Abstract: An encoder having a code scale, an illumination system, and a plurality of photodetectors is disclosed. The code scale has a plurality of tracks that are illuminated by the illumination system. Each photodetector receives light from a corresponding one of the tracks and generates a signal indicative of a quantity of light received from that track. Each photodetector is limited to detecting light in a band of wavelengths corresponding to that track. Each track generates light in a band of wavelengths corresponding to that track, and the band of wavelengths corresponding to one of the tracks is different from the band of wavelengths corresponding to the tracks that are next to that track. The tracks can include alternating reflective and absorptive stripes, alternating transmissive and reflective stripes, or alternating luminescent and absorptive stripes.

Abstract: An encoder having a code scale, an illumination system, and a plurality of photodetectors is disclosed. The code scale has a plurality of tracks that are illuminated by the illumination system. Each photodetector receives light from a corresponding one of the tracks and generates a signal indicative of a quantity of light received from that track. Each photodetector is limited to detecting light in a band of wavelengths corresponding to that track. Each track generates light in a band of wavelengths corresponding to that track, and the band of wavelengths corresponding to one of the tracks is different from the band of wavelengths corresponding to the tracks that are next to that track. The tracks can include alternating reflective and absorptive stripes, alternating transmissive and reflective stripes, or alternating luminescent and absorptive stripes.

Abstract: An encoder having a code scale, an illumination system, and a plurality of photodetectors is disclosed. The code scale has a plurality of tracks that are illuminated by the illumination system. Each photodetector receives light from a corresponding one of the tracks and generates a signal indicative of a quantity of light received from that track. Each photodetector is limited to detecting light in a band of wavelengths corresponding to that track. Each track generates light in a band of wavelengths corresponding to that track, and the band of wavelengths corresponding to one of the tracks is different from the band of wavelengths corresponding to the tracks that are next to that track. The tracks can include alternating reflective and absorptive stripes, alternating transmissive and reflective stripes, or alternating luminescent and absorptive stripes.

Abstract: An optical encoder includes a code strip having a first side, a second side, a first track comprising indicia thereon, and a second track comprising indicia thereon. The code strip is moveable along a displacement path with respect to the optical encoder. A light source positioned on the first side of the code strip directs light toward the code strip. A first detector element is positioned on the second side of the code strip and is generally aligned with the first track of the code strip. A second detector element is positioned on the second side of the code strip and is generally aligned with the second track of the code strip. The second detector element is also positioned so that the second detector element is located a spaced distance along the displacement path from the first detector element.

Abstract: An interpolating detector for generating a position signal indicating a change in the relative position of a code pattern that includes alternating light and dark stripes is disclosed. The interpolating detector includes a photodiode array, an interpolation function generator, a detector function generator, and a cross-point detector. The photodiode array includes a plurality of sets of photodetectors that generate sinusoidal signals having different amplitudes and phases. The interpolation function generator generates first and second interpolation functions, I1(x)=f1 cos(x) and I2(x)=f2 sin(x), respectively, from the photodiode signals. The detector function generator generates 4 detector signals, D1(x)-D4(x), from the photodiode signals. The cross-point detector generates a transition signal when I1(x) crosses D1 or D3 or when I2(x) crosses D2 or D4.

Abstract: An optical encoder includes a code strip having a first side, a second side, a first track comprising indicia thereon, and a second track comprising indicia thereon. The code strip is moveable along a displacement path with respect to the optical encoder. A light source positioned on the first side of the code strip directs light toward the code strip. A first detector element is positioned on the second side of the code strip and is generally aligned with the first track of the code strip. A second detector element is positioned on the second side of the code strip and is generally aligned with the second track of the code strip. The second detector element is also positioned so that the second detector element is located a spaced distance along the displacement path from the first detector element.

Abstract: A Low-Cost Absolute Linear Optical Encoder (“LALOE”) for determining the absolute position of a read-head within the LALOE relative to a codestrip is disclosed. The LALOE may include an emitter module within the read-head, the emitter module having a plurality of light sources arranged in an light source pattern and a 90° Out-Of-Phase light source; and a detector module within the read-head, the detector module having a plurality of photo-detectors arranged in a photo-detector pattern corresponding to the light source pattern and a 90° Out-Of-Phase photo-detector corresponding to the 90° Out-Of-Phase light source.