Patent Application
20220031182
What is disclosed herein relates to a detection device.
Optical sensors capable of detecting a fingerprint pattern and/or a vascular pattern are known (for example, Japanese Patent Application Laid-open Publication No. 2009-032005).
It is desired to obtain a pulse wave velocity using such an optical sensor.
For the foregoing reasons, there is a need for a detection device capable of obtaining the pulse wave velocity.
According to an aspect, a detection device includes: a first optical sensor; a second optical sensor disposed at a predetermined distance from the first optical sensor; a light source configured to emit light to be detected by the first optical sensor and the second optical sensor facing a living body tissue including a blood vessel; and a processor configured to calculate a pulse wave velocity of the blood vessel based on a time-series variation of an output of the first optical sensor, a time-series variation of an output of the second optical sensor, and the predetermined distance.
The following describes a mode (an embodiment) for carrying out the present invention in detail with reference to the drawings. The present invention is not limited to the description of the embodiment given below. Components described below include those easily conceivable by those skilled in the art or those substantially identical thereto. Moreover, the components described below can be appropriately combined. The disclosure is merely an example, and the present invention naturally encompasses appropriate modifications easily conceivable by those skilled in the art while maintaining the gist of the invention. To further clarify the description, the drawings schematically illustrate, for example, widths, thicknesses, and shapes of various parts as compared with actual aspects thereof, in some cases. However, they are merely examples, and interpretation of the present invention is not limited thereto. The same element as that illustrated in a drawing that has already been discussed is denoted by the same reference numeral through the description and the drawings, and detailed description thereof will not be repeated in some cases where appropriate.
In this disclosure, when an element is described as being “on” another element, the element can be directly on the other element, or there can be one or more elements between the element and the other element.
A control board 121 is electrically coupled to the sensor base member 21 through a flexible printed circuit board 71. The flexible printed circuit board 71 is provided with the detection circuit 48. The control board 121 is provided with the control circuit 122 and the power supply circuit 123. The control circuit 122 is, for example, a field programmable gate array (FPGA). The control circuit 122 supplies control signals to the sensor 10, the gate line drive circuit 15, and the signal line selection circuit 16 to control a detection operation of the sensor 10. The control circuit 122 supplies control signals to the first light sources 61 and the second light sources 62 to control to turn on and off the first light sources 61 and the second light sources 62. The power supply circuit 123 supplies voltage signals including, for example, a sensor power supply signal VDDSNS (refer to
The sensor base member 21 has a detection area AA and a peripheral area GA. The detection area AA is an area provided with a plurality of photodiodes PD (refer to
The gate line drive circuit 15 and the signal line selection circuit 16 are provided in the peripheral area GA. Specifically, the gate line drive circuit 15 is provided in an area of the peripheral area GA extending along a second direction Dy, and the signal line selection circuit 16 is provided in an area of the peripheral area GA extending along a first direction Dx and is provided between the sensor 10 and the detection circuit 48.
The first direction Dx is a direction in a plane parallel to the sensor base member 21. The second direction Dy is a direction in a plane parallel to the sensor base member 21 and is a direction orthogonal to the first direction Dx. The second direction Dy may intersect the first direction Dx without being orthogonal thereto. A third direction Dz is a direction orthogonal to the first direction Dx and the second direction Dy, and is the normal direction of the sensor base member 21.
The first light sources 61 are provided on the first light source base member 51 and are arranged along the second direction Dy. The second light sources 62 are provided on the second light source base member 52, and are arranged along the second direction Dy. The first light source base member 51 and the second light source base member 52 are electrically coupled through terminals 124 and 125, respectively, provided on the control board 121 to the control circuit 122 and the power supply circuit 123.
For example, inorganic light-emitting diodes (LEDs) or organic electroluminescent (EL) diodes (organic light-emitting diodes) (OLEDs) are used as the first light sources 61 and the second light sources 62. The first light sources 61 and the second light sources 62 emit first light L61 (refer to
The first light L61 emitted from the first light sources 61 is mainly reflected on a surface of a detection target object, for example, a finger Fg, and enters the sensor 10. Thus, the sensor 10 can detect a fingerprint by detecting a shape of asperities of the surface of, for example, the finger Fg. The second light L62 emitted from the second light sources 62 is mainly reflected inside, for example, the finger Fg, or transmitted through, for example, the finger Fg, and enters the sensor 10. Thus, the sensor 10 can detect biological information on the inside, for example, the finger Fg. The biological information is, for example, a pulse wave, pulsation, and a blood vessel image of the finger Fg or a palm.
As an example, the first light L61 may have a wavelength in a range from 520 nm to 600 nm, for example, at approximately 560 nm, and the second light L62 may have a wavelength in a range from 780 nm to 900 nm, for example, at approximately 850 nm. In this case, the first light L61 is blue or green visible light, and the second light L62 is infrared light. The sensor 10 can detect a fingerprint based on the first light L61 emitted from the first light sources 61. The second light L62 emitted from the second light sources 62 is reflected in the detection target object such as the finger Fg, or transmitted through or absorbed by, for example, the finger Fg, and enters the sensor 10. Thus, the sensor 10 can detect the pulse wave and the blood vessel image (vascular pattern) as the biological information on the inside, for example, the finger Fg.
Alternatively, the first light L61 may have a wavelength in a range from 600 nm to 700 nm, for example, at approximately 660 nm, and the second light L62 may have a wavelength in a range from 780 nm to 900 nm, for example, at approximately 850 nm. In this case, the sensor 10 can detect a blood oxygen saturation level in addition to the pulse wave, the pulsation, and the blood vessel image as the biological information based on the first light L61 emitted from the first light sources 61 and the second light L62 emitted from the second light sources 62. In this manner, since the detection device 1 includes the first light sources 61 and the second light sources 62, the detection device 1 can detect the various types of the biological information by performing the detection based on the first light L61 and the detection based on the second light L62.
The arrangement of the first light sources 61 and the second light sources 62 illustrated in
The sensor 10 is an optical sensor including the photodiodes PD serving as photoelectric conversion elements. Each of the photodiodes PD included in the sensor 10 outputs an electrical signal corresponding to light emitted thereto to the signal line selection circuit 16. The signal line selection circuit 16 sequentially selects a signal line SGL in response to a selection signal ASW from the detection controller 11. As a result, the electrical signal is output as a detection signal Vdet to the detector 40. The sensor 10 performs the detection in response to a gate drive signal Vgcl supplied from the gate line drive circuit 15.
The detection controller 11 is a circuit that supplies respective control signals to the gate line drive circuit 15, the signal line selection circuit 16, and the detector 40 to control operations thereof. The detection controller 11 supplies various control signals including, for example, a start signal STV, a clock signal CK, and a reset signal RST1 to the gate line drive circuit 15. The detection controller 11 also supplies various control signals including, for example, the selection signal ASW to the signal line selection circuit 16. The detection controller 11 also supplies various control signals to the first light sources 61 and the second light sources 62 to control to turn on and off the first light sources 61 and the second light sources 62.
The gate line drive circuit 15 is a circuit that drives a plurality of gate lines GCL (refer to
The signal line selection circuit 16 is a switch circuit that sequentially or simultaneously selects a plurality of signal lines SGL (refer to
The detector 40 includes the detection circuit 48, a signal processor 44, a coordinate extractor 45, a storage 46, a detection timing controller 47, an image processor 49, and an output processor 50. Based on a control signal supplied from the detection controller 11, the detection timing controller 47 controls the detection circuit 48, the signal processor 44, the coordinate extractor 45, and the image processor 49 so as to operate in synchronization with one another.
The detection circuit 48 is, for example, an analog front end (AFE) circuit. The detection circuit 48 is, for example, a signal processing circuit having functions of a detection signal amplifier 42 and an analog-to digital (A/D) converter 43. The detection signal amplifier 42 amplifies the detection signal Vdet. The A/D converter 43 converts an analog signal output from the detection signal amplifier 42 into a digital signal.
The signal processor 44 is a logic circuit that detects a predetermined physical quantity received by the sensor 10 based on an output signal of the detection circuit 48. When the finger Fg is in contact with or in proximity to the detection area AA, the signal processor 44 can detect the asperities on the surface of the finger Fg or the palm based on the signal from the detection circuit 48. The signal processor 44 can also detect the biological information based on the signal from the detection circuit 48. The biological information is, for example, the blood vessel image, a pulse wave, the pulsation, and/or the blood oxygen saturation level of the finger Fg or the palm.
In the case of obtaining the human blood oxygen saturation level, for example, 660 nm (the range is from 500 nm to 700 nm) is employed as the first light L61, and approximately 850 nm (the range is from 800 nm to 930 nm) is employed as the second light L62. Since the amount of light absorption changes with an amount of oxygen taken up by hemoglobin, the photodiode PD detects an amount of light obtained by subtracting the amount of light absorbed by the blood (hemoglobin) from that of each of the first light L61 and the second light L62 that have been emitted. Most of the oxygen in the blood is reversibly bound to hemoglobin in red blood cells, and a small portion of the oxygen is dissolved in blood plasma. More specifically, the value of percentage of oxygen with respect to an allowable amount thereof in the blood as a whole is called the oxygen saturation level (SpO2). The blood oxygen saturation level can be calculated from the amount of light obtained by subtracting the amount of light absorbed by the blood (hemoglobin) from that of the light emitted at the two wavelengths of the first light L61 and the second light L62.
The signal processor 44 may acquire the detection signals Vdet (biological information) simultaneously detected by the photodiodes PD, and average the detection signals Vdet. In this case, the detector 40 can perform the stable detection by reducing a measurement error caused by noise or a relative displacement between the detection target object such as the finger Fg and the sensor 10.
The storage 46 temporarily stores therein a signal calculated by the signal processor 44. The storage 46 may be, for example, a random access memory (RAM) or a register circuit.
The coordinate extractor 45 is a logic circuit that obtains, when the contact or the proximity of the finger is detected by the signal processor 44, detection coordinates of the asperities on the surface of, for example, the finger. The coordinate extractor 45 is also a logic circuit that obtains detected coordinates of blood vessels of the finger Fg or the palm. The image processor 49 combines the detection signals Vdet output from the respective photodiodes PD of the sensor 10 to generate two-dimensional information representing the shape of the asperities on the surface of, for example, the finger Fg and two-dimensional information representing a shape of the blood vessels of the finger Fg or the palm. The coordinate extractor 45 and the image processor 49 may be omitted.
The output processor 50 serves as a processor for performing processing based on the output from the photodiodes PD. Specifically, the output processor 50 of the embodiment outputs at least a sensor output Vo including at least pulse wave data based on the detection signal Vdet acquired through the signal processor 44. In the embodiment, the signal processor 44 outputs data indicating a variation (amplitude) in output of the detection signal Vdet of each of the photodiodes PD (to be described later), and the output processor 50 determines which output is to be employed as the sensor output Vo. However, the signal processor 44 or the output processor 50 may perform both the above-described operations. The output processor 50 may include, for example, the detected coordinates obtained by the coordinate extractor 45 and the two-dimensional information generated by the image processor 49 in the sensor output Vo. The function of the output processor 50 may be integrated in another component (for example, the image processor 49).
When the detection device of, for example, the pulse wave is mounted on a human body, noise is also detected associated with, for example, breathing, a change in attitude of the human body, and/or motion of the human body. Therefore, the signal processor 44 may be provided with a noise filter as required. The noise generated by the breathing and/or the change in attitude has frequency components of, for example, 1 Hz or lower, which are sufficiently lower than frequency components of the pulse wave. Therefore, the noise can be removed by using a band-pass filter as the noise filter. The band-pass filter may be provided, for example, in a detection signal amplifier 42. The frequency components of the noise generated by the motion of the human body are, for example, from several hertz to 100 hertz, and may overlap the frequency components of the pulse wave. In this case, however, the frequency is not constant and has a frequency fluctuation. Therefore, a noise filter is used that removes noise the frequencies of which have fluctuation components. As an example of a method for removing the frequencies having fluctuation components (first method for removing fluctuation components), a property may be used that a time lag of a peak value of the pulse wave occurs depending on the place of measurement of the human body. That is, the pulse wave has a time lag depending on the place of measurement of the human body, while the noise generated by the motion of the human body or the like has no time lag or a time lag smaller than that of the pulse wave. Therefore, the pulse wave is measured in at least two different places, and if peak values measured in the different places have occurred within a predetermined time, the pulse wave is removed as noise. Even in this case, a case can be considered where the waveform caused by noise accidentally overlaps the waveform caused by the pulse wave. However, in this case, the two waveforms overlap each other at only one place of the different places. Therefore, the waveform caused by noise can be distinguished from the waveform caused by the pulse wave. For example, the signal processor 44 can perform this processing. As another example of the method for removing the frequencies having fluctuation components (second method for removing fluctuation components), the signal processor 44 removes frequency components having different phases. In this case, for example, a short-time Fourier transform may be performed to remove the fluctuation components, and then, an inverse Fourier transform may be performed. Moreover, a commercial frequency power supply (50 Hz or 60 Hz) also serves as a noise source. However, in this case as well, in the same manner as the noise generated by the motion of the human body or other factors, the peak values measured at the different places have no time lag therebetween or a time lag therebetween smaller than that of the pulse wave. Therefore, the noise can be removed using the same method as the above-described first method for removing fluctuation components. Alternatively, the noise generated by the commercial frequency power supply may be removed by providing a shield on a surface on the opposite side of a detection surface of a detecting element.
The following describes a circuit configuration example of the detection device 1.
As illustrated in
The gate lines GCL extend in the first direction Dx, and are coupled to the partial detection areas PAA arranged in the first direction Dx. A plurality of gate lines GCL(1), GCL(2), . . . , GCL(8) are arranged in the second direction Dy, and are each coupled to the gate line drive circuit 15. In the following description, the gate lines GCL(1), GCL(2), . . . , GCL(8) will each be simply referred to as the gate line GCL when they need not be distinguished from one another. For ease of understanding of the description,
The signal lines SGL extend in the second direction Dy and are coupled to the photodiodes PD of the partial detection areas PAA arranged in the second direction Dy. A plurality of signal lines SGL(1), SGL(2), . . . , SGL(12) are arranged in the first direction Dx, and are each coupled to the signal line selection circuit 16 and a reset circuit 17. In the following description, the signal lines SGL(1), SGL(2), . . . , SGL(12) will each be simply referred to as the signal line SGL when need not be distinguished from one another.
For ease of understanding of the description, 12 of the signal lines SGL are illustrated. However, this is merely an example, and N signal lines SGL (where N is 12 or larger, and is, for example, 252) may be arranged. The resolution of the sensor is, for example, 508 dots per inch (dpi), and the number of cells is 252×256. In
The gate line drive circuit 15 receives the various control signals such as the start signal STV, the clock signal CK, and the reset signal RST1 from the control circuit 122 (refer to
The gate line drive circuit 15 may perform different driving for each of detection modes including the detection of a fingerprint and the detection of different items of the biological information (such as the pulse wave, the pulsation, the blood vessel image, and the blood oxygen saturation level). For example, the gate line drive circuit 15 may drive more than one gate line GCL collectively.
Specifically, the gate line drive circuit 15 may simultaneously select a predetermined number of the gate lines GCL from among the gate lines GCL(1), GCL(2), . . . , GCL(8) based on the control signals. For example, the gate line drive circuit 15 simultaneously selects six gate lines GCL(1) to GCL(6) and supplies thereto the gate drive signals Vgcl. The gate line drive circuit 15 supplies the gate drive signals Vgcl through the selected six gate lines GCL to the first switching elements Tr. Through this operation, group areas PAG1 and PAG2 each including more than one partial detection area PAA arranged in the first direction Dx and the second direction Dy are selected as the respective detection targets. The gate line drive circuit 15 drives the predetermined number of the gate lines GCL collectively, and sequentially supplies the gate drive signals Vgcl to the gate lines GCL in units of the predetermined number of the gate lines GCL. Hereinafter, when positions of different group areas such as the group areas PAG1 and PAG2 are not distinguished from each other, each of the group areas will be called “group area PAG”.
The signal line selection circuit 16 includes a plurality of selection signal lines Lsel, a plurality of output signal lines Lout, and third switching elements TrS. The third switching elements TrS are provided correspondingly to the signal lines SGL. Six signal lines SGL(1), SGL(2), . . . , SGL(6) are coupled to a common output signal line Lout1. Six signal lines SGL(7), SGL(8), . . . , SGL(12) are coupled to a common output signal line Lout2. The output signal lines Lout1 and Lout2 are each coupled to the detection circuit 48.
The signal lines SGL(1), SGL(2), . . . , SGL(6) are grouped into a first signal line block, and the signal lines SGL(7), SGL(8), . . . , SGL(12) are grouped into a second signal line block. The selection signal lines Lsel are coupled to the gates of the third switching elements TrS included in one of the signal line blocks, respectively. One of the selection signal lines Lsel is coupled to the gates of the third switching elements TrS in the signal line blocks.
Specifically, selection signal lines Lsel1, Lsel2, . . . , Lsel6 are coupled to the third switching elements TrS corresponding to the signal lines SGL(1), SGL(2), . . . , SGL(6), respectively. The selection signal line Lsel1 is coupled to the third switching element TrS corresponding to the signal line SGL(1) and the third switching element TrS corresponding to the signal line SGL(7). The selection signal line Lsel2 is coupled to the third switching element TrS corresponding to the signal line SGL(2) and the third switching element TrS corresponding to the signal line SGL(8).
The control circuit 122 (refer to
The signal line selection circuit 16 may couple more than one signal line SGL to the detection circuit 48 collectively. Specifically, the control circuit 122 (refer to
By the operations of the gate line drive circuit 15 and the signal line selection circuit 16, the detection is performed for each group area PAG. As a result, the intensity of the detection signal Vdet obtained by one time of detection increases, so that the sensor sensitivity can be improved. In addition, time required for the detection can be reduced. Consequently, the detection device 1 can repeatedly perform the detection in a short time, and thus, can improve a signal-to-noise (S/N) ratio, and can accurately detect a change in the biological information with time, such as the pulse wave.
As illustrated in
The control circuit 122 supplies a reset signal RST2 to the reset signal line Lrst. This operation turns on the fourth switching elements TrR to electrically couple the signal lines SGL to the reference signal line Lvr. The power supply circuit 123 supplies a reference signal COM to the reference signal line Lvr. This operation supplies the reference signal COM to a capacitive element Ca (refer to
As illustrated in
The gates of the first switching elements Tr belonging to the partial detection areas PAA arranged in the first direction Dx are coupled to the gate line GCL. The sources of the first switching elements Tr belonging to the partial detection areas PAA arranged in the second direction Dy are coupled to the signal line SGL. The drain of the first switching element Tr is coupled to the cathode of the photodiode PD and the capacitive element Ca.
The anode of the photodiode PD is supplied with the sensor power supply signal VDDSNS from the power supply circuit 123. The signal line SGL and the capacitive element Ca are supplied with the reference signal COM that serves as an initial potential of the signal line SGL and the capacitive element Ca from the power supply circuit 123.
When the partial detection area PAA is irradiated with light, a current corresponding to an amount of light flows through the photodiode PD. As a result, an electrical charge is stored in the capacitive element Ca. After the first switching element Tr is turned on, a current corresponding to the electrical charge stored in the capacitive element Ca flows through the signal line SGL. The signal line SGL is coupled to the detection circuit 48 through a corresponding one of the third switching elements TrS of the signal line selection circuit 16. Thus, the detection device 1 can detect a signal corresponding to the amount of the light irradiating the photodiode PD in each of the partial detection areas PAA or signals corresponding to the amounts of the light irradiating the photodiodes PD in each group area PAG.
During a reading period Pdet (refer to
The following describes a configuration of the photodiode PD.
As illustrated in
The TFT layer 22 is used for circuits such as the gate line drive circuit 15 and the signal line selection circuit 16 described above. The TFT layer 22 is also provided with thin-film transistors (TFTs), such as the first switching element Tr, and various types of wiring, such as the gate lines GCL and the signal lines SGL. The sensor base member 21 and the TFT layer 22, which serve as a drive circuit board that drives the sensor for each predetermined detection area, are also called a backplane.
The insulating layer 23 is an inorganic insulating layer. For example, an oxide such as silicon oxide (SiO2) or a nitride such as silicon nitride (SiN) is used as the insulating layer 23.
The photodiode PD is provided on the insulating layer 23. The photodiode PD includes a photoelectric conversion layer 31, a cathode electrode 35, and an anode electrode 34. The cathode electrode 35, the photoelectric conversion layer 31, and the anode electrode 34 are stacked in the order as listed, in a direction orthogonal to the first surface S1 of the sensor base member 21. The stacking order in the photodiode PD may be as follows: the anode electrode 34, the photoelectric conversion layer 31, and the cathode electrode 35.
Characteristics (such as a voltage-current characteristic and a resistance value) of the photoelectric conversion layer 31 vary depending on the irradiated light. An organic material is used as the material of the photoelectric conversion layer 31. Specifically, a low-molecular organic material such as C60 (fullerene), phenyl-C61-butyric acid methyl ester (PCBM), copper phthalocyanine (CuPc), fluorinated copper phthalocyanine (F16CuPc), rubrene (5,6,11,12-tetraphenyltetracene), or PDI (derivative of perylene) can be used as the photoelectric conversion layer 31.
The photoelectric conversion layer 31 can be formed by a vapor deposition method (dry process) using any of the above-listed low-molecular organic materials. In this case, the photoelectric conversion layer 31 may be a laminated film of CuPc and F16CuPc, or a laminated film of rubrene and C60. The photoelectric conversion layer 31 can also be formed by an application method (wet process). In this case, a material obtained by combining any of the above-listed low-molecular organic materials with a polymeric organic material is used as the photoelectric conversion layer 31. For example, poly(3-hexylthiophene) (P3HT) or F8-alt-benzothiadiazole (F8BT) can be used as the polymeric organic material. The photoelectric conversion layer 31 can be a film in a state of a mixture of P3HT and PCBM, or a film in a state of a mixture of F8BT and PDI.
The cathode electrode 35 faces the anode electrode 34 with the photoelectric conversion layer 31 interposed therebetween. A light-transmitting conductive material such as indium tin oxide (ITO) is used as the anode electrode 34. A metal material such as silver (Ag) or aluminum (Al) is used as the cathode electrode 35. Alternatively, the cathode electrode 35 may be an alloy material containing at least one or more of these metal materials.
The cathode electrode 35 can be formed as a light-transmitting transflective electrode by controlling the film thickness of the cathode electrode 35. For example, the cathode electrode 35 is formed of an Ag thin film having a film thickness of 10 nm so as to have light transmittance of approximately 60%. In this case, the photodiode PD can detect light emitted from both surface sides of the sensor base member 21, for example, both the first light L61 emitted from the first surface S1 side and the second light L62 emitted from the second surface S2 side.
The protection film 24 is provided so as to cover the anode electrode 34. The protection film 24 is a passivation film and is provided to protect the photodiode PD.
The horizontal axis of the graph illustrated in
As illustrated in
The following describes an operation example of the detection device 1.
During the reset period Prst, the gate line drive circuit 15 sequentially selects each of the gate lines GCL based on the start signal STV, the clock signal CK, and the reset signal RST1. The gate line drive circuit 15 sequentially supplies the gate drive signals Vgcl {Vgcl(1) to Vgcl(M)} to the gate lines GCL. The gate drive signal Vgcl has a pulsed waveform having a power supply voltage VDD serving as a high-level voltage and a power supply voltage VSS serving as a low-level voltage. In
Thus, during the reset period Prst, the capacitive elements Ca of all the partial detection areas PAA are sequentially electrically coupled to the signal lines SGL, and are supplied with the reference signal COM. As a result, the electrical charges stored in the capacitance of the capacitive elements Ca are reset. The capacitance of the capacitive elements Ca of some of the partial detection areas PAA can be reset by partially selecting the gate lines and the signal lines SGL.
Examples of the exposure timing control method include a control method of exposure during scanning time of gate line and a full-time control method of exposure. In the control method of exposure during scanning time of gate line, the gate drive signals {Vgcl(1) to Vgcl(M)} are sequentially supplied to all the gate lines GCL coupled to the photodiodes PD serving as the detection targets, and all the photodiodes PD serving as the detection targets are supplied with the reset voltage. Then, after all the gate lines GCL coupled to the photodiodes PD serving as the detection targets are set to a low voltage (the first switching elements Tr are turned off), the exposure starts, whereby the exposure is performed during the effective exposure period Pex. After the exposure ends, the gate drive signals {Vgcl(1) to Vgcl(M)} are sequentially supplied to the gate lines GCL coupled to the photodiodes PD serving as the detection targets as described above and reading is performed during the reading period Pdet. In the full-time control method of exposure, control for performing the exposure can also be performed during the reset period Prst and the reading period Pdet (full-time exposure control). In this case, the effective exposure period Pex(1) starts after the gate drive signal Vgcl(M) is supplied to the gate line GCL. The term “effective exposure periods Pex{(1), . . . , (M)}” refers to a period during which the capacitive elements Ca are charged from the photodiodes PD. The start timing and the end timing of the actual effective exposure periods Pex(1), . . . , Pex(M) are different among the partial detection areas PAA corresponding to the gate lines GCL. Each of the effective exposure periods Pex(1), . . . , Pex(M) starts when the gate drive signal Vgcl changes from the power supply voltage VDD serving as the high-level voltage to the power supply voltage VSS serving as the low-level voltage during the reset period Prst. Each of the effective exposure periods Pex(1), . . . , Pex(M) ends when the gate drive signal Vgcl changes from the power supply voltage VSS to the power supply voltage VDD during the reading period Pdet. The lengths of the exposure time of the effective exposure periods Pex(1), . . . , Pex(M) are equal.
In the control method of exposure during scanning time of gate line, a current flows corresponding to the light irradiating the photodiode PD in each of the partial detection areas PAA during the effective exposure periods Pex{(1), . . . , (M)}. As a result, an electrical charge is stored in each of the capacitive elements Ca.
At a time before the reading period Pdet starts, the control circuit 122 sets the reset signal RST2 to a low-level voltage. This operation stops operation of the reset circuit 17. The reset signal may be set to a high-level voltage only during the reset period Prst. During the reading period Pdet, the gate line drive circuit 15 sequentially supplies the gate drive signals Vgcl(1) . . . , Vgcl(M) to the gate lines GCL in the same manner as during the reset period Prst.
Specifically, the gate line drive circuit 15 supplies the gate drive signal Vgcl(1) at the high-level voltage (power supply voltage VDD) to the gate line GCL(1) during a period V(1). The control circuit 122 sequentially supplies the selection signals ASW1, . . . , ASW6 to the signal line selection circuit 16 during a period in which the gate drive signal Vgcl(1) is at the high-level voltage (power supply voltage VDD). This operation sequentially or simultaneously couples the signal lines SGL of the partial detection areas PAA selected by the gate drive signal Vgcl(1) to the detection circuit 48. As a result, the detection signal Vdet for each of the partial detection areas PAA is supplied to the detection circuit 48. A time of, for example, approximately 20 μs (substantially 20 μs) elapses from when the gate drive signal Vgcl(1) is set to the high level to when the first selection signal ASW1 starts to be supplied, and a time of, for example, approximately 60 μs (substantially 60 μs) elapses while each of the selection signals ASW1, . . . , ASW6 is supplied. Such a high-speed response can be achieved by using thin-film transistors (TFTs) made using low-temperature polysilicon (LTPS) having mobility of substantially 40 cm2/Vs.
In the same manner, the gate line drive circuit 15 supplies the gate drive signals Vgcl(2), . . . , Vgcl(M−1), Vgcl(M) at the high-level voltage to gate lines GCL(2), . . . , GCL(M−1), GCL(M) during periods V(2), . . . , V(M−1), V(M), respectively. That is, the gate line drive circuit 15 supplies the gate drive signal Vgcl to the gate line GCL during each of the periods V(1), V(2), . . . , V(M−1), V(M). The signal line selection circuit 16 sequentially selects each of the signal lines SGL based on the selection signal ASW in each period in which the gate drive signal Vgcl is set to the high-level voltage. The signal line selection circuit 16 sequentially couples each of the signal lines SGL to one detection circuit 48. Thus, the detection device 1 can output the detection signals Vdet of all the partial detection areas PAA to the detection circuit 48 during the reading period Pdet.
As illustrated in
Specifically, after the period t4 starts in which the switch SSW is on, the electrical charge moves from the capacitor (capacitive element Ca) of the partial detection area PAA to the capacitor (capacitive element Cb) of the detection signal amplifier 42 of the detection circuit 48. At this time, the non-inverting input (+) of the detection signal amplifier 42 is biased to the reference potential (Vref) voltage (for example, 0.75 [V]). As a result, the output (Vout) of the third switching element TrS is also set to the reference potential (Vref) voltage due to the imaginary short-circuit between input ends of the detection signal amplifier 42. The voltage of the capacitive element Cb is set to a voltage corresponding to the electrical charge stored in the capacitor (capacitive element Ca) of the partial detection area PAA at a location where the third switching element TrS is turned on in response to the selection signal ASW(k). After the output (Vout) of the third switching element TrS is set to the reference potential (Vref) voltage due to the imaginary short-circuit, the output of the detection signal amplifier 42 reaches a capacitance corresponding to the voltage of the capacitive element Cb, and this output voltage is read by the A/D converter 43. The voltage of the capacitive element Cb is, for example, a voltage between two electrodes in a capacitor constituting the capacitive element Cb.
The period t1 is, for example, 20 [μs]. The period t2 is, for example, 60 [μs]. The period t3 is, for example, 44.7 [μs]. The period t4 is, for example, 0.98 [μs].
Although
The following describes an operation example of the sensor 10, the first light sources 61, and the second light sources 62.
As illustrated in
During the period t(1), the second light sources 62 are on, and the first light sources 61 are off. As a result, in the detection device 1, currents flow from the photodiodes PD through the signal lines SGL to the detection circuit 48 based on the second light L62 emitted from the second light sources 62. During the period t(2), the first light sources 61 are on, and the second light sources 62 are off. As a result, in the detection device 1, currents flow from the photodiodes PD through the signal lines SGL to the detection circuit 48 based on the first light L61 emitted from the first light sources 61. In the same manner, during the period t(3), the second light sources 62 are on, and the first light sources 61 are off; and during the period t(4), the first light sources 61 are on, and the second light sources 62 are off.
In this manner, the first light sources 61 and the second light sources 62 are caused to be on in a time-division manner at intervals of the period t. This operation outputs the first detection signals detected by the photodiodes PD based on the first light L61 and the second detection signals detected by the photodiodes PD based on the second light L62 to the detection circuit 48 in a time-division manner. Consequently, the first detection signals and the second detection signals are restrained from being output to the detection circuit 48 in a mutually superimposed manner. As a result, the detection device 1 can well detect the various types of the biological information.
The driving method of the first light sources 61 and the second light sources 62 can be changed as appropriate. For example, in
The lighting operations are not limited to the example illustrated in
In the case of detecting the pulse wave, the second light sources 62 preferably emit infrared light. Specifically, as described above, the second light L62 may have a wavelength in a range from 780 nm to 900 nm, for example, at approximately 850 nm, or may have a wavelength in a range from 800 nm to 930 nm. In the case of detecting the pulse wave, the wavelength of the second light L62 from the second light sources 62 only needs to be in a range from 500 nm to 950 nm.
As described with reference to
As illustrated in
In the reset period Prst illustrated in
When the reset period Prst and the reading period Pdet overlap the lighting period of the light sources as illustrated in
As described above, when the reset period Prst and the reading period Pdet overlap the lighting period of the light sources as illustrated in
During the reading period Pdet, the gate drive signal Vgcl is supplied to the gate lines GCL, such as the gate lines GCL(1), GCL(2), . . . , GCL(M), arranged in the second direction Dy at different timings from one another, and as a result, the temporal shifts of the output timings occur between the photodiodes PD(1), PD(2), . . . , PD(M). The output of the photodiode PD refers to an output based on the capacitance of the capacitive element Ca of the partial detection area PAA provided with the photodiode PD.
In the reading period Pdet, the fall of the pulse of the gate drive signal Vgcl supplied to each of the photodiodes PD(1), PD(2), . . . , PD(M) is defined as the end of a corresponding one of the effective exposure periods Pex{(1), . . . , (M)}. The rise of the pulse is defined as the start timing of the output of the photodiode PD, and the fall of the pulse is defined as the end timing of the output of the photodiode PD. When the fall of the pulse is defined as the completion timing of the output of the photodiode PD, the temporal shift of the completion timing of the output can be represented by a shift of the timing of the fall of the pulse. The degree of temporal shift of the completion timing of the output is maximized between the photodiode PD(1) and the photodiode PD(M).
As described above, when the reset period Prst and the reading period Pdet overlap the lighting period of the light sources as illustrated in
Specifically, even in the example illustrated in
When the reset period Prst and the reading period Pdet do not overlap the lighting period of the second light sources 62 as illustrated in
In this manner, regardless of the relation of the reset period Prst and the reading period Pdet with the lighting period of the second light sources 62, the temporal shift of the completion timing of the output, such as the time InB(M), occurs due to the shift of the supply timing of the gate drive signal Vgcl. If the time stamp is provided for each of the photodiodes PD{(1), . . . , (M)} corresponding to the gate lines GCL{(1), . . . , (M)}, when the pulse wave velocity is calculated based on the pulsation represented by the output of each of the photodiodes PD(1), PD(2), . . . , PD(M) without taking into account the temporal shift of the completion timing of the output, the calculated pulse wave velocity includes an error caused by the temporal shift of the completion timing of the output. Therefore, in this case, in calculating the pulse wave, the temporal shifts of the output timing of the photodiodes PD(1), PD(2), . . . , PD(M) are corrected based on the supply timing of the gate drive signal Vgcl to the gate lines GCL(1), GCL(2), . . . , GCL(M).
The relation of the reset period Prst and the reading period Pdet with the lighting period of the second light sources 62 influences whether the shift of the supply timing of the gate drive signal Vgcl causes the temporal shift of the effective exposure period Pex of each of the photodiodes PD(1), PD(2), . . . , PD(M). Thus, in the embodiment in which the reset period Prst and the reading period Pdet overlap the lighting period of the second light sources 62 (refer to
The threshold of amplitude is set, based on tests in advance or the like, as such a value that the amplitude of output values obtained by processing the peak U1, the bottom D1, the peak U2, and the bottom D2 illustrated in
To detect and determine such amplitude of the output, the output is held on a predetermined period (for example, four seconds) basis. Although, for example, the storage 46 is used to hold such an output, the present embodiment is not limited thereto. A storage device or a storage circuit only needs to be provided that can be referred to by a component for determining the pulsation. For example, a storage for holding the output may be provided that can be used by the output processor 50.
Although a peak of the output such as the peak U1 or U2, or a bottom of the output such as the bottom D1 or D2 serves as a trigger for counting the timing of the pulsation, the present embodiment is not limited thereto. Any timing in a period in which the amplitude of the output is generated can serve as the count timing of the pulsation.
Before correction of the output, a temporal shift indicated by time BR1 occurs between the peak U1 of the output of the photodiode PD(1) and a peak U3a of the output of the photodiode PD(M). Before correction of the output, a temporal shift indicated by time BR2 occurs between the bottom D2 of the output of the photodiode PD(1) and a bottom D3a of the output of the photodiode PD(M). Each of the times BR2 and BR1 includes the temporal shift generated in accordance with the temporal shift of the supply timing of the gate drive signal Vgcl described with reference to
Thus, in the embodiment, the times BR1 and BR2 are corrected such that the temporal shift between the pulsation timing represented by the output of the photodiode PD(1) and the pulsation timing represented by the output of the photodiode PD(M) is equal to a temporal shift corresponding to the distance between the photodiode PD(1) and the photodiode PD(M). For the correction, the correction value is obtained from a relation among the scan speed of the gate lines GCL, the distance in the vascular pattern, and the angle between the extension direction at each of the positions of the vascular pattern and the scan direction. For example, if the extension direction between two points (for example, the photodiode PD(1) and the photodiode PD(M)) of the vascular pattern is the same as the scan direction (second direction Dy) of the gate lines GCL, the correction value only needs to be obtained by simply dividing the distance between the two points (of the vascular pattern) by the shift time. Herein, the term “shift time” refers to a shift time between pulse waves detected at the two points that is derived as a result of the correction of the temporal shift described above. That is, the “shift time” is a “shift time” when the same pulse wave is assumed to be observed at the two points with the “shift time” interposed therebetween while the pulse wave propagates. When the vascular pattern between the two points includes portions forming an angle with the scan direction (second direction Dy), the distance between the two points (of the vascular pattern) is further divided by the tangent of the average of the angles (tan θ).
For example, when the reset period Prst and the reading period Pdet overlap the lighting period of the second light sources 62 as described with reference to
When the reset period Prst and the reading period Pdet do not overlap the lighting period of the second light sources 62 as described with reference to
When the photodiode PD(1) is provided at the point P5 (refer to
γ=α/(1000/β) (1)
Each of the times AR1 and AR2 is a time generated by a temporal shift corresponding to the distance between the photodiode PD(1) and the photodiode PD(M). Thus, the pulse wave velocity in the second direction Dy between the photodiode PD(1) and the photodiode PD(M) can be calculated based on the relation of the distance between the photodiode PD(1) and the photodiode PD(M) with each of the times AR1 and AR2.
While the correction has been described above as an example of the relation between the photodiode PD(1) and the photodiode PD(M), the pulse wave velocity between the photodiodes PD(1), PD(2), . . . , PD(M) can be calculated by individually applying the correction using the same approach to the temporal shift of the output of each of the photodiodes PD(1), PD(2), . . . , PD(M).
The above describes the temporal shifts between the partial detection areas PAA that are arranged in the second direction Dy and differ from one another in supply timing of the gate drive signal Vgcl. In the same manner, the correction can be performed on the temporal shifts caused by the selection signals ASW (refer to
While the description with reference to
Although the above description with reference to
For example, the output processor 50 calculates the pulse wave. In this case, for example, an output for a predetermined time stored in the storage 46 is given to the output processor 50 through the signal processor 44, and as a result, the output processor 50 detects the amplitude between a peak and a bottom of the output of each of the photodiodes PD to identify the count timing of the pulsation. The output processor 50 uses the above-described approach to correct the temporal shift of each of the photodiodes PD, and calculates the pulse wave velocity based on the relation of the distance between the photodiodes PD with the count timing of the pulsation based on the output of each of the photodiodes PD. Another component may be used to calculate the pulse wave velocity. For example, the output processor 50 may output data representing the output of each of the photodiodes PD obtained on a predetermined period basis, to an external information processing device or information processing circuit. In this case, the external information processing device or information processing circuit calculates the pulse wave velocity.
In the above description, the blood vessel VB is employed to calculate the pulse wave velocity. The type of the blood vessel VB is not limited to a particular type, such as an artery, a vein, or other.
As described above, the detection device 1 of the embodiment includes the first optical sensor (for example, the photodiode PD(1) at the point P5), the second optical sensor (for example, the photodiode PD(M) at the point P2) disposed at a predetermined distance (for example, the distance In) from the first optical sensor, the light sources (for example, the second light sources 62) that emit light to be detected by the first optical sensor and the second optical sensor facing the living body tissue including the blood vessel (for example, the blood vessel VB), and a processor (for example, the output processor 50) that calculates the pulse wave velocity of the blood vessel based on a time-series variation of the output of the first optical sensor, a time-series variation of the output of the second optical sensor, and the predetermined distance. The time-series variation of the output refers to a time-series variation of the output including the amplitude, such as the peak U1, the bottom D1, the peak U2, the bottom D2, and so on, described with reference to
As control in the embodiment, control can be employed in which the period in which the first optical sensor (for example, the photodiode PD(1) at the point P5) and the second optical sensor (for example, the photodiode PD(M) at the point P2) are reset (reset period Prst), the period in which the light sources are on (effective exposure period Pex), and the period in which the output from the first optical sensor and the output from the second optical sensor are acquired (reading period Pdet) are independent from one another. This control can reduce the amount of correction of the temporal shift in the calculation of the pulse wave velocity.
As the control in the embodiment, control can also be employed in which the period in which the light sources are on (effective exposure period Pex) overlaps the period in which the first optical sensor (for example, the photodiode PD(1) at the point P5) and the second optical sensor (for example, the photodiode PD(M) at the point P2) are reset (reset period Prst) and the period in which the output from the first optical sensor and the output from the second optical sensor are acquired (reading period Pdet). This control can ensure the longer effective exposure period Pex while shortening one period including the reset period Prst, the reading period Pdet, and the effective exposure period Pex. In this case, first reset timing of resetting the first optical sensor (for example, the photodiode PD(1) at the point P5) differs from second reset timing of resetting the second optical sensor (for example, the photodiode PD(M) at the point P2) (refer to
First acquisition timing of acquiring the output from the first optical sensor (for example, the photodiode PD(1) at the point P5) differs from second acquisition timing of acquiring the output from the second optical sensor (for example, the photodiode PD(M) at the point P2) (refer to
Each of the first optical sensor and the second optical sensor includes a plurality of optical sensors (for example, the group areas PAG). This configuration can easily increase the output of each of the first optical sensor and the second optical sensor.
The wavelength of the second light L62 is in a range from 500 nm to 950 nm. As a result, the pulsation of the blood vessel VB can be better detected.
The processor (for example, the output processor 50) determines an occurrence of the pulse based on a relation of the degree of amplitude of the output in the time-series variation of the output of the first optical sensor (for example, the photodiode PD(1) at the point P5) and the time-series variation of the output of the second optical sensor (for example, the photodiode PD(M) at the point P2) with the predetermined amplitude reference value (for example, the threshold). As a result, a change in the detection of the optical sensor caused by the pulsation of the blood vessel (for example, the blood vessel VB) can be used for detecting the occurrence of the pulse.
The processor (for example, the output processor 50) identifies an occurrence of a peak (for example, the peak U1) or a bottom (for example, the bottom D1) in one cycle of the amplitude included in the time-series variation of the output of the first optical sensor (for example, the photodiode PD(1) at the point P5) and the time-series variation of the output of the second optical sensor (for example, the photodiode PD(M) at the point P2) as the occurrence of one pulse. As a result, the number of times of occurrence of pulse can be more easily counted.
The specific form of the detection device 1 is not limited to the form described with reference to
The detection device 1 can be mounted on various products supposed to be in contact with or in proximity to the living body tissue. Mounting examples of the detection device 1 will be described with reference to
In the embodiment, the case has been described where the gate line drive circuit 15 performs the time-division selective driving of sequentially supplying the gate drive signals Vgcl to the gate lines GCL. However, the driving method is not limited to this case. The sensor 10 may perform code division selection driving (hereinafter, called “code division multiplexing (CDM) driving”) to perform the detection. Since the CDM driving and a drive circuit thereof are described in Japanese Patent Application No. 2018-005178 (JP-A-2018-005178), what is described in JP-A-2018-005178 is included in the embodiment, and the description will not be omitted herein.
Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above. The content disclosed in the embodiment is merely an example, and can be variously modified within the scope not departing from the gist of the present invention. Any modifications appropriately made within the scope not departing from the gist of the present invention also naturally belong to the technical scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-078925 | Apr 2019 | JP | national |
This application claims the benefit of priority from Japanese Patent Application No. 2019-078925 filed on Apr. 17, 2019 and International Patent Application No. PCT/JP2020/016503 filed on Apr. 15, 2020, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2020/016503 | Apr 2020 | US |
| Child | 17500179 | US |
