Accrued liabilities components (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Accrued Liabilities Components Details
Bonuses	$ 724,000	$ 1,214,000
Payroll and payroll taxes	427,000	590,000
Compensated absences	384,000	508,000
Deferred rent credit	187,000	261,000
Warranty	206,000	490,000
Adverse purchase commitments	634,000	134,000
Accelerated rent expense	109,000	402,000
Professional fees	533,000	415,000
Purchased patents	0	330,000
Other	803,000	769,000
Accrued liabilities	$ 4,007,000	$ 5,113,000