JP2513681B2 - Coordinate input device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coordinate input device capable of detecting the state of a cordless position pointing device.

(Prior Art) The applicant of the present application has filed Japanese Patent Application No. 59-32244 “position detecting device” (see Japanese Patent Application Laid-Open No. 60-176133) or Japanese Patent Application No.
In the "Coordinate position detecting device" of 238532 (see Japanese Patent Laid-Open No. 60-129616), if the position indicator is cordless and within a predetermined interval (about 2 to 3 cm), the tablet and the position indicator are We proposed a device that can input coordinates even if the distance is away.

All of the coordinate input devices described above are designed to detect the position specified by the position indicator having a steady magnetic bias source such as a permanent magnet within the coordinate input range of the tablet. For that purpose, it was not necessary to exchange signals such as radio waves and optical signals between the position indicator and the position detection circuit.

(Problems to be Solved by the Invention) However, in actual use, the state of the position indicator (hereinafter, referred to as a pen-down state) in which the coordinate position to be input on the tablet is designated is set in the position detection circuit or its upper device. In order to transmit, the position indicator is provided with a switch means, a transmitter for ultrasonic waves or infrared rays, a signal generation circuit, a battery, etc., and a timing signal based on the turning on (or off) of the switch means at the time of pen down is transmitted by the ultrasonic wave. Therefore, the structure of the position indicator becomes complicated, the size and weight of the position indicator become large, and the batteries must be replaced and charged frequently. However, there is a problem that the operability of is deteriorated to some extent.

It is an object of the present invention to provide a coordinate input device capable of detecting the operating state of a cordless position indicator without degrading the operability of the position indicator.

It is another object of the present invention to provide a coordinate input device capable of detecting the height as well as the operating state of the cordless position indicator without degrading the operability of the position indicator.

(Means for Solving the Problems) In order to achieve the above object, as a first invention, a first tuning circuit that is constantly closed, and the first tuning circuit that is configured by a switch operation of an operator are provided. A coordinate input device for detecting switch operation of a position indicator having a different tuning frequency and notifying a switch operation to a tablet, wherein the first and second tuning circuits can be tuned. Radio wave transmitting means for transmitting a radio wave, radio wave receiving means for receiving a radio wave resulting from the tuning reflected from the first or second tuning circuit of the position indicator, and a level of the received radio wave within a predetermined range And a phase difference detecting means for detecting a phase difference between the radio wave transmitted from the radio wave transmitting means and the radio wave received by the radio wave receiving means and amplified by the amplifying means. Phase difference A coordinate input device is proposed which detects a switch operation of a position indicator based on a phase difference between radio waves detected by a detection means.

In order to achieve the above object, as a second invention,
Position having a first tuning circuit that is steadily closed and a second tuning circuit that is configured by an operator's switch operation and has a tuning frequency different from that of the first tuning circuit to notify the tablet of the switch operation A coordinate input device for detecting a switch operation of an indicator, which is radio wave transmitting means for transmitting an electric wave capable of being tuned by the first and second tuning circuits, and the first or second tuning circuit of the position indicator. A radio wave receiving means for receiving the radio wave due to the tuning reflected from the radio wave, and a gain for amplifying the received radio wave with a gain according to a gain control signal so that the level of the amplified radio wave becomes a value within a predetermined range. Variable gain amplifying means for changing the control signal to change the gain,
A radio wave detected by the phase difference detecting means, which has a phase difference detecting means for detecting a phase difference between the radio wave transmitted from the radio wave transmitting means and the radio wave received by the radio wave receiving means and amplified by the variable gain amplifying means. A coordinate input device is proposed which detects the switch operation of the position indicator from the phase difference of the above and also detects the height of the position indicator from the gain control signal.

(Operation) According to the first invention, the radio wave transmitted from the radio wave transmitting means excites the first or second tuning circuit of the position indicator, and a similar radio wave is generated from the first or second tuning circuit. Generate, that is, reflect. The radio wave reflected by the first or second tuning circuit is received by the radio wave receiving means. At this time, the level of the radio wave received by the radio wave receiving means indicates a value corresponding to the distance between the position indicator and the radio wave transmitting means and the radio wave receiving means. Shows a small value when they are separated from each other, but the small value is amplified to a value within a predetermined range by the amplification means, and the phase difference between the amplified radio wave and the radio wave transmitted from the radio wave transmission means is the phase difference detection means. Is detected, and whether it is the first tuning circuit or the second tuning circuit is detected, and thereby the operating state of the position indicator is detected.

According to the second invention, the level of the radio wave received by the radio wave receiving means indicates a distance between the position indicator and the radio wave transmitting means and the radio wave receiving means, that is, a value corresponding to the height of the position indicator. , A radio wave having a value corresponding to the height of the position indicator is amplified to a value within a predetermined range by a variable gain amplifying means controlled by a gain control signal from the gain control means, and further the radio wave and the radio wave after the amplification are transmitted. The phase difference with the radio wave transmitted from the means is detected by the phase difference detecting means, which of the first tuning circuit and the second tuning circuit is detected, thereby detecting the operation state of the position indicator and gain. The height of the position indicator is detected from the gain control signal sent from the control means to the variable gain amplification means.

(Embodiment) FIG. 1 shows an embodiment of the coordinate input device of the present invention, in which 1 is a tablet, 2 is a position indicator, 3 is a position detection circuit, and 4 is a timing control circuit.

The tablet 1 has a tablet body 12 and an antenna coil 13 mounted on a non-magnetic metal casing 11. The tablet body 12 is connected to the position detection circuit 3, and the antenna coil 13 is connected to the timing control circuit 4. Has been done.

The tablet body 12 is driven by the position detection circuit 3 and constitutes a detection unit for detecting the position designated by the position indicator 2, and the tablet body 12 is housed in the housing 11 substantially at the center thereof. The frame 14 drawn on the top panel 11a of the housing 11 indicates the coordinate input range.

As the tablet body 12 and the position detection circuit 3,
As long as the position indicator is cordless and within a predetermined distance, any device can be used as long as the device can input coordinates even if the tablet and the position indicator are separated, but the application of the applicant of the present application described above is possible. It is preferable to use the device according to the above.

The antenna coil 13 includes an insulating coated conductor, the coordinate input range of the tablet body 12, that is, the casing 11 around the frame 14.
It is arranged on the surface of the upper panel 11a. Although it is shown as a coil of one turn in the drawing, it is actually composed of a coil of several turns.

The position indicator 2 is a stylus pen (hereinafter referred to as a pen) corresponding to the device according to the above-mentioned applicant's application, and includes a magnetic generator for specifying a position, such as a magnet 21 and a tuning circuit 22. Built-in.

FIG. 2 shows the detailed structure of the pen 2. Inside the pen shaft 23 made of a non-metallic material such as synthetic resin, a writing core 24 such as a ballpoint pen and the core 24 are drawn from the tip end thereof. A bar magnet 21 having a through hole capable of slidably accommodating therein, a coil spring 25, a switch 221, a coil 222 with a core, and a capacitor.
A tuning circuit 22 composed of 223 and 224 is integrally combined and built in, and a cap 26 is attached to the rear end thereof.

The coil 222 and the capacitor 223 are connected to each other in series as shown in FIG. 3 so as to form a well-known resonant circuit, and the numerical values of the coil 222 and the capacitor 223 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
224 is connected in parallel to both ends of the capacitor 223 via the switch 221, and when the switch 221 is turned on, delays the phase of the current in the above-mentioned resonant circuit by a certain angle and delays the phase of the reception signal described later by a predetermined angle. Act. It should be noted that the switch 221 uses the tip of the core body 24 to detect the position detecting unit
When it is pushed into the pen shaft 23 by pressing it against the input surface of the above, the rear end of the pen shaft is pressed through the coil spring 25 and turned on.

Here, the above-mentioned circuit composed of the coil 222 and the capacitor 223 constitutes a first tuning circuit which is normally closed, and the circuit composed of the switch 221, the coil 222 and the capacitors 223, 224 is constituted by the switch operation of the operator. A second tuning circuit that is different in tuning frequency from the first tuning circuit and notifies the tablet of the switch operation is provided (note that the concept of "steady" described above means that "the operator does not perform a switch operation". "State" is also included.)

FIG. 3 shows the tuning circuit 22 and the timing control circuit 4
2 shows a detailed configuration of the above. In the figure, 401 is a control circuit, 402 is a timing circuit, 403 is a drive circuit, and 404.
Is a transmission / reception switching circuit, 405 is an amplifier, 406 is a reception timing switching circuit, 407 is a variable gain amplifier (PGA), 408 is a bandpass filter (BPF), 409 is a detector, and 410 and 411 are phase detectors (PS).
D), 412, 413 and 414 are low pass filters (LPF).

Here, the above-mentioned antenna coil 13 and timing circuit
402, the drive circuit 403, and the transmission / reception switching circuit 404 constitute a radio wave transmitting means, and the antenna coil 13 and the transmission / reception switching circuit 40 are included.
4, the amplifier 405, the reception timing switching circuit 406 and the band filter 408 constitute a radio wave receiving means, and the variable gain amplifier 407, the detector 409, the low pass filter 412 and the control circuit 401.
Constitutes the amplifying means, and the phase detectors 410, 411 and the low-pass filters 413, 414 constitute the phase difference detecting means.

FIG. 4 is a signal waveform diagram in each part of FIG. The operation will be described in detail below.

The control circuit 401 is configured by a well-known microprocessor or the like, controls the timing circuit 402, converts the output values from the low-pass filters 412 to 414 into analog / digital (A / D), and outputs the output value of the low-pass filter 412. Variable gain amplifier so that the corresponding digital value is within a predetermined range
407, and also identifies the state of the switch 221 from the digital value corresponding to the output values of the low pass filters 413, 414,
This is sent to the position detection circuit 3.

The timing circuit 402 includes a rectangular wave signal A having a predetermined frequency f0 and a signal A ′ obtained by delaying the phase of the rectangular wave signal A by a predetermined angle.
(Not shown), a transmission / reception switching signal B and a reception timing signal C having a predetermined frequency fk are generated. The rectangular wave signal A is sent to the phase detector 410, converted into a sine wave signal by a low-pass filter (not shown) and sent to the drive circuit 403, and the rectangular wave signal A ′ is sent to the phase detector 411. The transmission / reception switching signal B is transmitted to the transmission / reception switching circuit 404, and the reception timing signal C is further transmitted to the reception timing switching circuit 406.

The sine wave signal sent to the drive circuit 403 is converted into a balanced signal and further sent to the transmission / reception switching circuit 404. The transmission / reception switching circuit 404, based on the transmission / reception switching signal B, drives the circuit 403.
And either the amplifier 405 or the amplifier 405 alternately
Since the connection is switched to 3, the antenna coil 13 has time T
A signal D that outputs or does not output a sine wave signal having a frequency f0 is input every (= 1/2 fk), and the signal D is transmitted as a radio wave from the antenna coil 13.

At this time, within the coordinate input range 14 of the tablet 1,
When the pen 2 is held in a substantially upright state, that is, in a used state, the radio wave excites the coil 222 of the input pen 2 and causes the tuning circuit 22 to generate an induced voltage E synchronized with the signal D.

After that, the antenna coil 13 is switched to the amplifier 405 side by the transmission / reception switching circuit 404, that is, when the reception period starts,
The radio wave from the antenna coil 13 disappears immediately, but the induced voltage E gradually attenuates according to the loss in the tuning circuit 22.

On the other hand, the current flowing through the tuning circuit 22 based on the induced voltage E causes the coil 222 to emit a radio wave. Since the radio wave excites the antenna coil 13 in the opposite direction,
An induction voltage due to the radio wave from the coil 222 is generated in the coil 13. The induced voltage is applied to the transmission / reception switching circuit 404 only during the reception period.
The signal is sent to the amplifier 405, amplified and becomes the received signal F, which is further sent to the reception timing switching circuit 406.

The reception timing switching circuit 406 receives a 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 a high (H) level, and outputs a 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 407.

As shown in FIG. 5, the variable gain amplifier 407 includes a plurality of, here eight, resistors R for gain control, a well-known multiplexer MPX, and an amplifier AMP, and a gain control signal sent from the control circuit 401. Accordingly, 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 407 is controlled so that the gain becomes the smallest, that is, the lowermost terminal is selected in the multiplexer MPX, and the signal is gained at the gain (1/8 of the maximum gain) at this time. G is amplified and sent to the bandpass filter 408 as a signal H (the same as the signal G except for the amplitude) (note that the signals F, G, and H are shown as one waveform in FIG. 4, but actually The amplitude of signal H is different from that of signal G or F).

The band-pass filter 408 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 band-pass filter 408 and converged, the signal is sent to the detector 409 and the phase detectors 410 and 411.

The signal I input to the detector 409 is detected and rectified to be a signal J, and then has a voltage value Vk corresponding to approximately 1/2 of the amplitude i by a low pass filter 412 having a sufficiently low cutoff frequency. It is converted into a DC signal K and sent to the control circuit 401.

The control circuit 401 A / D-converts the DC signal K into a digital value, for example, Dk, and then sets the digital value Dk in a predetermined range, for example, digital values Da and Db (Da> Db).
It is determined whether the value is between or.

The digital values Da and Db are the tuning circuit of the pen 2 when the gain in the variable gain amplifier 407 is the smallest.
It is set to a value including a digital value obtained when the electromagnetic coupling between the antenna 22 and the antenna coil 13 is strongest, that is, when the tip of the core body 24 of the pen 2 is in contact with the top panel 11a of the tablet 1. .

At this time, the control circuit 401 determines that the digital value Dk is not a value between the digital values Da and Db.
When it is determined that it is Db or less, the variable gain amplifier 40 is controlled so that the digital value Dk becomes a value between the digital values Da and Db.
Change the gain control signal to the multiplexer MPX of 7. Therefore, the amplitude i of the output I of the bandpass filter 408 is always a fixed value or more, and the signal I having the amplitude i of the fixed value or more is sent to the phase detectors 410 and 411.

On the other hand, the rectangular wave signal A is input to the phase detector 410 as a detection signal. At this time, the switch 221 is off and the phase of the signal I substantially matches the phase of the rectangular wave signal A. Then, a signal obtained by inverting the signal I to the positive side (substantially the same as the signal J) is output. This signal is a DC signal (substantially the same as the signal K) having a voltage value corresponding to approximately 1/2 of the amplitude i in the low pass filter 413 similar to the above.
Is converted to the control circuit 401 and transmitted to the control circuit 401.

Further, although the rectangular wave signal A'is input to the phase detector 411 as a detection signal, as described above, the switch 221
Is off and the phase of the signal I (substantially the same as the phase of the received signal F) 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 obtained. Output. This signal is converted into a DC signal by the same low-pass filter 414 as described above and sent to the control circuit 401, but since the output signal of the phase detector 411 has components on the positive side and the negative side here, it is a low-pass filter. The voltage value of the output of 414 is considerably smaller than the voltage value of the output of the low-pass filter 413.

When the switch 221 of the pen 2 is turned on, the phase of the current flowing through the tuning circuit 22 is delayed by a certain angle with respect to the induced voltage E, and the phase of the received signal F is delayed by a predetermined angle, that is, the phase of the rectangular wave signal A '. Will almost agree with. Therefore,
The output I of the bandpass filter 408 at this time is converted into a signal having components on the positive side and the negative side by the phase detector 410, and the output of the low-pass filter 413 is the output of the low-pass filter 414 when the above-mentioned switch 221 is off. However, the output of the low-pass filter 414 has a predetermined voltage value corresponding to approximately 1/2 of the amplitude i as in the above. Become a signal.

In this way, when the switch 221 is off, the low pass filter 4
A predetermined voltage value is obtained at the output of 13 and switch 221
When is on, a predetermined voltage value is obtained at the output of the low-pass filter 414, so the low-pass filter 4 in the control circuit 401 is
By monitoring the output values of 13 and 414, the switch 221
Is detected as being off or on.

As described above, the amplitude of the output of the band-pass filter 408 is kept substantially constant even if the tablet 1 and the pen 2 are slightly apart from each other, so that a thick object, such as a book, is placed on the panel upper surface 11a of the tablet 1. It is possible to accurately identify whether the switch 221 in the tuning circuit 22 is on or off even when the position is placed and the coordinates are input using the pen 2 from above.

The information indicating the on (or off) state of the switch 221 identified here is, for example, information designating a value to be actually input among the coordinate values detected by the tablet 1 and the position detection circuit 3. Used as.

The output value of the low-pass filter 412 corresponds to the strength of electromagnetic coupling between the pen 2 and the tablet 1, and in this case, the distance between the pen 2 and the tablet 1, that is, the pen. 2 is a value almost proportional to the height on the tablet 1. Therefore, the position detection circuit uses the digital value obtained by A / D converting the output value of the low-pass filter 412 or the gain control signal of the control circuit 401 for controlling the variable gain amplifier 407 as the information indicating the height of the pen 2 on the tablet 1. 3 or its upper device.

(Effect of the Invention) As described above, according to the first invention, the first tuning circuit which is normally closed and the tuning frequency which is different from that of the first tuning circuit which is configured by the switch operation of the operator. Radio waves are transmitted / received by the radio wave transmitting means and the radio wave receiving means to / from a position indicator having a second tuning circuit for notifying the tablet of the switch operation, and the level of the received radio wave becomes a value within a predetermined range. Whether the first or second tuning circuit detects the phase difference between the radio wave transmitted from the radio wave transmitting means and the radio wave received by the radio wave receiving means and amplified by the phase difference detecting means. Detect
Since the operation state for the position indicator is detected from the result of this detection, it is possible to always obtain a reception signal of a constant level even if the position indicator is slightly apart from the radio wave transmitting means and the radio wave receiving means. Therefore, even when a thick object such as a book is placed on the upper surface of the device and coordinates are input from the top using the position indicator, the operation state of the position indicator can be accurately detected. Also,
The position indicator only needs to be provided with a tuning circuit including a coil and a capacitor, and does not require a complicated signal generating circuit or a battery as in the prior art, so that the position indicator with extremely good operability can be provided.

According to the second aspect of the invention, the first tuning circuit that is normally closed and the tuning frequency that is different from the first tuning circuit that is configured by the switch operation of the operator and notifies the tablet of the switch operation. A variable gain amplifying means for controlling the gain of the received radio wave by a gain control signal from the gain control means. Is detected by the phase difference detecting means by detecting the phase difference between the electric wave emitted from the electric wave transmitting means and the electric wave received by the electric wave receiving means and amplified by the phase difference detecting means. However, since the operation state for the position indicator is detected from the result of this detection and the height of the position indicator is detected from the gain control signal, the operation state for the position indicator is detected. In addition, the height of the position indicator can be detected, and the position indicator only needs to be provided with a tuning circuit including a coil and a capacitor, and a complicated signal generating circuit, battery, etc. as in the past are not required. Therefore, there is an advantage that a position indicator having extremely good operability can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a coordinate input device of the present invention, FIG. 2 is a sectional view of a stylus pen, FIG. 3 is a detailed configuration diagram of a pen tuning circuit and a timing control circuit, and FIG. Is a signal waveform diagram of each part of FIG. 3, and FIG. 5 is a diagram showing details of the variable gain amplifier. 1 ... Tablet, 2 ... Stylus pen, 3 ... Position detection circuit, 4 ... Timing control circuit, 13 ... Antenna coil, 14
… Coordinate input range, 22… Tuning circuit.

Claims (10)

(57) [Claims] 1. A first tuning circuit which is normally closed, and a second tuning which is configured by an operator's switch operation and has a tuning frequency different from that of the first tuning circuit to notify the tablet of the switch operation. A coordinate input device for detecting a switch operation of a position indicator having a circuit, and a radio wave transmitting unit for transmitting a radio wave that the first and second tuning circuits can tune with each other; Radio wave receiving means for receiving the radio wave caused by the tuning reflected from the second tuning circuit, amplifying means for amplifying the level of the received radio wave to a value within a predetermined range, and transmitting from the radio wave transmitting means The phase difference between the electric wave received by the electric wave receiving means and the electric wave received by the electric wave receiving means and amplified by the amplifying means, and the phase difference of the position indicator from the phase difference of the electric wave detected by the phase difference detecting means. Position detecting device being characterized in that none to detect switch operations. 2. The coordinate input device according to claim 1, wherein the radio wave transmitting means and the radio wave receiving means are operated alternately. 3. The coordinate input device according to claim 2, wherein the coil forming the electric wave transmitting means and the coil forming the electric wave receiving means are used in common. 4. The coordinate input device according to claim 1, wherein a magnet for generating a stationary magnetic field is used as the position indicating means. 5. The coordinate input device according to claim 1, wherein the switch-operated state is a pen-down state. 6. A first tuning circuit which is normally closed, and a second tuning which is constituted by a switch operation of an operator and has a tuning frequency different from that of the first tuning circuit and which notifies the tablet of the switch operation. A coordinate input device for detecting a switch operation of a position indicator having a circuit, and a radio wave transmitting unit for transmitting a radio wave that the first and second tuning circuits can tune with each other; Radio wave receiving means for receiving the radio wave caused by the tuning reflected from the second tuning circuit, amplifying the received radio wave with a gain according to a gain control signal, and the level of the amplified radio wave is within a predetermined range. The gain variable amplification means for changing the gain control signal to change the gain so that the phase difference between the radio wave transmitted from the radio wave transmission means and the radio wave received by the radio wave reception means and amplified by the gain variable amplification means is detected. And a phase difference detecting means for outputting, detecting the switch operation of the position indicator from the phase difference of the radio waves detected by the phase difference detecting means, and detecting the height of the position indicator from the gain control signal. A position detection device characterized in that 7. The coordinate input device according to claim 6, wherein the radio wave transmitting means and the radio wave receiving means are operated alternately. 8. The coordinate input device according to claim 7, wherein the coil forming the electric wave transmitting means and the coil forming the electric wave receiving means are used in common. 9. The coordinate input device according to claim 6, wherein a magnet for generating a stationary magnetic field is used as the position indicating means. 10. A pen down state when the switch is operated, according to claims 6 to 9.
A coordinate input device according to any one of paragraphs.