The tablet PC category expanded its role in the mobile PC market, with shipments of 72.7 million units, accounting for 25.5% of mobile PC shipments in 2011, according to the latest NPD DisplaySearch report.

The year-over-year shipment growth rate for tablets in 2011 is expected to reach 256%, as strong tablet shipments in Q3 2011 appeared to be a prelude to equally vigorous demand in Q42011. Introductions of significantly competitive new devices in Q4 2011, strong demand for incumbents, and additional distribution channels have been catalysts for accelerated tablet PC shipment growth, NPD claims.

Tablet PC shipment growth is happening as NPD DisplaySearch has slightly lowered its notebook PC shipment forecast. Notebook PC shipments in 2011 are now expected to reach 187.5 million units, up 12% year-over-year, but slightly less than the previous forecast of 188 million. Mini-note PC shipments are expected to reach 25.2 million units, up 20% year-over-year. Overall mobile PC shipments in 2011 are projected to reach 285.4 million units, up 31% year-over-year.

“In the short term, tablet PCs will be the growth accelerant in the overall mobile PC market, as macroeconomic factors and hard drive motor supply issues impact the market for notebook PCs. In the longer term, notebook PC shipments will bounce back as ASPs continue to decline, Windows 8 launches, and new form factors, such as ultrabooks, continue to emerge,” said Richard Shim, senior znalyst at NPD DisplaySearch.

By 2017, notebook PC shipments are forecast to reach 432 million units, and tablet PC shipments are projected to reach 383.3 million units. Ultrabooks are an emerging form factor that is expected to contribute to demand in later years of the forecast. Demand for ultrabooks will be driven by consumer interest in sleek design and convenience like instant-on and long battery life. For the next two years, the premium price points of Ultrabooks will temper demand, and there may be some supply limitations in production of displays thin enough for Ultrabooks.”

Tablet PC shipments will be driven by increasingly powerful multi-core processors, mature operating systems, growing application libraries, and higher resolution panels. NPD DisplaySearch forecasts that tablet PCs with 250 to 300 pixel per inch panels will make up nearly 25% of shipments in 2012.

Mobile PC shipments into emerging regions are growing, with 2011 shipments projected to be 138 million units, up 48% year-over-year, and increasing to 452.8 million by 2017. Mobile PC shipments into mature regions are estimated to reach 147.5 million units in 2011 and grow to 371.6 million units by 2017.

Mobile PC shipments will be up in late 2012 and 2013 with the introduction of Microsoft’s Windows 8 operating system and new mobile processors from Intel.

Tags: Apple, iPad, Galaxy Tab, Samsung