JPS6113679B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides electrical equipment such as speakers, microphones, etc.
The purpose of this invention is to improve the input resistance of acoustic transducers.

As a conventional example, a cone-type dynamic speaker is shown in FIG. In the speaker shown in FIG. 1, a magnet 2 is fixed to a yoke 1a of a center pole 1 made of a magnetic material, and a ring-shaped plate 3 made of a magnetic material is attached to the magnet 2 so that its inner circumference is the outer circumference of the center pole 1. It is fixed so that it has a constant magnetic gap with the surface. The voice coil 4 is wound around a voice coil bobbin 5 so as not to contact either the center pole 1 or the plate 3, and is located in the magnetic gap. A diaphragm 6 is attached to one end of the voice coil bobbin 5, and the diaphragm 6, voice coil bobbin 5, and voice coil 4 are driven together. Note that these integrally driven members are collectively referred to as a vibration system. This vibration system includes a frame 9 fixed to the plate 3 with screws 10, a damper 7 made of a viscoelastic material,
It is supported via an edge 8 so as to be movable in the direction of the central axis of the center pole 1 . As is clear from FIG. 1, the voice coil 4 is surrounded by air with poor thermal conductivity. Therefore, when a large current flows through the voice coil 4, the voice coil 4 generates heat, and when subjected to a large current for a long time, it is overheated, the voice coil bobbin 5 and the voice coil 4 are deformed, and the plate 2
leading to contact with. Also, voice coil 4 due to overheating.
There is a risk that the voice coil 4 and the voice coil bobbin 5 will separate as the adhesion deteriorates. This drawback is not limited to the above-mentioned cone type dynamic speakers.
This also occurs with dome speakers and dynamic microphones.

The present invention has been devised to address this problem, and aims to provide an electro-acoustic transducer that cools the voice coil and improves input resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to drawings showing embodiments using a cone-type dynamic speaker as an example. In the figure, the same reference numerals as in FIG. 1 indicate the same members, and detailed explanation thereof will be omitted. First, the first embodiment will be explained based on FIG. 2 showing the first embodiment. In the figure, reference numeral 11 is located at the middle part in the longitudinal direction inside the voice coil bobbin 5, and the inner peripheral edge is fixed to the tip of the center pole 1 by a screw 12, and the outer peripheral edge is close to the inner surface of the voice coil bobbin 5. An annular yoke member 14 is sealed with a magnetic liquid 13 between the center pole 1 and the inner circumferential edge thereof is fixed to the outer surface of the center pole 1 by soldering or the like. An annular yoke member whose peripheral edge is close to the inner surface of one end of the voice coil bobbin 5 and sealed with a magnetic liquid 13 between the voice coil bobbin 5 and the inner peripheral edge thereof is close to the outer surface of the intermediate portion in the length direction of the voice coil bobbin 5. A yoke member 16 has a magnetic liquid 13 sealed between it and the voice coil bobbin 5 facing the yoke member 11, and whose outer peripheral edge is fixed to one side of the plate 3 with a screw 12; close to the inner surface of one end of the coil bobbin 5 and the yoke member 1
It is a yoke member that faces the voice coil bobbin 4 and is sealed with a magnetic liquid 13, and whose outer peripheral edge is fixed to the other side of the plate 3 with screws 12. Each of these yoke members 11, 14, 15, 16
are all made of magnetic material, and a cooling fluid 18 is inside and outside two spaces 17a and 17b formed by the yoke members 11, 14, 15, and 16, the center pole 1, the voice coil bobbin 5, and the plate 3. Filled. Note that the voice coil 4 wound on the voice coil bobbin 5 is located in the outer space 1.
7b without contacting the yoke members 15, 16. Further, as the magnetic liquid 13, a material that does not mix with the cooling fluid 18 is used, for example, iron powder dispersed in oil is used, and the magnetic liquid 1 facing the voice coil bobbin 5 is
3 and 13 attract each other and the voice coil bobbin 5 can be sealed in a movable state. The other configurations are the same as those shown in FIG. Therefore, by configuring the magnetic liquid 13 as described above, the cooling fluid 18 is sealed regardless of the movement of the voice coil bobbin 5. Therefore, the voice coil 4 is driven in the fluid 18 in the sealed spaces 17a and 17b, and is cooled by the fluid 18 against heat generation at the time of large input. Also fluid 1
8 itself generates convection, and the cooling effect is maintained.

Next, a description will be given based on FIG. 3 showing a second embodiment.

In this embodiment, in addition to the first embodiment, a plurality of holes 19 and 20 are provided in the center pole 1 and the plate 3 in the spaces 17a and 17b, respectively, and the fluid 18 is caused to convect through the holes 19 and 20. The cooling effect is the first.
This is an improvement over the example.

Further, a description will be given based on FIG. 4 showing a third embodiment.

In this embodiment, in addition to the first embodiment, a plurality of slits 21 and 22 are provided in the outer periphery of the center pole 1 and the inner periphery of the plate 3 in the spaces 17a and 17b, respectively, and the fluid 18 is Convection is caused through the slits 21 and 22, and the cooling effect is improved compared to the first embodiment.

The present invention can be implemented as described above, and the heat generated by the voice coil is cooled by the filled fluid, and the effect continues due to the convection of the fluid itself. Furthermore, by making the cooling fluid have viscoelasticity, the resonance of the voice coil bobbin can also be dubbed. Therefore, according to the present invention, it is possible to provide an electro-acoustic transducer with improved input resistance and high efficiency.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional example, Figures 2 to 4
The figures are cross-sectional views showing different embodiments of the present invention. 1...Center pole, 1a...Yoke, 2...
... Magnet, 3 ... Plate, 4 ... Voice coil, 5 ... Voice coil bobbin, 6 ... Diaphragm, 9 ... Frame, 11 ... Yoke member, 12
...Bis, 13...Magnetic liquid, 14,15,16...
...Yoke member, 17a, 17b...Space, 18...
...Cooling fluid, 19, 20... Holes, 21, 22...
...Slit.

Claims (1)

[Scope of Claims] 1 Consists of a cylindrical center pole made of a magnetic material at the center and a magnetic material arranged so that the inner peripheral surface is located at a position with a certain magnetic gap from the outer peripheral surface of the center pole. a ring-shaped plate, a magnet magnetically coupled to the center pole and the plate, a frame that supports a diaphragm so as to be movable in the direction of the center axis of the center pole, and a voice coil bobbin connected to the diaphragm. , a voice coil wound around the peripheral surface of the voice coil bobbin and positioned so as to be movable in the longitudinal direction in the magnetic gap, the electro-acoustic transducer comprising:
each made of a magnetic body fixed to the center pole and the plate, and arranged on the voice coil bobbin circumferential surface facing the entire circumference and with a constant gap so as to form a space encompassing the entire voice coil; a pair of first yoke members and a second yoke member; a magnetic fluid attached to a predetermined gap between the first yoke member and the voice coil bobbin; and a pair of the second yoke member and the voice coil pin; 1st, 2nd
An electro-acoustic transducer, characterized in that the space including the voice coil, which is sealed by the yoke member and the magnetic fluid, is filled with a cooling fluid that does not mix with the magnetic fluid. 2. A space containing a voice coil sealed by the first and second yoke members and a magnetic fluid and filled with a cooling fluid, and a path through which the cooling fluid can flow is provided in the plate and center pole. An electro-acoustic transducer according to claim 1. 3. The electro-acoustic transducer according to claim 2, wherein the plate and center pole are provided with holes through which a cooling fluid can flow. 4. The electro-acoustic transducer according to claim 2, wherein the plate and center pole are provided with slits through which cooling fluid can flow.