US3553470A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for generating an approximation to a sine wave including a reading head with two spaced areas for scanning an optical grating
Assignee: George Richards and Co Ltd
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Filing: 1968-03-15
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Granted: 1971-01-05
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Expires: 1988-03-15
Abstract
Abstract The invention is concerned with a reading head for moving in relation to an optical grating for giving a position signal. The position signal may be made very nearly the true sine wave by appropriate choice of the spacing between apertures in the head in relation to the pitch of the grating and/or by appropriate shape of the apertures.
Inventors
- 👤 Michael J Dench
- 👤 Rowland Clive Robbins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:07
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/366
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
82 words
Apparatus for generating an approximation to a sine wave including an optical grating, a lamp for illuminating the grating, a reading head which is movable in relation to the grating and contains means defining two spaced local areas of the grating for examination, and a photocell means for examining the areas, the local areas being spaced apart by an odd number of nth fractional parts of half the pitch of the grating where n is one of the integers 3,5,7 and 9.
Claim 2
Dependent Claim
82 words
Apparatus for generating an approximation to a sine wave including an optical grating, a lamp for illuminating the grating, a reading head which is movable in relation to the grating and contains means defining two spaced local areas of the grating for examination, and a photocell means for examining the areas, the local areas being spaced apart by an odd number of nth fractional parts of half the pitch of the grating where n is one of the integers 3,5,7 and 9.
Claim 3
Dependent Claim
25 words
Apparatus as claimed in claim 1 in which the grating consists of alternate lines and spaces or dark and light regions of approximately rectangular shape.
Claim 4
Dependent Claim
19 words
Apparatus as claimed in claim 1 in which the means defining the local areas comprises a pair of apertures.
Claim 5
Dependent Claim
15 words
Apparatus as claimed in claim 2 in which the local areas are of rectangular shape.
Claim 6
Dependent Claim
24 words
Apparatus as claimed in claim 4 in which the local areas have a width equal to one third of the pitch of the grating.
Claim 7
Dependent Claim
10 words
Apparatus as claimed in claim 5 in which n 5.
Claim 8
Dependent Claim
10 words
Apparatus as claimed in claim 5 in which n 7.
Claim 9
Dependent Claim
50 words
Apparatus as claimed in claim 1 in which the grating spaces or the local areas are each in the shape of a trapezium while the local areas or the grating spaces are each in the shape of a rectangle whose length is perpendicular to the parallel sides of the trapezium.
Claim 10
Dependent Claim
33 words
Apparatus as claimed in claim 8 in which the trapezium is symmetrical and its parallel sides have lengths in the ratio 1:3 the larger side being equal to the width of the rectangle.
Claim 11
Dependent Claim
37 words
Apparatus as claimed in claim 8 in which the spaces or local areas are in the shape of a double trapezium comprising a trapezium as defined together with its mirror image about one of the parallel sides.
Claim 12
Dependent Claim
79 words
Apparatus as claimed in claim 1 including m groups of local areas of which the local areas in a group are spaced apart to eliminate the nth harmonic, the separate groups being spaced apart by a number of qth fractional parts of 1/nth the pitch of the grating, and including means arranged to combine signals derived from examination of the local areas to provide a combined signal from which the qth harmonic of the fundamental frequency has been eliminated.
Claim 13
Dependent Claim
37 words
Apparatus as claimed in claim 9 in which the spaces or local areas are in the shape of a double trapezium comprising a trapezium as defined together with its mirror image about one of the parallel sides.
References Cited (Backward Citations)
GB846771A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |