupled through one of the plurality of conductive traces.

3. The electronic device of claim 1, wherein the plurality of vias includes through-holes passing through the first layer and the second layer.

4. The electronic device according to claim 1, wherein: The PCB includes a third layer and a fourth layer, with the first layer and the second layer located between the third layer and the fourth layer; and The plurality of through holes includes embedded through holes.

5. The electronic device according to claim 1, wherein: The PCB includes a third layer and a fourth layer, wherein the first layer and the second layer are located above the third layer and the fourth layer, or the first layer and the second layer are located below the third layer and the fourth layer; and The plurality of through holes includes blind through holes.

6. The electronic device of claim 1, wherein the sensing circuit is mounted on the surface of the PCB.

7. The electronic device according to claim 1, wherein the first Seebeck coefficient is a positive Seebeck coefficient and the second Seebeck coefficient is a negative Seebeck coefficient.

8. The electronic device according to claim 1, wherein the first conductive material is copper and the second conductive material is constantan.

9. The electronic device of claim 1, wherein the PCB has a thickness of more than 300 micrometers.

10. The electronic device of claim 1, wherein the PCB has a thickness greater than 1 mm.

11. The electronic device of claim 1, wherein the first temperature corresponds to a first position within the electronic device, and the second temperature corresponds to a second position within the electronic device, the second position being different from the first position.

12. The electronic device of claim 11, wherein the second position is separated from the first position by the PCB such that the second position is separated from the first position across at least the thickness of the PCB.

13. The electronic device according to claim 1, further comprising: A display, the display including a second PCB.

14. The electronic device of claim 1, wherein the processing circuitry is further configured to estimate physiological characteristics using the wavelength of at least one of the optical sensor and the one or more photoelectric emitters.

15. A method for estimating temperature, the method comprising: In an electronic device that includes an absolute temperature sensor and an optical sensor, the optical sensor includes one or more photoelectric emitters and one or more photodetectors: Use an absolute temperature sensor to measure the first temperature at the first location; Estimating the heat flux through a printed circuit board (PCB), the PCB including an optical spacer between the optical sensor and the back crystal of the electronic device, and further including a plurality of vias, the plurality of vias including one or more first vias from a first layer to a second layer of the PCB, the one or more first vias including a first conductive material having a first Seebeck coefficient, the plurality of vias also including one or more second vias, the one or more second vias including a second conductive material having a second Seebeck coefficient different from the first Seebeck coefficient, wherein the plurality of vias are interconnected to form a thermopile; as well as The first temperature and the estimated heat flux are used to estimate a second temperature at a second location different from the first location, the second location corresponding to the optical sensor and / or the rear crystal.

16. The method of claim 15, wherein estimating the heat flux through the printed circuit board comprises: Measure the differential voltage across the thermopile; as well as The heat flux is estimated using the differential voltage, the thermal resistance of the printed circuit board, and the thermoelectric sensitivity of the thermopile.

17. The method of claim 15, wherein the second temperature measurement is the skin temperature at the contact point between the user's skin and the electronic device including the printed circuit board.

18. The method of claim 15, wherein the first location is within the electronic device including the printed circuit board, and the second location is within the electronic device, the second location being separated from the first location by the printed circuit board such that the second location is separated from the first location across at least the thickness of the printed circuit board.

19. The method of claim 15, further comprising: Physiological characteristics are estimated using the wavelength of at least one of the optical sensor and the one or more photoelectric emitters.

20. The method of claim 15, wherein the PCB has a thickness greater than 300 micrometers.

Images