Key points of the QR code printing process
Due to the defects of printing equipment, printing plates, inks, human operations, etc., the QR code will be biased when printing. It is precisely because the QR code may have poor quality during the printing process, so before use, we should detect the QR code in advance, otherwise the QR code cannot be read, which will affect the customer's trust in the product. In the actual production of QR code printing, the following issues need special attention
Color contrast and registration
QR codes can be monochrome black or multi-color overprinted. The main factors that affect the printing quality of QR codes are color contrast and overprint error.
Color contrast
The insufficient color contrast of the newspaper QR code will affect the recognition of the QR code by the mobile phone software. The optical characteristics of the barcode printing symbol requirements: in order to read reliably, after printing, the line and the empty in the barcode should have obvious contrast, the reflectivity of the empty should be as large as possible, and the reflectivity of the line should be as small as possible. According to the national standard, the whiteness of domestic newsprint is more than 50%, and normal printing can meet the identification requirements of two-dimensional code. However, it should be noted that when making a QR code on a newspaper, it is necessary to remind the editor not to add shading to prevent the lack of contrast to affect the reading.
2. Overprint error
Mainly refers to color QR codes. When printing, the QR code must be neat and clear. In general, we specify that the maximum value of the overprint error (the overprint error of the main color and the image) should be less than or equal to 0.4 times the nominal width of the narrowest line code.
According to the national standard, the overprint error of the newspaper is required to be less than or equal to 0.3mm. As a matter of fact, some newspapers at or above the provincial level with relatively advanced printing equipment and relatively high quality requirements can fully meet the standards in this regard. Some local newspapers, such as overprinting is not very stable, it is recommended that the QR code be printed in monochrome, so that there is no overprinting problem.
3. Printing is missing part of the element
When printing, it is necessary to pay attention to the fact that the elements cannot be lost on the printing plate, so as not to make it difficult to read the QR code. In printing, due to the printing plate or blanket, it is easy to lead to the defect of the printing pattern, for the two-dimensional code, a slightly "fragmented" pattern, special attention should be paid to the pre-press plate making and post-inspection.
4. Printing ink color problem
To control the size error of the QR code symbol, the key is to control the ink color and printing pressure in printing to ensure that the QR code stripes are accurately restored. Under normal conditions, we need to ensure that the ink is "small in water" and in the necessary thickness of the ink layer. There are no streaks caused by low pressure or insufficient ink color; There is no spreading of streaks caused by excessive pressure or large ink.