JPS63108426A - Position detector - Google Patents

Abstract

PURPOSE:To attain simultaneous use of plural indicators with excellent operability and high accuracy by sending plural radio waves from each coil of a position detection section and using a tuning circuit of the position detector to receive the generated radio waves thereby detecting the designated position. CONSTITUTION:When a loop coil 11-1 of a position detection section 1 is selected at first and a transmission circuit 6 is connected, plural radio waves of different frequency are generated. The radio wave excites coils of the position indicators 4, 5 and the tuning voltage is generated from the tuning circuits 41, 45. When the coil 11-1 is switched to the position of a reception circuit 7, plural radio waves are lost. The radio wave from the indicators 4, 5 is received by the circuit 7, the coil 11-1 is excited reversely and the induced voltages of the same frequency as that of the received radio waves are combined and generated. The transmission/reception of the radio wave is applied by switching all loop coils sequentially, and the less the distance with each indicator, the induced voltage is larger and a maximum at a position having the indicator. Each induced voltage is detected at each frequency by the circuit 7 and subject to arithmetic operation by a processing unit 8 and the coordinate of each indicated position is obtained respectively.

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 must be used at a fairly close distance.

In addition, although the position indicator can be made cordless in the latter device, the resolution of the coordinate position is determined by the line spacing,
If the distance between the lines is reduced in order to increase the resolution, the signal-to-noise ratio and stability will deteriorate, so 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. Furthermore, the position indicator had to be placed 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 selection circuit that sequentially selects one of the frequencies of the plurality of AC signals; a transmission circuit that drives the selected one loop coil with a plurality of AC signals having different frequencies; Among the voltages generated in the plurality of position indicators, each of which has a tuning circuit having a tuning frequency, and the selected one loop coil, an induced voltage having a frequency substantially the same as each frequency of the plurality of alternating current signals is selected. A receiving circuit that detects each frequency, a connection switching circuit that alternately connects the selected loop coil to the transmitting circuit and the receiving circuit, and a plurality of position instructions based on the induced voltages generated in each loop coil. The first invention comprises a processing device that calculates each specified position of the device, and a position detection section in the X direction and Y direction, which is formed by arranging a plurality of loop coils in parallel in the X direction and the Y direction, respectively, and the X direction and an X-direction and Y-direction selection circuit that sequentially selects one loop coil in the X-direction and Y-direction from a plurality of loop coils in the Y-direction; a plurality of position indicators each having a transmitting circuit driven by a plurality of alternating current signals having different values, and a tuning circuit including a coil and a capacitor and having a tuning frequency set to one frequency of each frequency of the plurality of alternating current signals; a receiving circuit that detects, for each frequency, an induced voltage having approximately the same frequency as each frequency of the plurality of alternating current signals among the voltages generated in one of the selected loop coils in the X direction and the Y direction;
an X-direction and Y-direction connection switching circuit that alternately connects the selected one loop coil in the X-direction and Y-direction to the transmitting circuit and the receiving circuit; The second invention includes a processing device that calculates designated positions of a plurality of position indicators in the X direction and Y direction from each induced voltage.

(Function) According to the first invention, one of the plurality of loop coils is selected by the selection circuit, a transmission circuit is connected to it by the connection switching circuit, and a plurality of alternating current signals having different frequencies are transmitted. When the loop coil is turned on, a plurality of radio waves are generated from the loop coil. The plurality of radio waves respectively excite coils in a plurality of position indicators that designate positions on the position detection unit,
An induced voltage synchronized with each frequency of the plurality of alternating current signals is generated in each tuned circuit. Thereafter, when a receiving circuit is connected to the selected loop coil by the connection switching circuit and the plurality of AC signals are disconnected, the plurality of radio waves disappear. On the other hand, a current having the same frequency as each of the plurality of AC signals applied to the one loop coil flows through the tuned circuit of each position indicator based on the generated voltage, and this current flows through the tuned circuit of each tuned circuit. Each coil generates radio waves. Since each radio wave reversely excites the one loop coil connected to the receiving circuit, induced voltages having the same frequency as each frequency of the plurality of alternating current signals are synthesized and generated in the one loop coil. Transmission and reception of the plurality of radio waves is repeated sequentially by switching the loop coils, but since this is performed by resonance between the loop coil and the coil of each position indicator, the distance between the loop coil and the coil of each position indicator is small. As the voltage increases, the voltage value of the induced voltage increases. Therefore, the position where the position indicator is placed (designated position)
An induced S voltage is generated in each loop coil for each position indicator, with the induced voltage generated in the loop coil closest to the specified position being the maximum value, and gradually decreasing as the distance from the specified position increases. The voltage value of each of the induced voltages is detected for each frequency by a receiving circuit, and further subjected to derivation processing by a processing device,
The coordinate values of the position where the voltage value reaches the maximum value, that is, the designated position of each position indicator, 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, the induced voltage based on the resonance between the loop coil and the coil of each position indicator is obtained in the X and Y directions, and from this, the induced voltage is determined in the X and Y directions for each position indicator. The coordinate values of the so-called two-dimensional designated position 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 () and () are operated in conjunction with each other and are operated based on a transmission/reception switching signal shown in (()) 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 body 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 the tip end. A ferrite core 44 with a through hole that can be freely 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.

The coil 412 and the capacitor 413 are connected in parallel with each other as shown in FIG. 4 to form a well-known parallel resonant circuit, and the values of the coil 412 and the capacitor 413 correspond to the first AC signal frequency f
1, the voltage and current phases are set to values that resonate (synchronize) in the same phase. Further, the capacitor 414 is connected to the coil 412 and the capacitor 41 through the switch 411.
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. In addition, when the switch 411 pushes the tip of the core 43 into the pen barrel 42 by pressing the tip of the core 43 to enable input of the position detection 8111 (not shown), the rear end causes the coil spring 4 to be pressed.
5, it is pressed and turned on.

・Figure 3 shows the detailed structure of the cursor 5. At one end of the casing 52 made of a non-metallic material such as synthetic resin, there is a transparent cylinder made of plastic or the like with a "+" indicator on the bottom. A body 53 is attached, 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,
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 cooler coils. The switch 511. Coil 512. Tuning circuit 51 is connected to capacitors 51315 and 514.

The coil 512 and the capacitor 513 are the 41171st
As shown in FIG. is set to a value that resonates (tunes) in the same phase. In addition, the capacitor 514
is connected to both ends of the coil 512 and capacitor 513 via a switch 511, and when the switch 511 is turned on, the phase of the current in the parallel resonant circuit described above is changed to a predetermined angle.

For example, a delay effect of 90' is performed.

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 and 602 are waveform shaping circuits, and 603
, 604 is a phase shifter, and 605 is a drive circuit, which constitute the transmitting circuit 6. Further, 701 is an amplifier, 70
2, 703 is a bandpass filter (BPF), 704
, 705 , 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 or the like, and includes the first. It generates a second 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 bezel 4. The manner in which radio waves are transmitted and received between the cursor 5 and the signals to be removed will be explained with reference to FIG.

The processing device 8 generates a first alternating current signal, for example, a rectangular wave signal, at a frequency f1, for example, 500kl-IZ, based on a clock from an oscillator (not shown), and also generates a first alternating current signal, for example, a rectangular wave signal, at a frequency f2.
．． For example, a second alternating current signal, for example a square wave signal B, having a frequency of 625 kHz is generated, and a second alternating current signal having a frequency of 15.625 kHz is generated.
Generates a Hz transmission/reception switching signal C.

The rectangular wave signals A and B are sent to waveform shaping circuits 601 and 602, respectively, where their waveforms are shaped, and then roughly passed through a phase shifter 603.
, 604, respectively. The phase shifter 603 creates a signal with the phase of the rectangular wave signal Δ unchanged (Oo) and a signal A- (not shown) delayed by 90 degrees, and sends these to phase detectors 704 and 705, respectively. ,
Further, the phase shifter 604 outputs a signal with the phase of the rectangular wave signal B unchanged (0°) and a signal B1 delayed by 90'.
(not shown) and sends them to phase detectors 706 and 701, respectively.

On the other hand, the rectangular wave signals A and B are converted into balanced signals by the drive circuit 605 and sent to the connection switching circuit 3, but since the connection switching circuit 3 is switched and controlled by the signal C, the connection switching circuit 3 The signals outputted to the selection circuit 2 are a signal D that outputs or does not output a 500kHz pulse signal every 32μsec, and a signal D that outputs or does not output a 500kHz pulse signal every 32μsec.
The signal E is a signal that outputs or does not output a 625kHz pulse signal every c.

The signal R and E are sent to one loop coil, for example 11-1, of the position detection unit 1 via the selection circuit 2, but at this time, the loop coil 11-1 selects a signal based on the signal R and E. ku゛4 He is generated.

At this time, if the input vent 4 is held in a substantially upright state near the loop coil 11-1 of the position detection section 1, the radio waves generated by the signal excites the coil 412 of the input vent 4, and its tuning circuit 41 An induced voltage F synchronized with the signal is generated. On the other hand, the radio wave generated by the loop coil 11-1 based on the signal E excites the coil 512 of the cursor 5 placed at another position on the position detection unit 1, and the tuned circuit 51 receives the signal. Generates an induced voltage G synchronized with E.

After that, when the loop coil 11-1 is switched to the receiving circuit 7 side at the time when the no-signal period, that is, the receiving period starts at signal L and E, the 41 wave from the loop coil 11-1 disappears immediately. In the tuning circuit 41 of the input ben 4 and the tuning circuit 51 of the cursor 5, since there is no change in circuit terms, the induced voltages F and GLJ gradually attenuate.

On the other hand, the current flowing through the tuned circuits 111 and 51 based on the induced voltages F1J-3 and G is
and 512 respectively transmit 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 H 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 C, the loop coil 1 is switched only during the transmission stop period.
Take in the induced voltage H from 1-1. The induced voltage H is amplified by an amplifier 701 and further passed through a bandpass filter 702.
and 703.

Since the bandpass filter 702 is a filter having a passband centered at the frequency f1, only the voltage component induced by the tuning circuit 41 in the signal H appears in its output I, and similarly, the bandpass filter 703 has a passband centered at the frequency f1. Since the filter has a central passband, only the voltage component induced by the tuning circuit 51 in the signal H appears in its output J.

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

The rectangular wave signal A is input as a detection signal to the phase detector 704, and at this time, if the phase of the signal I matches the phase of the rectangular wave signal A, the signal ■ has just been inverted to the positive side. Outputs signal K. This signal is converted into a flat signal of voltage VL by a low-pass filter 108 whose cut-off frequency is sufficiently low.

Furthermore, the phase detector 705 receives a rectangular wave signal - as a detected signal. At this time, if the phase of the signal I matches the phase of the rectangular wave signal A', the signal Outputs an inverted signal to the positive side. 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 B is input to the phase detector 706 as a detected signal, and at this time, if the phase of the signal J matches the phase of the rectangular wave signal @B, the signal J is exactly on the positive side. The inverted signal M is output. The signal M is converted into a flat signal N of voltage VN by a low-pass filter 710 whose cut-off frequency is sufficiently low.

Further, the rectangular wave signal @B' is inputted to the phase detector 705 as a detection signal, and at this time, if the phase of the signal J matches the phase of the rectangular wave signal B1, the signal J Outputs a signal that is inverted to the positive side. This signal is converted into a flat signal by a low-pass filter 711 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 I and J and the rectangular wave signals A and B 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 709 and 711.

Furthermore, in the input pen 4, when the switch 411 is on, the phase of the current at the resonant frequency of the tuning circuit 41 lags the phase of the voltage by 90' as described above, and the received signal ■ 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 on at the cursor 5, the phase of the current at the resonant frequency of the tuned circuit 51 lags the phase of the voltage by 90 degrees, as described above, and the phase of the received signal J is also delayed by 90° with respect to the phase of the rectangular wave signal B. Therefore, at this time, a voltage appears only at the output of the low-pass filter 711 (note that if the phase delay at this time is less than 90',
A voltage value corresponding to the phase delay width appears at both the outputs of the low-pass filters 710 and 711.

).

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 is the AD-1
The following formula (1) is used for the output values of converters 712 and 713 and the output values of AD converters 714 and 715.
, performs the arithmetic processing shown in (2).

VR= (VP +VQ 2) 1/2...-(1
)V=jan(VQ/VP)...
(2) θ Here, vp is the output value of the AD converter 712 (or 714), and VQ is the output value of the AD converter 13 (or 715). Further, the voltage VR indicates a value proportional to the distance between the input pen 4 (or cursor 5) and the loop coil 11-1, and is the voltage ■. indicates a value proportional to the phase difference between the voltage and current in the tuning circuit 41 of the input pen 4 (or the tuning circuit 51 of the cursor 5).

The value of the voltage VR changes when the input pen 4 (or cursor 5) and the loop coil 11-1 that transmits and receives radio waves are switched, and from this, the position of the input pen 4 (or cursor 5) changes as described later. Detected.

Since the value of the voltage ■ 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 C 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 500kHz7 as shown in FIG. ) is sent to the loop coil 11-1, and at the same time, although not shown, 20
pulse signals (only five of them are shown in FIG. 5 for convenience of drawing).

The switching between transmission and reception is repeated seven times for one loop coil, here 11-1, as shown in FIG. 6(1)). This seven-time transmission and reception repetition period is
This corresponds to the selection period (448 μsec) of one loop coil.

At the outputs 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-. 711, and the AD converter 7
12 to 715 into digital values, and processed by the processing device 8.
will be sent to. At this time, AD converters 712, 71
The output value of 3 is converted into a detection voltage proportional to the distance between the input pen 4 and the loop coil 11-1, for example, V, 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 by 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 pen 4 and the loop coil 11-2 in the same manner as described above. A detection voltage VR2 proportional to the distance from the object is obtained and stored.

Thereafter, similarly, the loop coils 11-3 to 11-48 are sequentially connected to the connection switching circuit 3, and the detected voltage is proportional to the distance from the input pen 4 for each loop coil as shown in FIG. 6(C). (2) Storing R1 to VR48 (however, only a part of them is shown in analog representation in FIG. 6(C)).

The actual detected voltage is obtained only from several loop coils before and after the position a(xp) 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 relative to the input pen 4 and cursor 5 is detected, 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 each of the detection voltages VR1 to V 1148 for the input pen 4 (or cursor 5), as well as the tuning circuit 41 of the input pen 4 (or the tuning circuit 5 of the cursor 5).
Detection voltage proportional to the phase difference between voltage and current in 1) ■
. is calculated by the arithmetic 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
By approximating the detection voltages Vr12 and VR4 on both sides thereof using 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 ~x48, and the interval is ΔX). First, from each voltage and coordinate value, VR2=a(x2-xp) +b ・-・-(
3) VR3=a(x3-xp) +b −・−
・-C, 4) VR4=a (x4-xp) +b
-(5). Here, a and b are constants (a<O
).

Also, x3-x2 = , dx...
・(6)x4-X2=27X...(7). By substituting equations (6) and (7) into equations (4) and (5), we get Xp = x2+Δx/2 ((3VR2-4VR3+V
R4) / (VR2-2VR3+VR4) )...
...(8) becomes.

Therefore, from each detection voltage VR1 to VR48, the maximum detection voltage obtained during the level check and the detection voltages before and after it are extracted, and these and the detection voltage of the loop coil from which the maximum detection voltage was obtained are extracted. The coordinate value xp of the specified position of the input pen 4 is calculated by performing the calculation equivalent to the above-mentioned equation (8) from the coordinate value (known) of the previous loop coil.
can be calculated, and in the same way, the coordinate values of the specified position of the cursor 5 can be calculated.

Further, as mentioned above, the detection voltage for the input pen 4 is A
The detection voltage for the cursor is obtained from the D converters 712 and 713, 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, a tuned circuit having a tuning frequency f1 and a phase difference of 0° between voltage and current, a tuning circuit having a tuning frequency f1 and a phase difference of 90°, a tuning circuit having a tuning frequency f2 and a phase difference of 0°, and tuning frequency f2 and phase difference 9
Prepare position indicators each having a tuning circuit of 0゛,
If the processing device 8 performs the arithmetic processing of equation (8) for each output value of the AD converters 712 to 715, four position instructions can be obtained without changing the configuration of the transmitting circuit 7 or the receiving circuit 8. It is also possible to detect the position of the device at the same time.

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 and 607 are XY switching circuits, which transfer the AC signals from the phase shifters 603 and 604 to the drive circuit 605a.
or 605b, and also to select the direction to be detected.

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. Note that the second
The timing of the coordinate detection operation after the first time is shown in FIG. As described above, according to this embodiment, the position (coordinates) of the input ben 4 and the cursor 5 in two directions, the X direction and the Y direction, 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, the loop coil of the position detection section detects a plurality of positions each having a tuning circuit whose tuning frequency is one of the frequencies of the plurality of alternating current signals. In addition to transmitting multiple radio waves to the indicator, a loop coil receives the radio waves sent in the opposite direction from each tuned circuit, and the induced voltage generated at this time is detected for each frequency, and this is sent to a large number of loop coils. Follow all of the
Since the designated position of each position indicator is detected from the many induced voltages obtained, multiple position indicators can be detected individually, and multiple coordinate values can be input at the same time. When inputting a figure by providing a selection area for various commands, you can input the shape of the figure with one position indicator while specifying the type and color of the line segment with the other position indicator. It is not necessary to greatly move the position of one position indicator each time the various designations are made, as is the case in the past, and a device with good operability can be realized.

In addition, it is only necessary to install a tuning circuit whose main elements are a coil and a capacitor on the position indicator side, eliminating the need for cords and heavy parts such as batteries and magnets.
This improves operability, and because the position detection unit does not require any special parts, it can be made larger and can be applied to electronic whiteboards, etc., and it is also possible to perform arithmetic processing on a large number of induced voltages. By increasing the accuracy, the position detection accuracy can be increased. 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. )(bHc)
7 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 timing diagram showing the detection voltage obtained from each loop coil during the first detection operation. FIG. 9 is a main part configuration diagram showing a 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 detecting section 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; a plurality of position indicators each having a transmitting circuit driven by a plurality of alternating current signals having different values, and a tuning circuit including a coil and a capacitor and having a tuning frequency set to one frequency of each frequency of the plurality of alternating current signals; a receiving circuit that detects, for each frequency, an induced voltage having a frequency substantially the same as each frequency of the plurality of alternating current signals among the voltages generated in the selected one loop coil; A position detection device comprising: a connection switching circuit alternately connected to the transmitting circuit and the receiving 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. (2) Equipped with a position indicator having a tuned circuit with a different phase difference between voltage and current for one frequency of each frequency of a plurality of alternating current signals, and controlling the induced voltage generated in the selected one loop coil. 2. The position detection device according to claim 1, wherein detection is performed for each frequency and 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
and a transmission circuit that drives one of the selected loop coils in the X and Y directions with a plurality of alternating current signals having different frequencies; a plurality of position indicators each having a tuning circuit whose tuning frequency is one of the frequencies; and a plurality of AC signals in the voltage generated in one of the selected loop coils in the X direction and the Y direction. a receiving circuit that detects an induced voltage of approximately the same frequency as each frequency for each of the frequencies; and a Y-direction connection switching circuit, and a processing device that calculates designated positions of a plurality of position indicators in the X-direction and Y-direction from the respective induced voltages generated in each loop coil in the X-direction and Y-direction. Position detection device. (4) Equipped with a position indicator having a tuned circuit with a different phase difference between voltage and current for one frequency of each frequency of a plurality of alternating current signals, and installed in a selected loop coil in the X direction and the Y direction. 4. The position detection device according to claim 3, wherein the generated induced voltage is detected for each frequency and each phase difference.