JPH0279114A - Coordinate position detector - Google Patents

Abstract

PURPOSE:To eliminate the necessity of providing a power source, etc., on an input means side in a united state and, at the same time, to improve the operability of the title detector by providing an input means which is set to the processing mode when a capacitor capacity is switched by the selection of a switch. CONSTITUTION:A loop coil 1 for oscillation and another loop coil 2 for reception are provided on a detection plate for coordinate input and the coils 1 and 2 are respectively connected with a transmission and reception circuits 4 and 5. The selecting function of an input pen 30 is constituted of capacitors C1 and C2 having different capacities and selection switches SW1 and SW2, which are respectively connected with a capacitor in parallel, and a necessary mode is selected and inputted by turning on either one of the switches. At the time of selecting a mode, the phase of received signals is advanced or delayed depending upon the turned-on switch. A phase detection circuit detects the width of the phase lag by comparison and inputs the number of clock pulses during the width to a CPU after counting. The CPU detects the phase difference from the count value and judges the functional mode selected by the switch SW1. Therefore, the operability can be improved.

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention relates to a coordinate position detection device used when inputting information such as handwritten characters or figures into an electronic device such as a computer using an input pen or the like. More specifically, the present invention relates to an electromagnetic induction type coordinate position detection device for detecting a contact position of an input pen on a coordinate input detection plate.

(b) Conventional technology The electromagnetic induction type coordinate position detection device uses a detection board for coordinate input in which loop coils are arranged at regular intervals. An induced voltage is generated by electromagnetic induction in the induction coil of the input bend that is in contact with the board, and the capacitor connected to the induction coil is charged.Then, the loop coil is switched and connected to the receiving circuit, and as the capacitor discharges. By detecting the signal flowing through the loop coil, the contact position of the input ben was determined.

(C) Problems to be Solved by the Invention Incidentally, in the coordinate position detection device as described above, in addition to simple coordinate input, there are cases where a selection function of various processing modes such as angle input is provided. Conventionally, mode selection has been done by giving an infrared command from the input pen, and using this command to adapt the receiving circuit to the selected processing mode.

Therefore, a power source and the like for infrared ray irradiation are required on the input pen side, resulting in a problem that the pen becomes large and heavy, resulting in poor operability. Additionally, if the infrared rays are unexpectedly blocked by a hand or the like, there is a problem in that the selected processing mode cannot be identified.

The object of the present invention is to provide a coordinate position detection device that solves these problems.

(d) Means for Solving the Problems In this invention, the input means is provided with a switch for selectively changing the capacitance of the capacitor, and the input means is provided with a switch for selectively changing the capacitance of the capacitor. The present invention is characterized by a coordinate position detecting device that includes a circuit that detects the deviation width by comparing it with a reference signal, and a control circuit that identifies the switch that changes the capacitor capacity based on the deviation width.

(e) Effect According to the present invention, when a switch is turned on on the input means side to select a desired processing mode and change the capacitance of the capacitor, the loop coil side changes the phase of the received signal with respect to the reference signal due to the change in capacitance of the capacitor. The phase shift width is detected, the phase shift width is referred to in the switch identification table, the switch that changed the capacitor capacity is identified, and the input processing mode is automatically determined.

(f) Effects of the invention In this way, since the processing mode is input by changing the capacitor capacity by selecting a switch, there is no need to integrally equip the input means with a power supply, etc., and the input pen or cursor can be miniaturized. As a result of being lightweight, operability is extremely high. At the same time, since it is not an infrared method, input errors due to unexpected shading do not occur.

(g) Examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a coordinate position detection device according to the present invention.
The plate surface constituting each of the shafts is the oscillation loop coil 1.
and the receiving loop coil 2 are separately arranged on the coordinate input detection plate 3 shown in FIG.

The oscillating loop coil 1 is connected to the transmitting circuit 4, and the receiving loop coil 2 is connected to the receiving circuit 5. Therefore, the oscillating loop coil 1 receives the time width shown in FIG. , generate an induced voltage by electromagnetic induction in the induction coil of the input pen or cursor, fill the capacitor C connected to the induction coil, and then switch to reception for the time width shown in Fig. The electric charge C is discharged into the induction coil (FIG. 2 C), and the reception signal shown in FIG.
The contact coordinate position of the input pen (hereinafter abbreviated as input pen) is determined.

To explain further, since the X-axis and Y-axis are the same, one example is that as shown in Figure 3, one loop coil 1 for transmitting is provided for every eight loop coils 2 for receiving. . That is, while the pattern pitch of the oscillating loop coil 1 is widened, the receiving loop coils 2 are arranged in large numbers at a narrow pitch, for example, with four fins. MPX is a switch element for switching reception, and FET is a switch element (44 field effect transistor) for switching transmission.

Furthermore, 7 is a common line for oscillation and reception.

As described above, the receiving loop coils 2 are arranged at four intervals, and each eight of them is grouped into a block, and a required number of such blocks 8 are arranged. As shown in FIG. 3, the receiving loop coils are always used to pick up received signals in a loop formed by three coils of the same rank in each of three adjacent blocks. For example, the first block of each of the three blocks 8
The second receiving loop coil 2 of each block 8 is used to pick up the received signal, and then the second receiving loop coil 2 of each block 8 is used to pick up the received signal, scanning in a time-division manner.

If the received signal is picked up with three loops in this way, the received guidance signal can be received larger (three times) than in the case of one loop, leading to improvements in the S/N ratio and detection accuracy.

Further, by using a three-line loose configuration, the induced voltage generated in the common line 7 can be canceled and distortion of the received signal can be eliminated.

In other words, if the induction coil L is touched in the state shown in FIG. The induced voltage on the line 7 side is canceled out.

Without such a configuration, the induced voltage on the common line 7 would vary depending on whether the input pen's contact position is close to or far from the common line 7, and this would affect the received signal picked up from the receiving loop coil. This will cause a detection error.

The input pen is not necessarily connected to either receiving loop line 2.
It is not necessarily placed directly above the receiving loop line, but rather it is contacted between the receiving loop lines as shown in FIG.

In this case, the coordinates cannot be specified unless the CPU 6 determines which position the input pen is on with respect to the receiving loop line. Left side of loop line A
If the current is at the position shown in FIG. 2, current flows from line 2a to line 2b in the direction of the solid arrow.

However, if it is at position B on the right side with respect to line 2b, the current flows from line 2b to line 2c in the direction of the broken line arrow, and the direction of the current flowing on receiving loop line 2b is reversed. As a result, the phase of the received signal is inverted as shown in port 42 of FIG. Therefore, the CPU 6 can detect the input pen using this transfer/reversal data and determine the position of the input pen using the receiving loop line 2b as the reversal line.

This phase reversal detection is performed as shown in FIG.

An oscillation clock pulse signal is generated from the receive signal port or signal H in FIG. 9 using the comparator 27 in the circuit in FIG. Compare at the pulse rise point. Since the received signal is generated in the receiving loop line 2 by the discharge of the capacitor C, a certain deviation occurs between it and the oscillation clock pulse signal A, as shown in signal 2. However, at the reception signal port before inversion, only this deviation signal 2 is extracted, whereas in the reception signal E after inversion, the width of the deviation increases by the amount of inversion, like the deviation signal G. This fact is used to detect reversal.

The actual detection of the deviation width signals 2 and 7 is performed in the circuit shown in FIG.
The waveform is shaped into a rectangular wave by the phase detection circuit 28, and by comparing it with the oscillation clock pulse signal A, the deviation of the signal 2 and 2 is detected.

Further, the phase detection circuit 28 detects a clock pulse (16MH
It has a counter that is driven by z), and the counter measures and outputs the width of each shift signal in the form of a count value.

When the amount of this shift is larger than the set value for detecting phase inversion, the CPU 6 determines that there is a phase inversion.

In this way, the inversion line of the received signal is determined by phase inversion, and it can be determined which side of the inversion line the input pen is touching.

Furthermore, unless the distance from the reversal line can be measured, the center position of the input pen, that is, the coordinates, cannot be specified, so the CPU 6 performs the following processing.

In other words, if the center P of the input pen is located at the position shown in Figure 7 A or Figure 8 A, (the vertical line in each figure A is 4 m +
(pointing to the receiving loop coil at intervals), the induced signals having peak values such as for each port or figure are taken out in a time-sharing manner. Since the CPU 6 sequentially stores the output of the receiving loop line (line 2b explained in Fig. 5) in the built-in RAM, the induced voltage (peak The count value corresponding to the value) is picked up, and how far the center P is from the reversal line is calculated using the value obtained by a-b subtraction.

The opening in FIG. 7 shows the case where the center part P of the input pen is located in the center between the receiving loop lines, and the count values at specific points a and b are equal.

On the other hand, Fig. 8 (a) shows the case where the center P of the coil L shown by the solid line in Fig. 8 (a) is on the side close to the reversal line side and is a positive value, and Fig. 8 (c) shows the case where the center P of the coil L shown by the solid line in Fig. 8 This is when the center P of the coil L, indicated by the chain line, is on the side far from the reversal line, and represents a negative value.

The above processing is performed by the clock count circuit 9 shown in FIG. 10, and the output signal obtained by slicing the output of the integrating circuit 26 at a predetermined level is counted by the clock count circuit 9 based on the clock pulse (8 MHz) and inputted to the CPU 6. .

The CPU 6 sequentially stores this count value, and when a phase inversion line is specified as described above, the two ports a before this line are
Then, the count value of the second to last row is read out, this is subtracted, and the coordinate value is calculated from the difference value.

Next, the operation of the implementation circuit shown in FIG. 10 will be explained. The synchronous timing circuit 10 uses the output of the oscillation circuit 11 to send a synchronous signal to the sine converter 12.

This synchronization signal is sent to the switch element FET for oscillation and reception.
, MPX switching timing (2 MHz), and is a signal for identifying an input pen (500 KHz) and a cursor (250 KHz) as input means.

The sine converter 12 outputs an oscillation signal converted into a positive magnetic wave using the synchronization signal, and sends this to the current boost circuit 1.
After changing the current to a large current in step 3, the oscillation decoder 14 causes a large current to flow through the oscillation loop coil while switching the switching element FET.

As a result, the capacitor C of the input pen that touched the coordinate input detection plate 3 is charged.

The coordinate input detection plate 3 described above forms, for example, an X-axis oscillation/reception loop on the top side and a Y-axis oscillation/reception loop on the back side, and these loops are constructed by crossing the configuration shown in FIG. 3 above. It is set up.

In the receiving operation, as described above, three same-order coils in three adjacent blocks constitute the receiving loop coil 2, and these three
This is performed by a scanning operation in which the ranking is shifted one by one one by one. The reception decoder 15 successively picks up the reception signals on the reception loop line 2 .

A reception amplifier circuit 16 amplifies the X-axis and Y-axis separately with corresponding amplification factors, and further sends them to a waveform shaping circuit 18 via an amplification factor switching circuit 17.

A specific circuit diagram of this waveform shaping circuit 18 is shown in FIG. 11, and includes a differential amplifier 19, a bandpass filter 2
0, the received signal A in FIG. 12 which has passed through the gain switcher 21 and the amplifier 22 is rectified by the full-wave rectifier 23 as signal B in FIG. 12, and then the envelope is detected by the detector 24. The peak hold circuit 25 converts the signal C into the signal shown in FIG.

The comparator 27 converts the integral signal E into the signal A shown in FIG.
/D conversion is performed, and the output width of this signal is counted by a clock count circuit 9 to calculate the output value of the received signal.

This clock count process is the calculation of the count value of the received signal, and the clock pulse (8M H2) is given to the clock count circuit 9 from the oscillation circuit 11, and the comparator output shown in FIG. The clock pulses are counted during the signal width from the point in time, and the count value is input to the CPU 6.

The CPU 6 sequentially stores the input count values as the magnitude of the received guidance signal.

On the other hand, the signal shown in FIG. 12A output from the amplification factor switching circuit 17 is directly passed through the comparator 27, shaped into a reception clock pulse signal as shown in FIG. 9C or shown in FIG. 9, and sent to the phase detection circuit 28. In the phase detection circuit 28, the phase inversion line as described in FIG.
Hz), this deviation Jl (canlant value) is calculated.

In addition, the CPU 6 calculates the peak value (count fi!f) of the guidance signal of the reception loop line at the second specific point a, b (see Figures 7 and 8) before and after this reversal line.
is picked up, and the coordinate specifying process described in FIGS. 7 and 8 is performed.

Note that the processing of the CPU 6 for specifying the coordinates described in FIGS. 7 and 8 only needs to be performed on the reception loop coil portion where the input pen is located, and processing on other portions is unnecessary.

For this purpose, from the peak hold circuit 25 to the comparator 2
When the signal outputted via 7 has a set level, this signal is assumed to be within the range where the input pen exists, and is input to the CPU 6 as a tight detection signal. Process only the part of the receiving loop coil that is present.

Then, according to the above processing data, the CPU 6 stores the expansion ROM.
A circuit 29 is used to output the coordinate values of the input pen.

Incidentally, the input pen or cursor is provided with a plurality of selection functions such as selection of various processing modes.

In this invention, this selection function consists of capacitors CI, C2, etc. of different capacities connected in parallel to the capacitor C of the input pen 30 and cursor 31, and selection switches SWI, SW2, etc., as shown in FIG. , select and input the required mode by turning on the switch.

On the receiving side, the CPU 6 operates as follows to detect the selected function.

As described above, the phase detection circuit 28 detects the phase inversion line as a phase difference count value, so this process is utilized.

That is, the received signal is input from the amplification factor switching circuit 17 to the phase detection circuit 28, but which switch S
If the received signal is A in Fig. 15 when WI, SW2, etc. are not turned on, then when the switch is turned on and other capacitors C1, C2, etc. are used in parallel with capacitor C, the capacitors used in parallel Depending on the capacity of , in other words, depending on which switch is turned on, the received signal leads or lags in phase with respect to the received signal in A, as shown in Figure 15 (a) to (e).

For example, when switch SW1 is turned on as shown in Fig. 14, the received signal at that time shifts in the direction in which the phase advances.
The phase detection circuit 28 compares and detects the width of this phase shift using the received clock pulse signal (FIG. 14 C) and the oscillation clock pulse signal (FIG. 14 B), and detects the width of this phase shift between this width (FIG. 14 H). Count the number of tarok pulses, and
Enter.

Then, the CPU 6 detects the phase difference based on the count value, and
Refer to the switch identification table for that value, and
The function mode selected by I is determined.

Note that the phase difference shift due to each switch SWI to SW4 (
count value) is determined by the above-mentioned phase inversion line detection process (9th count value).
Since the deviation is much smaller than that of the process shown in the figure, the two can be clearly distinguished.

This has the advantage that coordinate value detection and switch identification can be performed simultaneously using the same guidance signal (received signal).

In addition, in the correspondence between the configuration of the present invention and the above-described embodiment, the oscillation loop line of the present invention corresponds to the oscillation loop line 1 of the embodiment, and similarly, the reception loop line is as follows. Receiving loop line 2.2a
, 2b, and 2C, the coordinate input detection plate corresponds to the coordinate input detection plate 3, the loop coil reception circuit corresponds to the reception circuit 5, and the circuit for comparing the phase shift width corresponds to the phase detection circuit 28. The control circuit corresponds to the CPU 6, the input means corresponds to the input pen 30 or the cursor 31, the induction coil corresponds to the induction coil L, and the capacitor corresponds to
The switches correspond to capacitors C, CI, C2, C3, and C4, and the switches are switches SWI, SW2 . SW3゜SW4
In response to this, the means to switch the loop coil is a switch element FET.
This invention is not limited to the configuration of the above-described embodiment.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Fig. 1 is a conceptual diagram of a coordinate position detection device, Fig. 2 is a timing chart of oscillation and reception of Fig. 1, and Fig. 3 is a configuration diagram of an oscillation/reception loop pattern. , Fig. 4 is an explanatory diagram of the operation of the receiving loop coil, Fig. 5 is an explanatory diagram of the phase inversion line detection operation, Fig. 6 is a diagram of the received signal waveform of Fig. 5, and Figs. 7 and 8 are the input pen and guide. Correspondence diagram with signals, Figure 9 is a timing chart of phase inversion detection processing operation, Figure 10 is an oscillation/reception control circuit diagram, Figure 11 is a specific circuit diagram of a waveform shaping circuit, and Figure 12 is a diagram of the 11th waveform shaping circuit.
13 is a circuit configuration diagram of the cursor and input pen, FIG. 14 is an explanatory diagram of switch identification operation, and FIG. 15 is a received signal waveform diagram at switch 08. 1...Oscillating loop line 2.2a, 2b, 2c...Receiving loop line 3...
・Detection board for coordinate input 5... Receiving circuit 6... CPU
28... Phase detection circuit 30... Input pen 31... Cursor L... Induction coil C, CI, C2, C3, C4... Capacitor SWI,
SW2. SW3. SW4...Switch FET...Switch element MPX...Switch element -Toke,) Uke 44
No. 6, Fig. 9, I'm dead, the biggest cow vivryi arrogant Y'2 in 4, -to 30 ・λIE gun 31 ・Ka-sol L 艷 Coil c, ci-c 4 ・Kondenwa. Figure 14 Switch 1 Switch 1 Singing 2 Figure 15

Claims (1)

[Claims] (1) An input means comprising an induction coil and a capacitor connected to the induction coil is brought into contact with a coordinate input detection board on which loop coils are arranged at regular intervals, and the capacitor is charged by an oscillation signal flowing through the loop coil. The coordinate position detecting device receives the discharge with the loop coil, wherein the input means includes a switch for selectively changing the capacitance of the capacitor, and the loop coil receiving circuit has a capacitor capacitance of the received signal taken out from the loop coil. A coordinate position detection device equipped with a circuit that detects the phase shift width due to switching by comparing it with a reference signal, and a control circuit that identifies the switch that changed the capacitor capacity based on the shift width.