Detection device

Abstract

The present invention provides a detection device that can obtain appropriate detection results and suppresses power consumption. A detection device according to the present invention includes a light source that can shine light of a plurality of colors that have different wavelengths at a finger on which the detection device is installed, a light sensor that receives light from the finger as input and outputs a signal that corresponds to the light, and a detection circuit that performs signal processing on the basis of the output signal of the light sensor. The light sensor includes a first light sensor and a second light sensor that is provided further from the light source. The light source includes a first light source that can emit visible light, a second light source that can emit near infrared light or infrared light, and a third light source that can emit visible light that is different from the visible light of the first light source. The first light sensor is connected to the detection circuit during a first light emission period in which the third light source emits light but the first and second light sources do not, and at least one of the first light sensor and the second light sensor is connected to the detection circuit during a second light emission period in which the first or second light source emits light but the third light source does not.

Description

Detection device

[0001] The present invention relates to a detection device.

[0002] Optical sensors capable of detecting fingerprint patterns and blood vessel patterns are known (see, for example, Patent Document 1). In the optical sensor described in Patent Document 1, multiple pixels may be driven collectively by simultaneously selecting multiple signal lines.

[0003] International Publication No. 2020 / 213621

[0004] However, when a detection device is worn on the human body, if the distance from the detection unit to the human body is long, appropriate detection results may not be obtained. Also, detection devices worn on the human body may have small battery capacities, so it is necessary to reduce power consumption.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a detection device that can obtain appropriate detection results and reduce power consumption.

[0006] In order to solve the above-mentioned problems and achieve the object, a detection device according to an aspect of the present disclosure includes a light source capable of irradiating a single finger on which the detection device is worn with light of a plurality of colors having different wavelengths, an optical sensor that receives light from the finger and outputs a signal corresponding to the light, and a detection circuit that performs signal processing based on the signal output by the optical sensor, wherein the optical sensor includes a first optical sensor and a second optical sensor that is disposed at a position farther from the light source than the first optical sensor, and the light source, the first optical sensor, and the second optical sensor are configured to be in a state where the light source, the first optical sensor, and the second optical sensor are ... the first optical sensor and the second optical sensor are arranged in that order, and the light sources include a first light source capable of emitting visible light, a second light source capable of emitting near-infrared light or infrared light, and a third light source capable of emitting visible light different from the visible light of the first light source, and during a first light emission period when the first light source and the second light source are not emitting light and the third light source is emitting light, the first optical sensor is connected to the detection circuit, and during a second light emission period when the third light source is not emitting light and the first light source or the second light source is emitting light, at least one of the first optical sensor and the second optical sensor is connected to the detection circuit.

[0007] According to the present invention, it is possible to realize a detection device that can obtain appropriate detection results and reduce power consumption.

[0008] FIG. 1 is an external view showing a detection device according to an embodiment. FIG. 2 is a diagram illustrating the distance between a light source and an optical sensor. FIG. 3 is a diagram illustrating a case where green light is irradiated onto a finger. FIG. 4 is a diagram illustrating a case where near-infrared light or red light is irradiated onto a finger. FIG. 5 is a diagram illustrating whether reflected light of green light, near-infrared light, and red light reaches the optical sensor area. FIG. 6 is a block diagram illustrating an example of the internal configuration of the detection device. FIG. 7 is a diagram illustrating functions realized by each unit within the detection device. FIG. 8 is a diagram illustrating an example of the circuit configuration of the optical sensor area. FIG. 9 is a waveform diagram illustrating an example of operation when measuring a pulse wave using the detection device. FIG. 10 is a flowchart illustrating an example of a process for measuring a pulse wave using the detection device. FIG. 11 is a waveform diagram illustrating an example of operation when measuring SpO2 using the detection device. FIG. 12 is a flowchart illustrating an example of a process for measuring SpO2 using the detection device. FIG. 13 is a diagram illustrating example SpO2 values. FIG. 14 is a flowchart illustrating a method for measuring blood oxygen levels using the detection device.

[0009] Modes for carrying out the invention (embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the components described below can be combined as appropriate. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, for clarity of explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each figure, elements similar to those described above with reference to the previous figures may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0010] FIG. 1 is an external view showing a detection device according to an embodiment. In FIG. 1, the detection device 100 has a shape of a finger ring. The detection device 100 has a hollow portion 200. A finger can be inserted into the hollow portion 200 of the detection device 100. In other words, the detection device 100 has a ring-shaped housing. A user of the detection device 100 can wear the detection device 100 on one finger.

[0011] 1 , a light source 5 and an optical sensor 6 are provided on an inner surface 101 of the detection device 100. That is, the light source 5 and the optical sensor 6 are housed in a ring-shaped housing of the detection device 100. The light source 5 can irradiate light toward a hollow portion 200. When a finger is inserted into the hollow portion 200, light can be irradiated from the light source 5 toward the finger.

[0012] The light source 5 is a light source capable of emitting light of multiple colors having different wavelengths. The light source 5 includes a light source 51 capable of emitting red light, a light source 52 capable of emitting near-infrared light, and a light source 53 capable of emitting green light. The light source 51 is, for example, a red LED (Light Emitting Diode). The light source 52 is, for example, a near-infrared LED. The light source 53 is, for example, a green LED. Red light and green light are visible light. Near-infrared light is not visible light. An infrared light source may be used instead of the light source 52, which is a near-infrared light source. In other words, at least one of a near-infrared light source and an infrared light source is used. The light source 51 corresponds to the "first light source" in this disclosure. The light source 52 corresponds to the "second light source" in this disclosure. The light source 53 corresponds to the "third light source" in this disclosure.

[0013] The optical sensor 6 is, for example, an organic photodiode (OPD), and outputs an electrical signal in response to irradiated light. The optical sensor 6 has an optical sensor region 61 and an optical sensor region 62. Focusing on the light source 5, the optical sensor region 61, and the optical sensor region 62, the light source 5, the optical sensor region 61, and the optical sensor region 62 are arranged on the inner surface 101 in this order. The optical sensor region 61 corresponds to a "first optical sensor" in the present disclosure. The optical sensor region 62 corresponds to a "second optical sensor" in the present disclosure.

[0014] 2 is a diagram illustrating the distance between the light source 5 and the optical sensor 6. In Fig. 5, the X direction is the rotation direction along the inner circumferential surface of the ring shape, and the Y direction is the direction perpendicular to the X direction.

[0015] 2, the optical sensor region 61 and the optical sensor region 62 are different in distance from the light source 5. The optical sensor region 61 is disposed closer to the light source 5 than the optical sensor region 62. The optical sensor region 62 is disposed farther from the light source 5 than the optical sensor region 61. The distance in the X direction from the center position of the light source 5 to the center position of the optical sensor region 61 is defined as distance d1. The distance in the X direction from the center position of the light source 5 to the center position of the optical sensor region 62 is defined as distance d2. Distance d1 is shorter than distance d2. Distance d2 is longer than distance d1.

[0016] 3 and 4 are cross-sectional views showing a state in which the detection device 100 is worn on the finger of a user of the detection device 100. FIG.

[0017] 3 is a diagram showing a case where green light is irradiated onto a finger. Green light is irradiated onto a finger F from a green light source 53 provided on the inner surface of the detection device 100. The green light is reflected by the surface layer close to the surface of the finger F. Therefore, reflected light LG from the finger F, which corresponds to the green light, reaches an area of ​​the optical sensor 6 close to the light source 53, i.e., the optical sensor area 61 which is close to the light source 53. Therefore, the reflected green light LG is detected by the optical sensor area 61.

[0018] However, the reflected green light LG does not reach an area far from the light source 53, i.e., an area that is far away from the light source 53. Therefore, the reflected green light LG is not detected by the optical sensor area 62.

[0019] 4 is a diagram showing a case where near-infrared light or red light is irradiated onto a finger F. Near-infrared light is irradiated onto a finger F from a near-infrared light source 52 provided on the inner surface of the detection device 100. The near-infrared light is reflected at a position deeper than the surface of the finger F. Therefore, reflected light LI from the finger F, which corresponds to the near-infrared light, reaches a region of the optical sensor 6 close to the light source 52, i.e., the optical sensor region 61 which is close to the light source 52. Therefore, the reflected light LI of the near-infrared light is detected by the optical sensor region 61.

[0020] Furthermore, the reflected near-infrared light LI also reaches an area of ​​the optical sensor 6 far from the light source 52, i.e., an optical sensor area 62 that is far from the light source 52. Therefore, the reflected near-infrared light LI is also detected by the optical sensor area 62.

[0021] The red light source 51 is similar to the case of Fig. 4. That is, the red light reflected from the finger F is reflected at a position deeper than the surface of the finger F, and therefore reaches the optical sensor areas 61 and 62 and is detected by them.

[0022] 5 is a diagram illustrating whether the reflected light of green light, near-infrared light, and red light reaches the optical sensor area. As described with reference to FIGS. 3 and 4, the penetration depth of light into a living body varies depending on the emitted color.

[0023] Green light (GREEN) is reflected by the surface layer close to the surface of the finger F. The reflected green light reaches the optical sensor region 61. Therefore, the pulse wave can be obtained by using the detection signal from the optical sensor region 61. On the other hand, the reflected green light does not reach the optical sensor region 62. Therefore, the pulse wave cannot be obtained even if the detection signal from the optical sensor region 62 is used.

[0024] Near-infrared light (IR) and red light (RED) are reflected at a position deeper than the surface of the finger F. The reflected near-infrared light and red light reach both the optical sensor region 61 and the optical sensor region 62. Therefore, the pulse wave can be acquired by using the detection signal from at least one of the optical sensor region 61 and the optical sensor region 62.

[0025] Fig. 6 is a block diagram showing an example of the internal configuration of the detection device 100. As shown in Fig. 6, the detection device 100 includes an acceleration sensor 3, a light source 5, an LED driver 50, a light sensor 6, a short-range wireless communication driver 7, a battery 8, a coil 9, a battery driver 81, and a control circuit 10.

[0026] The acceleration sensor 3 detects acceleration applied to the detection device 100. As will be described later, the detected value of the acceleration applied to the detection device 100 is used to determine the state of the person wearing the detection device 100. The acceleration sensor 3 is, for example, a three-axis acceleration sensor.

[0027] The light source 5 includes light sources 51, 52, and 53. In this example, the light source 51 is a red LED, the light source 52 is a near-infrared LED, and the light source 53 is a green LED. In the following description, the light source 51 will be referred to as the "red LED 51," the light source 52 as the "near-infrared LED 52," and the light source 53 as the "green LED 53." The LED driver 50 drives the red LED 51, the near-infrared LED 52, and the green LED 53 to light them up.

[0028] The optical sensor 6 includes optical sensor regions 61 and 62. The optical sensor regions 61 and 62 convert input light into an electrical signal. The optical sensor regions 61 and 62 operate independently of each other.

[0029] The short-range wireless communication driver 7 has an antenna (not shown). The short-range wireless communication driver 7 transmits and receives signals between the detection device 100 and other devices. The short-range wireless communication driver 7 can transmit data measured by each part of the detection device 100 to other devices. The short-range wireless communication driver 7 can also receive data transmitted by other devices.

[0030] The battery 8 supplies power to each component of the detection device 100. The battery 8 is, for example, a lithium ion battery. The battery driver 81 controls the battery 8. The battery 8 is charged by the battery driver 81.

[0031] The coil 9 is a charging coil for charging the battery 8. The coil 9 has a winding wound along the housing of the detection device 100. An induced current flows in the coil 9 based on the applied magnetic field. The induced current flowing in the coil 9 can charge the battery 8.

[0032] The control circuit 10 controls each part of the detection device 100. The control circuit 10 is, for example, an integrated circuit (IC) such as a microcontroller. The control circuit 10 may also be, for example, a programmable logic device (PLD) such as a field programmable gate array (FPGA).

[0033] The control circuit 10 includes a motion detection circuit 11, a sleep detection circuit 12, an AFE (Analog Front End) 13, a pulse wave measurement circuit 14, a memory 15, a communication circuit 16, a power supply circuit 17, and a CPU (Central Processing Unit) 18. These are connected by a bus, and can exchange data with each other via the bus.

[0034] The motion detection circuit 11 detects the motion state and the stationary state of the user of the detection device 100 based on the output of the acceleration sensor 3. The sleep detection circuit 12 detects the sleep state and the wakefulness state of the user of the detection device 100 based on the output of the acceleration sensor 3 and the measurement results by the pulse wave measurement circuit 14.

[0035] Pulse wave measurement circuit 14 is connected to LED driver 50, AFE 13, and optical sensor 6. Pulse wave measurement circuit 14 measures the pulse frequency, blood oxygen concentration, etc. based on the detection data of optical sensor 6. Pulse wave measurement circuit 14 measures the change in the detection value of optical sensor 6 over time as a pulse wave.

[0036] The memory 15 is a storage unit that stores various types of data. The memory 15 may include, for example, a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), etc.

[0037] The communication circuit 16 is connected to the short-range wireless communication driver 7. The communication circuit 16 transmits measurement results and the like to an external device. The external device is, for example, a mobile terminal such as a smartphone or tablet held by a user of the detection device 100. Mobile terminals such as smartphones and tablets have a display screen. By displaying data from the detection device 100 on the screen, the user of the detection device 100 can check the data received from the detection device 100.

[0038] The power supply circuit 17 is connected to a battery driver 81. The power supply circuit 17 controls charging of the battery 8 and supplies power from the battery 8 to each component.

[0039] The CPU 18 is a control unit that controls each unit in the control circuit 10. The CPU 18 executes a predetermined program to measure or calculate biological information such as pulse wave velocity, blood pressure, and pulse frequency.

[0040] (Functions of Each Unit of the Detection Device) Fig. 7 is a diagram showing the functions realized by each unit in the detection device 100. As shown in Fig. 7, the motion detection circuit 11 realizes determination units 111 to 114. The determination units 111 and 112 input the acceleration acquired by the acceleration sensor 3.

[0041] The determination unit 111 determines whether the acceleration acquired by the acceleration sensor 3 is equal to or greater than a predetermined threshold value A. When the determination unit 111 determines that the acceleration is equal to or greater than the predetermined threshold value A, the determination unit 113 determines that the user of the detection device 100 is in an exercising state.

[0042] The determination unit 112 determines that the acceleration acquired by the acceleration sensor 3 is less than a predetermined threshold value A. When the determination unit 112 determines that the acceleration is less than the predetermined threshold value A, the determination unit 114 determines that the user of the detection device 100 is in a stationary state.

[0043] Furthermore, the sleep detection circuit 12 realizes the determination units 121 to 128. The determination units 121 and 123 receive an input of the acceleration acquired by the acceleration sensor 3. The determination units 122 and 124 receive an input of the pulse rate based on the pulse wave measured by the pulse wave measurement circuit 14.

[0044] The determination unit 121 determines whether the acceleration acquired by the acceleration sensor 3 is less than a predetermined threshold value B. The determination unit 122 determines whether the pulse rate input from the pulse wave measurement circuit 14 is less than a predetermined threshold value C. The determination unit 125 performs a logical product (AND) determination on the determination results of the determination unit 121 and the determination results of the determination unit 122.

[0045] The determination unit 127 determines the sleeping state of the user of the detection device 100 based on the result of the determination by the determination unit 125. When the result of the determination by the determination unit 125 is that the acceleration acquired by the acceleration sensor 3 is less than the threshold value B and the pulse rate input from the pulse wave measurement circuit 14 is less than the threshold value C, the determination unit 127 determines that the user of the detection device 100 is sleeping.

[0046] The determination unit 123 determines whether the acceleration acquired by the acceleration sensor 3 is equal to or greater than a predetermined threshold value B. The determination unit 124 determines whether the pulse rate input from the pulse wave measurement circuit 14 is equal to or greater than a predetermined threshold value C. The determination unit 126 performs a logical sum (OR) determination on the determination results of the determination unit 123 and the determination results of the determination unit 124.

[0047] The determination unit 128 determines the wakefulness state of the user of the detection device 100 based on the result of the determination by the determination unit 126. If the result of the determination by the determination unit 126 is that the acceleration acquired by the acceleration sensor 3 is equal to or greater than threshold value B, or if the pulse rate input from the pulse wave measurement circuit 14 is equal to or greater than threshold value C, the determination unit 128 determines that the user of the detection device 100 is in an wakefulness state.

[0048] Furthermore, the CPU 18 realizes determination units 181 to 185 and a data calculation unit 186. The determination unit 181 determines whether or not to start continuous measurement of the pulse wave based on the detection result of the motion detection circuit 11. The determination unit 181 determines to start continuous measurement of the pulse wave when the motion detection circuit 11 determines that the user of the detection device 100 is in an exercising state. In other words, when the acceleration acquired by the velocity sensor 3 is equal to or greater than the threshold value A, the determination unit 181 performs signal processing of the pulse wave.

[0049] The determination unit 182 determines whether or not to end the continuous measurement of the pulse wave based on the detection result of the motion detection circuit 11. The determination unit 182 determines to end the continuous measurement of the pulse wave when the motion detection circuit 11 determines that the user of the detection device 100 is stationary. When the determination unit 182 determines to end the continuous measurement of the pulse wave, the determination unit 183 determines to measure the pulse wave at predetermined time intervals. For example, the determination unit 183 determines to measure the pulse wave at five-minute intervals.

[0050] The determination unit 184 determines whether to start measuring the blood oxygen saturation SpO2 based on the detection result of the sleep detection circuit 12. The determination unit 184 determines to start measuring the blood oxygen saturation SpO2 when the sleep detection circuit 12 determines that the user of the detection device 100 is asleep. In other words, when the acceleration acquired by the acceleration sensor 3 is less than threshold B and the pulse rate input from the pulse wave measurement circuit 14 is less than threshold C, measurement of the blood oxygen saturation SpO2 is started.

[0051] The determination unit 185 determines whether or not to end the measurement of the blood oxygen saturation level SpO2 based on the detection result of the sleep detection circuit 12. The determination unit 185 determines to end the measurement of the blood oxygen saturation level SpO2 when the sleep detection circuit 12 determines that the user of the detection device 100 is in an awake state.

[0052] The data calculation unit 186 receives as input the acceleration acquired by the acceleration sensor 3 and the pulse rate from the pulse wave measurement circuit 14. The data calculation unit 186 calculates various types of data. The data resulting from the calculations by the data calculation unit 186 is stored in the memory 15. The memory 15 stores, for example, data on the measured pulse rate and data on the measured blood oxygen saturation.

[0053] (Photosensor Region) Fig. 8 is a diagram showing an example of the circuit configuration of the photosensor region. As shown in Fig. 8, photosensor region 61 includes a photodiode PD1 and a capacitance element C1. Photosensor region 62 includes a photodiode PD2 and a capacitance element C2. Furthermore, output signals from photosensor region 61 and photosensor region 62 are input to a selection circuit SEL. Selection circuit SEL includes switching elements Tr1 and Tr2.

[0054] Photodiode PD1 outputs a current corresponding to the incident light, and charge is accumulated in capacitance element C1 based on this current. Photodiode PD2 outputs a current corresponding to the incident light, and charge is accumulated in capacitance element C2 based on this current.

[0055] A switching element Tr1 of the selection circuit SEL is provided corresponding to the photodiode PD1. A gate signal Gate1 is applied to the gate terminal of the switching element Tr1. When the gate signal Gate1 is at a low level, the switching element Tr1 is turned off, and charge is accumulated in the capacitance element C1 as described above. When the gate signal Gate1 is at a high level, the switching element Tr1 is turned on, and a current based on the charge accumulated in the capacitance element C1 is output.

[0056] A switching element Tr2 of the selection circuit SEL is provided corresponding to the photodiode PD2. A gate signal Gate2 is applied to the gate terminal of the switching element Tr2. When the gate signal Gate2 is at a low level, the switching element Tr2 is turned off, and charge is accumulated in the capacitance element C2 as described above. When the gate signal Gate1 is at a high level, the switching element Tr1 is turned on, and a current based on the charge accumulated in the capacitance element C2 is output.

[0057] That is, based on the levels of the gate signals Gate1 and Gate2, the selection circuit SEL selects and outputs the output signals of the optical sensor region 61 and the optical sensor region 62. The signal passing through the switching element Tr1 from the optical sensor region 61 and the signal passing through the switching element Tr2 from the optical sensor region 62 are combined at a connection point N and input to the AFE 13 as a light-receiving signal Rx1.

[0058] The switching elements Tr1 and Tr2 are configured by thin film transistors, and in this example, are configured by n-channel MOS (Metal Oxide Semiconductor) type TFTs (Thin Film Transistors).

[0059] The AFE 13 is a detection circuit that performs signal processing based on the signal output by the optical sensor 6. The AFE 13 includes a switching element Tr0 and an A / D conversion circuit 130. A reset signal RST is applied to the gate terminal of the transistor that is the switching element Tr0. When the reset signal RST is at a low level, the switching element Tr0 is turned off, and the light reception signal Rx1 is input to the A / D conversion circuit 130. The A / D conversion circuit 130 outputs data corresponding to the light reception signal Rx1. The data output by the A / D conversion circuit 130 is input to the pulse wave measurement circuit 14.

[0060] When the reset signal RST is at a high level, the switching element Tr0 is turned on, and the light reception signal Rx1 is not input to the A / D conversion circuit 130.

[0061] 9 and 10 are diagrams illustrating the operation of measuring a pulse wave during exercise using the detection device 100. In this example, the green LED 53 is turned on to measure the pulse wave.

[0062] 9 is a waveform diagram illustrating an example of operation when measuring a pulse wave using the detection device 100. FIG. 9 shows the lighting state of the LEDs, gate signals Gate1 and Gate2, the light reception signal Rx1, and the reset signal RST.

[0063] As shown in FIG. 9, when measuring a pulse wave using the detection device 100, a sensor reset for resetting the optical sensor area and a sensor readout for reading out data from the optical sensor area are performed alternately.

[0064] During the sensor reset period t11, the green LED 53 is not lit. During the period t11, the gate signal Gate1 is at a high level and the gate signal Gate2 is at a low level. Therefore, the switching element Tr1 is in an on state and the switching element Tr2 is in an off state. Because the reset signal RST is at a high level, the switching element Tr0 is in an on state. The light receiving signal Rx1 is at the ground level, i.e., 0 (V). Therefore, the charges stored in the photodiode PD1 and the capacitance element C1 are discharged. The input to the A / D conversion circuit 130 is 0 (V). Note that the period during which the gate signal Gate1 is at a high level may be a part of the sensor reset period t11, as long as it is long enough to sufficiently discharge the charges stored in the photodiode PD1 and the capacitance element C1.

[0065] During the sensor readout period t12, the green LED 53 is turned on. While the green LED 53 is emitting light, the red LED 51 and near-infrared LED 52 are not emitting light. Period t12 is a first light-emission period during which the red LED 51 and near-infrared LED 52 are not emitting light and the green LED 53 is emitting light. During period t12, the gate signal Gate1 is at a high level and the gate signal Gate2 is at a low level. This causes the switching element Tr1 to be in an on state and the switching element Tr2 to be in an off state. Therefore, a light-receiving signal Rx1 obtained by the optical sensor region 61 is output. Here, when the green LED 53 is emitting light, the switching element Tr1 of the selection circuit SEL sends the output signal of the optical sensor region 61 to the pulse wave measurement circuit 14 via the AFE 13. The pulse wave measurement circuit 14 performs measurement based on the signal output by the optical sensor region 61. In other words, during period t12, the selection circuit SEL connects the optical sensor region 61 to the AFE 13.

[0066] During the sensor readout period t12, the reset signal RST is at a low level, and the switching element Tr0 is in an off state. As a result, the light reception signal Rx1 is input to the A / D conversion circuit 130. Data (not shown) corresponding to the voltage value of the light reception signal Rx1 is output from the A / D conversion circuit 130.

[0067] During period t12, the gate signal Gate2 is at a low level, and the optical sensor region 62 is not used. As described above, the green light from the green LED 53 does not reach the optical sensor region 62, which is located far from the green LED 53, and therefore the optical sensor region 62 is not used. During period t12, the green light from the green LED 53 is received only by the optical sensor region 61, which receives the green light. In other words, the light is received only by the optical sensor region 61, which is close to the green LED 53. During period t12, the optical sensor region 62 is not used, thereby reducing power consumption.

[0068] During the subsequent sensor reset period t13, the green LED 53 is not turned on, and the operation is the same as that during the period t11. Since the reset signal RST is at a high level and the switching element Tr0 is in an on state, the input to the A / D conversion circuit 130 is 0 (V).

[0069] Fig. 10 is a flowchart showing an example of a process for measuring a pulse wave by the detection device 100. Fig. 10 mainly shows the content of the process performed by the motion detection circuit 11 and the CPU 18 (see Fig. 6). The CPU 18 performs a pulse wave measurement process S1.

[0070] 10, first, the motion detection circuit 11 determines whether the user of the detection device 100 is in an exercising state (step S101). If it is determined in step S101 that the user is not in an exercising state (No in step S101), the process waits until it is determined that the user is in an exercising state.

[0071] If it is determined in step S101 that the subject is in a motion state (Yes in step S101), the green LED 53 is turned on (step S102). With the green LED 53 turned on, the optical sensor area 61 is read out (step S103).

[0072] After reading out the optical sensor area 61, the green LED 53 is turned off (step S104). After that, after a predetermined waiting time (WAIT) (step S105), it is determined whether the user of the detection device 100 is stationary (step S106).

[0073] If it is determined in step S106 that the subject is in a stationary state (Yes in step S106), the process ends. On the other hand, if it is determined in step S106 that the subject is not in a stationary state (No in step S106), the process returns to step S102, and the pulse wave measurement process S1 continues.

[0074] 11 and 12 are diagrams illustrating the operation of measuring SpO2 using the detection device 100. In this example, the red LED 51 and the near-infrared LED 52 are alternately illuminated to measure SpO2.

[0075] Fig. 11 is a waveform diagram illustrating an example of operation when SpO2 is measured by the detection device 100. Fig. 11 shows the lighting state of the LED, gate signals Gate1 and Gate2, the light receiving signal Rx1, and the reset signal RST.

[0076] As shown in FIG. 11, when SpO2 is measured by the detection device 100, a sensor reset for resetting the optical sensor area and a sensor readout for reading out data from the optical sensor area are performed alternately.

[0077] During the sensor reset period t21, the red LED 51 and the near-infrared LED 52 are not lit. During the period t21, the gate signals Gate1 and Gate2 are both at a high level, and the switching elements Tr1 and Tr2 are both turned on. Because the reset signal RST is at a high level, the switching element Tr0 is turned on. The light receiving signal Rx1 is at ground level, i.e., 0 (V). Therefore, the charges stored in the photodiodes PD1 and PD2 and the capacitance elements C1 and C2 are discharged. The input to the A / D conversion circuit 130 is 0 (V). Note that the period during which the gate signal Gate1 is at a high level may be a portion of the sensor reset period t21, as long as it is long enough to sufficiently discharge the charges stored in the photodiodes PD1 and PD2 and the capacitance elements C1 and C2.

[0078] During the sensor readout period t22, the red LED 51 is turned on. While the red LED 51 is emitting light, the near-infrared LED 52 and the green LED 53 are not emitting light. Thereafter, the red LED 51 is turned off, and after the off period t0, the near-infrared LED 52 is turned on. The off period t0 is a preparation period in which measurement with the red LED 51 turned on ends and measurement with the near-infrared LED 52 is started. Therefore, during the off period t0, the reset signal RST is at a high level. After the off period t0 has elapsed, the reset signal RST returns to a low level. While the near-infrared LED 52 is emitting light, the red LED 51 and the green LED 53 are not emitting light. The period t22 is a second light emission period in which the green LED 53 is not emitting light and the red LED 51 or the near-infrared LED 52 is emitting light.

[0079] During period t22, both gate signals Gate1 and Gate2 are at a high level. Therefore, both switching elements Tr1 and Tr2 are in an on state. Therefore, a light-receiving signal Rx1 obtained by the optical sensor regions 61 and 62 is output. During the first half of the sensor readout period t22, the voltage value resulting from the illumination of the red LED 51 is output as the light-receiving signal Rx1. During the second half of the sensor readout period t22, the voltage value resulting from the illumination of the near-infrared LED 52 is output as the light-receiving signal Rx1. When the red LED 51 or the near-infrared LED 52 is emitting light, the switching elements Tr1 and Tr2 of the selection circuit SEL send an output signal from the optical sensor region 61 or 62 that is receiving light to the pulse wave measurement circuit 14 via the AFE 13. During period t22, the pulse wave measurement circuit 14 performs measurement based on the signal output by at least one of the optical sensor regions 61 and 62. That is, in the period t22, the selection circuit SEL connects at least one of the optical sensor region 61 and the optical sensor region 62 to the AFE 13.

[0080] During the sensor readout period t22, the reset signal RST changes from low to high and back to low again. During the off period t0 within period t22, the reset signal RST is high, causing the switching element Tr0 to be in the on state. The light-receiving signal Rx1 is at ground level, i.e., 0 (V). Therefore, the input to the A / D conversion circuit 130 is 0 (V). Data (not shown) corresponding to the voltage value of the light-receiving signal Rx1 is output from the A / D conversion circuit 130. During the first half of the sensor readout period t22, data corresponding to the voltage value resulting from the illumination of the red LED 51 is obtained. During the second half of the sensor readout period t22, data corresponding to the voltage value resulting from the illumination of the near-infrared LED 52 is obtained. In other words, the red LED 51 and the near-infrared LED 52 are alternately illuminated, and SpO2 is measured based on signals obtained by both the optical sensor region 61 and the optical sensor region 62.

[0081] During period t22, unlike period t12 in Fig. 9 , both gate signals Gate1 and Gate2 are at a high level, and both optical sensor region 61 and optical sensor region 62 are used. That is, light is received by both optical sensor region 61 and optical sensor region 62. By expanding the light-receiving area compared to period t12 in Fig. 9 , the sensitivity of light reception can be increased, and more accurate measurement results can be obtained.

[0082] During the subsequent sensor reset period t23, the red LED 51 and the near-infrared LED 52 are not turned on, and the operation is the same as that during the period t21. Since the reset signal RST is at a high level and the switching element Tr0 is in an on state, the input to the A / D conversion circuit 130 is 0 (V).

[0083] In the above example, during period t22, the output signals from both the optical sensor region 61 and the optical sensor region 62 are connected to the AFE 13, but the output signal from either the optical sensor region 61 or the optical sensor region 62 may be connected to the AFE 13. In other words, when the red LED 51 or the near-infrared LED 52 is emitting light, the green LED 53 is not caused to emit light, and the output signal from at least one of the optical sensor region 61 and the optical sensor region 62 is connected to the AFE 13.

[0084] Fig. 12 is a flowchart showing an example of a process for measuring SpO2 by the detection device 100. Fig. 12 mainly shows the content of the process performed by the sleep detection circuit 12 and the CPU 18 (see Fig. 6). The CPU 18 performs an SpO2 measurement process S2.

[0085] 12, first, the sleep detection circuit 12 determines whether the user of the detection device 100 is asleep (step S201). If it is determined in step S201 that the user is not asleep (No in step S201), the process waits until it is determined that the user is asleep.

[0086] If it is determined in step S201 that the subject is in a sleeping state (Yes in step S201), the red LED 51 is turned on (step S202). With the red LED 51 turned on, the optical sensor areas 61 and 62 are read out (step S203). After the optical sensor areas 61 and 62 are read out, the red LED 51 is turned off (step S204).

[0087] Next, the near-infrared LED 52 is turned on (step S205). With the near-infrared LED 52 turned on, the optical sensor areas 61 and 62 are read out (step S206). After the optical sensor areas 61 and 62 are read out, the near-infrared LED 52 is turned off (step S207). After a predetermined waiting time (WAIT) has elapsed (step S208), it is determined whether the user of the detection device 100 is awake (step S209).

[0088] If it is determined in step S209 that the subject is in an awake state (Yes in step S209), the process ends. On the other hand, if it is determined in step S209 that the subject is not in an awake state (No in step S209), the process returns to step S202, and the SpO2 measurement process S2 continues.

[0089] According to the SpO2 measurement process described with reference to FIG. 12, both the optical sensor region 61 and the optical sensor region 62 are used, thereby increasing the sensitivity of received light and making it possible to obtain more accurate measurement results.

[0090] (Method for Measuring Blood Oxygen Level) Blood oxygen level (hereinafter referred to as SpO2), which is biological information, can be obtained by measuring light passing through a living body such as a finger. For example, SpO2 can be measured by the following formula (1): SpO2=b-a·R (1)

[0091] As shown in the above formula (1), SpO2 is a linear function of the value R. In the above formula (1), "a" and "b" are predetermined coefficients. In formula (1), the value R is defined by the following formula (2): R = (ACr / DCr) / (ACir / DCir) (2)

[0092] In the above equation (2), ACr is the AC component of the red light (Red) measurement value, DCR is the DC component of the red light measurement value, ACir is the AC component of the near-infrared light (IR) measurement value, and DCir is the DC component of the near-infrared light measurement value. The AC component is the component of the pulse wave that appears in the DC current. SpO2, which is a linear function of the value R, is calibrated using the oxygen concentration obtained by previously sampling blood.

[0093] More specifically, the SpO2 value can be obtained as follows. That is, the SpO2 value corresponding to the above-mentioned value R is measured in advance, and the SpO2 value is obtained based on the measurement curve. FIG. 13 is a diagram showing an example of SpO2 values. The measurement curve in FIG. 13 is, for example, a calculated value of the above-mentioned value R, with the vertical axis representing the SpO2 value. When the Ir light is greater than the Red light (Ir>Red), the value R is less than 1.0, and when the Red light is greater than the Ir light (Ir<Red), the value R is greater than 1.0.

[0094] As shown in Fig. 13, by calculating the value R, the SpO2 value corresponding to that value R can be obtained. For example, by using curve CC1 in Fig. 13, when the value R is 0.9, the SpO2 value can be obtained as approximately 83%. Also, by using curve CC2 in Fig. 13, when the value R is 0.9, the SpO2 value can be obtained as approximately 87%.

[0095] Furthermore, by determining the coefficients a and b so that the equation approximates the curve CC1 or the curve CC2, the SpO2 value can be obtained using equation (1).

[0096] 14 is a flowchart showing a method for measuring blood oxygen levels using the detection device 100. In FIG. 14, the pulse wave measurement circuit 14 causes the LED driver 50 to turn on the near-infrared LED 52 (step S401). The pulse wave measurement circuit 14 measures the output current of the optical sensor 6 (step S402). The current measurement result in step S402 is stored in the memory 15 (step S403). The pulse wave measurement circuit 14 causes the LED driver 50 to turn off the near-infrared LED 52 (step S404).

[0097] The pulse wave measurement circuit 14 also turns on the red LED 51 using the LED driver 50 (step S405). The pulse wave measurement circuit 14 measures the output current of the optical sensor 6 (step S406). The current measurement result obtained in step S406 is stored in the memory 15 (step S407). The pulse wave measurement circuit 14 turns off the red LED 51 using the LED driver 50 (step S408). The pulse wave measurement circuit 14 returns to step S401 and repeats the above process. That is, the pulse wave measurement circuit 14 alternately turns on the red LED 51 and the near-infrared LED 52, repeatedly measures the optical sensor current using the optical sensor 6, and stores the results in the memory 15. As described above, the corresponding photodiodes are reset before the red LED 51 and the near-infrared LED 52 are turned on.

[0098] The control circuit 10 performs waveform analysis (step S409) on the measurement results of the output current of the optical sensor 6 due to the lighting of the near-infrared LED 52, which are stored in the memory 15. Through this waveform analysis, the average value (DCir) and amplitude (ACir) of the near-infrared signal waveform are calculated (steps S410 and S411).

[0099] Furthermore, the control circuit 10 performs waveform analysis on the measurement results of the output current of the optical sensor 6 due to the lighting of the red LED 51, which are stored in the memory 15 (step S412). Through this waveform analysis, the average value (DCr) and amplitude (ACr) of the red signal waveform are calculated (steps S413 and S414).

[0100] Next, the control circuit 10 calculates the value R for calculating the blood oxygen saturation SpO2 (step S415). The coefficient a for calculating the blood oxygen saturation SpO2 is input in advance (step S416) and stored in the memory 15 (step S417). The coefficient b for calculating the blood oxygen saturation SpO2 is also input in advance (step S418) and stored in the memory 15 (step S419). The control circuit 10 calculates the blood oxygen saturation SpO2 based on the above formula (1) (step S420).

[0101] The SpO2 obtained by the above process is transmitted to another device via the communication circuit 16 and the short-range wireless communication driver 7 (step S421). The SpO2 is transmitted to, for example, a smartphone. In this example, transmission from the detection device 100 to the other device is performed via short-range wireless communication.

[0102] 3 Acceleration sensor 5, 51, 52, 53 Light source 6 Optical sensor 10 Control circuit 11 Movement detection circuit 12 Sleep detection circuit 14 Pulse wave measurement circuit 61, 62 Optical sensor area 100 Detection device 200 Hollow portion F Finger PD1, PD2 Photodiodes SEL Selection circuit Tr0, Tr1, Tr2 Switching elements

Claims

1. A light source capable of emitting multiple colors of light with different wavelengths onto a single finger is attached, A light sensor that takes light from the aforementioned finger as input and outputs a signal corresponding to the aforementioned light, A detection circuit that performs signal processing based on the signal output by the aforementioned optical sensor, Includes, The light sensor includes a first light sensor and a second light sensor positioned at a greater distance from the light source than the first light sensor. The light source, the first light sensor, and the second light sensor are arranged in the order of the light source, the first light sensor, and the second light sensor. The light source includes a first light source capable of emitting visible light, a second light source capable of emitting near-infrared light or infrared light, and a third light source capable of emitting visible light different from the visible light of the first light source. During the first light emission period when the first light source and the second light source are not emitting light and the third light source is emitting light, the first light sensor is connected to the detection circuit. During a second light emission period in which the third light source is not emitting light and the first or second light source is emitting light, at least one of the first and second light sensors is connected to the detection circuit. Detection device.

2. The detection circuit performs signal processing based on the signals output by the first and second light sensors during the second light emission period. The detection device according to claim 1.

3. During the second light emission period, light is received by both the first and second light sensors. The detection device according to claim 1 or claim 2.

4. It also includes a pulse wave measurement circuit, The detection device according to claim 2, wherein the pulse wave measurement circuit measures the change in the detected value over time as a pulse wave with respect to the detected value of the optical sensor.

5. The visible light that the third light source can emit is green light. The detection device according to claim 1 or claim 2.

6. The first light source and the second light source are alternately illuminated, and blood oxygen saturation is measured based on signals obtained from both the first and second light sensors. The detection device according to claim 3.

7. The system further includes an acceleration sensor that acquires acceleration, and performs pulse wave signal processing when the acceleration acquired by the acceleration sensor is greater than or equal to a predetermined threshold. The detection device according to claim 1 or 2.

8. When the acceleration acquired by the acceleration sensor is below a predetermined threshold and the pulse rate is below a predetermined threshold, blood oxygen saturation is measured. The detection device according to claim 7.

9. The system further includes a memory for storing the measured pulse rate data and the measured blood oxygen saturation data. The detection device according to claim 8.

10. The system further includes a selection circuit for selecting the first light sensor and the second light sensor, The aforementioned selection circuit is During the first light emission period, the first light sensor is connected to the detection circuit. During the second light emission period, connect at least one of the first light sensor and the second light sensor to the detection circuit. The detection device according to claim 1 or 2.

11. The first light source, the second light source, the third light source, the first light sensor, and the second light sensor are housed in a ring-shaped housing. The detection device according to claim 1 or 2.