Three main points of the printing technology of newspaper two-dimensional code

1. Color contrast and register

The two-dimensional code can be monochromatic black or multi-color overprint. The factors that affect the printing quality of two-dimensional codes mainly include color contrast and overprint errors.

(1) Color contrast

Inadequate color contrast of newspaper QR codes will affect the recognition of QR codes by mobile phone software. Bar code printing symbol optical characteristics requirements: in order to read reliably, after printing, the line and space in the bar code should have a clear contrast, the empty reflectivity should be as large as possible, and the line reflectivity should be as small as possible. The domestic newsprint according to the national standard, the whiteness is more than 50%, normal printing can meet the recognition requirements of the two-dimensional code. However, it should be noted that when creating a QR code on a newspaper, the editor should be reminded that shading cannot be added to prevent situations where the contrast is insufficient to affect reading.

(2) Overprint error

Mainly refers to the color QR code. When printing, the QR code must be neat and clear. Generally, we stipulate that the maximum value of overprint error (overprint error of main color and picture) should be less than or equal to 0.4 times the nominal width of the narrowest line barcode. The author sampled some black two-dimensional codes with overprinted four-color overprints to verify their reading results. The results are shown in Table 1. According to the national standard, the overprint error of newspapers is required to be less than or equal to 0.3mm. In fact, some newspapers at the provincial level and above with more advanced printing equipment and higher quality requirements can fully meet the standards in this regard. Some local newspapers, such as overprinting is not stable, it is recommended that the QR code be printed in monochrome, so that there is no overprinting problem.

2. Printing missing some elements

When printing, please pay attention to the loss of elements on the printing plate, so as not to cause difficulty in reading the QR code. In printing, due to the printing plate or blanket, it is easy to cause the printed pattern to be damaged. For the slightly "fragmented" pattern of the QR code, special attention should be paid to the pre-press plate making and post-check.

3. Printing ink color problem

To control the size error of the two-dimensional code symbol, the key is to control the ink color and printing pressure in printing to ensure the accurate restoration of the two-dimensional code stripes. Under normal conditions, we must ensure that "water is small and ink is small" when discharging ink, and at the same time ensure the necessary thickness of the ink layer. No streaks due to low pressure or insufficient ink color appear; no streaks due to excessive pressure or large ink appear.

The above are some common problems that appear in printed QR codes, and are actually the subject of our daily quality management. I hope that the above experience can provide a reference for the quality management of the two-dimensional code printing in the newspaper printing house.