Patent Application
20140153737
The present invention relates generally to a receiver assembly including multiple receivers assembled jointly for playback of audio in headphones, hearing aid instruments and head sets.
For playback of audio in headphones and hearing aids receivers are applied that convert an electric signal representing an audio stream into sound. A common type of receiver is the balanced armature type: an electro-acoustic transducer which converts energy from electrical energy to acoustical energy. Balanced armatures have limitations regarding the reproduction of sound due to e.g. nonlinearity of the flux field, saturation of the armature and mechanical compliance. The overall frequency response and bandwidth are affected by the design, dimension and construction of the balanced armature receiver. In particular, the balanced armature has typical resonant frequencies that influence frequency response. To address these limitations it is known to apply multiple receivers that are each designed to reproduce a specific portion of the sound frequency spectrum, such as e.g. tweeter, mid-range or woofer transducer assemblies reproducing high, mid and low frequency ranges respectively. As these frequency spectra may partially overlap, the joint frequency response of the receivers will be deficient likewise. To address this problem it is known to apply acoustic filters acoustically downstream. These are placed outside the spout of the receiver, but necessitate a complicated construction of the earphone itself to bring the sound of two receivers together into one acoustic channel to deliver the sound to the ear of a user. This means additional volumes affecting mainly the reproduction of higher frequencies. Moreover, installing such a receiver assembly in e.g. an ear phone product is more difficult and thus time consuming; which in turn increase costs of manufacture. In order to reduce the amount of space taken up by a multiple receiver assembly, dual receiver assemblies have been developed wherein two transducer assemblies are combined in a single housing with a single spout; usually a combination of a woofer and a tweeter or a woofer and a mid-range receiver. To further reduce the amount of space taken up by a dual receiver assembly, in U.S. 2009/0060245 it is disclosed to apply a constriction plate with a generally circular shaped aperture located inside the spout, instead of a complex construction outside of the spout. The aperture functions as an acoustic low pas filter and is applied to the sound outlet port of a woofer transducer assembly. However, the filter response of the circular aperture in the constriction plate is strongly non-linear resulting in undesirably high time harmonic distortions.
It is an object of the present invention to provide a receiver assembly that overcomes the drawbacks mentioned above.
In a FIRST aspect, the present invention relates to a receiver assembly comprising a first receiver housing comprising a first sound outlet port; a second receiver housing comprising a second sound outlet port and a spout, and wherein the second receiver housing is positioned over the first sound outlet port. The receiver assembly further comprising an acoustic duct located between the first and second receiver housing acoustically connecting the first sound outlet port to the spout; and an acoustic mass positioned in an end portion of the acoustic duct close to the spout. Applying an acoustic mass in the acoustic duct of a receiver assembly according to the first aspect of the invention has the effect of the output of the first receiver as being passed through a low pass filter. Moreover, as for a common dual receiver the dimensions of the housing for each transducer are the same the overall frequency response is compromised: the dimensions are only optimal for one of the transducer assemblies or even sub-optimal for both transducer assemblies. The merging of the respective frequency response of each receiver is achieved according to the first aspect of the invention without compromising the overall response by the chosen design, as the first and second housing can be dimensioned to their respective frequency ranges: woofer and mid-range or tweeter.
In a further embodiment, the acoustic duct comprises a chamber and a passage, wherein the passage runs from the chamber towards the spout. The chamber allows proper acoustic connection between the acoustic duct and the first sound outlet of the first receiver, while the passage allows ease of accurately positioning and fitting the acoustic mass in the end portion of the acoustic duct.
In a preferred embodiment, the acoustic duct is provided as a spacer member. This assures a predetermined distance between the first and second receiver to accommodate the acoustic mass. In a further embodiment, the spacer member comprises a plate with a cut-out portion, the cut-out portion constituting the chamber, passage and a recess. When fixating the acoustic mass in the passage of the acoustic duct with glue, a recess at the end of the passage on the edge of the plate prevents the glue from entering the acoustic mass. Furthermore, the spacer member can be shaped such that the plate extends beyond the dimension of the receivers allowing it to function as bracket member facilitating ease of installing the receiver assembly in e.g. an earphone or headset.
In one embodiment, the outlet port of the second receiver is acoustically connected directly to the spout. In this manner, the acoustic output of both receivers is merged in a single spout. In another embodiment, the outlet port of the second receiver is connected to the acoustic duct. This provides the possibility to have a dual woofer assembly of which the joint acoustic output is passed through a low pass filter. Hence, both first and second receiver are provided with a woofer motor assembly giving an improved acoustic performance in the low frequency range. Such a dual woofer assembly can be advantageously in a three driver two way setup or a four driver three way setup; receiver assemblies with respectably three or four acoustic drivers wherein two drivers are arranged to produce a same frequency response.
In a SECOND aspect, the present invention relates to a method for assembling a receiver assembly comprising: providing a first receiver housing comprising a first sound outlet port, a second receiver housing comprising a second sound outlet port and providing an acoustic duct, positioning the second receiver housing over the sound outlet port of the first receiver housing, and positioning the acoustic duct between the first and second receiver housing such that it is located over the first sound outlet port of the first receiver and acoustically connected with the first sound outlet port and that an end portion of the acoustic duct is located near the second sound outlet port. The method further comprises positioning of an acoustic mass in the end portion of the acoustic duct and placing a spout over the second sound outlet port and the end portion of the acoustic duct. Mounting the second receiver over the sound outlet port of the first receiver facilitates locating the acoustic duct between the first and second receiver such that the acoustic duct runs from the first sound outlet port towards the spout. The thus provided acoustic connection between the first sound outlet port and the spout facilitates positioning an acoustic mass. A consequently therein located acoustic mass provides an acoustic low pass filter function.
In a preferred embodiment the method further comprise s providing the acoustic duct as a spacer member, and prior to positioning the acoustic duct between the first and second receiver housing, mounting the acoustic duct to the second receiver housing such that the end portion of the acoustic duct is located near the second sound outlet port of the second receiver housing. By providing the acoustic duct as a spacer member allows two receivers to be assembled in a simple manner; first mounting the acoustic duct c.q. spacer member to the second receiver facilitates ease of aligning the acoustic duct with the first sound outlet port of the first receiver.
According to a further embodiment, the method comprises applying glue to fixate the acoustic mass. This allows sealing off any clefts or openings between an outer diameter of the acoustic mass and an inner diameter of the acoustic duct.
In general, in a receiver assembly as described above the receivers are spaced apart to accommodate the acoustic duct and results in a more complex structure in comparison with a common dual receiver. However, applying the acoustic mass facilitated by the acoustic duct provides a universal, accurate, flexible, and more linear method to determine acoustic impedance and in particular a low pass crossover point. This allows improved control for determining and even flattening of the frequency characteristic of the receiver assembly.
In the context of the present invention the term ‘receiver housing’ shall designate any housing apt for a transducer assembly comprising a motor assembly driving a diaphragm and capable of producing sound in response to activation of the transducer assembly.
The invention will now be described in further detail with reference to the accompanying drawings, wherein:
An example of an embodiment of a receiver assembly 1 according to the invention is shown in
The according to the above obtained assembly 1 comprises first receiver housing 2 comprising a first sound outlet port 3, second receiver housing 4 comprising second sound outlet port 5 and a spout 6. In the assembly the second receiver housing 4 is positioned over the first sound outlet port 3, while the spout 6 is positioned over the second outlet port 5. Furthermore, the acoustic duct 7 is located between the first receiver housing 2 and the second receiver housing 4 and acoustically connects the first sound outlet port 3 to the spout 6. The acoustic mass 8 is positioned in the end portion of the acoustic duct 7 close to the spout 6. In this embodiment, the acoustic mass 8 comprises a tube in cross-section having an inner contour of circular shape. However, other cross-sectional shapes as square or hexagonal shapes are also possible. The outer diameter of the tube corresponds to the inner diameter of the end portion of the acoustic duct 7. The choice for the dimensions of the tube, length and inner diameter, depends on the desired corner frequency. Especially the inner diameter is set for tuning the corner frequency, e.g. an inner diameter of 0.1 mm results in a corner frequency 100 Hz (subwoofer), while 0.2 mm results in a corner frequency 1 kHz. The inner diameter is usually selected from 0.1 to 0.7 mm. The length can be chosen anywhere between 0.5 and 5 mm.
As best seen in
Plate 9 operates as a spacer member, providing a predetermined distance between the receiver housings 2, 4. The distance there between corresponds to the thickness of the plate.
The thickness can be chosen such as to accommodate the acoustic mass, in this embodiment the outer diameter of tube 8. This allows the use of off-the-shelf receivers without the necessity of adapting the surface of the receiver housings or other additional measures to be able to position the acoustic mass between the receiver housings. Furthermore, the plate can be provided with means for attaching the receiver assembly to the inside of the casing of an earphone or hearing aid, thus functioning as a bracket member.
In the receiver assembly 1, the first receiver housing 2 preferably comprises a woofer transducer assembly and the second receiver housing 4 preferably comprises a mid-range transducer assembly or a tweeter transducer assembly. Thus, the receiver assembly operates as woofer-midrange or woofer-tweeter dual receiver assembly.
Referring to
The second receiver housing 4 houses a tweeter transducer assembly 34 designed for producing sounds in the upper region of the audio spectrum. The tweeter transducer assembly 34 comprises a motor assembly 35 driving a diaphragm 36 through a driving pin 37. The motor assembly 35 comprises a coil wire 38 wound around a bobbin 39, an armature 40 of the E-shaped type and a magnet assembly 41. The magnet assembly comprises a magnet housing 42 and a pair of magnets 43a, 43b. The second receiver housing 4 is made up of a case 44 and a cover 45. The case 44 is provided with connectors 46 for connecting a source of electric signals, representing e.g. audio signals for playback, to the transducer assembly 34.
The transducer assemblies operate as follows. Electric audio signals are transferred to each motor assembly 15, 35. Current running through the coils 18, 38 cause movement of the respective armatures 20, 40 which by means of the driving pins 17, 37 drive their respective diaphragms 16, 36. The induced vibrations of the diaphragms 16, 36 are transferred to the air located above the diaphragms. The vibrating air in the receiver housing constitute the sound waves produced by the receivers.
As explained above, between the first and second receiver housing 2, 4 the plate 9 is positioned with chamber 10 acoustically connected to the first sound outlet port 3. The sound produced by the woofer transducer assembly 14 in the first receiver housing 2 passes through the acoustic duct 7 and through the tube 8. The tube 8 acts as acoustic impedance and thus operates as acoustic low pass filter with a predetermined corner frequency corresponding to the design and dimensions of the tube 8. The filtered sound of the woofer assembly is joined with the sound of the tweeter assembly within the spout 6 and can travel further through a single sound channel.
Each of these embodiments and obvious embodiments thereof is contemplated as falling within the spirit and scope of the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/062724 | 6/29/2012 | WO | 00 | 12/31/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61505300 | Jul 2011 | US |
