Special Screen Printing - Barcode Printing

With the improvement of technology and development of signage technology, the use of special printing to deal with the bottom layer of signage panels has become a common means, and colorful, beautiful and moving, not only increased the decorative nature, but also obtained more prominent results. The following will introduce several common special screen printing technology and issues to pay attention to.

Fourth, bar code printing

The bar code is composed of a certain length, width and width of lines and numbers. It is a computer graphics language that is printed by ordinary printing methods and read by a photoelectric scanning reading device. Bar code is a kind of data input technology and automatic identification technology researched and developed in recent decades. It can reflect many kinds of information such as the category, manufacturer, weight, amount, date of manufacture, and circulation time of goods.

The bar code has a one-dimensional bar code and a two-dimensional bar code. Bar code code system more, such as one-dimensional bar code UPC code, EAN code, 39 code, ISBN code. The two-dimensional bar code is developed for the shortcomings of one-dimensional bar code information with small capacity and the ability to reduce the bar code area and improve resistance to pollution. It differs from the one-dimensional bar code in that text data can also be bar coded, and its data can be applied not only In English, numbers, Chinese characters, symbols, fonts and even blanks can also be handled, information storage up to 1100 numbers (one-dimensional bar code only 15 numbers). In addition, two-dimensional bar code can also use encryption technology to greatly improve the anti-counterfeiting performance of goods.

In addition to regular barcodes, there are some new types of barcodes, such as:

(1) Invisible bar code. Stealth barcodes mainly include cover-type invisible bar codes, photochemically processed invisible bar codes, and invisible ink-printed invisible bar codes.

(2) Watermark magnetic code. The watermark magnetic code is a binary interval created by the computer after the wet magnetic coating is produced. It is retained in the magnetic oxide after drying, resulting in a unique unchangeable 12-digit number, plus a special magnetic head. Watermark magnetic verification track for reading. The watermark magnetic code can be combined with a hologram to form a holographic magnetic strip anti-counterfeiting technology, so as to form a better anti-counterfeiting effect.

(3) Metal barcodes. Compared with ordinary bar code, it has the features of no fear of stains, strong anti-aging ability, and can also be made into invisible bar code. There are also new two-dimensional metal bar codes.

Barcodes can be printed in various ways such as offset printing, letterpress printing, gravure printing, screen printing, and non-printing (ink-jet printing). No matter which method is used for printing, the printing quality is required to be good. To sum up, there are mainly the following aspects:

(1) In order to ensure correct scanning and reading, the printed bar code shall be neat and legible, and the symbol shall be indistinguishable (defective point). The blank symbol shall have no residual black spots (blotches). Usually the maximum diameter of the flaws and stains shall be ≤ the narrowest bar code. 0.4 times the nominal.

(2) Controlling the size error of the barcode is to improve the read-first rate of the reading device and reduce the decoding error rate. This will not only improve the quality requirements for plate making, printing or printing, but also increase the tolerance requirements for reading devices.

(3) In order to read reliably, the bars and spaces in the bar code after printing should have obvious contrast signals. The larger the contrast signal of the bar code, the better the reading performance.

(4) Printing tolerance must be strictly controlled when printing, otherwise it will affect the reading effect.

(5) There is a certain requirement for the edge roughness of the barcode. When the roughness is too large, it cannot be read.

(6) The bar thickness and the empty ink layer thickness should generally be controlled within 0.1mm. Otherwise, the correctness of the reading will be affected by the different scanning planes between bars and spaces.

In order to ensure the quality of barcode printing, there are also certain technical and material requirements for the printing process, which mainly include:

(1) Size scaling. The bar code is usually the direct printing of the original, and the zooming is preferably done by a mechanism providing a bar code film.

(2) Color matching. Black ink is a safe bar code color, and white ink is the safest blank color. When choosing other colors to print bar codes, it is necessary to select the appropriate color combination according to the red effect of the color.

(3) Requirements for substrates. In terms of optical properties, substrates are required to have good light dispersion characteristics without specular reflection. For material dimensional stability, materials with good weatherability, dimensional stability after stress, good colorability, moderate ink spread, low permeability, moderate smoothness, and good finish should be used.

(4) The requirements for the ink. Consider the color shift of the ink when it comes to ink color matching. Since bar code printing is field printing, the reflection density that can be achieved by printing is related to the optical characteristics of the ink and the thickness of the ink layer. In the printing process, the reflection density of the printing ink increases with the increase of the ink thickness, when the ink thickness reaches a certain level. After the value, the density is saturated, so pay attention to the ink concentration and the thickness of the ink layer. In addition, we must pay attention to the viscosity of the ink can not be too low, the printing ink supply, pressure can not be too large, because these will affect the accuracy of bar code printing.


Source: Screen Printing Industry 2005.8 Qi Cheng