JP2004029606A - Full-color electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic device which is small-sized and lightweight and has high reliability and high picture quality. <P>SOLUTION: Of the full-color electrophotographic device, a structure frame internally supporting respective printing devices whose positioning support precision is important has side wall parts, having mutually parallel surface parts crossing center axes of rotation of the respective printing devices, and at least two or more connection parts, connecting the side wall parts to each other, arranged in the vertical direction of the electrophotographic device across the respective printing devices; and the side wall parts and connection parts are nearly in a box shape, the structure frame is molded out of a resin in one body, and either of an image forming device and an intermediate transfer device incorporated in the structure frame has a belt extended between a plurality of rollers. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a full-color electrophotographic apparatus such as a printer and a copying machine, and more particularly to a small-sized and lightweight full-color electrophotographic apparatus having high frame support accuracy.
[0002]
[Prior art]
In a conventional electrophotographic apparatus, a structural frame is configured by combining a plurality of parts made of steel plates, and a photoconductor, a developing device, an intermediate transfer body, a fixing device, and the like are directly connected to the structural frame or via a highly rigid holding member. And supported the positioning. When a resin is used for the structural frame in the prior art, as shown in FIG. 4, parallel side walls 1L and 1R orthogonal to the rotation center axis of each printing apparatus, and one side connecting the side walls 1L and 1R to each other. Only the connecting portions 1b of the portions are integrated with resin, and a large number of highly rigid reinforcing members 18 such as steel plates are used to connect the side walls 1L and 1R to prevent distortion.
[0003]
Japanese Patent Application Laid-Open No. 9-222760 discloses a conventional technique in which a structural frame is made of resin using a single-color printer.
[0004]
[Problems to be solved by the invention]
In the electrophotographic apparatus of the related art, since the structural frame is formed of a steel plate, a large number of steel plates are screwed or welded to increase the number of components, increase the weight, and require time and labor for assembly. In addition, since the number of components is large, the dimensional error increases depending on the combination. Therefore, in order to perform accurate positioning and holding, high accuracy is required for each component.
[0005]
Since the rigidity of the resin in the conventional frame is lower than that of the steel plate, in a full-color machine for forming a multicolor image, a plurality of developing devices, image forming devices, and intermediate transfer devices in which toners of different colors are filled are used. Since the apparatus and the like must be built in the structural frame, a large space is required in the structural frame, and it is extremely difficult to secure rigidity, and it has been impossible.
[0006]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a small, lightweight, highly reliable, high-quality, full-color electrophotographic apparatus having a structural frame made of resin.
[0007]
[Means for Solving the Problems]
The full-color electrophotographic apparatus according to the present invention is characterized in that a structural frame that incorporates and supports each printing apparatus whose positioning and supporting accuracy is important has side walls having mutually parallel planar portions orthogonal to the rotation center axis of each printing apparatus. And at least two or more connecting portions for connecting the side wall portions to each other, are disposed in the up and down direction of the electrophotographic apparatus with each printing device interposed therebetween, and the side wall portions and the connecting portions have a substantially box shape, The structural claims were integrally molded of resin.
[0008]
In the full-color electrophotographic apparatus according to the present invention, either the image forming apparatus or the intermediate transfer device built in the structural frame has a belt stretched over a plurality of rollers.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 3 is a main cross-sectional view of the full-color electrophotographic apparatus 17 according to the present embodiment, and shows the arrangement of each apparatus inside the structural frame 1. The image forming apparatus 3, which is a belt-shaped photosensitive member, is elongated in the vertical direction. On the left side of FIG. 3 with respect to the image forming device 3, developing devices 4K, 4Y, 4M, and 4C in which toners, which are fine colored powders of four different colors of black, yellow, magenta, and cyan, are sealed. The intermediate transfer device 5, a transfer device 6, a recording medium supply device 7, a fixing device 8, and a recording medium discharge device 9 are arranged in an overlapping manner, and have a belt wound around a drum on the right side of FIG. And are arranged. Further, an exposure unit 10 for forming an electrostatic latent image on the image forming apparatus 3 is provided below the developing device 4C, and a recording medium holding unit 11 for storing a recording medium is further provided below the exposure unit 10. ing. Around the intermediate transfer device 5, a recording medium peeling unit 12 and an intermediate transfer device cleaning unit 13 are provided. Around the image forming device 3, a charger 14, an image forming device cleaning unit 15, , An afterimage elimination means 16 are provided.
[0011]
The operation of the full-color electrophotographic apparatus 17 shown in FIG. 3 will be described. First, the image forming apparatus 3, which is a belt-shaped photoconductor, travels in the direction of arrow P by a power source (not shown), and the charger 14 uniformly charges the surface. Next, image and character information by a personal computer, an image scanner or the like is exposed in dot units by the exposure means 10 to form an electrostatic latent image on the surface. After that, the electrostatic latent image on the image forming device 3 is developed by the developing devices 4K, 4Y, 4M,
4C, the toner is supplied and developed, visualized as a toner image, and transported to the first transfer position T1. At the first transfer position T1, a toner image is transferred from the image forming apparatus 3 to the surface of the intermediate transfer apparatus 5 due to a potential difference between the image forming apparatus 3 and the intermediate transfer apparatus 5. After passing through the first transfer position T1, the surface of the image forming apparatus 3 drops the potential to a certain value or less by irradiating the residual image erasing means 16 to erase the electrostatic latent image, and the image forming apparatus cleaning means 15 removes the latent image. The toner remaining without being transferred at one transfer position is removed, and a state in which the next toner image can be formed is obtained.
[0012]
The above operation is defined as one cycle, and the developing device 4K, 4Y, 4M, and 4C is sequentially performed in synchronization with the time required for one rotation of the intermediate transfer device 5, so that the monochromatic toner image is superimposed on the surface of the intermediate transfer device 5. A combined full-color toner image is formed.
[0013]
Here, a recording medium such as a sheet or an OHP sheet is conveyed to the second transfer position T2 by a recording medium supply device 7 as appropriate, and a monochromatic or multicolor toner image formed on the surface of the intermediate transfer device is recorded by the transfer device 6. It is transferred onto a medium. Thereafter, the recording medium is peeled off from the intermediate transfer device 5 by the recording medium peeling means 12, the toner is fixed on the recording medium by the fixing device 8, and is transported out of the full-color electrophotographic apparatus 17 by the recording medium discharge device 9. On the other hand, after the transfer of the toner image to the recording medium is completed, the remaining toner remaining on the surface of the intermediate transfer device 5 without being transferred to the recording medium is removed by the intermediate transfer device cleaning unit 13 and the next toner image is superimposed. Becomes possible.
[0014]
In the full-color electrophotographic apparatus 17 according to the present embodiment, since the image forming apparatus 3 is a belt-shaped photoconductor, a plurality of developing apparatuses 4K, 4Y, 4M, and 4C can be arranged in a stacked manner, and a recording medium can be provided. , The main body of the full-color electrophotographic apparatus 17 is small and lightweight. Further, in the full-color electrophotographic apparatus 17 of this embodiment, the running direction P of the image forming apparatus 3, the rotation direction Q of the toner carrier of the developing devices 4K, 4Y, 4M, and 4C, and the rotation direction S of the intermediate transfer device are the same. Since the transfer is in the forward direction during transfer, there is no synchronization shift during development and transfer, and therefore, there is little shift in image deformation and color overlay, resulting in high print quality.
[0015]
In the full-color electrophotographic apparatus 17 of this embodiment, the feeding direction of the recording medium 2 matches the front-back direction of the full-color electrophotographic apparatus 17, and the recording medium holding means 11 is pulled out in the front direction F of the apparatus to replenish the recording medium. Further, the front door FD pivots about the fulcrum FP, the top door TD pivots about the fulcrum TP, and the rear door RD pivots about the fulcrum RP. Therefore, in the full-color electrophotographic apparatus 17 of the present embodiment, the empty developing apparatuses 4Y, 4M, 4C, and 4K that have used up the toner are cleaned from the front side F of the apparatus, and the image forming apparatus 3 and the intermediate transfer apparatus that are regular replacement parts are cleaned. The unit 13 and the fixing device 8 are pulled out from the device upper direction T, and the intermediate transfer device 5 which is not a regular replacement component but is important for maintaining image quality is pulled out from the device rear direction R in consideration of a failure and replaced. Can be. In addition, when the recording medium is clogged, the usability is good because it is only necessary to open the opening / closing door RD on the rear surface and remove the clogged recording medium.
[0016]
Since the full-color electrophotographic apparatus 17 of the present embodiment does not have the opening and closing doors on the left and right side surfaces, other things are arranged adjacent to the left and right, and the electrophotographic apparatus is arranged along the corner of a wall of an office or the like. The electrophotographic apparatus 17 can be installed or placed in a small space on a desk, so that not only the size of the electrophotographic apparatus 17 can be reduced but also the degree of freedom of the installation place is high.
[0017]
In the electrophotographic apparatus 17 of the present embodiment, the structural frame 1 disposed therein is an integrally molded product made of resin. Specifically, in the full-color electrophotographic apparatus 17 of the present embodiment, the corresponding paper size is A4 size, the mounting weight is about 25 kg, and the structural frame is a modified PPE (polyphenylene ether and polystyrene containing 35% by weight of glass fiber as an inorganic material filler). And the distance between the opposing surfaces of the left and right side walls of the full-color electrophotographic apparatus 17 was set to 310 mm.
[0018]
In the full-color electrophotographic apparatus 17 of this embodiment, since the image forming apparatus 3 is a belt-shaped photoreceptor and a belt is also used for the intermediate transfer apparatus 5, the positioning support of the image forming apparatus 3 and the intermediate transfer apparatus 5 is high. Accuracy is required. In general, a belt-shaped device in an electrophotographic apparatus generates a speed variation due to a deviation or a slip unless it is positioned and supported with high accuracy, and as a result, an image defect such as deformation of an image occurs. Since the full-color electrophotographic apparatus 17 of this embodiment superimposes a multicolor toner image on the intermediate transfer device 5 to obtain a full-color image, a plurality of rollers which bridge the belt-shaped photoconductor as the image forming apparatus 3 are used. And the rotation center axis of the intermediate transfer device 5 require a high degree of parallelism with high accuracy. Therefore, if the structural frame 1 is deformed and the left and right side walls are slightly distorted, the above-described inter-axis parallelism becomes inaccurate, A shift occurs in the superposition of colors, which causes a defect in an image.
[0019]
Further, in order to improve the usability, the full-color electrophotographic apparatus 17 of this embodiment is provided with opening and closing doors FD, TD, and RD on the front, top, and back, respectively, and each of the printings built in the structural frame 1 is provided. The device can be attached and detached and a paper jam can be removed. Thus, a large opening is formed in the structural frame 1. In the full-color electrophotographic apparatus 17 of the present embodiment, the rigidity of the structural frame 1 was secured as described below.
[0020]
FIG. 1 shows an arrangement of a structural frame 1, an image forming device 3, developing devices 4Y, 4M, 4C, 4K, and an intermediate transfer device 5 of the full-color electrophotographic apparatus of the present embodiment. In FIG. 1, the mounting / removing direction of the image forming apparatus 3 is the apparatus upper direction T, and the developing apparatuses 4Y, 4M, 4C,
The attachment / detachment direction of 4K is the front direction F of the apparatus, and the attachment / detachment direction of the intermediate transfer apparatus 5 is the rear direction R of the apparatus. As shown in FIG. 1, the structural frame 1 has right and left side walls 1L and 1R having planar portions parallel to each other for positioning and supporting each printing apparatus, and are disposed orthogonal to the rotation center axis of each printing apparatus. Further, it has three connecting portions of a base connecting portion 1b for connecting the left and right side wall portions 1L and 1R to each other, an upper connecting portion 1t, and a rear connecting portion 1r. As described above, the structural frame 1 prints the image forming device 3, the developing devices 4Y, 4M, 4C, 4K, and the intermediate transfer device 5 that require high-precision positioning support in order to obtain good image quality. The side walls 1L, 1R and the connecting parts 1b, 1t, 1r are formed in a box-like shape having an open structure outward from the electrophotographic apparatus 17, and are combined. It was integrally molded with resin in shape.
[0021]
FIG. 2 is an exploded explanatory view in which the structural frame 1, which is originally integral, is divided into components, and the side walls 1L, 1R and the connecting portions 1b, 1t, 1r are formed.
[0022]
In the present embodiment, by using the above-described structural frame 1, each printing apparatus in which positioning and holding accuracy is important, while providing three large openings at the front, upper, and rear portions to improve usability. Around the side wall 1L having a box shape,
Since a closed space formed by the combination of 1R and the connecting portions 1b, 1t, 1r is formed, the structure frame 1 is strong. In this embodiment, since the side walls 1L, 1R and the connecting portions 1b, 1t, 1r are integrally formed of resin, the fastening does not shift due to an external force unlike a case where a steel plate is fastened by screws. It is also lightweight. Although the reference frame thickness of the integrally formed structural frame 1 of the resin of the present embodiment is 2.8 mm, the bending and torsional rigidity is the same as that of the structural frame formed using the steel plate, but the weight is 1/100. The weight was reduced to 2.3 kg, which is 5 or less. In addition, a molding machine for producing the present structural frame 1 is sufficient to have a class of 1300t class or less, and the mold may have a simple structure of simply using a slide core divided into four sides in addition to a normal core and a mold. Accuracy is also easy to obtain. As a result, the molding cycle could be shortened. In addition, since the resin is integrally molded, a complicated shape can be integrally formed, so that the assembly is easy, the number of parts can be greatly reduced, and the number of manufacturing steps of the full-color electrophotographic apparatus 17 itself is also large. Was reduced to
[0023]
Further, in the structural frame 1 of the present embodiment, the connecting portions 1b, 1t,
Reinforcing ribs Rb formed in a lattice shape continuously in a diagonal direction were formed inside 1r. The reinforcing ribs Rb increase the torsional rigidity of the structural frame 1 as a whole. That is, as described above, in the full-color electrophotographic apparatus 17 of the present embodiment, the plurality of rollers that bridge the belt-shaped photoreceptor that is the image forming apparatus 3 and the rotation center axis of the intermediate transfer apparatus 5 have high parallelism. Need. Therefore, if the parallelism between the axes of the left and right side walls 1R and 1L is inaccurate, misregistration occurs in color superposition and image defects occur. Therefore, as a result of examination by the connecting portion 1b in order to prevent a change in the degree of parallelism between the axes of the side walls 1R, 1L due to the torsional deformation of the connecting portions 1b, 1t, 1r, when the ribs are formed at diagonal directions at intervals of 25 mm. When the total cross-sectional areas of the ribs were approximately equal, the torsional rigidity was 2.6 times higher than that of a normal cross rib, and 1.8 times higher than that of a honeycomb (honeycomb) -shaped rib.
[0024]
Since the mounting weight of the full-color electrophotographic apparatus 17 of this embodiment is as light as 25 kg, the difference in weight between the full state and the empty state of the toner and paper is about 2.5 kg, which is about 10% of the total weight. Become. As described above, the position of the center of gravity fluctuates greatly depending on the use state, and the balance of the reaction force applied to the foot from the installation surface is likely to be lost. However, diagonal ribs are formed inside all of the connecting portions 1b, 1t, and 1r. As a result, the above-described deviation in the degree of parallelism between the axes due to the change in the position of the center of gravity could be suppressed to only 0.02 mm 2. Further, even when a concentrated load of 10 kg was applied to the end of the structural frame assuming an external force, the deviation of the parallelism between the shafts could be suppressed to within 0.1 mm. Therefore, it can be said that the ribs in the diagonal direction have an optimal shape for the structural frame 1 of the full-color electrophotographic apparatus 17 in which torsional rigidity is particularly important. It is not always necessary to form the ribs exactly in the diagonal direction of the connecting portion, and the ribs may be slightly shifted if difficult due to design restrictions. However, the rib height is at least 3 mm, preferably at least. The distance between the ribs is desirably 15 to 40 mm and the thickness is 1 to 2.5 mm in consideration of the reduction of the material used and the mold release during molding.
[0025]
The structural frame 1 of the full-color electrophotographic apparatus 17 of this embodiment has a side wall 1L,
1R and the ends of the planar portions of the connecting portions 1b, 1t, 1r, that is, the ends of the vertical ribs on the outer periphery of the box shape are respectively in contact with substantially the same virtual plane. In FIG. 1, since the fixing device 8 is housed inside the box-shaped inner space of the connecting portion 1r, the end of the connecting portion 1r protrudes by about 50 mm. The protrusion of the end is preferably 75 mm or less at the maximum. The reason for this is that in order to secure the parallelism between the axes due to the torsional deformation described above, the longitudinal ribs on the outer periphery of each box shape are arranged in the vicinity, so that the stress generated in the structural frame 1 due to external force or the like can be effectively reduced. This is to reduce distortion by transmitting and dispersing the external force as much as possible.
[0026]
In the structural frame 1 of this embodiment, the distance between the side walls 1L and 1R for positioning and supporting each printing apparatus is preferably 220 mm to 350 mm, which is close to the width of A4 size paper, and more than that. , It becomes difficult to secure torsional rigidity. If the reference plate thickness of the resin is increased, the facing distance between the side walls 1L and 1R can be made 350 mm or more, but there are problems such as an increase in the weight of the structural frame 1 and poor moldability. Therefore, when the facing distance between the side walls 1L and 1R is set to 350 mm or more, a reinforcing member made of a steel plate may be further provided as needed adjacent to the connecting portion. In this way, a full-color electrophotographic apparatus compatible with a print medium larger than A4 size can be realized.
[0027]
As described above, although the full-color electrophotographic apparatus of the present invention is small and lightweight, it can prevent the structural frame from being distorted due to external force or its own weight when installed on a general desk or floor. In addition, it is possible to prevent image defects such as image deformation and to perform precise color matching without deteriorating the positioning and supporting accuracy of each printing device provided inside the electrophotographic apparatus.
[0028]
In the present invention, as described above, if a high-precision positioning support is not performed, a speed variation occurs due to deviation, slippage, or the like, resulting in an image defect. This is particularly effective when used in an apparatus.
[0029]
【The invention's effect】
According to the present invention, it is possible to provide a full-color electrophotographic apparatus which is small and lightweight, and which can obtain high reliability and high image quality.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a structural frame of a full-color printer according to an embodiment and an arrangement of respective devices.
FIG. 2 is an explanatory view in which a structural frame of the embodiment is disassembled into constituent elements.
FIG. 3 is an explanatory cross-sectional view of the full-color electrophotographic apparatus of the embodiment.
FIG. 4 is a perspective view of a structural frame of a conventional electrophotographic apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Structural frame, 1L, 1R ... Side wall part, 1b, 1t, 1r ... Connection part, 2 ... Recording medium, 3 ... Image forming apparatus, 4Y, 4M, 4C, 4K ... Developing apparatus, 5 ... Intermediate transfer apparatus, 6 ... Transfer device, 7 ... Recording medium supply device, 8 ... Fixing device, 9 ... Recording medium discharge device, 10 ... Exposure means, 11 ... Recording medium holding means, 12 ... Recording medium peeling means, 13 ... Intermediate transfer device cleaning means, 14: charger, 15: image forming apparatus cleaning means, 16: residual image erasing means, 17: full color electrophotographic apparatus, 18: reinforcing member, Rb: reinforcing rib, F: front side of the apparatus, R: rear side of the apparatus, T .., Apparatus upper direction, FD, RD, TD... Opening and closing door, P... Image forming apparatus running direction, Q... Toner carrier rotation direction of developing device, S... Intermediate transfer apparatus rotating direction, T1. Second transfer position.

Claims (10)

An image forming apparatus that holds and conveys the electrostatic latent image, an exposure unit that forms an electrostatic latent image on the image forming apparatus, and a toner that is a finely colored powder supplied to the image forming apparatus, A plurality of developing devices in which toners of respective colors of black, yellow, magenta, and cyan for visualizing a latent image to form a toner image, and a toner image formed on the image forming device adjacent to the image forming device An intermediate transfer device that forms a multicolor image by sequentially superimposing the multicolor image on the surface, a transfer device that conveys the recording medium, and transfers the multicolor image formed on the intermediate transfer device onto the recording medium, and a transfer device that transfers the multicolor image onto the recording medium In a full-color electrophotographic apparatus including a fixing device that fixes the multicolored image on a recording medium, a driving device, a power supply, and a control device that controls an image forming operation,
The electrophotographic apparatus includes a structural frame containing the image forming apparatus, the intermediate transfer device, an exposure unit, and a plurality of developing devices,
The structural frame includes an opposing side wall portion and a plurality of connecting portions connecting the side wall portions,
The opposed side wall portion includes a plane portion parallel to the rotation center axis of the image forming apparatus and the intermediate transfer device, and the side wall portion and the connecting portion form a box shape. A full-color electrophotographic apparatus characterized by being integrally formed of resin. 2. The full-color electrophotographic apparatus according to claim 1, wherein one of the image forming apparatus and the intermediate transfer device extends a belt over a plurality of rollers. 3. The full-color electrophotographic apparatus according to claim 2, wherein the structural frame includes three or more openings for attaching and detaching the image forming apparatus, the intermediate transfer device, and the plurality of developing devices. Full color electrophotographic equipment. 3. The full-color electrophotographic apparatus according to claim 2, wherein a vertical rib is arranged on an outer peripheral portion of a side wall of the structural frame, and a maximum protrusion of the side wall of the structural frame is 75 mm or less from the vertical rib. Characterized full-color electrophotographic device. 2. The full-color electrophotographic apparatus according to claim 1, wherein the connecting portion of the structural frame has a box shape, and includes a continuous reinforcing rib inside the box, and the reinforcing rib is substantially on a diagonal of the box shape. A full-color electrophotographic apparatus characterized by being arranged in parallel. 6. The full-color electrophotographic apparatus according to claim 5, wherein the reinforcing ribs are formed in a lattice shape arranged in parallel with the diagonal line, and an interval between adjacent reinforcing ribs arranged in parallel is 15 mm to 40 mm, and a height is 3 mm to 3 mm. A full-color electrophotographic apparatus characterized in that the thickness is 30 mm and the thickness is 1 mm to 2.5 mm. 3. The full-color electrophotographic apparatus according to claim 2, wherein an interval between the side walls is 220 mm to 350 mm. 4. The full-color electrophotographic apparatus according to claim 3, wherein a reinforcing member formed of a steel plate connecting the side wall portions to each other is disposed adjacent to the connecting portion. An image forming apparatus that holds and conveys an electrostatic latent image; an exposure unit that forms an electrostatic latent image on the image forming apparatus; and a black, yellow, magenta, and cyan image forming unit that forms a toner image on the image forming apparatus. Four developing devices in which toners of respective colors are respectively sealed, an intermediate transfer device that forms a multicolor image by sequentially superimposing toner images formed on the image forming device adjacent to the image forming device on the surface, A transfer device that conveys the recording medium and transfers the multicolor image formed on the recording medium to the intermediate transfer device; and a fixing device that fixes the multicolor image transferred on the recording medium onto the recording medium. In a full-color electrophotographic apparatus, the electrophotographic apparatus includes a structural frame including the image forming apparatus, an intermediate transfer device, an exposure unit, and four developing devices.
The structural frame includes an opposing side wall portion and a plurality of connecting portions connecting the side wall portions,
The opposed side wall portion includes a plane portion parallel to the rotation center axis of the image forming apparatus and the intermediate transfer device, and the side wall portion and the connecting portion form a box shape. A full-color electrophotographic apparatus characterized by being integrally molded of a synthetic resin containing an inorganic filler. An image forming apparatus that holds and conveys the electrostatic latent image, an exposure unit that forms the electrostatic latent image on the image forming apparatus, and a toner of a different color that forms a color toner image on the image forming apparatus. A plurality of developing devices, an intermediate transfer device that forms a multicolor image by sequentially superimposing a toner image formed on the image forming device adjacent to the image forming device on the surface, and transporting a recording medium, and recording. In a full-color electrophotographic apparatus including a transfer device that transfers a multicolor image formed on an intermediate transfer device onto a medium and a fixing device that fixes the multicolor image transferred on the recording medium onto the recording medium,
The electrophotographic apparatus includes a structural frame integrally formed of a synthetic resin containing an inorganic material filler containing the image forming apparatus, an intermediate transfer device, an exposure unit, and a plurality of developing devices. ,
The structural frame includes an opposing side wall portion and a plurality of connecting portions connecting the side wall portions,
The opposed side wall portion includes a plane portion parallel to each other and orthogonal to a rotation center axis of the image forming apparatus and the intermediate transfer device, and the side wall portion and the connection portion form a box shape. The structural frame has an opening at a front portion, a back portion, and an upper portion of the full-color electrophotographic apparatus. A plurality of developing devices are attached and detached from the opening at the front portion, and an intermediate portion is formed from the opening at the back portion. A full-color electrophotographic apparatus, wherein a transfer device is attached and detached, and an image forming apparatus is attached and detached from an opening in an upper surface portion.

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