Mobile acoustic reproducing apparatus

• US 5,068,897 A
• Filed: 04/26/1990
• Issued: 11/26/1991
• Est. Priority Date: 04/26/1989
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Ito, Tatsuo, Takashima, Atsuyuki, Yamato, Toshitaka, Motojima, Akira
• Primary Examiner(s): Isen, Forester W.
• Application Number:
  US07/514,833
• Time in Patent Office: 579 Days
• Field of Search: 381/86, 381/24, 381/97
• US Class Current: 381/302
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04S 5/005 of the pseudo five- or more-channel type, e.g. virtual surround

Abstract

A center loudspeaker is disposed near the middle between the left channel loudspeaker arranged at the front left side of the compartment and the right channel loudspeaker at the front right side, and this center loudspeaker transforms into a sound by the level-controlled signal of the sum of the acoustic signals of the right and left channels, and phase- and level-controlled signals of the acoustic signals of the right and left channels. As a result, the sound field is localized in the front of the listener, and right and left symmetrical wide-spread sound fields may be composed. Additionally, tweeters are disposed outside the right and left channel loudspeakers, and the mounting angles of the tweeters are adjusted so that the sounds released from the tweeters may be at an equal sound pressure level between the listener at the driver'"'"'s seat and the listener at the front side seat. As a result, the drift of the sound field in the medium and high sound ranges may be eliminated in a simple structure, and right and left symmetrical wide-spread sound field are composed. Furthermore, corresponding to the opening or closing state of the window glass or seated position, by controlling the phase and level of the sounds released from the loudspeakers and the tweeters, sound fields always symmetrical to the listening position and spread widely may be composed.

Claims

1. A mobile acoustic reproducing apparatus comprising:

right and left loudspeakers disposed at positions at mutually different directional angles at the front right and front left positions of the listener,

a center loudspeaker positioned near the middle between the right and left loudspeakers, and disposed at a position of a directional angle larger than one of the right and left loudspeakers and smaller than the other one of the right and left loudspeakers,

an acoustic signal source for delivering an acoustic signal of a left channel to the left loudspeaker and an acoustic signal of a right channel to the right loudspeaker,

means for correcting the right channel and left channel acoustic signals by phase and level, and providing corresponding right and left correction signals,

means for adding the acoustic signals of the right and left channels, correcting the level thereof, and providing corresponding center correction signals,

means for adding the right and left correction signals and the center correction signal, and correcting the phase to feed to the center loudspeaker,

right and left tweeters disposed at the front right and front left sides of the listener and at a position of a larger directional angle than the directional angles of the right and left loudspeakers,

right and left high pass filters for filtering signals over a predetermined frequency of the acoustic signals of the right and left channels, and feeding corresponding filtered signals to the right and left tweeters, and

right and left level adjusting means for adjusting the level ratio of acoustic signal levels supplied to the right and left tweeters and acoustic signal levels supplied to the right, left and center loudspeakers.

2. A mobile acoustic reproducing apparatus comprising:

first loudspeakers disposed at the front right, left and near middle positions of a compartment so as to compose a sound field at a left seat by the left first loudspeaker and the middle first loudspeaker and a sound field at a right seat by the right first loudspeaker and the near middle first loudspeaker, by processing the phase of the left channel acoustic signal and feeding a corresponding signal to the left side first loudspeaker, processing the phase of the right channel acoustic signal and feeding a corresponding signal to the right side first loudspeaker, and processing the level and phase of the right and left channel acoustic signals and feeding a corresponding signal to the near middle first loudspeaker, and

second loudspeakers for reproducing medium and high sound ranges, disposed at the right and left sides of the compartment, by processing the phase of the left channel acoustic signal and feeding a corresponding signal to the left side second loudspeaker, and processing the phase of the right channel acoustic signal and feeding a corresponding signal to the right side second loudspeaker,

wherein the directivity of the left side second loudspeaker is mountably adjusted so that the acoustic level from the left side second loudspeaker is substantially equal at the left side seat and right side seat, and the directivity of the right side second loudspeaker is mountably adjusted so that the acoustic level from the right side second loudspeaker is substantially equal at the right side seat and left side seat.

3. A mobile acoustic reproducing apparatus comprising:

right and left loudspeakers disposed at the front right and left positions of a listener,

a center loudspeaker disposed near the middle of the right and left loudspeakers, an acoustic signal source for delivering the acoustic signal of the left channel to the left loudspeaker and the acoustic signal of the right channel to the right loudspeaker, and

first addition means for adding up the acoustic signals of the right and left channels and delivering to the center loudspeaker, wherein

part of the sound released from the right loudspeaker is reflected by the right wall to reach the listener at the right seat, while part of the sound released from the left loudspeaker is reflected by the left wall to reach the listener at the left seat, which further comprises;

reflected wave correction means composed of;

equalizer means having frequency characteristics of reflected waves by the right and left walls,

delay means for compensating the propagation route difference of the direct sound from the center loudspeaker and the reflected waves,

means for inverting the signal polarity, and

means for adjusting the level of the attenuation corresponding to the reflectivity of the wall, thereby receiving the output from the first addition means, and second addition means for adding the output from the reflected wave correction means to the output from the first addition means, correcting the reflected wave, and delivering to the center loudspeaker.

4. A mobile acoustic reproducing apparatus comprising:

signal processing means for arithmetically processing according to predetermined operation constants right and left channel stereo acoustic signals output from an acoustic signal source, and for composing and outputting corresponding plural acoustic signals to respective plural loudspeakers;

seat position detecting means associated with a seat upon which a listener sits, the seat being movable fore and back and having an adjustable reclining angle, said seat position detecting means for detecting a seat position and reclining angle of the seat; and

,

constant setting means for setting the operational constants to obtain a right and left symmetrical sound field about the head of the listener sitting on the seat based on the seat position and reclining angle detected by the seat position detecting means, and for providing the operational constants to the signal processing means.