CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands		12 Months Ended
		Jan. 01, 2021	Jan. 03, 2020	Dec. 28, 2018
Income Statement [Abstract]
Net sales		$ 163,460,000	$ 150,185,000	$ 123,954,000
Cost of sales		45,098,000	38,231,000	32,444,000
Gross profit		118,362,000	111,954,000	91,510,000
Selling, general and administrative expenses:
General and administrative		33,911,000	29,313,000	24,287,000
Selling and marketing		45,764,000	45,491,000	38,600,000
Research and development		31,918,000	25,298,000	22,028,000
Total selling, general and administrative expenses		111,593,000	100,102,000	84,915,000
Operating income		6,769,000	11,852,000	6,595,000
Other income (expense), net:
Interest income, net		238,000	988,000	165,000
Gain (loss) on foreign currency transactions	[1]	864,000	(517,000)	(836,000)
Royalty income		440,000	551,000	633,000
Other income (loss), net		(44,000)	152,000	82,000
Total other income, net		1,498,000	1,174,000	44,000
Income before income taxes		8,267,000	13,026,000	6,639,000
Provision (benefit) for income taxes		2,354,000	(1,022,000)	1,671,000
Net income		$ 5,913,000	$ 14,048,000	$ 4,968,000
Net income per share:
Basic		$ 0.13	$ 0.32	$ 0.12
Diluted		$ 0.12	$ 0.30	$ 0.11
Weighted average shares outstanding:
Basic		45,605	44,493	42,587
Diluted		47,953	46,895	45,257

[1] Shown as a separate line item on the Consolidated Statements of Income.