Light emitting device driving circuit, PPG sensor and electronic device

Abstract

This application provides a light-emitting device driving circuit, a PPG sensor, and an electronic device, relating to the field of electronic devices, capable of detecting abnormal light emission from a light-emitting device. The light-emitting device driving circuit includes: a voltage conversion circuit, a light-emitting component, a current driving circuit, a light-emitting control circuit, and a detection circuit; any light-emitting device in the light-emitting component and the current driving circuit are connected in series between the output terminal of the voltage conversion circuit and the ground terminal; the light-emitting control circuit is configured to: output a light-emitting control signal to the current driving circuit; the current driving circuit is configured to: provide current to at least one light-emitting device according to the light-emitting control signal; the detection circuit is configured to: detect the light-emitting control signal and generate a detection signal, wherein the detection circuit or a system chip connected to the detection circuit determines that the light-emitting component is abnormally emitting based on the detection signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic devices, and in particular to a light-emitting device driving circuit, a photoplethysmograph (PPG) sensor, and an electronic device. BACKGROUND

[0002] Currently, light-emitting devices such as laser diodes (LDs) or light emitting diodes (LEDs) are widely used in electronic devices. Generally, light-emitting devices are mainly used in electronic devices for functions such as display backlight, measurement (e.g., distance, biological characteristics of the human body, etc.), signal indication, illumination, etc. For example, a photoplethysmograph (PPG) sensor mainly emits a test light signal by driving a light-emitting device, a portion of the test light signal is reflected inside the skin or at the skin interface, and a portion of the test light signal is scattered inside the skin. A portion of the scattered light signal returns to the PPG sensor and is received by a detector of the PPG sensor. This portion of the scattered signal is referred to as a backscattered signal. In addition to being able to receive a portion of the scattered signal, the detector also receives a portion of the reflected signal. Through the backscattered signal or the reflected signal, the human body can be continuously measured, and data such as heart rate and blood oxygen can be collected.

[0003] However, abnormal control of the light-emitting device can further cause the light-emitting device to abnormally emit light, which can in turn cause abnormal detection of data by the PPG sensor. In some cases, the abnormal light intensity can also cause skin irritation in users. Therefore, how to detect abnormal light emission of the light-emitting device becomes a key to further improve the function of the device. SUMMARY

[0004] Embodiments of the present application provide a light-emitting device driving circuit, a photoplethysmograph (PPG) sensor, and an electronic device, which can detect abnormal light emission of the light-emitting device.

[0005] To achieve the above object, the present application adopts the following technical solutions:

[0006] In a first aspect, a light emitting device driving circuit is provided, comprising: a voltage conversion circuit, a light emitting component, a current driving circuit, a light emitting control circuit and a detection circuit; any light emitting device in the light emitting component and the current driving circuit are connected in series between an output terminal and a ground terminal of the voltage conversion circuit; the light emitting control circuit is configured to output a light emitting control signal to the current driving circuit; the current driving circuit is configured to provide a current to at least one light emitting device according to the light emitting control signal; and the detection circuit is configured to detect the light emitting control signal and generate a detection signal, wherein the detection circuit or a system chip connected with the detection circuit determines that the light emitting component abnormally emits light according to the detection signal. In this way, when the light emitting control circuit controls the current driving circuit to output a current to at least one light emitting device in the light emitting component through the light emitting control signal to drive the light emitting device to emit light, the detection circuit can detect the light emitting control signal and generate a detection signal; then, the detection circuit or a controller connected with the detection circuit can determine that the light emitting component abnormally emits light according to the detection signal, thereby realizing detection of abnormal light emission of the light emitting component.

[0007] In a possible implementation, the current driving circuit comprises a current source and a switching switch circuit; a common terminal of the switching switch circuit is coupled with the current source, and any light emitting device is coupled with any selection terminal of the switching switch circuit; the light emitting control signal comprises a switching control signal and a current control signal; the switching switch circuit is configured to couple the common terminal with a selection terminal coupled with a first light emitting device to turn on in at least one light emitting period, so as to couple the current source with the first light emitting device; the current source is configured to provide a current to the first light emitting device according to the current control signal; and the detection circuit is configured to generate the detection signal according to an accumulated value of the current control signal corresponding to the first light emitting device in a first time period, wherein when the accumulated value exceeds a judgment threshold value, it is determined that the light emitting component abnormally emits light, and the first light emitting device continuously emits light in the light emitting period. In this scheme, the detection circuit can detect any light emitting device (Dg, Dr and Dir) in the first time period.

[0008] In one possible implementation, the first time period comprises at least one detection period, and each detection period comprises at least one light emitting period. In this scheme, the detection circuit can detect any light emitting device (Dg, Dr, and Dir) in one or more light emitting periods; or the detection circuit can detect any light emitting device (one of Dg, Dr, and Dir) in one or more detection periods, and it is noted that the first light emitting device can be any one of Dg, Dr, and Dir, and then the detection can be performed for one or more detection periods (e.g., a pulse repetition frequency (PRF) period), and one detection period comprises one or more light emitting periods of any one of Dg, Dr, and Dir.

[0009] In a possible implementation, the current driving circuit includes a current source and a switching circuit; a common terminal of the switching circuit is coupled with the current source, and any of the light emitting devices is coupled with a selection terminal of the switching circuit; the light emitting control signal includes a switching control signal and a current control signal; the switching circuit is configured to: according to the switching control signal, in at least one light emitting period of the first light emitting device, turn on the selection terminal coupled with the first light emitting device to couple the current source with the first light emitting device; or, according to the switching control signal, in at least one light emitting period of the second light emitting device, turn on the selection terminal coupled with the second light emitting device to couple the current source with the second light emitting device; the current source is configured to: when the current source is coupled with the first light emitting device, provide a current to the first light emitting device according to the current control signal, and when the current source is coupled with the second light emitting device, provide a current to the second light emitting device according to the current control signal; and the detection circuit is configured to generate the detection signal according to the accumulated value of the current control signal corresponding to the first light emitting device and the second light emitting device in the first time period, wherein when the accumulated value exceeds a judgment threshold, it is determined that the light emitting assembly is abnormally emitting, wherein the first time period includes at least one detection period, one detection period includes at least one light emitting period of the first light emitting device and at least one light emitting period of the second light emitting device, and the first light emitting device continuously emits light in one light emitting period of the first light emitting device, and the second light emitting device continuously emits light in one light emitting period of the second light emitting device. In this scheme, the detection circuit can detect at least one light emitting device (for example: two or more of Dg, Dr and Dir) in the first time period (for example: one or more detection periods, or any configured time period). The detection period can be a PPG sensor PRF period, and one detection period includes one or more light emitting periods of each light emitting device in Dg, Dr and Dir, for example, when the light emitting assembly includes two light emitting devices, the first light emitting device continuously emits light in one light emitting period of the first light emitting device, and the second light emitting device continuously emits light in one light emitting period of the second light emitting device.

[0010] In a possible implementation, the controller is configured to generate the judgment threshold according to the maximum accumulated value detected in a second time period. For example, the second time period can be any time period before the first time period, and the second time period can be the same length as the first time period, for example, the maximum accumulated value is detected in the second time period first after starting detection, and the maximum accumulated value is taken as the judgment threshold, and then in the subsequent detection process, the accumulated value detected in the first time period is compared with the judgment threshold.

[0011] In a possible implementation, the controller is configured to generate the judgment threshold according to a maximum of the accumulated values detected in a second time period, and increase or decrease a predetermined offset.

[0012] In a possible implementation, the controller is configured to obtain an electrical parameter of the light emitting device by looking up a table, and calculate the judgment threshold according to the electrical parameter of the light emitting device, wherein the table contains a correspondence between the electrical parameter of the light emitting device and the light emitting device, and the electrical parameter includes a maximum current control signal of the light emitting device in one light emitting period.

[0013] In a possible implementation, the controller is configured to obtain the judgment threshold by looking up a table, and the table contains a correspondence between an electrical parameter of the light emitting device and the judgment threshold, and the electrical parameter includes a current transfer ratio of the light emitting device and the photodetector.

[0014] In a possible implementation, the controller is configured to calculate the judgment threshold by a predetermined formula, and the predetermined formula is expressed as Pth=k×CTR+B, where CTR is a current transfer ratio of the light emitting device and the photodetector, k and B are constants, and Pth is the judgment threshold.

[0015] In a possible implementation, the controller is configured to determine the judgment threshold according to a working scenario, and the working scenario includes at least one of the following: a standby scenario, a sleep scenario, and a motion scenario. For example, a higher judgment threshold can be set in the motion scenario, and a lower judgment threshold can be set in the sleep scenario.

[0016] In a possible implementation, the light emitting device driving circuit further includes at least one control signal register and the controller, the light emitting control circuit is connected to the at least one control signal register, and the control signal register is connected to the controller; the light emitting control circuit is specifically configured to generate the light emitting control signal according to a control instruction configured by the controller in the at least one control signal register; and the controller is configured to reconfigure the control instruction when it is determined that the light emitting component emits abnormally.

[0017] In a possible implementation, the light emitting device driving circuit further includes a threshold register and the controller, the detection circuit is connected to the threshold register, the threshold register is connected to the controller, and the judgment threshold is stored in the threshold register; and the detection circuit is specifically configured to determine that the light emitting component emits abnormally according to the detection signal and a judgment threshold configured by the controller in the threshold register.

[0018] In a possible implementation manner, the light emitting device driving circuit comprises an analog frontend (AFE), and the AFE comprises a current driving circuit, a light emitting control circuit and a detection circuit.

[0019] In a possible implementation manner, the voltage conversion circuit comprises at least any one of a boost circuit, a buck-boost circuit.

[0020] In a second aspect, a PPG sensor is provided, comprising a photodetector and the light emitting device driving circuit according to the first aspect; wherein the photodetector is configured to detect a test light signal of the light emitting device reflected and / or scattered by a detected object.

[0021] In a third aspect, an electronic device is provided, comprising the light emitting device driving circuit according to the first aspect or the PPG sensor according to the second aspect.

[0022] The technical effects brought by any possible implementation manner of the second aspect and the third aspect can refer to the technical effects brought by the different implementation manners of the first aspect, which will not be described herein. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background art, the drawings needed to be used in the embodiments of the present application or the background art will be described below.

[0024] Figure 1A A top view of an electronic device provided by an embodiment of the present application;

[0025] Figure 1B A bottom view of an electronic device provided by an embodiment of the present application;

[0026] Figure 1C An internal structure diagram of an electronic device provided by an embodiment of the present application after the back cover is opened;

[0027] Figure 2 A working principle diagram of a PPG sensor provided by an embodiment of the present application;

[0028] Figure 3 A power supply mode diagram of a light emitting device provided by an embodiment of the present application;

[0029] Figure 4 A structure diagram of a light emitting device driving circuit provided by an embodiment of the present application;

[0030] Figure 5A structural schematic diagram of a light emitting device driving circuit is provided for another embodiment of the present application.

[0031] Figure 6 A structural schematic diagram of a light emitting device driving circuit is provided for another embodiment of the present application.

[0032] Figure 7 A structural schematic diagram of a light emitting device driving circuit is provided for another embodiment of the present application.

[0033] Figure 8 A structural schematic diagram of a light emitting device driving circuit is provided for another embodiment of the present application.

[0034] Figure 9 A structural schematic diagram of a light emitting device driving circuit is provided for another embodiment of the present application.

[0035] Figure 10 A signal timing diagram of a light emitting device driving circuit is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments can be a part of the embodiments of the present application, rather than all the embodiments of the present application.

[0037] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In the present application, “at least one” means one or more, and “multiple” means two or more. “And / or”, which describes the association relationship of the associated objects, means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, B exists alone, where A and B can be singular or plural. The character “ / ” generally represents an “or” relationship between the associated objects before and after it. “At least one of the following” or similar expressions means any combination of these items, including any combination of single item or multiple items. For example, at least one of a, b or c can represent a, b, c, a and b, a and c, b and c, or a, b and c, where a, b and c can be singular or plural. In addition, in the embodiments of the present application, “first”, “second”, etc. do not limit the quantity and order.

[0038] It should be noted that the terms "exemplary" and "for example" are used herein to mean "an example of" rather than "an ideal". Any embodiment or design solution described herein as "exemplary" or "for example" should not be construed as being more advantageous or superior than other embodiments or design solutions. Rather, the terms "exemplary" and "for example" are used to present concepts in a particular, concrete and simple manner. In this application, unless otherwise indicated and / or unless explicitly contradicted by context, the term "coupled" means any direct or indirect electrical connection by way of an electrical current signal transfer between devices.

[0039] The light emitting device driving circuit and the PPG sensor provided by the embodiments of the present application can be applied to electronic devices, such as mobile phones, tablet computers, personal computers (PCs), personal digital assistants (PDAs), smart watches, netbooks, wearable electronic devices, augmented reality (AR) devices, virtual reality (VR) devices, vehicle-mounted devices, smart cars, smart speakers, robots, smart glasses, and other types of terminals. The embodiments of the present application do not specially limit the specific forms of the above electronic devices.

[0040] Taking a mobile phone as an example, Figures 1A to 1C A structural schematic diagram of an electronic device 100 is shown, wherein, Figure 1A A top view of the electronic device 100 of the described embodiments is shown. Figure 1B A bottom view of the electronic device 100 of the described embodiments is shown. Figure 1C A structural schematic diagram of the internal structure of the electronic device 100 after the back cover is opened is shown, which shows a specific configuration of various internal components according to the described embodiments, Figure 1C The dashed arrow in indicates the direction in which the back cover is opened. It can be understood that the structure shown in the embodiments does not constitute a specific limitation on the electronic device 100. In other embodiments of the present application, the electronic device 100 can include more or fewer components than shown, or combine certain components, or split certain components, or different component arrangements.

[0041] As Figure 1A and Figure 1BAs shown, the electronic device 100 may include a housing 100A, which may include a front cover 101, a rear cover 103, and a frame 102. The front cover 101 and the rear cover 103 are disposed opposite to each other, and the frame 102 surrounds the front cover 101 and the rear cover 103, connecting them together. The front cover 101 may be a glass cover, and the display 192 is disposed below the front cover 101. The electronic device 100 may have input / output components arranged around the outer periphery of the housing 100A. For example, a hole 105A for a front-facing camera and a hole 106 for a receiver may be provided on the top of the front cover 101. A button 180 may be provided on one edge of the frame 102, and a microphone hole 107, a speaker hole 108, and a USB interface hole 109 may be provided on the bottom edge of the frame 102. A hole 105B for a rear-facing camera and a hole 105C for a PPG sensor may be provided on the top of the rear cover 103.

[0042] The housing 100A may have an interior cavity 104, within which internal components are encapsulated. For example... Figure 1CAs shown, the internal components can be housed within the cavity 104, the internal components can include a printed circuit board (PCB) 110, a speaker 170A for converting audio electrical signals into sound signals, a receiver 170B for converting audio electrical signals into sound signals, a microphone 170C for converting sound signals into electrical signals, a USB interface 130, a front camera 193A, a rear camera 193B, and a motor 191 for generating a vibration prompt, and the like. Among them, the printed circuit board 110 can be provided with a processor 120, a power management integrated circuit (PMIC) 140, at least one power amplifier (in an embodiment, including power amplifiers (PAs) 152A, 152B, 152C, 152D, different power amplifiers PA support different frequency bands, used to amplify transmission signals of different frequency bands, for example, power amplifiers PA 152A and 152B can be used to amplify transmission signals of a first bandwidth range, and power amplifiers PA 152C and 152D can be used to amplify transmission signals of a second bandwidth range), at least one envelope tracking modulator (ETM) for powering the power amplifier (in an embodiment, including envelope tracking modulators ETMs 151A and 151B, different envelope tracking modulators ETM support different bandwidths, for example, envelope tracking modulator ETM 151A powers power amplifiers PA 152A and 152B, and envelope tracking modulator ETM 151B powers power amplifiers PA 152C and 152D), a switching switch 153, and an antenna circuit 154, and the like. A PPG sensor 160, wherein the PPG sensor 160 includes a detector 161 and a light emitting device driving circuit 162; wherein the detector 161 is used to detect the test light signal of the light emitting device of the light emitting device driving circuit 162 reflected and / or scattered by the detected object. In addition, the printed circuit board 110 can also include filters, low-noise amplifiers, audio codecs, internal memories, sensors, inductors, capacitors, and the like. In order to clearly display the embodiment, the filters, low-noise amplifiers, audio codecs, internal memories, sensors, inductors, capacitors are not shown in the figure. Figure 1CThe components on the printed circuit board 110 are arranged closely to fit all the components in the limited space. The arrangement of the components on the printed circuit board 110 is not limited. In some embodiments, the components on the printed circuit board 110 can be arranged on one side of the printed circuit board 110 (e.g., the side facing the back cover 102). In some embodiments, the components on the printed circuit board 110 can be arranged on both sides of the printed circuit board 110 (e.g., on the side facing the back cover 102 and on the side facing the front cover 101, respectively).

[0043] The processor 120 can include one or more processing units, such as an application processor (AP), a modem processor, a graphics processing unit (GPU), an image signal processor (ISP), a neural-network processing unit (NPU), a controller, a video codec, a digital signal processor (DSP), a baseband, and / or a radio frequency circuit, etc. The controller can generate operation control signals according to instruction opcodes and timing signals to complete the control of fetching and executing instructions.

[0044] The processor 120 can include a memory for storing instructions and data. In some embodiments, the memory in the processor 120 is a cache memory. The memory can hold instructions or data that the processor 120 has just used or recycled. If the processor 120 needs to use the instructions or data again, it can directly call from the memory. This avoids repeated access and reduces the waiting time of the processor 120, thus improving the efficiency of the system.

[0045] The processor 120 can frequency-modulate a signal according to a mobile communication technology or a wireless communication technology. The mobile communication technology can include a global system for mobile communications (GSM), a general packet radio service (GPRS), a code division multiple access (CDMA), a wideband code division multiple access (WCDMA), a time-division code division multiple access (TD-SCDMA), a long term evolution (LTE), an emerging wireless communication technology (also referred to as a 5th generation mobile communication technology, English: 5th generation mobile networks or 5th generation wireless systems, 5th-Generation, 5th-Generation New Radio, 5G, 5G technology, or 5G NR), etc. The wireless communication technology can include a wireless local area network (WLAN) (such as a wireless fidelity (Wi-Fi) network), a bluetooth (BT), a global navigation satellite system (GNSS), a frequency modulation (FM), a near field communication (NFC), an infrared (IR) technology, etc.

[0046] The processor 120 can also include at least one baseband and at least one radio frequency circuit. The baseband refers to a circuit used to synthesize a baseband signal to be transmitted or / and to decode a received baseband signal. Specifically, when transmitting, the baseband encodes a voice or other data signal into a baseband signal (baseband code) to be transmitted; when receiving, the baseband decodes a received baseband signal (baseband code) into a voice or other data signal. The baseband can include components such as an encoder, a decoder, and a baseband processor. The encoder is used to synthesize a baseband signal to be transmitted, and the decoder is used to decode a received baseband signal. The baseband processor can be a microprocessor (MCU), which can be used to control the encoder and the decoder, for example, the baseband processor can be used to complete the scheduling of encoding and decoding, the communication between the encoder and the decoder, the driving of peripherals (which can be enabled by sending an enable signal to components outside the baseband), and the like. The radio frequency circuit is used to process the baseband signal to form a transmit (TX) signal and transmit the transmit signal to the power amplifier PA for amplification; or / and, the radio frequency circuit is used to process a receive (RX) signal to form a baseband signal and transmit the formed baseband signal to the baseband for decoding. In some embodiments, each baseband corresponds to a radio frequency circuit to frequency-modulate signals according to one or more communication technologies. For example, a first baseband and a first radio frequency circuit frequency-modulate signals according to a 5G technology, a second baseband and a second radio frequency circuit frequency-modulate signals according to a 4G technology, a third baseband and a third radio frequency circuit frequency-modulate signals according to a Wi-Fi technology, a fourth baseband and a fourth radio frequency circuit frequency-modulate signals according to a Bluetooth technology, and the like. Alternatively, a first baseband and a first radio frequency circuit can frequency-modulate signals according to both a 4G technology and a 5G technology, a second baseband and a second radio frequency circuit frequency-modulate signals according to a Wi-Fi technology, and the like. In some embodiments, a baseband can correspond to multiple radio frequency circuits to improve integration.

[0047] In some embodiments, the baseband and the radio frequency circuit can be integrated with other components of the processor 120 in an integrated circuit. In some embodiments, the baseband and the radio frequency circuit can be independent devices independent of the processor 120. In some embodiments, a baseband and a radio frequency circuit can be integrated in a device independent of the processor 120.

[0048] In the processor 120, different processing units can be independent devices or integrated in one or more integrated circuits.

[0049] The antenna circuit 154 is used to transmit and receive electromagnetic wave signals (radio frequency signals). Multiple antennas or multiple sets of antennas (a set of antennas includes more than two antennas) can be included in the antenna circuit 154, each of which can be used to cover a single or multiple communication frequency bands. The multiple antennas can be one or more of a multi-frequency antenna, an array antenna, or an on-chip antenna.

[0050] The processor 120 is coupled to the antenna circuit 154 to implement various functions associated with transmitting and receiving radio frequency signals. For example, when the electronic device 100 transmits a signal, the baseband synthesizes data (digital signals) to be transmitted into a baseband signal to be transmitted, the baseband signal is converted into a transmission signal (radio frequency signal) by the radio frequency circuit, the transmission signal is amplified by the power amplifier, the amplified output signal output by the power amplifier is transmitted to the switch 153, and the transmission signal is transmitted through the antenna circuit 154. The path of the transmission signal sent by the processor 120 to the switch 153 is the transmission link (or transmission path). When the electronic device 100 needs to receive a signal, the antenna circuit 154 transmits the received signal (radio frequency signal) to the switch 153, the switch 153 transmits the radio frequency signal to the radio frequency circuit, the radio frequency circuit processes the radio frequency signal into a baseband signal, and the radio frequency circuit converts the processed baseband signal into data and sends it to the corresponding application processor. The path of the radio frequency signal sent by the switch 153 to the processor 120 is the reception link (or reception path).

[0051] The switch 153 can be configured to selectively electrically connect the antenna circuit 154 to the transmission link or the reception link. In some embodiments, the switch 153 can include multiple switches. The switch 153 can also be configured to provide additional functions, including filtering and duplexing signals.

[0052] The SIM card interface 194 is configured to connect a SIM card. The SIM card can be connected to or disconnected from the electronic device 100 by being inserted into or pulled out of the SIM card interface 194. The electronic device 100 can support one or N SIM card interfaces, where N is a positive integer greater than one. The SIM card interface 194 can support Nano SIM cards, Micro SIM cards, SIM cards, and the like. Multiple cards can be inserted into the same SIM card interface 194. The types of the multiple cards can be the same or different. Each SIM card can support one or more communication standards, each of which has a specified frequency band and a different maximum bandwidth. The SIM card interface 194 can also be compatible with different types of SIM cards. The SIM card interface 194 can also be compatible with external memory cards. The electronic device 100 interacts with a network through the SIM card to implement functions such as call and data communication. In some embodiments, the electronic device 100 uses an eSIM, i.e., an embedded SIM card. The eSIM card can be embedded in the electronic device 100 and cannot be separated from the electronic device 100.

[0053] The PMIC 140 is configured to manage power in the electronic device 100. For example, the PMIC 140 can include a charging management circuit and a power supply management circuit. The charging management circuit is configured to receive a charging input from a charger, for example, in some embodiments of wired charging, the charging management circuit can receive a charging input from a wired charger through the USB interface 130. The power supply management circuit is configured to receive an input of the battery 141 and / or the charging management circuit, and supply power to the processor 120, the display 192, the front camera 193A, the rear camera 193B, and the motor 191, and the like. In other embodiments, the charging management circuit and the power supply management circuit can also be disposed in the processor 120. In other embodiments, the charging management circuit and the power supply management circuit can also be disposed in different devices.

[0054] Specific embodiments of the present application provide a light emitting device driving circuit including at least one light emitting device, which can be used in the PPG sensor described above. In combination with the light emitting device driving circuit, the PPG sensor can be used to detect the blood oxygen saturation of a user. Figure 2 As shown, the basic principle of the PPG sensor is that a test light signal is emitted by a light emitting device, a part of the test light signal is reflected at a detection object (e.g., inside the skin or the skin interface), and a part of the test light signal is scattered at the detection object (e.g., inside the skin). A part of the scattered signal will return to the PPG sensor and be received by a detector of the PPG sensor, which is referred to as a backscattered signal. In addition to receiving a part of the scattered signal, the detector also receives a part of the reflected signal.

[0055] Typically, PPG sensors emit light using multiple wavelengths, with each wavelength corresponding to a specific light-emitting device (e.g., laser diode (LD), light-emitting diode (LED), organic light-emitting diode (OLED), vertical-cavity surface-emitting laser (VCSEL), etc.). Of course, a single light-emitting device can also emit different wavelengths of light under different currents. For example, PPG sensors in wearable products generally use three wavelengths: green, red, and infrared (IR). The center wavelength of the green light emitter is typically 530nm, the red light emitter is typically 670nm, and the infrared light emitter is typically 850nm, 900nm, or 940nm.

[0056] Combination Figure 3 As shown, in electronic devices, a fixed voltage is typically supplied to the light-emitting device by a power supply, and the luminous intensity of the device is controlled by a current source that controls the current I flowing through it. Generally, increasing the current I increases the luminous intensity, while decreasing the current I decreases it. Taking LEDs (Dg, Dr, Dir; where Dg is a green LED, Dr is a red LED, and Dir is an infrared LED) as an example, in PPG sensors, LEDs are typically... Figure 4 The power supply and driving method are shown. The input terminal of the voltage conversion circuit 41 (e.g., the voltage conversion circuit 41 can be a boost circuit or a buck-boost circuit) is input with the system voltage (Vsys), and the output terminal Vout supplies power to one or more LEDs (Dg, Dr, Dir) of different wavelengths (e.g., connected to the anode of the LED). The cathode of the LED (Dg, Dr, Dir) is connected to the current driving circuit 42 (Tx Driver). The current driving circuit 42 generally includes a current source 422 and a switching circuit 421. When the current source 422 connects to the cathode of a certain LED (e.g., one of Dg, Dr, and Dir) through the switching circuit 421, the connected LED will emit light as current flows through it. The magnitude of the current provided by the current source 422 and the opening or closing of the switching circuit 421 are controlled by their respective control signals. For example, Figure 4As shown, the light emitting control circuit 43 can generate the above-mentioned control signal according to the control instruction of the controller 45 (for example, can be a system chip (SoC), a micro controller unit (MCU)). In some examples, the light emitting control circuit 43 and the current driving circuit 42 can be integrated in an analog front end (AFE) to be implemented, wherein the control instruction provided by the controller 45 can be stored in one or more registers provided by the AFE. However, the abnormal control of the light emitting device will further cause the abnormal light emission of the light emitting device, and then cause the abnormal detection of the PPG sensor data, especially in some cases, the abnormal light intensity will cause the skin allergy of the user. Therefore, how to realize the detection of the abnormal light emission of the light emitting device becomes the key to further improve the device function.

[0057] To solve the above-mentioned problems, the embodiment of the present application provides a light emitting device driving circuit, referring to Figure 5 As shown, comprising: a voltage conversion circuit 41, a light emitting assembly, a current driving circuit 42, a light emitting control circuit 43 and a detection circuit 44, wherein Figure 5 In the embodiment of the present application, the light emitting assembly takes at least one light emitting device (for example, LED (Dg, Dr, Dir)) as an example; any light emitting device (Dg, Dr, Dir) and the current driving circuit 42 are connected in series between the output end Vout of the voltage conversion circuit 41 and the ground end GND. It should be noted that in the embodiment of the present application, the series relationship of the light emitting device (Dg, Dr, Dir) and the current driving circuit 72 is not limited. For example, referring to Figure 5 As shown, one end of any light emitting device (Dg, Dr and Dir) is connected to the output end of the voltage conversion circuit 41, the other end of the light emitting device (Dg, Dr, Dir) is connected to one end of the current driving circuit 42, and the other end of the current driving circuit 42 is connected to the ground end GND. In Figure 6 In the embodiment of the present application, one end of the current driving circuit 42 is connected to the output end of the voltage conversion circuit 41, the other end of the one end of the current driving circuit 42 is connected to one end of any light emitting device (Dg, Dr and Dir), and the other end of the light emitting device (Dg, Dr and Dir) is connected to the ground end GND. Taking the LED as an example of the light emitting device, in Figure 5 In the example of the embodiment of the present application, the anode of the LED is connected to the output end of the voltage conversion circuit 41, and the cathode of the LED is connected to the current driving circuit 42; in Figure 6 In the example of the embodiment of the present application, the anode of the LED is connected to the current driving circuit 42, and the cathode of the LED is connected to the ground end GND.

[0058] The light emitting control circuit 43 is configured to output a light emitting control signal to the current driving circuit 42. The current driving circuit 42 is configured to provide a current to the at least one light emitting device according to the light emitting control signal. The detection circuit 44 is configured to detect the light emitting control signal and generate a detection signal. The detection circuit 44 or a controller 45 connected to the detection circuit 44 determines the abnormal light emitting of the light emitting assembly according to the detection signal. As shown in Figure 5 The light emitting control circuit 43 can generate the light emitting control signal according to the control instruction of the controller 45 (e.g., SoC or MCU) in some examples. In some examples, the light emitting control circuit 43, the detection circuit 44 and the current driving circuit 42 can be integrated in an AFE, and the control instruction provided by the controller 45 can be configured in one or more control signal registers provided by the AFE.

[0059] In this way, when the light emitting control circuit controls the current driving circuit to output a current to the at least one light emitting device through the light emitting control signal to drive the light emitting device to emit light, the detection circuit can detect the light emitting control signal and generate a detection signal. The detection circuit or the controller connected to the detection circuit can determine the abnormal light emitting of the light emitting assembly according to the detection signal, thereby realizing the detection of the abnormal light emitting of the light emitting device.

[0060] For example, referring to Figure 5 or Figure 6 The current driving circuit 42 includes a current source 422 and a switching circuit 421. The common terminal ct of the switching circuit 421 is coupled to the current source 422, and any of the light emitting devices (Dg, Dr and Dir) is coupled to any of the selection terminals of the switching circuit 421 (e.g., as shown in Figure 5 or Figure 6 The switching circuit 421 includes three selection terminals c1, c2 and c3, wherein the light emitting device Dg is coupled to the selection terminal c1, the light emitting device Dr is coupled to the selection terminal c2, and the light emitting device Dir is coupled to the selection terminal c3. The light emitting control signal includes a switching control signal and a current control signal. The switching circuit 421 is configured to couple the common terminal ct to the selection terminal coupled to the first light emitting device according to the switching control signal, so as to couple the current source 422 to the first light emitting device. For example, referring to Figure 7As shown, the light emitting control circuit 43 has a timing control function, when the switch control signal controls the switch circuit 421 to turn on the common terminal ct and the selection terminal c1 in at least one light emitting period, the current source 422 is coupled with the light emitting device Dg, for example, the switch control signal can be a pulse signal with a certain pulse width, and the common terminal ct and the selection terminal c1 can be turned on within the time length of the pulse width. Wherein, the switch control signal is synchronized with the lighting timing of the light emitting device Dg, that is, when the switch control signal controls the current source 422 to be coupled with the light emitting device Dg, the current source 422 is configured to provide a predetermined current to the light emitting device Dg according to the current control signal, and the light emitting device Dg is lit, for example, referring to Figure 7 As shown, the light emitting control circuit 43 has a dimming control function, and the light emitting device Dg is lit by sending a current control signal to the current source 422 to provide current to the light emitting device Dg. In another scheme, when the common terminal ct and the selection terminal c2 are turned on, the switch control signal is synchronized with the lighting timing of the light emitting device Dr, that is, when the switch control signal controls the current source 422 to be coupled with the light emitting device Dr in at least one light emitting period, the current source 422 is configured to provide a predetermined current to the light emitting device Dr according to the current control signal, and the light emitting device Dr is lit; for example, when the common terminal ct and the selection terminal c3 are turned on, the switch control signal is synchronized with the lighting timing of the light emitting device Dir, that is, when the switch control signal controls the current source 422 to be coupled with the light emitting device Dir in at least one light emitting period, the current source 422 is configured to provide a predetermined current to the light emitting device Dir according to the current control signal, and the light emitting device Dir is lit.

[0061] Wherein, in the scheme provided by the embodiment of the present application, the detection circuit 44 can detect the light emitting control signal in a first time period (for example, the first time period can include at least one light emitting period, or include at least one detection period (for example, the detection period can be a PRF period), or include a self-defined arbitrary time length) to generate a detection signal, and the process can be applied to the following scene.

[0062] Scenario one: the detection circuit 44 can detect any light emitting device (Dg, Dr and Dir) in at least one light emitting period (in which the any light emitting device continuously emits light), for example: the detection circuit 44 is configured to generate a detection signal according to the accumulated value of the current control signal of the first light emitting device in at least one light emitting period, wherein when the accumulated value exceeds the judgment threshold, it is determined that the light emitting assembly emits light abnormally, and in one light emitting period, the first light emitting device continuously emits light. Exemplarily, the light emitting period can be the time length of one continuous light emission of any light emitting device (Dg, Dr and Dir) in a pulse repetition frequency (PRF) period of the PPG sensor, wherein the PRF period includes a plurality of light emitting periods of the light emitting devices Dg, Dr and Dir in a predetermined order. It should be noted that the first light emitting device can be any one of Dg, Dr and Dir, and in this scenario one, detection can be performed for each light emitting period, which can be one or more light emitting time lengths (one light emitting time length is the pulse width of the switching control signal of any one of Dg, Dr and Dir) of any one of Dg, Dr and Dir, and the current control signal is the control value I of the current source dac For example, the accumulated value in one light emitting period can be represented as P i = I daci × T_PW i ; wherein T_PW i is the time length of the first light emitting device in the ith light emitting period, I daci is the control value of the current source of the first light emitting device in the ith light emitting period; in some examples, the accumulated value can also be represented as P i = V out × I daci × T_PW i , V out is the output voltage of the voltage conversion circuit 41. In some schemes, only the accumulated value of the current control signal of one light emitting device of one color of Dg, Dr and Dir in one light emitting period can be detected, and in other schemes, the accumulated value of the current control signal of one light emitting device of one color of Dg, Dr and Dir in two or more light emitting periods can also be detected. It should be noted that when detecting the accumulated value of the current control signal of one or more light emitting periods of different light emitting devices, different judgment thresholds can be set for different light emitting devices, and in scenario one, a corresponding detection circuit 44 can also be set for different light emitting devices to detect the accumulated value of the current control signal of one or more light emitting periods of the light emitting device.

[0063] Scenario two: the detection circuit 44 can detect any light emitting device (Dg, Dr and Dir) in at least one detection period, it should be noted that the first light emitting device can be any one of Dg, Dr and Dir, then in this scenario two, the detection period includes one or more light emitting periods of any one of Dg, Dr and Dir. For example: the detection circuit 44 is configured to generate a detection signal according to the cumulative value of the current control signal of the first light emitting device in at least one detection period, wherein when the cumulative value exceeds the judgment threshold, it is determined that the light emitting component is abnormal; one detection period includes at least one light emitting period of the first light emitting device, and the first light emitting device continuously emits light in one light emitting period. Exemplarily, the detection period can be one PRF period of the PPG sensor. Then the cumulative value can be represented as Wherein, T_PW i is the light emitting period of the first light emitting device in the i-th light emitting period in one detection period, I daci is the current control signal of the first light emitting device in the i-th light emitting period in one detection period, and m is the number of light emitting periods of the first light emitting device in one detection period; in some examples, the cumulative value can also be represented as V out is the output voltage of the voltage conversion circuit 41. Then in some schemes, only the cumulative value of the current control signal of the light emitting device of one color of Dg, Dr and Dir in one detection period can be detected, and in other schemes, the cumulative value of the current control signal of the light emitting device of one color of Dg, Dr and Dir in two or more detection periods can be detected. The difference from scenario one is that in scenario two, the detection circuit 44 can detect a light emitting device of a certain color in one detection period, such as one PRF period, and generate the cumulative value of the current control signal of the light emitting device of the certain color in the detection period as the detection signal, and the one detection period can include multiple light emitting periods. Similar to scenario one, in scenario two, when the cumulative value of the current control signal of the light emitting device in one detection period is detected, different judgment thresholds can be set for different light emitting devices, and in scenario two, the corresponding detection circuit 44 for detecting the cumulative value can also be set for different light emitting devices.

[0064] In a third scenario, the detection circuit 44 can detect at least one light emitting device (e.g., Dg, Dr, and Dir) in a first time period. For example, the detection circuit 44 is configured to generate a detection signal according to the accumulated value of the current control signals of the first light emitting device and the second light emitting device in the first time period, and determine that the light emitting assembly is abnormal when the accumulated value exceeds a judgment threshold. The first time period includes at least one detection period, and each detection period includes at least one light emitting period of the first light emitting device and at least one light emitting period of the second light emitting device. The first time period includes one or more light emitting periods of two or more of Dg, Dr, and Dir. For example, the first time period can be one or more detection periods (e.g., PRF periods) or any time period defined by the user. In the light emitting period of the first light emitting device, the first light emitting device emits light continuously, and in the light emitting period of the second light emitting device, the second light emitting device emits light continuously. Of course, the above only illustrates two light emitting devices, and in some examples, the detection of three light emitting devices at the same time is also possible. For example, in a detection period, Dg, Dr, and Dir are controlled to emit light, and in the third scenario, the detection can be performed for a first time period (e.g., a PRF period) including one or more light emitting periods of any one of Dg, Dr, and Dir in the PRF period. The accumulated value can be represented as where T_PW i is the light emitting period of the i-th light emitting device in a PRF period, I daci is the current control signal of the i-th light emitting device in a PRF period, and N is the number of light emitting devices in a PRF period. In some examples, the accumulated value can also be represented as V out is the output voltage of the voltage conversion circuit 41.

[0065] In addition, the setting method of the above-mentioned judgment threshold is specifically illustrated as follows:

[0066] In the first mode, the system chip is configured to generate the judgment threshold according to the maximum accumulated value detected in a second time period. For example, the second time period can be any time period before the first time period, and the second time period can have the same length as the first time period. For example, the maximum accumulated value can be detected in the second time period first after the detection starts, and the maximum accumulated value is taken as the judgment threshold, and then in the subsequent detection process, the accumulated value detected in the first time period is compared with the judgment threshold. For the above scenario one, the maximum accumulated value of the current control signal of the first light emitting device in one or more light emitting periods in a period of time can be detected, and the maximum accumulated value is taken as the judgment threshold. For example, the maximum accumulated value of the current control signal of the first light emitting device in one light emitting period can occur in a light emitting period with the maximum time length or in a light emitting period with the maximum current control signal. For example, the time length of each light emitting period is the same, and the maximum accumulated value of the current control signal of Dg in 10 min can be selected to generate the judgment threshold. Alternatively, the maximum accumulated value of the current control signal of Dg in a light emitting period with the maximum time length and the maximum current control signal. For example, in a period of time, the maximum time length T_PW i-max of the current control signal of the first light emitting device in the ith light emitting period is detected according to the switching control signal daci-max . Then, the judgment threshold can be represented as P th = I daci-max × T_PW i-max ; in some examples, the judgment threshold can also be represented as P th = V out × I daci-max × T_PW i-max , V out is the output voltage of the voltage conversion circuit 41. It should be noted that for different light emitting devices, the accumulated value of the current control signal in a light emitting period can be detected, and different judgment thresholds can be set for different light emitting devices according to the above mode. For the above scenario two, the maximum accumulated value of the current control signal of the first light emitting device in one or more detection periods in a period of time can be detected, and the maximum accumulated value is taken as the judgment threshold. For example, the maximum accumulated value of the current control signal of the first light emitting device in one detection period can occur in a detection period with the maximum light emitting period length, or in a detection period with the maximum current control signal, or in a detection period with the maximum light emitting period length and the maximum current control signal. For example, in a detection period in a period of time, the maximum time length T_PW i-max, the maximum control value of the current control signal of the first light emitting device in the i-th light emitting period daci-max ; the judgment threshold value can be represented as where N is the number of light emitting times of the first light emitting device in the detection period (i.e., the number of light emitting periods of the first light emitting device); in some examples, the judgment threshold value can also be represented as V out is the output voltage of the voltage conversion circuit 41. It should be noted that when detecting the cumulative value of the current control signal of different light emitting devices in the first time period, different judgment threshold values can be set for different light emitting devices according to the above-mentioned manner. For scenario three described above, the maximum cumulative value of the current control signal of multiple light emitting devices (e.g., Dg, Dr, and Dir) in the first time period (which can be one or more detection periods (e.g., PRF period)) can be detected in a period of time, and the maximum cumulative value is taken as the judgment threshold value. For example, the maximum cumulative value of the current control signal of multiple light emitting devices in a detection period can occur in a detection period in which the light emitting period of each light emitting device is the longest, or in a detection period in which the current control signal of each light emitting device is the largest, or in a detection period in which the light emitting period of each light emitting device is the longest and the current control signal of each light emitting device is the largest in the detection period. For example, in a detection period in a period of time, the maximum time length T_PW i-max , the maximum control value of the current control signal of the light emitting device in the i-th light emitting period daci-max ; the judgment threshold value can be represented as where M is the number of light emitting times of each light emitting device in the detection period (i.e., the number of light emitting periods of the light emitting devices (Dg, Dr, and Dir)); in some examples, the judgment threshold value can also be represented as V out is the output voltage of the voltage conversion circuit 41.

[0067] Method two: the system chip is configured to generate the judgment threshold value according to the detected maximum cumulative value by increasing or decreasing a predetermined offset. For example, the judgment threshold value P th determined in method one can be increased or decreased by a predetermined offset δp (P th ± δp).

[0068] The third way is that the system chip is configured to obtain the electrical parameter of the light emitting device by looking up a table, and to calculate the judgment threshold according to the electrical parameter of the light emitting device. The table contains the corresponding relationship between the electrical parameter of the light emitting device and the light emitting device, and the electrical parameter includes the maximum current control signal of the light emitting device in one light emitting period. For example, for the above-mentioned scene one and scene two, taking the light emitting device Dir as an example, the electrical parameter of the light emitting device can also include Dir's I daci-max , or the electrical parameter of Dri can also include Dir's I daci-max and T_PW i-max ; according to Dir's electrical parameter and the formula provided in scene one and scene two, P th is directly calculated. For scene three, Dir's I daci-max or Dri's I daci-max and T_PW i-max are obtained, and P th is directly calculated according to the electrical parameters of the multiple light emitting devices and the formula provided in scene three.

[0069] The fourth way is that the system chip is configured to obtain the judgment threshold by looking up a table, and the table contains the corresponding relationship between the electrical parameter of the light emitting device and the judgment threshold. The electrical parameter includes the current transfer ratio (CTR) of the light emitting device and the photodetector. For example, in a period of time, the light emitting device can be lit by driving the current source with a predetermined light emitting control signal, and the light intensity of the light emitting device can be detected by the photodetector to generate a detection current Ipd, wherein the predetermined light emitting control signal I dac and the current I ref provided by the current source to the light emitting device have a fixed proportional relationship. According to CTR = I ref / Ipd, CTR can be determined, and then the judgment threshold can be obtained by looking up the table according to CTR. It can be understood that, since different light emitting devices correspond to different CTRs in this way, the way of obtaining the judgment threshold by the fifth way is usually suitable for the above-mentioned scene one and scene two.

[0070] The fifth way is that the system chip is configured to calculate the judgment threshold by a predetermined formula, and the predetermined formula is Pth = k x CTR + B, CTR is the current transfer ratio of the light emitting device and the photodetector, k and B are constants, and the judgment threshold is Pth. After the CTR is obtained by referring to the way in the fourth way, the judgment threshold can be directly calculated according to the formula Pth = k x CTR + B. Since different light emitting devices correspond to different CTRs in this way, the way of obtaining the judgment threshold by the fifth way is usually suitable for the above-mentioned scene one and scene two.

[0071] The sixth mode: the system chip is configured to determine the judgment threshold according to the working scene, and the working scene at least includes any one of the following: standby scene, sleep scene, and motion scene. For example, a higher judgment threshold can be set in the motion scene, and a lower judgment threshold can be set in the sleep scene.

[0072] In the above examples, referring to Figure 8 , the light emitting device driving circuit further includes at least one control signal register and a controller, and the at least one control signal register can be connected to the light emitting control circuit 43 (for example, the pulse width control register, the current control register, the repetition frequency register, and other registers shown in Figure 8 ), and the control signal register is connected to the controller 45; the light emitting control circuit 43 is specifically configured to generate the light emitting control signal according to the control instruction configured by the controller 45 in the at least one control signal register; the controller 45 is configured to reconfigure the control instruction when it is determined that the light emitting component is abnormally emitting light. Specifically, the repetition frequency register is used to store the control instruction of the detection period (for example, the PRF period), the pulse width control register is used to store the control instruction of the light emitting period of the light emitting device, and the current control register is used to store the control instruction of the current control signal, for example, a control word in octal or hexadecimal can be used to map different currents.

[0073] In some examples, the light emitting control circuit 43 can also only report the detected detection signal, and the controller (MCU or SOC) can determine the light emitting abnormality according to the judgment threshold. Alternatively, the light emitting control circuit 43 can also only store the detected detection signal, and the controller (MCU or SOC) can determine the light emitting abnormality according to the judgment threshold after reading the detection signal monitored by the light emitting control circuit 43 through the interface between the light emitting control circuit 43 and the controller. Of course, the light emitting control circuit 43 can also directly determine the light emitting abnormality according to the detection signal and the judgment threshold, and then send the judgment result to the controller. Finally, the controller 45 reconfigures the control instruction according to the judgment result, or issues an alarm prompt, and records the related information of the judgment result. For example, the related information of the judgment result can include the time, period, and number of times of the abnormal light emission. When the light emitting control circuit 43 directly determines the light emitting abnormality according to the detection signal and the judgment threshold, in another example, the light emitting device driving circuit further includes a threshold register and a controller, the detection circuit 44 is connected to the threshold register, the threshold register is connected to the controller 45, and the judgment threshold is stored in the threshold register; the detection circuit 44 is specifically configured to determine that at least one light emitting device is abnormally emitting light according to the detection signal and the judgment threshold configured by the controller 45 in the threshold register. The threshold register can be Figure 8One of the other registers. The control signal register, the threshold register described above can be integrated in the same chip with the current driving circuit, the detection circuit, etc. can be arbitrarily combined, or separately arranged in different chips on the PCB, for example, can be integrated in the AFE.

[0074] Specifically, referring to Figure 9 The detection circuit 44 can be implemented with an accumulator with enable and reset functions and a comparator, as shown in the figure, where the input of the accumulator is the current control signal Idac of the light emitting device, and the output is the accumulated value Qn. At the beginning of each detection period (for example, it can be a PRF period), the PRF signal resets the accumulator, and the output Qn is 0. When the light emitting device is driven to light up, the switch control signal outputs a pulse, the switch control signal en = 1, enabling the accumulator to start working, and the accumulator counts the current control signal Idac of the light emitting device at the rising edge of each clock cycle CLK. The counting result is output from Qn, and when the comparator determines that the counting result Qn is greater than the judgment threshold, the comparator outputs an alarm or indication signal from the output terminal M_out, indicating that the energy of the light emitting device during this PRF period has exceeded the set judgment threshold. Prompt the system to process or record. Usually, when measuring blood oxygen, 1 PRF period includes two light emitting periods of Dir and one light emitting period of Dr; when measuring heart rate, 1 PRF period includes one light emitting period of Dg and one light emitting period of Dir; when performing electronic device wearing detection, 1 PRF period includes one light emitting period of Dir. Of course, the above mainly illustrates three application scenarios of electronic devices, in other application scenarios, 1 PRF period can also include one or more light emitting periods of a light emitting device, or 1 PRF period can also include one or more light emitting periods of multiple light emitting devices. In the following examples, take 1 PRF period including one light emitting period of Dir, Dg and Dr respectively as an example for detailed description as follows. Combined with Figure 10 The signal timing diagram shown in the figure, based on the above Figure 9The light emitting device driving circuit can be seen that in the detected PRF period, the pulse starting from the PRF period resets the accumulator Qn output to 0, in the first light emitting period T-PW1 of the light emitting device Dg, the switch control signal en=1 couples the common terminal ct with the free terminal c1, the light emitting control signal Idac outputs the light emitting control signal Idac=10 to the current source, the light emitting device Dg lights up, in T-PW1, the first rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=10; in T-PW1, the second rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=20. In the first light emitting period T-PW2 of the light emitting device Dr, the switch control signal en=1 couples the common terminal ct with the free terminal c2, the light emitting control signal Idac outputs the light emitting control signal Idac=15 to the current source, the light emitting device Dr lights up, in T-PW2, the first rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=35; in T-PW2, the second rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=50; in T-PW2, the third rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=65; in the first light emitting period T-PW3 of the light emitting device Dir, the switch control signal en=1 couples the common terminal ct with the free terminal c3, the light emitting control signal Idac outputs the light emitting control signal Idac=60 to the current source, the light emitting device Dir lights up, in T-PW3, the first rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=125; in T-PW3, the second rising edge of CLK, the accumulator counts the current control signal Idac again, Qn=185; then when Pth is set to 180, then in T-PW3, the second rising edge of CLK, since 125<180, the M-out output of the comparator is logic 0, indicating that the light emitting is normal; after the second rising edge of CLK in T-PW3, since 185>180, the M-out output of the comparator is logic 1, indicating that the light emitting is abnormal; of course, in some examples, Pth can also be set to 200, since 185<200, the M-out output is logic 0 throughout the PRF period, indicating that the light emitting is normal. Of course, the above Figure 9 and Figure 10 The provided scheme is mainly exemplified for scenario three of the above embodiment, of course, the accumulator can also be reset by the rising edge of en, so as to realize the accumulation of the current control signal Idac of each light emitting device respectively, thereby realizing the detection of each light emitting device, which will not be described herein.

[0075] In the above-described embodiments, the description of each embodiment has a focus on some aspects, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0076] Although the present application has been described in connection with certain specific features and embodiments thereof, it is to be understood that it is not to be limited to the features and embodiments specifically described, but rather can be practiced with modification and alteration within the scope of the claims and the scope of the application. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. It is to be understood that the application is not to be limited to the particular examples disclosed, but is intended to cover all code falling within the scope of the application as broadly described.

Claims

1. A light emitting device driving circuit, characterized by comprising: The light-emitting device driving circuit comprises: a voltage conversion circuit, a light-emitting assembly, a current driving circuit, a light-emitting control circuit and a detection circuit; any of the light-emitting devices in the light-emitting assembly and the current driving circuit are connected in series between an output terminal and a ground terminal of the voltage conversion circuit; the light-emitting control circuit is configured to output a light-emitting control signal to the current driving circuit; the current driving circuit is configured to provide a current to at least one light-emitting device according to the light-emitting control signal; the detection circuit is configured to detect the light-emitting control signal and generate a detection signal, wherein the detection circuit or a controller connected with the detection circuit determines that the light-emitting assembly is abnormal according to the detection signal; the current driving circuit comprises a current source and a switching switch circuit; a common terminal of the switching switch circuit is coupled with the current source, and any of the light-emitting devices is coupled with any selection terminal of the switching switch circuit; the light-emitting control signal comprises a switch control signal and a current control signal; the switching switch circuit is configured to turn on the selection terminal coupled with a target light-emitting device of the at least one light-emitting device to couple the current source with the target light-emitting device in at least one light-emitting period of the target light-emitting device according to the switch control signal; the target light-emitting device is any of the at least one light-emitting device; the current source is configured to provide a current to the target light-emitting device according to the current control signal; the detection circuit is configured to generate the detection signal according to an accumulated value of the current control signal corresponding to the at least one light-emitting device in a first time period, wherein when the accumulated value exceeds a judgment threshold, it is determined that the light-emitting assembly is abnormal, and the target light-emitting device continuously emits light in one light-emitting period.

2. The light emitting device driving circuit according to claim 1, wherein the at least one light-emitting device comprises a first light-emitting device; the switching switch circuit is specifically configured to turn on the selection terminal coupled with the first light-emitting device to couple the current source with the first light-emitting device in at least one light-emitting period according to the switch control signal; the current source is specifically configured to provide a current to the first light-emitting device according to the current control signal; the detection circuit is specifically configured to generate the detection signal according to an accumulated value of the current control signal corresponding to the first light-emitting device in a first time period, wherein when the accumulated value exceeds a judgment threshold, it is determined that the light-emitting assembly is abnormal, and the first light-emitting device continuously emits light in one light-emitting period.

3. The light-emitting device driving circuit according to claim 2, wherein the first time period comprises at least one detection period, and each detection period comprises at least one light-emitting period.

4. The light emitting device driving circuit according to claim 1, wherein the at least one light-emitting device comprises a first light-emitting device and a second light-emitting device; The switch circuit is specifically configured to couple the common terminal to a selection terminal coupled to the first light emitting device in at least one light emitting period of the first light emitting device according to the switch control signal, so as to couple the current source to the first light emitting device; or couple the common terminal to a selection terminal coupled to the second light emitting device in at least one light emitting period of the second light emitting device according to the switch control signal, so as to couple the current source to the second light emitting device. The current source is specifically configured to provide a current to the first light emitting device according to the current control signal when the current source is coupled to the first light emitting device, and provide a current to the second light emitting device according to the current control signal when the current source is coupled to the second light emitting device. The detection circuit is specifically configured to generate the detection signal according to an accumulated value of the current control signal corresponding to the first light emitting device and the second light emitting device in a first time period, wherein the accumulated value exceeds a judgment threshold value, and the first time period includes at least one detection period, and one detection period includes at least one light emitting period of the first light emitting device and at least one light emitting period of the second light emitting device, and the first light emitting device continuously emits light in one light emitting period of the first light emitting device, and the second light emitting device continuously emits light in one light emitting period of the second light emitting device.

5. A light emitting device driving circuit according to any one of claims 2 to 4, characterized in that, The controller is configured to generate the judgment threshold value according to a maximum accumulated value detected in a second time period.

6. The light emitting device driving circuit according to any one of claims 2 to 4, wherein The controller is configured to generate the judgment threshold value by increasing or decreasing a predetermined offset according to a maximum accumulated value detected in a second time period.

7. A light emitting device driving circuit according to any one of claims 2 to 4, wherein The controller is configured to obtain an electrical parameter of the light emitting device by looking up a table, calculate the judgment threshold value according to the electrical parameter of the light emitting device, the table including a corresponding relationship between the electrical parameter of the light emitting device and the light emitting device, and the electrical parameter including a maximum current control signal of the light emitting device in one light emitting period.

8. The light emitting device driving circuit according to any one of claims 2 to 4, wherein The controller is configured to obtain the judgment threshold value by looking up a table, the table including a corresponding relationship between the electrical parameter of the light emitting device and the judgment threshold value, and the electrical parameter including a current transfer ratio of the light emitting device and a photodetector.

9. The light emitting device driving circuit according to any one of claims 2 to 4, wherein The controller is configured to calculate the judgment threshold value by a predetermined formula, The predetermined formula is represented as Pth=k×CTR+B, CTR is a current transfer ratio of the light emitting device and a photodetector, k and B are constants, and Pth is the judgment threshold value.

10. The light emitting device driving circuit according to any one of claims 2 to 4, wherein The controller is configured to determine the judgment threshold value according to a working scenario, and the working scenario includes at least one of the following: standby scenario, sleep scenario, and motion scenario.

11. The light emitting device driving circuit according to claim 1, wherein The light emitting device driving circuit further includes at least one control signal register and the controller, the light emitting control circuit is connected to the at least one control signal register, and the control signal register is connected to the controller. The light emitting control circuit is specifically configured to generate the light emitting control signal according to a control instruction configured by the controller in the at least one control signal register; The controller is configured to reconfigure the control instruction when it is determined that the light emitting component emits light abnormally.

12. The light emitting device driving circuit according to claim 1, wherein The light emitting device driving circuit further comprises a threshold register and the controller, the detection circuit is connected to the threshold register, the threshold register is connected to the controller, and the determination threshold is stored in the threshold register. The detection circuit is specifically configured to determine that the light emitting component emits light abnormally according to the detection signal and a determination threshold configured by the controller in the threshold register.

13. The light emitting device driving circuit according to claim 1, wherein The light emitting device driving circuit comprises an analog front end (AFE), and the AFE comprises a current driving circuit, a light emitting control circuit, and a detection circuit.

14. The light emitting device driving circuit according to claim 1, wherein The voltage conversion circuit at least comprises any one of a boost circuit and a buck-boost circuit.

15. A PPG sensor, characterized in that, The light emitting device driving circuit according to any one of claims 1-14; wherein the detector is configured to detect a test light signal of the light emitting device reflected and / or scattered by a detected object.

16. An electronic device, comprising: The light emitting device driving circuit according to any one of claims 1-14, or the PPG sensor according to claim 15.

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