Input device

Abstract

Provided is an input device enabling measurement of a load based on strain and an electrostatic capacity by one measurement circuit.　The input device comprises a load sensor, an electrostatic sensor, and a measurement circuit. The load sensor includes: a first voltage divider circuit in which a first strain sensor is connected to a second strain sensor; a first capacitor having one end connected to a connection point between the first strain sensor and the second strain sensor; a second voltage divider circuit in which a third strain sensor is connected to a fourth strain sensor; and a second capacitor having one end connected to a connection point between the third strain sensor and the fourth strain sensor. The electrostatic sensor includes a plurality of electrostatic sensor electrodes. The measurement circuit includes: an AC voltage circuit applying an AC voltage to the first voltage divider circuit, the second voltage divider circuit, and the electrostatic sensor electrodes; a charge amplifier provided at respective subsequent stages of the first capacitor, the second capacitor, and the plurality of electrostatic sensor electrodes; and a control circuit calculating a measured value from an output of the charge amplifier.

Description

Input Devices

[0001] The present disclosure relates to input devices.

[0002] Conventionally, there has been a multi-directional input device that includes a mounting plate, an elastic substrate placed on the mounting plate, a plurality of strain detection members formed on the elastic substrate, and an operating body for operating the strain detection members, and is characterized in that the mounting plate and the elastic substrate are fixed at a welding portion (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 10-049293

[0004] However, conventional multi-directional input devices can detect the load applied to the operating body based on distortion, but cannot detect capacitance, and therefore cannot measure both the load based on distortion and capacitance using a single measurement circuit.

[0005] Therefore, an object of the present invention is to provide an input device that can measure a load based on distortion and electrostatic capacitance using a single measurement circuit.

[0006] An input device according to an embodiment of the present disclosure includes a load sensor, an electrostatic sensor, and a measurement circuit. The load sensor includes a first voltage divider circuit connecting a first strain sensor and a second strain sensor, a first capacitor having one end connected to a connection point between the first strain sensor and the second strain sensor, a second voltage divider circuit connecting a third strain sensor and a fourth strain sensor, and a second capacitor having one end connected to a connection point between the third strain sensor and the fourth strain sensor. The electrostatic sensor has a plurality of electrostatic sensor electrodes. The measurement circuit includes an AC voltage circuit that applies an AC voltage to the first voltage divider circuit, the second voltage divider circuit, and the electrostatic sensor electrodes, charge amplifiers provided downstream of each of the first capacitor, the second capacitor, and the plurality of electrostatic sensor electrodes, and a control circuit that calculates a measurement value from the output of the charge amplifier.

[0007] It is possible to provide an input device that can measure a load based on strain and capacitance using a single measurement circuit.

[0008] It is a figure which shows an example of the structure of the input device of the embodiment. It is a figure which shows an example of the circuit structure of the input device of the embodiment. It is a figure which shows an example of the structure of the input device of a modified example of the embodiment. It is a figure which shows an example of the structure of the input device of another modified example of the embodiment.

[0009] Hereinafter, an embodiment to which the input device of the present disclosure is applied will be described.

[0010] In the following description, the XYZ coordinate system is defined. 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. Furthermore, a planar view refers to a view from the XY plane. In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand.

[0011] 1 is a diagram showing an example of the configuration of an input device 100 according to an embodiment. As an example, the input device 100 is a game machine for personal use, but it may also be a personal computer (PC), a tablet-type input device placed in a store or facility and used by an unspecified number of users, or an input section of an automatic teller machine (ATM).

[0012] <Outline of Input Device 100> Fig. 1 is a perspective view of the appearance of an input device 100 according to an embodiment. The input device 100 shown in Fig. 1 is used in, for example, a game machine, and is operated by an operator (i.e., a game player).

[0013] 1, the input device 100 includes a housing 110. The housing 110 is a resin member that forms the outer shape of the input device 100. Inside the housing 110, a strain-generating body is provided that is distorted when the touchpad unit 120 is operated (tilted, rotated, or pressed).

[0014] The housing 110 has a central portion 110A, a left grip portion 110B provided to the left of the central portion 110A (negative side of the Y axis), and a right grip portion 110C provided to the right of the central portion 110A (positive side of the Y axis). The left grip portion 110B and the right grip portion 110C are longer in the front-to-rear direction (X axis direction) than the central portion 110A and have a shape that protrudes rearward (negative side of the X axis) beyond the rear surface of the central portion 110A.

[0015] This allows the housing 110 to be shaped so that the operator can easily hold the left grip portion 110B with the left hand and the right grip portion 110C with the right hand.

[0016] Furthermore, a recess 110D recessed downward (in the negative direction of the Z axis) from an upper surface 110E of the housing 110 is formed at the front end (the end on the positive side of the X axis) of the central portion 110A of the housing 110. The input device 100 includes a touchpad unit 120 in the recess 110D of the housing 110. The touchpad unit 120 is an example of an electrostatic sensor.

[0017] In plan view from above (positive direction of the Z axis), both the recess 110D and the touchpad unit 120 have a rectangular shape with the longitudinal direction extending in the left-right direction (Y axis direction). The rectangular shape of the touchpad unit 120 is smaller than the rectangular shape of the recess 110D of the upper housing 111. As a result, a gap is provided between the outer periphery of the touchpad unit 120 and the inner periphery of the recess 110D.

[0018] Furthermore, an upper surface 110E (the surface on the positive side of the Z axis) of the housing 110 and an upper surface 120A (the surface on the positive side of the Z axis) of the touchpad unit 120 are provided on the same plane.

[0019] The touchpad unit 120 has a rectangular touch operation surface 120B on an upper surface 120A (the surface on the positive side of the Z axis) with its longitudinal direction extending in the left-right direction (the Y axis direction). The touchpad unit 120 allows an operator to perform a touch operation on the touch operation surface 120B.

[0020] The touchpad unit 120 is provided so as to be displaceable relative to the housing 110, and can be pressed, tilted, and rotated by the operator.

[0021] Note that the pressing operation on the touchpad unit 120 refers to pressing downward (in the negative Z-axis direction) the center of the touch operation surface 120B of the touchpad unit 120. The pressing operation applies a compressive load downward (in the negative Z-axis direction) to the touchpad unit 120 while keeping it horizontal.

[0022] The tilting operation of the touchpad unit 120 refers to pressing downward (in the negative direction of the Z axis) the peripheral portion (portion other than the center) of the touch operation surface 120B of the touchpad unit 120. The tilting operation applies a bending load to the touchpad unit 120 about a central axis (central axis parallel to the Z axis) passing through the center of the touchpad unit 120.

[0023] Furthermore, the rotation operation of the touchpad unit 120 is an operation of twisting the touchpad unit 120 around a central axis (central axis parallel to the Z axis) that passes through the center of the touchpad unit 120. By the rotation operation, a torsional load is applied to the touchpad unit 120 around the central axis (central axis parallel to the Z axis) that passes through the center of the touchpad unit 120.

[0024] Furthermore, the input device 100 may be equipped with other input devices such as a plurality of buttons, an analog stick, etc. in addition to the touchpad unit 120. Furthermore, the input device 100 may be a device that is operated by tilting a stick.

[0025] 2A is a diagram showing an example of a circuit configuration of the input device 100 according to the embodiment. The input device 100 includes a touchpad unit 120, load sensors 130A and 130B, and a measurement circuit 140.

[0026] The load sensors 130A and 130B are attached to a strain-generating body provided inside the housing 110. The strain-generating body is distorted when the touchpad unit 120 is operated (tilted, rotated, or pressed).

[0027] As an example, the input device 100 can measure the amount of tilting and pressing based on the output of the load sensor 130A, and can measure the amount of rotation based on the output of the load sensor 130B. The configurations of the touchpad unit 120, the load sensors 130A and 130B, and the measurement circuit 140 will be described below.

[0028] <Touchpad Unit 120> The touchpad unit 120 has a plurality of sensor electrodes 121X extending in the X direction, a plurality of sensor electrodes 121Y extending in the Y direction, wiring 122X and 122Y, and an active shield electrode 123. The sensor electrodes 121X and 121Y are an example of electrostatic sensor electrodes, and are connected to the MUX 141 of the measurement circuit 140 via the wiring 122X and 122Y, respectively. The sensor electrodes 121X and 121Y are arranged overlapping the active shield electrode 123 on the +Z direction side and are insulated from the active shield electrode 123. The touchpad unit 120 shown in FIG. 2A is a self-capacitance electrostatic sensor.

[0029] For example, the sensor electrodes 121X, 121Y and the wiring 122X, 122Y can be fabricated by forming a conductive film such as a metal film on the surface of an insulating substrate and patterning the sensor electrodes 121X, 121Y and the wiring 122X, 122Y. The active shield electrode 123 can be fabricated by forming a conductive film such as a metal film on the surface of another insulating substrate. When a display is disposed on the −Z direction side of the touchpad unit 120, a transparent glass plate or the like can be used as the insulating substrate, and a transparent conductive film such as ITO (Indium Tin Oxide) can be used as the conductive film.

[0030] The plurality of sensor electrodes 121X are scanned row by row, and the plurality of sensor electrodes 121Y are scanned column by column, and the control circuit 145 converts the capacitances at the plurality of intersections of the plurality of sensor electrodes 121X and the plurality of sensor electrodes 121Y into digital values. Note that, instead of the sensor electrodes 121X and 121Y, a plurality of sensor electrodes arranged in an array may be used and scanned in sequence.

[0031] The active shield electrode 123 is formed without gaps over an entire area larger than the areas where the sensor electrodes 121X and 121Y are provided. The active shield electrode 123 is connected to an AC signal source 144 and is driven by an AC signal having the same frequency and phase as the AC components contained in the signals supplied to the sensor electrodes 121X and 121Y. The amplitude of the AC signal supplied to the active shield electrode 123 is larger than the amplitude of the AC components of the signals supplied to the sensor electrodes 121X and 121Y.

[0032] The active shield electrode 123 is provided to shield the multiple sensor electrodes 121X, 121Y from noise and to suppress the effects of parasitic capacitance. The active shield electrode 123 is arranged near the multiple sensor electrodes 121X, 121Y and overlaps them at a predetermined interval so as to shield the multiple sensor electrodes 121X, 121Y from noise mainly from ground potential points such as the ground and to suppress the effects of parasitic capacitance between the multiple sensor electrodes and the ground potential points.

[0033] The input device 100 may not include the touchpad unit 120 .

[0034] <Load Sensor 130A> The load sensor 130A has a voltage divider circuit 131 including strain sensors R1 and R2, a voltage divider circuit 132 including strain sensors R3 and R4, a capacitor C1, and a capacitor C2. The voltage divider circuit 131 is an example of a first voltage divider circuit, and the voltage divider circuit 132 is an example of a second voltage divider circuit. The strain sensors R1 to R4 are examples of a first to fourth strain sensors, respectively. The capacitor C1 is an example of a first capacitor, and the capacitor C2 is an example of a second capacitor.

[0035] The strain sensors R1 to R4 are, for example, strain resistance elements whose resistance value changes depending on the amount of strain, and are connected to form a bridge circuit. Capacitor C1 is connected to the connection point of strain sensors R1 and R2, and capacitor C2 is connected to the connection point of strain sensors R3 and R4.

[0036] The strain sensors R1 and R3 are connected to an AC signal source 144, and the strain sensors R2 and R4 are connected to ground. The capacitors C1 and C2 are connected to the input terminals of a MUX (multiplexer) 141.

[0037] <Load Sensor 130B> The load sensor 130B has a voltage divider circuit 133 including strain sensors R5 and R6, a voltage divider circuit 134 including strain sensors R7 and R8, a capacitor C3, and a capacitor C4. The voltage divider circuit 134 is an example of a third voltage divider circuit, and the voltage divider circuit 134 is an example of a fourth voltage divider circuit. The strain sensors R5 to R8 are examples of the fifth to eighth strain sensors, respectively. The capacitor C3 is an example of a third capacitor, and the capacitor C4 is an example of a fourth capacitor.

[0038] The strain sensors R5 to R8 are, for example, strain resistance elements whose resistance value changes depending on the amount of strain, and are connected to form a bridge circuit. Capacitor C3 is connected to the connection point of strain sensors R5 and R6, and capacitor C4 is connected to the connection point of strain sensors R7 and R8.

[0039] The strain sensors R5 and R7 are connected to an AC signal source 144, and the strain sensors R6 and R8 are connected to ground. The capacitors C3 and C4 are connected to the input terminals of a MUX (multiplexer) 141.

[0040] The input device 100 may include either one of the load sensors 130A and 130B.

[0041] <Measurement Circuit 140> The measurement circuit 140 includes an MUX 141, a charge amplifier 142, an input circuit 143, an AC signal source 144, a control circuit 145, and an I / F (Interface) 146. The AC signal source 144 is an example of an AC voltage circuit. The measurement circuit 140 is configured with an IC (Integrated Circuit).

[0042] The measurement circuit 140 is, for example, an IC designed and developed for the touchpad unit 120, and is realized as a single packaged IC chip. The MUX 141, the charge amplifier 142, the input circuit 143, the AC signal source 144, the control circuit 145, and the I / F 146 are built into the measurement circuit 140, which is configured as an IC chip.

[0043] In the input device 100, the capacitance is measured through the touchpad unit 120 using the measurement circuit 140 for the touchpad unit 120, and the load is measured through the load sensors 130A and 130B including the strain sensors R1 to R8.

[0044] In order to measure the load using the measurement circuit 140 designed and developed for the touchpad unit 120, the load sensors 130A and 130B are provided with capacitors C1 to C4 for converting changes in the resistance values ​​of the strain sensors R1 to R8 into changes in the amount of charge. By converting changes in the resistance values ​​of the strain sensors R1 to R8 into changes in the amount of charge, it becomes possible to measure changes in the resistance values ​​of the strain sensors R1 to R8 without making any changes to the measurement circuit 140 for the touchpad unit 120.

[0045] <MUX 141> The MUX 141 is connected to the subsequent stages (output sides) of the capacitors C1 to C4 and all of the sensor electrodes 121X and 121Y. More specifically, the capacitors C1 and C2 are connected to two input terminals of the common MUX 141. The capacitors C3 and C4 are connected to two input terminals of the common MUX 141. The same number of sensor electrodes 121X and 121Y are provided, and each is connected to two input terminals of the common MUX 141.

[0046] <Charge Amplifiers 142> The same number of charge amplifiers 142 as MUXs 141 are provided, and one charge amplifier 142 is connected to the output side of each MUX 141. The charge amplifier 142 connected to capacitors C1 and C2 via MUX 141 outputs a signal representing the amount of charge in capacitors C1 and C2. The charge amplifier 142 connected to capacitors C3 and C4 via MUX 141 outputs a signal representing the amount of charge in capacitors C3 and C4. The charge amplifier 142 connected to sensor electrodes 121X and 121Y via MUX 141 outputs a signal representing the amount of charge in sensor electrodes 121X and 121Y.

[0047] Although FIG. 2A shows a circuit configuration in which one charge amplifier 142 is connected to the output side of each MUX 141, a configuration in which one common multiplexer (MUX) is provided on the output side of all MUXs 141 and one input circuit 143 is connected to the output side of this MUX may also be used.

[0048] <Input Circuit 143> The number of input circuits 143 provided is the same as the number of charge amplifiers 142, and one input circuit 143 is connected to the output side of each charge amplifier 142. The input circuit 143 performs digital conversion processing and the like on the signal output from the charge amplifier 142 and outputs the result to the control circuit 145.

[0049] <AC Signal Source 144> The AC signal source 144 is connected to the strain sensors R1, R3, R5, and R7 and the active shield electrode 123. The AC signal source 144 generates a sinusoidal AC signal to be applied to the strain sensors R1 to R8 and the active shield electrode 123. In addition, a signal containing an AC component having the same frequency and phase as the AC signal supplied to the active shield electrode 123 but a smaller amplitude than the AC signal supplied to the active shield electrode 123 is supplied from the control circuit 145 to the sensor electrodes 121X and 121Y. Note that the AC signal source 144 only needs to output an AC signal, and may therefore be configured to output, for example, a rectangular wave AC signal.

[0050] <Control Circuit 145> The control circuit 145 is realized by a computer including a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an input / output interface, an internal bus, etc. As an example of the control circuit 145, an MPU (Micro Processing Unit) can be used.

[0051] The control circuit 145 is connected to all of the input circuits 143 and the AC signal source 144. The control circuit 145 has a multiplexer function that combines multiple signals input from multiple input circuits 143 connected to all of the sensor electrodes 121X, 121Y into one signal.

[0052] The control circuit 145 controls the driving of the AC signal source 144, measures the load based on the signal input from the input circuit 143 connected to the voltage divider circuits 131 and 132, and measures the coordinates based on the signal input from the input circuit 143 connected to the sensor electrodes 121X and 121Y. The coordinates measured are the position of the operating object, such as a fingertip, relative to the operating surface.

[0053] <Modification of input device 100> Fig. 2B is a diagram showing an example of the configuration of the input device 100 according to a modification of the embodiment. The input device 100 shown in Fig. 2B differs from the input device 100 shown in Fig. 2A in that the touchpad unit 120 is of a mutual capacitance type.

[0054] <Touchpad Unit 120> The touchpad unit 120 has a plurality of sensor electrodes 121X extending in the X direction, a plurality of sensor electrodes 121Y extending in the Y direction, and wirings 122X and 122Y, but does not have an active shield electrode 123 (see FIG. 2A).

[0055] The sensor electrodes 121X and 121Y are examples of electrostatic sensor electrodes. The sensor electrode 121X is connected to a charge amplifier 142 via a wiring 122X, and the sensor electrode 121Y is connected to an AC signal source 144 via a wiring 122Y.

[0056] The plurality of sensor electrodes 121X are scanned row by row, and the plurality of sensor electrodes 121Y are scanned column by column, and the control circuit 145 converts the capacitances at the plurality of intersections of the plurality of sensor electrodes 121X and the plurality of sensor electrodes 121Y into digital values. Note that, instead of the sensor electrodes 121X and 121Y, a plurality of sensor electrodes arranged in an array may be used and scanned in sequence.

[0057] <Load Sensors 130A, 130B> The configurations of the load sensors 130A, 130B are the same as the configuration of the load sensors 130A, 130B of the input device 100 shown in FIG. 2A.

[0058] <Measurement Circuit 140> The measurement circuit 140 includes a charge amplifier 142, an input circuit 143, an AC signal source 144, a control circuit 145, and an I / F 146, but does not include the MUX 141 (see FIG. 2A).

[0059] <Charge Amplifiers 142> Of all the charge amplifiers 142, the connection relationship of four charge amplifiers 142 connected to capacitors C1 to C4 is the same as the connection relationship shown in Fig. 2A. Each of the remaining charge amplifiers 142 is connected to one sensor electrode 121Y.

[0060] The input circuit 143 is the same as the input circuit 143 shown in Fig. 2A. The AC signal source 144 is connected to the strain sensors R1, R3, R5, and R7 and all of the sensor electrodes 121X.

[0061] 2B, the AC signal source 144 outputs an AC signal having a rectangular wave shape, for example. However, the AC signal source 144 may be configured to output an AC signal having a sine wave shape.

[0062] The control circuit 145 is the same as the control circuit 145 shown in FIG. 2A in that it is connected to all of the input circuits 143 and the AC signal source 144, but differs from the control circuit 145 shown in FIG. 2A in that it has the function of a multiplexer that combines multiple signals input from multiple input circuits 143 connected to all of the sensor electrodes 121Y into one signal.

[0063] The control circuit 145 controls the driving of the AC signal source 144, measures the load based on the signal input from the input circuit 143 connected to the voltage divider circuits 131 and 132, and measures the coordinates based on the signal input from the input circuit 143 connected to the sensor electrodes 121X and 121Y.

[0064] Regardless of whether the circuit configuration of the input device 100 is that of Figure 2A or Figure 2B, the capacitance can be measured through the touchpad unit 120 using the measurement circuit 140 for the touchpad unit 120, and the load can be measured through the load sensors 130A and 130B, which include strain sensors R1 to R8.

[0065] Capacitors C1 to C4 for converting changes in the resistance values ​​of strain sensors R1 to R8 into changes in the amount of charge are provided in load sensors 130A and 130B, and by converting changes in resistance values ​​into changes in the amount of charge, it becomes possible to measure changes in the resistance values ​​of strain sensors R1 to R8 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, measurement circuit 140 for touchpad unit 120 can measure the loads of tilting operations, rotation operations, and pressing operations performed by load sensors 130A and 130B.

[0066] <Another Modification of Input Device 100> Fig. 2C is a diagram showing an example of the configuration of an input device 100 according to another modification of the embodiment. The input device 100 shown in Fig. 2C differs from the input device 100 shown in Fig. 2A in that the touchpad unit 120 includes a plurality of sensor electrodes 121X extending in the X direction and wiring 122X, but does not include a plurality of sensor electrodes 121Y extending in the Y direction and wiring 122Y. Note that the touchpad unit 120 shown in Fig. 2C may include an active shield electrode 123.

[0067] The input device 100 shown in Fig. 2C also differs from the input device 100 shown in Fig. 2A in that it includes one load sensor 130A but does not include load sensor 130B. The load sensor 130A also differs from the input device 100 shown in Fig. 2A in that it includes one voltage divider circuit 131 but does not include voltage divider circuit 132. The voltage divider circuit 131 of the input device 100 shown in Fig. 2C has two strain sensors R1 and R2.

[0068] 2A in that the input device 100 shown in FIG. 2C does not include the MUX 141, the charge amplifier 142 is directly connected to the input circuit 143, and the capacitor connected to the connection point of the strain sensors R1 and R2 is directly connected to the input circuit 143.

[0069] 2C is capable of detecting coordinates in the Y direction using a plurality of sensor electrodes 121X, and for example, if a load sensor 130A is provided below the touchpad unit 120, it is possible to measure the load (pressure operation amount) applied to the touchpad unit 120 based on the output of the load sensor 130A. Furthermore, if the load sensor 130A is made capable of detecting the load in the X direction, it becomes possible for the input device 100 shown in FIG. 2C to detect an operation of moving a finger in the Y direction and an operation of pressing with a finger in the X direction.

[0070] <Effects> The input device 100 includes a load sensor 130A, a touchpad unit 120 (electrostatic sensor), and a measurement circuit 140. The load sensor 130A includes a voltage divider circuit 131 (first voltage divider circuit) that connects the strain sensor R1 (first strain sensor) and the strain sensor R2 (second strain sensor), and a capacitor C1 (first capacitor) that has one end connected to the connection point between the strain sensor R1 and the strain sensor R2. The touchpad unit 120 includes a plurality of sensor electrodes 121X (electrostatic sensor electrodes). The measurement circuit 140 includes an AC signal source 144 (AC voltage circuit) that applies an AC voltage to the voltage divider circuit 131 and the sensor electrode 121X, a charge amplifier 142 provided downstream of the capacitor C1 and each of the plurality of sensor electrodes 121X and 121Y, and a control circuit 145 that calculates a measurement value from the output of the charge amplifier 142.

[0071] Load sensor 130A is provided with capacitor C1 for converting changes in resistance value of strain sensors R1 to R2 into changes in charge amount, and by converting changes in resistance value into changes in charge amount, it becomes possible to measure changes in resistance value of strain sensors R1 to R2 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, one measurement circuit 140 can measure coordinates by touchpad unit 120 and load during operation by load sensor 130A.

[0072] Therefore, it is possible to provide an input device 100 that can measure the load based on the strain and the capacitance with a single measurement circuit 140 .

[0073] In addition, the load sensor 130A further includes a voltage divider circuit 132 (second voltage divider circuit) that connects the strain sensor R3 (third strain sensor) and the strain sensor R4 (fourth strain sensor), and a capacitor C2 (second capacitor) that has one end connected to the connection point between the strain sensor R3 and the strain sensor R4, the measurement circuit 140 further includes a charge amplifier 142 that is provided downstream of the capacitor C2, and the AC signal source 144 (AC voltage circuit) may further apply an AC voltage to the voltage divider circuit 132.

[0074] Load sensor 130A is provided with capacitors C1 and C2 for converting changes in resistance of strain sensors R1 to R4 into changes in charge, and by converting changes in resistance into changes in charge, it becomes possible to measure changes in resistance of strain sensors R1 to R4 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, one measurement circuit 140 can measure coordinates using touchpad unit 120 and load during operation using load sensor 130A.

[0075] Therefore, it is possible to provide an input device 100 that can measure the load based on the strain and the capacitance with a single measurement circuit 140 .

[0076] The input device 100 includes a load sensor 130A and a measurement circuit 140. The load sensor 130A has a voltage divider circuit 131 (first voltage divider circuit) that connects the strain sensors R1 and R2, and a capacitor C1 (first capacitor) that has one end connected to the connection point between the strain sensors R1 and R2. The measurement circuit 140 has an AC signal source 144 (AC voltage circuit) that applies an AC voltage to the voltage divider circuit 131, a charge amplifier 142 that is provided downstream of the capacitor C1, and a control circuit 145 that calculates a measurement value from the output of the charge amplifier 142.

[0077] Load sensor 130A is provided with capacitor C1 for converting changes in resistance value of strain sensors R1 to R2 into changes in charge amount, and by converting changes in resistance value into changes in charge amount, it becomes possible to measure changes in resistance value of strain sensors R1 to R2 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, measurement circuit 140 for touchpad unit 120 can measure the load during operation by load sensor 130A.

[0078] Therefore, it is possible to provide the input device 100 that can measure the load based on the distortion with the measurement circuit 140 for the touch pad unit 120 .

[0079] In addition, the load sensor 130A further includes a voltage divider circuit 132 (second voltage divider circuit) that connects the strain sensor R3 (third strain sensor) and the strain sensor R4 (fourth strain sensor), and a capacitor C2 (second capacitor) that has one end connected to the connection point between the strain sensor R3 and the strain sensor R4, the measurement circuit 140 further includes a charge amplifier 142 that is provided downstream of the capacitor C2, and the AC signal source 144 (AC voltage circuit) may further apply an AC voltage to the voltage divider circuit 132.

[0080] Load sensor 130A is provided with capacitors C1 and C2 for converting changes in resistance of strain sensors R1 to R4 into changes in charge, and by converting changes in resistance into changes in charge, it becomes possible to measure changes in resistance of strain sensors R1 to R4 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, one measurement circuit 140 can measure coordinates using touchpad unit 120 and load during operation using load sensor 130A.

[0081] Therefore, it is possible to provide an input device 100 that can measure the load based on the strain and the capacitance with a single measurement circuit 140 .

[0082] Furthermore, the measurement circuit 140 is configured with an IC capable of detecting the capacitance of the touchpad unit 120, and the AC signal source 144 and the charge amplifier 142 may be built into the IC. By not using an IC dedicated to the strain sensor, the number of IC types can be reduced, making inventory management easier. Furthermore, if an IC for the touchpad unit 120 is already available, the cost of designing an IC is unnecessary. Furthermore, since IC design is not required, the development period can be shortened.

[0083] The load sensors 130A and 130B also include a voltage divider circuit 133 (third voltage divider circuit) that connects the strain sensor R5 (fifth strain sensor) and the strain sensor R6 (sixth strain sensor), a capacitor C3 (third capacitor) that has one end connected to the connection point between the strain sensor R5 and the strain sensor R6, a voltage divider circuit 134 (fourth voltage divider circuit) that connects the strain sensor R7 (seventh strain sensor) and the strain sensor R8 (eighth strain sensor), a capacitor C4 (fourth capacitor) that has one end connected to the connection point between the strain sensor R7 and the strain sensor R8, and a capacitor C3 and a charge amplifier 142 provided in the subsequent stage of each of capacitors C1 and C2, and the control circuit 145 may detect a load in the first direction from the output of charge amplifier 142 based on the output of voltage divider circuit 131, detect a load in the second direction from the output of charge amplifier 142 based on the output of voltage divider circuit 132, detect a load in the first rotation direction from the output of charge amplifier 142 based on the output of voltage divider circuit 133, and detect a load in the second rotation direction from the output of charge amplifier 142 based on the output of voltage divider circuit 134.

[0084] Capacitors C1 to C4 for converting changes in the resistance values ​​of strain sensors R1 to R8 into changes in the amount of charge are provided in load sensors 130A and 130B, and by converting changes in resistance values ​​into changes in the amount of charge, it becomes possible to measure changes in the resistance values ​​of strain sensors R1 to R8 without making any changes to measurement circuit 140 for touchpad unit 120. Therefore, measurement circuit 140 for touchpad unit 120 can measure the loads of tilting operations, rotation operations, and pressing operations performed by load sensors 130A and 130B.

[0085] The above describes an input device according to an exemplary embodiment of the present disclosure, but the present disclosure is not limited to the specifically disclosed embodiment, and various modifications and variations are possible without departing from the scope of the claims.

[0086] This international application claims priority based on Japanese Patent Application No. 2023-173868, filed on October 5, 2023, the entire contents of which are incorporated herein by reference.

[0087] 100 Input device 120 Touch pad unit (an example of an electrostatic sensor) 121X, 121Y Sensor electrode (an example of an electrostatic sensor electrode) 123 Active shield electrode 130A, 130B Load sensor 131 to 134 Voltage divider circuit (an example of a first voltage divider circuit to a fourth voltage divider circuit) R1 to R8 Strain sensor (an example of a first strain sensor to an eighth strain sensor) C1 to C4 Capacitor (an example of a first capacitor to a fourth capacitor) 131 to 134 Voltage divider circuit (an example of a first voltage divider circuit to a fourth voltage divider circuit) 140 Measuring circuit 142 Charge amplifier 144 AC signal source (an example of an AC voltage circuit) 145 Control circuit

Claims

1. An input device comprising: a load sensor; an electrostatic sensor; and a measurement circuit, wherein the load sensor comprises: a first voltage divider circuit connecting a first strain sensor and a second strain sensor; and a first capacitor having one end connected to a connection point between the first strain sensor and the second strain sensor, the electrostatic sensor comprises a plurality of electrostatic sensor electrodes, and the measurement circuit comprises: an AC voltage circuit which applies an AC voltage to the first voltage divider circuit and the electrostatic sensor electrodes, a charge amplifier provided downstream of the first capacitor and each of the plurality of electrostatic sensor electrodes, and a control circuit which calculates a measurement value from the output of the charge amplifier.

2. An input device as described in claim 1, wherein the load sensor further has a second voltage divider circuit connecting a third strain sensor and a fourth strain sensor, and a second capacitor having one end connected to a connection point between the third strain sensor and the fourth strain sensor, the measurement circuit further has a charge amplifier provided downstream of the second capacitor, and the AC voltage circuit further applies an AC voltage to the second voltage divider circuit.

3. An input device comprising: a load sensor; and a measurement circuit, wherein the load sensor has a first voltage dividing circuit connecting a first strain sensor and a second strain sensor; and a first capacitor having one end connected to a connection point between the first strain sensor and the second strain sensor, and the measurement circuit has: an AC voltage circuit which applies an AC voltage to the first voltage dividing circuit; a charge amplifier provided in the subsequent stage of the first capacitor; and a control circuit which calculates a measured value from the output of the charge amplifier.

4. An input device as described in claim 3, wherein the load sensor further has a second voltage divider circuit connecting a third strain sensor and a fourth strain sensor, and a second capacitor having one end connected to a connection point between the third strain sensor and the fourth strain sensor, the measurement circuit further has a charge amplifier provided downstream of the second capacitor, and the AC voltage circuit further applies an AC voltage to the second voltage divider circuit.

5. An input device according to any one of claims 1 to 4, wherein the measurement circuit is composed of an IC capable of detecting the capacitance of the electrostatic sensor, and the AC voltage circuit and the charge amplifier are built into the IC.

6. The input device according to claim 2 or 4, wherein the load sensor further comprises: a third voltage divider circuit connecting a fifth strain sensor and a sixth strain sensor; a third capacitor having one end connected to a connection point between the fifth strain sensor and the sixth strain sensor; a fourth voltage divider circuit connecting a seventh strain sensor and an eighth strain sensor; a fourth capacitor having one end connected to a connection point between the seventh strain sensor and the eighth strain sensor; and charge amplifiers provided downstream of each of the third capacitor and the fourth capacitor, and the control circuit detects a load in a first direction from an output of the charge amplifier based on an output of the first voltage divider circuit, detects a load in a second direction from an output of the charge amplifier based on an output of the second voltage divider circuit, detects a load in a first rotation direction from an output of the charge amplifier based on the output of the third voltage divider circuit, and detects a load in a second rotation direction from an output of the charge amplifier based on the output of the fourth voltage divider circuit.

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