JPH02190919A - Coordinate detector - Google Patents

Abstract

PURPOSE:To detect coordinates even at the end part of a tablet and to expand the effective area of coordinate detection by correcting the operation value of a position in a pitch when a indicator is included in the end part area. CONSTITUTION:At the time of detecting coordinates, an area deciding means always decides whether the indicator is included in the end part area or not, and when the indicator is not included in the area, outputs the detected coordinate value as it is. When the indicator is included in the area is decided, the operation value of the position in the pitch of a conductor is corrected by a correction value through a correcting means and the coordinate value calculated by the corrected value is outputted as a detected coordinate value. Consequently, coordinate detection can be attained even at the end part of the tablet and the effective area of the coordinate detection can be expanded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a coordinate detection device using an electromagnetic induction method.

[Conventional technology]

A coordinate detection device is a device that detects the coordinate values of a position on a tablet when a position on a tablet is specified using a pointing device such as an electromagnetic pen or a cursor. Such a coordinate detection device is
For example, it is disclosed in Japanese Unexamined Patent Publication No. 159191/1983 and is well known. The outline of the coordinate detection device described in the publication will be explained below using figures.

FIG. 5 is a block diagram of a conventional coordinate detection device, in which 1 is an oscillator, 2 is a counter that reduces the frequency of the oscillation pulse of the oscillator 1, and 3 is a block diagram of a conventional coordinate detection device. This is a filter with a sine wave current of . 4 is! This is an excitation coil built into an indicating device such as a magnetic pen, and is excited by the 1gl flow supplied from the filter 3.

5 is a tablet. Tablet 5 has Y-axis and Y-axis gL'4! A is wired. The Y-axis conductor consists of four conductors, the first conductor is wired in a meandering manner at a pitch of P, and the second conductor is wired with a P/4 pitch shift from the first conductor. . Furthermore, the third conductor has a pitch Q
The fourth conductive wire is laid out in a meandering manner in the same direction as the first conductive wire, and the fourth conductive wire is shifted by a Q/4 pitch with respect to the third conductive wire. 1st 2! ! If the total number of pitches of the line is n, then the pitch P and the pitch Q are in the relationship nP=(n-1)Q.

The Y-axis conducting wire is also the same as the X-axis circumferential conducting wire except that the wiring direction is different by 90 degrees.

5X and 5Y indicate four conductive wires for the Y-axis and four conductive wires for the Y-axis, respectively.

6 is Y by a command signal from a data processing device which will be described later.
The first and second conductive wires for the axis, the third and fourth conductive wires for the Y-axis, the first and second conductive wires for the Y-axis, and the third conductive wire for the Y-axis. This is a switching device that sequentially switches the first and fourth conducting wires and inputs the output signal of each of these conducting wires. 7 and 8 are amplifiers that amplify the signal input from the switch 6; 9 is a differentiator that differentiates the signal on one of the conductors, for example, the first conductor of the first conductor and the second conductor; and 10 is a differentiator This is an adder that adds the output signals of the amplifier 8 and the differentiator 9.

A waveform converter 11 converts the output signal of the adder 10 into a pulse signal having the same phase as the output signal of the adder 10. A phase comparator 12 detects the phase difference between the rising edge of the pulse output from the counter 2 and the rising edge of the pulse output from the waveform converter 11. Reference numeral 13 denotes a data processing device that calculates coordinate values and performs other processing and control based on the phase difference detected by the phase comparator 12.

The coordinate detection operation of the pointing device with such a configuration is detailed in the above-mentioned publication, so the explanation will be omitted.

[Problem to be solved by the invention]

In the above-mentioned conventional coordinate detection device, as described above, four X-axis circumferential conductors and four Y-axis circumferential conductors are each arranged in a meandering manner on the tablet 5.

The overall shape of the cloth of each conducting wire is approximately rectangular, consisting of four sides: the starting side of the conducting wire, the ending side of the conducting wire, and both sides formed by folding back ends of the conducting wire.

Among such conductive wires, the first conductive wire and the second conductive wire for the Y axis will be explained with reference to the drawings.

Figure 6 is a wiring diagram of the two conductors in the X-axis conductor.

be. In the figure, 5X+ is the first conducting wire, 5Xz is the second conducting wire, 11.11' is both terminals of the first conducting wire 5x, 12.
12' indicates both terminals of the second conductor vA5Xt. When the excitation coil 4 of the indicating device is placed in the wiring shown, the terminal 11
．． A voltage corresponding to the position of the excitation coil 4 is outputted to the switching device 6 from the terminals 11' and 12°12'.

In the figure, the position of the excitation coil 4 is on the virtual line B during wiring, and! It is a position at a distance r from the starting position of the second pitch 4 of the line sx.

FIG. 7(a) is a waveform diagram of the output voltages E+ and Et of the conductors &isx+ and sxt when the excitation coil 4 is located on the imaginary line B, and the output voltage waveform has a sine waveform as shown in the figure. Become. Moreover, FIG. 7(b) shows such an output voltage E1
．． 6 is a waveform diagram of the number of pulses output from the phase comparator 12 as a result of processing Et by the circuit shown in FIG. 5. FIG. The number of pulses increases linearly in proportion to the distance from the pitch start position of the conducting wire 5X to the pitch end position (start position of the next pitch), and the waveform is the same for each pitch. In addition,
The coil 4
It is determined which pitch the position is on.

By the way, coil 4 leads to lx,,X! If it is near the folded part of , for example on the virtual lines A and C shown in FIG. 6,
A so-called edge effect occurs and the outputs of conductors 5X+ and 5Xt are E,,E! This causes a distortion in the number of pulses. FIGS. 7(C) and (d) show the output voltage E when the coil 4 is placed on the virtual vAA or the virtual line C,
, Et and the number of pulses. In this case, as shown in the figure, the output voltages E, E2 have a distorted waveform different from a sine waveform, and the waveform of the number of pulses has undulations as shown in the figure. Therefore, virtual line A.

Near C, that is, conductors 5XI, 5X! The detected coordinate values near the folded portion (end) of the image will be inaccurate, and this area will eventually become an area that cannot be used for coordinate detection.

Therefore, the effective area in which coordinates can be accurately detected is significantly limited over the entire area where the conducting wires are laid.

The purpose of the present invention is to solve the problems in the above-mentioned prior art,
It is an object of the present invention to provide a coordinate detection device that can perform coordinate detection even at the edge of a tablet and can further expand the effective area of coordinate detection.

[Means to solve the problem]

In order to achieve the above object, the present invention includes an indicating device that is excited at a predetermined frequency, a conductive wire that is arranged in a meandering manner at a predetermined pitch in a first axis direction, and a conductive wire that is perpendicular to the first axis. A coordinate detecting device comprising: a tablet made up of conductive wires arranged in a meandering manner at a predetermined pitch in the axial direction of the second axis; and calculating means for calculating the position of the indicating device on the tablet based on the output of the tablet. , area determining means for determining whether or not the position of the pointing device on the tablet is in an edge region that causes an error in the calculated value of the calculating device; The present invention is characterized by further comprising a correction means for correcting the calculated value of the position of the pointing device within the pitch by a correction value corresponding to the calculated value.

[For production]

When detecting coordinates, the area determination means always determines whether or not the pointing device is in the edge area, and if it is not in the edge area, outputs the detected coordinate values as they are.

Also, if it is determined that the indicating device is in the edge area,
The correction means corrects the calculated value of the position within the pitch of the conducting wire using the correction value, and outputs the coordinate value calculated based on the corrected value as the detected coordinate value.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of a coordinate detection device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 5 are given the same reference numerals, and explanations thereof will be omitted. 15 is a data processing device corresponding to the data processing device 13 shown in FIG. The other configurations are the same as those shown in FIG. The data processing device 15 includes an input/output device (Ilo) 15a that inputs and outputs data or signals to and from other parts of the circuit, necessary calculations,
It is composed of a CPU 15b that performs control, a ROM 15C1 that stores processing procedures of the CPU 15b, a RAM 15d that stores results of control, and an interface 15a that connects with external circuits. 15d+ is RAM
15d indicates a correction value storage section, and 15d2 indicates a specified value storage section within the RAM 15d.

Hereinafter, the correction values and specified values stored in each of these storage units 15d+ and 15dt will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a waveform diagram with the same number of pulses as shown in FIG. 7(d). In both this figure and the waveform diagram shown in FIG. 7(d), the undulations are exaggerated for ease of understanding. This undulation is caused by the
It is the same at each pitch on the same imaginary line in the axial direction, and
The closer the virtual line is to the edge, the slightly thicker the undulations (but the period of the undulations is the same.The same applies to the Y-axis direction.A waveform with such undulations is shown in Fig. 2). The number of pulses at the point where it intersects with the true value (the point that becomes the true value) shown by the broken line is set as Or ``l r nt + ''2, and the number of pulses 0 or more and n1 is classified as Ao, the number of pulses that are n+ or more and less than n8 is classified as A1, and n= Those above and below n1 are defined as category A1, and those above n8 are defined as category A8. Then, go to category 〇.

The correction value for the pulse number of A is -411 category A+, A
The correction value for the number of pulses of s is defined as Δn. Note that these numerical values nl-n, . The determined correction values Δn1-Δn are stored in the correction value storage unit 15d for each category.

Next, the specified values will be explained. FIG. 3 is a plan view of the tablet 5, and Y, □ are virtual lines A shown in FIG.
YMI is the coordinate value Y, which is the coordinate value of the Y axis corresponding to the virtual line C, 41 or less, and the coordinate value YN! With the above coordinate values, an error occurs in the detected X-axis coordinate value due to fluctuations in the number of pulses caused by the edge effect of the folded portion of the conducting wire. In exactly the same way, errors occur in the detected Y-axis coordinate values for coordinate values below the coordinate value X□ and above the coordinate value XN2. These coordinate values X s + , X N ! , YNl,
Y s □ is also obtained by actual measurement like the correction value.

These coordinate values are referred to as specified values, and these specified values are respectively stored in the specified value storage section 15d2.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG. First, the number of pulses (Y-axis pitch P) output from the phase comparator I2.

The number of each pulse obtained from the output of the conductor Q, the pitch P of the Y-axis, and the number of pulses obtained from the output of the conductor Q) are read (step S+), and the data processing device 15 reads the Y-axis,
Calculate the Y-axis coordinate value. Procedure Sl, S! The processing is the same as the conventional processing.

Next, the specified values YN, , Y, □ are read from the storage unit 15d* (step S3), and these are compared with the coordinate value Y calculated in step S2 (step S4).

If the coordinate value Y is not (YNI < Y < YNz),
That is, if it is outside the effective area (at the end), first, it is determined to which of the categories A0 to A shown in FIG. 2 the number of pulses of the Y-axis pitch P obtained in step S1 belongs (
Procedure SS). Then, the correction value is read out from the correction value storage unit 15dl according to the determined classification (step S), and this correction value is added to the previous number of pulses (if the correction value is -Δn, it is subtracted). Obtain the number of pulses corrected by (step 57) 0 Next, the same processing as steps S to S7 above is performed for the number of pulses at pitch Q on the Y axis (step Ss). Through the processing of steps st and ss, the corrected pulse numbers of the Y-axis pitches P and Q when the indicating device is at the end are obtained, and the correct coordinate value X is calculated from these pulse numbers (procedures S1°). In addition, in the process of step S4, the coordinate value Y is within the range of (Y□<Y<YN2),
That is, if it is determined that it is within the valid area, step St
The coordinate value X obtained in is determined as the correct coordinate value (procedure S+o) - The same process as the above child 1 @ S, ~S1° is performed from the output of the conductor at each pitch P and Q on the Y axis. The number of pulses obtained is also determined (steps S, I), and as a result, if the indicating device is in the Y-axis effective area, the coordinate value Y obtained in the process of step S8 is , the corrected coordinate value Y is determined as the Y-axis coordinate value. These determined coordinate values X and Y are output to the outside via the interface 15e (Step S, □)
.

In this way, in this embodiment, it is determined whether or not the position of the indicating device is at the edge, and when the position of the indicating device is at the edge, the number of pulses is corrected using a predetermined correction value. Coordinate detection can be performed without any problems, and the effective area for coordinate detection can be expanded.

In addition, in the explanation of the above embodiment, one absolute value Δn was used as an example of the correction value, but it is also possible to further subdivide one peak of the detected pulse number undulation and assign correction values with different absolute values to each peak. It is also possible to apply this method to obtain more accurate coordinate values. Also, the end fiJ! The area can also be divided into a plurality of sections, and the correction values can be changed according to each section, thereby making it possible to obtain even more accurate coordinate values. Furthermore, in the description of the above embodiment, 1
Although the description has been given by exemplifying a type of coordinate detection device that uses four conductive wires for one axis, the present invention is not limited to this, and the coordinate detection device uses means for detecting the number of pulses! If so, it is applicable.

〔Effect of the invention〕

As described above, in the present invention, when the indicating device is in the edge area, the calculated value of the position within the pitch is corrected, so coordinates can be detected even at the edge of the tablet, and the coordinates can be detected even at the edge of the tablet. The effective detection area can be expanded.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a coordinate detection device according to an embodiment of the present invention, Fig. 2 is a waveform diagram of the number of pulses within one pitch, Fig. 3 is a plan view of the tablet, and Fig. 4 is shown in Fig. 1. A flowchart explaining the operation of the device, FIG. 5 is a block diagram of a conventional coordinate detection device, FIG. 6 is a wiring diagram of a tablet, and FIGS. 7(a) and (b). (c) and (d) are waveform diagrams of the output voltage and the number of pulses in the effective area and edge area on the tablet. ４・・・・・・・・・Exciting coil, ５・・・・・・・・・
・Tablet, 5X, 5X+, 5Xz, 5Y...
. . . i-line, 15 . . . data processing device, 15d . . . RAM, 15d. ......Correction value storage section, 15d2...
...Standard value storage section Fig. 2 Fig. Fig. Fig. 2

Claims (4)

[Claims] (1) An indicating device that is excited at a predetermined frequency, a conductive wire arranged in a meandering manner at a predetermined pitch in the direction of a first axis, and a conductor wire arranged in a meandering manner at a predetermined pitch in the direction of a second axis orthogonal to the first axis. In a coordinate detection device comprising a tablet made of conductive wires arranged in a meandering pattern, and calculation means for calculating the position of the pointing device on the tablet based on the output of the tablet, the position of the pointing device on the tablet is area determining means for determining whether or not a position is in an end region that causes an error in the calculated value of the calculating means; A coordinate detection device comprising a correction means for correcting a calculated value by a correction value corresponding to the calculated value. (2) In claim (1), the area determining means includes a first area determination unit that determines the end area in the first axial direction based on a predetermined value of the coordinate value in the second axial direction. It is characterized by being comprised of a determining means and a second determining means that determines the end area in the second axial direction based on a predetermined value of the coordinate value in the first axial direction. Coordinate detection device (3) In claim (2), a plurality of the specified values are set for each of the opposing end areas, and the correction value is:
A coordinate detection device characterized in that the coordinate detection device is set according to a plurality of predetermined values. (4) The coordinate detection device according to claim (1), wherein a plurality of the correction values are set for one of the pitches.