JP4593411B2 - Cover member for pushbutton switch - Google Patents

Description

  The present invention relates to a pushbutton switch cover member used in a mobile electronic device.

  As a key sheet used for mobile electronic devices such as a mobile phone and a PDA (personal digital assistant), for example, a resin key top with a resin key top and a key sheet made of a rubber-like elastic body fixed with an adhesive is provided. There is a key sheet (see Patent Document 1 below). In the key sheet of Patent Document 1, due to variations in the amount of adhesive applied, the adhesive protrudes from the joint surface or the adhesive strength is insufficient, resulting in poor appearance due to adhesive marks and deterioration in operational feeling. This is a cause of various problems such as inviting.

As a key sheet to alleviate such problems, the following Patent Document 2 includes a resin key top in which a reservoir groove for storing an adhesive is formed on the joint surface of a rubber-like elastic key sheet with a resin key top. A key sheet is disclosed.
JP-A-5-83347 Japanese Patent Laying-Open No. 2005-50709

  By the way, the market demand for thinning mobile electronic devices is at a very high level. The same applies to the key sheet constituting the mobile electronic device. On the other hand, in the key sheet disclosed in Patent Document 2, a reservoir groove for storing an adhesive is formed in the key sheet of a rubber-like elastic body. When such a reservoir groove is formed on a thin key sheet, the reservoir groove forming portion becomes very thin, and the key sheet is easily broken.

  Therefore, in order to solve the above-described problems, the present invention provides a pushbutton switch cover member that can reduce the problems caused by variations in the amount of adhesive applied while maintaining the strength of the member. With the goal.

The cover member for a pushbutton switch of the present invention includes a resin key top, a key sheet formed on the lower side of the key top, and an adhesive layer formed between the key top and the key sheet. A recess is formed on a part of the bottom of the top, and the key sheet surface has fine irregularities that adjust the light diffusibility and illumination of the light source to make the key top recess inconspicuous from the outside. is formed, characterized in Rukoto.

According to the present invention, the recessed portion formed in a part of the bottom surface of the key top can function as a buffer that accommodates an excessively applied adhesive. Therefore, by setting the weighing value of the adhesive to be applied a little larger, even if the application amount varies due to weighing errors, the adhesive may protrude from the joint surface or the adhesive strength may be insufficient. Can reduce the situation. Further, since the indented portion is provided on the bottom surface of the relatively strong resin key top, there is no possibility that the key top is torn by providing the indented portion. Therefore, according to the present invention, it is possible to reduce problems caused by variations in the amount of adhesive applied while maintaining the strength of the member.
In addition, the fine unevenness formed on the surface of the key sheet can adjust the light diffusibility and illumination properties of the light source so that the recessed portion of the key top is not conspicuous from the outside.

  In the pushbutton switch cover member according to the present invention, the recess is preferably formed by providing a groove on the bottom surface of the key top. Since the recess is formed by providing a groove on the bottom surface of the key top, it is possible to keep the push button switch cover member thin.

  In the pushbutton switch cover member according to the present invention, the recess is preferably formed by providing a protrusion on the bottom surface of the key top. Since the recess is formed by providing the protrusion on the bottom surface of the key top, a situation in which the strength of the push button switch cover member is not reduced is not caused.

  According to the cover member for a pushbutton switch according to the present invention, it is possible to reduce problems caused by variations in the amount of adhesive applied while maintaining the strength of the member.

  Embodiments of a cover member for a push button switch according to the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

[First embodiment]
First, a first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a pushbutton switch cover member 1 according to the first embodiment. FIG. 2 is an enlarged view of a part of the cross-sectional view shown in FIG. The push button switch cover member 1 is roughly divided into a key top 10, a key sheet 20, and an adhesive layer 30.

  The key top 10 is made of, for example, a polycarbonate (PC) resin, a PMMA resin, an ABS resin, or a styrene resin. In addition, when the cover member 1 for pushbutton switches is a type irradiated from light sources, such as LED, each said resin which has translucency should just be used.

  A recessed portion 11 is formed on the bottom surface of the key top 10. The recess 11 is formed by providing a groove on the bottom surface of the key top 10. FIG. 3 is a plan view of the key top 10 when viewed from the bottom side. As shown in FIG. 3, the indented portion 11 is provided in an annular shape near the periphery of the bottom surface of the key top 10.

  The recess 11 is preferably provided near the periphery of the bottom surface of the key top 10. By providing the recessed portion 11 near the periphery of the bottom surface of the key top 10, the area of the portion existing inside the recessed portion 11, that is, the bonding area where the bottom surface of the key top 10 and the key sheet 20 are bonded via the adhesive layer is increased. This is because it can be done. Thereby, the adhesive strength between the key top 10 and the key sheet | seat 20 can be raised more. Specifically, the vicinity of the peripheral edge will be described. For example, when the major axis of the elliptical key top 10 shown in FIG. 3 is 10 [mm] and the minor axis is 5 [mm], the bottom surface of the key top 10 is It is preferable to form the outer periphery of the indented portion 11 so as to be located 0.3 to 0.5 [mm] inside the periphery of the bottom surface of the key top 10.

  A decoration layer 40 is formed on the top surface of the key top 10. The decorative layer 40 is composed of letters, numbers, symbols, figures, and the like, and is formed by, for example, printing, plating, painting, vapor deposition, hot stamping, or the like.

  The key sheet 20 includes a pressing portion 21 that protrudes downward. The pressing portion 21 is provided to press a metal disc spring (not shown) provided on the circuit board side. When the metal disc spring is pressed by the pressing portion 21, a fixed contact (not shown) is connected, and the push button switch becomes conductive.

  The key sheet 20 is made of, for example, synthetic rubber such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, butyl rubber, nitrile rubber, fluorine rubber, silicone rubber, natural rubber, urethane elastomer, or styrene elastomer. Here, when importance is attached to the durability of the key sheet 20, it is preferably formed of silicone rubber. Further, when the pushbutton switch cover member 1 is of a type that is irradiated from a light source such as an LED, the above-described rubber or elastomer having translucency may be used.

  The adhesive layer 30 is formed of, for example, an acrylic or polyester ultraviolet curable adhesive, a cyanoacrylate adhesive, a urethane adhesive, an epoxy adhesive, a rubber adhesive, or a silicone adhesive. Which of these adhesives is used is determined in consideration of compatibility with the material of the key top 10 and the key sheet 20. In addition, when the pushbutton switch cover member 1 is a type irradiated from a light source such as an LED, the above-described adhesives having translucency may be used.

  The adhesive layer 30 is formed, for example, using screen printing or a dispenser. Here, if pre-treatment such as plasma treatment, corona treatment, UV treatment, primer treatment, frame treatment or the like is performed on the joint surface of the key sheet 20 in advance, the adhesive strength can be further increased.

  According to the pushbutton switch cover member 1 in the first embodiment, the indented portion 11 formed by providing a groove on the bottom surface of the key top 10 functions as a buffer for storing the extra applied adhesive. be able to. Therefore, by setting the weighing value of the adhesive to be applied a little larger, even if the application amount varies due to weighing errors, the adhesive may protrude from the joint surface or the adhesive strength may be insufficient. Can reduce the situation. Further, since the indented portion 11 is provided on the bottom surface of the resin-made key top 10 having a relatively high strength, the situation in which the key top 10 is torn by providing the indented portion 11 does not occur. Further, since the recess 11 is formed by providing a groove on the bottom surface of the key top 10, the push button switch cover member 1 can be kept thin.

[Example 1]
Next, Example 1 of the push button switch cover member 1 according to the first embodiment will be described.

  First, a polycarbonate resin key top member (Caliber 301-22: trade name, manufactured by Sumitomo Dow Co., Ltd.) having a recess 11 on the bottom surface was injection molded.

  Next, using evaporative drying type ink (CAV Meiban: Seiko Advance Co., Ltd. product name), a decorative layer 40 made of symbols, numbers, letters, etc. is formed on the top surface of the key top member with a thickness of 5 μm. It was printed and dried under the conditions of a drying temperature of 80 ° C. and a drying time of 30 minutes. Thereby, the key top member by which the decoration layer 40 was formed in the top | upper surface was obtained.

  Next, excess portions such as runners and gates of the key top member were removed. Thereby, the key top 10 which has the hollow part 11 was obtained. Thereafter, the key top 10 was adsorbed and fixed to an adhesive jig on the key top side.

On the other hand, from 100 parts by weight of silicone rubber compound (DY32-6014U: product name manufactured by Toray Dow Corning Co., Ltd.) and 0.5 parts by weight of a crosslinking agent (RC-8: product name manufactured by Toray Dow Corning Co., Ltd.) the composed material, molding temperature 180 ° C., molding time 5 minutes, and compression molded under the conditions of molding pressure 180 kg / cm ^2, was molded silicone rubber key sheet member having a thickness of 0.5 mm.

  Next, the key sheet member was dried under the conditions of a drying temperature of 200 ° C. and a drying time of 60 minutes, and then excess portions such as burrs were removed. Thereby, the key sheet 20 which has translucency was obtained.

  Next, a primer (770: trade name, manufactured by Henkel Japan Co., Ltd.) was applied to the upper surface of the obtained key sheet 20, that is, the surface to which the key top 10 was adhered, and was naturally dried for 5 minutes. Thereafter, the key sheet 20 was fixed by adsorbing to the key sheet side bonding jig.

  Next, a cyanoacrylate adhesive (401: trade name, manufactured by Henkel Japan Co., Ltd.) was applied to the surface of the key sheet 20 on which the primer was applied by a dispenser method.

Next, the key top 10 fixed to the key jig on the key top side and the key sheet 20 fixed to the key sheet side bonding jig are bonded together, and 0.1 kg / cm is attached to the bonding jig. It was hardened and adhered by holding for 30 seconds while applying a pressure of ² . As a result, it was possible to obtain the push button switch cover member 1 which is more efficient and high quality than the conventional one.

  In the first embodiment described above, the recess 11 is formed in an annular shape when viewed from the bottom surface side of the key top 10, but the shape of the recess 11 is not limited to this. For example, it may be a polygon or a shape imitating a symbol or figure such as a star shape or a heart shape. By using the key top 10 having the recessed portions 11 of various shapes as the cover member for the illuminated push button switch, the shape of the recessed portion 11 is used as a decorative pattern when illuminated by a light source such as an LED. Can be used.

  Further, a printing layer having a light shielding property may be further formed on the bottom surface side of the key top 10. By forming such a printed layer, the recessed portion 11 formed on the bottom surface of the key top 10 can be made inconspicuous from the outside. Note that the degree of light blocking ability is not limited as long as light transmitted from the light source such as an LED or light transmitted from the outside can be attenuated. This print layer can be formed by mixing a base resin with a filler and printing. As the base resin, for example, resins such as acrylic, EVA (ethylene vinyl acetate copolymer), PVC (vinyl chloride), urethane, epoxy, polyester, polycarbonate, or a composite resin of these can be used. As the filler, for example, a white pigment such as titanium oxide or pearl mica can be used. The thickness of the printing layer may be 5 [μm] or more, and more preferably 8 to 20 [μm].

  Moreover, it is good also as providing fine unevenness | corrugation in either surface of the key sheet 20, More preferably, both surfaces. By providing such irregularities, it becomes possible to adjust the diffusibility and illumination properties of light emitted from a light source such as an LED, so that the recessed portion 11 can be made inconspicuous from the outside. Moreover, since the surface area of the key sheet 20 can be increased by providing unevenness, the adhesiveness between the key sheet 20 and the adhesive layer 30 can be improved. Furthermore, by providing the unevenness, it is possible to reduce a contact area with an unnecessary object such as dust, so that it is possible to reduce a situation where the unnecessary object adheres to the surface of the key sheet. As a method of processing the unevenness, for example, there is a method of performing unevenness processing in advance on a cavity surface of a mold for forming the key sheet 20 and transferring the unevenness to the key sheet 20 when the key sheet 20 is formed. Further, for example, the unevenness may be simply processed using a plast process.

  Moreover, in 1st Embodiment mentioned above, although the decoration layer 40 is formed in the top | upper surface of the key top 10, the place which forms the decoration layer 40 is not limited to the top | upper surface of the key top 10. FIG. For example, a decorative layer may be formed on the bottom surface of the key top 10. When the decoration layer is formed on the bottom surface of the key top 10, the key top 10 is formed of a resin having transparency. Thereby, the decoration layer can be visually recognized from the outside through the key top 10.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of the pushbutton switch cover member according to the second embodiment. The push button switch cover member 2 in the second embodiment is different from the push button switch cover member 1 in the first embodiment. First, in the push button switch cover member 1 in the first embodiment, the recess 11 In contrast to the push button switch cover member 2 according to the second embodiment, the recess 11s is formed by providing the protrusion 12 on the bottom of the key top 10s, whereas the groove is formed on the bottom of the top 10. It is a point formed inside. Further, in the push button switch cover member 1 in the first embodiment, the decorative layer 40 is formed on the top surface of the key top 10, whereas in the push button switch cover member 2 in the second embodiment, the decorative layer 40 is added. It is also different in that the decoration layer 40 is formed on the bottom surface of the key top 10s.

  As shown in FIG. 4, the decoration layer 40, the protrusion part 12, and the hollow part 11s are formed in the bottom face of the key top 10s. The indented portion 11s is formed inside the protrusion 12 provided on the bottom surface of the key top 10s. FIG. 5 is a plan view of the key top 10s as viewed from the bottom side. As shown in FIG. 5, the recessed portion 11s is formed inside a protrusion 12 provided in a substantially annular shape near the periphery of the bottom surface of the key top 10s. As shown in FIG. 4, the protrusion 12 is formed in a bank-like shape on the bottom surface of the key top 10s, and as shown in FIG. 5, the protrusion 12 is formed in a substantially annular shape on the bottom surface of the key top 10s. Thereby, the recessed part 11s is formed inside the protrusion part 12, and an adhesive can be accommodated in this recessed part 11s.

  The protrusion 12 is formed of, for example, a resin such as acrylic, EVA, PVC, urethane, epoxy, polyester, or polycarbonate, or a resin that combines these, for example, by screen printing, pad printing, or using a dispenser.

  The protrusion 12 is preferably provided near the periphery of the bottom surface of the key top 10s. By providing the protrusion 12 near the periphery of the bottom surface of the key top 10s, the area of the portion existing inside the protrusion 12, that is, the bonding area where the bottom surface of the key top 10s and the key sheet 20 are bonded via the adhesive layer is increased. This is because it can be done. Thereby, the adhesive strength between the key top 10s and the key sheet 20 can be further increased. Specifically, the vicinity of the peripheral edge will be described. For example, when the major axis of the elliptical key top 10s shown in FIG. 5 is 10 [mm] and the minor axis is 5 [mm], the bottom surface of the key top 10s is The outer periphery of the protrusion 12 is formed so as to be located 0.3 to 0.5 [mm] inside from the periphery of the bottom surface of the key top 10s. When the outer periphery of the protrusion 12 is positioned less than 0.3 mm from the periphery of the bottom surface of the key top 10s, it becomes difficult to align the key top 10s and the key sheet 20, and during bonding. Workability and stability after bonding are reduced.

  The height of the protrusion 12 is preferably 5 [μm] or more, and more preferably 8 to 20 [μm]. When the height of the protrusion 12 is 3 [μm] or less, the adhesive tends to overflow from the protrusion when the key top and the key sheet are bonded. On the other hand, if the height of the protruding portion 12 is 25 [μm] or more, the time required for the ink forming the protruding portion 12 to be cured becomes longer. Therefore, the protruding portion 12 collapses until the ink is cured. There is a risk that. In addition, when the protrusion 12 is formed of UV-based ink and the height of the protrusion 12 is 25 [μm] or more, a portion where the protrusion 12 is too thick to receive ultraviolet rays appears. Becomes an uncured state.

Table 1 shows the results of the evaluation test regarding the ink curing condition and the adhesive overflow condition.

  The degree of curing of the ink after forming the protrusions 12 shown in Table 1 was evaluated as follows. When stickiness was felt when the printed ink surface was touched with a fingertip, it was evaluated as an uncured state and marked with “x”. On the other hand, when stickiness was not felt, it evaluated that it was a hardening state and gave "(circle)".

  Moreover, the overflow of the adhesive after bonding the key top and the key sheet shown in Table 1 was evaluated as follows. After bonding the key top and the key sheet, the product was visually observed from the back side, and when overflow of the adhesive was confirmed, it was evaluated that there was an overflow, and “X” was given. On the other hand, when no overflow of the adhesive was confirmed, it was evaluated that there was no overflow and was marked with “◯”.

  As shown in Table 1, when the evaluation test was performed by changing the height of the protrusion 12 within the range of 3 to 25 [μm], the cured state of the ink was 3 to 23 [μm]. However, at 25 [μm], it was evaluated as an uncured state.

  Further, regarding the overflow of the adhesive, 3 [μm] was evaluated as being in a state of overflow, but from 5 to 25 [μm], it was evaluated as being in a state of no overflow.

  In addition, when performing the evaluation test regarding Table 1, the following materials were used for each member. Polycarbonate resin (Caliber 301-22: trade name, manufactured by Sumitomo Dow Co., Ltd.) is used for the key top, and UV curable ink (PF4200: trade name, manufactured by Jujo Chemical Co., Ltd.) is used for the protrusions 12. It was. Moreover, the ink was dried using the metal halide lamp for ultraviolet curing ([D] bulb: brand name made by Fusion UV Systems Japan Co., Ltd.). Further, the evaluation test was performed with the width of the protrusion 12 being 0.5 [μm].

  Next, the width of the protrusion 12 is preferably 0.5 to 1.0 [mm], and more preferably 0.5 to 0.7 [mm]. When the width of the protrusion 12 is less than 0.5 [mm], the protrusion is liable to be faint, making it difficult to stably print the protrusion, and the adhesive is liable to overflow from the protrusion. On the other hand, when the width of the protrusion 12 exceeds 1.0 [mm], the bonding area where the key top bottom surface and the key sheet are bonded via the adhesive layer is reduced, and the adhesive strength is reduced. The bonding area is preferably 25% or more with respect to the bottom area of the key top.

Table 2 shows the results of evaluation tests on the degree of ink fading, adhesive overflow, and product adhesion.

  The degree of ink fading after forming the protrusions 12 shown in Table 2 and the overflow of the adhesive after the key top and the key sheet were bonded were evaluated as follows. When the key top is visually observed from the back side after forming the protrusions 12, when the ink is faint or when the product is visually observed from the back side after the key top and the key sheet are bonded, When an overflow was confirmed, it was evaluated that there was a blur or overflow, and an “x” was attached. On the other hand, when no fading was confirmed in the ink or when no overflow of the adhesive was confirmed, the ink was evaluated as being in a state where there was no fading or overflowing, and “◯” was given.

  Moreover, about the adhesion | attachment condition after adhere | attaching the key top and key sheet which are shown in Table 2, it evaluated as follows. When the key top was pulled vertically at a speed of 50 [mm / min] and the key sheet was found to be broken, it was evaluated that the adhesive strength was sufficient, and marked with “◯”. On the other hand, when no breakage was observed in the key sheet and it was recognized that the key top and the key sheet were separated from each other, the adhesive strength was evaluated as insufficient, and an “x” was given.

  This evaluation test was performed using a key top having a circular bottom surface and a bottom surface diameter of 5 [mm] and a key top having 10 [mm].

  First, as shown in Table 2, the evaluation test was performed by changing the width of the protrusion 12 of the key top having a bottom diameter of 5 [mm] within a range of 0.3 to 1.0 [mm]. With regard to the degree of ink fading and adhesive overflow, it was evaluated that there was faintness or overflow at 0.3 [mm], but at 0.5 to 1.0 [mm], it was faint. It was evaluated that there was no overflow. As for the bonding condition, it was evaluated that the adhesive strength was sufficient at 0.3 to 0.7 [mm], but was evaluated as insufficient at 1.0 [mm]. .

  Note that the ratio of the bonding area (the area where the key top bottom surface and the key sheet are bonded to each other through the adhesive layer) to the bottom area of the key top is 0.3, 0.5, 0.7, In the case of 1.0 [mm], they were 46%, 36%, 27%, and 16%, respectively.

  Next, as shown in Table 2, an evaluation test was performed by changing the width of the key top protrusion 12 having a bottom diameter of 10 [mm] within a range of 0.3 to 1.0 [mm]. However, with regard to the degree of ink fading and adhesive overflow, it was evaluated that there was a faintness or overflow at 0.3 [mm], but at 0.5 to 1.0 [mm], it was faint. It was evaluated that there was no overflow. Moreover, about the adhesive condition, it was evaluated that adhesive strength was enough in the whole range of 0.3-1.0 [mm].

  Note that the ratio of the bonding area (the area where the key top bottom surface and the key sheet are bonded to each other through the adhesive layer) to the bottom area of the key top is 0.3, 0.5, 0.7, In the case of 1.0 [mm], they were 71%, 64%, 58%, and 49%, respectively.

Moreover, in performing the evaluation test regarding Table 2, the following materials were used for each member. Polycarbonate resin (Caliber 301-22: trade name, manufactured by Sumitomo Dow Co., Ltd.) is used for the key top, and UV curable ink (PF4200: product name, manufactured by Jujo Chemical Co., Ltd.) is used for the protrusion 12. It was. Moreover, the ink was dried using the metal halide lamp for ultraviolet curing ([D] bulb: brand name made by Fusion UV Systems Japan Co., Ltd.). Further, the adhesive layer 30 has an ultraviolet curable adhesive (ThreeBond 3042H: trade name, manufactured by Three Bond Co., Ltd.) 100 parts by weight and a silane coupling agent (KBM-603: trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) 0. What mix | blended 5 weight part was used. A key sheet made of silicone rubber was used as the key sheet. This silicone rubber key sheet has a wavelength of 184.9 [nm] and 253.7 [nm] using a batch type UV cleaning furnace (VUM-3073-B: trade name, manufactured by Oak Manufacturing Co., Ltd.). Ultraviolet rays were irradiated under conditions of 1200 [mJ / cm ² ]. Further, the height of the protrusion 12 was set to 10 [μm], and the outer periphery of the protrusion 12 was formed to be located 0.5 [mm] inside from the periphery of the bottom surface of the key top 10.

  As shown in FIG. 5, air grooves 13 are provided at two predetermined positions of the protrusion 12. By providing the air groove 13 in a part of the projecting portion 12, bubbles mixed when the key top 10 s and the key sheet 20 are bonded can be extracted from the air groove 13. The air groove 13 is formed by providing, for example, a notch with a width of 0.3 to 0.5 [mm] in the protrusion 12.

  Since other components are the same as those in the first embodiment, the description thereof is omitted.

  According to the pushbutton switch cover member 2 in the second embodiment, the recessed portion 11 s formed by providing the protrusion 12 on the bottom surface of the key top 10 s functions as a buffer that accommodates the extra applied adhesive. Can be demonstrated. Therefore, by setting the weighing value of the adhesive to be applied a little larger, even if the application amount varies due to weighing errors, the adhesive may protrude from the joint surface or the adhesive strength may be insufficient. Can reduce the situation. Further, since the recessed portion 11s is formed by providing the protrusion 12 on the bottom surface of the key top 10s, there is no possibility that the strength of the pushbutton switch cover member 2 is lowered.

[Example 2]
Next, Example 2 of the push button switch cover member 2 in the second embodiment will be described.

  First, a key top member made of polycarbonate resin (Caliber 301-22: trade name, manufactured by Sumitomo Dow Co., Ltd.) was injection molded.

  Next, a decorative layer 40 made of symbols, numbers, letters, etc. is printed at a thickness of 5 μm on the bottom surface of the key top member using evaporative drying ink (CAV Meiban: product name manufactured by Seiko Advance Co., Ltd.). And dried at a drying temperature of 80 ° C. and a drying time of 30 minutes. Thereby, the key top member by which the decoration layer 40 was formed in the bottom face was obtained.

Next, an annular protrusion having an air groove 13 is formed on the portion located 0.5 mm inside from the periphery of the bottom surface of the key top member by using ultraviolet curable ink (UVPAL: trade name manufactured by Teikoku Ink Manufacturing Co., Ltd.). 12, printed in width 0.5 mm, thickness of 5 [mu] m, UV-curing metal halide lamp: using ([D] bulb Fusion UV Systems Japan Co., trade name), the integrated light quantity 250 mJ / cm ² conditions And dried. Thereby, the key top member which has the hollow part 11s was obtained.

  Next, surplus portions such as runners and gates of the key top member having the recess 11s were removed. As a result, a key top 10s having a recess 11s was obtained. Thereafter, the key top 10s was adsorbed and fixed to a bonding jig on the key top side.

On the other hand, from 100 parts by weight of silicone rubber compound (DY32-6014U: product name manufactured by Toray Dow Corning Co., Ltd.) and 0.5 parts by weight of a crosslinking agent (RC-8: product name manufactured by Toray Dow Corning Co., Ltd.) The resulting raw material was compression molded under the conditions of a molding temperature of 180 ° C., a molding time of 5 minutes, and a molding pressure of 180 kg / cm ² to form a silicone rubber key sheet member having a thickness of 0.5 mm.

  Next, the key sheet member was dried under the conditions of a drying temperature of 200 ° C. and a drying time of 60 minutes, and then excess portions such as burrs were removed. Thereby, the key sheet 20 which has translucency was obtained.

Next, on the upper surface of the obtained key sheet 20, that is, the surface to which the key top 10s is bonded, using a batch type ultraviolet cleaning furnace (VUM-3073-B: trade name, manufactured by Oak Manufacturing Co., Ltd.), 184.9. Ultraviolet rays having wavelengths of [nm] and 253.7 [nm] were irradiated under conditions of 1200 [mJ / cm ² ]. Thereafter, the key sheet 20 was adsorbed and fixed to a bonding jig on the key sheet side.

  Next, on the surface of the key sheet 20 irradiated with ultraviolet rays, 100 parts by weight of an ultraviolet curable adhesive (ThreeBond 3042H: trade name, manufactured by Three Bond Co., Ltd.) and a silane coupling agent (KBM-603: Shin-Etsu Chemical Co., Ltd.) (Product name) 0.5 parts by weight was transferred using a transfer jig.

  Next, the key top 10s fixed to the key top side bonding jig and the key sheet 20 fixed to the key sheet side bonding jig were bonded together.

Next, using an ultraviolet irradiation conveyor (metal halide, 120 W / cm, M015L312: trade name, manufactured by Eye Graphics Co., Ltd.), ultraviolet rays having a wavelength of 300 to 450 [nm] are irradiated under the condition of 2000 mJ / cm ^2. Then, an ultraviolet curable adhesive was cured and adhered. As a result, it was possible to obtain the push button switch cover member 2 which is more efficient and high quality than before.

  In addition, in 2nd Embodiment mentioned above, although the air groove 13 is provided in two places of the projection part 12, the place which provides an air groove is not restricted to this. The air groove may be provided only at one place, or may be provided at three or more places. Further, it is not always necessary to provide an air groove.

  Moreover, it is good also as forming the printing layer which has light-shielding property in the bottom face side of the keytop 10s. The degree of light shielding property of the print layer is the same as that of the print layer in the modified example of the first embodiment described above. By forming such a printing layer, the protrusion 12 formed on the bottom surface of the key top 10s can be made inconspicuous from the outside. Since the method for forming the print layer and the thickness of the print layer are the same as those in the modified example of the first embodiment described above, the description thereof is omitted.

  Moreover, it is good also as providing fine unevenness | corrugation in either surface of the key sheet 20, More preferably, both surfaces. About the effect by providing such unevenness | corrugation and the method of processing unevenness are the same as the effect in the modification of 1st Embodiment mentioned above, and the processing method, The description is abbreviate | omitted.

  Moreover, in 2nd Embodiment mentioned above, although the decoration layer 40 is formed in the bottom face of the key top 10s, the place which forms the decoration layer 40 is not limited to the bottom face of the key top 10s. For example, a decorative layer may be formed on the top surface of the key top 10s.

It is sectional drawing of the cover member for pushbutton switches in 1st Embodiment. It is the figure which expanded and showed a part of sectional drawing shown in FIG. It is a top view which shows the bottom face of the keytop shown in FIG. It is sectional drawing of the cover member for pushbutton switches in 2nd Embodiment. It is a top view which shows the bottom face of the keytop shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Cover member for pushbutton switches 10, 10, 10s ... Key top, 11, 11s ... Recessed part, 12 ... Projection part, 13 ... Air groove, 20 ... Key sheet , 21 ... pressing portion, 30 ... adhesive layer, 40 ... decorative layer.

Claims (3)

Resin key top,
A key sheet formed on the lower side of the key top;
An adhesive layer formed between the key top and the key sheet,
The part of the bottom surface of the key top, the recess portion is formed,
Wherein the surface of the key sheet, and adjust the light diffusivity and illumination of the light source, for push button switches according to the fine irregularities of the recess made inconspicuous from the outside is formed, characterized in Rukoto of the key top Cover member. 2. The pushbutton switch cover member according to claim 1, wherein the recess is formed by providing a groove on a bottom surface of the key top. 2. The pushbutton switch cover member according to claim 1, wherein the recess is formed by providing a protrusion on a bottom surface of the key top.

Images