Radiation imagery chemistry: process – composition – or product th – Producing cathode-ray tube or element thereof
Reexamination Certificate
2000-02-16
2001-02-13
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Producing cathode-ray tube or element thereof
C427S469000, C427S071000
Reexamination Certificate
active
06187487
ABSTRACT:
The invention relates to a method of developing a latent charge image on a photoreceptor which is disposed on an interior surface of a faceplate of a cathode-ray tube (CRT), and, more particularly, to a method of operating a tank grid to control the electrostatic forces within a developing apparatus.
BACKGROUND OF THE INVENTION
An apparatus for developing a latent charge image on a photoreceptor that is disposed on an interior surface of a viewing faceplate of a display device, such as a cathode-ray tube (CRT), using triboelectrically charged particles, is described in U.S. Pat. No. 5,477,285, issued on Dec. 19, 1995, to G. H. N. Riddle et al. In a first embodiment of the developing apparatus, a developing chamber having insulating sidewalls and an insulative panel support is described. A triboelectric gun for directing charged screen structure material onto a photoreceptor provided on the interior surface of the CRT faceplate panel is disposed within the developing chamber. A drawback of the developing chamber is that the electrostatically charged screen structure material creates a charge buildup on the insulating sidewalls. The electrostatic forces from the sidewalls are not well controlled and the forces vary as the charge varies. For example, when the developing chamber is cleaned, to remove excess screen structure materials from the sidewalls, the electrostatic charge decreases. The electrostatic forces also vary when the humidity changes. Variations of 500 to 5000 volts have been recorded in the measured electrostatic fields of an operating developing chamber. In another embodiment of a developing chamber described in the above-referenced U.S. Pat. No. 5,477,285, an interior chamber of conductive material, comprising a sidewall and a bottom, is disposed within the developing chamber. The conductive interior chamber is electrically floating and attracts excess screen structure material out of the powder cloud generated within the chamber by the triboelectric gun, thereby preventing both a buildup of space charge within the chamber and a high electrostatic potential on the chamber wall. However, it has been determined that the screen structure material builds up on the conductive sidewall of the inner chamber in the form of “snow banks” of agglomerated particles, which may give rise to large agglomerated particles on the screen if the particles become dislodged from the sidewall. Thus, it is desirable that the drawbacks of the prior developing apparatus be addressed and eliminated.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method is disclosed for developing an electrostatic latent charge image which is formed on a photoreceptor that is disposed on an interior surface of a faceplate panel of a CRT. The method utilizes a developer tank having a sidewall closed at one end by a bottom portion and at the other end by a panel support having an opening therethrough to provide access to the panel. A panel grid is disposed in proximity to the interior surface of the faceplate panel and operated at a first potential to control the electric field from the latent charge image. A tank grid is disposed within the developer tank and spaced from the sidewall, the bottom and the panel grid. A triboelectric gun assembly is disposed within the developer tank for imparting a desired charge polarity to the screen structure material and for distributing the charged screen structure material onto the latent charge image. Means for monitoring the deposition of the charged screen structure material onto the latent charge image and means for terminating the deposition of the charged screen structure material are provided. The novelty resides in operating the tank grid at a potential different from the potential on the panel grid so that the tank grid controls the electrostatic forces within the developer tank.
REFERENCES:
patent: 3558310 (1971-01-01), Mayaud
patent: 4921767 (1990-05-01), Datta et al.
patent: 5093217 (1992-03-01), Datta et al.
patent: 5151337 (1992-09-01), Wetzel et al.
patent: 5370952 (1994-12-01), Datta et al.
patent: 5477285 (1995-12-01), Riddle et al.
patent: 5519217 (1996-05-01), Wilbur, Jr. et al.
patent: 5637357 (1997-06-01), Stachelhaus et al.
patent: 5790913 (1998-08-01), Roberts, Jr. et al.
patent: 6007952 (1999-12-01), Ciampa et al.
patent: 647595 (1995-04-01), None
Collins Brian Thomas
Matey James Regis
Poliniak Eugene Samuel
Ritt Peter Michael
Irlbeck Dennis H.
McPherson John A.
Tripoli Joseph S.
LandOfFree
Method of developing a latent charge image does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of developing a latent charge image, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of developing a latent charge image will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2611821