Capacitive input device

Abstract

To provide a capacitive input device configured to prevent a reference value from being updated to an incorrect value when an operation of a finger stopped in contact with a sensor surface is falsely determined to be non-proximity operation.SOLUTION: A capacitive input device includes: a plurality of capacitive sensor electrodes; a measurement circuit which outputs measurement values based on capacitance between each of the capacitive sensor electrodes and a pointer; a control unit which determines whether the pointer is in proximity state which indicates proximity to the capacitive sensor electrode, based on the measurement values output by the measurement circuit; and a storage unit which stores, as reference values, measurement values in a state where the pointer is not in proximity to the capacitive sensor electrodes. The control unit determines a proximity state based on a first difference value obtained by subtracting a reference value from a measurement value, calculates a total difference value obtained by summing a plurality of first difference values of the capacitive sensor electrodes, and updates, in the proximity state, the reference values when the amount of change in total difference value is continuously kept smaller than a predetermined value for a predetermined time or longer after the total difference value decreases.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to electrostatic input devices. [Background technology]

[0002] Conventionally, there has been a touch detection device that includes a sensor electrode that detects a detection capacitance corresponding to a touch operation, an operation determination unit that determines a touch operation based on the detection capacitance obtained using a reference value as a measurement standard and a touch determination threshold and a non-touch determination threshold that are determined from the range of the detection capacitance relative to the reference value, and a threshold adjustment unit that adjusts the non-touch determination threshold if a capacitance fluctuation value that is the difference between the detection capacitance and the reference value is within the range of the touch determination threshold and the non-touch determination threshold and if a capacitance fluctuation range that is the swing range of the detection capacitance is less than the fluctuation range threshold (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-116331 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional touch detection device, when a finger is stopped while in contact with the sensor surface during a touch operation, the reference value is updated and there is a risk that the device may erroneously determine that no touch operation is being performed.

[0005] Therefore, the object of the present invention is to provide an electrostatic input device that can prevent a situation in which, when a finger is stopped while in contact with the sensor surface, it is erroneously determined that no proximity operation is being performed, and the reference value is updated to an incorrect value. [Means for solving the problem]

[0006] An electrostatic input device according to an embodiment of the present disclosure includes a plurality of electrostatic sensor electrodes, a measurement circuit that outputs a measurement value based on the capacitance between each of the plurality of electrostatic sensor electrodes and a pointer, a control unit that determines whether the pointer is in a proximity state in which it is close to the plurality of electrostatic sensor electrodes based on the measurement value output by the measurement circuit, and a memory unit that stores the measurement value when the pointer is not in proximity to the plurality of electrostatic sensor electrodes as a reference value, and the control unit determines whether the proximity state is present based on a first difference value obtained by subtracting the reference value from the measurement value, calculates a total difference value by adding up the first difference values ​​of the plurality of electrostatic sensor electrodes, and updates the reference value when, in the proximity state, the amount of change in the total difference value is smaller than a predetermined value after the total difference value has decreased and continues for a predetermined period of time or more. [Effects of the Invention]

[0007] It is possible to provide an electrostatic input device that can prevent a reference value from being updated to an incorrect value when a finger is stopped while in contact with the sensor surface and is erroneously determined not to be performing a proximity operation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 illustrates an example of a configuration of an electrostatic input device according to an embodiment. [Figure 2] FIG. 1 illustrates an example of a configuration of an electrostatic input device according to an embodiment. [Figure 3] FIG. 4 is a state transition diagram illustrating an example of an operation of the electrostatic input device according to the embodiment. [Figure 4A] 10 is a flowchart illustrating an example of a process executed by a control unit of the electrostatic input device according to the embodiment. [Figure 4B] 10 is a flowchart illustrating an example of a process executed by a control unit of the electrostatic input device according to the embodiment. [Figure 4C] 10 is a flowchart illustrating an example of a process executed by a control unit of the electrostatic input device according to the embodiment. [Figure 4D] 10 is a flowchart illustrating an example of a process executed by a control unit of the electrostatic input device according to the embodiment. [Figure 5] FIG. 10 is a diagram illustrating an example of a configuration of an electrostatic input device according to a first modified example of the embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a configuration of an electrostatic input device according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] In the following explanation, 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 on the XY plane. In the following explanation, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand.

[0011] <Embodiment> 1 and 2 are diagrams showing an example of the configuration of an electrostatic input device 100 according to an embodiment.

[0012] The electrostatic input device 100 is, for example, an input unit provided in the center console of a vehicle for adjusting the volume of an audio system or the temperature or airflow of an air conditioner, and the volume, temperature, airflow, etc. can be adjusted by operating a slider 111, which serves as a GUI (Graphical User Interface) switch, for example. The electrostatic input device 100 may also be an input unit of a tablet-type input device or an ATM (Automatic Teller Machine) that is placed in a store, facility, etc. and used by an unspecified number of users. The electrostatic input device 100 may also be a tablet computer, smartphone, game console, etc. for personal use.

[0013] <Overall Configuration of Electrostatic Input Device 100> The electrostatic input device 100 includes a housing 101 , a top panel 105 , a display 110 , an electrostatic sensor 120 , a measurement circuit 125 A, an image display circuit 125 B, a control device 130 , and a temperature sensor 140 .

[0014] 1, the electrostatic sensor 120 is located on the rear side (-Z direction side) of the top panel 105, and the display 110 is located on the rear side (-Z direction side) of the electrostatic sensor 120. Also, although the measurement circuit 125A, the image display circuit 125B, the control device 130, and the temperature sensor 140 (see FIG. 2) are omitted in FIG. 1, the measurement circuit 125A, the image display circuit 125B, the control device 130, and the temperature sensor 140 are provided inside the housing 101 on the rear side (-Z direction side) of the display 110, as an example.

[0015] 2, the housing 101 and the top panel 105 are omitted, and the display 110 is shown larger than the electrostatic sensor 120. Also, in FIG. 2, the slider 111 displayed on the display 110 is omitted, and the electrostatic sensor electrode 121 of the electrostatic sensor 120 is shown transparently. Also, in FIG. 2, XYZ coordinates of the display 110 and the electrostatic sensor 120 are shown.

[0016] <Chassis 101 and top panel 105> The housing 101 is a case made of resin, metal, or the like that houses the display 110, the electrostatic sensor 120, the measurement circuit 125A, the image display circuit 125B, the control device 130, and the temperature sensor 140. The display 110 is arranged, for example, below the transparent electrostatic sensor 120, and is visible through an operation surface 105A, which is the upper surface of a transparent top panel 105 provided in an opening at the top of the housing 101. The operation surface 105A is an example of a sensor surface.

[0017] A user operates the capacitive input device by bringing a pointer, such as a hand, close to the capacitive sensor 120. By adjusting the sensitivity of the capacitive sensor 120 and the thickness of the top panel 105, the capacitive input device can be operated with the pointer in contact with the operation surface 105A. In other words, the state in which the pointer is in contact with the operation surface 105A can be considered to be in proximity. Furthermore, by adjusting the sensitivity of the capacitive sensor 120 and the thickness of the top panel 105, the capacitive input device can be operated without the pointer touching the operation surface 105A. The capacitance (measured value) measured by the measurement circuit 125A fluctuates when the temperature of the capacitive sensor electrode 121 of the capacitive sensor 120 changes. When the product temperature is low, the temperature of the capacitive sensor 120 rises when the user's hand (pointer) touches the operation surface 105A. Furthermore, in a small space such as a vehicle interior, the temperature of the capacitive sensor 120 may change suddenly due to heating. The capacitive input device 100 of the present invention can suppress the effects of such temperature changes.

[0018] The temperature of the electrostatic sensor electrode of the electrostatic sensor 120 rises when, for example, a pointer such as a user's hand continues to touch the cold operation surface 105A for a relatively long time (for example, 2 to 10 seconds), such as during a slide operation. Although the temperature can rise in cases other than a slide operation, the following describes a case in which the user performs a slide operation on the slider 111. Also, even when a pointer such as a user's hand is not in contact with the operation surface 105A, a temperature rise due to heating can occur. In the following, the term "proximity" is used to mean a state in which a pointer such as a user's hand is in contact with the operation surface 105A, and a state in which the pointer is very close to but separated from the operation surface 105A. In either case, the pointer is in proximity to the electrostatic sensor 120.

[0019] In the following, as an example, a form in which the user operates the electrostatic input device 100 with the fingertips FT of the hand will be described, but the electrostatic input device 100 can also be operated with parts of the user's body other than the fingertips FT of the hand.

[0020] <Display 110> Examples of the display 110 include a liquid crystal display and an organic EL (Electroluminescence) display. The display 110 is a display unit for realizing a GUI (Graphical User Interface). The display 110 displays GUI images of a slider 111 and a frame 111A. The frame 111A indicates the range within which the slider 111 can be moved. The display 110 may also display GUI buttons, a cursor, and the like in addition to the slider 111.

[0021] <Electrostatic sensor 120, measurement circuit 125A, image display circuit 125B> The electrostatic sensor 120 is disposed on top of the display 110, and has a plurality of electrostatic sensor electrodes 121 arranged along the X direction, as shown in FIG. 2. Each of the electrostatic sensor electrodes 121 extends in the Y direction. A measurement circuit 125A is connected to the electrostatic sensor 120. An image display circuit 125B is connected to the display 110. The measurement circuit 125A is provided between the electrostatic sensor 120 and the control device 130. The image display circuit 125B is provided between the display 110 and the control device 130.

[0022] The electrostatic sensor electrode 121 is connected to the control device 130 via a measurement circuit 125A. Such an electrostatic sensor 120 can be formed by forming a transparent conductive film such as ITO (Indium Tin Oxide) on the surface of transparent glass and patterning it into the electrostatic sensor electrode 121. The electrostatic capacitance of the electrostatic sensor 120 is input to the measurement circuit 125A. Five electrostatic sensor electrodes 121 are shown in FIGS. 1 and 2 as an example. The five electrostatic sensor electrodes 121 are arranged at positions overlapping with the slider 111 and the frame 111A, as shown in FIG. 1.

[0023] The measurement circuit 125A is mounted on a wiring board. The measurement circuit 125A is provided between the electrostatic sensor 120 and the control device 130, and performs AD (Analog to Digital) conversion on the capacitance of each electrostatic sensor electrode 121. The measurement circuit 125A outputs the capacitance (measured value) of each electrostatic sensor electrode 121 to the control device 130.

[0024] The measurement circuit 125A scans the multiple electrostatic sensor electrodes 121 one by one, converts the capacitance of each electrostatic sensor electrode 121 into a digital value, and calculates a difference value ΔAD for each electrostatic sensor electrode 121 by subtracting a reference value. The difference value ΔAD is a count value of the change in the output of the measurement circuit 125A from the reference value. The reference value is a value proportional to the capacitance of the electrostatic sensor electrode 121 when there is no target object such as a fingertip FT around the electrostatic sensor electrode 121. The measurement circuit 125A calculates the difference value ΔAD by subtracting the reference value from the measured value of the capacitance of each electrostatic sensor electrode 121.

[0025] The image display circuit 125B is provided between the display 110 and the control device 130, and displays GUI images of the slider 111 and the frame 111A on the display 110 in accordance with image data sent from the control device 130.

[0026] <Control device 130> The control device 130 has a control unit 131 and a memory 132. The control device 130 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. The control unit 131 represents the functions of a program executed by the control device 130 as a functional block. The memory 132 is a functional representation of the memory of the control device 130, and is an example of a storage unit.

[0027] <Control unit 131> The control unit 131 controls the operation of the electrostatic input device 100. The control unit 131 receives the difference value ΔAD from the measurement circuit 125A and calculates the X coordinate of the fingertip FT. The X coordinate of the fingertip FT calculated by the control unit 131 is the X coordinate of any one of the multiple electrostatic sensor electrodes 121. The X coordinate of the electrostatic sensor electrode 121 is, for example, the X coordinate of the center of the electrostatic sensor electrode 121. The control unit 131 controls the display of an image on the display 110 via the image display circuit 125B. The control unit 131 outputs the operation amount of the slider 111 operated by the fingertip FT to an ECU (Electronic Control Unit) that controls the audio, air conditioning, etc. of the vehicle.

[0028] <Memory 132> The memory 132 stores a reference value used by the measurement circuit 125A when calculating the difference value ΔAD. As described above, the reference value is a value proportional to the capacitance of the electrostatic sensor electrode 121 when there is no target object such as a fingertip FT around the electrostatic sensor electrode 121, and therefore varies depending on the temperature of the electrostatic sensor electrode 121.

[0029] If the reference value is not updated in accordance with the temperature fluctuation of the electrostatic sensor electrode 121, the control unit 131 will not be able to correctly calculate the difference value ΔAD when the temperature of the electrostatic sensor electrode 121 fluctuates. For this reason, the electrostatic input device 100 updates the reference value in a predetermined state. This will be described in detail later using a flowchart, etc.

[0030] <Temperature sensor 140> The temperature sensor 140 detects, for example, the temperature inside a vehicle in which the electrostatic input device 100 is installed. The temperature inside the vehicle is an example of the ambient temperature of the electrostatic sensor electrode 121. The temperature sensor 140 is connected to the control device 130, and the temperature detected by the temperature sensor 140 is input to the control unit 131 of the control device 130.

[0031] <State transition diagram showing the operation of the electrostatic input device 100> FIG. 3 is a state transition diagram showing an example of the operation of the electrostatic input device 100. Here, the state of the electrostatic input device 100 will be described starting from the off state. The control unit 131 performs control processing, and the state of the electrostatic input device 100 transitions as follows. In the following, the difference value ΔAD will be referred to as the difference value ΔCapacity. The difference value ΔAD and the difference value ΔCapacity are the same. The difference value ΔAD and the difference value ΔCapacity are examples of a first difference value.

[0032] <Off state> The off state is a state in which the power of the electrostatic input device 100 is on, but the fingertip FT is not in contact (touching) with the operation surface 105A, and the electrostatic input device 100 does not detect a touch operation of the fingertip FT on the operation surface 105A.

[0033] The off state is a state in which the control unit 131 determines that no touch operation is being performed on the operation surface 105A of the fingertip FT, and is one of the proximity states of the electrostatic input device 100. The proximity state of the electrostatic input device 100 has two states: off and on. When the proximity state is on, a touch operation is being performed on the operation surface 105A of the fingertip FT. When the proximity state is off, a touch operation is not being performed on the operation surface 105A of the fingertip FT. In the off state, the reference value is updated by a well-known method.

[0034] <Transition from Off to On via 1)On> In the OFF state, when the difference value ΔCapacity exceeds the ON threshold ThOn, the state of the electrostatic input device 100 transitions to the ON state along 1) On. The ON threshold ThOn is an example of a proximity threshold. The ON state is a state in which the difference value ΔCapacity exceeds the ON threshold ThOn and the control unit 131 determines that the fingertip FT is touching the operation surface 105A, and the proximity state of the electrostatic input device 100 is ON. The ON threshold ThOn is a threshold for determining whether the proximity state is ON.

[0035] <Transition from the On state to On_NormalTemperature along 2a) NormalTemperature> When the temperature inside the vehicle detected by the temperature sensor 140 is higher than the temperature threshold in the On state, the state of the electrostatic input device 100 transitions to the On_NormalTemperature state along 2a) NormalTemperature. The temperature threshold is, for example, 15°C and is a threshold for determining whether the temperature is low. The temperature threshold is the temperature at the boundary where the change in sensitivity of the electrostatic sensor electrode 121 becomes non-negligible when the fingertip FT touches the operation surface 105A and the temperature of the sensor electrode 121 rises.

[0036] When the temperature is low and the temperature of the electrostatic sensor electrode 121 is low, if the slider 111 is operated for a relatively long time of about several seconds to 10 seconds, the temperature of the electrostatic sensor electrode 121 rises due to the temperature of the fingertip FT, and the measured value of the capacitance of the electrostatic sensor electrode 121 increases. Therefore, the control unit 131 performs control processing according to the temperature inside the vehicle detected by the temperature sensor 140.

[0037] When the temperature inside the vehicle detected by the temperature sensor 140 is higher than the temperature threshold, since there is no risk of mis-calculation of the difference value ΔCapacity, the control unit 131 transitions to the On_NormalTemperature state in order to perform control processing in the normal state.

[0038] <Transition from the On_NormalTemperature state to Off along 3a) Off> In the On_NormalTemperature state, when the maximum value of the five difference values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is lower than the off threshold, the state of the electrostatic input device 100 transitions to the Off state along 3a) Off. The off threshold is a threshold for determining whether the proximity state is off.

[0039] <Transition from the On state to On_LowTemperature along 4) LowTemperature> When the in-vehicle temperature detected by the temperature sensor 140 is lower than the temperature threshold value in the On state, the state of the electrostatic input device 100 transitions to the On_LowTemperature state along 4) LowTemperature. In the On_LowTemperature state, the control unit 131 performs control processing in consideration of the influence of the temperature rise of the electrostatic sensor electrode 121 accompanying the operation of the slider 111.

[0040] <Transition from the On_LowTemperature state to On_NormalTemperature along 2b) NormalTemperature> When the in-vehicle temperature detected by the temperature sensor 140 becomes higher than the temperature threshold value in the On_LowTemperature state, the electrostatic input device 100 transitions to the On_NormalTemperature state along 2b) NormalTemperature. Since the temperature has returned from a low state to a high state, the electrostatic input device 100 transitions to the On_NormalTemperature state.

[0041] <Transition from the On_LowTemperature state to Monitoring along 5) Decrease> In the On_LowTemperature state, when the measured value of the electrostatic sensor electrode 121 significantly decreases, the state of the electrostatic input device 100 transitions to the Monitoring state along 5) Decrease. Since Monitoring is due to the significant decrease in the measured value of the electrostatic sensor electrode 121, it is a state that starts monitoring whether the proximity state is on (On) or off (Off). As described later, the Monitoring state has two states: Off_Monitoring and On_Monitoring. Both transition from On_LowTemperature, which indicates being on at low temperatures. Therefore, due to temperature changes, the reference value may change significantly. Thus, there is a possibility that the control unit 131 may misjudge On / Off. In the present invention, in the two Monitoring states, the On / Off and the necessity of updating the reference value are judged based on criteria different from the well-known criteria (the magnitude relationship between the measured value and the threshold value). Then, the On / Off is accurately judged, and the necessity of updating the reference value is appropriately and promptly judged.

[0042] <The state of Monitoring transitions to Off_Monitoring along 3) Off> In the Monitoring state, when the maximum value among the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is lower than the off threshold value, the state of the electrostatic input device 100 transitions to the Off_Monitoring state along 3) Off. The Off_Monitoring state is an example of a non-proximity monitoring state. Off_Monitoring is a state that monitors whether the proximity state is truly off although the measured value of the electrostatic sensor electrode 121 has significantly decreased and the maximum differential value ΔCapacity is lower than the off threshold value.

[0043] <The state of Monitoring transitions to On_Monitoring along 6) NotOff> In the Monitoring state, if the maximum value among the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is higher than the off threshold value, the state of the electrostatic input device 100 transitions to the On_Monitoring state along 6) NotOff. The On_Monitoring state is a proximity monitoring state. In On_Monitoring, although the measured values of the electrostatic sensor electrodes 121 have decreased significantly, since the maximum differential value ΔCapacity is higher than the off threshold value, it is a state for monitoring whether the proximity state is truly On.

[0044] <Transition from the Off_Monitoring state to the On_LowTemperature state along 7) Increase> In the Off_Monitoring state, if the increase in the total value of the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is large, it is considered that the fingertip FT that has been separated from the operation surface 105A has approached again. For this reason, the state of the electrostatic input device 100 transitions to the On_LowTemperature state along 7) Increase. This is to reprocess in the On_LowTemperature state. In the Off_Monitoring state, it is highly likely that the fingertip FT has left the operation surface 105A. However, there is a slight possibility that the fingertip FT has not left the operation surface 105A. Therefore, when the control unit 131 updates the reference value, there is a risk that the reference value will be set to an incorrect value. If the reference value is incorrect, the control unit 131 cannot correctly determine the proximity state / non - proximity state (On / Off). By using the increase amount of the total value of the five differential values ΔCapacity, it is possible to accurately determine that the proximity state (On) has been reached regardless of the accuracy of the reference value.

[0045] <Transition from the Off_Monitoring state to the Off state along 9) Tiny> In the Off_Monitoring state, when the sum of the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is at a minimum, it is considered that the fingertip FT has left the operation surface 105A. Therefore, the state of the electrostatic input device 100 transitions to Off along 9) Tiny. When the control unit 131 confirms that the reference value has hardly changed, it transitions from "Off_Monitoring" that performs monitoring specific to the present invention to "Off" that performs the same processing as the well-known technology.

[0046] <Transition from the Off_Monitoring state to BaseReset along 10) Calibrate1> In the Off_Monitoring state, when the fluctuation of the sum of the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is small and the duration of the state where the fluctuation of the sum of the differential values ΔCapacity is small has elapsed the first update time for reference value update, it is considered that the fingertip FT has left the operation surface 105A. Since the condition of 9) Tiny is not satisfied, it is considered that the reference value has changed due to the influence of temperature or the like. Therefore, the state of the electrostatic input device 100 transitions to BaseReset along 10) Calibrate1. Based on the measured values of the electrostatic sensor electrodes 121, the reference value stored in the memory 132 is updated. When the reference value is updated, the state of the electrostatic input device 100 transitions to the Off state. Off_Monitoring is a state where the differential value has decreased. When the state where the differential value has decreased and the fluctuation of the differential value is small continues, the possibility that the fingertip FT has left the operation surface 105A is very high. Conversely, if the fingertip FT is not moved while being in contact with the operation surface 105A, the reference value is not updated. Since it is possible to accurately determine that the fingertip FT has left the operation surface 105A, the first update time can be shortened and the reference value can be quickly updated to the correct value.

[0047] <Transition from the On_Monitoring state to On_LowTemperature along 7) Increase> In the On_Monitoring state, even if the variation in the total value of the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is small, if there is a variation in which the total of Δcapacity increases due to an operation such as the finger approaching again, it transitions to the On_LowTemperature state along 7)Increase. That is, it returns to the process in the state where the fingertip FT is surely touching the operation surface 105A.

[0048] <Transition from the On_Monitoring state to On_LowTemperature along 8)Change> In the On_Monitoring state, if the variation in the total value of the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 is large, it is considered that the fingertip FT is being moved on the operation surface 105A. When the fingertip FT is moved on the operation surface 105A, the facing area between the electrostatic sensor electrode 12I and the fingertip FT changes, and the total value of the five differential values ΔCapacity varies. Therefore, the state of the electrostatic input device 100 transitions to the On_LowTemperature state along 8)Change. That is, it returns to the process in the state where the fingertip FT is surely touching the operation surface 105A.

[0049] <Transition from the On_Monitoring state to Off_Monitoring along 3c)Off> In the On_Monitoring state, when the maximum value MaxΔCapacity(i) among the five differential values ΔCapacity obtained from the five electrostatic sensor electrodes 121 becomes smaller than the off threshold ThOff, it is considered that the proximity state has become off (Off). Therefore, the state of the electrostatic input device 100 transitions to Off_Monitoring along 3c)Off.

[0050] <Transition from the On_Monitoring state to BaseReset along 11)Calibrate2> In the On_Monitoring state, if the total value of the five difference values ​​ΔCapacity obtained from the five electrostatic sensor electrodes 121 fluctuates little, and the duration of this small fluctuation in the total difference values ​​ΔCapacity exceeds the second update time for updating the reference value, it is considered that the reference value fluctuates and the proximity state is on, even though the fingertip FT is separated from the operation surface 105A. Therefore, the reference value is updated, and the proximity state is turned off. In other words, the state of the electrostatic input device 100 transitions from BaseReset to off according to 11) Calibrate2. Measurement values ​​of the electrostatic sensor electrodes 121 are acquired, and the reference value stored in the memory 132 is updated. Even if the fingertip FT is stopped while still in contact with the operation surface 105A, the total value of the difference values ​​ΔCapacity fluctuates little. For this reason, the second update time is set to a long time to prevent the reference value from being updated to an incorrect value. However, the On_Monitoring state also indicates a state in which the difference value has decreased. If the difference value continues to decrease and the fluctuation of the difference value remains small, there is a high possibility that the fingertip FT is separated from the operation surface 105A. In other words, it can be accurately determined that the fingertip FT is separated from the operation surface 105A.

[0051] <Flowchart> 4A to 4D are flowcharts showing an example of processing executed by the control unit 131 of the electrostatic input device 100. FIG.

[0052] When the control unit 131 starts processing (Start), it stores default values ​​in each variable (step S1). Specifically, it assigns Off to the proximity status Status and 0 to MonitoringTime. "=" in the flowchart means that the value on the right side is assigned to the variable on the left side. In other words, it means an operation of assigning a value to a variable. The proximity status Status is a variable that represents On or Off. In other words, if the indicator FT is in proximity to the electrostatic sensor electrode 121, the control unit 131 assigns On to the proximity status Status. On the other hand, if the indicator FT is not in proximity to the electrostatic sensor electrode 121, the control unit 131 assigns Off to the proximity status Status. MonitoringTime is a variable that represents the time that the Off_Monitoring state shown in FIG. 3 continues.

[0053] The control unit 131 determines whether the maximum value MaxΔCapacity(i) of the multiple difference values ​​ΔCapacity(i) is greater than the on threshold value ThOn (step S2). i represents the i-th difference value ΔCapacity. If the number of electrostatic sensor electrodes 121 is five, i can take on values ​​from 1 to 5. The on threshold value ThOn is an example of a proximity threshold value.

[0054] If the control unit 131 determines that the maximum value MaxΔCapacity(i) is greater than the on threshold ThOn (S2: Yes), it sets the proximity status Status to On (step S3).

[0055] If the control unit 131 determines in step S2 that the maximum value MaxΔCapacity(i) is not greater than the on threshold ThOn (S2: No), it performs the process of step S2 again.

[0056] The control unit 131 determines whether the vehicle interior temperature (Temperature) detected by the temperature sensor 140 is lower than the temperature threshold value (ThTemp) (step S4). This is to determine whether the temperature of the electrostatic sensor electrode 121 has dropped. If the temperature sensor 140 is not provided, the temperature may be determined based on a reference value. As the temperature drops, the sensitivity of the electrostatic sensor decreases, and the reference value decreases. Therefore, if the reference value is lower than a predetermined value, the control unit 131 may branch to S4: Yes, and if the reference value is higher than the predetermined value, the control unit 131 may branch to S4: No.

[0057] When the control unit 131 determines that the vehicle interior temperature (Temperature) detected by the temperature sensor 140 is not lower than the temperature threshold (ThTemp) (S4: No), it determines whether the maximum value MaxΔCapacity(i) is smaller than the off threshold ThOff (step S5). This is to determine whether the fingertip FT has been removed from the operation surface 105A when the vehicle interior temperature is not low. The off threshold ThOff is a non-proximity threshold.

[0058] If the control unit 131 determines that the maximum value MaxΔCapacity(i) is not smaller than the OFF threshold value ThOff (S5: No), it repeats the process of step S5, and if it determines that the maximum value MaxΔCapacity(i) is smaller than the OFF threshold value ThOff (S5: Yes), it sets the proximity status Status to Off (step S6). That is, it performs processing of Status=Off. The control unit 131 updates the reference value by a well-known method (not shown).

[0059] After completing the process of step S6, the control unit 131 returns the flow to step S2 to prepare for the next operation.

[0060] When the control unit 131 determines in step S4 that the vehicle interior temperature (Temperature) detected by the temperature sensor 140 is lower than the temperature threshold value (ThTemp) (S4: Yes), it stores the total difference value ΣΔCapacity(i), which is the sum of the most recent five difference values ​​ΔCapacity(i), in the memory 132 as the low-temperature total difference value (EnterLowTemperatureSum) when the vehicle interior temperature drops (step S7). That is, EnterLowTemperatureSum=ΣΔCapacity(i).

[0061] The control unit 131 determines whether the total difference value ΣΔCapacity(i) is greater than the maximum value (MaxCapacitySum) of the total difference values ​​ΣΔCapacity(i) up to that point (step S8). That is, the control unit 131 determines whether MaxCapacitySum<ΣΔCapacity(i).

[0062] If the control unit 131 determines that the total difference value ΣΔCapacity(i) is greater than the maximum value (MaxCapacitySum) (S8: Yes), it assigns the total difference value ΣΔCapacity(i) to the maximum value (MaxCapacitySum) of the total difference values ​​ΣΔCapacity(i) up to that point (step S9). That is, it performs the process of MaxCapacitySum=ΣΔCapacity(i). After completing the process of step S9, the control unit 131 advances the flow to step S10.

[0063] If the control unit 131 determines in step S8 that the total differential value ΣΔCapacity(i) is not greater than the maximum value (MaxCapacitySum) (S8: No), it skips the process of step S9 and advances the flow to step S10.

[0064] In step S8, the control unit 131 may determine whether each of the five difference values ​​ΔCapacity(i) is greater than the maximum value (MaxCapacitySum) of the total difference values ​​ΣΔCapacity(i) up to that point in time, instead of determining whether the total difference value ΣΔCapacity(i) is greater than the maximum value (MaxCapacitySum). If at least one of the five difference values ​​ΔCapacity(i) is greater than the maximum value (MaxCapacitySum), the control unit 131 may perform the process of step S9, and if all five difference values ​​ΔCapacity(i) are smaller than the maximum value (MaxCapacitySum), the control unit 131 may proceed to step S10 without performing the process of step S9.

[0065] In this way, the five difference values ​​ΔCapacity(i) are compared with the comparison target value instead of the total difference value ΣΔCapacity(i), which also applies to processing that uses the total difference value ΣΔCapacity(i), which will be described later.

[0066] The control unit 131 determines whether the vehicle interior temperature (Temperature) detected by the temperature sensor 140 is lower than the temperature threshold (ThTemp) (step S10). This is to determine whether the temperature of the electrostatic sensor electrode 121 has decreased. If the temperature sensor 140 is not used, the determination in step S10 is omitted.

[0067] When the control unit 131 determines that the vehicle interior temperature (Temperature) detected by the temperature sensor 140 is not lower than the temperature threshold (ThTemp) (S10: No), the control unit 131 advances the flow to step S5. This is to determine whether the fingertip FT has been removed from the operation surface 105A when the vehicle interior temperature is not low.

[0068] When the control unit 131 determines that the in-vehicle temperature (Temperature) detected by the temperature sensor 140 is lower than the temperature threshold value (ThTemp) (S10: Yes), it determines whether the value obtained by subtracting the latest total difference value ΣΔCapacity(i) from the maximum value (MaxCapacitySum) of the total difference value ΣΔCapacity(i) up to that point is greater than half of the low-temperature total difference value (EnterLowTemperatureSum) (step S11). That is, the control unit 131 determines whether EnterLowTemperatureSum / 2 < MaxCapacitySum - ΣΔCapacity(i) holds. Step S11 is a process for determining whether the latest total difference value ΣΔCapacity(i) has decreased. MaxCapacitySum - ΣΔCapacity(i) is an example of the second difference value. The value of half of the low-temperature total difference value (EnterLowTemperatureSum / 2) is an example of the decrease threshold value. The constant (1 / 2) multiplied by the low-temperature total difference value is an example of the first constant. The first constant is not limited to 1 / 2 and may be an appropriate value.

[0069] If the latest total difference value ΣΔCapacity(i) has decreased, since the fingertip FT may be away from the operation surface 105A, the process of step S11 is performed to monitor whether it is necessary to update the reference value.

[0070] When the control unit 131 determines that EnterLowTemperatureSum / 2 < MaxCapacitySum - ΣΔCapacity(i) does not hold (S11: No), it returns the flow to step S8. This is because the latest total difference value ΣΔCapacity(i) is not low, so it is for comparison with the maximum value (MaxCapacitySum).

[0071] When the control unit 131 determines in step S11 that EnterLowTemperatureSum / 2 < MaxCapacitySum - ΣΔCapacity(i) holds (S11: Yes), it stores the latest ΣΔCapacity(i) in the memory 132 as the total difference value (EnterMonitoringSum) when starting Monitoring (step S12). That is, the control unit 131 substitutes ΣΔCapacity(i) into EnterMonitoringSum.

[0072] The control unit 131 determines whether the maximum value MaxΔCapacity(i) among the five latest ΣΔCapacity(i) is smaller than the off threshold ThOff (step S13). That is, the control unit 131 determines whether MaxΔCapacity(i) < ThOff holds. This is for checking the proximity state.

[0073] When the control unit 131 determines that the maximum value MaxΔCapacity(i) is smaller than the off threshold ThOff (S13: Yes), it sets the proximity state to off (step S14). That is, it performs the process of Status = Off.

[0074] Also, when the control unit 131 determines in step S13 that the maximum value MaxΔCapacity(i) is not smaller than the off threshold ThOff (S13: No), it advances the flow to step S23. Since the proximity state is on and the maximum value MaxΔCapacity(i) is relatively large, it proceeds to the process of determining whether to update the reference value (steps S23 and subsequent). The processes after step S23 will be described later.

[0075] When the control unit 131 finishes the process of step S14, it determines whether the value obtained by subtracting the latest total difference value ΣΔCapacity(i) from the maximum value (MaxCapacitySum) of the total difference value ΣΔCapacity(i) up to that point is less than 2 / 5 of the low-temperature total difference value (EnterLowTemperatureSum) (step S15). That is, the control unit 131 determines whether EnterLowTemperatureSum×2 / 5 > MaxCapacitySum - ΣΔCapacity(i) holds. Step S15 is a process for determining whether the latest total difference value ΣΔCapacity(i) has increased significantly. When the total difference value ΣΔCapacity(i) increases significantly, the control unit 131 determines that the fingertip FT has touched the operation surface 105A. The constant (2 / 5) multiplied by the low-temperature total difference value is an example of the second constant. The second constant is not limited to 2 / 5 and may be an appropriate value.

[0076] When the control unit 131 determines that EnterLowTemperatureSum×2 / 5 > MaxCapacitySum - ΣΔCapacity(i) does not hold (S15: No), it determines whether the latest total difference value ΣΔCapacity(i) is less than the extremely small fluctuation threshold ThTiny (step S16). That is, the control unit 131 determines whether ΣΔCapacity(i) < ThTiny holds.

[0077] When the control unit 131 determines that the latest total difference value ΣΔCapacity(i) is less than the extremely small fluctuation threshold ThTiny (S16: Yes), it performs the process of MonitoringTime = 0 (step S17). That is, the control unit 131 substitutes 0 into MonitoringTime. MonitoringTime represents the time during which the Off_Monitoring state (see FIG. 3) continues, so when MonitoringTime becomes zero, it corresponds to ending the Off_Monitoring state (see FIG. 3).

[0078] When the control unit 131 finishes the process of step S17, it returns the flow to step S2. Returning to step S2 corresponds to transitioning to the off state according to 9) Tiny. Step S2 determines whether the proximity state is on.

[0079] When the flow proceeds from step S16 to step S17, the proximity state is off and the latest total difference value ΣΔCapacity(i) has minimal fluctuation, so it is considered that no touch has actually occurred. In this state, the reference value stored in memory 132 is considered to be an appropriate value, so the proximity state is turned off without updating the reference value.

[0080] If the control unit 131 determines in step S16 that the latest total difference value ΣΔCapacity(i) is not smaller than the minimal fluctuation threshold ThTiny (S16: No), it increments MonitoringTime (step S18). That is, it performs the process of MonitoringTime=MonitoringTime+1.

[0081] The control unit 131 determines whether MonitoringTime has passed the first update time ThCalibrateTime1 (step S19). That is, the control unit 131 determines whether MonitoringTime>ThCalibrateTime1 is true. The determination in step S19 is made in a state where it is considered that the fingertip FT is not touching the operation surface 105A, and therefore the first update time ThCalibrateTime1 is shorter than the second update time ThCalibrateTime2, which will be described later. The first update time ThCalibrateTime1 and the second update time ThCalibrateTime2 are examples of predetermined times.

[0082] If the control unit 131 determines that MonitoringTime has not passed the first update time ThCalibrateTime1 (S19: No), the control unit 131 returns the flow to step S15. By repeating the loop of steps S15, S16, S18, S19, and returning to step S15, the value of MonitoringTime increases.

[0083] If the control unit 131 determines in step S19 that MonitoringTime has passed the first update time ThCalibrateTime1 (S19: Yes), the control unit 131 sets MonitoringTime to zero (step S20). That is, the control unit 131 performs a process of MonitoringTime=0 and ends the Off_Monitoring state.

[0084] The control unit 131 updates the reference value (step S21). The control unit 131 sets the reference value (Base) to the value ΣΔCapacity(i) / i obtained by dividing the total difference value ΣΔCapacity(i), which is the sum of the latest five difference values ​​ΔCapacity(i), by 5, which is the number of electrostatic sensor electrodes 121. That is, the processing of Base=(ΣΔCapacity(i)) / i is performed. That is, ΣΔCapacity(i)) / i is stored in the memory 132 as a new reference value. This processing corresponds to transitioning to the BaseReset state in accordance with 10) Calibrate1.

[0085] In this way, when the vehicle interior temperature detected by the temperature sensor 140 becomes lower than the temperature threshold value ThTemp and no touch operation is being performed, the reference value is updated to a value corresponding to the vehicle interior temperature.

[0086] When the control unit 131 finishes the processing of step S20, it returns the flow to step S2. Returning to step S2 corresponds to transitioning to the Off state. When returning to step S2, the control unit 131 determines whether the proximity state is On. The updated reference value is used to determine the proximity state.

[0087] When the flow proceeds from step S16 to step S17, the proximity state is off and the latest total difference value ΣΔCapacity(i) is extremely small, so it is considered that a hand is not in proximity to the electrostatic sensor 120. This state means that the difference between each difference value ΔCapacity(i) and the reference value (Base value) is small. Because the reference value stored in memory 132 is an appropriate value, the proximity state is turned off without updating the reference value.

[0088] If the control unit 131 determines in step S15 that EnterLowTemperatureSum×2 / 5>MaxCapacitySum−ΣΔCapacity(i) is true (S15: Yes), it sets MonitoringTime to zero (step S22). That is, the control unit 131 sets MonitoringTime=0. The determination in step S15 is Yes when the value of MaxCapacitySum−ΣΔCapacity(i) becomes smaller due to an increase in ΣΔCapacity(i).

[0089] "Completing the process of step S22 and returning the flow to step S8" corresponds to transitioning from the Off_Monitoring state to the On_LowTemperature state along 7) Increase. Since the Off_Monitoring state is no longer present, the control unit 131 sets MonitoringTime to zero (step S22). After completing the process of step S22, the control unit 131 returns the flow to step S8 and determines whether the latest total differential value ΣΔCapacity(i) is greater than the maximum value (MaxCapacitySum) of the total differential values ​​ΣΔCapacity(i) up to that point.

[0090] In step S13, when the control unit 131 determines that the maximum value MaxΔCapacity(i) is not less than the off threshold ThOff (S13: No), it determines whether the value obtained by subtracting the latest total difference value ΣΔCapacity(i) from the maximum value (MaxCapacitySum) of the total difference value ΣΔCapacity(i) up to that point is less than 2 / 5 of the low-temperature total difference value (EnterLowTemperatureSum) (step S23). The process of step S23 is the same as the process of step S15, and the control unit 131 determines whether EnterLowTemperatureSum×2 / 5 > MaxCapacitySum - ΣΔCapacity(i) holds. Step S23 is a process for determining whether the latest total difference value ΣΔCapacity(i) has increased significantly. When the total difference value ΣΔCapacity(i) increases significantly, the control unit 131 determines that the fingertip FT is surely touching the operation surface 105A.

[0091] When the control unit 131 determines that EnterLowTemperatureSum×2 / 5 > MaxCapacitySum - ΣΔCapacity(i) does not hold (S23: No), it determines whether ΣΔCapacity(i) - EnterMonitoringSum > ThChange1 or ΣΔCapacity(i) - EnterMonitoringSum < ThChange2 holds (step S24).

[0092] ΣΔCapacity(i) - EnterMonitoringSum > ThChange1 is a process of determining whether the value obtained by subtracting the total differential value EnterMonitoringSum at the start of monitoring from the total differential value ΣΔCapacity(i) is greater than the positive first change constant ThChange1 when the total differential value ΣΔCapacity(i) increases. When the fingertip FT is moved on the operation surface 105A, the facing area between the fingertip FT and the electrostatic sensor electrode 121 changes, and the total differential value ΣΔCapacity(i) changes. When the total differential value ΣΔCapacity(i) changes, the control unit 131 determines that the fingertip FT is surely touching the operation surface 105A.

[0093] ΣΔCapacity(i) - EnterMonitoringSum < ThChange2 is a process of determining whether the value obtained by subtracting the total differential value EnterMonitoringSum at the start of monitoring from the total differential value ΣΔCapacity(i) is less than the negative second change constant ThChange2 when the total differential value ΣΔCapacity(i) decreases. When the fingertip FT is moved on the operation surface 105A, the facing area between the fingertip FT and the electrostatic sensor electrode 121 changes, and the total differential value ΣΔCapacity(i) changes. In the state of On_Monitoring, when the total differential value ΣΔCapacity(i) changes, the control unit 131 determines that the fingertip FT is surely touching the operation surface 105A.

[0094] When the control unit 131 determines that neither ΣΔCapacity(i) - EnterMonitoringSum > ThChange1 nor ΣΔCapacity(i) - EnterMonitoringSum < ThChange2 holds (S24: No), it determines whether the maximum value MaxΔCapacity(i) among the five latest ΣΔCapacity(i) values is less than the off-threshold ThOff (step S25). That is, the control unit 131 determines whether MaxΔCapacity(i) < ThOff holds. This is to confirm the proximity state.

[0095] If the control unit 131 determines that the maximum value MaxΔCapacity(i) is not smaller than the OFF threshold ThOff (S25: No), it increments MonitoringTime (step S26). That is, it performs the process of MonitoringTime=MonitoringTime+1.

[0096] The control unit 131 determines whether MonitoringTime has passed the second update time ThCalibrateTime2 (step S27). That is, the control unit 131 determines whether MonitoringTime>ThCalibrateTime2 is true. The process of step S27 is performed in a state where the fingertip FT may be touching the operation surface 105A, and therefore the second update time ThCalibrateTime2 is longer than the first update time ThCalibrateTime1 used in step S19.

[0097] If the control unit 131 determines that the MonitoringTime has not passed the second update time ThCalibrateTime2 (S27: No), the control unit 131 returns the flow to step S23.

[0098] When the control unit 131 determines in step S27 that MonitoringTime has passed the second update time ThCalibrateTime2 (S27: Yes), it updates the reference value (step S28). The control unit 131 sets the reference value (Base) to the value ΣΔCapacity(i) / i obtained by dividing the total difference value ΣΔCapacity(i), which is the sum of the latest five difference values ​​ΔCapacity(i), by 5, which is the number of electrostatic sensor electrodes 121. That is, the control unit 131 performs the process of Base=(ΣΔCapacity(i)) / i. ΣΔCapacity(i) / i is stored in the memory 132 as a new reference value.

[0099] The control unit 131 sets the proximity state to OFF (step S29), that is, assigns Off to Status.

[0100] In this way, when the in-vehicle temperature detected by the temperature sensor 140 becomes lower than the temperature threshold ThTemp and no touch operation is being performed, it is updated to a reference value corresponding to the in-vehicle temperature.

[0101] The flow proceeds from step S28 to step S29, which corresponds to the case of transitioning from the Off state to the BaseReset state.

[0102] The control unit 131 sets MonitoringTime to zero (step S30). That is, the control unit 131 sets MonitoringTime = 0. When the flow proceeds from step S28 through step S29 to step S30, it corresponds to the case of going from 11) Calibrate2 in FIG. 3 through BaseReset to Off.

[0103] Also, when the control unit 131 determines in step S5 that the maximum value MaxΔCapacity(i) is smaller than the off threshold ThOff (S25: Yes), it sets MonitoringTime to zero (step S30). That is, the control unit 131 sets MonitoringTime = 0.

[0104] Also, when the control unit 131 determines in step S23 that EnterLowTemperatureSum×2 / 5 > MaxCapacitySum - ΣΔCapacity(i) holds (S23: YEs), it substitutes zero into MonitoringTime (step S32). That is, the control unit 131 performs the process of MonitoringTime = 0.

[0105] Also, when the control unit 131 determines in step S24 that ΣΔCapacity(i) - EnterMonitoringSum > ThChange1 or ΣΔCapacity(i) - EnterMonitoringSum < ThChange2 holds (S24: Yes), it substitutes zero into MonitoringTime (step S32). That is, the control unit 131 performs the process of MonitoringTime = 0.

[0106] After completing the process of step S32, the flow returns to step S8. That is, if the sum of the difference values ​​ΣΔCapacity(i) fluctuates significantly or increases, the state transitions to On_LowTemperature. After returning to step S8, it is determined whether the latest total difference value ΣΔCapacity(i) is greater than the maximum value (MaxCapacitySum) of the total difference values ​​ΣΔCapacity(i) up to that point.

[0107] <First Modification> FIG. 5 is a diagram showing an example of the configuration of an electrostatic input device 100M1 according to a first modified example of the embodiment. The electrostatic input device 100M1 includes an electrostatic sensor 120M1 instead of the electrostatic sensor 120 of the electrostatic input device 100 shown in FIG. 2. The electrostatic sensor 120M1 has a plurality of electrostatic sensor electrodes 121X extending in the X direction and a plurality of electrostatic sensor electrodes 121Y extending in the Y direction. The measurement circuit 125A sequentially selects the plurality of electrostatic sensor electrodes 121X and the plurality of electrostatic sensor electrodes 121Y and measures the capacitance at the intersections. Such an electrostatic sensor 120M1 can detect the contact position of a finger.

[0108] <Second Modification> 6 is a diagram showing an example of the configuration of an electrostatic input device 100M2 according to a second modified example of the embodiment. The electrostatic input device 100M2 includes an electrostatic sensor 120M2 instead of the electrostatic sensor 120 of the electrostatic input device 100 shown in FIG. 2, and does not include a display 110. The electrostatic sensor 120M2 has only one electrostatic sensor electrode 121. The measurement circuit 125A measures the capacitance of the electrostatic sensor electrode 121. The present invention is also applicable to such a single electrostatic sensor 120M2.

[0109] <Effects> The electrostatic input device 100 includes a plurality of electrostatic sensor electrodes 121, a measurement circuit 125A that outputs a measurement value based on the electrostatic capacitance between each of the plurality of electrostatic sensor electrodes 121 and a pointer, a control unit 131 that determines whether the pointer is in proximity to the plurality of electrostatic sensor electrodes 121 based on the measurement value output by the measurement circuit 125A, and a memory 132 that stores a measurement value when the pointer is not in proximity to the plurality of electrostatic sensor electrodes 121 as a reference value (Base). The control unit 131 determines whether the proximity state is present based on a difference value ΔCapacity obtained by subtracting the reference value from the measurement value, calculates a total difference value ΣΔCapacity(i) by summing the plurality of difference values ​​ΔCapacity of the plurality of electrostatic sensor electrodes 121, and, in the proximity state, if the amount of change in the total difference value ΣΔCapacity(i) is smaller than a predetermined value after the total difference value ΣΔCapacity(i) has decreased and continues to be smaller than a predetermined value for a predetermined time or more (S27: Yes), updates the reference value (S21, S28). Therefore, even if the fingertip FT is away from the operation surface 105A, if a temperature change in the electrostatic sensor electrode 121 erroneously determines that the fingertip FT is in proximity, the reference value is promptly updated. Conventionally, the reference value is updated when the amount of change in the total differential value ΣΔCapacity(i) remains small for a long period of time. However, if the reference value is updated only when the amount of change in ΣΔCapacity(i) remains small, there is a possibility that the reference value will be updated while the finger remains stationary and touching the sensor surface. This invention combines two conditions: "the total differential value ΣΔCapacity(i) has decreased" and "the amount of change in the total differential value ΣΔCapacity(i) remains smaller than a predetermined value for a predetermined period of time or more." This prevents the reference value from being updated while the finger remains stationary and touching the sensor surface. In other words, the reference value can be promptly updated while preventing erroneous operation.

[0110] Therefore, it is possible to provide the electrostatic input device 100 that can prevent the reference value from being updated to the measurement value when the finger is in contact with the sensor surface, even if the finger is stopped while in contact with the sensor surface.

[0111] Furthermore, the control unit 131 may store the total difference value ΣΔCapacity(i) when the total difference value ΣΔCapacity(i) is highest in the memory 132 as a maximum total difference value MaxCapacitySum (S8, S9), and determine that the total difference value ΣΔCapacity(i) has decreased (S11: Yes) when a second difference value MaxCapacitySum-ΣΔCapacity(i) obtained by subtracting the latest total difference value ΣΔCapacity(i) from the maximum total difference value MaxCapacitySum is greater than a decrease threshold EnterLowTemperatureSum / 2. Even when the proximity state / non-proximity state cannot be accurately determined due to a temperature change in the electrostatic sensor 120, it is possible to detect the possibility that a finger has left the operation surface 105A.

[0112] Furthermore, when the ambient temperature of the multiple electrostatic sensor electrodes 121 is lower than the temperature threshold (ThTemp) (S4), the control unit 131 stores the total difference value ΣΔCapacity(i) at the time of determining that the proximity state is present (S2) as a low-temperature total difference value EnterLowTemperatureSum in the memory 132 (S7), and the decrease threshold EnterLowTemperatureSum / 2 may be a first constant (½) multiplied by the low-temperature total difference value ΣΔCapacity(i). By using the relative value of the low-temperature total difference value EnterLowTemperatureSum, it is possible to appropriately determine a decrease in the latest total difference value ΣΔCapacity(i) regardless of the temperature.

[0113] The control unit 131 may determine that the state is in proximity when any one of the plurality of difference values ​​ΔCapacity is greater than a proximity threshold (ThOn) (S2), and determine that the state is in non-proximity when any one of the plurality of difference values ​​ΔCapacity is less than a non-proximity threshold (ThOff) (S13). In the proximity state, if it determines that the total difference value ΣΔCapacity(i) has decreased (S11: Yes) and then if any one of the plurality of difference values ​​ΔCapacity exceeds the non-proximity threshold (S13: No), it may transition to a proximity monitoring state (On_Monitoring: S23). In the proximity state, if the increase in the total difference value ΣΔCapacity(i) is greater than a predetermined value, it may determine that the state is in proximity (On) (S15: Yes). If the total difference value ΣΔCapacity(i) increases, the fingertip FT is clearly touching the operation surface 105A, and by determining that the state is in proximity, the proximity state can be correctly determined.

[0114] Furthermore, the control unit 131 may determine that the total difference value ΣΔCapacity(i) has increased when the second difference value MaxCapacitySum-ΣΔCapacity(i) becomes smaller than an increase threshold. By using the second difference value MaxCapacitySum-ΣΔCapacity(i) between the maximum total difference value MaxCapacitySum when the fingertip FT is in contact with the operation surface 105A over the largest area and the latest total difference value ΣΔCapacity(i), it is possible to accurately detect the amount of increase in the latest total difference value ΣΔCapacity(i).

[0115] The increase threshold may be a second constant multiple (2 / 5) of the low-temperature total differential value ΣΔCapacity(i). By using the relative value of the low-temperature total differential value ΣΔCapacity(i), it is possible to appropriately determine whether the fingertip FT is approaching the operation surface 105A regardless of the temperature.

[0116] Furthermore, the control unit 131 may determine that the state is in proximity when any one of the plurality of difference values ​​ΔCapacity is greater than a proximity threshold (ThOn) (S2), and after determining that the total difference value ΣΔCapacity(i) has decreased in the proximity state (S11: Yes), if the plurality of difference values ​​ΔCapacity are less than a non-proximity threshold (S13: Yes), transition to a non-proximity monitoring state (Off Monitoring), and transition to the proximity state if the total difference value ΣΔCapacity(i) changes in the proximity monitoring state or non-proximity monitoring state. By determining that the fingertip FT is in proximity to the electrostatic sensor 120 when the total difference value ΣΔCapacity(i) has changed, it is possible to appropriately determine whether the fingertip FT is in contact with the operation surface 105A.

[0117] Furthermore, the control unit 131 may transition to the proximity state when the difference value obtained by subtracting the low-temperature total difference value ΣΔCapacity(i) from the total difference value ΣΔCapacity(i) is greater than a positive first change constant, or when the difference value obtained by subtracting the low-temperature total difference value ΣΔCapacity(i) from the total difference value ΣΔCapacity(i) is smaller than a negative second change constant. By comparing the relative value of the low-temperature total difference value ΣΔCapacity(i) with a constant, it is possible to appropriately determine whether the fingertip FT is in proximity to the operation surface 105A.

[0118] Furthermore, the control unit 131 updates the reference value when the non-proximity monitoring state continues longer than the first update time, or when the proximity monitoring state continues longer than the second update time, and the first update time may be shorter than the second update time. By using different thresholds (first update time and second update time) for the non-proximity monitoring state and the proximity monitoring state to make a judgment, it is possible to correctly and quickly determine the timing for updating the reference value.

[0119] Furthermore, if the total difference value ΣΔCapacity(i) is smaller than a predetermined extremely small minimum threshold (ThTiny) in the non-proximity monitoring state, the control unit 131 may transition to the non-proximity state without updating the reference value. Therefore, the reference value can be updated appropriately.

[0120] The device may further include a temperature sensor that measures the ambient temperature of the plurality of electrostatic sensor electrodes 121, and the control unit 131 may perform the following processes when the ambient temperature of the plurality of electrostatic sensor electrodes 121 is lower than a temperature threshold (ThTemp) (S4): determining whether a proximity state exists, calculating the total difference value ΣΔCapacity(i), and updating the reference value. If a fingertip starts to touch the operation surface 105A at low temperatures, the temperature of the electrostatic sensor 120 may rise rapidly due to heating during operation. Furthermore, if operation with a fingertip continues at low temperatures, the temperature of the electrostatic sensor 120 may rise rapidly due to body heat. By limiting these processes to when a fingertip starts to touch the operation surface 105A at low temperatures, the timing for updating the reference value can be appropriate.

[0121] Furthermore, the control unit 131 may perform the above-described process only when the temperature when the proximity state is established is lower than a predetermined value (S4). By performing the above-described process when the temperature inside the vehicle is low when the proximity state is established, it is possible to provide the electrostatic input device 100 that can prevent an erroneous determination that a proximity operation is not being performed even if a finger is stopped while in contact with the sensor surface, and can prevent updating to an erroneous reference value.

[0122] The electrostatic input device 100 includes an electrostatic sensor electrode 121, a measurement circuit 125A that outputs a measurement value based on the capacitance between the electrostatic sensor electrode 121 and a pointer, a control unit 131 that determines whether the pointer is in proximity to the electrostatic sensor electrode 121 based on the measurement value output by the measurement circuit 125A, and a memory 132 that stores a measurement value when the pointer is not in proximity to the electrostatic sensor electrode 121 as a reference value (Base). The control unit 131 determines whether the electrostatic sensor electrode 121 is in proximity based on a difference value ΔCapacity obtained by subtracting the reference value from the measurement value. In the proximity state, if the amount of change in the difference value ΔCapacity is smaller than a predetermined value and continues for a predetermined time or more after the difference value ΔCapacity decreases (S27: Yes), the control unit 131 updates the reference value. Therefore, if the proximity state is erroneously determined due to a temperature change in the electrostatic sensor electrode 121 even though the fingertip FT is away from the operation surface 105A, the reference value is promptly updated.

[0123] Therefore, even if the sensitivity of the electrostatic sensor electrode 121 changes due to a temperature change or the like, the reference value can be updated quickly. Moreover, even if the finger is stopped while in contact with the operation surface, it is possible to provide the electrostatic input device 100 that can prevent the reference value from being updated to an incorrect value by erroneously determining that the finger has been removed from the operation surface.

[0124] While the electrostatic input device according to the exemplary embodiment of the present disclosure has been described above, 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. [Explanation of symbols]

[0125] 100 electrostatic input device 101 Case 105 Top Panel 105A Operation surface 110 Display 111 Slider 111A Frame 120 Electrostatic Sensor 121 Electrostatic sensor electrode 125A measuring circuit 125B Image display circuit 130 Control device 131 Control Unit 132 memory 140 Temperature Sensor

Claims

1. Multiple electrostatic sensor electrodes, A measurement circuit that outputs a measurement value based on the capacitance between each of the plurality of electrostatic sensor electrodes and an indicator, A control unit that determines whether the indicator is in a proximity state, where it is close to the plurality of electrostatic sensor electrodes, based on the measurement value output by the measurement circuit, A storage unit that stores the measured values ​​as reference values ​​when the indicator is not in close proximity to the plurality of electrostatic sensor electrodes. Includes, The control unit, Based on the measured values, determine whether the proximity state is present. An electrostatic input device that, in the proximity state, updates the reference value if, after the measured value decreases, the amount of fluctuation in the measured value remains smaller than a predetermined value for a predetermined period of time or longer.

2. The control unit is Based on the first difference value obtained by subtracting the reference value from the measured value, it is determined whether the proximity state is present. The total difference value is calculated by summing the multiple first difference values ​​of the multiple electrostatic sensor electrodes. The electrostatic input device according to claim 1, wherein, in the proximity state, if the amount of change in the total difference value decreases and the state in which the amount of change in the total difference value remains smaller than a predetermined value for a predetermined time or longer, the reference value is updated.

3. The control unit, The storage unit is configured to store the highest total difference value as the maximum total difference value. The electrostatic input device according to claim 2, wherein it is determined that the total difference value has decreased when the second difference value obtained by subtracting the latest total difference value from the maximum total difference value is greater than a decrease threshold.

4. When the control unit determines that the proximity state is in place when the ambient temperature of the plurality of electrostatic sensor electrodes is lower than the temperature threshold, it stores the total difference value as the low-temperature total difference value in the storage unit. The electrostatic input device according to claim 3, wherein the reduction threshold is a first constant multiple of the total low-temperature difference value.

5. The control unit, If any of the above-mentioned multiple first difference values ​​is greater than the proximity threshold, it is determined that the proximity state exists. If the plurality of first difference values ​​are smaller than the non-proximity threshold, it is determined that the state is non-proximity. In the proximity state, if it is determined that the total difference value has decreased, and if any of the plurality of first difference values ​​exceeds the non-proximity threshold, the system transitions to the proximity monitoring state. In the proximity state, if it is determined that the total difference value has decreased, and if the plurality of first difference values ​​are less than the non-proximity threshold, the state transitions to the non-proximity monitoring state. The electrostatic input device according to claim 4, wherein, in the proximity monitoring state or the non-proximity monitoring state, if the increase in the total difference value is greater than a predetermined value, it is determined that the proximity state has been reached.

6. The electrostatic input device according to claim 5, wherein the control unit determines that the total difference value has increased when the second difference value becomes smaller than an increase threshold.

7. The electrostatic input device according to claim 6, wherein the augmentation threshold is a second constant multiple of the total low-temperature difference value.

8. The control unit, The electrostatic input device according to claim 6, wherein if the total difference value changes in the proximity monitoring state, it transitions to the proximity state.

9. The electrostatic input device according to claim 8, wherein the control unit transitions to the proximity state when the difference value obtained by subtracting the low-temperature total difference value from the total difference value is greater than a positive first change constant, or when the difference value obtained by subtracting the low-temperature total difference value from the total difference value is less than a negative second change constant.

10. The control unit updates the reference value if the non-proximity monitoring state continues for longer than the first update time, or if the proximity monitoring state continues for longer than the second update time. The electrostatic input device according to claim 9, wherein the first update time is shorter than the second update time.

11. The electrostatic input device according to claim 9, wherein, in the non-proximity monitoring state, if the total difference value is smaller than a predetermined minimum threshold that is extremely small, the control unit transitions to the non-proximity state without updating the reference value.

12. The system further includes a temperature sensor that measures the ambient temperature of the plurality of electrostatic sensor electrodes, The control unit, when it is determined that the proximity state is occurring when the ambient temperature of the plurality of electrostatic sensor electrodes is lower than a temperature threshold, provides the electrostatic input device according to any one of claims 1 to 11.

13. The control unit, when it is determined that the proximity state is occurring when the reference value is lower than a value corresponding to the reference value in a predetermined low-temperature state, provides the electrostatic input device according to any one of claims 1 to 11.

14. electrostatic sensor electrodes, A measurement circuit that outputs a measurement value based on the capacitance between the electrostatic sensor electrode and the indicator, A control unit that determines whether the indicator is in a proximity state, where it is close to the electrostatic sensor electrode, based on the measurement value output by the measurement circuit, A storage unit that stores the measured value as a reference value when the indicator is not in close proximity to the electrostatic sensor electrode. Includes, The control unit, Based on the measured values, determine whether the proximity state is present. An electrostatic input device that, in the proximity state, updates the reference value if, after the measured value decreases, the amount of fluctuation in the measured value remains smaller than a predetermined value for a predetermined period of time or longer.

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