Sensor device

Abstract

This sensor device comprises a sensor unit (2), a switch circuit (4), an amplifier circuit (5), and a control unit (8). The sensor unit (2) is provided with a plurality of sensor elements (20). The switch circuit (4) is provided with a plurality of switches (21) respectively connected to the plurality of sensor elements (20). Each of the plurality of switches (21) is capable of switching between a plurality of first pathways and a plurality of second pathways. The amplifier circuit (5) comprises: a plurality of amplifiers (22) respectively connected to the plurality of first pathways of the plurality of switches (21); and an amplifier (24) connected in common to the plurality of second pathways of the plurality of switches (21). The control unit (8) controls the switch circuit (4) so as to respectively connect the plurality of sensor elements (20) and the plurality of amplifiers (22) in a first mode, and controls the switch circuit (4) so as to connect two or more sensor elements (20) and the amplifier (24) in common in a second mode.

Description

Sensor Device

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

[0002] Sensor devices that utilize the piezoelectric effect to detect various pressures are currently in use. Piezoelectric sensors as sensor devices change their charge amount in response to pressure, and detect this change in charge amount as an electrical signal. When the pressure or vibration is minute, the charge amount is also small, so it is necessary to process the signal to a level that can be identified by a general electrical circuit in the subsequent stage, and to improve noise resistance against power supply noise, etc. In order to expand the dynamic range that piezoelectric sensors can detect, from minute pressures to large pressures, improvements are required in the detection and control methods.

[0003] Patent Document 1 discloses a wristwatch with a function for measuring pulse as biological information. In Patent Document 1, a band is attached to the wrist over an artery, an air chamber is provided within the band, and the pulse is detected from fluctuations in air pressure. Patent Document 2 discloses a motion sensor that detects the movement of tendons in the wrist using a strain sensor equipped with multiple sensors. The detection methods disclosed in Patent Documents 1 and 2 can detect pulse (micro signals) and tendon movement (large signals) separately, but it is difficult to detect signals over a dynamic range that covers from micro signals to large signals.

[0004] Patent Document 3 discloses a sensor device in which a sensor unit is attached to the front surface of the wrist and detects pressure fluctuations from the blood vessels in the wrist via a transmission member. When measuring the pulse of an artery in the wrist, the pressure applied to the sensor unit is very small. Therefore, if the sensor unit and the object to be measured (e.g., an artery) are misaligned, it becomes difficult to detect the pressure. To accurately measure the pulse, it is time-consuming to align the sensor unit with the object to be measured. Furthermore, as in Patent Document 3, a specific transmission member must be added.

[0005] Piezoelectric sensors using organic piezoelectric materials such as P(VDF / TrFE) are also being used. Because organic piezoelectric materials can be applied by coating, can be produced using low-temperature processes, and are easily formed into films, attempts are being made to apply them to flexible sensors for wearable devices and large-area sensors. Flexible piezoelectric sensors are attracting attention as a technology with a variety of potential applications, including biosensors for measuring pulse waves and mechanomyograms, and tactile sensors. Piezoelectric sensors are also expected to be effectively used in a variety of fields, including medicine, healthcare, monitoring, sports, gesture UI, robotics, and facility monitoring.

[0006] One application of piezoelectric sensors is pulse diagnosis, which involves taking the patient's pulse with the fingers at their wrist and examining the pulse's characteristics, such as its rate, strength, and rhythm, to diagnose abnormalities in the internal organs and meridians, and also to help diagnose the location, symptoms, and prognosis of the disease.

[0007] Pulse diagnosis is a method that allows for the diagnosis of abnormalities in a patient's internal organs and meridians simply by measuring the pulse at the wrist, but this diagnosis is based on intuition and cannot be quantified, and currently relies heavily on the skill and experience of the examiner. Furthermore, if one were to create a measuring device to quantify these, it would require a sensor to measure the pulse, a sensor to measure the pressure of the finger, and a device to apply pressure.

[0008] JP 2005-185631 A, International Publication No. 2022 / 130684, Japanese Patent Application Laid-Open No. 2020-156659, Japanese Patent Application Laid-Open No. 2020-74940, International Publication No. 2014 / 181467, Japanese Patent Application Laid-Open No. 2000-5139

[0009] The present disclosure provides a sensor device capable of improving the dynamic range.

[0010] According to a first aspect of the present invention, there is provided a sensor device comprising: a sensor unit including a plurality of sensor elements; a switch circuit including a plurality of first switches connected to the plurality of sensor elements, each of the plurality of first switches being switchable between a plurality of first paths and a plurality of second paths; an amplifier circuit including a plurality of first amplifiers connected to the plurality of first paths of the plurality of first switches, respectively, and a second amplifier connected in common to the plurality of second paths of the plurality of first switches; and a control unit that executes a first mode and a second mode, wherein in the first mode, the control unit controls the switch circuit to connect the plurality of sensor elements to the plurality of first amplifiers, respectively, and in the second mode, controls the switch circuit to connect two or more sensor elements of the plurality of sensor elements to the second amplifier in common.

[0011] According to a second aspect of the present invention, there is provided a sensor device according to the first aspect, wherein the control unit selects the first mode when the voltage amplitude of at least one of the plurality of detection signals of the plurality of sensor elements is greater than a first threshold, and selects the second mode when the voltage amplitude of at least one of the plurality of detection signals is equal to or less than the first threshold.

[0012] According to a third aspect of the present invention, there is provided the sensor device according to any one of the above aspects, wherein the control unit switches between the first mode and the second mode based on a request from an external device.

[0013] According to a fourth aspect of the present invention, there is provided a sensor device according to any of the above aspects, further comprising a plurality of first load resistors connected to the inputs of the plurality of first amplifiers respectively, and a second load resistor connected to the input of the second amplifier.

[0014] According to a fifth aspect of the present invention, there is provided a sensor device according to any of the above aspects, further comprising a plurality of first load resistors respectively connected to the inputs of the plurality of first amplifiers, a second switch connected to the input of the second amplifier and switchable between a first path and a second path, a second load resistor connected to the first path of the second switch, and a third load resistor connected to the second path of the second switch and having a resistance value greater than that of the second load resistor, wherein the control unit controls the second switch based on the output voltage of the second amplifier.

[0015] According to a sixth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit controls the second switch to switch from the second load resistor to the third load resistor when the output voltage of the second amplifier is lower than a second threshold value.

[0016] According to a seventh aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein in the first mode, the control unit determines the position of a finger pressing the sensor unit based on a plurality of detection signals of the plurality of sensor elements.

[0017] According to an eighth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit determines a click operation based on the plurality of detection signals, and determines the position of the finger when the click operation is input.

[0018] According to a ninth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit integrates the plurality of detection signals and determines the pressure applied to the sensor unit based on the integrated signal.

[0019] According to a tenth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein in the first mode, the control unit determines the positions of multiple fingers pressing the sensor unit based on multiple detection signals of the multiple sensor elements, and determines the balance of pressure of the multiple fingers.

[0020] According to an eleventh aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit integrates the plurality of detection signals and determines the pressure applied to the sensor unit based on the integrated signal.

[0021] According to a twelfth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit determines a click operation based on multiple detection signals from the multiple sensor elements, and switches from the first mode to the second mode when the click operation is input.

[0022] According to a thirteenth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit switches from the first mode to the second mode after a certain time has elapsed since the click operation was input.

[0023] According to a fourteenth aspect of the present invention, there is provided a sensor device according to any of the above aspects, further comprising an A / D converter connected to the output of the amplifier circuit, the A / D converter sampling the detection signal at each sampling period, and the sampling period in the second mode being set shorter than the sampling period in the first mode.

[0024] According to a fifteenth aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein the control unit determines a period of a pulse wave trough in the second mode and executes the first mode during that period.

[0025] According to a sixteenth aspect of the present invention, there is provided a sensor device according to any of the above aspects, further comprising a flexible support member and an air bag provided at the bottom of the support member, wherein the sensor unit is provided at the top of the support member and is configured to detect pressure applied to the air bag.

[0026] According to a seventeenth aspect of the present invention, there is provided the sensor device according to any one of the above aspects, wherein each of the plurality of sensor elements is a piezoelectric element.

[0027] According to an 18th aspect of the present invention, there is provided a sensor device according to any of the above aspects, wherein each of the plurality of sensor elements is constructed using a flexible organic piezoelectric layer.

[0028] According to the present disclosure, it is possible to provide a sensor device capable of improving the dynamic range.

[0029] FIG. 1 is a block diagram of a sensor device according to a first embodiment of the present invention. FIG. 2 is a circuit diagram of a sensor unit, a switch circuit, and an amplifier circuit shown in FIG. 1. FIG. 3 is a circuit diagram of a circuit portion connected to one sensor element. FIG. 4 is a circuit diagram showing an example of one amplifier included in an amplifier circuit. FIG. 5 is a flowchart illustrating the operation of the sensor device. FIG. 6 is a diagram illustrating the operation of the switch circuit in a divided drive mode. FIG. 7 is a diagram illustrating the operation of the switch circuit in a connected drive mode. FIG. 8 is a diagram illustrating measurement results in an example. FIG. 9 is a diagram illustrating an example of measurement results in a divided drive mode using a load resistance of 10 MΩ. FIG. 10 is a diagram illustrating an example of measurement results in a connected drive mode using a load resistance of 10 MΩ. FIG. 11 is a diagram illustrating an example of measurement results in a connected drive mode using a load resistance of 20 MΩ. FIG. 12 is a diagram illustrating an example of measurement results in a connected drive mode using a load resistance of 100 MΩ. FIG. 13 is a block diagram of the main parts of a sensor unit and a signal processing unit according to a second embodiment of the present invention. FIG. 14 is a circuit diagram of the main parts of a sensor unit and a signal processing unit according to a third embodiment of the present invention. FIG. 15 is a flowchart illustrating the operation of the sensor device. FIG. 16 is a diagram illustrating an example of the output voltage of the amplifier. FIG. 17 is a block diagram of a measurement device according to a fourth embodiment of the present invention. FIG. 18 is a schematic diagram illustrating the appearance of the measurement device. FIG. 19 is a schematic diagram illustrating the appearance of the measurement device during pulse wave measurement. FIG. 20 is a flowchart illustrating the operation of the measurement device. FIG. 21 is a diagram illustrating an example of a detection signal during a click operation. FIG. 22 is a diagram illustrating an example of pressure in the pressure measurement mode. FIG. 23 is a diagram illustrating an example of a detection signal in the pressure measurement mode. FIG. 24 is a diagram illustrating the operation of switching from the pressure measurement mode to the pulse wave measurement mode. FIG. 25 is a diagram illustrating an example of a detection signal in the pulse wave measurement mode. FIG. 26 is a block diagram illustrating the operation of an A / D converter according to a fifth embodiment of the present invention. FIG. 27 is a diagram illustrating the operation of the A / D converter. FIG. 28 is a flowchart illustrating the operation of a measurement device according to a sixth embodiment of the present invention. FIG. 29 is a diagram illustrating the operation of determining the period of the pressure measurement mode.Fig. 30 is a plan view of a measurement apparatus according to a seventh embodiment of the present invention, and Fig. 31 is a block diagram of a measurement system according to an eighth embodiment of the present invention.

[0030] Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and proportions of each drawing are not necessarily the same as those of the actual drawing. Furthermore, even when the same parts are shown in different drawings, the dimensional relationships and proportions may be different. In particular, the following embodiments are illustrative of devices and methods for embodying the technical concept of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical concept of the present invention. In the following description, elements having the same function and configuration are designated by the same reference numerals, and redundant description will be omitted.

[0031] In the following embodiment, a piezoelectric sensor will be described as an example of the sensor device 1.

[0032] [1] First Embodiment [1-1] Configuration of Sensor Device 1 Fig. 1 is a block diagram of a sensor device 1 according to a first embodiment of the present invention. The sensor device 1 includes a sensor unit 2, a signal processing unit 3, a controller 7, and a voltage generating circuit 12.

[0033] The sensor unit 2 includes a plurality of sensor elements. Each of the plurality of sensor elements is formed, for example, by a piezoelectric element. A piezoelectric element is a sensor element that utilizes the piezoelectric effect and is capable of outputting an electrical signal in response to pressure applied to a piezoelectric body. The sensor unit 2 outputs a plurality of detection signals corresponding to the plurality of sensor elements.

[0034] The signal processing unit 3 receives a plurality of detection signals from the sensor unit 2 and performs signal processing on the plurality of detection signals. The signal processing unit 3 includes a switch circuit 4, an amplifier circuit 5, a filter circuit 6, and the like.

[0035] The switch circuit 4 switches the signal path depending on two drive modes, which will be described later. The switch circuit 4 is configured by, for example, an analog switch circuit.

[0036] The amplifier circuit 5 receives the plurality of detection signals from the switch circuit 4. The amplifier circuit 5 amplifies the electrical signals input thereto.

[0037] The filter circuit 6 receives the plurality of detection signals from the amplifier circuit 5. The filter circuit 6 removes signals and noise in frequency bands other than the required frequency band. The filter circuit 6 includes a low-pass filter circuit.

[0038] The controller 7 comprehensively controls the operation of the sensor device 1. The controller 7 includes one or more processors such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor included in the controller 7 executes programs stored in a storage unit 9 to realize various functions. The controller 7 includes a mode control unit 8, a storage unit 9, an external interface 10, and a power supply control unit 11.

[0039] The mode control unit 8 controls multiple drive modes. The sensor device 1 can execute a divided drive mode and a connected drive mode. The divided drive mode is also referred to as a first mode. The connected drive mode is also referred to as a second mode. The divided drive mode is a mode in which sensing is performed using multiple sensor elements individually. The divided drive mode is a drive mode used when the voltage amplitude of the detection signal detected by the sensor unit 2 is relatively large. The divided drive mode can be used for motion sensors that use muscle movement, etc. The connected drive mode is a mode in which sensing is performed by connecting multiple sensor elements in parallel. The connected drive mode is a drive mode used when the voltage amplitude of the detection signal detected by the sensor unit 2 is relatively small. The connected drive mode can be used for pulse wave sensors that detect pulse, etc.

[0040] The storage unit 9 stores various data necessary for the operation of the sensor device 1 and functions as a working area for the processor included in the controller 7. The storage unit 9 includes a volatile memory and a non-volatile memory. The volatile memory includes a random access memory (RAM) and a register, etc. The non-volatile memory includes a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), etc.

[0041] The external interface 10 is connected to an external device via a wired or wireless connection and has a function of communicating with the external device. The external interface 10 executes interface processing based on a predetermined standard between the external device and the external device.

[0042] The power supply control unit 11 controls the operation of the voltage generation circuit 12. The voltage generation circuit 12 generates a plurality of voltages required for the operation of the sensor device 1. The voltage generation circuit 12 supplies voltages to the corresponding circuits.

[0043] FIG. 2 is a circuit diagram of the sensor unit 2, the switch circuit 4, and the amplifier circuit 5 shown in FIG.

[0044] The sensor unit 2 includes a plurality of sensor elements 20-1 to 20-n, where "n" is a natural number equal to or greater than 2. In this embodiment, common explanations for reference symbols with sub-numbers will use reference symbols with the sub-numbers omitted. As described above, the sensor element 20 is composed of a piezoelectric element. The plurality of sensor elements 20 are configured on the same substrate, for example. The piezoelectric element is configured to include a lower electrode, an upper electrode, and a piezoelectric layer sandwiched between them.

[0045] The switch circuit 4 includes a plurality of switches 21-1 to 21-n. The switches 21-1 to 21-n are connected to the plurality of sensor elements 20-1 to 20-n, respectively. The switches 21 are configured as single-pole double-throw (SPDT) switches that can switch between two paths (one pole and two contacts).

[0046] 3 is a circuit diagram illustrating an extracted circuit portion connected to one sensor element 20 (sensor element 20-1). The switch 21 has one input terminal T1 and two output terminals T2 and T3. The switch 21 switches between a first path connecting the input terminal T1 and the output terminal T2 and a second path connecting the input terminal T1 and the output terminal T3. The input terminal T1 of the switch 21 is connected to the output of the sensor element 20. A control signal CNT1 is input to the switch 21 from the controller 7. The switch 21 switches between the two paths based on the control signal CNT1.

[0047] The amplifier circuit 5 includes a plurality of amplifiers 22-1 to 22-n and a plurality of load resistors 23-1 to 23-n. The amplifier 22 is configured as an operational amplifier. The inputs of the plurality of amplifiers 22-1 to 22-n are connected to the output terminals T3 of the plurality of switches 21-1 to 21-n, respectively. The plurality of load resistors 23-1 to 23-n are connected to the inputs of the plurality of amplifiers 22-1 to 22-n, respectively. The plurality of amplifiers 22-1 to 22-n and the plurality of load resistors 23-1 to 23-n are used in a divided drive mode.

[0048] The amplifier circuit 5 further includes an amplifier 24 and a load resistor 25. The amplifier 24 is configured as an operational amplifier. An input of the amplifier 24 is commonly connected to the output terminals T2 of the multiple switches 21-1 to 21-n. The load resistor 25 is connected to the input of the amplifier 24. The amplifier 24 and the load resistor 25 are used in the coupled drive mode. The resistance value of the load resistor 25 is set to be larger than the resistance value of the load resistor 23.

[0049] Fig. 4 is a circuit diagram showing an example of one amplifier 22 included in the amplifier circuit 5. The configuration of the amplifier 24 is also the same as that shown in Fig. 4. The amplifier 22 is configured as, for example, a non-inverting amplifier.

[0050] The amplifier circuit 5 includes an amplifier 22, a load resistor 23, an input terminal 30, an output terminal 31, and resistors 32 and 33. The input terminal 30 is connected to the output terminal T3 of the switch 21. The output terminal 31 is connected to the filter circuit 6.

[0051] A positive power supply V+ (for example, 5 V) is supplied to the positive power supply terminal of the amplifier 22. A negative power supply V− (for example, −5 V) is supplied to the negative power supply terminal of the amplifier 22.

[0052] The non-inverting input terminal (+) of the amplifier 22 is connected to the input terminal 30. One end of the load resistor 23 is connected to the non-inverting input terminal of the amplifier 22, and the other end is connected to the ground terminal GND. 0 V is supplied to the ground terminal GND.

[0053] The inverting input terminal (-) of amplifier 22 is connected to one end of resistor 32. The other end of resistor 32 is connected to ground terminal GND. One end of resistor 33 is connected to the output of amplifier 22, and the other end is connected to the inverting input terminal of amplifier 22. The output of amplifier 22 is connected to output terminal 31.

[0054] The load resistor 23 converts the charge supplied from the sensor element 20 into a voltage. The amplifier 22 is capable of amplifying and outputting the input signal. The amplification factor of the amplifier 22 is calculated by the following formula (1). Assume that the input voltage of the amplifier 22 is Vi, the output voltage of the amplifier 22 is Vo, the resistance value of the resistor 32 is R1, and the resistance value of the resistor 33 is R2. Vo=(1+(R2 / R1))Vi (1)

[0055] [1-2] Operation Next, a description will be given of the operation of the sensor device 1 configured as described above. FIG.

[0056] The plurality of sensor elements 20 included in the sensor unit 2 detect pressure. That is, the plurality of sensor elements 20 included in the sensor unit 2 detect pressure and output a detection signal as the detection result.

[0057] The signal processing unit 3 receives a plurality of detection signals from a plurality of sensor elements 20 included in the sensor unit 2 (step S100).

[0058] Next, the mode control unit 8 selects a drive mode (step S101). The drive mode determination operation is performed in step S107, which will be described later. As an initial operation, for example, the mode control unit 8 may select a predetermined drive mode. Information on the predetermined drive mode is stored in the storage unit 9.

[0059] If the division drive mode is selected in step S101, the mode control unit 8 switches the switch circuit 4 to the path of the division drive mode (step S102). That is, the mode control unit 8 transmits a control signal CNT1 to the switch circuit 4 to switch to the path of the division drive mode.

[0060] 6 is a diagram illustrating the operation of the switch circuit 4 in the division drive mode, in which five sensor elements 20 are shown as an example.

[0061] The switches 21 respectively connect the sensor elements 20 to the amplifiers 22. In the divided drive mode, the amplifier 24 is not connected to the sensor elements 20.

[0062] Next, the signal processing unit 3 amplifies and filters the detection signals (step S104). That is, in the divided drive mode, the amplifier circuit 5 amplifies the detection signals of the sensor elements 20, and the filter circuit 6 filters the detection signals.

[0063] Subsequently, the mode control unit 8 outputs the plurality of detection signals transmitted from the signal processing unit 3 to an external device via the external interface 10 (step S105).

[0064] On the other hand, if the connected drive mode is selected in step S101, the mode control unit 8 switches the switch circuit 4 to the path of the connected drive mode (step S103). That is, the mode control unit 8 transmits a control signal CNT1 to the switch circuit 4 to switch to the path of the connected drive mode.

[0065] 7 is a diagram illustrating the operation of the switch circuit 4 in the connected drive mode, in which five sensor elements 20 are shown as an example.

[0066] Each of the switches 21 commonly connects the sensor elements 20 to the amplifier 24. That is, the sensor elements 20 are connected in parallel, and the charges of the sensor elements 20 are added together and supplied to the amplifier 24. This increases the voltage amplitude and dynamic range of the detection signal. In the coupled drive mode, the amplifiers 22 are not connected to the sensor elements 20. The mode control unit 8 may control the switch circuit 4 to commonly connect two or more sensor elements 20 to the amplifier 24 in the coupled drive mode.

[0067] Next, the signal processing unit 3 amplifies and filters the detection signal (step S104). That is, in the coupled drive mode, the amplifier circuit 5 amplifies one detection signal obtained by adding up the charges of the multiple sensor elements 20, and the filter circuit 6 filters the one detection signal.

[0068] Subsequently, the mode control unit 8 outputs the detection signal transmitted from the signal processing unit 3 to an external device via the external interface 10 (step S105).

[0069] Next, the mode control unit 8 determines the voltage amplitude of the detection signal (step S106). If the current mode is the divided drive mode, the voltage amplitude may be determined for any one of the multiple detection signals, or the voltage amplitude may be determined for each of the multiple detection signals. The mode control unit 8 compares the determined voltage amplitude with a threshold value and determines whether the determined voltage amplitude is greater than the threshold value. A voltage amplitude equal to or less than the threshold value indicates a small dynamic range. A voltage amplitude greater than the threshold value indicates a large dynamic range.

[0070] Next, the mode control unit 8 determines whether to switch the drive mode based on the result of the voltage amplitude determination (step S107). That is, if the determined voltage amplitude is greater than a threshold, the mode control unit 8 selects the divided drive mode. If the determined voltage amplitude is equal to or less than the threshold, the mode control unit 8 selects the connected drive mode.

[0071] The mode control unit 8 may select a drive mode requested by an external device via the external interface 10. The mode control unit 8 may select a drive mode based on a button operation by the user, a wrist gesture input by the user, or a signal indicating that an external force has been applied to the artery at the measurement location.

[0072] [1-3] Examples Next, specific examples will be described. The experimental conditions for the examples are as follows: Detected object: In the divided drive mode, the detected object is wrist motion. In the connected drive mode, the detected object is wrist pulse. Sensor unit: 12 sensor elements corresponding to 12 channels (CH) were used. Fixation method: The sensor unit was fixed to the wrist using elastomer. Pressure was applied to the wrist to make the pulse easier to detect. In this case, three fingers were lightly placed over the artery in the wrist, as in pulse diagnosis. Other methods include placing the wrist on a mouse pad, wrapping a wristband over the elastomer, or applying air pressure to the wrist like a blood pressure monitor. Signal processing unit: Load resistances of 10 MΩ, 20 MΩ, and 100 MΩ were used to convert charge to voltage. The signal was amplified 11 times using an amplifier. Mode control unit: An external switch was used to switch the drive mode. Result measurement: The voltage waveform was observed using an oscilloscope.

[0073] Fig. 8 is a diagram illustrating the measurement results in the example. Fig. 8 shows the detection target, drive mode, load resistance (Ω), amplifier gain, and voltage amplitude (V). The voltage amplitude is the voltage amplitude of the detection signal output from the signal processing unit.

[0074] In motion detection in the divided drive mode, the voltage amplitude varies from 1 V to 5 V depending on the motion. Motion can be detected according to the voltage of 12 channels.

[0075] When detecting a pulse in the divided drive mode, the voltage amplitude is as small as 0.6 V. Therefore, it is desirable to detect minute signals such as a pulse in the connected drive mode. Detecting a pulse in the connected drive mode more than doubles the voltage amplitude compared to the divided drive mode. This allows the detection signal to be identified with a voltage amplitude similar to that of motion detection, thereby increasing the dynamic range.

[0076] Furthermore, when detecting the pulse in the divided drive mode, it is necessary to check in advance which channel of the sensor unit is detecting the pulse. In contrast, in the connected drive mode, there is no need to align the pulse measurement point with the position of the channel of the sensor unit. Therefore, the pulse can be easily measured using the connected drive mode.

[0077] FIG. 9 shows an example of measurement results in the divided drive mode using a load resistance of 10 MΩ. FIG. 9 shows the voltage waveform of a channel from which a pulse wave could be detected among the 12 channels. FIG. 10 shows an example of measurement results in the connected drive mode using a load resistance of 10 MΩ. FIG. 11 shows an example of measurement results in the connected drive mode using a load resistance of 20 MΩ. FIG. 12 shows an example of measurement results in the connected drive mode using a load resistance of 100 MΩ. In FIGS. 9 to 12, the horizontal axis represents time (arbitrary units) and the vertical axis represents voltage (V). In FIGS. 9 to 12, 50 points of raw data are averaged and displayed to remove the effects of power supply noise. Waveforms corresponding to five pulse beats are shown in FIGS. 9 to 12.

[0078] As can be seen from Fig. 9, in the divided driving mode, the voltage amplitude is small, making it difficult to distinguish between the pulse and noise. As can be seen from Fig. 10, by switching to the connected driving mode, the voltage amplitude can be increased, making it possible to measure the pulse easily and accurately.

[0079] 11 and 12, the voltage amplitude in the coupled drive mode can be increased by increasing the load resistance. The load resistance can be set appropriately depending on the specifications of the sensor device 1.

[0080] [1-4] Effects of the First Embodiment According to the first embodiment, the sensor device 1 can execute a divided drive mode in which the plurality of sensor elements 20 are divided and driven, and a connected drive mode in which the plurality of sensor elements 20 are connected and driven. In the divided drive mode, the sensor device 1 can output a plurality of detection signals from the plurality of sensor elements 20. In the connected drive mode, the sensor device 1 can output a single detection signal that combines the signals from the plurality of sensor elements 20.

[0081] In addition, when the voltage amplitude of the detection signal is relatively large, the division driving mode can be selected, and when the voltage amplitude of the detection signal is relatively small, the connection driving mode can be selected.

[0082] Furthermore, by executing the coupled drive mode, the voltage amplitude and dynamic range of the detection signal can be increased, which allows for more accurate pressure detection. As a result, the dynamic range of the sensor device 1 can be improved in both the divided drive mode and the coupled drive mode.

[0083] In the divided drive mode, the sensor device 1 can detect pressure in each of the multiple regions where the multiple sensor elements 20 are respectively arranged. In the connected drive mode, the sensor device 1 can detect pressure in the entire region of the multiple sensor elements 20, treating the multiple sensor elements 20 as a single sensor.

[0084] Furthermore, for example, when detecting a pulse from an artery in the wrist, the artery may be thin and the detectable range may be narrow. Even in this case, the pulse can be detected from the target artery by changing the detection area of ​​the sensor unit 2.

[0085] Furthermore, when the voltage amplitude of the detection signal is relatively large, the sensor device 1 can be used as a motion sensor.

[0086] [2] Second Embodiment In the second embodiment, the sensor unit 2 has a plurality of blocks 40, and the divided drive mode and the coupled drive mode are switched in units of blocks 40.

[0087] 13 is a block diagram of the main parts of a sensor unit 2 and a signal processing unit 3 according to the second embodiment of the present invention. The sensor device 1 includes a sensor unit 2, a plurality of switch circuits 4, and a plurality of amplifier circuits 5.

[0088] The sensor unit 2 includes a plurality of blocks 40. In this embodiment, four blocks 40-1 to 40-4 are shown as an example. Each block 40 includes a plurality of sensor elements 20. In this embodiment, a configuration in which one block 40 includes three sensor elements 20 is shown as an example. The number of blocks 40 and the number of sensor elements 20 can be set arbitrarily. The arrangement of the sensor elements 20 can also be set arbitrarily. The number of sensor elements 20 included in each of the plurality of blocks 40 may be the same or different.

[0089] A plurality of switch circuits 4 are connected to each of the plurality of blocks 40. In this embodiment, four switch circuits 4-1 to 4-4 are shown as an example. In Fig. 13, wiring between the plurality of blocks 40 and the plurality of switch circuits 4 is omitted. The configuration of each switch circuit 4 is the same as in the first embodiment.

[0090] A plurality of amplifier circuits 5 are connected to the plurality of switch circuits 4, respectively. In this embodiment, four amplifier circuits 5-1 to 5-4 are shown as an example. The configuration of each amplifier circuit 5 is the same as that in the first embodiment.

[0091] The operation of each block 40 is the same as that of the first embodiment. The mode control unit 8 executes the process of FIG.

[0092] According to the second embodiment, it is possible to switch between the divided drive mode and the connected drive mode in units of blocks 40. This allows the sensor device 1 to be optimally configured depending on the part of the body to be measured.

[0093] [3] Third Embodiment In the third embodiment, a plurality of load resistors 25 are provided to be connected to the amplifier 24 for the connected drive mode, and one of the plurality of load resistors 25 is selected for use.

[0094] 14 is a circuit diagram of the main parts of the sensor unit 2 and the signal processing unit 3 according to the third embodiment of the present invention. The configurations of the switches and amplifiers for the divided drive mode are the same as those in the first embodiment.

[0095] The amplifier circuit 5 includes an amplifier 24 for the coupled drive mode, a switch 41, and a plurality of load resistors 25. The plurality of load resistors 25 have different resistance values. In this embodiment, three load resistors 25-1 to 25-3 are shown as an example. The number of load resistors 25 may be two, or may be four or more.

[0096] A switch 41 is connected to the input of the amplifier 24. The switch 41 is configured as a single-pole, triple-throw switch that can switch between three paths (one pole and three contacts).

[0097] An input terminal (pole) of the switch 41 is connected to the input of the amplifier 24. Three output terminals (three contacts) of the switch 41 are connected to one end of each of the load resistors 25-1 to 25-3. The other ends of the load resistors 25-1 to 25-3 are connected to the ground terminal GND.

[0098] A control signal CNT2 is input from the mode control unit 8 to a control terminal of the switch 41. The switch 41 switches between three paths based on the control signal CNT2. That is, the switch 41 switches which of the multiple load resistors 25 is connected to the amplifier 24 based on the control signal CNT2. For example, the load resistor 25-1 is 10 MΩ, the load resistor 25-2 is 50 MΩ, and the load resistor 25-3 is 100 MΩ.

[0099] The operation of the sensor device 1 configured as above will now be described. Fig. 15 is a flowchart illustrating the operation of the sensor device 1. The following operation is always performed in the coupled drive mode.

[0100] The mode control unit 8 acquires the output voltage of the amplifier 24 for the connected drive mode (step S200).

[0101] Next, the mode control unit 8 determines whether the output voltage of the amplifier 24 is lower than the lower threshold or higher than the upper threshold (step S201). The lower threshold and the upper threshold are threshold voltages for setting the output voltage of the amplifier 24 to an optimal range. The lower threshold and the upper threshold have a relationship of "lower threshold < upper threshold." The output voltage of the amplifier 24 is preferably in a range greater than or equal to the lower threshold and less than or equal to the upper threshold. The lower threshold and the upper threshold are set appropriately according to the specifications of the sensor device 1. For example, the upper threshold is preferably set to the lower of either 90% of the detectable range of the A / D converter or 90% of the output voltage range of the amplifier 24. The lower threshold is preferably set to the higher of either 10% of the detectable range of the A / D converter or 10% of the output voltage range of the amplifier 24. This makes it possible to set thresholds that maximize the effective range of the A / D converter while also taking into account constraints imposed by the amplifier's output range.

[0102] If the output voltage of the amplifier 24 is lower than the lower threshold or higher than the upper threshold (step S201 = Yes), the mode control unit 8 determines whether a certain time T has elapsed (step S202). By performing the process of step S202, it is possible to control the process so that voltage fluctuations due to noise or the like are not detected.

[0103] If a certain time T has elapsed (step S202 = Yes), the mode control unit 8 changes the load resistance (step S203). Specifically, if the output voltage of the amplifier 24 is lower than the lower threshold, the mode control unit 8 changes the load resistance so that the resistance value of the load resistance increases. The mode control unit 8 supplies a control signal CNT2 to the switch 41, and if the current load resistance is 10 MΩ, changes the load resistance to 50 MΩ, and if the current load resistance is 50 MΩ, changes the load resistance to 100 MΩ. By increasing the resistance value of the load resistor 25, the output voltage of the amplifier 24 can be increased.

[0104] Furthermore, when the output voltage of amplifier 24 is higher than the upper threshold, mode control unit 8 changes the load resistance so that the resistance value of the load resistance is lower. Mode control unit 8 supplies control signal CNT2 to switch 41, and when the current load resistance is 100 MΩ, changes the load resistance to 50 MΩ, and when the current load resistance is 50 MΩ, changes the load resistance to 10 MΩ. By reducing the resistance value of load resistor 25, the output voltage of amplifier 24 can be lowered.

[0105] Fig. 16 is a diagram illustrating an example of the output voltage of the amplifier 24. The horizontal axis of Fig. 16 represents time (arbitrary units), and the vertical axis represents the output voltage (arbitrary units) of the amplifier 24. Fig. 16 includes graphs of the voltage input to the amplifier 24 (input voltage), the voltage amplified by the amplifier 24 (amplified voltage), and the voltage output by the amplifier 24 (output voltage).

[0106] The maximum output voltage of the amplifier 24 is referred to as Vom. When the voltage calculated by "input voltage * amplification factor" exceeds the maximum output voltage Vom, the output voltage of the amplifier 24 peaks out and becomes a constant voltage.

[0107] When the load resistance 25 is 100 MΩ, the output voltage of the amplifier 24 is higher than an upper threshold (e.g., Vom). At this time, the mode control unit 8 determines that a certain time T has elapsed. Therefore, the mode control unit 8 changes the load resistance 25 to 50 MΩ. Furthermore, when the load resistance 25 is 50 MΩ, the output voltage of the amplifier 24 is higher than an upper threshold (e.g., Vom). At this time, the mode control unit 8 determines that a certain time T has elapsed. Therefore, the mode control unit 8 changes the load resistance 25 to 10 MΩ. In this way, the output voltage of the amplifier 24 is set to a range equal to or higher than the lower threshold and equal to or lower than the upper threshold.

[0108] As a modified example, the gain of the amplifier 24 may be changed according to the output voltage of the amplifier 24. The gain of the amplifier 24 can be adjusted by changing the resistance value R1 of the resistor 32 and / or the resistance value R2 of the resistor 33 in FIG. 4. Specifically, a plurality of resistors with different resistance values ​​are provided for one or both of the resistors 32 and 33, and the plurality of resistors are switched using a switch. The mode control unit 8 sets the gain to a high value when the output voltage of the amplifier 24 is lower than a lower threshold, and sets the gain to a low value when the output voltage of the amplifier 24 is higher than an upper threshold.

[0109] According to the third embodiment, it is possible to obtain optimum detection signals in both the division drive mode and the connection drive mode.

[0110] [4] Fourth Embodiment [4-1] Configuration of the Measuring Device 50 Fig. 17 is a block diagram of a measuring device 50 according to a fourth embodiment of the present invention. The measuring device 50 includes a sensor unit 2, a signal processing unit 3, a control unit 52, a storage unit 53, a communication unit 54, and a voltage generating circuit 12. The measuring device 50 is also called a sensor device.

[0111] The sensor unit 2 detects pressure applied to itself. The sensor unit 2 is capable of detecting pressure in each of a plurality of partial regions obtained by dividing the detection region (the region in which the sensor unit 2 is disposed). The sensor unit 2 outputs a plurality of detection signals corresponding to the plurality of partial regions, respectively. The detection signals output by the sensor unit 2 consist of electric charges.

[0112] The signal processing unit 3 receives a plurality of detection signals from the sensor unit 2 and performs signal processing on these detection signals. The signal processing unit 3 includes a switch circuit 4, an amplifier circuit 5, and an A / D converter 51. The circuit diagrams of the sensor unit 2, switch circuit 4, and amplifier circuit 5 shown in Fig. 17 are the same as those in Figs. 2 to 4.

[0113] The switch circuit 4 switches the signal path between the sensor unit 2 and the amplifier circuit 5 depending on the measurement mode. The switch circuit 4 is formed of, for example, an analog switch circuit.

[0114] The amplifier circuit 5 receives a plurality of detection signals from the sensor unit 2 via the switch circuit 4. The amplifier circuit 5 amplifies the voltage signals input thereto.

[0115] The A / D converter 51 receives a plurality of detection signals from the amplifier circuit 5. The A / D converter 51 converts the analog signals output from the amplifier circuit 5 into digital signals. The detection signals (digital signals) output from the A / D converter 51 are sent to the control unit 52.

[0116] The control unit 52 comprehensively controls the operation of the measuring device 50. The control unit 52 includes one or more processors such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor included in the control unit 52 executes programs stored in the storage unit 53 to realize various functions.

[0117] The control unit 52 controls a plurality of measurement modes. The control unit 52 can execute a pressure measurement mode and a pulse wave measurement mode. The pressure measurement mode is also referred to as a first mode. The pulse wave measurement mode is also referred to as a second mode. The pressure measurement mode is a mode in which the pressure state (including the position of the finger) is measured when the examiner (or user) applies pressure to the sensor unit 2 with their finger. The pulse wave measurement mode is a mode in which the actual pulse wave is measured when the conditions for measuring the pulse wave are met. The pulse wave is a measurement of the change in arterial pressure or volume caused by the beating of the heart.

[0118] In the pressure measurement mode, the sensor unit 2 is driven in a divided manner. The divided manner is a mode in which a plurality of detection signals from a plurality of sensor elements 20 are output respectively. In the pulse wave measurement mode, the sensor unit 2 is driven in a connected manner. The connected manner is a mode in which a plurality of outputs from a plurality of sensor elements 20 are connected to output a single detection signal.

[0119] The storage unit 53 stores various data necessary for the operation of the measuring device 50 and functions as a working area for the processor included in the control unit 52. The storage unit 53 includes a volatile memory and a non-volatile memory. The volatile memory includes a random access memory (RAM) and a register, etc. The non-volatile memory includes a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), etc.

[0120] The communication unit 54 is connected to an external device via a wired or wireless connection and has the function of communicating with the external device. The communication unit 54 executes interface processing based on a predetermined standard with the external device. The communication unit 54 includes a wired interface circuit for wired communication or a wireless interface circuit for wireless communication.

[0121] The voltage generating circuit 12 generates a plurality of voltages required for the operation of the measuring device 50. The voltage generating circuit 12 supplies voltages to the corresponding circuits.

[0122] The measuring device 50 is used, for example, to measure the pulse wave of a user. The measuring device 50 is used by being worn, for example, on the user's wrist. Fig. 18 is a schematic diagram illustrating the external appearance of the measuring device 50. Fig. 18 is a schematic diagram as viewed from the palm side of the user's hand.

[0123] The pulse wave is measured by touching the pulsation of the radial artery. The sensor unit 2 is attached to the radial artery near the wrist. The sensor unit 2 is configured to be flexible. The sensor unit 2 includes a flexible substrate 2A. A plurality of sensor elements 20 are provided on the substrate 2A. The sensor elements 20 are configured using a flexible organic piezoelectric layer. The sensor unit 2 can be attached to a curved part of the user's body, such as the wrist.

[0124] The measuring device 50 includes a housing 55. The housing 55 houses circuits other than the sensor unit 2. The sensor unit 2 is connected to the housing 55.

[0125] FIG. 19 is a schematic diagram illustrating the appearance of the measurement device 50 during pulse wave measurement. When measuring a pulse wave, the sensor unit 2 is pressed with three fingers (index, middle, and ring fingers) of the examiner (or user). In traditional Chinese medicine, when the middle finger is placed next to the radial styloid process, the areas pressed by the three fingers are called, starting from the index finger, cunkou, guanshang, and shakuzhong. Applying pressure to the sensor unit 2 brings it into close contact with the measurement area, enabling more accurate pulse wave measurement.

[0126] [4-2] Operation Next, a description will be given of the operation of the measuring device 50 configured as described above. FIG.

[0127] The control unit 52 executes the pressure measurement mode as an initial state (step S300). In the pressure measurement mode, the control unit 52 drives the sensor unit 2 in a divided manner.

[0128] The operation of the switch circuit 4 in the pressure measurement mode is the same as that shown in FIG. 6 . The control unit 52 sends a control signal CNT1 to the switch circuit 4 to switch to the path of the pressure measurement mode. The multiple switches 21 each connect the multiple sensor elements 20 to the multiple amplifiers 22. In the pressure measurement mode, the multiple sensor elements 20 are not connected to the amplifier 24. In the pressure measurement mode, the multiple amplifiers 22 each output the multiple outputs of the multiple sensor elements 20 as multiple detection signals. The multiple detection signals output from the amplifier circuit 5 are converted into digital signals by the A / D converter 51 and sent to the control unit 52.

[0129] Next, the control unit 52 monitors whether a start operation has been input (step S301). The start operation is an operation that instructs acquisition of pressing information, and the instruction can be given based on an action such as clicking or button input. In this embodiment, the start operation is an operation of clicking the sensor unit 2 (referred to as a click operation) or an operation of double-clicking the sensor unit 2. By configuring the control unit 52 to determine whether a double-click has occurred, erroneous detection can be suppressed.

[0130] FIG. 21 is a diagram illustrating an example of a detection signal during a click operation. The horizontal axis of FIG. 21 represents time, and the vertical axis represents the detection signal (voltage value). The detection signal is in arbitrary units. FIG. 21 shows extracted detection signals from three sensor elements 20 corresponding to three fingers of an examiner (or user) pressing against the sensor unit 2. In FIG. 21, the positions of the three sensors are shifted up and down so that the waveforms can be easily understood.

[0131] When the examiner (or user) clicks the sensor unit 2 with his / her finger, a large pressure is applied to the sensor unit 2. The control unit 52 compares the detection signal (voltage signal) with a predetermined threshold (voltage value), and when it determines that the voltage level of the detection signal is equal to or greater than the threshold, it determines that a click operation has been input by the examiner (or user).

[0132] The number of fingers determined in step S301 may be one or more. Pulse diagnosis may be performed using three fingers (index finger, middle finger, and ring finger). If the control unit 52 determines that a click operation has been input using three fingers, the control unit 52 may proceed to the next step.

[0133] If a start operation is input (step S301 = Yes), the control unit 52 acquires pressure information measured in the pressure measurement mode (step S302). Subsequently, the control unit 52 determines the state of the finger pressing the sensor unit 2 based on the pressure information (step S303). Specifically, the control unit 52 determines the position of the finger pressing the sensor unit 2. The control unit 52 stores information related to the determined state of the finger in the storage unit 53.

[0134] Fig. 22 is a diagram illustrating an example of pressure in the pressure measurement mode. Fig. 22(a) is a diagram illustrating the state of the examiner's (or user's) finger. Fig. 22(b) is a diagram illustrating the pressure applied to the sensor unit 2. The horizontal axis of Fig. 22(b) represents the position corresponding to Fig. 22(a), and the vertical axis represents the pressure. The pressure is expressed in arbitrary units.

[0135] Assume that the examiner (or user) presses the surface of the sensor unit 2 (the position of the sensor unit surface in FIG. 22) with three fingers: the index finger, the middle finger, and the ring finger. The pressure applied by the fingers varies depending on the positions of the fingers. The change in pressure can be detected by evaluating the detection signals of the multiple sensor elements 20.

[0136] FIG. 23 is a diagram illustrating an example of a detection signal in the pressure measurement mode. FIG. 23(a) is a diagram illustrating the state of the examiner's (or user's) finger. The left side of FIG. 23(a) is the elbow side, and the right side is the wrist side. FIG. 23(b) is a diagram illustrating a schematic of a detection signal. The detection signal is in arbitrary units. The horizontal axis of FIG. 23(b) represents the position corresponding to FIG. 23(a), and the vertical axis represents the detection signal (voltage value). It is assumed that the sensor unit 2 is worn on the user's arm (near the wrist). The multiple squares of the sensor unit 2 schematically represent sensor elements 20.

[0137] The control unit 52 receives a plurality of detection signals from the plurality of sensor elements 20, respectively. A plurality of dots in FIG. 23(b) indicate a plurality of detection signals corresponding to the plurality of sensor elements 20. The control unit 52 determines the position of the examiner's (or user's) fingers by determining the peak distribution of the plurality of detection signals. In FIG. 23(b), three peaks are determined by determining the plurality of detection signals. The control unit 52 determines the positions of the three peaks as the positions of three fingers (e.g., index finger, middle finger, and ring finger).

[0138] When determining the state of the finger in step S303, the control unit 52 integrates each of the plurality of detection signals, which are voltage signals. By integrating the detection signals, the magnitude of the pressure can be determined more accurately.

[0139] It is also possible to omit step S301 and determine the state of the finger pressing the sensor unit 2 during the pressure measurement mode.

[0140] Thereafter, an operation of switching from the pressure measurement mode to the pulse wave measurement mode is performed. FIG. 24 is a diagram illustrating the operation of switching from the pressure measurement mode to the pulse wave measurement mode. The horizontal axis of FIG. 24 represents time, and the vertical axis represents the detection signal (voltage value). The detection signal is in arbitrary units. In the pressure measurement mode of FIG. 24, the detection signals of three sensor elements 20 corresponding to three fingers are extracted and shown. In the pressure measurement mode of FIG. 24, the waveforms are illustrated shifted vertically so that they can be easily understood.

[0141] The control unit 52 monitors whether a switching operation has been input (step S304). A switching operation is an operation to instruct switching from the pressure measurement mode to the pulse wave measurement mode. In this embodiment, the switching operation is an operation of clicking the sensor unit 2 or an operation of double-clicking the sensor unit 2. By configuring the control unit 52 to determine whether a double-click has occurred, erroneous detection can be suppressed. The control unit 52 compares the detection signal (voltage signal) with a predetermined threshold (voltage value), and if it determines that the voltage level of the detection signal is equal to or greater than the threshold, it determines that a click operation has been input by the examiner (or user).

[0142] The number of fingers used in step S304 may be one or more. Pulse diagnosis may be performed using three fingers (index finger, middle finger, and ring finger). By using three fingers to take the pulse, the pulse rate and rhythm can be determined more accurately. The control unit 52 may proceed to the next step when it determines that a click operation has been input using three fingers.

[0143] If a switching operation is input (step S304 = Yes), the control unit 52 determines the balance of pressure applied by the multiple fingers (referred to as pressure balance) based on the multiple detection signals (step S305). When the index finger, middle finger, and ring finger are pressing against the sensor unit 2, the control unit 52 determines the magnitude of the pressure and determines which of the index finger, middle finger, and ring finger is applying the most pressure, the finger applying the intermediate pressure, and the finger applying the least pressure. By obtaining information about the pressure balance, it is possible to determine or estimate which finger the examiner (or user) is using to press the sensor unit 2 most strongly and which finger is using to measure the pulse wave. The pressure balance information is stored in the storage unit 53.

[0144] When determining the pressure balance in step S305, the control unit 52 integrates each of the multiple detection signals, which are voltage signals. By integrating the detection signals, the magnitude of the pressure can be determined more accurately. Figure 24 shows the detection signals integrated from the timing at which pressure starts.

[0145] Next, the control unit 52 monitors whether a certain time T has elapsed since the switching operation was input (step S306). The certain time T is set to ensure time for the finger pressure to stabilize. After the certain time T has elapsed (step S306 = Yes), the control unit 52 executes the pulse wave measurement mode (step S307).

[0146] The operation of the switch circuit 4 in the pulse wave measurement mode is the same as that shown in FIG. 7 . The control unit 52 drives the sensor unit 2 in the pulse wave measurement mode. The control unit 52 transmits a control signal CNT1 to the switch circuit 4 to switch to the path for the pulse wave measurement mode. Each of the switches 21 commonly connects the sensor elements 20 to the amplifier 24. That is, the sensor elements 20 are connected in parallel, and the charges of the sensor elements 20 are added together and supplied to the amplifier 24. This increases the voltage amplitude and dynamic range of the detection signal. In the pulse wave measurement mode, the sensor elements 20 are not connected to the amplifiers 22. The detection signal output from the amplifier circuit 5 is converted into a digital signal by the A / D converter 51 and transmitted to the control unit 52. The control unit 52 may control the switch circuit 4 to commonly connect two or more sensor elements 20 to the amplifier 24 in the pulse wave measurement mode.

[0147] The pressure applied to the sensor unit 2 by the pulse at the wrist is small. In this embodiment, in the pulse wave measurement mode, the charges of the multiple sensor elements 20 are added together, so that the pressure can be detected as a large voltage value.

[0148] 25 is a diagram illustrating an example of a detection signal in the pulse wave measurement mode. The horizontal axis of Fig. 25 represents time, and the vertical axis represents the detection signal (voltage value). The detection signal is expressed in arbitrary units.

[0149] In the pulse wave measurement mode, the charges of all the sensor elements 20 are added together, and the added charges are output as a detection signal from the amplifier 24. As can be seen from Fig. 25, the dynamic range in the pulse wave measurement mode can be widened. The control unit 52 can measure the pulse wave based on the detection signal with a wide dynamic range.

[0150] Next, the control unit 52 acquires information measured in the pulse wave measurement mode (referred to as pulse wave information) (step S308). The control unit 52 stores the pulse wave information measured in the pulse wave measurement mode in the storage unit 53.

[0151] Next, the control unit 52 monitors whether a switching operation has been input (step S309). The switching operation is an operation of clicking or double-clicking the sensor unit 2. If a switching operation has been input (step S309 = Yes), the control unit 52 proceeds to step S300 and repeats the pressure measurement mode.

[0152] [4-3] Effects of the Fourth Embodiment According to the fourth embodiment, the measurement device 50 can execute a series of measurement modes consisting of a pressure measurement mode and a pulse wave measurement mode. In the pressure measurement mode, the state of the finger pressing against the sensor unit 2 can be determined. In the pulse wave measurement mode, minute pressures can be measured over a wide dynamic range. This makes it possible to realize a measurement device 50 that can measure the information necessary for pulse diagnosis.

[0153] In addition, in the pressure measurement mode, the position of the finger that the examiner (or user) is pressing can be determined or estimated, which allows measurement to be performed in association with information about the finger pressing the wrist and the pulse wave.

[0154] Furthermore, the measurement results of the measuring device 50 can be used for pulse diagnosis. In pulse diagnosis, the state of illness can be diagnosed according to the position on the wrist where the pulse wave is measured (for example, the positions known as cunkou, guanshang, and shakuzhong). The measuring device 50 can measure the state of the fingers pressing on the cunkou, guanshang, and shakuzhong points, as well as the pulse wave at the pressing positions. This allows for accurate pulse diagnosis based on the data.

[0155] It is also possible to measure the pressure balance of multiple fingers pressing on the wrist. This allows the examiner (or user) to determine the finger that is pressing hard. Using this information in pulse diagnosis allows for more accurate diagnosis.

[0156] In the fourth embodiment, all of the sensor elements 20 of the sensor unit 2 are driven in conjunction with each other in the pulse wave measurement mode. As a modification, some (two or more) of all the sensor elements 20 may be driven in the pressure measurement mode without being driven in conjunction with each other, and pressure may be measured in parallel with pulse wave measurement.

[0157] [5] Fifth Embodiment In the fifth embodiment, the sampling period of the A / D converter 51 is changed depending on the measurement mode.

[0158] 26 is a block diagram illustrating the operation of an A / D converter 51 according to a fifth embodiment of the present invention. The outputs of three amplifiers 22 connected to any three sensor elements 20 out of the plurality of sensor elements 20 are denoted as channels CH_1 to CH_3. The output of the amplifier 24 in the pulse wave measurement mode is denoted as channel CH_A.

[0159] The A / D converter 51 samples the plurality of detection signals output from the amplifier circuit 5 at each sampling period and converts the sampled analog signals into digital signals. The output of the A / D converter 51 is sent to the control unit 52.

[0160] FIG. 27 is a diagram illustrating the operation of the A / D converter 51. The horizontal axis of FIG. 27 represents time, and the vertical axis represents the detection signal (voltage value). The detection signal is expressed in arbitrary units. FIG. 27 shows the voltage waveforms of channels CH_1 to CH_3 and CH_A in FIG. 26. In the pressure measurement mode of FIG. 27, the waveforms are shifted vertically so that they can be easily understood.

[0161] In the pressure measurement mode, the A / D converter 51 samples the channels CH_1 to CH_3 at the same sampling period. The dots added to the waveforms in Fig. 27 indicate the sampling period of the A / D converter 51 (ADC sampling in Fig. 27).

[0162] In the pulse wave measurement mode, the A / D converter 51 samples the channel CH_A at a predetermined sampling period. The sampling period of the A / D converter 51 in the pulse wave measurement mode is set to be shorter than the sampling period of the A / D converter 51 in the pressure measurement mode. The sampling period of the A / D converter 51 is controlled by the control unit 52.

[0163] The waveform shown by the dashed line in the pulse wave measurement mode in Figure 27 is the result of sampling in the pulse wave measurement mode at the same sampling period as the sampling period in the pressure measurement mode. If the sampling period is long, the dynamic range of the detection signal becomes small. By shortening the sampling period in the pulse wave measurement mode, the dynamic range of the detection signal can be increased.

[0164] [6] Sixth Embodiment In the sixth embodiment, the pulse wave measurement mode is switched to the pressure measurement mode at regular intervals to determine the pressure balance of the finger.

[0165] 28 is a flowchart illustrating the operation of the measurement device 50 according to the sixth embodiment of the present invention. The processing in FIG. 28 corresponds to the operation in the pulse wave measurement mode.

[0166] The control unit 52 is executing the pulse wave measurement mode (processing corresponding to step S307 in FIG. 20 ). That is, the control unit 52 couples and drives the sensor unit 2. Next, the control unit 52 acquires pulse wave information measured in the pulse wave measurement mode (step S400). The control unit 52 stores the pulse wave information measured in the pulse wave measurement mode in the storage unit 53.

[0167] Next, the control unit 52 determines the pulse wave period based on the acquired pulse wave information (step S401), and then determines the period of the pressure measurement mode based on the determined pulse wave period (step S402).

[0168] Fig. 29 is a diagram illustrating the operation of determining the period of the pressure measurement mode. Fig. 29 shows an example of a pulse wave. The horizontal axis of Fig. 29 represents time, and the vertical axis represents the detection signal (voltage value). The detection signal is expressed in arbitrary units.

[0169] When a user's pulse wave is measured, the pulse wave is periodic, with repeated peaks and valleys. A pulse wave peak refers to a peak of the pulse wave, and a downward-convex peak is also referred to as a pulse wave peak. A pulse wave valley refers to the portion between peaks of the pulse wave. In step S401, the control unit 52 determines the period of the pulse wave in FIG. 29. In step S402, the control unit 52 determines a period PE corresponding to the valley portion of the pulse wave.

[0170] Next, the control unit 52 determines whether the current time is in the pressure measurement mode period PE (step S403). If the current time is in the pressure measurement mode period PE (step S403 = Yes), the control unit 52 executes the pressure measurement mode (step S404). In the pressure measurement mode, the control unit 52 drives the sensor unit 2 in a divided manner.

[0171] Next, the control unit 52 determines the balance of pressures applied by the multiple fingers (pressure balance) based on the multiple detection signals measured in the pressure measurement mode of step S404 (step S405). Information on the pressure balance is stored in the storage unit 53.

[0172] If the current time is not within the pressure measurement mode period PE (step S403 = No), the control unit 52 switches from the divided drive to the connected drive and drives the sensor unit 2 in the connected drive mode (step S406). Subsequently, the control unit 52 acquires the pulse wave information measured in step S406 (step S407).

[0173] Next, the control unit 52 monitors whether the pulse wave measurement mode has ended (step S408). If the pulse wave measurement mode has not ended (step S408 = No), the control unit 52 repeats the operations from step S403 onwards.

[0174] According to the sixth embodiment, the pressure balance can be measured periodically in the pulse wave measurement mode, and the measured pressure balance can be used for pulse diagnosis.

[0175] [7] Seventh Embodiment In the seventh embodiment, the measurement device 50 further includes an air bag, and the air bag is used to apply pressure to the wrist of the user.

[0176] 30 is a plan view of a measuring device 50 according to a seventh embodiment of the present invention. The measuring device 50 includes a support member 56 and one or more air bladders 57. In this embodiment, three air bladders 57 are shown as an example.

[0177] The support member 56 is made of a flexible material and is configured, for example, as a fixing band. The support member 56 is wrapped around the wrist of the user.

[0178] The plurality of air bladders 57 are disposed below the sensor unit 2 and attached to the bottom of the support member 56. Each of the plurality of air bladders 57 is inflated by air supplied by a pump (not shown). The control unit 52 adjusts the internal pressure of each of the plurality of air bladders 57. The air bladders 57 can adjust the tightening force of the support member 56 wrapped around the user's wrist.

[0179] Pressure due to the pulse of the user is applied to air bag 57. Sensor unit 2 detects the pressure applied to air bag 57.

[0180] According to the seventh embodiment, the clamping force on the user's wrist can be adjusted using the support member 56 and the plurality of air bags 57. This makes it possible to measure the pulse wave while applying pressure to the wrist.

[0181] [8] Eighth Embodiment The eighth embodiment is an example of the configuration of a measurement system 58 including a measurement device 50.

[0182] 31 is a block diagram of a measurement system 58 according to the eighth embodiment of the present invention. The measurement system 58 includes a measurement device 50, an information processing device 59, and a management server 60.

[0183] The configuration of the measurement device 50 is the same as that of the fourth embodiment. In Fig. 31, the sensor unit 2, the control unit 52, and the communication unit 54 of the measurement device 50 are extracted and shown.

[0184] The information processing device 59 is connected to the measurement device 50 via a wired or wireless connection. The information processing device 59 is configured by a personal computer, a tablet terminal, a mobile terminal (including a smartphone), etc. The information processing device 59 has a display unit and displays information acquired from the measurement device 50 on the display unit.

[0185] The management server 60 is connected to the information processing device 59 via a wired or wireless connection. The management server 60 is configured by, for example, a personal computer. A plurality of information processing devices 59 are connected to the management server 60. The management server 60 stores and accumulates information measured by the measuring device 50. The information processing devices 59 may be connected to the management server 60 via the Internet.

[0186] The examiner (or user) operates the information processing device 59. The examiner diagnoses the user's pulse, physical condition, and health state using the measurement information measured by the measuring device 50. The examiner can also refer to past measurement information stored in the management server 60.

[0187] Although the above-described embodiments have been described using examples in which the sensor device 1 is a piezoelectric sensor, the present invention can also be applied to other types of sensors. For example, the above-described embodiments can also be applied to a pyroelectric sensor or the like.

[0188] The present disclosure is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the present disclosure. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0189] 1...sensor device, 2...sensor unit, 3...signal processing unit, 4...switch circuit, 5...amplification circuit, 6...filter circuit, 7...controller, 8...mode control unit, 9...memory unit, 10...external interface, 11...power supply control unit, 12...voltage generation circuit, 20...sensor element, 21...switch, 22...amplifier, 23...load resistance, 24...amplifier, 25...load resistance, 30...input terminal, 31...output terminal, 32, 33...resistor, 40...block, 41...switch, 50...measuring device, 51...A / D converter, 52...control unit, 53...memory unit, 54...communication unit, 55...housing, 56...support member, 57...air bag, 58...measuring system, 59...information processing device, 60...management server

Claims

1. A sensor device comprising: a sensor unit having a plurality of sensor elements; a switch circuit having a plurality of first switches connected to the plurality of sensor elements, each of which is switchable between a plurality of first paths and a plurality of second paths; an amplifier circuit having a plurality of first amplifiers connected to the plurality of first paths of the plurality of first switches, respectively, and a second amplifier connected in common to the plurality of second paths of the plurality of first switches; and a control unit that operates in a first mode and a second mode, wherein the control unit controls the switch circuit in the first mode to connect the plurality of sensor elements to the plurality of first amplifiers, respectively, and controls the switch circuit in the second mode to connect two or more sensor elements of the plurality of sensor elements to the second amplifier in common.

2. The sensor device described in claim 1, wherein the control unit selects the first mode when the voltage amplitude of at least one of the multiple detection signals of the multiple sensor elements is greater than a first threshold, and selects the second mode when the voltage amplitude of at least one of the multiple detection signals is equal to or less than the first threshold.

3. The sensor device according to claim 1, wherein the control unit switches between the first mode and the second mode based on a request from an external device.

4. The sensor device according to claim 1, further comprising: a plurality of first load resistors respectively connected to the inputs of the plurality of first amplifiers; and a second load resistor connected to the input of the second amplifier.

5. The sensor device described in claim 1 further comprising: a plurality of first load resistors respectively connected to the inputs of the plurality of first amplifiers; a second switch connected to the input of the second amplifier and switchable between a first path and a second path; a second load resistor connected to the first path of the second switch; and a third load resistor connected to the second path of the second switch and having a resistance value greater than that of the second load resistor, wherein the control unit controls the second switch based on the output voltage of the second amplifier.

6. The sensor device according to claim 5, wherein the control unit controls the second switch to switch from the second load resistor to the third load resistor when the output voltage of the second amplifier is lower than a second threshold value.

7. The sensor device according to claim 1, wherein the control unit, in the first mode, determines the position of a finger pressing against the sensor unit based on a plurality of detection signals from the plurality of sensor elements.

8. The sensor device according to claim 7, wherein the control unit determines a click operation based on the plurality of detection signals, and determines the position of the finger when the click operation is input.

9. The sensor device according to claim 7, wherein the control unit integrates the plurality of detection signals and determines the pressure applied to the sensor unit based on the integrated signal.

10. The sensor device according to claim 1, wherein in the first mode, the control unit determines the positions of the multiple fingers pressing against the sensor unit based on the multiple detection signals of the multiple sensor elements, and determines the balance of pressure of the multiple fingers.

11. The sensor device according to claim 10, wherein the control unit integrates the plurality of detection signals and determines the pressure applied to the sensor unit based on the integrated signal.

12. The sensor device according to claim 1, wherein the control unit determines whether a click operation has occurred based on a plurality of detection signals from the plurality of sensor elements, and switches from the first mode to the second mode when the click operation has been input.

13. The sensor device according to claim 12, wherein the control unit switches from the first mode to the second mode after a certain time has elapsed since the click operation was input.

14. The sensor device according to claim 1, further comprising an A / D converter connected to the output of the amplifier circuit, wherein the A / D converter samples the detection signal at each sampling period, and the sampling period in the second mode is set shorter than the sampling period in the first mode.

15. The sensor device according to claim 1, wherein the control unit determines a period of a pulse wave trough in the second mode and executes the first mode during that period.

16. A sensor device according to any one of claims 1 to 15, further comprising: a flexible support member; and an air bag provided at the bottom of the support member; wherein the sensor unit is provided at the top of the support member and is configured to detect pressure applied to the air bag.

17. A sensor device according to any one of claims 1 to 15, wherein each of the plurality of sensor elements is a piezoelectric element.

18. The sensor device according to any one of claims 1 to 15, wherein each of the plurality of sensor elements is configured using a flexible organic piezoelectric layer.

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