Encoder for measuring both incremental and absolute positions of moving elements

A decoding apparatus actuated by three analog signal voltages from an encoder for determining the incremental and absolute positions of a movable member relative to a stationary member, said encoder having three sensing means for producing said three analog voltages from a timing track and a data track, comprising:

• (1) timing track phase comparator means connected to two timing sensing means for comparing the phase relationship of their two analog signal voltages and producing a direction level signal and a clock pulse signal,
• (2) up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current position of said movable member,
• (3) left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third analog signal voltage,
• (4) right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third analog signal voltage,
• (5) left-motion mask register means connected to said direction level and clock pulse signal,
• (6) right-motion mask register means connected to said direction level and clock pulse signal,
• (7) two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• (8) absolute position register means connected to both said shift register means, and
• (9) position comparator means connected to said absolute position register means and to said up/down counter means.

An optical encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• three light sources supported by one said member for emitting three narrow light beams on respective paths,
• an encoding band supported by the other said member in the paths of said light beams, said band having
• at least one timing and incremental encoding track comprising least one series of alternating light-blocking stripes and light-passing stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said one said member and having three non-sweeping optical sensors, one for each said light beam, two in quadrature with each other for said timing and incremental encoding track, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• said movable member being capable of both discrete and continuous motion in both directions,
• decoding means actuated by said analog signal voltages for determining the incremental and absolute positions of said movable member relative to said stationary member, and
• whereby said absolute and incremental positions can be determined solely from said system without dependence on any additional information external to said system.

An encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• three light sources supported by one said member for sending three narrow light beams on respective paths,
• a continuous circular encoding band supported by the other said member in the paths of said light beams, said band having
• a timing and incremental encoding track comprising at least one series of alternating light-blocking stripes and light-passing stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said one said member and having three non-sweeping optical sensors, one for each said light beam, two in quadrature with each other for said timing and incremental encoding track, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• comparator means connected to said two timing-track optical sensors for comparing the phase relationship of their two signal voltages and producing a direction level signal and a clock pulse signal,
• up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current position of said movable member,
• left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third optical sensor,
• right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third optical sensor,
• left-motion mask register means connected to said direction level and clock pulse signal,
• right-motion mask register means connected to said direction level and clock pulse signal,
• two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• absolute position register means connected to both said shift register means, and
• position comparator means connected to said absolute position register means and to said up/down counter means.

An encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• an encoding band supported by one said member, said band having
• a single timing track for timing and incremental encoding, comprising a series of alternating dark stripes and reflective stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by the other said member and having three non-sweeping optical sensors, two for said timing track, being spaced apart to provide quadrature, and one for said data track, each said optical sensor including a light source coupled with light sensing means for generating an analog signal voltage,
• timing track phase comparator means connected to said two timing-track optical sensors for comparing the phase relationship of their two signal voltages and producing a direction level signal and a clock pulse signal,
• up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current position of said movable member,
• left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third optical sensor,
• right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third optical sensor,
• left-motion mask register means connected to said direction level and clock pulse signal,
• right-motion mask register means connected to said direction level and clock pulse signal,
• two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• absolute position register means connected to both said shift register, and
• position comparator means connected to said absolute position register means and to said up/down counter means.

An encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• an encoding band supported by one said member, said band having
• a single timing track for timing and incremental encoding comprising a series of alternating opaque stripes and transparent stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• three light source means supported by the other said member and directing respective beams toward said band,
• a read head supported by said other member and having three optical sensors on the opposite side of said band from said light source means, two for said timing track, being spaced apart to provide quadrature, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• timing track phase comparator means connected to said two timing-track optical sensors for comparing the phase relationship of their two signal voltages and producing a direction level signal and a clock pulse signal,
• up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current position of said movable member,
• left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third optical sensor,
• right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third optical sensor,
• left-motion mask register means connected to said direction level and clock pulse signal,
• right-motion mask register means connected to said direction level and clock pulse signal,
• two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• absolute position register means connected to both said shift register means, and
• position comparator means connected to said absolute position register means and to said up/down counter means.

In a system for determining the absolute and the incremental positions of a movable telescope dome of a dome building having a stationary portion, the combination of:

• a circular encoding band supported by said movable dome, said band having
• a timing track for timing and incremental encoding comprising at least one series of narrow stripes all around said band, alternating light-absorbing and light-passing stripes, and
• a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said stationary portion of said dome building and having three optical sensors aimed at said band, two for said timing track, being spaced apart a predetermined distance for quadrature, and one for said data track, each said optical sensor including a light-emitting diode coupled with a phototransistor for generating an analog signal voltage from the transmission of the light-emitting diode light from said tracks,
• said read head being mounted on wheels in rolling contact with said band and mounted to said stationary portion through a parallelogram linkage and spring-urged toward a set distance from said band, so that out-of-roundness of said dome is compensated.

An optical encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• three light sources supported by one said member for emitting three narrow light beams on respective paths,
• an encoding band supported by the other said member in the paths of said light beams, said band having
• a single timing and incremental encoding track comprising at least one series of alternating light-blocking stripes and light-passing stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track, and
• a read head supported by said one said member and having three non-sweeping optical sensors, one for each said light beam, two in quadrature with each other for said timing and incremental encoding track, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• said movable member being capable of both discrete and continuous motion in both directions,
• whereby said absolute and incremental positions can be determined solely from said system without dependence on any additional information external to said system.

An encoding system for determining the absolute and the incremental positions of a movable telescope dome of a dome building having a stationary portion, including in combination:

• an encoding band supported by a generally cylindrical surface of said movable dome around the complete circle thereof, said band having
• a timing track for timing and incremental encoding comprising a series of narrow stripes all around said band, alternating dark and reflective stripes, and
• a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said stationary portion of said dome building and having three non-sweeping optical sensors aimed at said band, two for said timing track, being spaced apart a predetermined distance, and one for said data track, each said optical sensor including a light-emitting diode coupled with a phototransistor for generating an analog signal voltage from the reflection of the light-emitting diode light from said tracks,
• said read head being mounted to its rigid support through a parallelogram linkage, and spring means urging it toward a set distance from said band, so that out-of-roundness of said dome is compensated.

An encoding system for determining the absolute and the incremental positions of a movable telescope dome of a domed building having a stationary portion, including in combination:

• an encoding band supported by a generally cylindrical surface of said movable dome around the complete circle thereof, said band having
• a timing track for timing and incremental encoding comprising a series of narrow stripes all around said band, alternating dark and reflective stripes, and
• a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for enclosing the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said stationary portion of said dome building and having three non-sweeping optical sensors aimed at said band, two for said timing track, being spaced apart a predetermined distance, and one for said data track, each said optical sensor including a light-emitting diode coupled with a phototransistor for generating an analog signal voltage from the reflection of the light-emitting diode light from said tracks,
• said read head being mounted on wheels in rolling contact with said cylindrical surface.

An encoding system for determining the absolute and the incremental positions of a movable telescope dome of a dome building having a stationary portion, including in combination:

• an encoding band supported by a generally cylindrical surface of said movable dome around the complete circle thereof, said band having
• a timing track for timing and incremental encoding comprising a series of narrow stripes all around said band, alternating dark and reflective stripes, and
• a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• a read head supported by said stationary portion of said dome building and having three non-sweeping optical sensors aimed at said band, two for said timing track, being spaced apart a predetermined distance, and one for said data track, each said optical sensor including a light-emitting diode coupled with a phototransistor for generating an analog signal voltage from the reflection of the light-emitting diode light from said tracks,
• timing track phase comparator means connected to said two timing-track optical sensors for comparing the phase relationship of their two signal voltages and producing a direction level signal and a clock pulse signal,
• up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current dome position,
• dome left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third optical sensor,
• dome right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third optical sensor,
• dome left-motion mask register means connected to said direction level and clock pulse signal,
• dome right-motion mask register means connected to said direction level and clock-pulse signal,
• two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• absolute position register means connected to both said shift register means, and
• position comparator means connected to said absolute position register means and to said up/down counter means.

An encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• a circular encoding band on said movable member, said band having
• a single timing track means for timing and incremental encoding comprising a series of alternating opaque stripes and transparent stripes, and
• a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• three light source means mounted on said stationary member and directing respective beams toward said band, and
• a read head secured to said stationary member and having three non-sweeping optical sensors on the opposite side of said band from said light source means, two for said timing track, being spaced apart, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• said members being capable of both discrete and continuous motion in both directions around a circular path,
• whereby said absolute and incremental positions can be determined solely from said system without dependence on any additional information external to said system.

An encoding system for determining the absolute and the incremental positions of a movable member relative to a stationary member, including in combination:

• a circular encoding band on said movable member, said band having
• timing track means for timing and incremental encoding comprising a series of alternating opaque stripes and transparent stripes, and
• a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track,
• three light source means mounted on said stationary member and directing respective beams toward said band,
• a read head secured to said stationary member and having three optical sensors on the opposite side of said band from said light source means, two for said timing track, being spaced apart, and one for said data track, each said optical sensor including light sensing means for generating an analog signal voltage,
• timing track phase comparator means connected to said two timing-track-means optical sensors for comparing the phase relationship of their two signal voltages and producing a direction level signal and a clock pulse signal,
• up/down counter means connected to said direction level and clock pulse signals and having readout means for indicating the current position of said movable member,
• left-motion serial shift register means connected to said direction level and clock pulse signals and also to said third optical sensor,
• right-motion serial shift register means connected to said direction level and clock pulse signal and also to said third optical sensor,
• left-motion mask register means connected to said direction level and clock pulse signals,
• right-motion mask register means connected to said direction level and clock pulse signals,
• two framing gating means, each connected to said clock pulse signal and to one of said mask register means,
• absolute position register means connected to both said shift register means, and
• position comparator means connected to said absolute position register means and to said up/down counter means.

A method for determining the absolute and the incremental positions of a movable member relative to a stationary member, comprising the steps of:

• sending three separate beams of light toward one said member,
• intercepting said beams by an encoding band secured to the other said member, said band having a timing track for timing and incremental encoding portion comprising a series of narrow alternating light-beam blocking and light-beam passing stripes and a data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag, and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track, two of said light beams being directed at spaced-apart loci along said timing track and one directed to a locus along said data track,
• generating an analog signal voltage from the light from each beam after the interception, two such voltages from said timing track and one from said data track,
• comparing the phase relationship of the two analog voltages from said timing track and producing direction level signals and clock pulse signals therefrom,
• counting the clock pulse signals, thereby indicating the current incremental position of said movable member,
• sending said direction level and clock pulse signals and a logic level derived from the third analog voltage to left-motion serial shift register means, and also to right-motion serial shift register means,
• framing the output from each said shift register means and sending the resultant output of each to absolute position register means,
• comparing the absolute position register values with those from said counting step, and
• resetting said incremental position to match the value contained in the absolute position register means, should they disagree.

A method for encoding the absolute and the incremental positions of a movable member relative to a stationary member, comprising the steps of:

• sending three separate beams of light toward a stationary position,
• intercepting said beams by an encoding band secured to said movable member, said band having a timing track for timing and incremental encoding portion comprising a series of narrow alternating light-beam blocking and light-beam passing stripes and a single data track comprising a series of absolute position tags disposed at regular intervals along said data track, each said tag being distinctly different from every other said tag and each comprising a serial bit stream for encoding the absolute position corresponding to the location of its tag along said data track, two of said light beams being directed at spaced-apart loci along said timing track and one directed to a locus along said data track,
• generating an analog signal voltage from the light from each beam after the interception, two such voltages in quadrature from said timing track and one from said data track,
• said members being capable of both discrete and continuous motion in both directions around a circular path, and
• whereby said absolute and incremental positions can be determined solely from said system without dependence on any additional information external to said system.