1、Designation: F1851 98 (Reapproved 2009)Standard Practice forBar Code Verification1This standard is issued under the fixed designation F1851; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in par
2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes a specific procedure for using abar code verifier to measure and quantify the optical andsymbology characteristics relative
3、to the print quality of a barcode symbol and its performance within a bar code readingsystem. Measurements taken with bar code verifiers shouldconform to ANSI ANS X3.1821995 R methodology. Vari-ous printing methods including direct thermal, thermal transfer,electrophotographic, dot matrix, and ink j
4、et methods are usedto produce bar code symbols. Use of this procedure will helpassure repeatability of measurements between operators andpieces of equipment and traceability of those measurements.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses
5、 are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safe
6、ty and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F1294 Terminology Relating to Automatic IdentificationHard Copy Printing Systems2.2 ANSI Standard:ANSIANS X3.1821995 R Bar Code Print Quality Guide-line32.3 AIM
7、Standard:AIM USA Laymans Guide to ANSI Print Quality42.4 Military Standard:MIL-STD 105E Sampling Procedures and Tables for Inspec-tion by Attributes53. Summary of Practice3.1 Printed bar codes can be analyzed with commerciallyavailable bar code verifiers to generate measurement valuesrelative to pri
8、nt quality. Verifiers can have various optical inputdevices and operate in varied spectral ranges with apertures ofdiffering sizes. The validity of the results of verification can beaffected greatly by the selection of the equipment, spectralresponse and aperture size, as well as the operators use o
9、f theequipment. Reporting structure of the test results (symbolgrade) only has meaning when the measuring aperture numberand nominal wavelength also are specified. The methodologycontained within this test method offers both a standard seriesof procedures for equipment set-up and use, and generalrec
10、ommendations, guidelines and information on bar codeverification.4. Significance and Use4.1 This test method provides a way to measure andquantify bar code print quality using commercially availablebar code verifiers. Possible uses include the following.4.1.1 Performance comparisons between media su
11、pplied bydifferent manufacturers.4.1.2 Performance comparisons between imaging materialssupplied by different manufacturers.4.1.3 Performance comparisons between printers suppliedby different manufacturers.4.1.4 Performance comparisons between different printingmethods.4.1.5 Research and development
12、 evaluation of developmen-tal coatings, ribbons and media for various printing methodsfor bar code imaging.4.1.6 Manufacturing process control can use this testmethod to audit product performance.5. Interferences5.1 To avoid interference from external causes, nolaminates, overcoats or protective mat
13、erials should be used on1This practice is under the jurisdiction of ASTM Committee F05 on BusinessImaging Productsand is the direct responsibility of Subcommittee F05.03 onResearch.Current edition approved Oct. 1, 2009. Published October 2009. Originallyapproved in 1998. Last previous edition approv
14、ed in 2003 as F1851 98(2003).DOI: 10.1520/F1851-98R09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Availa
15、ble from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from AIM USA, 634 Alpha Dr., Pittsburgh, PA 15238.5Available from Standardization Documents Order Desk, Bldg. 4D, 700 RobbinsAve., Philadelphia, PA 19111-5094.Copyright
16、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesNOTICE: This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International (www.astm.org) for the latest information1or over the samples. These may cause
17、 verification results thatare not characteristic of the process being tested.5.2 The equipment selected should be set-up, programmed(if necessary) and calibrated to the manufacturers recommen-dations.NOTE 1This is extremely important as improper use of verificationequipment through incorrect set-up
18、or calibration, or both, can causemisleading results.5.3 To avoid interference caused by operating power volt-age fluctuations, the equipment used should be operated usingthe power source recommended by and in the manner recom-mended by the manufacturer. In the event results can vary withvariation i
19、n supply power, such as if the unit operates solelyfrom batteries, it should be determined what results variationscan be expected, based upon the manufacturersrecommendations, and appropriate compensation should bemade.6. Procedure6.1 Calibration/Traceability:6.1.1 Proper calibration is an essential
20、 aspect of the opera-tion of a bar code verifier. It is imperative that the operatorproperly and carefully follow the manufacturers proceduresfor calibration of the verifier. Frequency of calibration shouldbe recommended by the manufacturer, and calibration at afrequency greater than recommended may
21、 ensure higher accu-racy and repeatability.6.1.2 To assist in determining if a verifier is being operatedwithin the ANSI ANS X3.1821995 R, bar code calibrationor correlation standards are available.66.2 Test Materials:6.2.1 Test specimens should be characteristic or representa-tive of output from a
22、specific process. Appropriate bar codesymbols should be imaged on the media to be tested.6.2.2 Test specimens and samples should be handled withcare. Defects in the samples should be characteristic of theprocess being tested and not due to handling of the specimens.6.3 Equipment Selection and Use6.3
23、.1 Bar code verifiers can consist of various pieces ofequipment with differing capabilities and features. Usersshould select a device that meets the operational, application,and specification requirements of their application. Particularattention should be paid to what application or industrystandar
24、d(s) the device must measure against and that theoptical input device be matched to the type of materials to betested.6.3.2 The aperture size and wavelength has a significantimpact as to the grade results obtained. The ANSI GuidelineX3.1821995 R recommends the aperture diameter based onthe “X” dimen
25、sion of the bar code being verified. The apertureand wavelength specified in industry application standardstakes precedence over the ANSI guideline, even if some “X”dimension ranges do not agree with the ANSI recommenda-tions. If measuring aperture diameter is not specified, selectaperture diameter
26、based upon theANSIANS X3.1821995 Rrecommendations shown below.Diameter 9X9 Dimension (in 0.0010 in.) Range0.0030 in. 0.0040 to 0.007 in.0.0050 in. 0.0071 to 0.013 in.0.0100 in. 0.0131 to 0.025 in.0.0200 in. 0.0251 in. and larger6.3.3 The equipment selected should be set-up,programmed, if necessary,
27、and calibrated to the manufacturersrecommendations.NOTE 2This is extremely important as improper use of verificationequipment through incorrect set-up, or calibration, or both, can causemisleading results.6.3.4 Care should be taken in the selection of the locationwhere verification is performed. The
28、 operator should be awareof unusual ambient light conditions that may affect readings.Additionally, calibration of the device should be performedunder the same ambient lighting conditions as those where thetesting will be performed. The infinite pad method referencedin ANSI ANS X3.1821995 R should b
29、e used to preventoptical affects caused by the opacity of the sample substrate. Inthe absence of materials for the infinite pad method, an opaqueblack matte surface can be used under the test sample toprovide a worse case optical situation.6.3.5 Bar code symbols should be scanned in both direc-tions
30、 (left to right and right to left) and over numerous areas ofthe symbol. This practice will ensure a better overall indicationof the bar code symbols total quality.6.3.6 Operator proficiency can influence the results. Opera-tors must be trained and care should be taken in all testingsituations. It i
31、s recommended that statistical methods beemployed to reduce the effects of operator variability and thatoperators undergo periodic retraining. As a quality measure-ment function, bar code verification should be approached thesame as any other quality control or quality monitoringfunction.6.3.7 ANSI
32、ANS X3.1821995 R specifies ten scans of asymbol are required to obtain a symbol grade. The number ofsymbol grades or scans taken from a particular test sampleshould be based upon statistical methodology to ensure theresults meet the necessary levels of confidence required. Pleaserefer to MIL-STD 105
33、D for guidance on sampling levels andtechniques.7. Report7.1 A Scan Reflectance Profile (SRP) is a record of thereflectance values (0 % to 100 %) measured along a single lineacross the entire width of the bar code. These values arecharted to create an analog representation of the bar code. Thescan r
34、eflectance profile grading method identifies relativelevels of print quality. Each SRP will be graded as A, B, C, D,or F (Scan Grade) for one or possibly more of specified criteria.The grading scheme follows academic letter gradesA, B, C, D,6As an adjunct to the ANSI standard, the Uniform Code Counc
35、il and AIM USA,created a unique set of primary and secondary Bar Code Calibration Standards inconjunction with Applied Image, Inc. These bar code standards are calibrated toANSI Methodology and traceable to NIST. Though verifier manufacturers also mayhave NIST traceable calibration/correlation stand
36、ards available, the sole source ofsupply of these test standards known to the committee at this time isApplied Image,Inc., 1653 East Main Street, Rochester NY 14609. If you are aware of alternativesuppliers, please provide this information to ASTM Headquarters. Your commentswill receive careful cons
37、ideration at a meeting of the responsible technicalcommittee,1which you may attend.F1851 98 (2009)2and F whereAis the best grade and F the lowest.After creatingthe SRP, a count of the elements (bars and spaces) determinesif the bar code conforms to some type of symbology, but beforethis can be accom
38、plished, edge determination must be done.7.1.1 Edge DeterminationA Global Threshold is estab-lished halfway between the highest reflectance value and thelowest reflectance value seen in the profile. Edge determinationis done by counting the number of crossings at the GlobalThreshold confirming wheth
39、er the count conforms to or isconsidered nonconforming to a legitimate bar code symbology.If the bar code conforms it PASSES (Grade A); if it isconsidered nonconforming it FAILS (Grade F). The formula isas follows:GT = Rmin+ SC/2,Rmin= Reflectance Min, andSC = Symbol Contrast.7.1.2 DecodeA bar code
40、will PASS on Decode when theestablished bar and space widths can be converted into thecorrect series of valid characters using the Reference Decodealgorithm for a given symbology and or application and isgraded Pass (A) or Fail (F).7.1.3 Minimum Reflectance (Rmin)The reflectance valuefor at least on
41、e bar must be half or less than the highestreflectance value for a space and is graded Pass (A) or Fail (F).The formula is as follows:Rmin .5 Rmax= PASS, Rmin.5Rmax= FAILwhere:Rmin= Reflectance min, andRmax= Reflectance max.7.1.4 Minimum Edge Contrast (ECmin)Each transitionfrom a bar to a space, or
42、back again, is an “edge” whosecontrast is determined as the difference between peak values inthat space and that bar. The edge that has the minimum contrastfrom the transition from space reflectance to bar reflectance, orfrom bar to space, is the Minimum Edge Contrast or ECminandis graded Pass (A) o
43、r Fail (F). The formula is as follows:ECmin= Rsmin Rbmax(worst pair)where:Rs = Space Reflectance, andRb = Bar Reflectance.7.1.5 Symbol Contrast (SC)Symbol contrast is the differ-ence between the highest reflectance value and the lowestreflectance value in the scan profile and is graded A, B, C, D,or
44、 F. The quantitative criteria for the symbol contrast grades aregiven in ANSI ANS X3.1821995 R. The formula is asfollows:SC=RmaxRminwhere:SC = Symbol Contrast,Rmax= Reflectance Max, andRmin= Reflectance Min.7.1.6 Modulation (MOD)Modulation has to do with howa scanner sees wide elements (bars or spac
45、es) in relationship tonarrow elements, as represented by reflectance values in thescan profile. Scanners usually see spaces narrower than bars,and scanners typically see narrow spaces being even lessintense or not as reflective as wide spaces and is graded A, B,C, D, or F. The quantitative criteria
46、for the modulation gradesare given in ANSI ANS X3.1821995 R. The formula is asfollows:ECmin/SCwhere:ECmin= Edge Contrast Min, andSC = Symbol Contrast.7.1.7 DefectsDefects are voids found in bars or spotsfound in the spaces and quiet zones of the code. Voids, spots,smudges, and other defects in bar c
47、ode symbols can yield poorscanning results, and thus, will yield lower verification results.Each element is evaluated individually for its reflectancenonuniformity. Element reflectance nonuniformity is the dif-ference between the highest reflectance value and the lowestreflectance value found within
48、 a given element and is gradedA,B, C, D, or F. The quantitative criteria for the defect grades aregiven in ANSI ANS X3.1821995 R. The formula is asfollows:ERNmax/SCwhere:ERNmax= Element Reflectance Nonuniformity, andSC = Symbol Contrast.7.1.8 DecodabilityDecodability is the measure of theaccuracy of
49、 the printed bar code against the appropriatereference decode algorithm. Each symbology has publisheddimensions for element widths and provide margins or toler-ances for errors in the printing and reading process. Decod-ability measures the amount of margin left for the readingprocess after printing the bar code. Different decodabilitycalculation methods are used for each type of symbology beingtested. The decodability calculations are programmed into theverifiers, and decodability is graded A, B, C, D, or F accordingto the
