JP2647275B2 - Coordinate input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device used for office automation equipment, personal equipment and the like.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed as a pointing point detection method in a coordinate input device, in addition to an electrostatic induction method, an electromagnetic induction method, and a pressure-sensitive method. However, only the above three types have been put to practical use. The electrostatic induction method is a method in which a pulse signal input to an electrode wire stretched around a tablet is detected by a detection pen having a high input impedance, and the position of the detection pen on the tablet is detected. In addition, the electromagnetic induction method has a structure in which a coil is wound around a ferrite core with a gap, and is generated in an electrode wire when a current-driven electromagnetic pen is brought close to an electrode wire stretched around a tablet. In this method, the position of the electromagnetic pen on the tablet is detected by detecting an induced current. Further, the pressure-sensitive method detects a resistance value of the sheet resistance sheet between a sheet electrode arranged around the sheet resistance sheet constituting the tablet and a location indicated by the pen, and detects a pen on the tablet. Is a method of detecting the position of

[0003]

However, each of the above-mentioned designated point detection systems based on the electrostatic induction system, the electromagnetic induction system, and the pressure-sensitive system has the following problems. In the case of the above-mentioned electrostatic induction system, a plurality of electrode wires must be stretched in parallel on the tablet. In order to detect the position of the sensing pen by the induced current generated in the sensing pen, a pulse train according to a predetermined rule must be sequentially input to the plurality of electrode wires. For this reason, there is a problem that the tablet drive circuit and the detection signal processing circuit become complicated and cost increases.

Also, in the case of the above-mentioned electromagnetic induction system, it is necessary to extend electrode wires on the tablet. At that time, in order to be able to detect the position of the electromagnetic pen by the induced current generated in the electrode wire, the direction of the electrode wire is arranged to be reversed at a predetermined interval, or the phase of the induced current is changed. Or 90 ° different. Further, a complicated processing circuit is required to process the detected induced current. Therefore, there is a problem that the cost increases as in the case of the electrostatic induction method.

Further, in the case of the above-mentioned pressure-sensitive method, the upper sheet resistance sheet is deformed by pressing two stacked sheet resistance sheets with the pen, and is brought into contact with the lower sheet resistance sheet. The resistance value of the sheet resistance sheet between the sheet electrode and the location indicated by the pen is detected. Therefore, it can be realized at low cost as compared with the electrostatic induction method and the electromagnetic induction method. However, since deformation of the sheet resistance sheet and contact between the sheet resistance sheets are repeated, there is a problem in durability. Further, as described later in detail, since a voltage drop occurs in the sheet electrode provided on the sheet resistance sheet, there is a problem that the linearity near the sheet electrode is reduced.

Hereinafter, the problem of the pressure-sensitive method will be described in more detail. FIG. 14 is a diagram illustrating an example of a conventional pressure-sensitive tablet. The pressure-sensitive tablet is formed by laminating two transparent sheet resistance sheets 1 provided with two sheet electrodes 2 facing each other such that the direction connecting the two sheet electrodes 2 is orthogonal. It is schematically configured. Here, FIG. 14 shows a state where two transparent sheet resistance sheets 1 are laminated. The sheet electrode 2 is formed by applying a silver paste on the sheet resistance sheet 1 in a strip shape. And
One end of each of the sheet electrodes 2, 2, ... is connected to one end of a lead wire 3, 3, ... formed by applying a silver paste on the corresponding sheet resistance sheet 1 in a string shape. The other end of each of the lead wires 3, 3,... Is gathered in a solder area 4 provided in one place of the pressure-sensitive tablet, and one end of the metal wire 5, 5,. Have been. Thus, the pressure-sensitive tablet is connected to the processing circuit via the metal wires 5, 5,... To constitute a coordinate input device.

In the pressure-sensitive tablet having the above-described structure, when the deformation of the sheet resistance sheet 1 and the contact of the double-sided resistance sheets 1 and 1 are repeated and the sheet resistance sheet 1 is deteriorated, the coordinates of the designated point designated by a pen or the like. Erroneous detection occurs when detecting. In such a case, the trouble can be solved by replacing only the pressure-sensitive tablet. However, as described above, since the pressure-sensitive tablet is soldered to the metal wires 5, 5,... For connection to the processing circuit, it is impossible to replace only the pressure-sensitive tablet. Therefore, the life of the pressure-sensitive tablet (more simply, the life of the sheet resistance sheet 1) does not recover and becomes the life of the coordinate input device.

The linearity of coordinate detection is affected by an equipotential distribution on the sheet resistance sheet 1 generated when a voltage is applied to the sheet electrodes 2 and 2. FIG. 15 shows an equivalent circuit of one sheet resistance sheet 1. The sheet resistance sheet 1 is regarded as having a large number of linear resistances of RΩ arranged in parallel, and each of the two sheet electrodes 2, 2 disposed in parallel to opposing sides of the sheet resistance sheet 1 is connected to the resistance of rΩ. Let it be a linear resistor. Here, when a high voltage is applied to one of the extraction electrodes provided on each of the sheet electrodes 2 and 2 and a low voltage is applied to the other, the equipotential lines on the sheet resistance sheet 1 are changed to both sheet electrodes. If it is parallel to 2, 2, the linearity of coordinate detection is good. However, strictly speaking, when a current flows through the sheet electrode 2, a slight voltage drop occurs. Therefore, when the value of the resistance “r” of the sheet electrode 2 is large, the voltage drop cannot be ignored, and FIGS.
8, sheet resistance sheet 1 near sheet electrode 2
The upper equipotential lines are distorted.

FIG. 16 shows an equipotential line when the lead terminals 6, 6 provided on the two sheet electrodes 2, 2 are provided at ends of the sheet electrodes 2, 2 which are not opposed to each other. Show. FIG. 17 shows equipotential lines in the case where the extraction terminals 6, 6 are provided at ends of the sheet electrodes 2, 2 facing each other. FIG. 18 shows the connection between the extraction terminals 6,6.
Indicates equipotential lines in the case where they are provided at the central portions of the sheet electrodes 2 and 2, respectively. Here, when the resistance value “r” of the sheet electrode 2 is the same, the degree of the voltage drop increases as the distance between the end of the sheet electrode 2 and the extraction terminal 6 increases. Therefore, in the case of FIG. 18, the degree of distortion of the equipotential lines is small.

An object of the present invention is to provide a low-cost coordinate input device capable of detecting coordinates with high linearity and having a long life.

[0011]

In order to achieve the above object, a coordinate input device according to a first aspect of the present invention includes two coordinate detection sheets each having sheet electrodes on opposite sides of a sheet resistance sheet. The sheet resistance sheets of the two coordinate detection sheets are stacked at predetermined points so that the directions connecting the sheet electrodes are orthogonal to each other and are pressed at any point on the surface of one coordinate detection sheet. A pressure-sensitive tablet configured to be electrically connected, a main body in which the pressure-sensitive tablet is stored, and the pressure-sensitive tablet placed on top of the pressure-sensitive tablet stored in the main body, and Attached to the tablet fixing part and the main body or the tablet fixing part,
One end is connected to a lead wire, and the other end is a terminal that is pressed against and electrically connected to a sheet electrode of the coordinate detection sheet when the pressure-sensitive tablet is fixed by the tablet fixing portion; And a coordinate detection unit that detects the potential difference between the electrode of the coordinate detection sheet and the pressed point and detects the coordinates of the pressed point, and inputs the coordinates of the pressed point on the pressure-sensitive tablet. It is characterized by doing.

According to a second aspect of the present invention, in the coordinate input device, two coordinate detection sheets having sheet electrodes on opposite sides of the sheet resistance sheet are connected at right angles to each other. The sheet resistance sheets of the two coordinate detection sheets are electrically connected to each other at a pressed point by pressing an arbitrary portion on the surface of one coordinate detection sheet while being stacked at a predetermined interval. A pressure-sensitive tablet having one end connected to any one of the sheet electrodes and the other end converged at one location on the coordinate detection sheet; and a main body in which the pressure-sensitive tablet is housed. And a tablet fixing portion mounted on the upper part of the pressure-sensitive tablet housed in the main body and fixing the pressure-sensitive tablet to the main body, and converged at one place of the pressure-sensitive tablet. A coordinate detecting unit that is detachably connected to the other end of the lead wire via a connector, detects a potential difference between a sheet electrode and a pressed point on the coordinate detection sheet, and detects the coordinates of the pressed point. And inputting the coordinates of the pressed point on the pressure-sensitive tablet.

The coordinate input device according to a third aspect of the present invention is the coordinate input device according to the first aspect.
In the coordinate input device according to the invention, the shape of the terminal is configured to be connected to the sheet electrode over the entire length of the sheet electrode provided on the sheet resistance sheet, and a voltage is applied to each of the sheet electrodes. In this case, no distortion occurs in the equipotential lines between the two sheet electrodes on the sheet resistance sheet.

A coordinate input device according to a fourth aspect of the present invention comprises
In the coordinate input device of the invention or the second invention, each of the two sheet electrodes provided on the opposite sides of the sheet resistance sheet has the shape of the side facing the other sheet electrode as the terminal or the lead wire. Between the two sheet electrodes on the sheet resistance sheet when a voltage is applied to each of the sheet electrodes, so as to approach the other sheet electrode by a distance corresponding to a voltage drop due to a distance from a connection point with the sheet electrode. Is characterized in that no distortion is caused in the equipotential lines in.

The coordinate input device according to a fifth aspect of the present invention is the coordinate input device according to the first aspect.
In the coordinate input device according to any one of the first to fourth inventions, the main body has a display portion for displaying input characters and figures on a screen at an upper portion, and the coordinate detection sheet constituting the pressure-sensitive tablet is transparent. The tablet fixing section is characterized in that the pressure-sensitive tablet stacked on the screen of the display section and housed in the main body is fixed.

[0016]

According to the first aspect of the invention, the pressure-sensitive tablet is stored in the main body, and the tablet fixing portion is mounted on the upper part of the stored pressure-sensitive tablet. Thus, the pressure-sensitive tablet is fixed to the main body by the tablet fixing portion. At that time, one end of the terminal attached to the main body or the tablet fixing portion is pressed against the sheet electrode of the coordinate detection sheet constituting the pressure-sensitive tablet,
The sheet electrode and the terminal are electrically connected. Since the other end of the terminal is connected to the coordinate detecting unit via a lead wire, the pressure-sensitive tablet is connected to the coordinate detecting unit. In this state, an arbitrary position on the surface of one coordinate detection sheet of the two coordinate detection sheets constituting the pressure-sensitive tablet which is stacked at a predetermined interval so that the directions connecting the sheet electrodes are orthogonal to each other. Is pressed, the two double-sided resistance sheets are electrically connected at the pressing point. Then, the potential difference between the sheet electrode of the coordinate detection sheet and the pressed point is detected by the coordinate detection unit, and the coordinates of the pressed point are detected.

In this way, it is assumed that when the coordinates of the pressed point on the pressure-sensitive tablet are detected and input, the coordinate detection sheet is degraded and the coordinates of the pressed point cannot be correctly detected. In that case, the tablet fixing part is removed from the main body. Then, one end of the terminal attached to the tablet fixing portion is separated from the sheet electrode of the coordinate detection sheet, and the pressure-sensitive tablet is in a free state with respect to the main body. In this way, only the pressure-sensitive tablet is removed from the main body and replaced, and the coordinate input device can detect the pressed point again.

Further, in the second invention, the coordinates of the pressed point are erroneously detected when the coordinates of the pressed point on the pressure-sensitive tablet are inputted in the same manner as in the first invention. Let's say that. In that case, the tablet fixing part is removed from the main body. Then, a connector for detachably connecting the coordinate detection unit and the lead wire of the pressure-sensitive tablet is separated. Then, the pressure-sensitive tablet becomes free with respect to the main body. Thus, only the pressure-sensitive tablet is removed from the main body and replaced, and the coordinate input device can detect the pressed point again.

According to the third aspect of the present invention, a voltage is applied to each of the sheet electrodes via the terminals formed so as to be connected to the sheet electrodes over the entire length of the sheet electrodes provided on the coordinate detection sheet. Applied. Therefore, no distortion occurs in the equipotential lines between the two sheet electrodes on the sheet resistance sheet. Thus, the coordinates of the pressed point are accurately detected by the coordinate detection unit based on the equipotential lines without distortion on the sheet resistance sheet, and the highly linear coordinates of the pressed point are detected. You.

Further, in the fourth invention, the shape of the side facing the other sheet electrode is made closer to the other electrode side by a distance corresponding to a voltage drop due to a distance from a connection point with the terminal or the lead wire. A voltage is applied to the sheet electrode thus formed. Then, no distortion occurs in the equipotential lines between the two sheet electrodes on the sheet resistance sheet. Thus, based on the equipotential lines on the sheet resistance sheet that do not cause distortion,
The coordinates of the pressed point are accurately detected, and the coordinates with high linearity related to the pressed point are known.

Further, in the fifth invention, a pressure-sensitive tablet formed of a transparent coordinate detection sheet is stacked on a screen of the display unit and stored in the main body, and the tablet fixing unit is placed and fixed. . Then, by pressing an arbitrary point on the surface of the coordinate detection sheet corresponding to the input point on the screen seen through the transparent pressure-sensitive tablet, the input point on the screen is more accurately and easily indicated. Then, the two sheet resistance sheets are electrically connected at the pressing point, and the coordinate detecting unit detects a potential difference between the sheet electrode of the coordinate detecting sheet and the pressing point, and displays an instruction on the screen. The coordinates of the point are detected. Thus, when the coordinates detection sheet is deteriorated while the coordinates of the input point on the screen are being input, the tablet fixing portion is removed from the main body, and only the pressure-sensitive tablet is removed from the main body. Replaced easily.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. <First Example> FIG. 1 is a configuration diagram of a coordinate input device according to the present embodiment. The coordinate input device includes a main body 11 having a built-in display unit 15 such as a liquid crystal display or an electroluminescence display, and a display unit 15 stacked on the display unit 15 and indicated by a pen (not shown) or the like. A pressure-sensitive tablet (hereinafter, simply referred to as a tablet) 12 for detecting the coordinates of the designated point above, and a fixing plate 13 for fixing the position of the tablet 12 to the display unit 15 so as not to be shifted. You. Here, one side of the fixing plate 13 is rotatably attached to one side of the main body 11 by a hinge, and can be easily opened and closed.

As will be described in detail later, the tablet 12 has a first coordinate detection sheet 21 for detecting, for example, an x coordinate.
And y are stacked orthogonally on the first coordinate detection sheet 21 and y
And a second coordinate detection sheet 22 for detecting coordinates. When the tablet 12 is stacked on the display unit 15 in the vicinity of each of the two sides of the window 14 in the main body 11 that look into the display unit 15 in the y direction,
Sheet electrodes 25 and 26 provided on the coordinate detection sheet 22
There are provided metal mounting terminals 19 and 20 for electrically connecting the processing circuit installed in the main body 11 to the second coordinate detection sheet 22 by pressing against the second coordinate detection sheet 22. On the other hand, the fixed plate 1
In the vicinity of each of two sides facing the x direction of the window 18 looking through the display unit 15 in the display unit 3, the tablet 12 is placed on the display unit 1.
5, when pressed on the sheet electrodes 23 and 24 provided on the first coordinate detection sheet 21,
Mounting terminals 16 and 17 for electrically connecting the coordinate detection sheet 21 are provided.

The tablet 12 is configured as follows. That is, as shown in FIG. 2, a transparent resistance film such as indium tin oxide (hereinafter, referred to as ITO) is applied on a transparent substrate such as polyethylene or glass to form a rectangular sheet resistance sheet. Then, sheet electrodes 23 and 24 formed by applying a silver paste or the like along the sides 21 ′ and 21 ″ are arranged on the resistive film on the sides 21 ′ and 21 ″ facing the longitudinal direction of the sheet resistance sheet. Set up. Thus, the transparent first coordinate detection sheet 21 is formed. Sheet electrodes 25 and 26 are disposed on sides 22 ′ and 22 ″ of the rectangular sheet resistance sheet formed in the same manner in the longitudinal direction to form the transparent second coordinate detection sheet 22. The first coordinate detection sheet 21 and the second coordinate detection sheet 22 are laminated such that their longitudinal directions are orthogonal to each other and the resistive films are opposed to each other. A space is provided by a dot spacer or the like between the two-coordinate detection sheet 22. Thus, when the surface of the second coordinate detection sheet 22 located on the upper side is pressed by a pen or the like, both coordinates are detected only at the pressed point. Seat 21,
The resistance films 22 are brought into contact with each other to make them electrically conductive.

As described above, when the first coordinate detection sheet 21 and the second coordinate detection sheet 22 are stacked, the area where the two coordinate detection sheets 21 and 22 overlap is the area of the screen in the display unit 15. So that Then, each of the sheet electrodes 23, 24, 25, and 26 is prevented from covering the area. In this case, since the two coordinate detection sheets 21 and 22 are laminated with the resistance films facing each other, the sheet electrodes 23 and 24 disposed on the resistance film of the first coordinate detection sheet 21 face upward, while The sheet electrode 25 disposed on the resistive film of the second coordinate detection sheet 22,
26 faces downward. As described above, the tablet 12 configured by stacking the first coordinate detection sheet 21 and the second coordinate detection sheet 22 is housed by being fitted into the window 14 of the main body 11 and closing the fixing plate 13. A coordinate input device is configured.

At this time, the extraction terminals 16, 17, 19,
Reference numeral 20 denotes a contact surface provided on the other end when the mounting surface provided on one end is mounted on the main body 11 or the fixing plate 13.
6 ', 17', 19 ', and 20' are made of a resilient metal so as to be floated from the surface to be mounted. By doing so, when the tablet 12 is stored in the main body 11 and the fixing plate 13 is closed, the contact surfaces 16 ′, 1
7 ', 19', 20 'correspond to the sheet electrodes 23,24,25,
26, the tablet 12 and the processing circuit are electrically and reliably connected. At the same time, tablet 12
Is securely fixed to a predetermined position of the main body 11.

When the fixing plate 13 is opened, the contact surfaces 16 ', 17' of the extraction terminals 16, 17 are separated from the sheet electrodes 23, 24. Therefore, the tablet 12 can be made free with respect to the main body 11, and the tablet 12 can be easily taken out from the main body 11. Therefore, when the second coordinate detection sheet 22 deteriorates due to repetition of deformation due to pen pressing, and an obstacle such as erroneous detection such as chattering and bending or an input failure occurs, as described above, the fixing plate 13 is used. Is opened, the tablet 12 is taken out of the main body 11, and can be easily replaced with a new tablet 12. Thus, the coordinate detection sheet 21,
Since only the tablet 12 needs to be replaced when 22 deteriorates, there is no need to replace the entire coordinate input device, and the life of the coordinate input device is extended.

That is, the tablet fixing section is constituted by the fixing plate 13, and the coordinate detecting section is constituted by the processing circuit.

The coordinate input device constructed as described above has an appearance as shown in FIG. The coordinate input device operates and operates as follows to specify and input coordinates on the display unit 15. That is, while viewing the screen of the display unit 15 through the transparent tablet 12 from the window 18 of the fixed plate 13 and the window 14 of the main body 11, the input point on the screen is pressed with the pen 31. To instruct. Then, the second coordinate detection sheet 22 is deformed and is electrically connected to the first coordinate detection sheet 21 at the designated point. As a result, the first coordinate detection sheet 21 and the second coordinate detection sheet 22, which have formed two resistors different from each other before the conduction, are obtained by further connecting the two resistors in parallel to the designated point. To form four resistors connected in series.

Therefore, the first coordinate detection sheet 21
When a potential difference is applied between the two sheet electrodes 23 and 24 of the second coordinate detection sheet 22 and the two sheet electrodes 25 and 26 of the second coordinate detection sheet 22 are set to high impedance, for example, Become. This potential is a potential obtained by dividing the potential difference between the two sheet electrodes 23, 24 by the ratio of the distance from each sheet electrode 23, 24 to the designated point. Therefore, the x-coordinate of the designated point can be detected by the processing circuit by detecting the value of the potential. Similarly, a potential difference is applied between the two sheet electrodes 25 and 26 of the second coordinate detection sheet 22 while the two sheet electrodes 23 and 24 of the first coordinate detection sheet 21 are applied.
Is set to a high impedance, and for example, by detecting the value of the potential of the sheet electrode 23, the processing circuit can detect the y coordinate of the designated point.

As described above, in this embodiment, the main body 11 on which the fixing plate 13 is attached so as to be openable and closable by the hinge, and the tablet laminated on the display unit 15 of the main body 11 and fixed by the fixing plate 13 12, the coordinate input device is schematically configured. In the vicinity of each of the two opposing sides of the window 14 of the main body 11, an extraction terminal 1 formed of an elastic metal is provided.
9 and 20 are provided. On the other hand, in the vicinity of each of two opposing sides of the window 18 of the fixing plate 13, similar extraction terminals 16 and 17 are provided. As a result, the fixed plate 13
Is closed, the electrical connection between the extraction terminals 1617, 19, 20 and the corresponding sheet electrodes 23, 24, 25, 26 can be ensured, and the tablet 12 is connected to the main body 11
It can be securely fixed in the upper predetermined position. On the other hand, when the fixing plate 13 is opened, the tablet 12 can be set in a free state with respect to the main body 11. Therefore, when the coordinate detection sheets 21 and 22 deteriorate, only the tablet 12 can be easily replaced, and the life of the coordinate input device can be extended.

In the above embodiment, a space is provided between the first coordinate detection sheet 21 and the second coordinate detection sheet 22 by a dot spacer or the like. However, the present invention is not limited to this, and a resin sheet that conducts only in the pressure receiving direction by pressure may be interposed between the two coordinate detection sheets 21 and 22. Although the fixed plate 13 in the above embodiment is rotatable by a hinge, it may be opened and closed by sliding.
Further, it may be detachable from the main body 11. The point is that the tablet 12 can be fixed when the fixing plate 13 is placed on the main body 11, and at the same time, the extraction terminals 16, 17, 19, and 20 can reliably contact the corresponding sheet electrodes 23, 24, 25, and 26. It is good.

In the above embodiment, the extraction terminal 1
6, 17, 19 and 20 are formed by elastic metal plates. However, the extraction terminal of the present invention is not limited to this. For example, as shown in FIG.
An extraction terminal 32 made of a conductor (elastic / conductor) such as metal foil or conductive rubber may be attached to the main body 11 (or the fixing plate 13) side. Further, as shown in FIG. 5A, the extraction terminal 33 made of a bar-shaped metal is made to protrude from the main body 11 (or the fixing plate 13) by the urging force of the spring. And
As shown in FIG. 5B, when the tablet 12 is stored in the main body 11, the take-out terminal 33 may be pressed against the sheet electrode on the pressure-sensitive tablet 12 side by the urging force of the spring 34.

As described above, the sheet electrodes 23 and 24 of the first coordinate detecting sheet 21 located on the lower side of the tablet 12 face upward, while the sheet electrodes 25 and 24 of the second coordinate detecting sheet 22 located on the upper side. 26 faces downward. Therefore, as in each of the above-described embodiments, an extraction terminal that contacts the sheet electrodes 23 and 24 of the first coordinate detection sheet 21 (hereinafter, referred to as a first extraction terminal) is provided on the fixed plate 13 side,
An extraction terminal (hereinafter, referred to as a second extraction terminal) that contacts the sheet electrodes 25 and 26 of the second coordinate detection sheet 22 needs to be provided on the main body 11 side. As a result, it becomes necessary to electrically connect the processing circuit provided on the main body 11 side and the first extraction terminal provided on the fixing plate 13 side, and wiring and the like become complicated. Therefore, it is desirable that the first extraction terminal is also provided on the main body 11 side.

However, if the first extraction terminal is provided on the main body 11 simply in the same manner as the second extraction terminal, the first extraction terminal is located in the window 14 so that the tablet 12 is inserted into the main body 11.
It gets in the way when storing. Therefore, in this embodiment, as shown in FIG.
Are formed in a frame 35 (only one is shown) corresponding to the positions of the sheet electrodes 23 and 24 of the first coordinate detection sheet 21 when the tablet 12 is stored in the main body 11.
A lever 36 that slides in a direction toward the window 14 is provided. Then, an inverted J-shaped first extraction terminal 37 having elasticity is provided on the lower surface of the lever 36, and by sliding in the direction of the arrow (A) or the arrow (B), the curved distal end of the first extraction terminal 37 is provided. The part appears and disappears in the window 14. By doing so, as shown in FIG. 6A, the lever 36 is slid in the direction of the arrow (B) so that the first extraction terminal 37 is immersed in the frame 35, and
2 can be stored in the main body 11 without being obstructed by the first extraction terminal 37. After that, as shown in FIG. 6B, the lever 36 is slid in the direction of the arrow (A) to move the first extraction terminal 3
7 can be made to protrude into the window 14 and be pressed against the sheet electrode 23 (or the sheet electrode 24) of the first coordinate detection sheet 22 of the tablet 12.

FIG. 7 shows another embodiment having the same effect as the embodiment shown in FIG. Also in this case, the window 1 of the main body 11
4, a frame 41 corresponding to the position of the sheet electrodes 23 and 24 of the first coordinate detection sheet 21 when the tablet 12 is stored in the main body 11 (only one is shown).
Then, a columnar member 42 constituting a part of the window frame is attached so as to be rotatable around an axis. Then, an elastic plate-shaped first extraction terminal 43 protruding toward the window 14 is attached to one side surface 44 of the columnar member 42 facing the window 14. Thus,
By rotating the columnar member 42 back and forth about the axis, the first extraction terminal 43 can be protruded and retracted in the window 14.

FIG. 8 is an embodiment different from the embodiment shown in FIGS. Auxiliary terminals 45 and 47 are provided along two opposing sides different from the sides on which the sheet electrodes 25 and 26 are provided on the resistance film side of the second coordinate detection sheet 22. The auxiliary terminals 45 and 47
When the coordinate detection sheet 22 is stacked on the first coordinate detection sheet 21, the sheet electrodes 23 on the first coordinate detection sheet 21 side,
24 over the entire length. The auxiliary terminals 45 and 47 are respectively provided with extraction portions 46 and 48 extending outward. Here, the auxiliary terminals 45 and 47 are insulated from the resistance film on the second coordinate detection sheet 22. When the first extraction terminal is provided on the main body 11 and the fixing plate 13 is closed to fix the tablet 12 to the main body 11,
The extraction terminals are electrically connected to the extraction portions 46 and 48 of the auxiliary terminals 45 and 47 from below. Thus, the second
By providing the auxiliary terminals 45 and 47 on the coordinate detection sheet 22 side, the first extraction terminal can be provided on the main body 11.

FIG. 9 shows a tablet 12 in a further different embodiment. However, FIG. 9 shows a state where the sheet electrodes 23, 24, 25, 26 of the two coordinate detection sheets 21, 22 are visible through the transparent coordinate detection sheets 21, 22. In this embodiment, the first
One ends of lead wires 51, 52 provided with silver paste or the like are connected to the sheet electrodes 23, 24 of the coordinate detection sheet 21. Further, the sheet electrode 2 of the second coordinate detection sheet 22
One ends of similar lead wires 53, 54 are connected to 5, 26, respectively.
Then, the other end of each of the lead wires 51, 52, 53, 54 converges to one location of the tablet 12. Then, the other end of the lead wire converged at one location and the metal wires 55, 55,... To the processing circuit are detachably connected by a press-connecting connector 56. By doing so, when the coordinate detection sheet of the tablet 12 is deteriorated, the fixing plate 13 is opened and the press-connecting connector 56 is detached.
Only the tablet 12 can be easily replaced.

<Second Example> In each of the above embodiments, it is inevitable that the equipotential lines are distorted due to the voltage drop of the sheet electrodes 23, 24, 25, and 26 themselves. Therefore, in the present embodiment, as shown in FIG.
The first extraction terminals 61 and 62 that come into contact with the sheet electrodes 23 and 24 of the coordinate detection sheet 21 (actually, they are provided on the fixed plate 13 or the main body 11 as described above. The sheet electrodes 23 and 24 are formed with the same length as the sheet electrodes 23 and 24 using a material having a lower resistance than the sheet electrodes 23 and 24 such as a metal foil. Thus, the sheet electrodes 23 and 24 and the extraction terminals 61 and 62 are in contact with each other over the entire length. By doing so, even if the resistance values of the sheet electrodes 23 and 24 are somewhat large, the sheet electrodes 2
No voltage drop occurs at 3,24. Therefore, as shown in FIG.
4 and no distortion occurs. That is,
According to this embodiment, it is possible to detect coordinates with high linearity.

The same effect as in the above embodiment can also be obtained by providing a plurality of extraction terminals corresponding to one sheet electrode and bringing the plurality of extraction terminals into contact with the entire one sheet electrode at equal intervals. Thus, an equipotential line without distortion can be obtained on the coordinate detection sheet. This is because, by increasing the number of the extraction terminals and shortening the distance between the extraction terminals, the voltage drop of the sheet electrode between the extraction terminals can be ignored.

As another method for obtaining an equipotential line without distortion on the coordinate detection sheet, FIGS.
As shown in (1), there is a method of changing the shape and arrangement of the sheet electrodes in accordance with the positional relationship between the extraction terminals that come into contact with each of the two paired sheet electrodes on the coordinate detection sheet. FIG. 11 shows an example in which the extraction terminals 65 and 66 are located at the center of the corresponding sheet electrodes 63 and 64,
FIG. 12 shows an example in which the extraction terminals 69 and 70 are located at opposite ends of the sheet electrodes 67 and 68, and FIG. 13 shows an example in which the extraction ends 73 and 74 are opposite ends of the sheet electrodes 71 and 72. It is an example in the case of being located in. As described above, the voltage drop of the sheet electrode increases as the distance from the extraction terminal increases. Therefore, as in the examples shown in FIGS. 11 to 13, by displacing the side facing the other sheet electrode at a position distant from the extraction terminal in the sheet electrode inward according to the degree of the voltage drop, there is no distortion. A potential line can be obtained.

[0042]

As is apparent from the above description, the coordinate input device of the first invention accommodates a pressure-sensitive tablet formed by laminating two coordinate detection sheets each having a sheet electrode in a main body and a tablet fixing section. So that the terminal attached to the main body or the tablet fixing portion is pressed against the sheet electrode to electrically connect the pressure-sensitive tablet and the coordinate detecting portion. Therefore, the pressure-sensitive tablet can be set in a free state with respect to the main body only by removing the tablet fixing portion. Therefore, if the pressure-sensitive tablet erroneously detects the coordinates of the designated point, only the low-cost pressure-sensitive tablet having a simple structure can be easily removed and replaced. That is, according to the present invention, a low-cost coordinate input device having a long life can be realized.

In the coordinate input device according to a second aspect of the present invention, the other end of the lead wire, one end of which is connected to the sheet electrode of the pressure-sensitive tablet, is detachably connected to the coordinate detecting unit via a connector. Therefore, the pressure-sensitive tablet can be set in a free state with respect to the main body by removing the tablet fixing portion and disconnecting the connector. Therefore,
According to the present invention, it is possible to easily remove and replace only a low-cost pressure-sensitive tablet having a simple structure and to realize a low-cost coordinate input device having a long life.

The coordinate input device according to a third aspect of the present invention is configured such that the terminal according to the first aspect is connected to the sheet electrode of the sheet resistance sheet constituting the coordinate detection sheet over the entire length of the sheet electrode. Therefore, no distortion occurs in the equipotential lines between the two sheet electrodes on the sheet resistance sheet. Therefore, according to the present invention, the coordinates of the pressed point on the coordinate detection sheet can be accurately detected by the coordinate detection unit, and the coordinates with high linearity at the pressed point can be detected.

Further, in the coordinate input device according to a fourth aspect of the present invention, each of the two sheet electrodes on the sheet resistance sheet is provided such that the side facing the other sheet electrode is connected to the terminal or the lead wire from the connection point. Since the shape is such that it approaches the other sheet electrode by a distance corresponding to the voltage drop due to the distance, no distortion occurs in the equipotential lines between the two sheet electrodes on the sheet resistance sheet. Therefore, according to the present invention, the coordinates of the pressed point on the coordinate detection sheet can be accurately detected by the coordinate detection unit, and the coordinates with high linearity at the pressed point can be detected.

According to a fifth aspect of the present invention, in the coordinate input device, a display section is provided on an upper portion of the main body, the pressure-sensitive tablet is formed transparent, and the transparent pressure-sensitive tablet is displayed on a screen of the display section. And the tablet is fixed to the main body by the tablet fixing portion, so that the coordinates on the screen viewed through the pressure-sensitive tablet can be indicated by pressing the pressure-sensitive tablet. Therefore, in addition to the effects of the above inventions, the coordinates on the screen can be more accurately and easily designated and input.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of a coordinate input device according to the present invention.

FIG. 2 is a configuration diagram of a pressure-sensitive tablet in FIG.

FIG. 3 is an external view of the coordinate input device of FIG. 1;

FIG. 4 is a diagram showing an extraction terminal different from the extraction terminal in FIG. 1;

FIG. 5 is an explanatory diagram of an operation of an extraction terminal different from the extraction terminal in FIGS. 1 and 4;

FIG. 6 is an explanatory diagram of an operation of an extraction terminal different from the extraction terminal in FIGS. 1, 4, and 5;

FIG. 7 is a view showing an extraction terminal different from the extraction terminals in FIGS. 1, 4, 5, and 6;

8 is an explanatory diagram of an extraction terminal different from the extraction terminals in FIGS. 1, 4, 5, 6, and 7. FIG.

FIG. 9 is an explanatory diagram when each sheet electrode in FIG. 1 is connected to a processing circuit via a lead wire.

FIG. 10 is a view showing an extraction terminal for obtaining an equipotential line without distortion.

FIG. 11 is a diagram showing a sheet electrode for obtaining an equipotential line without distortion.

FIG. 12 is a diagram showing a sheet electrode different from the sheet electrode in FIG. 11 for obtaining equipotential lines without distortion.

FIG. 13 is a view showing a sheet electrode different from the sheet electrodes in FIGS. 11 and 12 for obtaining equipotential lines without distortion.

FIG. 14 is a diagram showing a connection method with a processing circuit in a conventional pressure-sensitive tablet.

FIG. 15 is a diagram showing an equivalent circuit of a sheet resistance sheet.

FIG. 16 is a diagram illustrating a relationship between the position of a takeout terminal and an equipotential line.

FIG. 17 is a diagram showing a relationship between the positions of the extraction terminals and the equipotential lines different from FIG. 16;

FIG. 18 is a diagram illustrating a relationship between the position of an extraction terminal different from those in FIGS. 16 and 17 and an equipotential line.

[Explanation of symbols]

11 ... body, 12 ... pressure-sensitive tablet, 13 ... fixing plate, 14, 18 ...
Window, 15 ... display part, 16, 17, 19, 20, 32, 33, 37, 43, 45, 47
... Extraction terminals, 21 ... First coordinate detection sheet, 22 ... Second coordinate detection sheet, 23,24,25,26,63,64,67,68,71,72
... sheet electrodes, 36 ... levers, 42 ... columnar members, 56 ... press-fit connectors.

Claims (5)

(57) [Claims] 1. A sheet resistance sheet comprising two coordinate detection sheets having sheet electrodes on opposite sides thereof at predetermined intervals such that the directions connecting the respective sheet electrodes are orthogonal to each other. The pressure-sensitive tablet, which is configured so that the sheet resistance sheets of the two coordinate detection sheets are electrically connected to each other at a pressing point by pressing an arbitrary portion of the surface of the coordinate detection sheet, and the pressure-sensitive tablet is housed. A main body to be mounted, a tablet fixing portion mounted on the upper part of the pressure-sensitive tablet housed in the main body and fixing the pressure-sensitive tablet to the main body, and attached to the main body or the tablet fixing portion, One end is connected to a lead wire, and the other end is a sheet electrode of the coordinate detection sheet when the pressure-sensitive tablet is fixed by the tablet fixing portion. A terminal which is electrically connected to the lead wire by pressure contact with a terminal, and which detects a potential difference between an electrode of the coordinate detection sheet and a pressing point to detect the coordinates of the pressing point. A coordinate input device comprising: a unit for inputting coordinates of a pressed point on the pressure-sensitive tablet. 2. A sheet resistance sheet comprising two coordinate detection sheets having sheet electrodes on opposite sides thereof at predetermined intervals such that the directions connecting the respective sheet electrodes are orthogonal to each other. The sheet resistance sheet of the two coordinate detection sheets is configured to be electrically connected to each other at a pressed point by pressing an arbitrary portion on the surface of the coordinate detection sheet, and one end of the sheet resistance electrode is set to one of the sheet electrodes. A pressure-sensitive tablet disposed on the coordinate detection sheet, a main body in which the pressure-sensitive tablet is housed, and a lead-in wire that is stored in the main body. A tablet fixing portion mounted on the top of the pressure-sensitive tablet and fixing the pressure-sensitive tablet to the main body, and a connector at the other end of the lead wire converged at one place of the pressure-sensitive tablet And a coordinate detection unit that is detachably connected via the sensor and detects the potential difference between the sheet electrode and the pressed point on the coordinate detection sheet to detect the coordinates of the pressed point. A coordinate input device for inputting the coordinates of the pressed point in. 3. The coordinate input device according to claim 1, wherein the shape of the terminal is such that the terminal is connected to the sheet electrode over the entire length of the sheet electrode provided on the sheet resistance sheet. A coordinate input device wherein no distortion occurs in equipotential lines between two sheet electrodes on a sheet resistance sheet when a voltage is applied to each sheet electrode. 4. The coordinate input device according to claim 1, wherein each of the two sheet electrodes provided on opposing sides of the sheet resistance sheet is a side of the side facing the other sheet electrode. A sheet resistance sheet when a voltage is applied to each of the sheet electrodes, with a shape approaching the other sheet electrode by a distance corresponding to a voltage drop due to a distance from a connection point with the terminal or the lead wire. A coordinate input device wherein equidistant lines between the two upper sheet electrodes are prevented from being distorted. 5. The coordinate input device according to claim 1, wherein the main body has a display unit for displaying input characters and graphics on a screen at an upper portion, and the pressure-sensitive tablet. Wherein the coordinate detection sheet is transparent, and the tablet fixing unit is configured to fix the pressure-sensitive tablet stored in the main body stacked on a screen of the display unit. Coordinate input device.