Method for producing color filters

#The present invention relates to a method for making color filters for use in a variety of light-receiving surfaces such as LCD devices, color video cameras, or the like. More specifically, the present invention relates to an improved method for making color filters which involves simplified manufacturing procedures, provides improved smoothness, and reduces the amount of effort required for treating solvent waste that may be produced in conjunction therewith.

#With the rapid growth of the information industry and the continuous breakthroughs in the development of display technology, a trend is now becoming increasingly recognizable that flat panel displays (FPD), which take up much smaller space, are gradually taking over the place currently occupied by the traditional cathode ray tubes (CRT). Among the various flat panel displays, liquid crystal displays (LCD), because of their light weight, small thickness, low driving voltage required, and low energy consumption, have assumed a leading position. Another reason for the wide popularity of LCDs can also be attributed, at least in part, to the rapid development of the technologies that LCDs have been associated with. More recently, with the successful development of thin film transistors (TFT), LCDs now have acquired the capability of becoming a full-color display ready for a much broader consumer market. This development further enhances the already immense potential of LCDs.

#With both the multi-color and full-color LCDs, chroma control and brightness control are the two most important elements. These elements are provided by a high-gray level (black-and-white) LCD, color filter films, and backlight devices. Of these elements, color filters provide the most important role for color control.

#The present invention will be described in detail with reference to the drawing showing the preferred embodiment of the present invention, wherein:

#FIGS. 1A through 1F are schematic diagrams showing the various stages according to a first preferred embodiment of the process disclosed in the present invention which utilizes the electrodeposition lithographic method.

#FIGS. 2A and 2B are a schematic diagrams of a single-exposure photomask and a multiple-exposure photomask, respectively, which can be utilized to produce regions of varying levels of photo exposure on the photoresist by precise movements thereof.

#The present invention discloses an improved process for making color filters for use in light receiving surfaces such as LCDs which allows simplified manufacturing procedures, provides improved smoothness, and reduces spent solvent disposal. The process disclosed in the present invention includes the steps of (1) coating a photosensitive film on an electrically conductive glass substrate, (2) subjecting the photosensitive film to a masked exposure, (3) developing an intended pattern using a developer solvent, and (4) curing the remaining portions of the photosensitive film to form a permanent insulation layer on regions of the electrically conductive glass substrate that are not intended to be electrodeposited with color resins (i.e., the conjugate region). In a preferred embodiment of the present invention, the curing step is operated in two stages: a soft-baking at a relatively low temperature and a hard-baking at a relatively higher temperature. The photosensitive permanent insulation material for use in the present invention should have good mechanical strength, high hardness, and provide good smoothness.

#The process disclosed in the present invention provides the following advantages: (1) the steps of masked exposure and solvent development are consistent with the traditional methods of making color filters, and there exist abundant mature technologies for carrying out these steps with causing environmental concerns; (2) there is no need to peel off the insulation film as required in the prior art processes; this also results in a decreased rate of rejection associated with damages caused to the color filters including the substrate as a result of such peeling off process; (3) excellent mechanical strength and hardness can be ensured with the process disclosed in the present invention because it eliminates the weak spots which may exist as a result of unwanted deposition of colored resins on the adhesive frame region; (4) the permanent insulation film of the present invention can also impart an augmented smoothness to the color filter so produced.

#In the process disclosed in the present invention, the color filters can be formed using either the electrodeposition method or the electrodeposition lithographic method. Either way, the method disclosed in the present invention is consistent with the technologies that have been developed for making color filters. Thus, excellent precision can be ensured and significant improvement obtained without incurring large expenses in personnel training or acquiring additional equipment.