1. Technical Field
The present invention relates to liquid crystal displays (LCDs), and more particularly, to an LCD substrate structure and fabrication method.
2. Related Art
As modern societies are changing into information societies, LCDs are emerging as an important replacement display technology for cathode ray tube (CRT) technology. While a CRT has performance and price benefits, the CRT also has significant drawbacks with regard to miniaturization and mobility. On the other hand, the LCD module provides size, weight, and power consumption advantages over the CRT.
An LCD panel includes an array substrate, a color filter substrate coupled with the array substrate and liquid crystal interposed between the array and color filter substrates. The array substrate may include an array of thin film transistors. The color filter substrate may include red (R), green (G), and blue (B) (RGB) color filter layers.
LCD panels may be fabricated by forming multiple separate transistor arrays on a first substrate, and by forming multiple corresponding color filter areas on a second glass substrate. The glass substrates are coupled together. The glass substrates are then cut into individual LCD panels.
When the pair of glass substrates are cut into the LCD panels, the glass substrates are cut in a first direction to form bar-shaped liquid crystal cells spanning multiple LCD panels. Then, liquid crystals are injected between upper and lower substrates of each bar-shaped liquid crystal cell. The cells are sealed to prevent leakage of the liquid crystals. After sealing, the bar-shaped liquid crystal cells are inspected and tested, and cut in a second direction perpendicular to the first direction to form separate individual LCD panels.
A scribing process cuts the cells into individual LCD panels. The edges of the LCD panels are then ground. The grinding process removes shorting bars provided in the liquid crystal cell that prevent static electricity discharges. The grinding process also removes portions of signal lines that were used for inspection and testing of the LCD panels while in the form of the bar-shaped liquid crystal cells.
FIG. 1 shows a portion of a cell 10. The first scribe line shows the direction that the substrates are cut to form the cell 10. The second scribe line shows the direction that the cell 10 is cut to separate the cell into individual LCD panels. The transistor array for a given LCD is shown by the active area 12a. The inactive area outside of the active area is labeled 12b. 
The active area 12a of each LCD in the cell 10 may be tested prior to separating the cell into individual panels. During testing, drive signals and RGB data signals are applied via signal lines 15 and inspection pads 11. The signal lines 15 and inspection pads 11 are formed in the inactive area 12b. 
The signal lines 15 are electrically connected with data pads, gate pads, and control pads. Alternatively, some LCD cells may provide a connection terminal 18 through which test data and control signals may be applied. Through the signal lines 15, test data signals and gate signals are applied to the thin film transistors in the active area 12a. The test data signals and gate signals activate or deactivate pixels in the LCD to determine whether any pixels are defective.
FIG. 2 is an enlarged view of the area A shown in FIG. 1. FIG. 2 shows the grinding region 202 that is removed in the grinding process. FIG. 2 also shows that the inspection pads include multiple individual test pads 11a. The test pads 11a are electrically connected with the signal lines 15. The test pads 11a may provide an injection point for pixel data signals, transistor gate signals, control signals, or other types of test signals.
If the active area 12a passes inspection, grinding is performed to break the signal lines 15. As noted above, the signal lines provide the test signals for the active area 12a. The signal lines 15 are not necessary for normal operation of the LCD panel.
A portion 204 of each of each signal line 15 is formed adjacent to the first scribe line and inside the grinding region 202. The grinding process breaks the portions 204 of the signal lines 15 inside the grinding region 202. The LCD panels are complete after grinding and after scribing along the second scribe line.
Prior processes for producing LCD panels performed a large number of process steps. The process steps included scribing to form the cells, scribing to form the individual panels, and grinding. As the number of process steps increases, yield and throughput may drop. The large number of process steps is particularly disadvantageous in fabricating smaller LCD panels because many smaller panels may need to be cut and ground when starting with large substrates.
USPTO Backgrounds
USPTO Backgrounds