JPS6235228Y2 - - Google Patents

Description

[Detailed Description of the Invention] Field of Application of the Invention The present invention relates to a circuit board for a switch, and in particular to an improved structure of its contact portion.

BACKGROUND ART FIG. 1 shows a circuit board for a conventional membrane switch of this kind, in which 1 is a flexible insulating film such as polyester, 2, 3 and 2', 3' are A plurality of contact portions made of silver paste or the like provided at opposite ends of the dotted line Y-Y′ and housed in a hole of an insulating spacer to be described later, each having an outer diameter smaller than the outer diameter of the hole; 4. 4' is a lead connected to these contact parts 2, 3..., and the end 4a of the lead 4, 4' is connected to the insulating film 1.
A connector is connected to the protrusion 1a by an appropriate method. Moreover, this insulating film 1 is indicated by the dotted line Y-
It is bent into an overlapping shape from Y', an insulating spacer (not shown) is interposed in the middle, and the contact part 2 faces 2' and the contact part 3 faces 3' in the hole formed in the insulating spacer. Insulated substrate (not shown)
It is fixed on top to form a circuit board for a membrane switch.

Problems to be solved by the invention However, in the conventional example mentioned above, the contact portions 2, 3...
Since the entire surface of the . Silver paste had the disadvantage of being corroded by sulfurization and having a short lifespan. In addition, the distance between the upper and lower contacts, that is, the operating stroke of the switch, is determined by subtracting the thickness of the contact from the thickness of the insulating spacer. It was necessary to increase the thickness of the spacer, and it was necessary to use an insulating spacer that was expensive and difficult to work with.

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional example, and to provide a circuit board for a switch that is inexpensive, easy to operate, and highly reliable.

Means for Solving the Problems In order to solve the problems of the above-mentioned conventional example, the present invention provides a flexible insulating film that is double-folded with an insulating spacer sandwiched between the holes in the insulating spacer. A pair of electrodes are provided on the film surfaces facing each other with the insulation film exposed at the center of the electrodes. A conductive film is formed so that the carbon conductive film on the exposed portion serves as a contact point of the switch, and the electrode is located at a position overlapping with the insulating spacer, and the electrode, the carbon conductive film on the electrode, and the insulating spacer are connected to each other. The structure was designed to overlap.

Embodiment Hereinafter, the present invention will be explained in detail based on FIGS. 2 to 4. 5 is a dotted line Y in FIG.
This electrode is located at the position of the contact parts 2 and 3 on one side of -Y′, and this electrode 5 is formed by printing silver paste on one side of the flexible insulating film 1. Inside, there is an exposed portion 7 where the insulating film 1 remains exposed.

A contact 8 made of a carbon conductive film with low specific resistance is formed on the exposed portion 7, and the carbon conductive film extends from the contact 8 to cover the electrode 7.
This contact 8 and the electrode 5 constitute a contact portion.

6 is a lead connected to the electrode 5, and the lead 6 is also covered with a carbon conductive film.

On the other hand, at the positions of the contact portions 2' and 3' on the other side of the dotted line Y-Y' in FIG.
An electrode 5' and a contact 8' are formed in the same manner as the contact 8.

Then, as shown in FIG.
are folded in a superimposed manner along the dotted line Y-Y' in FIG. constitutes a switch circuit board, and this switch circuit board is
When the electrodes 5, 5' and the contacts 8, 8', which face each other at the top and bottom, face each other through the hole 11 of the insulating spacer 9, and press the insulating film 1 with the finger 12,
Contacts 8 and 8' are in contact to connect electrodes 5 and 5'.

The outer shape of the electrodes 5, 5' is larger than the outer shape of the hole 11 of the insulating spacer 9, so that the electrodes 5, 5', the carbon conductive coating on the electrodes 5, 5', and the insulating spacer 9 are The distance between the upper and lower contacts 8, 8', that is, the operating stroke of the switch, is always limited by the insulating spacer 9.
It is larger than the thickness of.

FIG. 5 shows an example of the application of a contact section consisting of an electrode 5 and a contact point 8, in which the pattern of the electrode 5 is changed to perform various displays.

In this example, the insulating film 1 forming the electrode 5 is
The electrode 5 is made of transparent or translucent synthetic resin material.
The pattern formed by the electrodes 5 can be seen from the side opposite to the side on which the electrodes 5 are formed, and serves as a display section. For example, when silver paste is used for the electrode 5, the black color of the contact 8 of the carbon conductive film and the white color of the silver paste form a very sharp contrast, and the insulating film 1
can be seen through.

The pattern of the electrodes 5 may be a geometrical design such as those shown in A to H in FIG. 5, or alphabets and numbers such as I and J which can be distinguished when inputting letters and numbers, so that the operating functions of the switches can be identified at a glance, or any other suitable design may be adopted, such as the indication for the buzzer function shown in K.

In the example explained above, an example was explained in which silver paste was used as the electrode 5, but it is not limited to only silver paste. Copper paste can also be used, and furthermore, silver paste can be colored arbitrarily. You can also use something.

Effects of the Invention As described above, according to the present invention, a flexible insulating film that is double-folded with an insulating spacer sandwiched between the insulating spacers is attached to the opposing film surfaces through the holes in the insulating spacer. , a pair of electrodes is provided in a shape that leaves an exposed part with an insulating film exposed at the center of the electrode, and a carbon conductive film with low specific resistance is formed on the electrode and the exposed part to form the exposed part. The upper carbon conductive coating is used as a contact point of the switch, and the electrode is located at a position overlapping the insulating spacer, and the electrode, the carbon conductive coating on the electrode, and the insulating spacer are overlapped. , contacts that were previously formed only from precious metals such as silver can now be formed using an inexpensive carbon conductive film, and by arranging electrodes made of a small amount of silver paste around the carbon conductive film, the actual switch function is eliminated. The structure can be made comparable to the above, and has the effect of increasing the contact area while saving precious metals, and further has a structure in which the electrode, the carbon conductive film on the electrode, and the insulating spacer are overlapped. Therefore, in addition to saving precious metals and preventing sulfurization of precious metals such as silver by covering the surface of precious metals with the carbon conductive film, the operating stroke of the switch can be increased without requiring any other configuration. In other words, the operational effect of the switch can be improved, and the functionality of the switch can be improved while reducing material costs with an overall simple configuration, which is a remarkable practical effect. . Furthermore, since the shape of the contact portion can be patterned arbitrarily, it is also possible to display the contact portion.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conventional circuit board for a switch, Figures 2 to 4 relate to the circuit board for a switch according to the present invention, Figure 2A is a plan view of an insulating film with electrodes provided, and Figure B is a sectional view of the same, FIG. 3 shows the structure of the contact part, FIG. FIG. 5 is a back view showing an example of a pattern of a contact portion according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Insulating film, 5... Electrode, 7... Exposed part, 8... Contact, 9... Insulating spacer, 11...
hole.

Claims (1)

[Claims for Utility Model Registration] (1) A flexible insulating film that is double-folded with an insulating spacer sandwiched in the middle, and a pair of flexible insulating films on the film surfaces facing each other across the holes in the insulating spacer. An electrode is provided in a shape that leaves an exposed part with an insulating film exposed at the center of the electrode,
forming a carbon conductive film with a low specific resistance on the electrode and the exposed part, and using the carbon conductive film on the exposed part as a contact point of the switch, and positioning the electrode at a position overlapping with the insulating spacer; A circuit board for a switch, characterized in that the electrode, the carbon conductive film on the electrode, and the insulating spacer are overlapped. (2) The circuit board for a switch according to claim (1), wherein the insulating film is made of a transparent or translucent synthetic resin material.