JPH04289620A - Flat switch - Google Patents

Abstract

PURPOSE:To obtain a high-resolution handwriting flat switch which has no coordinate omission and enables continuous input. CONSTITUTION:An insulation thin film 12 which has the electrode formed of a number of small-area coating portions to form an up-and-down surface with the maximum film thickness difference being smaller than the grain size of a microdot spacer 13 to correspond to high resolution, or a conductive thin film 12 which has the electrode coated all over or in part to form a similar up-and-down surface, is provided for surface treatment on a fixed electrode 7 out of two opposite electrodes to disperse and fix thereon the insulation microdot spacer 13 which is formed of sufficiently small grains to correspond to high resolution.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat switch in which contacts are opened and closed by displacing an electrode sheet with a pen touch, and particularly relates to a high-resolution flat switch.

0002

2. Description of the Related Art Hitherto, as a flat switch of this type, the one shown on page 170 of ``Key Points of Input Device Development, Design, and Application'' published by Japan Industrial Technology Center is known.

This flat switch is shown in FIGS. 11 to 17. Figure 11 is a configuration diagram of the flat switch, and Figure 1
2. FIG. 13 is a plan view and a cross-sectional view of the movable electrode sheet, respectively, FIGS. 14 and 15 are a plan view and a cross-sectional view of the fixed electrode sheet, respectively, and FIG. 16 is an explanatory diagram of the operation of the flat switch. 17 is an equivalent circuit diagram illustrating the coordinate detection situation. In each figure, 1 is a first insulating sheet that is easily displaced in the thickness direction due to stress, 2 is a movable electrode formed of a conductive film and provided on one side of the first insulating sheet 1, and 3 is a movable electrode. 2, a first movable lead which is one of the signal extraction electrodes; 4, a second movable lead which is the other signal extraction electrode of the movable electrode 2; 5, the first insulating sheet 1, the movable electrode 2 and the first movable lead; , second movable leads 3, 4
This is a movable electrode sheet composed of.

6 is a second insulating sheet corresponding to the first insulating sheet 1; 7 is a fixed electrode formed of a conductive film and provided on one side of the second insulating sheet 6; 8 is this fixed electrode; The first fixed lead is one signal extraction electrode of the electrode 7, 9 is the second fixed lead which is the other signal extraction electrode of the fixed electrode 7, 10 is the second insulating sheet 6, the fixed electrode 7 and The fixed electrode sheet 11 composed of both fixed leads 8 and 9 is made of an insulating material such as silicone, acrylic, epoxy, polyester, urethane resin, etc., and is provided on the fixed electrode 7 by screen printing or the like.The fixed electrode sheet 11 has a diameter of 150 mm. ~500 μm, showing insulating dot spacers with a height of approximately 10% of the diameter.

Next, the operation will be explained. As shown in FIG. 11, in the flat switch, when the first insulating sheet 1 is pressed with a writing instrument P such as a finger or a ballpoint pen, the movable electrode 2 moves downward together with the first insulating sheet 1, and the movable electrode 2 and the fixed electrode 7 comes into contact and becomes energized.

Next, when the external stress applied to the first insulating sheet 1 decreases, the first insulating sheet 1 and the movable electrode 2 begin to return to their original states, and eventually the movable electrode 2 and the fixed electrode 7 become non-contact. A conductive state is established, and the first insulating sheet 1 and movable electrode 2 return to their original states.

As described above, by applying or removing external stress to the first insulating sheet 1, both the electrodes 2 and 7 become conductive or non-conductive, and this state can be detected by an external circuit. Can be done. Furthermore, both electrodes 2,
7 is configured to have a uniform resistance distribution, so
For example, as shown in FIG. 17, a flat switch is connected to a constant current source S, and the current ratio (
X coordinate) and the current ratio flowing out from both fixed leads 8 and 9 (
The coordinates (X, Y) of the pressed position can be determined from the following equation by converting these from analog to digital.

[0008] Total current i1 Inflow current i2 from the first movable lead 3 Inflow current i3 from the second movable lead 4 Outflow current i4 from the first fixed lead 8 Outflow current from the second fixed lead 9 Note that the flat switch Even if it is connected to a constant voltage source, the coordinates (X, Y) of the pressed position can be found in the same way.

[0009]

[Problems to be Solved by the Invention] Since the conventional flat switch has the insulated dot spacer 11 on the fixed electrode 7 as described above, as shown in FIG. The electrodes 2 and 7 cannot contact each other and a dead zone E occurs. This dead band E is
The smaller the shape of the insulating dot spacer, the smaller it can be, but in conventional flat switches, the insulating dot spacer 11 is formed using thick film technology such as screen printing, so the minimum limit is about 150 μm, which makes it difficult to achieve high resolution. It is not possible to form a flat switch with As a countermeasure to this problem, a method of dispersing and fixing a group of minute particles on the electrode to form a spacer can be considered, but this method has two problems. One is that the microparticles easily fall off from the electrode and no longer function as a spacer.The other is that when these microparticles come into contact with the electrode during pressing, they damage the electrode, resulting in damage to the electrode. The resistance value increases and becomes non-uniform, making accurate coordinate detection impossible.

The present invention has been made to solve these problems, and its object is to extremely reduce the dead band E with a simple configuration and obtain a high-resolution flat switch. In addition, the present invention aims to prevent the microparticle spacers from falling off from the electrodes, prevent damage to the electrodes due to the microparticle spacers, and obtain a flat switch with improved durability.

[0011]

[Means for Solving the Problems] The flat switch of the present invention uses a thin film technique such as photolithography as a base treatment on at least one of the electrodes, so that the electrode coating part is compatible with high resolution and has a large number of small Either an insulating thin film with an uneven surface where the maximum film thickness difference between the covered areas is smaller than the particle diameter of the microdot spacer, or a conductive film with a similar surface unevenness that covers the entire electrode or a part of the electrode. A thin film is provided, and insulating microdot spacer particles made of sufficiently small particles having a shape that can support high resolution are dispersed and fixed on the thin film. Further, a conductive thin film is provided on an electrode opposite to an electrode in which microdot spacer particles are dispersed and fixed.

0012

[Operation] The flat switch configured as above is
Microdot spacer particles, which are microparticles introduced between the electrodes, act as spacers and can perform conducting and non-conducting operations in the same way as in the conventional technology.
In the case of the present invention, since the microdot spacer is a minute particle and the electrode covering part of the insulating thin film underlying the spacer has a small area, the dead zone E that occurs when pressing can be sufficiently small, and high resolution coordinates can be obtained. Detection becomes possible. In addition, since the microdot spacer particles are dispersed and fixed on a thin film with surface irregularities smaller than the particle diameter of the microdot spacer, the contact area can be increased while maintaining the spacer function, increasing adhesion and preventing falling off. is possible. Furthermore, the electrode of a flat switch is a thin film with a thickness of several hundred nanometers, and if damage occurs due to direct contact with spacer particles during pressing, the resistance value will increase and become uneven, making accurate coordinate detection impossible. do. The conductive thin film provided on the electrode opposite to the electrode on which the microdot spacer particles are fixed is made thicker than the above electrode,
Eliminates direct contact with microdot spacer particles,
Damage to the electrode can be prevented.

[0013]

[Example] Example 1. An embodiment of the present invention is shown in FIGS. 1 to 5. Figure 1 is a configuration diagram of a transparent flat switch.
2 and 3 are a plan view and a cross-sectional view of the movable electrode sheet, respectively, and FIGS. 4, 5 (a), and (b) are a plan view, a cross-sectional view, and a partial enlarged view of the cross-section of the fixed electrode sheet, respectively. It is. 1, 2, and 3, 1 is made of a material that easily changes in the thickness direction due to stress, such as glass, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate, polyethersulfone, polysulfone, epoxy, or acrylic. This is a transparent first insulating sheet.

Reference numeral 2 denotes a movable electrode formed of a transparent conductive film on one side of the first insulating sheet 1. The movable electrode 2 is made of, for example, gold, nickel, palladium, chromium, tin oxide, indium oxide, tin, or copper iodide, and has a surface resistance of 10 to 104 Ω/□ and a visible light transmittance of 30.
% or more.

Reference numeral 3 denotes a first movable lead as a signal extraction electrode provided at one end of this movable electrode 2, and 4 indicates a second movable lead opposite to the first movable lead 3 provided at the other end. It is. These movable leads are formed using a conductive material such as gold, silver/carbon, carbon, aluminum, copper, silver/copper, nickel, tin, or solder. This resistance value is 1 with respect to the resistance value of the above electrode material.
/10, and is usually made of silver and has an electrical conductivity of 10-4 to 10-5 Ω·cm. And the above first
A movable electrode sheet 5 is formed by the insulating sheet 1, the movable electrode 2, and the movable leads 3 and 4.

In FIGS. 1, 4, and 5, reference numeral 6 indicates a transparent second insulating sheet corresponding to the first insulating sheet 1, and is made of the same material as the first insulating sheet.

A fixed electrode 7 is formed of a transparent conductive film on one side of the second insulating sheet 6, and is made of the same material as the movable electrode 2. 8 is a first fixed lead as a signal extraction electrode provided at one end of this fixed electrode 7, 9 is a second fixed lead opposite to the first fixed lead 7 provided at the other end, In terms of material, the first and second
This is similar to the movable leads 3 and 4 of .

Reference numeral 12 denotes a large number of small holes provided on the surface of the fixed electrode 7 excluding the fixed leads 8 and 9, which have irregularities with a maximum film thickness difference of 5 μm or less, and are provided so that the electrodes are partially exposed. It is an insulating transparent thin film consisting of a covering area of 13
is a microdot spacer, which is a fine particle with a diameter of 50 μm or less and has an insulating property and is dispersed and fixed on this transparent thin film.

The microdot spacer 13 is made of a particulate material such as nylon, polystyrene, polyethylene, Teflon, or silica. Then, the second insulating sheet 6, fixed electrode 7, fixed leads 8, 9
, the thin film 12 and the microdot spacers 13 form a fixed electrode sheet 10.

In the transparent flat switch constructed as described above in FIG. 1, when external pressure is applied to the first insulating sheet 1, the first Insulating sheet 1 is displaced. And a movable electrode 2,
The fixed electrode 7 exposed from the insulating transparent thin film 12 makes electrical contact and has a stable resistance value. It goes without saying that this value mainly changes depending on the surface resistance value of the transparent conductive film that makes up both electrodes 2 and 7, and the resistance value of the leads that make up the signal extraction electrode, but it is usually 2 to 3 KΩ or less. be. By detecting this stable resistance value between both electrodes 2 and 7, the conduction state can be defined. On the other hand, when the external stress decreases, the contact resistance increases first, and then a steady-state microgap occurs, resulting in non-conduction.

The microdot spacer 13 is a conventional insulating dot spacer 1 with a diameter of 150 μm to 500 μm.
1, and since the insulating transparent thin film 12 also consists of a correspondingly fine coating, the dead zone can be made sufficiently smaller than φ200 μm, for example,
It can fully support high resolution of 4 to 5 lines/mm. In addition, since the transparent thin film 12 has minute irregularities with a maximum film thickness difference of 5 μm or less, the adhesion of the microdot spacers 13 dispersed and fixed thereon is strong, and the spacers are stable without falling off. Functionality can be maintained.

[0022] In the above embodiments, the switch configuration is analog type (uniform electrodes on the entire surface), but it can also be digital type (patterned electrodes) or digital/analog type (input part digital, detection part analog). The same applies to the combination of In addition, in the above example, a case was described in which an insulating transparent thin film was used as a base treatment for the electrode, but when a conductive transparent thin film is used, the electrode covering is limited to a small area of the covering part. Since it is not necessary, manufacturing becomes easy.

Example 2. 6 to 10 show another embodiment of the present invention. FIG. 6 is a block diagram of a transparent flat switch, FIGS. 7 and 8 are a plan view and a sectional view of a movable electrode sheet, and FIGS. 9 and 10 are a plan view and a sectional view of a fixed electrode sheet. In addition, 1 to 10 and 13 are
This is exactly the same as Example 1 above.

In the figure, 14 indicates a surface resistance of 102 to 1 provided on the surface of the movable electrode 2 excluding both movable leads 3 and 4.
10μ transparent conductive paint with a resistance value of 013Ω/□
It is a transparent conductive thin film coated to a thickness of less than m. In this example, the transparent conductive thin film 14 is provided on the surface of the movable electrode 2 excluding both movable leads 3 and 4, and the same microdot spacer 13 as in Example 1 is provided on the surface of the fixed electrode excluding both fixed leads. has been established.

The operating characteristics of this embodiment are similar to those of embodiment 1, but the transparent conductive thin film 14 is provided on the surface of the movable electrode 2 made of a thin film of several hundred nm or less, and the microdot spacer 13 It has a great protection effect against damage to the electrode caused by. Further, the present transparent conductive thin film 14 has a pressure-sensitive property in which the contact resistance changes depending on the pressing force, and has the effect of improving the insulation between the electrodes 2 and 7 when non-conducting. That is, it shows a stable contact resistance value when the pressing force is several tens of grams or more,
If the pressing force is less than that, there will be a large resistance.

In addition to this embodiment, a transparent thin film treatment similar to the first embodiment may be applied to prevent the microdot spacers 13 from falling off the fixed electrodes 7. In addition to the above-mentioned analog system (uniform electrodes over the entire surface), the switch configuration may be a digital system (patterned electrodes), a digital/analog system (digital input section, analog detection section), or a combination thereof.

Further, in the first and second embodiments, the structure of the flat switch is described as a transparent flat switch made of a transparent material, but the present invention is not limited to a transparent flat switch made of a transparent material as long as it conforms to the spirit of the present invention.

[0028]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the effects described below.

By dispersing and fixing microdot spacers made of insulating microparticles as electrode spacers, the dead zone can be reduced and a high-resolution flat switch without missing coordinates and capable of continuous input can be realized.

Furthermore, since the microdot spacers are dispersed and fixed on the thin film provided on the electrode, which has an uneven surface smaller than the particle diameter, the adhesion is improved and it is possible to prevent them from falling off.

Furthermore, a conductive thin film for protecting the electrode is provided on the opposite electrode to the electrode provided with the microdot spacer to prevent damage to the electrode due to direct contact between the microdot spacer particles and the electrode, thereby enabling accurate coordinate detection. do.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a transparent flat switch showing a first embodiment of the present invention.

FIG. 2 is a plan view of a movable electrode sheet showing Example 1 of the present invention.

FIG. 3 is a cross-sectional view of a movable electrode sheet showing Example 1 of the present invention.

FIG. 4 is a plan view of a fixed electrode sheet showing Example 1 of the present invention.

FIG. 5 is a sectional view of a fixed electrode sheet showing Example 1 of the present invention.

FIG. 6 is a configuration diagram of a transparent flat switch showing a second embodiment of the present invention.

FIG. 7 is a plan view of a movable electrode sheet showing Example 2 of the present invention.

FIG. 8 is a sectional view of a movable electrode sheet showing Example 2 of the present invention.

FIG. 9 is a plan view of a fixed electrode sheet showing Example 2 of the present invention.

FIG. 10 is a sectional view of a fixed electrode sheet showing Example 2 of the present invention.

FIG. 11 is a configuration diagram of a conventional flat switch.

FIG. 12 is a plan view of a conventional movable electrode sheet.

FIG. 13 is a sectional view of a conventional movable electrode sheet.

FIG. 14 is a plan view of a conventional fixed electrode sheet.

FIG. 15 is a sectional view of a conventional fixed electrode sheet.

FIG. 16 is an explanatory diagram of the operation of a conventional flat switch.

FIG. 17 is an explanatory diagram of a coordinate detection situation of a conventional flat switch.

[Explanation of symbols]

1 First insulation sheet 2. Movable electrode 6 Second insulation sheet 7 Fixed electrode 12 Thin film 13 Microdot spacer 14 Conductive thin film

Claims (2)

[Claims] 1. A first insulating sheet, a movable electrode provided on one side of the main insulating sheet, a second insulating sheet, and a fixed electrode provided on one side of the main insulating sheet and facing the movable electrode. A microdot spacer made of small insulating particles separating the two electrodes is dispersed on a thin film having an uneven surface smaller than the particle diameter of the microdot spacer provided on at least one of the electrodes. , a flat switch characterized by being fixed. 2. A first insulating sheet, a movable electrode provided on one side of the main insulating sheet, a second insulating sheet, and a fixed electrode provided on one side of the main insulating sheet and facing the movable electrode. , a flat switch characterized by comprising a microdot spacer made of small insulating particles provided on one of the electrodes, and a conductive thin film provided on the other electrode.