Fixing device for copying machine

• US 4,714,427 A
• Filed: 04/06/1987
• Issued: 12/22/1987
• Est. Priority Date: 04/26/1985
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Tsuruoka, Ichiro, Takahashi, Mitsuru
• Primary Examiner(s): Yuen, Henry C.
• Application Number:
  US07/036,128
• Time in Patent Office: 260 Days
• Field of Search: 432/59, 432/60, 432/8, 219/216, 219/469, 34/95
• US Class Current: 432/59
• CPC Class Codes: G03G 15/2064 combined with pressure

Abstract

One or two auxiliary rollers of relatively small diameter are pressed against the peripheral surface of a main rotatable body which is heated. Where the two auxiliary rollers are employed, they are spaced apart from each other and are rotated in one direction at the same peripheral speed as that of the main rotatable body. A sheet carrying an unfixed toner image is fed by being gripped between the main rotatable body and the auxiliary rollers, during which the toner is heated and dried, and fixed to the sheet with the solvent evaporated. Thereafter, the sheet is discharged toward a next process. The sheet auxiliary sheets are relatively disposed under certain positional conditions for keeping the sheet in intimate contact with the main rotatable body to achieve proper toner fixing and sheet feeding operations.

Claims

1. A fixing device for use in a wet-type copying machine, comprising:

a main rotatable body;

means for heating said main rotatable body; and

means for holding a sheet, which has a front side and a back side and carries on its front side a wet-type unfixed toner image, against said main rotatable body as heated by said heating means over a predetermined interval on the main rotatable body to allow the toner image to be fixed to the sheet and also to allow the sheet to be fed by said main rotatable body;

wherein;

the back side of said sheet makes contact with the main rotatable body while the front side, which carries said wet-type unfixed toner image, faces away from the main rotatable body and makes contact with said means for holding;

the surface of the main rotatable body which makes contact with the back side of the sheet is smooth; and

the surface of the means for holding which makes contact with the front side of the sheet has a multiplicity of fine projections;

said holding means comprises an auxiliary roller adjacent to said main rotatable body for concurrent rotation therewith so that portions of said auxiliary roller and said main rotatable body will move in one direction, said main rotatable body and said auxiliary roller being capable of feeding a sheet held therebetween;

said main rotatable body comprises a main roller heated by said heating means; and

said auxiliary roller comprises at least two auxiliary rollers spaced from each other, said main roller and adjacent ones of said auxiliary rollers being relatively positioned such that an angle formed between a first line tangential to both said main roller and an upstream one of said adjacent auxiliary rollers in the direction of feed of the sheet and a second line tangential to the downstream auxiliary roller at point where said first line intersects the peripheral surface of said downstream auxiliary roller is an obtuse angle.

2. A fixing device according to claim 1, further including a sheet separator disposed downstream of said auxiliary roller in the direction in which said main roller rotates, said sheet separator being held against the peripheral surface of said main roller.

3. A fixing device according to claim 1, wherein said auxiliary roller comprises two auxiliary rollers, the downstream auxiliary roller being larger in diameter than the upstream auxiliary roller.

4. A fixing device according to claim 1, further including a fan for applying hot air against the sheet having passed between said main roller and said auxiliary rollers.

5. A fixing device according to claim 4, further including an air deflector disposed below said fan for changing the direction of hot air applied by said fan.

6. A fixing device as in claim 1 in which said fine projections on the surface of the means for holding have areas of at most 50×

50 microns.