JP2003011327A - Printing color tone managing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing color tone measuring apparatus capable of rapidly regulating a color tone by simply measuring a deviation of the color tone of a printed matter during printing and obtaining a suitable ink regulating content. SOLUTION: A printing color tone managing apparatus comprises a spectrocolorimetric head capable of multi-split measuring in a running direction, a traversing unit for moving the spectrocolorimetric head, a white calibrating unit for white calibrating the head, an arithmetic unit for calculating a reflectivity of the printed matter based on detection data of a reflected light received by a photodetecting means of the head, and a data processing unit. The processing unit detects measured data for deciding a color tone change from the reflectivity calculated by the arithmetic unit. When the color tone is changed, the processing unit calculates a control amount to an inking content regulating mechanism of a printer so as to control the color tone change, and controls the inking content regulating mechanism of the printer based on the calculated control amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects color tone variation of a pattern on a printing paper on which the same pattern is repeatedly printed, and if there is variation, adjusts the color tone to prevent defective printed matter from occurring. The present invention relates to a print color tone measuring device.

[0002]

2. Description of the Related Art In a printing process in which inks of respective colors are superposed on a sheet of paper and a pattern is continuously reproduced, a large number of prints are arranged in a width direction of a printing machine (a direction orthogonal to a flow direction of printed matter). Equipped with a mechanism for adjusting the amount of ink called the ink key of, to obtain the desired color tone reproduction, in principle, if the state of the ink key is maintained constant,
The color tone should be stable, but changes in the printing machine condition,
The color tone of the printed matter gradually changes due to environmental changes such as temperature and humidity. Therefore, the color tone of the proof print and the main print are matched at the start of printing, or the characteristics of the printing machine change due to the state change, temperature change, humidity change, etc. during printing, and the color tone change due to the change of material physical properties (mainly ink). Need to be fixed.

Conventionally, the color tone of the finished printed matter is always monitored visually by the printing operator, and the deviation from the color tone of the reference printed matter determined at the time of printing is detected. When a change in color tone is detected, the color tone is adjusted by adjusting the opening degree of the ink key.

As described above, in the past, it was dependent on the intuition of a skilled operator to judge the difference in color tone from the reference printed matter by looking at the printed matter to be measured. Therefore, the subjectivity of the workers has a strong influence, and there are variations in the judgment between workers, and it is not possible to guarantee the objective quality (color tone of the printed matter). At the same time, secure skilled workers, maintain and improve the skill level. It has the drawback of being very expensive and time consuming.

Further, since the printed matter is running at high speed in the printing machine, it is difficult to check the color tone by looking at the running printed matter. Usually, the printed matter is appropriately extracted every plural sheets to change the color tone. Are watching. Therefore, there is a drawback that a large amount of defective printed matter is generated between the time when the operator detects the poor color tone and the time when the adjustment is completed.

Instead of the above-mentioned visual inspection of the operator,
It is considered to objectively detect a color tone change using a sensor. That is, a single color patch for color tone inspection is printed in the margin of the design of the printed matter, the color patch of the running printed matter is measured using a sensor such as a densitometer or a spectrocolorimeter, and online. It is considered to measure the variation in color tone.

However, in order to print a color patch, a blank space for inserting the color patch is necessary and the blank space portion is wasted. Moreover, since the color patch is a single color or a specific overprinted color, a color other than the patch color is used. Since the halftone part (multicolor overprint) cannot be measured, there is a drawback that the color cannot be guaranteed perfectly. Further, even in this case, it is still necessary to rely on the intuition of a skilled worker to determine the adjustment amount of the ink amount based on the measurement result.

[0008]

As described above, in the conventional printing work, it is necessary to secure a skilled worker who can visually judge the deviation of the color tone and to maintain and improve the skill level. It was In addition, when a color tone deviation occurs, it is necessary to adjust the ink amount after the defective printed material occurs, because the color tone deviation is detected by a sampling inspection of the finished product, and a large amount of color defects occur during that time. There was a drawback that printed matter was generated.

The present invention is a printing color tone measuring device capable of quickly adjusting a color tone by simply measuring a color tone deviation of a printed matter during printing and obtaining an appropriate ink adjustment amount without requiring skill and sampling inspection. The purpose is to provide.

[0010]

A printing color tone management apparatus according to the present invention according to the present invention, which has been made to achieve the above object, comprises a light irradiating means and a light receiving means, and is provided on the surface of a running printed matter. A spectral colorimetric head capable of repeatedly performing multi-division measurement in the traveling direction, a traverse device capable of moving the spectral colorimetric head in a direction parallel to the surface of a printed matter, and white calibration of the spectral colorimetric head At this time, a white calibration plate is provided with a mechanism for moving at least one of the spectral colorimetric head and the white calibration plate so that the white calibration plate is arranged on the front side of the measuring section of the spectral colorimetric head. An apparatus, an arithmetic unit for calculating the reflectance of the printed matter based on the detection data of the reflected light received by the light receiving means of the spectral colorimetric head, and a data processing unit. In the device The measurement data for determining the color tone fluctuation is detected from the reflectance data that is output, and if it is determined that the color tone is fluctuating, the inking amount adjustment mechanism of the printing machine is used to control the color tone fluctuation. The print color tone management device is characterized by calculating a control amount for the printing color tone and controlling the inking amount adjusting mechanism of the printing machine based on the calculated control amount. Here, the surface of the printed matter that is running is
It refers to the surface of the printing paper on which the pattern is printed on the printing machine.

The present invention according to claim 2 is a measurement control for controlling a measurement by using an output signal from at least one rotation angle sensor (rotary encoder) provided in the printing machine as a measurement trigger. The print color tone management apparatus according to claim 1, further comprising a unit.

Further, according to the present invention as defined in claim 3, the width of the measurement aperture of the spectral colorimetric head is associated with one unit width of the inking amount adjusting mechanism of the printing press.
The print color tone management apparatus according to claim 1, wherein the measurement data is associated with a control amount.

Further, the present invention according to claim 4 is such that at least one traverse device is installed in the vicinity of a carrying roller for traveling the printing paper and not in contact with the carrying roller and in parallel with the carrying roller. The spectral colorimetric head described above is movably provided by the traverse device,
By moving the color measurement head to a desired position using the traverse device and measuring it, it is possible to measure the whole or a part of the pattern printed on the running printing paper. The color tone management device according to any one of claims 1 to 3.

According to a fifth aspect of the present invention, in the traverse device in which the spectral colorimetric head is installed, the white calibration plate stands by in the vicinity of a stage section that moves together with the spectral colorimetric head. The print color tone management apparatus according to claim 1, wherein the print color tone management apparatus is provided in the print color tone management apparatus.

According to the present invention, the white calibration plate is installed at a desired position near the moving stage of the traverse apparatus in which the spectrocolorimetric head is installed, and the white calibration can be performed at any time and place. Is preferred.

The white calibration is a preparatory process for standardizing an arithmetic unit for calculating reflectance prior to the actual white calibration work, and using a white calibration plate whose reflectance is known,
The detection amount of the reflectance by the light receiving means in the spectrocolorimetric head is set to be the reference value.

Further, the measurement aperture width of the spectral colorimetric head is associated with one unit width of the inking amount adjusting mechanism of the printing press, so that the measured value is directly associated with the control amount. Associating the measured value with the controlled variable is effective in facilitating the processing of the measured value and simplifying the method of calculating the controlled variable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a print color tone management apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an outline of an offset winding rotary printing press to which a printing color tone management device is applied.

The roll paper arranged in the paper feed unit 2 is given a certain tension (tension) through the in-feed unit 4, the cooling unit (not shown) and the folding machine 30, and K (black), C
Color printing is performed by sequentially passing through the four color printing units 6a to 6d of (indigo), M (magenta), and Y (yellow).
The order and number of colors in the printing unit is just an example,
Not limited to the above. The printing units 6a to 6d have the same configuration, and only the upper body of the printing unit 6a will be described in detail.

The printing unit transfers the ink from the ink drum 18 and the plate cylinder 14 that is in contact with the blanket cylinder 10 that sandwiches the printing paper from above and below to the water cylinder 1 as well.
A large number of ink rollers 1 for transmitting dampening water from 7 to the plate cylinder 14.
It consists of 6 and 6. Although not shown, the ink fountain 18 is provided with a mechanism called an “ink key” for adjusting the amount of ink applied, and by adjusting the opening of this key, the amount of ink given to the plate cylinder 14 is adjusted. . A large number of ink keys are provided along the axial direction of the roller (direction perpendicular to the running direction of the paper surface), and the ink amount can be adjusted for each long and narrow ink key zone divided by the line along the running direction of the paper surface. It is possible. Although not shown, the ink amount can also be adjusted by an ink source roller that supplies ink from the ink fountain to the ink roller group 16. Therefore, there are an "ink key" and an "ink source roller" as a mechanism for adjusting the amount of ink applied.

The printing paper discharged from the printing unit 6d at the final stage is guided to a drying section, a cooling section, and a folding machine (not shown) to be a final printed matter. This final stage printing unit 6
A spectrocolorimetric head 22 is provided on the path of printing paper between the d and the folding machine 30.

The spectrocolorimetric head 22 measures the spectral reflectance of a pattern that enters a desired aperture area. Spectral reflectance is measured in a non-contact manner. Therefore, if the distance from the surface of the printing paper is large, it will be affected by ambient light, so accurate spectral waveforms cannot be obtained. .

Since the pattern is printed continuously and periodically,
In order to operate the measurement with the pattern area, a rotary encoder 24 for grasping the running state of the printing paper is attached to any one of the plate cylinder 14 in the printing unit, the cylinder of the folding machine 30, and the web pass roller. Although FIG. 1 shows a state in which the rotary encoder 24 is connected to the folding cylinder of the folding machine 30, it is desirable to attach the rotary encoder 24 to the roller measured by the spectrocolorimetric head 22.

The rotary encoder 24 generates a pulse every predetermined rotation number of the roller in synchronization with the running of the printing paper. The spectral colorimetric head 22 performs measurement according to the output pulse of the rotary encoder 24. As a result, the measurement is started / finished by the pulse signal from the rotary encoder 24.

As described above, the color tone of the print pattern is adjusted by changing the ink key opening arranged in the axial direction of the roller (direction orthogonal to the flow direction of the printing paper). For No. 22, it is necessary to measure the spectral reflectance for each ink key zone. for that reason,
The spectrocolorimetric head 22 associates the size of the measurement aperture with one unit width of the inking adjustment mechanism of the printing press, and further moves the traverse device by one unit width of the inking adjustment mechanism to repeatedly move and measure, It makes it possible to measure the entire surface of the printing paper in motion and to correlate the measured values with the control values.

Traverse (moving) the spectral colorimetric head 22
If you want to control the entire printing pattern, you can traverse the entire surface to obtain the measurement value.If you use it for monitoring only an arbitrary area, do not measure the unnecessary area and measure it. It is also possible to measure only. When only the required area is measured, the takt time of the measurement can be reduced, so that the measurement can be performed more efficiently.

The spectral colorimetric head 22 is from 400 nm to 7 nm.
The visible wavelength region of 00 nm is measured in 16 channels every 20 nm, and the infrared wavelength region of 1000 nm to 1400 nm is measured in 1 channel. The infrared region is measured to check the presence or absence of the black plate (Bk). There is no black version,
When black is printed by superimposing YMC, absorption does not appear in the wavelength region of 1000 nm to 1400 nm as shown in FIG. 2B, but when a black plate is present, FIG.
As shown in, absorption appears in the wavelength region of 1000 nm to 1400 nm.

The output from the spectral colorimetric head 22 is supplied to the color tone management device 28 via the measurement data processing unit 26.
The measurement data processing unit 26 calculates the reflectance from the output signal of the spectrocolorimetric head 22. The color tone management device 28 is composed of an ordinary personal computer or the like, and calculates the Lab color system and the optical density for each ink from the reflectance processed by the measurement data processing unit 26. Calculated Lab
The color difference ΔE is calculated using the values of the color system, the color difference of the print pattern is detected, and the display unit displays the detection result. Although not shown, an ink key opening signal based on the detection result is sent to the control unit of the printing machine, and the adjustment mechanism of the ink application amount such as the ink key opening is automatically controlled.

Although the reflectance of the spectrocolorimetric head 22 is measured, it may change over time depending on the operating environment of the measuring instrument and the usage conditions. Therefore, it is necessary to regularly calibrate the white color and calibrate the measured value.

Therefore, in this embodiment, the spectral colorimetric head 22 is used.
On the moving stage of the traverse device where is installed,
A white calibration plate fixed to a support having a vertical movement mechanism is installed so that white calibration can be performed at any time and place. (Refer to FIG. 5) FIG. 5 (on the left side ... At the time of measurement) is an explanatory view showing a state where the surface of the printing paper 36 is being color-measured, and the spectral colorimetric head 34 is close to the printing paper 36. When performing the white color calibration, as shown in FIG. 5 (right side, when retracted), the traverse device 32 moves the spectroscopic color measurement head 34 rearward from the paper surface (rightward in the direction perpendicular to the printing paper surface). Then, the white proof plate 30 is moved so as to face the measurement aperture (not shown) of the spectral colorimetric head 34, and the white calibration is performed.

As a result, the white color calibration can be performed immediately regardless of the position of the spectral colorimetric head 22 (even when the color tone management is being performed). It is possible to reduce the amount of white paper. It is possible to start the measurement from the stable state by performing white calibration in a short time until the mechanical state becomes stable after connecting the paper (connecting the roll paper) and after cleaning the blanket. Become.

Next, details of the operation according to the present embodiment will be described. Generally, in a printing work site, a reference sample is printed before the actual printing work is performed, and the color tone of an actual print pattern (measurement sample) is adjusted with this as a reference. The reference sample may be a proof-print that has been reviewed by the customer, a printed material that has been actually printed in the presence of the customer and has been approved by the customer, or a printed material that has been confirmed by a trained inspector. Then, the printing is actually started, and the printed matter obtained during the printing work satisfying any of the above conditions is used as a reference sample.

That is, when the desired color tone is obtained for the pattern on the printing paper, the operator inputs an instruction to the color tone management device 28, and the measured value at the time when the instruction is input is used as a reference. As shown in FIG. 3, the color tone management device 28 takes in the spectral reflectance of each of the ink key zones Z1 to Zn for each pattern.
The width of the ink key zone is the width of the ink key, and is, for example, 35 mm. The spectral colorimetric head 22 performs measurement according to the measurement pulse output from the rotary encoder 24. In one measurement, the area of 35 mm × 7 mm is measured. Holds the measurement value for each measurement pulse independently,
The measured values of the required area are averaged to obtain the reflectance of the desired area. In this way, in the pattern of the reference sample, the spectral reflectance (spectral waveform) of each ink key zone is input to the color tone management device 28 as the reference waveform.

The color tone management device 28 multiplies the spectral reflectance waveform by a color matching function to obtain a color value. In this embodiment, the L ^* a ^* b ^* color system standardized by the International Commission on Illumination (CIE) is adopted.

FIG. 4 shows an example of the measurement timing. The cutoff signal or the Z phase of the encoder is used as the encoder count cueing signal. After that, the measurement pulse divided from the encoder pulse is used as the measurement cueing signal. In this example, it is possible to extract the area in units of distance (7 mm) in which the desired area is moved to the interval of the measurement cueing signal.

Also in the measurement of an ordinary printed pattern (measurement sample), the spectral reflectance in the range corresponding to the measurement range of the reference sample is measured. The spectral waveform at this time is also supplied to the color tone management device 28, and the color value is obtained.

The difference in color tone between the reference sample and the measurement sample thus obtained is obtained as the difference in color value as follows,
Let this be ΔE ^* ab. ΔE ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ]
^1/2 where ΔL ^* is the L ^* value difference, Δa ^* is the a ^* value difference, and Δb ^*
Is the difference in b ^* values.

The color difference ΔE ^* ab is displayed on the display unit as a color tone deviation, and if the difference is not less than a predetermined threshold value,
When it is determined that the correction is necessary, the K, C, M, and Y ink amount adjustment signals corresponding to the difference are supplied to the ink keys of the printing machine units of the respective colors as opening control signals. Therefore, in the present embodiment, the color tone management device 28 uses the color difference ΔE ^* ab and K,
A table was prepared in which the correspondence with the C, M, and Y ink key openings was stored in advance. From this table, the color of the ink that seems to be effective for correction and the ink key opening adjustment amount are calculated. Here, a table of the correspondence relationship between the color value difference ΔE ^* ab and each ink key opening of K, C, M, and Y was prepared, but the relationship between the optical density difference of each ink color and the ink key opening adjustment amount Any method such as a method of calculating the ink key opening adjustment amount by a function indicating

If all the print patterns after the reference sample is obtained are measured as the print patterns to be measured, it is possible to immediately deal with the change in the color tone, but the change in the color tone is gradual, and the ink key opening is performed. Since it takes time for the amount of ink on the plate cylinder to change even if the degree is changed, the measurement may be performed every several tens of samples.

As described above, according to the present embodiment, the spectral colorimetric head 22 is attached to the printing machine to measure the spectral reflectance of a predetermined pattern area corresponding to each ink key of the running print. It is possible to obtain the color value of the measurement result and detect the deviation of the color tone according to the difference in the color value between the reference sample and the measurement sample. Therefore, it is possible to immediately detect the deviation of the color tone of the print pattern during printing and adjust the ink amount, so that the color tone of the print pattern can be made uniform without generating a large amount of defective printed matter. A special measuring device is required to measure one point of a pattern on a printing paper running at high speed, but a special measuring device is required to obtain the reflectance in a predetermined range as in the present embodiment. It is not necessary, and the shift in color tone can be detected with a spectral reflectance meter having a simple structure. Further, the range of the pattern to be measured may be limited to a particularly important color tone portion instead of the entire ink key zone.

The present invention is not limited to the above-mentioned embodiment, but can be modified in various ways. In the above description, the reflectances of the entire surface of the pattern are compared, but only the portion that is important in terms of color tone (for example, a skin-colored portion in the case of a person) may be used. In this case, it can be specified based on the ink key zone and the position of the measurement pulse.

[0042]

As described above, according to the present invention, the deviation of the color tone of each color in the printed pattern can be easily measured during printing without the need for a sampling inspection by a skilled inspector, and an appropriate ink adjustment can be made. A print color tone management device that can adjust the color tone quickly by determining the amount is provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a print color tone measuring device according to the present invention.

FIG. 2 is a diagram showing a difference in spectral reflectance characteristics depending on the presence or absence of a black plate.

FIG. 3 is a diagram showing a principle of measuring spectral reflectance.

FIG. 4 is a diagram showing an example of a measurement timing signal.

FIG. 5 is a diagram showing a state in which the spectral colorimetric head is retracted and white calibration is performed.

[Explanation of symbols]

4 ... Infeed section 6a, 6b, 6c, 6d ... Printing unit 10 ... Blanket body 16 ... Ink roller 17 ... Mizufune 18 ... Ink fountain 22. Spectral color measurement head 24 ... Rotary encoder 26 ... Measurement data processing unit 28 ... Color management device 30 ... White calibration plate 32 ... Traverse device 34 ... Measuring head 36 ... Paper

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Claims (5)

[Claims] 1. A spectrocolorimetric head that includes a light irradiating means and a light receiving means, and is capable of repeatedly performing multi-divisional measurement of the surface of a printed material in the running direction, and the spectroscopic colorimetric head with respect to the surface of the printed material. A traverse device capable of moving in a parallel direction, and the spectral colorimetric head such that the white calibration plate is arranged in the measuring section of the spectral colorimetric head when performing white color calibration of the spectral colorimetric head. Or a white calibration device equipped with a mechanism for moving at least one of the white calibration plates, and the reflectance of the printed matter is calculated based on the detection data of the reflected light received by the light receiving means of the spectral colorimetric head. And a data processing device. The data processing device detects measurement data for determining a color tone variation from the reflectance data calculated by the computation device, and if the color tone varies. Judge In such a case, in order to control the color tone variation, a control amount for the inking amount adjusting mechanism of the printing press is calculated, and based on the calculated control amount, control for the inking amount adjusting mechanism of the printing press is performed. A printing color tone management device characterized in that 2. A measurement control means for controlling measurement by using an output signal from at least one rotation angle sensor (rotary encoder) provided in the printing machine as a measurement trigger. The printing color tone management device according to claim 1. 3. The data of the measurement is associated with the control amount by associating the width of the measurement aperture of the spectral colorimetric head with one unit width of the inking amount adjusting mechanism of the printing press. The printing color tone management apparatus according to claim 1. 4. A traverse device installed in the vicinity of, and parallel to, a conveyance roller for moving a printing sheet, the traverse apparatus being provided with at least one or more of the spectral colorimetric heads. The traverse device is used to move the colorimetric head to a desired position to measure and measure the whole or part of the pattern printed on the running printing paper. The color tone management device according to any one of claims 1 to 3, wherein 5. A traverse device in which the spectroscopic colorimetric head is installed, wherein the white calibration plate is provided so as to stand by in the vicinity of a stage section that moves together with the spectroscopic colorimetric head. Item 5. The print color tone management device according to any one of items 1 to 4.