Abstract: A method of strongly affixing a molding resin to a synthetic resin film in direct fashion includes preparing a synthetic resin film and a molding resin each of which consists of a thermoplastic material, stretching a prescribed surface of the synthetic resin film, simultaneously bringing the molten, high-temperature molding resin into contact with the surface of the synthetic resin film, while stretching of the surface thereof is in progress, in such a manner that the molding resin presses directly against this surface in a state of high pressure, and subsequently cooling a surface of contact between the synthetic resin film and molding resin to a temperature at which the molten molding resin solidifies. As a result, the surfaces of contact between the synthetic resin film and molding resin are directly and strongly fused.

Abstract: A keytop plate comprises keytops (21) formed by integrally molding a molding resin part (25) with a synthetic resin film (23), and a molded elastomer sheet (molded elastomer member) (11) attached to the keytops (21). The molded elastomer sheet (11), other than in the areas to which the keytops (21) are attached, has no through-holes, whereby a water-proof property is provided. The keytops (21) are easily depressed even when the molded elastomer sheet (11) is securely held at its peripheral portion. A hard tactile feeling may be obtained when the keytops (21) are depressed, since the keytops (21) are formed from the synthetic resin film (23) and the molding resin part (25).

Abstract: A keytop sheet of a push-button switch includes a keytop made of synthetic resin that is molded on a sheet of resin film. A portion of the film sheet surrounding the portion thereof on which the keytop is molded is provided with a curved projection protruding in a downward and/or upward direction from the surface of the film sheet. Such curved projection can be replaced by providing the portion of the film sheet surrounding the portion thereof on which the keytop is molded with a cut-out to form a hinge portion. A nameplate provided with a hole shaped so that the keytop may be passed therethrough is attached to the film sheet so as to cover the cut-out and hinge portion of the film sheet. The nameplate can have an outer diameter greater than that of the film sheet. A frame made of synthetic resin is fixed to an underside of the film sheet on an outer peripheral portion thereof. An outer peripheral portion of the nameplate is bent and fixed to an outer peripheral side surface of the frame.

Abstract: A method of enlarging a design possessed by a synthetic resin film includes a printing step of printing the design on the top side of the synthetic resin film, and an enlarging deformation step of providing a curved portion by stretching a prescribed surface of the synthetic resin film which includes a portion on which the design has been printed and curvingly deforming the prescribed surface in such a manner that the surface will protrude above the plane defined by the synthetic resin film. The design printed on the synthetic resin film beforehand in the printing step is printed in dimensions conforming to the rates of enlargement of points on the curved portion of the synthetic resin film. A portion of the design having a small rate of enlargement is printed at relatively large dimensions in comparison with other portions thereof and a portion of the design having a high rate of enlargement is printed at relatively small dimensions in comparison with other portions thereof.

Abstract: A keytop sheet of a push-button switch includes a keytop, which is made of synthetic resin, molded on a sheet of resin film. A portion of the film sheet surrounding the portion thereof on which the keytop is molded is provided with a curved projection protruding in a downward and/or upward direction from the surface of the film sheet. Alternatively, a cut-out separates the portion of the film sheet on which the keytop is molded from the remainder of the film sheet while leaving a hinge portion, and a nameplate through which the keytop passes is attached to the film sheet so as to over the cut-out and hinge portion of the film sheet. The nameplate may have an outer diameter greater than that of the film sheet, and a frame made of synthetic resin is fixed to an underside of the film sheet on an outer peripheral portion thereof. The outer peripheral portion of the nameplate is bent and fixed to an outer peripheral side surface of the frame.

Abstract: A push-button switch keytop includes a flexible resin film deformed in such a manner that the resin film bulges upwardly to form a curved portion that is filled with a molding resin while the resin film is being deformed. The molding resin is allowed to harden to form a keytop body, whereby the top side of the keytop body consisting of the molding resin is integrated with the resin film in a state in which the top side of the keytop body is covered by the resin film. The keytop is manufactured by clamping a resin film between upper and lower molds, charging a molten resin from a pin gate provided on the lower mold into a cavity provided in the lower mold, thereby deforming and urging the resin film upward by pressure and heat produced by the molten resin and causing the resin film to adhere to the inner surface of the upper mold, filling the cavities of the upper and lower molds with the molten resin and separating the upper and lower molds after the resin hardens.

Abstract: A molded resin casing of an electronic part equipped with a flexible flat cable and internally accommodating a board on which are formed electric conductor patterns slidingly contacted by contacts of a slider of the electronic part, includes a flexible board having various electric conductor patterns formed on a synthetic resin film used as the board. The flexible board is formed integrally with a flexible flat cable comprising a synthetic resin film on which are formed electric conductor patterns electrically connected to the aforementioned various electric conductor patterns. When the molded resin casing is molded by injecting a molten synthetic resin, the flexible board is inserted in such a manner that the electric conductor patterns are exposed within the casing, thereby integrating the flexible board and synthetic resin casing, with the flexible flat cable extending outwardly from a side portion of the synthetic resin casing.