JP2002049467A - Noise processing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently execute the noise processing of data obtained from a touch panel. SOLUTION: Digital data from the touch panel are successively shifted and inputted to buffers 0, 1, 2 connected like a pipeline. Data stored in the buffers 0, 2 are mutually subtracted by a subtractor 10 and the subtracted value is compared with a threshold by a comparator 14 to judge whether a difference between adjacent data is within a prescribed value or not. On the other hand, the adjacent data are mutually added by an adder 12 and an average value is obtained from the added value by a 1/2 circuit 18. A combination circuit 16 controls multiplexers 24x, 24y in accordance with the compared result of the comparator 14 and selects a suitable average value on the basis of the compared result of the difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a noise processing circuit for removing noise in position information detected from a touch panel.

[0002]

2. Description of the Related Art Conventionally, there has been known a touch panel which detects a touch of an operator's finger or the like and takes in information.
Used in various devices. In particular, portable devices,
In a vehicle-mounted device or the like, there are not enough places provided with buttons, a keyboard, and the like, and a keyboard or the like is difficult to use for an unfamiliar person with an input means used by many people. For this reason, a touch panel is disposed on the front of the display, and various information is input by operating the touch panel with respect to displaying buttons on the display. For example,
Touch panels are widely used in ATMs of banks, car navigation devices, portable information terminals, and the like. In a portable information terminal, a touch panel is also used for inputting handwritten characters and the like. In particular, when trying to use the Internet, etc. with a personal digital assistant,
If there is a touch panel, various inputs can be easily performed.

There are various methods such as an optical type and a resistance value detecting type for such a patch panel. Basically, the X and Y coordinates of a touched position on the panel are detected and output.
For example, in the resistance value detection method, a conductor film for taking out is arranged separately on the resistor film, and the conductor film contacts the resistor film in a touched portion. Thereby, the resistance value from one end of the resistor film to the contact point is detected. And the X direction and Y
By detecting the resistance value in the direction, the X coordinate and the Y coordinate of the touch point on the touch panel can be detected.

Here, the resistance value is detected as an analog current value or voltage value. Therefore, usually, after converting this analog value into digital data, the analog value is input to a microcomputer, and various data processing is performed to detect a touch point.

[0005]

Here, the position detection of such a touch panel involves more noise due to erroneous detection as compared with a normal button operation or the like. Therefore, the microcomputer performs various kinds of processing such as filtering to detect the position.

However, if special processing is performed on the input signal from the touch panel for the input signal, the load on the processing of the software of the microcomputer is increased, and a rapid processing may not be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a noise processing circuit that can efficiently perform noise processing on a detection signal from a touch panel.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a noise processing circuit for removing noise in digital data of position information detected from a touch panel.
A plurality of storage means for sequentially taking in the position information output from the / D converter, a subtractor for calculating a difference between the two position information taken in the storage means, and two positions taken in the storage means Selecting means for selecting one of at least two additional values obtained from the adder based on at least two difference values obtained from the adder for calculating an additional value for performing information averaging processing; And these are constituted by hardware.

As described above, since the circuit for selecting the added value based on the subtraction result is configured by hardware, it is possible to easily obtain an output from which noise has been removed. Therefore, efficient processing can be performed by reducing the load on the software in the subsequent stage.

The position information output from the A / D converter includes an X coordinate value and a Y coordinate value, which are sequentially output. There are six storage means and three X coordinate values. And the subtractor calculates two differences from two adjacent X coordinate values, and
The adder calculates two differences from two adjacent Y coordinate values. The adder calculates two addition values from two adjacent X coordinate values, and calculates two addition values from two adjacent Y coordinate values. Calculating, the selecting means may output one addition value for the X coordinate value and one addition value for the Y coordinate value based on the two differences for the X coordinate value and the Y coordinate value, respectively. It is suitable.

With such a circuit, it is possible to easily obtain an output from which noise on coordinate values has been removed.

The position information output from the A / D converter includes an X coordinate value and a Y coordinate value, which are sequentially output. There are three storage means and two X coordinate values. Value and one Y coordinate value or one X coordinate value and two Y coordinate values, and the subtractor stores 2
At the timing when one X coordinate value and one Y coordinate value are stored, a difference between the X coordinate values is calculated, and 2
The difference between the Y coordinate values is calculated at a timing at which one Y coordinate value and one X coordinate value are stored, and the adder calculates
At the timing when two X coordinate values and one Y coordinate value are stored in the storage means, an addition value for the X coordinate value is calculated, and two Y coordinate values and one X coordinate value are stored in the storage means. At a given time, an addition value is calculated for the Y coordinate value, and the selecting means calculates one addition value for the X coordinate value and a Y value for the Y coordinate value based on the two differences between the X coordinate value and the Y coordinate value. It is preferable to output one addition value of.

Preferably, the three storage means are connected in a pipeline, and one storage means takes in new data and shifts the storage contents sequentially to the next storage means.

With such a circuit, it is possible to perform processing on six input data by using three storage means, and it is possible to reduce the circuit scale and perform effective processing.

[0015]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of the circuit of the embodiment. The touch panel has an X based on the touch of the panel
Analog signals for the resistance values (X, Y coordinate values) in the direction and the Y direction are sequentially output. This analog signal is A
The data is sampled at a predetermined sampling rate by the / D converter, converted into digital data for the X coordinate value and the Y coordinate value, and this digital data is alternately sequentially input.

This digital data is input to buffer 0. Buffer 1 is connected to this buffer 0,
Buffer 2 is connected to buffer 1 and buffers 0,
Data in the three buffers 1 and 2 are sequentially transferred. Therefore, since this data transfer is performed in synchronization with the data switching timing of the input digital data, the oldest data is stored in the buffer 2 and the newest data is stored in the buffer 0. It is preferable that such buffers 0, 1, and 2 are constituted by shift registers.

For example, if the coordinate values detected by the touch panel are (Xa, Ya), (Xb, Yb), (Xc, Yc), the input digital data is Xa, Ya, Xb, Yb,
xc and Yc are input in this order. Therefore, at the first timing, Xb, Ya, and Xa are stored in buffers 0, 1, and 2, respectively.
Are stored, and at the next timing, Yb, X
b and Ya will be stored. Then, new data is sequentially input to the buffer 0, and the data is shifted.

Then, the outputs of the buffers 0 and 2 are sequentially supplied to a subtractor 10 and an adder 12. First, at the first timing, Xa and Xb are supplied to the subtractor 10 and the adder 12, and at the next timing, Ya and Yb are supplied to the subtractor 10 and the adder 12, and new data is supplied and data is shifted. This is repeated every time.

That is, in the subtractor 10, the difference data (Xa-Xb), (Ya-Yb), (Xb-X
c) and (Yb-Yc) are sequentially calculated and output, and the adder 12
Then, the added data (Xa + Xb) and (Ya + Y
b), (Xb + Xc) and (Yb + Yc) are sequentially calculated and output.

The output of the subtractor 10 is supplied to a comparator 14. The comparator 14 sequentially compares the supplied difference data with a threshold value Xth for the X difference and Yth for the Y difference. This is because the coordinate values sequentially output from the touch panel should not be so large, and the comparator 14 sequentially checks whether the moving distance is within a predetermined threshold value and outputs the determination result.

The output of the comparator 14 is, for example, "1" if it is below the threshold value and "0" if it exceeds the threshold value. In this example, the flag corresponding to the four difference data
XaXb, YaYb, XbXc, and YbYc are each set to “1” or “0”.

This flag is supplied to the combination circuit 16. The combination circuit 16 determines which two are to be selected as an average value from the four supplied flags, based on a predetermined rule. For example, if the flag is XaXb = 0, XbXc = 1, the average value of (Xb + Xc) is selected. Otherwise, the average value of (Xa + Xb) is selected. If the flag is YaYb = 0, YbYc = 1, The average value of (Yb + Yc) is selected, and otherwise, the average value of (Ya + Yb) is selected. By this, the average value calculated earlier is normally calculated. However, if one set of differences is out of the predetermined range first and another set of differences is within the predetermined range, the average value calculated later is calculated. The decision is to choose a value.

On the other hand, the output of the adder 12 is a half circuit 1
8 and an operation of 行 わ is performed, and an average value is output for each addition value. That is, this 1/2 circuit 18
From (Xa + Xb) / 2, (Ya + Yb) / 2, (X
b + Xc) / 2 and (Yb + Yc) / 2 are sequentially calculated and output.

As for this output, the output for X is taken into the register 20x, and the output for Y is taken into the register 20y. Further, registers 22x and 22y are connected to the registers 20x and 20y, and the data is sequentially shifted. Therefore, at a predetermined timing, the register 2
0x has (Xb + Xc) / 2, and register 22x has
(Xa + Xb) / 2, (Yb + Y) is stored in the register 20y.
c) / 2, (Ya + Yb) / 2 is stored in the register 22y.

The registers 20x and 22x are connected to the registers 20y and 2x via a multiplexer (MUX) 24x.
2y is connected to an output register 26 via a multiplexer (MUX) 24y.
24y is switched by the output of the combination circuit 16.

Therefore, according to the output of the combination circuit 16, the MUX 24x selects one of the registers 20x and 22x, the MUX 24y selects one of the registers 20y and 22y, and the average value of the selected X coordinate value is 1 Then, one average value of the Y coordinate values is stored in the output register 26. And this output register 2
6 is supplied to the subsequent stage.

As described above, the six position coordinate data Xa, Ya, Xb, Yb,
When Xc and Yc are input, an average value for the X and Y coordinates is output using two of them (total of four). As a result, it is possible to remove an object having a large moving distance, reduce errors due to averaging, and obtain position detection data from which noise has been removed.

The circuit of the present embodiment is a circuit for realizing such processing by hardware, has a quick operation,
It is possible to reduce the processing load of the subsequent software.

In particular, in the present embodiment, three buffers 0.1.2 are used in the form of a pipeline to receive and process six data. Therefore, an efficient circuit configuration can be achieved by effectively utilizing the storage device, and the circuit scale can be reduced.

FIG. 2 shows another embodiment. The processing after the subtracter 10 and the adder 12 is the same, and therefore, the description is omitted.

In this example, six registers 30-1 to 30-3 are used.
0-6. The digital data output from the A / D converter is stored in the registers 30-1 to 30-30.
-6 are sequentially stored. In the example of FIG.
Xa, Ya, Xb, Yb, Xc, Yc
Is stored.

Then, the registers 30-1, 30-3, 3
0-5 is supplied to the subtracter 10 via the multiplexer 32-1.
Is connected to the adder 12 via the multiplexer 32-3. Similarly, registers 30-2, 30-4, 30
-6 is supplied to the subtractor 10 via the multiplexer 32-2.
It is connected to the adder 12 via the multiplexer 32-4.

The multiplexers 32-1 and 32-
2 sequentially selects data and supplies it to the subtractor 10, or the multiplexers 32-3 and 32-4 sequentially selects data and supplies it to the adder 12. Therefore, difference data and addition data similar to those in the above-described example are obtained in the subtractor 10 and the adder 12.

FIG. 3 shows still another embodiment in which the combination of digital data input to the multiplexers 32-1 to 32-4 in FIG. 2 is changed.

That is, the registers 30-1, 30-2,
30-3 and 30-4 are provided to the subtractor 10 via the multiplexer 32-1 and to the adder 1 via the multiplexer 32-3.
2 are connected. Similarly, registers 30-3 and 30
-4, 30-5, and 30-6 are the multiplexer 32-2.
To the adder 12 via the multiplexer 32-4.

The multiplexers 32-1 and 32-
2 sequentially selects data and supplies it to the subtractor 10, or the multiplexers 32-3 and 32-4 sequentially selects data and supplies it to the adder 12. Therefore, difference data and addition data similar to those in the above-described example are obtained in the subtractor 10 and the adder 12.

As described above, in this example, six registers are prepared for six input digital data. Therefore,
The necessary calculations can be performed by sequentially inputting the six data to the register. Then, the same process is repeated every time six data are input, so that data from which noise has been sequentially removed is supplied to the subsequent stage.

[0039]

As described above, according to the present invention, since a circuit for selecting an added value based on a subtraction result is constituted by hardware, an output from which noise has been removed can be easily obtained. Therefore, efficient processing can be performed by reducing the load on the software in the subsequent stage.

In particular, by connecting the three storage means in a pipeline and shifting the storage contents, it is possible to perform processing on the input six data, and to reduce the circuit scale to achieve effective processing. It can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment.

FIG. 2 is a diagram illustrating a configuration of another embodiment.

FIG. 3 is a diagram showing a configuration of another embodiment.

[Explanation of symbols]

Reference Signs List 10 subtractor, 12 adder, 14 comparator, 16 combination circuit, 181/2 circuit, 20x, 20y, 22
x, 22y registers, 24x, 24y multiplexers, 26 output registers.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Hirozo Yabuta 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Sou Shinohara 2-chome Keihanhondori, Moriguchi-shi, Osaka 5-5 Sanyo Electric Co., Ltd. (72) Inventor Mitsuru Katayanagi 2-5-5 Sanyo Electric Co., Ltd. (72) Inventor Makoto Kanakawa Keihanhondori Moriguchi, Osaka 2-5-5 Sanyo Electric Co., Ltd. F term (reference) 5B068 AA01 BE08 BE12 CC12 DE01 DE02 5B087 AA02 AC02 AC12 AD02 CC26 DJ01

Claims (4)

[Claims] 1. A noise processing circuit for removing noise in digital data of position information detected from a touch panel, comprising: a plurality of storage means for sequentially taking in position information output from the A / D converter; A subtractor for calculating a difference between two pieces of position information taken in the storage means, an adder for calculating an addition value for performing an averaging process of the two pieces of position information taken in the storage means, and a subtractor Selecting means for selecting any of at least two addition values obtained from the adder based on at least two difference values obtained from the above, and a noise processing circuit configured by hardware. 2. The circuit according to claim 1, wherein the position information output from the A / D converter includes an X coordinate value and a Y coordinate value, and these are sequentially output. Have six X coordinate values and three Y coordinate values.
The subtractor calculates two differences from two adjacent X coordinate values, and calculates two differences from two adjacent Y coordinate values. The adder calculates two difference values from two adjacent Y coordinate values. Two addition values are calculated from two X coordinate values, and two addition values are calculated from two adjacent Y coordinate values.
The selection means calculates one addition value for the X coordinate value and one addition value for the Y coordinate value based on two differences for the X coordinate value and the Y coordinate value, respectively. Output noise processing circuit. 3. The circuit according to claim 1, wherein the position information output from the A / D converter includes an X coordinate value and a Y coordinate value, which are sequentially output, and Has either three X-coordinate values and one Y-coordinate value or one X-coordinate value and two Y-coordinate values, and the subtractor stores two X-coordinate values and one in the storage means. The difference between the X coordinate values is calculated at the timing when two Y coordinate values are stored, and the difference between the Y coordinate values is calculated at the timing when two Y coordinate values and one X coordinate value are stored in the storage means. The adder calculates an added value for the X coordinate value at a timing when two X coordinate values and one Y coordinate value are stored in the storage means, and stores the two Y coordinate values and one X coordinate value in the storage means.
At the timing when the coordinate values are stored, an addition value is calculated for the Y coordinate value. The selecting means calculates one addition value for the X coordinate value based on two differences for the X coordinate value and the Y coordinate value, respectively. And a noise processing circuit that outputs one addition value for the Y coordinate value. 4. The circuit according to claim 3, wherein said three storage means are connected in a pipeline manner, and
A noise processing circuit in which one storage means takes in new data and shifts the storage content to the next storage means sequentially.