WO2013046513A1

WO2013046513A1 - Signal processing circuit for touch sensor and touch sensor

Info

Publication number: WO2013046513A1
Application number: PCT/JP2012/004610
Authority: WO
Inventors: 直人島高; 英明笹原
Original assignee: 旭化成エレクトロニクス株式会社
Priority date: 2011-09-30
Filing date: 2012-07-19
Publication date: 2013-04-04
Also published as: JP5715703B2; TW201316236A; JPWO2013046513A1

Abstract

The purpose of the present invention, with regard to signal processing for a touch panel, is to improve the signal-to-noise ratio by enabling the noise generated when a finger is brought into contact with a touch panel to be lessened. A selection circuit (2) selects two from among Y-lines (Y1-Y8) to serve as detection lines, and also selects at least two lines from among X-lines (X1-X8) to serve as detection lines, in accordance with the selection of one from among a plurality of detection patterns determined in accordance with a transformation matrix. A drive circuit (3) supplies a voltage to selected drive lines. A voltage detection circuit (4) detects the difference between one electrical potential and another electrical potential generated on the selected detection lines. A capacity calculation circuit (6) carries out a computation on the basis of the respective detected electrical potential differences and the transformation matrix, and respectively calculates the electrostatic capacitance of the difference between the electrostatic capacitance of each intersecting part between one selected drive line and a selected detection line, and between the electrostatic capacitance of each intersecting part between another selected drive line and each selected detection line.

Description

Touch sensor signal processing circuit and touch sensor

The present invention relates to a signal processing circuit of a touch sensor including a capacitive touch panel.

Conventionally, inventions described in Patent Document 1 and Patent Document 2 are known as inventions related to touch sensors including this type of touch panel.
First, the invention of Patent Document 1 includes a plurality of first electrodes extending in a first direction, a plurality of second electrodes extending in a second direction different from the first direction, a drive circuit, a detection circuit, And a coordinate position calculation circuit.

The drive circuit sequentially selects two first electrodes from the plurality of first electrodes, supplies a voltage having a higher potential than the reference voltage to one of the two selected first electrodes, and supplies the other to the reference Supply voltage. The detection circuit includes a capacitance A between the selected second electrode and the first electrode supplied with the high potential voltage, and the selected second electrode and the first electrode supplied with the reference voltage. A capacitance difference (A−B) with the capacitance B between the two is detected. Further, the coordinate position calculation circuit calculates the touch position of the observer on the touch panel based on the selected positions of the first electrode and the second electrode and the capacitance difference (AB).

Next, the invention of Patent Document 2 is a signal processing circuit for a touch sensor that detects a touch position on a touch panel, and includes a drive circuit, a multiplexer, two reference capacitors, and a charge amplifier. .
The drive circuit selects two drive lines from a plurality of drive lines extending in one direction on the substrate, and supplies an AC drive voltage to the selected drive lines. Further, the multiplexer selects two sense lines from a plurality of sense lines on the substrate extending so as to intersect with the plurality of drive lines.

Further, the charge amplifier uses a differential amplifier, and has capacitance values A1 and A2 between two sense lines selected by the multiplexer and two drive lines selected by the drive circuit, and two reference capacitances. An output voltage corresponding to the difference between the values B1 and B2 is output.
In the signal processing circuit according to the invention of Patent Document 2, the touch position is detected based on the output voltage output from the charge amplifier.

Japanese Unexamined Patent Publication No. 2009-15489 JP 2010-282539 A

According to the invention described in Patent Document 1, it is possible to cancel a parasitic capacitance and detect a small inter-electrode capacitance, and to realize a high-resolution touch sensor with a large number of electrodes. However, noise generated when a finger touches the touch panel cannot be reduced (suppressed).
On the other hand, according to the invention described in Patent Document 2, since differential amplification is performed by the charge amplifier, noise generated when a finger touches the touch panel can be reduced. However, there is a problem that an output is not output when an object to be detected such as a finger comes just between the two electrodes, and it cannot be distinguished from a non-touch time.

Under such circumstances, a new appearance of the signal processing circuit of the touch sensor that adopts the new signal processing is desired for the signal processing of the touch sensor.
Furthermore, when a signal processing circuit of a touch sensor newly appears, it is desired to reduce noise generated when a finger touches the touch panel and to improve S / N.

Therefore, an object of the present invention is to provide a signal processing circuit for a touch sensor that employs new signal processing with respect to the signal processing of the touch sensor.
Another object of the present invention relates to signal processing of a touch sensor, which can reduce noise generated when a finger touches the touch panel and can improve S / N. It is to provide a signal processing circuit of a sensor.

One embodiment of the present invention is a touch sensor including a touch panel including a plurality of first lines and a plurality of second lines arranged so as to intersect the plurality of first lines via an insulating layer. A signal processing circuit having a first drive terminal and a second drive terminal, a first detection terminal and a second detection terminal, and an output terminal, wherein the first drive terminal and the second drive terminal The difference between the first capacitance connected between one detection terminal and the second capacitance connected between the second drive terminal and the first detection terminal is expressed as a first difference. The capacitance difference is obtained as a third capacitance connected between the first drive terminal and the second detection terminal, and is connected between the second drive terminal and the second detection terminal. The difference from the fourth capacitance is obtained as the second capacitance difference, and the first capacitance difference and the second capacitance difference are obtained. A capacitance measuring circuit that converts a difference from the quantity difference into a predetermined signal and outputs the selected signal, and one or more lines are selected as a first drive line group from the plurality of first lines, or the first In addition to one drive line group, zero or more lines different from the first drive line group are selected as a second drive line group, and the first drive line group is connected to the first drive terminal. And connecting the second drive line group to the second drive terminal and selecting zero or more lines as the first detection line group from the plurality of second lines, One or more lines different from the first detection line group are selected as a second detection line group, the first detection line group is connected to the first detection terminal, and the second detection line group is selected. And a selection circuit for connecting the second detection terminal to the second detection terminal. A signal processing circuit of a touch sensor.

In the above configuration, each time the detection circuit is selected from among a plurality of detection patterns determined according to a predetermined conversion matrix, the selection circuit is selected according to the selected detection pattern. At least one line is selected as the first drive line group from the plurality of second lines, and at least one line different from the first drive line group is used as the second drive line group. It may be a choice.

Further, an operation is performed based on the output signal of the capacitance measuring circuit and the conversion matrix, and each intersection of the selected first drive line group and the selected first and second detection line groups. And a corresponding difference in capacitance between the selected second drive line group and the selected first and second detection line groups corresponding to each other. Capacitance calculation circuits for calculating the respective capacitances may be provided.

In the above configuration, each time the detection circuit is selected from among a plurality of detection patterns determined according to a predetermined conversion matrix, the selection circuit is selected according to the selected detection pattern. One or more lines are selected as the first drive line group from the plurality of first lines, the selected first drive line group is connected to the first drive terminal, and the first drive line group is selected. A first offset adjusting capacitor having a predetermined capacitance value is connected between the second drive terminal and the first detection terminal, and the second drive terminal and the second detection terminal are connected in advance. A second offset adjustment capacitor having a predetermined capacitance value may be connected.

Further, the calculation of the capacitance is performed based on the output signal of the capacitance measuring circuit and the conversion matrix, and the capacitance at each intersection of the selected drive line and each selected detection line is calculated. A circuit may be provided.
In the above configuration, the transformation matrix may be a Hadamard transformation matrix.
Further, the Hadamard transform matrix has n rows × n columns (n = 2, multiple of 4), the plurality of detection patterns are n detection patterns, and the first and second detection lines to be selected are selected. The total number of lines belonging to the group may be n.

In the above-described configuration, each time a driving pattern is selected from among a plurality of driving patterns determined according to a predetermined conversion matrix, the selection circuit according to the selected driving pattern, One or more lines are selected as a first drive line group from among the plurality of first lines, and zero or more different from the first drive line group among the plurality of first lines. Is selected as the second drive line group, and each time one detection pattern is selected from among a plurality of detection patterns determined according to the predetermined conversion matrix, the selected detection pattern Accordingly, one or more lines are selected as a first detection line group from the plurality of second lines, and the first detection line group is the first detection line group among the plurality of second lines. 0 or more different It may be one that selects the in as second detection line group.

Further, an operation is performed based on the output signal of the capacitance measuring circuit and the conversion matrix, and each capacitance of the capacitance matrix formed at the intersection of the plurality of first lines and the plurality of second lines is calculated. A capacity calculation circuit for calculating the capacity may be provided.
In the above configuration, the transformation matrix may be a Hadamard transformation matrix.

Further, when the Hadamard transform matrix is m rows × m columns (m = 2, a multiple of 4) in the first direction and n rows × n columns (n = 2, a multiple of 4) in the second direction. The combination of the drive pattern and the detection pattern is (m × n), and the total number of lines belonging to the selected first and second drive line groups is m according to each drive pattern and detection pattern. The total number of lines belonging to the selected first and second detection lines may be n.

In the above configuration, the selection circuit changes, for each of the plurality of drive patterns, a line connected to the first drive terminal and a line connected to the second drive terminal, and the first drive terminal and The line connected to the first detection terminal and the line connected to the second detection terminal may be changed according to the change of the line connected to the second drive terminal.

In the above configuration, the selection circuit changes the connection of the line selected as the line connected to the first drive terminal to the first drive terminal to the connection to the first detection terminal, and The connection of the line selected as the line connected to the second drive terminal to the connection to the second detection terminal is changed to the connection to the second detection terminal, and the line selected as the line connected to the first detection terminal is changed. The connection to the first detection terminal is changed to the connection to the first drive terminal, and the connection to the second detection terminal of the line selected as the line to be connected to the second detection terminal is changed to the second. The connection to the drive terminal may be changed.

In the above configuration, the transformation matrix uses a first transformation matrix and a second transformation matrix, and any one of the first transformation matrix and the second transformation matrix is the plurality of first transformation matrices. A first transformation matrix having a size greater than or equal to the number of lines, or a second transformation matrix having a size greater than or equal to the number of the plurality of second lines, wherein the plurality of detection patterns are the first transformation matrix. In the case where the first transformation matrix is predetermined based on the transformation matrix and the second transformation matrix and the size of the first transformation matrix is equal to or larger than the number of the plurality of first lines, the first transformation matrix A third transformation matrix excluding a part of the row vector or column vector is used as the first transformation matrix, and the size of the second transformation matrix is larger than the number of the plurality of second lines. If the row vector of the second transformation matrix Alternatively, a fourth transformation matrix excluding a part of a column vector is used as the second transformation matrix, and the capacity calculation unit performs each transposition of the first transformation matrix and the second transformation matrix. Matrixes or their respective generalized inverses may be used.

The above configuration may further include a touch position detection circuit that detects a touch position on the touch panel based on each capacitance calculated by the capacitance calculation circuit.
In the above configuration, the transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines, and the plurality of detection patterns are row vectors of the transformation matrix. Alternatively, excluding a part of the column vector, the number of rows or the number of columns is predetermined based on a matrix in which the number of the first lines or the plurality of second lines is matched, and the capacitance calculation circuit includes It may use a transpose of the matrix or a generalized inverse matrix.

In the above configuration, the capacitance calculation circuit may process the output signal of the capacitance measurement circuit as 0 when the detection pattern is a predetermined detection pattern among the plurality of detection patterns.
In the above configuration, the capacitance calculation circuit may process the output signal of the capacitance measurement circuit as 0 when a predetermined detection pattern and drive pattern among the plurality of detection patterns and drive patterns.

Another aspect of the present invention includes a touch panel including a plurality of first lines and a plurality of second lines arranged so as to intersect the plurality of first lines via an insulating layer. A sensor signal processing circuit having a first drive terminal and a second drive terminal, a detection terminal, and an output terminal, the first drive terminal being connected between the first drive terminal and the detection terminal A capacitance measuring circuit that converts a difference between the first capacitance and the second capacitance connected between the second drive terminal and the detection terminal into a predetermined signal and outputs the predetermined signal; Each time one drive pattern is selected from among a plurality of drive patterns determined according to a certain transformation matrix, one of the plurality of first lines is selected according to the selected drive pattern. Select these lines as the first drive line group. Alternatively, in addition to the first drive line group, zero or more lines different from the first drive line group are selected as the second drive line group, and the first drive line group is selected as the first drive line group. Connecting to the terminal, connecting the second drive line group to the second drive terminal, and selecting one or more lines as a detection line group from the plurality of second lines, A selection circuit that connects a detection line group to the detection terminal, each predetermined signal detected by the capacitance measurement circuit, and the conversion matrix are used to perform an operation, and the selected drive line and each selected detection A signal processing circuit for a touch sensor, comprising: a capacitance calculation circuit that calculates a capacitance at each intersection with the line.

In the above configuration, the transformation matrix may be a Hadamard transformation matrix.
Further, the Hadamard transform matrix is composed of n rows × n columns (n = 2, a multiple of 4), the plurality of detection patterns are n drive patterns, and the selected first and second drive lines are selected. The total number of lines belonging to the group may be n.
The above configuration may further include a touch position detection circuit that detects a touch position on the touch panel based on each capacitance calculated by the capacitance calculation circuit.

In the above configuration, the transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines, and the plurality of detection patterns are row vectors of the transformation matrix. Alternatively, excluding a part of the column vector, the number of rows or the number of columns is predetermined based on a matrix in which the number of the first lines or the plurality of second lines is matched, and the capacitance calculation circuit includes It may use a transpose of the matrix or a generalized inverse matrix.

In the above configuration, the capacitance calculation circuit may process the output signal of the capacitance measurement circuit as 0 when the drive pattern is a predetermined drive pattern among the plurality of drive patterns.
Another aspect of the present invention is a touch sensor comprising the touch sensor signal processing circuit according to any one of the above aspects.

According to another aspect of the present invention, there is provided a touch panel including a plurality of first lines and a plurality of second lines arranged so as to intersect the plurality of first lines via an insulating layer, and outputs a driving voltage. A driving circuit having a first output terminal and a second output terminal, a first voltage corresponding to the input voltage of the first input terminal, and a second voltage corresponding to the input voltage of the second input terminal; A voltage detection circuit that detects a differential voltage of the first circuit, a selective connection between the plurality of first lines and a first output terminal or a second output terminal of the drive circuit, and the plurality of second lines. A signal processing method of a touch sensor, including a selection circuit that performs selective connection between a line and a first input terminal or a second input terminal of the voltage detection circuit, wherein the computer determines in advance Multiple patterns defined according to a certain transformation matrix One pattern is selected, and one or more lines are selected as a first drive line group from the plurality of first lines according to the selected pattern, or the first drive is selected. In addition to the line group, zero or more lines different from the first drive line group are selected as the second drive line group, and the first drive line group is connected to the first output terminal of the drive circuit. The first step of controlling the operation of the selection circuit so as to connect the second drive line group to the second output terminal of the drive circuit, and among the plurality of second lines, 1 One or more lines are selected as a first detection line group, zero or more lines different from the first detection line group are selected as a second detection line group, and the first detection line group is selected as the first detection line group. Connect to the first input terminal of the voltage detection circuit A second step of controlling the operation of the selection circuit so as to connect the second detection line group to a second input terminal of the voltage detection circuit; and the drive circuit outputting a predetermined drive voltage. Based on the third step of controlling the operation of the drive circuit and controlling the operation of the voltage detection circuit so that the voltage detection circuit detects the differential voltage, the output signal of the voltage detection circuit, and the conversion matrix. And a fourth step of calculating a capacitance at each intersection of the selected drive line and each selected detection line, respectively, and performing signal processing of the touch sensor Is the method.

In the above-described configuration, in the first step, the plurality of first lines and the plurality of second lines are divided into the first drive line group and the second drive line group for each of the plurality of patterns. In the second step, the plurality of first lines and the plurality of second lines are changed to the first detection line group and the second step in response to the change in the first step. The selection as the second detection line group may be changed.

In the above configuration, when the predetermined pattern is the plurality of patterns, in the first step, the voltage detection is performed by connecting the selected first drive line group to the first output terminal of the drive circuit. The connection is changed to the connection to the first input terminal of the circuit, and the connection of the selected second drive line group to the second output terminal of the drive circuit is connected to the second input terminal of the voltage detection circuit. In the second step, the connection of the selected first detection line group to the first input terminal of the voltage detection circuit is changed to the connection to the first output terminal of the drive circuit, The connection of the selected second detection line group to the second input terminal of the voltage detection circuit may be changed to the connection to the second output terminal of the drive circuit.

Further, when the pattern is a predetermined pattern among the plurality of patterns, the processes from the first step to the third step are omitted, and the output signal of the voltage detection circuit is processed as 0 in the fourth step. It may be.
In the above configuration, the transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines, and the plurality of patterns include a row vector of the transformation matrix or Excluding a part of the column vector, the number of rows or the number of columns is determined in advance based on a matrix in which the number of the plurality of first lines or the plurality of second lines is matched, and the first step and the second step In each process of the step, the plurality of predetermined detection patterns may be used, and in the process of the fourth step, a transposed matrix or a generalized inverse matrix of the matrix may be used.

In the above configuration, the transformation matrix uses a first transformation matrix and a second transformation matrix, and any one of the first transformation matrix and the second transformation matrix is the plurality of first transformation matrices. A first transformation matrix having a size greater than or equal to the number of lines, or a second transformation matrix having a size greater than or equal to the number of the plurality of second lines, wherein the plurality of patterns are the first transformation matrix. In the case where the first transformation matrix is predetermined based on the matrix and the second transformation matrix and the size of the first transformation matrix is equal to or larger than the number of the plurality of first lines, When a third transformation matrix excluding a part of a row vector or column vector is used as the first transformation matrix, and the size of the second transformation matrix is larger than the number of the plurality of second lines. Includes a row vector of the second transformation matrix or A fourth transformation matrix excluding a part of the column vector is used as the second transformation matrix in advance, and in each process of the first step and the second step, the first transformation matrix and the second transformation matrix A plurality of patterns defined by a transformation matrix are used, and the transposition matrix of each of the first transformation matrix and the second transformation matrix or their respective generalized inverse matrix is used in the processing of the fourth step. It's okay.

In the above configuration, the transformation matrix may be a Hadamard transformation matrix.
Another aspect of the present invention is a touch sensor signal processing program that causes a computer to execute each step in the touch sensor signal processing method described in the above aspect.

According to the present invention, there is provided a signal processing circuit for a touch sensor that employs a new signal processing for the signal processing of the touch sensor.
Further, according to the present invention, regarding signal processing of the touch panel, noise generated when a finger touches the touch panel can be reduced, and S / N can be improved.

It is a block diagram which shows the structure of the touch sensor to which 1st Embodiment of this invention is applied. It is a circuit diagram which shows the specific structure of the selection circuit of 1st Embodiment. It is a circuit diagram which shows the specific structure of the drive part of 1st Embodiment. It is a circuit diagram which shows the specific structure of the voltage detection circuit of 1st Embodiment. It is a figure which shows the timing of the operation | movement of the

states

1 and 2 of a drive circuit and a voltage detection circuit, and the ON / OFF state of the switch at that time. FIG. 5 is a diagram illustrating the timing of operations in states 1 to 4 of the drive circuit and the voltage detection circuit, and the on / off states of the switches at that time. FIG. 6 is a diagram summarizing the relationship between the operation of states 1 to 4 of the drive circuit and the voltage detection circuit and the on / off states of the corresponding switches. It is explanatory drawing explaining operation | movement of the drive circuit and voltage detection circuit of 1st Embodiment. FIG. 4 is a diagram showing detection patterns 1 to 4 according to the first embodiment and the connection relationship between the corresponding drive circuit and voltage detection circuit and each line. FIG. 6 is a diagram illustrating detection patterns 5 to 8 according to the first embodiment and a connection relationship between the corresponding drive circuit and voltage detection circuit and each line. It is a block diagram which shows the structure of the touch sensor to which 2nd Embodiment of this invention is applied. It is a circuit diagram which shows the specific structure of the electrostatic capacitance circuit of 2nd Embodiment. FIG. 10 is a diagram showing detection patterns 1 to 4 according to the second embodiment and the connection relationship between the corresponding drive circuit and voltage detection circuit and each line. FIG. 10 is a diagram illustrating detection patterns 5 to 8 according to the second embodiment and a connection relationship between the corresponding drive circuit and voltage detection circuit and each line. It is a figure explaining the modification of 2nd Embodiment. It is a block diagram which shows the structure of the touch sensor to which 3rd Embodiment of this invention is applied. It is a circuit diagram which shows the specific structure of the electrostatic capacitance circuit of 3rd Embodiment. FIG. 10 is a diagram showing drive patterns 1 to 4 according to the third embodiment and the connection relationship between the corresponding drive circuit and voltage detection circuit and each line. FIG. 10 is a diagram illustrating drive patterns 5 to 8 according to the third embodiment and the connection relationship between the corresponding drive circuit and voltage detection circuit and each line. It is a block diagram which shows the structure of the touch sensor to which 4th Embodiment of this invention is applied. It is a figure which shows the connection relationship of four lines among the eight conversion patterns of the 1st of 4th Embodiment, the drive circuit corresponding to it, and a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 1st 8 conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and the connection relation of each line. It is a figure which shows the connection relationship of four lines among the eight conversion patterns of the 2nd of 4th Embodiment, the drive circuit corresponding to it, and a voltage detection circuit, and each line. It is a figure which shows remaining 4 of the 2nd 8 conversion patterns of 4th Embodiment, and the connection relationship of the drive circuit and voltage detection circuit corresponding to it, and each line. It is a figure which shows the connection relationship of four lines among the eight 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 3rd 8 conversion patterns of 4th Embodiment, the drive circuit corresponding to it, and the connection relationship of a voltage detection circuit and each line. It is a figure which shows the connection relationship of four lines among the four 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 4th 8 conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and the connection relationship of each line. It is a figure which shows the connection relationship of four lines among the eight 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 5th 8 conversion patterns of 4th Embodiment, the drive circuit corresponding to it, and the connection relationship of a voltage detection circuit and each line. It is a figure which shows the connection relationship of four lines among the eight 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, and a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 6th 8 conversion patterns of 4th Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and the connection relation of each line. It is a figure which shows the connection relation of four lines among the eight 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, and a voltage detection circuit, and each line. It is a figure which shows remaining 4 of the 8th conversion patterns of the 7th of 4th Embodiment, and the connection relationship of a drive circuit and voltage detection circuit corresponding to it, and each line. It is a figure which shows the connection relation of four lines among the eight 8th conversion patterns of 4th Embodiment, the drive circuit corresponding to it, and a voltage detection circuit, and each line. It is a figure which shows the remaining 4 of the 8 8th conversion patterns of 4th Embodiment, and the connection relationship of the drive circuit and voltage detection circuit corresponding to it, and each line. It is a figure which shows the connection relationship of four among the eight conversion patterns of the modification 1 of 4th Embodiment, and the drive circuit and voltage detection circuit corresponding to it. It is a figure which shows the remaining 4 of the 8 conversion patterns of the modification 1 of 4th Embodiment, and the connection relationship of a drive circuit and voltage detection circuit corresponding to it, and each line. It is a flowchart which shows an example of the process sequence of the control by the computer of 5th Embodiment of this invention, and a calculation.

Embodiments of the present invention will be described below with reference to the drawings.
(Configuration of the first embodiment)
FIG. 1 is a block diagram showing a configuration of a touch sensor to which the first embodiment of the present invention is applied.
As shown in FIG. 1, the touch sensor to which the first embodiment is applied includes a touch panel 1, a selection circuit 2, a drive circuit 3, a voltage detection circuit 4, an A / D conversion circuit 5, and a capacitance calculation circuit. 6, a touch position detection circuit 7, a control circuit 8, an address generation circuit 9, a memory 10, and a latch 11.

The touch panel 1 is formed of a substrate (not shown) made of glass or the like, and, for example, eight X lines X1 to X8 are arranged on the substrate at predetermined intervals in the X direction. On the substrate, for example, eight Y lines Y1 to Y8 are arranged at predetermined intervals in the Y direction so as to intersect the X lines X1 to X8 via an insulating layer. For this reason, the X lines X1 to X8 and the Y lines Y1 to Y8 are insulated from each other via an insulating layer and capacitively coupled.

The selection circuit 2 selects, for example, two of the Y lines Y1 to Y8 of the touch panel 1 as drive lines, and connects the selected two drive lines to the drive circuit 3. The selection circuit 2 selects at least two of the X lines X1 to X8 of the touch panel 1 as detection lines, connects a part thereof to one input terminal (detection terminal) of the voltage detection circuit 4, and The rest is connected to the other input terminal (detection terminal) of the voltage detection circuit 4.

The drive circuit 3 generates a voltage whose voltage value (amplitude) changes as will be described later, and supplies the generated voltage as a drive voltage to the two lines selected as the drive lines by the selection circuit 2.
In the voltage detection circuit 4, when the selection circuit 2 selects at least two of the X lines X1 to X8 as detection lines, and the selected detection lines are connected to the two input terminals, the voltage detection circuit 4 corresponds to the connection. The voltage is output as the output voltage.

The A / D conversion circuit 5 A / D converts the output voltage of the voltage detection circuit 4 and outputs the A / D converted voltage to the capacitance calculation circuit 6.
As will be described later, the capacity calculation circuit 6 performs an operation based on each output voltage of the voltage detection circuit 4 A / D converted by the A / D conversion circuit 5 and a predetermined conversion matrix. The capacitance at each intersection of one drive line selected by the selection circuit 2 and each detection line selected by the selection circuit 2, the other drive line selected by the selection circuit 2, and the selection circuit 2 The capacitances of the differences from the capacitances at the intersections with the respective detection lines selected in (1) are calculated.

The touch position detection circuit 7 detects the touch position of the touch panel 1 based on each capacitance calculated by the capacitance calculation circuit 6.
When detecting the touch position of the touch panel 1, the control circuit 8 controls the driving circuit 3, the voltage detection circuit 4, the address generation circuit 9, and the latch 11 as described later.
The address generation circuit 9 generates an address for reading setting data for controlling the operation of the selection circuit 2 stored in the memory 10 based on an instruction from the control circuit 8.
In the memory 10, when detecting the touch position of the touch panel 1, data for controlling on / off of a switch described later of the selection circuit 2 according to the detection procedure is stored in advance.
The latch 11 temporarily stores setting data read from the memory 10 when on / off control of a later-described switch of the selection circuit 2 is performed.

Next, a specific configuration of the selection circuit 2 in FIG. 1 will be described with reference to FIG.
The selection circuit 2 includes switch units 21-1 to 21-8, switch units 22-1 to 22-8, decoders 23-1 to 23-8, decoders 24-1 to 24-8, and a connection line 25. To 29. However, in FIG. 2, the switch units 21-5 to 21-8, the switch units 22-5 to 22-8, the decoders 23-5 to 23-8, and the decoders 24-5 to 24-8 are omitted.

The switch units 21-1 to 21-8 connect the X lines X1 to X8 to any one of the voltage detection circuit 4, the drive circuit 3, and the ground voltage VSS via the connection lines 25 to 29. It is. The switch units 22-1 to 22-8 connect the Y lines Y1 to Y8 to any one of the voltage detection circuit 4, the drive circuit 3, and the ground voltage VSS via the connection lines 25 to 29. It is.

Therefore, each of the switch units 21-1 to 21-8 and the switch units 22-1 to 22-8 includes five switches SW11 to SW15. However, in FIG. 2, only the switches SW11 to SW15 of the switch unit 22-4 are denoted by reference numerals, and those numerals are omitted for the other switch sections.
The switch SW11 is used to connect the input terminal 44 of the voltage detection circuit 4 to one of the X lines X1 to X8 and the Y lines Y1 to Y8. The switch SW12 is used to connect the input terminal 45 of the voltage detection circuit 4 to one of the X lines X1 to X8 and the Y lines Y1 to Y8.

The switch SW13 is used to connect the output terminal 33 of the drive circuit 3 to one of the X lines X1 to X8 and the Y lines Y1 to Y8. The switch SW14 is used to connect the output terminal 34 of the drive circuit 3 to one of the X lines X1 to X8 and the Y lines Y1 to Y8. The switch SW15 is used to connect one of the X lines X1 to X8 and the Y lines Y1 to Y8 to the ground voltage VSS.

The decoders 23-1 to 23-8 perform on / off control of the switches SW11 to SW15 included in each of the switch units 21-1 to 21-8 according to the output data from the latch 11. The decoders 24-1 to 24-8 perform on / off control of the switches SW11 to SW15 included in each of the switch units 22-1 to 22-8 according to the output data from the latch 11.

Next, a specific configuration of the drive circuit 3 in FIG. 1 will be described with reference to FIG.
As illustrated in FIG. 3, the drive circuit 3 includes a first drive circuit 31, a second drive circuit 32, and two

output terminals

33 and 34.
The first drive circuit 31 connects the switch SW1 and the switch SW2 in series, applies a high-potential power supply voltage VDD (for example, 3.3V) to one end of the switch SW1, and applies a low-potential power supply voltage to one end of the switch SW2. A certain ground voltage VSS (for example, 0 V) is applied. Then, the power supply voltage VDD and the power supply voltage VSS are selectively output from the output terminal 33 by performing on / off control of the switches SW1 and SW2.

The second drive circuit 32 connects the switch SW3 and the switch SW4 in series, applies the power supply voltage VDD to one end of the switch SW3, and applies the power supply voltage VSS to one end of the switch SW4. Then, the power supply voltage VDD and the power supply voltage VSS are selectively output from the output terminal 34 by performing on / off control of the switches SW3 and SW4.

Next, a specific configuration of the voltage detection circuit 4 of FIG. 1 will be described with reference to FIG.
As shown in FIG. 4, the voltage detection circuit 4 includes an integration circuit 41 that integrates an input voltage described later, an integration circuit 42 that integrates an input voltage described later, an output voltage of the integration circuit 41, and an output voltage of the integration circuit 42. And a subtracting circuit 43 for calculating the difference between the two and two

input terminals

44 and 45.
As shown in FIG. 4, the integration circuit 41 includes an operational amplifier OP1, an integration capacitor Cf, and a switch SW6.

The input voltage is input to the inverting input terminal (−) of the operational amplifier OP1, and the voltage VCOM (VDD / 2) is applied to the non-inverting input terminal (+) of the operational amplifier OP1. Further, a parallel circuit of an integrating capacitor Cf and a switch SW6 is connected between the inverting input terminal and the output terminal of the operational amplifier OP1.
As shown in FIG. 4, the integration circuit 42 includes an operational amplifier OP2, an integration capacitor Cf, and a switch SW5.

The input voltage is input to the inverting input terminal of the operational amplifier OP2, and the voltage VCOM (VDD / 2) is applied to the non-inverting input terminal of the operational amplifier OP2. Further, a parallel circuit of an integrating capacitor Cf and a switch SW5 is connected between the inverting input terminal and the output terminal of the operational amplifier OP2.
As shown in FIG. 4, the subtraction circuit 43 includes an operational amplifier OP3 and four resistors R1 to R4.

The output of the integrating circuit 42 is supplied to the inverting input terminal of the operational amplifier OP3 via the resistor R2, and the output of the integrating circuit 41 is supplied to the non-inverting input terminal of the operational amplifier OP3 via the resistor R1. The non-inverting input terminal of the operational amplifier OP3 is connected to the voltage VCOM (VDD / 2) through the resistor R3. A resistor R4 is connected as a feedback resistor between the inverting input terminal and the output terminal of the operational amplifier OP3.

Next, operations of the drive circuit 3 and the voltage detection circuit 4 will be described with reference to FIGS. The drive circuit 3 and the voltage detection circuit 4 constitute a capacitance measurement circuit.
As shown in FIG. 5, the driving circuit 3 and the voltage detection circuit 4 repeat the operation of the “state 1” operation (charging operation) and the “state 2” operation (charge-voltage conversion operation) as one operation. .
In “state 1”, the switches SW1 and SW4 of the drive circuit 3 are turned on, SW2 and SW3 are turned off, and the switches SW5 and SW6 of the voltage detection circuit 4 are turned on. In “state 2”, the switches SW1 and SW4 of the drive circuit 3 are turned off, SW2 and SW3 are turned on, and the switches SW5 and SW6 of the voltage detection circuit 4 are turned off.

Further, as shown in FIG. 6, the drive circuit 3 and the voltage detection circuit 4 may perform the operations of “state 1” to “state 4” as one operation and repeat this operation.
In the case of FIG. 6, in “State 1” and “State 2”, the switches SW1 to SW6 are turned on / off in the same manner as the first operation. In “state 3”, the switches SW1 and SW4 of the drive circuit 3 are turned off, SW2 and SW3 are turned on, and the switches SW5 and SW6 of the voltage detection circuit 4 are turned on. In “state 4”, the switches SW1 and SW4 of the drive circuit 3 are turned on, SW2 and SW3 are turned off, and the switches SW5 and SW6 of the voltage detection circuit 4 are turned off.

FIG. 7 shows a summary of the operations of “state 1” to “state 4” and the on / off states of the switches SW1 to SW6 corresponding thereto.
In the case of the operation shown in FIG. 6, in the

states

1, 2, and 3, 4, the drive circuit 3 can apply voltages having different polarities to the same drive line, and the voltage detection circuit 4 performs two measurements. Can be performed (see FIG. 8). By taking the difference between the two measurements, there is an effect of removing low frequency noise.

(Operation of the first embodiment)
Next, the operation of the first embodiment will be described with reference to the drawings.
First, operations of the drive circuit 3 and the voltage detection circuit 4 will be described with reference to FIG.
FIG. 8 shows a case where the Y lines Y1 and Y2 of the touch panel 1 are connected to the drive circuit 3, and the X lines X1 and X2 of the touch panel 1 are connected to the voltage detection circuit 4, and the X lines X1 and X2 and the Y line Y1 are connected. , Y2 are capacitances formed at the intersections of Y2 and C2.
Then, the drive circuit 3 and the voltage detection circuit 4 perform “state 1” and “state 2” operations as shown in FIG.

In the operation of “state 1”, the switches SW1 and SW4 of the drive circuit 3 are turned on, SW2 and SW3 are turned off, the switches SW5 and SW6 of the voltage detection circuit 4 are turned on, and the on / off states of the switches SW1 to SW6 are shown in FIG. As shown.
For this reason, the drive circuit 3 applies a high-potential power supply voltage VDD (for example, 3.3 V) to the Y line Y2, and applies a low-potential power supply voltage VSS (for example, 0 V) to the Y line Y1. When the switches SW5 and SW6 are turned on, the operational amplifiers OP1 and OP2 become voltage followers, and the X lines X1 and X2 are driven to the voltage VCOM. Thereby, the electrostatic capacitances C1 and C2 are charged and the electrostatic capacitances C3 and C4 are charged.

Thereafter, in the operation of “state 2”, the switches SW1 and SW4 of the drive circuit 3 are turned off, SW2 and SW3 are turned on, and the switches SW5 and SW6 of the voltage detection circuit 4 are turned off. Therefore, some of the charges charged in the capacitances C1, C2, C3, and C4 move to the integration capacitor Cf of the

integration circuits

41 and 42, and the output terminal of the operational amplifier OP1 has the following equation (1A). An output voltage Vout1 like this appears, and an output voltage Vout2 like the following expression (1B) appears at the output terminal of the operational amplifier OP2.
Vout1 = VCOM + {(C1-C2) / Cf} × VDD
... (1A)
Vout2 = VCOM + {(C3-C4) / Cf} × VDD
... (1B)

In the operational amplifier OP3, an operation for obtaining a difference between the output voltage of the operational amplifier OP1 and the output voltage of the operational amplifier OP2 is performed. As a result, the output voltage Vout of the voltage detection circuit 4 is expressed by the following equation (1C).
Vout = VCOM + {(C1-C2-C3 + C4) / Cf} × VDD
... (1C)
As shown in FIG. 5, the output voltage Vout of the voltage detection circuit 4 is A / D converted at a predetermined timing within the period of “state 2”.

Next, in the first embodiment, an operation when detecting the touch position of the touch panel 1 will be described with reference to FIGS.
First, the selection circuit 2 selects two predetermined lines as drive lines among the Y lines Y1 to Y8 of the touch panel 1 in accordance with a predetermined drive pattern. In this example, Y lines Y 1 and Y 2 are selected as drive lines, and the selected Y lines Y 1 and Y 2 are connected to the drive circuit 3.

In addition, when one of eight predetermined detection patterns is selected according to a predetermined conversion matrix, the selection circuit 2 selects the X lines X1 to X1 of the touch panel 1 according to the selected detection pattern. A part of X8 is connected to one input terminal of the voltage detection circuit 4, and the remainder of the X lines X1 to X8 is connected to the other input terminal of the voltage detection circuit 4.

FIGS. 9A to 9D and FIGS. 10E to 10H show eight detection patterns 1 to 8 determined according to the Hadamard transform matrix and X lines X1 to X8 corresponding to these detection patterns. And the voltage detection circuit 4 are connected.
For example, in the case of detection pattern 1 shown in FIG. 9A, X lines X1 to X8 are connected to one input terminal of voltage detection circuit 4, and the other input terminal of voltage detection circuit 4 is connected to VCOM. The In the case of the detection pattern 2 shown in FIG. 9B, the X lines X1, X3, X5, and X7 are connected to one input terminal of the voltage detection circuit 4, and the X lines X2, X4, X6, and X8 are connected. The other input terminal of the voltage detection circuit 4 is connected.

9 and 10, reference numerals C1 to C8 are capacitances formed at the intersections of the Y line Y2 and the X lines X1 to X8. Reference numerals C9 to C16 are Y line Y1 and Capacitance formed at each intersection with the X lines X1 to X8.
In the case of the detection pattern 1 shown in FIG. 9A, the output voltage D1 of the voltage detection circuit 4 is as follows.
D1 = VCOM + {(C1 + C2 + C3 + C4 + C5 + C6 + C7 + C8-C9
-C10-C11-C12-C13-C14-C15-C16) / Cf} × VDD
The output voltage Dn based on the detection patterns shown in FIGS. 9 and 10 can be expressed by the following equation (1D).

Also, the signs “+” and “−” in FIGS. 9 and 10 mean that “+” is sk = + 1 and “−” is sk = −1.
Next, for each of the detection patterns 1 to 8, the drive circuit 3 and the voltage detection circuit 4 perform the operations of “state 1” and “state 2” shown in FIG. A corresponding potential difference is detected, and this detected voltage is output as an output voltage.
The calculation process in which the voltage detection circuit 4 detects the eight potential differences according to the detection patterns 1 to 8 can be expressed by the following equation (2). Note that VCOM and VDD / Cf in the expression (1D) are not related to capacitance calculation and touch coordinate detection, and are omitted for simplification.

In the equation (2), D1 to D8 are output voltages (detection voltages) of the voltage detection circuit 4 obtained according to the eight detection patterns 1 to 8. The transformation matrix on the right side is a Hadamard transformation matrix. C1 to C8 are capacitances between the Y line Y2 and the X lines X1 to X8. C9 to C16 are capacitances between the Y line Y1 and the X lines X1 to X8.
Each of the eight rows of the Hadamard transform matrix corresponds to the eight detection patterns 1 to 8 described above. Further, 1 and −1 in each row correspond to the connection state between the X lines X1 to X8 of each detection pattern and the voltage detection circuit 4.

The output voltages D1 to D8 of the voltage detection circuit 4 are each A / D converted by the A / D conversion circuit 5 at a predetermined timing of the operation of “state 2” in FIG. The A / D converted output voltages D1 to D8 are sequentially stored in the capacitance calculation circuit 6. When the storage of the output voltages D1 to D8 is completed, the capacitance calculation circuit 6 performs the capacitance difference (C1-C9), (C2) based on the stored output voltages D1 to D8 and the Hadamard transformation matrix that is the transformation matrix. -C10)... (C8-C16) are calculated.
The arithmetic processing performed by the capacity calculation circuit 6 can be expressed by the following equation (3).

The touch position detection circuit 7 detects the position of the touch panel 1 based on the capacitance values (C1-C9), (C2-C10)... (C8-C16) calculated by the capacitance calculation circuit 6.
The above operation is an example in which the touch position on the touch panel 1 is detected by a one-dimensional operation. However, when the touch position on the touch panel 1 is detected by a two-dimensional operation, the above operation is repeated. become.
In this case, the selection circuit 2 sequentially changes the connection between the Y lines Y1 to Y8 and the drive circuit 3 according to the drive pattern, and for each change, the voltage detection circuit 4 changes to the detection patterns 1 to 8 described above. In response, a calculation process for detecting eight voltages is performed.

Next, specific examples of selection and connection operations of the selection circuit 2 will be described with reference to FIGS.
In the first embodiment, data relating to the selection and connection operations of the selection circuit 2 is stored in advance in the memory 10 for each predetermined drive pattern and detection pattern. That is, the memory 10 stores the switch SW11 of each of the switch units 21-1 to 21-8 and the switch units 22-1 to 22-8 of the selection circuit 2 for each predetermined drive pattern and detection pattern 1 to 8. Stores data for ON / OFF control of SW15.

Then, the control circuit 8 instructs the address generation circuit 9 to generate an address for reading out the data for each of the predetermined drive patterns and detection patterns 1 to 8, and latches necessary data according to the generated address. Read to.
The data read to the latch 11 is transferred to the decoders 23-1 to 23-8 and the decoders 24-1 to 24-8. Thus, the decoders 23-1 to 23-8 perform on / off control of the switches SW11 to SW15 of the switch units 21-1 to 21-8. Further, the decoders 24-1 to 24-8 perform on / off control of the switches SW11 to SW15 of the switch units 22-1 to 22-8.

For example, when the Y lines Y1 and Y2 are selected as drive lines according to the drive pattern, and the selected Y lines Y1 and Y2 are connected to the drive circuit 3, the decoder 24-1 is connected to the switch section 22-1. The switch SW13 is turned on, and the decoder 24-2 turns on the switch SW14 of the switch unit 22-2.

Further, according to the detection pattern, among the X lines X1 to X8 of the touch panel 1, X lines X1 to X4 are selected as the first detection lines, and X lines X5 to X8 are selected as the second detection lines, respectively. When the X lines X1 to X4 and the X lines X5 to X8 are connected to the voltage detection circuit 4, respectively, the operation is as follows.
That is, each of the decoders 23-1 to 23-4 turns on the switch SW11 of the switch units 21-1 to 21-4. Each of the decoders 23-5 to 23-8 turns on the switch SW12 of the switch units 21-5 to 21-8.

As described above, in the first embodiment, the voltage detection circuit 4 performs the calculation process according to the first to eighth detection patterns to obtain the output voltages D1 to D8, respectively, and the output voltages D1 to D8 are obtained. Differential amplification was performed when D8 was obtained. Therefore, noise can be reduced when the output voltages D1 to D8 are obtained, and the S / N can be improved.

In the first embodiment, since the voltage detection circuit 4 uses the capacitance formed between the lines of the touch panel 1 as a capacitor for offset adjustment in order to obtain the output voltages D1 to D8. There is no need to provide a capacitor.
In the first embodiment, an Hadamard transformation matrix of 8 rows × 8 columns is used as shown in the equation (2). However, a Hadamard transform matrix such as 4 rows × 4 columns or 16 rows × 16 columns can also be used.

Therefore, when the Hadamard transformation matrix of n rows × n columns (n = 2, a multiple of 4) is used, the number of the detection patterns is n, and the voltage detection circuit 4 is used according to each detection pattern. There are n detection lines. In the above example, there are eight detection patterns as shown in FIGS. 9 and 10, and eight detection lines are used in the voltage detection circuit 4 in accordance with the eight detection patterns.

(Modification 1 of the first embodiment)
Modification 1 is a case where the number of lines (number of electrodes) of the touch panel is not a multiple of 4, for example, 7 in the X-axis direction.
In the first modification, the basic configuration is the same as that in FIG. 1, and only the size of the touch panel 1 is different. The operation is also the same as in the first embodiment. Only the parts different from the first embodiment will be described below.

The size of the Hadamard transform matrix is selected by a multiple of 4 that is greater than the number of electrodes. Here, since the number of electrodes in the X-axis direction is 7, 8 is used as a minimum multiple of 4 that is 7 or more, that is, an Hadamard transformation matrix of 8 rows × 8 columns is used.
The detection pattern uses eight types of detection patterns according to the Hadamard transform matrix of the selected size. That is, the electrode X8 in FIGS. 9 and 10 is omitted.
The calculation process in which the voltage detection circuit 4 detects the eight potential differences according to the eight detection patterns described above can be expressed by the following equation (4).

The coefficient matrix of equation (4) deletes the eighth column (rightmost column) of the 8-row × 8-column Hadamard transformation matrix that is the coefficient matrix of equation (2), and sets the number of columns to an electrode in the X-axis direction. It matches the number. Note that the position of the column to be deleted may be anywhere, and the number of columns as a result of deleting the column only needs to match the number of electrodes in the X-axis direction.
The eight output voltages output from the voltage detection circuit 4 are each A / D converted by the A / D conversion circuit 5 in a predetermined evening of the operation of “state 2” in FIG. The A / D converted output voltages are sequentially stored in the capacity calculation circuit 6. When the storage of the output voltages D1 to D8 is completed, the capacitance calculation circuit 6 performs the capacitance difference (C1-C9), (C2) based on the stored output voltages D1 to D8 and the Hadamard transformation matrix that is the transformation matrix. -C10)... (C7-C15) are calculated.
The arithmetic processing performed by the capacity calculation circuit 6 can be expressed by the following equation (5).

However, the coefficient matrix appearing in the equation (5) has a transposed matrix of the coefficient matrix of the equation (4) and a Moore-Penrose generalized inverse matrix (a scalar multiple thereof).
Although the output voltage output from the voltage detection circuit 4 is eight and more than seven electrodes, the coefficient matrix of the equation (5) is obtained because it is a generalized inverse matrix of the coefficient matrix of the equation (4). (C1-C9), (C2-C10)... (C7-C15) are least squares solutions that satisfy the equation (4). Therefore, the greater the number of output voltages of the voltage detection circuit 4, the better the S / N.
In the first modified example, the coefficient matrix appearing in the equation (4) is not the one obtained by deleting some columns of the Hadamard transform, but the coefficient matrix obtained by deleting some columns of the orthogonal matrix and the orthogonal matrix multiplied by the scalar. Applicable.
Note that the first modification can be applied to second and third embodiments described later.

(Modification 2 of the first embodiment)
In the first embodiment, as shown in FIGS. 9 and 10A to 10H, Y1 is connected to the-terminal 34 of the drive circuit 3, Y2 is connected to the + terminal 33 of the drive circuit 3, and X1 to X8 are The drive circuit 3 and the voltage detection circuit 4 can be exchanged, although they are configured to be connected to the + side terminal 44 or the − side terminal 45 of the voltage detection circuit 4 according to a predetermined pattern. That is, Y1 is connected to the negative terminal 45 of the voltage detection circuit 4, Y2 is connected to the positive terminal of the voltage detection circuit 4, and X1 to X8 are the positive side terminal 33 or negative side terminal 34 of the drive circuit 3 according to a predetermined pattern. It can also be configured to connect to. Even in this configuration, the output of the voltage detection circuit is exactly the same as in the first embodiment, and therefore, the same configuration as in FIG. 1 can be used only by changing the drive / detection pattern stored in the memory 10 of FIG. it can. In this case, since all patterns including the pattern of FIG. 9A are detected with a differential configuration, resistance to common mode noise is improved.
The second modification can be applied to the first modification of the first embodiment.

(Configuration of Second Embodiment)
FIG. 11 is a block diagram showing a schematic configuration of a touch sensor to which the second embodiment of the present invention is applied.
As shown in FIG. 11, the touch sensor to which the second embodiment is applied includes a touch panel 1, a selection circuit 2, a drive circuit 3, a voltage detection circuit 4, an A / D conversion circuit 5, and a capacitance calculation circuit. 6A, a touch position detection circuit 7A, a control circuit 8A, an address generation circuit 9, a memory 10, a latch 11, and a capacitance circuit 12 for offset adjustment.

As described above, the second embodiment is based on the configuration of the first embodiment shown in FIG. 1, and the capacitance calculation circuit 6, the touch position detection circuit 7, and the control circuit 8 shown in FIG. The capacitance calculation circuit 6A, the touch position detection circuit 7A, and the control circuit 8A are replaced with a capacitance circuit 12.

Here, the second embodiment has parts common to the components of the first embodiment. The common components are denoted by the same reference numerals, and the description thereof is omitted as much as possible.
As shown in FIG. 12, the capacitance circuit 12 includes offset adjusting capacitors CR1 and CR2 each having a predetermined capacitance value, and switches SW7 to SW9.

One end of the capacitor CR1 is connected to the input terminal 44 of the voltage detection circuit 4, and the other end of the capacitor CR1 is connected to the output terminal 34 of the drive circuit 3 via the switch SW7. One end side of the capacitor CR2 is connected to the input terminal 45 of the voltage detection circuit 4, and the other end side of the capacitor CR2 is connected to the output terminal 34 of the drive circuit 3 via the switch SW8. Furthermore, one end side of the switch SW9 is connected to the input terminal 45 of the voltage detection circuit 4, and the other end side of the switch SW9 is connected to VCOM.
When detecting the touch position of the touch panel 1, the control circuit 8A controls the drive circuit 3, the voltage detection circuit 4, the address generation circuit 9, the latch 11, and the capacitance circuit 12 as described later.

(Operation of Second Embodiment)
Next, a case where the touch position of the touch panel 1 is detected in the second embodiment will be described with reference to FIGS.
First, the selection circuit 2 selects one predetermined line from among the Y lines Y1 to Y8 of the touch panel 1 as a drive line according to a predetermined drive pattern. In this example, the Y line Y1 is selected as the drive line, and the selected Y line Y1 is connected to the output terminal 33 of the drive circuit 3 (see FIGS. 13 and 14).

In addition, when one of eight predetermined detection patterns is selected according to a predetermined conversion matrix, the selection circuit 2 selects the X lines X1 to X1 of the touch panel 1 according to the selected detection pattern. A part of X8 is connected to the input terminal 44 of the voltage detection circuit 4, and the remainder of the X lines X1 to X8 is connected to the input terminal 45 of the voltage detection circuit 4.

FIGS. 13A to 13D and FIGS. 14E to 14H show detection patterns 1 to 8 determined according to the Hadamard transformation matrix and X lines X1 to X corresponding to these detection patterns 1 to 8, respectively. The connection state between X8 and the voltage detection circuit 4 is shown.
For example, in the case of the detection pattern 1 shown in FIG. 13A, the X lines X 1 to X 8 are connected to the input terminal 44 of the voltage detection circuit 4. In the case of the second detection pattern shown in FIG. 13B, the X lines X1, X3, X5, and X7 are connected to the input terminal 44 of the voltage detection circuit 4, and the X lines X2, X4, X6, and X8 are connected. Is connected to the input terminal 45 of the voltage detection circuit 4.

Reference numerals C1 to C8 in FIGS. 13 and 14 are capacitances (capacitors) formed between the Y line Y1 and the X lines X1 to X8, respectively.
Next, for each of the detection patterns 1 to 8, the drive circuit 3 and the voltage detection circuit 4 perform the operations of “state 1” and “state 2” shown in FIG. A potential difference corresponding to ˜8 is detected.

As shown in FIGS. 13 and 14, in the case of the detection pattern 1, the switches SW7 and SW9 shown in FIG. 12 are turned on. For this reason, the capacitor CR1 is connected between the output terminal 34 of the drive circuit 3 and the input terminal 44 of the voltage detection circuit 4, and the input terminal 45 of the voltage detection circuit 4 is connected to VCOM.
In the case of detection patterns 2 to 8, the switches SW7 and SW8 shown in FIG. 12 are turned on. Therefore, the capacitor CR1 is connected between the output terminal 34 of the drive circuit 3 and the input terminal 44 of the voltage detection circuit 4, and the capacitor CR2 is connected between the output terminal 34 of the drive circuit 3 and the input terminal 45 of the voltage detection circuit 4. Connected between.
Here, the calculation processing in which the voltage detection circuit 4 detects eight potential differences according to the detection patterns 1 to 8 can be expressed by the following equation (6).

In the equation (6), D1 to D8 are output voltages (detection voltages) of the voltage detection circuit 4 obtained according to the eight detection patterns 1 to 8. The transformation matrix on the right side is a Hadamard transformation matrix. C1 to C8 are capacitances between the Y line Y1 and the X lines X1 to X8.
Here, each of the eight rows of the Hadamard transform matrix corresponds to the eight detection patterns 1 to 8 described above. Further, 1 and −1 in each row correspond to the connection state between the X lines X1 to X8 of each detection pattern and the voltage detection circuit 4.

The output voltages D1 to D8 output from the voltage detection circuit 4 are each A / D converted by the A / D conversion circuit 5 at a predetermined timing of the operation of “state 2” in FIG. The A / D converted output voltages D1 to D8 are sequentially stored in the capacity calculation circuit 6A. When the storage of the output voltages D1 to D8 is completed, the capacity calculation circuit 6A performs an operation for calculating the capacitances C1 to C8 based on the stored output voltages D1 to D8 and the Hadamard transform matrix as a conversion matrix. Do.
The arithmetic processing performed by the capacity calculation circuit 6A can be expressed by the following equation (7).

The touch position detection circuit 7A detects the touch position of the touch panel 1 based on the capacitances C1 to C8 calculated by the capacitance calculation circuit 6A.
The above operation is an example in which the touch position on the touch panel 1 is detected by a one-dimensional operation. However, when the touch position on the touch panel 1 is detected by a two-dimensional operation, the above operation is repeated. become.
In this case, the connection between the Y lines Y1 to Y8 and the drive circuit 3 is sequentially changed according to the drive pattern, and for each change, the voltage detection circuit 4 has eight outputs corresponding to the detection patterns 1 to 8. An arithmetic process for detecting the voltage is performed.

As described above, in the second embodiment, when the voltage detection circuit 4 obtains the output voltages D1 to D8 by performing arithmetic processing according to the eight detection patterns, and obtains the output voltages D1 to D8, respectively. Differential amplification was performed. Therefore, noise can be reduced when the output voltages D1 to D8 are obtained, and the S / N can be improved.
In the second embodiment, an Hadamard transformation matrix of 8 rows × 8 columns is used as shown in Equation (6). However, a Hadamard transform matrix such as 4 rows × 4 columns or 16 rows × 16 columns can also be used.

Therefore, when the Hadamard transformation matrix of n rows × n columns (n = 2, a multiple of 4) is used, the number of the detection patterns is n, and the voltage detection circuit 4 is used according to each detection pattern. There are n detection lines. In the above example, there are eight detection patterns as shown in FIGS. 13 and 14, and eight detection lines are used in the voltage detection circuit 4 in accordance with these eight detection patterns.

(Modification 1 of 2nd Embodiment)
Next, in the second embodiment, a detection example of hovering that specifies the position when the finger is not in contact with the touch panel 1 but approaches the touch panel 1 will be described with reference to FIG.
In this example, hovering detection is performed by combining the detection pattern 5 in FIG. 14E and the detection pattern 7 in FIG.
FIGS. 15A and 15B show detection states in the detection pattern 5. (A) is the case where the finger 100 is in the vicinity of the capacitances C1 to C4, and the output voltage D5 of the voltage detection circuit 4 is D5 <0. (B) is the case where the finger 100 is in the vicinity of the capacitances C5 to C8, and the output voltage D5 of the voltage detection circuit 4 is D5> 0.

FIGS. 15C and 15D both show detection states in the detection pattern 7. (C) is the case where the finger 100 is in the vicinity of the capacitances C3 to C6, and the output voltage D7 of the voltage detection circuit 4 is D7> 0. (D) is the case where the finger 100 is in the vicinity of the capacitances C1 and C2 or the capacitances C7 and C8, and the output voltage D7 of the voltage detection circuit 4 is D7 <0.
Therefore, based on the output voltages D5 and D7 of the voltage detection circuit 4, the position of the finger is the capacitance C1, C2, capacitance C3, C4, capacitance C5, C6, or capacitance C7, C8. It can be determined in which neighborhood.

(Modification 2 of the second embodiment)
When multipoint touch detection is not required, the X and Y coordinates of the touch position can be detected by performing the following operation instead of the operation of the second embodiment. In addition, multipoint touch here means that two or more different points on the touch panel are touched within a predetermined time.
First, the selection circuit 2 selects all of the Y lines Y1 to Y8 of the touch panel 1 according to a predetermined drive pattern instead of selecting one predetermined line as a drive line. The rest is the same as the description of the operation of the second embodiment. Thereby, the X coordinate of the touch position can be detected. Next, the above operation is performed again by exchanging the X line and the Y line. Thereby, the Y coordinate of the touch position can be detected.

(Configuration of Third Embodiment)
FIG. 16 is a block diagram showing a schematic configuration of a touch sensor to which the third embodiment of the present invention is applied.
As shown in FIG. 16, the touch sensor to which the third embodiment is applied includes a touch panel 1, a selection circuit 2, a drive circuit 3, a voltage detection circuit 4A, an A / D conversion circuit 5, and a capacitance calculation circuit. 6A, touch position detection circuit 7A, control circuit 8B, address generation circuit 9, memory 10, latch 11, and capacitance circuit 12A for offset adjustment.
In this way, the third embodiment is based on the configuration of the second embodiment shown in FIG. 11, and the differential amplification type voltage detection circuit 4, the control circuit 8A, and the capacitance circuit 12 of FIG. As shown in FIG. 16, a single type voltage detection circuit 4A, a control circuit 8B, and a capacitance circuit 12A are replaced.

Here, the third embodiment has a part common to the constituent elements of the second embodiment, and the common constituent elements are denoted by the same reference numerals, and the description thereof is omitted as much as possible.
As shown in FIG. 17, the voltage detection circuit 4A includes an operational amplifier OP4, an integration capacitor Cf, and a switch SW10.
An input voltage is input to the inverting input terminal (−) of the operational amplifier OP4, and the non-inverting input terminal (+) of the operational amplifier OP4 is connected to VCOM. Further, a parallel circuit of an integrating capacitor Cf and a switch SW10 is connected between the inverting input terminal and the output terminal of the operational amplifier OP4.

As shown in FIG. 17, the capacitance circuit 12A includes an offset adjustment capacitor CR3 having a predetermined capacitance value and a switch SW20. One end side of the capacitor CR3 is connected to the input terminal of the voltage detection circuit 4A, and the other end side of the capacitor CR3 is connected to the output terminal 34 of the drive circuit 3 via the switch SW20.
When detecting the touch position of the touch panel 1, the control circuit 8B controls the drive circuit 3, the voltage detection circuit 4A, the address generation circuit 9, the latch 11, and the capacitance circuit 12A.

(Operation of Third Embodiment)
Next, in the third embodiment, a case where the touch position of the touch panel 1 is detected will be described with reference to FIGS. 16 to 19.
First, the selection circuit 2 selects one predetermined line as a detection line among the Y lines Y1 to Y8 of the touch panel 1 according to a predetermined detection pattern. In this example, the Y line Y1 is selected as the detection line, and the selected Y line Y1 is connected to the input terminal of the voltage detection circuit 4 (see FIGS. 18 and 19).

In addition, when one of eight predetermined drive patterns is selected according to a predetermined conversion matrix, the selection circuit 2 selects the X lines X1 to X1 of the touch panel 1 according to the selected drive pattern. A part of X8 is connected to the output terminal 33 of the drive circuit 3, and the remainder of the X lines X1 to X8 is connected to the output terminal 34 of the drive circuit 3.

18A to 18D and FIGS. 19E to 19H show driving patterns 1 to 8 determined according to the Hadamard transformation matrix and X lines X1 to X corresponding to these driving patterns 1 to 8, respectively. The connection state between X8 and the drive circuit is shown.
For example, in the case of the drive pattern 1 shown in FIG. 18A, the X lines X 1 to X 8 are connected to the output terminal 33 of the drive circuit 3. In the case of the second drive pattern shown in FIG. 18B, the X lines X1, X3, X5, and X7 are connected to the output terminal 33 of the drive circuit 3, and the X lines X2, X4, X6, and X8 are connected. Connected to the output terminal 34 of the drive circuit 3.

Next, for each of the drive patterns 1 to 8, the drive circuit 3 and the voltage detection circuit 4A perform the first operation and the second operation as operations corresponding to “state 1” and “state 2” shown in FIG. The voltage detection circuit 4A detects a voltage corresponding to the drive patterns 1-8.
In the first operation, the switches SW1 and SW4 of the drive circuit 3 are turned on, SW2 and SW3 are turned off, and the switch SW10 of the voltage detection circuit 4A is turned on. In the second operation, the switches SW1 and SW4 of the drive circuit 3 are turned off, SW2 and SW3 are turned on, and the switch SW10 of the voltage detection circuit 4A is turned off.

As shown in FIGS. 18 and 19, in the case of the drive pattern 1, the switch SW20 shown in FIG. 17 is turned on. For this reason, the capacitor CR3 is connected between the output terminal 34 of the drive circuit 3 and the input terminal 44 of the voltage detection circuit 4A.
Here, the calculation process in which the voltage detection circuit 4A detects eight voltages according to the drive patterns 1 to 8 can be expressed by the above equation (6).

Each of the eight rows of the Hadamard transform matrix corresponds to the eight drive patterns 1 to 8 described above. Further, 1 and −1 in each row correspond to the connection state between the X lines X1 to X8 of each drive pattern and the drive circuit 3.
Output voltages D1 to D8 output from the voltage detection circuit 4A are A / D converted by the A / D conversion circuit 5, respectively. The A / D converted output voltages D1 to D8 are sequentially stored in the capacity calculation circuit 6A.

When the storage of the output voltages D1 to D8 is completed, the capacity calculation circuit 6A performs an operation for calculating the capacitances C1 to C8 based on the stored output voltages D1 to D8 and the Hadamard transform matrix as a conversion matrix. Do. The arithmetic processing performed by the capacity calculation circuit 6A can be expressed by the above equation (7).
The touch position detection circuit 7A detects the touch position of the touch panel 1 based on the capacitances C1 to C8 calculated by the capacitance calculation circuit 6A.

The above operation is an example in which the touch position on the touch panel 1 is detected by a one-dimensional operation. However, when the touch position on the touch panel 1 is detected by a two-dimensional operation, the above operation is repeated. become.
In this case, the connection between the Y lines Y1 to Y8 and the voltage detection circuit 4A is sequentially changed, and for each change, the voltage detection circuit 4A detects eight voltages according to the drive patterns 1 to 8. Perform arithmetic processing.

As described above, in the third embodiment, since the voltage detection circuit 4A is configured as a single type as shown in FIG. 17, the configuration is simplified.
In the third embodiment, the capacitor CR3 and the switch SW20 shown in FIG. 17 may be omitted. In this case, the detection in the case of FIG. 18A is omitted, and a fixed value such as 0 is used as the measurement value.

In the third embodiment, an Hadamard transformation matrix of 8 rows × 8 columns is used as shown in the equation (6). However, a Hadamard transform matrix such as 4 rows × 4 columns or 16 rows × 16 columns can also be used.
For this reason, when the Hadamard transformation matrix of n rows × n columns (n = 2, multiple of 4) is used, the number of the driving patterns is n, and the driving circuit 3 is connected according to each driving pattern. There are n drive lines. In the above example, there are eight drive patterns as shown in FIGS. 18 and 19, and there are eight drive lines connected to the drive circuit 3 in accordance with these eight drive patterns.

(Modification of the operation of the third embodiment)
When multi-point touch detection is not required, the X and Y coordinates of the touch position can be detected by performing the following operation instead of the operation of the second embodiment.
First, the selection circuit 2 selects all Y lines instead of selecting one predetermined line as a detection line from among the Y lines Y1 to Y8 of the touch panel 1 in accordance with a predetermined detection pattern. . The rest is the same as the description of the operation of the third embodiment. Thereby, the X coordinate of the touch position can be detected. Next, the above operation is performed again by exchanging the X line and the Y line. Thereby, the Y coordinate of the touch position can be detected.

(Configuration of Fourth Embodiment)
FIG. 20 is a block diagram showing a schematic configuration of a touch sensor to which the fourth embodiment of the present invention is applied.
As shown in FIG. 20, the touch sensor to which the fourth embodiment is applied includes a touch panel 1, a selection circuit 2, a drive circuit 3, a voltage detection circuit 4, an A / D conversion circuit 5, and a capacitance calculation circuit. 6B, a touch position detection circuit 7B, a control circuit 8C, an address generation circuit 9, a memory 10, a latch 11, and a capacitance circuit 12 for offset adjustment.
That is, the fourth embodiment is based on the configuration of the second embodiment shown in FIG. 11. As shown in FIG. 20, the capacitance calculation circuit 6A, the touch position detection circuit 7A, and the control circuit 8A shown in FIG. The calculation circuit 6B, the touch position detection circuit 7B, and the control circuit 8C are replaced.

Here, the fourth embodiment has parts common to the components of the second embodiment, and the common components are denoted by the same reference numerals, and description thereof is omitted as much as possible.
The control circuit 8C controls the drive circuit 3, the voltage detection circuit 4, the address generation circuit 9, the latch 11, and the capacitance circuit 12 when detecting the touch position of the touch panel 1.

(Operation of Fourth Embodiment)
Next, a case where the touch position of the touch panel 1 is detected in the fourth embodiment will be described with reference to FIGS.
First, when one of 64 conversion patterns (combination of drive pattern and detection pattern) that is predetermined according to a predetermined conversion matrix is selected, the selection circuit 2 selects the selected conversion pattern. Accordingly, a part of the Y lines Y1 to Y8 of the touch panel 1 is connected to the output terminal 33 of the drive circuit 3, and the rest of the Y lines Y1 to Y8 is connected to the output terminal 34 of the drive circuit 3.

Further, when the above conversion pattern is selected, the selection circuit 2 selects a part of the X lines X1 to X8 of the touch panel 1 according to the selected conversion pattern as the input terminal 44 of the voltage detection circuit 4. And the remainder of the X lines X 1 to X 8 is connected to the input terminal 45 of the voltage detection circuit 4.
21 to 36 show 64 conversion patterns determined according to the Hadamard transformation matrix, the connection states of the Y lines Y1 to Y8 and the drive circuit 3 according to these 64 conversion patterns, and the X lines X1 to X1. The connection state between X8 and the voltage detection circuit 4 is shown.

Here, FIG. 21 and FIG. 22 show eight conversion patterns obtained by combining pattern 1 and eight patterns 1-8. 23 and 24 show eight conversion patterns obtained by combining the pattern 2 and the eight patterns 1 to 8. FIG. 25 and 26 show eight conversion patterns obtained by combining the pattern 3 and the eight patterns 1 to 8. 27 and 28 show eight conversion patterns obtained by combining the pattern 4 and the eight patterns 1 to 8. FIG.

29 and 30 show eight conversion patterns obtained by combining pattern 5 and eight patterns 1-8. 31 and 32 show eight conversion patterns obtained by combining the pattern 6 and the eight patterns 1 to 8. 33 and 34 show eight conversion patterns obtained by combining the pattern 7 and the eight patterns 1-8. 35 and 36 show eight conversion patterns obtained by combining the pattern 8 and the eight patterns 1 to 8. FIG.

21 to 36, the Y axis is connected to the drive circuit 3 and the X axis is connected to the voltage detection circuit 4, but the X axis is connected to the drive circuit 3 and the Y axis is connected to the voltage detection circuit 4. You may make it the structure to carry out. Moreover, you may change whether the drive circuit 3 and the voltage detection circuit 4 are connected to an X-axis or a Y-axis for every pattern. In the examples of FIGS. 21 and 22, the voltage detection circuit 4 has a single-ended configuration. In this case, except for the case of FIG. 21A, voltage detection is performed by switching the + terminal of the drive circuit 3 and the + terminal of the voltage detection circuit 4 and switching the − terminal of the drive circuit 3 and the − terminal of the voltage detection circuit 4. By modifying the circuit 4 to a differential configuration, the voltage detection circuit 4 having a differential configuration is used in all patterns except the pattern of FIG. 21A, and the S / N is further improved. Can do. Further, even if the + terminal of the drive circuit 3 and the + terminal of the voltage detection circuit 4 and the − terminal of the drive circuit 3 and the − terminal of the voltage detection circuit 4 are interchanged, the operation of the capacitance calculation circuit 6B may be the same. Further, by omitting the measurement of FIG. 21A and treating the measured value as 0, a conversion pattern may be configured so as not to use the single-ended voltage detection circuit at all, and the S / N is further improved. Can do.
Assuming that the capacitance formed between the axis Xi and the axis Yj is Cij, the relationship with the value appearing at the output Dmn of the voltage detection circuit 4 is expressed by the following equation (7A).

21 to 36, the sign “+” in the figure is s _mi s _nj = + 1, and the sign “−” is s _mi s _nj = −1. s _mi and s _nj are the (m, i) component and (n, j) component of the Hadamard transform matrix expressed by the following equation (9), respectively.
Next, for each of the 64 conversion patterns, the drive circuit 3 and the voltage detection circuit 4 perform the operations of “state 1” and “state 2” shown in FIG. 5, and the voltage detection circuit 4 A potential difference corresponding to the conversion pattern is detected.
Here, the calculation process in which the voltage detection circuit 4 detects the voltage corresponding to the potential difference in accordance with the 64 conversion patterns can be expressed by the following equation (8). Note that the terms VCOM and VDD / Cf in equation (7A) are irrelevant to capacitance calculation and touch position detection, and are therefore omitted for the sake of brevity.

In the equation (8), D is 64 output voltages (detected voltages) of the voltage detection circuit 4 obtained according to the 64 conversion patterns, and is an 8 × 8 matrix. H on the right side of equation (8) is the Hadamard transform matrix shown in equation (9).
In the equation (8), C is 64 capacitances at the intersections of the X lines X1 to X8 and the Y lines Y1 to Y8 of the touch panel 1, and is an 8 × 8 matrix. Further, the H on the right side of equation (8) and the subscript T attached to the right shoulder is obtained by replacing the rows and columns of the Hadamard transform matrix of equation (9).

The 64 output voltages output from the voltage detection circuit 4 are each A / D converted by the A / D conversion circuit 5 at a predetermined timing of the operation of “state 2” in FIG. The A / D converted output voltages are sequentially stored in the capacity calculation circuit 6B. When the storage of the output voltage is completed, the capacitance calculation circuit 6B, based on the stored output voltage and the Hadamard transformation matrix that is a transformation matrix, each of the X lines X1 to X8 and the Y lines Y1 to Y8 of the touch panel 1 is stored. An operation for calculating each of the 64 capacitances at the intersection is performed.
The arithmetic processing performed by the capacity calculation circuit 6B can be expressed by the following equation (10).

The touch position detection circuit 7B detects the touch position of the touch panel 1 based on the 64 electrostatic capacitances calculated by the capacity calculation circuit 6B.
As described above, in the fourth embodiment, the voltage detection circuit 4 performs arithmetic processing according to the 64 conversion patterns to obtain 64 output voltages, respectively, and the difference is obtained when each output voltage is obtained. Dynamic amplification was performed. For this reason, when obtaining each output voltage, noise can be reduced and S / N can be improved.
In the fourth embodiment, an Hadamard transformation matrix of 8 rows × 8 columns is used as shown in equations (8) and (9). However, a Hadamard transformation matrix such as 2 rows × 2 columns, 4 rows × 4 columns, 16 rows × 16 columns, or the like can also be used.

Further, when using a Hadamard transform matrix of m rows × m columns (m = 2, multiple of 4) in the X axis direction and n rows × n columns (n = 2, multiples of 4) in the Y axis direction, The number of the conversion patterns is (m × n), and according to each conversion pattern, the number of drive lines connected to the drive circuit 3 is m, and the number of detection lines connected to the voltage detection circuit 4 is n. Become.
In the above example, there are 64 conversion patterns as shown in FIGS. 21 to 36, 8 drive lines connected to the

drive circuit

3, and 8 detection lines connected to the voltage detection circuit 4.

(Modification 1 of 4th Embodiment)
The configuration and operation of Modification 1 of the fourth embodiment are basically the same as those of the fourth embodiment. Hereinafter, a different part from 4th Embodiment is demonstrated.
Among X lines X1 to X8, X1 and X2 are grouped into X line group 1, X3 and X4 are grouped into X line group 2, X5 and X6 are grouped into X line group 3, and X7 and X8 are grouped into X line group 4. That is, the X lines X1 to X8 are divided into four groups.
On the other hand, among Y lines Y1 to Y8, Y1, Y2, Y3, Y4 are grouped into Y line group 1, and Y5, Y6, Y7, Y8 are grouped into Y line group 2. That is, the Y lines Y1 to Y8 are divided into two groups.

Suppose that the electrodes that are easted by the above grouping are regarded as one electrode, it can be seen that the X line is four and the Y line is two panels. After that, similarly to the fourth embodiment, it is possible to create a drive / detection pattern in which the Hadamard transform of 4 rows × 4 columns is applied to the X line and the Hadamard transform of 2 rows × 2 columns is applied to the Y line. All combinations of patterns are shown in FIGS. The grouping of the X line and the Y line is indicated by a symbol “{”.

The drive / detection patterns shown in FIGS. 37 and 38 are stored in the memory 10, and the selection circuit 2, the drive circuit 3, the voltage detection circuit 4, and the A / D conversion circuit 5 are operated in the same manner as in the fourth embodiment. The A / D converted value is acquired. After that, in the capacity calculation circuit 6B, the X line is 4 groups, so the 4 rows × 4 columns Hadamard transform is used, and the Y line is 2 groups, so the 2 rows × 2 columns Hadamard transform is used. The same processing as in the fourth embodiment is performed.

As a result, the total capacitance formed at the intersection of X line X1, X2 and Y line Y1, Y2, Y3, Y4, and at the intersection of X line X1, X2 and Y line Y5, Y6, Y7, Y8. Total capacitance formed, total capacitance formed at the intersection of X line X3, X4 and Y line Y1, Y2, Y3, Y4, X line X3, X4 and Y line Y5, Y6, Y7 , Y8, the total capacitances formed at the intersections are respectively obtained. Furthermore, the total capacitance formed at the intersection of X line X5, X6 and Y line Y1, Y2, Y3, Y4, formed at the intersection of X line X5, X6 and Y line Y5, Y6, Y7, Y8 The total capacitance formed, the total capacitance formed at the intersection of X lines X7, X8 and Y lines Y1, Y2, Y3, Y4, X lines X7, X8 and Y lines Y5, Y6, Y7, The total capacitance formed at the intersection of Y8 is determined. As described above, Modification 1 of the fourth embodiment has a smaller number of measurement points than the fourth embodiment, and is convenient for operation in a low power consumption mode. In addition, since the capacity change for each group can be greatly increased as the spatial resolution is reduced, it is particularly convenient for detecting hovering.

(Modification 2 of 4th Embodiment)
Modification 2 is a case where the number of touch panel lines (number of electrodes) is not a multiple of 4, for example, 7 in the X-axis direction and 9 in the Y-axis direction.
In the second modification, the basic configuration is the same as that in FIG. 20, and only the size of the touch panel 1 is different. The operation is the same as that of the fourth embodiment. Only the parts different from the fourth embodiment will be described below.

¡Select the size of the Hadamard transform matrix in multiples of 4 greater than the number of electrodes in the X-axis and Y-axis directions. Here, since the number of electrodes in the X-axis direction is 7, an Hadamard transformation matrix of 8, that is, 8 rows × 8 columns, is used as the minimum multiple of 4 in the X-axis direction. Since the number of electrodes in the Y-axis direction is 9, 12 is used as the minimum multiple of 4 in the Y-axis direction, that is, a 12-row × 12-column Hadamard transformation matrix is used.

According to the Hadamard transformation matrix of the selected size, 8 types in the X-axis direction, 12 types in the Y-axis direction, and 8 × 12 = 96 types of conversion patterns, which are all combinations thereof, are used.
Assuming that the capacitance formed between the axis X _i and the axis Y _j is C ij, the relationship with the value appearing at the output Dmn of the voltage detection circuit 4 is as shown in equation (11).

However, m = 1, 2,..., 8 and n = 1, 2,.
s _mi is the (m, i) component of the aforementioned 8-row × 8-column Hadamard transform matrix, and s _nj ′ is the (n, j) component of the aforementioned 12-row × 12-column Hadamard transform matrix. However, since i = 1, 2,..., 7 and j = 1, 2,..., 9, some components of the Hadamard transform matrix are not used.

Next, for each of the 96 conversion patterns, the drive circuit 3 and the voltage detection circuit 4 perform the operations of “state 1” and “state 2” shown in FIG. 5, and the voltage detection circuit 4 performs the 96 conversions. A potential difference corresponding to the pattern is detected.
Here, the calculation process in which the voltage detection circuit 4 detects the voltage corresponding to the potential difference in accordance with the 96 conversion patterns can be expressed by the following equation (12). Note that the terms VCOM and VDD / Cf in equation (11) are irrelevant to the capacitance calculation and the touch position detection, and are therefore omitted for simplification.

The calculation process performed by the capacity calculation circuit 6B can be expressed by the following equation (14).

However, H _x is the 8th row × 8th column Hadamard transformation matrix as shown in the equation (13A), and the 8th column (the rightmost column) is deleted to make the number of columns the number of electrodes in the X-axis direction. This is a matrix representation of s _mi in equation (11). Note that the position of the column to be deleted may be anywhere, and the number of columns as a result of deleting the column only needs to match the number of electrodes in the X-axis direction. The transposed matrices H _x ^T and H _x are in a Moore-Penrose generalized inverse matrix (scalar multiple). Also, H _y is the number of columns in the Y-axis direction to remove the 10-12 column of the Hadamard transform matrix of 12 rows × 12 columns as expressed by (13B) (3 rows of rightmost) This corresponds to the number of electrodes, and is a matrix representation of s _nj ′ in equation (11). Note that the position of the column to be deleted may be anywhere, and the number of columns as a result of deleting the column only needs to match the number of electrodes in the Y-axis direction. The columns to be deleted need not be adjacent to each other. The transposed matrices H _y ^T and H _y are in a Moore-Penrose generalized inverse matrix (scalar multiple).

Although the output voltage output from the voltage detection circuit 4 is 96 and more than 63 electrodes, H _x ^T and H _{y in the} equation (14) are generalizations of H _x and H _y ^{T in} the equation (12), respectively. Since it is an inverse matrix, the obtained C _ij is a least squares solution that satisfies the equation (11). Therefore, the greater the number of output voltages of the voltage detection circuit 4, the better the S / N.
In Modification 2, H _x and H _y are obtained by deleting some of the rows of the Hadamard transformation matrix, but not only the Hadamard transformation matrix but also an orthogonal transformation matrix and a scalar multiple of the orthogonal transformation matrix. Since the transposed matrix of the matrix from which a part of the column is deleted becomes a Moore-Penrose generalized inverse matrix (scalar multiple) of the original matrix, this variation can be applied.

The touch position detection circuit 7B detects the touch position of the touch panel 1 based on the 63 electrostatic capacitances calculated by the capacitance calculation circuit 6B.
This modification can be applied even when the number of electrode groups by grouping is not 2 or a multiple of 4 in Modification 1 of the fourth embodiment.

(Fifth embodiment)
In the fifth embodiment, as shown in FIG. 1, the touch panel 1, the selection circuit 2, the drive circuit 3, the voltage detection circuit 4, the A / D conversion circuit 5, the capacitance calculation circuit 6, the touch position detection circuit 7, and the control circuit 8. , An address generation circuit 9, a memory 10, and a latch 11. However, the capacity calculation circuit 6, the touch position detection circuit 7, the control circuit 8, and the like can be replaced with a computer.

Therefore, in the fifth embodiment, functions such as the capacity calculation circuit 6, the touch position detection circuit 7, and the control circuit 8 shown in FIG. 1 are replaced with a computer (not shown), and the computer performs the selection circuit 2 and the drive circuit 3 The operation of the voltage detection circuit 4 and the like are controlled, and the calculation processing of the capacitance calculation circuit 6 and the touch position detection circuit 7 is performed.
For this reason, in the fifth embodiment, as shown in FIG. 37, procedures (programs) of various processes such as various predetermined controls and calculations are stored in advance in, for example, the memory 10 of FIG. The computer performed various processing such as control and calculation.

Next, with reference to FIG. 1 and FIG. 37, each process of control of each part and calculation by the computer of 5th Embodiment is demonstrated.
Here, each of the plurality of addresses of the memory 10 of FIG. 1 includes a selection circuit 2 for each detection pattern determined according to a predetermined drive pattern and a predetermined conversion matrix (for example, Hadamard conversion matrix). It is assumed that control data for controlling operations of the drive circuit 3 and the voltage detection circuit 4 is stored in advance.

In step S1, in order to read out control data corresponding to the drive pattern and detection pattern stored in the memory 10, the address of the memory 10 is set to the start address.
In step S2, control data corresponding to the drive and detection patterns stored at the start address of the set memory 10 is read.
In step S3, the switches SW11 to SW15 of the switch units 21-1 to 21-8 of the selection circuit 2 are on / off controlled based on the control data, and the switches of the selection circuit 2 are set.

As a result, a predetermined line among the Y lines Y1 to Y8 of the touch panel 1 is selected as a drive line and connected to the output terminal of the drive circuit 3. A part of the X lines X 1 to X 8 of the touch panel 1 is connected to one input terminal of the voltage detection circuit 4, and the rest is connected to the other input terminal of the voltage detection circuit 4.
In step S4, the operation of the drive circuit 3 and the voltage detection circuit 4 is set to “state 1” based on the control data stored at the start address of the memory 10 (see FIG. 5). This setting is performed by controlling the switches SW1 to SW4 of the drive circuit 3 and the switches SW5 and SW6 of the voltage detection circuit 4.

After the setting, the process waits for a predetermined time in step S5, and when this standby is completed, the process proceeds to the next step S6.
In step S6, the operation of the drive circuit 3 and the voltage detection circuit 4 is set to “state 2” based on the control data stored at the start address of the memory 10 (see FIG. 5). After this setting, in step S7, the process waits for a predetermined time, and this standby is completed.

With the above setting, the voltage detection circuit 4 detects the voltage difference between the input voltages input to its two input terminals, and outputs the detected voltage to the A / conversion circuit 5.
In step S8, an A / D conversion value output from the A / D conversion circuit 5 is acquired.
In step S9, the acquired A / D conversion value is stored.
In step S10, it is determined whether or not the current address of the memory 10 is an end address. As a result of this determination, if it is not the end address (NO), the address is incremented (step S11), the process returns to step S2, and a series of processes of steps S2 to S10 is performed. On the other hand, in the case of an end address (YES), the process proceeds to step S12.

In step S12, the capacitance difference is calculated by performing Hadamard inverse transformation based on the A / D conversion value stored in step S9. This calculation corresponds to the function of the capacity calculation circuit 6 of FIG.
In step S13, the touch position is detected based on the capacitance difference calculated in step S12. This detection corresponds to the function of the touch position detection circuit 7 in FIG.

In step S14, the coordinates of the touch position detected in step S13 are output.
As described above, in the fifth embodiment, functions such as the capacity calculation circuit 6, the touch position detection circuit 7, and the control circuit 8 shown in FIG. 1 are replaced with a computer.
However, in the second embodiment of FIG. 11, the functions of the capacitance calculation circuit 6A, the touch position detection circuit 7A, the control circuit 8A, and the like may be replaced with a computer. In the third embodiment shown in FIG. 16, the functions of the capacitance calculation circuit 6A, the touch position detection circuit 7A, the control circuit 8B, and the like may be replaced with a computer. Furthermore, in the fourth embodiment of FIG. 20, the functions of the capacity calculation circuit 6B, the touch position detection circuit 7B, the control circuit 88C, and the like may be replaced with a computer.

When the computer is replaced in this way, the control of each part and the calculation processing by the computer of each of the second to fourth embodiments can be realized by the same procedure as the flowchart shown in FIG.
However, each of the second to fourth embodiments includes

capacitance circuits

12 and 12A as shown in FIG. 11, FIG. 16, or FIG. For this reason, in the flowchart of FIG. 37, a process for setting the capacitance circuit switch and the capacitance value is added between step S3 and step S4.

The signal processing circuit of the touch sensor of the present invention can be applied not only to the touch sensor but also to a display device including the touch sensor.

DESCRIPTION OF SYMBOLS 1 ... Touch panel 2 ... Selection circuit 3 ... Drive

circuit

4, 4A ... Voltage detection circuit 5 ... A /

D conversion circuit

6, 6A, 6B ...

Capacity calculation circuit

7, 7A, 7B: Touch

position detection circuit

8, 8A to 8C ... Control circuit 9 ... Address generation circuit 10 ... Memory 11 ...

Latch

12, 12A ... Capacitance circuit 21-1 to 21 -8, 22-1 to 22-8 ... Switch section 23-1 to 23-8, 24-1 to 24-8 ... Decoder 25 to 29 ... Connection line SW1 to SW6 ... Switch SW11 ~ SW15 ... Switch

Claims

A signal processing circuit of a touch sensor including a touch panel comprising: a plurality of first lines; and a plurality of second lines arranged to intersect the plurality of first lines via an insulating layer. ,
A first drive terminal and a second drive terminal, a first detection terminal and a second detection terminal, and an output terminal, connected between the first drive terminal and the first detection terminal The first capacitance difference is obtained as a difference between the measured first capacitance and the second capacitance connected between the second drive terminal and the first detection terminal. A third capacitance connected between the second drive terminal and the second detection terminal, and a fourth capacitance connected between the second drive terminal and the second detection terminal. A capacitance measurement circuit that obtains the difference between the first capacitance difference and the second capacitance difference as a second signal, converts the difference between the first capacitance difference and the second capacitance difference into a predetermined signal, and outputs the difference.
One or more lines are selected as the first drive line group from among the plurality of first lines, or 0 different from the first drive line group in addition to the first drive line group Selecting the above lines as a second drive line group, connecting the first drive line group to the first drive terminal, connecting the second drive line group to the second drive terminal, In addition, zero or more lines are selected as the first detection line group from the plurality of second lines, and one or more lines different from the first detection line group are selected as the second detection lines. A selection circuit for selecting as a group, connecting the first detection line group to the first detection terminal, and connecting the second detection line group to the second detection terminal;
A signal processing circuit for a touch sensor, comprising:
The selection circuit includes:
Each time one detection pattern is selected from among a plurality of detection patterns determined according to a predetermined conversion matrix, the plurality of second lines are selected according to the selected detection pattern. 2. At least one line is selected as the first drive line group, and at least one line different from the first drive line group is selected as the second drive line group. A signal processing circuit of the touch sensor as described in 1.
An operation is performed based on the output signal of the capacitance measuring circuit and the conversion matrix, and at each intersection between the selected first drive line group and the selected first and second detection line groups. The electrostatic capacity of the difference between the electrostatic capacity and the corresponding electrostatic capacity at each intersection of the selected second drive line group and the selected first and second detection line groups. The touch sensor signal processing circuit according to claim 2, further comprising a capacitance calculation circuit for calculating each capacitance.
The selection circuit includes:
Each time one detection pattern is selected from among a plurality of detection patterns determined according to a predetermined transformation matrix, the plurality of first lines are selected according to the selected detection pattern. One or more lines are selected as the first drive line group, the selected first drive line group is connected to the first drive terminal, and the second drive terminal and the first detection are selected. A first offset adjustment capacitor having a predetermined capacitance value is connected between the terminals, and a second capacitance value having a predetermined capacitance value between the second drive terminal and the second detection terminal is connected. The touch sensor signal processing circuit according to claim 1, further comprising an offset adjustment capacitor connected thereto.
A capacitance calculation circuit that performs an operation based on the output signal of the capacitance measurement circuit and the conversion matrix, and calculates a capacitance at each intersection of the selected drive line and each selected detection line; The touch sensor signal processing circuit according to claim 4, further comprising:
6. The touch sensor signal processing circuit according to claim 2, wherein the transformation matrix is a Hadamard transformation matrix.
The Hadamard transform matrix is composed of n rows × n columns (n = 2, multiple of 4), the plurality of detection patterns are n detection patterns, and the selected first and second detection line groups 7. The touch sensor signal processing circuit according to claim 6, wherein the total number of lines to which the number belongs is n.
The selection circuit includes:
Each time one drive pattern is selected from among a plurality of drive patterns determined according to a predetermined conversion matrix, the plurality of first lines are selected according to the selected drive pattern. One or more lines are selected as a first drive line group, and zero or more lines different from the first drive line group among the plurality of first lines as a second drive line group Selected,
Each time one detection pattern is selected from among a plurality of detection patterns determined according to the predetermined conversion matrix, the plurality of second lines are selected according to the selected detection pattern. Then, one or more lines are selected as the first detection line group, and zero or more lines different from the first detection line group among the plurality of second lines are selected as the second detection line group. The signal processing circuit of the touch sensor according to claim 1, wherein:
The calculation is performed based on the output signal of the capacitance measuring circuit and the conversion matrix, and the capacitances of the capacitance matrix formed at the intersections of the plurality of first lines and the plurality of second lines are calculated. 9. The signal processing circuit of the touch sensor according to claim 8, further comprising a capacitance calculating circuit for calculating.
10. The touch sensor signal processing circuit according to claim 8, wherein the transformation matrix is a Hadamard transformation matrix.
When the Hadamard transform matrix is m rows × m columns (m = 2, a multiple of 4) in the first direction and n rows × n columns (n = 2, a multiple of 4) in the second direction, The number of combinations of the drive patterns and the detection patterns is (m × n), and the total number of lines belonging to the selected first and second drive line groups is m in accordance with each drive pattern and detection pattern, 11. The touch sensor signal processing circuit according to claim 10, wherein the total number of lines belonging to the selected first and second detection lines is n.
The selection circuit includes:
For each of the plurality of drive patterns, a line connected to the first drive terminal and a line connected to the second drive terminal are changed,
The line connected to the first detection terminal and the line connected to the second detection terminal are changed according to the change of the line connected to the first drive terminal and the second drive terminal. The signal processing circuit of the touch sensor according to any one of claims 8 to 11.
The selection circuit includes:
The connection of the line selected as the line connected to the first drive terminal to the connection to the first detection terminal is changed to the connection to the first detection terminal and selected as the line connected to the second drive terminal The connection of the selected line to the second detection terminal is changed to the connection to the second detection terminal, and the connection of the line selected as the line to be connected to the first detection terminal is connected to the first detection terminal. The connection to the first drive terminal is changed, and the connection to the second detection terminal of the line selected as the line to be connected to the second detection terminal is changed to the connection to the second drive terminal. The signal processing circuit for a touch sensor according to claim 8, wherein the signal processing circuit is a touch sensor.
The transformation matrix uses a first transformation matrix and a second transformation matrix, and one of the first transformation matrix and the second transformation matrix is equal to or more than the number of the plurality of first lines. Or a second transformation matrix having a size equal to or larger than the number of the plurality of second lines, wherein the plurality of detection patterns include the first transformation matrix and the first transformation matrix. 2 in advance, and when the size of the first transformation matrix is equal to or larger than the number of the plurality of first lines, the row vector or column of the first transformation matrix When a third transformation matrix excluding a part of the vector is used as the first transformation matrix and the size of the second transformation matrix is equal to or larger than the number of the plurality of second lines, Part of the row or column vector of the second transformation matrix Determined in advance using a fourth transformation matrix except as the second conversion matrix,
The said capacity | capacitance calculation part uses each transposed matrix of those of said 1st conversion matrix and said 2nd conversion matrix, or each of those generalized inverse matrix, The any one of Claims 8 thru | or 11 characterized by the above-mentioned. A signal processing circuit of the touch sensor according to claim 1.
The touch position detection circuit for detecting the touch position on the touch panel based on each capacitance calculated by the capacitance calculation circuit is further provided. The signal processing circuit of the touch sensor according to any one of claims.
The transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines,
The plurality of detection patterns are a matrix in which the number of rows or columns is made equal to the number of the plurality of first lines or the plurality of second lines except for a part of the row vector or column vector of the transformation matrix. Predetermined based on
The touch sensor signal processing according to claim 3, wherein the capacitance calculation circuit uses a transposed matrix or a generalized inverse matrix of the matrix. circuit.
The capacity calculation circuit includes:
6. The touch sensor according to claim 3, wherein when the detection pattern is a predetermined detection pattern among the plurality of detection patterns, the output signal of the capacitance measurement circuit is processed as 0. 7. Signal processing circuit.
The capacity calculation circuit includes:
The touch sensor signal processing circuit according to claim 9, wherein an output signal of the capacitance measuring circuit is processed as 0 when a predetermined detection pattern and drive pattern among the plurality of detection patterns and drive patterns are used.
A signal processing circuit of a touch sensor including a touch panel comprising: a plurality of first lines; and a plurality of second lines arranged to intersect the plurality of first lines via an insulating layer. ,
A first capacitance having a first drive terminal and a second drive terminal, a detection terminal, and an output terminal, connected between the first drive terminal and the detection terminal; A capacitance measuring circuit that converts a difference between the second electrostatic capacitance connected between the two drive terminals and the detection terminal into a predetermined signal and outputs the predetermined signal;
Each time one drive pattern is selected from among a plurality of drive patterns determined according to a predetermined conversion matrix, the plurality of first lines are selected according to the selected drive pattern. One or more lines are selected as the first drive line group, or in addition to the first drive line group, zero or more lines different from the first drive line group are selected as the second drive line group The first drive line group is connected to the first drive terminal, the second drive line group is connected to the second drive terminal, and the plurality of second lines A selection circuit that selects one or more lines as a detection line group from among them, and connects the detection line group to the detection terminal;
Calculation is performed based on each predetermined signal detected by the capacitance measurement circuit and the conversion matrix, and capacitances at respective intersections of the selected drive line and the selected detection lines are respectively calculated. A capacity calculation circuit;
A signal processing circuit for a touch sensor, comprising:
20. The touch sensor signal processing circuit according to claim 19, wherein the transformation matrix is a Hadamard transformation matrix.
The Hadamard transform matrix is composed of n rows × n columns (n = 2, a multiple of 4), the plurality of detection patterns are n drive patterns, and the selected first and second drive line groups 21. The touch sensor signal processing circuit according to claim 20, wherein the total number of lines to which the number belongs is n.
The touch position detection circuit for detecting a touch position on the touch panel based on each capacitance calculated by the capacity calculation circuit, further comprising: a touch position detection circuit. A signal processing circuit of the touch sensor as described in 1.
The transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines,
The plurality of detection patterns are a matrix in which the number of rows or columns is made equal to the number of the plurality of first lines or the plurality of second lines except for a part of the row vector or column vector of the transformation matrix. Predetermined based on
The signal processing circuit of the touch sensor according to any one of claims 19 to 21, wherein the capacitance calculation circuit uses a transposed matrix or a generalized inverse matrix of the matrix.
The capacity calculation circuit includes:
The touch sensor according to any one of claims 19 to 21, wherein an output signal of the capacitance measurement circuit is processed as 0 when the drive pattern is a predetermined drive pattern among the plurality of drive patterns. Signal processing circuit.
A touch sensor comprising the touch sensor signal processing circuit according to any one of claims 1 to 24.
A touch panel comprising a plurality of first lines and a plurality of second lines arranged to intersect the plurality of first lines via an insulating layer;
A drive circuit having a first output terminal and a second output terminal for outputting a drive voltage;
A voltage detection circuit that detects a differential voltage between a first voltage corresponding to the input voltage of the first input terminal and a second voltage corresponding to the input voltage of the second input terminal;
A selective connection between the plurality of first lines and a first output terminal or a second output terminal of the drive circuit; and the plurality of second lines and a first input of the voltage detection circuit. A selection circuit for performing selective connection between the terminal or the second input terminal;
A signal processing method for a touch sensor including:
Computer
One pattern is selected from a plurality of patterns determined according to a predetermined transformation matrix, and one or more lines are selected from the plurality of first lines according to the selected pattern. Is selected as the first drive line group, or in addition to the first drive line group, zero or more lines different from the first drive line group are selected as the second drive line group, and the first drive line group is selected. The operation of the selection circuit is controlled so that one drive line group is connected to the first output terminal of the drive circuit, and the second drive line group is connected to the second output terminal of the drive circuit. The first step;
One or more lines are selected as the first detection line group from the plurality of second lines, and zero or more lines different from the first detection line group are used as the second detection line group. Selecting, connecting the first detection line group to a first input terminal of the voltage detection circuit, and connecting the second detection line group to a second input terminal of the voltage detection circuit, A second step for controlling the operation of the selection circuit;
A third step of controlling the operation of the drive circuit so that the drive circuit outputs a predetermined drive voltage, and controlling the operation of the voltage detection circuit so that the voltage detection circuit detects the differential voltage;
A fourth step of performing an operation based on the output signal of the voltage detection circuit and the conversion matrix, and calculating a capacitance at each intersection of the selected drive line and each selected detection line; ,
The signal processing method of the touch sensor characterized by performing this.
In the first step, the plurality of first lines and the plurality of second lines are selected as the first drive line group and the second drive line group for each of the plurality of patterns. change,
In the second step, the plurality of first lines and the plurality of second lines are used as the first detection line group and the second detection line group in accordance with the change in the first step. 27. The touch sensor signal processing method according to claim 26, wherein selection is changed.
When the predetermined pattern of the plurality of patterns,
In the first step, the connection of the selected first drive line group to the first output terminal of the drive circuit is changed to the connection to the first input terminal of the voltage detection circuit, and the selected first Changing the connection of the second drive line group to the second output terminal of the drive circuit to the second input terminal of the voltage detection circuit;
In the second step, the connection of the selected first detection line group to the first input terminal of the voltage detection circuit is changed to the connection to the first output terminal of the drive circuit, and the selected first detection line group 27. The signal of the touch sensor according to claim 26, wherein the connection of the second detection line group to the second input terminal of the voltage detection circuit is changed to the connection to the second output terminal of the drive circuit. Processing method.
When the predetermined pattern among the plurality of patterns,
27. The signal processing of the touch sensor according to claim 26, wherein each processing from the first step to the third step is omitted, and the output signal of the voltage detection circuit is processed as 0 in the fourth step. Method.
The transformation matrix uses a transformation matrix having a size equal to or larger than the number of the plurality of first lines or the plurality of second lines,
The plurality of patterns is a matrix in which the number of rows or columns is made equal to the number of the plurality of first lines or the plurality of second lines excluding a part of the row vector or column vector of the transformation matrix. Predetermined based on
In each process of the first step and the second step, the plurality of predetermined detection patterns are used,
27. The touch sensor signal processing method according to claim 26, wherein a transpose matrix or a generalized inverse matrix of the matrix is used in the process of the fourth step.
The transformation matrix uses a first transformation matrix and a second transformation matrix, and one of the first transformation matrix and the second transformation matrix is equal to or more than the number of the plurality of first lines. Or a second transformation matrix having a size equal to or larger than the number of the plurality of second lines,
The plurality of patterns are predetermined based on the first transformation matrix and the second transformation matrix, and the size of the first transformation matrix is equal to or larger than the number of the plurality of first lines. In this case, a third transformation matrix excluding a part of a row vector or a column vector of the first transformation matrix is used as the first transformation matrix, and the size of the second transformation matrix is the plurality of the second transformation matrices. When the size is equal to or larger than the number of lines of 2, a fourth transformation matrix excluding a part of a row vector or a column vector of the second transformation matrix is used as the second transformation matrix, and is determined in advance.
In each process of the first step and the second step, a plurality of patterns defined by the first transformation matrix and the second transformation matrix are used,
27. The touch sensor according to claim 26, wherein in the processing of the fourth step, transpose matrices of the first transformation matrix and the second transformation matrix or their respective generalized inverse matrices are used. Signal processing method.
32. The touch sensor signal processing method according to claim 26, wherein the transformation matrix is a Hadamard transformation matrix.
27. A touch sensor signal processing program that causes a computer to execute each step in the touch sensor signal processing method according to claim 26.