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:
Apr. 26, 1994
Filed:
May. 13, 1991
Otis Elevator Company, Farmington, CT (US);
Abstract
A microphone 13 is provided upon the ceiling 4 of an elevator hoistway 3 and a loudspeaker 8 upon the top of an elevator car 1. A 9-16 kHz up-sweep is provided to the loudspeaker 8 and a sound signal is transmitted from the loudspeaker 8 to the microphone 13. The travel time of the sound signal is obtained by cross-correlating 53 the sound signal received by the microphone 13 with a reference signal. The reference signal is a received signal in a relatively noiseless environment. By multiplying the travel time of the signal by its velocity, the distance between microphone and loudspeaker is calculated 59. The hoistway temperature is measured 26 and used 57 in the absolute position calculation 59.