JPS61120230A - Position input device - Google Patents

Abstract

PURPOSE:To detect an input position with simple circuit constitution and high accuracy by providing previously a correction table corresponding to a detection error of the input position proper to an input position detector and supplying a detecting position signal to said table to obtain a position correcting signal. CONSTITUTION:An input position correcting circuit consists of an input position detector 26, an amplifier 27, a sample holding circuit 28, etc. together with an X/Y coordinate correction table 30. The position correction data corresponding to a detection error is stored previously to the table 30 in response to the characteristics of the detector 26. The detected X/Y coordinate position are corrected with difference to the correction data and delivered as position signals in the digital value. Thus a detection error of the input position even is detected with the detector 26 due to an uneven resistance factor of a resistor can be corrected through the table 30. This attains the detection of an input position with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the field to which the invention pertains The present invention relates to a position input device, particularly a position input device having an input position detection device, which corrects a detection error of an input position in the input position detection device. The present invention relates to a position input device having a position input device.

(2) Description of the Prior Art Conventionally, as an input position detection device, there is one that uses a pressure sensitive resistor sheet to input information by utilizing a change in resistance at a pressed position. FIG. 5 is a circuit diagram showing an example of its configuration. I died in the same picture.

A conductive layer 2 of a metal sheet is disposed on the upper surface of the pressure sensitive sheet 1, and a resistor 3 having a uniform sheet resistance is laminated on the lower surface, and an input surface is constituted by these. Figure 6 shows its laminated structure, and A-A in Figure 5.
FIG.

Between the conductive layer 2 on the input surface and the ground terminal.

A power supply 4 for applying driving voltage is connected, and this power supply 4
Therefore, a positive driving voltage is always applied to the conductive layer 2. On the other hand, on each side of the resistor 3.

Detection electrodes 5a and 5b each having a plurality of diodes arranged and connected at equal intervals are provided. Each detection electrode 5a,
5b and the ground terminal are provided with constant current sources 22a and 22, respectively.
b is connected to the reed, and each detection electrode 5a, 5 is connected by these.
The currents flowing out from b are each made constant independently. The constant current source 22a connects the source and gate of the field effect transistor 50 through a resistor Rs, and outputs a constant current 11 when a positive voltage -tI is applied to the drain by input. 22b also has a similar configuration. Further, operational amplifiers 21a and zxb are connected between the detection electrode 5a and the terminal 101, and between the detection electrode 5b and the terminal 101, respectively.

Potential differences between the detection electrode 5a and the terminal 101 and between the detection electrode 5b and the terminal 101 are detected, and these potential differences are output as position coordinates (X, Y) of the input (pressed) point. moreover,
The comparison circuit 24 compares the potential appearing on the detection electrode 5a with the output voltage Fi1 of the reference power supply 25, and when the potential is higher than this reference voltage, the comparison circuit 24 generates two signals of "H" level. 2. When the signal strength is H'' level, it is determined that there is an input (press), and the X and Y signals obtained at that time are considered significant.

FIG. 7 is an equivalent circuit for explaining the operation of the device shown in FIG. When input is performed, the conductive layer in the input device comes into electrical contact with the resistor 3 via the pressure-sensitive sheet 1 due to the pen pressure. In FIG. 7, when a power source E for applying a driving voltage is applied to the input position indicated by the reference numeral 100, the equivalent resistance R between the detection electrode 5a and the input position 100,
Similarly, the constant current worker 1 connects the detection electrode 5b and the input position 100.
A constant current flows through the equivalent resistance R between. Resistor 3
has a uniform resistance value, R1 is proportional to the distance between the detection electrode 5a and the input position 100, and R2 is proportional to the distance between the detection electrode 5b and the input position 100. The value of R1 and island is the voltage drop R due to constant current It, Is between both resistors.
IIt is obtained by K by measuring R,I. Therefore, by measuring Rt L and R1It, the X and Y coordinates of the input position 100 can be obtained.

R3 is the equivalent resistance between the input position 100 and the terminal 101 of the resistor 3. Detects the potential difference between If the subtraction circuit is constructed from elements with high input impedance, such as operational amplifiers, the influence of Rj can be ignored. In addition, the detection electrode 5
Since the current flowing through the diode in a is also constant, the voltage drop in the diode in a can be known in advance and corrected. Similarly,
A subtraction circuit including an operational amplifier 21b detects the potential difference between the input position 100 and the output terminal 103 of the detection electrode 5b via the resistor R1.

However, the coordinate detection accuracy of this device is determined by the uniformity of the sheet resistance of the resistor 3, and if the sheet resistance is not uniform, the relationship between the equivalent resistances Rt and R1 in Fig. 7 and the input position will not be linear. , there was a drawback that the input coordinates were distorted.

(3) Purpose of the Invention The present invention has been made in order to eliminate these drawbacks. A correction table corresponding to the input position detection error peculiar to the input position detection device is prepared in advance, and the The present invention is characterized in that a position signal obtained from an input position detection device is input, and a position correction signal obtained by correcting the input position is obtained.

The drawings will be described in detail below. (4) Explanation of the structure and operation of the invention FIG. This corresponds to the one shown in Figure 1.

27X, 27Y are amplifiers, 28X, 28)' are sample and hold circuits, 29x, 29y are AD conversion circuits, 30x
30y is a y-coordinate correction table, and 30y is a y-coordinate correction table. To operate this, the
After amplifying to a constant level with x and 27Y, sample and hold circuits 26x and 28M sample and hold at predetermined intervals, and 9AD conversion circuits 29X and 29Y convert the analog X-coordinate position signal and y-coordinate position signal into digital values. Convert. And an X coordinate correction table 30x prepared in advance according to the characteristics of the input position detection device 26.

In the y-coordinate correction table 30y,
The device inputs a coordinate position signal and an X-coordinate position signal, respectively, and outputs an X-coordinate position signal and an X-coordinate position signal, which are obtained by correcting the input position corresponding to the X-coordinate position signal and X-coordinate position signal, respectively.

FIG. 2 shows the relationship between the X coordinate position signal and the correction table. In the figure, reference numeral 31 indicates an example of the relationship between the X-coordinate input position to the input position detection device 26 and the X-coordinate position signal from the input position detection device 26). Since the resistivity is non-uniform, the line 9 does not form a straight line, and a deviation from the straight line 32 showing an ideal relationship between the two results in an X-coordinate detection error. 33 indicates the data written in the X-coordinate correction table 30xK for the X-coordinate position signal, and refer to the corresponding correction data in the correction table 30X with the X-coordinate position signal. Output as a value.

The present invention has such a configuration.

Even if the input position detection device has an input position detection error due to nonuniform resistivity of the resistor, it is possible to accurately detect the input position by correcting it using the correction table, and the resistivity of the resistor is not uniform. It can also be used uniformly. Therefore, the yield of resistors is improved and there is an economical effect. For convenience of explanation.

Although the X coordinate has been described, the y coordinate can also be corrected in the same way. In addition, in the block diagram of the input position correction circuit shown in FIG.
, AD conversion circuits 29x, 29M are used for two sets, but it can also be realized using one set by switching and using the X-axis and y-axis in a time division manner. xs mark correction table 3
0x, y411 correction; As an example of how to implement the correction table 30y, a ROM (read-only memory) can be used.

The digital value of the X-coordinate or y-coordinate position signal may be input to the address of the ROM, and the data at that time may be used as the corrected X-coordinate position signal.

In addition, correction data may be created for all input points of the input position detection device 26, or since the resistivity of the resistor 3 changes gradually, the correction data may be
Several representative input points are selected and their position signals are used to complement the correction data for all input points.

FIG. 3 shows another embodiment of the present invention, in which 28 is a sample and hold circuit, and 29 is an AD conversion circuit.

SvJ is a switch, 34x is a data latch circuit for the X coordinate position signal, 34y is a data latch circuit for the X coordinate position signal,
35x is an X coordinate correction table, and 35y is a y coordinate correction table.

After amplifying the X coordinate position signal and the Switch. The sample and hold circuit 28 performs sampling and holding in synchronization with the switching timing of the switch SW, and the AD conversion circuit 29 converts the analog X-coordinate position signal and the X-coordinate position signal into digital values in a time-division manner. , when it is an X-coordinate position signal, the latch circuit 34X latches the X-coordinate position signal, and when it is an X-coordinate position signal, the latch circuit 34Y latches the y-coordinate position signal, and then the digital signal Xi The correction table 35 is simultaneously accessed using the target position signal and the X-coordinate position signal to obtain the corrected X-coordinate position signal and y-coordinate position signal.

FIG. 4 shows an example of the relationship between the input position to the input position detection device 26 and the coordinate position signal.

36 is an input position, and 37 is a position signal. If the resistivity in the X-coordinate direction and the resistivity in the y-coordinate direction of the resistor of the input position detection device 26 are not independent, the X-coordinate, y-coordinate It is necessary to correct the coordinate detection error. When the position signal 37 in FIG. 4 is input to the correction table 35 shown in FIG. 3, data indicating the input position 36 is input.

Since the present invention has such a configuration, even if the input position detection device has an input position detection error due to non-uniform resistivity of the resistor over the entire surface.

The input position can be detected with high accuracy by correcting the entire surface using the correction table. (5) Description of effects As explained above, the present invention can cope with the input position detection error inherent in the input position detection device. An input position correction table is prepared in advance, and the X coordinate position signal and the Once entered into the coordinate correction table.

The rounding 2 circuit configuration that outputs digital data corrected for errors in the input position is simple and can detect the input position with high accuracy. Furthermore, since it can be used even when the resistivity of the resistor of the input position detection device is non-uniform, the yield of the resistor is improved and there is an economical effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an input position correction circuit according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of an embodiment of a correction table, FIG. 3 is another embodiment of the present invention, and FIG. 4 is an input position correction circuit. FIG. 5 is an explanatory diagram illustrating the relationship between a position and a coordinate position signal, and FIG. 5 is a circuit diagram of a conventional input position detection device. FIG. 6 is an explanatory diagram for explaining the structure of the input position detection device, and FIG. 7 is an explanatory diagram for explaining the operation of the device shown in FIG. 1 is a pressure sensitive sheet, 2 is a conductive layer, 3 is a resistor, 4 is a power source,
5a, 5b are detection electrodes, 21a, 21b are amplifiers, 22
a, 22b are constant current sources, 24 is a comparison circuit, 25 is a reference power source, and 26 is an input position detection device. 27x and 27y are amplifiers, 28 and 287 are sample and hold circuits, and 29 and 297 are AD conversion circuits. 30X is an X coordinate correction table, 30y is a y coordinate correction table, 31 is an X coordinate signal, and 32 is an ideal signal. 33 is correction data, 34 and 347 are latch circuits. 35x represents an X coordinate correction table, 35y represents a Y coordinate correction table, 36 represents an input signal, and 37 represents a position signal.

Claims (1)

[Claims] In a position input device having an input position detection device that outputs a position signal corresponding to the coordinates of an input point position, AD conversion converts at least an analog value position signal obtained from the input position detection device into a digital value position signal. circuit and
A correction table that inputs the digital value position signal and outputs a digital value position correction signal is provided, and the input position detection error of the input position detection device and data to be corrected are stored in the correction table in advance, and the input position The analog value position signal obtained from the detection device is converted into a digital value position signal by the AD conversion circuit, and the digital value position signal is inputted into a correction table to generate a digital value position correction signal corresponding to the digital value position signal. A position input device characterized in that: