Motor-driven positioning system with reflective optical encoder
First Claim
1. In a motor-driven positioning system having a current-driven brushless DC motor provided with an optical encoder furnishing first electrical signals for determining rotor position and furnishing second electrical signals for commutating the motor drive current, the improvement comprisingthe optical encoder having a pattern of relatively reflective and non-reflective areas,a plurality of radiation emitter and detector means positioned such that radiation from at least one of said plurality of respective emitter means reflected from the reflective areas is detected by at least one of said plurality of respective detector means, andmeans connected to the detector means for deriving at least one of the first and second electrical signals from the detected radiation reflected from the detected areas,said optical encoder having a stationary pattern and a moveable disk located between said plurality of radiation emitter and detector means and the stationary pattern.
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Accused Products
Abstract
A low cost, high resolution optical encoder for a brushless DC motor comprises reflective sensors, and a movable disk cooperating with a stationary pattern to provide a pattern of reflective and non-reflective areas for the sensors that can be used to generate motor positional information as well as commutation drive signals.
48 Citations
13 Claims
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1. In a motor-driven positioning system having a current-driven brushless DC motor provided with an optical encoder furnishing first electrical signals for determining rotor position and furnishing second electrical signals for commutating the motor drive current, the improvement comprising
the optical encoder having a pattern of relatively reflective and non-reflective areas, a plurality of radiation emitter and detector means positioned such that radiation from at least one of said plurality of respective emitter means reflected from the reflective areas is detected by at least one of said plurality of respective detector means, and means connected to the detector means for deriving at least one of the first and second electrical signals from the detected radiation reflected from the detected areas, said optical encoder having a stationary pattern and a moveable disk located between said plurality of radiation emitter and detector means and the stationary pattern.
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13. A motor-driven positioning system comprising:
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(a) a brushless DC motor having a rotor whose position is to be set, (b) electronic driving means connected to the motor for operating same to change the position of its rotor, (c) an optical encoder connected to and rotatable with the rotor, said optical encoder comprising a member having first and second sides and having on said first side a pattern of relatively reflective and non-reflective areas, (d) first means adjacent said first side of the encoder member for directing thereon a beam of radiation capable of reflection from said reflective areas, (e) second means adjacent said first side of the encoder member for detecting radiation from said first means reflected from said reflective areas and converting same to electrical signals, (f) third means for processing said electrical signals to determine whether the rotor is at a desired position, (g) fourth means connected between said third means and said electronic drive means for providing the latter with driving signals to cause the rotor to rotate to the desired position, and (h) fifth means for processing said electrical signals to provide commutation for the electronic drive means wherein said optical encoder having a moveable disk with patterned holes rotating between a stationary pattern of relatively reflective and non-reflective areas and the first and second means.
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Specification