JPH0519943A - Coordinate input device - Google Patents

Abstract

PURPOSE:To accurately calculate coordinates even at the peripheral part of a sense line group. CONSTITUTION:A correcting sense line 1 is laid at the peripheral parts of first and second sense line groups S1 and D2, and the exciting current control means of the correcting sense line 1 is provided. Further, the correcting sense line 1 is excited with the reverse phase of the first sense line group S1. A guide signal to be the cause of error in the case of calculating the coordinates is generated at the peripheral part of the first or second sense line group S1 or S2. By controlling the exciting current of the correcting sense line 1 according to the position of a selected sense line, this guide signal is attenuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for inputting coordinates to an information processing device such as a computer, and more particularly to a coordinate input device to which an electromagnetic induction phenomenon is applied.

[0002]

2. Description of the Related Art As a conventional coordinate input device, there is JP-A-2-249919 invented by the present applicant. In this coordinate reading device, the resonance circuit of the coordinate indicator resonates by the alternating magnetic field generated from the first sense line group of the two sense line groups laid along each of the XY orthogonal coordinate axes, and Utilizing the fact that the induction signal is induced in the second sense line group by the alternating magnetic field generated from the resonating coordinate indicator, the induction detected at that time according to the positions of the selected first and second sense lines. The position of the coordinate indicator, that is, the coordinate is obtained by comparing the amplitudes of the signals.

[0003]

Since the first sense line group and the second sense line group are basically orthogonal to each other, the second sense is generated by the alternating magnetic field generated from the first sense line group. No direct induction signal is generated in the line group, but a direct induction signal is generated when a peripheral sense line in the first or second sense line group is selected.

FIG. 8 is an explanatory view for explaining a state of induction between the first sense line group and the second sense line group,
A sense line yk including a qrst unit that generates a magnetic field
And one sense line xk including a uvwx section for detecting an induction signal. Further, the symbol indicating the direction of the magnetic field shown in the figure is q indicated by an arrow on the sense line yk.
This is when a current flows in the direction of rst. As shown in FIG. 8, the distances ly1 and ly2 and the distances lx1 and l
If x2 is sufficient, the sum of the flux linkage numbers of the sense line xk becomes almost zero even if there is a magnetic field generated from the sense line yk, so that induction by the magnetic field generated from the sense line yk does not occur. However, the distances ly1 and ly
If either 2 or the distances lx1 and lx2 are short, the condition that the number of interlinkage magnetic fluxes becomes zero cannot be satisfied. For example, when the distance ly1 in FIG. 8 is short, there is a portion of the magnetic field generated from the sense line yk above the qr portion (the magnetic field in the front to back direction on the paper surface) that does not intersect the sense line xk. Will increase. Further, when the distance lx1 is short, it is affected by the magnetic field generated from the rs portion of the sense line yk (the magnetic field in the front direction from the back of the paper).
Therefore, the distances ly1 and ly2 or the distances lx1 and l
If any of x2 is short, the number of interlinkage magnetic fluxes does not become zero, and an induction signal due to the magnetic field generated from the sense line yk is generated in the sense line xk. For this reason, in the peripheral portion of the sense line group, an induction signal due to an influence from other than the coordinate indicator, that is, an induction signal generated by the coupling between the two sense line groups. This will result in an error.

Further, in order to reduce this induction signal,
In the peripheral part of the sense line group, the distances ly1 and ly are set.
If 2 or the distances lx1 and lx2 are made long, the size of the entire sense line group becomes large and the coordinate input device itself becomes unnecessarily large. An object of the present invention is to improve such a conventional drawback, and to provide a coordinate input device capable of performing accurate coordinate calculation even in the peripheral portion of the sense line group of the coordinate input device.

[0006]

A coordinate indicator having a resonance circuit composed of at least a coil and a capacitor, and a first sense line having a plurality of sense lines laid parallel to one of the XY orthogonal coordinate axes. Group, a second sense line group having a plurality of sense lines laid parallel to the other axis, a first scanning circuit for sequentially selecting the first sense line group, and the first scanning circuit An exciter circuit connected to and exciting the first sense line group;
A second scanning circuit which sequentially selects the second sense line group; an induction signal detection circuit which is connected to the second scanning circuit and detects an induction signal induced in the second sense line group; In a coordinate input device including a control circuit for obtaining coordinates from the induction signal detected by the induction signal detection circuit, a correction sense line and a correction sense line in the periphery of the first and second sense line groups are provided. Excitation signal control means is provided, and the correction sense line is excited in a phase opposite to that of the first sense line group.

[0007]

[Operation] In the coordinate input device according to the present invention, when a peripheral sense line in the first or second sense line group is selected, an induction signal is generated due to coupling between the two sense line groups. Since the induction signal is attenuated by the magnetic field generated from the line, the coordinates can be accurately calculated even in the peripheral portion of the sense line group.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a block diagram of a coordinate input device according to the present invention. In the figure, 1 is a correction sense line, S1
Is a first sense line group having sense lines y1 to yn, S2 is a second sense line group having sense lines x1 to xm, 2 is a first scanning circuit for sequentially selecting the first sense line group S1, Reference numeral 3 is a second scanning circuit that sequentially selects the second sense line group S2, and 4 is an exciting circuit that excites the first sense line group S1 and the correction sense line 1, and controls the excitation signal 43 of the correction sense line 1. An excitation signal control means is provided, 5 is an induction signal detection circuit for detecting an induction signal generated in the second sense line group S2, 6 is a control circuit composed of a general CPU circuit, and 7 is a resonance circuit (illustrated). Not). It should be noted that the sense lines in the figure are shown in a simplified manner in order to avoid making the figure complicated.

FIG. 2 shows a detailed view of the sense line. The symbols in the figure are the same as those in FIG. FIG. 3 shows an explanatory diagram of the effect of the correction sense line 1. Excitation circuit 4 in FIG.
The circuit diagram of is shown. FIG. 5 is a diagram showing the control value (decimal display) of the control signal 44 for controlling the excitation signal control means of the correction sense line 1.

FIG. 6 is a diagram showing an induction signal generated by coupling between two sense line groups according to this embodiment. FIG. 7 is a diagram showing an induction signal generated by coupling between two conventional sense line groups. The operation of this embodiment will be described below. In FIG. 1, the first sense line group S1 is sequentially selected and excited by the first scanning circuit 2. The coordinate indicator 7 is the first sense line group S.
When approaching 1, the resonance circuit of the coordinate indicator 7 resonates due to the alternating magnetic field generated from the first sense line group S1,
An induction signal is induced in the sense line group S2 by the alternating magnetic field generated from the resonated coordinate indicator 7. The induction signal is subjected to predetermined processing by the induction signal detection circuit 5 and input to the control circuit 6. The control circuit 6 obtains the position of the coordinate indicator, that is, the coordinates by comparing the amplitudes of the induction signals detected at that time according to the positions of the selected first and second sense lines. The details of the operation and the coordinate calculation method described above are described in Japanese Patent Application Laid-Open No. 2-249019, and a further description will be omitted here.

Next, details of the correction sense line 1 will be described. FIG. 2 is a detailed view of the sense line groups S1 and S2 and the correction sense line 1 of the embodiment shown in FIG. 1, and the correction sense line 1 includes the first sense line group S1 and the second sense line group S2. It is laid in the peripheral area.
First, the effect of the corrected sense line 1 in the peripheral portion of the first sense line group S1 will be described. FIG. 3A is an enlarged view of a portion A of FIG. 2 and shows one sense line for each of the first sense line group S1 and the second sense line group S2. When a current is flowing in the sense line yn of the first sense line group S1 in the direction of the arrow, a magnetic field from the upper side to the lower side of the paper is inside the loop of the sense line yn, and a magnetic field from the upper side to the front side is outside the loop. The magnetic field from the back to the back is generated. In this case, the sense line xj of the second sense line group S2 does not cross the magnetic field generated from the sense line yn with the magnetic field outside the folded portion of the sense line xj (from the front side to the back side of the drawing). A minute induction signal will be generated. At this time, when a predetermined current is applied to the correction sense line 1 in the direction of the arrow, a magnetic field is generated from the front side to the back side of the drawing on the inside of the correction sense line 1, that is, on the sense line xj side. Therefore, the sense line y
Among the magnetic fields generated from n, the magnetic field that does not intersect with the sense line xj can be supplemented by the correction sense line 1, and the induction signal generated in the sense line xj can be attenuated.

Next, the effect of the corrected sense line 1 in the peripheral portion of the second sense line group S2 will be described.
FIG. 3B is an enlarged view of part B of FIG. 2, and shows one sense line for each of the first sense line group S1 and the second sense line group S2. When a current is flowing in the sense line yj in the direction of the arrow, a magnetic field from the front side to the front side of the paper is generated inside the loop of the sense line yj, and a magnetic field from the front side to the back side of the paper is generated outside the loop. ing. In this case, in the sense line x1, the magnetic field generated from the sense line yj intersects with the magnetic field from the folded portion of the sense line yj (from the top to the back of the paper), and the induced signal is generated accordingly. At this time, when a predetermined current is applied to the correction sense line 1 in the direction of the arrow, a magnetic field is generated from the front to the back of the drawing on the inside of the correction sense line 1, that is, on the side of the sense line x1. Therefore, of the magnetic fields generated from the sense line yj, the magnetic field intersecting with the sense line x1 can be canceled by the correction sense line 1, and the induction signal generated in the sense line x1 can be attenuated. As is clear from the above description, FIG.
In either case, the correction sense line 1 has a current flowing in the opposite direction to the current flowing through the first sense line group S1.
That is, the induction signal generated in the sense line x1 can be attenuated by generating a magnetic field having a phase opposite to that of the first sense line group S1.

FIG. 4 shows a circuit diagram of the exciting circuit 4. Figure 4
Indicates the final stage of the excitation circuit, which is composed of a well-known operational amplifier. The excitation signal 41 is obtained by converting the excitation signal 40 output from the control circuit 6 into a sine wave. The excitation signal 41 is amplified to a predetermined voltage by the operational amplifier U1 and passed through the current limiting resistor R1 to the first scanning circuit 2
Is output as an excitation signal 42 to the operational amplifier U
2 is amplified to a predetermined voltage by the current limiting resistors R2 to R5
And a multiplexer U3 (for example, uPD4 manufactured by NEC)
051) to the excitation signal 43 to the correction sense line 1
Is output to excite the correction sense line 1. The multiplexer U3 controls the magnitude of the excitation signal 43 (excitation current) output to the correction sense line 1, and the excitation signal 43 is controlled in 5 steps by the 3-bit control signal 44 output from the control circuit 6. To be done. Current limiting resistor R2
The resistance values of R5 to R5 are set as R2>R3>R4> R5, and the values of the control signal 44 are 0, 1, 2, 3, 4 (10
The exciting current value of the correction sense line 1 is increased as it increases. When the value of the control signal 44 is 0, the excitation signal 43 becomes zero.

The control signal 44 is determined based on the position of the selected sense line of the sense line groups S1 and S2. This is because the magnitude of the induced signal generated by the coupling between the two sense line groups differs depending on the position of the selected sense line, and the influence of the magnetic field generated by the correction sense line 1 is the first sense line. Group S1
This is because there is a difference between the case of the peripheral part of the above and the case of the peripheral part of the second sense line group S2. For example, in the case of the peripheral portion of the first sense line group S1, as shown in FIG. 3A, mainly the folded portion of the sense line x is the corrected sense line 1 only.
Is affected by the magnetic field generated by. However, in the case of the peripheral portion of the second sense line group S2 shown in FIG. 3B, it is affected by the magnetic field generated by the correction sense line 1 over substantially the entire length of the sense line x, and this effect is the case described above. Greater than. Therefore, it is necessary to change the excitation signal 43 of the correction sense line 1 between the case shown in FIG. 3A and the case shown in FIG. 3B. Further, for example, in the case of exciting the sense line yn in FIG. 3A and in the case of exciting the sense line yn-1 which is laid next to the sense line yn (not shown), the sense line y is excited.
Since n-1 is wider than the sense line yn with respect to the folded portion of the sense line xj, the induction signal generated in the sense line xj becomes smaller. 3B, when the sense line yj is excited, the sense line x1 is selected and the sense line x1 is not shown.
When the sense line x2 laid next to the sense line x2 is selected, the sense line x2 is the sense line x1.
Since the gap between the sense line yj and the folded portion is wider, the induced signal generated when the sense line x2 is selected is smaller.

As described above, the magnitude of the induction signal generated by the coupling between the two sense line groups differs depending on the position of the selected sense line, and the influence of the magnetic field generated by the correction sense line 1 is the first. The control signal 44 is determined based on the position of the selected sense line of the sense line groups S1 and S2 because it is different in the peripheral portion of the first sense line group S1 and in the peripheral portion of the second sense line group S2. There is a need to.

FIGS. 5 to 7 show the results of experiments conducted by providing the conventional coordinate input device with the correction sense line 1 and the excitation circuit 4 shown in the above embodiment. The sense line used in the experiment is the first sense line group S1 that generates a magnetic field.
20 and 28 second sense line groups S2 are laid. That is, in FIG. 1, the sense line yn is y2.
0 when the sense line xm becomes x28.
FIG. 5 shows the control value (decimal notation) of the control signal 44 for controlling the excitation signal 43 flowing through the correction sense line 1. Figure 5
1 to 20 on the S1 side shown in FIG.
1 and corresponds to the sense lines y1 to yn in FIG. S
1 to 28 on the second side indicate the second sense line group S2 and correspond to the sense lines x1 to xm in FIG. FIG. 5 means, for example, that the value of the control signal 44 is 4 when the sense line y1 and the sense line x2 are selected, and the value of the control signal 44 is 2 when the sense line y2 and the sense line x3 are selected. To do. Further, the blank portion indicates that the value of the control signal 44 is 0, and the excitation signal 43 of the correction sense line 1 becomes zero. FIG. 6 shows an induction signal generated by coupling between two sense line groups according to the present embodiment, and shows the magnitude of the induction signal when the control signal 44 is controlled as shown in FIG. 5, that is, the induction voltage. . FIG. 7 shows an induction signal generated by the conventional coupling between two sense line groups, that is, the excitation signal 4 is completely present in the correction sense line 1.
It is an induced voltage when 3 is not applied. The vertical axes of FIGS. 6 and 7 indicate the magnitude of the induction signal, and the vertical scales are the same in both cases. As can be seen from FIG. 7, a particularly large induced voltage is generated when the sense line y1, y20, x1 or x28 is selected.
By causing the multiplexer U3 to control the multiplexer U3 with a predetermined current and causing a predetermined current to flow through the correction sense line 1, it is generated in the peripheral portion of the sense line group S1 or S2 due to the coupling between the two sense line groups that causes an error in coordinate calculation. The induced signal could be greatly attenuated as shown in FIG.

In the embodiment shown in FIG. 4, since the excitation signal 42 and the excitation signal 43 are in-phase signals, the correction sense line 1 should be wound in the opposite direction to the first sense line group S1. Thereby, a magnetic field having a phase opposite to that of the sense line group S1 can be generated from the corrected sense line 1. Although the operational amplifier U2 is used in the embodiment shown in FIG. 4, if there is a margin in the current capacity of the operational amplifier U1, the multiplexer U3 is directly connected to the output of the operational amplifier U1 and the operational amplifier U2 is omitted. I don't care. Further, in the embodiment of the exciting circuit 4 shown in FIG. 4, the operational amplifier U2 is configured as an inverting amplifier, the exciting signal 43 is in the opposite phase to the exciting signal 42, and the correction sense line 1 is wound in the first sense line group. Even if the direction is the same as that of S1, the same effect of the corrected sense line 1 can be obtained.

FIG. 9 shows a detailed view of a sense line according to another embodiment. In the above embodiment, the correction sense line 1 is shown in FIG.
Although it is laid on the outer circumference of the folded portion of the sense lines of the sense line groups S1 and S2 as shown in FIG. 9, the same effect of the corrected sense line 1 can be obtained by laying it inside as shown in FIG. In the above embodiment, the sense line group S
Although the case where the number of turns of the sense lines of S1 and S2 and the correction sense line 1 is one turn has been described, it goes without saying that the number of turns is not limited to the above number due to the principle described above.

[0019]

As described above, according to the present invention, the correction sense line and the excitation signal control means for the correction sense line are provided in the peripheral portion of the first and second sense line groups, and the correction sense line is the first. By being excited in a phase opposite to that of the first sense line group, the induction signal generated by the coupling between the two sense line groups, which causes an error in coordinate calculation, can be attenuated, and the sense line group can be attenuated. It is possible to provide a coordinate input device that accurately calculates coordinates in the peripheral portion of the sense line group without increasing the size of the coordinate input device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a detailed view of a sense line.

FIG. 3 is an explanatory diagram of an effect of a correction sense line.

FIG. 4 is a circuit diagram of a scanning circuit.

FIG. 5 is a diagram showing a control value (decimal display) of a control signal 44.

FIG. 6 is a diagram showing an induction signal generated by coupling between two sense line groups according to the present embodiment.

FIG. 7 is a diagram showing an induction signal generated by coupling between two conventional sense line groups.

FIG. 8 is an explanatory diagram of induction between two sense line groups.

FIG. 9 is a detailed view of a sense line according to another embodiment.

[Explanation of symbols]

 1 Correction Sense Lines 2 and 3 Scanning Circuit 4 Excitation Circuit 5 Induction Signal Detection Circuit 6 Control Circuit 7 Coordinate Indicator S1 First Sense Line Group S2 Second Sense Line Group

Claims (1)

Claim: What is claimed is: 1. A coordinate indicator having a resonance circuit composed of at least a coil and a capacitor, and a first sense line having a plurality of sense lines laid parallel to one of the XY orthogonal coordinate axes. A sense line group; a second sense line group having a plurality of sense lines laid parallel to the other axis; a first scanning circuit for sequentially selecting the first sense line group; An exciting circuit connected to a scanning circuit for exciting the first sense line group, a second scanning circuit for sequentially selecting the second sense line group, and a second scanning circuit connected to the second scanning circuit. In a coordinate input device comprising an induction signal detection circuit for detecting an induction signal induced in the sense line group, and a control circuit for obtaining coordinates from the induction signal detected by the induction signal detection circuit, A correction sense line and an excitation signal control means for the correction sense line are provided on the periphery of the first and second sense line groups, and the correction sense line is excited in a phase opposite to that of the first sense line group. A coordinate input device for correcting the guidance signal.