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US 4,728,788 AGranted
Position encoder apparatus
AssigneeGilbarco Inc.
InventorsHoward M. Myers, Benjamin T. Siler
Life of this patent
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AssigneeGilbarco Inc.
InventorsHoward M. Myers, Benjamin T. Siler
Estimating the term…
A shaft encoder for deriving a number of pulses indicative of the extent of rotary shaft motion including a disc having plural relatively narrow opaque regions spaced from each other by relatively wide transparent regions. Light from a pair of sources is directed through the regions toward a pair of light detectors. The detectors and regions are such that under normal operation light from the sources is incident on at least one of the detectors. The wide regions have an extent sufficiently great to prevent them from being clogged by dirt and other debris. In response to neither of the detectors having light incident on them, an indication of a failure of the shaft encoder is provided and operation of an accumulator responsive to the number of light transitions incident on the detectors is prevented. Thereby, a fail-safe apparatus is provided in the event of a failure of any of the light sources, the detectors and circuitry responsive thereto.
Apparatus for deriving pulses indicative in number of the movement of a mechanical member comprising optical energy source means, a pair of detectors for energy from the source means, an encoder transducer adapted to be mounted for movement with the member, the encoder transducer including plural relatively narrow substantially equi-spaced and equi-length regions spaced from each other by relatively wide substantially equi-spaced and equi-length regions so that as the encoder transducer moves in response to movement of the member, optical energy from the source means is prevented from reaching the detectors by the narrow regions to cast shadows on the detectors and optical energy from the source means is incident on the detector via a path including the wide regions, the detectors and regions being positioned and the field of view of the detectors in response to the optical energy of the source means being such that under normal operation optical energy from the source means is always incident on at least one of the detectors at a particular time and is incident on both of the detectors at other times, the wide regions having an extent sufficiently great to prevent them from being clogged by dirt and other debris.
Apparatus for deriving pulses indicative in number to the movement of a shaft comprising first and second optical sources, first and second optical energy detectors respectively responsive to energy from the first and second sources, an encoder disc adapted to be mounted for movement with the shaft, the encoder disc including plural relatively narrow substantially equi-spaced and equi-length arcuate opaque regions spaced from each other by relatively wide substantially equi-spaced and equi-length arcuate transparent regions so that as the encoder disc turns in response to turning of the shaft, optical energy from the first and second sources is prevented from reaching the first and second detectors by the narrow regions to cast shadows on the detectors and optical energy from the first and second sources is incident on the first and second detector via paths including the wide regions, the sources, detectors and regions being positioned such that under normal operation optical energy from the first and second sources is always incident on at least one of the first and second detectors at a particular time and is incident on both of the detectors at other times, the wide regions having an extent sufficiently great to prevent them from being clogged by dirt and other debris.
Apparatus for deriving pulses indicative in number of the movement of a mechanical member in response to pulses derived by a pair of detectors responsive to energy from an optical energy source means propagating through an encoder transducer adapted to be mounted for movement with the member, the encoder transducer including plural relatively narrow substantially equi-spaced and equi-length regions spaced from each other by relatively wide substantially equi-spaced and equi-length regions so that as the encoder transducer moves in response to movement of the member, optical energy from the source means is prevented from reaching the detectors by the narrow regions to cast shadows on the detectors and optical energy from the source means is incident on the detector via a path including the wide regions, the detectors and regions being positioned and the field of view of the detectors in response to the optical energy of the source means being such that under normal operation optical energy from the source means is always incident on at least one of the detectors at a particular time and is incident on both of the detectors at other times, the wide regions having an extent sufficiently great to prevent them from being clogged by dirt and other debris, the apparatus comprising:
Apparatus for deriving pulses indicative in number to the movement of a mechanical member mechanically coupled for movement with an encoder transducer adapted to be mounted for movement with the member, the encoder transducer including plural relatively narrow substantially equi-spaced and equi-length regions spaced from each other by relatively wide substantially equi-spaced and equi-length regions, the apparatus comprising optical energy source means, a pair of detectors for energy from the source means, the source means, detectors and encoder transducer being such that as the encoder transducer moves in response to movement of the member optical energy from the source means is prevented from reaching the detectors by the narrow regions to cast shadows on the detectors and optical energy from the source means is incident on the detector via a path including the wide regions, the detectors and regions being positioned and the field of view of the detectors in response to the optical energy of the source means being such that under normal operation optical energy from the source means is always incident on at least one of the detectors at a particular time and is incident on both of the detectors at other times, the wide regions having an extent sufficiently great to prevent them from being clogged by dirt and other debris, each detector including a phototransistor having an emitter collector path, the emitter collector paths being connected in parallel between a pair of power supply terminals and having a common collector load resistor connected to one of the power supply terminals so that the emitter collector voltages of both paths remain relatively low under normal operation even when one of the phototransistors has a high emitter collector impedance in response to said one transistor not being illuminated by optical energy from the source means, and a separate emitter output circuit for each of said phototransistors for deriving a signal indicative of the amount of optical energy incident on the respective phototransistor.
Dependencies are inferred from the claim text.