JP2004241801A - Panel speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a panel speaker suitable for use under an environment with vibration such as application to onboard acoustic apparatuses. <P>SOLUTION: The panel speaker disclosed herein comprises: a magnetic circuit including an inner yoke (Yi), an outer yoke (Yo), and a permanent magnet (M); a moving coil type exciter provided with a voice coil (V) for vibrating inside of a magnetic gap and a bobbin (B) for supporting the voice coil; and a diaphragm (P) to which the tip of the bobbin is fixed, and adopts a vibration mode system wherein bending vibration is excited to the diaphragm. Further, a stopper (ST) for preventing collision between the magnetic circuit and a tip at a free end side of the bobbin by preventing excessive access between the magnetic circuit and the diaphragm is located between the magnetic circuit and the diaphragm (P). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a panel type speaker of a vibration mode (DM) type, and more particularly to a panel type speaker with a stopper suitable for operation under a large vibration environment such as a vehicle.
[0002]
[Prior art]
The present applicant has already filed several patent applications for a vibration mode (DM) panel type speaker (Patent Documents 1, 2, and 3). In this vibration mode type speaker, the tip of a bobbin holding a voice coil of an exciter is attached to the back surface of a flat plate (panel) having a peripheral portion fixed via a soft elastic body, and a magnetic circuit of the exciter is softened. The structure is fixed to a case or the like via the elastic body.
[0003]
FIG. 3 is a sectional view showing the structure of the above-mentioned conventional panel type speaker. This panel-type speaker includes a magnetic circuit including an inner yoke Yi, an outer yoke Yo, and a permanent magnet M to form a magnetic gap between the inner and outer yokes, a voice coil V vibrating in the magnetic gap of the magnetic circuit, and An exciter provided with a bobbin B for holding the voice coil V, and a panel (flat plate) P to which the tip of the bobbin B is fixed with the sub-panel S interposed therebetween.
[0004]
The bobbin B vibrates up and down in the magnetic gap according to the amplitude and phase of the electric signal applied to the voice coil V, and the bending vibration is excited on the panel P to which the tip is fixed. Than reciprocating motion of the front and rear of such a sound system panel, since it mainly the deflection pronunciation vibrations, distribution mode: referred (Di stributed Mo de DM) method, or a vibration mode system. The advantage of the panel speaker of the vibration mode type is that high sound quality and a thin structure can be realized.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H10-243493 (FIG. 1-FIG. 3)
[Patent Document 2]
JP-A-11-331966 (FIGS. 1 and 2)
[Patent Document 3]
JP-A-11-331969 (FIGS. 1 to 3)
[0006]
[Problems to be solved by the invention]
When the conventional panel-type speaker shown in FIG. 3 is used for a vehicle or the like, the free end of the bobbin B collides with the bottom surface of the outer yoke Yo due to externally applied vibration or impact, or the voice coil is damaged, or , The sound quality may be degraded. Assuming that the mechanical resonance frequency of the exciter is Q, if a vibration including the same frequency component is also shocked, Q times of vibration or shock is generated.
[0007]
Externally applied vibrations are suppressed to a considerable extent by a damper D formed between the bobbin B and the magnetic circuit for positioning the bobbin B. However, when the vibration applied from outside is large, there is a problem that the damper D cannot sufficiently suppress the vibration. In addition, if the damper D is relied on too much, a burden is imposed on the damper D, and there is a possibility that the fatigue failure occurs. Accordingly, one object of the present invention is to provide a panel-type speaker that can effectively prevent a collision between a free-side end of a bobbin and a magnetic circuit and a fatigue breakage of a damper even by externally applied vibration. .
[0008]
[Means for Solving the Problems]
The panel-type speaker of the present invention that solves the above-mentioned problems of the prior art includes a stopper that prevents the free end of the bobbin from colliding with the magnetic circuit by preventing the magnetic circuit and the diaphragm from excessively approaching each other. And the diaphragm.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
According to a preferred embodiment of the present invention, the distance between the tip of the stopper and the magnetic circuit or diaphragm facing the stopper is larger than the displacement limit for preventing fatigue of the damper connecting the bobbin and the magnetic circuit. By setting to a small value, it is configured such that fatigue damage of the damper is avoided.
[0010]
According to another preferred embodiment of the present invention, the distance between the tip of the stopper and the magnetic circuit or diaphragm facing the stopper is half the value obtained by subtracting the width of the magnetic gap from the winding width of the voice coil. When the value is set to a value larger than the value (effective vibration amplitude), the linearity of the electroacoustic conversion characteristic is ensured, and good sound quality can be maintained.
[0011]
According to still another preferred embodiment of the present invention, at least a portion of the stopper that contacts the magnetic circuit or the diaphragm is formed of a vibration absorbing material, so that the stopper is generated by a collision between the stopper and the magnetic circuit or the diaphragm. It is configured to absorb and absorb shocks and vibrations.
[0012]
【Example】
FIG. 1 is a sectional view showing a configuration of a panel type speaker according to one embodiment of the present invention. This panel-type speaker includes an internal yoke Yi, an external yoke Yo, and a permanent magnet M, a magnetic circuit that forms a magnetic gap between the inner and outer yokes, a voice coil V that vibrates in the magnetic gap, and a voice coil V And a panel (diaphragm) P to which a tip of the bobbin B of the exciter is fixed via a sub-panel S.
[0013]
The exciter further includes a damper D formed between the magnetic circuit and the bobbin. The exciter is suspended below the panel P, or is fixed to a frame (not shown) or the like while interposing a cushion of a soft elastic body whose back and side surfaces of the magnetic circuit are soft.
[0014]
Further, in the panel-type speaker of this embodiment, a stopper ST made of a vibration-absorbing material such as a column-shaped anti-vibration rubber is fixed on the inner yoke Yi by an adhesive or the like. In the non-operation state of the exciter, the distance between the free end of the bobbin B that is not fixed to the panel P and the bottom surface of the external yoke Yo is β, and the distance between the stopper ST and the panel P is α. If the limit of the displacement for preventing the fatigue of the damper D is Dmax, α <β, Dmax... (.Alpha.) As conditions for preventing the collision of the bobbin tip and preventing the fatigue of the damper D. 1)
Is set.
[0015]
Further, a half of a value obtained by subtracting the width of the magnetic gap (the thickness of the internal yoke Yi in this example) from the winding width of the voice coil V is defined as an effective vibration amplitude Xmax. In order to ensure good sound quality such as the linearity of the electric / acoustic conversion characteristics, the amplitude of the voice coil is set to a value larger than the effective vibration amplitude. As this condition,
α> Xmax (2)
Is set.
[0016]
When the amount of relative displacement between the voice coil V and the magnetic circuit becomes excessive due to vibration or the like due to the traveling of the automobile, the front end surface of the stopper ST collides with the back surface of the opposing panel P. The mechanical shock and vibration generated by this collision are absorbed by the vibration absorbing material constituting the stopper ST and are attenuated. As described above, since the distance between the magnetic circuit and the panel P is kept equal to or greater than the fixed value equal to the height of the stopper ST, the free end of the bobbin B collides with the external yoke Yo, or the bobbin D has A situation in which the deflection exceeds the limit amount of fatigue fracture is effectively avoided.
[0017]
FIG. 2 is a sectional view showing the configuration of the panel type speaker according to one embodiment of the present invention. In this figure, the components denoted by the same reference numerals as those in FIG. 1 are the same as the components already described with reference to FIG. 1, and the duplicate description thereof will be omitted. In this embodiment, a cylindrical stopper ST is formed as a part of a sub-panel S serving as an intervening member for adhering and fixing one end of the bobbin B to the panel P. The tip of the stopper ST is rounded in order to reduce the shock and vibration generated at the time of collision with the internal yoke.
[0018]
In the non-operating state of the exciter, the distance between the tip of the stopper ST and one end face of the internal yoke Yi facing the stopper is set to α. In this case, the relations of equations (1) and (2) hold as in the embodiment of FIG. As described above, since the distance between the magnetic circuit and the panel P is maintained at a certain value equal to or greater than the width on the inner peripheral side of the stopper ST, the free end of the bobbin B collides with the outer yoke Yo, A situation in which the deflection of the damper D exceeds the fatigue limit is effectively avoided.
[0019]
As described above, in both FIG. 1 and FIG. 2, illustration of the support mechanism of the exciter is omitted. However, the back and side surfaces of the external yoke Yo of the exciter may be fixed to a fixing mechanism such as a frame (not shown) with a soft elastic cushion interposed therebetween.
[0020]
【The invention's effect】
As described in detail above, the panel-type speaker of the present invention includes a stopper that prevents the magnetic circuit from colliding with the free end of the bobbin by preventing the magnetic circuit from excessively approaching the diaphragm (panel). Since the configuration is provided between the magnetic circuit and the diaphragm, it is possible to effectively avoid the situation where the voice coil is damaged or the sound quality is deteriorated.
[0021]
According to a preferred embodiment of the present invention, the distance between the tip of the stopper and the magnetic circuit or diaphragm facing the stopper is larger than the displacement limit for preventing fatigue of the damper connecting the bobbin and the magnetic circuit. Since the configuration is set to a small value, fatigue fracture of the damper can be effectively avoided.
[0022]
According to another preferred embodiment of the present invention, the distance between the tip of the stopper and the magnetic circuit or panel (diaphragm) facing the tip is a value obtained by subtracting the width of the magnetic gap from the winding width of the voice coil. Is set to a value larger than half the value (effective vibration amplitude). For this reason, the linearity of the electroacoustic conversion characteristics is secured, and good sound quality is maintained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a panel-type speaker according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a configuration of a panel-type speaker according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a configuration of a conventional panel type speaker.
[Explanation of symbols]
M Permanent magnet Yi Internal yoke Yo External yoke V Voice coil B Bobbin P Panel (diaphragm)
S Subpanel D Damper ST Stopper

Claims (5)

A movable circuit including an inner yoke, an outer yoke, and a permanent magnet, forming a magnetic gap between the inner and outer yokes, a voice coil vibrating in the magnetic gap, and a bobbin holding the voice coil; In a panel-type speaker of a vibration mode type configured by a ring-shaped exciter and a diaphragm to which a tip end of the bobbin is fixed, and exciting a bending vibration to the diaphragm,
A stopper is provided between the magnetic circuit and the diaphragm to prevent a collision between the magnetic circuit and the free end of the bobbin by preventing the magnetic circuit from excessively approaching the diaphragm. A panel type speaker characterized by the above-mentioned. 2. The distance between the tip of the stopper and the magnetic circuit or the diaphragm facing the tip of the stopper is smaller than a displacement limit for preventing fatigue of a damper connecting the bobbin and the magnetic circuit. A panel-type speaker, characterized by being set to: In each of claims 1 and 2,
The distance between the tip of the stopper and the magnetic circuit or the diaphragm facing the stopper is set to a value larger than half (effective vibration amplitude) a value obtained by subtracting the width of the magnetic gap from the winding width of the voice coil. A panel type speaker characterized by being set. In each of claims 1 to 3,
A panel-type speaker, wherein at least a portion of the stopper that contacts the magnetic circuit or the diaphragm is formed of a vibration absorbing material. In each of claims 1 to 4,
The panel-type speaker, wherein the stopper is formed integrally with a sub-panel for fixing the fixed end of the bobbin and the diaphragm.

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