Photocopying – Projection printing and copying cameras – Combined with or convertible to a contact printer
Patent
1984-01-16
1986-01-07
Grimley, Arthur T.
Photocopying
Projection printing and copying cameras
Combined with or convertible to a contact printer
118659, 118647, G03G 1510
Patent
active
045630801
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to electrophotography and more particularly is concerned with the application of liquid toner to an electrostatic image and to the processing of electrostatic images using liquid toner.
There are a number of difficulties in the satisfactory application and removal of liquid toner; disadvantages of known systems include:
(a) waste of toner which causes both unnecessary purchase of expensive toner and unnecessary labour in the dirty task of replenishing the machine with fresh toner;
(b) non-uniformity of toning over the area being processed;
(c) traps in the toner feed path in which toner may move only slowly, which may permit changes in the properties of the slow moving toner relative to that which is delivered quickly, which again causes non-uniformity in toning; and
(d) failure to remove liquid toner completely before fusing from areas which should be clear, thus leading to grey or speckled areas in the eventual image which should be white.
The present invention aims to alleviate or ameliorate these difficulties, and is especially applicable to making copies which require very fine detail, for example in producing miniature or micro-copies and especially when copying onto TEP film (transparent electrophotographic film) such as the TEP materials supplied commercially by James River Graphics of Massachussetts, United States, Kodak, and others. The invention is also applicable to any other electrophotographic process and electrophotographic equipment using liquid toner. The invention is also of particular value when up-dating is carried out, i.e., when a piece of material receives an image covering less than its whole area, that image is developed and may be viewed, and at a later time the image-carrying material is re-exposed and processed to receive an additional image. In these circumstances, it is important that the exposure and processing of the first image have a negligible effect on that part of the image-receiving material which will later receive another image, and likewise that the exposure and processing of the second image have a negligible effect on the first image.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method of applying liquid toner to a predetermined part of an electrophotographic film, which comprises:
(1) supporting the electrophotographic film at a predetermined distance from an electrode having a flat surface with a toner supply orifice therein, such that the predetermined part of the electrophotographic film is adjacent to said flat surface of the electrode; and
(2) delivering a predetermined quantity of liquid toner through said toner supply orifice so as to form a region of toner between, and in contact with, (a) the electrode and (b) the predetermined part of the electrophotographic film, the quantity of liquid toner deilvered being such that the region of toner between the electrode and the electrophotographic film is retained in position by surface tension forces.
According to a second aspect of the invention, there is provided a method of processing an electrostatic image in a predetermined part of an electrophotographic film, which comprises:
(1) supporting the electrophotographic film at a predetermined distance from an electrode having a flat surface with a toner supply orifice therein such that the predetermined part of the electrophotographic film is adjacent to said flat surface of the electrode;
(2) delivering a predetermined quantity of liquid toner through said toner supply orifice so as to form a region of liquid toner between, and in contact with, (a) the electrode and (b) the predetermined part of the electrophotographic film, the quantity of liquid toner delivered being such that toner is retained in said region between the electrode and the electrophotographic film by surface tension forces; and
(3) removing the toner from said region after effecting development of the electrostatic image.
The electrophotographic film is preferably supported at a distance in
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patent: 3802388 (1974-04-01), La Poma
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patent: 4141647 (1979-02-01), Lempke et al.
patent: 4265996 (1981-09-01), Simm et al.
Xerox Disclosure Journal, vol. 5, No. 3, May-Jun. 1980, article by P. H. Kondo entitled: "Liquid Development Apparatus", pp. 283-284.
Grimley Arthur T.
P.A. Management Consultants Limited
Warren David
LandOfFree
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