JP2000242403A - Pressure sensitive device and method for inputting coordinate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coordinate input device capable of highly accurately measuring an input position even when a pressure is low or touch resistance of a tablet is large. SOLUTION: This device is provided with a pressure sensitive tablet having resistance sheets 1 and 2. Further, the device is provided with a detecting part 4 for detecting the touch resistance of the pressure sensitive tablet, a measuring time determining part 6 for determining measuring time corresponding to the touch resistance detected by the detecting part 4 and a coordinate measuring part 5 for measuring a coordinate at timing corresponding to the measuring time determined by the measuring time determining part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input device using a touch panel, which is used in portable information terminals and the like.

[0002]

2. Description of the Related Art Used in portable information terminals and the like,
An input device using a touch panel (pressure-sensitive tablet) is required to have considerable accuracy for inputting handwritten characters and the like. That is, in order to accurately recognize the input characters and the like, it is necessary to obtain an accurate coordinate position where the input has been made to the tablet.

As a conventional technique for obtaining an accurate input position on a tablet, there is a method described in Japanese Patent Application Laid-Open No. 4-181418. Japanese Patent Application Laid-Open No. 4-181418 discloses that an input position on a tablet is corrected according to pen pressure,
Further, there is disclosed a technique for obtaining a more accurate coordinate position by measuring an input position a plurality of times and taking an average.

[0004]

However, in the above-mentioned prior art, if the tablet is not sufficiently pressed, even if the input position is measured a plurality of times, the accurate coordinate position is obtained. Cannot be detected.

Further, the tablet used for the input device has a characteristic as a capacitor due to its structure, and it takes time to charge or discharge the electric charge through the contact resistance until the electric potential is stabilized. Therefore, at the time when the potential is not stable, the charge or discharge of the charge held by the tablet is not sufficiently performed, and the measurement result of the input position becomes inaccurate. Therefore, in the above-described prior art, even if the average value of the measurement results of a plurality of times is taken, since the incorrect measurement result at the time when the potential is not stable is included, the accuracy of the coordinate position where the input was made is accurate. It was difficult to obtain a good value.

[0006] In view of the above problems, the present invention can be applied to a case where the pressure is low or the contact resistance of the tablet is large.
An object of the present invention is to provide a pressure-sensitive coordinate input device capable of measuring an input position with high accuracy. The invention further provides
An object of the present invention is to improve the system speed by reducing the time required for measuring an input position when the contact resistance of a tablet of a pressure-sensitive coordinate input device is small.

[0007]

According to the present invention, there is provided a pressure-sensitive coordinate input device, comprising: a pressure-sensitive tablet having a resistance sheet; a detection unit for detecting a contact resistance of the pressure-sensitive tablet; A measurement time determination unit that determines a measurement time according to the resistance, and a coordinate measurement unit that performs coordinate measurement at a timing according to the measurement time determined by the measurement time determination unit, thereby achieving the object. Is done.

[0008] The detection unit may detect the contact resistance using a voltage output from the pressure-sensitive tablet.

A pressure-sensitive coordinate input method according to the present invention is a pressure-sensitive coordinate input method for inputting coordinates from a pressure-sensitive tablet having a resistance sheet, wherein a detecting step of detecting a contact resistance of the pressure-sensitive tablet; A measuring time determining step of determining a measuring time according to the contact resistance detected in the step, and a measuring step of performing coordinate measurement at a timing corresponding to the measuring time determined in the measuring time determining step, This achieves the above object.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. Note that the scope of the present invention is not limited only to the following embodiments.

FIG. 1 shows a pressure-sensitive tablet constituted by a resistive film sheet. The pressure-sensitive tablet shown in FIG. 1 includes a resistive film sheet 1 for reading a Y coordinate, a resistive film sheet 2 for reading an X coordinate, and an input pen 10. Input of coordinates to the pressure-sensitive tablet is performed using the input pen 10.
This is performed by pressing the resistive film sheets 1 and 2 by pressing.

FIG. 2 has the pressure-sensitive tablet shown in FIG.
Terminal. As shown in FIG. 2, on the resistive film sheet 1
Terminal Y at the end_HIs provided at the lower end of the resistive film sheet 1.
Terminal Y_LIs provided. Terminal Y_HAnd terminal Y_LIs
Terminal for inputting / outputting voltage from the coating sheet 1.
You. A terminal X is provided at the right end of the resistive film sheet 2._HProvided
A terminal X is provided on the left end of the resistive film sheet 2._LIs provided
You. Terminal X_HAnd terminal X _LIs the voltage from the resistive film sheet 2.
Terminal for input / output.

FIG. 3 shows the configuration of the pressure-sensitive coordinate input device of the present invention. The pressure-sensitive coordinate input device shown in FIG. 3 includes a resistive film sheet 1 for reading a Y coordinate, a resistive film sheet 2 for reading an X coordinate, a driver circuit 3, an A / D converter 4, and a CP.
U (central processing unit) 5, time setting circuit 6, ROM
(Read only memory) 7 and RAM (random access memory) 8. The Y-coordinate reading resistive film sheet 1 and the X-coordinate reading resistive film sheet 2 are each a part of the pressure-sensitive tablet already described with reference to FIGS.

In FIG. 3, the terminals Y _H of the resistive film sheet 1 are shown.
And terminal Y _L and, terminals of the resistor film sheet 2 X _H and the terminal X _L
Are connected to the driver circuit 3 for driving the tablet. Under the control of the driver circuit 3, each terminal is given one of three states of + 5V which is a power supply voltage, 0V which is a ground voltage, and an open state which is an electrically floating state.

The input of the A / D converter 4 is connected to the terminal Y _L and the terminal X _L. A / D converter 4 converts the voltage appearing on any of the terminals Y _L and the terminal X _L to a digital value, and outputs the CPU5 and time setting circuit 6 is controller. A / D converter 4 based on the selection signal from the driver circuit 3 and converts the voltage appearing on terminal Y _L or terminal X _L selectively.

The time setting circuit 6 determines the contact resistance between the tablets from the digital value output from the A / D converter 4, and sets the time until the tablet voltage suitable for detecting the X coordinate and the Y coordinate stabilizes. When the digital value output from the A / D converter 4 is large, that is, when it can be determined that the contact resistance between the tablets is low, the time setting circuit 6
Sets a short time until coordinate detection. When the digital value is small, that is, when it can be determined that the contact resistance is high, the time setting circuit 6 sets a longer time.

As a method of setting the time in the time setting circuit 6, there are a method of calculating a set value by calculating a digital value, a method of calculating a set value from a digital value using a table prepared in advance, and the like.

The CPU 5 is electrically connected to a ROM 7 storing a control program and a RAM 8 for storing data such as detected coordinate information. CPU5
Executes a control program stored in the ROM 7 and reads and writes data from and to the RAM 8 as necessary.

FIG. 4 shows the state of each terminal of the resistive film sheets 1 and 2 at the time of pressing detection and at the time of coordinate detection. FIG. 4 shows the terminal states at the time of pressing detection, X coordinate reading, and Y coordinate reading by the driver circuit 3 of FIG. Hereinafter, a procedure for detecting coordinates when the tablet is pressed will be described with reference to FIG.

First, before detecting each coordinate position, pressure is detected. To detect the pressed, 5V terminal X _H by the driver circuit 3, as shown in FIG. 4, the terminal X _L, Y _H,
The Y _L is open, the voltage appearing on terminal Y _L sends a signal to the A / D converter 4 to convert the A / D converter 4.

The signal voltage sent to the A / D converter 4 is converted into a digital value and output to the time setting circuit 6. In the time setting circuit 6, a time for detection is calculated according to the value from the A / D converter 4, and the calculated time is calculated as C
Output to PU5.

The CPU 5 sends a control signal to the driver circuit 3 to set each terminal in a predetermined state for detecting X-axis coordinates or Y-axis coordinates in order to start coordinate detection.

When the X-axis coordinate is detected first, the driver circuit 3 sets the terminal _XH to 5 V and the terminal _XL to 0, for example.
V, terminal Y _H, and open Y _L, the voltage appearing on terminal Y _L sends a signal to the A / D converter 4 to convert the A / D converter 4.

The CPU 5 has a timer (not shown). The timer provided in the CPU 5 counts only for the time sent from the time setting circuit 6. By reaching the count value, CPU 5 sends a control signal to the A / D converter 4 to convert the voltage appearing on terminal Y _L.
The CPU 5 calculates an X-axis coordinate position from the digital value output from the A / D converter 4.

After detecting the X-axis coordinate position,
After detecting the pressure again in the manner described above,
Is detected. At this time, a voltage is applied for the pressure detection.
Terminal X_HFrom the terminal Y_HTo the A / D converter 4
Therefore, the terminal to be detected is terminal X _LIt may be.

By detecting the voltage, the time setting circuit 6
After the time is set and the set time is counted (elapsed), detection of the Y-axis coordinate position is started (A / D conversion), thereby completing detection of one set of X-axis coordinates and Y-axis coordinates. I do.

Next, the processing of the pressure-sensitive coordinate input method of the present invention will be described with reference to a flowchart. In the following description, it is assumed that the processing is performed by the configuration of the pressure-sensitive coordinate input device shown in FIG. 3, but the method of the present invention can be implemented by a configuration other than the above.

FIG. 5 is a flowchart showing the processing contents of the pressure-sensitive coordinate input method of the present invention.

In step S 1, the tablet driver circuit 3 is controlled by the CPU 5 to detect the pressing of the X axis, and the power supply voltage 5 is applied to the front surface of the resistive film sheet 2.
V is applied to open the resistive film sheet 1.

In step S2, pressing of the X axis is detected. The detection can be achieved by A / D converting the voltage appearing on the resistive film sheet 1.

In step S3, the time until the potentials of the resistive film sheets 1 and 2 stabilize is determined from the A / D converted value and set by the time setting circuit 6. That is, when the pressure on the tablet is low, the contact resistance is large, so that the time until stabilization is set long. When the pressure is high, the contact resistance is small, so that the time until stabilization is set short.

In step S4, the tablet driver circuit 3 is controlled for the X-axis coordinate measurement to prepare for the X-axis coordinate measurement.

In step S5, the process stands by until the time determined in step S3 elapses, and after the time elapses, the coordinate measurement of the X axis is performed in step S6.

The coordinates of the Y axis are detected in steps S7 to S12 in the same manner as the coordinates of the X axis in steps S1 to S6.

In step S7, the tablet driver circuit 3 is controlled by the CPU to detect the pressing of the Y axis, and the power supply voltage of 5 V is applied to the front surface of the resistive film sheet 1.
To open the resistive film sheet 2.

In step S8, the pressing of the Y axis is detected. The detection can be achieved by performing A / D conversion of the voltage appearing on the resistive film sheet 2.

In step S9, the time required for the potential of the resistive film sheet to stabilize is determined from the A / D converted value.

In step S10, the tablet driver circuit 3 is controlled for the Y-axis coordinate measurement to prepare for the Y-axis coordinate measurement.

In step S11, step S9
In step S12, the coordinate measurement of the X axis is performed.

[0040]

According to the present invention, when the contact resistance of the tablet is measured and the contact resistance is large, a sufficient time for coordinate measurement is ensured so that the input coordinates are not changed after the voltage is stabilized. Can be measured. Therefore, even if the pressure is low or the contact resistance increases due to the characteristics of the tablet, the input coordinates can be measured with high accuracy.

Further, according to the present invention, when the contact resistance of the tablet is small and the voltage stabilization is fast, the stabilization waiting time is shortened to shorten the time required for measuring the input coordinates, thereby improving the system speed. Can be achieved.

As described above, according to the present invention, by changing the measuring method according to the level of pressing, it is possible to cope with a wider range of tablet states, and
Since the processing does not take an unnecessarily long time, the overall performance of the system can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pressure-sensitive tablet constituted by a resistive film sheet.

FIG. 2 is a diagram showing terminals included in the pressure-sensitive tablet shown in FIG.

FIG. 3 is a block diagram showing a configuration of a pressure-sensitive coordinate input device of the present invention.

FIG. 4 is a diagram illustrating a state of each terminal of a resistive film sheet when a pressure is detected and a coordinate is detected.

FIG. 5 is a diagram showing a flowchart of processing contents of a pressure-sensitive coordinate input method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Y-coordinate reading resistive sheet 2 X-coordinate reading resistive sheet 3 Driver circuit 4 A / D converter 5 CPU 6 Time setting circuit 7 ROM 8 RAM 10 Input pen

Claims (3)

[Claims] 1. A pressure-sensitive tablet having a resistance sheet, a detection unit for detecting a contact resistance of the pressure-sensitive tablet, and a measurement time determination unit for determining a measurement time according to the contact resistance detected by the detection unit. A pressure-sensitive coordinate input device, comprising: a coordinate measurement unit that performs coordinate measurement at a timing according to the measurement time determined by the measurement time determination unit. 2. The pressure-sensitive coordinate input device according to claim 1, wherein the detection unit detects the contact resistance using a voltage output from the pressure-sensitive tablet. 3. A pressure-sensitive coordinate input method for inputting coordinates from a pressure-sensitive tablet having a resistance sheet, the method comprising: detecting a contact resistance of the pressure-sensitive tablet; A pressure-sensitive coordinate input method, comprising: a measurement time determination step of determining a measurement time in accordance therewith; and a measurement step of performing coordinate measurement at a timing corresponding to the measurement time determined in the measurement time determination step.