Positioning system

Claim 2

In a positioning system having count pulses applied to a counter, the pulse count in said counter indicating position of a moving member along a given path, an error correction system comprising: a plurality of correction indication means, each of said correction indication means disposed at a predetermined position along said given path where a one pulse count correction of said counter is required; detecting means for detecting each of said correction indication means and for generating a pair of correction signals in response to each of said correction indication means, the time relationship of the signals in each pair of correction signals being indicative of the direction of movement of said moving member; circuit means for receiving each pair of correction signals, said circuit means generating one correction pulse in response to each pair of correction signals, said correction pulse being additive when said moving member is moving in one direction and being subtractive when said moving member is moving in the opposite direction; and means for applying each correction pulse to said counter to correct its pulse count.

Claim 3

An error correction system as claimed in claim 1 wherein said correction pulse is applied to said counter at a time other than when said count pulses are being applied to said counter.

Claim 4

An error correction system as claimed in claim 1 wherein said correction indication means comprises: light interrupting means having light admitting perforations therein at said predetermined positions; and a light source.

Claim 5

An error correction system as claimed in claim 1 where said correction indication means comprises: light reflective means disposed at said predetermined positions; and a light source.

Claim 6

An error correction system as claimed in claim 3 wherein said detecting means comprises: light sensitive photocells.

Claim 7

An error correction system as claimed in claim 4 wherein said detecting means comprises: light sensitive photocells.

Claim 8

An error correction system for introducing predetermined corrections into a position measuring system, said position measuring system addIng counts to a counter to indicate movement of a moving member in one direction along a given path and subtracting counts from said counter to indicate movement of said moving member in the opposite direction, the number of counts in said counter being indicative of the position of said moving member along said given path, said error correction system comprising: indicating means providing an indication at predetermined positions along said given path at which a correction is required; a first detector to detect the indication provided by said indicating means and to generate a first signal in response thereto; a second detector positioned adjacent to said first detector to detect the indication provided by said indicating means and to generate a second signal in response thereto, said second signal being spaced in time relationship from said first signal; circuit means coupled to said first and second detectors for receiving said first and second signals, said circuit means being responsive to said time relationship of said first and second signals to determine the direction of movement of said moving member, said circuit means generating an additive correction pulse when said moving member is moving in said one direction and a subtractive correction pulse when said moving member is moving in said opposite direction; and means coupled to said circuit means and to said counter for applying to said counter whichever of said additive correction pulse or said subtractive correction pulse is generated, said additive correction pulse causing one count to be added to said counter and said subtractive correction pulse causing one count to be subtracted from said counter.

Claim 9

An error correction system for introducing predetermined corrections into a position measuring system, said position measuring system addIng counts to a counter to indicate movement of a moving member in one direction along a given path and subtracting counts from said counter to indicate movement of said moving member in the opposite direction, the number of counts in said counter being indicative of the position of said moving member along said given path, said error correction system comprising: indicating means providing an indication at predetermined positions along said given path at which a correction is required; a first detector to detect the indication provided by said indicating means and to generate a first signal in response thereto; a second detector positioned adjacent to said first detector to detect the indication provided by said indicating means and to generate a second signal in response thereto, said second signal being spaced in time relationship from said first signal; circuit means coupled to said first and second detectors for receiving said first and second signals, said circuit means being responsive to said time relationship of said first and second signals to determine the direction of movement of said moving member, said circuit means generating an additive correction pulse when said moving member is moving in said one direction and a subtractive correction pulse when said moving member is moving in said opposite direction; and means coupled to said circuit means and to said counter for applying to said counter whichever of said additive correction pulse or said subtractive correction pulse is generated, said additive correction pulse causing one count to be added to said counter and said subtractive correction pulse causing one count to be subtracted from said counter.

Claim 10

An error correction system for introducing predetermined corrections into a position measuring system, said position measuring system adding counts to a counter to indicate movement of a moving member in one direction along a given path and subtracting counts from said counter to indicate movement of said moving member in the opposite direction, the number of counts in said counter being indicative of the position of said moving member along said given path, said error correction system comprising: indicating means providing an indication at predetermined positions along said given path at which a correction is required; a first detector to detect the indication provided by said indicating means and to generate a first signal in response thereto; a second detector positioned adjacent to said first detector to detect the indication provided by said indicating means and to generate a second signal in response thereto, said second signal being spaced in time relationship from said first signal; circuit means coupled to said first and second detectors for receiving said first and second signals, said circuit means being responsive to said time relationship of said first and second signals to determine the direction of movement of said moving member, said circuit means generating an additive correction pulse when said moving member is moving in said one direction and a subtractive correction pulse when said moving member is moving in said opposite direction; and means coupled to said circuit means and to said counter for applying to said counter whichever of said additive correction pulse or said subtractive correction pulse is generated, said additive correction pulse causing one count to be subtracted from said counter and said subtractive correction pulse causing one count to be added to said counter.

Claim 11

An error correction system for introducing predetermined corrections into a position measuring system, said position measuring system adding counts to a counter to indicate movement of a moving member in one direction along a given path and subtracting counts from said counter to indicate movement of said moving member in the opposite direction, the number of counts in said counter being indicative of the position of said moving member along said given path, said error correction system comprising: indicating means providing an indication at predetermined positions along said given path at which a correction is required; a first detector to detect the indication provided by said indicating means and to generate a first signal in response thereto; a second detector positioned adjacent to said first detector to detect the indication provided by said indicating means and to generate a second signal in response thereto, said second signal being spaced in time relationship from said first signal; circuit means coupled to said first and second detectors for receiving said first and second signals, said circuit means being responsive to said time relationship of said first and second signals to determine the direction of movement of said moving member, said circuit means generating an additive correction pulse when said moving member is moving in said one direction and a subtractive correction pulse when said moving member is moving in said opposite direction; and means coupled to said circuit means and to said counter for applying to said counter whichever of said additive correction pulse or said subtractive correction pulse is generated, said additive correction pulse causing one count to be subtracted from said counter and said subtractive correction pulse causing one count to be added to said counter.

Claim 12

In a positioning system having a positioning mechanism for moving a member along a given path and including a count generator for generating a count signal for each increment of movement of an element of said positioning mechanism and in which the physical incremental displacement of said member by said mechanism is consistently in error with he number of count signals generated when said member is at a predetermined point along said path, an error coRrection system which comprises: error correction generating means having a first element disposed along said path of movement near said predetermined point and having a second element adapted to be coupled to said positioning mechanism for movement with said member along said path for generating an error correction signal when said elements are in proximity; counter means adapted to be coupled to said count signal generator for receiving said count signals; and timing means responsive to said count signal and to said error correction signal for coupling an error correction signal to said counter means intermediate successive count signals

Claim 13

In a positioning system having a positioning mechanism for moving a member along a given path and including a count generator for generating a count signal for each increment of movement of an element of said positioning mechanism and in which the physical incremental displacement of said member by said mechanism is consistently in error with he number of count signals generated when said member is at a predetermined point along said path, an error coRrection system which comprises: error correction generating means having a first element disposed along said path of movement near said predetermined point and having a second element adapted to be coupled to said positioning mechanism for movement with said member along said path for generating an error correction signal when said elements are in proximity; counter means adapted to be coupled to said count signal generator for receiving said count signals; and timing means responsive to said count signal and to said error correction signal for coupling an error correction signal to said counter means intermediate successive count signals