WO2007043837A1 - Acoustic diaphragm and speakers having the same - Google Patents
Acoustic diaphragm and speakers having the same Download PDFInfo
- Publication number
- WO2007043837A1 WO2007043837A1 PCT/KR2006/004139 KR2006004139W WO2007043837A1 WO 2007043837 A1 WO2007043837 A1 WO 2007043837A1 KR 2006004139 W KR2006004139 W KR 2006004139W WO 2007043837 A1 WO2007043837 A1 WO 2007043837A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- acoustic diaphragm
- carbon nanotubes
- graphite nanofibers
- acoustic
- diaphragm according
- Prior art date
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 150
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 93
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 85
- 239000010439 graphite Substances 0.000 claims abstract description 58
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 58
- 239000002121 nanofiber Substances 0.000 claims abstract description 57
- 239000012744 reinforcing agent Substances 0.000 claims abstract description 29
- 239000000463 material Substances 0.000 claims description 60
- -1 polyethylene Polymers 0.000 claims description 22
- 239000004743 Polypropylene Substances 0.000 claims description 17
- 229920001155 polypropylene Polymers 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 16
- 239000004697 Polyetherimide Substances 0.000 claims description 10
- 239000004698 Polyethylene Substances 0.000 claims description 10
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 10
- 239000000835 fiber Substances 0.000 claims description 10
- 229920001601 polyetherimide Polymers 0.000 claims description 10
- 229920000573 polyethylene Polymers 0.000 claims description 10
- 239000004094 surface-active agent Substances 0.000 claims description 10
- 229910052719 titanium Inorganic materials 0.000 claims description 10
- 239000010936 titanium Substances 0.000 claims description 10
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 8
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 8
- 239000002109 single walled nanotube Substances 0.000 claims description 8
- 239000000919 ceramic Substances 0.000 claims description 4
- 239000002048 multi walled nanotube Substances 0.000 claims description 4
- 235000021355 Stearic acid Nutrition 0.000 claims description 3
- 229910052783 alkali metal Inorganic materials 0.000 claims description 3
- 150000001340 alkali metals Chemical class 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052790 beryllium Inorganic materials 0.000 claims description 3
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 229910052801 chlorine Inorganic materials 0.000 claims description 3
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 3
- 229930195729 fatty acid Natural products 0.000 claims description 3
- 239000000194 fatty acid Substances 0.000 claims description 3
- 150000004665 fatty acids Chemical class 0.000 claims description 3
- 229910052731 fluorine Inorganic materials 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims description 3
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 230000003014 reinforcing effect Effects 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000008117 stearic acid Substances 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 229910052723 transition metal Inorganic materials 0.000 claims description 3
- 150000003623 transition metal compounds Chemical class 0.000 claims description 3
- 150000003624 transition metals Chemical class 0.000 claims description 3
- 230000000704 physical effect Effects 0.000 abstract description 22
- 238000000034 method Methods 0.000 description 13
- 229910003460 diamond Inorganic materials 0.000 description 7
- 239000010432 diamond Substances 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 239000011301 petroleum pitch Substances 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 229910052594 sapphire Inorganic materials 0.000 description 4
- 239000010980 sapphire Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000002131 composite material Substances 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000010295 mobile communication Methods 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000008240 homogeneous mixture Substances 0.000 description 2
- 239000003562 lightweight material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920006231 aramid fiber Polymers 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R7/00—Diaphragms for electromechanical transducers; Cones
- H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R11/00—Transducers of moving-armature or moving-core type
- H04R11/02—Loudspeakers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
- H04R2231/001—Moulding aspects of diaphragm or surround
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
- H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
Definitions
- the present invention relates to an acoustic diaphragm and speakers having the acoustic diaphragm. More specifically, the present invention relates to an acoustic diaphragm comprising carbon nanotubes (CNTs) or graphite nanofibers (GNFs) as reinforcing agents, and speakers having the acoustic diaphragm.
- CNTs carbon nanotubes
- GNFs graphite nanofibers
- Speakers are electrical components that convert electrical energy into mechanical sound energy and are currently utilized in a wide variety of applications, including telephones, mobile communication terminals, computers, television (TV) sets, cassettes, sound devices and automobiles.
- Speaker systems generally consist of a diaphragm, a damper, a permanent magnet, an encloser, and other elements. Of these elements, the diaphragm has the greatest effect on the sound quality of the speaker systems.
- a dilatational wave occurs due to the variation in the air pressure between the front and the rear of a diaphragm and is transduced into an audible sound wave.
- the sound quality of speakers largely depends on the vibrational mode of diaphragms used in the speakers.
- the performance required for speakers is that electrical input signals to the speakers must be fully reproduced. It is preferable for speakers to reproduce sounds of high and constant pressure over a broad frequency arnge from low-frequency sounds to high-frequency sounds to hing-frequency sounds.
- Frequency characteristic curves of speakers are required to have a broad frequency range from the lowest resonant frequency (Fa: the limit frequency for the reproduction of low-frequency sounds) to a higher resonant frequency (Fb: a substantial limit frequency for the reproduction of high-frequency sounds), a high sound pressure, and flat peaks with few irregularities.
- diaphragms In order to achieve the above requirements of speakers, diaphragms must satisfy the following three characteristics.
- diaphragms must have a high elastic modulus.
- High resonant frequency is proportional to the sound speed, which is proportional to the square root of elastic modulus. Based on these relationships, when the lowest resonant frequency is constant, the frequency band for the reproduction of sounds can be broadened depending on the increased elastic modulus of diaphragms.
- diaphragms must have a high internal loss. Irregular peaks found in frequency characteristic curves are due to the occurrence of a number of sharp resonances in vibration systems. Therefore, high internal loss of diaphragms makes resonance peaks regular. That is, in speakers using an acoustic diaphragm with a high internal loss, only a desired sound frequency is vibrated by the acoustic diaphragm and no unwanted vibration occurs. As a result, the occurrence of unnecessary noise or reverberation is reduced and high-frequency peaks can be lowered, so that the original sounds can be effectively produced without being changed.
- diaphragms must have a light weight (or a low density). It is desirable that vibration systems including a diaphragm be as light as possible in order to obtain a high sound pressure from an input signal having specific energy. In addition, it is preferable that diaphragms be made of a lightweight material having a high Young's modulus in order to increase the longitudinal wave propagating velocity or sound wave propagating velocity.
- diaphragms To satisfy the aforementioned requirements associated with the physical properties of diaphragms, many materials for diaphragms have been developed. Examples of such materials for diaphragms include carbon fibers and aramid fibers, which have a high elastic modulus, and polypropylene resins, which have a high internal loss.
- diaphragms made of titanium coated with diamond-like carbon can achieve superior sound quality, they have the problems of complicated procedure of production and relatively high price of the material, which limit the use of diamond as a material for the diaphragms despite the realization of superior sound quality by the diaphragms.
- diaphragms having a thickness not less than 10 D are coated with sapphire- or diamond-like carbon to improve the strength of the diaphragms.
- the coating of diaphragms having a thickness not greater than 10 D with sapphire- or diamond-like carbon causes the hardening of the diaphragms, thus making it impossible to achieve desired sound quality of speakers.
- a reduction in the thickness of diaphragms in view of miniaturization of the diaphragms leads to enhanced elasticity of the diaphragms but causes the problem of low strength of the diaphragms.
- the problem is solved by coating diaphragms with sapphire or diamond.
- coating of diaphragms having a small thickness (e.g., 10 D or less) with sapphire or diamond causes hardening of the diaphragms.
- the present invention has been made in view of the problems, and it is one object of the present invention to provide an acoustic diaphragm comprising highly dispersible carbon nanotubes (CNTs) or graphite nanofibers (GNFs) that has excellent physical properties in terms of elasticity, internal loss, strength and weight, can achieve superior sound quality, and can be widely used in not only general speakers, including micro, small and large speakers, but also in piezoelectric speakers.
- CNTs carbon nanotubes
- GMFs graphite nanofibers
- an acoustic diaphragm for converting electrical signals into mechanical signals to produce sounds wherein the acoustic diaphragm comprises carbon nanotubes or graphite nanofibers as reinforcing agents.
- the carbon nanotubes or graphite nanofibers may be included or dispersed in the acoustic diaphragm to function as reinforcing agents.
- the carbon nanotubes or graphite nanofibers may be coated on the surface of the acoustic diaphragm to function as reinforcing agents.
- the carbon nanotubes or graphite nanofibers may be coated on the central portion of the acoustic diaphragm.
- the acoustic diaphragm may comprise a polymeric material as a major material.
- the polymeric material may be polyethylene (PE), polypropylene (PP), polyetherimide
- the acoustic diaphragm may comprise a pulp or a mixture thereof with a fiber as a major material.
- the acoustic diaphragm may comprise a metal selected from aluminum, titanium and beryllium as a major material.
- the acoustic diaphragm may comprise a ceramic as a major material.
- the carbon nanotubes or graphite nanofibers may be single-walled carbon nanotubes, multi-walled carbon nanotubes, graphite nanofibers, or a mixture thereof.
- the carbon nanotubes or graphite nanofibers may have a shape selected from straight, helical, branched shapes and mixed shapes thereof, or may be a mixture of carbon nanotubes or graphite nanofibers having different shapes.
- the carbon nanotubes or graphite nanofibers may include at least one material selected from the group consisting of H, B, N, O, F, Si, P, S, Cl, transition metals, transition metal compounds, and alkali metals.
- the acoustic diaphragm may comprise a surfactant, stearic acid or a fatty acid to disperse the carbon nanotubes or graphite nanofibers.
- the acoustic diaphragm may comprise 0.1 to 50% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm.
- the acoustic diaphragm may comprise 0.1 to 30% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm.
- the acoustic diaphragm may comprise 0.1 to 20% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm.
- speakers comprising the acoustic diaphragm.
- the speakers may be micro speakers or piezoelectric speakers.
- FlG. 1 is a cross-sectional view of a micro speaker having an acoustic diaphragm of the present invention.
- FlG. 2 is a cross-sectional view of a piezoelectric speaker having an acoustic diaphragm of the present invention.
- Carbon nanotubes have a structure in which each carbon atom is bonded to adjacent three carbon atoms to form hexagonal rings and sheets of the hexagonal rings arranged in a honeycomb configuration are rolled to form cylindrical tubes.
- Carbon nanotubes have a diameter of several tens of angstroms (A) to several tens of nanometers (nm) and a length of several tens to several thousands of times more than the diameter. Carbon nanotubes exhibit superior thermal, mechanical and electrical properties due to their inherent shape and chemical bonding. For these advantages, a number of researches have been conducted on the synthesis of carbon nanotubes. The utilization of the advantageous properties of carbon nanotubes is expected to overcome technical limitations which have remained unsolved in the art, leading to the development of many novel products, and to provide existing products with new characteristics which have been not observed in the products.
- composites of carbon nanotubes and polymeric materials can achieve desired physical properties, such as tensile strength, electrical properties and chemical properties.
- the carbon nanotube composites are expected to greatly contribute to improve disadvantages of the polymeric materials in terms of tensile strength, elasticity, electrical properties and durability (Erik T. Thostenson, Zhifeng Ren, Tsu- Wei Chou, Composites Science and Technology 61 (2001) 1899-1912).
- R. Andrews, Y. Chen et al. reported that single-walled nanotubes can be used as reinforcing agents of petroleum pitch fibers. Specifically, they demonstrated that the tensile strength, elastic modulus and electrical conductivity of petroleum pitch fibers are greatly enhanced by the use of 1% by weight of single-walled nanotubes as reinforcing agents in the petroleum pitch fibers. They also reported that the tensile strength, elastic modulus and electrical conductivity of petroleum pitch fibers with 5% loading of single-walled nanotubes as reinforcing agents are enhanced by 90%, 150% and 340% respectively.
- the carbon nanotubes (CNTs) used in the present invention have a structure in which graphite sheets are rolled into tubes, exhibit a high mechanical strength due to the strong covalent bonding between carbon atoms, and exhibit superior mechanical properties due to their high Young's modulus and high aspect ratio. Further, since the carbon nanotubes (CNTs) are composed of carbon atoms, they are light in weight but exhibit excellent physical properties. Thus, the acoustic diaphragm of the present invention using the carbon nanotubes as reinforcing agents has more advantageous properties than improvements expected in the mechanical properties of acoustic diaphragms using other reinforcing agents.
- carbon nanotubes (or graphite nanofibers) used in the acoustic diaphragm of the present invention can be vibrated at a high frequency due to their light weight and good elasticity.
- the carbon nanotubes (or graphite nanofibers) have high mechanical strength despite their small size or high length- to-radius ratio(aspect ratio), their original shape is maintained so that the carbon nanotubes (or graphite nanofibers) can be vibrated at a desired high frequency.
- the inclusion (coating) of carbon nanotubes as reinforcing agents in a major material for an acoustic diaphragm enables considerable improvements in physical properties, such as elastic modulus, internal loss and density, required for the acoustic diaphragm.
- the major material for the acoustic diaphragm of the present invention is not limited so long as the carbon nanotubes or graphite nanofibers can be included or dispersed in the major material for the acoustic diaphragm or coated on the surface of the acoustic diaphragm.
- suitable major materials for the acoustic diaphragm of the present invention include: pulps and mixtures thereof with fibers; reinforced fibers, such as carbon fibers; resins, such as polyethylene (PE), polypropylene (PP), polyetherimide (PEI), polyethylene terephthalate (PET) and mixtures thereof; metals, such as aluminum, titanium and beryllium; ceramics; and mixtures thereof.
- reinforced fibers such as carbon fibers
- resins such as polyethylene (PE), polypropylene (PP), polyetherimide (PEI), polyethylene terephthalate (PET) and mixtures thereof
- metals such as aluminum, titanium and beryllium
- ceramics such as aluminum, titanium and beryllium
- Carbon nanotubes or graphite nanofibers can be used as reinforcing agents to reinforce the major material for the acoustic diaphragm.
- Examples of suitable carbon nanotubes (CNTs) or graphite nanofibers (GNFs) that can be used in the present invention include, but are not limited to, single- walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), graphite nanofibers (GNFs), and mixtures and composites thereof.
- SWNTs single- walled carbon nanotubes
- MWNTs multi-walled carbon nanotubes
- GNFs graphite nanofibers
- mixtures and composites thereof There is no particular restriction as to the shape of the carbon nanotubes (CNTs) or graphite nanofibers (GNFs) so long as the CNTs or GNFs contribute to improve desired physical properties.
- the carbon nanotubes or graphite nanofibers may have various shapes, such as helical, straight and branched shapes.
- the carbon nanotubes or graphite nanofibers may include at least one material selected from the group consisting of H, B, N, O, F, Si, P, S, Cl, transition metals, transition metal compounds and alkali metals, or may react with these materials.
- the carbon nanotubes or graphite nanofibers used in the present invention may be produced by a method known in the art, such as arc discharge, laser vaporization, plasma enhanced chemical vapor deposition (PECVD), thermal chemical vapor deposition or vapor phase growth.
- PECVD plasma enhanced chemical vapor deposition
- thermal chemical vapor deposition thermal chemical vapor deposition or vapor phase growth.
- a surfactant may be used to homogeneously disperse the carbon nanotubes (CNTs) or graphite nanofibers (GNFs) in the acoustic diaphragm.
- Any surfactant that serves to homogeneously distribute the carbon nanotubes or graphite nanofibers and enhance the binding force to improve the physical properties of the acoustic diaphragm may be used, and examples thereof include, but are not particularly limited to, cationic, anionoic and nonionic surfactants.
- a stearic acid or a fatty acid may also be used.
- the carbon nanotubes or graphite nanofibers may be coated on the surface of the acoustic diaphragm to function as reinforcing agents. At this time, the carbon nanotubes or graphite nanofibers may be coated on the central portion of the acoustic diaphragm to enhance the strength of the central portion.
- the acoustic diaphragm of the present invention may comprise 0.1 to 50% by weight, preferably 0.1 to 30% by weight and more preferably 0.1 to 20% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the polymeric material.
- carbon nanotubes were dispersed in a polymeric material for an acoustic diaphragm by the following procedure. First, carbon nanotubes were dispersed in a solvent. Then, a polymeric material was dissolved in the carbon nanotube solution. Thereafter, the solvent was evaporated or removed to obtain a state in which the carbon nanotubes as reinforcing agents were dispersed in the polymeric material.
- An acoustic diaphragm was produced using polypropylene and carbon nanotubes as reinforcing agents dispersed in the polypropylene.
- the carbon nanotubes were used in an amount of 1% by weight, based on the weight of the polypropylene.
- the carbon nanotubes were single-walled carbon nanotubes (SWNTs) having an average diameter of 1 nm and a length of 1 ⁇ m.
- Example 1 The procedure of Example 1 was repeated, except that a surfactant was further used to enhance the degree of dispersion of the carbon nanotubes without changing the conditions employed and the contents of the materials used in Example 1.
- polyoxyethylene-8-lauryl ether CH -(CH ) (OCH CH ) OCH
- C12EO8 CH (hereinafter, referred to simply as "C12EO8") was used.
- C12EO8 was homogeneously dissolved in the solvent.
- 50 D of the carbon nanotubes was added to the C12EO8 solution.
- 5g of polypropylene was slowly added dropwise thereto with violent stirring.
- the resulting mixture was stirred for about 30 minutes.
- the homogeneous mixture was poured into a mold having a diameter of 20 mm and a thickness of 1 mm. The mold was placed in an oven at the temperature of 80°C and allowed to stand for about one day to evaporate the solvent and stabilize the carbon nanotubes within the polymeric material.
- the polymeric material was detached from the mold to produce a polypropylene acoustic diaphragm using the carbon nanotubes as reinforcing agents.
- Example 2 produced using the surfactant, when compared to in the acoustic diaphragm (Example 1) produced without using any surfactant, as observed by an electronic microscope.
- Example 2 except that the kind and the amount of carbon nanotubes or graphite nanofibers were varied as indicated in Table 1.
- the changes in the elasticity of the samples were measured according to the kind of the polymeric materials used. The results are shown in Table 1.
- the increases in elasticity of the samples were evaluated on the basis of increases in the elasticity of the same polymer samples without using any carbon nanotubes or graphite nanofibers.
- the SWNTs (single wall nanotubes) used herein had an average diameter of 1 nm and a length of 1 ⁇ m.
- the graphite nanofibers (GNFs) used herein were herringbone type graphite nanofibers having an average diameter of 10 nm and a length of 1 D.
- Carbon nanotubes or graphite nanofibers have a high mechanical strength due to the strong covalent bonding between carbon atoms and a high Young's modulus.
- carbon nanotubes or graphite nanofibers have a lower specific weight than the polymeric materials. Therefore, the use of carbon nanotubes or graphite nanofibers in acoustic diaphragms leads to considerable improvements in physical properties, such as strength, and a reduction in weight, thus making it possible to achieve superior sound quality.
- Carbon nanotubes dispersed in a material, particularly a polymeric material, for an acoustic diaphragm can serve to greatly improve the physical properties, such as elastic modulus, internal loss and density, required for the acoustic diaphragm.
- acoustic reproducers e.g., speakers
- system speakers for use in high-fidelity (Hi-Fi) audio systems including a woofer, a midrange and a tweeter for covering a predetermined frequency band
- general speakers for covering the entire frequency band by a single unit micro speakers that are ultra-light in weight and ultra-slim in thickness designed to be used micro-camcorders, portable audio recorders (walkmans), personal digital assistants (PDAs), notebook computers, mobile communication terminals, headphones, cellular phones, telephones, radiotelegraphs, etc., receivers for use in mobile communication terminals, earphones whose part is inserted into the user's ear, and buzzers for receiving only a specific frequency band.
- Hi-Fi high-fidelity
- component systems e.g., component systems
- micro speakers that are ultra-light in weight and ultra-slim in thickness designed to be used micro-camcorders
- PDAs personal digital assistants
- notebook computers mobile communication terminals, headphones, cellular phones, telephones, radio
- the acoustic diaphragm of the present invention can be used in the above- mentioned speakers and is produced so as to have optimum physical properties according to the performance required for the speakers.
- a magnet 14 and a magnet plate 15 are disposed within a yoke 12, and a voice coil 13 surrounds the periphery of the magnet 14 and magnet plate 15.
- a driving signal is generated in a state in which a diaphragm 16 is connected to both ends (i.e. a cathode and an anode) of the voice coil 13, the diaphragm is vibrated to produce a sound.
- a non- alternating (direct current (DC)) magnetic flux is generated in a magnetic circuit passing through the magnet plate 15 via the magnet 14, and an alternating (alternating current (AC)) rotating magnetic flux is generated in the voice coil 13 capable of moving upward and downward.
- the non-alternating magnetic flux responds to the alternating rotating magnetic flux according to Fleming's left-hand rule to cause attractive and repulsive forces.
- the diaphragm 16 and the voice coil 13 are vibrated upward and downward to produce a sound corresponding to the driving signal.
- the thickness of the diaphragm according the present invention which comprises carbon nanotubes or graphite nanofibers as reinforcing agents, is reduced, the elasticity of the diaphragm is improved without any deterioration in strength.
- FlG. 2 shows the structure of a piezoelectric speaker (a flat panel speaker).
- a diaphragm 21 used in the piezoelectric speaker 20 is in the form of a thin plate and is required to be highly durable and lightweight.
- the diaphragm 21 of the present invention is lightweight, is highly elastic and has a high mechanical strength as compared to conventional diaphragms. Therefore, the piezoelectric speaker 20 having the diaphragm 21 of the present invention can advantageously achieve superior sound quality.
- the acoustic diaphragm of the present invention can be widely used in micro speakers, piezoelectric speakers, and small, medium and large speakers, regardless of the shape and structure of the speakers.
- the acoustic diaphragm of the present invention since the acoustic diaphragm of the present invention has excellent physical properties in terms of elastic modulus, internal loss, strength and weight, it can effectively achieve superior sound quality and a high output in a particular frequency band as well as in a broad frequency band.
- the acoustic diaphragm of the present invention can be widely used in not only general speakers, including micro, small, medium and large speakers, but also in piezoelectric speakers (flat panel speakers).
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Multimedia (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Chemical & Material Sciences (AREA)
- Nanotechnology (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
Abstract
Disclosed herein is an acoustic diaphragm for converting electrical signals into mechanical signals to produce sounds. The acoustic diaphragm comprises carbon nanotubes or graphite nanofibers as reinforcing agents. Preferably, the carbon nanotubes or graphite nanofibers are included or dispersed in the acoustic diaphragm or coated on the surface of the acoustic diaphragm. Since the acoustic diaphragm has excellent physical properties in terms of elastic modulus, internal loss, strength and density, it can effectively achieve superior sound quality and a high output in a particular frequency band as well as in a broad frequency band.
Description
Description
ACOUSTIC DIAPHRAGM AND SPEAKERS HAVING THE
SAME
Technical Field
[1] The present invention relates to an acoustic diaphragm and speakers having the acoustic diaphragm. More specifically, the present invention relates to an acoustic diaphragm comprising carbon nanotubes (CNTs) or graphite nanofibers (GNFs) as reinforcing agents, and speakers having the acoustic diaphragm.
[2]
Background Art
[3] Speakers are electrical components that convert electrical energy into mechanical sound energy and are currently utilized in a wide variety of applications, including telephones, mobile communication terminals, computers, television (TV) sets, cassettes, sound devices and automobiles.
[4] Speaker systems generally consist of a diaphragm, a damper, a permanent magnet, an encloser, and other elements. Of these elements, the diaphragm has the greatest effect on the sound quality of the speaker systems.
[5] A dilatational wave occurs due to the variation in the air pressure between the front and the rear of a diaphragm and is transduced into an audible sound wave. The sound quality of speakers largely depends on the vibrational mode of diaphragms used in the speakers. The performance required for speakers is that electrical input signals to the speakers must be fully reproduced. It is preferable for speakers to reproduce sounds of high and constant pressure over a broad frequency arnge from low-frequency sounds to high-frequency sounds to hing-frequency sounds.
[6] Frequency characteristic curves of speakers are required to have a broad frequency range from the lowest resonant frequency (Fa: the limit frequency for the reproduction of low-frequency sounds) to a higher resonant frequency (Fb: a substantial limit frequency for the reproduction of high-frequency sounds), a high sound pressure, and flat peaks with few irregularities.
[7]
[8] In order to achieve the above requirements of speakers, diaphragms must satisfy the following three characteristics.
[9] Firstly, diaphragms must have a high elastic modulus. High resonant frequency is proportional to the sound speed, which is proportional to the square root of elastic modulus. Based on these relationships, when the lowest resonant frequency is constant, the frequency band for the reproduction of sounds can be broadened depending on the
increased elastic modulus of diaphragms.
[10]
[11] Secondly, diaphragms must have a high internal loss. Irregular peaks found in frequency characteristic curves are due to the occurrence of a number of sharp resonances in vibration systems. Therefore, high internal loss of diaphragms makes resonance peaks regular. That is, in speakers using an acoustic diaphragm with a high internal loss, only a desired sound frequency is vibrated by the acoustic diaphragm and no unwanted vibration occurs. As a result, the occurrence of unnecessary noise or reverberation is reduced and high-frequency peaks can be lowered, so that the original sounds can be effectively produced without being changed.
[12]
[13] Thirdly, diaphragms must have a light weight (or a low density). It is desirable that vibration systems including a diaphragm be as light as possible in order to obtain a high sound pressure from an input signal having specific energy. In addition, it is preferable that diaphragms be made of a lightweight material having a high Young's modulus in order to increase the longitudinal wave propagating velocity or sound wave propagating velocity.
[14] It is ideal to use lightweight materials having a high elastic modulus and a high internal loss to produce diaphragms, but these requirements are incompatible with each other. Therefore, to find a material for diaphragms whose requirements are in harmony with each other is a prerequisite for the manufacture of speakers with superior sound quality.
[15] To satisfy the aforementioned requirements associated with the physical properties of diaphragms, many materials for diaphragms have been developed. Examples of such materials for diaphragms include carbon fibers and aramid fibers, which have a high elastic modulus, and polypropylene resins, which have a high internal loss.
[16] As the elastic modulus of a diaphragm increases, the internal loss of the diaphragm decreases but the density of the diaphragm increases. In addition, as the internal loss of a diaphragm increases, the elastic modulus of the diaphragm decreases but the density of the diaphragm increases.
[17] The conventional materials that have widely been used to produce acoustic diaphragms satisfy the aforementioned physical properties to some extent. However, increasing demand for speakers capable of producing high-quality sounds has led to a demand for the acoustic diaphragms having a higher elastic modulus and a higher internal loss than conventional diaphragms.
[18] Therefore, an important task for the production of ideal acoustic diaphragms is to keep an optimum balance between the physical properties.
[19] In this regard, various materials, such as pulp, silk, polyamide, polypropylene,
polyethylene (PE), polyetherimide (PEI) and ceramic, have been widely used as materials for acoustic diaphragms. Titanium is currently being used as a material for acoustic diaphragms. In particular, titanium coated with diamond-like carbon is used to increase the quality of high-frequency sounds.
[20] The use of titanium diaphragms causes a lowering of the sound pressure in a high- frequency sound band, at which the balance of sounds is kept. In contrast, diaphragms made of diamond-coated titanium markedly raise the sound pressure.
[21] For example, the sound pressure of titanium diaphragms drops rapidly in a high frequency band of 19 kHz or more. In contrast, diamond-coated diaphragms have twice to three times longer life and more exclusive physical properties than those of titanium diaphragms. Due to these advantages, there is an increasing demand for diamond- coated diaphragms in household electrical appliances, including videocassette recorders (VCRs), headphones and stereos.
[22] Although diaphragms made of titanium coated with diamond-like carbon can achieve superior sound quality, they have the problems of complicated procedure of production and relatively high price of the material, which limit the use of diamond as a material for the diaphragms despite the realization of superior sound quality by the diaphragms.
[23]
[24] In the meanwhile, a reduction in the thickness of diaphragms in view of improvement in the sound quality of speakers causes the deterioration in the strength of the diaphragms. Accordingly, diaphragms having a thickness not less than 10 D are coated with sapphire- or diamond-like carbon to improve the strength of the diaphragms. However, the coating of diaphragms having a thickness not greater than 10 D with sapphire- or diamond-like carbon causes the hardening of the diaphragms, thus making it impossible to achieve desired sound quality of speakers.
[25] As the output of conventional micro speakers increases, the movement of diaphragms becomes larger, thus causing the problem of serious divisional vibration arising from distortion of the diaphragms. In attempts to solve the problem, many methods have been employed, for example, a method for reinforcing a diaphragm by introducing a corrugated shape to the diaphragm to prevent the diaphragm from being broken and a method for increasing the thickness of a diaphragm to improve the stiffness of the diaphragm.
[26] Although these methods ensure prevention of distortion and breaking of diaphragms, they cause an increase in the amplitude of low-frequency sounds at a high output of 0.5 watts or higher, and as a result, poor touch and unsatisfactory vibration (movement) of the diaphragms are caused, leading to the raise of the lowest resonant frequency of the diaphragms. This raised lowest resonant frequency makes it difficult
to reproduce low-frequency sounds.
[27] A reduction in the thickness of diaphragms in view of miniaturization of the diaphragms leads to enhanced elasticity of the diaphragms but causes the problem of low strength of the diaphragms. The problem is solved by coating diaphragms with sapphire or diamond. However, coating of diaphragms having a small thickness (e.g., 10 D or less) with sapphire or diamond causes hardening of the diaphragms.
[28] There is thus a need for the ultra-small acoustic diaphragm having enhanced elasticity and high strength that can be used in micro speakers.
[29] Further, there is a need for the acoustic diaphragm having improved physical properties in terms of elasticity, strength and internal loss that can be used in general small and large speakers and piezoelectric speakers (flat panel speakers) as well as micro speakers. Disclosure of Invention Technical Problem
[30] The present invention has been made in view of the problems, and it is one object of the present invention to provide an acoustic diaphragm comprising highly dispersible carbon nanotubes (CNTs) or graphite nanofibers (GNFs) that has excellent physical properties in terms of elasticity, internal loss, strength and weight, can achieve superior sound quality, and can be widely used in not only general speakers, including micro, small and large speakers, but also in piezoelectric speakers.
[31] It is another object of the present invention to provide speakers having the acoustic diaphragm.
[32]
Technical Solution
[33] In accordance with one aspect of the present invention for achieving the above objects, there is provided an acoustic diaphragm for converting electrical signals into mechanical signals to produce sounds wherein the acoustic diaphragm comprises carbon nanotubes or graphite nanofibers as reinforcing agents.
[34] In a preferred embodiment of the present invention, the carbon nanotubes or graphite nanofibers may be included or dispersed in the acoustic diaphragm to function as reinforcing agents.
[35] In a further preferred embodiment of the present invention, the carbon nanotubes or graphite nanofibers may be coated on the surface of the acoustic diaphragm to function as reinforcing agents. In this preferred embodiment, the carbon nanotubes or graphite nanofibers may be coated on the central portion of the acoustic diaphragm.
[36] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise a polymeric material as a major material. In this preferred embodiment,
the polymeric material may be polyethylene (PE), polypropylene (PP), polyetherimide
(PEI), polyethylene terephthalate (PET), or a mixture thereof. [37] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise a pulp or a mixture thereof with a fiber as a major material. [38] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise a metal selected from aluminum, titanium and beryllium as a major material. [39] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise a ceramic as a major material. [40] In another preferred embodiment of the present invention, the carbon nanotubes or graphite nanofibers may be single-walled carbon nanotubes, multi-walled carbon nanotubes, graphite nanofibers, or a mixture thereof. [41] In another preferred embodiment of the present invention, the carbon nanotubes or graphite nanofibers may have a shape selected from straight, helical, branched shapes and mixed shapes thereof, or may be a mixture of carbon nanotubes or graphite nanofibers having different shapes. [42] In another preferred embodiment of the present invention, the carbon nanotubes or graphite nanofibers may include at least one material selected from the group consisting of H, B, N, O, F, Si, P, S, Cl, transition metals, transition metal compounds, and alkali metals. [43] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise a surfactant, stearic acid or a fatty acid to disperse the carbon nanotubes or graphite nanofibers. [44] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise 0.1 to 50% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm. [45] In another preferred embodiment of the present invention, the acoustic diaphragm may comprise 0.1 to 30% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm. [46] In yet another preferred embodiment of the present invention, the acoustic diaphragm may comprise 0.1 to 20% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the major material for the acoustic diaphragm. [47] In accordance with another aspect of the present invention, there are provided speakers comprising the acoustic diaphragm. [48] In a preferred embodiment of the present invention, the speakers may be micro speakers or piezoelectric speakers. [49]
Brief Description of the Drawings
[50] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
[51] FlG. 1 is a cross-sectional view of a micro speaker having an acoustic diaphragm of the present invention; and
[52] FlG. 2 is a cross-sectional view of a piezoelectric speaker having an acoustic diaphragm of the present invention.
[53]
Best Mode for Carrying Out the Invention
[54] The present invention will now be described in greater detail.
[55] Carbon nanotubes (CNTs) have a structure in which each carbon atom is bonded to adjacent three carbon atoms to form hexagonal rings and sheets of the hexagonal rings arranged in a honeycomb configuration are rolled to form cylindrical tubes.
[56] Carbon nanotubes have a diameter of several tens of angstroms (A) to several tens of nanometers (nm) and a length of several tens to several thousands of times more than the diameter. Carbon nanotubes exhibit superior thermal, mechanical and electrical properties due to their inherent shape and chemical bonding. For these advantages, a number of researches have been conducted on the synthesis of carbon nanotubes. The utilization of the advantageous properties of carbon nanotubes is expected to overcome technical limitations which have remained unsolved in the art, leading to the development of many novel products, and to provide existing products with new characteristics which have been not observed in the products.
[57] In particular, composites of carbon nanotubes and polymeric materials can achieve desired physical properties, such as tensile strength, electrical properties and chemical properties. The carbon nanotube composites are expected to greatly contribute to improve disadvantages of the polymeric materials in terms of tensile strength, elasticity, electrical properties and durability (Erik T. Thostenson, Zhifeng Ren, Tsu- Wei Chou, Composites Science and Technology 61 (2001) 1899-1912).
[58] A number of conventional studies associated with the use of conventional carbon nanotubes have been done to reinforce polymers. For example, it was reported that the addition of 1% by weight of carbon nanotubes to polystyrene results in 25% and 36-42% increases in tensile stress and elastic modulus, respectively (Qian D, Dickey EC, Andrews R, Rantell T. Applied Physics Letters 2000; 76 (20): 2868-2870).
[59] R. Andrews, Y. Chen et al. reported that single-walled nanotubes can be used as reinforcing agents of petroleum pitch fibers. Specifically, they demonstrated that the tensile strength, elastic modulus and electrical conductivity of petroleum pitch fibers
are greatly enhanced by the use of 1% by weight of single-walled nanotubes as reinforcing agents in the petroleum pitch fibers. They also reported that the tensile strength, elastic modulus and electrical conductivity of petroleum pitch fibers with 5% loading of single-walled nanotubes as reinforcing agents are enhanced by 90%, 150% and 340% respectively. Particularly, they anticipated that the binding force between petroleum pitch fibers and carbon nanotubes will be enhanced due to the same aromaticity of the petroleum pitch fibers and the carbon nanotubes (R. Andrews, et al., Applied Physics Letters 75 (1999) 1329-1331).
[60] From the results of these studies, including those of studies that have previously been conducted, it is obvious that the use of carbon nanotubes as reinforcing agents of polymeric materials results in a further improvement in the physical properties of the polymeric materials. Therefore, the results can be applied to the production of acoustic diaphragms having superior performance to that of conventional acoustic diaphragms using polymeric materials alone.
[61] The carbon nanotubes (CNTs) used in the present invention have a structure in which graphite sheets are rolled into tubes, exhibit a high mechanical strength due to the strong covalent bonding between carbon atoms, and exhibit superior mechanical properties due to their high Young's modulus and high aspect ratio. Further, since the carbon nanotubes (CNTs) are composed of carbon atoms, they are light in weight but exhibit excellent physical properties. Thus, the acoustic diaphragm of the present invention using the carbon nanotubes as reinforcing agents has more advantageous properties than improvements expected in the mechanical properties of acoustic diaphragms using other reinforcing agents.
[62] In other words, carbon nanotubes (or graphite nanofibers) used in the acoustic diaphragm of the present invention can be vibrated at a high frequency due to their light weight and good elasticity. In addition, since the carbon nanotubes (or graphite nanofibers) have high mechanical strength despite their small size or high length- to-radius ratio(aspect ratio), their original shape is maintained so that the carbon nanotubes (or graphite nanofibers) can be vibrated at a desired high frequency.
[63] Particularly, the inclusion (coating) of carbon nanotubes as reinforcing agents in a major material for an acoustic diaphragm enables considerable improvements in physical properties, such as elastic modulus, internal loss and density, required for the acoustic diaphragm.
[64] The major material for the acoustic diaphragm of the present invention is not limited so long as the carbon nanotubes or graphite nanofibers can be included or dispersed in the major material for the acoustic diaphragm or coated on the surface of the acoustic diaphragm.
[65] Examples of suitable major materials for the acoustic diaphragm of the present
invention include: pulps and mixtures thereof with fibers; reinforced fibers, such as carbon fibers; resins, such as polyethylene (PE), polypropylene (PP), polyetherimide (PEI), polyethylene terephthalate (PET) and mixtures thereof; metals, such as aluminum, titanium and beryllium; ceramics; and mixtures thereof.
[66] Carbon nanotubes or graphite nanofibers can be used as reinforcing agents to reinforce the major material for the acoustic diaphragm.
[67] Examples of suitable carbon nanotubes (CNTs) or graphite nanofibers (GNFs) that can be used in the present invention include, but are not limited to, single- walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs), graphite nanofibers (GNFs), and mixtures and composites thereof. There is no particular restriction as to the shape of the carbon nanotubes (CNTs) or graphite nanofibers (GNFs) so long as the CNTs or GNFs contribute to improve desired physical properties. The carbon nanotubes or graphite nanofibers may have various shapes, such as helical, straight and branched shapes.
[68] To achieve desired physical properties or affinity of the acoustic diaphragm according to the present invention, the carbon nanotubes or graphite nanofibers may include at least one material selected from the group consisting of H, B, N, O, F, Si, P, S, Cl, transition metals, transition metal compounds and alkali metals, or may react with these materials.
[69] The carbon nanotubes or graphite nanofibers used in the present invention may be produced by a method known in the art, such as arc discharge, laser vaporization, plasma enhanced chemical vapor deposition (PECVD), thermal chemical vapor deposition or vapor phase growth.
[70] Uniform dispersion of the carbon nanotubes or graphite nanofibers in the acoustic diaphragm of the present invention is effective in exhibiting inherent physical properties of the carbon nanotubes or graphite nanofibers.
[71] For example, a surfactant may be used to homogeneously disperse the carbon nanotubes (CNTs) or graphite nanofibers (GNFs) in the acoustic diaphragm. Any surfactant that serves to homogeneously distribute the carbon nanotubes or graphite nanofibers and enhance the binding force to improve the physical properties of the acoustic diaphragm may be used, and examples thereof include, but are not particularly limited to, cationic, anionoic and nonionic surfactants. A stearic acid or a fatty acid may also be used.
[72] The carbon nanotubes or graphite nanofibers may be coated on the surface of the acoustic diaphragm to function as reinforcing agents. At this time, the carbon nanotubes or graphite nanofibers may be coated on the central portion of the acoustic diaphragm to enhance the strength of the central portion.
[73] The acoustic diaphragm of the present invention may comprise 0.1 to 50% by
weight, preferably 0.1 to 30% by weight and more preferably 0.1 to 20% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of the polymeric material.
[74]
Mode for the Invention
[75] The production of an acoustic diaphragm using carbon nanotubes is generally achieved by dispersing carbon nanotubes as reinforcing agents to a polymeric material, thus avoiding the need for special processing or treatment. The present invention will be better understood from the following examples. However, these examples are not to be construed as limiting the scope of the invention.
[76] The physical properties of an acoustic diaphragm produced using a polymeric material and carbon nanotubes as reinforcing agents and those of an acoustic diaphragm produced using the polymeric material alone were measured and compared to evaluate changes in the physical properties of the polymeric material due to the use of the carbon nanotubes as reinforcing agents.
[77] In the following examples, carbon nanotubes were dispersed in a polymeric material for an acoustic diaphragm by the following procedure. First, carbon nanotubes were dispersed in a solvent. Then, a polymeric material was dissolved in the carbon nanotube solution. Thereafter, the solvent was evaporated or removed to obtain a state in which the carbon nanotubes as reinforcing agents were dispersed in the polymeric material.
[78]
[79] EXAMPLES
[80] Example 1
[81] An acoustic diaphragm was produced using polypropylene and carbon nanotubes as reinforcing agents dispersed in the polypropylene. The carbon nanotubes were used in an amount of 1% by weight, based on the weight of the polypropylene. The carbon nanotubes were single-walled carbon nanotubes (SWNTs) having an average diameter of 1 nm and a length of 1 μm.
[82] First, 10 ml of acetone as a solvent was put in an Erlenmeyer flask and 50 mg of the carbon nanotubes was added thereto. After the mixture was homogeneously mixed using an ultrasonicator, 5g of polypropylene was slowly added dropwise thereto with violent stirring. For homogeneous mixing, the resulting mixture was stirred for about 30 minutes. After the stirring, the homogeneous mixture was poured into a mold having a diameter of 20 mm and a thickness of 1 mm. The mold was placed in an oven at the temperature of 80°C and allowed to stand for about one day to evaporate the solvent and stabilize the carbon nanotubes within the polymeric material. The
polymeric material was detached from the mold to produce a polypropylene acoustic diaphragm using the carbon nanotubes as reinforcing agents.
[83]
[84] Example 2
[85] The procedure of Example 1 was repeated, except that a surfactant was further used to enhance the degree of dispersion of the carbon nanotubes without changing the conditions employed and the contents of the materials used in Example 1.
[86] As the surfactant, polyoxyethylene-8-lauryl ether, CH -(CH ) (OCH CH ) OCH
CH (hereinafter, referred to simply as "C12EO8") was used.
[87] First, 10 D of acetone as a solvent was put in an Erlenmeyer flask and 35 D of
C12EO8 was homogeneously dissolved in the solvent. 50 D of the carbon nanotubes was added to the C12EO8 solution. After the mixture was homogeneously mixed using an ultrasonicator, 5g of polypropylene was slowly added dropwise thereto with violent stirring. For homogeneous mixing, the resulting mixture was stirred for about 30 minutes. After the stirring, the homogeneous mixture was poured into a mold having a diameter of 20 mm and a thickness of 1 mm. The mold was placed in an oven at the temperature of 80°C and allowed to stand for about one day to evaporate the solvent and stabilize the carbon nanotubes within the polymeric material. The polymeric material was detached from the mold to produce a polypropylene acoustic diaphragm using the carbon nanotubes as reinforcing agents.
[88] The carbon nanotubes were homogeneously distributed in the acoustic diaphragm
(Example 2) produced using the surfactant, when compared to in the acoustic diaphragm (Example 1) produced without using any surfactant, as observed by an electronic microscope.
[89] Hereinafter, samples were produced using the surfactant in the same manner as in
Example 2, except that the kind and the amount of carbon nanotubes or graphite nanofibers were varied as indicated in Table 1. The changes in the elasticity of the samples were measured according to the kind of the polymeric materials used. The results are shown in Table 1. The increases in elasticity of the samples were evaluated on the basis of increases in the elasticity of the same polymer samples without using any carbon nanotubes or graphite nanofibers.
[90] The SWNTs (single wall nanotubes) used herein had an average diameter of 1 nm and a length of 1 μm. The graphite nanofibers (GNFs) used herein were herringbone type graphite nanofibers having an average diameter of 10 nm and a length of 1 D.
[91] Table 1
[92] * Note: PE - polyethylene, PP - polypropylene, PEI - polyetherimide, PET - polyethylene terephthalate
[93] [94] As can be seen from the results of Table 1, the samples produced using GNFs as reinforcing agents showed higher increases in elasticity than the samples produced using SWNTs as reinforcing agents. These results are believed to be due to strong bonding between the polymeric materials and GNFs arising from a high affinity of the polymeric materials for GNFs. The use of carbon nanotubes as reinforcing agents led to a considerable increase in the elasticity of the acoustic diaphragms.
[95] Carbon nanotubes or graphite nanofibers have a high mechanical strength due to the strong covalent bonding between carbon atoms and a high Young's modulus. In addition, carbon nanotubes or graphite nanofibers have a lower specific weight than the polymeric materials. Therefore, the use of carbon nanotubes or graphite nanofibers in acoustic diaphragms leads to considerable improvements in physical properties, such as strength, and a reduction in weight, thus making it possible to achieve superior sound quality. Carbon nanotubes dispersed in a material, particularly a polymeric material, for an acoustic diaphragm can serve to greatly improve the physical properties, such as elastic modulus, internal loss and density, required for the acoustic diaphragm.
[96] By appropriately controlling the kind and amount of the carbon nanotubes as reinforcing agents, methods for dispersing the carbon nanotubes and the kind of the dispersant (e.g., the surfactant), optimum acoustic diaphragm can be produced using the carbon nanotubes.
[97] Speakers to which the acoustic diaphragm of the present invention can be applied will be explained in more detail with reference to the accompanying drawings.
[98] In general, acoustic reproducers (e.g., speakers) are largely divided into horn speakers, system speakers for use in high-fidelity (Hi-Fi) audio systems (e.g., component systems) including a woofer, a midrange and a tweeter for covering a predetermined frequency band, general speakers for covering the entire frequency band by a single unit, micro speakers that are ultra-light in weight and ultra-slim in thickness designed to be used micro-camcorders, portable audio recorders (walkmans), personal digital assistants (PDAs), notebook computers, mobile communication terminals, headphones, cellular phones, telephones, radiotelegraphs, etc., receivers for use in mobile communication terminals, earphones whose part is inserted into the user's ear, and buzzers for receiving only a specific frequency band.
[99] The acoustic diaphragm of the present invention can be used in the above- mentioned speakers and is produced so as to have optimum physical properties according to the performance required for the speakers.
[100] An explanation of a micro speaker and a piezoelectric speaker comprising the acoustic diaphragm of the present invention will be provided below with reference to FIGs. 1 and 2, respectively.
[101] According to the structure of a micro speaker 10 shown in FIG. 1, a magnet 14 and a magnet plate 15 are disposed within a yoke 12, and a voice coil 13 surrounds the periphery of the magnet 14 and magnet plate 15. When a driving signal is generated in a state in which a diaphragm 16 is connected to both ends (i.e. a cathode and an anode) of the voice coil 13, the diaphragm is vibrated to produce a sound.
[102] When a driving signal is applied to the voice coil 13 of the micro speaker 10, a non- alternating (direct current (DC)) magnetic flux is generated in a magnetic circuit passing through the magnet plate 15 via the magnet 14, and an alternating (alternating current (AC)) rotating magnetic flux is generated in the voice coil 13 capable of moving upward and downward. The non-alternating magnetic flux responds to the alternating rotating magnetic flux according to Fleming's left-hand rule to cause attractive and repulsive forces. By the action of the attractive and repulsive forces, the diaphragm 16 and the voice coil 13 are vibrated upward and downward to produce a sound corresponding to the driving signal.
[103] To prevent occurrence of distortion of the diaphragm 16 arising from a high output of the micro speaker 10, many methods have been employed, for example, a method for reinforcing a diaphragm by introducing a corrugated shape to the diaphragm to prevent the diaphragm from being broken and a method for increasing the thickness of a diaphragm. Although these methods ensure prevention of distortion and breaking of diaphragms, they cause an increase in the amplitude of low-frequency sounds at a high output of 0.5 watts or higher and as a result, poor touch and unsatisfactory vibration (movement) of the diaphragms are caused, leading to the raise in the lowest resonant
frequency of the diaphragms. This raised lowest resonant frequency makes it difficult to reproduce low-frequency sounds.
[104] On the other hand, a reduction in the thickness of diaphragms leads to enhanced elasticity of the diaphragms but causes the problem of low strength of the diaphragms. The problem is solved by coating diaphragms with sapphire or diamond. However, coating of diaphragms having a small thickness (e.g., 10 μm or less) with sapphire or diamond causes hardening of the diaphragms.
[105] Although the thickness of the diaphragm according the present invention, which comprises carbon nanotubes or graphite nanofibers as reinforcing agents, is reduced, the elasticity of the diaphragm is improved without any deterioration in strength.
[106] FlG. 2 shows the structure of a piezoelectric speaker (a flat panel speaker).
[107] Referring to FlG. 2, a diaphragm 21 used in the piezoelectric speaker 20 is in the form of a thin plate and is required to be highly durable and lightweight.
[108] Due to the physical properties of carbon nanotubes or graphite nanofibers, the diaphragm 21 of the present invention is lightweight, is highly elastic and has a high mechanical strength as compared to conventional diaphragms. Therefore, the piezoelectric speaker 20 having the diaphragm 21 of the present invention can advantageously achieve superior sound quality.
[109] Further, the acoustic diaphragm of the present invention can be widely used in micro speakers, piezoelectric speakers, and small, medium and large speakers, regardless of the shape and structure of the speakers.
[HO]
Industrial Applicability
[111] As apparent from the above description, since the acoustic diaphragm of the present invention has excellent physical properties in terms of elastic modulus, internal loss, strength and weight, it can effectively achieve superior sound quality and a high output in a particular frequency band as well as in a broad frequency band.
[112] In addition, since the degree of dispersion of carbon nanotubes in the acoustic diaphragm of the present invention is improved, superior sound quality of speakers can be realized.
[113] Furthermore, the acoustic diaphragm of the present invention can be widely used in not only general speakers, including micro, small, medium and large speakers, but also in piezoelectric speakers (flat panel speakers).
[114] Although the present invention has been described herein with reference to the foregoing specific embodiments, those skilled in the art will appreciate that various modifications and changes are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims
Claims
[I] An acoustic diaphragm for converting electrical signals into mechanical signals to produce sounds wherein the acoustic diaphragm comprises carbon nanotubes or graphite nanofibers as reinforcing agents.
[2] The acoustic diaphragm according to claim 1, wherein the carbon nanotubes or graphite nanofibers are included or dispersed in the acoustic diaphragm to function as reinforcing agents. [3] The acoustic diaphragm according to claim 1, wherein the carbon nanotubes or graphite nanofibers are coated on the surface of the acoustic diaphragm to function as reinforcing agents. [4] The acoustic diaphragm according to claim 3, wherein the carbon nanotubes or graphite nanofibers are coated on the central portion of the acoustic diaphragm to function as reinforcing agnets. [5] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises a polymeric material as a major material. [6] The acoustic diaphragm according to claim 5, wherein the polymeric material is polyethylene (PE), polypropylene (PP), polyetherimide (PEI), polyethylene terephthalate (PET), or a mixture thereof. [7] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises a pulp or a mixture thereof with a fiber as a major material. [8] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises a metal selected from aluminum, titanium and beryllium as a major material. [9] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises a ceramic as a major material. [10] The acoustic diaphragm according to claim 1, wherein the carbon nanotubes or graphite nanofibers are single-walled carbon nanotubes, multi-walled carbon nanotubes, graphite nanofibers, or a mixture thereof.
[II] The acoustic diaphragm according to claim 10, wherein the carbon nanotubes or graphite nanofibers have a shape selected from straight, helical, branched shapes and mixed shapes thereof, or are a mixture of carbon nanotubes or graphite nanofibers having different shapes.
[12] The acoustic diaphragm according to claim 10 or 11, wherein the carbon nanotubes or graphite nanofibers includes at least one material selected from the group consisting of H, B, N, O, F, Si, P, S, Cl, transition metals, transition metal compounds, and alkali metals.
[13] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm
comprises a surfactant, stearic acid or a fatty acid to disperse the carbon nanotubes or graphite nanofibers. [14] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises 0.1 to 50% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of a major material for the acoustic diaphragm. [15] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises 0.1 to 30% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of a major material for the acoustic diaphragm. [16] The acoustic diaphragm according to claim 1, wherein the acoustic diaphragm comprises 0.1 to 20% by weight of the carbon nanotubes or graphite nanofibers, based on the weight of a major material for the acoustic diaphragm. [17] A speaker comprising the acoustic diaphragm according to any one of claims 1 to
16. [18] A micro speaker comprising the acoustic diaphragm according to any one of claims 1 to 16. [19] A piezoelectric speaker comprising the acoustic diaphragm according to any one of claims 1 to 16.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008535463A JP2009512327A (en) | 2005-10-14 | 2006-10-13 | Acoustic diaphragm and speaker including the same |
US12/089,900 US20090045005A1 (en) | 2005-10-14 | 2006-10-13 | Acoustic Diaphragm and Speakers Having the Same |
EP06799217A EP1949752A4 (en) | 2005-10-14 | 2006-10-13 | Acoustic diaphragm and speakers having the same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020050097140A KR100744843B1 (en) | 2005-10-14 | 2005-10-14 | Acoustic Diaphragm And Speaker Having The Same |
KR10-2005-0097140 | 2005-10-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2007043837A1 true WO2007043837A1 (en) | 2007-04-19 |
Family
ID=37943023
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/KR2006/004139 WO2007043837A1 (en) | 2005-10-14 | 2006-10-13 | Acoustic diaphragm and speakers having the same |
Country Status (6)
Country | Link |
---|---|
US (1) | US20090045005A1 (en) |
EP (1) | EP1949752A4 (en) |
JP (1) | JP2009512327A (en) |
KR (1) | KR100744843B1 (en) |
CN (1) | CN101288336A (en) |
WO (1) | WO2007043837A1 (en) |
Cited By (31)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090074228A1 (en) * | 2007-09-13 | 2009-03-19 | Harman International Industries, Incorporated | Loudspeaker cone body |
CN101600141A (en) * | 2008-06-04 | 2009-12-09 | 清华大学 | sound-producing device |
CN101969593A (en) * | 2010-07-07 | 2011-02-09 | 瑞声声学科技(深圳)有限公司 | Diaphragm |
US20110284317A1 (en) * | 2009-02-23 | 2011-11-24 | Mitsubishi Electric Corporation | Speaker diaphragm, speaker, and production method of speaker diaphragm |
CN102295806A (en) * | 2011-07-07 | 2011-12-28 | 吉林省神韵电子科技开发股份有限公司 | Speaker flat plate diaphragm made of vegetable fiber reinforced polypropylene composite material |
US8249280B2 (en) | 2009-09-25 | 2012-08-21 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8259968B2 (en) | 2008-04-28 | 2012-09-04 | Tsinghua University | Thermoacoustic device |
US8259967B2 (en) | 2008-04-28 | 2012-09-04 | Tsinghua University | Thermoacoustic device |
US8270639B2 (en) | 2008-04-28 | 2012-09-18 | Tsinghua University | Thermoacoustic device |
US8292436B2 (en) | 2009-07-03 | 2012-10-23 | Tsinghua University | Projection screen and image projection system using the same |
US8300856B2 (en) | 2008-12-30 | 2012-10-30 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8300854B2 (en) | 2008-10-08 | 2012-10-30 | Tsinghua University | Flexible thermoacoustic device |
US8300855B2 (en) | 2008-12-30 | 2012-10-30 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8331606B2 (en) | 2009-07-31 | 2012-12-11 | Tsinghua University | Diaphragm and loudspeaker using the same |
US8331586B2 (en) | 2008-12-30 | 2012-12-11 | Tsinghua University | Thermoacoustic device |
CN101610444B (en) * | 2008-06-18 | 2013-01-09 | 清华大学 | Sounding device |
US8385582B2 (en) | 2009-10-23 | 2013-02-26 | Tsinghua University | Damper and loudspeaker using the same cross-reference to related applications |
US8406450B2 (en) | 2009-08-28 | 2013-03-26 | Tsinghua University | Thermoacoustic device with heat dissipating structure |
US8452031B2 (en) | 2008-04-28 | 2013-05-28 | Tsinghua University | Ultrasonic thermoacoustic device |
US8457331B2 (en) | 2009-11-10 | 2013-06-04 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8494187B2 (en) | 2009-11-06 | 2013-07-23 | Tsinghua University | Carbon nanotube speaker |
US8515117B2 (en) | 2009-09-30 | 2013-08-20 | Tsinghua University | Bobbin and loudspeaker using the same |
US8537640B2 (en) | 2009-09-11 | 2013-09-17 | Tsinghua University | Active sonar system |
US8548188B2 (en) | 2009-10-23 | 2013-10-01 | Tsinghua University | Diaphragm, method making the same and loudspeaker using the same |
CN101594563B (en) * | 2008-04-28 | 2013-10-09 | 北京富纳特创新科技有限公司 | Sound generating device |
US8615096B2 (en) | 2009-08-07 | 2013-12-24 | Tsinghua University | Thermoacoustic device |
US8811631B2 (en) | 2009-11-16 | 2014-08-19 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
CN104135708A (en) * | 2014-08-14 | 2014-11-05 | 陈宏乔 | Fabricating methods of jade tridacna nacreous nano powder and speaker diaphragm |
US8905320B2 (en) | 2009-06-09 | 2014-12-09 | Tsinghua University | Room heating device capable of simultaneously producing sound waves |
CN109691131A (en) * | 2016-09-13 | 2019-04-26 | 松下知识产权经营株式会社 | Diaphragm for speaker and its manufacturing method and the loudspeaker for having used the diaphragm for speaker |
CN111711891A (en) * | 2020-06-24 | 2020-09-25 | 歌尔股份有限公司 | Dome, loudspeaker monomer and sound generating mechanism |
Families Citing this family (55)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7885697B2 (en) * | 2004-07-13 | 2011-02-08 | Dexcom, Inc. | Transcutaneous analyte sensor |
GB0426143D0 (en) * | 2004-11-26 | 2004-12-29 | Element Six Ltd | Rigid three-dimensional components |
KR100767260B1 (en) * | 2005-10-31 | 2007-10-17 | (주)케이에이치 케미컬 | Acoustic Diaphragm And Speaker Having The Same |
US8172035B2 (en) * | 2008-03-27 | 2012-05-08 | Bose Corporation | Waterproofing loudspeaker cones |
US7913808B2 (en) * | 2008-03-27 | 2011-03-29 | Bose Corporation | Waterproofing loudspeaker cones |
CN103987008B (en) * | 2008-12-30 | 2017-09-12 | 北京富纳特创新科技有限公司 | sound-producing device |
CN101931841A (en) * | 2009-06-26 | 2010-12-29 | 清华大学 | Voice coil framework and loudspeaker |
CN101931842B (en) * | 2009-06-26 | 2013-07-03 | 清华大学 | Voice coil framework and loudspeaker |
CN101990147B (en) | 2009-07-31 | 2013-08-28 | 清华大学 | Vibrating diaphragm and loudspeaker adopting same |
CN101990150A (en) | 2009-08-05 | 2011-03-23 | 鸿富锦精密工业(深圳)有限公司 | Loudspeaker |
CN101990142B (en) | 2009-08-05 | 2013-12-11 | 清华大学 | Voice coil lead wire and loudspeaker using same |
CN101998209A (en) | 2009-08-11 | 2011-03-30 | 清华大学 | Centering support chip and loudspeaker using same |
CN101998210A (en) * | 2009-08-11 | 2011-03-30 | 鸿富锦精密工业(深圳)有限公司 | Voice coil framework and loudspeaker using same |
TWI455610B (en) * | 2009-08-17 | 2014-10-01 | Hon Hai Prec Ind Co Ltd | Damper and speaker using the same |
CN102006539B (en) | 2009-08-28 | 2013-06-05 | 清华大学 | Speaker |
CN102026065A (en) * | 2009-09-15 | 2011-04-20 | 清华大学 | Centering disk and loudspeaker using centering disk |
CN102026069A (en) | 2009-09-17 | 2011-04-20 | 清华大学 | Voice coil and speaker using same |
CN102026068B (en) * | 2009-09-17 | 2016-06-08 | 清华大学 | Voice coil loudspeaker voice coil and use the speaker of this voice coil loudspeaker voice coil |
CN102026066B (en) | 2009-09-18 | 2013-10-09 | 清华大学 | Centering disk and loudspeaker using same |
TWI403184B (en) * | 2009-09-22 | 2013-07-21 | Hon Hai Prec Ind Co Ltd | Damper and speaker using the damper |
CN102036146A (en) * | 2009-09-30 | 2011-04-27 | 清华大学 | Vibrating diaphragm and speaker using same |
TWI448168B (en) * | 2009-09-30 | 2014-08-01 | Hon Hai Prec Ind Co Ltd | Damper and speaker using the same |
CN102065353B (en) * | 2009-11-17 | 2014-01-22 | 清华大学 | Vibrating membrane and speaker using same |
TWI501660B (en) * | 2010-01-15 | 2015-09-21 | Hon Hai Prec Ind Co Ltd | Diaphragm and louder speaker using the same |
US8452037B2 (en) | 2010-05-05 | 2013-05-28 | Apple Inc. | Speaker clip |
US8824722B2 (en) | 2010-06-28 | 2014-09-02 | Tsinghua University | Loudspeaker incorporating carbon nanotubes |
CN102295805B (en) * | 2011-07-07 | 2012-10-10 | 马春彪 | Loudspeaker diaphragm made from polypropylene blend |
KR101511282B1 (en) * | 2012-08-06 | 2015-04-10 | 주식회사 아모그린텍 | Diaphragm for speaker, manufacturing method thereof and speaker |
TWI539836B (en) | 2012-08-23 | 2016-06-21 | 逢甲大學 | Diaphragm structure for speaker and method of manufacturing method of the diaphragm structure |
US9820033B2 (en) | 2012-09-28 | 2017-11-14 | Apple Inc. | Speaker assembly |
KR101461410B1 (en) * | 2013-04-25 | 2014-11-13 | (주)아이노스 | Acoustic diaphragm |
CN103796139A (en) * | 2013-12-18 | 2014-05-14 | 东莞泉声电子有限公司 | Acoustic metal diaphragm |
CN105025428A (en) * | 2014-04-30 | 2015-11-04 | 福建省辉锐材料科技有限公司 | Loudspeaker diaphragm preparation method |
US9451354B2 (en) | 2014-05-12 | 2016-09-20 | Apple Inc. | Liquid expulsion from an orifice |
CN103957494B (en) * | 2014-05-20 | 2017-12-08 | 中国科学院宁波材料技术与工程研究所 | Vibrating membrane and its preparation method and application |
EP2958340A1 (en) * | 2014-06-17 | 2015-12-23 | Thomson Licensing | Optical microphone and method using the same |
KR101620321B1 (en) * | 2015-02-03 | 2016-05-12 | 한양대학교 에리카산학협력단 | Electrode integrated diaphragm, manufacturing method of the diaphragm and micro speaker using the diaphragm |
CN105113038B (en) * | 2015-06-24 | 2017-05-31 | 南通纺织丝绸产业技术研究院 | A kind of loudspeaker diaphragm materials and preparation method thereof |
US9900698B2 (en) | 2015-06-30 | 2018-02-20 | Apple Inc. | Graphene composite acoustic diaphragm |
CN106231507A (en) * | 2016-08-26 | 2016-12-14 | 广东欧珀移动通信有限公司 | A kind of vibrating diaphragm, speaker, sound chamber assembly and terminal |
CN106101966A (en) * | 2016-08-26 | 2016-11-09 | 广东欧珀移动通信有限公司 | Speaker and electronic equipment |
CN108513244B (en) * | 2017-02-27 | 2021-06-11 | 识骅科技股份有限公司 | Nano carbon tube composite vibration membrane for loudspeaker and its manufacturing method |
US11307661B2 (en) | 2017-09-25 | 2022-04-19 | Apple Inc. | Electronic device with actuators for producing haptic and audio output along a device housing |
US10873798B1 (en) | 2018-06-11 | 2020-12-22 | Apple Inc. | Detecting through-body inputs at a wearable audio device |
US10757491B1 (en) | 2018-06-11 | 2020-08-25 | Apple Inc. | Wearable interactive audio device |
US11334032B2 (en) | 2018-08-30 | 2022-05-17 | Apple Inc. | Electronic watch with barometric vent |
US11561144B1 (en) | 2018-09-27 | 2023-01-24 | Apple Inc. | Wearable electronic device with fluid-based pressure sensing |
CN109467930A (en) * | 2018-11-28 | 2019-03-15 | 惠州市威隆展业实业有限公司 | A kind of earphone diaphragm material and preparation method thereof |
CN114399012B (en) | 2019-04-17 | 2024-08-06 | 苹果公司 | Wireless locatable tag |
CN110677785B (en) * | 2019-09-20 | 2021-06-15 | 深圳海翼智新科技有限公司 | Loudspeaker cone, manufacturing method thereof and loudspeaker |
CN113542986B (en) * | 2020-04-17 | 2023-11-10 | 歌尔股份有限公司 | Loudspeaker diaphragm and sound generating device |
CN111818425A (en) * | 2020-06-08 | 2020-10-23 | 深圳市汉嵙新材料技术有限公司 | Vibrating diaphragm, sound production device, microphone assembly and vibrating diaphragm manufacturing method |
CN111711890A (en) * | 2020-06-24 | 2020-09-25 | 歌尔股份有限公司 | Dome, loudspeaker monomer and sound generating mechanism |
CN112511956B (en) * | 2020-11-02 | 2023-04-28 | 歌尔股份有限公司 | Vibrating plate for sound generating device and sound generating device |
CN114554365B (en) * | 2022-02-22 | 2024-10-01 | 深圳羽声电子有限公司 | Elastic wave vibrating diaphragm |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004015261A (en) * | 2002-06-05 | 2004-01-15 | Foster Electric Co Ltd | Diaphragm for electro-acoustic converter |
JP2004032425A (en) * | 2002-06-26 | 2004-01-29 | Mitsubishi Pencil Co Ltd | Composite carbon diaphragm and its manufacturing method |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5730496A (en) * | 1980-07-30 | 1982-02-18 | Nippon Gakki Seizo Kk | Diaphragm for electroacoustic transducer |
JPS58153491A (en) * | 1982-03-08 | 1983-09-12 | Matsushita Electric Ind Co Ltd | Speaker diaphragm |
JPS6264199A (en) * | 1985-09-13 | 1987-03-23 | Nippon Columbia Co Ltd | Manufacture of speaker diapharagm |
US6097829A (en) * | 1995-04-06 | 2000-08-01 | Precision Power, Inc. | Fiber-honeycomb-fiber sandwich speaker diaphragm and method |
WO2003013199A2 (en) * | 2001-07-27 | 2003-02-13 | Eikos, Inc. | Conformal coatings comprising carbon nanotubes |
JP3919173B2 (en) | 2002-04-19 | 2007-05-23 | フォスター電機株式会社 | Diaphragm for electroacoustic transducer |
JP2003319490A (en) * | 2002-04-19 | 2003-11-07 | Sony Corp | Diaphragm and manufacturing method thereof, and speaker |
JP3827153B2 (en) | 2002-06-18 | 2006-09-27 | フォスター電機株式会社 | Diaphragm for electroacoustic transducer |
ATE380384T1 (en) * | 2003-04-24 | 2007-12-15 | Carbon Nanotechnologies Inc | CONDUCTIVE CARBON NANOTUBE POLYMER COMPOSITE |
US7531267B2 (en) * | 2003-06-02 | 2009-05-12 | Kh Chemicals Co., Ltd. | Process for preparing carbon nanotube electrode comprising sulfur or metal nanoparticles as a binder |
US8455583B2 (en) * | 2004-08-02 | 2013-06-04 | University Of Houston | Carbon nanotube reinforced polymer nanocomposites |
KR100767260B1 (en) * | 2005-10-31 | 2007-10-17 | (주)케이에이치 케미컬 | Acoustic Diaphragm And Speaker Having The Same |
WO2009036282A1 (en) * | 2007-09-13 | 2009-03-19 | Harman International Industries, Inc. | Loudspeaker cone body |
-
2005
- 2005-10-14 KR KR1020050097140A patent/KR100744843B1/en not_active IP Right Cessation
-
2006
- 2006-10-13 EP EP06799217A patent/EP1949752A4/en not_active Withdrawn
- 2006-10-13 CN CNA2006800383017A patent/CN101288336A/en active Pending
- 2006-10-13 JP JP2008535463A patent/JP2009512327A/en not_active Withdrawn
- 2006-10-13 WO PCT/KR2006/004139 patent/WO2007043837A1/en active Application Filing
- 2006-10-13 US US12/089,900 patent/US20090045005A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2004015261A (en) * | 2002-06-05 | 2004-01-15 | Foster Electric Co Ltd | Diaphragm for electro-acoustic converter |
JP2004032425A (en) * | 2002-06-26 | 2004-01-29 | Mitsubishi Pencil Co Ltd | Composite carbon diaphragm and its manufacturing method |
Non-Patent Citations (1)
Title |
---|
See also references of EP1949752A4 * |
Cited By (50)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9247368B2 (en) * | 2007-09-13 | 2016-01-26 | Harman International Industries, Incorporated | Loudspeaker cone body |
US20090074228A1 (en) * | 2007-09-13 | 2009-03-19 | Harman International Industries, Incorporated | Loudspeaker cone body |
CN101594563B (en) * | 2008-04-28 | 2013-10-09 | 北京富纳特创新科技有限公司 | Sound generating device |
US8452031B2 (en) | 2008-04-28 | 2013-05-28 | Tsinghua University | Ultrasonic thermoacoustic device |
US8259968B2 (en) | 2008-04-28 | 2012-09-04 | Tsinghua University | Thermoacoustic device |
US8259967B2 (en) | 2008-04-28 | 2012-09-04 | Tsinghua University | Thermoacoustic device |
US8270639B2 (en) | 2008-04-28 | 2012-09-18 | Tsinghua University | Thermoacoustic device |
CN101600141A (en) * | 2008-06-04 | 2009-12-09 | 清华大学 | sound-producing device |
CN101610444B (en) * | 2008-06-18 | 2013-01-09 | 清华大学 | Sounding device |
US8300854B2 (en) | 2008-10-08 | 2012-10-30 | Tsinghua University | Flexible thermoacoustic device |
CN101715160B (en) * | 2008-10-08 | 2013-02-13 | 清华大学 | Flexible sound producing device and sound producing flag |
US8331586B2 (en) | 2008-12-30 | 2012-12-11 | Tsinghua University | Thermoacoustic device |
US8763234B2 (en) | 2008-12-30 | 2014-07-01 | Beijing Funate Innovation Technology Co., Ltd. | Method for making thermoacoustic module |
US8306246B2 (en) | 2008-12-30 | 2012-11-06 | Beijing FUNATE Innovation Technology Co., Ld. | Thermoacoustic device |
US8311245B2 (en) | 2008-12-30 | 2012-11-13 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8311244B2 (en) | 2008-12-30 | 2012-11-13 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8315414B2 (en) | 2008-12-30 | 2012-11-20 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8315415B2 (en) | 2008-12-30 | 2012-11-20 | Beijing Funate Innovation Technology Co., Ltd. | Speaker |
US8325948B2 (en) | 2008-12-30 | 2012-12-04 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8325949B2 (en) | 2008-12-30 | 2012-12-04 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8325947B2 (en) | 2008-12-30 | 2012-12-04 | Bejing FUNATE Innovation Technology Co., Ltd. | Thermoacoustic device |
US8331587B2 (en) | 2008-12-30 | 2012-12-11 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8300855B2 (en) | 2008-12-30 | 2012-10-30 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8300856B2 (en) | 2008-12-30 | 2012-10-30 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8345896B2 (en) | 2008-12-30 | 2013-01-01 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8462965B2 (en) | 2008-12-30 | 2013-06-11 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US8379885B2 (en) | 2008-12-30 | 2013-02-19 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic module, thermoacoustic device, and method for making the same |
US20110284317A1 (en) * | 2009-02-23 | 2011-11-24 | Mitsubishi Electric Corporation | Speaker diaphragm, speaker, and production method of speaker diaphragm |
DE112010000679B4 (en) * | 2009-02-23 | 2021-04-01 | Mitsubishi Electric Corp. | SPEAKER MEMBRANE AND SPEAKER |
US9027699B2 (en) * | 2009-02-23 | 2015-05-12 | Mitsubishi Electric Corporation | Speaker diaphragm, speaker, and production method of speaker diaphragm |
US8905320B2 (en) | 2009-06-09 | 2014-12-09 | Tsinghua University | Room heating device capable of simultaneously producing sound waves |
US8292436B2 (en) | 2009-07-03 | 2012-10-23 | Tsinghua University | Projection screen and image projection system using the same |
US8331606B2 (en) | 2009-07-31 | 2012-12-11 | Tsinghua University | Diaphragm and loudspeaker using the same |
US8615096B2 (en) | 2009-08-07 | 2013-12-24 | Tsinghua University | Thermoacoustic device |
US8406450B2 (en) | 2009-08-28 | 2013-03-26 | Tsinghua University | Thermoacoustic device with heat dissipating structure |
US8537640B2 (en) | 2009-09-11 | 2013-09-17 | Tsinghua University | Active sonar system |
US8249280B2 (en) | 2009-09-25 | 2012-08-21 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8515117B2 (en) | 2009-09-30 | 2013-08-20 | Tsinghua University | Bobbin and loudspeaker using the same |
US8548188B2 (en) | 2009-10-23 | 2013-10-01 | Tsinghua University | Diaphragm, method making the same and loudspeaker using the same |
US8385582B2 (en) | 2009-10-23 | 2013-02-26 | Tsinghua University | Damper and loudspeaker using the same cross-reference to related applications |
US8494187B2 (en) | 2009-11-06 | 2013-07-23 | Tsinghua University | Carbon nanotube speaker |
US8457331B2 (en) | 2009-11-10 | 2013-06-04 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
US8811631B2 (en) | 2009-11-16 | 2014-08-19 | Beijing Funate Innovation Technology Co., Ltd. | Thermoacoustic device |
CN101969593A (en) * | 2010-07-07 | 2011-02-09 | 瑞声声学科技(深圳)有限公司 | Diaphragm |
CN102295806A (en) * | 2011-07-07 | 2011-12-28 | 吉林省神韵电子科技开发股份有限公司 | Speaker flat plate diaphragm made of vegetable fiber reinforced polypropylene composite material |
CN104135708A (en) * | 2014-08-14 | 2014-11-05 | 陈宏乔 | Fabricating methods of jade tridacna nacreous nano powder and speaker diaphragm |
CN104135708B (en) * | 2014-08-14 | 2017-08-25 | 陈宏乔 | The preparation method of jadeization giant clam nacre nano powder and the diaphragm of loudspeaker |
CN109691131A (en) * | 2016-09-13 | 2019-04-26 | 松下知识产权经营株式会社 | Diaphragm for speaker and its manufacturing method and the loudspeaker for having used the diaphragm for speaker |
CN111711891A (en) * | 2020-06-24 | 2020-09-25 | 歌尔股份有限公司 | Dome, loudspeaker monomer and sound generating mechanism |
CN111711891B (en) * | 2020-06-24 | 2022-06-07 | 歌尔股份有限公司 | Dome, loudspeaker monomer and sound generating mechanism |
Also Published As
Publication number | Publication date |
---|---|
JP2009512327A (en) | 2009-03-19 |
KR100744843B1 (en) | 2007-08-06 |
CN101288336A (en) | 2008-10-15 |
US20090045005A1 (en) | 2009-02-19 |
EP1949752A1 (en) | 2008-07-30 |
KR20070041226A (en) | 2007-04-18 |
EP1949752A4 (en) | 2009-12-30 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20090045005A1 (en) | Acoustic Diaphragm and Speakers Having the Same | |
US20080260188A1 (en) | Acoustic Diaphragm and Speaker Having the Same | |
JP3630669B2 (en) | Composite carbon diaphragm and manufacturing method thereof | |
JP2003319491A (en) | Diaphragm and manufacturing method thereof, and speaker | |
US8331606B2 (en) | Diaphragm and loudspeaker using the same | |
JP2003319490A (en) | Diaphragm and manufacturing method thereof, and speaker | |
TWI539836B (en) | Diaphragm structure for speaker and method of manufacturing method of the diaphragm structure | |
US20130309400A1 (en) | Method for making diaphragm | |
CN101715155A (en) | Earphone | |
JP2012001804A (en) | Magnesium-based composite material and preparation method thereof, and application thereof in sounding device | |
CN101656907A (en) | Sound box | |
JP2008160360A (en) | Frame for speaker and speaker using same | |
US20130301868A1 (en) | Bobbin and loudspeaker using the same | |
KR20060008898A (en) | Beryllium acoustic transducer | |
JP6495866B2 (en) | Speaker unit | |
KR101461410B1 (en) | Acoustic diaphragm | |
KR102587063B1 (en) | Acoustic diaphragm including graphene and acoustic device adopting the same | |
CN108513244B (en) | Nano carbon tube composite vibration membrane for loudspeaker and its manufacturing method | |
KR102344408B1 (en) | Magnetic vibration panel manufacturing method and magnetic vibration panel manufactured using it, speaker unit using it | |
KR101708863B1 (en) | A metal thin-film magnet and speaker having the same and method for forming the metal thin-film magnet | |
JPH1051892A (en) | Driver for headphone | |
CN208353569U (en) | Graphene sound diaphragm | |
JP5407425B2 (en) | Speaker diaphragm, speaker using the same, and electronic device and apparatus using the speaker | |
TWI420916B (en) | Diaphragm and loudspeaker using the same | |
Sakamoto et al. | Titanium and Hardened Carbon Film Composite Speaker Diaphragm |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200680038301.7 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 12089900 Country of ref document: US |
|
ENP | Entry into the national phase |
Ref document number: 2008535463 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2006799217 Country of ref document: EP |