CHARGING DEVICE, IMAGE FORMING UNIT AND IMAGE FORMING APPARATUS

• US 20150125184A1
• Filed: 11/05/2014
• Published: 05/07/2015
• Est. Priority Date: 11/06/2013
• Status: Active Grant

• Current Assignee: OKI Electric Industry Company Limited
• Original Assignee: Oki Data Corporation (OKI Electric Industry Company Limited)
• Inventors: HIGAKI, Toshimasa
• Granted Patent: US 9,280,078 B2
• Time in Patent Office: Days
• US Class Current: 399/176
• CPC Class Codes: G03G 15/0208 by contact, friction or induction, e.g. liquid charging apparatus
• CPC Class Codes: G03G 15/0216 by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers
• CPC Class Codes: G03G 15/0233 Structure, details of the charging member, e.g. chemical composition, surface properties
• CPC Class Codes: G03G 15/025 by bringing a charging member in the vicinity with the member to be charged, e.g. proximity charging, forming microgap
• CPC Class Codes: G03G 15/1685 Structure, details of the transfer member, e.g. chemical composition
• CPC Class Codes: G03G 2215/021 by contact, friction or induction
• CPC Class Codes: G03G 2221/183 Process cartridge

Abstract

A charging device includes a charging member that charges a surface of an image bearing body. The charging member includes a rotation shaft applied with a voltage, and a resilient conductive layer provided on an outer circumferential surface of the rotation shaft. The resilient conductive layer charges the surface of the image bearing body. The resilient conductive layer has a plurality of high resistance regions arranged at intervals in an axial direction of the rotation shaft.

Claims

1. A charging device comprising:

a charging member that charges a surface of an image bearing body,

wherein the charging member comprises a rotation shaft applied with a voltage, and a resilient conductive layer provided on an outer circumferential surface of the rotation shaft, the resilient conductive layer charging the surface of the image bearing body,

wherein the resilient conductive layer has a plurality of high resistance regions arranged at intervals in an axial direction of the rotation shaft.

2. The charging device according to claim 1, wherein the high resistance regions include cracks formed on of the resilient conductive layer and extending in a rotating direction of the charging roller.

3. The charging device according to claim 2, wherein the cracks have a depth greater than or equal to 20 μ

m from the surface of the resilient conductive layer, and

wherein at least five cracks are provided in an area of 5 mm² on the surface of the resilient conductive layer parallel to the axial direction.

4. The charging device according to claim 2, wherein the cracks have a depth greater than or equal to 20 μ

m from the surface of the resilient conductive layer, and

wherein at least one crack is provided in an area of 1 mm² on the surface of the resilient conductive layer parallel to the axial direction.

5. The charging device according to claim 2, wherein the cracks are formed by irradiating the surface of the resilient conductive layer with ultraviolet rays.

6. The charging device according to claim 2, wherein the resilient conductive layer has a plurality of grooves on the surface thereof, the grooves extending in the rotational direction of the charging roller,

wherein the cracks are formed in the grooves.

7. The charging device according to claim 2, wherein a protection film is formed on the surface of the resilient conductive layer, and

wherein the cracks are formed in the protection film.

8. The charging device according to claim 7, wherein the protection film is an oxide film.

9. The charging device according to claim 2, wherein the voltage applied to the rotation shaft is a direct voltage.

10. The charging device according to claim 2, wherein the resilient conductive layer contains 20 weight parts or more of diene-based rubber with respect to 100 weight parts epichlorohydrin rubber.

11. The charging device according to claim 2, wherein the resilient conductive layer contains 150 weight parts or less of diene-based rubber with respect to 100 weight parts epichlorohydrin rubber.

12. An image forming unit comprising the charging device according to claim 1.

13. An image forming apparatus comprising the charging device according to claim 1.