| 摘要 |
PROBLEM TO BE SOLVED: To provide a detection circuit for microphone plug and line plug that can use a microphone jack and a line jack in common, a common use circuit for the jack, an adaptor using the jack in common, and a notebook PC provided with the common use jack. SOLUTION: While a plug of an external device to be connected is plugged into a jack and connected, a difference of impedance between a ring pin and a tip pin of the jack is obtained, whether the jack to which the external device is connected is a microphone or a line jack is detected on the basis of the difference of impedance to be obtained. In the case of the microphone jack, it is controlled so that a DC bias is applied to the ring pin or the tip pin of the jack, and in the case of the line jack, no DC bias is given to the ring pin and the tip pin of the jack, or in the case of a device using the line jack, the device is connected to the common use jack via an adaptor with a prescribed DC cut function. |
