Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 12,751,000	$ 5,742,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,560,000	2,629,000
Non-cash operating lease expense	569,000	521,000
Provision (recovery) for doubtful accounts	124,000	(20,000)
Deferred taxes	983,000	366,000
Foreign currency transaction gains	(8,000)	(97,000)
Share-based compensation	1,347,000	1,181,000
Unrealized (gain) loss on available for sale equity security	(13,000)	18,000
Changes in operating assets and liabilities:
Accounts and trade notes receivable	(4,792,000)	1,888,000
Inventories	(8,221,000)	(5,212,000)
Prepaid expenses and other assets	9,000	49,000
Accounts payable	5,198,000	(1,903,000)
Advance customer payments and other	(177,000)	247,000
Accrued expenses	589,000	1,321,000
Operating lease liabilities	(830,000)	(772,000)
Net cash provided by operating activities	10,089,000	5,958,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	10,601,000	11,576,000
Proceeds from sale of available-for-sale marketable securities	225,000	0
Purchases of available-for-sale marketable securities	(13,639,000)	(13,186,000)
Additions to equipment and leasehold improvements	(1,627,000)	(1,527,000)
Additions to patents	(254,000)	(212,000)
Net cash used in investing activities	(4,694,000)	(3,349,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	428,000	358,000
Tax payments related to shares withheld for share-based compensation plans	(787,000)	(605,000)
Proceeds from issuance of common stock under employee stock purchase plan	247,000	224,000
Net cash used in financing activities	(112,000)	(23,000)
Effects of exchange rate changes on cash and cash equivalents	2,000	(23,000)
Net increase in cash and cash equivalents	5,285,000	2,563,000
Cash and cash equivalents – beginning of period	8,399,000	5,836,000
Cash and cash equivalents – end of period	$ 13,684,000	$ 8,399,000