JP2000246871A - Color correcting apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct the amt. of compounding of a colored liq. to the condition before color change when the color change of a printed matter after printing has been detected, and to improve quality of the printed matter. SOLUTION: In this color correcting method, a printing ink A extracted from a container is irradiated with a light to measure spectral properties of the transmitted light by means of a liq. monitor part 6a-6d and spectral reflectance of the printing ink A printed an a web printing sheet 4 is measured by means of a printed article monitoring part 5 and a value of the color is calculated from the spectral reflectance by means of an operation controlling part 7 to judge existence of change in color change. When it is judged that there exists change in the color value, the liq. monitor parts 6a-6d operate amt. ΔCi of addition of amt. of compounding of the printing ink A in a container based on the change of the spectral transmittance T(λ), and a base ink (a colored liq.) or a reducer (a transparent liq.) is fed into the container according to the amt. ΔCi of addition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring the color of a colored liquid for printing (specific examples are inks, except for special cases) and the color of printed matter, for example, in the printing field. The present invention relates to a color correction device and a color correction method capable of correcting the blending amount of a colored liquid to a state before the color change when a color change of the color is detected.

[0002]

2. Description of the Related Art Conventionally, for example, in a printing process using a coloring liquid such as ink, paint, plastic or the like, when a coloring liquid contained in a container is repeatedly printed on a continuously supplied printing sheet, visual or The color of a printed printing sheet (hereinafter referred to as a printed matter) is managed by colorimetry, and the quality of the printed matter is kept constant.

[0003] Specifically, a primary colorant (base ink) to be added is selected so that the current visually or colorimetric color matches the target color visually or colorimetrically measured immediately after the start of printing. A color correction method is known in which the additional amount is determined by trial and error or the printing conditions are changed, and the blending amount of the coloring liquid is corrected so that the color of the printed matter is constant.

In this type of color correction method, in order to reduce the load on a skilled person, instead of visual observation, when measuring the color of the colored liquid, the colored liquid is extracted into a colorimetric cell and the color is measured in a solution state. Technology that can be applied. For example, JP-A-61-
JP-A-56923 and JP-A-61-65123 disclose a method in which a light guide and a detection probe are immersed in a colored liquid for color measurement.

Japanese Patent Application Laid-Open No. 6-50819 discloses that
There is disclosed a method in which light is incident on a liquid surface of a colored liquid at a predetermined incident angle at the time of color measurement of a paint or the like having a high concealing property, and reflected light in a vertical direction is detected by a color sensor.

[0006]

However, in the above-described color correction methods, all of the colorimetric methods are inadequate for colorimetric measurement of a colored liquid, as described below, so that the quality of printed matter is degraded. There is a possibility that it will be done.

For example, in the case of a method in which the light guide is immersed, since the colorimetric cell cannot be rapidly washed, the coloring component adheres to the glass of the colorimetric cell and the complete coloring component adheres to the glass. Removal is difficult. In addition, since the color that has changed color is detected by the attached coloring component,
The color measurement result will be inaccurate.

Further, this method requires a wiping device for the detection probe, and may damage the tip of the probe due to repeated wiping. On the other hand, a method of detecting reflected light is limited to a coloring liquid having a high concealing property such as a paint, and cannot be applied to a coloring liquid having a high transparency such as gravure ink. The reason is that in the case of a colored liquid with a high concealing property, the color applied to a support such as paper and the color in a solution state are not affected by the color of the base, and the reflected light can be measured. However, in the case of a highly transparent colored liquid, the color applied to the support is different from the color in the solution state because the color of the base is affected.

The present invention has been made in view of the above circumstances, and when the color change of a printed product is detected, the compounding amount of the coloring liquid can be corrected to a state before the color change, thereby improving the quality of the printed product. It is an object of the present invention to provide a color correction device and a color correction method which can be performed.

Another object of the present invention is to prevent the adhesion of a coloring component to a measuring cell and to apply it to a highly transparent coloring liquid.

[0011]

According to a first aspect of the present invention, there is provided an ink jet printer, comprising: a printing apparatus that prints a color liquid contained in a container repeatedly on a continuously supplied printing sheet; A color correction device for correcting the color liquid to a constant value, a liquid monitor unit that samples the colored liquid in the container, irradiates the colored liquid with light as it is, and measures the spectral characteristics of the reflected or transmitted light. And a print monitor for measuring the spectral reflectance of the colored liquid printed on the print sheet; and calculating a color value from the spectral reflectance measured by the print monitor, and calculating the color based on the calculation result. A color change determining unit that determines whether there is a change in the value, and when the color change determining unit determines that there is a change in the color value, based on the change in the spectral characteristic measured by the liquid monitor unit, the container. Means for calculating a change in the amount of compounding of the colored liquid, and a compound correction for supplying the colored liquid or the transparent liquid into the container so as to correct the amount of change calculated by the means for calculating change in the liquid to zero. And a color correction device comprising:

According to a second aspect of the present invention, in the color correction apparatus according to the first aspect, the liquid monitor section includes two transparent parallel flat plates which are arranged to face each other and whose interval is adjustable. A measuring cell having a liquid supply port and a liquid discharge port for passing the colored liquid between the parallel plates, and an incident optical system for allowing light to enter the colored liquid between the parallel plates. And a spectrophotometer for measuring the transmittance of transmitted light passing through the colored liquid between the parallel plates when light is incident by the incident optical system.

Further, according to a third aspect of the present invention, when the coloring liquid contained in the container is repeatedly printed on a continuously supplied printing sheet, the color of the coloring liquid on the printing sheet is fixed. A color correction method for sampling the colored liquid in the container, irradiating the colored liquid with light as it is, and measuring the spectral characteristics of the reflected or transmitted light; and A printed matter monitoring step of measuring the spectral reflectance of the colored liquid printed on the sheet, and calculating a color value from the spectral reflectance measured by the printed matter monitoring step, based on the calculation result, the change of the color value is calculated. A color change determining step of determining the presence or absence of the container based on a change in spectral characteristics measured by the liquid monitoring step when it is determined that the color value has changed by the color change determining step; A compounding change calculating step of calculating a changing amount of the compounding amount of the colored liquid in the above, and a compounding correction supplying the colored liquid or the transparent liquid into the container so as to correct the amount of change calculated in the compounding change calculating step to zero. And a color correction method.

As a specific measure for measuring the color of the colored liquid, for example, a colored liquid is filled between transparent parallel plates in a colored liquid in a container to form a thin film of the colored liquid. It is preferable to measure the reflectance or transmittance of the thin film.

(Operation) Therefore, in the invention corresponding to the first and third aspects, by taking the above means, the liquid monitor section samples the colored liquid in the container and converts the sampled liquid to the colored liquid as it is. Irradiate the light, measure the spectral characteristics of the reflected or transmitted light, the printed matter monitor section measures the spectral reflectance of the colored liquid printed on the print sheet, and the color change determination means is measured by the printed matter monitor section. Calculating the color value from the calculated spectral reflectance, based on the calculation result, determines the presence or absence of a change in the color value, the combination change calculation means, when the color change determination means is determined to have a color value change, Based on the change in the spectral characteristics measured by the liquid monitor unit, the change amount of the compounding amount of the colored liquid in the container is calculated, and the compounding correction unit corrects the change amount calculated by the compounding change calculating unit to zero. like Since the colored liquid or the transparent liquid is supplied into the container, when the color change of the printed printed matter is detected, the compounding amount of the colored liquid can be corrected to a state before the color change, and the quality of the printed matter can be improved. .

According to a second aspect of the present invention, as the liquid monitor section, there are provided two transparent parallel flat plates which are arranged opposite to each other and whose distance is adjustable, and the colored liquid passes between the parallel flat plates. A measuring cell provided with a liquid supply port and a liquid discharge port for causing the liquid to enter the colored liquid between the parallel plates; and an input optical system for inputting light to the colored liquid between the parallel plates. And a spectrophotometer for measuring the transmittance of the transmitted light that passes through the colored liquid, so that in addition to the action corresponding to claim 1, the colored liquid is passed through the measurement cell, By measuring the transmittance of transmitted light while preventing the coloring component from adhering to the cell, it can be applied to a highly transparent colored liquid.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a schematic configuration of a printing system to which a color correction device according to an embodiment of the present invention is applied, and FIG. 2 is a schematic diagram illustrating a concept of a print monitor unit applied to the color correction device. It is.

This color correction device is composed of a paper feed unit 1, 4 colors (yellow,
(Red, indigo, reducer) printing units 2a to 2d, drying unit (not shown), cooling / web path unit 3 (previous stage is shown)
And a folding section (not shown), and a tank (also referred to as a container or an ink pan) in each of the printing units 2a to 2d for a web (rolled paper) printing sheet 4 continuously supplied from the paper feeding section 1; This will be described by taking as an example a case where a known gravure rotary press that repeatedly prints each of the colored liquids (hereinafter, also referred to as printing inks) stored in the gravure press.

Specifically, a printing unit monitor unit 5 is provided near the web print sheet 4 between the drying unit and the cooling / web path unit 3.
Are arranged, and the liquid monitoring units 6a to 6d are arranged in the respective printing units 2a to 2d.
An operation control unit 7 is provided between them.

As shown in FIGS. 2 and 3, the print monitor 5 includes a light source unit 8, a sensor 9, a scanning unit 10, a colorimetric unit 11, a display unit (PC; personal computer) 12, and these light sources. A stabilized power supply (AVR; automatic volta) for the unit 8, the sensor 9, the scanning unit 10, the colorimetric unit 11, and the display unit 12.
ge regulator) 13.

The light source section 8 is for making light incident on the web print sheet 4, and more specifically, a halogen lamp that generates white light is used. However, instead of the halogen lamp, the light source unit 8 may use a tungsten lamp or a xenon lamp having a relatively wide emission wavelength range, or may use an ultra-high pressure mercury lamp.

The sensor 9 is arranged in proximity to the running web print sheet 4 after drying, and is scanned by the scanning unit 10 in the width direction W orthogonal to the running direction R of the web print sheet 4. Has a function of detecting the reflected light from the colorimeter and providing a detection signal to the colorimetric unit 11. Note that the sensor 9 may be a fixed type instead of the scanning type.
Optical design such as providing an inclination of 5 degrees or the like is appropriately performed.

The scanning section 10 is for scanning the sensor, and is connected to the breaker 10 connected to the stabilizing power supply 13.
a, a scanning relay 10b and a sequencer 10c, and a control signal of the sensor is transmitted from the sequencer 10c to the display unit 1.
2 RC232-C 12a and SCSI (small compu)
It has a function to give to the sensor 9 via the 12b.

The colorimetric section 11 has a function of measuring the spectral reflectance of the reflected light based on the detection signal received from the sensor 9 and transmitting the measurement result to the display section 12 and the arithmetic control section 7.

The display section 12 is for displaying a measurement result received from the colorimetry section 11, and for example, a general-purpose personal computer can be used.

The arithmetic control unit 7 has a function of giving an instruction for colorimetry to both the print monitor unit 5 and the liquid monitor units 6a to 6d at the same time, and L ^* a ^{* based} on the spectral reflectance measured by the print monitor unit 5 ^. a function of calculating a color value such as a b ^* value, calculating a difference (hereinafter also referred to as a color difference) of an L ^* a ^* b ^* value from a previous print lot, and determining whether the print color is good or not based on the color difference; A function of determining a failure when the color difference exceeds the upper limit of the standard and transmitting a failure detection signal at the time of failure determination and history information (for example, at the time of 300 m printing) at a time when the color difference is minimum to the liquid monitor units 6a to 6d. And have

Next, the structure of each of the liquid monitor units 6a to 6d will be described. Since the liquid monitor units 6a to 6d have the same structure except for the colors to be handled, one liquid monitor unit 6a is a representative example. I will list them.

As shown in FIG. 4, the liquid monitor 6a
First and second flat glass portions 21 and 2 each of which is composed of two transparent parallel flat substrates which are arranged opposite to each other and whose distance is adjustable.
A film forming apparatus 20 including a measuring cell having a liquid supply port 23a and a liquid discharge port 23b for passing a colored liquid between the first and second flat glass portions 21 and 22; A light incident on the colored liquid between the first and second flat glass portions 21 and 22 in the film forming apparatus 20; The apparatus includes a spectrophotometer 31 for measuring the transmittance of transmitted light that passes through the colored liquid between the flat glass portions 21 and 22, and a calculator 32 that performs color correction based on the measurement result.

Here, the film forming apparatus 20 is provided with a first flat glass portion 21 as a bottom portion, and stands upright on the periphery of the first flat glass portion 21, and a liquid supply port 23a and a liquid discharge port 23b for coloring liquid are provided. Formed housing glass 23
A piston case 24 having a cylindrical shape with openings at both ends in which a convex portion 24a is formed at the center of the inner wall, and a lower opening 24b provided to accommodate the housing glass 23 in the cylinder; An upper and lower piston 26 that holds a slidable piston glass 25 on the inner wall of the glass 23 and is formed at the center of the outer wall to be engaged with the piston case protrusion 24a and is slidable on the piston case protrusion 24a. And a cover member 2 provided on the piston case 24 for holding the outer wall on the rear end side of the upper and lower piston 26 so as to be able to advance and retreat.
7 and a drive unit for driving the upper and lower pistons 26 so as to be able to advance and retreat.

Here, the first flat glass portion 21, the housing glass 23, the piston glass 25, and the second flat glass portion 22 at the bottom of the piston glass are formed of a transparent material such as quartz glass, synthetic quartz glass or BK7 glass. ing.

It is to be noted that at least the first flat glass portion 21 and the second flat glass portion 22 disposed in parallel with and opposed to this first flat glass portion
Since there is a case where they come into contact with each other as in the case of zero alignment of the gap, a material having sufficient hardness in addition to the transparent property is preferable, and furthermore, the contact surfaces of each other are formed smoothly. Is desirable.

The first and second flat glass portions 21 and
2. The housing glass 23 and the piston glass 25
A water-repellent layer (not shown) made of a fluororesin thin film (thickness of several nm to several tens of nm) is provided on the surface of the internal space (cell for measurement) in contact with the coloring liquid.

The liquid supply port 23a and the liquid discharge port 23b are formed so that the inner and outer peripheral portions of the housing glass 23 communicate with each other, and are arranged to face each other via the optical axis. One end of a first conduit 28a for introducing, for example, a printing ink A as a coloring liquid is connected to the liquid supply port 23a. The other end of the first conduit 28a is provided as a colored liquid supply via a check valve 29a.
For example, it is communicated with an ink pan 30a containing the printing ink A.

On the other hand, the liquid discharge port 23b is connected to the second conduit 2
8b is connected to one end. The other end of the second conduit 28b is connected to the waste ink pan 30b via a check valve 29b.

The piston glass 25 is hollow inside and holds a spectrophotometer 31 to be described later. The second flat glass portion 22 at the bottom of the piston glass is lowered by the lowering of the first flat glass portion. 21 and the first and second flat glass portions 2 forming parallel flat plates with each other.
A gap for forming a thin film of the colored liquid (printing ink A) is formed between 1 and 22. The value of the gap is, for example, between several microns and several tens of microns, and an appropriate value is selected in advance according to the concealing property of the ink A so that the transmitted light amount is at least a predetermined value or more. When the film thickness is constant, when measuring the color of the ink A having a high concealing property,
This is because the obtained spectral characteristics become inaccurate due to the insufficient amount of transmitted light. An appropriate value of the gap is considered to be about 5 to 20 microns in the case of gravure ink.

As the driving unit, a fluid pressure cylinder such as air for moving the vertical piston 26 up and down is used. The driving section has a performance capable of controlling a submicron position formed in a desired gap of a micron unit (several μm to several tens μm) between the first and second flat glass sections 21 and 22. If so, a stepping motor or a servomotor may be used instead of the fluid pressure cylinder.

The fluid pressure cylinder includes a fluid pressure source 33 for supplying a fluid for driving the upper and lower pistons 26, and a convex portion 26.
A piston having an upper communication port 24c formed above the inner peripheral surface and communicating the inner peripheral surface with the outer peripheral surface, and a lower communication port 24d formed below the convex portion 26b and communicating the inner peripheral surface with the outer peripheral surface. An upper solenoid valve 34a for communicating or blocking between the case 24, the fluid pressure source 33 and the upper communication port 24c.
And a lower solenoid valve 34b for communicating or blocking between the fluid pressure source 33 and the lower communication port 24d.

That is, the fluid pressure cylinder has a function of pushing down the upper and lower pistons 26 together with the protrusions 26a by the fluid introduced from the fluid pressure source 33 by opening the upper solenoid valve 34a, and a function of opening and closing the same lower solenoid valve 34b. It has a function of pushing up the piston 26 together with the projection 26a.

The piston case 24 is provided with position sensors 35a and 35b for detecting the upper and lower pistons 26 positioned at the lower limit and the upper and lower pistons 26 positioned at the upper limit, respectively, and sending them to a computer 32 described later. . The position of the upper and lower pistons 26 can be regulated based on the detection results of the position sensors 35a and 35b.

The incident optical system is disposed below the first flat glass portion 21 of the film forming apparatus 20 and is provided with the first flat glass portion 21.
It has a light source unit 36 for irradiating the interposed colored liquid with light. As the light source unit 36, a 100 W halogen lamp that generates white light and a light guide for introducing white light are used, but a tungsten lamp or a xenon lamp having a relatively wide emission wavelength range may be used, or An ultra-high pressure mercury lamp may be used.

The spectrophotometer 31 is held in the piston glass 25 and the second flat glass portion 2 at the bottom of the piston glass is provided.
The photomultiplier tube (photomultiplier; related to the transmitted light transmitted through the colored liquid in the gap between
Hamamatsu Photonics) has the function of detecting the amount of transmitted light, the grating and the CCD array measuring the spectral transmittance T (λ), and giving the measurement result to the computer 32.

The spectral transmittance T (λ) is about 400 n
The visible light region of m to 700 nm is measured at intervals of, for example, 20 nm. Further, the spectrophotometer 31 may use a filter instead of the grating.

The computer 32 holds the spectral transmittance T (λ) received from the spectrophotometer 31 in chronological order, and transmits a defect detection signal and history information (indicating the color at the optimal time) from the arithmetic and control unit 7. When received, the spectral transmittance To (λ) at the optimum time is converted into an absorption coefficient Ko (λ), and the spectral transmittance Tf (λ) at the time of a failure determination is converted into an absorption coefficient Kf (λ).
Based on the difference between the two absorption coefficients {Ko (λ) -Kf (λ)}, an additional amount ΔCi of the base ink added to the container of the printing unit is calculated, and the base ink in the external tank is calculated according to the calculation result. It has a color correction function that is added to the inside of the container of the printing unit via piping equipment (not shown).

The computer 32, which can be omitted, controls the fluid pressure cylinder based on the detection results of the position sensors 35a and 35b, and measures the upper and lower pistons 26 while regulating the lowering position or the raising position. A function of lowering the color before the color and raising the color after the color measurement is completed may be provided.

Since the lowering position of the upper and lower pistons 26 is actually restricted by the contact of the second flat glass portion 22 with the first flat glass portion 21, the lowering position of the upper and lower pistons at the lower limit is detected. The position sensor 35a may be omitted, or may be modified to send a detection signal slightly before the lower limit.

Next, a color correction method using such a color correction device will be described with reference to the flowchart of FIG.

Now, in the liquid monitor sections 6a to 6d, it is assumed that the first and second flat glass sections 21 and 22 have an interval of several mm (ST1). The printing ink A in the ink pan 30a is driven by driving a vacuum pump or the like (not shown).
Flows into the measuring cell through the liquid supply port 23a,
The liquid is discharged from the liquid discharge port 23b while passing between the first and second flat glass portions 21 and 22 (ST2).

Next, the cylinder glass 25 is lowered by the fluid pressure cylinder (ST3), and the printing ink A is crushed until a predetermined interval is reached. From the nozzle.

As a result, in the film forming apparatus 20,
A thin film of the printing ink A is formed in micron units passing between the first and second glass portions 21 and 22 of the parallel plane (S).
T4).

Thereafter, the liquid monitor units 6a to 6d irradiate light from the light source unit 36 to the printing ink A sampled from the ink pan 30a and passing through the measuring cell. The print monitor 5 irradiates the web print sheet 4 with light from the light source 8 (ST5). As a result, both monitor units 5, 6a to 6d are in a state where colorimetry is possible.

Here, the gravure rotary press starts printing, and repeatedly prints the printing ink contained in the containers in the printing units 2a to 2d on the continuously supplied web printing sheet 4 (ST6). At this time, the arithmetic control unit 7
An instruction to measure the spectral characteristics is given to both the liquid monitor units 6a to 6d and the printed matter monitor unit 5 simultaneously at regular intervals of a predetermined printing length (or a predetermined time) (ST7).

The liquid monitoring units 6a to 6d are
, The spectral transmittance T (λ) of the transmitted light transmitted through the colored liquid is measured, and the obtained spectral transmittance T (λ) is obtained.
And history information, such as 100 meters (or measurement time) from the start of printing, are stored as a set.

On the other hand, the print monitor 5 measures the spectral reflectance of the colored liquid printed on the print sheet (ST8),
The obtained spectral reflectance is provided to the arithmetic and control unit 7.

The arithmetic control unit 7 calculates an L ^* a ^* b ^* value as a color value from the spectral reflectance (ST9; color change determination means), and calculates the L ^* a ^* b ^* value from the previously measured L ^* a ^* b ^* value. Calculate the color difference and determine whether the color difference has exceeded the upper limit of the standard.
The presence or absence of a change in the L ^* a ^* b ^* values, that is, the quality of the printed matter is determined (ST10: color change determination unit).

The L ^* a ^* b ^* value corresponds to the color of the printed matter. As shown in FIG. 6, due to the influence of fluctuation factors such as ink change and printing condition change due to temperature change during the printing process, It fluctuates every moment, but it is desirable that it be as constant as possible.

When the current L ^* a ^* b ^* value does not change, the arithmetic control unit 7 determines that the quality of the printed matter is "good", and determines the L ^* a ^* b ^* value and the start of printing. And the history information such as 100 meters (or measurement time) are stored as a set (ST11).

The arithmetic control unit 7 determines whether the current L ^* a ^* b
^* When there is a change in the value, the quality of the printed matter is determined to be "defective", and the failure detection signal at the time of the failure determination and the history information at the optimal time when the color difference is the minimum are determined by the liquid monitor units 6a to
6d (ST12).

When the liquid monitor units 6a to 6d receive the defect detection signal and the history information of the optimum time, the liquid monitor units 6a to 6d read out the spectral transmittance Tf (λ) at the time of the current failure judgment based on the defect detection signal, and Based on the information, the spectral transmittance To (λ) at the optimal time is read.

The liquid monitor units 6a to 6d calculate the spectral transmittance To (λ) of the colored liquid at the optimal time by the absorption coefficient Ko.
And the spectral transmittance Tf (λ) of the colored liquid at the time of the defect determination is converted into an absorption coefficient Kf (ST13; blending change calculating means).

In general, for a liquid having high transparency, assuming that the thickness of the liquid is X, the absorption coefficient K and the transmittance T have the relationship of the following equation (1). K = ln (T) / X (1) Here, since X is the film thickness at the time of measurement and is constant, equation (1) is equivalent to the following equation (2).

K = −ln (T) (2) This equation (2) shows that the transmittance T can be converted into an absorption coefficient K. That is, the liquid monitor units 6a to 6d
Uses the equation (2) to calculate the spectral transmittance T (λ) and the absorption coefficient K
(Λ).

Subsequently, the liquid monitor units 6a to 6d calculate the correction content of the blending amount using the following equation (3).

(Equation 1)

Here, Ci is the blending amount of the i-th base ink supplied to a certain printing unit 2a, for example, and (K) i is the absorption coefficient of the i-th base ink. (K) mix is, for example, an absorption coefficient of a colored liquid (a mixed color solution in which the first to n-th base inks are mixed) in the container of the printing unit 2a.

It is assumed that the difference between the absorption coefficients Ko and Kf at the optimum time and the failure judgment time is equal to the already calculated right side {(Ci × (K) i)} of the equation (3).
The following equation (4) is derived by substituting the left side of equation (3).

[0065]

(Equation 2)

Where Ko = Σ (Ci × (K) i) Kf = Σ (Ci × (K) i) ΔCi: ink addition amount The liquid monitor units 6a to 6d indicate the difference between the two absorption coefficients Ko and Kf. The left side of the equation (4) is calculated for each wavelength in the visible light region (ST14; blending change calculating means). As a result of the calculation,
If the left side of equation (4) has a negative wavelength, it is determined that the colored liquid is dark, and the colorless solution of the reducer is externally applied until the left side of equation (4) has a positive value in the entire visible light region. The coloring liquid is supplied from a piping system of a tank into a corresponding container of the printing unit 2a, for example, to dilute the coloring liquid.

Next, the liquid monitor units 6a to 6d use the least squares method and replace the left side of equation (4) with the right side of equation (4) ｛Σ (Δ
An additional amount ΔCi of each base ink is calculated so as to be equal to Ci × (K) i)｝ (ST15; means for calculating a change in the mixture).

Subsequently, the liquid monitor units 6a to 6d add the base ink to the printing units 2a to 2d from the piping system of the external tank in accordance with the additional amount ΔCi obtained by the least square method (ST16; mixing correction means). ).

As described above, by correcting the blending amount of the coloring liquid so that the absorption coefficient Kf of the coloring liquid in the printing units 2a to 2d at the time of the defect determination approaches the absorption coefficient Ko at the optimum time, the web printing sheet 4 is modified. The color fluctuation of the upper print color can be suppressed.

Next, a specific example of this embodiment will be described. For example, an aqueous gravure ink (yellow, red, indigo, reducer) for building materials manufactured by Polytex Co., Ltd. is adjusted to a viscosity of 13 seconds with a # 4 Zahn cup, and printing is started with an ink mixed in an appropriate amount. .

The arithmetic and control unit 7 periodically sends a colorimetric instruction to the liquid monitor units 6a to 6d and the printed matter monitor unit 5 at the same time. The liquid monitor units 6a to 6d change the printing ink A of the container to a visible light region of 400 nm to 70
At 0 nm, the print monitor 5 measures the color of the web print sheet 4 in the visible light range of 400 nm to 700 nm at intervals of 20 nm according to the color measurement instruction.

The spectral transmittance To (λ) of the printing ink A1 determined to be optimum at the time of printing at 300 m was obtained. Thereafter, a defect occurred at the time of printing at 1000 m. Since the spectral transmittance Tf (λ) of the ink A2 determined to be this defect was obtained, the color was corrected.

The liquid monitoring units 6a to 6d calculate the absorption coefficient Ko (λ) from the spectral transmittance To (λ) at the optimum time, and also determine the absorption coefficient Kf (λ) from the spectral transmittance Tf (λ) at the time of failure determination. And the difference between the two absorption coefficients for each wavelength ｛Ko
After calculating (λ) −Kf (λ)}, the additional amount ΔCi of the base ink is calculated.

Here, the spectral transmittances To (λ), Tf
(Λ), the absorption coefficients Ko (λ), Kf (λ), and the difference between the two absorption coefficients are as shown in FIG.

From the above measurement results, the additional amount ΔCi of the base ink was 0.84% for yellow, 0.74% for red, and 0.59 for indigo.
% And reducer 5%. The additional amount Δ
As a result of modifying the compounding amount of the coloring liquid based on Ci, the color fluctuation on the paper web print sheet 4 could be reduced.

In the same manner, by repeating such color correction at the time of failure determination, it is possible to suppress color fluctuation of the colored liquid during printing.

As described above, according to the present embodiment, the liquid monitor units 6a to 6d irradiate the printing ink A extracted from the container with light, measure the spectral characteristics of the transmitted light, and monitor the printed matter monitor unit 5. Measures the spectral reflectance of the printing ink A printed on the web printing sheet 4, and the arithmetic and control unit 7 calculates a color value from the spectral reflectance to determine whether there is a change in the color value, and Is determined to be present, the liquid monitor units 6a to 6d determine the additional amount ΔC of the mixing amount of the printing ink A in the container based on the change in the spectral transmittance T (λ).
i is calculated, and the base ink (colored liquid) or reducer (transparent liquid) is supplied into the container according to the additional amount ΔCi. Therefore, when the color change of the printed matter is detected, the compounding amount of the colored liquid is changed. The previous state can be corrected, and the quality of the printed matter can be improved.

In addition, in a toning method called computer color matching (CCM), which is well known in the art, the absorption coefficient (K) mix of the colored liquid of the printing unit is made to coincide with the absorption coefficient Ko of the target colored liquid. The amount Ci of each base ink is calculated in such a manner as to cause the above.

On the other hand, the present embodiment is an application of this CCM, and the absorption coefficient K of the colored liquid at the optimal point in time.
From the absorption coefficient (Ko-Kf) of the difference between o and the absorption coefficient Kf at the time of the defect determination, the addition amount ΔCi of the blending amount of the colored liquid is calculated using, for example, the least square method.

The liquid monitoring units 6a to 6b include:
Liquid having two transparent first and second flat glass portions 21 and 22 which are arranged to face each other and whose interval is adjustable, and which allows printing ink A to pass between each of the flat glass portions 21 and 22. Supply port 23a and liquid discharge port 23b
, A measuring cell having: a light incident on the printing ink A between the flat glass portions 21 and 22; and a transmission through the printing ink A when light is incident by the incident optical system. Spectrophotometer 31 for measuring the transmittance of light
The colored liquid with high transparency is measured by measuring the transmittance of transmitted light while preventing the coloring component from adhering to the measuring cell by passing the colored liquid through the measuring cell. Can also be applied.

Further, since the printing ink A of the ink pan 30a can be automatically supplied to the film forming apparatus 20 by the pump,
The color measurement can be performed on the site side without the need for manual operation, and the color measurement of the printing ink A can be performed stably with high accuracy because the manual operation is unnecessary.

The first and second flat glass portions 21 and
2 are brought into contact with each other to adjust the zero position and then form a fixed gap, thereby causing an error in film thickness control even when the relative positional relationship in the colorimetric cell changes with time. Therefore, the reliability of the film thickness control can be improved.

The first and second flat glass portions 21 and
As for 2, since the contact surfaces of each other are formed smoothly, the effects of the present embodiment can be achieved easily and reliably.

Further, the first and second flat glass portions 21,
22, housing glass 23 and piston glass 25
Is made of a transparent material such as quartz glass, synthetic quartz glass, or BK7 glass, so that the effects of the present embodiment can be easily and reliably achieved.

The first and second flat glass portions 21 and
2. Since the housing glass 23 and the piston glass 25 are provided with a water-repellent layer made of a fluororesin thin film on the surface in contact with the printing ink A, when measuring a colored liquid of a different color, the measurement is different from the conventional method. Cleaning for each color can be eliminated.

Further, since the fluid pressure cylinder is provided as the driving means, the effects of the present embodiment can be easily and reliably exhibited.

Further, when the position sensors 35a and 35b for detecting the lower limit position and the upper limit position of the upper and lower pistons 26 respectively are provided, the position of the upper and lower pistons 26 can be automatically regulated. Performance can be improved.

In the above embodiment, the liquid monitor 6
a to 6d have described the case where the addition amount ΔCi of the printing ink A is calculated to correct the mixing amount. However, the present invention is not limited to this, and the arithmetic control unit 7 calculates the additional amount ΔCi of the coloring liquid to correct the mixing amount. With this configuration, the same effect can be obtained by implementing the present invention in the same manner. That is, the data processing other than the measurement of the spectral characteristics such as the transmittance and the reflectance (color change determination unit, combination change calculation unit and combination correction unit) is performed by the liquid monitor units 6a to 6d, the print monitor unit 5, and the arithmetic control unit 7. And any modified configuration having the same operation and effect as a whole is included in the scope of the present invention.

Further, from the viewpoint of making the light uniform, the light source unit 3
A well-known integrating sphere (for example, Otsuka Electronics Co., Ltd.) is provided on the incident optical axis between the first flat glass part 6 and the first flat glass part 31 or on the transmitted optical axis between the second flat glass part 22 and the spectrophotometer 31. Even with the interposed structure, the present invention can be implemented in the same manner and have the same effects. The integrating sphere is preferably provided integrally with the container from the viewpoint of improving the colorimetric accuracy by taking in the transmitted light that has passed through the colored liquid while causing scattering, absorption, and the like, by 180 degrees.

Further, the case where the spectrophotometer 31 measures the spectral transmittance has been described, but the present invention is not limited to this.
The present invention can be implemented in the same manner as a configuration for measuring spectral characteristics such as spectral absorption intensity or spectral reflectance (in the case of spectral reflectance measurement, the spectrophotometer 31 and the light source unit 36 are arranged on the same side). The same effect can be obtained.

Further, the case where the spectrophotometer 31 is held in the piston glass 25 and the light source section 36 is disposed below the first flat glass section 21 has been described, but the present invention is not limited to this. Even if the arrangement with the part 36 is reversed, the present invention can be implemented in the same manner and the same effect can be obtained.

Further, the case where the spectrophotometer 31 and the light source unit 36 are arranged on different sides as viewed from the colored liquid and the transmitted light is measured has been described. Are arranged on the same side as viewed from the colored liquid, and the spectrophotometer 31 is modified to measure the reflected light from the colored liquid, the same effect can be obtained by implementing the present invention in the same manner. .

Further, a case has been described in which the colored liquid is sampled so as to be taken out of the ink pan 30a and measured outside the ink pan 30a. However, the present invention is not limited to this, and the colored liquid is sampled in the ink pan 30a and the colored liquid is sampled in the ink pan 30a. Even when the measurement is performed internally, the present invention can be implemented in the same manner and the same effect can be obtained.

In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0095]

As described above, according to the present invention, when the color change of the printed printed matter is detected, the compounding amount of the coloring liquid can be corrected to the state before the color change, and the quality of the printed matter can be improved. The obtained color correction device and color correction method can be provided.

Further, the present invention can be applied to a highly transparent colored liquid while preventing the coloring component from adhering to the measuring cell.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a printing system to which a color correction device according to an embodiment of the invention is applied.

FIG. 2 is a schematic diagram showing the concept of a print monitor in the embodiment.

FIG. 3 is a block diagram showing a configuration of a print monitor in the embodiment;

FIG. 4 is a schematic diagram showing a configuration of a liquid monitor unit according to the embodiment.

FIG. 5 is a flowchart for explaining the operation in the embodiment;

FIG. 6 is a view for explaining a change in color value in the embodiment.

FIG. 7 is a diagram showing a data table for explaining a specific example in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Paper feed part 2a-2d ... Printing unit 3 ... Cooling / web path part 4 ... Web print sheet 5 ... Printing part monitor part 6a-6d ... Liquid monitor part 7 ... Operation control part 8, 36 ... Light source part 9 ... Sensor DESCRIPTION OF SYMBOLS 10 ... Scanning part 11 ... Colorimetry part 12 ... Display part 13 ... Stabilization power supply 20 ... Film forming apparatus 21, 22 ... Flat glass part 23 ... Housing glass 23a ... Liquid supply port 23b ... Liquid discharge port 24 ... Piston case 24a, 26a ... convex part 24b ... opening part 24c, 24d ... communication port 25 ... piston glass 26 ... upper and lower piston 27 ... lid member 28a, 28b ... conduit 29a, 29b ... check valve 30a, 30b ... ink pan 31 ... spectrophotometer 32 ... Computer 33: fluid pressure source 34a, 34b: solenoid valve 35a, 35b: position sensor A: printing ink

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Inamura 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F-term (reference) 2C061 AS05 KK04 KK13 KK22 KK32 2C250 EA23 EB32 2G020 AA08 DA02 DA03 DA04 DA12 DA21 DA43 DA62 DA65 5C074 AA07 AA10 BB19 DD21 DD27 EE01 EE11 FF15 GG01 HH04

Claims (3)

[Claims] 1. A color correcting apparatus for correcting a color of a coloring liquid on a printing sheet to a constant value when repeatedly printing a coloring liquid contained in a container on a printing sheet supplied continuously. A liquid monitor unit that samples the colored liquid in the container, irradiates the colored liquid with light as it is, and measures the spectral characteristics of reflected or transmitted light, and spectral analysis of the colored liquid printed on the printing sheet. A print monitor that measures reflectance, a color change calculator that calculates a color value from the spectral reflectance measured by the print monitor, and determines whether or not the color value has changed based on the calculation result. When the color change determination unit determines that the color value has changed, the amount of change in the blending amount of the colored liquid in the container is calculated based on the change in the spectral characteristics measured by the liquid monitor unit. A combination change calculating unit that performs a color change or a transparent liquid supply into the container so as to correct the change amount calculated by the mix change calculation unit to zero. Correction device. 2. The color correction device according to claim 1, wherein the liquid monitor section includes two transparent parallel flat plates that are arranged to face each other and that can be adjusted at an interval, and the liquid monitor section is disposed between the parallel flat plates. A measuring cell having a liquid supply port and a liquid discharge port for passing the colored liquid, an incident optical system for incident light on the colored liquid between the parallel flat plates, and light incident by the incident optical system And a spectrophotometer for measuring the transmittance of transmitted light that passes through the colored liquid between the parallel flat plates. 3. A color correction method for correcting a color of a coloring liquid on a printing sheet to a constant value when repeatedly printing a coloring liquid contained in a container on a continuously supplied printing sheet. A liquid monitoring step of sampling the colored liquid in the container, irradiating the colored liquid with light as it is, and measuring the spectral characteristics of reflected or transmitted light, and spectral analysis of the colored liquid printed on the printing sheet. A printed matter monitoring step of measuring the reflectance, a color value is calculated from the spectral reflectance measured by the printed matter monitoring step, and a color change determination step of determining whether or not the color value has changed based on the calculation result. When it is determined in the color change determination step that the color value has changed, a change in the blending amount of the coloring liquid in the container is performed based on the change in the spectral characteristics measured in the liquid monitoring step. A compound change calculating step of calculating the amount, and a compound correcting step of supplying a colored liquid or a transparent liquid into the container so as to correct the change amount calculated in the compound change calculating step to zero. Characteristic color correction method.