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Specification 1, Name of the Invention Speaker diaphragm 1, speaker made of foam or hollow
porous composite material formed by adding nucleating agent and low Young's modulus metal to
polyamide resin to form transformation twin crystal. Vibration plate.
2, the scope of claims
3. Detailed Description of the Invention The present invention relates to a novel speaker
diaphragm using a foamed resin. To play a faithful sound in the speakers. It is desirable that the
diaphragm of the speaker perform piston operation over a wide range. For this purpose, it is
advantageous to use a diaphragm which is light and hard in nature. That is, assuming that
Young's modulus is E and density is ρ, the larger E / E is more advantageous. In the past, a) a
large key metal of / ρ, such as aluminum, titanium, beryllium, etc., has been used as a
diaphragm of a high sound speaker having a small diameter. However, VC for use in large φ low
/ mid tone speakers ! Because it is necessary to maintain the bending strength of the entire wide
i diaphragm, it is necessary to increase the thickness of the diaphragm, so the mass of the whole
diaphragm increases, and this fL has a large aperture diameter of metal. It was an obstacle when
applied to speakers. Therefore, various diaphragms using a foamed synthetic resin have been
developed in order to increase the thickness and increase the rigidity. As this foamed synthetic
resin body, expanded polystyrene, expanded polyurethane, polyethylene. Among them are vinyl
chloride, polyvinyl acetal, acrylic foam resin, etc. Among them, @ foam polystyrene. Foamed
polyurethane, an acrylic foam material, etc. are used as a diaphragm for speakers. Because the
foam is made of these materials, 11 (? In the case of fixed binding 1) It is possible to increase the
bending rigidity as compared with a normal paper cone or the like. Therefore, in a low frequency
region up to several hundreds of hertz, the diaphragm has a flat single frequency characteristic
and produces integral vibration with less distortion. EndPage: 1 However, generally, if Young's
modulus Z of foam is 1 $ Young before Young's foaming, empirically, it is empirically expressed
by elder brother (1-p) · uo (where P is a foaming ratio). After foaming, the LD1 elastic modulus
and mechanical strength decrease significantly. Therefore. In the low frequency region of several
hundreds of hertz, it is resonated with the diaphragm and divided into six parts? Start to occur.
When it enters into the normal and n, division vibration bands, a peak dip is generated on the
resonance of the diaphragm in terms of frequency characteristics, and harmonic distortion is also
increased to adversely affect the acoustic characteristics. I / r which suppresses this resonance as
much as possible, a material that absorbs and attenuates vibration energy and converts it into
heat energy. That is, a material having a large mechanical loss is desired. Since one foam is made
of the above-mentioned conventionally used foam resin, mechanical loss is large as compared
with the non-foamed one.
However, the effect of absorbing and attenuating the vibrational energy is still small, and the
vibration and distortion due to the one-division vibration also considerably occur at frequencies
of several hundred hertz or more. The present invention has been made in view of this point. It is
an object of the present invention to provide a diaphragm tube for a foamed tie speaker, which
has a great effect of damping vibrational energy and therefore is very easy to absorb resonance.
As a method of obtaining a material having excellent damping characteristics, a composite
material in which two materials having different properties are mixed is effective. For example,
when vibration is applied to an interface where a hard material and a soft material are in contact
with each other, plastic flow occurs to damp the vibration. In addition, even as a soft material, it
is preferable that the material itself has a large vibration damping force. By utilizing this fact, a
composite material having a very large damping force can be obtained in a material obtained by
adding a low Young's modulus metal 1 such as lead powder which is soft and has a large
damping force to a hard resin. Presently-Lead powder and nucleating agent are added to
polyamide resin, and when vibration is applied to this transformation twin structure, plastic flow
occurs in one of the above to damp the vibration. Furthermore, when the resin itself is subjected
to vibration, molecular motion Yr is induced to be converted into vibration energy f thermal
energy and diffuse heat radiation around 1 to attenuate the vibration. Also, lead itself has a large
damping damage due to the low Young's modulus metal, and these dampings exert a synergetic
effect to obtain a very large damping force. In order to foam the composite material, for example,
a method of mixing a thermal decomposition type foaming agent such as azodicarbonamide into
the composite material and subjecting it to heat foaming, or processing of methyl ether into the
composite in the molten state is carried out. A closed-cell foam can be easily obtained by a
conventionally known method such as a method in which pressure is released and foaming is
performed after the foaming agent is pressed. Furthermore, the open-cell porous material can be
produced using a salt elution method or a sintering method. Incidentally, when the lead fID is
added, the non-foamed body of the present composite material and the styrene resin (The
characteristics of the light-emitting body are as shown in the following table. Young's modulus
logarithmic damping ratio composite material to 23 OK f 20.25 styrene resin 200 to 300 Kf / ll
112 0.05 As can be understood from the above table, the composite material has almost the
same stiffness of the thigh as the styrene resin in Young's modulus, and the damping It is
extremely effective at absorbing the resonance of the diaphragm and reducing one-part vibration,
with a force that is five times as large as 5 ° C. ! The foam molding process can be performed
under the same conditions as general foamed resin. When using a porous body of one composite
material as a diaphragm, a thin film is coated on both sides or one side of the porous body to
make 1 air permeability.
In this process, lead powder and a nucleating agent are added to a polyamide resin to form a
transformation twin, and the resulting composite material is foam-formed to form a vibrating
plate which is extremely resonant. As apparent from the above description, the diaphragm for a
speaker according to the present invention is contained in the foam or porous body of a
composite material in which a nucleating agent and a low Young's modulus metal are added to a
polyamide resin to form transformation twins. Because In addition to maintaining the flatness of
the frequency characteristics, distortion can also be reduced, and the acoustic characteristics of
the Sveker EndPage: 2 can be improved. Patent Applicant Sanyo Electric Co., Ltd. Representative
Igei 485-EndPage: 3