JP2006079863A - Member for illuminated type push-button switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member for an illuminated type push-button switch capable of stably attaining brightness almost as designed with an insulation property of a light-emitting area maintained. <P>SOLUTION: In the member for the illuminated type push-button switch 1 in which a transparent electrode layer 12 of an EL sheet 5 equipped with a plane light-emitting part 4 with a transparent electrode layer 12, a light-emitting layer 13, a dielectric layer 14 and an opposing electrode layer 15 laminated in this sequence is arranged at a top face 18 side of a key-top main body 2, and at least one key top part 6 elevated from a flat part of the EL sheet 5 is formed so as to cover a top face and side faces of a core material 3 forming a three-dimensional shape of the key-top main body 2, at least one ion diffusion prevention layer 17 is provided between the transparent electrode layer 12 and the opposing electrode layer 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a member for an illuminated pushbutton switch of, for example, a mobile communication device such as a mobile phone or a PDA, a CD player, an MD player, a small tape recorder, or a small electric / electronic device mounted in an automobile.

  Conventionally, an illumination type pushbutton switch is used in an input device such as a mobile communication device. In the illumination type push button switch member used for the push button switch in this type of device, a so-called illumination function for illuminating the display portion showing the function of the push button switch is required at night.

  As a member for a push button switch used in an input device such as a cellular phone, an EL sheet having a light emitting display portion provided on the top surface side of the key top and having a surface light emitting portion emitting self light on the display portion The technique which employ | adopts is disclosed (refer patent document 1).

In this EL sheet, a transparent electrode layer made of a conductive polymer, a light emitting layer such as inorganic EL, a dielectric layer, and a counter electrode layer are sequentially laminated on a colored layer formed on a base film. A pushbutton switch member is obtained by molding the EL sheet having the surface light emitter portion obtained in this way into a key top shape.
JP 2004-6105 A

  However, in the EL sheet used for the conventional pushbutton switch member as described above, the metal filler of the counter electrode layer, the bromine in the transparent electrode layer, Impurities such as chlorine are ionized and further diffused. As a result, the insulation between the transparent electrode layer and the back electrode layer is deteriorated, resulting in a decrease in luminance, black spots due to partial short-circuiting, and non-lighting. There was a bug to do. This phenomenon is further promoted under high humidity.

  Therefore, the present invention is an illuminated pushbutton that can maintain the insulation of the light emitting region and stably emit the luminance almost as designed in order to solve the problems of the conventional pushbutton switch member employing the EL sheet. It is an object to provide a switch member.

  In order to achieve the above object, in the invention according to claim 1, the transparent electrode layer of an EL sheet having a surface light emitter portion laminated in the order of a transparent electrode layer, a light emitter layer, a dielectric layer, and a counter electrode layer is provided. At least one or more key top portions arranged on the top surface side of the key top and raised from the flat portion of the EL sheet so as to cover the upper surface and the side surface of the core material forming the three-dimensional shape of the key top In the illumination type pushbutton switch member having the above structure, at least one ion diffusion prevention layer is provided between the transparent electrode layer and the counter electrode layer.

  Further, in the invention according to claim 2, in addition to the structure of claim 1, the ion diffusion prevention layer is obtained by dispersing a conductive filler mainly composed of nickel or carbon in a synthetic resin, and An ion diffusion preventing layer is provided in contact with the counter electrode layer.

  Further, in the invention according to claim 3, in addition to the structure of claim 1 or 2, the ion diffusion preventing layer is made by dispersing a dielectric having a dielectric constant lower than that of the dielectric used for the dielectric layer in the synthetic resin. The ion diffusion preventing layer is provided in contact with the dielectric layer.

  With the above configuration, according to the first aspect of the invention, since the ion diffusion preventing layer is provided between the transparent electrode layer and the counter electrode layer, the metal filler of the counter electrode layer or the transparent electrode layer is provided. Impurities such as bromine and chlorine inside are prevented from ionizing and further diffusing, so that the insulation between the transparent electrode layer and the counter electrode layer in the light emitting region is maintained. It is possible to provide a member for an illuminated pushbutton switch that stably emits luminance almost as designed.

  According to the second aspect of the present invention, the ion diffusion prevention layer is obtained by dispersing a conductive filler mainly composed of nickel or carbon in a synthetic resin, and the ion diffusion prevention layer is a counter electrode layer. In addition to the effect of the first aspect, the conductive performance of the transparent electrode layer can be compensated.

  According to a third aspect of the present invention, the ion diffusion preventing layer is obtained by dispersing a dielectric having a dielectric constant lower than that of the dielectric used in the dielectric layer in the synthetic resin, and preventing the ion diffusion. Since the layer is provided in contact with the dielectric layer, the moisture resistance is improved in addition to the effect of the first or second aspect.

  FIG. 1 is a cross-sectional view of a main part showing a member for an illuminated pushbutton switch according to an embodiment of the present invention.

  The illuminated pushbutton switch member 1 according to the embodiment shown in FIG. 1 includes a core member 3 that forms a key top body 2 and a surface light emitter that is formed so as to cover the upper surface and side surfaces of the core member 3. 4, and the core material 3 determines the substantial shape of the key top portion 6. In addition, a projecting presser 9 for pressing a movable contact 8 such as a metal disc spring corresponding to the fixed contact 7 is provided on the lower surface of the core member 3.

  As the material of the core material 3, a hard resin such as polycarbonate, acrylic, ABS, or an elastomer such as silicone rubber can be used.

  The EL sheet 5 is laminated in the order of the base film 10, the decorative layer 11, the transparent electrode layer 12, the light emitter layer 13, the dielectric layer 14, the counter electrode layer 15, and the protective layer 16. At least one ion diffusion preventing layer 17 is provided between the counter electrode layers 15. When an alternating voltage is applied between the two electrodes of the transparent electrode layer 12 and the counter electrode layer 15 facing each other, the phosphor in the light emitter layer 13 sandwiched between the two electrodes is excited and emits light. The EL sheet 5 is arranged so that the base film 10 side with the transparent electrode layer 12 is the skin of the key top body 2 of the illuminated pushbutton switch member 1.

  Examples of the material of the base film 10 include various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, acrylic, polystyrene, polyimide, polyamide, polyphenyl sulfite, polyurethane, and polyvinyl chloride. Polystyrene-based, polyester-based, and polyamide-based thermoplastic elastomers may also be used. These may be homopolymers or copolymers. A modified product such as an alloy can also be used. As for the thickness of the base film 10, 12-500 micrometers is common.

  A decorative layer 11 is provided on the back side of the base film 10, and a display unit 19 such as characters, symbols, or symbols is formed at a location corresponding to the top surface 18 of the key top body 2. Due to the difference in transmittance, the display unit 19 is configured to be easily visible when the surface light emitter unit 4 is illuminated. For example, it can be set as the structure which illuminates a background by forming a character and a symbol with a coating film with low transmittance | permeability, and forming a background with a coating film with high transmittance | permeability. Moreover, it can be set as the structure which illuminates centering on a character and a symbol by forming a character and a symbol with a coating film with high transmittance, and forming a background with a coating film with low transmittance.

  On the back side of the decorative layer 11, a transparent electrode layer 12 that serves as one electrode of the EL sheet 5 is provided. As the transparent electrode layer 12, it is necessary to use a material that can withstand stretching during molding. For example, a conductive polymer can be used. In particular, a highly conductive derivative such as polypyrrole, polythiophene, or polyaniline having transparency is preferable. In addition, before and after the transparent electrode layer 12, an adhesive layer (not shown) for enhancing the adhesion with a layer adjacent to the transparent electrode layer 12 can be provided. Examples of the material for the adhesive layer include polyester-based, acrylic-based, urethane-based resins, and various rubbers.

  If necessary, an opaque but highly conductive auxiliary electrode (not shown) such as carbon or silver is laminated on the transparent electrode layer 12 outside the light emitting region to compensate for the conductive performance of the transparent electrode layer 12. May be.

  As the phosphor layer 13 formed on the back side of the transparent electrode layer 12 where light emission is necessary, for example, an inorganic phosphor powder such as zinc sulfide subjected to moisture-proof treatment such as alumina is used in a synthetic resin (including an elastomer). What was dispersed in can be used. Synthetic resins include fluorine-based, polyester-based, acrylic-based, and epoxy-based resins, and these may be homopolymers or copolymers. Moreover, you may use individually or in combination. By using a synthetic resin having a high dielectric constant, the light emitter layer 13 can emit light with higher luminance.

  A dielectric layer 14 is provided on the back side of the light emitting layer 13. For the dielectric layer 14, for example, a dielectric powder having a high dielectric constant, such as barium titanate, potassium titanate, titanium oxide, or the like, is used as a total solid content of a synthetic resin (synthetic resin, dielectric) similar to the light emitting layer 13. , Other additives, etc.) 40 to 90 parts by mass and 100 parts by mass dispersed can be used. When such a high dielectric material is used, the light emission efficiency can be increased.

  On the back side of the dielectric layer 14, a counter electrode layer 15 that forms the other electrode of the EL sheet 5 is provided. By adopting a conductive filler such as silver giving priority to the conductive performance for the counter electrode layer 15 and using the ion diffusion preventing layer 17, the EL sheet 5 having good environmental stability can be obtained.

  As the conductive filler, gold, silver, copper, carbon, nickel, or an alloy thereof can be used. Among them, silver excellent in conductivity is preferable. Examples of the synthetic resin include various resins such as polyester, acrylic, urethane, fluorine, silicone, and epoxy. These resins may be a homopolymer or a copolymer. Moreover, you may use individually or in combination.

  Furthermore, a protective layer 16 is formed on the counter electrode layer 15 to cover the layers stacked so far. The protective layer 16 is a layer having both a function of electrically insulating and a function of adhering to the core material 3.

  Between the transparent electrode layer 12 and the counter electrode layer 15, at least one ion diffusion preventing layer 17 for preventing diffusion of impurity ions eluted from the transparent electrode layer 12 and the counter electrode layer 15 is provided. The ion diffusion preventing layer 17 has a function of delaying or capturing the diffusion of impurity ions between the layers and must be an electrically stable layer. If it is a colorless or light-colored transparent material, it may be provided between the transparent electrode layer 12 and the light emitter layer 13, but the ion diffusion prevention layer 17 is provided below the light emitter layer 13, that is, on the counter electrode layer 15 side. As a result, it is possible to efficiently prevent deterioration of the light emitter without worrying about the color of the material.

  For example, by using a material in which a conductive filler mainly composed of carbon or nickel is dispersed in a synthetic resin as the ion diffusion preventing layer 17 between the dielectric layer 14 and the counter electrode layer 15, the transparent electrode layer 12 or The passage and diffusion of impurity ions eluted from the counter electrode layer 15 can be prevented, insulation deterioration can be prevented, and light emission reliability can be maintained over a long period of time. In addition, the conductive filler is 3 to 50 parts by mass with respect to 100 parts by mass of the solid content of the ion diffusion preventing layer 17, and the amount of the synthetic resin is increased with respect to the conductive filler, thereby providing excellent moldability. The ion diffusion preventing layer 17 can be obtained. As the conductive filler, electrically stable carbon or nickel is preferable, but a small amount of other metals may be mixed for the purpose of reducing the resistance value. Examples of the synthetic resin include various resins such as polyester, acrylic, urethane, fluorine, silicone, and epoxy. These resins may be a homopolymer or a copolymer. Moreover, you may use individually or in combination. Among these, resins having a low moisture absorption rate such as fluorine and epoxy are preferable.

  Further, in order to minimize the attenuation of luminous efficiency and enhance the insulation performance, an ion diffusion preventing layer 17 in which a dielectric is dispersed in a synthetic resin can be provided in contact with the dielectric layer 14. By setting the dielectric constant of the ion diffusion preventing layer 17 itself to be smaller than the dielectric constant of the dielectric layer 14, the passage of impurity ions eluted from the transparent electrode layer 12 and the counter electrode layer 15 is somewhat sacrificed in light emission efficiency. Therefore, diffusion can be prevented, insulation deterioration can be prevented, and light emission reliability can be maintained over a long period of time. As the method, the amount of dielectric added to the synthetic resin may be controlled, or a dielectric or synthetic resin having a low dielectric constant may be used.

  As the addition amount of the dielectric material, the effect of preventing ion diffusion can be obtained by adding a small amount of dielectric material to the synthetic resin. However, if the addition amount of the dielectric material is simply reduced, the insulating property of the ion diffusion prevention layer 17 is improved. However, the electric field to the light emitting layer is lowered and the luminance is lowered. Therefore, it is preferable to control the film thickness to be thin and maintain a constant capacitance. On the contrary, if the dielectric exceeds 70 parts by mass with respect to 100 parts by mass of the total solid content of the ion diffusion preventing layer 17, the ductility of the ion diffusion preventing layer 17 itself is lowered and it becomes difficult to follow the film at the time of molding. Or disconnection easily occurs, resulting in a decrease in luminance or non-lighting. When the ion diffusion prevention layer 17 in which a dielectric material of 40 to 60 parts by mass is dispersed in a synthetic resin is used with respect to 100 parts by mass of the total solid content of the ion diffusion prevention layer 17, the moldability is good and the influence of the variation in film thickness. You do n’t have to worry too much.

  As the material of the ion diffusion preventing layer 17, the same material as that of the dielectric layer 14 can be used. However, by deliberately reducing the blending amount of the dielectric material compared to the dielectric layer 14, the luminous efficiency is somewhat sacrificed. However, it is possible to prevent the impurity ions eluted from the transparent electrode layer 12 and the counter electrode layer 15 from passing and diffusing, to prevent insulation deterioration, and to maintain light emission reliability over a long period of time. It is preferable to use a dielectric such as titanium oxide having a high insulating property among the dielectrics because the insulating property between the transparent electrode layer 12 and the counter electrode layer 15 is increased. The insulating property and the dielectric constant are contradictory, and the dielectric constant of the ion diffusion preventing layer 17 is preferably a dielectric having a dielectric constant of about 70% or less of the dielectric used for the dielectric layer 14. Furthermore, impurity ions can be efficiently trapped by adding an ion exchanger. Examples of the synthetic resin include various resins such as polyester, acrylic, urethane, fluorine, silicone, or polyepoxy. These resins may be a homopolymer or a copolymer. Moreover, you may use individually or in combination. Among these, resins having a low moisture absorption rate such as fluorine-based resins are preferable.

  Further, the ion diffusion preventing layer 16 can be formed of only synthetic resin without adding a dielectric. Similarly to the case where a dielectric is added to the ion diffusion preventing layer 16, even when it is made of only a synthetic resin, if the thickness is increased, the resistance value increases and the dielectric constant decreases. . In order to effectively prevent the ion diffusion, the film needs to be a uniform film, so that the thickness is practically about 0.1 to 10 μm. This configuration can be provided in a layer adjacent to the dielectric layer 14. When a colorless and transparent resin is used, it may be formed between the transparent electrode layer 12 and the light emitter layer 13.

These ion diffusion preventing layers 17 may be used in a single layer or in multiple layers depending on the purpose.
As a lamination method of each layer such as the decorative layer 11, the transparent electrode layer 12, the light emitting layer 13, the dielectric layer 14, the counter electrode layer 15, and the protective layer 16, for example, a transfer method, a spray method, gravure printing, and offset printing. , Screen printing, pad printing and the like.

  The EL sheet 5 before the shaping process obtained in this way is set in a concave mold that has been cut into a key top shape so that the base film 10 faces outward, and is formed by pressure forming, vacuum forming, press forming. The intermediate molded body of the illumination type push button switch member 1 is obtained by molding into a desired key top shape. Next, a thermoplastic or thermosetting, light, electron beam or reaction curable resin is injected into the recess on the back side of the key top and cured to obtain a finished product of the illuminated pushbutton switch member 1. In addition, you may employ | adopt the method of fitting and integrating the EL sheet 5 shape-processed by the core material 3 prepared beforehand.

[Example 1]

  A specific illuminated pushbutton switch member 1 was manufactured according to the above embodiment.

  A decorative film 11 was formed by screen-printing a colored ink (manufactured by Noriphan HTR / Prol) on a substrate alloy film made of polycarbonate having a thickness of 125 μm (manufactured by Byhole / Bayer). An adhesive layer (IPS000 / manufactured by Teikoku Ink Co., Ltd.) was screen-printed on the back of the decorative layer 11, and a conductive polymer (Orgacon P3040 / Agfa Inc.) was screen-printed thereon as the transparent electrode layer 12. Next, an auxiliary electrode layer (circuit) was screen-printed with silver paste (JEF-6022SS / manufactured by Japan Atchison Co., Ltd.) at a place other than the light emitting region on the transparent electrode layer 12. On the transparent electrode layer 12, a medium ink (JELCON AD-HM6 / manufactured by Jujo Chemical Co., Ltd.) was screen-printed as an adhesive layer. Thereafter, a phosphor ink (8155N EL medium / DuPont) was screen-printed at a place where light emission was necessary, and the phosphor layer 13 was formed. As the dielectric layer 14, 250 mass parts of barium titanate (BT100P / BT) having a dielectric constant of 250 parts by mass with respect to 100 parts by mass of fluororubber in a solvent obtained by dissolving fluororubber (Daiel G501 / manufactured by Daikin Industries, Ltd.) in methyl ethyl ketone. A dispersion of Fuji Titanium Industry Co., Ltd.) was screen printed. As the ion diffusion preventing layer 17, an EL carbon paste (7152 EL carbon paste / manufactured by DuPont) was used to form an ion diffusion preventing layer 17 having an average film thickness of 3 μm by screen printing. Further, a silver paste (JEF-6022SS / manufactured by Nippon Atsson Co., Ltd.) was screen-printed thereon as the counter electrode layer 15. Furthermore, as a protective layer, PC-based ink (manufactured by Noriphan HTR / Prol) was printed to obtain an EL sheet 5 before shaping.

  The obtained EL sheet 5 is set in a concave mold of a mold cut into a key shape so that the surface of the base film 10 is on the mold side, under conditions of a mold temperature of 120 ° C. and a molding time of 15 seconds. Press molding was performed.

  A polycarbonate resin (Iupilon / Mitsubishi Engineering Plastics Co., Ltd.) is injected into the key top portion 6 of the molded EL sheet 5 by injection molding to form the core material 3, and an illuminated pushbutton switch Member 1 was obtained.

When an alternating voltage was applied to the obtained illuminated pushbutton switch member 1 to emit light, the increase in the resistance value of the electrode due to the molding process was suppressed, so that the plurality of key top bodies 2 had almost uniform brightness. It was confirmed that light was emitted. An illuminated pushbutton switch member 1 was obtained. The initial luminance at the time of driving at a constant voltage power supply of 100 V and 400 Hz was 105 cd / m ² .

The obtained illuminated pushbutton switch member 1 is left in a high temperature and high humidity environment with a temperature of 60 ° C. and a humidity of 95% while being continuously driven to emit light at 100 V and 400 Hz using a constant voltage power source. When the change was observed, the occurrence of black spots was confirmed 576 hours after the start of continuous lighting. The illuminated pushbutton switch member 1 is generally required to have a durability of 240 hours or more under various environments, and thus was judged to satisfy the requirements sufficiently.
[Example 2]

  Example 2 was manufactured by the same configuration and the same manufacturing method as in Example 1 except for the ion diffusion preventing layer 17, and the same test as in Example 1 was performed.

In Example 2, a fluororubber (G501 / Daikin Chemical Industry Co., Ltd.) dissolved in methyl ethyl ketone was used as a solvent, and 50 parts by mass of titanium oxide having a dielectric constant of 100 was dispersed with respect to 100 parts by mass of the fluororubber. The thing was screen-printed and the ion diffusion prevention layer 17 with an average film thickness of 3 micrometers was provided.
[Example 3]

  Example 3 was manufactured by the same configuration and the same manufacturing method as in Example 1 except for the ion diffusion preventing layer 17, and the same test as in Example 1 was performed.

In Example 3, a solution prepared by dissolving fluororubber (G501 / Daikin Chemical Industry Co., Ltd.) in methyl ethyl ketone was used as a solvent, and fluororubber was dispersed in 50 parts by weight of titanium oxide with respect to 100 parts by weight as a screen. Printing was performed, and a first ion diffusion prevention layer having an average film thickness of 3 μm was provided. Furthermore, a second ion diffusion preventing layer having an average film thickness of 3 μm was provided by screen printing using carbon paste (7152 EL carbon paste / manufactured by DuPont).
[Example 4]

  Example 4 was manufactured by the same configuration and the same manufacturing method as in Example 1 except for the ion diffusion preventing layer 17, and the same test as in Example 1 was performed.

In Example 4, a fluororubber (G501 / Daikin Chemical Co., Ltd.) dissolved in methyl ethyl ketone was screen-printed to provide an ion diffusion prevention layer having an average film thickness of 3 μm.
[Comparative Example 1]

  Comparative Example 1 was manufactured with the same configuration and the same manufacturing method as in Example 1 except for the ion diffusion preventing layer 17, and the same test as in Example 1 was performed.

In Comparative Example 1, a layer having an average film thickness of 3 μm was formed by screen printing using the same material as the dielectric layer 14 instead of the ion diffusion preventing layer 17.
[Comparative Example 2]

  Comparative Example 2 was manufactured by the same configuration and the same manufacturing method as in Example 1 except for the ion diffusion preventing layer 17, and the same test as in Example 1 was performed.

  In Comparative Example 2, the illuminated pushbutton switch member 1 was manufactured without providing the ion diffusion preventing layer 17.

  A performance test was performed on Examples 1 to 4 and Comparative Examples 1 and 2 as described above under the same conditions described in Example 1. The results are shown in Table 1.

  That is, from the test results of Examples 1 to 4, it was confirmed that the black spot generation time tends to be shorter as the initial luminance is higher. However, in any case of Examples 1 to 4, generation of black spots is not confirmed within 240 hours after the start of continuous lighting, and a highly reliable illuminated pushbutton switch member is obtained even under high temperature and high humidity. It was. Based on such characteristics, it can be said that the material for the ion diffusion prevention layer may be appropriately selected in consideration of the use application of the product, molding elements such as the clearance / height of the product, restrictions on driving conditions, and the like.

  On the other hand, in the configuration in which the ion diffusion preventing layer of Comparative Examples 1 and 2 was not provided, the black spot was generated within 240 hours.

It is principal part sectional drawing which showed an example of the member for illumination type pushbutton switches which concerns on embodiment of this invention. It is principal part sectional drawing which showed the detail of the surface light-emitting body part of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 is an illumination type pushbutton switch member 2 is a key top main body 3 is a core material 4 is a surface light emitter part 5 is an EL sheet 6 is a key top part 10 is a base film 12 is a transparent electrode layer 13 is a light emitter layer 14 is a dielectric Body layer 15 is a counter electrode layer 17 is an ion diffusion prevention layer 18 is a top surface portion

Claims (3)

The transparent electrode layer of an EL sheet having a surface light emitter portion laminated in the order of a transparent electrode layer, a light emitter layer, a dielectric layer, and a counter electrode layer is disposed on the top surface side of the key top, In the illuminated pushbutton switch member having at least one or more key top portions raised from the planar portion of the EL sheet so as to cover the upper surface and side surfaces of the core material forming the three-dimensional shape, the transparent electrode layer A member for an illuminated pushbutton switch, wherein at least one ion diffusion prevention layer is provided between the electrode and the counter electrode layer. The ion diffusion preventing layer is obtained by dispersing a conductive filler mainly composed of nickel or carbon in a synthetic resin, and the ion diffusion preventing layer is provided in contact with the counter electrode layer. The member for an illuminated pushbutton switch according to claim 1. The ion diffusion prevention layer is obtained by dispersing a dielectric having a dielectric constant lower than that of the dielectric used for the dielectric layer in a synthetic resin, and the ion diffusion prevention layer is provided in contact with the dielectric layer. The illumination type push button switch member according to claim 1, wherein the illumination type push button switch member is provided.

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