JPH065406B2 - Multicolor image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus that forms a multicolor image by using an electrophotographic method, and in particular, it includes a toner replenishing device that replenishes toners of different colors. And an image forming apparatus having a plurality of developing devices.

[Prior art]

2. Description of the Related Art Conventional multicolor image forming apparatuses include one in which toner images of respective colors formed on an image forming body are sequentially transferred onto recording paper, and the toner images of respective colors are superposed on the recording paper. However, in such a multicolor image forming apparatus, there is a problem that the apparatus becomes large because a transfer drum is required, or a clear multicolor image cannot be obtained due to transfer deviation of toner images of respective colors. So, for example, Japanese Patent Application No. 58-183152 and Japanese Patent Application No. 58-18
4381, Japanese Patent Application No. 58-187000, and Japanese Patent Application No. 58-187001 propose a multicolor image forming apparatus in which toner images of respective colors are superposed on an image forming body. FIG. 3 and FIG. 4 are diagrams illustrating the configuration of the image forming apparatus. In FIG. 3, reference numeral 1 denotes a drum-shaped image forming body, a conductive substrate, a selenium vapor deposition layer provided thereon, a resin dispersion layer of cadmium sulfide or zinc oxide, polyvinylcarbazole, anthracene, a polycyclic quinone dye or a bisazo dye. And a photosensitive layer composed of an organic semiconductor. The image forming body 1 is rotated in the direction of the arrow to be positively and uniformly charged by the charger 2, and thereafter, an image is exposed through the laser device 3 by a kind of image information from the original document to be electrostatically charged. An image is formed. This electrostatic image is developed by the developing device 4A to form a corresponding toner image. The image forming body 1 carrying the toner image passes through the developing devices 4B to 4D, the pre-transfer charging device 5, the pre-transfer exposure lamp 6, the transfer device 7, the pre-cleaning static eliminator 9, and the cleaning device 10 without passing through them. Then, the charger 2 is rotated again.

After being uniformly charged by the charger 2, image exposure based on another type of image information is performed to form an electrostatic charge image,
A corresponding toner image developed by the developing device 4B is formed so as to be superposed on the toner image.

The same process is repeated, and the developing device 4C and the developing device 4D develop the respective toner images to form a multicolor toner image in which the toner images are superposed.

This multicolor toner image is easily transferred by the operation of the pre-transfer charger 5 and the pre-transfer exposure lamp 6 which are stopped, and then transferred to the recording paper P by the operation of the transfer device 7, and further by the fixing device 8. It is fixed by applying pressure or pressure. After the transfer is completed, the image forming body 1 is destaticized by the destaticizer 9 including the destaticizing lamp 9a and the corona discharger 9b, and the residual toner is cleaned by the cleaning blade 11 of the cleaning device 10 which was released during the toner image formation. Prepared for the next image formation.
It is preferable that the developing devices 4A to 4D mounted on the multicolor image forming apparatus are developing devices using the non-contact developing method shown in FIG. It is desired to provide a developing device using a non-contact developing method because it does not damage the image and it is extremely easy to turn on / off the development. When the development is off, the AC bias component at the time of development (on) is cut off to leave only the DC bias component, the floating state, the grounding, or the DC bias of the opposite polarity to the toner is applied. Alternatively, the developing device is separated from the image forming body. Also, these treatments can be used in combination.

In the developing device of FIG. 4, reference numeral 21 denotes a developer carrying member, which is composed of a sleeve 21a and a magnet body 21b. A developer agitator 22 in the developer reservoir 23 agitates and mixes the toner replenished from the toner replenishing hopper 25 by the replenishing roller 24 and the developer scraped from the surface of the sleeve 21a by the doctor 27. Reference numeral 29 is a protective resistance, and 28 is a DC and AC bias power supply to the sleeve 21a. When AC bias is actuated, toner flies from the agent layer on the surface of the sleeve 21a toward the image forming body 1 and develops without contact. Is carried out.

[Problems to be solved by the invention]

When the multicolor image formation described above is performed, a part of the toner image on the image forming body is mixed in the developing device, and as a result, the developed image becomes turbid and the color balance is disturbed.

That is, after transfer and cleaning, a small amount of toner remaining on the image forming body is mixed and accumulated in each color developing device in the process of repeatedly forming an image many times. Further, particularly in the second and subsequent developing devices for forming a multicolor image, a part of the toner image formed on the image forming body by the previous development returns to the developing device due to the action of the AC bias and the DC bias. As a result, the adverse effect of the color turbidity of the image is remarkable. Therefore, conventionally, the developing device in which color mixing has occurred is taken out and the developing device or the developer is replaced. However, this work is complicated because the positional accuracy for mounting the developing device to the main body of the apparatus is required, and therefore the work of a specialized service person is often troublesome. Therefore, an apparatus that automatically replaces the developer may be considered, but there is a problem that the apparatus becomes complicated and large.

[Means for solving problems]

The present invention is proposed in view of the above-mentioned circumstances, and does not cause a problem in practical use due to an extremely simple improvement of the color mixing of different-color toners in the developing device without complicating the device or increasing the size thereof. An object of the present invention is to provide an image forming apparatus that can be reduced.

The above-mentioned object has a plurality of developing means for receiving replenishment of toners of different colors from the toner replenishing device, and forms a multicolor image by superposing toner images of different colors on the image forming body by the plurality of developing means. In the multicolor image forming apparatus
Toner that consumes toner in the developing device by forming a solid latent image outside the image forming area facing the developing device prior to the image forming area of the image forming body and developing the solid latent image to a predetermined density. The present invention is achieved by a multicolor image forming apparatus having a consuming unit, wherein the plurality of developing units develop the latent image in the image forming area after developing the toner consuming unit.

[Action]

FIG. 1 is a plan view for explaining the operation of the present invention, in which 1 is an image forming body, but a drum-like image forming body mounted on the multicolor image forming apparatus of FIG. As shown. In FIG. 1, the image forming area B of the image forming body 1
A solid latent image for the purpose of consuming the mixed color toner is formed in the area A other than the area A.

That is, at the first time of the image forming body 1, the charger 2 of FIG.
A uniform charge is imparted to all areas A and B by means of image exposure from the laser beam scanner 3 which is modulated by a kind of color signal from the information source.
A solid latent image Y ₁ is formed in the area B, and an image latent image Y ₂ is formed in the area B. Here, the solid latent image Y ₁ is for consuming the mixed color toner in the developing device _first by the developing process and for reducing the adverse effect of the mixed color toner at the time of developing the subsequent image latent image Y ₂ . Next, the latent image is developed with the toner corresponding to the one type of color signal in the developing device 4A, but the development of the preceding solid latent image consumes a considerable amount of the mixed toner in the developing device 4A.

Therefore, the image latent image Y ₂ is developed with the preferable toner which contains the toner replenished from the toner replenishing device and in which a considerable amount of the mixed color toner is removed.

After the image forming body 1 has been rotated twice, the developing devices 4B, 4C and 4D are similarly processed.
Thus, a multi-color toner image in which toner images are sequentially developed to form the toner images in a superimposed manner and adverse effects of mixed color toners are reduced can be obtained.
At this time, the developing operation is turned on after passing through the previously developed solid portion.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3, but the embodiment of the present invention is not limited thereto.

〔Example〕

FIG. 2 shows the operation timing of each image forming apparatus when the present invention is carried out by using the multicolor image forming apparatus of FIG. The image forming body 1 to be incorporated in the apparatus is formed by providing a selenium and arsenic vapor deposition layer on the surface of an aluminum drum, and has a diameter of 120 mm. The image forming body 1 is rotated in the direction of the arrow at a speed of slightly more than 3 seconds per rotation, and four rotations form four toner images of yellow, magenta, cyan, and black in a superimposed manner. First, in the first one rotation, the corona charger 2 applies a uniform charge V _y of +600 V to the image forming body 1, and the semiconductor laser beam scanner 3 writes yellow information on the charge V _y , and the yellow solid latent image E _y1 and A yellow image latent image E _y2 is formed. These latent images are reverse-developed with the positive yellow toner by the developing device 4A and the yellow solid toner image D is developed.
_y1 and a yellow image toner image D _y2 are formed.

After the second rotation of the image forming body 1, the solid latent image forming position is the first position.
Figure and different outer sequential uniform positive charge V _M in the same manner as shown in FIG. 2, V _C, V _B is applied, a solid latent image E _M1 by writing laser beam, E _C1, E _B1 And image latent images E _M2 , E _C2 , E E _B2 are formed. These latent images are successively developed by the developing devices 4B, 4C, 4D to form a superposed multicolor toner image. At this time, since the solid latent image is developed prior to the development of the image latent image in each developing device, a considerable amount of the different color toner mixed in the toner flowing in the developing device is consumed. For this reason, when a subsequent image latent image is developed, a large amount of replenishment toner is contained, and the adverse effect of mixed color toner is reduced.

The writing and development of the solid latent image may be appropriately stopped when the color mixture in the developing device is small, or a writing or developing interval may be provided. The writing position of the solid latent image may be after the image latent image.

Further, the development density of the solid latent image may be appropriately changed to control the toner consumption amount. It may also be used to control the toner density from the development density of a solid latent image, and to feed back the charging potential and the development bias. In the above-described embodiment, the multicolor toner image is formed by rotating the image forming body 1 a plurality of times, but it may be formed by rotating the image forming body 1 once.

〔The invention's effect〕

As described above, in the image forming apparatus of the present invention,
When color mixture occurs in the toner in the developing device, it is possible to reduce the adverse effect of color mixing to a practically unimpeded degree by a very simple means without taking out the developing device. Further, since a complicated device is not required, there is an advantage that an increase in size of the device and an increase in cost can be avoided.

[Brief description of drawings]

FIG. 1 is a plan view of an image forming body for explaining the operation of the present invention, FIG. 2 is a diagram showing the operation timing of each image forming device of the multicolor image forming apparatus, and FIG. 3 is a multicolor image forming apparatus. Cross section of
FIG. 4 is a sectional view of a developing device mounted in the multicolor image forming apparatus of FIG. 1 ... Image forming body 2 ... Charging device 3 ... Laser beam scanner 4A, 4B, 4C, 4D ... Developing device 5 ... Pre-transfer charging device 6 ... Pre-transfer exposure lamp 7 ... Transfer device 9 ... Pre-cleaning static eliminator 10 ... Cleaning device P ... Recording paper 21 ... Developer transport member 25 ... Toner supply hopper 24 ... Toner supply roller 28 ... Bias power supply

Claims (1)

[Claims] 1. A multi-color image having a plurality of developing means for receiving toners of different colors from a toner replenishing device and superposing toner images of different colors on an image forming body by the plurality of developing means. In a multicolor image forming apparatus for forming, a solid latent image outside the image forming area facing the developing device is formed in advance of the image forming area of the image forming body, and the solid latent image is developed to a predetermined density to develop. A multicolor image forming apparatus comprising: a toner consuming unit for consuming toner in a container, wherein the plurality of developing units develop the latent image in the image forming area after developing the toner consuming unit.