Annunciator circuit for elevator systems
US4684927A · kind A · utility
3Cited by
3References
18Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 20, 1986 |
| Grant date | Aug 4, 1987 |
| Priority date | — |
| Expiry date | May 20, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B3/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A highly reliable annunciator circuit which is immune from spurious signals generated in an elevator environment is provided. The circuit employs an input condition verification network which performs in conjunction with low true logic two-bit inputs by carrying out switching only when those inputs fall below a preset control value, highly enhanced performance is achieved. Volume control over the piezoelectric output developing a chime or gong sound is achieved through a variable impedance control which is adjustable on site.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.