Electrical audio signal processing systems and devices – Binaural and stereophonic – Center channel
Reexamination Certificate
1999-07-08
2002-08-20
Isen, Forester W. (Department: 2644)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Center channel
C381S099000
Reexamination Certificate
active
06438237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a 3D woofer drive circuit, and more specifically, to a 3D woofer drive circuit arranged to drive a woofer which is a speaker for a low frequency range in the center of a 3D sound system.
2. Description of the Related Art
FIG. 3
is a circuit diagram illustrating an example of a conventional 3D sound system relating to a background of the present invention. The conventional 3D sound system
1
shown in
FIG. 3
includes two input terminals
2
a
and
2
b.
Two inductors
3
a
and
3
b
are connected in series between the two input terminals
2
a
and
2
b
. A capacitor
4
is connected between a connection point of the two inductors
3
a
and
3
b
and a ground terminal which is a reference potential. A variable resistor
6
is connected to each end of the capacitor
4
and to two speaker terminals
5
for a woofer.
A capacitor
7
a
and an inductor
8
a
are connected to each other in series between the input terminal
2
a
and the ground terminal, and two speaker terminals
9
a
for an L-channel speaker are connected to each end of the inductor
8
a.
Similarly, a capacitor
7
b
and an inductor
8
b
are connected to each other in series between the input terminal
2
b
and the ground terminal, and two speaker terminals
9
b
for an R-channel speaker are connected to each end of the inductor
8
b.
In this 3D sound system
1
, a woofer is connected to the speaker terminals
5
, an L-channel speaker for medium to high frequency range is connected to the speaker terminals
9
a
, and an R-channel speaker for medium to high frequency range is connected to the speaker terminals
9
b.
In this 3D sound system
1
, an L-channel sound signal is input between the input terminal
2
a
and the ground terminal, while an R-channel sound signal is input between the input terminal
2
b
and the ground terminal. Thus, the low frequency range sound signal among the sound signals in which the L-channel sound signal is synthesized with the R-channel sound signal is converted into sound by the woofer, the medium to high frequency range sound signal in the L-channel sound signal is converted into sound by the medium to high frequency range L-channel speaker, and the medium to high frequency range sound signal in the R-channel sound signal is converted into sound by the medium to high frequency range R-channel speaker.
FIG. 4
is a circuit diagram illustrating another example of a conventional 3D sound system relating to the background of the present invention. A conventional 3D sound system
11
illustrated in
FIG. 4
includes a pre-amplifier
12
. The pre-amplifier
12
is provided with two input terminals
13
a
and
13
b
and two output terminals
14
a
and
14
b.
Two resistors
15
a
and
15
b
are connected in series between the two output terminals
14
a
and
14
b
of the pre-amplifier
12
. A capacitor
16
is connected between the connection point of the two resistors
15
a
and
15
b
and the ground terminal which is the reference potential. Two speaker terminals
18
for the woofer are connected to each end of the capacitor
16
through a main amplifier
17
.
A capacitor
19
a
and a resistor
20
a
are connected in series between the output. terminal
14
a
of the pre-amplifier
12
and the ground terminal, and two speaker terminals
22
a
for the L-channel speaker are connected to each end of the resistor
20
a
through a main amplifier
21
a.
Similarly, a capacitor
19
b
and a resistor
20
b
are connected in series between the output terminal
14
b
of the pre-amplifier
12
and the ground terminal, and two speaker terminals
22
b
for the R-channel speaker are connected to each end of the resistor
20
b
through a main amplifier
21
b.
In the 3D sound system
11
, the woofer is connected to the speaker terminals
18
, the medium to high frequency range L-channel speaker is connected to the speaker terminals
22
a
, and the medium to high frequency range R-channel speaker is connected to the speaker terminals
22
b.
In the 3D sound system
11
, the L-channel sound signal is input between the input terminal
13
a
of the pre-amplifier
12
and the ground terminal, and the sound signal of the R-channel is input between the input terminal
13
b
of the pre-amplifier
12
and the ground terminal. The low frequency range sound signal among the sound signals in which the L-channel sound signal is synthesized with the R-channel sound signal is converted into sound by the woofer, the medium to high frequency range sound signal in the L-channel sound signal is converted into sound by the medium to high frequency range L-channel speaker, and the medium to high frequency range sound signal in the R-channel sound signals is converted into sound by the medium to high frequency range R-channel speaker.
In the 3D sound system
1
illustrated in
FIG. 3
, the impedance of the woofer forming a load is low, and the values of the inductance and the capacitance of the inductors
3
a
and
3
b
, and the capacitor
4
constituting a network for the woofer are increased, the size is increased, and the power must also be considered.
Further, in the 3D sound system
1
illustrated in
FIG. 3
, the variable resistor
6
to regulate the level of the woofer must be impedance-matched with the woofer forming the load, and a specialized variable resistor must be used, its size is large, its cost is high, and the power must also be considered.
In addition, in the 3D sound system
1
illustrated in
FIG. 3
, if the tone of the woofer is to be adjusted, the tone must be adjusted at the woofer itself.
In the 3D sound system
11
illustrated in
FIG. 4
, a plurality of amplifiers including the pre-amplifier and the main amplifier are required to drive the woofer.
Also, in the 3D sound system
11
illustrated in
FIG. 4
, the construction of the driver for the woofer becomes complicated, and the whole system is increased in size and cost.
SUMMARY OF THE INVENTION
Accordingly, in order to overcome the problems described above, preferred embodiments of the present invention provide a 3D woofer drive circuit which miniaturizes a 3D sound system and greatly reduces the cost thereof.
A 3D woofer drive circuit according to preferred embodiments of the present invention for driving the woofer in the center of a 3D sound system includes an impedance element arranged to synthesize an L-channel sound signal with an R-channel sound signal and an amplifier arranged to output to the woofer the sound signal synthesized by the impedance element for driving the woofer.
In the 3D woofer drive circuit of preferred embodiments of the present invention, the impedance element includes a resistor, a capacitor connected to the resistor, and a low pass filter arranged to control the frequency of the sound signal to be output to the woofer by the resistor and the capacitor may be provided. In this case, a variable resistor which also has the function of an attenuator and a tone control may be used as the resistor to be used in the low pass filter.
In the 3D woofer drive circuit of preferred embodiments of the present invention, the L-channel sound signal is synthesized with the R-channel sound signal via the impedance element, the synthesized sound signal is output to the woofer by the amplifier, thus driving the woofer, and the sound signal is converted into sound by the woofer.
In preferred embodiments of the present invention, it is not necessary that the network for the woofer include the inductor and the capacitor, and a plurality of amplifiers to drive the woofer can be eliminated, and the constitution of the 3D woofer drive circuit is thereby greatly simplified. Thus, the 3D sound system is miniaturized and the cost is reduced if the 3D woofer drive circuit of preferred embodiments of the present invention is used in the 3D sound system.
The above-mentioned elements, features, characteristics and advantages of the present invention are further clarified by the following detailed description of preferred embodiments referring to the drawings.
Isen Forester W.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Pendleton Brian Tyrone
LandOfFree
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