Patent Application
20080137203
1. Field of the Invention
The present invention relates to an optical plate for use in, for example, a backlight module, the backlight module typically being employed in a liquid crystal display (LCD).
2. Discussion of the Related Art
The lightness and slimness of LCD panels make them suitable for use in a wide variety of electronic devices such as personal digital assistants (PDAs), mobile phones, portable personal computers, and other electronic appliances. Liquid crystal is a substance that does not itself emit light. Rather, the liquid crystal relies on light from a light source in order to display data and images. In a typical LCD panel, a backlight module powered by electricity supplies the needed light.
In use, light rays from the lamps 12 enter the prism sheet 15 after being scattered in the light diffusion plate 13. The light rays are refracted and concentrated by the V-shaped structures of the prism sheet 15 so as to increase brightness of light illumination, and finally propagate into the LCD panel (not shown) disposed above the prism sheet 15. The brightness can be improved by the V-shaped structures, but the viewing angle may be narrowed. In addition, even though the light diffusion plate 13 and the prism sheet 15 abut each other, a plurality of air pockets still exist at the boundary between them. When the backlight module 10 is in use, light passes through the air pockets, and some of the light undergoes total reflection at the air pockets. As a result, the light energy utilization ratio of the backlight module 10 is reduced.
Therefore, a new optical means is desired in order to overcome the above-described shortcomings. A backlight module utilizing such optical means is also desired.
In one aspect, an optical plate includes a first transparent layer, a second transparent layer and a light diffusion layer. The light diffusion layer is between the first and second transparent layers. The light diffusion layer, the first transparent layer and the second transparent layer are integrally formed. The light diffusion layer includes a transparent matrix resin, and a plurality of diffusion particles dispersed in the transparent matrix resin. The first transparent layer includes a plurality of first spherical depressions at an outer surface thereof that is farthest from the second transparent layer. The second transparent layer includes a plurality of second spherical depressions at an outer surface thereof that is farthest from the first transparent layer.
Other novel features and advantages will become more apparent from the following detailed description, when taken in conjunction with the accompanying drawings.
The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present optical plate and backlight module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and all the views are schematic.
Reference will now be made to the drawings to describe preferred embodiments of the present optical plate and backlight module, in detail.
Referring to
In the illustrated embodiment, each first spherical depression 211 has a sub-hemispherical shape. Thus a maximum depth H1 of the first spherical depression 211 is less than a radius R1 of the first spherical depression 211. The first spherical depressions 211 are arranged separately from one another at the outer surface 210 in a matrix. In order to achieve high quality optical effects, the radius R1 of each first spherical depression 211 is preferably in a range from about 0.01 millimeters to about 3 millimeters. The maximum depth H1 of each first spherical depression 211 is preferably at least 0.01 millimeters. In other embodiments, the maximum depth H1 can be as much as R1. That is, 0.01 mm≦H1≦R1. Thus, the maximum depth H1 is preferably in a range from about 0.01 millimeters to about 3 millimeters. A pitch D1 between adjacent first spherical depressions 211 is preferably in the following range: R1/2≦D1≦4R1. That is, the pitch D1 is preferably in the range from about 0.005 millimeters to about 12 millimeters.
The second spherical depressions 231 are configured for collimating emitting light to a certain extent, and thus improving a brightness of light illumination. In the illustrated embodiment, each second spherical depression 231 is a hemispherical depression. The second spherical depressions 231 are arranged separately from one another at the outer surface 230 in a matrix. In order to achieve high quality optical effects, a radius R2 of each second spherical depression 231 is preferably in a range from about 0.01 millimeters to about 3 millimeters. A maximum depth H2 of each second spherical depression 231 is preferably in the following range: 0.01 millimeters≦H2≦R2. That is, the maximum depth H2 is preferably in a range from about 0.01 millimeters to about 3 millimeters. A pitch D2 between two adjacent second spherical depressions 231 is preferably in the following range: R2/2≦D2≦4R2. That is, the pitch D2 is preferably in a range from about 0.005 millimeters to about 12 millimeters. In the illustrated embodiment, the maximum depth H2 is equal to R2, and the pitch D2 is greater than 2R2. In alternative embodiments, the second spherical depressions 231 can be substantially the same as the first spherical depressions 211. Further, in the illustrated embodiment, the first spherical depressions 211 are arranged in one-to-one correspondence with the second spherical depressions 231.
A thickness of each of the first transparent layer 21, the light diffusion layer 22, and the second transparent layer 23 can be equal to or greater than 0.35 millimeters. In a preferred embodiment, a combined thickness of the first transparent layer 21, the light diffusion layer 22, and the second transparent layer 23 is preferably in the range from about 1.05 millimeters to about 6 millimeters. Each of the first transparent layer 21 and the second transparent layer 23 is preferably made of one or more transparent matrix resins selected from the group including polyacrylic acid (PAA), polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), methylmethacrylate and styrene copolymer (MS), and any suitable combination thereof. It should be pointed out that the materials of the first transparent layer 21 and the second transparent layer 23 can be the same or can be different.
The light diffusion layer 22 includes a transparent matrix resin 221, and a plurality of diffusion particles 222 dispersed in the transparent matrix resin 221. In a typical embodiment, the diffusion particles 222 are substantially uniformly dispersed in the transparent matrix resin 221. The light diffusion layer 22 is configured for enhancing uniformity of light output from the optical plate 20. The transparent matrix resin 221 is selected from the group consisting of polyacrylic acid (PAA), polycarbonate (PC), polystyrene (PS), polymethyl methacrylate (PMMA), methylmethacrylate and styrene copolymer (MS), and any suitable combination thereof. The diffusion particles 222 can be made of material selected from the group consisting of titanium dioxide, silicon dioxide, acrylic resin, and any combination thereof. The diffusion particles 222 are configured for scattering light and enhancing a light distribution capability of the light diffusion layer 22. The light diffusion layer 22 preferably has a light transmission ratio in a range from 30% to 98%. The light transmission ratio of the light diffusion layer 22 is determined by a composition of the transparent matrix resin 221 and the diffusion particles 222.
In alternative embodiments, the first and second spherical depressions 211, 231 are not limited to being arranged in a regular matrix. Either or both of the first and second spherical depressions 211, 231 can instead be arranged otherwise. For example, the spherical depressions 231 can be arranged in rows, with the spherical depressions 231 in each row being offset from (staggered relative to) the spherical depressions 231 in each of the adjacent rows. In another example, the spherical depressions 211, 231 may be arranged randomly at the respective outer surface(s). Furthermore, the spherical depressions 211, 231 may be of different sizes and/or of different shapes. For example, a radius of each spherical depression 211, 231 in a predetermined group of spherical depressions 211, 231 may be different (larger or smaller) than a radius of each spherical depression 211, 231 in another predetermined group of spherical depressions 211, 231.
Referring to
In the backlight module 30, when the light from the lamp tubes 32 enters the optical plate 20 via the first transparent layer 21, the light is diffused by the first spherical depressions 211 of the first transparent layer 21. Then the light is further substantially diffused in the light diffusion layer 22. Finally, the light is condensed by the second spherical depressions 231 of the second transparent layer 23 before exiting the optical plate 20. Therefore, a brightness of the backlight module 30 is increased. In addition, because the light is diffused at two levels, a uniformity of the light output from the optical plate 20 is enhanced. Furthermore, since the first transparent layer 21, the light diffusion layer 22, and the second transparent layer 23 are integrally formed together (see above), few or no air or gas pockets exist at the respective common interfaces therebetween. Thus there is little or no back reflection at the common interfaces, and the efficiency of utilization of light rays is increased. Moreover, the optical plate 20 utilized in the backlight module 30 in effect replaces the conventional combination of a diffusion plate and a prism sheet. Thereby, a process of assembly of the backlight module 30 is simplified, and the efficiency of assembly is improved. Still further, a volume occupied by the optical plate 20 is less than a total volume occupied by the conventional combination of a diffusion plate and a prism sheet. Thereby, a volume of the backlight module 30 is reduced.
In the alternative embodiment, when the light from the lamp tubes 32 enters the optical plate 20 via the second transparent layer 23, the uniformity of light output from the optical plate 20 is also enhanced, and the utilization efficiency of light rays is also increased. Nevertheless, light exiting the optical plate 20 via the first transparent layer 21 is different from light exiting the optical plate 20 via the second transparent layer 23. For example, when the backlight module 30 is configured such that the light from the lamp tubes 32 enters the optical plate 20 via the first transparent layer 21, a viewing angle of the backlight module 30 is somewhat larger than that of the backlight module 30 having the light enter the optical plate 20 via the second transparent layer 23.
Referring to
In the above-described embodiments, the first common interface between the light diffusion layer and the first transparent layer is substantially planar, and the second common interface between the light diffusion layer and the second transparent layer is also substantially planar. Alternatively, either or both of the common interfaces can be nonplanar. For example, either or both of the common interfaces can be curved or wavy.
Referring to
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200610201253.0 | Dec 2006 | CN | national |
This application is related to fourteen copending U.S. patent applications, which are: application Ser. No. 11/620,951 filed on Jan. 8, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS”; application Ser. No. 11/620,958, filed on Jan. 8, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND MICRO PROTRUSIONS”; application Ser. No. 11/623,302, filed on Jan. 5, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS”; application Ser. No. 11/623,303, filed on Jan. 15, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application Ser. No. 11/627,579, filed on Jan. 26, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS”; application Ser. No. 11/672,359, filed on Feb. 7, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application Ser. No. 11/716,323, filed on Mar. 9, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application Ser. No. 11/716,140, filed on Mar. 9, 2007, and entitled “THREE-LAYERED OPTICAL PLATE AND BACKLIGHT MODULE WITH SAME”; application Ser. No. 11/716,158, filed on Mar. 9, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application Ser. No. 11/716,143, filed on Mar. 9, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; and application Ser. No. 11/716,141, filed on Mar. 9, 2007, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application serial no. [to be advised], Attorney Docket No. US12890, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; application serial no. [to be advised], Attorney Docket No. US12897, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”; and application serial no. [to be advised], Attorney Docket No. US12898, and entitled “OPTICAL PLATE HAVING THREE LAYERS AND BACKLIGHT MODULE WITH SAME”. In all these copending applications, the inventor is Tung-Ming Hsu et al. All of the copending applications have the same assignee as the present application. The disclosures of the above identified applications are incorporated herein by reference.
