Touch panel device and touch panel system

Abstract

A touch panel device (200) comprises: a touch panel (100) that has a touch sensor having a capacitive sensor electrode; and a controller (22) that controls the touch panel (100). The controller (22) has: a detection function (221) for detecting adhesion of a liquid to the touch panel (100) when a user has touched a first position on the touch panel (100); a calculation function (223) for, when the adhesion of the liquid has been detected by the detection function (221), calculating the conductivity of the adhered liquid on the basis of the results of measuring capacitance at a plurality of first detection frequencies; a determination function (224) for determining, on the basis of the calculated conductivity, a second detection frequency for deriving the first position touched on the touch panel (100); and a derivation function (225) for using the determined second detection frequency to derive the first position touched by the user.

Description

Touch Panel Device and Touch Panel System

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

[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 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 has a touch screen incorporating a 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 type of capacitive touch panel, there is a projected capacitive touch panel. Although the projected capacitive touch panel has high operability, it has the 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.

[0004] International Publication No. 2017 / 170224

[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 a variation in sensitivity depending on the touched position occur, resulting in a decrease in the operability of the touch panel and a possibility of generating an inoperable region. This is because 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 variation in sensitivity depending on the touched position become more 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] This disclosure has been made in view of the above, and aims to provide a touch panel device that can accurately detect the touch coordinate position while minimizing the decrease in touch sensitivity and the occurrence of variations in sensitivity depending on the touch position, even when liquid is present.

[0007] To solve the above-mentioned problems and achieve the objective, the touch panel device of this disclosure comprises a touch panel having a touch sensor having a capacitive sensor electrode, and a controller for controlling the touch panel. The controller includes, on the touch panel, a detection unit that detects the adhesion of liquid to the touch panel when a user makes contact with a first position, a calculation unit that calculates the conductivity of the adhered liquid based on the capacitance measurement results at a plurality of first detection frequencies when the detection unit detects the adhesion of liquid, a determination unit that determines a second detection frequency for deriving the first position that was touched on the touch panel based on the calculated conductivity, and a derivation unit that derives the first position that was touched by the user using the determined second detection frequency.

[0008] The touch panel device of this disclosure has the effect of enabling accurate detection of the touch coordinate position while minimizing the decrease in touch sensitivity and the occurrence of variations in sensitivity depending on the touch location, even when liquid is present.

[0009] A plan view showing the configuration of a touch panel device including a touch panel and control board according to Embodiment 1. A partial cross-sectional view showing the configuration of a touch panel device according to Embodiment 1. A flowchart showing the operation of a touch panel device according to Embodiment 1. A diagram showing the profile of the change in mutual capacitance measured at each detection frequency on a certain transmitting electrode when a conductive liquid adheres to the touch panel device according to Embodiment 1. A diagram showing the relationship between the pulse period of the electrical signal applied to the transmitting electrode of the touch panel device according to Embodiment 1 and the half-width of the change in mutual capacitance. A flowchart showing the operation of a touch panel device according to Embodiment 2. A flowchart showing other operations of the touch panel device according to Embodiment 2. A flowchart showing the operation of a touch panel device according to Embodiment 3. A flowchart showing the operation of a touch panel device according to Embodiment 4. A conceptual diagram showing the configuration of a touch system according to Embodiment 5.

[0010] The following describes in detail the touch panel device and touch panel system according to the embodiments, based on the drawings. The drawings are schematic and conceptually illustrate the function or structure. Furthermore, the present application is not limited to the embodiments shown below. Unless otherwise specified, the basic configuration of the touch panel device is common to all embodiments. Also, parts with the same reference numerals are the same or equivalent, and this is common to all embodiments.

[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 device calculates the conductivity of the adhered liquid using the difference in capacitance values ​​at the same touch sensor position measured at different frequencies, and adjusts and controls the detection frequency based on the calculated conductivity. The touch panel device of Embodiment 1 can be used, for example, as an input device for a numerical control device that controls an automated machine such as a machine tool.

[0012] (Problem) Machine tools use cutting fluid during cutting operations. Touch panel devices installed on such machine tools may be operated with hands that have touched the workpiece contaminated with cutting fluid, resulting in a large amount of cutting fluid adhering to the touch panel device via the hands. Furthermore, since cutting fluid is often a water-soluble substance diluted with water, the conductive ions in the cutting fluid can give it a higher conductivity than water. When a conductive liquid adheres to a touch panel device installed on such a machine tool, as described in Patent Document 1, if the detection frequency is low, the liquid behaves as a conductor, so the location of the capacitance change caused by finger touch spreads not only to the point of touch but also to the area wet with the liquid. For this reason, 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 the detection frequency range where the electrical resistance of the liquid is high and it behaves like an insulator. On the other hand, increasing the detection frequency causes a decrease in touch sensitivity because the sensor electrodes cannot be sufficiently charged and discharged. In particular, at positions far from the flexible substrate of the sensor electrode, the resistance value from the detection IC (Integrated Circuit) to the touch point is higher and the parasitic capacitance is also larger compared to positions close to the flexible substrate of the sensor electrode, resulting in a greater decrease in sensitivity due to touch and a distribution of touch sensitivity depending on the position. This is because at high frequencies, when an electrical signal is applied to the sensor electrode, it is not possible to sufficiently charge the sensor electrode and drive the entire touch sensor. In particular, as touch panels become larger and the sensor electrodes become longer, the capacitance to ground of the sensor electrode itself increases, and the electrical resistance also increases, leading to a larger RC product, which in turn causes a decrease in sensitivity and a more pronounced sensitivity distribution.

[0013] Figure 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. Figure 2 is a partial cross-sectional view showing the configuration of the touch panel device 200 according to Embodiment 1. Figure 2 shows the touch panel device 200 and a 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 stacked in that order. The display device 30 is positioned facing the touch panel 100 from the side of the base substrate 8.

[0015] The base substrate 8 is made of a transparent or light-transmitting material, such as glass or resin, because the display device 30 needs to be visible from the touch panel 100 side.

[0016] The touch panel 100 is equipped with receiving electrodes 2 and transmitting electrodes 3. The receiving electrodes 2 and transmitting electrodes 3 are conductive and transparent, and constitute a touch sensor. The term "sensor electrodes" is a collective term for the receiving electrodes 2 and transmitting electrodes 3. The receiving electrodes 2 are arranged in the vertical direction on the drawing (hereinafter referred to as the "column direction") and are electrically conductive to each other in the column direction. The transmitting electrodes 3 are arranged in the horizontal direction on the drawing (hereinafter referred to as the "row direction") and are electrically conductive to each other in the row direction. The receiving electrodes 2 and transmitting electrodes 3 are insulated from each other.

[0017] Here, the receiving electrode 2 and the transmitting electrode 3 form a rhombic grid arrangement in plan view. Since the receiving electrode 2 and transmitting electrode 3 forming a rhombic grid arrangement in plan view are well known, a detailed explanation is omitted. Of course, the receiving electrode 2 and transmitting electrode 3 may be arranged in other shapes in plan view. In Figure 1, the receiving electrode 2 and transmitting electrode 3 are hatched with varying shades of gray to make them easier to distinguish from each other.

[0018] The receiving electrode 2 is placed on the base substrate 8 and covered with an interlayer insulating film 9. The transmitting electrode 3 is placed on the interlayer insulating film 9 and covered with a protective film 10. Generally, the receiving electrode 2, the transmitting electrode 3, the interlayer insulating film 9, and the protective film 10 are thin compared to the lateral scale of the sensor length in the area 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 grid formed by the receiving electrode 2 and the transmitting electrode 3 is arranged, when a conductor such as a finger or a stylus comes into contact with the protective film 10, the position of the contact point in the row and column directions can be detected. Furthermore, the position detected here is within a 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 central hub of the controller 22. The processing circuit 220 realizes functions corresponding to the executed program by executing various programs stored in a memory circuit (not shown), for example. The processing circuit 220 may also have a memory area that stores at least a portion of the data stored in the memory 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 by executing a program stored in the memory circuit, for example. The detection function 221 is an example of the detection unit in the claim. The measurement function 222 is an example of the measurement unit in the claim. The calculation function 223 is an example of the calculation unit in the claim. The determination function 224 is an example of the determination unit in the claim. The derivation function 225 is an example of the derivation unit in the claim. The output function 226 is an example of the output unit in the claim.

[0022] The detection function 221 detects the presence of liquid on the touch panel 100 when a user makes contact with a first position on the touch panel 100. The measurement function 222 applies a voltage to, for example, the receiving electrode 2 and transmitting electrode 3, which are contact detection wiring, and measures the capacitance obtained from the receiving electrode 2 and transmitting electrode 3, which are contact detection wiring. When measuring capacitance, the measurement function 222 uses a plurality of first detection frequencies and a second detection frequency, as will be described later. The calculation function 223 calculates the conductivity of the attached liquid based on the capacitance measurement results at the plurality of first detection frequencies when the detection function 221 detects the presence of liquid. The determination function 224 determines a second detection frequency for deriving the first position that was touched on the touch panel 100 based on the calculated conductivity. The derivation function 225 derives the first position that was 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, such as a computer.

[0023] The touch panel 100 utilizes both self-capacitance detection and mutual capacitance detection 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 the electrode itself. When a user's finger or a conductive object comes near the receiving electrode 2, the capacitance of the receiving electrode 2 increases, and the touch position is determined by using the position of the sensor electrode that detects this change and the amount of change in capacitance value. On the other hand, mutual capacitance detection detects the change in capacitance between the receiving electrode 2 and the transmitting electrode 3. The electric field generated from the transmitting electrode 3 affects the receiving electrode 2, and the user's finger disturbs this electric field, causing the mutual capacitance between the transmitting electrode 3 and the receiving electrode 2 to decrease. The touch position is determined by using the position of the sensor electrode that detects this change and the amount of change in capacitance value.

[0024] (Internal Processing) Figure 3 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 1. Figure 3 shows the internal processing of the controller 22 when a touch is detected. When the detection process starts, the controller 22 performs the following processes: volume 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 above 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 output of touch coordinates (step S8). The following describes each step in detail. Note that the volume measurement in step S1 is repeated at regular intervals along with the series of processes from steps S2 to S8.

[0025] In the capacitance measurement of step S1, the measurement function 222 sequentially uses three types of frequencies, 50 kHz, 100 kHz, and 200 kHz, as detection frequencies, which are the frequencies of the electrical signals sent to the transmitting electrode 3, to sequentially obtain three types of capacitance. The first set of detection frequencies used by the measurement function 222 corresponds to the first detection frequency. At each detection frequency, an electrical signal, either a pulse signal or a sinusoidal signal, is applied to one of the transmitting electrodes 3, and the charge detected at the receiving electrode 2 is measured to determine the mutual capacitance between one of the transmitting electrodes 3 and one of the receiving electrodes 2 at the crossover point of all electrodes. Furthermore, an electrical signal is applied to each of the transmitting electrode 3 and the receiving electrode 2 to measure the self-capacitance of each electrode.

[0026] In step S2, the detection function 221 determines whether or not a conductive liquid such as water or oil is present on the touch panel 100. With a normal touch by a user's finger, the mutual capacitance between the receiving electrode 2 and the transmitting electrode 3 decreases. However, when liquid is present, the transmission signal is re-emitted through the liquid to the crossing point between other electrodes, which may create a crossing point between electrodes where the mutual capacitance increases. In detecting liquid presence in step S2, this is used to determine that liquid is present (step S2: Yes) if both a decrease in mutual capacitance with a normal touch by a user's finger and an increase in mutual capacitance with the opposite sign are detected simultaneously in the mutual capacitance between the transmitting electrode 3 and the receiving electrode 2. If no liquid presence 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 is described in detail below. Figure 4 is a diagram showing the profile of the change in mutual capacitance measured at each detection frequency on a certain transmitting electrode when a conductive liquid is attached to the touch panel device 200 according to Embodiment 1. In Figure 4, the horizontal axis is the sensor position and the vertical axis is the normalized capacitance change value. Figure 4 shows the relationship between the change in mutual capacitance measured at three different detection frequencies, 50 kHz, 100 kHz, and 200 kHz, on a certain transmitting electrode 3 when a conductive liquid is attached to the touch panel 100 from sensor position 0 to sensor position 21, and the sensor position. When the detection frequency is 50 kHz, it is plotted as a black circle, when the detection frequency is 100 kHz, it is plotted as a triangle, and when the detection frequency is 200 kHz, it is plotted as a square.

[0028] Figure 5 shows the relationship between the pulse period of the electrical signal applied to the transmitting electrode of the touch panel device 200 according to Embodiment 1 and the full width at half maximum (FWHM) of the change in mutual capacitance. In Figure 5, as in Figure 4, when the detection frequency is 50 kHz, it is plotted as a black circle, when the detection frequency is 100 kHz, it is plotted as a triangle, and when the detection frequency is 200 kHz, it is plotted as a square. 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 Figure 4, the number of sensor electrodes that make up the FWHM with respect to the peak, which is the touch point, at each detection frequency is obtained. The number of sensor electrodes that make up the FWHM is the number of sensor electrodes included in the FWHM. As shown in Figure 5, when the FWHM 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 FWHM and the pulse period is close to a straight line. When the plotted points are approximated by a straight line, the slope of the approximate straight line obtained by the least squares method is called the FWHM change rate. In this way, the rate of change of full width at half maximum (FWHM) is obtained by measurement using multiple detection frequencies. When the sheet resistance of the attached liquid is high, the attached liquid behaves similarly to an insulator when measuring capacitance, so the change in FWHM due to changing the pulse period becomes small, and the FWHM approaches 1, so the rate of change of FWHM becomes smaller than the straight line in Figure 5. On the other hand, when the sheet resistance of the attached liquid is low, the amount of increase in FWHM increases as the pulse period becomes longer, so the rate of change of FWHM becomes larger than the straight line in Figure 5. Thus, the rate of change of FWHM depends on the sheet resistance of the attached liquid.

[0029] Internally, the calculation function 223 stores a numerical table showing the one-to-one correlation between the rate of change at half maximum (FWHM) and the sheet resistance, which has been acquired in advance in this manner. Alternatively, the calculation function 223 may have a function that outputs the sheet resistance when the rate of change at half maximum is input. The calculation function 223 calculates the sheet resistance, i.e., conductivity, of the adhering liquid by referring to the numerical table or function from the rate of change at half maximum obtained by measurements at multiple detection frequencies.

[0030] Alternatively, instead of using the full width at half maximum, the capacitance change values ​​at the same touch sensor position near the touch position (for example, the part indicated by the thick line K) measured at multiple detection frequencies may be obtained based on the profile shown in Figure 4, and the sheet resistance, i.e., conductivity, of the attached liquid may be calculated by using the obtained capacitance change values ​​at multiple detection frequencies instead of the full width at half maximum.

[0031] Next, in step S4, the determination function 224 determines whether the sheet resistance of the adhering liquid is above a certain value, which is the first threshold. If the sheet resistance of the adhering liquid is above a certain value (step S4: Yes), the procedure moves to step S5, and the detection frequency for actually detecting the touch position is determined based on the obtained sheet resistance. The detection frequency derived in step S5 corresponds to the second detection frequency. To determine the detection frequency, the determination function 224 either has a table of sheet resistance and optimal detection frequency stored internally, or it has a function that outputs the optimal detection frequency when a sheet resistance value is input. If the sheet resistance of the adhering liquid is below a certain value (step S4: No), the procedure moves to step S6, the touch coordinate output is stopped, and the process is terminated. This is because if the detection frequency is made too high, a decrease in sensitivity and a sensitivity distribution will occur, so the detection frequency is not increased any further.

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

[0033] In step S8, the output function 226 outputs the calculated coordinate position to an external device, such as a computer. After this, the processes from step S1 to step S8 are repeatedly executed at regular intervals.

[0034] As described above, according to Embodiment 1, when liquid adhesion on the touch panel 100 is detected, the conductivity, which is the sheet resistance of the adhered liquid, is calculated based on the capacitance measurement results at multiple detection frequencies. Based on the calculated conductivity, the detection frequency is determined, and the touched coordinate position is derived using the determined detection frequency. This allows the touched coordinate position to be detected using the optimal detection frequency, enabling accurate output of the touch coordinate position even when liquid is present, while minimizing the decrease in touch sensitivity and the occurrence of sensitivity distribution.

[0035] Embodiment 2. The touch panel device 200 according to Embodiment 2 measures capacitance using two or more detection frequencies. 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 different frequencies. Based on the calculated conductivity, the detection frequency is determined, and the number of touch points or touch judgment threshold is adjusted and controlled. The configuration of the touch panel 100 according to Embodiment 2 is the same as in Figures 1 and 2 of Embodiment 1, and redundant explanations are omitted.

[0036] Figure 6 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 2. In Figure 6, steps having the same step numbers as in Figure 3 are the same as in Embodiment 1, so a detailed explanation is omitted, and only the differences from Embodiment 1 will be explained.

[0037] First, when the touch panel device 200 starts touch detection, the measurement function 222 measures the capacitance of the sensor electrode using the self-capacitance method and the mutual capacitance method (step S1). Next, the detection function 221 determines from the result of the capacitance measurement whether or not liquid is attached to the touch panel 100 (step S2). If liquid is attached (step S2: Yes), the calculation function 223 calculates the sheet resistance of the attached liquid (step S3). If liquid is not 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). After this, 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 above a certain value (step S4). Next, if the sheet resistance value of the adhering liquid is above a certain value as the first threshold (step S4: Yes), the determination function 224 determines that touch coordinate output is possible and determines the touch detection threshold (step S25). The touch detection threshold determined at this time is increased to a higher level than before the liquid adhered. Here, the determination function 224 has an internal function that outputs a touch detection threshold when the sheet resistance of the liquid is input, and uses this function to determine the touch detection threshold. For example, the touch detection threshold needs to be increased as the sheet resistance of the adhering liquid decreases, so a function is set in which the touch detection threshold is inversely proportional to the sheet resistance of the adhering liquid. This makes it possible to suppress false detection of touch due to liquid adhesion by increasing the touch detection threshold when the sheet resistance of the adhering liquid is low. When step S25 is completed, the determination function 224 moves on to step S5 and determines the 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 judgment threshold determined in step S25 (step S7). Next, the output function 226 outputs the calculated coordinate position to an external device, such as a computer (step S8). After this, the processes from step S1 to step S8 are repeatedly executed at regular intervals.

[0039] Furthermore, in step S25 of Figure 6, the decision function 224 increased the touch detection threshold, but it may also control the number of touch points. The number of touch points is the number of locations on the touch panel 100 that can be touched and operated simultaneously. Specifically, if the sheet resistance value of the attached liquid is above a certain value (step S4: Yes), it may be determined that coordinate detection is possible, and the number of touch points may be reduced compared to when no liquid is attached. For example, if the number of touch points is 10 when no liquid is attached, it may be changed to 2 or 1 when liquid is attached. Also, in this case, the detection method may be changed from a detection method that combines the mutual capacitance method and the self-capacitance method to a detection method that uses only the self-capacitance method. A detection method using only the self-capacitance method can generally only detect up to 2 points, but if the liquid is not capacitively coupled to the ground by a finger or housing, the change in capacitance due to liquid attachment is almost negligible, unlike the mutual capacitance method, so false detection of touches when liquid is attached can be suppressed.

[0040] Figure 7 is a flowchart showing other operations of the touch panel device 200 according to Embodiment 2. In Figure 7, step S4 in Figure 3 is replaced with steps S24', S24'', and S24''', and steps S25' and S25'' are added, so that the sheet resistance determination involves multiple steps. That is, three thresholds R1, R2, and R3 are defined to determine the sheet resistance of the adhering liquid in three stages. The relationship between 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 attached liquid is greater than or equal to the threshold R1 (step S24'). If the sheet resistance is greater than or equal to the threshold R1 (step S24': Yes), it performs the determination of the detection frequency (step S5). If the sheet resistance of the attached liquid is less than the threshold R1 (step S24': No), the determination function 224 determines whether the sheet resistance of the attached liquid is greater than or equal to the threshold R2 (step S24''). Threshold R2 is smaller than threshold R1. If the sheet resistance of the attached liquid is greater than or equal to the threshold R2 (step S24'': Yes), the determination function 224 limits the number of touch points to a number that is less than the number of touch points when no liquid is attached, for example, 2 points (step S25'). Next, if the sheet resistance of the attached liquid is less than the threshold R2 (step S24'': No), the determination function 224 determines whether the sheet resistance of the attached liquid is greater than or equal to the threshold R3 (step S24''''). Threshold R3 is smaller than threshold R2. The determination function 224 increases the touch detection threshold (step S25'') if the sheet resistance of the adhering liquid is greater than or equal to the threshold R3 (step S24''': Yes). If the sheet resistance of the adhering liquid is less than the threshold R3 (step S24''': No), the determination function 224 stops outputting the touch coordinates (step S6) because it is considered that there is a high risk of false detection due to the adhering liquid even if detection parameters such as the detection frequency, touch detection threshold, or number of touch points are changed. After this, the processes from step S1 to step S8 are 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 2, and if step S24''' is Yes, the touch judgment threshold is increased and the number of touch points is limited to 2. In step S8, the output function 226 outputs the calculated coordinate position to an external device, such as a computer. After this, the processes from step S1 to step S8 are 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 attached liquid is greater than or equal to threshold R1, less than threshold R1 and greater than or equal to threshold R2, or less than threshold R2 and greater than or equal to threshold R3. After outputting the touch coordinates, the operation ends.

[0043] As described above, according to Embodiment 2, if the sheet resistance, which is the calculated conductivity, is above a certain value, the touch detection threshold is increased compared to before liquid adhesion, so the number of touch points is reduced and false detections can be suppressed. Also, if the sheet resistance, which is the calculated conductivity, is above a certain value, the number of touch points is reduced compared to before liquid adhesion, so the number of touch points is reduced and false detections can be suppressed. Furthermore, if the sheet resistance, which is the calculated conductivity, is less than threshold R1 and greater than or equal to threshold R2, the number of touch points is reduced compared to before liquid adhesion, and if the sheet resistance is less than threshold R2 and greater than or equal to threshold R3, the touch detection threshold is increased compared to before liquid adhesion, so even when the conductivity is less than threshold R1 and greater than or equal to threshold R3, the number of touch points is reduced and false detections 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 changed detection frequencies, 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 the 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 performs noise measurement (step S31). In the noise measurement, the time-series variation amount within a certain time 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 measured variation amount of the capacitance becomes large, making it difficult to accurately detect the touch position. Here, the variation amount of the capacitance is defined, for example, as the difference between the maximum value and the minimum value of the capacitance measurement values within a certain time. The measurement function 222 determines whether the noise is below a certain value by determining whether this variation amount is below a certain value (step S32). When the measurement function 222 determines that the variation amount is larger than a certain value and the noise is larger than a certain value (step S32: No), the detection frequency is changed to select another detection frequency (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 variation amount of the 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 caused by noise are suppressed, and stable detection of the touch position becomes possible.

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

[0048] Thus, according to Embodiment 3, when measuring the capacitance, the variation amount of the capacitance measurement value with respect to time is measured, and when the variation amount is larger than a certain value, the detection frequency is changed to another frequency. Therefore, it is possible to suppress false detections during liquid adhesion 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 distinguish between palm and fingertip touches even when liquid is present. When touching the touch panel 100 with liquid present, upon detecting the liquid, the conductivity of the attached liquid is calculated using the difference in capacitance values ​​at the same touch sensor position measured at different frequencies, similar to Embodiment 1, and the detection frequency is adjusted and controlled based on the calculated conductivity. Furthermore, the number of crossover points of sensor electrodes where the capacitance change is greater than or equal to the touch detection threshold is counted using the palm detection frequency for hand touch detection, thereby distinguishing between palm and finger touches. The configuration of the touch panel device 200 according to Embodiment 4 is the same as in Figures 1 and 2 of Embodiment 1, and redundant explanations are omitted.

[0050] Figure 9 is a flowchart showing the operation of the touch panel device 200 according to Embodiment 4. In Figure 9, steps having the same step numbers as in Figure 3 are the same as in Embodiment 1, so a detailed explanation is omitted, and only the differences from Embodiment 1 will be explained.

[0051] The processing from step S1 to step S5 is the same as in Embodiment 1. Once the detection frequency is determined (step S5), the determination function 224 determines a frequency even 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 whose capacitance change value is above the touch judgment threshold at the palm detection frequency with a certain number (step S42). If the number of cross points is greater than the certain number (step S42: No), the touch coordinate output is stopped (step S6). This is because if the touch on the touch panel 100 is made by the palm and not a finger, the number of cross points of sensor electrodes whose capacitance change value is above the touch judgment threshold at the palm detection frequency, which is higher than the detection frequency, will be greater than the certain number. In such cases, the determination function 224 determines that the touch on the touch panel 100 was made by the palm and stops the touch coordinate output.

[0053] On the other hand, if the number of cross points is below 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 this, the processes from step S1 to step S8 are repeatedly executed at regular intervals.

[0054] In step S42, the determination function 224 may compare the number of sensor electrode crossing points above the touch detection threshold in the volume value measured at the detection frequency with the number of sensor electrode crossing points above the touch detection threshold in the volume value measured at the palm detection frequency, and proceed to either step S6 or S7 based on this comparison result. Since the palm detection frequency is a higher frequency than the detection frequency, in the case of a finger touch, if the crossing points of sensor electrodes whose volume changes due to the attached liquid are spread out, the number of sensor electrode crossing points above the touch detection threshold will be less when measured at the palm detection frequency than when measured at the detection frequency. On the other hand, in the case of a palm touch, the number of sensor electrode crossing points above the touch detection threshold is the same whether measured at the palm detection frequency or the detection frequency. For this reason, if the number of sensor electrode crossing points above the touch detection threshold when measured at the palm detection frequency is a certain number or more less than the number of sensor electrode crossing points above the touch detection threshold when measured at the detection frequency, it is determined that the touch is made by a finger. On the other hand, if the number of sensor electrode crossover points above the touch detection threshold measured at the palm detection frequency is approximately the same as the number of sensor electrode crossover points above the touch detection threshold measured at the detection frequency, then it is determined that the touch is caused by a palm.

[0055] Thus, according to Embodiment 4, it is possible to distinguish between the palm and the finger even when liquid is present, thereby improving operability.

[0056] Embodiment 5. Figure 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 Figure 10 comprises 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 from 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 the machine tool.

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

[0058] The configurations shown in the embodiments described above are merely examples of the content of this disclosure, and can be combined with other known technologies, combined with other embodiments, and some parts of the configuration can be omitted or modified without departing from the gist of this disclosure.

[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 device comprising: a touch panel having a touch sensor having a capacitive sensor electrode; and a controller for controlling the touch panel, wherein the controller includes: a detection unit for detecting the adhesion of liquid to the touch panel when a user makes contact with a first position on the touch panel; a calculation unit for calculating the conductivity of the adhered liquid based on the capacitance measurement results at a plurality of first detection frequencies when the detection unit detects the adhesion of liquid; a determination unit for determining a second detection frequency for deriving the first position that was touched on the touch panel based on the calculated conductivity; and a derivation unit for deriving the first position that was touched by the user using the determined second detection frequency.

2. The touch panel device according to claim 1, further comprising an output unit that outputs the first position derived by the derivation unit to an external device.

3. The touch panel device according to claim 1 or 2, characterized in that the calculation unit calculates the conductivity of the adhering liquid using the difference in capacitance values ​​at the same touch sensor position measured at multiple first detection frequencies.

4. The touch panel device according to claim 1 or 2, characterized in that the calculation unit determines the relationship between the half-width of the touch point (which is the peak) 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 first detection frequencies and the change in capacitance, and calculates the conductivity of the adhering liquid based on the relationship.

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

6. The touch panel device according to claim 5, characterized in that, if the calculated conductivity is equal to or greater than the first threshold, the determination unit increases the touch detection threshold, which is a threshold for determining whether a finger has touched the panel based on a change in capacitance, compared to before the liquid was applied.

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

8. The touch panel device according to claim 5, characterized in that the determination unit determines the second detection frequency based on the calculated conductivity if the calculated conductivity is equal to or greater than the first threshold; if the calculated conductivity is less than the first threshold but equal to or greater than the second threshold which is smaller than the first threshold, it reduces the number of touch points, which is the number of locations on the touch panel that can be touched and operated simultaneously, from the number before the liquid was applied and determines the second detection frequency based on the calculated conductivity; and if the calculated conductivity is less than the second threshold but equal to or greater than the third threshold which is smaller than the second threshold, it increases the touch determination threshold, which is the threshold for determining whether a finger has touched the panel based on a change in capacitance, from the number before the liquid was applied and determines the second detection frequency based on the calculated conductivity.

9. The touch panel device according to any one of claims 1 to 5, wherein the controller further comprises a measuring unit that, when measuring capacitance, measures the amount of variation of the capacitance measurement value with respect to time, and changes the first detection frequency to another frequency when the amount of variation is greater than a certain value.

10. The touch panel device according to any one of claims 1 to 5, characterized in that the determination unit determines that a hand touch has occurred if the number of crossing points of the sensor electrodes where the capacitance change measured at a detection frequency for determining hand touch that is higher than a plurality of first detection frequencies is greater than or equal to a touch determination threshold, which is a threshold for determining that a finger has touched the sensor due to the change in capacitance, is greater than a certain number.

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

Images