JPH0439696B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] Before detecting the coordinates on the resistor input surface using the capacitive coupling method, the calibration value is measured two or more times, and when the two or more consecutive calibration values match. A coordinate value calibration method that uses the calibration values to calibrate the coordinate values.

[Industrial application field]

The present invention relates to a coordinate calibration value correction method for correcting calibration values for calibrating measurement coordinates on an input surface of a resistor.

BACKGROUND ART A method of measuring coordinates on a resistor input surface using an electrostatic coupling method is widely used in the field of information processing. The capacitively coupled coordinate detection device used to carry out this method has the following advantages: it is easy to make the resistor input surface transparent, and it is possible to drive an input surface of any size with the same control circuit. be.
An example of this coordinate detection device is shown in FIG.

In Fig. 2, 1 is a resistor input surface, 2 to 5 are electrodes, 6 and 7 are AC power supplies, 8 is an amplifier, 9 is a filter, 10 is a phase comparator, 11 is a pen, and 12 is a pen 11 and a resistor. is the capacitive coupling capacitance between the input surfaces 1.

An AC voltage with a phase difference of 90° is applied between electrodes 2 and 3, and an AC voltage with a phase difference of 90° is applied between electrodes 4 and 5. When point 13 is pointed to, the voltage of the phase corresponding to that point is transferred to amplifier 8 via capacitance
The signal is input to the phase comparator 10 after unnecessary components are removed by the filter 9. Phase comparator 1
0 compares the phase of this input voltage with the voltage of power supply 6,
The resulting output is converted to coordinates.

However, the above-described electrostatic coupling capacitance 12 has the disadvantage that the obtained coordinate position is not accurate because it is easily influenced by the temperature and humidity of the surrounding environment.

[Conventional technology]

Conventionally, in order to improve the accuracy of the measured coordinate position values (coordinate values), the calibration values of the resistor input surface were measured in advance only once. The second method is
As shown in Figures 1 and 5, voltages sinωτ of the same phase are applied to the opposing electrodes 2 and 3, 4 and 5, respectively, and the phase at any point on the resistor input surface 1 is adjusted to the calibration value. A, and then each time a coordinate value P is detected, the calibration value A is subtracted from P to obtain an accurate coordinate value.

[Problem that the invention seeks to solve]

By introducing the calibration values using the conventional method described above, the coordinate accuracy was significantly improved.

However, when the pen 11 is strongly hit on the resistor input surface 1, noise is generated in the output of the pen, and although it is rare, the noise may pass through the filter 9 and the calibration value may become incorrect. An example of the waveform of the noise obtained at the output of the amplifier 8 is shown in FIG.

The waveform and timing of the noise vary depending on how the pen 11 is struck against the input surface 1, and cannot be completely removed by the filter 9.

It may be possible to delay the measurement of the calibration value in order to remove the influence of noise, but if you do this, the pen 11
It takes a long time from when the calibration value is positioned on the input surface 1 to when the calibration value is output, which is inconvenient for the user.

[Means for solving problems]

FIG. 1 is a flowchart illustrating the principle of the present invention. In FIG. 1, before the coordinates on the resistor input surface are detected by the capacitive coupling method, the calibration values of the coordinates on the resistor input surface are measured two or more times in steps 101 and 102, and the calibration values are measured once in step 103. The first calibration value A and the second and subsequent calibration values B are compared to see if they match, and if they match, the coordinate values are calibrated using the calibration value, and if they do not match, step 104, 102, 103 Measure the calibration values until two or more consecutive calibration values match. The matched calibration value is set as a corrected calibration value, and the coordinate values are calibrated using this corrected calibration value.

[Effect]

Accurate coordinate values can be obtained by measuring the calibration values two or more times and, when the measured calibration values match, determining the matched values as the correct calibration values.

〔Example〕

FIG. 3 shows an embodiment of the present invention, in which step 1
01 to 104 are equivalent to those shown in FIG. Two consecutive calibration values A in step 103
If and B match, the coordinate value P is detected in step 105, and the calibration value A is subtracted from the coordinate value P in step 106, thereby obtaining a coordinate output.

FIG. 4 is a block diagram showing a coordinate calibration apparatus for implementing an embodiment of the present invention. In the figure, 40 is a measuring section, 41 and 42 are registers, and 4
3 is a comparator, 44 is an AND gate, and 45 is an inverter gate.

The first calibration value measured by the measurement unit 40 is stored in the register 41. When the second calibration value is measured by the measurement unit 40, the contents of the register 41 are shifted to the register 42, and the second measurement value by the measurement unit 40 is stored in the register 41. Comparator 43 compares the contents of registers 41 and 42, and when they match, compares the contents of register 41,
When they match, the contents of register 41 are passed through AND gate 44 and output as correct calibration values; when they do not match, the contents of register 41 are shifted to register 42, and the same operation is repeated.

According to experiments, the coordinate values determined from the calibration values when the same calibration values were obtained twice in a row were accurate.

In the above example, the correct calibration value was determined when two consecutive calibration values matched, but in a noisy environment, the calibration value was measured three or more times, and the correct calibration was determined when all calibration values matched. May be used as a value.

Experiments have shown that in any case, coordinate detection is not delayed due to non-convergence of the calibration values.

〔Effect of the invention〕

As explained above, according to the present invention, only when the calibration value matches two or more times in a row is the correct calibration value and the subsequent detection coordinates are calibrated. The accuracy of detecting coordinates on the body input surface is improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the principle of the present invention;
FIG. 2 is a schematic block diagram showing an example of a coordinate detection device applied to the present invention, FIG. 3 is a flowchart showing an embodiment of the present invention, and FIG. 4 is a flowchart showing an embodiment of the present invention. FIG. 5 is a block diagram showing a coordinate calibration device, FIG. 5 is a flowchart showing a conventional calibration method, and FIG. 6 is an example of a noise waveform obtained at the output of an amplifier. DESCRIPTION OF SYMBOLS 1... Resistor input surface, 2-5... Electrode, 6, 7... Power supply, 8... Amplifier, 9... Filter, 10... Phase comparator, 11... Pen.

Claims (1)

[Claims] 1. In a method of measuring the calibration value of the coordinates before detecting the coordinates on the resistor input surface by the capacitive coupling method, the calibration value of the coordinates of the resistor input name is measured N times (N
is an integer greater than or equal to 2), compare whether all of the N calibration values match, and if they match, use that calibration value as the corrected calibration value, and if they do not match, perform N consecutive calibrations. A method for correcting coordinate calibration values, characterized in that the calibration values are measured until the values match, and the matched calibration values are used as corrected calibration values.