Abstract: The present invention provides an electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, the photosensitive layer comprising a specific hole transferring material and/or electron transferring material and a binding resin of a polyester resin which is a substantially linear polymer obtained by using a specific dihydroxy compound represented by the general formula (1): wherein R1 is an alkylene group having 2 to 4 carbon atoms; and R2, R3, R4 and R5 are the same or different and indicate a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or an aralkyl group or the like. This photosensitive material is improved in sensitivity, and is also superior in adhesion to conductive substrate as well as mechanical strength such as wear resistance, etc.

Abstract: The present invention provides a naphthoquinone derivative represented by the general formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are as defined in the specification. An electrophotosensitive material containing this naphthoquinone derivative as an electron transferring material has high sensitivity.

Abstract: The photosensitive material of the present invention is provided in contact with a developing roller and has a surface potential decay characteristic in which when the photosensitive material is charged to a surface potential of 800 V and is contacted with the developing roller to which a voltage (VR) is applied, the surface potential (VD) of the photosensitive material after contacting is represented by the formula (1):VD.gtoreq.800.times.EXP (0.00235.times.VR).By using this photosensitive material, a transverse black stripe in the tip of the transfer paper is prevented and it is possible to form an image having excellent image quality and image density.

Abstract: The present invention provides a naphthoquinone derivative represented by the general formula (I): ##STR1## wherein R.sup.1 and R.sup.2 are as defined in the specification. An electrophotosensitive material containing this naphthoquinone derivative as an electron transferring material has high sensitivity.

Abstract: The present invention provides an electrophotosensitive material comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, the photosensitive layer comprising a specific hole transferring material and/or electron transferring material and a binding resin of a polyester resin which is a substantially linear polymer obtained by using a specific dihydroxy compound represented by the general formula (1): ##STR1## wherein R.sup.1 is an alkylene group having 2 to 4 carbon atoms; and R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and indicate a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group or an aralkyl group or the like. This photosensitive material is improved in sensitivity, and is also superior in adhesion to conductive substrate as well as mechanical strength such as wear resistance, etc.

Abstract: The present invention provides a tryptoanthrinimine derivative represented by the general formula (Y): ##STR1## wherein R.sup.A to R.sup.M are as defined. Such a derivative of the general formula (Y) is superior in electron transferring capability. Accordingly, an electrophotosensitive material comprising a photosensitive layer containing this derivative (Y) is superior in sensitivity.

Abstract: An electrophotographic method in which an electrostatic latent image on a single-layer organic photosensitive material is developed while applying a developing bias voltage of the same polarity as the polarity of the charge of the photosensitive material. The developing bias voltage is set to be higher than a potential that corresponds to a point where a curve approximating the zone of a large amount of exposure to light and a curve approximating the zone of a small amount of exposure to light in a light decay characteristics curve intersect each other.

Abstract: The present invention provides a novel trinitrofluorenonimine derivative represented by the general formula (1): ##STR1## wherein R.sup.0 is an alkyl group; and R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are the same or different and indicate a hydrogen atom, an alkyl, an alkoxy, an aryl, an aralkyl, a halogen atom or an alkyl halide. This derivative is superior in electron transferring capability and compatibility with binding resin. Accordingly, an electrophotosensitive material comprising this derivative as an electron transferring material is superior in sensitivity.

Abstract: There is disclosed an electrophotosensitive material using a binding resin of a bisphenol C type, bisphenol Z type, bisphenol Z type containing a substituent or bisphenol C-copolymer type polycarbonate in combination with a hole transferring material of a specific benzidine or phenylenediamine derivative. This photosensitive material is superior in mechanical strength and repeat characteristics and has a high glass transition temperature and a high sensitivity.

Abstract: According to the present invention, there is provided a novel tryptoanthorine derivative represented by the formula: ##STR1## wherein R.sup.1a, R.sup.1b, R.sup.1c, R.sup.1d, R.sup.2a, R.sup.2b, R.sup.2c, and R.sup.2d are the same or different and indicate a hydrogen atom, an alkyl group or a halogenated alkyl group; provided that R.sup.1a, R.sup.1b, R.sub.1c and R.sup.1d do not indicate a hydrogen atom, simultaneously. Tryptoanthorine and a derivative thereof are suitably used for an electrophotosensitive material because of their excellent electron transferring capability.

Abstract: A compact electrophotographic apparatus is attained by decreasing the diameter of the photosensitive drum so that a plurality of rotations of the drum are required to produce a single sheet image. Images of excellent quality, especially with respect to the lack of stepwise density decrease across the image due to multiple drum rotations per image, are achieved by providing for discharge of the photosensitive drum so that the residual potential on the drum is 10% or less of the charged surface potential after discharge on the first rotation of the drum and the increase in the residual potential is not more than 30% after discharge on the last rotation of a sheet making cycle.