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Within Tokyo Shibaura Electric Research Institute. Patent No. 1 Kawa Ayato name (307) Tokyo
Shibaura Electric Co. rL · Representative 8 Tamaki Keiko 7 (Other 4 people) [Fa] Japan Patent
Office 0 JPA 52-170120 published Japan. 52. (I977) 2.3 Internal reference number 〆 (where
btt-Jr → 呵-description 1, title of the invention
Method of manufacturing dome-shaped diaphragm
3. Detailed Description of the Invention The present invention relates to a method of
manufacturing a dome-shaped vibration plate for use in a sound III device. In general, a
diaphragm that converts an electrical signal into sound has vibration characteristics determined
by the material that forms the diaphragm. This vibration characteristic is determined by the ratio
of the elastic modulus E of the material to the specific charge 、, that is, the size of the specific
elastic modulus (Blp value), and the larger the specific elastic modulus, the more uniform the
vibration characteristic is obtained in the high frequency region Can. In addition to the high
specific modulus of elasticity of the material that forms this, the vibration diaphragm vIJIlr! From
the top of the rate, it is claimed that the diaphragm itself has a small electric charge. Therefore, in
recent years, p, a light alloy such as an alloy or a Ti alloy has come to be used as a material of the
diaphragm. However, the diaphragm made of these light alloys has a problem that multiple
resonances occur in the reproduction frequency band and the sound quality is impaired, for
example, in the case of reproducing a band from middle to high sound with one speaker (in the
case of a two way speaker). Even for a high acoustic diaphragm, ti = dynamic characteristics in a
band of 20 kHz or less is sufficient for steady sound reproduction, but high frequency
components are included in transient waveform reproduction There is a possibility that the
resonance phenomenon may occur here. For this reason, a diaphragm having stable
characteristics in a wide band is being developed in recent years using a Be alloy having a
specific elastic modulus higher than that of an alloy p, etc. However, the Be alloy is expensive as
well as toxic. It is not a strong and desirable material. EndPage: 1 In view of the point of turbidity,
it is considered as a material with a high specific elastic modulus, such as B (boron) etc. to form a
diaphragm as well, but B is an A-no alloy which has been used in place However, it is difficult to
form into a dome shape by six-piece machining, which has different hard and brittle properties.
In the present invention (-i, as a result of intensive research to eliminate such defects, a
diaphragm having a high specific elastic modulus S material is chemically vapor deposited on the
inner surface of a quartz dome substrate to form a dome shape. It is an object of the present
invention to provide a method of manufacturing a dome-shaped diaphragm excellent in
productivity, by forming it and forming a special vibration together with vibration in a high
frequency range. In the present invention, after forming a coating consisting of Cr, C, W or Mo on
the inner surface of a dome-shaped substrate consisting of quartz, a material having a high
specific elastic modulus of 2600 (K7 / gy2) on the surface of said M 屯Chemical steam to form a
dome-like precipitate, and after this? To separate the precipitate from the substrate by utilizing
the thermal expansion difference ((The method for producing a dome-shaped diaphragm will be
described in detail according to the following steps.
First, Cr, C, W or W which combines the releasing action with the substrate and the deposition of
a substance having a high specific elastic modulus by plating or evaporation on the inner surface
of the dome-like substrate made of quartz. Form a coating such as Mo. The thickness of this film
can be sufficiently achieved by the thin layer of 0.5 μm 8 °. Next, the dome-like substrate with
the coating formed on the inner surface as described above is placed in the reaction vessel and
heated to 800 to 1250 ° C., preferably 1000 to 1100 ° C., and chemical vapor deposition is
performed in good condition. By depositing B, SiC, BN, Tic, TiN or TiB2 with a high specific elastic
modulus of at least 2600 (Kp / u2) to a thickness of 40 to 100 μm to form a dome-shaped
precipitate that becomes a diaphragm Form. In the present invention, as a method of depositing a
substance having a high specific elastic modulus on a surface of a film by chemical vapor
deposition using Cr or the like, for example, 7% of 0 boron such as BCl 3.8 Br 5 or BI 2. By
flowing a mixed gas of 羨: and B2 gas, which acts to reduce it, into the reaction vessel, it is
subjected to reductive decomposition as shown in the following formula, for example, on the
surface of the film heated to a high temperature. To precipitate B. As a method of depositing
substances other than B as a material of ZBCl + 3 H 2 → 2 B + 6 HC 1 9 diaphragm by chemical
vapor deposition, for example, in the case of depositing SiC, mixed gas consisting of 5iCt, CH 4
and H 2 is passed through the reaction tank to reduce Or a method in which a mixed gas of
5SiCZ 5 and an inert gas is passed and pyrolyzed. When BNft is precipitated, BCl, B2. In the case
of depositing Tic using a mixed gas of N 2, TiCl 4. A mixed gas of C6H5CH3 and B2 is used.
When TiN is to be deposited, the mixed gas of TrC14 and BBr5 is passed through the reaction
vessel to carry out reductive decomposition. Next, as described above, in the reaction vessel, the
inner surface of the dome-like substrate is cooled by forming a dome-like precipitate via a
coating that combines the mold release action and the precipitation promoting action. Since the
thermal expansion coefficient of quartz is extremely small compared to the dome-like precipitate
by this cooling, the precipitate can be easily separated from the substrate to obtain a dome-like
diaphragm. In the present invention, the material for the diaphragm is limited to a material
having a specific elastic modulus of 2600 (Kjl / l0I12) or more, and the reason is that the specific
elastic modulus less than this can not make the resonance point sufficiently high is there.
Moreover, the reason for limiting to chemical vapor deposition as a method of depositing these
substances is that the deposition rate is slow in vacuum deposition-<< problems in cost.
An embodiment of the present invention will be described below based on the drawings. As
shown in FIG. 1 (A), a ring-shaped flange having a radius R16cWL and a plane diameter D25cIIL
is formed by vacuum evaporation depositing pc with a thickness of 0.5 mpic on the inner surface
of dome-shaped substrate 10 made of quartz. 1) form a coating 2 as shown in FIG. 1 ω) 0 Next,
this is placed in a reaction vessel (not shown) and BCl 3 (boron chloride) EndPage: 2-9 2 to 3 of
H 2 gas and H 2 gas Chemical vapor deposition is carried out by heating the substrate 1 at 1050
° C. for 15 minutes by means of an artificial heater in the reaction vessel, and the surface of the
coating 2 is subjected to chemical vapor deposition as shown in FIG. 1 (C). A boron deposit 3 with
a thickness of 60 μm is formed. Next, when the heat is cut and the reaction vessel is cooled, the
thermal expansion coefficient of quartz is 0.58 × 10 and B has a large thermal expansion
coefficient of 8.3 × 10 as compared to quartz, and therefore, the dome-like precipitation of B is
The object 3 is greatly shrunk in the radial direction to be easily peeled off from the substrate 1,
and the dome-shaped diaphragm 4 as shown in FIG. 1) is produced by removing the substrate 1.
In order to investigate the frequency characteristics of the dome-shaped diaphragm 4 obtained in
this manner, the relative sound pressure level was measured with the reference sound pressure
set to 90 dB. The result is as shown by curve A in the graph of FIG. Further, in order to compare
with the present invention, characteristics of the conventional rotary plate made of At alloy
having the same shape are similarly examined, and the result is shown by a curve B in the graph
of FIG. As is apparent from this result, it was confirmed that the diaphragm according to the
method of the present invention is more than twice as deep as the conventional one. As explained
above, according to the method of the present invention, multiple resonance t? It is possible to
obtain a diaphragm without pouring, having a dip in the sound quality and having excellent
frequency characteristics as compared to the conventional diaphragm. The present invention also
manufactures the diaphragm by chemical vapor deposition) Even materials that are difficult to
machine can be easily formed into a dome shape, and their deposition rate is high, and they can
be deposited on the inner surface of a substrate made of quartz and peeled off easily using the
difference in thermal expansion. It is possible to achieve remarkable effects such as being able to
wear well and improve productivity.
4. Brief description of the drawings. FIG. 1 shows an embodiment of the present invention,
illustrating the manufacturing process of the dome-shaped diaphragm, and FIG. 2 shows the
frequency of the dome diaphragm obtained by the method of the present invention. It is a graph
which shows the change of the relative sound pressure level by. 1: Substrate, 2: Coating, S:
Precipitate, 4: Dome-shaped diaphragm. -Applicant agent Attorney Attorney Takehiko Minee °
Fig. 1 (C) (D) 麩 Fig. 2 Supei side (to H2) End Page: 3 (4) Application copy 1 copy 6. Inventors,
patent applicants or agents (1) Inventors' place (2) Agent's address Shibanishi Kubo
Sakuragawacho Minato-ku, Tokyo 17th Mori Building "-4-) JP-A-52 47012 (4) EndPage: 4