The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 2009
Filed:
Aug. 17, 2007
Applicant:
Chengjun Julian Chen, White Plains, NY (US);
Inventor:
Chengjun Julian Chen, White Plains, NY (US);
Assignee:
The Trustees of Columbia University in the City of New York, New York, NY (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
G04B 49/00 (2006.01); G01C 17/34 (2006.01);
U.S. Cl.
CPC ...
Abstract
Sundials and solar compasses including are disclosed. Some embodiments include an omni-directional lens, which can focus a sun beam into a sharp spot with a long depth of field. By projecting the spot onto a cylindrical panel, both the day of the year and the time of the day can be read off simultaneously with very high accuracy. Because of the simultaneous displaying of time and date, no equation-of-time correction is required. If the time is known, the true north can be determined with high accuracy, and the device becomes a reliable and easy-to-use solar compass.