JPS61192585A - How to record color images - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of recording a color image using a combination of a plurality of color inks by an inkjet recording method using a plurality of color inks.

[Conventional technology]

Three primary colors, cyan (C), magenta (M), and yellow (Y), are generally used as primary colors for forming a color image by the subtractive color mixing method. The colors that can be expressed by mixing and recording these three primary colors on the same pixel are basically the following four colors.

C+M-B (Blue) c+Y4G (Green) rvt+y→R (Red) C+M+Y-+K (Black) Therefore, the colors expressed by the three primary colors C, M, and Y are basically C, M, Y, R, There are seven colors, G, B, and K, and a multicolor image made up of these seven colors is called a false color image.

This method of forming false color images has conventionally been adopted in fields such as color offset printing, but recently it has been adopted in the field of color offset printing, etc., but recently it has been used in the field of infusiera and recording methods.

It is also used in thermal transfer recording methods, color LBP (laser beam printer) recording methods, etc.

When forming a false color image using the three primary colors C, M, and Y, the order in which these primary colors are recorded is as follows.

There are six types: C-+M-Y CY-M MC, Y MY-Y, CY-C→MY-+M+C. In fields such as offset printing, it is known that the recording order of primary colors affects color reproducibility, mainly due to the so-called trapping phenomenon in which the afterprinting ink is insufficiently coated on the preprinting ink.

[Problem that the invention seeks to solve]

An object of the present invention is to record a color image using a plurality of color inks by an inkjet recording method.
It is an object of the present invention to provide a recording method capable of obtaining precise and clear color images without causing color unevenness or image disturbance due to multiple recording.

[Means for solving problems]

The objects set forth in item L are achieved by the present invention as follows. That is, the present invention provides a method for recording a color image by sequentially applying a plurality of color inks each containing a recording agent onto a recording material, in which the Rf value in chromatography of the recording agent contained in the ink used is Indeed, this is a color image recording method characterized by performing recording by applying each color ink in increasing order.

[For production]

The primary colors used in the present invention refer to C1M or Y as a recording means.
Refers to inks or ink compositions that exhibit various colors (sometimes including K (black)), and when the recording agent contained in these recording means is stuck onto a recording material such as paper, the primary colors are Recording is carried out.

When each of the three primary colors C, M, and Y is recorded independently on a recording material, no difference occurs depending on the recording order. However, if another primary color is recorded over a location where one of the primary colors has been recorded, disturbances tend to occur in the recording of the subsequently recorded primary color. In particular, in the inkjet recording method in which recording is performed using multiple primary color inks in extremely short time intervals of 1 millisecond, ink bleeding and disturbances that are thought to be caused by uncertainties in the linear flight properties of ink can occur. Easy to occur.

However, according to the recording order of the present invention, the recording agent recorded first moves less due to the liquid medium of the ink recorded later, and the bleeding between the recording agent recorded earlier and the recording agent after the recording agent is reduced. There is little difference, and there is no color separation or color unevenness within the dots.

Therefore, it is possible to record clearly and with good color reproducibility.

Furthermore, the recording order of primary colors as used in the present invention refers to the recording order of primary colors as in the case of color offset printing, etc.
The method is not limited to the method of recording (printing) in the primary color and then recording in the second primary color.
It also includes the printing order of primary colors for each printing pixel in a system in which printing is performed while scanning a plurality of primary color printing heads on a recording material with extremely short time intervals.

In the recording method of color images, in addition to the method of using the three primary colors of C, M, and Y and superimposing them to create black (GK), there is also a method of recording using K as a fourth primary color in addition to the above three primary colors. There are ways to implement it. In this case, K
The recording order may be determined based on the Rf value in chromatography of the western primary colors including .

Furthermore, the Rf value in chromatography of a recording agent as used in the present invention is expressed as the value of the migration rate Rf (obtained by paper chromatography) defined below.

That is, a test liquid is prepared by dissolving 5% of a desired recording agent in a mixed solvent of water/diethylene glycol (volume ratio: 55/45). After charging the lower end of Toyo Filter Paper No. 50 (trade name; manufactured by Toyo Paper Co., Ltd.) with this test solution for 2 liters, it was developed for a predetermined time using the above mixed solvent as a developing solvent according to a conventional method. At this time, the developing distance (A) of the developing solvent from the charging point and the transfer hole m (B) of the recording material from the charging point are measured, and the value of the ratio of both B/A=Rf is determined. is determined, and this Rf value is taken as the transfer rate of the target recording material.

The recording method of the present invention is not limited to false color recording, but can also be applied to full color image recording using a pixel matrix, dithering method, etc.

Hereinafter, the recording method of the present invention will be explained in detail according to examples.

Example 1 On-demand inkjet recording device that ejects ink using a piezo vibrator (ejection orifice diameter: 304 m)
) was used to reproduce and record a full-color image of 150 x 100 mm using a portrait (a photograph of a female bust) as an original image. In this recording apparatus, four recording heads for each primary color are installed at a spacing of 3ffl, and the recording heads scan the recording material from left to right at a speed of about 1 ts/sec. Therefore, recording the primary colors on the recording material is as follows:
This is done at a minimum interval of approximately 3 milliseconds. The recording conditions are:
In each case, the piezo vibrator driving voltage was 50 V, the pixels were configured in a 3×3 dot configuration, and halftone expression was performed using a combination of the dot matrix method and the dither method.

The recording material is Infusiera I/recording paper (IJ River M:
The product name was Sanfi (manufactured by Paper Manufacturing Co., Ltd.).

Further, as recording liquids for each primary color, inks having the following three compositions were used, and recording was performed in order of decreasing Rf value (cy→M). In this example, printing was performed without ink being supplied to one print head.

Yellow ink C:,! , Acid Yellow 23 3 parts by weight (R
f value 0.90) Diethylene glycol 20//N-methyl-2-pyrrolidone 17 l/water
60tt magenta ink C, 1, acid red 35 3-layered part (Rf
Value 0.95) Diethylene glycol 20//N-methyl-2-pyrrolidone 17 l/water
60tt cyan ink C, 1, Direct Blue 86 3 parts by weight (Rf
Value o, ae) Diethylene glycol 20 l/N-methyl-2-pyrrolidone L7tt water
60//20 panelists (12 men) per color recorded image obtained.
A visual panel test was conducted by 8 female respondents, and the number of people who answered rYe SJ to the following questions was investigated. The results are shown in Table-2.

Question 1: Does the image have the most natural tones (gradation) in the skin color area, with no unevenness in one color? Question 2: Does the image have high resolution and clarity for the eyes and hair? Question 3: Is the overall image superior? Example 2~
4 and Comparative Example 1.2 Recording and evaluation were carried out in the same manner as in Example 1, except that the recording agents shown in Table 1 were used. The results are shown in Table-2.

Table 1 Table 2 [Effects] According to the method of the present invention, a clear color image with good color reproducibility can be obtained without causing color separation or color unevenness within the dots.

Claims (1)

[Claims] In a method of recording a color image by sequentially applying a plurality of color inks each containing a recording agent onto a recording material, the later the Rf value of the recording agent contained in the ink used in chromatography becomes larger. A color image recording method characterized by performing recording by applying each color ink in sequence.