Patent Application
20100061574
The present invention relates to audio systems.
A crucial aspect of home cinema systems is the nature and quality of the sound reproduction. An important feature of good home cinema sound reproduction is so-called “surround sound” or “ambient sound”, i.e. the illusion that the reproduced sound is emanating from all around the listener rather than from specific discrete sources (i.e. the loudspeakers). Conventionally, surround sound loudspeakers are positioned in a configuration around the viewer/listener so that the viewer/listener is physically surrounded by a large number of speakers.
At the present time, most digital versatile discs (DVDs) and super audio compact discs (SACDs) are produced using five, six or seven channels suitable for creating surround sound reproduction, for example, for home cinema applications. Particular versions of five, six and seven channel systems are the Dolby (trade mark) 5.1, 6.1 and 7.1 systems, for example. (In each case, the first digit refers to the number of main channels, and the second digit refers to an additional low frequency effects channel.)
In the five-channel system there is one centre loudspeaker that generally carries most of the dialogue, and may also carry parts of the soundtrack (music and sound effects) of the film. Front left and front right loudspeakers are connected to carry most of the soundtrack and may carry parts of the dialogue. A pair of surround sound loudspeakers is placed on either side of the viewer/listener (called, respectively, the left surround and right surround loudspeakers) to provide the surround sound and ambient effects, and a subwoofer can be used to reproduce the low and very low frequency effects. (The ambient and surround sound effects are also known as the diffuse effect as the sound appears not to emanate from one particular spatial point.)
In the six-channel system a centre back loudspeaker provides an additional surround sound channel output. In the seven-channel system, instead of a centre back loudspeaker there are left back and right back loudspeakers located behind the viewer/listener.
A disadvantage of these systems is that they require a large quantity of wiring and a large number of individual loudspeakers. This may not be aesthetically pleasing, may present practical difficulties in terms of positioning and space-consumption, and may require the purchaser of such systems to invest in special under-floor wiring, for example. In addition to the expense of the installation of the system there is the expense of purchasing a large number of individual speakers.
With the advent of multi-channel audio discs, the number of loudspeakers is likely to increase, thus causing further practicality problems and expense.
The present invention seeks to alleviate at least some of the problems of conventional surround sound reproduction installations, for example. The invention particularly seeks to avoid the need for a separate loudspeaker for each channel. The invention also seeks to avoid the need for positioning each loudspeaker at a particular location with respect to the listener/viewer according to the particular channel routed to that loudspeaker. Thus, the invention seeks to avoid at least some of the practicality problems of known systems. It is to be understood that the invention is not limited to SACD or home cinema applications, or to surround sound in general, although such applications will be particularly suited to the invention.
Accordingly, a first aspect of the present invention provides an audio system comprising three or more loudspeaker units and a source of four or more audio channels, wherein each loudspeaker unit comprises a monopole loudspeaker and a dipole loudspeaker.
Preferably, the monopole loudspeaker comprises a pistonically driven diaphragm loudspeaker. The dipole loudspeaker preferably comprises a resonant panel loudspeaker.
A second aspect of the invention accordingly provides an audio system comprising three or more loudspeaker units and a source of four or more audio channels, wherein each loudspeaker unit comprises a pistonically driven diaphragm loudspeaker and a resonant panel loudspeaker.
Preferably there are five or more audio channels and/or four or more loudspeaker units.
The resonant panel may be generally (especially substantially) planar. The plane of the resonant panel preferably lies generally in the same orientation as an axis along which the diaphragm is pistonically driven. More preferably, the axis along which the diaphragm is pistonically driven lies substantially in the plane of the resonant panel.
Advantageously, the number of loudspeaker units is less than the number of audio channels.
Preferably, the loudspeaker units of the system collectively are arranged to emit sounds in response to signals carried by the audio channels.
Each audio channel may have a respective designated intended output position relative to a listener. For example, the audio channels may comprise one or more (or all) of the following channels: front left; front centre; front right; left surround (side); right surround (side); back left; back centre; back right.
In preferred embodiments of the invention, any loudspeaker of any of the loudspeaker units may be arranged to emit sounds in response to signals carried by one or more of the audio channels. More preferably, any loudspeaker of any of the loudspeaker units may be arranged to emit sounds in response to signals carried by any of the audio channels. Advantageously, for each respective audio channel, the loudspeaker or loudspeakers from which sounds may be emitted in response to signals carried by that channel, may be selected at will.
Advantageously, in use, each loudspeaker unit may be situated at a respective position relative to a listener. The audio system preferably is arranged such that, for any position relative to a listener (e.g. to the front and left of the listener) at which a loudspeaker unit is situated in use, sounds emitted in response to signals carried by the audio channel for which the designated intended output position (e.g. the front left audio channel) corresponds most closely to the position of that loudspeaker unit are emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit. For example, the audio system may be arranged such that, if a loudspeaker unit is situated at, or approximately at, a position relative to a listener that corresponds to a designated intended output position of an audio channel, then sounds emitted in response to signals carried by that channel are emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit. Even more preferably, those sounds are emitted from the monopole loudspeaker only or pistonically driven diaphragm loudspeaker only of that loudspeaker unit.
If a loudspeaker unit of the audio system is not situated at, or not approximately at, a position relative to a listener that corresponds to a designated intended output position of a particular audio channel, then sounds emitted in response to signals carried by that channel preferably are not emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit.
If a loudspeaker unit is not situated at, or not approximately at, a position relative to a listener that corresponds to a designated intended output position of a particular audio channel, then sounds emitted in response to signals carried by that channel preferably may. be selected to be emitted from the dipole loudspeaker or resonant panel loudspeaker of that loudspeaker unit.
Preferably, one or more of the audio channels is a surround sound or ambient sound channel, and the system is arranged such that sounds emitted in response to signals carried by such channel(s) are emitted from one or more of the dipole loudspeakers or resonant panel loudspeakers.
A third aspect of the invention provides an audio-visual system comprising an audio system according to the first or second aspect of the invention, and a visual display means.
A fourth aspect of the invention provides a method of installing an audio system or an audio-visual system according to the invention, comprising situating each loudspeaker unit at a respective position relative to a listener.
The method preferably comprises selecting, for each respective audio channel, the loudspeaker or loudspeakers from which sounds may be emitted in response to signals carried by that channel.
Some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, of which:
In the example shown in
Referring to the pistonically driven diaphragm loudspeaker 7, the terms “pistonic loudspeaker” and “pistonically driven diaphragm loudspeaker” in this specification refer to a loudspeaker in which a diaphragm moves in a piston-like motion as a generally rigid whole for at least part of its operating frequency range (for example up to approximately 700 Hz). The exemplary pistonically driven diaphragm loudspeaker 7 comprises a generally conical diaphragm 9 and a driver 11 for the diaphragm 9. The driver 11 can be an electro-mechanical transducer, e.g. a moving coil transducer, but other types of drivers can also be used. The pistonically driven diaphragm loudspeaker 7 preferably provides coherent sound reproduction (whereas the resonant panel loudspeaker 21 preferably provides diffuse surround sound reproduction). Most preferably, the diaphragm loudspeaker 7 functions as a monopole acoustic source, and preferably the resonant panel loudspeaker 21 functions as a diffuse dipole acoustic source.
For loudspeaker units used in the present invention, the plane of the resonant panel loudspeaker 21 may, for example, be generally parallel to the axis A-A along which the diaphragm 9 is pistonically driven. Preferably, however, the plane of the resonant panel 3 and said axis are generally in line with each other (i.e. the axis preferably lies in generally the same plane as the panel). Preferably the plane of the panel 3 lies substantially in the same orientation as the axis along which the diaphragm 9 is pistonically driven. Consequently, the panel 3 and the axis preferably are either substantially parallel to each other or substantially in line with each other, i.e. the axis preferably lies in substantially the same plane as the panel. This is shown schematically in
Preferably, the resonant panel loudspeaker 21 is located relative to the pistonically driven diaphragm loudspeaker 7 such that the emission of the acoustic radiation from the diaphragm loudspeaker 7 is substantially unimpeded by the resonant panel loudspeaker 21. Advantageously, the resonant panel loudspeaker 21 may be located above, below, to the side, or behind the diaphragm loudspeaker 7. Most preferably the resonant panel speaker 21 is located behind the diaphragm loudspeaker 7. In
Preferably the resonant panel loudspeaker 21 is arranged to radiate sound from both opposite major surfaces of the panel 3 simultaneously. A loudspeaker unit 20 according to the present invention has the advantage that by orientating the plane of the resonant panel loudspeaker 21 so that it is in generally the same orientation as the axis of the pistonically driven diaphragm loudspeaker 7 the resonant panel loudspeaker 21 normally produces a generally “figure-of-eight” acoustic radiation pattern by radiating sound from both opposite major surfaces of the panel 3 with the “null” of the radiation pattern generally coincident with the axis of the diaphragm loudspeaker 7. Consequently, the use of a resonant panel loudspeaker 21 in this orientation produces the type of acoustic radiation pattern generally required of surround sound. Additionally, and most advantageously, resonant panel loudspeakers tend to produce diffuse acoustic radiation, which is ideal for creating ambient surround sound. These two characteristics in combination mean that the resonant panel loudspeaker 21 of the loudspeaker unit 20 according to the present invention generally provides an extremely effective surround sound loudspeaker system.
An enclosure for the loudspeaker unit 20 is omitted from
Each loudspeaker unit 20 may comprise more than one pistonically driven diaphragm loudspeaker 7 and/or more than one resonant panel loudspeaker 21. For example, the function of the pistonic loudspeaker 7 may be carried out by a plurality of pistonic loudspeakers (e.g. with each such loudspeaker dedicated to a respective frequency range). The pistonically driven diaphragm loudspeaker 7 may, for example, comprise a compound loudspeaker of the type disclosed in U.S. Pat. No. 5,548,657, the entire disclosure of which is incorporated herein by reference.
The system shown in
It will be understood from the above described example of audio channel allocations according to loudspeaker unit position and according to loudspeaker type, that an audio system or an audio-visual system according to the invention preferably is arranged such that, for any position relative to a listener at which a loudspeaker unit is situated in use, sounds emitted in response to signals carried by the audio channel for which the designated intended output position (e.g. front left, front right, etc.) corresponds most closely to the position of that loudspeaker unit preferably are emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit. For example, the audio system may be arranged such that, if a loudspeaker unit is situated at, or approximately at, a position relative to a listener that corresponds to a designated intended output position of an audio channel (e.g. front left), then sounds emitted in response to signals carried by that channel (e.g. front left) are emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit. Even more preferably, those sounds are emitted from the monopole loudspeaker only or pistonically driven diaphragm loudspeaker only of that loudspeaker unit.
However, if a loudspeaker unit of the audio system is not situated at, or not approximately at, a position relative to a listener that corresponds to a designated intended output position of a particular audio channel (e.g. the loudspeaker unit is situated front left, whereas the particular audio channel being considered is the left side surround/ambient channel), then sounds emitted in response to signals carried by that channel preferably are not emitted from the monopole loudspeaker or pistonically driven diaphragm loudspeaker of that loudspeaker unit. Instead, sounds emitted in response to signals carried by that channel (e.g. the left side surround/ambient channel) may be allocated such that they are emitted from the dipole/resonant panel loudspeaker of that loudspeaker unit (positioned front left).
Preferably, the rear/side audio channels are allocated to the dipole/resonant panel loudspeakers situated at the front and at the side/rear and also allocated to the monopole/diaphragm loudspeakers situated at the rear/side. The balance of the front/rear channels between loudspeakers preferably will be varied depending upon the positions of the loudspeaker units. In particular, if the rear/side loudspeaker units are at the side, then the side channels preferably are allocated to the monopole/diaphragm loudspeakers and the rear channels are allocated to the dipole/resonant panel loudspeakers. Alternatively, if the rear/side loudspeaker units are behind the listener, then the side channels preferably are allocated to the dipole/resonant panel loudspeakers and the rear channels are allocated to the monopole/diaphragm loudspeakers. Such allocations, and all of the audio channel allocations described in this specification, preferably may be proportional, that is a proportion of a particular channel may be allocated to a particular loudspeaker, and another proportion of the channel may be allocated to one or more other loudspeakers. Depending upon the desired balance and room positioning, the dipole/resonant panel loudspeakers at the front may have some side signal applied to them. The dipole/resonant panel loudspeakers preferably are used to provide an ambient effect for the surround signals and the rear monopole/diaphragm loudspeakers preferably are used for the “sound effects” signals.
The listener/viewer preferably can allocate the audio channels to the various loudspeakers of the loudspeaker units with at least partial freedom, but more preferably with complete freedom, at will. Alternatively, however, the system may itself allocate (e.g. under computer control without direct intervention by the listener/viewer) the audio channels to the various loudspeakers of the loudspeaker units. Such allocation (whether by the listener/viewer, or by the system itself) may, for example, be an “active” allocation,.that is, the allocations or distributions of channels between the loudspeakers may be changed (e.g. continuously or periodically) during the operation of the system. Alternatively, the allocations may be fixed.
The loudspeaker unit shown in
As can clearly be seen in
The present invention has been described in considerable detail with reference to certain preferred versions thereof; however, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0508616.0 | Apr 2005 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB2006/001580 | 4/28/2006 | WO | 00 | 11/30/2009 |
