JPS63211420A - Finger touch type coordinate output device - Google Patents

Abstract

PURPOSE:To exactly detect a coordinate value of a finger touch position on a coordinate input panel, by correcting a temperature drift, based on the potential of the other end of an oscillator, the potential of a common connecting point in one end side in the X axis direction, and the potential of a common connecting point in the other end side in the X axis direction. CONSTITUTION:When the potential of the other end of an oscillator 7 whose one end is grounded, the potential of a common connecting point in one end side in the X axis direction, and the potential of a common connecting point in the other end side in the X axis direction are denoted as E0, Ea and Eb, respectively, a temperature drift is corrected so that the sum of a value which has subtracted the potential Ea from the potential E0, and a value which has subtracted the potential Eb from the potential E0, when a finger touch to a coordinate input panel is not executed. In such a way, a coordinate value of a finger touch position on a touch panel can be detected exactly without being influenced at all by a variation of an environmental temperature.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention provides an input means generally called a finger-touch coordinate input panel, which comprises a resistive layer provided on a substrate and an insulating layer provided on the resistive layer. This invention relates to a finger-touch coordinate output device using a finger-touch coordinate output device.

(Prior art and its problems) Finger-touch coordinate output devices using finger-touch coordinate input panels (hereinafter referred to as touch panels) are described in numerous documents, such as Japanese Patent Laid-Open No. 60-5326. There are many things like that.

In any case, these devices change the touch position to
It is necessary to be able to accurately detect the position on the coordinate axes.
Various efforts have been made to achieve this, but when the environmental temperature fluctuates, the temperature drift causes the finger touch position on the touch panel to be detected as being deviated from the actual coordinate position.

(Purpose of the Invention) This invention was made to solve the above-mentioned conventional problems, and is a method for accurately detecting the coordinate values of a finger touch position on a touch panel without being affected by changes in environmental temperature. The purpose of the present invention is to provide a finger-touch coordinate output device that can perform the following tasks.

(Means for Achieving the Object) The present invention provides a finger-touch coordinate input panel in which a resistive layer is provided on a substrate and an insulating layer is provided on the resistive layer, one end of the resistive layer in the X-axis direction and A plurality of switches are connected at one end to the other end, a plurality of switches are connected at one end to one end of the resistance layer in the Y-axis direction, and a plurality of switches are connected to one end of the resistance layer in the Y-axis direction. The other end of each connected switch and the other end of each switch connected to one end in the Y-axis direction are commonly connected, and one end is connected to the other end of an oscillator whose one end is grounded via a first resistor. The other end of each switch connected to the other end in the Y-axis direction and the other end of each switch connected to the other end in the Y-axis direction are commonly connected and connected to the other end of the oscillator via a second resistor. Potential E at the other end
. A signal for calculating the coordinate value of the finger touch position on the coordinate input panel based on the potential Ea of the common connection point on one end side in the X-axis direction and the potential Ea of the common connection point on the other end side in the X-axis direction. In order to achieve the above object in the finger-touch type coordinate output device including a processing section, the electric potential E is applied when the coordinate input panel is not touched with a finger. to the potential E.

and the potential E. The present invention is characterized in that a correction means is provided for correcting the temperature drift so that the sum of the values obtained by subtracting the potential Eb from the potential Eb becomes zero.

(Function) The touch panel used in the present invention is provided with a preferably transparent resistance layer made of ITO (Indium Tin Oxide) or the like on an electrically insulating substrate made of a preferably transparent material such as a glass base, Further, on the resistance layer, a preferably transparent electrically insulating layer is formed, for example, by a resin coating. Because it is transparent, it can be placed in front of a cathode ray tube, for example, and used as a means of inputting characters, drawings, etc.

Regarding the operation of this finger-touch type coordinate output device, first, a case will be described in which the touch position in the X-axis direction of the touch panel is determined. As shown in FIG. 2, let R be the total resistance value of the resistance layer 1 in the X-axis direction, and let X be the resistance value from the touch position to one end of the resistance layer 1 in the X-axis direction. Therefore, the resistance value from the touch position to the other end of the resistance layer 1 in the X-axis direction is Rx. Further, the resistance value r of the resistors 6 and 8 on each end side of the resistive layer 1 is adjusted so that it becomes r #R.

Now, when you touch the touch panel with your finger, the ground capacity of the human body is 3.
1, two detection circuits are formed, one passing through the resistor 6 at one end of the resistance layer 1 and the other passing through the resistor 8 at the other end, producing a potential EaEa at each common connection point. Therefore, the potential at the other end of the oscillator 7 is set to E. Then, the resistance 111 X from one end of the resistive layer 1 to the touch position is
= [(E □ E b) R+ (E a E
b) ']/[(Eo-Ej)→-(Eo-E
a)]...(1) Since r = R, in the end, the touch position is 1ff
T is TOCK[(E□ Eb)+(Ea Eb)]/[
(Eo-Ea)+(Eo-Ea)]...(2) The a touch position can be determined from the electric potentials EaEaEb at the three points. In addition, K is the above (
2) It is a constant determined by the amplification degree of the arithmetic unit for calculating the equation.

Although the case where the touch position in the X-axis direction of the touch panel is determined has been described above, it goes without saying that the touch position in the Y-axis direction can also be determined in exactly the same manner.

By the way, in an actual device, switches (not shown) are interposed between the resistor 6 and the resistive layer 1 and between the resistor 8 and the resistive layer 1 in FIG. 2, and the resistive layer 1. The on-resistance of the switch and the resistance values of the resistors 6 and 8 change depending on the environmental temperature. Therefore, in the above equation (2), (E.-Ea) and (Eo-Eb
) changes following the temperature, which is a temperature drift and causes the finger touch position on the touch panel to be detected as being shifted from the actual coordinate position. Note that the term (Ea-Eb) in the above equation (2) is
As shown in FIG. 2, since the peripheral circuitry including the touch panel is symmetrical, temperature fluctuations are canceled out and remain constant.

In consideration of such temperature drift, the finger-touch type coordinate output device of the present invention is provided with a temperature drift correction means.In other words, by this correction means, when the touch panel is not touched with a finger, the above-mentioned (( 2) The denominator of equation, that is, [(Eo-E) + (E-Ea
)] is periodically measured and temperature drift is corrected so that this value becomes zero, thereby avoiding deviation in detection of the touch position caused by fluctuations in environmental temperature.

In addition, in this invention, as is clear from the above description, the resistors 6 and 8 are commonly used for determining the touch position in the X-axis direction and the Y-axis direction. In this case, the resistance value r of resistor 6.8
The reason why is adjusted so that r=R instead of r=R is that the length of the resistance layer 1 of a touch panel is generally different in the X-axis direction and the Y-axis direction, and therefore the total resistance value is different in both directions. Therefore, the average of all resistance values in both directions is taken. If the total resistance value of the resistance layer 1 is equal in both directions, it is sufficient to accurately set r=R.

(Example) To explain this invention in more detail based on one example, in FIG. ,
Further, n switches 31 to 3o are connected at one end to the other end. In exactly the same way, at one end of the resistance layer 1 in the Y-axis direction, arbitrary n switches 41 to
4o, and n switches 51 to 5o are respectively connected at one end thereof. Also, X
The other end of the switches 21 to 2o connected to one end in the axial direction,
The other ends of the switches 41 to 4o connected to one end in the Y-axis direction are commonly connected, and through the resistor 6, -.
It is connected to the other end of the oscillator 7 whose end is grounded. Further, the other ends of the switches 31 to 3 connected to the other end in the X-axis direction and the other ends of the switches 51 to 5o connected to the other end in the Y-axis direction are commonly connected and are connected via a resistor 8. and is connected to the other end of the oscillator 7.

A voltage detector 9 for detecting the potential Ea of the common connection point is connected to the common connection point of the switches 21 to 2o and the switches 41 to 4°, and a voltage detector 9 is connected to the common connection point of the switches 21 to 2o and the switches 41 to 4°. A voltage detector 10 is connected to the common connection point of the oscillator 7 to detect the potential Eb of the common connection point, and a voltage detector 11 is connected to the other end of the oscillator 7 to detect the potential Eo of the other end. It is connected.

A subtraction circuit 12.13.14 is connected to the output side of the voltage detectors 9, 10.11. The subtraction circuit 12 is
The subtraction circuit 13 has a function of subtracting the output of the voltage detector 10 from the output of the voltage detector 9, that is, calculating (E - Eb).
The subtraction circuit 14 has a function of subtracting the output of the voltage detector 10 from the output of the voltage detector 11, that is, calculating (Eo - Ea).
It has a function to calculate b).

Subtraction circuits 15 and 16 for temperature drift correction are connected to the output sides of the subtraction circuits 13 and 14, respectively. The subtraction circuit 15 has a function of subtracting a temperature trit correction value α (the details of which will be described later) from the output of the subtraction circuit 13, that is, calculating [(Eo-Ea'')-α1, and the subtraction circuit 16 has the function of Subtract the temperature drift correction value α from the output of the subtraction circuit 14, that is, [(E −Ea) − α]
It has the function of calculating.

An X lees calculation circuit 17 and a Y lees calculation circuit 18 are connected to the output sides of the subtraction circuit 12 and the subtraction circuits 15 and 16. Of these, the X lees calculation circuit 17 includes adjustment circuits 19, 20, and 21 for adjusting the outputs of the subtraction circuits 12, 15, and 16 to zero when no finger is touched, and the output of the adjustment circuit 19 and adjustment. An adder circuit 22 adds the outputs of the circuit 21, that is, obtains [(F8-Eb)+(E□-Eb)], and adds the outputs of the adjustment circuit 20 and the outputs of the adjustment circuit 21, that is, [(Eo- Ea)+(Eo-Ea)
], and a division circuit 24 that divides the output of the adder circuit 22 by the output of the adder circuit 23, that is, divides based on equation (2) above. The Y lees pickling circuit 18 also has the same configuration as the X lees pickling circuit 17.

On the output side of the X-lees pickling circuit 17, the adding circuit 23 is connected.
The output of [(E.-Ea) + (Eo-Eb)]
A detection circuit 25 detects temperature drift based on the output of
Similarly, a detection circuit 26 is connected to detect a finger touch on the touch panel based on the output of the addition circuit 23. The detection circuit 26 is a so-called comparison circuit, and the output of the addition circuit 23 [(Eo-Ea)
)] changes from zero voltage to a certain level of positive voltage due to a finger touch, and compares the output of the adder circuit 23 with the threshold voltage.
The circuit 29 is configured so that the signal rOJ is outputted to the input circuit 29.

An analog switch circuit 2 is provided on the output side of the detection circuit 25.
7 is connected, and the input side of this analog switch circuit 27 is also connected to the output side of the division circuit 24 of the XlN1 arithmetic circuit 17 and the output side of the division circuit (not shown) of the Y lees pickling circuit 18. has been done. Analog switch circuit 27
The switching operation is controlled based on a signal from the microcomputer circuit 29, that is, when there is no finger touch, the output of the detection circuit 25 is controlled to be output to the A/D conversion circuit 28 at the next stage. When a finger touch is made, the output of the XOb calculation circuit 17 and the output of the Y lees calculation circuit 18 are alternately switched to the A/D conversion circuit 2.
It is controlled to output to the 8 side.

The microcomputer circuit 29 is connected to the output side of the A/D conversion circuit 28 and to the input side of the D/A conversion circuit 30. The output side of the D/A conversion circuit 30 is connected to the input sides of the subtraction circuits 15 and 16 via one switching contact S and the common contact C of the selection switch 32, respectively, and The switching contact G is grounded. In addition, the above-mentioned "in" circuit 2
A signal from 9 is transmitted to the switches 2 to 2.31n to 3.41 to 4. 5. ~5o given to the side, n
n It is configured such that on-on control of these is performed. Note that the resistance value r of the resistor 6.8 is adjusted so that r=R as described above.

Next, the operation of the finger touch type coordinate output device will be explained. First, initial setting work regarding the X-axis direction of the touch panel is performed. That is, the selection switch 32 is connected to the switching contact G side without touching the touch panel, and the ground potential is reduced via the selection switch 32 in the circuit 15.1.
Connected to one input terminal of 6. As a result, subtraction circuit 1
2, 13.14 each output A1.8'1. C1 will be applied as is to the adjustment circuit 19, 20, 21 without changing the output value. In this state, microcomputer circuit 2
By the signal from 9, X@force direction switch 2~2 and 3
1 to 3o are turned on, and the switches 41 to 4o and 51 to 5o in the Y-axis direction are turned off to adjust the outputs A3.
B3. Adjustment circuit 19.20.21 so that C3 becomes zero
Adjust. At this time, the output of the subtraction circuit 12.13°14, that is, (Ea-E
b), (EQ - Ea), and (Eo - Eb) are respectively input, so if the above adjustment is performed by the adjustment circuit 19, 20, and 21, the above equation (2) regarding the X-axis direction will be (
Each of the terms E-Eb), (Eo-Ea), and (Eo-Eb') is adjusted to zero voltage without touching the touch panel with a finger. Therefore, the adjustment circuit 20.2
After the outputs of 1 are added by the adder circuit 23, the output of the adjusting circuit 25 that precedes it also becomes zero voltage.

The initial setting work for the Y-axis direction of the touch panel is also performed in substantially the same way as the initial setting work for the X-axis direction. That is, in this case, X@force direction switches 2 to 2 and 31
-3o is turned off, and switches 4-4 and 51-5o in the Y-axis direction are turned on, and the adjustment circuit incorporated in the Y-lees pickling circuit 18, specifically the subtraction circuit 12, 15, 16, is turned on. Output A1.
B2. By the adjustment circuit (not shown) to which C2 is input,
Adjust so that the output of each adjustment circuit becomes zero.

As a result, (E
-Ea), (E.

-Ea') and (Eo-Eb) are adjusted to zero potential without touching the touch panel with a finger.

Next, the analog switch circuit 27 is switched and connected to the detection circuit 25 side by a signal from the microcomputer circuit 29, and the output (zero voltage here) of the detection circuit 25 is connected to the analog switch circuit 27. A/D transformation circuit 28 and microcomputer circuit 2
9, and based on this input data, the microcomputer circuit 29 outputs to the D/A converter circuit 30 a digital signal that makes the output value of the D/A converter circuit 30 zero. Then, the selection switch 32 is switched to the switching contact S side. As a result, zero is set as the temperature drift correction value α.

When the environmental temperature changes in this state, the output of the detection circuit 25, that is, the value of [(E□Ea) + (Eo-Eb)] changes to follow the change. Therefore, this variation E
The value is transferred to the analog switch circuit 27゜A/D conversion circuit 28
This input data (
E value), the microcomputer circuit 29 converts the D/A conversion circuit 3
A digital signal is provided to the D/A conversion circuit 30 such that the temperature drift correction value α output from 0 is added and corrected by half the value of the variation E value, that is, the E/2 value. Thus E
The temperature drift correction value α which has been added and corrected by /2 value is given to each subtraction circuit 15.16 via the selection switch 32, and in each subtraction circuit 15.16, [(E −
E i-α] and [(Eo-a Ea)-α] are calculated, and the output fluctuation E value of the detection circuit 25 is corrected to zero.

Such a correction is periodically and repeatedly executed by the main circuit 29 during the period when no finger is touched, and in other words, a new E value (E value is correct or a negative value) appears,
The microcomputer circuit 2 is configured so that the value of the temperature drift correction value α output from the D/A conversion circuit 30 is added by E/2 value.
9, and the temperature drift correction value α corresponding to the environmental temperature is obtained from time to time. Note that the measurement of the variation E value is performed only during a period when no finger touch is detected by the detection circuit 26.

Here, when a finger touches the touch panel, the output of the adding circuit 23, that is, [(E□ Ea) + (Eo-Eb
)] rises from zero voltage to a certain level of positive voltage,
The finger touch detection signal from the detection circuit 26 is sent to the microcomputer circuit 29.
The microcomputer circuit 29 receives this detection signal and starts calculating the X and Y coordinate values of the finger touch position on the touch panel. In this case, the coordinate values are calculated alternately for the X-axis and the Y-axis, and specifically, based on the signal output from the microcomputer circuit 29, the coordinate values are calculated for the switches 2 to 2 in the X-axis direction.
31 to 3o and switches in the Y-axis direction 4 to 4.51 to 5o are alternately driven on and off, and the analog switch circuit 27
In synchronization with the on/off operation of each switch in the axial direction and the Y-axis direction, it is alternately connected to the division circuit 24 of the X-lees pickling circuit 17 and the division circuit (not shown) of the Yfi calculation circuit 18. At this time, the temperature drift correction value α immediately before the finger touch is input to the subtraction circuits 15 and 16. now,
Considering the case where the coordinate value in the X-axis direction is calculated, in this case, the switches 21 to 2o and 31 to 3 in the X-axis direction
o is turned on, and switches 41 to 4 in the Y-axis direction are turned on.
and 51 to 5o are off, and each subtraction circuit 12.13.
14, (Ea-Eb), (E
o-Ea) and (Eo-Ea) are calculated, respectively. Among these, the output (Ea-Eb) of the subtraction circuit 12 is
As described above, since the circuits surrounding the touch panel are symmetrical, the temperature fluctuations are canceled out and the temperature is directly applied to the X-lees calculation circuit 19. On the other hand, the output of the subtraction circuit 13 (Eo-Ea) and the output of the subtraction circuit 14 (Eo
-Eb) includes variations due to temperature drift, as described above, and these outputs are subtracted by the temperature drift correction value α from each output value by the subtraction circuits 15 and 16 in the next stage, respectively. That is, it is input to the X lees soaking calculation circuit 17 after the fluctuation due to temperature trit is corrected. In this way, the X-lees pickling circuit 17 uses the output signal that does not include the variation due to temperature drift or has the variation corrected, and uses the addition circuits 22, 23 and the division circuit 24 to calculate the equation (2) above. calculation is performed,
The processed signal is given to a microcomputer circuit 29 via an analog switch circuit 27 and an A/D conversion circuit 28, and an accurate X coordinate value is calculated. The case where the coordinate values in the Y-axis direction are extracted is also carried out in the same manner as described above. In this way, the coordinate values of the finger touch position on the touch panel can be accurately detected without being affected by changes in environmental temperature.

Note that when you release your finger from the touch panel, the detection circuit 26 detects this, and the fine circuit 29 restarts the measurement of the output fluctuation E value of the detection circuit 25, and the temperature drift correction value α is determined according to the environmental temperature. is required from time to time.

(Effects of the Invention) As described above, according to the finger touch coordinate output device of the present invention, when the coordinate input panel is not touched with a finger, the value obtained by subtracting the potential Ea from the potential Eo and the potential Eo
Since a correction means is provided to correct temperature drift so that the sum of the value obtained by subtracting the potential Eb from This has the effect of being able to accurately detect.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the apparatus of the present invention, and FIG. 2 is a schematic block diagram showing the principle of the apparatus shown in FIG. 1. 1...Resistance layer 21-2.31-3n. 4-4.51-5. ... Switch n 6.8 ... Resistor 7 ... High frequency oscillator 13.14, 15.16 ... Subtraction circuit 23 ... Addition circuit 29 ... Microcomputer circuit α ... Temperature drift correction field

Claims (2)

[Claims] (1) A finger-touch coordinate input panel has a resistive layer on a substrate and an insulating layer on the resistive layer, and a plurality of switches are installed at one end and the other end of the resistive layer in the X-axis direction. A plurality of switches are connected at one end, and a plurality of switches are connected at one end to one end and the other end of the resistance layer in the Y-axis direction, and the other end of each switch connected to the one end in the X-axis direction and the
The other end of each switch connected to one end in the axial direction is connected in common, and one end is connected to the other end of the oscillator which is grounded via a first resistor, and each switch connected to the other end in the X-axis direction is connected in common. The other end and the other end of each switch connected to the other end in the Y-axis direction are commonly connected and connected to the other end of the oscillator via a second resistor, and the potential E_0 at the other end of the oscillator and the other end of the switch connected to the other end in the Y-axis direction are connected in common. Potential E_ of the common connection point on one end side in the direction
a and a potential E_b of the common connection point on the other end side in the X-axis direction, the finger touch coordinate output device includes a signal processing unit that calculates coordinate values of a finger touch position on the coordinate input panel. Temperature drift is corrected so that the sum of the value obtained by subtracting the potential E_a from the potential E_0 and the value obtained by subtracting the potential E_b from the potential E_0 becomes zero when no finger is touched on the coordinate input panel. A finger touch type coordinate output device characterized by being provided with a correction means. (2) The signal processing unit is configured to control the potential E_0 and the potential E
a first subtraction circuit that calculates the difference between the electric potentials E_0 and E_b; The correction means includes a third subtraction circuit interposed between the first subtraction circuit and the addition circuit to obtain a difference between the output obtained by the first subtraction circuit and a temperature drift correction value. a fourth subtraction circuit interposed between the second subtraction circuit and the addition circuit to calculate the difference between the output obtained by the second subtraction circuit and the temperature drift correction value, and the addition circuit a detection circuit that detects a finger touch on the coordinate input panel based on the output of the circuit; and a detection circuit that detects a finger touch on the coordinate input panel based on the output of the addition circuit, and a detection circuit that detects a finger touch on the coordinate input panel based on the output of the addition circuit. 2. The finger-touch coordinate output device according to claim 1, further comprising: a subtraction circuit of No. 3 and a control section that provides a temperature drift correction value to the fourth subtraction circuit.