JP2001356550A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a color image forming device that the device can be miniaturized and the installation space can be reduced. SOLUTION: This color image forming device is composed so that an intermediate transfer body 5 is moved to downward in the vertical direction from above, and to photosensitive drums 3M, 3C, 3Y and 3Bk, are disposed along the surface moving in this direction, and moreover developing rollers 52M, 52C, 52Y and 52Bk are opposite to the photosensitive drums 3M, 3C, 3Y and 3Bk. Below the developing rollers 52B, 52C, 52Y and 52Bk, layer thickness controlling blades 54M, 54C, 54Y and 54Bk are brought into contact therewith. A non-magnetic 1 component developer is used as the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique of a color image forming apparatus for forming a color image by arranging a developer carrying member for carrying a developer of each color along a moving direction of an intermediate transfer body. Belongs to the field.

[0002]

2. Description of the Related Art Conventionally, as a color image forming apparatus, cyan, magenta, yellow and black toners are used.
There is a so-called tandem type color image forming apparatus in which different developing units are accommodated in different developing units and these developing units are arranged in a vertical direction or a horizontal direction.

In this tandem-type color image forming apparatus, since each developing device containing the toner of each color can perform the developing operation substantially simultaneously, a color image can be formed at an extremely high speed.

[0004]

However, in a conventional tandem type color image forming apparatus, a plurality of process units each including a photosensitive drum and a developing device are juxtaposed substantially in parallel with the installation surface of the color image forming apparatus. In this case, there is a problem that the installation area becomes large.

[0005] Therefore, an apparatus in which the installation area is reduced by arranging the plurality of process units in a vertical direction is disclosed in, for example, JP-A-08-190245.

However, in the method disclosed in the above-mentioned publications, the discharge tray protrudes from the side of the apparatus, or the configuration of each developing unit is complicated and large, so that the entire color image forming apparatus is small. It was difficult to convert.

Accordingly, an object of the present invention is to provide a color image forming apparatus capable of solving such problems and reducing the installation area and the overall size of the apparatus.

[0008]

According to a first aspect of the present invention, there is provided a color image forming apparatus, comprising: a belt-like intermediate transfer member provided so that a surface thereof moves in a substantially vertical direction; A plurality of electrostatic latent image carriers arranged side by side in a substantially vertical direction along the direction of movement of the surface; and a plurality of developing devices arranged to face each of the plurality of electrostatic latent image carriers. A plurality of developing means including a developer carrier and a plurality of layer thickness regulating members provided so as to be in contact with each of the plurality of developer carriers; A plurality of charging means arranged to perform the charging, a plurality of exposure means for exposing respective charged areas of the plurality of electrostatic latent image carriers, and the plurality of electrostatic latent image carrying means of the intermediate transfer body. The surface facing the body moves vertically upwards to downwards The plurality of developing means are developing means using a non-magnetic one-component developer as a developer, and the plurality of layer thickness regulating members are more vertical than the plurality of developer carrying members. It is provided below the direction.

According to the color image forming apparatus of the present invention, each of the plurality of electrostatic latent image carriers is charged by the plurality of charging means and is further exposed by the plurality of exposure means, so that the plurality of electrostatic latent image carriers are exposed. An electrostatic latent image is formed on the electrostatic latent image carrier. These electrostatic latent images are developed using a plurality of developers of different colors by a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers. Then, the developer images of each color developed in this manner are transferred to the surface of the intermediate transfer body whose surface moves in the direction in which the plurality of electrostatic latent image carriers are juxtaposed.

Here, the surface of the intermediate transfer member facing the plurality of electrostatic latent image carriers is set so as to move from the upper side in the vertical direction to the lower side. The electro-latent image carrier is also located at a position facing the intermediate transfer member.
It moves from the vertical top to the bottom. Therefore, the charging unit, the exposing unit, the developing unit, and the like are located on the downstream side in the moving direction of the plurality of electrostatic latent image carriers, from a position where the intermediate transfer member faces the plurality of electrostatic latent image carriers. Will be located. As a result, at a position below the plurality of electrostatic latent image carriers, an arrangement space for the charging unit, the exposure unit, and the like is secured, so that the plurality of layer thickness regulating members are
Provided below the plurality of developer carrying members in the vertical direction,
By arranging it on the arrangement space side, it is possible to reduce the size of the upper part of the plurality of developer carrying members.

As described above, a space for arranging each means is secured below the plurality of electrostatic latent image carriers, and the size of the upper portion of the plurality of developer carriers is reduced.
When the plurality of electrostatic latent image carriers and the plurality of developer carriers are arranged vertically in the vertical direction, it is possible to reduce the adjacent distance in the vertical direction, and as a result, the overall size of the color image forming apparatus is reduced. To achieve. Furthermore, since the plurality of developing means are developing means using a non-magnetic one-component developer as a developer, they can be realized with a simple configuration, and the developing means itself can be reduced in size. As a result, the size of the entire color image forming apparatus can be further reduced.

According to a second aspect of the present invention, in the color image forming apparatus of the first aspect, the developer is a polymerized toner prepared by a suspension polymerization method. It is characterized by.

According to the color image forming apparatus of the present invention, since the developer is a polymerized toner formed by a suspension polymerization method, the layer thickness regulating member is disposed below the developer carrier as described above. Even in this case, due to the high fluidity of the polymerized toner, the toner scraped by the layer thickness regulating member can be prevented from staying without being circulated, and the occurrence of printing failure due to the staying can be surely suppressed.

According to a third aspect of the present invention, there is provided a color image forming apparatus according to the second aspect, wherein the developer images are formed on each of the plurality of electrostatic latent image carriers. After transferring to the intermediate transfer member,
The image forming apparatus is characterized in that the developer remaining on each electrostatic latent image carrier is collected by each of the plurality of developer carriers through charging and exposure together with movement of each electrostatic latent image carrier. And

According to the color image forming apparatus of the present invention, after transferring the developer images formed on each of the plurality of electrostatic latent image carriers to the intermediate transfer member, each of the plurality of electrostatic latent image carriers is transferred. The developer remains on the body, and the residual developer is recovered by each of the plurality of developer carriers through charging and exposure together with the movement of each electrostatic latent image carrier. Accordingly, since it is not necessary to provide a large container for collecting the transfer residual developer, the size of the image forming apparatus can be reduced.
In particular, when a polymerized toner having high fluidity is used, the transfer residual toner itself can be reduced, and it is easy to realize such a method of collecting the transfer residual developer.

According to a fourth aspect of the present invention, there is provided a color image forming apparatus according to the third aspect, wherein each of the electrostatic images is transferred after transferring the developer image to the intermediate transfer member. A plurality of cleaning rollers that temporarily hold the developer remaining on the latent image carrier using an electric field,
It is provided below each of the electrostatic latent image carriers in the vertical direction.

According to the color image forming apparatus of the present invention, after the developer image is transferred to the intermediate transfer member, the developer remains on each of the electrostatic latent image carriers. The developer is temporarily held by a plurality of cleaning rollers by the action of an electric field. And the reserved developer is
It can be collected by returning to the electrostatic latent image carrier during non-image formation. Therefore, even if the amount of the transfer residual developer increases,
It surely prevents it from appearing on prints. Further, since the plurality of cleaning rollers are provided below each of the electrostatic latent image carriers in the vertical direction, the developer attached to the cleaning rollers drops onto the electrostatic latent image carrier by weight. Therefore, printing failure due to the falling developer is reliably prevented.

According to a fifth aspect of the present invention, there is provided a color image forming apparatus according to any one of the first to fourth aspects, wherein a transfer medium supply tray for supplying a transfer medium is provided. A transfer medium discharge tray on which a transfer medium discharged after completion of the image forming step is placed, and a visible image forming unit including the intermediate transfer member, the plurality of electrostatic latent image carriers, and the plurality of developing units Is provided vertically below the transfer medium discharge tray and vertically above the transfer medium supply tray.

According to the color image forming apparatus of the present invention, the visible image forming means including the intermediate transfer body, the plurality of electrostatic latent image carriers, and the plurality of developing means is provided in the transfer medium discharge tray. Since it is provided vertically below the transfer medium supply tray and vertically above the transfer medium supply tray, it is possible to reduce the portion of the image forming apparatus that protrudes in the horizontal direction, and to reduce the installation area. Can be achieved.

According to a sixth aspect of the present invention, there is provided a color image forming apparatus according to the fifth aspect, wherein the developing means is provided as a process cartridge. The supply tray and the process cartridge are detachably disposed from a side surface of the belt-like intermediate transfer member provided so that the surface thereof moves in a substantially vertical direction and facing the surface. Features.

According to the color image forming apparatus of the present invention, the transfer medium supply tray and the process cartridge are formed of a belt-like intermediate transfer member provided so that the surface moves substantially vertically. It can be attached and detached from the side surface on the side facing the surface. Therefore, other objects and the like can be arranged near the side portions other than the side portion, and even when the installation region of the apparatus main body is narrow, the region can be effectively used.

According to a seventh aspect of the present invention, there is provided a color image forming apparatus as set forth in any one of the first to fifth aspects, wherein the color image forming apparatus is provided so as to face the intermediate transfer member. Secondary transfer means for transferring the developer image formed on the intermediate transfer member to a transfer medium, a fixing device for fixing the developer image to the transfer medium after the transfer, and the transfer after the fixing. A double-sided printing transfer medium transporting unit for reversing the front side and the back side of the medium and transporting the transfer medium again to the secondary transfer unit, wherein the double-sided printing transfer medium transporting unit and the secondary transfer unit are , And is disposed vertically below the intermediate transfer member.

According to the color image forming apparatus of the present invention, the transfer medium after fixing is turned upside down by the transfer medium transfer means for double-sided printing, and is transferred again to the secondary transfer means. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

According to another aspect of the present invention, there is provided a color image forming apparatus, wherein: a belt-shaped intermediate transfer member provided so that a surface thereof moves along a substantially vertical direction; A plurality of electrostatic latent image carriers arranged side by side in a substantially vertical direction along, a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers,
A plurality of developing means including a plurality of layer thickness regulating members provided so as to contact each of the plurality of developer carrying members,
A transfer medium supply tray for supplying a transfer medium; and a transfer medium discharge tray on which a transfer medium discharged after completion of the image forming step is placed. The transfer medium discharge tray faces the plurality of electrostatic latent image carriers of the intermediate transfer body. The surface is set so as to move from a vertical upward direction to a downward direction, and a visible image forming unit including the intermediate transfer body, the plurality of electrostatic latent image carriers, and the plurality of developing units. Is provided vertically below the transfer medium discharge tray and vertically above the transfer medium supply tray.

According to the color image forming apparatus of the present invention, the surface of the intermediate transfer member facing the plurality of electrostatic latent image carriers moves from the upper side in the vertical direction to the lower side. The visible image forming means including the intermediate transfer body and the plurality of electrostatic latent image carriers and the plurality of developing means is vertically lower than the transfer medium discharge tray, Since it is provided vertically above the transfer medium supply tray, the distance between the opposing position of the intermediate transfer member and the secondary transfer means and the transfer medium supply tray is shortened, and the printing time is shortened. Can be. In addition, since the above-described units are arranged one above the other in the up-down direction, the protrusion from the image forming apparatus main body in the lateral direction is small, and the installation area can be reduced.

According to a ninth aspect of the present invention, there is provided a color image forming apparatus according to the eighth aspect, wherein the developing means is provided as a process cartridge. The supply tray and the process cartridge are detachably disposed from a side surface of the belt-like intermediate transfer member provided so that the surface thereof moves in a substantially vertical direction and facing the surface. Features.

According to a ninth aspect of the present invention, in the color image forming apparatus, the transfer medium supply tray and the process cartridge are formed of a belt-shaped intermediate transfer member provided so that the surface moves substantially vertically. It can be attached and detached from the side surface on the side facing the surface. Therefore, other objects and the like can be arranged near the side portions other than the side portion, and even when the installation region of the apparatus main body is narrow, the region can be effectively used. Moreover, the visible image forming means includes:
Vertically below the transfer medium discharge tray,
Since the transfer path is provided vertically above the transfer medium supply tray, the transfer path of the transfer material after transfer can be provided on the side opposite to the detachable side of the process cartridge when viewed from the intermediate transfer body, The process cartridge can be easily attached and detached without being hindered by the transfer path after the transfer of the transfer material.

[0028] The color image forming apparatus according to claim 10 is
10. The color image forming apparatus according to claim 9, wherein the developer image is arranged to face the intermediate transfer body, and transfers a developer image formed on the intermediate transfer body to a transfer medium. A secondary transfer unit, a fixing device for fixing the developer image to the transfer medium after the transfer, and reversing the front and back surfaces of the fixed transfer medium while transferring the transfer medium to the secondary transfer unit. The image forming apparatus further includes a double-sided printing transfer medium conveying unit that conveys again, and the double-sided printing transfer medium conveying unit and the secondary transfer unit are disposed vertically below the intermediate transfer body. I do.

According to the color image forming apparatus of the tenth aspect, in addition to the operation of the color image forming apparatuses of the eighth and ninth aspects, the transfer medium after fixing is transferred by the transfer medium transport means for double-sided printing. The front and back sides are reversed and 2
The sheet is conveyed again to the next transfer unit. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

The color image forming apparatus according to claim 11 is
In order to solve the above-mentioned problem, a belt-shaped intermediate transfer member provided so that a surface thereof moves in a substantially vertical direction, and a plurality of static transfer members arranged in a substantially vertical direction along a moving direction of the surface. An electrostatic latent image carrier, a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers, and a plurality of developer carriers provided to be in contact with each of the plurality of developer carriers. A plurality of developing means including a plurality of layer thickness regulating members provided so as to face the intermediate transfer body, and a secondary means for transferring a developer image formed on the intermediate transfer body to a transfer medium. A transfer unit, a fixing device for fixing the developer image to the transfer medium after the transfer, and reversing the front and back surfaces of the transfer medium after the fixing and transporting the transfer medium to the secondary transfer unit again Transfer medium transport means for double-sided printing, The surface facing the plurality of electrostatic latent image carriers is set so as to move from a vertical upward direction to a downward direction, and the double-sided printing transfer medium transport unit and the secondary transfer unit are , And is disposed vertically below the intermediate transfer member.

According to the color image forming apparatus of the present invention, the transfer medium after fixing is turned upside down by the transfer medium conveying means for double-sided printing, and is conveyed again to the secondary transfer means. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First embodiment)

First, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional side view of a color laser printer as a color image forming apparatus to which the present invention is applied.

The color image forming apparatus 1 illustrated in FIG.
A visible image forming unit 4, a belt-shaped intermediate transfer body 5,
Fixing unit 8, paper feed unit 9, paper discharge tray 10
And

The visible image forming unit 4 performs each visible image process using each of magenta (M), cyan (C), yellow (Y), and black (Bk) toners.
Developing units 51M, 51C, 51Y, 51Bk, photosensitive drums 3M, 3C, 3Y, 3Bk, cleaning roller 70
M, 70C, 70Y, 70Bk, chargers 71M, 71
C, 71Y, 71Bk, and exposure means 72M, 72C,
72Y and 72Bk are provided. Hereinafter, each of these components will be described in detail.

First, the developing units 51M, 51C, 51Y, 5
1Bk includes a developing roller 52M as a developer carrier,
52C, 52Y, and 52Bk are provided. Each of the developing rollers 52M, 52C, 52Y, and 52Bk is formed in a cylindrical shape using conductive silicone rubber as a base material, and further has a coat layer of a resin or rubber material containing fluorine on the surface. The developing rollers 52M, 52C, 52Y,
In 52Bk, the base material does not necessarily need to be formed of conductive silicone rubber, and may be formed of conductive urethane rubber. The ten-point average roughness (Rz) of the surface is 3 to 5 μm.
m, which is smaller than the average particle diameter of the toner of 9 μm. The developing roller 5
A predetermined voltage is applied to 2M, 52C, 52Y, and 52Bk, and is configured to have a predetermined potential difference between the photosensitive drums 3M, 3C, 3Y, and 3Bk.

Each developing unit 51M, 51C, 51Y, 51B
k also includes supply rollers 53M, 53C, 53Y, 5
3Bk is provided. Supply rollers 53M, 53C,
53Y and 53Bk are conductive sponge rollers,
The developing rollers 52M, 52C, 52Y, and 52Bk are arranged so as to press and contact with the sponge elastic force. The supply rollers 53M, 53C, 53Y, 5
As 3Bk, other suitable members such as conductive silicone rubber or urethane rubber can be used.

Each developing device is further provided with layer thickness regulating blades 54M, 54C, 54Y, 54Bk as layer thickness regulating members.
Is provided. Layer thickness regulating blade 54M,
54C, 54Y, and 54Bk are formed of stainless steel or the like, and the base ends thereof are the developing device cases 55M, 55C, 55Y, and 55B.
Support portions 54aM, 54aC, 54a fixed to Bk
Y, 54aBk and supporting portions 54aM, 54aC, 5
The contact portions 54bM, 54bC provided at the distal end extending above the base ends of the 4aY and 54aBk and made of conductive silicone rubber or conductive fluorine-containing rubber or resin.
54bY and 54bBk. Contact part 54b
M, 54bC, 54bY, 54bBk are the supporting portions 54a
Due to the elastic forces of M, 54aC, 54aY, and 54aBk, they are pressed against the developing rollers 52M, 52C, 52Y, and 52Bk from below the developing rollers 52M, 52C, 52Y, and 52Bk. Contact portions 54bM, 54bC, 54bY,
As shown in FIG. 1, the shape of 54bBk is formed such that the cross section is a substantially half-moon-shaped convex shape. Further, in the present embodiment, the layer thickness regulating blades 54M, 54C, 54
A predetermined voltage is applied to Y and 54Bk. The contact portions 54bM, 54bC, 54bY, and 54bBk are disposed below a horizontal surface including the axial centers of the developing rollers 52M, 52C, 52Y, and 52Bk, respectively.

The developing device cases 55M, 55C, 55
The toner stored in Y, 55Bk is a positively charged non-magnetic one-component developer, and a well-known colorant such as carbon black is added to a styrene-acrylic resin formed into a spherical shape by suspension polymerization, and It has toner base particles having an average particle diameter of 9 μm to which a charge control agent such as nigrosine, triphenylmethane, or quaternary ammonium salt or a charge control resin is added. The toner T is configured by adding silica as an external additive to the surface of the toner base particles. The silica as the external additive is subjected to a well-known hydrophobic treatment using a silane coupling agent, silicone oil, or the like, has an average particle size of 10 nm, and is added in an amount of 0.6% by weight of the toner base particles. It is. Each developing device case 55M, 55
C, 55Y, and 55Bk contain magenta, cyan, yellow, and black toners, respectively.

As described above, the toner is a suspension polymerization toner having an extremely spherical shape, and 0.6% by weight of hydrophobically treated silica having an average particle diameter of 10 nm is added as an external additive. Extremely fluid. for that reason,
A sufficient charge amount can be obtained by frictional charging. Further, since there is no corner portion unlike pulverized toner, it is hard to receive a mechanical force, has excellent followability to an electric field, and has good transfer efficiency.

A photosensitive drum 3M as an electrostatic latent image carrier,
As 3C, 3Y, and 3Bk, for example, a material in which a positively chargeable photosensitive layer is formed on an aluminum base material is used. The thickness of the photosensitive layer is formed to be 18 μm or more,
The aluminum base is used as an earth layer. Further, the photosensitive drums 3M, 3C, 3Y, 3
Bk is driven to rotate in the direction of the arrow shown in FIG. In addition,
In the present embodiment, the photosensitive drums 3M, 3C, 3Y,
A speed difference is provided between 3Bk and the intermediate transfer member 5.

Cleaning rollers 70M, 70C, 70
Y and 70Bk are rollers made of an elastic body such as a conductive sponge, and are configured to rub against the photosensitive drums 3M, 3C, 3Y and 3Bk below the photosensitive drums 3M, 3C, 3Y and 3Bk. I have. This cleaning roller 70
M, 70C, 70Y, and 70Bk are configured such that a negative voltage of the opposite polarity of the toner is applied to the photosensitive drums 3M, 3C, 3Y, and 3B by a power supply (not shown).
The remaining toner is removed from the photosensitive drums 3M, 3C, 3Y, 3Bk
Is configured to be removed from. In this embodiment, since a so-called cleanerless developing method is adopted,
In a predetermined cycle after the development process is completed, the cleaning rollers 70M, 70C, 70Y, 70Bk
The residual toner removed by the photosensitive drum 3M is again
It is also possible to return to the 3C, 3Y, 3Bk side.

Charging devices 71M, 71C as charging means
71Y and 71Bk are scorotron type chargers,
The cleaning rollers 70M, 70C, 70Y, 70
Bk, the photosensitive drums 3M, 3C, 3Y, 3Bk
Downstream of the rotation direction of the photosensitive drums 3M, 3M,
C, 3Y, and 3Bk, the photosensitive drums 3M,
C, 3Y, and 3Bk are disposed so as to face each other. In addition, as the chargers 71M, 71C, 71Y, and 71Bk,
A roller type charger that contacts the photosensitive drums 3M, 3C, 3Y, and 3Bk may be used.

Exposure means 72M, 72C, 72Y, 72B
k is composed of an LED light source, and the charger 71
M, 71C, 71Y, and 71Bk, on the downstream side in the rotation direction of the photosensitive drums 3M, 3C, 3Y, and 3Bk,
The photosensitive drums 3M, 3C, 3Y, and 3Bk are disposed to face the surfaces of the photosensitive drums 3M, 3C, 3Y, and 3Bk from below. Exposure means 72M, 72C, 72Y,
With 72Bk, light corresponding to the drawing data is applied to the photosensitive drum 3
Irradiation is performed on the surfaces of M, 3C, 3Y, and 3Bk, and an electrostatic latent image for each color is formed on the surfaces of the photosensitive drums 3M, 3C, 3Y, and 3Bk.

With the above configuration, the developing roller 52
M, 52C, 52Y, 52Bk and photosensitive drums 3M, 3M
C, 3Y, and 3Bk, the photosensitive drum 3
For a positive polarity (positively charged) electrostatic latent image formed on M, 3C, 3Y, and 3Bk, a positively charged toner can be favorably developed by a reversal developing method, and an extremely high-quality image can be formed. Can be formed.

The belt-shaped intermediate transfer member 5 is formed by forming a conductive sheet such as polycarbonate or polyimide in a belt shape. As shown in FIG. 1, the belt-like intermediate transfer member 5 is stretched over two drive rollers 60 and 62, and the intermediate transfer roller 5 is located near the photosensitive drums 3M, 3C, 3Y and 3Bk. 61M, 61C, 6
1Y and 61Bk are provided. The direction of movement of the surface of the intermediate transfer body 5 on the side facing the photosensitive drums 3M, 3C, 3Y, and 3Bk is set to a direction in which the surface moves from a vertically upward direction to a downward direction, as shown in FIG.

The intermediate transfer rollers 61M, 61C, 61Y,
A predetermined voltage is applied to 61Bk, so that the toner images formed on the photosensitive drums 3M, 3C, 3Y, and 3Bk are transferred to the belt-shaped intermediate transfer member 5 made of the conductive sheet. Have been. Further, a roller 63 is provided opposite to a position where the toner image is transferred to a sheet, that is, a roller 62 in a vertically downward direction with respect to the intermediate transfer body 5. Has been applied. As a result, the four-color toner images carried on the belt-shaped intermediate transfer member 5 are transferred to the paper.

The photosensitive drums 3M, 3M
On the side opposite to the side facing C, 3Y and 3Bk, a cleaning device 6 is provided as shown in FIG. The cleaning device 6 includes a scraping member 65 and a case 66. The cleaning device 65 scrapes toner remaining on the intermediate transfer member 5 and stores the toner in the case 66.

The fixing unit 8 includes a heating roller 82 and a pressure roller 81. The fixing unit 8 heats and transports the sheet carrying the toner images of four colors while holding the sheet by the heating roller 82 and the pressure roller 81. By applying pressure, the toner image is fixed on the paper.

The paper feeding unit 9 is provided at the lowermost part of the apparatus, and includes a storage tray 91 for storing the paper P and a pickup roller 92 for feeding out the paper. The paper feeding unit 9 includes exposure units 72M, 72C, 72
Y, 72Bk, visible image unit 4, photosensitive drum 3M, 3
The sheet P is supplied at a predetermined timing with the image forming process by the C, 3Y, 3Bk and the intermediate transfer member 5. Paper P supplied from paper feed unit 9
Is transported by the transport roller pair 100 to the pressure contact portion between the intermediate transfer body 5 and the roller 63.

The paper discharge tray 10 is provided at the uppermost part of the apparatus, is provided on the paper discharge side of the fixing unit 8, is discharged from the fixing unit 8, and has a pair of conveying rollers 1.
It is configured to accommodate the paper P conveyed by 01 and 102.

In this embodiment, as shown in FIG. 1, the front cover 2 is configured to be rotatable about the shaft 20 in the direction of the arrow in FIG. By opening the front cover 2, the developing units 51M, 51C, 51Y, 51
Bk can be easily exchanged.

Next, the operation of the color image forming apparatus according to the present embodiment as described above will be described. First, the photosensitive layers of the photosensitive drums 3M, 3C, 3Y, and 3Bk are
The photosensitive layers are uniformly charged by 2M, 72C, 72Y, and 72Bk.
Exposure is performed using LED light corresponding to magenta, cyan, yellow, and black images irradiated by C, 72Y, and 72Bk. And the magenta developing device 5
1M, a cyan developing device 51C, a yellow developing device 51Y, and a black developing device 51Bk.
The electrostatic latent images formed on the C, 3Y, and 3Bk photosensitive layers
A magenta toner, a cyan toner, a yellow toner, and a black toner are adhered, and magenta, cyan, yellow, and black are developed. The magenta, cyan, yellow, and black toner images formed as described above are temporarily
Is transferred onto the surface of

Next, the photosensitive drums 3M, 3C, 3
Y, the toner remaining on 3Bk is the cleaning roller 7
OM, 70C, 70Y, 70Bk.

The toner images of the respective colors are formed with a slight time difference in accordance with the moving speed of the intermediate transfer member 5 and the positions of the photosensitive drums 3M, 3C, 3Y, 3Bk. Are transferred so as to be superimposed on the intermediate transfer member 5.

The four-color toner images formed on the intermediate transfer member 5 as described above are transferred onto the sheet P supplied from the paper feeding unit 9 at the position where the roller 63 and the intermediate transfer member 5 are pressed against each other. Is done. Then, the toner image is fixed on the paper P in the fixing unit 8 and is discharged onto the paper discharge tray 10. As described above, a four-color image is formed.

As described above, the color image forming apparatus of this embodiment employs a so-called tandem system in which the visible image units 4 for each color are arranged along the moving direction of the intermediate transfer member 5. Therefore, a color image can be formed at the same high speed as in the case of forming a single color image.

In this embodiment, since a belt-shaped intermediate transfer member 5 is used, the surface facing the developing device can be made long, and as described above, a plurality of developing devices can be Can be installed side by side.

The color image forming apparatus according to the present embodiment employs a so-called tandem system.
C, 51Y, and 51Bk employ a developing device using a non-magnetic one-component developer.
C, 51Y, and 51Bk can be reduced in size, and the overall size of the color image forming apparatus can be reduced.

In addition, the thickness regulating blades 54M, 54
C, 54Y, and 54Bk are developing rollers 52M, 52C,
Since they are provided below the centers of 52Y and 52Bk, the size of the entire color image forming apparatus can be further reduced. That is, the photosensitive drums 3M, 3M
When the moving direction of the surface on the side facing C, 3Y, 3Bk is set from the vertical upper direction to the lower direction as shown in FIG. 1, the rotation directions of the photosensitive drums 3M, 3C, 3Y, 3Bk are changed. Since it is counterclockwise, the cleaning roller 70
M, 70C, 70Y, 70Bk, chargers 71M, 71
C, 71Y, 71Bk, and exposure means 72M, 72C,
72Y and 72Bk are photosensitive drums 3M, 3C, 3Y, 3
It is necessary to provide it below Bk. Therefore, it is necessary to secure a space for accommodating these units below the photosensitive drums 3M, 3C, 3Y, and 3Bk. Therefore, the thickness regulating blades 54M, 54M,
4C, 54Y, and 54Bk, the developing device 5
In 1M, 51C, 51Y, and 51Bk, the upper part of the developing rollers 52M, 52C, 52Y, and 52Bk can be reduced in size, and as shown in FIG.
Developing roller 52 immediately below 71C, 71Y, 71Bk
M, 52C, 52Y, and the upper part of 52Bk can be arranged. As a result, the photosensitive drums 3M, 3C,
3Y, 3Bk, cleaning rollers 70M, 70C, 7
0Y, 70Bk, chargers 71M, 71C, 71Y, 71
The space occupied by the process unit including Bk, the exposure units 72M, 72C, 72Y, and 72Bk and the developing units 51M, 51C, 51Y, and 51Bk can be reduced in the vertical direction, and as a result, the overall size of the color image forming apparatus is reduced. Can be realized.

Further, the color image forming apparatus of the present embodiment includes the photosensitive drums 3M, 3C, 3Y, 3B of the intermediate transfer member 5.
The movement direction of the surface on the side opposite to k is from the upper side in the vertical direction to the lower side, and at the position below the intermediate transfer body 5, the transfer is performed on the sheet P by the roller 63. 9 can be provided at the bottom of the apparatus, and the installation area of the color image forming apparatus can be reduced. In addition, when the paper feeding unit 9 is provided at the lowermost part of the apparatus, there is an advantage that handling such as replenishment of the paper P becomes easier as compared with a case where a cassette type unit is provided at the upper part of the apparatus. Further, as shown in FIG. 1, the transport path of the sheet P to the roller 63 can be shortened, and the time until the end of printing can be shortened.

In the present embodiment, as described above, since the toner is prepared by the polymerization method, the fluidity is extremely excellent. Therefore, the thickness regulating blades 54M, 5M
4C, 54Y, and 54Bk to developing rollers 52M, 52
C, 52Y, and 52Bk, the toner scraped off by the layer thickness regulating blades 54M, 54C, 54Y, and 54Bk tends to stay without being circulated. Since a polymerized toner having excellent properties is used, such a problem does not occur, and printing defects can be reliably prevented.

Further, since the polymerized toner is excellent in fluidity, there is an advantage that the image quality is less deteriorated even when the transfer step is performed twice using the intermediate transfer member as in the present embodiment.

Further, since the transfer residual toner can be reduced by using the polymerized toner, the transfer residual toner can be surely removed even when the cleanerless developing system is used.

In particular, when the cleanerless developing system is used, no space is required for the waste toner container, and the entire color image forming apparatus can be reduced in size.

Furthermore, in the present embodiment, the cleaning rollers 70M, 70C, 70Y, and 70Bk are configured to temporarily secure toner by the action of an electric field. The cleaning rollers 70M, 70C, 70Y, and 70Bk can be returned to the photosensitive drums 3M, 3C, 3Y, and 3Bk, and even if the amount of untransferred toner increases, it can be reliably prevented from appearing in printing.

Further, the cleaning rollers 70M, 70M
C, 70Y, and 70Bk are transferred to the photosensitive drums 3M, 3C, 3
Y, 3Bk, so that toner adhered to the cleaning rollers 70M, 70C, 70Y, 70Bk does not drop onto the photosensitive drums 3M, 3C, 3Y, 3Bk due to gravity. Defects can be reliably prevented.

Further, in the present embodiment, the sheet feeding unit 9, the intermediate transfer member 5 and the photosensitive drums 3 M, 3 C, 3
Y, 3Bk and developing units 51M, 51C, 51Y, 51
Since the process unit composed of Bk and the paper discharge tray 10 can be provided in the order of the paper supply unit 9, the process unit, and the paper discharge tray 10 from the lower side in the vertical direction to the upper side, the apparatus main body is provided. The portion protruding from the space can be eliminated, and the installation area can be reduced.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment differs from the first embodiment in that a paper transport path for double-sided printing is provided as shown in FIG. 2 in addition to the normal paper transport path as shown in FIG. different. Also, the cleaning rollers 70M, 70C, 70
Cleaning means 73M, 73C, 73Y provided with a cleaning blade and a container in place of Y and 70Bk;
73Bk is also different from the first embodiment. Furthermore,
In the present embodiment, as shown in FIG.
M, 51C, 51Y, and 51Bk also differ from the first embodiment in that they are configured as process cartridges that are detachably provided to the main body. In the case of this embodiment,
By using amorphous silicon for the photosensitive drums 3M, 3C, 3Y, and 3Bk, it is possible to configure the photosensitive drums without replacement.

In the present embodiment, the developing device 51M,
51C, 51Y, and 51Bk are provided as process cartridges so as to be detachable from the main body, and transport of the sheet P from the pressure contact portion between the roller 63 as the secondary transfer unit and the intermediate transfer body 5 to the sheet discharge tray 10. The path is changed to the intermediate transfer member 5
Viewed from the side, it can be on the side opposite to the side on which the process cartridge is provided. This is because, similarly to the first embodiment, the sheet supply unit 9, the process unit, and the sheet discharge tray 10 can be stacked in this order from the lower side in the vertical direction to the upper side. Therefore, FIG.
As shown in FIG. 5, the front cover 2 is rotated in the direction of arrow A about the shaft 20 to open the inside of the apparatus, so that the paper P
The process cartridge can be easily attached / detached without being hindered by the transfer path.

Further, in the present embodiment, the paper feed tray 91 of the paper feed unit 9 is also configured to be attached and detached in the direction of arrow B from the same side as the process cartridge. In other words, since the work surface for attaching and detaching the process cartridge and the paper feed tray 91 is common, other objects and the like can be arranged on the other surface side. can do.

In the present embodiment, a pair of transport rollers 101 provided at the paper discharge portion of the fixing unit 8 and a pair of transport rollers 10 provided further downstream in the transport direction of the paper P are provided.
3, a path switching plate 104 is provided.
Between the pair of conveying rollers 103 and the pair of conveying rollers 108 provided on the upstream side in the conveying direction of the sheet P with respect to the roller 63 as the secondary transfer unit, a double-sided printing sheet conveying path 105 and a pair of conveying rollers 106 and 107 are provided.

When performing double-sided printing in this embodiment, first, the path switching plate 104 is set to the position shown in FIG. Next, the paper P discharged from the fixing unit 8 is transported halfway by the transport roller pair 103, and the paper P
The conveyance is temporarily stopped just before the rear end of the sheet is discharged from the conveyance roller pair 103. Next, the path switching plate 104 is rotated clockwise as shown in FIG. 2 to rotate the conveying roller pair 103 in the reverse direction, and the sheet P is supplied to the double-sided printing conveying path 105 by the conveying roller pairs 103, 106, and 107. Then, the sheet P is conveyed by the conveying roller pair 108 to the press-contact portion between the roller 63 and the intermediate transfer body 5, so that the sheet P
Can be printed on the back surface of the. Since double-sided printing is possible in this manner, it is possible to contribute to saving paper P.

Further, in this embodiment, such a double-sided printing mechanism and a roller 63 as a secondary transfer means are provided.
Because it is configured to be provided at the lower part of the apparatus, in a vertical type tandem type color image forming apparatus capable of high-speed printing,
It was possible to reduce the size of the entire apparatus while enabling double-sided printing.

In the above description, the developing devices 51M, 5M
1C, 51Y, and 51Bk are provided as process cartridges in a detachable manner with respect to the main body. However, the present invention is not limited to such a configuration. As shown in FIG. , 3C, 3Y, and 3Bk and the developing devices 51M, 51C, 51Y, and 51Bk may be integrally formed, and may be provided as a process cartridge so as to be detachable from the main body. In this case, the cleaning means 73M, 73C, 73Y, and 73Bk are provided below the photosensitive drums 3M, 3C, 3Y, and 3Bk. Even if are separated from each other, since the openings of the cleaning means 73M, 73C, 73Y, and 73Bk face upward, there is an advantage that toner does not spill.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment differs from the first embodiment in that a belt-like intermediate transfer member 5 is arranged slightly obliquely as shown in FIG.

As described above, even when the belt-like intermediate transfer member 5 is arranged slightly obliquely, the installation area of the apparatus can be reduced.

The present invention relates to an image forming apparatus such as a copying machine, and furthermore, the present invention relates to an image forming apparatus using a non-magnetic one-component developer other than a suspension polymerization toner, for example, an emulsion polymerization apparatus. The present invention can be similarly applied to an image forming apparatus using another polymerized toner obtained by the above method.

[0081]

As described above, according to the color image forming apparatus of the first aspect, the surface of the intermediate transfer member facing the plurality of electrostatic latent image carriers is moved from the top in the vertical direction. In addition to moving downward, the plurality of layer thickness regulating members are provided below the plurality of developer carriers in the vertical direction. The size of the part can be reduced, and as a result, the size of the entire color image forming apparatus can be reduced. Further, since the plurality of developing means are developing means using a non-magnetic one-component developer as a developer, they can be realized with a simple configuration, and the developing means itself can be reduced in size.
As a result, the size of the entire color image forming apparatus can be further reduced.

According to the color image forming apparatus of the present invention, since the developer is a polymerized toner formed by a suspension polymerization method, the layer thickness regulating member is disposed below the developer carrier as described above. Even in this case, due to the high fluidity of the polymerized toner, the toner scraped by the layer thickness regulating member can be prevented from staying without being circulated, and the occurrence of printing failure due to the staying can be reliably suppressed. .

According to the color image forming apparatus of the present invention, after the developer images formed on each of the plurality of electrostatic latent image carriers are transferred to the intermediate transfer member, each of the electrostatic latent image carriers is The developer remains on the body, and the residual developer is recovered by each of the plurality of developer carriers through charging and exposure together with the movement of each electrostatic latent image carrier. Therefore, since it is not necessary to provide a large container for collecting the transfer residual developer, the size of the image forming apparatus can be reduced. In particular, when a polymerized toner having high fluidity is used, the transfer residual toner itself can be reduced, and such a method of collecting the transfer residual developer can be easily realized.

According to the color image forming apparatus of the present invention, after the developer image is transferred to the intermediate transfer member, the developer remains on each of the electrostatic latent image carriers. The developer is temporarily held by a plurality of cleaning rollers by the action of an electric field. And the reserved developer is
It can be collected by returning to the electrostatic latent image carrier during non-image formation. Therefore, even if the amount of the transfer residual developer increases,
Appearance in printing can be reliably prevented. Further, since the plurality of cleaning rollers are provided below each of the electrostatic latent image carriers in the vertical direction, the developer attached to the cleaning rollers drops onto the electrostatic latent image carrier by weight. Therefore, printing defects due to the falling developer can be reliably prevented.

According to the color image forming apparatus of the present invention, the visible image forming means including the intermediate transfer body, the plurality of electrostatic latent image carriers, and the plurality of developing means is provided in the transfer medium discharge tray. Since it is provided vertically below the transfer medium supply tray and vertically above the transfer medium supply tray, it is possible to reduce the portion of the image forming apparatus that protrudes in the horizontal direction, and to reduce the installation area. Can be achieved.

According to the color image forming apparatus of the present invention, the transfer medium supply tray and the process cartridge are formed of a belt-shaped intermediate transfer member provided so that the surface thereof moves substantially vertically. It can be attached and detached from the side surface on the side facing the surface. Therefore, other objects and the like can be arranged near the side portions other than the side portion, and even when the installation region of the apparatus main body is narrow, the region can be effectively used.

According to the color image forming apparatus of the present invention, the transfer medium after fixing is turned upside down by the transfer medium transfer means for double-sided printing, and is transferred again to the secondary transfer means. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

According to the color image forming apparatus of the present invention, the surface of the intermediate transfer member facing the plurality of electrostatic latent image carriers moves vertically upward from below. The visible image forming means including the intermediate transfer body and the plurality of electrostatic latent image carriers and the plurality of developing means is vertically lower than the transfer medium discharge tray, Since it is provided vertically above the transfer medium supply tray, the distance between the opposing position of the intermediate transfer member and the secondary transfer means and the transfer medium supply tray is shortened, and the printing time is shortened. Can be. In addition, since the above-described units are arranged one above the other in the up-down direction, the protrusion from the image forming apparatus main body in the lateral direction is small, and the installation area can be reduced.

According to the color image forming apparatus of the ninth aspect, the transfer medium supply tray and the process cartridge are formed of a belt-shaped intermediate transfer member provided so that the surface moves substantially vertically. It can be attached and detached from the side surface on the side facing the surface. Therefore, other objects and the like can be arranged near the side portions other than the side portion, and even when the installation region of the apparatus main body is narrow, the region can be effectively used. Moreover, the visible image forming means includes:
Vertically below the transfer medium discharge tray,
Since the transfer path is provided vertically above the transfer medium supply tray, the transfer path of the transfer material after transfer can be provided on the side opposite to the detachable side of the process cartridge when viewed from the intermediate transfer body, The process cartridge can be easily attached and detached without being hindered by the transfer path after the transfer of the transfer material.

According to the color image forming apparatus of the tenth aspect, in addition to the operation of the color image forming apparatus of the eighth and ninth aspects, the transfer medium after fixing is transferred by the transfer medium transport means for double-sided printing. The front and back sides are reversed and 2
The sheet is conveyed again to the next transfer unit. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

According to the color image forming apparatus of the present invention, the transfer medium after fixing is turned upside down by the transfer medium transfer means for double-sided printing, and is transferred again to the secondary transfer means. Therefore, printing can be performed on both sides of the transfer medium, which contributes to saving of the transfer medium. Furthermore, since the transfer medium conveying means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member, the apparatus body can be downsized despite the possibility of double-sided printing. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic sectional side view of a laser beam printer according to a first embodiment of the present invention.

FIG. 2 is a schematic side sectional view of a laser beam printer according to a second embodiment of the present invention.

FIG. 3 is a view showing a state in which a front cover of the laser beam printer of FIG. 2 is opened and a process cartridge is taken out.

FIG. 4 is a view showing a state in which a front cover of the laser beam printer of FIG. 2 is opened and a process cartridge including a photosensitive drum is taken out.

FIG. 5 is a schematic sectional side view of a laser beam printer according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser beam printer 3M, 3C, 3Y, 3Bk ... Photosensitive drum 5 ... Intermediate transfer body 8 ... Fixing unit 9 ... Feeding unit 10 ... Discharge tray 63 ... Rollers 51M, 51C, 51Y, 51Bk ... Developing device (process cartridge) 52M, 52C, 52Y, 52Bk: Developing rollers 54M, 54C, 54Y, 54Bk: Layer thickness regulating blades 70M, 70C, 70Y, 70Bk: Cleaning rollers 71M, 71C, 71Y, 71Bk: Chargers 72M, 72C, 72Y, 72Bk ... Exposure unit 91... Paper feed tray 104... Path switching plate 105... Double-sided printing paper transport path 106, 107, 108.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/18 G03G 15/00 556 2H077 15/08 507 15/08 507B 21/10 21/00 312 F term (Ref.)

Claims (11)

[Claims] 1. A belt-shaped intermediate transfer member provided so that a surface thereof moves in a substantially vertical direction, and a plurality of electrostatic latent images arranged in a substantially vertical direction along a moving direction of the surface. A carrier, a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers, and a plurality of developers provided to contact each of the plurality of developer carriers. A plurality of developing means including: a layer thickness regulating member; a plurality of charging means disposed to face each of the plurality of electrostatic latent image carriers; A plurality of exposure means for exposing the respective charged areas, and a surface of the intermediate transfer member opposed to the plurality of electrostatic latent image carriers is set so as to move vertically upward from below. Wherein the plurality of developing means include a non-magnetic one-component developer The color image forming apparatus, wherein the plurality of layer thickness regulating members are provided below the plurality of developer carriers in the vertical direction. 2. The color image forming apparatus according to claim 1, wherein said developer is a polymerized toner formed by a suspension polymerization method. 3. After the developer images formed on each of the plurality of electrostatic latent image carriers are transferred to the intermediate transfer member, the developer remaining on each electrostatic latent image carrier is transferred to each electrostatic latent image carrier. 3. The color image forming apparatus according to claim 2, wherein the image forming apparatus is configured to collect each of the plurality of developer carriers through charging and exposure together with movement of the latent image carrier. 4. A plurality of cleaning rollers for temporarily holding a developer remaining on each of the electrostatic latent image carriers after the transfer of the developer image to the intermediate transfer member by using an electric field, the cleaning rollers each comprising: 4. The color image forming apparatus according to claim 3, wherein the color image forming apparatus is provided below each of the electro-latent image carriers in the vertical direction. 5. A transfer medium supply tray for supplying a transfer medium, and a transfer medium discharge tray on which a transfer medium discharged after completion of the image forming step is placed, wherein the intermediate transfer member and the plurality of electrostatic latent images are provided. The image carrier and the visible image forming means including the plurality of developing means are provided vertically below the transfer medium discharge tray and vertically above the transfer medium supply tray. The color image forming apparatus according to any one of claims 1 to 4, wherein 6. The transfer means is provided as a process cartridge, and the transfer medium supply tray and the process cartridge are provided in a belt-like intermediate transfer form such that the surface thereof is moved substantially in a vertical direction. 6. A color image forming apparatus according to claim 5, wherein said color image forming apparatus is detachably provided from a side surface of said body facing said surface. 7. A secondary transfer means disposed to face the intermediate transfer member and transferring a developer image formed on the intermediate transfer member to a transfer medium, and a transfer device for transferring the developer image after the transfer. The image forming apparatus further comprises a fixing device for fixing the transfer medium, and a transfer medium conveying means for double-sided printing for reversing the front and back surfaces of the fixed transfer medium and conveying the transfer medium to the secondary transfer means again. 6. The color image according to claim 1, wherein the transfer medium transporting means for double-sided printing and the secondary transfer means are disposed vertically below the intermediate transfer member. Forming equipment. 8. A belt-shaped intermediate transfer member provided so that a surface thereof moves in a substantially vertical direction, and a plurality of electrostatic latent images arranged in a substantially vertical direction along a moving direction of the surface. A carrier, a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers, and a plurality of developers provided to contact each of the plurality of developer carriers. A plurality of developing means including a layer thickness regulating member, a transfer medium supply tray for supplying a transfer medium, and a transfer medium discharge tray on which a transfer medium discharged after completion of the image forming step is placed. The surface of the transfer member facing the plurality of electrostatic latent image carriers is set so as to move downward from a vertical upward direction, and the intermediate transfer member and the plurality of electrostatic latent images Visible image formation including carrier and the plurality of developing means The color image forming apparatus is characterized in that the means is provided vertically below the transfer medium discharge tray and vertically above the transfer medium supply tray. 9. The intermediate transfer device according to claim 9, wherein the developing unit is provided as a process cartridge, and the transfer medium supply tray and the process cartridge are provided in such a manner that a surface thereof moves in a substantially vertical direction. 9. The color image forming apparatus according to claim 8, wherein said color image forming apparatus is detachably provided from a side surface of said body facing said surface. 10. A secondary transfer means disposed to face the intermediate transfer member and transferring a developer image formed on the intermediate transfer member to a transfer medium, and a transfer device for transferring the developer image after the transfer. The image forming apparatus further comprises a fixing device for fixing the transfer medium, and a transfer medium conveying means for double-sided printing for reversing the front and back surfaces of the fixed transfer medium and conveying the transfer medium to the secondary transfer means again. 10. The color image forming apparatus according to claim 9, wherein the double-sided printing transfer medium conveying means and the secondary transfer means are disposed vertically below the intermediate transfer body. 11. A belt-shaped intermediate transfer member provided so that a surface thereof moves in a substantially vertical direction, and a plurality of electrostatic latent images arranged in a substantially vertical direction along a moving direction of the surface. A carrier, a plurality of developer carriers arranged to face each of the plurality of electrostatic latent image carriers, and a plurality of developers provided to contact each of the plurality of developer carriers. A plurality of developing means including a layer thickness regulating member, and a secondary transfer means disposed to face the intermediate transfer body and transferring a developer image formed on the intermediate transfer body to a transfer medium. A fixing device for fixing the developer image to the transfer medium after the transfer, and a double-sided printing for reversing the front and back surfaces of the transfer medium after the fixing and conveying the transfer medium again to the secondary transfer means. Transfer medium transport means for the intermediate transfer body. The surface facing the number of electrostatic latent image carriers is set so as to move from the upper side in the vertical direction to the lower side, and the double-sided printing transfer medium transport unit and the secondary transfer unit are A color image forming apparatus, which is disposed vertically below the intermediate transfer member.