JPH10336790A - Speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower a minimum resonance frequency to the low frequency side and to expand a reproduction band of a low-frequency sound without thinning an edge of a small-sized speaker. SOLUTION: A damper 9 of a small-sized speaker is composed airtight and a space part 18a, which is formed in the upper part of the bottom of the damper 9 and a frame, and/or a change in air pressure inside the second space part are added as weight to a cone 10 by way of a pipe 24 that compose two caps 14a and 14b above a voice coil bobbin 8. Thus, a minimum resonance frequency fo is moved to the low frequency side and sensitivity is prevented from lowering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small loudspeaker having an airtight damper, and more particularly to a loudspeaker capable of lowering a low-frequency resonance frequency to a lower frequency.

[0002]

2. Description of the Related Art Conventionally, various types of small speakers have been proposed. FIG. 6 is a side sectional view of the most common small speaker. Speaker 20 of FIG.
Is an inverted T-shaped cross section in which a cylindrical center pole 4a planted in the center and a magnet guide 4b concentrically formed with a stepped portion so as to surround the center pole 4a are formed of a disc-shaped plate material. Yoke 4 and the yoke 4
A magnet 3 having an inner diameter fitted in the magnet guide portion 4b and magnetized in a thickness direction in a joined ring shape;
A ring-shaped plate 1 joined to the upper surface of the magnet 3 with an adhesive or the like and a funnel-shaped frame 7 made of steel or the like fixed on the plate 1 constitute a magnetic circuit of a metal part.

In the concentric magnetic gap 17 between the center pole 4a and the plate 1, a spacer such as kraft paper is provided on the inner periphery of the voice coil bobbin 8 in order to insert the voice coil 8a wound around the voice coil bobbin 8. In the wound state, the voice coil bobbin 8 is inserted into the center pole 4 a from above, and the voice coil 8 a is set so that the position of the voice coil 8 a is disposed in the magnetic gap 17.

A corrugated damper 9 having a corrugated shape is bonded between the outer diameter of the upper end of the voice coil bobbin 8 and the outer periphery of the bottom of the frame 7 with an adhesive or the like. Voice coil bobbin 8
The maximum diameter of the cone 10 is fitted to the outer diameter of the upper end of the
To join.

Further, the outer diameter of the damper 9 is joined to the outer circumference of the bottom of the frame 7, and after the adhesive is dried, the spacer inserted into the inner diameter of the voice coil bobbin 8 is removed. To the upper surface of the cone or the inclined portion of the cone 10.

A lead wire from the voice coil 8a is connected to an input terminal 15 via a tinsel wire 16, and an audio signal is supplied to the voice coil 8a via the input terminal 15. In the above description, the case of assembling the magnet 3 which has been magnetized in advance has been described, but the magnet 3 which is not magnetized may be magnetized in the final assembly stage.

[0007]

The small speaker as described above is generally called a fixed-edge type, in which the flow rate of the pulp water at the edge 13 is reduced to make it thinner than the cone 10 when the cone 10 is made. Speakers are used. In a small speaker 20 having such a fixed edge 13, the cone 10 is lightened,
Is reduced so that the lowest resonance frequency fo is lowered to the lower frequency side.

However, when the fixed edge 13 is made thinner, the sound radiated from the front of the cone 10 and the sound radiated from the back side of the cone 10 are canceled through the thin fixed edge 13 and the lowest resonance frequency is shifted to the lower side. Although it can be lowered, there is a problem that the sound pressure is lowered and the sensitivity is deteriorated.

FIG. 7 shows a gain-frequency characteristic curve 21A, a distortion-frequency characteristic curve 22A, and an impedance-frequency characteristic curve 2 of a small speaker having a fixed edge as described above.
3A, the minimum resonance frequency fo of the small speaker 20 having the cone 10 having the fixed edge 13 as shown in these characteristic curves is approximately 400 Hz, but the resonance peak shows a large value of 86 dB.

In order to eliminate the above-mentioned adverse effects caused by the fixed edge 13, the fixed edge 13 may be thickened so as to reduce the amount of cancellation generated at the fixed edge 13. fo
Is shifted to the high frequency side, the lowest resonance frequency fo rises, it becomes difficult to reproduce by expanding the bass reproduction band, and since the magnet 3 constituting the magnetic circuit is extremely small due to its small size, There is a problem that the sensitivity of the speaker is reduced.

An object of the present invention is to provide a small loudspeaker which has solved the above-mentioned problems. An object of the present invention is to provide a hermetic seal having a fixed edge or a free edge and a damper made of cloth or the like. Without increasing the lowest resonance frequency fo, the additional mass of the acoustic resonance system is added to the cone, and the sensitivity is increased over a relatively wide band near the low-band resonance frequency of the airtight damper. The goal is to get a speaker that can do it.

[0012]

As shown in FIG. 1, a speaker according to the present invention has a damper 9 for holding a cone 10 and a voice coil 8a in an airtight manner as shown in FIG. The air 5a and 5b in the space 18
The double cap is supplied to the double cap through a through hole 2a formed in the lower cap 14b in accordance with the vibration of the cone 10, and acoustic impedance is added to the cone 10 in a low frequency range.

According to the loudspeaker of the present invention, it is possible to provide a loudspeaker in which the low-frequency reproduction band can be expanded by adding only one cap, the sensitivity is raised without increasing the minimum resonance frequency fo of the loudspeaker, and the sound quality is improved. It becomes.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A small speaker according to the present invention will be described below in detail with reference to FIGS. The parts corresponding to the speakers shown in FIG. 6 are denoted by the same reference numerals.

In FIG. 1, reference numeral 20 denotes a small speaker of the present embodiment as a whole. A yoke 4 has a disk-shaped portion made of a plate material such as pure iron, and a column-shaped center pole erected at the center of the disk-shaped portion. 4a and a magnet guide portion 4 comprising a step formed in a disc-shaped portion concentrically with the center pole 4a.
b is formed integrally.

A ring-shaped driving magnet 3 magnetized in the thickness direction of ferrite or the like is bonded on the disc-shaped portion of the yoke 4 via an adhesive. The inner diameter of the ring-shaped driving magnet 3 is fitted and positioned in a step portion of a magnet guide portion 4b formed in a disk-shaped portion of the yoke 4.

The plate 1 is joined to the driving magnet 3. In this case, center gap 4
a, and put it in the drive magnet 3
An adhesive is applied on the upper surface of the gap guide, and the inner diameter of the plate 1 is inserted into the outer diameter of the gap guide to fix the adhesive. The plate 1 is made of pure iron or the like in a disk shape, and is made of a perforated plate having a through hole formed in the center thereof. A voice coil is formed in a magnetic gap 17 formed between the inner periphery of the through hole and the outer diameter of the center pole 4a. 8a is provided.

The metal part of the magnetic circuit is formed by fixing a frame 7 formed in a funnel shape of steel or the like to the plate 1, and the outer periphery of the center pole 4 a and the inner diameter of the magnet 3 are provided below the magnetic gap 17. Second space 18 surrounded by
b is formed.

The voice coil 8 wound around the cylindrical voice coil bobbin 8 is provided in the magnetic gap 17 of the above magnetic circuit.
The voice coil bobbin 8 is held via a damper 9 having a corrugation of a waveform so as to be able to vibrate vertically.

The inner diameter of the damper 9 is the voice coil bobbin 8
Is bonded to the upper end of the frame via an adhesive, and the outer diameter is
Is bonded to the outer periphery of the bottom surface of Further, the inner diameter of the funnel-shaped cone 10 having a free or fixed edge 13 made of paper or the like is joined to the upper outer diameter portion of the voice coil bobbin 8, and the maximum diameter portion of the cone 10 is attached to the periphery of the upper opening of the frame 7 by a gasket. Fix through 12.

At the upper end of the voice coil bobbin 8 or the inclined portion of the cone 10, a lower cap 14b formed in a dome shape with a bonded portion 21 made of a highly airtight material such as aluminum and the like is hermetically sealed at the upper end of the voice coil bobbin 8. Are bonded via an adhesive so as to cover the surface.

Further, the upper cap 1 is formed in a dome shape having a larger radius of curvature than the lower cap 14a, together with the bonded portion 21 with a highly airtight material such as aluminum.
4a covers the lower cap 14b and is spaced apart from the inclined portion of the cone 10 via the bonding portion 21 by an adhesive so that an air tube is formed by the double structure cap with a predetermined gap. Joined.

Further, the tinsel wire 16 is connected to the voice coil 8a, and an audio signal is supplied to the voice coil 8a via the input terminal 15 attached to the frame 7.

By assembling the small speaker as described above, the first space (first cavity) 18a between the damper 9 and the upper surface of the frame 7 or the plate 1 and the second space ( A second cavity 18b is formed.

In the present invention, the upper and lower caps 14a and 14
b is configured as shown in the enlarged sectional view of the main part of FIG.

That is, one or two small through-holes 2a through which air in the first and second cavities 18a and 18b flow are formed substantially in the center of the dome of the lower cap 14b. In the vicinity of the outer periphery of the dome 14a, about one or two small through holes 2b are formed.

Further, the voice coil bobbin 8 is also provided with first and second cavities 18 as shown in the perspective views of FIGS.
A small through-hole 2c through which the air in a and 18b flows may be formed, or the sliding portion groove 19 of the voice coil bobbin 8 may be used without forming the through-hole 2c as shown in FIG. In this case, the opening degree of the sliding portion groove 19 may be adjusted by adjusting the length L of the bobbin reinforcing paper 6 wound between the voice coil 8a and the voice coil bobbin 8. Also, the through-hole 2c or the sliding portion groove 19 formed in the voice coil bobbin 8 is formed.
Can be provided in the first cavity 18a formed in the upper part of the bottom surface of the damper 9 and the frame 7.

As the damper 9, a cloth or a highly airtight material obtained by impregnating a cloth with a synthetic resin material is selected, and, for example, a small through hole 2d for air circulation is preferably provided on the outer peripheral portion of the damper 9 by one. It is made so as to pierce about each.

Although FIGS. 1 and 2 show one damper 9 with corrugation, two airtight upper and lower dampers 9a and 9b are arranged inside the coil bobbin 8 and inside the frame 7 as shown in FIG. You can also do it. FIG.
For example, of the upper and lower dampers 9a and 9b having high airtightness, a small ventilation hole 2d is formed in the upper damper 9a in the valley near the outer periphery of the corrugation, and the lower damper 9b is formed in the valley near the inner periphery of the corrugation. Similarly, a small ventilation hole 2f is formed.

In this case, similarly to FIG. 2, a change in the pressure of the stiffness of the air 5a in the first cavity 18a formed on the lower side of the damper 9 (or the upper and lower dampers 9a and 9b) and the upper surface of the bottom surface of the frame 7 is shown. 2 and FIG.
As shown by an arrow a in FIG. 5, the first hole is sent into the first cavity 18a through the through hole 2d (or 2f) formed in the damper 9 (or the upper damper 9a and the lower damper 9b), and the through hole 2c ( Alternatively, it is sent out into the inner diameter of the voice coil bobbin 8 via the sliding portion groove 19).

Further, this pressure change is formed into a pipe 24 in a gap with the upper cap 14a through the through hole 2a of the lower cap 14b of the double structure, and is sent into the pipe 24. Through this pipe 24, the upper cap 14a
Upper cap 2 through a through hole 2b formed in the outer peripheral portion of
It comes out above b.

Therefore, the air resistance Rm in the pipe 24 is added to the cone 10 so that the lowest resonance frequency fo can be shifted to the lower frequency side, and the pressure change of the stiffness in the first cavity 18a is changed by the damper 9 ( Or 9a and 9b), the voice coil bobbin 8, and the through holes 2d (or 2d and 2f), 2c, 2a, 2 formed in the upper and lower caps 14a and 14b.
Since the light is radiated through the b, the impedance of the dampers 9, 9a, 9b having airtightness can be reduced.

That is, an airtight damper 9 (or 9a, 9b) is formed through a through hole 2b formed in the outer peripheral portion of the upper cap 14a.
Is radiated through the through-hole 2c formed in the voice coil bobbin 8, so that the mass of the vibration system of the speaker is reduced by the air in the pipe 24. By increasing the resistance Rm, the lowest resonance frequency fo is lowered, and the sensitivity of the loudspeaker also increases because the resonance phenomenon is used.

That is, the airtight dampers 9, 9 are formed by the through holes 2b and 2a formed in the upper and lower caps 14a and 14b.
Since the resonance of a and 9b is dumped, the sound quality can be made high sensitivity. FIG. 5 shows a frequency characteristic curve similar to that of FIG. 7 of the present invention, but the lowest resonance frequency fo is 400 Hz in the conventional gain-frequency characteristic curve 21A, but is in the gain-frequency characteristic curve 21B in FIG. 5B. 350H
It has transitioned to z and the low frequency side. Caps 14a and 14
b through the through holes 2b and 2a,
Since the low-frequency impedance of (9a or 9b) can be reduced, it is considered that the sensitivity is lowered by adding the mass, but the peak value is also 86 dB as shown in the frequency characteristic curve diagram of FIG.
To 83 dB. Also, the sensitivity in the high frequency range is 82d.
Those of about B have increased to 87 dB.

In FIG. 4, the through hole 2d is formed only in the upper damper 9a, and the through hole 2f is not formed in the lower damper 9b, so that the through hole 2d is formed between the upper and lower dampers 9a and 9b of the voice coil bobbin 8.
g, and the air 5b sucked from the through hole 2d is passed through the through hole 2g.
And an air resistance Rm is added to the cone 10 by using a pipe effect formed in a gap between the upper and lower dampers 9a and 9b. In this case, it is superimposed on the pipe effect between the two caps, and it is possible to lower the lowest resonance frequency fo to a lower frequency side.

[0036]

According to the loudspeaker of the present invention, the pressure change of the stiffness in the first cavity (space) is added to the cone simply by adding one cap or damper with the same structure as the conventional small loudspeaker. As a result, the additional mass is given, the lowest resonance frequency fo can be lowered, the bass reproduction band can be expanded, the sensitivity can be increased, and the sound quality can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a speaker of the present invention.

FIG. 2 is an enlarged side sectional view of a main part of the speaker of the present invention.

FIG. 3 is a perspective view of a voice coil used in the present invention.

FIG. 4 is a schematic diagram illustrating another configuration of a damper used in the present invention.

FIG. 5 is a frequency characteristic curve diagram of the speaker of the present invention.

FIG. 6 is a side sectional view of a conventional speaker.

FIG. 7 is a frequency characteristic curve diagram of a conventional speaker.

[Explanation of symbols]

1, plate, 2a, 2b, 2c, 2d, 2f, 2g ...
Through hole, 3 ... magnet, 8 ... voice coil bobbin, 8a
... voice coil, 9, 9a, 9b ... damper, 10 ... cone, 14a, 14b ... cap, 20 ... speaker

Continued on the front page (72) Inventor Akihiro Akiyama 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Naoki Watanabe 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Stock In company

Claims (4)

[Claims] 1. A damper for holding a cone and a voice coil is hermetically sealed, and air in a space formed under the damper is doubled through a through hole formed in a lower cap. The speaker is supplied according to the vibration of the cone, and acoustic impedance is added to the cone in a low frequency range. 2. The air supply device according to claim 2, wherein air in a space formed below the damper is supplied into the double cap space through an opening formed in a voice coil between the damper and an upper portion of a frame bottom. The speaker according to claim 1, wherein: 3. The apparatus according to claim 1, further comprising a through hole formed at a substantially central position of the lower cap of the double structure and a through hole formed at an outer peripheral position of the upper cap. The speaker according to claim 2. 4. The loudspeaker according to claim 1, wherein the airtight damper has a double structure, and upper and lower dampers have through holes respectively. .