The Impact of Cleaning on Copy Quality

The process of cleaning is composed of two aspects: eliminating residual charge and cleaning residual toner, if one of these aspects goes wrong, the next copying process will fail, and the copies will have overlap, image of the previous original, etc. Corona discharge with the opposite polarity of the main charge (also known as "power elimination") is adopted, while the power elimination lamp is used to fully expose the photoconductor after the transfer. This method is an effective way to eliminate the residual charge, and is used by most copiers. In terms of cleaning residual toner, there are some methods as follows.

(1) Scraper cleaning. A scraper made of rubber and plastic material with thickness of about 2mm is used to scrape the residual toner off the surface of the photoelectric conductor by contacting the surface of the photoelectric conductor at a certain angle and maintaining a small but uniform line pressure. The scraped residual toner is recycled into the waste toner cartridge. This is the method used by most copiers. Since the residual toner scraped off is fully exposed in the air and has been exposed to strong electric field in the process of developing and transferring, its performance will be greatly degraded, and dust and paper dust may be mixed with it. When discarded, care should be taken to use plastic bags sealed to avoid pollution of the environment.

(2) brush cleaning. The roller brush made of animal hair or fiber hair is the method more often used in large engineering drawing copiers. The requirements for the brush are softness and stiffness, no static electricity when rubbing with the surface of photoelectric conductor, better toner inclusion, and the waste powder can be removed from the brush easily by the suction and discharge equipment. Because of the narrow range of materials for making brushes and more auxiliary devices for handling waste powder, generally small and medium-sized copiers do not use this method.

(3) Foam soft roller cleaning. This is the method mostly used for wet copiers. It is made of foam material (such as sponge), because the foam pores can absorb liquid, and the liquid can be discharged through certain extrusion, so that the colorant particles can be retained in the soft roller, and the colorant particles can be flushed out with diluent when necessary.

(4) Magnetic brush recycling. This is to clean and recycle the residual toner with the developing magnetic brush before a new copying process starts. Since the waste toner is to be reused, it is suitable for copiers using short-life carriers. In addition, the magnetic brush cleaning must make the photoconductor turn one more turn before the next copy process, which can be used for low-speed copiers but is not applicable for high-speed copiers.

(5) Magnetic roller recycling. This is a method more often used in Canon copiers that use magnetic single-component developer. It uses a permanent magnetic roller in the cleaning section to recover the residual toner by adsorption into the waste cartridge, and this method is ineffective for non-conductive toner.

(6) Magnetic strip recovery of waste carriers. In theory, the carrier in the two-component developer is not consumed, but in practice, a small amount of carrier particles will still be attached to the surface of the photoconductor during the development process and affect the image quality of the later copies. In this regard, some copiers use a magnetic strip in the cleaning department to adsorb the residual carrier, and the maintenance personnel and operators will take it out and clean it up to a certain extent.

To sum up, the six basic processes of copying are the basic and decisive factors that affect the quality of copied products.