Condensed Consolidated Statements of Operations - USD ($)	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Income Statement [Abstract]
Net sales	$ 121,569,000	$ 135,786,000
Cost of sales	73,853,000	83,678,000
Gross profit	47,716,000	52,108,000
Expenses:
Selling, general and administrative	28,475,000	32,685,000
Research and development	13,750,000	14,096,000
Amortization of intangibles	5,269,000	6,055,000
Total operating expenses	47,494,000	52,836,000
Operating income (loss)	222,000	(728,000)
Other expenses (income):
Interest expense	2,588,000	3,325,000
Interest (income) and other	39,000	(2,000)
Loss before benefit from income taxes	(2,405,000)	(4,051,000)
Benefit from income taxes	(745,000)	(1,562,000)
Net loss	$ (1,660,000)	$ (2,489,000)
Net loss per share (See Note 4):
Basic (in dollars per share)	$ (0.07)	$ (0.11)
Diluted (in dollars per share)	$ (0.07)	$ (0.11)
Weighted average number of common shares outstanding – basic (in shares)	23,797,000	23,385,000
Weighted average number of common and common equivalent shares outstanding – diluted (in shares)	23,797,000	23,385,000
Dividends declared per issued and outstanding common share as of the applicable dividend record date (in dollars per share)	$ 0.10	$ 0.3