JP2006189796A - Light guide plate and back light module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate to emit the light in a direction perpendicular to the emitting surface and a back light module using this light guide plate without arranging optical elements. <P>SOLUTION: The light guide plate of this invention has a cutout corner part, an incident surface which is the side surface of the cutout corner part, an emitting surface adjoining this incidence surface, and a reflection surface facing the emitting surface. Fine V-shaped projection arcs are formed projecting from the light guide plate on the reflection surface. Those fine V-shaped projection arcs has a common center, are curved toward the incident surface, and are the thicker and the larger, the closer to the incident surface. The combination of the light guide plate and a light source has a merit of high brightness and even distribution of the emitted light while realizing the effect of a traditional back light module. This invention also provides a back light module using this light guide plate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light guide plate and a backlight module used in the field of liquid crystal display, and more particularly to a sidelight type light guide plate and a backlight module.

  The light guide plate is an important part of a liquid crystal display backlight module system including an incident surface, a reflective surface, an output surface and several side surfaces, and is a point light source (for example, a light emitting diode) or a linear light source (for example, a cold cathode tube). ) Is emitted from one plane, and the luminance and uniformity of the panel are increased. Usually, the light guide plate is made of synthetic resin, and is divided into a flat plate type, a wedge type and a curved surface type according to the shape of the substrate.

  The light beam incident on the light guide plate is propagated in the light guide plate by the total reflection principle, and when the light beam enters the fine mechanism on the surface of the light guide plate, the total reflection condition is broken so that the light beam is emitted from the light guide plate. Exits from. The light guide plate emits light uniformly by a fine mechanism with different density and density. The technology for producing the fine mechanism of the light guide plate is divided into both a printing type and a non-printing type. The printing type uses a printing plate to manufacture a fine mechanism by printing ink on a light guide plate. The non-printing type is a method in which a mold having a fine mechanism is directly molded by an injection molding technique, which is easy to manufacture, has high accuracy, and has been a mainstream technique for manufacturing a light guide plate until now. It was. Non-printing manufacturing methods can be divided into chemical etching, laser direct copying, and precision machining.

  As a liquid crystal display (LCD) is widely applied to the fields of mobile phones, car displays, personal digital assistants (PDAs), televisions, etc., a backlight technology mainly using a light guide plate However, severe demands have been made in the areas of high brightness, low cost, light weight, and the like.

  As shown in FIG. 1, the conventional backlight module 10 includes optical elements such as a light source 11, a light guide plate 13, a reflection plate 12, a diffusion plate 14, and a gloss plate 15 for increasing luminance. The reflection plate 12 reflects light rays that are not scattered to the light guide plate 13. The diffusing plate 14 uniformly diffuses light rays and prevents the occurrence of spots formed from the fine mechanism of the light guide plate. The glossy plate 15 that increases the brightness can collect light rays and increase the brightness.

  However, when viewed from the light output angle, the design of the light guide plate does not consider controlling the angle of the light output. Therefore, the light beam from the exit surface of the light guide plate is not perpendicular to the exit surface. For such light rays, an optical element such as a diffuser plate 14 and a glossy plate 15 for increasing the brightness must be used, so that the light enters the LCD perpendicular to the exit surface and satisfies the actual use requirement. Become.

  2 and 3 show a backlight module 20 posted in Patent Document 1, and a light guide plate 21 having a plurality of recesses 22 that scatter light rays on the bottom surface thereof, and a center of the side surface of the light guide plate 21. The light source 23 arrange | positioned, the diffusion plate 24 arrange | positioned above the light-guide plate 21, and the prism sheet 25 arrange | positioned below the light-guide plate 21 are included. The prism sheet 25 has a V-shaped convex portion 26 on the lower surface, and a reflective film 27 is formed on the lower surface. The concave portions 22 are distributed in a circular arc shape with the light source 23 at the center, and the distribution becomes denser as the distance from the light source 23 increases (as shown in FIG. 3). In view of the above-described configuration, the backlight module 20 excludes the light guide plate 21 and the prism sheet 25 is formed by plating a film below the light guide plate in order to allow the light emitted from the backlight module 20 to enter the liquid crystal panel vertically. At the same time, and the diffusion plate 24 must be disposed above the light guide plate 21, so that the configuration of the backlight module 20 is complicated and the light source 23 is disposed at the center of the side surface of the light guide plate 21. It is inconvenient to adjust the uniformity of the light beam emitted from the light guide plate.

  4 and 5 show a backlight module 30 posted in Patent Document 2, a rectangular light guide plate 31 having a plurality of recesses 32 distributed discontinuously on the bottom surface thereof, and a light guide plate. LED light source 33 disposed at the apex angle of 31, scattering prism sheet 34 disposed above light guide plate 31, and reflector 35 disposed below light guide plate 31. The recesses 32 are distributed in an arc shape with the light source 33 at the center, and the distance between adjacent arcs is equivalent (as shown in FIG. 5). The configuration of the backlight module 30 is also complicated, and in addition to the light guide plate 31, it is necessary to have a reflecting plate 35 and a scattering prism sheet 34 having the effect of a prism and a diffusing plate.

  6 and 7 show a backlight module 40 posted in Patent Document 3, a rectangular light guide plate 41, an LED light source 43 arranged at the apex angle of the light guide plate 41, and the light guide plate 41. A prism sheet 44 disposed above and a reflecting plate 45 disposed below the light guide plate 41 are included. On the bottom surface of the light guide plate 41, a plurality of V-shaped concave portions 42 distributed in an arc shape centering on the LED light source 43 are formed. The distance between adjacent V-shaped recesses 42 is equal. However, since the backlight module 40 needs to have a reflecting plate 45 and a prism 44 in addition to the light guide plate 41, the configuration is complicated, and the concave portion 42 arranged on the bottom surface of the light guide plate 41 has a uniform outgoing light beam. It is inconvenient to adjust sex.

Therefore, there is a need to provide a light guide plate that emits an emitted light beam vertically from an exit surface without arranging an optical element, and a backlight module that uses the light guide plate.
US Patent Application Publication No. 2003/0058382 US Patent Application Publication No. 2003/0137824 US Patent Application Publication No. 2003/0169584

  The first object to be solved by the present invention is to provide a light guide plate that emits an emitted light beam vertically from an exit surface without arranging an optical element.

  The second object of the present invention is to provide a backlight module using the light guide plate.

  In order to achieve the first object, the present invention provides a light guide plate having a corner cut portion. The light guide plate includes one corner cut portion, an incident surface that is a side surface of the corner cut portion, an exit surface adjacent to the entrance surface, and a reflective surface facing the exit surface. A plurality of V-shaped fine mechanisms that protrude outside the light guide plate and are arranged in an arc shape are formed on the reflecting surface, and the V-shaped fine mechanisms have the same center and are incident on the incident surface. The V-shaped fine mechanism is bent, and the larger the distance from the incident surface, the denser the arrangement and the larger the size.

  In order to achieve the second object, the present invention provides a backlight module. The backlight module includes a light source and one corner cut portion, an incident surface that is a side surface of the corner cut portion, an exit surface adjacent to the entrance surface, and a reflective surface facing the exit surface. Is provided. A plurality of V-shaped fine mechanisms that protrude outside the light guide plate and are arranged in an arc shape are formed on the reflecting surface, and the V-shaped fine mechanisms have the same center and are incident on the incident surface. The V-shaped fine mechanism is bent, and the larger the distance from the incident surface, the denser the arrangement and the larger the size.

  In the light guide plate provided by the present invention, compared to the prior art, the design of the V-shaped micromechanism arrangement on the reflecting surface allows the light emitted from the light guide plate to be emitted more perpendicularly to the light emitting surface, and the light energy. The amount of usage increases. The backlight module composed of the light guide plate and the line light source having high luminance has good luminance. In the configuration, optical elements such as a reflection plate, a diffuser plate, and a gloss plate for increasing luminance are used. Since it can be omitted, the configuration is simplified and the performance is improved. The present invention can control the outgoing angle of the outgoing light beam by adjusting the angle of the V-shaped fine mechanism.

  The present invention can control the uniformity of the brightness of the emitted light by adjusting the size of the V-shaped fine mechanism and the density of the arrangement.

  Next, the light guide plate and the backlight module of the present invention will be described in detail with reference to the drawings and examples.

  Referring to FIGS. 8 and 9, the first embodiment of the present invention provides a light guide plate 50 that is a square flat plate with a vertex angle (corner cut portion). The light guide plate 50 is close to the light source 51, an incident surface 52 that is a side surface of a corner cut portion, an output surface 53 that is an upper surface of the light guide plate 50 and is adjacent to the incident surface 52, and the output surface 53. And a reflective surface 54 facing each other. The light guide plate 50 of this embodiment is made of, for example, polymethyl methacrylate (PMMA) and used for a 14.1-inch liquid crystal display. The vertex angle to be cut is an isosceles triangle. The light source 51 of the present embodiment can employ a light emitting diode.

  A plurality of V-shaped fine mechanisms 540 are formed on the reflecting surface 54 so as to protrude outside the light guide plate 50 and to be arranged in an arc shape centering on the apex of the corner cut portion. As shown in FIG. 10, the V-shaped fine mechanism 540 has an apex angle θ3 in the range of 40 to 95 degrees, and has a first base angle θ1 and a second base angle θ2 formed with the plane to which the reflecting surface 54 belongs. The ranges are 70 to 90 degrees and 15 to 50 degrees, respectively. In this embodiment, it is desirable that the apex angle θ3 of the V-shaped fine mechanism 540 is 62 degrees, and the first base angle θ1 and the second base angle θ2 are 81 degrees and 37 degrees, respectively. desirable.

  In order to improve the uniformity of the emitted light, the V-shaped fine mechanism 540 is arranged so that the size increases from the small to the large as the distance from the incident surface 52 increases. That is, the V-shaped fine mechanism 540 decreases as the distance from the light source increases, and the V-shaped fine mechanism 540 increases as the distance from the light source increases. Further, the distance D between adjacent V-shaped fine mechanisms 540 is equal. That is, the distances between the intersections of the first base angle θ1 of the adjacent V-shaped fine mechanism 540 approaching the incident surface 52 and the reflecting surface 54 are equal. The distance D is equal to the width d of the largest fine mechanism 540. The method of increasing the size of the fine mechanism 540 is usually designed according to a non-linear rule and according to the requirement for the uniformity of the luminance of the emitted light and the characteristics of the material of the light guide plate.

  The range of the width d of the V-shaped fine mechanism 540 is 1 to 300 μm. With this size, the V-shaped fine mechanism 540 of the light guide plate is difficult to see with the naked eye through the liquid crystal display. The diffuser plate in the light module can be omitted. As the level of processing technology increases, the width d should be smaller than 1 μm. In the light guide plate 50, if the brightness of the transmitted light in the local area is high, the size and arrangement density of the V-shaped fine mechanisms 540 can be reduced. In the light guide plate 50, the size and arrangement density of the V-shaped fine mechanisms 540 can be increased if the brightness of the transmitted light in the local area is low.

  In order to increase the utilization rate of light energy, a reflection film (not shown) can be designed on the reflection surface 54, and this reflection film is a metal film or a derivative film, such as an aluminum plating or a silver plating. The reflective surface 54 and the protruding V-shaped fine mechanism 540 can have high reflectivity through a technique of plating a film. The three side surfaces excluding the incident surface 52 should also have a high reflectance, which can be realized by plating the reflective film.

  A plurality of bent V-shaped fine mechanisms on the reflecting surface of the light guide plate of the present invention have the same center, but there is no special requirement for the position of the center, and a plurality of bent V-shaped fine mechanisms are It only needs to bend with respect to the incident surface.

  Referring to FIG. 11, a plurality of bent V-shaped fine mechanisms 840 on the reflecting surface of the light guide plate 80 according to the second embodiment of the present invention have the same center, and the center is on the left side of the light source 81. . A plurality of bending V-shaped fine mechanisms 840 are bent with respect to the incident surface 82 of the light guide plate 80, completely surround the incident surface 82, and all light rays incident from the incident surface 82 are bent at the reflection surface. Reflected by the V-shaped fine mechanism 840.

  Referring to FIG. 12, a plurality of bent V-shaped fine mechanisms 940 on the reflection surface of the light guide plate 90 according to the third embodiment of the present invention have the same center, and the center is on the right side of the light source 91. . The plurality of bent V-shaped fine mechanisms 940 are bent with respect to the incident surface 92 of the light guide plate 90, completely surround the incident surface 92, and all light rays incident from the incident surface 92 are reflected on the reflection surface. Reflected by the bent V-shaped fine mechanism 940.

  Referring to FIG. 13, the light guide plate 100 according to the fourth embodiment of the present invention is different from the light guide plate 80 according to the first embodiment in that a curved V-shape on a reflection surface (not shown) of the light guide plate 100 is used. The fine mechanisms 104 are arranged along non-continuous curves.

  The light guide plates of the second, third, and fourth embodiments have the advantage that the emitted light is emitted perpendicularly to the emission surface without arranging optical elements, and the brightness is high and the uniformity of the emitted light is good.

  In order to improve the uniformity of incident light from the light source, in the present invention, fine mechanisms arranged periodically can be arranged on the incident surface of the light guide plate. Referring to FIG. 14, the light guide plate 110 according to the fifth embodiment of the present invention has V-shaped micro-mechanisms 114 periodically arranged in the vertical direction on the incident surface 112 of the light guide plate according to the first embodiment. To do. The V-shaped micromechanism 114 has an elongated shape having the same isosceles triangle in cross section, a vertex angle range of 50 to 150 degrees, and a height of 500 μm or less. A suitable periodically arranged V-shaped fine mechanism 114 provided by the present embodiment has an apex angle of 120 degrees and a width of 0.2 μm.

  As shown in FIG. 15, the micro mechanisms arranged on the incident surface of the light guide plate provided by the present invention are V-shaped micro mechanisms 121 arranged densely and periodically, and periodically arranged without being continuous. The V-shaped fine mechanism 123, the semi-cylindrical fine mechanism 125 arranged densely and periodically, and other periodically arranged fine mechanisms. The fine mechanism can also improve the uniformity of incident light from the light source.

  Next, the light guide plate provided by each embodiment of the present invention will be described in detail with reference to test data.

  FIG. 16 is an angle distribution diagram of the emitted light from the light guide plate of the single side illumination in which the fine mechanism is arranged only on the reflection surface in the first embodiment, and it can be seen that the amount of energy is emitted from the center.

  FIG. 17 shows a normalized light intensity curve along the horizontal axis (direction in which the light beam travels) and the vertical axis (direction perpendicular to the direction in which the light beam travels) in which the fine mechanism is arranged only on the reflecting surface in the first embodiment. It is a figure and this represents the situation of the angle distribution of the emitted light. As can be seen from FIG. 17, if the angle in the two directions along the horizontal axis and the vertical axis is −25 degrees to +25 degrees, most of the light beams are emitted perpendicularly to the emission surface of the light guide plate. Therefore, the light guide plate and the light source provided by the present invention can satisfy the requirement of the emission angle of the traditional backlight module.

  FIG. 18 is an angle distribution diagram of light rays emitted from a light guide plate in which fine mechanisms are arranged on the reflecting surface and the incident surface in the fifth embodiment. When FIG. 18 is viewed, the light emission angles gather around the center. I understand.

  FIG. 19 shows the normalized light intensity along the horizontal axis (the direction in which the light beam travels) and the vertical axis (the direction perpendicular to the direction in which the light beam travels) in the fifth embodiment in which fine mechanisms are arranged on the reflecting surface and the incident surface. It is a curve diagram, which represents the situation of the angular distribution of the outgoing light. As can be seen from FIG. 19, if the angle in the two directions along the horizontal axis and the vertical axis is −25 degrees to +25 degrees, most of the light beams are emitted perpendicularly to the exit surface of the light guide plate. . Therefore, the light guide plate and the light source provided by the present invention can satisfy the requirement of the emission angle of the traditional backlight module.

  The light guide plate provided by the present invention can also be designed in a wedge shape. The backlight module comprising the light guide plate and the point light source has the advantages of high brightness and good uniformity. As the material of the light guide plate, a synthetic resin material such as polycarbonate (PC) may be adopted in addition to polymethyl methacrylate.

  In the light guide plate provided by the present invention, the design of the V-shaped fine mechanism on the reflection surface allows the light emitted from the light guide plate to be emitted more favorably perpendicular to the output surface, and the amount of light energy used is increased. The backlight module composed of the light guide plate and the point light source has good luminance, and the configuration can be omitted because the optical elements such as the reflection plate, diffuser plate, and glossy plate for increasing the luminance of the traditional backlight module can be omitted. Becomes easier and the performance is improved. The present invention can control the outgoing angle of the outgoing light beam by adjusting the angle of the V-shaped fine mechanism.

It is a block diagram of a traditional sidelight type backlight module. FIG. 10 is a cross-sectional configuration diagram of a backlight module posted in Patent Document 1. It is a block diagram which arranges the fine mechanism of the reflective surface of the light-guide plate of FIG. FIG. 12 is a cross-sectional configuration diagram of a backlight module posted in Patent Document 2. It is a block diagram which arranges the fine mechanism of the reflective surface of the light-guide plate of FIG. FIG. 10 is a cross-sectional configuration diagram of a backlight module posted in Patent Document 3. It is a block diagram which arranges the fine mechanism of the reflective surface of the light-guide plate of FIG. It is a bottom view of the light guide plate of the first embodiment of the present invention. It is a schematic sectional drawing which follows the VI-VI line of FIG. It is an enlarged view of the local VII of FIG. It is a bottom view of the light guide plate of the second embodiment of the present invention. It is a bottom view of the light-guide plate of the 3rd Example of this invention. It is a bottom view of the light-guide plate of 4th Example of this invention. It is a block diagram of the entrance plane of the light-guide plate of 5th Example of this invention. It is the schematic of three types of fine mechanisms of the entrance plane of the light-guide plate of this invention. It is an arrangement | sequence diagram of the angle of the emitted light from the light-guide plate of the 1st Example of this invention. It is a curve figure of the normalized light intensity along the X-axis and the Y-axis in the first embodiment of the present invention. It is an arrangement | sequence diagram of the angle of the emitted light from the light-guide plate of 5th Example of this invention. It is a curve figure of the normalized light intensity along the X-axis and the Y-axis in the fifth embodiment of the present invention.

Explanation of symbols

10, 20, 30, 40 Backlight module 104, 114, 121, 123, 540, 840, 940 V-shaped fine mechanism 11, 23, 33, 43 Light source 12, 35, 45 Reflector 125 Fine structure of semi-cylinder 13, 21, 31, 41 Light guide plate 14, 24 Diffuser plate 15 Gloss plate 22, 32, 42 Concave 25, 34, 44 Prism sheet 26 V-shaped convex part 27 Reflective film 50, 80, 90, 100, 110 Optical plate 51, 81, 91, 111 Light source 52, 82, 92, 112 Incident surface 53 Outgoing surface 54 Reflecting surface

Claims (6)

One corner cut,
An incident surface which is a side surface of the corner cutting portion;
An exit surface adjacent to the entrance surface;
In the light guide plate including the output surface and the reflective surface facing the output surface, the reflective surface is formed with a plurality of V-shaped fine mechanisms protruding outside the light guide plate and arranged in an arc shape. A light guide plate characterized in that the mechanisms have the same center and bend to the incident surface, and the V-shaped fine mechanism is more densely arranged and larger in size as the distance from the incident surface increases.   2. The light guide plate according to claim 1, wherein the V-shaped fine mechanisms arranged in an arc shape are continuous or non-continuous.   The light guide plate according to claim 1, wherein fine mechanisms arranged periodically in the vertical direction are arranged on the incident surface.   The fine mechanism is a V-shaped fine mechanism that is densely and periodically arranged, a V-shaped fine mechanism that is periodically arranged without being continuous, or a cylindrical convex fine mechanism that is periodically arranged. The light guide plate according to claim 3.   The light guide plate according to claim 1, wherein a reflection film is plated on the reflection surface. A light source and a single corner,
An incident surface which is a side surface of the corner cutting portion;
An exit surface adjacent to the entrance surface;
In a backlight module comprising a light guide plate including a reflective surface facing the emission surface, a plurality of V-shaped fine mechanisms that protrude outside the light guide plate and are arranged in an arc shape are formed on the reflective surface, The V-shaped fine mechanism has the same center and bends to the incident surface, and the V-shaped fine mechanism is characterized in that the larger the distance from the incident surface, the denser the arrangement and the larger the size. Backlight module to do.