JP2000172446A - Touch panel interface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel interface which properly and accurately detect a contact position while lightening the load on a system to which a touch panel is applied. SOLUTION: A touch panel device 1 converts an analog output voltage which is outputted by the touch panel 2 and corresponds to a depression coordinate position by an A/D converter 4 of an interface 3 into a digital signal and outputs it to an intermediate value selection part 7, and delays the signal by one cycle of a clock pulse CK1 by a data register 5 and a data register 6 respectively and outputs the delayed signal to the intermediate value selection part 7. The intermediate value selection part 7 selects and outputs a digital signal having an intermediate value among three digital signals inputted from the A/D converter 4, data register 5, and data register 6 to an output register 8, which outputs the digital signal from the intermediate value selection part 7 as a coordinate position signal Out1 to a system. An unnecessary coordinate position shift due to noise is reduced and a slow coordinate position shift caused by the integration of an analog voltage can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a touch panel interface, and more particularly, to a touch panel interface for appropriately and accurately detecting a contact position while reducing a load on a system to which the touch panel is applied.

[0002]

2. Description of the Related Art Recently, in an electronic information processing apparatus such as a personal computer, a word processor, an electronic organizer, and a portable telephone, a touch panel is superimposed on a surface of a display device to facilitate an input operation. 2. Description of the Related Art A touch panel has been developed that allows a user to touch a touch panel corresponding to a displayed content to perform an instruction, data selection, character input, and the like corresponding to the displayed content.

[0003] Such a conventional touch panel is usually
An LCD (Liquid Crystal Display) with a touch panel overlaid and used as a display screen
By touching a position on the touch panel corresponding to a command, a command corresponding to display content, data selection, character input, and the like can be performed.

[0004] As a touch panel, generally,
A resistive touch panel is used, and outputs a voltage signal corresponding to a touch position. The touch panel interface performs A / D conversion of the voltage signal output from the touch panel, and outputs the signal to the system of the electronic information processing apparatus as a coordinate position signal of the X coordinate and the Y coordinate on the display screen.

[0005] As described above, the touch panel is a device for transmitting a user's intention to a system such as a personal computer, and its processing is required to be quick. Flows and the processing load of the system software is large.

On the other hand, in order to confirm the intention input from the touch panel by looking at the reaction of the display panel and the like, the touch panel process responding to the user pressing the panel includes:
Quickness is required.

A touch panel is often used in combination with a surface lighting device such as a backlight, and unstable data may be generated due to noise from the backlight. Conventionally, various proposals have been made for the problem of noise in such a touch panel (see Japanese Patent Application Laid-Open No. 9-128146). It is removed by integrating the analog voltage before the D conversion.

[0008]

However, in the conventional touch panel interface, since the analog voltage output from the touch panel is integrated before A / D conversion, effective data is notified to the system after the touch panel is pressed. In addition, there is a problem that the data of the touch panel is slowly changed by integration, and there is a problem in that the data of the touch panel is appropriately and accurately detected.

In the touch panel, the contact area with the finger has a certain area, and the contact area between the finger and the touch panel fluctuates due to the pressing force when the finger is pressed. There is a problem that the coordinate position also changes minutely.

When the system responds each time such unstable data is generated or the coordinate position changes,
There is a problem that a load is imposed on the processing of the system and a correct response to the user is delayed.

Therefore, the present invention according to claim 1 performs A / D conversion of the output voltage of the touch panel that outputs analog voltage values corresponding to the X coordinate and the Y coordinate of the contact position, and converts the digital value to the contact position. When outputting as a coordinate position signal, the digital value is replaced with a digital value of an intermediate value among consecutive odd-numbered digital values including the latest digital value, and output as a coordinate position signal. In addition to reducing the unnecessary coordinate position change due to noise without integrating the analog voltage as in the past,
Suppressing slow changes in coordinate position caused by integrating the analog voltage to eliminate noise, reducing the processing load on the system, improving responsiveness, and detecting the exact contact position. It aims to provide a touch panel interface that can be used.

According to a second aspect of the present invention, the digital value of the current intermediate value is output as a coordinate position signal only when the digital value of the current intermediate value is different from the digital value of the previous intermediate value. Provided is a touch panel interface capable of further reducing the amount of data to be notified to the system, further reducing the processing load on the system, further improving the responsiveness, and detecting an accurate contact position. It is an object.

According to a third aspect of the present invention, a digital value of an intermediate value is obtained for each of the X coordinate and the Y coordinate of the contact position, and the digital value of the intermediate value is compared with the digital value of the previous intermediate value. Only when the digital value of the current intermediate value is different from the digital value of the previous intermediate value, the amount of data to be notified to the system by outputting the digital value of the current intermediate value as a coordinate position signal. It is an object of the present invention to provide a touch panel interface capable of further reducing the processing load of the system, further improving the responsiveness, and detecting a more accurate contact position. .

[0014]

According to a first aspect of the present invention, there is provided a touch panel interface comprising: an X coordinate of a contact position;
A touch panel interface that A / D converts the output voltage of the touch panel that outputs an analog voltage value corresponding to coordinates and outputs the digital value as a coordinate position signal indicating the contact position; The above object is achieved by replacing a value with a digital value of an intermediate value among consecutive odd-numbered digital values including the latest digital value and outputting the digital value after the replacement as a coordinate position signal. ing.

According to the above arrangement, the X coordinate of the contact position and the Y coordinate
When the output voltage of the touch panel that outputs an analog voltage value corresponding to the coordinates is A / D converted and the digital value is output as a coordinate position signal indicating the contact position, the digital value is converted to the latest digital value. It replaces with the digital value of the intermediate value among the consecutive odd-numbered digital values including and outputs as the coordinate position signal, so that unnecessary coordinate position change due to noise can be prevented without integrating the analog voltage as in the past. In addition to being able to reduce the noise, it is possible to suppress a gradual change in coordinate position caused by integrating an analog voltage for noise removal, thereby reducing the processing load on the system and improving the responsiveness. In addition, an accurate contact position can be detected.

In this case, for example, as described in claim 2, the touch panel interface compares the digital value of the intermediate value with the digital value of the previous intermediate value, and compares the digital value of the current intermediate value. Only when the value differs from the digital value of the previous intermediate value, the digital value of the current intermediate value may be output as the coordinate position signal.

According to the above configuration, the digital value of the current intermediate value is output as the coordinate position signal only when the digital value of the current intermediate value is different from the digital value of the previous intermediate value. The amount of data to be notified can be further reduced, the processing load on the system can be further reduced, the responsiveness can be further improved, and an accurate contact position can be detected.

Further, for example, the touch panel interface includes a digital value of the intermediate value of the digital value obtained by A / D converting an analog voltage value corresponding to the X coordinate of the touch position. Each of the intermediate digital values obtained by A / D conversion of the analog voltage values corresponding to the Y coordinate and the analog voltage value is compared with the digital value of the previous intermediate value to determine which of the X coordinate and the Y coordinate. Only when the digital value of the current intermediate value differs from the digital value of the previous intermediate value, the digital value of the current intermediate value may be output as the coordinate position signal.

According to the above arrangement, the X coordinate of the contact position and the Y coordinate
Find the intermediate digital value for each of the coordinates,
Compared to the digital value of the previous intermediate value, the current intermediate value only when the digital value of the current intermediate value differs from the digital value of the previous intermediate value in either the X coordinate or the Y coordinate. Is output as a coordinate position signal, the amount of data to be notified to the system can be further reduced, the processing load on the system can be further reduced, and the responsiveness can be further improved. A more accurate contact position can be detected.

[0020]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 3 show a first embodiment of a touch panel interface according to the present invention.
1 is a circuit configuration diagram of a touch panel device 1 to which a first embodiment of a touch panel interface of the present invention is applied.

In FIG. 1, the touch panel device 1 includes a touch panel 2 and an interface 3. The interface 3 includes an A / D converter 4, data registers 5, 6, an intermediate value selection unit 7, an output register 8, and the like. And outputs a detected digital coordinate position signal to a system (not shown) of an electronic information processing apparatus such as a personal computer. A predetermined clock pulse CK1 is input from the system to the A / D converter 4, the data registers 5, 6 and the output register 8.

As the touch panel 2, a normal touch panel is used, and an analog voltage signal corresponding to the pressed X and Y coordinate positions is output to the A / D converter 4.

The A / D converter 4 converts an analog voltage signal input from the touch panel 2 into a digital signal in synchronization with a clock pulse CK1 input from the system, and converts the analog signal into a data register 5 and an intermediate value selector. 7 to the A input.

The data register 5 stores the digital signal input from the A / D converter 4 in synchronization with the clock pulse CK1 input from the system, sets the stored digital signal as an output, and stores the digital signal in the data register. 6 and the B input of the intermediate value selection unit 7. That is,
The data register 5 delays the digital signal output from the A / D converter 4 by one cycle of the clock pulse CK1, and outputs the delayed digital signal to the data register 6 and the intermediate value selector 7.

The data register 6 stores the digital signal input from the data register 5 in synchronization with the clock pulse CK1 input from the system, sets the stored digital signal as an output, and stores the digital signal as an output. To the C input. That is, the data register 6
Delays the digital signal output from the data register 5 by one cycle of the clock pulse CK1 and outputs it to the intermediate value selection unit 7.

The intermediate value selection section 7 has an A input, a B input and a C input.
A digital signal having an intermediate value between the values of the three odd digital signals input to the three inputs is selected and output from the Y output to the output register 8. That is, the intermediate value selection unit 7 selects a digital signal having an intermediate value among the digital signals output from the A / D converter 4, the data register 5, and the data register 6, and outputs the digital signal to the output register 8.

The output register 8 stores the digital signal input from the intermediate value selector 7 in synchronization with the clock pulse CK1, and outputs the stored digital signal to the system as a coordinate position signal Out1.

The system takes in the coordinate position signal Out1 output from the output register 6 in synchronization with the clock pulse CK1 as a signal of the coordinate position of the touch panel 2.

Next, the operation of the present embodiment will be described. The touch panel device 1 adopts, as a detection signal of the touch panel 2, a digital signal having an intermediate value between digital signals obtained by digitally converting an analog voltage signal output from the touch panel 2 by one period of the clock pulse CK1. The feature is that noise is appropriately removed without integrating an analog voltage signal.

That is, the touch panel device 1 converts the analog voltage signal corresponding to the depressed coordinate position output from the touch panel 2 into a digital signal by the A / D converter 4 and outputs the digital signal to the intermediate value selection unit 7. , And the digital signal converted by the A / D converter 4 is delayed by the data register 5 and the data register 6 by one cycle of the clock pulse CK1 and output to the intermediate value selection unit 7.

The touch panel device 1 includes an intermediate value selection unit 7
A digital signal having an intermediate value is selected from three odd digital signals delayed by one cycle of the clock pulse CK1 input from the A / D converter 4, the data register 5, and the data register 6. , And outputs the digital signal input from the intermediate value selection unit 7 to the system as a coordinate position signal Out1 in synchronization with the clock pulse CK1.

Accordingly, an output value obtained by integrating the analog voltage output of the touch panel 2 by a conventional method to remove noise is represented by a broken line in FIG. When the digital signal is converted by the A / D converter 4 as shown by the solid line in FIG. 2, as can be seen from FIG. A digital signal indicating an abnormal value is included.

However, the touch panel device 1 of the present embodiment converts a digital signal having an intermediate value between three consecutive digital signals including the latest digital signal among digital signals obtained by digitally converting the analog voltage output of the touch panel 2. This is adopted as the coordinate position signal Out1.

Therefore, as shown by the solid line in FIG. 3, isolated noise can be effectively removed. Further, since the analog voltage signal is not integrated as in the prior art, the noise is reduced. In this case, it is possible to suppress a gradual change in output as shown by a broken line, thereby reducing the processing load on the system.

As described above, in the touch panel device 1 of the present embodiment, the A / D converter 4 converts the analog output voltage corresponding to the X coordinate and the Y coordinate of the touch position of the touch panel 2 into an A / D signal.
When performing D-conversion and outputting the digital value as a coordinate position signal indicating the contact position, the digital value is converted to the A / D converter 4 of the interface 3, the data register 5,
6. The intermediate value selector 7 and the output register 8 replace the digital value of the odd number (three times) including the latest digital value with the digital value of the intermediate value and output it as the coordinate position signal Out1. ing.

Therefore, unnecessary coordinate position change due to noise can be reduced without integrating the analog voltage as in the related art, and the slow coordinate position generated by integrating the analog voltage for noise removal can be reduced. The change can be suppressed, the processing load on the system can be reduced, the responsiveness can be improved, and the accurate contact position can be detected.

FIGS. 4 and 5 are diagrams to which the second embodiment of the touch panel interface according to the present invention is applied. In this embodiment, the digital value of the intermediate value of this time and the digital value of the intermediate value of the previous time are used. Only when the digital values are different, the digital value of the current intermediate value is output as the coordinate position signal.

The present embodiment is applied to a touch panel device similar to the touch panel device of the first embodiment, and in the description of the present embodiment, the first touch panel device will be described.
Components similar to those of the first embodiment will be described using the same reference numerals used in the description of the first embodiment.

FIG. 4 is a circuit block diagram of the comparison processing circuit section 11 included in the interface of the touch panel device 10 to which the touch panel interface of the present invention is applied. The touch panel device 10 of the present embodiment is the same as the first embodiment. A comparison processing circuit unit 11 for comparing the output of the output register 6 is added to the interface 3 of the touch panel device 1 according to the first embodiment.

Referring to FIG. 4, the comparison processing circuit section 11 includes a data register 12, a comparator 13, and a pulse generator 14.

The data register 12 receives the coordinate position signal Out1 output from the output register 6 of the touch panel device 1 shown in FIG. 1, and the clock input terminal of the data register 12 receives the output of the pulse generator 14. Is done.

The comparator 13 receives the coordinate position signal Out1 output from the output register 6 of the touch panel device 1 shown in FIG. 1 at its a input, and receives the output of the data register 12 at its b input. The comparator 13 compares the a input and the b input, that is, compares the coordinate position signal Out1 with the output of the data register 12, and determines whether the output Y is true or false depending on whether the a input and the b input are equal or not equal. Is output to the pulse generator 14.

The pulse generator 14 receives a true or false value from the comparator 13 and a clock pulse CK1 from a system (not shown). The pulse generator 14 outputs a false or false value from the comparator 13. When it changes to true, 1
A pulse (clock pulse) CK2 of a clock cycle is output to the system and the data register 12.

Then, the data register 12 is set to be one more than the clock pulse CK1 input from the pulse generator 14.
The coordinate position signal Out1 input from the output register 6 is held and output to the comparator 13 based on the clock pulse CK2 delayed by the period.

The touch panel device 10 according to the present embodiment
In the first embodiment, a comparator determines whether there is a difference between adjacent intermediate value digital signals including the latest digital signal, among digital signals having intermediate values of three consecutive digital signals. 13, when there is a difference between the digital signals of adjacent intermediate values, a clock pulse CK2 is output to the system, and the system outputs the clock pulse CK2.
Based on K2, the digital signal output from the output register 6, which is a digital signal having the intermediate value, is converted to a coordinate position signal Ou.
Acquired as t1.

Therefore, as shown in FIG.
An analog voltage output of the touch panel 2 is integrated by a conventional method to remove noise, and an output value is represented by a broken line in FIG. 2. The analog voltage signal of the touch panel 2 is converted by the A / D converter 4. Assuming that the digital conversion is represented as shown by a solid line in FIG. 2, the touch panel device 10 of the present embodiment outputs three consecutive digital signals among the digital signals obtained by digitally converting the analog voltage output of the touch panel 2. If there is a difference between successive intermediate value digital signals among the intermediate value digital signals, the intermediate value digital signal is converted to the coordinate position signal Out.
It is adopted as 2. That is, only the digital signal at the position indicated by the arrow in FIG.
Has been adopted as. As a result, as shown by the solid line in FIG. 5, isolated noise can be more effectively removed, and since the analog voltage signal is not integrated unlike the conventional case, it is shown by the broken line in FIG. Such a slow output change can be suppressed, and the processing load on the system can be further reduced.

As described above, the touch panel device 10 of the present embodiment sets the current intermediate digital value to the coordinate position only when the digital value of the current intermediate value is different from the digital value of the previous intermediate value. The signal is output as a signal Out2.

Therefore, the amount of data to be notified to the system can be further reduced, the processing load on the system can be further reduced, the responsiveness can be further improved, and the accurate contact position can be detected. it can.

FIG. 6 is a diagram to which a third embodiment of the touch panel interface according to the present invention is applied. In the present embodiment, the digital value of the intermediate value of the present time in either the X coordinate or the Y coordinate is used. Only when the digital value of the intermediate value is different from that of the previous intermediate value, the digital value of the current intermediate value is output as the coordinate position signal.

Note that the present embodiment is applied to a touch panel device similar to the touch panel device of the first embodiment, and in the description of the present embodiment, the first touch panel device will be described.
Components similar to those of the first embodiment will be described using the same reference numerals used in the description of the first embodiment.

FIG. 6 is a circuit block diagram of the comparison processing circuit section 21 included in the interface of the touch panel device 20 to which the touch panel interface of the present invention is applied. The touch panel device 20 of the present embodiment is the same as the first embodiment. The comparison processing circuit unit 21 for comparing the output of the output register 6 is added to the interface 3 of the touch panel device 1 according to the first embodiment.

In FIG. 6, when the same number of interfaces 3 of the first embodiment are arranged in the same configuration on both the X-axis and the Y-axis, the comparison processing circuit 21 outputs the output registers 6 of each interface 3. Output digital signal O
ut1a and 1b are compared, and data registers 22, 2
3. Comparators 224 and 25 and a pulse generator 26 are provided.

The digital signal Out1a output from the output register 6 of the interface 3 for the X axis of the touch panel device 1 shown in FIG. 1 is input to the data register 22, and the clock input terminal of the data register 22 generates a pulse. The clock pulse CK3 output from the detector 26 is input.

The data register 23 has an interface 3 for the Y axis of the touch panel device 1 shown in FIG.
The digital signal Out1b output from the output register 6 is input to the clock input terminal of the data register 23, and the clock pulse C output from the pulse generator 26 is output to the clock input terminal of the data register 23.
K3 is input.

The comparator 24 receives the digital signal Out1a output from the output register 6 of the interface 3 for the X-axis of the touch panel device 1 shown in FIG. Output is input. The comparator 24 compares the a input and the b input, that is, compares the digital signal Out1a for the X-axis with the output of the data register 22, and determines whether the a input and the b input are equal or not equal, from the output Y. A true or false value is output to the a input of the pulse generator 26.

The digital signal Out1b output from the output register 6 of the interface 3 for the Y-axis of the touch panel device 1 shown in FIG. Output is input. The comparator 25 compares the a-input and the b-input, that is, compares the Y-axis digital signal Out1b with the output of the data register 23, and determines whether the a-input and the b-input are equal or unequal. A true or false value is output to the b input of the pulse generator 26.

The pulse generator 26 receives true or false values from its comparators 24 and 25 at its a and b inputs, respectively, and outputs a clock pulse C from the system.
When K1 is input and the pulse generator 26 changes the output of either of the comparators 24 and 25 from false to true, 1
A pulse (clock pulse) CK3 having a clock cycle is output to the system and the data register 22 and the data register 23.

The data registers 22 and 23 are output registers for the X-axis and the Y-axis, respectively, based on the clock pulse CK3 delayed by one cycle from the clock pulse CK1 input from the pulse generator 26. 6, the digital signal Out1a and the digital signal O
ut1b is held and output to the comparators 24 and 25.

The touch panel device 20 of the present embodiment
In the first embodiment, the comparators 24 and 25 determine whether or not a difference occurs between adjacent intermediate values among the intermediate values of the digital signal values consecutive three times on either the X axis or the Y axis. When it is detected that there is a difference between the digital signals of adjacent intermediate values on either the X-axis or the Y-axis, a clock pulse CK3 is output to the system, and based on the clock pulse CK3, the system outputs the clock pulse CK3. X which is a digital signal of an intermediate value
Digital signal Out1 output from the axis output register 6
a as a coordinate position signal Out3a, and a digital signal Out1b output from the Y-axis output data register 6.
As the coordinate position signal Out3b.

As described above, the touch panel device 20 of the present embodiment obtains an intermediate digital value for each of the X coordinate and the Y coordinate of the contact position, compares the digital value with the previous intermediate digital value, Only when the digital value of the current intermediate value differs from the digital value of the previous intermediate value in either the X coordinate or the Y coordinate, the digital value of the current intermediate value is output as the coordinate position signals Out3a and Out3b. .

Therefore, the amount of data to be notified to the system can be further reduced, the processing load on the system can be further reduced, the responsiveness can be further improved, and a more accurate contact position can be detected. can do.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, the noise removal processing is performed by adopting an intermediate value of three consecutive digital values as the odd digital value including the latest digital value. The odd-numbered digital value including the latest digital value is not limited to three consecutive times, but may be appropriately selected as long as the number of times that noise removal can be appropriately performed, such as five or seven times. it can.

[0065]

According to the touch panel interface according to the first aspect of the present invention, the output voltage of the touch panel that outputs analog voltage values corresponding to the X coordinate and the Y coordinate of the touch position is A / D-converted. When outputting a digital value as a coordinate position signal indicating the contact position, the digital value is replaced with a digital value of an intermediate value among consecutive odd-numbered digital values including the latest digital value, and the coordinate position signal is output. As a result, unnecessary coordinate position change due to noise can be reduced without integrating the analog voltage as in the related art, and a slow coordinate position generated by integrating the analog voltage for noise elimination. Changes can be suppressed, processing load on the system can be reduced, responsiveness can be improved, and accurate contact positions can be detected. It can be.

According to the touch panel interface of the present invention, only when the digital value of the current intermediate value differs from the digital value of the previous intermediate value, the digital value of the current intermediate value is converted to the coordinate position signal. Output, the amount of data to be notified to the system is further reduced,
The processing load on the system can be further reduced, the responsiveness can be further improved, and an accurate contact position can be detected.

According to the third aspect of the present invention, the digital value of the intermediate value is obtained for each of the X coordinate and the Y coordinate of the contact position, and the digital value of the intermediate value is obtained by comparing the digital value of the previous intermediate value. Only when the digital value of the current intermediate value differs from the digital value of the previous intermediate value in either the coordinate or the Y coordinate, the digital value of the current intermediate value is output as a coordinate position signal. The amount of data to be notified can be further reduced, the processing load on the system can be further reduced, the responsiveness can be further improved, and the contact position can be detected more accurately.

[Brief description of the drawings]

FIG. 1 shows a first example of a touch panel interface according to the present invention.
FIG. 3 is a circuit block diagram of a touch panel device to which the embodiment is applied.

FIG. 2 is a diagram showing, with time, an analog voltage value obtained by integrating a voltage value output from the touch panel of FIG. 1 by a conventional technique and a digital value obtained by digital conversion.

FIG. 3 is a diagram showing a digital value obtained by performing a noise removal process on the digital output of FIG. 2 using the touch panel interface of FIG. 1 together with an analog voltage value over time.

FIG. 4 shows a second example of the touch panel interface of the present invention.
FIG. 10 is a circuit block diagram of a comparison processing circuit unit of the touch panel interface to which the embodiment of the present invention is applied.

FIG. 5 is a diagram showing, with arrows, digital values over time and their changing points by the touch panel interface of FIG. 4;

FIG. 6 shows a third example of the touch panel interface according to the present invention.
FIG. 10 is a circuit block diagram of a comparison processing circuit unit of the touch panel interface to which the embodiment of the present invention is applied.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 touch panel device 2 touch panel 3 interface 4 A / D converter 5, 6 data register 7 intermediate value selection unit 8 output register 10 touch panel device 11 comparison processing circuit unit 12 data register 13 comparator 14 pulse generator 20 touch panel device 21 comparison process Circuit part 22, 23 Data register 24, 25 Comparator 26 Pulse generator

Claims (3)

[Claims] 1. A / D conversion of an output voltage of a touch panel that outputs an analog voltage value corresponding to an X coordinate and a Y coordinate of a contact position, and outputs the digital value as a coordinate position signal indicating the contact position. In the touch panel interface, the digital value obtained by the A / D conversion is replaced with a digital value of an intermediate value among consecutive odd-numbered digital values including the latest digital value, and the digital value after the replacement is set at the coordinate position. Touch panel interface characterized by output as a signal. 2. The touch panel interface according to claim 1, wherein the digital value of the intermediate value is compared with a digital value of a previous intermediate value, and a digital value of a current intermediate value is different from a digital value of a previous intermediate value. 2. The touch panel interface according to claim 1, wherein a digital value of a current intermediate value is output as the coordinate position signal only in the case. 3. The touch panel interface according to claim 1, wherein the analog voltage value corresponding to the X coordinate of the touch position is A / A.
The digital value of the intermediate value of the D-converted digital value and Y
Each of the intermediate digital values of the digital values obtained by A / D conversion of the analog voltage values corresponding to the coordinates is compared with the previous intermediate digital value, and either the X coordinate or the Y coordinate is used. 2. The touch panel according to claim 1, wherein the digital value of the current intermediate value is output as the coordinate position signal only when the digital value of the current intermediate value is different from the digital value of the previous intermediate value. Interface.