JPH052448A - Coordinate detector - Google Patents

Abstract

PURPOSE:To detect the coordinates at a high speed by a coordinate detector which uses an electromagnetic induction feed means. CONSTITUTION:The exciting loops L01-Ln are arranged in the prescribed positional relation to the detection loops D01-Dn, and an exciting current is supplied to the loop L01 from an exciting frequency switching circuit 1. Thus the voltage is induced at the loop D01. The same operating is carried out to each loop by switching the selectors 2 and 3. The voltage of the loop including an indicated I is lower than that of the loop including no indicator in accordance wit the position of the indicator I in the relevant loop. A controller 7 computes the coordinates of the position of the indicator I based on these induced voltage. Thus the coordinate detecting speed is extremely improved since the feed and the detection are carried out at one time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate detector for detecting the coordinates of a position on a tablet designated by an indicator.

[0002]

2. Description of the Related Art A coordinate detector comprises a tablet in which a number of detection loops are wired for the X axis and the Y axis, respectively.
The tablet includes an indicator such as an electromagnetic pen or a cursor that indicates an arbitrary position on the tablet, and a detector that detects the coordinates of the position indicated by the indicator. The indicator has an oscillation coil inside, and a magnetic field is generated by supplying an exciting current to the oscillation coil from a cord connected to the detection unit, and the detection unit is guided to the detection loop by the generated magnetic field. Coordinate detection based on the voltage. In such a coordinate detector, the operator holds the indicator to indicate the desired position, but every time the indicator is operated on the tablet, the code also moves together with the indicator, so for the operator There is a drawback that the operation of the indicator is complicated and inconvenient to handle. To solve this drawback, coordinate detectors have been devised that do not require a cord to connect the indicator. This coordinate detector is provided with a battery and an oscillation circuit inside the indicator, and is configured to excite the oscillation coil using the battery as a power source. However, this requires maintenance of the battery because it requires replacement of the battery. However, the weight and volume of the indicator are not satisfactory. For this reason, an electromagnetic induction power feeding means for exciting an oscillation coil using a detection loop wired on a tablet has been proposed, for example, in Japanese Patent Publication No. 2-53805. The means is to provide a pickup coil in the indicator, generate an induced electromotive force in the pickup coil by exciting the detection loop of the tablet with alternating current, and excite the oscillation coil with this electromotive force to generate a magnetic field. is there.

[0003]

The coordinate detector having the above-mentioned electromagnetic induction power feeding means does not use a battery, and therefore has the advantage that the indicator does not require maintenance and its weight and volume can be reduced. However, this coordinate detector
The method of alternating-currently driving the detection loop of the axis whose position is to be detected to supply power to the indicator, and subsequently performing coordinate detection by the detection loop of the axis is repeated. Therefore, there is a problem in that it takes a long time to detect coordinates, and the number of position detections per unit time cannot be increased. An object of the present invention is to provide a coordinate detector which solves the above problems in the prior art, uses an electromagnetic induction power supply method, and can significantly reduce the detection time.

[0004]

In order to achieve the above object, the present invention comprises a large number of detection loops arranged in a predetermined axial direction at a predetermined pitch, and the detection loops are sequentially switched to change their voltage. In a coordinate detector that detects the position indicated by the indicator by detecting, one exciting loop is arranged for each of the one detecting loop, and the same position as the positional relationship between these detecting loops and the exciting loop. In relation to this, exciting loops are respectively arranged for the other detection loops, and exciting means for sequentially exciting these exciting loops is provided.

[0005]

When one exciting loop is excited by the exciting means, a voltage is electromagnetically induced in the detecting loop corresponding to this exciting loop, and this voltage is taken into the detecting means. This operation is sequentially executed for each combination of each excitation loop and detection loop. Since the voltage of the detection loop in which the indicator exists is lower than the voltage of the detection loop in which the indicator does not exist, the coordinates of the position of the indicator are detected based on the voltage of the detection loop (one or more). . Therefore, the power supply to the indicator and the coordinate detection are performed simultaneously, and the detection can be performed at high speed.

[0006]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a diagram showing a configuration of a wiring and a detection unit of a coordinate detector according to an embodiment of the present invention. D shown by the broken line in the figure
_{01 to} D _n are detection loops arranged on the tablet,
Each detection loop is sequentially arranged in a predetermined direction (for example, the X-axis direction). The pitch of the loops of the detection loops D _{01 to} D _n is the value p, and the deviation between the detection loops is the distance d. Further, L _{01 to} L _n indicated by solid lines in the figure are excitation loops, and the detection loop D ₀₁ to
Just below the D _n (or directly above), detection loop D ₀₁ to D _n and the same pitch p, are arranged in the same direction in the deviation of the same distance d. In each combination of the detection loop and the excitation loop, for example, in the combination of the detection loop D ₀₁ and the excitation loop L ₀₁ , the positional relationship between both loops is the same in any combination. I is an indicator that indicates an arbitrary position on the tablet. Although not shown, the above detection loops D _{01 to} D
_n , the same detection loop and excitation loop as the excitation loops L _{01 to} L _n are the detection loops D _{01 to} D _n and the excitation loop L.
They are arranged in a direction (Y axis) orthogonal to the arrangement direction of _{01 to} L _n .

An excitation frequency switching circuit 1 has a current source inside and switches the current from the current source to a predetermined frequency for output. 2 is each excitation loop L ₀₁ ~
A selector in which both ends of L _n are connected in order, and the exciting current from the exciting frequency switching circuit 1 is supplied to each exciting loop L _01.
Sequentially switched output to the ~L _n. Reference numeral 3 denotes a selector in which both ends of each of the detection loops D _{01 to} D _n are connected in order, and the voltages generated at the both ends are sequentially switched and input.
4 is an amplifier for amplifying the voltage input by the selector 3, 5
Is a center frequency variable band filter capable of varying the center frequency, 6 is an A / D converter, and 7 is a controller. The control device 7 includes an excitation frequency switching circuit 1, a frequency switching of the center frequency variable band filter 5, a selector 2,
The loop connection of No. 3 is switched, and the calculation of coordinates and various judgments are executed based on the voltage value input from the A / D converter 6.

Next, the operation of this embodiment will be described. The control device 7 switches the frequencies of the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5 to a predetermined frequency, and sets the selectors 2 and 3 to a predetermined excitation loop and a detection loop, for example, the excitation loop L ₀₁ and the detection loop D ₀₁ . Switch and connect to the terminal. When the excitation frequency switching circuit 1 outputs a switched current of a predetermined frequency, this current is supplied to the excitation loop L ₀₁ via the selector 2 and the excitation loop L ₀₁ is supplied.
₀₁ is excited. As a result, a voltage is induced in the detection loop D ₀₁ corresponding to the excitation loop L ₀₁ , this voltage is taken in by the selector 3, amplified by the amplifier 4, and the center frequency variable band filter 5 (the frequency of the excitation frequency switching circuit 1 is (Same frequency as above) and converted into a digital value by the A / D converter 6 and input to the controller 7. Such an operation is performed by sequentially switching the selectors 2 and 3 to change the combination of the excitation loop L ₀₂ and the detection loop D ₀₂ to the excitation loop L _n ,
It is executed for each combination up to the combination of detection loops D _n . The control unit 7 receives each detection loop D _01-
The coordinates of the position of the indicator I are calculated based on the voltage of D _n .

Here, it is assumed that the indicator I indicates the position shown in FIG. The voltage induced in the detection loop D ₀₂ in this case will be described with reference to FIG. FIG. 2 is a characteristic diagram of the voltage induced in each detection loop. In the figure, the horizontal axis shows the position on the coordinate axis (X axis), and the vertical axis shows the induced voltage. The position within the chain line is the loop region of the detection loop D ₀₂ , 0 is the starting position of this region, p is the ending position of this region, and the distance between both positions is equal to the pitch p. When the indicator I is in the loop area of the detection loop D ₀₂ , the voltage taken into the selector 33 increases as indicated by the solid line B in FIG. 2 depending on the position of the indicator I. When the indicator I is at the center position of the detection loop as shown in FIG. 1, the voltage taken in by the selector 3 is the minimum voltage V as shown in FIG.
Become _MIN . When the indicator I does not exist in the area, the induced voltage has a large constant value as shown by the broken line A. As described above, the voltage induced in the detection loop in which the indicator I is present decreases because the excitation energy generated in the excitation loop includes a resonance circuit including the pickup coil of the indicator I in addition to the detection loop (described later). This is because the excitation energy supplied to the detection loop is reduced. In the case shown in FIG. 1, the indicator I has detection loops D ₀₁ and D _02.
Are also present in the detection loop D ₀₁ , D
_The voltage induced in ₀₂ is also lower than the voltage of the detection loop in which the indicator I does not exist (greater than the voltage of the detection loop D ₀₂ )
Becomes The control device 7 calculates the coordinates of the position of the indicator I based on the detected values of the detection loops D ₀₁ , D ₀₂ , D ₀₃ among the input voltage values. In this case, the coordinates can be calculated based only on the detection voltage V _MIN of the detection loop D ₀₂ that has detected the lowest voltage, but the detection values of the detection loops D ₀₁ and D ₀₃ are also increased to improve the accuracy. To be adopted. When the deviation d between the distances of the respective detection loops is small, the indicator I is present over four or more detection loops. In such a case, a required detection centered on the detection loop that detects the lowest voltage is required. The detection voltage of the detection loop will be adopted. The above operation is the same for the detection in the Y-axis direction. With the above configuration and operation, power supply and coordinate detection are performed at the same time, and detection can be performed at high speed.

By the way, in general, the indicator I is the controller 7
There are provided switches for giving various commands to the operator, and the operator can obtain a desired result by selectively operating these switches. However, since the cord is not connected to the indicator I of this embodiment, it is impossible to give an instruction by the switch. In order to solve this, the excitation frequency switching circuit 1 and the center frequency variable band filter 5 are provided in this embodiment. For example, when the indicator I is provided with k switches, different frequencies of (k + 1) are set in the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5, and the switches operated by these set frequencies are set. Are discriminated against. This will be described with reference to FIGS. 3 and 4.

FIG. 3 is a circuit diagram of a resonance circuit provided inside the indicator I. As shown in FIG. In FIG. 3, L is a coil (pickup coil), C _{00 to} C _k are capacitors, and S _{01 to} S _k are switches provided in the indicator I. If the operator has not actuated the switch, the resonant circuit composed of a coil L and a capacitor C _00. The center frequency f ₀₀ of this resonance circuit is set in the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5. When the switch S ₀₁ is operated, the coil L and the capacitors C ₀₀ and C ₀₁ form a resonance circuit, and the center frequency f ₀₁ thereof is set in the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5. Similarly, for the switch S _k , a coil L and capacitors C ₀₀ and C _{k form} a resonance circuit, and its center frequency f _k is set in the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5.

Here, for example, it is assumed that the indicator I indicates the position shown in FIG. 1 with the switch S ₀₂ pressed.
On the other hand, the frequencies of the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5 are initially set to, for example, the frequency f ₀₀ . In this setting state, as described above, the exciting frequency switching circuit 1 outputs the exciting current of the frequency and the voltage of the detection loop D ₀₁ is input to the control device 7. Then
The control device leaves the selectors 2 and 3 as they are, switches the set frequencies of the excitation frequency switching circuit 1 and the center frequency variable bandpass filter 5 to the next frequency f ₀₁ , and inputs the voltage to the excitation loop L ₀₁ . The same operation is performed by sequentially switching the set frequency to the frequencies f _{02 to} f _k and setting. When the operation for each frequency f _{00 to} f _k ends,
The control device 7 switches the selectors 2 and 3 to the detection loop D ₀₂ and again detects the frequencies f _{00 to} f _k . Such an operation is also executed for each of the subsequent detection loops D _{03 to} D _n . FIG. 4 is a diagram showing each detection voltage of the detection loop D ₀₂ when the current of each set frequency is output to the excitation loop L ₀₂ . In the figure, the horizontal axis represents the position on the tablet and the vertical axis represents the voltage. Each waveform A ₀₀ ~
A _k indicates the voltage at each set frequency f _{00 to} f _k . As shown by the waveform A ₀₂ in the figure, the same voltage as that shown in FIG. 2 is detected only when the exciting current is set to the frequency f ₀₂ , and the voltage is not detected when the exciting current is set to other frequencies. . That is, the resonance circuit of the indicator I is configured to resonate at the frequency f ₀₂ (coil L and capacitors C ₀₀ and C ₀₂ ), and does not resonate at frequencies other than the frequency f ₀₂ and absorbs excitation energy. Because there are almost no. Since the voltage of the waveform A ₀₂ is generated at the set frequency f ₀₂ , the control device 7 determines that the switch S ₀₂ is activated and performs the process according to the command corresponding to this switch. When the switch is not pressed, or when another switch is pressed, the determination is performed by the same operation.

As described above, in this embodiment, the excitation loops are arranged so as to coincide with the detection loops, the excitation current is supplied to each excitation loop, and the induced voltage of the detection loop corresponding to the excitation loop is supplied. Since this is detected, it is possible to perform power supply and detection at the same time, and it is possible to perform high-speed detection. Further, since the indicator is provided with a resonance circuit according to the number of the switches and the exciting current is sequentially supplied at a frequency matching the center frequency of each resonance circuit,
The switch of the indicator can be discriminated.

In the description of the above embodiment, an example in which the excitation loop is arranged so as to coincide with and overlap with the detection loop has been described, but the present invention is not limited to this, and the excitation loop may slightly protrude from the detection loop. You can place it
Also, they can be arranged at an angle to each other or at 90 degrees. However, the positional relationship between the detection loop and the excitation loop must be the same for each combination. further,
The supply of the exciting current and the detection of the induced voltage are not limited to the order as in the above embodiment, the voltage detection of all detection loops is performed for one set frequency, and then the detection is performed again for the next set frequency. A method of detecting the voltage of all detection loops may be used. Further, if the indicator is not provided with a switch, it is natural that the frequency is set to one certain frequency.

As described above, according to the present invention, each excitation loop is arranged in a predetermined positional relationship in each detection loop, an excitation current is supplied to each excitation loop, and an induced voltage of the detection loop corresponding to the excitation loop is supplied. Since this is detected, it is possible to perform power supply and detection at the same time, and it is possible to perform high-speed detection.

[Brief description of drawings]

FIG. 1 is a diagram showing a wiring of a coordinate detector and a configuration of a detection unit according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a voltage induced in the detection loop shown in FIG.

FIG. 3 is a circuit diagram of a resonance circuit included in the indicator shown in FIG.

FIG. 4 is a waveform diagram of a voltage for each set frequency of the detection loop shown in FIG.

[Explanation of symbols]

1 Excitation frequency switching circuit 2, 3 Selector 5 Center frequency variable band filter 6 A / D converter 7 Control device D _{01 to} D _n Detection loop L _{01 to} L _n Excitation loop I Indicator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihisa Osaka             2100 Kamiimazumi, Ebina City, Kanagawa Prefecture             Within Kou Co., Ltd.

Claims (2)

[Claims] 1. Coordinate detection comprising a large number of detection loops laid out in a predetermined axial direction at a predetermined pitch, wherein each detection loop is sequentially switched to detect its voltage to detect the position indicated by the indicator. In this device, one excitation loop is arranged for each of the one detection loop, and excitation loops are arranged for the other detection loops in the same positional relationship as the positional relationship between these detection loops and the excitation loop. And a coordinate detector provided with an excitation means for sequentially exciting these excitation loops. 2. The indicator according to claim 1, wherein the indicator includes one resonance circuit having a different center frequency from the number of switches of the indicator, and the exciting means includes:
A coordinate detector comprising switching means for switching and outputting a current having the same frequency as the center frequency.