IF THERE'S one thing guaranteed to ruin a night out at the cinema or the theatre it is some irritating ingrate who refuses to switch off their mobile phone. Well, now the outraged, put-out and frustrated have a powerful ally onside - the mighty Bill Gates, the world's third richest man and the founder of Microsoft.

Microsoft has just filed a patent in the US for a new technological concept called "digital manners". The system will prevent mobile phones from working in "socially undesirable" ways: in other words, ringing at the climactic scene of a summer blockbuster.

If rolled out, the computing giant says the new software could even halt sleazy phone users taking secret pictures - so-called "upskirt shots" - of women in public places, and end the fear among what Microsoft calls "ill-at-ease locker room patrons" that a camera phone could be used to snap clandestine photos of them while changing in a public place such as a swimming pool or gym.

The patent application says: "These and other examples illustrate some of the security and privacy concerns resulting from mobile devices, such concerns ranging from unintentional rudeness to critical security and privacy matters.

"Such mobile device intrusions may be summarised as socially undesirable audible, or visual disturbance, or unauthorised information or data capture."

The system will work by putting a digital manners server in place that will then transmit instructions to mobile devices. If a person enters a classical music concert, their phone will switch itself to silent, or if they walk into a restricted area, such as a Ministry of Defence site, they will be prevented from taking photographs.

Julian Calvert, who lectures on journalism at Glasgow Caledonian University and is chairman of the Society of Editors (Scotland), said the device could have benefits, particularly for those who value their privacy, such as the mega-rich or celebrities, who could put a digital exclusion zone around themselves.

He said: "One of the issues with camera phones is that they deny privacy, particularly to celebrities, so if any famous person is out for a meal or in a restaurant they now don't have to worry about the paparazzi when inside, but rather anyone else with a camera phone.

"Potentially, the more exclusive places could use this to guarantee the security and privacy of their clients. In the defence sector camera phones are quite a big problem for all sorts of security reasons. People can walk in with a camera phone in a way they couldn't with a full-on conventional camera."

A spokesman for Microsoft said: "Microsoft would provide guidance to customers on the recommended use that would be consistent with the high public privacy standards that Microsoft uses to develops its own products and services."

However, if these devices did become commonplace market forces could ensure that they don't have their intended effect: if someone was annoyed by digital manners, they could simply buy a brand that didn't use the technology.

Professor Chris Johnson, from the computing science department of Glasgow University, said: "There are lots of devices that don't run Microsoft software these days, and just like that, a lot of devices wouldn't use digital manners.

"Unless Microsoft makes it in the interest of people to buy a device with this technology, nobody's going to bother buying things that use it. I can't see a huge marketplace for digital manners at the moment."