Registers – Coded record sensors – Particular sensor structure
Patent
1992-06-26
1994-01-18
Hajec, Donald
Registers
Coded record sensors
Particular sensor structure
359199, 318286, G06K 710
Patent
active
052801632
ABSTRACT:
A drive circuit for a bar code scanner for driving an oscillatory resonant motor therein which periodically oscillates in opposite rotary directions to impart an oscillatory motion to a scanning mirror of the bar code scanner. In the disclosed drive arrangement, the motor is driven at its own natural resonant frequency, which requires very little current to maintain the oscillatory motion. A scanning beam is directed against the oscillating scanning mirror, which causes the beam to be periodically scanned across a field of view of the bar code scanner. A detector detects reflections of the scanned beam, as by a bar code symbol being scanned, and generates an output signal representative thereof. The resonant motor, having a rotor with a permanent magnet mounted thereon, drives the scanning mirror, and includes a drive winding positioned adjacent to the permanent magnet for applying a driving force thereto only in a first rotary direction, and a feedback winding also positioned adjacent to the permanent magnet for deriving a substantially sinusoidal feedback voltage as the permanent magnet periodically passes in opposite directions by the feedback winding. A drive circuit for the resonant motor includes a drive amplifier coupled to the feedback winding which is turned on only by positive halves of the feedback voltage. A driver transistor is coupled between the drive amplifier and the drive winding to drive the motor only during positive halves of the feedback voltage. A return biasing spring drives the rotor in the second rotary direction.
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Hajec Donald
Symbol Technologies Inc.
Young Adrian
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