JPS6157199A - Anti-magnetic device of speaker - Google Patents

Abstract

PURPOSE:To obtain remarkably efficient anti-magnetic device of a speaker cheaply y providing a back chamber for making a back cavity behind a speaker and constituting the back chaber by a magnetic material. CONSTITUTION:A general speaker is composed of a bottom plate 1, a magnet 2... a dust cap 11 or the like. Similarly to the conventional speaker, a leakage of magnetic flux (b) is generated from a magnetic circuit 4. But by providing the back chamber 16 composed of magnetic material, the magnetic flux (b) flows through the back chamber 16. Therefore the outside magmetic flux of the back chamber becomes extremely small. In this manner, by constituting the back chamber 16 for forming a back cavity with magnetic material, even in the conventional speaker, the leakage of the magnetic flux can be decreased and the anti-magnetic device eliminating te influence to the screen of a television can be realized inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic shielding device for a speaker that reduces magnetic flux leakage from the speaker.

Conventional configuration and its problems In recent years, the audio industry has been merging with visual equipment.

We are now moving into the so-called AV era, and there are many speaker systems on the market with magnetic shielding devices that do not cause color shift on the TV screen even when placed next to the TV. are awaited.

A conventional magnetic shielding device for a speaker will be explained below.
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FIG. 1 is a sectional view of a general speaker without a magnetic shield device. 1 is a bottom plate, 2 is a magnet glued thereon, 3 is a top plate glued on top of the magnet 2, 4 is a magnetic circuit constituted by the above three parts, 5 is a frame fixed to the top plate 3, 6
is a gasket, 7 is an edge with one end glued to the frame 5, 8 is a diaphragm supported by the edge 7, 9 is a voice coil, 1o is a damper that supports the voice coil, 1
1 is a dust cap adhered to the center of the diaphragm 8.

In the general subica constructed as described above, since the magnetic circuit 4 has a so-called external magnetic type configuration, leakage magnetic flux 1 between the top plate 3 and the bottom plate 1 is unavoidable. , which has quite a negative effect on the TV screen.

FIG. 2 is a sectional view of a speaker having a conventional magnetic shielding device. The same parts as in FIG. 1 are given the same numbers and their explanations will be omitted. 14 is a canceling magnet magnetized in the opposite direction to the magnet 2; 15 is a magnetic shielding cover whose inner bottom is in close contact with the canceling magnet 14; 12 is a top plate that fits into the end of the magnetic shielding cover; 13 is a magnetic circuit. The operation of the speaker magnetic shielding device configured as above will be explained.

The magnetic circuit of the outer magnet type is basically the same as that shown in FIG. 1, but by providing a canceling magnet 14, the leakage magnetic flux is canceled out and the remaining leakage magnetic flux is allowed to flow to the magnetic shield cover 15. Possibly magnetic shield cover 15
However, in the above configuration, an expensive canceling magnet 14, a large-diameter top play 1,
It is not only necessary to add or change three parts, namely the cover 12 and the magnetic shield cover 13, which makes the cost quite expensive, but also the general speaker shown in Fig. 1 and the speaker shown in Fig. 2 are Since they are separate speakers, they are treated as separate models both in terms of production and management, which poses the problem of extremely inefficiency.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems and aims to provide an extremely efficient magnetic shielding device for a speaker at a low cost.

Structure of the Invention The present invention is a magnetic shielding device for a speaker that includes a speaker having a magnetic circuit and a back chamber made of a magnetic material whose open end is in close contact with the frame of the speaker. The chamber prevents the leakage of magnetic flux from the speaker from leaking to the outside and eliminates the effect on the TV screen.
This back chamber creates a so-called back cavity (sealed space) behind the speaker.
It's another thing.

DESCRIPTION OF THE EMBODIMENTS FIG. 3 shows a sectional view of a magnetic shielding device for a speaker according to an embodiment of the present invention. Since the speaker has exactly the same configuration as in FIG. 1, its explanation will be omitted. 16
is a back chamber whose internal volume is set to prevent internal pressure interference with other speakers and obtain the desired frequency characteristics.Note that this back chamber 16 is normally used in the midrange of a 3-way speaker system. By creating a so-called pack cavity behind the speaker, internal pressure interference with other speakers is prevented. In this embodiment, the back chamber 16 is made of a magnetic material.The operation of this embodiment configured as described above will be described below.

In this embodiment as well, leakage magnetic flux is generated from the magnetic circuit 4 as in the conventional speaker shown in FIG. flows through chamber 16. Therefore, the leakage magnetic flux outside the back chamber 16 is extremely small.0 As described above, according to this embodiment, the back chamber 16 for making the back cavity is made of a magnetic material, which is different from the conventional general case. It is also possible to reduce the leakage magnetic flux of a speaker, and it is possible to realize a magnetic shielding device for a speaker at an extremely low cost that eliminates the influence on the TV screen.Advantageous Effects of the InventionThe present invention provides a magnetic shielding system for a speaker having a magnetic circuit. Since the back chamber is made of a magnetic material, leakage magnetic flux from the speakers can be easily reduced, and even if the speakers are installed adjacent to the TV, there will be no color shift or color unevenness on the screen. In addition, if we consider a speaker with a back chamber that can eliminate the effects of Furthermore, the same speaker can be produced in large quantities regardless of the presence or absence of a magnetic shielding device, so there is no production changeover loss and management is easy. It is possible to realize a device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a general speaker, FIG. 2 is a sectional view of a conventional speaker magnetic shielding device, and FIG. 3 is a sectional view of a speaker magnetic shielding device according to an embodiment of the present invention. 1...Bottom plate, 2...Magnet, 3...Trough plate, 16...
・Back chamber, b...Leakage magnetic velocity. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
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Claims (1)

[Claims] A speaker comprising: a speaker having a magnetic circuit; and a back chamber whose open end is in close contact with a frame of the speaker to form a back cavity behind the speaker, the back chamber being made of a magnetic material. magnetic shielding device.