JP2007140466A - High luminance light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high luminance light guide plate in which a diffusion point formed on a light emitting face created for the first time can immediately vary and correct quality and uniformity without adjusting the cell arrangement of a diffusion pattern, a speedy plate change and a core manufacturing are made possible, thus the manufacturing cost of a metallic mold for the light guide plate is reduced. <P>SOLUTION: In the plate-shaped light guide plate (10) formed of a transparent resin having a high refractive index, one face of the light guide plate (10) serves as a light incident face (11), the front face of the light guide plate (10) serves as a light emitting face (12), the back face of the light emitting face (12) serves as a reflecting face (13), a diffusion pattern is formed by a plurality of recessed individual cells (14) on the reflecting face (13), and a plurality of projected diffusion points (15) showing the shape of a substantially hemispherical dome are arranged on the light emitting face (12). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to parts of a surface light source device, and specifically refers to a high-intensity light guide plate.

  A known surface light source device mainly includes a light guide plate, a light emitting unit, and a reflector structure. Among them, the light guide plate is formed of a transparent resin having a high refractive index, and a diffusion pattern (pattern) composed of cells is processed and formed on the back surface thereof. One side of the light guide plate is used as a light incident surface, and the light emitting portion faces the light incident surface, thereby projecting light rays and entering the light guide plate. The reflection plate is attached to a light guide plate having a back surface of a diffusion pattern and a sheet body having a high reflectance.

  The light emitting unit passes through the light incident surface, and the light incident on the inside of the light guide plate is totally reflected between the front and back surfaces of the light guide plate, and the light is confined inside the light guide plate, and is far from the light emitting unit. Transmitted away. In this way, when the light beam transmitted through the light guide plate is projected to the back surface of the light guide plate, a part of the light is totally reflected in the direction of the surface of the light guide plate (this is the light exit surface) by the diffusion pattern. At this time, the light beam reflected toward the light exit surface at an angle smaller than the total reflection critical angle passes through the light exit surface and exits from the outside of the light guide plate. Light rays that are not subjected to total reflection of the diffusion pattern of another portion are reflected by the reflecting plate, return to the inside of the light guide plate, and are confined in the light guide plate again, and energy loss on the back surface of the light guide plate is reduced by reflection of the reflecting plate.

  Since the light emitted from the light exit surface of the light guide plate is emitted from the medium having a large refractive index to the medium having a small refractive index, the light beam is emitted in a direction away from the normal line of the light exit surface. Along the light incident surface, the width direction is defined as the X-axis, the direction perpendicular to the light incident surface is defined as the Y-axis, and the direction perpendicular to the light emission surface is defined as the Z-axis. The light that passes and exits becomes a light having an elongated directional pattern substantially along the Y-axis direction. The effective viewing angle of the human eye is 5 ° to 10 °, and the emitted light outside this viewing angle range cannot be visually observed. Therefore, the light emitted through the light emitting surface is completely received by the naked eye. Can not do it. Under this kind of condition, when viewed from the direction perpendicular to the light exit surface (Z-axis direction), the luminance of the light emitted from the light guide plate obtained by visual observation is relatively low, and the luminous efficiency of the light emitting part is disadvantageous. Therefore, many known surface light source devices are installed with a prism above the light exit surface of the light guide plate, and the light emitted from the light exit surface is concentrated near the Z-axis direction through the prism and visually observed. Increase the light intensity obtained.

  As can be seen, the directivity pattern of the light beam that passes through and exits the light exit surface can be made closer to the light exit surface direction (Z-axis direction) along the direction perpendicular to the light exit surface. Enter the effective viewing angle. There is no need to rely on the use of prisms, the brightness of the light emitted from the light guide plate in the Z-axis direction can be increased, the luminous efficiency of the light emitting part can be increased, and the volume of the surface light source device and its manufacturing cost can be reduced. It is.

  In other respects, a known surface light source device uses a light-emitting part of a light-emitting unit as a light source, and the light-emitting parts are generally of two types: a cold-cathode tube lamp (CCFL) and a light-emitting diode (LED). Among them, a light emitting part that uses LEDs as light sources forms a plurality of point light sources by arranging a plurality of LEDs. The point light source is a light beam that passes through the light incident surface and is projected radially toward the inside of the light guide plate. A well-known light guide plate constitutes a cell having a diffusion pattern, and when viewed from the Z-axis direction, the boundary surface of the refraction and reflected light is parallel to the light incident surface. As described above, when the light beam transmitted in the light guide plate is projected to the diffusion pattern, only a part of the light beam is totally reflected by the diffusion pattern toward the light emission surface, and the light mixing distance between the LEDs causes the light and darkness to be reflected. Easy to make alternating stripes. In particular, in the light guide plate with a mirror pattern, the situation of these bright and dark alternating stripes is more severe. As clear bright lines and dark fringes are formed, it is necessary to diffuse the light from the exit light guide plate using a diffuser plate. Furthermore, it affects the light rays of the exit light guide plate, lowers the brightness in the Z-axis direction, and is disadvantageous to the light emission efficiency of the light emitting section.

  In order to solve the above-mentioned problems of the known light guide plate, the present applicant has applied for an invention of a high-intensity light guide plate (Patent Document 1). Please refer to the instructions. This previous invention effectively increased the brightness in the vertical direction relative to the light exit surface of the light emitted from the light guide plate by the diffusion pattern created for the first time, and further advanced to improve the luminous efficiency of the surface light source device. Reduce device volume and manufacturing costs. In addition, the light emitted from the light guide plate is distributed on the average by the light exit surface, and further bright lines and dark fringes are avoided.

  When it is desired to manufacture a molding die that has been invented before, it is necessary to first design the specific size and distribution of cells in the diffusion pattern. Based on the design, a mirror core with a plurality of convex points formed on the surface is manufactured. Next, the core is placed in a mold, and the reflection surface is formed as a mold surface. When a light guide plate prototype is produced by an injection operation using the convex points of the core, the reflecting surface distributes a plurality of cells and forms a diffusion pattern. After that, a test is performed on the prototype, and it is verified whether the expected effect such as achievement of high brightness and no bright line has been achieved. If the effect is less than ideal, the previous design and specular core must often be discarded. The cell size and distribution must be redesigned, the core must be remanufactured, the prototype must be injected and verified. By repeatedly changing the plate, making a prototype, and verifying it, it is possible to provide a light guide plate molding die whose function expression meets the requirements for mass production only for the first time.

  In general, the distribution of cells has a direct influence on the generation of bright lines and dark fringes when light passes through the light exit surface. Generally, in the industry, evaluation of whether or not it is balanced against light and dark is called quality. By adjusting the cell distribution, the quality and uniformity of the backlight module can be modified to achieve the expected state. However, in this method, when manufacturing a mass-production mold, it is sometimes necessary to repeat the above-described manufacturing process such as plate change, trial manufacture, and verification 20 times. In other words, every time the plate is changed, it means that the mirror core is discarded and remanufactured. However, the production of the mirror core has high precision requirements and high technical level, and the production cost is also very high. The more times the plate is changed repeatedly, the higher the cost of the specular core being consumed, and the overall cost and working time of mold production are considerable when procedures such as prototyping and verification are added.

  Therefore, in order to revise the quality and uniformity of the previous invention and to revise problems that are not ideal in terms of cost and work time at the time of mold production, the inventor of this proposal has repeatedly conducted active research and creation, and many After passing through these tests, the present invention was finally obtained that was innovative and could be provided for industrial use.

Taiwan Patent No. 094125793 Specification

  The main object of the present invention is to provide a high-intensity light guide plate, in which the diffusion points formed on the light emitting surface created for the first time do not need to adjust the cell arrangement of the diffusion pattern, and immediately improve the quality and level. The change can be corrected once, the plate can be changed quickly, and the core can be manufactured, thereby reducing the manufacturing cost of the light guide plate mold.

  For this reason, the high-intensity light guide plate of the present invention has a light incident surface on one side of the light guide plate and a light emission surface on the surface of the light guide plate among the plate bodies formed of the transparent resin having a high refractive index. . The back surface of the light guide plate facing the light exit surface is used as a reflection surface, and a plurality of cells recessed in the light guide plate and the reflection surface form a diffusion pattern.

  In the light guide plate, a plurality of diffusion points protrude from the light exit surface, and each diffusion point is disposed on the light exit surface, thereby improving the quality and uniformity, thereby reducing the manufacturing cost of the light guide plate mold.

The invention of claim 1 is a kind of high-intensity light guide plate, the light guide plate being a plate formed of a transparent resin having a high refractive index, of which one side of the light guide plate is a light incident surface, and The surface is a light emitting surface, and the light guide plate has a back surface opposite to the light emitting surface as a reflective surface, and the light guide plate has a plurality of cells recessed in the reflective surface to form a diffusion pattern,
The light guide plate is characterized in that a plurality of diffusion points protrude from the light exit surface, and each diffusion point is disposed on the light exit surface, thereby improving the quality and uniformity, thereby reducing the manufacturing cost of the light guide plate mold. High brightness light guide plate.
The invention according to claim 2 is the high-intensity light guide plate according to claim 1, wherein the diffusion point has a substantially hemispherical dome shape.

  The present invention provides a high-intensity light guide plate, which means that the diffusion point formed on the light emitting surface created for the first time does not need to adjust the cell arrangement of the diffusion pattern, and immediately changes and corrects the quality and uniformity. It is possible to speedily change the plate and manufacture the core, thereby reducing the manufacturing cost of the light guide plate mold.

  See FIG. The high-intensity light guide plate (10) of the present invention is a plate body formed of a transparent resin having a high refractive index. One surface of the light guide plate (10) is a light incident surface (11), and the surface of the light guide plate (10) is light. Let it be an emission surface (12). The back surface of the light guide plate (10) facing the light exit surface (12) is the reflective surface (13), and is parallel to the light exit surface (12). In the light guide plate (10), a plurality of cells (14) are recessed in the reflecting surface (13) to form a diffusion pattern. This part is the same as the previous invention, and its configuration will not be described in detail. See FIGS. 2-4. The light guide plate (10) has a plurality of diffusion points (15) projecting from the light emission surface (12), each diffusion point (15) having a substantially hemispherical dome shape, which is based on the light trajectory. ) Is disposed on the light exit surface (12). The light beam emitted from the light guide plate (10) is distributed to the average, avoids the formation of bright lines and dark fringes, further improves quality and uniformity, and lowers the manufacturing cost of the light guide plate mold.

  See FIG. 5 and FIG. When the light beam passes through the light exit surface (12), the light trajectory is guided by the surface of the diffusion point (15) and is diffused and projected toward a wide surface area, thereby avoiding the formation of bright lines and dark fringes. When manufacturing the molding die of the present invention, it is not necessary to adjust the arrangement of the cells (14) constituting the diffusion pattern many times to change the plate to the best quality and uniformity state. Even if the quality and uniformity are merely as shown in FIG. 5, L indicates a light area and D indicates a dark area. However, if the formation of the diffusion point (15) is further blended, the formation of bright lines and dark fringes can be avoided immediately, and the effect of improving quality and uniformity can be achieved (as shown in FIG. 6). FIG. 6 shows a luminance distribution state. The luminance gradually decreases from the central portion of the light guide plate toward the outer periphery, and exhibits ideal quality and uniformity. Thereby, the repetition change of the mirror surface core used for shaping | molding of a diffusion pattern, and the frequency | count of making a prototype can be reduced significantly. In an actual test, the cell distribution of the diffusion pattern can increase the light emission angle in the Z-axis direction, and the distribution state of the diffusion point (15) is determined based on the light trajectory passing through the light exit surface. In this way, it is only necessary to repeat the change and prototype a mirror core that requires about 3 to 5 diffusion pattern moldings. Further, when a semi-specular core for molding a diffusion point is blended and manufactured, and the surface of the concave hole formed by the core is used as a mold surface for molding the light emitting surface, it is advantageous when the light guide plate is injection molded. The light guide plate forms its diffusion point (15) on the light exit surface, but these cores immediately mold the light exit surface (12) and the diffusion point (15) by making the surface a quasi-specular core close to the specular state. Adapted to the later required functions, the quasi-mirror core is clearly lower in precision and technical level in fabrication than the mirror core, and its production cost is relatively lower than the mirror core required to mold the diffusion pattern. In addition, these quasi-mirror cores can be quickly changed to save significant development time. Therefore, according to the present invention, the formation of the diffusion point (15) can speedily correct the quality and uniformity, and the overall cost of manufacturing the light guide plate mold for mass production can be greatly reduced. Effectively reduce the work time required for mold development.

1 is a cross-sectional view of a preferred embodiment of the present invention. It is a local expanded sectional view of the diffusion point part of FIG. It is a distribution state diagram of a diffusion point of a preferred embodiment of the present invention. FIG. 4 is an enlarged view of a diffusion point portion in FIG. 3. It is a luminance distribution state figure of the light-guide plate which has not formed the diffusion point. It is a luminance distribution state diagram of a preferred embodiment of the present invention.

Explanation of symbols

10 Light guide plate 11, 12, 13 Light incident surface 14 Cell 15 Diffusion point

Claims (2)

In a kind of high-intensity light guide plate, the light guide plate is a plate formed of a high refractive index transparent resin, of which one side of the light guide plate is a light incident surface, and the surface of the light guide plate is a light emitting surface, The light guide plate has a reflective surface on the back surface facing the light exit surface, and the light guide plate has a diffusion pattern formed by a plurality of cells recessed in the reflection surface.
The light guide plate is characterized in that a plurality of diffusion points protrude from the light exit surface, and each diffusion point is disposed on the light exit surface, thereby improving the quality and uniformity, thereby reducing the manufacturing cost of the light guide plate mold. High brightness light guide plate. 2. The high-intensity light guide plate according to claim 1, wherein the diffusion point has a substantially hemispherical dome shape.

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