JP2004219985A - Double-sided light emitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided light emitter which is thin, light in weight and inexpensive. <P>SOLUTION: The double-sided light emitter 10 is used for a main liquid crystal display unit 18 and a sub liquid crystal display unit 20 which are stacked in the thickness direction and is attached to the same frame 26. Double-sided reflective sheet 36 made of metal guides the light rays reflected by the upper surface and the lower surface thereof respectively to the main and sub liquid crystal display units 18, 20. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a double-sided light emitting device, and more particularly to, for example, a double-sided light emitting device used for two liquid crystal display units provided on a lid of a foldable mobile phone so as to overlap in a thickness direction.

  FIG. 8 shows an example of a conventional foldable mobile phone. In this mobile phone 1, a sub liquid crystal display device 2 and a main liquid crystal display device 3 are provided on an outer surface and an inner surface of a lid 1a. 7A, the main liquid crystal display device 3 disposed on the upper side includes a main liquid crystal display unit 4 and a main surface light emitting unit 5, and each of these units 4 , 5 are housed in a main frame 6.

  Further, the sub liquid crystal display device 2 arranged on the lower side of the cross-sectional view of FIG. 7A includes a sub liquid crystal display unit 7 and a sub surface light emitting unit 8, and these units 7, 8 , Sub-frame 9. The main and sub liquid crystal display devices 3 and 2 are mounted on the upper and lower surfaces of the main and sub liquid crystal display devices 3 with the partition plate 1b interposed therebetween.

  FIG. 7B is a partially enlarged cross-sectional view of the main and sub liquid crystal display devices 3 and 2 shown in FIG. As shown in the figure, the main liquid crystal display unit 4 includes a polarizing plate 4a, a glass plate 4b, and a polarizing plate 4a, and the main surface light emitting unit 5 includes a lens sheet (prism sheet) 5a, a light guide plate 5b, and a reflection plate. The seat 5c is provided.

  Similarly, the sub liquid crystal display unit 7 includes a polarizing plate 7a, a glass plate 7b, and a polarizing plate 7a, and the sub surface light emitting unit 8 includes a lens sheet (prism sheet) 8a, a light guide plate 8b, and a reflection sheet 8c. ing. The main (sub) liquid crystal display unit 4 (7) and the main (sub) surface light-emitting unit 5 (8) are adhered to each other by the light-shielding double-sided adhesive tape 4 c (7 c), and the main (sub) frame 6 is attached. It is adhered to (9).

  According to the main and sub liquid crystal display devices 3 and 2, as shown in FIG. 7B, the main and sub surface light emitting units 5 and 8 and the partition plate (thickness A) 1b, The bottom walls (thickness B) 6a, 9a of the sub-frames 6, 9 and the reflection sheets (thickness C) 5c, 8c are arranged. The total thickness of these is D. The total thickness of the main and sub liquid crystal display devices 3 and 2 is E.

Further, there is a liquid crystal display unit in which a liquid crystal display unit is provided on both the front surface and the rear surface, and the cross-sectional shape of the light guide plate for the backlight is triangular. The two light guide plates have a square cross section when they are combined. Therefore, when the cross section is triangular, the thickness can be reduced as compared with a case where two light guide plates having a quadrangular cross section are overlapped (for example, see Patent Document 1).
JP 2002-244133 A [G02F 1/13357, G09F 9/00]

  However, since the conventional main and sub liquid crystal display devices 3 and 2 shown in FIG. 7 are obtained by simply superposing the two liquid crystal display devices 3 and 2, they are bulky by the thickness D shown in FIG. There is a problem that is large. Therefore, the structure is disadvantageous, especially for the mobile phone 1 which is strongly demanded to be thin and lightweight.

  In the light guide plate of Patent Document 1 having a triangular cross-sectional shape, it is unclear how much the thickness of the double-sided liquid crystal display device can be specifically reduced depending on how the light guide plate is attached to the frame. It is. Although two liquid crystal modules having the same size are described, the liquid crystal modules having different sizes are not configured to be thin.

  Therefore, a main object of the present invention is to provide a double-sided light emitting device that is thin, lightweight, and inexpensive.

  The invention according to claim 1 is a double-sided light emitting device used for two liquid crystal display units that overlap in the thickness direction, and includes one common frame and two light emitting units attached to the common frame. A double-sided light emitting device including a light guide plate for supplying light from a light emission surface to a corresponding liquid crystal display unit, and a first reflector attached to a surface of the light guide plate opposite to the light emission surface.

  According to the first aspect of the invention, since the double-sided light emitting device is mounted on the common frame, for example, the bottom wall 9a and the partition plate 1b of the sub-frame 9 shown in FIG. The configuration may be such that the omitted sub-frame 9 and the main frame 6 are combined. Thereby, it can be made thinner than the conventional one by at least the thickness of the bottom wall 9a and the partition plate 1b.

  A second aspect of the present invention is the double-sided light emitting device according to the first aspect, wherein the light guide plate of each light emitting unit of the light emitting unit has a constant thickness.

  According to the second aspect of the present invention, for example, the cross section and the vertical cross section of the light guide plate are rectangular, and the two light guide plates are stacked in the thickness direction.

  A third aspect of the present invention is the double-sided light emitting device according to the first aspect, wherein the thickness of the light guide plate of each light emitting unit of the light emitting unit gradually changes.

  According to the invention of claim 3, the thickness of one side of the light guide plate is large, the thickness gradually decreases in the longitudinal direction, and the thickness of the other side becomes small. When two light guide plates are stacked in the thickness direction, when the thickness of one light guide plate is set to be smaller than that of the other light guide plate, the thickness is smaller than when the light guide plates having a certain thickness are stacked. can do.

  According to a fourth aspect of the present invention, there is provided the double-sided light emitting device according to the second or third aspect, wherein a projection is provided on the light incident surface side of the light guide plate of each light emitting unit of the light emitting unit.

  According to the fourth aspect of the present invention, by providing the projection on the light incident surface side of the light guide plate, the light incident surface of the light guide plate facing the light source is increased, so that the thickness of the light guide plate where the projection is not provided is reduced. Even if it is thin, the amount of light incident on the light guide plate from the light source can be secured, and the display screen can be brightened.

  A fifth aspect of the present invention is the double-sided light emitting device according to any one of the first to fourth aspects, wherein the first reflector of each light emitting unit is individually provided.

  According to the invention of claim 5, for example, a frame can be interposed between the two first reflecting members. With the interposed frame, the mechanical strength of the double-sided light emitting device can be increased.

  A sixth aspect of the present invention is the double-sided light emitting device according to any one of the first to fourth aspects, wherein the first reflector of each light emitting unit is provided in common.

  According to the invention of claim 6, light can be reflected toward each surface of the double-sided light emitting device by the common first reflector, so that at least compared with the case where the first reflector is used separately, The thickness of the two-sided light emitting device can be reduced by the thickness of one first reflector.

  The invention according to claim 7 is the double-sided light emitting device according to claim 5 or 6, wherein the first reflector is made of metal.

  According to the invention of claim 7, the mechanical strength of the double-sided light emitting device can be increased by using the first reflecting material made of metal. Therefore, for example, the frame can be made of a synthetic resin having relatively low strength, and the weight is reduced.

  The invention of claim 8 is the double-sided light emitting device according to any one of claims 5 to 7, wherein the common frame is made of metal.

  According to the eighth aspect of the invention, the mechanical strength of the double-sided light emitting device can be increased by forming the common frame from metal. In this case, for example, the first reflector is made of a synthetic resin having relatively low strength, so that the weight can be reduced.

  A ninth aspect of the present invention is the double-sided light emitting device according to the eighth aspect, wherein a second reflector is provided on a side surface of the light guide plate of each light emitting unit of the light emitting unit.

  According to the ninth aspect of the present invention, for example, the frame can be formed of a metal whose surface state is unlikely to reflect light. In this case, it is not necessary to make the surface of the metal reflect light, and the mechanical strength of the frame can be increased.

  By attaching the double-sided light emitting device to the common frame, the thickness of the double-sided light emitting device can be made thinner than the conventional one by at least the thickness of the bottom wall 9a and the partition plate 1b shown in FIG. And it becomes lighter by that much, and material cost can be reduced. Further, since the liquid crystal display unit can be used for two liquid crystal display units having different sizes, a wide range of selection of a liquid crystal display unit to which the double-sided light emitting device can be applied can be adopted.

  Further, when the common first reflector is used, the two-sided light emitting device can be made thinner and lighter by at least the thickness of one first reflector than in the case of using different first reflectors. It becomes. Further, since the common first reflecting material is used, the first reflecting material can be attached by one attaching operation, and thus, the assembly cost can be reduced.

  The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  A double-sided light emitting device according to a first embodiment of the present invention will be described with reference to FIG. This double-sided light emitting device 10 can be used, for example, as a backlight of a double-sided liquid crystal display device 14 applied to a mobile phone 12 equivalent to the foldable mobile phone 1 shown in FIG. The mobile phone 12 includes a main body (not shown) and a lid 16, and the main body and the lid 16 are relatively rotatably connected to each other via a hinge (not shown). I have. This mobile phone 12 can be opened and closed in an open state, as in FIG. 8B, and in a folded state, as in FIG. 8A. The main body is provided with a plurality of keys, and the lid 16 is provided with the double-sided liquid crystal display device 14 of this embodiment.

  FIG. 1A is a cross-sectional view of the double-sided liquid crystal display device 14 provided on the lid 16. The double-sided liquid crystal display device 14 includes a main liquid crystal display unit 18 and a sub liquid crystal display unit 20 arranged on the inner surface and the outer surface of the lid 16 respectively. The inner surface of the lid 16 is the upper surface of the lid 16 shown in FIG. 1A, which is the inside of the lid 16 when the mobile phone 12 is folded. The outer surface of the lid 16 is the lower surface of the lid 16 shown in FIG. Further, inside the main liquid crystal display unit 18, a main surface light emitting unit (side light type) 22 as a backlight used therein is provided. Inside the sub liquid crystal display unit 20, a sub surface light emitting unit (side light type) 24 as a backlight used for the sub liquid crystal display unit 20 is provided. The main liquid crystal display unit 18, the main surface light emitting unit 22, the sub liquid crystal display unit 20, and the sub surface light emitting unit 24 are arranged so as to overlap in the thickness direction, and are accommodated in a common frame 26. The main liquid crystal display unit 18 and the like constitute the double-sided liquid crystal display device 14. The main surface light-emitting unit 22 and the sub surface light-emitting unit 24 constitute the double-sided light emitting device 10.

  FIG. 1B is a partially enlarged cross-sectional view of the double-sided liquid crystal display device 14 shown in FIG. As shown in FIG. 1B, the main liquid crystal display unit 18 includes a polarizing plate 28, a glass plate 30, and a polarizing plate 28, and the main surface light emitting unit 22 includes a lens sheet (prism sheet) 32, a light guide plate. 34, a first reflecting material 36. The main liquid crystal display unit 18 and the main surface light emitting unit 22 are adhered to the frame 26 in a state where they are adhered to each other by a light-shielding double-sided adhesive tape 38. The first reflector 36 is a double-sided reflection sheet, for example, and may be a double-sided reflection plate or a double-sided reflection film.

  Similarly, the sub liquid crystal display unit 20 includes a polarizing plate 40, a glass plate 42, and a polarizing plate 40, and the sub surface light emitting unit 24 includes a lens sheet (prism sheet) 44, a light guide plate 46, and a double-sided reflection sheet 36. Have. In this double-sided reflection sheet 36, the reflection surface 36a formed on the upper surface is used for the main surface light emitting unit 22, and the reflection surface 36b formed on the lower surface is used for the sub surface light emitting unit 24. Things. Therefore, the double-sided reflection sheet 36 is shared by the main surface light-emitting unit 22 and the sub surface light-emitting unit 24. The sub liquid crystal display unit 20 and the sub surface light emitting unit 24 are adhered to the frame 26 in a state where they are adhered to each other by the light-shielding double-sided adhesive tape 48.

  The polarizing plate 28, the light guide plates 34 and 46 of the main liquid crystal display unit 18, the main surface light emitting unit 22, the sub liquid crystal display unit 20, and the sub surface light emitting unit 24 are, for example, rectangular plate members, respectively. The shape of the longitudinal section and the transverse section is rectangular, and the thickness is constant. The polarizer 28, the glass plate 30, the polarizer 28, the lens sheet 32, and the light guide plate 34 of the main liquid crystal display unit 18 and the main surface light emitting unit 22 correspond to the corresponding polarization of the sub liquid crystal display unit 20 and the sub surface light emitting unit 24. The planar shape is formed larger than each of the plates 40 and the like.

  As shown in FIG. 1A, the frame 26 includes a main side wall 50 formed in a rectangular frame shape, a rectangular bottom wall 52 formed below the main side wall 50, And a rectangular frame-shaped sub-side wall 54 formed on the lower surface. The main side wall 50 opens upward, and the sub side wall 54 opens downward. The main side wall 50 has a larger planar shape than the sub side wall 54.

  Along the upper surface of the rectangular outer peripheral edge of the bottom wall 52, a main convex portion 56 having a rectangular cross section is formed. As shown in FIG. 1B, the lens sheet 32, the light guide plate 34, and the double-sided reflection sheet 36 are arranged on the upper surface of the bottom wall 52 in a state of being superposed. Then, a rectangular frame-shaped light-shielding double-sided adhesive tape 38 is attached so as to straddle the upper surface of the lens sheet 32 and the upper surface of the main convex portion 56. The polarizing plate 28, the glass plate 30, and the polarizing plate 28 are superposed on the upper surface of the main convex portion 56 via the light-shielding double-sided adhesive tape 38, and are arranged in a state of being adhered to each other.

  A rectangular opening 58 is formed at the center of the bottom wall 52, and the inner edge of the opening 58 is formed as a sub-projection 60. The sub side wall 54 is formed downward from the base end of the sub convex portion 60. As shown in FIG. 1B, the lens sheet 44 and the light guide plate 46 are arranged on the lower surface of the double-sided reflection sheet 36 in a state of being overlapped. Then, a rectangular frame-shaped light-shielding double-sided adhesive tape 48 is attached so as to straddle the lower surface of the lens sheet 44 and the lower surface of the sub-convex portion 60. The polarizing plate 40, the glass plate 42, and the polarizing plate 40 are superposed on the lower surface of the sub-convex portion 60 with the light-shielding double-sided adhesive tape 48 interposed therebetween, and are arranged in a state of being adhered to each other.

  The double-sided liquid crystal display device 14 thus formed is housed in a case 62 forming the lid 16 as shown in FIG. A main screen 64 is provided on the inner surface side of 16. A sub-screen 66 is provided on the outer surface of the lid 16 so as to cover the sub-liquid crystal display unit 20.

  The main and sub liquid crystal display units 18 and 20 are the same as those of the related art, and a detailed description thereof will be omitted. Although not shown in the figure, the main and sub surface light-emitting units 22 and 24 are respectively provided with main and sub light sources made of, for example, LEDs (light emitting diodes) or fluorescent lamps. Each light source is provided at a position facing the light incident surface of the corresponding light guide plate 34, 46, and may be a point light source or a linear light source.

  The light from the main light source is reflected on a prism surface formed on the lower surface of the light guide plate 34 or on the upper surface 36a of the double-sided reflection sheet 36, and is emitted from the emission surface (upper surface) of the light guide plate 34 to form a lens sheet. 32, the polarizing plate 28, the glass plate 30, and the polarizing plate 28 to reach the observer's eyes. The light reaching the observer is display light for displaying an image or the like. Similarly, the light from the sub light source is reflected by the prism surface formed on the upper surface of the light guide plate 46 or the lower surface 36b of the double-sided reflection sheet 36, and is emitted from the emission surface (lower surface) of the light guide plate 46. , Through the lens sheet 44, the polarizing plate 40, the glass plate 42 and the polarizing plate 40 to reach the eyes of the observer. The light reaching the observer is display light for displaying an image or the like.

  The frame 26 is formed by mixing, for example, titanium oxide or the like with a synthetic resin such as polycarbonate or acrylic, and is formed so that the inner surface reflects light. Therefore, light emitted from the side surfaces of the light guide plates 34 and 46 is reflected by the inner surfaces (reflection surfaces 56a and 60a) of the protrusions 56 and 60 formed on the frame (main side wall 50 and sub-side wall 54) 26. Then, the light enters the light guide plates 34 and 46 and exits from the exit surface. Therefore, light from each light source can be used efficiently.

  According to the double-sided liquid crystal display device 14 configured as described above, since the double-sided liquid crystal display device 14 (double-sided light emitting device 10) is attached to the common frame 26 as shown in FIG. The thicknesses A, B, B of the partition plate 1b and the bottom walls 6a, 9a shown in B) can be reduced. Then, the light is reflected toward the respective light guide plates 34 and 46 provided in the main and sub surface light emitting units 22 and 24 by using one double-sided reflection sheet (thickness C) 36. is there. Therefore, as shown in FIG. 7B, the thickness C of one reflection sheet can be reduced as compared with the case where two reflection sheets (thickness 2C) 5c and 8c are used. As described above, since the thickness can be reduced, the thickness (thickness F = EA-2BC) and the weight can be reduced, and the material cost can be reduced. Furthermore, since the double-sided liquid crystal display device 14 is mounted on the common frame 26, when the double-sided liquid crystal display device 14 is mounted on, for example, the case 62 of the mobile phone 12, only one mounting operation is required, and the assembly cost can be reduced. .

  The double-sided reflection sheet 36 is made of, for example, metal such as stainless steel or aluminum, and is formed by depositing, for example, silver on each surface of the upper surface 36a and the lower surface 36b, and both surfaces 36a, 36b are made of light. Is formed as a reflection surface so as to reflect light. Since the double-sided reflection sheet 36 is made of metal as described above, the mechanical strength of the double-sided liquid crystal display device (double-sided light emitting device 10) 14 can be increased. Therefore, the frame 26 can be made of, for example, a synthetic resin, which is lightweight. Of course, the double-sided reflection sheet 36 can reflect the light emitted from the respective prism surfaces of the light guide plates 34 and 46 and emit the light from the emission surfaces of the light guide plates 34 and 46. Therefore, light from each light source can be used efficiently.

  Further, since the double-sided light emitting device 10 can be used for two main and sub liquid crystal display units 18 and 20 having different sizes, the range of selection of the liquid crystal display unit to which the double-sided light emitting device 10 can be applied is widened. It can be taken and is practical.

  Although the light guide plates 34 and 46 having a constant thickness are used, the light guide plates 34 and 46 shown in FIG. 2 may be used instead. The light guide plates 34 and 46 have a rectangular cross-section (a plane parallel to the light-incident surface) and a constant thickness, but a vertical cross-section (a surface perpendicular to the light-incident surface) has a trapezoidal shape. The thickness of the face sides 34a and 46a is large, the thickness gradually decreases, and the thickness on the opposite side decreases. When the light guide plates 34 and 46 are stacked in the thickness direction, the side where the thickness of the light guide plate 34 is large is set to the side where the thickness of the light guide plate 46 is small, and the side where the thickness of the light guide plate 34 is small is set to the side where the thickness of the light guide plate 46 is large. The two light sources are arranged so as to sandwich the light guide plates 34 and 46, respectively. By doing so, the thickness of the two light guide plates 34 and 46 can be reduced as compared with the case where the light guide plates having a constant thickness are stacked, and accordingly, the weight can be reduced. Here, the light guide plates 34 and 46 have a trapezoidal vertical sectional shape, but are not limited as long as the thickness gradually changes, such as a wedge shape.

  Further, the light guide plates 34 and 46 shown in FIG. 3 may be used. The light guide plates 34 and 46 have a rectangular cross-sectional shape and a constant thickness, but have a trumpet-shaped vertical cross-sectional shape. In the trumpet type, the thickness of the light guide plates 34 and 46 is constant, but only the light incident surface sides 34a and 46a protrude (projections 34b and 46b), and the thickness is large. When the light guide plates 34 and 46 are overlapped in the thickness direction, the light guide plates 34 and 46 are directed in the direction in which the respective protrusions 34b and 46b face each other, and the protrusions 34b of the light guide plate 34 do not overlap the light guide plate 46, and the light guide plate 46 The light guide plates 34 and 46 are shifted so that only the portions without the respective protrusions 34b and 46b are overlapped so that the protrusion 46b does not overlap the light guide plate 34. In this manner, the projections 34b and 46b are provided on the light entrance surfaces 34a and 46a of the light guide plates 34 and 46, and by increasing the thickness, the amount of light incident on the light guide plates 34 and 46 can be secured. The thickness s of the portions of the light guide plates 34 and 46 without the protrusions 34b and 46b can be made smaller than the thickness w of the light guide plates 34 and 46 of the double-sided liquid crystal display device 14 shown in FIG. Therefore, the thickness in which the two light guide plates 34 and 46 are stacked can be reduced, and accordingly, the weight can be reduced. Here, the projections 34b and 46b are provided on the light guide plates 34 and 46 having a constant vertical cross-sectional shape, but the projections 34b and 46b may be provided on the light guide plates 34 and 46 whose thickness gradually changes.

  Next, a two-sided light emitting device 68 according to a second embodiment of the present invention will be described with reference to FIG. This double-sided light emitting device 68 can be used as a backlight of a double-sided liquid crystal display device 70 applied to the foldable mobile phone 12 equivalent to the first embodiment. The difference between the first embodiment and the second embodiment is that the frames 26 and 72 and the first reflectors 36 and 74 are different. The other parts are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and their detailed description is omitted.

  The frame 72 of the second embodiment is made of a metal such as a magnesium alloy or an aluminum alloy. Then, instead of the convex portions 56 and 60 shown in FIG. 1B, the second reflective members 76 and 78 made of synthetic resin and having the same shape as the convex portions 56 and 60 correspond to the respective positions. It is provided in. In addition, the reflection members 76 and 78 made of synthetic resin may be a reflection sheet or a reflection film.

  As described above, by making the frame 72 made of metal, the mechanical strength of the double-sided liquid crystal display device (double-sided light emitting device 68) 70 can be increased. Therefore, the first reflective member 74 can be made of an inexpensive and lightweight double-sided reflective sheet made of synthetic resin, having relatively low strength. The double-sided reflection sheet 74 is a sheet made of a synthetic resin such as PET (polyethylene terephthalate), for example, and has silver deposited on both surfaces thereof.

  The reason why the reflecting members 76 and 78 are provided so as to face the side surfaces of the light guide plates 32 and 46 instead of the respective convex portions 56 and 60 of the frame 26 of the first embodiment is that, for example, the frame 72 is provided on the surface thereof. In the case where the metal is hard to reflect light, the surface of the metal surface facing the side surfaces of the light guide plates 34 and 46 does not need to be finished as a reflecting surface so as to reflect light. is there. As a result, the processing cost can be reduced. The thickness F of the double-sided liquid crystal display device 70 of the second embodiment can be smaller than the thickness F of the first embodiment. This is because the thickness of the metal double-sided reflection sheet 36 of the first embodiment is, for example, about 0.2 mm, whereas the thickness of the synthetic resin double-sided reflection sheet 74 of the second embodiment is, for example, about 0.2 mm. Is about 0.065 mm.

  Next, a two-sided light emitting device 80 according to a third embodiment of the present invention will be described with reference to FIG. This double-sided light emitting device 80 can be used as a backlight of a double-sided liquid crystal display device 82 applied to the foldable mobile phone 12 equivalent to the first embodiment. The first embodiment differs from the third embodiment in that the frames 26 and 84 and the first reflectors 36, 86 and 88 are different. The first reflector 36 of the first embodiment is a double-sided reflection sheet, whereas the first reflectors 86 and 88 of the third embodiment are reflection sheets. The other parts are the same as those of the first embodiment, and the same parts are denoted by the same reference numerals and their detailed description is omitted.

  In the frame 84 of the third embodiment, as shown in FIG. 5, a bottom wall 94 is interposed between a main surface light emitting unit 90 and a sub surface light emitting unit 92. That is, in the first embodiment, as shown in FIG. 1, the opening 58 is formed in the center of the bottom wall 52, and the opening 58 is closed by the bottom wall 94. The bottom wall 94 is formed on the same plane as the bottom wall 52. On the upper surfaces of the bottom walls 52 and 94, a reflection sheet 86 for reflecting light toward the light guide plate 34 of the main surface light emitting unit 90 is disposed. On the lower surface of the bottom wall 94, a reflection sheet 88 for reflecting light toward the light guide plate 46 of the sub surface light emitting unit 92 is disposed.

  In this way, separate reflecting sheets 86 and 88 are arranged for the main surface light emitting unit 90 and the sub surface light emitting unit 92, and a bottom wall 94 is formed between the two reflecting sheets 86 and 88. Thereby, the mechanical strength can be increased as compared with the frame 26 of the first embodiment. However, each of the reflection sheets 86 and 88 is a sheet made of a synthetic resin such as PET, for example, and has silver deposited on at least one side thereof. Each of the reflection sheets 86 and 88 may be a reflection plate or a reflection film. The frame 84 is also made of the same synthetic resin as in the first embodiment. The thickness H of the double-sided liquid crystal display device 82 of the third embodiment is larger than the thickness F of the first embodiment by the thickness of the bottom wall 52 and the reflection sheet (B + C).

  Next, a two-sided light emitting device 96 according to a fourth embodiment of the present invention will be described with reference to FIG. This double-sided light emitting device 96 can be used as a backlight of a double-sided liquid crystal display device 98 applied to a foldable portable telephone 12 similar to the third embodiment. The difference between the third embodiment and the fourth embodiment is that the frames 84 and 100 are different. Other than this, the third embodiment is the same as the third embodiment, the same parts are denoted by the same reference numerals, and their detailed description is omitted.

  The frame 100 of the fourth embodiment is made of a metal such as a magnesium alloy equivalent to that of the second embodiment. Then, instead of the convex portions 56 and 60 shown in FIG. 5 (B), reflecting members 76 and 78 made of synthetic resin and having the same shape as the convex portions 56 and 60 are provided at the corresponding positions. It is.

  As described above, by making the frame 100 made of metal, the mechanical strength of the double-sided liquid crystal display device (double-sided light emitting device 96) 98 can be increased.

  In place of the convex portions 56, 60 of the frame 84 of the third embodiment, the reflecting members 76, 78 are provided so as to face the side surfaces of the light guide plates 34, 46, as shown in FIG. This is the same reason.

  However, in the first embodiment, the double-sided reflection sheet 36 is made of metal, and for example, silver is vapor-deposited on both surfaces to form a reflection surface that reflects light. However, other configurations may be used. For example, a reflection sheet made of a synthetic resin may be attached to both surfaces of a metal sheet made of stainless steel. Each reflection sheet has a surface facing each of the light guide plates 34 and 46 formed as a reflection surface that reflects light. Further, for example, both surfaces of a metal sheet made of stainless steel may be polished and finished as a reflecting surface that reflects light.

  Of course, the double-sided reflection sheets 36 and 74 and the reflection sheets 86 and 88 of the first to fourth embodiments may be made of metal as described in the embodiment or made of synthetic resin. Further, the frame 26 and the like in each embodiment may be made of metal as described in the embodiment or a synthetic resin.

  In the second and fourth embodiments shown in FIGS. 4 and 6, the reflecting members 76 and 78 are provided instead of the convex portions 56 and 60 shown in FIGS. 1B and 5B. Other configurations are also possible. For example, instead of the reflective members 76 and 78, metal convex portions are formed integrally with the frames 72 and 100, and a reflective sheet is attached to a surface of each convex portion facing the side surface of the light guide 34 or 46. It may be attached or coated to form a reflective surface. Of course, for example, even when the frame 26 is made of synthetic resin, if the frame 26 itself is not formed so as to reflect light, the surface of each of the convex portions 56, 60 facing the side surfaces of the light guides 34, 46 is formed. For example, a reflective sheet may be attached, or the surface may be coated to form a reflective surface.

  In the first to fourth embodiments, the double-sided light emitting device 10 and the like of the present invention are applied to the double-sided liquid crystal display device 14 and the like used in the mobile phone 12. May be applied.

1A is a cross-sectional view showing a double-sided liquid crystal display device to which a double-sided light emitting device according to a first embodiment of the present invention is applied, and FIG. 1B is a partially enlarged cross-sectional view of the double-sided liquid crystal display device shown in FIG. It is. 2A is a longitudinal sectional view showing a double-sided liquid crystal display device to which a double-sided light emitting device according to another embodiment of the present invention is applied, and FIG. 2B is a partially enlarged sectional view of the double-sided liquid crystal display device shown in FIG. It is. 3A is a longitudinal sectional view showing a double-sided liquid crystal display device to which a double-sided light emitting device according to another embodiment of the present invention is applied, and FIG. 3B is a partially enlarged sectional view of the double-sided liquid crystal display device shown in FIG. It is. FIG. 7 is a partially enlarged cross-sectional view showing a double-sided liquid crystal display device to which the double-sided light emitting device according to the second embodiment of the present invention is applied. 5A is a cross-sectional view showing a double-sided liquid crystal display device to which a double-sided light emitting device according to a third embodiment of the present invention is applied, and FIG. 5B is a partially enlarged cross-sectional view of the double-sided liquid crystal display device shown in FIG. It is. FIG. 13 is a partially enlarged cross-sectional view showing a double-sided liquid crystal display device to which the double-sided light emitting device according to the fourth embodiment of the present invention is applied. FIG. 8A is a cross-sectional view of a cover of a conventional mobile phone provided with a main liquid crystal display device and a sub liquid crystal display device, as viewed from the direction of the line VA-VA in FIG. 8B, and FIG. FIG. 4 is a partially enlarged cross-sectional view of the lid shown in FIG. 8A is a front view showing a folded state of a conventional mobile phone having a main liquid crystal display device and a sub liquid crystal display device, and FIG. 8B is a front view showing an open state of the mobile phone shown in FIG. .

Explanation of reference numerals

10, 68, 80, 96 ... double-sided light emitting device 12 ... mobile phone 14, 70, 82, 98 ... double-sided liquid crystal display device 16 ... lid 18 ... main liquid crystal display unit 20 ... sub liquid crystal display unit 22, 90 ... main surface light emission Units 24, 92 ... Sub surface light-emitting units 26, 72, 84, 100 ... Frames 28, 40 ... Polarizers 30, 42 ... Glass plates 32, 44 ... Lens sheets 34, 46 ... Light guide plates 34a, 46a ... Light entrance surfaces 34b 46b Projection 36, 74 Double-sided reflection sheet 38, 48 Light-shielding double-sided adhesive tape 50 Main side wall 52, 94 Bottom wall 54 Sub-side wall 56 Main projection 60 Sub-projection 76, 78 Second reflection 86,88… Reflective sheet

Claims (9)

A double-sided light emitting device used for two liquid crystal display units overlapping in a thickness direction,
Comprising one common frame, and two light emitting units attached to the common frame,
Each light emitting unit includes a light guide plate for supplying light from a light emission surface to a corresponding liquid crystal display unit, and a first reflector attached to a surface of the light guide plate opposite to the light emission surface. Light emitting device.   The double-sided light emitting device according to claim 1, wherein the thickness of the light guide plate of each light emitting unit of the light emitting unit is constant.   The double-sided light emitting device according to claim 1, wherein the thickness of the light guide plate of each light emitting unit of the light emitting unit changes gradually.   The double-sided light emitting device according to claim 2, wherein a projection is provided on a light incident surface side of the light guide plate of each light emitting unit of the light emitting unit.   The double-sided light emitting device according to any one of claims 1 to 4, wherein the first reflecting material of each of the light emitting units is individually provided.   The double-sided light emitting device according to any one of claims 1 to 4, wherein the first reflector of each of the light emitting units is provided in common.   The double-sided light emitting device according to claim 5, wherein the first reflector is made of metal.   The double-sided light emitting device according to any one of claims 5 to 7, wherein the common frame is made of metal.   The double-sided light emitting device according to claim 8, wherein a second reflector is provided on a side surface of the light guide plate of each light emitting unit of the light emitting unit.

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