Document processingGeneric MICR Fundamentals Guide 5-5Types of reader sortersThe following recognition technologies have been incorporatedinto MICR reader sorter devices.Waveform reader sortersWaveform reader sorters measure the magnetic signal waveformor pattern of the MICR character as the documents pass theread head. Waveform reader sorters are often referred to as“single slot” or “single gap” readers because the read headcontains one magnetically sensitive slot or gap, which covers theheight of the entire character string in the clear band. Each MICRcharacter that passes the read slot produces a waveform signal.This signal is compared against the known waveforms of theMICR character set to determine which character was read.Waveform reader sorters are also called “DC readers,” becausethey use a constant magnetic field to magnetize the characters.Waveform reader sorters are generally low to medium speedreading devices. The reject rates for these readers is slightlyhigher than for matrix readers.Matrix or AC reader sortersMatrix readers use a series of small read heads that are stackedin close proximity, each of which reads a small strip of thecharacter string. The segments of the MICR characters registeras binary magnetic flux transitions at each read head. Thesepulses are combined and used to build a two dimensional bitmapfor each character. This bitmap is then compared to knownbitmap patterns to determine the identity of the character.To simplify bitmapping, readings from groups of heads arelogically combined to produce a single value. This slightlyincreases sensitivity to spots, but results in lower reject rates formatrix readers.Matrix readers are also called “AC readers,” because they usean oscillating magnetic field to magnetize the characters. Theseoscillations cause a series of waveform peaks in a characterstroke, which are recorded as a binary 1 in the bitmap image ofthe character.
