| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an "amplifier equipped with a speaker connection detection function" which, even when a number of speakers varying in type are connected to the amplifier, can detect speaker connections easily and accurately with a single detection element by only sending small currents almost at the same time, without the need for adding resistors in a circuit. <P>SOLUTION: A test signal is input to a plurality of per-speaker audio signal input lines. Among output lines from per-speaker output blocks, plus side wiring or minus side wiring is laid collectively together while the other wiring is shifted, when laid, to a position at which it does not exert current induced magnetic effects. A collectively disposed wiring section is provided with a magnetic sensor at a position suitable for detecting magnetism due to a current in each wiring, to detect magnetism due to a current in each wiring in which a test signal runs. In a connection determination unit, a current value derived by converting a detected magnetic signal into a current is compared with preset upper-limit and lower-limit thresholds, and, if the compared value does not fall within that range, a poor connection or short-circuit is assumed. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
