US3757128A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiphase tachometer
Assignee: International Business Machines Corp
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Filing: 1972-03-20
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Granted: 1973-09-04
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Expires: 1992-03-20
Abstract
Abstract A multiphase tachometer is substantially insensitive to minute relative position changes between a sensing element and the moving tachometer member. Interdigited techniques, including integrated circuit sensing elements, minimize the distance between sensing elements.
Inventors
- 👤 J Vermeuln
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:08
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/486
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
183 words
A plural phase tachometer, including in combination: a light source, sensing means, a single light path extending between said source and sensing means; a circular tachometer element rotatable about a given axis having light path breaking and making portions of given shape and circumferential pitch, said portions being circumferentially equally spaced apart coaxial to said given axis and interposed between said source and sensing means to alternately interrupt and complete said single light path as said element rotates about said given axis; and said sensing means including mask means limiting light to a given area on said sensing means, a first light-responsive finger having a shape like said portions and extending along said area substantially parallel to and axially spaced from said portions, and a second light-responsive finger extending along said area and having a shape like said portions and spaced from said first light-responsive finger in a circumferential direction a given proportion of said pitch less than unity and being radially coextensive with said first light-responsive finger such that both said light-responsive fingers substantially subtend the same area of said tachometer element.
Claim 2
Dependent Claim
183 words
A plural phase tachometer, including in combination: a light source, sensing means, a single light path extending between said source and sensing means; a circular tachometer element rotatable about a given axis having light path breaking and making portions of given shape and circumferential pitch, said portions being circumferentially equally spaced apart coaxial to said given axis and interposed between said source and sensing means to alternately interrupt and complete said single light path as said element rotates about said given axis; and said sensing means including mask means limiting light to a given area on said sensing means, a first light-responsive finger having a shape like said portions and extending along said area substantially parallel to and axially spaced from said portions, and a second light-responsive finger extending along said area and having a shape like said portions and spaced from said first light-responsive finger in a circumferential direction a given proportion of said pitch less than unity and being radially coextensive with said first light-responsive finger such that both said light-responsive fingers substantially subtend the same area of said tachometer element.
Claim 3
Dependent Claim
66 words
The apparatus set forth in claim 1, the improvement further including: said mask means extending circumferentially a given length approximately equal to an integral number of said pitches; a given number of said first light-responsive fingers and a given number of said second light-responsive fingers disposed in said given area; and all of said first light-responsive fingers and said second light-responsive fingers being connected together, respectively.
Claim 4
Dependent Claim
62 words
The subject matter set forth in claim 2 wherein said first light-responsive fingers extend radially inwardly with respect to said element and said second light-responsive fingers extend radially outward thereof; and conductive means connected respectively to said first and second light-responsive fingers respectively on the radial outward and radial inward portion of said sensing element means such that said elements are interdigitated.
Claim 5
Dependent Claim
49 words
The subject matter set forth in claim 3 further including a semiconductive chip, said chip including said first and second light-responsive fingers and said conductive means; and wherein said given proportion is one-fourth to yield a 90* phase difference between signals induced in said first and second light-responsive fingers.
Claim 6
Dependent Claim
52 words
The subject matter set forth in claim 3 wherein said circumferential extent of said first and second light-responsive fingers is shorter than said pitch and the light path making portions being shorter than said pitch such that the total light area impinging upon a given light-responsive finger is smaller than dark areas.
Claim 7
Dependent Claim
81 words
The plural phase tachometer set forth in claim 1 further including a third light-responsive finger extending along said area radially coextensive with said first and second light-responsive fingers and having a shape like said portions and disposed parallel to said first and second light-responsive fingers; all said light-responsive fingers circumferentially lying within a distance equal to said pitch; and means connected to each said light-responsive fingers for receiving electrical signals from each said light-responsive fingers for generating three-phase output tachometer signals.
Claim 8
Dependent Claim
33 words
The plural phase tachometer set forth in claim 1 wherein each said light-responsive fingers and said portions being tangentially oriented about a circle coaxial with an axis of rotation of said tachometer element.
Claim 9
Dependent Claim
120 words
A tachometer signal generator adapted to operate with a tachometer element having alternating light and dark means of given geometric configuration extending in given direction and having a given pitch transverse to said given direction, including in combination: a support; first sensing means on said support of approximately said given geometric configuration and extending along said given direction; second sensing means on said support of approximately said given geometric configuration and coextensive with said first sensing means along said given direction and disposed parallel to said first sensing means and spaced therefrom a given proportion of said pitch less than unity along said transverse direction; and output means on said support connected to said means for supplying output tachometer signals.
Claim 10
Dependent Claim
120 words
A tachometer signal generator adapted to operate with a tachometer element having alternating light and dark means of given geometric configuration extending in given direction and having a given pitch transverse to said given direction, including in combination: a support; first sensing means on said support of approximately said given geometric configuration and extending along said given direction; second sensing means on said support of approximately said given geometric configuration and coextensive with said first sensing means along said given direction and disposed parallel to said first sensing means and spaced therefrom a given proportion of said pitch less than unity along said transverse direction; and output means on said support connected to said means for supplying output tachometer signals.
Claim 11
Dependent Claim
181 words
The signal generator set forth in claim 8, a mask area on said generator, said output means includes a pair of conductive means extending on opposite extremities of said sensing means in said given direction and said conductive means being outside said mask area; a plurality of said first sensing means extending along said first direction from a first of said conductive means toward a second of said conductive means and being separated precisely in accordance with said given pitch; and a like plurality of said second sensing means extending toward said one conductive means from said other conductive means and separated from each other precisely by said given pitch, and all of said second sensing means having said proportional relationship to said first sensing means along said transverse direction for yielding a predetermined phase difference between signals supplied through said one and other conductive means and the arrangement being such that said sensing means is interdigitated and establishes said given proportion through said interdigitation for subtending the same light-impinging area for limiting phase shift between said sensing means generated signals.
Claim 12
Dependent Claim
49 words
The generator set forth in claim 9, a common axis, said sensing means extending along various radii of said common axis, and all of said sensing means having approximately the same cross-sectional light-responsive areas smaller than the areas within said mask limiting light area which include nonresponsive light portions.
Claim 13
Dependent Claim
35 words
The generator set forth in claim 9, a common axis, said sensing means being circumferentially spaced apart about said common axis and being radially coextensive and all said sensing means being coaxial to said axis.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |