Granted Patent B2

US 6,849,833 · App. 10/365,789 · Granted Feb 1, 2005

Abstract

Claims (16)

1. A temperature control system for reducing flicker in an electrical resistance heater comprising:

an electrical resistance heater divided into at least two electrical loads and;

a source of electrical power for repetitively supplying electrical power to each of said at least two electrical loads at successive different time sub periods within a predetermined time period, wherein the sum of the power supplied to said at least two electrical loads is equal to the total power supplied to said electrical resistance heater during said predetermined time period; and wherein the power supplied to each electrical load is not supplied to each other electrical load within said predetermined time period.

2. The system of claim 1 wherein the power supplied during each time subperiod is proportional to its fraction of the total power supplied during said predetermined time period.

3. The system of claim 1 wherein the power supplied to each electrical load begins at or after power is supplied to each said other electrical load.

4. The system of claim 1 wherein the time subperiod during which power is supplied to each electrical load is out of phase with the time subperiod during which power is supplied to each other electrical load.

5. The system of claim 1 including logical control means for controlling the supply of power from said source of electrical power to said at least two electrical loads of said electrical resistance heater.

6. The system of claim 1 wherein said electrical resistance heater heats a rotating drum which contacts media for processing.

7. A temperature controlled electrically heated drum assembly having reduced flicker comprising:

a cylindrical drum rotatable on an axis, said drum having an outer surface divided into a plurality of zones arranged longitudinally along said axis of said drum;

a plurality of electrical resistance heaters, one for each of said plurality of zones, thermally coupled to each of said plurality of zones, respectively; and

a source of electrical power for repetitively supplying electrical power to each of said plurality of electrical resistance heaters at successive different time subperiods within a predetermined time period, wherein the sum of the power supplied to each said plurality of electrical resistance heaters is equal to the total power supplied during said predetermined time period; and wherein the power supplied to each electrical load is not supplied to each other electrical load within said predetermined period.

8. The drum assembly of claim 7 wherein the power supplied during each time subperiod is proportional to its fraction of the total power supplied during said predetermined time period.

9. The drum assembly of claim 7 wherein the power supplied to each of said plurality of electrical resistance heaters begins at or after power is supplied to another of said plurality of electrical resistance heaters.

10. The drum assembly of claim 7 wherein the time subperiod during which power is supplied to each of said plurality of electrical resistance heaters is out of phase with the time subperiod during which power is supplied to each other of said plurality of electrical resistance heaters.

11. The drum assembly of claim 7 including logical control means for controlling the supply of power from said source of electrical power to said plurality of electrical resistance heaters.

Assignments (15)