NIP formation assembly, fixing device, and image forming apparatus

Patent metadata

Field	Value
Publication number	US-9618886-B2
Application number	US-201514979686-A
Country	US
Kind code	B2
Filing date	Dec 28, 2015
Priority date	Dec 26, 2014
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A nip formation assembly disposed opposite an opposed rotator via an endless belt includes a nip formation pad to press against the opposed rotator via the endless belt to form a fixing nip between the endless belt and the opposed rotator, through which a recording medium bearing a toner image is conveyed. A fixing heater is disposed opposite at least a center span of the endless belt in an axial direction thereof where the recording medium is conveyed. The fixing heater heats the endless belt. A lateral end heater is mounted on the nip formation pad and disposed opposite a lateral end span of an inner circumferential surface of the endless belt in the axial direction thereof. The lateral end heater heats the endless belt.

First claim

What is claimed is:

1. A nip formation assembly disposed opposite an opposed rotator via an endless belt, the nip formation assembly comprising:
a nip formation pad to press against the opposed rotator via the endless belt to form a fixing nip between the endless belt and the opposed rotator, the fixing nip through which a recording medium bearing a toner image is conveyed;
at least one fixing heater disposed opposite at least a center span of the endless belt in an axial direction thereof where the recording medium is conveyed, the fixing heater to heat the endless belt; and
a lateral end heater mounted on the nip formation pad and disposed opposite a lateral end span of an inner circumferential surface of the endless belt in the axial direction thereof, the lateral end heater to heat the endless belt, wherein
the fixing heater and the lateral end heater are separated in a pressurization direction in which the nip formation pad presses against the opposed rotator.

2. The nip formation assembly according to claim 1 ,
wherein the nip formation pad includes a nip formation face contacting the inner circumferential surface of the endless belt, and
wherein the lateral end heater includes an endless belt side face disposed opposite the inner circumferential surface of the endless belt, the endless belt side face being leveled with the nip formation face of the nip formation pad in the pressurization direction in which the nip formation pad presses against the opposed rotator.

3. The nip formation assembly according to claim 2 , further comprising another lateral end heater mounted on the nip formation pad and disposed opposite another lateral end span of the inner circumferential surface of the endless belt in the axial direction thereof, the another lateral end heater to heat the endless belt,
wherein the nip formation face is sandwiched between the lateral end heater and the another lateral end heater in the axial direction of the endless belt.

4. The nip formation assembly according to claim 2 , further comprising a slide sheet sandwiched between the inner circumferential surface of the endless belt and the nip formation face of the nip formation pad.

5. The nip formation assembly according to claim 2 , wherein the endless belt side face of the lateral end heater contacts the inner circumferential surface of the endless belt and defines an extension of the nip formation face of the nip formation pad in the axial direction of the endless belt.

6. The nip formation assembly according to claim 2 , wherein the endless belt side face of the lateral end heater is leveled with the nip formation face of the nip formation pad in the pressurization direction while the nip formation pad forms the fixing nip.

7. The nip formation assembly according to claim 1 , wherein the nip formation pad includes a recess mounting the lateral end heater.

8. The nip formation assembly according to claim 7 , further comprising a deformable elastic member supporting the lateral end heater and disposed in the recess, the elastic member being deformed as the nip formation pad presses the elastic member against the endless belt via the lateral end heater.

9. The nip formation assembly according to claim 1 , wherein the lateral end heater partially overlaps the fixing heater in the axial direction of the endless belt.

10. The nip formation assembly according to claim 1 , wherein the lateral end heater partially overlaps an outboard span of the fixing heater in the axial direction of the endless belt, and the outboard span is where a light distribution radiated from the fixing heater has a decreased density.

11. A fixing device comprising:
an endless belt rotatable in a predetermined direction of rotation;
an opposed rotator disposed opposite the endless belt;
a nip formation pad to press against the opposed rotator via the endless belt to form a fixing nip between the endless belt and the opposed rotator, the fixing nip through which a recording medium bearing a toner image is conveyed;
a fixing heater disposed opposite at least a center span of the endless belt in an axial direction thereof where the recording medium is conveyed, the fixing heater to heat the endless belt; and
a lateral end heater mounted on the nip formation pad and disposed opposite a lateral end span of an inner circumferential surface of the endless belt in the axial direction thereof, the lateral end heater to heat the endless belt, wherein
the fixing heater and the lateral end heater are separated in a pressurization direction in which the nip formation pad presses against the opposed rotator.

12. The fixing device according to claim 11 ,
wherein the nip formation pad includes a nip formation face contacting the inner circumferential surface of the endless belt, and
wherein the lateral end heater includes an endless belt side face disposed opposite the inner circumferential surface of the endless belt, the endless belt side face being leveled with the nip formation face of the nip formation pad in the pressurization direction in which the nip formation pad presses against the opposed rotator.

13. The fixing device according to claim 12 , wherein the endless belt side face of the lateral end heater is leveled with the nip formation face of the nip formation pad in the pressurization direction while the nip formation pad forms the fixing nip.

14. The fixing device according to claim 12 , further comprising another lateral end heater mounted on the nip formation pad and disposed opposite another lateral end span of the inner circumferential surface of the endless belt in the axial direction thereof, the another lateral end heater to heat the endless belt,
wherein the nip formation face is sandwiched between the lateral end heater and the another lateral end heater in the axial direction of the endless belt.

15. The fixing device according to claim 12 , further comprising a slide sheet sandwiched between the inner circumferential surface of the endless belt and the nip formation face of the nip formation pad.

16. The fixing device according to claim 12 , wherein the endless belt side face of the lateral end heater contacts the inner circumferential surface of the endless belt and defines an extension of the nip formation face of the nip formation pad in the axial direction of the endless belt.

17. An image forming apparatus comprising:
an image bearer to bear a toner image; and
a fixing device disposed downstream from the image bearer in a recording medium conveyance direction to fix the toner image on a recording medium,
the fixing device including:
an endless belt rotatable in a predetermined direction of rotation;
an opposed rotator disposed opposite the endless belt;
a nip formation pad to press against the opposed rotator via the endless belt to form a fixing nip between the endless belt and the opposed rotator, the fixing nip through which the recording medium bearing the toner image is conveyed;
a fixing heater disposed opposite at least a center span of the endless belt in an axial direction thereof where the recording medium is conveyed, the fixing heater to heat the endless belt;
a lateral end heater mounted on the nip formation pad and disposed opposite a lateral end span of an inner circumferential surface of the endless belt in the axial direction thereof, the lateral end heater to heat the endless belt; and
an electric circuit to selectively energize the fixing heater and the lateral end heater, wherein
the fixing heater and the lateral end heater are separated in a pressurization direction in which the

Assignees

• Seto Takashi
• Ishii Kenji
• Kishi Kazuhito
• Fujimoto Ippei
• Seki Takayuki
• Matsusaka Susumu
• Ogino Yasuhiko
• Kobashigawa Shohta
• Takagi Hiromasa
• Ricoh Co Ltd

Inventors

• Seto Takashi
• Ishii Kenji
• Kishi Kazuhito
• Fujimoto Ippei
• Seki Takayuki
• Matsusaka Susumu
• Ogino Yasuhiko
• Kobashigawa Shohta
• Takagi Hiromasa

Classifications

• G03G2215/2035

  the fixing nip having a stationary belt support member opposing a pressure member · CPC title

• G03G15/2053 Primary

  Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating · CPC title

• G03G15/2042

  specially for the axial heat partition · CPC title

• G03G2215/0132

  vertical medium transport path at the secondary transfer · CPC title

• G03G15/2082

  Physics · mapped topic