Patent Application
20230276176
The present invention relates to a speaker unit comprising a speaker frame, two membranes arranged in the speaker frame, a first membrane of the two membranes having a major acoustic radiation direction substantially perpendicular to a major plane of the speaker unit, and a second membrane of the two membranes having a secondary acoustic radiation direction different from the major acoustic radiation direction, and two drive units positioned within the speaker frame and attached to the first and second membranes, respectively.
US patent publication US2010/0232637 discloses a speaker device having two opposed speakers positioned in a speaker box, wherein the two speakers are mechanically coupled and the speaker box is provided with an opening portion.
US patent publication US2007/0154044 discloses a loudspeaker system having multiple spherical enclosures, each housing a pair of (opposed) transducers.
US patent publication US2012/237077 discloses an opposing dual-vented woofer system. A vented speaker driver assembly is described utilizing a speaker driver having a pole piece that defines therein a vent that is not covered by a dust cap. The frame of the speaker driver is configured to be mounted to a structure's surface such that the pole piece of the driver is located within the structure's interior space. The vented speaker driver is configured to be utilized in a back-to-back vented driver assembly wherein the sound of more than one speaker driver is achieved in a footprint of only one driver and with minimized generation of physical vibrations from the assembly.
US patent publication U.S. Pat. No. 5,821,471 discloses speaker housings having various configurations, e.g. for directing backward aimed sound from a membrane in a housing towards a front side of the speaker.
International patent publication WO2019/086357 discloses a speaker unit having two opposing moving membranes.
International patent publication WO02/052892 discloses a speaker unit having a drive unit provided with air ducts.
The present invention seeks to provide a speaker unit having an improved performance in space efficiency, power, and freedom of air displacement directivity, as compared to existing speaker units. The speaker unit further provides for improved cooling of electronic components of the speaker unit in a further group of embodiments.
According to the present invention, a speaker unit as defined above is provided, wherein the first and second membranes are arranged in opposite configuration in the speaker frame and the secondary acoustic radiation direction is opposite to the major acoustic radiation direction, wherein the first and second membranes are coaxially aligned along the major and opposite second acoustic radiation direction, and wherein the two drive units are positioned coaxial to each other at the same height in the speaker frame and laterally displaced from the membranes in a side-by-side arrangement therewith. The speaker unit further comprises an acoustic duct providing a closed acoustic channel from the second membrane in the secondary acoustic radiation direction to a secondary surface of the speaker unit, the secondary surface being located in a same plane as the major plane of the speaker unit.
The present invention embodiments have a structure and mutual element orientation allowing to provide a self-balancing, more space efficient speaker unit for dual membrane units which have air displacement direction restrictions (e.g. vehicle doors, in-ceiling speakers, TV, or any speaker with single-sided air displacement restrictions).
The present invention will be discussed in more detail below, with reference to the attached drawings, in which
The present invention will be explained in detail with reference to some exemplary embodiments shown in the drawings, which are only intended to show embodiments of the invention and not to limit the scope. The scope of the invention is defined in the annexed claims and by its technical equivalents. A person skilled in the art will understand that features, components, elements, etc. explicitly used to explain the invention can be substituted by technical equivalents unless otherwise stated. Moreover, separate features of different embodiments can be combined, even if not explicitly shown in the drawings or explained in the specification, unless such combination is physically impossible. The present invention will be discussed in more detail below, with reference to some drawings. The examples and embodiments described herein serve to illustrate rather than to limit the invention. The person skilled in the art will be able to design alternative embodiments without departing from the scope of the claims. Reference signs placed in parentheses in the claims shall not be interpreted to limit the scope of the claims. Items described as separate entities in the claims or the description may be implemented as a single or multiple hardware items combining the features of the items described.
It is to be understood that the invention is limited by the annexed claims and its technical equivalents only. In this document and in its claims, the verb “to comprise” and its conjugations are used in their non-limiting sense to mean that items following the word are included, without excluding items not specifically mentioned. In addition, reference to an element by the indefinite article “a” or “an” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article “a” or “an” thus usually means “at least one”.
In the speaker unit embodiments of the present invention, two examples of which are shown in the
In general, the present invention relates to a speaker unit 1 comprising a speaker frame 9, (at least) two membranes 7, 8, (at least) two drive units 2, and an acoustic duct 6. The two membranes 7, 8 are arranged in the speaker frame 9, a first membrane 7 of the two membranes having a major acoustic radiation direction A substantially perpendicular to a major plane 9a of the speaker unit 1, and a second membrane 8 of the two membranes having a secondary acoustic radiation direction B different to the major acoustic radiation direction A. Note that the first and second membrane 7, 8 thus move up and down in the indicated acoustic radiation direction A, B, but that the sound from the speaker has a direction away from the membranes 7, 8. The two drive units 2 are positioned within the speaker frame 9 and attached to the two membranes 7, 8, the two drive units 2 being positioned coaxial to each other at the same height in the speaker frame 9. An acoustic duct 6 is present and provides a closed acoustic channel from the second membrane 8 in the secondary acoustic radiation direction B to a secondary surface 6a of the speaker unit 1, the secondary surface 6a being located in a same plane as the major plane 9a of the speaker unit 1. The acoustic duct 6 is thus arranged to redirect acoustic waves from the second membrane 8 to radiate in the same plane as the first membrane 7.
In a more specific embodiment, the two membranes 7, 8 are arranged in opposite configuration in the speaker frame, and the secondary acoustic radiation direction B is opposite to the major acoustic radiation direction A (i.e. 1800).
The speaker frame 9 may be arranged as a combination of top, bottom and four side walls, optionally provided with apertures to reduce overall weight of the speaker unit 1, as shown in the views of
In this embodiment, the secondary surface 6a is located adjacent to a front surface of the speaker frame 9. The acoustic energy emanating from the second membrane 8 is redirected to the secondary surface 6a, and thus provided adjacent to the acoustic energy emanating from the first membrane 7, both in the major acoustic radiation direction A.
In the cross sectional view of
In a group of embodiments similar to the embodiment shown in
As shown most clearly in the cross sectional view of
In the exemplary embodiment shown in
In prior art speaker systems, the dual opposing driver principle in the classic sense is used, wherein drivers are placed in a back-to-back position. The benefit of this architecture is that the opposing drivers cancel out mechanical vibrations of the enclosure of the speaker unit. Because of this cancellation, the enclosure is affected significantly less by the movement of the drivers, even if the enclosure is relatively light, of low rigidity and or small in relation to the drivers. The downside in these earlier prior art systems employing back-to-back positioned drivers, is that the footprint is bound by at least two times the depth of the identical drivers.
Converging the drivers into coaxially positioned drive units 2 is an efficient manner for decreasing the minimum amount of volume needed in the speaker design, as for example described in the published patent application WO2019/086357 of the present applicant, which is incorporated herein by reference. A further development of loudspeaker devices possibly having a low profile are described in International patent application WO2019/117706 of the present applicant, which is also incorporated herein by reference. The drive units 2 as applied in the present invention embodiments may also be implemented as the units described in International patent application WO2018/056814, which is also incorporated herein by reference.
It is noted that currently applied damper and port solutions are not usable in the converged driver architecture described above. When the membranes 7 make an excursion inwards (towards each other), the variable distance between the membranes 7 would create a problematic situation for a static centred port as e.g. known from US patent publication U.S. Pat. No. 8,452,041.
It is noted that the acoustic duct 6 as used in the present invention embodiments has a functionality which is acoustically and mechanically different from a ported speaker enclosure, where the port is used as a way of enhancing the bass performance or providing a band pass filter. Also, the air displacement which is redirected, comes from the side of the membrane 8 movement which is acoustically in phase and mechanically out of phase with the side of the other membrane(s) 7 which is (are) moving in free air. The acoustic duct 6 purpose is to redirect the air displacement of the second membrane 8 with as little effect on the acoustic output of the redirected membrane's air displacement as possible.
The speaker unit 1 may comprise a vented frame element, e.g. as top plate of the speaker frame 9 as shown in
According to the present invention, various embodiments of a speaker unit 1 are provided, wherein each of a plurality of drive units 2 comprises at least one voice coil 3 and a magnet assembly 4 with at least two magnets. To direct all air displacement towards a single surface or several surfaces providing the major acoustic radiation direction A, the acoustically in phase air displacement of at least one of the two membranes 7, 8 is redirected using the acoustic duct 6 towards a surface 6a which is not equal to the acoustically in phase outward excursion direction of the membrane 8 of which the air displacement is being redirected.
The combination of speaker frame 9, two membranes 7, 8 and drive units 2, 2′ of the present invention embodiments could be placed in a loudspeaker cabinet, having at least one acoustic duct 6 which enable both membranes 7, 8 to displace air to free air (i.e. the speaker unit 1 exterior), where air displacement of at least one membrane 8 is guided through the acoustic duct 6 towards a side of the speaker unit 1 which is not equal to the outward excursion direction of the redirected membrane 8.
In a further embodiment, the first membrane 7 and second membrane 8 are cone shaped (see the
In order to obtain an even more efficient speaker unit 1, the acoustic duct 6 has an inner surface arranged to guide acoustic waves in a further embodiment. This may be obtained by e.g. using a suitable (plastic) material with a proper acoustic properties.
In a further embodiment, the speaker unit 1 has an inner space delimited by the speaker frame 9 and the two membranes 7, 8, the two drive units 2 being positioned in the inner space. The voice coil 3 and magnet assembly 4 of the drive units 2 are then isolated from environmental air, and from the acoustic waves generated by the membranes 7, 8.
In order to obtain an efficient speaker unit 1, wherein also the second membrane 8 contributes significantly to the sound produced by the speaker unit 1, a smallest cross section of the acoustic channel 6 is larger than 1 cm2 in a further embodiment. Such a dimensional limit will provide a sufficiently low acoustical damping to obtain a high enough sound pressure level emanating from the secondary surfaces 6a.
Alternatively, or additionally, in a further embodiment, a smallest width of the acoustic channel 6 is selected to be larger than 5 mm. E.g. a width w of the secondary surface 6a as indicated in the embodiment shown in
With respect to the previous two embodiments, it is noted that in alternative embodiments, where the speaker unit 1 is a very small speaker unit, the smallest cross section and/or smallest width can even be smaller.
In even further embodiments, a frontal surface area the secondary surface 6a is at least 10% of a frontal surface area of the second membrane 8. This has the effect that a sufficient high part of the sound energy produced by the second membrane 8 is guided towards the front side of the speaker unit 1, and contributes to the total sound pressure level that can be generated by the speaker unit 1.
To enable the present invention speaker unit 1 to be applied in many applications, such as in vehicle doors, as in-ceiling speaker, in television apparatus, etc., a total height h of the speaker unit 1 (see embodiment shown in
In further advantageous embodiments, the speaker unit 1 of the present invention also provides for improved cooling of internal or external components of the speaker unit 1, such as the (at least) two drive units 2, but also e.g. one or more electronic components for driving the two drive units 2. To obtain this effect, at least part of the acoustic duct 6 is made from thermally conductive material.
Referring to
To prevent excessive heat build-up within the speaker frame 9 when the speaker unit 1 is in operation, an embodiment is provided wherein the acoustic duct 6 (e.g. first part 6b and/or the second part 6c) comprise thermally conductive material. This embodiment allows heat being generated in the speaker frame 9 by e.g. the two drive units 2 to be dissipated through improved thermal conductivity of the first and second parts 6b, 6c of the acoustic duct 6. Alternatively or additionally, the acoustic duct 6 can now also be used for cooling externally mounted components (e.g. electronic components) by using the moving air inside the acoustic duct 6 during operation (even if actual volume is limited, there is still exchange of heat energy via the air moving in the acoustic duct 6. So in this embodiment the first and second parts 6b, 6c now act as thermal heat sinks for the speaker unit 1.
It is worth noting that, since the second part 6b may comprise one, two, three or all four sides of the speaker frame 9, that a desired level of heat dissipation can be achieved by choosing which of the one, two, three and/or four sides should comprise thermally conductive material.
Thermal performance of the speaker unit 1 may be improved by considering an embodiment wherein the acoustic duct 6 further has a third part 6d as shown in
By taking the above into account, a combined embodiment can be envisage wherein the acoustic duct 6 further has the third part 6d arranged opposite the second membrane 8 at a predetermined distance therefrom, and wherein the first part 6b, the second part 6c and/or the third part 6d comprise thermally conductive material.
In an exemplary embodiment, the thermally conductive material exhibits a thermal conductivity of at least 100 W/m*K. So when the first part 6b, the second part 6c and/or the third part 6d comprise e.g. aluminium or copper, then the thermal conductivity of at least 100 W/m*K would be achieved.
In an embodiment, as shown in
Because the one or more electronic components 10a, 10b, 10c may generate heat, an embodiment is conceivable wherein the one or more electronic components 10a, 10b, 10c are mounted in thermal contact with the acoustic duct 6 (e.g. on the first part 6b, the second part 6c and/or the third part 6d each of which comprises thermally conductive material accordingly. This embodiment effectively allows the one or more electronic components 10a, 10b, 10c to use the acoustic duct 6 as a thermal heat sink, wherein heat from the one or more electronic components 10a, 10b, 10c is dissipated through the thermally conductive first part 6b, second part 6c and/or third part 6d.
It is worth noting that also air cooling of the one or more electronic components 10a, 10b, 10c may occur in the embodiment wherein the one or more electronic components 10a, 10b, 10c are mounted inside the acoustic duct 6 on the thermally conductive first part 6b, second part 6c and/or third part 6d. So when the speaker unit 1 is in use, movement of air through the acoustic duct 6 will cool the one or more electronic components 10a, 10b, 10c arranged therein. Note that this air cooling also occurs when none of the first part 6b, second part 6c and/or third part 6d are thermally conductive.
In even further embodiments, also a further part of the speaker unit 1 which is in thermal contact with the acoustic duct 6 can be made from thermally conductive material, such as a front surface of the speaker frame 9, allowing external components that need cooling to be mounted thereon.
The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/071790 | Aug 2020 | WO | international |
| 20205819.4 | Nov 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/071285 | 7/29/2021 | WO |
