JPH07326251A - Key top plate of push button switch - Google Patents

Abstract

PURPOSE:To provide a key top plate without any warp generated even when a frame body is molded in a film plate. CONSTITUTION:A key top 20 is formed by molding mold resin 23 in a film plate composed of a resin film having flexibity and a frame body 25 made of mold resin (25-1 to 25-12) is formed surrounding the key top 20. In this case, the frame body 25 is separated into twelve frame parts 25-1 to 25-12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key top plate of a push button switch.

[0002]

2. Description of the Related Art Conventionally, as electronic devices have become smaller and thinner,
There is also a demand for downsizing and thinning of the key top plate of the push button switch used for the operation section.

FIGS. 6A and 6B are views showing a conventional key top plate 80 which meets such a demand. FIG. 6A is a plan view and FIG. 6B is a sectional view taken along the line aa in FIG. 6A. FIG. 3C is a plan view of a film plate 81 used for the key top plate 80.

As shown in the figure, a conventional key top plate 80
Is a film plate 8 made of a flexible resin film.
1, and six key tops 83 made of molded resin are molded in the film plate 81, and the key tops 83
A frame 85 made of a mold resin is molded around the circumference of.

Here, the key tops 83 are formed above and below the through holes 87 formed in the film plate 81,
Further, the frame body 85 is also integrally formed above and below the through hole 89 provided in the film plate 81.

The reason why the frame 85 is provided here is to provide a predetermined space with a switch substrate (not shown) arranged below the key top plate 80 (spacer function), and the film plate 81 serves as a pin. It is for stretching, and also the frame 85
The projection 91 provided on the lower surface of the key top plate 83
For positioning and fixing.

When a switch substrate (not shown) is arranged under the film plate 81 and the key top 83 is pressed, the lower surface of the key top 83 turns on the switch contact of the switch substrate.

[0008]

However, the conventional key top plate 80 has the following problems.
That is, when the frame body 85 is molded on the film plate 81, high heat is applied to both, but the linear expansion coefficient of the film plate 81 and the frame body 8
Since the linear expansion coefficients of 5 are different, there is a risk that the key top plate 80 may warp when they are cooled.

For example, PETP as the film plate 81
(Polyethylene terephthalate) and PMMA (polymethylmethacrylate) as the molding resin, and the length l in the longitudinal direction of the frame 85 shown in FIG. Mold temperature 80 ℃
When cooled to 20 ° C, the film plate 81 is about 0.10.
The frame body 85 contracts about 0.65 mm. That is, since the contraction lengths of the two are quite different, the key top plate 80
Warpage occurs.

The present invention has been made in view of the above points, and an object thereof is to provide a key top plate which does not warp even when a frame is molded on a film plate.

[0011]

In order to solve the above problems, the present invention forms a key top by molding a mold resin on a film plate made of a flexible resin film,
Further, in the key top plate of the push button switch in which a frame made of a mold resin is molded so as to surround the periphery of the key top,
The frame body is separated at a plurality of locations.

[0012]

Since the frame body is separated at a plurality of points, when the frame body is molded on the film plate and when it cools due to high heat, it separates even if the amount of shrinkage of the two differs due to the difference in linear expansion coefficient between the two. Since the fixing length of each part of the frame body to the film plate is short, there is no fear that the key top plate warps.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1A and 1B are views showing a structure of a key top plate 1 according to one embodiment of the present invention, wherein FIG. 1A is a perspective view of a front surface side, FIG. 1B is a perspective view of a back surface side, and FIG. 3C is a side view, and FIG. 3D is a sectional view taken along the line AA of FIG.

As shown in the figure, the key top plate 1 is
Six key tops 20 are formed in series in a rectangular film plate 10, and a frame body 25 (25-1 to 25-1 made of a mold resin is formed so as to surround the entire circumference of the key tops 20.
2) is formed by molding. The frame body 25 is separated at 12 places to form 12 frame body portions 25-1 to 25-12. Each component will be described below.

The film plate 10 is made of a flexible thermoplastic synthetic resin film, such as PETP (polyethylene terephthalate). In this embodiment, since the key top plate 1 itself has a waterproof structure, the film plate 10 is not provided with any through hole.

The key top 20 is filled with a thermoplastic molding resin 23 such as PMMA or PC (polycarbonate) to bend a predetermined position of the film plate 10 upward to provide a curved portion 21, and at the same time,
The filled mold resin 23 is fixed to the inside of the curved portion 21. A pressing portion 27 projects from the center of the lower surface of the molding resin 23.

Twelve frame body parts 25-1 constituting the frame body 25
25-12 are attached to the lower surface of the film plate 10 so as to be fixed to the film plate 10. A locking projection 26 is projected downward from each of the frame portions 25-1 to 25-12. Among the respective locking projections 26, the locking projections 26 provided on the two frame portions 25-2 and 25-5 are formed longer than the others.

Further, among the frame body portions 25-1 to 25-12, the frame body portions 25-2 and 25-12, 25-3 facing each other in the width direction are provided.
And 25-11, 25-4 and 25-10, 25-5 and 25
Each of -9, 25-6 and 25-8 is connected by a rod-shaped connecting portion 29. That is, each connecting portion 29
It is provided so as to partition each key top 20.

Next, a method for manufacturing the key top plate 1 will be described. That is, first, as shown in FIG. 2, a flat film plate 10 is prepared, and the frame portions 25-1 to 25-1 on the lower surface thereof are prepared.
2 and the adhesive 30 is printed on the portion where the connecting portion 29 is provided. The adhesive 30 is a hot melt type adhesive such as vinyl chloride resin or polyester resin, or urethane resin,
It consists of a thermosetting adhesive such as epoxy resin.

Next, as shown in FIG. 3A, the film plate 10 is sandwiched between the upper and lower molds A and B. At this time, the upper mold A is provided with six recesses a1 for molding the upper shape of each key top 20 shown in FIG.

On the other hand, in the lower die B, each frame body portion 2 shown in FIG.
There are provided a concave portion b1 for providing the 5-1 to 25-12 and the connecting portion 29, and a concave portion b2 for forming the pressing portion 27 of each key top 20 shown in FIG. 1, and each concave portion b.
Pin gates b5 and b6 are provided at 1 and b2, respectively.

Then, the high temperature from each pin gate b5, b6
When a thermoplastic molten mold resin such as PC or PMMA is press-fitted at a high pressure, the molten mold resin is filled in the recesses b1 and b2 of the lower mold B. And FIG. 3 (b)
As shown in FIG. 5, the portion of the film plate 10 located in the recess a1 is pushed up and deformed while being stretched by the heat and pressure of the molten mold resin, and is adhered to the inner surface of the recess a1 as indicated by the dotted line. The curved portion 21 is formed and at the same time, the molten mold resin is filled in the recesses a1 and b2. Further, as shown in FIG. 3C, the molten mold resin filled in the recess b1 comes into close contact with the lower surface of the film plate 10 on which the adhesive 30 is printed.

After cooling, the upper and lower molds A and B are removed to complete the key top plate 1 shown in FIG. At this time,
The mold resin 23 and the surface of the curved portion 21 of the film plate 10 are firmly fused to each other, and at the same time, the frame portions 25-1 to 25-12 and the connecting portion 29 are firmly attached to the lower surface of the film plate 20 by the adhesive 30. Is glued to.

By the way, the inventor of the present invention, when the thermoplastic resin film is stretched in a high temperature and high pressure state and brought into contact with the high temperature and high pressure molten mold resin, the resin film and the mold resin do not use any adhesive. However, it was found from various experiments that the two were firmly fused together.

Therefore, as in the above embodiment, the film plate 1
When 0 is stretched at high temperature and high pressure to form the curved portion 21, and at the same time the high-temperature and high-pressure molten mold resin 23 is brought into contact with the film plate 10, both are firmly fused and fixed without an adhesive. Of.

On the other hand, the frame portions 25-1 and 25-2 of the film plate 10
Since the film plate 10 does not extend at the portion where the 5-12 and the connecting portion 29 are attached, it is difficult for the mold resin to be directly fused. Therefore, the adhesive 30 is printed in advance on this portion.

Depending on the material of the film plate 10, the material of the mold resin, the molding conditions such as heat and pressure of the mold resin, the mold resin may be directly fused to the film plate 10 without extending the film plate 10. In this case, the adhesive 30 of the above embodiment may be omitted. Also, an adhesive may be printed in advance on the lower surface of the curved portion 21 of the above-described embodiment.

In the present embodiment, as shown in FIG. 1, the frame 25 surrounding the six key tops 20 is set to one.
It separated into 2 frame parts 25-1 to 25-12. Therefore, the mold resin 23 that becomes the key top 20 is formed on the film plate 10.
When the frame parts 25-1 to 25-12 and the connecting part 29 are molded, high heat is applied, and when they cool, the amount of shrinkage of the two differs depending on the difference in the linear expansion coefficient of the two, but each frame Since the fixing length of the portions 25-1 to 25-12 to the film plate 10 is short, the key top plate 1 is not likely to warp.

Needless to say, the number of frames 25 to be separated can be variously changed depending on the linear expansion coefficient, size, shape, etc. of the film plate 10 and the frame 25.

By the way, in the above-described embodiment, the connecting portion 29 is provided between the key tops 20 so as to partition the key tops 20.
This is because the position of is always constant and the pressing operation is good.

Further, since the key top plate 1 shown in FIG. 1 can be easily bent at the portion where the frame body 25 is separated, even if the surface to which the key top plate 1 is attached is a curved surface, this can be easily accommodated. it can.

Next, FIG. 4 is an exploded perspective view showing one specific example of use of the key top plate 1. In the figure, 40 is a decorative plate, 45 is a switch substrate, and 60 is an adhesive holding plate.

Desired characters, patterns and colors are printed on the upper surface of the decorative plate 40, and the keytops 20 penetrate through the keytops 1 at positions facing the keytops 20. A through hole 41 is provided.

The switch substrate 45 has a contact pattern formed on one surface of a flexible film plate 47, and is folded with the surface provided with the contact pattern inside so that the contact patterns face each other. A switch contact is configured, and a metal dome-shaped click plate 49 is attached by an adhesive tape 51 on a portion to be the switch contact. Reference numeral 53 is a through hole that penetrates each locking projection 26 provided on the key top plate 1.

The adhesive holding plate 60 is a so-called double-sided tape plate in which an adhesive layer is provided on the upper and lower sides of a resin or paper plate. In the figure, the upper adhesive layer is exposed and the lower adhesive layer is exposed. A protective sheet 63 is attached.

Then, the key top plate 1 to which the decorative plate 40 is attached is placed on the switch substrate 45, and the respective locking projections 26 of the key top plate 1 penetrate through the through holes 53 of the switch substrate 45 and the shorter one on the lower surface thereof. The tips of the locking projections 26 are heat-squeezed to fix the two.

Next, the adhesive holding plate 60 is adhered to the lower surface of the switch substrate 45. At this time, the longer locking projection 26 of the key top plate 1 projects below it through the notch 61 provided on the side surface of the adhesive holding plate 60. This longer locking projection 2
6 is used for positioning when the protective sheet 63 on the lower surface of the adhesive holding plate 60 is peeled off and the adhesive layer is adhered to another member. Further, if the tip is caulked, the fixing is surely done.

Next, FIGS. 5A to 5C are key top plates 65, 69, 71 according to other embodiments of the present invention.
FIG. The same parts as those of the key top plate 1 shown in FIG. 1 are designated by the same reference numerals.

The key top plate 65 shown in FIG. 7A and the key top plate 69 shown in FIG. 7B are different from the key top plate 1 shown in FIG. 29 is not provided at all, and in the case of the key top plate 69, the connecting portion 29 is provided for every two key tops 20. As long as the tension of the film plate 10 can be maintained, it may be configured as described above.

On the other hand, in the case of the key top plate 71 shown in FIG. 7C, the frame portions 25-1 to 25-12 and the connecting portion 29 are not only provided on the back side of the film plate 10 but also on the front side thereof. That is the point.

The upper frame parts 25'-1 to 25'-12 and the connecting part 29 'may be adhered to the film plate 10,
A through hole (not shown) may be provided in the film plate 10 so as to be integrally formed with the lower frame body parts 25-1 to 25-12 and the connecting part 29. At this time, the connecting portions 29 and 29 'may be omitted, as in the case of FIGS. 5 (a) and 5 (b).

Further, the structure of the key top is not limited to the above-mentioned respective embodiments, and for example, as shown in the conventional example of FIG. 6, a hole is formed in the film plate and the molding resin is formed above and below the film plate so as to penetrate the hole. Various modifications are possible such that the key top may be formed by integrally molding.

[0043]

As described above in detail, according to the key top plate of the push button switch of the present invention, when the frame body is molded on the film plate, the film plate is not warped at all. Have the effect.

[Brief description of drawings]

1A and 1B are views showing a structure of a key top plate 1 according to an embodiment of the present invention, in which FIG. 1A is a front perspective view, FIG. 1B is a rear perspective view, and FIG. (C) is a side view and (d) is a sectional view taken along the line AA of (a).

FIG. 2 is a diagram for explaining a method of manufacturing the key top plate 1.

FIG. 3 is a diagram for explaining a manufacturing method of the key top plate 1.

FIG. 4 is an exploded perspective view showing one specific usage example of the key top plate 1.

5 (a), 5 (b) and 5 (c) are perspective views showing key top plates 65, 69 and 71 according to other embodiments of the present invention.

6A and 6B are views showing a conventional key top plate 80. FIG. 6A is a plan view, FIG. 6B is a sectional view taken along the line aa in FIG. 6A, and FIG. 6C is a film. It is a top view of the board 81.

[Explanation of symbols]

 1 key top board 10 film board 20 key top 25 frame body 25-1 to 25-12 frame body part

Claims (1)

[Claims] 1. A push-button switch in which a molding resin is molded on a film plate made of a flexible resin film to form a key top, and a frame made of a molding resin is molded so as to surround the key top. The key top plate of the push button switch, wherein the frame is separated at a plurality of locations.