Significant accounting policies Other intangible assets with definite lives (Details) (USD $)	Jan. 31, 2015	Jan. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Patents, Gross	$ 2,700,000us-gaap_FiniteLivedPatentsGross	$ 2,600,000us-gaap_FiniteLivedPatentsGross
Finite-Lived Intangible Assets, Accumulated Amortization	2,280,000	2,230,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	52,029
Finite-Lived Intangible Assets, Amortization Expense, Year Two	48,201
Finite-Lived Intangible Assets, Amortization Expense, Year Three	45,176
Finite-Lived Intangible Assets, Amortization Expense, Year Four	36,189
Finite-Lived Intangible Assets, Amortization Expense, Year Five	33,193
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 183,410

Name:	us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References