GB2365249A

GB2365249A - Mobile phone headset with optical link

Info

Publication number: GB2365249A
Application number: GB0017450A
Authority: GB
Inventors: Michael David Spencer
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-07-18
Filing date: 2000-07-18
Publication date: 2002-02-13
Anticipated expiration: 2020-07-18
Also published as: GB0017450D0; GB2365249B

Abstract

A mobile phone headset comprising, in series, a terminal for electrical connection to an audio output 2 of a mobile phone 3, a signal-carrying means, and a loudspeaker 4, said loudspeaker being responsive to an electrical signal initially generated by said mobile phone and outputted from said audio output, characterised in that said signal-carrying means comprises a linkage in which said electrical signal is converted to a light signal, said light signal then being transmitted though a non-electrically-conducting medium and then converted back into an electrical signal to which said loudspeaker responds, said linkage thereby electrically isolating said loudspeaker from said mobile phone and preventing radio frequency energy from passing from said mobile phone to said loudspeaker.

Description

<Desc/Clms Page number 1> MOBILE PHONE HEADSET This invention relates to a mobile phone headset, of the "hands-free" type which allows the user to engage in a normal two way conversation on a mobile telephone, without having to hold it to one's head.

The design of the headset that is currently in popular use utilises an electrical cable to directly connect the audio output of the phone to an small external loudspeaker, which is placed at the external auditory meatus (the outer opening of the ear canal), and another electrical cable to directly connect the audio input of the phone to a small microphone, which tends to be placed close to the mouth - say clipped to a lapel. Such headsets have the obvious benefit of freeing one's hands for other purposes.

There have been publicised concerns regarding ways in which mobile phones may impact on human tissues nearby. It has been shown that a mobile phone in use will cause nearby skin to increase slightly in temperature (in the same way as a microwave emitter will increase the temperature of food). Furthermore, it is a well established theory in medicine that electromagnetic radiation (including x-rays, light and radio waves) has the potential to confer on normal human cells the ability to develop into cancerous growths.

Whilst intuition may suggest that the hands-free headsets described above would have the benefit of distancing one's head from these potentially deleterious influences, they suffer from the disadvantage that the means used to provide this separation is a direct electrical cable connection - and theoretically any cable attached to a radio transmitter will have the effect of acting as an antenna, transmitting the radiation. In this example the radiation would be carried directly to the ear canal - thus bypassing the intended separation from the body.

An object of this invention is to provide a hands-free headset in which the electrical connection between the telephone and the speaker is disrupted (and thus isolated to transfer of radio frequency energy) by a linkage in which the electrical signal is converted to fight, which is then converted back to an electrical signal by a photo-diode in a separate circuit, which then drives the loudspeaker.

Accordingly, this invention provides for a connection from the audio output of the telephone to an analogue-to-digital converter, the output of which is connected to a light emitter. The output of the emitter is directed to a light receiver, the electrical output of which is connected to a digital-to-analogue converter, the output of which is connected to a loudspeaker.

Preferably this invention includes a fibre-optic cable, which directly links the light emitter to the light receiver. As fibre-optic cables are constructed of materials that do not conduct radio waves (typically glass and a plastic material) this would provide genuine separation of the radio emissions from the body. :1n acceptable alternative however (due say to space limiting constraints) is for the provision of an optical-isolator integrated-circuit chip (an "opto-isolator"), within which a light emitter is in direct and close proximity to the light receiver.

Preferably the invention provides for a similar optical linkage in the information flow from the microphone to the audio input of the telephone. Accordingly it provides for a connection from the microphone to an analogue-to-digital converter, the output of which is connected to a light emitter. The output of the emitter is directed to a light receiver, the electrical output of which is connected to a digital-to-analogue converter, the output of which is connected to the audio input of the telephone. However, due to the possibility of using a microphone at some distance from the head - such as on a tabletop - an acceptable variation of the invention would provide for a direct electrical connection between the microphone and the telephone audio input, whilst maintaining the optical linkage in the line to the speaker- - which unavoidably is used directly next to the head.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing, Figure 1, which shows an overview of the design of the headset.

As shown in Figure 1, a length of fibre-optic cable (1) is provided in the connection between the audio output (2) of the mobile telephone (3) and the loudspeaker (4). To facilitate the transfer of information, the audio output initially passes through an analogue-to-digital converter module (5) and then to a fibre-optic emitter (6). The light emitted passes along the fibre-optic cable (1) to a fibre-optic receiver (7), which is in turn connected to a digital-to-analogue converter module (8), the output of which, is connected to the loudspeaker (4).

A second fibre-optic cable (9) is provided in the connection between the microphone (10) and the audio input (11) of the mobile phone. The microphone (10) is connected to an analogue-to-digital converter module (12), the output of which is connected to a fibre-optic emitter (13). The light emitted passes along the fibre-optic cable (9) to a fibre-optic receiver (14), which is in turn connected to a digital-to-analogue converter module (15), the output of which is connected to the audio input (11) of the telephone. An alternative embodiment of the invention will now be described with reference to the accompanying drawing, Figure 2.

As shown in Figure 2, the audio output (2) of the mobile telephone (3) is connected to an analogue-to-digital converter module (5) the output of which is connected to a fibre- optic emitter (6). The light emitted passes along the fibre-optic cable (1) to a fibre- optic receiver (7), which is in turn connected to a digital-to-analogue converter module (8), the output of which is connected to the loudspeaker (4).

The microphone (10) is directly connected to the audio input (11) of the telephone by means of an electric cable (16).

An third embodiment of the invention will now be described with reference to the accompanying drawing, Figure 3.

As shown in Figure 3, the audio output (2) of the mobile telephone (3) is connected to an analogue-to-digital converter module (5) the output of which is connected to the light-einitting component (17) of an opto-isolator (18). The light-einitting component

is in direct proxxhnity to the light-receiving component (19), the output of which is connected to a digital-to-analogue converter module (8), the output of which is connected to the loudspeaker (4).

The microphone (10) is connected to an analogue-to-digital converter module (12), the output of which is connected to the light-emitting component (20) of an opto-isolator (21). The light-emitting component is in direct proximity to the light-receiving component (22), the output of which is connected to a digital-to-analogue converter module (IS), the output of which is connected to the audio input (I I) of the telephone. To summarise, this invention provides for a novel alternative to the direct electrical connection in the cui-rently available headset apparatus, in order to isolate the user from the transfer of potentially harmful radio frequency energy. This is achieved by an isolating stage where the information is temporarily converted to, transmitted as, and converted back from the medium of light.

Claims

CLAIMS 1. A mobile phone headset comprising, in series, a terminal for electrical connection to an audio output of a mobile phone, a signal-carrying means, and a loudspeaker, said loudspeaker being responsive to an electrical signal initially generated by said mobile phone and outputted from said audio output, characterised in that said signal-carrying means comprises a linkage in which said electrical signal is converted to a light signal, said light signal then being transmitted through a non-electrically-conducting medium and then converted back into an electrical signal to which said loudspeaker responds, said linkage thereby electrically isolating said loudspeaker from said mobile phone and preventing radio frequency energy from passing from said mobile phone to said loudspeaker.
2. A mobile phone headset comprising, in series, a terminal for electrical connection to an audio input of a mobile phone, a signal-carrying means, and a microphone, said audio input being receptive to an electrical signal initially generated by said microphone, characterised in that said signal-carrying means comprises a linkage in which said electrical signal is converted to a light signal, said light signal then being transmitted through a non-electrically- conducting medium and then converted back into an electrical signal received by said audio input of said mobile phone, said linkage thereby electrically isolating said microphone from said mobile phone and preventing radio frequency energy from passing from said mobile phone to said microphone.
3. A connector for use with a mobile phone, said connector comprising, in series, a terminal for electrical connection to an audio output of a mobile phone, a signal-carrying means, and a terminal for electrical connection to a loudspeaker, said loudspeaker being responsive to an electrical signal initially generated by said mobile phone and outputted from said audio output, characterised in that said signal-carrying means comprises a linkage in which said electrical signal is converted to a light signal, said light signal then being transmitted through a non-electrically-conducting medium and then converted back into an electrical signal to which said loudspeaker responds, said linkage thereby electrically isolating said loudspeaker from said mobile phone and preventing radio frequency energy from passing from said mobile phone to said loudspeaker.
4. A connector for use with a mobile phone, said connector comprising, in series, a terminal for electrical connection to an audio input of a mobile phone, a signal-carrying means, and a terminal for electrical connection to a microphone, said audio input being receptive to an electrical signal initially generated by said microphone, characterised in that said signal-carrying means comprises a linkage in which said electrical signal is converted to a light signal, said light signal then being transmitted through a non-electrically- conducting medium and then converted back into an electrical signal received by said audio input of said mobile phone, said linkage thereby electrically isolating said microphone from said mobile phone and preventing radio frequency energy from passing from said mobile phone to said microphone.

<Desc/Clms Page number 5>
5. A headset as claimed in Claim 1 or Claim 2 wherein the linkage comprises a light emitting component, a non-electrically-conducting medium, and a light receiving component, said linkage being such as to prevent radio frequency energy from passing from the mobile phone to the loudspeaker or microphone.
6. A headset as claimed in Claim 5 wherein the non-electrically-conducting medium comprises a length of optic fibre.
7. A headset as claimed in Claim 5 wherein the light receiving component comprises a photo-diode.
8. A headset as claimed in Claim 5 wherein the linkage comprises an opto- isolator device in which a light emitting component is in direct proximity to a light receiving component.
9. A headset as claimed in Claim 8 wherein the light receiving component in the opto-isolator device comprises a photo-diode.
10. A connector as claimed in Claim 3 or Claim 4 wherein the linkage comprises a light emitting component, a non-electrically-conducting medium, and a light receiving component, said linkage being such as to prevent radio frequency energy from passing from the mobile phone to the loudspeaker or microphone.
11. A connector as claimed in Claim 10 wherein the non-electrically-conducting medium comprises a length of optic fibre.
12. A connector as claimed in Claim 10 wherein the light receiving component comprises a photo-diode.
13. A connector as claimed in Claim 10 wherein the linkage comprises an opto- isolator device in which a light emitting component is in direct proximity to a light receiving component.
14. A connector as claimed in Claim 13 wherein the light receiving component in the opto-isolator device comprises a photo-diode.
15. A method of isolating a mobile phone user's body from radio frequency energy generated by a mobile phone, said method comprising the incorporation, in the apparatus between the mobile phone and the user, of a linkage comprising a light emitting component, a non-electrically-conducting medium, and a light receiving component.
16. A method as claimed in Claim 15 wherein the non-electrically-conducting medium comprises a length of optic fibre.
17. A method as claimed in Claim 15 wherein the light receiving component comprises a photo-diode.

<Desc/Clms Page number 6>
18. A method as claimed in Claim 15 wherein the linkage comprises an opto- isolator device in which a light emitting component is in direct proximity to a light receiving component.
19. A method as claimed in Claim 18 wherein the light receiving component in the opto-isolator device comprises a photo-diode.
20. A mobile phone headset substantially as herein described and illustrated in the accompanying drawings.
21. A method, substantially as herein described and illustrated in the accompanying drawings, of isolating a mobile phone user's body from radio frequency energy generated by a mobile phone.