Electricity: circuit makers and breakers – Solid contact – Membrane type
Reexamination Certificate
2002-07-12
2004-07-13
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Membrane type
C200S341000
Reexamination Certificate
active
06762381
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a key top used as a pushbutton switch for various mobile communication devices such as a mobile phone and an automobile telephone, a remote control, or car-mounted electronic equipment.
2. Description of the Related Art
As a material for a key top for a pushbutton switch of various mobile communication devices and electronic equipment, such as a mobile phone and a remote control, resins are mainly used for reasons such as a satisfactory sensation of an operation and rich design variations. In terms of enhancement of design, there is a demand for a sensation of a metal-type material with lustrousness of metal (in the present specification, referred to as a “sensation of metal”) and illumination of a display portion displaying a letter, a symbol, or the like.
In order to satisfy the above-mentioned demand, in the case of providing a sensation of metal to a key top by utilizing a resin material, a key top made of a resin is produced by a following method in which a metal layer is formed in a desired position of the surface of a key top made of a resin by vapor deposition or sputtering (first prior art) or a method in which a resin to be plated with metal and a resin that is not to be plated with metal are subjected to coinjection molding, whereby a plating layer is provided on the resin to be plated with metal (second prior art).
Alternatively, a key top made of a resin has also been produced by a method in which a coating with a sensation of metal is applied (third prior art) or a method in which an electroplating layer formed on the surface of a resin to be plated with metal is etched with a laser to form a letter, a symbol, or the like (fourth prior art).
However, according to the method of the first prior art, the metal layer formed by vapor deposition or sputtering is thin. Therefore, when a key top made of a resin is repeatedly pressed down, the metal layer wears away and may eventually disappear. In order to solve this problem, the surface of the metal layer is coated with a protective layer, the metal layer is formed on the reverse surface of a flat resin film, and the resultant film is curved along the surface of a key top made of a resin to be integrated with a key top body, and the like. According to the former method, dust is likely to adhere during coating. According to the latter method, the metal layer is likely to be cracked when the resin film is curved. In both methods, the yield is poor and the cost is high.
According to the method of the second prior art, the display portion is designed by coinjection molding. Therefore, a display portion with minute and complicated designs cannot be realized and the cost is high.
According to the method of the third prior art, compared with the case where the metal layer is formed by plating, it is difficult to provide a smooth mirror surface, and wear resistance is not satisfactory. According to the method of the fourth prior art, unless a laser treatment is conducted after plating, it is difficult to form, in particular, letters containing an island portion isolated from the periphery, such as digits “9” and “0”, and it is difficult to adjust a laser output for forming a display portion without influencing regions on the periphery of a letter, a symbol, or the like.
Jp 2000-207985 A describes a method of producing a key top by coating a desired site with a conductive ink, and plating the site coated with the conductive ink. However, according to this method, in order to decrease a resistance of the conductive ink, it is required to use silver powder or copper powder, which makes the conductive ink expensive, resulting in a high cost.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is an object of the present invention to provide a key top for a pushbutton switch having a sensation of metal, a rich design, a satisfactory yield, a low cost, the capability of being illuminated, and excellent durability.
In order to achieve the above-mentioned object, according to the present invention, a key top for a pushbutton switch in which a base layer made of an insulating resin that can be plated with metal and an electroless plating layer formed on the surface of the base layer are stacked on a key top body is provided.
In the key top for a pushbutton switch, the base layer made of an insulating resin that can be plated with metal is formed on a surface of the key top body, and the electroless plating layer is formed on a surface of the base layer. Therefore, the plating layer can be provided directly and easily on the insulating resin. As a result, a key top for a pushbutton switch can be obtained, which has a sensation of metal while using a resinous key top body, rich design, a satisfactory yield, and a low cost.
Furthermore, according to the present invention, there is provided a key top for a pushbutton switch in which a polymer coating layer is formed on the surface of the base layer, wherein the electroless plating layer is formed on the surface of the base layer where the polymer coating layer is not formed.
The electroless plating layer is formed on the surface of the base layer where the polymer coating layer is not formed. Therefore, a display portion, a pattern, and the like can be formed by the electroless plating layer and the polymer coating layer. As a result, a key top for a pushbutton switch having an improved design can be obtained. Furthermore, the periphery of the electroless plating layer is in contact with the polymer coating layer, so that the ends of the electroless plating layer can be protected by the polymer coating layer, and wear and a loss of the electroless plating layer can be prevented. Furthermore, during production, the polymer coating layer functions as a masking layer for a region where the electroless plating layer is not formed, so that the electroless plating layer can be easily attached to a desired place. As a result, a key top for a pushbutton switch that has the capability of being mass-produced at a low cost can be obtained.
Furthermore, according to the present invention, a key top for a pushbutton switch having an electroplating layer further formed by electroplating on the electroless plating layer is provided.
When the electroplating layer further formed by electroplating is provided on the electroless plating layer, a key top for a pushbutton switch can be obtained, which has enhanced wear resistance, lustrousness, and a sensation of metal.
Furthermore, according to the present invention, a key top for a pushbutton switch in which a polymer coating layer is further provided on the surface of the electroless plating layer or the electroplating layer is provided.
When the polymer coating layer is further provided on the surface of the electroless plating layer or the electroplating layer, these plating layers are protected by the polymer coating layer. Thus, wear and a loss of the plating layer can be prevented, and as a result, a key top for a pushbutton switch having enhanced wear resistance can be obtained. More specifically, even if the key top is pressed down repeatedly, the plating layer is unlikely to peel off. Furthermore, coloring that is not present on the key top body can be provided to the surface of the key top. For example, if the polymer coating layer is formed as a colored transparent layer, light reflected from the plating layer comes in the eyes of a human through the colored transparent polymer coating. Therefore, the key top surface having coloring that cannot be obtained only with the plating layer can be formed, which enables the design to be richer. In particular, even if a part of the plating layer forms a display portion of a letter, a symbol, or the like, the letter, the symbol, or the like does not peel off. Thus, a key top surface having enhanced durability with an enhanced design can be obtained.
According to the present invention, there is provided a key top for a pushbutton switch in which the polymer coating layer and the plating layer are formed so a
Hikita Atsushi
Kunthady Tedi
Enad Elvin
Fish & Neave
Fishman M.
Jackson Robert R.
Poh Philip R.
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