Optimizing a position of injection holes of a liquid crystal display
Original Publication Date: 2000-Nov-01
Included in the Prior Art Database: 2003-Jun-18
Disclosed is liquid crystal display (LCD) design for efficient manufacturing process. In liquid crystal injection process it is important to reduce process time and not to remain bubbles at the corner of LCD cell. Inadequate vacuum of the cell or release of gas from substrate surface generates bubbles in LCD cell. In order to achieve these purposes, several techniques can be used. These are as follows, (1)injection hole size (2)injection hole number, and (3)vacuum process time. New injection hole design proposed here is effective to reduce process time and to disperse bubbles in side edge of the LCD cell. In injection process rubbing direction controls flow direction of liquid crystals. Especially in IPS(in plane switching) mode rubbing direction is parallel between two substrate. Anisotropic flow of liquid crystals is distinguished in IPS mode compared with TN mode. Therefore, optimizing the number, the position, and the sizeof the injection holes is important and effective. There are two major architectures in IPS mode, one is single domain and the other is dual domain. Single domain mode has an aslope rubbing direction. If positions of injection holes are symmetric to the cell center, asymmetrically liquid crystals flow in LCD cell (Fig1). This causes longer process time and larger corner bubble. In order to avoid this, positions of injection holes and size of these are optimized in two cases; one is 18.1 inch diagonal (aspect ratio 4:5) cell with two injection holes and the other is 20.8 inch diagonal (aspect ratio 3:4) cell with two injection holes. Fig2 shows the effect of positions of each hole on injection time. In this figure each of two holes is moved separately.