JPH0355019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a keyboard switch, more specifically, a first plastic sheet on which a contact portion is formed, and a contact point corresponding to the contact portion of the first plastic sheet. a second plastic sheet having a contact portion formed thereon, and a contact portion forming surface of at least one of both plastic sheets such that the opposing contact portions of both plastic sheets maintain a non-contact state without being pressed. The present invention relates to a keyboard switch in which an insulating spacer layer is formed except for the contact portion.

[Technical background of the invention]

Keyboard switches of the type described above are known.
3 to 5 show an example of such a known keyboard switch. This keyboard switch consists of a first plastic sheet 10a and a second plastic sheet 1 as shown in FIG.
0b and one common plastic sheet 10
This is obtained by bending the material at the bending portion 16. The first plastic sheet 10a has an appropriate number of contacts 11 spaced at appropriate intervals, and a conductive circuit 15 leading to the contacts 11 and a terminal 13 formed in a terminal portion 10c connected to the first plastic sheet 10a. is formed. The second plastic sheet 10b includes a plastic sheet 10
A contact point 12 is provided which faces the contact point 11 when the contact point 11 is bent at the bending portion 16. This contact point 12
A conductive circuit 14 connecting terminals 13 and 13 is formed in both plastic sheets 10b and 10a.

The plastic sheet 10 is made of a thermoplastic or thermosetting soft and resilient plastic material, such as polyester resin, and is often about 50 to 300 microns thick.

The contacts 11 and 12, the conductive circuits 14 and 15, and the terminal 13 are formed by applying a conductive paint and curing it by an appropriate method such as heat curing or ultraviolet curing, and the thickness thereof is usually about 5 to 30 microns. be.

As shown in FIG. 4, an insulating spacer layer 17 is provided on the contact formation side of at least one of the plastic sheets 10a, 10b (in the illustrated case, only the second plastic sheet 10b). This spacer layer 17 is applied to a portion other than the contact 12 so that the contact 12 is exposed, for example, with a thickness of 50 to 500.
It has a thickness of about microns and is formed by a paint application method such as screen printing, and then hardened.

The plastic sheet 1 shown in Fig. 4 has each contact point, conductive circuit, terminal, and spacer layer formed in this way.
0 by 180 degrees with the spacer layer 17 inside at the bending portion 16 as shown in FIG.
A keyboard switch is constructed in which contacts 11 and 12 of contacts a and 10b face each other with an insulating distance maintained by a spacer layer 17. Note that the first plastic sheet 10a and the spacer layer 17 can be fixed by chemical means such as adhesion or heat fusion, or mechanical means such as screws.

In the example shown in FIGS. 3 to 5, the first and second plastic sheets 10a, 10b are obtained by folding one plastic sheet 10, but both plastic sheets 10a, 10b are separately formed. It can also be made separately.

Although the keyboard switch shown in FIGS. 3 to 5 described above has a structure in which contact circuits 15 and 14 are formed on both plastic sheets 10a and 10b, respectively, a keyboard switch having a different structure is shown in FIG. In this keyboard stitch, among the first plastic sheet 10a and the second plastic sheet 10b which are separately made, the contact points 11a formed on the first plastic sheet 10a having the terminal portions 10c are formed in half. The second plastic sheet 10b is separated into two circular parts and connects the contact circuits 15 connected to the terminals 13, respectively.
When the contact 12 formed in is pressed, it bridges the two separated contact parts of the opposing contact 11, thereby forming a contact 13 that is connected to the two contact parts.
The second plastic sheet 10b is not provided with a contact circuit. Both plastic sheets 10 in Figure 7
When making a keyboard switch using parts a and 10b, a spacer layer is interposed between both plastic sheets and the keyboard switch is completed by the same process as shown in FIGS.

When forming the spacer layer 17 on the plastic sheet 10 by screen printing in the keyboard switch made as described above,
Conventionally, solid printing is used. Therefore, as shown in FIG. 6, the resulting coating film thickness tends to be unevenly thick at the edge portions and thinner at the non-edge portions, that is, the central portion. This characteristic causes a large difference in film thickness, especially due to the difference in the plane size of the film, that is, the difference between a thin pattern width and a wide pattern width. Despite these circumstances, in order to make the spacer film thickness uniform, it is necessary for craftsmen to check the squeegee pressure and speed during printing, the hardness of the squeegee material, the emulsion thickness of the silk screen mesh, the paste viscosity, etc. Although highly artistic techniques were required, the product yield was still not very good. In particular, non-uniformity in the spacer film thickness around the contacts will significantly degrade the quality of the keyboard switch.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a keyboard switch equipped with a means for forming a constant spacer film thickness especially around the contact points.

[Summary of the invention]

In order to achieve the above object, the present invention includes a spacer layer that includes a relatively narrow first spacer region formed to surround the contact portion and a region outside the first spacer region. and a second spacer region formed at a slight distance from the first spacer region.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to FIGS. 1 and 2.

Fig. 1 and Fig. 2 show an embodiment in which the basic structure of the keyboard switch shown in Figs. 3 to 5 is adopted as is, and the same reference numerals indicate the same components, and the explanation thereof will be omitted. . 1st
The figure corresponds to FIG. 4 already mentioned.
The spacer layer 17 in FIGS.
2, a relatively narrow first spacer region 1 formed at a slight distance from the contact point 12 so as to surround the contact point 12;
7a and a second spacer region 17b formed at a slight distance from the spacer region 17a so as to cover the outside of this spacer region. , 4th
It is no different from the one in the picture.

Since the first spacer regions 17a can be formed in a relatively thin pattern, it is easy to control the thickness of the spacer layer, especially for each spacer region 17a corresponding to each contact point 12.
By making the pattern width constant, it is easy to form a spacer layer with a constant thickness.

In the above-mentioned embodiment, the case where the planar shape of the contact point is circular is illustrated, and therefore the case where the first spacer region 17a is ring-shaped has been described, but the shape thereof is limited to circular. However, it can also be implemented in other shapes, for example square or oval.

Further, the present invention can also be applied to a keyboard switch in which the spacer layer is formed by a method other than screen printing, and the same effects can be achieved.

In the above, an embodiment has been described in which the present invention is applied to a keyboard switch of the type shown in FIGS. It goes without saying that the present invention can be applied in exactly the same way to a keyboard switch of the type shown in Figure 1, in which a contact circuit is formed only on one plastic sheet.

Implementation data Using a commercially available room temperature vulcanizable silicone resin varnish,
As shown in FIGS. 1 and 2, a ring-shaped first spacer region 17a with a width of about 1.5 mm is provided at a slight distance from the contact 12 so as to surround the contact 12.
and a second spacer region 17b with a thickness of about 100 μm at a distance of about 1 mm from the spacer region 17a so as to cover the outside of this spacer region, and then printed at 150° C. for 30 minutes. A curing treatment was performed to form a spacer layer 17. The thickness of the spacer layer was measured for spacer region 17a and was found to be 65 to 115 microns.

Comparative Example Data A hole having a diameter of 12 mm was formed in the spacer layer 17 as shown in FIG. 4 to surround the contact point 12 in the same manner as in the above example. The thickness of this spacer layer 17 was measured at the periphery of the contact 12 (edge part of the spacer layer) and was 85 to 175μ.
The thickness was non-uniform compared to the above embodiment of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, by forming a relatively narrow spacer region surrounding the contact, the thickness of the spacer film around the contact can be easily made constant by screen printing. Therefore, high quality keyboard switches can be manufactured at a high yield.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of the manufacturing process of the keyboard switch of the present invention, FIG. 2 is a sectional view of the device shown in FIG. 1, and FIGS. 3 and 4 are different manufacturing steps of the conventional keyboard switch. FIG. 5 is a side view showing the completed state of the keyboard switch shown in FIGS. 3 and 4; FIG. 6 is a sectional view of the main parts of the keyboard switch shown in FIG. 5; FIG. 3 is a plan view showing a manufacturing process of a conventional keyboard switch, which is different from that shown in FIG. 3. FIG. 10a...first plastic sheet, 10b
...Second plastic sheet, 11, 12...
Contact, 13... terminal, 14, 15... conductive circuit,
17... Spacer layer, 17a... First spacer region, 17b... Second spacer region.

Claims (1)

[Scope of Claims] 1. A first plastic sheet having contact portions formed thereon, and a second plastic sheet having contact portions corresponding to the contact portions of the first plastic sheet formed thereon, the plastic sheet having both the plastic sheets An insulating spacer layer is formed on the contact forming surface of at least one of both plastic sheets, except for the contact portion, so that the opposing contact portions maintain a non-contact state without being pressed. In the keyboard switch, the spacer layer includes a relatively narrow first spacer region formed to surround the contact portion, and a first spacer region covering an outer region of the first spacer region. and a second spacer region formed at a certain distance from the keyboard switch.