JP2005190893A - Member for illumination-type push button switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member for an illumination-type push button switch with a built-in EL element stably generating brightness almost as designed. <P>SOLUTION: A conductive repair circuit is additionally formed at the part where crack is generated during a molding process. Preferably, the repair circuit is formed by carbon black or graphite. The repair circuit is an area between adjacent key-top parts 3, 3, of which the interval width W is smaller than the height of the key-top 3, which is formed so as to include the part where the electrode circuit is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a member for an illuminated pushbutton switch used for an illuminated pushbutton switch of 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, illuminated pushbutton switches are often used in input devices such as mobile communication devices and small electric / electronic devices. This type of input device is required to have a so-called illumination function for illuminating a display unit that exhibits the function of a push button switch when used at night.

  For example, in a pushbutton switch 30 used for an input device such as a cellular phone, as shown in FIG. 5, a cover base 32 and a circuit board 33, which are integrally formed with a plurality of key top portions 31 constituting operation keys. Are installed in the casing of the target input device, and the switch function of the push button switch 30 is realized. The push button switch 30 includes a display unit 34.

  On the circuit board 33, a light source such as an LED 35 is provided. The direct light emitted therefrom or the reflected light of this direct light is transmitted from the back surface portion of the key top portion 31 to the top surface portion. In this way, the key top portion 31 is bright even at night, and a mobile phone or the like can be used without any trouble.

  The present applicant has previously applied for a patent on a pushbutton switch member that can realize illumination of a display portion without unevenness in luminance while suppressing power consumption, and is thin and light, and a manufacturing method thereof. (Patent Document 1).

Such a member for a push button switch is a member that constitutes a part of the push button switch, and is formed by drawing an EL sheet. This EL sheet contains an EL element. The EL element in the EL sheet uses a carbon electrode or a silver film electrode as a counter electrode.
JP 2002-367469 A

  In the case of a pushbutton switch member obtained by drawing an EL sheet, there is a problem in that there are variations in the luminance of the EL element, and it is often much lower than the expected value.

  Accordingly, an object of the present invention is to provide an illumination type push button switch member with a built-in EL element that stably emits luminance substantially as designed.

  In order to solve the above-mentioned problems, the present inventor has conducted extensive studies and researches, and as a result, has found that fine cracks are present in the electrode layer circuit in the EL sheet laminate upon drawing. That is, the present inventors have found that this crack further weakens the weak supply power necessary for EL emission, and often hinders the stability of luminance. As a result of further detailed investigation, it was found that the cracks occurred mainly in the places where the distance between the adjacent push buttons was smaller than the height value of the push buttons.

  Therefore, the present inventor has taken the following means in order to solve the above problems.

  In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an illumination type push button switch member including an EL element, in an electrode layer circuit that is electrically connected to the EL element, in a crack portion generated during molding. A conductive repair circuit is formed in an overlapping manner.

  The invention according to claim 2 is the invention according to claim 1, wherein the transparent electrode layer in the EL element is formed of a conductive polymer.

  According to a third aspect of the invention, in addition to the invention of the first or second aspect, the repair circuit is formed of a material substantially the same as the material forming the counter electrode or auxiliary electrode of the EL element. It is.

  According to a fourth aspect of the present invention, in addition to the first aspect of the present invention, the repair circuit is made of carbon black or graphite.

  According to a fifth aspect of the invention, in addition to the invention according to any of the first to fourth aspects, the repair circuit is a region between adjacent key top portions, and the interval width value thereof is It is smaller than the height value of the key top part, and is formed including the part where the electrode layer circuit is laid.

  According to a sixth aspect of the present invention, in addition to the first aspect of the present invention, the electrode layer circuit is a counter electrode layer circuit and / or an auxiliary electrode layer circuit.

  In the first aspect of the invention, the repair circuit compensates for the conductivity of the region where the electric resistance is high.

  In the invention described in claim 2, the transparent electrode layer is formed of a conductive polymer. Since conductive polymers are generally excellent in moldability, cracks are less likely to occur during molding. What is necessary is to consider cracks substantially for the auxiliary electrode layer circuit or the counter electrode layer circuit.

  In the invention according to claim 3, the material on which the counter electrode or the auxiliary electrode is formed can be used.

  In the invention according to claim 4, the repair circuit is formed of a material effective for suppressing ionization.

  The invention according to claim 5 is appropriately repaired at a place where repair is necessary.

  According to the first to fifth aspects of the present invention, since the repair circuit is formed at the crack portion, it is possible to provide an illumination-type pushbutton switch member with a built-in EL element that stably emits luminance almost as designed. it can.

  According to the second aspect of the invention, since the transparent electrode layer is a highly flexible material, it is only necessary to substantially repair the counter electrode layer circuit and / or the auxiliary electrode layer circuit.

  According to the invention described in claim 3, since the material on which the counter electrode or the auxiliary electrode is formed can be used, the selection of the material is easy and the economy is high.

  The invention according to claim 4 has the same effect as that of claim 3 if the material of the repair circuit is the same as the material on which the counter electrode is formed. Even if it is different from the material of the counter electrode and the auxiliary electrode, carbon is excellent in suppression of ionization and stability, can suppress deterioration of the phosphor, and as a result, the light emission is stabilized.

  In the invention according to the fifth aspect, the repair is reasonably economically performed at a place where the repair is necessary.

  FIG. 1 is a cross-sectional view of a principal part showing an illumination type push button switch member according to the best embodiment of the present invention. A part of the cross section of the top surface in FIG. 1 is circled, and FIG. 2 shows an enlarged view.

  The illuminated pushbutton switch member 1 according to the embodiment shown in FIG. 1 is provided with a display portion 2 displaying characters, symbols, symbols, etc. on the top surface side of the key top portions 3a, 3b. At least the display unit 2 is provided with a light emitting layer 11 constituting an EL element. A presser 5 is provided at the lower ends of the key top portions 3a and 3b to press the movable contact.

  The material of the core material 6 of the key top portions 3a and 3b is selected from a hard or soft resin, an elastomer, or the like. In the key top portions 3a and 3b, the core material 6 is covered with a laminate.

  The laminated body covering the core material 6 is provided with an outermost peripheral portion with a transparent insulating film 7. Examples of the material of the transparent insulating film 7 on the outermost peripheral surface portion include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyacryl, polystyrene, polyimide, polyamide, polyphenyl sulfite and the like. Thermoplastic elastomers may be used. For example, styrene-based, polyester-based, and polyamide-based thermoplastic elastomers can be used. These copolymers and modified products such as alloys can be used. These may be used alone or in combination. The thickness is generally 10 to 500 μm.

  The top surface portions of the key top portions 3 a and 3 b are provided with an opaque colored layer 8 having light shielding properties and insulating properties on the back surface of the transparent insulating film 7. The opaque coloring layer 8 is provided with a punching die portion 9 adapted to the form of characters, symbols, designs, etc. of the display portion 2. The punching die part 9 is in a part of the top surface part of the key top parts 3a, 3b, and thereby forms a negative pattern made up of characters, symbols, designs, etc., but is not limited thereto. Specifically, the opaque colored layer 8 is used to form a blank character, and if necessary, a transparent colored layer is added to the blank character, and the opaque colored layer 8 is used to form a character, and if necessary, a transparent colored layer is used. A configuration such as backing may be used.

  On the back surface of the opaque colored layer 8, a transparent electrode layer 10 serving as one electrode of the EL element 4 is provided. In addition, the transparent electrode layer 10 is buried also inside the punching die part 9, thereby forming a positive pattern. The transparent electrode layer 10 is made of, for example, a conductive polymer. In particular, a highly conductive polypyrrole, polythiophene or polyaniline derivative having transparency is preferable. The transparent electrode layer 10 may be provided with an auxiliary electrode layer circuit having higher conductivity than that of the conductive polymer so as to be electrically connected thereto.

  The light emitting layer 11 is obtained 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, and an acrylic resin copolymer. They may be used alone or in combination. A material with a dielectric constant as high as possible should be selected. High brightness can be easily obtained with a material having a high dielectric constant.

  A dielectric layer 12 is provided on the back side of the light emitting layer 11. For example, high dielectric substance powder such as barium titanate and potassium titanate is dispersed in the dielectric layer 12 in a binder similar to the above. When such a high dielectric material is disposed, the electrolytic efficiency may be improved.

  A counter electrode layer 13 that forms the other electrode of the EL element 4 is provided on the back surface of the dielectric layer 12. The counter electrode layer 13 is formed of a conductive paint in which a conductive dispersoid is dispersed in a dispersion medium (binder). As the dispersion medium, polyester-based, acrylic-based, urethane-based, silicone-based, epoxy-based, rubber-based resin, or a copolymer thereof is used. They may be used alone or in combination. As the conductive dispersoid, a metal or alloy such as gold, silver, copper, or nickel, or a conductive filler such as carbon black or graphite is used. They may be used alone or in combination.

  The transparent electrode layer 10, the light emitting layer 11, the dielectric layer 12, and the counter electrode layer 13 constitute the EL element 4. The display portion 2 is formed by the EL element 4 and the opaque colored layer 8. The display unit 2 including the EL element 4 is on the top surface, and this forms an EL sheet.

  An adhesive layer 14 is interposed between the back surface of the counter electrode layer 13, that is, the core material 6. A part of the cross section of the top surface in FIG. 1 is circled, and is shown in an enlarged manner in FIG.

  FIG. 3 is an enlarged view of a cross section of a region surrounded by a circle in FIG. 1, that is, a region between adjacent key top portions 3a and 3b.

  As shown in FIG. 3, in the region between the key top portion 3a and the key top portion 3b, a region in which the transparent insulating film 7, the opaque colored layer 8, and the counter electrode layer circuit 13a are laminated in this order. There is. Note that there is a region in which the transparent insulating film 7, the opaque colored layer 8, and the auxiliary electrode layer circuit are laminated in this order instead of the counter electrode layer circuit 13a. At locations where the counter electrode layer circuit 13a is provided, cracks often occur in the counter electrode layer circuit 13a as shown in FIG. Alternatively, the auxiliary electrode layer circuit of the transparent electrode layer 10 is cracked. In particular, cracks are likely to occur when a carbon-based conductive material that is weak against pulling is used. In the present embodiment, a repair circuit 21 is provided at such a crack location 20. As a result, the repair circuit 21 is formed redundantly at the location where the counter electrode layer circuit 13a is provided. An insulating material layer 22 is provided on the back side of the repair circuit 21. FIG. 4 is a cross-sectional view taken along the line AA through the repair circuit 21 in FIG.

  The crack location 20 is an area between the adjacent key top portions 3a and 3b, and is likely to occur at a location where the interval width value (key pitch) W is smaller than the height value h of the key top portion. The repair circuit 21 is formed at such a location, for example.

  The repair circuit 21 is formed of, for example, the same type of conductive material as the conductive material forming the counter electrode layer 13. Alternatively, the conductive material forming the auxiliary electrode layer circuit is substantially formed of the same kind of conductive material, for example. Specifically, it is formed of a single metal such as gold, silver, copper nickel, or an alloy containing these metals, or a conductive filler such as carbon black or graphite. They may be used alone or in combination. Carbon black, graphite, and the like are particularly preferable because of high conductivity.

  Here, in addition to the case where the same type is substantially the same, for example, a silver paste or a conductive polymer, which is a formable conductive material, is used for the counter electrode layer 13, and the auxiliary electrode layer circuit is the same. This means that even if the material is different, the material is the same in terms of the conductive material, such as using a conductive polymer or carbon black which is a conductive material. However, combinations that corrode or denature each other are not included.

  The illuminated pushbutton switch member 1 as described above is manufactured, for example, as follows.

  With the transparent insulating film 7 at the bottom, the opaque colored layer 8 is formed on the transparent insulating film 7 by negative printing. At this time, the pattern part of the display part 2 displaying the switch function is cut out at the place where the top surface part of the key top part 3 is located, and the die part 9 is formed. In negative printing with the transparent colored layer 8, opaque colored ink having light shielding properties and insulating properties is used.

  A transparent electrode layer 10 is formed on the opaque colored layer 8. The material for forming the transparent electrode layer 10 is also filled in the die part 9. An auxiliary electrode layer circuit leading to the transparent electrode layer 10 is also formed.

  A light emitting layer 11 is formed on the transparent electrode layer 10. The light emitting layer 11 may be printed only on the top surface portions of the key top portions 3a and 3b. The light-emitting layer 11 is wet-coated with inorganic phosphor powder such as zinc sulfide dispersed in a binder.

  A dielectric layer 12 is provided on the light emitting layer 11. The dielectric layer 12 is applied by dispersing a high dielectric material in a binder. A counter electrode layer 13 is provided on the dielectric layer 12, and a counter electrode layer circuit 13a is further formed. The counter electrode layer 13 and the counter electrode layer circuit 13a are made continuous. In this way, an EL sheet before shaping is obtained. An adhesive layer 14 may be formed in advance on the EL sheet before the shaping process in a range where it adheres to the core material.

  Examples of the method for laminating each layer include a transfer method, spraying, screen printing, pad printing, ink jet printing, and potting.

  The EL sheet before the shaping process obtained in this way is set in a die having an uneven shape, and is drawn to match the shape of the desired key top portion 3 by compressed air / vacuum molding, press molding or the like. Do. A precursor of the illuminated pushbutton switch member 1 is obtained in which a convex portion protrudes from the back side on the counter electrode layer 13 side to the front side where the transparent electrode layer 10 is close. The core material 6 may be formed by injecting a thermoplastic or thermosetting resin, light, electron beam or reaction curable resin and curing it in the mold.

  In the drawing process, the electrode circuit portion where the resistance value is increased by being stretched together with the film is specified, and the repair circuit 21 is formed with conductive material including such a portion in an overlapping manner. . The repair circuit 21 including the portion where the counter electrode layer circuit 13a or the auxiliary electrode layer circuit is formed at the location where the height value h of the key top portion 3 exceeds the interval width value W between the key tops, that is, the key pitch. Overlapping.

  Examples of the method for forming the repair circuit 21 include screen printing, spraying and potting. Needless to say, the accuracy of pattern formation can be improved by setting the jig in a key top shape.

  The repair circuit 21 formed in an overlapping manner is overlaid with an insulating layer 22, thereby preventing an unexpected short circuit when a push button switch is formed.

  The repair circuit 21 may be formed before the core resin injection after the drawing process. It is preferable to provide the insulating layer 22 after the repair circuit 21 is formed. The insulating layer 22 is formed by wet or thermal spraying. Examples of the material for forming the insulating layer 22 include polyester-based, acrylic-based resins, synthetic rubber-based, polycarbonate-based, and silicone-based resins. They may be used alone or in combination.

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

  A 125 μm polycarbonate alloy film (byhole / manufactured by Bayer) was used as the transparent insulating film 7, and a colored ink was screen-printed thereon and applied. On this film, a conductive polymer (Orgacon P3040 / Agfa) was screen printed as the transparent electrode layer 10. Further, an adhesive layer 10a of the transparent electrode layer 10 (JELCON AD-HM6 / manufactured by Jujo Chemical Co., Ltd.) was applied to the transparent electrode layer 10 by screen printing. Thereafter, phosphor ink (8155N EL medium / DuPont) was screen printed at a place where light emission was necessary to form the light emitting layer 11.

  The dielectric layer 12 was formed by applying an insulator paste (8153N EL insulator paste / manufactured by DuPont) to which barium titanate was added. As the counter electrode layer 13 and the counter electrode layer circuit 13a, a conductive paste (7152 EL carbon paste / manufactured by DuPont) was used and printed in the same manner to obtain a laminate sheet.

  In the laminate film, an adhesive layer 14 was further formed in a range in contact with the core material 6 resin. The adhesive layer 14 was printed with a PC-based ink (Noriphan HTR / Prowl).

  This printing film on which the PC-based ink was printed, that is, the EL sheet before the shaping process, was set in a mold having an uneven shape with a mold temperature of 120 ° C. and subjected to a drawing process.

  PC resin was injected into the recess by injection molding of PC resin to the drawn film, and a precursor of the illumination type push button switch member 1 was obtained.

  The molded precursor is set in a jig having a key-shaped depression, and is formed on the counter electrode layer 13 at a location where a crack is present in a region between the adjacent key top portion 3a and the key top portion 3b. A conductive ink (7152 EL carbon paste / DuPont) was potted. In this way, the repair circuit 22 was formed, and the illuminated pushbutton switch member 1 was obtained.

  An insulating material (Bellegan Z Spray: manufactured by Toray Dow Corning Silicone Co., Ltd.) was sprayed on the back surface of the resulting illuminated pushbutton switch member 1.

  The illumination pushbutton switch member 1 was obtained in which the increase in the resistance value of the electrode due to the drawing process was suppressed and the luminance was improved.

  According to this illuminated pushbutton switch member 1, it is possible to prevent electrode conduction failure, resistance value increase, and the like due to drawing. A push button switch with high brightness and high reliability can be obtained with high yield.

It is principal part sectional drawing which showed an example of the member for illumination type pushbutton switches concerning the best embodiment. It is an enlarged view of the cross section of the top | upper surface part of the member for illumination type pushbutton switches. FIG. 2 is an enlarged view of a cross section of a portion surrounded by a circle in FIG. 1, that is, a region between adjacent key top portions. It is an AA line sectional view which penetrates a repair circuit. It is sectional drawing which shows an example of the conventional pushbutton switch.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illuminated type pushbutton switch member 2 Display part 3 Key top part 4 EL element 5 Movable contact 6 Core material 7 Transparent insulating film 8 Opaque colored layer 9 Die mold part 10 Transparent electrode layer 11 Light emitting layer 12 Dielectric layer 13 Counter electrode layer 13a Counter electrode layer circuit 14 Adhesive layer 20 Crack location 21 Repair circuit 22 Insulating material layer

Claims (5)

An illumination type push button switch member including an EL element is characterized in that a conductive repair circuit is formed redundantly in a crack portion generated during molding in an electrode layer circuit conducting to the EL element. Illuminated pushbutton switch member. 2. The illuminated pushbutton switch member according to claim 1, wherein the transparent electrode layer in the EL element is formed of a conductive polymer. 3. The illuminated pushbutton switch member according to claim 1, wherein the repair circuit is formed of a material that is substantially the same type as a material that forms the counter electrode of the EL element. 3. The illuminated pushbutton switch member according to claim 1, wherein the repair circuit is made of carbon black or graphite. The repair circuit is a region between adjacent key top portions, the interval width value of which is smaller than the height value of the key top portion, and includes a portion where the electrode layer circuit is laid. 5. The illuminated pushbutton switch member according to any one of claims 1 to 4.

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