7. EQUITY COMPENSATION PLANS (Details - Share based compensation) - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Share based compensation	$ 1,283,000	$ 1,616,000	$ 3,740,000	$ 5,280,000
Cost of contract manufacturing [Member]
Share based compensation	20,000	16,000	42,000	48,000
Research and development [Member]
Share based compensation	580,000	685,000	1,620,000	2,288,000
Selling, general and administrative [Member]
Share based compensation	683,000	915,000	2,078,000	2,944,000
Stock Options [Member]
Share based compensation	1,208,000	1,561,000	3,555,000	5,086,000
ESPP [Member]
Share based compensation	$ 75,000	$ 55,000	$ 185,000	$ 194,000