Photocopying – Including fiber optics
Patent
1980-04-23
1982-09-28
Braun, Fred L.
Photocopying
Including fiber optics
250324, 355 14CH, 361229, G03G 1500
Patent
active
043516033
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an electronic copying apparatus, and more particularly, to an electronic copying apparatus of the type in which an electrostatic latent image is formed on a record medium and then developed with a toner powder, and a visible image formed on the record medium as a result of the developing process is transferred onto a transfer member and subsequently the record medium is neutralized by utilizing a corona discharge.
BACKGROUND TECHNOLOGY
An electronic copying apparatus is known in the prior art which is of the type wherein an electrostatic latent image is formed on a record medium and developed with a toner powder to produce a visible image on the record medium, which visible image is then transferred onto a transfer member, and wherein the record medium is subsequently neutralized by utilizing a corona discharge. The record medium is in the form of a drum or belt which undergoes an angular movement to cause a cyclic movement of its peripheral surface during which the copying process takes place.
An electrostatic latent image may be formed through a series of charging and exposure steps for a record medium which comprises a photoconductive, light sensitive member, and, in one case, may be formed by a selective charging of the surface of the record medium with a recording electrode such as a multistylus for a record medium which comprises a dielectric material.
A problem encountered in an electronic copying apparatus of the type described is dispersion of the toner powder into the copying apparatus and a marring of a neutralizer by the toner powder. The problem will be considered in more detail with reference to the drawings.
FIG. 1 illustrates an example of an electronic copying apparatus of the type described. A record medium 1 which comprises a photoconductive, light sensitive member is in the form of a drum which is rotatable in a direction indicated by an arrow. During a copying operation, the peripheral surface of the record medium 1 which rotates in the direction of the arrow is uniformly charged by a corona discharge from a corona charger 2, and is then irradiated with a light image which is formed by an exposure optical system 3. An electrostatic latent image thus formed on the record medium 1 is then developed with a toner powder by means of a developer unit 4, and the resulting visible image is transferred on a transfer member or paper 8 by means of a transfer unit 5. The visible image which is transferred to the transfer paper 8 is fixed by utilizing a fixing unit, not shown. The transfer paper 8 carrying the fixed visible image is delivered externally of the apparatus, thus providing a single copy.
After transfer of the visible image, the record medium 1 is neutralized by a corona discharge from a neutralizer 6, and any residual toner is removed by a cleaning unit 7.
However, a problem arises in conjunction with the use of the neutralizer 6 in that a dispersion of the toner powder into the apparatus and a marring of the neutralizer 6 by the toner powder may result.
Specifically, after the transfer of the visible image, a quantity of non-transferred toner remains on the peripheral surface of the record medium as it moves toward the location of the neutralizer 6. A majority of such non-transferred toner is distributed in those areas of the peripheral surface of the record medium which have not been brought into contact with the transfer member during the transfer step. An increased quantity of toner may remain in such areas where the transfer paper 8 has an area less than that of the visible image formed on the peripheral surface of the record medium or where the copying process is practised while leaving an original receptacle open which causes a dense deposition of the toner in border areas on the record medium so as to frame the visible image corresponding to the original. Even during a normal copying operation, there exists a certain potential, and hence a quantity of toner, around an image region. Referring to FIG. 2 which illustrates a transfer st
REFERENCES:
patent: 2701764 (1955-02-01), Carlson
patent: 2836725 (1958-05-01), Vyverberg
patent: 3339069 (1967-08-01), Hayne et al.
patent: 4201465 (1980-05-01), Oyama et al.
patent: 4260235 (1981-04-01), Stack
Braun Fred L.
Ricoh & Company, Ltd.
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