JPH02204819A - Coordinate position detector - Google Patents

Abstract

PURPOSE:To improve coordinate detection accuracy and reliability by comparing peak values of front and rear specific piece number-th loop lines for inserting and holding a discriminated inversion line, and calculating a distance extending from the inversion line to an input means contact position from its difference value. CONSTITUTION:Even if height of an induced voltage fetched from each loop line is influenced by a height variation to a coordinate input use detection board 3 of an input means, and even if an error is generated in height of the induced voltage by a variance on a characteristic of a circuit part and a temperature drift, peak values of front and rear specific piece number-th loop lines for inserting and holding an inversion line are compared, and based on its difference value, a distance extending from the inversion line to an input means contact position is calculated. Accordingly, by eliminating the influence of an error, the distance can be calculated exactly. In such a way, an error by a height variation of the input means, an error by a variance of a characteristic of the circuit part, and an error by a temperature drift can be cancelled, and the coordinate position detector with high coordinate detection accuracy and high reliability can be obtained.

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 pen that is in contact with the board to charge the capacitor connected to the induction coil, and then the loop coil is switched to the receiving circuit and connected as the capacitor discharges. By detecting the signal flowing through the loop coil, the contact position of the input pen was determined.

(c) Problems to be Solved by the Invention By the way, in the coordinate position detection device as described above, during reception, the loop coils are sequentially switched and scanned, and the received signals carried on these loop coils are taken out one after another. It is necessary to determine the coordinate position of the input pen from the distribution of the magnitude of the induced voltage by reading and memorizing the magnitude of the induced voltage, but it is also necessary to determine the coordinate position of the input pen from the distribution of the magnitude of the induced voltage. The magnitude of the induced voltage changes due to variations in the characteristics of the circuit components of the circuit, as well as humidity drift.
Since this change acts as an error, the accuracy of coordinate detection decreases, causing reliability problems.

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

(d) Means for Solving the Problems This invention provides means for switching and scanning a group of loop coils in a time-division manner to read and store the peak values of received signals taken out from these loop coils, and means for reading and storing the peak values of received signals taken out from these loop coils. A phase detection circuit that discriminates and processes lines where the phase of the received signal is inverted, and compares the peak values of a specific number of loop lines before and after the determined inverted line of the received signal stored above. The present invention is characterized by a coordinate position detecting device including a circuit for deducing the distance from the reversal line to the input means contact position from the difference value.

(E) Effect According to the present invention, even if the height of the induced voltage taken out from each loop line is affected by a change in the height of the input means relative to the coordinate input detection plate, variations in the characteristics of the circuit portion or temperature drift Even if an error occurs in the height of the induced voltage, the peak values of a specific number of loop lines before and after the reversal line are compared, and the distance from the reversal line to the input means contact position is calculated based on the difference value. By this,
Accurate distance determination can be performed by eliminating the influence of errors.

(f) Effects of the invention As a result, errors due to changes in the height of the input means, errors due to variations in characteristics of circuit parts, and errors due to temperature drift can be canceled, realizing a coordinate position detector with high coordinate detection accuracy and high reliability. can.

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

FIG. 1 is a conceptual diagram of the coordinate position detection device according to the present invention.
The plate surfaces constituting each of the shafts, 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, and the oscillating current is passed through the oscillating loop coil 1 for the time width shown in Fig. 2 A and as shown in Fig. 2. , generate an induced voltage in the induction coil L of the input pen 30 or the cursor with the electric 'f11 induction, fill the capacitor C connected to the induction coil, and then switch to reception for the time width shown in FIG. The electric charge of the capacitor C is discharged to the induction coil L (FIG. 2 C), and the received 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 coil 2 has many narrow pitches, for example, 4aw. MPX is a switch element for switching reception, and FET is a switch element (field effect transistor) for switching transmission.

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

The receiving loop coils 2... are arranged at 4 m intervals as described above, and each eight trees are grouped into blocks, and a required number of such blocks 8... are provided. 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, 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.

In addition, the three-loop configuration cancels the induced voltage generated in the common line 7 and eliminates distortion of the received signal.

In other words, if the induction coil L is touched in the state shown in FIG. 4, currents in opposite directions will flow through the common line 7 on both sides of the central loop coil 2b of the three-loop configuration. The induced voltage on the common 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 avoids detection errors.

The input pen 30 is not necessarily placed directly above any of the receiving loop lines 2, but is brought into contact between the receiving loop lines as shown in FIG.

In this case, the coordinates cannot be specified using the GJ unless the CPLI 6 determines where the input pen is located relative to the receiving loop line. In FIG. 5, if the receiving loop line 2a, 2b, 2c is located at a position A on the left side of the receiving loop line, current flows from the line 2a to the line 2b in the direction of the solid arrow.

However, if the current is on the right side B with respect to the line 2b, the current flows from the inlet 2b to the line 2c in the direction of the dashed arrow, and the direction of the flow on the reception loop line 2b is reversed. As a result, the phase of the received signal is inverted as shown in the signal 41 in FIG. Therefore, the CPIJ 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 discharging the capacitor C, a certain deviation occurs between it and the oscillation clock pulse signal A like a signal port. However, at the receiving signal port before inversion, only this deviation signal port is taken out, whereas in the receiving signal E after inversion, only the reversing valve increases the deviation width 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 (16MF
-12>, and the counter measures and outputs the width of each shift signal as 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 found by inverting the phase, and it can be determined which side of the inversion line is being touched.

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

That is, if the center P of the input pen is located at the position shown in Figure 7A or Figure 8A, the vertical line in each figure is 4ae.
(referring to the receiving loop coils spaced apart by m), the induced signals having the same peak value or peak values as shown in the figure are extracted 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*m pressure at the second specific points a and b sandwiching the phase inversion line is stored in the built-in RAM. The count value corresponding to (peak value) is picked up, and how far the center P is from the reversal line is calculated using the numerical value obtained by a-bilii calculation. 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 when 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 and is a positive value, and Fig. 8 (c) shows the case in which the center P of the coil L shown by the solid line in Fig. 8 (a) is a positive value. The chain line indicates the case where the center P of the coil L is on the far side from the reversal line, which is a negative value.

The above processing is performed by the clock count circuit 9 in FIG. and input it to the CPU 6.

The CPU 6 sequentially stores this count value, and when a phase inversion line is specified as described above, the second count value a before this line is
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 (2MH2) timing, and is a signal for identifying an input pen (500Kf-1z) as an input means and a cursor <250Kf-1z).

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.

This causes the input pen 3 to touch the coordinate input detection plate 3.
0 capacitor C 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 done in a scanning motion that shifts the ranking of the waterwheels one after another. 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 in FIG. 12 that 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 envelope 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 (8MH2) is given from the oscillation circuit 11 to the clock count circuit 9, and when the comparator output of FIG. The clock pulses are counted during the signal width from and to the signal width, and the count value is input to the CPU 6.

The CPtJ6 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.
In H2), this deviation ω (canlant value) is calculated.

In addition, the CPU 6 picks up the peak value (count value) of the 1m number of the receiving loop line at specific points a and b of the two wood grains in the front and back (see Figs. 7 and 8) with this reversal line as the border, 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 inputted to the CPU 6 as a tight detection signal, and the CPLJ 6 outputs this tight detection signal. Process only the part of the receiving loop coil that is present.

Then, based on the above processing data, CPLJ6
The M circuit 29 is used to output the coordinate values of the input pen.

In this way, the receiving circuit picks up the peak value of the guidance signal of the receiving loop line of a specific number of lines before and after the reversal line (two ports on the front and back) that sandwich the reversal line, and specifies the coordinates from the difference between the two peak values. The coordinate detection accuracy becomes high.

That is, even if the received signal contains errors due to changes in the height of the input pen 30 relative to the coordinate input detection plate 3, variations in the characteristics of receiving circuit components, or temperature drift,
This error is not taken out from each receiving loop line 2... and is placed almost equally on the received signal, so if you take out the difference value of the peak values with the same error, this difference value will be equal to the above error. Therefore, the distance from the reversal line to the input pen contact position can be accurately calculated based on the difference value (in the case of the embodiment, the difference value between the count values).

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 board corresponds to the coordinate input detection board 3, and the means for reading and storing the peak value of the received signal is the CPU.
6. Corresponds to the clock count circuit 9 and the oscillation circuit 11; The phase detection circuit corresponds to the phase detection circuit 28; The deduction circuit corresponds to the CPU 6; The input means corresponds to the input pen (or cursor) 30. The induction coil corresponds to the induction coil, and the capacitor corresponds to
Although the means for switching the loop coil corresponding to the capacitor C corresponds to the switching elements FET and MPX, the present 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 in FIG. 1; FIG. 3 is a configuration diagram of an oscillation and reception loop pattern; Figure 4 is a diagram explaining the operation of the receiving loop coil, Figure 5 is a diagram explaining the phase inversion line detection operation, Figure 6 is a waveform diagram of the received signal in Figure 5, Figures 7 and 8 are the input pen and the guided signal. 9 is a timing chart of phase inversion detection processing operation, 10 is an oscillation/reception control circuit diagram, 11 is a specific circuit diagram of a waveform shaping circuit, 12 is a 11th
FIG. 3 is a signal waveform diagram of each part of the circuit shown in FIG. 1...Oscillating loop line 2.2a, 2b, 2c...Receiving loop line 3...
・Detection board for coordinate input 6...CPU9...Clock count circuit 11...Oscillation circuit 28...Phase detection circuit 3
0...Input pen L...Induction coil C...Capacitor FET
...Switch element MPX...Switch element Fig. 1 Indication of the case 1986 Patent Registration No. 230386 Name of the invention Coordinate position detection device Representative Yoshio Tateishi (December 20, 1988) Number of inventions to be increased by the amendment Figure 10: Contents of the amendment Figure 10: Figure 10: Figure 10: Figure 10: Figure 10: Figure 10: Number of inventions to be increased by the amendment Inventory of attached documents 1 copy of amendment drawings Procedural amendment (method) Target of amendment March 3, 1990 Brief explanation of drawings in the specification Contents of amendment Page 19, line 2 of the specification 1982 2006 Patent Application No. 230386 "No. 12" is amended to the title of the invention: Coordinate position detection device "Fig. 12".

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. A coordinate position detecting device for receiving the discharge with the loop coil, the loop coil comprising: a means for switching and scanning the loop coil group in a time-sharing manner and reading and storing the peak value of the received signal taken out from the loop coil; A phase detection circuit that discriminates and processes the lines where the phase of the received signal extracted from A coordinate position detection device including a circuit that calculates the distance from the reversal line to the input means contact position from the difference value.