JPS6172580A - Recording method - Google Patents

Abstract

PURPOSE:To obtain high-quality clear-cut pictures with desired density by an ink jet method by forming color pictures by using a greater amount of black ink than the other color inks. CONSTITUTION:Inks of three or more colors of C, M, and Y including black ink, are printed by adhering greater amounts of black ink picture element to a printing medium, that is, 1.1-3.0 times greater than C-ink, 1.1-3.0 times greater than M-ink, and 1.1-3.0 times greater than Y-ink in the density of pictures, by raising the drive voltage of piezo-electric element to spew forth black ink, raising voltage to be applied to a heating element to heat black ink, or lowering the viscosity of black ink. An aimed color picture can thus be recorded on a light transmissive plastic film or light-impervious recording material.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method of recording a color image on a recording material by using a plurality of colored inks and combining these colored inks by an inkjet recording method. In particular, the present invention relates to a recording method using an inkjet system that can obtain clear, high-quality images with sufficient image density.

(Prior art) Inkjet recording methods include an electrostatic suction method using high voltage application, a method that applies mechanical vibration or displacement to the ink using a piezoelectric element, a method that heats the ink to foam it, and uses the resulting pressure, etc. Recording is performed by generating ink droplets using various ink ejection methods, and making them fly and adhere to a recording material such as paper, which generates less noise.
This is a recording method that allows high-speed printing and multicolor printing. Prints recorded using this inkjet recording method can be used for surface image observation when a non-transparent recording material such as paper or so-called inkjet recording paper is used as the recording material. When a translucent recording material is used as a recording material, it can be used to project a recorded image onto a screen for observation using an optical device such as a slide or OHP (overhead projector), or a color printing positive. It is used for a variety of purposes, including color separation plates when creating plates, and CMF (color mosaic filters) used in color displays such as liquid crystals.

On the other hand, when forming a color image using such an inkgenie two-shot recording method, a typical method is a recording method using a subtractive color mixing method.

When a color image is formed by subtractive color mixing, cyan (C), magenta (M) and yellow (Y) are generally used.
) are used. The following four colors can basically be expressed by mixing these three primary colors in the same pixel, that is, by depositing ink droplets of different colors on the same pixel and recording them.

1) C+M4B (Blue) 2) C+Y-G (Green) 3) M+Y, R (Red) 4) C+M+Y→BK (Black) Like this,
The colors represented by the three primary colors C, M and Y are basically the seven colors C, M, Y, R, G, B and BK,
This multicolor image composed of seven colors is called a false color image.

Therefore, when performing false color recording using such a recording method, it is basically sufficient to prepare three inks for the three primary colors, C1M and Y.

However, when recording is generally performed, in addition to the high frequency of recording with BK, there are also three types of C1M and Y.
When BK is painted with two primary color inks, C,
BK is printed by overlapping ink droplets of the three colors M and Y, and since the same ink droplet volume is used for each color, the three ink droplets overlap and adhere to the recording material.
The dots formed as a result will be enlarged more than necessary compared to areas recorded in colors other than BK, resulting in thicker lines, resulting in an unnatural image, and the amount of ink in those areas may be reduced. Since there is a problem that the ink absorption by the recording material is poor due to the large amount of ink, BK ink is generally used in addition to the three primary color inks of C, M, and Y.

(The problem that the invention is trying to solve) However, C.
When recording is performed using the three primary color inks of M and Y and the four color inks of BK ink, as mentioned above, two ink droplets of different colors are overprinted in the printed areas of B, G and R. On the other hand, only one droplet of BK ink adheres to the BK print area. Therefore, when visually observing an image, the image density of the BK printed area is higher than that of the B, G, and R printed areas, resulting in a natural-looking and clear image. , B, G, and R printed areas, and when lines such as characters and symbols are recorded in BK, they will be observed as thin lines, resulting in blurred or blurred images. This was a factor that gave it a natural look. Among these, printing using a transparent recording material that utilizes the transmitted light of the recorded image ・For objects, it is extremely important to obtain a well-balanced and sufficient image density throughout each part of the image, so the above There was a particular need to solve such problems.

One method for increasing the image density of a recorded image is to increase the density of ink dots recorded using ink with a high recording agent concentration.

However, ink with a high recording agent concentration has problems such as poor storage stability, and in order to obtain good ink characteristics, the ink must be specially adjusted, and it is necessary to increase the recording agent concentration of the ink. However, when recording lines, for example, it was not possible to increase the size of the dots to give the lines sufficient thickness.

On the other hand, image density can be increased by recording ink dots so as to occupy as wide an area as possible, or by recording two ink dots so that at least a portion of them overlaps each other.
It takes extra time to perform recording twice with BK ink, which reduces the recording speed and makes it difficult to apply to high-speed recording. Although it is possible to perform recording without reducing the speed, the recording device becomes complicated and the cost of the recording device increases.

Therefore, an object of the present invention is to use a specially adjusted ink with a high recording agent concentration or to use a new recording head for BK in an inkjet recording method that performs recording using inks of three or more colors including BK ink. without setting up
In particular, it is possible to obtain a black pixel area (BK recording area) of a recorded image with sufficiently high image density while maintaining harmony with other areas and without disturbing the color tone as BK. To provide a recording method capable of recording a black line that can give a sufficiently thick impression even when printing a black line.

(Disclosure of the Invention) The above objects can be achieved by the following present invention.

That is, the present invention provides a recording method in which a color image is formed on a recording material using ink on a two-color area including black, which is characterized by depositing more black ink than other colored inks. It is.

1 To explain the present invention in detail, in the method of the present invention, among the predetermined portions (pixels) on the recording material to which ink is attached and ink dots are formed, the pixel where a primary color other than black is recorded is The object of the present invention is achieved by depositing more black ink on pixels to which black ink is deposited.

A pixel in the present invention refers to the minimum area shared by one color when an image is recorded, and a recorded image is formed by a collection of pixels.

Generally, in order to provide sufficient image density to an image recorded by an inkjet recording method, it is necessary to obtain sufficient pixel density. Basically, pixel density can be increased by making the immersion level of the recorded ink dots sufficiently high, and also by recording ink dots so as to occupy as wide an area as possible within the pixel. can be made higher.

In consideration of these requirements and in order to give sufficient thickness to the line portion, in the method of the present invention, dots of BK ink are recorded within the pixels when recording by the inkjet recording method. , as described above, dots of K ink that are larger than dots of colors other than BK are recorded. ``These BK ink dots must occupy as wide a portion of the pixel as possible in order to obtain higher image density without impairing the resolution of the recorded image and to give sufficient thickness to the line portion. It is preferable to record it so that the

The image recorded by the recording method of the present invention in such a state of ink dots satisfies the above-mentioned requirements for obtaining sufficient density of the image, and the black line portion has sufficient thickness. It is a clear image with sufficient pixel density as a whole.

That is, by recording BK pixels by attaching K ink dots that are larger than those of other primary colors to BK pixels, the area occupied by those ink dots within the pixel becomes wider, and more recording agent components are used. The amount of light absorbed is large depending on the amount of the attached recording agent component, and as a result, the pixel density becomes sufficiently high. Moreover, sufficient thickness can be given to the line portion.

In the method of the present invention, the method for adhering the ink to the recording material is the above-mentioned inkjet recording method, and more specifically, the electrostatic suction method by applying a high voltage, and the method for applying mechanical vibration or displacement to the ink using a piezoelectric element. Various ink ejection methods are used, such as a method in which the ink is heated and foamed, and the resulting pressure is used to eject the ink as small droplets, which are then attached to a transparent or non-transparent recording material to form ink dots. It is something that is made to form.

As the ink used in the recording method of the present invention, all inks that can be used for inkjet recording can be used.

Furthermore, various recording materials that can be used for inkjet recording can be used as the recording material used in the method of the present invention. In particular, if an image is formed by the method of the present invention using a recording material with translucency, such as a recording material made of a translucent plastic film coated with a water-soluble polymer, etc., Clear translucent images with sufficient recording density can be obtained.

In the method of the present invention, the method of depositing BK ink in a larger amount than other primary colors includes a method of increasing the drive voltage of the piezoelectric element or the applied voltage of the heating element that heats the ink when ejecting the ink in the inkjet recording method; This can be achieved by lowering the viscosity of the ink. In particular, in the method of the present invention, the image density of BK ink is about 1.1 to 3.0 times that of other primary color inks, such as C ink, and about 1.1 to 3.0 times that of M ink. It is preferable to attach BK ink to BK pixels so that the image density is approximately 1.1 to 3.0 times that of Y ink. What is necessary is to discharge and deposit the amount in excess by the proportion of .

According to the inkjet recording method of the present invention as described above, when performing color recording using BK ink and non-BK-based ink, the BK recording area is coated with more BK-based ink than non-BK-based ink. By recording, using ink with a specially adjusted high recording agent concentration,
In particular, sufficient recording density is achieved without the need for an extra recording head for BK.

It is possible to obtain a BK printed area with a high level of color, and even when printing lines, it is possible to print lines with a desired thickness.

Furthermore, according to the method of the present invention, even when a color image is recorded using a translucent recording material, when the recorded image is projected with light, a clear projected image with sufficient image density can be obtained. The obtained print can be recorded and can be suitably used for transmission observation.

Hereinafter, the recording method of the present invention will be explained in more detail according to Examples. In addition, parts in the text are based on weight.

Examples 1 to 3 On-demand inkjet recording head that ejects ink using a piezo vibrator (ejection orifice diameter 65p)
Using an inkjet recording device with a driving frequency of 2 kHz), each of the inks having the composition shown below was filled into the inkjet recording device, and a dry film thickness of 10 l was applied to a surface-treated polyester film (manufactured by Kijin Co., Ltd.) with a thickness of 1100 p. Polyvinyl alcohol (trade name) partially saponified to give m.

For the BK recording section, piezoelectric vibrator drive voltages of 1oov (Example 1), 90V (Example 2), and 80V were applied to the transparent recording material coated with KH-17 (manufactured by Nippon Gosei Kagaku Kogyo).
(Example 3), the other primary colors were recorded at 70V, and the test pattern (black, yellow, magenta, cyan) was printed solidly in four 2cs+ squares arranged horizontally on the recording material in this order. (printed) and a pie chart (a pie chart divided by color in the order of yellow, magenta, cyan, red, and green. Within each division, Japan, America, Germany, and the United Kingdom are printed in black in order from the yellow division. , the country name of France is printed, and the title ``1 Pie Chart'' is printed below this pie chart.)
was created.

C, 1, Acid Yellow 23 2 parts diethylene glycol 20 parts polyethylene glycol #200 15 parts water
65 parts Mazen C, 1, Acid Red 92 2 parts diethylene glycol 20 parts polyethylene glycol #200 15 parts water
65 parts 2 2 Otsu" 2 colors - L" Nik C, 1, Direct Blue 86 2 parts diethylene glycol 20 parts polyethylene glycol #200 15 parts water
65 part black”
5: Ni 2 Niku C, 1, Direct Black 19 2 parts diethylene glycol 20 parts polyethylene glycol #200 15 parts water
The recording conditions of the 65 recorded test patterns and pie charts were evaluated for the following items. The results are shown in Table 11.

(1) Image Density of Recorded Image Each solid printed portion of each color of the test pattern was measured using a photographic densitometer (NLM-3TD-Tr, manufactured by Narumi Shokai).

(2) Panel test The pie chart obtained as above was projected onto a screen using 0HP (overhead projector), and 10 panelists judged the visibility of the projected image. . In the panel test evaluation, when the projected image was visually observed, it was found that the entire projected image was clear, the image density of the solid black part itself was sufficient, and even compared to the parts other than the black border. The balance is good, and the coloring of each color is good, especially the character windings such as country names and titles displayed in black are clear and easy to read.If there are people who judged that it is 8 Å or more, if it is 0.17 Å or less, it is marked as ×. did.

Comparative example: The piezoelectric vibrator drive voltage for the black printed area and other primary colors was set to 7.
A test pattern and a pie chart were recorded in the same manner as in Example 1, except that printing was performed at 0 V, and the results were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(ybe lower Yumi Δ) No.-1 Department Y! ! 1

Claims (1)

[Claims] (1) A recording method in which a color image is formed on a recording material using inks of two or more colors including black, which is characterized by depositing more black ink than other colored inks.