1. Technical Field
The present invention relates to a substrate for a liquid crystal device suitable for improving the image quality displayed on the liquid crystal device and a method of manufacturing the same, an electro-optic apparatus, and electronic equipment.
2. Related Art
A liquid crystal device which corresponds to an electro-optic apparatus is configured with two substrates such as a glass substrate or a quartz substrate, and liquid crystal encapsulated therebetween. There is the liquid crystal device employing an active system having non-linear elements such as TFTs (Thin Film Transistor) or TFDs (Thin Film Diode) provided on the pixel-to-pixel basis, and signal electrodes and pixel electrodes are electrically connected via the non-linear elements.
The liquid crystal device of an active system includes the non-linear elements arranged in a matrix pattern on one substrate and opposed electrodes arranged on the other substrate to enable display of images by changing the optical characteristics of the liquid crystal layer encapsulated between the substrates according to the image signals.
The TFT substrate having the TFTs arranged thereon and the opposed substrate arranged so as to oppose the TFT substrate are manufactured separately. These substrates are bonded to each other with high degree of accuracy in a panel assembly process, and then the liquid crystal is encapsulated therebetween.
In the panel assembly process, alignment films are formed on the opposed surfaces of the TFT substrate and the opposed substrate which are manufactured separately in the respective substrate manufacturing process, that is, on the surfaces of the opposed substrate and the TFT substrate which come in contact with the liquid crystal layer, and then a rubbing process is carried out. Then, a sealing member which corresponds to an adhesive agent is formed on peripheral sides on one of the substrates. The TFT substrate and the opposed substrate are bonded using the sealing member and are press-cured while being adjusted in alignment. The sealing member is formed with a notch, which is used for filling the liquid crystal.
When the alignment film is formed and applied with the rubbing process, the alignment of liquid crystal molecules when no voltage is applied is determined. The alignment film is formed by applying, for example, polyimide by a thickness of approximately several tens nanometers. By forming the alignment films on the surfaces of both the substrates opposing the liquid crystal layer, the liquid crystal molecules are aligned along the surfaces of the substrates. The rubbing process is a process to be applied to an alignment-anisotropic film by forming fine grooves on the surface of the alignment film, and the alignment of the liquid crystal molecules is defined by carrying out the rubbing process on the alignment film in a certain direction.
In consideration of productivity, an array manufacture in which film formation and a photolithography process are repeated on one piece of mother glass substrate without cutting the same to form elements for a plurality of TFT substrates on the mother glass substrate at once may be employed.
In the rubbing process, a rotating rubbing roller is slid on the surface of the substrate. Foreign substances generated by the rubbing process like chips of the alignment film move with the movement of the rubbing roller and are swept out of the substrate. However, since there generates a level difference at every element in the array manufacture, the chips generated during the rubbing process may remain on the adjacent elements due to the level difference.
Therefore, in JP-A-2004-240053, a technology to prevent entry of the chips generated during the rubbing process into the display area by forming projections in the peripheral area on the TFT array substrate is disclosed.
However, in JP-A-2004-240053, there is no disclosure relating to the opposed substrate manufactured by the array manufacture, and the chips generated during the rubbing process remain on the opposed substrate even with the technology disclosed in JP-A-2004-240053. When the chips enter the effective display area, there arises a problem such that the alignment of the liquid crystal molecules is disordered and hence the image quality is deteriorated at a portion where the chips are attached.
USPTO Backgrounds
USPTO Backgrounds