Barcode printing process in detail (a)

Barcode technology has been developed over 50 years ago. It has the advantages of rapidity, accuracy, reliability, and low cost. It has now become one of the important information technologies in the modern society, and it has played a huge role in the field of commodity circulation. . In recent years, most of the businesses contracted by packaging and printing companies require the printing of barcodes, such as food, beverages, tobacco, alcohol, daily chemical detergents, books, medicines, and textiles. The printing of bar codes involves multiple links, each of which directly affects the quality and readability of bar codes, and therefore must be noticed. Here are some of the issues that should be noted in the bar code printing process.

First, the bar code reading principle

A bar code is a mark consisting of a set of regularly arranged bars, spaces, and corresponding characters. “Bar” refers to the part where the reflectance of light is low, and “empty” refers to the part where the reflectance of light is high. The data expresses certain information, and it can also be read and imported by a specific scanning device.

The bar code is read by light shining on the strips and the space, and producing different reflectivity (that is, the contrast of the empty space). Here we need to briefly introduce the Bar Code Print Contrast (PCS).

First of all, conceptually speaking, Print Contrast Signal (PCS) refers to the ratio of the difference between the reflectivity of the bar code and the reflectance of the bar, which is one of the optical indicators of the bar code symbol. Barcode PCS is calculated as follows:

PCS=(RL-RD)/RL×100%

Among them, RL is the empty reflectivity, RD is the reflectivity of the bar. The lower the reflectance RL of the bar, the better, and the higher the empty reflectance RD, the better. The larger the PCS value of the bar code, the better the optical properties of the bar code and the higher the reading rate. In general, when the PCS value of the bar code is in the range of 67% to 98%, it can be correctly read by the bar code scanning device.

Second, the basic quality requirements of bar codes

First of all, from the appearance point of view, the bar code surface is neat and clean, with no obvious dirt, wrinkles, or damage; the ink is uniform and there is no obvious deinking, stain, or broken lines; the edges of the bar are neat, and there is no obvious bending deformation; numbers, letters, The special symbols are printed completely and clearly.

Secondly, various quality indicators such as PCS values, symbol defects, bar code symbol size errors, printing tolerances, edge roughness, and ink layer thickness of bar codes have been specified in many national standards and are not detailed here. .

Third, the bar code design process should pay attention to the problem

1. Barcode color matching

According to the principle of barcode reading, there are certain principles for the color selection of barcodes. When designing a bar code, it is necessary to consider the reflectance of the bar and the space, and to increase the print contrast (PCS value) of the bar code space and bar as much as possible to ensure the recognizability and readability of the bar code.

According to the principle of optics, the reflectance of light varies with different colors. In general, light colors reflect light with high reflectivity, while dark colors have relatively low reflectivity (most of them are absorbed). Therefore, light colors such as white, yellow, orange, and red may be considered as empty colors for bar codes, and dark colors such as black, blue, brown, and green may be used as bar colors for bar codes. Since black does not reflect visible light of various wavelengths, and white can reflect light of all wavelengths, the black-and-white bar code is the easiest to read. However, it is worth noting that since most of the bar code scanning devices use red light sources with wavelengths of 630 to 700 μm, the use of red as the barcode bar should be avoided when designing bar codes.

The following table lists the bar code strips and their empty color combinations and their availability. They can be used as a reference when designing bar codes.

When the color of the barcode collides with the background color of the pattern, the background color may be hollowed out first, and then the barcode may be printed. Otherwise, the contrast of the stripe and the empty color is too small, and the scanner may not be able to read the barcode. For example, it is not possible to print barcodes directly on dark blue, dark green, or dark brown backgrounds. The background color underneath the barcode should be hollowed out and a white background (or white first printed) should be used to print the barcode. You can guarantee the readability of the barcode.

In addition, if the printed materials department uses aluminum-plated paper, aluminized film, gold-silver cardboard, or transparent plastic film, it is usually on the surface of the substrate with a white ink, and then a bar code (that is, anti-white). print).

2. The size of the barcode

The bar code printing size depends on the size of the bar code on the printed label or package and the specific printing conditions. The bar code is unique. Therefore, in the production and printing of bar codes, the proportion of bar codes cannot be arbitrarily changed or reduced. As long as the conditions permit, the standard size (original size) of bar codes should be used as much as possible. If you want to enlarge or reduce the bar code, the zoom ratio is generally controlled between 80% and 200%. Moreover, the bar width of the bar code should be appropriately modified while scaling the bar code. In the actual production process, you may encounter some small packaging product design (such as cigarette labels), if there is not enough place for bar code, you can properly cut the height of the bar code, but the required height of not less than the original height of 2 / 3.

Table 1 Colors of Barcodes