Liquid crystals display (LCD) have become important in recent years with applications including monitors in notebook personal computers, screens of TV-game, screens of portable television sets, viewfinders of video-recorders, etc. Materials that are used indirectly in LCD and VLSI manufacturing include photoresist, chemicals, solvents, etc., and components such as drivers and passive devices. The other major materials used in the manufacturing of LCD are glass substrates, polarizers, ITO films, surface alignment material, spacers, and the liquid crystal material. The photolithographic system in LCD manufacturing is as in semiconductor and compact disc (CD) manufacturing. This depends on the clean room operation of clean room maintaining the process and transport areas as a micro-environment enclosure under Class 10 conditions. The procedure of spacers spraying and sealing in the LCD plate is however very different from the other procedures. The spacers are used to reserve a gap in two substrates (Fig.1). The series of LCD modules covers each of the procedures: baking, curing, rubbing, dry cleaning, combination rubbing and dry cleaning, spacer spraying (Fig.2), gasket seal printing and dispensing, combination alignment, assembly, and liquid crystal filling. The quantity and distribution of the spacers determines the quality of the liquid crystals display product[1]. The biggest obstacle for the profitability for large-area LCD manufacturing is the high rate of product defects. This is because of the fact that if only a few out of a million circuits on a large-area panel are defective, it causes the entire panel to be defective. Many engineers worked on solving the production inspection problems for high-quality and large-area LCD produced with acceptable levels of product defects. The automatic demand of the spacers counting device then becomes increasingly intensive.

Fig.2 the spacer spraying of a LCD plate

In this paper the on-line spacers counting device consists of the following:

* Three microscope, CCDs and a frame grabber.

* A conveyer, that is able to transport a LCD plate.

* A software for nine inspection points of spacer counting and analysis(Fig.3).

Fig.3 the on-line spacers counting device

In conjunction with the aforesaid equipment we use a discriminate functions processing technique and a counting mask recognition (detection) algorithm to analyze the spacers on a LCD plate.

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