Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Mounting or support feature of housed loudspeaker
Reexamination Certificate
2000-05-10
2003-01-07
Le, Huyen (Department: 2743)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Mounting or support feature of housed loudspeaker
C381S345000, C381S349000
Reexamination Certificate
active
06504939
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a loudspeaker system, and more particularly to a technique directed at improving the quality of sounds.
2. Brief Description of the Prior Art
In the conventional loudspeaker systems, importance is commonly attached to the enclosure sealing properties.
The reason is that any sound pressure leakage from the enclosure may adversely affect the frequency characteristics.
More specifically, sound waves leaking from the enclosure may interfere with direct sounds from the loudspeaker system and disturb the frequency characteristics. In particular, sound waves leaking from the site apart farther from the loudspeaker system may often have the same sound pressure phases within the interior of the enclosure, resulting in an acute interference.
It is therefore an inviolable rule in typical mounting of the loudspeaker unit on the enclosure baffle to keep the sealing at the mounting surfaces. This mounting is carried out in a textbook manner.
As can be seen in FIGS.
25
(A) and
25
(B) for example, a loudspeaker unit
1
is mounted such that the internal face of a flange portion
2
at its peripheral portion comes into intimate contact with the front face of a baffle plate
4
of an enclosure
3
. Alternatively, the loudspeaker unit
1
is mounted such that the external face of the flange portion
2
comes into intimate contact with the rear face of the baffle plate
4
.
In general, the bass characteristics of the loudspeaker system are restricted by the lowest resonance frequency of the loudspeaker unit and the requirement for reproduction of the unit lowest resonance frequency is to impart a sufficient capacity to the unit mounted enclosure. In the conventional loudspeaker systems attaching importance to the enclosure sealing properties, however, the action on the diaphragm of inertial vibrations of the air spring within the enclosure may adversely affect the low-frequency characteristics and transient characteristics of the loud speaker system. In particular, if the mounting capacity is smaller than the enclosure capacity required by the loudspeaker unit, then the low-frequency characteristics may suffer a remarkable damping.
A loudspeaker unit having a large-diameter diaphragm is suitable for the bass reproduction although use of the large-diameter diaphragm may lead to an increase of the enclosure capacity, rendering an enlargement in dimensions of the loudspeaker system inevitable.
For this reason, the typical loudspeaker system intended for the bass reproduction is apt to add to its size and weight, resulting in high costs and low handling properties.
With a view to solving such deficiencies and reducing the system size, there have been proposed a system using bass reflex, a resonance chamber or an acoustic tube for loading, a seal-up system having sound absorption materials filled into the interior thereof, and a system making corrections based on output detection such as motional feedback and including an electronic circuit such as an equalizer. All of them have however caused any complications instructure, resulting inevitably in arise of fabrication costs. In such cases, the systems had tendencies of the quality of sounds proper thereto.
Hitherto known as the loudspeaker system cabinet (enclosure) is an R-J cabinet of a type in which as illustrated in
FIG. 26
a loudspeaker unit
5
fitted to a supplementary baffle plate
6
is mounted on a baffle plate
8
at the front of a cabinet (enclosure)
7
in a spaced apart manner.
In this R-J cabinet, however, air passages allowing a communication between the interior and exterior of the cabinet
7
open to opposed side ends of an opening
9
of the baffle plate
8
, with the result that in spite of its improved bass characteristics the output sound pressure levels in the mid-frequency band will lower with its characteristics having peaks in the vicinity of the bass reproduction limit frequency.
In the past, there has also been proposed a configuration in which a partition is positioned behind the diaphragm spaced by a predetermined distance apart from the diaphragm so as to define an acoustic space therebetween, the inner periphery of the acoustic space leading into the space within the loudspeaker box, the outer periphery of the acoustic space opening to the front face of the loudspeaker box by way of an air vent ring (see Japanese Patent Laid-open Pub. No. Hei2-195796).
This configuration allows the space defined between the partition and the diaphragm to act as a duct for effectively guiding the bass reproduction outputs of the loudspeaker and to enhance the basses since the space at its inner periphery leads into the space within the loudspeaker box and at its outer periphery opens to the front face of the loudspeaker box.
It is however difficult to readily apply this technique to the existing loudspeaker system because the loudspeaker unit itself needs to have an unique specification due to its configuration in which the partition and the air vent ring are integrally mounted on the diaphragm, i.e., the cone to make up the loudspeaker system thereby forming the above space portion.
At the same time, the structure of the cone is also complicated with its increased weight, disadvantageously adding to costs.
Furthermore, due to its bent configuration of the space portion, a smooth radiation of air within the enclosure is not achieved, rendering it difficult to effectively prevent any influence on the diaphragm of the inertial vibrations of the air spring within the interior of the enclosure.
SUMMARY OF THE INVENTION
The present invention was conceived in order to solve the conventional problems as set forth hereinabove. It is therefore the object of the present invention to provide a simple improved attachment structure to the baffle plate of the enclosure of the loudspeaker unit to thereby achieve a reduction in size and weight of the loudspeaker system and achieve an enhancement in the low-frequency characteristics and transient characteristics.
In addition to the above object, it is another object to ensure an easy and secure adjustment of the gaps formed along substantially the overall inner perimeter of the opening in the baffle plate between the rear face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate, to thereby achieve an enhancement in the bass characteristics and an improvement in the quality of sounds for instance.
The loudspeaker system according to a first aspect of the present invention can satisfy items (1) to (4) which follow.
(1) To enhance the low-frequency band through radiation of resonant sounds within the interior of the enclosure.
(2) To improve the transient characteristics over the full reproduction range to acquire a free, easy and gloomless quality of sounds through the reduction of influences on the diaphragm of inertial vibrations of air springs within the interior of the enclosure.
(3) To achieve more effectively an improvement in the quality of sound through effective reduction of resistance to which the coned paper is subjected as a result of a variation in the air pressure within the interior of the enclosure.
(4) To enhance the bass frequency characteristics and simultaneously prevent any turbulence of characteristics at the other frequencies.
To this end, according to the first aspect of the present invention, there is provided a loudspeaker system including an enclosure and a loudspeaker unit adapted to be fitted to an opening in a baffle plate at the front of the enclosure, wherein around the outer peripheral site of the loudspeaker unit there are formed predetermined air passages which extend along substantially the overall inner perimeter of the opening in the baffle plate, for allowing a communication between the interior and exterior of the enclosure.
It has been found out that in the woofer unit or full-range unit, the optimal value can be conferred on the spatial volume provided equi-angularly between the periphery of the woofer unit frame and the b
Creighton Wray James
Le Huyen
Narashimhan Meera P.
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