JP2513683B2 - Position detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a position detection device that digitizes a position on a tablet pointed by a position pointing device.

(Prior Art) As a conventional position detecting device of this type, there are a tablet having a flat plate shape and generating an alternating magnetic field having different phases depending on positions, a coil and a capacitor set so as to be tuned to a fundamental frequency of the tablet. A drive circuit for generating an alternating magnetic field having a different phase on the tablet, and a reference excitation phase connected to the resonance circuit of the position indicator and supplied with a detection signal from the drive circuit. And a processing device that identifies the coordinates of the position indicated by the position indicator from the detection output of the phase detector and outputs the coordinate information (Japanese Patent Application Laid-Open No. 57-57). No. 94890).

Further, as another conventional position detection device, a tablet in which conductor groups arranged at regular intervals are insulated from each other and arranged in rows and columns, a driving battery, a control circuit, a variable frequency oscillator, a frequency changeover switch, and an AC magnetic field generator. Position indicator that has a coil for operation and that switches the frequency of the variable frequency oscillator by turning on / off the frequency changeover switch by pressing or releasing the coil, and each conductor by the alternating magnetic field generated by the position indicator. There is a device provided with means for detecting the induced electromotive force and its frequency, calculating the coordinate value of the position indicator on the tablet, and converting the frequency of the induced electromotive force into a predetermined value ( JP-A-60-21
(See Japanese Patent No. 5230).

Further, as still another conventional position detecting device, a drive line is arranged corresponding to each row of a dial plate (tablet) in which information such as a plurality of characters and symbols is arranged in a matrix, and each column is associated. A position indicator having a resonance circuit in which a sense line is arranged and a high-frequency current is sequentially passed through each of the drive lines and which does not normally resonate with the high-frequency current but resonates with the high-frequency current only when the tip is pressed. Then, when any information on the tablet is pressed for pointing, the position of the sense line where the induced voltage is generated by the mutual induction between the resonance circuit formed in the position indicator and the drive line and the sense line. In some cases, the row and column of the information designated by the position indicator, that is, the pressing coordinate of the position indicator is detected from the position of the drive line at that time (Japanese Patent Laid-Open No. 59-3537). See the bulletin).

(Problems to be Solved by the Invention) However, in the above-described first conventional device, a cord for connection is required between the resonance circuit of the position indicator and the position detector, which causes entanglement. In addition, it takes time to handle such as disconnection due to fatigue, and the operation state of the position indicator, for example, the state where the position to be measured is fixed by pressing the position indicator against the tablet (pen down state) There was a problem that could not be detected at all. The second conventional device can be cordless, but in order to detect the operation state of the position indicator,
It is necessary to provide a drive battery, a control circuit, a variable frequency oscillator, etc. to the position indicator, and the position indicator is heavy and large in size, which deteriorates operability. There was a problem that it was troublesome to handle because it needed to be charged. Furthermore, the third conventional device can be cordless, and the position indicator is provided with a driving battery, a control circuit, a variable frequency oscillator, etc. in order to detect the state in which the position indicator is pressed against the tablet. Although it is not necessary to provide it, on the contrary, there is a problem that the position cannot be detected at all without pressing the position indicator on the tablet, and the position cannot be confirmed before the position to be measured is fixed.

INDUSTRIAL APPLICABILITY The present invention has a position indicator that is not connected to anywhere, has good operability, enables highly accurate position detection, and can be used even if the position indicator and the tablet are separated from each other within a predetermined distance. An object is to provide a detection device.

In addition, the present invention is not connected to a position indicator anywhere, has good operability, enables highly accurate position detection, and can be used even if the position indicator and the tablet are separated from each other within a predetermined distance. It is also an object of the present invention to provide a position detection device that can take out information indicating the height of the position indicator on the tablet.

(Means for Solving the Problem) In the present invention, in order to achieve the above object, a position for transmitting and receiving a signal between a position indicator and a tablet, and detecting a coordinate value on the tablet pointed by the position indicator. A first tuning circuit, which is a detection device, indicates a position to be measured to the tablet which is constantly closed, and notifies a state in which the operator does not operate, and the first tuning circuit configured by the operation of the operator. 1. A position indicator having a tuning circuit different from that of No. 1 and a second tuning circuit for indicating a position to be measured to the tablet and for notifying the tablet of the position to be measured, and a plurality of loop coils And a radio wave generating means for generating a radio wave capable of being tuned by the first and second tuning circuits and a radio wave resulting from the tuning reflected from the first or second tuning circuit. A tablet having a radio wave detecting means, and an amplifying means for amplifying a plurality of induced voltages induced by the reflection in a plurality of loop coils constituting the radio wave detecting means such that a maximum voltage value thereof is within a predetermined range. And whether the operation is performed with a precision smaller than the arrangement interval of the plurality of loop coils, based on the plurality of induction voltages induced by the reflection in the plurality of loop coils constituting the radio wave detection means and amplified by the amplification means. Regardless of whether or not the position indicator indicates the coordinate value of the pointing position on the tablet, and the induced voltage induced by the reflection in the loop coil forming the radio wave detecting means and amplified by the amplifying means. As a result, the electric wave reflected from the position indicator to the tablet is reflected from either the first tuning circuit or the second tuning circuit. Detecting whether a radio wave, proposes a position detecting device that includes a tuned circuit determining means for detecting whether the operation of the operator has been made.

Further, in the present invention, in order to achieve the above object, a position detection device that transmits and receives a signal between a position indicator and a tablet and detects a coordinate value on the tablet pointed by the position indicator, First tuning circuit that is instructed to indicate to the tablet the position to be measured and notifies the tablet that the operator is not operating, and the first tuning circuit and tuning frequency configured by the operator's operation. And a second tuning circuit for indicating the position to be measured to the tablet and notifying the state of the operation by the operator, and a plurality of loop coils. The second tuning circuit has a radio wave generating means for generating a radio wave capable of being tuned, and a radio wave detecting means for detecting a radio wave due to the tuning reflected from the first or second tuning circuit. And let, amplified by a gain according to the plurality of induction voltage to the gain control signal induced by the reflection to a plurality of loop coils constituting the electric wave detection means,
A plurality of variable gain amplifying means for changing the gain by changing the gain control signal so that the maximum voltage value of the plurality of induced voltages after the amplification becomes a value in a predetermined range, and a plurality of elements forming the radio wave detecting means. The position indication regardless of whether or not the operation is performed with a precision smaller than the arrangement interval of the plurality of loop coils from the plurality of induced voltages induced in the loop coil by the reflection and amplified by the variable gain amplifying means. Position indicator from coordinate calculation means for obtaining the coordinate value of the indicated position on the tablet of the device, and the induced voltage induced by the reflection in the loop coil constituting the radio wave detection means and amplified by the gain variable amplification means. It is detected whether the radio wave reflected from the tablet to the tablet is a radio wave reflected from the first tuning circuit or the second tuning circuit. It is whether a tuning circuit discriminating means for detecting the, proposes a position detecting device without to detect the height of the position indicator from said gain control signal.

(Operation) According to the present invention, when a radio wave is generated from the radio wave generating means composed of a plurality of loop coils of the tablet, the radio wave is used for the first or second tuning circuit of the position indicator for specifying the position on the tablet. Tuned, that is, received, the first or second tuning circuit that received the radio wave transmits a similar radio wave,
That is, it reflects. The radio waves reflected by the first or second tuning circuit and caused by the tuning are detected by a radio wave detecting means including a plurality of loop coils of the tablet, and the maximum value of them is within a predetermined range. Regardless of whether or not the operation is performed by the coordinate calculating means, the coordinate value of the position indicated on the tablet of the position indicator is more precise than the arrangement interval of the plurality of loop coils. At the same time as the calculation, the tuning circuit determination means detects which of the first and second tuning circuits the radio wave reflected from the position indicator to the tablet is, and the operator's operation is performed. It is detected whether or not

Further, according to the present invention, the levels of the plurality of induced voltages induced in the plurality of loop coils constituting the radio wave detection means are the distance between the position indicator and the radio wave generation means and the radio wave detection means, that is, the position indicator. Of a plurality of induced voltages having a value corresponding to the height of the position indicator by a variable gain amplifying means for amplifying with a gain according to a gain control signal.
Amplification is performed until the maximum voltage value among them reaches a value in a predetermined range, and the height of the position indicator is detected from the gain control signal.

(Embodiment) FIG. 1 shows a first embodiment of a position detecting device according to the present invention. In FIG. 1, 1 is a position detecting unit, 2 is a selection circuit, 3 is a transmission / reception switching circuit, and 4 is a position indicator. Reference numeral 5 indicates a transmission circuit, reference numeral 6 indicates a reception circuit, and reference numeral 7 indicates a processing device.

In the position detecting section 1, a large number, for example, 48 loop coils 11-1, 11-2,..., 11-48 having conductors parallel to each other, are shown in the direction of arrow A in FIG. ). Further, each of the loop coils 11-1 to 11-
The 48's are arranged parallel to each other and overlapping.
Although each of the loop coils 11-1 to 11-48 has one turn here, it may have a plurality of turns if necessary. As the position detecting section 1, use is made of a large number of loop coils by connecting a large number of parallel conductors formed by, for example, etching processing on a well-known printed circuit board with jumper wires or the like. You can

The selection circuit 2 includes a plurality of loop coils 11-1 to 11-.
One of the loop coils is sequentially selected from 48. One end of each 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. Have been. The selection contact 23 corresponding to the terminal group 21 and the selection contact 24 corresponding to the terminal group 22 are linked with each other, operate based on information from the processing device 7, and select one loop coil. The selection circuit 2 is realized by combining a number of known multiplexers.

The transmission / reception switching circuit 3 alternately connects one loop coil selected by the selection circuit 2 to the transmission circuit 5 and the reception circuit 6, and the selection contacts 23 and 24 of the selection circuit 2 And 32 respectively.
Two output terminals of the transmission circuit 5 are connected to terminals 33 and 35, and two input terminals of the reception circuit 6 are terminals 34 and 36.
It is connected to the. Selection contacts 3 corresponding to the terminals 33 and 34
1 and the selection contacts 32 corresponding to the terminals 35 and 36 are interlocked with each other,
It operates based on a transmission / reception switching signal described later, and switches between transmission and reception. The transmission / reception switching circuit 3 is also realized by a known multiplexer.

The position indicator 4 is a stylus pen (hereinafter simply referred to as a pen) and has a tuning circuit 41 including a coil and a capacitor.

FIG. 2 shows a detailed structure of the pen 4. Inside the pen shaft 42 made of a non-metallic material such as a synthetic resin, a core body 43 such as a ballpoint pen and a core body 43 are slid from the tip end thereof. A tuning circuit including a ferrite core 44 having a through hole that can be freely accommodated, a coil spring 45, a switch 411, a coil 412 wound around the ferrite core 44, and capacitors 413 and 414.
41 and 41 are integrally combined and built in, and a cap 46 is attached to the rear end.

The coil 412 and the capacitor 413 are connected to each other in series as shown in FIG. 3 so as to form a well-known resonance circuit, and the numerical values of the coil 412 and the capacitor 413 are the same as the voltage at a predetermined frequency f0. The current phase is set to a value that causes resonance (tuning) in the same phase. Also capacitors
414 is connected in parallel to both ends of the capacitor 413 via a switch 411, and when the switch 411 is turned on,
It acts to delay the phase of the current in the above-mentioned resonant circuit and delay the phase of the received signal described later by a predetermined angle. The switch 411 holds the pen shaft 42 by hand or the like, and pushes the tip of the core body 43 into the pen shaft 42 by pressing the tip of the core 43 against an input surface (not shown) of the position detection unit 1. It is pressed via the coil spring 45 and is turned on.

Here, a first tuning circuit is provided, in which the circuit including the coil 412 and the capacitor 413 described above is constantly closed and instructs the tablet to indicate the position to be measured and notifies the operator that the operation is not performed. And also switch 41
1. A circuit composed of a coil 412 and capacitors 413 and 414 is constructed by an operator's operation (in this case, the core body 43 is pushed into the pen shaft 42 to turn on the switch 411), and the circuit is tuned to the first tuning circuit. A second tuning circuit is provided, which has a different frequency and indicates the position to be measured to the tablet and notifies the operator of the operation state.

FIG. 3 shows the details of the tuning circuit 41, the transmission circuit 5 and the reception circuit 6 as well as the configuration of the entire apparatus. In the figure, 51 is a timing circuit, 52 is a drive circuit, and these constitute the transmission circuit 5. , 601 is an amplifier, 602 is a reception timing switching circuit, 603 is a variable gain amplifier (PGA), 604 is a bandpass filter (BPF), 605 is a detector, and 606 and 607 are phase detectors (PGA).
SD), 608, 609, and 610 are low-pass filters (LPF), which form the receiving circuit 6.

The processing device 7 is composed of a well-known microprocessor or the like, controls the timing circuit 51, and
Control the switching of each loop coil, and a low-pass filter
Output values from 608 to 610 are analog and digital (A / D)
The variable gain amplifier 603 is converted so that the maximum digital value of the digital values corresponding to the output value of the low-pass filter 608 falls within a predetermined range, and the arithmetic processing described later is executed. The coordinate value of the position pointed by the pen 4 is calculated, and the tuning circuit is discriminated to identify the operating state of the switch.

Here, the position detection unit 1, the selection circuit 2, the connection switching circuit 3 and the transmission circuit 5 described above constitute a radio wave generating means, and the position detection unit 1, the selection circuit 2, the connection switching circuit 3 and the reception circuit 6 are The radio wave detecting means and the amplifying means are constituted, and the processing device 7 constitutes the coordinate calculating means and the tuning circuit discriminating means.

Next, the operation will be described. First, a description will be given of how the radio wave is transmitted and received between the position detecting unit 1 and the pen 4 and the signals obtained at this time with reference to FIG.

The timing circuit 51 has a rectangular wave signal A having a predetermined frequency f0, for example 500 kHz, a signal A '(not shown) obtained by delaying the phase of the rectangular wave signal A by a predetermined angle, a predetermined frequency fk, for example 15.6.
A 25 kHz transmission / reception switching signal B and a reception timing signal C are generated. The rectangular wave signal A is sent to the phase detector 606, converted into a sine wave signal by a low-pass filter (not shown) and sent to the drive circuit 52, and the rectangular wave signal A ′ is sent to the phase detector 607. Further, the transmission / reception switching signal B is transmitted to the transmission / reception switching circuit 3, and the reception timing signal C is further transmitted to the reception timing switching circuit 602.

The sine wave signal sent to the drive circuit 52 is converted into a balanced signal and sent to the transmission / reception switching circuit 3. The transmission / reception switching circuit 3 uses the driving circuit 52 and the amplifier 60 based on the transmission / reception switching signal B.
The transmission and reception switching circuit 3
The signal output to the selection circuit 2 is time T (= 2 / 2f
k), which is a signal D that outputs or does not output a signal of 500 kHz every 32 μsec.

The signal D is sent to the one loop coil 11-i (i = 1, 2, ... 48) of the position detector 1 through the selection circuit 2, and at this time, the loop coil 11-i is A radio wave based on the signal D is generated.

At this time, when the pen 4 is held in a substantially upright state, that is, in a used state near the loop coil 11-i of the position detecting section 1, the radio wave excites the coil 412 of the pen 4 and the tuning circuit 41 thereof is excited. An induced voltage E synchronized with the signal D is generated.

Thereafter, when the signal D enters a period in which there is no signal, that is, a reception period, and the loop coil 11-i is switched to the receiving circuit 6, the radio wave from the loop coil 11-i disappears immediately, but the induced voltage E Gradually attenuates according to the loss in the tuning circuit 41.

On the other hand, the current flowing through the tuning circuit 41 based on the induced voltage E causes the coil 412 to emit radio waves. Since the radio wave excites the loop coil 11-i connected to the receiving circuit 6 in reverse, an induced voltage due to the radio wave from the coil 412 is generated in the loop coil 11-i. The induced voltage is sent from the transmission / reception switching circuit 3 to the amplifier 601 only during the reception period, is amplified and becomes the reception signal F, and is further received by the reception timing switching circuit.
602.

The reception timing switching circuit 602 is supplied with the reception timing signal C which is substantially an inverted signal of the transmission / reception switching signal B, and outputs the reception signal F while the signal C is at the high (H) level, and outputs the low ( Since nothing is output during the L) level period, a signal G (substantially the same as the received signal F) is obtained at the output, and the signal G is sent to the variable gain amplifier 603.

As shown in FIG. 5, the variable gain amplifier 603 comprises a plurality of, here eight, resistors R for gain control, a well-known multiplexer MPX, and an amplifier AMP, and according to a control signal sent from the processing device 7. The multiplexer MPX is switched so that the gain between the input terminal IN and the output terminal OUT is controlled.

Initially, the variable gain amplifier 603 is controlled so that the gain is the smallest, that is, the bottom terminal of the multiplexer MPX is selected, and the signal at the gain (1/8 of the maximum gain) at this time is obtained. G is amplified and sent to the bandpass filter 604 as a signal H (the same as the signal G except for the amplitude) (note that the signals F, C, and H are shown as one waveform in FIG. 4, but actually The amplitude of signal H is different from the amplitude of signal G or F).

The bandpass filter 604 is a filter having a pass band centered on the frequency f0, and has a signal I (strictly speaking, an amplitude i corresponding to the energy of the frequency f0 component in the signal H).
In the state where several signals H are input to the bandpass filter 604 and converged, the signal H is sent to the detector 605 and the phase detectors 606 and 607.

The signal I input to the detector 605 is detected and rectified to form a signal J, and then a reduction filter 608 having a sufficiently low cut-off frequency has a voltage value Vx corresponding to approximately 1/2 of the amplitude i. The DC signal K is converted and sent to the processing device 7.

The processor 7 A / D-converts the DC signal K into a digital value, and the voltage value Vx of the signal K indicates a value proportional to the distance between the pen 4 and the loop coil 11-i. Since it changes when 11-i is switched, the loop coil 11-i is switched as described later, and the digital value of the voltage value Vx obtained for each loop coil is temporarily stored. At this time, the obtained voltage value It is determined whether or not a digital value corresponding to the maximum voltage value of Vx, for example, Dk is a preset predetermined range, for example, a value between the digital values Da and Db (Da> Db).

The digital values Da and Db have the strongest electromagnetic coupling between the tuning circuit 41 of the pen 4 and the loop coil 11-i closest to the pen 4 when the gain of the variable gain amplifier 603 is the smallest, That is, the value is set to a value including a digital value obtained when the tip of the core body 43 of the pen 4 is in contact with the input surface of the position detection unit 1.

At this time, the processor 7 determines that the digital value Dk is not a value between the digital values Da and Db, that is, the digital value Db.
If the digital value Dk is determined as below, the variable gain amplifier 603 is set so that the digital value Dk becomes a value between the digital values Da and Db.
Change the control signal to the multiplexer MPX.

After that, the processor 7 switches the loop coil 11-i again, A / D converts the voltage value Vx obtained for each loop coil, temporarily stores the digital value, and at this time, obtains the obtained voltage value Vx. Digital value corresponding to the highest voltage value of
When Dk becomes a value between the digital values Da and Db, the coordinate value of the position designated by the pen 4 is calculated by executing the arithmetic processing described later on the temporarily stored digital value.

On the other hand, the rectangular wave signal A is input to the phase detector 606 as a detection signal. At this time, the switch 411 is off and the phase of the signal I substantially matches the phase of the rectangular wave signal A. If so, a signal that is the signal I just inverted to the positive side (substantially the same as the signal J) is output. This signal is converted into a DC signal (substantially the same as the signal K) having a voltage value corresponding to approximately 1/2 of the amplitude i by the same low-pass filter 609 as described above, and is sent to the processing device 7.

Further, although the rectangular wave signal A ′ is inputted to the phase detector 607 as a detection signal, as described above, the switch 411 is used.
Is off and the phase of the signal I leads the phase of the rectangular wave signal A ′ by a predetermined angle, a signal having components on the positive side and the negative side is output. This signal is converted into a DC signal by the same low-pass filter 610 and sent to the processing device 7. However, since the output signal of the phase detector 607 has components on the positive side and the negative side, the signal of the low-pass filter 610 is The output voltage value is considerably smaller than the output voltage value of the low-pass filter 609.

Here, when the switch 411 of the pen 4 is turned on, the phase of the current flowing through the tuning circuit 41 is delayed with respect to the induced voltage E,
The phase of the received signal F is also delayed by a predetermined angle, that is, almost coincides with the phase of the rectangular wave signal A '. Therefore, the output I of the band-pass filter 604 at this time is made a signal having components on the positive side and the negative side by the phase detector 606, and the low-pass filter 60
The output of 9 has almost the same voltage value as the output of the low-pass filter 610 when the switch 411 described above is off, but the phase detector 6
The signal is inverted to the positive side by 07, and the low-pass filter 61
The output of 0 is a DC signal having a predetermined voltage value corresponding to approximately 1/2 of the amplitude i, as described above.

Thus, when the switch 411 is off, the low-pass filter 6
A predetermined voltage value is obtained at the output of 09, and switch 411
When is on, a predetermined voltage value is obtained at the output of the low-pass filter 610, so that in the processing device 7, the low-pass filter 60
By monitoring the output values of 9 and 610, switch 411
Is off or on.

Note that the information indicating the on (or off) state of the switch 411 identified here is used as information for specifying a value to be actually input among the coordinate values of the position specified by the pen 4.

As described above, when the maximum voltage value of the induced voltages obtained from the respective loop coils is not a value within a predetermined range set in advance, that is, the position detection unit 1 and the pen 4 are not in contact with each other, and a predetermined value is obtained. The position detection is performed because the variable gain sensitizer 603 is controlled so that the maximum voltage value is within the predetermined range even when the distance is within a distance (usually 2 to 3 cm). Even when a thick object such as a book is placed on the input surface of the section 1 and the coordinates are input using the pen 4 from above, the coordinate value of the specified position of the pen 4 is accurately obtained, and the switch The on / off of 411 can be identified.

Next, the position detection and the state of the pen 4, that is, the on / off state of the switch 411, in the apparatus of the present invention will be described with reference to FIGS.

First, when the power of the entire device is turned on and the measurement is started, the processing device 7 sets the loop coil 11-1 of the position detection unit 1 to a position.
Information for selecting the first loop coil 11-1 out of 11 to 48 is sent to the selection circuit 2 and the loop coil 11-1 is connected to the transmission / reception switching circuit 3. The transmission / reception switching circuit 3 alternately controls the switching of the loop coil 11-1 to the transmission circuit 5 and the reception circuit 6 based on the transmission / reception switching signal B described above.

At this time, the transmission circuit 5 operates in the transmission period of 32 μsec.
Sixteen 500 kHz sine wave signals as shown in FIG. 6 (a) are sent to the loop coil 11-1. The switching between transmission and reception is repeated 7 times for one loop coil, here 11-1 as shown in FIG. 6 (b). The repetition period of 7 times of transmission and reception is the selection period of one loop coil (44
8 μsec).

At the output of the reception timing switching circuit 602 of the reception circuit 6, an induced voltage is obtained for each loop coil every seven reception periods. As described above, this induced voltage is averaged by the bandpass filter 604. And the detector 605 and the phase detector 60
It is sent to the processing device 7 through 6,607 and the low-pass filters 608 to 610. At this time, the output value of the low-pass filter 608 is A / D converted and temporarily stored as a detection voltage proportional to the distance between the pen 4 and the loop coil 11-1, for example, Vx1 (actually, the low-pass filter is actually used. The output values of 609 and 610 are also A / D converted, but the values at this point are not adopted.)

Next, the processing device 7 sends information for selecting the loop coil 11-2 to the selection circuit 2, connects the loop coil 11-2 to the transmission / reception switching circuit 3, and is proportional to the distance between the pen 4 and the loop coil 11-2. The obtained detection voltage Vx2 is obtained and stored, and thereafter, the loop coils 11-3 to 11-48 are sequentially transmitted similarly to the transmission / reception switching circuit 3 in the same manner.
The detection voltages Vx1 to Vx48 proportional to the distance between each loop coil and the pen 4 as shown in FIG. 6 (c) (however, in FIG. 6 (c), only a part of the detected voltage is analog. Memorized).

As shown in FIG. 7, the actual detection voltage is obtained only in several loop coils before and after the position (xp) where the pen 4 is placed.

Of the voltage values of the stored detection voltage, the processing device 7
If the maximum voltage value is within the predetermined range, the coordinate value representing the designated position of the pen 4 is calculated from these voltage values as described later, and the maximum voltage value is within the predetermined range. If not, control the variable gain amplifier 603, and again
The above-described operation is repeated to obtain the detection voltages Vx1 to Vx48 proportional to the distance from the pen 4 for each loop coil, and the coordinate value representing the designated position of the pen 4 is calculated.

Next, the processing device 7 uses the loop coils 11-1 to 11-48.
Among them, information for selecting the loop coil for which the maximum detection voltage is obtained is sent to the selection circuit 2, and the transmission / reception of the radio wave is repeated a plurality of times, for example, 7 times, and at that time, the low-pass filter 609.
And output values obtained from 610 are A / D converted, and as described above, which of these values is greater than or equal to a predetermined value is detected, and the on / off state of the switch 411 is identified.

The on / off discrimination result of the switch 411 is transferred to a host device (not shown) together with the coordinate value indicating the specified position of the pen 4 described above.

When the first position detection and state identification are completed in this way, the processing device 7 performs the loop coil 11-1 to 11-48 as the second and subsequent position detection as shown in FIG.
Out of the loop coil from which the maximum detection voltage is obtained, a fixed number of information before and after the center, for example, information for selecting only 10 loop coils is sent to the selection circuit 2, and the output value is obtained in the same manner as described above. Position detection and switch for pen 4
The on / off state of 411 is identified, the obtained coordinate values and identification results are transferred and updated, and thereafter, these are repeated.

Therefore, when the pen 4 is operated on the position detection unit 1, all coordinate values of the position specified by the pen 4 during that time are transferred to the host device, and at this time, when the switch 411 is turned on,
The identification information in the ON state is transferred to the host device, and the host device can recognize the coordinate value at this time as a coordinate value to be input.

Further, in FIG. 8, the level check is to check whether the maximum value of the detected voltage is within the predetermined range and which loop coil has the detected voltage of the maximum value. If the value is not within the range, the subsequent coordinate calculation and the like are stopped, the control signal to the variable gain amplifier 603 is changed, and the center of the loop coil selected in the next position detection operation and state identification operation is set.

As one method of calculating the coordinate value xp, there is a method of approximating the waveform near the maximum value of the detection voltages Vx1 to Vx48 by an appropriate function, and obtaining the coordinates of the maximum value of the function.

For example, in FIG. 6C, the maximum detection voltage Vx3
And the detected voltages Vx2 and Vx4 on both sides thereof can be approximated by a quadratic function, it can be calculated as follows (however, the coordinate value of the center position of each loop coil 11-1 to 11-48 is x1 to
x48, and the interval is Δx. ). First, from each voltage and coordinate value, Vx2 = a (x2-xp) ² + b (1) Vx3 = a (x3-xp) ² + b (2) Vx4 = a (x4-xp) ² + b ... … (3) Here, a and b are constants (a <0). Further, x3−x2 = Δx (4) x4−x2 = 2Δx (5) Substituting equations (4) and (5) into equations (2) and (3) and rearranging, xp = x2 + Δx / 2 {(3Vx2-4Vx3 + Vx4) / (Vx2-2Vx3 + V
x4)｝ ... (6)

Therefore, the maximum value of the detection voltage obtained at the time of the level check and the detection voltages before and after that are extracted from each of the detection voltages Vx1 to Vx48, and these and the one of the loop coil from which the maximum value of the detection voltage is obtained are extracted. The coordinate value xp of the designated position of the pen 4 can be calculated by performing an operation corresponding to the above-described equation (6) from the coordinate value (known) of the previous loop coil.

FIG. 9 shows a second embodiment of the present invention, in which an example in which position detection in the X and Y directions is performed is shown. That is, in the figure, 1a is a position detection unit in the X and Y directions,
In this embodiment, two sets of the position detecting units 1 are stacked and their loop coils are superposed so as to be orthogonal to each other. 2a and 2b are selection circuits in the X and Y directions, 3a and 3b
Is an X-direction and Y-direction transmission / reception switching circuit, 52a and 52b are X-direction and Y-direction drive circuits, and 601a and 601b are X-direction and Y-directions.
Directional amplifiers, each having the same configuration as the selection circuit 2, transmission / reception switching circuit 3, drive circuit 52, and amplifier 601 in the first embodiment.

Reference numeral 53 denotes an XY switching circuit which applies a sine wave signal input from the timing circuit 51 via a low-pass filter (not shown) to one of the driving circuits 52a and 52b and selects a direction for position detection. belongs to. Further, reference numeral 611 is a reception timing switching circuit for selecting the reception timing along with the direction of detecting the reception signal from the amplifier 601a or 601b and adding it to the bandpass filter 604. Also, 7
Reference numeral a denotes a processing device, which is the same as the processing device 7 except that the XY switching circuit 53 and the reception timing switching circuit 611 are controlled so that position detection in the X direction and the Y direction is alternately performed. . It should be noted that the timing of the position detection operation and the state identification operation from the second time onward in the processing device 7a is set to 10th.
Shown in the figure.

As described above, according to the present embodiment, it is possible to easily detect the positions (coordinates) of the pen 4 in the two directions of the X direction and the Y direction. The other configurations and operations are similar to those of the first embodiment.

In addition, in the first or second embodiment, the low-pass filter
The output value of 608 is a value corresponding to the strength of electromagnetic coupling between the pen 4 and each loop coil of the position detection unit 1, and the maximum voltage value of the output values is the pen 4 and the position detection. The value is approximately proportional to the distance from the unit 1, that is, the height of the pen 4 on the position detecting unit 1. Therefore, the digital signal obtained by A / D converting the maximum voltage value of the output values of the low-pass filter 608 or the control signal of the processing device 7 for controlling the variable gain amplifier 603 is output to the high level on the position detecting unit 1 of the pen 4. It can also be sent to the higher-level device as information indicating the level.

In addition, in the first or second embodiment, the position detector 1
Alternatively, by attaching a microphone or the like to 1a and providing the processing device 7 or 7a with a voice recognition function, it is possible to perform various commands by voice. In the second embodiment, the processing device 7a is also used. Alternatively, the higher-level device may be provided with a character recognition function and used as a tablet for inputting handwritten characters.

Further, the number of loop coils and the arrangement thereof in the embodiment are merely examples, and it is needless to say that the present invention is not limited to this.

(Effect of the Invention) As described above, according to the present invention, the first and second tuning are performed with respect to the position indicator having the first and second tuning circuits having different tuning frequencies from the radio wave generating means of the tablet. The circuit generates radio waves that can be tuned, and is reflected from a first tuning circuit which is normally closed among the first and second tuning circuits or a second tuning circuit which is configured by an operation of an operator. The radio waves caused by the synchronization are detected by the radio wave detection means of the tablet, the maximum value of them is amplified by the amplification means so that the maximum value becomes a value within a predetermined range, and further the coordinate calculation means performs the operation regardless of whether or not the operation is performed. The coordinate value of the position indicated by the position indicator on the tablet is calculated with a finer precision than the arrangement interval of the plurality of loop coils, and the position is reflected from the position indicator to the tablet by the tuning circuit discrimination means. Since the detected radio wave is reflected from either the first or the second tuning circuit to detect whether or not the operator's operation is performed, the position indicator is tuned. It suffices to provide passive elements such as coils and capacitors to configure the circuit, and the code is no longer needed. Therefore, the code does not become entangled and obstructed, and the wire is not broken due to fatigue. No need for heavy parts such as, the weight and cost are reduced, the trouble of battery replacement is eliminated, the operability is extremely improved, and even if the position indicator and the tablet are separated Since each induced voltage can be obtained, therefore, even when a thick one, such as a book, is placed on the tablet and coordinates are input from the top, a smaller distance than the loop coil arrangement interval is used. The coordinate value on the tablet can be detected with high accuracy, that is, with high accuracy regardless of whether or not the operation is performed, and the coordinate value is detected together with the coordinate value detection depending on which tuning circuit reflects the radio wave. There are advantages such as being able to detect whether or not the operator has performed an operation.

Further, according to the present invention, the variable gain amplifying means amplifies the maximum value of the plurality of induced voltages detected by the radio wave detecting means to a value within a predetermined range, and the gain control signal in the variable gain controlling means is obtained. Since the height of the position indicator is detected more, the coordinate value of the position indicated on the tablet by the position indicator and the operation of the operator on the position indicator can be detected, and the height of the position indicator on the tablet can be detected. Can be detected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a position detecting device of the present invention, FIG. 2 is a sectional view of a stylus pen, and FIG. 3 is a device together with details of a tuning circuit, a transmitting circuit and a receiving circuit of the stylus pen. FIG. 4 is a diagram showing the entire configuration, FIG. 4 is a signal waveform diagram of each part of FIG. 3, FIG. 5 is a diagram showing details of a variable gain amplifier, and FIGS. 6 (a), (b) and (c) are first diagrams. FIG. 7 is a timing chart showing a basic position detecting operation in the embodiment, FIG. 7 is a diagram showing a detection voltage obtained from each loop coil in the first position detecting operation, and FIG. 8 is a second and subsequent positions. FIG. 9 is a timing chart showing the detecting operation and the state identifying operation, FIG. 9 is a view similar to FIG. 3 showing a second embodiment of the present invention, and FIG. 10 is a view similar to FIG. 8 in the second embodiment. Is. 1 ... Position detection unit, 11-1 to 11-48 ... Loop coil,
2 selection circuit, 3 transmission / reception switching circuit, 4 stylus pen, 5 transmission circuit, 6 reception circuit, 7 processing unit, 41 tuning circuit.

Continued on the front page (72) Inventor Toshihide Senzu 5-23-4 Sakurada, Washinomiya-cho, Kita-Katsushika-gun, Saitama

Claims (6)

(57) [Claims] 1. A position detecting device which transmits and receives a signal between a position indicator and a tablet, and detects a coordinate value on the tablet pointed by the position indicator, which is steadily closed and On the other hand, a first tuning circuit for indicating the position to be measured and notifying that the operator does not operate, and a tuning frequency different from the first tuning circuit configured by the operation of the operator and measuring the tablet A position indicator having a second tuning circuit for indicating a position to be performed and notifying a state in which the operator has operated, and a plurality of loop coils, wherein the first and second tuning circuits are tuned. A tablet having a radio wave generating means for generating a radio wave to be obtained and a radio wave detecting means for detecting a radio wave due to the tuning reflected from the first or second tuning circuit; Amplifying means for amplifying a plurality of induced voltages induced by the reflection in a plurality of loop coils constituting the plurality of coil coils so that a maximum voltage value thereof falls within a predetermined range, and a plurality of loops constituting the radio wave detecting means. The tablet of the position indicator irrespective of whether or not the operation is performed with a precision smaller than the arrangement interval of the plurality of loop coils by a plurality of induced voltages induced in the coil by the reflection and amplified by the amplifying means. Coordinate calculation means for obtaining the coordinate value of the above indicated position, and an induction voltage induced by the reflection in the loop coil that constitutes the radio wave detection means and amplified by the amplification means, and reflected from the position indicator to the tablet. It is detected whether the received radio wave is the radio wave reflected from the first tuning circuit or the second tuning circuit, and the operator does not operate. A position detecting device, comprising: a tuning circuit discriminating means for detecting whether or not there is a break. 2. The position detecting device according to claim 1, wherein the radio wave generating means and the radio wave detecting means are operated alternately. 3. The position detecting device according to claim 2, wherein the loop coil forming the electric wave generating means and the loop coil forming the electric wave detecting means are used in common. 4. A position detecting device which transmits and receives a signal between a position indicator and a tablet and detects coordinate values on the tablet pointed by the position indicator, the position detecting device being constantly closed and attached to the tablet. On the other hand, a first tuning circuit for indicating the position to be measured and notifying that the operator does not operate, and a tuning frequency different from the first tuning circuit configured by the operation of the operator and measuring the tablet A position indicator having a second tuning circuit for indicating a position to be performed and notifying a state in which the operator has operated, and a plurality of loop coils, wherein the first and second tuning circuits are tuned. A tablet having a radio wave generating means for generating a radio wave to be obtained and a radio wave detecting means for detecting a radio wave due to the tuning reflected from the first or second tuning circuit; A plurality of induction voltages induced by the reflection in the plurality of loop coils constituting the amplifier are amplified with a gain according to a gain control signal, and the maximum voltage value of the plurality of amplified induction voltages is within a predetermined range. A variable gain amplifying means for changing the gain control signal so as to change the gain, and a plurality of induced voltages induced by the reflection in a plurality of loop coils constituting the radio wave detecting means and amplified by the variable gain amplifying means. A coordinate calculation means for obtaining the coordinate value of the pointing position of the position indicator on the tablet regardless of whether or not the operation is performed with a precision smaller than the arrangement interval of the plurality of loop coils; and the radio wave detecting means. From the position indicator to the tablet from the induced voltage induced by the reflection in the loop coil constituting the amplifier and amplified by the variable gain amplifying means. A tuning circuit determining means for detecting whether the radio wave reflected by the first or second tuning circuit is a radio wave reflected by the operator, and detecting whether or not the operator has performed an operation. The position detecting device is characterized in that the height of the position indicator is detected from the gain control signal. 5. The position detecting device according to claim 4, wherein the radio wave generating means and the radio wave detecting means are alternately operated. 6. The position detecting device according to claim 5, wherein the loop coil forming the electric wave generating means and the loop coil forming the electric wave detecting means are used in common.