JPS6329829A - State detecting system for position detector - Google Patents

Abstract

PURPOSE:To detect an operating state without dropping maneuverability by forming an antenna coil and a tuning circuit, impressing an AC signal with a prescribed frequency level to originate radio waves and discriminating the state of the tuning circuit from a signal in the antenna coil at the time of stopping the origination of radio waves. CONSTITUTION:A clock pulse with 910kHz e.g. generated from an oscillator 401 is divided at its frequency into 1/2 and 1/32 by a frequency dividing counter 402 and turned to a signal B intermittently outputting a pulse signal with 455kHz every 28.44kHz. The signal B is sent to the antenna coil 13 through a transmitting terminal 405 and originated as a radio wave. When a switch 221 in the tuning circuit 22 of an input pen is ON, the circuit 22 resonates the sent wave. Since the circuit 22 continues resonation while being attenuated during the stop of origination from the transmitting side, a signal C is generated, originated as a radio wave from a coil 222 and received by the antenna coil 13.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is suitable for detecting the state of a position indicator in a coordinate input device, particularly the state of a position indicator that specifies only the coordinate position to be input. It is related to the method.

(Conventional Technique #4) Conventionally, in a coordinate input device, a method for detecting the state of a position indicator that specifies only the coordinate position to be input on a tablet (hereinafter referred to as a bend state) has been By providing a switch means on the indicator, only when the pen is down,
Some devices are configured to turn on (or turn off) the switch means and send a timing signal based on the on (or off) of the switch means to the position detection circuit via a cord or by using ultrasonic waves or infrared radiation. Ta.

(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 impairs the operability of the position indicator. In the case of a transmitter, the position indicator itself must be equipped with a transmitter, a signal generation circuit, a battery, etc., which complicates the configuration, resulting in a large and large lff1, which reduces the operability of the position indicator. There was a problem with making it worse.

An object of the present invention is to provide a method that can detect the state of a position indicator without reducing its operability.

(Means for Solving the Problem) In order to solve the above problem, the present invention includes a tablet constituting a coordinate input section, a position indicator such as a stylus pen, and a coordinate input device that drives the tablet and uses the position indicator. In a coordinate input device equipped with a position detection circuit for detecting a position, an antenna coil is provided around the coordinate input range of the tablet, a tuning circuit including a coil and a capacitor is provided in the position indicator, and the antenna coil is provided with a tuning circuit including a coil and a capacitor. A radio wave is transmitted by adding an alternating current signal of a frequency, and the state of the tuned circuit is determined from the signal in the antenna coil when the transmission of the radio wave is stopped, and the state of the position indicator is detected.

(Function) According to the present invention, the tuned circuit that receives radio waves from the antenna coil performs co-imaging at approximately the same frequency and the same or different phases, or does not resonate, depending on the state of the tuned circuit. Radio waves that are almost the same and have the same or different phases are reflected to the antenna coil or are not reflected, and based on the reflected radio waves, a signal is generated in the antenna coil that stops transmitting radio waves, or a signal is not generated. The state of the position indicator is determined and the state of the position indicator is detected.

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

The tablet 1 has a tablet main body 12 and an antenna coil 13 housed in a non-magnetic metal casing 11. The tablet main body 12 is connected to a position detection circuit 3, and the antenna coil 13 is connected to a timing control circuit 4. It is connected.

The tablet main body 12 is driven by the position detection circuit 3,
The tablet body 12 constitutes a detection section that detects a position specified by the input pen 2, and the tablet main body 12 is arranged approximately at the center of the housing 11.

Note that the frame 1 drawn on the top panel 11a of the housing 11
4 indicates the coordinate input range.

The tablet main body 12 and position detection circuit 3 include:
For example, patent application No. 59-3224 filed by the present applicant.
No. 4 “Position detection device” (Japanese Patent Application Laid-Open No. 60-176133
(see Japanese Patent Application No. 1982-238532), or the "coordinate position detection device" of Japanese Patent Application No. 1982-129616 (see Japanese Patent Application Laid-Open No. 129616/1982).

The antenna coil 13 connects a conductive wire coated with an insulating vinyl chloride shade around the coordinate input range of the tablet body 12.
Here, the upper surface panel ll of the housing 11 around the frame 14 is shown.
It is arranged on the back side of a. In the illustrated example, the turn is one turn, but it may be a plurality of turns if necessary.

The input pen 2 has a built-in magnetic generator for specifying a position, such as a bar magnet 21, and a tuning circuit 22 including a coil and a capacitor.

Since FIG. 2 shows the detailed structure of the input pen 2, the core body 24 of a ballpoint pen 8 or the like is slid inside the pen shaft 23 made of non-magnetic metal, for example aluminum, from near the tip. Bar magnet 21 with a through hole that can be accommodated in a movable manner
, a coil spring 25, and a switch 221. Coil with iron core 222. Capacitor 223 and variable capacitor 22
A tuning circuit 22 consisting of 4 and 4 is integrated and built in, and a cap 26 is attached to the rear end.

The switch 221 is turned on when the core body 24 is pushed into the pen shaft 23 by, for example, pressing its tip against the tablet surface, and the rear end is pressed via the coil spring 25 to turn on. Also, as shown in FIG. 3, a condenser 223 and a variable capacitor 224
are connected in parallel to each other, one end of a coil 222 is connected to one end of these through the switch 221, and the other end of the coil 222 is connected to the other end of these, forming a well-known parallel resonant circuit. There is.

Note that the coil 222. The numerical values of the capacitor 223 and the variable capacitor 224 are selected to resonate (tune) to the frequency of the radio waves transmitted from the antenna coil 13.

FIG. 3 shows a detailed configuration of the timing control circuit 4. In the figure, 401 is an oscillator, 402 is a frequency division counter, and 401 is an oscillator.
03, 404 is a Nantes gate, 405 is a transmission terminal, 4
06 is a reception terminal, 407, 408 are reception changeover switches, 409, 410, 411 are amplifiers, 412 is a filter, 413 is a phase detector, 414 is a low-pass filter, 4
15 is a comparator, and 416 is an output terminal.

FIG. 4 is a signal waveform diagram at each part of FIG. 3. The operation will be explained in detail below.

For example, a clock pulse of 910kHz7 generated by the oscillator 401 is divided into 1/2 and 1/2 by the frequency division counter 402.
The frequency is divided into 32. A 455 kHz pulse signal Δ divided by 1/2 is input to one input terminal of the Nant gate 403, and a 28.44 kHz pulse signal Δ divided by 1/32 is input to the other input terminal. A signal is input, and its output is further sent to the Nant gate 404, and becomes signal B, which outputs a pulse signal of 455 kHz at every 28.44 kHz, as shown in FIG. 4. .

The signal B is sent to the antenna coil 1 via the transmission terminal 405.
3 and further transmitted as radio waves. At this time,
In the tuning circuit 22 of the input pen 2, when the switch 221 is on, the tuning circuit 22 resonates with the transmitted radio waves. Since the circuit continues to resonate while being attenuated even when the transmission on the transmitting side stops, it generates a signal C as shown in FIG. The signal is received by the coil 13.

The reception selector switches 407 and 408 are as described in 28.44.
Since switching is performed using a kHz pulse signal, the signal from the reception terminal 406 is accepted only during the transmission stop period. The received signal becomes a signal shown in FIG. 4 when the switch 221 of the tuning circuit 22 is on, and becomes a signal D' when it is off. The received signals are transmitted through amplifiers 409 and 41.
0 and becomes the signal E, which further increases the resonant frequency 4
Noise components are removed through a 55kHz mechanical filter 412, and then passed through an amplifier 411 to a phase detector 413.
will be sent to.

The 455 kHz pulse signal A is input to the phase detector 413. At this time, if the phase of the received signal E matches the phase of the pulse signal A, the signal as shown in FIG. , outputs a signal F obtained by folding back the received signal F.

The signal F is passed through a low-pass filter 414 with a sufficiently low cutoff frequency.
The signal is converted into a flat signal at the step 415, and is input to one input terminal of the comparator 415. The other input terminal of the comparator 415 has a predetermined threshold voltage VT input thereto, the output of the low-pass filter 414 is compared with the threshold voltage VT, and the output terminal 416 receives a high (H) level signal. G
is output.

Note that in the case of signal R1, both signals E and F are at rOJ level, and signal G is also at low (L) level.

When the signal G is at a high level, the pen is in a down state;
By defining that the pen is not in a down state when it is at a low level and sending the signal G to the position detection circuit 3, you can operate the input ben 2 on the tablet 1 and move the input ben 2 at the position where you want to input the coordinates. The position can be input simply by pressing the tip onto the tablet 1.

In addition, in the embodiment, the switch 221 in the tuning circuit 22
For example, the capacity of the capacitor in the tuning circuit can be changed based on the operation of the input valve 2, and thereby the phase of the reflected signal can be changed. It is also possible to change the waveform of the signal F and change the level of its low-pass filter output, and the switch itself is not necessarily essential.

(Effect of ¥1 Light) As explained above, according to the present invention, not only is there no need for a cord between the position indicator and other circuits, but only a tuning circuit including a coil and a capacitor is provided. well,
There is no need for a complicated signal generating circuit or a battery as in the past, and there are advantages such as being able to provide a position indicator that can be folded over and has good operability, and its state can be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an overview of 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 diagram of each part of FIG. 3. It is. DESCRIPTION OF SYMBOLS 1... Tablet, 2... Input pen, 3... Position detection circuit, 4... Timing control circuit, 13... Antenna coil, 14... Coordinate input range, 22... Tuning circuit . .

Claims (2)

[Claims] (1) A coordinate input device comprising a tablet constituting a coordinate input section, a position indicator such as a stylus pen, and a position detection circuit that drives the tablet and detects a coordinate input position by the position indicator. An antenna coil is provided around the coordinate input range, and a tuning circuit including a coil and a capacitor is provided in the position indicator, and an alternating current signal of a predetermined frequency is applied to the antenna coil to transmit radio waves, and the transmission of the radio waves is stopped. 1. A method for detecting the state of a position indicator, characterized in that the state of the tuning circuit is determined from the signal in the antenna coil when the position indicator is moved, and the state of the position indicator is detected. (2) A switch is provided in the tuning circuit to turn on/off the connection between the coil and the capacitor, and when specifying only the coordinate position to be input, the switch is turned on (or off) and a position indicator is used. A method for detecting the state of a position indicator according to claim 1, characterized in that: