JPH08132595A - Ink supply volume controlling apparatus and method for multi-color printer - Google Patents

Abstract

PURPOSE: To improve the control accuracy of the color tone of a printed matter, to fall the tone of the matter within a variable range allowed as an article and to improve the productivity. CONSTITUTION: Control wavelengths 13, 13' of the wavelengths of minimum spectral reflectivity and target reflectivities 14, 14' are inspected based on the spectral reflectivity data 6 of a visible range obtained by scanning a monochromatic print color tone inspecting zone 2 on a print sheet 1 printed by a multi- color printer 20, the spectral reflectivity of the wavelength equal to the wavelength 13' is extracted from the data 6, the reflectivity 16 is compared with the reflectivity 14', and the deviation is calculated. Further, an ink volume increase or decrease signal 18 for minimizing the deviation is calculated, the signal 18 is sent to the ink supply volume regulator 19 of the printing unit of the printer 20 to improve the control accuracy of the color tone of the sheet 1, to fall the color tone of the printed matter within a variable range allowed as an article, and to improve the productivity of the printer 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink supply amount control device and method for a multicolor printing machine.

[0002]

2. Description of the Related Art In a multicolor printing machine, it is required that the color tone of a printed printing sheet agrees well with that of a printing sample called proof. For this reason, the print operator sometimes removes the print sheet being printed, visually compares the color tone of the printed matter with that of the sample, and if there is a difference in color tone difference between the two that exceeds the allowable range, the ink supply amount for each color is determined. Adjustment is made to minimize the color difference.

A great deal of skill is required to detect such a color tone difference and to adjust the ink supply amount to minimize this color tone difference, and this automation is desired from the viewpoint of reducing the load on the operator. There is. As one of the automation methods, there is an ink supply amount control device for a printing machine described in Japanese Patent Laid-Open No. 62-146633.

To explain this outline with reference to FIG. 5, a print sheet 1 printed by a printing machine 20 has a color tone inspection area (a single color printing portion for color tone inspection) 2 which is printed at the same time.
The chromaticity in an arbitrarily selected chromaticity coordinate system (for example, the International Commission on Illumination's L ^x a ^x b ^x system) in this shade inspection area 2 is measured as follows. 3 is a measuring head, and the measuring head 3 is movable in the width direction with respect to the monochromatic printing portion 2 for color tone inspection by a stepping motor 25 or the like driven by the measuring head drive controller 24.
The measuring head 3 has a measuring device (not shown) and sends the reflected light from the inspection area to the spectrometer 4. This spectrometer 4
Reflects the reflected light into a spectrum and sends the data obtained at that time to the spectral reflectance calculation device 5, and the spectral reflectance calculation device 5 obtains the spectral reflectance data 6. Then, the spectral reflectance data 6 is sent to the chromaticity calculation device 26, and the chromaticity in the chromaticity coordinate system arbitrarily selected here is calculated.

The chromaticity obtained as a result is sent to the control data arithmetic unit 17 as chromaticity data 27. Here, a color difference is obtained from the chromaticity data 27 and a preset target chromaticity, and an ink amount increase / decrease signal 18 for adjusting the ink supply device so as to minimize this color difference is calculated. By repeating such color measurement and ink amount adjustment to bring the color of the color tone inspection area 2 closer to the target chromaticity, the color tone of the entire print sheet 1 is adjusted to the target value.

[0006]

The conventional ink supply amount control device for a printing press shown in FIG. 5 has the following problems. That is, FIG. 5 shows an example of changes in the spectral reflection characteristics in the visible light region of the print sheet when the ink supply amount is increased or decreased.

As shown in FIG. 5, the spectral reflectance does not increase / decrease over the entire wavelength region of the visible region due to an increase / decrease in the ink supply amount, that is, the ink film thickness transferred onto the printing sheet. The spectral reflectance increases or decreases only in a specific wavelength range depending on the absorption characteristic. On the other hand, in the chromaticity calculation based on the spectral reflectance,
An average value of the spectral reflectances of the respective wavelengths multiplied by a separately determined weighting coefficient, that is, a kind of weighted average value is used as a basic amount. Details of this are described in JISZ8722.

When such a chromaticity calculation is carried out when the ink film thickness on the printing sheet and the change in the spectral reflectance exhibit the above-mentioned behavior, a wavelength region which is not affected by the change in the ink film thickness, that is, The spectral reflectance in the wavelength region that is insensitive to the change in the ink film thickness is also added to the chromaticity calculation, and the resulting chromaticity becomes insensitive to the change in the ink film thickness on the printing sheet.

In the ink supply amount control device that calculates the chromaticity of the printing sheet from the spectral reflectance distribution and controls the ink supply amount based on the calculated chromaticity, the control accuracy of the ink supply amount is lowered. For this reason, the color tone of the printed matter may not fall within the permissible variation range as a product, which may lead to deterioration in productivity.

The present invention has been proposed in view of the above problems, and an object thereof is to improve the control accuracy of the color tone of a printed matter and to keep the color tone of the printed matter within a fluctuation range allowable as a product. Another object of the present invention is to provide an ink supply amount control device and method for a multi-color printing machine, which can improve productivity.

[0011]

In order to achieve the above object, an ink supply amount control device for a multicolor printing machine according to the present invention comprises:
Measuring means for obtaining spectral reflectance data in the visible region by scanning a monochromatic color tone inspection area on a printing sheet printed by a multicolor printing machine, and spectral reflectance minimum based on the spectral reflectance data sent from the measuring means. And a control wavelength detecting unit for detecting a target wavelength and a control wavelength detecting unit, and a control wavelength storing unit for storing the control wavelength sent from the control wavelength detecting unit and target data sent from the outside, and the control wavelength detecting unit A target value storage device comprising a target reflectance storage unit for storing target reflectance and target data sent from the outside,
From the spectral reflectance data sent from the measuring means, a control reflectance extraction device that extracts the spectral reflectance of a wavelength equal to the control wavelength of the control wavelength storage unit as the control reflectance, and the control reflectance extraction device sends the spectral reflectance data. The control reflectance and the target reflectance sent from the target reflectance storage unit are compared to calculate a deviation between them, and then an ink amount increase / decrease signal that minimizes this deviation is calculated and the ink amount increase / decrease signal is printed. And a control data arithmetic unit for sending to the ink supply amount adjusting section of the printing unit of the machine (Claim 1).

Further, the ink supply amount control method for a multicolor printing machine of the present invention uses spectral reflectance data in the visible region obtained by scanning a monochromatic color tone inspection area on a printing sheet printed by the multicolor printing machine. The control wavelength and the target reflectance that are the minimum wavelengths of the spectral reflectance are detected based on the spectral reflectance, and the spectral reflectance of the wavelength equal to the control wavelength is extracted from the spectral reflectance data as the control reflectance. And the target reflectance are calculated to calculate a deviation between them and an ink amount increase / decrease signal that minimizes the difference is calculated, and the ink amount increase / decrease signal is sent to the ink supply amount adjusting unit of the printing unit of the printing press. It is characterized by sending (claim 2).

[0013]

The apparatus and method for controlling the ink supply amount of the multicolor printing machine according to the present invention is constructed as described above, and is obtained by scanning the monochromatic color tone inspection area on the printing sheet printed by the multicolor printing machine. Based on the spectral reflectance data in the visible region, the control wavelength and the target reflectance, which are the minimum wavelengths of the spectral reflectance, are detected, and the spectral reflectance of the wavelength equal to the control wavelength is controlled from the spectral reflectance data. The control amount and the target reflectance are compared to calculate the deviation between them, and the ink amount increase / decrease signal that minimizes the difference is calculated, and the ink amount increase / decrease signal is output to the printer. By feeding the ink to the ink supply amount adjusting section of the printing unit, the accuracy of controlling the color tone of the printed matter is improved, and the color tone of the printed matter is kept within the allowable range of variation as a product to improve the productivity.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink supply amount control apparatus and method for a multicolor printing machine according to the present invention will be described below with reference to an embodiment shown in FIGS. Reference numeral 20 in FIG. 1 denotes a printing machine, which is equivalent to a normal multicolor printing machine. The ink supply amount adjusting unit 19 of the printing machine 20 has a width direction of each color of a pattern to be printed. The ink supply amount for each color can be increased or decreased for each of several divided sections in the width direction according to the distribution of the ink consumption amount. At this time, in order to confirm the adequacy of the adjustment of the ink supply amount, the color tone inspection area 2 is formed on the print sheet 1 printed by the printing machine 20 at the same time as the original pattern for each of several divided sections in the width direction. Printing is performed in a strip shape that is long in the width direction by the number of colors of the ink used to print the original pattern.

3 is a measuring head, and this measuring head 3 is
It is movable in the width direction with respect to the color tone inspection area 2 by a stepping motor 25 driven by the measuring head drive controller 24. By the measuring head 3 movable in the width direction, the spectrometer 4 connected thereto, and the spectral reflectance calculation device 5 connected thereto, the ink supply amount in the width direction of the color tone inspection area 2 is scanned for each divided section. , Spectral reflectance data 6 is obtained.

The measuring head 3 has a measuring device (not shown). This measuring device irradiates the color tone inspection area 2 with visible light in a vertical direction by the light guide tube and guides the reflected light reflected from the color tone inspection area 2 at an angle of 45 ° to the spectrometer 4. Has become. As the spectrometer 4, for example, the one shown in FIG. 3 is used. In this spectrometer 4, the reflected light sent from the measurement head 3 via the light guide tube is sent to the right-angle prism 30 via the lens 28, and a real image is formed in front of the right-angle prism 30.
This real image enters the rectangular prism 30 and is totally reflected,
The interference filter array 3 is enlarged by the lens 29.
An enlarged real image is formed on the surface of 1. The interference filter array 31 includes, for example, a visible light wavelength region (400 to 700 n).
When m) is separated at intervals of 10 nm, 30 interference filters are arranged.

This interference filter array 31 is used to
The intensity of the reflected light separated into individual pieces is converted into 30 electrical measurement signals 33 by the photodiode array 32 in close contact with each interference filter, amplified by the multi-channel amplifier 34, and then the spectral reflectance calculation device. Sent to 5. Further, in the spectral reflectance calculation device 5, the spectrometer 4
Spectral reflectance data 6 is obtained by dividing the plurality of spectral reflection intensity signals sent from the product by the spectral reflection intensity signal for the perfect diffuse reflection surface at each spectral wavelength obtained by the calibration work performed separately. .

Hereinafter, the ink supply amount is controlled in the following manner for each monochromatic printing section for each divided section. At the start of printing, the control target value is set by one of the following. (1) When setting the control target value based on the measurement result. A push button (not shown) or the like is operated, the switch 35 is switched, and the spectral reflectance calculation device 5 is connected to the control wavelength detection unit 9 of the target value storage device 8 via point C in FIG. The reflectance data 6 is obtained by the measuring head 3, the spectrometer 4, and the spectral reflectance calculation device 5 to obtain the spectral reflectance data 6 of the corresponding monochromatic portion of the reference image such as a sample print. In this case, the measured spectral reflectance data 6 becomes the spectral reflectance data 7 of the reference image such as a sample print and is sent to the control wavelength detecting unit 9 of the target value storage device 8.

In the target value storage device 8, first, the control wavelength detecting section 9 compares a plurality of spectral reflectance data 7 of a reference image such as a sample print with each other to control the wavelength which shows the minimum spectral reflectance. The wavelength 13 and the spectral reflectance (target reflectance) at the control wavelength 13 are detected. And control wavelength 13
Is sent to the control wavelength storage unit 10, and the control wavelength stored therein up to that point is updated to the control wavelength 13 and stored in the control wavelength storage unit 10. Similarly, the target reflectance 14 is also sent to the target reflectance storage unit 11,
The target reflectivity stored therein is updated to the target reflectivity 14 and stored in the control wavelength storage unit 10. (2) When setting the target value for control by the data separately input from the outside.

Spectral reflectance data 6 is measured by a different measuring device with respect to the color tone inspection area 2 such as sample printing, and the data obtained at that time are compared with each other to obtain the control wavelength and the target reflectance. This is the target reflectance storage unit 1 from the external input device (not shown) as the external input target data 12.
1 is directly sent to the control wavelength storage unit 10 and is updated and stored therein.

After setting the control target value as described above,
A push button (not shown) or the like is operated, the switch 35 is switched, and the spectral reflectance data 6 is set to pass through point B in FIG. As a result, the color tone is actually inspected and made to correspond to the print sheet to be controlled (called an inspection image). In the above setting, the spectral reflectance data 6 obtained by the measuring head 3, the spectrometer 4, and the spectral reflectance calculation device 5 becomes the spectral reflectance data 15 of the inspection image. This data 15 is sent to the control reflectance extraction device 36, where the spectral reflectance of the wavelength equal to the control wavelength 13 'input from the control wavelength storage unit 10 is extracted as the control reflectance 16,
It is sent to the control data arithmetic unit 17.

FIG. 2 shows the control data arithmetic unit 17. In this control data calculation device 17, the target reflectance 14 'from the target value storage device 8 (target reflectance storage unit 11) is used.
And the control reflectance 16 from the control reflectance extraction device 36 are input to the deviation calculator 21. In the deviation calculator 21,
Both are compared, the deviation 22 is calculated, and the deviation 22 is calculated.
Is sent to the correction amount calculation unit 33, and in the correction amount calculation unit 33, the deviation 22 is calculated as the ink amount increase / decrease signal 18 by the equation for converting to the ink correction amount, and the ink amount increase / decrease signal 18 changes the color tone inspection area 2. It is sent to the ink supply amount adjusting unit 19 of the printing unit of the printing machine 20 for printing.

By repeating the above-described spectral reflectance measurement and ink amount adjustment for each single color portion of the color tone inspection area 2 on the print sample extracted for the color tone inspection, the color tone of the inspection area is targeted. The color is kept close to the target value until the end of printing. as a result,
The color tone of the entire print sheet 1 is adjusted to the target value.

When the target value of the color tone is changed during printing, the automatic control is temporarily interrupted, the color matching is manually performed, and the reference image for sample printing, that is, O
The K printing sheet is taken, and thereafter, the control wavelength and the target reflectance are updated and stored in accordance with the case where the target value is set based on the measurement result of the reference image, and the automatic control may be performed. Specifically, after a reference image such as a sample print is acquired again by manual color matching, a push button (not shown) is operated to switch the switch 35 so that the spectral reflectance data passes through point C in FIG. After that, the spectral reflectance data 6 may be measured by the measuring head 3, the spectrometer 4, and the spectral reflectance calculating device 5 to measure the spectral reflectance of the corresponding single-color portion of the acquired reference image such as a sample print.

In order to perform automatic control of the inspection image to be controlled again, a push button (not shown) is operated, the switch 35 is switched, and the spectral reflectance data 6 is set so as to pass through point B in FIG. I need to start over. It should be noted that measuring the spectral reflectance distribution in the visible region of the color tone inspection area 2 of the print sheet printed by the printing machine with the spectrometer 4 illustrated in FIG.
Although it is the same as the conventional one, the measurement target is only the color tone inspection area 2 for monochromatic printing.

Then, based on the spectral reflectance distribution measured on the reference image (sample printing, proof printing, OK printing sheet) which is the target of color adjustment, the wavelength at which the monochromatic printing ink absorbs most visible light is determined. That is, a wavelength having a minimum spectral reflectance, for example, a wavelength at point A in FIG. 4 (this wavelength is called a control wavelength) is selected, and the spectral reflectance measured at this control wavelength is stored as a target value. This is compared with the spectral reflectance of the control wavelength to calculate the deviation, and then an ink amount increase / decrease signal 18 for minimizing this deviation is sent to the ink supply amount adjusting unit 19 of the printing machine 20. By making the color of the print sheet 1 in the color tone inspection area 2 closer to the target color, the color tone of the entire print sheet is made to match the target color.

[0027]

As described above, the apparatus and method for controlling the ink supply amount of the multicolor printing machine according to the present invention has a visible region obtained by scanning the monochromatic color tone inspection area on the printing sheet printed by the multicolor printing machine as described above. Based on the spectral reflectance data, the control wavelength and the target reflectance, which are the minimum wavelengths of the spectral reflectance, are detected, and the spectral reflectance of the wavelength equal to the control wavelength is extracted from the spectral reflectance data as the control reflectance. Then, the control reflectance and the target reflectance are compared to calculate the deviation between them, and the ink amount increase / decrease signal that minimizes the difference is calculated, and the ink amount increase / decrease signal is output to the printing unit of the printing machine. Since it is sent to the ink supply amount adjusting unit, the control accuracy of the color tone of the printed matter can be improved, and the color tone of the printed matter can be kept within the fluctuation range permitted as a product, and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing a configuration example of an ink supply amount control device used for carrying out an ink supply amount control method for a multicolor printing machine according to the present invention.

FIG. 2 is a system diagram showing a control data calculation device of the ink supply amount control device.

FIG. 3 is an explanatory diagram showing a spectroscopic system of the same ink supply amount control device.

FIG. 4 is an explanatory diagram showing a change in spectral reflectance distribution on a print sheet with an increase or decrease in ink amount.

FIG. 5 is a system diagram showing an ink supply amount control device of a conventional printing machine.

[Explanation of Codes] 1 Printed Print Sheet 2 Color Tone Inspection Area (Color Tone Inspection Single Color Printing Section) 3 Measuring Head 4 Spectrometer 5 Spectral Reflectance Calculation Device 6 Spectral Reflection Data 7 〃 8 Target Value Storage 9 Control Wavelength Detecting unit 10 Control wavelength storage unit 11 Target reflectance storage unit 13 Control wavelength 13 'Control wavelength 14 Target reflectance 14' Target reflectance 15 Spectral reflectance data 16 Control reflectance 17 Control data calculator 18 Ink amount increase / decrease signal 19 Printing Ink supply amount adjusting unit of printing machine 20 Printing machine 21 Deviation calculation unit 22 Deviation 23 Correction amount calculation unit 36 Control reflectance extraction device

Claims (2)

[Claims] 1. A measuring device for obtaining spectral reflectance data in the visible region by scanning a monochromatic color tone inspection area on a printing sheet printed by a multicolor printing machine, and based on the spectral reflectance data sent from the measuring device. Control wavelength which is the minimum wavelength of the spectral reflectance and a control wavelength detecting section for detecting the target reflectance, and a control wavelength storing section for storing the control wavelength sent from the control wavelength detecting section and the target data sent from the outside, and the control. A target value storage device including a target reflectance storage unit that stores target reflectance sent from the wavelength detection unit and target data sent from the outside, and the control wavelength storage from the spectral reflectance data sent from the measuring unit. Control reflectance extraction device for extracting the spectral reflectance having a wavelength equal to the control wavelength of the control unit as the control reflectance, the control reflectance sent from the control reflectance extraction device, and the target reflection. After calculating the deviation between each other by comparing it with the target reflectance sent from the rate storage unit, the ink amount increase / decrease signal that minimizes this deviation is calculated, and this ink amount increase / decrease signal is used as the ink supply amount of the printing unit of the printing machine. An ink supply amount control device for a multi-color printing machine, comprising a control data calculation device for sending to an adjusting section. 2. A control wavelength and a target which are wavelengths having a minimum spectral reflectance based on spectral reflectance data in a visible region obtained by scanning a monochromatic color tone inspection area on a printing sheet printed by a multicolor printing machine. The reflectance is detected, and the spectral reflectance of the wavelength equal to the control wavelength is extracted from the spectral reflectance data as the control reflectance, and the control reflectance and the target reflectance are compared to determine the deviation between them. Ink supply amount of multicolor printing machine characterized by calculating and calculating an ink amount increase / decrease signal that minimizes this deviation, and sending this ink amount increase / decrease signal to the ink supply amount adjusting section of the printing unit of the printing machine. Control method.