Bar code scanner with dc brushless motor

Abstract

A laser scanner having a rotating mirror, such as a POS scanner as used in supermarkets, uses a closed-loop velocity controlled DC brushless motor for rotating the mirror. In addition to providing a hall effect motor speed signal which is used for monitoring and safety features in association with the scanner, the DC brushless motor provides the advantages of greatly reduced power consumption, decreased temperature rise, less electrical noise in the analog scanner circuitry, reduced cost, and greatly reduced size, sometimes over 80%. The use of the inherent motor speed signal from the DC brushless motor also enables elimination of costly mechanical windswitches as typically used in prior scanners.