This application also claim the benefit of priority from Japanese Patent Applications No. 2008-008459 filed on Jan. 17, 2008, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to speaker units, and in particular, to a thin type speaker unit having a large diameter.
2. Related Background Art
In recent years, for example, along with the popularization of an extremely thin type TV such as a liquid crystal screen TV and a multichannel car stereo, and the like, a request for thinness of speaker units has been increasing. As an example of the conventional thin type speaker unit, a speaker shown in
A basic structure of the conventional thin type speaker unit will be described with reference to
A diaphragm 121 includes an inner conical portion 122 opened upward of the figure which is a speaker front direction, an outer conical portion 123 opened downward which is a back face direction, and a connecting portion 124 connecting both of the conical portions. An outer edge of the outer conical portion 123 is provided with an edge 125. Inside the inner conical portion 122, a center cap 126 is bonded. Downward the center cap 126, a connecting portion 127 of the inner most end of the diaphragm 121 is connected with one end of a voice coil bobbin 128. An overlapping area 137 in the midst of the voice coil bobbin 128 is bonded with a damper 129. The damper 129 holds the voice coil bobbin 128 at its central axial line, while allowing a mechanical reciprocating movement (vibration) converted from an electrical input by conversion means 130 located below thereof.
The conversion means 130 includes a voice coil 131 wound around at the bottom of the voice coil bobbin 128, and a magnetic field portion 132 providing a strong magnetic field to the voice coil 131. The magnetic field portion 132 includes a magnet 133 serving as a permanent magnet, a plate 134, and a pole piece (yoke) 135, thereby forming a magnetic circuit of an outer magnetic type. The voice coil bobbin 128 is inserted into an upright portion of the pole piece 135, and an electromagnetic force corresponding to the current is given to the voice coil 131 from the magnetic field inside a magnetic space (magnetic gap), which is formed between the inner peripheral surface of a penetration-hole formed in the plate 134 and the outer surface of the upright portion of the opposing pole piece 135. An outer edge side of the edge 125, the outer edge side of the damper 129, and the bottom of the pole piece 135 are supported by a frame 136.
Now, in such conventional speaker, by vibrating (vertically in
In this manner, the vertical movement of the voice coil bobbin 128 moves in the direction other than vertical due to the resonance and the like of the edge 125+the diaphragm 121+the voice coil 131. To prevent this rolling phenomenon, the voice coil bobbin 128 is connected with the damper 129, thereby to secure straight-advancing property of the voice coil bobbin 128. Unless the straight-advancing property of the voice coil bobbin 128 is secured, the voice coil bobbin 128 is brought into contact with the plate 134 and the like, thereby to cause abnormal noise and damage. Further, when the magnetic gap is made large so as not to cause such situation, the magnetic force is reduced to be followed by the reduction of sound pressure.
To solve such problem, that is, to suppress the vibration other than one way direction, and to hold the voice coil bobbin 128, the damper 129 is provided.
However, to bond the damper 129 to the voice coil bobbin 128 (bonding at one point is difficult, and generally, a method of a so-called padding is used), a broadish space (the overlapping area 137) to bond the damper to the voice coil bobbin 128 is required. Further, in the speaker of a wide diameter, since a vibration width in one way direction of the voice coil bobbin 128 reaches even several tens mm, unless the distance between the magnetic gap and the damper 129 takes into consideration this vibration width also, the damper 129 interferes with other members, thereby to cause damage and abnormal noise. Hence, it is necessary to provide a sufficient space for securing the vibration range of the damper 129 inside the speaker unit 120.
That is, in the conventional speaker, to suppress the rolling phenomenon, the damper 129 is required, and a broad overlapping area 137 for adhering this damper 129 to the voice coil bobbin 128 is required. Further, a space for securing the vibration range of the damper 129 is required, and this becomes a big obstacle to the thinness of the speaker.
The present invention has been carried out in view of such problems, and an object of the invention is to provide a speaker unit capable of being further thinned.
To achieve the above described object, the speaker unit of the present invention includes a voice coil through which an input signal, a magnetic circuit disposed at a predetermined interval so as to sandwich the voice coil and the voice coil bobbin from the inside and outside, a diaphragm connected to any of upper and lower sides of the voice coil bobbin, and a damper not connected to the voice coil bobbin and connected to the outer edge portion of the diaphragm and suppressing a rolling phenomenon of the voice coil bobbin.
Further, the speaker unit of the present invention, in addition to the above described invention, has a damper which is configured by an inner peripheral plate and an outer peripheral plate concentrically formed by two circular thin plates different in diameter, and a connecting plate for connecting the inner peripheral plate and the outer peripheral plate, and a diameter of the inner periphery of the inner peripheral plate is configured to be larger than the diameter of the voice coil.
Further, the speaker unit of the present invention, in addition to the above described invention, has a damper which is printed or bonded with a conductive layer, and is preferably configured such that an input signal is supplied from the damper to the voice coil.
Further, the speaker unit of the present invention, in addition to the above described invention, has a damper having preferably a hybrid structure made of a plurality of layers different in materials.
Further, the speaker unit of the present invention, in addition to the above described invention, has a damper whose shape in the connecting portion between the damper and the diaphragm is preferably taper-shaped to conform to the shape of the diaphragm.
According to the present invention, it is possible to make a speaker unit further thinned.
The basic structure of a speaker unit according to the embodiment of the present invention will be described below.
As shown in
The diaphragm 2 is connected to an inner conical portion opened upward in the figure which is a front surface direction of the speaker unit 1 and the outer periphery of the inner conical portion, and includes an outer conical portion opened downward which is a back face direction. The outer edge of the outer conical portion is provided with the edge 3. Below the edge 3, the butterfly damper 4 is provided. The butterfly damper 4 and the outer conical portion of the diaphragm 2 are mutually connected. The butterfly damper 4 holds the voice coil bobbin 5 on its central axial line (not shown), while allowing a reciprocating movement (reciprocating vibration) of the voice coil bobbin 5 based on the input signal flowing through the voice coil 6 which is wound around the voice coil bobbin 5.
On the outside of the voice coil 6, the top plate 7 and the magnet (preferably a permanent magnet) 8 are loaded and disposed at an interval (magnetic gap) in order from above as shown in
As shown in
Further, since a length in the vertical direction of the voice coil bobbin 5 can be made short, a gravity center position of a vibration system is made close to a drive point (voice coil 6), thereby making it more easier to avoid a rolling phenomenon. Further, since a necessity of attaching the damper to the voice coil bobbin 5 is eliminated, the voice coil bobbin 5 can be made light in weight, so that a voice response to the input signal can be improved.
Further, as the material of the butterfly damper 4, glass epoxy and resin such as bakelite or metal such as aluminum and stainless can be adopted. For example, when the butterfly damper 4 made of resin is adopted, the butterfly damper becomes soft and light in weight. On the other hand, when the metal made butterfly damper 4 is adopted, the butterfly damper 4 becomes hard and heavy in weight. In this manner, by changing the material of the butterfly damper 4, acoustic characteristics of the speaker unit 1 can be changed.
Further, by printing or bonding a copper foil and the like on the butterfly damper 4 or coating it with a conductive coating, the butterfly damper 4 may be turned into a so-called [conductive damper]. In the present embodiment, since the butterfly damper 4 is not connected to the voice coil bobbin 5, to supply the input signal to the voice coil 6, a terminal provided in the frame of the speaker unit 1 and the copper foil of the butterfly damper 4 are connected, and two methods of either (1) connecting the input signal to the voice coil 6 by using a tinsel wire from the inside of the butterfly damper 4 or (2) printing the copper foil on the back of the diaphragm 2 and introducing the input signal finally to the voice coil 6 through the back of the diaphragm 2 can be adopted.
By adopting such configuration, it is possible to omit the tinsel wire or make it short. Further, since there is no possibility of the tinsel wire at least extending to the voice coil 5 of the center portion from the outside (frame terminal) of the speaker unit 1, the driving members (the voice coil, the damper, and the diaphragm) of the speaker are also not brought into contact with the tinsel wire, and the possibility of generating abnormal noise can be reduced.
Further, the shape of the butterfly damper 4 side in the connection portion between the butterfly damper 4 and the diaphragm 2 may be taper-shaped by conforming to the shape of the diaphragm 2. Because of this taper-shape, the connection of the butterfly damper to the diaphragm 2 is made by a bonding agent, but this can be also used as an overlapping area, and therefore, bonding strength can be also increased.
Further, the butterfly damper 4 may be turned into a hybrid structure having a plurality of layers different in materials. By configuring the butterfly damper 4 by the plurality of layers different in materials, a span of adjustable range of tone quality can be expanded depending on a combination of the layers.
In place of the butterfly damper 4, a damper of the configuration concentrically repeating unevenness may be adapted.
Number | Date | Country | Kind |
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2008-008459 | Jan 2008 | JP | national |