Magnetic Ink Character Recognition
Specially formatted characters are printed in a magnetic ink on the
document. When the characters are passed through a magnetic field each produces
a unique effect on the field and so is detected. MICR is accurate (few reading
errors) is unaffected if the source document is dirty or creased and it is
difficult to tamper with the data stored. It is however expensive to print the
characters on the document. This method of data capture is used on cheques.
This is the only significant use of the method because of its cost.
A chequebook is pre-printed with bank sort code, customer account number
and cheque number. The value of the cheque is printed in MICR characters when
the clearing bank processes the cheque, before it is read by the computer.
All banks use MICR for processing cheques.
- Along the bottom of a cheque the bank’s sort code, customer account number and cheque number are encoded in special characters in magnetic ink.
- The amount of the cheque is encoded in magnetic ink when it is handed in at a bank.
- The cheques can then be processed extremely fast by high-speed MICR devices that read, sort and store the data on disk.
MICR has several advantages for processing cheques:
- It is hard to forge the characters
- The characters can be read even if the cheque is crumpled, dirty or smudged
- The characters are readable by humans, unlike bar codes
Magnetic Stripe Cards
A plastic card with a magnetic strip on the back. The strip stores data
that is read when the card is wiped through a reader. In the case of credit and
cheque cards the magnetic strip will contain the account number, the type of
card and the expiry date. Other uses of these cards includes security passes -
where the card opens an electronic lock and the data read from the card can be
used to keep track of where people have been - and sales promotions where
customers collect points on their card every time they buy something.
In security and banking applications the user will have a changeable PIN
number that is used to authorise the card's use. The PIN number is not stored
on the card but it is held in encrypted form on the processing device.
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