Phthalocyanine crystal, and electrophotographic photoreceptor, electrophotographic photoreceptor cartridge and image-forming device using the same

An electrophotographic photoreceptor, comprising:

• an electroconductive substrate and
• a photosensitive layer having a film thickness of 35±2.5 μm on the substrate,
• wherein a half-decay exposure E½ at a temperature of 25° C. and a relative humidity of 50% rh satisfies an expression (1):
• E½≦0.059 (1),
• an absolute value of a difference in surface potential at exposure E½ does not exceed 50V in an exposure range of from 0 to 10 times the half-decay exposure E½ when a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 50% rh is compared with a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 10% rh, and
• E½ is exposure (μJ/cm2) of light having a wavelength of 780 nm required for decaying an absolute value |V0| of a surface potential V0 of the photoreceptor from 550V to 275V.

An electrophotographic photoreceptor, comprising:

• an electroconductive substrate and
• a photosensitive layer having a film thickness of 30±2.5 μm on the substrate,
• wherein a half-decay exposure E½ at a temperature of 25° C. and a relative humidity of 50% rh satisfies an expression (2):
• E½≦0.061 (2),
• an absolute value of the difference in surface potential at exposure E½ does not exceed 50V in an exposure range of from 0 to 10 times the half-decay exposure E½ when a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 50% rh is compared with a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 10% rh, and
• E½ is exposure (μJ/cm2) of light having a wavelength of 780 nm required for decaying an absolute value |V0| of a surface potential V0 of the photoreceptor from 550V to 275V.

An electrophotographic photoreceptor, comprising:

• an electroconductive substrate and
• a photosensitive layer having a film thickness of 25±2.5 μm on the substrate,
• wherein a half-decay exposure E½ at a temperature of 25° C. and a relative humidity of 50% rh satisfies an expression (3):
• E½≦0.066 (3),
• an absolute value of a difference in surface potential at exposure E½ does not exceed 50V in an exposure range of from 0 to 10 times the half-decay exposure E½ when a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 50% rh is compared with a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 10% rh, and
• E½ is exposure (μJ/cm2) of light having a wavelength of 780 nm required for decaying an absolute value |V0| of a surface potential V0 of the photoreceptor from 550V to 275V.

An electrophotographic photoreceptor, comprising:

• an electroconductive substrate, and
• a photosensitive layer having a film thickness of 20±2.5 μm on the substrate,
• wherein a half-decay exposure E½ at a temperature of 25° C. and a relative humidity of 50% rh satisfies an expression (4):
• E½≦0.079 (4),
• an absolute value of a difference in surface potential at exposure E½ does not exceed 50V in an exposure range of from 0 to 10 times the half-decay exposure E½ when a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 50% rh is compared with a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 10% rh, and
• E½ is exposure (μJ/cm2) of light having a wavelength of 780 nm required for decaying an absolute value |V0| of a surface potential V0 of the photoreceptor from 550V to 275V.

An electrophotographic photoreceptor, comprising:

• an electroconductive substrate, and
• a photosensitive layer having a film thickness of 15±2.5 μm formed on the substrate,
• wherein a half-decay exposure E½ at a temperature of 25° C. and a relative humidity of 50% rh satisfies an expression (5):
• E½≦0.090 (5),
• an absolute value of a difference in surface potential at exposure E½ does not exceed 50V in an exposure range of from 0 to 10 times the half-decay exposure E½ when a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 50% rh is compared with a photo-induced discharge curve at a temperature of 25° C. and a relative humidity of 10% rh, and
• E½ is exposure (μJ/cm2) of light having a wavelength of 780 nm required for decaying an absolute value |V0| of a surface potential V0 of the photoreceptor from 550V to 275V.

An electrophotographic photoreceptor cartridge comprising:

• an electrophotographic photoreceptor;
• and
• at least one of:
• a charge unit for charging the electrophotographic photoreceptor,
• an exposure unit for exposing the charged electrophotographic photoreceptor to form an electrostatic latent image thereon,
• a development unit for developing an electrostatic latent image formed on the electrophotographic photoreceptor, and
• a cleaning unit for cleaning an upper side of the electrophotographic photoreceptor,
• wherein the electrophotographic photoreceptor comprises an electroconductive substrate and a photosensitive layer on the substrate,
• the photosensitive layer comprises a phthalocyanine crystal, and
• the phthalocyanine crystal is obtained by a process comprising bringing a phthalocyanine crystal precursor into contact with an aromatic aldehyde compound, thereby converting a crystal form of phthalocyanine.

An image-forming device, comprising:

• an electrophotographic photoreceptor,
• a charge unit for charging the electrophotographic photoreceptor,
• an exposure unit for exposing the charged electrophotographic photoreceptor to form an electrostatic latent image thereon, and
• a development unit for developing the electrostatic latent image,
• wherein the electrophotographic photoreceptor comprises an electroconductive substrate and a photosensitive layer on the substrate,
• the photosensitive layer comprises a phthalocyanine crystal, and
• the phthalocyanine crystal is obtained by a process comprising bringing a phthalocyanine crystal precursor into contact with an aromatic aldehyde compound, thereby converting a crystal form of phthalocyanine.