CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 7,980,000	$ 4,550,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,147,000	1,292,000
Non-cash operating lease expense	300,000	287,000
Provision for doubtful accounts	122,000	174,000
Deferred taxes	286,000	388,000
Foreign currency transaction (gains) losses	(195,000)	16,000
Share-based compensation	726,000	671,000
Unrealized loss (gain) on available-for-sale equity security	12,000	(12,000)
Changes in operating assets and liabilities:
Accounts receivable	(8,351,000)	(7,303,000)
Inventories	(2,710,000)	(3,493,000)
Prepaid expenses and other assets	(1,194,000)	(117,000)
Accounts payable	2,714,000	6,024,000
Advance customer payments and other	79,000	133,000
Accrued expenses	(597,000)	456,000
Operating leases	(429,000)	(409,000)
Net cash provided by (used in) operating activities	(110,000)	2,657,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	5,098,000	6,083,000
Proceeds from sales of available-for-sale marketable securities	0	225,000
Purchases of available-for-sale marketable securities	(9,086,000)	(6,775,000)
Additions to equipment and leasehold improvements	(908,000)	(936,000)
Additions to patents	(72,000)	(159,000)
Net cash used in investing activities	(4,968,000)	(1,562,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	239,000	67,000
Tax payments for shares withheld related to stock option exercises	(1,000)	0
Net cash provided by financing activities	238,000	67,000
Effects of exchange rate changes on cash and cash equivalents	32,000	6,000
Net (decrease) increase in cash and cash equivalents	(4,808,000)	1,168,000
Cash and cash equivalents – beginning of period	13,684,000	8,399,000
Cash and cash equivalents – end of period	$ 8,876,000	$ 9,567,000