Photoreceptor cleaning device for electrophotographic copying apparatus of the dry cleaning agent type

Claim 1

In electrophotographic copying apparatus of the dry toner image transfer type, in combination, a. a photoreceptor unidirectionally movable along a closed endless path and undergoing two complete revolutions around said path during each cycle of copying operation; and b. means, disposed in succession along said path so as to be traversed successively by said photoreceptor during each complete revolution thereof around said path, for erasing charge from said photoreceptor, charging said photoreceptor, exposing said photoreceptor in charged condition to form an electrostatic latent image thereon, developing the electrostatic latent image on said photoreceptor, and transfer printing the developed image; wherein the improvement comprises: c. said charging, exposing, and transfer printing means comprising means for charging said photoreceptor, forming a latent image thereon and transfer printing a developed image only once in each cycle of copYing operation, during only the first of the two successive revolutions of said photoreceptor around said path constituting said cycle, and being inoperative during the second of said two successive revolutions constituting said cycle; d. said erasing means comprising means for erasing charge from said photoreceptor at least during the second of said two successive revolutions of said photoreceptor such that said photoreceptor traverses said developing means in charged condition during said first revolution and in charge-erased condition during said second revolution in each cycle of copying operation; and e. said developing means comprising a magnetic brush for transferring dry toner particles to said photoreceptor to develop an electrostatic latent image thereon when said photoreceptor traverses the developing means in charged condition and for removing residual toner particles from said photoreceptor to clean said photoreceptor when said photoreceptor traverses the developing means in charge-erased condition, such that said magnetic brush develops an image on the photoreceptor during the first, and cleans the photoreceptor during the second, of the two successive revolutions of the photoreceptor constituting one cycle of copying operation.