JP4472573B2 - Speaker - Google Patents

Description

  The present invention relates to a thin speaker provided with an open type magnetic circuit.

  FIG. 11 shows a conventional open type magnetic circuit. In a normal magnetic circuit of a speaker, a voice coil is arranged in a magnetic gap formed in the magnetic circuit. In an open type magnetic circuit, a voice coil is arranged outside the magnetic circuit. In the figure, 1 is a main magnet whose upper part is magnetized to the S pole, and the lower part is magnetized to the N pole. 3 is a pole piece provided on the upper surface of the repulsion magnet 2, 4 is a plate sandwiched between the main magnet 1 and the repulsion magnet 2, and 5 is a main It is a bottom pole piece provided on the bottom surface of the magnet 1, and the magnetic flux flows as shown by arrows.

  FIG. 12 shows a vibration system such as a voice coil, a voice coil bobbin, and a damper incorporated in the open type magnetic circuit. The voice coil 7 is spaced apart from the outside of the plate 4. When the voice current is applied, the voice coil 7 vibrates and is connected to a voice coil bobbin 8 supported by a damper 9 so as to vibrate (see FIG. (Not shown) is configured to oscillate and emit sound waves.

  When the Nd—Fe—B magnet is used, the permeance coefficient of the magnet in the open type magnetic circuit having the above configuration is about 0.8 at maximum as shown in FIG.

  In order to increase the permeance coefficient, it is necessary to reduce the ratio of the cross-sectional area and the height of the magnet. For this purpose, in order to reduce the cross-sectional area of the magnet, it is necessary to increase the inner diameter of the magnet or increase the thickness of the magnet.

  However, if the inner diameter of the magnet is increased, the magnetic flux density on the outer periphery of the magnet will decrease, and if the magnet thickness is increased, the volume of the magnet will increase, the magnetic circuit will become larger, and the cost will increase significantly. There was a problem of end.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a thin speaker having an open magnetic circuit with an improved permeance coefficient without causing an increase in cost.
Further, a thin speaker provided with an open type magnetic circuit in which a reverse magnetic field in the amplitude region of the voice coil is reduced is provided.
Furthermore, the present invention provides a thin speaker equipped with an open type magnetic circuit that can be applied to an existing open type magnetic circuit and can reduce the cost.

The invention of claim 1 has a main magnet and a repulsion magnet, a plate is provided between them, a pole piece is provided on the top surface of the repulsion magnet, and a bottom side is provided on the bottom surface of the main magnet. In a thin speaker with an open magnetic circuit with a pole piece and a vibration system with a voice coil on the outer circumference, the outer circumference of the bottom pole piece has a ring shape. The above object is achieved by providing a pole piece part made of a magnetic material having a high magnetic permeability.
According to a second aspect of the present invention, in the thin speaker according to the first aspect, the pole piece component is substantially ring-shaped, the bottom surface is substantially flush with the bottom pole piece bottom surface, and the outer peripheral side of the top surface faces the front side. It is formed in an inclined taper shape, and the inner end of the upper surface is formed in a shape continuous with the upper surface of the bottom pole piece.
According to a third aspect of the present invention, in the thin speaker according to the first aspect, the pole piece part is a separate part and is joined to the outer periphery of the bottom side pole piece.
According to a fourth aspect of the present invention, in the thin speaker according to the first aspect, the pole piece part is integrally formed on an outer peripheral portion of the bottom side pole piece.

  In the first aspect of the invention, since the pole piece component having high permeability is attached to the outer peripheral portion of the bottom side pole piece of the open type magnetic circuit, the size of the magnet can be increased without increasing the inner diameter of the magnet or increasing the thickness. Even if it is not changed, the permeance coefficient can be improved by simply adding parts while reducing the thickness. Further, the reverse magnetic field in the amplitude region of the voice coil can be reduced.

  According to invention of Claim 2, since the upper surface of the pole piece component was made into the taper shape, contact | abutting to a damper can be avoided.

  According to the invention described in claim 3, since the pole piece component is a separate component, it can be applied to an existing open type magnetic circuit and is versatile.

  According to the invention described in claim 4, since the pole piece part is integrally formed with the bottom side pole piece, there is an advantage that the permeance coefficient is further improved as compared with that of the separate type and the manufacture is easy.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
FIG. 1 shows a first embodiment of an open type magnetic circuit used for a thin speaker of the present invention.

  The present invention is characterized in that a substantially ring-shaped pole piece part 6 made of a magnetic material having a high magnetic permeability is attached to the outer peripheral portion of the bottom pole piece 5.

  Since other configurations are the same as those in FIGS. 11 and 12, the same members are denoted by the same reference numerals.

  It is preferable to use the same material as that of the bottom pole piece 5 as the material of the pole piece part 6.

  The inner peripheral surface 6a of the pole piece component 6 is formed to have substantially the same thickness as the outer peripheral surface of the bottom pole piece 5, and is joined to the outer periphery of the bottom pole piece 5 with an adhesive.

  The bottom surface 6 b of the pole piece component 5 is substantially flush with the bottom surface of the bottom pole piece 5 when joined to the bottom pole piece 5.

  Further, the outer peripheral surface 6d of the pole piece component 6 has a larger axial dimension than the inner peripheral surface 6a, and the outer peripheral side of the upper surface 6c extends toward the front side of the speaker, whereby the upper surface 6c is tapered. Forming. Since the taper is formed in this way, it is possible to avoid the contact with the damper when the vibration system has a large amplitude. Also, by providing this pole piece component 6, the reverse magnetic field in the amplitude region of the voice coil can be reduced.

  A simulation result indicating this is shown in FIG. FIG. 3 shows the magnetic flux density distribution in the gap of a conventional open type magnetic circuit without the pole piece component 6. In the first embodiment of the present invention, the permeance coefficient could be improved from 0.8 to about 25% even when the same size magnet was used. Moreover, the reverse magnetic field in the amplitude region of the voice coil could be reduced.

  FIG. 4A shows the flow of magnetic flux in the open type magnetic circuit in the first embodiment of the present invention, and FIG. 4B shows the flow of magnetic flux in the conventional example.

  FIG. 5A shows a magnetic flux density distribution diagram of the open type magnetic circuit in the first embodiment of the present invention. The closer to blue A → sky blue B → blue B ′ close to green → green C → yellow D → orange E → red F, the denser the magnetic flux. FIG. 5B shows a conventional example. In the present invention, as a result of providing the bottom pole piece component 6, the green C region of the bottom pole piece 5 is increased, the magnetic flux density is improved, and the magnetic flux density of the main magnet 1 portion is also improved.

[Embodiment 2]
FIG. 6 shows a second embodiment of the present invention. This embodiment is characterized in that the pole piece component 6 is integrated with the bottom pole piece 5 at a position avoiding contact with the damper at the time of amplitude. The pole piece portion 6 is provided at a position avoiding contact with the damper.

  FIG. 7 shows the simulation result of the second embodiment. FIG. 8A shows a flow of magnetic flux, and FIG. 8B shows a distribution diagram of magnetic flux density. The magnetic flux density was improved from that in the first example.

  Further, in this second embodiment, the permeance coefficient could be further improved by 30% or more compared to the first embodiment shown in FIG. Further, in this embodiment, as shown in FIG. 7, there is no reverse magnetic field in the downward direction.

  FIG. 9 is a plan view of an in-vehicle thin speaker equipped with the open type magnetic circuit of the second embodiment, and FIG. 10 is a side sectional view of the side.

  The substantially planar diaphragm 10 is supported by a frame 12 via an edge 11 provided on the outer periphery thereof. The upper outer peripheral portion of the voice coil bobbin 8 is coupled to the neck portion 10a of the diaphragm 10, and the voice coil 7 is provided on the outer peripheral side of the plate 4 of the open type magnetic circuit. Further, the bottom pole piece 5 of the open type magnetic circuit is provided in the opening at the bottom center of the frame 12.

  In addition, in FIG. 9, 13 is a dust-proof cap, 14 is a mounting hole provided in the outer peripheral part of the frame 12, and a is a recess formed in the bottom pole piece 5 for preventing contact with the damper.

1 is a half sectional view of an open type magnetic circuit of a first embodiment used for a thin speaker of the present invention. The simulation result of the permeance coefficient of the said Example is shown. The simulation result of a prior art example is shown. (A) shows the flow of magnetic flux in the open type magnetic circuit of the first embodiment of the present invention. (B) shows the flow of magnetic flux in the conventional example. (A) is a magnetic flux density distribution diagram of the open type magnetic circuit of the first embodiment of the present invention, and (b) shows a conventional example. The half sectional view of the 2nd example of the open type magnetic circuit used for the present invention is shown. The simulation result of the said 2nd Example is shown. (A) shows the flow of magnetic flux in the second embodiment. (B) shows a magnetic flux density distribution diagram. The front view of the thin speaker of this invention is shown. The half sectional view of the thin speaker of the present invention is shown. The half sectional view of the conventional open type magnetic circuit is shown. A half sectional view of a conventional open type magnetic circuit in a state where a vibration system is incorporated is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main magnet 2 Repulsion magnet 3 Pole piece 4 Plate 5 Bottom side pole piece 6 Pole piece component 6a Pole piece component inner peripheral surface 6b Pole piece component bottom surface 6c Pole piece component upper surface 6d Pole piece component outer peripheral surface 10 Diaphragm 11 Edge 12 Frame 13 Dust-proof cap

Claims (4)

It has a main magnet and a repulsion magnet, a plate is provided between them, a pole piece is provided on the top surface of the repulsion magnet, and a bottom pole piece is provided on the bottom surface of the main magnet. In a thin speaker equipped with an open type magnetic circuit and provided with a vibration system including a voice coil on its outer peripheral side,
A thin-type loudspeaker characterized in that a pole piece component made of a magnetic material having a high magnetic permeability is provided on the outer periphery of the bottom pole piece.   2. The thin speaker according to claim 1, wherein the pole piece component is substantially ring-shaped, the bottom surface is substantially flush with the bottom pole piece bottom surface, and the outer peripheral side of the top surface is formed in a tapered shape inclined toward the front side. The thin speaker is characterized in that the inner end of the upper surface is formed in a shape continuous with the upper surface of the bottom pole piece.   2. The thin speaker according to claim 1, wherein the pole piece component is a separate component and is joined to an outer peripheral portion of the bottom pole piece.   2. The thin speaker according to claim 1, wherein the pole piece component is integrally formed on an outer peripheral portion of the bottom pole piece.

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