Electrophotography – Control of electrophotography process – Control of developing
Reexamination Certificate
1999-07-09
2001-05-01
Grainger, Quana M. (Department: 2852)
Electrophotography
Control of electrophotography process
Control of developing
C399S055000
Reexamination Certificate
active
06226468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of testing a liquid developer, a liquid developer selected based on the testing method, and an image forming method and an apparatus, such as a photocopier, a facsimile machine, a printer, and the like using the selected liquid developer. The liquid developer includes improved characteristics, such as a decreased background soiling and an increased image density.
2. Discussion of the Background
As one electrophotographic image forming method, a liquid developing method is known, in which liquid developer is supplied to a narrow gap between a photoconductive member (electrostatic latent image bearer) and a liquid developer bearer, such as a developing roller or a developing belt. Thereby, solid toner particles in the liquid developer move toward and adhere onto a latent image carried on the photoconductive member to form a toner image. Such a developing method is referred to as “a narrow gap developing method.” In general, an electrophotographic liquid image forming method providing a narrow gap developing method achieves a quality sharp image.
Japanese Laid-open Patent Publication No. 99157/1975 describes an electrophotographic liquid image forming method in which a dielectric release liquid is first applied to a latent electrostatic image on a charge-carrying surface. The latent electrostatic image is then developed with a dielectric cohesive ink by a developing roller or a developing belt coated with the same or a different dielectric release liquid. The developing roller and the developing belt are arranged apart from the charge-carrying surface by a narrow gap.
Japanese Laid-open Patent Publication No. 209922/1995 describes a liquid image forming method using a narrow gap developing method. A pre-wetting liquid is first applied to an electrostatic latent image on a photoconductive member. The latent image is developed with a liquid developer by a developing belt, which is arranged apart from the photoconductive member by a narrow gap.
The above dielectric release and pre-wetting, liquid methods make toner particles in the liquid developer not adhere to a non-image portion of the latent image on the charge carrying surface or the photoconductive member surface, and thereby background soiling on a recording medium is decreased. In addition, a replenishment and application mechanism for the liquid is required to supply the dielectric release or pre-wetting liquid. Accordingly, the production cost is increased for an image forming apparatus using such a dielectric release liquid or pre-wetting liquid. Further, the operating cost of the image forming, apparatus is increased due to the dielectric release liquid or pre-wetting, liquid.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to solve the above-discussed and other problems.
Another object of the present invention is to provide a novel method of testing a liquid developer for characteristics, such as a decreased background soiling and an increased image density.
Yet another object of the present invention is to provide a novel liquid developer, and an image forming apparatus and method using the developer, that forms an improved image with a decreased background soiling and an increased image density without applying a dielectric release liquid or pre-wetting liquid.
These and other objects of the present invention may be achieved by providing a novel liquid developer testing method that adjusts a narrow gap formed between circumferences of two moving elements, applies the different electric potentials to surfaces of the two moving elements to generate an electric field at the narrow gap, and applies the liquid developer to at least one of the two moving elements at a position upstream to the narrow gap in a moving direction of the moving elements. The method also includes measuring one of a thickness, a weight per unit area, and a volume per unit area of liquid developer adhered to the circumferences of the moving elements in a moving direction of the moving elements, and calculating a ratio of the thicknesses, weights, or volumes of the liquid developer between the two moving elements according to the measuring result in the measuring step.
REFERENCES:
patent: 5028964 (1991-07-01), Landa et al.
patent: 5652080 (1997-07-01), Yoshino et al.
patent: 5666616 (1997-09-01), Yoshino et al.
patent: 5953559 (1999-09-01), Obu
patent: 6029036 (2000-02-01), Itaya et al.
patent: 50-99157 (1975-08-01), None
patent: 7-209922 (1995-08-01), None
Obu Makoto
Tsukamoto Takeo
Grainger Quana M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
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