Life safety device with folded resonant cavity for low frequency alarm tones
US9179220B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 9, 2013 |
| Grant date | Nov 3, 2015 |
| Priority date | — |
| Expiry date | Jul 9, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R17/10
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Low frequency alarm tones emitted by life safety devices are more like to notify sleeping children and the elderly. Disclosed herein is a life safety device equipped with a novel, compact, quarter-wave, folded resonant cavity which significantly increases the low frequency (400-700 Hz square wave) acoustic efficiency of an audio output transducer when the folded resonant cavity is acoustically coupled to the transducer forming an audio output apparatus. The folded resonant cavity is comprised of undulating, annular, acoustic passages to significantly reduce the length of the resonant cavity, thereby permitting the audio output apparatus to fit within the housing of conventional size life safety devices such as, but not limited to, residential and commercial smoke alarms and carbon monoxide alarms. Battery powered embodiments of the audio output apparatus comprising a folded resonant cavity passed audibility tests for low frequency alarm tones in smoke alarms specified by UL217.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.