Consolidated Condensed Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 30, 2011	Oct. 31, 2010	Oct. 30, 2011	Oct. 31, 2010
Consolidated Condensed Statements Of Operations [Abstract]
Net sales	$ 123,944	$ 123,125	$ 376,569	$ 338,232
Cost of sales	50,537	49,304	150,588	139,932
Gross profit	73,407	73,821	225,981	198,300
Operating costs and expenses:
Selling, general and administrative	25,110	35,501	74,296	86,767
Product development and engineering	20,489	18,400	61,242	51,107
Intangible amortization and impairments	4,573	2,406	8,778	7,216
Total operating costs and expenses	50,172	56,307	144,316	145,090
Operating income	23,235	17,514	81,665	53,210
Interest and other income, net	729	3	172	508
Income before taxes	23,964	17,517	81,837	53,718
Provision for taxes (benefits)	(3,015)	1,412	5,138	7,149
Net Income	$ 26,979	$ 16,105	$ 76,699	$ 46,569
Earnings per share:
Basic	$ 0.41	$ 0.26	$ 1.18	$ 0.75
Diluted	$ 0.40	$ 0.25	$ 1.14	$ 0.73
Weighted average number of shares used in computing earnings per share:
Basic	65,440	62,493	65,180	61,950
Diluted	67,314	64,555	67,539	63,723