Regular readers might have noticed a fair sprinkling of the odd term '1-seg' in news items over the last year or so, with all referring to Japanese products in some way.

From Sony's PSP and video Walkman to car satnav systems and mobile phones, the strangely named 1-seg mobile digital TV standard is popping up everywhere in the Far East, but what exactly is 1-seg?

First, a little background. 1-seg, as it's usually written in Japan, is the part of the ISDB-T digital terrestrial television broadcast spectrum intended exclusively for mobile devices.

Of the 13 'segments' that make up each digital ISDB-T channel, 12 are dedicated to full-bandwidth high-definition programming, leaving one to carry a much lighter mobile broadcast, which has become known as 1-seg.

Low-res, high impact

This MPEG-4 stream contains video, audio and interactive text elements, such as electronic programme guides and information on each show, in a stream that weighs in at just over 400Kbit/s. It makes 1-seg ideal for relatively low-powered handheld devices.

The fact that the highest possible video resolution is just 320 x 420 pixels underlines the difference between 1-seg and broadcasts for standard televisions.

Impressive as the 1-seg technology is though, we can't help wondering why watching TV on a tiny screen is so popular in Japan. After all, most attempts to deliver sports clips and the like to phones in the West have failed to take off.

User-friendly mobile phones

Sharp's Miyuki Nakayama explains part of the reason: "We were able to meet consumers' needs by releasing user-friendly phones. [These have included] Sharp's proprietary LCD technology, 1-seg tuner module and Cycloid display mechanism."

The Cycloid display (seen here on Sharp's 920SH handset) is a nifty way to allow the screen to swivel through 90 degrees to present a landscape-oriented face to the user. It's both practical and pleasingly tactile to play with, but we suspect Sharp's world-leading position in LCD manufacturing is even more significant.

Nakayama elaborates: "The brand image of Aquos LCD TVs has helped increase consumer recognition in Japan. [That's why] the handsets have been named Aquos keitai (mobile) here."

In fact, the Aquos tactic has been such an obvious success others have taken a leaf from Sharp's book. Sony has recently introduced Bravia-branded phones, while Panasonic is plundering its Viera intellectual-property cupboard to do the same.

The numbers don't lie

The facts are clear - 5 million sales by Sharp and twice that to the Japanese market as a whole - but who are the nerds watching these tiny TVs and how do they use them?

Somewhat surprisingly, market research by Japanese analyst Macromill just over a year ago shows that almost half (48.5 per cent) of 1-seg viewers are in their 40s and 50s, with the under-30s making up just 27.5 per cent. Not exactly the geek crowd many people anticipated.

On the other hand, fewer than a third of users are women, although this may be connected to viewing location. Over 80 per cent of 1-seg watching is done either at work or on the way there by public transport. In traditionalist Japan, many women over 30 have left the workforce to marry and raise a family, which is sure to skew the figures towards their male counterparts.

As for what people watch, news shows top the list at 75 per cent, followed by variety and sport broadcasts at around 35 per cent each (multiple answers allowed). Throw in the fact that only 15 per cent of viewers watch more than 30 minutes of 1-seg a day and it's clear the typical user tunes in for quick catch-up blasts on the train or bus.