JPS599951B2 - Jidouza Hiyouyomi Torisouchinosou Sahoushiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a coordinate reading system that sequentially applies scanning signals to a large number of sense lines laid out in a matrix on a tablet and detects the indicated coordinate position of a coordinate indicator placed on the tablet. The present invention relates to an apparatus, and in particular aims to improve the data sampling rate for the movement of a coordinate indicator by improving the sense line scanning method.

First, the basic configuration of a coordinate reading device that scans a sense line will be explained using an electromagnetic induction type coordinate reading device previously developed by the present inventors as an example.

In FIG. 1, 1 indicates a tablet, Xi (Xo,
X1, ......Xn) and Yj (Yo, Y
2...Ym) are the X-axis and Y-axis sense lines laid out in a matrix on the tablet 1,
One end of each sense line Xi is connected to the X-axis scanning circuit 2, and one end of each sense line Yj is connected to the Y-axis scanning circuit 3. Further, the other end of each sense line Xi is connected to a diode 4i (4o, 44, . . .
... 4n) to the common X-axis output line 5, and the other end of each sense line Yj is connected to a diode 6j (6o, 6, . . . 6m). It is connected to a common Y-axis output line 7 via. Note that although the following explanation is only about the X-axis, the same applies to the Y-axis. Reference numeral 8 denotes a scanning address signal generation circuit, and by supplying a future scanning address signal to the scanning circuit 2, scanning signals of a constant period are sequentially applied from the scanning circuit 2 to each of the sense lines X0 to Xn. ing.

Reference numeral 9 denotes a pen-shaped coordinate indicator, which is equipped with a coil, an oscillation circuit, etc., and is designed to generate an alternating magnetic field from its tip.

When the coordinate indicator 9 is positioned at an arbitrary point on the tablet 1, an alternating current signal is induced in the sense lines xl-xn in the vicinity of the coordinate indicator 9 by magnetic induction of an alternating magnetic field generated from the coordinate indicator 9.

The induced signal induced on the sense line Xi is
Only when the scanning signal from the scanning circuit 3 is applied to i, it is superimposed on this scanning signal, passes through the diode 4i, and is led out to the output line 5. The induced signal superimposed on the scanning signal is distinguished from the scanning signal by a band P-wave device 10, converted into a DC signal by a rectifier circuit 11 and a low-band P-wave device 12, and further converted into a DC signal by an A-D converter 13. It is converted into a digital signal representing the level of the signal induced on the sense line Xi.

Then, in the maximum value detection circuit 14, each sense line x1~
The maximum value of the induced signal generated at xn is detected, and the maximum value of the induced signal level and the sense line
The induced signal levels generated on the sense lines Xi-1 and Xi+1 before and after i are compared, and based on these values, the curve correction circuit 15 determines the sense line Xi and the sense line Xi at the point indicated by the coordinate indicator 9. -1 or Xi+1 (including on the line) is detected.

Furthermore, this position signal is combined with the above-mentioned scanning address signal (which represents the absolute position of the sense line Xi that produced the maximum value) when the maximum value of the induced signal level was detected, and the adder 16
and the result is output as the position coordinates of the point indicated by the coordinate indicator 9. Many conventionally known coordinate reading devices, such as the Seiden induction type, also scan the sense line (or signal line) to determine the indicated position of the coordinate indicator, similar to the electromagnetic induction type device described above. However, most conventional coordinate reading devices of this type repeatedly scan the entire area on the tablet.

That is, in the illustrated device, the sense line X. From Xn
The scanning up to this point is repeated. Therefore, as the area of the tablet increases, the repetitive scan time for a point on the tablet increases and the data sampling rate decreases. Therefore, in the continuous reading mode in which the coordinate indicator is moved on the tablet and its locus of movement is read at a sampling period by sense line scanning, the moving speed of the coordinate indicator is limited. For example, when writing a signature using a coordinate indicator, the moving speed of the indicator is too fast, making it difficult to accurately read the trajectory of the indicator. One possible solution to this problem is to increase the scanning speed according to the size of the tablet, but there are limitations in terms of the processing time of the guidance signal and the responsiveness of the scanning signal.

In addition, there is a method to reduce the repetitive scanning time by dividing the tablet into multiple areas and using a binary search method in which the position of the coordinate indicator is searched and concentrated from a large scanning area to a small scanning area. However, this method is
This method has drawbacks such as requiring a scanning line for each area of the tablet and complicating the scanning circuit. The scanning method of the present invention is such that, in the continuous reading mode, scanning signals are applied only to sense lines in appropriate partial areas before and after the position indicated by the coordinate indicator as the center, and in addition, as the coordinate indicator moves, The scanning area automatically follows and moves, and by keeping the size of this partial scanning area constant, the sampling period remains constant regardless of the size of the tablet, significantly reducing the repetitive scanning time. It can be shortened to .

FIG. 2 is a block diagram of an embodiment in which the scanning method according to the present invention is applied to the coordinate reading device shown in FIG.

Note that this block diagram shows the configuration regarding the X axis, and the entirety of FIG. 2 corresponds to the scanning address signal generation circuit 8 described above. In FIG. 2, numeral 17 is a counter that supplies a scanning address signal to the scanning circuit 2, and this counter 17 is incremented by a clock pulse from a clock generator 18, and its count output is a scanning address. The signal is updated.

19 is a maximum value detection trigger generation circuit which receives the signal from the maximum value detection circuit 14 and outputs a predetermined trigger signal when the maximum value of the induction signal is detected; this trigger signal is sent to the register 20 and the judgment It is supplied to the circuit 21.

The register 20 stores the scanning address signal output from the counter 17 at the time of receiving the trigger signal from the trigger generation circuit 19.
When the maximum value of the induced signal is detected from the sense line Xi,
The address signal (Xi) of this sense line Xi is stored in the register.

22 is a numerical value setter, and an appropriate numerical value j) set therein is supplied to a subtracter 23.

The subtracter 23 subtracts the above numerical value (j) from the address signal (Xi) stored in the register 20, and outputs an address signal (Xi-j). The determination circuit 21 is
When a trigger signal is supplied from the trigger generator 19 to the determination circuit 21, which determines whether the maximum value is detected during one sense line scan and performs the following control operations, an appropriate delay is performed from that point onward. 0 at the J input terminal of the counter 17 after the time elapses.
A predetermined trigger signal is supplied through the R gate 24, and a gate open signal is supplied to the gate 25.

When a trigger signal is supplied to the J input terminal of the counter 17,
The output from the subtracter 23 is preset into the counter 17 via a gate 26 (assumed to be open, described later),
The scanning address signal output from the counter 17 starts from the aforementioned (Xi-j).

When the gate 25 is opened, a clock pulse from the clock generator 18 is introduced into the M-ary counter 27, and when the M-ary counter 27 has been incremented M times, a carry signal is outputted. Then, on the counter 17 (Xi
-j) is preset until the above-mentioned carry signal is output, that is, while scanning M sense lines from sense line Xi-j, the maximum value of the induced signal is detected,
When the trigger signal from the trigger generator 19 is supplied to the register 20 and the determination circuit 21, the carry signal is supplied to the J input terminal of the counter 17, and the output of the subtracter 23 is preset to the counter 17 again.

Furthermore, if the trigger signal from the trigger generator 19 is not supplied to the determination circuit 21 until the carry signal is supplied to the determination circuit 21, that is, if the sense line Xi-j
If the maximum value of the induction signal is not detected during scanning from to the sense line Xi-j+m, a reset signal is supplied from the determination circuit 21 to the R input terminal of the counter 17, and
The gate 25 is closed under the control of the determination circuit 21. The above operation will be specifically explained using FIG. 3.

Here, the valence j) is set to (4), and the M-adic counter 25 is an octal counter. First, the counter 17 is connected to the sense line X.

Start scanning from. At this time, when the coordinate indicator 9 indicates the XA point, the maximum value of the guiding signal is detected on the sense line X6 closest to the XA point, and then the address signal (X6) is stored in the register 20, and the From vessel 23 (
X6-4)=(X2) is output. Then, when the trigger signal from the determination circuit 21 is supplied to the J input terminal of the counter 17, the counter 17 is preset to (X2), and the counter 17 starts scanning from the sense line X2.
At the same time, the gate 25 is opened and the octal counter 27 starts counting, and when the octal counter 27 has been incremented eight times, a carry signal is output. If the coordinate indicator 9 is moving from point XA to point XB until this carry signal is output, the maximum guidance signal will be reached at sense line X8 during the scan started from sense line The value is detected, and at this time, the address signal (X8) is stored in the register 20, and the subtracter 23 outputs (X8)=(X4).

This address signal (X4) is applied to the sense line X2 at the time when the carry signal is output from the octal counter 27.
The counter 17 is preset at the time when the scanning started from the point reaches the sense line X9.

As a result, the counter 17 scans from the sense line X4 to the sense line Xll. In this way, when the maximum value of the guidance signal is detected, only a partial area consisting of eight sense lines in front and behind that sense line is scanned, and this partial scanning area follows the movement of the coordinate indicator 9. That's what I do.

Here, the scanning signal speed is 10KHz, and the partial area is 8KHz.
In repeated scanning using the sense lines of a book, the number of samples for any one point on the tablet 1 is 2500 points/second, and when the sense line interval is 10 mm, the scanning distance is 200 m/second. Therefore, if it is set to this level, the tracking performance by scanning the partial area will be sufficient for the moving speed of the coordinate indicator 9 in the normal usage mode. Further, when the coordinate indicator 9 is separated from the tablet 1 and the maximum value of the guiding signal is not detected during scanning of the partial area, the counter 17 is reset by the reset signal from the determination circuit 21, and the scanning starts from the sense line XO. is started, the gate 25 is closed, and the M-adic counter 27
does not work, so all sense lines are X. -Xn is scanned. Also, the position indicated by the coordinate indicator 9 is the sense line X.

If the subtraction result in the subtracter 23 is close to , the gate 26 is inhibited by the sign bit of the subtracter 23,
The input to the counter 17 is zero, ie (XO), and when this value is preset to the counter 17, the sense line X. Scanning starts from. Further, as a countermeasure against the case where the indicated position of the coordinate indicator 9 is close to the sense line Xn and the partial scanning area exceeds the sense line Xn, the counter 17
There are methods such as providing an over address bit for the main scan, or resetting the M-ary counter 27 with a carry signal from the counter 17 and presetting the output of the subtracter 23 into the counter 17 at the same time.

As is clear from the above description, the scanning method according to the present invention scans a partial area around the indicated position of the coordinate indicator,
Moreover, since this partial scanning area moves to follow the indicated position, regardless of the size of the tablet,
The sample rate is high and constant, and the coordinates can be read with sufficient resolution even for high-speed handwritten characters such as signature characters.

Moreover, as shown in the embodiment, this system can be realized with a relatively simple circuit configuration using registers, subtracters, M-ary counters, and some gates.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. Fig. 1 is a block diagram showing the basic configuration of an automatic coordinate reading device, Fig. 2 is a block diagram showing details of the present scanning method, and Fig. 3 is a block diagram showing the main scanning method. FIG. XO-Xn...X-ray sense line, YO-Ym...
...Y-axis sense line, 1...Tablet, 2
...X-ray scanning circuit, 5...X-axis output line, 8...Scanning address signal generation circuit, 9...
...Coordinate indicator, 10...Band ▲ wave device, 11
...... Rectifier circuit, 12... Low range ▲ wave generator,
13...A-D converter, 14...Maximum value detection circuit, 15...Curve correction circuit, 16...
...Adder, 17...Counter, 18...
... Clock generator, 19 ... Maximum value detection trigger generation circuit, 20 ... Register, 21 ...
...Judgment circuit, 22...Numeric value setter, 23
...Subtractor, 24 ...0R gate, 2
5, 26...Gate, 27...M-adic counter.

Claims (1)

[Claims] 1 In an automatic coordinate reading device that sequentially scans a large number of sense lines laid on a tablet and detects the indicated position of a coordinate indicator placed on the tablet using the scanning signal, the position of the coordinate indicator on the tablet is detected. In order to perform the detection, there is a detection means for detecting the maximum value of the induced signal induced in the sense line, a storage means for storing the address of the sense line at the time when the maximum value of the induced signal is detected, and a next scan for the address. A scanning method for an automatic coordinate reading device comprising a subtracting means for setting a starting point and a counting means for setting the number of sense lines to be scanned from the scanning starting point.