Image forming apparatus

• US 10,401,779 B2
• Filed: 08/03/2018
• Issued: 09/03/2019
• Est. Priority Date: 08/28/2017
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Katagiri, Shinji, Yoshida, Tsuguhiro, Tetsuno, Shuichi, Tanaka, Takayuki, Ikeda, Takahiro, Motohashi, Satoru, Furukawa, Takumi
• Primary Examiner(s): Lindsay, Jr., Walter L
• Assistant Examiner(s): Eley, Jessica L
• Application Number:
  US16/054,676
• Publication Number:
  US 20190064726A1
• Time in Patent Office: 396 Days
• CPC Class Codes: G03G 15/0121 for developing
• CPC Class Codes: G03G 15/0126 using a solid developer
• CPC Class Codes: G03G 15/0131 for transferring a pattern to a second base
• CPC Class Codes: G03G 15/0189 primary transfer to an intermediate transfer belt G03G15/0184 takes precedence
• CPC Class Codes: G03G 15/0225 provided with means for cleaning the charging member
• CPC Class Codes: G03G 15/0233 Structure, details of the charging member, e.g. chemical composition, surface properties
• CPC Class Codes: G03G 15/0808 characterised by the developer supplying means, e.g. structure of developer supply roller
• CPC Class Codes: G03G 15/161 with means for handling the intermediate support, e.g. heating, cleaning, coating with a transfer agent
• CPC Class Codes: G03G 15/80 Details relating to power supplies, circuits boards, electrical connections
• CPC Class Codes: G03G 21/0064 using the developing unit, e.g. cleanerless or multi-cycle apparatus

Abstract

A charge roller includes, in a surface thereof, recesses that have sizes that are equivalent to or larger than a volume average particle diameter of a toner accommodated in a developing unit and that are capable of collecting the toner retransferred to a photosensitive drum.

Claims

1. An image forming apparatus comprising:

a movable belt;

a first image bearing member that abuts against the belt and that carries a toner image, a first transfer portion being formed at a position where the first image bearing member and the belt abut against each other;

a second image bearing member that is disposed downstream of the first image bearing member in a moving direction of the belt and that carries a toner image having a color different from the toner image carried on the first image bearing member, a second transfer portion being formed at a position where the second image bearing member and the belt abut against each other;

a developing member that develops an electrostatic latent image formed on the second image bearing member with toner into a toner image, the developing member being capable of collecting toner that is charged to a first polarity that is a normal charge polarity of the toner and that has remained on the second image bearing member after the toner has passed through the second transfer portion with a rotation of the second image bearing member; and

a charge member that charges the second image bearing member, the charge member including, in a surface thereof, recesses that have sizes that are equivalent to or larger than a volume average particle diameter of the toner accommodated on the developing member, the recesses being capable of collecting toner that has born on the belt after transferring toner to the first image bearing member at the first transfer portion and moved to the second image bearing member from the belt at the second transfer portion.

2. The image forming apparatus according to claim 1, further comprising:

a power supply that applies a voltage having a first polarity to the charge member,

wherein a voltage having a first polarity is applied from the power supply to the charge member so that the charge member, while charging the second image bearing member, collects the toner that has moved to the second image bearing member at the second transfer portion after being transferred at the first transfer portion from the first image bearing member.

3. The image forming apparatus according to claim 2, further comprising:

a first transfer member disposed so as to correspond to the first image bearing member and opposite the first image bearing member with the belt interposed therebetween, the first transfer member biasing the belt towards the first image bearing member to form the first transfer portion;

a second transfer member disposed so as to correspond to the second image bearing member and opposite the second image bearing member with the belt interposed therebetween, the second transfer member biasing the belt towards the second image bearing member to form the second transfer portion; and

a transfer power supply that applies a voltage to the second transfer member,

wherein an electric field in a direction in which the toner having the first polarity moves from the second image bearing member towards the belt is formed at the second transfer portion by applying, from the transfer power supply to the second transfer member, a voltage having a second polarity that is a polarity that is inverted with respect to the first polarity.

4. The image forming apparatus according to claim 3,

wherein in the toner transferred from the first image bearing member at the first transfer portion, toner charged to a second polarity by receiving an electric discharge generated at the second transfer portion in a state in which a voltage of the second polarity has been applied to the second transfer member from the transfer power supply is collected by the charge member after moving to the second image bearing member at the second transfer portion.

5. The image forming apparatus according to claim 4, further comprising:

a collecting member that collects toner that has moved to the belt,

wherein the developing member includes a developing member that is capable of abutting against and separating from the second image bearing member, and

wherein during a non-image-forming period in which a toner image is not formed on the second image bearing member and in a state in which the developing member is separated from the second image bearing member, the collecting member collects toner that has been charged to the second polarity and that has moved from the second image bearing member to the belt at the second transfer portion after being moved from the charge member to the second image bearing member.

6. The image forming apparatus according to claim 5,

wherein by applying a voltage having the first polarity from the transfer power supply to the second transfer member, the toner that has been moved from the charge member to the second image bearing member is moved from the second image bearing member to the belt at the second transfer portion.

7. The image forming apparatus according to claim 1,

wherein a contact member that abuts against the second image bearing member at a portion between the second image bearing member and a position where the charge member and the second image bearing member are in contact with each other in a rotation direction of the second image bearing member is not provided.

8. The image forming apparatus according to claim 1,

wherein the charge member is a roller member including an elastic layer in which a surface of the elastic layer includes spherical particles having sizes equivalent to or larger than the volume average particle diameter of the toner.

9. The image forming apparatus according to claim 8,

wherein the spherical particles are insulating resin particles.

10. The image forming apparatus according to claim 1,

wherein the charge member is a roller member including an elastic layer in which spaces having sizes that are equivalent to or larger than the volume average particle diameter of the toner are formed in a surface of the elastic layer by expansion of thermally expandable micro capsule particles.

11. The image forming apparatus according to claim 1,

wherein the belt is an intermediate transfer belt, and

wherein a toner images carried on the first image bearing member and the second image bearing member are secondarily transferred from the intermediate transfer belt to a transfer material after being primarily transferred from the first image bearing member and the second image bearing member to the intermediate transfer belt.

12. The image forming apparatus according to claim 11, further comprising:

a secondary transfer member that abuts against an outer peripheral surface of the intermediate transfer belt; and

a transfer power supply that applies a voltage to the secondary transfer member,

wherein by forming a charged potential on the intermediate transfer belt by applying a voltage from the transfer power supply to the secondary transfer member, toner images are primarily transferred from the first transfer portion and the second transfer portion to the intermediate transfer belt, and the toner images are secondarily transferred from the intermediate transfer belt to a transfer material at a position where the secondary transfer member and the intermediate transfer belt abut against each other.

13. The image forming apparatus according to claim 1,

wherein the belt is a conveying belt that conveys a transfer material, and

wherein toner images carried on the first image bearing member and the second image bearing member are sequentially transferred in an overlapping manner to a transfer material conveyed by the conveying belt.

14. The image forming apparatus according to claim 1,

wherein a reduced peak height Rpk and a core roughness depth Rk obtained by measuring a surface profile of the charge member in accordance with MS B0671-2:

2002 with a surface roughness tester complying with MS B0671-2;

2002, and a volume average particle diameter of the toner D satisfy the following Math 1,

Rpk+Rk≥

D 

 

(Math

     1).