JPH0450606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a coordinate data input device using a constant current type tablet.

(B) Prior Art Recently, as an input device for inputting figures or characters, a constant current type tablet coated with a resistor has been used, for example as shown in Japanese Patent Application Laid-Open No. 161535/1983. By pressing the tablet with an input pen connected to a current source, the coordinate position of the input pen is detected by detecting the current value flowing through the tablet, and the display device displays the movement trajectory of the input pen on the tablet based on the detected coordinate data. The screen is configured so that figures or characters can be input by displaying them on the screen.

Therefore, when pressing the tablet lightly with the input pen, the contact resistance at the contact point between the input pen and the tablet increases, and the specified constant current no longer flows from the input pen, making it difficult to detect the current value. Therefore, the control circuit that detects the coordinate position of the input pen cannot accurately detect the coordinate position of the input pen. As a result, the position of the input pen is displayed on the display device in a shifted position, which causes problems such as an operator feeling that the position is strange. Particularly when the tablet is made transparent and is used by placing it on a display device, the discrepancy between the position of the input pen and the display on the display device becomes obvious, which is undesirable.

Therefore, as a way to solve this problem, it is determined whether the current value flowing through the tablet is greater than or equal to a preset value, and if it is greater than or equal to the preset value, it is determined that a constant current is flowing, and the coordinate data is imported. If the current is below a certain set value, it is determined that the constant current is not flowing, and the display on the display device is stopped without importing the coordinate data, thereby changing the display when the input pen is lightly pressed. This prevents misalignment from occurring.

(c) Problems to be solved by the invention Although the above-mentioned method can prevent display deviation to some extent, since the characteristics of the resistor vary from tablet to tablet, it is necessary to determine whether the current is a preset constant current or not. Since the specific value is set to a slightly lower value with a margin in mind, it has not been possible to completely prevent display shifts.

The present invention has been made to solve this problem, and provides a coordinate data input device configured to set specific values to values optimal for the tablet.

(d) Means for Solving Problems The present invention includes a circuit that converts the current flowing into the tablet from the input pen into a voltage according to the position of the input pen, and a circuit that converts the current flowing into the tablet from the input pen into a voltage, and a predetermined voltage based on the converted voltage. A calculation means for calculating the position coordinates of the input pen by performing calculation processing, a means for storing the minimum value of the voltage converted by pressing at a plurality of places on the tablet, and a means for determining a specific value based on the determined minimum value. means for storing, means for detecting whether a predetermined constant current is flowing on the tablet based on the converted voltage and specific value, and a movement trajectory of the input pen on a display device under the control of each of the means. The control means shown in FIG.

(e) Effect By configuring the present invention as described above, the specific value is set to the optimum value that matches the characteristics of the tablet, so that the deviation between the position of the input pen and the display position on the display device can be minimized. can do.

(f) Examples Embodiments of the present invention will be described below based on the drawings.

Reference numeral 1 designates a constant current type tablet, which is constructed by coating a resistor 3 on a substrate 2, as shown in FIG.
Diodes 4, 4 for preventing backflow are placed around the resistor 3.
Current detection electrodes 5A, 5B, 5C, and 5D are provided via the current detection electrodes 5A, 5B, 5C, and 5D. Backflow prevention diode 4, 4...
acts to prevent the current once flowing out from the tablet 1 from flowing back into the resistor 3. 6 is an input pen connected to constant current source 7, and tablet 1
When pressed, the current detection electrodes 5A, 5B) 5C)
5D). 8A, 8B, 8C, 8
D indicates that the current flowing out from the current detection electrodes 5A, 5B, 5C, 5D is detected by the detection switches 9A, 9B, 9C,
A current-to-voltage conversion circuit (I/V conversion circuit) supplied through 9D generates output voltages (X ₁ ) (X ₂ ) (Y ₁ ) (Y ₂ ) according to the current value. The converted output voltages (X ₁ ) (X ₂ ) (Y ₁ ) (Y ₂ ) are input to the control circuit 10 and are input to the position coordinates (X, Y) of the input pen 6.
used for detection. In addition, detection switch 9A, 9
B, 9C, 9D are connected to the control circuit 1 so that 9A, 9B and 9C, 9D are opened and closed as a pair and operate in opposite directions.
Opening/closing is controlled by a switching signal (S) of 0.

Here, the currents (I ₁ ) (I ₂ ) (I ₃ ) (I ₄ ) flowing out from the current detection electrodes 5A, 5B, 5C, and 5D are I ₁ +I ₂
= constant, I ₃ + I ₄ = constant, so the position coordinates (X, Y) of the input pen 6 are X = X ₁ / (X ₁ + X ₂ ), Y =
The above calculation is performed based on the output voltage (X ₁ ) (X ₂ ) (Y ₁ ) (Y ₂ ) inputted to the control circuit 10, and is expressed as Y ₁ /(Y ₁ +Y ₂ ). Position coordinates (X, Y) are detected. The control circuit 10 is composed of a microprocessor and has a program memory 11.
The above calculations and other processes are performed according to a processing program stored in advance in the computer. Reference numeral 12 denotes a data memory in which data etc. processed by the control circuit 10 are stored. An image memory 13 stores image signals processed by the control circuit 10, and displays on the display device 14 based on the stored data. Note that the tablet 1 is now formed transparent and is placed on a display device 14.

Reference numeral 15 is for transmitting graphic or character data inputted from the tablet 1 to another device via a transmission line 16 such as a telephone line, or for receiving data transmitted from another device and displaying it on the display device 14. Second, it is a signal processing circuit that performs signal processing such as data modulation or demodulation.

Next, a third explanation of the operation of the present invention having such a configuration will be described.
This will be explained based on the flowcharts shown in FIGS.

First, before drawing on the tablet 1, an operation is performed to obtain a specific value. When a mote is set to require a specific value by operating a mode switch (not shown), the control circuit 10 detecting the operation of the mode switch first performs initial settings in step 301 to set data such as the minimum value, according to the program in the program memory 11. After this, in step 302, a "+" symbol marker is displayed on the display device 14 to indicate the input point, as shown in FIG. 5a. Then, when the operator presses the input pen 6 on the tablet 1 corresponding to the position where the marker is displayed, step 30
3, the control circuit 10 detects the press of the input pen 6
The process proceeds to step 304, where the detection switches 9A and 9B are closed upon generation of the switching signal (S), and the input pen 6 is closed.
Set the detection state of the X coordinate of . Detection switch 9
The current flowing in from the input pen 6 by closing A and 9B flows out from the current detection electrodes 5A and 5B, is converted into output voltages X ₁ and X ₂ by the current-to-voltage conversion circuits 8A and 8B, and is sent to the control circuit 10. Supplied. At this time, detection switches 9C and 9D are open, and the current -
Voltage conversion circuits 8C and 8D do not function. Next, the process proceeds to step 306, where the calculation of X _{1 +} It is written and set in the data memory 12 as follows. However, if the calculation result is larger than the minimum value, the minimum value is not changed and the process proceeds to step 309, where it is determined whether or not the conversion of the Y coordinate has been completed. Since the conversion of the Y coordinate has not yet been completed, step 304
Return to , open detection switches 9A and 9B, and open detection switches 9C and 9.
By closing D and performing the processing in steps 305 to 308, the Y coordinate is detected in the same manner as described above. When the detection at the coordinates of one point is completed in this way, the process proceeds to step 310, where it is determined whether or not all detections have been completed.If not, the process proceeds to step 311, where the next input position is detected. After that, the process returns to step 302, and as shown in FIG. 5B, a marker symbol indicating the next input position is displayed on the display device 14, and the same process as described above is repeated to detect the new input position.

In this way, by detecting a plurality of input positions over the entire tablet 1 as _shown in _{FIG .}
The minimum value of Y ₂ is stored. When all input positions have been detected, the control circuit 10 proceeds to step 312.
Proceed to X ₁ stored in data memory 12
Find the value by subtracting a predetermined number a from the minimum value of +X ₂ and Y ₁ +Y ₂ (X _nio , Y _nio ), and find the specific value (X _k , Y _k )
The specified value is stored in the data memory 12 as , and the specific value setting operation is completed.

Next, the operation of inputting figures, characters, etc. using the tablet 1 will be explained based on the flowchart shown in FIG.

When the input pen 6 is pressed on the tablet 1, the control circuit 10 detects the pressing of the input pen 6 in step 401, proceeds to step 402, and switches the detection switches 9A and 9B upon generation of the switching signal (S) in the same way as described above.
is closed and set to the state of detecting the X coordinate of the input pen 6. After performing current-to-voltage conversion in step 403, the control circuit 10 proceeds to step 404 and compares X ₁ +Y ₂ with a specific value (X _K ) stored in the data memory 12. And X ₁ + X ₂
If is larger than the specific value, the process proceeds to step 405, and the above-mentioned calculation is performed using the output voltages X ₁ and X ₂ .
The X coordinate of the input pen 6 is determined and stored in the data memory 12. When the X coordinate is determined, the control circuit 10 proceeds to step 406 and determines whether or not the detection of the Y coordinate has been completed.Since the Y coordinate has not yet been determined, the control circuit 10 returns to step 402 and generates the switching signal (S). Detection switches 9C and 9D are closed. Then, by repeating steps 403 to 405 in the same manner as described above, the Y coordinate is obtained and stored in the data memory 12. Next, proceeding from step 406 to step 407, the calculated position coordinate (X, Y) data of the input pen 6 is read from the data memory 12,
By writing data to a predetermined position in the image memory 13 based on the read data, the position of the input pen 6 is displayed on the display device 14. After displaying, the control circuit 10 returns to step 401 and detects the next coordinate position of the input pen 6. Therefore, when the input pen 6 is moved over the tablet 1,
Since the position coordinates are detected one after another and displayed on the display device 14 as described above, the movement locus of the input pen 6 is displayed. This allows input of figures, characters, etc.

In this case, since X ₁ + Y ₂ and Y ₁ + Y ₂ are greater than the specific values, the position coordinates of the input pen 6 can be accurately determined.
No deviation occurs between the position of the input pen 6 and the display position on the display device 14. Furthermore, since the specific value is set to a value that matches the characteristics of the tablet 1 as described above, display deviation can be almost prevented.

However, when the input pen 6 is lightly pressed against the tablet 1, the amount of current flowing out from the tablet 1 decreases due to an increase in the contact resistance of the contact part, and the calculated position coordinates of the input pen 6 (X ,
Y) becomes a value that deviates from the actual position coordinates, and the display position on the display device 14 also deviates. Therefore, when the control circuit 10 detects in step 404 that the current flowing out from the tablet 1 is small and that X ₁ +Y ₂ or Y ₁ +Y ₂ is smaller than a specific value, the control circuit 10 returns from step 404 to step 401 to change the input pen at that time. Detection of position coordinates No. 6 is ignored. This prevents the screen from being displayed at a position shifted from the position of the input pen 6. Note that the position coordinates of the input pen 6 are detected every several tens of milliseconds.
Even if the detection of one point is ignored, the display of the movement trajectory of the input pen 6 is not significantly affected.

When inputting figures, characters, etc. is completed by moving the input pen 6 on the tablet 1 in this way, the data stored in the data memory 12 is processed by signal processing by operating the switch shown in the figure on the tablet 1. By sending the data to the transmission line 16 via the circuit 15, it is possible to display figures, characters, etc. input with the input pen 6 on the display device of another device. On the other hand, data transmitted from another device can be displayed on the display device 14 by processing it in the signal processing circuit 15, and image communication can be performed between the devices.

(G) Effects of the Invention As described above, the coordinate data input device of the present invention detects and displays the position coordinates of the input pen based on the current flowing through the constant current type tablet, when the input pen is lightly pressed against the tablet. In this case, by configuring the input pen to ignore position coordinate detection and setting the current value when the detection is ignored according to the characteristics of the tablet by measuring multiple points on the tablet. Prevents the display position from shifting,
It eliminates breaks in the drawing line caused by the movement of the input pen, allowing for smooth drawing, and is ideal for coordinate data input devices that use a transparent tablet placed on a display device such as a liquid crystal display. It is something.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the coordinate data input device of the present invention, FIG. 2 is a sectional view showing the configuration of the main part of FIG. 1, and FIGS. 3 and 4 show the operating state of FIG. 1. Flowchart, FIG. 5 is a diagram showing the display state of the display device of FIG. 1. 1... Tablet, 6... Input pen, 7... Constant current source, 8A to 8D... Current-voltage conversion circuit, 1
0...Control circuit, 12...Data memory, 13...
...image memory, 14...display device.

Claims (1)

[Claims] 1. An input pen connected to a constant current source, a constant current tablet, a circuit that converts the current flowing into the tablet from the input pen into a voltage according to the position of the input pen, and a converter. a calculation means for calculating the position coordinates of the input pen by performing a predetermined calculation process based on the voltage applied to the input pen; means for determining data for detecting whether the current is constant, means for detecting whether or not the current is constant based on the data of the means, and displaying the input pen position determined by the calculating means on a display device; A coordinate data input device comprising a control means for prohibiting display when it is detected that no current is present.