Belt fuser overheat control

Abstract

To protect a belt fuser (,) a weighted value for sheets being fused is assigned which is larger for smaller widths and larger for longer length. For standard width media a negative value is assigned. A first count is maintained until it reaches a first threshold, after which (operations,and,), the printer is slowed to half speed, twice interpage gap interval and lower fuser temperature. A subsequent count is made of a second set of weighted values (action,). In response to the second count the interpage gap interval is increased depending on the size of the count and the nature of the media. For example (Table 1), narrow and long media is fed 2 sheets at 30 ppm, then 3 sheets at 15 ppm by slowdown, then 5 sheets at 9 ppm by increasing the gap interval during slowdown and the remainder of such sheets are fed at 5 ppm by further increasing the gap interval. Very short envelopes and paper are fed 10 sheets at 10 ppm and the rest at 15 ppm by the slowdown. As count 1 is reduced, it must be at an intermediate value before ending the slowdown, which avoids excess switching between full speed and half speed. This operates the belt fuser at temperatures avoiding damage from narrow media while throughput is good.