Other intangible assets with definite lives (Details) (USD $)	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Jan. 31, 2014
Other intangible assets with definite lives [Abstract]
Gross patents	$ 2,620,000		$ 2,600,000
Accumulated amortization	2,240,000		2,230,000
Amortization expense, next twelve months	37,800
Amortization expense, year two	47,300
Amortization expense, year three	43,500
Amortization expense, year four	40,400
Amortization expense, year five	31,400
Amortization expense, thereafter	180,000
Patent amortization expense	$ 13,000	$ 14,000