JPS63108425A - Position detector - Google Patents

Abstract

PURPOSE:To attain simultaneous use of plural indicators by sending a radio wave from each coil of a position detection section, receiving a generated radio wave by a tuning circuit of the position indicator so as to detect its designated position thereby offering excellent operability and high accuracy. CONSTITUTION:A loop coil 11-1 of a position detection section 1 is selected at first and a transmission circuit 6 is connected, then a radio wave of a prescribed frequency is generated. The radio wave excites the coil in the position indicators 4, 5 and an induced voltage of a prescribed frequency or the n-th order harmonic is generated from tuning circuits 41, 51. When the coil 11-1 is switched to a reception circuit 7, the radio wave is lost. The radio wave from the indicators 4, 5 is received by the circuit 7, the coil 11 is excited in opposite polarity, the induced voltage having the same frequency as the received radio wave is combined and generated. The transmission/reception of the radio wave is executed sequentially by switching all loop coils, but the mode small the distance with each indicator, the more induced voltage is larger and at a maximum while the indicator is placed. Each induced voltage is detected by the circuit 3 by each frequency and the coordinate of the designated part of each indicator is obtained by a processing unit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position detection device that can use a plurality of cordless position indicators simultaneously.

(Prior Art) As a conventional position detection device, a pulse current is applied to a drive coil provided at one end of a magnetostrictive transmission medium or a tip of a position indicator, and magnetostrictive vibration waves are generated in the magnetostrictive transmission medium. , a processing device or the like measures the time until an induced voltage based on the magnetostrictive oscillation waves is detected in a detection coil provided at the tip of the position indicator or one end of the magnetostrictive transmission medium, and calculates the designated position of the position indicator from this. There was something I did.

In addition, as another conventional position detection device, a plurality of drive lines and detection lines are arranged perpendicularly to each other, and current is sequentially applied to the drive lines and detection lines are sequentially selected to detect induced voltage. There is a device in which a position specified by a position indicator made of a magnetic material such as ferrite is detected from the position of a detection line in which a large induced voltage is induced.

(Problem to be solved by the invention) Although the former device has relatively good position detection accuracy, it requires a code between the position indicator and the processing device to send and receive timing signals, etc. Handling is severely restricted, and the position indicator must be held perpendicular to the magnetostrictive transmission medium and used in close proximity.

In addition, in the latter device, the position indicator can be made cordless, but the resolution of the coordinate position is determined by the spacing between the lines, and if the spacing between the lines is made small to increase the resolution, the S/N ratio and stability will deteriorate. Therefore, it is difficult to increase the resolution, and it is also difficult to detect the position directly above the intersection of the drive line and the detection line, and the position indicator must be brought very close to the line. Further, in any of the above-mentioned devices, there is a problem in that it is not possible to detect the specified position by using two or more position indicators at the same time.

The present invention has improved these conventional problems, and has good operability because the position indicator is not connected anywhere, can use multiple position indicators simultaneously, and has highly accurate position detection. The purpose is to provide a device that can.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a position detecting section including a large number of loop coils arranged in parallel in the position detection direction, and a position detecting section including a plurality of loop coils arranged in parallel in the position detection direction; a transmission circuit that drives the selected one loop coil with an alternating current signal of a predetermined frequency, and a coil and a capacitor,
．． 3゜...) among a plurality of position indicators each having a tuning circuit whose tuning frequency is the frequency of the harmonic, and the voltage generated in the selected one loop coil, the predetermined frequency or a receiving circuit that detects an induced voltage having approximately the same frequency as the frequency of the n-th harmonic for each of the predetermined frequency and the frequency of the n-th harmonic; and a receiving circuit that connects the selected one loop coil to the transmitting circuit and the receiving circuit. A first invention is constituted by a connection switching circuit that is alternately connected to the circuit, and a processing device that calculates designated positions of a plurality of position indicators from each of the induced voltages generated in each loop coil, and a plurality of loop coils. are arranged in parallel in the X and Y directions, respectively, and one loop coil in the X and Y directions is sequentially selected from the plurality of loop coils in the X and Y directions. a transmission circuit that drives one of the selected loop coils in the X and Y directions with an alternating current signal of a predetermined frequency, and a coil and a capacitor; A plurality of position indicators each having a tuning circuit whose tuning frequency is the frequency of the nth (=2.3...)th harmonic, and one loop in the selected X direction and Y direction. a receiving circuit that detects an induced voltage of approximately the same frequency as the frequency of the predetermined frequency or its n-th harmonic among the voltages generated in the coil, for each frequency of the predetermined frequency and its n-th harmonic; an X-direction and Y-direction connection switching circuit that alternately connects one loop coil in the X-direction and Y-direction to the transmitting circuit and the receiving circuit; and each of the inductions generated in each of the X-direction and Y-direction loop coils. The second invention includes a processing device that calculates designated positions of a plurality of position indicators in the X direction and the Y direction, respectively, based on the voltage.

(Function) According to the first invention, one of the plurality of loop coils is selected by the selection circuit, the transmission circuit is connected to it by the connection switching circuit, and an alternating current signal of a predetermined frequency is passed. Then, radio waves are generated from the loop coil.

The radio wave excites the coils in the plurality of position indicators that designate positions on the position detection section, and transmits the AC signal or its n (=2.3...)th harmonic to each tuned circuit. Generates induced voltage synchronized with waves. Thereafter, when a receiving circuit is connected to the selected one loop coil by the connection switching circuit and the AC signal is disconnected, the radio wave disappears. On the other hand, a current having the same frequency as the frequency of the AC signal applied to the one loop coil or the frequency of its nth harmonic flows in the tuned circuit of each position indicator based on the generated voltage, and this current is Radio waves are generated from the coils in each tuned circuit. Since each radio wave reversely excites the first loop coil connected to the receiving circuit, an induced voltage having the same frequency as the frequency of the AC signal and its n-th harmonic is synthesized in the first loop coil. occurs. The transmission and reception of the radio waves is repeated sequentially by switching the loop coils, and is performed by resonance between the loop coil and the coil of each position indicator, so the shorter the distance between the loop coil and the coil of each position indicator, the more The voltage value of the induced voltage increases. Therefore, the induced voltage generated in the loop coil closest to the position where the position indicator is placed (specified position) is the maximum value, and the induced voltage that gradually decreases as it moves away from the specified position is applied to each loop for each position indicator. Occurs in the coil. The voltage value of each induced voltage is detected by a receiving circuit at each predetermined frequency and its n-th harmonic frequency, and is further processed by a processing device to determine the position where the voltage value is the maximum value, that is, the position of each position indicator. The coordinate values of each specified position are determined.

Note that even if each position indicator is moved along the direction perpendicular to the position detection direction, the distance between each loop coil and each position indicator does not change, so the same coordinate values can be obtained.

Further, according to the second invention, in the X and Y directions,
The induced voltage based on the resonance between the loop coil and the coil of each position indicator is determined, and from this the X of each position indicator is determined.
Then, the coordinate values of the so-called two-dimensional specified position in the Y direction are determined.

(Embodiment) FIG. 1 shows a first embodiment of the position detection device of the present invention, in which 1 is a position detection section, 2 is a selection circuit, 3 is a connection switching circuit, and 4.5 is a position detection section. 6 is a transmitting circuit, 7 is a receiving circuit, and 8 is a processing device.

The position detection unit 1 includes a plurality of loop coils 11-1, 11-2, and 48 loop coils, for example, having conductors parallel to each other.・・・・・・
. . 11-48 are arranged in parallel in the direction of arrow A (hereinafter referred to as position detection direction) in the figure. Further, the loop coils 11-1 to 11-48 are arranged parallel to each other and overlapping each other. Although each of the loop coils 11-1 to 11-48 is configured with one turn here, it may be configured with multiple turns if necessary.

As the position detection unit 1, a plurality of loop coils formed by connecting a large number of parallel conductors formed by etching a well-known printed circuit board with jumper wires or the like may be used. Can be done.

The selection circuit 2 includes the plurality of loop coils 11-1 to 11.
One end of the loop coils 11-1 to 11-48 is connected to one terminal group 21, and the other end is connected to another terminal group 22, respectively. It is connected. The selection contact 23 corresponding to the terminal group 21 and the selection contact 24 corresponding to the terminal group 22 are interlocked with each other, operate based on information from the processing device 8, and select one loop coil.

The selection circuit 2 can be realized by combining a large number of well-known multiplexers.

The connection switching circuit 3 alternately connects one loop coil selected by the selection circuit 2 to the transmission circuit 6 and the reception circuit 7, and connects the selection contact 23 of the selection circuit 2 to the transmission circuit 6 and the reception circuit 7.
and 24 are connected to selection contacts 31 and 32, respectively. Furthermore, the two output terminals of the transmitting circuit 6 are connected to the terminals 33.35, and the two input terminals of the receiving circuit 7 are connected to the terminals 34.36. The terminal 33
Selection contact 31 corresponding to ゜34, and terminal 35゜36
The selection contacts 32 corresponding to the above are connected to each other and operate based on a transmission/reception switching signal, which will be described later, to switch between transmission and reception.

Note that the connection switching circuit 3 is also realized by a well-known multiplexer.

The position indicator (hereinafter referred to as an input pen) 4 and the position indicator (hereinafter referred to as a cursor) 5 incorporate tuning circuits 41 and 51, respectively, including a coil and a capacitor.

FIG. 2 shows the detailed structure of the input pen 4, in which a core 43 of a ballpoint pen or the like is inserted into a pen shaft 42 made of a non-metallic material such as synthetic resin from near its tip. A ferrite core 44 with a through hole that can be movably accommodated, a coil spring 45, and a switch 411. Coil 412 .wound around ferrite core 44 . capacitor 41
A tuning circuit 41 consisting of components 3 and 414 is integrated and built in, and a cap 46 is attached to the rear end.

As shown in FIG. 4, the coil 412 and capacitor 413 are connected in parallel with each other to form a well-known parallel resonant circuit, and the values of the coil 412 and capacitor 413 correspond to the frequency of the AC signal, which will be described later. At fO, the voltage and current phases are set to a value that resonates (synchronizes) in the same phase. In addition, the capacitor 414 is connected to the switch 4
11 to both ends of the coil 412 and the capacitor 413, and when the switch 411 is turned on, it has the effect of delaying the phase of the current in the parallel resonant circuit by a predetermined angle, for example, 90 degrees. Note that the switch 41
1, by pressing the tip of the core 43 against the input surface (not shown) of the position detection unit 1, the core 43 is connected to the pen shaft 42.
When pushed in, the rear end presses the coil spring 45 to turn it on.

FIG. 3 shows the detailed structure of the cursor 5. One end of the casing 52 made of non-metallic material such as synthetic resin has "
A transparent cylindrical body 53 made of plastic or the like is provided with a "+" indicator, and a switch 511 is provided on the side surface near the center. Further, a coil 512 is provided around the cylindrical body 53 so as to surround it, and furthermore, capacitors 513 and 514 are built in.

Although the coil 512 is shown as a two-turn coil in the drawing, it actually consists of several hundred turns. The switch 511. Coil 512. capacitor 5
13 and 514 constitute a tuning circuit 51.

The coil 512 and capacitor 513 are connected in parallel with each other to form a well-known parallel resonant circuit, as shown in FIG. n (=2
．． 3. . In addition, the capacitor 514 is connected to the switch 511
It is connected to both ends of the coil 512 and the capacitor 513 via the switch 511, and when the switch 511 is turned on, it acts to delay the phase of the current in the parallel resonant circuit described above by a predetermined angle, for example, 90 degrees.

FIG. 4 shows details of the tuning circuit 41.5L transmitting circuit 6 and receiving circuit 7 as well as the overall configuration of the device. In the figure, 601 is a waveform shaping circuit, 602 is a multiplier, and 603 is a waveform shaping circuit.
, 604 is a phase shifter, and 605 is a drive circuit, which constitute the transmitting circuit 6. Further, 701 is an amplifier, 702
, 703 is a bandpass filter (BPF) , 704 , 7
05, 706, 707 are phase detectors (PSD)
, 708 , 709 , 710 , 711 are low pass filters (LPF) , 712 , 713 , 714 ,
715 is an analog-to-digital converter (AD converter), which constitutes the receiving circuit 7.

The processing device 8 is composed of a well-known microprocessor, etc., and generates an alternating current signal and a transmission/reception switching signal, controls switching of each loop coil based on the output of the receiving circuit 7, and calculates coordinate values of a designated position.

Next, the operation will be explained. First, the position detection section 1 and the input pen 4. The manner in which radio waves are transmitted and received between the cursor 5 and the signals obtained at this time will be explained with reference to FIG.

The processing device 8 generates an alternating current signal, for example, a rectangular wave signal A, with a frequency fO, for example, 500 kHz, based on a clock from an oscillator (not shown), and also generates an alternating current signal, for example, a rectangular wave signal A, with a frequency of 15.625 kHz.
Generates a kHz transmission/reception switching signal B.

The rectangular wave signal Δ is sent to a waveform shaping circuit 601 where the waveform is shaped, and further sent to a multiplier 602 and a phase shifter 603. The multiplier 602 increases the frequency of the rectangular wave signal A by nl
Here, a rectangular wave signal C multiplied by three times 3fO is created and sent to the phase shifter 604.

The phase shifter 602 changes the phase of the rectangular wave signal A as it is (O
o) and signal 1 (not shown) delayed by 90 degrees, and send these to phase detectors 704 and 705, respectively.The phase shifter 603 changes the phase of the rectangular wave signal C. Signal left as is (0°) and 90°
Delayed signals (not shown) are created and sent to phase detectors 706 and 707, respectively.

On the other hand, the rectangular wave signal A is converted into a balanced signal by the drive circuit 605 and sent to the connection switching circuit 3. However, since the connection switching circuit 3 is switched and controlled by the signal B, the signal is selected by the connection switching circuit 3. The signal output to circuit 2 is
This is a signal that outputs or does not output a 500kHz pulse signal every 32μsec.

The signal is sent to one loop coil, for example 11-1, of the position detecting section 1 via the selection circuit 2, and at this time, the loop coil 11-1 generates a radio wave based on the signal.

At this time, if the input pen 4 is held in a substantially upright state near the loop coil 11-1 of the position detection section 1, the radio wave excites the coil 412 of the input pen 4, and its tuning circuit 41
An induced voltage E synchronized with the signal is generated.

By the way, since the radio waves compete based on the rectangular wave signal A, the fundamental frequency of the rectangular wave signal A, that is, f
Along with the O component, twice that amount.

It contains a harmonic component having a frequency of three times... Therefore, the radio wave generated from the loop coil 11-1 based on the signal excites the coil 512 of the cursor 5 placed at another position on the position detection unit 1, and the signal is transmitted to the tuning circuit 51. It generates an induced voltage F with a frequency three times that of the current.

Thereafter, when the loop coil 11-1 is switched to the receiving circuit 7 side as the signal enters a no-signal period, that is, the receiving period, the radio waves from the loop coil 11-1 disappear immediately, but the input bend 4 Since there is no circuit change in the tuning circuit 41 of the cursor 5 and the tuning circuit 51 of the cursor 5, the induced voltages E and F gradually attenuate.

On the other hand, based on the induced voltages E and F, the tuning circuit 41
The current flowing through coils 412 and 512
Each transmits more radio waves.

The radio waves are transmitted to the loop coil 11-1 connected to the receiving circuit 7.
In order to excite the loop coil 11-1 in the opposite direction, an induced voltage G is generated in the loop coil 11-1, which is a combination of the induced voltage caused by the radio waves from the coil 412 and the induced voltage caused by the radio waves from the coil 512.

Since the connection switching circuit 3 is switched by the transmission/reception switching signal B, the loop coil 1 is switched only during the transmission stop period.
Take in the induced voltage G from 1-1. The induced voltage G is amplified by an amplifier 701 and further passed through a bandpass filter 702.
and sent to 103.

Since the bandpass filter 702 is a filter having a passband centered at the frequency fO, only the voltage component induced by the tuning circuit 41 in the signal G appears in its output H, and similarly, the bandpass filter 103 receives a rectangular wave signal. @C frequency,
That is, since the filter has a pass band centered at 3fO, only the voltage component induced by the tuning circuit 51 in the signal G appears in its output I.

The signal H is input to phase detectors 704 and 705, respectively, and the signal I is input to phase detectors 706 and 70.
7 respectively.

The rectangular wave signal A is input to the phase detector 704 as a detection signal, and at this time, if the phase of the signal H matches the phase of the rectangular wave signal A, the signal H has just been inverted to the positive side. Outputs signal J. The signal J is converted into a flat signal K with a voltage of 2 by a low-pass filter 708 whose circular frequency is sufficiently low.

In addition, the phase detector 105 has the phase of the rectangular wave signal @A at 90°.
°A delayed signal A- (not shown) is input as a detection signal, and at this time, if the phase of signal H matches the phase of rectangular wave signal A', signal H is shifted to the positive side as before. Outputs the inverted signal. The signal is converted into a flat signal by a low-pass filter 709 similar to the above.

On the other hand, the rectangular wave signal C is input as a detection signal to the phase detection 3706. At this time, if the phase of the signal I matches the phase of the rectangular wave signal C, the signal Outputs an inverted signal. The signal is converted into a flat signal M of voltage VH by a low-pass filter 110 whose cut-off frequency is sufficiently low.

The phase detector 705 also detects the phase of the rectangular wave signal C by 90°.
°A delayed signal C' (not shown) is input as a detection signal, and at this time, if the phase of signal I matches the phase of rectangular wave signal C', the signal i is shifted to the positive side as before. Outputs the inverted signal. The signal is converted into a flat signal by a low-pass filter 111 similar to that described above.

Here, when the switches 411 and 511 are off at the input ben 4 and the cursor 5, the phases of the voltage and current at the resonance frequencies of the tuned circuits 41 and 51 match, respectively, as described above, and the reception The phases of the signals H and I and the rectangular wave signals A and C also match, respectively. Therefore, at this time, low-pass filters 708 and 7
A voltage appears only at the output of 10 and no voltage appears at the output of low pass filters 109 and 711.

In addition, when the switch 411 is turned on in the input vent 4, the phase of the current at the resonant frequency of the tuned circuit 41 lags the phase of the voltage by 90' as described above, and the received signal H The phase is also delayed by 90° with respect to the phase of the rectangular wave signal A. Therefore, at this time, a voltage appears only at the output of the low-pass filter 709 (note that if the phase delay at this time is less than 90°,
At both the outputs of the low-pass filters 708 and 709, a voltage value corresponding to the phase lag mother will appear.

).

Similarly, when the switch 511 is turned on at the cursor 5, the phase of the current at the resonant frequency of the tuned circuit 51 will be delayed by 90 degrees with respect to the phase of the voltage, as described above, and the phase of the received signal is delayed by 90'' with respect to the phase of the rectangular wave signal C. Therefore, at this time, a voltage appears only at the output of the low-pass filter 711 (note that even if the phase delay at this time is less than 90', Ba,
At both the outputs of the low-pass filters 10 and 711, voltage values corresponding to the phase lag will appear.

).

The outputs of the low-pass filters 708 to 711 are respectively AD
The signals are converted into digital values by converters 712 to 715 and sent to the processing device 8. The processing device 8 calculates the output values of the AD converters 712 and 713 and the output values of the AD converters 714 and 715 using the following formula (1).
, performs the arithmetic processing shown in (2).

VR= (VP +VQ 2)”2 −・−(1)
V −tan (VQ /VP ) −=(
2) θ Here, VP HaAO converter 712 <Also Huff 1
4) output value of VQ ha AD converter 713 (
1, t715). Further, the voltage VR indicates a value proportional to the distance between the input vent 4 (or cursor 5) and the loop coil 11-1, and the voltage Indicates a value proportional to the phase difference between voltage and current.

The value of the voltage VR changes when the loop coil 11-1 that transmits and receives radio waves to and from the input bevel 4 (or cursor 5) is switched, and from this point on, the position of the input ben 4 (or cursor 5) changes as will be described later. Detected.

Since the value of the voltage ■θ changes only by turning on and off the switch 411 (or 511), by comparing the voltage ■ with a predetermined threshold voltage, the switch 411
(or 511) is identified as on or off.

Next, the state of position detection in the apparatus of the present invention will be explained according to FIGS. 6 to 8.

First, when the entire device is powered on and enters the measurement start state, the processing device 8
~11-48, information for selecting the first loop coil 11-1 is sent to the selection circuit 2, and the loop coil 11-
1 to the connection switching circuit 3. The connection switching circuit 3 switches the loop coil 11-1 based on the transmission/reception switching signal B mentioned above.
is controlled to be alternately switched to the transmitting circuit 6 and the receiving circuit 7.

At this time, the transmitting circuit 6 transmits 16 pulse signals of 500kl-1z as shown in FIG. 6(a) during a transmission period of 32 μSeC (in FIG. ) is shown in the loop coil 11-
Send to 1. The switching between transmission and reception is repeated seven times for one loop coil, here 11-1, as shown in FIG. 6(b).

These seven transmission and reception repetition periods correspond to one loop coil selection period (448 μsec).

At the output of the phase detectors 704 to 707 of the receiving circuit 7, an induced voltage is obtained for one loop coil every seven reception periods, and as described above, this induced voltage is passed through the low pass filters 708 to 711. and the AD converter 71
2 to 715, it is converted into a digital value and sent to the processing device 8. At this time, AD converters 712, 713
The output value is converted into a detected voltage, for example, VRI, which is proportional to the distance between the input vent 4 and the loop coil 11-1 through the arithmetic processing of equation (1), and is temporarily stored.

At this time, at the same time, the output value of the AD converters 714 and 715 is converted into a voltage proportional to the distance between the cursor 5 and the loop coil 11-1 through the arithmetic processing of equation (1) above. I don't remember it at the moment.

Next, the processing device 8 sends information for selecting the loop coil 11-2 to the selection circuit 2, connects the loop coil 11-2 to the connection switching circuit 3, and connects the input vent 4 and the loop coil 11-2.
Detection voltage VR2 proportional to the distance from Detection voltages VRI to VR48 (however, only a part of them are shown in analog representation in FIG. 6(c)) are stored for each loop coil in proportion to the distance from the input vent 4.

The actual detected voltage is obtained only from several loop coils before and after the position e (XD ) where the input pen 4 is placed as the center, as shown in FIG.

When the voltage value of the stored detection voltage is above a certain detection level, the processing device 8 calculates a coordinate value representing the position of the input pen 4 from these voltage values as described later, and stores this in a memory (not shown). Transfer to the department.

Next, the processing device 8 generates a cursor 5 for each loop coil obtained by subjecting the output values of the AD converters 714 and 715 to the arithmetic processing of the above equation (1) when the selection circuit 2 is switched in the same manner as described above. The detected voltage proportional to the distance is temporarily stored, the coordinate value representing the position of the cursor 5 is calculated, and this is transferred to the storage section.

When the first position detection is completed in this way, the processing device 8 performs the second and subsequent position detection as shown in FIG.
Centering around the loop coil where the maximum detection voltage was obtained,
Information for selecting only a certain number of loop coils before and after, for example, 10, is sent to the selection circuit 2, the output value is obtained in the same manner as described above, and the position is detected with respect to the input bend 4 and the cursor 5, and the obtained coordinates are The value is transferred to the storage section and the value is updated.

In Fig. 8, the level check means checking whether the maximum value of the detected voltage has reached the detection level and which loop coil has the maximum detected voltage, and checking the detection level. If the coordinate calculation has not been reached, the coordinate calculation is stopped, and the center of the loop coil to be selected in the next detection operation is set.

On the other hand, the processing device 8 outputs the detected voltages VR1 to VR48 for the input pin 4 (or the cursor 5) as well as the tuning circuit 41 of the input pin 4 (or the tuning circuit 51 of the cursor 5).
Detection voltage proportional to the phase difference between voltage and current at ),
is calculated by the processing of equation (2) above, and the detected voltage V,
is constantly compared with a predetermined threshold voltage. Therefore, at this time, when the switch 411 of the input pen 4 (or the switch 511 of the cursor 5) is turned on, the processing device 8 detects this from the comparison result, and sets the coordinate values at this point as the coordinate values of the specified position. The data is sent to another computer, etc. (not shown).

One calculation method for determining the coordinate value xp is to approximate the waveform near the maximum value of the detected voltages VRI to VR48 by an appropriate function, and then determine the coordinates of the maximum value of the function.

For example, in FIG. 6(C), the maximum detection voltage VR3
, and the detection voltages VR2 and VH2 on both sides thereof can be approximated by a quadratic function, it can be calculated as follows (
However, the coordinate values of the center positions of each loop coil 11-1 to 11-48 are set to x1 to x48, and the interval therebetween is set to ΔX.

). First, from each voltage and coordinate value, VH2-a (x2-xp)2+b ------
・(3) VH3-a(x3-xp) +b −
Old-(4)VH2-a(x4-xp)2+b-・
・-(5). Here, a and b are constants (a<O).

Also, X3-X2-ΔX...
(6) x4-x2-2 ΔX...
...(1) j (6), (7) equations (4),
Substituting it into equation (5) and rearranging it, we get Xp-x2+Δx/2 ((3VR2-4VR3+VR
4)/ (VH2-2VR3+VR4))...
(8) becomes.

Therefore, from each detection voltage (old to VR48), extract the maximum detection voltage obtained during the level check and the detection voltages before and after it, and extract these and the loop coil from which the maximum detection voltage was obtained. The coordinate value xp of the specified position of the input pen 4 can be calculated by performing the calculation equivalent to the above-mentioned equation (8) from the coordinate value (known) of the previous loop coil, and in the same way, the coordinate value xp of the specified position of the input pen 4 can be calculated. You can calculate the coordinates of a specified position.

In addition, as mentioned above, the detection voltage for the input vent 4 is A
The detection voltage for the cursor is obtained from the D converters 712 and 113, and the detection voltage for the cursor is obtained from the AD converters 714 and 715.
Therefore, in addition to the level check, when the input pen 4 or the cursor 5 approaches the position detectable range of the position detection unit 1, it is possible to determine which of the input pen 4 or the cursor 5 approached as the input pen 4 or the cursor 5 approached. can be detected and displayed on a display (not shown).

In addition, by attaching a microphone or the like to the position detection unit 1 and providing the processing device 8 with a voice recognition function,
Various commands can be given by voice, and the processing device 8 can also be provided with a character recognition function and used as a tablet for inputting handwritten characters.

Further, in the embodiment, the tuning frequency f.

and a tuned circuit with a phase difference of 0° between voltage and current, a tuned circuit with a tuned frequency fO and a phase difference of 90'', a tuned circuit with a tuned frequency of 3fO
and a tuned circuit with a phase difference of 0° and a tuning frequency of 3fO
Position indicators each having a tuning circuit with a phase difference of 90° are prepared, and in the processing device 8, the AD converter 7
If the arithmetic processing of equation (8) is performed for each output value from 12 to 715, the positions of the four position indicators can be detected simultaneously without changing the configuration of the transmitting circuit 7 or receiving circuit 8. You can also do that.

Further, the number of loop coils and the arrangement thereof in the embodiments are merely examples, and it goes without saying that the present invention is not limited thereto.

FIG. 9 shows a second embodiment of the present invention, in which an example is shown in which position detection is performed in the X direction and the Y direction. That is, in the figure, reference numeral 1a denotes a position detecting section in the X direction and the Y direction, and two sets of the position detecting sections 1 in the first embodiment are stacked so that their loop coils are orthogonal to each other.

Also, 2a.

2b is a selection circuit for X direction and Y direction, 3a and 3b
605a and 605b are X-direction and Y-direction connection switching circuits, 605a and 605b are X-direction and direction drive circuits, and 701a and 701b are X-direction and X-direction amplifiers, which are the selection circuit 2 and the connection switching circuit 3 in the first embodiment, respectively. , drive circuit 605, and amplifier 701.

Further, 606 is an XY switching circuit which applies the AC signal from the phase shifter 603 to only either one of the drive circuits 605a or 605b to select the detection direction. A processing device 8a is similar to the processing device 8, except that position detection in the X direction and the Y direction is performed alternately. In addition, processing bag ff18
FIG. 10 shows the timing of the second and subsequent coordinate detection operations in a. As described above, according to this embodiment, two directions in the X direction and the Y direction for the input pen 4 and the cursor 5 are provided.
Direction position (coordinates) can be easily detected. Note that the other configurations and operations are the same as those of the first embodiment.

(Effects of the Invention) As explained above, according to the present invention, a predetermined frequency or its n(=2, 3, . . .
...) Radio waves are transmitted to multiple position indicators, each of which has a tuned circuit whose tuning frequency is the harmonic frequency, and a loop coil receives the radio waves sent in the opposite direction from each tuned circuit. The induced voltage generated at this time is detected for each frequency, and this is performed for all of the many loop coils, and the specified position of each position indicator is detected from the many obtained induced voltages. Since each position indicator can be detected and multiple coordinate values can be input at the same time, for example, when inputting a figure by setting up a selection area for various commands around the coordinate input range, it is possible to input a figure with one position indicator. While inputting the shape of the line, you can specify the scale and color of the line segment using other position indicators. There is no need to move the device, making it possible to create a device with good operability. In addition, it is only necessary to provide a tuning circuit whose main elements are a coil and a capacitor on the position indicator side.
This eliminates the need for cords and heavy parts such as batteries and magnets, which improves operability.Also, since the position detection unit does not require special parts, it can be made larger.
The present invention can be applied to electronic whiteboards, etc., and position detection accuracy can be improved by increasing the accuracy of calculation processing for the plurality of induced voltages obtained. Further, if the position detection section is provided in the X direction and the Y direction, there are advantages such as position detection in two directions, the X direction and the Y direction.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the position detection device of the present invention, FIG. 2 is a diagram showing a specific configuration of an input pen, and FIG.
Figure 4 shows the detailed configuration of the cursor, Figure 4 shows the detailed configuration of the tuning circuit, transmitter circuit, and receiver circuit, Figure 5 shows the waveforms of each part in Figure 4, and Figure 6 (a) shows the detailed configuration of the cursor. )(b)(c
) is a timing diagram showing the basic detection operation in the first embodiment, FIG. 7 is a diagram showing the detection voltage obtained from each loop coil during the first detection operation, and FIG. 8 is a diagram showing the detection voltage obtained from each loop coil during the first detection operation. FIG. 9 is a timing diagram showing the subsequent detection operation, FIG. 9 is a main part configuration diagram showing the second embodiment of the present invention, and FIG. 10 is a diagram similar to FIG. 6 in the second embodiment. DESCRIPTION OF SYMBOLS 1... Position detection part, 11-1 to 11-48... Loop coil, 2... Selection circuit, 3... Connection switching circuit,
4... Input pen, 5... Cursor, 6... Transmitting circuit, 7... Receiving circuit, 8... Processing device, 41°51
...tuned circuit.

Claims (4)

[Claims] (1) A position detection unit including a large number of loop coils arranged in parallel in the position detection direction; a selection circuit that sequentially selects one loop coil from the large number of loop coils; and a predetermined selection circuit for the selected one loop coil. a transmitting circuit driven by an alternating current signal having a frequency of; and a tuning circuit including a coil and a capacitor and having a tuning frequency at the predetermined frequency or the frequency of its nth (=2, 3, ...) order harmonic. a plurality of position indicators, each having a plurality of position indicators; a receiving circuit that detects each frequency of the n-th harmonic; a connection switching circuit that alternately connects the selected one loop coil to the transmitting circuit and the receiving circuit; and each of the induced voltages generated in each loop coil. A position detection device comprising a processing device that calculates each designated position of a plurality of position indicators. (2) Equipped with a position indicator having a tuned circuit in which a phase difference between a voltage and a current with respect to one frequency among a predetermined frequency and its n-th harmonic frequency is generated in a selected one loop coil. 2. The position detection device according to claim 1, wherein the induced voltage is detected for each frequency of a predetermined frequency and its nth harmonic, and for each phase difference. (3) An X-direction and Y-direction position detection unit formed by arranging a plurality of loop coils in parallel in the X-direction and Y-direction, respectively;
X to sequentially select one loop coil in the direction and Y direction
a transmission circuit that drives one of the selected loop coils in the X and Y directions with an AC signal of a predetermined frequency; (=2, 3,...) A plurality of position indicators each having a tuning circuit whose tuning frequency is the frequency of the harmonic, and one loop coil in the selected X direction and Y direction. In the generated voltage, the predetermined frequency or its n(=2
, 3, . . .) a receiving circuit that detects an induced voltage having almost the same frequency as the frequency of the harmonic, for each of the predetermined frequency and the frequency of the n-th harmonic thereof, and the selected X direction. and a connection switching circuit in the X and Y directions that alternately connects one loop coil in the Y direction to the transmitting circuit and the receiving circuit, and a plurality of induced voltages generated in each of the loop coils in the X and Y directions. A position detection device comprising: a processing device for calculating designated positions of a position indicator in an X direction and a Y direction, respectively; (4) Equipped with a position indicator having a tuned circuit with a different phase difference between voltage and current with respect to one frequency of a predetermined frequency and its n-th harmonic frequency, The position detection device according to claim 3, wherein the induced voltage generated in the loop coil is detected for each predetermined frequency and its n-th harmonic frequency, and for each phase difference. .