US3815249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shadowless sun dial
Assignee: VENCRAFT CORP
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Filing: 1972-06-08
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Granted: 1974-06-11
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Expires: 1992-06-08
Abstract
Abstract A sundial is formed with a reflecting surface curving in an arc around an axis so that the image of the sun reflected from the surface can be viewed from points along the axis. The surface is mounted with its axis parallel to the axis of the rotation of the earth, and a time scale, also visible from the axis, indicates the time position of the reflected image of the sun.
Inventors
- 👤 R Gundlach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:20
CPC Classifications
G; G04; G04B; G04B49/00
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
102 words
A shadowless sundial comprising: a. means for defining an axis and, connected in a fixed relationship thereto, a body having a reflecting surface forming at least a segment of a substantially annular surface generally transverse to said axis and whose center of curvature lies on said axis; b. mounting means connected to said body for maintaining said axis approximately parallel to the axis of rotation of the earth; and c. time scale means carried by said body for indicating the time position of the reflected image of the sun formed on said reflecting surface as viewed from a point on said axis.
Claim 2
Dependent Claim
102 words
A shadowless sundial comprising: a. means for defining an axis and, connected in a fixed relationship thereto, a body having a reflecting surface forming at least a segment of a substantially annular surface generally transverse to said axis and whose center of curvature lies on said axis; b. mounting means connected to said body for maintaining said axis approximately parallel to the axis of rotation of the earth; and c. time scale means carried by said body for indicating the time position of the reflected image of the sun formed on said reflecting surface as viewed from a point on said axis.
Claim 3
Dependent Claim
22 words
The sundial of claim 1 wherein said means defining an axis comprises sight means arranged for indicating on-axis viewing of said sundial.
Claim 4
Dependent Claim
24 words
The sundial of claim 2 wherein said sight means comprises a mirror perpendicular to said axis for reflecting an image of the viewer''s eye.
Claim 5
Dependent Claim
13 words
The sundial of claim 2 wherein said sight means includes an axial hole.
Claim 6
Dependent Claim
20 words
The sundial of claim 2 wherein said sight means comprises a pair of spaced sight pieces arranged on said axis.
Claim 7
Dependent Claim
23 words
The sundial of claim 1 including apparatus arranged on said axis for making said reflected image of said sun visible to a viewer.
Claim 8
Dependent Claim
21 words
The sundial of claim 1 wherein said reflecting surface is formed as rings of different radii generally perpendicular to said axis.
Claim 9
Dependent Claim
14 words
The sundial of claim 7 wherein said rings are in a generally conical form.
Claim 10
Dependent Claim
21 words
The sundial of claim 7 wherein said rings are arranged next to each other in the general form of a disk.
Claim 11
Dependent Claim
14 words
The sundial of claim 9 wherein said disk formed by said rings is convex.
Claim 12
Dependent Claim
14 words
The sundial of claim 7 wherein said rings are formed as a Fresnel lens.
Claim 13
Dependent Claim
29 words
The sundial of claim 1 wherein said reflecting surface comprises a length of narrow reflective material wound around said axis at continually increasing radii forming a closely wound spiral.
Claim 14
Dependent Claim
16 words
The sundial of claim 12 wherein said reflective material is wound in a generally conical form.
Claim 15
Dependent Claim
16 words
The sundial of claim 12 where said reflective material is wound in a convex spherical form.
Claim 16
Dependent Claim
25 words
The sundial of claim 1 wherein said scale means is circular and includEs means mounting a circular time scale for rotational movement about said axis.
Claim 17
Dependent Claim
36 words
The sundial of claim 15 including fixed and rotatable sets of adjustment markers on said time scale and said body, respectively arranged to be selectively matched in coincidence to compensate for the earth''s equation of time.
Claim 18
Dependent Claim
19 words
The sundial of claim 16 wherein one of said sets of said markers represents the months of the year.
Claim 19
Dependent Claim
19 words
The sundial of claim 16 wherein one of said sets of said markers is spaced uniformly at 15* intervals.
Claim 20
Dependent Claim
21 words
The sundial of claim 18 wherein the other one of said sets of said markers represents the months of the year.
Claim 21
Dependent Claim
19 words
The sundial of claim 1 wherein said reflecting surface is a specularly reflecting surface of revolution around said axis.
Claim 22
Dependent Claim
12 words
The sundial of claim 20 wherein said reflecting surface is generally conical.
Claim 23
Dependent Claim
12 words
The sundial of claim 20 wherein said reflecting surface is generally spherical.
Claim 24
Dependent Claim
12 words
The sundial of claim 20 wherein said reflecting surface is generally convex.
Claim 25
Dependent Claim
16 words
The sundial of claim 20 wherein said reflecting surface is formed as rings of different radii.
Claim 26
Dependent Claim
21 words
The sundial of claim 20 wherein said scale means is circular and has hourly divisions spaced at equal intervals of 15*.
Claim 27
Dependent Claim
25 words
The sundial of claim 25 wherein said scale means is circular and includes means mounting a circular time scale for rotational movement about said axis.
Claim 28
Dependent Claim
47 words
The sundial of claim 26 including fixed and rotatable sets of adjustment markers on said time scale and said body, respectively arranged to be selectively matched in coincidence to compensate for the earth''s equation of time, and one of said sets represents the months of the year.
Claim 29
Dependent Claim
35 words
The sundial of claim 27 wherein one of said sets of said markers is spaced uniformly at 15* intervals and the other one of said sets of said markers represents the months of the year.
References Cited (Backward Citations)
US2207195A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-10 | 1977-12-10 | 1978-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-10 | 1981-12-10 | 1982-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-10 | 1985-12-10 | 1986-06-11 | $7700.00 | Window Closed / Lapsed |