Barcode Print Quality Inspection Standards: A Must-Read Guide for Flexible Packaging and Label Converters

I. Subject matter, scope and application

This standard lays down the inspection methods used to assess the print quality of bar code symbols.

It applies to print quality inspection for various types of bar code symbols.

II. Normative references

GB2828 Sampling procedures and tables for lot-by-lot inspection by attributes (for inspection of successive lots)

GB7705 Planographic decorative printed matter; GB12053 Alphanumeric character sets for optical recognition — Part: OCR-A character set — Shapes and dimensions of printed images

GB12508 Alphanumeric character sets for optical recognition — Part: OCR-B character set — Shapes and dimensions of printed images

GB12904 Universal product bar code

GB12905 General terminology for bar code systems — Bar code symbol terminology

GB12906 China standard book number (ISBN part) bar code

GB12907 Codabar

GB12908 Code 39 bar code

GB/T14257 Symbol positions for universal product bar codes

3.1 Void: a printing defect in the bars of a bar code symbol whose reflectance is close to that of the spaces.

3.2 Spot: a printing defect in the spaces or quiet zone of a bar code symbol whose reflectance is close to that of the bars.

3.3 Print thickness: the coating thickness difference between the bars and the spaces in a bar code symbol.

3.4 Magnification factor: the ratio of the length dimension of a bar code symbol to its standard dimension.

IV. Inspection items

4.2 Bar (space) reflectance and print contrast (PCS value)

4.3 Bar (space) dimensional deviation

4.4 Quiet zone dimension

4.6 Dimensions of digits and letters

4.7 Check character

4.8 Decoding accuracy

4.9 Magnification factor

4.10 Print thickness

4.11 Print position

V. Technical requirements

5.1.1 The surface of the bar code symbol should be clean, with no visible dirt, wrinkles, damage or perforation.

5.1.2 Digits, letters and special symbols in the bar code symbol must be printed completely and clearly, without ambiguity.

5.1.3 Bar code characters should show no obvious voids, spots or broken lines; bar edges must be neat and free from obvious bending or deformation.

5.1.4 The ink colour of bar code characters should be uniform, with no noticeable variation.

5.2 The technical requirements in clauses 4.2 to 4.11 must comply with the national bar code standard adopted for the sample.

VI. Inspection methods

6.1 Environmental requirements: the inspection room temperature should be 23±2℃ and relative humidity 50%±5%.

6.2 Sample handling

6.2.1 The sample should be flat, wrinkle-free and undeformed.

6.2.2 When bar code symbols on labels, label paper and packaging are inspected, sufficient fixing dimensions should be kept around the sample.

6.2.3 When bar code symbols on actual packaged goods are inspected, no sample handling is required.

6.3.1 Visual inspection: place the sample under a D65 standard light source with a colour temperature of 5500–6500K and perform a visual check in accordance with clause 5.1.

6.3.2 Instrumental inspection; 6.3.2.1 Measuring instruments: use a microscope and a grid eyepiece micrometer.

6.3.2.2 Measurement procedure

a. Using the microscope and grid eyepiece micrometer, magnify and divide the spot or void, then calculate its area from the number of grid squares it occupies.

b. Compare the area value obtained in step a with the area limit specified in the national bar code standard adopted for the sample.

6.4 Bar (space) reflectance

6.4.1 Measurement conditions: the measurement conditions must comply with the national bar code standard adopted for the sample under inspection.

6.4.2 Measuring instruments: the measuring instruments must meet

the requirements of clause 6.4.1.

6.4.3 Measurement procedure

6.4.3.1 Instrument calibration

6.4.3.2 Place a backing under the sample. The backing should be a spectrally non-selective diffuse reflecting material with a reflection density of 1.50 or higher.

6.4.3.3 Take five measurement positions evenly along the longitudinal direction of the bars, and measure the reflectance of each bar (space) one by one from the start character to the stop character. Repeat the procedure at each height position.

6.4.4 Data processing

6.4.4.1 At the same height position, take the highest reflectance among the bars and the lowest reflectance among the spaces as the bar (space) reflectance for that height.

6.4.4.2 At five different height positions, take the highest bar reflectance and the lowest space reflectance as the bar (space) reflectance of the bar code symbol.

6.5 Print contrast (PCS value)

Print contrast (PCS value) is calculated according to formula (1): PCS=(RL−RD)/RL, where RL is the reflectance of the spaces in the bar code and RD is the reflectance of the bars.

6.6 Bar (space) dimensional deviation

6.6.1 The measurement conditions are the same as those in clause 6.3.1.

6.6.2 Measuring instruments: a length measuring instrument with a smallest division of 0.01mm.

6.6.3 Measurement procedure: take five measurement positions evenly along the longitudinal direction of the bars, and measure each bar (space) dimension one by one from the start character to the stop character. Repeat the procedure at each height position.

6.6.4 Data processing; 6.6.4.1 At the same height, take the maximum value of the dimensional deviations of the bars (spaces) as the maximum and minimum values of the bar (space) dimensional deviation at that height.

6.6.4.2 Take the maximum and minimum values of the dimensional deviations of the bars (spaces) at five different height positions as the bar (space) dimensional deviation of the bar code symbol.

6.7 Quiet zone dimension

Under the light source specified in clause 6.3.1, measure with a steel rule with a smallest division of 0.5mm.

6.8 Bar height: the measurement method is the same as clause 6.7.

6.9 Dimensions of digits and letters: the measurement method is the same as clause 6.7.

6.10 Check character: verify according to the calculation method specified in the national bar code standard adopted for the sample.

6.11 Decoding accuracy: read the bar code symbol with bar code reading equipment and compare the result with the visually inspected characters.

6.12 Magnification factor: the measurement method for bar code length is the same as clause 6.7, and the magnification factor is calculated according to the definition in clause 3.4.

6.13 Print thickness: under the light source specified in clause 6.3.1, measure with a thickness gauge with a smallest division of 0.01mm or an instrument of equivalent accuracy.

6.14 Print position: perform visual inspection according to GB/T14257.

VII. Inspection report

The inspection report depends on the inspection content of the sample.

Sampling for this standard is carried out in accordance with GB2828.

This standard was proposed by the China Article Numbering Centre.

This standard is under the jurisdiction of the China Article Numbering Centre, which is also responsible for drafting it.

The principal drafters of this standard are Wu Hailian and Zhou Gang.

— This article is reprinted from China Packaging Network (pack.cn), original link: http://news.pack.cn/show-362273.html