JPH01211117A - Electromagnetic induction type digitizer - Google Patents

Abstract

PURPOSE:To rapidly execute the position detection of a coordinate indicator and to increase operability by detecting the electromagnetic induction action of a loop coil based on the change of a resonance circuit. CONSTITUTION:When respective loop coils 1i of a loop coil group 1 are scanned by a driving side scanning circuit 5, synchronized to this and the output terminal of respective loop coils 2i of a loop coil group 2 is successively scanned by a detecting side scanning circuit 6, an approximately same level voltage is induced except the vicinity of a coordinate indicator 8 to respective coils 2i. In the vicinity of the indicator 8, when the coil 1i is driven, a coil 8L, which becomes a resonance circuit, is excited together with a capacitor 8C of the indicator 8 and the induced voltage of the coil 2i in the vicinity is influenced. The different output of coils 1i and 2i is inputted to a computer, etc., and the position of the indicator 8 is instantaneously detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic induction digitizer used for coordinate position detection.

[Conventional technology]

Conventionally, a typical electromagnetic induction digitizer used as a coordinate detection device consists of two parallel sets in the A tablet is formed by laying a group of conductors insulated from each other, and a coordinate indicating coil or cursor coil is attached to a cursor (also called a pointer or pen) as a coordinate indicating device that moves close to and parallel to the surface of the tablet. Attachment, apply an alternating current signal of a predetermined frequency to the cursor coil or parallel conductor, detect the parallel conductor in which the maximum electromotive force is induced by electromagnetic induction, or the parallel conductor in which the maximum electromotive force is induced in the cursor coil, There is a system that detects the coordinate position of a cursor and inputs it into a computer or the like.

The principle of such an electromagnetic induction digitizer is explained using Figure 4.The coil inside the cursor (cursor coil)
AC voltage ■ to C. For example, by applying , an alternating current electromotive force is induced. Therefore, by switching the two switches S, , S, and detecting the electromotive force induced in each loop coil X; and Y,
By reading the X and Y loop coils where the electromotive force is maximum, the current position, ie, coordinates, of the cursor coil C or the cursor can be detected.

On the other hand, in addition to the digitizer's original function of detecting coordinates, the coordinate indicator of a digitizer is usually equipped with a switch to selectively instruct a computer, etc., to perform several functions. It should give information that it was pressed (data is often sent in a form that includes position information and switch information. These switches are
It consists of push button switches and switches that are turned on and off by pen strokes.

However, in such an electromagnetic induction digitizer, both when driving the cursor coil C to generate an induced voltage in the loop coil, and conversely when inducing an induced voltage from the loop coil side to the cursor fill, the cursor Cords and cables are required to connect an AC voltage source to coil C, to guide voltage signals from cursor coil C to processing means such as a computer, and to transmit the above switch information. The cables not only obstruct the movement of the cursor, but also have the problem of unavoidable failures such as disconnection or poor contact.

Therefore, in order to solve the above problems, the coordinate indicator (hereinafter referred to as cursor) has a built-in battery, and the drive signal source of the coordinate indicator coil is driven by the battery, making the coordinate indicator cordless. An electromagnetic induction digitizer has been proposed. In this type of cordless coordinate indicator, switch information is inputted by an optical transmission method using a light emitting diode, in which a j-word indicating a selected switch is input, similar to a remote control for a television or the like.

[Problem to be solved by the invention]

However, in the electromagnetic induction digitizer using the conventional cordless coordinate indicator as described above, the coordinate indicator uses a battery, which makes it heavy, and the battery must be replaced quite frequently. Regarding information input, optical transmission methods also have the problem of malfunctions when there is something blocking the light. This invention was made in view of the above circumstances, and its purpose is to
To provide an electromagnetic induction type digitizer that is simple in structure, lightweight, and capable of surely inputting coordinate information and switch information without malfunction using a coordinate indicator that does not require the trouble of replacing batteries.

[Means to solve the problem]

To achieve the above object, the electromagnetic induction digitizer of the present invention has a first configuration that includes a large number of loop coils arranged at equal intervals on the digitizer plate surface and selectively driven by an alternating current signal of a predetermined frequency. The first loop coil comprises a first loop coil group and a large number of loop coils arranged at equal intervals on the digitizer plate surface so that the electromagnetic induction action of each coil of the first loop coil group is approximately equally applied. A second loop coil group electrically insulated from the group, a coordinate indicating coil disposed at the tip, and a capacitor forming a resonant circuit for the predetermined frequency together with the coordinate indicating coil, a movable coordinate indicator; the electromagnetic induction action received by each loop coil of the second loop coil group when each coil of the first loop coil group near the coordinate indicator is driven causes the coordinate indicator to move; This configuration employs a configuration in which the current position of the coordinate indicator is detected by changes due to resonance of the resonant circuit of the coordinate indicator.

Furthermore, in the first configuration, the present invention includes frequency multiplexing means for driving the first loop coil group by multiplexing two or more predetermined frequencies; Two or more of these predetermined frequencies can be selected by switches each having a resonant frequency.
A configuration including three or more resonant circuits is adopted as the second configuration.

[Effect]

In the electromagnetic induction digitizer of the present invention having the above first configuration, when each loop coil of the first loop coil group is driven, each coil of the second loop coil group corresponding to each of these coils receives the same electromagnetic induction effect. However, when the loop coils of the first loop coil group near the coordinate indicator are driven, the coordinate indicator coil receives electromagnetic induction and resonates. Then, due to the resonance of this coordinate indicating coil, the loop coils of the second loop coil group in its vicinity are subjected to electromagnetic induction, so a voltage different from that of the other coils is induced in the loop coil of this specific second loop coil group. be done.

Therefore, the position of the coordinate indicator can be detected by measuring the induced voltage of each coil of the second loop coil group using a known appropriate method.

Next, in the electromagnetic induction digitizer of the present invention having the second configuration, when driving each coil of the first loop coil group, the frequency of the drive signal is multiplexed by the frequency multiplexing means, and the coordinate The detector is equipped with a plurality of resonant circuits each having a plurality of multiplexed frequencies as resonant frequencies, which can be selected by a switch. Then, when a specific switch is closed, resonance occurs in the coordinate indicator only by the specific frequency corresponding to that switch, and the loop coil of the second loop coil group near the coordinate detector resonates with other loop coils. Since a different voltage is induced, it is possible to know the current position of the coordinate indicator, and it is also possible to know which switch is pressed by the frequency that caused the resonance, and the function represented by that switch can be determined by the computer. etc. can be instructed. When no switch is closed, the same resonant circuit as in the first configuration operates in the coordinate indicator, and only the position of the coordinate indicator is detected.

[Embodiments] Hereinafter, embodiments of the electromagnetic induction digitizer of the present invention will be described with reference to the drawings.

An electromagnetic induction digitizer according to an embodiment of the present invention shown in FIG. 1 (ω) has a large number of loop coils 1.(i
= 1 to n; n is a positive integer) Similarly to the first loop coil group 11, the first loop coil group l is placed on the digitizer plate surface.
A large number of loop coils 21 (1=l−n
; n is a positive integer); a second loop coil group 2 which is electrically insulated; an oscillator 3 that generates a sine wave signal of a constant frequency; and an output signal of the oscillator 3 that amplifies Scanning the input terminals of the drive amplifier 4 and each loop coil 11 of the first loop coil group 1 at a predetermined frequency,
The drive-side scanning circuit 5, which is sequentially driven by the output of the drive amplifier 4, scans the output terminals of each loop coil 21 of the second loop coil group 2 in synchronization with the scanning of the drive-side scanning circuit 5, and detects the induced voltage. A device for driving a digitizer plate surface includes a detection side scanning circuit 6, a detection signal amplifier 7 that amplifies the output of the detection side scanning circuit 6 and supplies it to a computer (not shown), a coordinate indicating coil 8L and a capacitor 8C. It is composed of a coordinate indicator 8 that can be moved by hand or manually. The coordinate indicating coil 8L and capacitor 8C of the coordinate indicating device 8 form a resonant circuit whose resonant frequency is the output frequency of the oscillator 3, as shown in the equivalent circuit of FIG. 1(c).

Regarding the operation, each loop coil 11 of the first loop coil group 1 is scanned by the drive-side scanning circuit 5, and the drive amplifier 4
is sequentially driven by the output of the
Each loop coil 2 of loop coil group 2. When the detection-side scanning circuit 6 sequentially scans the output terminals of the detection side scanning circuit 6, 2.
Since the relative positions of the two loop coils are the same,
Each loop coil 2 of the second loop coil group 2. Almost the same level of voltage is induced except in the vicinity of the coordinate indicator 8.

On the other hand, in the vicinity of the coordinate indicator 8, the loop coils 1. When the coordinate indicator 8 is driven, the coordinate indicator 8
Since the coordinate indicating coil 8L forming a resonant circuit with the capacitor 8C is excited under resonance, the induced voltage of each loop coil 21 of the nearby second loop coil group 2 is affected by the action of the resonance energy, and the detection signal For example, a signal as shown in FIG. 3(a) appears on the output side of the amplifier 7, and by removing its high frequency component (output frequency component of the oscillator 3) with a filter (not shown), the signal shown in FIG.
You will get a signal like the one shown below.

Loop coil that produced outputs with such different levels 1. ．． 2. can be easily identified because information such as the number is input into a computer etc. in synchronization with the scanning by the driving side scanning circuit 5 and the detection side scanning circuit 6.
Based on this, the position of the coordinate indicator 8 can be immediately known. Although this embodiment has been explained using an example where only linear coordinates are detected in one direction on the X-Y plane (the vertical direction of FIG. 1 (to)), in reality, the same Another parallel conductor group in the configuration is in the direction orthogonal to the direction shown.
Since the coordinate indicator 8 is provided in pairs, the X-Y coordinates of the coordinate indicator 8 can be known.

The method of forming a loop coil with the parallel conductor groups of the first loop coil group 1 and the second loop coil group 2 is not limited to the method of forming a loop coil with adjacent conductors of the above embodiment, but with each parallel conductor group. On the other hand, a loop coil may be formed by every other parallel conductor or every two or more parallel conductors. Furthermore, the method of scanning each loop coil is not limited to the above embodiment (for example, the first loop coil group 1 and the second loop coil group 2 are divided into several small groups, The loop coils corresponding to each other in the group may be scanned in synchronization.

In the embodiment shown in FIG. 1(a), the output signal (frequency f) of the oscillator 3 and four different frequencies f obtained by multiplying or dividing the frequency based on the output signal (frequency f) of the oscillator 3 are shown in FIG. It is equipped with a frequency multiplexer 9 that multiplexes the signals of f2, f3, and f4 and supplies it to the drive side scanning circuit 5 via the drive amplifier 4, and the coordinate indicator 8 has four function selection switches 81 to S4, and these When each function selection switch S, ~S4 is closed, the coordinate indicating coil 8L
and each of the above frequencies f, , f2, along with the capacitor 8C.
Capacitor C3 forming a resonant circuit for f3 and f4
-C4 shows another embodiment of the invention.

Regarding the operation, each loop coil 1. of the first loop coil group 1 is controlled by the drive-side scanning circuit 5. When scanning, each loop coil h has the above-mentioned 5 output from the frequency multiplexer 9.
one frequency f. It is driven by the -f4 signal. When none of the four function selection switches S and -S4 of the coordinate indicator 8 are pressed, the resonant circuit formed by the coordinate indicator coil 8L and the capacitor 8C resonates with the original signal frequency fo of the oscillator 3. As a result, only the coordinate information of the coordinate indicator 8 can be obtained, just as in the previous embodiment.

On the other hand, if any function selection switch, for example switch S, is closed, the resonant circuit consisting of the coordinate indicating coil 8L of the coordinate indicating device 8, and the capacitors 8C and C8 only responds to the frequency f. Since it resonates, the position of the coordinate indicator 8 can be detected from the output waveform appearing in the detection signal amplifier 7 due to the resonance, and the fact that resonance has occurred at the frequency f1 means that the output timing of this frequency is determined by the frequency multiplexer 9, for example. Since it can be known by importing it into a computer, it is possible to obtain information that the function selection switch S is pressed. In this way, each function selection switch 81 to S4
By selectively pressing the buttons, the functions represented by those switches can be instructed to the combination machine.

In this embodiment, only the capacitors C1 to C4 are switched by the function selection switches 81 to S4, but if necessary, other coils or capacitors may be connected to each resonance circuit selected by the function selection switches S and -S4. It goes without saying that it is possible to insert such as in an appropriate circuit configuration. Furthermore, methods for obtaining multiple frequencies are not limited to frequency multiplication or frequency division as described above, but can also be obtained using multiple oscillators, voltage controlled oscillators (VCO), etc. be.

〔Effect of the invention〕

As explained above, the electromagnetic induction digitizer of the present invention has a first loop coil group driven by an alternating current signal of a predetermined frequency on the digitizer plate surface, and a second loop coil subjected to the electromagnetic induction action of the first loop coil group. At the same time, the coordinate indicator is provided with a resonant circuit including a coordinate indicator fill and a capacitor and whose resonant frequency is the above-mentioned predetermined frequency, and when driving each coil of the first loop coil group near the coordinate indicator. Since the current position of the coordinate indicator is detected by utilizing the fact that the electromagnetic induction effect received by each loop coil of the second loop coil group changes due to the resonance of the resonant circuit, the simple and lightweight cordless coordinate indicator The indicator improves work efficiency and eliminates the hassle of battery replacement.

Furthermore, by driving the first loop coil group with multiplexed signals of a plurality of frequencies, and providing the coordinate detector with a resonant circuit selectable by a switch whose resonance frequency is each of these plural frequencies, the coordinates can be determined. Switch information on an indicator can be reliably input without malfunction.

[Brief explanation of the drawing]

Figure 1 (the left side is a block diagram of an embodiment of the electromagnetic induction type digitizer of this invention, Figure 1 (■) is an equivalent circuit diagram of the resonant circuit of the coordinate indicator, and Figure 2 (the left side is a block diagram of an embodiment of the electromagnetic induction type digitizer of this invention) A block diagram of another embodiment of the digitizer, Fig. 2 (c) is an equivalent circuit diagram of the resonant circuit of the coordinate indicator, and Fig. 3 (3)
is a waveform diagram showing an example of the output waveform of the coordinate indicator, Fig. 3 (
Figure 3 is a waveform diagram showing a waveform obtained by filtering high frequency components of the waveform, and Figure 4 is a schematic diagram showing the structure of an example of an electromagnetic induction digitizer according to the prior art.1... First loop coil group, 1...Loop coil, 2...Second loop coil group, 2
,...Loop coil, 3...Oscillator, 4...Drive amplifier, 5...Drive side scanning circuit, 6...Detection side scanning circuit, 7...Detection signal amplifier, 8...・Coordinate indicator, 8L...Coordinate indicator coil, 8
C, Cs = C2lC3-Ca...capacitor,
S+, Sz-S: 1- Sa...Function selection switch, 9...Frequency multiplexer.

Claims (2)

[Claims] (1) A first loop coil group consisting of a number of loop coils selectively driven by an AC signal of a predetermined frequency arranged at equal intervals on the digitizer plate surface, and an electromagnetic wave generated by each coil of the first loop coil group. The first loop coil group is made up of a large number of loop coils arranged at equal intervals on the surface of the digitizer plate so that the induction effect is approximately equal to each other, and the second loop coil group is electrically insulated from the second loop coil group. a coordinate indicator movable on the surface of the digitizer plate having a coordinate indicator coil disposed therein and a capacitor forming a resonant circuit for the predetermined frequency together with the coordinate indicator coil; When each coil of the first loop coil group is driven, the electromagnetic induction effect that each loop coil of the second loop coil group receives changes due to the resonance of the resonant circuit of the coordinate indicator, so that the current position of the coordinate indicator can be determined. An electromagnetic induction digitizer designed for detection. (2) The first loop coil group is provided with frequency multiplexing means for multiplexing and driving two or more predetermined frequencies, and each of these two or more predetermined frequencies is applied to the coordinate detector. 2. The electromagnetic induction digitizer according to claim 1, further comprising two or more resonant circuits selectable by a switch to set the resonant frequency.