JPH04312720A - Transparent flat-switch - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a transparent flat-switch so as to stably operate it by dispersing and fixing insulating grains of microscopic shape in one of mutually facing electrode-sheets, and forming a transparent resistance-film on the other thereof in such a condition that the thickness of the film may be unequal and an electrode may be partly exposed from the film. CONSTITUTION:Insulating micro-dot spacers 31 of microscopic shape are dispersed and fixed or a fixed electrode-sheet 32. A transparent resistance-film 25 is formed also on a movable electrode-sheet 26 in such a condition that the thickness of the film may be unequal and an electrode may be partly exposed from the film. When in regard to the above description the film 25 contacting each of the spacers 31 is formed in a thickness of not more than 1 micrometer, an excellent insulating condition can be kept in such a condition that the film is not pressed by a writing instrument P. When the film on the other hand has been pressed by the writing instrument, it causes its tunnel effect, its Schottky effect and its coherer effect so as to realize its accurately electrified condition, and also an electrode 22 can therefore be sufficiently protected by the film 25. This can improve the wear resistance of a transparent flat- switch to obtain the switch of reliable and stable operation, and of large area at low cost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent flat switch whose contacts are opened and closed by pressing a sheet with a pen touch.

0002

[Prior Art] Conventionally, this type of transparent flat switch has been manufactured, for example, in "Essentials of Input Device Development, Design, and Application" published by Japan Industrial Technology Center (November 30, 1985).
P. There is one described in 170.

FIGS. 6 to 10 are diagrams showing the configuration of the above-mentioned transparent flat switch. In each figure, 1 indicates a transparent first switch.
It is an insulating sheet with flexibility and is easily displaced in the thickness direction by applied pressure. A movable electrode 2 is provided on one side (back side) of the first insulating sheet, and is made of a transparent conductive film. 3 is a first movable lead that is one signal extraction electrode of the movable electrode 2; 4 is a second movable lead that is the other signal extraction electrode of the movable electrode 2; 5 is the first insulating sheet 1; the movable electrode 2 and the first and second movable leads 3, 4
The entire movable electrode sheet is shown.

6 is a transparent second insulating sheet corresponding to the first insulating sheet 1, and 7 is a fixed electrode provided on one side (front surface) of the second insulating sheet, which is formed of a transparent conductive film. There is. 8 is a first signal extraction electrode of one of the fixed electrodes 7;
9 is the second fixed lead which is the other signal extraction electrode of the fixed electrode 7; 10 is the entire fixed electrode sheet composed of the second insulating sheet 6, the fixed electrode 7 and the fixed leads 8 and 9; show. Further, 11 is an insulating dot spacer, which is made of an insulating material such as silicone, acrylic, epoxy, polyester, or urethane resin, and each has a diameter of 150 to 500 μm and a height of about 10% of the diameter. They are provided scattered on the fixed electrode 7 using screen printing.

Next, the operation will be explained. By pressing the transparent flat switch configured as shown in FIGS. 6 to 8 from above using a finger or a writing instrument P such as a ballpoint pen, as shown in FIGS. 9 and 10,
The flexible first insulating sheet 1 is displaced downward, and the movable electrode 2 is simultaneously pushed downward and comes into contact with the fixed electrode 7, thereby becoming energized. Conversely, when the pressure applied to the first insulating sheet 1 is removed, the first insulating sheet 1 and the movable electrode 2 are restored to their original states by the spacer 11, and the gap between the movable electrode 2 and the fixed electrode 7 is conduction is interrupted.

As described above, by applying or removing pressure from the top of the first insulating sheet 1 using the writing instrument P, both electrodes 2 and 7 become in a conductive state or a non-conductive state, and this state is detected by an external circuit. By doing writing instrument P
The XY coordinates of the position can be detected. That is,
Both electrodes 2 and 7 are configured to have a uniform resistance distribution, and as shown in FIG. 10, this transparent flat switch is connected to a constant current source S to determine the current ratio flowing into both movable leads 3 and 4. (X coordinate) and the current ratio (Y coordinate) flowing out from both fixed leads 8 and 9, and by converting these from analog to digital, the coordinate pressed by the writing instrument P (
The position of X, Y) can be determined using the following formula. X=i2/I×a Y=i4/I×b However, I=i1+i2=i3+i4, where I is the total current, i1 is the current flowing from the first movable lead 3, and i2 is the second movable lead 4. i3 indicates the current flowing out from the first fixed lead 8, and i4 indicates the current flowing out from the second fixed lead 9.

[0007] Note that even if the transparent flat switch is connected to a constant voltage source, the coordinates (X, Y) of the pressed position can be determined in the same manner as the voltage value.

[0008]

[Problems to be Solved by the Invention] The problem to be solved is that in the conventional transparent flat switch as described above, insulating dot spacers 11 are provided in a scattered manner on the fixed electrode 7 by screen printing. 9E, even if pressure is applied to this spacer 11 and its vicinity, both electrodes 2 and 7 cannot be connected, resulting in a dead zone.

One possible way to eliminate such a dead zone E is to make the shape of the insulating dot spacer 11 smaller, but with current screen printing, even if it can be made smaller, the limit is about φ150 μm at most, and this is a fundamental problem. This cannot be a good countermeasure.

[0010] Therefore, there is a method of dispersing and fixing finely shaped particle groups (desirably 50 μm or less in size) on an electrode without using screen printing. However, in this method, since the transparent conductive film serving as the electrode is a thin film, it is easily damaged, and once scratched, the resistance value increases, making it impossible to detect accurate coordinate positions.

[0011] In order to solve such problems,
There is an invention disclosed in Publication No. 105420 "Touch Panel". This invention eliminates the dead zone by providing a thin film made of organic polymer between both electrodes, eliminating the spacer, and utilizing electrical breakdown caused by applying pressure.
Moreover, the purpose is to improve wear resistance. However, in the present invention, the conductive and non-conductive states are achieved by utilizing only the dielectric breakdown caused by pressing the thin film, so if the conductive state is set to be complete, the non-conductive state will be changed. On the other hand, if you set it so that the non-conducting state becomes complete, the conductive state will not be complete.
There was a problem that reliable and stable operation could not be obtained.

The present invention was made in order to solve the above problems, and aims to provide a transparent flat switch that can improve wear resistance, minimize the dead zone, and provide reliable and stable operation. There is.

[0013]

[Means for Solving the Problems] In the transparent flat switch according to the present invention, microscopic particles having insulating properties are dispersed and fixed in one of the opposing electrode sheets, and the other electrode sheet has microscopic particles dispersed and fixed therein. The main feature of the device is that the transparent resistive film is provided with a non-uniform thickness so that the electrodes are partially exposed.

[0014]

[Operation] In the present invention, insulating microscopic particles are dispersed and fixed on one of the opposing electrode sheets, and the film thickness is uneven and there are parts on the other electrode sheet. Since we decided to provide the transparent resistive film so that the electrode is exposed, an insulating state can be achieved between the microscopic particles and the transparent resistive film, and a conductive state can be achieved through both dielectric breakdown and direct contact. The transparent resistive film can prevent fine particles from coming into direct contact with the electrode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 are diagrams showing an embodiment of the present invention, and in each diagram, 21 is a first insulating sheet, for example, a sheet of glass, etc.
Materials such as polyethylene terephthalate, polyethylene naphthalate, polybutylene phthalate, polycarbonate, polyethersulfone, polysulfone, epoxy, and acrylic are used, and they are flexible and can be easily displaced in the thickness direction by pressure applied from the outside. is formed.

One side 21a of this insulating sheet 21
A movable electrode 22 made of a transparent conductive film is provided. This movable electrode 22 is made of, for example, gold, nickel,
Materials such as palladium, chromium, tin oxide, indium oxide, tin, and copper oxide are used, and the surface resistance value is 10 to 104.
Ω/□, visible light transmittance is 30% or more. A first movable lead 23 as a signal extraction electrode is provided at the left end of this movable electrode 22, and a second movable lead 24 facing the first movable lead 23 is provided at the right end. These movable leads 23 and 24 are made of a conductive material such as gold, silver, silver/carbon, carbon, copper, copper/silver, nickel, tin, solder, or aluminum, and their resistance value is the same as that of the movable electrode 22. It is more than 10 times smaller than the resistance value, and is usually made of silver and has a conductivity of 10-4 to 10-5 Ω.
It is about cm.

Furthermore, as shown in FIGS. 2 and 3, the movable electrode 2
A transparent resistive film 25 is provided on the surface other than both movable leads 23 and 24 of No. 2, the surface of which is uneven so that the film thickness is uneven and the electrodes are partially exposed. This transparent resistive film 25 has a surface resistance of 102 to 1013.
Ω/□, and the film thickness is set to 1 μm or less even in the thick part. 26 is the first insulating sheet 21 and the movable electrode 22
, the entire movable electrode sheet in this embodiment, which is composed of movable leads 23 and 24 and a transparent resistive film 25, is shown.

Further, as shown in FIGS. 4 and 5, a fixed electrode 28 made of a transparent conductive film is provided on one side 27a of the insulating sheet 27, and this fixed electrode 28 is similar to the movable electrode 22. It is made of a material, and has a first fixed lead 29 as a signal extraction electrode at its upper end, and a second fixed lead 30 opposite to the first fixed lead 29 at its lower end. In addition, these fixed leads 29, 30
are made of the same material as the movable leads 23 and 24.

The surface of the fixed electrode 28 excluding the fixed leads 29 and 30 has an insulating property and has a size of φ50μ.
Microdot spacers 31 made of fine particles of nylon, polystyrene, polyethylene, Teflon, silica, etc. with a size of less than m are dispersed and fixed. Reference numeral 32 indicates the entire fixed electrode sheet in this embodiment, which is composed of the second insulating sheet 27, the fixed electrode 28, the fixed leads 29, 30, and the microdot spacer 31.

Next, the operation will be explained. When pressure is applied from the outside to the first insulating sheet 21 at the position indicated by the writing instrument P in FIG. The microgap held by the microdot spacer 31 is closed, and pressure is applied to the transparent resistive film 25. The thickness of the transparent resistive film 25 is set to 1 μm or less, and when pressure is applied, dielectric breakdown occurs in this portion, and the movable electrode 22 and the fixed electrode 28 in this portion are electrically connected. That is, by pressing the transparent resistive film 25, tunnel effect, Schottky effect,
Due to the Kohler effect, the insulation of the transparent resistive film 28 itself is broken, or the movable electrode 22 and the fixed electrode 28 are brought into direct contact with each other due to exposed parts of the transparent resistive film 25 where the electrodes are partially exposed. It becomes conductive with a certain resistance value.

[0021] The resistance value at this time is mainly determined by both electrodes 22 and 28.
The surface resistance value of the transparent resistive film 25 constituting the transparent resistive film 2
5 itself, leads 23, 24, 2 forming signal extraction electrodes
Needless to say, it changes with the resistance value of 9 and 30,
Usually it is 2 to 3 kΩ or less. Therefore, both electrodes 22,2
By detecting the resistance value between 8 and 8, the conduction state can be defined.

Since the microdot spacer 31 is finer than the conventional insulating dot spacer 11 (φ150 μm or more), a high resolution of, for example, 4 to 5 pieces/mm can be obtained. That is, the dead zone can be made sufficiently smaller than φ200 μm, and therefore accurate information that follows handwriting can be output. Then, when the pressure applied to the first insulating sheet 21 is removed, the first insulating sheet 21 and the movable electrode 22 return to their original positions, and electrical continuity between the electrodes 22 and 28 is interrupted. , the microdot spacer 31 finally restores the microgap of, for example, 50 μm, and becomes completely non-conductive.

As described above, in this embodiment, the micro-dot spacers 31 having insulating properties are dispersed and fixed on the fixed electrode sheet 32, and the movable electrode sheet 26 has non-uniform film thickness. By providing the transparent resistive film 25 in such a way that the electrodes are partially exposed,
Even if the thickness of the transparent resistive film 25 in contact with the microdot spacer 31 is 1 μm or less, a good insulation state can be maintained when no pressure is applied. When connected, tunnel effect, Schottky effect, and Kohler effect occur, allowing accurate conduction to be achieved. In addition, the transparent resistive film 25 is used as an electrode 22 made of a thin film of several thousand A degrees or less.
By providing the electrode 22 over the entire surface, the electrode 22 can be sufficiently protected.

[0024] In the above embodiments, an analog type switch configuration (a type with uniform electrodes on the entire surface) was explained, but it may be a digital type (a type with patterned electrodes) or a digital/analog type. It goes without saying that a combination can also be implemented in the same way. Furthermore, although the present invention has been described with respect to a transparent flat switch, it goes without saying that this invention is particularly meaningful for transparent flat switches, and is applicable to all flat switches of this type.

[0025]

Effects of the Invention As explained above, in the transparent flat switch of the present invention, microscopic particles having insulating properties are dispersed and fixed in one electrode sheet of the opposing electrodes, and By providing a transparent resistive film with uneven film thickness and partially exposing the electrode, it is possible to improve wear resistance and minimize the dead zone, as well as ensure reliable and stable operation. It has advantages such as being inexpensive and allowing for a large area.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a plan view showing the structure of the movable electrode sheet shown in FIG. 1.

FIG. 3 is a sectional view showing the XX cross section of the movable electrode sheet shown in FIG. 2;

4 is a plan view showing the structure of the fixed electrode sheet shown in FIG. 1. FIG.

5 is a sectional view showing a Y-Y cross section of the fixed electrode sheet shown in FIG. 4. FIG.

FIG. 6 is a sectional view showing the configuration of a conventional transparent flat switch.

7 is a diagram for explaining the movable electrode sheet shown in FIG. 6. FIG.

8 is a diagram for explaining the fixed electrode sheet shown in FIG. 6. FIG.

FIG. 9 is a diagram showing the operation of a conventional transparent flat switch.

FIG. 10 is a perspective view illustrating a method for detecting coordinate positions in a flat switch.

[Explanation of symbols]

21 First insulation sheet 22 Movable electrode 25 Transparent resistive film 26 Movable electrode sheet 27 Second insulation sheet 28 Fixed electrode 31 Microdot spacer 32 Fixed electrode sheet

Claims (2)

[Claims] Claim 1: Of the opposing electrode sheets, microscopic particles having insulating properties are dispersed and fixed on the electrode surface of one electrode sheet, and the film thickness is uniform on the electrode surface of the other electrode sheet. A transparent flat switch characterized by having a transparent resistive film provided in such a way that the electrode surface is uniform and partially exposed. Claim 2: The size of the finely shaped particles is φ50.
μm or less, and the transparent resistive film has a maximum thickness of 1 μm.
The following is a transparent flat switch characterized by having a surface resistance of 102 to 1013 Ω/□.