Panel suppliers for Apple's 9-inch iPad line are seeing an as high as 20% decrease in orders during the fourth quarter of 2012 while orders for Apple's iPad mini are continuing to climb, according to industry sources.

The amount of panel area used in producing 7-inch tablet panels compared to the amount used in 9-inch ones is substantially less and will most likely affect revenues panel makers in Apple's iPad supply chain accumulate from tablet panel sales from the fourth quarter onwards, said the sources.

The sources also revealed that back in October 2012, nearly 75% of iPad sales were for the iPad mini while the rest were mainly for fourth and third generation iPads and that they expect iPad mini panel orders to exceed 9-inch ones throughout 2013.

Meanwhile, Digitimes Research estimates that 7-inch tablets will reach 75.6 million in sales during 2013, up 174% on year while 9-inch ones will drop from 60.3 million units in 2012 to 41.2 million in 2013, down 28% on year.