Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 29, 2012	Feb. 28, 2011	Feb. 29, 2012	Feb. 28, 2011
Condensed Consolidated Statements Of Operations
Net sales	$ 2,855	$ 4,242	$ 10,845	$ 9,988
Cost of sales	1,747	2,637	6,807	6,085
Gross profit	1,108	1,605	4,038	3,903
Operating expenses
Selling, general and administrative	1,525	1,486	4,654	4,499
Research and development	933	1,039	3,054	3,377
Gain on bankruptcy claim	0	0	0	(155)
Total operating expenses	2,458	2,525	7,708	7,721
Loss from operations	(1,350)	(920)	(3,670)	(3,818)
Interest income	0	0	0	3
Gain on sale of long-term investment	0	0	990	0
Other income (expense), net	7	(30)	53	593
Loss before income tax expense (benefit)	(1,343)	(950)	(2,627)	(3,222)
Income tax expense (benefit)	18	(4)	(17)	7
Net loss	$ (1,361)	$ (946)	$ (2,610)	$ (3,229)
Net loss per share - basic	$ (0.15)	$ (0.11)	$ (0.29)	$ (0.37)
Net loss per share - diluted	$ (0.15)	$ (0.11)	$ (0.29)	$ (0.37)
Shares used in per share calculations:
Basic	9,055	8,828	8,989	8,742
Diluted	9,055	8,828	8,989	8,742