CA1196717A - Loudspeaker enclosure arrangement for voice communication terminals - Google Patents
Loudspeaker enclosure arrangement for voice communication terminalsInfo
- Publication number
- CA1196717A CA1196717A CA000430527A CA430527A CA1196717A CA 1196717 A CA1196717 A CA 1196717A CA 000430527 A CA000430527 A CA 000430527A CA 430527 A CA430527 A CA 430527A CA 1196717 A CA1196717 A CA 1196717A
- Authority
- CA
- Canada
- Prior art keywords
- enclosure
- loudspeaker
- foam material
- peripheral edge
- spider
- 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
Links
- 238000004891 communication Methods 0.000 title claims abstract description 15
- 239000006261 foam material Substances 0.000 claims abstract description 39
- 241000239290 Araneae Species 0.000 claims abstract description 22
- 230000002093 peripheral effect Effects 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 15
- 230000008878 coupling Effects 0.000 claims description 8
- 238000010168 coupling process Methods 0.000 claims description 8
- 238000005859 coupling reaction Methods 0.000 claims description 8
- 230000000295 complement effect Effects 0.000 claims description 4
- 230000003993 interaction Effects 0.000 claims 3
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 claims 1
- 230000000694 effects Effects 0.000 description 4
- 229920003023 plastic Polymers 0.000 description 4
- 239000004033 plastic Substances 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 239000006260 foam Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229920002379 silicone rubber Polymers 0.000 description 2
- 239000004945 silicone rubber Substances 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 239000003973 paint Substances 0.000 description 1
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- 229920001084 poly(chloroprene) Polymers 0.000 description 1
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- 238000007493 shaping process Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000002966 varnish Substances 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
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
- H04R1/2807—Enclosures comprising vibrating or resonating arrangements
- H04R1/283—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm
- H04R1/2834—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm for loudspeaker transducers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
Landscapes
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Telephone Set Structure (AREA)
- Details Of Audible-Bandwidth Transducers (AREA)
Abstract
LOUDSPEAKER ENCLOSURE ARRANGEMENT FOR VOICE COMMUNICATION TERMINALS
Abstract of the Disclosure The invention provides an enclosure arrangement for a loudspeaker adapted to be mounted in a voice communication terminal. The invention provides primary and secondary enclosures for the loudspeaker.
The primary enclosure comprises a piece of resilient open cell foam material having one face provided with a concavity suitable for receiving the spider and the voice coil structure of the loudspeaker. The peripheral edge of the one face of the foam material is secured to the peripheral edge of the spider and the outer surface of the foam material has a flexible layer of substantially air-impermeable material, whereby the loudspeaker is provided with an attached flexible enclosure. The secondary enclosure comprises the housing in which the loudspeaker is mounted. The flexibility of the primary enclosure allows energy to be coupled between itself and the secondary enclosure.
-i-
Abstract of the Disclosure The invention provides an enclosure arrangement for a loudspeaker adapted to be mounted in a voice communication terminal. The invention provides primary and secondary enclosures for the loudspeaker.
The primary enclosure comprises a piece of resilient open cell foam material having one face provided with a concavity suitable for receiving the spider and the voice coil structure of the loudspeaker. The peripheral edge of the one face of the foam material is secured to the peripheral edge of the spider and the outer surface of the foam material has a flexible layer of substantially air-impermeable material, whereby the loudspeaker is provided with an attached flexible enclosure. The secondary enclosure comprises the housing in which the loudspeaker is mounted. The flexibility of the primary enclosure allows energy to be coupled between itself and the secondary enclosure.
-i-
Description
3L~9~ ~ 7 The present invention relates generally to sound translating devices and more particularly to loudspeaker enclosure arrangements for use in voice communication terminals.
A loudspeaker consists of a voice coil or motor unit operating an acoustic conical diaphragm, one side of which acts on an enclosed space known as the loudspeaker enclosure. Since the enclosure provides an acoustical load on the diaphragm, the operating characteristics of a loudspeaker are influenced by the acous-tical properties of the enclosure. Throuyh the years, very substantial efforts have been directed towards the design of enclosures for the best possible reproduction of sound, especially for so-called high-fidelity equipment.
In the past few years, it has become increasingly common to provide telecommunication equipment and in particular, telephone equipment, with the capability for hands-free voice communication.
Similarly, combined voice/data advanced telecommunication terminals such as Displayphone (trademark of Northern Telecom) also use a loudspeaker to provide hands-free voice communication.
However, a number of problems are associated with this development. In the first place, the loudspeakers are usually mounted on an inside surface of the housing, often in a cramped location, and -the entire unit including a variety of electronic circuitry therefore becomes a haphazard enclosure for the loudspeaker. Secondly, since this type of equipment is meant to provide only voice communication as opposed to high-fidelity music and since manufac-turers find it desirable to minimize the cost and size of their equipment, the loudspeaker employed therein tends to be an inexpensive minia-ture unit having an acceptable frequency response only in the voice frequency ranye.
'7 Contributors to the marginal quality of sound produced by such loudspeaker arrangements reside in the lack of proper enclosure an(l in the effect of loudspeaker cone resonance which results in ti~e unit generating excessive acoustic output near the lower end of the voice frequency spectrum. Of course, the solution to this problem through the use of a custom designed enclosure is entirely feasible but prohibitively expensive.
There have been attempts in the past directed at the modification of a loudspeaker's output performance without mounting it in a proper enclosure. For example, United States patent No. 3,833,085 describes a low-frequency loudspeaker wherein the tendency to provide excessive midrange acoustic output was solved by providing ~he speaker with a circular disk of neoprene rubber mounted inside its conical diaphragm. The disk is attached adhesively at its periphery to the diaphragm at a circle spaced inwardly from the outer periphery of the diaphragm and at its center to the support dome for the loudspeaker.
Another method of modifying loudspeaker output response is described in United States patent No. 3,324,966 which discloses the combination of a loudspeaker and a pseudo-enclosure comprising a pair of sound absorbing chambers interconnected by a valving arrangement in the form of a narrow channel.
Yet another method of providing an enclosure for a loudspeaker is described in United States patent No. 3,720,285. The purpose of this device was to replace the absorbent material, such as glass fiber9 which is often used in enclosures. The patent provides an enclosure comprised of a rigid foamed plastic material which is moulded around a loudspeaker. On curing, the skin of the plastic seals the enclosure to provide a rigid self-contained enclosure, In addition to the practical manufacturing problems associated with such a device, the resultant enclosure increases the low resonant frequency of the loudspeaker. That is precisely the opposite of what the present invention achieves.
As effective as these prior art devices may be for their intended purpose, they represent inadequate, expensive and complex solutions to the problem at hand. I-t is thereFore an object of this invention to provide an economical and simple solution to the problem of shaping the frequency response of a miniature loudspeaker for use in voice communication terminalsO
In accordance with the invention, there is provided an electro-acoustic transducer for use in voice communication terminals adapted to receive voice frequency signals. A small loudspeaker has a voice coil structure and a conical diaphragm supported by a spider having a peripheral ed~e defining the shape of the loudspeaker. A piece of resilient open cell foam material having a shape complementary similar to that of the loudspeaker has one face provided with a concavity suitable for receiving the spider and the voice coil structure. The edge of the foam material is secured to the peripheral edge of the spider and the outer surface of the foam material is covered with a flexible layer of substantially air-impermeable material thereby providing the loudspeaker with an attached flexible back cavity enclosure.
It is also an object of the invention to provide loudspeakers used in voice communication terminals with an improved enclosure arrangement. This is achieved by providing the loudspeaker with a primary enclosure which comprises an attached flexible enclosure and a 7 ~
secondary enclosure which consists of -the terminal housing. The flexible enclosure is effective to smooth out the frequency response and to remove the low frequency peak due to the resonant frequency of the loudspeaker.
This is achieved without unduly affecting the normal low frequency response of the loudspeaker.
The invention therefore provides an economical enclosure arrangement for a piece of telecornmunication equipment wherein the response peak due to the resonant frequency of the loudspeaker is substantially eliminated and in which the overall frequency response is irnproved. Since the enclosure is small and flexible, the unit may be fitted in a cramped location of a piece of equipment. In addition, the loudspeaker will operate acceptably even if a portion of the flexible enclosure is deformed slightly against an adjacent component or if the enclosure is shaped to match its mounting space.
An example embodiment of the invention will now be described -in conjunction with the drawings in which:
Figure 1 is a partly sectional view of an electro-acoustic transducer in accordance with the invention;
Figure 2 is a graphical diagram illustrating a typical fre~uency response for the transducer of figure 1; and Figure 3 is a side view, partly in cross-section, of an enclosure arrangement in accordance with the invention.
Figure 1 shows a miniature loudspeaker 10 including a voice coil structure 11, and a spider 12 supporting a conical acoustic diaphragm 13. Such loudspeakers are available as commercial off-the-shelf iterns and may be circular or rectangular in shape. Common nominal sizes for these loudspeakers are about 21 inches in diameter or 21 inches by 3 inches. A
peripheral edge 14 oF the spider 12 defines the perimeter and shape of the loudspeaker 10.
Shown in cross-section is a piece of flexible foam material 15 having an open cell or air-permeable construction. The foam material has a shape complementary similar to that of the loudspeaker; that is, it is either circular or rectangular and is provided with an opening at its approximate geornetrical center as well as a conical depression to allow close-fitting engagement with the voice coil structure 11 and the spider 12. For a circular loudspeaker, the foam material is thus somewhat donut-shaped. Of course, it should be realized that the provision of a conical depression or concavity is not usually necessary as the foam will compress easily to adapt to the contour of the spider without unduly affecting the response of the loudspeaker, Foam material suitable to realize the inven-tion is commercially available from various manufacturers. Its basic requirements are flexibility, open cell structure and small pore size to provide maxilnum sound energy absorption in minimum weight and thickness~
The outer edge of the foam material is adhesively secured to the peripheral edge 14 of the loudspeaker 10. Of course, it is entirely possible to mechanically secure the foam material to the peripheral edge 14 such as by using a continuous clip along the edge 14. In any case, the joint between the foam material 15 and the spider 12 should preferably be air-impermeable.
The outer surface of the foam material 15 is covered by a flexible layer 16 of air-impermeable material which seals the pores of the foam material 15. Various rubber paints and compounds as well as some varnishes are ideally suited to the task. Of course, the sealing material and the foam rnaterial must be chemically compatible. For example, silicone rubber compounds have been found to be ideally sui-ted as sea'ling materia'ls.
The volume enclosed by the flexible layer 16 thus becomes the primary enclosure for loudspeaker 10. The efficiency of the enclosure may be increased by closing the circular opening at the center of the foam material 15. This may be achieved by adhesive'ly securing a circular piece of air-impermeable material 17 over the opening. Of course~ the piece 17 should be of a size adequate to seal the opening and may conveniently be made of ABS (Acrylonitrile-Butadine~Styrene) plastic. Alternately, the opening may be sealed simply with paper, cloth or plastic adhesive tape.
It should be realized, that a complete enclosure may also be created by using a thicker piece of foam material 15 such that a continuous skin or sealing layer may be obtained. However, the donut-shaped foam rnaterial lends itself to advantageous methods of manufacture as well as resulting in a more compact unit.
Figure 2 is a graphical representation of the improved performance of the transducer of the invention. Waveform 20 represents a nominal frequency response characteristics for a small unmodified loudspeaker mounted in a typical housing of a voice terminal. It is seen that the loudspeaker generates excessive acoustic output from about 200 to 650 hertz as well as a variety of other more minor variations across the voice frequency spectrurrl. These variations are due partly to the rescnant frPquency of the 'loudspeaker and partly to internal housing reflections due to the lack of a proper enc'losure for the loudspeaker. Waveform 21 illustrates the smoothing effect provided by the enclosure arrangement of the invention. The resonant frequency effects are cancelled and the ~61~ 17 efFects of housing reFlections are substantially minimized withou~ unduly affec-ting the low frequency response oF the speaker.
~aveform 22 illustrates the speaker response that might be expected if the primary enclosure was made of rigid material. The undesirable 400 hertz peak is eliminated, but at the expense of mutilating the low frequency response of the speaker.
The provision of a primary enclosure having d flexible outer layer ensures that there is energy coupling between the primary and secondary enclosures. Of course, the amount of coupling varies in accordance with the degree of flexibility of the sealing layer. The amount of coupling may be further increased by providing the sealing layer with one or more breather holes as indicated at 18. Increasing the size of the hole(s) or the flexibility of the sealing layer increases the low frequency response of the transducer~ Of course, the amount oF coupling required is dependent on the loudspeaker characteristics and may be determined with a rninimal amount of experimentation.
Figure 3 illustrates an enclosure arrangement in accordance with the invention. There is shown a typical voice communication terminal comprising a housing 30 which contains a variety of electronic components 31, a CRT 32 and an electro-acoustic transducer 33 having a construction as shown in figure 1. The attached flexible enclosure of transducer 33 provides a primary enclosure which is energy coupled to a secondary enclosure formed by the interior volume of housing 30.
It is seen therefore that the invention provides a loudspeaker having an improved frequency response characteristic. Because of its compact size and its flexible self-contained enclosure, the transducer may be fitted in a constrained location of a communication v~ L ~' terminal. The flexible enclosure may be deformed sliyhtly without causing the response of the loudspeaker to be greatly affected. Similarly, i-F it should be necessary due to space restrictions, it is entirely possible to shape the primary enclosure such as by cutting off a small portion. For example, the volume enclosed within the line A-A (fig. 1) and the outer surface 16 of the enclosure may simply be removed. Of course, the newly exposed surface of foam material 15 would then have to be re-sealed as with silicone rubber.
A loudspeaker consists of a voice coil or motor unit operating an acoustic conical diaphragm, one side of which acts on an enclosed space known as the loudspeaker enclosure. Since the enclosure provides an acoustical load on the diaphragm, the operating characteristics of a loudspeaker are influenced by the acous-tical properties of the enclosure. Throuyh the years, very substantial efforts have been directed towards the design of enclosures for the best possible reproduction of sound, especially for so-called high-fidelity equipment.
In the past few years, it has become increasingly common to provide telecommunication equipment and in particular, telephone equipment, with the capability for hands-free voice communication.
Similarly, combined voice/data advanced telecommunication terminals such as Displayphone (trademark of Northern Telecom) also use a loudspeaker to provide hands-free voice communication.
However, a number of problems are associated with this development. In the first place, the loudspeakers are usually mounted on an inside surface of the housing, often in a cramped location, and -the entire unit including a variety of electronic circuitry therefore becomes a haphazard enclosure for the loudspeaker. Secondly, since this type of equipment is meant to provide only voice communication as opposed to high-fidelity music and since manufac-turers find it desirable to minimize the cost and size of their equipment, the loudspeaker employed therein tends to be an inexpensive minia-ture unit having an acceptable frequency response only in the voice frequency ranye.
'7 Contributors to the marginal quality of sound produced by such loudspeaker arrangements reside in the lack of proper enclosure an(l in the effect of loudspeaker cone resonance which results in ti~e unit generating excessive acoustic output near the lower end of the voice frequency spectrum. Of course, the solution to this problem through the use of a custom designed enclosure is entirely feasible but prohibitively expensive.
There have been attempts in the past directed at the modification of a loudspeaker's output performance without mounting it in a proper enclosure. For example, United States patent No. 3,833,085 describes a low-frequency loudspeaker wherein the tendency to provide excessive midrange acoustic output was solved by providing ~he speaker with a circular disk of neoprene rubber mounted inside its conical diaphragm. The disk is attached adhesively at its periphery to the diaphragm at a circle spaced inwardly from the outer periphery of the diaphragm and at its center to the support dome for the loudspeaker.
Another method of modifying loudspeaker output response is described in United States patent No. 3,324,966 which discloses the combination of a loudspeaker and a pseudo-enclosure comprising a pair of sound absorbing chambers interconnected by a valving arrangement in the form of a narrow channel.
Yet another method of providing an enclosure for a loudspeaker is described in United States patent No. 3,720,285. The purpose of this device was to replace the absorbent material, such as glass fiber9 which is often used in enclosures. The patent provides an enclosure comprised of a rigid foamed plastic material which is moulded around a loudspeaker. On curing, the skin of the plastic seals the enclosure to provide a rigid self-contained enclosure, In addition to the practical manufacturing problems associated with such a device, the resultant enclosure increases the low resonant frequency of the loudspeaker. That is precisely the opposite of what the present invention achieves.
As effective as these prior art devices may be for their intended purpose, they represent inadequate, expensive and complex solutions to the problem at hand. I-t is thereFore an object of this invention to provide an economical and simple solution to the problem of shaping the frequency response of a miniature loudspeaker for use in voice communication terminalsO
In accordance with the invention, there is provided an electro-acoustic transducer for use in voice communication terminals adapted to receive voice frequency signals. A small loudspeaker has a voice coil structure and a conical diaphragm supported by a spider having a peripheral ed~e defining the shape of the loudspeaker. A piece of resilient open cell foam material having a shape complementary similar to that of the loudspeaker has one face provided with a concavity suitable for receiving the spider and the voice coil structure. The edge of the foam material is secured to the peripheral edge of the spider and the outer surface of the foam material is covered with a flexible layer of substantially air-impermeable material thereby providing the loudspeaker with an attached flexible back cavity enclosure.
It is also an object of the invention to provide loudspeakers used in voice communication terminals with an improved enclosure arrangement. This is achieved by providing the loudspeaker with a primary enclosure which comprises an attached flexible enclosure and a 7 ~
secondary enclosure which consists of -the terminal housing. The flexible enclosure is effective to smooth out the frequency response and to remove the low frequency peak due to the resonant frequency of the loudspeaker.
This is achieved without unduly affecting the normal low frequency response of the loudspeaker.
The invention therefore provides an economical enclosure arrangement for a piece of telecornmunication equipment wherein the response peak due to the resonant frequency of the loudspeaker is substantially eliminated and in which the overall frequency response is irnproved. Since the enclosure is small and flexible, the unit may be fitted in a cramped location of a piece of equipment. In addition, the loudspeaker will operate acceptably even if a portion of the flexible enclosure is deformed slightly against an adjacent component or if the enclosure is shaped to match its mounting space.
An example embodiment of the invention will now be described -in conjunction with the drawings in which:
Figure 1 is a partly sectional view of an electro-acoustic transducer in accordance with the invention;
Figure 2 is a graphical diagram illustrating a typical fre~uency response for the transducer of figure 1; and Figure 3 is a side view, partly in cross-section, of an enclosure arrangement in accordance with the invention.
Figure 1 shows a miniature loudspeaker 10 including a voice coil structure 11, and a spider 12 supporting a conical acoustic diaphragm 13. Such loudspeakers are available as commercial off-the-shelf iterns and may be circular or rectangular in shape. Common nominal sizes for these loudspeakers are about 21 inches in diameter or 21 inches by 3 inches. A
peripheral edge 14 oF the spider 12 defines the perimeter and shape of the loudspeaker 10.
Shown in cross-section is a piece of flexible foam material 15 having an open cell or air-permeable construction. The foam material has a shape complementary similar to that of the loudspeaker; that is, it is either circular or rectangular and is provided with an opening at its approximate geornetrical center as well as a conical depression to allow close-fitting engagement with the voice coil structure 11 and the spider 12. For a circular loudspeaker, the foam material is thus somewhat donut-shaped. Of course, it should be realized that the provision of a conical depression or concavity is not usually necessary as the foam will compress easily to adapt to the contour of the spider without unduly affecting the response of the loudspeaker, Foam material suitable to realize the inven-tion is commercially available from various manufacturers. Its basic requirements are flexibility, open cell structure and small pore size to provide maxilnum sound energy absorption in minimum weight and thickness~
The outer edge of the foam material is adhesively secured to the peripheral edge 14 of the loudspeaker 10. Of course, it is entirely possible to mechanically secure the foam material to the peripheral edge 14 such as by using a continuous clip along the edge 14. In any case, the joint between the foam material 15 and the spider 12 should preferably be air-impermeable.
The outer surface of the foam material 15 is covered by a flexible layer 16 of air-impermeable material which seals the pores of the foam material 15. Various rubber paints and compounds as well as some varnishes are ideally suited to the task. Of course, the sealing material and the foam rnaterial must be chemically compatible. For example, silicone rubber compounds have been found to be ideally sui-ted as sea'ling materia'ls.
The volume enclosed by the flexible layer 16 thus becomes the primary enclosure for loudspeaker 10. The efficiency of the enclosure may be increased by closing the circular opening at the center of the foam material 15. This may be achieved by adhesive'ly securing a circular piece of air-impermeable material 17 over the opening. Of course~ the piece 17 should be of a size adequate to seal the opening and may conveniently be made of ABS (Acrylonitrile-Butadine~Styrene) plastic. Alternately, the opening may be sealed simply with paper, cloth or plastic adhesive tape.
It should be realized, that a complete enclosure may also be created by using a thicker piece of foam material 15 such that a continuous skin or sealing layer may be obtained. However, the donut-shaped foam rnaterial lends itself to advantageous methods of manufacture as well as resulting in a more compact unit.
Figure 2 is a graphical representation of the improved performance of the transducer of the invention. Waveform 20 represents a nominal frequency response characteristics for a small unmodified loudspeaker mounted in a typical housing of a voice terminal. It is seen that the loudspeaker generates excessive acoustic output from about 200 to 650 hertz as well as a variety of other more minor variations across the voice frequency spectrurrl. These variations are due partly to the rescnant frPquency of the 'loudspeaker and partly to internal housing reflections due to the lack of a proper enc'losure for the loudspeaker. Waveform 21 illustrates the smoothing effect provided by the enclosure arrangement of the invention. The resonant frequency effects are cancelled and the ~61~ 17 efFects of housing reFlections are substantially minimized withou~ unduly affec-ting the low frequency response oF the speaker.
~aveform 22 illustrates the speaker response that might be expected if the primary enclosure was made of rigid material. The undesirable 400 hertz peak is eliminated, but at the expense of mutilating the low frequency response of the speaker.
The provision of a primary enclosure having d flexible outer layer ensures that there is energy coupling between the primary and secondary enclosures. Of course, the amount of coupling varies in accordance with the degree of flexibility of the sealing layer. The amount of coupling may be further increased by providing the sealing layer with one or more breather holes as indicated at 18. Increasing the size of the hole(s) or the flexibility of the sealing layer increases the low frequency response of the transducer~ Of course, the amount oF coupling required is dependent on the loudspeaker characteristics and may be determined with a rninimal amount of experimentation.
Figure 3 illustrates an enclosure arrangement in accordance with the invention. There is shown a typical voice communication terminal comprising a housing 30 which contains a variety of electronic components 31, a CRT 32 and an electro-acoustic transducer 33 having a construction as shown in figure 1. The attached flexible enclosure of transducer 33 provides a primary enclosure which is energy coupled to a secondary enclosure formed by the interior volume of housing 30.
It is seen therefore that the invention provides a loudspeaker having an improved frequency response characteristic. Because of its compact size and its flexible self-contained enclosure, the transducer may be fitted in a constrained location of a communication v~ L ~' terminal. The flexible enclosure may be deformed sliyhtly without causing the response of the loudspeaker to be greatly affected. Similarly, i-F it should be necessary due to space restrictions, it is entirely possible to shape the primary enclosure such as by cutting off a small portion. For example, the volume enclosed within the line A-A (fig. 1) and the outer surface 16 of the enclosure may simply be removed. Of course, the newly exposed surface of foam material 15 would then have to be re-sealed as with silicone rubber.
Claims (18)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An electro-acoustic transducer comprising, a small loudspeaker having a voice coil structure and a conical diaphragm supported by a spider having a peripheral edge defining the shape of the loudspeaker, a piece of resilient open cell foam material having a shape complementary similar to that of the loudspeaker and including an opening at its approximate geometrical center to permit close-fitting engagement with said voice coil structure and means for securing the peripheral edge of one face of said foam material to said peripheral edge of the spider, the outer surface of the foam material being covered with a flexible layer of substantially air-impermeable material, thereby providing the loudspeaker with an attached flexible enclosure.
2. The electro-acoustic transducer defined in claim 1 and further comprising a piece of air-impermeable material of a size at least marginally larger than said opening, the material being adhesively secured to said foam material to effectively seal said opening.
3. The electro-acoustic transducer defined in claim 2 wherein the material is a thin disk of ABS plastic.
4. The electro-acoustic transducer defined in claim 2 wherein the outer flexible layer of the enclosure is provided with at least one energy coupling hole.
5. The electro-acoustic transducer defined in claim 1 wherein said one face of the foam material is also provided with a conical concavity suitable for accommodating said spider.
6. The electro-acoustic transducer defined in claim 1 wherein said foam material is adhesively secured to said peripheral edge.
7. An electro-acoustic transducer comprising, a small loudspeaker having a voice coil structure and a conical diaphragm supported by a spider having a peripheral edge defining the shape of the loudspeaker, a piece of resilient open cell foam material having a shape complementary similar to that of the loudspeaker, one face of the foam material having a concavity suitable for receiving said spider and said voice coil structure, and means for securing the peripheral edge of said one face of the foam material to said peripheral edge, the outer surface of the foam material being covered with a flexible layer of substantially air-impermeable material whereby the loudspeaker is provided with an attached flexible enclosure.
8. The electro-acoustic transducer defined in claim 7 wherein the outer flexible layer of the enclosure is provided with at least one energy coupling hole.
9. The electro-acoustic transducer defined in claim 7 wherein said foam material is adhesively secured to said peripheral edge.
10. An enclosure arrangement for a loudspeaker adapted to be mounted in the housing of a voice communication terminal, comprising, a primary enclosure comprising a small flexible enclosure attached to the loudspeaker, and a secondary enclosure comprising the housing in which the loudspeaker and its attached primary enclosure are mounted, the flexibility of the primary enclosure allowing interaction between itself and the secondary enclosure.
11. An enclosure arrangement for a loudspeaker adapted to be mounted in the housing of a voice communication terminal, the loudspeaker including a voice coil structure and a spider supporting a diaphragm, the arrangement comprising: a primary enclosure comprising a piece of resilient open cell foam material having an opening at its approximate geometrical center to permit close-fitting engagement with said voice coil structure, the peripheral edge of one face of the foam material being secured to the peripheral edge of the spider and the outer surface of the foam material having a flexible layer of substantially air-impermeable material whereby the loudspeaker is provided with an attached flexible enclosure, the secondary enclosure comprising the housing in which the loudspeaker and the attached primary enclosure are mounted, the flexibility of the primary enclosure allowing interaction between itself and the secondary enclosure.
12. The enclosure arrangement defined in claim 11 wherein the opening in the flexible primary enclosure is sealed with a piece of air-impermeable material adhesively secured to the foam material.
13. The enclosure arrangement defined in claim 12 wherein the flexible layer of the primary enclosure is provided with at least one energy coupling hole.
14. The enclosure arrangement defined in claim 11 wherein the foam material of the primary enclosure is adhesively secured to said peripheral edge.
15. The enclosure arrangement defined in claim 11 wherein said one face of the foam material is also provided with a conical concavity suitable for accommodating said spider.
16. An enclosure arrangement for a loudspeaker adapted to be mounted in the housing of a voice communication terminal, the loudspeaker including a voice coil structure and a spider supporting a diaphragm, the arrangement comprising: a primary enclosure comprising a piece of resilient open cell foam material having one face provided with a concavity suitable for receiving the spider and the voice coil structure of the loudspeaker, the peripheral edge of said one face of the foam material being secured to the peripheral edge of the spider and the outer surface of the foam material having a flexible layer of substantially air-impermeable material whereby the loudspeaker is provided with an attached flexible enclosure, the secondary enclosure comprising the housing in which the loudspeaker and the attached primary enclosure are mounted, the flexibility of the primary enclosure allowing interaction between itself and the secondary enclosure.
17. The enclosure arrangement defined in claim 16 wherein the outer flexible layer of the primary enclosure is provided with at least one energy coupling hole.
18. The enclosure arrangement defined in claim 16 wherein the foam material of the primary enclosure is adhesively secured to the peripheral edge of the spider.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000430527A CA1196717A (en) | 1983-06-16 | 1983-06-16 | Loudspeaker enclosure arrangement for voice communication terminals |
| AT84303212T ATE36794T1 (en) | 1983-06-16 | 1984-05-11 | LOUDSPEAKER HOUSING FOR VOICE TRANSMISSION STATIONS. |
| DE8484303212T DE3473718D1 (en) | 1983-06-16 | 1984-05-11 | Loudspeaker enclosure arrangement for voice communication terminals |
| EP84303212A EP0129320B1 (en) | 1983-06-16 | 1984-05-11 | Loudspeaker enclosure arrangement for voice communication terminals |
| JP59123539A JPS6014596A (en) | 1983-06-16 | 1984-06-15 | Speaker enclosure unit for voice communication terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000430527A CA1196717A (en) | 1983-06-16 | 1983-06-16 | Loudspeaker enclosure arrangement for voice communication terminals |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1196717A true CA1196717A (en) | 1985-11-12 |
Family
ID=4125491
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000430527A Expired CA1196717A (en) | 1983-06-16 | 1983-06-16 | Loudspeaker enclosure arrangement for voice communication terminals |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0129320B1 (en) |
| JP (1) | JPS6014596A (en) |
| AT (1) | ATE36794T1 (en) |
| CA (1) | CA1196717A (en) |
| DE (1) | DE3473718D1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NZ225001A (en) * | 1987-06-16 | 1990-09-26 | Matsushita Electric Ind Co Ltd | Loudspeaker: reflected sound waves absorbed |
| US8767994B2 (en) | 2010-11-19 | 2014-07-01 | Apple Inc. | Gas filled speaker volume |
| US8837768B2 (en) | 2011-03-28 | 2014-09-16 | Bose Corporation | Electro-acoustic transducer enclosure |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE673136A (en) * | ||||
| GB790998A (en) * | 1953-10-23 | 1958-02-19 | Tesla Np | A device for the reproduction of sound |
| FR1152433A (en) * | 1956-06-20 | 1958-02-17 | Speaker training | |
| US4090582A (en) * | 1976-11-02 | 1978-05-23 | Deschu Dennis F | Speaker protector |
| JPS5616876U (en) * | 1979-07-16 | 1981-02-14 | ||
| FR2470511A1 (en) * | 1979-11-20 | 1981-05-29 | Faugeras Alain | Active-passive loudspeaker chamber - has passive speaker facing chamber base to provide Helmholtz resonator |
| DE2948034A1 (en) * | 1979-11-29 | 1981-06-11 | Telefonbau Und Normalzeit Gmbh, 6000 Frankfurt | Electroacoustic converter assembly - has loudspeaker mounted inside housing divided into two chambers by PCB |
-
1983
- 1983-06-16 CA CA000430527A patent/CA1196717A/en not_active Expired
-
1984
- 1984-05-11 AT AT84303212T patent/ATE36794T1/en active
- 1984-05-11 EP EP84303212A patent/EP0129320B1/en not_active Expired
- 1984-05-11 DE DE8484303212T patent/DE3473718D1/en not_active Expired
- 1984-06-15 JP JP59123539A patent/JPS6014596A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0129320A1 (en) | 1984-12-27 |
| EP0129320B1 (en) | 1988-08-24 |
| ATE36794T1 (en) | 1988-09-15 |
| JPS6014596A (en) | 1985-01-25 |
| DE3473718D1 (en) | 1988-09-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |