(4) Scanners

A scanner or a digitizer is an input device that can be moved over a drawing or photograph to convert it into digital data. Photograph or drawing can be seen on the CRT screen or it can be printed on the paper. Hence, a scanner is performing the function of a photocopier ( though their technological mechanisms are different ). Therefore, the scanner directly can enter the data into the computer without keying ( i.e. typing from the keyboard) which is the advantage of a scanner.  

A portable Scanner

The following are the types of scanners :
( i ) Optical Character Readers (O.C.R.)
( ii ) Optical Mark Readers (O.M.R.)
( i ) Optical Character Reader ( O.C.R. )
An Optical Character Reader (O.C.R.) is a direct entry input device. It can detect alphanumeric characters printed on any paper.
A light source converts the alphabets, number and similar such characters into electrical signal which are then sent to the computer for processing. The text to be scanned should be illuminated by a low frequency light source.The reflected light from the text is received by the light sensitive cells (i.e. photocells ) and generates the signal depending on the type of text.
The scanning capacity of O.C.R. is several thousands characters per second. It is mostly used at the department stores to convert the retail tags and send the data to the computer for billing.