Digital control servo system
First Claim
1. A digital servo system for an optical scanner, comprising a digital processor and computer code, and a signal processing circuit, said circuit comprising a first input for an analog position command signal, a second input for an analog position feedback signal, and an error signal output, said circuit comprising a first circuit element for producing from said position command signal and said position feedback signal an analog position error signal, a second circuit element for producing from said analog position error signal a first digitized error signal known as a high resolution error signal, a third circuit element for producing a digitized said analog position command signal, a fourth circuit element for producing a digitized said analog position feedback signal, said digital processor and computer code generating a second digitized error signal known as a low resolution error signal as a difference signal between said digitized command signal and said digitized feedback signal, said digital processor and computer code providing automatic switching of said error signal output from said high resolution error signal to said low resolution signal during periods when said second circuit element is at its maximum positive or negative output limit.
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Accused Products
Abstract
An improved servo system for galvanometers, scanners and similar devices which uses digital processing to increase the dynamic range and provide greater effective resolution. The system provides digital control of a reference point that directly influences the excitation, which in turn directly influences the gain of the circuit. A high and low resolution switching path is provided to optimize dynamic range. Wide angle torque compensation improves uniformity of response at large angular deflections from zero. Improved thermal protection allows safe operation near system thermal limits. A graphical user interface allows adjustments and changes response on the fly for tuning due to input conditions or user control.
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Citations
15 Claims
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1. A digital servo system for an optical scanner, comprising a digital processor and computer code, and a signal processing circuit, said circuit comprising
a first input for an analog position command signal, a second input for an analog position feedback signal, and an error signal output, said circuit comprising a first circuit element for producing from said position command signal and said position feedback signal an analog position error signal, a second circuit element for producing from said analog position error signal a first digitized error signal known as a high resolution error signal, a third circuit element for producing a digitized said analog position command signal, a fourth circuit element for producing a digitized said analog position feedback signal, said digital processor and computer code generating a second digitized error signal known as a low resolution error signal as a difference signal between said digitized command signal and said digitized feedback signal, said digital processor and computer code providing automatic switching of said error signal output from said high resolution error signal to said low resolution signal during periods when said second circuit element is at its maximum positive or negative output limit.
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5. A digital servo system for an optical scanner, comprising:
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an analog position command signal input, a digital error signal output an analog position feedback signal processing circuit with positive and negative angular position sensors connected to an analog differential amplifier, an analog position error signal with gain, said analog position error signal derived from said analog command and said differential amplifier by said feedback signal processing circuit, a digital processor and computer code, a reference voltage controlled by said processor and computer code connected to said feedback signal processing circuit for controlling gain thereof, a high resolution error signal consisting of a digitized said analog position error signal, a low resolution error signal consisting of a digital differential of a digitized said command signal input and a digitized said analog position error signal, said digital processor and computer code providing automatic switching of said error signal output from said high resolution error signal to said low resolution signal during periods when said second circuit element is at its maximum positive or negative output limit. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 15)
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14. A process for calculating system operating temperature in a galvanometer, comprising the steps of:
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sensing stator temperature of a galvanometer with a thermal sensor proximate the stator, sensing coil current in said galvanometer, calculating temperature rise from stator to coil from effect of coil current, and adding calculated temperature rise to ambient stator temperature.
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Specification