JPH03230213A - Coordinate detector - Google Patents

Abstract

PURPOSE:To eliminate the need for the cable between a main body and a coordinate indicator by obtaining the counting start signal for a counter from a signal induced on an electric conductor which is irrelevant to phase modulation. CONSTITUTION:When an oscillation circuit 4b which is incorporated in the coordinate indicator 4 is excited, the coordinate indicator 4 produces an alternating magnetic field and voltage signals are induced on respective electric conductors wired on a tablet 24. A phase modulating circuit 25 inputs a signal of a specific electric conductors among the respective electric conductors, imposes phase modulation, and outputs the phase-modulated signal as a counting stop signal for the counter 26. A detecting circuit 29, on the other hand, extract signals induced on electric conductors which are irrelevant to the phase modulation among the respective electric conductors to obtain a signal which have the same period and is in phase with the oscillation circuit 28, and outputs this signal as the counting start signal for the counter. Consequently, the signal synchronized with the oscillation circuit 4b on the side of the coordinate indicator 4 can be obtained on the side of the main body 1 even unless the coordinate indicator 4 and main body 1 are connected by a cable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides information on the location indicated by a coordinate indicator. The present invention relates to a coordinate detection device that detects coordinates.

[Conventional technology coordinate detection devices use a stylus pen that generates an alternating magnetic field,
This is a device that detects the coordinates of a position on a tablet indicated by a coordinate indicator such as a pickup or a cursor (hereinafter referred to as a cursor). A plurality of conductive wires are wired in a predetermined manner on the tablet, and by appropriately processing the voltage induced in each of the conductive wires by the alternating magnetic field generated from the cursor, the coordinates of the position indicated by the cursor can be determined. Detect. An outline of this coordinate detection will be explained with reference to the drawings.

FIG. 5 is a block diagram of a conventional coordinate detection device. In the figure, L is the cursor and la is the ffl built in cursor 1.
This is a coil for field generation. 2 is a water body of the coordinate detection device, and is indicated by a - point tag.

21 is an oscillation circuit, 22 is a frequency divider circuit that divides the signal output from the oscillation circuit 21 into a predetermined frequency, and 23 is an amplifier that amplifies the output of the frequency divider circuit 22 to produce a predetermined sine wave current. .

24 is a tablet. A plurality of conductive wires are wired to the tablet 24. There are various ways of wiring, one typical example of which is shown in FIG. FIG. 6 is a wiring diagram of the conductive wires of the tablet 24. In the figure, 24a is a first conducting wire arranged in a meandering manner in the X-axis direction, and the pitch of its -period is indicated by p. 24b is the first lead @ 24
This is a second conductive wire that is wired in the same manner as a, but with a phase shift of p/4 with respect to the second conductive wire. 24c is a conductive wire called a selector wire, and is wired in a comb-teeth shape at intervals of, for example, a pitch P so as to match the first conductor @24a. Although the conductive wires are laid out in the same manner in the Y-axis direction, illustration is omitted. In the figure, A indicates the position indicated by the cursor 1, and Q indicates the distance from the pitch start position of the lead @ 24 a to the position A.

Returning to FIG. 5, 25 is the X axis of the tablet 24.

This is a phase modulation circuit that inputs and processes signals induced in the first conductive wire and the second conductive wire in the Y-axis. 26 is a counter, a terminal SP inputs the signal from the phase modulation circuit 25, and a terminal ST inputs the signal from the frequency divider circuit 22.
, and a terminal CK into which a signal from the oscillation circuit 21 is input as a clock signal. Reference numeral 27 denotes an arithmetic processing unit consisting of a microcomputer, which calculates the coordinates of the position on the tablet 24 indicated by the cursor 1 and performs various other controls. A cable 3 is provided between the cursor 1 and the main body 2 to supply a sine wave current from the amplifier 23 to the coil 1a of the cursor 1.

Next, the operation of the above-mentioned conventional coordinate detection device will be explained in FIGS.
This will be explained with reference to the waveform diagram shown in (c). Figure 7 (
a) is the output waveform of the amplifier 23, and FIG. 7 CI)) is the waveform whose phase has been modulated by the phase modulation circuit 25. Figure 7 (C
]) is the output waveform of the counter 26, and
The vertical axis shows the count value.

When the oscillation circuit 21 is excited, a high-frequency pulse signal is output, and the frequency dividing circuit 22 divides this into a pulse signal of a predetermined frequency. A sinusoidal current of is supplied. in this case,
The pulse signal from the oscillation circuit 21 is connected to the terminal C of the counter 26.
The pulse signal from the frequency divider circuit 22 is input to the terminal ST of the counter 26, and for example, the first rising edge of the - period becomes the start signal for the counter 26. .

Now, when an arbitrary position on the tablet 24, for example, position A shown in FIG. The voltage induced in the five conductive wires 24a and 24b is input to the phase modulation circuit 25 and processed. This results in
Shown in Figure 7(b).

As shown, a signal whose phase is φ equal to 39 with respect to the signal outputted from the amplifier 23, that is, the signal outputted from the frequency dividing circuit 22, is obtained. Note that such a phase modulation circuit is
For example, it is disclosed in Japanese Unexamined Patent Publication No. 55-56230 and is well known. The phase φ is proportional to the distance @Q of the position A.

The phase modulation circuit 25 shapes the signal waveform shown in FIG. 7(b) into a pulse waveform, and outputs this to the terminal SP of the counter 26.

The counter 26 stops counting at the rising edge of the signal input to the terminal SP. The count value at that time is shown as a numerical value N in FIG. 7(c).

On the other hand, each comb tooth interval of the selector line 24c of the tablet 24 is sequentially scanned by a scanning circuit (not shown), and the comb tooth interval at which a voltage is induced is detected by the cursor 1. The detected comb tooth interval corresponds to the pitch at which the position indicated by the cursor 1 exists among the continuous pitches of the conducting wire 24a. The arithmetic processing unit 27 manually inputs the count value N from the counter 26 and the scanning signal of the selector line 24c to calculate the position iI! Calculate the coordinate values of A.

[Problems to be Solved by the Invention] When using the conventional coordinate detection device described above, the operator frequently moves the cursor 1 on the tablet surface of the main body 2. However, since the cable 3 is connected to the cursor 1, the operability is poor for the operator, and in particular, the cable 3 often gets caught in the corners of the coordinate detection device main body 1. Further, the cable 3 itself often comes into contact with objects other than the corners, and is often broken. Such disconnections actually occur frequently, and for this reason, the cable 3 is treated as a consumable item.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
An object of the present invention is to provide a coordinate detection device that can eliminate the need for a cable connecting a cursor and a main body of the coordinate detection device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a tablet in which a plurality of conductive wires are wired in a predetermined manner, and a coordinate indicator that generates an alternating magnetic field by a signal from an oscillation circuit. a phase modulation circuit that phase-modulates the signal induced in the conductive wire of the tablet by the alternating magnetic field according to the indicated position of the coordinate indicator; and a phase modulation circuit that starts counting based on the signal of the oscillation circuit. A coordinate detecting device equipped with a counter that stops counting in response to an output signal, wherein the coordinate indicator includes the oscillation circuit and a magnetic field generator that generates the alternating magnetic field, and a conductive wire wired to the tablet. Among them, a detection circuit is provided which detects a signal having the same phase as the signal of the oscillation circuit built in the coordinate indicator by a signal induced in a conducting wire that is not involved in the phase modulation, and the output signal of this detection circuit is sent to the counter. It is characterized by being used as a signal to start counting.

[Operation] When the oscillation circuit built into the coordinate indicator is excited, an alternating magnetic field is generated from the coordinate indicator in response, and a voltage signal is induced in each conductive wire wired in the tablet. The phase modulation circuit inputs the signal of a predetermined conductor among the conductors, performs phase change y4, and outputs the phase modulated signal in response to the count stop signal of the counter. On the other hand, the detection circuit detects each of the above 'j'! By extracting the signal induced in the conducting wire that is not involved in phase modulation, a signal having the same period and the same phase as the oscillation circuit is obtained, and this signal is output as the count start signal of the counter. Thereby, even if the coordinate indicator and the main body are not connected by a cable, a signal synchronized with the oscillation circuit on the coordinate indicator side can be obtained from the main body.

[Example] The present invention will be explained below based on illustrated embodiments. Fig. 1 is a block diagram of a coordinate detection device according to an embodiment of the present invention, and Fig. 2 is an internal circuit of the cursor shown in Fig. 1. FIG. 3 is a block diagram of the pen reference wave detection circuit shown in FIG. 1. In FIG. 1, 28 is an oscillation circuit that generates a clock signal for the counter 26. This oscillation circuit 28
is connected to the terminal CK of the counter 26. Reference numeral 29 denotes a pen reference wave circuit, which inputs and processes the signal of the selector line coordinated to the tablet 24. 4 shows the cursor of this embodiment. This cursor 4 is moved to the main body 2 like in the conventional device.
It is not connected with the cable 3 and is completely separated from the main body 2.

As shown in FIG. 2, the cursor 4 includes a pen coil 4a that generates an alternating magnetic field, an oscillation circuit 4b that generates an excitation signal to be supplied to the pen coil 4a, and a pen coil 4a that amplifies the signal output from the oscillation circuit 4b. An amplifier 4c is built in to supply excitation current to. By incorporating the oscillation circuit 4b and the amplifier 4C, the cable 3 in the conventional device becomes unnecessary.

The pen reference wave detection circuit 29 shown in FIG. 1 is comprised of an amplifier 29a, a filter 29b, and a waveform shaping circuit 29c, as shown in FIG. The reason why such a pen reference wave detection circuit 29 is provided is as follows. That is, as shown in FIG. 5, in the conventional device, the oscillation circuit 21, the frequency dividing circuit 22, and the amplifier 23 are provided on the main body 2 side, and
Since the cursor L is connected to Masuji Co., Ltd. 23 through the cable 3, a start signal, which serves as a reference for the stop signal (phase modulation signal) of the counter 26, can be obtained from the frequency dividing circuit 22. However, if the cursor 4 is completely separated from the main body 2 as in this embodiment, it is not possible to obtain the start signal of the counter 26, which serves as a reference. The pen reference wave detection circuit 29 is based on the base 11! This is provided to obtain a start signal.

Next, the operation of this embodiment is shown in FIGS. 4(a) and 4(b).

This will be explained with reference to the waveform diagram shown in (c). Figure 4 (
A) shows the output waveform of the counter 26, with the horizontal axis representing time and the vertical axis representing the count value. FIG. 4(b) shows the output waveform of the amplifier 4C built in the cursor 4, and FIG. 4(c) shows the waveform phase-modulated by the phase modulation circuit 25. In both cases, the horizontal axis is time, and the vertical axis is amplitude. It's great.

Here, it is assumed that the counter 26 repeatedly counts at the same period T as the oscillation circuit 4b built in the cursor 4. In this state, when the oscillation circuit 4b is excited and an arbitrary position on the tablet 24 is indicated with the cursor 4, a voltage is induced in each conducting wire according to the position as described above. Among the voltages induced in these conductive wires, the voltage induced in the selector wire is input to the pen reference wave detection circuit 29. The voltage induced in this selector line is shown in Figure 4 (
It has the same phase as the signal output from the amplifier 4c shown in b), is amplified by the amplifier 29a of the pen reference wave detection circuit 29, and after noise is removed by the filter 29b, is input to the waveform shaping circuit 29c. The waveform shaping circuit 29c outputs a pulse signal having the same phase as the waveform shown in FIG. 4(b).

The counter 26 is reset at the rising edge of the pulse signal output from the pen reference wave detection circuit 29 and starts counting. This state is shown in FIG. 4(a). That is, when a signal is output from the pen reference wave detection circuit 29 while the area shown by waveform C is being counted, the counter 26 is reset in the middle of counting (count value N') and a new one is again generated. Start counting.

On the other hand, the X-axis and Y-axis conductors 2 wired to the tablet 24
4 a, 24 b? As described above, the signal generated by Jg is input to the phase modulation circuit 25, and as shown in FIG.
4, the count of the counter 26 is stopped by the output of the phase modulation circuit 25, and the count value N at that time is read out by the arithmetic processing section 27. Thereafter, the coordinates are calculated by the calculation processing section 27.

In this way, in this embodiment, the signal induced in the selector line is used to generate the start signal for the counter, so the oscillation circuit that excites the pen coil can be separated from the main body and built into the cursor. , thereby eliminating the cable connected between the cursor and the main body.

In addition, in the explanation of the above embodiment, an example was explained in which the voltage induced in the selector wire is used as the start signal, but the invention is not limited to this, and if there is a conductor wire that is not used for phase modulation, the voltage induced in it can be used. It can be used as a start signal. or.

It is also possible to use a counter that is not driven all the time but is driven when a start signal is input.

[Effects of the Invention] As described above, in the present invention, since the count start signal of the counter is obtained from the signal induced in the conductor that is not subject to phase modulation, the oscillation circuit is built into the coordinate indicator. This makes it possible to eliminate the need for a cable between the main body and the coordinate indicator.

[Brief explanation of drawings]

FIG. 1 relates to an embodiment of the present invention. FIG. 2 is a block diagram of the internal circuit of the cursor shown in FIG. 1, FIG. 3 is a block diagram of the pen reference wave detection circuit shown in FIG. 1, and FIG. 4(a) is a block diagram of the coordinate detection device. (b) and (Q) are waveform diagrams of each part of the circuit shown in Figure 1, Figure 5 is a block diagram of a conventional coordinate detection circuit, Figure 6 is a wiring diagram of each conductor of the tablet, and Figure 7 ( a), (b), (c
) is a waveform diagram of each part of the circuit shown in FIG. 2... Body, 4... Cursor, 24...
...Tablet, 25...Phase modulation circuit, 2
6... Counter, 27... Arithmetic processing unit, 2
9...Pen reference wave detection circuit. 11i11ran

Claims (2)

[Claims] (1) A tablet on which a plurality of conductive wires are wired in a predetermined manner, a coordinate indicator that generates an alternating magnetic field according to a signal from an oscillation circuit, and a coordinate indicator that generates an alternating magnetic field according to the indicated position of the coordinate indicator by the alternating magnetic field. A coordinate detection device comprising: a phase modulation circuit that phase-modulates a signal induced in a conductive wire; and a counter that starts counting based on a signal from the oscillation circuit and stops counting based on an output signal of the phase modulation circuit. The indicator incorporates the oscillation circuit and a magnetic field generating device that generates the alternating magnetic field, and the coordinate indicator receives a signal induced in a conducting wire that is not involved in the phase modulation among the conducting wires wired to the tablet. A coordinate detection device comprising: a detection circuit that detects a signal having the same phase as a signal of the built-in oscillation circuit; and an output signal of the detection circuit is used as a count start signal of the counter. (2) The coordinate detection device according to claim (1), wherein the conducting wire not involved in phase modulation is a selector wire.