The present invention relates to a loudspeaker for use in car-borne audio equipment and the like.
A conventional loudspeaker is described referring to
The magnetic circuit A is fixed to the frame 6 by inserting a plurality of protrusions 4a provided at the outer edge of yoke 4 into a plurality of fixing holes 6a provided in the frame 6, and caulking, or swaging, them.
Many of the recent car-borne audio equipment are also boasting of a greater output in their compact overall dimensions. With an aim to make the magnetic circuit A of a speaker small and compact, a magnet of neodymium, which has a higher magnetic energy as compared with conventional ferrite magnets, is increasingly used for the magnet 1. This requires subtle work during assembly of a loudspeaker in connecting the magnetic circuit A with the frame 6.
A loudspeaker of the present invention comprises a magnetic circuit, a plastic frame to be connected with the magnetic circuit, a voice coil disposed in a magnetic gap of the magnetic circuit, and a diaphragm coupled to the voice coil. In the loudspeaker, the frame and the magnetic circuit are connected together by means of an elastic fastener provided on the frame.
In an example of a loudspeaker in accordance with an exemplary embodiment of the present invention, the frame and yoke are connected together by fitting a plurality of elastic fasteners provided on a circle of a bottom surface of the frame to the yoke.
In another exemplary embodiment of the present invention, the elastic fastener is a clip provided on a circle of the bottom of the frame. The frame and the magnetic circuit are connected together by means of the clips and expansions provided along the outer circumference of the magnetic circuit.
A loudspeaker in accordance an exemplary embodiment of the present invention is described in the following with reference to
A loudspeaker in a first exemplary embodiment of the present invention is described with reference to
The loudspeaker of the present embodiment comprises a voice coil 14 having an air ventilation hole 14a, a plastic frame 11, a plurality of elastic fasteners 11a provided at the vicinity of an inner circumference of the frame 11, an outer cylindrical portion 12a of a yoke 12, the outer cylindrical portion 12a designed to engage at its outer circumference with the elastic fastener 11a, and a bottom portion 12b connected at its outer circumference with the outer cylindrical portion 12a. In addition, a single elastic fastener 11a could be used. The yoke 12 comprises the outer cylindrical portion 12a and the bottom portion 12b. Thus, the loudspeaker of the present embodiment has an inner magnet type magnetic circuit.
In a loudspeaker of the present embodiment configured as above, the frame 11 and the yoke 12 are fastened together through a snap-in action, by deforming the elastic fastener 11a with the outer circumference of the yoke 12, as illustrated in
A firm and rigid bonding can be established if an adhesive material is applied around the outer circumference of the yoke 12 and the inner circumference of the frame 11.
In the above case, the elastic fastener 11a works also as a temporary holding member, and the assembly operation for a loudspeaker unit can proceed without needing any consideration of the time required for the adhesive material to hardened.
Furthermore, since the yoke 12 of the loudspeaker in the present embodiment is formed of a component split into two units, there is no need for deep-drawing work of a metal sheet when manufacturing the yoke 12. This contributes to an improved productivity during the production of the yoke 12.
Even in a case where the frame 11 is manufactured with a material other than plastic material, a similar advantage of an improved productivity can be obtained by providing a yoke 12 alone with the configuration in which the component is split into two units. In this case, the yoke 12 is provided at the outer circumference edge with a caulking portion 12c as shown in
Next, a structure of the yoke 12, where the component has been split into two units for forming the yoke, is described more in detail.
Since the cross sectional form of the yoke is as illustrated in
In the present embodiment, the outer cylindrical portion 12a is provided with a step 12c at the bottom end, and the bottom 12b is provided with a tapered portion 12e at the edge of the outer circumference, as shown in
The yoke 12 is assembled into one component by fitting the circumference edge of the disk-shaped bottom 12b, which has a lift-up portion in the center, to the step 12c, and fixing the bottom 12b by surrounding it with an edge of the bottom rim 12d of the outer cylindrical portion 12a by a caulking process.
The caulking of the bottom rim 12d of the outer cylindrical portion is conducted along the contour of the tapered portion 12e. Therefore, the caulking can be performed easily in a reliable manner. Furthermore, edge of the bottom rim 12d is not folded as far as a right angle in the caulking operation, which contributes to prevent deterioration in the caulking strength.
Referring to
A groove 15 provided along the outer circumference of the top plate 2 and the yoke bottom 12b is a reservoir for preventing an adhesive material for bonding the top plate 2, the yoke bottom 12b and the magnet 1 from squeezing out to the side face.
A loudspeaker of the present embodiment is provided with an air ventilation hole 14a in the voice coil 14. Air within the voice coil 14 can move to a space 8b formed by a damper 8 when the air is compressed as a result of a movement of the voice coil 14. This reduces a resistance of airflow, and contributes to improve the response characteristic of a loudspeaker during reproduction of low frequency range sounds, when the amplitude becomes great. This also prevents the heat generated at voice coil 14 from staying within the voice coil 14. When the air ventilation hole 14a is disposed at a certain specific location so that it is concealed inside the magnetic gap at a time of great amplitude with the voice coil 14, the airflow resistance at that stage gets a sudden increase. Such a configuration can be used as an air brake for preventing the voice coil 14 from colliding with the yoke bottom 12b.
A loudspeaker in accordance with a second exemplary embodiment of the present invention is described with reference to
As shown in
The above-configured yoke 20 and frame 21 are disposed so that the cuts 20a are placed to be fitted to a location corresponding to the clip sections 21a, and then the yoke 20 is revolved so that expansions 20b are under the clip sections 21a, as shown in
As shown in
Although the number of cuts 20a and the corresponding clip sections 21a has been described to be three in the above descriptions, the number is not limited to three. These elements may be provided in an appropriate number, depending on the overall shape and the dimensions of loudspeakers.
In order to provide improved heat radiation, such schemes as shown in
In the descriptions of the above embodiments of the present invention, a loudspeaker having an inner magnetic type magnetic circuit has mostly been used as an example, where an expensive neodymium magnet is used. The present invention, however, is also applicable to a loudspeaker having an outer magnet type magnetic circuit, by replacing a yoke in the above description with a top plate of an outer magnet type magnetic circuit.
As described above, a frame and a yoke can be easily connected together in a loudspeaker of the present invention, despite the compact and small magnetic circuit thereof. Thus, the present invention brings about a significant advantage in the industry.
Number | Name | Date | Kind |
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2295483 | Knowles | Sep 1942 | A |
3176086 | Coen | Mar 1965 | A |
3991286 | Henricksen | Nov 1976 | A |
5111510 | Mitobe | May 1992 | A |
5940522 | Cahill et al. | Aug 1999 | A |
6373957 | Stewart | Apr 2002 | B1 |
Number | Date | Country |
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0121613 | Oct 1978 | JP |
Number | Date | Country | |
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20020044671 A1 | Apr 2002 | US |