Hand Scan Biometric Time and Attendance Terminals - The Pro's and Cons by: James Bell

Hand scan recognition time clocks have been around for nearly 20 years. To use a hand scan time clock or access control terminal the user enters their ID and places their right hand on the platen (a flat reflective surface with guide posts which lie in between the users fingers) and the hand scan unit will quickly perform a match against a registered template and allow access or log attendance.

Hand scan technology uses a camera and a series of mirrors to build a three dimensional picture of the users hand. Using this image the processor in the time clock measures certain hand geometry such as the length and proportion of each finger which it converts into an algorithm. This mathematical representation of the hand is stored in a template and is used when matching the user during subsequent logging events.

The algorithm is adjusted periodically and because of this feature it compensates for changes in the size of the users hand over a period of time so, if the user gains or loses weight the device compensates. Interestingly the unit does depend on the user having a right hand with no fingers missing. Having said that, testing from my associates has shown that a left hand turned upside down will work correctly.

Hand scan terminals are an established technology but they are not widely used in either time and attendance or access control applications.Hand Scan technology is not impacted by scratches or cuts or scars on the users hands nor is it effected by dirty hands although dirt accumulating on the mirrors or platen will eventually cause misreads. This makes the hand scan a very effective biometric device.

Given that they are actually more reliable than most of the other alternatives it is surprising that they have not been more widely accepted. One possible explanation is that they are more expensive than most fingerprint readers and they have no embedded software so they cannot be used as a stand alone time clock. Additionally, the manufacturers have not assigned exclusivity to a time and attendance solution provider nor have they developed award interpretation software themselves.

Hand scan time clocks tend to be used in harsh environments when fingerprint units simply can't recognise users who frequently damage their fingers. Typical applications are manufacturing, mining and construction. In those environments they tend to be installed in a dust proof enclosure to prevent the mirrors and camera becoming impacted by dirt. Unfortunately those environments are also prone to accidental or deliberate mechanical shock which is likely to misalign the camera and cause issues with template recognition.

Because hand scan terminals do not have any useful embedded software for time and attendance it is important to find a supplier with award interpretation or attendance software that is integrated with the hand punch terminals. When selected this software provider you should ensure that they are an established hand scan solution provider as integration is never as straightforward as you might think and while it may appear to work in the short time there may be some hidden integration issues down the track.

In summary, hand scan technology when coupled with some decent third party software is a great alternative for harsh environments because it is quite faultless in its recognition capabilities. You will however , almost certainly need a good third party time and attendance provider and be aware that the hand scan terminals are not as robust as some of the alternative and will not take kindly to hard knocks from the occasional accidental or wilful attempt at damage.