Patent Description:
This description relates generally to acoustic speakers, and more specifically, to systems and methods for cooling a printed circuit board (PCB) of a portable powered public address (PA) speaker sound system.

The patent document <CIT> describes an active speaker.

The patent document <CIT> describes a fan cooling of active speaker.

The patent document <CIT> describes an electronics/heat sink housing for a powered speaker.

In accordance with one aspect, the invention proposes a loudspeaker assembly according to claim <NUM>.

In accordance with another aspect, the invention proposes a method for cooling a loudspeaker assembly according to claim <NUM>.

Aspects may include one or more of the following features.

The firebox may surround the heat-generating components of the circuit board and may provide for the convection flow path in the acoustic volume over the heat-generating components of the circuit board.

The vents of the firebox may surround a surface of the circuit board and draw air from the convection path in the acoustic volume to cool the heat-generating components.

The heat sink may extend from the circuit board in a direction away from the acoustic volume for providing the conduction flow path through the circuit board.

The heat-generating components of the circuit board may include a first set of electronic components on one side of the circuit board facing the acoustic volume that is cooled by both the convection and conduction flow paths, and may further include a second set of electronic components on an opposite side of the circuit board as the first set of electronic components that is cooled by the conduction flow path.

The above and further advantages of examples of the present inventive concepts may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of features and implementations.

Public address (PA) speaker systems are well-known for amplifying the reproduction of sound to be heard by a group of people. However, much of the power delivered to a loudspeaker for operation is turned into heat, and addition to heat-generating components such as the power supply, voice coil, motor magnet, battery, resistor capacitor (RC) circuits, and so on, which must be removed to prevent thermal damage to the contents of the loudspeaker, especially its electronic components, and provide a negative impact on its performance.

For example, a powered speaker typically includes a power supply, amplifier and other control electronics. The power supply converts AC to DC to power the amplifier which increases the gain of the audio input signal. In doing so, the circuitry of the control electronics experience efficiency loss resulting in heat dissipation. The heat must be removed from the circuits to prevent them from experiencing thermal breakdown.

In brief overview, examples of the inventive concepts address the foregoing issues faced by conventional powered speakers by configuring the speaker to include both thermal conduction to an aluminum heat sink and the formation of convection cooling paths for moving air inside the acoustic volume. For example, when the speaker is turned on and no audio is playing the heat will escape through firebox vents into the cooler acoustic volume by natural convection. When the powered speaker is playing audio the woofer will move the air, therefore accelerating the heat removal by forced convection.

Referring to <FIG>, a portable powered public PA loudspeaker system assembly <NUM> comprises a circuit board <NUM> such as a printed circuit board (PCB) or the like populated with heat-producing electronic components that produce heat. The enclosure <NUM> (also referred to as a housing or cabinet) may include but not be limited to a top portion, a base, and side surfaces that collectively form an interior in which the circuit board <NUM> as well as one or more acoustic drivers <NUM>, or speakers, and other well-known heat-producing components such as a power supply, battery amplifier electronics, and so on are positioned. In addition, the interior of the enclosure <NUM> provides a sufficient acoustic volume for allowing an audio-producing operation to be performed by the acoustic drivers <NUM>.

The circuit board <NUM> is constructed and arranged so that some heat-generating electronic components 91A such as a resistor capacitor (RC) circuit, primary transformer, and power transistor such as a field effect transistor (FET), and/or other components providing high heat generation are positioned at an acoustic volume side of the circuit board <NUM> and face the acoustic driver <NUM> in the acoustic volume <NUM>, i.e., positioned in the acoustic volume of the enclosure <NUM>. These components are placed near the air flow generated by the transducers for maximum cooling. Other electronic components 91B producing lesser amounts of heat and a heatsink <NUM> are on the opposite side of the circuit board <NUM>, i.e. external to the acoustic volume <NUM> of the enclosure <NUM>.

In addition to providing electronic components 91A, B (generally, <NUM>) for the loudspeaker system <NUM>, the circuit board <NUM>, in connection with a firebox <NUM>, may also provide a barrier. In particular, air inside the acoustic volume <NUM> must be sealed except for the port audio path. Vents <NUM> are provided in the firebox <NUM> that allow air to cool the electronics <NUM> on the circuit board <NUM> but this air must not leak out to the exterior otherwise it will produce an unwanted sound. The circuit board <NUM> acts as a barrier to prevent such air leakage. The firebox <NUM> may include a set of stiffening ribs to strengthen the firebox and stop any vibrations.

In doing so, the circuit board <NUM> may be along both a convection cooling path inside the acoustic volume <NUM>, i.e., for cooling the interior of the loudspeaker system assembly <NUM>, and also along a conduction heat flow path to the heat sink <NUM> collocated with second electronic components 91B extending from the second side of the circuit board <NUM>.

The firebox <NUM> covers an opening of the enclosure <NUM>, and surrounds the circuit board <NUM> at the opening to the enclosure <NUM>, or more specifically, a top surface of the circuit board <NUM> including heat generating components exposed to the acoustic volume <NUM>, to separate the acoustic volume <NUM> from the external environment. The firebox <NUM> is required by government safety regulations, for example, UL approval, in the event of a fire caused by an electronics short circuit. The firebox <NUM> prevents any such fire to be contained from spreading and catch flammable materials on fire. The firebox <NUM> may be formed of plastic or other composite material. The material used to form the firebox <NUM> may be a thermoplastic alloy, for example, including polycarbonate and acrylonitrile-butadiene-styrene (PC/ABS) to provide flame retardancy, which has a UL94-V0 rating or related rating required by safety standards to prevent the plastic from igniting/burning outside a predetermined set of safety requirements.

The firebox <NUM> includes a plurality of vents <NUM> positioned between the acoustic volume <NUM> of the enclosure <NUM> and the circuit board <NUM> to provide a convection cooling path from the acoustic driver and acoustic port <NUM> to the circuit board <NUM>, and more specifically, to direct cooling air at the electronic components of the circuit board <NUM>. For example, the vents <NUM> may be positioned directly over some or all of the electronic components 91A on the side of the circuit board <NUM> facing the vents <NUM> inside the enclosure <NUM>. The periphery of the firebox <NUM> provides a seal about the opening of the enclosure <NUM> so that air in the acoustic volume <NUM>-will not leak.

Also, as shown in <FIG>, a grille, screen, or panel <NUM> may cover a side surface of the enclosure <NUM>, and be positioned over the circuit board <NUM>. The panel <NUM> may receive a set of control elements from the circuit board <NUM> such as volume, tuning, reverb, bass, and/or treble knobs, power source connectors, input connectors, on/off switches, microphone/line switches, instrument jacks, stereo inputs, auxiliary inputs, and so on.

Accordingly, in some examples, a system is provided for cooling an electroacoustic device such as the loudspeaker system assembly <NUM> of <FIG>. As shown in <FIG>, the system includes but not limited to the circuit board <NUM> as well as enclosure acoustic ports <NUM>, acoustic volume <NUM>, firebox <NUM>, heat sink <NUM>, and air vents <NUM> for performing a combination of conduction heat flow and convection cooling, for example, natural convection or forced convection.

For example, as shown in <FIG>, a natural convection flow path is formed by the acoustic ports <NUM> receiving a natural flow of air and circulating the air through the internal volume <NUM>. Also, as shown in <FIG>, the air vents <NUM> of the firebox <NUM> may be located over particular heat-producing electronic components 91A, such as an RC circuit, a transformer, and so on, so that during convection cooling the air flows over and about the electronic components 91A on the side of the circuit board <NUM> inside the enclosure <NUM>. Here, the temperature inside the enclosure <NUM> can be reduced by natural convection cooling by the air vents <NUM> in the enclosure <NUM> and ports <NUM>. As previously described, the circuit board <NUM> may serve as a barrier, so that the firebox <NUM> and at least a portion of the circuit board <NUM> separate the internal acoustic chamber <NUM> from the external environment. In doing so, heat inside the acoustic volume <NUM> can escape only from the air ports <NUM>. Thus, heat is removed from the card cage to an ambient environment, while the air ports <NUM> may also draw cooler air into the enclosure <NUM> from an environment external to the system, and the firebox vents <NUM> allow the cooler air in the acoustic volume <NUM> to cool the electronics <NUM> on the circuit board <NUM>.

In other approaches, heat generated by the electronic components <NUM> on the circuit board <NUM> can also be at least partially removed by conductive cooling, i.e., dissipation or removal of heat from the circuit board <NUM> via the heat sink <NUM>, which conducts heat away from the electronic components <NUM> on the circuit board <NUM> for transfer to the ambient environment.

Accordingly, heat that is generated inside the enclosure <NUM> can be removed by one or more conduction cooling paths and convection cooling paths (shown by arrows in <FIG>) formed between the heat-generating components in the enclosure <NUM> and an ambient environment.

<FIG> is a flow diagram of a method <NUM> for cooling a powered speaker, in accordance with some examples. The method <NUM> may be performed at the portable powered public PA loudspeaker system assembly <NUM> of <FIG>.

At block <NUM>, the enclosure <NUM> is sealed by positioning the firebox <NUM> at its opening.

At block <NUM>, the circuit board <NUM> is sealed inside the firebox <NUM>.

At block <NUM>, during operation of the assembly <NUM>, a convection cooling path is formed in the acoustic volume <NUM>, and directed in a manner established by the presence of the firebox <NUM> and circuit board <NUM>.

At block <NUM>, a conduction heat flow path is formed from the electronic components <NUM> on the circuit board <NUM> to a heat sink extending from the circuit board <NUM> in a direction away from the acoustic volume <NUM>.

Claim 1:
A loudspeaker assembly, comprising:
an enclosure (<NUM>) having a first end and a second end, the first end including an opening and the enclosure having an acoustic port (<NUM>);
an acoustic driver (<NUM>) at the second end of the enclosure (<NUM>);
an acoustic volume (<NUM>) between the first end and the second end of the enclosure (<NUM>);
a circuit board (<NUM>) at the first end of the enclosure (<NUM>);
a firebox (<NUM>) covering the opening at the first end of the enclosure (<NUM>), the firebox (<NUM>) providing a natural or forced convection flow path in the acoustic volume (<NUM>) over heat-generating components of the circuit board (<NUM>) and surrounding the circuit board (<NUM>) at the opening to the enclosure (<NUM>); and
a heat sink (<NUM>) extending from the circuit board (<NUM>) in a direction away from the acoustic volume (<NUM>) for providing a conduction flow path through the circuit board (<NUM>),
wherein:
the firebox (<NUM>) includes a plurality of vents (<NUM>) positioned between the acoustic volume (<NUM>) of the enclosure (<NUM>) and the circuit board (<NUM>) to provide said convection flow path from the acoustic driver and the acoustic port (<NUM>) to the circuit board (<NUM>);
the circuit board (<NUM>) is constructed and arranged so that some heat generating electronic components (91A) providing high heat generation are positioned at an acoustic volume side of the circuit board (<NUM>), in the acoustic volume (<NUM>) of the enclosure (<NUM>) and face the acoustic driver (<NUM>) in the acoustic volume (<NUM>); and
other electronic components (91B) producing lesser amounts of heat and the heat sink (<NUM>) are on the opposite side of the circuit board (<NUM>) external to the acoustic volume (<NUM>) of the enclosure (<NUM>).