A new TV has been launched by Sony that automatically switches to an energy-saving 'picture off' mode when viewers leave the room.

Stocked by home furnishings retailer John Lewis, the 40-inch Eco TV has a built-in sensor that can detect body heat and movement.

If it notices that viewers have left the typical viewing range of the screen, it will switch into the low-power mode.

What's more, the intelligent television can be set up to switch to standby if no movement is detected within half an hour, ideal for people who are prone to nodding off during the soaps.

Depending upon the room's ambient lighting, the Sony TV will also adjust the brightness of its backlight to further limit its electricity consumption.

'The slim-line design of the TV means it requires less packaging and an on-screen operational manual cuts down on printed instructions,' added John Lewis.

Sony claims to have pursued a range of eco-initiatives in improving the energy efficiency of products such as its TVs and home office laptops.

The company's Vaio notebook computers use LCD screens with mercury-free LED lighting, which is more efficient than traditional screen backlights.

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