JPS5413320

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DESCRIPTION JPS5413320
Description 1, title of the invention
Bass reflex type speaker device
3. A detailed description of the invention The present invention relates to a loudspeaker
apparatus configured to have an LC lattice type circuit placed on the input end of a bass reflex
loudspeaker, and to improve the output sound pressure level in the low band of the loudspeaker
Purpose. Hereinafter, the bass reflex type speaker device of the present invention will be
described with reference to the drawings of the embodiments. FIG. 1 shows the basic principle of
the bass reflex type speaker device of the present invention, in which 1 is a signal source and aa
'is an input terminal 1. As shown in FIG. bb / is an output terminal, L and C are inductances and
capacitors constituting the lattice circuit 2 and capacitors 2 Ro and Ro are loads such as
speakers. Assuming that the voltage between the input terminals a and a 'is ei and the voltage
between the output terminals b and b is 00, the following equation is established. And ω 1 is
also the lower antiresonant frequency of the bass reflex speaker. When the absolute value of
equation (1) is taken and rewritten, it is represented as the following equation. In the case where
Z0 = R0 in the equation (2), the equation (2i1 indicates that EndPage: 13-1-7 'indicates that the
magnitudes of the eo and ei are the same. Also, if z0 <Ro, the denominator of equation (2)
becomes smaller than 1. That is, equation (2) is obtained, which indicates that the output e0
becomes larger than the input ei. To summarize the above, the resonant frequencies of L and C
constituting the grid circuit are tuned to the low antiresonance frequency ft of the bass reflex
speaker, and the characteristic impedance of the grid circuit is equal to the voice coil resistance
of the speaker If it is increased, the output can be made equal to or larger than the input. FIG. 2
shows an embodiment of a bass reflex type speaker device utilizing the above principle. In FIG. 2,
parts denoted by the same reference numerals as in FIG. 1 have the same functions, and in the
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dotted lines are the bass reflex type loudspeakers 3 (the isometric circuit of the bass reflex type
loudspeaker 3 showing the D1 equivalent circuit is well known Although the description is
omitted here, it goes without saying that the impedance of the equivalent circuit is as shown in
FIG. Therefore, if the LC lattice type circuit 2 is connected to the input end of the bass reflex type
speaker 30 and the resonance frequency of the LC lattice type circuit 2 is located near the lowfrequency antiresonance frequency fr of the bass reflex type speaker 3 The output sound
pressure level in the low range of the bass reflex type speaker can be improved. As described
above, according to the present invention, since the LC grid circuit having a resonance frequency
near the low frequency antiresonance frequency of the bass reflex speaker is connected to the
input end of the loudspeaker, the low bass reflex speaker The output sound pressure in the
region can be increased to realize an excellent bass reflex effect.
Moreover, in general, in the speaker, the electrical input impedance rises at the low frequency
resonance point of the mechanical system, which reduces the power applied from the signal
source to the speaker and causes the apparent efficiency to decrease. According to the invention,
since the bass reflex effect of the bass reflex type speaker itself and the bass reflex effect of the
LC lattice type circuit can be combined to obtain a double bass reflex effect, it is possible to
achieve six pages, so the output sound pressure is significantly improved. Effect is obtained. In
addition, the LC grid type circuit can increase the sound pressure in the low range of the speaker
without using an amplification element, which is advantageous also from the circuit
configuration.
4. Brief description of the drawings FIG. 1 is a circuit diagram for explaining the principle of the
bass reflex type speaker device according to the present invention, FIG. 2 is an equivalent circuit
diagram showing one embodiment of the bass reflex type speaker device according to the
present invention, FIG. 3 is a diagram showing resonance and antiresonance frequency
characteristics of the bass reflex type speaker shown in FIG. 1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ... ..... Output terminal.
Name of agent Attorney Nakao Toshio Nakano has 1 person Figure 2 Figure 3 EndPage: ２
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