JP2008010321A - Light guide plate and back light unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate capable of sufficiently enhancing a brightness in a second region between first regions each of which is disposed to face a primary light source. <P>SOLUTION: A light guide plate 2 is used for a back light unit of a liquid crystal display. The light exit face 14 of the light guide plate 2 consists of a first region 26 disposed to face a primary light source, and a second region 28 between the first regions 26. In the first region 26, a plurality of first convexes 22 are formed at intervals in a predetermined direction and a direction substantially perpendicular to the predetermined direction. In the second region 28, a plurality of second convexes 24 are formed continuously in a predetermined direction and a direction substantially perpendicular to the predetermined direction. A convex of the first convexes 22 and the second convexes 24 is formed in such a shape as to have a square cone, a frustum of a square cone with a round top, a frustum of a right pyramid, or a frustum of a right pyramid with a round top. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light guide plate used for surface illumination of a liquid crystal display and the like and a backlight unit including the same.

  A liquid crystal display for displaying image information and the like is composed of a liquid crystal unit and a backlight unit for illuminating the liquid crystal unit, and the liquid crystal unit is disposed facing the surface side of the backlight, that is, the emission surface. Is done. The liquid crystal unit adjusts the amount of transmitted light by a liquid crystal cell, does not emit light itself, and the backlight unit is used as a light source for displaying image information and the like on the liquid crystal display.

  The backlight unit diffuses light emitted from the primary light source such as a cold cathode fluorescent lamp, a light guide plate for guiding light, a reflective plate that reflects light emitted from the primary light source toward the light guide plate, and the light guide plate. It is equipped with a diffusion sheet. One surface of the light guide plate functions as an incident surface, and a primary light source is disposed facing the incident surface. Also, the other surface facing the entrance surface of the light guide plate functions as an exit surface, and a diffusion sheet with shades is disposed opposite to the exit surface, and a liquid crystal unit is disposed opposite to the diffuse sheet with shades. Is done.

  In the backlight unit for illuminating the liquid crystal unit, it is required to illuminate the liquid crystal unit with high brightness from the back side and to uniformly illuminate the display area of the liquid crystal unit. It is required that the light introduced from the light source through the incident surface is efficiently emitted through the emission surface, and the light emitted from the emission surface is substantially uniform throughout the entire area.

  For this reason, a light guide plate having a concave pattern (or a convex pattern) on the exit surface has been proposed (see, for example, Patent Document 1). In this light guide plate, the concave pattern (or convex pattern) is composed of a large number of concave parts (or convex parts) having the same shape, and these concave parts (or convex parts) are formed in a regular quadrangular pyramid shape, for example.

  Further, as a processing apparatus for manufacturing a mold for such a light guide plate, there has been proposed an apparatus for processing a mold material by vibrating a quadrangular pyramid-shaped processing tool (for example, Patent Documents). 2). In this processing apparatus, a conical shape, a truncated cone shape, and a truncated pyramid shape are disclosed in addition to the quadrangular pyramid shape as the concave pattern (or convex pattern) of the light guide plate.

Utility Model Registration No. 3118155 JP 2005-67065 A

  However, in the light guide plate disclosed in Patent Document 1, the concave pattern (or the convex pattern) is provided almost uniformly at intervals in the vertical and horizontal directions (shown in FIG. 2). Therefore, in the region facing the primary light source (for example, the cold cathode fluorescent lamp), that is, the light source part above the primary light source, the light emitted from the primary light source is strong, and thus the light emitted from the light source part on the exit surface is strong. On the other hand, in the region not facing the primary light source, that is, in the non-light source portion between the adjacent first regions, the light emitted from the primary light source is weak, and thus the light emitted from the non-light source portion on the exit surface is dark, The brightness of the emitted light differs greatly between the light source part and the non-light source part of the light guide plate, and there is a problem that illumination unevenness occurs when the liquid crystal unit is illuminated. In order to solve such a problem, it has also been proposed to irregularly arrange the concave pattern (or a large number of concave parts (or convex parts) of the convex pattern 9). The design is difficult and the manufacturing is not easy.

  Patent Document 2 discloses a quadrangular pyramid shape, a conical shape, a truncated cone shape, and a quadrangular pyramid shape as the concave pattern (or convex pattern) of the light guide plate. However, these concave patterns (or convex pattern) are disclosed. ), The luminance can be increased more efficiently, and the illumination unevenness in the boundary region between the light source part and the non-light source part of the light guide plate can be suppressed. There is no disclosure about what can be done.

The objective of this invention is providing the light-guide plate which can fully raise the brightness | luminance in the 2nd area | region which exists between the 1st area | regions corresponding to a primary light source.
Another object of the present invention is to provide a light guide plate that can suppress a sudden change in luminance in the boundary region between the first region and the second region and obtain substantially uniform luminance over the entire exit surface. It is.

  Still another object of the present invention is to provide a backlight unit that can uniformly irradiate a liquid crystal unit with sufficient luminance.

  A light guide plate according to a first aspect of the present invention is a light guide plate used in a backlight unit of a liquid crystal display, and light from a plurality of primary light sources arranged at intervals in a predetermined direction is incident thereon. An incident surface; and an exit surface that faces the entrance surface and emits light introduced from the entrance surface. The entrance surface or the exit surface corresponds to the plurality of primary light sources. A plurality of first regions, and a second region located between the plurality of first regions, wherein the plurality of first regions include any of a plurality of first concave portions and convex portions. A plurality of second recesses and projections are provided in the plurality of second regions in the predetermined direction and the predetermined direction. It is characterized in that a plurality are provided continuously in a direction perpendicular to To.

  In the light guide plate according to claim 2 of the present invention, the plurality of first recesses are provided in the first region at intervals in the predetermined direction and a direction perpendicular to the predetermined direction. In the second region, the plurality of second convex portions are provided continuously in the predetermined direction and in a direction perpendicular to the predetermined direction.

  The light guide plate according to claim 3 of the present invention is a light guide plate used in a backlight unit of a liquid crystal display, and receives light from a plurality of primary light sources arranged at intervals in a predetermined direction. An incident surface that is incident and a surface that faces the incident surface and emits light that is introduced from the incident surface. The incident surface or the emitting surface includes a plurality of primary light sources. A plurality of corresponding first regions, and a second region located between the plurality of first regions, wherein the plurality of first recesses or protrusions are in the predetermined direction and the plurality of first regions. The plurality of second regions are provided with a V-shaped peak and valley in a direction substantially perpendicular to the predetermined direction, and substantially in the predetermined direction or the predetermined direction. It is characterized by being provided alternately and continuously in an upward vertical direction.

  In the light guide plate according to claim 4 of the present invention, the plurality of first concave portions or convex portions are spaced apart in the predetermined direction by 300 to 600 μm in the first region, and the predetermined direction. It is characterized by being provided with an interval of 300 to 600 μm in a direction perpendicular to the above.

  In the light guide plate according to claim 5 of the present invention, the plurality of first and second recesses or recesses are a regular quadrangular pyramid, a regular quadrangular pyramid having a rounded tip, a regular quadrangular pyramid, or a tip corner. It has a round regular quadrangular pyramid shape, and one side of the plurality of first and second concave portions or convex portions is 80 to 150 μm.

  In the light guide plate according to claim 6 of the present invention, a plurality of light source receiving recesses are provided on the incident surface corresponding to the plurality of primary light sources, and the plurality of primary light sources are provided in the plurality of light source receiving recesses. Each of the light sources is housed, the first and second regions are disposed on the emission surface, the first region is provided corresponding to the plurality of light source housing recesses, and the second region is the plurality of light source housings. It is provided correspondingly between the recesses.

  In the light guide plate according to claim 7 of the present invention, a gradation region for blurring light emitted from the boundary region is provided in a boundary region between the first region and the second region, and the gradation The region is provided with a plurality of diffusion grooves or ridges extending linearly from the second region to the first region.

  In the light guide plate according to an eighth aspect of the present invention, a gradation region for blurring emitted light from the boundary region is provided in a boundary region between the first region and the second region, and the gradation The region is provided with a diffusion peak and a diffusion valley extending from the second region to the first region.

  Furthermore, a backlight unit according to a ninth aspect of the present invention includes a light guide plate according to any one of the first to eighth aspects, and a plurality of primary light sources disposed to face an incident surface of the light guide plate. And a light diffusing sheet with shading disposed to face the light exit surface of the light guide plate.

  Furthermore, in the backlight unit according to claim 10 of the present invention, the irradiation light from the plurality of primary light sources is reflected toward the incident surface on the side opposite to the light guide plate of the plurality of primary light sources. And a plurality of receiving recesses for receiving the plurality of primary light sources are defined in the reflecting plate.

  According to the light guide plate of the first aspect of the present invention, the plurality of first concave portions (or convex portions) are provided in the predetermined direction and the predetermined direction in the plurality of first regions of the emission surface (or the incident surface). In the second region, a plurality of second concave portions (or convex portions) are continuously provided in a predetermined direction and a direction perpendicular to the predetermined direction. . In this second region, there is little light from the primary light source, but since there are many second concave portions (or convex portions), the light from the primary light source is sufficiently diffused by these concave portions (or convex portions) and the luminance is increased. Enhanced. In addition, the first region has a large amount of light from the primary light source, but the presence of the first concave portion (or convex portion) is small. Therefore, the diffusion of light from the primary light source is less than that of the second region and the luminance is low. Rise is suppressed. Thus, while the brightness in the second area is sufficiently increased, an increase in brightness is suppressed in the first area, and uneven brightness in the first area and the second area can be reduced while increasing the brightness in the second area. In addition, although the 1st recessed part (or convex part) of a 1st area | region and the 2nd recessed part (or convex part) of a 2nd area | region may be the same shape, a different shape may be sufficient.

  Further, according to the light guide plate according to claim 2 of the present invention, the light guide plate is formed by, for example, injection molding, and such an injection molding die is in the first region while vibrating the processing tool. In the second region, the first region is provided with a first recess, and the second region is formed by pressing, and the second region is formed by cutting. In, a 2nd convex part is provided.

  According to the light guide plate of the present invention, the first concave portion (or the convex portion) has a predetermined direction and a predetermined direction in the plurality of first regions of the emission surface (or the incident surface). In the second region, V-shaped peaks and valleys are continuously provided in a predetermined direction (or in a direction substantially perpendicular to the predetermined direction). Provided. In this second region, there is little light from the primary light source, but since the peaks and valleys are continuously present, the light from the primary light source is sufficiently diffused by these peaks and valleys to increase the brightness. . In addition, the first region has a large amount of light from the primary light source, but the presence of the first concave portion (or convex portion) is small. Therefore, the diffusion of light from the primary light source is less than that of the second region and the luminance is low. Rise is suppressed. Thus, while the brightness in the second area is sufficiently increased, an increase in brightness is suppressed in the first area, and uneven brightness in the first area and the second area can be reduced while increasing the brightness in the second area.

  According to the light guide plate according to claim 4 of the present invention, the first region has a plurality of first concave portions or convex portions spaced at intervals of 300 to 600 μm in a predetermined direction and with respect to the predetermined direction. Since it is provided at an interval of 300 to 600 μm in the vertical direction, the luminance of the first region can be increased while taking the luminance of the second region into consideration.

  According to the light guide plate of claim 5 of the present invention, the first and second recesses (or projections) are a regular quadrangular pyramid, a regular quadrangular pyramid having a rounded tip, a regular quadrangular pyramid, or a tip angle. Since the portion has a round regular quadrangular pyramid shape, the light from the primary light source can be sufficiently diffused to increase the luminance. In particular, when the tip is a rounded quadrangular pyramid shape, a regular quadrangular pyramid shape, and a tip corner is a rounded regular pyramid shape, the light reflection surface is increased, and the light from the primary light source is diffused more efficiently. Brightness can be increased.

  According to the light guide plate of claim 6 of the present invention, the light incident surface is provided with the light source accommodating recess, and each primary light source is accommodated in the corresponding light source accommodating recess, so that the light from the primary light source is received. It is efficiently guided to the incident surface of the light guide plate, and the brightness of the light guide plate can be increased. In addition, since the first area is provided corresponding to the light source accommodation recess and the second area is provided corresponding to between the adjacent light source accommodation recesses, the irradiation light from the primary light source is in the second area. The luminance is sufficiently increased, and the increase in luminance is suppressed in consideration of the luminance of the second region in the first region where the irradiation light from the primary light source is strong.

  According to the light guide plate of claim 7 of the present invention, the gradation region existing in the boundary region between the first region and the second region includes a plurality of linearly extending from the second region to the first region. Since the diffusion grooves or the diffusion ridges are provided, it is possible to eliminate a sudden luminance difference by blurring the light emitted from the boundary region with a relatively simple configuration.

  According to the light guide plate of claim 8 of the present invention, the gradation region existing in the boundary region between the first region and the second region has a diffusion peak portion and a diffusion extending from the second region to the first region. Since a trough is provided, even if configured in this way, it is possible to eliminate a sudden luminance difference by blurring the outgoing light from the boundary region.

  Furthermore, according to the backlight unit described in claim 9 of the present invention, the light guide plate according to any one of claims 1 to 8 is provided, and a light diffusing sheet with light and shade is provided so as to face the exit surface of the light guide plate. Therefore, the emitted light guided to the liquid crystal unit from the light guide plate through the light diffusion sheet with shading can be made uniform.

  Furthermore, according to the backlight unit according to claim 10 of the present invention, the reflecting plate is disposed on the side opposite to the light guide plate of the next light source, and the reflecting plate has a receiving recess for receiving the primary light source. Therefore, the light from the primary light source can be efficiently reflected and guided to the light guide plate.

  Hereinafter, embodiments of a light guide plate according to the present invention and a backlight unit including the same will be described with reference to the accompanying drawings. 1 is a sectional view showing a part of a backlight unit according to the present invention, and FIG. 2 is a partially enlarged front view showing a part of a light guide plate in the backlight unit of FIG. These are the expanded sectional views by the III-III line in FIG.

  1 and 2, the illustrated backlight unit 2 includes a light guide plate 4 for guiding light, a cold cathode fluorescent lamp 6 as a primary light source, and an illumination light from the cold cathode fluorescent lamp 6. A reflection plate 8 and a light diffusion sheet 10 with light and shade for diffusing light are provided. The light guide plate 4 is formed in a rectangular plate shape, and the lower surface 12 in FIG. 1 functions as an incident surface on which illumination light from the cold cathode fluorescent lamp 6 is incident, and the upper surface 14 in FIG. 1 is a liquid crystal unit (not shown). It functions as an emission surface that emits light toward.

  The cold cathode fluorescent lamp 6 is disposed so as to face the incident surface 12 (lower surface) of the light guide plate 4. In this embodiment, the incident surface 12 of the light guide plate 4 is provided with a plurality of (two shown in FIG. 1) light source housing recesses 16 at intervals in a predetermined direction (left and right directions in FIGS. 1 and 2). The cold cathode fluorescent lamp 6 is housed in the light source housing recess 16. Each light source accommodating recess 16 extends in a direction perpendicular to the predetermined direction (a direction perpendicular to the paper surface in FIG. 1 and a vertical direction in FIG. 2). Accordingly, each cold cathode fluorescent lamp 6 is also a direction perpendicular to the predetermined direction. It is arrange | positioned at the light source accommodation recessed part 16 so that it may extend.

  Each light source accommodation recessed part 16 is arrange | positioned at intervals of about 30-45 mm, for example, 35 mm, The width W1 is formed in about 8-15 mm, for example, 10 mm, The width direction both ends are formed in an arc shape, The width direction The central part is formed flat. The cold cathode fluorescent lamp 6 is disposed at the center in the width direction of the light receiving recess 16.

  The reflection plate 8 is disposed on the opposite side of the light guide plate 4 so as to face the plurality of cold cathode fluorescent lamps 6, and is attached to the incident surface 12 of the light guide plate 4. The reflecting plate 8 is formed of, for example, a white resin such as polycarbonate resin or ABS resin, and a portion 18 corresponding to the light source housing recess 16 of the light guide plate 4 is curved outwardly, and the inner surface of the curved portion 18 is Each cold cathode fluorescent lamp 6 is housed in a housing space 22 that defines the housing recess 20 and is defined by the housing recess 20 of the reflecting plate 8 and the light source housing recess 16 of the light guide plate 4. For example, the housing recess 20 has the same shape as the light source housing recess 16 of the incident surface 12. With this configuration, the irradiation light directed from the cold cathode fluorescent lamp 6 toward the light guide plate 4 is directly incident from the light source housing recess 14 of the incident surface 12 and from the cold cathode fluorescent lamp 6 toward the reflecting plate 4. The irradiation light is reflected from the inner surface of the housing recess 20 of the reflector 4 and then enters from the light source housing recess 14 of the incident surface 12.

  In this embodiment, convex portions 22 and 24 having a predetermined shape are provided on the exit surface 14 of the light guide plate 4. In the first region 26 of the emission surface 14 corresponding to each cold cathode fluorescent lamp 6 (in this embodiment, the region above the cold cathode fluorescent lamp 6 and above the light source housing recess 16), the cold cathode fluorescent lamp is used. The irradiation light from 6 is strong, and therefore, in the first region 26, a plurality of first convex portions 22 are provided at intervals. In this embodiment, the first protrusions 22 are provided at a predetermined interval of about 300 to 600 μm in a predetermined direction (left and right direction in FIGS. 1 and 2), for example, an interval of 400 μm, and with respect to the predetermined direction. Are provided at predetermined intervals of about 300 to 600 μm, for example, 400 μm, in a substantially vertical direction (a direction perpendicular to the paper surface in FIG. 1 and a vertical direction in FIG. 2).

  Further, in the second region 28 located between the adjacent first regions 26 (in this embodiment, the upper region where the cold cathode fluorescent lamp 6 does not exist and the region above the portion that is out of the light source housing recess 16), Irradiation light from the cold cathode fluorescent lamp 6 is weak, and therefore a plurality of second convex portions 24 are continuously provided in the second region 28. That is, the second convex portion 24 is provided continuously in a predetermined direction and is provided continuously in a direction substantially perpendicular to the predetermined direction.

  In this embodiment, the 1st convex part 22 of the 1st field 26 and the 2nd convex part 24 of the 2nd field 28 are substantially the same shape, and the tip part is formed in the shape of a regular square pyramid. Referring also to FIG. 3, the size L (see FIG. 2) of one side of the bottom of the first and second convex portions 22 and 24 is 80 to 150 μm, preferably 100 to 140 μm, for example, 120 μm, Moreover, the height H1 (refer FIG. 3) is 30-70 micrometers, Preferably it is 40-60 micrometers, for example, it forms in 50 micrometers, and these convex parts 22 and 24 are the distance H2 from the vertex part P in the height direction. That is, the part from the apex P to 6 to 35 μm is formed in a circular arc shape. The distance H2 from the apex P formed in the cross-sectional arc shape is large when the height H1 of the convex pyramids 22 and 24 is high, and this distance H2 is 20 to 50% of the height H, preferably The size is set to a ratio of 20 to 35%. By making the first and second convex portions 22 and 24 for diffusing light into such a regular quadrangular pyramid shape, it is possible to increase the diffusion efficiency and increase the brightness, and from the apex portion P to a predetermined range. By forming the portion in an arc shape, it is possible to increase the diffusion surface and increase the diffusion efficiency, suppress the collection of light on the apex portion P, and make the brightness of the emission surface 4 more uniform.

  In this embodiment, the first region 26 is provided corresponding to the width W1 of the light source housing recess 16 of the light guide plate 4. The first region 26 is guided from the cold cathode fluorescent lamp 6 through the light guide plate 4. In consideration of the brightness of the light, the first region 26 may be set up to a portion that is somewhat wider than the width W1 of the light source housing recess 16, and the width of the first region 26 is 8 to 24 mm. For example, it can be set to about 20 mm.

  The light diffusing sheet 10 with light and shade is disposed to face the light exit surface 14 (upper surface) of the light guide plate 4. The light diffusing sheet 10 is formed of polycarbonate resin, PET resin, or the like, and has a microdot pattern on the surface thereof, and light emitted from the light emitting surface 14 of the light guide plate 4 through the light diffusing sheet 10 with light and shade is substantially present in the entire area. It is formed so as to be uniform. That is, in the region corresponding to the first region 26 of the exit surface 14 of the light guide plate 4, the number of microdots per unit area increases, and in the region corresponding to the second region 28 of the exit surface 14, the unit. The number of micro dots per area is reduced, and in the boundary region between the first region 26 and the second region 28, the number of micro dots per unit area gradually decreases from the first region 26 toward the second region 28. Formed to do. Such a microdot pattern is formed by screen printing on the surface of the light diffusing sheet using ink containing a light diffusing agent, or by applying a texture to the surface of the light diffusing sheet.

    A protective sheet 32 is further provided on the surface of the light-diffusing sheet 10 with light and shade so as to cover the entire area. The protective sheet 32 is formed of a thin transparent resin sheet, and protects the light diffusion sheet 10 with shading. A liquid crystal unit (not shown) is disposed to face the light diffusion sheet 10 with light and shade, and light from the light diffusion sheet 10 is projected from the back side of the liquid crystal unit.

  Referring mainly to FIG. 3, in the backlight unit 2 described above, the irradiation light from each cold cathode fluorescent lamp 6 is directly or downwardly irradiated in the upward direction in FIG. In the case of light, after being reflected by the reflecting plate 8, it is introduced into the light guide plate 4 from the incident surface 12, and the introduced irradiation light is emitted from the emitting surface 14. At this time, since the plurality of convex portions 22 are provided at intervals in the first region 26 of the emission surface 14, the diffusion of light is small and the increase in luminance is small. In this case, since the plurality of convex portions 24 are continuously provided, the light is sufficiently diffused and the luminance is greatly increased, and the light emitted from the light exit surface 14 can be made uniform.

  The light emitted from the emission surface 14 of the light guide plate 4 is emitted through the light diffusion sheet 10 with shades and the protective sheet 32, and this emitted light is projected from the back side to a liquid crystal unit (not shown). The liquid crystal unit is projected. At this time, since the microdot pattern is formed on the light diffusion sheet 10 with light and shade, the emitted light is made more uniform by this microdot pattern, and thus the liquid crystal unit can be irradiated more uniformly. Such a liquid crystal unit is a liquid crystal unit for a liquid crystal television, a car navigation system, a monitor, or the like.

  In the above-described embodiment, since the light source accommodating recess 16 is provided on the incident surface 12 of the light guide plate 4, the light diffusion convex portions 22 and 24 are provided on the exit surface 14. When the concave portion 16 is omitted, the first and second convex portions 22 and 24 may be provided on the incident surface 12.

  In the above-described embodiment, the light diffusing first and second convex portions 22 and 24 are provided on the light exit surface 14 of the light guide plate 4, but instead of the first and second convex portions 22 and 24, It can be configured as shown in FIG. FIG. 4 is an enlarged cross-sectional view of a part of the second embodiment of the light guide plate. In the following embodiments, substantially the same members as those of the embodiments shown in FIGS. A reference number is assigned and description thereof is omitted.

  In FIG. 4, in this embodiment, in the first region (region above the cold cathode fluorescent lamp) of the emission surface 14 corresponding to the cold cathode fluorescent lamp (not shown), the irradiation light from the cold cathode fluorescent lamp is irradiated. Due to its strength, the plurality of first concave portions 42 are spaced apart in a predetermined direction and a direction perpendicular to the predetermined direction, for example, in the same manner as in the above-described embodiment, an interval of about 300 to 600 μm in the predetermined direction with respect to the predetermined direction In the second region (the upper region where there is no cold cathode fluorescent lamp) which is provided at intervals of about 300 to 600 μm in the substantially vertical direction and is located between the adjacent first regions, cold cathode fluorescent light is used. Since the irradiation light from the lamp is weak, the plurality of second recesses 44 are continuously provided in a predetermined direction and a direction perpendicular to the predetermined direction, as in the above-described embodiment.

  The first and second recesses 42 and 44 are formed in substantially the same shape, and the size of one side of the first recess 42 (second recess 44) is 80 to 150 μm, preferably 100 to 140 μm. Moreover, the depth h1 (refer FIG. 4) is 30-70 micrometers, Preferably it forms in 40-60 micrometers. The first concave portion 42 (second concave portion 44) is formed in a circular arc shape at a portion from the bottom point p to a distance h2 in the depth direction, that is, from 6 to 35 μm from the bottom point p. . The distance h2 from the bottom point portion p formed in a circular arc shape increases when the depth h1 of the first concave portion 42 (second concave portion 44) having a regular quadrangular pyramid is deep, and this distance h2 is 20 of the depth h2. It is set to a size of ˜50%, preferably 20-35%. By making the first and second recesses 42 and 44 for diffusing light into such a regular quadrangular pyramid shape, the diffusion efficiency can be increased and the luminance can be increased as described above. Moreover, you may make it provide such 1st and 2nd recessed parts 42 and 44 in the incident surface instead of the output surface 14 of 4 A of light-guide plates.

  The plurality of first and second protrusions provided on the light exit surface of the light guide plate may be configured as shown in FIG. Fig.5 (a) is a partial expansion front view which expands and shows a part of 3rd Embodiment of a light-guide plate, FIG.5 (b) is the partial expansion by the BB line in Fig.5 (a). It is sectional drawing.

  5, in this embodiment, first and second convex portions 52 and 54 are provided on the exit surface 14 of the light guide plate 4B, and in the same manner as in the above-described embodiment, the first region has a predetermined direction and a predetermined direction. The first convex portion 52 is provided at an interval, and the second convex portion 54 is continuously provided in the second region in a predetermined direction and a direction perpendicular to the predetermined direction.

  The first and second convex portions 52 and 54 have substantially the same shape and are formed in a regular quadrangular pyramid shape. These 1st convex parts 52 (2nd convex part 54) are the same shapes as what removed the roundness of the front-end | tip part in the 1st convex part 22 (2nd convex part 24) of embodiment of FIGS. 1-3. Well, the size L3 of one side of the bottom of the convex portion 52 (54) is 80 to 150 μm, preferably 100 to 140 μm, and the height H3 is 30 to 70 μm, preferably 40 to 60 μm, for example 50 μm. Formed. Even if such first and second convex portions 52 and 54 are provided, the same effect as described above is achieved.

  The light diffusion recess provided on the light exit surface of the light guide plate may be configured as shown in FIG. 6 instead of the first recess 42 (second recess 44) shown in FIG. FIG. 6 is an enlarged partial cross-sectional view showing a part of the fourth embodiment of the light guide plate.

  In FIG. 6, in this embodiment, first and second recesses 62 and 64 are provided on the light exit surface 14 of the light guide plate 4 </ b> C, and the first region is spaced in a predetermined direction and a predetermined direction as in the above-described embodiment. A first recess 62 is provided, and a second recess 64 is provided continuously in the second region in a predetermined direction and a direction perpendicular to the predetermined direction.

  The first and second recesses 62 and 64 have substantially the same shape and are formed in a regular quadrangular pyramid shape. These first concave portions 62 (second concave portions 64) may have the same shape as that of the first concave portion 42 (second concave portion 44) of the embodiment of FIG. The size of one side of the bottom of the second recess 64) is 80 to 150 μm, preferably 100 to 140 μm, and the depth h4 is 30 to 70 μm, preferably 40 to 60 μm. Even if such first and second recesses 62 and 64 are provided, the same effect as described above can be achieved.

  A plurality of first and second convex portions provided on the light exit surface of the light guide plate may be configured as shown in FIG. FIG. 7 is an enlarged partial cross-sectional view showing a part of the fifth embodiment of the light guide plate.

  In FIG. 7, in this embodiment, first and second convex portions 72 and 74 are provided on the exit surface 14 of the light guide plate 4D, and in the same manner as in the above-described embodiment, the first region has a predetermined direction and a predetermined direction. The 1st convex part 72 is provided at intervals, and the 2nd convex part 74 is provided in the 2nd area | region in the direction perpendicular | vertical with respect to the predetermined direction and the predetermined direction.

  The first and second convex portions 72 and 74 have substantially the same shape and are formed in a regular quadrangular pyramid shape. These 1st convex parts 72 (2nd convex part 74) are the same shapes as what remove | eliminated by cutting horizontally the front-end | tip part in the 1st convex part 52 (2nd convex part 54) of embodiment of FIG. It's okay. The size of the base of the first convex portion 72 (second convex portion 74) may be the same as that of the embodiment of FIG. 5, and its height H6 is the height H5 of the regular quadrangular pyramid (the regular quadrangular pyramid shape of FIG. 5). 10 to 40% of the height H7 may be cut. When the first and second convex portions 72 and 74 having such a regular quadrangular pyramid shape are provided, the number of reflecting surfaces is increased, thereby increasing the diffusion efficiency and increasing the luminance. The concentration of light on the top of the regular quadrangular pyramid can be suppressed.

  A plurality of first and second convex portions provided on the light exit surface of the light guide plate may be configured as shown in FIG. FIG. 8 is a partially enlarged cross-sectional view showing a part of the sixth embodiment of the light guide plate in an enlarged manner. In FIG. 8, in this embodiment, first and second convex portions 82 and 84 are provided on the emission surface 14 of the light guide plate 4E, and in the same manner as in the above-described embodiment, the first region has a predetermined direction and a predetermined direction. A first convex portion 82 is provided at an interval, and a second convex portion 84 is provided in the second region continuously in a predetermined direction and a direction perpendicular to the predetermined direction. These first and second convex portions 82 and 84 have substantially the same shape, and the tip corner portion in the regular quadrangular pyramid shape shown in FIG. 7 is rounded, and the radius r of this corner portion is formed to be about 1 to 6 μm. The By providing such first and second convex portions 82 and 84, the same effect as described above can be achieved, and in addition, by forming a square tip of the regular quadrangular pyramid in a round shape, light at the tip corner can be obtained. Can be prevented.

  In the embodiment of FIG. 7 (or FIG. 8), first and second convex portions 72 having a regular quadrangular frustum shape (or a regular quadrangular frustum shape having a rounded tip corner) on the light exit surface 14 of the light guide plate 4D (or 4E), 74 (or 82, 84) is provided, but instead of such a convex portion, as shown in FIGS. 4 and 6, a regular quadrangular frustum shape (or a rounded tip corner portion) is formed on the exit surface 14 thereof. Shape) first and second recesses may be provided.

In the embodiment shown in FIGS. 3 to 8, the first and second convex portions or concave portions for light diffusion are provided on the exit surface of the light guide plate. However, these may be provided on the entrance surface. .
In the above-described embodiment, the first and second convex portions (or concave portions) provided in the first and second regions of the light guide plate are formed in substantially the same shape, but it is not always necessary to have the same shape. The first region of the light guide plate is provided with, for example, the first convex portion, that is, one of the first convex portions described above (or any one of the first concave portions described above), and the second region is provided with, for example, the second concave portion, that is, Any of the above-described second concave portions (or any of the above-described second convex portions) may be provided.

  In the various light guide plates described above, when a luminance difference occurs in the boundary region between the first region 26 and the second region 28 on the emission surface 14, it can be configured as shown in FIG. 9. FIG. 9 is a partially enlarged sectional view showing a part of the seventh embodiment of the light guide plate in an enlarged manner.

  In FIG. 9, in the light guide plate 4 </ b> F of this embodiment, a gradation region 102 is provided in the boundary region between the first region 26 and the second region 28. The gradation region 102 is provided with a diffusion groove 104 extending linearly from the second region 28 toward the first region 26. The diffusion groove 104 has a predetermined direction (that is, a cold cathode fluorescent lamp (not shown)). For example, it is provided corresponding to the interval of the first protrusions 22 provided in the first region 26 with an interval in a direction perpendicular to the interval). The diffusion groove 104 has a V-shaped cross section, for example, and extends linearly from the V-shaped portion between the corresponding pair of second protrusions 24 of the second region 28 toward the first region 26. A length of about 5 to 2.0 mm is formed. Other configurations of the light guide plate 4F are substantially the same as those of the light guide plate 4 of the embodiment shown in FIGS.

  In the light guide plate 4F, since the diffusion groove 104 is provided in the gradation region 102, light is diffused by the diffusion groove 104, and the brightness of the boundary region between the first region 26 and the second region 28 is rapidly changed. And the change in brightness of the boundary region is blurred, and thus, in combination with a light diffusion sheet with shading (not shown), the emitted light emitted toward the liquid crystal unit is made more uniform. can do.

  The interval at which the diffusion groove 104 is provided can be set as appropriate, and may be provided corresponding to each of the V-shaped portions between the pair of second protrusions 24 in the second region 28. The diffusion groove 104 may be provided at an appropriate interval regardless of the V-shaped portion between the two convex portions 24.

  In the above-described embodiment, the diffusion groove 104 is provided. However, the present invention is not limited to such a configuration, and a mountain-shaped diffusion protrusion may be provided. The effect is achieved.

  In the above-described embodiments, in each of the second regions of the light guide plate, the second convex portion or the concave portion is continuously provided in the predetermined direction and the direction perpendicular to the predetermined direction. Thus, it can be configured as shown in FIG.

  In FIG. 10, in the light guide plate 4 </ b> G, a V-shaped peak portion 112 and a valley portion 114 are provided in the second region 28 of the emission surface 14. These peak portions 112 and valley portions 114 extend linearly in a predetermined direction (left and right direction in FIG. 10), and are provided alternately and continuously in a direction substantially perpendicular to the predetermined direction. The width W3 of the peak portion 112 (that is, the width in the direction perpendicular to the predetermined direction) is, for example, a first convex portion 116 (in this form, a regular quadrangular pyramid shape) provided in the first region 26 of the emission surface 14. It is formed so as to be equal to the size of one side of the bottom, and is formed to about 80 to 150 μm, for example, 120 μm, and its height is formed to about 40 to 80 μm, for example, 60 μm. A cold cathode fluorescent lamp (not shown) as a primary light source is disposed at intervals in the predetermined direction and extends in a direction perpendicular to the predetermined direction (that is, orthogonal to the peak portion 112 and the valley portion 114). To be arranged). The other configuration of the light guide plate 4G is substantially the same as that of the light guide plate 4 shown in FIGS. 1 to 3 using the first convex portion 22 shown in FIG.

  In the light guide plate 4G, in the first region 26 of the emission surface 14 corresponding to a cold cathode fluorescent lamp (not shown), the plurality of first protrusions 116 are in a predetermined direction and a direction substantially perpendicular to the predetermined direction. Since they are provided at intervals, the diffusion of the irradiation light from the cold cathode fluorescent lamp is small and the increase in luminance is suppressed. On the other hand, in the second region 28 of the emission surface 14, the peaks 112 and valleys 114 are formed. Since they are provided continuously, the irradiation light is sufficiently diffused and the luminance is sufficiently enhanced. Therefore, even in the case of such a configuration, the light emitted from the light exit surface 14 of the light guide plate 4G can be made uniform as in the above-described embodiment.

  In this embodiment, the peak portion 112 and the valley portion 114 are continuously provided in a direction perpendicular to the predetermined direction. However, the present invention is not limited to such a configuration, and the peak portion 112 and the valley portion 114 are arranged in the predetermined direction. You may make it provide so that it may arrange | position continuously (in other words, the peak part 112 and the trough part 114 extend substantially in parallel with a cold cathode fluorescent lamp).

  Moreover, you may make it provide the diffusion groove | channel (or diffusion protrusion) on the light-guide plate 4G of such embodiment similarly to embodiment shown in FIG. That is, a gradation region is provided in the boundary region between the first region 26 and the second region 28 on the emission surface 14, and a diffusion groove (or diffusion protrusion) that extends linearly from the second region 28 to the first region 26 in the gradation region. For example, in the case of a diffusion groove, it extends linearly from the trough 114 (the whole trough 114 or the trough 114 having a predetermined interval) of the second region 28 toward the first region 26. Can be formed. Further, in this gradation area, in relation to a part of the peak part 112 and the valley part 114 of the second area 28, a diffusion peak extending linearly from the end part of the peak part 112 and the valley part 114 to the first area 26. A part and a diffusion valley part may be provided. In this way, by providing diffusion grooves (or diffusion protrusions) or diffusion peaks and diffusion valleys in the gradation area, light is diffused in the gradation area as described above, and the first area 26 and A sudden change in the luminance of the boundary region of the second region 28 can be suppressed.

  The various light guide plates 4 (4A to 4G) described above can be manufactured, for example, by an injection molding method, a hot press transfer method, or the like, and a mold used for the injection molding method or the like is a pressing method using vibration ( The manufacturing method disclosed in JP-A-2005-67065), a cutting method, and the like can be used.

  As mentioned above, although various embodiment of the light-guide plate according to this invention and a backlight unit using the same was described, this invention is not limited to this embodiment, A various deformation | transformation is carried out, without deviating from the scope of the present invention. Or it can be modified.

Sectional drawing which shows a part of backlight unit according to this invention. The partial enlarged front view which expands and shows a part of light-guide plate in the backlight unit of FIG. The expanded sectional view by the III-III line in FIG. Sectional drawing which expands and shows a part of 2nd Embodiment of a light-guide plate. FIG. 5A is a partially enlarged front view showing a part of the third embodiment of the light guide plate in an enlarged manner, and FIG. 5B is a partially enlarged sectional view taken along the line BB in FIG. 5A. The partial expanded sectional view which expands and shows a part of 4th Embodiment of a light-guide plate. The partial expanded sectional view which expands and shows a part of 5th Embodiment of a light-guide plate. The partial expanded sectional view which expands and shows a part of 6th Embodiment of a light-guide plate. The partial expanded sectional view which expands and shows a part of 7th Embodiment of a light-guide plate. The partial expanded sectional view which expands and shows a part of 8th Embodiment of a light-guide plate.

Explanation of symbols

2 Backlight unit 4, 4A, 4B, 4C, 4D, 4E, 4F, 4G Light guide plate 6 Cold cathode fluorescent lamp 8 Reflector plate 10 Light diffusion sheet with light and shade 12 Incident surface 14 Emission surface 16 Light source accommodating recess 22, 24, 52 , 54, 72, 74, 82, 84, 116 Convex portion 26 First region 28 Second region 42, 44, 62, 64 Concave portion 112 Mountain portion 114 Valley portion

Claims (10)

  A light guide plate used in a backlight unit of a liquid crystal display, which includes an incident surface on which light from a plurality of primary light sources arranged at intervals in a predetermined direction is incident, and a surface facing the incident surface. And a plurality of first regions corresponding to the plurality of primary light sources, and the plurality of first regions on the incident surface or the emission surface. A second region located between the first region and the plurality of first regions, wherein any of the plurality of first concave portions and convex portions is substantially perpendicular to the predetermined direction and the predetermined direction. The plurality of second regions are provided with a plurality of second recesses and projections continuously in the predetermined direction and in a direction perpendicular to the predetermined direction. A light guide plate characterized by comprising:   In the first region, the plurality of first concave portions are provided at intervals in the predetermined direction and in a direction perpendicular to the predetermined direction, and in the second region, the plurality of second convex portions are provided. The light guide plate according to claim 1, wherein the light guide plate is provided continuously in a direction perpendicular to the predetermined direction and the predetermined direction.   A light guide plate used in a backlight unit of a liquid crystal display, which includes an incident surface on which light from a plurality of primary light sources arranged at intervals in a predetermined direction is incident, and a surface facing the incident surface. And a plurality of first regions corresponding to the plurality of primary light sources, and the plurality of first regions on the incident surface or the emission surface. A plurality of first recesses or projections spaced apart in the predetermined direction and in a direction substantially perpendicular to the predetermined direction. In addition, V-shaped peaks and valleys are alternately and continuously provided in the predetermined direction or in a direction substantially perpendicular to the predetermined direction in the plurality of second regions. A light guide plate characterized by   In the first region, the plurality of first concave portions or convex portions are spaced apart by 300 to 600 μm in the predetermined direction, and spaced by 300 to 600 μm in a direction perpendicular to the predetermined direction. The light guide plate according to claim 1, wherein the light guide plate is provided.   The plurality of first and second recesses or recesses have a regular quadrangular pyramid shape, a regular quadrangular pyramid shape with a rounded tip portion, a regular quadrangular pyramid shape, or a regular quadrangular pyramid shape with a rounded tip corner portion. 5. The light guide plate according to claim 1, wherein one side of the bottom of the two concave portions or the convex portions is 80 to 150 μm.   The incident surface is provided with a plurality of light source accommodating recesses corresponding to the plurality of primary light sources, the plurality of primary light sources are respectively accommodated in the plurality of light source accommodating recesses, and the first and second regions are The first region is provided corresponding to the plurality of light source receiving recesses, and the second region is provided corresponding to the plurality of light source receiving recesses. The light guide plate according to claim 1.   The boundary area between the first area and the second area is provided with a gradation area for blurring the light emitted from the boundary area, and the gradation area is linear from the second area to the first area. The light guide plate according to claim 1, wherein a plurality of diffusion grooves or diffusion protrusions are provided.   A gradation area for blurring light emitted from the boundary area is provided in a boundary area between the first area and the second area, and the gradation area extends from the second area to the first area. The light guide plate according to claim 3, wherein a diffusion peak portion and a diffusion valley portion are provided.   The light guide plate according to any one of claims 1 to 8, a plurality of primary light sources disposed to face an incident surface of the light guide plate, and a shade disposed to face an output surface of the light guide plate. And a light diffusing sheet.   On the opposite side of the plurality of primary light sources from the light guide plate, a reflector for reflecting the irradiation light from the plurality of primary light sources toward the incident surface is disposed, and the reflector includes the plurality of primary light sources. The backlight unit according to claim 9, wherein a plurality of housing recesses for housing the primary light source are defined.

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