Method and apparatus for controlling mirror motion in light scanning arrangements
AssigneeSymbol Technologies, Inc.
InventorsJames Giebel, Peter Fazekas
Life of this patent
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Abstract
A method and apparatus of driving a motor in a light scanning arrangement. The method includes the following steps: (1) driving a drive coil with a drive signal to oscillate a scan mirror and a light beam reflected from the scan mirror; (2) generating a feedback signal having zero crossings during oscillation of the scan mirror by a feedback coil in proximity to the drive coil; (3) integrating the feedback signal to generate an integrated feedback signal; and (4) processing the integrated feedback signal to generate a periodic drive signal that has the same time period as the feedback signal.
Claims31
A motor drive circuit in a light scanning arrangement, comprising:
- a) a drive coil driven by a drive signal to oscillate a scan mirror and a light beam reflected from the scan mirror;
- b) a feedback coil for generating a feedback signal having zero crossings during oscillation of the scan mirror, the feedback coil being in proximity to the drive coil and being corrupted by cross-coupling between the coils at each zero crossing;
- c) circuitry for minimizing the cross-coupling at each zero crossing to generate an uncorrupted feedback signal;
- d) circuitry for integrating the uncorrupted feedback signal to generate an integrated feedback signal;
- and
- e) circuitry for processing the integrated feedback signal and the uncorrupted feedback signal to generate the drive signal as a square wave having vertical edges respectively corresponding to the zero crossings.
A method of driving a motor in a light scanning arrangement, comprising the steps of:
- a) driving a drive coil with a drive signal to oscillate a scan mirror and a light beam reflected from the scan mirror;
- b) generating a feedback signal having zero crossings during oscillation of the scan mirror by a feedback coil in proximity to the drive coil, the feedback coil being corrupted by cross-coupling between the coils at each zero crossing;
- c) minimizing the cross-coupling at each zero crossing to generate an uncorrupted feedback signal;
- d) integrating the uncorrupted feedback signal to generate an integrated feedback signal;
- and
- e) processing the integrated feedback signal and the uncorrupted feedback signal to generate the drive signal as a square wave having vertical edges respectively corresponding to the zero crossings.
A motor drive circuit in a light scanning arrangement, comprising:
- a) a drive coil driven by a drive signal to oscillate a scan mirror and a light beam reflected from the scan mirror;
- b) a feedback coil for generating a feedback signal having zero crossings during oscillation of the scan mirror, the feedback coil being in proximity to the drive coil;
- d) circuitry for integrating the feedback signal to generate an integrated feedback signal;
- and
- e) circuitry for processing the integrated feedback signal to generate a periodic drive signal that has the same time period as the feedback signal.
A method of driving a motor in a light scanning arrangement, comprising the steps of:
- a) driving a drive coil with a drive signal to oscillate a scan mirror and a light beam reflected from the scan mirror;
- b) generating a feedback signal having zero crossings during oscillation of the scan minor by a feedback coil in proximity to the drive coil;
- d) integrating the feedback signal to generate an integrated feedback signal;
- and
- e) processing the integrated feedback signal to generate a periodic drive signal that has the same time period as the feedback signal.
A scanner for reading indicia comprising:
- an oscillating mirror assembly having an magnet attached thereon;
- a drive coil for driving the magnet that controls the minor;
- a pickup coil for sensing the movement of the magnet;
- and
- wherein the output of the pickup coil is integrated to provide an mirror amplitude information signal that is used in a feedback arrangement where the scan amplitude of the mirror is regulated.
Dependencies are inferred from the claim text.