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The purpose that bar code detects and method
From;    Author:Stand originally

1, the purpose that bar code detects
Bar code is carrier of a kind of data, it is having main effect in information transmission process, if bar code gives an issue, the communication of goods news will be interrupted. Because this must undertake be controllinged effectively to bar code quality, ensure bar code symbol is being supplied can be read by accurate knowledge on catenary, and a when this goal achieves when bar code detects effective tool. The target that bar code detects should check bar code symbol to whether can have its due effect namely, its main task is:
   •Make the person that the symbol pressworks right the product undertakes checking, so that be adjusted according to the result of the examination,produce a course with control.
   •ForecastBar codescanning knowledge reads function. Detect through bar code, we can satisfy the degree of symbolic standard to undertake evaluating to bar code symbol, and the knowledge of this kind of degree and bar code symbol reads function to having close connection.

2, law of check proved recipe
  Bar code examinesOvercoming a tradition to detect on the foundation of methodological blemish, already developed at present use bar code overall quality to classification law, namely " reflectivity curve analyses a way " . Scanning reflectivity curve and referenced coding algorithm have ground of integrated grading rules analysis, judgement, change apparent blemish into blemish (Defects) , the brim decides wait for parameter. Those who examine to give out as a result is the grade of bar code symbol, indicate the applicable situation of bar code symbol.
Curve of 2.1 scanning reflectivity
Scanning reflectivity curve is when scanning to symbol of a bar code with the scanner, the scanner explores the reflectivity of bar code symbol, reflectivity value and scanning position are concerned. If scanning beam is perpendicular at linear, criterion reflectivity is Esau draw start be end points, the distance of symbol of across and whole bar code (or linear position) function. Represent distance or linear position with the abscissa, represent reflectivity with ordinate, the reflectivity in can drawing scanning process is worth the relation curve with linear position namely curve of reflectivity of so called scanning, see figure below.

2.2 relevant term and definition
  •Lowermost reflectivity (R Min) : The reflectivity of the lowest on scanning reflectivity curve is worth.

   •Highest reflectivity (R Max) : The highest reflectivity on scanning reflectivity curve is worth.
   •Symbolic contrast (SC) : The difference of the highest reflectivity of scanning reflectivity curve and lowermost reflectivity. .

   •Total threshold value (GT, Global Threshold) : In order to is divisional on scanning reflectivity curve, reflectivity of empty a standard is worth. Those area that scanning reflectivity curve includes in place of upper part of line of total threshold value, namely empty; In those area that place of lower part of line of total threshold value includes, namely. Or.
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