Income Taxes (Tax Effects of Temporary Differences) (Details) (USD $)	Jul. 31, 2014	Jul. 31, 2013
Deferred tax assets
Allowance for doubtful accounts receivable	$ 193,000	$ 217,000
Inventory and warranty reserves	8,125,000	7,559,000
Compensation and commissions	1,716,000	1,705,000
State and foreign research and experimentation credits	3,383,000	2,736,000
Stock-based compensation	4,859,000	8,068,000
Other	2,520,000	2,478,000
Less valuation allowance	(2,958,000)	(2,225,000)
Total deferred tax assets	17,838,000	20,538,000
Deferred tax liabilities
Plant and equipment	(486,000)	(1,424,000)
Intangibles	(10,322,000)	(10,187,000)
Total deferred tax liabilities	10,808,000	11,611,000
Net deferred tax assets	$ 7,030,000	$ 8,927,000