Lucas-Fan | Electronic and Technology

Multi-Track Reader Characteristics

The multiple track reader employs a matrix of tiny, vertically aligned read heads to detect the presence of the magnetic flux pattern. The small individual read heads slice across the character to detect the presence of magnetic flux. This sensing of magnetic flux over time produces a unique matrix pattern for each character.

An OCR reader does not use magnetic properties to detect the E-13B characters. A photocell column detects the presence of the dark area of a character.

Waveform Theory

The readers move and read documents from right to left. The right-hand edge of the character, as a result, is the first to cross the read head. Analysis of the signal level created by reading the character 0 will help explain this in greater detail.

As the character moves from right to left under the read head, the gap detects the magnetism of the first right-hand edge (edge 1). This results in the increase in magnetism and a positive peak is created (peak 1).

At the second edge, the vertical read head detects a drop in magnetism, which results in a -110 signal level at peak 2. Again the waveform returns to zero until the next portion of the inner ring of the character is detected. At this point (peak 3), an increase in magnetism (+110) is indicated. Finally, the outer portion of the character is read, resulting in a negative peak (peak 4) of -130.

The placement of the vertical edges must occur in increments of 0.013 inches from the first right-hand edge. There are five characters that have two positive and two negative peaks similar to the character 0 and also appear in a positive-negative-positive-negative format. The peaks do require different amplitudes, but ANSI standards allow them to vary from 50% to 200% of the nominal amplitudes (Canadian standards allow them to vary from 80% to 200% of the nominal amplitudes).

What Affects the Signal Level?

Signal level can vary based on a number of factors. The amount of iron oxide (concentration) that is present in the character will affect the signal level.

The taller the vertical edge of the character, the taller the peak (either positive or negative). A vertical edge that is not regular and/or not vertical will result in a reduction in the amplitude of the peak and will flatten the peak out.

Keys to proper waveform detection are:

* All peaks in a character’s waveform must be detected.

* The peak must be located at or near its anticipated location.

* No significant “extra” peaks can be present.

* There cannot be wide variations in the signal levels of peaks within a character.

Printers that are used for MICR printing must have a unique MICR font that is modified to suit the unique printer engine, and it must be modified to the pixel level to match the magnetic toner provided for that printer. This is essential to ensure the correct waveform, dimension, and signal strength when a check is printed with the correct MICR characters. In addition, the MICR font must meet ABA-X9 standards to ensure acceptance of your checks by banking institutions.

The magnetic MICR toner that you choose must be specifically designed for the particular print engine in the printer. Ensure the toner has been thoroughly tested for consistent signal readings, image permanence and uniformity, and excellent edge acuity. Toner coverage must be solid with no extraneous toner lay down.

If you buy a “compatible” brand, ensure it has a new OPC drum, new primary charge rollers (PCRs), a new black velvet magnetic sleeve, and new image wiper blades. The hopper system must be filled with high-quality, low-abrasion MICR toner.

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