JPH10213481A - Liquid color measuring device and method for correcting color of colored liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain accurately an additional amount of a color material for color correction and perform correct color correction even in the case of colored liquid having the high permeability. SOLUTION: A liquid color measuring device 2 is provided with a tank 8 having first and second opposed transparent tank walls 4, 6 to accommodate ink. A light ray is incident on the tank 8 through a light guide 48 from outside the first tank wall 4 and into an integrating sphere 52 through the first and second tank walls 4, 6 and the ink between the tank walls. Thereafter, the light ray is supplied through an exit opening 56 to the measuring means for transmission factor. The first tank wall 4 is moved vertically through a drive rod 16 so that a proper amount of light rays can be supplied to the measuring means according to the density of the ink by varying an interval between the tank walls. Also, the light rays scattered in the various directions in the ink within the tank 8 are collected by the integrating sphere 52 to be supplied to the measuring means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus capable of measuring the color of a coloring liquid such as ink, and using the result obtained by the color measurement for correcting the color of the coloring liquid such as ink. It relates to a method for correcting the color of a liquid.

[0002]

2. Description of the Related Art Conventionally, for example, in color printing, an ink (coloring liquid) used for printing is generated by previously blending a plurality of color materials having different colors so as to obtain a target color. By the way, the color of the ink gradually becomes different from the color at the start of printing due to a change over time as the printing operation progresses. Therefore, conventionally, as color management, the color obtained at the start of printing is compared with the color after a certain amount of time by visually observing or measuring the color of the printed matter obtained as a result of printing, and the color The color of the ink was corrected by adding materials to the ink.

[0003] As a method of comparing colors for such color correction, besides comparing colors of printed matter visually or by colorimetry, a color liquid at the start of printing and a color liquid after a certain period of time have elapsed. A method has also been attempted in which each sample is sampled and colorimetry is performed in a liquid state. This method is described in, for example,
It is disclosed in JP-A-1-56923 and JP-A-61-65123, in which a light guide is immersed in a coloring liquid to measure the color of the coloring liquid. Also, Japanese Patent Application Laid-Open No. 6-508
No. 19 discloses that, in the case of a paint having a low light transmittance (that is, a high concealing property), light is incident on the liquid surface at a predetermined angle, and light reflected in a vertical direction is detected by a color sensor. A colorimetric method is disclosed. However, in the above-described method of comparing the colors of the printing result by visual observation or colorimetry, it is possible to directly know only the color difference in the printed matter, not the color material amount itself. Therefore, the amount of color material to be added for color correction is calculated from the color difference in the printed matter, and the relationship between the added amount of color material and the amount of color change on the printed matter is accurately determined. You have to know. However, it is usually difficult to accurately grasp this relationship.

Further, in the above-described method of comparing colors in the state of the colored liquid, the cell containing the colored liquid of the sample cannot be quickly washed, so that the colored component remains fixed on the glass surface of the cell, and the previous colorimetry is performed. Accurate colorimetry is difficult due to the influence of light. Furthermore, in this method, a wiping device is required to remove the coloring liquid adhering to the detection probe of the color sensor, and there is a high possibility that the tip of the probe is damaged by wiping repeatedly for each color measurement. In the method of measuring the color by the reflected light, it is difficult to accurately correct the color when a coloring liquid having a high light transmittance (that is, a low concealing property) such as gravure ink is used.

That is, in the case of a colored liquid having a high concealing property,
Since the color in the state of being applied on a support such as paper and the color in the liquid state match, the color measured by reflected light in the liquid state becomes the color in the printed matter, but it is hidden like gravure ink etc. In the case of a colored liquid with low properties, the color of the state applied on the support is strongly affected by the color of the support,
The color measured by the reflected light in the liquid state is different from the color in the actual printed matter. In addition, in addition to ink as a coloring liquid for printing, a paint, a coloring solution of plastic, or the like is used, but the same problem occurs in such a case.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to perform colorimetry with high accuracy by using a colored liquid as a liquid and with a spectral transmittance, and to provide a color material for color correction. Color liquid that can accurately determine the required additional amount and that can correct the color correctly even in the case of a colored liquid with high light transmission, and that can efficiently solve these problems. And a liquid color measuring device.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is an apparatus for measuring the spectral transmittance of light transmitted through a coloring liquid, wherein the transparent first and second tank walls are opposed to each other. A tank for storing the coloring liquid, a light source for irradiating the coloring liquid in the tank with light from outside the first tank wall, and a light transmitting the coloring liquid to the second tank wall. And a transmittance measuring means for measuring the spectral transmittance.
At least one of the first and second tank walls is disposed so as to be movable in a direction approaching or separating from the other.

The present invention is also directed to a driving means for driving at least one of the first and second tank walls, and receiving light transmitted through the coloring liquid through the second tank wall to measure the amount of light. And a control unit for controlling the driving unit such that the light amount measured by the light amount measurement unit becomes a predetermined light amount.
The present invention further includes an integrating sphere disposed outside the second tank wall and close to the second tank wall, and collecting light transmitted through the coloring liquid and emitting the light to the transmittance measuring means. It is characterized by having. The present invention also includes first and second storage tanks for storing first and second coloring liquids, respectively, and first and second tanks for supplying the coloring liquid from the first and second storage tanks to the tank. A liquid supply unit for discharging the coloring liquid in the tank to the outside of the tank. The present invention is further characterized by further comprising a third storage tank for storing the solvent, and third liquid supply means for supplying the solvent from the third storage tank to the tank. The present invention is also characterized in that the coloring liquid is a printing ink. The present invention is also preferably characterized in that the ink is a highly transparent ink, and more preferably, the highly transparent printing ink is a gravure ink.

The present invention also relates to a method for correcting the color of a coloring liquid produced by mixing a plurality of coloring materials having different colors, wherein the coloring liquid is irradiated with light, and the light transmitted through the coloring liquid is irradiated with light. The spectral transmittance is measured, and the mixing ratio of the coloring material is corrected based on the measured spectral transmittance. The present invention is also characterized in that the colored liquid is irradiated with light using the liquid color measuring apparatus of the present invention, and the spectral transmittance of the light transmitted through the colored liquid is measured. The present invention is also characterized in that the coloring liquid is a printing ink. The present invention also measures the first spectral transmittance at the start of printing, and measures the second spectral transmittance at a point in time when a certain period of time has elapsed since the start of printing. The mixing ratio of the coloring material is corrected so as to match the first spectral transmittance. The present invention is also preferably characterized in that the ink is a highly transparent ink, and more preferably, the highly transparent printing ink is a gravure ink.

[0010] In the liquid colorimeter of the present invention, the tank has transparent first and second tank walls opposed to each other and stores the colored liquid, and the light source is provided inside the tank from outside the first tank wall. The colored liquid is irradiated with light. The transmittance measuring means receives the light transmitted through the coloring liquid through the second tank wall and measures the spectral transmittance of the light.
And since at least one of the first and second tank walls is movable in a direction approaching or separating from the other, the first and second tanks are provided when the concentration of the coloring liquid is high. The distance between the walls can be set to be small, and conversely, if the concentration of the coloring liquid is low, the distance between the first and second tank walls can be set to be wide. Therefore, an appropriate amount of light can be made incident on the measuring means irrespective of the concentration of the coloring liquid, and the spectral transmittance can always be measured with good accuracy.

Further, by setting the distance between the first and second tank walls narrow, it is possible to measure the spectral transmittance even in the case of a colored liquid having a low transmittance, that is, a high concealing property. That is, it is possible to measure the spectral transmittance of various coloring liquids from a coloring liquid having a high transmittance to a coloring liquid having a low permeability. Further, since the coloring liquid to be measured is merely supplied into the tank, the switching of the coloring liquid is easy. In addition, the inside of the tank can be easily cleaned by flowing the solvent through the tank. Further, since it is not necessary to immerse the probe in the coloring liquid as in the related art, there is no problem that the probe is damaged due to cleaning of the probe. Further, in the liquid color measurement device of the present invention, the integrating sphere arranged outside the second tank wall and close to the second tank wall collects light transmitted through the colored liquid and supplies the light to the transmittance measuring means. Therefore, the measurement can be performed not only of the light transmitted straight through the coloring liquid but also the light scattered variously in the coloring liquid. When the coloring liquid is, for example, ink, when the ink is actually applied on a support such as paper, light scattered in the coloring liquid enters human eyes. Thereby, it is possible to perform the measurement under conditions close to the actual state.

In the method for correcting the color of a colored liquid according to the present invention, the colored liquid is irradiated with light, the spectral transmittance of the light transmitted through the colored liquid is measured, and the colorant is mixed based on the measured spectral transmittance. Modify rate. That is, since the color measurement is performed by the transmitted light of the coloring liquid, instead of performing the color measurement or the like in a state of being once printed or coated on paper or the like as in the related art, the change in the mixing ratio of each color material is estimated. The change in the mixing ratio of each color material forming the color can be directly obtained in a liquid state without printing or coating, and thus accurate color correction is possible.
Then, even in the case of a coloring liquid having a high transparency such as gravure ink, the color can be corrected correctly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of an example of a liquid color measurement device according to the present invention, and FIG. 2 is a functional block diagram of this embodiment. As shown in these figures, the liquid colorimeter 2 of the present embodiment has a transparent first
And a tank 8 having second tank walls 4 and 6 for storing ink as a coloring liquid, a light source 10 for irradiating the coloring liquid in the tank 8 with light from outside the first tank wall 4, Measuring means 12 for receiving the light transmitted through the liquid through the second tank wall 6 and measuring the spectral transmittance of the light is provided.

The side wall of the tank 8 is formed by a cylindrical body 14 having a circular cross section, and the first and second tank walls 4, 6 having a circular shape in a plan view are in parallel with each other, and are several μm in the present embodiment between them. The plate surface is arranged in the cylinder 14 at an interval of several tens μm from the direction of the right angle to the direction in which the cylinder 14 extends. The outer peripheral end surface of the second tank wall 6 is in close contact with the inner surface of the cylindrical body 14 so that the cylindrical body 14
On the other hand, the first tank wall 4 is arranged in a vertical direction as indicated by an arrow D, that is, in a direction in which the cylindrical body 14 extends, in a state where the outer peripheral end surface is in close contact with the inner surface of the cylindrical body 14. It is slidable. A drive rod 16 is erected near the center of the upper surface of the first tank wall 4.
Is connected to a stepping motor (not shown) via power transmission means including a nut and a ball screw. The driving means 18 is constituted by the driving rod 16, the power transmission means, and the stepping motor.
By this driving means 18, the position of the first tank wall 4 is controlled with an accuracy of moving about 1 μm at most when one pulse is input to the stepping motor.

The first tank wall 4 also has an ink supply port 2.
0 is formed, and the supply port 20 is connected through a pipe 22 to a first storage tank 24 for storing the ink A, a second storage tank 26 for storing the ink B, and a second storage tank 26 for storing the solvent C. 3 storage tanks 28. Solenoid valves 30 for controlling the supply of ink and solvent are provided at the outlets of the first to third storage tanks 24, 26, 28, respectively.
32, 34, and pumps 36, 38, 40 (first to third liquid supply means according to the present invention) for delivering ink and solvent to the pipe 22 are provided. An ink outlet 42 is provided at a position between the first tank wall 4 and the second tank wall 6 of the cylindrical body 14, and the outlet 42 is connected to a discharge pipe 46 through a discharge valve 44. ing. The discharge port 42 and the discharge valve 44 constitute a liquid discharge unit according to the present invention. In this embodiment, the light source 10 includes a halogen lamp (not shown) and a light guide 48 made of an optical fiber. The end 50 of the light guide 48 is fixed to the center of the upper surface of the first tank wall 4. The light exits from the end 50 of the light guide 48 substantially perpendicularly to the first tank wall 4 and enters the tank 8 through the first tank wall 4.

An integrating sphere 52 is provided below the second tank wall 6 of the tank 8.
Is arranged. An entrance aperture 54 is provided above the integrating sphere 52.
Is formed, and the integrating sphere 52 is positioned so that the entrance opening 54 is in contact with the lower surface of the second tank wall 6, and is positioned so as to face the end 50 of the light guide 48 with the tank 8 interposed therebetween. ing. An exit opening 56 is formed on the side of the integrating sphere 52, and light incident into the integrating sphere 52 exits the integrating sphere 52 through the exit opening 56, and
The light enters the measuring means 12. The measuring means 12 (omitted in FIG. 1) is arranged close to the exit aperture 56 of the integrating sphere 52. In the present embodiment, the measuring means 12 has a photomultiplier as the light quantity measuring means 58, and has a grating as the transmittance measuring means 60. , A CCD array and the like. In this embodiment, the transmittance measuring means 60 of the measuring means 12 is 400
In the wavelength range of nm to 700 nm, the transmittance is obtained every 20 nm, and an electric signal representing the transmittance for each wavelength is output. Further, the light quantity measuring means 58 outputs a signal indicating the transmitted light quantity. The control operation means 61 (omitted in FIG. 1) is specifically constituted by a personal computer having a hard disk or a CRT monitor in the present embodiment.
The absorption coefficient of the ink is obtained based on the signal indicating the transmittance output from the transmittance measuring means 60 of FIG. Further, the control calculation means 61 controls the driving means 18 based on the signal indicating the transmitted light quantity output from the light quantity measurement means 58 of the measurement means 12 to adjust the interval between the first and second tank walls 4, 6. And
When the measurement of the spectral transmittance is started, the amount of light incident on the transmittance measuring means 60 is set to a predetermined value suitable for measuring the spectral transmittance. The control calculation means 61 also controls the solenoid valve 3
0, 32, 34 and pumps 36, 38, 40 to control the supply of ink and solvent.
On / off control.

Next, the measurement of the spectral transmittance by the liquid colorimeter 2 of the present embodiment configured as described above will be described.
An embodiment of the method for correcting the color of a colored liquid according to the present invention will be described. Here, the ink is gravure ink, the ink at the start of printing is stored in the first storage tank 24 as ink A, and the ink after a certain period of time from the start of printing is ink B. It is to be stored in the second storage tank 26.

By performing a predetermined operation for starting the measurement on the control calculation means 61, the control calculation means 61 starts the operation. First, the light source 10 is turned on and turned on, and the solenoid valve 30 is opened. At the same time, the pump 36 is started. Thereby, the ink A is supplied from the first storage tank 24 into the tank 8 through the pipe 22, flows through the tank 8 while filling the tank 8, and is discharged from the discharge port 42. Here, by setting the discharge valve 44 to an appropriate opening, the ink in the tank 8 is appropriately pressurized, and as a result, the bubbles in the tank 8 are effectively removed. In this initial state, the distance between the first and second tank walls 4 and 6 is about 10 μm in this embodiment.

Light emitted from the halogen lamp of the light source 10 is guided to the tank 8 by the light guide 48,
Through the ink filling the tank walls 4 and 6 and the tank 8, the light enters the integrating sphere 52 from the entrance opening 54. The transmitted light collected in the integrating sphere 52 exits from the exit aperture 56 and enters the measuring means 12. The light incident on the measuring means 12 is received by the light quantity measuring means 58 and the light quantity measuring means 5
Reference numeral 8 outputs a signal representing the amount of transmitted light. Control calculation means 61
Based on this signal, first, the distance between the first and second tank walls 4 and 6 is adjusted. That is, the control operation means 61
Is the distance between the first and second tank walls 4 and 6 necessary to make the transmitted light amount of the light passing through the tank 8 an appropriate value based on the transmitted light amount indicated by the signal from the light amount measuring means 58. Then, a control pulse is outputted so that the stepping motor of the driving means 18 is rotated so that the first and second tank walls 4 and 6 are at the same interval, and the first and second tank walls 4 and 6 are driven through the driving rod 16. The tank wall 4 is moved upward or downward. The density of ink used for printing varies, and the range of density is extremely wide. Therefore, by performing such adjustment of the tank wall interval, light of an amount of light suitable for measuring the spectral transmittance is always supplied to the transmittance measuring unit 60 of the measuring unit 12 for any concentration of ink. And stable and good measurement accuracy can be secured.

As described above, the first and second tank walls 4, 6
Is adjusted, the light from the light guide 48 passes through the first and second tank walls 4, 6 and the ink filled between the tank walls, and passes through the integrating sphere 52 to the measuring means 1.
2, the transmittance measuring means 60 of the measuring means 12
Calculates the transmittance for every 20 nm in the wavelength range of 400 nm to 700 nm from the incident light, and outputs an electric signal indicating the transmittance for each wavelength. The control calculation means 61 receives the electric signal indicating the transmittance for each wavelength, and calculates the absorption coefficient for the light of the ink based on the signal as follows. Generally, it is known that the following relationship exists between the light absorption coefficient K and the transmission coefficient T of a highly transparent liquid such as gravure ink.

[0021]

K = -ln (T) / X Here, X is a light passage distance, which corresponds to the distance between the first and second tank walls 4 and 6 in the liquid colorimeter 2, and is therefore constant. It may be a value, and therefore [Equation 1] is equivalent to the following equation.

[0022]

K = -ln (T) That is, the control calculation means 61 calculates an absorption coefficient for each wavelength based on [Equation 2]. Control calculation means 6
Reference numeral 1 temporarily stores the absorption coefficient calculated in this way in a storage device such as a hard disk. Thereafter, in order to prepare for the next measurement, the control calculation means 61 stops the pump 36 and closes the solenoid valve 30, opens the solenoid valve 34, and operates the pump 40. As a result, the colorless and transparent solvent in the third storage tank 28 is fed and supplied into the tank 8 through the pipe 22, and the solvent is appropriately pressurized.
By flowing through the inside, the inside of the tank 8 is washed, and the ink A introduced into the tank 8 for measurement is completely removed from the tank 8. When the cleaning is completed, the control calculation means 61
0 is stopped, and the solenoid valve 34 is closed.

Thereafter, printing is performed with the ink A for a certain period of time, and the ink at the time of printing, for example, about 1000 m is stored as the ink B in the second storage tank 26. Then, the control calculation means 61 opens the electromagnetic valve 32 and operates the pump 38 to supply the ink B into the tank 8. At this time, since the solvent used for cleaning may remain in the tank 8, the ink B
After the ink B is filled with the ink B, the ink B
Fluid through. Then, as in the case of ink A,
Light from the light guide 48 is applied to the first and second tank walls 4,
6 and the ink B filled between the tank walls, penetrates the measuring means 12 through the integrating sphere 52, and the transmittance measuring means 60 of the measuring means 12
In the wavelength range of nm to 700 nm, the transmittance is obtained every 20 nm, and an electric signal representing the transmittance for each wavelength is output.

The control calculating means 61 receives the electric signal indicating the transmittance for each wavelength, and calculates the absorption coefficient of the ink with respect to the light according to the above [Equation 2] based on the signal. That is, the control calculation means 61 calculates
Then, the absorption coefficient is calculated for each wavelength, and the calculated absorption coefficient is temporarily stored and held in a storage device such as a hard disk. [Table 1] below shows an example of the spectral transmittance measured by the transmittance measuring unit 60 and the absorption coefficient of each ink determined by the control calculation unit 61 based on the spectral transmittance.

[0025]

[Table 1]

FIG. 3 is a graph plotting the spectral transmittance of [Table 1], and FIG. 4 is a graph plotting the absorption coefficient of [Table 1]. 3 and 4, the horizontal axis of the graph represents the wavelength, and the vertical axis represents the transmittance and the absorption coefficient, respectively. Also, curves 62 and 6 in FIG.
4 indicates the spectral transmittance of the inks A and B, respectively, and the curves 66 and 68 in FIG. 3 indicate the absorption coefficients of the inks A and B, respectively.

In the measurement, an integrating sphere 52 manufactured by Otsuka Electronics Co., Ltd. was used, and a transmittance measuring means 60 was a spectrophotometer of Hamamatsu Photonics. The halogen lamp of the light source 10 was 100 watts. And
As the gravure ink, a water-based gravure ink (yellow, red, indigo, solvent) for building materials manufactured by Polytex was used.
The viscosity was adjusted with a Zahn cup of No. 3 to 28 seconds, and an appropriate amount of color was mixed to obtain ink A. And ink A
And printing was started, and thereafter, the ink at the time of printing 1000 m was designated as ink B. Next, the control calculation means 61 calculates the additional amount of the coloring material as follows based on the absorption coefficient for each wavelength of the inks A and B stored in the storage device. The absorption coefficient of a colored liquid formed by mixing a plurality of color materials with respect to light of a certain wavelength can be obtained by adding all the values obtained by multiplying the mixing ratio and the absorption coefficient for each color material. Therefore, the absorption coefficient (K) mixa of the ink A with respect to light of a certain wavelength is represented by Cia and (k) i where the mixing ratio and the absorption coefficient of the i-th color material are Cia and (k) i, respectively.

[0028]

## EQU3 ## (k) mixa = Σ (Cia * (K) i), and the absorption coefficient (K) mixb of the ink B with respect to light of a certain wavelength is given by the mixing ratio of the i-th color material as Cib.

[0029]

## EQU4 ## (k) mixb = Σ (Cib * (K) i). Therefore, the difference between the two absorption rates is as follows.

[0030]

## EQU5 ## (k) mixa- (k) mixb = Σ ((Ci
a-Cib) * (K) i) The left side of this equation is the difference between the absorption coefficients of ink A and ink B, and the absorption coefficient of each ink is stored in the storage device. The absorption coefficient (K) i of each color material on the right side is also known. Therefore, the difference Cia-Cib of the mixing ratio of each color material in the ink A and the ink B can be obtained from this formula, and based on the result, the color is corrected by adding each color material to eliminate the difference in the mixing ratio. can do.

Therefore, the control calculation means 61 first reads out the absorption coefficient for each wavelength of the inks A and B from the storage device, and calculates the difference between the absorption coefficients for each wavelength. And
Using the absorption coefficient of each color material held in advance, the difference Cia-Cib of the mixing ratio of each color material such that [Equation 5] is established as accurately as possible at all the wavelengths at which the measurement was performed, using the least squares method. Ask. Then, the control calculation means 61 displays the calculated difference Cia-Cib of the mixing ratio of each color material on the CRT monitor as a ratio of adding each color material.
The operator can add each color material according to the displayed numerical value and correct the color of the ink. If the left side is negative in [Equation 5], the ink B has a higher absorption coefficient, and it is necessary to remove the coloring material to correct the color. However, since this is practically impossible, in this case, a colorless and transparent solvent is additionally mixed with the ink B to dilute it, and the spectral transmittance is measured again to obtain the absorption coefficient of the ink B. With the left side not being negative in [Equation 5], the difference in the mixing ratio is determined. Then, at the time of color correction, at the same time as adding a color material, ink B
The solvent is mixed in the same ratio as when diluted.

In the case of the actual measurement results shown in [Table 1],
The rate of addition of each color material obtained by the control operation means 61 in the above-described procedure was 0.84% for yellow, 0.74% for red, and 0.59% for indigo. The rate of addition of the solvent was 5%. Such color materials are added at regular intervals (for example, 10
(Every time printing is performed for the length of 100 m), the color fluctuation of the coloring liquid during printing can be suppressed, and the color of the printed matter can be stabilized.

In this embodiment, as an example, the absorption coefficient of the ink is calculated once from the measured spectral transmittance, and the additional ratio of each color material is calculated based on the absorption coefficient.
It is also possible to more directly determine the additional ratio of each color material required for color correction based on the spectral transmittance of light passing through the inks A and B. Also, as is apparent from [Equation 1], since the spectral transmittance and the absorption coefficient correspond one-to-one, the absorption coefficient of each color material is adjusted so that the absorption coefficient of ink B matches the absorption coefficient of ink A. Correcting the mixing ratio is the same as correcting the mixing ratio of each color material so that the transmittance of light passing through ink B matches the transmittance of light passing through ink A.

As described above, in the method for correcting the color of the coloring liquid of this embodiment, the color is measured by the transmitted light of the ink. Instead of estimating the change in the mixing ratio of the materials, the change in the mixing ratio of each color material of the ink can be directly obtained, and thus accurate color correction is possible. Then, even in the case of a coloring liquid having a high transparency such as gravure ink, the color can be corrected correctly. Further, in the liquid colorimeter 2 of the present embodiment, the first tank wall 4 is movable and the light passage distance is variable. Therefore, when the concentration of the coloring liquid is high, the first and second tank walls are required. Is set to be small, and conversely,
When the concentration of the coloring liquid is low, the distance between the first and second tank walls can be set wide. Therefore, an appropriate amount of light can be made incident on the measuring means irrespective of the concentration of the coloring liquid, and the spectral transmittance can always be measured with good accuracy.

By setting the distance between the first and second tank walls 4 and 6 to be small, not only a liquid having a high transparency such as gravure ink but also a liquid having a low transparency, that is, a concealing property can be obtained. It is possible to measure the spectral transmittance even with a high colored liquid. That is, it is possible to measure the spectral transmittance of a variety of coloring liquids from a coloring liquid having a high transmittance to a coloring liquid having a low transmittance, and perform color correction. In addition, the integrating sphere 5
2, the transmitted light is collected, so that it is possible to measure not only the light transmitted straight through the ink but also the light scattered variously in the ink. In the state where the ink is actually applied on the support, the light scattered in the ink enters the human eye, so that the measurement can be performed under conditions close to the actual state by using the integrating sphere 52. It has become. Further, since the ink to be measured is merely supplied into the tank 8, the ink can be easily switched. In addition, the inside of the tank 8 can be easily cleaned by flowing the solvent through the tank 8. Further, since it is not necessary to immerse the probe in the ink as in the related art, there is no problem that the probe is damaged due to the cleaning of the probe.

The first and second storage tanks 24, 26
By providing a piping device or the like for supplying a color material to the apparatus, it is possible to achieve more efficient measurement. In the above embodiment, the driving rod is driven by the driving means 18 including a nut and a ball screw.
It is of course possible to use a pinion rack mechanism or the like. Further, the light source 10 may be a tungsten lamp, a xenon lamp, an ultra-high pressure mercury lamp, or the like, instead of a halogen lamp. Further, the transmittance measuring means 60
Can be configured using a filter and a CCD array. The measurement accuracy required for colorimetry should be appropriately determined according to the purpose of colorimetry and the like. But,
In a field where strict requirements are made for color adjustment, for example, when colorimetry is performed for color adjustment of ink in printing, the following point is one important point. In other words, the control of the interval between the inside of the first and second tank walls 4 and 6, which is a constituent element of the tank for accommodating the colored liquid in the form of a liquid film as a colorimetric sample, is performed with high measurement accuracy in colorimetry. It has a significant effect. The measurement sensitivity of the spectral transmittance changes depending on this interval. Therefore, in order to obtain a preferable measurement accuracy, it is preferable that the accuracy of the interval adjustment is at least about 1 μm as in the above-described embodiment. In particular, when it is desired to perform the measurement with high accuracy, the adjustment is performed with a fine scale of less than 1 μm. Use what is possible. If the accuracy of the interval adjustment is inferior, the measurement error related to colorimetry will increase, but if the accuracy of the interval adjustment is inferior to 1 μm, in the case of the printing ink, the measurement error is practically remarkable. Occurs.

[0037]

As described above, in the liquid color measuring device of the present invention, the tank has the transparent first and second tank walls facing each other and contains the colored liquid, and the light source is the first light source. The colored liquid in the tank is irradiated with light from outside the tank wall. The transmittance measuring means receives the light transmitted through the coloring liquid through the second tank wall and measures the spectral transmittance of the light. And since at least one of the first and second tank walls is movable in a direction approaching or separating from the other, the first and second tanks are provided when the concentration of the coloring liquid is high. The distance between the walls can be set to be small, and conversely, if the concentration of the coloring liquid is low, the distance between the first and second tank walls can be set to be wide. Therefore, an appropriate amount of light can be made incident on the measuring means irrespective of the concentration of the coloring liquid, and the spectral transmittance can always be measured with good accuracy. Further, by setting the distance between the first and second tank walls to be narrow, it is possible to measure the spectral transmittance even in the case of a colored liquid having a low transmittance, that is, a high concealing property. That is, it is possible to measure the spectral transmittance of various coloring liquids from a coloring liquid having a high transmittance to a coloring liquid having a low permeability.

Further, since the color liquid to be measured is merely supplied into the tank, it is easy to switch the color liquid. In addition, the inside of the tank can be easily cleaned by flowing the solvent through the tank. Further, since it is not necessary to immerse the probe in the coloring liquid as in the related art, there is no problem that the probe is damaged due to cleaning of the probe. Further, in the liquid colorimeter according to the present invention, the integrating sphere arranged outside the second tank wall and close to the second tank wall collects light transmitted through the colored liquid and emits the light to the transmittance measuring means. Therefore, the measurement can be performed not only of the light transmitted straight through the coloring liquid but also the light scattered variously in the coloring liquid. In the case where the coloring liquid is, for example, ink, the light scattered in the coloring liquid enters the human eye when the ink is actually applied on a support such as paper. It is possible to measure under close conditions. In the method for correcting the color of a colored liquid according to the present invention, the colored liquid is irradiated with light, the spectral transmittance of the light transmitted through the colored liquid is measured, and the mixing ratio of the coloring material is corrected based on the measured spectral transmittance. I do. That is, since the color measurement is performed by the transmitted light of the coloring liquid, the color liquid is formed instead of estimating the change in the mixing ratio of each color material by performing the color measurement or the like while printing on paper or the like as in the related art. The change in the mixing ratio of each color material can be directly obtained, and thus accurate color correction is possible. Then, even in the case of a coloring liquid having a high transparency such as gravure ink, the color can be corrected correctly.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a main part of an example of a liquid color measurement device according to the present invention.

FIG. 2 is a functional block diagram of the embodiment.

FIG. 3 is a graph in which the spectral transmittances of [Table 1] are plotted.

FIG. 4 is a graph in which the absorption coefficients in [Table 1] are plotted.

[Explanation of symbols]

 2 liquid colorimeter 4 first tank wall 6 second tank wall 8 tank 10 light source 12 measuring means 18 driving means 20 supply port 24 first storage tank 26 second storage tank 28 third storage tank 30, 32, 34 solenoid valve 36, 38, 40 pump 42 outlet 48 light guide 52 integrating sphere 60 transmittance measuring means 61 control computing means

Claims (10)

[Claims] 1. An apparatus for measuring a spectral transmittance of light transmitted through a coloring liquid, comprising: a tank having opposed transparent first and second tank walls for containing the coloring liquid; A light source for irradiating the colored liquid in the tank with light from outside the first tank wall; and a transmittance measuring means for receiving the light transmitted through the colored liquid through the second tank wall and measuring a spectral transmittance. Wherein at least one of the first and second tank walls is arranged to be movable in a direction approaching or separating from the other. 2. A light source for driving at least one of the first and second tank walls, and a light amount measuring device for receiving light transmitted through the coloring liquid through the second tank wall and measuring a light amount. 2. The liquid colorimetric device according to claim 1, further comprising: means; and control means for controlling the driving means such that the light quantity measured by the light quantity measuring means becomes a predetermined light quantity. 3. An integrating sphere disposed outside of the second tank wall and close to the second tank wall, for collecting light transmitted through the coloring liquid and emitting the light to the transmittance measuring means. The liquid color measurement device according to claim 1. 4. A first and second storage tank for storing first and second coloring liquids, respectively, and a first and a second tank for supplying the coloring liquid from the first and second storage tanks to the tank. 2. The liquid colorimetric device according to claim 1, further comprising: a second liquid supply unit; and a liquid discharge unit configured to discharge the coloring liquid in the tank to outside the tank. 3. 5. The liquid colorimetric apparatus according to claim 4, further comprising a third storage tank for storing the solvent, and third liquid supply means for supplying the solvent from the third storage tank to the tank. . 6. The liquid colorimeter according to claim 1, wherein the coloring liquid is a printing ink. 7. A method for correcting the color of a coloring liquid produced by mixing a plurality of coloring materials having different colors, comprising irradiating the coloring liquid with light, and spectral transmittance of light transmitted through the coloring liquid. And correcting the mixing ratio of the coloring material based on the measured spectral transmittance. 8. The liquid color measurement device according to claim 1, wherein the liquid is irradiated with light, and the spectral transmittance of the light transmitted through the color liquid is measured. The method for correcting the color of the coloring liquid described above. 9. The method according to claim 7, wherein the coloring liquid is a printing ink. 10. A first spectral transmittance is measured at the start of printing, and a second spectral transmittance is measured at a point in time when a certain period of time has elapsed since printing was started. First
10. The color correction method for a coloring liquid according to claim 9, wherein the mixing ratio of the coloring material is corrected so as to match the spectral transmittance of the coloring liquid.