Touch Panel Device and Touch Panel System

Abstract

The touch panel device (200) includes a touch panel (100) having a touch sensor with a capacitive sensor electrode, and a controller (22) that controls the touch panel (100). When there is contact with a first position by a user on the touch panel (100), the controller (22) has a detection function (221) for detecting adhesion of liquid to the touch panel (100), a calculation function (223) for calculating the conductivity of the adhered liquid based on measurement results of capacitance at a plurality of first detection frequencies when adhesion of liquid is detected by the detection function (221), a determination function (224) for determining a second detection frequency for deriving the first position touched on the touch panel (100) based on the calculated conductivity, and a derivation function (225) for deriving the first position touched by the user using the determined second detection frequency.

Description

Technical Field

[0001] The present disclosure relates to a touch panel device and a touch panel system.

Background Art

[0002] A touch panel is a device that detects a touch by a user's finger or the like and identifies the position coordinates of the touched position. The touch panel has attracted attention as one of the excellent user interfaces. Various types of touch panels, such as the resistive film method and the capacitance method, have been commercialized. Generally, a touch panel includes a touch screen having a built-in touch sensor and a detection device that identifies the position coordinates of the touched position based on a signal from the touch screen.

[0003] As one of the capacitance type touch panels, there is a projected capacitive touch panel. Although the projected capacitive touch panel has high operability, it has a property that it is difficult to accurately detect the touch position when the surface of the touch panel is wet with a liquid such as water droplets. Therefore, in Patent Document 1, when water droplets are present on the touch panel, the frequency of the electrical signal applied to the transmission electrode is increased to accurately detect the touch position on the touch panel where the water droplets are present.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, when the frequency of the electrical signal applied to the transmission electrode (hereinafter referred to as the detection frequency) is higher than a certain value, a decrease in touch detection sensitivity and variations in sensitivity depending on the touched position occur, resulting in a decrease in the operability of the touch panel and the possibility of the occurrence of an inoperable area. This is due to the fact that when the detection frequency is higher than a certain value, the sensor electrode cannot be sufficiently charged, and the entire touch sensor cannot be driven. And this decrease in touch detection sensitivity and variations in sensitivity depending on the touched position become particularly prominent as the touch panel becomes larger and the sensor electrode becomes longer, increasing the capacitance to ground of the sensor electrode itself and increasing the RC product due to the increase in electrical resistance.

[0006] The present disclosure has been made in view of the above, and an object thereof is to obtain a touch panel device capable of accurately detecting a touch coordinate position while minimizing a decrease in touch sensitivity and variations in sensitivity depending on the touched position even when liquid adheres.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, the touch panel device of the present disclosure includes a touch panel having a touch sensor having a capacitive sensor electrode, and a controller that controls the touch panel. The controller includes, in the touch panel, a detection unit that detects the adhesion of liquid to the touch panel when there is contact by a user at a first position, a calculation unit that calculates the conductivity of the adhered liquid based on the measurement results of the capacitance at a plurality of first detection frequencies when the adhesion of liquid is detected by the detection unit, a determination unit that determines a second detection frequency for deriving the first position touched on the touch panel based on the calculated conductivity, and a derivation unit that derives the first position touched by the user using the determined second detection frequency.

Effects of the Invention

[0008] According to the touch panel device of the present disclosure, it is possible to accurately detect the touch coordinate position while minimizing the decrease in touch sensitivity and the variation in sensitivity due to the touched position even when liquid adheres, and thus has the effect described above.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

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Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0010] Hereinafter, a touch panel device and a touch panel system according to an embodiment will be described in detail with reference to the drawings. The drawings are schematic and conceptually explain functions or structures. Also, the present application is not limited by the following embodiments. Unless otherwise specified, the basic configuration of the touch panel device is common to all embodiments. Also, those with the same reference numerals are the same or corresponding thereto, which is common to each embodiment.

[0011] Embodiment 1. The touch panel device according to Embodiment 1 measures capacitance using two or more different detection frequencies. When liquid adhesion is detected, the conductivity of the adhering liquid is calculated using the difference in capacitance values at the same touch sensor position measured at different frequencies, and the detection frequency is adjusted and controlled based on the calculated conductivity. The touch panel device of Embodiment 1 is used, for example, as an input device of a numerical control device that controls automatic machines such as machine tools.

[0012] (Problem) In a machine tool, cutting oil is used during cutting operations. Since a touch panel device installed in such a machine tool may be operated with a hand that has touched the workpiece with cutting oil, a large amount of cutting oil may adhere to the touch panel device via the hand. In addition, since the cutting oil is often a water-soluble one diluted with water, the cutting oil may have a higher conductivity than water due to the conductive ions in the cutting oil. When a conductive liquid adheres to a touch panel device installed in such a machine tool, as described in Patent Document 1, when the detection frequency is low, the liquid behaves as a conductor, so the position of the capacitance change due to finger touch spreads not only to the finger touch point but also to the position wetted with the liquid. Therefore, in order to obtain an accurate touch detection position, it is necessary to increase the detection frequency of the touch panel and use it in a region of the detection frequency where the electrical resistance of the liquid is high and it behaves like an insulator. On the other hand, when the detection frequency is increased, the touch sensitivity decreases because the sensor electrodes cannot be sufficiently charged and discharged. In particular, at a position far from the flexible substrate of the sensor electrode, compared with a position close to the flexible substrate of the sensor electrode, the resistance value from the detection IC (Integrated Circuit) to the touch location is high and the parasitic capacitance is also large, so the sensitivity decrease due to touch becomes large and a touch sensitivity distribution depending on the position occurs. This is because when an electrical signal is applied to the sensor electrode at a high frequency, the sensor electrode cannot be sufficiently charged, and the entire touch sensor cannot be driven. In particular, as the touch panel becomes larger and the sensor electrode becomes longer, the capacitance to ground of the sensor electrode itself increases, and the RC product increases due to the high electrical resistance, resulting in a significant decrease in sensitivity and a sensitivity distribution.

[0013] FIG. 1 is a plan view showing the configuration of a touch panel device 200 including a touch panel 100 and a control board 21 according to Embodiment 1. FIG. 2 is a partial cross-sectional view showing the configuration of the touch panel device 200 according to Embodiment 1. FIG. 2 shows the touch panel device 200 and the display device 30. The display device 30 and the touch panel device 200 constitute a display device with a touch panel.

[0014] The touch panel 100 is provided with a base substrate 8, an interlayer insulating film 9, and a protective film 10 laminated in this order. The display device 30 is disposed to face the touch panel 100 from the side of the base substrate 8.

[0015] For the base substrate 8, due to the necessity that the display device 30 can be visually recognized from the touch panel 100 side, a material such as glass or resin that is transparent or translucent is adopted.

[0016] The touch panel 100 is provided with a receiving electrode 2 and a transmitting electrode 3. The receiving electrode 2 and the transmitting electrode 3 have conductivity and transparency and constitute a touch sensor. The sensor electrode is a general term for the receiving electrode 2 and the transmitting electrode 3. The receiving electrodes 2 are arranged side by side in the vertical direction (hereinafter referred to as the "column direction") on the drawing and are electrically connected to each other in the column direction. The transmitting electrodes 3 are arranged side by side in the horizontal direction (hereinafter referred to as the "row direction") on the drawing and are electrically connected to each other in the row direction. The receiving electrode 2 and the transmitting electrode 3 are insulated from each other.

[0017] Here, the receiving electrode 2 and the transmitting electrode 3 constitute a rhombic lattice arrangement in plan view. Since the receiving electrode 2 and the transmitting electrode 3 that constitute a rhombic lattice arrangement in plan view are well-known, a detailed description thereof will be omitted. Of course, the receiving electrode 2 and the transmitting electrode 3 may constitute an arrangement in other shapes in plan view. In FIG. 1, in order to make it easier to distinguish between the receiving electrode 2 and the transmitting electrode 3, the receiving electrode 2 and the transmitting electrode 3 are hatched with shading.

[0018] The receiving electrode 2 is disposed on the base substrate 8 and covered with the interlayer insulating film 9. The transmitting electrode 3 is disposed on the interlayer insulating film 9 and covered with the protective film 10. Generally, the receiving electrode 2, the transmitting electrode 3, the interlayer insulating film 9, and the protective film 10 are thinner than the lateral scale of the sensor length of the region where the receiving electrode 2 and the transmitting electrode 3 are provided. Therefore, the receiving electrode 2 and the transmitting electrode 3 are provided in a plane parallel to the touch panel 100.

[0019] In the region where the rhombic lattice formed by the receiving electrode 2 and the transmitting electrode 3 is arranged, when a conductor such as a finger or a touch pen comes into contact with the protective film 10, the positions in the row direction and the column direction of the contacted portion can be detected. Also, what is detected here is the position within the plane parallel to the touch panel 100.

[0020] A control board 21 is electrically connected to the touch panel 100 via a flexible printed circuit board 20. The control board 21 includes a controller 22 for controlling the touch panel 100. The controller 22 includes a processing circuit 220. The processing circuit 220 is a processor that functions as the center of the controller 22. The processing circuit 220 realizes the functions corresponding to the executed programs, for example, by executing various programs stored in a storage circuit (not shown). Note that the processing circuit 220 may have a storage area for storing at least a part of the data stored in the storage circuit.

[0021] The processing circuit 220 according to Embodiment 1 realizes various functions by executing the program according to this embodiment. Specifically, the processing circuit 220 realizes a detection function 221, a measurement function 222, a calculation function 223, a determination function 224, a derivation function 225, and an output function 226, for example, by executing a program stored in a storage circuit. The detection function 221 is an example of the detection unit in the claims. The measurement function 222 is an example of the measurement unit in the claims. The calculation function 223 is an example of the calculation unit in the claims. The determination function 224 is an example of the determination unit in the claims. The derivation function 225 is an example of the derivation unit in the claims. The output function 226 is an example of the output unit in the claims.

[0022] When the detection function 221 detects contact with the first position by the user on the touch panel 100, it detects the adhesion of liquid to the touch panel 100. The measurement function 222 applies a voltage to the receiving electrode 2 and the transmitting electrode 3, which are, for example, touch detection wirings, and measures the capacitance obtained from the receiving electrode 2 and the transmitting electrode 3, which are touch detection wirings. When measuring the capacitance, the measurement function 222 uses a plurality of first detection frequencies and a second detection frequency as described later. When the calculation function 223 detects the adhesion of liquid by the detection function 221, it calculates the conductivity of the adhered liquid based on the measurement results of the capacitance at the plurality of first detection frequencies. The determination function 224 determines a second detection frequency for deriving the first position touched on the touch panel 100 based on the calculated conductivity. The derivation function 225 derives the first position touched by the user using the second detection frequency determined by the determination function 224. The output function 226 outputs the first position derived by the derivation function 225 to an external device, for example, a computer.

[0023] In the touch panel 100, both self-capacitance detection and mutual-capacitance detection are used as touch detection methods based on capacitance. In self-capacitance detection, each receiving electrode 2 and each transmitting electrode 3 independently detect the capacitance of each electrode itself. When the user's finger or a conductive object comes close to the receiving electrode 2, the capacitance of the receiving electrode 2 increases, and the touch position is specified using the position of the sensor electrode that detects this and the amount of change in the capacitance value. On the other hand, in mutual-capacitance detection, a change in the capacitance between the receiving electrode 2 and the transmitting electrode 3 is detected. The electric field generated from the transmitting electrode 3 affects the receiving electrode 2, and when the user's finger disturbs this electric field, the mutual capacitance between the transmitting electrode 3 and the receiving electrode 2 decreases. The touch position is specified using the position of the sensor electrode that detects this and the amount of change in the capacitance value.

[0024] (Internal Processing) FIG. 3 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 1. FIG. 3 shows the internal processing of the controller 22 at the time of touch detection. When the detection process is started, the controller 22 performs capacitance measurement (step S1), determination of liquid detection (step S2), calculation of the sheet resistance of the liquid (step S3), determination of whether the sheet resistance is equal to or greater than a certain value (step S4), determination of the detection frequency (step S5), stop of touch coordinate output (step S6), derivation of touch coordinates (step S7), and touch coordinate output (step S8). Hereinafter, each step will be described in detail. Note that the capacitance measurement in step S1 is repeated at regular intervals together with a series of processes in steps S2 to S8.

[0025] In the capacitance measurement in step S1, the measurement function 222 sequentially obtains three types of capacitances by sequentially using three types of frequencies, 50 kHz, 100 kHz, and 200 kHz, as the detection frequencies, which are the frequencies of the electrical signals sent to the transmission electrode 3. The plurality of detection frequencies first used by the measurement function 222 correspond to the first detection frequency. At each detection frequency, an electrical signal in the form of a pulse signal or a sine wave is applied to one of the transmission electrodes 3, and the charge detected at the reception electrode 2 is measured to obtain the mutual capacitance between one of the transmission electrodes 3 and one of the reception electrodes 2 at all the cross points of the electrodes. Further, electrical signals are applied to each of the transmission electrode 3 and the reception electrode 2, and the self-capacitance of each electrode is also measured.

[0026] In step S2, the detection function 221 determines whether a conductive liquid such as water or oil is attached to the touch panel 100. In a normal touch by a user's finger, the mutual capacitance between the receiving electrode 2 and the transmitting electrode 3 decreases. However, when a liquid is attached, a transmission signal is re-emitted to the cross points between other electrodes through the liquid, and thus there may be cross points between electrodes where the mutual capacitance increases. In the detection of liquid attachment in step S2, by utilizing this fact, when simultaneously detecting a decrease in mutual capacitance in a normal touch by a user's finger and an increase in mutual capacitance with a sign opposite thereto in the mutual capacitance between the transmitting electrode 3 and the receiving electrode 2, it is determined that there is liquid attachment (step S2: Yes). If no liquid attachment is detected (step S2: No), the procedure proceeds to step S7.

[0027] Next, in step S3, the calculation function 223 calculates the conductivity of the attached liquid by calculating the sheet resistance of the attached liquid on the touch panel 100. The method will be specifically described below. FIG. 4 is a diagram showing a profile of changes in mutual capacitance measured at each detection frequency on a certain transmitting electrode when a liquid having conductivity adheres to the touch panel device 200 according to Embodiment 1. In FIG. 4, the horizontal axis represents the sensor position, and the vertical axis represents the normalized capacitance change value. FIG. 4 shows the relationship between the change in mutual capacitance measured at three detection frequencies of 50 kHz, 100 kHz, and 200 kHz on a certain transmitting electrode 3 and the sensor position when a liquid having conductivity adheres to the touch panel 100 from the sensor position 0 to the sensor position 21. When the detection frequency is 50 kHz, it is plotted with black circles, when the detection frequency is 100 kHz, it is plotted with triangles, and when the detection frequency is 200 kHz, it is plotted with squares.

[0028] FIG. 5 is a diagram showing the relationship between the pulse period of the electrical signal applied to the transmission electrodes of the touch panel device 200 according to Embodiment 1 and the half-value width of the change in mutual capacitance. Also in FIG. 5, as in FIG. 4, when the detection frequency is 50 kHz, it is plotted with black circles, when the detection frequency is 100 kHz, it is plotted with triangles, and when the detection frequency is 200 kHz, it is plotted with squares. The pulse period is the reciprocal of the detection frequency. Based on the relationship between the change in mutual capacitance and the sensor position shown in FIG. 4, the number of sensor electrodes that becomes the half-value width for the peak that is the touch point at each detection frequency is obtained. The number of sensor electrodes that becomes the half-value width is the number of sensor electrodes included in the half-value width. As shown in FIG. 5, when the half-value width with respect to the peak of the capacitance change value at each detection frequency is plotted on the vertical axis and the pulse period, which is the reciprocal of each detection frequency, is plotted on the horizontal axis, the relationship between the half-value width and the pulse period is nearly linear. When the plotted points are linearly approximated, the slope of the approximate straight line obtained by the least squares method is called the half-value width change rate here. In this way, the half-value width change rate is obtained by measurement at a plurality of detection frequencies. When the sheet resistance of the adhering liquid is high, the adhering liquid behaves close to an insulator during the measurement of capacitance, so the change in the half-value width by changing the pulse period becomes small and the half-value width approaches 1, so the half-value width change rate becomes smaller than the straight line in FIG. 5. On the other hand, when the sheet resistance of the adhering liquid is low, the increase amount of the half-value width increases as the pulse period becomes longer, so the half-value width change rate becomes larger than the straight line in FIG. 5. Thus, the half-value width change rate depends on the sheet resistance of the adhering liquid.

[0029] Inside the calculation function 223, a numerical table of the correlation relationship in which the half-value width change rate and the sheet resistance obtained in this way in advance correspond one-to-one is stored. Or, the calculation function 223 has a function that outputs the sheet resistance when the half-value width change rate is input. The calculation function 223 calculates the sheet resistance of the adhering liquid, that is, the conductivity, by referring to the numerical table or the function from the half-value width change rate obtained by measurement at a plurality of detection frequencies.

[0030] Note that, without using the half-value width, the capacitance change values at the same touch sensor position near the touch position measured at a plurality of detection frequencies (for example, the portion of the thick line K) are obtained based on the profile shown in FIG. 4, and the capacitance change values at the plurality of obtained detection frequencies may be used instead of the half-value width to calculate the sheet resistance, that is, the conductivity of the adhering liquid.

[0031] Next, in step S4, the determination function 224 determines whether the sheet resistance of the adhering liquid is equal to or greater than a certain value as the first threshold value. If the sheet resistance value of the adhering liquid is equal to or greater than the certain value (step S4: Yes), the procedure proceeds to step S5, and based on the obtained sheet resistance, a detection frequency for actually detecting the touch position is determined. The detection frequency derived in this step S5 corresponds to the second detection frequency. For the determination of the detection frequency, a table of sheet resistance and the optimal detection frequency is stored in advance inside the determination function 224, or a function that outputs the optimal detection frequency when the sheet resistance value is input is provided. If the sheet resistance of the adhering liquid is lower than the certain value (step S4: No), the procedure proceeds to step S6, the touch coordinate output is stopped, and the process ends. This is because if the detection frequency is increased too much, a decrease in sensitivity and sensitivity distribution will occur, so the detection frequency is not increased any further.

[0032] In step S7, the derivation function 225 derives the coordinate position touched using the drive voltage of the detection frequency determined in step S5. In the calculation of the coordinate position, the touch coordinates are determined from the peak of the mutual capacitance value at each cross point. Also, a touch determination threshold is set for each of the mutual capacitance method and the self-capacitance method, and the coordinate output is performed only when both touch determination thresholds are exceeded. Here, the touch determination threshold is the threshold at which it is determined that there is a touch by a finger when the capacitance change exceeds the touch determination threshold.

[0033] In step S8, the output function 226 outputs the calculated coordinate position to an external device, for example, a computer. After that, the processing from step S1 to step S8 is repeatedly executed at regular intervals.

[0034] According to the first embodiment as described above, when detecting the adhesion of liquid on the touch panel 100, the conductivity, which is the sheet resistance of the adhered liquid, is calculated based on the measurement results of the capacitance at a plurality of detection frequencies, the detection frequency is determined based on the calculated conductivity, and the touched coordinate position is derived using the determined detection frequency. Therefore, the touched coordinate position can be detected using the optimal detection frequency, and while accurately outputting the touch coordinate position even when liquid adheres, it is possible to minimize the decrease in touch sensitivity and the occurrence of sensitivity distribution.

[0035] Second Embodiment. The touch panel device 200 according to the second embodiment measures the capacitance using two or more detection frequencies. When detecting liquid adhesion, the conductivity of the adhered liquid is calculated using the difference in the capacitance values at the same touch sensor position measured at different frequencies, and based on the calculated conductivity, the detection frequency is determined and the number of touch points or the touch determination threshold value is adjusted and controlled. The configuration of the touch panel 100 according to the second embodiment is the same as FIGS. 1 and 2 of the first embodiment, and duplicate explanations are omitted.

[0036] FIG. 6 is a flowchart showing the operation of the touch panel device 200 according to the second embodiment. In FIG. 6, for the steps having the same step numbers as those in FIG. 3, since they are the same as in the first embodiment, detailed explanations are omitted, and only the differences from the first embodiment will be described.

[0037] First, when the touch panel device 200 starts the touch detection operation, the measurement function 222 measures the capacitance of the sensor electrodes by the self-capacitance method and the mutual-capacitance method (step S1). Next, the detection function 221 determines whether or not liquid is attached to the touch panel 100 from the result of the capacitance measurement (step S2). When liquid is attached (step S2: Yes), the calculation function 223 calculates the sheet resistance of the attached liquid (step S3). When no liquid is attached (step S2: No), the derivation function 225 derives the touch coordinates (step S7). The output function 226 outputs the derived touch coordinates (step S8). Thereafter, the processes from step S1 to step S8 are repeatedly executed at regular intervals.

[0038] After step S3, the determination function 224 determines whether the sheet resistance is equal to or greater than a certain value (step S4). Next, if the sheet resistance value of the adhered liquid is equal to or greater than a certain value as the first threshold (step S4: Yes), the determination function 224 determines that touch coordinates can be output and determines a touch determination threshold (step S25). The touch determination threshold determined at this time increases to a higher level than before the liquid adhesion. Here, the determination function 224 has a function inside that outputs a touch determination threshold when the sheet resistance of the liquid is input, and uses this function to determine the touch determination threshold. The touch determination threshold is set to a function that is inversely proportional to the sheet resistance of the adhered liquid because, for example, the lower the sheet resistance of the adhered liquid, the more necessary it is to increase the touch determination threshold. Thereby, when the sheet resistance of the adhered liquid is low, by increasing the touch determination threshold, it is possible to suppress false detection of touch due to liquid adhesion. When step S25 ends, the determination function 224 shifts the procedure to step S5 and determines a detection frequency for actually detecting the touch position based on the obtained sheet resistance. Next, the derivation function 225 derives the touched coordinate position using the drive voltage of the detection frequency determined in step S5 and the touch determination threshold determined in step S25 (step S7). Next, the output function 226 outputs the calculated coordinate position to an external device, for example, a computer (step S8). After this, the processing from step S1 to step S8 is repeatedly executed at regular intervals.

[0039] Also, in step S25 of FIG. 6, although the determination function 224 increases the touch determination threshold, it may control the number of touch points. The number of touch points is the number of locations on the touch panel 100 that can be simultaneously touched and operated. Specifically, if the sheet resistance value of the adhered liquid is equal to or greater than a certain value (step S4: Yes), it is determined that coordinates can be detected, and the number of touch points may be decreased compared to when no liquid is adhered. For example, if the number of touch points when no liquid is adhered is 10, the number of touch points may be changed to 2 or 1 when liquid is adhered. Also at this time, the detection method may be changed from a detection method that is a combination of the mutual capacitance method and the self-capacitance method to a detection method that is only the self-capacitance method. The detection method that is only the self-capacitance method generally can only detect up to 2 points, but if the liquid is not capacitively coupled to the ground by a finger or the housing, etc., the capacitance change due to liquid adhesion is almost non-existent compared to the mutual capacitance method, so false detection of touch during liquid adhesion can be suppressed.

[0040] FIG. 7 is a flowchart showing other operations of the touch panel device 200 according to Embodiment 2. In FIG. 7, step S4 of FIG. 3 is replaced with step S24’, step S24’’, step S24’’’, and step S25’ and step S25’’ are added, so that multiple steps are passed through when determining the sheet resistance. That is, three thresholds R1, R2, and R3 are defined assuming that the sheet resistance of the adhered liquid is discriminated in three stages. The magnitude relationship of these thresholds is R1 > R2 > R3. Threshold R1 corresponds to the first threshold, threshold R2 corresponds to the second threshold, and threshold R3 corresponds to the third threshold.

[0041] First, the determination function 224 determines whether the sheet resistance of the adhered liquid is equal to or greater than the threshold value R1 (step S24’). If the sheet resistance is equal to or greater than the threshold value R1 (step S24’: Yes), it executes the determination of the detection frequency (step S5). When the sheet resistance of the adhered liquid is less than the threshold value R1 (step S24’: No), the determination function 224 determines whether the sheet resistance of the adhered liquid is equal to or greater than the threshold value R2 (step S24’’). The threshold value R2 is smaller than the threshold value R1. If the sheet resistance of the adhered liquid is equal to or greater than the threshold value R2 (step S24’’: Yes), the determination function 224 limits the number of touch points to a number of touch points less than the number of touch points when no liquid is adhered, for example, 2 points (step S25’). Next, when the sheet resistance of the adhered liquid is less than the threshold value R2 (step S24’’: No), the determination function 224 determines whether the sheet resistance of the adhered liquid is equal to or greater than the threshold value R3 (step S24’’’). The threshold value R3 is smaller than the threshold value R2. If the sheet resistance of the adhered liquid is equal to or greater than the threshold value R3 (step S24’’’: Yes), the determination function 224 increases the touch determination threshold value (step S25’’). When the sheet resistance of the adhered liquid is less than the threshold value R3 (step S24’’’: No), since the risk of false detection by the adhered liquid is considered high even if the detection parameters such as the detection frequency, the touch determination threshold value, or the number of touch points are changed, the touch coordinate output is stopped (step S6). After this, the processing from step S1 to step S8 is repeatedly executed at regular intervals.

[0042] In step S5, the determination function 224 determines the detection frequency from the obtained sheet resistance. In step S7, the derivation function 225 derives the touched coordinate position using the drive voltage of the determined detection frequency. When deriving this coordinate position, if step S24'' is Yes, the number of touch points is limited to two, and if step S24''' is Yes, the touch determination threshold is increased and the number of touch points is limited to two. In step S8, the output function 226 outputs the calculated coordinate position to an external device, such as a computer. After this, the processing from step S1 to step S8 is repeatedly executed at regular intervals. Note that in step S5, the detection frequency may be determined by selecting different numerical tables depending on whether the sheet resistance of the adhering liquid is equal to or greater than the threshold value R1, less than the threshold value R1 and equal to or greater than the threshold value R2, or less than the threshold value R2 and equal to or greater than the threshold value R3. After outputting the touch coordinates, the operation ends.

[0043] Thus, according to Embodiment 2, if the sheet resistance, which is the calculated conductivity, is equal to or greater than a certain value, the touch determination threshold is increased compared to before the liquid adhesion, so the number of touch points decreases and false detection can be suppressed. Also, if the sheet resistance, which is the calculated conductivity, is equal to or greater than a certain value, the number of touch points is decreased compared to before the liquid adhesion, so the number of touch points decreases and false detection can be suppressed. Further, when the calculated sheet resistance, which is the conductivity, is less than the threshold value R1 and equal to or greater than the threshold value R2, the number of touch points is decreased compared to before the liquid adhesion, and when the calculated sheet resistance is less than the threshold value R2 and equal to or greater than the threshold value R3, the touch determination threshold is increased compared to before the liquid adhesion. Therefore, even when the conductivity is less than the threshold value R1 and equal to or greater than the threshold value R3, the number of touch points decreases and false detection can be suppressed.

[0044] Embodiment 3. The touch panel device 200 according to Embodiment 3 measures capacitance using two or more detection frequencies, and changes the detection frequency to a frequency less affected by noise in a noise environment where a common mode is applied to the signal ground of the electric circuit of the control board 21. In the touch panel device 200, when liquid adhesion is detected, the conductivity of the adhered liquid is calculated using the difference in capacitance values at the same touch sensor position measured at the respective detection frequencies after the change, and the detection frequency is adjusted and controlled based on the calculated conductivity. The configuration of the touch panel device 200 according to Embodiment 3 is the same as FIGS. 1 and 2 of Embodiment 1, and redundant descriptions are omitted.

[0045] FIG. 8 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 3. In FIG. 8, for steps having the same step numbers as the step numbers in FIG. 3, since they are the same as those in Embodiment 1, detailed descriptions are omitted, and only the differences from Embodiment 1 are described.

[0046] First, when the process starts, the measurement function 222 executes noise measurement (step S31). In the noise measurement, the amount of change over time within a certain period in the capacitance measured at each of the three initially set detection frequencies is evaluated. When the voltage level of the common-mode noise is large, especially in a noise environment where the noise contains frequency components close to the detection frequency, the amount of change in the measured capacitance becomes large, making it difficult to accurately detect the touch position. Here, the amount of change in capacitance is defined, for example, as the difference between the maximum value and the minimum value of the capacitance measurement values within a certain period. The measurement function 222 determines whether the noise is below a certain value by determining whether this amount of change is below a certain value (step S32). If the measurement function 222 determines that the amount of change is greater than the certain value and the noise is greater than the certain value (step S32: No), the detection frequency is changed and another detection frequency is selected (step S33). After the detection frequency is changed, the process returns to the noise measurement step (step S31) again. The steps from step S31 to step S33 are repeated for all three types of frequencies used as the detection frequency until the amount of change in capacitance becomes below a certain value. As a result, capacitance measurement can be performed at a detection frequency with less noise interference, so false detections and undetected detections due to noise are suppressed, and stable detection of the touch position becomes possible.

[0047] When it is confirmed that the noise is below a certain value at the three types of frequencies used as the detection frequency (step S32: Yes), the processing from step S1 to step S8 is executed in the same manner as in Embodiment 1.

[0048] Thus, according to Embodiment 3, when measuring capacitance, the amount of change in the capacitance measurement value with respect to time is measured, and when the amount of change is greater than a certain value, the detection frequency is changed to another frequency. Therefore, it is possible to suppress false detections when liquid adheres while suppressing a decrease in operability even in a noise environment.

[0049] Embodiment 4. The touch panel device 200 according to Embodiment 4 measures capacitance using two or more detection frequencies, and can determine whether the touch is made with the palm or fingertips even when liquid adheres. When touching the touch panel 100 with liquid adhering, when liquid adhesion is detected, the conductivity of the adhering liquid is calculated using the difference in capacitance values at the same touch sensor position measured at different frequencies in the same manner as in Embodiment 1, and the detection frequency is adjusted and controlled based on the calculated conductivity. Further, by counting the number of cross points of sensor electrodes where the capacitance change is equal to or greater than the touch determination threshold value at the palm detection frequency for palm determination, the touch by the palm and finger is discriminated. The configuration of the touch panel device 200 according to Embodiment 4 is the same as FIGS. 1 and 2 of Embodiment 1, and redundant explanations are omitted.

[0050] FIG. 9 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 4. In FIG. 9, for the steps having the same step numbers as those in FIG. 3, since they are the same as in Embodiment 1, detailed explanations are omitted, and only the points different from Embodiment 1 will be described.

[0051] The processing from step S1 to step S5 is the same as in Embodiment 1. When the detection frequency is determined (step S5), the determination function 224 determines a frequency higher than the determined detection frequency as the palm detection frequency (step S41).

[0052] Next, the determination function 224 compares the number of cross points of sensor electrodes where the capacitance change value measured at the palm detection frequency is equal to or greater than the touch determination threshold value with a fixed number (step S42). As a result of this comparison, when the number of cross points is greater than the fixed number (step S42: No), the touch coordinate output is stopped (step S6). This is because when the touch panel 100 is touched with the palm instead of the finger, the number of cross points of sensor electrodes where the capacitance change value is equal to or greater than the touch determination threshold value at the palm detection frequency higher than the detection frequency is greater than the fixed number. In such a case, the determination function 224 determines that the touch panel 100 is touched with the palm and stops the touch coordinate output.

[0053] On the other hand, if the number of cross points is equal to or less than a certain number as a result of the comparison in step S42 (step S42: Yes), the determination function 224 determines that it is a touch by a finger. Next, the derivation function 225 derives the touch coordinates based on the capacitance value measured using the detection frequency determined in step S5 (step S7). The output function 226 outputs the calculated coordinate position to an external device such as a computer (step S8). After that, the processes from step S1 to step S8 are repeatedly executed at regular intervals.

[0054] In step S42, the determination function 224 compares the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value in the capacitance value measured at the detection frequency with the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value in the capacitance value measured at the palm detection frequency, and may shift the process to either step S6 or S7 based on this comparison result. Since the palm detection frequency is higher than the detection frequency, when the cross points of the sensor electrodes whose capacitance changes due to the attached liquid in the case of a touch by a finger are spread, the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value is smaller when measured at the palm detection frequency than when measured at the detection frequency. On the other hand, in the case of a touch by a palm, the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value does not change between when measured at the palm detection frequency and when measured at the detection frequency. For this reason, if the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value when measured at the palm detection frequency is less than a certain number or more than the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value when measured at the detection frequency, it is determined that it is a touch by a finger. On the other hand, if the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value when measured at the palm detection frequency is approximately the same as the number of cross points of the sensor electrodes equal to or greater than the touch determination threshold value when measured at the detection frequency, it is determined that it is a touch by a palm.

[0055] As described above, according to the fourth embodiment, it is possible to distinguish between a palm and a finger even when liquid adheres, and the operability can be improved.

[0056] Embodiment 5. FIG. 10 is a conceptual diagram showing the configuration of a touch panel system 300 according to Embodiment 5. The touch panel system 300 shown in FIG. 10 includes a touch panel device 200 and a numerical control device 14 to which the touch panel device 200 is connected. The touch panel device 200 may be any of the touch panel devices 200 of Embodiments 1 to 4. The numerical control device 14 is a computer that controls the machining of a workpiece by a tool while relatively moving the workpiece and the tool attached to a machine tool.

[0057] The numerical control device 14 has at least some of the functions of the above-described detection function 221, measurement function 222, calculation function 223, determination function 224, derivation function 225, and output function 226 of the processing circuit 220, and drives and controls the touch panel 100 in cooperation with the processing circuit 220 and the numerical control device 14. For example, by processing a signal from the touch panel 100 by software of a programmable controller unit of the numerical control device 14, at least some of the above functions of the processing circuit 220 are realized.

[0058] The configurations shown in the above embodiments are examples of the content of the present disclosure, and it is possible to combine them with other known technologies, combine the embodiments with each other, and omit or change a part of the configuration without departing from the gist of the present disclosure.

Explanation of Reference Numerals

[0059] 2 receiving electrode, 3 transmitting electrode, 8 base substrate, 9 interlayer insulating film, 10 protective film, 14 numerical control device, 20 flexible printed circuit board, 21 control board, 22 controller, 30 display device, 100 touch panel, 200 touch panel device, 220 processing circuit, 221 detection function, 222 measurement function, 223 calculation function, 224 determination function, 225 derivation function, 226 output function, 300 touch panel system.

Claims

1. A touch panel having a touch sensor with a capacitive sensor electrode, and a controller for controlling the touch panel, wherein the controller in the touch panel, when there is contact with a first position by a user, a detection unit for detecting adhesion of a liquid to the touch panel; a calculation unit for calculating the conductivity of the adhering liquid based on measurement results of capacitance at a plurality of first detection frequencies when the adhesion of the liquid is detected by the detection unit; a determination unit for determining a second detection frequency for deriving the first position touched on the touch panel based on the calculated conductivity; a derivation unit for deriving the first position touched by the user using the determined second detection frequency; and has A touch panel device characterized by the above.

2. Further comprising an output unit for outputting the first position derived by the derivation unit to an external device The touch panel device according to claim 1, characterized in that.

3. The calculation unit calculates the conductivity of the adhering liquid using a difference in capacitance values at the same touch sensor position measured at a plurality of the first detection frequencies The touch panel device according to claim 1, characterized in that.

4. The calculation unit obtains the relationship between the half-value width of the peak, which is the touch point, and the pulse period of the electrical signal applied to the sensor electrode based on the correspondence between the touch sensor position measured at a plurality of the first detection frequencies and the change in capacitance, and calculates the conductivity of the adhering liquid based on the relationship. The touch panel device according to claim 1, characterized in that.

5. The determination unit if the calculated conductivity is equal to or greater than a first threshold value, determines the second detection frequency based on the calculated conductivity; if the calculated conductivity is less than the first threshold value, stops outputting the touched coordinate position The touch panel device according to any one of claims 1 to 4, characterized in that.

6. The determination unit if the calculated conductivity is equal to or greater than the first threshold value, increases a touch determination threshold value, which is a threshold value for determining that there is a touch by a finger due to a change in capacitance, compared to before the liquid adhesion. The touch panel device according to claim 5, characterized in that.

7. The determination unit If the calculated conductivity is greater than or equal to the first threshold value, the number of touch points, which is the number of locations that can be touched and operated simultaneously on the touch panel, is reduced compared to before the liquid adhesion. The touch panel device according to claim 5, characterized in that.

8. The determination unit If the calculated conductivity is greater than or equal to the first threshold value, the second detection frequency is determined based on the calculated conductivity. If the calculated conductivity is less than the first threshold value and greater than or equal to a second threshold value smaller than the first threshold value, the number of touch points, which is the number of locations that can be touched and operated simultaneously on the touch panel, is reduced compared to before the liquid adhesion, and the second detection frequency is determined based on the calculated conductivity. If the calculated conductivity is less than the second threshold value and greater than or equal to a third threshold value smaller than the second threshold value, the touch determination threshold, which is a threshold for determining that there is a touch by a finger due to a change in capacitance, is increased compared to before the liquid adhesion, and the second detection frequency is determined based on the calculated conductivity. The touch panel device according to claim 5, characterized in that.

9. The controller When measuring the capacitance, further includes a measurement unit that measures the amount of variation of the capacitance measurement value with respect to time, and when the amount of variation is greater than a certain value, changes the first detection frequency to another frequency. The touch panel device according to any one of claims 1 to 4, characterized in that.

10. The determination unit If the number of cross points of the sensor electrodes where the capacitance change measured at the detection frequency for hand touch, which is higher than the plurality of first detection frequencies, is greater than a certain number and is greater than or equal to the touch determination threshold, which is a threshold for determining that there is a touch by a finger due to a change in capacitance, it is determined as a hand touch. The touch panel device according to any one of claims 1 to 4, characterized in that.

11. A touch panel having a touch sensor with a capacitive sensor electrode, In the touch panel, a detection unit that detects the adhesion of liquid to the touch panel when there is contact with a first position by a user, A calculation unit that calculates the conductivity of the adhered liquid based on the measurement results of the capacitance at a plurality of first detection frequencies when the adhesion of the liquid is detected by the detection unit, A determination unit that determines a second detection frequency for deriving the first position contacted on the touch panel based on the calculated conductivity. A derivation unit that derives the first position touched by the user using the determined second detection frequency; having A touch panel system characterized by this.

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