JPH0434173B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate detection device using an electromagnetic induction method.

[Conventional technology]

The coordinate detection device detects when a position on the tablet is indicated by a pointing device such as an electromagnetic pen or cursor.
This is a device that detects the coordinate values of that position. Such a coordinate detection device is disclosed in, for example, Japanese Unexamined Patent Publication No. 159191/1983 and is well known. The outline of the coordinate detection device described in the publication will be explained below using figures.

FIG. 4 is a block diagram of a conventional coordinate detection device. In the figure, 1 is an oscillator, 2 is a counter that reduces the frequency of the oscillation pulse of oscillator 1, and 3 is counter 2.
This is a filter that converts the pulses output from the oscillator into sine wave currents of the same frequency and phase. Reference numeral 4 denotes an excitation coil built into an indicating device such as an electromagnetic pen, and is excited by the current supplied from the filter 3.

5 is a tablet. The tablet 5 is wired with conductive wires for the X-axis and the Y-axis. The conducting wire for the X-axis consists of four conducting wires, the first conducting wire is wired in a meandering manner with a pitch of P, and the second conducting wire is wired with a shift of P/4 pitch from the first conducting wire. . Further, the third conductive wire is laid in a meandering manner in the same direction as the first conductive wire at pitch Q, and the fourth conductive wire is laid with a shift of Q/4 pitch from the third conductive wire. 1st
When the total number of pitches in the conducting wire is n, pitches P and pitches Q are in the relationship nP=(n-1)Q. The Y-axis conducting wire is also the same as the X-axis conducting wire except that the wiring direction is different by 90 degrees.
5X and 5Y indicate four conductive wires for the X-axis and four conductive wires for the Y-axis, respectively.

6 is a command signal from a data processing device, which will be described later, to connect a first conductor wire and a second conductor wire for the Y-axis, a third conductor wire and a fourth conductor wire for the X-axis, and a first conductor wire for the Y-axis. a second conductor, and a third conductor and a fourth conductor for the Y-axis.
This is a switching device that sequentially switches the conductive wires and inputs the output signal of each of these conductive wires. 7 and 8 are amplifiers that amplify the signal input from the switch 6; 9 is an integrator that integrates the signal on one of the conductors, for example, the first conductor of the first conductor and the second conductor; and 10 is an amplifier This is an adder that adds the output signals of 8 and integrator 9.

A waveform converter 11 converts the output signal of the adder 10 into a pulse signal having the same phase as the output signal of the adder 10. 12
is a phase comparator, which detects the phase difference between the rising edge of the pulse output from the counter 2 and the rising edge of the pulse output from the waveform converter 11. Reference numeral 13 denotes a data processing device that calculates coordinate values and performs other processing and control based on the phase difference detected by the phase comparator 12.

The coordinate detection operation of the pointing device with such a configuration is detailed in the above-mentioned publication, so the explanation will be omitted.

[Problem that the invention seeks to solve]

In the above-mentioned conventional coordinate detection device, as described above, four X-axis conducting wires and four Y-axis conducting wires are each arranged in a meandering manner on the tablet 5. The overall shape of the wiring of each conducting wire is approximately a rectangular shape consisting of four sides: a wiring start side of the conducting wire, a wiring end side, and both sides formed by the meandering end folds.

In such wiring, if a pointing device is placed near each side, the induced voltage induced in the conductor becomes a distorted sine wave, making accurate coordinate detection impossible. That is, in the approximately rectangular wiring of each conductor, there is an effective area where the coordinates of the indicating device can be accurately detected, and the other area (4)
The coordinate detection values in the area near the two sides cannot be adopted because they are inaccurate and must be excluded.

However, in conventional devices, a means for accurately determining whether or not detected coordinate values are in a valid area has not yet been proposed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a coordinate detection device that can reliably determine whether or not a pointing device is in an effective area.

[Means for solving problems]

In order to achieve the above object, the present invention includes a meandering detection lead wire, a coordinate indicator that generates a magnetic field, and a coordinate indicator based on the voltage induced in the detection lead wire by the coordinate indicator. A coordinate detection device comprising a control unit that detects the coordinates of an indicator, a determination conductor that surrounds an area outside the detection effective area constituted by the detection conductor, and a determination conductor that is induced by the coordinate indicator. The present invention is characterized by further comprising a determining means for determining whether or not the coordinate indicator is in the detection effective area based on the output.

[Effect]

When the coordinate indicator is placed in an area surrounded by the determination conducting wire (an area outside the effective detection area), a voltage is induced in the determining conducting wire. This voltage has a phase difference of 180 degrees from the voltage induced in the determination lead when the coordinate indicator is placed in the effective area. This results in
It can be determined whether the detected coordinate values are valid or invalid, or whether detecting the coordinate values is valid or invalid.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 1a is a wiring diagram of a coordinate detection device according to an embodiment of the present invention, and FIG. 1b is a sectional view taken along line Ib-Ib shown in FIG. 1a. In each figure, 5' indicates the tablet of this embodiment. Reference numeral 19 denotes an insulating substrate constituting the tablet 5', which is indicated by a dashed line. 2
0 is a conductive wire laid out on the insulating substrate 19. As mentioned above, there are a total of 8 conductive wires to be wired,
In the figure, the damage to one conductor 20 is shown, and illustration of other conductors is omitted. 20s and 20e indicate the starting edge and the terminal edge of the conducting wire 20, respectively, and 20f indicates the folded edge of the conducting wire 20.

Reference numeral 21 denotes a determination conducting wire provided in this embodiment, which is wired on the insulating substrate 19 insulated from other conducting wires. The determination conducting wire 21 is shown as a thick line. Reference numeral 21u denotes an outer edge line of the determination conducting wire 21, which is wired along the outer edge of the insulating substrate 19. 2
1i is an inner edge line of the conducting wire 21 for determination. Circle line 2
1i is wired on the periphery of the effective area on the tablet 5'. That is, the area A surrounded by the inner edge line 21i is a valid area, and the other area B is an area where coordinate detection should be invalidated. Area B is the outer edge line 21
It is surrounded by u and the inner edge line 21i.

FIG. 2 is a waveform diagram of the induced voltage induced in the determination conducting wire 21 shown in FIGS. 1a and 1b.
The induced voltage is plotted on the vertical axis. When the indicating device is placed in the vicinity of the inner edge line 21i in the effective area A, an induced voltage V _A is generated at both ends of the determination conducting wire 21 according to the position in the vicinity, but at other positions in the effective area A The induced voltage becomes 0. Further, when the indicating device is placed outside the outer edge wire 21u, an induced voltage V _C is generated at both ends of the determination conducting wire 21.
The induced voltage V _C is in phase with the induced voltage V _A.

On the other hand, when the indicating device is placed in the area B surrounded by the outer edge line 21u and the inner edge line 21i, there is a voltage at both ends of the determination conductor 21 that is out of phase with the induced voltage V _A.
Induced voltages V _B that differ by 180 degrees are generated. In this embodiment, it is determined whether the indicating device is in the effective area A by looking at the phase of the induced voltage in the determining conductor 21. In this embodiment, the outer edge wire 21u of the determination conducting wire 21 is wired along the outer edge of the insulating substrate 19, and the indicating device is placed at the outer edge of the insulating substrate 19 or at a position outside the outer edge of the insulating substrate 19. The induced voltage V _C can be ignored since it is never placed at

Next, the determination operation of this embodiment will be explained with reference to FIG. FIG. 3 is a block diagram of a coordinate detection device using the tablet 5' shown in FIGS. 1a and 1b.
In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and explanations thereof will be omitted. 5' is the same tablet as the tablet 5' shown in FIGS.
1E is a ground wire.

When the pointing device is placed at a position away from the inner edge line 21i of the effective area A, its coordinate values are calculated by normal processing. After the coordinate values are calculated, the data processing device 13 outputs a switching command to the switch 6 and connects the output line 21L to the amplifier 7 and the ground line 21E to the amplifier 8. In this case, the induced voltage output from the output line 21L is 0, so
The output from the waveform converter 11 also becomes 0, making comparison by the phase comparator 12 impossible. The data processing device 13 looks at this, determines that the pointing device is in the effective area A, and adopts the previously calculated coordinate values.

Next, when the indicating device is near the inner edge line 21i of the effective area A, after the coordinate values are calculated, the induced voltage V _A of the determination conductor 21 inputted through the output line 21L is Similarly, it is converted into a pulse by the waveform converter 11, and the phase comparator 12
It is compared with the output pulse of counter 2, and both have the same phase. The data processing device 13 looks at this, determines that the pointing device is in the effective area A, and adopts the previously calculated coordinate values.

Next, when the indicating device is in region B, after its coordinate values are calculated, the induced voltage V _B of the determination conductor 21 is inputted via the output line 21, converted to a pulse by the waveform converter 11, and phase comparison is performed. The phase difference with the pulse output from the counter 2 is compared in the device 12.

As described above, in this case, the induced voltage in the determination conducting wire 21 has a phase different by 180 degrees from the phase of the excitation current for the indicating device (the phase of the output pulse of the counter 2). Therefore, this phase difference is determined by the phase comparator 12.
Based on this, the data processing device 13 performs a process of eliminating coordinate values that have already been calculated and not adopting them as coordinate values. This completely prevents the output of inaccurate coordinate values.

In this way, in this embodiment, the area outside the valid area is surrounded by the determination conductor, and the output of the determination conductor is used to determine whether or not the coordinate indicator is placed in the valid area. , the determination can be made reliably, and the output of inaccurate coordinate values can be prevented.

In the description of the above embodiment, a coordinate detection device is exemplified in which two types of conductive wires are laid at different pitches for each coordinate axis, and the coordinates are calculated by determining the phase difference based on the outputs of these conductive wires. The method is not limited to this, and can be applied to any other method. In addition, in the description of the above embodiment,
We have described an example in which the coordinate values are first detected and then it is determined whether or not they are in the valid area. It is clear that when it is determined that the detection of coordinate values thereafter may be stopped. Furthermore, in the description of the above embodiment, the outer edge line of the determination conductor is wired close to the outer edge of the tablet, but it is unlikely that the coordinate indicator will be placed far outside the effective area. In consideration of this, it is not necessarily necessary to wire the outer edge line almost to the outer edge of the tablet.

〔Effect of the invention〕

As described above, in the present invention, the area outside the effective area is surrounded by a determination conducting wire, and it is determined whether or not the coordinate indicator is in the effective area based on the output of this determining conducting wire. This determination can be made accurately, and the output of inaccurate coordinate values can be reliably prevented.

[Brief explanation of drawings]

Figures 1a and 1b are wiring diagrams and cross-sectional views of the tablet used in the coordinate detection device according to the embodiment of the present invention, and Figure 2 is the induced voltage of the determination conductor shown in Figure 1a and b. FIG. 3 is a block diagram of the coordinate detection device according to the embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional coordinate detection device. 5'...Tablet, 11...Waveform converter, 1
2... Phase comparator, 13... Data processing device, 1
9...Insulating board, 21...Conducting wire for determination.

Claims (1)

[Claims] 1. A detection lead wire laid in a meandering pattern, a coordinate indicator that generates a magnetic field, and a control unit that detects the coordinates of the coordinate indicator based on the voltage induced in the detection lead wire by the coordinate indicator. In the coordinate detecting device, the coordinate indicator is configured to detect the coordinates based on a determination conductor that surrounds an area outside the detection effective area, which is constituted by the detection conductor, and an output of the determination conductor induced by the coordinate indicator. 1. A coordinate detection device characterized by comprising a determining means for determining whether or not the coordinate detection device is in a detection effective area.