Belt fuser overheat control

Details Belt fuser overheat control Belt fuser overheat control

2000-09-01

2001-09-04

Pendegrass, Joan (Department: 2852)

Electrophotography

Control of electrophotography process

Responsive to copy media characteristic

C399S068000

Reexamination Certificate

active

06285838

ABSTRACT:

TECHNICAL FIELD
This invention relates to imaging apparatus employing heaters, specifically heaters having belt-fuser characteristics, to fix a toned image to paper or other substrate. More specifically, this invention relates to maintaining high throughput while protecting such apparatus from overheating when the substrate is narrow.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,325,166 to Hamilton et al. teaches assigning weighted values to sheets of different characteristics specifically the values of −7 for full size sheets, +13 for narrower sheets such as A5, and +17 for envelopes. These weighted values are accumulated as a count. When the count reaches a predetermined value, the time interval between subsequent sheets is increased. Subsequent feeding of full size sheets reduces the count to a second predetermined value at which normal throughput is resumed, although the second predetermined value is more than zero, so reduced throughput may be again resumed from feeding less sheets through from a cold condition.
The implementation of the foregoing patent was directed to nip fusers, which employ two rollers in nip relation through which the sheet passes for fusing. A belt fuser employs a thin belt wrapped over a ceramic or other low-thermal-capacity heater. A representative belt fuser is disclosed in U.S. Pat. No. 5,860,051 to Goto et al. The thin belt of a belt fuser is highly susceptible to damage from fusing sheets which extend only partly across the width of the belt, i.e., narrow media. The differential in heat across the belt is the source of overheat damage. Conversely, a belt fuser recovers more quickly from the differential in heat when no sheet is in the fuser, such as during the interpage time interval. This is particularly true where the heater is not powered during some of that time interval. The term “belt fuser characteristics” refers to a fuser having low thermal capacity, preferably one, which is routinely not powered during part of interpage time intervals.
To maintain good throughput (number of sheets per unit of time) while protecting the fuser, both width and length are determined and employed as described below.
DISCLOSURE OF THE INVENTION
Both a width category and a length category of sheets being sent to the fuser are determined. A weighted value for each sheet is assigned which is larger for smaller widths and larger for longer lengths. For standard width media, a weighted value is assigned which is opposited in sense (i.e., narrow media assigned plus weighted values, wide media assigned minus weighted values). As sheets are fed these weighted values are accumulated in a first count.
Upon the first count reaching a predetermined plus value, media speed is reduced, fuser temperature is reduced and the intermedia time interval is reduced. Also, upon the first count reaching the predetermined value, a second count of weighted values of sheets fed is begun. The weighted values usually will be different from the weighted values used in the first count, but will be in the same sense and in similar proportion to one another. At certain predetermined values of the second count, depending on the type of media, the interval between sheets is increased. In an embodiment, narrow but short media is not additionally delayed, while narrow but somewhat longer media is delayed from 15 ppm to 9 ppm, while more stressful media is delayed at one value of the second count from 15 ppm to 7 ppm and at a higher value of the second count from 7 ppm to 6 ppm.
Both the first count and the second count do not rise after reaching their predetermined value for the last feeding action as described. When the second count is reduced by the feeding of a standard sheet, the first count is reduced with it to an intermediate, predetermined value so as to avoid frequent oscillations between full speed and half speed.
Various media types given different weighting and feeding categories are paper, envelopes and labels. Labels are typically very thick, at least when they have a layer over an adhesive surface


REFERENCES:
patent: 4549803 (1985-10-01), Ohno et al.
patent: 4595279 (1986-06-01), Kuru et al.
patent: 4634262 (1987-01-01), Imaizumi et al.
patent: 4825242 (1989-04-01), Elter
patent: 5170215 (1992-12-01), Pfeuffer
patent: 5289247 (1994-02-01), Takano et al.
patent: 5325166 (1994-06-01), Hamilton et al.
patent: 5436709 (1995-07-01), Sakaizawa et al.
patent: 5552874 (1996-09-01), Ohtsuka et al.
patent: 5563696 (1996-10-01), Futagawa et al.
patent: 5568229 (1996-10-01), Szlucha
patent: 5669039 (1997-09-01), Ohtsuka et al.
patent: 5689760 (1997-11-01), Suzuki et al.
patent: 5860051 (1999-01-01), Goto et al.
patent: 5978612 (1999-11-01), Suzuki et al.

Affiliated with

Also associated with

Rating

Belt fuser overheat control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Belt fuser overheat control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Belt fuser overheat control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2541878