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US 7,126,734 B1Granted
Motor drive circuit with reduced coil crosstalk in a feedback signal indicative of mirror motion in light scanning arrangements
AssigneeSymbol Technologies, Inc.
InventorsJames Giebel, Costanzo Difazio, Mark A. Weitzner
Life of this patent
Estimating the term…
Abstract
Crosstalk between a drive coil and a feedback coil is eliminated by a motor drive circuit operative for generating the drive coil as a square wave, and by removing the crosstalk which occurs at zero transitions of a feedback signal. The drive coil is used to oscillate a scan mirror employed in an image projection arrangement or an electro-optical reader.
Claims14
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;
- and
- d) circuitry for processing the uncorrupted feedback signal to generate the drive signal as a square wave having vertical edges respectively corresponding to the zero crossings.
2 more elements
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;
- and
- d) processing the uncorrupted feedback signal to generate the drive signal as a square wave having vertical edges respectively corresponding to the zero crossings.
2 more elements
Dependencies are inferred from the claim text.