JPH0225528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate detection device that detects the position of a pressed point on a pressed object and outputs coordinate data on the X-axis and Y-axis indicating the pressed point position, and in particular, Using two resistive films arranged opposite to each other, a driving voltage is applied alternately to the two resistive films, and the potential signal at the contact point of both resistive films due to the pressing operation is detected as an analog quantity. This invention relates to a coordinate detection device that converts the data into digital values using an AD converter and outputs the data as coordinate data of a pressed point.

Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 11580/1983, one of two resistive films placed facing each other with a frame-shaped spacer in between is pressed to bring the two resistive films into contact with each other. 2. Description of the Related Art A coordinate detection device is known that obtains the coordinates of a pressing point of a pressing body such as a writing instrument by detecting the electric potential at the contact point, and thereby inputs handwritten characters, figures, etc. into a computer.

By the way, in this type of coordinate detection device,
When converting the potential signal at the contact point of both resistive films due to the pressing operation into digital coordinate data, the fact that one resistive film is pressed is detected by identifying the level of the potential signal, and based on this detection signal. The method of activating a program that controls the operation of an AD converter, etc. is convenient in that a microcomputer or the like is used as a control means for the entire device.

However, conventionally, to detect that a resistive film is pressed, a driving voltage is applied to one resistive film to flow a relatively large current, and a potential signal at the contact point of both resistive films is extracted from the other resistive film. ,
This is done by identifying the level of the extracted potential signal. For this reason, the level of the potential signal changes significantly depending on the position of the pressing point, and depending on how the discrimination level is determined, a detection signal indicating that a pressing operation has been performed may not be generated. The drawback was that it was not possible to obtain coordinate data that accurately followed movement.

The present invention was made to solve these drawbacks, and its purpose is to reliably detect that a pressing operation has been performed regardless of the position of the pressing point, and to obtain coordinates that accurately follow the movement of the pressing point. An object of the present invention is to provide a coordinate detection device capable of outputting data.

To this end, the present invention shifts the potential of the entire resistive film to a high potential side before the start of the pressing operation is detected, and flows a minute current through the resistive film to maintain a high level potential regardless of the position of the pressing point. This is so that a signal can be obtained.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

In the following examples, two resistive films 1 and 2 are used as objects to be pressed, as shown in FIG. 1a.
are arranged opposite to each other with dot-like spacers 3 arranged vertically and horizontally at predetermined intervals, and by pressing one of the resistive films, both resistive films can be separated without the spacer 3, as shown in the cross-sectional view of FIG. 1b. A structure that allows point contact at certain parts shall be used.

FIG. 2 is a block diagram showing one embodiment of the present invention. In the figure, an electrode 1A of the first resistive film 1
is a positive drive voltage +V1 via transistor Q1
and one electrode 1B is connected to transistor Q2.
connected to ground potential via. Further, the electrode 2A of the second resistive film 2 is connected to the positive drive voltage +V1 via the transistor Q3, and the one electrode 2B is connected to the ground potential via the transistor Q4.

These transistors Q1 to Q4 are connected to output terminals Q of flip-flop FF1 and signals YD and 3 for alternately applying drive voltages, respectively, which are output from the output terminal Q of flip-flop FF1.
It is configured so that conduction and non-conduction are controlled by XD.

Flip-flop FF1 has two resistive films 1 and 2.
This is for alternately switching the application of the driving voltage to the circuit, and is constituted by a D-type flip-flop. A channel switching signal CHS is inputted from the processor unit PU to the data input terminal D, and a signal CS obtained by inverting the chip selector signal by the inverter INV1 is inputted to the clock input terminal CK.

Therefore, flip-flop FF1 is logic "1"
When a logic "0" chip select signal is generated from the processor unit PU while the channel switching signal CHS is being input, the logic "1" signal YD and logic “0” signal
Output XD. That is, flip-flop FF
1 indicates that the channel switching signal CHS of logic "1" is input and the chip select signal of logic "0"
When CS occurs, transistors Q3 and Q4
is made conductive, a driving voltage V1 for the second resistive film 2 is applied, and a signal is output that generates a potential gradient in the y-axis direction shown by the arrow.

On the other hand, when the flip-flop FF1 receives the channel switching signal CHS of logic "0",
When a logic "0" channel select signal is generated from the processor unit PU, a logic "0" signal YD and a logic "1" signal XD are output after the fall timing of this chip select signal. That is, flip-flop
FF1 receives the channel switching signal CHS of logic "0" and the chip select signal of logic "0".
When CS occurs, transistors Q1 and Q2
is made conductive, a driving voltage V1 is applied to the first resistive film 1, and a signal is output that generates a potential gradient in the x-axis direction shown by the arrow.

Therefore, by alternately switching the channel switching signal CHS sent from the processor unit PU between logic "1" and logic "0", the x-axis direction of the first resistive film 1 and the y-axis direction of the second resistive film A predetermined potential gradient can be generated alternately in the axial direction. As a result, if one resistive film is pressed at an arbitrary coordinate position and both resistive films are brought into point contact, when a potential gradient is generated in the y-axis direction, the position of the pressed point in the y-axis direction is changed between the two resistive films. Through the contact point and the electrode 1B of one of the resistive films 1, it can be taken out as a potential signal VY at a level corresponding to the pressed point position in the y-axis direction.On the other hand, when a potential gradient is generated in the x-axis direction, The position of the pressing point in the x-axis direction can be extracted as a potential signal VX at a level corresponding to the pressing point position in the x-axis direction via the contact point between both resistive films and the electrode 2B of one of the resistive films 2.

The potential signals VY, VX of the levels corresponding to the coordinate positions of the pressed point in the y-axis and x-axis directions taken out in this way are input to the integrating circuits ITG1, ITG2 via switches SW1, SW2, respectively.

Here, the two resistive films 1 and 2 are connected to a driving voltage V1
is applied alternately, the integration circuit ITG
1. The ground potential is directly applied to ITG2, which slows down the integration operation and, in turn, slows down the conversion speed of potential signals VY and VX into digital values. To prevent this, switches SW1 and SW2 are provided. In other words, in this type of coordinate detection device, the input stage of the AD converter removes ripple components and noise components contained in the potential signals VY and VX, and converts the average value of the potential signals VY and VX into a digital value. It is common practice to add an integrating circuit including a capacitor to the
If it is directly input to ITG1 or ITG2, the capacitor C of these integrating circuits will be discharged by the input of the ground potential, and during the operation of integrating the potential signals VY and VX taken out from each resistor film, the capacitor C of these integrating circuits will not be charged from the ground potential. I have to start it again. Therefore, the potential signal VY,
The integration operation is delayed by the time it takes to charge to the VX level, slowing down the conversion speed to coordinate data.

For this reason, the switch SW1 is activated when the output signal YD of the flip-flop FF1 is "1" and the chip select signal CS output from the inverter INV1.
It is turned on (closed state) by the output signal of the AND gate AG1 only when it is "1", and it is turned off when the driving voltage V1 is applied to the first resistive film 1, and the ground potential is connected to the integrating circuit. It is controlled so that it does not directly apply to the input of ITG1. In addition, switch SW2 outputs the output signal XD of flip-flop FF1.
is “1” and the chip select signal CS is “1”
It is turned on (closed state) by the output signal of the AND gate AG1 only when It is controlled so that it does not directly participate.

This allows the integrator circuit ITG containing capacitor C to
1. ITG2 integrates the potential signals VY and VX only during the generation period of the chip select signal CS, and applies the integrated value to the new potential signals VY and VX at the timing of the generation of the next chip select signal CS. It will hold up to. In this case, since the rate of change in the level of the potential signals VY and VX is relatively small in normal pressing operations, the integration circuit ITG1,
Capacitor C in ITG2 is instantly charged to the level of new potential signals VY and VX,
The integral operation can be completed extremely quickly.

The potential signals VY' and VX' integrated in the integrating circuits ITG1 and ITG2 in this way have two channels of AD conversion inputs CH1 and CH2.
Input to AD converter ADC.

AD converter ADC uses channel switching signal CHS
When is “0”, the AD conversion input of the first channel
Select the potential signal VY′ input to CH1,
After the chip select signal becomes a "1" signal, this signal VY' is converted into a corresponding digital value. Then, when the conversion operation is completed after a certain period of time, a conversion completion signal of logic "0" is sent.
The converted value is output as y-axis coordinate data Y with a serial data structure. In addition, the channel switching signal
When CHS is "1", the potential signal VX' input to the AD conversion input CH2 of the second channel is selected, and after the chip select signal becomes "1" signal, this signal VX' is converted to the corresponding digital value. Convert. Then, the conversion value is converted to the conversion end signal.
Output as x-axis coordinate data X along with EOC.

In this case, the conversion end signal is
Inverted by INV2 to processor unit
Sent to PU. Then, the processor unit PU
Upon receiving the signal EOC, reads the x-axis and y-axis coordinate data X, Y in a serial data configuration.

Now, the processor unit PU is an arithmetic processing unit.
It is composed of a CPU, program memory MEM, etc., and performs a series of controls such as reading the coordinate data input from the AD converter ADC and determining its continuity, as coordinate data that accurately follows the movement of the pressing point. The program to perform this kind of control is started using the flip-flop FF.
Pressure detection signal of logic “0” from output terminal Q of 2
This is done when SNS is input.

That is, when the driving voltage V1 is applied alternately to the two resistive films 1 and 2, when a pressing operation is started at an arbitrary timing, potential signals VY and VX corresponding to the pressing point position are extracted. Of these, the signal VX is input to the integrating circuit ITG2 via the switch SW2, while being divided by the resistors R1 and R2 and input to the base of the transistor Q5.

Transistor Q5 becomes conductive when the pressing operation on the resistive film is started and the level of the potential signal VX exceeds a predetermined value, and a detection signal SNSA of "0" indicating that the pressing operation has started is output from its collector output.
Output. The detection signal SNSA of "0" outputted from this transistor Q5 is supplied to the data input terminal D of the D-type flip-flop FF2, and is taken in at the rising timing of the chip select signal CS, and the pressure of logic "0" is detected from the output terminal Q. signal
Output as SNS. Therefore, if the chip select signal is generated in a relatively short cycle, the pressure detection signal SNS can be obtained immediately after the pressure operation on the resistive film, and the process of reading the coordinate data X, Y and its continuity can be easily obtained. It is possible to start a program that performs processing such as discrimination.

By the way, when detecting that the resistive film is pressed, if a relatively large current is caused to flow through the resistive film 1 by applying the driving voltage V1, the potential gradient in the resistive film 1 becomes steep, and the pressing point Depending on the position of the current signal VX, the level of the current signal VX changes significantly. As a result, depending on how the identification level of transistor Q5 is determined, it may become impossible to identify that a pressing operation has been performed. Therefore, before detecting the pressing operation, a small current is passed through the resistive film 1 to make the potential gradient gentle, so that no matter where the pressing operation is pressed, a high-level potential signal is generated.
Make sure you get VX. In other words, the transistor Q2 is connected to the output signal of the transistor Q6 (“0”
The transistor Q1 applies only the positive potential of the drive voltage V1 to the resistive film 1 to shift the overall potential of the resistive film 1 to the positive potential side. This allows a small current determined by the impedance of the input side of the transistor Q5 and the integrating circuit ITG2 and the resistance value of the resistive film 1 to flow through the resistive film 1. in this case,
The signal that turns on the transistor Q6 is:
The conversion end signal EOC of the AD converter ADC is used. As can be understood, the AD converter ADC generates a new potential signal VY or
It will be in a state of waiting for VX to be input, so
If this conversion end signal is inverted by the inverter INV2 to control the transistor Q6, the resistive film 1
is always shifted to the positive potential side. Therefore, if a pressing operation is performed in this state, a high-level potential signal VX will be obtained no matter where the pressure is applied, and even if the discrimination level of transistor Q5 is set slightly high, transistor Q5 will surely become conductive. do. In other words, it is possible to reliably detect that a pressing operation has been performed. As a result, the program in the processor unit can be reliably started following the pressing operation. In this case, since the discrimination level of the transistor Q5 can be set to a high value, it is possible to prevent an erroneous press detection signal SNS from being generated due to disturbance noise.

Note that since the coordinates of the pressing point are detected as a pair in the x-axis and y-axis directions, the transistor Q5 for detecting that a pressing operation has been performed is
It is sufficient to provide it only on the axial potential signal VX side.
The same applies to transistor Q6.

Here, with reference to the time chart shown in FIG. 3, the operation until the coordinate data X, Y of the x-axis and y-axis is input to the processor unit PU will be summarized.

First, at time t ₁ , when the chip select signal shown in a of the figure becomes "0", the conversion end signal (b of the same figure) becomes "1" at this falling timing.
The signal is restored and the AD converter ADC goes into a standby state. At this time, the channel switching signal CHS is
, the output signal YD of the flip-flop FF1 becomes a "0" signal as shown in the figure d, and one output signal XD becomes a "1" signal as shown in the figure e. It becomes a signal. This results in
A state is reached in which the driving voltage V1 is applied to the first resistive film 1. Further, when the signal XD becomes a "1" signal, a "1" signal is output from the AND gate AG2 during the generation period of the chip select signal, and the switch SW2 is turned on as shown in FIG. However, since the pressing operation has not yet been performed at this time, the potential signal VX does not appear on the electrode 2B of the second resistive film 2. Then, at time t ₂ ,
When the chip select signal returns to “0”,
The switch SW2 is turned off. At the same time, A.D.
The converter ADC will start the conversion operation.
However, at this time, since the potential signal VX' to be converted is not input, a conversion end signal of logic "0" is outputted at time _t3 , and coordinate data Y of all "0" is outputted. As the conversion end signal becomes “0” at this time _t3 ,
Transistor Q6 becomes conductive, and transistor Q2, which had been conductive due to signal XD, becomes non-conductive. As a result, the entire potential of the first resistive film 1 is shifted to the positive potential side, and accordingly, the signal VY taken out from the electrode 1B also becomes positive during the generation period of the conversion end signal, as shown in FIG. 3f. shifted to the potential side.

When the pressing operation is started at time _t34 in this state, a high-level potential signal VX is taken out from the electrode 2B as shown in FIG.
1 to the base of transistor Q5. As a result, a signal SNSA as shown in FIG. 3h is output from the collector output of the transistor Q5. After this, when the chip select signal changes to a "0" signal at time _t4 , the signal SNSA is taken into the flip-flop FF2 at this falling timing, and its output is used as a press detection signal SNS as shown in FIG. 3i. Output.
This causes the processor unit PU to start a program for reading the coordinates of the pressed point.

On the other hand, since the pressing operation is started at time ₃₄ and the chip select signal is generated between times _t4 and _t5 , a potential signal corresponding to the position of the pressing point in the x-axis direction is generated via switch SW2.
VX is input to the integrating circuit ITG2. As a result, the integrating circuit ITG2 integrates the input signal VX from t ₄ to _{t 5} , and generates a potential signal as shown in FIG.
It outputs VX' and supplies it to the AD conversion input CHD2 of the second channel of the AD converter ADC. Then, AD
The channel switching signal CHS of the converter ADC is “1”
of the second channel, provided that
The potential signal VX' supplied to the AD conversion input is selected, and the conversion operation of this potential signal VX' into a digital value is started at time _t5 when the chip select signal returns to the "1" signal. and,
When the conversion operation is completed at time _t6 after a certain period of time, the conversion end signal is set to a "0" signal to notify the processor unit PU that the conversion operation has ended. As a result, the processor unit PU outputs the conversion output of the AD converter ADC, that is,
Read the x-axis coordinate data X.

On the other hand, before reading the x-axis coordinate data X, the processor unit PU sets the channel switching signal CHS to "1" at time _t5 .
This is to switch the application of the drive voltage V1 from the first resistive film 1 to the second resistive film 2 at the next time _t7 . Therefore, when the chip select signal changes to a "0" signal at time _t7 , flip-flop FF1 changes at this falling timing.
The output signal YD of the two changes to a "1" signal, and one output signal XD changes to a "0" signal. As a result, the driving voltage V1 for the second resistive film 2 is now applied. At the same time, the chip select signal
The switch is activated at time t ₇ to t ₈ when CS is occurring.
SW1 is turned on. Therefore, the potential signal VY corresponding to the pressing point in the y-axis direction extracted from the electrode 1B of the first resistive film 1 is applied to this switch SW1.
The signal is input to the integrating circuit ITG1 via. Then,
Integrating circuit ITG1 integrates this input potential signal VY while the chip select signal is being generated, and holds the integrated signal VY' even after the generation of the signal stops.
AD conversion input of the first channel of AD converter ADC
Supply to CH1. As a result, the signal VY' is converted into a digital value from time t ₈ to _{t 9} . Then, upon generation of the conversion end signal, the data is read into the processor unit PU.

The above operations are repeated while the pressing operation continues. Thereby, the coordinate data of the pressed point can be obtained as a pair of x-axis and y-axis.

Next, Figure 4 shows the operation of the processor unit PU, which reads the coordinate data ZD output from the AD converter ADC, determines its continuity, and outputs it as coordinate data that faithfully follows the movement of the pressing point. This will be explained with reference to the flowchart shown in .

Note that the flowchart shown in FIG. 4 is constructed on the premise that the trajectory of the pressing point will be displayed on the screen of the display device based on the finally obtained coordinate data, so the trajectory of the pressing point will not be displayed. We will explain the operation up to this point.

In FIG. 4, first, in step 100, it is determined whether or not the setting of conditions such as the display color of the locus of the pressed point and its background color has been completed. If the various conditions for this display have been set,
Move on to trajectory display processing.

In the trajectory display process, first step 101
The flag FLG is set to "OH" at the time. The flag FLG is used to determine whether the coordinate data ZD read from the AD converter ADC is the first one at the stage of entering the trajectory display process, and is set to “OH” at the stage of entering the trajectory display process. , indicating that this is the first coordinate data.
When the setting of the flag FLG is completed, the process proceeds to the "CALL SENSE" routine shown in step 102.

The "CALL SENSE" routine uses the pressure detection signal
It is determined whether the signal SNS is "0" or not. First, as shown in the next step 1020, it is determined whether the signal SNS is "0" or not. if,
Pressure detection signal is generated by pressing operation on the resistive film.
If the SNS has become a "0" signal, proceed to the next step 103, the "CALL DATA READ" routine, read the x-axis and y-axis coordinate data X, Y from the AD converter ADC, and send it to the arithmetic processing unit CPU. It is stored in the built-in first register. After this, in steps 1030 and 1031, the currently read x-axis and y-axis coordinate data X and Y are also stored in the second register as coordinate data X' and
Store it as Y′. This means that the trajectory of the press point is set at the previously read coordinate data X, Y as the base point, the newly read current coordinate data X, Y is set as the target point, and these base points and the target point are connected with a straight line. This is because it is displayed by That is, since there is no data that should serve as the base point for displaying the locus for the first read coordinate data X, Y, this first coordinate data is set with the base point of the locus as the target point.

When the reading of the first coordinate data X, Y is completed in this way, the next step 104 is "CALL
The program moves to the "SENSE" routine, and in step 1040, it is determined again whether the press detection signal SNS has become "0". Here, if the press detection signal SNS is "0", the process moves to the "CALL DATA READ" routine of step 105 in order to read the coordinate data X, Y of the next press point. Then, in step 1050, new x-axis coordinate data X is read, and then in step 1051, y-axis coordinate data Y is read, and these coordinate data X and Y are stored in the first register.

Next, when the reading of the second coordinate data is completed, the process advances to step 106, where it is determined whether the flag FLG is "0H".
In other words, "CALL DATA" in step 103
A flag indicating whether the coordinate data X, Y read in the “READ” routine was the first one.
Distinguished by FLG. If the flag FLG is "0H", the process advances to step 107, and in this step, the coordinate data X' read first and stored in the second register, and the coordinate data X' read second and stored in the first register Find the deviation from the coordinate data Similarly, the deviation between the first coordinate data Y' and the second coordinate data Y is determined, and it is determined whether the deviation is a value of "5H" or more. As a result of this determination, if the deviation is "5H" or more, the process returns from step 107 to step 102 and the "CALL SENSE" routine is processed again. In addition,
In this case, the coordinate data X', Y' stored in the second register is invalidated, and the coordinate data X, Y' stored in the first register is read second.
Y will be treated as the first one. In other words, the previously read coordinate data X′,
If the deviation between Y' and the newly read coordinate data X, Y on the same coordinate axis is more than "5H", the previously read coordinate data X', Y' is due to fluctuations in pressing strength, etc. In step 1030, the latest coordinate data X, Y stored in the first register is stored in the second register as previously read coordinate data X', Y'. Ru.

However, as a result of the determination in step 107,
The deviation between the first read coordinate data X', Y' and the second read coordinate data X, Y is "5H"
If the coordinate data is less than
X' and Y' are transformed to correspond to pixel coordinates on the screen of the display device. After this, in step 109, the flag FLG is set to "80H",
Furthermore, in step 111, the coordinate data
(stored in the first register) are converted to correspond to pixel coordinates on the screen of the display device.
Then, in the next step 112, data CX', CY' and CX, CY converted into pixel coordinates are transferred to output registers RG3 and RG4. After this, the process proceeds to step 113, where the "CALL LINE" routine is executed and the data is
The pixels at the coordinate positions indicated by CX', CY' and the data CX, CY are connected by a straight line and displayed on the screen.

In this way, when the pixels corresponding to the two pressed points are connected by a straight line and displayed as the locus of the pressed points, next in step 114 the register RG
4 storage data CX, CY are transferred to register RG3. This is to set the pixel coordinates corresponding to the second pressed point as a new base point for trajectory display when the pixel coordinates corresponding to the third pressed point are specified.

When the processing in step 114 is completed, the flag FLG is set to "80H" in the next step 115, and then the process returns to step 1030, where the second coordinate data X stored in the first register is stored in the second register. is stored as data X'. Then, in the next step, the second coordinate data Y stored in the first register is stored in the second register as data Y'.

As a result, the state moves to the state where the third coordinate data is read, and "CALL SENSE" in step 104 is pressed.
The routine is executed again. If the press detection signal SNS is "0", the "CALL DATA READ" routine in step 105 is executed, and the third new coordinate data X, Y is read in steps 1050 and 1051.

This third new coordinate data is stored in the first register.

Next, in step 106, it is determined whether the flag FLG is "0H". At this time, since the flag FLG is set to "80H" in step 115, the process advances to the next step 110.
This time, it is determined whether the deviation between the second coordinate data X', Y' and the third coordinate data X, Y is greater than or equal to "5H". If the deviation is less than "5H", these coordinate data are considered to be continuous. Then, in step 111, the newly read third coordinate data X, Y is converted to correspond to the pixel coordinates on the screen of the display device, and then the second press The pixel coordinates corresponding to the point and the pixel coordinates corresponding to the third pressed point are connected by a straight line and displayed.

The coordinate data sequentially read in this way is displayed as a locus that follows the movement of the pressing point after the continuity of the previous and subsequent coordinate data is determined. That is, coordinate data with a deviation of less than "5H" are regarded as mutually continuous and correct (true values of coordinate data) and output to the display device.

However, as a result of the determination in step 110,
The deviation between the second coordinate data X', Y' and the third coordinate data X, Y on the same coordinate axis is "5H"
If above, step 110 to step 116
The process proceeds to step 11, where it is determined whether the flag FLG is greater than "81H". At this time, the flag
Since FLG is "80H", the process advances to step 117, where the contents of this flag FLG are incremented. That is, the flag FLG is updated to "81H" in step 117. After this, proceed to step 10 without passing through step 1030.
Returning to step 4, the "CALL SENSE" routine is executed again. Then, in step 105, the fourth coordinate data X, Y is read. Next, the process proceeds to step 110 via step 106, where the deviation between the coordinate data X', Y' stored in the second register and the coordinate data X, Y stored in the first register is determined as " 8H”
It is determined whether or not the value is greater than or equal to the value. In other words, since the process returns directly from step 117 to the "CALL SENSE" routine, the contents of the second register are not updated and the second coordinate data is stored as the true value of the previously read coordinate data. ing. Therefore, in step 110, if the deviation between the second read coordinate data X', Y' and the fourth newly read coordinate data X, Y is "5H" or more,
It will be determined whether or not.

As a result of this determination, if the deviation between the two is less than "5H", the process advances from step 110 to step 111, where the fourth coordinate data X, Y is converted into pixel coordinates, and the same process as in the previous case is performed. Displayed as a trajectory. Therefore, in this case, the third coordinate data is invalid.

However, as a result of the determination in step 110, if the deviation between the second and fourth coordinate data is again "5H" or more, the process proceeds to step 116 again.
Here, it is determined whether the flag FLG is greater than "81H". At this time, since the flag FLG is "81H", the process advances to step 117, where it is incremented to "FLG="82H". After this, as in the previous case, step 10
After the processing of step 4,105 is performed, step 10
At 50 and 1051, the fifth coordinate data X, Y is read and stored in the first register.

Then, step 11 is performed via step 106.
0, and again the coordinate data X, Y stored in the first register (i.e., the fifth coordinate data) and the coordinate data X', Y' stored in the second register (i.e., the fifth coordinate data) second coordinate data)
It is determined whether the deviation from the current value is "5H" or more.

As a result of this determination, if the deviation between the two is "5H" or more, the process advances to step 116 and the flag FLG is reset again.
A determination is made. At this time, since the flag FLG is already set to "82H", the process advances to step 118 and is set to "80H" this time. After this, the process returns to steps 1030 and 1031, and the fifth coordinate data X, Y are stored in the second register as new true values, and the processing of each step subsequent to step 104 is executed thereafter.

That is, in steps 105 to 1051, the sixth coordinate data X, Y is newly read,
Subsequently, in step 110, it is determined whether the deviation between the fifth coordinate data X', Y' and the sixth coordinate data X, Y is greater than "5H". As a result of this judgment, if the deviation is less than “5H”, proceed to step 1.
11, the sixth read coordinate data X,
Conversion to Y pixel coordinates is performed, and the locus is displayed in the same manner as in the previous case. in this case,
Since the pixel coordinates corresponding to the second press point are stored in the third register RG3, the pixel coordinates corresponding to the second press point and the pixel coordinates corresponding to the sixth press point are They will be connected by a straight line. In other words, if coordinate data with a deviation of "5H" or more occurs three times in a row from the previous coordinate data as the true value, the next coordinate data will be determined as the true value and output for displaying the trajectory. .

In this way, even if the continuity with the previous coordinate data is denied in step 110, if this continues n times, the (n+1)th coordinate data is output as correct, so that the pressed point coordinates can be changed. It is possible to prevent the coordinate data from being dropped when the range of change is large, and it is possible to display a locus that faithfully follows the movement of the pressing point.

Now, the pressing operation is not necessarily performed continuously in time, but may be performed at certain time intervals. In such cases, it is necessary to identify whether the first pressing operation is continuous or not.
The trajectory of the pressing point resulting from two independent pressing operations becomes continuous.

Therefore, this flowchart is provided with a software timer means for identifying the time interval between pressing operations.

That is, in step 1020, it is determined whether the press detection signal SNS is "0" or not.
If SNS is not "0", it is assumed that no pressing operation has been performed, and the process proceeds to step 1021, where the value TMD of the soft timer is set to "FF" (in hexadecimal notation). After this, in step 1022, it is again determined whether the signal SNS is "0" or not.
If not “0”, proceed to the next step 1023,
Here, it is determined whether the value TMD of the soft timer has become "0", that is, whether a predetermined time has elapsed. As a result of this determination, if TMD is not "0", the value of the soft timer is decremented (TMD - 1) in step 1024, and
Return to step 1022. Then, in step 1022, it is again determined whether the signal SNS is "0". And even at this stage, the signal
If SNS is "0", it is assumed that no pressing operation has been performed yet, and steps 1023→1024 are performed.
→The process of 1022 is repeated, and during this repetition, the value TMD of the soft timer is decremented by "1". As a result, the soft timer value TMD is “0”
If this happens, it is assumed that no pressing operation has been performed for a predetermined period of time, and the process returns to step 100, the initial condition determination step.

However, if the pressing operation is performed before the soft timer value TMD reaches "0", the "CALL DATE" from step 1022 to step 103 is
The program moves to the ``READ'' routine and sequentially reads the coordinate data X and Y.

Therefore, when a continuous pressing operation is performed, the coordinate data X and Y are successively read in sequence as described above. However, for two pressing operations separated by a predetermined time interval, the process returns to step 100 after the first pressing operation is completed, and reading of the coordinate data X, Y for the next pressing operation is flagged.
You can start after setting FLG to “0H”.
As a result, coordinate data X and Y for pressing operations that are temporally widely separated are output to the display device while being distinguished from each other, and can be displayed as completely independent trajectories.

This is exactly the same for steps 1040-1044.

As explained above, the present invention shifts the potential of the entire resistive film to a high potential side before the start of a pressing operation is detected, and flows a minute current through the resistive film to maintain a high potential regardless of the position of the pressing point. This makes it possible to obtain a level potential signal.

Therefore, it is possible to reliably detect that a pressing operation has been performed regardless of the position of the pressing point, and output coordinate data that accurately follows the movement of the pressing point.

In addition, in the embodiment, an object having dot-shaped spacers was used as the object to be pressed, but the object is not limited to this.

[Brief explanation of drawings]

FIG. 1 is a structural diagram showing an example of a pressed body used in the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a time chart for explaining its operation, and FIG. The figure is a flowchart up to displaying a trajectory based on coordinate data. 1, 2...Resistive film, FF1, FF2...Flip-flop, AG1, AG2...AND gate, SW
1, SW2...Switch, Q1-Q6...Transistor, ITG1, ITG2...Integrator circuit, ADC...
…AD converter, PU…processor unit,
CPU...Arithmetic processing unit, MEM...Memory.

Claims (1)

[Claims] 1. Two resistive films are arranged facing each other, and driving voltages are alternately applied to these resistive films through switching elements on the high potential side and the low potential side, and by pressing one of the resistive films. The potential signal at the contact point of both resistive films is extracted from the driving voltage application electrode of the resistive film on the side to which the driving voltage is not applied, and the start of the pressing operation is detected by identifying the level of the potential signal. In a coordinate detection device that converts into a digital value using an AD converter and outputs it as coordinate data of a pressing point, before the start of a pressing operation is detected, the switching element on the low potential side is made non-conductive and the potential of the entire resistive film is adjusted. A coordinate detection device characterized by being shifted to a high potential side. 2. The coordinate detection device according to claim 1, wherein a conversion end signal of the AD converter is used as a signal for making the switching element on the low potential side non-conductive.