Electrophotographic photoreceptor and electrophotographic image forming method and apparatus using the photoreceptor

An electrophotographic image forming method, comprising:

• charging an electrophotographic photoreceptor;
• irradiating said charged photoreceptor with imagewise light to form an electrostatic latent image on said photoreceptor;
• and
• developing said electrostatic latent image with a developer to form a visible image on said photoreceptor;
• wherein said photoreceptor comprises:
• an electroconductive substrate;
• and
• a photoreceptive layer overlying said substrate;
• wherein
• said photoreceptive layer comprises;
• a charge carrier generation layer comprising a charge carrier generation material, and
• a charge carrier transport layer comprising a charge carrier transport material,
• and wherein when an electric field of 2.5×105 V/cm to 5.5×105V/cm is applied to said charge carrier transport layer, the following relationship is satisfied:
• tCTL/μCTL≦2.2×102 V·s/m
• wherein tCTL represents a thickness of said charge carrier transport layer and μCTL represents a charge mobility of said charge carrier transport layer, and said charge carrier transport material of said charge carrier transport layer comprises an electron accepting material selected from the group consisting of chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-indeno-4H-indeno[1,2-b]thiophene-4one, and 1,3,7-trinitrodibenzothiophene-5,5-dioxide or a hole transporting material selected from the group consisting of 9-(p-diethylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styryl anthracene, styryl pyrazoline, a compound of formula (b), and a compound of formula (e):

An electrophotographic image forming process cartridge, comprising:

• an electrophotographic photoreceptor;
• a charger, which carries said photoreceptor;
• an imagewise light irradiating device, which irradiates said photoreceptor with imagewise light to form an electrostatic latent image on said photoreceptor;
• a developing device, which develops said latent image with a toner to form a toner image on said photoreceptor;
• a transferring device, which transfers said toner image on said photoreceptor onto a receiving material;
• a cleaning device, which cleans a surface of said photoreceptor;
• and
• a discharging device, which discharges a residual potential of said photoreceptor,
• wherein said photoreceptor comprises:
• an electroconductive substrate;
• and
• a photoreceptive layer overlying said substrate;
• wherein
• said photoreceptive layer comprises;
• a charge carrier generation layer comprising a charge carrier generation material, and
• a charge carrier transport layer comprising a charge carrier transport material, and wherein when an electric field of 2.5×105 V/cm to 5.5×105 V/cm is applied to said charge carrier transport layer, the following relationship is satisfied:
• tCTL/μCTL≦2.2×102V·s/m
• wherein tCTL represents a thickness of said charge carrier transport layer and μCTL represents a charge mobility of said charge carrier transport layer, and said charge carrier transport material of said charge carrier transport layer comprises an electron accepting material selected from the group consisting of chloranil, bromanil, tetracyanoethylene, tetracyanonquinodimethane, 2,4,7-trinitro-9-fluorene, 2,4,5,7-tetranotroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-indeno-4H-indeno[1,2-b]thiophene-4-one, and 1,3,7-trinitrodibenzothiophene-5,5-dioxide or a hole transporting material selected from the group consisting of 9-(p-diethylaminostyryl)anthracene, 1,1-bis-(4-dibenzylaminophenyl)propane, styrl anthracen, styrl pyrazoline, a compound of formula (b), and a compound of formula (e):