JP2018116631A - Touch detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch detection device capable of securing determination accuracy of operation determination.SOLUTION: A touch detection device allows a touch determination threshold ONth and a non-touch determination threshold OFFth to be set based on a reference value Ref, and determines touch and non-touch by the comparison between the thresholds and a detection capacity C. The touch detection device executes the update of the reference value Ref when a capacity fluctuation value ΔC is less than the non-touch determination threshold OFFth, and stops the update of the reference value Ref when the capacity fluctuation value ΔC is the non-touch determination threshold OFFth or more. The touch detection device adjusts the non-touch determination threshold OFFth if the capacity fluctuation value ΔC is a value in a range within the touch determination threshold ONth and the non-touch determination threshold OFFth and a capacity fluctuation range Cx is less than a fluctuation range threshold Ck.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a touch detection device that detects a touch operation.

  Conventionally, a capacitance-type touch detection device (touch sensor) measures a capacitance that increases due to a touch operation, and determines that there is a touch operation when the value exceeds a predetermined threshold (Patent Literature). 1-3). However, the capacitance may increase or decrease due to factors other than the touch operation, which may cause malfunction. One cause of malfunction is, for example, temperature and humidity fluctuations in the surrounding environment.

Japanese Patent Laying-Open No. 2015-232542 JP-A-2015-231829 JP 2014-35605 A

  By the way, when the touch operation is not touched, there may be a situation where the capacitance does not fall below the non-touch determination threshold due to temperature and humidity fluctuations. In this case, since the determination is fixed in the touch determination state, some countermeasure is required.

  The objective of this invention is providing the touch detection apparatus which can ensure the determination precision of operation determination.

  The touch detection device that solves the problem includes a sensor electrode that detects a detection capacitance according to a touch operation, the detection capacitance that is obtained using a reference value as a measurement reference, and a touch determination that is determined based on a width of the detection capacitance with respect to the reference value. Based on the threshold and the non-touch determination threshold, an operation determination unit that determines a touch operation, and a capacitance fluctuation value that is a difference between the detected capacitance and the reference value is within the range of the touch determination threshold and the non-touch determination threshold. A threshold adjustment unit that takes a value and adjusts the non-touch determination threshold if the capacitance fluctuation width, which is the fluctuation width of the detected capacitance, is less than the fluctuation width threshold.

  According to this configuration, if the capacitance variation value is within the range of the touch determination threshold and the non-touch determination threshold, it can be determined that the detected capacitance is not below the non-touch determination threshold. Further, if the capacity fluctuation width is less than the fluctuation width threshold, it can be determined that the capacity fluctuation has occurred due to a change in the surrounding environment rather than a state in which the hand or the finger is close to the touch operation unit. For this reason, in the case of this configuration, if the capacitance variation value takes a value within the range of the touch determination threshold value and the non-touch determination threshold value, and the capacitance variation range is less than the variation range threshold value, the non-touch determination threshold value is adjusted. This makes it possible to reduce the detected capacity below the non-touch determination threshold value in a situation where the non-touch determination threshold value may be changed. For this reason, even if the detection capacity fluctuates due to a change in the surrounding environment, the operation determination is not fixed in the non-touch determination state. Therefore, it is possible to ensure the determination accuracy of the operation determination.

  In the touch detection device, when a capacitance variation value that is a difference between the detected capacitance and the reference value is less than a non-touch determination threshold value, an update operation is performed to update the reference value, and the capacitance variation value is determined to be a non-touch determination threshold value. At this time, it is preferable to provide a reference value update unit that stops the update operation. According to this configuration, the reference value is adjusted to an optimal value each time during the period in which the capacitance fluctuation value is less than the non-touch determination threshold value, which is further advantageous in ensuring the determination accuracy of the operation determination.

  In the touch detection device, when the reference value update unit has adjusted the non-touch determination threshold value by the threshold value adjustment unit, the state where the capacitance fluctuation range is less than the fluctuation range threshold value continues for a certain period of time. The reference value updating operation is preferably executed. According to this configuration, after the non-touch determination threshold value is adjusted by the threshold value adjustment unit, after confirming whether or not the state in which the capacitance fluctuation range is less than the fluctuation range threshold value continues for a certain period of time, Update. Therefore, since the reference value is updated only under a situation where the detection capacity is assumed not to fall below the non-touch determination threshold due to a change in the surrounding environment, it is difficult to cause a situation where the reference value is set to an inappropriate value. It becomes possible.

  In the touch detection device, it is preferable that the touch determination threshold is set to a value larger than the non-touch determination threshold. According to this configuration, in the non-touch determination state, it is possible to determine that there is a touch operation when the detection capacity is sufficiently increased, and in the touch determination state, the touch operation is performed when the detection capacity is sufficiently reduced. It can be determined that there is none.

  In the touch detection device, it is preferable that the capacitance fluctuation range is a width between adjacent peaks and bottoms in the waveform of the detection capacitance. According to this configuration, it is possible to detect the capacity fluctuation range by a simple process of monitoring the peak and bottom of the waveform of the detected capacity.

  According to the present invention, the determination accuracy of the operation determination can be ensured.

The block diagram of the touch detection apparatus of one Embodiment. The operation | movement figure of a touch detection apparatus when normal touch operation / non-touch operation is performed. The operation | movement figure of a touch detection apparatus when a detection capacity | capacitance is not less than a non-touch determination threshold value at the time of non-touch operation. FIG. 10 is an operation diagram of the touch detection device when the non-touch determination threshold is adjusted when the capacitance variation value takes a value within the range of the touch determination threshold and the non-touch determination threshold and the capacitance variation width is less than the variation width threshold.

Hereinafter, an embodiment of the touch detection device will be described with reference to FIGS.
As shown in FIG. 1, the touch detection device 1 includes a controller 2 that controls the operation of the touch detection device 1 and a sensor electrode 4 that detects a touch operation of the touch operation unit 3. The sensor electrode 4 includes an electrode group disposed in a dot shape over the entire back surface of the touch operation unit 3. The sensor electrode 4 detects a change in capacitance according to the touch operation, and outputs a capacitance C (t) to the controller 2 as a detection signal. The controller 2 detects a user's touch operation on the touch operation unit 3 based on the capacitance C (t) input from the sensor electrode 4.

  The touch detection device 1 includes an operation determination unit 7 that determines a touch operation based on the capacitance C (t) input from the sensor electrode 4. The operation determination unit 7 is provided in the controller 2. The operation determination unit 7 touches based on the detection capacity C obtained using the reference value Ref of touch operation determination as a measurement reference, the touch determination threshold ONth and the non-touch determination threshold OFFth determined from the width of the detection capacity C with respect to the reference value Ref. Determine the operation. The touch determination threshold value ONth and the non-touch determination threshold value OFFth are set to a magnitude relationship of “ONth> OFFth”.

  In the non-touch determination state (a state in which it is determined that there is no touch), the operation determination unit 7 determines that the touch determination state (a state in which it is determined that there is a touch operation) if the detection capacity C is equal to or greater than the touch determination threshold ONth. recognize. Further, the operation determination unit 7 recognizes the non-touch determination state when the detection capacity C is equal to or less than the non-touch determination threshold OFFth in the touch determination state.

  The touch detection device 1 includes a reference value update unit 8 that updates the reference value Ref during a period when the touch operation is not performed. The reference value update unit 8 is provided in the controller 2. In this example, the threshold value for switching whether or not the reference value Ref can be updated is set to the same value as the non-touch determination threshold value OFFth. Therefore, the reference value updating unit 8 executes the update operation when the capacitance fluctuation value ΔC that is the difference between the detected capacitance C and the reference value Ref is less than the non-touch determination threshold OFFth, and the capacitance fluctuation value ΔC is the non-touch determination threshold OFFth. At this time, the update operation is stopped. The update operation of the reference value Ref is preferably an operation for calculating the reference value Ref by a weighted average, for example. Then, the reference value update unit 8 calculates an optimum reference value Ref taking into account the surrounding environment (for example, temperature and humidity change) at any time during the period when the update operation is valid.

  The touch detection device 1 includes a threshold adjustment unit 10 that adjusts the non-touch determination threshold OFFth so that the determination state that the operation state of the touch operation unit 3 is the touch state is not fixed due to a change in the surrounding environment. Prepare. The threshold adjustment unit 10 is provided in the controller 2. In the threshold adjustment unit 10 of this example, the capacitance fluctuation value ΔC takes a value within the range of the touch determination threshold ONth and the non-touch determination threshold OFFth, and the capacitance fluctuation width Cx that is the fluctuation width of the detected capacitance C is the fluctuation width threshold Ck. If not, the non-touch determination threshold value OFFth is adjusted.

Next, operations and effects of the touch detection device 1 according to the embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 2, when the user is not operating the touch operation unit 3, the capacitance C (t) of the sensor electrode 4 takes a low value near the reference value Ref. Note that the change in the capacitance C (t), that is, the detection capacitance C fluctuates while increasing or decreasing in a minute range due to the influence of the surrounding environment. In the non-touch state, the capacitance fluctuation value ΔC is less than the touch determination threshold value ONth. Therefore, the operation determination unit 7 determines that the touch operation has not yet been performed based on the establishment of “ΔC <ONth”, and maintains the determination of “non-touch state”.

  In addition, the reference value update unit 8 performs the update operation of the reference value Ref based on the current operation state of the touch operation unit 3 being the non-touch state (“ΔC <ONth” is established). Therefore, the reference value Ref is set to a suitable value by calculating the weighted average in the non-touch state.

  Here, it is assumed that the user touches the touch operation unit 3. When the operation state of the touch operation unit 3 is switched to the touch state, the capacity fluctuation value ΔC becomes equal to or greater than the touch determination threshold value ONth. Therefore, the operation determination unit 7 determines that the operation state of the touch operation unit 3 has become the “touch state” based on the establishment of “ΔC ≧ ONth”.

  Further, the reference value update unit 8 stops the update operation of the reference value Ref at the timing when “ΔC ≧ OFFth” is satisfied. Therefore, the reference value Ref is not set to a value according to the high capacitance output at the time of the touch operation.

  It is assumed that the temperature and humidity of the surrounding environment have increased after the operation state of the touch operation unit 3 is switched to the touch state. When the temperature and humidity rise, the capacitance C (t) of the sensor electrode 4, that is, the detection capacitance C changes to a higher value than at normal temperature. For this reason, when the touch state is switched to the non-touch state, the detection capacity C decreases, but becomes a value different from that before the touch operation. At this time, if the capacitance fluctuation value ΔC is less than the non-touch determination threshold value OFFth, the determination of the operation state is switched to the “non-touch state” without any problem.

  Further, when the capacitance fluctuation value ΔC becomes less than the non-touch determination threshold value OFFth, the update operation of the reference value Ref is also resumed, so that the reference value Ref is corrected to a value following the temperature and humidity change. Therefore, when the touch operation is performed again, it is possible to determine whether there is a touch operation with the same conditions as the previous touch operation, that is, with the same touch operation sensitivity.

  On the other hand, as shown in FIG. 3, when the operation state of the touch operation unit 3 is switched from the touch state to the non-touch state, if the capacitance fluctuation value ΔC is equal to or greater than the non-touch determination threshold OFFth, the operation state is determined. It is not possible to shift to the “non-touch state”. Normally, even if the capacitance fluctuation value ΔC decreases during the touch operation, the non-touch determination threshold value OFFth is exceeded because the user is placing the hand or finger close to the touch operation unit 3 (the hand or finger is approaching finely). In this case, there is no problem. However, if the capacitance fluctuation value ΔC is maintained at the non-touch determination threshold OFFth or more due to temperature and humidity fluctuations, the operation state determination is stuck in the “touch state”, and this needs to be dealt with.

  FIG. 4 illustrates a method for adjusting the non-touch determination threshold value OFFth of this example. As can be seen from the figure, the detection capacitance C changes slightly, not in a steady state, but when the detection capacitance C increases due to temperature and humidity changes, the detection capacitor C has a small capacitance width (capacitance variation width Cx). become. This is because the temperature and humidity are assumed to change gradually, and the capacity fluctuation caused by this is assumed to change little by little following the temperature and humidity change. Note that the capacitance variation width Cx of this example is a width between adjacent peaks and bottoms in the waveform of the detection capacitance C.

  On the other hand, for example, when a situation such as the user's hand or finger swinging close to the touch operation unit 3 (a state in which the hand or finger approaches or separates finely) occurs, the capacity width of the detection capacity C (capacity variation width Cx ) Takes a big width. In this example, this phenomenon is used to distinguish between a capacitance variation caused by a change in temperature and humidity and a capacitance variation caused by the proximity of a user's hand or finger.

  Based on the above, the threshold adjustment unit 10 takes a value within the range of the touch determination threshold value ONth and the non-touch determination threshold value OFFth, and the capacitance fluctuation range Cx that is the fluctuation width of the detected capacitance C is the fluctuation range threshold value. If it is less than Ck, the non-touch determination threshold value OFFth is changed by a predetermined amount. That is, when the capacitance fluctuation value ΔC during the touch operation decreases more than a certain value and the capacitance fluctuation width Cx is small, the non-touch determination threshold OFFth is increased by a predetermined amount on the assumption that there is a possibility of shifting to the non-touch operation. Let As a result, the detection capacity C can be made lower than the non-touch determination threshold value OFFth.

  However, the situation in which the reduced detection capacity C does not fall below the non-touch determination threshold value OFFth may be caused by, for example, the user's hand or finger being brought close to the touch operation unit 3. That is, when the touch operation unit 3 is firmly touched with a hand or a finger, the state described above may occur when the touch operation unit 3 is switched to a lightly touched state. At this time, when returning to the state in which the hand or finger lightly touching the touch operation unit 3 is firmly pressed (when the reduced number of touch points is restored), the determination of the touch state must be maintained. Don't be.

  Therefore, the reference value update unit 8 maintains the update operation of the reference value Ref in a stopped state even if the condition for adjusting the non-touch determination threshold value OFFth is satisfied. When the reference value update unit 8 confirms that the state in which the capacity fluctuation width Cx is less than the fluctuation width threshold Ck has continued for a certain period of time, it determines that a change in temperature and humidity has occurred in the surrounding environment, and updates the reference value Ref. Perform the action. Therefore, even under this situation, the reference value Ref can be adjusted to a suitable value following the temperature and humidity change.

  In the case of this example, if the capacitance fluctuation value ΔC is within the range of the touch determination threshold ONth and the non-touch determination threshold OFFth, it can be determined that the detected capacitance C is not less than the non-touch determination threshold OFFth. Further, if the capacity fluctuation width Cx is less than the fluctuation width threshold Ck, it can be determined that the capacity fluctuation has occurred due to a change in the surrounding environment, not a hand, a finger or the like being in proximity to the touch operation unit 3. It is. Therefore, in this example, if the capacitance variation value ΔC takes a value within the range of the touch determination threshold value ONth and the non-touch determination threshold value OFFth, and the capacitance variation width Cx is less than the variation width threshold value Ck, the non-touch determination threshold value Adjust OFFth. This makes it possible to lower the detection capacity C with respect to the non-touch determination threshold value OFFth under circumstances where the non-touch determination threshold value OFFth may be changed. For this reason, even if the detection capacity C fluctuates due to a change in the surrounding environment, the operation determination is not fixed in the non-touch determination state. Therefore, the determination accuracy of the operation determination can be ensured.

  The touch detection device 1 includes a reference value update unit 8 that can update the reference value Ref. The reference value update unit 8 of this example updates the reference value Ref when the capacitance variation value ΔC is less than the non-touch determination threshold value OFFth, and updates the reference value Ref when the capacitance variation value ΔC is equal to or greater than the non-touch determination threshold value OFFth. To stop. Therefore, since the reference value Ref is adjusted to an optimum value each time during the period when the capacitance fluctuation value ΔC is less than the non-touch determination threshold value OFFth, it is advantageous to ensure the determination accuracy of the operation determination.

  After the adjustment of the non-touch determination threshold value OFFth by the threshold value adjustment unit 10, the reference value update unit 8 confirms whether or not the state in which the capacitance fluctuation range Cx is less than the fluctuation range threshold value Ck continues for a certain period of time. Then, the reference value Ref is updated. Therefore, since the reference value Ref is updated only under a situation where the detection capacitance C is assumed not to fall below the non-touch determination threshold value OFFth due to a change in the surrounding environment, a situation occurs in which the reference value Ref is set to an inappropriate value. Can be difficult.

  The touch determination threshold value ONth is set to a value higher than the non-touch determination threshold value OFFth. Therefore, in the non-touch determination state, it can be determined that there is a touch operation when the detection capacity C increases sufficiently, and in the touch determination state, it is determined that there is no touch operation when the detection capacity C decreases sufficiently. can do.

  The capacitance variation width Cx is a width between adjacent peaks and bottoms in the waveform of the detection capacitance C. Therefore, the capacity fluctuation width Cx can be detected by a simple process of monitoring the peak and bottom of the waveform of the detected capacity C.

Note that the embodiment is not limited to the configuration described so far, and may be modified as follows.
The reference value Ref update operation is not limited to processing using a weighted average, and can be changed to various methods.

  The capacitance variation width Cx is not limited to the width between the adjacent peak and bottom in the waveform of the detection capacitance C. The capacitance fluctuation width Cx may be a parameter that can determine the magnitude of the fluctuation amount of the detection capacitance C, such as the slope of the waveform of the detection capacitance C, for example.

The touch determination threshold value ONth and the non-touch determination threshold value OFFth are not limited to the width value of the detection capacitor C, and may be actual values, for example.
-The surrounding environment that affects the variation of capacitance C (t) includes other factors besides temperature and humidity.

The touch detection device 1 can be applied to various devices and devices such as a palm rest.
The threshold adjustment logic of this example can be similarly applied to the case where the detection capacity C decreases due to, for example, fluctuations in the surrounding environment.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(A) In the touch detection device, the reference value updating operation is an operation for calculating the reference value by a weighted average. According to this configuration, the reference value can be calculated with high accuracy by a weighted average.

  DESCRIPTION OF SYMBOLS 1 ... Touch detection apparatus, 2 ... Controller, 3 ... Touch operation part, 4 ... Sensor electrode, 7 ... Operation determination part, 8 ... Reference value update part, 10 ... Threshold adjustment part, C (t) ... Electrostatic capacity, C ... Detection capacity, Ref. Reference value, ONth. Touch determination threshold, OFFth. Non-touch determination threshold, .DELTA.C. Capacity variation, Cx. Capacity variation, Ck. Variation threshold.

Claims (5)

A sensor electrode for detecting a detection capacitance according to a touch operation;
An operation determination unit for determining a touch operation based on the detection capacity obtained using a reference value as a measurement reference, and a touch determination threshold and a non-touch determination threshold determined from a width of the detection capacity with respect to the reference value;
The capacitance fluctuation value that is the difference between the detected capacitance and the reference value takes a value within the range of the touch determination threshold and the non-touch determination threshold, and the capacitance fluctuation width that is the fluctuation width of the detection capacitance is less than the fluctuation width threshold. If so, a touch detection apparatus comprising: a threshold adjustment unit that adjusts the non-touch determination threshold. When a capacitance variation value that is a difference between the detected capacitance and the reference value is less than a non-touch determination threshold, an update operation is performed to update the reference value, and when the capacitance variation value is equal to or greater than a non-touch determination threshold, the update is performed. The touch detection device according to claim 1, further comprising a reference value update unit that stops the operation. The reference value update unit updates the reference value when a state in which the capacitance fluctuation range is less than the fluctuation range threshold value continues for a certain period of time after the non-touch determination threshold value is adjusted by the threshold adjustment unit. The touch detection device according to claim 2 which performs operation. The touch detection device according to claim 1, wherein the touch determination threshold is set to a value larger than the non-touch determination threshold. The touch detection device according to any one of claims 1 to 4, wherein the capacitance fluctuation range is a width between an adjacent peak and bottom in a waveform of the detection capacitance.

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