Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
1999-10-18
2001-03-20
Grimley, Arthur T. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
Reexamination Certificate
active
06205303
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an automatic electrifier cleaning method suitably applicable to the cleaning of an electrifier (electrifying device) of a printing apparatus based on an electrostatic developing system, and further to an image forming apparatus.
(2) Description of the Related Art
In general, contaminants such as toner and dust float in the interior of a printing apparatus (image forming apparatus), and these contaminants adhere to chassis, corona wires and other parts of a pre-electrifier and a transfer electrifier during the printing operation of the printing apparatus. Further, these contaminants accumulate with the use of the apparatus to cause a reduction of discharge efficiency, the discharge irregularity or the like in the electrifier, which leads to various troubles or problems such as the deterioration of print quality.
For this reason, in order to maintain the print quality of the printing apparatus, a need exists that a maintenance person or the user cleans or replaces the electrifier periodically. This electrifier cleaning work requires considerable skills, for that, for example, its corona wire is constructed using an extremely thin wire having a diameter of approximately 80 &mgr;m. Additionally, replacing the electrifier frequently is troublesome, which results in an increase in maintenance cost for the printing apparatus.
Thus, there has been known a printing apparatus which has been made such that a cleaning pad is brought into contact with a corona wire or the like of an electrifier and moved in parallel with the corona wire or the like through the use of a motor or the like to automatically clean the electrifier regularly.
However, in a conventional image forming apparatus, the electrifier is cleaned at a given interval, that is, the electrifier is cleaned automatically even in the case that print paper lies in the vicinity of an image forming drum, with the result that contaminants, such as toner and dust, removed from the electrifier by the cleaning adhere to the paper so that the print quality can deteriorate.
In addition, in the recent years, with the spread of laser printers and others, the using environment of the printing apparatus has come into variety or versatility, and an approach of cleaning the electrifier at a given interval like the above-described conventional automatic electrifier cleaning apparatus cannot remove the contamination of the electrifier sufficiently, thus making it difficult to eliminate various troubles and problems such as the deterioration of print quality resulting from a reduction of discharge efficiency and discharge irregularity of the electrifier.
Conceivably, the period of cleaning the electrifier would be shortened in order to prevent the discharge efficiency reduction and the discharge irregularity of the electrifier. However, this creates a problem in that the wear of its corona wire advances more quickly, which leads to shortening the life of the electrifier.
Still additionally, there is a need to once cease the printing operation of the printing apparatus at the cleaning of the electrifier, and in the case of cleaning the electrifier at a given interval like the conventional automatic electrifier cleaning apparatus, an interruption of the printing operation can take place periodically, which causes a reduction of the printing speed and interferes with the speed-up of the printing processing. This is particularly noticeable in the case of shortening the cycle of the cleaning of the electrifier.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of these problems, and it is therefore an object of this invention to provide an automatic cleaning method and an image forming apparatus which are capable of lengthening the life of an electrifier by designing the cleaning timings at the automatic cleaning of the electrifier.
For this purpose, in accordance with this invention, there is provided an automatic cleaning method of automatically cleaning, with a cleaning member, an electrifier which forms an image on medium, the method comprising the steps of measuring an electrification time of the electrifier after the last electrifier cleaning, discriminating whether or not the medium is located at an image forming station, and cleaning the electrifier with the cleaning member if the medium is absent at the image forming station after the electrification time reaches a first predetermined time.
Furthermore, in accordance with this invention, there is provided an image forming apparatus equipped with an electrifier which performs an electrifying operation to form an image on a medium, the image forming apparatus comprising a cleaning member for cleaning the electrifier, a drive mechanism for moving the cleaning member to clean the electrifier, an electrification time measuring section initialized at completion of cleaning of the electrifier for measuring an electrification time by the electrifier after the completion of the cleaning of the electrifier, a medium detecting section for discriminating whether or not the medium is located at an image forming station where an image is formed on the medium, and a control section for controlling the drive mechanism to move the cleaning member so as to clean the electrifier when the medium detecting section discriminates the absence of the medium at the image forming station after the electrification time measured by the electrification time measuring section reaches a first predetermined time.
Thus, the automatic cleaning method and the image forming apparatus according to this invention are capable of cleaning the electrifier without interfering with the printing operation and, hence, can prevent the reduction of the printing speed concurrently with preventing contaminants such as toner and dust produced by the cleaning from adhering to the medium to degrade the print quality, and additionally, are capable of suppressing the wear of the electrifying member to lengthen the life of the electrifier, thus accomplishing a high economy.
Besides, it is also appropriate that the cleaning member is operable to clean the electrifying member when an image forming operation of the image forming apparatus is stopped after the electrification time reaches a second predetermined time subsequent to the first predetermined time.
Accordingly, the automatic cleaning method and the image forming apparatus according to this invention permits the cleaning of the electrifier without hindering the printing operation and, hence, can eliminate the interference with the printing work.
In addition, it is also acceptable that, if the electrification time reaches a third predetermined time subsequent to the predetermined time without the stopping of the image forming operation, the image forming operation is temporarily stopped even before the electrifying member is cleaned with the cleaning member.
Accordingly, the automatic cleaning method and the image forming apparatus according to this invention can remove the contaminants such as toner and dust attached to the electrifying member to prevent the impairment of the print quality.
Still additionally, it is also acceptable that, when the image forming operation is to be temporarily stopped, the control section issues a request for a stop of image data transmission to a host unit which transmits image data to the image forming apparatus, or that the number of times of cleaning operation by the cleaning member is determined according to how the electrifier has been used, whereupon the cleaning operation performs by the cleaning member according to the determined number of times.
Accordingly, the automatic cleaning method and the image forming apparatus according to this invention can surely stop the image forming operation. Additionally, since the contamination of the electrifier can surely be removed according to how the electrifier has been used, it is possible to prevent the impairment of the print quality, and further, since the wear of the electrifying member
Chinzei Kiyoshi
Fujii Daisuke
Fuke Kenji
Armstrong, Westerman Hattori, McLeland & Naughton
Fujitsu Limited
Grimley Arthur T.
Tran Hoan
LandOfFree
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