Apple plans to completely overhaul its product lineups, including iPad, iMac, iPhone and MacBook Air, in 2012 and is expected to finalize order volumes for key parts and components for the next-generation iPad in December, according to sources in the upstream supply chain.

Inventory of key parts and components for the next-generation iPads will be sufficient enough for the production of two million units by year-end 2011, the sources pointed out.

Apple has asked makers in the supply chain to develop flat panel modules and LED light bars for two iPad prototypes, codenamed J1 and J2, the sources revealed.

TPK Holdings will begin to supply touch panels to Apple in November before Wintek starts shipping comparable models in December, added the sources.

However, the next-generation iPhone and iMac are unlikely to be revealed until the second half of 2012, the sources added.