Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Patent
1998-04-27
2000-12-12
Lee, Susan S. Y.
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
347149, B41J 2385, B41J 2395, G01D 1506, G03G 1501
Patent
active
061605646
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a single-path color electrostatic recorder for forming an electrostatic latent image on a record face of a recording medium such as paper, film or cloth concerning primary colors, by using an electrostatic recording head and developing the medium with liquid toner. More particularly, the invention relates to a color electrostatic recorder with a back rest mechanism for bringing a record medium into sliding contact with an electrostatic recording head under moderate pressure.
BACKGROUND OF THE INVENTION
By forming an electrostatic latent image on a recording medium such as paper, film or cloth with the aid of an electrostatic recording head and thereafter developing the medium with liquid toner, the electrostatic recorder records the image. On a record face of the recording medium, a spacer including silica particles on the order of several .mu.m in diameter is scattered. By pressing the recording medium against the electrostatic head from the opposite side with a pad roller and bringing the record face into sliding contact with the head surface under a moderate pressure, a discharge gap due to the spacer takes place at an appropriate space between the electrostatic head and the dielectric layer in the recording medium. In this state, occurrence of a discharge between electrodes corresponding to individual images of the electrostatic recording head leads to a charging of the recording medium in accordance with an item of image information, so that an electrostatic image is formed. Onto the recording medium having passed the electrostatic head, liquid toner in which toner particles are distributed is applied with a toner roller. When the liquid toner is applied onto the recording medium, toner particles charged in the opposite polarity to the electrostatic latent image are attracted to the electrostatic latent image formed on the recording medium by the electrostatic power and combined with the surface layer of the recording medium, so that the electrostatic latent image is developed.
With a single-path color electrostatic recorder, the above-mentioned electrostatic recording heads are generally provided respectively for four primary colors, cyan, magenta, yellow and black. The above-mentioned four colors are recorded only by one-time carrying, so that a color image is obtained.
As clear from the above, the formation of an electrostatic latent image with an electrostatic recording head must be precisely carried out to accomplish an appropriate image recording in the electrostatic recorder. Accordingly, it becomes important to bring the recording medium into sliding contact with the electrostatic recording head under appropriate pressure. An insufficient pressure would lead to a dropout phenomenon wherein the image to be recorded is interrupted halfway; on the other hand, an excessive press would lead to a spurious writing phenomenon that an image comes to be recorded in a portion not to be printed by nature.
With a general electrostatic recorder, a pad roller is provided at an opposed position to the surface of an electrostatic recording head, and the record face of the recording medium is pressed against the surface of the electrostatic recording head by using the pad roller with the recording medium interposed between it and the electrostatic recording head. When the recording medium is carried during the recording, the pad roller rolls and the recording medium is always kept in sliding contact with the surface of the electrostatic recording head under a constant pressure. An apparatus for pressing the recording medium against the electrostatic recording head by using an elastic member with the recording medium interposed between it and the opposed electrostatic recording head as described above is generally called a backrest. The backrest includes an apparatus for butting a semicylindrical pad alone against the surface in addition to one using a pad roller.
FIGS. 4A and 4B are sectional views showing the outline of a backrest using a pad roller 1
REFERENCES:
patent: 5063398 (1991-11-01), Murai et al.
patent: 5745142 (1998-04-01), Liston
Patent Abstracts of Japan, vol. 009, No. 009 (P-327), 1985 & JP 59 155871 A (Canon KK), 1984.
Patent Abstracts of Japan, vol. 018, No. 557 (P-1817), 1994 & JP 06 202430 A (Canon Inc), 1994.
Patent Abstracts of Japan, vol. 014, No. 428 (M-1025), 1990 & JP 02 169262 A (Canon Inc), 1990.
Kawatsu Toshitatsu
Komatsu Fumito
Ohira Toshiaki
Takasawa Kiyotsugu
Lee Susan S. Y.
Nippon Steel Corporation
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