Purchased Patents

9 Months Ended

Sep. 30, 2012

Purchased Patents

Purchased Patents

5. Purchased Patents

The Company acquired certain patents in 2005. The following sets forth the gross carrying amount and related accumulated amortization of the patents (in thousands):

						September 30, 2012
		December 31, 2011				(unaudited)
	Weighted-	Gross Carrying		Accumulated		Gross Carrying		Accumulated
	Average Life	Amount		Amortization		Amount		Amortization
		(in thousands)
Purchased Patents	10.0	$	2,292	$	1,380	$	2,292	1,552

Amortization expense was approximately $57,000 for the three months ended September 30, 2011 and 2012 and was approximately $172,000 for the nine months ended September 30, 2011 and 2012. The net book value of intangible assets as of December 31, 2011 and September 30, 2012 was approximately $0.9 million and $0.7 million, respectively.