Key points of QR code print in book printing process
Key points of QR code print in book printing process
Due to the defects of printing equipment, printing plate, ink and manual operation, there will be deviation in the book printing of QR code. It is precisely because the QR code may have poor quality in the printing process, so we should detect the QR code before use, otherwise we can't read the QR code, which will affect customers' trust in the product. In the actual production of QR code printing, the following problems need special attention.
Color contrast and registration
The QR code can be monochrome black or multi-color overprint. The main factors affecting the printing quality of QR code are color contrast and overprint error.
Color contrast
Insufficient color contrast of newspaper QR code will affect the recognition of QR code by mobile phone software. Requirements for optical characteristics of bar code printing symbols: in order to read reliably, there shall be obvious contrast between lines and spaces in bar code after printing, and the reflectivity of spaces shall be as large as possible, while the reflectivity of lines shall be as small as possible. According to the national standard, the whiteness of domestic newsprint is more than 50%, and the normal printing can meet the recognition requirements of QR code. However, it should be noted that when making QR codes in newspapers, editors should be reminded not to add shading to prevent insufficient contrast from affecting reading.
2. Overprint error
It mainly refers to color QR code. The QR code must be neat and clear during book printing. Generally, we specify that the maximum overprint error (overprint error between main tone and picture) should be less than or equal to 0.4 times the nominal width of the narrowest bar code.
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 above the provincial level with advanced printing equipment and high quality requirements can fully meet the standards in this regard. For some local newspapers with unstable overprint, it is recommended to use monochrome printing for QR code, so that there is no overprint problem.
3. Some elements lost in printing
When printing, pay attention not to lose elements 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 cause printing pattern defects. For the slightly "fragmented" pattern of QR code, special attention should be paid to pre printing plate making and post inspection.
4. Printing ink problem
To control the dimensional error of QR code symbols, the key in printing is to control the ink color and book printing pressure to ensure the accurate restoration of QR code stripes. Under normal conditions, we should ensure that the ink is "small in water and small in ink", and ensure the necessary ink layer thickness. No fringes caused by low pressure or insufficient ink color; There is no fringe diffusion caused by high pressure or large ink.
