JP2005353323A - El sheet, and cover member for push button switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL sheet and a cover member for a push button switch of which power supplying capacity and bending resistant capacity can be easily improved. <P>SOLUTION: The cover member 1 for a push button switch comprises a key top part 2 and a supporting member for supporting the key top part 2. A base board member 20 comprises a circuit board 21, fixed contacts 22, 23, and a metallic disc screw member 24. The key top part 2 comprises a core material 7, and an insulation layer 6, the EL sheet 5, a resin film 4, and a protection layer 3 which are formed so as to cover the upper face and the side surfaces of the core member 7. The El sheet 5 is composed of a transparent electrode 51, a light emitting layer 52, a dielectric layer 53, and an opposing electrode 54. The transparent electrode is made a metal film. As the metal film, for example, a film made of gold, aluminum, nickel, chromium, indium, tin, or platinum, or a complex film of those elements is used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an EL sheet and a pushbutton switch cover member used in an electronic apparatus having an illumination function.

  2. Description of the Related Art Conventionally, for example, a push button switch cover member used in an input unit of a mobile phone or the like has an illumination function for illuminating a key top portion constituting the push button in order to ensure visibility in a dark place. Thereby, even when the user uses the mobile phone in a dark place, the function of each push button can be easily recognized.

Patent Documents 1 and 2 below disclose techniques related to a pushbutton switch in which an EL (electroluminescent) sheet is used as a member for realizing the illumination function described above. Here, the EL sheet is generally composed of a transparent electrode, a light emitting layer, a dielectric layer, and a counter electrode. And the ITO (indium tin oxide) ink is used for the transparent electrode contained in the EL sheet described in Patent Documents 1 and 2 described above.
JP 2000-285760 A JP 2000-212494 A

  By the way, when the transparent electrode of the EL sheet is formed of ITO ink, there is a problem that the luminance of the light emitting layer included in the EL sheet is lowered due to the low power supply capability of the ITO ink. Therefore, when high-luminance illumination is required, it is necessary to take another means such as providing an auxiliary electrode.

  In addition, since a film formed of a metal oxide such as ITO ink has poor stretchability, for example, when forming a transparent electrode made of such a film on a bent portion of a convex key top portion, for example. As a result of bending the transparent electrode, there is a possibility that cracks may occur, which may cause a conductive failure.

  Accordingly, an object of the present invention is to provide an EL sheet and a pushbutton switch cover member that can easily improve the power supply capability and the bending resistance in order to solve the above-described problems.

  The EL sheet of the present invention is an EL sheet having a transparent electrode, a light emitting layer, a dielectric layer and a counter electrode, wherein the transparent electrode is formed of a light-transmitting metal film. According to this invention, since the transparent electrode is formed of the metal film, it is possible to easily improve the power feeding ability and the bending resistance. In addition, since the metal film has a light-transmitting property, light emitted from the light-emitting layer can be illuminated to the outside.

  In the EL sheet of the present invention, the transmittance of the metal film described above is preferably 60% or more. In this way, the light emitted from the light emitting layer 52 can be illuminated to the outside more efficiently.

  In the EL sheet of the present invention, it is preferable that the metal film described above is formed of gold or aluminum. If it does in this way, electric power feeding capability and bending resistance can be improved more.

  According to the EL sheet and the pushbutton switch cover member of the present invention, the power feeding ability and the bending resistance can be easily improved.

  Embodiments of 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, a push button switch to which an EL sheet according to the embodiment is applied will be described with reference to FIG. FIG. 1 is a cross-sectional view of a pushbutton switch. The push button switch shown in FIG. 1 is roughly divided into a push button switch cover member 1 and a substrate member 20. The pushbutton switch cover member 1 includes a key top portion 2 and a support member (not shown) for supporting the key top portion 2 as necessary. The board member 20 includes a circuit board 21, fixed contacts 22 and 23, and a metal disc spring member 24 for connecting the fixed contact 22 and the fixed contact 23. The fixed contacts 22 and 23 and the metal disc spring member 24 are not necessarily included in the substrate member 20 and may be configured as contact members independent of the substrate member 20.

  The key top portion 2 includes a core material 7 that forms the main body of the key top portion 2, an insulating layer 6, an EL sheet 5, a resin film 4, and a protection layer formed so as to cover the upper surface and side surfaces of the core material 7. Layer 3. Further, between the resin film 4 and the protective layer 3, a printing unit 9 on which characters / symbols or the like represented by convex characters or extracted characters are printed is formed. A protrusion 71 for pressing the metal disc spring member 24 is formed on the surface of the core member 7 facing the fixed contact 22.

  The insulating layer 6 is desirably formed of a material having insulating properties and moisture resistance. Examples of such materials include polyester-based, acrylic-based resins, synthetic rubber-based, polycarbonate-based, silicone-based, fluorine-based resins, and composites thereof. Moreover, you may form the insulating layer 6 with an insulating film (for example, PET adhesive tape, CP leaf, etc.).

  The EL sheet 5 includes a transparent electrode 51, a light emitting layer 52, a dielectric layer 53, and a counter electrode 54.

  The transparent electrode 51 is formed of a metal film. Examples of the metal film include gold, aluminum, nickel, chromium, indium, tin, platinum, or a composite film thereof. Here, the metal film needs to have at least translucency, but it has been recognized that the luminous efficiency of the light emitting layer 52 tends to deteriorate when the transmittance of the metal film is less than 60%. Therefore, the transmittance is desirably 60% or more. On the other hand, it was recognized that the resistance value of the metal film tends to increase when the transmittance is 80% or more. Therefore, the transmittance is more preferably between 60 and 80%. The metal film is formed by, for example, electrodeposition, transfer, chemical plating, or vapor deposition.

  The light emitting layer 52 is formed, for example, by dispersing inorganic phosphor powder such as zinc sulfide coated with a moisture-proof coating in a binder. Examples of the binder include a fluororesin, a synthetic rubber, a polyester resin, an acrylic resin, an epoxy resin, or a copolymer thereof. Here, by selecting a binder having a high induction rate, the light emitting layer 52 can emit light with higher luminance.

  The dielectric layer 53 is formed, for example, by dispersing dielectric powder such as barium titanate or titanium oxide in a binder. The binder is the same as the binder used for the light emitting layer 52, and thus description thereof is omitted.

  The counter electrode 54 is made of, for example, a metal or alloy such as gold, silver, copper, or nickel, or a conductive filler such as carbon black or graphite, a polyester-based, acrylic-based, urethane-based, silicone-based, epoxy-based resin or rubber. Or a conductive film made of a dispersion of these copolymers. Moreover, you may form by the metal film | membrane which consists of metals or alloys, such as gold | metal | money, silver, copper, nickel, or these composite films. The composite film is formed by, for example, electrodeposition, transfer, chemical plating, or vapor deposition.

  The resin film 4 is formed of, for example, a film made of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polystyrene, polyamide, polymethyl methacrylate, polyurethane, and polyamide. Moreover, you may form with the film which consists of modified substances, such as these alloys and a copolymer, and may be formed with the multilayer product which laminated these several types of films.

[Example 1]
Next, Embodiment 1 of the present invention will be described with reference to FIG. 2 and FIG. Example 1 is an example when the transparent electrode 51 is formed of a gold metal film.

  First, as shown in FIG. 2A, a gold metal film 51 is placed on a PET film 4 having a thickness of 75 [μm] (Lumirror: product name, manufactured by Toray Industries, Inc.) with a total light transmittance of 75%. Vapor deposition was formed.

  Next, as shown in FIG. 2B, the light emitting layer 52 was formed on the gold metal film 51 by screen printing using the light emitting layer ink 8155N (EL medium: trade name, manufactured by DuPont). Further, the dielectric layer 53 was formed on the light emitting layer 52 and the metal film 51 by screen printing using dielectric layer ink 8153N (EL insulator paste: trade name, manufactured by DuPont). Further, the counter electrode 54 was formed on the dielectric layer 53 by screen printing using the counter electrode ink 7152 (EL carbon paste: trade name, manufactured by DuPont).

  Next, as shown in FIG. 2C, the terminal portion 10 for power connection is formed using terminal portion ink 7152 (EL carbon paste: trade name, manufactured by DuPont), and then the insulating layer ink IN The insulating layer 6 was formed using -10C (trade name, manufactured by Jujo Chemical Co., Ltd.). As a result, an EL sheet excellent in power supply capability and flexibility was obtained.

  Next, as shown in FIG. 3A, the printing part 9 is formed on the surface of the PET film 4 opposite to the surface on which the metal film 51 is deposited by using printing ink (HIPET 9300 series). Then, the protective layer 3 was formed on the printing unit 9 and the PET film 4 using a protective ink (HIPET 9300 series). Here, after the printing ink is printed or painted on the PET film 4, the printing unit 9 forms display characters and the like using a laser. The printing unit 9 may be formed on the PET film 4 immediately after the PET film 4 is formed. Moreover, you may form the protective layer 3 with the film for protection.

  Next, as shown in FIG. 3B, the EL sheet is drawn by compression molding using a mold at 130 ° C., and the drawn EL sheet and the polycarbonate resin forming the core material 7 are Integrated by injection molding. Thereby, the fall of the brightness | luminance by extending | stretching was suppressed and the member for pushbutton switches excellent in the flexibility was obtained at low cost. In addition, the shaping | molding method in drawing is not restricted to the compression shaping | molding mentioned above, For example, vacuum forming, pressure forming, etc. may be sufficient.

  Thus, by forming the transparent electrode 51 with a gold metal film, the power feeding ability and the bending resistance of the EL sheet can be improved as compared with the case where the EL sheet is formed with ITO ink. In general, since the transmittance of gold is low, it is possible to prevent a situation in which the color of the fluorescent pigment added to the light emitting layer 52 is seen through. Therefore, since the range of selection of the fluorescent pigment to be added can be expanded, various colors of light can be emitted. In addition, since gold color tone is added to the emission color, it is possible to emit high-quality light.

[Example 2]
Next, Embodiment 2 of the present invention will be described with reference to FIGS. Example 2 is an example in which the transparent electrode 51 is formed of an aluminum metal film. In addition, about Example 2, only the process different from the process demonstrated in Example 1 shall be demonstrated, and the description is abbreviate | omitted about the same process.

  First, as shown in FIG. 2A, an aluminum metal film 51 is formed on a polycarbonate alloy film 4 having a thickness of 125 [μm] (by hole: product name manufactured by Bayer Yakuhin Co., Ltd.). Vapor deposition was carried out to 60%. The steps from FIG. 2B to FIG. 3B are the same as the steps described in the first embodiment, and a description thereof is omitted.

  Thus, by forming the transparent electrode 51 with an aluminum metal film, the power feeding ability and the bending resistance of the EL sheet can be improved as compared with the case where it is formed with ITO ink. Further, the transparent electrode 51 can be formed at a lower cost.

It is sectional drawing of the pushbutton switch in embodiment. FIG. 5 is a cross-sectional view of the push button switch cover member for explaining a manufacturing process of the push button switch cover member in the first embodiment. It is sectional drawing of the cover member for pushbutton switches for demonstrating the manufacturing process of the cover member for pushbutton switches in Example 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cover member for pushbutton switches, 2 ... Key top part, 3 ... Protective layer, 4 ... Resin film, 5 ... EL sheet, 51 ... Transparent electrode, 52 ... Light emitting layer, 53 ... dielectric layer, 54 ... counter electrode, 6 ... insulating layer, 7 ... core material, 71 ... projection, 9 ... printing part, 10 ... Terminal part, 20 ... substrate member, 21 ... circuit board, 22, 23 ... fixed contact, 24 ... metal disc spring member.

Claims (4)

An EL sheet having a transparent electrode, a light emitting layer, a dielectric layer and a counter electrode,
The EL sheet, wherein the transparent electrode is formed of a translucent metal film. The EL sheet according to claim 1, wherein the transmittance of the metal film is 60% or more. The EL sheet according to claim 1, wherein the metal film is made of gold or aluminum. A cover member for a pushbutton switch, comprising: a key top portion whose upper surface and side surfaces of the main body are covered with the EL sheet according to claim 1.

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