JP2858459B2 - Electromagnetic induction tablet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tablet for reading a coordinate position on a plane, and more particularly to an electromagnetic induction tablet utilizing an electromagnetic induction phenomenon.

[Conventional technology]

There are various types of electromagnetic induction tablets that utilize the electromagnetic induction phenomenon.
This is an apparatus disclosed in Japanese Patent Application No. 63-199668.

FIG. 2 is a configuration explanatory diagram showing a general configuration of this device.

This device sequentially supplies alternating current to a predetermined drive line of the drive line group 1 via a drive line scanner 3 and supplies the same.
While the alternating current is being supplied to each of the drive lines, the sense line scanner 4 is sequentially switched. When the position indicator 6 is positioned near the drive line where the AC current is driven, an action magnetic field (a so-called reflected magnetic field) is generated in the coil 61 of the position indicator 6 in accordance with the AC current. I do. This operating magnetic field acts on the sense line group 2 to generate an induced voltage on a predetermined sense line.

The induced voltage is guided to the processing circuit 51, and the position indicated by the position indicator 6 is determined.

[Problems to be solved by the invention]

In this type of apparatus, for example, the drive line scanner 3 is connected to the first drive line, and supplies an alternating current for a predetermined time (for example, T1). During this period, the sense line scanners 4 are sequentially driven to detect whether a predetermined level of voltage is induced in each sense line. In this case, for example, t1 is required as the detection time for each of the sense lines.

Now, assuming that the number of drive lines is N and the number of sense lines is M, and all the drive lines and all the sense lines are switched by the respective scanners 3 and 4, N × T1 (however, T1> M × t1)... (1)

In order to form a tablet having a wide reading surface while maintaining the required accuracy in this type of apparatus, it is necessary to increase the number of drive lines and sense lines, and the processing time increases accordingly, and There was a disadvantage that the speed was reduced.

In this case, in the switching process, there is a configuration in which the thinning process is performed at an appropriate interval, but it is not sufficient.

The present invention has been made for the purpose of solving the above problems.

[Means for solving the problem]

For this reason, in the present invention, the drive line scanner specifies which of the drive lines to which the alternating current is supplied, which drive line is generating the working magnetic field in cooperation with the position indicator. A third grit configuration is provided on the reading surface.

[Action]

The drive line scanner 3 selectively connects to the drive lines sequentially and supplies an alternating current to the respective drive lines as in the related art. At this stage, the time T2 for supplying the alternating current to each drive line is sufficiently shorter than the time T1 of the above-described conventional device. The sense line scanner 4 does not operate at this stage.

Assuming that an AC current is supplied to the drive line near the position indicated by the position indicator 6 for a time T2, a voltage exceeding a predetermined level is induced in the third grid structure. By detecting whether or not a predetermined level of induced voltage is generated in the third grid configuration, it is possible to specify a drive line that is close to the position indicated by the position indicator 6.

An alternating current is supplied to each of a plurality of drive line groups before and after including the specified drive line only for a time T1, and
During these periods, the sense line scanners 4 are sequentially connected selectively to detect voltages induced in the sense line groups. The processing in the second stage is the same as the conventional one, and the processing of these detected voltages can be performed in the same manner as the conventional one.

According to the method of the present invention, the processing time is a maximum of (N × T2) + (n × T1) (2) (where n is one of the drive lines before and after the specified drive line) In the case where it is configured to perform the above, it is 3.). Since N >> n and T2 << T1, reading can be performed at a higher speed as compared with the processing time (N × T1) of the conventional device.

〔Example〕

FIG. 1 to FIG. 5 are explanatory views showing one embodiment of the present invention. FIG. 1 and FIG. It is drawn separately to avoid. FIG. 2 shows the same grit structure as that of the conventional device.

In the present invention, the third grit structure 7 shown in FIG. 1 is laminated on the reading surface of the conventional device shown in FIG.

The grit configuration 7 is arranged such that, for example, two grit conductors 71 and 72 are folded in a zigzag shape to cover the reading surface at a uniform density. The two grid conductors 71 and 72 are also shifted from each other by a half pitch, so that a voltage is induced in one of the grid conductors regardless of the position of the position indicator 6. It is configured as follows. The grit configuration 7 preferably operates by using two or more grit conductors.

The voltage induced in the grid conductor 71 is amplified in a predetermined manner by the amplifier 55, converted into a digital value through the band pass filter 57 via the grid scanner 8, and via the A / D converter 58, and processed as shown in FIG. Input to the circuit 51. Meanwhile, the first
The induced voltage of the grit conductor 72 shown by the broken line in FIG.
6, input to the processing circuit 51 via the grid scanner 8, the band pass filter 57, and the A / D converter 58. In this way, the data obtained from the third grid configuration 7 is subjected to predetermined processing by the processing circuit 51.

 FIG. 3 is an explanatory diagram for explaining a method of this processing.

FIG. 3 (a) shows the third grit configuration 7 shown in FIG.
5 (b) shows the effective value of the induced voltage of the grit conductor 72. FIG. These voltage amplitudes are added in the processing circuit 51 shown in FIG. 2 as shown in FIG. It is determined whether or not the added value (c) is larger than a predetermined level A.

The processing circuit 51 shown in FIG. 2 is the same as the processing circuit 51 shown in FIG.
Grit scanner 8 and drive line scanner 3 shown in FIG.
And the selection connection timing of the sense line scanner 4 is controlled.

Next, the operation of the apparatus of the present invention will be described in the order of processing.

Drive Line Identifying Step It is assumed that the position indicator 6 is at the position shown in FIG.

First, in accordance with a command from the processing circuit 51, the drive line scanner 3
Switches at predetermined time intervals (T2) and connects. Drive line group 1
In each of the drive lines, an alternating current is sequentially driven.

When an alternating current is supplied to a drive line close to the position where the position indicator 6 is located, the coil 61 of the position indicator generates an action magnetic field according to the current. This operating magnetic field generates an induced voltage for the sense line group 4 shown in FIG. 2 and the third grid configuration 7 shown in FIG. 1, but only the grid configuration 7 is processed in this drive line specifying stage. .

In each time interval T2 during which an alternating current is supplied to each drive line of the drive line group 1, the configuration shown in FIG. 1 performs processing as shown in FIG.
Is measured.

In this manner, if an induced voltage by the third grid configuration 7 exceeds a predetermined level A when an AC current is supplied to the drive line shown in FIG. 2I, the position indicator 6
It is determined that it is positioned near this drive line 1i.

Position Determination Step When the drive line near the position indicated by the position indicator 6 is specified, the position determination step is started. In this position determination stage, the third grid configuration shown in FIG. 1 is ignored, and the sense line group shown in FIG. 2 is used.

Now, the drive lines 1i before and after including the specified drive line 1i
Select -1 and 1i + 1. The drive line scanner 3 is first connected to the drive line 1i-1, and supplies an alternating current to the drive line 1i-1 for a predetermined time (T1). During this period, the sense line scanner 4 sequentially connects to the sense lines and measures the voltage induced on each sense line. This measurement data is input to the processing circuit 51 via the sense circuit 54 and is temporarily stored. Similarly, the induced voltages of the respective sense lines for the drive lines 1i and 1i + 1 are measured and stored in the processing circuit 51.

From these measured values, the absolute coordinate value of the position indicator of the position indicator 6 can be obtained. This processing method may be performed similarly to the conventional method.

FIG. 4 schematically shows the procedure of the position determination method, where the drive line identification operation is the position determination operation.

With this operation, a unit reading operation for determining the coordinate position of the position indicator 6 is performed.

By the way, the device of this embodiment utilizes a device in which the frequency of the alternating current supplied to the drive line group changes.

The frequency of the alternating current generated based on the output of the oscillator 52 is varied by the FM modulation circuit 53.

FIG. 5 (a) shows an alternating current whose frequency f is varied by the FM modulation circuit 53. When the switch 62 of the position indicator 6 shown in FIG. 2 is open, the frequency f1 is set, and when the switch 62 is closed,
The two capacitors of the position indicator 6 are selected to be tuned to the frequency f2. FIG. 5B shows the operating magnetic field of the position indicator 6 when the switch 62 is in the open state. It can be seen that a large acting magnetic field is generated at the frequency f1.
Therefore, for example, even in the above-described drive line identification step,
At f1, a voltage is induced in the third grid configuration 7 shown in FIG.

Therefore, at this stage, the third grit configuration 7
By detecting whether the induced voltage is at the frequency f1 or f2, the on / off of the switch 62 of the position indicator 6 can be identified.

As an identification method, a variable frequency AC current supplied to the drive line in advance is
As shown in FIG. 7A, the frequency always increases at the same rate of change from the lowest frequency level, and
There is a counter that starts counting from the point of supply start,
This can be achieved by discriminating whether the point at which the third grid configuration 7 shown in FIG. 1 detects a voltage exceeding a predetermined level is between τ0τ1 and τ1τ2 shown in FIG.

Note that, in the present invention, in a drive line specifying stage or the like, a configuration may be adopted in which selective connections of drive lines and the like are thinned out at appropriate intervals as in the related art. Further, high-speed reading becomes possible.

〔The invention's effect〕

As described above, according to the present invention, as described above, the position indicator specifies the drive line that is close to the position where the position indicator is located, and
Since the position determination operation is performed only on the drive lines around the drive line, the measurement time can be greatly reduced.

[Brief description of the drawings]

1 to 5 are explanatory views showing one embodiment of the present invention. FIGS. 1 and 2 are front views mainly explaining the grit structure of the present invention, and FIG. 3 is shown in FIG. FIG. 4 is a waveform chart illustrating the operation of the third grit configuration, FIG. 4 is a time chart schematically illustrating the position determining operation of the device of the present invention, and FIG. 5 is a time chart illustrating the switch identification operation of the device of the present invention. is there. 1... Drive line group 2... Sense line group 7... Third grid configuration

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 3/03 G06F 3/033

Claims (2)

(57) [Claims] A plurality of drive lines arranged in a first direction, a plurality of sense lines arranged in a second direction, and an AC current selectively supplied to the drive lines. A position indicator for generating an action magnetic field for generating an induced voltage in the sense line group, and processing a voltage signal induced in the sense line group to determine an indicated position of the position indicator. An electromagnetic induction tablet configured to perform a predetermined voltage signal in accordance with an operating magnetic field of the position indicator in proximity to a reading surface on which the drive line group and the sense line group are arranged. And a third grid configuration for specifying a drive line proximate to the position indicated by the position indicator based on the induced voltage signal, and a specified drive line based on the third grid configuration Positioning movement in relation to An electromagnetic induction tablet having a processing circuit for controlling operation. 2. The method of claim 2, wherein the third grid configuration comprises at least two grids.
2. The electromagnetic induction tablet according to claim 1, wherein the conductors are formed so as to be displaced from each other in a zigzag manner.