Chain code encoder
First Claim
1. An apparatus providing information of the position of a rotating member having an axis of rotation, comprisingcode means positioned for rotation with the rotating member for providing a code sequence of code cycles arranged circumferentially about the axis of rotation of the rotating member, wherein each code cycle is associated with a unique position of the rotating member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the rotating member wherein the code sequence comprises a series of bits formed by the bits occupying a selected bit position in each of the words in a sequence of N-bit code words the sequence of N-bit code words being formed according to the steps of:
- a. beginning with all N-bits of a first N-bit code word in a first logic state;
b. shifting the bits in the first N-bit code word by one bit position so that a bit position is vacated;
c. setting the vacated bit position to a second logic state, different from the first logic state, to form a new N-bit code word and assigning the new N-bit code word to the sequence of N-bit code words if the new N-bit code word does not match any of the other N-bit code words in the sequence of N-bit code words;
d. setting the vacated bit position to the first logic state to form an alternate N-bit code word and assigning the alternate N-bit code word to the sequence of N-bit code words if the new N-bit code word of step "c" matches any of the other N-bit code words in the sequence of N-bit code words; and
e. repeating steps "b" through "d" until 2N N-bit code words are present in the sequence of N-bit code words, wherein in step "b" the "first N-bit code word" is replaced by the N-bit code word that was assigned to the sequence of N-bit code words in steps "c" and "d";
means for reading the code cycles of the code sequence which are brought into instantaneous registration with a monitoring point as the rotating member is rotated, wherein the monitoring point is fixed in position relative to the rotating member;
means coupled to the reading means for extracting the position data from the code cycles being read by the reading means and for temporarily storing the position data in the order received; and
means coupled to the extracting and storing means for converting the consecutive sequence of the N most recently received position data into positional information.
1 Assignment
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Accused Products
Abstract
A positional encoder which provides absolute position information from a single code track. A chain code track is positioned on a code disk to supply position words of N consecutive bits, each position word being unique and corresponding to a different position of the code disk. Means are provided for detecting the elements of the chain code as the code disk is rotated with respect to a fixed point. The position data are accumulated in the order received and N consecutive bits are examined to determine the position to which the bits correspond.
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Citations
15 Claims
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1. An apparatus providing information of the position of a rotating member having an axis of rotation, comprising
code means positioned for rotation with the rotating member for providing a code sequence of code cycles arranged circumferentially about the axis of rotation of the rotating member, wherein each code cycle is associated with a unique position of the rotating member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the rotating member wherein the code sequence comprises a series of bits formed by the bits occupying a selected bit position in each of the words in a sequence of N-bit code words the sequence of N-bit code words being formed according to the steps of: -
a. beginning with all N-bits of a first N-bit code word in a first logic state; b. shifting the bits in the first N-bit code word by one bit position so that a bit position is vacated; c. setting the vacated bit position to a second logic state, different from the first logic state, to form a new N-bit code word and assigning the new N-bit code word to the sequence of N-bit code words if the new N-bit code word does not match any of the other N-bit code words in the sequence of N-bit code words; d. setting the vacated bit position to the first logic state to form an alternate N-bit code word and assigning the alternate N-bit code word to the sequence of N-bit code words if the new N-bit code word of step "c" matches any of the other N-bit code words in the sequence of N-bit code words; and e. repeating steps "b" through "d" until 2N N-bit code words are present in the sequence of N-bit code words, wherein in step "b" the "first N-bit code word" is replaced by the N-bit code word that was assigned to the sequence of N-bit code words in steps "c" and "d"; means for reading the code cycles of the code sequence which are brought into instantaneous registration with a monitoring point as the rotating member is rotated, wherein the monitoring point is fixed in position relative to the rotating member; means coupled to the reading means for extracting the position data from the code cycles being read by the reading means and for temporarily storing the position data in the order received; and means coupled to the extracting and storing means for converting the consecutive sequence of the N most recently received position data into positional information. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus providing information of the position of a rotating member having an axis of rotation, comprising
code means positioned for rotation with the rotating member for providing a code sequence of code cycles arranged circumferentially about the axis of rotation of the rotating member, wherein each code cycle is associated with a unique position of the rotating member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the rotating member; -
means for reading the code cycles of the code sequence which are brought into instantaneous registration with a monitoring point as the rotating member is rotated, wherein the monitoring point is fixed in position relative to the rotating member; means coupled to the reading means for extracting the position data from the code cycles being read by the reading means and for temporarily storing the position data in the order received; and means coupled to the extracting and storing means for converting the consecutive sequence of the N most recently received position data into positional information, wherein each of the code cycles include synchronizing information and the position data are encoded by varying the duty cycle in the code cycle, so that synchronizing information and position data are included in a single code sequence, and further wherein the extracting and storing means include means coupled to the reading means for deriving the synchronizing information from the code cycles being read; and means responsive to the synchronizing information for designating the point in the code cycle being read which is indicative of the position data. - View Dependent Claims (7)
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8. An apparatus providing information of the position of a rotating member having an axis of rotation, comprising
code means positioned for rotation with the rotating member for providing position data and synchronizing information, including a first sequence of code cycles arranged circumferentially about the axis of rotation of the rotating member, wherein each code cycle is associated with a unique position of the rotating member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the rotating member; - and
a first clock sequence positioned circumferentially about the axis of rotation of the rotating member; first means for reading the clock sequence and for reading the code cycles of the code sequence which are brought into instantaneous registration with a monitoring point as the rotating member is rotated, wherein the monitoring point is fixed in position relative to the rotating member; means coupled to the reading means for extracting the position data from the code cycles being read by the reading means in accordance with the clock sequence and for temporarily storing the position data in the order received; and means coupled to the extracting and storing means for converting the consecutive sequence of the N most recently received position data into positional information, wherein the first sequence of code cycles is valid for a first direction of rotation; a second sequence of code cycles which is valid for a direction of rotation which is opposite the first direction of rotation and arranged circumferentially about the axis of rotation of the rotating member, wherein each code cycle is associated with a unique position of the rotating member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the rotating member; a second clock sequence positioned circumferentially about the axis of rotation of the rotating member and in quadrature with respect to the first clock sequence; second means for reading the second clock sequence and for reading the code cycles of the second code sequence which are brought into instantaneous registration with a monitoring point as the rotating member is rotated, wherein the monitoring point is fixed in position relative to the rotating member, and further wherein the second code sequence is supplied to the extracting and storing means; and means coupled to the first and second reading means for determining direction of rotation from the relative transitions of the first and second clock sequences, wherein said determining means controls the extracting and storing means to store position data from the first or second code sequences as a function of the direction of rotation of the rotating member. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An apparatus providing information of the position of a member which moves linearly between a first position and a second position, comprising
code means positioned for movement with the member for providing position data and synchronizing information, including a first sequence of code cycles positioned along the moving member so that the first sequence is translated into registration with a monitoring point that is fixed in relation to the moving member as the member is translated between the first and second positions, wherein each code cycle is associated with a unique position of the member and provides position data, and further wherein the position data from each code cycle, in combination with the position data from adjacent N-1 consecutive code cycles, defines a pattern which is unique from the pattern formed by the position data from any other N consecutive code cycles in the code sequence, so that each N consecutive code cycles identify a unique position of the member wherein the code sequence comprises a series of bits formed by the bits occupying a selected bit position in each of the words in a sequence of N-bit code words the sequence of N-bit code words being formed according to the steps of: -
a. beginning with all N-bits of a first N-bit code word in a first logic state; b. shifting the bits in the first N-bit code word by one bit position so that a bit position is vacated; c. setting the vacated bit position to a second logic state, different from the first logic state, to form a new N-bit code word and assigning the new N-bit code word to the sequence of N-bit code words if the new N-bit code word does not match any of the other N-bit code words in the sequence of N-bit code words; d. setting the vacated bit position to the first logic state to form an alternate N-bit code word and assigning the alternate N-bit code word to the sequence of N-bit code words if the new N-bit code word of step "c" matches any of the outer N-bit code words in the sequence of N-bit code words; and e. repeating steps "b" through "d" until 2N N-bit code words are present in the sequence of N-bit code words, wherein in step "b" the "first N-bit code word" is replaced by the N-bit code word that was assigned to the sequence of N-bit code words in steps "c" and "d"; and a first clock sequence positioned along the moving member so that the first clock sequence is translated into registration with the monitoring point, the clock sequence supplying synchronizing information; first means for reading the clock sequence and for reading the code cycles of the code sequence which are brought into instantaneous registration with the monitoring point as the member is translated between the first and second positions; means coupled to the reading means for extracting the position data from the code cycles being read by the reading means in accordance with the clock sequence and for temporarily storing the position data in the order received; and means coupled to the extracting and storing means for converting the consecutive sequence of the N most recently received position data into positional information. - View Dependent Claims (15)
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Specification