JPS5854560B2 - speaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speaker having a diaphragm consisting of a cone portion and a dome portion.

This type of speaker unit has a dome portion formed in the center of a diaphragm, a cone portion formed around the dome portion, and a center pole provided with a ventilation hole behind the dome portion.

When this speaker unit is used particularly for reproducing medium and high frequency ranges, a so-called back cavity is usually provided that covers the entire rear surface of the diaphragm.

However, inside this back cavity, the sound waves radiated backward from the cone part and dome part are mixed, and since these sound waves have different frequency characteristics and phase characteristics, they cause interference, resulting in disturbances in frequency percentage, beat noise, etc. This causes deterioration of the reproduced sound.

This seems to be a state similar to cross-modulation, for example.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a speaker that can prevent the interference of sound waves from the cone portion and the dome portion inside the back cavity and obtain good reproduced sound.

Two embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a state in which a speaker unit 1 according to a first embodiment is attached to a front baffle plate 31 of a speaker box.

In this speaker unit 1, the diaphragm is formed from a central dome part 11 and a cone part 12 around it.
Boundary line (circular) between these dome portions 11 and cone portions 12
A cylindrical voice coil bobbin 13 is provided along.

A voice coil 14 is wound around the outer peripheral surface of the end of the bobbin 13.

The annular magnet 15 constitutes a magnetic circuit together with annular yokes 16a and 16bs arranged to sandwich the magnet 15, and a center pole 17 provided at the center of the yoke 16b.

An air gap with high magnetic resistance is formed between the yoke 16a and the center pole 17 of this magnetic circuit, and the voice coil 14 is disposed in this air gap.

A ventilation hole 17a is formed in the center of the center pole 17, and this ventilation hole 17a opens toward the dome portion 11.

A box-shaped back cavity 18 is provided so as to cover the entire rear surface of the diaphragm of this speaker unit.

This back cavity 18 has a sealed structure in which ventilation with the outside is cut off.

Inside this cavity 18, another box-shaped cavity 19 is provided.

The inner cavity of this cavity 19 is the center pole 1
It communicates only with the ventilation hole 17a of the chamber 19.
Ventilation with the outside is cut off and the cavity 18 is kept airtight.

That is, these cavities 18 and 19 are boxes (including cylindrical bodies with bottoms) having a U-shaped cross section and made of, for example, plastic, wood, hard paper, or the like.

The open end of the cavity 18 is adhesively fixed to the inside of the baffle plate 31, and the open end of the cavity 19 is fixed to the annular yoke 16b.
It is glued and fixed to the bottom of the.

By preventing air leakage at these adhesively fixed parts, ventilation with the outside is cut off.

Furthermore, the insides of these nine cavities 18 and 19 are filled with a sound absorbing material such as glass wool.

In the case of the cavity 19 that communicates only with the ventilation hole 17a, it is possible that there is ventilation with the back cavity 18 through the gap between the voice coil 14, the yoke 16':a, and the center pole 17, and it is almost ignored during actual use. No mixing of sound waves occurs.

In the speaker unit 1 having such a configuration, the sound waves radiated backward from the dome part 11 spread only inside the cavity 19, and the sound waves from the cone part 12 spread only inside the cavity 18 (however, outside the cavity 19). Because they are spread out, these sounds do not mix together, thus preventing interference and providing clear and high-quality reproduced sound.

FIG. 2 shows a second embodiment.

That is, FIG. 2 shows an example of the configuration of a speaker system in which a speaker unit 1' for reproducing medium and high frequencies and a speaker 2 for reproducing low frequencies are housed in a speaker box 3.

In this second embodiment, parts that are equivalent to those in the first embodiment described above are given the same numbers and their explanations will be omitted.

In this speaker unit 1', a cylindrical body 4 is used as a cavity inside a box-shaped back cavity 18.

That is, one end of this cylindrical body 4 is adhesively fixed in contact with the outer peripheral surface of the yoke 16b and the surface of the magnet 15, and the other end is crimped or adhesively fixed to the current elastic body 5 such as a rubber packing.

This W elastic body 5 is crimped or adhesively fixed to the inner bottom surface of the back cavity 18.

By maintaining airtightness at both ends of the cylindrical body 4 in this manner, ventilation between the inside of the cylindrical body 4 serving as a cavity and the inside of the back cavity 18 is cut off.

In the case of this second embodiment, as long as airtightness is maintained, there is no need to use adhesive on the annular elastic body 5, so assembly is facilitated.

Further, as in the first embodiment described above, the sound waves from the dome portion 11 and the cone portion 12 are not mixed, and good reproduced sound can be obtained.

Note that the present invention is not limited to the above two embodiments; for example, when only one speaker unit is used, the back cavity 18 can be replaced with a speaker box.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the first embodiment of the present invention, and the second
The figure is a sectional view showing an application example of the second embodiment.

1.1'...Speaker unit, 11...
...Dome part, 12...Cone part, 13...
...Voice coil bobbin, 14...Voice coil, 17...Center pole, 17a...
...Vent hole, 18,19...Cavity, 4
・・・・・・Cylindrical body.

Claims (1)

[Claims] 1. A diaphragm consisting of a cone portion and a dome portion, a center pole provided with a ventilation hole opening toward the dome portion, and a first diaphragm provided so as to cover the back of the entire surface of the diaphragm portion.
A speaker comprising: a cavity; and a second cavity, which is provided airtightly with respect to the first cavity and communicates with the ventilation hole.