Generation of an elevator door close warning
US5821478A · kind A · utility
4Cited by
4References
19Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1996 |
| Grant date | Oct 13, 1998 |
| Priority date | — |
| Expiry date | Nov 25, 2016 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66B13/143
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
An acoustic signal in an elevator door system is provided if a door close signal is present and a door has not closed within a determined time. A switching frequency of a pulse width modulation signal is reduced such that a motor is caused to provide the acoustic signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.