JPH0779497A - Speaker - Google Patents

Abstract

PURPOSE:To reduce a temperature rise of a voice coil at a large input by passing a gas flow generated with vibration of a damper whose air-tightness is enhanced through a duct provided to a magnetic circuit section and cooling directly an outer circumferential face of the voice coil. CONSTITUTION:When a diaphragm 20 is moved downward in the operation, the air in a space A is moved to a space B via an air duct 23 and discharged to an external space of a speaker via a 2nd duct 24. Conversely when the diaphragm 20 is moved upward, the air in the external space of the speaker is moved to the space B via the air duct 24 and flows to the space A via the air duct 23. Thus, the gas flow passing through the air duct 23 cools directly the outer circumferential face of a voice coil 18 being a heat source. Moreover, the outer circumferential face of the coil 18 is cooled directly and the part to which the heat of the coil 18 is easily delivered, that is, a center pole 12 adjacent the inner outer circumferential face of the coil 18 and a top plate 16 and a bobbin 19 directly coupled with the coil 18 are cooled to reduce the temperature rise of the coil 18.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to all electrodynamic loudspeakers.

[0002]

2. Description of the Related Art In recent years, with the increase in output of audio amplifiers, it has been required that speakers used particularly for business use have high input resistance, can reproduce heavy bass, and have low distortion.

A conventional speaker will be described below with reference to the drawings. FIG. 7 shows a structural cross-sectional view of a conventional speaker. As components, 1 in the drawing is a center pole, 2 is a magnet that is joined to the lower surface of the center pole 1 and is magnetized in the thickness direction, 3 is an under plate that is joined to the lower surface of the magnet 2, and 4 is an under plate 3. A yoke joined to the outer peripheral portion, 5 is joined to the upper surface of the yoke 4, and an inner peripheral surface forms a magnetic gap with the outer peripheral surface of the center pole 1, 6 is a frame joined to the top plate 5, and 7 is A voice coil held in the magnetic gap and oscillating in response to an electric signal, 8 is a voice coil bobbin for transmitting the driving force generated in the voice coil 7 to the vibration system, 9 is a diaphragm bonded to the tip of the voice coil bobbin 8, 10
Is an air-permeable damper in which the inner peripheral portion is joined to the middle portion of the voice coil bobbin 8 and the outer peripheral portion is joined to the frame 6, and 11 is the inner peripheral portion joined to the outer peripheral portion of the diaphragm 9,
The outer peripheral portion is a roll-shaped edge joined to the frame 6.

In the conventional speaker having the above-described components, the space C formed by the upper surface of the center pole 1, the inner peripheral surface of the voice coil bobbin 8 and the lower surface of the diaphragm 9 is the outer peripheral surface of the center pole 1 and the voice coil bobbin. A space B formed by the outer peripheral surface of the center pole 1 and the magnet 2, the upper surface of the under plate 3, the inner peripheral surface of the yoke 4, and the lower surface of the top plate 5 via a slit formed in the inner peripheral surface of 8.
And the air gap between the outside of the frame, that is, the outside space of the speaker, through the slit formed by the inner peripheral surface of the top plate 5 and the outer peripheral surface of the voice coil 7 and the damper 10 having air permeability. Has been done.

[0005]

When a large input is applied to the speaker having the above structure, a large current flows through the voice coil 7 and the voice coil 7 generates heat. The heat generated in the voice coil 7 is transferred to the center pole 1 through the air in the space sandwiched between the outer peripheral surface of the center pole 1 and the inner peripheral surface of the voice coil bobbin 8, and the inner peripheral surface of the top plate 5 and the voice coil 7 is cooled by being transmitted to the top plate 5 through the air in the space sandwiched between the outer peripheral surfaces of the voice coil 7, and the air in the slit formed by the inner peripheral surface of the top plate 5 and the outer peripheral surface of the voice coil 7. It is also cooled by moving. However, air has a low thermal conductivity, and the ventilation between the space C and the external space of the speaker is caused by the gap between the outer peripheral surface of the center pole 1 and the inner peripheral surface of the voice coil bobbin 8 and the top plate 5.
Since it is made through the narrow gap between the inner peripheral surface of the voice coil 7 and the outer peripheral surface of the voice coil 7, the ventilation is insufficient and the heat of the voice coil 7 is not sufficiently cooled. As a result, the resistance value of the voice coil 7 increases due to heat generation, the current decreases, and the output sound pressure corresponding to the electric input cannot be obtained.

Further, during the operation of the speaker, the expansion / compression of the air in the space C is repeated. Especially, at the time of a large amplitude in the low tone range, the expansion / compression rate of the air becomes large due to insufficient ventilation, and the amplitude is suppressed and the reproduction is performed. Not only was the sound pressure level lowered, but distortion was caused by the non-linearity of air compliance.

It is an object of the present invention to provide a speaker with high input resistance and low distortion in which the temperature rise of the voice coil is reduced.

[0008]

In order to achieve the above object, the present invention provides a space formed by an upper surface of a magnetic circuit portion, an inner peripheral surface of a frame, a lower surface of a damper, and an outer peripheral surface of a voice coil bobbin, and a magnetic circuit. At least one ventilation passage is formed in the magnetic circuit portion between the outer space of the portion and the outer peripheral surface of the voice coil.

[0009]

With the above-described structure, the present invention cools the voice coil by the air flow that moves with the movement of the damper in the air passage that connects the inner and outer spaces of the speaker passing through the outer peripheral surface of the voice coil.

[0010]

1 is a structural sectional view of a speaker according to a first embodiment of the present invention and FIG. 2 is a perspective view of a magnetic circuit portion of the speaker. In the figure, 12 is a substantially columnar center pole, 13 is a disk-shaped magnet magnetized in the thickness direction, 14 is a disk-shaped underplate, 15 is a cylindrical yoke, and 16 is an annular shape. Top plate, 17 is a frame, 18 is a voice coil, 19 is a voice coil bobbin, 20 is a diaphragm, 21 is a highly airtight damper, 22
Is an edge, and the mutually assembled structure is similar to that of the above-mentioned conventional example. A feature of the present embodiment is that the first vent hole 23 is provided by removing a part of the inner peripheral surface of the top plate 16 and the second vent hole 24 is provided in the yoke 15.

The operation of the above configuration will be described. The air passage is formed by removing a part of the inner peripheral surface of the top plate 16 and the space A formed by the upper surface of the top plate 16, the inner peripheral surface of the frame 17, the outer peripheral surface of the voice coil bobbin 19, and the lower surface of the damper 21. A first ventilation hole 23 provided in the space, a space B formed by the outer peripheral surfaces of the center pole 12 and the magnet 13, the upper surface of the under plate 14, the inner peripheral surface of the yoke 15, and the lower surface of the top plate 16, and a yoke. It is formed between the 2nd ventilation hole 24 provided in 15 and the external space of a speaker. When the diaphragm 20 moves downward during operation, the air in the space A moves to the space B via the first ventilation hole 23 and further to the external space of the speaker via the second ventilation hole 24. Is discharged to. Conversely, when the diaphragm 20 moves upward, the air in the external space of the speaker moves to the space B via the second ventilation hole 24, and further to the space via the first ventilation hole 23. It flows into A. Therefore, the airflow passing through the first ventilation hole 23 directly cools the outer peripheral surface of the voice coil 18 as a heat source, and moreover, the heat of the voice coil 18 is easily transferred, that is, the inner and outer peripheral surfaces of the voice coil 18. Center pole 12 adjacent to
Since the top plate 16 and the voice coil bobbin 19 directly joined to the voice coil 18 are cooled, the temperature rise of the voice coil 18 is reduced.

Further, the first vent hole 23 and the second vent hole 24 have the same shape, and the top plate 16
And the yoke 15 are arranged at equal intervals, the voice coil 18, the voice coil bobbin 19 and the damper 21,
The radial pressures exerted by the air moving in the air passages cancel each other out, so that rolling due to the imbalance of the wind pressure from the air passages can be prevented.

In this embodiment, the second ventilation hole 24
Is provided on the yoke 15, but the under plate 14
The same effect can be obtained even if it is provided on both the under plate 14 and the yoke 15. Further, although the inner magnet type magnetic circuit is used, the same effect can be obtained even if the magnetic circuit is not limited to the inner magnet type, and for example, the outer magnet type is used.

Next, FIG. 3 and FIG. 4 respectively show a structural sectional view of a speaker of a second embodiment of the present invention and a perspective view of a magnetic circuit portion of the speaker. The reference numerals in the figure are exactly the same as those in the first embodiment. Here, what is largely different from the first embodiment is that the first ventilation hole 23 is expanded until the outer peripheral surface of the top plate 16 is removed and the second ventilation hole 24 is removed from the upper surface of the yoke 15. Provided, first
Two opposite inner peripheral surfaces of the vent hole 23 and the second vent hole 2
The two opposing inner peripheral surfaces of 4 are respectively located on the same plane to form one ventilation hole in which the first ventilation hole 23 and the second ventilation hole 24 are continuous, and further the frame 17 is formed. That is, the first vent hole 23 is provided in the joint portion with the top plate 16 while avoiding it. The operation of this embodiment is similar to that of the first embodiment, except that the first vent hole 2
When 3 is expanded and is continuous with the second ventilation hole 24, the ventilation path is enlarged at a portion passing through the outer peripheral surface of the voice coil 18. Therefore, even when the amount of air moving in the air passage increases when the amplitude is large, the air is easily vented, so that the distortion contained in the reproduced sound due to the compliance of the air in the air passage can be reduced.

In this embodiment, the second ventilation hole 24
Is provided only on the yoke 15, but the under plate 1
4 may also be provided. Next, FIG. 5 shows a structural cross-sectional view of the speaker of the third embodiment of the present invention. Here, 25 in the drawing is a third vent hole provided in the voice coil bobbin 19. The other reference numerals in the figure are exactly the same as those in the above embodiments.

Here, what is largely different from the above-described embodiments is that the damper 21 in the voice coil bobbin 19 is changed.
That is, the third vent hole 25 is provided between the joint portion of the diaphragm 20 and the joint portion of the diaphragm 20. The operation of this embodiment is similar to that of the previous embodiments, but by providing the third vent hole 25, the upper surface of the center pole 12, the inner peripheral surface of the voice coil bobbin 19, and the lower surface of the diaphragm 20 are provided. The third ventilation hole 2 is provided between the formed space C and the external space of the speaker.
Sufficient ventilation is possible via 5. Therefore, when the amplitude is large, the decrease in compliance and non-linearity caused by the expansion and compression of the air in the space C can be improved, so that the decrease in the output sound pressure level and the distortion in the reproduced sound can be reduced. Further, since the cooling effect of the upper surface of the center pole 12 and the inner peripheral surface of the voice coil bobbin 19 is increased, the temperature rise of the voice coil 18 can be further reduced.

Next, FIG. 6 shows a structural sectional view of a fourth embodiment of the present invention. The reference numerals in the figure are exactly the same as those in the third embodiment. Here, what is greatly different from the third embodiment is that the third vent hole 25 provided in the voice coil bobbin 19 is located between the joint portion with the damper 21 and the voice coil 18. . The operation of this embodiment is similar to that of the third embodiment, but the third vent hole 2
By providing 5 on the lower surface side of the damper 21, the space C and
Sufficient ventilation is possible with the space A. Therefore,
As a result of the space C becoming a part of the air passage that passes through the outer peripheral surface of the voice coil 18, the amount of air moving in the air passage increases with the same amplitude amount as compared with the previous embodiments, and the voice Since the cooling effect of the coil 18, the center pole 12, the top plate 16, and the voice coil bobbin 19 is increased, the temperature rise of the voice coil 18 is further reduced.

[0018]

As is apparent from the above description of the embodiments, the present invention provides a speaker with high input resistance and low distortion, in which the airflow generated with the vibration of the damper having enhanced airtightness is magnetic. Since the outer peripheral surface of the voice coil is directly air-cooled by passing through the ventilation passage provided in the circuit portion, it is possible to reduce the temperature rise of the voice coil at the time of a large input.

[Brief description of drawings]

FIG. 1 is a sectional view of a speaker according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a magnetic circuit section of the speaker.

FIG. 3 is a sectional view of a speaker according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a magnetic circuit unit of the speaker.

FIG. 5 is a sectional view of a speaker according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a speaker according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view of a conventional speaker.

[Explanation of symbols]

 12 center pole 13 magnet 14 under plate 15 yoke 16 top plate 17 frame 18 voice coil 19 voice coil bobbin 20 diaphragm 21 damper 22 edge 23 first ventilation hole 24 second ventilation hole 25 third ventilation hole

Claims (8)

[Claims] 1. A magnetic circuit unit, a frame joined to the magnetic circuit unit, a voice coil held in a magnetic gap of the magnetic circuit unit, a voice coil bobbin joined to the voice coil, and the voice. A diaphragm joined to the upper end of the coil bobbin, a damper having inner and outer peripheral portions joined to the voice coil bobbin and the middle part of the frame and having airtightness, and inner and outer portions to the outer peripheral part of the diaphragm and the upper end of the frame, respectively. A space surrounded by an upper surface of the magnetic circuit portion, an inner peripheral surface of the frame, an outer peripheral surface of the voice coil bobbin, and a lower surface of the damper; and an outer portion of the magnetic circuit. At least one air passage is formed in the magnetic circuit portion between the space and a part of the inner peripheral surface of the air passage is outside the voice coil. A speaker characterized by being formed on a peripheral surface. 2. The magnetic circuit portion includes a substantially columnar center pole, a disc-shaped magnet joined to a lower surface of the center pole, and a disc-shaped under plate joined to a lower surface of the magnet. It is composed of a cylindrical yoke joined to the outer peripheral portion of the under plate, and an annular top plate joined to the upper surface of the yoke, the magnet is magnetized in the thickness direction, and the magnetic gap of the center pole is The air passage is formed by an outer peripheral surface and an inner peripheral surface of the top plate, and a ventilation path is surrounded by an upper surface of the top plate, an inner peripheral surface of the frame, an outer peripheral surface of the voice coil bobbin, and a lower surface of the damper, and the center pole. And a space surrounded by the outer peripheral surface of the magnet, the upper surface of the under plate, the inner peripheral surface of the yoke and the lower surface of the top plate, and the outside of the magnetic circuit. A first vent hole formed in the top plate by removing a part of an inner peripheral surface of the top plate between the partial space and a second hole formed in at least one of the under plate and the yoke; The speaker according to claim 1, wherein the speaker has a ventilation hole. 3. The speaker according to claim 2, wherein a plurality of first ventilation holes are provided, all of them have the same shape, and are arranged at equal intervals on the inner peripheral surface of the top plate. 4. A plurality of second vent holes are provided, all of which have the same shape, and are located at equal intervals on a concentric circle of the under plate or on a circumference of the yoke at the same height. The speaker according to claim 2. 5. The first ventilation hole is expanded until the outer peripheral surface of the top plate is removed, and the second ventilation hole is provided at a position where the upper surface of the yoke is removed so that the first ventilation hole faces the first ventilation hole. Two inner peripheral surfaces facing each other and two of the second ventilation holes facing each other.
The speaker according to claim 2, wherein the inner peripheral surfaces are located substantially on the same plane. 6. The speaker according to claim 1, wherein the voice coil bobbin is provided with at least one third vent hole. 7. The speaker according to claim 6, wherein the third ventilation hole is located between a joint portion between the voice coil bobbin and the damper and the diaphragm. 8. The speaker according to claim 6, wherein the third ventilation hole is located between the voice coil and the joint between the voice coil bobbin and the damper.