Radiation-based contactless position reference system and method for elevators
US6437315B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | May 31, 2000 |
| Grant date | Aug 20, 2002 |
| Priority date | — |
| Expiry date | May 31, 2020 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B1/3492
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A position reference system for an elevator car includes a laser that emits a beam that is reflected from a mirror. Either the laser or the mirror is in a non-moving position, while the other is fixed to the elevator car and moves with it. The laser beam is modulated at two frequencies, one of which provides a coarse position of the elevator car while the other provides a fine position of the elevator car. Position calibration occurs when the elevator car is stationary. When the elevator car begins to move, the coarse position is tracked while the fine position is determined from the higher of the two modulation frequencies. The absolute position of the moving elevator car is thus always known to a degree of accuracy depending on the higher modulation frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.