JPS5838710Y2 - speaker - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a speaker that can expand the bass range reproduction area.

FIG. 1 shows a cross section of a conventional speaker.

In FIG. 1, 1 is a cylindrical yoke with a bottom surface, 2 is a magnet fixed to the bottom surface inside the yoke 1, 3 is a center pole fixed to the top surface of the magnet 2, and 4 is an opening on the top surface of the yoke 1. An annular magnetic gap is formed between the inner circumferential surface of the plate 4 and the outer circumferential surface of the center pole 3.

As shown in FIG. 2, the plate 4 has four through holes 5 formed on the same circumference.

6 is an annular frame fixed on the plate 4, and 7 is a flat diaphragm, and this flat diaphragm 7 is supported by the frame 6 via an edge member 8.

A coil bobbin 9 is fixed to the lower surface of the flat diaphragm 7, and a voice coil 10 is wound around the coil bobbin 9.

This voice coil 10 is arranged in the magnetic gap section.

FIG. 3 shows a mechanical equivalent circuit of the conventional speaker shown in FIG.

Fv is the driving force by the voice coil 10, RME is the electromagnetic braking resistance by the voice coil 10, Mo is the mass of the diaphragm 7, RD is the resistance of the vibration system, CD is the compliance of the vibration system by the edge member 8, MMA is the radiation mass, RMA is the radiation mass, MHI is the acoustic mass of the through hole 5 made in the plate 4, C is the back compliance due to the air chamber a at the top of the plate 4, and CB□ is the back compliance due to the air chamber a at the bottom of the plate 4. show.

Normally, the air chamber a is smaller than the air chamber A, and CBl<CB2.

The sound pressure characteristics of the speaker shown in FIG. 1 have stepped characteristics as shown in characteristic B of FIG.

This is because the size of the through hole 5 is small, so in the low frequency range, the mass of the through hole 5 enters in series, reducing efficiency.

far is m... CB indicates the anti-resonant frequency caused by CB2, above which it is reproduced with high efficiency.

Further, the characteristic when the through hole 5 is completely closed is shown as A in FIG. 4.

In this case, the compliance of the rear surface of the diaphragm is small because only the air chamber a is F), and the low frequency characteristics deteriorate.

On the other hand, if the through hole 5 is made larger, the characteristics will be as shown in C in Fig. 4, but the play 1 will be
The through hole 5 could not be made larger because the yoke width of -4 became narrower, the magnetic flux density increased, magnetic saturation occurred, the magnetic flux density of the magnetic gap decreased, and the sound pressure of the speaker decreased.

The present invention eliminates the above-mentioned conventional drawbacks and provides a speaker that can expand the bass range reproduction area without causing magnetic saturation.An embodiment of the present invention will be described below with reference to FIG. do.

FIG. 5 shows a plate 4 used in the speaker of the present invention.

This plate 4 has a center hole 11 with a radius a, and four fan-shaped through holes 12 are formed on a concentric circle with a radius r.

This fan-shaped through hole 12 has a width that is equal to the width of the plate 4.
The through-hole 12. is formed on a concentric circle with a radius r and becomes smaller toward the center of the hole 12. Length of yoke portion other than l = l l+
It is formed so that l 2+ l 3 + l 4 is 1=2πa.

In this way, when the fan-shaped through holes 12 are formed in the plate 4, magnetic saturation of the plate 4 does not occur, and the reproduction area of the bass range can be expanded.

FIG. 6 shows another embodiment of the present invention, in which the radius r1
．． r2. One hole 13 with diameter d is formed on the concentric circle of r3.
6 pieces, 8 pieces, 4 pieces formed, 2yra=2y
rr-nd (n: the number of through holes formed on concentric circles).

FIG. 7 shows still another embodiment of the present invention, in which a V-shaped recess 14 is formed from the outer circumference side of the plate 4, and this recess 14 has a sector-shaped shape in FIG. This is equivalent to the through hole 12 of .

As mentioned above, in this invention, the maximum value of the cross-sectional area on the concentric circle where the through-hole of the plate is formed is almost the same as the area of the inner peripheral surface of the plate, so that magnetic saturation does not occur and the low frequency reproduction area This has the advantage of being able to expand the

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional speaker, Fig. 2 is a top view of the plate of the same speaker, Fig. 3 is a mechanical equivalent circuit diagram of the same speaker, Fig. 4 is a sound pressure frequency characteristic diagram of the same speaker, 5
6 and 7 are top views of plates in embodiments of the present invention, respectively. 4...Plate, 12...Through hole, 1
3...Through hole, 14...Recess.

Claims (3)

[Scope of utility model registration request] (1) In a speaker in which a through hole is formed in an annular plate constituting one magnetic pole of a magnetic gap, the through hole is formed on a concentric circle of the plate, and the maximum cross-sectional area on the concentric circle in which this through hole is formed. A speaker whose value is approximately the same as the area of the inner peripheral surface of the plate. (2) Utility Model Registration The speaker according to claim 1, in which a fan-shaped through hole with a narrow width is formed on the concentric circles of an annular plate at the center of the plate. (3) Utility Model Registration The speaker according to claim 1, wherein through holes are formed on a plurality of concentric circles of an annular plate.