JP2005106959A - LCD module - Google Patents

Abstract

Disclosed is a transmissive liquid crystal display module in which a reduction in display quality due to a gap between a liquid crystal display element and a backlight is reliably prevented, and a good display quality can be stably obtained.
A liquid crystal display element Lc in which a front polarizing plate 3 and a rear polarizing plate 4 are installed on both front and back surfaces of a liquid crystal cell C, and a sidelight type surface light source device La including a light guide plate 5 and a cold cathode tube 6 are provided. A surface layer in which the reflective polarizing sheet 11, the λ / 4 retardation film 12 and the light diffusing sheet 13 are laminated and a composite optical sheet layer Os is interposed between the reflective polarizing sheet 11 and the reflective polarizing plate 11 of the rear polarizing plate 4. Is an anti-glare treatment layer 4a having a uniform uneven surface, and is uniformly point-contacted with the surface of the reflective polarizing plate 11. This prevents the occurrence of a non-uniform contact state in which the surface of the rear polarizing plate 4 and the reflective polarizing sheet 11 are partially in surface contact, and the boundary between the surface contact region and the non-contact region around it is display visibility. The problem of lowering is eliminated.
[Selection] Figure 2

Description

  The present invention relates to a liquid crystal display module including a surface light source device that emits light in a planar shape using a light guide plate.

  2. Description of the Related Art Conventionally, as a backlight of a transmissive liquid crystal display device, a sidelight type surface light source device in which light source light is incident from an end surface of a light guide plate and light is emitted in a planar shape from one main surface is used. In this side light type surface light source device, the light incident from the end surface is diffusely reflected by the main surface opposite to the light emitting surface and emitted from the light emitting surface. As shown also in the prior art 1 (see FIG. 1), it is formed on a smooth surface.

  Therefore, when the above-described sidelight type surface light source device is installed in a liquid crystal display element in which polarizing plates are arranged on the front side and the rear side on the observation side of the display of the liquid crystal cell, the smooth light emitting surface of the light guide plate and The normally flat surface of the liquid crystal display element comes into contact with the entire or part of the polarizing plate surface.

  As described above, when the smooth surfaces partially contact each other, the contact area is in a completely intimate state without an air layer, and the non-contact area around it is a gap space where an air layer exists. Further, the boundary between both optically different regions is easily recognized visually from the observation side, and the display quality is remarkably deteriorated.

In many cases, an appropriate number of optical sheets are interposed between the light guide plate and the liquid crystal display element in order to suppress loss of light emitted from the light guide plate and to make the intensity distribution uniform. However, if the surface of the optical sheet in contact with the rear polarizing plate surface is smooth, the same problem occurs. When the optical sheet is an optical element that generates interference fringes (moire) such as a prism sheet, the moire further reduces the display quality.
JP 2003-167251 A

  The present invention reliably prevents a deterioration in display quality due to a gap between the liquid crystal display element and the backlight, even though the surface light source device using the light guide plate is a backlight, and stably provides a good display quality. It is an object to provide a transmissive liquid crystal display module that can be obtained.

  In order to solve the above problems, the liquid crystal display module of the present invention has a front side which is a viewing side of a liquid crystal cell formed by sandwiching liquid crystal between a pair of substrates, and a rear side opposite to the front side. A liquid crystal display element in which a front polarizing plate and a rear polarizing plate are respectively disposed, a light source, and light emitted from the light source is incident, and the rear polarization is made from a light exit surface opposed to the rear polarizing plate of the liquid crystal display element. A liquid crystal display module having a backlight composed of a light guide plate that emits light toward the plate, wherein the surface of the rear polarizing plate facing the light output surface of the light guide plate is a uniform uneven surface This is a liquid crystal cell.

  According to the liquid crystal display module of the present invention, by making the surface of the rear polarizing plate a uniform concavo-convex surface, the surface of the rear polarizing plate and the light emitting surface or the optical sheet surface of the light guide plate opposed to and in contact with the surface are made uniform. It is possible to reliably prevent the occurrence of defects in which a surface contact area is partially generated and the boundary between the surface contact area and the surrounding non-contact area is visually recognized. Can be obtained.

  In the liquid crystal display module of the present invention, a concavo-convex coat layer made of a material in which fine particles having a substantially uniform particle size are dispersed and mixed in a base resin liquid is laminated on one surface of a polarizing element as a rear polarizing plate. It is preferable to use an anti-glare polarizing plate formed by the above method, and this makes it possible to easily manufacture a polarizing plate having an uneven surface with a uniform surface.

  An optical sheet for making the intensity distribution of the light emitted from the light guide plate uniform between the rear polarizing plate and the light exit surface of the light guide plate and efficiently making the light incident on the rear polarizing plate while suppressing loss of the emitted light. Therefore, it is possible to prevent not only the boundary between the surface contact area and the non-contact area between the rear polarizing plate and the optical sheet but also the occurrence of moire caused by the optical sheet, and the luminance distribution can be reduced. It is possible to easily obtain a transmissive liquid crystal display module having a uniform and improved display quality.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is an exploded perspective view showing a transmissive liquid crystal display module as an embodiment of the present invention, and FIG. 2 is a schematic sectional view thereof.

  A liquid crystal cell C is formed by sandwiching a liquid crystal layer (not shown) between the pair of transparent glass substrates 1 and 2. In the liquid crystal cell C, a front polarizing plate 3 is installed on the outer surface opposite to the surface (hereinafter referred to as the inner surface) that sandwiches the liquid crystal layer of the front glass substrate 1 that serves as the display viewing side. A rear polarizing plate 4 is installed on the outer surface of the rear glass substrate 2 to configure a liquid crystal display element Lc.

  Here, the surface of the rear polarizing plate 4 is formed in a uniform uneven surface. In the present embodiment, a uniform uneven surface is obtained by so-called anti-glare treatment. That is, as shown in FIG. 3, a hard coat in which silicic acid fine powder having a uniform particle size is dispersed and mixed in one surface of a polarizing film 4a having a transmission axis and an absorption axis in directions orthogonal to each other. By applying the mixed liquid, the anti-glare hard coat layer 4b having a uniform uneven surface is formed.

  Returning to FIG. 2, a sidelight type surface light source device La is arranged behind the rear polarizing plate 4. The side light type surface light source device La includes a tapered transparent light guide plate 5 having a substantially wedge-shaped cross section, and a cold cathode tube 6 as a light source disposed opposite to an end surface 5a as a light incident surface of the light guide plate 5. The reflector 7 is arranged so as to surround the cold cathode tube 6 and reflects the light emitted from the cold cathode tube 6 to the light incident surface 5a, and the light emission surface 5b opposite to the liquid crystal cell C of the light guide plate 5 The light reflecting plate 8 facing the surface, and the light reflecting film 9 deposited on the end surface of the light guide plate 5 opposite to the light incident surface 5a. Here, the opposite light exit surface 5c of the light guide plate 5 opposite to the light exit surface 5b is alternately formed with two types of inclined surfaces 5c1, 5c2 extending in parallel to the longitudinal direction of the light incident surface 5a and having different inclination angles. The cross section formed continuously is formed on an uneven surface having a sawtooth shape. The sidelight type surface light source device La configured as described above is housed in the box-type case 10 having an open upper surface with the light emitting surface 5b of the light guide plate 5 facing up.

  Between the light exit surface 5b of the light guide plate 5 and the rear polarizing plate 4, a reflective polarizing sheet 11 for improving the luminance, a λ / 4 phase difference film 12, and a light diffusion sheet 13 for making the luminance distribution uniform. A composite optical sheet layer Os is laminated. The composite optical sheet layer Os is interposed such that the reflective polarizing sheet 11 is in contact with the surface of the anti-glare hard coat layer 4 b of the rear polarizing plate 4 and the diffusion sheet 13 is in contact with the light exit surface 5 b of the light guide plate 5. Yes.

  Here, the surface of the reflective polarizing sheet 11 that is opposed to the rear polarizing plate 4 is a smooth surface. However, since the surface of the polarizing plate 4 that is in contact with the back surface is a uniform uneven surface of the antiglare hard coat layer 4b, A uniform point contact state is obtained over the entire surface, and a non-uniform contact state in which a surface contact region is partially generated does not occur. Accordingly, in the display, the boundary between the partial surface contact area and the surrounding non-contact area is visually recognized, and the display quality is not deteriorated.

  In the liquid crystal display module configured as described above, the light emitted from the cold cathode tube 6 is reflected directly or reflected by the reflector 7 and enters the light incident surface 5a of the light guide plate 5, and the other part of the light guide plate 5 passes through the other side. While traveling toward the end face, the light enters the inclined surface 5c1 of the reflected light emitting surface 5c, and is either totally reflected or emitted to the outside here toward the light emitting surface 5b. The light emitted to the outside is reflected by the light reflecting plate 8, reenters the light guide plate 5, and travels toward the light emitting surface 5b.

  The light reflected toward the light emitting surface 5b is emitted in a planar shape from the light emitting surface 5b, but the distribution state and the light emitting direction at that time are uneven and have large variations. However, when the light is incident on the diffusion sheet 13 laminated on the light emitting surface 5b, the variation is made uniform. The planar light beam having a uniform light intensity distribution and emission direction passes through the next λ / 4 phase difference plate 12 and enters the reflective polarizing sheet 11. Of the light incident on the reflective polarizing sheet 11, the polarization component along the transmission axis is transmitted, and the polarization component along the reflection axis is linearly polarized and reflected again toward the light reflection plate 8. 1 round trip between During this time, the polarization direction of the linearly polarized light is rotated by 90 ° in order to pass through the λ / 4 retardation plate 12 twice, and the polarization direction becomes linearly polarized light along the transmission axis of the reflective polarizer 11. Therefore, the polarized component light also passes through the reflective polarizing sheet 11. In this way, almost all of the light incident on the reflective polarizing sheet 11 is transmitted as linearly polarized light along the reflection axis. Since the polarization direction in which the linearly polarized light is aligned is also along the transmission axis of the rear polarizing plate 4, almost all incident light passes through the rear polarizing plate 4 and enters the liquid crystal cell C.

  Therefore, according to the liquid crystal display module of the present embodiment, the ratio of the loss of the light source emitted from the cold cathode tube 6 to be diffused or absorbed is suppressed as much as possible to irradiate the liquid crystal display element Lc very efficiently. As a result, a display with high and uniform luminance can be obtained, and the boundary between the surface of the polarizing plate 4 and the surface of the reflective polarizing sheet 11 which is in contact with the polarizing plate 4 and the non-contact region around the surface can be visually recognized. In addition, the generation of moire caused by transmission through an optical sheet such as the reflective polarizing sheet 11 and the λ / 4 retardation plate 12 is prevented, and an extremely high quality transmissive display can be stably obtained. Can do.

  In addition, this invention is not limited to embodiment mentioned above. For example, the present invention can also be suitably applied to a case where the optical sheet is not directly interposed between the rear polarizing plate and the light guide plate on the backlight side and both are brought into direct contact with each other.

  Further, the light source of the backlight is not limited to a linear light source such as a cold cathode tube, but a point light source such as an LED (Light-emitting diode) can also be used.

It is a disassembled perspective view which shows one Embodiment of this invention. It is a typical sectional view showing the above-mentioned embodiment. It is a partial expanded sectional view which expands and shows the Q section in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Glass substrate 3 Front polarizing plate 4 Rear polarizing plate 5 Light guide plate 6 Cold cathode tube 11 Reflective polarizing sheet 12 λ / 4 retardation film 13 Light diffusion sheet Lc Liquid crystal display element La Sidelight type surface light source device

Claims (3)

A liquid crystal display in which a front polarizing plate and a rear polarizing plate are respectively arranged on the front side, which is a viewing side of the display of a liquid crystal cell having a liquid crystal sandwiched between a pair of substrates, and on the rear side opposite to the front side. Elements,
A backlight comprising: a light source; and a light guide plate that emits light from the light source and emits light toward the rear polarizing plate from a light emitting surface opposed to the rear polarizing plate of the liquid crystal display element. A liquid crystal display module,
A liquid crystal display module, wherein a surface of the rear polarizing plate facing the light exit surface of the light guide plate is a uniform uneven surface.   The rear polarizing plate is an anti-glare polarizing plate formed by laminating an uneven coat layer made of a material in which fine particles having a substantially uniform particle diameter are dispersed and mixed in a base resin liquid on one surface of a polarizing element. 2. The liquid crystal display module according to claim 1, wherein the liquid crystal cell is disposed in the liquid crystal cell in an arrangement in which the uneven coating layer is opposed to a light emitting surface of the light guide plate.   In order to make the intensity distribution of the light emitted from the light guide plate uniform between the rear polarizing plate and the light exit surface of the light guide plate, and to efficiently make the light incident on the rear polarizer while suppressing loss of the emitted light. The liquid crystal display module according to claim 1, wherein an optical sheet is interposed.

Images