The pre-Macworld Expo rumour season has begun in earnest, with new reports claiming an Apple sub-notebook Mac's set for introduction at the show next January.

The device is predicted to be thin and based on solid-state flash memory. Smaller than a MacBook, it is widely expected the sub-notebook Mac will offer a sizeable drive, though its lack of moving parts will make for a robust system with low power demands.

Speculation about the device grew with news from DigiTimes, which reports Apple is not accepting increased deliveries of LED backlight units.

DigiTimes claims Apple has placed orders for LED backlights with Kenmos Technology and Taiwan Nano Electro-Optical Technology. And has booked 90,000 shipments in December, driving rumours of the sub-notebook Mac.

This report should be considered in combination with Apple's environmental commitment made this year, in which the company promised to migrate all its screens to LED in the immediate future.

The move from fluorescent to LED backlighting eliminates mercury from the display assembly and reduces power demands.