How to achieve perfect printing of QR code?
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The development of the Internet and the popularization of information technology have brought great convenience to people, especially the emergence of two-dimensional codes, which makes it easy for people to know the information contained in them by simply sweeping out the corresponding equipment. . QR codes can be seen everywhere on business cards, leaflets, newspapers, etc. The application of QR codes is becoming more and more widespread, and printing companies are also facing more and more QR code printing services. However, due to printing equipment, paper, ink, human operation and other reasons, the two-dimensional code often has deviations in the printing process, causing many problems for the printing enterprise. Here, the author will share with you how to perfectly print the QR code, I hope to help everyone.
Unknown knowledge of QR code
In order to achieve the perfect printing of the QR code, it is necessary to have a clear understanding of the QR code. This is also lacking in many printing operators.
1. Structure of the QR code
At present, the QR code used in the market is a QR code, and the structure of the QR code is introduced with the focus of the QR code. There are 40 specifications for QR codes. The specification of version X is (4X+17)×(4X+17), and Figure 1 shows the symbol structure of the QR code of version 7. Each QR code symbol consists of a nominal square module that forms a square array consisting of a coded area and functional graphics including position detection patterns, position detection pattern separators, positioning patterns, and correction patterns.
(1) Position detection pattern, position detection pattern separator: used for positioning of two-dimensional code. For each QR code, the position is fixed, but the size specifications will be different; these black and white spaced rectangular blocks It is easy to detect image processing.
(2) Correction pattern: The number of correction patterns varies depending on the size. The correction pattern is mainly used for the correction of the QR code shape, especially when the QR code is printed on an uneven surface, or distortion occurs when photographing.
(3) Positioning graphics: These small black and white grids are like coordinate axes, and a grid is defined on the QR code.
(4) Format information: indicates the error correction level of the QR code, which is divided into L, M, Q, and H.
(5) Data: The content is encoded in a binary grid of black and white. 8 grids can encode one byte.
(6) Version information: that is, the specification of the QR code, each version of the symbol is increased by 4 modules per side than the previous version.
(7) Error correction code word: used to correct the error caused by QR code damage.
2. Identification of two-dimensional code
Since objects of different colors have different wavelengths of visible light, white objects can reflect visible light of various wavelengths, and black objects can absorb visible light of various wavelengths. Therefore, the automatic recognition of the two-dimensional code is realized by utilizing the technical characteristics of the light reflection difference of the color in the two-dimensional code symbol.
The recognition process is: light source illumination → illumination onto the surface of the two-dimensional code symbol → light reflection → photoelectric converter receiving and photoelectric conversion to generate analog electrical signal → analog electrical signal is amplified, filtered, shaped, and formed into a square wave signal → decoder translation Code → digital signal.
When identifying, the first reading rate is generally above 85%, the bit error rate is less than 0.01%, and the rejection rate is less than 1%. Among them, the first reading rate = (the first reading the number of two-dimensional code symbols / the total number of reading two-dimensional code symbols) × 100%; error rate = (number of error recognition / total number of error recognition) × 100%; rejected The recognition rate = (the number of two-dimensional code symbols that cannot be recognized / the total number of two-dimensional code symbols) × 100%. For some important occasions, the first reading rate is required to be 100%.
QR code design
A good two-dimensional code design is the premise of perfect printing of two-dimensional code. In the design process, it is necessary to comprehensively consider the characteristics of the two-dimensional code and the printability.
1. Size and resolution settings
The minimum area of the QR code is 19mm × 19mm, and can not have shading, mottled color, the recommended resolution is best set to 150 ~ 300dpi, otherwise the size of the QR code is too small, too dense or insufficient resolution, may cause the printed QR code can not be scanned normally . When the two-dimensional code is a shaped two-dimensional code, the corresponding two-dimensional code size requirement refers to the true two-dimensional code size.
2. Color matching
The color matching has a large influence on the maximum reflectance of the strip and the print contrast. The principle of maximizing contrast and meeting the requirements of standards are important principles to be mastered in the design and printing of QR codes. Black and white is the best choice. As long as there is enough contrast between the strip and the space, other colors can be used, but the strips cannot be yellow, orange, red, dark brown or gold. If the foreground color and foreground color of the QR code after the beautification is too close, the QR code cannot be scanned normally. In actual production, for the combination that is difficult to grasp, it is necessary to perform proofing in advance, and after the test has no problem, it can be mass-produced.
3. Generation of QR code
The information contained in the QR code is too long, which makes the generated QR code pattern too complicated and cannot be recognized. If there is more information, it is recommended to use the live code function of the forage web to generate the QR code.
4. Leave the blank area size
The blank area plays the role of the two-dimensional code recognition device in preparing for scanning, and it must be ensured that the size is sufficient. In the process of scanning and reading the actual two-dimensional code, in order to avoid the interference of surrounding colors, the width of the left and right blank areas of the two-dimensional code should generally be not less than 5 mm.