Illumination key and method of manufacture thereof

Abstract: The present invention provides an illumination key and a method of making such illumination key, in which the upper surface of the key top is curved and slanted at an angle to make it possible to reliably recognize the pattern (such as a letter or the like) printed thereon, the key operating portion is provided with a rubber-like click sensitivity and elasticity while the keytop portion is made of a hard resin, with the key operating portion and the keytop being reliably bonded to each other, and in which a pattern such as a letter or the like can be simply created without the need for laser etching, and wherein it is possible to reliably carry out ON/OFF operations of a one keytop without operating neighboring keytops.

Description: The present invention relates to an illumination key for use in various mobile communication devices, such as cellular phones and automobile phones, and various terminal devices, such as electronic organizers and the like, to enable the keys thereof to be visible in nighttime and low light conditions. In particular, the present invention relates to an illumination key of the type defined in the precharacterizing portion of claim 1. The present invention further relates to a method of manufacturing such illumination key. Description of the Prior Art In the prior art, this type of illumination key, such as disclosed in EP-A-0 593 804; is constructed by forming a printed pattern layer, such as a character or the like, into the underside surface of a key top made of light-permeable resin and then fixing a silicon rubber key operating portion to the back side of the printed pattern layer by means of silicon rubber and an adhesive having good adhesive properties. Further, in the case where a printed pattern layer, such as a character or the like, is formed in the surface of the key top, the etching of the character is carried out with a laser beam, and this makes such prior art illumination keys expensive to manufacture. Moreover, because the printed pattern (character) layer is formed in the underside surface of the light-permeable resin key top, the printed pattern (character) is difficult to see in the illumination key described above in the case where the upper surface of the key top has a curved shape. Furthermore, because the printed pattern (character) is etched by means of a laser beam, it is not possible to prevent high costs when manufacturing such illumination keys. Moreover, in the case where a printed pattern (characters) is formed on one side of a film which is placed over a plurality of light -permeable resin key tops and heat fused to the upper and side surfaces thereof, because the key tops are connected to each other via the film, misoperations can occur when the operation of one key top also operates a neighboring key top. SUMMARY OF THE INVENTION With a view towards overcoming the problems of the prior art discussed above, it is an object of the present invention to provide an illumination key which makes it possible to reliably recognize a printed pattern (character) even when the upper surface of the key top is slanted or curved, in which a key operating portion is given a rubber-like click sensitivity and a rubber-like elasticity, the key top portion is made from a rigid resin, and a reliably strong bond is created between the key operating portion and the key top. It is a further object of the present invention to provide an illumination key and a method of manufacturing such illumination key which makes it possible to easily manufacture a printed pattern without laser etching and which makes it possible to reliably carry out ON/OFF operations for one illumination key without affecting (operating) any of the neighboring keys, in which a key operating portion is given a rubber-like click sensitivity and a rubber-like elasticity, the key top portion is made from a rigid resin, and a reliably strong bond is created between the key operating portion and the key top. In order to achieve these objects, the illumination key according to the present invention comprises the features of the characterizing portion of claim 1. In this structure, the film has a thickness of 100µm-200 µm, with the printed pattern being provided on either the top or bottom surface of the film. Although the key top is covered with the film, key tops are not connected with each other via the film. Accordingly, misoperations will not occur such as the operation of one key top also operates a neighboring key top. Further, the method of manufacturing the illumination key according to the present invention, comprises the steps of claim 3. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional schematic view of one embodiment of the present invention. Fig. 2 is a cross-sectional schematic view of another embodiment of the present invention. Fig. 3(a) - (g) are explanatory schematic views showing the process of the method of manufacturing the illumination key according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description of a preferred embodiment of the present invention will now be given below. As shown in the drawings, a light-permeable key pad 1 has an operating portion la and a non-operating portion 1b connected to the operating portion la formed as an integral body from transparent silicon rubber, other transparent rubber or transparent thermoplastic elastomer such as vinyl chloride based elastomer, polyolefin base elastomer, polysterene-polybutadiene copolymer thermoplastic elastomer, ethylene vinyl acetate elastomer, chlorinated polyethylene elastomer, polyurethane rubber or the like. By forming the keypad 1 from rubber or a thermoplastic elastomer, it is possible to utilize the rubber-like characteristics to obtain click-sensitivity and rapid operation sensitivity with the operating portion la. Further, in addition to the case shown in Fig. 1, in which the operating portion la is formed from a thin skirt portion 1c, which rises up along a slant from the lower portion of the side surface of the non-operating portion 1b, and a key top support portion 1d which is integrally supported at the upper portion of the skirt portion 1c, it is possible to construct the operating portion la as shown in Fig. 2, in which forms the erect thin skirt portion 1c toward the upper slanting portion thereof, or, the slanting skirt portion is eliminated and the key top supporting portion extends out horizontally from a thick side surface of the non-operating portion 1b. In this connection, it should be noted that the present inventionis not limited to these structures, and it is possible to utilize anyother structure so long as it is possible to support a key top 2. In the case where a skirt portion 1c is provided, this skirt portion 1c carries out a click action. Further, the operating portion 1a is arranged above a substrate (not shown in the drawings) at a position corresponding to a fixed contact point on the substrate, with a rubber click structure being created by forming an electrically conductive contact member on the underside of the operating portion 1a, or with a dome click structure being created by means of a dome switch such as a metal dome switch (not shown in the drawings). The key top 2, made from a thermoplastic resin such as ABS, polycarbonate, acrylic resin or the like, is fixedly mounted to the top of the key top support portion 1d by means of a transparent adhesive 3. In this connection, the upper surface of the key top 2 may have any of a variety of shapes, such as a curved shape which slants in one direction, for example. Further, the lower portion of the key top 2 may be formed to include a brim portion 2a, as shown in Fig. 3, or thelower portion of the key top 2 may be formed without such a brim portion. In general, to enable light to pass through the key top 2, a transparent or translucent material around 1mm thick (e.g., in the range 0.8mm - 1.5mm) is used to make the key top 2, and in this regard it is possible to use a white-colored material which allows light at a certain intensity to pass therethrough. In the case where the key top 2 is formed from such partially light -permeable white-colored material, there is no need to form the partial transmission light reflecting membrane 4a described below. The transparent adhesive 3 is an adhesive used to bond the key top 2, made of a thermoplastic resin such as ABS, polycarbonate, acrylic resin or the like, with the key pad 1, made of a silicon rubber or other rubber material or thermoplastic elastomer, which is an integral body formed from the operating portion la and the non-operating portion 1b. In this connection, the adhesive 3 may be any adhesive which makes it possible to bind two different materials together; for example, it is possible to use a silicon type transparent adhesive in the case of silicon rubber. One method of forming a printed pattern (character) layer 4 on a surface of the resin key top 2 which excludes the underside there of is shown in Figs. 3 (a) - (g). In this method, a 100µm- 200µm thick film 6 made of a transparent synthetic resin such as polycarbonate or the like and having a printed pattern (character) preformed in one side thereof is set inside a metal resin forming mold 7, and then injection molding is carried out by injecting a resin into the cavity to form the key top 2, whereby the film 6 formed with the printed pattern layer 4 is heat fused to the surface of the key top 2. In this connection, it is to be noted that the printed pattern surface may be formed on either the upper or lower surface of the film 6. In the case where the printed pattern surface is formed on the upper surface of the film 6, a protection layer 5 formed, for example, from a clear urethane coating is provided on top of the printed pattern surface. Further, it is necessary to set the thickness of the film 6 at 100 µm- 200µm to give the film 6 sufficient strength when undergoing operations inside the metal mold 7. Next, a jig 8 is used to cut away the film 6 from the lower periphery of the key top 2. In this way, by using the jig 8 to cut away the film 6 from the lower periphery of the key top 2, when one key top 2 is pressed, such action does not operate neighboring key tops, and this makes it possible to reliably carry out ON/OFF operations for a particular key top 2. Next, the underside surface of the key top 2 is fixed by means of a transparent adhesive 3 to the upper surface of a key operating portion la made from a light-permeable silicon rubber. Now, by having the structure described above, the illumination key according to the present invention makes it possible to reliable recognize the character (pattern) on the key top 2 even when the upper surface of the key top 2 has a curved or slanting shape. Furthermore, because the key operating portion creates a rubber-like click sensitivity and a rubber-like elasticity while the resin of the key top portion is made rigid, and because it is possible to reliably achieve a strong bond between the key operating portion and the key top, the illumination key according to the present invention makes it possible to reliably carry out key operations by preventing misoperations and other problems such as peeling or the like. Furthermore, in the method of manufacturing an illumination key according to the present invention, the use of a laser is done away with and the printed pattern (character) layer is easily formed using printing technology. Moreover, because the film of one key top is separate from the film of the other key tops, the operation of one key top does not affect (operate) any of the neighboring key tops, and this makes it possible to reliably carry out ON/OFF operations for any key top.

Claims: An illumination key, comprising: a light-permeable resin key top (2); and an upper surface of a key operating portion (1a) made from transparent rubber or thermoplastic elastomer, being fixed to the underside surface of the key top (2) by means of a transparent adhesive (3); the key being characterized by a film (6) having a pattern formed in the upper or the bottom surface of the film (6), the film (6) being fixed to the upper and side surfaces of the transparent resin key top (2), and portions of the film (6) that extend beyond the lower periphery of the key top (2) being cut away. The illumination key of claim 1, wherein the film (6) has a thickness of 100 µm - 200 µm. A method of manufacturing an illumination key, comprising the steps of: setting a film (6) having a pattern formed in one side thereof inside a mold (7); injecting a light-permeable resin material into the mold (7) to form a key top (2); fixing the film having a pattern to the upper and the side surfaces of the transparent key top resin; cutting away portions of the film (6) that extend beyond the lower periphery of the key top (2) using a jig (8); and fixing the upper surface of the key operating portion (1a) made from a transparent rubber or thermoplastic elastomer to the underside surface of the key top (2) by means of a transparent adhesive (3).

Inventors: KENMOCHI YOSHIO, KENMOCHI, YOSHIO
Applicants: SUNARROW CO LTD, SUNARROW CO., LTD.
Application year: 1998
Main classification: H01H13
IPC codes: H01H13, B29C45, H01H9, H01H11, B29L31