Electrophotographic photoreceptor, and image forming apparatus and process cartridge using the same

An image-forming apparatus comprising:

• an electrophotographic photoreceptor comprising an organic photosensitive layer and a surface layer provided at a surface of the organic photosensitive layer;
• a charging unit for charging a surface of the electrophotographic photoreceptor;
• an electrostatic latent image forming unit for forming an electrostatic latent image on the charged electrophotographic photoreceptor;
• a developing unit for forming a toner image by developing the electrostatic latent image with a toner-containing developer;
• a transfer unit for transferring the toner image onto a recording medium;
• a fixing unit for fixing the toner image onto the recording medium;
• and
• a cleaning unit for cleaning the surface of the photoreceptor after transferring the toner image onto the recording medium, the surface layer including a first layer which is provided at a photosensitive layer side and has a refractive index of n1 and a second layer which is provided at an opposite side of the first layer to the organic photosensitive layer and has a refractive index of n2, and the photoreceptor satisfying the following Inequalities (6) to (8):
• |n0−n2|>0.1 Inequality (6):
• n0<n1<n2, or n0>n1>n2 Inequality (7):
• λ/(8×n1)+a+λ/(2×n1)≦d1≦3×λ(8×n1)+a×λ/(2×n1) Inequality (8):
• where, in Inequalities (6) to (8), n0 represents the refractive index of the organic photosensitive layer, n1 represents the refractive index of the first layer, n2 represents the refractive index of the second layer, d1 represents the film thickness (nm) of the first layer, a represents an integer of 0 or more, and λ represents the wavelength (nm) of light with which the surface of the photoreceptor is irradiated when an electrostatic latent image is formed,
• wherein
• the thickness of the second layer is 50 nm or more, and
• at least one of the first layer or the second layer comprises Ga, oxygen and hydrogen.

A process cartridge comprising an electrophotographic photoreceptor an organic photosensitive layer and a surface layer provided at a surface of the organic photosensitive layer, the process cartridge being detachably attached to a main body of an image forming apparatus, the surface layer including a first layer which is provided at a photosensitive layer side and has a refractive index of n1 and a second layer which is provided at an opposite side of the first layer to the organic photosensitive layer and has a refractive index of n2, and the photoreceptor satisfying the following Inequalities (9) to (11):

• |n0−n2|>0.1 Inequality (9):
• n0<n1<n2, or n0>n1>n2 Inequality (10):
• λ/(8×n1)+a×λ/(2×n1)≦d1≦3×λ/(8×n1)+a×λ/(2×n1) Inequality (11):
• where, in Inequalities (9) to (11), n0 represents the refractive index of the organic photosensitive layer, n1 represents the refractive index of the first layer, n2 represents the refractive index of the second layer, d1 represents the film thickness (nm) of the first layer, a represents an integer of 0 or more, and λ represents the wavelength (nm) of light with which the surface of the photoreceptor is irradiated when an electrostatic latent image is formed,
• wherein
• the thickness of the second layer is 50 nm or more, and
• at least one of the first layer or the second layer comprises Ga, oxygen and hydrogen.