Heated fuser roller

Details Heated fuser roller Heated fuser roller

2000-06-26

2001-05-22

Royer, William J. (Department: 2852)

Electrophotography

Image formation

Fixing

C219S216000, C219S469000, C219S470000, C399S331000, C399S333000

Reexamination Certificate

active

06236830

ABSTRACT:

FIELD OF THE INVENTION
The invention relates generally to a fuser for use in an electrophotographic printing device and, more particularly, to a heated fuser roller.
BACKGROUND OF THE INVENTION
In electrophotographic printing devices, toner particles are used to form the desired image on the print medium, which is usually some type of paper. Once the toner is applied to the paper, the paper is advanced along the paper path to a fuser. In many printers, copiers and other electrophotographic printing devices, the fuser includes a heated fusing roller engaged by a mating pressure roller. As the paper passes between the rollers, toner is fused to the paper through a process of heat and pressure. A variety of different techniques have been developed to heat the fusing roller. One of the most common techniques for heating a fusing roller uses a quartz lamp placed inside the roller. The lamp is turned on to heat the fusing roller during printing. So called “instant-on” fusers were developed to reduce warm-up time, eliminate the need for standby power and improve print quality in single page or small print jobs. U.S. Pat. Nos. 5,659,867, 5,087,946, and 4,724,303 describe instant-on type fuser heaters that utilize a thin walled heated fusing roller. In the '867 patent, the heating element is a group of resistive conductors positioned on the surface of a thin walled ceramic tube. The conductors are overlaid with a glassy coating to provide a smooth exterior surface for the ceramic tube. In the '946 patent, the heating element is a conductive fiber filler material added to the plastic composition that forms the wall of the roller. In the '303 patent, the heating element is a resistance heating foil or printed circuit glued to the inside surface of the thin metal wall of the roller.
While these “instant-on” fuser heating techniques may be advantageous because the heating element is near the surface of the roller, substantial changes must be made to conventional fuser roller designs to incorporate both techniques. Hence, these techniques cannot be easily incorporated into the more common fuser roller designs. In addition, these techniques are all designed for hard walled fusing rollers, not for pressure rollers in general and not for the compliant pressure rollers used in many modern fusers.
SUMMARY OF THE INVENTION
The present invention is directed to a heated fuser roller that utilizes a series of heating wires in the outer layer of the roller. The invention was developed as a means to effectively heat the pressure roller in heated pressure fusers without requiring any major modifications or changes to the design of the fuser or the fuser rollers. The fuser roller includes an elongated roller and a plurality of heating wires extending axially through the roller. The heating wires are positioned near the surface of the roller. The heating wires may be embedded in the roller as an integrated component or the heating wires may be inserted into holes that extend axially through the rollers. In one preferred version of this embodiment of the invention, a voltage is applied from a power source to the heating wires through conductive disks mounted on each end of the roller. Each heating wire runs axially through the roller between the disks. A conductive wiper, shoe or other suitable contact device slides along each disk to maintain the electrical connection between the disks and the power source as the roller rotates.
The invention may also be embodied in a fuser that includes a pressure roller and a fusing roller. The heating wires are used to heat the pressure roller, the fusing roller, or both. In one preferred version of this embodiment, the fuser includes a conventional heated fusing roller and a heated pressure roller that engages the fusing roller during fusing operations. The heating element in the fusing roller is a quartz lamp. The heating element in the pressure roller includes a series of heating wires extending axially through the pressure roller near the surface of the roller.
“Heating wire” or “heating wires” as used in this Specification and in the claims refers generally to all types of elongated resistive conductors.


REFERENCES:
patent: 4377336 (1983-03-01), Parks et al.
patent: 4743940 (1988-05-01), Nagasaka et al.
patent: 4791275 (1988-12-01), Lee et al.
patent: 5241159 (1993-08-01), Chatteriee et al.
patent: 5773796 (1998-06-01), Singer et al.

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