JP2009224214A - Portable electronic apparatus, and shading adhesive sheet - Google Patents

Abstract

Provided is a portable electronic device in which an entire operation key can be designed to have transparency, and only a part of the operation key can be brightly illuminated, and the overall thickness can be reduced. .
An operation key 4 that is substantially transparent and has an illuminated marking portion 4a to be illuminated, a light source for irradiating the operation key 4 with light from below, and a space between the operation key 4 and the light source. In a portable electronic device provided with a keypad 2a disposed on the keypad 2a, a translucent portion that is affixed to the surface of the keypad 2a on the operation key 4 side and that corresponds to the illuminated marking portion 4a of the operation key 4 A portable electronic device, further comprising a light-shielding pressure-sensitive adhesive sheet 6 having a light-shielding pressure-sensitive adhesive sheet 6 positioned below the operation key 4.
[Selection] Figure 1

Description

  The present invention relates to a portable electronic device such as a mobile phone or a portable game device, and a light-shielding pressure-sensitive adhesive sheet used for the portable electronic device, and more specifically, an operation key of the portable electronic device. The present invention relates to a portable electronic device that can illuminate only a portion and a light-shielding pressure-sensitive adhesive sheet for the portable electronic device.

  Conventionally, in a portable electronic device such as a cellular phone, the entire operation key is illuminated or a part of the operation key is illuminated in order to improve design and operability.

  For example, Patent Document 1 below shows a mobile phone shown in an exploded perspective view in FIG. In this mobile phone, a transparent wiring substrate 101 is disposed on a plurality of light sources (not shown) located below. On the transparent wiring substrate 102, a plurality of metal domes 101a and metal domes 104b corresponding to the illuminated portion 104a are formed. On the wiring substrate 101, a key base 102 made of a flexible elastic material is laminated. A light shielding plate 103 made of a metal such as stainless steel is laminated on the key base 102, and a circular operation key 104 and a plurality of rectangular keypads 105 are arranged on the light shielding plate 103.

  In the light shielding plate 103, a cross-shaped opening 103 a is formed in a portion located below the operation key 104. The illuminated portion 104a is located above the cross-shaped opening 103a.

  In the circular operation key 104, only the four small circular illuminated parts 104a are translucent, so that only the illuminated part 104a is illuminated by light from below, and other operation keys 104 The part is not illuminated. That is, light from below passes through the cross-shaped opening 103a, is guided to the illuminated portion 104a of the upper operation key 104, and only the illuminated portion 104a is illuminated.

  Therefore, it is possible to illuminate only the illuminated portion 104 a that is a part of the operation key 104. However, in such a configuration, the design of the entire operation key 104 cannot be made shining, and the designability cannot be improved.

  Further, since the light shielding plate 103 made of a metal such as stainless steel is used, the pressing force when the illuminated portion 104 a of the operation key 104 is pressed with a finger is applied to the keypad 102 a located below the light shielding plate 103. There was also a problem that it was difficult to reach the top surface. In addition, since the metal light shielding plate 103 is used, it is difficult to reduce the thickness.

  On the other hand, the following patent document 2 discloses an illuminated key 121 shown in FIG. The illuminated key 121 has a key top 122. The key top 122 is made of a transparent synthetic resin. Accordingly, light guided from below passes through and reaches the upper surface 122 a of the key top 122.

  However, the light shielding film 123 is laminated on the upper surface 122 a of the key top 122. A part of the light shielding film 123 is removed by a laser, and a marking 124 is formed. That is, the marking 124 is an opening corresponding to an appropriate character or picture, and a region outside the opening is covered with the light shielding film 123. Accordingly, it is possible to obtain the key top 122 in which the marking 124 is illuminated by the light guided from below.

  However, with the configuration described in Patent Document 2, the entire key top 121 cannot be a transparent member. That is, the entire operation key is transparent and cannot be illuminated.

Further, in order to form the marking 124, complicated processing using a laser or the like must be performed, and the manufacturing process is complicated.
JP 2007-294246 A Japanese Patent Application Laid-Open No. 11-66997

  In the present invention, in view of the above-described state of the prior art, the entire operation key can be designed to be transparent and illuminated, and only a part of the operation key exhibits a stronger and / or different color. It is another object of the present invention to provide a light-shielding pressure-sensitive adhesive sheet that can be illuminated in the manner described above, and to make it possible to reduce the overall thickness of the sheet, and an electronic device using the same.

  A more limited object of the present invention is to not only illuminate only a part of the operation keys so as to exhibit a strong and / or different color, but the outer shape of the light-shielding pressure-sensitive adhesive sheet below the operation keys through the operation keys. An object of the present invention is to provide a portable electronic device that is difficult to see and a light-shielding pressure-sensitive adhesive sheet for the portable electronic device.

  The light-shielding pressure-sensitive adhesive sheet for portable electronic devices according to the present invention includes a black layer, a first white layer formed on one surface of the black layer, and a second white layer formed on the other surface of the black layer; It is a light shielding adhesive sheet which is a laminated sheet having

  Even if the entire operation key is substantially transparent, the outer shape of the light-shielding pressure-sensitive adhesive sheet portion located below the operation key is difficult to understand. That is, when the periphery of the operation key has a white frosted tint, the color difference from the white layer is reduced, so that the outer edge of the keypad below the operation key is difficult to see. Therefore, it is possible to obtain a portable electronic device that is further excellent in design. In this case, the first or second white layer itself may have adhesiveness, or a further transparent adhesive layer may be laminated on the laminated sheet.

  According to the present invention, the operation key which is substantially transparent and has an illuminated marking portion to be illuminated, a light source for irradiating the operation key with light from below, and disposed between the operation key and the light source In a portable electronic device comprising a keypad on which a part of the operation key is operated, the electronic key is attached to a surface of the keypad on the operation key side, and is applied to an illuminated marking portion of the operation key. A portable electronic device is provided, further comprising a light-blocking pressure-sensitive adhesive sheet having a corresponding light-transmitting portion, wherein at least a part of an outer edge of the light-blocking pressure-sensitive adhesive sheet is located below the operation key Is done.

  In the present specification, “a light source that emits light from below” does not necessarily include a light source directly below the center of the operation key. Even when light is emitted from a sidelight type light source, if there is a light source below the operation key, it is “a light source that emits light from below”.

  On the specific situation with the portable electronic device which concerns on this invention, the said light-shielding adhesive sheet is laminated | stacked on the other surface of the black layer, the 1st white layer laminated | stacked on the one surface of the black layer, and the said black layer. A laminated sheet having a second white layer. In this case, since the upper surface of the light-shielding pressure-sensitive adhesive sheet is the first white layer or the second white layer, the color difference from the substantially transparent operation key is reduced. Therefore, it becomes difficult to understand the outer shape of the adhesive sheet positioned below the operation keys. Therefore, even if it is a case where the area of a light-shielding adhesive sheet is made small, designability is hard to be impaired.

  In addition, in the laminated sheet, since the white layer is laminated on both surfaces of the black layer, light from below can be reliably blocked except for the light transmitting portion.

  In another specific aspect of the portable electronic device of the present invention, a pressure-sensitive adhesive layer provided on one side of the laminated sheet is further provided. In the present invention, in the light-shielding pressure-sensitive adhesive sheet, the first or second white layer itself may have adhesiveness. In that case, an adhesive may be contained in the first or second white layer. Or in this invention, as mentioned above, the adhesive layer may further be provided in the single side | surface of the lamination sheet.

  The light-shielding pressure-sensitive adhesive sheet for portable electronic devices according to the present invention includes a black layer, a first white layer formed on one surface of the black layer, and a second white layer formed on the other surface of the black layer; Therefore, the black layer can sufficiently shield light, and the white layers on both sides can effectively use light and make the translucent part stand out.

  When the operation key is a touch sensor key, the operation key can be easily operated without impairing the appearance. For example, in a light-shielding sheet having only a black layer, the color of the key is deteriorated, and the key portion is difficult to understand and difficult to operate.

  In addition, when the operation key uses a light sensor, the light-shielding pressure-sensitive adhesive sheet according to the present invention can effectively guide light from the light source to the light-transmitting part while reliably shielding light other than the sensor part. It is easy to operate and can prevent malfunction.

  In the portable electronic device using the light-shielding sheet of the present invention, the light-shielding pressure-sensitive adhesive sheet of the present invention is attached to the operation key side surface of the keypad disposed between the operation key and the light source. In the part covered with the light-shielding pressure-sensitive adhesive sheet, only the light-transmitting part of the light-shielding pressure-sensitive adhesive sheet passes through, and only the illuminated marking part is illuminated by the light from the light source. The illuminated marking portion of the operation key is defined by the light transmitting portion of the light-shielding pressure-sensitive adhesive sheet, and the operation key itself can be made transparent as a whole. Therefore, it is possible to provide a portable electronic device having an operation key with excellent design, in which only a part of the operation key that is substantially transparent as a whole is illuminated.

  In addition, when the light-shielding pressure-sensitive adhesive sheet is not located in the entire area below the operation key, light from the light source reaches the operation key in a portion outside the light-shielding pressure-sensitive adhesive sheet, and the entire operation key is illuminated. . In this case, since the light from the light source circulates from the surroundings above the light-shielding pressure-sensitive adhesive sheet, the illuminated marking portion is relatively strongly illuminated by the light from the light source in the upper part of the light-shielding pressure-sensitive adhesive sheet. become. Alternatively, if a translucent adhesive sheet or the like is attached to the illuminated marking portion, the illuminated marking portion can be illuminated so as to exhibit a different color from other portions.

  In addition, since a light shielding plate made of a stainless steel plate or the like is not required, when the operation key is a key that is operated by pressing, the pressing force from the operation key is smoothly transmitted to the keypad. Therefore, the pressing force necessary for the operation can be reduced, and the operability can be improved.

  Furthermore, as described above, when only the illuminated marking portion of the operation key is illuminated, it is only necessary to affix the light-shielding adhesive sheet to the operation key side surface of the keypad. Since it is only necessary to attach a light-shielding pressure-sensitive adhesive sheet having a small area to the keypad, the area of the light-shielding pressure-sensitive adhesive sheet can be reduced. Therefore, the amount of the adhesive used can be reduced, and the environmental burden can be reduced. Moreover, problems such as odor and malfunction caused by volatile components such as a solvent and residual monomer contained in the pressure-sensitive adhesive, and discoloration of peripheral members can be suppressed.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1A is a schematic exploded perspective view of a mobile phone as a portable electronic device according to an embodiment of the present invention, and FIG. 2 is a schematic plan view showing a main part of the mobile phone of this embodiment. FIG. In the mobile phone according to the present embodiment, a key base 2 made of a transparent elastic material is laminated on a transparent wiring substrate 1. A circular operation key 4 and a plurality of operation keys 4 are arranged on the key base 2. The rectangular key tops 5 are stacked. Here, the circular operation key 4 has a plurality of illuminated marking portions 4a arranged in a distributed manner at positions equally divided into four in the circumferential direction of the circular operation key 4. The illuminated marking portion 4a is not particularly limited, but has a circular shape. In the present embodiment, the entire operation key 4 is white and translucent. Moreover, the translucent coloring sheet | seat 7 is affixed on the illuminated marking part 4a.

  The wiring board 1 has a plurality of metal domes 1a having relatively small diameters. The plurality of metal domes 1a are located below the operation keys 4, and one metal dome 1a is disposed below one illuminated marking portion 4a.

  A pair of metal domes 1b having a relatively large diameter are formed on both sides of the portion where the plurality of metal domes 1a are provided. A plurality of metal domes 1c having relatively large diameters are arranged on the sides of the portions where the metal domes 1a and 1b are provided. When these metal domes 1a to 1c are all pressed, the metal domes 1a to 1c are recessed so that the central portion protrudes downward, thereby electrically connecting a pair of conductors in which the lower electrical wiring is disposed below.

  Further, the entire wiring board 1 is transparent as described above. Accordingly, the light from the light source disposed below the wiring board 1 is guided upward. The light from the light source passes through the wiring board 1, passes through the transparent keypad, and is guided upward. As this light source, a suitable light source such as an LED can be used. In the portion where the operation key 4 is provided, a light source for irradiating light from below is disposed in a region where the operation key 4 is provided. Moreover, when illuminating the other key tops 5 etc., a light source is arrange | positioned below, respectively. Here, the key base 2 having a planar shape matching the rectangular area A is laminated.

  In the key base 2, a cross-shaped keypad 2a, a pair of rectangular keypads 2b, and a plurality of relatively small rectangular keypads 2c are integrally provided on a rectangular sheet made of a transparent elastic material. It has been. These keypads 2a to 2c are formed so that a part thereof is raised from the upper surface of a sheet made of a transparent elastic material. Therefore, the keypads 2a to 2c are formed so as to be able to bend downward due to pressure from above. By this bending, the metal dome 1a, 1b or 1c below the keypad is dented, and the lower portions of the metal domes 1a to 1c are turned on, and turned on.

  The feature of this embodiment is that a light-blocking pressure-sensitive adhesive sheet 6 having the same planar shape as that of the cross-shaped keypad 2a is attached to the upper surface of the cross-shaped keypad 2a. The light-shielding pressure-sensitive adhesive sheet 6 has a plurality of light-transmitting portions 6a through which light from below is transmitted. The translucent portion 6a is provided at a position overlapping the upper illuminated marking portion 4a. The light-shielding pressure-sensitive adhesive sheet 6 blocks light irradiated from below at portions other than the light-transmitting portion 6a. The light-shielding pressure-sensitive adhesive sheet 6 is formed of an appropriate light-shielding material as long as the light irradiated from below is blocked.

  However, in order to affix the light-shielding pressure-sensitive adhesive sheet 6 on the cross-shaped keypad 2a, as shown in FIG. 1 (b), the light-shielding pressure-sensitive adhesive sheet 6 is provided on the lower surfaces of the base material 6b and the base material 6b. And the formed pressure-sensitive adhesive layer 6c. And the said translucent part 6a is provided by forming a through-hole. But you may provide the translucent part 6a by making a part of base material 6b and the adhesive layer 6c transparent.

  Preferably, as shown in FIG. 3, the base material of the light-shielding pressure-sensitive adhesive sheet 6 includes a black layer 11, a first white layer 12 formed on one side of the black layer 11, and a second layer formed on the other side. A laminated sheet having a white layer 13 is used.

(Black layer)
The black layer 11 imparts light shielding properties to the light shielding adhesive sheet 6. Since the light-shielding pressure-sensitive adhesive sheet has the black layer 11, it has light-shielding properties.

  The black layer 11 is not particularly limited as long as it is configured to have black. The black layer 11 is preferably formed of black ink. The black layer 11 is preferably formed by applying black ink and drying it.

  The black ink preferably contains a black colorant as a light shielding material, a binder, and a solvent.

  The black colorant is not particularly limited, and examples thereof include carbon black, acetylene black, pine smoke, and graphite. Of these, carbon black is preferable.

  The average particle diameter of the black colorant is preferably 0.01 to 0.5 μm. If the average particle size of the black colorant is too small, the handleability may be reduced during the production of the black ink. If it is too large, the surface roughness of the black layer becomes too large and is laminated on the black layer and the black layer. Adhesion with the applied layer may be reduced. The average particle diameter of the black colorant means a calculated average diameter obtained by observing with an electron microscope.

  It does not specifically limit as a binder used for the said black ink, The binder currently used for the ink etc. can be used. Examples of such a binder include polyurethane resins, phenol resins, epoxy resins, urea melamine resins, and polymethyl methacrylate.

  It is preferable that the binder used for the black ink does not contain a halogen element such as chlorine, bromine, fluorine or iodine. When the binder contains a halogen element, the content of the halogen element is preferably 50 ppm or less. If a halogen element is contained in a large amount, when a liquid crystal display module unit using a light-shielding pressure-sensitive adhesive sheet is used, the display performance may deteriorate due to the generation of gas due to the halogen element. When the adhesive sheet is incinerated, harmful gases are generated and the environmental load may increase.

  The amount of halogen element contained in the binder can be measured by emission spectroscopic analysis. The emission spectroscopic analysis method is a measurement method for specifying contained elements by exciting atoms with a plasma light source to emit light and spectrally radiating light with a diffraction grating to obtain a so-called atomic spectrum. When measuring the amount of halogen element, for example, a trade name “PDA series” which is a measuring device commercially available from Shimadzu Corporation can be used.

  The solvent used for the black ink is appropriately selected and used according to the types of the black colorant and the binder.

  The black colorant is preferably contained in a proportion of less than 12% by weight in 100% by weight of the black ink. When there are too many black colorants, in an electronic device using a light-shielding pressure-sensitive adhesive sheet, electrical insulation properties may be lowered. The black colorant is preferably contained in a proportion of 5% by weight or more in 100% by weight of the black ink. If the amount of the black colorant is too small, sufficient light shielding properties may not be obtained.

  Examples of commercial products of the black ink include trade names “NB-500 black” and “cassette conch” manufactured by Dainichi Seika Co., Ltd.

  The thickness of the black layer 11 is preferably less than 15 μm, and more preferably 10 μm or less. If the black layer 11 is too thick, the light-shielding pressure-sensitive adhesive sheet may be too thick. The thickness of the black layer 11 is preferably 5 μm or more. If the black layer 11 is too thin, sufficient light shielding properties may not be obtained.

(White layer)
In the light-shielding pressure-sensitive adhesive sheet, the first and second white layers 12 and 13 are disposed on the surfaces on both sides of the base sheet. Therefore, the light-shielding pressure-sensitive adhesive sheet has light reflectivity on both sides. Moreover, in order to obtain light reflectivity, the light-shielding pressure-sensitive adhesive sheet can be attached from either side.

  The first and second white layers 12 and 13 are not particularly limited as long as they are configured to have white. The first and second white layers 12 and 13 are preferably formed of white ink or a white resin film. The first and second white layers 12 and 13 are preferably formed by applying white ink and drying, or formed by a white resin film.

  The first white layer 12 and the second white layer 13 may be formed of the same material, or may be formed of different materials. Especially, it is preferable to make one white layer into a white resin film and make the other white layer into white ink from a viewpoint of coexistence of an optical characteristic and thickness reduction. More preferably, it is preferable to provide a white layer composed of a white resin film and a white ink layer and a white ink layer composed of a white ink, since it is possible to further improve the balance between thinning and optical characteristics.

  The white resin film is preferably a resin film containing titanium oxide particles. A resin film containing titanium oxide particles is preferable because it exhibits a white color and is excellent in light reflectivity and strength.

  The resin material of the resin film is not particularly limited, and examples thereof include a polyvinyl chloride film, a polypropylene film, a polyethylene film, a polyester film, a polycarbonate film, a polyimide film, a polystyrene film, and cellophane, and a polyester film and a polypropylene film. Is preferable, and a polyethylene terephthalate film is more preferable.

  The resin film layer containing the titanium oxide particles preferably has a single light reflectance of 60% or more. If a single light reflectivity is used, light emitted from the light source unit cannot be sufficiently reflected, and the visibility of the keypad may be inferior.

  The blending amount of the titanium oxide particles is not particularly limited as long as the reflectance of the resin film alone is as described above and is not particularly limited. However, if the amount is too small, the reflectance may not be achieved. The above is preferable. More preferably, it is 15% by weight or more.

  The resin film is preferably stretched in terms of film strength and flexibility.

The resin film is preferably not subjected to foaming treatment in terms of strength and flexibility.
If the thickness of the resin film is thin, the strength may be inferior, and if the thickness is thick, it is not possible to follow downsizing of the device, and therefore 8-30 μm is preferable, and 10-20 μm is particularly preferable.

  The white ink preferably contains a white colorant as a light reflecting material, a binder, and a solvent.

  Examples of the white colorant include titanium dioxide, barium sulfate, zinc white, and lead white. Of these, titanium dioxide is preferable.

  It is preferable that the binder used for the white ink does not contain a halogen element such as chlorine, bromine, fluorine, or iodine. When the binder contains a halogen element, the content of the halogen element is preferably 50 ppm or less. If a halogen element is contained in a large amount, when a liquid crystal display module unit using a light-shielding pressure-sensitive adhesive sheet is used, the display performance may deteriorate due to the generation of gas due to the halogen element. When the adhesive sheet is incinerated, harmful gases are generated and the environmental load may increase.

  As the solvent used in the white ink, a general-purpose solvent can be appropriately selected and used according to the types of the white colorant and the binder.

  The white colorant is preferably contained in a proportion of 10 to 40% by weight in 100% by weight of the white ink, more preferably 15 to 30% by weight. If the amount of the white colorant is too small, the light reflectivity is lowered, and the thickness of the white layer may not be reduced while maintaining sufficient light reflectivity. When there is too much white colorant, the surface roughness of the white layer becomes too large, the adhesion between the white layer and the layer laminated on the white colorant is lowered, and there is a possibility of peeling between the layers.

  Examples of commercial products of the white ink include trade name “Panacia CVL-SP709 White” manufactured by Dainippon Ink & Chemicals, Inc. and trade name “EGS611 White” manufactured by Teikoku Ink.

  The thickness of each of the first and second white layers 12 and 13 is preferably less than 15 μm, and more preferably 10 μm or less. If the white layer is too thick, the light-shielding pressure-sensitive adhesive sheet may be too thick. The thickness of the first and second white layers 12 and 13 is preferably 2 μm or more. If the white layer is too thin, the black layer may pass through the white layer and the white layer may appear gray. If the white layer is too thin, the light transmitted through the white layer is absorbed by the black layer, and the light reflection performance of the white layer may be reduced.

  The thicknesses of the first white layer 12 and the second white layer 13 may be the same or different.

  The white colorant is preferably contained in a proportion of 30 to 80% by weight in 100% by weight of the white layer formed with the white ink. If the amount of the white colorant is too small, the light reflectivity of the light-shielding pressure-sensitive adhesive sheet is lowered, and the thickness of the white layer may not be reduced while maintaining sufficient light reflectivity. When there is too much white colorant, the surface roughness of the white layer becomes too large, the adhesion between the white layer and the layer laminated on the white colorant is lowered, and there is a possibility of peeling between the layers.

(Adhesive layer)
The pressure-sensitive adhesive layer 14 laminated on the base material of the light-shielding pressure-sensitive adhesive sheet is formed of a suitable pressure-sensitive adhesive. As such an adhesive, an acrylic adhesive or a rubber adhesive can be used. Preferably, a transparent pressure-sensitive adhesive is used. In that case, the pressure-sensitive adhesive layer may not have a through hole in the light transmitting portion 6a.

  However, it is preferable that the pressure-sensitive adhesive is also transparent. In that case, the translucent part 6a can be formed by simply forming a through hole in the light-shielding pressure-sensitive adhesive sheet.

  The circular operation key 4 is overlaid on the cross-shaped keypad 2a to which the light-shielding adhesive sheet 6 is attached. The operation key 4 is made of a transparent synthetic resin material, and only a small circular illuminated marking portion 4b is illuminated by light from below. In the present embodiment, a translucent colored sheet 7 is laminated on the circular illuminated marking portion 4a. Thereby, the illuminated marking part 4a can be made to shine so that the said translucent colored sheet 7 may exhibit a color different from another part.

  As shown in FIG. 1C, the translucent colored sheet 7 affixed to the illuminated marking portion 4a is irradiated only with the illuminated marking portion 4a as indicated by the arrow. Pass through. That is, due to the presence of the light-shielding pressure-sensitive adhesive sheet 6, light from below does not reach the portion other than the light transmitting portion 6a.

  But the light from a light source permeate | transmits upwards around the part in which the said light-shielding adhesive sheet 6 is provided. Accordingly, the entire operation key 4 is translucent and is illuminated to some extent by the light source from below. Therefore, the entire circular operation key looks bright. In the operation key 4 that looks bright, only the illuminated marking portion 4 a is brightly illuminated so as to exhibit the color of the colored sheet 7.

  In this case, when the outer shape of the lower light-shielding pressure-sensitive adhesive sheet 6 is seen, the design is inferior. Therefore, it is desirable that the light-shielding pressure-sensitive adhesive sheet 6 is difficult to recognize when viewed through the circular operation key 4.

  Therefore, it is preferable that the light-blocking pressure-sensitive adhesive sheet 6 has a white upper surface such as the white layer 12. In this case, when the upper surface is white and the entire operation key 4 has a transparent white ground glass color tone, the color difference between the two is reduced. Therefore, it becomes difficult to see the outer edge of the cross-shaped keypad or the light-shielding pressure-sensitive adhesive sheet 6, and it is difficult to make the presence of the cross-shaped keypad 2a difficult to recognize. Thus, in order to make it difficult to see the keypad 2a existing below the operation key 4, it is desirable that the color difference between the two is 2 or less.

  In the present embodiment, since the cross-shaped keypad 2a is arranged at a part below the circular operation key 4, it is difficult to see the outer shape of the cross-shaped keypad 2a, that is, the outer shape of the light-shielding adhesive sheet 6. It is desirable.

  However, in the present invention, the shape of the operation key and the keypad arranged below the operation key can be variously modified. For example, as shown in FIG. 4A, a circular operation key 22 and a rectangular key top 23 shown schematically are arranged above a keypad 21 having a single rectangular planar shape. Also good. In that case, a light-shielding pressure-sensitive adhesive sheet 24 having the same planar shape as the top surface of the keypad may be attached to the top surface of the keypad 21.

  Also in this case, since the light-shielding pressure-sensitive adhesive sheet 24 has entered the region below the operation key 22, in order to make it difficult to see the outer edge of the keypad 21, as in the case of the above-described embodiment, It is desirable that the upper surface be a color having a small color difference with respect to the transparent operation key 22. That is, when the operation key 22 is white frosted glass, the upper surface of the light-shielding pressure-sensitive adhesive sheet 24 is desirably the same as the white layer 12.

  In the present invention, the keypad to which the light-shielding pressure-sensitive adhesive sheet is attached may be present in the entire area below the operation keys. For example, below the operation key 22 shown in FIG. 4A, the keypad 21 is located in the entire area below. Therefore, the light-shielding adhesive sheet 24 affixed to the upper surface of the keypad 21 is located in the entire area below the operation keys 22. In this case, when viewed through the operation key 22 from above, the outer shape of the keypad 21 cannot be seen. Therefore, in this case, the color of the upper surface of the light-shielding pressure-sensitive adhesive sheet 24 may be selected regardless of the color of the operation key 22.

  As described above, in the mobile phone according to the modified example of the above embodiment, the operation key is substantially transparent, and in the structure in which the operation key is illuminated by the light source from below, a part of the illuminated marking portion of the operation key Can be strongly illuminated by the light from the lower light source. In the conventional example shown in FIG. 5, a light shielding plate made of a stainless steel plate is used. Therefore, the cellular phone is thinned in this way, whereas in the above embodiment, such a metal plate is used. Therefore, it is possible to reduce the thickness of portable electronic devices such as cellular phones.

  And the said light-shielding adhesive sheet 6 is stuck only on the upper surface of a required keypad. Therefore, a large light shielding sheet or a light shielding metal plate is not required. Therefore, cost can be reduced. Moreover, the usage-amount of an adhesive can be decreased, and it is hard to produce the smell of the solvent contained in an adhesive, and can reduce an environmental burden.

  Further, in the structure in which the light shielding plates made of stainless steel are stacked, even if the upper operation key is pressed with a finger, the pressing force is hardly transmitted to the keypad below the light shielding plate. On the other hand, in this embodiment, since there is no light shielding plate below the operation key 4, when the illuminated marking portion 4a of the operation key 4 is pressed with a finger, the lower keypad 2a can be easily operated with a small force. In addition, it will bend downward greatly. Therefore, the pressing force required for the operation can be reduced.

  In the above embodiment, the light-shielding pressure-sensitive adhesive sheet used in the mobile phone having the operation key pressed by the finger has been described. However, the light-shielding pressure-sensitive adhesive sheet of the present invention is combined with the operation key pressed by the finger. The present invention may be used not only for applications that are used in combination with operation keys such as touch sensor keys and optical keys. In any case, when illuminating the operation part that is touched by the finger or the like or a part other than the operation part in order to clarify the part that the finger or the like contacts, In order to clarify this part, the light-shielding pressure-sensitive adhesive sheet according to the present invention is preferably used. By using the light-shielding pressure-sensitive adhesive sheet according to the present invention, it is possible to increase a contrast difference, a color difference, and the like between the illuminated part and the other part, thereby reliably preventing an erroneous operation.

  Although the mobile phone has been described, the present invention is not limited to the mobile phone, and can be widely used in structures that partially illuminate operation keys of portable electronic devices such as portable game devices and electronic notebooks. It can also be used for a keyboard of a personal computer.

Example 1
A white resin film (trade name “Teflex” manufactured by Teijin Ltd., polyethylene terephthalate resin film containing titanium oxide particles, thickness: 13 μm) was prepared.

  Next, 30% by weight of a urethane resin (halogen element content: less than 50 ppm) as a binder, 10% by weight of carbon black having an average particle size of 0.03 μm as a black colorant, and ethyl acetate, toluene and isopropyl alcohol are mixed. A black ink made of 60% by weight of a black ink (carbon black: 10% by weight) was prepared.

  And the black ink was apply | coated and dried by the gravure printing on the other intermediate | middle layer of the said white resin film, and the 0.8-micrometer-thick thin layer was formed. The procedure of applying and drying the black ink was repeated 5 times in total to form a black layer having a thickness of 4 μm.

  Next, 25% by weight of a urethane resin (halogen element content: 50 ppm or less) as a binder, 25% by weight of titanium dioxide as a white colorant, and 50% by weight of a solvent obtained by mixing ethyl acetate, toluene and isopropyl alcohol. White ink (titanium dioxide: 25% by weight) was applied to one intermediate layer by gravure printing and dried to form a thin layer having a thickness of 1.3 μm. The procedure of applying and drying the above white ink in layers was repeated a total of 3 times to form a light reflecting layer having a thickness of 4.0 μm. In addition, the content rate of the titanium dioxide in each light reflection base layer was 50 weight%.

Furthermore, the white ink was applied to the surface of the white resin film opposite to the surface on which the black layer was formed, thereby forming a 1.3 μm white layer.
This formed the light-shielding sheet base material which has a laminated structure of white layer / white resin film / black layer / white layer.

  Subsequently, an acrylic pressure-sensitive adhesive was applied to the white resin film side of the light-shielding sheet base material and dried to form a pressure-sensitive adhesive layer having a thickness of 1.5 μm. Thus, a light-shielding pressure-sensitive adhesive sheet having a laminated structure of pressure-sensitive adhesive layer / white layer / white resin film / black layer / white layer was produced.

(Comparative Example 1)
The same operation as in Example 1 was performed except that the white layer was not provided.

  As a result, a light-shielding pressure-sensitive adhesive sheet having a laminated structure of pressure-sensitive adhesive layer / white resin film / black layer was produced.

(Evaluation)
The light reflectance, light shielding properties and aesthetics of the obtained light shielding sheet substrate were evaluated in the following manner.

(Light reflectance)
The total light reflectance at 500 nm was measured for the light reflecting layer of the light shielding sheet substrate in accordance with JIS K7105. In each of Examples and Comparative Examples, measurement was performed from the white resin film side. The result of Example 1 was 73%, and that of Comparative Example 1 was 70%.

(Light shielding)
The total light reflectance based on JIS K7105 was measured about the light shielding layer of the adhesive tape for a display apparatus assembly. In the examples and comparative examples, both were 0.1% or less.

(Aesthetic)
A translucent sheet made of PET (manufactured by Teijin DuPont, “Teijin Tetron Film U2”, thickness 38 μm) and a white sheet (manufactured by Mitsubishi Chemical Polyester Film, “Diafoil”) were prepared.

  The light-shielding pressure-sensitive adhesive sheet prepared in Example 1 and Comparative Example 1 was cut off by 20 × 20 mm. And after making the hole of diameter 2mm in the center part, it pinched | interposed between the transparent sheet and the white sheet. Illuminated with a light source (xenon light, “ELPA DOP-207” manufactured by Asahi Denki Co., Ltd.) from the back side of the white sheet, the effect on visual appearance was observed. The both sides of the light-shielding pressure-sensitive adhesive sheet were observed.

  In the light-shielding pressure-sensitive adhesive sheet of Example 1, the boundary of the light-shielding pressure-sensitive adhesive sheet was difficult to understand regardless of which side was used on the transparent sheet side.

  In the light-shielding pressure-sensitive adhesive sheet of Comparative Example 1, not only when the black surface was directed to the transparent sheet side, but also when the white resin film side was directed to the transparent sheet side, the black silhouette was prominent.

(A) is an exploded perspective view of a mobile phone as a portable electronic device according to an embodiment of the present invention, (b) is a light shielding property having a cross-shaped planar shape on a cross-shaped keypad. It is a typical perspective view which shows the state in which the adhesive sheet is affixed, (c) is the part by which the light-shielding adhesive sheet is affixed on the cross-shaped keypad, and the operation key is located above It is front sectional drawing which shows typically. 1 is a schematic plan view showing a main part of a mobile phone according to an embodiment of the present invention. It is front sectional drawing which shows the preferable laminated structure of the light-shielding adhesive sheet used by one Embodiment of this invention. (A) And (b) is a typical perspective view and a typical top view for demonstrating the modification of the combination of the keypad and operation key in the portable electronic device of this invention. It is a typical disassembled perspective view for demonstrating an example of the conventional mobile telephone. It is front sectional drawing for demonstrating the conventional illumination color key top.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wiring board 1a-1c ... Metal dome 2 ... Key base 2a-2c ... Keypad 4 ... Operation key 5 ... Keypad 6 ... Light-shielding adhesive sheet 6a ... Translucent part 6b ... Base material 6c ... Adhesive layer 7 ... Translucent colored sheet 11 ... black layer 12 ... first white layer 13 ... second white layer 14 ... adhesive layer 21 ... keypad 22 ... operating key 23 ... key top 24 ... light-shielding adhesive sheet

Claims (5)

A light-shielding pressure-sensitive adhesive sheet disposed between an operation key of a portable electronic device and a light source,
A translucent portion corresponding to the illuminated marking portion of the operation key; a black layer; a first white layer formed on one surface of the black layer; and a second layer formed on the other surface of the black layer. A light-shielding pressure-sensitive adhesive sheet, which is a laminated sheet having a white layer.   The light-shielding pressure-sensitive adhesive sheet according to claim 1, further comprising a pressure-sensitive adhesive layer formed on the surface of the first or second white layer. An operation key that is substantially transparent and has an illuminated marking portion that is illuminated;
A light source for irradiating the operation key with light from below;
In a portable electronic device comprising a keypad disposed between the operation key and the light source,
Attached to the operation key side surface of the keypad, further comprising the light-shielding pressure-sensitive adhesive sheet according to claim 1 or 2,
At least a part of an outer edge of the light-shielding pressure-sensitive adhesive sheet is located below the operation key.   The portable electronic device according to claim 3, wherein all of the outer edges of the keypad are located below the operation keys.   The portable electronic device according to claim 3, wherein a portion of the portable electronic device around the operation key has an outer surface made of a translucent member.

Images