JP5320713B2 - Double-sided light emitting surface light source device and liquid crystal display device using the same - Google Patents

Description

  The present invention relates to a double-sided light emitting surface light source device corresponding to a main liquid crystal panel and a sub liquid crystal panel, and further relates to a liquid crystal display device incorporating the double-sided light emitting surface light source device.

  In recent years, liquid crystal display devices having features such as light weight, thinness, and low power consumption are widely used as display devices for information devices such as personal computers and word processors, and display devices for video devices such as televisions, video movies, and car navigation systems. . In many cases, such a liquid crystal display device adopts a configuration in which a backlight unit (surface light source device) for applying illumination light from behind the liquid crystal panel is incorporated in order to realize a bright display screen.

  Here, the backlight unit is classified into an edge light system and a direct system according to the location of the light source. For example, the edge light system is a system in which a point light source device such as an LED is disposed on the edge of a light guide plate facing a liquid crystal panel. The direct method is a method in which a plurality of straight tubular light sources such as fluorescent discharge tubes are arranged on the back surface of the liquid crystal panel, and a diffusion plate is arranged between the liquid crystal panel and the light source. Among these methods, the edge light method is advantageous in terms of thinning, and can be said to be a method suitable for a display device of a portable electronic device such as a mobile phone or a notebook personal computer.

  By the way, for example, the usage forms of mobile phones are diversified, and mobile phones including a main liquid crystal and a sub liquid crystal are widely used in order to cope with various usages (see, for example, Patent Document 1). ). For example, in a folding mobile phone, the main liquid crystal display is used in the opened state, and information such as incoming mail is confirmed by the sub liquid crystal in the closed state. In addition, mobile phones with cameras are used in such a way that both the main liquid crystal and the sub liquid crystal are used separately depending on the case where the user or the other person is photographed.

For this reason, the backlight for the main side and the sub side is also required for the backlight having the irradiation function of the liquid crystal display unit. In this case, if the main liquid crystal and the sub liquid crystal are irradiated on each side using two backlights, an increase in thickness and an increase in the number of parts are inevitable. Double-sided light-emitting backlights that illuminate the sub-side simultaneously are becoming mainstream.
JP 2005-202058 A

  As described above, the double-sided light emitting backlight has a function of simultaneously illuminating two liquid crystal panels (main liquid crystal panel and sub liquid crystal panel) with one backlight, but the main liquid crystal and the sub liquid crystal have different sizes. There is a big problem that the outline of the sub liquid crystal panel is visually recognized when the liquid crystal panel is viewed. In order to make the outline of the sub liquid crystal invisible from the main liquid crystal panel side, for example, it has been attempted to arrange a large number of optical sheets. However, for this reason, there is a problem that the number of members is increased and an assembling man-hour is required. Newly occurs. Further, in the above-described liquid crystal display device, it is required to ensure the luminance of both the main liquid crystal panel and the sub liquid crystal panel. However, when a large number of optical sheets are arranged, there is a disadvantage that the luminance is lowered.

  The present invention has been proposed in view of such a conventional situation, and the outline of the sub liquid crystal is not visually recognized, and sufficient luminance is ensured not only in the main liquid crystal panel but also in the sub liquid crystal panel. It is another object of the present invention to provide a double-sided light emitting surface light source device and a liquid crystal display device that can minimize the increase in the number of parts and the number of man-hours.

In the double-sided light emitting surface light source device of the present invention , a main liquid crystal panel is disposed on one side of a light guide plate that irradiates light from a light source from both sides, and a sub-area having a smaller area than the main liquid crystal panel is provided on the other side. A double-sided light emitting surface light source device in which a liquid crystal panel is disposed, wherein a selective reflection polarizing sheet is disposed on a surface of the light guide plate on a sub liquid crystal panel side, and an antireflection sheet is disposed on the selective reflection polarizing sheet. The selective reflection polarizing sheet is also arranged on the main liquid crystal panel side, and the selective reflection polarizing sheet on the main liquid crystal panel side has a polarization axis on the sub liquid crystal panel side. The light guide plate is arranged so as to be substantially orthogonal to the polarization axis, and on the surface of the light guide plate on the sub liquid crystal panel side, a diffusion sheet, a light collecting sheet, a transfer prevention sheet, the selective reflection polarizing sheet, Preventing sheet has been stacked toward the light guide plate in that order, wherein the surface roughness of the light focusing sheet is disposed toward the transfer prevention sheet side.

  The liquid crystal display device of the present invention has a main liquid crystal panel and a sub liquid crystal panel, and has the above-described double-sided light emitting surface light source device incorporated therein.

  By disposing the antireflection sheet on the sub liquid crystal panel side of the light guide plate, the state in which the outline of the sub liquid crystal panel cannot be visually recognized from the main liquid crystal panel side is maintained, and the display quality is improved. As the structure of the double-sided light emitting surface light source device and the liquid crystal display device, it is only necessary to add an antireflection sheet, so that the increase in the number of parts and the increase in the number of steps can be minimized.

The effect is drastically improved by combining the antireflection sheet and the selective reflection polarizing sheet, and a significant increase in luminance is also realized. The invention of the present application is characterized in that the optical sheet group includes a first selective reflection polarizing sheet in which a condensing sheet and a reflective polarizing sheet are integrated.

  According to the present invention, the outline of the sub liquid crystal is not visually recognized, the luminance of the main liquid crystal panel and the sub liquid crystal panel can be improved, and the increase in the number of parts and the increase in the number of man-hours are minimized. It is possible to provide a double-sided light emitting surface light source device and a liquid crystal display device that can be used.

  Hereinafter, a double-sided light emitting surface light source device according to the present invention and a liquid crystal display device using the same will be described.

  FIG. 1 shows a basic configuration of a double-sided light emitting surface light source device (backlight unit) 1 to which the present invention is applied. As shown in FIG. 1, the backlight unit 1 of the present embodiment includes an LED chip 2 that is a point light source device, a light guide plate 3, and optical sheet groups 4 and 5 arranged on both surfaces of the light guide plate. The light from the LED chip 2 which is a point light source is converted into a surface light source by the light guide plate 3. Here, the light incident on the light guide plate 3 is emitted from both surfaces of the light guide plate 3, and is thus configured as a double-sided light emitting backlight.

  The main liquid crystal side and the sub liquid crystal side of the light guide plate 3 are respectively supported by the frames 6 and 7 of the liquid crystal display device, but the area of the opening 6a of the frame 6 on the main liquid crystal side is the frame 7 on the sub liquid crystal side. It is larger than the area of the opening 7a. This is because the display area of the main liquid crystal panel is larger than the display area of the sub liquid crystal panel.

  Further, on the sub liquid crystal side, an antireflection sheet 8 having an opening corresponding to the opening 7a of the frame 7 on the sub liquid crystal side is disposed on the optical sheet group 5, and the contour of the sub liquid crystal is formed from the main liquid crystal side. I try to prevent it from being visible. As the antireflection sheet 8, for example, a black sheet or a film with an antireflection coating can be used.

As described above, the display area of the main liquid crystal panel is larger than the display area of the sub liquid crystal panel. Therefore, if no countermeasure is taken, light is transmitted through the opening 7a of the frame 7 on the sub liquid crystal side, and light is reflected by the frame 7 in other portions. As a result, there is a difference in the amount of light returning to the main liquid crystal side between the sub liquid crystal part and the other part, and the outline of the sub liquid crystal may be seen when viewing the display from the main liquid crystal side. In contrast, by disposing the antireflection sheet 8, the amount of light returning to the main liquid crystal side of the opening 7a and the other parts of the frame 7 is substantially equal, but glare sub LCD contour to the main LCD Reduced.

The sub LCD contour reflection of, in addition to the installation of the anti-reflection sheet 8, it is possible to further improved by devising the structure of the optical film group 4,5. The optical sheet groups 4 and 5 are designed in consideration of light uniformity, efficient irradiation, and the like, and are composed of, for example, a plurality of optical sheets combined with a diffusion sheet, a light collecting sheet, and the like.

  The diffusion sheet plays a role of diffusing and uniformizing the light transmitted through the light guide plate 3. For example, a film in which light diffusion particles are dispersed in a light-transmitting resin film is used. . As the resin film, for example, a film such as polyethylene terephthalate or polycarbonate is used.

  The light collecting sheet is also referred to as a prism sheet or a lens sheet, and plays a role of improving the luminance by condensing light in one direction, and is a film having a form in which prisms having a light collecting function are arranged. is there. The light from the light guide plate 3 is aligned in a predetermined direction (a direction substantially orthogonal to the film surface) by the light collecting sheet, and the light is efficiently irradiated. As a result, the luminance is improved.

  In order to eliminate the reflection of the outline of the sub liquid crystal and improve the luminance, it is effective to use a so-called selective reflection polarizing sheet. In particular, by using a selective reflection polarizing sheet as a component of the optical sheet group 5 on the sub liquid crystal side, the reflection of the contour of the sub liquid crystal on the main liquid crystal is reduced, and the luminance of the sub liquid crystal panel is also improved.

The selective reflection polarizing sheet is also called a brightness enhancement sheet, a polarizing reflection sheet, a polarization separation sheet, or the like, and a plurality of types are known depending on the film configuration. For example, as shown in FIG. 2A, it is possible to use a first selective reflection polarizing sheet 9A in which a prism film portion 9a and a reflective polarizing film 9b are integrated. Here, the prism film portion 9a has the same form and function as those of the previous light-collecting sheet, and contributes to improvement in luminance. The reflective polarizing film has been developed based on reflective polarizing technology, and plays a role of reflecting a part of light from the light source (LED chip 2) and returning it to the main liquid crystal panel side. As the selective reflection polarizing sheet 9A, a commercially available film can be used. Specific examples include, for example, a product name DBEF manufactured by Sumitomo 3M Limited.

  Alternatively, it is also possible to use a selective reflection polarizing sheet 9B as shown in FIG. The selective reflection polarizing sheet 9B has a configuration in which a prism film portion 9c is added to the reflective polarizing film 9b side of the selective reflection polarizing sheet 9A described above, and has a larger luminance improvement effect than the selective reflection polarizing sheet 9A. As the selective reflection polarizing sheet 9A, a commercially available film can be used. Specifically, for example, trade name BEFRP manufactured by Sumitomo 3M Limited can be used.

  By using these selective reflection polarizing sheets 9A and 9B, it is possible to reduce the number of parts compared to the case where a prism film (light collecting sheet) and a reflective polarizing film are used separately, and a double-sided light emitting surface light source This is useful for simplifying and thinning the device, and further for simplifying and thinning the liquid crystal display device.

  The selective reflection polarizing sheets 9A and 9B are used in combination with an optical sheet such as a diffusion sheet or a light collecting sheet. In this case, the optical sheet to be combined is arbitrary. FIG. 3 shows a configuration example in which the selective reflection polarizing sheet 9A (selective reflection polarizing sheet A) and various optical sheets are combined. FIG. 4 shows a configuration example in which the selective reflection polarizing sheet 9B (selective reflection polarizing sheet B) and various optical sheets are combined.

  For example, in the configuration example shown in FIG. 3A, a diffusion sheet, a light collecting sheet, a light collecting sheet, a transfer prevention sheet, a selective reflection polarizing sheet A, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, A diffusion sheet, a condensing sheet, and a condensing sheet are stacked on the main liquid crystal side. In the above configuration example, the optical sheet group 5 is constituted by five optical sheets from the diffusion sheet on the sub liquid crystal side to the selective reflection polarizing sheet A, and the optical sheet group 4 is constituted by three optical sheets on the main liquid crystal side. Will be.

  Similarly, in the configuration example shown in FIG. 3B, a diffusion sheet, a diffusion sheet, a light collecting sheet, a transfer prevention sheet, a selective reflection polarizing sheet A, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, A diffusion sheet, a condensing sheet, and a condensing sheet are stacked on the main liquid crystal side. In the above configuration example, the optical sheet group 5 is constituted by five optical sheets from the diffusion sheet on the sub liquid crystal side to the selective reflection polarizing sheet A, and the optical sheet group 4 is constituted by three optical sheets on the main liquid crystal side. The

  In the configuration example shown in FIG. 3C, a diffusion sheet, a light collecting sheet, a light collecting sheet, a transfer prevention sheet, a selective reflection polarizing sheet A, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the main liquid crystal is arranged. A diffusion sheet and a condensing sheet are stacked on the side. In the configuration example shown in FIG. 3D, a diffusion sheet, a condensing sheet, a transfer prevention sheet, a selective reflection polarizing sheet A, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet is arranged on the main liquid crystal side. The light collecting sheets are stacked. In the configuration example shown in FIG. 3E, a diffusion sheet, a light collecting sheet, a transfer prevention sheet, a selective reflection polarizing sheet A, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet is arranged on the main liquid crystal side. The light collecting sheet and the light collecting sheet are arranged in a stacked manner.

  Regardless of which sheet configuration is employed, the reflection of the contour of the sub liquid crystal on the main liquid crystal is reduced, and the luminance of the sub liquid crystal panel is improved. When the selective reflection polarizing sheet A is used, it is necessary to interpose a transfer preventing sheet between the light collecting sheet and this is for the following reason.

In the case where the selective reflection polarizing sheet A is used, if the light is directly superimposed on the light collecting sheet, the unevenness on the surface of the light collecting sheet is transferred to the back side (the reflective polarizing film 9b portion) of the selective reflection polarizing sheet A, resulting in uneven brightness. This may cause In the selective reflection polarizing sheet A, the reflective polarizing film portion 9b is soft, and the surface unevenness of the condensing sheet is easily transferred. Therefore, by interposing a transfer prevention sheet between the light-condensing sheet with selective reflective polarizing sheet A, it is necessary to prevent the transfer of the surface irregularity of the condensing sheet.

  As the transfer prevention sheet, for example, a diffusion sheet or the like can be used. By interposing these transfer prevention sheets, the condensing sheet is not directly in contact with the back surface of the selective reflection polarizing sheet A, and the transfer of the surface irregularities can be performed. It is surely prevented. The diffusion sheet is made of polyethylene terephthalate, polycarbonate, or the like, and the surface unevenness is hardly transferred even when it contacts the light collecting sheet. Even if the surface unevenness of the light collecting sheet is transferred to the diffusion sheet, the diffusion sheet has a light diffusing effect, so that there is no influence of luminance unevenness or the like. In addition, although the sheet | seat of arbitrary thickness can be used for the transcription | transfer prevention sheet distribute | arranged between a condensing sheet | seat and the selective reflection polarizing sheet A, when thinning of the double-sided light emission surface light source device 1 is considered as much as possible. It is preferable to use a thin sheet.

  On the other hand, the configuration example shown in FIG. 4 is an example using the selective reflection polarizing sheet B. For example, in the configuration example shown in FIG. 4A, a diffusion sheet, a condensing sheet, and a selective reflection are provided on the sub liquid crystal side of the light guide plate. The polarizing sheet B and the antireflection sheet are stacked and the diffusion sheet, the light collecting sheet, and the light collecting sheet are stacked on the main liquid crystal side. In the above configuration example, the optical sheet group 5 is constituted by three optical sheets from the diffusion sheet on the sub liquid crystal side to the selective reflection polarizing sheet B, and the optical sheet group 4 is constituted by three optical sheets on the main liquid crystal side. Will be.

  Similarly, in the configuration example shown in FIG. 4B, a diffusion sheet, a diffusion sheet, a selective reflection polarizing sheet B, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet, the collector is arranged on the main liquid crystal side. A light sheet and a light collecting sheet are stacked. In the configuration example shown in FIG. 4C, a diffusion sheet, a condensing sheet, a selective reflection polarizing sheet B, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet and the condensing sheet are arranged on the main liquid crystal side. Are arranged in layers. In the configuration example shown in FIG. 4D, a diffusion sheet, a selective reflection polarizing sheet B, and an antireflection sheet are stacked on the sub liquid crystal side of the light guide plate, and a diffusion sheet and a light collecting sheet are stacked on the main liquid crystal side. doing. In the configuration example shown in FIG. 4E, a diffusion sheet, a selective reflection polarizing sheet B, and an antireflection sheet are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet, the light collection sheet, and the light collection sheet are arranged on the main liquid crystal side. Are arranged in layers.

  Even when the selective reflection polarizing sheet B is used, the reflection of the contour of the sub liquid crystal on the main liquid crystal is reduced regardless of which sheet configuration is employed, and the luminance of the sub liquid crystal panel is improved. Further, the number of parts (the number of optical sheets) can be reduced as compared with the case where the selective reflection polarizing sheet A is used.

  The double-sided light emitting surface light source device having the above configuration is incorporated as a backlight unit in a liquid crystal display device. Next, a liquid crystal display device incorporating the above-described double-sided light emitting surface light source device will be described.

  FIG. 5 shows a schematic configuration of a liquid crystal display device incorporating a double-sided light emitting surface light source device (backlight unit). As shown in FIG. 5, the liquid crystal display device of the present embodiment includes a main liquid crystal panel 11, a sub liquid crystal panel 12, and the above-described surface light source device 1, and the periphery thereof is held by a resin frame 13 and integrated. It tries to become.

  The main liquid crystal panel 11 and the sub liquid crystal panel 12 are configured by enclosing a liquid crystal material between the array substrates 11a and 12a and the counter substrates 11b and 12b, respectively. The array substrates 11a and 12a have pixels corresponding to display pixels. Electrodes and switching elements (thin film transistors) are formed in a matrix. In addition, on the array substrates 11a and 12a, a signal line for sending an electric signal to the pixel electrode and a gate line for supplying a switching signal to the thin film transistor which is a switching element are wired orthogonally to each other. On the other hand, on the opposing substrates 11b and 12b, the opposing electrodes are formed on almost the entire surface with a transparent electrode material (for example, ITO), and a color filter layer is formed corresponding to each pixel. Further, polarizing plates 14, 15, 16, and 17 are bonded to the outer surfaces of the array substrates 11a and 12a and the counter substrates 11b and 12b, respectively, with their polarization axes orthogonal to each other.

  The main liquid crystal panel 11 and the sub liquid crystal panel 12 are mounted with an LSI for supplying a drive signal (here, only the LSI 18 of the sub liquid crystal panel 12 is shown), and the above-mentioned is based on the drive signal from the external circuit board. The switching element is driven to display an image. A region where this image display is performed is a display region, and the main liquid crystal panel 11 and the sub liquid crystal panel 12 have a display region in which a large number of pixels are arranged.

The double-sided light emitting surface light source device 1 used as a backlight unit irradiates light from the back side of the main liquid crystal panel 11 or the sub liquid crystal panel 12 to make the display on the main liquid crystal panel 11 or the sub liquid crystal panel 12 bright and easy to see. Is. As described above, as described above, the light guide plate 3 for irradiating the light from the LED chip 2 as the light source to the back surfaces of the main liquid crystal panel 11 and the sub liquid crystal panel 12, and the light guide plate 3 an optical sheet group 4 disposed between the main liquid crystal panel 11, an optical sheet group 5 and antireflection sheet 8 disposed between the light guide plate 3 and the sub liquid crystal panel 12. The LED chip 2 that is a light source is provided along at least one side of the light guide plate 3.

  The frame 13 is formed of a resin material or the like, and is formed with a main liquid crystal accommodating portion 13 a that constitutes an accommodating space for the main liquid crystal panel 11 and a sub liquid crystal accommodating portion 13 b that constitutes an accommodating space for the sub liquid crystal panel 12. The main liquid crystal accommodating portion 13a is formed to support the periphery of the main liquid crystal panel 11, and the sub liquid crystal accommodating portion 13b is formed with an opening 13c corresponding to the display area of the sub liquid crystal panel 12. .

  Light emitted from the LED chip 2 that is a light source is guided to the light guide plate 3, passes through the light guide plate 3 and the optical sheet group 4, and is then irradiated to the main liquid crystal panel 11. Similarly, after passing through the light guide plate 3 and the optical sheet group 5, the sub liquid crystal panel 12 is irradiated. In the main liquid crystal panel 11 and the sub liquid crystal panel 12, the irradiated light is transmitted, and images such as characters and videos are displayed with a predetermined brightness.

In the liquid crystal display device of the present embodiment, the antireflection sheet 8 to the sub-liquid crystal side as described above is arranged, more selective reflective polarizing sheet A as the optical sheet of the optical sheet group 4, B is used Therefore, the outline of the sub liquid crystal panel 12 is not seen from the main liquid crystal panel 11 side. Further, in the liquid crystal display device of the present embodiment, it is only necessary to change the configuration of the optical sheet group 5, and an increase in the number of parts and man-hours can be minimized.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this embodiment, A various change is possible. For example, it is possible to further eliminate the reflection of the outline of the sub liquid crystal panel 12 by disposing the selective reflection polarizing sheet A on the main liquid crystal side in addition to the sub liquid crystal side.

  In this case, it is preferable to arrange the polarization axis of the selective reflection polarizing sheet A on the main liquid crystal side so as to be orthogonal to the polarization axes of the selective reflection polarizing sheets A and B on the sub liquid crystal side. Further, the selective reflection polarizing sheet A can be integrally formed on the polarizing plate 14 of the main liquid crystal panel 11. In this case, a hard coat may be applied to the surface.

  Hereinafter, specific examples of the present invention will be described based on experimental results.

  A double-sided light emitting surface light source device having the configuration shown in FIGS. 3 and 4 was manufactured, and the luminance measurement and the state of visual recognition of the sub liquid crystal frame from the main liquid crystal side were examined. The configuration shown in FIG. 3 (a) is shown in Example 1, the configuration shown in FIG. 3 (b) is shown in Example 2, the configuration shown in FIG. 3 (c) is shown in Example 3, and the configuration shown in FIG. 3 (d). Example 4, the configuration shown in FIG. 3 (e) is shown in Example 5, the configuration shown in FIG. 4 (a) is shown in Example 6, and the configuration shown in FIG. 4 (b) is shown in Example 7 and FIG. 4 (c). The configuration is shown in Example 8, the configuration shown in FIG. 4D is Example 9, and the configuration shown in FIG. As the selective reflection polarizing sheet A, a product name DBEF manufactured by Sumitomo 3M Limited was used, and as the selective reflection polarizing sheet B, a product name BEFRP manufactured by Sumitomo 3M Limited was used.

  For comparison, a double-sided light emitting surface light source device (Comparative Example 1 to Comparative Example 3) having a sheet configuration shown in FIGS. 6A to 6C was also produced, and the same measurement was performed on these devices. In Comparative Example 1, that is, in the configuration example shown in FIG. 6A, a diffusion sheet, a condensing sheet, a condensing sheet, a transfer prevention sheet, and a selective reflection polarizing sheet A are stacked on the sub liquid crystal side of the light guide plate. A diffusion sheet, a light condensing sheet, and a light condensing sheet are stacked on the main liquid crystal side. In the configuration example shown in Comparative Example 2, that is, FIG. 6B, the diffusion sheet, the light collecting sheet, and the selective reflection polarizing sheet B are arranged on the sub liquid crystal side of the light guide plate, and the diffusion sheet and the light collecting are arranged on the main liquid crystal side. Sheets and condensing sheets are stacked. In Comparative Example 3, that is, in the configuration example shown in FIG. 6C, a transflective sheet (white sheet) is disposed on the sub liquid crystal side of the light guide plate, and a diffusion sheet, a light collecting sheet, and a light collecting sheet are disposed on the main liquid crystal side. Sheets are stacked.

  Measurements were made on the brightness of the main liquid crystal panel, the brightness of the sub liquid crystal panel, the main / sub brightness comparison (the brightness ratio of the sub liquid crystal panel when the brightness of the main liquid crystal panel is 100%), and the sub liquid crystal panel from the main liquid crystal side. The liquid crystal frame is visible. The visual status of the sub liquid crystal frame is x when the sub liquid crystal frame is visible from the main liquid crystal side, Δ when the sub liquid crystal frame is visible from the main liquid crystal side but slightly, and the sub liquid crystal frame is almost visible from the main liquid crystal side. The case where it was not visible was marked as ◯. The results are shown in Table 1.

  As is clear from Table 1, in each example in which the antireflection sheet and the selective reflection polarizing sheet are arranged on the sub liquid crystal side, the sub liquid crystal frame is not seen from the main liquid crystal side, and the luminance of the sub liquid crystal panel is sufficient. Secured. On the other hand, in Comparative Examples 1 and 2 in which the selective reflection polarizing sheet is arranged without the antireflection sheet, the luminance of the sub liquid crystal panel is improved, but the sub liquid crystal frame is slightly from the main liquid crystal side. I could see it. In Comparative Example 3 in which a transflective sheet (white) was disposed on the sub liquid crystal side, the sub liquid crystal frame was not seen from the main liquid crystal side, but the luminance of the sub liquid crystal panel was greatly reduced.

It is a schematic sectional drawing which shows the arrangement | positioning state of the component of a double-sided light emission surface light source device. It is a figure which shows the structure of a selective reflection polarizing sheet, (a) shows the structure of the selective reflection polarizing sheet A, (b) shows the structure of the selective reflection polarizing sheet B. (A)-(e) is a figure which shows the structural example using the selective reflection polarizing sheet A. FIG. (A)-(e) is a figure which shows the structural example using the selective-reflection polarizing sheet B. FIG. It is sectional drawing which shows schematic structure of a liquid crystal display device. (A)-(c) is a figure which shows the structure of Comparative Examples 1-3.

1 double-sided light emitting surface light source device,
2 LED chips,
3 light guide plate,
4,5 optical sheet group,
7 Sub LCD frame, 7a Frame opening ,
8 Antireflection sheet,
9, 9A, 9B, A, B selective reflection polarizing sheet,
9a Prism film part, 9b Reflective polarizing film,
11 Main LCD panel,
12 Sub LCD panel,
13 frames,
14, 15, 16, 17 Polarizing plate

Claims (4)

A double-sided light emitting surface light source in which a main liquid crystal panel is disposed on one side of a light guide plate that irradiates light from the light source from both sides, and a sub-liquid crystal panel having a smaller area than the main liquid crystal panel is disposed on the other side A device,
A selective reflection polarizing sheet is arranged on the surface of the light guide plate on the sub liquid crystal panel side, and an antireflection sheet is arranged on the sub liquid crystal panel side on the selective reflection polarizing sheet,
The selective reflection polarizing sheet is also disposed on the main liquid crystal panel side, and the selective reflection polarizing sheet on the main liquid crystal panel side has a polarization axis substantially orthogonal to the polarization axis of the selective reflection polarizing sheet on the sub liquid crystal panel side. Arranged,
On the surface of the light guide plate on the sub liquid crystal panel side, a diffusion sheet, a light collecting sheet, a transfer prevention sheet, the selective reflection polarizing sheet, and an antireflection sheet are stacked in this order toward the light guide plate. And a light emitting device having a double-sided light emitting surface, wherein the surface irregularities of the condensing sheet are arranged toward the transfer-preventing sheet.   The selective reflection polarizing sheet disposed on the surface of the light guide plate on the side of the sub liquid crystal panel is formed by integrating a prism film portion and a reflective polarizing film, and the prism film portions are respectively provided on the front and back sides of the reflective polarizing film. The double-sided light emitting surface light source device according to claim 1, comprising: The light source is an LED, and is disposed opposite to the end face of the light guide plate, and a sub liquid crystal side frame that contacts the antireflection sheet is disposed, and corresponds to the opening of the sub liquid crystal side frame. 3. The double-sided light emitting surface light source device according to claim 1, wherein the antireflection sheet having an opening is disposed. The light source is an LED, and is disposed opposite to the end face of the light guide plate, and a sub liquid crystal side frame that contacts the antireflection sheet is disposed, and corresponds to the opening of the sub liquid crystal side frame. The antireflection sheet having an opening is arranged,
A main liquid crystal panel and a sub liquid crystal panel, wherein the main liquid crystal side and the sub liquid crystal side of the light guide plate are respectively supported by the frame of the liquid crystal display device, and the area of the opening of the frame on the main liquid crystal side is that of the frame on the sub liquid crystal side the liquid crystal display device characterized by that the double-sided light emitting surface light source device of any one claim wherein from claim 1, wherein 3 is incorporated an larger than the area of the opening.

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