JP4866230B2 - Double-sided light emitting surface light source element and liquid crystal display device using the same - Google Patents

Description

  The present invention relates to a liquid crystal display device capable of displaying on both front and back surfaces used for a mobile phone, a guidance display board, an advertising signboard, an emergency light, and the like, and a surface light source element capable of emitting light on both sides.

  Surface light source elements (backlights) are required for liquid crystal display devices widely used in mobile phones, portable information terminals, personal computers, game machines, and the like. In particular, in the above-mentioned applications, there is a potential demand for thinning the liquid crystal display device. Therefore, a light guide type surface light source element in which a light source such as a cold cathode tube or a light emitting diode (LED) is arranged on the side surface of the light guide plate. It is usual to use. Recently, a liquid crystal display device in which liquid crystal display panels are arranged back to back on both sides of a housing like a mobile phone has been increasing. In general, this liquid crystal display device uses two sets of surface light source elements back to back as disclosed in Patent Document 1. However, since the number of parts is large, there are problems that the number of assembling steps increases, the thickness of the mobile phone increases, and further the cost increases.

  As another liquid crystal display device in which a liquid crystal display panel is disposed on both sides, a guidance display board, an advertising signboard, an emergency light, and the like can be given. In these liquid crystal display devices, it is common to use two sets of surface light source elements and liquid crystal display panels.

  Patent Document 2 proposes a method of emitting light on both sides by performing scattering printing on both surfaces of a single light guide plate in order to solve the problems such as increase in the number of assembly steps, increase in thickness, and cost increase. However, in this method, the scattering portion printed on the surface of the light guide serving as the light emitting surface acts as a light shielding portion, which causes a detrimental effect that the light use efficiency is reduced.

  Also, a light source is provided on the side surface of the light guide plate, a uniform layer and a diffusion plate are provided on the upper and lower surfaces of the light guide plate, and a reflective layer is formed in the light guide plate at a position shifted from the horizontal center position. Yes (Patent Document 3). According to this method, the amount of light emitted to the upper surface and the lower surface can be adjusted by the position of the reflective layer, but in principle, only a surface light source element having a light emitting area of the same size on both the upper and lower surfaces can be realized. Therefore, when the size of the liquid crystal display device on the upper surface and the lower surface is changed, it is necessary to take measures such as shielding unnecessary portions, so that a decrease in light utilization efficiency cannot be avoided.

  On the other hand, in patent document 4, the surface light source element which can light-emit on both sides is implement | achieved by closely_contact | adhering the emitted light control board in which several convex part was provided in the upper and lower surfaces of a light-guide plate. According to this method, although a very thin double-sided light emitting surface light source element can be obtained, the light from the light source disposed on the side surface of the light guide plate is distributed to the upper surface and the lower surface of the surface light source element. It is difficult to avoid, and therefore, there is a problem that the brightness is greatly reduced when light is transmitted through the liquid crystal display panel.

For the purpose of improving the light utilization efficiency in the liquid crystal display device, Patent Documents 5, 6 and 7 disclose reflective polarizers composed of alternating layers formed of different polymers. By disposing the reflective polarizer between the surface light source element and the liquid crystal display panel, linearly polarized light can be extracted from the random polarized light emitted from the surface light source element. Can be increased. However, since a light-reflective member such as a reflection sheet has to be used on the surface light source element side, it is generally used for a single-sided surface light source element.
JP-A-10-187075 JP 7-182914 A JP-A-6-243826 JP 2002-133906 A Japanese National Patent Publication No. 9-506837 Japanese National Patent Publication No. 9-506985 JP-T 9-507308

  The present invention has been made in view of the above problems, and a first object is to provide a double-sided light emitting surface light source element that can be thinned and has high light utilization efficiency. Moreover, this invention makes it the 2nd subject to provide the liquid crystal display device using this double-sided light emission surface light source element.

The first problem is a double-sided light emitting surface light source element having one light guide plate made of a transparent material and at least one light source disposed on a side surface of the light guide plate.
a) two outgoing light control plates formed with a plurality of convex portions respectively disposed on two opposing surfaces of the light guide plate; and b) respectively disposed on two opposing surfaces of the light guide plate. Comprising two polarization separation elements whose polarization transmission axes are orthogonal to each other;
The cross section of the convex portion of the outgoing light control plate has a parabolic shape, an elliptical shape, a trapezoidal shape, or a combination thereof, and the light guide plate, the outgoing light control plate, and the polarization separation element are in optical contact with each other. This is solved by obtaining a double-sided light emitting surface light source element characterized by being configured as described above.

  In the above-described double-sided light emitting surface light source element of the present invention, the two polarization separation elements are preferably disposed between the light guide plate and the outgoing light control plate.

  Also, in the double-sided light emitting surface light source element of the present invention, the two polarization separation elements are respectively disposed on the exit side surface of the exit light control plate that is optically in close contact with the two opposing surfaces of the light guide plate. It is preferable.

  Furthermore, in the double-sided light emitting surface light source element of the present invention, it is preferable that the polarization separation element is a non-absorption type polarization separation element.

  The second problem is solved by obtaining a liquid crystal display device having two liquid crystal display panels respectively disposed on both surfaces of the double-sided light emitting surface light source element according to the present invention.

  The liquid crystal display panel has polarizing plates on both sides of the liquid crystal cell, and the polarization transmission axis of the polarizing plate on the double-sided light emitting surface light source element side is the polarized light transmission of the polarization separating element of the corresponding double-sided light emitting surface light source element. It is preferable to coincide with the axis.

  According to the present invention, since the double-sided light emitting surface light source element can be realized with only one light guide plate, the thickness can be reduced. In addition, since the double-sided light-emitting surface light source element can emit linearly polarized light whose electric field vectors are orthogonal on different exit surfaces, high light utilization efficiency can be realized in a liquid crystal display device using a liquid crystal display panel.

  Hereinafter, the present invention will be described in detail with reference to the drawings. A schematic cross-sectional view of an example of the double-sided light emitting surface light source element of the present invention is shown in FIG. The double-sided light-emitting surface light source element includes a light source 1 composed of a cold cathode tube, an LED, and the like, a light guide plate 2 provided with the light source on a side surface, and light output from the light guide plate 2 and an emission angle of the extracted light. Output light control plates 31 and 32 for controlling the distribution of light. The emitted light control plates 31 and 32 are formed with a large number of convex portions 61 and 62, and the tips 41 and 42 of the convex portions 61 and 62 are optically formed on two opposing surfaces of the light guide plate 2. It is in close contact. Furthermore, polarization separation elements 71 and 72 described later are optically adhered to the double-sided light emitting surface light source element of the present invention. In FIG. 1, two polarization separation elements 71 and 72 whose polarization transmission axes are orthogonal to each other are in optical contact between the light guide plate 2 and the outgoing light control plates 31 and 32. As shown, the polarization separation elements 71 and 72 may be optically in close contact with the exit-side surfaces 51 and 52 of the outgoing light control plates 31 and 32 optically in close contact with the light guide plate and the convex portion.

In the present invention, the sectional shape of the convex portion of the outgoing light control plate needs to be a shape that allows the light taken into the convex portion to be totally reflected on the wall surface and obtain a desired outgoing light distribution . A shape made of a parabola, an ellipse, a trapezoid, or a combination thereof is used. In addition, the convex portion can have not only a one-dimensional pattern like a cylindrical lens but also a two-dimensional pattern like a microlens.

  The size of one convex portion represented by the length of the convex bottom portion is preferably 0.005 mm to 1.0 mm in view of display quality, ease of manufacture, and the like. Moreover, although the space | interval of a convex part is suitably selected according to the magnitude | size of a light emission area, the thickness of a light-guide plate, and the distance with an observer, it is suitable to exist in the range of 0.001 mm-5 mm. . Further, in order to make the in-plane luminance distribution of the light emitting surface constant, it is desirable to modulate in-plane so that the interval between the convex portions is large near the light source and the interval becomes small as the distance from the light source is increased.

  The light emission principle of the double-sided light emitting surface light source element of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing the locus of light rays in the double-sided light emitting surface light source element having the configuration shown in FIG. The arrows in the figure indicate the trajectories of the rays, and the linearly polarized light A and the linearly polarized light B, which are orthogonal to each other, of the electric field vector are represented by the symbols shown in the figure, respectively. Random polarization is shown. When the polarization separation element 71 on the upper surface of the double-sided light emitting surface light source element is arranged so that the linearly polarized light B is transmitted, the linearly polarized light B out of the random polarized light is extracted to the outgoing light control plate 31. On the other hand, the linearly polarized light A is reflected by the polarization separation element 71. Accordingly, only the linearly polarized light B is extracted from the upper outgoing light control plate 31. Further, when the polarization separation element 72 on the lower surface is arranged so that the linearly polarized light A is transmitted, only the linearly polarized light A is extracted from the random polarized light at the convex portion of the outgoing light control plate 32. On the other hand, the linearly polarized light B is reflected at the interface between the light guide plate and the polarization separation element 72. In addition, the random polarized light incident on the region where the convex portion does not exist in the outgoing light control plate is repeatedly extracted in the light guide plate without being taken out by the outgoing light control plate. For the reasons as described above, by disposing the two polarization separation elements 71 and 72 whose polarization transmission axes are orthogonal to each other as in the present invention on the opposite exit surface side of the light guide plate, from one exit surface, Only the linearly polarized light A is obtained, and only the linearly polarized light B is obtained from the other exit surface. In the example of FIG. 3, the linearly polarized light A and the linearly polarized light B are specularly reflected because they represent a reflective polarizer as the polarization separating element, but the linearly polarized light A is used when a scattering polarizer is used as the polarization separating element. Needless to say, the linearly polarized light B is scattered and reflected. In the present invention, either polarization separation element can be used.

  Next, the light emission principle of the double-sided light emitting surface light source element having the configuration shown in FIG. 2 will be described with reference to FIG. Random polarized light propagating through the light guide plate 2 is extracted by the convex portion 61 of the outgoing light control plate 31, reflected by the wall surface of the convex portion, and then reaches the interface between the outgoing light control plate 31 and the polarization separation element 71. At this time, when the polarization separation element 71 is arranged so that the linearly polarized light B is transmitted, only the linearly polarized light B out of the random polarized light is emitted to the outside, and the linearly polarized light A is reflected at the interface. The reflected linearly polarized light A enters the interface between the outgoing light control plate 32 and the polarization separation element 72 on the opposite surface. If the polarization separation element 72 is arranged so that the linearly polarized light A is transmitted at this time, the linearly polarized light A is emitted to the outside. In addition, the random polarized light incident on the region where the convex portion does not exist in the outgoing light control plate is repeatedly extracted within the light guide plate without being taken out by the outgoing light control plate. For the above reasons, only linearly polarized light A is obtained from one exit surface, and only linearly polarized light B is obtained from the other exit surface.

  The contact portion between the top of the convex portion of the outgoing light control plate and the light guide plate or the polarization separation element needs to be optically in close contact with the outgoing light control plate in order to extract light. In order to make such close contact, UV curable adhesives, hot melt adhesives, pressure-sensitive adhesives, double-sided tapes, and the like are selected and used, or a direct bonding method such as a melt-bonding method. This can be realized by using

  The liquid crystal display device 9 shown in FIG. 5 can be realized by disposing different liquid crystal display panels on the exit surface sides of the above-described double-sided light emitting surface light source element. Although this example uses the double-sided light emitting surface light source element of FIG. 1, it is also possible to use the double-sided light emitting surface light source element of FIG. In the liquid crystal display panel 81, it is necessary to make the polarization transmission axis of the polarizing plate 811 on the double-sided light emitting surface light source element side coincide with the polarization transmission axis of the corresponding polarization separation element 71. Similarly, in the liquid crystal display panel 82, the polarization transmission axes of the polarizing plate 821 on the double-sided light emitting surface light source element side and the polarization separating element 72 must be matched. However, in both liquid crystal display panels, the polarization transmission axes of the polarizing plates 812 and 822 on the side that is not the double-sided light emitting surface light source element depend on the liquid crystal display mode of the liquid crystal display panel. May coincide with or be orthogonal to the polarization transmission axes of the polarization separating elements 71 and 72.

  Although not shown here, in the liquid crystal display panel, the polarizing plates 811 and 821 on the double-sided light emitting surface light source element side may not be used. This is because linearly polarized light is emitted from the double-sided light emitting surface light source element of the present invention, and a good image can be displayed without using the polarizing plates 811 and 821. According to this configuration, it is possible to reduce the thickness and cost of the liquid crystal display device.

  For the reasons described above, it can be seen that the double-sided light emitting surface light source element of the present invention and the liquid crystal display device using the same have higher light utilization efficiency than the prior art. That is, by using the double-sided light emitting surface light source element of the present invention, random polarized light emitted from the light source can be emitted as linearly polarized light, and in the liquid crystal display device of the present invention, light is not lost in the liquid crystal display panel. This is because it can be used effectively.

  As the polarization separation element of the present invention, it is preferable to use a non-absorption type polarizer other than the absorption type. In other words, linearly polarized light is selectively transmitted from random polarized light, and the linearly polarized light is called a reflective polarizer or a scattering polarizer having a function of reflecting or scattering linearly polarized light whose electric field vectors are orthogonal. preferable. Examples include DBEF and DRPF from Sumitomo 3M Limited. Further, a wire grid type polarizer or a photonic crystal can be used.

  In the double-sided light emitting surface light source element of the present invention, the light emitting areas on the front and back surfaces can be the same or different sizes. That is, if the outgoing light control plates disposed on the front and back surfaces of the light guide plate are the same size, the light emitting areas are equal on both sides. On the other hand, different light emitting areas can be realized by changing the sizes of the outgoing light control plates on the front and back surfaces. This is because light can be extracted only from the portion where the convex portion of the outgoing light control plate is in optical contact with the light guide plate. Therefore, it is very suitable to use the double-sided light emitting surface light source element of the present invention for a liquid crystal display device that requires a main display and a sub display such as a mobile phone.

  Any light source can be used as long as it can irradiate the side surface of the light guide plate, such as a cold cathode tube, a hot cathode tube, and an LED, as a light source for making light incident on the side surface of the light guide plate. The light source may be disposed directly on the side surface of the light guide plate, or a member such as an optical waveguide may be interposed between the light source and the light guide plate. The light source in the present invention may be disposed only on one side as shown in FIG. 1 or may be disposed on two opposite side surfaces. Furthermore, you may arrange | position on four surfaces except the output side surface of a light-guide plate. Moreover, you may arrange | position a light source only to a corner part instead of the whole side surface of a light-guide plate.

  As the light guide plate used in the double-sided light emitting surface light source element of the present invention, a resin having excellent transparency such as acrylic resin, polycarbonate resin, polystyrene resin, cyclic olefin resin, or glass processed into a predetermined shape can be used. . However, in the present invention, since the polarization state of light propagating through the light guide plate must not be changed, a material having a small birefringence must be used. Therefore, acrylic resin is particularly suitable among the materials described above in the present invention. Moreover, as a processing method of this light-guide plate, the method of cutting out from an extrusion plate or a cast board, melt molding methods, such as a hot press and injection molding, etc. are used suitably.

  The convex shape of the outgoing light control plate can be obtained by using a concave mold such as a stamper, a female mold, or a roll mold, by a photopolymerization molding method using ultraviolet irradiation, an injection molding method using a thermoplastic resin, an extrusion molding method, or the like. However, since the polarization state of the light propagating through the outgoing light control plate must not be changed, it is particularly preferable to use an ultraviolet curable resin having a small birefringence. The concave mold used at this time can be produced, for example, by coating a negative or positive photosensitive resin on a glass substrate, exposing and developing the photosensitive resin through a photomask, and performing electroforming. However, it can also be directly engraved by cutting a metal plate.

  Examples and comparative examples are shown below.

Example 1
An outgoing light control plate used for a double-sided light emitting surface light source element was produced by the following procedure. A positive resist was spin-coated on a glass substrate, and exposure and development were performed through a photomask on which an arbitrary pattern was drawn. The uneven shape of the resist thus obtained is designed to be the convex shape of the outgoing light control plate required for the double-sided light emitting surface light source element, and nickel electroforming is applied to the concave and convex shape. Thus, a nickel stamper for the outgoing light control plate can be manufactured. In addition, since the arrangement | sequence of this convex part can be adjusted with the light-shielding pattern drawn on this photomask, in Example 1, the magnitude | size of a convex part bottom part is 0.02 mm, and the space | interval of a convex part is 0.03 mm- It was set to 0.8 mm. Moreover, the cross-sectional shape of this convex part was made into the trapezoid of height 0.02 mm, and the solid which rotated this with the central axis was made into the convex part of Example 1. FIG.

  Next, an ultraviolet curable resin (UVX4370: manufactured by Toagosei Co., Ltd.) obtained by adding an ultraviolet polymerization initiator to an acrylate monomer and an acrylate oligomer is poured into the nickel stamper, and “Arton” (57 mm × 75 mm × 0.1 mm) ( (Registered trademark) film (manufactured by JSR Corporation) was laminated. Furthermore, the ultraviolet curable resin was cured by irradiating a predetermined amount of ultraviolet rays from the arton film. Next, the nickel stamper and the arton film were peeled off to obtain a 57 mm × 75 mm × 0.2 mm emission light control plate having a plurality of convex portions formed on the surface. In the same procedure, an outgoing light control plate having the same shape and size was produced.

  Next, a 67 mm × 85 mm × 0.8 mm PMMA cast plate (“Paraglass” (registered trademark): manufactured by Kuraray Co., Ltd.) was used as the light guide plate, and a 0.01 mm thick acrylate-based ultraviolet curable adhesive layer (UVX4332: It was bonded to the top of the convex portion of the emitted light control plate via Toagosei Co., Ltd.). At this time, the two outgoing light control plates were bonded to the two opposing surfaces of the light guide plate, respectively.

  Subsequently, a polarization separation element was bonded to the surface of the outgoing light control plate via an adhesive layer having a thickness of 0.05 mm (SK Dyne: manufactured by Soken Chemical Co., Ltd.). In Example 1, two reflective polarizers (DBEF: manufactured by Sumitomo 3M Co., Ltd.) of 57 mm × 75 mm × 0.13 mm are used as the polarization separation elements, and the polarization transmission axes of the polarization separation elements are orthogonal to each other. As shown in the figure, they were respectively bonded to the outgoing light control plates on the front and back surfaces.

  Finally, by arranging four LEDs (NACW008: manufactured by Nichia Corporation) on one side surface (67 mm side) of the light guide plate at equal intervals, a double-sided light emitting surface light source element having a total thickness of 1.58 mm Could get.

A current of 30 mA was applied to each LED of the double-sided light emitting surface light source element to cause the double-sided light emitting surface light source element to emit light. When the front luminance at the center of the double-sided light emitting surface light source element was measured using a color luminance meter (BM-7A: manufactured by Topcon Corporation), both sides were 2000 cd / m ² .

(Comparative Example 1)
A 57 mm × 75 mm × 0.2 mm outgoing light control plate was produced in the same procedure as in Example 1, and a 67 mm × 85 mm × 0.8 mm PMMA cast plate (as used in Example 1) was used as the light guide plate. It was bonded to both sides of the same) via a 0.01 mm thick acrylate-based UV curable adhesive layer (same as used in Example 1). In Comparative Example 1, the polarization separation element is not used together.

  Next, the same four LEDs as those used in Example 1 are arranged at equal intervals on one side surface (side of 67 mm) of the light guide plate to obtain a double-sided light emitting surface light source element having a total thickness of 1.22 mm. I was able to.

A current of 30 mA was applied to each LED of the double-sided light emitting surface light source element to cause the double-sided light emitting surface light source element to emit light. When the front luminance at the center of the double-sided light emitting surface light source element was measured using a color luminance meter, both sides were 2000 cd / m ² .

  Comparing the results of Example 1 and Comparative Example 1, the front luminance of the surface light source element of Comparative Example 1 is equivalent to that of Example 1, whereas Comparative Example 1 emits randomly polarized light, Since linearly polarized light is emitted in the first embodiment, the light utilization efficiency of the first embodiment is higher when the liquid crystal display panel is used in combination.

(Example 2)
An outgoing light control plate used for a double-sided light emitting surface light source element was produced in the same procedure as in Example 1. However, the sizes of the outgoing light control plates were 36 mm × 45 mm × 0.2 mm and 20 mm × 16 mm × 0.2 mm, respectively. In both the outgoing light control plates, the size of the bottom of the convex portion was 0.02 mm, and the interval between the convex portions was adjusted to 0.03 mm to 0.8 mm. Moreover, the cross-sectional shape of this convex part was made into the trapezoid of height 0.02mm, and the solid which rotated this about the central axis was made into the convex part.

  Next, a 46 mm × 55 mm × 0.8 mm PMMA cast plate (same as in Example 1) was used as the light guide plate, and the polarization separation element was bonded via a 0.05 mm thick adhesive layer. In Example 2, a 36 mm × 45 mm × 0.13 mm and 20 mm × 16 mm × 0.13 mm scattering polarizer (DRPF: manufactured by Sumitomo 3M Limited) was used as the polarization separation element. The light guide plates were bonded to the front and back surfaces so that the polarization transmission axes were orthogonal to each other.

  Subsequently, the two outgoing light control plates described above were bonded to the surface of the polarization separation element via an acrylate-based ultraviolet curable adhesive layer (same as Example 1) having a thickness of 0.01 mm. In addition, the size of the outgoing light control plate to be bonded and the polarization separating element was the same.

  Finally, the same four LEDs used in Example 1 are arranged at equal intervals on one side surface (55 mm side) of the light guide plate to obtain a double-sided light emitting surface light source element having a total thickness of 1.58 mm. I was able to.

A current of 30 mA was applied to each LED of the double-sided light emitting surface light source element to cause the double-sided light emitting surface light source element to emit light. When the front luminance of the double-sided light emitting surface light source element was measured using the color luminance meter used in Example 1, the central portion of the light emitting area of 36 mm × 45 mm was 3000 cd / m ² and 20 mm × 16 mm in size. The central part of the light emitting area was 2000 cd / m ² .

  Furthermore, a liquid crystal display device was manufactured by mounting two sets of TN mode liquid crystal display panels on the double-sided light emitting surface light source element. In addition, the polarization transmission axis of the polarizing plate on the double-sided light emitting surface light source element side in the liquid crystal display panel was set in the same direction as the polarization transmission axis of the corresponding polarization separation element of the double-sided light emitting surface light source element. When image information was displayed on the liquid crystal display device, a bright and good image could be visually recognized on both the liquid crystal display devices.

(Comparative Example 2)
A 46 mm × 55 mm × 0.8 mm PMMA cast plate (same as Example 1) was used as the light guide plate, and white dot printing was performed on both sides by screen printing. The sizes of the print areas were 36 mm × 45 mm and 20 mm × 16 mm, respectively. Furthermore, on the light guide plate, one 0.14 mm diffusion sheet (PC-YBS: manufactured by Eiwa Co., Ltd.) having the same size as the printing area, and a prism sheet (BEFIII: Two sheets (manufactured by Sumitomo 3M Limited) were placed on each surface.

  Finally, the same four LEDs used in Example 1 are arranged at equal intervals on one side surface (55 mm side) of the light guide plate to obtain a double-sided light emitting surface light source element having a total thickness of 1.68 mm. I was able to.

A current of 30 mA was applied to each LED of the double-sided light emitting surface light source element to cause the double-sided light emitting surface light source element to emit light. When the front luminance of the double-sided light emitting surface light source element was measured using a color luminance meter, the central part of the light emitting area with a size of 36 mm × 45 mm was 2500 cd / m ² , and the central part of the light emitting area with a size of 20 mm × 16 mm was It was 1000 cd / m ² . In addition, it turned out that the surface which gave the white dot printing of 20 mm x 16 mm emitted light also from the area | region which has not performed this white dot printing, and has lost light greatly.

  Furthermore, a liquid crystal display device was manufactured by mounting two sets of TN mode liquid crystal display panels on the double-sided light emitting surface light source element. When image information was displayed on the liquid crystal display device, only a dark and unclear image could be seen on both liquid crystal display devices.

It is a schematic sectional drawing which shows the double-sided light emission surface light source element of this invention. It is a schematic sectional drawing which shows the double-sided light emission surface light source element of another example of this invention. It is a figure which shows the locus | trajectory of the light ray in the double-sided light emission surface light source element of this invention. It is a figure which shows the locus | trajectory of the light ray in the double-sided light emission surface light source element of another example of this invention. It is a schematic sectional drawing which shows the liquid crystal display device of this invention.

Explanation of symbols

1: Light source 2: Light guide plate 31: Emission light control plate 41: Incident surface 51: Light emitting surface 61: Convex portion 71: Polarization separation element 81: Liquid crystal display panel 811: Double-sided light emitting surface Light source element side polarizing plate 812: Double-sided light emission Polarizing plate 9 on the side other than the surface light source element side: liquid crystal display device

Claims (6)

In a double-sided light emitting surface light source element having one light guide plate made of a transparent material and at least one light source disposed on a side surface of the light guide plate,
a) two outgoing light control plates formed with a plurality of convex portions respectively disposed on two opposing surfaces of the light guide plate; and b) respectively disposed on two opposing surfaces of the light guide plate. Comprising two polarization separation elements whose polarization transmission axes are orthogonal to each other;
The cross section of the convex portion of the outgoing light control plate has a parabolic shape, an elliptical shape, a trapezoidal shape, or a combination thereof, and the light guide plate, the outgoing light control plate, and the polarization separation element are in optical contact with each other. A double-sided light emitting surface light source element characterized by being configured as described above.   The double-sided light emitting surface light source element according to claim 1, wherein the two polarization separation elements are respectively disposed between the light guide plate and the outgoing light control plate.   The said two polarization splitting elements are each arrange | positioned by the outgoing light side surface of the said outgoing light control board each optically closely_contact | adhered to the two surfaces which the said light-guide plate opposes, respectively. Double-sided light emitting surface light source element.   The double-sided light-emitting surface light source element according to claim 1, wherein the polarization separation element is a non-absorption type polarization separation element.   5. A liquid crystal display device comprising two liquid crystal display panels respectively disposed on both surfaces of the double-sided light emitting surface light source element according to claim 1.   The liquid crystal display panel has polarizing plates on both sides of the liquid crystal cell, and the polarization transmission axis of the polarizing plate on the double-sided light emitting surface light source element side is the polarized light transmission of the polarization separating element of the corresponding double-sided light emitting surface light source element. The liquid crystal display device according to claim 5, wherein the liquid crystal display device coincides with an axis.

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