Card Reader Rails/Slot And Magnetic Head Protrusion - IDTECH SecureHead User Manual

Card Reader Rails/Slot and Magnetic Head Protrusion

When designing a card reader, engineers must consider the thickness of the media used. Magnetic media comes in
various thicknesses, but most readers use cards that are nominally 0.030 inches thick +/- 10%
do occur where the media is thinner, normally in specialized applications where the media can be as thin as 0.010
inches thick (such as the paper cards used for many parking lot paper tickets).
To accommodate media with minimum and maximum thicknesses, the slot needs to be a between 0.040 and 0.050
inches wide in an area a minimum of 0.5 inches on either side of the centerline of the magnetic head's gap (this
gap is located at the apex of the head's radius). The remaining portion of the rails (slot width) can be wider, but
never smaller; also remember that it is best to have the reference surface/wear-plate extend for a minimum of 1.5
inches from the magnetic head's gap.
1. Magnetic heads need to be able to rotate on a gimbal (refer to Figure 3 for an example) to compensate for
tilting cards, and therefore must have a minimum deflection. For credit/debit cards used in financial
transactions or other applications using standard thickness cards (0.030 inches +/- 10%), the magnetic head's
gap (the apex of the protruding radius) should be spaced within 0.010 +/- 0.003 inches from the opposing
rail/wall.
To ensure reliable read rates on thinner cards, the head must contact the media and be deflected by a
minimum of 0.007 inches (0.18mm); this is regardless of the media thickness, or head configuration. For
example, if the media is 0.010 inches (0.25mm) thick, the head face must be positioned a maximum of 0.003
inches (0.08mm) from the opposite wall. To avoid damaging the gap material the head should not contact the
opposing rail/surface in the card slot.
Note: 0.030-inch thickness is the dimension for all credit and debit cards, and is common for other cards as well.
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SecureHead SPI Interface with FPC User Manual
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. Some applications
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