Organic photoreceptor, image forming apparatus, image forming method and image forming unit

An image forming apparatus comprising:

• (a) a plurality of image forming units, each of which corresponds to a different color toner and each of the image forming units comprising:
• (i) an organic photoreceptor,
• (ii) a charging member which provides electric charge to the organic photoreceptor and a surface of the organic photoreceptor,
• (iii) an image-wise exposure member which exposes light to a charged area of the organic photoreceptor so as to form an electrostatic latent image on the surface of the photoreceptor,
• (iv) a developing member which forms a toner image corresponding to the electrostatic latent image using a color toner on the surface of the organic photoreceptor, and
• (v) a cleaning member which removes the toner remaining on the surface of the organic photoreceptor;
• and
• (b) a transferring member which receives the toner image formed on the organic photoreceptor and transfers the toner image onto a transferring object,
• wherein, the organic photoreceptor comprises a conductive support on which a charge generating layer and a charge transporting layer are formed in that order and a changing rate of an exposure energy change (E600/100)n is not larger than 0.01 (μJ/cm2·μm) when a thickness of the charge transporting layer “n” decreases from 20 μm to 15 μm and when a surface potential of the organic photoreceptor varies from −600 V to −100 V, the changing rate of the exposure energy change (E600/100)n being defined by the following formula:
• (E600/100)20−(E600/100)15)/(20−15)

An image forming unit for an image forming apparatus comprising:

• (a) a plurality of image forming units, each of which corresponds to a different color toner and each of the image forming units comprising:
• (i) an organic photoreceptor,
• (ii) a charging member which provides electric charge to the organic photoreceptor and a surface of the organic photoreceptor,
• (iii) an image-wise exposure member which exposes light to a charged area of the photoreceptor so as to form an electrostatic latent image on the surface of the photoreceptor,
• (iv) a developing member which forms a toner image corresponding to the electrostatic latent image using a color toner on the surface of the organic photoreceptor, and
• (v) a cleaning member which removes the toner remaining on the surface of the organic photoreceptor;
• and
• (b) a transferring member which receives the toner image formed on the-organic photoreceptor and transfers the toner image onto a transferring object,
• wherein, the organic photoreceptor comprises a conductive support on which a charge generating layer and a charge transporting layer are formed in that order and a changing rate of an exposure energy change (E600/100)n is not larger than 0.01 (μJ/(cm2·μm)) when a thickness of the charge transporting layer “n” decreases from 20 μm to 15 μm and when a surface potential of the organic photoreceptor varies from −600 V to −100 V, the changing rate of the exposure energy change (E600/100)n being defined by the following formula:
• ((E600/100)20−(E600/100)15)/(20−15)