JPH0430800B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic circuit for an external magnetic speaker.

Conventional configurations and their problems In recent years, many flat-plate speakers have been put into practical use. In such flat-plate speakers, the diaphragm uses regions that do not resonate separately, so it is difficult to reproduce an audible frequency band with a single flat-plate speaker. Alternatively, an audible frequency band is reproduced using a coaxial composite speaker that includes a plurality of speaker units concentrically arranged.

A conventional coaxial type composite speaker using a magnetic circuit will be explained with reference to FIGS. 1 and 2. 1st
As shown in the figure, an annular magnet 2 is bonded to a center pole 1, and a plate 3 is placed on top of the annular magnet 2 to form a magnetic circuit. This magnetic circuit is used in a treble speaker (hereinafter referred to as a tweeter) and is combined with a bass speaker (hereinafter referred to as a woofer) to form a coaxial two-way speaker, as shown in FIG. A holding stand 5 for the tweeter is attached to the magnetic circuit 4 for the woofer.
A tweeter is configured in the center via. 6
is a tweeter diaphragm, and its outer peripheral portion is fixed to a tweeter frame 8 via an edge 7. A woofer inner edge 9 having a semicircular cross section is fixed to the outer circumference of the tweeter frame 8, and the inner edge 9 holds a woofer diaphragm 12 together with an outer edge 10 and a damper 11. The outer diameter of the tweeter frame 8 is configured to be approximately equal to the outer diameter of the annular magnet 2 of the tweeter. this is,
This is to prevent the inner peripheral edge 9 from coming into contact with the tweeter frame 8 due to the vibration of the woofer diaphragm 12.

However, in the above-described conventional configuration, the woofer diaphragm 12 is affected by the size of the tweeter's magnetic circuit, and as the tweeter's annular magnet 2 becomes larger, the area of the woofer diaphragm 12 decreases and the sound pressure decreases. Conversely, if the woofer diaphragm 12 was to be made larger, the tweeter's magnetic circuit would have to be made smaller, resulting in a problem in that the tweeter's sound pressure would drop.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and provides a magnetic circuit for a speaker, which is a magnetic circuit used in a tweeter and can increase the area of a diaphragm of a woofer without reducing the sound pressure of the tweeter. With the goal.

Structure of the Invention In order to achieve the above object, a magnetic circuit for a speaker according to the present invention includes a center pole, a plate forming a magnetic gap between the center pole and the center pole, one end surface of which is in contact with the center pole, and the other end surface of which is in contact with the center pole. A treble speaker consisting of a treble magnetic circuit made up of a magnet in contact with the plate is placed in the center, and a bass speaker is further held on the outer periphery of the treble speaker via an edge so that it can vibrate. A bass magnetic circuit comprising a diaphragm and constituting a bass speaker is arranged, and the outer peripheral surface of the magnet of the treble magnetic circuit is gradually or continuously reduced in diameter from the one end surface side to the other end surface side. , a vibration space for the edge is formed on the outer periphery of the other end surface of the magnet.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Fig. 3 is a sectional view of a magnetic circuit, and Fig. 4 is a sectional view of a coaxial composite speaker using the magnetic circuit shown in Fig. 3. Reference numerals are given and explanations thereof are omitted.

3 and 4, reference numeral 13 denotes an annular magnet, and this annular magnet has a stepped portion formed in the center of the outer peripheral surface in the axial direction, and the contact surface side with the bottom of the center pole 1 is closer to the plate. It is configured to have a larger diameter than the contact surface side with 3.

According to the conventional structure, as shown in FIG. 5, the inner edge 9 of the woofer is placed inside the outer circumference of the annular magnet 2 for the tweeter in order to prevent contact with the tweeter frame 8 due to vibration. Unable to position edge 9. However, in the magnetic circuit of this embodiment, the annular magnet 1 has a smaller outer diameter on the plate 3 side than the outer diameter on the bottom side of the center pole 1.
3, a space can be formed above the large diameter portion of the annular magnet 13, and the inner peripheral edge 9 of the woofer can be bonded further inside. Even when the woofer diaphragm 12 vibrates as shown by the imaginary line in FIG. 6, the inner edge 9 does not come into contact with the tweeter frame 8. Therefore, the inner diameter of the woofer diaphragm 12 can be reduced from _r0 to r,
The area of the woofer diaphragm 12 can be increased.
Furthermore, as shown in FIG. 7, when a woofer diaphragm 12 with a conventional configuration and an inner diameter r similar to that of this embodiment is used, the annular magnet 2 has a small diameter, and the magnetic flux density of the tweeter magnetic circuit is reduced. However, in this embodiment, such a situation does not occur.

To give a specific example, in a composite speaker using a 20 cm diameter woofer and a 2.8 cm tweeter, in the conventional configuration, the outer diameter of the annular magnet 2 of the tweeter
60mm, inner diameter 26mm, height 13mm, center pole 1 diameter 19mm, inner edge 9 width 11mm, woofer diaphragm 12 inner diameter 86mm, and the magnetic flux density of the tweeter's magnetic circuit was 15000 Gauss. . On the other hand, in the magnetic circuit of this embodiment, when the large diameter part of the annular magnet 13 has an outer diameter of 60 mm and a height of 9 mm, and the upper half has an outer diameter of 50 mm, a height of 4 mm, and an inner diameter of 26 mm, the inner diameter of the woofer diaphragm 12 was able to be reduced to 76mm. At this time, the tweeter's magnetic flux density was 14,700 Gauss and hardly decreased.

Further, as shown in Fig. 7, when a woofer diaphragm 12 with an inner diameter of 76 mm is combined with a conventional magnetic circuit, the annular magnet 2 of the tweeter's magnetic circuit has an outer diameter of 50 mm.
mm, inner diameter 26mm, height 13mm, magnetic flux density is
It dropped significantly to 13,200 Gauss.

When the outer diameter of the woofer diaphragm 12 is 155 mm, the magnetic circuit according to this embodiment increases the area of the woofer diaphragm 12 by about 10%, and the tweeter magnetic flux density decreases by 12% in the conventional configuration. In contrast, we were able to create an excellent speaker with a reduction of only 2%.

8 and 9 show another embodiment,
As shown in FIG. 8, an annular magnet 14 whose outer diameter increases in multiple steps from the plate 3 side to the bottom side of the center pole 1 may be used, and as shown in FIG. An annular magnet 15 whose outer diameter increases continuously toward the bottom side may also be used.

Effects of the Invention As explained above, according to the present invention, in the coaxial composite speaker, the outer diameter of the annular magnet of the high-pitched magnetic circuit is made smaller on the other end side than on the one end side. An edge vibration space for holding the bass diaphragm can be created near the other end surface around the annular magnet without reducing the magnetic flux density of the treble magnetic circuit, and this can be used as the tweeter magnetic circuit to create a coaxial composite speaker. With this configuration, the vibration area of the woofer can be increased and the sound pressure can be increased.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional magnetic circuit, FIG. 2 is a sectional view of a coaxial composite speaker using a conventional magnetic circuit, FIG. 3 is a sectional view of a magnetic circuit in an embodiment of the present invention, and FIG. The figure is a sectional view of a coaxial type composite speaker using the same magnetic circuit, and Figures 5 to 7 are a coaxial type composite speaker using a conventional magnetic circuit and a coaxial type composite speaker using a magnetic circuit according to an embodiment of the present invention. The operation explanatory diagrams of the composite speaker, FIGS. 8 and 9, are sectional views of magnetic circuits in different embodiments. 1... Center pole, 3... Plate, 9...
...Edge, 12...Diaphragm for woofer, 13,1
4,15...Annular magnet.

Claims (1)

[Claims] 1 Consists of a high-pitched magnetic circuit consisting of a center pole, a plate that forms a magnetic gap between the center pole, and a magnet whose one end surface abuts the center pole and the other end abuts the plate. A treble speaker is arranged in the center, and a bass magnetic circuit is arranged on the outer periphery of the treble speaker to form a bass speaker, including a bass diaphragm that is held vibratingly through edges. For a speaker, the diameter of the outer circumferential surface of the magnet of the magnetic circuit for high-pitched sounds is gradually or continuously reduced in diameter from the one end surface side to the other end surface side, and the vibration space of the edge is formed on the outer circumferential portion of the other end surface side of the magnet. magnetic circuit.