Lexmark International, Inc.

Aaron Michael Lambert

Kevin Dean Schoedinger

Jason William Lawrence

Steven Michael Turney

David Ross Cutts

Ryan Matthew Smith

Christopher L Yaeger

An imaging device includes a fuser assembly including a heat transfer member and a backup member positioned to engage the heat transfer member thereby defining a fusing nip therewith. A motor is coupled to the backup member for rotating the backup member. A controller coupled to the fuser assembly controls the motor using time-based commutation for a period of time to rotate the backup member at a slower speed relative to a speed for performing a toner fusing operation. In memory, at least one lookup table is stored having entries which, when sequentially accessed by the controller during the time-based commutation, are used to generate one or more drive signals for the motor to cause current flowing through windings of the motor to have a substantially sinusoidal waveform.

Time-based commutation method and system for controlling a fuser assembly

In a laser printer, methods and apparatus include commutating a brushless dc motor having three windings. A controller receives discrete motor position signals, such as from hall-effect or FG sensors, and extrapolates motor position between the signals. It commutates the motor based on the extrapolated motor position and updates motor position whenever an actual discrete signal is received. Drive signals from the controller to the motor are such that a current flowing in any of the three windings follows a generally sinusoidal waveform. High and low switches are provided per each winding of the three windings and are cumulatively switched according to an extrapolated motor position based multiplier applied to a pulse width modulation duty cycle. In this regard, lookup tables, counters, registers and the like are provided. An engine card of the printer includes an ASIC with a power driver for use with generally off-the-shelf brushless dc motors.

Methods and apparatus for commutating a brushless DC motor in a laser printer

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Lexington, KY, United States of America

Aaron Michael Lambert