JP3249861B2 - Position detecting device and position indicator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a position detecting device using radio waves.

[0002]

Prior to this application, the applicant filed Japanese Patent Application No. Sho 61
No. 213970 (refer to Japanese Patent Application Laid-Open No. 63-70326) (hereinafter referred to as the prior application 1), a radio wave is exchanged between a sensing unit and a position indicator to thereby indicate a position indicated by the position indicator. We proposed a position detection device that calculates the coordinate value of.

[0003] To briefly explain the contents of the prior application 1, a loop coil of the sensing unit transmits radio waves of a predetermined frequency.
The radio wave is received by a resonance circuit provided in the position indicator. At this time, a radio wave transmitted from the resonance circuit that has received the radio wave is received by the loop coil to generate an induced voltage.
This is repeated by sequentially switching a plurality of loop coils of the sense section, and the coordinate value of the designated position is obtained based on the level of the induced voltage generated in each loop coil.

In this type of position detecting device, in addition to the coordinate value of the designated position, information indicating a state where the designated position to be actually input is specified (pen down state), the type of the position indicator, for example, a pen or a cursor. Or information for changing parameters other than coordinate values, such as the thickness of a line, hue and density (brightness) of a designated position or designated region, depending on software, together with the coordinate value of the designated position. There is a request to enter.

[0005] In the above-mentioned prior application 1, by connecting another capacitor to a coil and a capacitor constituting a resonance circuit via a manual switch, the resonance frequency is slightly changed according to the operation on the switch. This slight change in the resonance frequency is detected as a change in the phase angle, and the various types of information described above (hereinafter, referred to as indicator information).
And

However, in the device of the prior application 1, the range of the detectable phase angle is limited to about −60 ° to + 60 °, and the inductance of the coil and the capacitance of the capacitor change due to a change in ambient temperature and the like. Therefore, due to the problem that the phase angle at the time of the detection has to have a certain width, the number of inputtable indicator information cannot be increased so much. In the case of continuously changing, there is a problem that indicator information other than pen pressure information cannot be input at all.

Further, as an application of the prior application 1, Japanese Patent Application No. 63-308712 (refer to Japanese Unexamined Patent Application Publication No. 2-155019) (hereinafter referred to as prior application 2) resonates according to the pen pressure. A position indicator having a resonance circuit capable of changing the frequency continuously within a predetermined frequency range and changing the frequency range to one of a plurality of different frequency ranges according to ON / OFF of a side switch. We have proposed a device that can input multiple pieces of pen pressure information for different purposes or pen pressure information and other information using a device.

However, in the above-described apparatus of the prior application 2, since the range of the phase angle with respect to the predetermined frequency is divided into a plurality of different frequency regions according to the on / off of the side switch, the pen pressure can be detected. As the range becomes smaller, the phase angle with respect to one pen pressure when the side switch is turned on and the phase angle with respect to the one pen pressure when the side switch is turned off are completely different, so that the pen pressure information for the phase angle can be corrected. There is a problem that different correction values are required for each.

Further, as an application of prior application 2, Japanese Patent Application No. 4-36508 (hereinafter, referred to as prior application 3) discloses a method in which the center of a resonance frequency is set in advance in accordance with a switch operation. And a position indicator having a resonance circuit whose resonance frequency changes continuously around at least one of the plurality of frequencies according to the pen pressure while changing to any one of the above frequencies. Transmitting a radio wave of a plurality of frequencies to the device, receiving a radio wave reflected from the resonance circuit, detecting a coordinate value and a phase angle of a designated position from the radio wave, and setting the resonance frequency of the resonance circuit to the plurality of frequencies. By determining which of the above, a plurality of pen pressure information or pen pressure information and other information can be input, without reducing the range in which pen pressure can be detected, and It was proposed device capable of easily correcting the pen pressure information for the phase angle.

[0010]

However, in the device of the above-mentioned prior application 3, the center frequencies of the plurality of resonance frequencies that change according to the switch operation do not overlap each other when the resonance frequencies change according to the pen pressure. Since it is necessary to set a plurality of frequencies apart from each other, it is necessary to adjust a plurality of resonance frequencies and to require a wide frequency range.

In view of the above-mentioned conventional problems, the present invention makes it easy to adjust the configuration of the position indicator and the resonance frequency, and furthermore, it does not require a wide frequency range, and the indicator information, especially the pen pressure information and other information. An object of the present invention is to provide a position detection device capable of inputting information and a position indicator thereof.

[0012]

According to the present invention, there is provided a position detecting device for detecting a pointing position of a position indicator having a resonance circuit including at least a coil and a capacitor. A radio wave transmitting means for transmitting an electric wave for exciting the resonance circuit, while connecting an integrating circuit including at least a capacitor via a switch means and a rectifying circuit connected in series to each other,
Radio wave receiving means for receiving a radio wave generated from the resonance circuit, and state identification means for detecting a temporary change in the level of the radio wave received by the radio wave receiving means and identifying that the switch means has been operated Is proposed.

Further, according to the present invention, in a position detecting device for detecting an indicated position of a position indicator having a resonance circuit including at least a coil and a capacitor, the resonance frequency of which changes according to the pen pressure, in parallel with the resonance circuit, A radio wave transmitting unit for transmitting a radio wave for exciting the resonance circuit and a radio wave transmission unit for transmitting a radio wave for exciting the resonance circuit, while connecting an integration circuit including at least a capacitor through a switch unit and a rectification circuit connected in series to each other. A first state identification unit that detects a temporary change in the level of a radio wave received by the radio wave reception unit and identifies that the switch unit has been operated; Phase difference detection means for detecting a phase difference between a radio wave to be transmitted and a radio wave received by the radio wave reception means; and a brush based on the phase difference detected by the phase difference detection means. Suggest position detecting apparatus having a second state identification means for detecting.

[0014]

According to the present invention, the radio wave transmitted from the radio wave transmitting means excites the resonance circuit of the position indicator and gives electromagnetic energy to the resonance circuit. At this time, when the switch means of the position indicator is operated, a part of the induced voltage generated in the resonance circuit by the electromagnetic energy given to the resonance circuit is rectified through the rectification circuit, and the capacitor of the integration circuit is changed. Start charging. The charging of the capacitor is performed until the induced voltage generated in the resonance circuit substantially matches the terminal voltage of the capacitor. During the charging period, the electromagnetic energy stored in the resonance circuit decreases, and the capacitor generates a voltage. The strength of the radio wave is also weakened. As a result, the level of the radio wave received by the radio wave receiving means changes temporarily, and this is detected by the state identifying means, and the operation of the switch means is identified.

According to the present invention, the operation of the switch means is identified in the same manner as described above, and when the writing pressure on the position indicator changes and the resonance frequency of the resonance circuit changes, the phase difference detection means changes the radio wave. The phase difference between the radio wave transmitted from the transmission unit and the radio wave received by the radio wave reception unit is detected, and the pen pressure is detected from the phase difference by the second state identification unit.

[0016]

FIG. 1 shows a first embodiment of the present invention.
In the figure, 11a is a coil, 11b is a capacitor, 12a is a resistor, 12b is a capacitor, 13 is a switch, and 14 is a diode, and these constitute a position indicator A. 21-1, 21-2, 21-3 and 21-4 are loop coils, 22 is a selection circuit, 23 is an auxiliary antenna coil,
24 is an oscillator, 25 is a current driver, 26 and 27 are switching connection circuits, 28 and 29 are reception amplifiers, 30 and 31 are band-pass filters (BPF), 32 and 33 are detectors,
4 and 35 are low-pass filters (LPF), 36 and 37 are sample-and-hold (S / H) circuits, 38 and 39 are analog-to-digital (A / D) conversion circuits, and 40 is a processing unit (C
PU), and these constitute a position detecting device B (excluding the position indicator A).

The coil 11a and the capacitor 11b are connected in series with each other to constitute a known resonance circuit 11 having a predetermined resonance frequency fo. Resistance 12a
The capacitor 12b and the capacitor 12b are connected in series with each other to form a well-known integration circuit 12. The resonance circuit 11 and the integration circuit 12 are connected in parallel via a switch 13 and a diode 14 connected in series. Here, the diode 14 extracts a DC voltage from the induced voltage generated in the resonance circuit 11 while the switch 13 is on, and supplies the DC voltage to the integration circuit 12. The time constant of the integrating circuit 12 is initially
When there is no electric charge at all, the terminal voltage of the capacitor 12b is set to be substantially equal to the induced voltage generated in the resonance circuit 11 during one radio wave transmission / reception period described later.

The loop coils 21-1 to 21-4 are arranged side by side substantially parallel to each other in the position detection direction, and one end of each is connected to the selection circuit 22, and the other end is commonly grounded. I have. The selection circuit 22 receives the loop coil 21-1 in accordance with a predetermined selection signal applied from the processing device 40.
21-4, one loop coil is sequentially selected. The auxiliary antenna coil 23 includes loop coils 21-1 to 21-4.
, One end of which is connected to the switching connection circuit 27, and the other end is grounded.

The oscillator 24 generates an AC signal having the above-mentioned frequency fo and sends it to the current driver 25. The current driver 25 converts the AC signal into a current and sends it to the switching connection circuit 27. The switching connection circuit 26 is a processing device 4
One loop coil selected by the selection circuit 22 is connected to the receiving amplifier 28 or grounded in accordance with a predetermined switching signal applied from 0. The switching connection circuit 27 alternately switches and connects the current driver 25 and the receiving amplifier 29 to the auxiliary antenna coil 23 according to a predetermined switching signal applied from the processing device 40.

The receiving amplifier 28 generates a signal in the selected one of the loop coils, and selects the selecting circuit 22 and the switching connection circuit 26.
, And sends the amplified voltage to the band-pass filter 30. The receiving amplifier 29 amplifies the induced voltage generated in the auxiliary antenna coil 23 and transmitted through the switching connection circuit 27, and transmits the amplified voltage to the bandpass filter 31. Bandpass filters 30, 3
Reference numeral 1 designates the frequency fo as a center frequency, and extracts only components near the frequency fo from the above-mentioned induced voltage and sends them to the detectors 32 and 33.

The detector 32 detects the induced voltage generated in the one loop coil, that is, the received signal, and
4, and the detector 33 detects the induced voltage generated in the auxiliary antenna coil and sends it to the low-pass filter 35. The low-pass filters 34 and 35 have the frequency fo described above.
It has a much lower cutoff frequency and the detectors 32, 3
3 is converted into a DC signal, and the S / H circuits 36, 3
7 The S / H circuits 36 and 37 hold the voltage values at predetermined timings of the output signals of the low-pass filters 34 and 35 described above, specifically, at predetermined timings during the reception period, in accordance with the sampling signal applied from the processing device 40. Then, the signals are sent to A / D conversion circuits 38 and 39.

The A / D conversion circuits 38 and 39 convert the outputs of the S / H circuits 36 and 37 from analog to digital, and send them to the processing unit 40. The processing device 40 includes the loop coils 21-1 to 21-21 converted into the digital values.
The coordinate value of the position indicated by the position indicator A is calculated based on the level of the voltage value of the induced voltage corresponding to -4, and the change of the voltage value of the induced voltage of the auxiliary loop coil 23 converted into the digital value is calculated. Switch 1 of position indicator A based on
3 is turned on.

FIG. 2 shows a flow of processing in the processing device 40, and FIG. 3 shows an example of a transmission signal and a reception signal in the auxiliary antenna coil 23. The operation will be described.

First, it is detected whether or not the position indicator A is within the effective reading area of the position detecting device B. More specifically, the auxiliary antenna coil 23 is connected to a current driver 25 via a switching connection circuit 27, and an alternating current having a frequency fo is supplied from an oscillator 24.
3 generates a radio wave having a frequency fo.

At this time, assuming that the position indicator A is within the effective reading area of the position detector B, the radio wave excites the coil 11a of the position indicator A and gives electromagnetic energy to the resonance circuit 11. At this time, the processing device 40 does not send the selection signal to the selection circuit 22, and the switching connection circuit 26 grounds the input terminal of the reception amplifier 28 during the radio wave transmission period. Nothing appears in the output.

Thereafter, when the auxiliary antenna coil 23 is connected to the receiving amplifier 29 via the switching connection circuit 27, the generation of radio waves from the auxiliary antenna coil 23 stops.

On the other hand, if the switch 13 is off in the position indicator A, all the electromagnetic energy given to the resonance circuit 11 is accumulated in the resonance circuit 11 and supplied to the coil 11a. From this the frequency fo
To generate radio waves. Since the radio wave excites the auxiliary antenna coil 23 in reverse, an induced voltage of the frequency fo is generated in the auxiliary antenna coil 23.

The induced voltage generated in the auxiliary antenna coil 23 is amplified by a receiving amplifier 29, sent to a detector 33 via a band-pass filter 31, and detected.
Further, it is sent to the processing device 40 as a voltage value through the low-pass filter 35, the S / H circuit 37, and the A / D conversion circuit 39. The processing device 40 compares the level of the voltage value sent from the A / D conversion circuit 39 with a predetermined threshold level. Is determined to be outside the effective reading area if it is less than the threshold level. However, since a voltage value equal to or higher than the threshold level should be obtained here, the position indicator A is determined to be within the effective reading area. I do.

As described above, when it is determined that the position indicator A is in the valid reading area, the operations of coordinate detection and switch determination are started.

Specifically, first, the auxiliary antenna coil 23 is connected to the current driver 25 via the switching connection circuit 27 in the same manner as described above, and an alternating current having a frequency fo is supplied from the oscillator 24. Frequency f
o is generated, and the radio wave is generated by the coil 1 of the position indicator A.
1 a is excited to give electromagnetic energy to the resonance circuit 11. At this time, the selection circuit 22 selects one loop coil from the loop coils 21-1 to 21-4 based on the selection signal from the processing device 40.
During the transmission of the radio wave, the input terminal of the receiving amplifier 28 is grounded, so that the signal generated in the one loop coil is not transmitted to the receiving amplifier 28.

Thereafter, when the auxiliary antenna coil 23 is connected to the receiving amplifier 29 via the switching connection circuit 27, the generation of radio waves from the auxiliary antenna coil 23 stops.

Here, assuming that the switch 13 is continuously turned off on the position indicator A side, all the electromagnetic energy applied to the resonance circuit 11
1 and supplied to the coil 11a to generate a radio wave having a frequency fo. Since the radio wave excites the auxiliary antenna coil 23 in reverse with the selected one loop coil, an induced voltage of the frequency fo is generated in the one loop coil and the auxiliary antenna coil 23.

The induced voltage generated in the auxiliary antenna coil 23 is supplied to the receiving amplifier 29, band-pass filter 31, detector 33, low-pass filter 35, and S / H circuit 37 in the same manner as described above.
And is sent to the processing device 40 as a voltage value through the A / D conversion circuit 39 and is compared with a predetermined threshold level. Here, a voltage value equal to or higher than the threshold level is continuously obtained, and the position indicator A Assume that it is determined that the detection device B is within the effective reading area.

On the other hand, the induced voltage generated in the one loop coil is amplified by the receiving amplifier 28, sent to the detector 32 via the band pass filter 30, and detected.
Further, the signal is sent to the processing device 40 as a voltage value through the low-pass filter 34, the S / H circuit 36, and the A / D conversion circuit 38. Thereafter, one loop coil selected by the selection circuit 22 is sequentially switched, and the same operation is repeated, and the voltage value of the induced voltage generated in each of the loop coils 21-1 to 21-4 is transmitted to the processing device 40. Is done.

The voltage value of the induced voltage extracted from each of the loop coils 21-1 to 21-4 depends on the distance between each loop coil and the resonance circuit 11, and the greater the distance, the greater. Therefore, the voltage value of the induced voltage extracted from each of the loop coils 21-1 to 21-4 is determined by the position of the resonance circuit 11,
That is, the induced voltage corresponding to the loop coil closest to the position indicated by the position indicator A is maximized, and gradually decreases as the corresponding loop coil moves away from the indicated position. The voltage value of each of the induced voltages is subjected to arithmetic processing by the processing device 40, and the position where the distribution of the voltage value is maximum, that is, the position indicator A
The coordinate value of the designated position is obtained.

The above-described coordinate detection operation is repeatedly executed, and the coordinate value of the designated position is also updated. When the switch 13 of the position indicator A is operated during the operation, the resonance circuit 11 is operated.
A part of the induced voltage generated in the resonance circuit 11 by the electromagnetic energy given to the rectifying circuit 12 is rectified via the diode 14, and the capacitor 12b of the integrating circuit 12 starts to be charged.

The capacitor 12b is charged until the induced voltage generated in the resonance circuit 11 substantially matches the terminal voltage of the capacitor 12b (however, the voltage drop of the diode 14 is neglected), ie, as described above. During one transmission / reception period of the radio wave, and during the charging period, the resonance circuit 11
The electromagnetic energy stored in the coil 11a decreases
The intensity of the generated radio wave of the frequency fo also decreases. That is, as shown in FIG. 3, during the next reception period in which the switch 13 is turned on, an induced voltage equal to or higher than the predetermined threshold level cannot be obtained in the auxiliary antenna coil 23.

When the processing device 40 detects that an induced voltage of not less than a predetermined threshold level is not obtained in the auxiliary antenna coil 23 during the coordinate detection operation, the processing device 40 causes the auxiliary antenna coil 23 to transmit and receive radio waves again. If an induced voltage equal to or higher than the predetermined threshold level is obtained, it is determined that the switch 13 of the position indicator A has been operated, and if no induced voltage equal to or higher than the predetermined threshold level is obtained continuously, the position indicator A
Is determined to be out of the effective reading area.

If no induced voltage higher than a predetermined threshold level is obtained in the auxiliary antenna coil 23, no effective induced voltage is obtained in the loop coils 21-1 to 21-4. Reset the coordinate detection operation.

As described above, according to the present embodiment, it is only necessary to add a diode and an integrating circuit to the position indicator, and these do not affect the resonance frequency of the resonance circuit. In addition, the adjustment of the resonance frequency is simplified, and it is only necessary to detect a level change at one frequency, so that a switch operation of the position indicator can be identified without requiring a wide frequency range.

FIG. 4 shows another example of the position indicator in the first embodiment. FIG. 3A shows the capacitor 1
According to this configuration, the resonance circuit 1 is connected even when the switch 13 is kept on.
When the energy supplied from the first side runs out, the electric charge charged in the capacitor 12b is discharged. Also,
(b), a two-contact switch 16 is provided in place of the switch 13, and the normally closed contact and the capacitor 1 are provided.
2b is short-circuited with the other end. According to this configuration,
When the operation on the switch 16 is stopped, the capacitor 12b
Is immediately discharged. FIG. 4C shows a two-contact switch 16 provided in place of the switch 13 and a diode 17 connected in the opposite direction to the diode 14 via the normally closed contact. Each time the operation for 16 is repeated, charging and discharging of the capacitor 12b is performed.

FIG. 5 shows a second embodiment of the present invention. Here, an example is shown in which the pen pressure information can be input together with the switch information in the first embodiment. That is, in the figure,
11c is a variable capacitor, 41 is a phase comparator, 42
Is a low-pass filter, 43 is a sample hold (S / H)
A circuit 44 is an analog / digital (A / D) conversion circuit, and 45 is a processing device.

The variable capacitor 11c is a position indicator A
The capacitance value changes according to the pen pressure applied to the coil 11a, and is connected in series with the coil 11a to form a resonance circuit 11 '. Here, the resonance circuit 11 'operates at a phase angle 60 of the frequency fo when no pen pressure is applied.
The phase angle is set to a frequency detected as °, for example, by gradually applying a maximum of 500 g of pen pressure,
It is assumed that it is set so that it can be continuously changed up to 60 °.

The phase comparator 41 is a band pass filter 31
, Ie, the frequency fo component of the induced voltage generated in the auxiliary antenna coil 23 and the AC signal from the oscillator 4 are compared, and the phase difference signal is compared with the low-pass filter 42.
To send to. The low-pass filter 42 has a cutoff frequency sufficiently lower than the frequency fo, converts the output signal of the phase comparator 41 into a DC signal, and sends it to the S / H circuit 43. S /
The H circuit 43 holds the voltage value of the output signal of the low-pass filter 42 at a predetermined timing in accordance with the sampling signal applied from the processing device 40 and sends it to the A / D conversion circuit 44. The A / D conversion circuit 44 converts the output of the S / H circuit 43 from analog to digital, and
Send to 5.

The processing unit 45 calculates the coordinate value of the position indicated by the position indicator A based on the level of the induced voltage corresponding to each of the loop coils 21-1 to 21-4 converted into the digital value. And discriminating whether or not the switch 13 of the position indicator A has been turned on based on a change in the voltage value of the induced voltage of the auxiliary loop coil 23 converted into the digital value, and further detects the phase difference signal converted into the digital value. Pen pressure is detected based on the FIG. 6 shows the processing device 45.
FIG. 2 shows the flow of processing in the first embodiment, except that the pen pressure is detected from the level of the phase difference signal converted into a digital value after the coordinate calculation. It is the same as the one. The auxiliary antenna coil 2
3, the change in the level of the transmission signal and the level of the reception signal
This is the same as the embodiment.

As described above, according to the present embodiment, just as in the first embodiment, it is only necessary to add a diode and an integrating circuit to the position indicator, and these add to the resonance frequency of the resonance circuit. Since there is no influence, the configuration of the position indicator and the adjustment of the resonance frequency are simplified, and only a level change at one frequency need be detected, so that a wide frequency range is not required and the switch operation of the position indicator is performed. Can be identified, and the pen pressure can be simultaneously detected.

In the first and second embodiments, the position is detected in one direction.
A plurality of loop coils similar to -4 are arranged so as to be orthogonal thereto, and a selection circuit similar to the above is provided, and the other circuits are switched to alternately detect their positions, thereby indicating two orthogonal directions. Needless to say, the position can be detected.

FIG. 7 shows another example of the processing flow in the processing apparatus of the first embodiment. Here, transmission and reception of radio waves are repeatedly stopped at a fixed period for a predetermined time, and reception is resumed after transmission is resumed. Only when the level of the applied radio wave is temporarily reduced, it is shown that the switch means is identified as being operated. FIG. 8 shows an example of a transmission signal and a reception signal in the auxiliary antenna coil 23 when the processing shown in FIG. 7 is executed. Note that the above-described processing is similarly applicable to the second embodiment.

In the embodiments described so far, transmission and reception of radio waves are performed alternately. However, the present invention can be applied to an apparatus that performs transmission and reception of radio waves simultaneously.

FIG. 9 shows a third embodiment of the present invention. In this embodiment, in the first embodiment, the loop coils are divided into those for radio wave transmission and those for radio wave reception, and these are provided so as to be orthogonal to each other. An example in which transmission and reception are performed simultaneously will be described. That is, in the figure, 51-1, 51-2, 5
1-3 are loop coils, 52 is a selection circuit, 53 is a synchronous detection circuit, and 54 is a processing device.

The loop coils 51-1 to 51-3 are, for example, loop coils 21-1 to 21-4 arranged in parallel in the x direction.
Are arranged side by side substantially parallel to each other in a direction perpendicular to the direction, ie, the y direction. One end of each of the loop coils 51-1 to 51-3 is connected to the selection circuit 52, and the other end is commonly grounded.

The selection circuit 52 is controlled by the loop coils 51-1 to 5-1 in accordance with a predetermined selection signal applied from the processing unit 54.
One loop coil is sequentially selected from 1-3. The selection circuit 52 is connected only to the current driver 25, and the loop coils 51-1 to 51-3 constitute loop coils for radio wave transmission. Further, the selection circuit 22 includes a receiving amplifier 28
And the loop coils 21-1 to 21-
Reference numeral 4 denotes a loop coil for radio wave reception.

The synchronous detection circuit 53 performs synchronous detection of the induced voltage amplified by the receiving amplifier 28 and extracted by the band-pass filter 30 using an AC signal from the oscillator 24 as a detection signal. The processing device 54 converts the coordinate values of the position indicated by the position indicator A in the x direction and the y direction based on the level of the voltage value of the induced voltage corresponding to each of the loop coils 21-1 to 21-4 converted into the digital value. In addition to the calculation, it is determined whether the switch 13 of the position indicator A has been turned on based on the change in the voltage value of the induced voltage.

FIG. 10 shows a flow of processing in the processing device 54, and FIG. 11 shows an example of a transmission signal and a reception signal. The operation of the device will be described below in accordance with these.

One of the loop coils 51-1 to 51-3 is selected by the selection circuit 52.
It is connected to a current driver 25 to generate a radio wave of frequency fo. At this time, assuming that the position indicator A is within the effective reading area of the position detecting device B, the radio wave excites the resonance circuit 11 and gives electromagnetic energy to it, as in the case of the first embodiment. A radio wave having the same frequency fo is generated from the resonance circuit 11. The radio waves are transmitted through loop coils 21-1 to 21-21.
-4, the one loop coil selected by the selection circuit 22 is excited in reverse, so that an induced voltage having substantially the same frequency as the predetermined frequency fo is generated in the one loop coil.

Here, the loop coils 21-1 to 21-4
Is performed every time one of the loop coils 51-1 to 51-3 is selected, so that the resonance circuit 11 is selected in accordance with the sequential selection of the loop coils 21-1 to 21-4. Of the induced voltage corresponding to the indicated position in the x-direction.

At this time, the induced voltage is detected by the synchronous detection circuit 5.
3, the loop coils 51-1 to 51-1
-3, when the loop coil immediately below the resonance circuit 11 is selected and when the other loop coils are selected, the phases of the induced voltages are inverted. According to the sequential selection of -3, the voltage value of the induced voltage corresponding to the designated position in the y direction of the resonance circuit 11 is obtained.

The voltage values of the respective induced voltages obtained in accordance with the sequential selection of the loop coils 21-1 to 21-4 and the loop coils 51-1 to 51-3 are processed by the processing device 54, and the distribution of the voltage values is maximized. , That is, the coordinate values in the x and y directions of the designated position are obtained.

The above-described coordinate detection operation is repeatedly executed, and the coordinate value of the designated position is also updated. However, if the switch 13 of the position indicator A is operated during the operation, the case of the first embodiment differs from that of the first embodiment. Similarly, a part of the induced voltage generated in the resonance circuit 11 by the electromagnetic energy given to the resonance circuit 11 is rectified through the diode 14 and starts to charge the capacitor 12b of the integration circuit 12.

The charging of the capacitor 12b is performed until the induced voltage generated in the resonance circuit 11 substantially matches the terminal voltage of the capacitor 12b (however, the voltage drop of the diode 14 is neglected). During the charging period,
The electromagnetic energy stored in the resonance circuit 11 decreases,
The intensity of the radio wave of the frequency fo generated from the coil 11a also decreases.

That is, as shown in FIG.
When the is turned on, the induced voltage sharply decreases, and then returns to the original level with a rising characteristic according to the well-known charging characteristic of the CR circuit.

During the coordinate detecting operation, the processing device 54 operates the loop coils 21-1 to 21-4 and the loop coil 51-1.
Of the largest induced voltage among the induced voltages obtained by the sequential selection of ５１51-3, the level change is continuously detected, and the level rapidly decreases,
Thereafter, if the level returns to the original level with a predetermined rising characteristic, it is determined that the switch 13 of the position indicator A has been operated. If the level has not returned to the original level, it is determined that the position indicator A has moved out of the effective reading area. . When the level change described above occurs, the loop coils 21-1 to 21-
4 cannot obtain an effective induced voltage,
Resets the coordinate detection operation.

FIG. 11 shows the transmission signal and the reception signal in a state where the positions of the loop coils and the position indicator on the transmission side and the reception side are fixed in order to make it easy to understand the level change accompanying the switch operation.

FIG. 12 shows that the transmission and reception of radio waves are performed simultaneously, the transmission and reception of the radio waves are repeatedly stopped at a predetermined cycle for a predetermined time, and the level of the received radio waves after the resumption of transmission has a predetermined rising characteristic. 11 shows an example of a transmission signal and a reception signal similar to FIG. 11 when the switch means is identified as being operated when
Also in this case, by applying the processing shown in FIG. 7 to the third embodiment, the position indicated by the position indicator in the x direction and y
In addition to calculating the coordinate value of the direction, it is possible to identify whether or not the position indicator is switched on based on the change in the voltage value of the induced voltage.

[0065]

As described above, according to the present invention, it is only necessary to add a diode and an integrating circuit to the position indicator, and these do not affect the resonance frequency of the resonance circuit. The configuration of the device and the adjustment of the resonance frequency are simplified, and since it is only necessary to detect a level change at one frequency, a wide frequency range is not required.
The switch operation of the position indicator can be identified.

Further, according to the present invention, it is only necessary to add a diode and an integrating circuit to the position indicator, and these do not affect the resonance frequency of the resonance circuit. Adjustment of frequency becomes easy,
Since only a level change for one frequency needs to be detected, a wide frequency range is not required, the switch operation of the position indicator can be identified, and the pen pressure can be simultaneously detected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a position detection device of the present invention.

FIG. 2 is a flowchart of processing in the processing apparatus of the first embodiment.

FIG. 3 is a diagram showing an example of a transmission signal and a reception signal in the auxiliary antenna coil of the first embodiment.

FIG. 4 is a configuration diagram showing another example of the position indicator in the first embodiment.

FIG. 5 is a configuration diagram showing a second embodiment of the position detection device of the present invention.

FIG. 6 is a flowchart of processing in a processing apparatus according to a second embodiment.

FIG. 7 is a diagram showing another example of the processing flow in the processing apparatus of the first embodiment.

FIG. 8 is a diagram illustrating another example of a transmission signal and a reception signal in the auxiliary antenna coil of the first embodiment.

FIG. 9 is a configuration diagram showing a third embodiment of the position detection device of the present invention.

FIG. 10 is a flowchart of processing in the processing apparatus of the third embodiment.

FIG. 11 is a diagram illustrating an example of a transmission signal and a reception signal according to the third embodiment.

FIG. 12 is a diagram showing still another example of a transmission signal and a reception signal in the present invention.

[Explanation of symbols]

11, 11 '... resonance circuit, 11a ... coil, 11b ... capacitor, 11c ... variable capacitance capacitor, 12 ... integration circuit, 12a ... resistor, 12b ... capacitor, 13, 16 ...
Switch, 14, 17 ... Diode, 21-1 to 21-
4, 51-1 to 51-3 ... loop coil, 22, 52 ...
Selection circuit, 23: auxiliary antenna coil, 24: oscillator,
25 current driver, 26, 27 switching connection circuit, 2
8, 29: receiving amplifier, 30, 31, band-pass filter, 32, 33: detector, 34, 35, 42: low-pass filter, 36, 37, 43: sample and hold circuit, 3
8, 39, 44 ... analog-digital conversion circuit, 4
0, 45, 54 ... processing device, 41 ... phase comparator, 53 ...
Synchronous detection circuit.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 3/03

Claims (12)

(57) [Claims] 1. A position detecting device for detecting an indicated position of a position indicator having a resonance circuit including at least a coil and a capacitor, wherein the position detection device is connected in parallel with the resonance circuit via a switch and a rectifier circuit connected in series with each other. At least an integration circuit including a capacitor is connected, a radio wave transmitting unit for transmitting a radio wave for exciting the resonance circuit, a radio wave reception unit for receiving a radio wave generated from the resonance circuit, and a radio wave reception unit receiving the radio wave. A position detecting device comprising: a state identifying unit that detects a temporary change in the level of a radio wave and identifies that the switch unit has been operated. 2. A position detecting device for detecting a position indicated by a position indicator having a resonance circuit including at least a coil and a capacitor, the resonance frequency of which changes according to writing pressure, wherein the position detection device is connected in series with each other in parallel with the resonance circuit. A radio wave transmitting unit for transmitting a radio wave for exciting the resonance circuit, and a radio wave receiving unit for receiving a radio wave generated from the resonance circuit, while connecting an integrating circuit including at least a capacitor via the switch unit and the rectifier circuit thus configured. A first state identification unit that detects a temporary change in the level of a radio wave received by the radio wave reception unit and identifies that the switch unit has been operated; and a radio wave transmitted from the radio wave transmission unit. Phase difference detecting means for detecting a phase difference from a radio wave received by the radio wave receiving means; and a pen pressure detecting means for detecting pen pressure from the phase difference detected by the phase difference detecting means. 2. A position detecting device comprising: (2) a state identification unit. 3. The method according to claim 1, wherein the transmission and reception of the radio waves are performed alternately and continuously, and only when the level of the received radio waves temporarily decreases, it is determined that the switch means has been operated. The position detection device according to claim 1. 4. When the transmission and reception of a radio wave are alternately performed, the transmission and reception of the radio wave are repeatedly stopped at a predetermined period for a predetermined time, and the level of the received radio wave is temporarily reduced after the transmission is resumed. 3. The apparatus according to claim 1, wherein only the switch means is operated.
The position detecting device as described in the above. 5. The transmission and reception of radio waves are performed simultaneously and continuously, and when the level of the received radio waves temporarily decreases and then returns to the original level with a predetermined rising characteristic, the switch means is operated. The position detecting device according to claim 1, wherein the position is detected. 6. When the transmission and reception of radio waves are performed simultaneously and the transmission and reception of the radio waves are repeatedly stopped for a predetermined period of time for a predetermined period, and the level of the radio waves received after resumption of transmission shows a predetermined rising characteristic, 3. The position detecting device according to claim 1, wherein the switch means is identified as being operated. 7. A resonance circuit including at least a coil and a capacitor, and an integration circuit including at least a capacitor,
A position indicator connected in parallel via switch means and a rectifier circuit connected in series to each other; a plurality of loop coils arranged in parallel in the position detection direction; and an auxiliary antenna provided near the plurality of loop coils. A coil; a selecting means for sequentially selecting one loop coil from the plurality of loop coils; a first level detecting means for detecting a level of an induced voltage generated in the selected loop coil; AC signal generating means for generating an AC signal for generating a radio wave for exciting the resonance circuit; second level detecting means for detecting a level of an induced voltage generated in the auxiliary antenna coil; AC signal generating means and second
Switching connection means for switching and connecting the level detection means, coordinate value calculation means for obtaining coordinate values of the position indicated by the position indicator based on the level of each induced voltage detected by the first level detection means, A position detecting device for detecting a temporary decrease in the level of the induced voltage detected by the second level detecting means and identifying the operation of the switch means. . 8. A resonance circuit including at least a coil and a capacitor, and an integration circuit including at least a capacitor,
A position indicator connected in parallel via switch means and a rectifier circuit connected in series to each other; a plurality of loop coils arranged in parallel in the position detection direction; and an auxiliary antenna provided near the plurality of loop coils. A coil; a selecting means for sequentially selecting one loop coil from the plurality of loop coils; a first level detecting means for detecting a level of an induced voltage generated in the selected loop coil; AC signal generating means for generating an AC signal for generating a radio wave for exciting the resonance circuit; second level detecting means for detecting a level of an induced voltage generated in the auxiliary antenna coil; and Phase difference detecting means for detecting a phase difference between the generated AC signal and the induced voltage generated in the auxiliary antenna coil; AC signal generating means and the second
Switching connection means for switching between the level detection means and the phase difference detection means, and coordinates for obtaining the coordinate value of the position indicated by the position pointer based on the level of each induced voltage detected by the first level detection means. Value calculation means, first state identification means for detecting a temporary decrease in the level of the induced voltage detected by the second level detection means, and identifying that the switch means has been operated; A position detecting device comprising: a second state identifying unit that detects pen pressure from a phase difference detected by a phase difference detecting unit. 9. An auxiliary antenna coil by switching connection means.
Repeat predetermined time transmission and reception of radio waves at a constant period is detected hand stage you stop, temporary reduction in the level of the detected induced voltage after resuming transmission at the second level detection means in the switch 9. The position detecting device according to claim 7, further comprising: state identification means for identifying that the means has been operated. 10. A radio wave transmitted from a position detecting device having a resonance circuit including at least a coil and a capacitor.
Based on at least the induced voltage corresponding to the indicated position
In a position indicator generated on the position detecting device side, the resonance circuit and an integration circuit including at least a capacitor are connected in parallel via switch means and a rectifier circuit connected in series to each other. Indicator. 11. has a resonant circuit the resonant frequency changes according to contain writing pressure at least a coil and a capacitor, position
At least based on the radio waves transmitted from the
The induced voltage corresponding to the indicated position and pen pressure is
In the position indicator generated on the installation side, the resonance circuit and an integration circuit including at least a capacitor are connected in parallel via switch means and a rectifier circuit connected in series to each other. . 12. The position pointing device according to claim 10, wherein a resistor is connected in parallel to a capacitor of the integration circuit.