GB2504723A

GB2504723A - Waveguide housing for a portable device with built-in passive amplification of the loudspeaker

Info

Publication number: GB2504723A
Application number: GB201214135A
Authority: GB
Inventors: Richard Prudence
Original assignee: ENTANGLE Ltd
Current assignee: ENTANGLE Ltd
Priority date: 2012-08-07
Filing date: 2012-08-07
Publication date: 2014-02-12
Also published as: GB201214135D0

Abstract

Housing comprising an acoustic waveguide and an audio coupling for connecting the waveguide to one or more loudspeakers of a portable device. A plurality of waveguides may be used with each coupled to a speaker. Each waveguide may be open-ended, share a contour wall and operate over a different frequency range and/or attenuate predetermined frequencies. Waveguide outlets may be located in at least two different surfaces of the housing. The housing and waveguide may be magnetic or made of multiple mouldable parts that optimise sound distortion and/or amplification. The housing may protect the portable device and the outer surface may comprise a plurality of different materials for grasping. The audio channel inlet/outlet may protrude beyond the dimensions of the mobile device. The waveguide may also form a fluid conduit for a convection and/or fan driven cooling system. The waveguide may bend around device sensors or connectors with protrusions or extrusions to allow for accessory attachment. The cross-sectional area of the waveguide may be an exponential, parabolic, hyperbolic, linear or other growth function from the speaker throat to horn mouth. The waveguide provides passive amplification of the loudspeaker of a portable electronic device such as a mobile phone or tablet.

Description

A Portable Device with Audio Channel

Field of the invention

The present invention relates generally to a portable device with audio amplification provided in the housing or casing of a portable device such as, but not limited to, a mobile phone. The present invention also concerns integration of an audio waveguide in a portable device, and to the protection of the portable device and its internal components.

io Background

Many portable electronic devices have speakers whose output sound level is much lower than could potentially be generated for the speaker's scale.

This is primarily due to an impedance mismatch between the speaker diaphragm and the output medium. This phenomenon causes most of the energy in the acoustic waves to be reflected back into the speaker's housing, dampened and br converted into heat. Other factors that limit the sound level produced by these speakers may include the device's battery size as well as the commercial need to keep such devices reasonably

portable.

An acoustic audio channel, such as a waveguide allows for manipulation of resonant frequencies to achieve amplification and/or attenuation at certain harmonics and fundamental frequencies. The manipulations are achieved by varying the length, the cross-sectional area, and/or material of the acoustic waveguide. Accordingly by changing the dimensions of the acoustic waveguide, one can optimise performance to specific requirements. Such requirements may include altering the produced sound to more closely adhere to the rules of audio perception, thereby improving the perception of larger bass and treble and improving vocal clarity for a greater listening experience.

Acoustic waveguides have been used historically on this basis, primarily to direct and amplify the sound produced within the body of musical instruments. More modern sound systems make use of acoustic waveguides to improve bass tones; however these waveguides tend to be very large, with acoustic channels of several meters in length.

To ensure compact design, the inlet end of the audio channel is reduced in cross-section in order to prevent the outlet of the horn becoming unreasonably large. This is often made to approximate 1/4 the diameter of the speaker diaphragm. Furthermore, a multitude of different audio channels may be coupled with a single loudspeaker by the means of a io resonance chamber.

Furthermore, the entire acoustic waveguide may be folded and twisted in various configurations. This enables the required length of acoustic waveguide to fit within the boundaries of the sound system, as well as add further control to the output sound

Statements of invention

Instead of trying to improve the technologies of the prior art, it is suggested that audio channels such as acoustic waveguides be used in these systems to facilitate improved impedance matching between the speaker's diaphragm and the medium supporting the output acoustic wave. The present invention is therefore a novel means by which the acoustic vibration produced by a speaker of a portable device can be coupled with the output medium by means of an audio channel. This improves the output sound's characteristics.

The present invention therefore provides apparatus adapted for use with a portable device which includes one or more speakers, the apparatus comprising: a housing; an acoustic waveguide system provided in the housing; and an audio coupling for coupling the waveguide system to at least one of the one or more speakers of the portable device.

Further preferred features of the present invention are listed in the accompanying claims.

An embodiment of the present invention describes an acoustic waveguide adapted for integration into a portable housing or protective casing for use with an existing device. Accordingly, the present invention provides io improved impedance matching as a result of coupling the internal speaker of the portable device with the surrounding atmosphere. The acoustic waveguide may be formed as part of the housing assembly of the device, or attached to the portable device as a casing to protect the internal components of the device or the device housing.

The embedded waveguide may be coupled with a plurality of speakers on the portable device and may exit at more than one surface of the portable device. The embedded waveguide also provides amplification of the audio output without the use of additional power or separate supply. The walls that enclose the waveguide may be formed using any part of the portable device. This includes, but is not limited to, the exterior housing of an existing device, as well as the circuit board or internal battery of a portable device. Therefore in this scenario the proposed waveguide structure may only form following assembly of the device as well as the assembly of its component parts. The waveguide may alternatively be constructed separately and coupled with the speaker on the portable device. Coupling with the speaker may be achieved through the use of an elasticated material (such as elasticated rubber), latch or click-fit mechanism. To facilitate direct coupling with the speaker the inlet or throat' of the waveguide may approximate the dimensions of the speaker geometry, thereby preventing sound loss and leakage. The waveguide assembly as part of the portable device may be made of two or more materials, and be constructed to enhance the functionalities relating to wireless communications thereby extending existing antenna structures for improved signal. The waveguide structure may serve as a fluid conduit for a passive (convection) and/or fan driven cooling system.

The contours of the waveguide within the assembly may be folded around axes centred at positions of outward facing sensors, and parallel to the central axis along the length of the device and housing. The waveguide io may be substantially rectangular or rounded, with a cross-sectional area defined by at least two functions for different sections of the waveguide.

The functions which define the change in waveguide cross-section may be defined substantially by an exponential, hyperbolic, linear or other growth function from the speaker inlet to the waveguide mouth. The waveguide assembly may include a plurality of waveguides originating from a multitude of speakers over various locations of the portable device.

The waveguide assembly includes appropriate extrusions that allow for access to user controls such as buttons, flick-switches, outward facing device sensors (not limited to microphones, light sensors and heat sensors), as well as connectors that facilitate the connection to other digital and analogue devices (This includes chargers and audio jacks) Additionally, the outer surface of the invention may be coated in a gripped material, be engraved or shaped to facilitate manual grasping of the device.

Further features of the invention, its nature and various advantages will be highlighted from the accompanying drawings and the following detailed

descriptions of the preferred embodiments.

List of figures Embodiments of the present invention will now be described by way of example only with reference to the following figures: Figure 1 illustrates the dimensioning and design of a waveguide in accordance with the present invention.

Figure 2 is an exploded perspective view of a configuration of a portable device housing assembly having a waveguide in accordance with the present invention.

Figure 3 is an exploded perspective view of an illustrative configuration with a portable device and protective case assembly having a wave guide in accordance with the present invention.

Figure 4 is a top view of the waveguide housing illustrating the embodiment of the wave guide mouth from an exterior side speaker on the portable device.

Figure 5 is a top view of the waveguide housing of figures 2 and 3 illustrating the scenario of the waveguide mouth exiting from multiple planes of the portable device housing and illustrates use of the an Is embedded wave guide in the housing or case of a mobile electronic device for convection cooling of the internal components and casing where a heat source is positioned nearer to waveguide mouth.

Figure 7 illustrates use of an embedded waveguide in the housing or case of a mobile electronic device for convection cooling of the internal components and casing where an audio source is positioned nearer to wave guide mouth.

Figure 8 is an isotropic view illustrating an example configuration of the protective case assembly.

Figure 9 is a side illustration of the bottom of a device and/or case assembly in accordance with the present invention.

Figure 10 is a cross-sectional side view of a waveguide throat with the coupling of the audio speaker on the side of the portable device.

Figure 11 is a cross-sectional side view of a waveguide throat coupling with an audio speaker on the underside of the portable device.

Figure 12 is a top view illustrating an example configuration of multiple wave guides protruding beyond the housing of a larger portable device in accordance with the present invention.

Specific description

-In the context of this document reference herein to portable electronic devices is intended to include, but not be limited to, laptop computers and other small portable computers of the type that are sometimes referred to as ultra-portables. The term portable electronic devices is also intended to encompass smaller devices, io including wrist-watch devices, pendant devices, headphone and earpiece devices and other wearable miniature devices. The term portable electronic devices are additionally intended to encompass portable wireless electronic devices.

-Wireless electronic devices include, but are not limited to, Is handheld wireless devices such as cellular telephones, media players with wireless capabilities, handheld computers (personal digital assistants), remote controllers, global positioning systems (GPS) devices and handheld gaming devices. The wireless electronic device may also be a hybrid device that combines functionality from multiple conventional devices. Examples of hybrid portable devices include smart phone devices and tablets that offer a range of media, gaming and communication capabilities (including email functions, GPS and connections to cellular networks, web browsing and music player functionality). The aforementioned devices are merely illustrative, non-limiting, examples.

-A portable electronic device, such as a handheld electronic device generally has an upper portion and a lower portion. The upper portion may include components such as a display, touch screen and housing frame. The lower portion, which may sometimes be referred to as the housing assembly, may include a housing, printed circuit boards, and electrical components that are mounted to the housing and printed circuit boards.

-For the embodiments described later reference to a "waveguide" is intended as reference to a functional element having the following characteristic features: one or more walls defining an acoustic enclosure with contours that control one or more of the direction, amplitude and frequency response of the sound radiation.

When the waveguide is coupled to an acoustic energy source propagation of an acoustic wave front to the free air at the horn exit io can be controlled. A waveguide by definition may include one or more waveguide source inlets and exits.

-An exemplary waveguide can be characterised by the ratio between the cross-sectional area of the waveguide exit with the waveguide inlet and the length of the waveguide. FIG.1 graphically depicts the features of consideration used to design a waveguide of exponential cross-section. Feature 2 indicates a possible resonance chamber as a coupling aid with an active speaker 1. Feature 3 indicates a possible coupling between active speakers with a large cross-section to a waveguide with an inlet of smaller cross-section 4.

Inclusion of a coupler allows for the consideration of a waveguide inlet of smaller cross-section, thereby offering the possibility of significantly larger amplification for a given length 8, henceforth denoted by L, of the waveguide. The coupler 3 additionally reduces the acoustic impedance and resonances produced by internal reflections and standing waves.

-In reference to FIG.1 the relationship between the cross-sectional area of the inlet, exit and length of the waveguide may be explained mathematically. To aid in explanation, feature 4 will henceforth be referred to as the "throat" and with cross-sectional area S0. Similarly, feature 6 will be referred to as the waveguide "mouth", denoted by cross-sectional area S(x) at length x. In the case of an exponential horn, the flare constant m, over the waveguide length is given by the following expression: -S(x) = SO exp(m x) from x0 and x=L The exponential change in waveguide cross-section is generated symmetrically about a common longitudinal axis 7. The flare constant m of the exponential may be determined by the following relationship: m =!n(S(L)IS(O))/L The associated cut-off frequency for the designed horn may then be determined from the following expression: fc = mcI4*pi -In practise linear waveguides are impractical and may be Is folded to adopt less unreasonable shapes suitable for use in households and on portable devices. The bending of a waveguide causes acoustic distortion that must be rectified by bending the guide in the opposing direction. Bending of the waveguide may be performed around both axes perpendicular to the central axis 7 of the waveguide.

-Using a smooth material for the inner wall surface of the waveguide can reduce the distortion of higherfrequencies, thereby maximising the effective bandwidth of the waveguide. Examples of such materials include metals and metal alloys, plastics such as polycarbonate, silicates including glass, Teflon, ABS plastic, polyurethane and others. The prescribed material may also be biodegradable and/or produced by a number of layers of different materials with known characteristics.

-The structure of the waveguide may be folded to be embedded into the lower portion or housing assembly 20 of a mobile device 21 as shown in FIG.2 to aid in the protection of internal components, to passively amplify and to improve audio quality by controlling generated sound distortion.

-The housing 19 may be formed of any suitable materials including, plastic, wood, glass ceramics, metals, or other suitable materials, or any combination of these materials. Of these materials light-weight low density materials such as polycarbonate, ABS plastic, aluminium and select wood types are preferred due to their known characteristic to reflect sound. The use of these materials may be to increase strength, reduce weight or aid in the enhancement or io improvement of existing device functions and enhance sound quality.

-There may be situations when more pliable and elasticated materials are desired over smooth and rigid structures. Such a circumstance may be used to create a vibrational medium, similar to a speaker Is membrane along the length of the audio channel and/or exterior surface of the case or housing assembly. This vibrational membrane may then be used as an alternative to the motorized vibrators mounting to housing member. In this manner it may serve as a vibrational notification of changing software statuses within the portable device. The membrane may additionally be used to enhance sound production qualities of the case.

-A housing assembly may include printed circuit boards 13, and outward facing connector board 14 to interface the device with other devices, peripherals and other forms of media device. The housing may contain a battery 15, shaped to allow for a flush surface adjacent the internal waveguide 17. Alternatively, an additional support layer 16 may be inserted into the assembly as a flat build platform for components 13-15, and provide an airtight barrier between the internal components and the waveguide to reduce the likelihood of sound leakage.

-The enclosed channel of the waveguide, as part of the housing assembly in FIG.2, may be formed in part by the flat smooth surface of a circuit board or battery within the portable device. In this scenario the audio channel embedded within the device may only be constructed after the full assembly of the device.

-In circumstances when the housing 19 of the device is formed from metal elements, the housing 19 may be used as part of an antenna to support cellular connectivity and wireless communication abilities.

Furthermore, the waveguide 17 may also be made of metal elements to act as an antenna system. Functional elements 19 and 17 may be combined or integrated thereby allowing for manufacture from many or a single part.

-The housing 19 and the waveguide 17 may provide outward facing Is holes to allow for access to sensors on the internal circuit boards, which include cameras, microphone, and other sensors such as light and heat sensors. Connectors, such as charging ports and audio jacks, must also be provided with access through the housing and waveguide material. The housing may be considered part of the internal electronic circuits and devices (PCBs), and used as extended ground plane or capacitive sensor based on the amount of contact with the human hand.

-When combined within the housing of a portable electronic device the waveguide structure in the housing may be used for the conduction of heat and convection over areas where large amounts of heat are generated. An illustration of this combined function is illustrated in the two alternate configurations of FIG. 6 and FIG. 7.

Here a fan, passive heat sink, or heated element is placed as an additional inlet to the waveguide. This inlet may offer the ability to extract air from an additional side of the cavity in the housing structure 42. In this manner any number of configurations of speakers and heat device may be combined in a manner that facilitates a reduced interference with the sounds being produced.

These additional inlets are placed along the contours 39 & 40 of the waveguide shape.

-The upper portion of the device, sometimes referred to as the interface assembly 12, may be comprised of a protective element 9, screen 10 and user controls 11. These interfaces allow for the control of the hardware and software of the device.

-If a waveguide is used as part of the housing for a portable io electronic device in accordance to the device assembly 21, FIG.4 illustrates how support and rigidity may be provided nearer the waveguide cavity at the exit of the waveguide. Here supports 36 may contain screw-holes to fix the internal components of the device to the housing frame. Furthermore fixtures 34 may be placed in Is positions of high density in order to ensure suitable stability. Screw or clipping fixtures 35 may be positioned along the contours of the waveguide as part of the waveguide design, and design of the internal components of the device.

-The waveguide may be attached to an existing portable device 22 to form part of an outer protective case assembly 33. This assembly of illustrative parts may be combined in any configuration to allow for the ease of manufacture or reduce material costs.

-Components pertained to the design of the desired dual-purpose waveguide case are illustrated in FIG.3. The depicted clipping mechanism 24 by which the case assembly is fixed to the device housing may surround the portable electronic device 22, and clip on through the means of elastic tensioning or clipping bezel that covers the interface assembly 12 of the device. The exemplary portable device may pertain to the description of device 21, thereby further extending the functionality of the internal waveguide of the housing.

-In the scenario that the outward facing speaker of the device is positioned on the side of the device, part 23 operates to redirect the sound under the device into the waveguide case 28. This part may be combined with the waveguide for the purpose of reducing parts and ensuring ideal coupling between the active device speaker and the waveguide case.

-In a similar manner to the housing assembly of the portable device in FIG. 2, the enclosed channel of the waveguide as part of a protective case assembly may only be completely enclosed upon the attachment of the portable device. In this scenario, the more than one surface of the portable device may be used to enclose the channel and produce the audio channel. Alternatively, the waveguide may be created separately and then attached to the portable device. FIG.2 and FIG.3 also display the use of an is additional part 16 or 26 which may be used as an internal barrier to more effectively enclose the audio channel and prevent sound leakage. These parts are desired when the underside surface of the portable of device is rough or has textured engravings. Internally, part 16 may be used as a means to isolate active components from the passive design of the waveguide.

-A configuration enabling coupling with a speaker on the side of the portable device 22 or 21 is shown in FIG.1 0. The emergent section 23 of the clipping mechanism 24 couples the audio source or speaker outlet 4 of the device housing with the waveguide inlet 30 by the means of a bending centred about an axis perpendicular to the surface of the interface housing and the direction of the sound radiated from the audio source. Along the radius of curvature of the audio channel through the bend, the cross-sectional area of the waveguide may narrow to approximate the geometry of the speaker outlet. This aims to prevent sound leakage/loss, thereby improving -14-coupling which aids in optirnising amplification and reducing high frequency distortions. This case is also true of the alternative scenario illustrated in FIG. 11.

-The speaker coupler outlet 44 must be at least equal dimensions to the dimensions of the speaker outlet in order to reduce distortions and aliasing of the produced sound. The emergent output of the coupler must be equal to the dimensions of the waveguide inlet 30 to prevent sound leakage and high frequency distortion.

-Part 28, depicted by FIG.9 of the case assembly may provide io extrusions 46, 45 of adequate dimensions to allow for the access of device connectors, buttons and switches constitution user controls, and outward facing sensors such as noise cancelation microphones, light sensors and others.

-In the scenario that the audio output of the portable electronic device is is positioned on the underside of the device 22, FIG.1 I illustrates the alternative arrangement required to couple the acoustic waveguide within the case assembly. Furthermore, in the event that the underside of the device may be suitable for the coupling of the device with the waveguide directly, the optional part 26 of the assembly may be utilised to provide a smooth flat surface for the underside of the device, thereby improving the coupling and prevent sound leakage.

-The waveguide exit may be covered by the means of a grill or cover 32 to add further rigidity to the case assembly 33 or the housing assembly 21. This cover may be constructed of a different material to that of the housing exterior and embedded waveguide. The cover 32 may have extrusions resembling a grill as in FIG.8, vertical or horizontal slits, extrusions resembling a recognisable word or branding symbol.

-In the case of larger portable devices multiple waveguides may be embedded into the device housing assembly or case assembly. An illustration of this is given in FIG.12 where two waveguides with different cut-off frequencies are provided to enhance a different ranges of the audio output, such as base and treble. The audio input to the waveguide inlet may originate from the same audio output.

Using a resonance chamber such as 2 the power of the audio output may allocated proportionally to the waveguide inlets for any number of waveguides and configurations. Within the resonance chamber multiple speakers I may be present, thereby offering stereo sound from a single outlet. Multiple waveguides may originate from io different audio outputs on the device and later combine to produce a single waveguide exit. In the scenario of multiple waveguides the contour walls of the first waveguide may serve as the contour wall of others 52. This optional acoustic barrier 52 allows two isolated waveguides to be produced that originate at a resonance chamber is 2. For the convenience of manufacture and reduced weight this may also be removed.

-FIG. 12 additionally illustrates the possibility of the waveguide assembly wherein an inlet and/or an outlet of the audio channel protrude beyond the dimensions of the pertained mobile device 51.

This outlet may then be covered by a grill or cover 32.

In the foregoing it should be understood that: a) the word "comprising" does not exclude other elements or acts that those listed in the given claim; b) the word "a" or "an" preceding an element does not exclude the presence of plurality of such elements; c) any reference signs in the claims do not limit their scope d) several "means" may be represented by the same item or hardware or software implemented structure or function; e) any of the disclosed elements may be comprised of hardware portions (e.g. including discrete and integrated electronic circuitry), software portions (e.g. computer programming), and any combination thereof; f) hardware portions may be comprised of one or both analogue and digital portions; g) any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise; no specific sequence of acts or steps is intended to be required unless specifically indicated.

Claims

Claims 1. Apparatus adapted for use with a portable device which includes one or more speakers, the apparatus comprising: a housing; an acoustic waveguide system provided in the housing; and an audio coupling for coupling the waveguide system to at least one of the one or more speakers of the portable device.
2. The apparatus of claim 1 wherein the waveguide system io comprises a plurality of waveguides and the audio coupling is adapted to individually couple each of the plurality of waveguides to at least one of the one or more speakers.
3. The apparatus of claim 2 wherein each one of the plurality of waveguides is designed to operate over a different frequency Is range and/or attenuate certain frequencies selected for attenuation.
4. The apparatus of claim 2 or claim 3 wherein the plurality of waveguides have outlets in at least two different surfaces of the housing.
5. The apparatus of claim 2 wherein the contours of one waveguide wall form part of the contour walls of another waveguide
6. The apparatus of any one of the preceding claims wherein, the housing and waveguide are made of multiple mouldable parts.
7. The apparatus of any one of the preceding claims wherein, the material of the housing is selected to prioritise desired effects on sound distortion and/or amplification.
8. The apparatus of any one of the preceding claims wherein the waveguide has an open end not restricted to the edge or surface of the housing.
9. The apparatus of any one of the preceding claims wherein, the housing is adapted to provide protection to the mobile device.
10. The apparatus of any one of the preceding claims wherein the outer surface of the housing comprises two or more different materials.
11. The apparatus of claim 9 wherein the outer surface of the housing is adapted to facilitate manual grasping.
12. The apparatus of claim 10 wherein the outer surface of the housing includes a gripping material and/or is engraved.
13. The apparatus of any one of the preceding claims wherein an inlet and/or an outlet of the audio channel protrudes beyond the dimensions of the pertained mobile device.
14. The apparatus of any one of the preceding claims wherein the waveguide additionally serves as a fluid conduit for a passive (convection) and/or fan driven cooling system.
15. The apparatus of any one of the preceding claims, wherein the waveguide comprises: a plurality of sub-sections that bend around axes centred at positions of outward facing device sensors and peripheral attachment connections.14. The apparatus of claim 13 wherein centre points for further bends in a single waveguide structure are positioned parallel to the central axis along the length of the device and housing.15. The apparatus of any one of the preceding claims wherein the housing and the waveguide consists of a unitary moulded portion or singular engraving.
16. The apparatus of any one of the preceding claims wherein the exit of the waveguide is provided in a plane of the housing or is provided at a corner of the housing.
17. The apparatus of any one of the preceding claims wherein the waveguide is substantially rectangular or rounded.
18. The apparatus of claim 17 wherein the cross-sectional area of the waveguide is defined substantially by an exponential, parabolic, hyperbolic, linear or other growth function from the speaker inlet to the waveguide mouth.
19. The apparatus of claim 18 wherein at least two different functions substantially define the change in cross-sectional area of the waveguide each for a different section of the waveguide.
20. The apparatus of any one of the preceding claims wherein the housing and the waveguide may be made of a magnetic material io or be magnetised.
21. The apparatus of any one of the preceding claims wherein one or more walls of the enclosed channel constitutes a circuit board or part of portable device housing.
22. The apparatus of claim 21 wherein the audio channel is only enclosed upon the attachment of the portable device.
23. The apparatus of any one of the preceding claims wherein a waveguide is coupled to a speaker by narrowing to approximate speaker geometry.
24. The apparatus of any one of the preceding claims where the waveguide may be constructed using a material capable of spatial transmission of vibration: that replaces the need for a motorised vibrator mounted to the housing member.allows sound to be generated from the outer surface of the device housing or casing.
25. The apparatus of claim 1 wherein the housing or protective casing may be curved or provide angled planes that may be appropriate for supporting the device on a flat surface.
26. The apparatus of any one of the preceding claims where additional protrusions or extrusions or magnetic contact allow for the attachment of other accessories to the described invention.-20 -
27. A mobile device including apparatus in accordance with any one of claims ito 26.