The present invention relates to cleaning brushes for electrostatic copiers of the type utilizing photoreceptors, usually in the form of a rotatable drum or film type belts, zinc oxide, mylar, cadmium, etc., onto which toner particles are electrostatically deposited and which must be removed after each copy has been produced.
In the prior art relating to electrostatic copying machines, it has long been known that adequate means must be provided in the apparatus for removing toner particles from the photoconductive surface in a development station of such copiers and printers. For the most part, such stations employ rotating drums or belts onto which the toner particles are electrostatically deposited and carried through a printing cycle. The surface of such drums or belts have come to be made from a highly polished photosensitive material such as silenium, copper, etc., for drums and zinc oxide, mylar, cadmium, etc., for belts. Extreme care must be taken to keep the surfaces of these drums and belts very clean and protect them from fogging or scratching to insure good reproduction of copies through a large number of printing cycles. Thus, it is important that, after each printing cycle, any remaining toner particles be completely removed from the photosensitive surface without causing any damage or similarly introducing any contaminants to affect the surface of the photoreceptor.
To this end, the prior art has suggested a number of cleaning devices which have employed elaborate air venting and vacuuming implements as well as various types of brushes, many of which have been electrically or magnetically treated with chemicals, sprays, or the like, etc., to assist in the pick-up and removal of toner particles. While such devices have been useful in electrostatic copiers, the efficiency of the cleaning cycle has required improvement so as to minimize the downtime for the copying machine and reduce the frequency of required product maintenance changes.
To this end, the present invention provides an improved cleaning brush for the removal of toner and other particles from a photosensitive surface where, in a preferred embodiment, the brush is formed with two or more kinds of bristles. One kind is a conductive material while the others are compatible non-conductive materials wherein the conductive material fibers may be of shorter or comparable length relative to the non-conductive bristles. Also, in the preferred embodiment, the conductive and non-conductive bristles are intermingled and are supported to extend radially from a cylindrical core which is at least partially conductive or capable of transferring electrical charge throughout. Means may be provided to change the polarity of the conductive bristles to positive or negative alternately while cycling if necessary by connecting the core to a direct current source of the desired polarity or to ground or apply an alternating potential ( ) to the brush which would in effect neutralize the surrounding air to encourage the cleaning process.
The combination of conductive and non-conductive bristles, where the conductive bristles are shorter or of comparable length relative to the non-conductive fibers, will provide an optimum cleaning process and result in a reduction in the frequency of required machine maintenance.