ABSTRACT
This chapter updates and expands upon the material covered by Gerald A. Rynkowski in Optical Scanning, with greater emphasis being placed on brushless DC motors and the associated control electronics designed specifically for rotary scanning applications. It explores the trends in motor and control technologies that are being utilized in polygonal scanners through the discussion of specific applications. The difficult rotor mechanical stability requirements for high-speed scanner operation are easily achieved with the use of a hysteresis synchronous motor. A brushless DC motor duplicates the performance characteristics of a DC motor only when its windings are properly commutated, which means that the winding currents are applied at the proper time, polarity, and in the correct order. The basic control requirements for a precision polygonal spinner are to provide synchronization and velocity control for precise scan registration, whether on a film plane or detector array, or at a distant target being illuminated.
