JPH05241719A - Pressure-sensitive input device - Google Patents

Abstract

PURPOSE:To detect the accurate positions by preventing the disturbance of the potential distribution of a conductive film that is caused by the friction produced against a spacer. CONSTITUTION:A 1st sheet 20 produces the voltage drop in proportion to the distance between a conductive film 22 and an electrode, and a 2ns sheet 21 produces the voltage drop in proportion to the distance between a conductive film 23 and an electrode respectively. A 1st spacer 27 is formed on the film 22 of the sheet 20, and a 2ns spacer 28 is formed on the film 23 of the sheet 21. A 3rd sheet 24 is provided between both sheets 20 and 21 whose conductive film surfaces are opposite to each other with a space secured between them. Then the conductive films 25 and 26 formed on both sides of the sheet 24 are abutted on the spacers 27 and 28 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive input device, and more particularly to a pressure-sensitive input device for detecting a position using a pressure-sensitive system.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional pressure-sensitive input device usually has two sheets 10 each having a conductive film on one side.
11 is laminated so that the conductive film surfaces 12 and 13 face each other, and a spacer 14 is interposed between the conductive film surfaces 12 and 13 to maintain insulation between the conductive films. To detect the position, first, a voltage is applied to one conductive film 12 so that a voltage drop occurs in proportion to the distance from the electrode 12a, and the pen 15 presses the conductive film 12 at a position where the two conductive films 12 and 13 contact each other. The potential is read through the other conductive film 13, and the distance from the electrode is calculated by calculation. An equivalent circuit in this case is shown in FIG.
The resistance R ₁₂ represents the resistance value of the conductive film 12, the resistance R ₁₃ represents the resistance value of the conductive film 13, and 16 represents a voltmeter.
The internal resistance of the voltmeter 16 is sufficiently larger than the resistance R ₁₃ , and this resistance R ₁₃ can be ignored, and the resistance value from the electrode 12a of the resistance R ₁₂ to the contact point 17 is read by the voltmeter 16. Can be calculated from Next, a voltage is applied to the other conductive film 13 so that the voltage application direction is perpendicular to the previous direction,
Do the same. The position coordinates of the pen are detected as described above.

[0003]

The spacer 14 is formed on either one of the two conductive films 12 and 13. In this case, the conductive film 1 on which the spacer 14 is formed
The conductive film 12 on the side different from 3 deteriorates due to friction with the spacer 14 as the use progresses. When a voltage is applied to the deteriorated conductive film 12, there is a problem in that the potential distribution is disturbed and accurate position detection becomes impossible. On the other hand, on the side on which the spacer 14 is placed, the relative positional relationship with the spacer 14 does not always change, and there is no deterioration due to friction.

The present invention has been made in view of the above points,
An object of the present invention is to provide a pressure-sensitive input device capable of preventing the potential distribution of the conductive film from being disturbed by friction with the spacer and enabling accurate position detection.

[0005]

According to the pressure-sensitive input device of the present invention, a voltage is applied between electrodes on both ends in the X direction of a conductive film provided on one surface to generate a voltage proportional to a distance from one electrode. A voltage is applied between the first sheet that causes a drop and the electrodes on both sides of the conductive film provided on one surface in the Y direction that is orthogonal to the X direction to cause a voltage drop that is proportional to the distance from one electrode. A second sheet, an insulating first spacer formed on the conductive film of the first sheet, an insulating second spacer formed on the conductive film of the second sheet, and a conductive layer. The above-mentioned first and second films whose film surfaces are opposed to each other.
And a third sheet in which the conductive films provided on both surfaces are placed in contact with the first and second spacers, respectively.

[0006]

In the present invention, a spacer is formed on the conductive films of the first and second sheets which cause a voltage drop proportional to the distance from the electrode, and the conductive film of the third sheet is in contact with the spacer. Since the potentials are read, the conductive films of the first and second sheets do not deteriorate due to friction even when they are used, and the potential distributions of the conductive films of the first and second sheets are disturbed. This can be prevented and accurate position detection can be performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional structural view of an embodiment of the device of the present invention.

In the figure, each of the elastic sheets 20 and 21 has conductive films 22 and 23 on one surface, and the conductive films 22 and 23 are separated and opposed to each other. Between the sheets 20 and 21, there are conductive films 25 on both sides.
An elastic sheet 24 having spacers 27, 28
Sandwiched through. The sheet 24 is made of the conductive film 2
Conductive films 25 and 26 are respectively brought into contact with spacers 27 and 28 which are arranged in a mesh shape or a dot shape in 2, 23 and are formed in an insulating and paraboloidal shape.

The conductive film 22 applies a voltage between the electrodes 22a and 22b to cause a voltage drop proportional to the distance from the electrode 22a in the X direction, and the conductive film 23 is similarly moved in the Y direction orthogonal to the X direction. A voltage drop is caused and the sheet 20 is pressed by the pen 30 to deform the sheets 20 and 24, and the potential at the point where the conductive films 22 and 25 and 23 and 26 contact each other is read through the conductive films 25 and 26.

Here, in order to press the three sheets 20, 21, 24 in order to input with a pressing force equivalent to that of a conventional input device that presses two sheets, it is necessary to take measures.
Therefore, the conductive film 2 of the sheets 20 and 21 shown in FIG.
If the areas of the bottom surfaces of the spacers 27 and 28 provided in Nos. 2 and 23 are S ₂₇ and S ₂₈ , the heights are H ₂₇ and H ₂₈ , and the spacer intervals are L ₂₇ and L ₂₈ , the area S ₂₈ is S _It is made smaller than ₂₇ , the height H ₂₈ is made smaller than H ₂₇ , and the spacer interval L ₂₈ is made larger than L ₂₇ . Thereby, the conductive film 2
The pressing force required for contacting each of 2 and 25 and 23 and 26 is reduced.

FIG. 3 is a circuit diagram of the first embodiment of the device of the present invention. When measuring the X coordinate, switch SW
1, SW2 are connected to the A side, and a voltage V is applied between the electrodes 22a and 22b of the conductive film 22 by the DC voltage source 31.
The voltmeter 32 is connected between the electrode 22b of the conductive film 22 and the electrode 25a of the conductive film 25.

When the pen 30 presses the conductive films 22 and 25, the potential of the conductive film 22 at the pen pressing position is measured by the voltmeter 32 through the conductive film 25, and the X coordinate is detected based on this value.

When measuring the X coordinate, the switches SW1 and SW
Two of them are connected to the B side, and the conductive film 2 is connected by the DC voltage source 31.
The voltage V is applied between the electrodes 23a and 23b of
2 is an electrode 23b of the conductive film 23 and an electrode 26a of the conductive film 26.
Connect between and.

The conductive films 23 and 26 come into contact with each other when pressed by the pen 30, the potential at the pen pressed position of the conductive film 23 is measured by the voltmeter 32 through the conductive film 26, and the X coordinate is detected based on this value.

Here, as the use progresses, the spacer 2
The conductive films 25 and 26 on both sides of the sheet 24 are deteriorated by the friction with the sheet 28 and the sheet 28, respectively. However, this conductive film 25, 2
Since 6 is connected to the voltmeter 32 on the potential reading side, even if the resistance value changes a little due to the above deterioration, it is sufficiently smaller than the internal resistance of the voltmeter 32, and the resistance values of the conductive films 25 and 26 are small. Is ignored. Further, since the spacers 27 and 28 are formed on the conductive films 22 and 23 to which a voltage is applied between the electrodes on both ends, the conductive films 22 and 23 and the spacer 2 are formed.
The relative positional relationship with 7, 28 does not always change, and the conductive films 22, 23 are not deteriorated by friction and the potential distribution is not disturbed.

This allows the conductive film 2 to be used even if it is used.
It is possible to prevent the potential distributions of 2 and 23 from being disturbed and to perform accurate position detection.

By the way, as shown in FIG. 4, the switch SW2 can be eliminated by using a conductive sheet 33 which is entirely conductive instead of the sheet 24.

FIG. 5 shows a circuit configuration diagram of a second embodiment of the device of the present invention. In the figure, those parts which are the same as those corresponding parts in FIG. 3 are designated by the same reference numerals, and a description thereof will be omitted.

In FIG. 5, the DC power supplies 31 and 41 are respectively connected between the electrodes 22a and 22b of the conductive films 22 and 23 and 23.
a voltage V is applied between a and 23b, and voltmeters 32 and 42
The conductive films 22 and 25 are connected to each other, and the conductive films 23 and 26 are connected to each other.

In this case, since the X and Y coordinates can be measured simultaneously by the voltmeters 32 and 42 respectively, the measurement time interval of the X and Y coordinates can be halved as compared with the embodiment of FIG. Can be measured.

[0021]

As described above, according to the pressure-sensitive input device of the present invention, it is possible to prevent the potential distribution of the conductive film from being disturbed due to the friction with the spacer, and it is possible to accurately detect the position. Extremely useful.

[Brief description of drawings]

FIG. 1 is a cross-sectional structural view of a device of the present invention.

FIG. 2 is a diagram for explaining a spacer.

FIG. 3 is a circuit configuration diagram of the device of the present invention.

FIG. 4 is a circuit configuration diagram of the device of the present invention.

FIG. 5 is a circuit configuration diagram of the device of the present invention.

FIG. 6 is a cross-sectional structural view of a conventional device.

FIG. 7 is an equivalent circuit diagram of a conventional device.

[Explanation of symbols]

 20, 21, 24 Sheet 22, 23, 25, 26 Conductive film 27, 28 Spacer 30 Pen

Front page continuation (72) Inventor Katsuya Irie 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (4)

[Claims] 1. A first sheet (2) for applying a voltage between electrodes at both ends in the X direction of a conductive film (22) provided on one surface to cause a voltage drop proportional to a distance from one electrode.
0) and a conductive film (23) provided on one surface, a voltage is applied between the electrodes at both ends in the Y direction orthogonal to the X direction to generate a voltage drop proportional to the distance from one electrode. Sheet (21), an insulating first spacer (27) formed on the conductive film of the first sheet, and an insulating second spacer formed on the conductive film of the second sheet. (28) and the conductive film (2 provided on both surfaces of the first and second sheets sandwiching the conductive film surfaces so as to face each other.
5, 26) and a third sheet (24) in which the first and second spacers are brought into contact with each other, and the first or second sheet is pressed to remove the first and second sheets. A sense characterized by detecting the X-coordinate and the Y-coordinate of the pressed point by reading the potential of the contact point between the conductive film and the conductive films on both surfaces of the third sheet from the conductive film on both surfaces of the third sheet. Pressure input device. 2. The pressure-sensitive input device according to claim 1, wherein the height of the second spacer is smaller than the height of the first spacer, and the first sheet is pressed. Pressure sensitive input device. 3. The pressure-sensitive input device according to claim 1, wherein the area of the second spacer is smaller than the area of the first spacer, and the first sheet is pressed. Pressure input device. 4. The pressure-sensitive input device according to claim 1, wherein a spacing between the second spacers is larger than a spacing between the spacers of the first spacer, and the first sheet is pressed. Pressure sensitive input device.