JPH11282225A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow optimum recycling of toner for a color image forming device, while preventing the deterioration of an image quality from occurring in compliance with the requirement at present for effectively utilizing resources and protecting the environment. SOLUTION: This device is provided respectively with drum type image carrier 11c, 11m, 11y and 11b exclusive for each color of cyan, magenta, yellow and black arranged in a row in parallel with each other, and is allowed to form respective image in monochrome color thereon in an electrophotographic process through repeating processings such as charging, writing, developing, transferring and cleaning, and to form a synthetic color image on a transfer material such as a paper sheet by successively transferring the monochrome image in each color. This color image forming device is provided with a recycling mechanism 10c capable of returning cyan toner recovered by a cleaning means 16, from the image carrier 11c for forming the monochrome image of the first color standing for cyan, for instance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a cyan, magenta, yellow and black colored toner, for example,
The present invention relates to a color image forming apparatus such as a color copying machine, a color facsimile, a color printer, or a multifunction machine for forming a full-color image on a transfer member such as paper. For example, the present invention can be applied to a two-color image forming apparatus using any of red, blue, green and black toner.

[0002]

2. Description of the Related Art Conventionally, color image forming apparatuses of this type are roughly classified into the following two types.

A charging unit, a writing unit, a plurality of developing units for each color, a transfer unit, a cleaning unit, and the like are arranged around one image carrier common to each color, and one developing unit of the plurality of developing units is disposed. Charge, write, develop,
Repeat electrophotographic processes such as transfer and cleaning,
A single color image of a different color is sequentially formed on the one image carrier, the single color image is sequentially transferred for each color to form a composite color image on the same intermediate transfer body, and the color image is transferred. An image is formed on the transfer member.

[0006] Charging means, writing means, developing means, transfer means,
A single color image is formed for each color on a dedicated image carrier by an electrophotographic process in which cleaning means, etc. are arranged and charging, writing, development, transfer, cleaning, etc. are repeated, and each of the single color images is sequentially transferred. To form a composite color image on the transfer member.

In an image forming apparatus of this type, specifically, as shown in FIG.
Image carrier 1c / 1m / 1 for each yellow / black
y · 1b, and an image carrier 1c dedicated to cyan
Around the charging means 2c, writing means 3c (not shown)
A developing unit 4c, a transferring unit 5c, and a cleaning unit 6c are arranged, and a charging unit 2m, a writing unit 3m (not shown), a developing unit 4m, a transferring unit 5m, and a cleaning unit 6m are arranged around an image carrier 1m dedicated to magenta. In addition, a charging unit 2y, a writing unit 3y (not shown), a developing unit 4y, a transfer unit 5y, and a cleaning unit 6y are arranged around the yellow image carrier 1y, and around the black image carrier 1b. Denotes charging means 2b and writing means 3 (not shown)
b / developing means 4b / transfer means 5b / cleaning means 6
b is arranged.

A single-color image is formed for each color on a dedicated image carrier 1c, 1m, 1y, 1b by an electrophotographic process in which charging, writing, development, transfer, and cleaning are repeated, and the single-color image is formed. To cyan, magenta,
The transfer is performed in the order of yellow and black, and a composite color image is formed on a transfer member such as paper conveyed by the conveyance belt 7.

In FIG. 5, symbols Lc, Lm, Ly, Lb denote writing means 3c, 3m, 3 (not shown), respectively.
This is the writing laser light from y · 3b.

[0008]

By the way, today,
Due to demands for effective use of resources and environmental protection, a monochrome image forming apparatus is provided with a recycling mechanism, in which black toner is collected by a cleaning unit, returned to a developing unit, and reused.

However, the color image forming apparatus has not been provided with a recycling mechanism for the following reasons.

In a color image forming apparatus of the type described above, the residual toner remaining on the common image carrier is collected by a common cleaning means for each single-color image transfer, so that the collected toner of each color is mixed. It cannot be returned to the corresponding developing means of each color.

In the color image forming apparatus of the type described above, the colored toner that has been transferred to the transfer member up to that point is reversely transferred to the image carriers 1m, 1y, and 1b for the second and subsequent colors.
The colored toner collected by the cleaning means 6m, 6y, and 6b after the color is mixed with the colored toner previously transferred to the transfer member.

FIG. 4 shows each of the transfer means 5c, 5m, 5y.
5 is a graph showing the relationship between the voltage applied to the transfer member 5b and the reverse transfer amount of toner from the transfer member to the image carriers 1m, 1y, and 1b when the voltage is applied. As can be seen from this graph, even if the applied voltage is changed, the amount of reverse
Can not be.

In view of the above, an object of the present invention is to respond to today's demands for effective use of resources and environmental protection.
In a color image forming apparatus as well, an object of the present invention is to perform optimal recycling of toner without deteriorating image quality.

[0014]

For this reason, the invention according to claim 1 is, for example, according to an embodiment described with reference to FIG. 1 below, for example, cyan, magenta, yellow,
Dedicated image carriers 11c and 11m for each color of black
A single-color image is formed on each of the colors 11y and 11b by an electrophotographic process in which charging, writing, development, transfer, cleaning, etc. are repeated, and the single-color images are sequentially transferred and combined with a transfer member such as paper. In the color image forming apparatus for forming a color image, the colored toner collected by the cleaning unit 16c from the image carrier 11c for forming a single color image of cyan, for example, cyan, is developed by the developing unit 14c.
And a recycling mechanism 10c for returning to the original state.

According to the first aspect of the present invention,
Using the recycling mechanism 10c, the first color toner collected by the cleaning unit 16c is returned to the developing unit 14c from the image carrier 11c that forms the first color monochromatic image, and is reused.

According to a second aspect of the present invention, for example, an image carrier 11c, 11m, 11y dedicated to each color of cyan, magenta, yellow, and black, as in the embodiment described with reference to FIG. Forming a single-color image for each color on the 11b by an electrophotographic process in which charging, writing, development, transfer, cleaning, etc. are repeated,
In a color image forming apparatus for sequentially transferring each single-color image to form a composite color image on a transfer member, a black toner collected by a cleaning unit 16b from an image carrier 11b for forming a black single-color image is developed by a developing unit 14b.
And a recycling mechanism 10b for returning to the original state.

In the invention according to claim 2,
Using the recycling mechanism 10b, the black toner collected by the cleaning unit 16b from the image carrier 11b that forms a black monochromatic image is returned to the developing unit 14b and reused.

According to a third aspect of the present invention, for example, an image carrier 11c, 11m, 11y dedicated to each color of cyan, magenta, yellow, and black, as in the embodiment described with reference to FIG. Forming a single-color image for each color on the 11b by an electrophotographic process in which charging, writing, development, transfer, cleaning, etc. are repeated,
In a color image forming apparatus for sequentially transferring each of the single-color images to form a composite color image on a transfer member, the developing unit applies the colored toner collected by the cleaning unit 16c from the image carrier 11c that forms the first single-color image. 14c, and a recycling mechanism 10b for returning the black toner collected by the cleaning unit 16b from the image carrier 11b for forming a black monochrome image to the developing unit 14b. I do.

According to the third aspect of the present invention,
Using the respective recycling mechanisms 10c and 10b, the first
The first color toner collected by the cleaning unit 16c is returned to the developing unit 14c for reuse from the image carrier 11c that forms a single-color image, and reused while the black toner is formed from the image carrier 11b that forms a black single-color image. The black toner collected by the cleaning unit 16b is
Return to b and reuse.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a main part of a color image forming apparatus according to the first aspect of the present invention.

In the illustrated color image forming apparatus, similarly to the conventional color image forming apparatus shown in FIG. 5, a dedicated drum-shaped image carrier 11c, 11m, 11y, for each color of cyan, magenta, yellow and black is used. 11b are provided in parallel with each other.

A charging unit 12c, a writing unit 13c (not shown), a developing unit 14c, a transfer unit 15c, and a cleaning unit 16c are arranged around the image carrier 11c dedicated to cyan of the first color. Around the image carrier 11m dedicated to the second color magenta, a charging unit 12m, a writing unit 13m (not shown), a developing unit 14m, and a transfer unit 15 are provided.
m. A cleaning unit 16m is arranged.

Around the image carrier 11y dedicated to yellow of the third color, a charging means 12y and a writing means 13 (not shown) are provided.
y, developing means 14y, transfer means 15y, and cleaning means 16y. Around the image carrier 1b dedicated to the fourth color black, a charging unit 12b, a writing unit 13b (not shown), a developing unit 14b, a transfer unit 15b,
The cleaning means 16b is arranged.

In FIG. 1, reference numerals Lc, Lm, Ly, Lb denote writing means 13c, 13m (not shown), respectively.
-Writing laser light from 13y and 13b.

In the color image forming apparatus according to the first aspect of the present invention, the cyan toner collected by the cleaning unit 16c is returned to the developing unit 14c between the first cyan cleaning unit 16c and the developing unit 14c. A recycling mechanism 10c is provided.

Like the recycling mechanism used in the monochrome image forming apparatus, the recycling mechanism 10c is configured by providing a coil member, a spiral member, a screw member, and the like in, for example, a tubular pipe. Then, the rotation causes the cyan toner to pass through the inside of the tubular pipe to the developing means 14 c
Conveyed to.

In the illustrated color image forming apparatus,
This is also similar to the conventional color image forming apparatus shown in FIG.
A transport belt 17 made of PET or the like is stretched between the driving roller 18 and the driven roller 19, and the outer periphery of the transport belt 17 is wrapped around the image carriers 11c, 11m, 11y, 1 as shown in FIG.
1b.

At the time of recording, each image carrier 11 is individually
c, 11m, 11y, and 11b, and rotates the surfaces of the respective image carriers to the corresponding charging means 12c, 12m, and 11c.
12y · 12b, for example, −500 by corona discharge
It is uniformly charged in the range of -700 V.

Next, each writing means 13c-1 (not shown)
Laser light Lc, Lm, Ly, Lb is radiated from an optical element such as a laser diode at 3m, 13y, 13b, and the surface of each image carrier 11c, 11m, 11y, 11b corresponds to color-separated image data. An electrostatic latent image is formed. For example, the writing density at this time is 400 dpi,
The number of gradations is 256 (8 bits).

Subsequently, each developing means 14c, 14m, 14
In steps y and 14b, cyan toner, magenta toner, yellow toner, and black toner are applied, and the electrostatic latent images are visualized to form image carriers 11c, 11m, 11y, and 1 respectively.
1b, a color-separated single-color image is formed.

In the illustrated color image forming apparatus, developers of respective colors are stored in the respective developing means 14c, 14m, 14y, and 14b. As the developer, a two-component developer composed of a toner and a carrier is used.
%, And the toner charge amount is −15 to −25 μC / g.

On the other hand, the image carriers 11c, 11m, 11y
11b, the driving roller 18 is rotated in synchronization with the rotation of the driving roller 11b, and the transport belt 17 is driven to rotate while the driven roller 19 is driven to rotate.
A transfer member such as a sheet is fed downward to each image carrier in time with the monochrome image formed on 1y · 11b.

Then, the transfer means 15c, 15m, 15y
15b, each image carrier 11c, 11m, 11
The single-color image formed for each color formed on y.11b is transferred in the order of cyan, magenta, yellow, and black, and transport belt 1
In step 7, a synthetic full-color image is formed on the transfer member conveyed. In each of the transfer units 15c, 15m, 15y, and 15b,
For example, transfer is performed by corona discharge by applying a voltage of 5.5 kV.

Thereafter, the toner is conveyed by the conveyance belt 17 and sent to fixing means (not shown), where heat and pressure are applied to melt the toner, thereby fixing the transferred image on the transfer member.

After the image transfer, each image carrier 11c-1
The residual toner remaining on 1 m, 11 y, 11 b is scraped off from each image carrier by a polyurethane rubber cleaning blade provided in each of the cleaning means 16 c, 16 m, 16 y, 16 b and collected.

According to the first aspect of the present invention, the recycle mechanism 10c transfers the cyan toner collected by the cleaning unit 16c from the image carrier 11c that forms a single color cyan image to the developing unit 14c. And mixed in the developer of the developing means 14c and reused.

Therefore, according to the first aspect of the present invention, in response to today's demands for effective use of resources and environmental protection, even in a color image forming apparatus, image quality is not reduced by color mixing or the like. The toner can be recycled.

In the example described above, cyan was used as the first color and was transferred to the transfer member in the order of cyan, magenta, yellow and black. However, the invention described in claim 1 is not limited to this order. Magenta may be used as the first color, yellow may be used as the first color, and the determination may be made in consideration of, for example, color reproducibility. do it.

FIG. 2 shows a schematic configuration of a main part of the color image forming apparatus according to the second aspect of the present invention. In FIG. 2, the reference numerals used for the corresponding parts in FIG. 1 are used as they are, and redundant description is omitted.

In the illustrated color image forming apparatus shown in FIG. 2, a recycling mechanism 10b for returning the black toner collected by the cleaning means 16b to the developing means 14b is provided between the fourth color black cleaning means 16b and the developing means 14b. Provided.

The recycle mechanism 10b, like the color image forming apparatus shown in FIG.
It is configured by providing a coil member, a spiral member, a screw member, and the like. Then, by these rotations, the black toner is conveyed to the developing means 14b through the cylindrical pipe.

According to the second aspect of the present invention, the toner recovered by the cleaning means 16b from the image carrier 11b for forming a black single-color image is returned to the developing means 14b by the recycling mechanism 10b. 1
4b mixed into the developer and reused.

By the way, in the toner collected by the cleaning means 16b, each toner of cyan, magenta and yellow reversely transferred from the transfer member to the image carrier 11b is mixed. However, the mixing amount is small, and the chromatic colors of cyan, magenta and yellow hardly affect the hue of achromatic black.

Therefore, according to the second aspect of the present invention, in response to today's demand for effective use of resources and environmental protection,
In the color image forming apparatus, the toner can be recycled and used without deteriorating the image quality due to color mixing or the like.

It should be noted that the invention according to claim 2 is not limited to the transfer in the order of cyan, magenta, yellow and black, and black may be used as the first color or the second color. The third color may be used.
Naturally, the smaller the amount of chromatic color toner to be mixed, the better. Therefore, it is preferable to set black to the upstream side.

FIG. 3 shows a schematic configuration of a main part of a color image forming apparatus according to the third aspect of the present invention. Also in FIG. 3, the reference numerals used for the corresponding parts in FIG. 1 are used as they are, and redundant description is omitted.

In the illustrated color image forming apparatus shown in FIG. 3, between the cleaning means 16c for the first color cyan and the developing means 14c, the recycling mechanism 1 for returning the cyan toner collected by the cleaning means 16c to the developing means 14c.
0c, and a recycling mechanism 10b for returning the black toner collected by the cleaning unit 16b to the developing unit 14b between the fourth-color black cleaning unit 16b and the developing unit 14b.

As in the color image forming apparatuses shown in FIGS. 1 and 2, the recycling mechanisms 10c and 10b are configured by providing a coil member, a spiral member, a screw member, and the like in, for example, a tubular pipe. The rotation causes the colored toner to pass through the cylindrical pipe to the developing means 14c.
14b.

According to the third aspect of the present invention, the toner recovered by the cleaning means 16c from the image carrier 11c for forming a monochromatic image of cyan is returned to the developing means 14c by the recycling mechanism 10c. 14
c, the toner collected by the cleaning unit 16b from the image carrier 11b that forms a black single-color image is returned to the developing unit 14b by the recycling mechanism 10b. 14b
And reused.

Therefore, according to the third aspect of the present invention, in response to today's demand for effective use of resources and environmental protection,
In the color image forming apparatus, the toner can be recycled and used without deteriorating the image quality due to color mixing or the like.

It should be noted that the invention described in claim 3 is not limited to the transfer in the order of cyan, magenta, yellow, and black, but may be an appropriate order in which black is arranged in the second and subsequent colors.

Further, in the examples shown in FIGS. 1 to 3 described above, the case where the present invention is applied to a full-color image forming apparatus has been described. However, the present invention is not limited to a full-color image forming apparatus, but can be similarly applied to a two-color image forming apparatus using any of red, blue, green and a black colored toner. it can.

[0053]

Therefore, according to the first aspect of the present invention, in response to today's demand for effective use of resources and environmental protection,
Also in the color image forming apparatus, the first color toner can be recycled without deteriorating the image quality due to color mixing or the like.

According to the second aspect of the present invention, the hue is not affected even if a chromatic color is mixed to some extent. Therefore, even in the color image forming apparatus, the black toner is not deteriorated due to the color mixture and the like. Can be recycled.

According to the third aspect of the invention, even in the color image forming apparatus, both the first color toner and the black toner can be recycled without deteriorating the image quality due to color mixing or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a color image forming apparatus according to the first embodiment.

FIG. 2 is a schematic configuration diagram of a main part of the color image forming apparatus according to the second embodiment.

FIG. 3 is a schematic configuration diagram of a main part of the color image forming apparatus according to the third embodiment.

FIG. 4 is a graph showing a relationship between a voltage applied to each transfer unit and a reverse transfer amount of toner from a transfer member to an image carrier when the voltage is applied.

FIG. 5 is a schematic configuration diagram of a main part in a conventional color image forming apparatus.

[Explanation of symbols]

 10c / 10b Recycling mechanism 11c / 11m / 11y / 11b Image carrier 12c / 12m / 12y / 12b Charging means 14c / 14m / 14y / 14b Developing means 15c / 15m / 15y / 15b Transfer means 16c / 16m / 16y / 16b Cleaning Means 17 Conveyor belt

Claims (3)

[Claims] 1. A color for forming a single color image for each color individually on an image carrier dedicated to each color by an electrophotographic process, and sequentially transferring the single color images to form a composite color image on a transfer member. A color image forming apparatus, comprising: a recycle mechanism for returning a colored toner collected by a cleaning unit from an image carrier for forming a first color monochromatic image to a developing unit. 2. A color forming a single-color image for each color by an electrophotographic process on a dedicated image carrier for each color, and transferring the single-color images in order to form a composite color image on a transfer member. A color image forming apparatus, comprising: a recycle mechanism for returning a black toner collected by a cleaning unit from an image carrier for forming a black single-color image to a developing unit. 3. A color for forming a single color image for each color individually on an image carrier dedicated for each color by an electrophotographic process, and transferring the single color images in order to form a composite color image on a transfer member. In the image forming apparatus, a recycling mechanism that returns the colored toner collected by the cleaning unit from the image carrier that forms the first color monochromatic image to the developing unit, and a cleaning unit that cleans the image carrier that forms the black monochromatic image A color image forming apparatus comprising a recycle mechanism for returning the black toner collected in step (1) to the developing means.