Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Having acoustic wave modifying structure
Reexamination Certificate
1998-02-26
2002-01-29
Mei, Xu (Department: 2743)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Having acoustic wave modifying structure
C381S160000, C381S306000, C181S185000, C181S191000
Reexamination Certificate
active
06343132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a loudspeaker combined with a picture image reproducer is so constructed as to reproduce a center channel signal in a multichannel sound signal for a movie or the like as a principal object, and more particularly, to realization of reproduction in which a sound image and a picture image coincide with each other utilizing characteristics in acoustic psychology.
2. Related Art Statement
In recent years, impressive and powerful movies or the like have been increasingly enjoyed, even in homes upon being reproduced by combining a large screen television (TV) and a sound reproducer for reproducing a multichannel sound signal, for example, a Dolby prologic.
As shown in
FIG. 16
, a conventional multichannel sound reproducer combined with such a picture image reproducer comprises a loudspeaker
2
L for reproducing a left channel signal and a loudspeaker
2
R for reproducing a right channel signal which are located on the left and right sides of a TV
5
placed ahead of a viewer
6
, a loudspeaker
11
located on the TV
5
for reproducing a center channel signal, and two loudspeakers
4
R and
4
L located at the sides of the viewer
6
for respectively reproducing surround signals. And these apparatuses are arranged in a room confined by four walls WF, WB, WR, and WL, as typically shown in FIG.
16
.
In the multichannel sound signal reproducer, the loudspeakers
2
L and
2
R respectively reproduce left and right channel sound signals, and the loudspeaker
11
mainly reproduces dialogues spoken by characters on a TV screen, for example. The normal location of the lines is greatly improved by providing the loudspeaker. Further, the loudspeaker
4
L and
4
R reproduces a surround channel signal representing reverberations and a reflected sound. A sound field at which the viewer
6
feels as if he or she was present is formed by sounds radiated from the loudspeakers.
In the above-mentioned conventional construction, however, the center channel signal is reproduced from the loudspeaker
11
located on the TV
5
, so that a sound image is formed around a position indicated by B, as shown in FIG.
17
. On the other hand, a picture image is reproduced by the TV
5
under the loudspeaker
11
. Therefore, the position of the sound image and the position of the picture image are separated from each other, thereby giving an uncomfortable feeling to the viewer
6
.
As a method of solving such points, it is considered that two loudspeakers
12
for respectively reproducing center channel signals are located on both the right and left sides of a TV
5
in the vicinity thereof, as shown in FIG.
18
. In such construction, the center channel signals are synthesized upon being respectively radiated from the loudspeakers
12
A and
12
B located on the right and left sides of the TV
5
, so that a sound image is formed in the center (C) between the two loudspeakers
12
A and
12
B. Consequently, it is possible to perform reproduction in which the positions of the sound image and a picture image coincide with each other.
In the construction shown in
FIG. 18
, however, when the viewer
6
views a screen of the TV
5
in a position shifted leftward, as indicated by
6
a,
for example, the sound image on a center channel is also shifted to a position indicated by Ca, thereby giving an uncomfortable feeling to the viewer
6
. Further, the loudspeakers
2
L and
2
R for respectively reproducing the left and right channel sound signals must be respectively located outside the loudspeakers
12
, so that large spaces for installation are required on the right and left sides of the TV
5
. If there are a lot of loudspeakers on the right and left sides of the screen, the picture image may be visually prevented from being viewed.
In order to avoid such points, JP-A-4-270600 discloses that two loudspeakers
12
A and
12
B for respectively reproducing center channel signals are arranged above and below a TV
5
, as shown in FIG.
19
. If the loudspeakers
12
A and
12
B are thus arranged, a sound image is formed in a position substantially in front of the TV
5
indicated by D, thereby making it possible to perform reproduction in which the positions of the sound image and a picture image coincide with each other. In this construction, however, large spaces for installation are required both above and below the TV
5
.
As means for solving the above-mentioned problems, the inventors and others of the present invention have proposed a loudspeaker for reproducing a center channel signal utilizing characteristics in acoustic psychology in JP-A-8-47097 and JP-A-8-130794. In the publications, it is made clear that a particular band in a frequency band of not less than approximately 4 kHz, and particularly a band in a range of approximately one octave centered around 6.3 kHz is important in recognizing the positions above and below a sound source as the acoustic characteristics of human beings. The contents proposed in the publications are applications of the characteristics in acoustic psychology and “Effect of visual priority” described in “Experiments on the interaction between a sound image and a video image” published by Komiyama, Nakabayashi, Nikaido, et al. (Material in Society for Acoustic Research, 1981), for example.
In JP-A-8-47097, each of the loudspeakers located above and below a picture image reproducer in the vicinity thereof comprises as main components sound pressure attenuating means for suppressing sound pressure in the vicinity of 6.3 kHz, and a main speaker connected thereto, and further comprises a sub-speaker located, facing in a direction different from the main speaker, and band passing means connected thereto for supplying a frequency band in the vicinity of 6.3 kHz. That is, the loudspeaker is so constructed that a sound having a frequency of 6.3 kHz is removed from the main speaker for reproducing a direct sound, and its band is reproduced as a diffused sound utilizing reflection from a rear wall or the like by the sub-speaker. As a result, the position of a sound source of a center channel signal is not easily recognized. A viewer feels as if a sound image was drawn to a TV screen due to the effect of visual priority and coincided with a picture image.
In this construction, however, when the distance from the rear wall is large or there is no wall, the level of a reproduced sound from the sub-speaker becomes low, so that the level in a high frequency region is liable to be insufficient as the entire reproduced sound. In order to improve this point, it is considered that the sub-speaker is provided on a ceiling surface. As apparent from recent experiments, however, if a sound having a frequency in the vicinity of 6.3 kHz is reproduced toward the ceiling of a room, the viewer feels as if the position of the sound source was not only clarified but also moved further upward.
On the other hand, in JP-A-8-130794, a sub-speaker for reproducing a sound having a frequency in the vicinity of 6.3 kHz and a main speaker for reproducing a sound having a frequency other than the frequency in the vicinity of 6.3 kHz are constructed as separate cabinets, the smaller sub-speaker being located above a picture image reproducer such that a sound radiating axis of its speaker unit is directed backward, and the main speaker being located below the image reproducer. In such construction, it is possible to perform reproduction in which a picture image and a sound image coincide with each other utilizing characteristics in acoustic psychology, as in JP-A-8-47097. However, the construction requires that loudspeakers are located in two positions, so that wiring becomes complicated. Further, the distance from a rear wall is important in order to keep the balance in a frequency band of a reproduced sound, as in JP-A-8-47097.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned conventional problem, and has for its object to provide, for reproducing a center channel signal, a loudspeaker capable of
Fukuhara Suemei
Kuramitsu Isao
Mizutani Toshiyuki
Omori Tatsuya
Mei Xu
Pendleton Brian
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