JPS6014342B2 - Multicolor image reproduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for reproducing a multicolor image from an original image, and in particular, it is capable of reproducing images with good color balance and faithful color reproduction with a compact configuration. It provides equipment.

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

FIG. 1 is a side view illustrating a specific example of a multicolor image reproduction apparatus based on the present invention.

Each component of the specific example multicolor image reproducing apparatus that is not directly related to the features of the present invention will also be briefly described below for reference in understanding the present invention. The multicolor image reproducing device has a document table 2 made of a transparent glass plate or the like placed on the top surface of a weight body 1, and a lamp 3 illuminates the document with a military calendar on the document table 2, and the document moves with the lamp 3. movable mirror 4 and this mirror 4
With the movable mirror 5 moving at 1/2 of the moving speed of
The original image is scanned.

The scanned original image is exposed onto the photoreceptor drum 10 through an optical system lens 6, a color separation means 7 having a predetermined color separation filter (for example, red 7a, green 7b, and full 7c), and mirrors 8 and 9. be done. The illustrated device uses a photoreceptor having a transparent insulating layer on the surface of the photoconductive layer, and includes a primary charger 11 that applies a corona discharge of a predetermined polarity along the path of movement of the photoreceptor, and a corona discharge of a polarity opposite to that of the primary charger. A secondary charger 12 that performs AC corona charge removal, an exposure lamp 13 that uniformly exposes the surface of the photoreceptor, and a predetermined color developer (
For example, a plurality of developing units 14a, 14b, 14c, 14d supplying cyan, magenta, yellow, and black.
A developing device 14 that holds a transfer material P and has a
A transfer device 15 for multiple-transferring the developer of each color and a cleaning device for removing developer remaining on the surface of the photoreceptor after transfer are disposed thereon. On the other hand, a plurality of cassettes 16, 162, which can be attached to and detached from the crab body 1, make it possible to supply transfer materials P of different sizes. The transfer material P after transfer is conveyed to a fixing section by a conveyor belt 17, further passes through a heating fixing device 18 comprising a plurality of rollers provided in the fixing section, and is sent to a 9E paper tray 19. FIG. 2 is a side view illustrating the developing unit of the developing device of the above-mentioned specific example apparatus.

In the developing unit, a cylindrical sleeve 21 made of a non-magnetic material and rotatably supported is provided in a unit cliff body 20, and within this sleeve 21, a unit lotus body 201 is fixed or movable relative to the sleeve. A magnetic roller 22 is provided. The developer T accumulated in the lower part of the unit sparrow body 20 is held on the sleeve surface by the magnetic field formed by the magnetic roller and forms a developing brush. In order to adjust the height of the developing brush, the doctor blade 23 is fixedly installed on the unit bell body 20 so that its tip is kept at a predetermined distance from the surface of the sleeve 21. The sleeve 21 rotates in the direction of the arrow, and the developer held on the surface of the sleeve is adjusted to a predetermined spike with a doctor blade 23, and then comes into contact with the surface of the photoreceptor 10, and the developer held on the surface of the sleeve is brought into contact with the surface of the photoreceptor 10, and the developer held on the surface of the sleeve is Develop the electric image.

The developer used for development is scraped onto the surface of the sleeve 21 by a scraper blade 24 whose tip is in contact with the surface of the sleeve 21.
1 scraped off from the surface. On the other hand, the magnetic pole of the magnetic roller inside the sleeve is not placed near the scraper blade as shown in the figure L, thereby increasing the scraping efficiency of the scraper blade and preventing re-adhesion. It has gained. At the lower part of the unit land body 20, there are arranged frame blades 25 for receiving the scraped developer, the accumulated developer, and the replenishing developer from a supply means (not shown). In the apparatus according to the embodiment of the present invention, the above-mentioned developing units are provided below the photoreceptor drum as shown in the first diagram. The developing units 14a', 14b and 14c which supply the respective color developers of , cyan, are arranged in the same manner with respect to the direction of movement of the photoreceptor, and therefore, the rotation directions of the developing units and sleeves coincide with each other.
Also, the rotation of the photoreceptor drum is the same, and the sleeve rotates clockwise in the opposite direction relative to the photoreceptor surface.

On the other hand, since the developing unit 14d that supplies black developer is arranged symmetrically with respect to the moving direction of the other units and the photoreceptor, the rotation direction of its sleeve is opposite to that of the other units, and the photoreceptor surface is Rotate counterclockwise to perform forward development.

Although the details of the mechanism of each development phenomenon are not clear, it was found that the characteristics were different between reverse development and forward development, and a tendency as shown in the third figure was found. FIG. 3 shows the electrostatic latent image potential formed based on the original line image in one rib. FIG. 3 shows the developed density when the electrostatic latent image is developed in the forward direction (indicated by a dashed line) and in the reverse direction (indicated by a broken line).

As shown in the figure, there is a tendency for the image density to differ between the leading edge and the trailing edge depending on the direction of development, which has an extremely large effect on multicolor reproduction faithful to the original image.

In other words, even if the latent image potentials between the original color separation images are mutually balanced, when each latent image is developed in the reverse direction and in the forward direction, the leading and trailing ends of the image portion will be different as described above. This is because, since the densities are different, the colors are different in multicolor reproduction, making it difficult to reproduce faithful colors.

In addition, if all the developing units are arranged in the same way, ``In other words, if the developing unit 14d that supplies the black developer shown in the figure is also arranged in the same way as the others, although the developing direction is the same, the developing efficiency will be poor. Become.

In the illustrated device, the defects were significant when the number of days exceeded 1200. Although all the reasons for this are not clear, in the illustrated example device, the strength of the magnetic lines of force from the magnetic poles of the magnetic roller disposed inside the sleeve is insufficient to hold the developer and feed it to the photoreceptor surface. It is expected that On the other hand, when arranged as in the apparatus configuration of the specific example of the present invention, the developer adsorption power of the magnetic loaf is not impaired, so that extremely suitable development is possible. Therefore, especially in a developing unit that does not involve in mixed color development, such as a black developer, it is extremely suitable in practice to arrange the rotation direction of the sleeve in the opposite direction to that of other units at a position where the developing efficiency is improved. FIG. 4 shows a modification of the developing unit, which has a configuration that allows it to be easily placed on the side of the photosensitive drum, that is, close to the horizontal surface including the drum rotation axis.

As shown in the figure, the doctor blade 23', scraper blade 24', hawk blade 25', etc. have been rearranged to suit the horizontal position. In addition, a doctor blade 23' that adjusts the height of the developer blade is attached to a pin 23 on the unit cover.
The blade 23 is rotatably supported within a region defined between the blade 23' and 232'.
' is moved to the broken line position to prevent the developer from adhering to the sleeve 21.

[Brief Description of the Drawings] Fig. 1 is a side view of a specific example of a multicolor image reproducing device based on the present invention, Fig. 2 is a side view of a developing unit of a developing device, and Fig. 3 is a side view of forward development and reverse development. FIG. 4 is a side view of a modified example of the developing unit. In the figure, 1 is the land body of the multicolor image reproduction device, 2 is the document table, 3 is the illumination lamp, 4.5 is the movable mirror, 6 is the optical system lens,
7 is a color separation means, 8 and 9 are mirrors, 10G photosensitive drum, and 141 is a developing device. Figure 1 Figure 4 Figure 2 Figure 3

Claims (1)

[Claims] 1. Electrostatic latent images for each color component are sequentially formed on a drum-shaped electrostatic image carrier, and the formed latent images are developed by a developing means having a color toner corresponding to the color component latent image to form a color image. In a multicolor image reproducing device, a drum-shaped electrostatic image carrier is arranged along the rotational direction, and yellow, magenta, and cyan color toners are applied to the electrostatic image carrier by moving them in the same direction. each developing means, and a developing means that applies black toner to the electrostatic image bearing member that corresponds to the position where the electrostatic image bearing member rotates upward and moves in a direction opposite to the moving direction of the respective color toners; A multicolor image reproduction device comprising: