US3791037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Linear encoder
Assignee: MOTION SYSTEMS COMPANY Inc
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Filing: 1972-02-17
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Granted: 1974-02-12
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Expires: 1992-02-17
Abstract
Abstract A linear encoder for precisely measuring distances along a measurement axis. One end of a flexible measuring tape is attached to an object, the movement of which is to be measured. The remainder of the measuring tape is wound in a helical configuration around a precise measuring cylinder. One central shaft supports the cylinder for rotational movement. The central shaft rotates with the measuring cylinder, and also supports for rotation a rotary encoder disc plate and a second cylinder which forms part of a constant torque spring motor. Movement of the measured object along the measurement axis results in the measuring tape being either drawn off or wound upon the measuring cylinder. This causes rotation of the measuring cylinder on the central shaft which in turn causes rotation of the encoder disc plate. A reading station adjacent to the encoder plate produces a digital output signal indicative of rotational movement of the encoder plate which is in turn indicative of movement of the measured object along the measurement axis. The constant torque spring motor maintains the measuring tape under constant tension.
Inventors
- 👤 Ciaccio J Di
- 👤 J Gjertsen
- 👤 A Nathanson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:41
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/347; G01D5/3473; G01B; G01B3/00; G01B3/10; G01B3/1061; G01B3/1069; G01B3/1084; Y; Y10; Y10S; Y10S277/00; Y10S277/91
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
412 words
Linear encoder apparatus for measuring a distance along a measuring axis and comprising: a. a support body; b. a central shaft mounted on said support body for rotation about a rotational axis approximately orthogonal to said measuring axis; c. a measuring cylinder mounted on said central shaft for rotation therewith; d. a measuring tape wrapped in a helical configuration around the periphery of said measuring cylinder; e. an encoding member mounted on said central shaft for rotation therewith; f. a reading station mounted adjacent to said encoding member for reading out relative movement between said encoding member and said reading station, and for producing a signal representative of that movement; g. torque means for exerting a torque on said central shaft to maintain said measuring tape under tension as said measuring tape is drawn off or wound upon said measuring cylinder; h. a protective housing assembly extending along said measuring axis for protecting said measuring tape against contamination from dirt and other particles as said measuring tape is drawn off said measuring cylinder; i. a slider element mounted for linear movement along the length of and inside said protective housing assembly, said slider element being attached to one end of said measuring tape; j. said protective housing assembly including a slot located along its length for providing for coupling between said slider element and the measured object; k. a coupling means extending from said slider element through said slot for attachment to the measured object such that linear movement of the measured object causes a corresponding linear movement of said slider element; and l. said protective housing assembly including a linear sealing means along said slot for preventing the entrance of contaminants or dirt into the protective housing assembly, said linear sealing means including two grooves in said protective housing assembly with one groove running along each side of said slot, and further including a long resilient pliable seal inserted into each groove and running along the length of said protective housing, each long pliable seal initially having a cross sectional area larger than that of the corresponding groove, each seal being inserted into each groove by stretching the seal to reduce the cross sectional area of the seal until it is smaller than that of the groove, introducing the stretched seal along the length of the groove, and then allowing the seal to retract in place in the groove in the protective housing assembly to be frictionally held by said groove.
Claim 2
Dependent Claim
412 words
Linear encoder apparatus for measuring a distance along a measuring axis and comprising: a. a support body; b. a central shaft mounted on said support body for rotation about a rotational axis approximately orthogonal to said measuring axis; c. a measuring cylinder mounted on said central shaft for rotation therewith; d. a measuring tape wrapped in a helical configuration around the periphery of said measuring cylinder; e. an encoding member mounted on said central shaft for rotation therewith; f. a reading station mounted adjacent to said encoding member for reading out relative movement between said encoding member and said reading station, and for producing a signal representative of that movement; g. torque means for exerting a torque on said central shaft to maintain said measuring tape under tension as said measuring tape is drawn off or wound upon said measuring cylinder; h. a protective housing assembly extending along said measuring axis for protecting said measuring tape against contamination from dirt and other particles as said measuring tape is drawn off said measuring cylinder; i. a slider element mounted for linear movement along the length of and inside said protective housing assembly, said slider element being attached to one end of said measuring tape; j. said protective housing assembly including a slot located along its length for providing for coupling between said slider element and the measured object; k. a coupling means extending from said slider element through said slot for attachment to the measured object such that linear movement of the measured object causes a corresponding linear movement of said slider element; and l. said protective housing assembly including a linear sealing means along said slot for preventing the entrance of contaminants or dirt into the protective housing assembly, said linear sealing means including two grooves in said protective housing assembly with one groove running along each side of said slot, and further including a long resilient pliable seal inserted into each groove and running along the length of said protective housing, each long pliable seal initially having a cross sectional area larger than that of the corresponding groove, each seal being inserted into each groove by stretching the seal to reduce the cross sectional area of the seal until it is smaller than that of the groove, introducing the stretched seal along the length of the groove, and then allowing the seal to retract in place in the groove in the protective housing assembly to be frictionally held by said groove.
Claim 3
Dependent Claim
103 words
Apparatus as set forth in claim 1 wherein: a. said linear encoder is constructed in a modular manner with two major assemblies as components, a measuring assembly and said protective housing assembly; and b. said measuring assembly includes an external housing which functions as said support body and which houses said central shaft, said measuring cylinder with said measuring tape wrapped around said measuring cylinder, said encoder disc plate, said reading station and said torque means, whereby the modular construction allows protective housing assemblies of different lengths to be fitted to said measuring assembly depending upon the particular requirements of a measuring situation.
Claim 4
Dependent Claim
96 words
Apparatus as set forth in claim 2 wherein: a. said central shaft is mounted for rotation in said external housing by a support bracket; b. a mounting means mounts said support bracket to said external housing; and c. said mounting means includes means for allowing slight rotations of said support bracket relative to said externaL housing about an axis substantially orthogonal to said measuring axis and the axis of said shaft such that said central shaft may be rotated relative to said measuring axis, whereby the scale factor of said linear encoder may be conveniently adjusted.
Claim 5
Dependent Claim
108 words
Apparatus as set forth in claim 3 wherein said mounting means includes first and second screw members extending through said external housing and into said support bracket, said first screw member allowing said support bracket to be pivoted slightly about it, and said second screw member acting as a locking member for locking a particular angular position of said support bracket relative to said external housing, whereby the assembled linear encoder may be tested, the angular position of said support bracket adjusted to attain the proper scale factor, and then said first and second screws may be tightened to secure the adjusted angular position of said support bracket.
Claim 6
Dependent Claim
100 words
Apparatus as set forth in claim 1 wherein: a. said torque means includes a second cylinder mounted directly upon said central shaft for rotation therewith; b. a pick-up cylinder mounted on said support body to rotate about an axis substantially parallel to the axis of said shaft and being adjacent to said second cylinder; and c. a prestressed spring element extending between said second cylinder and said pick-up cylinder and being oppositely wound on said pickup and second cylinders in a manner to exert a constant torque upon said central shaft and thereby maintain said measuring tape under constant tension.
Claim 7
Dependent Claim
27 words
Apparatus as set forth in claim 1 wherein said central shaft, said measuring cylinder and said second cylinder are formed of one unitary molded piece of material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |