Patent Application
20080090028
Refer to
The backlight module 210 includes a reflection mask 212, a light source 214 and a light guide 216. The light emitted from the light source 214 (such as cold cathode fluorescent lamp) is reflected by the reflection mask 212 and directed by the light guide 216 to be projected outwards to the LCD panel 230. In this embodiment the backlight module 210 is a direct type backlight module. It also may be sideward incident type or other types.
The LCD panel 230 adopts In-Plane Switching (generally called IPS) or other desired types such as multi-vertical alignment (generally called MVA) type.
Referring to
Referring to
The optical film made from polymethyl methacrylate previously discussed includes a material selected from either of PMMA, PMMA with a replaced functional group and PMMA mixing groups, and a solvent. The material of PMMA, PMMA with a replaced functional group or PMMA mixing groups is blended evenly at a desired ratio in the solvent according to required characteristics of the optical film of polymethyl methacrylate, preferably at the amount between 20% and 40% by weight.
The functional group of PMMA to be replaced set forth above is methyl. The methyl may be selectively replaced by other functional groups such as ethyl, propyl, isopropyl, n-butyl, isobutyl, neo-butyl, n-hexyl, isohexyl, cyclohexyl or the like. The PMMA mixing groups include at least a kind of polymer, small molecular, plasticizer, UV absorbent, antidegradant or nano scale particles. The solvent includes at least aromatics, cycloalkanes, ethers, esters, ketones or mixing materials thereof. The aromatics is selected from either of methyl benzene, O-Xylene, M-Xylene and P-Xylene. The cycloalkanes include cyclohexane. The ethers is selected from either of Diethyl ether and Tetrahydrofuran (THF). The esters is selected from either of methyl acetate and ethyl acetate. The ketone group is selected from either of acetone, methylethylketone (MEK) and 1-methylpyrrolidone (NMP). The solvents set forth above serve only as an embodiment and are not the limitation of the invention.
The nano scale particles have diameters smaller or equal to 100 nanometers, preferably smaller than 80 or 50 nanometers. Moreover, the optical film of polymethyl methacrylate may further include silica at the amount of 0.5% to 15% by weight.
The optical film of polymethyl methacrylate may further include multiple particles formed by either of PMMA, PMMA with a replaced functional group or PMMA mixing groups covered by an elastic rubber material. The elastic rubber material may be selected from the family consisting of butyl acrylate, polymethyl methacrylate and styrene. The elastic rubber articles are formed at a size smaller than 10 micrometers or even at nanometer scale. The adding amount of the particles is 2.5% to 50% by weight. By adding the elastic rubber particles the mechanical characteristics of the optical film can be improved, including enhancing the extensibility and the like.
The second optical film 226 has been tested with optical characteristics shown in Table 1 listed below:
The light transmission of the second optical film 226 was measured through a Spectrophotometer (such as HITACHI U-4100 Spectrophotometer). During measuring process the second optical film 226 at a size of 4×4 cm2 is disposed at a measuring position and scanned by a light of wavelength in the range of 380-700 nm. The light transmission of the second optical film 226 shown in Table 1 is obtained at the wavelength of 550 nm.
The Haze of the second optical film 226 is measured through a Haze meter (such as NDH 2000 Haze meter). During the measuring process a calibration testis done first, then the second optical film 226 at the size of 4×4 cm2is disposed at the measuring position to get the haze value.
The thickness of the second optical film 226 is measured through an optical thickness meter of model No. ETA-STC. During measuring process the second optical film 226 is positioned and the refraction index of the second optical film 226 is entered. Through optical reflection principle the thickness of the second optical film 226 can be obtained. The refraction index of the second optical film 226 can be measured through an ABBE Refractometer. For instance using a filter of wavelength 589 nm, the thickness of the second optical film 226 under the wavelength of 589 nm can be obtained.
Then the Re and Rh values of the second optical film 226 can be measured through an Optical birefringence analyzer such as model No. KOBRA-21ADH. The second optical film 226 of 4×4 cm2 is placed on the measuring position; input the thickness and measuring angular range (−50˜50) of the second optical film 226; the Optical birefringence analyzer measures the second optical film 226 at an interval of 10 in different angles; after the measurement is finished, enter the refraction index of the second optical film 226, and the Re and Rh values of the second optical film 226 can be obtained.
The measurement facilities and processes previously discussed are only examples. To those skilled in the art other suitable measurement facilities may be selected and the measurement processes can be altered to measure various optical characteristics of the second optical film 226.
Compared the embodiment of the LCD of the invention with the conventional one (referring to
The third optical film 262 previously discussed mainly is made from Triacetyl-cellulose. But it also can be formed by the same composition as the second optical film 226 does. Refer to
Compared another embodiment of LCD of the invention with the conventional one (referring to
The first polarizer 220 and second polarizer 260′ previously discussed have the optical film of polymethyl methacrylate disposed only on one side of the polarizing layers (namely the first polarizing layer 224 and the second polarizing layer 264), namely the second optical film 226 and the third optical film 262′. However, the first optical film 222 or the fourth optical film 266 may also be made by the same composition as the second optical film 226 and the third optical film 262′ do. In the embodiment and another embodiment set forth above, the first polarizing layer 224 and the second polarizing layer 262 are mainly made from polyvinyl alcohol. Of course, other types of polarizing material may also be used.
In addition, in the embodiments set forth above, Triacetyl-cellulose is used as the main material to make the optical films (such as the first optical film 222 or fourth optical film 266). It may be replaced by other suitable materials as polycarbonate or cyclic olefin polymer.
Moreover, as polymethyl methacrylate has a smaller water absorption capability and moisture permeability than Triacetyl-cellulose, the second optical film 226 and the third optical film 262′ have more desirable water absorption capability and moisture permeability than the conventional TAC film. Hence when the second optical film 226 and the third optical film 262′ are used in high temperature and humidity conditions, they are less likely to deform or generate stress due to external environments. Thus the optical characteristics are less likely to be affected.
Furthermore, as the second optical film 226 and third optical film 262′ are made from polymethyl methacrylate which is a polymer, they have improved mechanical characteristics such as greater toughness and the like.
In short, the LCD of the invention mainly includes one optical films made of polymethyl methacrylate. Its has improved display quality than the conventional LCDs. Moreover, the optical films of the invention have smaller water absorption characteristics and moisture permeability than TAC film, and enhanced toughness. Hence the optical films are less likely to deform or generate stress due to external environments, and optical characteristics also are less likely to be affected. The life span of the LCD of the invention also is longer than the conventional ones.
While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 095138070 | Oct 2006 | TW | national |
