Shaft position encoder
First Claim
1. A shaft position encoder comprising:
- an input shaft;
a high-speed disc coupled to the input shaft;
at least one group of n concentric tracks on the high-speed disc, n being greater than one, each track comprising slotted openings that form alternating transparent and opaque sectors;
n+1 pairs of light sources and light sensors associated with each group of tracks, the light sources and light sensors being disposed on opposite sides of the high-speed disc in alignment with respective tracks such that two pairs are aligned with one of the tracks;
a low-speed disc means coupled to the input shaft with a speed reduction of 1;
2n relative to the high-speed disc;
a group of n concentric tracks on the low-speed disc means, each track comprising slotted openings that form alternating transparent and opaque sectors; and
n+1 pairs of light sources and light sensors associated with the group of tracks on the low-speed disc means, the sources and sensors being disposed on opposite sides of the low-speed disc means in alignment with the respective tracks such that two pairs are aligned with one of the tracks thereon.
3 Assignments
0 Petitions
Accused Products
Abstract
A multi-turn shaft position encoder employs a plurality of encoder discs with successive speed reductions of 1:2n and the generation of n+1 bits of binary data representative of the angular position of the respective discs as the input shaft rotates. Specifically, a high-speed disc is coupled to an input shaft and low-speed disc means is coupled to the input shaft with a speed reduction of 1:2n relative to the high-speed disc. At least one group of n+1 bits of binary data representative of the angular position of the high-speed disc are generated as the input shaft rotates. A group of n+1 bits of data representative of the angular position of the low-speed disc means is generated as the input shaft rotates. Thus, the low-speed disc is divided in to 2n units per revolution but produces 2n+1 bits of data. The data is generated by the encoder in unit distance code and is then converted into fewer bits of data in natural binary code. The encoder has a high-speed disc in connection with which two groups of data bits are generated, one being shifted relative to the other. In addition, there is cumulative bit shifting from disc to disc. The n+1st bit is generated on the same track of each encoder disc as the nth bit by placing the corresponding data bit-generating sensors at angularly spaced apart positions relative to the same track.
35 Citations
25 Claims
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1. A shaft position encoder comprising:
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an input shaft; a high-speed disc coupled to the input shaft; at least one group of n concentric tracks on the high-speed disc, n being greater than one, each track comprising slotted openings that form alternating transparent and opaque sectors; n+1 pairs of light sources and light sensors associated with each group of tracks, the light sources and light sensors being disposed on opposite sides of the high-speed disc in alignment with respective tracks such that two pairs are aligned with one of the tracks; a low-speed disc means coupled to the input shaft with a speed reduction of 1;
2n relative to the high-speed disc;a group of n concentric tracks on the low-speed disc means, each track comprising slotted openings that form alternating transparent and opaque sectors; and n+1 pairs of light sources and light sensors associated with the group of tracks on the low-speed disc means, the sources and sensors being disposed on opposite sides of the low-speed disc means in alignment with the respective tracks such that two pairs are aligned with one of the tracks thereon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A shaft position encoder comprising:
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an input shaft; a high-speed disc coupled to the input shaft; low-speed disc means coupled to the input shaft with a speed reduction of 1;
2n relative to the high-speed disc, n being greater than one;first means for generating at least one group of n+1 bits of binary data representative of the angular position of the high-speed disc as the input shaft rotates; and second means for generating a group of n+1 bits of data representative of the angular position of the first low-speed disc means as the input shaft rotates. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A shaft encoder comprising:
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an input shaft; a high-speed disc coupled to the input shaft; first low-speed disc means coupled to the input shaft with a speed reduction relative to the high-speed disc; second low-speed disc means coupled to the input shaft with a speed reduction relative to the first low-speed disc means; means for generating at least one group of n+1 bits of binary data in a scale representative of the angular position of the high-speed disc as the input shaft rotates, n being greater than one; means for generating a group of n+1 bits of data in a succeeding scale representative of the angular position of the first low-speed disc means as the input shaft rotates; and means for generating a group of n+1 bits of data in a succeeding scale representative of the angular position of the second low-speed disc means as the input shaft rotates, each group of bits of data comprising n bits of data representative of input shaft position in unit distance code sequence and an n+1st bit shifted a fraction of scale relative to the nth bit, the n+1st bit of each scale and the n bits of the succeeding scale being shifted the same amount so the bit shifting is cumulative from scale to scale.
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23. A shaft encoder comprising:
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an input shaft; a high-speed disc coupled to the input shaft; low-speed disc means coupled to the input shaft with a speed reduction relative to the high-speed disc; means for generating a first group of n+1 bits of binary data representative of the angular position of the high-speed disc as the input shaft rotates, n being greater than one, the scale of the first group being 1/2n divided into 2n+1 units of the high-speed disc; means for generating a second group of n+1 bits of data representative of the angular position of the high-speed disc as the input shaft rotates, the scale of the second group being one revolution of the high-speed disc divided into 2n units; and means for generating a group of bits of data representative of the angular position of the low-speed disc means as the input shaft rotates.
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24. A shaft encoder comprising:
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an input shaft; a plurality of m discs coupled to the input shaft with successive speed reductions; means for generating at least m groups of n+1 bits of binary data representative of the angular positions of the respective discs in unit distance code as the input shaft rotates, in being greater than one and the number of groups being greater than two; and means for converting the data generated by the generating means into m·
n+1 bits of data in natural binary code. - View Dependent Claims (25)
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Specification