JP2003215885A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an increase in the frequency of the maintenance of a particular one of image forming means, which result in an increase in the frequency of the maintenance of an image forming device, by preventing unequal consumption of image forming means even if a particular one of the image forming means is highly frequently used, thereby making the lives of the image forming means almost equal. <P>SOLUTION: Not only the developer capacity of a developing device 61BK of a black monochrome image forming means 18BK but also the diameter of a developing sleeve 65BK, the diameter of a stir screw 68BK, the peripheral length of an image carrier 40BK, an electrifier 60BK, the diameter of its electrifying roller, and a cleaner 63BK are made greater than the diameters of the developing sleeves 65Y, 65M, and 65C of the other monochrome image forming means 18Y, 18M, and 18C, the diameters of stir screws 68Y, 68M, and 68C, the peripheral lengths of image carriers 40Y, 40M, and 40C, electrifiers 60Y, 60M, and 60C, the diameters of their electrifying rollers, and cleaners 63Y, 63M, and 63C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine thereof. In particular, a plurality of image forming units that sequentially form a toner image on the image carrier by repeating charging, exposure, development, transfer, cleaning, etc. are arranged side by side along the conveyance direction of the transfer material such as an intermediate transfer body or a recording medium. The present invention relates to an electrophotographic or electrostatic recording type image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in a color image forming apparatus of this type, as described in, for example, Japanese Patent Laid-Open No. 9-160471, a charging device, an exposure device,
Equipped with developing device, transfer device, cleaning device, etc.
There is a so-called tandem type in which black, yellow, magenta, and cyan single-color image forming means are configured and a plurality of these single-color image forming means are arranged side by side along the conveyance direction of the medium conveyance belt.

In such a tandem type image forming apparatus, a transfer material which conveys black, yellow, magenta and cyan monochromatic images individually formed on the image carrier of each monochromatic image forming means by a medium conveying belt. Are sequentially transferred onto a recording medium, and then the transfer image is fixed by a fixing device, and
A composite color image was formed on a recording medium such as an OHP film.

However, in such an image forming apparatus, the developer capacity of the developing device, the developing sleeve diameter, the stirring screw diameter, and the monochromatic image forming of the monochromatic image forming means are provided for the purpose of sharing the parts. The peripheral length of the image carrier provided in the means, the size of the charging device provided in each single-color image forming means, the diameter of the charging roller, the cleaning device provided in each single-color image forming means, the diameter of the fur brush, etc. are formed to be equal. Was there.

[0005]

However, in this type of color image forming apparatus, a color image is not always output, but an image of only black is still output in many cases. For this reason, only the image carrier, the charging device, the developing device, and the cleaning device of the black monochromatic image forming means are quickly consumed,
There is a problem that only the maintenance frequency is increased, which in turn increases the maintenance frequency of the image forming apparatus, and the maintenance is troublesome.

Therefore, a first object of the present invention is to prevent uneven consumption of a plurality of image forming means even when a part of the image forming means is frequently used, and to provide a life of each image forming means. This is to prevent the frequency of maintenance of the image forming apparatus from increasing due to the frequency of maintenance of only some of the image forming units becoming substantially equal.

A second object of the present invention is to prevent uneven consumption of a plurality of single color image forming means even when a part of the single color image forming means is frequently used in a color image forming apparatus. Therefore, the lifespans of the respective monochromatic image forming means are made substantially equal to each other, and the maintenance frequency of a part of the monochromatic image forming means is increased to prevent the maintenance frequency of the image forming apparatus from increasing.

A third object of the present invention is to prevent uneven consumption of a plurality of single color image forming means even when one single color image forming means is frequently used especially in a color image forming apparatus. The lifespans of the respective single-color image forming units are made substantially equal to each other, and it is possible to prevent the maintenance frequency of the image forming apparatus from increasing because the maintenance frequency of one single-color image forming unit increases.

A fourth object of the present invention is to prevent uneven consumption of a plurality of monochromatic image forming means even when the black monochromatic image forming means is frequently used in a color image forming apparatus. The lifespans of the respective monochromatic image forming units are made substantially equal to each other, and the maintenance frequency of the image forming apparatus is prevented from increasing because the maintenance frequency of the black monochromatic image forming unit increases.

A fifth object of the present invention is, in particular, in a color image forming apparatus of a type in which an image is indirectly transferred from a plurality of monochromatic image forming means through an intermediate transfer member to form an image on a recording medium. Even when the frequency of using the monochrome image forming means is high,
Preventing uneven wear in a plurality of single-color image forming means so that the lifespans of the respective single-color image forming means are almost equal to each other, and the maintenance frequency of a part of the single-color image forming means is increased, and maintenance of the image forming apparatus is performed. It is to prevent the frequency from increasing.

A sixth object of the present invention is to prevent uneven consumption of a plurality of single color image forming means even when the black single color image forming means is frequently used, especially in a color image forming apparatus. The lifespans of the respective monochromatic image forming means are made substantially equal to each other, and only the maintenance frequency of the black monochromatic image forming means is increased, so that the maintenance frequency of the image forming apparatus is increased and the first time when the black image is formed. To speed up image formation.

A seventh object of the present invention is, in particular, in a color image forming apparatus of a type in which an image is directly transferred from a plurality of monochromatic image forming means without using an intermediate transfer member to form an image on a recording medium. Even when the single-color image forming means is frequently used, the uneven consumption of the plurality of single-color image forming means is prevented so that the lifespans of the respective single-color image forming means are almost equal to each other. It is to prevent the maintenance frequency of the image forming apparatus from increasing and the maintenance frequency of the image forming apparatus increases.

An eighth object of the present invention is to prevent uneven consumption of a plurality of monochromatic image forming means even when one monochromatic image forming means is frequently used, especially in a color image forming apparatus. The lifespans of the respective monochromatic image forming means are made substantially equal to each other, and it is possible to prevent the maintenance frequency of the image forming apparatus from increasing due to an increase in the maintenance frequency of only one monochromatic image forming means. The purpose is to improve the image quality by eliminating the color shift due to the color shift.

[0014]

Therefore, in order to achieve the above-mentioned first object, the invention according to claim 1 provides an image forming apparatus in which a plurality of image forming means are arranged along the transfer material conveying direction. The developer capacity of the developing device provided in the plurality of image forming units is different depending on the image forming unit.

According to a second aspect of the present invention, in order to achieve the above-mentioned second object, in the image forming apparatus according to the first aspect, a plurality of monochromatic image forming means are arranged as a plurality of image forming means, It is characterized in that the developer capacities of the developing devices provided for the plurality of monochromatic image forming means are different depending on the monochromatic image forming means.

According to a third aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the second aspect, one of the developing devices provided in the plurality of single-color image forming means is a single-color image forming device. The developer capacity of the developing device included in the image forming means is formed to be larger than the developer capacity of the developing device included in the other monochromatic image forming means.

According to a fourth aspect of the present invention, in order to achieve the above-mentioned fourth object, in the image forming apparatus according to the third aspect, the developer capacity of the developing device provided in the black monochromatic image forming means is It is characterized in that it is formed to have a larger capacity than the developer capacity of the developing device provided in the monochromatic image forming means of the color.

According to a fifth aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the third aspect, one of the developing devices provided in the plurality of single-color image forming means is a single-color image forming device. It is characterized in that the diameter of the developing sleeve of the developing device included in the image forming means is formed larger than the diameter of the developing sleeve of the developing device included in the other monochromatic image forming means.

According to a sixth aspect of the present invention, in order to achieve the third object described above, in the image forming apparatus according to the third aspect, one of the developing devices provided in the plurality of single-color image forming means is a single-color image forming device. It is characterized in that the diameter of the stirring screw of the developing device provided in the image forming means is made larger than the diameter of the stirring screw of the developing device provided in the other monochromatic image forming means.

According to a seventh aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the third aspect, one of the image carriers included in the plurality of single-color image forming means is a single color. It is characterized in that the peripheral length of the image carrier provided in the image forming unit is formed to be larger than the peripheral length of the image carrier provided in the other monochromatic image forming unit.

According to an eighth aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the third aspect, one of the charging devices provided in the plurality of single-color image forming means is a single-color image forming device. It is characterized in that the charging device provided in the image means is formed larger than the charging device provided in the other monochromatic image forming means.

According to a ninth aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the third aspect, one of the charging devices provided in the plurality of single-color image forming means is a single-color image forming device. It is characterized in that the charging roller diameter of the charging device provided in the image means is formed larger than the charging roller diameter of the charging device provided in the other monochromatic image forming means.

According to a tenth aspect of the present invention, in order to achieve the above-mentioned third object, in the image forming apparatus according to the third aspect, one of the cleaning devices provided in the plurality of single-color image forming means is used for a single-color operation. A cleaning device provided in the image means,
It is characterized in that it is formed to be larger than a cleaning device provided in another monochromatic image forming means.

In order to achieve the above-mentioned fifth object, the invention according to claim 11 is the image forming apparatus according to claim 2 or 3, wherein an intermediate transfer member is used as the transfer material, and the intermediate transfer member is An image formed on each image carrier of a plurality of monochromatic image forming means is sequentially superposed and primary-transferred, and then an image on the intermediate transfer member is secondarily transferred collectively to form an image on a recording medium. Is characterized by.

According to a twelfth aspect of the present invention, in order to achieve the sixth object described above, in the image forming apparatus according to the eleventh aspect, a black monochromatic image forming means is provided on the most downstream side in the transfer material conveying direction. It is characterized by arranging.

According to a thirteenth aspect of the invention, in order to achieve the seventh object described above, in the image forming apparatus according to the second or third aspect, the transfer material is electrostatically attached to a medium conveying belt. It is characterized in that a recording medium to be conveyed is used and an image formed on each image carrier of a plurality of monochromatic image forming means is sequentially transferred onto the recording medium to form an image.

According to a fourteenth aspect of the present invention, in order to achieve the eighth object described above, in the image forming apparatus according to the third aspect, the pitch lengths of the image bearing members provided in the plurality of monochromatic image forming means are set to: The intermediate transfer member is in the form of an endless belt, and is an integral multiple of the circumference of the drive roller that conveys the intermediate transfer member, or an integral multiple of the circumference of the drive roller that conveys the medium transfer belt.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall schematic configuration of a color copying machine which is an example of an image forming apparatus according to the present invention.

In the figure, reference numeral 100 is a copying machine main body, 200 is a paper feeding table on which the copying machine is mounted, 300 is a scanner mounted on the copying machine main body 100, and 400 is an automatic document feeder (ADF) further mounted thereon.

In the copying machine main body 100, an endless belt-shaped intermediate transfer member (transfer material) 10 is wound around a drive roller 14 and two driven rollers 15 and 16 in the example shown in the figure to make a timepiece in the figure. It is installed so that it can be rotated and conveyed around. of course,
Alternatively, the intermediate transfer member 10 may be wound around four or more rollers such as a roller that adjusts the offset. Although the intermediate transfer member 10 is stretched almost horizontally in the illustrated example, it may be stretched obliquely instead of horizontally.

In this illustrated example, a belt cleaning device 17 for removing the residual toner remaining on the intermediate transfer body 10 after the image transfer is provided on the left side of the one driven roller 15.

Further, on the intermediate transfer member 10 stretched between the driving roller 14 and the driven roller 15, four monochrome image forming means 18 of yellow, magenta, cyan and black are laterally arranged along the conveying direction. The tandem image forming device 20 is provided side by side. An exposure device 21 is further provided on the tandem image forming device 20.

On the other hand, a secondary transfer device 22 is provided below the stretched area of the intermediate transfer member 10. Secondary transfer device 22
In the illustrated example, the secondary transfer belt 24, which is an endless belt, is stretched between two rollers 23, and is pressed against the other driven roller 16 to transfer the image on the intermediate transfer body 10 to a recording medium. To do.

Next to the secondary transfer device 22, a fixing device 25 for fixing the transferred image on the recording medium is provided. Fixing device 2
Reference numeral 5 denotes a fixing belt 26 which is an endless belt, and a pressure roller 2
Press 7 to configure. And, in the illustrated example, a part thereof may be provided by being inserted below the stretched region of the intermediate transfer member 10, although it may be all.

The above-mentioned secondary transfer device 22 also has a medium carrying function of carrying the recording medium after the image transfer to the fixing device 25. Of course, a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to additionally provide this medium carrying function.

Under the secondary transfer device 22 and the fixing device 25, the recording medium is reversed so as to form images on both sides of the recording medium in parallel with the extending direction of the intermediate transfer body 10. A medium reversing device 28 is provided.

By the way, when making a copy using this color copying machine, a document is set on the document table of the automatic document feeder 400. Alternatively, the automatic document feeder 40
0 is opened, a document is set on the contact glass of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.

When a start switch (not shown) is pressed, when the original is set on the automatic original feeder 400, the original is conveyed and moved onto the contact glass, and then the scanner 300 is driven to move the original contents. To read.

When a start switch (not shown) is pressed, the drive roller 14 is rotationally driven by a drive motor (not shown), and the driven rollers 15 and 16 are driven to rotate.
Is conveyed by rotation. At the same time, the image carrier 40 is rotated by the individual monochrome image forming means 18 to form a yellow, magenta, cyan, and black monochrome image on each image carrier 40. Then, as the intermediate transfer body 10 is conveyed, the monochromatic images are sequentially superposed and primary-transferred to perform intermediate transfer body 10 transfer.
Form a composite color image on top.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the recording medium is fed out from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages. , Separation roller 45
Separate the sheets one by one and put them in the paper feed path 46.
And guides it to the paper feed path 48 in the main body 100 of the copying machine, and abuts against the registration roller 49 to stop it.

Alternatively, the paper feed roller 50 is rotated to feed out the recording medium on the manual feed tray 51, and the recording paper is separated one by one by the separation roller 52 and put into the manual paper feed path 53, and also abutted against the registration roller 49 and stopped. .

Then, the registration roller 49 is rotated in synchronism with the composite color image on the intermediate transfer member 10 to feed the recording medium between the intermediate transfer member 10 and the secondary transfer device 22, and the secondary transfer device 22. Then, the combined color image on the intermediate transfer member 10 is secondarily transferred all together to form a color image on the recording medium.

At the secondary transfer portion, a negative bias voltage, for example, -800 to -2000 V is applied to the back surface of the transfer material.
Is applied, and a pressure of, for example, about 50 N / cm ² is applied. The toner of the intermediate transfer member 10 is attracted to the recording medium by the electrostatic force and the pressure due to the electric field generated by the applied voltage, and is collectively transferred to the transfer material (secondary transfer).

The recording medium after the image transfer is the secondary transfer device 2
2 and conveys to the fixing device 25, and the fixing device 25
After heat and pressure are applied to fix the transferred image, the switching claw 5
5 and the discharge roller 56 to discharge, and the discharge tray 5
Stack on 7. Alternatively, the sheet is switched by the switching claw 55 and placed in the recording medium reversing device 28, reversed there and guided to the transfer position again, and after forming an image on the back surface, the sheet is discharged onto the sheet discharge tray 57 by the discharge roller 56.

On the other hand, in the intermediate transfer body 10 after the image transfer, the belt cleaning device 17 removes the residual toner remaining on the intermediate transfer body 10 after the image transfer and prepares for the image formation again by the tandem image forming device 20. .

In the tandem image forming device 20 described above, each of the monochromatic image forming means 18 is, in detail, for example, as shown in FIG. 2, a charging device 60 and a developing device around a drum-shaped image carrier 40. 61, a primary transfer device 62, a cleaning device 63, a neutralization device 64, and the like. The image carrier 40 has a drum shape in the illustrated example, but may have an endless belt shape.

Although not shown, these monochromatic image forming means 18
It is also possible to form a process cartridge with all or a part of the above-mentioned parts and collectively attach to and detach from the copying machine main body 100 to improve maintainability.

Of the parts constituting the monochromatic image forming means 18,
The charging device 60 uses a charging roller in the illustrated example, and charges the image carrier 40 by contacting the image carrier 40 and applying a voltage thereto.

The developing device 61 uses a two-component developer composed of a magnetic carrier and a non-magnetic toner in the illustrated example.
Then, the stirring unit 66 that conveys the two-component developer while stirring and adheres to the developing sleeve 65, and the developing unit that transfers the toner of the two-component developer adhered to the developing sleeve 65 to the image carrier 10. 67 and its developing section 6
The stirrer 66 is set to a position lower than 7

The stirring section 66 is provided with two parallel stirring screws 68. A partition plate 69 separates the two stirring screws 68 except for both ends. Also, the developing case 7
The toner density sensor 71 is attached to 0.

On the other hand, in the developing section 67, the developing sleeve 65 is provided so as to face the image carrier 40 through the opening of the developing case 70.
And the magnet 72 is fixedly provided in the developing sleeve 65. In addition, the developing sleeve 65
The doctor blade 73 is provided with its tip approaching.

Then, the two-component developer is conveyed and circulated while being stirred by the two stirring screws 68, and is supplied to the developing sleeve 65. The developer supplied to the developing sleeve 65 is drawn up and held by the magnet 72, and the developing sleeve 6
Form a magnetic brush on 5. With the rotation of the developing sleeve 65, the magnetic brush cuts an appropriate amount by the doctor blade 73. The developer that has been cut off is returned to the stirring unit 66.

On the other hand, the developer on the developing sleeve 65 is transferred to the image carrier 40 to visualize the electrostatic latent image on the image carrier 40. After the visible image is formed, the developer remaining on the developing sleeve 65 is separated from the developing sleeve 65 and returns to the stirring unit 66 in the absence of the magnetic force of the magnet 72. By repeating this, when the toner density in the stirring section 66 becomes low, the toner density sensor 71 detects it and supplies the toner to the stirring section 66.

The primary transfer device 62 has a roller shape, and is provided by pressing the intermediate transfer member 10 against the image carrier 40.
Alternatively, the charger is not limited to the roller shape and may be a non-contact charger.

The cleaning device 63 is equipped with a cleaning blade 75 made of, for example, polyurethane rubber, the tip of which is pressed against the image bearing member 40, and the outer periphery of the cleaning blade 75 is brought into contact with the image bearing member 40, and a conductive fur brush 76 is indicated by an arrow. Prepare to rotate in any direction. Further, a metal electric field roller 77 that applies a bias to the fur brush 76 is rotatably provided in the direction of the arrow, and the tip of the scraper 78 is pressed against the electric field roller 77. Further, a recovery screw 79 for recovering the removed toner is provided.

Then, the fur brush 76 rotating in the counter direction with respect to the image carrier 40 removes the residual toner on the image carrier 40. The toner attached to the fur brush 76 is removed by the electric field roller 77 that rotates in the counter direction with respect to the fur brush 76 and applies a bias. The electric field roller 77 is cleaned by a scraper 78. The removed toner is conveyed by a recovery screw 79 to a waste toner bottle (not shown) or returned to the developing device 61 for reuse.

The static eliminator 64 is, for example, a lamp and irradiates light to initialize the surface potential of the image carrier 40.

Then, as the image carrier 40 rotates, the surface of the image carrier 40 is uniformly charged by the charging device 60.
Then, according to the contents read by the scanner 300, the above-mentioned exposure device 21 irradiates the writing light L from a laser, an LED or the like to form an electrostatic latent image on the image carrier 40.

Thereafter, the developing device 61 attaches toner to make the electrostatic latent image visible, and the primary transfer device 62 transfers the visible image onto the intermediate transfer member 10. The surface of the image carrier 40 after the image transfer is cleaned by the cleaning device 63 to remove residual toner, and the charge is removed by the charge removing device 64 to prepare for another image formation.

By the way, in the illustrated tandem image forming device 20, as shown in detail in FIG. 3, four monochromatic image forming means 18Y, 18M, yellow, magenta, cyan and black are formed.
18C and 18BK are arranged in order along the conveyance direction of the intermediate transfer body 10 which is a transfer material as shown in the figure so that the black monochromatic image forming means 18BK is located on the most downstream side.

At this time, the image carriers 40Y and 40 provided in the yellow and magenta monochromatic image forming means 18Y and 18M, respectively.
Monochromatic image forming means 18M for each of M and magenta and cyan
The image carrier 40C provided in 18C has the same pitch length L1 between the image carriers 40M and 40C, and the image carrier 40C provided in each of the monochrome image forming means 18C and 18BK for cyan and black.
・ A pitch length L2 larger than 40BK is set.

Then, four monochrome image forming means 18Y, 18M, 18C, and 1 for yellow, magenta, cyan, and black.
Development device 61Y / 61M / 61C / 61 for 8BK
Of the BKs, the developer capacity of the developing device 61BK provided in the black monochromatic image forming unit 18BK is set to the other monochromatic image forming unit 18Y.
・ Development device 61Y ・ 61M ・ 6 for 18M ・ 18C
It is formed larger than the developer capacity of 1C.

In the illustrated example, black monochromatic image forming means 18BK
Of the developing device 61BK, the diameter of the developing sleeve 65BK, the diameter of the stirring screw 68BK,
The peripheral length of the image carrier 40BK, the charging device 60BK, the diameter of the charging roller thereof, and the cleaning device 63BK are respectively provided in the other monochromatic image forming means 18Y, 18M, and 18C, the diameter of the developing sleeves 65Y, 65M, and 65C, and the stirring screw 68Y.
・ 68M ・ 68C diameter, image carrier 40Y ・ 40M ・ 40
The peripheral length of C, the charging devices 60Y, 60M, and 60C, the diameter of the charging roller, and the cleaning devices 63Y, 63M, and 63C are formed to be larger.

In the above-described example, the present invention is applied to an image forming apparatus using the intermediate transfer body 10 as a transfer material, and the intermediate transfer body 10 has four monochromatic image forming means 18Y.
・ 18M ・ 18C ・ 18BK image carrier 40Y ・ 40
After the images formed on the M, 40C, and 40BK are sequentially superimposed and primary-transferred, the images on the intermediate transfer body 10 are collectively transferred to 2
The case of forming the image on the recording medium by the subsequent transfer has been described.

However, the present invention, as shown in FIG.
As a transfer material, a recording medium that is electrostatically attached to the medium conveying belt 80 and is conveyed is used, and the image bearing members 40Y and 40M of the plurality of monochromatic image forming units 18Y, 18M, 18C, and 18BK are used on the recording medium. It can also be applied to an image forming apparatus that directly and sequentially transfers images formed on 40C and 40BK to form images.

That is, also in the tandem image forming device 20 of this example, four monochromatic image forming means 18Y, 18M, 18C and 18BK of yellow, magenta, cyan and black are conveyed as shown in the figure of a recording medium which is a transfer material. In order along the direction,
The black monochromatic image forming means 18BK is arranged so as to be located on the most downstream side.

At this time, the image carriers 40Y and 40 provided in the yellow and magenta monochromatic image forming means 18Y and 18M, respectively.
Monochromatic image forming means 18M for each of M and magenta and cyan
The image carrier 40C provided in 18C has the same pitch length L1 between the image carriers 40M and 40C, and the image carrier 40C provided in each of the monochrome image forming means 18C and 18BK for cyan and black.
・ A pitch length L2 larger than 40BK is set.

Then, four monochrome image forming means 18Y, 18M, 18C, and 1 for yellow, magenta, cyan, and black.
Development device 61Y / 61M / 61C / 61 for 8BK
Of the BKs, the developer capacity of the developing device 61BK provided in the black monochromatic image forming unit 18BK is set to the other monochromatic image forming unit 18Y.
・ Development device 61Y ・ 61M ・ 6 for 18M ・ 18C
It is formed larger than the developer capacity of 1C.

Also in the image forming apparatus of this example, not only the developer capacity of the developing device 61BK provided in the black monochromatic image forming means 18BK, but also the diameter of the developing sleeve 65BK, the diameter of the stirring screw 68BK, and the peripheral length of the image carrier 40BK. , Charging device 60
BK, its charging roller diameter, cleaning device 63BK
Respectively other monochromatic image forming means 18Y, 18M, 18C
For developing sleeves 65Y / 65M / 65C, stirring screws 68Y / 68M / 68C, image carrier 40
Perimeter of Y ・ 40M ・ 40C, charging device 60Y ・ 60M ・
60C, its charging roller diameter, cleaning device 63Y
Larger than 63M and 63C.

In the illustrated example, the medium carrying belt 80 is wound around a driving roller 81 and two driven rollers 82, and is carried counterclockwise as shown by the arrow in the drawing, and the registration roller 49 is used.
Then, the recording medium sent out at a timing is electrostatically attached and conveyed.

As described above, the developer capacity of the developing device 61BK provided in the black monochromatic image forming means 18BK, etc. is provided in the monochromatic image forming means 18 of other colors.
When the toner is formed larger than the developer capacity of 18M and 18C, especially in a color image forming apparatus, when the black monochromatic image forming means 18BK is frequently used, the black monochromatic image forming means 18BK which is frequently used is used. By increasing the developer capacity of the developing device 61BK provided in the above, the uneven consumption of the plurality of monochromatic image forming means 18Y, 18M, 18C, and 18BK is prevented, and the lifespan of the respective monochromatic image forming means is substantially equalized. In addition, it is possible to prevent the maintenance frequency of the image forming apparatus from increasing because the maintenance frequency of the black monochromatic image forming unit 18BK increases.

Now, in the example shown in FIGS. 1 to 3, when the peripheral length of the driving roller 14 that conveys the endless belt-shaped intermediate transfer member 10 is Lr1, it is preferable that L1 = L2 / n1 = n2 × Lr1. . Here, n1 and n2 are integers.

Also in the example shown in FIG. 4, when the peripheral length of the drive roller 81 which conveys the medium conveying belt 80 is Lr2, it is preferable that L1 = L2 / n3 = n4 × Lr2. Here, n3 and n4 are integers.

In this way, the belt speed fluctuation cycle due to the eccentricity of the driving rollers 14 and 81 for driving the belts is set in the same phase among the image carriers 40Y, 40M, 40C and 40BK to eliminate color misregistration. Therefore, high image quality can be achieved.

[0075]

As described above, according to the first aspect of the invention, since the developer capacity of the developing device provided in the plurality of image forming means differs depending on the image forming means, use of a part of the image forming means is required. When the frequency is high, by increasing the developer capacity of the developing device provided in the image forming means that is frequently used,
The uneven consumption of a plurality of image forming units is prevented so that the lifespans of the image forming units are almost equal to each other, and only some of the image forming units have a high maintenance frequency, which increases the maintenance frequency of the image forming apparatus. Can be prevented.

According to the second aspect of the invention, a plurality of monochromatic image forming means are arranged as a plurality of image forming means, and the developer capacity of the developing device provided in the plurality of monochromatic image forming means is set to the monochromatic image forming means. Since the difference depends on the means, especially in a color image forming apparatus, when a part of the monochromatic image forming means is frequently used, the developer capacity of the developing device provided in the monochromatic image forming means which is frequently used is increased. As a result, uneven consumption of a plurality of monochromatic image forming means is prevented so that the lifespans of the monochromatic image forming means are almost equal to each other, and the maintenance frequency of a part of the monochromatic image forming means is increased, resulting in image formation. It is possible to prevent the maintenance frequency of the device from increasing.

According to the third aspect of the invention, among the developing devices provided in the plurality of monochromatic image forming means, the developer capacity of the developing device provided in one monochromatic image forming means is provided in the other monochromatic image forming means. Since the toner is formed larger than the developer capacity of the developing device, especially in a color image forming apparatus, when one monochromatic image forming device is frequently used, the developing device provided for the monochromatic image forming device which is frequently used is developed. Increasing the agent capacity prevents uneven wear in the plurality of single-color image forming means so that the lifespans of the respective single-color image forming means become substantially equal, and the maintenance frequency of one single-color image forming means increases. hand,
It is possible to prevent the maintenance frequency of the image forming apparatus from increasing.

According to the invention of claim 4, the developer capacity of the developing device provided in the black monochromatic image forming means is made larger than the developer capacity of the developing device provided in the monochromatic image forming means of other colors. In particular, in a color image forming apparatus, when the black single-color image forming means is frequently used, by increasing the developer capacity of the developing device provided in the frequently-used black single-color image forming means, The uneven consumption of the single color image forming means is prevented so that the lifespan of the respective single color image forming means becomes almost equal, and only the maintenance frequency of the black single color image forming means increases, and the maintenance frequency of the image forming apparatus increases. It can be prevented from increasing.

According to the invention of claim 5, of the developing devices provided in the plurality of monochromatic image forming means, the developing sleeve diameter of the developing device provided in one monochromatic image forming means is provided in the other monochromatic image forming means. Since the diameter is formed larger than the diameter of the developing sleeve of the developing device, especially in a color image forming apparatus, when one monochromatic image forming device is frequently used, the developing device provided for the monochromatic image forming device which is frequently used is developed. By increasing the developing sleeve diameter together with the developer capacity, uneven wear in a plurality of monochromatic image forming means is prevented, and the lifespan of each monochromatic image forming means is almost equalized. It is possible to prevent the maintenance frequency of the image forming apparatus from increasing due to the increase in the number of maintenance.

According to the sixth aspect of the invention, among the developing devices provided in the plurality of monochromatic image forming means, the stirring screw diameter of the developing device provided in one monochromatic image forming means is provided in the other monochromatic image forming means. Since the diameter is formed larger than the stirring screw diameter of the developing device, especially in a color image forming apparatus, when one monochromatic image forming device is frequently used, the developing device provided for the monochromatic image forming device which is frequently used is developed. By increasing the agent volume and the stirring screw diameter, it is possible to prevent uneven consumption of a plurality of single-color image forming means so that the respective lifespans of the single-color image forming means become substantially equal to each other. It is possible to prevent the maintenance frequency of the image forming apparatus from increasing due to the increase in the number of maintenance.

According to the seventh aspect of the present invention, among the image carriers included in the plurality of monochromatic image forming units, the perimeter of the image carrier included in one monochromatic image forming unit is changed to the other monochromatic image forming unit. Since it is formed to be larger than the peripheral length of the image carrier provided, especially in a color image forming apparatus, when one monochromatic image forming device is frequently used, the developing device provided in the monochromatic image forming device having the high frequency of use is used. By increasing the perimeter of the image carrier together with the developer capacity, it is possible to prevent uneven consumption of a plurality of monochromatic image forming means so that the lifespans of the monochromatic image forming means become substantially equal to each other. It is possible to prevent the maintenance frequency of the image forming apparatus from increasing as the maintenance frequency of the unit increases.

According to the invention of claim 8, of the charging devices provided in the plurality of single-color image forming means, the charging device provided in one single-color image forming means is larger than the charging devices provided in the other single-color image forming means. In particular, in a color image forming apparatus, when one monochromatic image forming device is frequently used, the charging device is increased together with the developer capacity of the developing device provided in the monochromatic image forming device which is frequently used. As a result, the uneven consumption of the plurality of single color image forming means is prevented, the lifespans of the respective single color image forming means are substantially equalized, and the maintenance frequency of one single color image forming means is increased. It is possible to prevent the maintenance frequency from increasing.

According to the invention of claim 9, among the charging devices provided in the plurality of single-color image forming means, the charging roller diameter of the charging device provided in one single-color image forming means is provided in the other single-color image forming means. Since the diameter is formed larger than the diameter of the charging roller of the charging device, particularly in a color image forming apparatus, when one single-color image forming device is frequently used, the developing device provided for the frequently-used single-color image forming device is used. By increasing the charging roller diameter of the charging device together with the agent capacity, it is possible to prevent uneven consumption of a plurality of single-color image forming means so that the lifespan of the respective single-color image forming means becomes substantially equal to each other. It is possible to prevent the maintenance frequency of the image forming apparatus from increasing and the maintenance frequency of the image forming apparatus increasing.

According to the tenth aspect of the present invention, among the cleaning devices provided in the plurality of monochromatic image forming means, the cleaning device provided in one monochromatic image forming device is larger than the cleaning device provided in the other monochromatic image forming device. Because it forms
Particularly in a color image forming apparatus, when one monochromatic image forming unit is frequently used, a plurality of cleaning units are provided together with the developer capacity of the developing device provided in the monochromatic image forming unit which is frequently used. Of the monochromatic image forming means so that the life of the monochromatic image forming means is almost the same, the maintenance frequency of one monochromatic image forming means increases, and the maintenance frequency of the image forming apparatus increases. It can be prevented from increasing.

According to the eleventh aspect of the present invention, the intermediate transfer member is used as the transfer material, and the images formed on the image bearing members of the plurality of monochromatic image forming units are sequentially superposed on the intermediate transfer member. After that, the images on the intermediate transfer body are collectively secondarily transferred to form an image on the recording medium. In particular, the recording medium is indirectly transferred from a plurality of single-color image forming means through the intermediate transfer body. In a color image forming apparatus of the type that forms an image on a substrate, even when some monochromatic image forming means are frequently used,
Preventing uneven wear in a plurality of single-color image forming means so that the lifespans of the respective single-color image forming means are almost equal to each other, and the maintenance frequency of a part of the single-color image forming means is increased, and maintenance of the image forming apparatus is performed. It is possible to prevent the frequency from increasing.

According to the twelfth aspect of the invention, since the black monochromatic image forming means is arranged on the most downstream side in the transfer material conveying direction, the frequency of use of the black monochromatic image forming means is particularly high in a color image forming apparatus. Even when there are many, it is possible to prevent uneven wear in the plurality of single-color image forming means so that the life of each single-color image forming means is almost equal, and only the maintenance frequency of the black single-color image forming means increases. The maintenance frequency of the image forming apparatus can be increased. Further, in the image forming apparatus using the intermediate transfer member, by shortening the distance from the primary transfer to the secondary transfer, it is possible to speed up the first image formation when forming a black image.

According to the thirteenth aspect of the present invention, as the transfer material, a recording medium which is electrostatically attached to the medium conveying belt and is conveyed is used, and the recording medium carries each image of a plurality of monochromatic image forming means. Since the images formed on the body are sequentially transferred to form an image, in particular, a color image of a type in which images are directly transferred from a plurality of single color image forming means without using an intermediate transfer body to form an image on a recording medium. In the forming apparatus, even when a part of the monochromatic image forming means is frequently used, uneven consumption of the plurality of monochromatic image forming means is prevented so that the lifespan of the monochromatic image forming means becomes almost equal. It is possible to prevent the maintenance frequency of the image forming apparatus from increasing due to the frequent maintenance frequency of the single-color image forming unit.

According to the fourteenth aspect of the present invention, the pitch length of the image bearing members provided in the plurality of monochromatic image forming units is set to the circumferential length of the drive roller which conveys the intermediate transfer member with the endless belt as the intermediate transfer member. Or an integral multiple of the circumference of the drive roller that conveys the medium conveying belt. Therefore, in a color image forming apparatus, even when the single-color image forming unit is frequently used, a plurality of single-color image forming means are used. The uneven consumption of the image forming means is prevented so that the lifespans of the single color image forming means are substantially equal to each other, and the maintenance frequency of one single color image forming means increases, and the maintenance frequency of the image forming apparatus increases. It is possible to prevent this, and to eliminate the color shift due to the eccentricity of the belt driving roller, thereby improving the image quality.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram of a color copying machine which is an example of an image forming apparatus according to the present invention.

FIG. 2 is a partially enlarged configuration diagram of a tandem image forming device provided in the color copying machine.

FIG. 3 is an overall configuration diagram of the tandem image forming apparatus.

FIG. 4 is an overall schematic configuration diagram of a tandem image forming apparatus provided in a color copying machine which is another example of the image forming apparatus according to the present invention.

[Explanation of symbols]

10 Intermediate Transfer Body (Transfer Material) 14 Drive Roller Conveying Intermediate Transfer Body 18, 18Y, 18M, 18C, 18BK Single Color Image Forming Means 20 Tandem Image Forming Device 40, 40Y, 40M, 40C, 40BK Image Carrier 60, 60Y・ 60M ・ 60C ・ 60BK Charging device 61 ・ 61Y ・ 61M ・ 61C ・ 61BK Developing device 63 ・ 63Y ・ 63M ・ 63C ・ 63BK Cleaning device 65 ・ 65Y ・ 65M ・ 65C ・ 65BK Developing sleeve 68 ・ 68Y ・ 68M ・ 68C ・ 68BK Agitation screw 80 Medium transport belt 81 Drive roller L1 for transporting the medium transport belt Pitch length L2 Pitch length

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/08 112 112 G03G 15/08 112 501 501 501D 503 503Z 507 507E 21/10 21/00 310 F term (reference) ) 2H030 AA06 AB02 AD02 AD03 BB22 BB42 BB43 BB63 BB71 2H077 AA12 AB02 AD14 GA12 2H134 GA01 GB02 KJ02 2H200 FA12 FA17 FA19 GA12 GA23 GA49 GB11 HB12 HB22 JC03 JC09

Claims (14)

[Claims] 1. In an image forming apparatus in which a plurality of image forming units are arranged along a transfer material conveying direction, a developer capacity of a developing device provided in the plurality of image forming units is different depending on the image forming unit. An image forming apparatus characterized by: 2. A plurality of monochromatic image forming means are arranged as the plurality of image forming means, and a developer capacity of a developing device provided in the plurality of monochromatic image forming means is different depending on the monochromatic image forming means. The image forming apparatus according to claim 1. 3. A developer capacity of a developing device included in one monochromatic image forming means out of a developer capacity of a developing device included in another monochromatic image forming means among the developing devices included in the plurality of monochromatic image forming means. The image forming apparatus according to claim 2, wherein the image forming apparatus is formed large. 4. The developer capacity of the developing device provided in the black monochromatic image forming means is formed to be larger than the developer capacity of the developing device provided in the monochromatic image forming means of another color. The image forming apparatus according to item 1. 5. A developing sleeve diameter of a developing device included in one monochromatic image forming means among developing devices included in the plurality of monochromatic image forming means is smaller than a developing sleeve diameter of a developing device included in another monochromatic image forming means. The image forming apparatus according to claim 3, wherein the image forming apparatus is formed large. 6. The developing device provided in one of the plurality of single-color image forming units has a stirring screw diameter of a developing device provided in one of the single-color image forming units is smaller than a stirring screw diameter of developing devices provided in the other single-color image forming units. The image forming apparatus according to claim 3, wherein the image forming apparatus is formed large. 7. A perimeter of an image carrier included in one of the plurality of monochromatic image forming means and a perimeter of an image carrier included in another of the monochromatic image forming means. The image forming apparatus according to claim 3, wherein the image forming apparatus is formed larger. 8. A charging device included in one of the plurality of single-color image forming units is formed larger than a charging device included in another of the single-color image forming units. The image forming apparatus according to claim 3. 9. A charging roller diameter of a charging device provided in one single color image forming means among charging devices provided in the plurality of single color image forming means is smaller than a charging roller diameter of a charging device provided in another single color image forming means. A large size is formed, It is characterized by the above-mentioned.
The image forming apparatus according to item 1. 10. The cleaning device provided in one monochromatic image forming unit among the cleaning devices provided in the plurality of monochromatic image forming units is formed larger than the cleaning devices provided in the other monochromatic image forming units. The image forming apparatus according to claim 3. 11. An intermediate transfer member is used as the transfer material,
The images formed on the image bearing members of the plurality of monochromatic image forming means are sequentially superposed on the intermediate transfer member, and firstly transferred, and then the images on the intermediate transfer member are collectively secondarily transferred and recorded. The image forming apparatus according to claim 2, wherein the image is formed on a medium. 12. The image forming apparatus according to claim 11, wherein the black monochromatic image forming unit is arranged on the most downstream side in the transporting direction of the transfer material. 13. A transfer medium, which is a recording medium electrostatically attached to a medium transfer belt for transfer, is used, and an image formed on each image carrier of the plurality of single-color image forming means is used as the transfer medium. The image forming apparatus according to claim 2, wherein the images are formed by sequentially transferring the images. 14. A pitch length of an image carrier provided in each of the plurality of monochromatic image forming units is an integral multiple of a circumferential length of a driving roller which conveys the intermediate transfer member in the form of an endless belt. The image forming apparatus according to claim 3, wherein the driving roller that conveys the medium conveying belt has an integral multiple of the circumferential length.