JP4539463B2 - Surface illumination device and liquid crystal display module - Google Patents

Description

The present invention relates to a planar illumination device and a liquid crystal display module .

Conventionally, as a backlight of a flat panel display such as a liquid crystal display device, as disclosed in Patent Document 1, a light source is disposed opposite to an end surface of a light guide plate, and light emitted from the light source and incident from the opposite end surface is one side of the light guide plate. A sidelight type planar illumination device that emits in a planar shape from the main surface is suitably used.
JP-A-7-28060

  On the other hand, displays used for amusement devices such as various game machines are required to have a wide variety of displays in order to enhance their interest. To meet such demands, it is not enough to deal with various display images themselves, and it has been required to use optical characteristic distribution such as luminance distribution of backlight light itself as a display pattern.

  However, it has not been easy to obtain irradiation light having an intended optical characteristic distribution pattern by the sidelight type planar illumination device.

An object of the present invention is to provide a planar lighting device and a liquid crystal display module that can divide into a plurality of predetermined irradiation areas and irradiate irradiation lights having different luminances and enable various displays rich in interest. .

The planar device of the present invention includes a light guide plate that guides light incident from an end surface and emits the light from the first main surface, and a light source that emits light toward the end surface, and the light guide plate In the first region of the second main surface opposite to the first main surface, a plurality of luminance setting means are arranged so that the occupied area has a predetermined density, and the second main surface A plurality of brightness setting means in the second area such that the light quantity from the light source emitted from the second area is larger than the light quantity from the light source emitted from the first area; The grooves are arranged at a higher density than the region, and grooves along the boundary portion are provided at positions corresponding to the boundary portion between the first region and the second region.
The liquid crystal display module of the present invention includes a light guide plate that guides light incident from the end face and emits the light from the first main face toward the liquid crystal display panel, and a light source that emits light toward the end face. And the light guide plate has a plurality of luminance setting means arranged in a first area of the second main surface facing the first main surface so that an occupied area has a predetermined density, In the second region of the second main surface, a plurality of light amounts from the light source emitted from the second region are larger than light amounts from the light source emitted from the first region. The brightness setting means is disposed at a higher density than the first region, and a groove along the boundary is provided at a position corresponding to the boundary between the first region and the second region. It is a feature.
A liquid crystal display module according to another aspect of the present invention includes a light guide plate that guides incident light and emits the light from a main surface, and a prism that aligns an optical path of light emitted from the light guide plate in a predetermined direction. A prism unit between the light guide plate and a backlight unit having a sheet and an optical sheet that transmits one of the two linearly polarized light components of the light that has passed through the prism sheet and reflects the other. A liquid crystal display panel arranged so that the optical sheet is interposed in order, and the prism sheet and the optical sheet are a plurality of light beams emitted from the backlight unit. It is characterized in that it is arranged in another area so as to avoid at least one of the areas.

According to the present invention, it is possible to divide into a plurality of predetermined irradiation areas and irradiate irradiation lights having different luminances, thereby enabling various interesting displays.

  FIG. 1 is a schematic cross-sectional view showing a liquid crystal display module equipped with a planar illumination device as a first embodiment of the present invention. FIG. 2 is an exploded view of a surface emitting backlight unit as the planar illumination device. It is a disassembled perspective view shown.

  As shown in FIG. 1, the housing of the present liquid crystal display module includes a storage case 1 having a shape obtained by removing a top plate of a flat rectangular parallelepiped box, and a cover case 2 having the same shape from which a bottom plate has been removed. Being done. Both of these cases 1 and 2 are formed by processing a metal plate. A display window 2b for observing the display is formed in the top plate 2a of the cover case 2.

  A liquid crystal display panel 3 is housed in the uppermost part of the housing in which the cover case 2 is fitted into the housing case 1. In the liquid crystal display panel 3, a pair of glass substrates 4 and 5 on which electrodes (not shown) are formed are joined to each other with a predetermined gap by a frame-shaped sealing material 6 with their electrode formation surfaces facing each other. A liquid crystal 7 is sealed between opposing surfaces (hereinafter referred to as inner surfaces) of the glass substrates 4 and 5 surrounded by the sealing material 6. A pair of front and rear polarizing plates 8 and 9 are attached to the outer surfaces of the glass substrates 4 and 5, respectively. The liquid crystal display panel 3 of the present embodiment is an active matrix type liquid crystal display panel, and a plurality of pixel electrodes (not shown) are arranged in a matrix on the inner surface of one of the pair of glass substrates 4 and 5. On the inner surface of the other glass substrate opposite to this, a single film-like counter electrode (not shown) is provided.

  One glass substrate 5 of the glass substrates 4 and 5 has one edge portion extending outward from the corresponding end surface of the other glass substrate 4 to form an extension portion 5a. In the extended portion 5a, connection terminals (not shown) of the lead wires connected to the electrodes of the substrates 4 and 5 are arranged in parallel.

  A driving circuit element 10 for driving the liquid crystal 7 is directly mounted on the extending portion 5a in which the electrode wiring and the connection terminal row are formed by the COG (Chip On Glass) method. The flexible wiring board 11 is conductively joined to the edge of the extended portion 5a.

  A surface-emitting backlight unit 13 is installed via a spacer 12 on the rear side of the liquid crystal display panel 3 opposite to the display side. In this embodiment, a double-sided adhesive tape is used as the spacer 12, whereby a predetermined gap is secured between the liquid crystal display panel 3 and the surface emitting backlight unit 13 and both are fixed. ing.

  As shown in FIG. 2, the surface-emitting backlight unit 13 according to the present embodiment includes a light guide plate 14 having a rectangular planar outer shape, and an end surface of three sides excluding one short side of the light guide plate 14. The cold-cathode tube assembly 15 is arranged in a letter-like manner and the reflection sheet 16 is provided on the rear surface 142 of the light guide plate 14.

  Returning to FIG. 1, the light guide plate 14 is formed using a highly transparent resin material such as acrylic resin, and has an area in which the effective display area Ad of the liquid crystal display panel 3 is widened by a predetermined width over the entire circumference. On the rear surface 142 opposite to the front surface 141 on the liquid crystal display panel 3 side, minute convex portions (not shown) for reflecting light toward the front surface 141 are arranged and formed in a predetermined distribution pattern. ing. In the present embodiment, the rear surface 142 on which the minute protrusions are formed serves as a luminance setting unit for irradiation light.

  FIG. 3A is a plan view of the light guide plate 14 viewed from the rear surface 142 side, and FIG. 3B is a partial arrow view of the main part viewed from the Z direction. As shown in FIG. 3A, a groove 143 is formed on the rear surface 142 of the light guide plate 14 along a line that bisects the light guide plate 14 along the longitudinal direction. A plurality of convex portions 142a are arranged in the section S1 with a higher area occupancy than the section S2, and a plurality of convex portions 142b are arranged in the other section S2 with a lower area occupancy (see section S1). Hereinafter, the section S1 is referred to as a high area ratio section, and the section S2 is referred to as a low area ratio section).

  The convex portions 142a and 142b of the sections S1 and S2 in the present embodiment are both formed in a hemispherical shape as shown in FIG. 3B, and are arranged with substantially the same vertical and horizontal pitches p1 and p2. Has been. The diameter φ1 of each convex portion 142a of the high area ratio section S1 is in the range of 1.6 mm to 1.0 mm from the end portion on the side where the cold cathode tube 15a is not disposed to face the opposite end portion. It is set to gradually decrease. On the other hand, the diameter φ2 of each convex portion 142b of the low area ratio section S2 is 1.2 mm to 0.7 mm from the end portion on the side where the cold cathode tube 15a is not opposed to the opposite end portion. It is set so as to become gradually smaller in the range of.

  As a result, the area occupancy of each convex portion 142a in the high area ratio section S1 is approximately twice the area occupancy of each convex section 142b in the low area ratio section S2. As a result, the average luminance of the irradiation area corresponding to the high area ratio section S1 in the irradiation light emitted from the light guide plate front surface 141 is about twice the average luminance of the irradiation area corresponding to the low area ratio section S2. .

  Incidentally, the dimensions of the light guide plate 14 of the present embodiment are 140 mm and 210 mm in length and width, respectively, and the thickness T is 4 mm. With respect to such a light guide plate 14, the arrangement pitch of the convex portions 142a and 142b is as follows. The vertical pitch p1 is about 0.8 mm, the horizontal pitch p2 is about 1.7 mm, and the height H is set to about 0.2 mm at the convex portion 142a having the maximum diameter. In addition, each convex part 142a, 142b should be formed in the optimal shape according to the luminance distribution of the irradiation light to obtain, not only hemispherical but a truncated cone shape, a truncated pyramid shape, a cylindrical shape, etc. It is.

  The groove 143 is provided to reduce the width of the intermediate luminance area generated at the boundary between the high luminance irradiation area corresponding to the high area ratio section S1 and the low luminance irradiation area corresponding to the low area ratio section S2 in the irradiation light. The width W is preferably set within a range of 0.8 mm to 2.0 mm and the depth D within a range of 2 mm to 3 mm (1/2 to 3/4 of the light guide plate thickness T). In this embodiment, the width W is set to 1.0 mm and the depth D is set to 2 mm (T / 2). The groove 143 may be provided on the front surface 141 of the light guide plate 14. In this case as well, the effect of reducing the width of the intermediate luminance area can be obtained as in the case where the groove 143 is provided on the rear surface 142.

  Returning to FIG. 2, in the cold cathode tube assembly 15, harnesses 15 b and 15 b are electrically connected to the respective terminal electrodes at both ends of the U-shaped cold cathode tube 15 a, and each of the pair of harnesses 15 b and 15 b is connected. The other end is electrically connected to the connector 15c.

  The light reflecting sheet 16 installed on the rear surface 142 of the light guide plate 14 is formed by laminating the light scattering sheet 16b on the conductive sheet 16a, and the light scattering sheet 16b is installed facing the rear surface 142 of the light guide plate. The light reflecting sheet 16 of this embodiment uses a white PET (polyethylene terephthalate) sheet as the light scattering sheet 16b, and an aluminum foil sheet coated with an acrylic pressure-sensitive adhesive on one side as the conductive sheet 16a is bonded thereto. Do it.

  The light reflecting sheet 16 has a U-shaped cross section with the light scattering sheet 16b on the edge corresponding to the end faces of the three sides of the light guide plate 14 on which the cold cathode fluorescent lamps 15 are opposed. It is folded in. The cold cathode tube 15 is accommodated in the folding edge of the U-shaped cross section. As a result, the light emitted from the cold cathode tube 15 in the direction other than the opposite end surface side of the light guide plate 14 is reflected toward the opposite end surface by the light scattering sheet 16b on the inner surface side, and the electromagnetic wave emitted from the cold cathode tube 15 Noise is shielded by the outer conductive sheet 16a.

  The tongue 16c is formed by extending a part of the edge of the light reflecting sheet 16 that is not folded into the U-shape for an appropriate length. The tongue 16c is provided for grounding the light reflecting sheet 16 via the storage case 1.

  In the surface emitting backlight unit 13 configured as described above, the light emitted from the cold cathode fluorescent lamp 15a is reflected by the light scattering sheet 16b of the light reflecting sheet 16 directly or surrounding the light guide plate from the opposing end face. 14 is incident on the rear surface 142 of the convex / concave surface on which minute convex portions 142a and 142b (see FIG. 3) are formed, and is reflected toward the front surface 141, and the reflected light is reflected from the front surface 14a. The light is emitted in a planar shape.

  Note that there is also light that enters the uneven rear surface 142 and exits from the light guide plate 14. However, the emitted light is reflected by the light scattering sheet 16 b of the light reflection sheet 16 and enters the light guide plate 14 again. To do. Thereby, the utilization efficiency of the emitted light from the cold cathode tube 15a is remarkably enhanced.

  Returning to FIG. 1, the flat light-emitting panel including the light guide plate 14, the cold cathode tube 15, and the light reflecting sheet 16 described above is housed in a frame 17 that constitutes the casing of the surface light-emitting backlight unit 13. In this case, first, the light reflecting sheet 16 is dropped into the frame 17 and inserted in a manner, and then the light guide plate 14 is placed on the light scattering sheet 16b of the light reflecting sheet 16 and then bent into a U shape. A cold cathode tube 15 a that is a U-shape of the cold cathode tube assembly 15 is accommodated by raising the tip of the tube.

  The frame 17 is formed of, for example, an injection molding method or the like using a resin material on a box body including a rectangular bottom plate 17a corresponding to the planar outer shape of the light reflecting sheet 16 and side plates 17b erected on the four sides thereof. ing. In this way, by forming the frame 17 from a resin material having a low magnetic inductivity, a power loss that is lost through the frame 17 as a part of the high-voltage current supplied to the cold cathode tube 15 as a “leakage current” is avoided.

  The frame 17 is provided with an extraction hole 17c in the bottom plate 17a for extracting the tongue portion 16c of the light reflecting sheet 16 to the outside of the frame 17, and the extracted tongue portion is formed in the side plate 17b in the vicinity of the extraction hole 17c. An intake hole 17d is formed for folding back 16c and inserting it into the frame 17 again. The bottom plate 17a of the frame 17 is also provided with holes (not shown) through which the harnesses 15b and 15b of the cold cathode tube 15 are taken out of the frame 17.

  An optical sheet laminate 18 is installed on the front side of the light guide plate 14 housed in the frame 17. The optical sheet laminate 18 is formed by sequentially laminating a lower diffusion sheet 18 a, a prism sheet 18 b, and an upper diffusion sheet 18 c on the light exit surface 14 a of the light guide plate 14. As a result, the light emitted from the light emitting surface (front surface) 14a of the light guide plate 14 is planarized by the upper and lower diffusion sheets 18a and 18c, and the emission direction is changed by the prism sheet 18b. The light exit surface 14a is aligned in a substantially normal direction.

  A light cover case 19 made of a metal material is fitted to the frame 17 in which the light guide plate 14, the cold cathode tube 15, the light reflecting sheet 16, and the optical sheet laminate 18 are installed and housed as described above. The light cover case 19 includes a top plate 19a having a rectangular outer shape corresponding to the light guide plate 14, and side plates 19b provided on the four sides thereof. The top plate 19a receives the planar emitted light from the light guide plate 14. An irradiation window 19c for irradiating the rear surface of the liquid crystal display panel 3 is formed.

  When the light cover case 19 is fitted into the frame 17, the side plate 19b is placed between the outer side of the bent edge of the light reflecting sheet 16 (the surface of the conductive sheet 16a) and the inner side of the frame side plate 17b. To force insertion. As a result, the light cover case side plate 19b and the conductive sheet 16a on the back side of the light reflecting sheet 16 are in surface contact over a sufficiently large area, and the light cover case 19 and the light reflecting sheet 16 are reliably connected to each other.

  On the rear surface (outer surface) of the bottom plate 17a of the frame 17, an electronic circuit board 20 that controls driving of the entire liquid crystal display module is installed. The other end portion of the flexible wiring board 11 whose one end portion is conductively bonded to the substrate extension portion 5 a of the liquid crystal display panel 3 is conductively bonded to the electronic circuit board 20. A pair of harnesses 15b, 15b in the cold cathode tube assembly 15 are drawn out to the back side of the frame 17, and a connector 15c electrically connected to the other end of the harnesses 15b, 15b is provided on the electronic circuit board 20. Conductive installation is performed in a corresponding drive circuit unit (not shown). A spring contact 21 is conductively installed on the ground circuit 20 a provided on the electronic circuit board 20. The spring contact 21 is made of an elastic metal material such as beryllium copper, and a base portion 21b that supports the tip contact portion 21a is soldered to the ground circuit 20a.

  Here, the luminance distribution on the display surface of the liquid crystal display module configured as described above will be described in detail with reference to FIGS.

  As described above, the luminance distribution in the planar irradiation light emitted from the front surface 141 of the light guide plate 14 is a distribution corresponding to the area occupation ratio of the convex portions formed on the rear surface 142 of the light guide plate. Accordingly, the luminance distribution on the display surface of the liquid crystal display module is also a distribution corresponding to the area occupancy ratio of the convex portions formed on the rear surface 142 of the light guide plate.

Table 1 shown in FIG. 4A shows the luminance distribution measurement result on the display surface of the liquid crystal display module, and shows the luminance (unit: nt) at each measurement point shown in FIG. 4B. . Table 2 shown in FIG. 4C is a table showing the luminance distribution measurement result on the display surface when the groove 143 as a comparative example is not provided.

As apparent from Table 1, the average luminance in the display area A2 (hereinafter referred to as the low area ratio display area) including the positions 1 to 10 corresponding to the low area ratio section S2 (see FIG. 3) is 401.82 nt (cd / m ² ), the average luminance in the display area A 1 (hereinafter referred to as the high area ratio display area) including the positions 16 to 25 corresponding to the high area ratio section S 1 (see FIG. 3) is 632.93 nt, The average luminance of the high area ratio display area A1 is approximately 1.6 times higher than the average luminance of the low area ratio display area A2.

The luminance in the display area corresponding to the area where the grooves 143 are arranged, that is, the band-shaped display area extending from the center to the positions 11 to 15 is 650 to 850 nt, and the luminance at the corresponding position in the high area ratio display area A1. Higher than.

  Therefore, the luminance distribution of the display by the irradiation light emitted from the surface emitting backlight unit in this embodiment is the brightest in the area near the center line that bisects the entire display area along the longitudinal direction. The distribution is such that the high area ratio display area A1 and the low area ratio display area A2 having an average luminance ratio of 1.6: 1 are present in the same area.

Note that a bright line zone with high luminance (hereinafter referred to as a high luminance central zone) that appears in the area corresponding to the groove 143 of the light guide plate 14 described above is visually perceived by the observer as luminance unevenness, and there is a risk of lowering the display quality. . In order to reduce the expression of the high-brightness central band, the light reflecting sheet 51 is fitted into the groove 143 as shown in FIG. 5A, or the groove 143 as shown in FIG. A black light absorbing film 52 may be deposited on the upper bottom surface. When the reflective sheet 51 is fitted as in the former case, it has been confirmed that the luminance of the corresponding display area is reduced to 100 to 150 nt. In addition, when the light absorption film 52 is applied as in the latter case, a dark band with low luminance appears in the corresponding display area, but the dark band is less visible to the observer than the bright band, so the display quality is degraded. Less.

  On the other hand, if the groove 143 is not provided along the boundary line between the high area ratio section S1 and the low area ratio section S2 in the light guide plate 14, a luminance distribution as shown in Table 2 of FIG. That is, the luminance of the display area corresponding to the boundary line portion at positions 10 to 15 is a value in the middle range of each average luminance of the high area ratio display area A1 and the low area ratio display area A2, that is, 500 to 540 nt. However, since this intermediate luminance area extends with a width of about 10 mm along the boundary between the display areas A1 and A2, the display quality of the liquid crystal display module is significantly reduced as a result.

  The ratio of the average luminances of the high area ratio display area A1 and the high area ratio display area A2 on the display surface of this comparative example is about 1.8: 1, which is approximately 2: 1. As a result, the average luminance of the irradiation area corresponding to the high area ratio section S1 in the irradiation light emitted from the light guide plate front surface 141 is about twice the average luminance of the irradiation area corresponding to the low area ratio section S2. It shows that there is.

  As described above, in the liquid crystal display module of this embodiment, the rear surface 142 of the light guide plate is formed with the high area ratio section S1 in which the convex portions 142a having a large area are formed at the same pitch and the convex portions 142b having a small area. In accordance with this, the luminance distribution on the display surface using the irradiation light emitted from the front surface 141 as the backlight is high luminance corresponding to the high area ratio section S1. The distribution is composed of a high area ratio display area A1 and a low luminance low area ratio display area A2 corresponding to the low area ratio section S2. The ratio of the area occupancy ratios of the convex portions 142a and 142b of the high area ratio section S1 and the low area ratio section S2 is set to about 2: 1, and the groove 143 is formed along the boundary line between these sections. By providing the above, the average luminance ratio between the high luminance display area A1 and the low luminance display area A2 corresponding to each section can be made approximately 1.6: 1, and the boundary lines between the sections can be handled. Thus, the width of the uneven luminance area that appears in a strip shape can be reduced. As a result, on the display screen of the liquid crystal display module, it is possible to obtain a high-quality display that is diverse and amusing and does not visually recognize band-like luminance unevenness.

  Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected about the component same as the said 1st Embodiment, and the description is abbreviate | omitted.

  In the surface-emitting backlight unit of the present embodiment, the arrangement pattern of the convex portions provided on the rear surface 142 of the light guide plate 14 is a normal arrangement pattern for obtaining irradiation light with a uniform luminance distribution, and is obtained on the front surface 141. The shading process is performed corresponding to the luminance distribution of the irradiated light. As the shading processing method, a method of printing minute black dots, a method of arranging a light shielding film having a predetermined light transmittance in a predetermined pattern, and the like are preferably used.

  That is, as shown in FIG. 6, black dots 61 are arranged by printing at a predetermined density in one section obtained by equally dividing the light guide plate front surface 141 into two halves in the longitudinal direction. That is, in the present embodiment, the black dots 61 arranged in a predetermined pattern on the light guide plate front surface 141 serve as luminance setting means for obtaining irradiation light having a plurality of irradiation areas having different luminances. The arrangement density and blackness of the black dots 61 in this case are set so that transmission of about half the amount of light emitted from the light guide plate 14 to the liquid crystal panel side can be blocked.

  Thereby, the luminance distribution of the emitted irradiation light becomes a distribution in which the luminance of the half area corresponding to the black dot arrangement section is reduced to ½ of the luminance of the other half area. As a result, although the average luminance of the entire irradiation light is reduced as compared with the case of the above embodiment, the expression of the intermediate luminance area at the boundary between the low luminance area and the high luminance area is substantially eliminated. And, in a liquid crystal display panel using illumination light having such a luminance distribution pattern as backlight light, although the brightness decreases because the amount of light is reduced, there is an intermediate luminance area at the boundary between display areas with different luminance. A good display that does not appear is obtained.

  Next, a third embodiment of the present invention will be described with reference to FIG. Also in this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the surface-emitting backlight unit of this embodiment, the arrangement pattern of the protrusions provided on the rear surface 142 of the light guide plate 14 is a normal arrangement pattern for obtaining irradiation light with a uniform luminance distribution, and is installed on the front surface 141. The configuration of the optical sheet laminate is made to correspond to the luminance distribution of the irradiation light to be obtained.

  That is, in the present embodiment, the optical sheet laminate 70 installed on the front side of the light guide plate 14 has a deflection prism sheet 72 and a brightness enhancement film sheet 73 on the same light diffusion sheet 71 as the lower light diffusion sheet 18a of the first embodiment. And are laminated. The deflecting prism sheet 72 and the brightness enhancement film sheet 73 have their installation zones corresponding to the brightness distribution of the irradiation light to be obtained. That is, the brightness setting means in this embodiment is the deflecting prism sheet 72 and the brightness enhancement film sheet 73 that are selectively arranged, and each of the sheets 72 and 73 divides the light guide plate front surface 141 into two equal parts along the longitudinal direction. Are superimposed on the light diffusion sheet 71 so as to correspond to the sections.

  The deflecting prism sheet 72 is an optical sheet formed on a concavo-convex surface in which a plurality of protrusions 72a whose cross section forms a right triangle on one surface is continuously arranged in parallel to the longitudinal direction of the sheet. The extending direction of 72 a, that is, the sheet longitudinal direction is set parallel to the longitudinal direction of the light guide plate 14, and the rear surface on the side opposite to the concavo-convex surface is disposed on the light diffusing sheet 71.

  The brightness enhancement film sheet 73 is an optical sheet having a transmission axis 73a and a reflection axis 73b orthogonal to each other in the plane as optical axes, and the transmission axis 73a is 45 ° with respect to a center line c along the sheet longitudinal direction. Crossed. This brightness enhancement film sheet 73 has its transmission axis 73a intersected with the extending direction (sheet longitudinal direction) of the protrusion 72a of the deflecting prism sheet 72 at about 45 °, and the front surface (uneven surface) of the deflecting prism sheet 72. It is superposed on.

  In the surface-emitting backlight unit of this embodiment, the transmission axis 73a of the brightness enhancement film sheet 73 is positioned parallel to the transmission axis 9a of the rear polarizing plate 9 of the liquid crystal display panel 3 with respect to the liquid crystal display panel 3. It is installed by arrangement.

  In the liquid crystal display module in which the surface emitting backlight unit of the present embodiment configured as described above is installed, the light emitted from the light guide plate front surface 141 is diffused when passing through the light diffusion sheet 71, Of the diffused light, the light transmitted through the deflecting prism sheet 72 arranged in the following order is subjected to the deflecting action when transmitted, and the traveling direction is roughly the normal direction (the front direction of the display screen of the liquid crystal display module). It is aligned and emitted.

  The outgoing light whose traveling direction is aligned with the front direction is incident on the next brightness enhancement film sheet 73, and the polarization component light having the polarization plane along the transmission axis 73a is transmitted as it is, and along the reflection axis 73b. The polarized component light having the polarized plane is reflected. In FIG. 1, the polarized component light reflected on the side opposite to the liquid crystal display panel 3 side (rear side) is reflected by the light reflecting sheet 16 installed on the rear surface 142 of the light guide plate, and again the brightness enhancement film sheet. Re-enters 73 and is reflected back again. In this way, while the polarization component light reflected by the brightness enhancement film sheet 73 is repeatedly reflected from the light reflection sheet 16, a polarization component having a polarization plane along the transmission axis 83a is generated. The polarized component light along the transmission axis 83a passes through the brightness enhancement film sheet 73.

  As a result, the irradiation light emitted from the surface-emitting backlight unit toward the liquid crystal display panel is the luminance of the irradiation light in the area corresponding to the section where the deflection prism sheet 72 and the brightness enhancement film sheet 73 are laminated. The transmission film 73a of the enhancement film sheet 73 and the polarization plane are parallel to each other and linearly polarized light with enhanced brightness (light quantity) is obtained, and the irradiation light in the remaining half area is diffused light that is not polarized. And the brightness | luminance in the display surface of the liquid crystal display panel which this irradiation light entered via the back polarizing plate 9 is the average brightness | luminance of the display area corresponding to the division on which the deflection | deviation prism sheet 72 and the brightness enhancement film sheet 73 were laminated | stacked, About 2.0 to 2.3 times higher than the average luminance of the remaining half of the display area.

  Note that the number of deflecting prism sheets is not limited to one, and two deflecting prism sheets may be provided. In that case, the extending directions of the protrusions may be arranged to be orthogonal to each other. By adopting such a configuration, the average luminance of the half display area corresponding to the section in which the brightness setting means formed by laminating the two prism sheets and the brightness enhancement film sheet is arranged, and the remaining half of the display area. Is about 2.3 to 2.5 times higher than the average luminance.

  As described above, the surface-emitting backlight unit of the present embodiment is an optical sheet stack composed of a deflection prism sheet and a brightness enhancement sheet as brightness setting means for obtaining irradiation light having a plurality of areas each having different brightness. Since the body is selectively arranged on the light emitting surface 141 side of the light guide plate 14, irradiation light with high luminance with the polarization direction substantially aligned in a predetermined direction can be obtained in the corresponding area. That is, on the display surface of the liquid crystal display panel 3 in which the illumination light having a plurality of areas having different luminances is used as the backlight light, the display area corresponding to the arrangement section of the optical sheet laminate composed of the deflection prism sheet and the luminance enhancement sheet. A luminance distribution pattern in which the average luminance is enhanced approximately twice or more than the average luminance of other display areas is obtained. As a result, by changing the arrangement section of the optical sheet laminate, a variety of displays composed of a plurality of areas with different luminance can be obtained, and the light loss can be suppressed, so that the overall brightness is improved. A high-quality display is obtained in which no band-like luminance unevenness is visually recognized in the boundary area corresponding to the boundary portion.

Note that the present invention is not limited to the first to third embodiments.
For example, in the first to third embodiments, the rectangular irradiation area of the planar irradiation light emitted from the surface emitting backlight unit is divided into two equal parts in the longitudinal direction, but the luminance is not limited thereto. In the rectangular irradiation area, a partial irradiation area having a different luminance exists in a circular shape as shown in FIG. 8A, or a pattern that exists in a rectangular shape in the center as shown in FIG. 8B, Alternatively, it is also possible to arrange the brightness setting means so as to obtain irradiation light having various desired patterns such as a pattern including three or more partial irradiation areas instead of two partial irradiation areas. .

  Moreover, as a light source, not only linear light sources, such as a cold cathode tube, but point light sources, such as a light emitting diode, can also be used suitably.

  In addition, it is needless to say that the planar illumination device of the present invention can be effectively applied not only to the backlight of the liquid crystal display device but also to various other flat panel display backlights.

It is typical sectional drawing which shows the liquid crystal display module to which the surface emitting backlight unit as 1st Embodiment of this invention was applied. It is a perspective view which decomposes | disassembles and shows the structure of the surface emitting backlight unit part in the said liquid crystal display module. (A) is a top view which shows the structure of the light-guide plate rear surface of the said surface emitting backlight, (b) is the Z direction partial arrow directional view. (A) is a table | surface which shows the luminance measurement result of the display surface in the said liquid crystal display module, (b) is a top view which shows the measurement point, (c) is a table | surface which shows the luminance measurement result in a comparative example. (A), (b) is each explanatory drawing which shows the example of the inner surface treatment given to the groove | channel provided in the light-guide plate rear surface of the said light emission backlight unit, respectively. It is a perspective view which shows the main structures of the surface emitting backlight unit as 2nd Embodiment of this invention. It is a disassembled perspective view which shows the main structures of the surface emitting backlight unit as 3rd Embodiment of this invention. (A), (b) is each explanatory drawing which shows the other structural example of the irradiation area from which the brightness | luminance by the planar illuminating device of this invention differs, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage case 2 Cover case 3 Liquid crystal display panel 4, 5 Glass substrate 6 Sealing material 7 Liquid crystal 8, 9 Front and rear polarizing plate 10 Drive circuit element 11 Flexible wiring board 13 Backlight unit 14 Light guide plate 143 Groove 15 Cold cathode tube assembly 16 Light reflection sheet 17 Frame 18, 70 Optical sheet laminate 19 Light cover case 20 Electronic circuit board 51 Light reflection sheet (for groove)
52 Light Absorption Film 61 Black Dot 72 Deflection Prism Sheet 73 Brightness Enhancement Film Sheet

Claims (7)

A light guide plate that guides light incident from the end face and emits the light from the first main surface, and a light source that emits light toward the end face,
The light guide plate is
In the first region of the second main surface facing the first main surface, a plurality of luminance setting means are arranged so that the occupied area has a predetermined density,
In the second region of the second main surface, a plurality of light amounts from the light source emitted from the second region are larger than light amounts from the light source emitted from the first region. The brightness setting means is disposed at a higher density than the first region,
A planar illumination device, wherein a groove along the boundary portion is provided at a position corresponding to the boundary portion between the first region and the second region . The light guide plate has a pair of end faces facing each other so as to be parallel to each other,
The light source is arranged to irradiate light to each of the pair of end faces,
2. The planar illumination device according to claim 1, wherein the first region and the second region are arranged such that the boundary portion is a straight line parallel to the pair of end surfaces . Wherein the first region second region, the planar lighting device according to claim 1 or 2, characterized in that it is arranged light irradiation area so as to bisect. The planar illumination device according to any one of claims 1 to 3, wherein a light reflecting sheet or a light absorbing film is attached to the groove . The planar illumination device according to any one of claims 1 to 4, wherein the luminance setting means is a convex portion or a reflective film formed in a predetermined shape . A light guide plate that guides light incident from the end surface and emits the light from the first main surface toward the liquid crystal display panel, and a light source that emits light toward the end surface,
The light guide plate is
In the first region of the second main surface facing the first main surface, a plurality of luminance setting means are arranged so that the occupied area has a predetermined density,
In the second region of the second main surface, a plurality of light amounts from the light source emitted from the second region are larger than light amounts from the light source emitted from the first region. The brightness setting means is disposed at a higher density than the first region,
A liquid crystal display module, wherein a groove along the boundary portion is provided at a position corresponding to the boundary portion between the first region and the second region. A light guide plate that guides incident light and emits the light from the main surface, a prism sheet that aligns the optical path of the light emitted from the light guide plate in a predetermined direction, and two straight lines of light that has passed through the prism sheet An optical sheet that transmits one of the polarized light components and reflects the other, and a backlight unit,
A liquid crystal display panel disposed such that the prism sheet and the optical sheet are sequentially interposed between the light guide plate, and
With
The prism sheet and the optical sheet are arranged in other areas so as to avoid at least one of a plurality of areas set so that the luminance of light emitted from the backlight unit is different. A liquid crystal display module characterized by

Images