JP3134238B2 - Cordless digitizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless digitizer comprising a tablet and a position indicator wirelessly connected to the tablet, for detecting the position of a position indicator mounted on the tablet.

[0002]

2. Description of the Related Art Generally, a conventional digitizer comprises a tablet 1 having a plurality of coils arranged in X and Y directions and a position indicator 2, as shown in FIG. The drive circuit 4 for driving the drive 2 and the position indicator 2 are of a wired type connected by a cord 3. When the position indicator 2 is placed on the tablet 1 and the drive circuit 4 drives the position indicator 2, the LC resonance circuit including the coil and the capacitor provided in the position indicator 2 resonates. By detecting the voltage induced in the coil disposed on the tablet 1 by the resonance of the position indicator 2, the XY plane position of the position indicator 2 is detected.

In addition, among these types of digitizers, a so-called cordless digitizer in which the code 3 and the drive circuit 4 are omitted in recent years has been proposed. In such a cordless digitizer, for example, when detecting the position of the position indicator 2 by an electromagnetic induction method, the tablet 1
On the side, an oscillation coil group arranged in the X direction, a reception coil group arranged in the Y direction orthogonal to the transmission coil group, and an oscillator that supplies a current signal of a predetermined frequency to the oscillation coil group are provided. Are sequentially selected by the Y-axis scanner and applied to the oscillation coil group, and the induced voltage generated on the reception coil group side by electromagnetic coupling with the oscillation coil group when the position indicator is mounted on the tablet. The position of the position indicator is detected by detecting through scanning of the X-axis scanner.

[0004]

However, in the case of the first example of the prior art, since the position indicator 1 and the drive circuit 4 are of a wired type in which the cords 3 are connected, the operability is poor. there were. Further, in the case of cordless as in the second example, expensive scanners such as an X-axis scanner and a Y-axis scanner are required, and there is a disadvantage that the apparatus cannot be configured economically.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a position indicator that is electromagnetically coupled to a tablet and includes at least a coil and a capacitor. And a first drive coil disposed at regular intervals and in a zigzag manner, and having an interval equal to 1/2 of the interval between the first drive coils. A second driving coil disposed in a zigzag pattern; a driving circuit for driving the first and second driving coils by applying sine and cosine current signals, respectively; A first receiving coil group, which is disposed so as to be orthogonal to the direction in which the drive coils are disposed, and whose voltage is induced by the magnetic field of the position indicator; Calculate position in direction 1 Second perpendicular to Rutotomoni first direction
Means for calculating a partial position in the direction of the arrow and a second receiving coil group arranged in parallel with the first and second drive coils and detecting the entire position of the position indicator in the second direction on the tablet It is provided.

[0006]

When a sine wave signal and a cosine wave signal are applied to the first and second drive coils in the tablet, respectively, the position indicator placed on the tablet and in an electromagnetically coupled state with the tablet is driven to generate a magnetic field. The generated magnetic field is detected by the first receiving coil, and the position of the position indicator is calculated. Therefore, when detecting the position of the position indicator, an external circuit for driving the position indicator and a code for connecting the external circuit to the position indicator can be omitted. Further, when calculating the position of the position indicator in the first direction, the partial position in the second direction is calculated, and the entire position can be detected by the second receiving coil group. The need for a scanner is eliminated.

[0007]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a cordless digitizer according to the present invention. In the figure, a tablet 1 that performs position detection and the like of a position indicator 2 includes a first receiving coil group y1 that is disposed on a first grid plate in the X-axis direction.
To yn, drive coils x1 and x2 arranged at regular intervals in a zigzag manner in the Y-axis direction on the second grid plate, and second reception coils arranged in the Y-axis direction on the third grid plate Groups z1 to z3, drive circuits 11 and 12, phase shifter 13, sine wave oscillator (hereinafter, oscillator) 14, Y-axis scanner unit 15,
It comprises an amplifier 16 and a control circuit 17.

Here, the sine wave current signal from the oscillator 14 is always applied to the drive coil x1 via the phase shifter 13 and the drive circuit 11, and the drive coil x2 is also constantly applied with the sine wave current signal at 90 ° from the sine wave current signal. The drive circuit 12 applies a cosine wave current signal with a delayed phase. When the position indicator 2 is mounted on the drive coil to which the sine wave and cosine wave current signals are applied, a current flows through the coil in the position indicator 2 to generate a magnetic field. The control circuit 17 applies an induced voltage generated in the first receiving coil groups y1 to yn by the magnetic field generated by the position indicator 2 to the Y-axis scanner unit 15.
Is detected by scanning. Then, the position of the position indicator in the Y-axis direction and the position within a certain coil interval in the X-axis direction are calculated from the detected induced voltage value. In addition,
In order to calculate the entire position in the X-axis direction, the direction of the induced current generated in the second receiving coil groups z1 to z3 is detected and determined.

Next, FIG. 2 is a diagram showing a detailed configuration of the cordless digitizer, wherein (a) of FIG. 2 shows the configuration of the position indicator 2 and (b) to (d) of FIG. Each configuration is shown. FIG. 3 is a diagram showing an induced voltage waveform generated in the first receiving coil group, and FIG. 4 is a diagram showing the operation principle of the present digitizer. The details of the present invention will be described with reference to FIGS. Here, the position indicator 2 shown in FIG.
Is composed of a coil 21 and a capacitor 22, etc., and L is applied by applying a current signal to the drive coils x1 and x2.
The C-resonant circuit resonates to generate a magnetic field, and is therefore a cordless type which does not require a separate drive circuit 4 and a cord 3 for connecting the drive circuit 4 and the position indicator 2 as in the prior art. is there. Further, the coil diameter of the coil 21 is determined to be approximately L / 2 with respect to a coil interval L described later.

FIG. 2B shows the first side of the tablet.
The first receiving coil groups y1 to y1 formed on the grid plate
FIG. 6 is a diagram showing the arrangement of yn, and each of the receiving coils y1 to yn is arranged in parallel in the X-axis direction. Then, when a magnetic field is generated from the position indicator 2, an induced voltage is generated in a receiving coil disposed in the vicinity thereof, and the generated induced voltage is transmitted to the control circuit 17 via the Y-axis scanner unit 15. Next, FIG. 2C is a diagram showing the arrangement of the drive coils x1 and x2 formed on the second grid plate. Here, the drive coils x1 and x2 are both arranged in a zigzag manner at the same interval. For example, the drive coil x2 when the drive coil x2 is formed on the second grid plate by one reciprocation.
Let L be the interval in the X-axis direction of the drive coil x2
Are displaced from the drive coil x1 by L / 4. Then, a sine wave (sin ωt) is applied to the drive coil x1.
Is supplied to the drive coil x2 by a cosine wave (cos ω).
When the current signal of t) is applied, a voltage V as shown in Expression (1) is generated in the position indicator 2 placed on the tablet.

V = sin (ωt + 2πx / L) (1)

Therefore, the position indicator 2 is in a resonance state, and a magnetic field is generated from the coil 21. As a result, the first receiving coil group y1 disposed on the first grid plate
~ Yn produces an induced voltage as shown in FIG. The position of the position indicator 2 in the Y-axis direction is determined from the peak value of the induced voltage.

The voltage induced in the first receiving coil groups y1 to yn is generated in relation to the voltage V shown in the equation (1). Phase difference 2πx / L from wave (sinωt)
Is obtained, the position x of the position indicator 2 in the X-axis direction can be obtained. That is, as shown in FIG. 4A, the interval L between the drive coils x1 is known, and the position (partial position) x of the position indicator 2 within this interval is the phase difference among the detected induced voltages. If you just ask for it, it will be determined automatically.

However, the position x thus determined
Is a partial position within the arrangement interval of the drive coil,
It is not possible to determine where the position indicator 2 is located in the X-axis direction. Generally, as shown in FIG. 4B, when the position indicator 2 for generating a magnetic field exists in the area A and in the area B, the coil z0
The direction of the current flowing through is different. Here, when the position indicator 2 exists in the area A, the direction of the current generated in the coil z0 is “ON”, and when the position indicator 2 exists in the area B, the direction of the current generated in the coil z0 is “OFF”. When the intervals between the second receiving coils z1, z2, and z3 arranged in the axial direction are set to be twice, four times, and eight times as large as the intervals between the driving coils x1 and x2, FIG. 8) can be identified.

That is, when three receiving coils z1 to z3 are arranged in the Y-axis direction so as to be twice, four times and eight times the interval pitch between the driving coils x1 and x2, as shown in FIG. 2D. As described above, rough position information indicating where the position indicator 2 exists in the eight areas is transmitted to the control circuit 17. As a result, the position of the position indicator 2 is roughly determined in the control circuit 17, and the position indicator in the X-axis direction is determined based on the approximate position (overall position) and the partial position within the above-described drive coil arrangement interval. 2
The exact position of is required. In the present embodiment, eight regions are identified by the three second receiving coils z1 to z3 to determine the approximate position of the position indicator. However, the tablet surface is wide and a large number of drive coils are distributed. If it is desired to increase the number of area identifications, the number of second receiving coils is added, and the added second receiving coils are further increased by 16 times, 3
It is arranged so that it becomes twice,.

[0016]

As described above, according to the present invention, when a sine wave signal and a cosine wave signal are applied to the first and second drive coils in the tablet, respectively, the tablet is placed on the tablet and is in an electromagnetically coupled state with the tablet. Is driven to generate a magnetic field, and the position of the position indicator is calculated by detecting the voltage induced in the first receiving coil by the generated magnetic field. At the time of position detection, an external circuit for driving the position indicator and a code for connecting the external circuit to the position indicator can be omitted. Further, when calculating the position of the position indicator in the first direction, the partial position in the second direction is calculated, and the entire position in the second direction can be detected by the second receiving coil group. Therefore, an expensive scanner for detecting the direction position is not required, and the apparatus can be constructed economically.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a cordless digitizer according to the present invention.

FIG. 2 is a diagram showing a detailed configuration of each unit of the digitizer.

FIG. 3 is a waveform diagram of an induced voltage generated in a receiving coil of the digitizer.

FIG. 4 is a diagram for explaining a position detection state of a position indicator in the digitizer.

FIG. 5 is a block diagram of a conventional digitizer.

[Explanation of symbols]

 Reference Signs List 1 tablet 2 position indicator 11, 12 drive circuit 13 phaser 14 sine wave oscillator 15 Y axis scanner unit 16 amplifier 17 control circuit 21 coil 22 capacitor x1, x2 drive coil y1 to yn first reception coil z1 to z3 second Receive coil

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 3/03

Claims (1)

(57) [Claims] 1. A cordless digitizer, comprising a tablet and a position indicator electromagnetically coupled to the tablet, for detecting a position indicated by the position indicator mounted on the tablet, comprising: A first drive coil disposed in the first drive coil, a second drive coil disposed in an equidistant and zigzag manner with a shift of 間隔 from the distance between the first drive coils, and the first drive coil; A driving circuit that applies and drives sine and cosine wave current signals to the second driving coil, respectively;
The position indicator, which includes at least a coil and a capacitor and generates a magnetic field by driving the first and second drive coils, is disposed to be orthogonal to the direction in which the first and second drive coils are disposed. A first receiving coil group in which a voltage is induced by the magnetic field of the position indicator, and a first voltage of the position indicator based on an induced voltage generated in the first receiving coil group.
Means for calculating a position in a second direction and calculating a partial position in a second direction orthogonal to the first direction;
A second receiving coil group disposed in parallel with a second drive coil and detecting an entire position of the position indicator in a second direction.