Signal bar: Mainly used for human visual evaluation prints, with relatively simple functions and direct expression of the appearance quality information of prints. Such as the United States Printing Foundation invented GATF star, GATF digital signal, color signal and so on.
Test strip: A multi-function marker element mainly based on densitometer detection and evaluation, usually a combination of visual identification and densitometer test, and a test strip for numerical calculation with the help of graphs and curves. Such as Bruner test strip.
Control bar: It is a multifunctional control tool that combines visual evaluation and test evaluation of signal strips and test strips. Such as: Bruner third generation test strip.
First, the formation of outlet expansion According to the state of the expansion of the network classification 1, linear expansion: refers to the printing outlets have a direction to expand the edge, originally printing outlets are now square, prismatic, round, chain-shaped, linear expansion is that outlets toward One direction expands linearly.
2, the expansion of the area:
The printed dots expand around, and the dot area enlarges, which is generally proportional to the length of the edge of the dot. In other words, the dot area is large, and the length of the edge of the dot also increases at this time.
3, increase the density:
The increase in density is proportional to the area of ​​the printing dot, the density increases, the ink is large, the ink is large, and the dot area is large.
In accordance with the changes in the printing outlets classification 1, normal expansion. This kind of printing dot enlargement is allowed, that is to say, the dots expand normally, the density of the center position is high, and the density of edge positions is low.
2, ghosting outlets. This kind of printing dot enlargement is not allowed, and dot ghosting occurs during printing, which seriously affects the dot color effect.
3, there is no regular network expansion. When there are no regular dot gains, there is no rule in the printed dots. The dots will be expanded around. This will easily result in stencils and dirty prints, which will affect the quality of the printed products. This ruleless dot gain is not allowed. . The network expansion scope does not exceed 15%, 12%, and 10%.
Second, the relationship between the number of lines and the length of the edge of the network As the network changes occur in the surrounding parts of the printing network, the more the number of network points per unit area, the more the surrounding parts of the network points, and thus the amount of change in the network points will also increase. Large, it can be seen that the network expansion of thin network lines is larger, and the expansion of corresponding thick network lines is smaller.
Printed outlets are classified into coarse or fine outlets depending on the use of non-wind, and fine-printing products for close-range viewing must use fine outlets such as periodicals, pictorials, and trademarks. Long-distance viewing of fine print products uses coarse dots, such as large-scale posters and posters. The dots are in inches. That is, within a one-inch area, the common cable has 60 lines/inch, 90 lines/inch, 133 lines/inch, 150 lines/inch, and 175 lines/inch.
For example, the dot area is also 60%, the blank area is 40%, one is 60 lines/inch, one is 175 lines/inch, and the 175 line/inch dot expansion will be much larger than 60 lines/inch. This shows that the 175 lines/inch fine line has a long edge length, so the dot enlargement is larger. The length of the 60-line/inch coarse cable edge is short, so the dot expansion is smaller.
Third, the signal bar control network expansion GATF digital signal bar GATF digital information bar is made of 27 lines / cm thick dot for the substrate, the middle inlaid with 80 lines / cm flat network laid 0-9 number, in the original signal The density of the digital 2 in the bar is the same as the background density.
Specific use is as follows:
1. The GATF digital signal bar assumes that the coarse net does not change and the dot does not expand. Observe the difference in density between the digits and the ground color with the naked eye.
2. On the original version, the area of ​​1-7 digital dots will be offset by 3%-5% in turn, and 7-9 will be decremented by 5% or more. The area of ​​0th dot is the largest, and the area of ​​9th dot is the smallest.
3. Since it is assumed that the coarse wire does not expand at all, the dot gain is determined based on the same digital and background density.
Example 1: Digital 5 has the same background density. At this time, from the beginning of data 2, the digital transfer has three levels of printing dots (a reference with 2 as the fixed dot does not expand, and the transfer is reduced by 3%-5% for 3 levels). Digital 5 has expanded its network by 9%-15%.
Example 2: The number of GATF signal bars is 1, which is the same as the background color density. Digital 2 is used as a reference and the transfer is made in one stage. The dot size is reduced by 3%-5%.
Using data 2 as a reference, 2 used to be a narrowing of outlets, followed by an expansion of outlets.
The scale's dot control emits 36 black and white wedge lines of equal width outward from the center of the circle, with a small degree of whiteness at the center of the circle.
Stars are based on the size of the central white point to determine the size of the dot expansion.
The central white spot is large, indicating that the dot expansion is small.
The central white spot is small, indicating that the outlets have been enlarged.
The star mark is suitable for a test point expansion test tool, and its role is to be able to identify the type of dot gain.
1. The white spots at the center of the star become elliptical, indicating that the outlets have directional expansion. When the center white dot of the star sign shows "→0 ←", this type of ellipse indicates that the net point is expanded to the left and right, which is called horizontal expansion; the dot network shows that the "O" is called an up and down expansion network. Or called vertical expansion.
2, if the center of the star appears ghosting, the middle of the white point, not only smaller, but also appears "8" or "∞" shape, indicating the network ghost, paste version.
In summary, the feature of the GATF data signal strip is that it can provide a data. Dot gains give a quantitative amount, and stars can identify the types of dot gains. Both have their own uses and benefits, and they can be used to complement each other.
Fourth, the test strip control network expansion In the printing and printing process, the test strip to control the expansion of the printing outlets, the Bruner test strip, respectively, the use of the most widely used.
The composition of the Bruner test strip:
50% 50% 75% 75% Fine Thickness

Fine: Indicates a fine dot: Indicates that the bold dot Brunner test strip is unchanged from the thick line dot and does not expand as a reference.
The calculation of outlet expansion is based on the comparison segment with the coarse network cable as a reference. The coarse and fine mesh of the Bruner test strip are respectively 30 lines/inch and 150 lines/inch. Therefore, the 30-line/inch coarse network segment is ignored and the 30-line/inch coarse network is not expanded.
2, using the density and dot area of ​​the characteristic curve according to DR = tg1/1-a
a=1-10-DR
The density value is equal to the area difference.
In the Bruner test strip test, the density meter was used to measure the coarse mesh first, then the fine mesh was measured, and then the fine mesh-rough mesh = dot gain value was used.
Brunner's calculation methods for dot gain 1. Select 50% of test points for dot gain = (fine net density - coarse net density) × 100% = D fine (where D represents density)
2. Select 75% of test strips to expand = (fine net density - coarse net density)/2×100%
The advantage of the Bruner method for calculating the dot gain is that the Bruner test strip is easy to calculate.
2, can eliminate the test error. If there is an absolute density error during the test. There are absolute errors in testing fine and coarse dots.
Dot enlargement = (D fine - coarse) × 100%
3. Since the coarse and fine nets are measured at the same place and at the same time, the drying conditions of the inks are the same and the inks are less affected by the printing inks, and thus have nothing to do with the wet and dry ink.
The Brunner test strip method is used to calculate the disadvantages of dot gain. There is an absolute error. It uses a=1-10-DR
This formula assumes that the ink is completely absorbed on the paper, and the paper is totally reflected. However, in the actual printing process, it is absolutely impossible for 100% of the ink to be fully absorbed. The whiteness of the paper is different, and 100% of total reflection is impossible.
When the dot gain (50%) = (fine net - coarse net)/Dr × 100%, the Bruner test strip cannot be tested at this time.
2, there are some limitations.
50% (0.3-0.5) over this range will not work.
75%, (0.6-0.8) outlets expanded by more than 15% will not be calculated.
Choice of test points 1. Test points should be arranged as far as possible at the largest point of the network expansion (50% outlets).
2, try not to choose the test point in the outlets and outlets at the corner. Because the corner is unstable. Corners at outlets will change.
The principle of selection of test points 1, the middle tone: such as the character's skin color and face parts, subtle levels of rich, quality requirements of the original manuscript, you can use 40% and 50% of the test points.
2, for the average general product, you can use 75% of the test points.
The error of the test point 1, the current use is generally a copy of the Bruner test strip, there is a copy error.
2, the test strip is generally used in a single color, so there is a color overlay error.
In addition, the first generation, second generation, and third generation Bruner test strips are widely used by various printing manufacturers. The third generation Bruner printed test control strip, which was developed in 1984 and is divided into 7 segments, can be used according to the required size. The contents of the control strip test include: color standard: 25% - 75% of the segment; Bruner's three-segment field, 50%, special micro-measurement segment; neutral ash reduction segment; printing degree reduction segment; printing plate resolution segment; Four-color three-section test section.
The following test functions are used to determine the density of the ink layer, to monitor the enlargement of network points, to check the distortion and ghosting of dots at the time of printing, to determine whether the resolution of the printing plate and the exposure amount are accurate, and to control the specific changes in the depth of the printing when printing, proofing, or printing; The area of ​​the network is evenly connected to the area of ​​different areas; the control of printing fine dots; gray balance detection; detection of overprint percentage; detection of three-color Y, M, C reduction of black density and hue; detection of monochrome ink printing density.
In actual production, the test strips are widely used in the printing, proofing, printing, and mechanical debugging of the plate making.
Fifth, Bruner test control strip detection items 1, image clarity; 2, printing overprint is accurate; 3, print contrast control; 4, print tone reproduction; 5, printing ink color reproduction; 6, detection Failure of machinery and equipment; 7. Detection and evaluation of ghosting; 8. Expanded scope and types of outlets. (Wang Xincheng) ("China Packaging News")

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