Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Cash, FDIC Insured Amount	$ 250,000			$ 250,000
Cash, Uninsured Amount	4,391,000			4,391,000				$ 4,488,000
Depreciation, Total	1,825,000		$ 1,725,000	5,569,000	$ 5,122,000
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset	0			$ 0
Standard Warranty Extended Term for Exceptions				10 years
Research and Development Expense, Total	$ 1,463,000		$ 144,700	$ 4,404,000	$ 4,117,000
Incremental Common Shares Attributable to Dilutive Effect of Contingently Issuable Shares	856,000		297,000	289,000	853,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	28.90%		32.00%	28.90%	30.40%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ 4,676,578
Income Tax Expense (Benefit), Total	$ 123,000		$ (406,000)	$ (3,867,000)	$ 677,000
Accounting Standards Update 2016-09 [Member]
Income Tax Expense (Benefit), Total				$ 92,996
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent						21.00%	27.60%
Scenario, Forecast [Member] | Transferred at Point in Time [Member] | Lighting Segment [Member]
Revenue from Contract with Customer, Including Assessed Tax, Percent of Revenue						90.00%
Minimum [Member]
Media Content Service Period				30 days
Finite-Lived Intangible Asset, Useful Life				7 years
Standard Warranty Term				1 year
Maximum [Member]
Media Content Service Period				1 year
Finite-Lived Intangible Asset, Useful Life				20 years
Standard Warranty Term				5 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment, Useful Life				15 years