Condensed Consolidated Statements of Operations (USD $)	3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Income Statement [Abstract]
Net sales	$ 90,953,000	$ 113,361,000
Cost of sales	49,150,000	62,081,000
Gross profit	41,803,000	51,280,000
Expenses:
Selling, general and administrative	16,810,000	24,118,000
Research and development	10,049,000	9,684,000
Amortization of intangibles	1,582,000	1,719,000
Total operating expenses	28,441,000	35,521,000
Operating income	13,362,000	15,759,000
Other expenses (income):
Interest expense	2,111,000	2,146,000
Interest income and other	(276,000)	(496,000)
Income before provision for income taxes	11,527,000	14,109,000
Provision for income taxes	4,092,000	1,508,000
Net income	$ 7,435,000	$ 12,601,000
Net income per share:
Basic	$ 0.43	$ 0.54
Diluted	$ 0.36	$ 0.47
Weighted average number of common shares outstanding - basic	17,379,000	23,257,000
Weighted average number of common and common equivalent shares outstanding - diluted	23,444,000	29,147,000
Dividends declared per issued and outstanding common share as of the applicable dividend record date	$ 0.275	$ 0.275