JP2018116630A - Touch detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch detection device capable of accurately performing operation determination of a touch operation.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 an update threshold Rth, and stops the update of the reference value Ref when the capacity fluctuation value ΔC is the update threshold Rth or more. The touch detection device allows the reference Ref to be updated, if the capacity fluctuation value ΔC is less than the non-touch determination threshold OFFth and a capacity fluctuation range Cx is less than a fluctuation range threshold Ck.SELECTED DRAWING: Figure 5

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, in this type of touch detection device, it is necessary to accurately detect that a touch operation has been performed or a non-touch operation has been performed. In addition, when a hand or finger is brought close to the touch operation unit, the capacitance may change slightly, but when you re-touch from this state, you want to reliably detect the touch operation. There was also a need.

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

  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. An operation determination unit that determines a touch operation based on a threshold value and a non-touch determination threshold value, and an update operation that updates the reference value when a capacitance variation value that is a difference between the detected capacity and the reference value is less than an update threshold value When the capacitance variation value is equal to or greater than the update threshold value, the reference value update unit that stops the update operation, and the capacitance variation value is less than the non-touch determination threshold value, and is a fluctuation width of the detected capacitance. An update permission unit that permits an update operation of the reference value if the capacity variation width is less than the variation width threshold.

  By the way, for example, if the reference value update operation is permitted only when the capacitance fluctuation value is less than the update threshold, the capacitance fluctuation value is updated after detection of a non-touch operation in which the detected capacitance (capacitance) falls below the non-touch determination threshold. If it is not less than the threshold value, the update of the reference value cannot be resumed. Normally, there is no problem because the capacity fluctuation is less than the update threshold, but if the detection capacity is large due to temperature and humidity fluctuations, etc., the touch operation can be performed by the proximity of a hand or finger even though the touch operation is not performed. Misdetection.

  As a countermeasure, for example, by making the non-touch determination threshold value and the update threshold value the same, the update of the reference value can be resumed. In the case of this measure, even if temperature and humidity fluctuations occur in the surrounding environment, the reference value can follow the temperature and humidity fluctuations by updating the reference value, so even if the sensor electrode is touched again, this can be detected without any problems. Can do. However, when the detection capacity fluctuates due to the user's hand or finger approaching the touch operation unit, etc., even if the retouch operation is performed by pressing the hand or finger against the touch operation unit again, There is a possibility that the retouching operation cannot be detected because the amount of change in the detected capacitance is insufficient.

  Therefore, in the case of this configuration, if the capacitance fluctuation value is less than the non-touch determination threshold value and the capacitance fluctuation width that is the fluctuation width of the detected capacitance is less than the fluctuation width threshold value, the reference value update operation is permitted. Thereby, when the surrounding environment is changing, the update of the reference value is permitted. That is, the reference value cannot be updated when a hand, a finger, or the like is in proximity to the touch operation unit. Accordingly, when a retouch operation is performed from a state in which a hand, a finger, or the like is in proximity to the touch operation unit, the detection capacity is sufficiently changed, and it is possible to shift to a determination that there is a touch operation. Therefore, it is possible to accurately determine the operation of the touch operation.

  In the touch detection device, it is preferable that the update threshold is set to a value lower than the non-touch determination threshold. According to this configuration, since the update threshold value and the non-touch determination threshold value are different from each other, it is possible to separate the reference value update operation and the non-touch determination operation. Therefore, one process does not affect the other.

  In the touch detection device, it is preferable that the touch determination threshold is set to a value higher 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 reference value update 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.

  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, it is possible to accurately determine the operation of the touch operation.

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 does not fall below an update threshold value at the time of non-touch operation. The operation | movement figure of a touch detection apparatus when making a non-touch determination threshold value and the update threshold value the same. The operation | movement figure of a touch detection apparatus in case the update of a reference value is permitted when a capacity | capacitance fluctuation value becomes less than a non-touch determination threshold value, and a capacity | capacitance fluctuation width satisfies less than a fluctuation width threshold value.

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. The reference value update unit 8 performs an update operation when the capacity fluctuation value ΔC that is the difference between the detected capacity C and the reference value Ref is less than the update threshold Rth, and updates when the capacity fluctuation value ΔC is equal to or greater than the update threshold Rth. To stop. 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 an update permission unit 10 that sets whether or not the reference value Ref can be updated by the reference value update unit 8. The update permission unit 10 is provided in the controller 2. The update permission unit 10 performs the update operation of the reference value Ref if the capacitance fluctuation value ΔC is less than the non-touch determination threshold OFFth and the capacitance fluctuation width Cx that is the fluctuation width of the detected capacitance C is less than the fluctuation width threshold Ck. To give permission.

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, when the user is not operating the touch operation unit 3, the capacitance fluctuation value ΔC is less than the update threshold Rth. Therefore, the reference value update unit 8 executes the update operation of the reference value Ref based on the establishment of “ΔC <Rth”. 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 detection capacity C gradually increases in the process of the user touching the touch operation unit 3, and switches to the update threshold Rth or higher at a certain timing. The reference value update unit 8 stops the update operation of the reference value Ref at the timing when “ΔC ≧ Rth” 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 change, 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 capacity fluctuation value ΔC is less than the update threshold value Rth, the reference value Ref is updated, so that the reference value Ref is corrected to a value that follows the change in temperature and humidity. 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.

  However, 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 update threshold value Rth, the update operation of the reference value Ref is performed. Since it remains stopped, the update of the reference value Ref cannot be resumed even when a non-touch operation is performed. Furthermore, when the detection capacity C is large due to temperature and humidity fluctuations, the touch operation may be erroneously detected due to the proximity of a hand or a finger even though the touch operation unit 3 is not touched again. There is also sex.

  In this case, as shown in FIG. 4, for example, if the update threshold value Rth = non-touch determination threshold value OFFth, it is possible to restart the update of the reference value Ref after switching to the non-touch operation. That is, when the change in the detection capacity C is caused by temperature and humidity, the retouching operation can be detected by taking the coping method of update threshold Rth = non-touch determination threshold OFFth. However, in the case of this countermeasure, the capacitance fluctuation of the sensor electrode 4 is not a temperature / humidity change, for example, because the user's hand or finger swings close to the touch operation unit 3 (a state in which the user touches the touch operation unit 3 finely). If it occurs, there is a possibility that the detection capacity C does not increase sufficiently during the re-touch operation, and the touch operation cannot be detected.

  FIG. 5 illustrates a method for updating the reference value Ref of this example. As can be seen from the figure, the detection capacitance C changes slightly, not in a steady state. However, when the detection capacitance C changes due to a change in temperature and humidity, the change does not become extremely large. The width (capacity variation width Cx) is a small width. 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 ) Is 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 update permission unit 10 of the present example, when the capacity fluctuation value ΔC is less than the non-touch determination threshold OFFth and the capacity fluctuation width Cx that is the fluctuation width of the detected capacity C is less than the fluctuation width threshold Ck, The update operation of the reference value Ref is permitted. This is presumed that if the detected capacitance C is less than the non-touch determination threshold OFFth and the capacitance variation width Cx is less than the variation width threshold Ck, the possibility of capacitance variation due to temperature and humidity changes is high. Therefore, at this time, updating of the reference value Ref is permitted. This makes it possible to change the reference value Ref suitable for changes in the surrounding temperature and humidity, which is advantageous for accurately determining a touch operation.

  Now, for example, if the update operation of the reference value Ref is permitted only when the capacitance fluctuation value ΔC is less than the update threshold value Rth, the capacitance fluctuation value ΔC is detected after the non-touch operation in which the detected capacitance C falls below the non-touch determination threshold value OFFth. The update of the reference value Ref cannot be resumed unless it is less than the update threshold Rth. Normally, there is no problem because the capacitance fluctuation value ΔC is less than the update threshold Rth. However, when the detection capacitance C is large due to temperature / humidity fluctuation or the like, the touching operation is not performed, but the proximity of a hand or a finger. The touch operation is erroneously detected.

  As a countermeasure, for example, by making the non-touch determination threshold OFFth and the update threshold Rth the same, the update of the reference value Ref can be restarted. In the case of this countermeasure, even if temperature and humidity fluctuations occur in the surrounding environment, the reference value Ref can follow the temperature and humidity fluctuations by updating the reference value Ref. Can be detected. However, when the detection capacity C fluctuates due to the user's hand or finger approaching the touch operation unit 3 or the like, the retouch operation is performed by pressing the hand or finger strongly against the touch operation unit 3 again. However, there is a possibility that the retouch operation cannot be detected because the amount of change in the detection capacitance C is insufficient.

  Therefore, in the case of this example, if the capacitance fluctuation value ΔC is less than the non-touch determination threshold value OFFth and the capacitance fluctuation width Cx, which is the fluctuation width of the detected capacitance C, is less than the fluctuation width threshold value Ck, the reference value Ref is updated. To give permission. Thereby, when the surrounding environment is changing, the update of the reference value Ref is permitted. That is, the reference value Ref cannot be updated when a hand, a finger, or the like is in proximity to the touch operation unit 3. Therefore, when a touch operation is performed again from a state in which a hand, a finger, or the like is in proximity to the touch operation unit 3, the detection capacity C is sufficiently changed, and it is possible to shift to a determination that there is a touch operation. Therefore, the operation determination of the touch operation can be performed with high accuracy.

  The update threshold Rth is set to a value lower than the non-touch determination threshold OFFth. Thus, since the update threshold value Rth and the non-touch determination threshold value OFFth have different values, it is possible to separate the update operation of the reference value Ref and the non-touch determination operation. Therefore, one process does not affect the other.

  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 update operation of the reference value Ref is an operation for calculating the reference value Ref by a weighted average. Therefore, the reference value Ref can be calculated with high accuracy by a weighted average.
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, the non-touch determination threshold value OFFth, and the update threshold value Rth 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 update threshold value Rth and the non-touch determination threshold value OFFth may be set to the same value.
The touch detection device 1 can be applied to various devices and devices such as a palm rest.

  The logic for permitting update in this example can be similarly applied to the case where the detection capacity C decreases due to, for example, fluctuations in the surrounding environment.

  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 ... Update permission part, C (t) ... Electrostatic capacity, C ... Detected capacity, Ref. Reference value, ONth. Touch determination threshold, OFFth. Non-touch determination threshold, .DELTA.C. Capacity variation, Rth. Update threshold, 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;
When a capacity fluctuation value that is a difference between the detected capacity and the reference value is less than an update threshold, an update operation for updating the reference value is executed, and when the capacity fluctuation value is equal to or greater than an update threshold, the update operation is stopped. A reference value updating unit;
An update permission unit that permits an operation of updating the reference value if the capacitance variation value is less than the non-touch determination threshold value and a capacitance variation width that is a fluctuation width of the detected capacitance is less than a variation width threshold value. A touch detection device characterized by that. The touch detection device according to claim 1, wherein the update threshold is set to a value lower than the non-touch determination threshold. The touch detection device according to claim 1, wherein the touch determination threshold is set to a value higher than the non-touch determination threshold. The touch detection device according to claim 1, wherein the reference value update operation is an operation of calculating the reference value by a weighted average. 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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