JPH09231856A - Key dome sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a key dome sheet capable of sufficiently reflecting light even when light from a light source is weak, and brightly illuminating a push key. SOLUTION: A key dome sheet 15 is formed by stacking a second supporting film 4 on the lower surface of a first supporting film 8, and sticking a metal mold dome 1 to the lower surface of the second supporting film 4. The first supporting film 8 is formed by forming a metal thin layer 6 on the lower surface of a transparent first base layer 7 by vapor deposition or others, then stacking a first sticky layer 5 on the lower surface of the metal thin film layer 6. The first supporting film 8 is three layer structure formed by stacking the metal thin film layer 6 between the first base layer 7 and the first sticky layer 5. The second supporting film 4 is two layer structure of a second base layer 3 and a second sticky layer 2 stacked on the lower surface of the second base layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key dome sheet for a switch device that requires key illumination, and more particularly to a key dome sheet suitable for illuminating push buttons of mobile phones.

[0002]

2. Description of the Related Art FIG. 4 is an exploded view showing a switch substrate using a conventional key dome sheet. (A) is a top view of a switch base substrate, (b) is a top view of a key dome sheet, c) is a top view showing an illumination switch board in which a key dome sheet is attached to the top surface of a switch base board,
FIG. 5 is a part of the cross-sectional view taken along the line AA of FIG. As shown in FIG. 4A, a plurality of switch terminals 13 are arranged at predetermined positions on the base substrate 10, and the switch terminals 13 are circular inward terminals 11 and
An annular outer contact terminal 12 having an inner diameter slightly larger than the diameter of the inner contact terminal 11 and arranged so as to surround the inner contact terminal 11.
It is composed of In addition, between the switch terminals 13 on the base substrate 10, each switch terminal 13
The plurality of light sources 9 so that the distances to
Is arranged. The internal terminal 11 and the external terminal 12
And an external connection terminal (not shown) of the light source 9 extends to the back surface of the base substrate 10 and is electrically connected to a circuit and a power supply of an electric device on which the base substrate 10 is mounted.

The key dome sheet 20 shown in FIG. 4 (b) has a supporting film 23 whose lower surface is an adhesive surface, and is formed into a dome shape as shown in FIG. 1 is adhesively fixed to the adhesive surface at its outer surface. These metal forming domes 1 are shown in FIG.
Switch terminal 1 on base substrate 10 shown in FIG.
It is arranged at a position corresponding to the position of the arrangement pattern of No. 3. In addition, the metal molding dome 1 in the support film 23
For a light source in which the light source 9 disposed on the base substrate 10 can be inserted when the key dome sheet 20 is attached on the base substrate 10 between the regions 21 (hereinafter referred to as “dome parts”) in which the is disposed. The opening 22 is formed.

The key dome sheet 2 having the above structure
0 is attached to the upper surface of the base substrate 10 shown in FIG. 4 (a) so that the metal molding dome 1 is located on the switch terminals 13 to obtain the illuminated switch substrate 30 shown in FIG. 4 (c). You can

FIG. 6 is an enlarged sectional view showing a part of the key dome sheet surrounded by the circle C shown in FIG. This figure 6
As shown in FIG. 2, the support film 23 is composed of a transparent base layer 33 made of, for example, PET, and an adhesive layer 32 laminated on the lower surface thereof, and the metal forming dome 1 is adhered and fixed to the adhesive layer 32. There is. Further, as shown in FIG. 5, the lower end edge portion 1 a of the metal forming dome 1 is the outer contact terminal 1
2 is in contact with the upper surface. Further, the light source 9 is arranged on the base substrate 10 so as to pass through the light source opening 22 provided in the key dome sheet 20 and project upward.
Generally, the thickness of the base layer 33 is about 50 μm in consideration of the flexibility of the key dome sheet 20, and the adhesive layer 3
The thickness of 2 is about 20 to 30 μm.

In the switch substrate 30 having the above structure, the specific dome portion 21 of the key dome sheet 20 is pushed down from above. Then, the metal-molded dome 1 is dented, so that the inner top of the metal-molded dome 1 comes into contact with the inner contact terminal 11 and the outer contact terminal 12 and the inner contact terminal 1
And 1 are electrically connected. This enables the switch terminal 1
3 can function as a switch.

When such a switch substrate 30 is used as a switch substrate such as a push button of a mobile phone, an area above the switch substrate 30 is a cover (excluding an area directly above each dome portion 21). (Not shown). In addition, a transparent push key (not shown) is arranged in a region directly above each dome portion 21 on the same plane as this cover so as to be in contact with the top of the dome portion 21.
It should be noted that numbers or the like are written on the push keys or on the top of the dome portion 21.

When the light source 9 on the switch substrate 30 is turned on, the light from the light source 9 is reflected by the dome portion 21 to illuminate the push key arranged immediately above. As a result, even when the mobile phone is used in the dark, the user can easily recognize the number written on the push key or the like.

In the switch substrate 30 that illuminates the push key as described above, the light from the light source 9 is emitted from the key dome sheet 2.
In order to efficiently reflect the light from the dome portion 21 of 0,
As the support film 23, one having an adhesive layer 32 colored in white is used.

[0010]

However, in the mobile phone having the switch substrate 30 in which the supporting film 23 having the white adhesive layer 32 as described above is used,
When the light from the light source 9 is weak, the light reflected by the dome portion 21 of the key dome sheet 20 to irradiate the push key also becomes weak, so that it may not be possible to recognize numbers such as the push key in the dark. .

The present invention has been made in view of the above problems. Even when the light from the light source is weak, the light can be sufficiently reflected and the push key can be illuminated brightly. An object is to provide a key dome sheet that can be used.

[0012]

A key dome sheet according to claim 1 of the present application comprises a first support film having a metal thin film layer capable of specular reflection, and a second support film laminated on the first support film. It is characterized by having a plurality of metal forming domes adhered and fixed to the second supporting film. In addition, the first support film has the metal thin film layer laminated between a transparent first base layer and a first adhesive layer.
The second support film preferably has a layered structure, and the second support film preferably has a two-layered structure in which a second base layer and a second adhesive layer are laminated.

The key dome sheet according to claim 4 of the present application is
A base layer, an adhesive layer laminated on one surface of the base layer, a specularly reflective metal thin film layer laminated on the other surface of the base layer, and a transparent resin layer laminated on the metal thin film layer. It is characterized by having a support film having a four-layer structure and a plurality of metal-molded domes that are adhesively fixed to the adhesive layer.

In the key dome sheet according to claim 1 of the present application, since the first supporting film has the metal thin film layer capable of specular reflection, the light from the light source can be reflected with high reflectance. Further, since the second support film is laminated between the first support film and the metal forming dome, the second support film is damaged even if the switch operation for pushing down the metal forming dome is repeated. Therefore, it is possible to prevent the metal thin film layer and the metal forming dome from coming into contact with each other to be electrically connected. Therefore, it is possible to prevent the metal-molded dome from being electrically connected to another metal-molded dome through the metal thin film layer, and to secure the independence of the switch for each metal-molded dome. You can

In the key dome sheet according to claim 2 of the present application, the first supporting film has a three-layer structure in which the metal thin film layer is laminated between a transparent first base layer and a first adhesive layer. Thereby, the light from the light source can be reflected with a higher reflectance. In addition, by adhering the first adhesive layer to the second support film, the first support film and the second support film can be easily laminated.

In the key dome sheet according to claim 3 of the present application, the second supporting film has a two-layer structure in which the second base layer and the second adhesive layer are laminated, so that the switch operation is repeated. The second support film is less likely to be damaged and the metal forming dome can be easily attached to the second support film.
It can be adhesively fixed to the adhesive layer.

In the key dome sheet according to claim 4 of the present application, the support film has a four-layer structure including a base layer, an adhesive layer, a metal thin film layer and a transparent resin layer. In this support film, since the metal thin film layer capable of specular reflection is laminated on the base layer, the light from the light source can be reflected with high reflectance. Further, since the transparent resin layer is laminated on the metal thin film layer, it is possible to prevent the metal thin film layer from being damaged even when the switch operation is repeated. Furthermore, since the base layer is laminated between the metal thin film layer and the metal forming dome, the base layer is damaged and the metal thin film layer and the metal forming dome are separated even if the switch operation of pushing down the metal forming dome is repeated. It does not come into contact and become conductive. Furthermore, since the adhesive layer is laminated on the base layer, the metal-molded dome can be easily adhered and fixed to the support film.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be specifically described with reference to the accompanying drawings. FIG. 1 is a sectional view showing an illumination switch board using a key dome sheet according to an embodiment (first embodiment) of the invention according to claim 1 of the present application. In FIG. 1, components having the same functions as those in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, a plurality of switch terminals 13 consisting of an internal contact terminal 11 and an external contact terminal 12 are arranged on the base substrate 10, and between the switch terminals 13 on the base substrate 10. A plurality of light sources 9 are arranged in the area of so as to project upward. A key dome sheet 15 having a plurality of metal molding domes 1 is attached to the upper surface of the base substrate 10.
In this key dome sheet 15, the metal forming dome 1
Is adhered and fixed to the lower surface of the second support film 4, and is in contact with the circumscribing terminal 12 at the lower end edge portion 1a thereof. Also,
The first support film 8 is laminated on the upper surface of the second support film 4. Further, the key dome sheet 15 has a light source opening 22 through which the light source 9 can be inserted.

FIG. 2 is an enlarged sectional view showing a part of the key dome sheet 15 surrounded by the circle C shown in FIG. As shown in FIG. 2, in the key dome sheet 15, the second support film 4 is laminated on the lower surface of the first support film 8,
The metal molding dome 1 is configured to be adhesively fixed to the lower surface of the second support film. The first support film 8 has a metal thin film layer 6 made of, for example, an aluminum alloy laminated on the lower surface of the transparent first base layer 7 by vapor deposition or the like, and the first adhesive layer 5 is laminated on the lower surface of the metal thin film layer 6. Has been done. That is, the first support film 8 has a three-layer structure in which the metal thin film layer 6 is laminated between the first base layer 7 and the first adhesive layer 5. On the other hand, the second support film 4 is the second base layer 3
And a second adhesive layer 2 laminated on the lower surface of the second base layer 3 has a two-layer structure.

The first support film 8 and the second support film 4 configured as described above are used to bond the lower surface of the first adhesive layer 5 and the upper surface of the second base layer 3 to each other, so that the key dome sheet 15 The support film is formed, and the key dome sheet 15 is formed by adhesively fixing the metal forming dome 1 to the lower surface of the second adhesive layer 2. In addition,
Since the first base layer 7 and the second base layer 3 are both thin film layers having a thickness of, for example, 25 μm, the flexibility of the key dome sheet 15 due to the lamination of the first base layer 7 and the second base layer 3 can be improved. The decrease can be suppressed.

When the switch substrate having such a key dome sheet 15 is used as a switch substrate for a push button of a mobile phone, the light from the light source 9 is specularly reflected on the metal thin film layer 6 of the first supporting film 8. Therefore, it is possible to irradiate a push key (not shown) arranged directly above the dome portion 21 of the key dome sheet 15 with high reflectance as compared with the conventional white support film. As a result, the push key can be brightened, and even when the light of the light source 9 is weak when the mobile phone is used in the dark, the number or the like of the push key can be easily recognized. The second base layer 3 is not necessarily transparent, but the first base layer 7 is transparent in order to irradiate the push key with the intensity as it is by the light reflected by the metal thin film layer 6. Is preferred.

In the support film of the key dome sheet 15, the second base layer 3 of the second support film 4 is laminated between the metal thin film layer 6 of the first support film 8 and the metal forming dome 1. The second base layer 3 is less likely to be damaged even if the switch operation of pushing down the metal forming dome 1 is repeated, and it is possible to prevent the metal forming dome 1 and the metal thin film layer 6 from being electrically connected.

Next, an embodiment (second embodiment) of the invention according to claim 4 of the present application will be described. FIG. 3 is an enlarged sectional view showing a part of the key dome sheet according to the second embodiment of the present invention. This key dome sheet is constructed by adhering and fixing the metal molding dome 1 to the lower surface of the supporting film 19, and the supporting film 19 is formed on the upper surface of the base layer 17 having the adhesive layer 16 on the lower surface by vapor deposition or the like, for example, aluminum alloy. A metal thin film layer 6 composed of
It has a four-layer structure in which a transparent resin layer 18 is laminated on the upper surface of the metal thin film layer 6.

In the switch substrate using the key dome sheet having the supporting film 19 thus constructed, the light from the light source 9 is specularly reflected by the metal thin film layer 6 as in the first embodiment. Therefore, the push key can be irradiated with high reflectance as compared with the conventional white support film.

Further, as shown in FIG. 3, since the resin layer 18 is laminated on the upper surface of the metal thin film layer 6 and the base layer 17 is laminated between the metal thin film layer 6 and the metal forming dome 1, Even if the switch operation is repeated, the metal thin film layer 6 can be prevented from being damaged, and the metal molding dome 1 and the metal thin film layer 6 can be prevented from becoming electrically conductive.

[0027]

As described above, according to the first aspect of the present invention, in the supporting film of the key dome sheet having the first and second supporting films, the first supporting film is a metal thin film layer capable of specular reflection. Therefore, the light from the light source can be reflected with a high reflectance as compared with the conventional white support film, and the push key or the like arranged above the metal forming dome can be illuminated more brightly. For this reason, when such a key dome sheet is used for a switch substrate such as a push button of a mobile phone, even if the light from the light source is weak when the mobile phone is used in the dark, the numbers of the push keys can be easily displayed. Can be recognized. Further, even when the switch operation of pushing down the metal forming dome is repeatedly performed, the second supporting film is less likely to be damaged, and the metal thin film layer and the metal forming dome come into contact with each other and become conductive. Can be prevented.

According to the second aspect of the present invention, by making the first base layer of the first support film transparent, it is possible to reflect the light from the light source with higher reflectance.

According to claim 3 of the present application, the second support film has a two-layer structure of a second base layer and a second adhesive layer, so that the second support film can be used even if the switch operation is repeated.
The support film can be prevented from being damaged, and the metal forming dome can be easily adhered and fixed to the second adhesive layer.

According to claim 4 of the present application, since the support film is formed by laminating the metal thin film layer capable of specular reflection on the base layer, the light from the light source is higher than that of the conventional white support film. It can be reflected with a reflectance, and a push key or the like arranged above the metal forming dome can be illuminated more brightly. Further, since the transparent resin layer is laminated on the metal thin film layer, it is possible to prevent the metal thin film layer from being damaged even when the switch operation is repeated.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of an illumination switch board using a key dome sheet according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a portion surrounded by a circle C in the key dome sheet shown in FIG.

FIG. 3 is a cross-sectional view showing an enlarged part of a key dome sheet according to a second embodiment of the present invention.

FIG. 4 is an exploded view showing an illumination switch substrate using a conventional key dome sheet, (a) is a top view of a switch base substrate, (b) is a top view of a key dome sheet,
(C) is a top view showing a switch substrate in which a key dome sheet is attached to the upper surface of a switch base substrate.

5 is a part of a cross-sectional view taken along the line AA of the switch substrate of FIG. 4 (c).

6 is an enlarged sectional view showing a portion surrounded by a circle C in the key dome sheet shown in FIG.

[Explanation of symbols]

 1; Metal forming dome 1a; Edge portion 2; Second adhesive layer 3; Second base layer 4; Second support film 5; First adhesive layer 6; Metal thin film layer 7; First base layer 8; First support film 9; Light source 10; Base substrate 11; Inner contact terminal 12; Outer contact terminal 13; Switch terminal 15, 20; Key dome sheet 16, 32; Adhesive layer 17, 33; Base layer 18; Transparent resin layer 19, 23; Support film 21: Dome part 22: Light source opening 30: Switch substrate

Claims (4)

[Claims] 1. A first device having a mirror-reflectable metal thin film layer.
A key dome sheet comprising a support film, a second support film laminated on the first support film, and a plurality of metal-molded domes adhered and fixed to the second support film. 2. The first support film has a three-layer structure in which the metal thin film layer is laminated between a transparent first base layer and a first adhesive layer, and the first support film has a three-layer structure. Key dome sheet. 3. The key dome sheet according to claim 1, wherein the second support film has a two-layer structure in which a second base layer and a second adhesive layer are laminated. 4. A base layer, an adhesive layer laminated on one surface of the base layer, a specularly reflective metal thin film layer laminated on the other surface of the base layer, and a metal thin film layer laminated on the metal thin film layer. A key dome sheet comprising a support film having a four-layer structure of a transparent resin layer and a plurality of metal-molded domes that are adhesively fixed to the adhesive layer.