Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014
Income Statement [Abstract]
Net sales	$ 71,633,000	$ 88,905,000	$ 229,826,000	$ 257,772,000
Cost of sales	39,325,000	50,559,000	124,318,000	145,679,000
Gross profit	32,308,000	38,346,000	105,508,000	112,093,000
Expenses:
Selling, general and administrative	15,005,000	17,320,000	46,557,000	49,867,000
Research and development	8,582,000	8,899,000	28,267,000	25,664,000
Amortization of intangibles	1,561,000	1,560,000	4,682,000	4,724,000
Total operating expenses	25,148,000	27,779,000	79,506,000	80,255,000
Operating income	7,160,000	10,567,000	26,002,000	31,838,000
Other expenses (income):
Interest expense	72,000	1,993,000	406,000	6,009,000
Interest income and other	(107,000)	(256,000)	(281,000)	(757,000)
Income before provision for income taxes	7,195,000	8,830,000	25,877,000	26,586,000
Provision for income taxes	2,235,000	2,955,000	8,107,000	9,423,000
Net income	$ 4,960,000	$ 5,875,000	$ 17,770,000	$ 17,163,000
Net income per share (See Note 4):
Basic (in dollars per share)	$ 0.31	$ 0.39	$ 1.10	$ 1.08
Diluted (in dollars per share)	$ 0.30	$ 0.32	$ 1.08	$ 0.92
Weighted average number of common shares outstanding – basic (in shares)	16,202,000	15,200,000	16,220,000	15,882,000
Weighted average number of common and common equivalent shares outstanding – diluted (in shares)	16,382,000	21,764,000	16,468,000	22,324,000
Dividends declared per issued and outstanding common share as of the applicable dividend record date (in dollars per share)	$ 0.30	$ 0.30	$ 0.90	$ 0.875