FR2493658A1 - SPEAKER MEMBRANE - Google Patents

Abstract

THE INVENTION RELATES TO A SPEAKER MEMBRANE. THE MEMBRANE CONSISTS OF A MOLDED PART OF VULCANIZED RUBBER. IT MAY HAVE A CONICAL, FLAT OR DOME SHAPE, IT MAY OR NOT HAVE STRENGTHENING RIBS, AND OR NOT HAVE DIFFERENT THICKNESSES IN DIFFERENT PARTS. THE INVENTION APPLIES IN PARTICULAR TO HIGH-FIDELITY LOUDSPEAKERS, ESPECIALLY IN BASS SOUNDS.

Description

1 2493658

  The present invention relates to a speaker diaphragm. More particularly, it relates to a membrane that responds faithfully to electrical signals

  input to a loudspeaker, and which may

  faithfully produce the sounds of a source, resulting in the reproduction of powerful bass sounds, without distortion, and clear and consistent sounds in the midrange and treble, which can be used for speakers throughout the range , in the bass,

  in mid-frequency, especially

in the grave.

  So far, paper membranes, made

  of a particular paper that is not treated or coated or impregnated

  born of a resin or a rubber have been widely used in loudspeakers. There are also membranes made of aluminum honeycombs or

of expanded resin.

  It has been accepted in the prior art that all parts of a membrane must move

  together as a piston, at the same phase, and that the

  of partial vibrations indicating that

  The individual parts of a membrane moving at different phases is undesirable. For this reason, in the case of paper membranes, these have

  stiffened by ripples or veins to

  the partial vibrations. In addition, materials

  such as aluminum nesting nests and

  expanded sines that are stiffer than paper have

  adopted in place of the latter.

  Current membranes, which are based on the above mentioned theory, are not necessarily good in response to electrical input signals, resulting in the appearance of distortions. This trend is particularly pronounced in the bass region. Furthermore, when a loudspeaker works

  at high power, reverberations become

  tables so that it is rare to obtain reproduced sounds

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  powerful and clear dudes. In this state of affairs, it is not possible to hope for a faithful reproduction of the sounds of a source, especially the sounds in the bass region when common membranes are used, and the listeners can not rejoice.

  listening to a recording with better

  presence pressures. In the case of membranes in

  Another problem is that

  changes in sound quality under the effect of absorption

humidity are notable.

  An object of the invention is therefore to propose a loudspeaker membrane capable of reproducing the

  sounds from a source with high fidelity while eliminating

  undermining the disadvantages mentioned above.

  Other features and advantages of the

  will be better understood when reading the description of

  The following is a description of several embodiments and with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of an embodiment of a diaphragm according to the invention, the body of which is in the form of 2 and 3 are respectively a plan view and a sectional view of this embodiment, FIGS. 4 and 5 are sections of other embodiments of a cone-shaped body, FIG. is a plan view of a membrane in which the cone-shaped body is provided with ribs, Figure 7 is a section along the line AA of FIG. 6 is a plan view of a membrane in which the cone-shaped body consists of portions whose thicknesses are different from each other, FIG. 9 is a cross-section of FIG. cross section of another embodiment of a membrane in which

3 2493658.

  the cone-shaped body consists of parts of which the. The thicknesses are different, the Figure in which the Figure 11, the Figure in which the ribs, the Figure of FIG. 13, the Figure of FIG. 13, Embodiment d 11 is a plan view of a body membrane in the form of a flat plate, 12 is a section of the membrane of the 13 is a plan view of a body-shaped membrane. flat plate comprises 1.4 is a section along the line BB is a section along the line CC 16 is a planar membrane view of another mode in which the planar plate-shaped body has ribs, Fig. 17 is a section along the line DD of Fig. 16, Fig. 18 is a plan view of another embodiment of a membrane in which the planar plate-shaped body has ribs, Fig. 19 is a section of the diaphragm of FIG. 18 is a plan view of yet another embodiment of a membrane in which the flat plate-like body has ribs, FIG. 21 is a view of the opposite face of the embodiment of FIG. FIG. 20, Figure 22 is a section along line E-E of FIGS. 20 and 21, FIG. 23 is a plan view of a diaphragm in which the flat plate foraminous body consists of portions of different thicknesses, FIG. 24 is a section of the diaphragm of FIG. 23, Fig. 5 is a plan view of a membrane whose body is dome-shaped and

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  Figure 26 is a section of the membrane of the

Fig. 25.

  The invention therefore relates to a membrane of high

  The invention is based on a new theory according to the invention, which consists of a molded piece of vulcanized rubber.

  which the entire membrane does not move ne-

  in the same phase as a piston, going to

  against the preconceived ideas mentioned above.

  A common membrane is made so that the body of this high rigidity membrane comprises

  a flexible edge at its periphery, and that this body

  place like a piston with the same phase as a whole

  ble, thanks to the presence of this edge. In contrast, the membrane according to the invefition is made so that the body is made of vulcanized rubber, with low rigidity and that low rigidity body can vibrate freely without having to move particularly in its entirety to the same phase. In the case of

  the membrane according to the invention, it is therefore not particularly

  it is necessary for the body to have an edge. Under

  this aspect, the membrane according to the invention can be called

  "artificial vocal chords".

  It has been found that the membrane according to the invention

  based on this new theory, presents good

  unexpected response characteristics to electrical signals

  input cues applied to a loudspeaker and faithfully reproduces the sounds of a source, thus producing powerful sounds in the bass region without distortion, and sustained and clear sounds in the midrange and the eagles In particular, the diaphragm according to the invention has excellent damping characteristics and even when high input power in the bass region is applied to the speaker, the reverberations hardly persist, producing clear sounds

  and powerful in the bass region. In addition, the

  brane according to the invention has excellent resistance

  to moisture, unlike paper membranes

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  : there are no changes in the quality of

  sounds under the effect of moisture absorption.

  Another important feature of the mem-

  brane according to the invention is that a loudspeaker which

  door this membrane can deliver a high output power in the bass area, even if its diameter is reduced. In the case of a loudspeaker using a conventional membrane, a diameter of not less than 30 cm, in the ideal case of up to two meters, is necessary to obtain a powerful reproduction

  serious sounds. But a speaker with the mem-

  brane according to the invention, even if its diameter is

  the order of 15 cm, delivers powerful bass sounds

  parable to those obtained with a current loudspeaker with a diameter of o30 cm or more. When the diameter of a

  loudspeaker is reduced, its speaker can be minimally

  which results in a reduction in the price of

  seems and the easy choice of a location or the

speaker can be placed.

  In this respect, the membrane according to the invention

  comes especially for speakers intended for bass sounds. Of course, this membrane also applies to loudspeakers for the entire beach,

  speakers of the medium and treble.

  In addition, in the case of a speaker using the membrane according to the invention, it is unnecessary to fill the loudspeaker enclosure with an absorbent material

  such as fiberglass or felt. It is necessary

  that this advantage results from the specific mode of vibration

  mentioned above of the membrane according to the invention.

  Yet another feature of the membrane according to the invention is that it has a characteristic

  of appearance in addition to the acoustic characteristic

  cited. As indicated above, the mode of

  bursts of a conventional membrane is so monotonous that this membrane is moving primarily forward and

  the back as a piston. On the contrary, the vibratory mode

  of the membrane according to the invention is sufficiently

  plicated so that it can vibrate undulating in addition to the movement forward and backward. These vibrations vary momentarily during the reproduction of a surdisqied recording so that a person who sees the membrane, perceives a sensation that this mem -

  brane offers a facial expression and that this expression

  face change momentarily. In this respect, a

  speaker having a membrane according to the invention is

  preferably used without covering its front face.

  The vulcanized rubber used according to the invention

  This is not particularly limited as regards its physical properties, composition and so on. and it can be chosen appropriately, for example according to the type of speaker on which the membrane is mounted,

  for example a loudspeaker for the whole beach, a loudspeaker

  speaker for bass, mnedium or treble.

  In general, the vulcanized rubber used has a hardness not exceeding 80 measured with a Type A rubber hardness tester, and not less than 15 measured with a Type F rubber hardness tester. , and an impact elasticity that is not less than 40e. It is preferable to use a vulcanized rubber with a tensile strength of 0.1 to 200 kg / cm 2, an elongation of 200 to 1000% and a specific gravity of 0.8 to 1.5 in addition to

aforementioned physical properties.

  In the following, the rubber hardness tester of Tycrc A is a device provided in JIS K 6301-1969. The F-type rubber hardness tester is an apparatus manufactured by Kobunshi Keiki Manufacturing Co., Ltd., which is used primarily for hardness measurements of expanded rubber, urethane foam and the like. . Although the vulcanized rubber used is the invention, it is a rubber that is full of the hardness of some of these rubbers.

  vulcanized is very weak and can not be

  the type A hardness measuring device uses

  to measure the hardness of solid rubbers.

2493658

  For this purpose, the lower limit of rubber hardness

  vulcanized used according to the invention is defined by the

  their measured hardness with the Type F measuring device. An intermediate hardness between the measuring range of the Type A rubber hardness tester and that of the Type F hardness measuring device. can be measured with a Type C rubber hardness tester. The latter as used is intended by the Japan Standard Society of Rubber Industry SRIS-001- to measure these intermediate hardnesses between the measuring ranges of the devices. type A and

  The type C measuring device is used primarily

  to measure the hardness of sponges, rubber

  soft bunch and others. The device manufactured by Kobunshi

  Seiki blanufacturing Co., Ltd., is used as an

  The hardness of the vulcanized rubber used according to the invention can be determined by any of the hardness measuring devices of type A, type B and

  type F, if the measurement is possible with one of these

  REILS. But if a hardness, as measured with the

  If the measuring pressure of type A is not greater than 10, it is preferable to measure it with the type C device or

  type F because a measurement error with the device

  Type A is important. Similarly, if a hardness measured with the type C apparatus is not greater than 1, it is preferable to measure it with the type F apparatus. Similarly, if a hardness measured with the apparatus type C is not less than 99, it is preferable to measure it with the Type A apparatus. In a similar way, if a hardness measured with the

  measurement of type F is not less than 99, it is preferred

  to measure it with the Type C measuring device or

  the measuring device type A. The hardness values measured

  With the apparatus of type A, the apparatus of type C and the apparatus of type F are hereinafter referred to respectively as hardness A, hardness C and hardness FLa composition of the rubber from which is obtained the vulcanized rubber mentioned above. above is also particularly limited, comprising for example (A) 100 parts by weight, as subsequently, of a rubber component, (B) O to 2000 parts of a filler and (C) 0 to 2000 parts of softening agent (considering that the case one the quantity of the component (B) and that of the

  component (C) are null excepted).

  Examples of the rubber component (A) are polynorbonene, natural rubber, isoprene rubber, chloroprene rubber, styrene-butadiene rubber,

  butadiene rubber, butyl rubber, ethyl rubber and

  ethylene-propylene, ethylene-propylene rubber--

  diene, nitrile rubber, acrylic rubber, urethane rubber, chlorinated polyethylene,

  chlorosulphonated polyethylene, epichloro

  hydrine, polysulfide rubber, silicone rubber and others. Rubbers regenerated from

  of these constituents (for example, rubber powder

  rubber or the like) are also included. These

  The stituents of the catouchouc can be in solid form (powder, platelets, blocks, leaves, etc.) or in the form of liquid (liquid rubber, latex, etc.). In addition, the above constituents can be used alone or

  mix two or more types of them.

  As a component charge (B), different types of charges can be used, such as white charge, black charge, amber charge, and charge.

  the fillers being obtained by different vulcanizing

  vegetable oils, including linseed oil, rapeseed oil, soybean oil, sesame oil, oil

  teat and beaver oil with sulfur or chlorine

  sulfur. These fillers can be used alone in the mixture. The filler obtained by vulcanizing oil

  rapeseed is particularly favorable.

  The softening agent as component (C)

  takes oils, plasticizers and other agents with softening activity. For oils it is possible to use one of the filling oils for

  generally used rubber (such as

  softening, a processing oil, etc.) such as aromatic oils, naphtha oils, paraffin oils, vegetable oils and animal oils and

  other. The vegetable and animal oils mentioned above

  above include beaver oil, rapeseed oil, linseed oil, whale oil, fish oil and others. As plasticizers it is possible to use one

  those with high levels of resilience such as

  the plasticizers generally used for

  rubbers. It should be noted that dibutyl phthalate, phthalate

  dioctylate, dioctyl sebacate, etc. As

  other softening agents, it is necessary to mention

  liquid bucks. The softening agents mentioned below

  can be used alone or in a mixture of two

  oa several types. In general, an oil alone or a

  The mixture of an oil and a plasticizer is used pre-

ference.

  To the rubber composition mentioned above

  it is necessary to add different additives, generally

  used, for example, fillers such as black

  carbon dioxide and zinc oxide, dyes, lubricants,

  such as stearic acid, and antioxidants.

  For the vulcanization of the rubber composition

  above, any of the vulcanization systems

  usual use may be appropriate. Sulfur vulcanization

  and without sulfur may be suitable. The vulcanization conditions

  tion, etc., are not particularly limited and

  usual conditions are adopted.

  In general, vulcanized rubber of great

  It is used to produce a membrane for the reproduction of high tones and a vulcanized rubber for

  hardness is used to produce a membrane

  tinA: e when playing bass sounds. In general, a

2493658.

  vulcanized rubber with a hardness of not less than 20 in hardness A is used for the medium and

  and a vulcanized rubber of a hardness that does not

  It does not pass 30, preferably more than 20 A hardness is used for serious. According to the invention, it has been found that a vulcanized couch with a hardness which is between the hardness A not exceeding 30, preferably not exceeding 20, and

  a hardness F of not less than 15, particularly

  not less than 30 and an impact resistance of not less than 50%, preferably 60 to 95% if appropriate, with additionally a tensile strength of 100 kg / cm2, 0.1 to 100 kg / cm 2, especially 1 to 50 kg / cm and an elongation of 100 to 1000 $, particularly 200 to 1000%, and a specific gravity of 0.8 to 1.3, of Preferably from 0.89 to 1.1 is suitable for speaker diaphragms for bass, midrange and all-round loudspeakers, particularly bass. Membranes

  made of this specific rubber are particularly suitable

  to give a high fidelity of bass sounds.

  The vulcanized rubber specified above is a

  new material that was not known until now.

  In other words, in the case of vulcanized rubbers

  those with a hardness not exceeding

  have an impact elasticity less than 40 and those with an impact elasticity of not less than 40,

  a hardness A greater than 30. It is well known that the elasticity

  The impact sensitivity of vulcanized rubber decreases with its hardness. The physical properties of the specific vulcanized rubber mentioned above, that is to say a hardness A which does not exceed 30, particularly that which does not exceed with an impact elasticity of not less than 50%, particularly from 60 to 95%. , are quite

  outside of previous common concepts.

  Vulcanized rubber with properties

  particular physical characteristics mentioned above may be

  held by vulcanizing a rubber composition which

  takes (A) 100 parts of a rubber component, (B) 11 to 2000 parts, preferably 20 to 1500 parts, more preferably 100 to 1500 parts of a filler and (C) to 2000 parts, preferably 200 to 1500 parts of a

  softening agent. This rubber composition obtains

  maintaining by adding large amounts of a filler and a softening agent to a rubber component,

  constitutes a new composition. Only in vul-

  It is possible to obtain a particular vulcanized rubber having a hardness of not more than 30, especially not more than 20, of hardness A, and not less than 15, particularly not less than 15. at 30 hardness F and with an impact elasticity which is not inferior

  at 50a, particularly 60 to 95Co.

  In the rubber composition above a predominantly rubber constituent

  polynorbonene is preferred as component (A). Lors-

  a mixture of polynorbonene and another constituent

  of rubber is used, it is desirable that the

  portion of polynorbonene is not less than 505

  (percents by weight, as well as subsequently), preferably

  not less than 65c.

  A typical formula of a rubber composition

  Specific bunch mentioned above, taking into account sulfur vulcanization as an example, is as follows: Components (Parts) Rubber Constituent 100 Charge 20 to 1,500 Softener 200 to 1,500 Filling 1 to 200 Antioxidant 0.5 to 6 Sulfur 0.5 to 10 Vulcanization Accelerator 1 to 20 The shape of the membrane according to the invention is not

  particularly limited, and the shapes of the membranes

  rants can be adopted. Preferred forms are as follows: FIG. 1 is a perspective view of an embodiment of a membrane according to the invention, FIG.

  is a plan view and FIG. 3 a cross section.

  The reference 1 designates the body of a conical membrane, the reference 2 an assembly part connected directly to the outer peripheria of the body 1 without the interposition of a

  edge between them, and the reference 3 designates an opening.

  The body 1 is fixed on the carcass of a loudspeaker by the fixing part 2. A moving coil is fixed on the inner periphery 4 of the body 1. The opening 3 is

closed by a hood.

  The conical shape of the body 1 is not limited to a rectilinear cone as shown in FIGS. 1 to 3, and other forms such as a hyperbolic or exponential cone shown in section in FIG. 4, and a parabolic cone shown in section in FIG. 5 may be suitable. The planar shape (the shape seen from the front, the same being true thereafter) of the body 1 is not limited to a circular shape shown in FIG. 2 and other shapes such as elliptical and polygonal

  (including polygons such as the triangle, the tetra-

  gone, the pentagon, the hexagon, and so on) as well

  regular polygons or variants can

come.

  The body 1 may have ribs. These nerves

  vures fulfill the function of reinforcing elements

  when the body 1 is thin. But the ribs do not

  not only reinforcing elements but

  also contribute to the sound quality of the reproduced sounds.

  For example, they improve the amor-

  invest-. The ribs are for example provided in the manner shown in FIG. 16 (plan view) and Fig. 7 (runs along the line A-A of Fig. 6). Ribs

  shown in Figs. 6 and 7 are radial ribs

  the 5a and a concentric circular rib 5b.

  When the planar shape of the body 1 differs from a circle, the concentric circular rib 5b can be

13 2493658

  transformed into correspondence with the shape of the body 1.

  The concentric circular rib 5b includes these transformed shapes. Radial line 5a or circular rib

  concentric 5b can be deleted. The number, the

  sition, etc. ribs 5a and 5b can be decided at will depending on the rigidity and the diameter of the body 1, and the desired sound quality. The ribs 5a and 5b may be provided at the front of the body 1 or at the rear,

  or on both surfaces. In another mode of reassessment

  The ribs 5a are provided at the front and the rib b at the rear. An embodiment contrary to this can also be adopted. The arrangement of the ribs is

  not limited to radial or circular arrangements

  centric, as mentioned above, and others

  various positions such as a starred or

Grid may be suitable.

  In general, the thickness of the body 1 is uniform (insofar as the ribs are not taken into account, the same applies later) but this body 1 may have different thicknesses in its parts.

  individual. For example, the body 1 is made of

  that it consists of three parts. la, lb and lc which have different thicknesses from each other as

  shown in FIG. 8 (plan view) and FIG. 9 (in section).

  In this embodiment, it is possible to make the parts la, lb and lc with different thicknesses to respond to different frequency bands. Therefore, the membrane according to the invention is preferable

  especially for a speaker throughout the range.

  According to Figs 8 and 9, the body 1 is thicker in

  the innermost and thinner part in the

  part lb and again in part lc, towards the outer periphery

On the contrary, body 1 may be thicker in the outermost part 1c, and

  thin from part lb to part la, in the direction

  tion of the inner periphery of the body 1, as shown in FIG. 10 (in section).) Steps are formed on the front face of the body 1 when the individual parts

  of the body 1 have different thicknesses as the

  Figs. 8 and 9. On the contrary, the steps can be formed at the rear of the body 1 and in this case, the front face is flat. In addition, steps can be formed on both surfaces. In addition, the thickness of the body 1 can vary gradually so that no step is formed. (When the individual parts of

  body 1 change in thickness concentrically, nerves

  circumferences may be provided at the boundaries between the individual parts as shown in Figure 10, the interferences between parts la, lb and lc being

  reduced and the frequency bands covered by the

  la, lb and lc are clearly separated from each other.

other.

  The characteristic of the membrane according to the invention

  tion is that it is particularly unnecessary to provide an edge. However, the membrane according to the invention can

  be provided with an edge 6 as shown in Figure 9.

  The shape of the edge 6 is not particularly limited and different shapes such as a circular arc, a U-shaped and a V-shaped section, as shown

  FIG. 9 and a shaped bellows formed

  binding several edges of the above forms may be suitable.

  FIG. 11 is a plan view of another embodiment of a membrane according to the invention and the

  Fig. 12 is a section of this embodiment. The reference

  7 denotes a body in the form of a flat plate and the reference 8 an attachment part connected directly to the outer periphery of the body 7 without interposition.

  dOne edge between them. The body 7 is fixed on a cone of

  in the fixing part 8. According to FIGS.

  and 12, the thickness of the fixing portion S is greater than

  than the body 7, but its thickness could be equal to or less than that of the body 7 when this

last in itself is thick.

  The planar shape of the flat plate body 7 is not limited to a circular shape as shown in FIG. 11, and other forms such as elliptical and

  polygonal can be adopted.

  The body 7 in the shape of a flat plate may comprise

  ribs in the same way as the conical body

  For example, radial ribs 5a and a concentric circular rib 5b may be provided as shown in FIG. Fig. 13 (plan view), Fig. 14 (section B-B of Fig. 13), and 15 (C-C section of the

  Fig. 13). The radial ribs 5a o. the circular rib

  Concentric 5b can be removed. Number, layout, etc. ribs 5a and 5b can be chosen at will taking into account the rigidity and

  body diameter 7, and the desired sound quality.

  The ribs 5a and 5b may be provided on the front face of the body 7 or on the rear face, (or on both

  In another embodiment, the nerves

  vures 5a are provided on the front face and the rib 5b on the rear face. An embodiment contrary to

  it can also be adopted. Different modes of

  in which the body 7 comprises ribs are shown in FIGS. 16 to 18, 19 and 20 to 22. The ribs of FIG. 16 (plan view) and FIG. 17 (D-D section of Fig. 16) simply consist of radial ribs 5a. The ribs of FIG. 18

  (plan view) and FIG. 19 (sectional view) does not

  take only concentric circular ribs 5b.

  The ribs of FIG. 20 (plan view) of FIG. Fig. 21 (plan view of opposite side to that of Fig. 20) and Fig. 22 (section E-E of Figs 20 and 21) consist of radial ribs 5a provided on a surface of the body 7 and concentric circular ribs 7b

on the opposite surface.

  The flat plate-shaped body 7 can be made in such a way that its thickness differs in its individual parts in the same way as the body

  1. For example, the body 7 is made in such a way that

  re it consists of three parts 7a, 71 and 7c whose 1 6 the thicknesses are different, the others as shown in the ig. 23 (plan view) and FIG. 24 (in section). In this case, the body 7 may be thinner in its innermost part 7a and thicker in the direction of the part 7h to the part 7c in the direction

  the outer periphery of the body 7, as shown in

  Trent] es] ig. 23 '24. On the other hand, the body 7 may be thinner at its outermost part 7c and thicken from the part 7b to the part 7a in the direction of the center of the body 7. Steps are formed on the front face of the body 7 because of the different thicknesses of the individual parts of this body as

  Fig. 23 and 24. On the other hand, the bleachers can be

  on the rear face of the body 7 and in this case, the front face is flat. However, steps can be formed on both surfaces. In addition, the thickness of the body 7 can change gradually, so that no step is formed. When the individual parts of the body 7 change thickness, concentric circular ribs 5b can be provided at the boundaries between

  individual parts with different thicknesses

  as shown in Figures 23 and 24, thus reducing

  if the interference between the parts 7a, 7b and 7c, and the frequency bands supported by the parts 7a,

  7b and 7c are clearly separated from each other.

  The body 7 in the form of a flat plate comprises

  also an edge 6 in the same way as the body co-

  Figure 1, for example, as shown in Figures: 16 and

  17. FIG. 25 is a plan view of another embodiment of

  of a membrane according to the invention and FIG. 26

  is a cut. Reference 9 designates a body in form

me dome.

  The p-shaped form of the dome-shaped body 9

  is not limited to a circular form such as

  Figs. 25 and 26 and others such as

  ticks and vines may be adopted. In the same way as for the conical body 1 and the flat body 7, the body 9 may also have ribs,

  changes in thickness or have an edge.

  In the membrane according to the invention, the thickness of the body is preferably of the order of 3 to 2 mm, preferably of the order of 0.5 to 1.5 mm. Edge may not be expected when body hardness A does not exceed 30. do it is desirable to provide an edge when

the hardness A of the body exceeds D 0.

  The membrane according to the invention is obtained by

  lantizing and vulcanizing a rubber composition such as

  mentioned above, in the form described above.

  above. The way can be the same as the usual way

  to produce molded pieces of vulcanized rubber. For example, a rubber composition is directly vulcanized under pressure in a mold of a given configuration. Alternatively, a non-vulcanized sheet is prepared by calender or extrusion molding, followed by vulcanization.

  under pressurei. Injection molding is also possible

  sible. It is desirable that the ribs are formed at the same time in the mold, but they can be shaped by cutting after vulcanization. In addition, the ribs can be made independently of the body of the membrane and glued to this body by means of a

suitable adhesive or others.

  The membrane according to the invention will now be

written by examples.

Examples 1 to 3

  Loudspeaker membranes were produced using the rubber compositions shown in Table 1. Example 1, Example 2 and Example 3 were directed to the production of a loudspeaker membrane for bass, a speaker for I

  medium and a speaker for treble respectively.

Table 1

  Rubber composition (in parts) Constituents Examples

1 2 3

Norsorex 150 iA (Note 1) 250 - -

Nipol SBR 1712 (Note 2) - 137.5 -

  Natural rubber - - 100 Load DOG F 10 (Note 3) 270 320 30

Sunthene 255 (Note 4) 700 22 -

  Carbon FEF 25 65 80 Zinc oxide 5 5 5 Stearic acid 1 I 1 Antioxidant DDA (Note 5) 2 2 2 Suntight S (Note 6) 2 2 2 Soubr 2 2 2 Sunceller CZ (Note 7) 12 3 2 Note 1 : Polynorborene (Norsorex, average molecular weight not less than 2 x 106) elongated with 150 parts

  of naphthalene oil for 100 parts of poly-

  norborene, released by Nippon Zeon Co., Ltd. (Norsorex: brand name) Note 2: Elongated styrene-butadiene rubber with 37.5

  parts of a high aromatic oil for every 100

  made of rubber, manufactured by Nippon Zeon Co., Ltd. Note 3: Amber sulfur charge manufactured by D.O.G. Deutsche Oelfabrick Gesellschaft fir Chem. Eirz. m.b.H. & Co.

  Note 4: Naphthenic oil manufactured by Japan Sunoil Co.Ltd.

  Note 5: Diphenylamine oxidant manufactured by Bayer A.G.

  Note 6: Microcrystalline wax manufactured by Seiko Kagaku Fabushiki Kaisha Note 7: N-cyclohexyl-2-benzothiazyl sulfenamide manufactured

by Sanhin Kagaku Kabushiki Kaisha.

  The rubber constituent was first washed at

  about 600C, then kneaded with other constittrants at

  yen of a 13anbury mixer and then a roll, and finally

  sheets of a thickness of the order of 2 to 3 mm. A disc

  that was cut from the sheet and vulcanized by a pressurized machine to obtain a molded piece under a pressure of 15 x 10 pA at 155 ° C, for 20 minutes to obtain membranes having the following forms: Membrane of Example 1 ( serious) Formed: Fig. 13 to 15 Overall diameter of the membrane: 236 mm Thickness of the corpz 7: 0,8 mm Radial ribs 5a: Number: 16 Length: 42 mm Width: 2 mm Height: 0,8 min Circular concentric ribs 5b: Number: 1 Width : 6 mm Height: 0, 8 mm Fixing part 8: Width: 10 mm Thickness: 1.6 mm Membrane of Example 2 (medium) Shape: Fig. 13 to 15 Total diameter of the membrane: 100 mm Thickness of the body 7: Radial ribs 5a: Number: 16 Length: 18 mm Width: 2 mm Height: 0.7 mm Circular concentric ribs 5b: Number: d 1 Width: 3 mm Height: 0.7 mm Fixing part S: I. argeur 5 mm Thickness: 1.4 mn -embrane of Example 3 (acute) Elm: Fig. 16 and 17 Total diameter of the membrane: 80 mim Body 7: Diameter (] e diameter of the membrane to the ex-

  ception of the edge 6 and the fixing part

  8): 50 mm Thickness: 0.7 mm Radial ribs. 5a: Number: 12 Length: 12 mm Width: 1.5 mm Height: 0.7 mm Rim 6: Shape: Ur section Thickness: 0.7 mm Fixing part8: Width: 5 mm Thickness: 1, 4 mm

  Test pieces were cut from the mem-

  obtained branes and different physical properties have

  were measured on these test pieces. The results appear

  Table 2. Elasticity measures at

  shocks of tensile strength and inductive elongation

  Table 2 was carried out according to standard

JIS K 6301-1969.

Table 2

3o Physical Properties Examples

1 2 3

  Hardness A (degrees) 7 30 70 Impact elasticity (%) 73 57 46 Tensile strength (kg / cm 2) 20 25 122 Elongation () 372 245 Specific weight 1, 004 1,057 1,176 2 1 The membranes obtained in the examples 1, 2 and 3 have been fixed on top-beaders found on the market, rather than their flat-plate shaped members to form respectively a loudspeaker for the bass, a loudspeaker for the medium and a loudspeaker for the medium. the eagles. The resulting speakers have been placed in a

  market to form a system of high-

  speakers with three channels. No absorbent material was used in this case. Using these speakers, a listening test was conducted. As a comparison, the same listening experience was carried out with a system of

  three-channel speakers found on the m-ch

  taking a bass speaker with a conical paper diaphragm with a diameter of 30 cr, a loudspeaker for the medium with a conical paper membrane with a diameter of 4 cm and a loudspeaker for the eaves with

  a conical paper membrane with a diameter of 5 cm.

  (1) Reproduction Equipment Main Pre-amplifier: AU-D) 907 (manufactured by Sansui Electric Co., Ltd.) Platinum: DP-4OF (manufactured by Nippon Columbia Co.Ltd.) Cassette: V-15 Type 3 ( manufactured by Shure Brothers, Inc) (2) Ermplacement Deaf House (Equipped with air conditioning and fan) Floor: Vinyl floors (with underlying layer of mortar) Ceiling: Non-flammable (no opening) pl sound absorption) Inner walls: plywood (3) Test method

  A group of four trained auditors was in-

  To listen to the following recording and to classify it according to the following parameters: Test recording: Title and recording: F1.arnenco Fever (:, iiller *) Reisel Sounrc: Corp. in USA Performers: '? he Phil ] aarnonia {ungarica Program:] lorona (tradiGionnel) IParameters and evaluation standards (a) Power of severe sounds Excel] ant: Your power was very rich 3tonon: the power was rich Ordinary: Your power was Door (b) Béverb6- excel ration]] ente: No reverb Good: little reverb Normal: Considerable reverb (c) Distortions of bass Excellent: No distortion Good: low distortion 1.5 Ordinary: di-torsion cnnsidable (d) Presence Impressions Excellent: Presence very rich Good: Presence rich Ordinary: Presence poor The results of listening tests appear in Table 3. The four listeners gave the same ratings.

Table 3

  Parameters: Speakers Parameters: Invention Comparative Power of bass sounds excellent ordinary Ordinary excellent reverb Sound distortion severe bass excellent ordinary Presence excellent ordinary As is clear from Fig. 3, the

  The membranes according to the invention have given excellent results.

  slow with all parameters, compared with common napier membranes. An important point was the

  reproduction of delicate sounds, such as

  3, when the thin plate of the floor was struck by small impacts, the sounds produced when the palm of a hand which was placed in contact with the skin of a drum.

  is separated, and sounds that are produced in the cor-

  vocals tremble. These delicate sounds could absolutely not be reproduced by the usual loudspeakers and could only be heard live.

  For the first time, it was possible to repro-

  in the manner indicated above by a built-in

  comprising the membrane according to the invention.

Examples 4 to 6

  Using rubber compositions indicative of

  in Table 4, loudspeaker diaphragms

  were produced in the same way as in the examples

  ples 1 to 3; Examples 4 and 5 were oriented towards

  production of a membrane for serious sounds. They form

  Examples of the membranes of Examples 4 and 5 were the same as those of the membrane of Example 1. Example 6 was directed to the production of a membrane for the medium; The shape of the membrane of Example 6 was the

  same as that of the membrane of Example 2 with the excep-

tion that an edge 6 was provided.

  Physical properties of membranes obtained

  in Examples 4 to 6 are shown in Table 5.

Table 4

  Composition of rubber (in parts)

Examples

Constituents: 4 5 4 5t

Norsorex 150 NA 250 -

Nipol SUT 1712 137,5 - -

  Nipol II1 2200 (Note) - - 100 Load DOG F 10 270 230 220 Sunthene 255 400 22 Snhn 5

Dioctyl phthalate - 50 -

Carbon FEF - 50 85

Carbon SRF 40 - -

Carbon ".T 45 - -

  Zinc Oxide 5 5 j Stearic Acid 1 1 1 Excluding Constituents

6

  Antioxidant uDA 2 to 2 Suntight S 2 1 2 Soufer 2 2.5 2 Sunceller CZ 4 O 4 Note: Isoprene rubber made by Nippon Zeon Co. abl] water 5 x. Hardness () Elasticity RFsist.on the Allon- Weight

  N A C F to shocks traction spec.

($) (kg / cm2) (CI)

4 18 - - 60 21 364 1.016

- 11 73 6 6.5 387 0.977

  Using the respective membranes obtained in Examples 4 and 5, two types of bass speakers were produced. The respective loudspeakers were used instead of those having the membrane of Example 1 in the previously obtained three-channel loudspeaker system. The resulting system gave the same excellent results in the bass sounds as those obtained

  with the previous three-channel system.

  Using the membrane obtained in Example 6, a loudspeaker for the medium was produced and it was used instead of the one with the diaphragm of the example, = 2 in the three-speaker system. previously obtained channels. The resulting system gave the same excellent sonic results on average as those obtained

by the previous svrtème.

  Of course, various modifications can be

  provided by those skilled in the art to the above-described

  written and illustrated as non-restrictive examples

  without departing from the scope of the invention.

  IR VIr NDI CA'r ON'c 1 -! EmbFrana loudspeaker, characterized in that it consists of a piece mou.lée (1, 7, 9) a

vulcanized rubber é.

  2 - Membrane according to claim 1, characterized

  in that the vulcanized part has a hardness in the range not exceeding 80 ° measured with a type A rubber hardness tester, and which is not less than 15 measured with a hardness tester of type F rubber, with elasticity at

  shocks not less than 40% 0.

  3 - Membrane according to claim 2, characterized

  in that the hardness is not greater than 300,

  with Type A rubber hardness tester.

  4. Membrane according to claim 3, characterized

  in that the hardness is not greater than 20 measured with the Type A rubber hardness tester, and is not less than 30 measured with the Type F rubber hardness tester, elasticity

  shocks not being less than 50c.

  Membrane according to claim 3 or 4, characterized in that the vulcanized molding is a single piece.

  vulcanized rubber mold of a composition comprising

  (A) 100 parts by weight of a rubber component

  rubber, (13) five to 2000 parts by weight of a load and

  (C) 20 to 2000 parts by weight of a softening agent.

  6 - Membrane according to claim 5, characterized

  in that the proportion of component (B) is between 100 and 15nO parts by weight and the proportion of component (C) is comorized between 200 to 1500 parts by weight.

  7 - Membrane according to claim 5, characterized

  that constituent (A) consists mainly of

in polynorhornene.

  8 - Membrane according to claim 1, wherein

  in that the body (1) of the member is conical.

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