Solution for making photoconductive layer and an electrophotogra

Details Solution for making photoconductive layer and an electrophotogra Solution for making photoconductive layer and an electrophotogra

1998-07-30

2000-03-21

Rodee, Christopher D.

Radiation imagery chemistry: process, composition, or product th

Producing cathode-ray tube or element thereof

Using specified radiation-sensitive composition other than a...

430 70, 430 72, G03G 506

Patent

active

060400978

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a solution for making a photoconductive layer and a method of electrophotographically manufacturing a viewing screen for a cathode ray tube(CRT) using the solution, and more particularly to a photoconductive solution which has higher charge characteristics by a corona discharger with a similar photoconductivity to one in the prior art.


BACKGROUND OF THE INVENTION

Referring to FIG. 1, a color CRT 10 generally comprises an evacuated glass envelope consisting of a panel 12, a funnel 13 sealed to the panel 12 and a tubular neck 14 connected by the funnel 13, an electron gun 11 centrally mounted within the neck 14 and a shadow mask 16 removably mounted to a sidewall of the panel 12. A three color phosphor screen is formed on the inner surface of a display window or faceplate 18 of the panel 12.
The electron gun 11 generates three electron beams 19a or 19b, said beams being directed along convergent paths through the shadow mask 16 to the screen 20 by means of several lenses of the gun and a high positive voltage applied through an anode button 15 and being deflected by a deflection yoke 17 so as to scan over the screen 20 through apertures or slits 16a formed in the shadow mask 16.
In the color CRT 10, the phosphor screen 20, as shown in FIG. 2, comprises an array of three phosphor elements R, G and B of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements R, G and B.
A thin film of aluminum 22 overlies the screen 20 in order to provide a means for applying the uniform potential applied through the anode button 15 to the screen 20, increase the brightness of the phosphor screen and prevent from degrading ions in the phosphor screen and decreasing the potential of the phosphor screen. And also, a film of resin such as lacquer(not shown) may be applied between the aluminum thin film 22 and the phosphor screen to enhance the flatness and reflectivity of the aluminum thin film 22
In a photolithographic wet process, which is well known as a prior art process for forming the phosphor screen, a slurry of a photosensitive binder and phosphor particles is coated on the inner surface of the faceplate. It does not meet the higher resolution demands and requires a lot of complicated processing steps and a lot of manufacturing equipments, thereby necessitating a high cost in manufacturing the phosphor screen. And also, it discharges a large quantity of effluent such as waste water, phosphor elements, 6th chrome sensitizer, etc., with the use of a large quantity of clean water.
To solve or alleviate the above problems, the improved process of electrophotographically manufacturing the screen utilizing dry-powdered phosphor particles is developed. U.S. Pat. No. 4,921,767, issued to Datta at al. on May 1, 1990, describes one method of electrophotographically manufacturing the phosphor screen assembly using dry-powdered phosphor particles through the repetition of a series of steps represented in FIGS. 3A to 3E, as is briefly explained in the following(FIG. 3D and FIG. 3E respectively show a developing step and a fixing step described in our copending Korean patent application Serial No. 95-10420 filed on Apr. 29, 1995 and assigned to the assignee of the present invention.)
Prior to the electrophotographic screening process, foreign substance is clearly removed from an inner surface of a panel by several conventional methods. Then, a conductive layer 132, as shown in FIG. 3A, is formed by conventionally coating the inner surface of the viewing faceplate 18 with a suitable conductive solution comprising an electrically conductive material which provides an electrode for an overlying photoconductive layer 134. The conductive layer 132 can be an inorganic conductive material such as tin oxide or indium oxide, or their mixture or, preferably, a volatilizable organic conductive material consisting of a polyelectrolyte commerc

REFERENCES:
patent: 5405722 (1995-04-01), Data et al.
patent: 5554468 (1996-09-01), Datta et al.
Borsenberger, Paul M and David S. Weiss. Organic Photoreceptors for Imaging Systems. New York: Marcel-Dekker, Inc. pp. 416-419, 1993.

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