Initial command to switch transistors disconnecting keys from microphone line
US9479882B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 2013 |
| Grant date | Oct 25, 2016 |
| Priority date | — |
| Expiry date | Dec 21, 2034 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R29/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An audio accessory key detection system (40) includes a host circuit (2-3) coupled to communicate via a microphone line (7) with an accessory circuit (3-3) in either a MSFT mode or a digital communication mode. Depletion mode transistors (44-1,2,3) in the accessory circuit are coupled between keys (15-1,2,3) of the accessory circuit, respectively. The depletion mode transistors are allowed to remain conductive for MSFT mode operation. For digital communications mode operation, the host circuit sends a command via the microphone line to a key detector and controller circuit (29A) in the accessory circuit. In response, a voltage is generated to turn the depletion mode transistors off so as to allow digital communications mode operation between the accessory circuit and the host circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.