JP2689900B2 - Resistive film touch panel controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for detecting and controlling the pressing position of a resistive film contact type touch panel, and particularly to accurately specify the pressing position without being affected by the secular change or temperature change of the resistive film. The present invention relates to a resistive film contact type touch panel control device that can be used.

[0002]

2. Description of the Related Art A resistance film contact type touch panel can be used as an input means for various devices such as a computer and a handy terminal for the purpose of improving man-machine interface because input is possible by simply pressing it with a finger or a pen tip. Widely used. In this resistance film contact type touch panel, two resistance films having linear resistance values are made to face each other through a micro spacer such as an insulating resin. In a normal state, these two resistance films do not contact each other, and Alternatively, when the pen tip or the like presses the two resistive films, the resistive films contact each other at the pressing position. Then, in principle, the two-dimensional coordinate position of the pressed position of the resistive film is specified by calculating from the linearity of the characteristics based on the resistance value in the unpressed state and the resistance value that changes due to contact. is there. Therefore, in detecting the pressed position of this type of touch panel, the detection of the resistance value and the calculation process based on the detected resistance value are important elements for specifying the pressed position.

As a conventional technique for detecting the pressed position in this type of resistive film contact type touch panel, Japanese Patent Laid-Open No. 04-379 has been proposed.
There is a technique disclosed in Japanese Patent No. 21. The technique disclosed in Japanese Patent Application Laid-Open No. 04-37921 is to detect the detection data from the touch panel by analog / digital conversion and calculate the data by the CPU to specify the pressing position. By selecting the basic parameters of calculation used for detection from some parameters preset in the application program to detect the pressed position, it is affected by changes in the resistance value of the touch panel over time and changes due to environmental changes. This is a technology for accurately detecting the pressed position without using.

[0004]

As described above, in detecting the pressed position of this type of touch panel, the detection of the resistance value and the calculation process based on the detected resistance value are important factors for specifying the pressed position. There is. However, the resistance film used in the touch panel has many physical elements that are affected by changes in the external environment such as temperature changes and operating conditions, as well as changes over time. Further, in addition to the resistance film, the power source to be applied to measure the resistance value has internal impedance.
Therefore, due to these various factors, even if the position is calculated by calculating based on the detected value, the basic parameter itself has changed, and the detected position is actually pressed. There is a problem that the correct position cannot be input using the touch panel as a result.

Japanese Laid-Open Patent Publication No. 04-37921, which has been mentioned above as a conventional technique, is one technique for solving such a problem. However, basic parameters for calculation used for detecting a pressed position are previously stored in an application program. Since some parameters are set, it is not always guaranteed that the parameters that match the changed conditions are set. Therefore, it is not possible to specify the exact pressing position depending on the changing conditions,
In addition, in order to make the detection more accurate, it is necessary to set a large number of parameters, and as a result, there is a problem in that selection and calculation means for those parameters are complicated.

[0006]

The resistance film contact type touch panel control device according to the present invention solves the above-mentioned problems inherent in the prior art, and even if the resistance value of the resistance film changes due to the external environment. The present invention provides a control device that can always calculate an accurate pressed position without performing an operation such as adjustment.

In the resistive film contact type touch panel control device according to the present invention, two resistive films having a linear resistance value are superposed via a spacer, and one resistive film is provided at both ends in the X-coordinate axis direction. Electrodes are provided on both ends of the resistance film in the Y-coordinate axis direction. The two resistance films do not come into contact with each other when the resistance film surfaces are not pressed, and when the resistance films are pressed, the two resistance films are pressed at the pressing points. In the resistive film contact type touch panel control device that specifies the coordinate position of the touching point of the resistive film contact type touch panel, the voltage applied between each electrode and the electrode potential detection means connected to each electrode to detect the potential of the electrode. A voltage application power supply for supplying the voltage, switching means for selectively switching the voltage application between the electrodes for each coordinate axis, and an analog for converting the analog potential detected by the electrode potential detecting means into a digital value. It has a digital conversion means and a storage calculation means for performing a calculation based on the digitally converted potential information of each electrode input from the analog / digital conversion means and specifying the coordinate position of the pressing point of the resistive film contact type touch panel. ing.

Then, the memory operation means applies a voltage-applied power source to each coordinate axis when the resistive film surface is not pressed.
When a voltage is supplied and a current flows through the resistance film,
The maximum voltage and the minimum voltage are periodically measured at the electrodes provided at both ends of the membrane, and the values are updated and stored. Further, when the resistive film surface is pressed, the potential gradient is obtained from the difference between the stored maximum voltage and minimum voltage in the coordinate axis direction to which the voltage is applied, and the potential gradient is calculated by the analog / digital conversion means. Equally divided by the number of quantization steps that have, by sequentially comparing the potential information based on the equally divided potential and the detected potential value in the coordinate axis direction corresponding to the pressing point, the coordinate position in the coordinate axis direction is specified, Then, the voltage application coordinate axis is changed by the switching means, and the coordinate position in the other coordinate axis direction is specified by the same means.

Further, in the resistance film contact type touch panel control device according to the present invention, the potential in the coordinate axis direction corresponding to the pressing point in the coordinate axis direction to which the voltage is applied is detected in the electrode potential of the coordinate axis orthogonal to the coordinate axis. It is characterized in that the means detects.

Further, the storage / calculation means has the number of quantization steps of 2 which the analog / digital conversion means has.
Expressed as a decimal number, the potentials corresponding to the bits from the leftmost end to the rightmost end of the binary number are sequentially added, and the magnitude of the detected potential at the pressing point is compared. If the potential is smaller than the detected potential at the pressing point, the bit is compared. The feature is that the coordinate position is specified by setting to 1 and 0 in the case of a large value.

[0011]

[Operation] The effective area on the touch panel is finely divided at equal intervals in each coordinate axis direction, the effective area is measured every time the coordinate position is specified, and the measured electric potential is used as a reference for comparison with the detected electric potential at the pressing point. Since it is performed, even if the resistance value of the resistance film changes, the position on the touch panel can be specified relatively without change.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resistance film contact type touch panel control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a resistive film contact type touch panel control device according to the present invention, FIG.
3 is a flow chart for explaining an operation of identifying the pressed position of the touch panel control device.

In FIG. 1, the resistive film contact type touch panel 1 includes a transparent resistive film A10, which is two resistive films having a linear (linear) resistance value characteristic, through a transparent insulating micro spacer (not shown). The transparent resistance film B11 and the transparent resistance film B11 are overlapped with each other, and the two resistance films do not come into contact with each other when not pressed with a finger or a pen tip. Is configured.

The transparent resistive film A10 has electrodes XR 100 and electrodes XL 101 as electrodes in the X-coordinate axis direction on the left and right ends.
The transparent resistance film B11 has an electrode YU 110 and an electrode YD 111 as electrodes in the Y coordinate axis direction at both upper and lower ends. These electrodes are the voltage application power supply 28 of the touch panel control device 2 and its internal resistances R1 and R1.
227 and a switching contact xy26 are connected, and a voltage is applied to the transparent resistance film A10 in the X coordinate axis direction, and a voltage is applied to the transparent resistance film B11 in the Y coordinate axis direction.
The voltage application in each direction is selectively switched appropriately by the switching contact xy26.

The touch panel control device 2 further includes voltage follower circuits 22, 23, 24, 25, which are means for detecting the potential of each electrode of the touch panel, a potential detecting section 20, and a storage calculating section 21. .

In this voltage follower circuit, the input impedance is a high impedance close to infinity, and the circuit corresponding to each electrode of the potential detected by the input is applied to the potential detecting section 20 as the detection output DET0, DET1, DET2, DET3 of the electrode. Send out.

The potential detecting section 20 is an analog / digital converting means for digitally converting the potential information of the analog signal input from each voltage follower circuit and sending it to the storage / calculation section 21.

The storage / calculation unit 21 mainly includes the CPU 210 and R
It is composed of AM 211 and ROM 212, and digitized potential information written in RAM 211 is stored in ROM 21.
2 based on the program stored in the CPU 21
0 performs the processing described later to specify and output each coordinate position of the X coordinate axis / Y coordinate axis.

The coordinate position detecting operation of the resistive film contact type touch panel control device thus constructed will be described below.

First, in the state where the touch panel is not pressed, this control device periodically switches the switching contact xy26 to periodically detect the initial voltage in the X coordinate axis direction and the Y coordinate axis direction.

That is, when the switching contact xy26 is in the inoperative state, the voltage from the voltage applying power source 28 is applied in the Y coordinate axis direction, and the potential of the electrode Yu 110 is applied to the voltage follower circuit 2.
2 and outputs as DET0, and the potential of the electrode YD 111 is detected by the voltage follower circuit 25 and DET3.
Output as Further, when the switching contact xy26 is in operation, the voltage from the voltage applying power supply 28 is applied in the X coordinate axis direction, and the potential of the electrode XR 100 is applied to the voltage follower circuit 2.
It is detected by 3 and output as DET1, and the potential of the electrode XL is detected by the voltage follower circuit 24 and output as DET2.

These detected potentials are detected by the potential detection unit 2
0 is analog / digital converted and stored in the RAM 211 of the storage / calculation unit 21. DET0 is the maximum voltage value in the Y coordinate axis direction, DET1 is the maximum voltage value in the X coordinate axis direction, and DET1 is the maximum voltage value in the X coordinate axis direction.
ET2 is stored as the minimum voltage value in the X coordinate axis direction, and DET3 is stored as the minimum voltage value in the Y coordinate axis direction.

Since this potential detection is periodically performed and the contents of the RAM 211 of the storage operation unit 21 are rewritten each time, even if the internal resistances R1 and R2 of the voltage application power supply 28 are changed.
Even if 27 is changed, the data as the initial value of the calculation to be described later always has the latest contents according to the state at that time.

Next, the operation when the touch panel is pressed with a finger or a pen tip will be described.

When the touch panel is pressed with a finger or a pen tip, the transparent resistance film A10 and the transparent resistance film B11 which are superposed are brought into contact with each other at the pressed position, and are orthogonal to the coordinate axis to which the voltage is applied at that time. The potential due to the leakage current is detected at the electrode on the coordinate axis.

For example, when the touch panel is pressed while voltage is applied to the transparent resistance film B11 (Y coordinate axis direction), the electrode X of the transparent resistance film A10 (X coordinate axis direction) is pressed.
On the R 100 or the electrode XL 101, the potential at the pressed point corresponding to the value of the resistance value of the transparent resistance film B11 equally divided between the electrodes in the Y coordinate axis direction is detected. At this time, the electrodes (XR 100 or XL 10) in the transparent resistance film A10 are
The resistance value from 1) to the pressing point can be neglected because the input impedance of the voltage follower circuits 23 and 24 is very high.

In this way, the potential corresponding to the pressing point in the coordinate axis direction to which the voltage is applied at that time is detected at the electrodes of the orthogonal coordinate axes.

As a result, since the alternative detection logic which is the initial value voltage detection logic is broken, it can be detected that the touch panel is pressed. Then, the coordinate position on the X coordinate axis and the coordinate position on the Y coordinate axis of the pressed portion are detected by the processing operation shown in the flowchart of FIG.

The detection processing operation will be described below with reference to FIG.

Step 1 (S1), Step 2 (S2)
The process (1) is an initial value setting or its confirmation operation which is a prerequisite for the detection processing operation.

The maximum resolution bit value of the stored value set in the parameter m in step 1 (S1) determines the accuracy of the position determination on the touch panel, and the potential detection corresponding to the resistance value of the distance from the electrode. Is a binary number indicating how the distance between the electrodes in each coordinate axis direction is divided. This is determined by the value of the number of quantization steps in the analog / digital conversion performed by the potential detecting section 20, and the analog value of the detected potential is converted into a 10-bit digital value and sent to the storage calculating section 21. If it is a device, the effective area on the touch panel is 1
It is divided into 024 equal parts, and this parameter m becomes m = 10.

In step 2 (S2), the maximum voltage and the minimum voltage in each coordinate axis direction are confirmed. That is, the maximum voltage and the minimum voltage in the X coordinate axis direction are obtained by DET1 and DET2, and Y is obtained by DET0 and DET3.
Check the maximum voltage and the minimum voltage in the coordinate axis direction.
If there is data for which no data has been set (No in the determination), data that has not been set is detected before proceeding to the following steps. The confirmation of the maximum voltage and the minimum voltage in each coordinate axis direction is to store the effective area on the touch panel in the pressing position detection process to be performed.

At step 3 (S3), the switching contact xy26 is operated to apply a voltage in the X coordinate axis direction, and then step 4
In (S4), the electrode YU 110 in the Y coordinate axis direction and the X of the pressing point detected by the corresponding voltage follower circuit 22
A process of extracting a potential corresponding to the coordinate position in the coordinate axis direction is performed.

In step 5 (S5), the potential of DET0 of the voltage follower circuit 22, which is the detection output corresponding to the coordinate position in the X coordinate axis direction, is the stored maximum voltage (DET1) and minimum voltage in the X coordinate axis direction. It is confirmed that it is within the range of (DET2), and the stored DET
Confirm the normality of 1 and DET2. If the determination in this step is No, it means that the stored DET1 and / or DET2 is not normal, so DET
Start again from the operation of extracting the value of 1 and / or DET2.

When all the operations up to step 5 proceed normally, next, the preparation for starting the calculation process of the coordinate position of the X coordinate axis is performed in step 6 (S6), and the variable n in the series calculation performed in the subsequent steps is performed. N is the initial value of each
= 1 and i = 1. Further, the function of i in the calculation in the X coordinate axis direction is defined as αX (i), and it is set to αX (i) = 1. The function αX (i) can take only 1 or 0. This αX (i) is a function corresponding to a bit position that represents a potential for comparison determination described later.

Then, the process from step 7 (S7) to step 9 (S9) until the determination is Yes is X.
This is a calculation process for specifying the coordinate position in the coordinate axis direction.

Here, the principle of the calculation process for specifying the pressed point on the touch panel in the present invention will be described. First, as described above, the electric potential on the X coordinate axis is detected by the detecting means on the Y coordinate axis orthogonal to the electric potential (corresponding to DET0 in the above description). Then, the potential and the effective area on the touch panel are compared with the potential at the position that is sequentially added by "1 of the power of 2", and the distance from the pressing point is defined by the maximum and the maximum. The determination is made within the range of resolution.

That is, the position of the electrode XR 100 having the maximum voltage and the electrode XL 10 having the minimum voltage on the X coordinate axis are set.
The position of an arbitrary point on the X coordinate axis between the position 1 and the position of 1 can be represented by a potential value obtained by dividing the potential slope of the difference between the maximum voltage and the minimum voltage with the above-mentioned maximum resolution. Then, as described above, in the case of a device that converts the analog value of the detected potential into a 10-bit digital value and sends it to the storage operation unit 21, this maximum resolution is 1024 (the maximum resolution bit value is 10 ), The potential gradient between the electrodes is 1024
The detected potentials are compared with the equally divided potentials. As a comparison method, the potentials at the positions that are sequentially added by "1 of the power of 2" are compared. In other words, the potential represented by 10 bits is sequentially compared for each bit from the leftmost MSB to the rightmost LSB.

For example, first, "1 of 2" corresponding to MSB
It is compared with the electric potential at the position of "multiplier 1". If the detected potential is larger, the bit is set to 1. Next, this "2
Then, the potential is compared with the potential at the position obtained by adding "1 of 2" corresponding to the bit on the right side of the MSB to the "1 of 1" position. If the detected potential is larger, the bit is set to 1. In this way, the potential at the position to which the magnitude (“1 to the power of 2”) corresponding to the bit on the right side is sequentially added is compared up to the bit corresponding to the LSB and detected in the process of this comparison. If it is smaller than the potential, the bit at that time is set to 1, and if it is larger than the detected potential, the bit at that time is set to 0.

This means that when the comparison result is small, the value of the detected potential has not yet been reached, and when the comparison result is large, the value exceeds the potential. Then, the extracted potential is smaller than the detected potential and close to that potential within the range of maximum resolution is extracted, and the result is 1 or 0 depending on each comparison judgment result from MSB to LSB. Is obtained as a set binary number, which corresponds to the specified coordinate position.

Step 7 is to execute the principle of the calculation process for specifying the pressed point on the touch panel described above.
(S7), step 8 (S8), step 9 (S9) and step 10 (S10).

In step 7 (S7), (DET1-D
The potential gradient of the effective area on the touch panel is obtained by ET2), and the potential obtained by multiplying the value by "1 to the power of 2" (which is the relative potential in the potential gradient) and the potential of the minimum DET2 stored value are added. The electric potential (becomes an absolute electric potential) is compared with DET0 which is a detection electric potential.

If the detected potential is larger (No judgment)
With αX (i) corresponding to the bit set to 1, and if the detected potential is smaller (Yes determination), αX (i) corresponding to the bit is set to 0 in step 8 (S8). Then, the determination in step 9 (S9) is bypassed with No, the process proceeds to step 10 (S10), the next bit position (smaller resolution) is set, and the same processing is performed until the maximum resolution bit value is reached. Perform S9) until Yes.

In this case, if all 10 bits are determined from the MSB, step 9 (S9) is skipped and it is known that the position specification of the X coordinate axis is completed. Then, in order to move to the process for specifying the position on the Y coordinate axis, the switching contact xy26 is restored in step 11 (S11), and the electrodes YU 110 and YD of the transparent resistance film B11 are restored.
A voltage is applied to 111 in the Y coordinate axis direction.

Similar to the description of the position specification on the X coordinate axis, the potential on the Y coordinate axis of the pressed point on the touch panel is detected by the voltage follower circuit 23 corresponding to the electrode XR 100 on the X coordinate axis and output as DET1. ,
It is extracted in step 12 (S12), and thereafter, the same processing as that until step 5 (S5) to step 9 (S9) in the description of the position specifying processing on the X coordinate axis is completed in Yes and the processing on the coordinate axis is ended To step 13
The process from (S13) to step 17 (S17) is repeated until Yes.

By skipping Step 17 (S17) with Yes, the position specifying processing on the Y coordinate axis is completed, and at Step 19 (S19), 1 or 0 is set to each bit as a result of the above processing for each coordinate axis. These values are output as the specified positions of the X coordinate axis and the Y coordinate axis, respectively.

[0048]

As described above, the resistive film contact type touch panel control device according to the present invention successively measures the potential serving as the reference for determination every time the position is detected, and resolves it to the effective area on the touch panel. Even if the resistance value of the resistance film of the panel or the resistance value of the internal resistance of the voltage application power source fluctuates due to secular change or environmental change, the coordinate position can be accurately specified. Furthermore, instead of simultaneously energizing each coordinate axis, by alternately and energizing in synchronization with the coordinate axis to be measured, the pressing position can be specified. It has the significant advantage that a device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a resistive film contact type touch panel control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of identifying a pressed position of the resistive film contact type touch panel control device according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Resistive film contact type touch panel 2 Touch panel control device 10, 11 Transparent resistive film 20 Potential detection part 21 Memory calculation part 22, 23, 24, 25 Voltage follower circuit 26 Switching contact 27 Internal resistance of voltage application power supply 28 Voltage application power supply 100, 101 , 110, 111 electrodes 210 CPU 211 RAM 212 ROM

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoko Yaoya 5-7-1 Shiba, Minato-ku, Tokyo NEC Electric Co., Ltd. (72) Inventor Takemasa Takahashi 5-7-1 Shiba, Minato-ku, Tokyo NEC Incorporated (72) Inventor Masatoshi Mizobe 5-7-1, Shiba, Minato-ku, Tokyo NEC Corporation (72) Inventor Chizuko Yoshida 5-7-1, Shiba, Minato-ku, Tokyo NEC (72) Inventor Hiromi Atsuta 5-7-1, Shiba, Minato-ku, Tokyo, NEC Corporation (56) Reference JP-A-4-337819 (JP, A)

Claims (3)

(57) [Claims] 1. Two resistance films having a linear resistance value are superposed with a spacer interposed therebetween, one resistance film at both ends in the X coordinate axis direction, and the other resistance film at both ends in the Y coordinate axis direction. Each of them is provided with an electrode, and the two resistance films do not come into contact with each other when the resistance film surface is not pressed, and the two resistance films come into contact with each other at the pressing point when pressed. in the resistance film contact touch panel control device for specifying a coordinate position, which is connected to each electrode, and the electrode voltage detecting means for detecting a potential of the electrode, the voltage source for supplying a voltage applied between the electrodes, Switching means for selectively switching the voltage application between the electrodes for each of the coordinate axes; analog / digital conversion means for converting an analog potential detected by the electrode potential detecting means into a digital value; Storage operation means for performing an operation on the basis of the digitally converted potential information of each electrode input from the analog / digital conversion means to specify the coordinate position of the pressing point of the resistive film contact type touch panel, and the storage operation Means, for each of the coordinate axes in the state where the resistive film surface is not pressed ,
A voltage is supplied from the voltage applying power source to supply a current to the resistive film.
In the flowing state, the electrodes are provided on both ends of the resistance film.
The maximum voltage and the minimum voltage are periodically measured, and the values are updated and stored.When the resistive film surface is pressed, the stored maximum voltage and minimum voltage in the coordinate axis direction to which the voltage is applied are stored. The potential gradient is obtained from the difference, the potential gradient is equally divided by the number of quantization steps of the analog / digital conversion means, and potential information based on the equally divided potential and the detected potential in the coordinate axis direction corresponding to the pressing point A resistor characterized in that the coordinate position in the coordinate axis direction is specified by sequentially comparing it with the value, and then the voltage applying coordinate axis is changed by the switching means and the coordinate position in the other coordinate axis direction is specified by the same means. Membrane contact type touch panel control device. 2. The electric potential in the coordinate axis direction corresponding to a pressing point in the coordinate axis direction to which a voltage is applied is detected by the electrode potential detecting means on the coordinate axis orthogonal to the coordinate axis. The resistive film contact type touch panel control device described. 3. The storage operation means represents the number of quantization steps of the analog / digital conversion means as a binary number, and sequentially adds the potentials corresponding to the bits from the leftmost end to the rightmost end of the binary number. While comparing the magnitude with the detected potential of the pressing point, the coordinate position is specified by setting the bit to 1 when it is smaller than the detected potential of the pressing point and setting it to 0 when it is large. The resistive film contact type touch panel control device according to claim 1.