Electrophotographic image forming apparatus, photoreceptor therefor and method for manufacturing the photoreceptor

#1. Field of the Invention

#The present invention relates to an electrophotographic image forming apparatus and a process cartridge for electrophotographic image forming apparatus. In particular, the present invention relates to an electrophotographic image forming apparatus using a proximity charger, and a process cartridge therefor. In addition, the present invention also relates to a photoreceptor for use in the electrophotographic image forming apparatus, and to a method for manufacturing the photoreceptor.

#2. Discussion of the Background

#Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the detailed description when considered in connection with the accompanying drawings in which like reference characters designate like corresponding parts throughout and wherein:

#FIGS. 1 to 3 are schematic views illustrating cross-sections of embodiments of the photoreceptor for use in the image forming apparatus of the present invention;

#FIG. 4 is a schematic view illustrating an embodiment of the configuration of the charging roller and the photoreceptor in the image forming apparatus of the present invention;

#As mentioned above, when contact charging devices are used for electrophotographic image forming apparatus, problems which occur are that a toner film is formed on the charger and a charger deforms, resulting in uneven charging or defective charging. In attempting to solve these problems, proximity charging devices have been proposed. However, there is no proximity charging device which has a low cost and a simple structure and in which a gap is stably formed between the charger and the photoreceptor used and maintained even when used for a long period of time.

#As a result of the present inventors' investigation, it is discovered that by providing a gap forming member on both end portions (i.e., non-image portions) of the periphery surface of a photoreceptor and arranging the charging roller such that the charging roller and the image forming portion of the photoreceptor have a specific positional relationship, the above-mentioned problems can be solved. Thus, the present invention is made.

#In the present invention, the image forming portion of the photoreceptor is defined as an area of the photoreceptor in which charging, imagewise irradiation, developing and transferring processes are performed. In addition, the ends of the image forming portion are defined as the outermost side edges of the image forming portion. If the outermost side edges are different for the image forming portions of the charging, imagewise light irradiation, developing and transferring processes, the ends of the image forming portion are defined as the most inside edges among the outermost edges. The photoreceptor may be a drum-form photoreceptor or a belt-form photoreceptor supported by a driving and/or driven roller, and the charging, developing, and transferring processes are performed such that the ends of their image forming portions are substantially parallel to the rotating direction of the photoreceptor. In addition, imagewise light irradiation is also performed such that the side ends of the largest optical solid image are substantially parallel to the rotating direction of the photoreceptor. At this point, the term “substantially” means that the end lines are almost parallel to the rotating direction of the photoreceptor although the end lines are zigzagged due to movements of the elements such as developing roller in the direction perpendicular to the rotating direction, low-precision elements of the light irradiator, etc.