JP2013246556A - Touch sensor signal processing circuit and touch sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel signal processing circuit capable of reducing noise generated when a touch panel is touched by a finger as well as improving the S/N ratio.SOLUTION: A selection circuit 2 selects two of Y lines Y1-Y8 as drive lines, and selects at least two of X lines X1-X8 as detection lines in accordance with a detection pattern selected from a plurality of detection patterns defined in accordance with a transformation matrix. A drive circuit 3 supplies voltage to each of the selected drive lines. A voltage detection circuit 4 detects difference in electrical potential between each pair of the selected detection lines. A capacitance computation circuit 6 performs computation using each of the detected potential difference values and the transformation matrix to derive differences in electrostatic capacitance between electrostatic capacitance at each intersection of one selected drive line with the selected detection lines and electrostatic capacitance at each intersection of the other selected drive line with the selected detection lines.

Description

  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, Patent Document 2, and Patent Document 3 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 among the plurality of first electrodes, and supplies a voltage having a higher potential than the reference voltage to one of the two selected first electrodes and supplies a reference voltage to the other To do. 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 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 (A−B).

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.

In the invention of Patent Document 3, a plurality of transmission electrodes corresponding to one of the two dimensions in the detection region, a reception electrode corresponding to the other dimension, and at least two of the transmission electrodes are periodically provided. A multi-line driving means for simultaneously applying an alternating voltage, a current measuring means, a computing means, and a control means are included.
The calculation means includes a linear calculation means for linearly calculating the current value measured by the current measurement means or the accumulated charge amount, and converting the current value into a value corresponding to the capacitance at each intersection of the transmission electrode and the reception electrode, and a linear calculation means It is comprised with the proximity calculation means which calculates | requires the approach determination or approach position of the object from an output to a detection area. The linear operation means includes storage means for storing the intermediate result of the calculation.

JP 2009-15490 A JP 2010-282539 A JP 2011-047774 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 realize a high-resolution touch sensor having a large number of electrodes. Noise generated when touching 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, but parasitic capacitance is canceled. Must have a large capacitance. Further, the invention described in Patent Document 2 is not sufficient in noise reduction.

According to the invention described in Patent Document 3, periodic AC signals are added to a plurality of drive lines, and linear calculation is performed after reception. However, only the drive electrodes are expected to improve S / N by multi-line drive, and the effect is Limited. In addition, there is no mechanism for extracting information on changes in capacitance due to touch.
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.

In order to solve the above problems and achieve the object of the present invention, the present invention is configured as follows.
According to a first aspect of the present invention, there is provided a touch sensor including a touch panel including a plurality of first lines and a plurality of second lines arranged to intersect the plurality of first lines via an insulating layer. A signal processing circuit, comprising a first drive terminal and a second drive terminal, a first detection terminal and a second detection terminal, wherein the first drive terminal and the first detection terminal A difference between the first capacitance connected between the second capacitance and the second capacitance connected between the second drive terminal and the first detection terminal is obtained as a first capacitance difference. , A third capacitance connected between the first drive terminal and the second detection terminal, and a fourth capacitance connected between the second drive terminal and the second detection terminal. The difference from the capacitance is obtained as a second capacitance difference, and the difference between the first capacitance difference and the second capacitance difference is defined as a third capacitance difference. Therefore, a capacitance measuring circuit that selects any one of the first capacitance difference, the second capacitance difference, and the third capacitance difference, converts the capacitance into a predetermined signal, and outputs the signal, and the plurality of capacitance measurement circuits. Each of the first line and the second line can be connected to the first drive terminal, the second drive terminal, the first detection terminal, the second detection terminal, and a predetermined potential. A selection circuit.

  According to a second invention, in the first invention, the first offset comprises: a first capacitor having a variable capacitance and having one terminal connected to the first detection terminal; and a first switch. A second offset adjustment circuit comprising: an adjustment circuit; a second capacitor having a variable capacitance and having one terminal connected to the second detection terminal; and a second switch. The first switch can be set so that the other terminal of the first capacitor is connected to either the first drive terminal or the second drive terminal, or neither is connected to the first drive terminal. The second switch can be set so that the other terminal of the second capacitor is connected to either the first drive terminal or the second drive terminal, or neither is connected.

  In a third aspect based on the second aspect, the selection circuit is selected each time a detection pattern is selected from a plurality of detection patterns determined in accordance with a predetermined conversion matrix. The plurality of first lines and the plurality of second lines are connected to the first drive terminal according to a detection pattern, and the plurality of first lines and the plurality of second lines are connected to the first drive terminal. And zero or more lines are connected to the second drive terminal, and at least one of the plurality of first lines and the plurality of second lines is connected to the first line. And zero or more lines among the plurality of first lines and the plurality of second lines are connected to the second detection terminal.

In a fourth aspect based on the third aspect, the first offset adjustment circuit is configured to minimize the first capacitance difference when the touch panel is not touched for each of the plurality of detection patterns. Calibration is performed in advance, and the second offset adjustment circuit is calibrated in advance so that the second capacitance difference when not touching is minimized.
According to a fifth invention, in the fourth invention, the calculation is performed based on each output signal of the capacitance measurement circuit corresponding to the plurality of detection patterns and the conversion matrix, and is connected to the first drive terminal. Capacitance at each intersection of a line and each line connected to the first detection terminal and the second detection terminal, and corresponding to the selected second drive terminal The apparatus further includes a capacitance calculating unit that calculates a capacitance of a difference between each line and a capacitance at each intersection between the first detection terminal and each line connected to the second detection terminal.

In a fourth aspect based on the fourth aspect, the calculation is performed based on each output signal of the capacitance measuring circuit corresponding to the plurality of detection patterns and the conversion matrix, and the plurality of first lines and the plurality of lines are calculated. And a capacitance calculating unit that calculates the capacitance at each intersection with the second line.
According to a seventh invention, in the fifth or sixth invention, after the capacitance calculation unit converts the output signal of the capacitance measurement circuit into a signal corresponding to a change in capacitance when the touch panel is touched, An operation is performed based on the converted signal and the conversion matrix.

The eighth invention is the invention according to any one of the fifth to seventh inventions, wherein the touch panel is not touched before performing the calculation based on the output signal of the capacitance measuring circuit and the conversion matrix. And an offset correction circuit for correcting the output signal so that the output of the capacitance measuring circuit becomes zero.
In a ninth aspect based on any one of the fifth to eighth aspects, the transformation matrix is 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 number of rows or the number of columns excluding a part of the row vector or column vector of the transformation matrix is set to the number of the plurality of first lines or the plurality of second lines. Based on the matched matrix, the capacity calculation unit uses a transposed matrix or a generalized inverse matrix of the matrix.

  In a tenth aspect based on any one of the fifth to eighth aspects, the conversion matrix uses a first conversion matrix and a second conversion matrix, and the first conversion matrix is used. And the second transformation matrix is a first transformation matrix having a size greater than or equal to the number of the plurality of first lines, or a second transformation matrix having a size greater than or equal to the number of the plurality of second lines. The plurality of detection patterns are predetermined based on the first conversion matrix and the second conversion matrix, and the size of the first conversion matrix is the plurality of first lines. The third transformation matrix excluding a part of the row vector or column vector of the first transformation matrix is used as the first transformation matrix, and the second transformation matrix Is a size that is greater than the number of the plurality of second lines. The second conversion matrix is determined in advance using the fourth conversion matrix excluding a part of the row vector or column vector of the second conversion matrix as the second conversion matrix, and the capacity calculation unit And the transposed matrices of the second transformation matrix or their generalized inverse matrices.

In an eleventh aspect based on any one of the third to tenth aspects, the transformation matrix is a Hadamard transformation matrix.
A twelfth invention is a touch sensor including a touch panel including a plurality of first lines and a plurality of second lines arranged to intersect the plurality of first lines via an insulating layer. A signal processing circuit having a first drive terminal, a second drive terminal, and a detection terminal, and a first capacitance connected between the first drive terminal and the detection terminal; A capacitance measuring circuit that obtains a capacitance difference of a difference between a second capacitance connected between the second drive terminal and the detection terminal, converts the obtained capacitance difference into a predetermined signal, and outputs the signal. And each of the plurality of first lines and second lines includes the first drive terminal, the second drive terminal, the detection terminal, and a selection circuit that can be connected to a predetermined potential. .

According to a thirteenth aspect, in the twelfth aspect, the present invention further includes an offset adjustment circuit including a capacitor having a variable capacitance and one terminal connected to the first detection terminal, and a switch, The other terminal of the capacitor can be connected to either the first drive terminal or the second drive terminal, or can be set not to be connected to either.
In a fourteenth aspect based on the thirteenth aspect, the selection circuit is selected each time one detection pattern is selected from a plurality of detection patterns determined in accordance with a predetermined conversion matrix. In accordance with the detection pattern, at least one line from the plurality of first lines is connected to the first drive terminal, and zero or more lines from the plurality of first lines are connected to the first drive terminal. And at least one line of the plurality of second lines is connected to the detection terminal.

In a fifteenth aspect based on the fourteenth aspect, the offset adjustment circuit calibrates the plurality of detection patterns in advance so that the capacitance difference is minimized when the touch panel is not touched. .
In a sixteenth aspect based on the fifteenth aspect, an operation is performed based on each output signal of the capacitance measuring circuit corresponding to the plurality of detection patterns and the conversion matrix, and the selected drive line and the selected line are selected. And a capacitance calculating unit that calculates the capacitance at each intersection with each detection line.

In a seventeenth aspect based on the sixteenth aspect, the capacitance calculation unit converts the output signal of the capacitance measurement circuit into a signal corresponding to a change in capacitance when the touch panel is touched, and An operation is performed based on the signal and the conversion matrix.
In an eighteenth aspect based on the sixteenth or seventeenth aspect, the output of the capacitance measuring circuit when the touch panel is not touched before performing the calculation based on the output signal of the capacitance measuring circuit and the conversion matrix. And an offset correction circuit for correcting the output signal so that becomes zero.

  In a nineteenth aspect based on any one of the sixteenth to eighteenth aspects, the transformation matrix is 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 number of rows or the number of columns excluding a part of the row vector or column vector of the transformation matrix is set to the number of the plurality of first lines or the plurality of second lines. Based on the matched matrix, the capacity calculation unit uses a transposed matrix or a generalized inverse matrix of the matrix.

In a twentieth aspect based on any one of the fourteenth to nineteenth aspects, the transformation matrix is a Hadamard transformation matrix.
According to a twenty-first aspect, in any one of the third to eleventh aspects and the fourteenth to twentieth aspects, the selection circuit includes the first drive terminal for each of the plurality of detection patterns. The line connected to the first drive terminal and the line connected to the second drive terminal are changed, and the line connected to the first drive terminal and the second drive terminal is changed to connect to the first detection terminal. The line and the line connected to the second detection terminal are changed.

  In a twenty-second aspect based on any one of the third to eleventh aspects and the fourteenth to twenty-first aspects, the selection circuit is a predetermined detection pattern of the plurality of detection patterns. The line selected as the line connected to the first drive terminal is changed to the connection to the first detection terminal, and the line connected to the second drive terminal is changed. The connection of the selected line to the second drive terminal is changed to the connection to the second detection terminal, and the line selected as the line to be connected to the first detection terminal is connected to the first detection terminal. The connection is changed to the connection to the first drive terminal, and the connection 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. To do.

According to a twenty-third aspect of the invention, in any one of the fifth to tenth aspects of the invention and the sixteenth to nineteenth aspects of the invention, the capacity calculation unit is a predetermined detection pattern among the plurality of detection patterns. The output signal of the capacitance measuring circuit is processed as 0.
According to a twenty-fourth aspect, in the touch sensor, the touch sensor signal processing circuit according to any one of the first to twenty-third aspects is provided.

  A twenty-fifth aspect of the invention is 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 a driving voltage output unit. A drive circuit having one output terminal and a second output terminal; a first operation for outputting a first voltage corresponding to an input voltage of the first input terminal; and an input voltage of the first input terminal. A voltage detection circuit that selectively performs a second operation of detecting and outputting a differential voltage between a first voltage according to the second voltage and a second voltage according to an input voltage of the second input terminal; A selective connection between a first line, the plurality of second lines, and a first output terminal or a second output terminal of the driving circuit; and the plurality of first lines and the plurality of first lines. 2 line and the first input terminal or the second input terminal of the voltage detection circuit A selection circuit for performing selective connection, a variable capacitance, and one terminal connected to the first input terminal of the voltage detection circuit and the other terminal connected to the first output terminal of the drive circuit or the first A first capacitor that can be connected to two output terminals, a variable capacity, one terminal being connected to a second input terminal of the voltage detection circuit, and the other terminal being a first capacitor of the drive circuit. A touch sensor signal processing method including an electrostatic capacity circuit having a second capacitor connectable to an output terminal or a second output terminal, wherein the computer determines the conversion matrix according to a predetermined conversion matrix. One detection pattern is selected from the plurality of detection patterns, and one or more of the plurality of first lines or the plurality of second lines are selected according to the selected detection pattern. In 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 operation of the selection circuit is controlled so that the first 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. And selecting one or more lines as a first detection line group from the plurality of first lines or the plurality of second lines, and the plurality of first lines or the plurality of lines. From the plurality of second lines, zero or more lines are selected as a second detection line group, the first detection line group is connected to a first input terminal of the voltage detection circuit, and the first 2 detection line groups are connected to the first voltage detection circuit. A second step of controlling the operation of the selection circuit so as to be connected to the second input terminal; a third step of setting one of the first operation and the second operation performed by the voltage detection circuit; Each capacitance of the first and second capacitors is set, and the other end of the first capacitor is not connected or connected to the first output terminal of the drive circuit or the second output terminal of the drive circuit; A fourth step of controlling the operation of the capacitance circuit so that the other end of the second capacitor is not connected or is connected to the first output terminal of the drive circuit or the second output terminal of the drive circuit; And 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 as to perform the set first operation or second operation. 5 steps and the voltage A sixth step of performing an operation based on the output signal of the output circuit and the conversion matrix, and calculating the capacitance of each intersection of the plurality of first lines and the plurality of second lines, respectively. Run.

  In a twenty-sixth aspect based on the twenty-fifth aspect, in the first step, the plurality of first lines and the plurality of second lines are connected to the first drive line group for each of the plurality of detection patterns. And changing the selection as the second drive line group, and in the second step, the plurality of first lines and the plurality of second lines are changed according to the change in the first step. The selection as the first detection line group and the second detection line group is changed.

  In a twenty-seventh aspect based on the twenty-fifth or twenty-sixth aspect, when the detection pattern is a predetermined detection pattern among the plurality of detection patterns, in the first step, the drive circuit of the selected first drive line group is selected. The connection to the first output terminal is changed to the connection to the first input terminal of the voltage detection circuit, and the connection of the selected second drive line group to the second output terminal of the drive circuit is changed to the connection to the second output terminal of the drive 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 second input terminal of the voltage detection circuit. The connection to the first output terminal is changed, and the connection of the selected 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. To do.

In a twenty-eighth aspect of the present invention, in any one of the twenty-fifth to twenty-seventh aspects, when the detection pattern is a predetermined detection pattern among the plurality of detection patterns, the processes from the first step to the fifth step are performed. Omitted, in the sixth step, the output signal of the voltage detection circuit is processed as 0.
In a twenty-ninth aspect based on any one of the twenty-fifth to the twenty-eighth aspects, the transformation matrix is 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 number of rows or the number of columns excluding a part of the row vector or column vector of the transformation matrix is set to the number of the plurality of first lines or the plurality of second lines. Predetermined based on the matched matrix, each of the first step and the second step uses the plurality of predetermined detection patterns, and in the sixth step, the transposed matrix of the matrix Or use generalized inverse matrix.

  According to a thirtieth aspect, in any one of the twenty-fifth to twenty-eighth aspects, the transformation matrix uses a first transformation matrix and a second transformation matrix, and the first transformation matrix. And the second transformation matrix is a first transformation matrix having a size greater than or equal to the number of the plurality of first lines, or a second transformation matrix having a size greater than or equal to the number of the plurality of second lines. The plurality of detection patterns are predetermined based on the first conversion matrix and the second conversion matrix, and the size of the first conversion matrix is the plurality of first lines. The third transformation matrix excluding a part of the row vector or column vector of the first transformation matrix is used as the first transformation matrix, and the second transformation matrix A size larger than the number of the plurality of second lines. In this case, 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 in advance, and the first step and the second step are performed. In each process of the step, a plurality of detection patterns defined by the first conversion matrix and the second conversion matrix are used, and in the process of the sixth step, the first conversion matrix and the second conversion matrix are used. Use each transpose of the transformation matrix or each generalized inverse of them.

In a thirty-first aspect, in any one of the twenty-fifth to thirtieth aspects, the transformation matrix is a Hadamard transformation matrix.
A thirty-second invention causes a computer to execute each step in the touch sensor signal processing method according to any one of the twenty-fifth to thirty-first inventions in a touch sensor signal processing program.

ADVANTAGE OF THE INVENTION According to this invention, the signal processing circuit of the touch sensor which employ | adopted new signal processing regarding the signal processing of a touch sensor can be provided.
In addition, according to the present invention, the signal processing of the touch panel can be significantly improved as compared with the prior art.
In addition, even if the number of panel electrodes does not have Hadamard conversion, a signal processing circuit for a touch sensor having a higher S / N ratio can be provided by using a larger Hadamard conversion.

  Further, even when measurement is performed by linearly coupling the electrodes, it is possible to prevent malfunction due to variation in the parasitic capacitance value of the touch sensor due to environmental variation such as temperature variation.

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 circuit 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. It is a figure which shows the timing of the operation | movement of the states 1-4 of a drive circuit and a voltage detection circuit, and the ON / OFF state of the switch at that time. It is the figure which put together the relationship between the operation | movement of the states 1-4 of a drive circuit and a voltage detection circuit, and the ON / OFF state of the switch corresponding to this. It is explanatory drawing explaining operation | movement of the drive circuit and voltage detection circuit of 1st Embodiment. It is a figure which shows the connection relationship of the detection patterns 1-4 of 1st Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the connection relationship of the detection patterns 5-8 of 1st Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a block diagram which shows the structure of the principal part of the modification 1 of 1st Embodiment. It is a block diagram which shows the structure of the principal part of the modification 2 of 1st Embodiment. 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 figure which shows the connection relation of the detection patterns 1-4 of 2nd Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the connection relationship of the detection patterns 5-8 of 2nd Embodiment, and the drive circuit and voltage detection circuit corresponding to it, 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. It is a figure which shows the connection relation of the drive patterns 1-4 of 3rd Embodiment, the drive circuit corresponding to it, a voltage detection circuit, and each line. It is a figure which shows the drive patterns 5-8 of 3rd Embodiment, and the connection relationship of the drive circuit and voltage detection circuit corresponding to it, 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 an offset correction circuit. A baseline estimation circuit 13, a capacitance calculation circuit 6, a touch position detection circuit 7, a control circuit 8, an address generation circuit 9, a memory 10, a latch 11, and a capacitance circuit 12 for offset adjustment. It has.

  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. Further, 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. Therefore, the X lines X1 to X8 and the Y lines Y1 to Y8 are insulated from each other via the 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 the + side input terminal (detection terminal) 44 of the voltage detection circuit 4, The rest is connected to the negative input terminal (detection terminal) 45 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 line 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. Further, the output is switched by setting information from a latch 11 described later.

Here, the drive circuit 3 and the voltage detection circuit 4 constitute a capacitance measurement circuit, and more specifically, a differential capacitance-voltage conversion circuit.
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.
Since the output value of the AD conversion circuit 5 fluctuates when the baseline of the output of the voltage detection circuit 4 drifts (fluctuates) due to environmental fluctuation such as temperature change, the baseline estimation circuit 13 copes with this. To do.

  That is, the baseline estimation circuit 13 outputs the output voltage of the voltage detection circuit 4 when the touch panel 1 is not touched before performing the calculation based on the output voltage of the voltage detection circuit 4 and the conversion matrix, as will be described later. The output value of the AD conversion circuit 5 corresponding to the output voltage of the voltage detection circuit 4 when the touch panel 1 is not touched is estimated from the output value of the AD conversion circuit 5. Subtract the value and output it. In short, the baseline estimation circuit 13 corrects the output value of the AD conversion circuit 5 so that the output becomes zero when the touch panel 1 is not touched.

  As will be described later, the capacity calculation circuit 6 is based on each output voltage of the voltage detection circuit 4 that has been A / D converted by the A / D conversion circuit 5 and corrected by the baseline estimation circuit 13 and a predetermined conversion matrix. An operation is performed, and the change in capacitance at each intersection between one drive line selected by the selection circuit 2 and each detection line selected by the selection circuit 2 and the other drive selected by the selection circuit 2 Capacitance changes corresponding to differences between capacitance changes at the intersections between the lines and the detection lines selected by the selection circuit 2 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. When the capacitance circuit 12 is calibrated, in addition to the above-described control, the output of the A / D conversion circuit 5 is monitored and the address generation circuit 9, the memory 10, and the latch 11 are controlled as will be described later. Thus, the capacitance circuit 12 is indirectly controlled.

The address generation circuit 9 generates an address for reading setting data (described later) 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 later-described switch of the selection circuit 2 according to the detection procedure, switching control data for the switches SW 7 and SW 8 of the capacitance circuit 12, Capacitance setting data for capacitors CR1 and CR2 whose capacitances are variable, and output switching control data for the voltage detection circuit 4 are stored in advance.

The latch 11 controls on / off of a switch described later of the selection circuit 2, switching control of switches SW7 and SW8 of the capacitance circuit 12, capacitance setting control of the capacitors CR1 and CR2 whose capacitance is variable, and output of the voltage detection circuit 4. When switching control is performed, setting data read from the memory 10 is temporarily stored.
As shown in FIG. 1, the capacitance circuit 12 includes capacitors CR1 and CR2 for offset adjustment that can vary the capacitance values, and switches SW7 and SW8.

  One end side of the capacitor CR1 is connected to the input terminal 44 of the voltage detection circuit 4, and the other end side of the capacitor CR1 is connected to a common terminal (switching contact) of the switch SW7. The switch SW7 is a neutral single-pole double-throw switch, and one of the two contacts (fixed contact) is connected to the + side output terminal 33 of the drive circuit 3, and the other is the − side output terminal of the drive circuit 3. 34.

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 common terminal of the switch SW8. The switch SW8 is a neutral single-pole double-throw switch, and one of the two contacts is connected to the + side output terminal 33 of the drive circuit 3, and the other is connected to the − side output terminal 34 of the drive circuit 3. ing.
In the capacitance circuit 12 having such a configuration, every time the drive pattern is switched based on the setting information from the latch 11, the capacitance values of the offset adjustment capacitors CR1 and CR2 and the switches SW7 and SW8 are switched. Since the switches SW7 and SW8 are neutral single-pole double-throw switches, the switching contact is connected to the + side output terminal 33 of the drive circuit 3, connected to the-side output terminal 34, or neither is set to be connected. Is possible.

The capacitance values of the offset adjustment capacitors CR1 and CR2 and the settings of the switches SW7 and SW8 are calibrated in advance as described later for each drive pattern. The value determined by the calibration is stored in the memory 10 in association with the on / off control data of the switch described later of the selection circuit 2.
The offset adjustment capacitors CR1 and CR2 only need to be configured so that the capacitance can be varied by the control input. For example, the offset adjustment capacitors CR1 and CR2 are configured by a plurality of capacitors and switches having different sizes, and the on / off of the switch is controlled by the control input. May be configured to be variable. Further, a voltage-controlled variable capacitance element such as a varicap may be used.

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. -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, the decoders 24-5 to 24-8, and the capacitance circuit 12 The control signal line from the latch 11 to the capacitance circuit 12 and the output switching control line from the latch 11 to the voltage detection circuit 4 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 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 connection lines 25 to 29. It is.

For this reason, 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 units.
The switch SW11 is used for connection between the input terminal 44 of the voltage detection circuit 4 and one of the X lines X1 to X8 and the Y lines Y1 to Y8. The switch SW12 is used for connection between the input terminal 45 of the voltage detection circuit 4 and 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 for connection between the output terminal 34 of the drive circuit 3 and 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 SW <b> 11 to SW <b> 15 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, 3.3 V) to one end of the switch SW1, and applies a low-potential power supply voltage VSS to one end of the switch SW2. (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. Is provided with a subtracting circuit 43 that calculates the difference between the two, input terminals 44 and 45, an output selection control input terminal 46, and an output selection circuit 47 comprising a switch SW9.
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 OP2.

The output selection circuit 47 can select any of the output of the integration circuit 41, the output of the integration circuit 42, and the output of the subtraction circuit 43 according to a control signal input to the output selection control input terminal 46.
For this reason, when the output of the integration circuit 41 is selected, only the capacitance connected to the + input terminal 44 of the voltage detection circuit 4 is subjected to capacitance / voltage conversion (C / V conversion) and output to the output terminal Vout. When the output of the integration circuit 42 is selected, only the capacitance connected to the negative input terminal 45 of the voltage detection circuit 4 is C / V converted and output to the output terminal Vout. When the output of the subtraction circuit 43 is selected, the capacitance connected to the + input terminal 44 of the voltage detection circuit 4 is connected to the −input terminal 45 of the voltage detection circuit 4 from the voltage output after C / V conversion. The voltage obtained by C / V conversion of the obtained capacitance is subtracted and output.

Next, operations of the drive circuit 3 and the voltage detection circuit 4 will be described with reference to FIGS.
As shown in FIG. 5, the drive 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 similarly to 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 electrostatic capacitances formed at each intersection. The output selection circuit 47 is omitted because the output of the subtraction circuit 43 is selected.

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 as 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 the + side input terminal 44 of the voltage detection circuit 4, and the remainder of the X lines X1 to X8 is connected to the-side input terminal 45 of the voltage detection circuit 4.

9A to 9D and 10E to 10H show eight detection patterns 1 to 8 determined according to the Hadamard transformation matrix and X lines X1 to X8 according to these detection patterns. And the voltage detection circuit 4 are connected.
For example, in the case of the detection pattern 1 shown in FIG. 9A, the X lines X1 to X8 are connected to the + side input terminal 44 of the voltage detection circuit 4, and the-side input terminal 45 of the voltage detection circuit 4 is Are not connected, and the output selection circuit 47 selects the output of the integration circuit 41. The capacitance of the offset adjustment capacitor CR1 and the connection state of the switch SW7 are determined by calibration (calibration), and the switch SW8 is set to a neutral state in which neither is connected.

Note that the output selection circuit 47 selects the output of the integration circuit 41 only in the case of FIG. 9A, and in the case of FIGS. 9B to 9D and FIGS. 10E to 10H. The output of the subtraction circuit 43 is selected.
Similarly, the switch SW8 is set to the neutral state only in the case of FIG. 9A, the connection state of the switch SW7 and the capacitance value of the offset adjustment capacitor CR1 in the case of FIG. The connection states of the switches SW7 and SW8 and the capacitance values of the offset adjustment capacitors CR1 and CR2 in the cases (B) to (D) and FIGS. 10E to 10H are determined by calibration.

In the case of the detection pattern 2 shown in FIG. 9B, the X lines X1, X3, X5, X7 are connected to the + side input terminal 44 of the voltage detection circuit 4, and the X lines X2, X4, X6, X8 are connected. Is connected to the negative input terminal 45 of the voltage detection circuit 4.
9 and 10, reference characters C <b> 1 to C <b> 8 are capacitances formed at the intersections of the Y line Y <b> 2 and the X lines X <b> 1 to X <b> 8, and reference characters C <b> 9 to C <b> 16 are Y line Y <b> 1 and It is a capacitance formed at each intersection with the X lines X1 to X8. ΔCj is a change in the capacitance Cj when the touch panel is touched.
In the case of the detection pattern 1 shown in FIG. 9A, the output voltage D1 of the voltage detection circuit 4 is expressed by the following equation (1D).

  When the sign of the offset adjustment capacitor CR1 is +, the switch SW7 is connected to the + side output terminal of the drive circuit 3, and when-, the switch SW7 is connected to the − side output terminal of the drive circuit 3. When the touch panel is not touched, the sign and capacity of the offset adjustment capacitor CR11 are calibrated in advance so that D1 = VCOM.

  When Cj changes due to an environmental change such as a temperature change, the output value of the A / D conversion circuit 5 is estimated when the baseline estimation circuit 13 is not touching the touch panel, and the capacitance Cj changes due to the touch. It operates so that the minute ΔCj is output. When the baseline estimation circuit 13 operates correctly, the terms VCOM, CR11, and Cj in the equation (1D) are canceled, and an output like the equation (1D ′) is obtained.

  The output voltage Di according to the detection patterns shown in FIGS. 9 and 10 excluding FIG. 9A can be expressed by the following equation (1E).

  However, i = 2,. CR1i and CR2i are the set values of the offset adjustment capacitors CR1 and CR2 in the detection pattern i. When the sign is +, they are connected to the + side output terminal 33 of the drive circuit 3, and when-, they are connected to the drive circuit 3. It indicates that it is connected to the negative output terminal 34. The set values of the offset adjustment capacitors CR1 and CR2 generally have different values for each detection pattern i.

The CR1i code and magnitude are calibrated so that the output of the integration circuit 41 when not touched is VCOM, and the CR2i sign and magnitude is such that the output of the integration circuit 42 when not touched is VCOM. Calibrate in advance.
When Cj changes due to environmental changes such as temperature changes, the output value of the A / D conversion circuit 5 when the baseline estimation circuit 13 is not touching the touch panel is estimated, and the change in the capacitance Cj due to the touch is made. It operates so as to output ΔCj. When the baseline estimation circuit 13 operates correctly, the terms VCOM, CR1i, CR2i, and Cj in the equation (1E) are canceled and an output like the equation (1E ′) is obtained.

  In the equation (1E), Di (i = 1, 2,..., 8) is an output voltage (detection voltage) of the voltage detection circuit 4 obtained according to the eight detection patterns 1-8. Cj (j = 1, 2,..., 8) is a capacitance between the Y line Y2 and the X line Xj, and ΔCj is the amount of change when touched. Cj + 8 (j = 1, 2,..., 8) is a capacitance between the Y line Y1 and the X line Xj, and ΔCj is the amount of change when touched.

sij is an (i, j) component of the 8-row × 8-column Hadamard transform matrix expressed by the equation (2). In the detection pattern i, the X line Xj is connected to the + side input terminal 44 of the voltage detection circuit 4 when sij = + 1, and the X line Xj is connected to the − side input terminal 45 of the voltage detection circuit 4 when sij = −1. The
Also, the signs “+” and “−” at the intersections of the X axis and the Y axis in FIGS. 9 and 10 indicate that “+” is a coefficient of ΔCj (j = 1. “−” Means that the coefficient of ΔCj (j = 1... 16) in the formula (1E ′) is −1.

  Next, for each of the detection patterns 1 to 8 described above, 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 output voltages D1 to D8 of the voltage detection circuit 4 are 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 6. When the storage of the output voltages D1 to D8 is completed, the capacitance calculation circuit 6 determines the capacitance difference (ΔC1−ΔC9), (ΔC2) based on the stored output voltages D1 to D8 and the Hadamard transformation matrix that is the transformation matrix. −ΔC10)... (ΔC8−ΔC16) 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 on the basis of the change in the capacitance value calculated by the capacitance calculation circuit 6 (ΔC1-ΔC9), (ΔC2-ΔC10) (ΔC8-ΔC16). To do.
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 the voltage detection circuit 4 changes to the detection patterns 1 to 8 for each change. Accordingly, a 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, in the memory 10, 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 is provided for each predetermined drive pattern and detection pattern 1-8. Data for controlling on / off of SW15 are stored.

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 the necessary data by 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. Accordingly, 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. In addition, 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 unit 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, the X lines X1 to X4 are selected as the first detection lines, and the 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. Further, 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 arithmetic processing according to the first to eighth detection patterns to obtain the output voltages D1 to D8, respectively, and each of the output voltages D1 to D1. Differential amplification was performed when D8 was obtained. Therefore, noise can be reduced when the output voltages D1 to D8 are obtained, and 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 an offset adjustment capacitor in order to obtain the output voltages D1 to D8. Even if it is not necessary to provide a capacitor or it is necessary to provide a capacitor, a capacitor having a very small capacity is sufficient.
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, 12 rows × 12 columns, 16 rows × 16 columns, or the like can also be used. Also, a Hadamard transform matrix of a form other than the expression (2) can 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)
In the first embodiment, as shown in FIG. 1, a baseline estimation circuit 13 that corrects the output voltage of the voltage detection circuit 4 is provided after the AD conversion circuit 5. As shown in -1, the control circuit 8 is provided with the function of the baseline estimation circuit 13.

That is, in the first modification, a baseline estimation unit 82 is provided in the control circuit 8 in addition to the drive control unit 81, as shown in FIG. The baseline estimation unit 82 inputs (monitors) the output of the AD conversion circuit 5, and varies the capacitances of the offset adjustment capacitors CR1 and CR2 according to the input.
As a result, the baseline drift of the voltage detection circuit 4 due to environmental fluctuations can always be fed back to the offset adjustment capacitors CR1 and CR2 to cancel the drift.
In addition, about this modification 1, it can apply to each below-mentioned 2nd-4th embodiment.

(Modification 2 of the first embodiment)
In the second modification, as shown in FIG. 11-2, the control circuit 8 has the function of the baseline estimation circuit 13 of the first embodiment shown in FIG.
That is, in Modification 2, as shown in FIG. 11B, the control circuit 8 is provided with a baseline estimation unit 82A in addition to the drive control unit 81. The baseline estimation unit 82A inputs (monitors) the output voltage of the voltage detection circuit 4, and varies the capacitances of the offset adjustment capacitors CR1 and CR2 according to the input.
As a result, the baseline drift of the voltage detection circuit 4 due to environmental fluctuations can always be fed back to the offset adjustment capacitors CR1 and CR2 to cancel the drift.
This modification 2 can be applied to second to fourth embodiments described later.

(Modification 3 of the first embodiment)
In the first embodiment, as shown in FIG. 1, the baseline estimation circuit 13 for correcting the output voltage of the voltage detection circuit 4 is provided after the AD conversion circuit 5, but the baseline estimation circuit 13 is not necessarily provided. It is not necessary and may be omitted.
Note that such omission of the baseline estimation circuit 13 is the same in the second to fourth embodiments described later.

(Modification 4 of the first embodiment)
This modification 4 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.
In the fourth 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 eight 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. Each A / D-converted output voltage is converted by the baseline estimation circuit 13 into a change caused by the touch, and 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 determines the capacitance difference (ΔC1−ΔC9), (ΔC2) based on the stored output voltages D1 to D8 and the Hadamard transformation matrix that is the transformation matrix. −ΔC10)... (ΔC7−ΔC15) are calculated.
The arithmetic processing performed by the capacity calculation circuit 6 can be expressed by the following equation (3 ′).

However, the coefficient matrix appearing in the equation (3 ′) is an extraction of the left 7 rows × 8 columns of the 8-row × 8-column Hadamard transform matrix expressed by the equation (2), and the s _ij of the equation (1E) It is a transposed matrix and Moore-Penrose's generalized inverse matrix (scalar times).
Although the output voltage output from the voltage detection circuit 4 is eight and more than seven electrodes, since the coefficient matrix of the equation (3 ′) is a generalized inverse matrix, the obtained (ΔC1−ΔC9), ( ΔC2−ΔC10)... (ΔC7−ΔC15) is a least squares solution that satisfies the equation (1E). Therefore, the greater the number of output voltages of the voltage detection circuit 4, the better the S / N.
This modification 4 can be applied to the case where the coefficient matrix appearing in the expression (3 ′) is not the Hadamard transform part of the rows deleted, but the orthogonal transform and the orthogonal transform obtained by scalar multiplication and the deletion of some rows. It is.
The fourth modification can be applied to second and third embodiments described later.

(Modification 5 of the first embodiment)
In the first embodiment, as shown in FIGS. 9 and 10A to 10H, Y1 is connected to the negative terminal 34 of the drive circuit 3, Y2 is connected to the positive terminal 33 of the drive circuit 3, and X1 to X8 are The driving 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 in accordance with 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 the patterns including the pattern of FIG. 9A are detected with a differential configuration, resistance to common mode noise is improved.
This modification 5 can be applied to the modifications 1 to 4 of the first embodiment.

(Configuration of Second Embodiment)
FIG. 12 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. 12, 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 an offset correction circuit. A baseline estimation circuit 13, a capacitance calculation circuit 6A, a touch position detection circuit 7A, a control circuit 8, an address generation circuit 9, a memory 10, a latch 11, and a capacitance circuit 12 for offset adjustment. And. Note that the drive patterns stored in the memory 10 are different from those in the first embodiment.

Thus, the second embodiment is based on the configuration of the first embodiment shown in FIG. 1, and the capacitance calculation circuit 6 and the touch position detection circuit 7 shown in FIG. 6A is replaced with the touch position detection circuit 7A.
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.

(Operation of Second Embodiment)
Next, in the second embodiment, a case where the touch position of the touch panel 1 is detected will be described with reference to FIGS.
First, the selection circuit 2 selects one predetermined line as a drive line among the Y lines Y1 to Y8 of the touch panel 1 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 + side input terminal 44 of the voltage detection circuit 4, and the remainder of the X lines X1 to X8 is connected to the-side 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 X1 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 X1 to X8 are connected to the input terminal 44 of the voltage detection circuit 4. In the case of the detection pattern 2 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 voltages. Connected to the input terminal 45 of the detection circuit 4. The output selection circuit 47 of the voltage detection circuit 4 in FIGS. 13 and 14 is connected to the integration circuit 41 in the case of FIG. 13A, and is connected to the subtraction circuit 43 in all other cases.

Reference numerals C1 to C8 in FIGS. 13 and 14 denote 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 described above, 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 switch SW7 is connected to the negative output terminal 34 of the drive circuit 3, and the switch SW8 is in a neutral state in which neither is connected. The output selection circuit 47 of the voltage detection circuit 4 is connected to the integration circuit 41.
In the case of the detection patterns 2 to 8, the switches SW7 and SW8 are determined to be connected to either the + side output terminal 33 or the − side output terminal 34 of the drive circuit 3 by calibration. The output selection circuit 47 of the voltage detection circuit 4 is connected to the subtraction circuit 43.
Here, the calculation process in which the voltage detection circuit 4 detects eight potential differences in accordance with the detection patterns 1 to 8 can be expressed by the following equation (4).

  However, i = 1, 2,... Further, when i = 1, the capacitance value of the offset adjustment capacitor CR2 does not affect the output, so that CR2i = 0. ΔCj is the amount of change in Cj when touched. CR1i and CR2i are the set values of the offset adjustment capacitors CR1 and CR2 in the detection pattern i. When the sign is +, they are connected to the + side output terminal 33 of the drive circuit 3, and when-, they are connected to the drive circuit 3. It indicates that it is connected to the negative output terminal 34. The set values of the offset adjustment capacitors CR1 and CR2 generally have different values for each detection pattern i.

The CR1i code and magnitude are calibrated so that the output of the integration circuit 41 when not touched is VCOM, and the CR2i sign and magnitude is such that the output of the integration circuit 42 when not touched is VCOM. Calibrate.
When Cj changes due to an environmental change such as a temperature change, the output value of the A / D conversion circuit 5 is estimated when the baseline estimation circuit 13 is not touching the touch panel, and the capacitance Cj changes due to the touch. It operates so that the minute ΔCj is output. When the baseline estimation circuit 13 operates correctly, the terms CR1i, CR2i, Cj, and VCOM in the equation (4) are canceled, and only the change ΔCj of the capacitance when touched remains, and the equation (4 ′) The output is as follows.

  In the equation (4), Di (i = 1, 2,..., 8) is an output voltage (detection voltage) of the voltage detection circuit 4 obtained according to the eight detection patterns 1-8. Cj (j = 1, 2,..., 8) is a capacitance between the Y line Y1 and the X line Xj, and ΔCj is a change when the touch panel is touched. sij is an (i, j) component of the 8-row × 8-column Hadamard transform matrix expressed by the equation (2). In the detection pattern i, the X line Xj is connected to the + side input terminal 44 of the voltage detection circuit 4 when sij = + 1, and the X line Xj is connected to the − side input terminal 45 of the voltage detection circuit 4 when sij = −1. The

  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 capacitance calculation circuit 6A changes the capacitance when the touch panel is touched based on the stored output voltages D1 to D8 and the Hadamard transformation matrix that is a transformation matrix. Calculations for calculating ΔC1 to ΔC8 are performed.

  The arithmetic processing performed by the capacity calculation circuit 6A can be expressed by the following equation (5).

The touch position detection circuit 7A detects the touch position of the touch panel 1 based on the changes ΔC1 to ΔC8 caused by the touch of the capacitance 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 performs the arithmetic processing according to the eight detection patterns to obtain the output voltages D1 to D8, and obtains the output voltages D1 to D8. Differential amplification was performed. Therefore, noise can be reduced when the output voltages D1 to D8 are obtained, and S / N can be improved.
In the second embodiment, an Hadamard transformation matrix of 8 rows × 8 columns is used as shown in the equation (4). However, a Hadamard transform matrix such as 4 rows × 4 columns, 12 rows × 12 columns, 16 rows × 16 columns, or the like 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, the 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 a case where the finger | toe 100 exists in the vicinity of the electrostatic capacitances C1-C4, and the output voltage D5 of the voltage detection circuit 4 becomes D5 <0. (B) is a 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 whether it is in any vicinity.

(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.
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 the 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 / BR> J
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 2A, a drive circuit 3, a voltage detection circuit 4A, an A / D conversion circuit 5, and an offset correction circuit. A baseline estimation circuit 13, a capacitance calculation circuit 6A, a touch position detection circuit 7A, a control circuit 8A, an address generation circuit 9, a memory 10A, a latch 11A, and a capacitance circuit 12A. ing.

  As described above, the third embodiment is based on the configuration of the second embodiment shown in FIG. 12, and includes the selection circuit 2, the differential amplification type voltage detection circuit 4, the control circuit 8, the memory 10, and the latch 11 shown in FIG. And the capacitance circuit 12 are replaced with a selection circuit 2A, a single-type voltage detection circuit 4A, a control circuit 8A, a memory 10A, a latch 11A, and a capacitance circuit 12A as shown in FIG. .

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.
The selection circuit 2A is obtained by omitting the connection line 26 and the switch SW12 from the selection circuit 2 to the negative input terminal 45 of the voltage detection circuit 4.
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. This is the same function as when the switch SW9 of the output selection circuit 47 of the voltage detection circuit 4 of FIG. 4 is set so that the output of the integration circuit 41 is always selected to Vout, and therefore the input is performed instead of the voltage detection circuit 4A. The voltage detection circuit 4 to which only the terminal 44 is connected can also be used.

The memory 10A and the latch 11A have one signal line connected by the selection circuit 2A, and the capacitance circuit 12A has fewer offset adjustment capacitors CR2 and switches SW8 than the capacitance circuit 12. As the amount of information decreases, the bit width decreases.
As shown in FIG. 17, the electrostatic capacity circuit 12A includes an offset adjusting capacitor CR3 having a variable capacitance value and a switch SW20. One end of the capacitor CR3 is connected to the input terminal of the voltage detection circuit 4A, and the other end of the capacitor CR3 is connected to the common terminal of the switch SW20. The switch SW20 is a neutral single-pole double-throw switch, and one of the two contacts is connected to the + side output terminal 33 of the drive circuit 3 and the other is connected to the − side output terminal 34 of the drive circuit 3.

Each time the drive pattern is switched based on the setting information from the latch 11A, the capacitance value of the offset adjustment capacitor CR3 and the switch SW20 are switched. Since the switch SW20 is a neutral single-pole double-throw switch, it can be set to be connected to the + side terminal 33 of the drive circuit 3, connected to the-side terminal 34, or not connected to either.
The capacitance value of the offset adjustment capacitor CR3 and the setting of the switch SW20 are calibrated in advance as described later for each drive pattern. The value determined by the calibration is stored in the memory 10A in association with on / off control data of a switch described later of the selection circuit 2A. The configuration and calibration method of the offset adjustment capacitor CR3 are exactly the same as those of the offset adjustment capacitor CR1.

  The control circuit 8A controls the drive circuit 3, the voltage detection circuit 4A, the address generation circuit 9, and the latch 11A when detecting the touch position of the touch panel 1. Further, when calibrating the capacitance circuit 12A, in addition to the above-described control, the output of the A / D conversion circuit 5 is monitored, and the capacitance is controlled by controlling the address generation circuit 9, the memory 10A, and the latch 11A. The circuit 12A is indirectly controlled.

(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.
First, the selection circuit 2A selects one predetermined line as a detection line among the Y lines Y1 to Y8 of the touch panel 1 in accordance with 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).

Further, the selection circuit 2A, when one of eight predetermined driving patterns is selected according to a predetermined conversion matrix, the X lines X1 to X1 of the touch panel 1 are selected according to the selected driving pattern. A part of X8 is connected to the + side output terminal 33 of the drive circuit 3, and the remainder of the X lines X1 to X8 is connected to the-side output terminal 34 of the drive circuit 3.
FIGS. 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 X1 corresponding to these driving patterns 1 to 8, respectively. The connection state of X8 and the drive circuit 3 is shown.
For example, in the case of the drive pattern 1 shown in FIG. 18A, the X lines X1 to X8 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 + side output terminal 33 of the drive circuit 3, and the X lines X2, X4, X6, X8 is connected to the negative 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, the switches 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, the switches SW2 and SW3 are turned on, and the switch SW10 of the voltage detection circuit 4A is turned off.
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 following equation (4A).

  However, i = 1, 2,... CR3i is a set value of the offset adjustment capacitor CR3 in the detection pattern i. When the sign is +, it is connected to the + side output terminal 33 of the drive circuit 3, and when it is-, the − side output terminal of the drive circuit 3 is connected. 34 is connected. The set value of the offset adjustment capacitor CR3 generally has a different value for each detection pattern i.

The code and the size of CR3i are calibrated so that the output of the voltage detection circuit 4A when not touched is VCOM.
When Cj changes due to an environmental change such as a temperature change, the output value of the A / D conversion circuit 5 is estimated when the baseline estimation circuit 13 is not touching the touch panel, and the capacitance Cj changes due to the touch. It operates so that the minute ΔCj is output. When the baseline estimation circuit 13 operates correctly, the terms CR3i, Cj, and VCOM in the equation (4A) are canceled, and only the change ΔCj of the capacitance when the touch panel is touched remains, and the equation (4A ′) The output is as follows.

  In the equation (4A), Di (i = 1, 2,..., 8) is an output voltage (detection voltage) of the voltage detection circuit 4A obtained according to the eight detection patterns 1-8. Cj (j = 1, 2,..., 8) is a capacitance between the Y line Y1 and the X line Xj, and ΔCj is the amount of change when touched. sij is an (i, j) component of the 8-row × 8-column Hadamard transform matrix expressed by the equation (2). In the detection pattern i, the X line Xj is connected to the + side output terminal 33 of the drive circuit 3 when sij = + 1, and the X line Xj is connected to the − side output terminal 34 of the drive circuit 3 when sij = −1.

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 operations for calculating the capacitances C1 to C8 based on the stored output voltages D1 to D8 and the Hadamard transform matrix that is a conversion matrix. Do. The arithmetic processing performed by the capacity calculation circuit 6A can be expressed by the above equation (5).

The touch position detection circuit 7A detects the touch position of the touch panel 1 based on the capacitance changes ΔC1 to ΔC8 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. It is also possible to increase the scan rate by providing a plurality of voltage detection circuits 4A, A / D conversion circuits 5 and capacitance circuits 12A and operating them in parallel.
In the third embodiment, the offset adjustment capacitor CR3 shown in FIG. 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 (5). However, a Hadamard transform matrix such as 4 rows × 4 columns, 12 rows × 12 columns, 16 rows × 16 columns, or the like 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 2A 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 according to 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 8, 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. 12, and as shown in FIG. 20, the capacitance calculation circuit 6A and the touch position detection circuit 7A shown in FIG. This is replaced with the position detection circuit 7B.
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 memory 10 stores a pattern different from the first embodiment and the second embodiment.

(Operation of Fourth Embodiment)
Next, in the fourth embodiment, a case where the touch position of the touch panel 1 is detected 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 remaining 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 X1 to X8 is connected to the input terminal 45 of the voltage detection circuit 4.
FIG. 21 to FIG. 36 show the 64 conversion patterns determined according to the Hadamard conversion 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 the pattern 1 and the eight patterns 1 to 8. 23 and 24 show eight conversion patterns obtained by combining pattern 2 and eight patterns 1-8. 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 in which the pattern 4 and the eight patterns 1 to 8 are combined.

  29 and 30 show eight conversion patterns obtained by combining the pattern 5 and the 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 to 8. 35 and 36 show eight conversion patterns obtained by combining the pattern 8 and the eight patterns 1 to 8.

  In the example of FIGS. 21 to 36, the Y axis is connected to the drive circuit and the X axis is connected to the voltage detection circuit. Conversely, the X axis is connected to the drive circuit and the Y axis is connected to the voltage detection circuit. Also good. Further, it may be changed for each pattern whether the drive circuit and the voltage detection circuit are connected to the X axis or the Y axis. 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, the voltage detection circuit is made differential by exchanging the + terminal of the drive circuit and the + terminal of the voltage detection circuit, and exchanging the − terminal of the drive circuit and the − terminal of the voltage detection circuit. By changing to the configuration of FIG. 21, the voltage detection circuit having the differential configuration is used for all patterns except the pattern of FIG. 21A, and the S / N can be further improved. Further, even if the + terminal of the drive circuit and the + terminal of the voltage detection circuit, and the − terminal of the drive circuit and the − terminal of the voltage detection circuit 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 (5A).

However, m = 1, 2,..., 8 and n = 1, 2,.
21 to 36, the sign “+” at each intersection of the X axis and the Y axis in the drawings is s _mi s _nj = + 1, and the sign “−” is s _mi s _nj = −1. . s _mi is the (m, i) component of the 8-row × 8-column Hadamard transformation matrix represented by the equation (2), and s _nj is the 8-row × 8-column Hadamard transformation matrix represented by the equation (2). (N, j) component. When s _mi = + 1 in the pattern m × pattern n, the X line Xi is connected to the + side input terminal 44 of the voltage detection circuit 4. When s _mi = −1, the X line Xi is the − side of the voltage detection circuit 4. The Y line Yj is connected to the + side output terminal 33 of the drive circuit 3 when s _nj = + 1, and the Y line Yj is connected to the − side output terminal 34 of the drive circuit 3 when s _nj = −1. Connected to.

CR1mn and CR2mn are the set values of the offset adjustment capacitors CR1 and CR2 when the X-axis detection pattern is m and the Y-axis drive pattern is n. The sign and capacity value of CR1mn are determined by calibration so that the output of the integration circuit 41 when not touching the touch panel is VCOM, and the sign and capacity value of CR2mn is the output of the integration circuit 42 when not touching. Determined by calibration to be VCOM.
When the capacitance circuit 12 and the baseline estimation circuit 13 function correctly, the terms CR1mn, CR2mn, Cij, and VCOM in the equation (5A) are canceled, and only the change ΔCj of the capacitance when touched remains. The output is as shown in equation (5A ′).

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.
In the equation (5A), Dmn is the 64 output voltages (detected voltages) of the voltage detection circuit 4 obtained according to the 64 conversion patterns, and is an 8 × 8 matrix.
Further, in Expression (5A), Cij is 64 capacitances at each intersection of the X line Xi and the Y line Yj of the touch panel 1, and is an 8 × 8 matrix. ΔCij is the amount of change when touched.

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. Then, 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 the transformation matrix, each of the X line X1 to X8 and the Y line Y1 to Y8 of the touch panel 1 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 (6).

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 selection circuit 2 combines all the electrodes, and the voltage detection circuit 4 performs arithmetic processing according to the 64 conversion patterns to obtain 64 output voltages, respectively. Thus, differential amplification is performed when each output voltage is obtained. For this reason, noise can be reduced when each output voltage is obtained, and further, S / N can be greatly improved because ΔCij is obtained by linearly combining all of Dmn according to equation (6).

  In the fourth embodiment, as shown in the equations (6) and (7), an Hadamard transformation matrix of 8 rows × 8 columns is used for H and H ′. However, a Hadamard transform matrix such as 2 rows × 2 columns, 4 rows × 4 columns, 12 rows × 12 columns, 16 rows × 16 columns, or the like can also be used. It is also possible to use Hadamard transformation matrices of different sizes for H and H ′. Furthermore, a Hadamard transform matrix of a format different from the format represented by the equation (7) can 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 the 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.

  If the electrodes bundled by the above grouping are regarded as one electrode, the X line can be regarded as four panels and the Y line can be regarded as two panels. After that, similarly to the fourth embodiment, it is possible to create a drive / detection pattern applying the Hadamard transform of 4 rows × 4 columns to the X line and the Hadamard transform of 2 rows × 2 columns 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. 38 and 39 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. / D converted value is acquired.
Thereafter, since the X line is 4 groups in the capacity calculation circuit 6B, 4 rows × 4 columns Hadamard transformation is used, and since the Y line is 2 groups, 2 rows × 2 columns Hadamard transformation is used. Similar processing is performed.

As a result, the total amount of capacitance formed at the intersection of the X lines X1, X2 and Y lines Y1, Y2, Y3, Y4 due to the touch, X lines X1, X2 and Y lines Y5, Y6, The total amount of capacitance formed at the intersection of the X lines X3, X4 and the Y lines Y1, Y2, Y3, Y4, the amount of change due to the touch of the total capacitance formed at the intersection of Y7, Y8 And a change due to the touch of the total capacitance formed at the intersections of the X lines X3, X4 and the Y lines Y5, Y6, Y7, Y8, respectively. Furthermore, the change in the total capacitance formed at the intersection of the X lines X5, X6 and Y lines Y1, Y2, Y3, Y4 due to the touch, X lines X5, X6 and Y lines Y5, Y6, Y7 , Y8, the change in the total capacitance formed at the intersection of Y8, the total of the capacitance formed at the intersection of X lines X7, X8 and Y lines Y1, Y2, Y3, Y4. The change due to the touch, and the change due to the touch of the total capacitance formed at the intersections of the X lines X7 and X8 and the Y lines Y5, Y6, Y7, and Y8 are obtained.
As described above, Modification 1 of the fourth embodiment is convenient for operation in the low power consumption mode because the number of measurement points is smaller than that of the fourth embodiment. In addition, since the capacity change for each group can be increased as much 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.
The size of the Hadamard transformation matrix is selected by a multiple of 4 that is equal to or 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 transform matrix of 8, that is, 8 rows × 8 columns, is used as a 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 detection patterns, which are all combinations thereof, are used.
Assuming that the capacitance formed between the axis Xi and the axis Yj is Cij and the amount of change when touched is ΔCij, the relationship with the value appearing at the output Dmn of the voltage detection circuit 4 is the following equation (5B) become that way.

However, m = 1, 2,..., 8 and n = 1, 2,.
s _mi is the (m, i) component of the 8-row × 8-column Hadamard transform matrix expressed by equation (2), and s _nj ′ is the 12-row × 12-column Hadamard transform expressed by equation (8). This is the (n, j) component of the matrix. The capacitance values and signs of CR1mn and CR2mn are determined by calibration as in the fourth embodiment.
When the capacitance circuit 12 and the baseline estimation circuit 13 function correctly, the terms CR1mn, CR2mn, Cij, and VCOM in the equation (5B) are canceled, and only the change ΔCij in the capacitance when touched remains. The output is as shown in equation (5B ′).

The 96 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. Each A / D-converted output voltage is converted by the baseline estimation circuit 13 into a change caused by the touch and sequentially stored in the capacitance calculation circuit 6B. When the storage of the output voltage is completed, the capacity calculation circuit 6B, based on the stored output voltage and the Hadamard transformation matrix that is the transformation matrix, each of the X line X1 to X7 and the Y line Y1 to Y9 of the touch panel 1 An operation for calculating 63 capacitances at the intersection is performed.
The arithmetic processing performed by the capacity calculation circuit 6B can be expressed by the following equation (9).

However, H ^T is (10) which was extracted 8 rows × 7 columns left transposed matrix of the Hadamard transform matrix of 8 rows × 8 columns of the formula, (5B) equation s _mi transposed matrix and Moore・ Penrose's generalized inverse matrix (scalar multiple). H ′ is an extracted 12-row × 9-column left side of the 12-row × 12-column Hadamard transformation matrix expressed by the equation (11), and is a transposed matrix of s _nj ′ and a _Moore- Penrose's generalized inverse matrix (scalar times). The H ^T is obtained by transposing the matrix H.

The output voltage output from the voltage detection circuit 4 is 96, which is larger than the number of electrodes 63. However, since H ^T and H ′ in the equation (9) are generalized inverse matrices, the obtained Cij is (5B). It is a least squares solution that satisfies the equation. Therefore, the greater the number of output voltages of the voltage detection circuit 4, the better the S / N.
In the second modification, H and H ′ are obtained by deleting some rows or columns of the Hadamard transformation matrix, but not only the Hadamard transformation matrix but also a part of the scalar transformation of the orthogonal transformation matrix and the orthogonal transformation matrix. It can also be applied to a matrix with rows or columns deleted.

  The touch position detection circuit 7B detects the touch position of the touch panel 1 based on the amount of change caused by the touch of the 63 capacitances calculated by the capacitance calculation circuit 6B.

(Fifth embodiment)
As shown in FIG. 1, the first embodiment includes a touch panel 1, a selection circuit 2, a drive circuit 3, a voltage detection circuit 4, an A / D conversion circuit 5, a baseline estimation circuit 13, a capacitance calculation circuit 6, and a touch position detection. A circuit 7, a control circuit 8, an address generation circuit 9, a memory 10, a latch 11, and a capacitance circuit 12 are provided. However, the baseline estimation circuit 13, 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, the functions of the baseline estimation circuit 13, the capacity calculation circuit 6, the touch position detection circuit 7, the control circuit 8 and the like shown in FIG. 1 are replaced with a computer (not shown).
The computer controls operations of the selection circuit 2, the drive circuit 3, the voltage detection circuit 4, the capacitance circuit 12, and the like, and performs calculation processing of the capacitance calculation circuit 6 and the touch position detection circuit 7.
For this reason, in the fifth embodiment, as shown in FIG. 39, procedures (programs) for various processes such as various predetermined controls and calculations are stored in advance in the memory 10 of FIG. 1, for example. Therefore, the computer performs various processes such as control and calculation.

Next, with reference to FIG. 1 and FIG. 39, 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, the voltage detection circuit 4, and the capacitance circuit 12 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 as the start address.

In step S2, control data corresponding to the drive and detection patterns stored in the set start address of the 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, among the Y lines Y1 to Y8 of the touch panel 1, a predetermined line 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 switch SW9 of the voltage detection circuit 4 is set based on the control data. With this setting, the output of the integration circuit 41 or the subtraction circuit 43 is set as the output of the voltage detection circuit 4.
In step S5, the switches SW7 and SW8 of the capacitance circuit 12 are set based on the control data, and the capacitance values of the offset adjustment capacitors CR1 and CR2 are set.

In step S6, the operation of the drive circuit 3 and the voltage detection circuit 4 is set to “state 1” based on the control data (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 S7, and when this standby is completed, the process proceeds to the next step S8.

In step S8, the operation of the drive circuit 3 and the voltage detection circuit 4 is set to “state 2” based on the control data (see FIG. 5). After this setting, in step S9, the process waits for a predetermined time, and this standby is completed.
Through a series of processes in steps S6 to S9, the voltage detection circuit 4 performs an operation according to the setting in step S4.

In step S10, an A / D conversion value output from the A / D conversion circuit 5 is acquired.
In step S11, a baseline is estimated based on the acquired A / D conversion value. This corresponds to the function of the baseline estimation circuit 13 in FIG.
In step S12, the A / D conversion value with the corrected baseline is stored.
In step S13, 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 and the process returns to step S2, and a series of processes of steps S2 to S13 are performed. On the other hand, if it is an end address (YES), the process proceeds to step S15.

In step S15, the capacitance difference is calculated by performing Hadamard inverse transformation based on the A / D conversion value in which the baseline stored in step S12 is corrected. This calculation corresponds to the function of the capacity calculation circuit 6 of FIG.
In step S16, the touch position is detected based on the capacitance difference calculated in step S15. This detection corresponds to the function of the touch position detection circuit 7 in FIG.

In step S17, the coordinates of the touch position detected in step S16 are output.
As described above, in the fifth embodiment, the functions of the baseline estimation circuit 13, the capacity calculation circuit 6, the touch position detection circuit 7, the control circuit 8, and the like shown in FIG. 1 are replaced with a computer.
However, in the second embodiment of FIG. 12, the functions of the baseline estimation circuit 13, the capacity calculation circuit 6A, the touch position detection circuit 7A, the control circuit 8, and the like may be replaced with a computer.

In the third embodiment of FIG. 16, the functions of the baseline estimation circuit 13, the capacity calculation circuit 6A, the touch position detection circuit 7A, the control circuit 8A, and the like may be replaced with a computer.
Furthermore, in the fourth embodiment of FIG. 20, the functions of the baseline estimation circuit 13, the capacity calculation circuit 6B, the touch position detection circuit 7B, the control circuit 8, and the like may be replaced with a computer.

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

  The signal processing circuit of the touch sensor of the present invention can be applied to a touch sensor and can also be applied 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 ... Control circuit 9 ... Address generation circuit 10, 10A ... Memory 11, 11A ... Latch 12, 12A ... Capacitance circuit 13 ... Baseline estimation circuits 21-1 to 21-8, 22-1 to 22-8, switch units 23-1 to 23-8, 24-1 to 24-8, decoders 25 to 29,. Connection lines SW1 to SW6 ... Switches SW7, SW8, SW20 ... Neutral single pole double throw switches SW11 to SW15 ... Switches

Claims (32)

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 a first drive terminal and a second detection terminal connected between the first drive terminal and the first detection terminal. A difference between a first capacitance and a second capacitance connected between the second drive terminal and the first detection terminal is obtained as a first capacitance difference, and the first drive terminal And a third capacitance connected between the second detection terminal and a fourth capacitance connected between the second drive terminal and the second detection terminal. Obtained as a second capacity difference, and obtained a difference between the first capacity difference and the second capacity difference as a third capacity difference, and obtained the first capacity difference, the second capacity difference, and the third capacity difference. A capacitance measuring circuit that selects and converts any one of the capacitance differences into a predetermined signal;
Each of the plurality of first lines and second lines can be connected to the first drive terminal, the second drive terminal, the first detection terminal, the second detection terminal, and a predetermined potential. A selection circuit which is
A signal processing circuit for a touch sensor, comprising: A first offset adjustment circuit comprising: a first capacitor having a variable capacitance and one terminal connected to the first detection terminal; and a first switch;
A second offset adjustment circuit including a second capacitor having a variable capacitance and one terminal connected to the second detection terminal; and a second switch;
The first switch can be set so that the other terminal of the first capacitor is connected to either the first drive terminal or the second drive terminal, or neither is connected.
The second switch can be set so that the other terminal of the second capacitor is connected to either the first drive terminal or the second drive terminal, or neither is connected. The signal processing circuit of the touch sensor according to claim 1. The selection circuit includes:
Each time one detection pattern is selected from among a plurality of detection patterns determined in accordance with a predetermined conversion matrix, the plurality of first lines and the plurality of lines are selected in accordance with the selected detection pattern. At least one of the second lines is connected to the first drive terminal, and zero or more lines of the plurality of first lines and the plurality of second lines are connected to the second line. To at least one of the plurality of first lines and the plurality of second lines to the first detection terminal, and the plurality of first lines and the plurality of lines. The signal processing circuit of the touch sensor according to claim 2, wherein zero or more lines are connected to the second detection terminal from among the second lines. The first offset adjustment circuit is calibrated in advance so that the first capacitance difference is minimized when the touch panel is not touched for each of the plurality of detection patterns.
4. The signal processing circuit of the touch sensor according to claim 3, wherein the second offset adjustment circuit is calibrated in advance so that the second capacitance difference when not touching is minimized.   An operation is performed based on each output signal of the capacitance measurement circuit corresponding to the plurality of detection patterns and the conversion matrix, and a line connected to the first drive terminal, the first detection terminal, and the second Capacitance at each intersection with each line connected to the detection terminal, and a corresponding line connected to the selected second drive terminal, the first detection terminal, and the second The touch sensor signal according to claim 4, further comprising a capacitance calculation unit that calculates a capacitance of a difference from a capacitance at each intersection with each line connected to the detection terminal. Processing circuit.   An operation is performed based on each output signal of the capacitance measurement circuit corresponding to the plurality of detection patterns and the conversion matrix, and static electricity at each intersection of the plurality of first lines and the plurality of second lines is calculated. The signal processing circuit of the touch sensor according to claim 4, further comprising a capacitance calculating unit that calculates each of the electric capacities.   The capacitance calculation unit converts the output signal of the capacitance measurement circuit into a signal corresponding to a change in capacitance when the touch panel is touched, and then performs an operation based on the converted signal and the conversion matrix. 7. The signal processing circuit of the touch sensor according to claim 5, wherein the signal processing circuit is a touch sensor.   An offset correction circuit that corrects the output signal so that the output of the capacitance measurement circuit is zero when the touch panel is not touched before performing an operation based on the output signal of the capacitance measurement circuit and the conversion matrix. The signal processing circuit of the touch sensor according to claim 5, further comprising: 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 circuit according to claim 5, wherein the capacitance calculation unit uses a transposed matrix or a generalized inverse matrix of the matrix. 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 detection patterns are predetermined based on the first transformation matrix and the second transformation matrix, and the size of the first transformation matrix is larger than the number of the plurality of first lines. In some cases, a third transformation matrix excluding a part of the row vector or 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 plurality of transformation matrices. When the size is equal to or larger than the number of the second lines, the fourth transformation matrix excluding a part of the row vector or the column vector of the second transformation matrix is used as the second transformation matrix to determine in advance. ,
The capacity calculation unit uses each transposed matrix of the first transformation matrix and the second transformation matrix or each generalized inverse matrix thereof. A signal processing circuit of the touch sensor according to claim 1.   The touch sensor signal processing circuit according to claim 3, wherein the transformation matrix is a Hadamard transformation matrix. 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, a second drive terminal, and a detection terminal, connected between the first drive terminal and the detection terminal, and the second drive terminal A capacitance measurement circuit that obtains a capacitance difference of a difference between the first capacitance and a second capacitance connected between the detection terminals, converts the obtained capacitance difference into a predetermined signal, and outputs the predetermined signal;
A selection circuit capable of connecting each of the plurality of first lines and second lines to the first drive terminal, the second drive terminal, the detection terminal, and a predetermined potential;
A signal processing circuit for a touch sensor, comprising: An offset adjustment circuit comprising a capacitor having a variable capacity and one terminal connected to the first detection terminal, and a switch;
The switch can be set so that the other terminal of the capacitor is connected to either the first drive terminal or the second drive terminal or not connected to either of the first drive terminal and the second drive terminal. 12. A signal processing circuit of the touch sensor according to 12. 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. At least one line is connected to the first drive terminal, zero or more lines are connected to the second drive terminal from the plurality of first lines, and the plurality of second lines are connected to each other. 14. The touch sensor signal processing circuit according to claim 13, wherein at least one line is connected to the detection terminal.   The touch sensor according to claim 14, wherein the offset adjustment circuit is calibrated in advance so that the capacitance difference when the touch panel is not touched is minimized with respect to each of the plurality of detection patterns. Signal processing circuit.   An operation is performed based on each output signal of the capacitance measurement circuit corresponding to the plurality of detection patterns and the conversion matrix, and electrostatic at each intersection of the selected drive line and each selected detection line. The touch sensor signal processing circuit according to claim 15, further comprising a capacitance calculation unit that calculates each of the capacitances.   The capacitance calculation unit converts the output signal of the capacitance measurement circuit into a signal corresponding to a change in capacitance when the touch panel is touched, and then performs an operation based on the converted signal and the conversion matrix. The touch sensor signal processing circuit according to claim 16.   An offset correction circuit that corrects the output signal so that the output of the capacitance measurement circuit is zero when the touch panel is not touched before performing an operation based on the output signal of the capacitance measurement circuit and the conversion matrix. The signal processing circuit of the touch sensor according to claim 16 or 17, further comprising: 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 circuit according to claim 16, wherein the capacitance calculation unit uses a transposed matrix or a generalized inverse matrix of the matrix.   20. The touch sensor signal processing circuit according to claim 14, wherein the transformation matrix is a Hadamard transformation matrix. The selection circuit includes:
For each of the plurality of detection 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 3 to 11 and claims 14 to 20. The selection circuit includes:
When the predetermined detection pattern among the plurality of detection patterns,
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 line to the second drive terminal is changed to the connection to the second detection terminal,
The connection to the first detection terminal of the line selected as the line connected to the first detection terminal is changed to the connection to the first drive terminal and selected as the line to be connected to the second detection terminal. Any one of claims 3 to 11, and 14 to 21, wherein the connection of the line to the second detection terminal is changed to the connection to the second drive terminal. 2. A signal processing circuit of the touch sensor according to item 1. The capacity calculation unit
20. The process of claim 5, wherein the output signal of the capacitance measurement circuit is set to 0 when the detection pattern is a predetermined detection pattern among the plurality of detection patterns. The signal processing circuit of the touch sensor according to any one of the above.   24. A touch sensor comprising the signal processing circuit of the touch sensor according to any one of claims 1 to 23. 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 first operation for outputting a first voltage corresponding to the input voltage of the first input terminal, a first voltage corresponding to the input voltage of the first input terminal, and an input voltage of the second input terminal. A voltage detection circuit that selectively performs a second operation of detecting and outputting a differential voltage from the corresponding second voltage;
Selective connection between the plurality of first lines, the plurality of second lines, and the first output terminal or the second output terminal of the drive circuit; the plurality of first lines; A selection circuit for performing selective connection between a plurality of second lines and a first input terminal or a second input terminal of the voltage detection circuit;
A first having a variable capacity, one terminal connected to the first input terminal of the voltage detection circuit and the other terminal freely connectable to the first output terminal or the second output terminal of the drive circuit. And a capacitor having a variable capacitance and having one terminal connected to the second input terminal of the voltage detection circuit and the other terminal connected to the first output terminal or the second output terminal of the drive circuit. A capacitance circuit having a free second capacitor;
A signal processing method for a touch sensor including:
Computer
One detection pattern is selected from a plurality of detection patterns determined according to a predetermined transformation matrix, and the plurality of first lines or the plurality of second patterns is selected according to the selected detection pattern. One or more lines are selected as the first drive line group from among the lines, or in addition to the first drive line group, zero or more lines different from the first drive line group are selected. Selected as the second drive line group, the first 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. A first step of controlling the operation of the selection circuit,
One or more lines are selected as a first detection line group from the plurality of first lines or the plurality of second lines, and the plurality of first lines or the plurality of second lines are selected. 0 or more lines are selected as a second detection line group, the first detection line group is connected to a first input terminal of the voltage detection circuit, and the second detection line group is A second step of controlling the operation of the selection circuit to be connected to a second input terminal of the voltage detection circuit;
A third step of setting one of a first operation and a second operation performed by the voltage detection circuit;
Each capacitance of the first and second capacitors is set, and the other end of the first capacitor is not connected or connected to the first output terminal of the drive circuit or the second output terminal of the drive circuit; A fourth step of controlling the operation of the capacitance circuit so that the other end of the second capacitor is not connected or is connected to the first output terminal of the drive circuit or the second output terminal of the drive circuit; When,
A fifth 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 as to perform the set first operation or second operation. When,
A sixth step of performing an operation based on the output signal of the voltage detection circuit and the conversion matrix, and calculating capacitances at respective intersections of the plurality of first lines and the plurality of second lines, respectively; ,
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 detection 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. 26. The touch sensor signal processing method according to claim 25, wherein selection is changed. When the predetermined detection pattern among the plurality of detection 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 connection of the second detection line group to the second input terminal of the voltage detection circuit is changed to a connection to the second output terminal of the drive circuit. Touch sensor signal processing method. When the predetermined detection pattern among the plurality of detection patterns,
The processing from the first step to the fifth step is omitted, and the output signal of the voltage detection circuit is processed as 0 in the sixth step. The touch sensor signal processing method according to claim 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
In each process of the first step and the second step, the plurality of predetermined detection patterns are used,
29. The touch sensor signal processing method according to claim 25, wherein a transpose matrix or a generalized inverse matrix of the matrix is used in the process of the sixth 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 detection patterns are predetermined based on the first transformation matrix and the second transformation matrix, and the size of the first transformation matrix is larger than the number of the plurality of first lines. In some cases, a third transformation matrix excluding a part of the row vector or 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 plurality of transformation matrices. When the size is equal to or larger than the number of the second lines, the fourth transformation matrix excluding a part of the row vector or the column vector of the second transformation matrix is used as the second transformation matrix to determine in advance. ,
In each process of the first step and the second step, a plurality of detection patterns defined by the first transformation matrix and the second transformation matrix are used,
The process of the sixth step uses each transposed matrix of the first transformation matrix and the second transformation matrix or each generalized inverse matrix thereof. The signal processing method of the touch sensor according to any one of the above.   31. The touch sensor signal processing method according to claim 25, wherein the transformation matrix is a Hadamard transformation matrix.   32. A touch sensor signal processing program causing a computer to execute each step in the touch sensor signal processing method according to claim 25.

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