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Specification 1, title of the invention "
Method of manufacturing diaphragm for electrodynamic type Sbee 'force
3. Detailed description of the invention French patent 1269138, first additional patent 87555,
French patent 7107225, a static (including vibrational electrical energy) and a static (blowing
mechanical energy) An electric speaker is disclosed. The transducer acts as a driver and the
turner acts as an element to vibrate the layer of ambient air. The transformer comprises a
plurality of permanent magnets of equal or unequal length, the magnets being arranged in
parallel layers defining parallel passages, in which magnetic fields circulate. The bladder or
lightweight vibrating diaphragm is made of a low density material, preferably expanded
polystyrene. A plurality of grooves and ribs are formed on the inward side of the diaphragm
facing the transducer, and the ribs extend longitudinally into at least a portion of the parallel
passages of the transducer. A conductive band is attached to the rib which receives an electrical
current corresponding to the sound to be transmitted, said band being in the form of a
serpentine zig-zag, which is named in the aforementioned patent as a brief (greek). In the abovementioned patent, the hollow has high fidelity without distortion, the hollow is moving with the
correct parallel relation, improving the response characteristics at each frequency, especially at
low frequencies, eliminating harmful vibration. ,It is an object. However, in practice these goals
have not always been achieved. The problem solved by the invention lies in the fact that a
satisfactory solution has not been achieved in terms of the surface condition of the diaphragm in
the air-diaphragm contact area. One object of the present invention is to improve the acoustical
properties of an electrodynamic loudspeaker by improving the surface condition of the expanded
polystyrene diaphragm. A conventional electrodynamic loudspeaker comprises a flat foam
polystyrene diaphragm which is driven by a transducer having a band bent in a briefs shape
across the rear face of the bladder and has a conductive brief structure bonded to the diaphragm
It includes the tissue of a magnetic member formed by a series of magnets arranged in the same
direction in facing relationship. The theoretical effect of this type is that the diaphragms move in
a parallel relationship, the diaphragms are equally acted on at each point on the whole surface,
and the generated signals are in phase. The piston action of this device, i.e. moving in parallel, is
not practically achieved.
Since the diaphragm is manufactured by cutting from a material, the balance relation of internal
stress of the material is lost, and as a result of lack of uniformity of thickness, rigidity and density
become equal (· area is generated). These defects and the inhomogeneity of the magnetic field of
the transducer distort the conductive band. Since distortion in the band can not be prevented
because the rigidity of the diaphragm is insufficient, local deformation occurs on the surface of
the diaphragm, distortion occurs in the generated sound, and local phase difference occurs. If the
rigidity of the diaphragm is insufficient, the size is uneven, and the surface hardness is too high, a
hard and metallic sound is generated, and a phenomenon called coloring occurs. The coloration
of the sound generated from the bubble is mainly due to the properties of the material (specific
gravity, Young's modulus), in particular the properties of the surface of the diaphragm which
causes it to move in contact with air (ie the aforementioned air-diaphragm contact area). Based
on the surface condition, foreign matter which acts only on the skin (the aforementioned contact
area) and which may change the properties, density, solidity, etc. of the material constituting the
diaphragm is added. There is no EndPage: 2 It needs to be softened by treatment. The method
according to the invention makes use of the residual amount of water vapor which remains
immediately after the foaming of the polystyrene and which is confined within the blank when
the diaphragm is molded into a ribbed substantially final shape. After the blank has been
removed from the mold, it is condensed by lowering the temperature to move it as water to the
surface with the ribs and grooves of the blank, and by significantly freezing the blank of the
diaphragm, within the thin surface area of the diaphragm. And the steps of exposing the soft
surface directly below the surface area by removing the surface area by an appropriate
processing operation. In a particularly advantageous embodiment of the invention, the foam
polystyrene blank is in the form of a block, the two opposing surfaces of which respectively
define the concavo-convex surfaces of two identical diaphragms, which are oppositely facing one
another and Thereafter, the block is cut from the block and the middle part of the block is
discarded after cutting, but in the form of steam in the early stages of the manufacturing process,
acting as a supply reservoir for the water when water is injected into the mold. Do. Aspects and
effects of the present invention other than those described above will be made clear by the
following description with reference to the accompanying drawings. In the embodiment shown in
FIG. 1 (•, the molded blank integrally comprises the first diaphragm 1, the second diaphragm 2
and the middle central portion 3 ° C.).
In FIG. 2, the central portion 3 is cut and discarded as will be described later, and only two
diaphragms after grinding are shown. % 'M Coating Surfaces of Both Diaphragms The surface is
produced by the hydrothermal-temperature treatment according to the invention. The method
according to the invention comprises the step of molding an integral foam of polystyrene foam. A
known method for the foaming of this material is to simultaneously jet high pressure steam and
polystyrene into a mold of near "desired" shape. It should be noted that the direction of force
when the material conforms to the shape of the mold determines the final structure of the
diaphragm. This results in increased rigidity and improved dimensional stability when the block
is finalized for a given density of material. In the final machining for this, a significantly smaller
amount of material is removed. Surface treatment is performed in the next step. When the
formed blank is injected from the mold with the water vapor and removed from the mold, a
proportion of water vapor remains trapped in the material. The first step of the surface treatment
step moves this water toward the surface of the pro and the mold, and under the influence of the
polished surface of the mold, down the relatively watertightly formed skin, this movement being
It is achieved by condensation of the water vapor by lowering the temperature to 5-6 ° C. for
several hours. The thickness of the epidermis 4 is 10 minutes of fermentation. The central
portion 3 acts as a water supply reservoir, the thickness of which is predetermined, making it
possible to control the second stage process described below. The second stage of the process is
to significantly freeze the blank at -18 ° C to -20 ° C for several hours. Immediately below the
skin of the blank, the confined and condensed water freezes to increase its volume and the
narrow area 5 or 6 below the skin 4 due to the temperature drop and the material becoming
brittle at that temperature. Produces fine fracture in the material to be formed. The thickness of
this area is for example from the bottom of the groove. In the third step of the process, after
drying, the skin 4 is removed by grinding to expose the surface of the blank having a final shape
and the softened state adjacent to the skin. In FIG. 1, a cut is made along the plane I8, this
position being determined by the amount of water confined in the central part 3. This size is
determined by conducting a test in advance. The amount of water supplied to control the desired
thickness of the area to be treated is determined by the thickness of the central portion 3. In
summary, polystyrene is foamed in the area not in contact with the mold, and a water-thin film is
formed on the surface by welding.
Grinding produces a cotton-like or fuzzy matte surface. The fibrous tissue of polystyrene is
broken in the area of contact between the diaphragm and air. In the case of the diaphragm not
treated by the method according to the invention, the EndPage: 3 texture has a glossy surface,
which is significantly detrimental to the sound transmission. The surface state of the epidermis 4
is a hard skin having poor acoustic characteristics. Therefore, the epidermis 4 needs to be
removed. Tests have shown that removal of the epidermis according to the invention results in an
acoustically complete surface. In addition, the combination of the humidity and temperature
processing according to the present invention converts the tissue at the beginning of the blank
(at the time of generation) about the area of the distance consisting of the bottom of the six
grooves of the diaphragm, By cutting the central portion 3 of the diaphragm from the two parts
(i.e. the diaphragms) 1 and 2 before use, the internal structure of the diaphragm is desirably
transformed to the cutting area shown in plane 1, I + Chemical characteristics are significantly
improved. The serrated outer surface of the diaphragm starts with the removal of the skin 4 to
obtain this excellent property. In practice, the blank is allowed to dry as it is. Blanks are stored
for several weeks to several months when drying is not artificially performed. Next, i.e. the
diaphragm is ground as it is in one piece, just before it is used, after which the tapping surface 1.
(the overall stiffness is effective for the mechanical skin removal operation). [Do the cutting work
according to [1. The diaphragm produced according to the invention is equivalent both on the
surface with grooves and ribs and on the cutting plane 5 = I 'plane. The two diaprams produced
in this way are equivalent and have perfect acoustical properties over their entire surface.
4. Brief description of the drawings FIGS. 1 and 2 are explanatory views illustrating the method
for producing a diaphragm for an electrodynamic speaker according to the present invention,
and FIG. 1 is a perspective view showing a molded integral block. FIG. 2 is a perspective view
showing two diaphragms manufactured by grinding and cutting the pros of FIG. ], 2: Diaphragm
(diaphragm) 3: Central part 4: Epidermis Attorney Patent attorney Junnosuke Nakamura