Portable laser scanning system having a motor drive with no DC windings
First Claim
1. A scanning device for repetitively scanning a target, said device having a laser beam generating means, at least one high speed scanning motor having a reflection means mounted on a drive shaft of said high speed scanning motor for directing the laser beam provided by said laser beam generating means, and a motor drive circuit being an open-loop control system for adjusting the amplitude of oscillation of the scanning motor to a predetermined level and presetting the frequency of oscillation of the scanning motor to a predetermined level comprising a waveform generation means to supply a first and second periodic, time varying triangular waveform to a pair of stator windings in the scanning motor, said first and second periodic, time-varying triangular waveforms being of equal magnitude and 180 degrees out of phase with respect to one another so as to cause increasing and decreasing current flow in alternate stator windings of said pair of stator windings and corresponding increasing and decreasing magnetization in said alternate stator windings, said increasing and decreasing magnetization in alternate stator windings providing smooth reflection means rotation and to maximize said reflection means rotation.
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Accused Products
Abstract
A lightweight hand-held scanning device for repetitively scanning a laser light source having a laser light generating means and at least one high speed scanning motor controlled by a motor drive circuit which adjusts the amplitude and presets the frequency of oscillation of a high speed scanning motor. The frequency and amplitude regulation is accomplished by using an open loop control system that supplies two opposing stator windings of the scanning motor with a pair of periodic triangular current waveforms that are 180 degrees out of phase for energizing an de-energizing the stator coils respectively. The energizing and de-energizing of the opposing stator coils causes variations in the magnetic strength of these coils, thereby causing the rotor to alternately align itself with the energizing stator coil which results in a smooth oscillating motion of the motor shaft. By adjusting the amplitude, and presetting the frequency of oscillation of the high speed scanning motor, the motor can maintain a consistent scanning speed and use less power.
44 Citations
16 Claims
- 1. A scanning device for repetitively scanning a target, said device having a laser beam generating means, at least one high speed scanning motor having a reflection means mounted on a drive shaft of said high speed scanning motor for directing the laser beam provided by said laser beam generating means, and a motor drive circuit being an open-loop control system for adjusting the amplitude of oscillation of the scanning motor to a predetermined level and presetting the frequency of oscillation of the scanning motor to a predetermined level comprising a waveform generation means to supply a first and second periodic, time varying triangular waveform to a pair of stator windings in the scanning motor, said first and second periodic, time-varying triangular waveforms being of equal magnitude and 180 degrees out of phase with respect to one another so as to cause increasing and decreasing current flow in alternate stator windings of said pair of stator windings and corresponding increasing and decreasing magnetization in said alternate stator windings, said increasing and decreasing magnetization in alternate stator windings providing smooth reflection means rotation and to maximize said reflection means rotation.
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4. A miniature, hand-held scanning device for repetitively scanning a target with laser light, said device having a laser beam generating means, at least one high speed scanning motor, said motor having first and second stator windings, a permanent magnet rotor, a shaft connected to said rotor having light reflecting means attached thereto and being operable to oscillate in alternate circumferential directions, and a motor drive circuit for adjusting the amplitude of oscillation and presetting the frequency of oscillation of said scanning motor, said motor drive circuit being an open-loop control system comprising:
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a voltage regulator means for generating a constant dc voltage, said constant dc voltage provides an input signal to a signal generator means which generates a periodic, time-varying voltage waveform of preselected amplitude and frequency; a variable gain attenuator means for scaling the output of said periodic, time-varying voltage waveform; and a voltage-to-current converting means for converting said periodic voltage waveform into a first and second periodic time-varying, triangular current waveform, said first and second waveforms are input into said first and second stator windings of said scanning motor. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11)
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- 12. A method for repetitively scanning a target with light by adjusting the amplitude of oscillation and presetting the frequency of oscillation of a scanning motor, having light reflecting means mounted on a shaft thereof to a predetermine level, comprising supplying a first and second periodic, time-varying triangular waveforms to a pair of stator windings in the scanning motor, said first and second periodic, time-varying triangular waveforms being of equal magnitude and 180 degrees out of phase with respect one another so as to cause increasing and decreasing current flow in alternate stator windings of said pair of stator windings and corresponding increasing and decreasing magnetization in said alternate stator windings, said increasing and decreasing magnetization in alternate stator windings providing smooth light reflecting means rotation and to maximize said light reflecting means rotation.
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14. A method for repetitively scanning a target with light by adjusting the amplitude and presetting the frequency of oscillation of a scanning motor, said motor having first and second stator windings, a permanent magnet rotor, and a shaft connected to the rotor having light reflective means mounted thereon and being operative to oscillate in alternate circumferential directions, said method comprising:
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generating a constant dc voltage to provide an input signal to a signal generating means; generating a periodic time-varying voltage waveform; scaling the periodic, time-varying voltage waveform in order to adjust its amplitude; converting said periodic, time-varying voltage waveform into a pair of periodic, time-varying current waveforms which are of equal magnitude, and 180 degrees out of phase with respect to one another; and supplying the pair of periodic, time-varying current waveforms to said first and second stator windings of said scanning motor so as to cause increasing and decreasing current flow in alternate stator windings of said pair of stator windings and corresponding increasing and decreasing magnetization in said alternate stator windings, said increasing and decreasing magnetization in alternate stator windings provides for smooth light reflective means rotation and to maximize said light reflective means rotation. - View Dependent Claims (15, 16)
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Specification