Electrophotographic photoreceptor, method for manufacturing the electrophotographic photoreceptor, and image forming apparatus and process cartridge using the electrophotographic photoreceptor

• US 20040185358A1
• Filed: 03/19/2004
• Published: 09/23/2004
• Est. Priority Date: 03/19/2003
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Kami, Hidetoshi
• Granted Patent: US 7,270,924 B2
• Time in Patent Office: Days
• US Class Current: 430/58.7
• CPC Class Codes: G03G 5/04 Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
• CPC Class Codes: G03G 5/0525 Coating methods
• CPC Class Codes: G03G 5/075 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds G03G5/078 takes precedence
• CPC Class Codes: G03G 5/0764 triarylamine
• CPC Class Codes: G03G 5/0765 alkenylarylamine
• CPC Class Codes: G03G 5/0767 comprising hydrazone moiety

Abstract

A photoreceptor including an electroconductive substrate, a photosensitive layer located overlying the substrate, and a protective layer overlying the photosensitive layer, wherein the photoreceptor has a property such that when the photoreceptor is charged so as to have a potential of −700 V and then exposed to light with exposure of 0.4 μJ/cm², the potential (P_L) of a lighted portion of the photoreceptor decreases at a rate not greater than 700 V/sec during a time period of from a time 35 msec after the exposure to the transition time of the photoreceptor. An image forming apparatus and a process cartridge including the photoreceptor are also provided.

Claims

1. A photoreceptor comprising:

an electroconductive substrate;

a photosensitive layer located overlying the substrate; and

a protective layer located overlying the photosensitive layer,

wherein the photoreceptor has a property such that when the photoreceptor is charged so as to have a potential of −

700 V and then exposed to light with exposure of 0.4 μ

J/cm², the potential (P_L) of a lighted portion of the photoreceptor decreases at a rate not greater than 700 V/sec during a time period of from a time 35 msec after the exposure to a transition time of the photoreceptor.

2. The photoreceptor according to claim 1, wherein the protective layer comprises a charge transport material.

3. The photoreceptor according to claim 2, wherein the charge transport material is a charge transport polymer.

4. The photoreceptor according to claim 3, wherein the charge transport polymer has a triaryl amine structure.

5. The photoreceptor according to claim 1, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer, which are overlaid.

6. The photoreceptor according to claim 5, wherein the charge transport layer has a charge mobility (μ

) not less than 1.2×

10<sup>−

5</sup> cm²/V·

sec at an electric field strength of 4×

10⁵ V/cm, and wherein dependence (β

) of the charge mobility on the electric field strength (E) is not greater than 1.6×

10<sup>−

3</sup>, wherein β

=log μ

/E^1/2.

7. A method for manufacturing the photoreceptor according to claim 1, comprising:

spray-coating a protective layer coating liquid including a solvent, which dissolves a resin included in the photosensitive layer, on the photosensitive layer, wherein the following relationship is satisfied;

1.3<

W1/W2<

1.9

wherein W1 represents a weight of the coated protective layer, which is measured after coating the protective layer coating liquid and allowing the coated liquid to settle for 1 hour under conditions of 25±

3°

C. and 53±

5% RH; and

W2 represents a weight of the coated protective layer, which is measured after coating the protective layer coating liquid and drying the coated liquid for 10 minutes or more at a temperature not lower than a boiling point of the solvent.

8. An image forming apparatus comprising:

the photoreceptor according to claim 1;

a charger configured to charge the photoreceptor;

a light irradiator configured to irradiate the photoreceptor with imagewise light to form an electrostatic latent image on the photoreceptor;

an image developer configured to develop the electrostatic latent image with a toner to form a toner image on the photoreceptor; and

a transfer device configured to transfer the toner image to a receiving material optionally via an intermediate transfer medium,

wherein an interval between the light irradiation step and the development step is not greater than 100 ms.

9. The image forming apparatus according to claim 8, wherein the transition time of the photoreceptor is not greater than the interval between the light irradiation step and the development step.

10. A process cartridge comprising:

the photoreceptor according to claim 1;

and

at least one of a charger configured to charge the photoreceptor;

a light irradiator configured to irradiate the photoreceptor with imagewise light to form an electrostatic latent image on the photoreceptor;

an image developer configured to develop the electrostatic latent image with a toner to form a toner image on the photoreceptor;

a transfer device configured to transfer the toner image to a receiving material optionally via an intermediate transfer medium;

a cleaner configured to clean a surface of the photoreceptor; and

a discharger configured to reduce charges remaining on the photoreceptor.