JPH0350286B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] In a coordinate input device that inputs coordinate values of a position touched by an input pen on a resistive film into a computer, a noise signal is superimposed on the detected coordinate signal to indicate a different position. It may be changed to the signal. Therefore, abnormal values are removed from a plurality of coordinate values obtained from one coordinate, and the remaining coordinate values are averaged to eliminate the influence of noise signals.

[Industrial application field]

The present invention relates to a coordinate input device for manually inputting coordinate values into a computer, and more particularly to a coordinate input device equipped with a circuit for eliminating the influence of noise signals.

FIG. 3 is a principle diagram showing the handwriting input board.

In the figure, the handwriting input board is resistor film 1.
and an input pen 2, and the resistive film 1 is composed of, for example, ITO (In ₂ O ₃ .
Resistive film 12 consisting of SnO ₂ ) etc., and Resistive film 1
Drive electrodes 13a, 13b arranged on the four sides of 2.
13c and 13d. The input pen 2 also has a contact 21 at its tip, and the contact 21 is connected to the coordinate signal conversion circuit 3 via a capacitor 22. The coordinate signal conversion circuit 3 is an amplifier circuit 3
1, a filter 32, a phase difference detection circuit 33, etc., and converts the coordinate signal input from the input pen 2 into coordinate values and outputs the coordinate values.

In such a handwriting input board, the drive electrode 13
AC voltage signal with Esinωt at a (hereinafter referred to as signal)
and Esin to the drive electrode 13c facing it.
(ωt+90°) AC voltage signal (hereinafter referred to as signal)
When applying , the phase of the signal at the position closest to the drive electrode 13a of the resistive coating 12 is 0 degree, and the phase difference of the signal increases as the distance from the drive electrode 13a parallel to the X axis increases. The phase of the signal at the position closest to 13c is
It becomes 90 degrees. Therefore, the contact 21 of the input pen 2
When the X coordinate value is brought into contact with the resistive film 12, the coordinate signal conversion circuit 3 outputs an X coordinate value.

Similarly, a signal Esinωt is applied to the drive electrode 13b,
In addition, Esin(ωt+
90°), the phase of the signal at the position closest to the drive electrode 13b of the resistive film 12 is 0 degrees, and the drive electrode 13b is applied parallel to the Y axis.
The phase difference of the signal increases as the distance from the drive electrode 13d increases, and the phase of the signal at the position closest to the drive electrode 13d becomes 90 degrees. Therefore, contact 2
1 in contact with the resistive coating 12.
3a to the drive electrode 13d, and the drive electrode 13c.
By switching the application of a signal from the Y coordinate signal conversion circuit 3 to the drive electrode 13d, the Y coordinate value is output from the coordinate signal conversion circuit 3.

However, the above-mentioned handwriting input board is of a capacitive coupling type in which the input pen 2 itself has a stray capacitance, and therefore easily picks up noise signals from the outside. Therefore, a coordinate input device using such a handwriting input board is required to include a circuit that can eliminate external noise signals.

[Conventional technology]

FIG. 4 is a block diagram showing an arithmetic circuit in a conventional coordinate input device.

In order to eliminate external noise signals, a coordinate input device using a handwriting input board detects a plurality of coordinate signals for one coordinate and uses the average value as a value indicating the coordinates at that point.

That is, in the figure, the output of the coordinate signal conversion circuit 3 is an analog signal, and the conventional arithmetic circuit 4 includes an A/D conversion circuit 41 that converts the coordinate values output from the coordinate signal conversion circuit 3 into digital signals, and an A/D conversion circuit 41 that converts the coordinate values output from the coordinate signal conversion circuit 3 into digital signals. It consists of an average value calculation circuit 42 that calculates an average value, and a coordinate signal conversion circuit 3 to an A/D conversion circuit 4.
The coordinate values inputted to the average value calculation circuit 42 via 1 are sequentially integrated and divided by the number of inputted coordinate values to calculate the average value of the X coordinate and the Y coordinate, respectively.

The average value of the X coordinate and Y
The average value of the coordinates is input into the computer as a value indicating the coordinates at that point.

[Problem that the invention seeks to solve]

The conventional coordinate input device equipped with the above calculation circuit is
Since abnormal values due to external noise signals are averaged without excluding them, the influence of abnormal values will be dispersed and included in other coordinate values, and the average value will deviate from the value indicating the original coordinates. There was a problem.

[Means for solving problems]

FIG. 1 is a float chart showing the operation of the arithmetic circuit in the coordinate input device of the present invention.

The above problem is that in the coordinate input device equipped with a resistive film and an input pen as shown in Fig. 1, when the input pen is brought into contact with the resistive film of the handwriting input board, multiple points are repeatedly detected at the contact point. The arithmetic circuit that receives the X-coordinate signal and Y-coordinate signal, calculates and outputs the average X-coordinate value and average Y-coordinate value from them, digitizes the X-coordinate signal and Y-coordinate signal and converts them into X-coordinate values and Y-coordinate values. An A/D conversion circuit for conversion, a plurality of registers that individually and temporarily store a plurality of X-coordinate values and Y-coordinate values, and a temporary The average X coordinate value of
a first average value calculation circuit that calculates a provisional average Y-coordinate value; a deviation value between the provisional average X-coordinate value and a plurality of X-coordinate values stored in the register; a provisional average Y-coordinate value and the register; A deviation value detection circuit detects a deviation value from a plurality of Y coordinate values stored in , and if the deviation value detected by the deviation value detection circuit exceeds a preset tolerance range, a provisional average X coordinate value, Temporary average Y
An abnormal value elimination circuit that eliminates X and Y coordinate values that deviate from the coordinate values, and an abnormal value elimination circuit that eliminates X and Y coordinate values that are not excluded.
This problem can be solved by including a second average value calculation circuit that calculates the average value of the coordinate values and outputs the average X coordinate value and Y coordinate value.

[Effect]

From a plurality of X coordinate values or Y coordinate values indicating the same point in Figure 1, remove abnormal values and calculate the average value of the remaining signals, and calculate the average value and calculate the X coordinate value or Y coordinate value at that point. By setting it as a value, it is possible to eliminate the influence of a noise signal superimposed on the coordinate signal from the outside.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a block diagram showing one embodiment of the arithmetic circuit in the coordinate input device of the present invention, and the same objects are represented by the same symbols throughout the figures.

In FIG. 2, the arithmetic circuit 5 used in the coordinate input device of the present invention includes an A/D conversion circuit 41 that converts coordinate values into digital signals, and a plurality of registers 51 that store X coordinate values or Y coordinate values. a first average value calculation circuit 42 that calculates the average value of the coordinate values stored in the register 51; and a deviation value that detects the deviation value between the average value and the coordinate values stored in the register 51. a detection circuit 53; an abnormal value elimination circuit 54 that compares the deviation value with a preset allowable range of deviation values and eliminates abnormal values; and an abnormal value elimination circuit 54 that calculates the average value of the coordinate values after eliminating the abnormal values. 2 average value calculation circuits 55.

In FIGS. 1 and 2, a plurality of X-coordinate signals or Y-coordinate signals repeatedly detected at the contact point when an input pen is brought into contact with the handwriting input board are as follows:
The coordinate signal conversion circuit 3 converts the signal into an X coordinate value or a Y coordinate value and inputs it to the arithmetic circuit 5, where the A/D
It is converted into a digital signal by the conversion circuit 41 and temporarily stored in the register 51. This coordinate input device is designed to eliminate external noise signals.
It is configured to detect a plurality of coordinate signals for one coordinate, and the obtained plurality of coordinate values are stored in separate registers 51, respectively.

As a means for eliminating abnormal values from the coordinate values stored in the register 51, a plurality of registers 51, namely
The coordinate values stored in (1) to (n) are sequentially input to the average value calculation circuit 42, the average value α of the coordinate values is calculated, and this is input to the deviation value detection circuit 53. Next, each coordinate value stored in the register 51 is sequentially input to a deviation value detection circuit 53 and an abnormal value elimination circuit 54, and the deviation value detection circuit 53 calculates the deviation between the average value α and the input coordinate value. The value β is detected and inputted to the abnormal value elimination circuit 54. An allowable range of deviation values is preset in the abnormal value elimination circuit 54, and if the deviation value β is within the allowable range of deviation values, the gate is opened and the input coordinate value is passed through, and the deviation value β is set as the deviation value. If it is outside the allowable range, the input coordinate value is blocked from passing.

Therefore, the coordinate values that pass through the abnormal value elimination circuit 54 and are input to the average value calculation circuit 55 are coordinate values after eliminating abnormal values, and by calculating the average value from these coordinate values, the external Therefore, it is possible to eliminate the influence of noise signals superimposed on the coordinate signals.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a coordinate input device equipped with a circuit that can eliminate external noise signals.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the operation of the arithmetic circuit in the coordinate input device of the present invention, FIG. 2 is a block diagram showing an embodiment of the arithmetic circuit in the coordinate input device of the present invention, and FIG. 3 is a handwriting input board. FIG. 4 is a block diagram showing an arithmetic circuit in a conventional coordinate input device. In the figure,
3 is a coordinate signal conversion circuit, 5 is an arithmetic circuit, 41 is an A/D conversion circuit, 42 is a first average value calculation circuit,
51 is a register, 52 is a storage circuit, 53 is a deviation value detection circuit, 54 is an abnormal value elimination circuit, and 55 is a second average value calculation circuit.

Claims (1)

[Claims] 1. When an input pen is brought into contact with the resistance film of a handwriting input board, a plurality of X-coordinate signals and Y-coordinate signals repeatedly detected at the contact point are input, and the average X-coordinate is determined from these signals. The calculation circuit that calculates and outputs the average Y-coordinate value includes an A/D conversion circuit that digitizes the X-coordinate signal and Y-coordinate signal and converts them into X-coordinate values and Y-coordinate values; A plurality of registers that individually and temporarily store Y coordinate values, and a register that calculates a temporary average X coordinate value and a temporary average Y coordinate value from the multiple temporarily stored X coordinate values and Y coordinate values. 1, a deviation value between a provisional average X coordinate value and a plurality of X coordinate values stored in the register, a provisional average Y coordinate value and a plurality of Y coordinate values stored in the register; a deviation value detection circuit that detects the deviation value of
An abnormal value elimination circuit that eliminates X-coordinate values and Y-coordinate values that deviate from the temporary average Y-coordinate value, and calculates the average value of the excluded X-coordinate values or Y-coordinate values and calculates the average X-coordinate value and Y-coordinate value. A coordinate input device comprising: a second average value calculation circuit that outputs;