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Specification 1, Title of Invention
3. A detailed description of the invention The present invention relates to a speaker system that
performs narrow band reproduction using a mechanical, acoustic or electrical low pass filter, a
vibration system mass of the speaker unit, a cabinet for housing the speaker unit, and a low pass
filter The speaker system of high efficiency can be realized by appropriately selecting the
compliance of. In the conventional narrow band speaker system, the reproduction band is simply
narrowed by a filter constituted by an electric circuit, and a device for increasing the efficiency of
the speaker system is not particularly made. The present invention is intended to increase the
efficiency of a narrowband speaker system by increasing Q at the lowest resonant frequency
(hereinafter referred to as light) and high cutoff frequency (hereinafter referred to as fH). An
embodiment of the present invention will be described below with reference to the drawings. FIG.
1 shows EndPage: 1 showing a speaker unit used in the present invention. In FIG. 1, 1 is a center
pole, 2 is a magnet, 3 is a plate, 4 is a frame, 5 is a voice coil bobbin, 6 is a voice coil, 7.8 is a
damper, 9 is a diaphragm, '10 is an edge, 11 is an The mechanical filter is made of a mechanical
elastic material such as rubber or bashi, and the bobbin 5 and the vibrator 9 are coupled via the
mechanical filter 11. FIG. 2 shows sound pressure frequency characteristics of the speaker
system. In FIG. 2, a shows the sound pressure characteristics when the normal low-pass filter is
made into a closed cabinet and the low-pass is made flat-max, with a normal speaker unit having
no mechanical, acoustic or electrical low-pass filter enclosed. . Note that, as shown in FIG. 2A, the
flat max refers to a characteristic in which the flat characteristic of the high region is extended to
the low region as it is and the Q is inclined near f0 with no rise and fall. By the way, Q in fo
(hereinafter referred to as "false") is expressed by false -V 1 (1) M: vibration system mass CB:
compliance of cabinet. Therefore, if the vibration system mass of the speaker unit, for example,
the mass of the diaphragm 9 in FIG. 1 is increased in the state where the sound pressure
characteristic a is obtained, Q in fo can be increased. However, in this case, the efficiency
decreases as the vibration system mass increases, resulting in the sound pressure characteristics
as shown in FIG. Then, it can be seen that the sound pressure characteristic of the present
invention has a higher Q than the flat max b '. Further, as is clear from the equation (1), not only
increasing the vibration system mass M but also decreasing the cabinet compliance CB can
similarly increase Q in fo.
On the other hand, when the speaker unit having the mechanical filter 11 as shown in FIG. 1 is
used, this mechanical filter 11 does not work as a low pass filter, and the sound pressure
characteristic in the high region is attenuated, as shown in FIG. It becomes a sound pressure
characteristic. At this time, Q (hereinafter referred to as QH) at fH of the low-pass filter is
expressed by QH = Jy-m7... (2) M: vibrational system mass CF: compliance of the filter. Therefore,
also in this case, if the vibration system mass M is increased, QH becomes higher than the flat
max. Further, as apparent from the equation (2), it is possible to increase Q in the case where the
compliance CF of the filter 11 is reduced. -In order to increase fH, it is necessary to reduce CF, so
in this case, Q is naturally increased. As apparent from the above description, if the vibration
system mass M and the compliance CB of the cabinet are properly selected to increase Q in fo,
and the compliance CF of the filter 11 is appropriately selected to increase Q in fH, the second A
narrow-band sound pressure characteristic as shown in FIG. Sound pressure characteristics as
shown in FIG. 2 d can be obtained if the sound pressure characteristics can be obtained by
storing them in a nupika unit ヲ path reflex plate type cabinet or a tha hard cone type cabinet.
The obtained loudspeaker system ヲ path reflex type mata can obtain the sound pressure
characteristics as shown in FIG. 2e if it is housed in a cabinet of the drone cone type. Therefore, a
speaker system with even higher efficiency can be realized by using a speaker-flex system or a
drone cone system as the speaker cabinet. The low pass filter may be a mechanical filter as
shown in FIG. 1 or an acoustic filter using an air damper. Also, it may be an electrical filter
incorporated in a network connected to the speaker unit. In this case, if the value of the capacitor
corresponding to the compliance of one machine (first arrival) filter is appropriately selected, the
same effect as the above embodiment can be obtained. Finally, it is an EndPage: 2 system for
obtaining the sound pressure characteristics a-e of FIG. As shown in Table 1 or more, according
to the present invention, in a narrow band speaker system using mechanical, acoustic or
electrical filters, by properly selecting the vibration system mass, the cabinet compliance and the
filter compliance. It is possible to realize a highly efficient speaker system which has not been
achieved conventionally.
4, a brief description of the drawing
FIG. 1 is a cross-sectional view of a speaker unit used in the present invention, and FIG. 2 is a
sound pressure characteristic diagram for explaining the present invention in detail. 1 · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · voice
coil bobbin, 6 · · · ········· Voice coil, 7, 8 ·································· Diaphragm, 1 o ····························· Mechanical
filter. Name of Agent Attorney Nakao and 1 other EndPage: 3