Patent US3799678A successfully refreshed from Google Patents.
US3799678A
Expired / Lapsed
US
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Position measuring device
Assignee: Ferranti International PLC
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Filing: 1972-05-31
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Granted: 1974-03-26
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Expires: 1992-05-31
Abstract
Abstract A position indicating device includes a pantograph linkage employed to reduce the scale of the displacement of a first point on the pantograph to a corresponding displacement of a second point on the pantograph. The displacement of the second point is measured with respect to two co-ordinate axes by accurate means such as interference fringes produced by relative movement between optical diffraction gratings to give an accurate indication of the large scale movement of the first point. Means is provided to maintain the relative orientation of the diffraction gratings to produce interference fringes for all movements of the second point.
Inventors
- 👤 A Kerr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:13
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/38
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
93 words
A position measuring device including a pantograph linkage comprising four rigid members freely jointed in the form of a parallelogram wherein displacement of a first point on the linkage is translated into a corresponding displacement of a second point on the linkage on a reduced scale, and apparatus for measuring the magnitude of a displacement of the second point including a part pivotally connected to the second point for displacement thereby and means for constraining movement of the part so that the part is maintained in a predetermined orientation to two co-ordinate axes.
Claim 2
Dependent Claim
93 words
A position measuring device including a pantograph linkage comprising four rigid members freely jointed in the form of a parallelogram wherein displacement of a first point on the linkage is translated into a corresponding displacement of a second point on the linkage on a reduced scale, and apparatus for measuring the magnitude of a displacement of the second point including a part pivotally connected to the second point for displacement thereby and means for constraining movement of the part so that the part is maintained in a predetermined orientation to two co-ordinate axes.
Claim 3
Dependent Claim
19 words
A position measuring device as claimed in claim 1 in which the co-ordinate axes are perpendicular to each other.
Claim 4
Dependent Claim
64 words
A position measuring device as claimed in claim 1 in which the apparatus for measuring the magnitude of a displacement of the second point also includes first optical diffraction gratings fixed individually in relation to each of said co-ordinate axes and second optical diffraction gratings fixed to said part of the apparatus and movable relative to and in operable relationship with said first gratings.
Claim 5
Dependent Claim
97 words
A position measuring device as claimed in claim 1 in which the means for constraining movement of said part of the apparatus comprises a linkage of members arranged in the form of first and second freely jointed parallelograms, one side of the first parallelogram being fixed in relation to the co-ordinate axes, one side of the second parallelogram being rigidly attached to said part and the side opposite to said one side of the first parallelogram and the side opposite to said one side of the second parallelogram being constrained at a predetermined angle to each other.
Claim 6
Dependent Claim
17 words
A position measuring device as claimed in claim 4 in which the predetermined angle is a right-angle.
Claim 7
Dependent Claim
33 words
A position measuring device as claimed in claim 4 in which one of the members interconnecting said opposite sides of each of said first and second parallelograms is common with the pantograph linkage.
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) | 1977-03-25 | 1977-09-24 | 1978-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-25 | 1981-09-24 | 1982-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-25 | 1985-09-24 | 1986-03-26 | $7700.00 | Window Closed / Lapsed |