Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2012	Jul. 31, 2011
Deferred tax effects of the Company's principal temporary differences
Allowance for doubtful receivables	$ 177	$ 192
Inventories	858	898
Basis difference in property and equipment	(5)	(6)
Intangible assets
Accrued warranty costs	50	47
Accrued expenses and other	115	135
Deferred revenue	(42)	(75)
Net operating loss carry-forwards	9,663	9,785
Valuation allowance	(10,816)	(10,976)
Total deferred tax asset