# US 10,502,593 B1 · Linear and rotary multitrack absolute position encoder and methods using the same

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- Number: US 10,502,593 B1
- Document ID: US10502593B1
- Status: Granted
- Kind: B1
- Application number: 16/433,427
- Filed: 2019-06-06
- Published: 2019-12-12
- Granted: 2019-12-10
- Earliest claimed: 2018-06-07
- Applicants: Philip M. Johnson; David K. Johnson
- Inventors: Philip M. Johnson; David K. Johnson
- Web page: https://patentgrep.com/patent/US10502593B1

## CPC

- G01D 5/34792: {with only digital scales or both digital and incremental scales}
- G01D 5/3473: {Circular or rotary encoders}
- G01D 5/34746: {Linear encoders}
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

Optical Position Encoders and methods using the same are described. In embodiments, the optical position encoders include a multitrack Hybrid Cyclic Binary Code-2 (HCBC-2) encoded scale and an Optical Readout Assembly (ORA), where the ORA provides absolute position optical readout and automatic physical alignment to the scale. Linear optical position encoders, rotary optical position encoders, and methods of measuring the position of ORA relative to a scale using such encoders are also described.

## Claims

### Claim 1

An optical absolute position encoder, comprising:
a scale comprising a substrate comprising a first region encoded with a hybrid cyclic binary code 2 (HCBC-2); and
an optical readout assembly (ORA);
wherein:
said first region encoded with said HCBC-2 comprises:
a first sub-region comprising a first multitrack array of hybrid cyclic binary code (HCBC) patterns;
a second sub-region comprising a second multitrack array of HCBC patterns, the second multitrack array being a reflection and complement of the first multitrack array;
the ORA comprises at least one light source configured to emit light pulses onto said HCBC-2 encoded scale; and
said ORA is configured to measure at least a portion of light reflected by said HCBC-2 scale and determine a position of said HCBC-2 scale relative to said ORA.

### Claim 2 (depends on 1)

The optical absolute position encoder of claim 1, wherein:
said scale comprises a first inner region comprising said first sub-region and a second inner region comprising said second sub-region;
each track of the first multitrack array is an encoded strip that is longer in a measurement direction than in a non-measurement direction.

### Claim 3 (depends on 2)

The optical absolute position encoder of claim 2, wherein:
said scale further comprises a first outer region and a second outer region; and
said first outer region, said second outer region, or both said first and said second outer regions comprise at least one unencoded alignment track.

### Claim 4 (depends on 3)

The optical absolute position encoder of claim 3, wherein said first region is disposed between the first outer region and the second outer region.

### Claim 5 (depends on 4)

The absolute optical position encoder of claim 4, wherein said first and said second outer regions each comprise an unencoded alignment track.

### Claim 6 (depends on 4)

The absolute optical position encoder of claim 4, wherein:
the at least one alignment track comprises a first alignment track pair and a second alignment track pair;
the first outer region comprises the first alignment track pair;
the second outer region comprises the second alignment track pair;
each of the first and second alignment track pairs comprise a first track and a second track adjacent the first track, wherein the first track is non-reflective or non-transmissive over an entire length of the scale; and the second track is reflective or transmissive over the entire length of the scale.

### Claim 7 (depends on 3)

The absolute optical position encoder of claim 3, wherein the ORA comprises an optical sensor array, the optical sensor array comprising:
an array of light sources; and
an array of light sensors.

### Claim 8 (depends on 7)

The absolute optical position encoder of claim 7, wherein the array of light sensors comprises a plurality of confocal optical sensors.

### Claim 9 (depends on 7)

The absolute optical position encoder of claim 7, wherein:
the optical sensor array comprises a readout line assembly comprising at least one readout line;
the at least one readout line comprises a plurality of readout light sources and a plurality of readout line optical sensors;
said array of light sources comprises said plurality of readout light sources; and
said array of light sensors comprises said plurality of said readout line optical sensors.

### Claim 10 (depends on 9)

The absolute optical position encoder of claim 9, wherein the optical sensor array further comprises a plurality of alignment sensors.

### Claim 11 (depends on 9)

The absolute optical position encoder of claim 9, wherein:
said plurality of readout line optical sensors are configured to measure linear position errors most accurately in a first direction;
said plurality of alignment sensors are configured to measure an alignment position in a second direction most accurately; and
the first direction and the second direction differ from one another.

### Claim 12 (depends on 1)

The optical absolute position encoder of claim 1, wherein:
the optical absolute position encoder is a linear optical absolute position encoder; and
said scale is a planar, wherein the first and second multitrack arrays are arranged on or are formed within the substrate in a planar two-dimensional layout.

### Claim 13 (depends on 1)

The optical absolute position encoder of claim 1, wherein:
the optical absolute position encoder is a rotary optical absolute position encoder;
said scale is a rotary scale; and
said substrate is or is disposed on an inside or outside surface of a cylindrical drum.

### Claim 14

A method of measuring the absolute position of a scale relative to a readout assembly, comprising:
emitting light pulses from a light source, said light pulse being incident on a scale, the scale comprising a first region encoded with a hybrid binary cyclic code 2 (HCBC-2);
detecting, with an optical readout assembly (ORA) at least a portion of said light pulses reflected by said scale, and generating at least one sensor signal; and
calculating, with a controller, a position of the scale relative to said readout assembly, based on said at least one sensor signal;
wherein:
the first region encoded with said HCBC-2 scale comprises:
a first sub-region comprising a first multitrack array of hybrid cyclic binary code (HCBC) patterns; and
a second sub-region comprising a second multitrack array of HCBC patterns, the second multitrack array being a reflection and complement of the first multitrack array.

### Claim 15 (depends on 14)

The method of claim 14, wherein:
said scale comprises a first inner region comprising said first sub-region and a second inner region comprising said second sub-region;
each track of the first multitrack array is an encoded strip that is longer in a measurement direction than in a non-measurement direction.

### Claim 16 (depends on 15)

The method of claim 15, wherein:
said scale further comprises a first outer region and a second outer region; and
said first outer region, said second outer region, or both said first and said second outer regions comprise at least one unencoded alignment track.

### Claim 17 (depends on 16)

The method of claim 16, wherein said first and said second outer regions each comprise an unencoded alignment track.

### Claim 18 (depends on 16)

The method of claim 16, wherein the ORA comprises an optical sensor array, the optical sensor array comprising:
an array of light sources configured to emit said light pulses; and
an array of light sensors configured to detect light reflected by said scale.

### Claim 19 (depends on 18)

The method of claim 18, wherein the array of light sensors comprises a plurality of confocal optical sensors.

### Claim 20 (depends on 18)

The method of claim 18, wherein:
the optical sensor array comprises a readout line assembly comprising at least one readout line;
the at least one readout line comprises a plurality of readout light sources and a plurality of readout line optical sensors;
said array of light sources comprises said plurality of readout light sources; and
said array of light sensors comprises said plurality of said readout line optical sensors.

### Claim 21 (depends on 14)

The method of claim 14, wherein said at least one sensor signal comprises a plurality of sensor signals, and the method further comprises:
measuring said plurality of sensor signals;
generating a reference signal value from said plurality of sensor signals; and
normalizing each of the plurality of sensor signals with the reference signal value to generate a plurality of normalized sensor signals; and
wherein calculating said position of the scale relative to said readout assembly is performed based on said plurality of normalized sensor signals.