JP7221501B1 - Coordinate calculation device, touch panel, and coordinate calculation method - Google Patents

Abstract

An object of the present invention is to appropriately calculate coordinates even when water adheres to a mutual capacitance method. A coordinate calculation device (20) includes a first sum calculation section (611) that calculates the sum of variations in capacitance, a first coordinate calculation section (621) that calculates a first coordinate, and a transmission A switching unit (71) for switching between the electrode (14) and the receiving electrode (12), a second summation calculating unit (612) for calculating the sum of capacitance changes after switching, and a second coordinate for calculating A second coordinate calculator (622) and a two-dimensional coordinate calculator (623) that calculates two-dimensional coordinates from the first coordinates and the second coordinates. [Selection drawing] Fig. 36

Description

Application of Article 30, Paragraph 2 of the Patent Law ・Place of publication Mitsubishi Electric Corporation Nagoya Works meeting room Date of publication September 30, 2020 ・Place of publication Mitsubishi Electric Corporation Nagoya Works meeting room Date of publication January 2021 Month 6 January 19, 2021 January 29, 2021 March 2, 2021 March 3, 2021 March 11, 2021 ・Place of sale Ryosan Co., Ltd. Nagoya Daiichi Branch Sales date January 21, 2021 ・Published location Mikasa Shoji Co., Ltd. Conference room Published date February 2, 2021 ・Published location System Gear Co., Ltd. Conference room Published date 2021 March 17 ・Place of disclosure Technate Co., Ltd. Conference room Date of disclosure March 31, 2021 ・Location of disclosure Mitsubishi Electric Corporation, Nagoya Works Date of disclosure March 31, 2021 ・Location of disclosure Technate Co., Ltd. Meeting room Release date: June 18, 2021 ・Place of release: EJENTS Date of release: June 25, 2021 ・Place of release: System Gear Co., Ltd. Meeting room Release date: March, 2021 27th ・Place of sale Sanwa Technos Co., Ltd. Kyoto Branch Sales Section 2 Date of sale May 18, 2021 ・Place of publication Sanwa Technos Co., Ltd. Conference room Date of release July 12, 2021 8th of Reiwa 18th of the month

The present invention relates to a coordinate calculation device, a touch panel, and a coordinate calculation method for calculating coordinates indicating a position touched by a user.

2. Description of the Related Art In recent years, electronic devices such as mobile terminals and PDAs have become mainstream devices that use a touch panel as input means for user operation. A touch panel is, for example, an input device that outputs a signal according to a touch position when a user's finger touches it.

By the way, the touch panel erroneously detects the water droplet as the user's touch position when the capacitance changes due to water droplets adhering to the touch panel.

False detection of the user's touch position on the touch panel sometimes causes serious problems. For example, programmable displays equipped with touch panels have been developed in the field of FA (factory automation) and are generally installed in environments such as factory facilities. In such an environment, erroneous detection of the user's touch position by the touch panel may lead to a serious accident. Therefore, it is important to take measures to prevent erroneous detection of the user's touch position by the touch panel.

In consideration of such problems, Patent Document 1 discloses a technique for determining whether or not a contact with a mutual capacitance touch panel is a water drop.

Also disclosed is a technique for stopping coordinate output when water is detected. In this case, coordinate output resumes when water is no longer detected. In particular, in the mutual capacitance method, it is difficult to prevent erroneous coordinate output when a water-adhered area is touched. Therefore, in the mutual capacitance method, coordinate output is not performed in a water-adhering area while water is attached, and coordinate output is resumed when water is no longer detected. As a result, erroneous coordinate output due to adhesion of water can be prevented.

Also, the self-capacitance method is less susceptible to water than the mutual capacitance method. Therefore, when water is detected, there is also a technique of switching from the mutual capacitance method to the self-capacitance method to calculate the coordinates and output the coordinates.

Patent No. 4994489 (registered on May 18, 2012) Japanese Patent Application Laid-Open No. 2015-191550 (published on November 2, 2015)

As described above, if the coordinate output is not performed when water is attached, the coordinate output cannot be performed until the water disappears. Even if the coordinate output is not performed only for the water-attached area, the coordinate output cannot be performed for that area until the water is removed.

In addition, when switching from the mutual capacitance method to the self-capacitance method according to the adhesion of water, it is necessary to provide functions corresponding to the two methods, the mutual capacitance method and the self-capacitance method, which complicates the circuits and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to realize a coordinate calculating apparatus or the like that can appropriately calculate coordinates even if water adheres to the mutual capacitance method.

To solve the above problems, a coordinate calculation device according to an aspect of the present invention is a coordinate calculation device that calculates coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method, and includes: a first summation calculation unit that calculates the sum of capacitance variations between the reception electrode and each transmission electrode; and from the result calculated by the first summation calculation unit, the transmission electrode is connected a first coordinate calculation unit that calculates a first coordinate indicating a touch position in a direction of the transmission electrode, which is the direction in which the touch panel is located; a switching unit that switches between the transmission electrode and the reception electrode; and a reception electrode after switching by the switching unit. A second total sum calculation for calculating a sum of changes in capacitance between the switched receiving electrode and each switched transmitting electrode, which is the transmitting electrode after switching by the switching unit, along the switching receiving electrode. and a second coordinate calculation unit that calculates second coordinates indicating a touch position in a direction of the post-switching transmission electrodes, which is the direction in which the post-switching transmission electrodes are connected, from the result calculated by the second summation calculation unit. and a two-dimensional coordinate calculator that calculates two-dimensional coordinates of a touch position on the touch panel from the first coordinates and the second coordinates.

According to the above configuration, the first coordinate is calculated from the sum of the amount of change in capacitance between the receiving electrode and each transmitting electrode. Then, the receiving electrode and the transmitting electrode at the time of calculating the first coordinate are switched, and the second coordinate is calculated based on the total amount of change in capacitance between the receiving electrode and each transmitting electrode. Then, the two-dimensional coordinates are calculated using the first coordinates and the second coordinates. As a result, the coordinates can be calculated while canceling out the influence of adhering water, so even if water is adhering, the coordinates indicating the touch position can be calculated accurately.

To solve the above problems, a coordinate calculation device according to an aspect of the present invention is a coordinate calculation device that calculates coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method, and includes: a first difference calculation unit for calculating the sum of differences between adjacent reception electrodes in the amount of change in capacitance between the reception electrode and each transmission electrode; and the result calculated by the first difference calculation unit. a third total sum calculating unit for calculating the sum of capacitance variations between the receiving electrode and each transmitting electrode along the receiving electrode, and from the result calculated by the third sum calculating unit, a first coordinate calculation unit that calculates a first coordinate indicating a touch position in a transmission electrode direction that is a direction in which the transmission electrode is connected; a switching unit that switches between the transmission electrode and the reception electrode; and switching by the switching unit. Along the post-switching receiving electrode, which is the subsequent receiving electrode, the amount of change in capacitance between the post-switching receiving electrode and the post-switching transmitting electrode, which is the transmitting electrode after switching by the switching unit, is adjacent to each other. a second difference calculation unit that calculates the sum of differences between the post-switching reception electrodes, and from the result calculated by the second difference calculation unit, along the post-switching reception electrodes, the post-switching reception electrodes and each post-switching transmission A fourth total sum calculating unit that calculates the sum of the amount of change in capacitance between electrodes, and from the result calculated by the fourth total sum calculating unit, the direction in which the post-switching transmission electrode is connected is determined to be the direction after switching. a second coordinate calculator that calculates a second coordinate indicating a touch position in the transmission electrode direction; and a two-dimensional coordinate calculator that calculates a two-dimensional coordinate of the touch position on the touch panel from the first coordinate and the second coordinate. , is a configuration.

According to the above configuration, the first coordinate is determined based on the amount of change in capacitance calculated from the sum of the differences between the amounts of change in capacitance between the receiving electrode and each transmitting electrode and between adjacent receiving electrodes. calculate. Then, the receiving electrode and the transmitting electrode at the time of calculating the first coordinate are switched, and the second coordinate is the difference between the capacitance change amount between the receiving electrode and each transmitting electrode and between the adjacent receiving electrodes. It is calculated based on the amount of change in capacitance calculated from the total sum. Then, the two-dimensional coordinates are calculated using the first coordinates and the second coordinates. As a result, the coordinates can be calculated while canceling out the influence of adhering water, so even if water is adhering, the coordinates indicating the touch position can be calculated accurately.

A coordinate calculation device according to an aspect of the present invention includes a first average value calculation unit that calculates a first average value, which is an average value of the calculated values for each of the adjacent receiving electrodes, calculated by the first difference calculation unit. and a second average value calculating unit that calculates a second average value that is an average value of the calculated values for each of the adjacent receiving electrodes calculated by the second difference calculating unit, and the third total sum calculation The unit calculates the sum of the amount of change in the capacitance using the value obtained by subtracting the first average value from the result calculated by the first difference calculation unit, and the fourth sum calculation unit, The sum of the amounts of change in the capacitance may be calculated using a value obtained by subtracting the second average value from the result calculated by the second difference calculation unit.

According to the above configuration, the amount of change in capacitance is calculated by subtracting the average value of the difference, so even if the balance of the device that measures the difference is out of balance, the coordinates can be calculated accurately.

In the coordinate calculation device according to one aspect of the present invention, when the minimum value of the amount of change in capacitance calculated by the third summation calculation unit is negative, the value added by the negative value is added to the third summation calculation. If the minimum value of the amount of change in capacitance calculated by the fourth summation calculation unit is negative, the value added by the negative value is used as the calculation result of the fourth summation calculation unit. can be anything.

According to the above configuration, it is possible to accurately calculate the coordinates even when the amount of change in capacitance calculated from the difference is lower.

A touch panel according to an aspect of the present invention may have a configuration including the coordinate calculation device described above. Thereby, there can exist an effect mentioned above.

To solve the above-described problems, a coordinate calculation method according to an aspect of the present invention is a coordinate calculation method for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method, comprising: a first total sum calculating step of calculating the sum of capacitance variations between the receiving electrode and each transmitting electrode; a first coordinate calculation step of calculating a first coordinate indicating the touch position in the direction of the transmitting electrode, which is the direction in which the a second summation calculating step of calculating a sum of changes in capacitance along the receiving electrodes between the switching receiving electrodes and the switching transmitting electrodes, which are the transmitting electrodes after switching in the switching step; a second coordinate calculation step of calculating a second coordinate indicating a touch position in a direction of the post-switching transmission electrodes, which is a direction in which the post-switching transmission electrodes are connected, from the results calculated in the second summation calculation step; a two-dimensional coordinate calculation step of calculating two-dimensional coordinates of the touch position on the touch panel from the first coordinates and the second coordinates.

To solve the above-described problems, a coordinate calculation method according to an aspect of the present invention is a coordinate calculation method for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method, comprising: a first difference calculating step of calculating the sum of the differences between the adjacent receiving electrodes in the amount of change in capacitance between the receiving electrode and each transmitting electrode; and the result calculated in the first difference calculating step. From the result calculated in the third summation calculation step, the third summation calculation step of calculating the summation of the amount of change in capacitance between the reception electrode and each transmission electrode along the reception electrode, a first coordinate calculation step of calculating a first coordinate indicating a touch position in a transmission electrode direction that is a direction in which the transmission electrode is connected; a switching step of switching between the transmission electrode and the reception electrode; Along the post-switching receiving electrode, which is the receiving electrode after switching, the amount of change in capacitance between the post-switching receiving electrode and the post-switching transmitting electrode, which is the transmitting electrode after switching in the switching step. a second difference calculating step of calculating the sum of differences between adjacent receiving electrodes; A fourth total sum calculating step of calculating the sum of the amount of change in the capacitance between the electrodes, and from the results calculated in the fourth total sum calculating step, the direction in which the post-switching transmission electrode is connected is determined to be the post-switching direction. a second coordinate calculation step of calculating a second coordinate indicating a touch position in a transmission electrode direction; and a two-dimensional coordinate calculation step of calculating a two-dimensional coordinate of the touch position on the touch panel from the first coordinate and the second coordinate. ,including.

According to one aspect of the present invention, in the mutual capacitance method, coordinates indicating a touched position can be accurately calculated even if water adheres.

FIG. 4 is a diagram for explaining touch detection, and is a diagram showing the shape of a transmission electrode; FIG. FIG. 4 is a diagram for explaining touch detection, and is a diagram showing the shape of a receiving electrode; FIG. It is a figure which shows a mode that the transmission electrode and the reception electrode were piled up. FIG. 4 is a diagram showing a state when a pulse voltage is applied to a transmission electrode; It is a figure which shows a mode that the touch panel was touched with a finger. (a), (b) and (c) are diagrams showing current waveforms of receiving electrodes included in the touch panel when there is no adhesion of water on the touch panel and there is no touch. (a), (b), and (c) are diagrams showing voltage waveforms of receiving electrodes included in the touch panel when there is no adhesion of water on the touch panel and there is no touch. (a), (b) and (c) are diagrams showing voltage waveforms of the receiving electrodes when the touch panel is touched and water is not attached. (a), (b), and (c) are diagrams showing voltage waveforms of the receiving electrodes when water is attached to the touch panel and there is no touch. (a) and (b) are diagrams showing the correspondence relationship between the maximum value of the voltage waveform of the receiving electrode and the amount of change in capacitance of the receiving electrode. (a) and (b) are diagrams showing the amount of change in the capacitance when there is no adhesion of water on the touch panel and there is no touch. (a) and (b) are diagrams showing the amount of change in the capacitance when there is no water adhesion on the touch panel and there is a touch. (a) and (b) are diagrams showing the amount of change in the capacitance when water adheres to the touch panel and there is no touch. (a) and (b) are diagrams showing occurrence of a ghost due to a finger on the touch panel. (a) and (b) are diagrams showing occurrence of a ghost due to a finger on the touch panel. FIG. 4 is a diagram showing the arrangement of ghosts generated by a finger on the touch panel; (a) and (b) are diagrams showing the amount of change in the capacitance when water obliquely adheres to the touch panel. (a) and (b) are diagrams showing the amount of change in the capacitance when water obliquely adheres to the touch panel. It is a figure which shows arrangement|positioning of the said variation|change_quantity of the said electrostatic capacity when water adheres on the said touch panel diagonally. It is a figure which shows a mode that the round water adhered on the said touch panel. It is a figure which shows arrangement|positioning of the said capacitance change amount when the round water adheres on the said touch panel. It is a figure which shows arrangement|positioning of the said capacitance change amount when the round water adheres on the said touch panel. It is a figure which shows a mode that three water connected and adhered on the said touch panel. FIG. 10 is a diagram showing the arrangement of capacitance variations caused by three pieces of water adhering to the touch panel and connected to each other; It is a figure which shows a mode that the round water adhered on the said touch panel. It is a figure which shows a mode that three water connected and adhered on the said touch panel. FIG. 10 is a diagram showing the arrangement of capacitance variations caused by three pieces of water adhering to the touch panel and connected to each other; It is a figure which shows a mode that the round water adhered on the said touch panel. It is a figure which shows a mode that four water connected and adhered on the said touch panel. FIG. 10 is a diagram showing the arrangement of capacitance variations caused by four pieces of water adhering to the touch panel and connected to each other; FIG. 10 is a diagram showing the arrangement of capacitance variation values caused by four pieces of water adhering to the touch panel and connected to each other; 1 is a block diagram showing a schematic configuration of a touch panel device; FIG. 4 is a flow chart showing a processing procedure of a method for determining the presence or absence of water adhesion. FIG. 10 is a diagram showing the amount of change in the capacitance of the receiving electrode included in the touch panel and the measured value thereof when there is no water adhesion and there is a touch on the touch panel according to the modification; 10 is a flow chart showing a processing procedure of a method for determining presence/absence of water adhesion according to a modification; 1 is a functional block diagram showing the main configuration of a coordinate calculation device according to an embodiment of the present invention; FIG. FIG. 10 is a diagram for explaining the sum of variations in capacitance; FIG. 10 is a diagram for explaining the sum total of changes in capacitance after switching between a transmitting electrode and a receiving electrode; It is a figure which shows the amount of change of an electrostatic capacitance when water adheres and the said area|region is touched with a finger. It is a flowchart which shows the flow of a process in a coordinate calculation apparatus. It is a functional block diagram which shows the principal part structure of the coordinate calculation apparatus which concerns on another embodiment of this invention. (a) and (b) are diagrams showing measured values and amounts of change in capacitance when the differential amplifier is out of balance. (a), (b) and (c) are diagrams showing a measured value, a measured value (corrected), and an amount of change in capacitance when the measured value is corrected using an average value. (a), (b), and (c) are diagrams showing the amount of change in capacitance when the amount of change in capacitance is downward. It is a flowchart which shows the flow of a process in a coordinate calculation apparatus.

[Mechanism for detecting touches]
First, as a premise of the embodiments of the present invention, a mechanism for calculating coordinates indicating a touched position on a touch panel that performs touch detection by a mutual capacitance method will be described. Touch detection by the mutual capacitance method measures the capacitance between the transmission electrode 14 and the reception electrode 12, and detects that there has been a touch when the measured capacitance is smaller than the normal state. The capacitance between the transmitting electrode 14 and the receiving electrode 12 is measured by applying a square-wave pulse-shaped voltage to the transmitting electrode 14 and measuring the potential generated in the receiving electrode 12 by electrostatic induction.

The structure of a mutual capacitance type capacitive touch panel will be described with reference to FIGS. Here, an electrode structure called a diamond pattern will be described as an example. Each electrode is made by molding an ITO film.

FIG. 1 shows the shape of the transmission electrodes 14 (T1 to T5). FIG. 1 shows an example in which the transmitting electrodes 14 are connected in a horizontal row in a square pattern.

FIG. 2 shows the shape of the receiving electrodes 12 (R1 to R5). FIG. 2 shows an example in which the receiving electrodes 12 are connected in a vertical line in a square pattern.

FIG. 3 shows how the transmitting electrode 14 and the receiving electrode 12 are superimposed. Here, the transmitter electrodes 14 are shown in gray for ease of identification. The transmitting electrode 14 and the receiving electrode 12 are insulated by an insulating layer.

Next, with reference to FIGS. 4 and 5, the principle of touch detection will be described. FIG. 4 shows a state when a pulse voltage is applied to the transmission electrode 14. As shown in FIG. As shown in FIG. 4, the transmitting electrodes 14 and the receiving electrodes 12 are arranged on the substrate 15 of the touch panel 1 so as to overlap with each other with an insulating layer interposed therebetween. When a square-wave pulse driving voltage is applied to one of the transmitting electrodes 14, the receiving electrode 12 adjacent to the transmitting electrode 14 will receive a A current flows through the capacitive coupling that is formed. As a result, charges are induced in the receiving electrode 12 and the potential changes. In addition, since the electrode surface of the transmitting electrode 14 faces a wide space, electric lines of force that do not contribute to coupling with the receiving electrode 12 are radiated into space. All transmission electrodes 14 to which no drive voltage is applied are connected to a fixed potential. As a result, all the transmission electrodes 14 to which no drive voltage is applied are grounded.

Note that there are cases where a drive voltage is applied to a plurality of adjacent transmission electrodes 14 for reasons such as increasing the sensitivity of touch detection. Since the same principle is established by regarding these plurality of transmission electrodes 14 as one transmission electrode 14, a configuration in which a drive voltage is applied to one transmission electrode 14 will be described in this embodiment.

FIG. 5 shows how a finger F touches the touch panel 1 . When the finger F touches the touch panel 1, the finger F absorbs the lines of electric force flowing to the receiving electrode. This reduces the change in the potential of the receiving electrode 12 . By detecting the amount by which the change in potential has decreased, the decrease in the capacitance (mutual capacitance) between the transmitting electrode 14 and the receiving electrode 12 can be measured.

[Method for detecting water adhesion]
With reference to FIG. 6, the current waveform between the receiving electrode 12 and the transmitting electrode 14 when the mutual capacitance type touch panel 1 is not touched and water is not attached will be described. FIG. 6(a) is a schematic cross-sectional view of the touch panel 1, FIG. 6(b) is a diagram showing an applied voltage applied to the transmitting electrode 14, and FIG. 6(c) is a receiving electrode 12 and a transmitting electrode. 14 shows the current waveform between 14. FIG.

As shown in (a) of FIG. 6 , the touch panel 1 includes a front cover 11 , receiving electrodes 12 , an insulating layer 13 , transmitting electrodes 14 and a substrate 15 . The substrate 15 is a substrate made of an insulating material, and the transmitting electrodes 14, the insulating layer 13, the receiving electrodes 12, and the front cover 11 are laminated in this order on the substrate 15. As shown in FIG. Note that the touch panel 1 is a known mutual capacitance type touch panel, and a description of its structure is omitted here.

When there is no water on the touch panel 1 and there is no touch, a capacitance C1 is formed between the reception electrodes 12 and the transmission electrodes 14 via the front cover 11 and the insulating layer 13 . When the voltage shown in FIG. 6(b) is applied to the transmitting electrode 14, the current waveform between the receiving electrode 12 and the transmitting electrode 14 becomes the current waveform shown in FIG. 6(c).

Next, with reference to FIG. 7, voltage waveforms between the receiving electrodes 12 and the transmitting electrodes 14 when the mutual capacitance touch panel 1 is not touched and water is not attached will be described. FIG. 7(a) is a schematic cross-sectional view of the touch panel 1, FIG. 7(b) is a diagram showing applied voltages applied to the transmitting electrodes 14, and FIG. 14 is a diagram showing voltage waveforms between .

As shown in (a) of FIG. 7 , the touch panel 1 includes a front cover 11 , receiving electrodes 12 , an insulating layer 13 , transmitting electrodes 14 and a substrate 15 . The substrate 15 is a substrate made of an insulating material, and the transmitting electrodes 14, the insulating layer 13, the receiving electrodes 12, and the front cover 11 are laminated in this order on the substrate 15. As shown in FIG. Note that the touch panel 1 is a known mutual capacitance type touch panel, and a description of its structure is omitted here.

When there is no water on the touch panel 1 and there is no touch, a capacitance C1 is formed between the reception electrodes 12 and the transmission electrodes 14 via the front cover 11 and the insulating layer 13 . When the voltage shown in FIG. 7(b) is applied to the transmitting electrode 14, the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 becomes the voltage waveform shown in FIG. 7(c).

Next, with reference to FIG. 8, voltage waveforms between the receiving electrodes 12 and the transmitting electrodes 14 when there is no water on the touch panel 1 and there is a finger F touch will be described. FIG. 8(a) is a schematic cross-sectional view of the touch panel 1, FIG. 8(b) is a diagram showing an applied voltage applied to the transmitting electrode 14, and FIG. 14 is a diagram showing voltage waveforms between .

When there is no water on the touch panel 1 and there is a touch, as in FIG. A capacitance C1 is formed.

Furthermore, the touch of the finger F forms capacitances C2, C3 and C4, respectively.

Since the human body has a larger surface area than the receiving electrodes 12, the capacitance C4 is larger than the capacitances C1, C2 and C3 and the capacitances C1, C2 and C3 are comparable. Also, the human body may have conductivity with the ground potential.

Since the capacitance C3 and the human body are connected in series by the touch of the finger F, when the voltage shown in FIG. The current is largely shunted. Therefore, the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 is smaller than the maximum value of the voltage waveform shown in (c) of FIG. (b) of FIG. 8 shows the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 .

Finally, with reference to FIG. 9, voltage waveforms between the receiving electrode 12 and the transmitting electrode 14 when the touch panel 1 is adhered with water W and not touched will be described. FIG. 9(a) is a schematic cross-sectional view of the touch panel 1, FIG. 9(b) is a diagram showing an applied voltage applied to the transmitting electrode 14, and FIG. 9(c) is a receiving electrode 12 and a transmitting electrode. 14 is a diagram showing voltage waveforms between .

When water W adheres to the touch panel 1 and there is no touch, static electricity is applied between the receiving electrode 12 and the transmitting electrode 14 via the front cover 11 and the insulating layer 13, as in (a) of FIG. A capacitance C1 is formed. Furthermore, the adhesion of water W forms capacitances C5 and C6, respectively.

Here, unlike when the finger F shown in FIG. 8A touches the touch panel 1, the water W is not electrically connected to the ground potential. Therefore, the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 is larger than the maximum value of the voltage waveform shown in FIG. 7(c). (b) of FIG. 9 shows the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 .

FIG. 10(a) shows the magnitude of the maximum voltage waveform between the receiving electrode 12 and the transmitting electrode 14, and FIG. 10(b) shows the static voltage between the receiving electrode 12 and the transmitting electrode 14. It is a figure which shows the variation|change_quantity of an electric capacity.

As described with reference to FIGS. 7 to 9, the maximum value of the voltage waveform of the receiving electrode 12 is proportional to the capacitance between the receiving electrode 12 and the transmitting electrode 14. FIG. The inventors paid attention to the amount of change in the capacitance between the receiving electrode 12 and the transmitting electrode 14 that occurs when the state changes from a finger touch and no water adhesion state to a certain state.

As shown in (a) and (b) of FIG. 10, the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 when there is no finger touch and no water adhesion is used as a reference. , the amount of change in capacitance between the receiving electrode 12 and the transmitting electrode 14, which decreases due to finger touch, is detected as a positive value. On the other hand, the amount of change in capacitance between the receiving electrode 12 and the transmitting electrode 14, which increases due to adhesion of water, is detected as a negative value.

11A and 11B show the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 and the , and the amount of change in capacitance between the transmission electrode 14. FIG.

In FIG. 11(a), T1 denotes the transmission electrode 14 to which voltage is applied, and T2 denotes the transmission electrode 14 to which no voltage is applied. As shown in FIG. 11(b), the capacitance between the receiving electrode 12 and the transmitting electrode 14 is equal to any of the receiving electrodes 12 (R1 to R12 in the figure represent the receiving electrodes 12). , no change in capacitance is observed.

12A and 12B show the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 and the , and the amount of change in capacitance between the transmission electrode 14. FIG.

In FIG. 12(a), F1 represents the range touched by the finger. As shown in (b) of FIG. 12, the amount of change in capacitance between the receiving electrodes 12 (here, R3 and R4) and the transmitting electrode 14 (here, T1) is positive due to finger touch. Detected as a value.

If the length of each side of the range where the touched finger touches the touch panel 1 is about 1 cm, the spacing between the receiving electrodes 12 and the spacing between the transmitting electrodes 14 are each the length of each side of the finger contact range. It is about 1/2 of the length, which is about 5 mm. In FIG. 12, the finger is touching the top of the receiving electrodes 12 (R3 and R4). In FIG. 12, it is assumed that only the upper portion of the transmission electrode 14 (T1) is touched in order to explain the detection principle.

13A and 13B show the maximum value of the voltage waveform between the receiving electrode 12 and the transmitting electrode 14 and the , and the amount of change in capacitance between the transmission electrode 14. FIG.

In FIG. 13(a), W1 represents the area where water adheres. As shown in (b) of FIG. 13, due to water adhesion, the amount of change in capacitance between the receiving electrode 12 (here, R3 and R4) and the transmitting electrode 14 (here, T1) becomes negative. Detected as a value.

If the length of each side of the range where water adheres to the touch panel 1 is about 1 cm, the spacing between the receiving electrodes 12 and the spacing between the transmitting electrodes 14 are the same as the length of each side of the range where water adheres. It is about 1/2 of the length, which is about 5 mm. In FIG. 13, water adheres to the top of the receiving electrodes 12 (R3 and R4). In addition, in FIG. 13, in order to explain the detection principle, it is assumed that water adheres only to the upper part of the transmission electrode 14 (T1).

As can be seen by comparing (b) of FIG. 12 and (b) of FIG. It is smaller when there is water adhering to the touch panel 1 and there is no touch than when there is no touch and there is no touch.

The inventors of the present invention have discovered the problem of the above-described detection principle, and as a result of further intensive studies, have invented a technique for solving the above-described problem of the detection principle. First, the problems found by the inventors will be described.

14A and 14B are diagrams for explaining the principle of occurrence of a ghost at corner positions with these two points as vertices when the touch panel 1 is touched obliquely with two fingers. Note that the ghost means the amount of change in capacitance that occurs at a position not touched with a finger and at a position where water is not adhered.

The finger F2 is strongly electrostatically coupled with the transmission electrode T2 to which no voltage is applied while the voltage is applied to the transmission electrode T1. A current flows between the finger F1 and the finger F2 through the human body (hand), so that the receiving electrode R6 is formed between each of the receiving electrodes R6 and R7 to which the finger F2 is electrostatically coupled and the transmitting electrode T1. , and R7 and the transmission electrode T1, a voltage waveform similar to that when water adheres to the intersection of the transmission electrode T1 is generated. However, the current flowing through the human body (hand) between the fingers F1 and F2 is smaller than the current flowing out of the human body through the human body. Therefore, the voltage waveform generated by the current flowing between the fingers F1 and F2 is smaller than when water is attached.

As a result, as shown in FIG. 14(b), the amount of change in each capacitance between each of the receiving electrodes R6 and R7 and the transmitting electrode T1 is detected as a negative value.

On the other hand, as shown in FIGS. 15A and 15B, the finger F1 is strongly electrostatically coupled with the transmission electrode T1 to which no voltage is applied while the voltage is applied to the transmission electrode T2. A current flows between the finger F1 and the finger F2 through the human body (hand), so that the receiving electrode R3 is formed between each of the receiving electrodes R3 and R4 to which the finger F1 is electrostatically coupled and the transmitting electrode T2. , and R4 and the transmission electrode T2, a voltage waveform similar to that in the case where water adheres to the intersection of the transmission electrode T2 is generated. However, the current flowing through the human body (hand) between the fingers F1 and F2 is smaller than the current flowing out of the human body through the human body. Therefore, the voltage waveform generated by the current flowing between the fingers F1 and F2 is smaller than when water is attached.

As a result, as shown in FIG. 15(b), the amount of change in capacitance between each of the receiving electrodes R3 and R4 and the transmitting electrode T2 is detected as a negative value.

16A and 16B are schematic diagrams for explaining ghosts generated based on the principle of ghost generation shown in FIGS. 14 and 15 described above. In FIG. 16, when a voltage is applied to the transmitting electrode T1 or T2, the amount of change in capacitance between each of the receiving electrodes R3, R4, R6, and R7 and the transmitting electrode T1, and the amount of change in the capacitance between the receiving electrodes R3, R4, The amount of change in capacitance between each of R6 and R7 and the transmission electrode T2 is schematically shown on the touch panel 1. FIG.

As shown in FIG. 16, when the touch panel 1 is touched obliquely with two fingers, a ghost occurs at the other diagonal position of a rectangle with these two points as vertices. become.

FIGS. 17(a) and 17(b) are diagrams for explaining the principle of occurrence of a ghost at corner positions with these two points as apexes when two pieces of water adhere to the touch panel 1 at an angle. As shown in FIG. 17(b), the water W1 and the water W2 are electrically connected by a conductor, and an electric current flows between the water W1 and the water W2 via the conductor. In addition, to be electrically connected by a conducting wire specifically assumes a situation in which two pieces of water are connected by thin lines of water.

When a voltage is applied to the transmitting electrode T1, if there is no electrical connection between the water W1 and the water W2, the adhesion of the water W1 will cause the contact between each of the receiving electrodes R3 and R4 and the transmitting electrode T1. Each capacitance change should be detected as a negative value.

However, in FIGS. 17(a) and 17(b), water W1 and water W2 are electrically connected to each other by a conducting wire. The amount of change in each capacitance between each and the transmitting electrode T1 will turn from a negative value to a positive value.

As a result, the amount of change in capacitance between each of the receiving electrodes R3 and R4 and the transmitting electrode T1 is detected as a positive value.

It should be noted that, due to the current flowing between the water W1 and the water W2 through the conducting wire, the water W2 is electrostatically coupled between the receiving electrodes R6 and R7 and the transmitting electrode T1. A voltage waveform similar to that when water adheres to the intersection of each of R7 and the transmission electrode T1 is produced. As a result, the amount of change in each capacitance between each of the receiving electrodes R6 and R7 and the transmitting electrode T1 is detected as a negative value.

On the other hand, as shown in FIGS. 18(a) and 18(b), when a voltage is applied to the transmission electrode T2, if the water W1 and the water W2 are not electrically connected, the water W2 adheres. is detected as a negative value.

However, in FIGS. 18(a) and 18(b), the water W1 and the water W2 are electrically connected by a conducting wire, so that current flows between them, causing the receiving electrodes R6 and R7 to The amount of change in each capacitance between each and the transmitting electrode T2 will turn from a negative value to a positive value.

As a result, the amount of change in each capacitance between each of the receiving electrodes R6 and R7 and the transmitting electrode T2 is detected as a positive value.

It should be noted that, due to the current flowing between the water W1 and the water W2 through the conducting wire, the water W1 is electrostatically coupled between the receiving electrodes R3 and R4 and the transmitting electrode T2. A voltage waveform similar to the case where water adheres to the intersection of each of R4 and the transmitting electrode T2 is produced. As a result, the amount of change in each capacitance between each of the receiving electrodes R3 and R4 and the transmitting electrode T2 is detected as a negative value.

19A and 19B are schematic diagrams for explaining ghosts generated based on the principle of ghost generation shown in FIGS. 17 and 18 described above. In FIG. 19, when a voltage is applied to the transmitting electrode T1 or T2, the amount of change in capacitance between each of the receiving electrodes R3, R4, R6, and R7 and the transmitting electrode T1, and the amount of change in the capacitance between the receiving electrodes R3, R4, The amount of change in capacitance between each of R6 and R7 and the transmission electrode T2 is schematically shown on the touch panel 1. FIG.

As shown in FIG. 19, when two pieces of electrically connected water are obliquely attached to the touch panel 1, when one diagonal of a rectangle with these two points as vertices is defined as one diagonal, the other diagonal is positioned ghost will occur in

As can be seen from a comparison of FIGS. 16 and 19, the polarities (positive and negative) of the capacitance change amount are the same when two fingers are touched and when two pieces of water are attached. is.

Next, when round water adheres to the touch panel 1, the result is a combination of the above-mentioned two amounts of change in capacitance due to the adhesion of water. FIG. 20 is a schematic diagram showing how a round piece of water W3 adheres to the touch panel 1, and FIG. 21 is for explaining the amount of capacitance change between the reception electrode 12 and the transmission electrode 14 due to the adhesion of the water W3. It is a schematic diagram of. In FIG. 21, voltages are applied in the order of transmission electrode T1→transmission electrode T2→transmission electrode T3.

As shown in FIG. 21, the amount of change in capacitance due to water adhesion (the amount of change from a negative value to a positive value) and the amount of change in capacitance due to the generation of the above-mentioned ghost ( Amount of change in negative value) appears.

Inside the water W3, an amount of change in capacitance (amount of change in a negative value) due to water adhesion appears. Furthermore, the amount of change in capacitance (the amount of change in the negative value) due to the occurrence of the ghost appears inside the water W3. For this reason, the amount of change of these two negative values is superimposed and appears inside the water W3.

The problem of the above-described detection principle discovered by the present inventors can be summarized as follows.

(1) Erroneous Detection Due to Noise As described with reference to FIG. 13, the amount of change in capacitance due to adhesion of water is small. If the amount of change of the same level as the amount of change in capacitance shown in FIG. 13B is caused by noise, erroneous detection of water adhesion will occur.

(2) Erroneous detection due to multi-touch As described with reference to FIG. appear. For this reason, if the detection sensitivity is increased, the amount of change in capacitance due to the occurrence of a ghost will increase, and as a result, erroneous detection of water adhesion will occur.

(3) False detection that water adhesion is detected as a finger touch As explained using FIG. is detected. As a result, the finger touch is erroneously detected. In particular, when the detection sensitivity is increased, erroneous detection becomes significant.

A technique for solving the above-described problems invented by the present inventors will be described below with reference to FIGS. 22 to 31. FIG. Here, the case where water W3 adheres to the touch panel 1 shown in FIG. 21 will be described as an example.

As shown in FIG. 22, first, attention is paid to the upper left portion (the portion surrounded by the dotted line). Then, as shown in FIG. 23, this portion is considered to be formed by connecting water W11, water W12, and water W13.

FIG. 24 is a schematic diagram for explaining the amount of change in capacitance between the receiving electrode 12 and the transmitting electrode 14 due to the adhesion of water W11, water W12, and water W13. As shown in FIG. 24, capacitance change amounts 1 and 3 (negative to positive values) due to the respective adhesion of water W11 and water W13, water W11 and water W13 obliquely adhere. The amount of change in capacitance 5 (negative value) due to the ghost generated by this, and the amount of change in capacitance (negative value) due to the adhesion of water W12 and water W11 and water W13 adhered obliquely. A variation 2 (negative value) appears, which is the sum of the capacitance variation (negative value) due to the ghost generated thereby.

Next, as shown in FIG. 25, focus on the lower left portion (the portion surrounded by the dotted line). Then, as shown in FIG. 26, consider that this portion is formed by connecting water W13, water W12, and water W14.

FIG. 27 is a schematic diagram for explaining the amount of change in capacitance between the receiving electrode 12 and the transmitting electrode 14 due to the adhesion of water W13, water W12, and water W14. As shown in FIG. 27, capacitance changes 6 and 4 (changed from negative to positive) due to water W13 and water W14 adhering, water W13 and water W14 obliquely adhering. The amount of change in capacitance 8 (negative value) due to the ghost generated as a result, the amount of change in capacitance (negative value) due to the adhesion of water W12, and water W13 and water W14 obliquely adhere to each other. A change amount 7 (negative value) appears, which is the sum of the change amount (negative value) of the capacitance due to the ghost generated by the incident.

Next, as shown in FIG. 28, attention is paid to the left half of the water W3 shown in FIG. 21 (the portion enclosed by the dotted line). Then, as shown in FIG. 29, this portion is considered to be formed by connecting water W11, water W12, water W13 and water W14.

FIG. 30 is a schematic diagram for explaining the amount of capacitance change between the receiving electrode 12 and the transmitting electrode 14 due to the adhesion of water W11, water W12, water W13, and water W14. As shown in FIG. 30, the amount of change appears in which the amount of change in capacitance in the upper left portion shown in FIG. 24 and the amount of change in capacitance in the lower left portion shown in FIG. 27 are superimposed. The same can be said for the right half of the water W3 shown in FIG.

Here, when the number of transmitting electrodes 14 included in the adhering water increases, the amount of change in the capacitance of the outer periphery and inside of the water is added by the amount corresponding to the increase in the number of the transmitting electrodes 14 included. increasing.

However, when observing the increase in the amount of change in capacitance along each receiving electrode 12, it can be seen that the positive value increases and the negative value also increases at the same time.

Therefore, when the sum of the values of the amount of change in the capacitance obtained by the measurement on the receiving electrode 12 is calculated for each receiving electrode 12, the total value is calculated as follows: Even if it increases, the positive value and the negative value cancel each other out, so the positive value does not become large.

FIG. 31 shows the results of addition of overlapping portions, where +1 is the amount of change in one positive capacitance and -1 is the amount of change in one minus capacitance.

Summing along the receiving electrode R3, the total capacitance change is:
(-1) + (+2) + (-1) = 0
Summing along the receiving electrode R4, the total capacitance change is:
(+1) + (-3) + (+1) = -1
becomes.

When there is no water adhesion and there is a finger touch, as shown in FIG. 12, the amount of change in capacitance indicating a positive value becomes a large value on the positive side. Further, as shown in FIGS. 14 and 15, the amount of change in capacitance indicating a negative value due to a ghost generated by touching with a plurality of fingers has a smaller absolute value than the larger value on the positive side. Become.

Therefore, when there is a finger touch, the total amount of change in capacitance along the receiving electrode 12 becomes a large positive value.

Also, when there is a finger touch within the water-adhering range, the total amount of change in capacitance along the receiving electrode 12 directly under the finger becomes a large value on the positive side. However, the total amount of change in capacitance along the surrounding receiving electrodes 12 is not a large positive value, indicating that the finger is surrounded by water.

Therefore, if there is a finger touch in the area where water is attached, the calculation accuracy of the finger touch position will be low. is preferred. This can prevent outputting wrong coordinates.

(Configuration of touch panel device)
Next, the configuration of the touch panel device according to this embodiment will be described. FIG. 32 is a block diagram showing the configuration of the touch panel device according to this embodiment. As shown in FIG. 32, the touch panel device according to the present embodiment includes a touch panel 1, a drive section 4, a measurement section 5, a detection section 6, and a control section . The touch panel 1 includes multiple receiving electrodes 12 and multiple transmitting electrodes 14 .

The touch panel device according to the present embodiment is, for example, an electronic device equipped with the touch panel 1, such as a programmable display, mobile phone, smart phone, mobile music player, mobile game machine, TV, PC, digital camera, digital video.

The touch panel device according to the present embodiment is capable of detecting a touch by a user's finger, a conductive pen, or the like, and executes processing specified by the touch. The touch panel device according to this embodiment detects whether or not water is attached to the touch panel 1 based on the detection principle described above.

Note that the touch panel device according to the present embodiment may include members such as a communication section, an audio input section, and an audio output section, but these members are not illustrated because they are not related to the features of the invention.

The control unit 7 designates the transmission electrode 14 to which the voltage is applied to the driving unit 4 . The control unit 7 also instructs the measurement unit 5 to measure the amount of change in capacitance between the transmission electrode 14 and the reception electrode 12 .

The drive unit 4 applies a square-wave pulse voltage to the transmission electrode 14 to which the voltage is applied according to the instruction from the control unit 7 . At this time, the drive unit 4 connects the other transmission electrodes 14 to a fixed potential.

In accordance with the instruction from the control unit 7, the measuring unit 5 measures the change in the capacitance between the receiving electrode 12 and the transmitting electrode 14 to which the voltage is applied at that time based on the change in the potential generated in the receiving electrode 12. Measure quantity. Note that the amount of change measured by the measuring unit 5 is the above-described plus or minus value.

The control unit 7 provides the detection unit 6 with identification information of the transmission electrode 14 to which the voltage is applied. Then, the control unit 7 instructs the detection unit 6 to detect the amount of change measured by the measurement unit 5 .

The detection unit 6 detects the amount of change in capacitance for each receiving electrode 12 from the measurement unit 5 according to the instruction from the control unit 7 . Then, the detection unit 6 stores the detected amount of change in capacitance in association with the identification information of the transmission electrode 14 input from the control unit 7 .

After performing the above process for all the transmission electrodes 14, the control unit 7 instructs the detection unit 6 to perform water detection determination.

The detection unit 6 determines the presence or absence of water adhesion based on the amount of change in capacitance for each reception electrode 12, which is stored in association with each identification information of the transmission electrode 14, and outputs the determination result to the outside. .

The control unit 7 repeats the series of processes described above.

Next, the processing procedure of the method for determining the presence or absence of water adhesion according to this embodiment will be described. FIG. 27 is a flow chart showing a processing procedure of a method for determining presence/absence of water adhesion according to the present embodiment.

As shown in FIG. 27 , first, when all the amounts of change in capacitance acquired from the measurement unit 5 are signed values and are equal to or greater than a certain threshold value (Yes in S1), no water adheres (water none) (S5). The amount of change in capacitance due to water adhesion is smaller than the amount of change in capacitance due to finger touch (see FIGS. 12, 13, 14, 15, 17, and 18). , it is possible to determine that there is no adhesion of water if it is equal to or greater than a certain threshold value.

Here, it is preferable that the above-mentioned constant threshold value is a negative value and is smaller than the amount of capacitance change (negative value) due to the ghost caused by the finger.

More preferably, the constant threshold is a negative value that satisfies the following conditions (A) to (C).

(A) It is a value smaller than the amount of capacitance change (negative value) due to a ghost caused by a finger.

(B) A value larger than the amount of capacitance change (negative value) caused by the water W1 shown in FIG.

(C) A value larger than the amount of capacitance change (negative value) due to the ghost caused by water W1 and water W2 shown in FIGS. 17 and 18 .

For example, it is assumed that the detectable range of the capacitance change amount by the touch panel 1 is -127 to +127. The detection sensitivity of the touch panel 1 is adjusted so that the amount of change in capacitance that can be determined to be touched by a finger is about +60.

In this case, the amount of change in capacitance due to the ghost caused by two fingers is about -10.

The amount of change in capacitance caused by water is about -40.

The amount of change in capacitance due to ghosting caused by two waters is about -40.

The amount of change in capacitance caused by two connected waters is on the order of +40.

From the above, the constant threshold should be set to a value of about -12.

If all the amounts of change in capacitance obtained from the measurement unit 5 are signed values and are not equal to or greater than a certain threshold value (No in S1), the amount of change in capacitance obtained from the measurement unit 5 is transferred to the receiving electrode. 12, the sum is calculated along each receiving electrode 12 (S2).

If any of the values calculated in S2 described above is equal to or greater than a certain threshold value (Yes in S3), it is determined that there is no adhesion of water (no water) (S5). Since the total amount of capacitance change along the receiving electrode 12 due to water adhesion does not become a large positive value (see FIGS. 30 and 31), water adhesion does not occur if it is equal to or greater than a certain threshold value. It is possible to determine that

Finally, if none of the values calculated in S2 described above is equal to or greater than a certain threshold value (No in S3), it is determined that water is present (water is present) (S4).
[Modification]
This modified example is an embodiment that improves the accuracy of detecting a finger touch position in the original function of the touch panel 1 by using a differential amplifier. When touched with a finger, near the center of the finger, the distribution of the amount of change in capacitance becomes flat, and the accuracy of the numerical value for calculating the position of the center of the finger decreases. In contrast, when acquiring the difference in capacitance variation between adjacent receiving electrodes, the value of the difference can be sufficiently amplified and digitized. Also, the position of the center of the finger is the position where the sign of the difference value is inverted. Therefore, by using a differential amplifier, the touch position can be detected with high calculation accuracy.

Next, a touch panel device according to a modified example of the present invention will be described.

The difference between the modified example of the present invention and the first embodiment described above is that, as shown in FIG. The point is that 100 measurements are used. In (a) of FIG. 37, the measured value is represented by S, and the subscript value is represented in accordance with the subscript of the receiving electrode connected to the negative side of the differential amplifier.

In the present embodiment, the sum of the measured values for each of the receiving electrodes 12 is calculated instead of the sum of the capacitance variations for each of the receiving electrodes 12 . In the first embodiment, only one threshold is set for the total sum. Values with different positive and negative signs are calculated at both ends of a series of receiving electrodes in which the amount of change in capacitance occurs, on the side with the smaller number and the side with the larger number.

Therefore, in the present embodiment, two thresholds are set, one on the positive side and one on the negative side.

Specifically, as shown in (b) and (c) of FIG. 37, the difference in capacitance variation between the receiving electrode R1 and the receiving electrode R2 is the measured value S1, and the difference between the receiving electrode R2 and the receiving electrode R3 is the measured value S2, the difference in the capacitance change between the receiving electrode R3 and the receiving electrode R4 is the measured value S3, and the electrostatic capacitance between the receiving electrode R4 and the receiving electrode R5 is the measured value S2. The difference in capacitance variation is the measured value S4, and the difference in capacitance variation between the receiving electrode R5 and the receiving electrode R6 is the measured value S5. Measured values S1 to S5 are treated as measured values of the receiving electrodes R1 to R5, respectively.

The measured value S2 becomes a positive value and the measured value S4 becomes a negative value. in short,
Measured value S1+Measured value S2=Amount of change in capacitance of receiving electrode R2 Measured value S2+Measured value S3=Amount of change in capacitance of receiving electrode R3.

Next, the configuration of the touch panel device according to this embodiment will be described.

The control unit 7 instructs the driving unit 4 to drive the transmission electrode 14 to which the voltage is applied, and instructs the measuring unit 5 to measure the amount of change in capacitance.

The drive unit 4 applies a square-wave pulse voltage to the transmission electrode 14 to which the voltage is applied according to the instruction from the control unit 7 . At this time, the other transmission electrodes 14 are connected to a fixed potential.

In accordance with the instruction from the control unit 7, the measuring unit 5 measures the change in the capacitance between the receiving electrode 12 and the transmitting electrode 14 to which the voltage is applied at that time based on the change in the potential generated in the receiving electrode 12. The difference in quantity between adjacent receiving electrodes 12 is measured as a signed value. This measurement result is called a measurement value. When the receiving electrodes 12 are numbered in ascending order among the adjacent receiving electrodes 12, the measured value is associated with the number of the receiving electrode 12 having the smaller number, and is treated as the measured value of that receiving electrode 12. The difference is obtained by inputting the potential of the receiving electrode 12 with a smaller number to the negative side of the differential amplifier, and inputting the potential of the receiving electrode 12 with a larger number into the positive side of the same differential amplifier, and obtaining the output of the differential amplifier. obtained by obtaining

The control unit 7 provides the detection unit 6 with the identification information of the transmission electrode 14 to which the voltage is applied, and instructs the measurement unit 5 to detect the measurement result. The detection unit 6 detects the measured value from the measurement unit 5 according to the instruction from the control unit 7 , and stores it in association with the identification information of the transmission electrode 14 input from the control unit 7 .

After performing the above processing for all the transmission electrodes 14, the control unit 7 instructs the detection unit 6 to perform water detection determination.

The detection unit 6 determines the presence or absence of water adhesion using the measurement value for each reception electrode 12 stored in association with the identification information of the transmission electrode 14, and outputs the determination result to the outside.

The control unit 7 repeats the series of processes described above.

Next, the processing procedure of the method for determining the presence or absence of water adhesion according to this embodiment will be described. FIG. 29 is a flow chart showing a processing procedure of a method for determining presence/absence of water adhesion according to the present embodiment.

As shown in FIG. 29, first, for each measurement value obtained from the measurement unit 5 associated with the identification information of the transmission electrode 14, the sum of adjacent measurement values is calculated from the reception electrode 12 side with the smaller number. If all of the sum values are signed values and are equal to or greater than a certain threshold value (Yes in S11), it is determined that water is not adhered (S16).

Here, the value of each sum described above is the value of the amount of change in capacitance. If there is a touch with a finger, the value of each sum (amount of change in capacitance) will be a large positive value, while it will be a small negative value due to the ghost caused by the finger. In S16, if the value of each sum is positive and large or negative and small, it is determined that water is not adhered. Therefore, the determination is performed using a threshold (threshold as a value of the amount of change in capacitance) that can eliminate ghosts caused by fingers as well.

If all of the above sum values are signed values and are not equal to or greater than a certain threshold value (No in S11), the sum of the measured values obtained from the measuring unit 5 is calculated for each receiving electrode 12 (S12).

If none of the values calculated in S12 described above exceeds the positive first threshold value (No in S13), it is determined that water has adhered (S14).

If any of the values calculated in S12 described above exceeds the first positive threshold (Yes in S13), the second negative threshold among the values calculated in S12 described above (Yes in S15), it is determined that there is no adhesion of water (S16).

If some of the values calculated in S12 described above exceed the second threshold value (Yes in S15), it is determined that water adheres (S14).

Here, outside the touch of the finger (boundary portion between the touched area and the outside of the touched area), the measured value becomes a large positive value or a large negative value. When there is a finger touch, both positive and negative large values will appear. On the other hand, outside the water (the boundary between the area where water is attached and the area outside), the measured value is a positive or negative value, but the absolute value is usually small. . Depending on the state of adhesion of water, even if the distribution of "variation in capacitance" becomes steep and a large measured value can be obtained, a pair of positive and negative measured values with large absolute values will appear. never.

(effect)
(1) Erroneous detection due to noise The amount of change in capacitance caused by noise does not occur evenly between plus and minus, but occurs unbalanced. Therefore, the sum of the amount of capacitance change caused by noise along the receiving electrode 12 becomes a large positive value. can.

(2) Erroneous detection due to multi-touch Even if the detection sensitivity is increased and the ghost generated by the touch with two fingers shows a large value that can be detected by the receiving electrode 12, the amount of change in the capacitance of the receiving electrode Summation along 12 shows a large value on the positive side. As a result, it can be seen that the water is not due to the adhesion of water, so that erroneous detection can be prevented.

(3) Erroneous Detection of Touching Water with a Finger Regardless of the pattern of capacitance variation along the transmitting electrode, the total amount of variation in capacitance caused by the adhesion of water along the receiving electrode 12 is , cannot be a large positive value. For this reason, it can be found that the cause is due to adhesion of water, and erroneous detection can be prevented.

In the above description, a square wave pulse having a predetermined positive potential from 0 V is applied to the transmitting electrode 14, and the maximum positive value of the potential induced in the receiving electrode 12 is measured. The fact that the capacitance between the receiving electrode 12 can be measured is utilized.

However, based on the same principle, a square wave pulse having a negative polarity may be used, and the stationary potential of the square wave pulse is not limited to 0V. In that case, even if the polarity of the potential induced in the receiving electrode 12 is negative, by taking into account the polarity and magnitude of the potential induced in the receiving electrode 12 with and without finger touch. , the amount of change in capacitance can be detected by exactly the same principle as described above.

In addition, it is not necessary to use the stable maximum value of the potential induced in the receiving electrode 12 as a measurement value, and the change in the capacitance induced in the receiving electrode 12 is measured so as to determine the amount of change over time. may Also, the driving voltage applied to the transmitting electrode 14 need not be a square wave pulse, and may be, for example, a sine wave with a higher frequency. In addition, any technique may be used as long as the mutual capacitance between the transmitting electrode 14 and the receiving electrode 12 or the amount of change thereof can be measured.

[Coordinate calculation method in mutual capacitance method]
According to the method described above, it is possible to detect the presence or absence of water adhesion on the mutual capacitance touch panel 1 . The inventors of the present application have found a method of accurately calculating touched coordinates even when water is attached. Description will be made below with reference to FIGS.

FIG. 36 is a functional block diagram showing the main configuration of the coordinate calculation device 20 according to this embodiment. As shown in FIG. 36 , the coordinate calculation device 20 includes a detection section 6 and a control section 7 . The detection unit 6 includes a first total sum calculation unit 611 , a second total sum calculation unit 612 , a first coordinate calculation unit 621 , a second coordinate calculation unit 622 and a two-dimensional coordinate calculation unit 623 . Also, the control unit 7 includes a switching unit 71 .

The first summation calculator 611 calculates the sum of the amount of change in capacitance when the drive voltage is applied from each transmission electrode 14 to each reception electrode 12 . A specific description will be given with reference to FIG. FIG. 37 is a diagram for explaining the sum total of variations in capacitance. In the example shown in FIG. 37, T1 to T8 are shown as the transmitting electrodes 14, and R1 to R14 are shown as the receiving electrodes 12. In FIG. It should be noted that the numbers of the transmitting electrodes 14 and the numbers of the receiving electrodes 12 here are just an example, and the number is not limited to this.

First, the first summation calculating unit 611 calculates, for the receiving electrode 12 (R1), the amount of change in capacitance when the driving voltage is applied from the transmitting electrode 14 (T1) and the driving voltage from the transmitting electrode 14 (T2). The amount of change in capacitance when applied, the amount of change in capacitance when the drive voltage is applied from the transmission electrode 14 (T3), . . . , when the drive voltage is applied from the transmission electrode 14 (T8) , and the sum total of changes in capacitance when the drive voltage is applied from each transmission electrode 14 is calculated. This is performed for all the receiving electrodes 12 such as the receiving electrode 12 (R2), the receiving electrode 12 (R3), .

The first coordinate calculation unit 621 calculates the first coordinates of the touch position based on the sum of the capacitance change amounts calculated by the first sum calculation unit 611 . The first coordinates are coordinates in the direction in which the transmission electrodes 14 are connected.

After the switching unit 71 (to be described later) switches between the transmitting electrodes 14 and the receiving electrodes 12 , the second summation calculating unit 612 calculates the static electricity generated when the driving voltage is applied from each transmitting electrode 14 for each receiving electrode 12 . Calculate the total amount of capacitance change. A specific description will be given with reference to FIG. FIG. 38 is a diagram for explaining the total amount of change in capacitance after switching between the transmitting electrode 14 and the receiving electrode 12. In FIG. In the example shown in FIG. 38, T'1 to T'14 are shown as the transmission electrodes 14 after switching, and R'1 to R'8 are shown as the reception electrodes 12 after switching.

The second summation calculator 612 first calculates the amount of change in capacitance when the drive voltage is applied from the transmission electrode 14 (T'1) to the reception electrode 12 (R'1), the transmission electrode 14 (T' 2), the amount of change in capacitance when the drive voltage is applied from the transmission electrode 14 (T'3), the amount of change in capacitance when the drive voltage is applied from the transmission electrode 14 (T'3), ..., the transmission electrode 14 (T' From 14), the total amount of change in capacitance when the drive voltage is applied from each transmission electrode 14 is calculated. This is done for all the receiving electrodes 12 such as the receiving electrode 12 (R'2), the receiving electrode 12 (R'3), and so on.

The second coordinate calculation unit 622 calculates the second coordinates of the touch position based on the sum of the capacitance change amounts calculated by the second sum calculation unit 612 . The second coordinates are coordinates in the direction in which the transmitting electrodes 14 after switching by the switching unit 71 are connected, that is, the coordinates in the direction orthogonal to the coordinates calculated by the first coordinate calculation unit 621 .

The two-dimensional coordinate calculation unit 623 calculates two-dimensional coordinates indicating the touch position on the touch panel 1 based on the first coordinates calculated by the first coordinate calculation unit 621 and the second coordinates calculated by the second coordinate calculation unit 622. .

(The reason why the coordinates can be calculated even if water is attached)
As described above with reference to FIGS. 29 to 31, the influence of the adhesion of water on the amount of change in capacitance appears for each transmission electrode 14. FIG. However, as described with reference to FIG. 31, when the sum of all the transmission electrodes 14 is calculated, the amount of change in capacitance caused by the adhesion of water is canceled out.

Therefore, the sum of the amount of change in capacitance calculated by the first summation calculation unit 611 and the second summation calculation unit 612 shows the result of canceling out the amount of change in capacitance due to the adhesion of water. Become. Therefore, the first coordinates calculated by the first coordinate calculation unit 621 using the calculation results of the first total sum calculation unit 611 and the second coordinate calculation unit 622 using the calculation results of the second sum calculation unit 612 Since the two coordinates are the coordinates calculated as a result of canceling out the influence of adhesion of water, the two-dimensional The coordinates can be said to be accurate coordinates where water is not affected by adhesion.

FIG. 39 shows an example of touching from above the adhering water. As shown in FIG. 39, when water adheres and the area is touched with a finger F, the amount of change in capacitance of each transmission electrode 14 is affected by water adhesion. However, if the total sum of all the transmitting electrodes 14 is calculated, the effect of adhering water is canceled out, so that the correct touched coordinates can be calculated after all.

Here, an example of the case of touching from the top of the adhering water is shown, but the same applies to the case of touching a region different from the adhering water. Since the influence of adhering water is canceled by calculating the total amount of change in capacitance, accurate coordinates can be calculated without being affected by water.

(Processing flow)
Next, the flow of processing in the coordinate calculation device 20 will be described with reference to FIG. FIG. 40 is a flow chart showing the flow of processing in the coordinate calculation device 20. As shown in FIG.

As shown in FIG. 40, the measuring unit 5 first measures the amount of change in capacitance between the transmitting electrode 14 and the receiving electrode 12 for each of the transmitting electrode 14 and the receiving electrode 12 (S101). Then, the first summation calculator 611 calculates the sum of the amount of change in capacitance between the transmission electrode 14 and the reception electrode 12 along the reception electrode 12 (S102). Then, the first coordinate calculation unit 621 calculates the first coordinates of the touch position based on the sum calculated by the first sum calculation unit 611 (S103).

Next, the switching unit 71 switches the transmitting electrode 14 and the receiving electrode 12, and changes the transmitting electrode 14 to the receiving electrode 12 and the receiving electrode 12 to the transmitting electrode 14 (S104).

Then, the measuring unit 5 measures the amount of change in capacitance between the transmitting electrode 14 and the receiving electrode 12 after switching for each of the transmitting electrode 14 and the receiving electrode 12 (S105). Then, the second total sum calculator 612 calculates the sum of the amount of change in capacitance between the transmitter electrode 14 and the receiver electrode 12 along the receiver electrode 12 (S106). Next, the second coordinate calculation unit 622 calculates the second coordinates of the touch position based on the sum calculated by the second sum calculation unit 612 (S107). Finally, the two-dimensional coordinate calculator 623 calculates the two-dimensional coordinates of the touch position on the touch panel 1 based on the first coordinates and the second coordinates (S108).

[Coordinate calculation method in mutual capacitance method-2]
Next, with reference to FIGS. 41 to 45, a method of calculating coordinates using the differences described above with reference to FIGS. 34 and 35 will be described.

FIG. 41 is a functional block diagram showing the main configuration of a coordinate calculation device 20' according to this method. As shown in FIG. 41, the coordinate calculation device 20' includes a detection unit 6' and a control unit 7. The detection unit 6' includes a first difference calculation unit 631, a second difference calculation unit 632, a first average calculation unit A section 641 , a second average value calculation section 642 , a third sum calculation section 613 , a fourth sum calculation section 614 , a first coordinate calculation section 621 , a second coordinate calculation section 622 , and a two-dimensional coordinate calculation section 623 are included. Note that the first average value calculator 641 and the second average value calculator 642 are not essential components.

The first difference calculator 631 calculates the sum of the differences between adjacent receiving electrodes 12 in the amount of capacitance change between the receiving electrode 12 and each transmitting electrode 14 along the receiving electrode 12 .

The second difference calculation unit 632 calculates the amount of change in capacitance between the receiving electrode 12 and each transmitting electrode 14 along the receiving electrode 12 after switching between the transmitting electrode 14 and the receiving electrode 12 by the switching unit 71. , the sum of the differences between adjacent receiving electrodes 12 is calculated.

The first average value calculator 641 calculates the first average value, which is the average value of the calculated values between the adjacent receiving electrodes 12 calculated by the first difference calculator 631 .

The second average value calculator 642 calculates a second average value, which is the average value of the calculated values between the adjacent receiving electrodes 12 calculated by the second difference calculator 632 .

The third summation calculation unit 613 calculates the sum of the amount of change in capacitance between the reception electrode 12 and each transmission electrode 14 along the reception electrode 12 from the result calculated by the first difference calculation unit 631. do.

In addition, the third summation calculation unit 613 calculates the summation of the amount of change in capacitance using a value obtained by subtracting the first average value from the result calculated by the first difference calculation unit 631 .

The fourth total sum calculation unit 614 calculates the sum of the amount of change in capacitance between the reception electrode 12 and each transmission electrode 14 along the reception electrode 12 from the result calculated by the second difference calculation unit 632. do.

In addition, the fourth total sum calculation unit 614 calculates the sum of the amount of change in capacitance using a value obtained by subtracting the second average value from the result calculated by the second difference calculation unit 632 .

The first coordinate calculator 621 calculates the first coordinates indicating the touch position in the transmission electrode direction, which is the direction in which the transmission electrodes 14 are connected, from the result calculated by the third summation calculator 613 .

The second coordinate calculation unit 622 calculates second coordinates indicating the touch position in the transmission electrode direction, which is the direction in which the transmission electrodes 14 after switching are connected, from the result calculated by the fourth total sum calculation unit 614 .

[Correction-1]
The correction used in this method will be described with reference to FIGS. 34 and 42-44. When the measured difference values are S1 to S11 shown in FIG. 34(c), the amount of change in the capacitance of the receiving electrodes 12 (R1 to R12) is the value shown in FIG. 34(b). That is, R1=0, R2=R1+S1, R3=R2+S2, R4=R3+S3, R5=R4+S4, and so on.

However, the balance may be lost depending on the performance of the differential amplifier. Description will be made with reference to FIG. FIG. 42(a) is a diagram showing an example of measured values when the balance of the differential amplifier is poor. The example of FIG. 42(a) shows the case where the balance of the differential amplifier is shifted to the positive side. When the measured value is as shown in FIG. 42(a), the amount of change in capacitance calculated from this measured value is as shown in FIG. 42(b). In other words, the amount of change in the capacitance rises to the right, making it impossible to accurately calculate the coordinates of the touch position. In the example of FIG. 42(b), two locations R4 and R12 appear as touch value coordinates.

Therefore, the first average value calculator 641 calculates the first average value, which is the average value of the measured values (the calculation results of the first difference calculator 631), as shown in FIG. 43(a). Then, as shown in (b) of FIG. 43, the third summation calculator 613 performs correction by subtracting the first average value from the result calculated by the first difference calculator 631 . Then, the amount of change in capacitance is calculated using the corrected value ((c) in FIG. 43). Thereby, the coordinate calculation can be performed in consideration of the imbalance of the differential amplifier.

The same processing is performed for the second average value calculator 642 and the fourth total sum calculator 614 .

[Correction-2]
Further, when the amount of change in capacitance calculated by the third total sum calculation unit 613 or the fourth total sum calculation unit 614 has a negative value, the maximum value is not an appropriate value, and the coordinates of the touch position are calculated. It may not be calculated.

Therefore, when the calculated minimum value of the amount of change in capacitance is negative, the third total sum calculation unit 613 or the fourth total sum calculation unit 614 uses the value added by the negative value as the calculation result.

That is, as shown in FIG. 44(b), when the calculated minimum value of the amount of change in capacitance is negative, as shown in FIG. Calculated result. As a result, the maximum value of the amount of change in capacitance is also increased by the minus value, making it possible to accurately calculate the coordinates of the touch position.

[Process flow]
Next, the flow of processing in the coordinate calculation device 20' will be described with reference to FIG. FIG. 45 is a flow chart showing the flow of processing in the coordinate calculation device 20'. Note that FIG. 45 does not include the above-described correction processing.

As shown in FIG. 45 , first, the measuring unit 5 measures the difference between the amounts of change in capacitance between the transmitting electrode 14 and the receiving electrode 12 adjacent to each other for each transmitting electrode 14 and each receiving electrode 12 . is measured (S201). Next, the first difference calculator 631 calculates the sum of the differences in capacitance variation between the transmitter electrode 14 and the receiver electrode 12 along the receiver electrode 12 (S202). . Then, the third summation calculation unit 613 calculates the summation of the amount of change in capacitance between the transmission electrode 14 and the reception electrode 12 for each reception electrode 12 from the summation of the differences (S203). Then, the first coordinate calculation unit 621 calculates the first coordinates of the touch position based on the sum calculated by the third sum calculation unit 613 (S204).

Next, the switching unit 71 switches between the transmitting electrode 14 and the receiving electrode 12 to change the transmitting electrode 14 to the receiving electrode 12 and the receiving electrode 12 to the transmitting electrode 14 (S205).

Next, the measuring unit 5 measures the difference between the adjacent receiving electrodes 12 in the amount of change in capacitance between the transmitting electrode 14 and the receiving electrode 12 after switching for each of the transmitting electrode 14 and the receiving electrode 12. (S206). Then, the second difference calculator 632 calculates the sum of the differences in capacitance variation between the transmitter electrode 14 and the receiver electrode 12 along the receiver electrode 12 (S207). Then, the fourth total sum calculator 614 calculates the sum of the amount of change in capacitance between the transmitting electrode 14 and the receiving electrode 12 for each receiving electrode 12 from the sum of the differences (S208). Then, the second coordinate calculation unit 622 calculates the second coordinates of the touch position based on the sum calculated by the fourth sum calculation unit 614 (S209). Finally, the two-dimensional coordinate calculator 623 calculates the two-dimensional coordinates of the touch position on the touch panel 1 based on the first coordinates and the second coordinates (S210).

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1 touch panel 14, T1 to T8, T'1 to T'14 transmission electrode 12, R1 to R12, R'1 to R'8 reception electrode 4 drive section 5 measurement section 6, 6' detection section 7 control section 11 front cover 15 substrate 20, 20' coordinate calculation device 20
611 First summation calculation unit 612 Second summation calculation unit 613 Third summation calculation unit 614 Fourth summation calculation unit 621 First coordinate calculation unit 622 Second coordinate calculation unit 623 Two-dimensional coordinate calculation unit 631 First difference calculation unit 632 2 difference calculator 641 first average calculator 642 first average calculator 71 switching unit

Claims (5)

A coordinate calculation device for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method,
a first difference calculation unit that calculates the sum of differences in capacitance variation between the receiving electrode and each transmitting electrode along the receiving electrode, between adjacent receiving electrodes;
a third summation calculation unit that calculates the sum of the amount of change in capacitance between the reception electrode and each transmission electrode along the reception electrode from the result calculated by the first difference calculation unit;
a first coordinate calculation unit that calculates a first coordinate indicating a touch position in a transmission electrode direction, which is a direction in which the transmission electrodes are connected, from the result calculated by the third summation calculation unit;
a switching unit that switches between the transmitting electrode and the receiving electrode;
Along the post-switching receiving electrode, which is the receiving electrode after switching by the switching unit, the capacitance between the post-switching receiving electrode and the post-switching transmitting electrode, which is the transmitting electrode after switching by the switching unit. a second difference calculator that calculates the sum of the differences between adjacent post-switching reception electrodes in the amount of change;
Fourth total sum calculation for calculating the sum of the amount of change in capacitance between the post-switching reception electrode and each post-switching transmission electrode along the post-switching reception electrode from the result calculated by the second difference calculation unit Department and
a second coordinate calculation unit that calculates a second coordinate indicating a touch position in a direction of the post-switching transmission electrodes, which is a direction in which the post-switching transmission electrodes are connected, from the result calculated by the fourth summation calculation unit;
a two-dimensional coordinate calculation unit that calculates two-dimensional coordinates of a touch position on the touch panel from the first coordinates and the second coordinates;
a first average value calculation unit that calculates a first average value that is an average value of the calculated values for each of the adjacent receiving electrodes calculated by the first difference calculation unit;
a second average value calculating unit that calculates a second average value that is an average value of the calculated values for each of the adjacent receiving electrodes calculated by the second difference calculating unit ;
The third summation calculation unit uses a value obtained by subtracting the first average value from the result calculated by the first difference calculation unit to calculate the summation of the amount of change in the capacitance,
The coordinate calculation device, wherein the fourth summation calculation unit calculates the summation of the amount of change in the capacitance using a value obtained by subtracting the second average value from the result calculated by the second difference calculation unit. . A coordinate calculation device for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method,
a first difference calculation unit that calculates the sum of differences in capacitance variation between the receiving electrode and each transmitting electrode along the receiving electrode, between adjacent receiving electrodes;
a third summation calculation unit that calculates the sum of the amount of change in capacitance between the reception electrode and each transmission electrode along the reception electrode from the result calculated by the first difference calculation unit;
a first coordinate calculation unit that calculates a first coordinate indicating a touch position in a transmission electrode direction, which is a direction in which the transmission electrodes are connected, from the result calculated by the third summation calculation unit;
a switching unit that switches between the transmitting electrode and the receiving electrode;
Along the post-switching receiving electrode, which is the receiving electrode after switching by the switching unit, the capacitance between the post-switching receiving electrode and the post-switching transmitting electrode, which is the transmitting electrode after switching by the switching unit. a second difference calculator that calculates the sum of the differences between adjacent post-switching reception electrodes in the amount of change;
Fourth total sum calculation for calculating the sum of the amount of change in capacitance between the post-switching reception electrode and each post-switching transmission electrode along the post-switching reception electrode from the result calculated by the second difference calculation unit Department and
a second coordinate calculation unit that calculates a second coordinate indicating a touch position in a direction of the post-switching transmission electrodes, which is a direction in which the post-switching transmission electrodes are connected, from the result calculated by the fourth summation calculation unit;
a two-dimensional coordinate calculation unit that calculates two-dimensional coordinates of a touch position on the touch panel from the first coordinates and the second coordinates ,
If the minimum value of the amount of change in capacitance calculated by the third summation calculation unit is negative, the value added by the negative value is the calculation result of the third summation calculation unit,
The coordinate calculating device, wherein when the minimum value of the amount of change in capacitance calculated by the fourth summation calculating section is negative, a value obtained by adding the negative value is used as the calculation result of the fourth summation calculating section. A touch panel comprising the coordinate calculation device according to claim 1 or 2 . A coordinate calculation method for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method,
a first difference calculating step of calculating the sum of the differences between adjacent receiving electrodes in the amount of change in capacitance between the receiving electrode and each transmitting electrode along the receiving electrode;
a third summation calculation step of calculating the sum of the amount of change in capacitance between the reception electrode and each transmission electrode along the reception electrode from the result calculated in the first difference calculation step;
a first coordinate calculation step of calculating a first coordinate indicating a touch position in a transmission electrode direction, which is a direction in which the transmission electrodes are connected, from the result calculated in the third summation calculation step;
a switching step of switching between the transmitting electrode and the receiving electrode;
Capacitance between the post-switching reception electrode and each post-switching transmission electrode that is the transmission electrode after switching in the switching step along the post-switching reception electrode that is the reception electrode that is switched in the switching step A second difference calculation step of calculating the sum of differences between adjacent receiving electrodes in the amount of change in
Fourth total sum calculation for calculating the sum of the amount of change in capacitance between the post-switching reception electrode and each post-switching transmission electrode along the post-switching reception electrode from the result calculated in the second difference calculation step a step;
a second coordinate calculation step of calculating a second coordinate indicating a touch position in a direction of the post-switching transmission electrodes, which is a direction in which the post-switching transmission electrodes are connected, from the results calculated in the fourth total sum calculation step;
a two-dimensional coordinate calculation step of calculating the two-dimensional coordinates of the touch position on the touch panel from the first coordinates and the second coordinates ,
moreover,
A first average value calculating step of calculating a first average value that is an average value of the calculated values for each of the adjacent receiving electrodes calculated in the first difference calculating step;
a second average value calculating step of calculating a second average value that is an average value of the calculated values for each of the adjacent receiving electrodes calculated by the second difference calculating step;
In the third total sum calculation step, the sum of the capacitance variations is calculated using a value obtained by subtracting the first average value from the result calculated in the first difference calculation step,
In the fourth total sum calculation step, a value obtained by subtracting the second average value from the result calculated in the second difference calculation step is used to calculate the sum total of the capacitance change amounts. Method. A coordinate calculation method for calculating coordinates indicating a touch position on a touch panel capable of touch detection by a mutual capacitance method,
a first difference calculating step of calculating the sum of the differences between adjacent receiving electrodes in the amount of change in capacitance between the receiving electrode and each transmitting electrode along the receiving electrode;
a third summation calculation step of calculating the sum of the amount of change in capacitance between the reception electrode and each transmission electrode along the reception electrode from the result calculated in the first difference calculation step;
a first coordinate calculation step of calculating a first coordinate indicating a touch position in a transmission electrode direction, which is a direction in which the transmission electrodes are connected, from the result calculated in the third summation calculation step;
a switching step of switching between the transmitting electrode and the receiving electrode;
Capacitance between the post-switching reception electrode and each post-switching transmission electrode that is the transmission electrode after switching in the switching step along the post-switching reception electrode that is the reception electrode that is switched in the switching step A second difference calculation step of calculating the sum of differences between adjacent receiving electrodes in the amount of change in
Fourth total sum calculation for calculating the sum of the amount of change in capacitance between the post-switching reception electrode and each post-switching transmission electrode along the post-switching reception electrode from the result calculated in the second difference calculation step a step;
a second coordinate calculation step of calculating a second coordinate indicating a touch position in a direction of the post-switching transmission electrodes, which is a direction in which the post-switching transmission electrodes are connected, from the results calculated in the fourth total sum calculation step;
a two-dimensional coordinate calculation step of calculating the two-dimensional coordinates of the touch position on the touch panel from the first coordinates and the second coordinates ,
If the minimum value of the amount of change in capacitance calculated in the third summation calculation step is negative, the value added by the negative value is the calculation result of the third summation calculation step,
The coordinate calculation method, wherein when the minimum value of the capacitance change amount calculated in the fourth total sum calculation step is negative, a value obtained by adding the negative value is used as the calculation result of the fourth sum calculation step.

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