JPH04146461A - Image forming device having image synthesizing function - Google Patents

Abstract

PURPOSE:To minimize an influence on the hue of an image by carrying out the toner image formation of an image region where the number of toner images is less and the hue is hardly influenced, prior to that of the image region where the number of the toner images is many and the hue of the image is easily influenced by the return transfer of toner. CONSTITUTION:In a synthesizing copy, the image regions of two or more are set, image colors are set with respect to respective image regions. Then, image forming order is determined according to respective image colors of inputted image regions. The image forming order according to the image color is previously stored in the memory area of a controller 11 as a table, and the image forming order is determined based on the table. Data for carrying out the image formation in the order that the number of toner colors used is less, is written down on the table. For instance, in the image formed with a color of black (monochrome) and the image formed with three colors of yellow, magenta, and cyan, (full color), the monochrome image is formed prior to the full color image.

Description

DETAILED DESCRIPTION OF THE INVENTION fa) Industrial Application Field This invention relates to an improvement in an image forming apparatus having a function of forming full-color images and composite images.

(b) Prior Art In recent years, some full-color copying machines are equipped with an image composition function. The image compositing function is a function that combines images from different areas onto a single sheet of paper. For example, it is possible to perform compositing such as forming a full color image and a black and white image on a single sheet of paper. can. Formation of such a composite image is performed, for example, as follows.

An image forming apparatus includes a photoreceptor having photoconductivity and a transfer member that comes into contact with the photoreceptor. A toner image can be formed on the photoreceptor by a known electrophotographic method, and the formed toner image is transferred to a transfer member. For example, in the case of combining a full-color image and a monochrome image as described above, yellow-magenta and cyan toner images are sequentially transferred to a transfer body in full-color mode. Then, in black and white mode, a black toner image is transferred to the transfer body, and these four types of toner images are transferred to paper at once.

(C1 Problem to be Solved by the Invention) As mentioned above, when forming a composite image, a method is used in which a plurality of toner images are transferred to a transfer body that is in contact with a photoreceptor, and then transferred to a sheet of paper all at once. However, in this method, the toner of the toner image previously transferred to the transfer member may be transferred back to the photoreceptor, albeit in a small amount, during the next toner image transfer. In the case of a monochromatic image such as black and white, such back transfer is only a problem of density change, but in the case of a full color image, the color tone of the entire image may change.

This phenomenon occurs more easily as the thickness of the toner image layer increases. Therefore, when yellow, magenta, cyan, and black toner images are stacked on the transfer body as in the above example, the first toner image is likely to be back-transferred.
In the case of the above example, the yellow of the full-color image was likely to become pale, and an image with a shifted color tone was likely to be formed.

The present invention places importance on the occurrence of color deviations in full-color images, and provides an image forming apparatus having an image compositing function that can form a composite image while minimizing color deviations in full-color images. The purpose is to

(Means for Solving Problem d1) This invention combines a plurality of image areas on a document into one image area.
A compositing mode that forms a composite image on a sheet of paper, a means for setting an image color for each image area, and an image formation system that sequentially forms an image starting from an area with the least amount of toner used for the image color set for each image area. The present invention is characterized by having a means for performing processing;

(e) Effect In the present invention, when a composite image is formed, the image is formed in order from the area in which the least one type of toner is used. For example, by combining the first region and the second region,
When forming a composite image on a sheet of paper, image colors are set for each of the first area and the second area. For example, the first area is in full color, the second area is in black and white,
The image color is set as follows. The number of toners used for each of these image colors is determined.

For example, in the case of full color, there are three colors, and in the case of black and white, there is one color. Furthermore, in the case of red, there are two colors (yellow and magenta). Then, image forming processing is performed in the order of the number of toners used. That is, images that are likely to be affected by color are formed later.

(f) Embodiment FIG. 4 is a diagram showing a schematic configuration of a full-color copying machine.

A document table 1 made of transparent hard glass is provided on the top surface of the copying machine main body. An original to be copied is placed on the upper surface of the original table 1 with the image side facing down. An optical system 2 is provided below the document table 1 . The optical system 2 includes a light source 2a,
A first mirror heath including mirror 2b, mirrors 2c, 2
d, a second mirror head including lens 2e, color separation filter 2f, mirror=2. g, 2h. The first mirror base and the second mirror base move along the document table 1 as indicated by arrows in the figure, and scan the document placed on the document table 1. The light reflected from the original by this original scanning is reflected by the mirrors 2b to 2d, the lens 2e, the color separation filter 2f,
The light is guided to a photoreceptor, which will be described later, via mirrors 2g and 2h.

The color separation filter 2f has three types of filters for separating the reflected light from the original into the three primary colors of red, green, and blue, and if necessary, one of the filters may be inserted into the optical path of the reflected light from the original. It is inserted and color-separates the reflected light from the original.

A belt-shaped photoreceptor 3 stretched between rollers is disposed below the optical system 2 . The photoreceptor 3 has photoconductivity, and a toner image is formed on its surface by a process substantially similar to that of an electrophotographic copying machine that is widely used in -r. That is, the surface of the photoreceptor 1 is uniformly charged by a charger 31 disposed opposite to its peripheral surface, and then exposed to light reflected from the original by the optical system 2. Then, the charge on the portion of the surface of the photoreceptor 3 that is hit by the light is canceled and an electrostatic latent image is formed. Furthermore, the blank lamp 32 cancels out excess charges on the periphery and the like. In this state, toner is electrostatically attached to the charges remaining on the photoreceptor 3 by the developing device 33. This is the toner image.

Incidentally, in this copying machine, the developing device 33 includes four developing devices. A developing device 33a that stores yellow toner and a developing device 33b that stores magenta toner, respectively.
, a developing device 33C that stores cyan toner, and a developing device 33d that stores black toner. Each developer operates only when necessary; for example, when forming a yellow toner image, the developer 33'a operates, but the other developers 33a to 33c do not operate.

A transfer member 4 is mounted on the side of the photoreceptor 3 so as to come into contact with the photoreceptor 3. The transfer member 4 is made of a dielectric sheet, and is shaped like a belt and stretched between rollers. The dielectric sheet is pressed against the photoreceptor 3, thereby causing the photoreceptor 3 to
The toner image formed on the transfer body (dielectric sheet)
4. Transfer onto the top. A transfer roller 41 is located below the transfer body 4.
is provided so that it can move up and down. The transfer roller 41 moves to a position where it contacts the transfer body 4 (solid line W in the figure) when transferring the toner image on the transfer body 4 to paper, and at other times moves to a position W where it does not contact the transfer body 4 (position W in the figure). (center double-dashed line position).

Paper cassettes 51 and 52 are removably provided on the right side of the copying machine main body. Paper cassettes 51 and 52 store paper of different paper sizes and paper types, and paper is fed from one of the cassettes as needed. A toner image is transferred onto the fed paper at the position of the transfer roller 41. Then, the paper onto which the toner image has been transferred is conveyed by the suction heald 53 to the fixing device 6, where the toner image is fixed, and then discharged from the main body of the copying machine.

Here, the image forming process will be briefly explained.

For example, copying a full-color image is performed as follows.

First, blue reflected light from the original is extracted by the color separation filter 2f, and a latent image is formed on the photoreceptor 3 with the blue light. Toner of a color complementary to the color of the light is attached to this latent image. That is, yellow toner is attached to the latent image formed with blue light to form a yellow toner image.

This toner image is once transferred to the transfer body 4, but at this time, the transfer roller 41 is not in contact with the transfer body, so that the toner is not transferred to the paper. Subsequently, a magenta toner image is formed on the photoreceptor 3. The operation is almost the same as that described above, but in this case, the color separation filter 2f
A latent image is formed by transmitting only green light, and magenta toner is attached to the formed latent image by the developing device 33b. The magenta toner image thus formed on the photoreceptor 3 is transferred to overlap the yellow toner image already transferred onto the transfer member 4. Further, in a similar process, a latent image is formed on the photoreceptor 3 by the extracted red document reflection light, and a cyan toner image is formed. This toner image is also transferred to the transfer member 4 so as to be superimposed on the yellow and magenta toner images, and the three-color toner images of yellow, magenta and cyan form one image on the transfer member. These three-color toner images are transferred onto the paper at once, forming a full-color toner image on the paper.

In this way, when combining several toner images to form one image, the photoreceptor 3. The images formed above are combined on the transfer body 4. This also applies when forming a composite image. For example, when a full-color image and a black-and-white image are combined and copied onto a single sheet of paper, the full-color image and the black-and-white image are once combined on the transfer medium. It is then transferred to paper. Composite copying of a full-color image and a black-and-white image is explained in terms of the number of toner images. To form a full-color image, three toner images are composited on the transfer member. Then, a black toner image is further superimposed and synthesized on top of these three toner images. This is a combination of a full color image and a black and white image.

FIG. 2 is a block diagram of the main parts of the copying machine.

The entire copying machine is controlled by a controller 11. Copying conditions are input to the controller 11 from an operation panel 12, and detection states are input from various sensors.

The controller 11 controls the main motors 13 . The optical system motor 14, the clutches of each rotary operation section, any one of the developing devices 33a to 33-d, etc. are operated. The operation panel 12 is provided with keys for setting a composite copy mode, keys for selecting a color mode of an image area, and the like.

FIG. 1 is a flowchart showing the processing procedure for composite copying in the copying machine.

First, when the composite copy mode key is pressed, the composite copy mode is set, and it becomes possible to set the image area to be composited and the image color (nl→n2). For example, when setting the image area, the size of the image area is a specified size (B5, A4, etc.)
If so, it may be input with that size,
Also, for example, known coordinate manual means (pressing a coordinate position key,
This may be done by inputting coordinate values, etc.). In the case of composite copying, at least two or more image areas are set, and an image color is set for each image area. FIG. 3 shows an example of the document set state in composite copy mode. For example, two documents 1a and lb are placed side by side on document table 1, document 1a (first image area), document 1b ( Second
The document size of the image area) is input.

Image colors are, for example, black and white, full color, red, etc.
For example, if the original 1a is a black and white image and the original 1b is a full color image, both are black and white.

Full color is entered. If you set the area and image color for each image area and operate the end key, the condition input for that image area will be completed (n3→n4゜n5→n6...)
. After setting the necessary image area and image color in this way, if the print switch is pressed (n7.n8
), composite copy processing is performed. First, the order of image formation is determined according to the image color of each image area that has been input up to that point. The order of image formation according to the image color is stored in advance in the memory area of the controller 11 as a table.
The image formation order is determined based on the table.

Data is written in the table so that image formation is performed in order of the number of toners used. For example, black 1
Images formed by colors (black and white), yellow, magenta,
In the case of an image formed in three colors of cyan (full color), image formation is performed first on a black and white image. For example, in the case of a full-color image (red) and a two-color image (yellow-magenta), the red image is formed first.

Once the image formation order is determined based on the table data in this way, copying processing is performed based on that order (n
9→n1O).

(G1 Effects of the invention As described above, toner image formation in image areas with a large number of toner images that are likely to affect the image hue due to back transfer of toner is postponed, and toner image formation in image areas with a large number of toner images that are likely to affect the image hue due to back transfer of toner is postponed, By forming a toner image in the image area first, the effect on the image tone can be minimized and a significant deterioration in the quality of the formed image can be prevented.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing the processing procedure for composite copying of a copying machine according to an embodiment of the present invention, Figure 2 is a block diagram of the main parts of the same copying machine, and Figure 3 is an example of setting originals for composite copying. FIG. 4 is a diagram showing a schematic configuration of the copying machine. 1-Original table, 2-Optical system, 3-Photoconductor, 4-Transfer body, 4
1-Transfer roller.

Claims (1)

[Claims] (1) A composition mode that combines multiple image areas on a document to form a composite image on a single sheet of paper, a means for setting an image color for each image area, and a means for setting an image color for each image area. 1. An image forming apparatus having an image compositing function, comprising: means for performing image forming processing in order from an area with the least number of toners used for an image color.