Other intangible assets with definite lives (Details) (USD $)	Oct. 31, 2013	Jan. 31, 2013
Other intangible assets with definite lives [Abstract]
Gross patents	$ 2,580,000	$ 2,550,000
Accumulated amortization	2,220,000	2,180,000
Amortization expense, next twelve months	12,400
Amortization expense, year two	47,300
Amortization expense, year three	44,100
Amortization expense, year four	40,300
Amortization expense, year five	37,200
Amortization expense, thereafter	$ 179,400