When photocopiers were first used, charging of the photoreceptor or photoconductive surface was usually accomplished by rubbing the photoconductive surface with electronic charging materials such as rabbit fur. Today, much more sophisticated charging means are used, in particular, corona charging devices such as corotrons, scorotrons, etc. Generally, the corona charger comprises a charge-emitting wire or an array of charge-emitting pins located in close proximity to a corona grid. The pins emit the charge and convey this charge to a conductive grid, which provides uniformity of charge across the entire used surface of the photoreceptor. The grid is specifically configured so as to have uniform charge-emitting capabilities across its entire longitudinal surface. It is especially important to maintain the grid surface and wire in condition where they will provide this uniform charge distribution across the photoreceptor or photoconductive surface. Once a uniform charge is placed by the grid across the photoreceptor surface, the remainder of the imaging process is followed, i.e. exposure of image, dissipation of charge in image configuration, contact with toner and fixing of toner image on a paper or receptive surface.
Contamination of the pins, wire, or inner and outer sides of the grid could lead to print quality defects, such as streaks, image quality defects and other performance problems. Examples of image quality failures would be half tone non-uniformities and white and dark streaks in the final image. Also, the life of the corona-charging mechanism can be adversely affected if the wire and grid are not kept uniformly clear of contaminants such as dust and toner.
There are used today various automatic corona-cleaning methods and apparatus to remove the toner build up and other contaminates from the wire and grid. Traditionally, these corona-cleaning devices have focused on cleaning the pins, wires and surface of the corona grid. Usually, in these automatic cleaners, a brush is used to clean the grid while a pad located below the brush is used to clean the pins or the corona wire. They move together when the shaft and brush-pad holder are moved. A winding on a lead shaft is used to project the brush and pad holder along the longitudinal plan of the wire and grid.
Currently, the existing charge scorotron assembly cleaner has design flaws that cause high torque conditions which, in turn, cause field issues, especially during power on, power off (POPO) conditions or paper jamming. A current prior art design enables the machines to cycle the above scorotron cleaner every 1000-1500 copies to clean the grid, pins and charge scorotron wire. However, if and when a paper jam or power off condition occurs, the machine is “dumb” and does not have a sensor or have the capability to tell where in position the cleaner assembly is when machine is ready then for printing. Thus, the machine automatically instructs the auto clean device to turn on for 33 seconds to complete one cycle (back and forth). If the auto clean device is moved away from the home position, i.e. cleaning when jammed, the machine does not know this and still cycles the auto-cleaner for 33 seconds. Currently, there is a high torque issue with this prior art system and device with the added cycle time due to jamming or other issues. This will, most likely, eventually overstress the system causing breakage of the motor gears and cause the machine to fault. This equals customer dissatisfaction and expensive repairs.
The present embodiments of this invention will solve this potential quality repair and customer dissatisfaction issue. In addition, in one embodiment making the device and shaft of this invention by plastic injection molding rather than metal will save a considerable amount of money; over 20% of previous costs. This amount is based on current projections but may, in fact, exceed this projection.
USPTO Backgrounds
USPTO Backgrounds