JPH0319565B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention detects the presence or absence of a position indicator at a predetermined position on a tablet of a coordinate input device, particularly detects the pen-down state of the position indicator. It concerns a suitable method for doing so.

(Prior Art) As a method for detecting the state of a position indicator of a conventional coordinate input device, especially a method for detecting a pen-down state, for example, a state of a position indicator that specifies only the coordinate position to be input on a tablet (hereinafter referred to as a pen-down state) is known. A method of detecting the position indicator is to provide a switch means in the position indicator, turn the switch means on (or off) only when the pen is down, and generate a timing signal based on the on (or off) of the switch means. Some devices were configured to send the information to the position detection circuit via a cord or using ultrasonic waves or infrared radiation.

(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., making the configuration complicated, large and heavy, which reduces the operability of the position indicator. There was a problem in that it made things 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 Problems) In order to solve the above-mentioned problems, the present invention detects the state of a position indicator that detects whether or not the position indicator of a coordinate input device exists at a predetermined position on the tablet. The method includes transmitting radio waves from the tablet side, and using the radio waves to excite a tuned circuit provided in the position indicator and which becomes in a certain active state when the position indicator is present at the predetermined position, A position where the position indicator detects that the position indicator is present at the predetermined position when a radio wave is received on the tablet side and the received radio wave is a radio wave transmitted from the tuned circuit in the certain active state. A method for detecting the state of an indicator, and a method for detecting a pen-down state of a position indicator of a coordinate input device, the method comprising: transmitting radio waves from a radio wave generating means; A tuned circuit configured when the device is in the pen-down state is excited, a radio wave is received by the radio wave receiving means, and when the radio wave transmitted from the tuned circuit is received, the position indicator is in the pen-down state. This paper proposes a method for detecting the pen-down state of a position indicator.

(Function) According to the present invention, when the position indicator is present at a predetermined position on the tablet and its tuning circuit is in a certain active state, the tuning circuit is excited by radio waves transmitted from the tablet side. and transmits similar radio waves. The radio waves are received by the tablet, but since these radio waves are emitted from the tuned circuit that is in a certain active state, the presence of the position indicator at a predetermined position on the tablet is detected. Ru.

Further, according to the present invention, when the position indicator is in the pen-down state and its tuning circuit is configured, the tuning circuit is excited by the radio waves transmitted from the radio wave generating means and transmits similar radio waves. do. The radio wave is received by the radio wave receiving means, and since this radio wave is a radio wave transmitted from the configured tuning circuit, it is detected that the position indicator is in the pen-down state.

(Example) Hereinafter, the method for detecting the state of a position indicator of the present invention will be specifically described based on the illustrated example. Note that here, a description will be given of an apparatus that detects a pen-down state.

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

The tablet 1 includes a tablet main body 12 and an antenna coil 13 housed in a casing 11 made of a non-metallic material such as synthetic resin.
2 is connected to the position detection circuit 3, and the antenna coil 13 is connected to the timing control circuit 4.

The tablet main body 12 is driven by the position detection circuit 3 and constitutes a detection section that detects the position specified by the input pen 2. The tablet main body 12 is arranged approximately at the center of the housing 11. Note that a frame 14 drawn on the top panel 11a of the housing 11 indicates the coordinate input range.

The tablet main body 12 and the position detection circuit 3 are, for example, those disclosed in the patent application filed by the present applicant.
``Position detection device'' of No. 59-32244 (JP-A-60-
176133) or the "coordinate position detection device" of Japanese Patent Application No. 58-238532 (see Japanese Patent Application Laid-open No. 129616/1982).

The antenna coil 13 is formed by disposing a conductive wire covered with an insulating coating such as vinyl chloride around the coordinate input range of the tablet main body 12, here, on the back surface of the top panel 11a of the housing 11 around the frame 14. It is something. In the illustrated example, the turn is one turn, but it may be a plurality of turns if necessary.

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

Figure 2 shows the detailed structure of the input pen 2, in which the pen shaft 23 is made of a non-metallic material such as synthetic resin.
Inside, from the tip end, there is a core 24 of a ballpoint pen or the like, a bar magnet 21 with a through hole that can slidably accommodate the core 24, a coil spring 25, a switch 221, a cored coil 222, A tuning circuit 22 consisting of a capacitor 223 and a variable capacitor 224 is integrated and built-in,
A cap 26 is attached to the rear end.

The switch 221 presses the core body 24, for example, by pressing its tip against the tablet surface.
When it is pushed into the pen barrel 23, it is pressed by the rear end via the coil spring 25 and is turned on, at which time the tuning circuit 22 is configured, that is, becomes active. Also, as shown in Figure 3,
The capacitor 223 and the variable capacitor 224 are connected in parallel with each other, and one end of the coil 222 is connected to one end of the capacitor 223 via the switch 221, and the other end of the coil 222 is connected to the other end of the capacitor 223 and the variable capacitor 224. It constitutes a resonant circuit.

Note that the values of the coil 222, capacitor 223, and variable capacitor 224 are such that they resonate (synchronize) with the frequency of the radio waves transmitted from the antenna coil 13.
selected as the value.

FIG. 3 shows the detailed configuration of the timing control circuit 4. In the figure, 401 is an oscillator, 402 is a frequency division counter, 403 and 404 are NAND gates,
05 is a transmitting terminal, 406 is a receiving terminal, 407,4
08 is a reception selector switch, 409, 410, 41
1 is an amplifier, 412 is a filter, 413 is a phase detector, 414 is a low-pass filter, 415 is a converter, 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 910kHz clock pulse generated by the oscillator 401 is divided by half by the frequency division counter 402.
and divided into 1/32. nand gate 403
One input terminal of the
A 455kHz pulse signal A is input, a 28.44kHz pulse signal whose frequency is divided by 1/32 is input to the other input terminal, and the output is further input to a NAND gate 4.
04, as shown in Figure 4, 28.44k
This is signal B, which outputs or does not output a 455kHz pulse signal every Hz.

The signal B is sent to the antenna coil 13 via the transmission terminal 405, and further transmitted as radio waves. At this time, if the switch 221 in the tuning circuit 22 of the input pen 2 is on, the tuning circuit 22 resonates with the transmitted radio wave. 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 changeover switches 407 and 408 are
Since switching is performed using a 28.44kHz pulse signal, the signal from the reception terminal 406 is accepted only during the transmission stop period. When the switch 221 of the tuning circuit 22 is on, the received signal becomes a signal D shown in FIG. 4, and when it is off, it becomes a signal D'. The received signal D is amplified by amplifiers 409 and 410 to become a signal E, which is further passed through a mechanical filter 412 with a resonance frequency of 455 kHz to remove noise components, and passed through an amplifier 411 to a phase detector 413.
sent to.

The 455kHz pulse signal A is input to the phase detector 413, and at this time, if the phase of the received signal E matches the phase of the pulse signal A, the fourth
As shown in the figure, a signal F obtained by folding back the received signal E is output.

The signal F is converted into a flat signal by a low-pass filter 414 whose cut-off frequency is sufficiently low, and then passed through a comparator 41.
It is input to one input terminal of 5. A predetermined threshold voltage VT is input in advance to the other input terminal of the comparator 415, and the low-pass filter 41
The output of 4 is compared with the threshold voltage VT and output terminal 4
A high (H) level signal G is output to 16.

In the case of the signal D', both the signals E and F are at the "0" level, and the signal G is also at the low (L) level.

If the signal G is defined to be in a pen-down state when it is at a high level and not to be in a pen-down state when it is at a low level, and the signal G is sent to the position detection circuit 3, it is possible to move the input pen 2 onto the tablet 1. You can input the position by simply pressing the tip of the input pen 2 onto the tablet 1 at the position where you want to input the coordinates.

In the above embodiment, whether or not the pen is in the down state can be determined by turning on or off the switch 221 in the tuning circuit 22, but for example, the capacitance of the capacitor in the tuning circuit may be changed based on the operation of the input pen 2. With this configuration, the phase of the reflected signal can be changed, the waveform of the signal F can be changed, and the level of the low-pass filter output can also be changed, and the switch itself is not necessarily essential. Furthermore, in the case where there is no switch, the tuned circuit is always configured, that is, in an active state, but as mentioned above, there are active states in which the reflected signal has a different phase, etc., and in the present invention, these states are Among the active states, the active state when the position indicator is present at a predetermined position on the tablet is defined as a certain active state.

Further, the embodiments described so far are the most preferable examples of the present invention, and the present invention is not limited thereto. For example, the antenna coil that generates radio waves and the antenna coil that detects radio waves may be formed separately, Further, in this case, radio waves may be generated at all times.

(Effects of the Invention) As explained above, according to the first invention, when radio waves are transmitted from the tablet side to the tuned circuit provided in the position indicator, the radio waves are transmitted from the tuned circuit in a certain active state. According to the second invention, it is possible to detect whether or not the position indicator is present at a predetermined position on the tablet.
When a radio wave is sent to the tuned circuit provided in the position indicator, it is possible to detect whether or not the position indicator is in the pen-down state depending on whether radio waves are transmitted from the tuned circuit in the pen-down state. , also the first
In both the position indicator and the second invention, the position indicator only needs to be provided with a tuned circuit consisting of a coil, a capacitor, etc., eliminating the need for a cord.Therefore, there is no possibility that the cord will get tangled and become tangled or break due to fatigue. In addition, conventional ultrasonic and infrared transmitters, batteries, etc. are no longer required, making it lighter and less expensive, and eliminating the hassle of battery replacement, making it possible to provide a position indicator with extremely good operability. There are advantages such as

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the position indicator state detection method of the present invention, FIG. 2 is a sectional view of an input pen, and FIG. 3 is a block diagram of a timing control circuit.
FIG. 4 is a waveform diagram of each part of FIG. 3. 1... Tablet, 2... Input pen, 3... Position detection circuit, 4... Timing control circuit, 13...
...Antenna coil, 14...Coordinate input range, 22
...tuned circuit.

Claims (1)

[Scope of Claims] 1. A position indicator state detection method for detecting whether or not a position indicator of a coordinate input device exists at a predetermined position on a tablet, the method comprising: transmitting radio waves from the tablet side; The radio wave excites a tuning circuit that is provided in the position indicator and becomes in a certain active state when the position indicator is at the predetermined position, and the tablet side receives the radio wave, and the received radio wave A method for detecting the state of a position indicator, characterized in that it is detected that the position indicator exists at the predetermined position when the radio wave is transmitted from the tuned circuit in the constant active state. 2. The method for detecting the state of a position indicator according to claim 1, characterized in that the generation of radio waves and the detection of radio waves are performed by the same antenna coil. 3. The method for detecting the state of a position indicator according to claim 1 or 2, characterized in that generation of radio waves and detection of radio waves are performed alternately. 4. A patent claim characterized in that a tuned circuit is used in which a switch that is turned on when a position indicator is present at a predetermined position on the tablet is inserted between a coil and a capacitor that can constitute the tuned circuit. The method for detecting the state of a position indicator according to any one of the ranges 1 to 3. 5. A method for detecting a pen-down state of a position indicator of a coordinate input device, comprising: transmitting a radio wave from a radio wave generating means; A tuned circuit is excited, a radio wave is received by a radio wave receiving means, and when the radio wave transmitted from the tuned circuit is received, it is detected that the position indicator is in a pen-down state. A method for detecting the pen-down state of a position indicator. 6. A method for detecting a pen-down state of a position pointing device according to claim 5, characterized in that the generation of radio waves and the detection of radio waves are performed by the same antenna coil. 7. A method for detecting a pen-down state of a position pointing device according to claim 5 or 6, characterized in that generation of radio waves and detection of radio waves are performed alternately. 8. Claim 5, characterized in that a tuned circuit is used in which a switch that is turned on when the position indicator is in the pen-down state is inserted between a coil and a capacitor that can constitute the tuned circuit. A method for detecting a pen-down state of a position indicator according to any one of items 7 to 7.