Digital encoder and position reference

Claim 2

In a digital encoder and position reference apparatus for indicating the position of a movable element relative to a fixed element and including a pickup head having a plurality of magnetic flux sensing means, a digital readout box operatively connected to said pickup head and adapted to convert a binary coded signal from said sensing mEans to a decimal equivalent: the improvement comprising a scale located adjacent to said sensing means, said scale including an elongated base, a plurality of generally parallel channels extending along the major axis of said base, one of said channels being in proximity to each of the sensing means of the pickup head, each of said channels having multiple magnetized and non-magnetized areas, said magnetized areas adapted to emit concentrated magnetic flux lines in predetermined directions, the magnetized areas of said channels being arranged to indicate a different binary coded word for each position along the entire length of said scale, and the magnetized areas of adjacent channels having opposed polarity so that the north-seeking pole of one channel will be adjacent to the north-seeking pole of an adjacent channel, and the southseeking pole of said one channel will be adjacent to the southseeking pole of another adjacent channel, whereby the magnetic flux field of each magnetized area will be located adjacent to that area only.

Claim 3

A digital encoder and position reference for indicating the position of a movable element relative to a fixed element comprising a scale having a binary coded pattern fixed to one of said elements, said pattern including a plurality of spaced elongated generally parallel channels, each of said channels including alternate magnetized and non-magnetized areas, each of said magnetized areas having a first magnetic pole along one lateral edge and a second magnetic pole along the opposite lateral edge, said edges being parallel to the length of the channel, adjacent channels being magnetized in opposite directions so that the magnetic poles on opposing sides of any inter-channel gap are of the same magnetic polarity, each magnetized area emitting concentrated magnetic flux lines in predetermined directions, said magnetized and non-magnetized areas in said channels indicating a different binary coded word for each position along the entire length of said scale, a pickup head mounted on the other of said elements and disposed in close proximity to said scale, said pickup head including a flux sensitive sensing element for each channel of said scale, means for conducting magnetic flux from opposite sides of each channel to the corresponding sensing element, and means operatively connected to said pickup head for utilizing the coded signal, whereby the position of said movable element relative to said fixed element is determined.

Claim 4

A digital encoder and position reference for indicating the position of a movable element relative to a fixed element comprising a scale having a binary coded pattern fixed to one of said elements, said pattern including a plurality of spaced elongated generally parallel channels, each of said channels including alternate magnetized and non-magnetized areas, each of said magnetized areas having a first magnetic pole along one lateral edge and a second magnetic pole along the opposite lateral edge, said edges being parallel to the length of the channel, adjacent channels being magnetized in opposite directions so that the magnetic poles on opposing sides of any inter-channel gap are of the same magnetic polarity, each magnetized area emitting concentrated magnetic flux lines in predetermined directions, said magnetized and non-magnetized areas in said channels indicating a different binary coded word for each position along the entire length of said scale, a pickup head mounted on the other of said elements and disposed in close proximity to said scale, said pickup head including a flux sensitive sensing element for each channel of said scale, means for conducting magnetic flux from opposite sides of each channel to the corresponding sensing element, and means operatively connected to said pickup head for utilizing the coded signal, whereby the position of said movable element relative to said fixed element is determined.

Claim 5

The structure of claim 2 in which said scale is a photo-etched pattern in which each channel includes alternate bits of magnetizable and non-magnetizable materials.

Claim 6

The structure of claim 3 including means on both sides of said pickup head for magnetizing and demagnetizing said magnetizable material.

Claim 7

The structure of claim 2 in which said scale includes a layer of magnetizable material and in which each of said channels includes alternate magnetized and non-magnetized areas.

Claim 8

The structure of claim 2 in which said sensing element includes a magnetoresistor.

Claim 9

The structure of claim 2 in which said pickup head is disposed generally normal to the major axis of said scale.

Claim 10

The structure of claim 2 in which said pickup head is disposed at an angle less than 90* to the major axis of said scale and each of said magnetized areas terminates in an edge parallel to said pickup head.

Claim 11

The structure of claim 2 in which said scale includes an uncoded strip adjacent to said coded pattern, and said pickup head includes a combination read-write portion disposed in proximity to said uncoded strip so that additional indicia can be selectively applied to said scale.

Claim 12

The structure of claim 2 in which said scale includes at least two channels of indicia in which the pattern of indicia in one channel is offset from the pattern in the other channel, means for combining the information sensed from said two channels to create a basic reference signal, means for electronically comparing fractional pOrtions of said basic signal with the signal from one of said channels, whereby the location of said sensing element relative to said scale is determined to a resolution greater than that represented by the closest spacing of the magnetized areas in any channel of said scale.

Claim 13

The structure of claim 2 in which said means for conducting magnetic flux to each of said sensing elements includes a pair of spaced pole pieces, each of said pole pieces having a first portion engaging said sensing element and a second portion located adjacent to the associated channel, and said second portion of each of the pole pieces of the pickup head being disposed along a single common straight edge.

Claim 14

The structure of claim 11 in which at least one of said pole pieces is offset relative to the other.