Income taxes Income tax disclosure (Details) (USD $)	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Components of deferred income tax assets [Line Items]
Tax benefit of stock options exercised		$ 11,000	$ 0
Excess tax (benefit) expense from stock options exercised		11,000	(6,000)
Change in deferred tax assets valuation allowance	3,000,000	12,500,000
Deferred Tax Assets, Operating Loss Carryforwards, Domestic		3,680,000	3,728,000
Non-qualified deferred compensation		2,092,000	1,968,000
Federal operating loss carryforward expires		Jan. 31, 2030
Research tax credit		1,964,000	1,858,000
Deferred Tax Assets, Operating Loss Carryforwards, State and Local		1,066,000	921,000
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits		837,000	691,000
Accrued pension		428,000	578,000
Inventory valuation allowance		306,000	300,000
Other		94,000	225,000
Inventory uniform capitalization		132,000	128,000
Deferred tax assets, gross		16,631,000	16,899,000
Valuation allowance		(14,180,000)	(1,934,000)
Total deferred tax assets, net of valuation allowances		2,451,000	14,965,000
Equity Method Investment, Summarized Financial Information, Net Income (Loss)		2,680,000	3,189,000
Depreciation		1,041,000	1,733,000
Prepaid		340,000	319,000
Total deferred tax liabilities		1,381,000	2,052,000
Deferred income tax, net		1,070,000	12,913,000
Deferred tax assets - current		0	1,946,000
Deferred tax assets - long-term		1,766,000	10,967,000
Deferred tax liabilities - current		696,000	0
Operating Loss Carryforwards, Expiration Dates		expire at various times from 2013 to 2031
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration		14,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		1,297,000	1,300,000
Foreign NOL carryforward		2,241,000	2,726,000
Stock compensation		1,417,000	1,243,000
Other accruals not yet deducted		1,077,000	1,233,000
Current Fiscal Year End Date		--01-31
Foreign tax credit		(67,000)	(1,300,000)
Tax Credit Carryforward, Expiration Date			Jan. 31, 2022
Undistributed earnings of foreign subsidiaries		17,000,000
Open Tax Year		2010
Open tax years up to the amount of research tax credit generated		January 31, 2002 through January 31, 2009
Additional Paid-in Capital
Components of deferred income tax assets [Line Items]
Excess tax (benefit) expense from stock options exercised		11,000	(6,000)
DENMARK
Components of deferred income tax assets [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		1,000,000
Middle East [Member]
Components of deferred income tax assets [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		1,200,000
Domestic Tax Authority [Member]
Components of deferred income tax assets [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Domestic		$ 12,400,000