CA1131132A - Diaphragm for a loudspeaker - Google Patents
Diaphragm for a loudspeakerInfo
- Publication number
- CA1131132A CA1131132A CA384,757A CA384757A CA1131132A CA 1131132 A CA1131132 A CA 1131132A CA 384757 A CA384757 A CA 384757A CA 1131132 A CA1131132 A CA 1131132A
- Authority
- CA
- Canada
- Prior art keywords
- diaphragm
- core member
- loudspeaker
- front surface
- cover member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Diaphragms For Electromechanical Transducers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A diaphragm for a loudspeaker includes a core member having a flat front surface from which a frustum-shaped side sur-face extends to a back portion, a cover member secured to the back portion and adapted to be connected to a voice coil bobbin of the loudspeaker, an outer radiation layer mounted on the front surface and having a relatively high resonance sharpness, and an intermediate layer laminated between the front surface and the outer radiation layer and having a resonance sharpness lower than that of the outer radiation layer.
A diaphragm for a loudspeaker includes a core member having a flat front surface from which a frustum-shaped side sur-face extends to a back portion, a cover member secured to the back portion and adapted to be connected to a voice coil bobbin of the loudspeaker, an outer radiation layer mounted on the front surface and having a relatively high resonance sharpness, and an intermediate layer laminated between the front surface and the outer radiation layer and having a resonance sharpness lower than that of the outer radiation layer.
Description
1~31~32 BACKGROUND OF THE INVENTION
This invention relates generally to a diaphragm for a loudspeaker and, more particularly, to a loudspeaker diaphragm provided with a core member which is made from a foamed resin material molded into a frustum configuration.
Diaphragms for use in loudspeakers are known in which a foamed resin material, such as foaming polystyrene, is molded generally into a frusto-conical configuration to be used for the core member of the diaphragm. Such diaphragms typically have the same mass as conventional diaphragms of paper and the like which are also molded into a frusto-conical configuration.
Although these foamed core members provided certain advantages over conventional paper core members, for example, hindering the formation of a split vibration and improving the acoustic characteristics thereof, they disadvantageously have a low vibration or acoustic propagation speed and a relatively low natural resonance frequency, while retaining a high resonance sharpness Q. Thus, the acoustic output-frequency characteristic of the foamed diaphragms have a remarkable peak dip, particularly in the high-pitched tone region, and do not establish a satis-factory flat response.
The foamed diaphragm usually has its back or small-diameter portion connected to a voice coil bobbin and is driven thereby. However, the distance between the back or small-diameter end portion and the flat front surface of the frustum at its cen-ter differs from the distance between the back portion and the front surface at the periphery of the latter, resulting in a ~131132 degrada-ion of the phase cha~acteristic of the acouctic output.
Further, since the voice coil bobbin is adhesively affixed direct-ly to the back end of the foamed core member, it is difficult to maintain the bobbin in a fixed condition with any satisfactory degree of accuracy, and the resulting movement with res?ect to the adhesively fixed condition affects the acoustic output-frequency characteristic in the high-pitched tone region.
Furthermore, since the foamed resin material has a generally poor heat resistance, it is difficult to use such material in a diaphragm of a large output speaker because of the large amount of heat transferred from the bobbin to the core mem-ber.
OBJECTS A~ID SUr.~MARY OF THE INVENTION
Accordingly, it is an object of this invention to pro-vide a diaphragm for a loudspeaker that avoids the above-described difficulties encountered with the prior art.
More particularly, it is an object of this invention to provide a diaphragm for a loudspeaker which is constructed to give a substantially flat response to the acoustic output-frequency characteristic in the high-pitched tone region.
It is another object of this invention to provide a diaphragm for a loudspeaker which reduces the peak dip of the acoustic output-frequency characteristic in the high-pitched tone reglon .
It is a further object of this invention to provide a diaphragm for a loudspeaker which maintains the voice coil bobbin and core member of the diaphravm in an accurately aligned and securely coupled condition.
~3~3;~
It is still a further object of this invention to provide a diaphragm for a loudspeaker with improved heat resistant properties for application to large output loudspeakers.
In accordance with an aspect of this invention, a diaphragm for a loudspeaker comprises a frustum-shaped core member having a flat front surface, an outer radiation layer mounted on the front surface and having a high resonance sharpness, and an intermediate layer interposed between the front core surface and the outer radiation layer and having a resonance sharpness lower than that of the outer radiation layer. Further, the core member has an exterior surface which tapers from its front surface to the back end portion of the core member, and the diaphragm further includes a cover member connected to the back portion and adapted to be connected to the voice coil bobbin of the loudspeaker.
More particularly, there is provided:
A diaphragm for a loudspeaker comprising:
a frustum-shaped core member having a front surface, said core member including a first peripheral section having a central hollow portion and a tapered exterior surface, and a second center section which conforms in shape to said central hollow portion, said sections being integrated with each other so as to form said front surface; and an outer radiation layer mounted on said front surface and having a high resonance sharpness.
~3~13Z
The above, and other, objects, features and advantages of the invention, will be apparent in the following detailed description of the illustrative embodiment of the invention which is to be read in connection with the accompanying drawings.
BRIEF DESCP~IPTION OF THE DRA~TINGS
Fig. 1 is a cross-sectional view of a diaphragm for a loudspeaker according to an embodiment of this invention;
Fig. 2 an enlar~ed fragmentary cross-sectional view of a peripheral portion of the diaphragm of Fig. 1, and showing details of the attachment of an edge member attached thereto;
Fig. 3 is an enlarged fragmentary cross-sectional view of a back end portion of the diaphragm of Fig. 1, and particularly showing its connection to the voice coil bobbin of the loudspeaker;
-4a-31~32, Fig. 4A is a graphical representation of the acoustic output-frequency characteristic of a conventional diaphragm;
Fig. 4B is a graphical representation similar to that of Fig. 4A, but illustrating the acoustic output-frequency charac-teristic of a conventional diaphragm having an outer radiation layer;
Fig. 4C is a graphical representation illustrating the acoustic output-frequency characteristic of a diaphragm according to an embodiment of this invention; and Fig. 4D is a graphical representationi, comparing the acoustic output-frequency characteristic of a conventional dia-phragm with that of a similar diaphragm having a cover member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in detail, and initially to Fig. 1 thereof, a diaphragm 10 for a loudspeaker according to an embodiment of this invention is shown to be comprised of a core member 11 molded generally into a frustum or frusto-conical con-figuration, an outer radiation layer 12 having a relatively high resonance sharpness Q and an intermediate layer 13 interposed between core member 11 and outer radiation layer 12 and having a resonance sharpness Q lower t~an that of outer radiation layer 12.
Preferably, core member 11 is composed of a foamed resin material, such as foaming polystyrene or the like, outer radiation layer 12 is made from a sheet of polyester, vinyl chloride or the like, having an approximate thickness of 100 mm, and intermediate layer 13 is composed of foaming butyl rubber, sponge or like material, having a thickness of approximately l mm.
~13~13~
As shown in Fig. 1, core member 11 is divided into two sections, that is, a peripheral or outer section lla having a cen-tral hollow portion into which there is fitted a center section 11_, in order that the diaphragm may be more easily produced.
Sections lla and 11_ are integrated with each other such that center section llb conforms in shape to the central hollow por-tion of peripheral section lla and such that the sections together fol~n a continuous flat front surface llc which has intermediate l~ver 13 and outer radiation layer 12 laminated thereon. An edge member 14 may be connected to diaphragm lG by sandwiching a portion thereof between intermediate layer 13 and surface llc, as shown in Fig. 2.
Referring to Fig. 3, it will be seen that peripheral section lla is formed, at its back end portion lld, with a circum-ferential flange lle which projects inwardly, and center section 11_ is stepped at its back end llf so as to form a circumferential or annular stepped or cut-out portion 11~ in communication with the central hollow portion of peripheral section lla.
Further, diaphragm 10 includes a cover member 15 of a unitary or laminated lightweight, rigid material, for example, a punched metal or mesh material, such as, aluminum, magnesium, titanium, beryllium, boron, or the like, which covers an area of back portion lld of core member 11. Cover me~lber 15 is shown to be comprised of a first flaring portion 15a adhesively secured to, and covering the peripheral tapered surface of core member 11 and a second cylindrical portion 15_ shaped to extend closely through the hole defined by circumferential flange lle. The free edge portion 15c of cylindrical portion 15_ is outwardly swaged, as ~1311~2 shown, to embrace flan~e lle and thereby further secure cover member 15 to core number 11. As shown in Fig. l, the distance La between the edge 15d of first portion 15a and the peripheral edge of the acoustic output or radiation surface lOa of the dia-phragm, that is, of outer radiation layer 12, is approximately equal to the distance Lb between the edge 15c of second portion 15_ and continuous front surface llc of core member 11, taken along the inner surface of peripheral section lla, in order that a satisfactory phase characteristic can be obtained for the diaphragm.
Diaphragm 10 is provided with a voice coil bobbin 16 would with a voice coil 17 of the same type used in conventional loudspeakers, and one end of voice coil bobbin 16 is inserted into a recess defined by cylindrical portion 15_ of cover member 15, the inner surface of peripheral section lla and the stepped or cut-out portion llg of center section llb, and is fixedly secured to cover member 15 by a suitable adhesive, as at 18. In constructing the diaphragm, it is preferable and more efficient to adhere voice coil bobbin 16 to cover member 15 before center section ll_ is inserted into and integrated with peripheral section lla of the core ll.
As shown in Fig. l, the loudspeaker is further supplied with a magnetic circuit l9 having a magnetic gap l9a in which voice coil 17 is disposed, whereby diaphragm 10 is driven by elec-tric input signals applied to voice coil 17. The location of voice coil bobbin 16 is regulated by a damper member 20, which is secured to a frame (not shown), along with edge member 14 and magnetic circuit l9.
~L~ 3113~
In the above-described embodiTnent of this invention, the split vibration frequency of the primary mode of core member 11 can be raised to a higher frequency by mounting thereon the outer radiation layer 12 which has a relatively high resonance sharpness Q. Further, the resonance sharpness Q of core member 11 can be reduced by mounting intermediate layer 13 between con-tinuous surface llc and layer 12, with such intermediate layer 13 having a resonance sharpness Q lower than that of outer radiation layer 12 so as to provide a desired internal loss. By reason of the foregoing, a relatively flat response is obtained by reducing the peak dip of the acoustic output-frequency characteristic, particularly in the high-pitched tone region.
More particularly, the acoustic output-frequency charac-teristic of a loudspeaker using a conventional diaphragm is shown in Fig. 4A. There is some improvement in the acoustic output-frequency characteristic of a diaphragm when only an outer radia-tion layer 12 of a vinyl chloride material is adhered to the sur-face llc of core member 11 (without the intermediate layer 13).
Such improvement is realized particularly in respect to the rise in the split vibration frequency of the primary mode and a slight reduction in the peak dip of the acoustic output-frequency charac-teristic, as shown in Fig. 4B. However, with the addition of outer skin layer 12 alone, a sufficiently flat response is still not obtained. Further, alteration of the thickness and material of outer radiation layer 12 may have an undesired effect on the ad-hesive property of the core member without bringing about an effective change in the acoustic output-frequency characteristic.
In the embodiment of the diaphragm according to this ~31~L32 invention, in which intermediate layer 13 is made from a butyl rubber sheet with a resonance sharpness Q less than one-fifth of that of outer radiation layer 12 and is interposed between core member 11 and outer radiation layer 12, the acoustic output-frequency characteristic is substantially improved or flattened, particularly in the high-pitched tone region from lKHz to5KHz.
It has been found that, by proper selection of the materials and properties of outer radiation layer 12 and intermediate layer 13, the acoustic output-frequency characterisitc can be controlled over a wide range thereof. On the other hand, it has been found that the type of adhesive used for connecting outer radiation layer 12, intermediate layer 13, and core member 11 does not have a major effect on the acoustic output-frequency characteristic of the loudspeaker.
The diaphragms which are the subject of the characteris-tics shown on Figs. 4A to 4C each had a cover member 15 secured to the core member of each diaphragm. It is to be noted that, with voice coil bobbin 16 adhesively fixed to cover member 15, the accuracy of alignment and connection of bobbin 16 to the diaphragm is improved so as to provide a diaphragm with a more uniform acoustic output-frequency characteristic than is obtained when bobbin 16 is directly adhered to the foamed resin material of core member 11. Further, since heat produced in voice coil 17 can be radiated from diaphragm 10 through cover member 15 adhered to core member 11, the heat resistance is improved so as to permit production of a large acoustic output. Also, since core member 11 is made from a foamed resin material and is driven through cover member lS, which is made of a light and rigid material, any _9_ ~3113Z
adverse effect on the acoustic output-frequency characteristic caused by the natural vibrations of core member 11, can be reduced.
Further, since the previously described distances La and Lb are made to be approximately equal, the acoustic subject of the dia-phragm can be provided with a satisfactory phase characteristic.
As shown in the acoustic output-frequency graph Fig. 4D, the use of cover member 15 can effectively raise the resonance frequency in the high-pitched tone region by about 3000Hz, while, at the same, reducing the peak dip in the same re~ion to provide a relatively more satisfactory acoustic output-frequency charac-teristic. In Fig. 4D, the broken line illustrates the characteristi of a conventional diaphragm having a core member 11 of foaming polystyrene directly connected to bobbin 16, and the solid line illustrates the characteristic of the same diaphragm merely pro-vided with cover member 15. In other words, both diaphragms represented by Fig. 4D do not have outer radiation layer 12 and intermediate layer 13 laminated thereon. Therefore, Fig. 4D shows only the effect of cover member 15.
Having described a specific embodiment of the invention with reference to the accompanying drawings, it is to be under-stood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
This invention relates generally to a diaphragm for a loudspeaker and, more particularly, to a loudspeaker diaphragm provided with a core member which is made from a foamed resin material molded into a frustum configuration.
Diaphragms for use in loudspeakers are known in which a foamed resin material, such as foaming polystyrene, is molded generally into a frusto-conical configuration to be used for the core member of the diaphragm. Such diaphragms typically have the same mass as conventional diaphragms of paper and the like which are also molded into a frusto-conical configuration.
Although these foamed core members provided certain advantages over conventional paper core members, for example, hindering the formation of a split vibration and improving the acoustic characteristics thereof, they disadvantageously have a low vibration or acoustic propagation speed and a relatively low natural resonance frequency, while retaining a high resonance sharpness Q. Thus, the acoustic output-frequency characteristic of the foamed diaphragms have a remarkable peak dip, particularly in the high-pitched tone region, and do not establish a satis-factory flat response.
The foamed diaphragm usually has its back or small-diameter portion connected to a voice coil bobbin and is driven thereby. However, the distance between the back or small-diameter end portion and the flat front surface of the frustum at its cen-ter differs from the distance between the back portion and the front surface at the periphery of the latter, resulting in a ~131132 degrada-ion of the phase cha~acteristic of the acouctic output.
Further, since the voice coil bobbin is adhesively affixed direct-ly to the back end of the foamed core member, it is difficult to maintain the bobbin in a fixed condition with any satisfactory degree of accuracy, and the resulting movement with res?ect to the adhesively fixed condition affects the acoustic output-frequency characteristic in the high-pitched tone region.
Furthermore, since the foamed resin material has a generally poor heat resistance, it is difficult to use such material in a diaphragm of a large output speaker because of the large amount of heat transferred from the bobbin to the core mem-ber.
OBJECTS A~ID SUr.~MARY OF THE INVENTION
Accordingly, it is an object of this invention to pro-vide a diaphragm for a loudspeaker that avoids the above-described difficulties encountered with the prior art.
More particularly, it is an object of this invention to provide a diaphragm for a loudspeaker which is constructed to give a substantially flat response to the acoustic output-frequency characteristic in the high-pitched tone region.
It is another object of this invention to provide a diaphragm for a loudspeaker which reduces the peak dip of the acoustic output-frequency characteristic in the high-pitched tone reglon .
It is a further object of this invention to provide a diaphragm for a loudspeaker which maintains the voice coil bobbin and core member of the diaphravm in an accurately aligned and securely coupled condition.
~3~3;~
It is still a further object of this invention to provide a diaphragm for a loudspeaker with improved heat resistant properties for application to large output loudspeakers.
In accordance with an aspect of this invention, a diaphragm for a loudspeaker comprises a frustum-shaped core member having a flat front surface, an outer radiation layer mounted on the front surface and having a high resonance sharpness, and an intermediate layer interposed between the front core surface and the outer radiation layer and having a resonance sharpness lower than that of the outer radiation layer. Further, the core member has an exterior surface which tapers from its front surface to the back end portion of the core member, and the diaphragm further includes a cover member connected to the back portion and adapted to be connected to the voice coil bobbin of the loudspeaker.
More particularly, there is provided:
A diaphragm for a loudspeaker comprising:
a frustum-shaped core member having a front surface, said core member including a first peripheral section having a central hollow portion and a tapered exterior surface, and a second center section which conforms in shape to said central hollow portion, said sections being integrated with each other so as to form said front surface; and an outer radiation layer mounted on said front surface and having a high resonance sharpness.
~3~13Z
The above, and other, objects, features and advantages of the invention, will be apparent in the following detailed description of the illustrative embodiment of the invention which is to be read in connection with the accompanying drawings.
BRIEF DESCP~IPTION OF THE DRA~TINGS
Fig. 1 is a cross-sectional view of a diaphragm for a loudspeaker according to an embodiment of this invention;
Fig. 2 an enlar~ed fragmentary cross-sectional view of a peripheral portion of the diaphragm of Fig. 1, and showing details of the attachment of an edge member attached thereto;
Fig. 3 is an enlarged fragmentary cross-sectional view of a back end portion of the diaphragm of Fig. 1, and particularly showing its connection to the voice coil bobbin of the loudspeaker;
-4a-31~32, Fig. 4A is a graphical representation of the acoustic output-frequency characteristic of a conventional diaphragm;
Fig. 4B is a graphical representation similar to that of Fig. 4A, but illustrating the acoustic output-frequency charac-teristic of a conventional diaphragm having an outer radiation layer;
Fig. 4C is a graphical representation illustrating the acoustic output-frequency characteristic of a diaphragm according to an embodiment of this invention; and Fig. 4D is a graphical representationi, comparing the acoustic output-frequency characteristic of a conventional dia-phragm with that of a similar diaphragm having a cover member.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in detail, and initially to Fig. 1 thereof, a diaphragm 10 for a loudspeaker according to an embodiment of this invention is shown to be comprised of a core member 11 molded generally into a frustum or frusto-conical con-figuration, an outer radiation layer 12 having a relatively high resonance sharpness Q and an intermediate layer 13 interposed between core member 11 and outer radiation layer 12 and having a resonance sharpness Q lower t~an that of outer radiation layer 12.
Preferably, core member 11 is composed of a foamed resin material, such as foaming polystyrene or the like, outer radiation layer 12 is made from a sheet of polyester, vinyl chloride or the like, having an approximate thickness of 100 mm, and intermediate layer 13 is composed of foaming butyl rubber, sponge or like material, having a thickness of approximately l mm.
~13~13~
As shown in Fig. 1, core member 11 is divided into two sections, that is, a peripheral or outer section lla having a cen-tral hollow portion into which there is fitted a center section 11_, in order that the diaphragm may be more easily produced.
Sections lla and 11_ are integrated with each other such that center section llb conforms in shape to the central hollow por-tion of peripheral section lla and such that the sections together fol~n a continuous flat front surface llc which has intermediate l~ver 13 and outer radiation layer 12 laminated thereon. An edge member 14 may be connected to diaphragm lG by sandwiching a portion thereof between intermediate layer 13 and surface llc, as shown in Fig. 2.
Referring to Fig. 3, it will be seen that peripheral section lla is formed, at its back end portion lld, with a circum-ferential flange lle which projects inwardly, and center section 11_ is stepped at its back end llf so as to form a circumferential or annular stepped or cut-out portion 11~ in communication with the central hollow portion of peripheral section lla.
Further, diaphragm 10 includes a cover member 15 of a unitary or laminated lightweight, rigid material, for example, a punched metal or mesh material, such as, aluminum, magnesium, titanium, beryllium, boron, or the like, which covers an area of back portion lld of core member 11. Cover me~lber 15 is shown to be comprised of a first flaring portion 15a adhesively secured to, and covering the peripheral tapered surface of core member 11 and a second cylindrical portion 15_ shaped to extend closely through the hole defined by circumferential flange lle. The free edge portion 15c of cylindrical portion 15_ is outwardly swaged, as ~1311~2 shown, to embrace flan~e lle and thereby further secure cover member 15 to core number 11. As shown in Fig. l, the distance La between the edge 15d of first portion 15a and the peripheral edge of the acoustic output or radiation surface lOa of the dia-phragm, that is, of outer radiation layer 12, is approximately equal to the distance Lb between the edge 15c of second portion 15_ and continuous front surface llc of core member 11, taken along the inner surface of peripheral section lla, in order that a satisfactory phase characteristic can be obtained for the diaphragm.
Diaphragm 10 is provided with a voice coil bobbin 16 would with a voice coil 17 of the same type used in conventional loudspeakers, and one end of voice coil bobbin 16 is inserted into a recess defined by cylindrical portion 15_ of cover member 15, the inner surface of peripheral section lla and the stepped or cut-out portion llg of center section llb, and is fixedly secured to cover member 15 by a suitable adhesive, as at 18. In constructing the diaphragm, it is preferable and more efficient to adhere voice coil bobbin 16 to cover member 15 before center section ll_ is inserted into and integrated with peripheral section lla of the core ll.
As shown in Fig. l, the loudspeaker is further supplied with a magnetic circuit l9 having a magnetic gap l9a in which voice coil 17 is disposed, whereby diaphragm 10 is driven by elec-tric input signals applied to voice coil 17. The location of voice coil bobbin 16 is regulated by a damper member 20, which is secured to a frame (not shown), along with edge member 14 and magnetic circuit l9.
~L~ 3113~
In the above-described embodiTnent of this invention, the split vibration frequency of the primary mode of core member 11 can be raised to a higher frequency by mounting thereon the outer radiation layer 12 which has a relatively high resonance sharpness Q. Further, the resonance sharpness Q of core member 11 can be reduced by mounting intermediate layer 13 between con-tinuous surface llc and layer 12, with such intermediate layer 13 having a resonance sharpness Q lower than that of outer radiation layer 12 so as to provide a desired internal loss. By reason of the foregoing, a relatively flat response is obtained by reducing the peak dip of the acoustic output-frequency characteristic, particularly in the high-pitched tone region.
More particularly, the acoustic output-frequency charac-teristic of a loudspeaker using a conventional diaphragm is shown in Fig. 4A. There is some improvement in the acoustic output-frequency characteristic of a diaphragm when only an outer radia-tion layer 12 of a vinyl chloride material is adhered to the sur-face llc of core member 11 (without the intermediate layer 13).
Such improvement is realized particularly in respect to the rise in the split vibration frequency of the primary mode and a slight reduction in the peak dip of the acoustic output-frequency charac-teristic, as shown in Fig. 4B. However, with the addition of outer skin layer 12 alone, a sufficiently flat response is still not obtained. Further, alteration of the thickness and material of outer radiation layer 12 may have an undesired effect on the ad-hesive property of the core member without bringing about an effective change in the acoustic output-frequency characteristic.
In the embodiment of the diaphragm according to this ~31~L32 invention, in which intermediate layer 13 is made from a butyl rubber sheet with a resonance sharpness Q less than one-fifth of that of outer radiation layer 12 and is interposed between core member 11 and outer radiation layer 12, the acoustic output-frequency characteristic is substantially improved or flattened, particularly in the high-pitched tone region from lKHz to5KHz.
It has been found that, by proper selection of the materials and properties of outer radiation layer 12 and intermediate layer 13, the acoustic output-frequency characterisitc can be controlled over a wide range thereof. On the other hand, it has been found that the type of adhesive used for connecting outer radiation layer 12, intermediate layer 13, and core member 11 does not have a major effect on the acoustic output-frequency characteristic of the loudspeaker.
The diaphragms which are the subject of the characteris-tics shown on Figs. 4A to 4C each had a cover member 15 secured to the core member of each diaphragm. It is to be noted that, with voice coil bobbin 16 adhesively fixed to cover member 15, the accuracy of alignment and connection of bobbin 16 to the diaphragm is improved so as to provide a diaphragm with a more uniform acoustic output-frequency characteristic than is obtained when bobbin 16 is directly adhered to the foamed resin material of core member 11. Further, since heat produced in voice coil 17 can be radiated from diaphragm 10 through cover member 15 adhered to core member 11, the heat resistance is improved so as to permit production of a large acoustic output. Also, since core member 11 is made from a foamed resin material and is driven through cover member lS, which is made of a light and rigid material, any _9_ ~3113Z
adverse effect on the acoustic output-frequency characteristic caused by the natural vibrations of core member 11, can be reduced.
Further, since the previously described distances La and Lb are made to be approximately equal, the acoustic subject of the dia-phragm can be provided with a satisfactory phase characteristic.
As shown in the acoustic output-frequency graph Fig. 4D, the use of cover member 15 can effectively raise the resonance frequency in the high-pitched tone region by about 3000Hz, while, at the same, reducing the peak dip in the same re~ion to provide a relatively more satisfactory acoustic output-frequency charac-teristic. In Fig. 4D, the broken line illustrates the characteristi of a conventional diaphragm having a core member 11 of foaming polystyrene directly connected to bobbin 16, and the solid line illustrates the characteristic of the same diaphragm merely pro-vided with cover member 15. In other words, both diaphragms represented by Fig. 4D do not have outer radiation layer 12 and intermediate layer 13 laminated thereon. Therefore, Fig. 4D shows only the effect of cover member 15.
Having described a specific embodiment of the invention with reference to the accompanying drawings, it is to be under-stood that the invention is not limited to that precise embodiment, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A diaphragm for a loudspeaker comprising:
a frustum-shaped core member having a front surface, said core member including a first peripheral section having a central hollow portion and a tapered exterior surface, and a second center section which conforms in shape to said central hollow portion, said sections being integrated with each other so as to form said front surface
a frustum-shaped core member having a front surface, said core member including a first peripheral section having a central hollow portion and a tapered exterior surface, and a second center section which conforms in shape to said central hollow portion, said sections being integrated with each other so as to form said front surface
2. A diaphragm according to Claim l; in which said first section includes an inwardly directed flange and said second section in-cludes a cut-out portion in communication with said central hollow portion.
3. A diaphragm according to Claim 2; further comprising a cover member connected to said first peripheral section and covering said flange and a portion of said tapered exterior surface.
4, A diaphragm for a loudspeaker according to Claim 3; in which said loudspeaker includes a voice coil bobbin connected to said cover member.
5. A diaphragm according to Claim 4; in which said core member has a recess therein defined by said cover member, said central hollow portion and said cut-out portion, and said bobbin is dispose within said recess.
6. A diaphragm according to Claim 3; in which said cover member has a first edge at its connection to said flange member and a second edge along said exterior tapered surface, and the distance from said first edge to said front surface, at the mating of said peripheral section with said center section, is substantially equal to the distance from said second edge to a peripheral edge of said outer radiation layer.
7. A diaphragm according to Claim 1 in which said loudspeaker includes a voice coil bobbin coupled to said core member and wherein said core member has a continuous flat surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA384,757A CA1131132A (en) | 1978-08-18 | 1981-08-27 | Diaphragm for a loudspeaker |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP100003/78 | 1978-08-18 | ||
| JP10000378A JPS5527702A (en) | 1978-08-18 | 1978-08-18 | Vibrator for speaker |
| CA334,005A CA1124654A (en) | 1978-08-18 | 1979-08-17 | Diaphragm for a loudspeaker |
| CA384,757A CA1131132A (en) | 1978-08-18 | 1981-08-27 | Diaphragm for a loudspeaker |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1131132A true CA1131132A (en) | 1982-09-07 |
Family
ID=27166368
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA384,757A Expired CA1131132A (en) | 1978-08-18 | 1981-08-27 | Diaphragm for a loudspeaker |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1131132A (en) |
-
1981
- 1981-08-27 CA CA384,757A patent/CA1131132A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |