US3731107A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical shaft encoder
Assignee: RTX Corp
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Filing: 1971-12-15
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Granted: 1973-05-01
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Expires: 1991-12-15
Abstract
Abstract Light is transmitted through the edge of a transparent cylinder, a portion of the light inside the cylinder being incident to at least one face thereof at greater than the critical angle between the cylinder and air. Light escapes from the faces at a plurality of selected locations thereon in a plurality of unique output patterns, associated with angular positions of the cylinder. Stationary optical detectors, opposite the faces, detect the escaping light when the cylinder is rotated to a position that places a selected location opposite an optical detector. The optical detectors provide signals representative of a unique pattern and hence the angular position of the cylinder. In one embodiment a material having an index of refraction intermediate to that of the cylinder and air is disposed at the selected locations, providing a critical angle greater than the critical angle between the cylinder and the environment, thereby causing light to escape through the faces only at the selected locations. In another embodiment, notches in the faces of the cylinder are disposed at the selected locations, the notches being at an angle so that light is incident thereto at an angle less than the critical angle, thereby causing light to escape through the faces only at the selected locations.
Inventors
- 👤 R Goodwin
- 👤 J Alimena
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:05
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/347; G01D5/34707; G01D5/34715; G01D5/34723
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
221 words
A shaft angle encoder comprising: a cylinder having an index of refraction greater than that of the environment, said cylinder being rotatable about its axis within the environment; a light source disposed to provide light that it is transmitted through the curved edge of said cylinder, said light being incident to at least one planar face of said cylinder at an angle greater than a first critical angle that is associated with the indexes of refraction of said cylinder and the environment thereby causing multiple reflections of said incident light between the planar faces of said cylinder, said cylinder including transparent encoding means disposed contiguous with at least one planar face of said cylinder for permitting light to escape therethrough from said cylinder in an output pattern of light associated with the angular position thereof, said encoding means comprising material having an index of refraction intermediate to the indexes of refraction of said cylinder and the environment, said light source providing said incident light to at least one planar face of said cylinder at an angle intermediate to said first critical angle and a second critical angle associated with the indexes of refraction of said cylinder and said material; and means responsive to said output pattern for providing a signal representative of the angular position in response to said escaping light.
Claim 2
Dependent Claim
221 words
A shaft angle encoder comprising: a cylinder having an index of refraction greater than that of the environment, said cylinder being rotatable about its axis within the environment; a light source disposed to provide light that it is transmitted through the curved edge of said cylinder, said light being incident to at least one planar face of said cylinder at an angle greater than a first critical angle that is associated with the indexes of refraction of said cylinder and the environment thereby causing multiple reflections of said incident light between the planar faces of said cylinder, said cylinder including transparent encoding means disposed contiguous with at least one planar face of said cylinder for permitting light to escape therethrough from said cylinder in an output pattern of light associated with the angular position thereof, said encoding means comprising material having an index of refraction intermediate to the indexes of refraction of said cylinder and the environment, said light source providing said incident light to at least one planar face of said cylinder at an angle intermediate to said first critical angle and a second critical angle associated with the indexes of refraction of said cylinder and said material; and means responsive to said output pattern for providing a signal representative of the angular position in response to said escaping light.
Claim 3
Dependent Claim
196 words
A shaft angle encoder comprising: a cylinder having an index of refraction greater than that of the environment, said cylinder being rotatable about its axis within the environment; a light source disposed to provide light that is transmitted through the curved edge of said cylinder, said light being incident to at least one planar face of said cylinder at an angle greater than a first critical angle that is associated with the indexes of refraction of said cylinder and the environment thereby causing multiple reflections of said incident light between the planar faces of said cylinder, said cylinder including transparent encoding means disposed contiguous with at least one planar face of said cylinder for permitting light to escape therethrough from said cylinder in an output pattern of light associated with the angular position thereof, said encoding means comprises at least one notch within at least one planar face of said cylinder, said notch being at an angle so that said incident light is incident to the notch at less than said first critical angle; and means responsive to said output pattern for providing a signal representative of the angular position in response to said escaping light.
Claim 4
Dependent Claim
196 words
A shaft angle encoder comprising: a cylinder having an index of refraction greater than that of the environment, said cylinder being rotatable about its axis within the environment; a light source disposed to provide light that is transmitted through the curved edge of said cylinder, said light being incident to at least one planar face of said cylinder at an angle greater than a first critical angle that is associated with the indexes of refraction of said cylinder and the environment thereby causing multiple reflections of said incident light between the planar faces of said cylinder, said cylinder including transparent encoding means disposed contiguous with at least one planar face of said cylinder for permitting light to escape therethrough from said cylinder in an output pattern of light associated with the angular position thereof, said encoding means comprises at least one notch within at least one planar face of said cylinder, said notch being at an angle so that said incident light is incident to the notch at less than said first critical angle; and means responsive to said output pattern for providing a signal representative of the angular position in response to said escaping light.
Claim 5
Dependent Claim
31 words
Apparatus according to claim 1 wherein said cylinder is comprised of a plastic and said material is an optical coating material selected from the group consisting of cryolite and magnesium fluoride.
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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) | 1976-04-30 | 1976-10-30 | 1977-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-30 | 1980-10-30 | 1981-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-30 | 1984-10-30 | 1985-05-01 | $7700.00 | Window Closed / Lapsed |