Field of the Invention

[0001] This invention relates to an audio device capable of adaptation to a range of different functions.

Background to the Invention

[0002] In EP1435190 we disclosed and claimed a number of audio devices based on a magnetostrictive actuator, each adapted to enable various surfaces to radiate audible sound when the device is secured to the surface or held closely on it. Some of the devices were adapted to receive the audio drive sig- nals wirelessly, while others were provided with a plug connector for a wired connection. One example of such a device was a wireless telephone handset.

[0003] While such devices offer acceptable sound quality for communications purposes, good music reproduction and improved speech intelligibility require a wider frequency response with greater power, and this in turn requires a larger piece of the magnetostrictive material and greater reactive mass. However, increasing the size of the magnetostrictive material and increasing the reactive mass of the device acting through the actuator on the foot both tend to increase the bulk and cost of the device, imposing constraints on the design and use of the device. The present invention seeks to overcome these con- straints.

Summary of the Invention

[0004] According to the invention, there is provided an audio device comprising a casing containing the following components:

a An audiofrequency actuator;

b power supply means; and

c driver means for supplying a driving signal to the actuator; d a foot extending outside the casing beneath the casing so as to be engageable with a surface into which audiofrequency vibrations generated by the actuator can be coupled, whereby the surface radiates sound,

Specification FEONPLOP1618. WOP— 201 0-1 1 -29 characterised in that the foot is located adjacent to one end of the casing, and a support is located on the underside of the casing adjacent to the end thereof opposite to the said one end, whereby the mass of the device has a moment around said support acting through the foot.

[0005] It has been found that mounting the foot in this way enhances the performance of the device by improving the bass response without having to increase the mass of the device.

[0006] Preferably, the device also contains a microphone and a wireless transmitter and receiver, and the driver means comprises a controller connected to each of these components and arranged to supply to the actuator an audiofrequency signal, the controller being programmable to control the operation of the microphone and the wireless transmitter and receiver.

[0007] The power supply means preferably comprises at least one rechargeable battery, and connector means are provided on the casing for con- necting a battery-recharging supply. Signal connector means may also be provided on the casing for connecting an external audio signal to the driver means.

[0008] In a preferred embodiment, the driver means is adapted to separate a stereo signal into separate channels and to supply one channel to the audiofrequency actuator and the other channel to an output for connection to another of said audio devices. For example, the output may be a socket on the casing for connection to said other audio device by wire. Alternatively, the output is via a wireless transmitter to a receiver in said other audio device. While the wireless transmitter could be an optical transmitter, it is suitably a radio transmitter, for example a Bluetooth ^® or Wifi transmitter. The driver means may be adapted to separate the stereo signal in response to detection of the other audio device.

[0009] The audiofrequency actuator is preferably a magnetostrictive actuator, which is preferably arranged to act on the foot through a lever arrangement whereby to magnify the amplitude of the audiofrequency vibrations delivered to the foot. The magnetostrictive actuator is preferably arranged substantially hor- izontally.

Specification FEONPLOP1618. WOP— 201 0-1 1 -29 [0010] The casing may be provided with display means, for example to display information relating to music being played. This may consist of a VLCD displaying a single line of text, for example streaming text. Additional external controls may be provided, for example a keypad or keyboard.

[0011] The audio device of the invention is very compact, but capable of generating high quality sound output from a range of different types of surface. The enclosed body renders the device suitable for use in damp conditions, such as in bathrooms and in the open air.

[0012] The audio device could be used as an audio tester. For example if it played a continuous or pulsed broadband tone it could be used to determine ideal mounting positions on a panel for a panel driver sounder (determine points on panel that will generate high output and low output). In addition, as a tone generator it could also be used to test/tune musical instruments such as a violin, or to non-destructively identify damage to a panel. For example, a rotting wood panel or a panel/tile detached from rest of structure will sound different from a good one.

[0013] The audio device could be used as a language tutor with the addition of memory card, MP3 player and a microphone, the language lessons being recorded on the memory card and played back via the device and responses from the pupil are recorded and played back and compared, perhaps even advising of correct pronunciation.

[0014] The audio device of the invention can be used as a hearing aid. By placing the foot of the device against a person's skull or mastoid bone, sound can be transmitted through the skull to the inner ear. It has been found that even some profoundly deaf people have been able to hear sounds again by this means. The audio device will conveniently be a self-contained device in which a microphone is incorporated, with the driver means driving the actuator with the signal received by the microphone. It is believed that a small version of the device could thus be shared without any hygiene of social implications, as it does not need to contact the inside of a person's ear. This may be important in parts of the world where the cost of equipping each person with hearing difficul-

Specification FEONPLOP1618. WOP— 201 0-1 1 -29 ties with a conventional hearing aid is prohibitive. The device may, for example, be incorporated into a cap, bandanna, head scarf or the like, making it less conspicuous in use, and so increasing acceptance.

[0015] Instead of incorporating a microphone, the device could receive wire- lessly a signal from a central microphone, for example one worn by a teacher in a classroom. Power could be supplied by a solar-powered recharging unit with a simple docking connection.

[0016] A suitable device might provide an output amplitude of less than 10 m with a frequency-range suited to speech, for example 250Hz to 12.5kHz, although frequencies down to about 100Hz might be achievable. The weight would suitably be of the order of 50g to enable it to be worn comfortably for long periods.

[0017] When the audio device is adapted for use as a hearing aid, the audiofrequency actuator in the device is preferably a magnetostrictive actuator. Brief Description of the Drawings

[0018] In the drawings, which illustrate one embodiment of the invention:

Figure 1 is an end elevational view of the device;

Figure 2 is a top plan view;

Figure 3 is an underneath plan view;

Figure 4 is a sectional elevation on line A-A in Figure 2;

Figure 5 is a sectional elevation on line B-B in Figure 2;

Figure 6 is an enlarged longitudinal section through the magnetostrictive actuator in the device; and

Figure 7 is a perspective view from below of the actuator of Figure 6. Detailed Description of the Illustrated Embodiment

[0019] Referring to the drawings, the audio device comprises an outer casing 1 having projecting through the underside thereof a pad or foot 2 adjacent to one end of the device and engaging a flat surface on which the device is placed. The underside also carries a support member 3 adjacent to the oppo- site end of the device, the member having a pair of projections 4 which also en-

Specification FEONPLOP1618. WOP— 201 0-1 1 -29 gage the surface on which the device is placed, so that the device is supported solely on the projections 4 and the foot 2.

[0020] The exterior of the device is provided at one end with a standard USB2 connector 5 (it will be appreciated that other types of connection could be provided), and indicator lights 6 on the top surface together with an operating push-button 7. Within the casing 1 are mounted rechargeable cells 8 which provide the power to operate the device, a double-sided electronic circuit board 9 mounting components controlling the operation of the device, and a magneto- strictive actuator 10, to which the foot 2 is connected.

[0021] Referring particularly to Figures 6 and 7, the magnetostrictive actuator 10 consists of a cast metal body 1 1 rigidly mounted within the outer casing 1 , and a lever 12 hingedly connected to the body 1 1 , the lever 12 having the foot 2 attached thereto. The hinge connection between the body 1 1 and the lever 12 is through a spring steel leaf 13 which is fixed to each component by means of upstanding posts 14 moulded into the components and passing through holes in the leaf, the posts then being peened or crimped to secure to the component. Two posts 14a are provided on the lever, and four posts 14b are provided on the body.

[0022] As may be seen more clearly from Figure 6, a driver unit 15 extends horizontally between the two components 1 1 and 12. The lever 12 has a recess 16 into which one end of the driver unit is received, while the other end is received in a recess 17 in a screw adjuster 18 which is in turn screw-threaded into a bore 19 in the body 1 1 . The driver unit 15 consists of a pair of small magnetostrictive elements 20, mounted in respective plastic bobbins 21 end-to-end with a permanent disc magnet 22 between them. Further permanent disc magnets 23 are located on the free ends of the elements 20, with an overlying ceramic spacer 24 being provided with a protrusion to engage in the respective recess 16 and 17. Driver electromagnetic coils 25 are wound on the bobbin to surround each element 20, the coils being provided by linking wires with a sig- nal from the circuit board 9. A biasing spring 26 extends vertically between the body 1 1 and the lever 12 to provide an initial compressive force to the driver

Specification FEONPLOP1618. WOP— 201 0-1 1 -29 unit, and thus to the magnetostrictive elements 20. The force can be adjusted by means of the screw adjuster 18.

Specification FEONPLOP1618. WOP—201 0-1 1 -29