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The present invention relates to the improvement of a diaphragm for a speaker, and in particular,
it is an object of the present invention to provide a dog-free fine plate with high internal loss and
rigidity, which has high heat resistance. It is well known that the speaker retracting plate is
required to have high rigidity, light weight, and high internal loss, but in addition to this, good
things of 1m1 thermal property and 1ljJ humidity are required for practical use . Conventional
diaphragms for speakers are (IHdL, (2) metal foil, (31 synthetic resin etc. are often used)-When
looking at such conventional diaphragms from the motion point, +11 is lightweight Have the
disadvantages of low rigidity, relatively low internal loss, and extremely low moisture resistance,
and (2) high rigidity and good heat resistance and moisture resistance, but internal loss Because
it is extremely small, it is difficult to obtain flat frequency characteristics, and it also has the
disadvantage of large weight, and in (3) history, polypropylene and polycarbonate are recently
used in history, and it is lightweight and internal loss is an appropriate value. Although the point
and moisture resistance are excellent, they have an advantage which has not been conventionally
used, but they have a defect that the rigidity is insufficient and the heat resistance is bad. For
example, the heat distortion temperature of the polyester resin is 76 ° C. and 80 ° C. to 90 °
C., and heat deformation occurs to generate voice coils (which generate an abnormal amount.
Also, before that, when the temperature reaches about 70 ° C. or more, the Young's modulus
sharply decreases to affect the sound quality. In particular, when using polyester resin V resin as
a diaphragm of a vehicle-mounted speaker, it is conceivable that the temperature may reach 90
° to 100 ° in, for example, Ar Arase A / l-Ray, etc., causing thermal deformation and disabling
the speaker It also happens when you get to Therefore, in the present invention, the first problem
is solved by using a polyetherimide resin having excellent heat resistance as a diaphragm for a
speaker, and in the second invention, the second substrate of the polyetherimide resin is used as
a diaphragm substrate The rigidity is further enhanced by forming an inorganic highly elastic
skin 1 such as metal or ceramic on at least one surface of the diaphragm substrate, and the
reproduction frequency range is expanded. The embodiments will be described in detail below.
Physical Properties of the Polyetherimide Resin Film Used in the Invention and the Conventional
Polyester Film First (However, the heat distortion temperature is according to ASTM: D648) As is
apparent from Table 1 of Table 1, it can be used for the invention rolling plate The
polyetherimide resin film is extremely high in heat distortion temperature compared with
polyester ρ and extremely excellent in heat resistance characteristics, and is useful as a
diaphragm of an on-vehicle speaker or the like used under high temperature.
Although the Young's modulus is slightly reduced, the internal loss is larger than that of the
polyester, which results in a large absorption of divided vibration energy and suppresses the
occurrence of harmful peaks and dips on the frequency characteristics to make the frequency
characteristics more flat. You can expect to gain. Example 1 A 100 μm thick polyetherimide
resin film is placed between upper and lower molds at room temperature and heated to 240 ° C.
to 250 ° C. by far-infrared heater, then the heater is removed and the upper and lower molds
are immediately aligned. The pressure was applied at a pressure of about 51 j / cJ to obtain a
cone-shaped diaphragm having an aperture of 8 (7), and frequency characteristic 1 of a speaker
incorporating it was measured (FIG. 1). As a comparative example, frequency characteristics 2 of
a speaker incorporating a polyester resin resin micro-motion plate having the same diameter and
the same shape were measured (FIG. 1). The frequency characteristic 1 of the speaker equipped
with the diaphragm according to the present invention in FIG. 1 is compared with the
characteristic 2 of the speaker equipped with the polyester resin diaphragm, particularly in the
frequency band from 800 Ilz to 110017 which is called middle valley The dip was suppressed,
and a flatter frequency characteristic could be obtained. Next, in order to further increase the
rigidity, a diaphragm is formed on which at least one surface of the polyetherimide resin
diaphragm described above is formed with an inorganic high elastic film such as a metal such as
aluminum or titanium or a ceramic such as alumina or zirconia. An example will be described.
[Example 2] A diaphragm substrate of the same diameter and shape is formed by the same
forming method as in the above-mentioned embodiment using a polyetherimide resin film having
a thickness of 100 μm, and placed on a substrate provided in a container of high frequency nub
Then, while the substrate is water-cooled, the inside of the container is depressurized to a degree
of vacuum of 5 × 10 ′, t, or r, and the temperature is raised to 150 ° C. A high frequency
power (13, 56M11 ·) of 100 W is applied to the open (A swamp) open to cause discharge to be
disclosed between the substrate and the tagger V to perform high frequency sputtering. The
high-frequency switch (by performing 30 minutes of filtering) 1 μm J? Formed an aluminum
film. The above-described process was performed on the other surface of the diaphragm
substrate to form an aluminum film (1 μm) on both surfaces of the diaphragm substrate (100
μm thick). [Example 2] The same diaphragm substrate as in Embodiment 1 is subjected to high
frequency nupantaling for 2 and 5 h similarly using a target of oJ and fi-82 gap as a target to
form an alumina film of 18 thickness difference on one surface of the diaphragm substrate. Then,
in the same manner, the other surface of the diaphragm was subjected to the same treatment to
form an alumina film of 18 thick thickness on both surfaces of the diaphragm substrate (100
The physical properties of the diaphragms obtained in Examples 2 and 3 were measured, and the
results shown in Table 2 were obtained (note that the physical properties of the polyester resin
diaphragm are shown as a comparative example). According to the present invention, it is
possible to significantly increase the Young's modulus without changing the density and the tan
δ, as compared with the poly ente) v resin diaphragm. Next, FIG. 2 shows frequency
characteristics of a speaker incorporating Examples 2 and 3 (note that Example 2 is 21 in the
figure, Example 3 is 22 in the figure, and a polyester resin diaphragm is incorporated as a
comparative example). 1. "Braz" is shown at 23). As is apparent from the figure, according to the
diaphragm of the present invention, the high frequency reproduction limit frequency (fh) can be
increased and the reproduction frequency bandwidth can be expanded, and the heat resistance
characteristic becomes the diaphragm base Depending on the heat distortion temperature of
polyetherimide resin, it is almost '/ P, so it can be used well even under high temperature
conditions such as in a car, etc. And the heat dissipation of voice coil is promoted by metal or
ceramic film, so the input resistance characteristics are improved. I was able to. In addition, metal
or ceramic coatings are commonly used in the prior art, as are the upper layers f) 17. It is
desirable to form by pantering. That is, the high frequency sputtering is a fine step and can form
a film having good adhesion with the diaphragm substrate, so that the film has a high Young's
modulus, a high micromotion plate has high rigidity, and a large entrance. Also, it is possible to
provide a durable speaker with no base and coating flaws. Also, in order to form a coating on the
surface of the synthetic resin in such high frequency sputtering, it is necessary that the synthetic
resin does not thermally deform at least to a temperature of 180 to 190 'in the case of alumina
and film formation in Example 3. Although conventional polyester and nutyl resins can not form
a film by high frequency sputtering, they can be achieved by using polyetherimide resin having a
high heat distortion temperature, as described above. The invention is a diaphragm formed by
molding a polyetherimide resin and a diaphragm having an inorganic high elastic film formed on
at least one surface of the diaphragm, and a speaker having good heat resistance and flat
frequency characteristics, Can be provided, and by forming a mineral high elasticity film 11! As
well as improving the input resistance and expanding the reproduction bandwidth due to the
increase in fH, it is particularly suitable for the diaphragm of a car-mounted speaker used under
high temperature conditions.
Brief description of the drawings
1 and 2 are frequency characteristic diagrams of a speaker provided with the diaphragm of the
present invention and the polyester resin diaphragm, respectively.
Patent Assignee Onkyo Co., Ltd. Agent Chi Satoshi Satoshi Satoshi Department