Patent Application
20070263146
Referring to
A first optical compensation film 214, a first retardation film 213, and a first polarizer 212 are disposed in that order on an outer surface of the first substrate 22. A second optical compensation film 224, a second retardation film 223, and a second polarizer 222 are disposed in that order on an outer surface of the second substrate 22. The first and second retardation films 213, 223 may be wide-band quarter-wave plates, which are biaxial retardation films.
A color filter 215, a transparent common electrode 216, and a first alignment film 218 are disposed in that order on an inner surface of the first substrate 21. The common electrode 216 is made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO).
A passivation layer 229 is formed on an inner surface of the second substrate 22. The passivation layer 229 forms a plurality of separate protrusions (not labeled). A plurality of separate transmission electrodes 226 is formed on the inner surface of the second substrate 22. The protrusions of the passivation layer 229 and the transmission electrodes 226 are alternately disposed on the inner surface of the second substrate 22. A plurality of reflection electrodes 227 is formed on inner surfaces of the protrusions of the passivation layer 229. A second alignment film 228 covers the reflection electrodes 227 and the transmission electrodes 226. In accordance with an exemplary embodiment of the present invention, the transmission electrodes 226 are made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), and the reflection electrodes 227 are made of metal with a high reflective ratio such as aluminum (Al).
The liquid crystal layer 23, the common electrode 216, the transmission electrodes 226, and the reflection electrodes 227 cooperatively define a plurality of pixel regions (not labeled). Each pixel region includes a reflection region corresponding to a respective reflection electrode 227, and a transmission region corresponding to a respective transmission electrode 226. A thickness of the liquid crystal layer 23 in the transmission regions is greater than that of the liquid crystal layer 23 in the reflection regions.
The first polarizer 212 has an absorption axis parallel to a rubbing direction of the first alignment film 218, and the second polarizer 222 has an absorption axis perpendicular to that of the first polarizer 212. A slow axis of the first retardation film 213 maintains an angle of 45° relative to the absorption axis of the first polarizer 212. A slow axis of the second retardation film 223 maintains an angle perpendicular to the slow axis of the first retardation film 213.
The first and second alignment films 218, 228 are each homogeneously aligned alignment films. The alignments of the first and second alignment films 218, 228 are parallel to each other. A pre-tilt angle of the liquid crystal molecules adjacent to the substrates 21 and 22 is in a range from 0° to 15°. The liquid crystal molecules may be positive uniaxial liquid crystal material that is intermingled with chiral dopant. Typically, a ratio d/p=0˜1, wherein d represents a thickness of the liquid crystal layer 23 in the transmission regions, and p represents a pitch of the chiral dopant. The chiral dopant helps the liquid crystal molecules to orient in a twist pattern relative to a plane parallel to the first and second substrates 21, 22. Thereby, from the first alignment film 218 to the second alignment film 228, the liquid crystal molecules are oriented such that they progressively twist through an angle of 180°. Thus, the liquid crystal molecules are in a so-called twist π cell state.
Also referring to
With the above-described configuration, the LCD device 2 is capable of providing a display both in a reflection mode and a transmission mode.
During the transition process of converting the liquid crystal molecules from the twist π cell state into the bend alignment state, the liquid crystal molecules in the twist π cell state can rapidly twist when a voltage is applied thereto. That is, for the transition process, the liquid crystal molecules in the initial twist π cell state have a fast response time. Moreover, the liquid crystal molecules in the LCD device 2 are bend-aligned to have a pre-tilt angle. This helps ensure the liquid crystal molecules can more easily adjust their orientations when a voltage is applied to the LCD device 2 and a change in a driving electric field is effected. Thereby, the LCD device 2 has a fast response time.
Various modifications and alterations of the above-described embodiments are possible. For example, a thickness of the liquid crystal layer 23 in the transmission regions may be equal to that of the liquid crystal layer 23 in the reflection regions. Each of the retardation films 213, 223 may selectively instead be a single compensation film, an A-plate compensation film, or a discotic molecular film. The LCD device 2 may employ only a single optical compensation film 214/224 disposed on either the first substrate 21 or on the second substrate 22. Furthermore, any one, more, or all of the retardation films 213, 223 and/or the optical compensation films 214, 224 may be selectively disposed on or at the inner surface of either or both of the first and second substrates 21, 22.
An absorption axis of the first polarizer 312 maintains an angle in the range from 10° to 20° relative to a slow axis of the third retardation film 311, and an absorption axis of the second polarizer 322 maintains an angle in the range from 10° to 20° relative to a slow axis of the fourth retardation film 321. The slow axis of the third retardation film 311 maintains an angle in the range from 55° to 65° relative to a slow axis of the first retardation film 313, and the slow axis of the fourth retardation film 321 maintains an angle in the range from 55° to 65° relative to a slow axis of the second retardation film 323.
It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 95116846 | May 2006 | TW | national |
