Patent Description:
In the automotive industry, it is common to integrate loudspeaker assemblies in various locations in a car, such as in the dashboard, doors and pillars of the car. The pillars of the car may e.g. include side pillars and/or the "A-pillar" located between the front windscreen and the roof. The position and manner in which loudspeaker assemblies are incorporated into a car will in turn affect the way sound produced by those loudspeaker assemblies will be distributed within the car.

Many loudspeaker assemblies from the automotive industries are exposed to the outside environment and, even when not operational, may need to withstand potentially harmful external influences such as direct UV light, dust and direct contact by a driver or car passenger.

In the automotive industry, sound performance is often a key issue for many consumers, e.g. with many consumers choosing to spend additional money to upgrade the sound system in their car. Consequently, the design and integration of loudspeaker assemblies has become more and more important over time, and many car manufacturers are seeking to improve the performance and reliability of loudspeaker assemblies installed in their cars, and to give their sound systems a premium appearance. Recent developments along these lines include:.

Existing waveguide assemblies for use with loudspeakers in cars are typically integrated into the dashboard and/or A-pillar of the car, and have a fixed position in relation to the loudspeaker whose sound they are configured to guide.

The space available on and underneath a surface of a car in which a loudspeaker assembly may be installed (such a surface may be referred to herein as an "installation surface") may be limited in dimensions, for example a car dashboard may have limited space in which to accommodate a loudspeaker assembly.

<CIT> discloses a loudspeaker assembly incorporating an adjustable acoustic lens for controlling the directivity of sound emitted from a loudspeaker. The present inventor has observed that the design of this acoustic lens requires the lowering of the entire loudspeaker assembly into a car interior when it is non-operational (see <FIG> of this document), which necessarily requires the loudspeaker assembly to occupy a large volume of space within the car interior.

<CIT> discloses a modular loudspeaker intended to be used as a studio monitor, wherein the loudspeaker unit includes a high frequency radiating unit <NUM>, <NUM> (see <FIG>) the directional characteristic of which can be controlled by rotation of the high frequency radiating unit.

<CIT> describes a speaker device, installation body for speaker device, and mobile body having speaker device mounted thereon.

<CIT> describes controlling a speaker arrangement in a vehicle.

<CIT> describes a selectable loudspeaker-earphone.

<CIT> describes a dynamic voice coil speaker.

<CIT> describes a loudspeaker structure with a lighting effect.

<CIT> describes loudspeaker unit with source of light.

In a first aspect, the present invention provides:
A waveguide assembly for guiding sound, the waveguide assembly including:.

In this way, the interior of the waveguide assembly can be protected by the forward-facing surface of the waveguide assembly (formed by the fixed waveguide and the moveable waveguide) when the moveable waveguide is in its standby position, yet can allow sound to exit the waveguide assembly in a guided manner when the moveable waveguide is in the operational position.

Moreover, the waveguide assembly can achieve this effect with a smaller "build-in" height compared with other waveguide assemblies known to the present inventor, such as that disclosed by <CIT>, since with a waveguide assembly according to the first aspect of the invention, there is no need to retract the entire waveguide assembly into an installation surface in order to move the moveable waveguide to the standby position.

Moreover, if the waveguide assembly is installed in an installation surface (e.g. a surface of a car such as a dashboard), the forward-facing surface of the waveguide assembly (formed by the fixed waveguide and the moveable waveguide when the moveable waveguide is in the standby position) can be made to match that surface, therefore obscuring the interior of the waveguide assembly from view when the moveable waveguide is in the standby position.

In some examples, the waveguide assembly may include an installation surface including a cavity in which the waveguide assembly is installed. The forward-facing surface of the waveguide assembly (formed by the fixed waveguide and the moveable waveguide when the moveable waveguide is in the standby position) may be configured to match the appearance of the installation surface.

For example, the forward-facing surface of the waveguide assembly may be configured to be flush with respect to the installation surface. In this context, "flush" may be taken to mean not extending substantially beyond the installation surface.

For example the forward-facing surface of the waveguide assembly may be configured to provide a continuation of the installation surface, e.g. by substantially matching the contours of the installation surface.

For avoidance of any doubt, movement of the at least a part of the moveable waveguide in the rearwards direction along the primary axis of the waveguide assembly does not have to involve movement that is exactly parallel with the primary axis of the waveguide assembly, though parallel movement would generally make for a more straightforward implementation of the invention.

In some examples (which may be referred for brevity as "segmented moveable waveguide" examples), the moveable waveguide may include a plurality of moveable waveguide elements, each of which is movable with respect to the chassis between a respective standby position and a respective operational position. Each moveable waveguide element may be configured to be moved from its standby position to its operational position by that moveable waveguide element being retracted in the rearwards direction.

When all the moveable waveguide elements are in their respective standby positions, the moveable waveguide may be viewed as being in its standby position, and when all the moveable waveguide elements are in their respective operational positions, the moveable waveguide may be viewed as being in its operational position.

In a segmented moveable waveguide example, each moveable waveguide element may provide a respective waveguide surface configured to direct sound through the at least one opening formed between the fixed waveguide and the chassis when the moveable waveguide element is in its operational position. The waveguide surfaces of the moveable waveguide elements may together provide a dished surface (e.g. a frustoconical surface) when the moveable waveguide elements are in their operational positions. If the waveguide assembly is configured to guide sound in a full range of radial directions (see below), the waveguide surface of each moveable waveguide element may extend entirely around the primary axis of the waveguide assembly. If the waveguide assembly is configured to guide sound in a limited range of radial directions (see below), the waveguide surface of each moveable waveguide element may extend partially around the primary axis of the waveguide assembly.

In a segmented moveable waveguide example, each moveable waveguide element may be moveable between a respective standby position and a respective operational position along an axis parallel to the primary axis of the waveguide assembly.

In some examples (which may be referred for brevity as "flexible moveable waveguide" examples), the moveable waveguide may include a flexible waveguide element which is configured to flex so as to be movable with respect to the chassis between a standby position and an operational position. The flexible waveguide element may be configured to be moved from the standby position to the operational position by retracting at least a part of the flexible waveguide element in the rearwards direction.

In a flexible moveable waveguide example, an anchor portion of the flexible waveguide element may be attached to the chassis, preferably with a movable portion of the flexible waveguide element being attached to a movement mechanism of the waveguide assembly (see below). The flexible waveguide element is preferably configured to flex to allow movement of the movable portion of the flexible waveguide element. The anchor portion of the flexible waveguide element is preferably further away from the primary axis of the waveguide assembly than the movable portion of the flexible waveguide element.

In a flexible moveable waveguide example, a waveguide surface of the flexible waveguide element may be configured to provide a dished surface (e.g. a frustoconical surface) when the flexible waveguide element is in its operational position. If the waveguide assembly is configured to guide sound in a full range of radial directions (see below), the waveguide surface of the flexible waveguide element may extend entirely around the primary axis of the waveguide assembly. If the waveguide assembly is configured to guide sound in a limited range of radial directions (see below), the waveguide surface of the flexible waveguide element may extend partially around the primary axis of the waveguide assembly.

The moveable waveguide may be movable to one or more additional operational positions in which the moveable waveguide element is configured to allow sound to exit the cavity through the at least one opening. The additional operational positions may be part way between the standby position and the operational position. The directivity of the waveguide assembly may be different in each operational position.

The waveguide assembly may include a movement mechanism configured to move the moveable waveguide between the standby position and the operational position.

In a segmented moveable waveguide example, the movement mechanism may be configured to move all the moveable waveguide elements between their respective standby positions and their respective operational positions, e.g. one by one in sequence, or at the same time.

In a flexible moveable waveguide example, the moving mechanism may be configured to move the movable portion of the flexible waveguide element.

Various movement mechanisms could be envisaged by a skilled person in view of the disclosure herein.

By way of example, the movement mechanism may include a movement element connected to the moveable waveguide, wherein the movement mechanism is configured to move the movement element in the forwards direction and rearwards direction relative to the primary axis of the waveguide assembly.

By way of example, the movement mechanism may include one or more moveable pins configured to engage with one or more corresponding channels formed in a movement element or (for a segmented moveable waveguide example) in each moveable waveguide element. The movement mechanism may include a motor configured to move the one or more pins.

The movement element may extend around the primary axis of the waveguide assembly. It could be a ring-shaped element, for example.

The movement mechanism may include an electromechanical, electrodynamical or electromagnetic mechanism configured to move the movement element in the forwards direction and rearwards direction, for example.

The waveguide assembly may be configured to guide sound received by the cavity through the at least one opening formed between the fixed waveguide and the chassis in a full range of radial directions relative to the primary axis of the waveguide assembly (i.e. in a range of directions extending radially outwardly with respect to the primary axis and covering azimuth angles in the range <NUM> to <NUM>°, relative to a reference radial direction), or in a limited range of radial directions relative to the primary axis of the waveguide assembly (i.e. in a range of directions extending radially outwardly with respect to the primary axis and covering azimuth angles in the range <NUM> to X°, relative to a reference radial direction, where X is less than <NUM>°).

A limited range of radial directions may be useful e.g. if the waveguide assembly is installed in an installation surface where sound is not required in all radial directions relative to the primary axis of the waveguide assembly, e.g. in a car dashboard.

If the waveguide assembly is configured to guide sound in a full range of radial directions (see above), then the fixed waveguide may be shaped to have its rearward-most point positioned on the primary axis of the waveguide assembly, since this may help to facilitate guiding sound in the full range of radial directions.

If the waveguide assembly is configured to guide sound in a limited range of radial directions (see above), then the fixed waveguide may be shaped to have a curved (e.g. parabolic) surface positioned on the primary axis of the waveguide assembly, since this may help to facilitate guiding sound in the limited range of radial directions.

If the waveguide assembly is configured to guide sound in a full range of radial directions (see above), then the fixed waveguide may be held in place by one or more pillars connected to the chassis. The pillars are preferably small so as to minimise the effect on sound distribution. Such pillars may not be required if the waveguide assembly is configured to guide sound in a limited range of radial directions (see above).

The movable waveguide may include any one or more of the following:.

The waveguide assembly may include one or more light sources configured to provide illumination of the waveguide assembly.

Preferably, the one or more light sources are configured to provide illumination of the waveguide assembly when the moveable waveguide is in the operational position, optionally also when the moveable waveguide is in the standby position.

Thus, the light source may be configured to produce light (e.g. under control of a control unit) when the moveable waveguide is in the operational position, optionally also when the moveable waveguide is in the standby position.

By way of example, the one or more light sources may include any one or more of:.

In a second aspect, the present invention provides a loudspeaker assembly according to claim <NUM>.

Such loudspeakers are of course very well known.

The loudspeaker may be mounted in the chassis of the waveguide assembly with the diaphragm of the loudspeaker being configured to move along a loudspeaker axis which is parallel to (and preferably aligned with) the primary axis of the waveguide assembly, such that sound produced by the diaphragm is directly received by the cavity of the waveguide assembly with the sound received by the cavity of the waveguide assembly with the sound received by the cavity propagating in the forwards direction along the primary axis of the waveguide assembly.

However, it is also possible for the loudspeaker to be mounted in a loudspeaker chassis that is separate from the chassis of the waveguide assembly, e.g. with sound produced by the loudspeaker being guided by a further waveguide to the waveguide assembly, with the further waveguide being configured to guide sound produced by the loudspeaker to be received by the cavity of the waveguide assembly with the sound received by the cavity of the waveguide assembly propagating in the forwards direction along the primary axis of the waveguide assembly. In this case, the loudspeaker axis need not be parallel to the primary axis of the waveguide assembly.

If the loudspeaker is mounted in the chassis of the waveguide assembly (see above), the diaphragm may have an inner edge, an outer edge which is suspended from the chassis, and a diaphragm body which is between the inner and outer edges and extends around the primary axis of the waveguide assembly.

If the loudspeaker is mounted in the chassis of the waveguide assembly (see above), the drive unit may have a stationary part secured to the chassis and a translatable part secured to the inner edge of the diaphragm.

The diaphragm may have a dome shape, e.g. as is conventional for a tweeter.

The drive unit may be configured to move the diaphragm at frequencies in the range <NUM> to <NUM>, e.g. as is conventional for a tweeter.

Also disclosed herein is a vehicle including a waveguide assembly according to the first aspect of the invention or a loudspeaker assembly according to the second aspect of the invention. The vehicle may be a car, for example.

The present inventor has observed that it would be desirable to provide a waveguide assembly suitable for use in a car (and possibly other environments), wherein the including a moveable waveguide capable of transitioning between a standby position and an operational position such that:.

<FIG> show a first example loudspeaker assembly <NUM> in cross section.

The loudspeaker assembly includes a loudspeaker <NUM> and a waveguide assembly <NUM>.

The loudspeaker <NUM> includes a diaphragm and a drive unit (not shown) configured to move the diaphragm based on an input (electrical) signal so that the diaphragm produces sound based on the input signal.

In this example, the loudspeaker <NUM> is a tweeter, and the diaphragm has a dome shape, with the dome being concave with respect to the drive unit. In this example, the drive unit is configured to move the diaphragm at frequencies in the range <NUM> to <NUM>.

The waveguide assembly <NUM> is for guiding sound produced by the loudspeaker, and includes a chassis <NUM>, a fixed waveguide <NUM> and a moveable waveguide <NUM>.

The chassis <NUM> provides a cavity <NUM> configured to receive sound propagating in a forwards direction F along a primary axis <NUM> of the waveguide assembly <NUM>.

The fixed waveguide <NUM> is fixed with respect to the chassis <NUM> and positioned on the primary axis <NUM> of the waveguide assembly <NUM>, wherein the fixed waveguide <NUM> is spaced apart from the chassis <NUM> and is configured to guide sound received by the cavity <NUM> through an opening <NUM> formed between the fixed waveguide <NUM> and the chassis <NUM>. In this example, the fixed waveguide <NUM> has a dedicated shape with its lowest point above the centre of the loudspeaker <NUM> and on the primary axis <NUM> of the waveguide assembly <NUM>.

The moveable waveguide <NUM> is moveable with respect to the chassis <NUM> between:.

In this case the opening <NUM> is an annular (circular) opening, but in other examples it could have a different shape, e.g. oval.

In this example, the loudspeaker <NUM> is mounted in the chassis <NUM> of the waveguide assembly <NUM> with the diaphragm of the loudspeaker <NUM> being configured to move along a loudspeaker axis which is parallel to and aligned with (and therefore the same as) the primary axis <NUM> of the waveguide assembly <NUM>, such that sound produced by the diaphragm is directly received by the cavity <NUM> of the waveguide assembly <NUM> with the sound received by the cavity <NUM> of the waveguide assembly <NUM> propagating in the forwards direction F along the primary axis <NUM> of the waveguide assembly <NUM>. The loudspeaker <NUM> may be viewed as being below the fixed waveguide.

In this example (which may be referred for brevity as a "flexible moveable waveguide" example), the moveable waveguide <NUM> is a flexible waveguide element which is configured to flex so as to be movable with respect to the chassis between a standby position shown in <FIG> and an operational position shown in <FIG>.

As shown by <FIG>, an anchor portion <NUM> of the flexible waveguide element is attached to the chassis <NUM>, with a movable portion <NUM> of the flexible waveguide element being attached to a movement mechanism <NUM> of the waveguide assembly <NUM> (described in more detail with reference to <FIG>, below). The flexible waveguide element is configured to flex to allow movement of the movable portion <NUM> of the flexible waveguide element. The anchor portion <NUM> of the flexible waveguide element is located on a periphery of the flexible waveguide element, and is further away from the primary axis <NUM> of the waveguide assembly <NUM> than the movable portion <NUM> of the flexible waveguide element.

The moveable waveguide <NUM> is configured to be moved from the standby position to the operational position by retracting the movable portion <NUM> of the moveable waveguide <NUM> in a rearwards direction R along the primary axis <NUM> of the waveguide assembly <NUM>, wherein the rearwards direction R is opposite to the forwards direction F.

In this example, the flexible waveguide element is of elastic material, whose anchor portion <NUM> is connective to the chassis <NUM>.

In the standby position, the moveable waveguide element <NUM> protects the loudspeaker <NUM>, such that the loudspeaker <NUM> is not exposed to outside influence and in particular is protected from being touched by a user and protected from being damaged by external conditions (e.g. UV light).

A waveguide surface of the flexible waveguide element is configured to provide a dished surface <NUM> when the flexible waveguide element is in its operational position, as shown in <FIG>. In this example, the dished surface is frustoconical, but in other examples the dished surface may be curved or hyperbolic, for example.

In this example, the waveguide assembly <NUM> is configured to guide sound in a full range of radial directions, and the fixed waveguide <NUM> is shaped to have its rearward-most point positioned on the primary axis <NUM> of the waveguide assembly <NUM>, since this may help to facilitate guiding sound in the full range of radial directions.

The movement mechanism <NUM> is configured to move the moveable waveguide <NUM> between the standby position and the operational position.

<FIG> show the first example loudspeaker assembly <NUM> in cross section, whilst showing the movement mechanism <NUM> of the first example loudspeaker assembly <NUM> in more detail.

In this example, the movement mechanism <NUM> includes a movement element <NUM> connected to the flexible waveguide element, wherein the movement mechanism is configured to move the movement element <NUM> in the forwards direction F and rearwards direction R along the primary axis <NUM> of the waveguide assembly <NUM>, i.e. up and down as shown in <FIG>.

The movement element <NUM> may extend around the primary axis <NUM> of the waveguide assembly <NUM>. It could be a ring-shaped element, for example. The movement element <NUM> may connect to the flexible waveguide element radially inwards of the anchor portion <NUM>, e.g. towards the primary axis <NUM>.

The movement mechanism <NUM> may use various types of mechanisms, which may be located next to and/or below the loudspeaker <NUM>, for example. Such mechanisms may include, for example:.

Control of the movement mechanism <NUM> may be effected by a control unit (not shown), which may be located in the loudspeaker assembly or in an external unit connected to the loudspeaker assembly.

An alternative movement mechanism <NUM>' is shown in <FIG> and discussed below.

<FIG> illustrate different positions in which one or more light sources <NUM> configured to provide illumination of the waveguide assembly <NUM> of the first example loudspeaker assembly <NUM> when the moveable waveguide <NUM> is in the operational position. Direction of light is illustrated by arrows in <FIG>.

In <FIG>, a light source <NUM> is located under the diaphragm of the loudspeaker. In this case, the diaphragm may include a transparent or translucent material.

In <FIG>, a light source <NUM> is located on the fixed waveguide <NUM>, in this case on a side of the fixed waveguide surface which faces the diaphragm of the loudspeaker <NUM>.

In <FIG>, multiple light sources <NUM> are located on the chassis <NUM>, beside the loudspeaker <NUM> and underneath the moveable waveguide <NUM>. In this case, the flexible waveguide element may include a transparent or translucent material.

The one or more light sources <NUM> may be configured to provide illumination of the waveguide assembly when the moveable waveguide <NUM> is in the operational position as shown in <FIG>, optionally also when the moveable waveguide <NUM> is in the standby position.

The/each light source may be a one colour, or multiple colour, light source, and may be dimmable e.g. by an electronic control unit.

<FIG> show the first example loudspeaker assembly <NUM> in perspective view, incorporated into a dashboard <NUM> of a car.

In <FIG>, the moveable waveguide <NUM> is in the standby position, a forward facing surface of the waveguide assembly formed by the fixed waveguide <NUM> and the moveable waveguide <NUM> is flush with respect to (and provides a continuation of) the dashboard <NUM> (the dashboard <NUM> can be viewed as an installation surface, in this example).

Since the space available under the dashboard <NUM> is limited, the loudspeaker assembly <NUM> is designed to facilitate small dimensions so that the loudspeaker assembly <NUM> can fit into this limited space.

In <FIG>, the moveable waveguide <NUM> is in the operational position.

<FIG> shows that in this example the fixed waveguide <NUM> is held in place by three pillars <NUM> (only two of which are visible) connected to the chassis <NUM>. The pillars <NUM> are preferably small so as to minimise the effect on sound distribution. Such pillars <NUM> may not be required if the waveguide assembly <NUM> is configured to guide sound in a limited range of radial directions (see below).

As can be seen from <FIG>, in this example, the waveguide assembly <NUM> is configured to guide sound in a full range of radial directions when the moveable waveguide <NUM> is in the operational position, in other words it provides <NUM>° axial directivity of sound produced by the loudspeaker when the flexible waveguide element is in the operational position. This is achieved in part by the dished waveguide surface <NUM> of the flexible waveguide element extending entirely around the primary axis <NUM> of the waveguide assembly <NUM>.

The sound distribution of the loudspeaker assembly <NUM> when the moveable waveguide <NUM> is in the operational position is illustrated by the arrows in <FIG>.

The moveable waveguide <NUM> may have one or more additional operational positions (not shown) in which the directivity of the loudspeaker assembly <NUM> is altered, independent of the frequency of sound produced by the loudspeaker.

In this example, the position of the loudspeaker <NUM> within the chassis <NUM> is fixed but the position of the loudspeaker <NUM> within the chassis <NUM> may be altered or alterable to adapt the directivity of sound produced by the loudspeaker assembly <NUM>.

<FIG> show a second example loudspeaker assembly <NUM> in cross section.

The second example loudspeaker assembly <NUM> includes many features corresponding to those in the first example loudspeaker assembly. Similar features have therefore been given corresponding reference numerals and need not be explained further, except where further explanation is provided.

In this example (which may be referred for brevity as a "segmented moveable waveguide" example), the moveable waveguide <NUM> includes a plurality of moveable waveguide elements <NUM>, each of which is movable with respect to the chassis <NUM> between a respective standby position and a respective operational position. When all the moveable waveguide elements <NUM> are in their respective standby positions, the moveable waveguide <NUM> may be viewed as being in the standby position, and when all the moveable waveguide elements <NUM> are in their respective operational positions, the moveable waveguide <NUM> may be viewed as being in the operational position.

In this example, each moveable waveguide element <NUM> provides a respective waveguide surface configured to direct sound through the at least one opening <NUM> formed between the fixed waveguide <NUM> and the chassis <NUM> when the moveable waveguide element is in its operational position. The waveguide surfaces of the moveable waveguide elements may together provide a dished surface <NUM> (a frustoconical surface in the example shown) when the moveable waveguide elements <NUM> are in their operational positions.

In this example, the waveguide assembly <NUM> is configured to guide sound in a full range of radial directions, and the waveguide surface of each moveable waveguide element <NUM> extends entirely around the primary axis <NUM> of the waveguide assembly <NUM>.

In this example, each moveable waveguide element <NUM> is moveable between a respective standby position and a respective operational position along the primary axis <NUM> of the waveguide assembly <NUM>, i.e. up and down as shown in <FIG>.

<FIG> show the second example loudspeaker assembly <NUM> in cross section, whilst showing the movement mechanism <NUM> of the second example loudspeaker assembly <NUM> in more detail.

In this example, the movement mechanism <NUM> is configured to move all the moveable waveguide elements <NUM> between their respective standby positions and their respective operational positions.

In this example, the movement mechanism <NUM> includes a movement element <NUM> similar to that shown in <FIG>. The movement element <NUM> is attached to one of the moveable waveguide elements <NUM> (the centremost element, relative to the primary axis <NUM> of the waveguide assembly <NUM>). The moveable waveguide elements <NUM> are connected together so that movement of the moveable waveguide element to which the movement element <NUM> is attached causes movement of all of the moveable waveguide elements <NUM>. The connection between the moveable waveguide elements may be such that the moveable waveguide elements <NUM> at the same time as each other between their respective standby positions and their respective operational positions, or one by one in sequence between their respective standby positions and their respective operational positions. Such movement may create a pleasant visual effect for an observer.

An alternative movement mechanism <NUM>' is shown in <FIG> and discussed below.

<FIG> illustrate different positions in which one or more light sources <NUM> configured to provide illumination of the waveguide assembly <NUM> of the second loudspeaker assembly <NUM> when the moveable waveguide <NUM> is in the operational position. Direction of light is illustrated by arrows in <FIG>.

In <FIG>, a light source <NUM> is located under the diaphragm of the loudspeaker <NUM>. In this case, the diaphragm may include a transparent or translucent material.

In <FIG>, a light source 270is located on the fixed waveguide <NUM>, in this case on a side of the fixed waveguide surface which faces the diaphragm of the loudspeaker <NUM>.

In <FIG>, multiple light sources 270are located on the chassis <NUM>, beside the loudspeaker <NUM> and underneath the moveable waveguide <NUM>. In this case, one or more of the moveable waveguide elements <NUM> may include a transparent or translucent material.

The one or more light sources may be configured as described in connection with the first example loudspeaker assembly.

<FIG> show the second example loudspeaker assembly in perspective view, incorporated into a dashboard of a car.

In <FIG>, the moveable waveguide elements <NUM> are in their standby positions, and a forward facing surface of the waveguide assembly formed by the fixed waveguide <NUM> and the moveable waveguide elements <NUM> is flush with respect to (but does not provide a continuation of) the dashboard <NUM> (the dashboard <NUM> can be viewed as an installation surface, in this example).

In <FIG>, the moveable waveguide elements <NUM> are in their operational positions.

As can be seen from <FIG>, in this example, the waveguide assembly is configured to guide sound in a full range of radial directions when the moveable waveguide <NUM> is in the operational position, in other words it provides <NUM>° axial directivity of sound produced by the loudspeaker when the moveable waveguide elements <NUM> are in their operational positions. This is achieved in part by the waveguide surfaces of the moveable waveguide elements <NUM> extending entirely around the primary axis <NUM> of the waveguide assembly <NUM>.

The moveable waveguide elements may have one or more additional operational positions (not shown) in which the directivity of the loudspeaker assembly is altered, independent of the frequency of sound produced by the loudspeaker <NUM>.

<FIG> show a third example loudspeaker assembly <NUM> in cross section.

<FIG> shows the third example loudspeaker assembly <NUM> viewed from above, with arrows indicating the direction of sound as directed by a waveguide assembly <NUM> included in the third example loudspeaker assembly <NUM>.

The third example loudspeaker assembly <NUM> includes many features corresponding to those in the second example loudspeaker assembly <NUM>. Similar features have therefore been given corresponding reference numerals and need not be explained further, except where further explanation is provided.

A key difference between the third example loudspeaker assembly <NUM> and the second loudspeaker assembly <NUM> is that in the third loudspeaker assembly <NUM>, the waveguide assembly <NUM> is configured to guide sound received by the cavity through the opening <NUM> formed between the fixed waveguide <NUM> and the chassis in a limited range of radial directions relative to the primary axis <NUM> of the waveguide assembly <NUM> (i.e. in a range of directions extending radially outwardly with respect to the primary axis and covering azimuth angles in the range <NUM> to X°, relative to a reference radial direction, where X is less than <NUM>°). In this case, in a range of directions covering azimuth angles in the range <NUM>°-<NUM>°.

Since the waveguide assembly <NUM> is configured to guide sound in a limited range of radial directions, the waveguide surface of each moveable waveguide element <NUM> extends only partially around the primary axis of the waveguide assembly <NUM>.

Since the waveguide assembly <NUM> is configured to guide sound in a limited range of radial directions, the fixed waveguide <NUM> is shaped to have a curved (e.g. parabolic) surface positioned on the primary axis <NUM> of the waveguide assembly <NUM>, since this may help to facilitate guiding sound in the limited range of radial directions.

The movement mechanism <NUM> of the third examples loudspeaker assembly <NUM> is similar to that described with reference to the second example loudspeaker assembly <NUM>.

<FIG> illustrate different positions in which one or more light sources <NUM> configured to provide illumination of the waveguide assembly <NUM> of the third loudspeaker assembly <NUM> when the moveable waveguide <NUM> is in the operational position. Direction of light is illustrated by arrows in <FIG>.

In <FIG>, multiple light sources <NUM> are located on the chassis, beside the loudspeaker <NUM> and underneath the moveable waveguide <NUM>. In this case, one or more of the moveable waveguide elements <NUM> may include a transparent or translucent material.

The one or more light sources may be configured as described in connection with the first example loudspeaker assembly <NUM>.

<FIG> show the third example loudspeaker assembly <NUM> in perspective view, incorporated into a dashboard <NUM> of a car.

In <FIG>, the moveable waveguide elements <NUM> are in their standby positions, and a forward facing surface of the waveguide assembly formed by the fixed waveguide <NUM> and the moveable waveguide elements <NUM> is flush with respect to (but does not provide a continuation of) the dashboard <NUM> (the dashboard can be viewed as an installation surface, in this example).

As can be seen from <FIG>, in this example, the waveguide assembly <NUM> is configured to guide sound in a limited range of radial directions when the moveable waveguide <NUM> is in the operational position, in other words it provides an asymmetric sound distribution (relative to the primary axis) when the moveable waveguide elements <NUM> are in their operational positions. This is achieved in part by the waveguide surfaces of the moveable waveguide elements <NUM> only extending partly around the primary axis <NUM> of the waveguide assembly <NUM>.

Pillars are not required to support the fixed waveguide <NUM> in this example.

<FIG> show an alternative movement mechanism <NUM>' for use with the first example loudspeaker assembly <NUM>.

In this case, the movement mechanism <NUM>' includes a rotary servo motor <NUM>' configured to move a movement element <NUM>' which is attached to the moveable portion <NUM> of the moveable waveguide <NUM> of the previously described first example loudspeaker assembly <NUM>.

As shown in <FIG>, rotation of a rotor of the rotary servo motor <NUM>' causes movement of pins <NUM>' (in this case there are three pins, though only two can clearly be seen in the drawings) in corresponding channels <NUM>' formed in the movement element <NUM>'. This movement of the pins <NUM>' causes (through engagement with the channels <NUM>') the movement element <NUM>', and therefore the movable portion <NUM> of the moveable waveguide <NUM> to which the movement element <NUM>' is attached, to be retracted in the rearwards direction R, as illustrated by the thick arrow in <FIG>.

<FIG> show an alternative movement mechanism <NUM>' for use with the second example loudspeaker assembly <NUM>.

In this case, the movement mechanism <NUM>' includes a rotary servo motor <NUM>' configured to move each moveable waveguide element <NUM> of the previously described second example loudspeaker assembly <NUM>.

As shown in <FIG>, rotation of a rotor of the rotary servo motor <NUM>' causes movement of pins <NUM>' (in this case there are three pins, though only two can clearly be seen in the drawings) in corresponding channels <NUM>' formed in each of the moveable waveguide elements <NUM>. This movement of the pins <NUM>' causes (through engagement with the channels <NUM>') each moveable waveguide element <NUM> to be retracted in the rearwards direction R. By appropriately shaping the channels respectively formed in each moveable waveguide element <NUM>, the movement of the moveable waveguide elements <NUM> and the extent of such movement in the rearwards direction R can be controlled, e.g. so as to cause the moveable waveguide elements <NUM> to move one by one in sequence between their respective standby positions and their respective operational positions, or so as to move at the same time as each other between their respective standby positions and their respective operational positions. In the illustrated example, the channels <NUM>' are configured to cause the moveable waveguide elements <NUM> to move at the same time as each other), as illustrated by the thick arrow in <FIG>. Of course, in all the examples discussed above, the geometry of the fixed and moveable waveguides can be optimised and varied according to required sound performance and other design requirements.

A loudspeaker as described above may be used in contexts other than in a car, e.g. in the consumer industry, in the architectural industry (e.g. integrated into a ceiling or wall), in the home entertainment industry, or in the PA industry.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the invention as defined by the appended claims.

Claim 1:
A waveguide assembly (<NUM>, <NUM>, <NUM>) for guiding sound, the waveguide assembly (<NUM>, <NUM>, <NUM>) including:
a chassis (<NUM>, <NUM>, <NUM>) that provides a cavity (<NUM>) configured to receive sound propagating in a forwards direction along a primary axis (<NUM>, <NUM>, <NUM>) of the waveguide assembly (<NUM>, <NUM>, <NUM>);
a fixed waveguide (<NUM>, <NUM>, <NUM>) that is fixed with respect to the chassis (<NUM>, <NUM>, <NUM>) and positioned on the primary axis (<NUM>, <NUM>, <NUM>) of the waveguide assembly (<NUM>, <NUM>, <NUM>), wherein the fixed waveguide (<NUM>, <NUM>, <NUM>) is spaced apart from the chassis (<NUM>, <NUM>, <NUM>) and is configured to guide sound received by the cavity (<NUM>) through at least one opening (<NUM>, <NUM>, <NUM>) formed between the fixed waveguide (<NUM>, <NUM>, <NUM>) and the chassis (<NUM>, <NUM>, <NUM>);
a moveable waveguide (<NUM>, <NUM>, <NUM>) that is moveable with respect to the chassis (<NUM>, <NUM>, <NUM>) between:
a standby position in which the moveable waveguide (<NUM>, <NUM>, <NUM>) is configured to obstruct the at least one opening (<NUM>, <NUM>, <NUM>) and, together with the fixed waveguide (<NUM>, <NUM>, <NUM>), form a forward-facing surface of the waveguide assembly (<NUM>, <NUM>, <NUM>);
an operational position in which the moveable waveguide (<NUM>, <NUM>, <NUM>) is configured to allow sound to exit the cavity (<NUM>) through the at least one opening (<NUM>, <NUM>, <NUM>);
wherein the moveable waveguide (<NUM>, <NUM>, <NUM>) is configured to be moved from the standby position to the operational position by retracting at least a part of the moveable waveguide (<NUM>, <NUM>, <NUM>) in a rearwards direction along the primary axis (<NUM>, <NUM>, <NUM>) of the waveguide assembly (<NUM>, <NUM>, <NUM>), wherein the rearwards direction is opposite to the forwards direction.