AU609395B2 - Electroacoustic transducer device - Google Patents
Electroacoustic transducer device Download PDFInfo
- Publication number
- AU609395B2 AU609395B2 AU73345/87A AU7334587A AU609395B2 AU 609395 B2 AU609395 B2 AU 609395B2 AU 73345/87 A AU73345/87 A AU 73345/87A AU 7334587 A AU7334587 A AU 7334587A AU 609395 B2 AU609395 B2 AU 609395B2
- Authority
- AU
- Australia
- Prior art keywords
- transducer device
- electroacoustic transducer
- cavity
- transducer
- electroacoustic
- 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.)
- Ceased
Links
- 238000006073 displacement reaction Methods 0.000 claims description 15
- 230000004044 response Effects 0.000 claims description 13
- 230000008878 coupling Effects 0.000 claims description 7
- 238000010168 coupling process Methods 0.000 claims description 7
- 238000005859 coupling reaction Methods 0.000 claims description 7
- 229920000742 Cotton Polymers 0.000 claims description 4
- 238000013016 damping Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 claims description 2
- 230000000881 depressing effect Effects 0.000 claims 1
- 230000035945 sensitivity Effects 0.000 description 3
- 230000001413 cellular effect Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000000994 depressogenic effect Effects 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 239000006261 foam material Substances 0.000 description 2
- XCWPUUGSGHNIDZ-UHFFFAOYSA-N Oxypertine Chemical compound C1=2C=C(OC)C(OC)=CC=2NC(C)=C1CCN(CC1)CCN1C1=CC=CC=C1 XCWPUUGSGHNIDZ-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/02—Constructional features of telephone sets
- H04M1/03—Constructional features of telephone transmitters or receivers, e.g. telephone hand-sets
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/02—Constructional features of telephone sets
- H04M1/21—Combinations with auxiliary equipment, e.g. with clocks or memoranda pads
- H04M1/215—Combinations with auxiliary equipment, e.g. with clocks or memoranda pads by non-intrusive coupling means, e.g. acoustic couplers
- H04M1/2155—Acoustic coupling
-
- 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
- H04R1/225—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only for telephonic receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/06—Loudspeakers
- H04R9/063—Loudspeakers using a plurality of acoustic drivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
- H04R9/10—Telephone receivers
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
Description
U6VLYSTE;6L ZAXMAnsbdouwjpj!Hrj~ppD 1.25 1.4Z.AXMAnsNOdoNW1)NrHeodaD2V 'id' 01
[III!-
1.8 1_.25
I
0 6 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION (Original) 609395 FOR OFFICE USE Class Int. Class Application Number: Lodged: Complete <,pecific~tion Lodged: Accepted: Published: -,priority: a 'Related Art: This document c t foriT amendmients macic under Section 49 aind is correct for prn ng 00 0 o 000 Name of Applicant: INTERACT TECHNOLOGY P./L.
69 Sutherland Road, Armadale, Victoria 3143,
AUSTRALIA.
Address of Applicant: a ctual Inventor(s): 4 Address for Service: BREEN Done lly James DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.
Complete specification for the invention entitled: "EILECTROACOUSTIC TRANSDUCER DEVICFlk The following statement is a full description of this invention, including the best method of performing it known to us 1- To: THE COMMISSIONER OF PATENTS (a member of the firm of DAVIES COLLISON for and on behalf of the Applicant).
Davies Collison, Melbourne and Canberra.
i F, rii -*ir i- r d r r
I
I
ELECTROACOUSTIC TRANSDUCER DEVICE This invention relates to an electroacoustic transducer device.
Two principal types of moving coil electroacoustic transducers, usable as loud speakers or microphones, are known. The first is a volume displacement transducer, generally used to create 00 o00 0 a sound levels in a room or interactively loaded oi 10 chamber. Usually, the intention is to provide a linear sound output in the sense that the sound output for a constant input signal is constant over wide 00 o oc frequency range. These transducers are usually o0 a characterized in that the "core", which is moved to 15 create the sound is loosely suspended, the cone itself 0 0 r o o o being a compliant or non-rigid type. A relatively small magnet is used to provide the magnetic flux which interacts with current flowing in the coil of °o 'S the transducer to effect movement of the cone.
o a °0 .o 20 On the other hand, another type of moving coil transducer is used to create linear sound pressure in a small sealed or semi-sealed chamber. Such a transducer i- known as a pressure generating transducer. These transducers are used in applications such as in _i *tj-k app~I II~~L~:li- t m. maic i. -Cznention eountfy in r:spee! ef th: in%, vt4en4t"Z+B t of Insert place and date of signature.
Signature of Declarant(s) f'attestation required).
Note: Initial all alterations.
Declared at ARMADALE this TWENTY-II NTH dayo?) MAY 19 DAVIES COLLISON. MELBOURNEid CANBE RA.
86 telephone handsets (the closed cavity being formed when the ear-piece is bought against the users ear) and in acoustic couplers such as of the type which are fitted over the mouth-piece of a telephone handset and activated to provide coded sound output to the handset for data transfer through the hand-set. These transducers are generally characterized by having stiff cone suspension, a rigid cone and a very large and powerful magnet.
Whereas the relatively small magnets employed with volume displacement transducers generally provide Screlatively low electrical sensitivity, the larger magnets employed in pressure generating transduc rs result in higher electrical sensitivity.
In general, the two different types of transducer t' described above have been used in quite different applications, and it has been impracticable to employ volume displacement transducers in applications where customarily, pressure generating transducers are 20 employed. On the other hand, advantageous results would arise if simple means existed for adapting a volume displacement transducer for use in the applications for which pressure generating transducers are customarily employed. In particular, the volume displacement transducers are considerably cheaper, smaller and lighter in weight.
SThe reason why volume displacement transducers are not used for applications where pressure generating transducers are employed is that these devices are incapable of generating a constant sound pressure level when positioned in a sealed cavity.
w~f These transducers will, in these applications, normally exhibit a falling response as the inpuc frequency rises; that is to say the higher the input frequency, the less sound pressure is generated in the cavity.
An object of the invention is to provide an electroacoustic transducer device arranged whereby to permit a volume displacement transducer to be employed in an arrangement where the transducer acts in a small chamber.
According to the invention there is provided an i electroacoustic transducer device comprising: .0 an electroacoustic transducer adapted to C generate and direct sound outwardly therefrom in response to an electrical signal, and means defining first and second cavities when said transducer device is positioned against a surface of a receiver device, said first cavity being adapted to provide acoustic coupling with said receiver device and said second cavity being acoustically coupled, in use, with said first cavity.
The invention is further described, by way of ;example only, with reference to the accompanying drawings wherein: t jr I I I Figure 1 is a cross sectional side view of a device constructed in accordance with the invention; and Figure 2 is a cross sectional view A-A of the device shown in Figure 1.
An electroacoustic transducer device 10, as shown in Figure 1, is in the form of an ustic coupler being a device fittable over the mouth-piece 12 of a telephone. A closed cavity 14 is formed when the device 10 is fitted on the mouth piece 12 whereby the device is effective to transmit coded acoustic signals 0 to the telephone mouth-piece 12 so as to transmit data through a telephone line associated with the telephone.
15 The device 10 comprises a cup shaped housing C V to which is attached, by means of screws 22, a circuit board 24 and a cylindrical lid 26. Permanently attached to the bottom of the housing 20 is an annular rubber sealing member 28 which when placed over the inouth-piece 12 bounds the cavity 14, together with the r mouth-piece 12 and the housing A volume displacement transducer 30, the components 32 of an integrated circuit and a key-pad 34 are attached to the circuit board 24. The volume displacement transducer 30 comprises a small cylindrical magnet 40 which provides a central annular recess 41 into which a coil 42 may be placed. The coil 42 is attached to a diaphragm or cone 44. The volume displacement transducer 30 generates tones in accordance with depressed keys of the key-pad 34.
When a key or pair of keys are depressed the A 6 integrated circuit provided in the device 10 generates a certain current which is applied to the coil 42.
The magnetic flux generated by the current within coil 42 interacts with that of the magnet 40 and hence the coil moves so as to vibrate the diaphragm 44 in such a fashion that sound waves representative of selected tones are generated. The sound waves are generated in a generation cavity 60 bounded by the diaphragm 44, the bottom surface of the housing 20 and the walls of a cylinder 62 made of acoustic insulative material. A rectangular block 70 is provided for preventing the Vc diaphragm 44 from turning inside out. Preferably, CCC however, the generation cavity 60 is configured so tet that the bottom surface of the housing 20 prevents the 4* 15 diaphragm 44 from turning inside out and the block o00 is not required.
0 0 I o The housing 20 is provided with a plurality of perforations or holes 64 which are distributed in a uniform arrangement about a circular surface 66 (shown S°o 20 in figure which is concentric with the cylindrical 0o°\a wall 68 of the housing 20. The generation cavity is acoustically coupled to the meuth-piece cavity 14 0s* 9by means of a predetermined number of the holes 64, In the preferred embodiment, the transducer 30 is offset from the central axis 80 of the device so that o°j the generation cavity 60 communicates with only approximately 30% of the holes 64. Hence, the tones geinerated by the transducer 30 are acoustically ioupled to the receiver of the mouth piece 12 by means of a first cavity comprising the generation cavity and the mouth piece cavity 14.
The construction of the device 10 is such that a second cavity is provided, in communication with the first cavity, in order to ensure the sound pressure i-ii Y ~f 7 level generated by the device 10 is substantially constant for generated tones within the frequency range 700-2100Hz. The second cavity comprises: a main cavity 90, bounded by the top surface of the housing 20, the wall 68 of the housing 20, the bottom surface of the circuit board 24 and the outside wall of the volume displacement transducer 30; and a rear cavity 92, bounded by the top surface 82 of the diaphragm 44, a supporting structure 31 of the transducer 30, and a cylinder 84 made from ruptured cellular foam material, which is acoustically passive, and positioned at the top of the supporting structure 31. The main cavity 90 is coupled or communicates with the mouth-piece cavity 14, in the preferred embodiment, by means of approximately 70% of the holes I t64.
AS volume displacement transducers have a characteristic falling sound pressure level response as frequency increases, in order to produce a C 20 substantially constant response over the frequency C range 700-2100 Hz the device 10 is designed to suppress the characteristic response for low frequencies and boost the response for high frequencies.
The size of the first and second cavities and their respective acoustic coupling are designed so as to introduce resonance in the frequency response at approximately 1400-1500 Hz. The resonance peak introduced by the acoustic coupling between the two cavities is damped to a desired level by placing a thin material of cotton 100 over the surface 66 and, 8 accordingly, the holes 64. The cotton 100 provides acoustic damping of the resonance peak and spreads the base of the peak the Q of the resonance peak is effectively decreased).
In order to suppress the low frequency response of the device 10 the cavity 92 behind the diaphragm 44 is provided to restrict the sensitivity of the volume displacement transducer 30. The cylinder 84 made of ruptured cellular foam material ant the rear cavity 92 provide an air pocket behind the diaphragm 44 which restricts the movemen,t of the diaphragm 44 over the low frequency range.
o c4 The sizes of the cavities, their respective aa acoustic coupling and the acoustic damping provided by o000 15 the cotton 100 are all critically selected so as to 0 o provide the resulting sound pressure level response oo Oo S0 which is substantially constant over the frequency Srange 700-2100 Hz. Preferably the sound pressure level does not vary by more than ±2 dB over this 20 frequency range. Without the above-mentioned 00 o ooo compensating features the volume displacement o 0o transducer 30 would have a falling response of up to 10 dB over the range 700 2100Hz.
0 00 So The transducer 30 is also displaced from the center axis 80 of the device 10 so that an area remains which may be employed as an air path for voice o0 0 0o 0 transmission to a user.
00o 0 The described construction has been advanced merely by way of explanation and many modifications may be made thereto without departing from the spirit and scope of the invention which includes every novel feature and combination of novel features herein disclosed.
I
Claims (18)
1. An electroacoustic transducer device comprising: an electroacoustic transducer adapted to generate and direct sound outwardly therefrom in response to an electrical signal, and means defining first and second cavities when said transducer device is positioned against a surface of a receiver device, said first cavity being adapted to provide acoustic coupling with said receiver device and said second cavity being acoustically coupled, in use, with said first cavity.
2. An electroacoustic transducer device as I claimed in claim 1, wherein said first and second e 'cavities are acoustically coupled, in use, by a first predetermined number of holes provided in the base of said transducer device.
3. An electroacoustic transducer device as claimed in claim 1 or 2, further comprising a housing and a sealing member attached to the bottom of the housing and which enables said transducer device to engage the receiver device and define said first cavity.
4. An electroacoustic transducer device as claimed in claim 3, wherein said first cavity comprises a closed cavity, bounded by said receiver device, the sealing member and the bottom of the housing, and a generation cavity in which sound is generated, bounded by the front surface of a diaphragm of the transducer, acoustically insulative M J material and the bottom of the housing, said closed cavity and said generation cavity being acoustically coupled by a second predetermined number of holes in the bottom of said housing.
An electroacoustic transducer device as claimed inany .no e-of the preeding claims, wherein said second cavity includes a rear. cavity which is adjacent the rear of the diaphragm of the transducer.
6. An electroacoustic transducer device as claimed in any one of the preceding claims, further jC comprising a key-pad and an electric circuit configured on a printed circuit board, wherein i i depressing a key or keys of said key-pad causes said Scircuit to generate said electric signal, which Scorresponds to a predetermined tone to be generated. 44
7. An electroacoustic transducer device as claimed \n claim 2, wherein said holes are uniformly S r istributed about the central axis of the transducer device and said first predetermined number is 70% of the total number of said holes.
8. An electroacoustic transducer device as claimed in claim 4, wherein said holes are uniformely distributed about the central axis of the transducer device and said second predetermined number is 30% of the total number of said holes.
9. An electroacoustic transducer device as claimed in anyone of the preceding claims, being such that the sound pressure level generated by the transducer device is substantially constant over a 11 predetermined frequency range.
An electroacoustic transducer device as claimed in claim 9, wherein the size of and the acoustic coupling between the first and second cavities are such that resonance is introduced at high frequencies in said predetermined range so as to increase the frequency response of said transducer at said high frequencies.
11. An electroacoustic transducer device as claimed in claim 10, further comprising acoustic oS s* damping means to dampening said acoustic coupling so O as to reduce said resonance to a desired level. o p 0 0 og o"
12. An electroacoustic transducer device as Sclaimed in claim 11, wherein said acoustic damping 0 Ono means comprises a thin layer of cotton placed between said first ond second cavities. o
13. An electroacoustic transducer as claimed in 0 0 any one of claims 10 to 12, wherein said resonance 0 a occurs at approximately 1400 1500 Hz.
14. An electroacoustic transducer device as 0 n claimed in any one of claims 9 to 13, wherein said O second cavity restricts the movement of the diaphragm o o of the transducer so as to suppress the frequency response of said transducer at low frequencies in said predetermined range.
An electroacoustic transducer device as claimed in any one of claims 9 to 14, wherein said predetermined range is 700 2100 Hz. iCII1 12
16. An electroacoustic device as claimed in anyone of to proc claim- wherein the jound pressure level generated over said predetermined range does not vary by more than ±2 dB.
17. An electroacoustic transducer device as claimed in anyone of the preceding claims, wherein said transducer is a volume displacement transducer.
18. An electroacoustic transducer device substantially as hereinbefore described with reference to the accompanying drawings. DATED this 22nd day of May, 1987. c 1 t INTERACT TECHNOLOGY P./L. S t l By its Patent Attorneys DAVIES COLLISON i C F
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU73345/87A AU609395B2 (en) | 1986-05-22 | 1987-05-22 | Electroacoustic transducer device |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPH604486 | 1986-05-22 | ||
| AUPH6044 | 1986-05-22 | ||
| AU73345/87A AU609395B2 (en) | 1986-05-22 | 1987-05-22 | Electroacoustic transducer device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU7334587A AU7334587A (en) | 1987-11-26 |
| AU609395B2 true AU609395B2 (en) | 1991-05-02 |
Family
ID=25637304
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU73345/87A Ceased AU609395B2 (en) | 1986-05-22 | 1987-05-22 | Electroacoustic transducer device |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU609395B2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3299207A (en) * | 1963-08-29 | 1967-01-17 | Cooke Robert James | Sound reproducer with means for attachment to a telephone handpiece |
| US3360071A (en) * | 1965-08-02 | 1967-12-26 | Chromalloy Corp | Acoustical coupler |
| US3553374A (en) * | 1969-03-20 | 1971-01-05 | Digitronics Corp | Acoustic coupler |
-
1987
- 1987-05-22 AU AU73345/87A patent/AU609395B2/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3299207A (en) * | 1963-08-29 | 1967-01-17 | Cooke Robert James | Sound reproducer with means for attachment to a telephone handpiece |
| US3360071A (en) * | 1965-08-02 | 1967-12-26 | Chromalloy Corp | Acoustical coupler |
| US3553374A (en) * | 1969-03-20 | 1971-01-05 | Digitronics Corp | Acoustic coupler |
Also Published As
| Publication number | Publication date |
|---|---|
| AU7334587A (en) | 1987-11-26 |
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