JPH0368410B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coordinate system for detecting the coordinates of an electromagnetic pen (stylus pen, cursor, etc.) located on a tablet configured by laying conductive wires at a predetermined pitch. This invention relates to a detection device.

[Conventional technology]

A coordinate detection device is a device that outputs the position of an electromagnetic pen placed on a tablet as coordinate values of coordinates set on the tablet based on a signal output from the tablet, and is generally well known. The tablet is constructed by stacking a group of detection lines for the X-axis and a group of detection lines for the Y-axis such that they are orthogonal to each other. Each detection line group was laid at a predetermined pitch.
It has cos and sin lines. One of such detection line groups will be explained using a diagram.

FIG. 3a is a plan view of a group of detection lines for one axis, for example the X-axis. In the figure, 1 is a tablet board made of insulating material, 2 is a COS wire made of one conductor laid on the tablet board 1, and 3 is a SIN wire made of one conductor laid on the tablet base 1. It is a line. The cosine wire 2 and the sinusoidal wire 3 are each laid at a predetermined pitch P, and the cosine wire 2 and the sinusoidal wire 3 are shifted from each other by 1/4 pitch (0.25P).

2c is a cos line compensation loop line laid around the entire cos line 2, and one end of the cos line 2 is located at the point c shown in the figure.
is connected to the above-mentioned cos line compensation loop line.
The cosine compensation loop line 2c is laid 0.3 pitch (0.3P) away from the line forming both terminal edges of the cosine line 2.
3c is a sin line compensation loop line laid around the entire sin line 3, and connected to the sin line at point s. The sin line compensation loop line 3s is laid 0.3 pitch (0.3P) away from the line forming both terminal edges of the sin line 3. T ₂ is the terminal connected to cos wire 2, T _2c
is the terminal connected to the cos line compensation loop line 2c, T ₃
is a terminal connected to the sine wire 3, and T _3s is a terminal connected to the sine wire compensation loop 3s.

When an electromagnetic pen (not shown) is positioned at any point on these detection lines, a voltage is induced in each line accordingly, and this voltage is output from each terminal as a signal for the detection lines. Based on this output, necessary signal processing, calculation, and control are executed, and the position of the electromagnetic pen is detected as a coordinate value (X coordinate value). In addition, the position of the electromagnetic pen in the pitch P can only be determined by the group of detection lines shown in the figure.
Although the coordinate values of the electromagnetic pen cannot be obtained, for example, if you separately lay a selector line on these detection lines and scan it, you can find out which pitch the electromagnetic pen is at, and from this you can obtain the coordinate value. is obtained. In the figure, illustration of this selector line is omitted. In addition, the coordinate detection circuit and calculation means are also based on, for example, Japanese Patent Publication No. 53-34855.
Since this method is known from publications such as No. 1, the description thereof will be omitted.

Similarly, for the Y-axis, a cosine line, a sine line, a cosine compensation loop line, and a sine compensation loop line are wired, and the Y-axis coordinate value of the electromagnetic pen is detected by the same means. This Y-axis detection line group is arranged so as to overlap the illustrated X-axis detection line group so that the cosine lines and sine lines are orthogonal to each other.

Here, the cosine compensation loop line 2c and the sine compensation loop line 3s are installed to improve detection accuracy. That is, the electromagnetic pen has cos line 2 and sin line 3
When the coordinate value is at or near the edge of , the detection error of the coordinate value becomes quite large. The cosine compensation loop line 2c and the sine compensation loop line 3s compensate for this.

FIG. 3b is a graph showing the magnitude of the detection error of the detection line group shown in FIG. 3a. In the figure, the horizontal axis shows the pen position of the electromagnetic pen in correspondence with Figure 3a, and
The value of detection error is plotted on the vertical axis. A shows a detection error curve in which the detection error increases rapidly near both ends of the tablet substrate 1. The value a ₁ on the vertical axis indicates the maximum allowable error, and the position p _t on the horizontal axis indicates the positions of both ends of the tablet substrate 1.
Usually, the part below the value a ₂ , which is slightly lower than the value a ₁ , is used for coordinate detection, and in the figure, the position p ₁ corresponding to the value a ₂ is used.
This corresponds to the portion B ₁ between and position p ₂ . This portion B ₁ is referred to as a valid region, and the other portion (portion where the detection error exceeds the value a ₂ ) B ₂ is referred to as an invalid region. The values detected in the valid area _B1 are adopted as coordinate values, and the values detected in the invalid area _B2 are discarded. Note that B ₃ indicates a compensation loop area formed by the cosine compensation loop line 2c and the sine compensation loop line 3s, and the formation of this compensation loop area B ₃ expands the effective area B ₁ .

[Problem that the invention seeks to solve]

The above-mentioned conventional tablet has the excellent effect that the effective area can be expanded by installing the cosine compensation loop line 2c and the sine compensation loop line 3s. However, on the other hand, since the cosine compensation loop line 2c and the sine compensation loop line 3s are installed, the ineffective area increases and the overall area of the tablet also increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coordinate detection device that solves the problems of the prior art described above and can enlarge the effective area without increasing the invalid area.

[Means for solving problems]

In order to achieve the above object, the present invention provides that, at the end in the pitch direction of a detection line group laid at a predetermined pitch, another detection line group having a pitch smaller than the pitch of the detection line group is placed next to the previous detection line group. A coordinate value obtained based on a signal output from the other detection line group when it is detected that the electromagnetic pen is located on the other detection line group when the electromagnetic pen is arranged so as to overlap the detection line group. It is characterized in that it is read as the coordinate value of the electromagnetic pen.

[Effect]

When it is detected that the electromagnetic pen is on the other detection line group, a signal is extracted from the output terminal of the other detection line group, and the necessary calculations and controls are performed based on this signal to determine the coordinate value. The coordinates are calculated and read as the coordinates of the electromagnetic pen.

〔Example〕

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

FIG. 1a is a partially cutaway plan view of a tablet 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. 3a are given the same reference numerals, and explanations thereof will be omitted. There is a third board on the tablet board 1.
Similar to the one shown in Figure a, the cos line 2 and the sin line 3 are laid at a pitch P and shifted by 1/4P from each other, and the cos line compensation loop line 2c and
A sin line compensation loop line 3s is also laid. Reference numeral 5 indicates a detection line group composed of these lines, and this detection line group is referred to as a main detection line group. Tablet board 1
The dimensions and the wiring positions of the main detection line group 5 on the tablet substrate 1 are the same as those shown in FIG. 3a.

6 is a thin insulating layer provided on the main detection line group 5. 7 is an insulating layer 6 at both ends of the tablet substrate 1 (both ends in the pitch direction of the main detection line group 5).
A sub-detection line group is placed above, overlapping the end of the main detection line group 5. Since the configurations of the sub-detection line groups 7 at both ends are the same, only the configuration of one sub-detection line group 7 (the one at the right end in the figure) will be explained, and the illustration and explanation of the other sub-detection line group 7 will be omitted. .

8 is a cosine line of the sub detection line group 7, and 9 is a sine line. These cos wires 8 and sin wires 9, like the cos wires 2 and sin wires 3 of the main detection line group 5, are constructed by arranging one conducting wire in a meandering manner. The pitch of the cosine line 8 and the sine line 9 are each P', and the cosine line
The line 8 and the sin line 9 are arranged offset from each other by 1/4P'. The pitch P′ is the cosine line 2 and sin of the main detection line group 5.
It is smaller than the pitch P of line 3 and has an appropriate value, for example,
It is selected from 1/2P to 1/4P. 8c is a cosine compensation loop line, 9s is a sine compensation loop line,
It is connected to the end line of the cosine line 8 and the end line of the sine line 9 at points c' and s', respectively, and the distance to each end line is selected to be 0.3P'. T ₈ is a terminal connected to cos line 8, T ₉ is a terminal connected to sine line 9, T _8c is a terminal connected to cos line compensation loop line 8c, T _9s is connected to sine line compensation loop line 9s. It is a terminal that has been connected. In this embodiment, the sub-detection line group 7 is provided only for the X-axis.

When the electromagnetic pen is positioned at any point on the sub-detection line group 7, a voltage is induced in each line accordingly, and this voltage is output from each terminal as a signal on the sub-detection line group 7. The subsequent processing is exactly the same as the processing of the signals of the main detection line group 5, and the coordinates of the electromagnetic pen in the sub detection line group 7 can be detected by such processing. Then, the sub-detection line group 7 is set so that the coordinates of the sub-detection line group 7 match the coordinates of the main detection line group 5.
It is obvious that by adjusting the overlap with the main detection line group 5, the coordinate values of the sub detection line group 7 can be expressed as the coordinate values of the main detection line group 5.

FIG. 1b is a graph showing the magnitude of the detection error of the main detection line group 5 and the sub-detection line group 7 shown in FIG. 1a. In the figure, the horizontal axis shows the pen position of the electromagnetic pen, and the vertical axis shows the detection error. A is the detection error curve of the main detection line group 5, which is the same as that shown in FIG. 3b;
A' is a detection error curve of the sub-detection line group 7, respectively. The error values a ₁ and a ₂ are the same as the values a ₁ and a ₂ shown in FIG. 3b. Also, the positions p _t , p ₁ , p ₂ are also shown in Fig. 3b.
Indicates the same position as each position p _t , p ₁ , p ₂ shown in . p _1t ,
p _1c , p _2t , and p _2c are positions corresponding to the value a ₂ on the detection error curve A′. Of each of these positions, the position
p _1t is the position of the left side sub-detection line group 7 on the tablet board edge side in Fig. 1a, position p _1c is also the position on the center side of the tablet board, and position p _2t is the right side sub-detection line group The position _p2c at the end of the tablet board 7 is also located at the center of the tablet board. An area B ₄₁ between positions p _1t and p _1c and an area B ₄₂ between positions p _2t and p _2c are effective areas for detection by each sub-detection line group 7, respectively.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG. First, it is determined whether the electromagnetic pen is located in the sub-detection line group 7 (step S ₁ ). This determination is made based on whether a voltage of a predetermined level or higher is induced at the terminals of the sub-detection line group 7. If the electromagnetic pen is not located in the sub detection line group 7, it is determined in the same way whether or not there is an electromagnetic pen in the main detection line group 5 (step S ₂ ). If the electromagnetic pen is not on the main detection line group 5, it is determined that there is no electromagnetic pen on the tablet, and the procedure returns to the start. If it is determined that the electromagnetic pen is on the main detection line group 5, the coordinates are detected based on the output voltages of the main detection line group 5 and the Y-axis detection line group (step _S3 ).
Next, based on these coordinate values, it is determined whether the X-axis coordinate value and the Y-axis coordinate value are in the valid area (corresponding to the valid area _B1 shown in FIG. 3b) (step S ₄ ), and the valid area is determined. If so, output the coordinate values detected in step _S3 (step _S5 ). If it is not in the valid area, the procedure returns to the start.

On the other hand, in step _S1 , if it is determined that the electromagnetic pen is on the sub-detection line group 7, the sub-detection line group 7
Based on the output voltage from the terminal, X-axis coordinate detection is performed using the sub-detection line group 7 (step S ₆ ). In this case, which side of the sub-detection line group is on is known when checking the output voltage in step _S1 . Next, it is determined whether the X-axis coordinate value detected in step S ₆ is within area B ₄₁ or area B ₄₂ shown in FIG. 1b (step S ₇ ),
If it is within the area, the Y-axis coordinates are detected using the Y-axis detection line group (S ₈ ). Then, it is determined whether the coordinate value is in the valid area (corresponding to valid area _B1 shown in Figure 3b) (step _S9 ), and if it is in the valid area, it is detected in step _S6 . Output the X-axis coordinate value and the Y-axis coordinate value detected in step _S8 (step
_S5 ). If it is determined in step _S9 that the Y-axis coordinate value is not in the valid area, the procedure returns to the start.

Furthermore, in step _S7 , if it is determined that the X-axis coordinate value is not in the effective area (area B ₄₁ or area B ₄₂ ), this time the X-axis coordinate value is on the center side of the sub-detection line group 7, that is, the Position p _1c side or position p _2c shown in Figure 1 b
It is determined whether it is on the side or on the end side, that is, on the position p _1t side or on the position p _2t side (step S ₁₀ ).
If it is determined that the electromagnetic pen is located on the center side, the electromagnetic pen is within the effective area of the main detection line group 5, as is clear from _FIG . Detection of the X-axis and Y-axis by the line group 5 The Y-axis coordinates are detected by the line group. On the other hand, if it is determined in step _S10 that the X-axis coordinate value is on the end side, no coordinate detection is performed and the procedure returns to the start.

In this way, in this example, the sub-detection line group is overlapped with the end of the main detection line group, and the pitch of the sub-detection line group is made smaller than the pitch of the main detection line group, so that the area of the tablet can be reduced without increasing. It is possible to expand the effective area and reduce the ineffective area. To further explain this with reference to FIG. 1b, the effective area B ₁ ' is located at positions p ₁ to _{p 1t and} positions p ₂ to p _2t from the conventional effective area B 1.
, and the invalid area B ₂ ' is made smaller than the conventional invalid area B ₂ by that amount.
Moreover, the overall dimensions of the tablet are exactly the same as those of the conventional tablet.

In addition, in the description of the above embodiment, an example was explained in which the sub-detection line group is arranged only on the It's okay. Furthermore, depending on the object of use, the sub-detection line group may not be arranged at both ends, but may be arranged only at one end.

〔Effect of the invention〕

As described above, in the present invention, a sub-detection line group with a pitch smaller than the pitch is arranged at the end of the main detection line group in the pitch direction so as to overlap the main detection line group, and the electromagnetic pen Since the coordinates are read by the sub-detection line group when the tablet is on the line group, it is possible to reduce the invalid area of coordinate detection and expand the effective area without increasing the area of the tablet.

[Brief explanation of drawings]

FIG. 1a is a partially cutaway plan view of a tablet of a coordinate detection device according to an embodiment of the present invention, and FIG.
Detection error characteristic curves of the main detection line group and sub-detection line group shown in Figure a, Figure 2 is a flowchart explaining the operation of the device shown in Figure 1A, Figure 3A is a plan view of a conventional tablet, FIG. 3b is a detection error characteristic curve of the main detection line group shown in FIG. 3a. 5... Main detection line group, 7... Sub detection line group, 8...
cos line, 9...sin line.

[Claims]

1. A digitizing device for digitizing the coordinates of a point on a digitizing working surface having conductive means for receiving capacitively coupled transducer signals, comprising: (a) a conductive member having a conductive end; a transducer; (b) means disposed on the transducer for generating an AC signal and applying the signal between first and second ungrounded conductors; and (c) disposed on the transducer. (d) a virtual ground conductor having a capacitance larger than that of the conductive member;
means for applying an AC signal; (e) means for measuring the level of a signal capacitively coupled to the conductive means from the conductive end; and (f) the measured signal. processing levels to determine the coordinates of the conductive end of the transducer;