First, product quality testing conditions
1. Observe the ambient color around the surface: N6-N8, C (0.3. If the wall and ground around the observation surface do not meet the above requirements, apply a baffle that meets the above requirements to enclose the sample or use environmental reflections. Light produces less than 100 lux of illumination at the viewing surface.
The background of the observation reflection should be N5-N7, C<0.3; for the occasion with high color matching, C<0.2.
2. Detect dust and clean working environment.
3, operating temperature requirements
Temperature is 23°C±5°C Relative humidity is 60+15(-10)%
4, lighting conditions
1 Observe the transmission sample
The light source is a simulated body of CIE standard illumination body D50 (a typical crucible with a correlated color temperature of 6504K, X=0.3457, Y=0.3586 on CIE1931), and the profile of the light source should not be seen on the observation surface or there is a sudden change in brightness. The uniformity of the brightness is ≥ 80%, and the color rendering index of the light source is Pa ≥ 90.
2 Observe the reflection sample
The light source is a CIE standard illumination body D65 (typical calorimetry with a correlated color temperature of 6504K, X=0.3127 on CIE1931, Y=0.3291). There should be no illuminance changes in the observation plane. The uniformity of illuminance is ≥ 80%, and the color rendering index of the light source is Ra ≥ 90.
5. Observers must be non-color blind and non-colored normal color vision observers.
Second, the observation method
1. The transmissive sample should be illuminated by inactive diffuse light from behind and viewed perpendicular to the surface of the sample. Observe that the sample should be placed in the middle of the lighting surface as much as possible, so that at least three sides have 50mm wide illuminated borders. When the total area of ​​the observed transmission sample is less than 70mm x 70mm, the width of the illuminated boundary should be reduced appropriately so that the boundary area does not exceed 4 times the area of ​​the sample, and many parts are covered with a gray opaque light blocking material.
2. When observing the reflection sample, the light source is perpendicular to the surface of the sample, and the angle of observation is at an angle of 45° with the normal to the surface of the sample. For observation conditions of 0°-45° illumination, see Figure 1. As an alternative observation condition, it is also possible to illuminate with a light source at an angle of 45[deg.] to the normal to the surface of the sample and observe the surface of the vertical sample, corresponding to a viewing condition of illumination of 45[deg.] to 0[deg.]. See Figure 2.
figure 1
Third, the use of measurement and control bar
1, measurement and control principle
figure 2
The increase in the area of ​​1 dot is proportional to the total length of the edge of the dot.
2 Use the same area of ​​the geometry as yin and yang to measure the shifting of control points.
3 When the pattern changes, the angle at the included angle changes significantly from the length of the arc, which plays an amplification role.
4 Measure the horizontal and vertical azimuth changes using a line of equal or unequal width.
5 Use equidistant concentric circles to measure changes in any position.
2, the use of conditions
The conditions for using the test strips are the same as the conditions for printing, proofing and printing.
3, use method
Long strips should be used and placed at the end of the sheet, parallel to the axis of the printing cylinder, in order to observe and control the uniformity of the image.
4, printing common control strip
1GATF star: Used to determine dot gain, slip, and ghost.
2GATF signal strip: used to determine dot gain and distortion.
3 Brunner signal strips: for density determination, dot gain, dot distortion.
4 high-profile network detection map: for the observation of high-profile network reproduction.
CY/T5-1999 fine print reproduction of 2% -4% dot area, the general print bright tone reproduction of 3% -5% dot area.
5GATF color signal strip: used to determine dot gain, distortion, density, and gray balance.
Fourth, the density measurement
1. Measuring principle of reflective density meter
The stable light source shines on the surface of the printed product through the lens focusing, and part of the light is absorbed. The absorption condition depends on the thickness of the ink layer. The unabsorbed light is reflected by the surface of the printing paper, and the lens collects and enters the irradiation light at a 45 degree angle. The reflected light is transmitted to the receiver; the receiver converts the received light amount into electricity, and the electronic system compares the measured current with a reference value (absolute white reflection amount), and calculates the measured ink layer according to the comparison value. Absorption characteristics. Measurement results are displayed on the screen in density units. (shown in Figure 3)
Figure 3 Measuring principle of reflective densitometer
2. Selection of color filter in density measurement
Table 1
Measured Color Filter Name Filter Code Filter Color
Y Koda Leiden 47B B Blue Violet
M Koda Leiden 58 G Green
C Kodak Redden 25 R Red
BK Koda Leiden 106 O Light Orange
The complementary color density of the second color ink is always used to measure the color density of the overlay.
3, must pay attention to the problem of the density test process
1 Test error of different densitometers
Although some of the domestic density meters are domestically produced, most of them are imported, and the sources of imported density meters are very broad, including those of Japan, the United States, and Italy. Different types of densitometers must have different measured data. For example, one densitometer adopts Leiden color filter, the other densitometer adopts interference filter, and the same sample is measured. The test results of the two are completely different. Therefore, in order to avoid the test error of different densitometers, it is better to use the same series of densitometers in the same unit. In addition, the density data provided by customers must also be converted according to the density meter used by the factory.
2 Densitometer calibration should be accurate
Density meters usually have high and low density calibrations before they are used. Only by setting the standard, the density data tested will be accurate. Density meter low density calibration mainly depends on the paper, because the whiteness of paper used in different countries is not the same, resulting in different densitometer low density calibration value of the difference. If there is 0.06, some 0.07 and so on. It is reasonable to say that the low-density calibration value is most reasonable based on the paper used, but it requires a zero point for each paper and the operation is too cumbersome. Therefore, in actual use, as long as it is the same density meter, it is calibrated according to the low density value of the test board. Although the absolute value is slightly wrong, it is relatively accurate instead. At the same time, high-density values ​​must also be calibrated. For example, the high density should be 2.0. If it is set to 1.8, the measured density is low. Contrary to 2.2, the measured density is high. In particular, the calibration of the two tests is not the same, and testing means it is obvious.
3 To change the color filter regularly for color testing, the color density of the color filters used by different density meters is not equal, and the balance between the color filters will be affected for a certain period of time. Therefore, regular replacement is required.
4 to test under stable conditions
The power supply must be stable, the operation must be serious, and there must be a certain settling time after starting up. The liner must be uniform when measuring. In the case of a printed sample with a picture, it should be lined with white paper for measurement. If there are pictures on both sides, lining paper is required for measurement. When actually measuring, several tests are repeated. The error with the density value within 1.0 is controlled at 0.01, and the error with the density value above 1.0 is controlled at 0.02. Exceeding the given range, the density meter should be checked and adjusted.
5 When measuring density, you must also pay attention to the difference between wet and dry measurements. Generally, the difference should be 5%-10%. If the dry density is used as a benchmark, the wet density should be properly high, ie, the wet dry density difference should be taken into consideration. Therefore, it is preferable that the time interval for measuring the density be fixed (the color reflection densitometer having a polarization optical device has no such problem). Normally the wet density must be measured within 30 seconds after printing, and the dry density is measured 30 minutes after printing. When measuring wet color density, it should be done at the same time interval.
6 The color density of printing inks with different hue cannot be compared. Reflection density measurement is not a color measurement. Only color inks with the same hue are meaningful to each other.
5, dark tone density control range (Table 2)
6, the same batch of products in the field density of the printed sheet allowable error:
Measured color fine prints Ds General prints Ds
Y 0.85-1.10 0.80-1.05
M 1.25-1.50 1.15-1.40
C 1.30-1.55 1.25-1.50
BK 1.40-1.70 1.20-1.50
C, M ≤ 0.15, BK ≤ 0.20, Y ≤ 0.10, the color is in line with the sample.
7. Offset Printing and Printing Requirements for Ink and Density
1 The printing frame is evenly colored. The word "used" is used as the standard, and the fine product density is 0.27-0.33. The general product density is 0.25-0.35. In the classical Chinese, the word “person†or the same stroke is used as the standard, and the density data is the same as the “sâ€.
2 field density. The printing ink color density measurement value of the printing sheet is 0.9-1.3.
Fifth, the other requirements of the quality of flat print
1, overprint
Multi-color version of the image outline and location should be accurately nested, fine product overprint allowable error ≤ 0.10mm; normal print overprint allowable error ≤ 0.20mm. Offset printing and overprinting requirements; printing book page layout is positive and negative overprinting accuracy, its overprint tolerance error fine product is less than 2mm, the general product is less than 3mm.
2, appearance
1 layout clean, no trace of dirt.
2 The color tone of printing plate should be basically the same, the allowable error of fine product size is <0.5mm, and the allowable error of general product size is <1.0mm.
3 The text is complete, clear, and accurate.
3, outlets
1 dot gain control range
The network is clear and the angles are accurate and there is no ghosting. The enlargement value range of fine print outlets is 10%-20%; the increase value of general print outlets ranges from 10%-25%.
2 network point increase value calculation method
The dot gain value refers to the difference between the dot area of ​​a part of the printed matter and the dot area of ​​the corresponding color separation sheet. The formula is as follows
Printed dot area
A(%)=100%×[1-10-(DT-DO)]/[1-10-(DS-DO)
1. Observe the ambient color around the surface: N6-N8, C (0.3. If the wall and ground around the observation surface do not meet the above requirements, apply a baffle that meets the above requirements to enclose the sample or use environmental reflections. Light produces less than 100 lux of illumination at the viewing surface.
The background of the observation reflection should be N5-N7, C<0.3; for the occasion with high color matching, C<0.2.
2. Detect dust and clean working environment.
3, operating temperature requirements
Temperature is 23°C±5°C Relative humidity is 60+15(-10)%
4, lighting conditions
1 Observe the transmission sample
The light source is a simulated body of CIE standard illumination body D50 (a typical crucible with a correlated color temperature of 6504K, X=0.3457, Y=0.3586 on CIE1931), and the profile of the light source should not be seen on the observation surface or there is a sudden change in brightness. The uniformity of the brightness is ≥ 80%, and the color rendering index of the light source is Pa ≥ 90.
2 Observe the reflection sample
The light source is a CIE standard illumination body D65 (typical calorimetry with a correlated color temperature of 6504K, X=0.3127 on CIE1931, Y=0.3291). There should be no illuminance changes in the observation plane. The uniformity of illuminance is ≥ 80%, and the color rendering index of the light source is Ra ≥ 90.
5. Observers must be non-color blind and non-colored normal color vision observers.
Second, the observation method
1. The transmissive sample should be illuminated by inactive diffuse light from behind and viewed perpendicular to the surface of the sample. Observe that the sample should be placed in the middle of the lighting surface as much as possible, so that at least three sides have 50mm wide illuminated borders. When the total area of ​​the observed transmission sample is less than 70mm x 70mm, the width of the illuminated boundary should be reduced appropriately so that the boundary area does not exceed 4 times the area of ​​the sample, and many parts are covered with a gray opaque light blocking material.
2. When observing the reflection sample, the light source is perpendicular to the surface of the sample, and the angle of observation is at an angle of 45° with the normal to the surface of the sample. For observation conditions of 0°-45° illumination, see Figure 1. As an alternative observation condition, it is also possible to illuminate with a light source at an angle of 45[deg.] to the normal to the surface of the sample and observe the surface of the vertical sample, corresponding to a viewing condition of illumination of 45[deg.] to 0[deg.]. See Figure 2.
figure 1
Third, the use of measurement and control bar
1, measurement and control principle
figure 2
The increase in the area of ​​1 dot is proportional to the total length of the edge of the dot.
2 Use the same area of ​​the geometry as yin and yang to measure the shifting of control points.
3 When the pattern changes, the angle at the included angle changes significantly from the length of the arc, which plays an amplification role.
4 Measure the horizontal and vertical azimuth changes using a line of equal or unequal width.
5 Use equidistant concentric circles to measure changes in any position.
2, the use of conditions
The conditions for using the test strips are the same as the conditions for printing, proofing and printing.
3, use method
Long strips should be used and placed at the end of the sheet, parallel to the axis of the printing cylinder, in order to observe and control the uniformity of the image.
4, printing common control strip
1GATF star: Used to determine dot gain, slip, and ghost.
2GATF signal strip: used to determine dot gain and distortion.
3 Brunner signal strips: for density determination, dot gain, dot distortion.
4 high-profile network detection map: for the observation of high-profile network reproduction.
CY/T5-1999 fine print reproduction of 2% -4% dot area, the general print bright tone reproduction of 3% -5% dot area.
5GATF color signal strip: used to determine dot gain, distortion, density, and gray balance.
Fourth, the density measurement
1. Measuring principle of reflective density meter
The stable light source shines on the surface of the printed product through the lens focusing, and part of the light is absorbed. The absorption condition depends on the thickness of the ink layer. The unabsorbed light is reflected by the surface of the printing paper, and the lens collects and enters the irradiation light at a 45 degree angle. The reflected light is transmitted to the receiver; the receiver converts the received light amount into electricity, and the electronic system compares the measured current with a reference value (absolute white reflection amount), and calculates the measured ink layer according to the comparison value. Absorption characteristics. Measurement results are displayed on the screen in density units. (shown in Figure 3)
Figure 3 Measuring principle of reflective densitometer
2. Selection of color filter in density measurement
Table 1
Measured Color Filter Name Filter Code Filter Color
Y Koda Leiden 47B B Blue Violet
M Koda Leiden 58 G Green
C Kodak Redden 25 R Red
BK Koda Leiden 106 O Light Orange
The complementary color density of the second color ink is always used to measure the color density of the overlay.
3, must pay attention to the problem of the density test process
1 Test error of different densitometers
Although some of the domestic density meters are domestically produced, most of them are imported, and the sources of imported density meters are very broad, including those of Japan, the United States, and Italy. Different types of densitometers must have different measured data. For example, one densitometer adopts Leiden color filter, the other densitometer adopts interference filter, and the same sample is measured. The test results of the two are completely different. Therefore, in order to avoid the test error of different densitometers, it is better to use the same series of densitometers in the same unit. In addition, the density data provided by customers must also be converted according to the density meter used by the factory.
2 Densitometer calibration should be accurate
Density meters usually have high and low density calibrations before they are used. Only by setting the standard, the density data tested will be accurate. Density meter low density calibration mainly depends on the paper, because the whiteness of paper used in different countries is not the same, resulting in different densitometer low density calibration value of the difference. If there is 0.06, some 0.07 and so on. It is reasonable to say that the low-density calibration value is most reasonable based on the paper used, but it requires a zero point for each paper and the operation is too cumbersome. Therefore, in actual use, as long as it is the same density meter, it is calibrated according to the low density value of the test board. Although the absolute value is slightly wrong, it is relatively accurate instead. At the same time, high-density values ​​must also be calibrated. For example, the high density should be 2.0. If it is set to 1.8, the measured density is low. Contrary to 2.2, the measured density is high. In particular, the calibration of the two tests is not the same, and testing means it is obvious.
3 To change the color filter regularly for color testing, the color density of the color filters used by different density meters is not equal, and the balance between the color filters will be affected for a certain period of time. Therefore, regular replacement is required.
4 to test under stable conditions
The power supply must be stable, the operation must be serious, and there must be a certain settling time after starting up. The liner must be uniform when measuring. In the case of a printed sample with a picture, it should be lined with white paper for measurement. If there are pictures on both sides, lining paper is required for measurement. When actually measuring, several tests are repeated. The error with the density value within 1.0 is controlled at 0.01, and the error with the density value above 1.0 is controlled at 0.02. Exceeding the given range, the density meter should be checked and adjusted.
5 When measuring density, you must also pay attention to the difference between wet and dry measurements. Generally, the difference should be 5%-10%. If the dry density is used as a benchmark, the wet density should be properly high, ie, the wet dry density difference should be taken into consideration. Therefore, it is preferable that the time interval for measuring the density be fixed (the color reflection densitometer having a polarization optical device has no such problem). Normally the wet density must be measured within 30 seconds after printing, and the dry density is measured 30 minutes after printing. When measuring wet color density, it should be done at the same time interval.
6 The color density of printing inks with different hue cannot be compared. Reflection density measurement is not a color measurement. Only color inks with the same hue are meaningful to each other.
5, dark tone density control range (Table 2)
6, the same batch of products in the field density of the printed sheet allowable error:
Measured color fine prints Ds General prints Ds
Y 0.85-1.10 0.80-1.05
M 1.25-1.50 1.15-1.40
C 1.30-1.55 1.25-1.50
BK 1.40-1.70 1.20-1.50
C, M ≤ 0.15, BK ≤ 0.20, Y ≤ 0.10, the color is in line with the sample.
7. Offset Printing and Printing Requirements for Ink and Density
1 The printing frame is evenly colored. The word "used" is used as the standard, and the fine product density is 0.27-0.33. The general product density is 0.25-0.35. In the classical Chinese, the word “person†or the same stroke is used as the standard, and the density data is the same as the “sâ€.
2 field density. The printing ink color density measurement value of the printing sheet is 0.9-1.3.
Fifth, the other requirements of the quality of flat print
1, overprint
Multi-color version of the image outline and location should be accurately nested, fine product overprint allowable error ≤ 0.10mm; normal print overprint allowable error ≤ 0.20mm. Offset printing and overprinting requirements; printing book page layout is positive and negative overprinting accuracy, its overprint tolerance error fine product is less than 2mm, the general product is less than 3mm.
2, appearance
1 layout clean, no trace of dirt.
2 The color tone of printing plate should be basically the same, the allowable error of fine product size is <0.5mm, and the allowable error of general product size is <1.0mm.
3 The text is complete, clear, and accurate.
3, outlets
1 dot gain control range
The network is clear and the angles are accurate and there is no ghosting. The enlargement value range of fine print outlets is 10%-20%; the increase value of general print outlets ranges from 10%-25%.
2 network point increase value calculation method
The dot gain value refers to the difference between the dot area of ​​a part of the printed matter and the dot area of ​​the corresponding color separation sheet. The formula is as follows
Printed dot area
A(%)=100%×[1-10-(DT-DO)]/[1-10-(DS-DO)
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