| 摘要 |
PURPOSE:To prevent the occurrences of a rattle sound and distortion by providing a means impressing a DC signal to correct the displacement of the diaphragm of a speaker unit in addition to a voice signal to be impressed to the speaker unit. CONSTITUTION:When the voice signal is impressed to a terminal 24, a first and a second amplifiers 26, 28 operate in inverse phases each other, and act as a well-known BTL amplifier and drive the speaker unit. Additionally, when a DC correction signal is impressed to an input terminal 31, the signal undergoes a buffer amplifier 30 similar to the case of the voice signal, the signal is inputted to the first and the second amplifiers 26, 28 in inverse-phase relation, hence the voice coil of the speaker unit 10 is driven to shift in one direction. Therefore, the inclination of the diaphragm to shift toward the outside of the vehicle on account of a pressure down in a duct as the vehicle runs, can be corrected in the effect of the correction signal impressed to the terminal 31.
|
