Spinning-vane shaft position encoder

Claim 2

Apparatus for making digital measurements of shaft angular positions comprising: a housing having an axis and having a protruding shaft rotatably mounted on this axis; a shaft-mounted bracket supporting a first scanning means for producing and sensing a first beam of light in a direction parallel to the axis of said housing; a housing-mounted bracket supporting a second scanning means having a second beam of light similar in direction to that of said shaft mounted bracket; an internal shaft rotatably supported by said housing so as to be axially colinear with the axis of said housing; motive means to provide controlled rotational speed of said internal shaft; an opaque vane mounted on said internal shaft for intercepting the light beam positioned by each of said brackets once per revolution of said internal shaft; pulse generating means operatively connected to said vanes and said brackets to generate a series of pulses, the beginning of a series and the end of a series of which are marked by an interception by said vane of the beam of light from one of said brackets; a pulse counter fed by said generating means, the number of pulses fed to said counter by said generating means being proportional to a shaft displacement angle which subtends the first and second light beam interceptions by said vane, thereby providing shaft angle measurement.

Claim 3

Apparatus in accordance with claim 1 further comprising: a second protruding rotatably-mounted shaft coaxial with the rotatably-mounted shaft protruding at the axis of said housing; a second shaft-mounted bracket with a scanning light beam similar in direction to the light beam produced by the first said shaft mounted bracket; a second opaque vane arranged to communicate with second said protruding shaft by alternately interrupting and avoiding the light beam on said second shaft-mounted bracket; and a second pulse generating and counting means for providing a digital measurement of the angular position with respect to a housing-mounted-bracket-confronting position of said second protruding shaft.

Claim 4

Apparatus as set forth in claim 1 wherein shaft position ranges are so limited that the means for electrical connections are adequately provided by loosely-coiled wires.

Claim 5

Apparatus as set forth in claim 1 wherein optical fibers are used between a means for producing the scanning beam of light at a said bracket and a point closer to a said opaque vane.

Claim 6

Apparatus as set forth in clAim 4 wherein optical fibers in the vicinity of the path of said vane are positioned to form the shape of a wedge, thereby directing light through a narrow slit along the apex of the wedge.

Claim 7

Apparatus as set forth in claim 1 wherein said motive means comprises a nearly constant speed motor to drive said vanes, said vanes having greater flywheel inertia than has the motor so that torsional vibrations coming from the motor are isolated and unable to disturb the damped speed of said vanes.

Claim 8

Apparatus for making digital measurements of shaft angle positions comprising: a housing which supports two coaxial, individually rotatable protruding shafts, the axes of which are the central axis of said housing; a first opaque vane mounted inside said housing for spinning about the housing central axis; a second opaque vane fixed to said first vane; a first scanning bracket comprising a light source which directs a beam of light into a photocell in a direction which is parallel to the central axis of said housing; a second and third scanning bracket each also comprising a photocell and a light source supplying an axially-directed beam into its corresponding photocell, all three light beams of said brackets being subject to one interception of one of said vanes per revolution of these vanes, one of said brackets being fixed to said housing and each of the other two being fixed to one of the two shafts protruding from said housing; means for rotating said vanes together around the central axis of said housing with controlled rotational velocity; a source of pulses having a frequency which is controlled and which bears a fixed relationship to the speed of said vane rotative means; and two channels of pulse-counting circuitry, both of which independently measure the elapsed time between a housing-mounted-bracket light beam interception and a corresponding shaft-mounted-bracket light beam interception by one of said vanes in such a way that each pulse count also represents the shaft angle position of one of the protruding shafts.

Claim 9

Apparatus for making digital measurements of shaft angle positions comprising: a housing which supports two coaxial, individually rotatable protruding shafts, the axes of which are the central axis of said housing; a first opaque vane mounted inside said housing for spinning about the housing central axis; a second opaque vane fixed to said first vane; a first scanning bracket comprising a light source which directs a beam of light into a photocell in a direction which is parallel to the central axis of said housing; a second and third scanning bracket each also comprising a photocell and a light source supplying an axially-directed beam into its corresponding photocell, all three light beams of said brackets being subject to one interception of one of said vanes per revolution of these vanes, one of said brackets being fixed to said housing and each of the other two being fixed to one of the two shafts protruding from said housing; means for rotating said vanes together around the central axis of said housing with controlled rotational velocity; a source of pulses having a frequency which is controlled and which bears a fixed relationship to the speed of said vane rotative means; and two channels of pulse-counting circuitry, both of which independently measure the elapsed time between a housing-mounted-bracket light beam interception and a corresponding shaft-mounted-bracket light beam interception by one of said vanes in such a way that each pulse count also represents the shaft angle position of one of the protruding shafts.

Claim 10

Apparatus in accordance with claim 7 further comprising: additional individually rotatable shafts protruding from said housing, all of said shafts in addition to said housing having a single axis; one additional scanning bracket with a light beam source and photocell for each said additional protruding shaft; one additional spinning vane fitted for rotation along with other said vanes for each said additional protruding shaft; and one additional channel of pulse counting circuitry for each said additional protruding shaft, said additional channel serving independently of other said channels to perform a digital shaft angle measurement of said additional protruding shaft.