Earphone device
US5276740A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1993 |
| Grant date | Jan 4, 1994 |
| Priority date | — |
| Expiry date | Feb 16, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R1/1016
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
An earphone device includes an acoustic tube having an inner diameter substantially identical to that of the external auditory canal has an ear mounting portion at one end and an acoustic non-reflecting portion at the outer end. An earphone unit and an internal microphone unit are mounted on the periphery of the acoustic tube adjacent each other and communicate with the interior of the acoustic tube with their respective vibration plates facing inwardly of the tube. The phase of the signal representing the external noise in the acoustic tube picked up by the internal microphone unit is reversed and combined with the audio signal fed to the earphone unit. The earphone device also includes an external microphone unit on the outside of the acoustic tube and a variable ratio mixing circuit for mixing the input audio program signal, the reversed phase signal obtained from the internal microphone unit, and the signal from the external microphone unit, so that external sounds can be heard without removing the earphone device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.