Resonant motor driver system for data reading
AssigneePSC Scanning, Inc.
InventorsJames E. Colley, Edward P. Coleman
Life of this patent
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Abstract
A method for driving a resonant electromagnetically-actuated motor, such as those used to scan a light source for date reading applications, wherein drive current is applied when the back-EMF induced in the actuator coil is zero and has a specific slope, and that drive current is removed after the induced back-EMF voltage has changed by a predetermined constant value. The drive circuit will drive the motor across a scan angle which remains substantially constant regardless of changes in ambient temperature, changes in motor orientation, or externally applied forces.
Claims43
A method of driving a resonant scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- dithering the spring-mounted dither element over a scan cycle by applying a drive current pulse at spaced intervals;
- determining velocity of the scan mechanism;
- selecting a start point for the drive current pulse corresponding to a zero velocity point for the velocity of the scan mechanism;
- applying the drive current pulse at the start point;
- discontinuing the drive current pulse within one quarter of a scan cycle when the velocity of the scan mechanism has increased to a predetermined velocity over zero velocity and below peak motor velocity.
A method of driving a resonant scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- dithering the spring-mounted dither element by applying a drive current pulse at spaced intervals;
- determining velocity of the scan mechanism;
- selecting a start point for the drive current pulse corresponding to a zero velocity point for the velocity of the scan mechanism;
- applying the drive current pulse at the start point;
- discontinuing the drive current pulse when the velocity of the scan mechanism has changed by a given amount,
- wherein the step of determining velocity of the scan mechanism comprises measuring a back-EMF voltage on a drive coil of the drive motor,
- wherein the step of discontinuing the drive current pulse comprises discontinuing when change in the back-EMF voltage exceeds a given amount ΔV1.
A scan drive mechanism comprising
- a spring-mounted dither element;
- a magnetic drive motor including a drive coil for driving the dither element in an oscillatory manner over a scan cycle;
- a drive circuit for (a) applying a drive current pulse to the drive coil at a given start point near a zero velocity point of the drive motor and (b) discontinuing the drive current pulse within one quarter of a scan cycle once velocity of the drive motor has increased to a given velocity over zero velocity and below peak motor velocity.
A scan drive mechanism comprising
- a spring-mounted dither element;
- a magnetic drive motor including a drive coil for driving the dither element in an oscillatory manner;
- a drive circuit for (a) applying a drive current pulse to the drive coil at a given start point near a zero velocity point of the drive motor and (b) discontinuing the drive current pulse once velocity of the drive motor is determined to have increased by a given amount,
- wherein the given start point precedes a zero velocity point by no more than 10% of a peak velocity of the drive motor.
A method of driving a scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- dithering the spring-mounted dither element over a scan cycle by applying a drive current pulse;
- determining velocity of the scan mechanism;
- selecting a start point for the drive current pulse corresponding a point near where the scan mechanism is at zero velocity;
- applying the drive current pulse at the start point;
- discontinuing the drive current pulse within one quarter of a scan cycle when the velocity of the scan mechanism has increased to a predetermined velocity over zero velocity and below peak motor velocity.
A method of driving a scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- dithering the spring-mounted dither element by applying a drive current pulse;
- determining velocity of the scan mechanism;
- selecting a start point for the drive current pulse corresponding a point near where the scan mechanism is at zero velocity;
- applying the drive current pulse at the start point;
- discontinuing the drive current pulse when the velocity of the scan mechanism has changed by a given amount;
- selecting the start point for the drive current pulse at a point preceding the zero velocity point by no more than 10% of a peak velocity of the drive motor.
A method of driving a scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- periodically applying once per dither cycle a first drive current pulse to drive the drive motor in one direction;
- monitoring velocity of the scan mechanism over the dither cycle;
- selecting a start point for the first drive current pulse near a zero velocity point and commencing the first drive current pulse at the start point;
- controlling scan angle over which the scan mechanism dithers by discontinuing the first drive current pulse within one quarter of a scan cycle when the velocity of the scan mechanism has increased to a predetermined velocity which is greater than zero velocity and below peak motor velocity.
A method of driving a scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- periodically applying once per dither cycle a first drive current pulse to drive the drive motor in one direction;
- monitoring velocity of the scan mechanism over the dither cycle;
- selecting a start point for the first drive current pulse near a zero velocity point and commencing the first drive current pulse at the start point;
- controlling scan angle over which the scan mechanism dithers by discontinuing the drive pulse when the velocity of the scan mechanism has increased to a predetermined velocity which is greater than zero velocity and below peak motor velocity;
- selecting an initial setting for the predetermined velocity corresponding to an arbitrary velocity setting and then adjusting the predetermined velocity up or down until a desired scan angle is achieved.
A method of driving a scan mechanism, the scan mechanism including a spring-mounted dither element and a drive motor driven by a drive current, comprising the steps of
- periodically applying once per dither cycle a first drive current pulse to drive the drive motor in one direction;
- monitoring velocity of the scan mechanism over the dither cycle;
- selecting a start point for the first drive current pulse near a zero velocity point and commencing the first drive current pulse at the start point;
- controlling scan angle over which the scan mechanism dithers by discontinuing the drive pulse when the velocity of the scan mechanism has increased to a predetermined velocity which is greater than zero velocity and below peak motor velocity,
- wherein the step of discontinuing the drive current pulse comprises discontinuing when change in the back-EMF voltage exceeds a given amount ΔV1.
Dependencies are inferred from the claim text.