JPH07109575B2 - Position indicator status detection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for detecting the state of a position indicator in a coordinate input device.

(Prior Art) Conventionally, in a coordinate input device, a position indicator has been used as a method of detecting a use state (hereinafter, referred to as a pen-down state) of a position indicator that specifies only a coordinate position to be input on a tablet. A switch means is provided, the switch means is turned on (or off) only when the pen is down, and a timing signal based on the on (or off) of the switch means,
Some have been configured to send to a position detection circuit via a cord or using ultrasonic waves or infrared rays.

(Problems to be solved by the invention) However, in the case where a timing signal is sent from a position indicator using a code, the code deteriorates the operability of the position indicator, and the timing signal is generated using ultrasonic waves or infrared rays. However, in the case of a device that sends a position indicator, the position indicator itself must be provided with these transmitters, signal generation circuits, batteries, etc., which complicates the configuration and makes it large and heavy, which deteriorates the operability of the position indicator. There was a problem to do.

The present invention is a system capable of detecting whether the position indicator is held at a predetermined angle or more with respect to the tablet in the pen axis direction without deteriorating the operability of the position indicator and detecting whether the position indicator is in use. The purpose is to provide.

(Means for Solving Problems) In the present invention, in order to solve the above problems, it is detected whether a pen-type position indicator is held with respect to the tablet of the coordinate input device at a pen axis direction at an angle of a predetermined value or more. In addition, a pen-type position indicator includes a coil and a capacitor whose axial direction substantially coincides with the pen axial direction of the position indicator. Further, by changing any one of these values in accordance with the use condition, a synchronizing circuit is provided which transmits a radio wave in response to an external signal at substantially the same frequency and with a change in phase. Radio waves that have almost the same frequency as the tuning frequency and that can cross only the coil whose axial direction forms an angle greater than a predetermined angle are transmitted to the tablet and are transmitted by the radio wave detection means. Receiving, detecting that the level of the received radio wave is above a certain level and detecting that the pen-type position indicator is held at an angle of the pen axis relative to the tablet at a predetermined angle or more, A state detecting method of a position indicator is proposed which detects a change in the phase of the received radio wave with respect to the transmitted radio wave to detect that the position indicator is in a use state.

(Operation) According to the present invention, when the pen-type position indicator is held with respect to the tablet so that the pen axis direction is at a predetermined angle or more, the coil of the tuning circuit excites the radio wave emitted from the radio wave generating means. And generate an induced voltage in the tuning circuit. The induced voltage radiates radio waves from the coil of the tuning circuit.
The transmitted electric wave is received by the electric wave detecting means,
Since the level becomes a certain level or higher, it is detected that the pen type position indicator is held with respect to the tablet at an angle of the pen axis at a predetermined angle or more. Also, when the position indicator is in use, the phase of the radio wave transmitted from the tuning circuit and received by the radio wave detection means changes with respect to the radio wave emitted from the radio wave generation means, so the position indicator is in use. Is detected.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 1 is a tablet, 2 is a phase indicator (hereinafter referred to as an input pen), 3 is a position detection circuit, and 4 is timing. It is a control circuit.

The tablet 1 has a housing 11 made of synthetic resin and a tablet body.
The tablet main body 12 is connected to the position detection circuit 3, and the antenna coil 13 is connected to the timing control circuit 4.

The tablet body 12 constitutes a detection unit which is driven by the position detection circuit 3 to detect the position designated by the input pen 2, and the tablet body 12 is arranged at substantially the center of the housing 11. The frame 14 drawn on the top panel 11a of the housing 11 indicates the coordinate input range.

The tablet body 12 and the position detection circuit 3 are, for example, the "coordinate position detection device" of Japanese Patent Application No. 58-238532 filed by the applicant of the present application (see Japanese Patent Laid-Open No. 60-129616).
Alternatively, the "position detecting device" of Japanese Patent Application No. 59-33083 (see JP-A-60-176134) can be used. In the former case, a large number of magnetostrictive transmission media which are parallel to the surface of the tablet body 12 and orthogonal to each other are arranged, and magnetostrictive vibrations are propagated periodically from one end to the other end of the input pen 2. When is approached, the position detection circuit 3 detects the XY coordinates from the propagation time up to that location by utilizing the fact that the magnetostrictive vibration increases at that location by the bar magnet provided on this location. In the latter case, each magnetic substance arranged orthogonally is excited by an alternating current and the induced voltage is taken out by each detection coil, and when a similar input pen approaches, the magnetic permeability of the magnetic substance is locally changed and induced. XY coordinates are detected by utilizing the change in voltage.

The antenna coil 13 is configured by disposing a conductive wire coated with an insulating coating such as vinyl chloride around the coordinate input range of the tablet body 12, here, on the back surface of the top panel 11a of the casing 11 around the frame 14. It is a thing. It should be noted that the illustrated example has one turn, but it may have a plurality of turns if necessary.

The input pen 2 is a magnetic generator for specifying a position, for example, a bar magnet.
21 and a tuning circuit 22 including a coil and a capacitor.

FIG. 2 shows a detailed structure of the input pen 2. A core body 24 such as a ballpoint pen and the core body 24 are slidably housed inside a pen shaft 23 made of a non-metallic material such as synthetic resin. A bar magnet 21 having a through hole that can be used, a coil spring 25, and
A tuning circuit 22 including a coil 222 containing a core 221, such as a ferrite core, a first capacitor 223a, and a variable capacitor 224a for fine adjustment, and a second capacitor 223b connected in parallel with the first capacitor 223a and a fine capacitor. A variable capacitor 224b for adjustment and a switch 225 for turning on / off the connection of the capacitors 223b and 224b are integrally combined and built in, and a cap 26 is attached to the rear end thereof.

The switch 225 is configured such that when the core body 24 is pushed into the pen shaft 23 by pushing the tip end of the core body 24 against the tablet surface, the switch body 225 is pushed by the rear end of the core body 24 via the coil spring 25 and turned on.

When the switch 225 is off, the resonance circuit 22 is in phase with the radio wave transmitted from the antenna coil 13 and resonates (tunes) to that frequency, and when the switch 225 is on, it resonates with a phase difference of 180 °. It is adjusted and set accordingly. By the setting of the resonance circuit 22, the selectivity Q = R /
(Ω0L) (where ω0 is the resonance angular velocity, R is the resistance value of the resonance circuit, and L is the inductance) changes and a phase shift occurs. At the same time, the resonance frequency also changes, but resonance is possible.

FIG. 3 shows a detailed configuration of the timing control circuit 4, in which 401 is an oscillator (OSC), 402 is a frequency dividing counter, and 4
03,404 is a NAND gate, 405 is a transmission terminal, 406 is a reception terminal, 407,408 is a reception switch, 409,410,4111 is an amplifier, 412 is a mechanical filter, and 413 is a phase detector (PS
D) and 414 are low-pass filters (LPF) 415a and 415b are comparators, and 416a and 416b are output terminals.

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

A clock pulse of, for example, 910 KHz generated from the oscillator 401 is divided into 1/2 and 1/32 by the frequency division counter 402.
One input terminal of the NAND gate 403 receives the pulse signal A of 455KHz divided by 1/2, and the other input terminal of the pulse signal of 28.44KHz divided by 1/32 (pulse width 1
7.6 μs) is input and the output is further NAND gate 4
It is sent to 04 and, as shown in FIG. 4, 45 every 17.6 μs.
It becomes the signal B that outputs or does not output the 5 KHz pulse signal.

The signal B is transmitted to the antenna coil 13 via the transmission terminal 405 and further transmitted as a radio wave. At this time, for example, when the input pen 2 is brought close to the antenna coil 13 and the core 221 is in the direction intersecting with the loop (tablet surface) of the antenna coil 13, the tuning circuit 22 resonates with the transmitted electric wave. To do. Since the circuit continues to resonate while being attenuated while the transmission on the transmission side is stopped, a signal C as shown in FIG. 4 is generated, and the signal C is transmitted as a radio wave from the coil 222 and the antenna Received by the coil 13.

Since the reception changeover switches 407 and 408 are changed over every 17.6 μs by the 28.44 KHz pulse signal, the signal from the reception terminal 406 is taken in only during the transmission stop period. When the reception signal switch 225 is off, the signal D shown in FIG. 4 is obtained. The received signal D is amplified by the amplifiers 409 and 410 to become the signal E, the noise component is removed through the mechanical filter 412 having the resonance frequency of 455 KHz, and the signal is sent to the phase detector 413 via the amplifier 411. The amplifier 410 has an automatic level control function,
The signal E has a constant amplitude.

The pulse signal A of 455 KHz is input to the phase detector 413. At this time, the phase of the reception signal E matches the phase of the pulse signal A, so that the reception signal E as shown in FIG. A signal F obtained by folding back the signal E is output.

The signal F is converted into a flat signal by the low-pass filter 414 having a sufficiently low cutoff frequency and input to one of the input terminals of the comparators 415a and 415b. A predetermined threshold voltage + VT is previously input to the other input terminal of the comparator 415a, the output of the low-pass filter 414 is compared with the threshold voltage + VT, and a high (H) level signal Ga is output to the output terminal 416a.
Is output.

Whether the input pen 2 is away from the antenna coil 13
Or if it is not in a position to intersect with the antenna coil 13,
The signal D uniformly becomes "0" level as shown by D'in FIG. 4 or becomes a signal of a minute amplitude, and the signal Ga also becomes low (L) level. Therefore, it is identified whether or not the input pen 2 has approached the tumbling surface in the writing posture.

Next, in explaining the case where the switch 225 is turned on, the phase detector 4 including the case where the switch 225 is turned off is included.
The operation waveforms of 13 will be described.

Assuming that the input signal of the phase detector 413 is a signal obtained by dividing the frequency by the frequency dividing counter 402 by eR, refer to FIG. 5A. Since this is a square wave with an amplitude of 1, its angular velocity is ωR. Then, by Fourier expansion, eR = (4 / π) {sinωRt + (1/3) sin3ωRt + (1/5) sin5ωRt + ...} (1) The signal from the amplifier 411 is defined as ei, which is the maximum value Es, the synchronous component eS of the angular velocity ωS, and the maximum value Es.
Assuming that N and the asynchronous component eN which is the noise of the angular velocity ωN, the angular velocity ωS = ωR, then ei = eS + eN = ESsinωRt + ENsinωNt (2).

Here, when the switch 225 is off, the signals eR and eS are in phase, and when the output of the phase detector 413 is eO, eO = eR × ei = (4 / π) {ESsinωRt} {sinωRt + (1 / 3) sin3ωRt + ......} + (4 / π) {ENsinωNt} {sinωRt + (1/3) sin3ωRt + ......} = (4 / π) ES {sin 2 ωRt + (1/3) sinωRt · sin3ωRt + ...... } + (4 / π) EN {sinωNt ・ sinωRt + (1/3) sinωNt ・ sin3ωRt ＋ ……} …… (3). Here, since only the sin ₂ ωRt in the first term of the equation (3) contains a DC component and the others are AC components, attention is paid to only the DC component as the output of the low pass filter 414 in the next stage,
If this is DC output ▲ ▼, sin ² ωRt ＝ (1 /)
From {1-cos2ωRt}, ▲ ▼ = (2 / π) ES (4) Expression (4) is the average value of the signal eO in FIG. 5 (A). At this time, the signal Ga of the comparator 416a becomes high level as described above.

Next, when the switch 225 is turned on by pressing the core body 24 between the tablets, φ = 180 ° where φ is the phase difference between the signals eR and eS, and the first term of the equation (3) is e. ′
Letting O be e'O = (4 / π) ES {sin (ωRt −φ) sinωRt} = (4 / π) ES (1/2) {cosφ−cos (2ωRt + φ)} …… (5), Since the second term of the equation (5) is the AC component, the DC output ▲ ▼ becomes ▲ ▼ = (2 / π) EScosφ …… (6), and from φ = 180 °, ▲ ▼ =-(2 / π ) ES. Equation (6) is an average value of the signal eO in FIG. 5 (c), and the signal ▲ ▼ is input to the comparators 415a and 415b. The comparator 415b outputs a predetermined threshold voltage −V.
After being compared with T, a high level signal Gb is output to the output terminal 416b. On the other hand, the signal Ga of the comparator 416b becomes low level.

When the switch 225 is off, the signal eO is always higher than the threshold voltage −VT, and the output signal Gb thereof is always low level.

The signals Ga and Gb are sent to the position detection circuit 3. In the position detection circuit 3, when the logical sum of the signals Ga and Gb is "1", the signal detection operation is performed, and when it becomes "0". Assuming that the position detection operation is unnecessary, it stops after a few seconds.

Further, the signal Gb is also used alone, and is defined to be in the pen-down state when the signal Gb is at the high level and not in the pen-down state when the signal Gb is at the low level. When the input pen 2 is operated on the tablet 1 and the tip of the input pen 2 is pressed on the tablet 1 at the position where the coordinate input is desired, the coordinate input is performed.

(Effect of the invention) As described above, according to the present invention, a code is not required between the position indicator and other circuits, and it is only necessary to provide a tuning circuit including a coil and a capacitor.
It eliminates the need for a complicated signal generation circuit and battery, etc. as in the past, and it can be used while the pen-type position indicator can detect whether the pen axis direction is held at a predetermined angle or more with respect to the tablet of the coordinate input device. Since it is possible to detect whether or not the state has been reached, it is possible to control whether or not to perform the position detection operation, etc. with extremely good operability according to the attitude of the position indicator, and stabilize the use state of the position indicator. Can be detected.

[Brief description of drawings]

FIG. 1 is a perspective view of a position indicator showing an embodiment of the present invention, FIG. 2 is a sectional view of an input pen, FIG. 3 is a block diagram of a timing control circuit, and FIG. 4 is a waveform of each part of FIG. 5 and 5 are waveform charts for explaining the operation of the phase detector shown in FIG. 1 ... Tablet, 2 ... Input pen (position indicator), 3
...... Position detection circuit, 4 …… Timing control circuit, 13 ……
Antenna coil, 14 ... coordinate input range, 22 ... tuning circuit, 221 ... core, 222 ... coil, 223a ... first capacitor, 223b ... second capacitor, 225 ... switch, 415a, 415b ……comparator.

Claims (4)

[Claims] 1. A state detection of a position indicator which detects whether a pen type position indicator is held at a predetermined angle or more with respect to a tablet of a coordinate input device and is in a use state. A pen-type position indicator including a coil and a capacitor whose axial direction substantially coincides with the pen axis direction of the position indicator, and changing any one of these values in accordance with the state of use. Provides a synchronizing circuit that emits radio waves in response to an external signal at substantially the same frequency and with a change in phase, and the radio wave generating means provides substantially the same frequency as the tuning frequency and the axial direction of the tablet is predetermined. Radio waves that can be crossed only to the coils with the above angles are transmitted, and the radio waves are received by the radio wave detection means, and the level of the received radio waves is above a certain level. The pen-type position indicator detects that the direction of the pen axis with respect to the tablet is held at an angle of a predetermined value or more and detects a change in the phase of the received radio wave with respect to the transmitted radio wave. A position indicator status detection method characterized by detecting that the position indicator is in use. 2. The state detecting method of the position pointing device according to claim 1, wherein the generation of the radio wave and the detection of the radio wave are alternately performed by the same coil. 3. The state detecting method for a position pointing device according to claim 1 or 2, wherein generation of radio waves and detection of radio waves are performed alternately. 4. An antenna coil provided around a coordinate input range of a tablet of a coordinate input device is used as a coil for generating and detecting a radio wave, and a pen type position indicator has a predetermined pen axis direction with respect to the tablet. The position detecting method according to any one of claims 1 to 3, wherein the position detecting operation is performed only when the position indicator is held at the above angle.