JPS62117026A - Coordinate detector - Google Patents

Abstract

PURPOSE:To detect the coordinates with high accuracy by detecting the position of a contact point by means of two linear electrodes distant from the linear electrodes excepting the specific linear electrode even through the contact point is set close to said specific linear electrode. CONSTITUTION:The currents IA and IB flowing through the 2nd detecting resistances 6a and 6b are adversely proportional to the resistance value R1 of the resistance film formed between a linear electrode 4b and a contact 8 and the resistance value R2 of the resistance film between a linear electrode 4d and the point 8 respectively. While the distance from the electrode 4b is proportional to the current ratio IB/(IA+IB). A detection error is produced when the contact 8 is set at a position near the electrode 4b and 4d. In such a case, a current value discriminating circuit 9 detects the value of the current IA or IB flowing the the resistance 7a or 6b. Then the selected two linear electrodes are shifted to 4c-4e or 4a-4c from 4b-4d.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coordinate detection device, and in particular, a coordinate detection device that detects the position of characters, figures, etc. drawn on a tablet input panel, etc., and outputs it to another display device, etc. The present invention relates to a coordinate detection device.

[Conventional developments and problems to be solved by the invention] Conventionally, many of these types of coordinate detection devices have been based on a surface electrode resistive sheet method because they can detect coordinate positions in two directions simultaneously and the circuit is simple. has been adopted.

FIG. 5 is a perspective view schematically showing the main parts of a conventional coordinate detection device, in which 11 is a constant current power supply, 13 is a first resistance plate, 1
4 is a second resistance plate.

The first resistance plate 13 has flexibility, and has first resistor plates at both ends thereof.
electrodes 13a and 13b are provided in parallel. Further, second electrodes 14a are provided at both ends of the second resistance plate 14 so as to be perpendicular to the first electrodes.

14b are provided in parallel. A resistive film is applied to each of the first resistive plate 13 and the second resistive plate 14, and the first resistive plate 13 and the second resistive plate
A gap is provided between the resistor plate 14 and the resistor plate 14 .

By pressing one point of the first low resistance plate I3, the first resistance plate 13 comes into contact with the second resistance plate 1.4 at the pressed point. . Due to this pressed contact point, the current flowing from the constant current power supply 11 is transmitted to the first detection resistors 12a, 12b electrically connected to the first electrodes and the first electrodes 13a, 1.
3b to the first resistor Fi13, and through the pressed contact point to the second low resistance plate 14. Furthermore, the current flows through the second electrodes 14a, 14b and the second detection resistor 1 electrically coupled to the second electrodes.
5a.

15b and is grounded.

In this conventional example, the first detection resistor 12b (12a
) and the current 1b(ia) flowing through the second detection resistor 15b (15a), and fd(ic), the position on the first resistor plate 13 and the second resistor plate 14 are determined. The position at is detected. That is, the ratio ib/(ia + ib
) is proportional to the position in the X direction of the pressed contact point perpendicular to the first electrodes 13a, 13b, and similarly the ratio id/of the currents ic, id flowing through the second detection resistors 15a, 15b. (ic + id) is the second electrode 14a, 1
4b, and since the first electrode and the second electrode are perpendicular to each other, the position of the pressed contact point in the Cartesian coordinate system is detected. It is something that can be done.

However, the accuracy of the coordinates detected by this conventional example is determined by the uniformity of the resistive film applied to the first low resistance plate 13 and the second resistive plate 14. The conventional example cannot detect coordinates with high precision, and when the device is enlarged, the accuracy further deteriorates, which is a major obstacle in increasing the size of the coordinate detection device.

FIG. 6 is a configuration diagram showing the main parts of another conventional coordinate detection device, in which 16a to 16f are line electrodes for Y direction detection, 17a
1'N are line electrodes for X direction detection, 18a and 18b are resistors for Y direction detection, and 218.21b are X direction detection resistors.

The coordinate detection device shown in FIG.
This is described in Japanese Patent No. 5, and improves the coordinate accuracy of the conventional example shown in FIG. This coordinate detection device is the first low-drag plate 3 of the conventional coordinate detection device shown in FIG.
A plurality of line electrodes parallel to the first electrodes 13a and 13b are provided on the second resistance plate 14, and a plurality of line electrodes parallel to the first electrodes 13a and 13b are provided on the second resistance plate 14.
A plurality of line electrodes parallel to 4a and 14b are provided, and coordinates are detected by sequentially selecting two adjacent line electrodes using switch means for each of the plurality of line electrodes.

That is, a plurality of parallel Y-direction detection line electrodes 16a are provided on the resistance film of each resistance plate.

16 b, 16 c, 16 d, 16 e
, 16 f and X direction detection line electrodes 17a, 17
b, 17c, 17d, 17e, and 17f are orthogonal to each other, and the Y-direction detection line electrodes 16a to 17f are orthogonal to each other.
16" are connected by sequentially selecting two adjacent line electrodes by the switch means 19 for detecting the Y direction, and similarly, the line electrodes 17a to 17f for detecting the X direction are connected to each other by the switch means 20 for detecting the X direction. Two wire electrodes are selected and connected in sequence.Then, the current from the constant current power source 27 passes through the Y direction detection resistors 18a and 18b, and connects the Y direction selected sequentially by the Y direction detection switch means 19. The current reaches two adjacent line electrodes of the direction detection line electrodes and reaches one of the resistance plates.Furthermore, the current flows through the pressed contact point to the other resistance plate, and the Y direction detection switch means The X-direction detection switch means 2 has the same function as 19.
The X-direction detection resistors 21a, 2 pass through the two adjacent line electrodes of the X-direction detection line electrodes sequentially selected by
1b and is grounded.

When the two adjacent wire electrodes sequentially selected by the Y-direction detection switch means 19 and the X-direction detection switch means 20 are connected,
The current 1d flowing through the X direction detection resistor 18b and the X
By measuring the current 1b flowing through the direction detection resistor 21b, it is possible to specify the block containing the pressed contact point, and furthermore, as explained with reference to FIG. 5, the position of the contact point in the block can be determined. Coordinates can also be detected.

FIG. 7 is an equivalent circuit diagram of a part of FIG. 6, where 22 is a contact point and 'I+'2 is the resistance value of the resistive film.

FIG. 7 shows a case where the contact point 22 is located between the X-direction detection line electrodes 17a and 17b in the X direction, r,
is the resistance value of the resistive film between the line electrode 17a and the contact point 22, and similarly, rt is the resistance value of the resistive film between the line electrode 17b and the contact point 22. Currents 1a and I flowing through X direction detection resistors 21a and 21b
b, the position in the X direction of the contact point 22 between the adjacent line electrodes 17a and 17b is i/(Ia +
Ib) can be obtained from the formula. In fact, the current ([a
+Ib) is supplied from the constant current power supply 27, so the
The position in the X direction between the line electrodes 17a and 17b can be specified simply by measuring the current rb flowing through the direction detection resistor 21b. However, the currents 1a and Ib include the X-direction detection resistors 21a and 21b. If the resistance value of these X-direction detection resistors 212.21b is "., r0', Ib rl +r.

[a+Ib rl +rz+ (retro
+).

Here, the resistance value r of the X direction detection resistors 21a and 21b is
. +r0' is the resistance value r1. of the normal line resistance film. Since it is minute compared to rz, almost no error occurs even if the coordinates of the contact point 22 are calculated from lb/(Ia + Ib) while ignoring the resistance value rO+ro'. However, the contact point 22
When the position is near either of the line electrodes 17a, 17b, the resistance value ro+ro' of the X-direction detection resistors 21a, 21b cannot be ignored, and the coordinate 1b/(Ia+Ib) of the contact point 22 If it is calculated from , a large error will occur. Figure 8 shows this Ib/ (Ia+Ib)
This is a graph in which the vertical axis is the value of , and the horizontal axis is the distance in the X direction between the line electrodes 17a and 17b.As is clear from the figure, the contact point 22 is the line electrode 17a.

17b, it will be understood that the proportional relationship does not hold.

[Means and effects for solving the problems] The present invention has been made in view of the above-mentioned problems, and provides a novel coordinate detection device, in which a plurality of parallel line electrodes are connected to a resistive film. a first resistive plate formed on the resistive film; a second resistive plate having a plurality of parallel line electrodes orthogonal to the plurality of line electrodes of the first resistive plate formed on the resistive film; a first switch means for sequentially selecting two wire electrodes separated by at least one wire electrode from the plurality of wire electrodes of the resistor plate;
second switch means for sequentially selecting two wire electrodes separated by at least one wire electrode from the plurality of wire electrodes of the resistor plate; and a second switch means for sequentially selecting two wire electrodes separated by at least one wire electrode from the plurality of wire electrodes of the resistor plate; current value determining means for detecting and determining whether the detected current value is within a desired range; Determine whether the position is near the arbitrary line electrode, and if the contact point is near the line electrode,
At least one of each of the plurality of wire electrodes formed on the first resistance plate and the second resistance plate is arranged so that the wire electrode is not electrically coupled to the detection resistor. By sequentially selecting two line electrodes separated by a line electrode, the accuracy of detecting coordinates in the vicinity of the line electrodes is improved.

〔Example〕

Embodiments of the coordinate detection device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view schematically showing the main parts of an embodiment of the coordinate detection device according to the present invention, and FIG. 2 is a partially enlarged view of FIG. Second resistance plate, 4a-4h
5 is a wire electrode, 5 is a second switch means, 6a and 6b are second
The detection resistor 9°9' is a current value discrimination circuit.

A resistive film is coated on the first resistive plate 3, and the resistive film has a plurality of parallel line electrodes 3a, 3b.

3c, 3d, 3e, 3r, and 3g are formed.

The line electrodes 3a to 3g are switched to 1 by the first switch means 2.
Two wire electrodes separated by one wire electrode are sequentially selected i'j5° and connected to one end of each of the first detection resistors 1a or Ib. Further, the other ends of the first detection resistors 1a and lb are coupled to a constant current power source 7. Similarly, a resistive film is applied to the second resistive plate 4, and the resistive film has a plurality of parallel line electrodes 4a, 4b, 4c.
, 4d.

4e, 4F, 4g, and 4h are formed. The wire electrode 4
a to 4h are orthogonal to the line electrodes 3a to 3g, and the second switch means 5 sequentially selects two line electrodes separated by one line electrode, and performs the second detection. It is configured to be connected to one end of each of the resistors 6a or 6b. Further, the second detection resistor 6a
, 6b are grounded.

The current value discrimination circuit 9 includes the second detection resistors 6a and 6b.
are connected to one end of each of the second detection resistors 6a and 6b, and measure the current flowing through the second detection resistors 6a and 6b to detect the coordinates of the pressed contact area and to determine whether the current value is within a desired range. This is to determine whether there is. A similar current value discrimination circuit 9' is also connected to the first detection resistors 1a and lb.

Here, a plurality of wire electrodes 3a to 3g and 4a to 4h on the first resistance plate 3 and the second resistance plate 4 can be formed as necessary, but if the number of the wire electrodes is increased, Of course, the accuracy of coordinate detection can be further improved.

Furthermore, although the numbers of line electrodes formed on the first resistance plate 3 and the second resistance plate 4 do not need to be the same, it is preferable that the gap between adjacent line electrodes be constant.

Next, the operation of the second switch means 5 will be explained with reference to FIG.

The second switch means 5 has switch terminals A-F, C-
Select the second wire electrodes 4a, 4b like H, E-J.
, 4c, 4d, 4e, 4a-4c, 4b-4d, 4
Two wire electrodes separated by one wire electrode, such as cm4e, are selected one after another and connected to one end of the second detection resistor plates 5b and 5a, respectively.

FIG. 3 is an equivalent circuit diagram when 4b to 4d are selected from the 20th cotton electric scraper 4a to 4e, and 8 is a contact point due to suppression. The second detection resistor 6a.

The current IA flowing through 6b, 1. is a value that is inversely proportional to the resistance value R1 of the resistive film between the line electrode 4b and the contact point 8 and the resistance value Rz of the resistive film between the line electrode 4d and the contact point 8. The distance from 4b is proportional to the current ratio +s/(rA+In). When the contact point 8 is near the line electrode 4b or 4d, an error similar to that of the coordinate detection device shown in FIG. 6 will occur, but if the contact point 8 is near the line electrode 4b or 4d, 4b or 4d, the current value discrimination circuit 9 discriminates the value of the current 1^ or rll flowing through the detection resistor 6a or 6b, and the selected two wire electrodes are 4b-4d. It will be moved from 4cm 4e or 4a-4c.

Next, the current value discrimination circuit will be explained in detail with reference to FIG.

FIG. 4 is a circuit diagram showing a current value discrimination circuit of an embodiment of the coordinate detection device according to the present invention, in which 10a and 10b are comparators, and 24 is a NOR gate.

A value of the current flowing through the detection resistors 6a and 6b.

(2) Level judgment is performed by comparators IQa and 10b, respectively. That is, the contact point 8 is connected to the wire electrode 4b.
4d, one of the resistance values R, , R1 becomes small and the other becomes large. One of the current values 1a and Ia becomes larger and the other becomes smaller.

These currents I and I are compared and determined by the comparison lK10a and 10b. Here, the comparators 10a, 10
b is configured such that its discrimination level can be set by variable resistors 23a and 23b, respectively. and,
The outputs of these comparators 10a and lOb are connected to the NOR gate 2.
4, it is determined whether the contact point 8 is in the vicinity of the line electrode 4b or 4d, and if so, the current ■. .
4C-40 or 4a-40) is selected, whereby the coordinates of the contact point 8 will be detected accurately.

In the above, the current value discrimination circuit may discriminate using only the current of one of the detection resistors, the circuit configuration may be varied variously, and the function of the other switching means, etc. In addition, in the above embodiment, two line electrodes separated by one line electrode are sequentially selected and connected by a switch means. Of course, it is possible to sequentially select and connect two line electrodes separated by two line electrodes or three line electrodes separated.

〔Effect of the invention〕

As described in detail above, even when the contact point is near a line electrode, the coordinate detection device according to the present invention can detect the contact point by using two line electrodes separated by at least one line electrode other than the line electrode. Since the position of the contact point is detected, the coordinates can be detected with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing the main parts of an embodiment of the coordinate detection device according to the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG. An equivalent circuit diagram, FIG. 4 is a circuit diagram showing a current value discrimination circuit of an embodiment of the coordinate detection device according to the present invention, and FIG. 5 is a perspective view schematically showing the main parts of a conventional coordinate detection device. Figure 6 is a configuration diagram showing the main parts of another conventional coordinate detection device, Figure 7 is a circuit diagram showing the equivalent circuit of Figure 6, and Figure 8 is a measurement using the coordinate detection device shown in Figure 6. 3 is a graph showing the relationship between distance and current ratio. la, lb...first detection resistor, 2...first switch means, 3...first resistance plate, 3a to 3g...wire electrode, 4...second resistor Plate, 4a to 4h... Line electrode, 5... Second switch means, 6a, 6b... Second detection resistor, 7... Constant current power supply, 8... Contact point, 9 .9'...Current value discrimination circuit.

Claims (1)

[Claims] a first resistance plate having a plurality of parallel line electrodes formed on the resistance film; and a second resistance plate having a plurality of parallel line electrodes orthogonal to the plurality of line electrodes of the first resistance plate formed on the resistance film. 2 resistance plates,
a first switch means for sequentially selecting two line electrodes separated by at least one line electrode from the plurality of line electrodes of the first resistance plate; and at least one line electrode from the plurality of line electrodes of the second resistance plate. a second switch means for sequentially selecting two wire electrodes separated by one wire electrode; a power source; and a second switch means for detecting a current supplied from the power source and corresponding to a pressed position of the resistor plate; A coordinate detection device comprising current value determining means for determining whether a value is within a desired range.