Electronic device and touch detection method

Abstract

To provide an electronic device and a touch detection method that can suppress noise generation while improving detection precision for an object of operation such as a glove.SOLUTION: A capacitance type touch panel device 100 includes a controller 110 and a touch panel 120. The controller 110 includes: a drive part 112 which scans sensor lines 124 with a scan signal; a measurement part 114 which measures the capacitance of a scanned sensor line 124; a touch detection / coordinate calculation part 116 which detects a touch on an object of operation and calculates coordinates of the touch position based upon the measurement result of the measurement part 114; and a gain switching control part 118 which controls switching of the gain of the scan signal. The gain switching control part 116 enables the coordinates of the touch position of the glove to be calculated by increasing the gain of the scan signal when the touch of the glove is detected.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electronic device using a capacitive touch panel, and more particularly to a method for detecting a glove touch. [Background technology]

[0002] The touch panel is mounted in a display unit together with a liquid crystal panel or the like as an input interface that detects touch operations by the user. For example, Patent Document 1 discloses a capacitance-type touch sensor. Furthermore, Patent Documents 2 and 3 disclose touch input devices that can detect touch operations even when the user is wearing gloves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-182185 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-164795 [Patent Document 3] Japanese Patent Application Publication No. 2019-144891 Summary of the Invention [Problem to be solved by the invention]

[0004] With capacitive touch panels, it is difficult to correctly detect touch operations when wearing gloves due to electrostatic sensitivity. Conventional detection methods set the gain of the scan signal so that the delta value (detected capacitance - baseline value) required for coordinate calculation can be secured from the beginning, even when wearing gloves, and use two types of thresholds to detect both bare finger and gloved touches.

[0005] As shown in FIG. 1(A), for example, when the capacitance detection level when a bare hand touches the sensor is approximately "150," the threshold value Th1 for detecting a bare hand touch is set to "100," and the threshold value Th2 for detecting a gloved touch is set to "50." When the detected capacitance exceeds the threshold value Th1 (solid waveform), the coordinates of the bare hand touch position are calculated as shown in FIG. 1(B). When the detected capacitance is less than the threshold value Th1 and exceeds the threshold value Th2 (dashed waveform), the coordinates of the gloved touch position are calculated as shown in FIG. 1(C). The coordinates are calculated by subtracting a certain threshold value (baseline value) from the detected capacitance to remove noise components and using the remaining data. Furthermore, when a gloved touch is detected, a flag indicating a gloved touch is set in the calculated coordinates.

[0006] In recent years, knob-on-display (KoD) has been put to practical use. Knobs are attached as controls on a touch panel display, and operations such as rotation are given to the knob. Knobs are products with a structure that makes them less sensitive than electrostatic sensors, and they must be able to detect not only indirect touch when the knob is operated with bare hands, but also when operated with gloves on.

[0007] When the gain of the scan signal (or drive signal) used to detect touch is constant, the change in capacitance detected when a glove is touched is smaller than the change in capacitance detected when a bare hand is touched, resulting in reduced detection sensitivity. Increasing the gain of the scan signal improves detection sensitivity by making it easier to pick up signal components that change capacitance. However, if the gain of the scan signal is always set high enough to calculate the coordinates of the glove's touch position, EMC noise increases, adversely affecting the surrounding area.

[0008] The present invention aims to solve the above-mentioned conventional problems and to provide an electronic device and a touch detection method that improve the detection accuracy of an operation target such as a glove or a mitten while suppressing the generation of noise. [Means for solving the problem]

[0009] An electronic device equipped with a capacitive touch panel according to the present invention includes a driving means for scanning the touch panel with a scan signal, a measuring means for measuring the capacitance of the touch panel when scanned with the scan signal, a detecting means for detecting a touch of an object to be operated on the touch panel based on the measurement result of the measuring means, and a control means for controlling switching of the gain of the scan signal, wherein the control means increases the gain of the scan signal when a touch of an object to be operated is detected when scanning with a scan signal having a small gain.

[0010] In one aspect, the detection means detects a touch of the operation object based on multiple measurement results of the measurement means. In one aspect, the detection means further includes calculation means for calculating coordinates of a touch position of the operation object based on the capacitance of multiple points measured by the measurement means, and the calculation means calculates the coordinates of the touch position of the operation object based on measurement results when scanning with a scan signal having a large gain. In one aspect, the operation object is a worn glove, a mitten, or an equivalent thereof.

[0011] A touch detection method according to the present invention is for an electronic device equipped with a capacitive touch panel, and includes detecting a touch of an object to be operated based on capacitance measured when the touch panel is scanned with a scan signal having a first gain, and calculating, in response to the detection of the touch of the object to be operated, coordinates of a touch position of the object to be operated based on capacitance measured when the touch panel is scanned with a scan signal having a second gain greater than the first gain. In one embodiment, the detection method further includes switching from the scan signal having the first gain to the scan signal having the second gain when the touch of the object to be operated is detected. [Effects of the Invention]

[0012] According to the present invention, if a touch of an operation object is detected when scanning with a scan signal having a small gain, the gain of the scan signal is increased, so that even an operation object such as a glove can be detected with high accuracy, and on the other hand, the generation of noise can be suppressed by reducing the gain of the scan signal. [Brief explanation of the drawings]

[0013] [Figure 1] 1A and 1B are diagrams illustrating problems with conventional capacitive touch panels. [Figure 2] FIG. 2(A) is a diagram showing a schematic overall configuration of a touch panel device according to an embodiment of the present invention, and FIG. 2(B) is a diagram showing a functional configuration of a controller of FIG. 2(A). [Figure 3] FIG. 3(A) is a diagram showing an example of the capacitance formed when a finger touches a touch panel, FIG. 3(B) is a diagram showing an example of the configuration of a detection circuit of a touch panel device according to an embodiment of the present invention, and FIG. 3(C) is a diagram showing an example of the detection signal in the detection unit when scan signals with different gains are applied. [Figure 4] 5A and 5B are diagrams illustrating an example of calculation of coordinates (touch position) of the touch panel device according to the embodiment of the present invention. [Figure 5] 10 is a flow chart showing an algorithm for glove detection in a touch panel device according to an embodiment of the present invention. [Figure 6] FIG. 6A is a diagram showing an example of detection when scanning is performed with a scan signal having a small gain, and FIG. 6B is a diagram showing an example of detection when scanning is performed with a scan signal having a large gain. [Figure 7] 10 is a flow chart showing another algorithm for glove detection in the touch panel device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described. An electronic device according to the present invention includes a capacitive touch panel and detects touch operations and touch positions of an operation target (for example, a user's finger, hand, or worn glove). The electronic device according to the present invention includes, for example, a display having a touch panel mounted on a liquid crystal panel, and provides a display device or display unit including a user input interface function via the touch panel. The electronic device according to the present invention is used, for example, in an in-vehicle device, a multi-function mobile phone (smartphone), a portable information terminal (tablet computer, laptop computer, notebook computer), etc. [Example]

[0015] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 2(A) is a diagram showing a schematic overall configuration of a touch panel device according to an embodiment of the present invention, and Fig. 2(B) is a diagram showing a functional configuration of the controller of Fig. 2(A). The touch panel device 100 includes a controller 110 and a capacitive touch panel 120 electrically connected to the controller 110.

[0016] The touch panel 120 has a plurality of sensor patterns on a substrate, such as a glass substrate or a plastic substrate, for detecting the capacitance of an operation target, such as a finger. The arrangement, shape, size, and number of the sensor patterns are arbitrary, but the example in FIG. 2(A) shows rectangular pads 122 arranged at a constant pitch as the sensor pattern. Other examples of sensor patterns include a diamond pattern in which a plurality of diamond-shaped pads are arranged. Note that while FIG. 2(A) shows a simplified arrangement of 3 rows and 5 columns of pads for ease of explanation, it should be noted that in reality, a larger number of pads may be arranged depending on the size of the touch panel.

[0017] The pads 122 are made of a transparent metal material (e.g., ITO), and one end of a corresponding sensor line 124 is electrically connected to each of the multiple pads 122, and the other end of each of the sensor lines 124 is electrically connected to the controller 110. In the example of FIG. 2(A), the sensor lines 124 in the X direction (row direction) are connected to each pad 122, but this is not limiting, and sensor lines in the X direction and Y direction may be connected to each pad 122 according to the arrangement of the sensor pattern.

[0018] The controller 110 is configured using hardware resources and / or software resources, and controls the overall operation of the touch panel 120. For example, the controller 110 is configured from a microcontroller including ROM / RAM, a microprocessor, a signal processor, or the like.

[0019] As shown in FIG. 2(B), the controller 110 includes a drive unit 112 that scans (drives) the sensor line 124 with a scan signal, a measurement unit 114 that measures the capacitance of the sensor line 124 driven by the scan signal, a touch detection / coordinate calculation unit 116 that detects whether or not an operation object has touched the touch panel 120 based on the measurement results of the measurement unit 114 and calculates the coordinates of the touch position, and a gain switching control unit 118 that controls switching of the gain of the scan signal of the drive unit 112.

[0020] The driver 112 includes a scan signal generator that generates a scan signal having a square wave or pulse of a constant frequency, and each sensor line 124 is driven by the scan signal generated by the scan signal generator. The driver 112 may drive multiple sensor lines 124 simultaneously or in a time-division manner. In the latter case, a multiplexer or the like is provided that selectively switches the connection between the driver 112 and each of the multiple sensor lines 124.

[0021] The measurement unit 114 measures the capacitance of the line sensor itself, which is driven by the scan signal from the drive unit 112, and provides the measurement result to the touch detection / coordinate calculation unit 116. As shown in FIG. 1(A), the touch detection / coordinate calculation unit 116 includes settings for a threshold for detecting a touch by a bare hand and a threshold for detecting a touch by a glove, and compares these thresholds with the capacitance measured by the measurement unit 114 to detect the presence or absence of a touch by a bare hand / glove, and further calculates the coordinates of the touch position if a touch is detected. The settings for the threshold for detecting a touch by a bare hand and the threshold for detecting a touch by a glove can be changed when the gain of the scan signal is switched, as will be described later.

[0022] Gain switching control unit 118 controls switching of the gain (peak value, voltage) of the scan signal generated by drive unit 112, based on the measurement results of measurement unit 114 and / or the touch detection results of touch detection / coordinate calculation unit 116. Specifically, drive unit 112 normally scans touch panel 120 with a scan signal with a low gain, but when touch detection / coordinate calculation unit 116 detects a gloved touch, gain switching control unit 118 controls drive unit 112 to temporarily increase the gain of the scan signal, causing touch panel 120 to be scanned with a scan signal with a high gain, thereby enabling calculation of the coordinates of the gloved touch position. At the same time, gain switching control unit 118 changes the settings of the threshold for detecting a bare hand touch and the threshold for detecting a gloved touch of touch detection / coordinate calculation unit 116 to match the gain of the scan signal.

[0023] FIG. 3(A) shows how a hand or finger F touches the touch panel 120, and FIG. 3(B) shows an example configuration of a touch detection circuit. When performing touch detection, the controller 110 scans each sensor line 124 with a scan signal and measures the capacitance on the sensor line. When a hand or finger (including a gloved hand) F touches or approaches the touch panel 120, the hand or finger F capacitively couples with the pad 122, causing a change in the capacitance of the detection unit. The measurement unit 114 measures the capacitance of the detection unit, i.e., the capacitance of the sensor line itself driven by the scan signal.

[0024] Figure 3(C) shows the pulse waveform of the scan signal and the waveform of the signal measured by the detection unit. The solid line indicates a scan signal with a high gain, and the dashed line indicates a scan signal with a low gain. Any method for detecting changes in capacitance can be used, but there are no particular limitations. For example, changes in capacitance can be measured by the accentuation of the square wave of the scan signal measured by the detection unit. In this case, the higher the gain of the scan signal, the easier it is to detect changes in capacitance, resulting in better sensitivity. For example, comparing the detection levels after a certain time S has elapsed from the rising edge of the pulse, we can see that the change D2 of the square wave with a high gain (dashed line) is greater than the change D1 of the square wave with a low gain (solid line).

[0025] Next, a method for calculating the coordinates of a touch position will be described. Assuming that a finger F touches the vicinity of the lower part of the pad 122A, as shown in Fig. 4(A). The measurement unit 114 measures the capacitance via the sensor line 124 and provides the measurement result to the touch detection / coordinate calculation unit 116.

[0026] The touch detection / coordinate calculation unit 116 receives the measurement results from the measurement unit 114 and calculates the difference between the measured value and the average value of the measured value over a relatively long measurement period (multiple scans), thereby obtaining a calculation result such as that shown in FIG. 4B. Pad 122A has the highest capacitance. Next, the touch detection / coordinate calculation unit 116 subtracts a threshold value from the calculated difference to remove noise components, obtaining a calculation result such as that shown in FIG. 4C. In this example, the threshold value is "60," and if the result of subtracting the threshold value is negative, the calculation result is shown as "0." Next, the touch detection / coordinate calculation unit 116 calculates the center of gravity position from the capacitances of the multiple pads to obtain the coordinates of the touch position. In this example, the capacitances of the four pads are "110," "80," "40," and "20," respectively, and calculates the center of gravity position P from these values. To calculate the coordinates of the touch position more accurately, the capacitances of the multiple pads must remain after removing the noise components. The gain of the scan signal is set so that such capacitances can be ensured.

[0027] The advantage of using the coordinate calculation method described above is that, although accurate coordinates cannot be obtained using information from only one pad, more accurate coordinates can be obtained by using information from multiple pads. For example, if only the measurement results of Figure 4(B) are used, the pad with the largest capacitance is pad 122A, which has a capacitance of "170", and the coordinates of the touch position obtained from this information are the center point of pad 122A, which will be offset from the actual touch position of finger F.

[0028] Next, the touch detection operation of the touch panel device of this embodiment will be described with reference to the flow in Fig. 5. When detecting a touch operation on the touch panel 120, the drive unit 112 normally scans the touch panel 120 with a scan signal with a small gain (S100). This is shown in Fig. 6(A). The touch detection / coordinate calculation unit 116 compares the capacitance measured by the measurement unit 114 with a threshold value Th1_A for detecting a touch by a bare hand / a threshold value Th2_A for detecting a touch by a glove, and detects whether or not there has been a touch by a bare hand or a touch by a glove.

[0029] The gain of the scan signal is set to a level that is sufficiently sensitive to calculate the coordinates of a bare hand touch, but not to calculate the coordinates of a gloved touch, but sufficient to detect the possibility of a gloved touch. Reducing the gain of the scan signal reduces the sensitivity for detecting capacitance changes. However, since the detection level of capacitance changes is high in the case of a bare hand touch, even if the gain is reduced to a certain extent, sufficient sensitivity can be obtained to calculate the coordinates of a bare hand touch. On the other hand, since the detection level of capacitance changes is low in the case of a gloved touch, reducing the gain makes it difficult to retain the capacitance of multiple pads after noise removal, making it difficult to calculate the coordinates. However, the gain is set to a level that enables detection of a gloved touch on at least one pad, i.e., a level sufficient to detect the possibility of a gloved touch.

[0030] Based on the measurement results from scanning with a scan signal having a low gain, if the capacitance is greater than or equal to Th1_A (S110), the touch detection / coordinate calculation unit 116 detects a bare hand touch and calculates the coordinates of the touch position (S120). Meanwhile, the touch detection / coordinate calculation unit 116 monitors whether the capacitance is greater than or equal to the threshold value Th2_A (S130). If the capacitance exceeds the threshold value Th2_A, the touch detection / coordinate calculation unit 116 detects the possibility of a gloved touch and provides the detection result to the gain switching control unit 118. In response to the detection of the possibility of a gloved touch, the gain switching control unit 118 instructs the drive unit 112 to switch the scan signal gain to a higher value. As a result, the drive unit 112 performs scanning with a scan signal having a high gain (S140). Furthermore, in accordance with the gain switching, the gain switching control unit 118 instructs the touch detection / coordinate calculation unit 116 to switch the threshold value Th1_A for detecting a bare hand and the threshold value Th2_A for detecting a gloved hand to threshold values ​​Th1_B and Th2_B that are slightly higher. This state is shown in FIG. 6(B).

[0031] When the capacitance is equal to or greater than the threshold value Th2_B (S150), the touch detection / coordinate calculation unit 116 calculates the coordinates of the glove touch position (S160). That is, the touch detection / coordinate calculation unit 116 calculates the coordinates of the glove touch position from the capacitances of multiple pads. On the other hand, if the capacitance is not equal to or greater than the threshold value Th2_B even after a certain period of time or a certain number of scans, the gain switching control unit 118 determines that the glove is not touching the pad, and returns the gain of the scan signal of the drive unit 112 to the original small gain.

[0032] 7 is a flow showing another touch detection operation, and steps S100 to S160 are the same as those in FIG. 5. Here, when it is detected that the capacitance is equal to or greater than the threshold value Th2_A (S130), it is determined whether the multiple average of multiple scans is equal to the threshold value Th2_A (S200). By calculating the weighted average, noise components can be removed, erroneous detection of the possibility of a glove touch can be suppressed, and the accuracy of glove touch detection can be improved.

[0033] As described above, according to this embodiment, under normal circumstances, scanning is performed with a scan signal having a small gain, making it possible to calculate the coordinates of the bare hand touch position and detect the possibility of a gloved touch, and when the possibility of a gloved touch is detected, scanning is performed with an increased gain of the scan signal, making it possible to calculate the coordinates of the gloved touch position, so that gloved touch can be detected with high accuracy while suppressing the generation of EMC noise.Furthermore, in this embodiment, the gain is increased only in the special case of detecting a gloved touch, so the frequency of EMC noise generation can be reduced compared to conventional cases where the gain of the scan signal is always increased.

[0034] In the above embodiment, a self-capacitance method is shown in which a change in capacitance of the driven line sensor itself is detected, but this is not limited to this, and the present invention can also be applied to a mutual capacitance method in which a change in capacitance of a line sensor that intersects with the driven line sensor is detected. Furthermore, in the above embodiment, an example of detecting the touch of a glove worn on a finger is shown, but this is not limited to this, and the present invention can also be applied to detecting the touch when wearing gloves equivalent to a glove, finger cots, etc. In the above embodiment, a rectangular wave is used as the scan signal, but the present invention is not limited to this and can also be applied to cases where a sine wave is used as the scan signal. A sine wave has less radiation noise than a rectangular wave and is therefore more advantageous in terms of EMC measures.

[0035] Although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the gist of the invention described in the claims. [Explanation of symbols]

[0036] 100: Touch panel device 110: Controller 112: Drive unit 114: Measurement unit 116: Touch detection / coordinate calculation unit 118: Gain switching control unit 120: Touch panel 122: Pad 124: Sensor line

Claims

1. An electronic device equipped with a capacitive touch panel, a driving means for scanning the touch panel with a scan signal; a measuring means for measuring the capacitance of the touch panel when scanned with the scan signal; a detection means for detecting a touch of an operation object on the touch panel based on the measurement result of the measurement means; a control means for controlling the switching of the gain of the scan signal; When a touch of an operation object is detected when scanning with a scan signal having a small gain, the control means increases the gain of the scan signal.

2. The electronic device according to claim 1 , wherein the detecting means detects a touch of the operation object based on a plurality of measurement results of the measuring means.

3. the detecting means further includes a calculating means for calculating coordinates of a touch position of an operation target based on the capacitances of the plurality of points measured by the measuring means; The electronic device according to claim 1 , wherein the calculation means calculates the coordinates of the touch position of the operation target based on a measurement result obtained when scanning is performed using a scan signal with a large gain.

4. The electronic device according to claim 1 , wherein the operation object is a worn glove, a mitten, or an equivalent thereof.

5. A touch detection method for an electronic device equipped with a capacitive touch panel, comprising: detecting a touch of an operation object based on capacitance measured when the touch panel is scanned with a scan signal of a first gain; In response to detection of a touch of an operation object, calculating coordinates of a touch position of the operation object based on capacitance measured when the touch panel is scanned with a scan signal having a second gain greater than the first gain; A touch detection method including:

6. The touch detection method according to claim 5 , further comprising: switching from a scan signal with a first gain to a scan signal with a second gain when a touch of the operation object is detected.

7. The touch detection method according to claim 5 , wherein the operation object is a worn glove, a mitten, or an equivalent thereof.

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