Mitutoyo Corporation

Daniel John Kapner

Casey Edward Emtman

Michelle Mary Milvich

Brynn Kristen Hickman MacCoy

Brynn Kristen Hickman Maccoy

A light source array used in illumination portions for optical encoders comprising an illumination portion, a scale grating extending along a measuring direction and receiving light from the illumination portion, and a detector configuration. The light source array comprises individual sources arranged in a grid pattern and coinciding with two transverse sets of parallel grid pattern lines that have two different grid line pitches between their parallel lines. Different instances of the light source array may be mounted with different rotational orientations about an axis normal to the grid pattern, for use in different illumination portions adapted for use with respective scale gratings having different grating pitches along the measuring axis direction. By using the different respective rotational orientations, the individual sources are aligned along respective illumination source lines that are spaced apart by different respective illumination source line pitches along the measuring axis direction.

Light source array used in an illumination portion of an optical encoder

An electronic absolute position encoder comprises a scale, a detector and a signal processing configuration. The scale comprises a signal modulating scale pattern including a first periodic pattern component having a spatial wavelength &#x3bb;, and a second periodic pattern component having a spatial wavelength &#x3bb;. The detector comprises a set of first wavelength sensing elements comprising a first filtering subset of first wavelength sensing elements and a second filtering subset of first wavelength sensing elements including complementary pairs of sensing elements spaced apart by an integer number times 180 degrees of the spatial wavelength &#x3bb;. The detector comprises a set of second wavelength sensing elements comprises a first filtering subset of second wavelength sensing elements and a second filtering subset of second wavelength sensing elements including complementary pairs of sensing elements spaced apart by an integer number times 180 degrees of the spatial wavelength &#x3bb;.

Electronic absolute position encoder

A device for measuring relative displacement between two members includes a scale grating and an optical encoder readhead comprising a first wavelength light source illuminating the grating. The grating outputs scale light to form a moving periodic intensity pattern at the first wavelength. The readhead comprises a plurality of spatial phase detectors comprising: a periodic spatial filter; a phosphor layer that receives light arising from the first wavelength periodic intensity pattern and outputs second wavelength light, and a photodetector element that receives, and is sensitive to, the second wavelength light. The photodetector element inputs second wavelength light corresponding to a spatially filtered version of the first wavelength periodic intensity pattern and outputs a signal indicative of its spatial phase relative to that spatial phase detector. The spatial filtering may be provided by a mask element, or by a pattern of the phosphor layer and/or the detector element, in various embodiments.

Optical encoder readhead configuration with phosphor layer

An encoder configuration comprises a dual-modulation scale track pattern that provides a first intensity modulation component for producing periodic signals, and a second intensity modulation component for producing a long-range absolute signal. The dual-modulation scale track pattern increases the range-to-resolution ratio of the encoder without the use of additional scale tracks that would increase the width of the encoder components. The long-range signal may be encoded in the dual-modulation scale track pattern either by varying certain dimensions of pattern elements included in the scale track or by superimposing a layer including an optical density variation along on the track on pattern elements of similar areas. In either case, the net offset and/or amplitude levels of the associated signals are modified along the scale track. These modified offset and/or amplitude levels provide the basis for the long-range absolute signal.

Absolute optical encoder with long range intensity modulation on scale

A position sensing optical encoder includes an illumination source that operates by providing primary radiation having a first level of intensity uniformity to saturate at least a portion of a relatively broad phosphor area including uniformly distributed phosphor. The phosphor area absorbs the primary radiation and emits phosphor radiation to illuminate the encoder scale pattern. The scale pattern spatially modulates the phosphor light, and the spatially modulated pattern of phosphor light is sensed by a photodetector arrangement. Due at least partially to saturation of the phosphor, the phosphor light has a second level of phosphor light intensity uniformity that is more uniform than the first level of primary light intensity uniformity, which enhances the encoder accuracy. The uniform phosphor illumination intensity is economically provided over a broad area with few components and minimized optical path length, particularly for path length perpendicular to the scale.

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Seattle, WA, United States of America

Daniel John Kapner