WO2005022949A1

WO2005022949A1 - Audio communication unit

Info

Publication number: WO2005022949A1
Application number: PCT/EP2004/051951
Authority: WO
Inventors: Daniel Robinson; Gregory Paul Nielan
Original assignee: Sendo International Ltd
Current assignee: Sendo International Ltd
Priority date: 2003-09-03
Filing date: 2004-08-27
Publication date: 2005-03-10
Anticipated expiration: 2006-03-03
Also published as: GB0419293D0; GB2405767A; GB2407934A; GB2407934B; GB0320588D0

Abstract

An audio communication unit comprises at least one acoustic transducer and a housing (202) forming a posterior air volume (304, 306, 308) and/or an anterior air volume (310, 312) associated with the transducer. One or more of the air volumes (304, 306, 308, 310, 312) is provided with a multi-directional sound porting mechanism (204) for directing sound output from the acoustic transducer in substantially different, preferably diametrically opposed, directions on the housing (202) . In this manner, a single polyphonic acoustic transducer is able to simulate stereo sound from an audio communication unit such as a mobile phone and reduce a need for the phone to be spatially located in a particular orientation for listening to by a user of the phone.

Description

AUDIO COMMUNICATION UNIT

Field of the Invention

This invention relates to an audio communication unit and an acoustic arrangement therefor. The invention is applicable to, but not limited to, mobile communication units for reproducing speech, music or any combination thereof.

Background of the Invention

Modern mobile audio communication units are expected to provide high quality sound, have a minimum space volume and footprint, at a low cost. This is especially true of wireless communication units, such as mobile phones, where an improvement in the sound reproduction capabilities of such a device, at a minimum of extra cost, are known to be a key market differentiator between phone manufacturers.

Most wireless communication units are generally designed to operate with only one acoustic transducer or one main transducer or loudspeaker to produce a very uni- directional sound, the level of which is dependent upon the orientation of the device and/or the relative position of the user/listener. The sound from the single speaker is channelled to the outside of the mobile phone through a set of sound holes in the outer plastic housing of the phone. To improve the quality of the audio output from the phone, it is known to use a grommet or gasket to provide routeing of the mono' audio signals to the sound holes. The acoustic quality of these single speaker devices may be improved in so much as the loudspeaker is provided with a suitable acoustic cavity behind it, by designing specific volumes of air at the front and/or back of the speaker, which are partially or fully enclosed. The volume of air contained in the acoustic cavity is chosen with reference to the speaker manufacturer'' s data. The design of this cavity allows the speaker output to be improved for a given frequency band or efficiency requirement, but does not alter the performance or characteristics of the audio communication unit beyond these basic requirements.

It is known that improving the acoustic performance of a wireless communication unit, such as a radio or a mobile phone, can be achieved by incorporating two loudspeakers into the wireless communication unit and driving them with two different input audio signals, via suitable electronic circuits, to produce stereo sound. However, the provision of, in effect, duplicated audio enunciation equipment adds substantially to the cost, size and complexity of the wireless communication unit.

A desired feature of mobile phone users is the ability to play high quality audio music, such as MP3, in addition to supporting normal voice communication. Clearly, for wireless communication units that have previously been designed to support simple, relatively low-quality voice communication, the need to additionally support high quality audio, in addition to voice communication, adds substantially to the cost, size and expense of a mobile phone. Thus, a need exists for an audio communication unit with an improved and inexpensive acoustic design, for example, one that can operate with a single acoustic transducer, wherein the above mentioned disadvantages of current audio communication units may be alleviated.

Statement of Invention

In accordance with a first aspect of the present invention, there is provided an audio communication unit having an acoustic device, as claimed in Claim 1.

In accordance with a second aspect of the present invention, there is provided an acoustic transducer, as claimed in Claim 19.

In accordance with a second aspect of the present invention, there is provided a grommet, as claimed in Claim 20.

Further features of the present invention are as defined in the appended Claims.

In summary, an audio communication unit comprising an acoustic transducer is described whereby one or more of the air volumes associated with an acoustic transducer is provided with a multi-directional sound porting mechanism for directing the sound output from the acoustic transducer to multiple points in the housing of the audio communication unit. In this manner, the provision of multi-directional sound porting from a single acoustic transducer in substantially different (preferably opposed) directions enables audio communication unit to simulate stereo-like sound. In the context of a mobile phone, the provision of multi-directional sound porting from a single acoustic transducer also enables the user- perceived audio quality of the mobile phone to be substantially less reliant on the spatial orientation of the mobile phone in use.

The expression housing^f , in the context of the present invention, encompasses or extends to ^Λcover', ^casing' , ^enclosure' etc. or any part thereof-

Brief Description of the Drawings

Exemplary embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of a wireless audio communication unit adapted in accordance with the preferred embodiment of the present invention;

FIG. 2 illustrates a housing part and grommet arrangement to locate an acoustic transducer, in accordance with the preferred embodiment of the present invention;

FIG.3 illustrates a plan view of a housing part with and without a grommet installed indicating a posterior and an anterior air volume, in accordance with the preferred embodiment of the present invention; and

FIG.4 illustrates a grommet in accordance with the preferred embodiment of the present invention. Description of Preferred Embodiments

The preferred embodiment of the present invention will be described in terms of a mobile telephone. However, it will be appreciated that the invention may be embodied in any other type of audio communication unit that requires or incorporates an acoustic output, for example a portable or mobile radio, a personal digital assistant, a laptop computer with an audio output, etc. It is also envisaged that the present invention is not limited to wireless communication units, as fixed communication units such as business/home telephone devices that connect to the public services telephone network (PSTN) also often include an acoustic transducer for hands free operation, which could benefit from the inventive concepts described herein.

Referring next to FIG. 1, there is shown a block diagram of part of a communication unit 100, adapted to support the inventive concepts of the preferred embodiments of the present invention. The communication unit 100, in the context of the preferred embodiment of the invention is a mobile phone. As such, the communication unit 100 contains an antenna 102 preferably coupled to a duplex filter or antenna switch 104 that provides isolation between receive and transmit chains within the wireless communication unit 100. The receiver chain, as known in the art, includes receiver front-end circuitry 106 (effectively providing reception, filtering and intermediate or base-band frequency conversion) . The front-end circuit is serially coupled to a signal processing function 108. An output from the signal processing function 108 is provided to a suitable output device 110. In accordance with the preferred embodiment of the present invention, the output device is a loudspeaker arrangement for enunciating audio signals, as described in greater detail with respect to FIG. 2, FIG. 3 and FIG. 4.

As known in the art, the receiver chain also includes received signal strength indicator (RSSI) circuitry 112, which in turn is coupled to a controller 114 for maintaining overall communication unit control. The controller 114 is also coupled to the receiver front-end circuitry 106 and the signal processing function 108 (generally realised by a DSP) . The controller 114 may therefore receive bit error rate (BER) or frame error rate (FER) data from recovered information. The controller is also coupled to a memory device 116 that stores operating regimes, such as decoding/encoding functions and the like. A timer 118 is typically coupled to the controller 114 to control the timing of operations (transmission or reception of time-dependent signals) within the communication unit 100.

As regards the transmit chain, this essentially includes an input device 120, such as a microphone and keypad, coupled in series through transmitter/modulation circuitry 122 and a power amplifier 124 to the antenna 102. The transmitter/ modulation circuitry 122 and the power amplifier 124 are operationally responsive to the controller.

In accordance with the preferred embodiment of the present invention, an audio signal is received, demodulated and processed and output in mono-phonic form from processing function 108 to the loudspeaker arrangement 110. In effect, the loudspeaker 110 is an acoustic device with only one acoustic transducer that reproduces sound communicated to the audio communication unit in the form of electrical signals. Advantageously, the loudspeaker arrangement 110 is configured in such a manner to substantially produce a stereo sound-like effect from a mono-phonic input. This improves the audio performance of the phone from the customer's perspective, not least by allowing better audio quality hands-free operation and better reproduction of high quality music.

In a preferred embodiment of the present invention the air volumes anterior and posterior to the acoustic transducer are isolated from each other such that the sound waves generated at the rear of the transducer do not interfere with those propagating from the anterior of the transducer. In this manner, the efficiency and frequency response of the audio communication unit is improved .

Furthermore, the audio communication unit may be advantageously constructed with an internal and an external, or outer, housing thus allowing the cosmetic and functional aspects of the audio communication unit to be kept substantially separate whilst also allowing further acoustic cavities to be introduced to further enhance the frequency response of the audio communication unit.

In a yet further advantageous embodiment, the at least front and rear internal housing parts of the audio communication unit are used as structural and acoustic elements, whereby the acoustic transducer is located mechanically by the housing parts. In such an embodiment, the housing in combination with the transducer produces the posterior and/or anterior air volumes required for optimising the acoustic performance of the audio communication unit.

The introduction of a suitably designed grommet, which itself in combination with the housing parts defines the posterior and/or anterior air volumes, simplifies the design of the housing parts, thereby reducing the mechanical complexity of the parts and their manufacturing costs. The acoustic transducer can thus be located mechanically in the grommet, the grommet/transducer sub assembly then being located between the housing parts to define the required air volumes .

The preferred acoustic arrangement ensures that a particular volume of air is provided in the cavities. This volume of air is dependent upon the dimensions of the loudspeaker. In particular, anterior air volumes are designed to allow a speaker membrane to travel a given amount to create the desired resonance, i.e. if a cavity is too small the speaker membrane travel is limited, whereas if the cavity is too large the air will not be compressed by the speaker membrane creating unwanted noise and vibrations.

In order to ensure excellent acoustic performance the grommet may, in a further advantageous embodiment, be sealed to the inner housing parts such that the air volumes may be isolated from each other and/or from other parts of the housing, thus substantially eliminating unwanted resonances.

The grommet itself is designed with at least two output ports located substantially equidistant from the axis of symmetry of the grommet which extend out to, and through, the inner housing of the phone and are sealed to the inner housing.

Preferably, the grommet is designed such that the acoustic transducer is located substantially centrally within the audio communication unit allowing for equal length output ports which preserve the phase relationship of the sound at the egress points of the at least two output ports of the audio communication unit. In a yet further advantageous embodiment, the grommet is designed such that the acoustic transducer is located off-centre in the audio communication unit providing unequal length output ports and allowing for a more complex phase relationship of the sound at the egress points of the output ports, if so desired. The use of a loudspeaker as the acoustic transducer provides a further beneficial embodiment of the invention, thus allowing the audio communication unit to be constructed from readily available low cost components with well defined design parameters .

The sound produced by the action of the acoustic transducer in the anterior air volume propagates, via the output ports, through the walls of the inner housing, thus preventing any loss of acoustic energy in the body of the audio communication unit and allowing accurate control of the direction of the sound. The grommet itself is preferably manufactured from a from rubber with a high durometer. Thus, it is rigid enough to hold its shape and retain the acoustic transducer component. However, it is also soft enough to compress to form effective sealing at the various junctions with the housing. Such a design facilitates good quality sound reproduction. The inner housing material is very rigid.

A further advantageous embodiment, involves the provision of openings in the outer housing located substantially adjacent to the points at which the output ports exit the inner housing. This allows the grommet to be sealed effectively to the outer_ housing. This second seal provides an effective barrier against ingress of dust and water, while also allowing sound to propagate unhindered out of the audio communication unit.

Thus, an audio communication unit having an acoustic device is provided with a multi-directional sound porting mechanism arranged to direct the sound output of the acoustic transducer to multiple points in the housing. In this manner, air volumes are provided to optimise the performance of the acoustic transducer such that the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

The invention can be better understood by reference to the following description of a preferred embodiment, as illustrated in FIG' s 2 to 4.

Referring now to FIG. 2, more detailed views of the loudspeaker arrangement of the preferred embodiment of the present invention is illustrated. A first view 200 illustrates the loudspeaker arrangement comprising a housing part 202 of the mobile phone with a detachable grommet 204. The grommet 204 is so configured that, when located in the housing part 202, they form an acoustic environment in the mobile phone to reproduce audio signals such as voice or music.

Furthermore, the grommet 204 is configured to provide a location point 206 for an acoustic transducer, in this case a polyphonic loudspeaker (not shown). Although the preferred embodiment of the present invention is described with reference to a loudspeaker-based acoustic transducer, a skilled artisan will appreciate that the inventive concepts herein described can be equally applied to many forms of acoustic transducer such as a piezo-electric or electrostatic device.

The housing part 202 contains cut-out portions 210, 212 to provide an opening and support for an audio porting mechanism 208 of the loudspeaker-based acoustic transducer to access the exterior of the mobile phone. The audio porting mechanism 208 of the grommet 204 is therefore mechanically designed to slot into the housing space to provide an acoustic seal.

A second view 220 of FIG. 2 illustrates the grommet part 204 in situ with the housing part 202 forming the desired acoustic environment. As shown, the audio porting mechanism of the grommet 204 advantageously forms an acoustic seal 214 with the housing part 202.

Referring now to FIG. 3, a plan view 300 of the loudspeaker arrangement of the preferred embodiment of the present invention is illustrated. A first view 302 illustrates the housing part 202 of the mobile phone in isolation, with a second view 320 illustrating the housing part 202 with the detachable grommet 204 in situ.

A loudspeaker, for example, has a defined compliance which in combination with its mechanical housing causes it to operate at a specific efficiency and/or output power and/or frequency bandwidth. These performance values are dependant, among other things, upon the volume of the posterior air cavity that is formed by the housing part 202. The posterior air cavity in FIG. 3 is formed by the two mechanically sealed parts 304, in conjunction with the volume space 308 located on the opposite side of the grommet 204.

Finally, in the preferred embodiment of the present invention, the posterior air cavity in FIG. 3 is also formed from the area 306 under the loudspeaker (when located) in the centre portion of the grommet 304. In such a configuration, the posterior air cavity acts as an air-spring preventing excessive excursions of the loudspeaker cone. This prevents unwanted resonances and noise as well as shapes the frequency response of the loudspeaker.

In FIG. 3, the anterior air volume is formed by two substantially diametrically opposite sides 310, 312 of the grommet 304, which also acts as a resonant cavity and shapes and amplifies the output sound. Although it is sealed to the inner housing, it is by necessity directly open to normal air pressure and thus has a more limited effect. Isolation of the anterior and posterior volumes is necessary to prevent ^λsound leakage' from the front to the back of the loudspeaker which has the effect of reducing the audio output level, quality and clarity of sound.

Referring now to FIG. 4, a more detailed view 400 of the grommet part 204 of the preferred embodiment of the present invention is illustrated. The loudspeaker is sealed to the surface 402 by mechanical pressure exerted by the front and back housing parts of the mobile phone. The inner housing preferably sits on a PCB (not shown) . The PCB is sandwiched between the front and back housings when they are assembled together. When assembled within the mobile phone's housing, a defined air volume (posterior volume) is created behind the speaker and within the inner housing, the spatial parameter of the air volume being optimised for operation with the transducer. The Inner housing can also be sealed to the PCB, if required, to acoustically seal the back volume from the outside world.

Advantageously, sound produced by the single loudspeaker is routed via the two audio porting mechanisms 404, 406 to two output ports 408, 410 adjacent to the outer surface of the audio communication unit. The output ports are preferably sealed to the housing part by applying pressure on the grommet from the front and back housing of the mobile phone. The enunciated audio signals then propagate in free space. Advantageously, the two outputs of the audio communication unit result in a quasi-stereo, bi-directional sound for the audio communication unit's user. Although the preferred embodiment of the present invention is described with reference to two output ports from the loudspeaker-based acoustic transducer, a skilled artisan will appreciate that the inventive concepts herein described can be equally applied to further output ports in different configurations. Thus, it is envisaged that multiple output ports can be used to employ the inventive concepts described herein, for example to aim to simulate a surround-sound perceived effect for the listener. Notably, the multi-directional sound porting mechanism directs sound output from the acoustic transducer in substantially different, and preferably diametrically opposed, directions on the housing, in order to better reproduce stereo sound.

Referring back to FIG. 4, it can be seen that the grommet 204 has two substantially diametrically opposed extrusions 404, 406, each of which has an output port 408, 410 with a baffle 304 for allowing sound out of the mobile phone. Notably, the output port of the grommet 204 comprises, for example, three holes and a surround sealing surface, which seals the speaker grommet to the outer cosmetic housing of the phone.

In accordance with the preferred embodiment of the present invention, the audio porting mechanism comprising these extrusions is substantially equal in length. In this manner, the extrusions provide a constant phase shift at the outer surface of the audio communication unit. In alternative embodiments of the present invention, it is envisaged that it is possible to ^Λtune' the output ports by varying their lengths, in order to provide specific frequency responses and alter the general sound being enunciated from the audio communication unit.

It is further envisaged that a second loudspeaker may also be incorporated into the audio communication unit for creating more complex sounds. For example, it is envisaged that novel sound effects can be generated by carefully managing the audio applied to the first and second speakers by say, mixing or fading audio signals between the speakers . In the context of a mobile communication unit, this feature is advantageous in that the manufacturer is able to add special features to the unit as well as gimmicks such as DJ mixing between two separate tracks of music each from a different speaker.

Alternatively, it would be possible to mix sounds between two separate tracks of music, one from a speaker and one from a headset, etc.

Alternatively, the second loudspeaker may also be incorporated into the audio communication unit for use with speech only, with the speaker/grommet arrangement of the preferred embodiment being used separately for high quality audio and/or music. In such a manner, it would thus be possible, via the second loudspeaker, to alert the user to an incoming telecommunication call while playing MP3 music on the main speaker.

It is within the contemplation of the invention that the provision of an improved audio enunciation arrangement, as described above, can also be used for gaming purposes on mobile phones, in addition to providing a simulated stereo-like sound effect. In this regard, it is envisaged that the phone's games may provide uninterrupted background music, with the primary game sounds provided by the additional speaker over the top of the background music to provide improved gaming interaction.

Thus the present invention provides a number of advantages over current handheld electronic products such as alkmans, mobile phones, MP3 players etc. The inventive concepts described herein find particular applicability when you it is difficult to port sound out of a front of a product towards the end user, due to the architechture of the product. For example, an end-user of a musical product such as a mobile phone that employs the inventive concepts herein described is able to place their mobile phone on a table, or use in their hand, etc., and listen to music. Advantageously, the sound quality produced by the phone is not dependent upon a spatial positioning of the handset.

It will be understood that the audio communication unit with an acoustic transducer as described above aims to provide at least one or more of the following advantages: (i) The bi-directional (or multi-directional) sound porting mechanism enables the same audio/sound to be enunciated from two (or more) sides of the mobile phone using one polyphonic speaker, thereby improving the perceived sound quality as heard by the phone user, (ii) The aforementioned acoustic arrangement provides a fuller, multi-directional surround sound effect which appears to emanate from various locations around the phone, which is particular useful when a mobile phone is playing high quality audio sounds. (iii) The provision of a second speaker enables one simple speaker to be used for low-quality audio, whilst the bi-directional (or multi-directional) sound porting mechanism can be used to support high quality audio output. (iv) The aforementioned acoustic arrangement is configured to provide a dust and water-tight seal, in addition to an acoustic seal from other internal areas of the phone. (v) The aforementioned acoustic arrangement is much more resistant to variable audio quality due to an orientation of the phone, as the same audio is output from two separate ports.

Whilst the specific and preferred implementations of the embodiments of the present invention are described above, it is clear that one skilled in the art could readily apply variations and modifications of such inventive concepts .

Thus, an audio communication unit with an acoustic transducer has been described where the aforementioned disadvantages with prior art arrangements have been substantially alleviated.

Claims

1. An audio communication unit (100) comprises an acoustic transducer and a housing (202) forming a posterior air volume (304, 306, 308) and/or an anterior air volume (310, 312) associated with the transducer, the audio communication unit (100) characterised in that one or more of the air volumes (304, 306, 308, 310, 312) is provided with a multi-directional sound porting mechanism for directing sound output from the acoustic transducer in substantially different, preferably diametrically opposed, directions on the housing (202).

2. The audio communication unit (100) according to Claim 1, further characterised in that the anterior air volume (310, 312) and the posterior air volume (304, 306, and 308) are acoustically isolated from one another.

3. The audio communication unit (100) according to Claim 1 or Claim 2, further characterised in that the anterior .air volume (310, 312) is formed as part of the housing.

4. The audio communication unit (100) according to any preceding Claim, further characterised in that the at least one posterior air volume (304, 306, 308) is formed within a detachable grommet (204) for attaching to the housing (202) .

5. The audio communication unit (100) according to any preceding Claim, further characterised in that the housing is formed from at least a front part and a rear part such that the acoustic transducer is located in the audio communication unit (100) by the front and rear housing parts.

6. The audio communication unit (100) according to any preceding Claim, further characterised by a grommet (204) capable of supporting the acoustic transducer.

7. The audio communication unit (100) according to Claim 6, further characterised in that the acoustic transducer is located in the grommet (204) which itself locates the acoustic transducer off-centre in the audio communication unit (100) .

8. The audio communication unit (100) according to Claim 6 or Claim 7, further characterised in that the grommet (204), in combination with front and/or rear housing parts, defines the posterior air volume (304, 306, 308) and/or anterior air volume (310, 312).

9. The audio communication unit (100) according to any of preceding Claims 6 to 8, further characterised in that the grommet (204) is acoustically sealed, at least in sections (210, 214) to an inner and/or outer portion of the housing (202).

10. The audio communication unit (100) according to any of preceding Claims 6 to 9, characterised in that the grommet (204) has at least two substantially equidistant acoustic output ports (408, 410) extending at least to the housing (202), wherein the output ports (408, 410) are acoustically sealed to the housing (202).

11. The audio communication unit (100) according to Claim 10, further characterised in that the acoustic transducer is located in the grommet (204) in a location substantially equidistant from the at least two acoustic output ports in the audio communication unit (100).

12. The audio communication unit (100) according to Claim 10 or Claim 11, further characterised in that the housing (202) of the audio communication unit (100) comprises an inner housing part and an outer housing part, wherein the at least two output ports (408, 410) extend through openings in the inner housing to the outer housing such that the output ports are acoustically sealed to the outer housing.

13. The audio communication unit (100) according to Claim 11 or Claim 12, further characterised in that the at least two output ports (408, 410) are located on substantially opposite sides of the audio communication unit (100).

14. The audio communication unit (100) according to any of preceding Claims 11 to 13, further characterised in that the location of the at least two output ports (408, 410) is selected to provide a substantially orientation independent acoustic output.

15. The audio communication unit (100) according to any preceding Claim, further characterised by a second acoustic transducer, such that the second acoustic transducer is used substantially for voice communication.

16. The audio communication unit (100) according to Claim 15, wherein the multi-directional sound porting mechanism of a first transducer is used to enunciate music and/or gaming sounds.

17. The audio communication unit (100) according to any preceding Claim, further characterised in that the audio communication unit (100) is a mobile phone.

18. The audio communication unit (100) according to any of the preceding Claims characterised in that the acoustic transducer is a loudspeaker.

19. An acoustic transducer (110) adapted for use in the audio communication unit (100) according to any of the preceding Claims .

20. A grommet (304) adapted to support an acoustic transducer (110) for use in the audio communication unit (100) according to any of preceding Claims 1 to 18.

21. An audio communication unit (100) comprises at least one acoustic transducer and a housing (202) forming at least one posterior air volume (304, 306, 308) and/or at least one anterior air volume (310, 312) associated with the transducer, the audio communication unit (100) characterised in that one or more of the air volumes (304, 306, 308, 310, 312) is provided with a multidirectional sound porting mechanism for directing sound output from the at least one acoustic transducer to multiple points in the housing (202).