On-wall loudspeaker and mounting apparatus

An on-wall loudspeaker and mounting apparatus includes an enclosure, a loudspeaker driver mounted in the enclosure, brackets of equal length and attachable to a wall, arms of equal length pivotably attached to the brackets and pivotably attached to the enclosure, each arm pivotable perpendicular to the wall. A movement of a cone in the driver is parallel to the pivoting of the arms when an alternating current signal is applied to the driver. The present invention mitigates vibrations transmitted to walls and other building structures, and provides improved means for reproducing low frequencies below a range of conventional loudspeakers.

TECHNICAL FIELD

The present invention relates to loudspeakers and in particular to a loudspeaker mountable on a wall and an apparatus for mounting thereon.

BACKGROUND OF THE INVENTION

Currently available media such as CD (compact disc) and DVD (digital video disc) formats that have audio content that exceeds the capabilities of most conventional loudspeakers, especially at lower or bass frequencies. Typical formats such as DTS® (digital theater system) provide 5.1 channels of compressed audio content. An LFE (low frequency effect) channel (the “0.1” channel) may contain audio content as low as 1 Hz. Even after compression and decompression, the sound track may contain substantial amounts of audio energy at ultra low frequencies. Such low frequencies may not be audible to humans but can be felt, and they add to the experience of watching movies of the science fiction, and action/adventure genres. Even though such audio frequencies are difficult to record, they can be easily synthesized and added to movie sound tracks. This is especially popular in movies that present, for example, explosions, earthquakes or dinosaurs as integral content of the movie.

In the future this problem may become worse since new disc formats such as Blu-Ray® and HD-DVD® will provide wider bandwidth and uncompressed audio.

Conventional loudspeakers (such as subwoofers) designed to handle low frequencies require large acoustic volumes and hence require large amounts floor space; making them inconvenient to locate in a home theater room.

As well, conventionally floor-mounted and wall-mounted loudspeaker transfer significant amounts of acoustic energy or vibrations to the wall and other building structures making low-frequencies audible far beyond the home theater room.

Dudleston et al. (U.S. Patent Application 2003/0123679, filed Dec. 31, 2002) provide an “In-Wall Loudspeaker” designed to mount into a building's interior wall through an opening between two framing studs.

Richie (U.S. Pat. No. 4,296,280, issued Oct. 20, 1981) provides a “Wall Mounted Speaker System” suitable for mounting in the structure of a wall. A mounting assembly adapted for mounting between adjacent wall studs is secured to at least one of the wall studs and receives the speaker enclosure therein.

Combest (U.S. Pat. No. 6,415,886, issued Jul. 9, 2002) provides an apparatus for mounting an audio speaker within a wall such that the apparatus and speaker are attached to and supported by one or more wall studs.

None of the above mentioned loudspeakers and mounting systems mitigate the effects of vibrations transmitted to walls and other building structures nor do they provide means for reproducing low frequencies typically found in LFE channels of popular movies. Clearly, there is a need for an on-wall loudspeaker and mounting apparatus that overcomes the deficiencies of the prior art.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an on-wall loudspeaker and mounting apparatus that mitigates the vibrations transmitted to walls and other building structures, and provides improved means for reproducing low frequencies below a range of conventional loudspeakers.

The present invention provides an on-wall loudspeaker and mounting apparatus that includes an enclosure, a loudspeaker driver mounted in the enclosure, a plurality of brackets each having a substantially equal length and each having a proximal end attachable to a wall, a plurality of arms each having a top end pivotably attached to a respective distal end of each of the brackets and a bottom end pivotably attached to the enclosure, each arm pivotable in a plane of rotation substantially perpendicular to the wall, and each arm having a substantially equal length. A movement of a cone in the driver is parallel to the planes of rotation of the arms when an alternating current signal is applied to the driver.

The length of the arms is chosen to provide a predetermined resonant frequency of the loudspeaker. The predetermined resonant frequency of the loudspeaker is preferably less than a lower cutoff frequency of the driver. Positions of attachment of the bottom ends of the arms to the enclosure and a center of gravity of the loudspeaker are substantially coplanar. The length of the brackets is chosen to be substantially greater than a distance from the distal end of the bracket to a rear surface of the enclosure plus the length of the arms.

Advantageously, the present invention provides an on-wall loudspeaker and mounting apparatus that mitigates the vibrations transmitted to walls and other building structures, and provides improved means for reproducing low frequencies below a range of conventional loudspeakers.

The foregoing and other features of the invention and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various aspects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

InFIG. 1there is shown an on-wall loudspeaker102and mounting apparatus104in accordance with the present invention. The loudspeaker102includes an enclosure106in which there is mounted a loudspeaker driver108having a cone110. A front panel111of the enclosure106is preferably covered with a loudspeaker speaker grill112.

It should be noted that a single active driver108is shown for convenience and clarity only. The loudspeaker102may include multiple active drivers or one or more drones (passive drivers). The enclosure106may also include vents and still be within the scope of the invention. Drones and vents (also known as ports) are well known in the art and are used, in part, to extend a low-frequency range of the loudspeaker102for a given driver108.

A volume of the enclosure106is chosen using conventional design methods well known in the art. Acoustically, the enclosure106may be practically any shape that satisfies the volume requirements. However, for on-wall mounting the enclosure106is preferably shallow and wide enough for the mounting apparatus104(described herein below) to take advantage of conventionally spaced (16 inches) wall studs126. However, the enclosure106and mounting apparatus104may be adapted to take advantage of any type of wall structure that will provide adequate support for the loudspeaker102.

The enclosure106also includes a plurality of pivots114for attaching the loudspeaker102to the mounting apparatus104.

The mounting apparatus104includes a plurality of brackets120that are preferably attachable to vertical tracks122that are secured to a wall124. The brackets120preferably include mounting hooks (not shown) for engaging the tracks122in a similar manner to conventional track and bracket shelving hardware. The wall124preferably includes conventional wood or metal framing studs126and drywall128or similar material fastened to the studs126. It should be noted that the brackets120may be attached directly to the studs126or other structure (not shown) such as a concrete wall or similar structure an still be within the scope of the invention.

The mounting apparatus104also includes a plurality of arms130each pivotably attached to respective brackets120and pivots114attached to the enclosure106. The arms130are preferably made of solid metal, cable or elastomeric loop but may be any material that can support the weight of the loudspeaker.

Referring toFIG. 2there is shown a partial sectional view (A-A) of the enclosure106and mounting apparatus104shown inFIG. 1. The arm130has a top end130apivotably attached to a distal end120aof the bracket120and a bottom end130bpivotably attached to the pivot114. The arm130is pivotable in a plane of rotation202that is substantially perpendicular to the wall124. Each arm130preferably has a substantially equal length (LA)230.

The length of the arms (LA)230is defined as a distance from the center of the pivot point where the top end of the arm130ais pivotably attached to the distal end of the bracket120ato a center of a pivot point where the bottom end of the arm130bis pivotably attached to the pivot114.

A length (LB)220of the brackets120is defined as a distance from a center of the pivot point where the top end of the arm130ais pivotably attached to the distal end120aof the bracket120to the proximal end120bof the bracket120.

In operation, the loudspeaker enclosure102is mounted on the wall124using the mounting apparatus104. An alternating current (AC) electrical signal is applied to terminals (not shown) of the driver108, the cone110vibrates in accordance with the AC signal producing sound. Since, the vibration or movement of the cone110is parallel to the planes of rotation202, the loudspeaker102can swing on the arms130. Thus transfer of vibration from the loudspeaker102to the wall124and hence other building structures (not shown) is substantially reduced.

Preferably, the length of the brackets (LB) is chosen such that:
LB>LA+LC
Where LC232is defined as a distance from the proximal end120aof the bracket120to a rear surface of the enclosure222when the loudspeaker102is at rest. Thus, when the loudspeaker102swings to a maximum amplitude, the enclosure106will not make contact with the track122or wall124. That is, the length of the arms (LA)230is preferably less than a distance LD240from the enclosure106to the wall124. Further aspects of choosing the length of the arms (LA)230are described herein below.

Referring now toFIG. 3, there is shown an isometric view of the loudspeaker102mounted on the wall124using the mounting apparatus104. Even though the loudspeaker102is shown spanning one stud spacing in the wall124, the loudspeaker may span a plurality of stud spacings. Also, the loudspeaker102is shown having a substantially vertical aspect ratio, the loudspeaker may alternatively have a substantially horizontal aspect ratio to accommodate mounting the loudspeaker102in various locations in a room such as below a movie screen or video display (not shown).

Positions of attachment of the bottom ends of the arms130bto the enclosure106(also the positions of the pivots) are chosen to be substantially coplanar with a center of gravity302of the loudspeaker102so that the arms130are substantially vertical when the loudspeaker102is at rest.

FIGS. 4a,4band4c, are graphs410,430,450of sound pressure level (dBSPL)404versus frequency (Hz)402. Idealized frequency responses are shown for clarity only. Those skilled in the art will understand the frequency responses may vary in practice.

FIG. 4ais a graph showing a frequency response410of the loudspeaker102. This frequency response410covers a range from a lower cutoff frequency (FLC1)412to an upper cutoff frequency (FUC1)414. For example, FLC1412is about 20 to 30 Hz and FUC1414is about 80 to 200 Hz for a conventional subwoofer loudspeaker. The frequency response410corresponds to sound produced by the driver108in a conventional manner.FIG. 5ashows a sound radiation pattern502from the driver108.

FIG. 4bis a graph showing a frequency response430of the loudspeaker102. This frequency response430covers a range from a lower cutoff frequency (FLC2)432to an upper cutoff frequency (FUC2)434. This frequency response430corresponds to sound produced by excursion of the loudspeaker102in response to movement of the cone110as described herein above.FIG. 5bshows respective sound radiation patterns504,506for sound produced by movement of the front panel111and rear panel222.

A resonant frequency436(fres) of the loudspeaker is determine by the length (LA)230of the arms130, as described herein below and is preferably chosen to be lower than the lower cutoff frequency412(FLC1).

FIG. 4cis a graph showing a net frequency response450of the loudspeaker102including the frequency responses410,430shown inFIGS. 4aand4b. This frequency response450covers an extended frequency range from FLC2432to FUC1414. Conventional equalization techniques may be used to flatten or emphasize parts this frequency response410as desired.

Advantageously, the length230of the arms is chosen using the well-known formula for a simple pendulum to be approximately:

fres=12⁢⁢π⁢gLAorLA=g(2⁢⁢π⁢⁢fres)2LA≈0.25fres2
where fres(436inFIG. 4b) is the resonant frequency, g is the acceleration of gravity (approximately 9.8 m/s2), and LAis the length230of the arms130(m).

In conventional loudspeakers a maximum acoustic power at low frequencies is typically limited by the maximum allowable linear excursion of the cone110(xmax). xmaxis the maximum linear excursion of a driver or passive radiator measured in one direction from its resting position. It is well known in the art that in conventional loudspeakers including one or more active drivers and one or more drones (or vents) cone excursion of the active driver is substantially reduced at resonant frequencies of drones and vents. In a similar manner, the cone excursion of the active driver108is substantially reduced at the resonant frequency (fres)436of the loudspeaker102on the mounting system104.

Another limitation of conventional loudspeakers is that an area of drivers of conventional loudspeakers (not shown) is inadequate to reproduce low-frequencies (such as shown inFIG. 4b) given a large amount of air movement required. The present invention overcomes this limitation since an area of the front panel111and rear panel222is chosen to be substantially greater than the area of conventional drivers and since the front panel111and rear panel222effectively act as drivers at low-frequencies (as shown inFIG. 5b).

Referring toFIG. 6there is shown side view of another on-wall loudspeaker and mounting apparatus600. This embodiment600is similar to the embodiment shown inFIGS. 1 to 3except that one or more opposite drivers602,604are mounted on an opposite panel (rear panel222) from the loudspeaker driver108that is mounted on the front panel111. Two opposite drivers602,604are shown and are preferably arranged so that they are symmetrically placed about the center of gravity302of the loudspeaker102(FIG. 3). However, as noted above with regard to the loudspeaker driver108, any number of opposite drivers602,604may be used and still be within the scope of the present invention.

A preferred arrangement of the loudspeaker driver108mounted on the front panel111is shown inFIG. 6. However, the loudspeaker driver108may be mounted on the real panel222with the opposite drivers602,604mounted on the front panel111and still be within the scope of the present invention.

The opposite drivers602,604are preferably drones having a lower resonant frequency than the loudspeaker driver108.

Alternatively, active drivers may be used for the opposite drivers602,604. The active drivers are preferably wired so that they have a polarity606that is opposite to a polarity608of the loudspeaker driver108so that a cone of the loudspeaker driver108and cones of the opposite drivers602,604will move in phase when an AC signal is applied to the terminals (not shown) of the drivers108,602,604.

Therefore the present invention provides an on-wall loudspeaker that eliminates floor space requirements of conventional loudspeakers while reducing vibrations transferred to wall and other building structures. Furthermore, the present invention also provides a loudspeaker having extended low-frequency capability especially suited for reproducing sound tracks of movies having significant content on an LFE (low frequency effect) channel.