Proximity detection device

Abstract

Provided is a proximity detection device having a detection distance at which an object separated to some extent from an operation surface can be detected.　This proximity detection device is characterized by being provided with: a proximity detection unit that has a piezoelectric body and a first electrode and second electrode provided so as to contact the piezoelectric body and that detects the proximity of an object; a signal application unit that applies signals having a plurality of different frequencies to at least one of the first electrode and the second electrode, thereby causing the proximity detection unit to carry out electrostatic capacitance detection and ultrasonic wave transmission and / or ultrasonic wave reception; and a charge measurement unit that is connected to at least one of the first electrode and the second electrode and that measures a charge.

Description

Technical Field

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

Background Art

[0002] Conventionally, there has been a touch panel with a pressing detection function including a sensor unit including an electrostatic sensor and a piezoelectric sensor laminated on the back surface of the electrostatic sensor or sharing a part of a constituent layer with the electrostatic sensor, a capacitance detection circuit connected to the electrostatic sensor of the sensor unit for detecting the presence or absence of a touch and the touch position from a change in capacitance and sending an electrical signal to a host, a charge amplifier connected to the piezoelectric sensor of the sensor unit for converting a charge signal into a voltage signal, a sample-and-hold circuit connected to the charge amplifier for sending out the output of the charge amplifier when the capacitance detection circuit deactivates the electrostatic sensor and for holding and sending out the output of the charge amplifier immediately before the change when the capacitance detection circuit changes from deactivating the electrostatic sensor to activating it, and an AD converter connected to the sample-and-hold circuit for digitally converting the output of the sample-and-hold circuit and transmitting it to the host (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a touch panel with a pressing detection function can detect the presence or absence of a touch on a touch surface and the touch position, but cannot detect an object such as a hand that is a certain distance away from the touch surface. That is, the detectable distance for an object in a direction away from an operation surface such as a touch surface is limited.

[0005] Accordingly, an object of the present invention is to provide a proximity detection device having a detection distance capable of detecting an object located at a certain distance from an operation surface. **Means for Solving the Problem**

[0006] The proximity detection device according to an embodiment of the present invention includes a piezoelectric body, a first electrode and a second electrode provided in contact with the piezoelectric body, a proximity detection unit that detects the proximity of an object, and a signal application unit that causes the proximity detection unit to perform capacitance detection, ultrasonic transmission, and / or ultrasonic reception by applying signals of a plurality of different frequencies to at least one of the first electrode and the second electrode, and a charge measurement unit that is connected to at least one of the first electrode and the second electrode and measures electric charges. **Advantages of the Invention**

[0007] It is possible to provide a proximity detection device having a detection distance capable of detecting an object located at a certain distance from an operation surface. **Brief Description of the Drawings**

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments to which the proximity detection device of the present invention is applied will be described.

[0010] <Embodiment> FIG. 1 is a diagram showing an example of the proximity detection device 100 of the embodiment. FIG. 2 is a diagram showing an example of the configuration of the cross-sectional view taken along the line A-A in FIG. 1. Hereinafter, an explanation will be given by defining an XYZ coordinate system. The direction parallel to the X-axis (X direction), the direction parallel to the Y-axis (Y direction), and the direction parallel to the Z-axis (Z direction) are perpendicular to each other. Also, hereinafter, for convenience of explanation, the -Z direction side may be referred to as the lower side or bottom, and the +Z direction side may be referred to as the upper side or top, but it does not represent a universal up-and-down relationship. Also, a plan view means a view in the XY plane. Also, hereinafter, the lengths, thicknesses, thicknesses, etc. of each part may be exaggerated for easier understanding of the configuration.

[0011] The proximity detection device 100 includes a proximity detection unit 110, a MUX (multiplexer) 120, a transmission circuit 130, a reception circuit 140, a timer 145, and an MPU (Micro Processing Unit) 150. The MUX 120, the transmission circuit 130, and the MPU 150 are an example of a signal application unit. The signal application unit causes the proximity detection unit 110 to perform capacitance detection and ultrasonic transmission and / or ultrasonic reception by applying signals of a plurality of different frequencies to at least one of the first electrode 111 and the second electrode 112.

[0012] The proximity detection device 100 has an operation surface 100A. The operation surface 100A is a surface that serves as a reference surface when the proximity detection device 100 detects the proximity of an object, and is, for example, the surface of a panel such as the housing of an electronic device including the proximity detection device 100. The electronic device may be, for example, any electronic device including a touch panel, and examples include a smartphone and a tablet computer. The proximity detection unit 110 is located on the back side of the operation surface 100A, and the operation surface 100A is located on the front side of the proximity detection unit 110. Here, the case where the object is the hand of a user of an electronic device including the proximity detection device 100 will be described.

[0013] The proximity detection device 100 detects the proximity of the user's hand to the operation surface 100A. Here, proximity means that the hand approaches the operation surface 100A without touching it, or that the hand touches the operation surface 100A.

[0014] The proximity detection device 100 detects the amount of charge corresponding to the capacitance between the hand and the proximity detection unit 110, and calculates the position of the hand as the object by performing profile and image detection based on the amount of charge. Calculating the position of the hand based on capacitance means that it is possible to calculate the position of the hand in a state of being in contact (touching) with the operation surface 100A and the position of the hand in a state of not being in contact with the operation surface 100A but being very close to the operation surface 100A. The position of the hand calculated based on capacitance can be represented three-dimensionally.

[0015] Further, the proximity detection device 100 transmits ultrasonic waves towards the hand from a plurality of locations of the proximity detection unit 110, and calculates the distances from the operation surface 100A to a plurality of points on the hand based on the round-trip time until the reflected waves are received. That is, the proximity detection unit 110 performs ultrasonic wave reception by the reflected wave after performing ultrasonic wave transmission. The proximity detection device 100 can further calculate the distribution of the hand position from the calculated distances.

[0016] There is a limit in the direction away from the operation surface 100A in the range where the change in capacitance due to the proximity of the hand can be detected. Also, calculating the position of the hand based on the round-trip time of ultrasonic waves has a problem that it becomes difficult to calculate when the position of the hand is too close to the operation surface 100A. For this reason, when the distance from the operation surface 100A to the hand is longer than a predetermined distance, the proximity detection device 100 calculates the distance to the hand using ultrasonic waves, and when the distance from the operation surface 100A to the hand is equal to or less than the predetermined distance, it calculates the distance to the hand using capacitance. When determining whether the distance from the operation surface 100A to the hand is longer than the predetermined distance, as an example, a plurality of distances from the operation surface 100A to a plurality of points on the hand are obtained based on the round-trip time of ultrasonic waves, and it may be determined whether the average value of the plurality of distances is longer than the predetermined distance. The predetermined distance is, for example, from 3 cm to 10 cm. Also, instead of the average value of the plurality of distances, it may be determined whether the minimum value of the plurality of distances is longer than the predetermined distance, or it may be determined whether the distance at a certain point is longer than the predetermined distance.

[0017] Further, the proximity detection device 100 can calculate a two-dimensional profile representing the two-dimensional distribution of the shape of the hand, or a three-dimensional image representing the three-dimensional distribution of the shape of the hand when the user's hand approaches the operation surface 100A. Such a two-dimensional profile or three-dimensional image of the hand shape can be obtained based on the distances from the operation surface 100A to a plurality of points on the hand that can be calculated based on the round-trip time from transmitting ultrasonic waves from a plurality of locations of the proximity detection unit 110 until receiving the reflected waves.

[0018] The two-dimensional profile of the hand shape represents a two-dimensional distribution of hand positions obtained from the distribution of the Z-direction distances from the operation surface 100A to multiple positions of the hand, for example, on the XZ plane at a certain Y coordinate or on the YZ plane at a certain X coordinate. Also, the three-dimensional image of the hand shape represents a three-dimensional distribution of hand positions obtained from the distribution of the Z-direction distances from the operation surface 100A to multiple positions of the hand.

[0019] In addition, the proximity detection device 100 aims to share the detection units for detecting the distance to the hand by ultrasonic waves and the position of the hand by capacitance, and uses the MUX 120, the transmission circuit 130, the reception circuit 140, the timer 145, and the MPU 150 as the common detection units.

[0020] <Proximity detection unit 110> The proximity detection unit 110 has a piezoelectric body, and a first electrode and a second electrode provided so as to contact the piezoelectric body, and detects the proximity of an object. Note that the piezoelectric body in the present application refers to a substance having piezoelectricity, and for example, an electret having piezoelectricity is also included in the piezoelectric body. In the present embodiment, the proximity detection unit 110 has a first electrode 111, a second electrode 112, a piezoelectric body 113, and a substrate 114, and detects the proximity of the hand as the object. The first electrode 111 is a linear electrode (electrode line) extending in the X direction, and a plurality of them are arranged at equal intervals in the Y direction. The X direction is an example of the first direction, and the Y direction is an example of the second direction. The second electrode 112 is a linear electrode (electrode line) extending in the Y direction, and a plurality of them are arranged at equal intervals in the X direction. The first electrode 111 and the second electrode 112 are spaced apart in the Z direction and intersect in a plan view. At the intersection portion 110A where they intersect in a plan view, the piezoelectric body 113 is provided between the first electrode 111 and the second electrode 112. That is, the first electrode 111 and the second electrode 112 are provided so as to contact the piezoelectric body 113, and are configured such that the first electrode 111 and the second electrode 112 sandwich the piezoelectric body 113 therebetween.

[0021] The first electrode 111 and the second electrode 112 are used for both detecting the distance to the hand by ultrasonic waves and detecting the position of the hand by capacitance. The piezoelectric body 113 is used for detecting the distance to the hand by ultrasonic waves. In other words, the proximity detection unit 110 has the function of ultrasonic detection by making the electrodes for capacitance detection also serve as the electrodes of the piezoelectric body.

[0022] The intersection portion 110A where the first electrode 111 and the second electrode 112 intersect in plan view is arranged in a matrix as shown in FIG. 1. Since the substrate 114 is provided above the first electrode 111 and below the second electrode 112, the cross-sectional configuration of the intersection portion 110A is a structure in which the substrate 114, the second electrode 112, the piezoelectric body 113, the first electrode 111, and the substrate 114 are laminated from bottom to top as shown in FIG. 2.

[0023] The first electrode 111 and the second electrode 112 may be, for example, linear electrodes made of a metal such as copper or aluminum. As an example, a substrate 114 having a plurality of first electrodes 111 formed on one surface and a substrate 114 having a plurality of second electrodes 112 formed on one surface are prepared, and the piezoelectric body 113 is sandwiched at the intersection portion 110A, and the two substrates 114 are bonded together, then the proximity detection unit 110 can be manufactured. At the intersection portion 110A, the piezoelectric body 113 is disposed between the first electrode 111 and the second electrode 112, but between the first electrode 111 and the second electrode 112 outside the intersection portion 110A, it may be insulated by an insulating layer or the like.

[0024] The piezoelectric body 113 is provided to generate ultrasonic vibrations. The reason for using ultrasonic waves is that it is easy to measure the distance to the hand located directly above the piezoelectric body 113 by radiating highly directional ultrasonic waves directly above (+Z direction) each piezoelectric body 113. As the piezoelectric body 113, for example, an element that generates strain by applying a voltage, such as a piezo element, can be used. At the intersection portion 110A, since the first electrode 111 and the second electrode 112 are provided above and below the piezoelectric body 113, by applying an AC signal for ultrasonic waves between the first electrode 111 and the second electrode 112, the piezoelectric body 113 can be resonated to transmit ultrasonic waves directly above the piezoelectric body 113.

[0025] The AC signal for ultrasonic waves is an example of the second frequency signal for ultrasonic transmission, and any frequency can be used as long as it can resonate the piezoelectric body 113 disposed between the first electrode 111 and the second electrode 112. The frequency of the AC signal for ultrasonic waves is, for example, several tens of kHz to several hundreds of kHz, and the piezoelectric body 113 vibrates at a frequency equal to the frequency of the AC signal. By applying the AC signal for ultrasonic waves between the first electrode 111 and the second electrode 112, the piezoelectric body 113 can be resonated to generate ultrasonic waves of a desired frequency.

[0026] Alternatively, an electret having piezoelectricity may be used instead of the piezoelectric body 113. In this case, the electret can generate ultrasonic waves in the same manner as the piezoelectric body 113 by applying an AC signal for ultrasonic waves while being sandwiched between the first electrode 111 and the second electrode 112.

[0027] As the substrate 114, a flexible or rigid wiring substrate, an insulating sheet, or the like can be used. Also, the proximity detection unit 110 may be made transparent to visible light. In this case, the first electrode 111 and the second electrode 112 may be made of a transparent conductive material such as ITO (Indium Tin Oxide), a transparent piezoelectric body 113 may be used, and transparent substrates may be used as the two substrates 114.

[0028] <mux120> The MUX 120 is connected to the first electrode 111 and the second electrode 112 via wiring, and is also connected to the transmission circuit 130 and the reception circuit 140. The MUX 120 selects one or two or more of the plurality of first electrodes 111, and selects one or two or more of the plurality of second electrodes 112, thereby switching the first electrode 111 and the second electrode 112 connected to the transmission circuit 130 and the reception circuit 140 in a time series manner. The switching of the selection of the first electrode 111 and the second electrode 112 by the MUX 120 is performed by the MPU 150.

[0029] <Transmission circuit 130> When the transmission circuit 130 detects the distance to the hand by ultrasonic waves, it is controlled by the MPU 150 to output an AC signal for ultrasonic waves between each first electrode 111 and each second electrode 112 via the MUX 120, and also outputs an AC signal to the timer 145. Further, when performing position detection by capacitance, the transmission circuit 130 is controlled by the MPU 150 to output an AC signal having a frequency for capacitance detection to either each first electrode 111 or each second electrode 112 via the MUX 120. Since the detection of the distance to the hand by ultrasonic waves and the position detection by capacitance are performed separately, for example, in a time division manner, the transmission circuit 130 selectively applies the AC signal for ultrasonic waves and the AC signal having the frequency for capacitance detection to either each first electrode 111 or each second electrode 112.

[0030] The AC signal having a frequency for capacitance detection is an example of a first frequency signal for capacitance detection, and the AC signal for ultrasonic waves is an example of a second frequency signal for ultrasonic wave transmission. The frequency of the AC signal having a frequency for capacitance detection may be, for example, several tens of kHz to several hundreds of kHz, similar to the AC signal for ultrasonic waves, as long as it is deviated from the resonance frequency of the piezoelectric body 113. This is because the piezoelectric body 113 is not resonated when performing position detection based on capacitance.

[0031] <Reception circuit 140> The charge measurement unit is connected to at least one of the first electrode 111 and the second electrode 112 and measures the charge. In this embodiment, the receiving circuit 140 corresponds to the charge measurement unit. When detecting the distance to the hand by ultrasonic waves, the receiving circuit 140 is controlled by the MPU 150 to acquire the waveforms generated by the charges of each first electrode 111 and each second electrode 112 via the MUX 120 and output them to the timer 145. Further, when performing position detection based on capacitance, the receiving circuit 140 is controlled by the MPU 150 to detect the charge amount corresponding to the capacitance of each first electrode 111 and each second electrode 112 via the MUX 120 and output it to the MPU 150.

[0032] <Timer 145> When detecting the distance to the hand by ultrasonic waves, the timer 145 is controlled by the MPU 150 to measure, for each first electrode 111 and each second electrode 112, the time difference between the waveform of the AC signal input from the transmission circuit 130 and the waveform input from the receiving circuit 140 as the round-trip time of the ultrasonic wave. The timer 145 outputs the round-trip time measured for each first electrode 111 and each second electrode 112 to the MPU 150.

[0033] <mpu150> The MPU 150 includes a main control unit 151, a calculation unit 152, and a memory 153. The MPU 150 is implemented by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an input / output interface, an internal bus, and the like. The main control unit 151 and the calculation unit 152 represent the functions (functions) of the program executed by the MPU 150 as functional blocks. Also, the memory 153 functionally represents the memory of the MPU 150.

[0034] The main control unit 151 is a processing unit that supervises the processing of the MPU 150, and executes, for example, processing other than the processing executed by the calculation unit 152.

[0035] The calculation unit 152 calculates the distance between the object (for example, a hand) and the proximity detection unit 110. When the MPU 150 detects the distance to the hand by ultrasonic waves and when performing position detection by capacitance, the MPU 150 switches the selection of the first electrode 111 and the second electrode 112 by the MUX 120. Since the MPU 150 is connected to the first electrode 111 and the second electrode 112 selected by the MUX 120, the calculation unit 152 is connected to the first electrode 111 and the second electrode 112 selected by the MUX 120 via the transmission circuit 130 or the reception circuit 140.

[0036] The signal application unit selectively applies a first frequency signal for capacitance detection and a second frequency signal for ultrasonic transmission. The calculation unit 152 obtains the results of capacitance detection and / or ultrasonic detection based on the signal selected by the signal application unit and the charge measured by the reception circuit 140 (charge measurement unit), and calculates the distance between the object and the proximity detection unit 110 based on the obtained results. Specifically, when the first frequency signal is selected by the signal application unit, the calculation unit 152 obtains the result of capacitance detection based on the charge amount measured by the reception circuit 140, and calculates the distance between the object and the proximity detection unit 110 based on the obtained result. Further, when the second frequency signal is selected by the signal application unit, the calculation unit 152 calculates the distance between the object and the proximity detection unit 110 based on the time from ultrasonic transmission to ultrasonic reception based on the charge measured by the reception circuit 140. That is, it can be said that the calculation unit 152 is a common calculation unit capable of determining the results for both capacitance detection and ultrasonic detection by using the charge amounts of the first electrode 111 and / or the second electrode 112 measured by the charge measurement unit (reception circuit 140).

[0037] Also, the signal application unit selects the second frequency signal to cause the proximity detection unit 110 to perform ultrasonic transmission and / or reception, and when the distance between the object calculated by the calculation unit 152 and the proximity detection unit 110 becomes equal to or less than a predetermined distance, the first frequency signal is selected to cause the proximity detection unit 110 to perform capacitance detection. Specifically, as an example, the MPU 150 controls the transmission circuit 130 to output an AC signal for ultrasonic waves between each first electrode 111 and each second electrode 112 while switching the selection of the first electrode 111 and the second electrode 112 by the MUX 120 in a time series manner, and acquires the round-trip time from the timer 145. Then, the calculation unit 152 calculates the distance from the operation surface 100A directly above each intersection 110A to each part of the hand. For example, when the average value of all distances is longer than the predetermined distance, the signal application unit causes the proximity detection unit 110 to perform ultrasonic transmission and reception, thereby calculating the distance to the hand by ultrasonic waves. Further, when the average value of all distances is equal to or less than the predetermined distance, the calculation unit 152 causes the signal application unit to perform capacitance detection on the proximity detection unit 110, thereby calculating the position of the object by capacitance. Note that it is not necessarily necessary to judge based on the average value of all distances, and it may be judged based on the minimum value of all distances, or it may be judged whether it is equal to or less than the predetermined distance based on the distance between the object and the proximity detection unit 110 at a certain point. Also, in this embodiment, the timer 145 is provided separately from the MPU 150, but the MPU 150 itself may have a function of measuring time. In that case, it is not necessary to provide the timer 145.

[0038] When the MPU 150 detects the distance to the hand by ultrasonic waves, it controls the transmission circuit 130 to output an AC signal for ultrasonic waves between each first electrode 111 and each second electrode 112 while switching the selection of the first electrode 111 and the second electrode 112 by the MUX 120 in a time series manner, and causes the receiving circuit 140 to acquire the waveform generated by the charge, and acquires the round-trip time from the timer 145.

[0039] The calculation unit 152 obtains the distance from the operation surface 100A to the point where the ultrasonic wave is reflected based on the round-trip time and the speed of sound. The point where the ultrasonic wave is reflected is the part of the hand located directly above the piezoelectric body 113 at the intersection 110A of the first electrode 111 and the second electrode 112 selected by the MUX 120.

[0040] Further, the calculation unit 152 may further detect a two-dimensional profile of the hand shape or a three-dimensional image of the hand shape based on the obtained distance. Specifically, the calculation unit 152 detects a two-dimensional profile or a three-dimensional image of the hand, which is the object, based on the amount of charge measured by the reception circuit 140 (charge measurement unit) and / or the time from ultrasonic wave transmission to ultrasonic wave reception. By detecting the two-dimensional profile or the three-dimensional image, the shape of the hand can be grasped, and the movement of the user's hand can be detected.

[0041] When performing position detection by capacitance, the MPU 150 controls the transmission circuit 130 while switching the selection of the first electrode 111 and the second electrode 112 by the MUX 120 in time series, and outputs an AC signal of a frequency for capacitance detection between each first electrode 111 and each second electrode 112. At the same time, the reception circuit 140 is controlled to detect the capacitance obtained from the charges of each first electrode 111 and each second electrode 112.

[0042] Note that changing the detection method depending on whether it is a predetermined distance or more is just an example, and the MPU 150 may switch between detecting the distance to the hand by ultrasonic wave and detecting the position by capacitance in a time-division manner. In this case, it can be said that the signal application unit switches between the first frequency signal and the second frequency signal in a time-division manner. By executing the two detection methods in a time-division manner, it is possible to always perform the detection of the distance to the hand by ultrasonic wave and the detection of the position of the hand by capacitance regardless of the distance from the operation surface 100A to the hand.

[0043] The memory 153 stores programs, data necessary for the main control unit 151 and the calculation unit 152 to perform the above-described processing, the round-trip time input from the timer 145 to the MPU 150, the distance calculated by the calculation unit 152, the capacitance, data representing the two-dimensional profile or three-dimensional image of the hand shape, and the like.

[0044] <Processing executed by MPU150> FIG. 3 is a diagram showing a flowchart representing an example of the processing executed by the MPU 150.

[0045] When the calculation unit 152 starts the processing, it calculates the distance to the hand by ultrasonic waves (step S1). The calculation unit 152 calculates the distance from the operation surface 100A directly above each intersection 110A to each part of the hand. The processing in step S1 is executed to determine whether to detect the distance to the hand by ultrasonic waves or to detect the position by capacitance.

[0046] The MPU 150 determines whether the average value of all the distances is longer than a predetermined distance (step S2).

[0047] When the MPU 150 determines that the average value of all the distances is longer than the predetermined distance (S2: YES), it detects the distance to the hand by ultrasonic waves (step S3). This is because the position of the hand is too far to be detected by capacitance, so it is calculated based on the round-trip time of the ultrasonic waves. Since the details of the detection of the distance to the hand by ultrasonic waves have been described above, they are omitted here.

[0048] The calculation unit 152 detects the two-dimensional profile or three-dimensional image of the hand shape based on the distance obtained in step S2 (step S4). Thereby, a two-dimensional profile or three-dimensional image of the hand approaching the operation surface 100A is obtained.

[0049] When MPU150 finishes the process of step S4, it determines whether to end the series of processes (step S5). Determining to end the series of processes in step S5 is the case, for example, when the power of the electronic device equipped with proximity detection device 100 is turned off.

[0050] When MPU150 determines that the series of processes are not ended (S5: NO), it returns the flow to step S1. This is to continue the process according to the subsequent hand position.

[0051] Also, in step S2, when MPU150 determines that the average value of all distances is not longer than the predetermined distance (S2: NO), it performs position detection by capacitance (step S6). This is because the hand position is close to being obtained by the round-trip time of ultrasonic waves, so it is obtained by capacitance. Note that when MPU150 finishes the process of step S6, it advances the flow to step S5.

[0052] As described above, proximity detection device 100 provides piezoelectric body 113 at intersection portion 110A of first electrode 111 and second electrode 112. When the hand position is at or below the predetermined distance, it performs position detection by capacitance obtained from the charges of first electrode 111 and second electrode 112. When the hand position is longer than the predetermined distance, it calculates the distance to the hand based on the round-trip time of the ultrasonic wave transmitted by driving piezoelectric body 113. In the detection of the distance to the hand by ultrasonic waves, it can detect a distance far enough that cannot be realized by position detection by capacitance.

[0053] Therefore, it is possible to provide proximity detection device 100 having a detection distance capable of detecting an object that is separated from operation surface 100A to a certain extent.

[0054] In addition, the proximity detection device 100 aims to share the detection units for detecting the distance to the hand by ultrasonic waves and the position of the hand by capacitance. The common detection units are the MUX 120, the transmission circuit 130, the reception circuit 140, the timer 145, and the MPU 150. In particular, the reception circuit 140 can, by taking on the role of a charge measurement unit, detect the charge necessary in common for capacitance detection and ultrasonic detection in one configuration. For this reason, the detection of the distance to the hand by ultrasonic waves and the detection of the position of the hand by capacitance can be executed by the same circuit, and with a simple configuration, the position of the hand near the operation surface 100A based on capacitance and the position of the hand at a certain distance from the operation surface 100A using ultrasonic waves can be obtained. Also, by executing the detection of the distance to the hand by ultrasonic waves and the detection of the position of the hand by capacitance in the same detection unit, the detection accuracies of the two different detection methods can be made uniform. This is a solution to the problem that if the detection of the distance to the hand by ultrasonic waves and the detection of the position of the hand by capacitance are performed by separate detection units, the device configuration becomes complex and large-sized.

[0055] Also, since the proximity detection unit 110 is configured such that the first electrode 111 and the second electrode 112 sandwich the piezoelectric body 113 therebetween, an AC signal can be easily applied to the piezoelectric body 113 using the first electrode 111 and the second electrode 112 for capacitance detection. Note that the proximity detection unit 110 may be configured such that the first electrode 111 and the second electrode 112 sandwich an electret having piezoelectricity therebetween. Also, since the MUX 120, the transmission circuit 130, the reception circuit 140, and the MPU 150 connected to the first electrode 111 and the second electrode 112 are used for capacitance detection, a proximity detection device 100 capable of ultrasonic detection can be realized only by adding the timer 145 and changing the program executed by the MPU 150. This is a solution to the problem that if the detection of the distance to the hand by ultrasonic waves and the detection of the position of the hand by capacitance are performed by separate proximity detection units, the device configuration becomes complex and large-sized.

[0056] In addition, since the proximity detection unit 110 performs ultrasonic reception by reflected waves after performing ultrasonic transmission, it is not necessary to provide separate proximity detection units for transmission and reception. Ultrasonic transmission and reception can be performed by one proximity detection unit 110, and ultrasonic transmission and reception can be realized with a simple configuration.

[0057] Also, the signal application unit selectively applies a first frequency signal for capacitance detection and a second frequency signal for ultrasonic transmission. In this embodiment, the MPU 150, MUX 120, and transmission circuit 130 corresponding to the signal application unit selectively apply an AC signal for capacitance detection and an AC signal for ultrasonic transmission. The calculation unit 152 obtains the results of capacitance detection and / or ultrasonic detection based on the signal selected by the signal application unit (MPU 150, MUX 120, and transmission circuit 130) and the measured charge, and calculates the distance between the hand, which is the object, and the proximity detection unit 110 based on the obtained results. Therefore, a simple configuration can be realized in which one MUX 120, one transmission circuit 130, and one reception circuit 140 can be used for both capacitance detection and ultrasonic detection.

[0058] Further, the signal application unit (MPU 150, MUX 120, and transmission circuit 130) selects an AC signal for ultrasonic transmission and causes the proximity detection unit 110 to perform ultrasonic transmission and reception. When the distance between the object and the proximity detection unit 110 calculated by the calculation unit 152 becomes equal to or less than a predetermined distance, the signal application unit selects an AC signal for capacitance detection and causes the proximity detection unit 110 to perform capacitance detection. Thus, a simple configuration can be realized in which one proximity detection unit 110, one MUX 120, one transmission circuit 130, and one reception circuit 140 can be used for both capacitance detection and ultrasonic detection.

[0059] The timer 145 further measures the time (round-trip time) from when the transmission circuit 130 applies the second frequency signal until the charge based on the AC signal for ultrasonic transmission reflected by the object is measured by the reception circuit 140. The calculation unit 152 calculates the distance between the object and the proximity detection unit 110 based on the time measured by the timer 145. Therefore, the distance to the hand, which is the object, can be easily detected based on the round-trip time of the ultrasonic wave.

[0060] In addition, since the transmission circuit 130 and the reception circuit 140 can also switch between the AC signal for capacitance detection and the AC signal for ultrasonic detection by time division, a simple configuration can be realized in which one transmission circuit 130 and one reception circuit 140 can be used for both capacitance detection and ultrasonic detection by time division.

[0061] As described above, the proximity detection unit 110 only needs to include one piezoelectric body 113, one first electrode 111, and one second electrode 112 provided in contact with the piezoelectric body 113. Therefore, it is not necessarily the case that a plurality of first electrodes 111 and a plurality of second electrodes 112 are essential as shown in FIG. 1. However, in order to detect the two-dimensional profile or three-dimensional image of the object, distance data at a plurality of points is required. Therefore, as shown in FIG. 1, the proximity detection unit 110 can include a plurality of first electrodes 111 and a plurality of second electrodes 112. In this case, it includes a plurality of first electrodes 111, one or more piezoelectric bodies 113, and a plurality of second electrodes 112. Each of the one or more piezoelectric bodies 113 is provided between at least one of the plurality of first electrodes 111 and at least one of the plurality of second electrodes 112. Therefore, by transmitting and receiving ultrasonic waves with one or more piezoelectric bodies 113 provided between the plurality of first electrodes 111 and the plurality of second electrodes 112, the distance to the hand, which is the object, can be measured. Here, the case where there is one piezoelectric body 113 is, for example, the case where a sheet layer of the piezoelectric body 113 is provided over the entire surface between the layer provided with the first electrode 111 and the layer provided with the second electrode 112.

[0062] The first electrode 111 extends in the X direction and is arranged in a plurality in the Y direction intersecting the X direction. The second electrode 112 extends in the Y direction and is arranged in a plurality in the X direction. Since the piezoelectric body 113 is provided so as to be sandwiched between the first electrode 111 and the second electrode 112 at the intersection portion 110A where the first electrode 111 and the second electrode 112 intersect, an AC signal for ultrasonic transmission can be easily applied to the piezoelectric body 113 by using the first electrode 111 and the second electrode 112 for capacitance detection, and a reflected wave can be easily detected, realizing a configuration. Note that the capacitance detection may be performed by self-capacitance detection or mutual-capacitance detection. Further, the first electrode 111 and the second electrode 112 do not necessarily have to intersect. For example, a configuration in which a plurality of piezoelectric bodies 113 sandwiched between the first electrode 111 and the second electrode 112 are arranged side by side on a plane may be used.

[0063] In addition, since the calculation unit 152 detects a two-dimensional profile or a three-dimensional image of the object based on the measured charge amount, it is possible to provide the proximity detection device 100 that can easily grasp the shape and movement of the hand, which is an object near the operation surface 100A. That is, the proximity detection device 100 performs detailed image detection of the object by using both capacitance detection and ultrasonic detection, and performs capacitance detection in a region close to touch and ultrasonic detection in a region at a certain distance, enabling object detection at distances in a wide range.

[0064] In the above description, the form in which the proximity detection unit 110 includes a plurality of first electrodes 111, a plurality of second electrodes 112, and one or more piezoelectric bodies 113 has been described. However, the proximity detection unit 110 may have a configuration including one first electrode 111, one second electrode 112, and one piezoelectric body 113 as the minimum configuration. The number of the first electrodes 111 and the number of the second electrodes 112 do not have to be equal.

[0065] In addition, in the above description, the form in which the piezoelectric body 113 is provided at each of the intersections 110A between the plurality of first electrodes 111 and the plurality of second electrodes 112 has been described. However, the intersections 110A where the piezoelectric body 113 is provided may be a part of all the intersections 110A. For example, in the X direction and / or the Y direction, the piezoelectric body 113 may be provided at every other intersection 110A. Since the number of piezoelectric bodies 113 is related to the detection of the hand position in ultrasonic detection, the two-dimensional profile, and the resolution of the three-dimensional image, it may be appropriately set according to the application of the proximity detection device 100 or the like.

[0066] That is, each of the one or more piezoelectric bodies 113 may be provided between at least any one of the plurality of first electrodes 111 and at least any one of the plurality of second electrodes 112.

[0067] <Modified Example of Intersection 110A> Figures 4A to 7C are diagrams showing modified examples of the intersection 110A. Figures 4A to 7C show configurations corresponding to a cross-section (the cross-section taken along the line A-A in Figure 1) corresponding to the cross-section of the intersection 110A shown in Figure 2. The intersection 110A shown in Figure 2 may be deformed into the configuration shown in any of Figures 4A to 7C.

[0068] The intersection 110A in Figure 4A has a first electrode 111, a second electrode 112, a piezoelectric body 113, and a substrate 114. The intersection 110A in Figure 4A has a configuration in which the uppermost substrate 114 of the intersection 110A shown in Figure 2 is omitted. For example, the piezoelectric body 113 and the first electrode 111 may be provided on top of the substrate 114 with the second electrode 112 formed on one surface.

[0069] The intersection 110A in Figure 4B has a first electrode 111, a second electrode 112, a piezoelectric body 113, and two substrates 114, and has a configuration in which the piezoelectric body 113 of the intersection 110A shown in Figure 2 is made thinner.

[0070] The intersection 110A in Figure 4C has a first electrode 111, a second electrode 112, a piezoelectric body 113, and two substrates 114, and has a configuration in which the first electrode 111 and the second electrode 112 of the intersection 110A shown in Figure 2 are made thinner.

[0071] The intersection 110A in FIG. 4D has a first electrode 111, a second electrode 112, a piezoelectric body 113, and two substrates 114, and has a configuration in which the piezoelectric body 113 of the intersection 110A shown in FIG. 2 is divided into two.

[0072] The intersection 110A in FIG. 5A has a first electrode 111, a second electrode 112, a piezoelectric body 113, and two substrates 114, and in the cross section shown in FIG. 5A, has a configuration in which the first electrode 111 of the intersection 110A shown in FIG. 2 is divided into two. The first electrode 111 may be divided into two, or for example, the first electrode 111 may have a shape that spirals in a plan view.

[0073] The intersection 110A in FIG. 5B has a first electrode 111, a second electrode 112, a piezoelectric body 113, and two substrates 114, and has a configuration in which the piezoelectric body 113 shown in FIG. 5A is divided into two.

[0074] The intersection 110A shown in FIG. 5C has a first electrode 111, a second electrode 112, a piezoelectric body 113, two substrates 114, and a shield electrode 115. The shield electrode 115 is an example of a third electrode for shielding. In the intersection 110A shown in FIG. 5C, the second electrode 112 is arranged on the piezoelectric body 113 together with the first electrode 111, and the shield electrode 115 is formed on the lower substrate 114, and the piezoelectric body 113 is provided on the shield electrode 115. The shield electrode 115 is provided on the side opposite to the side where the operation surface 100A, which is the object, the hand is close to, with respect to the first electrode 111 and the second electrode 112.

[0075] The first electrode 111 and the second electrode 112 are electrodes patterned in a diamond shape in a plan view, and in FIG. 5C, the portions of the first electrode 111 and the second electrode 112 that cross each other are omitted.

[0076] The shield electrode 115 is provided to shield the first electrode 111 and the second electrode 112 on the operation surface 100A side from noise and to suppress the parasitic capacitance with the ground. An AC voltage may be applied, or it may be connected to the ground. When an AC voltage is applied, it can be said that the signal application unit applies a third frequency signal to the third electrode (shield electrode 115). When performing capacitance detection, the signal application unit can also give the shield electrode 115 the function as an active shield by setting the frequency of the third frequency signal to the same frequency as the frequency of the first frequency signal. The shield electrode 115 is composed of, for example, a metal foil made of copper or aluminum, or a conductive film made of a transparent conductive material such as an ITO film. The shield electrode 115 is a single electrode provided over the entire proximity detection unit 110 in a plan view. Applying an AC voltage to such a shield electrode 115 is when detecting the position of the hand by capacitance.

[0077] The intersection 110A shown in FIG. 5D has a configuration in which the piezoelectric body 113 of the intersection 110A shown in FIG. 5C is divided into the first electrode 111 and the second electrode 112. For example, ultrasonic waves may be transmitted by the first electrode 111 and received by the second electrode 112.

[0078] The intersection 110A shown in FIG. 6A has a configuration in which the piezoelectric body 113 under the second electrode 112 is removed from the intersection 110A shown in FIG. 5D. The intersection 110A shown in FIG. 6B has a configuration in which the first electrode 111 and the second electrode 112 of the intersection 110A shown in FIG. 6A are made thinner.

[0079] The intersection 110A shown in FIG. 7A includes a first electrode 111, a second electrode 112, a piezoelectric body 113, three substrates 114, a shield electrode 115, and an OCA (Optical Clear Adhesive) 116. The intersection 110A shown in FIG. 7A has a structure in which the shield electrode 115, the OCA 116, the substrate 114, the second electrode 112, the piezoelectric body 113, the first electrode 111, and the substrate 114 are stacked on the bottommost substrate 114. In other words, the intersection 110A shown in FIG. 7A has a structure in which a third substrate 114 with a shield electrode 115 provided on one surface is adhered with the OCA 116 under the substrate 114 on the lower side of the intersection 110A shown in FIG. 2. Similar to the intersection 110A in FIG. 5C, an AC voltage may be applied to the shield electrode 115 when detecting the position of the hand by capacitance.

[0080] The intersection 110A shown in FIG. 7B has a structure in which the substrate 114 on the top of the intersection 110A shown in FIG. 7A is removed. In other words, the intersection 110A shown in FIG. 7B has a structure in which a third substrate 114 with a shield electrode 115 provided on one surface is adhered with the OCA 116 under the intersection 110A shown in FIG. 4A.

[0081] The intersection 110A shown in FIG. 7C has a structure in which the substrate 114 under the second electrode 112 of the intersection 110A shown in FIG. 7A is removed, and the substrate 114 provided with the shield electrode 115 is turned upside down. The substrate 114 provided with the shield electrode 115 may be turned upside down compared to FIG. 7A with the shield electrode 115 facing down, and then adhered under the second electrode 112 with the OCA 116.

[0082] <Proximity Detection Device 100M of the Modified Example of the Embodiment> FIG. 8 is a diagram showing an example of a proximity detection device 100M of a modified example of the embodiment. The proximity detection device 100M includes a proximity detection unit 110M instead of the proximity detection unit 110 shown in FIG. 1. Other configurations are the same as those of the proximity detection device 100 shown in FIG. 1. Here, the differences will be described.

[0083] The proximity detection unit 110M has a configuration in which a piezoelectric body 113A used for transmitting ultrasonic waves and a piezoelectric body 113B used for receiving ultrasonic waves are respectively arranged between the first electrode 111 and the second electrode 112 at the intersection portions 110B1 and 110B2, instead of providing the piezoelectric body 113 at all the intersection portions 110A between the first electrode 111 and the second electrode 112 as in the proximity detection unit 110 of FIG. 1.

[0084] The intersection portion 110B1 and the intersection portion 110B2 are arranged so as to include every other different first electrode 111 among the plurality of first electrodes 111. Also, the intersection portion 110B1 and the intersection portion 110B2 are arranged so as to include every other different first electrode 111 among the plurality of second electrodes 112.

[0085] And the intersection portion 110B1 and the intersection portion 110B2 are positioned so as not to be adjacent to each other in the X direction and the Y direction in a plan view and to be arranged obliquely. The piezoelectric body 113A used for transmitting ultrasonic waves and the piezoelectric body 113B used for receiving ultrasonic waves have the same configuration as the piezoelectric body 113 of the proximity detection device 100.

[0086] In the proximity detection device 100M having such a configuration, when transmitting ultrasonic waves, the first electrode 111 and the second electrode 112 included in the intersection portion 110B1 are selected by the MUX 120 and an AC signal for ultrasonic waves is applied, so that an AC signal for ultrasonic waves may be applied to the piezoelectric body 113A.

[0087] Also, when receiving ultrasonic waves, the first electrode 111 and the second electrode 112 included in the intersection portion 110B2 are selected by the MUX 120, and a waveform generated by the charges of the first electrode 111 and the second electrode 112 may be acquired by the receiving circuit 140.

[0088] The method of performing position detection by capacitance in the proximity detection device 100M is the same as the method of performing position detection by capacitance in the proximity detection device 100.

[0089] By separating the piezoelectric body 113A used for transmitting ultrasonic waves and the piezoelectric body 113B used for receiving ultrasonic waves, as in the proximity detection device 100M of the modification example of the embodiment, the switching control of the MUX 120 and the control for acquiring waveforms in the receiving circuit 140 when detecting the distance to the hand by ultrasonic waves are simplified, and there are advantages such as easy improvement of the device performance by separating the transmitting and receiving functions.

[0090] As described above, the proximity detection device according to the exemplary embodiment of the present invention has been described. However, the present invention is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0091] This international application claims priority based on Japanese Patent Application No. 2021-077787 filed on April 30, 2021, and the entire content thereof is incorporated herein by reference.

Explanation of Reference Numerals

[0092] 100, 100M Proximity Detection Device 110, 110M Proximity Detection Unit 110A, 110B1, 110B2 Intersection 111 First Electrode 112 Second Electrode 113 Piezoelectric Body 115 Shield Electrode 120 MUX 130 Transmission Circuit 140 Receiving Circuit 145 Timer 150 MPU 152 Calculation Unit

Claims

1. A proximity detection unit that has a piezoelectric body, a first electrode and a second electrode provided so as to be in contact with the piezoelectric body, and that detects the proximity of an object, A signal application unit that causes the proximity detection unit to perform capacitance detection, ultrasonic transmission, and / or ultrasonic reception by applying signals of a plurality of different frequencies to at least one of the first electrode and the second electrode, A charge measurement unit that is connected to at least one of the first electrode and the second electrode and measures electric charge, A calculation unit that calculates the distance between the object and the proximity detection unit is provided, The signal application unit selectively applies a first frequency signal for capacitance detection and a second frequency signal for ultrasonic transmission, The calculation unit obtains the result of capacitance detection and / or ultrasonic detection based on the signal selected by the signal application unit and the electric charge measured by the charge measurement unit, and calculates the distance between the object and the proximity detection unit based on the obtained result. A proximity detection device characterized by this.

2. The proximity detection device according to claim 1, wherein the proximity detection unit is configured such that the first electrode and the second electrode sandwich the piezoelectric body therebetween.

3. The proximity detection device according to claim 1 or 2, wherein the proximity detection unit performs ultrasonic reception by a reflected wave after performing the ultrasonic transmission.

4. The calculation unit obtains the result of capacitance detection based on the amount of electric charge measured by the charge measurement unit when the first frequency signal is selected by the signal application unit, and based on the obtained result, calculates the distance between the object and the proximity detection unit. The proximity detection device according to any one of claims 1 to 3, characterized by this.

5. The calculation unit calculates the distance between the object and the proximity detection unit based on the time from ultrasonic transmission to ultrasonic reception based on the electric charge measured by the charge measurement unit when the second frequency signal is selected by the signal application unit. The proximity detection device according to any one of claims 1 to 4, characterized by this.

6. The signal application unit selects the second frequency signal to cause the proximity detection unit to perform ultrasonic transmission and / or ultrasonic reception, and when the distance between the object and the proximity detection unit calculated by the calculation unit becomes equal to or less than a predetermined distance, selects the first frequency signal to cause the proximity detection unit to perform capacitance detection. The proximity detection device according to any one of claims 1 to 5, characterized in that.

7. The signal application unit switches between the first frequency signal and the second frequency signal by time division. The proximity detection device according to any one of claims 1 to 5, characterized in that.

8. The signal application unit further includes a timer that measures the time from when the second frequency signal is applied until the charge based on the second frequency signal reflected by the object is measured. The calculation unit calculates the distance between the object and the proximity detection unit based on the time measured by the timer. The proximity detection device according to any one of claims 1 to 7, characterized in that.

9. The calculation unit detects a two-dimensional profile or a three-dimensional image of the object based on the amount of charge measured by the charge measurement unit and / or the time from ultrasonic transmission to ultrasonic reception. The proximity detection device according to any one of claims 1 to 8, characterized in that.

10. A plurality of the first electrodes, One or more of the piezoelectric bodies, A plurality of the second electrodes are provided, Each of the one or more piezoelectric bodies is provided between at least one of the plurality of first electrodes and at least one of the plurality of second electrodes. The proximity detection device according to any one of claims 1 to 9, characterized in that.

11. The first electrode extends in a first direction and is arranged in a plurality in a second direction intersecting the first direction. The second electrode extends in the second direction and is arranged in a plurality in the first direction. The piezoelectric body is provided so as to be sandwiched between the first electrode and the second electrode at a location where the first electrode and the second electrode intersect. The proximity detection device according to any one of claims 1 to 10, characterized in that.

12. The proximity detection device according to any one of claims 1 to 11, further comprising a third electrode provided on a side opposite to the side where the object approaches the first electrode and the second electrode.

13. The third electrode is connected to the ground. The proximity detection device according to claim 12, characterized in that.

14. The proximity detection device according to claim 12, wherein the signal application unit applies a third frequency signal to the third electrode.

15. The proximity detection device according to any one of claims 1 to 14, wherein the piezoelectric body is an electret having piezoelectricity.

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