Absolute combinational encoders coupled through a fixed gear ratio
AssigneeRockwell International Corporation
InventorDonald E. Mosier
Life of this patent
Estimating the term…
Abstract
An encoder system and technique is disclosed for providing greater resolution for position indications. The encoder includes multiple small absolute encoders coupled through a fixed gear ratio to provide an increase in the number of positions which may be absolutely resolved by the encoder without a significant increase in the size of the encoder. The resulting configuration produces a size which is the sum of the individual sizes of the multiple encoders but produces a resolution which is proportional to a multiplication of the individual encoder positions. The resulting encoder provides an absolute indication of position without the requirement for knowledge of the previous position or a predetermined rotation prior to position indication.
Claims15
An encoder having improved resolution comprising:
- first means for providing a predetermined number of output position indications, said first means comprising a first absolute encoder having a first predetermined number of output positions N1, where N1=K(M) and K and M are integer.gtoreq.1, where M is a selected one of the integers 1 and 2;
- at least one second means for providing a different predetermined number of output position indications, said second means comprising a second absolute encoder having a second predetermined number of output positions N2 where N2=(N1/M)-1;
- and
- means for coupling said first and second means to one another for providing a predetermined number of combined output position indications proportional to the product of the number of output position indications of said first and second means, said means for coupling including a first gear coupled to drive said first absolute encoder and a second gear coupled to said first gear and coupled to drive said second absolute encoder, said first and second gears having a gear ratio selected to be N1:N2.
A shaft position encoder comprising:
- first means for providing a predetermined first number of absolute output positions N1 in response to movement thereof, where N1=K(M) and K and M are integers.gtoreq.1;
- second means for providing a predetermined second number of absolute output positions N2 in response to movement thereof, where N2=(N1/M)-1;
- means for coupling said first and second means to one another to provide a predetermined number of absolute positions formed by a combination of the output positions from said first and second means which is proportional to the product of the number of absolute output positions of said first and second means, said means for coupling including first and second gear couple to said first and second means, respectively, and having a gear ratio fixed at N1:N2;
- and
- means responsive to a shaft for moving at least one of said first and second means to produce said combination of output positions representing shaft position.
A shaft position encoder comprising:
- first means for providing a predetermined first number of absolute output positions N1 in response to movement thereof, where N1=K(M) and K and M are integers>1;
- second means for providing a predetermiend second number of absolute output positions N2 in response to movement thereof, where N2=(N1/M)-1;
- means for coupling said first and second means to one another to provide a predetermined number of absolute positions formed by a combination of the output positions from said first and second means which is proportional to the product of the number of absolute output positions of said first and second means, said means for coupling including first and second gears coupled to said first and second means, respectively, said first gear having a number of teeth equal to N1 and said second gear having a number of teeth equal to N2, said gears having a gear ratio fixed at N1:N2;
- and
- means responsive to a shaft for moving at least one of said first and second means to produce said combination of output positions representing shaft positions.
In a shaft position encoder having a rotating shaft coupled to an absolute encoder such that for each increment of shaft rotation by a predetermined amount the encoder provides a unique output representing shaft position for that increment, the improvement in the absolute encoder comprising:
- a first absolute encoder providing a first predetermined number of position outputs N1 where N1=K(M) and K and M are integers.gtoreq.1 and M is a selected one of the integers 1 and 2;
- a second absolute encoder providing a second predetermined number of position outputs N2 different from said first encoder, wherein N2=(N1/M)-1;
- and
- means for coupling said first absolute encoder to said second absolute encoder to form an absolute combinational encoder for producing a plurality of unique outputs representing shaft positions, each formed by a combination of one position output from each encoder, and proportional to the product of the number of position outputs of said first and second absolute absolute encoders, said means for coupling a first gear coupled to drive said first encoder and a second gear coupled to said first gear and coupled to drive said second encoder, said first gear having a number of teeth equal to N1 and said second gear having a number of teeth equal to N2, and said first and second gear having a fixed gear ratio N1:N2.
Dependencies are inferred from the claim text.