JPS5818667B2 - coordinate reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coordinate reading device in which the linearity of the generated phase at the end of a coordinate reading device plate (tablet) is improved.

The coordinate reading device according to the present invention has a coordinate reading device plate that generates an alternating magnetic field whose phase differs depending on the position on a plane. It knows the position on the reader board.

FIG. 1 is an explanatory diagram showing the configuration of a conventional coordinate reading device.

In the figure, reference numeral 1 indicates a coordinate reading device board (tablet), on which a large number of coils 3, . 3 2.・・・・・・
. . , has a structure in which 3-N are arranged.

Each coil 3, . 3 2. ..., 3-N are independent AC power supplies 4 1, 4 2. ...... Excited by 4N.

Reference numeral 5 denotes a position detector having a detection coil 6, which, when placed on the coordinate reading device board 1, generates an alternating current voltage or current by combining with an alternating magnetic field at that position.

The output of the position detector 5 is applied to a phase detector 7 and compared with a reference phase signal from a reference phase input terminal 8 to produce a voltage or current depending on its phase.

The processing device 9 converts the output signal of the phase comparator 7 into a signal, for example, a digital signal, depending on the purpose of use, and outputs the converted signal to the output terminal 1.
Output to 0.

FIG. 2 is a perspective view showing an example of the structure of the coordinate reading device plate in the apparatus shown in FIG. 1.

In the same figure, reference numeral 2 indicates a flat plate made of an insulator, and coils 3 1, 3 . 2.
..., 3-N are arranged at equal intervals between the widths A in the X direction.

In the coordinate reading device board of FIG. 2, each coil 3-1, 3
2. ..., AC power supply 4 for each 3-N
-1,4-2. ..., 4-N is el, e2 t..., en, and any voltage en is determined by the following equation in relation to the amplitude and phase angle. do.

e −A 5ln(ωt+φn) Origin n A, = constant (1)-1 φ”=N-1” Here, ω=2πf (f is the frequency of the AC power source).

That is, each coil is excited by a respective power source with equal amplitude and sequentially with equal phase difference.

FIG. 3 is a diagram showing the distribution of magnetic field and phase on the coordinate reader plate of FIG. 2.

Figure 3a shows the magnetic field of each coil.

In the same figure, H is the magnetic field, H, x * HY are each X
and the magnetic field components in the X direction, showing that all coils generate only a magnetic field in the X direction, and that the amplitudes are all equal.

When coils arranged at equal intervals in this manner are excited with equal phase intervals by power supplies of equal amplitude, the resultant magnetic field produces a phase distribution that changes linearly over a certain range.

FIG. 3 shows the phase distribution of the composite magnetic field, and its X coordinate corresponds to FIG. 3a.

As seen in the figure, with respect to the width A where the coil is arranged, in the central part 1, the phase change of the magnetic field Hy changes linearly with the change in position in the X direction, but at both ends. 2 and 3 are off the straight line.

In the case of the arrangement and excitation of the coil as shown in FIG. 2, the range of the straight section is relatively narrow, typically about 65% of the width A.

The coordinate reading device can read the coordinate position without correction in areas where the magnetic field phase changes linearly, but in other areas, some kind of correction is required for the detection signal, and in order to do so. Equipment becomes more complex.

Further, if it is attempted to be used without correction, a larger coordinate reading device plate will be required, or the accuracy of coordinate reading at the end portions will deteriorate, which is not preferable.

The present invention aims to eliminate such drawbacks of the prior art, and its purpose is to expand the linear range of a coordinate reading device board by improving the linearity of the generated phase at both ends. be.

In order to achieve this object, in the coordinate reading device of the present invention, a plurality of coils arranged on a plane plate generate an alternating magnetic field whose phase differs depending on the position on the plane plate, and the alternating magnetic field is detected by a position detector. A device for reading the coordinates of the position detector on the plane plate based on the phase of the detected alternating current voltage or current, comprising means for changing the current amplitude of the coils arranged on the plane plate for each coil. It is characterized in that the phase of the magnetic field in the direction perpendicular to the plane plate varies linearly with respect to the position on the plane plate.

Examples will be described below.

FIG. 4 is an explanatory diagram showing the configuration of a coordinate reading device plate in an embodiment of the coordinate reading device of the present invention.

In the figure, each coil 3, . 3 2. ......, 3
-N are all equal and equally spaced between the widths A.

Each coil 3-1, 3 2. ..., 3-N are AC power supplies 4mm1, 4jin2, respectively. . . . 42 N, respectively, the voltage e'1. e'2. . . . is excited by being given e(.

In this case, any voltage elr1 has amplitude A/n2 phase angle φ
In relation to □, it shall be determined by the following formula.

In equation (2), the amplitude A/n is determined such that the amplitude in the coils at both end portions gradually decreases compared to the coil at the center portion.

By doing so, the linearity of the phase change at both end portions can be improved and the linear portion can be expanded.

Table 1 shows an example of → film width A'r1 in the case of 9 phases (N29) selected to give the best result.

FIG. 5 is a diagram showing the phase distribution of the composite magnetic field of the coordinate reading device plate in one embodiment of the coordinate reading device of the present invention, in which the coordinate reading device plate shown in FIG. This shows the case where the amplitude of the power supply is determined.

In the case of Figure 5, the range in which the phase change is linear is approximately 85%.
It can be seen that this is clearly improved compared to the case shown in Figure 3.

Note that in the case of the present invention, the ripple in the portion where the phase changes linearly is also reduced compared to the conventional case, to less than half.

This ripple is actually a very small value.

FIG. 6 is an explanatory diagram showing the structure of a coordinate reading device plate in another embodiment of the coordinate reading device of the present invention.

In the figure, each coil 3L1, 3L2. ......, 3
LN are arranged at equal intervals between the widths A, and the AC power supplies 4, . 4-2. ..., by 4-N,
They are each given a % pressure e1t e2 , . . . , eN and are excited.

Here, the voltage e1. e2 +..., eN is (1)
It is defined by Eq.

However, in the field of the embodiment shown in FIG. 6, each coil 3L1, 3L2 . ..., 3iN are not equivalent, and by selecting the wire riw and wire length, each coil can have an arbitrary resistance value, thereby limiting the current amplitude of the coil.

That is, this allows the distribution of current amplitude in each coil to be determined, for example, as shown in Table 1, and therefore the same effect as in the embodiment shown in FIG. 4 can be obtained.

In the case of the embodiment shown in FIG. 6, the wire width and wire length of each coil can be easily selected by selecting the shape of the printed pattern on the coordinate reader board; in this case, each AC power source is Since it is sufficient to have the same amplitude, there is an advantage that manufacturing is easier than in the case of the embodiment shown in FIG. 4. Instead of changing the resistance by changing the width and wire length, it is also possible to make all the coils the same, add a resistance externally, and change the value of this resistance to limit the current amplitude of the coil.

The coordinate reading device of the present invention can be applied not only to the one-dimensional case described in the above embodiment but also to the two-dimensional case.

In this case, it goes without saying that the apparatus of the present invention may be used two-dimensionally.

In Table 1, a specific example is shown for the case of nine phases, but the present invention can be applied to any case having a plurality of arbitrary phases.

Further, the changing phase range is limited to π, but may be any angle within 2π.

As explained above, according to the coordinate reading device of the present invention,
Since the range of linear phase change in the magnetic field generated by the coordinate reader plate can be expanded, the coordinate reading accuracy at the edge of the coordinate reader plate can be improved, and if the accuracy is the same, the coordinate reading This is advantageous because the device plate can be made smaller.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the configuration of a conventional coordinate reading device;
The figure is a perspective view showing an example of the structure of the coordinate reader plate, FIG. 3 is a diagram showing the distribution of magnetic field and phase on the coordinate reader plate of FIG. 2, and FIG. 4 is an embodiment of the coordinate reader of the present invention. 5 is a diagram showing the phase distribution of the composite magnetic field on the coordinate reader plate shown in FIG. 4, and FIG. 6 is an explanatory diagram showing the configuration of the coordinate reader plate of the present invention It is an explanatory view showing the composition of the coordinate reading device board in an example. 1: Coordinate reading device board, 2: Plane board, 3, . 3-2゜・
・・・・・・ 3 3'3' ,, -,,
3'N Nikoil, Fu-N9-1t 2u41,. 4-2...* 4-'N, 4'-1
, 4'-2t・song・, 4'-N: AC power supply, 5: Position detector, 6: Detection Koinogu 7: Phase detector, 8: Reference phase long sword terminal, 9: Processing device, 10: Output terminal.

Claims (1)

[Claims] 1. An AC voltage or In a device for reading the coordinates of the position detector on the plane plate based on the phase of the current, means is provided for changing the current amplitude of the coils arranged on the plane plate for each coil, and A coordinate reading device characterized in that the phase of a magnetic field changes linearly with respect to the position on a plane plate. 2. The coordinate reading device according to claim 1, wherein the change in the current amplitude of the coil is obtained by changing the voltage of an AC power supply supplied to the coil for each coil. 3. The coordinate reading device according to claim 1, wherein the change in the current amplitude of the coil is obtained by changing the resistance of the coil for each coil. 4. The coordinate reading device according to claim 3, wherein the resistance change of the coil is obtained by changing the line width and/or line length of each coil.