Liquid crystal display apparatus and manufacturing method...

Liquid crystal cells – elements and systems – Liquid crystal system – Liquid crystal for recording or imaging on photosensitive...

Reexamination Certificate

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C349S001000

Reexamination Certificate

active

06504581

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display apparatus of an active matrix system wherein a number of TFT (thin film transistors) are arranged together with pixel electrodes, and a manufacturing method thereof.
With respect to patterning methods for a TFT array substrate for a liquid crystal display apparatus using TFTs, two methods are mainly used:
one is a batch exposing method in which, by using a conventional large-size mask, an exposing process is applied at one time to a display area constituting the liquid crystal display apparatus and a panel peripheral portion including a wiring portion for transmitting scanning signals and data signals to the display area from external circuits or a transfer pad for applying a voltage to a counter substrate; and
the other is a divisional exposing method in which the display area and the panel peripheral portion, which are divided into a plurality of small masks, are exposed while they are repeatedly shifted on the array substrate.
The main feature of the batch exposing method is that no border line appears on the pattern on the array substrate since an electron beam or a laser beam is used so as to directly draw patterns in the pattern drawing method upon manufacturing the large-size mask; however, the disadvantages of this method are that the mask is very expensive and that the pattern is not changed easily. In contrast, the division exposing method, which uses inexpensive masks as compared with the batch exposing method and allows easy alternation of the pattern, have been widely used; however, the disadvantage of this method is that a plurality of border lines appear on the display area due to the divided masks.
As described above, in the division exposing method, since a plurality of border lines appear on the display area, fine differences in the finishing precision of patterns on both of the sides of the border lines give adverse effects on the display characteristic, with the result that the differences in luminance on the borders become conspicuous, and are visually recognized as so-called shot unevenness. Moreover, recently, as the liquid crystal display apparatuses have been improved to have high quality and high precision, variations in the aperture ratio, the occurrence of domains and dispersions in the gradation setting at the time of assembling the panel into the module due to fine process dispersions, which have conventionally not raised any problems, now raise the problem of emphasizing the shot unevenness. Here, it is well known that, although the visibility of the human eye is very high in recognizing regular pattern layouts and differences in luminance, it is relatively low in the recognition of patterns that gradually change over a wide range. Therefore, the object of the present invention is to improve the quality of the liquid crystal display apparatus by making the display unevenness less conspicuous by utilizing the vagueness of the visibility of the human eye, and to widen the margin of the process by absorbing process dispersions, without causing a reduction in the yield of processing products.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 1 of the present invention, which is used in a liquid crystal display apparatus including:
(1) a TFT array substrate having a plurality of scanning lines formed on a transparent insulating substrate by a metal film, a plurality of data lines formed on or beneath the scanning lines so as to be separated by an insulating film in such a manner as to intersect the scanning lines, switching elements that are formed by a semiconductor layer at respective intersections between the scanning lines and the data lines, and pixel electrodes that are formed by a transparent conductive film and electrically connected to the switching elements; and
(2) a counter substrate provided with a liquid crystal interposed between the TFT array substrate and the counter substrate;
wherein a divisional exposing method is adopted as a patterning method on the TFT array substrate, so that adjacent exposing areas within a display area of the liquid crystal display apparatus have overlapped portions with each other being divided into a plurality shots, and so that a shot layout is defined in such a manner that, within the overlapped exposing areas; wherein the portion which comes closer to a predetermined shot area is subjected to a greater distribution of the predetermined shot.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 2 of the present invention, which is used in a liquid crystal display apparatus including:
(1) a TFT array substrate having a plurality of scanning lines formed on a transparent insulating substrate by a metal film, a plurality of data lines formed on or beneath the scanning lines so as to be separated by an insulating film in such a manner as to intersect the scanning lines, switching elements that are formed by a semiconductor layer at respective intersections between the scanning lines and the data lines, and pixel electrodes that are formed by a transparent conductive film and electrically connected to the switching elements; and
(2) a counter substrate provided with a liquid crystal interposed between the TFT array substrate and the counter substrate;
wherein a divisional exposing method is adopted as a patterning method on the TFT array substrate, so that adjacent exposing areas within a display area of the liquid crystal display apparatus have overlapped portions with each other being divided into a plurality shots,
wherein a shot layout is defined in such manner that, within the exposing areas having quadruple overlaps; wherein the portion which comes closer to a predetermined shot area is subjected to a greater distribution of the predetermined shot.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 3 of the present invention is arranged so that, within the overlapped exposing areas, the shot is selected by using a pixel size as one unit.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 4 of the present invention is arranged so that, within the overlapped exposing areas, the shot is selected by using random numbers.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 5 of the present invention is arranged so that, within the overlapped exposing areas, the ratio occupied by a predetermined shot is selected in proportion to the distance from the border between one of the predetermined area and the other area of a different shot.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 6 of the present invention is arranged so that the overlapped exposing areas have a width greater than 4 mm.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 7 of the present invention is arranged so that, within the overlapped exposing areas, a shot adjacent to a different shot is allowed to have a multi-exposure area of 1 to 5 &mgr;m.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 8 of the present invention is applied as a patterning method to any one of steps of forming the scanning-line, forming the semiconductor-layer, forming the data-line and forming the pixel-electrode.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 9 of the present invention is applied to a plurality of steps among the steps of forming scanning-line, forming the semiconductor-layer, forming the data-line and forming the pixel-electrode, wherein the same shot layout is used within the overlapped areas among the above-mentioned applied steps.
The manufacturing method of a liquid crystal display apparatus in accordance with claim 10 of the present invention is applied to a plurality of steps among the steps of forming scanning-line, forming the semiconductor-layer, forming the data-line and forming the pixel-electrode, wherein individuall

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