JPH06309088A - Position detector - Google Patents

Abstract

(57) [Summary] [Structure] The level detection unit 3 detects the level from the detection signal detected by the position indicator 101 such as a pen, and the calculation formula selection unit 5 is responsive to the signal from the level detection unit 3.
Select the calculation method with. The position coordinate calculation unit 4 calculates and outputs the position coordinates from the detection signal according to the calculation method selected by the calculation formula selection unit 5. In addition, the amplification factor of the detection signal is changed according to the signal from the level detection unit 3 so that the detection signal is amplified to a level that improves the S / N ratio. [Effect] For changes in the waveform of the detection signal due to height,
The effect of stabilizing the position coordinate detection accuracy by changing the calculation method and the S / N by changing the amplification factor
Since the ratio can be improved and the error due to digit cancellation occurring in calculation can be reduced, the position coordinate detection accuracy can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting method for a position detecting device which detects a position by a position indicator such as a pen.

[0002]

2. Description of the Related Art A conventional coordinate detecting device is disclosed in Japanese Patent Laid-Open No.
There is an electromagnetic induction type tablet represented by Japanese Patent No. 16240. This type of position detection plate is formed by arranging loop coils in parallel on a substrate typified by a glass epoxy resin substrate. A voltage is applied to the parallel loop coil group of this detection plate, the electromagnetic wave generated by the applied voltage is detected by a position indicator such as a pen, this is converted into a voltage, and this energy is once again converted into an electromagnetic wave on the position detection plate. reflect. The reflected electromagnetic wave is received by the loop coil of the position detection plate and converted into a voltage. The voltage signal due to the reflected electromagnetic wave is amplified with a fixed amplification factor, and the position calculation unit calculates and outputs the position coordinates by a single calculation method.

Further, there is a capacitance type tablet typified by JP-B-55-22818. In this method, voltages are sequentially applied to conductor electrodes arranged in parallel on a position detection plate in a predetermined order, and the applied voltage is detected by a position indicator such as a pen. The detected voltage group is amplified by a predetermined amplification factor, and the position calculation unit calculates and outputs the position coordinates by a single calculation method.

[0004]

However, the above-mentioned prior art cannot cope with the change in the spread of the detected voltage group that occurs when the pen moves in the height direction. As can be seen from the conventional waveform of FIG. 6, when the position indicator is close to the position detection plate (height h), the detected voltage group shows a steep distribution and the position indicator moves away from the position detection plate (see FIG. 6). Height 2h)
And the distribution becomes smooth. When the calculation method is usually determined based on the height h, it ideally does not match the data of the height 2h. In particular, since the shape of the waveform differs depending on the height, the conventional single calculation method has a problem that the position calculated from the detected voltage changes depending on the height, which lowers the position coordinate detection accuracy.

Further, since the level of the detection voltage group becomes smaller as the distance from the height increases, the signal / noise (S
/ N) ratio decreases, the position coordinate detection accuracy decreases, and because the signal itself becomes smaller and the number to be calculated becomes smaller, the calculation error becomes relatively large due to the problem of the number of calculation digits. There is a problem that the position coordinate detection accuracy decreases.

Therefore, the present invention solves the above-mentioned problems by maintaining the position coordinate detection accuracy even in the height direction, and
It is an object of the present invention to improve the position coordinate detection accuracy by improving the / N ratio and reduce the calculation error to improve the position coordinate detection accuracy.

[0007]

The position detecting device of the present invention comprises: (1) Position detection in which a voltage is applied to a plurality of conductors arranged in parallel on a position detection plate and the applied voltage is detected by a position indicator. In the device, a voltage level detecting unit that has a position detecting unit that detects a position from a detected voltage group, and the position detecting unit outputs a voltage level signal according to the voltage from the detected voltage group, and from the voltage level detecting unit A position calculation method selection unit that selects one position calculation method from a plurality of position calculation methods according to the voltage level signal, and a position calculation method that is selected by the position calculation method selection unit from the detected voltage group. It is characterized by comprising a position calculation unit.

(2) In a position detecting device which outputs a voltage or an electromagnetic wave from a position indicator and detects the voltage or the electromagnetic wave by a position detecting plate in which a plurality of conductors are arranged in parallel, the position is detected from the detected voltage group. A position detecting section for detecting a voltage level, and the position detecting section outputs a voltage level signal corresponding to the voltage from the detected voltage group, and a plurality of position calculating methods based on the voltage level signal from the voltage level detecting section. A position calculation method selection unit that selects one position calculation method from among the above, and a position calculation unit that calculates the position from the detected voltage group by the position calculation method selected by the position calculation method selection unit. And

(3) The means (1) or the means (2)
It is characterized in that the described voltage level detection unit is configured by an electric circuit.

(4) The means (1) or the means (2)
It is characterized in that the position calculation unit described is constituted by an electric circuit.

(5) The means (1) or the means (2)
The position detection device described above is characterized by including the voltage level detection unit described in the means (3) and the position calculation unit described in the means (4).

(6) In a position detection device in which a voltage is applied to a plurality of conductors arranged in parallel on a position detection plate and the applied voltage is detected by a position indicator, a detected voltage group is detected according to the detected voltage. A voltage level detection unit that outputs a voltage level signal, an amplification factor switching unit that switches the amplification factor of the detection voltage according to the voltage level signal, a detection voltage amplification unit that amplifies the detection voltage with the amplification factor switched by the amplification factor switching unit, It is characterized in that it has a position calculation unit for calculating a position by the detection voltage amplified by the detection voltage amplification unit.

(7) In a position detecting device which outputs a voltage or an electromagnetic wave from a position indicator and detects the voltage or the electromagnetic wave by a position detection plate in which a plurality of conductors are arranged in parallel, a detected voltage from a detected voltage group. Voltage level detection section for outputting a voltage level signal according to the voltage level signal, an amplification rate switching section for switching the amplification rate of the detection voltage according to the voltage level signal, and a detection voltage for amplifying the detection voltage with the amplification rate switched by the amplification rate switching section. It is characterized in that it has an amplification section and a position calculation section for calculating a position based on the detection voltage amplified by the detection voltage amplification section.

(8) The means (1) or the means (2)
The position detection device described above is characterized by including the amplification factor switching unit and the detection voltage amplification unit described in the means (6).

[0015]

【Example】

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention. The electrode switch 2 by the panel control circuit 104
Is controlled to select one of the electrodes 1 on the position detection plate 100 and apply a voltage of 5V. The voltage is sequentially selected one by one from left to right in FIG. 1 in order and 5 V is applied. The applied voltage is detected by the position indicator 101, and the voltage detection unit 102 performs processing such as amplification and filtering. This detection voltage is generated at time intervals according to the voltage applied to each electrode 1, and its level corresponds to the position of the pen. The detection voltage of the highest level is generated at a position corresponding to the electrode closest to the pen, and becomes smaller as the signal from the electrode farther from the pen becomes a signal. Also,
The maximum detection level also depends on the height of the pen, and the higher the height, the smaller the level. The conventional waveform of FIG. 6 shows such a situation, but it can be seen that the detected voltage at the height 2h is smaller than that at the height h.

From the detected voltage group detected by the voltage detecting section 102, the level detecting section 3 sends a level signal corresponding to the maximum voltage level to the position coordinate calculating section 4. In this embodiment, the position coordinate calculation unit 4 has both a position calculation method selection unit and a position calculation unit. The position coordinate calculation unit 4 is the voltage detection unit 1.
The position coordinates are calculated by applying the calculation method selected by the level signal from the level detection unit 3 to the detected voltage group from 02.

The actual detected voltage group from the voltage detector 2 is output as a dotted line instead of the solid line in FIG. Here, the term "detection voltage group" is described because the detection voltage corresponding to the number of the electrodes 1 is generated by sampling the detection voltage corresponding to the voltage applied to each electrode 1. FIG. 2 shows a waveform when the detected voltage group is actually detected by the circuit in a state where they are lined up in time. The solid line in FIG. 2 is a waveform ideally obtained when the electrodes are dense and the interval is narrow. Since the position coordinates correspond to the peaks of the solid line waveform in FIG. 2, the position coordinates are calculated by approximately calculating the solid line waveform in FIG. 2 from the detected voltage group.

FIG. 3 is a flow chart of a concrete process of the position coordinate calculation section 4. The detected voltage group from the voltage detection unit 102 is detected by the voltage detection processing 21, the level signal from the level detection unit 3 is fetched by the level detection processing 22, and the fetched level and the arbitrarily determined threth level are calculated and selected. The comparison is made in processing 23. The calculation selection process 23 selects calculation X24 and calculation Y25 based on this threth, and the position coordinate is calculated based on the detected voltage group from the voltage detection process 21 by the selected calculation process. Then, the position coordinate output processing 26 outputs the position coordinates.

Here, two or more calculation methods are prepared and selected, as shown in FIG. 6, when the height is h and when the height is 2.
This is because the distribution of the detected voltage is different at the time of h, and these two curves cannot be approximated by one approximate expression. When approximation is performed with one approximation formula, the error due to approximation naturally increases. Therefore, the approximation can be improved by using two or more calculation methods. Since the position coordinates correspond to the vertices of this curve, the better the approximation, the better the position coordinate detection accuracy will be.

(Embodiment 2) FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention.

In the first embodiment, the calculation method is selected by the position coordinate calculation unit 4, but in the present embodiment, the position coordinate calculation unit 4 is selected.
And the calculation method selection unit 5 for selecting the calculation method. This embodiment will be described as a configuration diagram showing a case where the calculation is realized by hardware, but it is not necessary that all are hardware. The calculation method selection unit 5 is configured to generate a calculation method selection signal for selecting one operation circuit from the operation circuits of the position coordinate calculation unit 4 according to the level signal from the level detection unit 3. The arithmetic circuit is selected by the calculation method selection signal, and the arithmetic circuit calculates the position coordinate from the detected voltage group from the voltage detecting unit 102 and outputs the position coordinate. In the above embodiment, the position detection unit 10
It is also possible to perform all 3 by software processing.

(Embodiment 3) FIG. 5 is a schematic configuration diagram showing a third embodiment of the present invention. The operation up to the voltage detection unit 102 is the same as in the case of FIG. 1 of the first embodiment. Voltage detector 10
The level of the detected voltage group detected in 2 is detected by the level detecting section 3, and the amplification factor X of the amplifier circuit 6 is detected by this level signal.
7 or the amplification factor Y8 or the amplification factor Z9 is selected, the detected voltage group is amplified by the selected amplification factor, and the position coordinate calculation unit 4 calculates the position coordinate based on the amplified detected voltage group. Calculate and output.

FIG. 6 is a diagram showing how the waveform changes according to this embodiment. In the conventional single amplification factor, the difference between the detected voltage levels was large between the height h and the height 2h.
However, as described above, according to this embodiment, the height h and the height 2
The difference in the detection level at the time of h can be almost eliminated. Although the noise component is also amplified by this amplification, the S / N ratio can be relatively improved by using the difference in the calculation, and the error due to the digit cancellation that occurs in the calculation is reduced, and the position coordinate is substantially The detection accuracy is improved.

(Embodiment 4) As a fourth embodiment of the present invention, FIG. 7 is an embodiment in which the amplification factor switching means is included in the position coordinate calculator 4 in the configuration of FIG. It is divided into three amplification factors according to the level signal from the level detector 3.
Here, k corresponds to the amplification factor. Arbitrarily determined thl
eth1 and threth2 are compared with the level signal, respectively, and the level comparison is performed according to the magnitude relationship.
1> level and threth ≦ level ≦ thlet2 and threth2 <level. Depending on this state, one of the amplification factor determination processes 24, 25, and 26 is selected to determine the amplification factor k. The detected voltage group is amplified by the amplification processing 27 according to the determined amplification factor k. The position coordinates are calculated in the position calculation process 28 using the amplified detected voltage group and are output from the position coordinate output process 26. Further, the same effect can be obtained even when an automatic gain control circuit is used as the amplification factor switching means.

(Embodiment 5) FIG. 8 shows an embodiment in which the calculation method selection unit and the amplification factor switching unit of the present invention are combined. The configuration is the same as that of FIG. 1, and the processing of the position coordinate calculation unit 4 is an embodiment in which the processing means shown in FIG. 7 is used. The content of the processing is a combination of the embodiments of FIGS. 3 and 7, and the amplification factor conversion of FIG. 7 is first performed, and then the calculation method selection of FIG. 3 is performed.

As can be seen from FIG. 6, the level is amplified by amplification by the amplification means of the present invention, but at the same time, the noise component is also amplified. However, since the difference is used in calculation, the S / N ratio is relatively improved, and the position coordinate detection accuracy is improved. Furthermore, since the approximation accuracy can be increased by selecting the calculation method, the position coordinate detection accuracy can be synergistically improved.

[0027]

With the above-described structure, the problem of deterioration of the position detection accuracy due to the difference in height can be solved because the approximation to the ideal curve can be improved by selecting the calculation method.

Further, since the level of the detection voltage group becomes smaller and the S / N ratio becomes worse by moving away in the height direction, the position detection accuracy is deteriorated, and the position detection accuracy is deteriorated due to the digit cancellation caused by calculation. The problem to be solved is to change the amplification factor by the level signal from the level detection unit to increase the detection signal of a small level, so that the level difference due to the height can be reduced and the S / N ratio can be reduced. It is possible to improve the position detection accuracy, and the digit loss caused by calculation is reduced by increasing the detection voltage level, and the position detection accuracy is substantially improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram in a first embodiment of the present invention.

FIG. 2 is a diagram showing a detected voltage detected by the position indicator according to the first embodiment of the present invention.

FIG. 3 is a flowchart of a specific process of the position coordinate calculation unit 4 in the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram in the second embodiment of the present invention.

FIG. 5 is a schematic process drawing in the third embodiment of the present invention.

FIG. 6 is a diagram showing waveforms in the first, third, and fifth embodiments of the present invention.

FIG. 7 is a flow chart of processing of a position coordinate calculation unit 4 in the fourth embodiment of the present invention.

FIG. 8 is a flow chart of processing of the position coordinate calculation unit 4 in the fifth embodiment of the present invention.

[Explanation of symbols]

 1 electrode 2 electrode switch 3 level detection unit 4 position coordinate calculation unit 5 calculation method selection unit 6 amplification circuit 100 position detection plate 101 position indicator 102 voltage detection unit 103 position detection unit 104 panel control circuit

Claims (8)

[Claims] 1. A position detection device for applying a voltage to a plurality of conductors arranged in parallel on a position detection plate and detecting the applied voltage with a position indicator, the position detection detecting a position from a detected voltage group. A position level detecting section that outputs a voltage level signal corresponding to a voltage from the detected voltage group, and one of a plurality of position calculating methods based on the voltage level signal from the voltage level detecting section. A position detecting device comprising a position calculating method selecting unit for selecting a position calculating method, and a position calculating unit for calculating a position from the detected voltage group by the position calculating method selected by the position calculating method selecting unit. . 2. A position detecting device that outputs a voltage or an electromagnetic wave from a position indicator and detects the voltage or the electromagnetic wave by a position detecting plate in which a plurality of conductors are arranged in parallel, and detects the position from the detected voltage group. A voltage level detecting section having a position detecting section for detecting, wherein the position detecting section outputs a voltage level signal corresponding to a voltage from a detected voltage group, and a plurality of position calculating methods based on the voltage level signal from the voltage level detecting section. A position calculation method selection unit that selects one position calculation method from among the above, and a position calculation unit that calculates a position from the detected voltage group by the position calculation method selected by the position calculation method selection unit. Position detection device. 3. The position detecting device according to claim 1, wherein the voltage level detecting unit is configured by an electric circuit. 4. The position detecting device according to claim 1, wherein the position calculating unit is configured by an electric circuit. 5. The voltage level detection unit according to claim 3,
The position detecting device according to claim 1 or 2, further comprising the position calculating unit according to claim 4. 6. A position detecting device in which a voltage is applied to a plurality of conductors arranged in parallel on a position detecting plate and the applied voltage is detected by a position indicator, wherein a voltage is detected from a detected voltage group according to the detected voltage. A voltage level detection unit that outputs a level signal; an amplification factor switching unit that switches the amplification factor of the detection voltage according to the voltage level signal; a detection voltage amplification unit that amplifies the detection voltage with the amplification factor switched by the amplification factor switching unit; A position detection device comprising a position calculation unit that calculates a position based on the detection voltage amplified by the detection voltage amplification unit. 7. A position detecting device which outputs a voltage or an electromagnetic wave from a position indicator and detects the voltage or the electromagnetic wave by a position detecting plate in which a plurality of conductors are arranged in parallel is used. A voltage level detection unit that outputs a voltage level signal in response to the voltage level signal; an amplification factor switching unit that switches the amplification factor of the detection voltage according to the voltage level signal; and a detection voltage amplification that amplifies the detection voltage with the amplification factor switched by the amplification factor switching unit. And a position calculation unit that calculates a position based on the detection voltage amplified by the detection voltage amplification unit. 8. The position detection device according to claim 1 or the position detection device according to claim 2, wherein the position detection device comprises the amplification factor switching unit and the detection voltage amplification unit according to claim 6. apparatus.