Patent Grant
7986805
1. Field of the Invention
This invention relates to the field of electric to acoustic transducer systems and acoustic to electric transducer systems, and more specifically, to a system for an improved unique diaphragm having a plurality of acoustic elements supported by the diaphragm.
2. Description of the Related Art
Common electric to acoustic transducer devices, and acoustic to electric transducer devices, are well documented in the following text and anthologies: Acoustic Engineering, Harry F. Olson, Ph.D., Van Norstrand Company, Inc., New Jersey, 1957 (Library of Congress catalogue card No. 57-8143) (hereinafter referred to as “Olson”); Loudspeakers, An anthology of articles on loudspeakers from the pages of the Journal of the Audio Engineering Society Vol. 1-Vol. 25 (1953-1977), 2nd Edition, Audio Engineering Society, Inc., New York, N.Y.; and Loudspeakers, An anthology of articles on loudspeakers from the pages of the Journal of the Audio Engineering Society Vol. 26-Vol. 31 (1978-1983), Audio Engineering Society, Inc., New York, N.Y., each of which are hereby incorporated by reference. Many design efforts have focused not only on the physical characteristics of the materials, such as high modulus E, low-density ρ, high E/ρ and low over all weight, but also on configuration of an acoustic diaphragm. In one approach, U.S. Pat. No. 1,757,451 (1930, Crane) consists of the impressed holes, ribs, or humps in the diaphragm, which may be filled with a damping material and preferably arranged in a logarithmic curve. This attempt related to a method of limiting or attenuating standing wave or divisional vibration by modification of the propagation characteristics of the diaphragm.
There have been some prior attempts at solve the problem of undesirable vibrations by incorporating layered fibers into an acoustic diaphragm. For example, Japanese Patent Application S58-108896 (1983, Guyot) disclosed a loudspeaker cone formed by a laminated high elasticity fiber sheet with polymer. Accordingly, Japanese Issued U.S. Pat. No. 2,693,447 (1997, Tomiyake, et al.) disclosed a loudspeaker cone consisting of a high elasticity fiber with polymer stripes where every stripe is directed to the radial direction from the cone neck. Further, Japanese Issued Patent No. 0946,038 (1979, Morita, et al.) describes a dome-shaped diaphragm consisting of a high elasticity fiber with polymer wherein all fibers are directed to longitude of the dome.
However, in each of the applications described above, the construction and techniques employed did not take advantage of nor incorporate the advantages of the natural characteristics of layering as seen in a human eardrum. Another example of an advantageous naturally occurring design to solve the problem of undesirable vibrations is one which reflects the advantages of the natural layered-fiber characteristics of a feather. Yet, in each of the applications described above, the construction and techniques employed did not take advantage of nor incorporate advantageous characteristics of a feather. Thus, an acoustic diaphragm having the advantageous characteristics of a human eardrum and of a feather has not been achieved.
Various aspects of the present invention may be illustrated by an understanding of the layering of elements of the human eardrum, as well as the layering of a feather, to produce an improved acoustic diaphragm based on such an understanding natural principles.
It is an object of this invention to provide a naturally oriented acoustic diaphragm for use not only an electric to acoustic transducer systems including speaker, headphone, earphone, telephone and hearing aids, but also in acoustic to electric transducer systems such as a microphone.
It is another object of the invention to provide an improved naturally oriented acoustic diaphragm that is interchangeable with current electric to acoustic transducer and acoustic to electric transducer devices, apparatus and systems wherein significant improvements are obtained.
It is another object of the invention to provide an improved naturally oriented acoustic diaphragm having a simple construction and that is relatively inexpensive to manufacture.
It is another object of the invention to provide an improved naturally oriented acoustic diaphragm that is weatherproof and has persistency.
It is another object of the invention to provide a method of making a naturally oriented acoustic diaphragm.
It is another object of the invention to provide an electric to acoustic transducer and an acoustic to electric transducer using a naturally oriented acoustic diaphragm.
The above, and other objects of the invention, are achieved by an acoustic diaphragm with a driver connected to the acoustic diaphragm for communication of acoustic energy comprising:
Even further improvements in performance are achieved by dual-layer construction of the acoustic diaphragm so that:
A dual layer of the acoustic elements, in an acute angle to normal to the driver, is aligned out-of-phase against the other layer, providing significant improvements to the characteristics of the acoustic diaphragm.
However, the inventor emphasizes that noticeable improvements in an acoustic diaphragm are achieved even in a diaphragm having only a single layer of acoustic element when the matrix has a stiffness of a conventional acoustic diaphragm or less.
The above and other objects of the invention are achieved with a method of making a naturally oriented acoustic diaphragm with a driver connected to the diaphragm for communication of acoustic energy having a plurality of acoustic elements equally spaced and a matrix supported by the diaphragm, and extending radially at a uniform acute angle to normal at each connection to the driver, with the acoustic elements oriented in a selected stiffness pattern surrounding the driver.
A further method of making a naturally oriented acoustic diaphragm is achieved by using a fiber-reinforced-plastic, wherein fiber is the acoustic element and plastic is the matrix.
A further method of making the naturally oriented acoustic diaphragm is achieved by supplementing the conventional acoustic diaphragm with the acoustic elements described herein.
A further method of making a naturally oriented acoustic diaphragm is achieved by plastic-molding a diaphragm with the acoustic elements. The principle and methods of the invention are also applied to a plane drive acoustic diaphragm, wherein a vibratory member having a plurality of elements formed from an electrically excited plane drive system is adapted to said acoustic diaphragm to cause each element to vibrate when the exciter is electrically or electro-magnetically energized, each element having a proximate end coupled to a central portion of the acoustic diaphragm and extending radially at a uniform acute angle to normal of a central portion of the diaphragm.
The principles and methods of the present invention can be applied in every species of acoustic diaphragm, regardless of the frequency range, and substantial improvement can be obtained over the conventional acoustic diaphragm.
The above and other objects of the invention may also be achieved by an improved electric to acoustic and acoustic to electric transducer system using a naturally-oriented acoustic diaphragm with acoustic elements for producing sound and electric signals. Such a transducer may also include a voice coil assembly. A field structure, in its common form, includes a magnet and a pole piece that generates an intense, symmetrical, magnetic field in a gap proximate to the voice coil. A frame structure is coupled to and supports the acoustic diaphragm with a voice coil and a magnetic field structure.
FIG. 8A to 8AC show the circular sectional views of the arrangement of acoustic element at the periphery of acoustic diaphragm according to the invention.
An acoustic diaphragm is described herein. In the following description, numerous specific details are set forth by way of exemplary embodiments in order to provide a more thorough description of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention. The preferred embodiments of the inventions are described herein in the Figures and Detailed Description. Unless specifically noted, it is intended that the words and phrases in the specification and claims be given the ordinary and accustomed meaning as understood by those of ordinary skill in the applicable art or arts. If any other meaning is intended, the specification will specifically state that a special meaning is being applied to a word or phrase.
The present invention uses an alternative approach to those of the prior art, by taking “nature” into account to solve the problem of undesirable vibrations with efficient and uniform acoustic energy transmission, damping and reinforcement in acoustic diaphragms. As described in the Olson, (p. 558,) “[t]he ultimate significant destination of all reproduced sound is the human ear.” Human hearing is initiated by sound vibrating the eardrum.
In practice, original sound is transformed into an electric signal by the diaphragm of a microphone, transmitted electrically, and then regenerated as sound by a diaphragm in sound reproduction equipment in order to vibrate the above mentioned eardrum.
It is true that the human ear is still, ultimately, the best judge of sound quality, although more advanced measuring equipment and sophisticated measuring methods have been developed and introduced. Still, considerable discrepancy exists between data obtained by measuring equipment and actual sound as qualified by the human auditory sense.
According to Olson (pp. 558-9,) “[t]he physiological and psychological effects of the reproduced sound are the most important factors in any sound reproducing system . . . . An enormous amount of valuable data relating to speech and hearing have been collected. This information is extremely useful in the development and design of sound reproducing equipment . . . . When a sound wave impinges upon the ear, it enters the ear canal and causes the eardrum to vibrate.”
The inventor herein considers a human “eardrum” as of the ultimate acoustic diaphragm, as obtained through an evolutionary process.
The Human Eardrum as a Model for an Acoustic Diaphragm
Referring to the Speech and Hearing Science, (p. 550), Willard R. Zemlin, prof., 1981 by Prentice Hall, Inc., Englewood Ciffs, N.J. 07632, (referred to below as “Zemlin”) and ATLAS of OTOLOGY, (Jikagaku Atolasu), (p. 54), Yasuya Nomura, M.D., Fumihisa Hiraide, M.D., 1974 by CHUGAI-IGAKU Co., Tokyo, (referred to below as “Nomura), the contents of each of which are hereby incorporated by reference. Zemlin describes a human eardrum as follows: “[s]tructurally the eardrum consists of three layers of tissue: a thin outer cutaneous layer, which is continuous with the lining of the external auditory meatus; a fibrous middle layer, which is largely responsible for the resilience of the eardrum; and an internal layer of serous (mucous) membrane, which is continuous with the lining of the tympanic cavity. The fibrous layer actually contains two layers closely connected one with the other. The more superficial of the two consists of fibers that radiate from the center toward the periphery. These fibers are rather evenly distributed throughout most of the tympanic membrane, giving the fibrous layer a fancied resemblance to spokes in a wheel (referred to herein as “radial fibers.”) The deeper layer is composed of concentric rings of fibrous tissue which have an uneven distribution (referred to herein as “circular fibers.”) Their density is greatest toward the periphery, and in the center where the membrane attaches to the end of the manubrium of the malleus.”
As described above, the two fibrous layers are coupled to the malleus and closely connected, but neither weaved nor knitted tissue. It has been medically proven that these layers can be independently separated. See, Middle Ear, Inner Ear Scanning Microscope Atlas, (Chuuji, Naiji Sousadenken Atolasu), (pp. 4-5), Yasuo Harada, Prof., 1980 by Kanahara & Co., LTD. Tokyo, (hereinafter, “Harada”) the contents of which are hereby incorporated by reference.
An acoustic diaphragm design may be inspired by the human eardrum, which may be characterized by:
(1) both a radial fiber and circular fibers coupled to a driver;
(2) efficient and uniform transmission of acoustic energy achieved without the barrier of twist or twine due to weave or knit;
(3) adequate internal loss induced in the fiber material itself, where additional damping is given by the out-of-phase motion of each layer when vibrated, such that the radial fiber moves in a circular direction and the circular fiber moves in a radial direction;
(4) reduction of standing waves reflected from the periphery and manubrium of the malleus by circular fiber;
(5) reinforce the eardrum by the fiber stiffness within adequate weight. As explained above, a fiber of an eardrum is an example of a functionally active element which the inventor hereinafter calls an “acoustic element”; and
(6) an eardrum coupled to a hearing organ by a leverage type mechanical linkage. Consequently, the eardrum configuration is not directly applicable to the acoustic diaphragm that requires mechanically isolated reciprocal motion.
A Feather as a Model for an Acoustic Diaphragm
Another embodiment of the novelty of present invention is illustrated by another example of a natural damped membrane—a feather. A feather configuration is a superior model for an acoustic diaphragm since it has remained the same for over one hundred million years.
A close-up of a feather is shown in The Nihon Keizai Shinban (Daily News), Oct. 27, 2002, p. 26, “A Diffraction Grating in Nature” (hereinafter, “Nikkei”) hereby incorporated by reference. For discussion in the present description, a feather is comprised of a non-linear needle-leaf like “twig” (aerodynamic energy 20 transmitting element) coupled to a “bough” (a driver) at an acute angle and is aligned on a single layer. Another twig layer, which is coupled to an adjacent bough, is cross-plied to the first twig layer. A feather's twig is an aerodynamical functional element with air as the matrix.
Accordingly, a feather configuration is characterized by:
The acoustic element of the present invention is inspired by and has the novelty of an eardrum's fiber and a feather's twig, as described above. The physical configuration of one preferred embodiment of the present invention is shown in
In
Concurrently, reinforcement for a normal component vector and a tangential component vector are given by acoustic elements 1 and 10. Internal loss is thus induced between acoustic elements 1 and 10 and the matrix of the acoustic diaphragm.
A normal component and a tangential component are equalized when said acute angle 4 is a 45-degree angle, wherein the area comprised of 8, 9a, 8a, 9 becomes maximum. A 45-degree angle, plus or minus 10-degrees, is acceptable because of the reduction of the above mentioned vector is less than 30%. An acute angle is determined with respect to the tangential plane on the acoustic diaphragm.
Referring to
It is preferable to have a second layer of acoustic element 19 over laid on the first layer in an out-of-phase relationship to each other, likewise shown in
Referring to
It is preferable to have a second layer of acoustic element 23 over laid on the first layer, in an out-of-phase relationship to each other, likewise shown in
Uniform acoustic energy distribution and attenuation for reflected acoustic waves are obtained when the acute angles of the acoustic element to each normal at the radius, and more preferably every radius, are substantially equal. Accordingly, in one preferred embodiment, an acoustic element has a curved portion or a bent portion fashioned in a logarithmic spiral.
When each layer of the above mentioned acute angle 4 is at 45-degrees, the result is a cross-angle of two acoustic elements of dual layers at 90-degrees. Layering of more than two layers is possible.
This invention is comprised of five structures as listed in Table 1.
In one embodiment of the invention, greatly increased performance over the prior art was achieved employing a fiber-reinforced plastic, (see Table 2-1(a)), using the “off-the-shelf” fibers of Table 3 as the acoustic element.
A method for producing a cone-type acoustic diaphragm of the present invention may comprise the following stages:
The acoustic diaphragm of the present invention may be understood to incorporate the advantageous characteristics of a human eardrum and a feather (refer to “Zemlin”, “Nomura”, “Harada”, and “Nikkei” as seen in the following explanations.
For the cone-type acoustic diaphragm of
(a) Acoustic elements 31, 31a and 31b of the diaphragm may be associated to an eardrum's fibers and a feather's twigs.
(b) Each element has a proximate end which is coupled to driver 3, as are an eardrum's malleus and a feather's bough.
(c) Each element extends radially at a uniform acute angle to normal of driver 3, as is a feather's twig, which extends from the bough at a uniform acute angle.
(d) Adequate internal loss is induced between the fiber and the matrix, as with an eardrum's fiber composition and a feather's twigs, with air as a matrix.
(e) In a dual layer construction, the direction of fibers in the first layer is out-of-phase relative to the direction of fibers of the second layer, as is the case with an eardrum's fibers and a feather's twigs.
(f) The acoustic element reduces standing waves reflected from the periphery and driver as with an eardrum's fibers and a feather's twigs.
(g) Regarding the required amount of fiber within adequate weight, the inventor has discovered in practice that an acoustic diaphragm having a weight/area ratio of up to three times, preferably twice, that of the human eardrum presents sufficient characteristics. The human eardrum weight/area ratio is 0.25 mg/mm2 (14 mg/effective movable area (55 mm2)), (refer to “Zemlin” and “Nomura”), hereinafter referred to as a “G/S ratio.” Reduction of the G/S ratio increases an effective frequency bandwidth of an acoustic diaphragm.
A method for producing a dome-type acoustic diaphragm of the present invention may comprise the following stages:
The acoustic diaphragm of the present invention may be understood to incorporate the advantageous characteristics of a human eardrum and a feather (refer to “Zemlin”, “Nomura”, “Harada”, and “Nikkei” as seen in the following explanations.
For the dome-type acoustic diaphragm of
In the above described cone or dome type acoustic diaphragm, it is possible to use any kind of fiber listed in Table 3 in single or mixed mode. For example, an aromatic-polyaramid fiber is preferred when increase of internal loss and damping is required.
In another embodiment of the invention, a combination of
Thus, the acoustic diaphragm of the present invention utilizes an “off the shelf” fiber as an acoustic element. This represents a major advancement over any conventional acoustic diaphragm with the result of natural high-fidelity sound reproduction with wide frequency response, high efficiency and large dynamic range in real presence with high persistency and is weather proof.
Another embodiment of the invention greatly increases performance over the prior art using standard “off the shelf” unidirectional “carbon-fiber prepreg” (Table 2-1(b)) as an acoustic element. Cut out the carbon-fiber prepreg according to a specific size and shape of the required acoustic diaphragm is shown in
In order to make the cone-type acoustic diaphragm of the present invention, perform the following steps:
In order to make a dome-type acoustic diaphragm of the present invention, perform the following steps:
In the above mentioned cone or dome type acoustic diaphragms, it is possible to use any kind of prepreg utilizing the fibers listed in Table 3, or a mixture of them as in Table 2-1(c). An aromatic-polyaramid fiber is preferred when an increase internal loss and damping is required.
In the above description of fiber-oriented structures, it is possible to fix a fiber with a lateral adherable yarn, ribbon or tape, including heat-shrink type, without bending or weaving of the acoustic element for easy manufacturing.
As shown in
In another embodiment of the invention, Supplemental Structures Table 2-2 shows greatly increased performance over the prior art and a further simplified fabrication process with reduced cost can be achieved using standard “off the shelf” materials listed in Table 3, or any kind of fixable material supplemented to the conventional acoustic diaphragm as an acoustic element.
In order to make an acoustic diaphragm of the present invention using standard “off-the-shelf” materials, perform the following steps:
In a modified embodiment of the invention, Removal Structures Table 2-3, greatly increased performance over the prior art and further simplified fabrication and a reduced cost was achieved using standard “off the shelf” material, such as in Table 3, whereby removing unnecessary material from an acoustic diaphragm and remaining an acoustic element.
Detailed methods to achieve such improved performance are as follows:
All supplemental and removal processes can be applied before or after the cone or dome shape is formed.
The desired space between the acoustic element parts should be made to be shorter than the wave length of the respective carrying frequency of the acoustic diaphragm.
In a modified embodiment of the invention, Mold Structures Table 2-4, greatly increased performance over the prior art and further simplified fabrication and reduced cost was achieved using standard “off-the-shelf” monolithic plastic material.
In a modified embodiment of the invention, use of materials in Emboss Structures Table 2-5, greatly increased performance over the prior art and further simplified fabrication. Reduced cost was achieved using standard “off-the-shelf” materials listed in Table 3.
The acoustic element extends over the driver in a circular fashion, and it is preferably more than 20% of its width.
An acoustic element is also applicable to an acoustic diaphragm with concentric corrugation as well as a passive radiator and improves its characteristics.
In a preferred embodiment of the invention, in order to provide efficient transmission of acoustic energy, an acoustic element extends and couples with driver as in Table 4. Greatly increased performance over the prior art was achieved using the standard “off-the-shelf” materials of the Table 3 in this embodiment.
In a modified embodiment of the invention greatly increased performance over the prior art was achieved using standard ferromagnetic material as an acoustic diaphragm of plane drive electro-magnetic system, such as telephone, earphone and hearing-aid, is shown in
For a piezoelectric material, or electrostatic material,
In order to provide stable reciprocal motion of the driver, referring to the well-known “tripod” principle, three or more acoustic elements are necessary.
In typical operation, when a current is applied to voice coil 12, a corresponding electromagnetic field is produced at a right angle to the flow of current and to the permanent magnetic field in gap 92, causing a mechanical force that drives voice coil system 12, and correspondingly the conical diaphragm 94, in a reciprocating piston-like motion indicated by arrow 98. More specifically, the audio signal applied to voice coil 12 is typically an alternating current in the form of a sine wave of varying frequency. The flow in voice coil 12 of current in one direction on the positive half of the alternating cycle will cause a magnetic field of polarity and will result in motion of voice coil 12 and attached diaphragm 94 in a first (e.g., outward) direction. When the current through voice coil 12 reverses on the negative half the cycle, the polarity of the magnetic field generated by the voice coil 12 reverses, and the motion of voice coil 12 and diaphragm 94 like wise reverses (e.g., inward). Thus, voice coil 12 and attached conical diaphragm 94 are caused to move in a piston-like motion at frequencies corresponding to the frequency of the alternating current input to voice coil 12.
Field structure 87 and edge 104 are connected to and supported by one piece frame structure 105 with back basket 102. In typical operation of dome with annular concentric section system 101 is similar to above mentioned conical loudspeaker.
Diaphragm 100 is supported at its periphery by an outer suspension system 95. Outer suspension system 95 is also commonly called an “edge.” Field structure 87 and edge 95 are connected to and supported by appropriate frame structure 97.
In typical operation, when an acoustic wave is applied to diaphragm 100, a corresponding reciprocal piston-like motion indicated by arrow 98 of the voice coil generates an electric signal at frequencies corresponding to the frequency of the acoustic wave.
It will be apparent that various changes may be made in the shape of the acoustic diaphragm, not only the circular but also oval, as shown in
Because of symmetry of the ears and helical component in sound waves caused by an acoustic element, symmetric arrangements for the helix of acoustic elements, 107a and 107b in
It is believed that the improved acoustic diaphragm and resulting improved electric to acoustic and acoustic to electric transducer systems of present invention and many of their attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit or scope of the invention or sacrificing all of the material advantages, the forms herein above described being merely preferred or exemplary embodiments thereof.
This application claims priority to U.S. Provisional application No. 60/586,065, filed Jul. 7, 2004.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1757451 | Crane | May 1930 | A |
| 4146744 | Veranth | Mar 1979 | A |
| 20020027040 | Sato et al. | Mar 2002 | A1 |
| Number | Date | Country |
|---|---|---|
| 191405038 | Feb 1915 | GB |
| 5324812 | Jul 1976 | JP |
| 56019298 | Feb 1981 | JP |
| 58-108896 | Jun 1983 | JP |
| 58108896 | Jun 1983 | JP |
| 58127499 | Jul 1983 | JP |
| 60007299 | Jan 1985 | JP |
| 60083497 | May 1985 | JP |
| 61009098 | Jan 1986 | JP |
| 62-149296 | Jul 1987 | JP |
| 01037199 | Feb 1989 | JP |
| 1037199 | Feb 1989 | JP |
| 8140183 | May 1996 | JP |
| 9224297 | Aug 1997 | JP |
| 11215589 | Aug 1999 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20090129624 A1 | May 2009 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60586065 | Jul 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11039204 | Jan 2005 | US |
| Child | 12230778 | US |
