| 摘要 |
A control system for a scanning motor that may operate at constant power, which has a control circuit including an H-Bridge (14) connected across the drive coil (12) of the motor (13). The control circuit operates under microprocessor (16) control for digitally generating selected high current and a low current thresholds, which can be changed to enable the scanning motor to be operative over a large range (e.g. 3.3v to 8v) of supply voltage and to control the arc over which the motor oscillates and, therefore, the scan angle of an optical beam which scans a bar code. The control circuit turns the current to the drive coil on and off when the high and low thresholds are reached thereby varying the current which the motor draws which determines the scan angle and scan rate and average current draw, which may be maintained constant for constant power consumption.
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