JPH0225530B2 - - 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 into digital values using an AD converter and outputs the converted values 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 such a coordinate detection device, the position of the pressing point of the pressing body is obtained in an analog manner as a potential signal at the contact point of both resistive films, so this analog potential signal is converted into digital coordinate data. Requires an AD converter. And the input of the AD converter in this case is
An integrating circuit including a capacitor is usually added to remove ripple components and noise components contained in the potential signal input and convert the average value of the potential signal input into a digital value.

However, in the past, the potential signal at the pressure point position is transmitted through the voltage application electrode of the resistive film on the side to which the driving voltage is not applied while the driving voltage is applied to one of the resistive films.
Since it is configured to be directly input to the AD converter, the drive voltage is applied to the input of the AD converter on the drive voltage application side at the timing of drive voltage application. Therefore, a zero or positive drive voltage is applied to the capacitor of the integrating circuit attached to the input of the AD converter each time the drive voltage is applied, and the potential signal to be converted is input. At this timing, the capacitor must be charged or discharged according to the value of this potential signal. For this reason, the analog-to-digital conversion operation is delayed by the time required for charging or discharging, resulting in a drawback that it becomes impossible to follow the movement of the pressing point.

The present invention was made in order to solve these drawbacks, and its purpose is to eliminate the delay in analog-to-digital conversion operation and to output coordinate data that accurately follows the movement of the pressing point. The object of the present invention is to provide a detection device.

For this purpose, the present invention provides a switch means at the input of an integrating circuit connected to each input of the two AD converters, and controls the opening and closing of this switch means by a control signal for alternately applying the drive voltage, and This is configured to prevent the driving voltage from being directly input to the integrating circuit.

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

In the following embodiments, two resistive films 1 are used as objects to be pressed, for example, as shown in FIG. 1a.
and 2 are placed opposite to each other with dot-like spacers 3 arranged in the vertical and horizontal directions at predetermined intervals, and by pressing one of the resistive films, both resistive films are separated by the spacers 3 as shown in the cross-sectional view of FIG. 1b. A structure that allows point contact to be made in the absent area 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 the positive drive voltage (+V1) through transistor _Q1
one electrode 1B is connected to transistor Q ₂
connected to ground potential via. Further, the electrode 2A of the second resistive film 2 is connected to a positive drive voltage (+V1) via a transistor _Q3 , and the one electrode 2B is connected to ground potential via a transistor _Q4 .

These transistors Q ₁ to _{Q 4} are configured so that conduction and non-conduction are controlled by signals YD and XD for alternate application of drive voltages output from the output terminal Q of the flip-flop FF ₁ , respectively.

The flip-flop _FF1 is used to alternately switch the application of driving voltage to the two resistive films 1 and 2, 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 select signal by the inverter INV1 is inputted to the clock input terminal (CK).

Therefore, when the flip-flop _FF1 is input with the channel switching signal CHS of logic "1",
When a logic "0" chip select signal is generated from the processor unit PU, a logic "1" signal YD and a logic "0" signal XD are generated after the falling timing of this chip select signal.
Output. That is, when the flip-flop FF ₁ receives the channel switching signal CHS of logic "1" and generates the chip select signal of logic "0", the flip-flop FF 1 conducts the transistors Q ₃ and Q ₄ and drives the second resistive film 2. A voltage V ₁ is applied to output a signal that generates a potential gradient in the y-axis direction indicated by the arrow.

On the other hand, when the flip-flop FF ₁ 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
FF ₁ receives the channel switching signal CHS of logic "0" and the chip select signal of logic "0".
When CS occurs, transistors Q ₁ and Q ₂ are made conductive, driving voltage V ₁ is applied to the first resistive film 1,
A signal is output that generates a potential gradient in the x-axis direction indicated 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 and VX at levels corresponding to the coordinate positions of the press point in the y- and x-axis directions taken out in this way are input to integration circuits ITG ₁ and ITG ₂ via switches SW ₁ and SW _2, respectively. .

Here, the two resistive films 1 and 2 have a driving voltage V ₁
are applied alternately, the integration circuit ITG ₁ ,
The ground potential is directly applied to ITG ₂ , which slows down the integration operation and, in turn, slows down the conversion speed of potential signals VY and VX into digital values. Switches SW ₁ and SW ₂ are provided to prevent this.
In other words, in this type of coordinate detection device, the potential signal
An integrating circuit including a capacitor is added to the input stage of the AD converter to remove ripple and noise components contained in VY and VX and convert the average value of the potential signals VY and VX into digital values. Although it is generally done, in such a configuration, if the ground potential on the drive voltage application side is directly input to the integrating circuit ITG ₁ or ITG ₂ , the capacitor C of these integrating circuits will be discharged by the input of the ground potential. The potential signal extracted from each resistive film
When integrating VY and VX, charging must be restarted from ground potential. Therefore, the integration operation is delayed by the time required to charge from the ground potential to the level of the potential signals VY and VX, and the speed of conversion to coordinate data is slowed down.

For this purpose, switch SW ₁ is a flip-flop
When the output signal YD of FF ₁ is “1” and the inverter
Only when the chip select signal CS output from INV ₁ is "1", it is turned on (closed state) by the output signal of AND gate AG ₁ , and the first resistive film 1
When the driving voltage _V1 is applied to the integrator circuit ITG1, it is in an off state, and the ground potential is controlled so as not to be applied directly to the input of the integrating circuit _ITG1 . Also, switch
SW ₂ is turned on (closed state) by the output signal of AND gate AG ₁ only when the output signal XD of flip-flop FF ₁ is "1" and the chip select signal CS is "1", and SW 2 is turned on (closed state) by the output signal of AND gate AG 1. When the driving voltage V ₁ is applied to the membrane 2, it is in an off state, and the ground potential is controlled so as not to be applied directly to the input of the integrating circuit ITG ₂ .

This allows the integrator circuit including capacitor C to
ITG ₁ and ITG ₂ integrate the potential signals VY and VX only during the generation period of the chip select signal CS, and apply the integrated value to the new potential signals VY and VX at the timing when the next chip select signal CS is generated. It will now be held until In this case, since the rate of change in the levels of the potential signals VY and VX is relatively small during normal pressing operations, the integration circuits ITG ₁ ,
Capacitor C in ITG ₂ 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 ITG ₁ and ITG ₂ in this way are applied to an AD converter having two channels of AD conversion inputs CH1 and CH2.
Input to 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 AD conversion input CH2 of the second channel selects the input potential signal VX', and after the chip select signal becomes "1" signal, converts this signal VX' 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 EOC is
Inverted by INV ₂ to processor unit PU
sent to. Then, upon receiving the signal EOC, the processor unit PU 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 ₂ .
Pressure detection signal of logic “0” from output terminal Q of
This is done when SNS is input.

That is, when the driving voltage V ₁ is applied alternately to the two resistive films 1 and 2, when a pressing operation is started at an arbitrary timing, the position of the pressing point is changed to the potential signals VY, VX corresponding to the pressing operation. Of these, signal VX is input to integrating circuit ITG ₂ via switch SW ₂ , while resistor R ₁ and
The voltage is divided by _R2 and input to the base of 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" output 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 logic "0" signal is output from the output terminal Q. Pressure detection 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 determination.

By the way, when detecting that the resistive film is pressed, if a relatively large current is applied to the resistive film 1 by applying the driving voltage _V1 , the potential gradient in the resistive film 1 becomes steep, and the pressure 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. That is, the transistor Q ₂ is made non-conductive by the output signal (“0” signal) of the transistor Q ₆ , and only the positive potential of the driving voltage V ₁ is applied to the resistive film 1 by the transistor Q ₁ , and this resistor is turned off. The overall potential of the membrane 1 is shifted to the positive potential side. By this, the transistor is connected to the resistive film 1.
It is configured to flow a minute current determined by the impedance on the input side of Q ₅ and the integrating circuit ITG ₂ and the resistance value of the resistive film 1. In this case, the signal that makes transistor _Q6 conductive is the AD converter
The conversion end signal EOC of the ADC is used. As can be understood, after the conversion operation is completed, the AD converter ADC is in a state of waiting for a new potential signal VY or VX to be input, so this conversion end signal is inverted by the inverter INV ₂ . If you control transistor _Q6 using
After the conversion operation is completed, 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 is obtained no matter where the pressing is performed, and the transistor _Q5
Even if the discrimination level in is made a little high, transistor _Q5 is surely conductive. 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 FF ₁ 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 V ₁ is applied to the first resistive film 1. Furthermore, when the signal XD becomes a "1" signal, a "1" signal is output from the AND gate AG ₂ during the generation period of the chip select signal, and the switch SW ₂ is turned on as shown in FIG. . However, at this time, since no pressing operation has been performed yet, 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”,
Switch SW ₂ is turned on. At the same time, the AD converter ADC starts the conversion operation. However, at this time, the potential signal VX' to be converted is not input, so at time _t3 , a conversion end signal of logic "0" is output, and all "0" is output.
The coordinate data Y of is output. At this time _t3 , the conversion end signal becomes "0", so that the transistor _Q6 becomes conductive, and the transistor _Q2 , which had been conductive due to the signal XD, becomes non-conductive. This results in
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 shifts to the positive potential side during the generation period of the conversion end signal, as shown in FIG. 3f. Shifted.

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. 3g, and the resistor _R1
to the base of transistor _Q5 .
As a result, a signal SNSA as shown in FIG. 3h is output from the collector output of transistor _Q5 . After this, at time t ₄ , the chip select signal
When CS changes to a "0" signal, the signal SNSA is taken into the flip-flop FF2 at this falling timing, and outputted from the flip-flop _FF2 as a press detection signal SNS as shown in FIG. 3i. This causes the processor unit PU to start a program for reading the coordinates of the pressed point.

On the other hand, the pressing operation is started at time _t34 ,
In addition, since 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 integration circuit ITG ₂ . This results in
The integration circuit ITG ₂ integrates the input signal VX from t ₄ to _{t 5} , outputs a potential signal VX' as shown in FIG. 3j, and supplies it to the AD conversion input CH2 of the second channel of the AD converter ADC. . Then, the AD converter ADC
selects the potential signal VX' supplied to the AD conversion input of the second channel on the condition that the channel switching signal CHS is "1", and determines the time when the chip select signal returns to "1" signal. t ₅
The conversion operation of this potential signal VX' into a digital value is started at the timing of . When the conversion operation ends at time _t6 after a certain period of time, the conversion end signal is set to "0" to notify the processor unit PU that the conversion operation has ended. This allows the processor unit PU to
The conversion output of the converter ADC, that is, the x-axis coordinate data X is read.

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 V ₁ from the first resistive film 1 to the second resistive film 2 at the next time t ₇ . Therefore, when the chip select signal changes to a "0" signal at time _t7 , the output signal YD of the flip-flop FF ₁ changes to a "1" signal at this falling timing, and one output signal XD changes to a "0" signal. Changes to As a result, the driving voltage V ₁ is now applied to the second resistive film 2. At the same time, the switch _SW1 is turned on from time _t7 to _t8 when the chip select signal is generated. Therefore, the potential signal VY corresponding to the pressing point in the y-axis direction taken out from the electrode 1B of the first resistive film 1 is input to the integrating circuit ITG ₁ via this switch SW ₁ . Then, the integrating circuit
ITG ₁ integrates this input potential signal VY while the chip select signal is generated, and outputs the integrated signal.
The AD converter maintains VY′ even after the signal generation has stopped.
It is supplied to the AD conversion input CH1 of the first channel of the ADC. As a result, the signal at time t ₈ to _{t 9}
VY′ is converted to a digital value. 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 Figure 4 is constructed on the premise that the locus of the press point will be displayed on the screen of the display device based on the finally obtained coordinate data, so the locus of the press 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, the process moves to trajectory display processing.

In the trajectory display process, first in step 101, the flag FLG is set to "OH". 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.
Once the flag FLG has been set, the process proceeds to the "CALL SENSE" routine shown in step 102.

The "CALL SENSE" routine uses the pressure detection signal
This is to determine whether the SNS has become "0", and first, the signal is detected as shown in the next step 1020.
It is determined whether SNS is "0" or not. If the pressure detection signal SNS is
If the signal is “0”, proceed to the next step 103.
Proceed to the “CALL DATE READ” routine of
The x-axis and y-axis coordinate data X, Y are read from the AD converter ADC and stored in a first register built in the arithmetic processing unit CPU. Thereafter, 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 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 trajectory for the first read coordinate data X, Y, this first coordinate data is set as the base point and target point of the trajectory.

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, the pressure detection signal
If SNS is “0”, “CALL” in step 105 is executed to read the coordinate data X, Y of the next pressing point.
Move to the "DATA READ" routine. Then, in step 1050, new x-axis coordinate data X is read, then in step 1051, y-axis coordinate data Y is read, and these coordinate data
Store it in the register.

Next, when reading of the second coordinate data is completed, the process advances to step 106, where it is determined whether the flag FLG is "OH". 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 "OH", 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, step 107 is performed.
From there, go to step 102 and press “CALL SENSE” again.
Perform routine processing. In this case, the second
The coordinate data X′ stored in the register of
Y' is invalidated, and the coordinate data X, Y read second and stored in the first register is processed as the first coordinate data. In other words, if the deviation between the previously read coordinate data X', Y' and the newly read coordinate data X, Y on the same coordinate axis is "5H" or more, the previously read coordinate data X', Y' is regarded as discontinuous data due to fluctuations in pressing strength, etc., and in step 1030, the latest coordinate data X, Y stored in the first register is replaced with the previously read coordinate data X' , Y' in the second register.

However, as a result of the determination in step 107, if the deviation between the first read coordinate data X', Y' and the second read coordinate data X, Y is less than "5H", these data are assumed to be continuous, and proceed to the next step 108, where the coordinate data X′,
Y' is transformed to correspond to pixel coordinates on the screen of the display device. After this, step 109
In step 111, the flag FLG is set to "80H", and in step 111, the coordinate data X, Y (stored in the first register) is converted to correspond to the pixel coordinates on the screen of the display device. Then, in the next step 112, the data CX', CY' and CX, CY converted to pixel coordinates are output to the output register.
Transferred to RG3 and RG4. After this, proceed to step 113 and press “CALL LINE” here.
The routine is executed and data CX′, CY′ and data
The pixels at the coordinate positions indicated by CX and CY are connected by straight lines 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 process moves to a state where the third coordinate data is read, and the "CALL SENSE" routine of step 104 is executed again. And the press detection signal
If SNS is “0”, step 105 “CALL
DATA READ” routine is executed and steps are taken.
At 1050 and 1051, the third new coordinate data X, Y is read.

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

Next, in step 106, it is determined whether the flag FLG is "OH". At this time,
Since the flag FLG is set to "80H" in step 115, the process advances to the next step 110, and this time the deviation between the second coordinate data X', Y' and the third coordinate data X, Y is determined. It is determined whether the value is “5H” or more. 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 so, the process advances from step 110 to step 116, where it is determined whether the flag FLG is greater than "81H". At this time, since the flag FLG is "80H", the process advances to step 117, where the contents of the flag FLG are incremented. That is, the flag FLG is updated to "81H" in step 117. After this, step
The process returns to step 104 without passing through 1030, and the "CALL SENSE" routine is executed again. Then, in step 105, the fourth coordinate data X, Y is read. Then step
106 to step 110, where the coordinate data X',
It is determined whether the deviation between Y' and the coordinate data X, Y stored in the first register is "5H" or more. In other words, here we return directly to the "CALL SENSE" routine from step 117, so
The storage contents of the second register have not been updated, and the second coordinate data is stored as the true value of the previously read coordinate data. For this reason, the steps
For 110, the second read coordinate data
It is determined whether the deviation between X', Y' and the fourth newly read coordinate data X, Y is greater than "5H".

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 and the fourth step is performed.
The conversion of the coordinate data X, Y into pixel coordinates is executed and displayed as a trajectory in the same manner as in the above case. Therefore, in this case, the third coordinate data is invalid.

However, as a result of the determination in step 110, the deviation of the second and fourth coordinate data is again “5H”.
If this is the case, the process returns to step 116, where 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 and here "FLG=
It is incremented to “82H”. Thereafter, as in the case described above, after steps 104 and 105 are performed, the fifth step is performed in steps 1050 and 1051.
The th coordinate data X, Y is read and stored in the first register.

Then, the process proceeds to step 110 via step 106, and again the coordinate data X, Y stored in the first register (that is, the fifth coordinate data)
and the coordinate data stored in the second register
It is determined whether the deviation from X' and Y' (that is, the second coordinate data) is "5H" or more.

As a result of this determination, if the difference between the two is "5H" or more, the process advances to step 116 and the flag FLG is determined again. At this time, since the flag FLG has already been 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, and then in step 110, the fifth coordinate data X',
It is determined whether the deviation between Y' and the sixth coordinate data X, Y is greater than or equal to "5H". As a result of this determination, if the deviation is less than "5H", the sixth read coordinate data X, Y is converted into pixel coordinates in step 111, and the locus is displayed in the same manner as in the previous case. It will be done. In this case, since the pixel coordinates corresponding to the second pressing point are stored in the third register RG3, the pixel coordinates corresponding to the second pressing point and the pixel coordinates corresponding to the sixth pressing point The coordinates will be connected by a straight line. In other words, “5H” for the coordinate data that was the true value last time.
If the coordinate data with the above deviation occurs three times in a row, the next coordinate data is determined as the true value and output for displaying the locus.

In this way, even if continuity with the previous coordinate data is denied in step 110,
If this occurs n times in a row, the (n+1)th coordinate data is output as correct, which prevents the coordinate data from being dropped when the range of change in the pressed point coordinates is large, and allows you to faithfully follow the movement of the pressed point. The tracked trajectory can be displayed.

Now, the pressing operation is not necessarily performed continuously in time, but may be performed at certain time intervals. In such a case, unless it is determined whether the first pressing operation is continuous, the loci of the pressing points resulting from two independent pressing operations will be continuous.

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

That is, in step 1020, the pressure detection signal is
It is determined whether SNS is “0” or not, but the signal SNS
If it 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, the signal
It is determined again whether or not SNS is "0", and if it is not "0", the process proceeds to the next step 1023, where it is determined whether the soft timer value TMD is "0", that is, whether a predetermined time has elapsed. Determine. 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 the process returns to step 1022.
Then, in this step 1022, the signal is
Determine whether SNS is “0” or not. If the signal SNS is "0" at this stage, it is assumed that no pressing operation has been performed and the step is continued.
The process of 1023→1024→1022 is repeated, and during this repetition, the value TMD of the soft timer is decremented by "1". As a result, if the value TMD of the soft timer becomes "0", 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 step
“CALL DATA” from step 1022 to step 103
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 the reading of the coordinate data X, Y for the next pressing operation is flagged.
You can start it after setting FLG to “OH”. As a result of this, the 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 provides a switch means at the input of an integrating circuit connected to each input of two AD converters, controls the opening and closing of this switch means by a control signal for alternately applying a drive voltage, and It is configured to prevent the driving voltage from being linearly input to the integrating circuit on the application side.

Therefore, delays in analog-to-digital conversion operations can be eliminated, and coordinate data that accurately follows the movement of the pressing point can be output.

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, FF ₁ , FF ₂ ...Flip-flop, AG ₁ , AG ₂ ...And gate, SW ₁ ,
SW ₂ ... Switch, Q ₁ ~ _{Q 6} ... Transistor,
ITG ₁ , ITG ₂ ...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, a driving voltage is applied alternately to these resistive films, and a potential signal at a contact point between both resistive films due to pressing of one of the resistive films is changed to the driving voltage. Coordinate detection that alternately inputs the driving voltage of the resistive film on the application side to two AD converters via the application electrode and the integration circuit, converts the potential signal of the contact point into a digital value, and outputs it as coordinate data of the pressed point. In the apparatus, a switch means is provided at the input of the integrating circuit connected to each input of the two AD converters, and the opening and closing of the switch means is controlled by the control signal for alternately applying the drive voltage, so that the integrating circuit on the side to which the drive voltage is applied is controlled. A coordinate detection device characterized in that it is configured to prevent a drive voltage from being directly input to the coordinate detection device.