Application Scenarios

应用场景                                                                                                       

 POS生测试应用产过程中的,需要对磁头的位置进行标定验证，设备在实际工作中，因为人为因素可能造成浮高或者过低，这将考验磁头的读写能力，

LIMIT CARD根据实际生产状况，模仿实际工况，考验对POS机的工作过程进行验证，

   以下是原始参考资料

         Track Location Cards-Accuracy/Precision Note

        When we produce a Track Location Card which places the tracks, for example, at 0.8mm above the ISO centerline. we check the actual placement of the tracks in thefollowing way:

1. Apply magnetic viewing fluid on the magnetic stripe permitting a visual examinationof the encoded flux transitions.

2.A measuring microscope equipped with X & Y digital calipers with a instrumenterror of+ 0.003 mm.

3.The hairline of the microscope is targeted at the top reference edge of the card and theX caliper zeroed. The microscope stage is moved by means of the X caliper until thehairline is positioned at the top of the flux transitions on Track 2. We only measurethe top of Track 2 since the track width and other track positions are fixed (three trackhead). See below for head dimensions and measured distances

Note: Several accuracy & precision factors:

     The magnetic viewing fluid make the magnified flux transitions appear somewhat fuzzyand thus it is the microscope operator's judgment of where the tops of the flux transitionsare positioned. Part of what makes the flux transitions fuzzy is fringing from theencoding head. The three track encoding head track widths are stated as 0.110 + 0.003inches (2.794 +0.08 mm). Fringing effects cause the appearance of the flux transitions tomeasure 3.1 + 0.05 mm. The extent that the magnetic viewing fluid can be attracted to thedecreasing magnetic field in the fringe portion is a factor on where the flux transitions areviewed.

Key dimensions:

     Track 1, 2 or 3 width (head): 2.794  0.08 mmTrack 1, 2 or 3 width (measured): 3.06 + 0.05 mm

Gap between Track 1 and Track 2 (measured): 0.26  0.01 mmGap between Track 2 and Track 3 (measured): 0.46 +0.01 mm

Encode head moves laterally on stepper motor under software controlHead offset precision: 0.025 mm per step

Measured track position and expected tolerances from a Track Card with a 0.8 mm abovethe ISO centerline is shown on the next page.

Key Analysis

重点分析                                                                                                        

E

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