JPS6340958Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a composite electroacoustic transducer in which two sets of electrodynamic electroacoustic transducer units are combined to improve acoustic characteristics.

The composite electro-acoustic transducer of this invention has first and second electro-dynamic electro-acoustic transducer units whose diaphragms have different lowest resonant frequencies. The front surface of the diaphragm on the side of the second electrodynamic electroacoustic transducer unit is formed on the wall surface of a closed space and acoustically coupled to the wall surface of the closed space.

Hereinafter, the composite electroacoustic transducer of this invention will be explained based on an example with reference to FIGS. 1 and 2. 1st
The figure is an end view showing an embodiment of the composite electroacoustic transducer of this invention. The magnetic circuit of the first electrodynamic electroacoustic transducer unit is constructed by sequentially placing a ring-shaped magnet 2 and a ring-shaped top plate 3 on a bottom plate 1 having a center pole erected in the center. A magnetic gap is formed between the inner circumferential wall and the outer circumferential wall of the center pole portion of the bottom plate, in which the voice coil 4 is disposed. A suitable number of through holes 5 are inserted into the magnetic circuit formed in this way.
A frame 5 having a, 5a, . . . is attached thereto. A diaphragm 6 has a voice coil 4 wound around a bobbin attached to its center, and its peripheral edge is attached to the edge of the frame 5 so that the voice coil 4 is placed in the magnetic gap. be.

The magnetic circuit of the second electrodynamic electroacoustic transducer unit is constructed by sequentially placing a ring-shaped magnet 8 and a ring-shaped top plate 9 on a bottom plate 7 with a cylindrical center pole set up in the center. A magnetic gap is formed between the outer peripheral wall of the ring-shaped top plate 9 and the inner peripheral wall of the ring-shaped top plate 9, in which the voice coil 11 is arranged. Frame 10 in this magnetic circuit
is attached. A diaphragm 12 in which a voice coil 11, which is a coil wound around a bobbin, is attached to the center.
The peripheral edge portion of the voice coil 11 is attached to the stepped portion of the frame 10 so that the voice coil 11 is disposed in the magnetic gap. The outer edge of the lower surface of the frame 5 and the outer edge of the upper surface of the frame 10 are closely attached and fixed.

When formed into a composite electroacoustic transducer in this way, a closed space surrounded by the front surface of the diaphragm 12, the inner surface of the frame 10, and the back surface of the diaphragm 6 is formed, and the diaphragm 12 and the diaphragm 6 form a closed space. Stiffness S
acoustically coupled via. Compared to the lowest resonant frequency of the first electrodynamic electroacoustic transducer unit side diaphragm 6, the second electrodynamic electroacoustic transducer unit side diaphragm 1
Lower the lowest resonant frequency of voice coil 4.
When an input signal for sound reproduction is supplied to the voice coil 11, the first electrodynamic electroacoustic transducer unit produces a range from the lowest resonant frequency of the diaphragm 6 to the treble limit, as shown in the reproduced sound pressure frequency characteristics shown in FIG. The second electrodynamic electroacoustic transducer unit reproduces sound from the lowest resonant frequency of the diaphragm 6 toward the high frequency range, but this is bridged by the stiffness S of the closed space and is approximately -6 db/oct. The sound reproduction level in the treble range decreases as the slope increases. The reproduced sound pressure frequency characteristics are smoother and have fewer peaks and dips than the reproduced sound pressure frequency characteristics when using only the second electrodynamic electroacoustic transducer unit due to the closed space. Since it decreases at about -6 db/oct, it is easy to synthesize it with the reproduced sound pressure frequency characteristic of the first electrodynamic electroacoustic transducer unit, which in turn improves the frequency range of the reproduced sound pressure frequency characteristic of the composite electroacoustic transducer. The reproduction sound pressure level is leveled out.

FIG. 2 is an end view showing another embodiment. 1st
The closed space of the embodiment shown in the figure is another embodiment in which the back surface of the first electrodynamic electroacoustic transducer unit side diaphragm 6 is divided into an inner side 6a and an outer side 6b of the voice coil 4. In this embodiment, the sound waves from the diaphragm 12 are propagated over the entire back surface of the diaphragm 6, so that the entire surface of the diaphragm 6 is amplitude-modulated in the same phase, thereby reducing amplitude modulation distortion.

[Brief explanation of the drawing]

Figure 1 is an end view showing an embodiment of this invention;
The figure is an end view showing another embodiment, and FIG. 3 is a reproduced sound pressure frequency characteristic diagram.

Claims (1)

[Claims for Utility Model Registration] 1. First and second electrodynamic electroacoustic transducer units having different lowest resonant frequencies of the diaphragms are connected to the rear surface of the diaphragm on the side of the first electrodynamic electroacoustic transducer unit, and A composite electro-acoustic transducer in which the front surface of the diaphragm on the side of the bi-dynamic electro-acoustic transducer unit is configured and acoustically coupled to the wall of a closed space. 2. A utility model characterized in that the lowest resonant frequency of the diaphragm on the second electrodynamic electroacoustic transducer unit side is lower than the lowest resonant frequency of the diaphragm on the first electrodynamic electroacoustic transducer unit side. Scope of Registration: Composite electroacoustic transducer according to item 1. 3. Practical use characterized in that the rear surface of the diaphragm on the side of the first electrodynamic electroacoustic transducer unit is acoustically coupled to the inside and outside of a cylindrical voice coil bobbin attached to the center of the rear surface. A composite electroacoustic transducer according to claim 1 or 2 of the patent registration claim.