Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Having acoustic wave modifying structure
Reexamination Certificate
2000-06-22
2003-11-25
Tran, Sinh (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Having acoustic wave modifying structure
C381S388000
Reexamination Certificate
active
06654472
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a speaker system in a display, and more particularly, to a speaker system in a display, in which a structure of the speaker system is changed to a duct change type, for easy phase inversion of a particular frequency of sound generated from a back surface of a speaker.
2. Background of the Related Art
A related art speaker system in a display and operation thereof will be explained with reference to FIG.
1
.
Referring to
FIG. 1
, the related art speaker system of a track type is provided with a track type speaker
1
(hereafter called as “speaker”), and a rear sound box
2
in rear of the speaker
1
. The speaker has a frame
102
, a gasket
103
inside of the frame
102
, an edge
104
fitted to form a ring on an inside of the gasket
103
, a cone paper
105
attached to an inside of the edge
104
in a form of a cone. There is a duct
3
a
in the rear sound box
2
as a unit therewith for inverting a phase of the sound generated from a back surface of the speaker
1
. There is a cylindrical speaker system mount
106
on a top of the speaker
1
for coupling the speaker system to a speaker system fastening boss
5
fixed on a cabinet(not shown) of the display, and the speaker system mount
106
has anti-vibration rubber
6
for preventing a vibration transmitted from the speaker system to the cabinet.
The operation of the foregoing related art speaker system will be explained.
When the speaker system is in operation, there is a sound (“A” in the drawing) of a certain frequency band is generated in a front surface of the speaker
1
. And, there is another sound (“-A” in the drawing) having the same frequency with, but having a phase opposite to the sound “A” is generated in the back surface of the speaker
1
. Therefore, it is required to invert the phase of the sound “-A” generated in the back surface of the speaker
1
. The phase inversion is done as the sound “-A” generated in a back surface of the speaker
1
passes through the duct
3
a
, but for only a portion of the sound (“-A”) with a particular frequency. The sound with a particular frequency from the duct
3
a
having an inverted phase(represented as “B” in the drawing) reinforces the sound “B” with an identical frequency among the sound “A” from the front surface of the speaker
1
, thereby providing a low sound reinforcing effect. The frequency “f” of the sound from the duct
3
a
can be expressed with an equation, below.
f
=
1
2
π
Sc
Mp
Where, Mp denotes mass of air in the duct, which is a function of a length and a sectional area of the duct, and Sc denotes a stiffness of the sound box, which is a function of an internal volume. Therefore, if dimensions of the rear sound box are fixed, that is the internal volume Sc is constant, the frequency of the sound from the duct
3
a
is fixed depending on the length and sectional area of the duct.
However, the formation of the duct
3
a
as a unit with the speaker system in the related art causes the following problems.
The related art speaker system can only invert a particular frequency, to require a new rear sound box
2
when it is desired to invert other particular frequency by changing the length or sectional area of the duct
3
a
, that is impossible as the related art speaker system has unitary duct
3
a
and sound box
3
. And, even if a design of the rear sound box
2
itself is changed for fabricating a new rear sound box
2
in an intention to provide a longer duct
3
a
, the provision of the longer duct as much as wanted is very difficult since a drawing out angle of a mold should be taken into consideration.
Moreover, the backward exit of the duct
3
a
from the rear sound box
2
in the related art speaker system causes a sound pressure drop, which weakens a reinforcing power for the sound generated in the front surface.
In summary, the unitary duct
3
a
and sound box
3
permits no change of the duct only, and the backward exit of the duct
3
a
from the rear sound box
2
causes a loss of the sound pressure.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a speaker system in a display that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a speaker system in a display, in which a duct only can be changed with easy for inverting a phase of a desired frequency, and an inverted sound is made to be discharged to forward for eliminating a sound pressure loss.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the speaker system in a display includes a speaker for presenting a sound, a rear sound box coupled to a back of the speaker, and a changeable duct disposed to pass through a front surface of the speaker and to be positioned in the rear sound box, and detachably fitted to the speaker, for inverting a phase of a particular frequency of sound among sound generated in a back surface of the speaker, and presenting the inverted sound.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4201274 (1980-05-01), carlton
patent: 4997057 (1991-03-01), Furukawa
patent: 5115473 (1992-05-01), Yamagishi et al.
patent: 5436977 (1995-07-01), sato
patent: 5513270 (1996-04-01), Lewis
patent: 5550921 (1996-08-01), freadman
patent: 5825900 (1998-10-01), Jeon
patent: 9074595 (1997-03-01), None
patent: 1019990198290 (1999-02-01), None
Fleshner & Kim LLP
LG Electronics Inc.
Tran Sinh
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