JPH089494A - Magnetic circuit for speaker - Google Patents

Abstract

PURPOSE:To reduce temperature rise in the magnetic circuit and in a voice coil by providing a connection part which connects the outer and inner peripheral sides of the magnet and circulating the outside air in the half-closed magnetic circuit. CONSTITUTION:A magnetic circuit A comprises a field magnetic circuit by a plate 1, a magnet 2, a bottom plate 3, and a center pole 4. In the circuit A, a connection part 11 is provided to connect the outside and inner peripheral sides of the magnet 2. As a means to form the connection part 11, a through hole 12 is provided in the direction of the inside surface 2b from the outside surface 2a of the ring-shaped magnet 2. Several through holes 12 which extend radially from the center are set. The through holes 12 can be arranged in parallel. When the outside air is forcedly sent from the outside in the magnetic circuit for cooling, the influence of the air pressure given to the vibration system can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic circuit for a speaker, and more particularly to an external magnet type magnetic circuit having a heat radiation effect.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional general loudspeaker uses an outer magnet type magnetic circuit composed of a top plate 1, a magnet 2, a bottom plate 3 and a center pole 4. There is. In the figure, 5
Is a voice coil, 6 is a diaphragm, 7 is a damper, 8 is a frame, and 9 is a dust cap for preventing dust from entering the magnetic circuit.

In the above magnetic circuit, the inside 10 of the magnetic circuit constitutes a semi-enclosed space, and the heat generated during voice reproduction is radiated from the magnetic gap G or constitutes the magnetic circuit. Heat was transferred to each member and was radiated.
Further, there is also one in which a through hole 4a is provided at the center of the center pole 4 in order to enhance the heat dissipation from the magnetic gap G.

[0004]

In the conventional external magnet type magnetic circuit, the fluidity of the stagnant air is poor, which is a background to the thermal limit of the voice coil 5. Further, in the case where the center pole 4 is provided with the through hole 4a, when a cooling method for forcibly inflowing the outside air from the outside is adopted,
The pressure of the inflowing outside air was added to the vibration system, which interfered with the sound reproduction. Further, in such a structure, when the speaker is mounted as a vehicle-mounted speaker and is installed upright on a door of a car or the like, the through hole 4a becomes horizontal, which causes water to flow into the magnetic circuit and causes the moisture to flow into the magnetic circuit. Since the inflowing water remains without being discharged, rust is generated on each member, which is also a factor causing defective reproduction such as burr and kosle.

An object of the present invention is to reduce the temperature rise of the magnetic circuit and the voice coil and improve the input withstand characteristics.
It is an object of the present invention to provide a magnetic circuit for a speaker that can easily discharge water that has entered the inside of the magnetic circuit when used for a vehicle-mounted speaker.

[0006]

The speaker magnetic circuit of the present invention is an external magnet type magnetic circuit provided with a communicating portion for communicating the outer peripheral side and the inner peripheral side of the magnet.

A plurality of communicating portions are provided, and as a means for forming the communicating portions, a through hole penetrating from the outer peripheral surface to the inner peripheral surface of the magnet is provided, or the magnet is constructed by stacking two magnets and both magnets are formed. A ring-shaped spacer made of a magnetic material and having a through hole or a communication groove extending from the outer peripheral surface to the inner peripheral surface may be sandwiched between the two. Alternatively, a groove may be formed on the upper surface of the bottom plate and the magnet may be arranged so as to cover the groove.

[0008]

In the external magnet type magnetic circuit for the speaker, the external air is circulated in the semi-hermetically closed magnetic circuit by providing the communicating portion for connecting the outer peripheral side and the inner peripheral side of the magnet. As a result, the temperature rise of the magnetic circuit and voice coil is reduced, and the input withstand characteristics are improved.

Further, in the case where the outside air is forcedly flowed in through the communication hole to perform forced cooling, the effect of air pressure exerted on the vibration system can be reduced by providing a plurality of communication holes. Furthermore, when it is used as a magnetic circuit for an on-vehicle speaker, water that has entered the magnetic circuit can be discharged through the through holes, and rust may be generated on each member such as the plate, magnet, bottom plate, and center pole. It is possible to reduce the number of defects, and it is possible to reduce defective reproduction due to burrs, scratches and the like.

[0010]

FIG. 1 shows an embodiment of a magnetic circuit for a speaker according to the present invention.
4 will be described with reference to FIG. 4, the same parts as those of the conventional one described with reference to FIG. 5 will be assigned the same reference numerals and detailed description thereof will be omitted. FIG. 1 is a cross-sectional view showing a state in which the magnetic circuit A is incorporated in a cone type speaker.
Magnet 2, bottom plate 3 and center pole 4
An outer magnet type magnetic circuit is constituted by the above. The magnetic circuit A is provided with a communicating portion 11 for communicating the outer peripheral side and the inner peripheral side of the magnet 2.

As a means for forming the communicating portion 11, in the example of FIG. 1, a through hole 12 is provided from the outer surface 2a of the ring-shaped magnet 2 toward the inner surface 2b. A plurality of the through holes 12 are provided, and in the example of FIG. 2A, they are provided radially from the center side. Further, in the example of FIG. 2B, the through holes 12 are provided in a flat shape, and in this application example, when the external air is forcibly fed into the magnetic circuit from the outside for cooling, the vibration system is not used. It is possible to reduce the influence of air pressure exerted.

In FIG. 3, as another means for providing the communicating portion 11, in order to facilitate the production, the magnet 2 is constructed by stacking the upper and lower magnets 2A and 2B in two stages, and between the magnets 2A and 2B. In this example, a ring-shaped spacer 13 made of a magnetic material having a through hole 14 penetrating from the outer peripheral surface to the inner peripheral surface is sandwiched. Also, the through hole 14
Instead of the above, a communication groove extending from the outer peripheral surface to the inner peripheral surface is provided on one side of the spacer 13, and the magnet 2 is covered so as to cover the communication groove.
May be arranged to form the communication part. FIG. 4 shows another form in which the number of parts is reduced and the communicating portion 11 is simply provided. An example in which a groove 3a is formed on the upper surface of the bottom plate 3 and the magnet 2 is arranged so as to cover the groove 3a. Is.

[0013]

According to the magnetic circuit for a speaker of the present invention,
By providing a communication part for communicating the outer circumference side and the inner circumference side of the magnet, the outside air is circulated inside the magnetic circuit in the semi-sealed state, and the temperature rise of the magnetic circuit and the voice coil is reduced. Therefore, the input withstand characteristic is improved.

Further, when the outside air is forced to flow through the communication hole for forced cooling, the effect of air pressure on the vibration system can be reduced by providing a plurality of communication holes, and further, the magnetic force of the vehicle-mounted speaker can be reduced. When used as a circuit, water that has entered the inside of the magnetic circuit can flow out through the through holes, and it is possible to reduce the generation of rust on each member such as the plate, magnet, bottom plate, center pole, etc. It is possible to reduce defective reproduction due to the above.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a speaker magnetic circuit of the present invention is incorporated in a speaker.

FIG. 2 shows a form of a through hole formed in a magnet,
FIG. 7A is a plan view of an example of radial formation, and FIG. 9B is a plan view of an example of parallel formation.

FIG. 3 is a cross-sectional view showing an example of using a ring-shaped spacer made of a magnetic material to form a communication hole.

FIG. 4 is a sectional view showing an example in which a groove is formed in a bottom plate to form a communication hole.

FIG. 5 is a cross-sectional view showing a conventional speaker magnetic circuit.

[Explanation of symbols]

 A magnetic circuit 1 top plate 2 magnet 2a upper magnet 2B lower magnet 3 bottom plate 3a groove 4 center pole 5 voice coil 6 diaphragm 7 damper 8 frame 9 dust cap G magnetic gap 11 communication part 12 through hole 13 with through hole 14 Spacer

Claims (6)

[Claims] 1. A magnetic circuit for a speaker, characterized in that, in an outer magnet type magnetic circuit, a communicating portion is provided for communicating the outer peripheral side and the inner peripheral side of the magnet. 2. The magnetic circuit for a speaker according to claim 1, wherein a plurality of communicating portions are provided. 3. The speaker magnetic circuit according to claim 1, wherein the communication portion is a through hole penetrating from the outer peripheral surface of the magnet to the inner peripheral surface thereof. 4. A ring-shaped spacer made of a magnetic material is sandwiched and arranged between magnets formed by stacking two stages, and a through hole or a communication groove reaching from the outer peripheral surface to the inner peripheral surface is formed in the spacer. The magnetic circuit for a speaker according to claim 1, wherein the communication portion is formed by. 5. The communication part is formed by forming a groove on the upper surface of the bottom plate and arranging a magnet so as to cover the groove to form a communication portion.
A magnetic circuit for a speaker as described. 6. The outer magnet type magnetic circuit is characterized in that a vertical groove is formed on the outer peripheral surface of the center pole and a communication portion for connecting the outer peripheral side and the inner peripheral side of the magnet is provided. Magnetic circuit for speaker.