This application claims priority to Taiwan Application Serial Number 103114711, filed Apr. 23, 2014, which is herein incorporated by reference.
1. Field of Invention
The present invention relates to a liquid crystal display panel.
2. Description of Related Art
In recent years, the liquid crystal display panel market has been promoted due to emergence of new photovoltaic technologies and the arrival of the digital era. Liquid crystal display panels have advantages such as high resolution, relatively small-size, low driving voltages, and low energy consumption, thus are widely applied in consumer communications or found in other electronic products such as personal digital assistants (PDAs), cell phones, cameras, notebooks, desktop displays, car displays, TVs, and so on.
In general, rubbing layers can be included in the liquid crystal display panel to align the liquid crystal molecules in the panel along specific directions. The rubbing layers can align the liquid crystal molecules which are electrically undriven. The liquid crystal molecules can lie in the grooves of the rubbing layers, thus they can be arranged along the same direction. However, the rubbing layers may be polluted or there may be a leak of anchoring force depending on the manufacturing process, and many in the industry are striving to improve the problems mentioned above.
An aspect of the present invention is to provide a method for manufacturing a liquid crystal display panel including respectively forming two polymer layers on a first substrate and a second substrate. The two polymer layers are rubbed. A plurality of liquid crystal molecules and a plurality of monomers are provided between the first substrate and the second substrate. The polymer layers are disposed facing the liquid crystal molecules and the monomers. The monomers are polymerized to form two polymer rubbing layers with the polymer layers.
In one or more embodiments, the method further includes controlling a mean surface roughness of the polymer rubbing layers to satisfy:
22.33 nm≦Rms≦48.55 nm, where Rms is the mean surface roughness of the polymer rubbing layers.
Another aspect of the present invention is to provide a liquid crystal display panel including a first substrate, a second substrate, a liquid crystal layer, and two polymer rubbing layers. The second substrate is disposed opposite to the first substrate. The liquid crystal layer is disposed between the first substrate and the second substrate. The liquid crystal layer includes a plurality of liquid crystal molecules. Each of the liquid crystal molecules has a pretilt angle satisfying: 1°≦θ≦2°, where θ is the pretilt angle. The polymer rubbing layers are respectively disposed between the first substrate and the liquid crystal layer, and between the second substrate and the liquid crystal layer. A mean surface roughness of surfaces of the two polymer rubbing layer facing the liquid crystal layer satisfies:
22.33 nm≦Rms≦48.55 nm, where Rms is the mean surface roughness of the surfaces of the polymer rubbing layers.
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Reference is made to
Moreover, in this embodiment, since the roller 900 rubs each of the polymer layers 410 and 510 twice, it may increase the amount of dust or the fibers 910 dropping on the polymer layers 410 and 510 from the roller 900. One method of improvement is to reduce the pressure of the roller 900 pressing on the polymer layers 410 and 510. For example, the contact area between the roller 900 and each of the polymer layers 410 and 510 is reduced during the rubbing process, where the contact area is proportional to the pressure. Since the roller 900 is cylindrical, the contact area is proportional to a contact width NIP marked in
Moreover, both of the polymer layers 410 and 510 have rubbing grooves (such as rubbing grooves 412 in
In this embodiment, the monomers 420 can be photopolymerizable materials. That is, the monomers 420 can be polymerized to be polymers after being illuminated.
During the manufacturing process of
In one or more embodiments, a mean surface roughness Rms of the polymer rubbing layers 400 and 500 can be controlled to satisfy:
22.33 nm≦Rms≦48.55 nm, where the controlling method can be adjusting the polymerizing time of the monomers 420 (see
In greater detail, the mean surface roughness Rms of the polymer rubbing layers 400 and 500 is proportional to the amounts of the polymers 430 and 530. That is, the mean surface roughness Rms increases as the amounts of the polymers 430 and 530 increase, and the rubbing property is better. In an example, the measured anchoring force of the polymer rubbing layers 400 and 500 were 10.48×10−3 J/m2 when the contact width NIP of
In another example, the measured anchoring force of the polymer rubbing layers 400 and 500 were 18.7×10−3 J/m2 when the contact width NIP was 8 mm and the mean surface roughness Rms was 44.55 nm. The driving voltage of liquid crystal molecules in this example was about 1 volt higher than that of the liquid crystal display panel pressed with 14 mm contact width NIP and without monomers 420. In greater detail, the anchoring force increases as the mean surface roughness Rms increases, resulting in an increase of the driving voltage of the liquid crystal molecules 310, where the driving voltage herein is a voltage that turns the liquid crystal layer 300 from a dark state to a white state. However, as mentioned above, merely about 1 volt increase of the driving voltage, the liquid crystal display panel in this example had similar optical performance as the liquid crystal display panel without the polymers 420. For example, the transmittance of the liquid crystal layer 300 in this example was about 100% at the white state, which proved the switch between the white/dark states of the liquid crystal layer 300 was not severely affected when the mean surface roughness Rms≦48.55 nm.
Reference is made to
22.33 nm≦Rms≦48.55 nm.
In this embodiment, the polymer rubbing layer 400 (500) includes the polymer layer 410 (510) and a plurality of the polymers 430 (530). The polymers 430 (530) are distributed on the surface of the polymer layer 410 (510) facing the liquid crystal layer 300 to provide extra anchoring force to the liquid crystal molecules 310 of the liquid crystal layer 300.
The pretilt angle θ of the liquid crystal molecules 310 satisfies 1°≦θ≦2° if the polymer rubbing layers 400 and 500 are rubbed. This pretilt angle θ can be applied to the liquid crystal display panels using a fringe field switching (FFS) technique. The following examples provide details about the polymers 430 and 530 affecting the pretilt angle θ of the liquid crystal molecules 310. Reference is made to Table 1. The contact width NIP (see
In summary, a roller is used to rub the polymer layers of the liquid crystal display panel of the present embodiment back and forth to improve the uniformity of rubbing performance. Reduced pressures of the roller pressing on the polymer layer reduce the amounts the dust and the fibers dropping on the polymer layers. The weak anchoring force due to the reduced pressure can be compensated for by the anchoring force provided by the polymers. In addition, the polymer rubbing layers do not severely affect the pretilt angles of the liquid crystal molecules. In other words, the liquid crystal display panel of the present embodiment has a high rubbing uniformity, low pollution of unwanted fibers upon the rubbing layers, and has a high anchoring force.
Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.
Number | Date | Country | Kind |
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103114711 | Apr 2014 | TW | national |