JPS6224271A - Multi-colored recording method - Google Patents

Abstract

PURPOSE:To attain a method which is free from a color shift and a drop in chroma and is match for offset color printing in terms of visible feelings by permitting the area of a fixed secondary color picture part to account for more than 85% with respect to the area of a secondary color picture part to be repeated. CONSTITUTION:The area of the secondary color picture part where toner is superimposingly recorded is set so as to account for more than 85% with respect to the area of the secondary color picture to be repeated. Namely, when the toner is superimposingly recorded to repeat the secondary color, a lower toner single color part, an upper toner single color part and a secondary color part are mixed, and its area must account for more than 85% with respect to the area of the picture to be repeated. Assuming that a green picture is repeated through use of yellow toner and cyanogen toner, the green part accounts for more than 85% in the picture, and the parts only in yellow and only in cyanogen account for less than 15%. Then the picture satisfying said ratios is formed, and is free from the color shift and the drop in chroma.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a multicolor recording method using electrophotography or electrostatic recording, and in particular - to obtain a secondary color image by overlappingly recording next color toners. Concerning multicolor recording methods.

[Conventional technology]

According to each color image obtained by color-separating the multicolor original image, for example, cyan, magenta, and yellow, images are formed on the recording material using black toner, and the multicolor image is reproduced. A method is proposed.

In such a method, image formation is performed using toners of three primary colors by overlapping recording for each color toner. When reproducing secondary colors relative to the three primary colors, such as green, red, and blue, the secondary colors are obtained by laminating two types of secondary color toners.

For example, when reproducing a green image, color separation exposure is performed using a blue filter to form an electrostatic latent image corresponding to the yellow color component, this electrostatic latent image is developed with yellow toner, and this yellow toner image is transferred. Transfer to paper. Next, the electrostatic latent image obtained by color separation with a red filter is developed with cyan toner to obtain a cyan toner image, and this cyan toner image is superimposed on the aforementioned yellow toner image E to form a secondary image. A green image is obtained by obtaining a color toner image and fixing it. Therefore, it is necessary to take sufficient consideration to positional misalignment when overlapping recording to avoid color misalignment, but even with sufficient alignment, the color reproducibility may be unsatisfactory due to color unevenness, decreased saturation, etc. It is not something that is done. As shown in FIG. 2, the reproduced green image area is made up of one layer of cyan toner and one layer of yellow toner, and the cyan and yellow toners are completely layered.
If there is no single yellow toner, this kind of color unevenness, decrease in saturation, etc. will not occur, but in reality, the third toner
As shown in the figure, the layered state is not complete, but there are parts where cyan and yellow toner layers are stacked, a single cyan toner part, and a single yellow toner part, and this state causes color unevenness and saturation. A phenomenon such as a decrease occurs.

〔the purpose〕

In view of the above points, the present invention provides a multicolor recording method that achieves good color reproduction without color unevenness or decrease in saturation in multicolor image reproduction.

[Structure] The present invention provides a multi-color recording method in which toner is overlaidly recorded, in which the area of the secondary color image portion where the toner is overlaidly recorded occupies 8b or more of the area of the secondary color image to be reproduced. This is a multicolor recording method that uses several methods.

In other words, when reproducing secondary colors by overlapping toner recording,
As mentioned above, the lower single-color toner part, the upper single-color toner part, and the secondary color part exist in a mixed manner, and the area of this secondary color part is made to occupy 85% or more of the area of the image to be reproduced. This is a multicolor recording method.

The details of the present invention will be explained below with reference to the drawings.

The first factor shows an example of an apparatus to which the multicolor recording method of the present invention is applied, and a document 2 having a multicolor original image is placed on a platen 1. The photoreceptor 3 is uniformly charged by a corotron 4 and then irradiated with a one-color separated image. The exposure lamp 5E irradiates the document, and the light that passes through the color separation filter 6 irradiates the surface of the photoreceptor.

Color separation filters are blue (6@), red (6b), green (
The three filters 6c) are switchably provided, and the light passing through these filters forms an electrostatic latent image corresponding to the primary color component on the photoreceptor. The figure shows a case where an electrostatic latent image corresponding to a yellow color component is formed. The photoreceptor having an electrostatic latent image corresponding to a single color then forms a toner image by a developing means 7. This developing means 7 includes a yellow developing means 72, a cyan developing means 7b, a magenta developing means 7c and a black developing means 7d. , and is configured so that only the developing means of the color corresponding to the latent image to be developed is operated.For the yellow latent image, the yellow developing means 7 is operated.
a is activated to form a yellow toner image on the photoreceptor.

8 is a transfer drum, and this transfer drum 8f is wrapped with transfer paper 9 and transfers the yellow toner image to the corotron 1.
0 onto the transfer paper. The transfer paper 9 is held on the transfer drum 8 until the next step of transfer is performed.

On the other hand, the photoreceptor 3 after the transfer is cleaned of residual toner and neutralized, and then a latent image is formed by second color separation exposure.

A latent image corresponding to the cyan color component is formed from the light I that has passed through the red filter 6b, and a cyan toner image is obtained by the cyan developing means 7b, which is superimposed and transferred onto the transfer paper 9 on which the yellow toner image has been formed. One layer of yellow toner and one layer of cyan toner are laminated on the transfer paper 9 from the transfer paper side, forming a toner image of green, which is a secondary color. This transfer paper 9 is separated from the transfer drum 8 and is fixed by a heat fixing means 11 to form a color image.

The color image on the transfer paper is configured such that the secondary color portion occupies 85% or more of the area of the image to be reproduced.

In the apparatus shown in FIG. 1, a fine powder having an average particle size of 7 μm or less is used as the toner, and a contact heating means consisting of a heating roll and a pressure roll is used as the fixing means. By using fine powder toner, the gaps between toner particles in an unfixed toner image become smaller, making it possible to form an unfixed toner image that almost completely fills the substrate, transfer paper, or toner layer to be fixed. The slight gaps between the toner particles are filled by applying heat and pressure at the same time using a contact heating means, so that the toner flows.
This causes the toner particles to come into contact with each other and fill the gaps.

For example, when a green image is reproduced using yellow toner and cyan toner, an image is formed in which the green color portion in one image is 8b or more, and the yellow or cyan color only portion is 15% or less, The resulting image will have no color shift and no decrease in saturation.

As mentioned above, the fixed multicolor toner image has a cross section as shown in FIG. A cyan color portion and a yellow color portion exist, and these monochromatic cyan color portions and yellow color portions cause color shift and decrease in saturation. In order to examine the relationship between the area ratio of each toner and the color reproduction range, the results were obtained when the area ratio of each toner was 100'fi and 96%. The area ratio indicates the area ratio of the toner adhered part to the area to be reproduced, and as is clear from Figure 4, when the area ratio is 96%, the color reproduction range decreases, especially the color reproducibility of green color. are doing.

In other words, when the area ratio of the toner on the transfer paper decreases, the color reproducibility decreases, and in particular, the color reproducibility of a green image, which is a secondary color, decreases. The reason why the X6 reproducibility is particularly low is the color saturation tear and green images with Claw 7 (Ch.
rome.

When the relationship between the saturation (in the Munsell color chart system) and the area ratio of the toner image was investigated, the results shown in FIG. 5 were obtained.

The fJs diagram shows the relationship between Claw 7 and the surface IR ratio of the non-reproducible color portion. There was a nearly linear relationship with the area ratio of the reproduced color portion. Furthermore, if Claw 7 is approximately 12 or more, the result will be a multicolor image comparable to offset color printing, and there will be no decrease in visual saturation, and the area ratio of non-reproducible color portions will be 15 or less. I found out that it's good.

Similar results were obtained as shown in Fig. 5 when the same fζ test was performed on toners with various types, amounts, and dispersion states of the colorant used in the toner.
If the area of the image-recorded secondary color image area to the secondary color image area to be reproduced is 85% or less, a multicolor image with excellent color reproducibility can be obtained.

The secondary color image area to be reproduced is the secondary color image area, which refers to the area where each single color toner is attached either singly or overlappingly. ◎ Figure 6 shows the apparatus shown in Figure 1. The color reproduction gamut was investigated for a multicolor image in which the area of the recorded secondary color image area was 86% using the method of the present invention. For reference, images formed by offset color printing are shown. As is clear from FIG. 6, offset color printing produced nearly comparable multicolor images.

To obtain a multicolor image with such an area ratio.

As described above (method of reducing the toner particle size or applying pressure so that the toner particles come into molten contact with the fixing device).

There is a method of controlling temperature or contact time, and a method of controlling the amount of toner adhering to a recording material such as transfer paper may also be used. The amount of toner adhesion can be controlled by selecting development conditions or transfer conditions so that particles of each single color toner can come into contact with the recording material.

The development conditions are the development speed, the amount of toner supplied, or the development bias, and the transfer conditions are the transfer electric field. In order to prevent the area ratio from decreasing due to the agglomerated toner,
An anti-agglomeration agent such as silica may be added to the toner, or the surface energy of the toner may be made low.

A sheet of paper, plastic, etc. is used as the recording material.

It is preferable to use a sheet whose surface has been smoothed. This is because when a sheet with a highly smooth surface is used, the toner image tends to flow in the direction of the sheet surface during fixation (and the area ratio can be made higher). 400 seconds or more, or the surface roughness is maximum (maximum amplitude 5 μm or less, frequency is 12 cycles/■ or less, and includes paper that has been coated or calendered.

EXAMPLE A multicolor image was formed on coated paper using the apparatus shown in FIG. 1 using toners of three colors, yellow, magenta, and cyan, containing 3 parts by weight of TCPA material in a polyester resin and having an average particle size of 7 μm. The developed toner weights at this time were 0.7, 0.8, 06119/-, respectively. In addition, heat roll fixing was used as a fixing means, and a heating roll coated with a 49-diameter aluminum core coated with silicon RTV%Q and a 3-inch thickness and a silicon HTV coated on a 491-diameter aluminum core was used.
Applied load 51 with a pressure roll coated with a thickness of 8-
Fixing was carried out at 15i and speed of 507mm. The area ratio of the secondary color portion l of the fixed multicolor image was as follows.

The color reproduction range of this multicolor image was also investigated. 7th result
Figure 1 is shown. The broken line B' in the figure shows the result of the multicolor image produced by the method of the example, and for reference, the case of offset color printing is shown by the solid line A.As is clear from these, especially the secondary color part The area is 85
It has been found that by setting the color ratio to 100% or higher, it is possible to obtain a multicolor image with excellent color reproducibility without color shift or decrease in saturation.

〔effect〕

As detailed above, 1. When forming a multicolor image by overlapping toner images, the area of the fixed secondary color image portion is 85 inches or more relative to the area of the secondary color image portion to be reproduced. By configuring it in this way, it is possible to form a multicolor image with excellent color reproducibility comparable to offset color printing without color shift or decrease in saturation. .

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an apparatus to which the multicolor recording method of the present invention is applied, FIGS. 2 and 3 are sectional views illustrating a fixed image, and FIG. 4 is a sectional view illustrating a color gamut. Figure 5 shows the relationship between non-reproduced color area ratio and chroma, Figures 6 and 7
The figure is a diagram showing the color reproduction range of a multicolor image obtained by the present invention. Engraving of drawings (no changes in content) Figure 1, Figure 2, Figure 3, - Figure 4 □ Input Figure 5, Figure 6, Figure 7

Claims (1)

[Claims] 1) In a multicolor recording method in which a secondary color image is formed by overlappingly recording multiple colors of toner on a recording material, the area of the fixed secondary color image portion should be reproduced. A multicolor recording method characterized in that the secondary colors occupy at least 85% or more of the area of the image. 2) The multicolor recording method according to claim 1, wherein particles having an average particle diameter of 7 μm or less are used as the toner.