IMAGE FORMING APPARATUS

• US 20100239335A1
• Filed: 03/16/2010
• Published: 09/23/2010
• Est. Priority Date: 03/17/2009
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: SAWAI, Yuuji
• Granted Patent: US 8,682,236 B2
• Time in Patent Office: Days
• US Class Current: 399/319
• 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 2215/0129 horizontal medium transport path at the secondary transfer

Abstract

An image forming apparatus includes a first endless transfer belt, first extending members, a first transfer electric generator, a secondary transfer unit disposed outboard and at least partially facing the first endless transfer belt, and an ultrasonic vibration generator, including a vibration imparting part from which ultrasonic vibrations is applied to the first endless transfer belt. The secondary transfer unit and the first endless transfer belt form a transfer nip forming a transfer electric field due to a difference in electric potential therebetween. The first transfer electric field generator contacts the first endless transfer belt at a position other than a position disposed opposite the secondary transfer unit. The vibration imparting part contacts the first endless transfer belt at a position intermediate between the first transfer electric field generator and the secondary transfer unit in a direction of rotation of the first endless transfer belt.

Claims

1. An image forming apparatus, comprising:

a first endless transfer belt to carry a toner image thereon after a primary image transfer operation onto a surface thereof during rotation of the first endless transfer belt;

first extension members around which the first endless transfer belt is extended;

a first transfer electric field generator disposed inboard of the first endless transfer belt;

a secondary transfer unit disposed outboard of and at least partially facing the first endless transfer belt to transfer the toner image onto a transfer medium conveyed by the secondary transfer unit; and

an ultrasonic vibration generator to generate ultrasonic vibrations, disposed inboard of the first endless transfer belt and comprising a vibration imparting part from which the ultrasonic vibrations are applied to an inner face of the first endless transfer belt,

the secondary transfer unit disposed facing and in contact with a first surface portion of the first endless transfer belt to form a transfer nip therebetween, through which the transfer medium is conveyed when the toner image is transferred onto the transfer medium in a secondary image transfer operation,

the transfer nip forming a transfer electric field due to a difference in electric potential between the first endless transfer belt and the secondary transfer unit,

the first transfer electric field generator contacting the inner face of the first surface portion of the first endless transfer belt in the transfer nip and pressing against the first endless transfer belt at a position along the first endless transfer belt in the transfer nip other than a position disposed opposite the secondary transfer unit with the first endless transfer belt interposed therebetween,

the vibration imparting part of the ultrasonic vibration generator contacting the first endless transfer belt at a position intermediate between the first transfer electric field generator and the secondary transfer unit in a direction of rotation of the first endless transfer belt.

2. The image forming apparatus according to claim 1, wherein the secondary transfer unit includes a secondary transfer roller that contacts the first endless transfer belt directly to form the transfer nip therebetween to perform the secondary image transfer operation.

3. The image forming apparatus according to claim 2, wherein at least one of the first extension members around which the first endless transfer belt is extended constitutes the first transfer electric field generator forming multiple first transfer electric field generators,

the secondary transfer roller being disposed at a position intermediate between the multiple first transfer electric field generators in a direction of rotation of the first endless transfer belt.

4. The image forming apparatus according to claim 2, wherein the ultrasonic vibration imparting part of the ultrasonic vibration generator is disposed at a position upstream from the secondary transfer roller in a direction of rotation of the first endless transfer belt and contacts the inner face of the first endless transfer belt in the transfer nip.

5. The image forming apparatus according to claim 2, wherein the ultrasonic vibration imparting part of the ultrasonic vibration generator is disposed between one of the multiple first transfer electric field generators and the secondary transfer roller.

6. The image forming apparatus according to claim 1, wherein the secondary transfer unit comprises

a second endless transfer belt;

second extending members around which the second endless transfer belt is extended to define multiple extended surface portions therebetween including a second surface portion; and

a second transfer electric field generator disposed facing and in contact with an inner face of the second endless transfer belt in the transfer nip to contact the first endless transfer belt via the second endless transfer belt,

the first extended surface portion of the first endless transfer belt and the second extended surface portion of the second endless transfer belt forming the transfer nip.

7. The image forming apparatus according to claim 6, wherein at least one of the first extension members around which the first endless transfer belt is extended constitutes the first transfer electric field generator forming multiple first transfer electric field generators,

the secondary transfer electric field generator being disposed at a position intermediate between the multiple first transfer electric field generators in a direction of rotation of the first endless transfer belt.

8. The image forming apparatus according to claim 6, wherein the ultrasonic vibration imparting part of the ultrasonic vibration generator is disposed upstream from the second transfer electric field generator in a direction of rotation of the first endless transfer belt and contacts the inner face of the first endless transfer belt.

9. The image forming apparatus according to claim 6, wherein the ultrasonic vibration imparting part of the ultrasonic vibration generator is disposed between one of the multiple first transfer electric field generators and the secondary transfer electric field generator.

10. The image forming apparatus according to claim 6, wherein the second extending members that extend the second endless transfer belt serve as a driven roller,

a transfer electric field being formed in a vicinity of an entrance of the transfer nip in the direction of rotation of the first endless transfer roller to attract the toner image carried on the surface of the first endless transfer belt and the second endless transfer belt to the first endless transfer belt.

11. The image forming apparatus according to claim 10, wherein one of the first extending members extends the first endless transfer belt at an upstream end of the first extended surface portion and serves as a first upstream roller and one of the second extending members extends the second endless transfer belt at an upstream end of the second extended surface portion and serves as a second upstream roller,

a difference in electric potential between the first upstream roller and the second upstream roller attracting the toner image carried on the first endless transfer belt and the second endless transfer belt to the first endless transfer belt.

12. The image forming apparatus according to claim 1, further comprising multiple first transfer electric field generators including the first transfer electric field generator,

the vibration imparting part of the ultrasonic vibration generator contacting the first endless transfer belt between two adjacent first transfer electric field generators of the multiple first transfer electric field generators that contact the first endless transfer belt.

13. The image forming apparatus according to claim 12, wherein the secondary transfer unit includes a second transfer electric field generator to contact the first endless transfer belt between the two adjacent first transfer electric field generators.

14. The image forming apparatus according to claim 13, wherein the vibration imparting part of the ultrasonic vibration generator contacts the first endless transfer belt at a position upstream of the second transfer electric field generator in the direction of rotation of the first endless transfer belt.

15. The image forming apparatus according to claim 1, wherein at least one of a surface resistivity of an outer surface and a surface resistivity of an inner surface of the first endless transfer belt falls within a range of from 1×

10⁹ [Ω

/sguare] to 1×

10¹² [Ω

/sguare].

16. The image forming apparatus according to claim 1, wherein the transfer nip transfers the toner image held on the first endless transfer belt onto a recording medium.