US4899048A
Expired / Lapsed
US
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Focused optical beam encoder of position
Assignee: Printware Inc
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Filing: 1987-04-27
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Granted: 1990-02-06
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Expires: 2007-04-27
Abstract
Abstract A light beam, typically 780 nanometer coherent light generated by a laser diode, is focused, preferably by a wide angle graded index optics lens having a numerical aperture of 0.46 and a diameter of 1.8 mm, into a diffraction limited spot, of approximate diameter 0.039 to 0.3 mils, upon an encoder wheel. The encoder wheel is typically a photoetched radial reticular grating on Mylar® plastic having lines at 0.00025" width at a radius of 1". The focused light beam intercepts the encoder wheel at this 1" radius and is alternately transmitted and obstructed by the reticular grating of the rotating encoder wheel. The selectivity transmitted light beam is received at a detector, typically a phototransistor. Greater than 10,000 transitions per encoder wheel revolution are detectable.
Inventors
- 👤 David J. Shelander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:17
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/347; G01D5/34707; G01D5/34715
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
91 words
In an optical position encoder having a source of light, a detector of light from the source of light, and a grating which moves relative to a path of light between the source and the detector in order to, by such movement, selectively interrupt the light path between source and detector so that the motion of the grating may be detected by these interruptions, an improvement comprising: a focusing means between the source of light and the grating for convergently focusing the light from the source of light onto the grating.
Claim 2
Dependent Claim
91 words
In an optical position encoder having a source of light, a detector of light from the source of light, and a grating which moves relative to a path of light between the source and the detector in order to, by such movement, selectively interrupt the light path between source and detector so that the motion of the grating may be detected by these interruptions, an improvement comprising: a focusing means between the source of light and the grating for convergently focusing the light from the source of light onto the grating.
Claim 3
Dependent Claim
29 words
The improvement to an optical position encoder according to claim 1 wherein the focusing means is focusing the source of light into a diffraction limited spot at the grating.
Claim 4
Dependent Claim
39 words
The improvement to an optical position encoder according to claim 1 wherein the focusing means comprises: a lens with an index of refraction which decreases as the square of the radial distance from an optical axis of the lens.
Claim 5
Dependent Claim
21 words
The improvement to an optical position encoder according to claim 1 wherein the focusing means comprises: a graded index optics lens.
Claim 6
Dependent Claim
22 words
The improvement to an optical position encoder according to claim 1 wherein the source of light comprises: a source of coherent light.
Claim 7
Dependent Claim
21 words
The improvement to an optical position encoder according to claim 5 wherein the source of light comprises: a semiconductor laser diode.
Claim 8
Dependent Claim
14 words
The improvement according to claim 1 wherein the detector of light comprises: a phototransistor.
Claim 9
Dependent Claim
28 words
The improvement according to claim 1 wherein the grating is an optically encoded disk, and wherein the focusing means is focusing light onto the plane of the disk.
Claim 10
Dependent Claim
91 words
In an optical encoder of angular position having a light source, a light sensor, and an encoder wheel positioned between the light source and light sensor and presenting a pattern of alternating segments which, with angular positional movement of the encoder wheel, alternately enable and disable a light path between the light source and the light sensor and make the light sensor detect the angular positional movement of the encoder wheel, an improvement comprising: a lens convergently focusing light from the source of light onto the plane of the encoder wheel.
Claim 11
Dependent Claim
91 words
In an optical encoder of angular position having a light source, a light sensor, and an encoder wheel positioned between the light source and light sensor and presenting a pattern of alternating segments which, with angular positional movement of the encoder wheel, alternately enable and disable a light path between the light source and the light sensor and make the light sensor detect the angular positional movement of the encoder wheel, an improvement comprising: a lens convergently focusing light from the source of light onto the plane of the encoder wheel.
Claim 12
Dependent Claim
23 words
The improvement to an optical encoder of angular position according to claim 9 wherein the lens further comprises: a graded index optics lens.
Claim 13
Dependent Claim
31 words
The improvement to an optical encoder of angular position according to claim 9 wherein the lens is focusing light to a diffraction limited spot at the plane of the decoder wheel.
Claim 14
Dependent Claim
85 words
An improved method of optically encoding positional information by interrupting an optical beam between a source of light and a light sensor with and by a grating having a pattern of segments alternately enabling and disabling communication of light between the source and the sensor dependent upon the position of the grating relative thereto so that detection of the interruptions of the optical beam by the sensor is indicative of position of the grating, the improved method comprising: convergently focusing the light onto the grating.
Claim 15
Dependent Claim
85 words
An improved method of optically encoding positional information by interrupting an optical beam between a source of light and a light sensor with and by a grating having a pattern of segments alternately enabling and disabling communication of light between the source and the sensor dependent upon the position of the grating relative thereto so that detection of the interruptions of the optical beam by the sensor is indicative of position of the grating, the improved method comprising: convergently focusing the light onto the grating.
Claim 16
Dependent Claim
29 words
The improved method for optically encoding positional information according to claim 12 wherein the focusing of light is of coherent light into a diffraction limited spot on the grating.
Claim 17
Dependent Claim
19 words
The improved method of optically encoding positional information according to claim 12 wherein the focusing is by a lens.
Claim 18
Dependent Claim
36 words
The improved method of optically encoding positional information according to claim 14 wherein the focusing is by a lens with an index of refraction which decreases as the square of the distance from the optical axis.
Claim 19
Dependent Claim
22 words
The improved method of optically encoding positional information according to claim 14 wherein the focusing is by a graded index optics lens.
Claim 20
Dependent Claim
109 words
The improved method of optically encoding positional information according to claim 12 wherein the source of light is a source of coherent light; wherein the grating is an optically encoded disk having alternate opaque and translucent segments; wherein the communication of light between the source and the sensor is through the disk; and wherein the focusing is onto the grating of the plane of the disk at a focal point diameter which is within two times of the diffraction limited diameter equalling 4 f/D wherein=the wavelength of the coherent light, f=the focal length of the focusing, and D=the diameter of the coherent light beam which is intercepted for focusing.
Claim 21
Independent Claim
277 words
A method of aligning components of an optical position encoder in order that an optical disk bearing greater than 1000 reticule lines per inch may be reliably resolved, the method comprising: defining the plane of an optical disk, locating, in a line orthogonal to the plane of the disk within plus or minus four degrees and intersecting the disk at a radius whereat greater than 1000 reticule lines per inch are present upon the disk, a semiconductor laser upon one side of the disk; locating, upon the line between the semiconductor laser and the disk, a graded index optic lens at (i) a distance from the semiconductor laser which intercepts substantial light and (ii) a distance from the disk so that a spot of size approximately the size of a diffraction limited spot is focused at the plane of the disk, ergo a spot of diameter D=4λf/πD wherein λ=wavelength of the semiconductor laser, while D=beam diameter intercepted by the graded index optic lens, and f=focal length of the graded index optic lens; adjusting λ, D, and f so that D is less than 1 mil; and locating the light sensor at a distance from the spot focus upon the disk so that substantial of the light passing through the spot is intercepted; whereby the light sensor is detecting light from the semiconductor laser which, by focusing action of the graded index optic lens, has intercepted the plane of the disk at a spot less than 1 mil diameter, of which spots there are greater than 1000/1=1000 in one inch; whereby resolution of greater than 1000 reticule lines per inch on the optical disk may be reliably resolved.
Claim 22
Independent Claim
277 words
A method of aligning components of an optical position encoder in order that an optical disk bearing greater than 1000 reticule lines per inch may be reliably resolved, the method comprising: defining the plane of an optical disk, locating, in a line orthogonal to the plane of the disk within plus or minus four degrees and intersecting the disk at a radius whereat greater than 1000 reticule lines per inch are present upon the disk, a semiconductor laser upon one side of the disk; locating, upon the line between the semiconductor laser and the disk, a graded index optic lens at (i) a distance from the semiconductor laser which intercepts substantial light and (ii) a distance from the disk so that a spot of size approximately the size of a diffraction limited spot is focused at the plane of the disk, ergo a spot of diameter D=4λf/πD wherein λ=wavelength of the semiconductor laser, while D=beam diameter intercepted by the graded index optic lens, and f=focal length of the graded index optic lens; adjusting λ, D, and f so that D is less than 1 mil; and locating the light sensor at a distance from the spot focus upon the disk so that substantial of the light passing through the spot is intercepted; whereby the light sensor is detecting light from the semiconductor laser which, by focusing action of the graded index optic lens, has intercepted the plane of the disk at a spot less than 1 mil diameter, of which spots there are greater than 1000/1=1000 in one inch; whereby resolution of greater than 1000 reticule lines per inch on the optical disk may be reliably resolved.
Claim 23
Dependent Claim
99 words
In a machine tool, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 24
Dependent Claim
99 words
In a machine tool, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 25
Dependent Claim
98 words
In a robot, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 26
Dependent Claim
98 words
In a robot, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 27
Dependent Claim
99 words
In a computer peripheral, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 28
Dependent Claim
99 words
In a computer peripheral, an encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 29
Dependent Claim
106 words
In a machine variably positioning a workpiece, an encoder of the variable position at which the machine positions the workpiece comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 30
Dependent Claim
106 words
In a machine variably positioning a workpiece, an encoder of the variable position at which the machine positions the workpiece comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and a lens for convergently focusing light from the source of light onto the optical grating.
Claim 31
Dependent Claim
90 words
An optical encoder of angular position comprising: a light source, a light sensor, and an encoder wheel positioned between the light source and light sensor and presenting a pattern of alternating segments which, with angular positional movement of the encoder wheel, alternately enable and disable a light path between the light source and the light sensor and make the light sensor detect the angular positional movement of the encoder wheel; and a lens means for convergently focusing light from the source of light onto the plane of the encoder wheel.
Claim 32
Dependent Claim
90 words
An optical encoder of angular position comprising: a light source, a light sensor, and an encoder wheel positioned between the light source and light sensor and presenting a pattern of alternating segments which, with angular positional movement of the encoder wheel, alternately enable and disable a light path between the light source and the light sensor and make the light sensor detect the angular positional movement of the encoder wheel; and a lens means for convergently focusing light from the source of light onto the plane of the encoder wheel.
Claim 33
Dependent Claim
95 words
An encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and focusing means for convergently focusing light from the source of light onto the optical grating.
Claim 34
Dependent Claim
95 words
An encoder of position and/or time derivatives of position comprising: a source of light; a detector of light from the source of light; an optical grating which moves relative to a path of light between the source of light and the detector of light in order, by this movement, to selectively interrupt the light path between the source of light and the detector of light so that the movement of the grating is detected by the detector of light; and focusing means for convergently focusing light from the source of light onto the optical grating.
Claim 35
Dependent Claim
86 words
An optical position encoder comprising: a source of light; a detector of light from the source of light; a grating which moves relative to a path of light between the source and the detector in order to, by such movement, selectively interrupt the light path between source and detector so that the motion of the grating may be detected by these interruptions; and a focusing means between the source of light and grating for convergently focusing the light from the source of light onto the grating.
Claim 36
Dependent Claim
86 words
An optical position encoder comprising: a source of light; a detector of light from the source of light; a grating which moves relative to a path of light between the source and the detector in order to, by such movement, selectively interrupt the light path between source and detector so that the motion of the grating may be detected by these interruptions; and a focusing means between the source of light and grating for convergently focusing the light from the source of light onto the grating.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-05 | 1993-08-07 | 1994-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-05 | 1997-08-07 | 1998-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-05 | 2001-08-07 | 2002-02-06 | $7700.00 | Window Closed / Lapsed |