CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended
	Apr. 03, 2020	Mar. 29, 2019
Income Statement [Abstract]
Net sales	$ 35,187,000	$ 32,583,000
Cost of sales	10,427,000	8,403,000
Gross profit	24,760,000	24,180,000
Selling, general and administrative expenses:
General and administrative	7,969,000	6,837,000
Marketing and selling	11,028,000	10,143,000
Research and development	6,898,000	5,635,000
Total selling, general and administrative expenses	25,895,000	22,615,000
Operating income (loss)	(1,135,000)	1,565,000
Other income (expense), net:
Interest income, net	216,000	271,000
Loss on foreign currency transactions	(468,000)	(248,000)
Royalty income	94,000	171,000
Other income, net	1,000	97,000
Total other income (expense), net	(157,000)	291,000
Income (loss) before income taxes	(1,292,000)	1,856,000
Provision (benefit) for income taxes	(1,158,000)	489,000
Net income (loss)	$ (134,000)	$ 1,367,000
Net income (loss) per share:
Basic	$ 0.00	$ 0.03
Diluted	$ 0.00	$ 0.03
Weighted average shares outstanding:
Basic	44,953	44,235
Diluted	44,953	46,913