JP2004287462A - Color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve workability in jam removal, the replacement of a process cartridge and the maintenance care of a developing device or the like. <P>SOLUTION: By opening a front frame 8, a paper transport path is uncovered, thereby enabling the removal of a jam. An intermediate frame 40 holding the process cartridge 31 is rotatable around a support shaft 9B. To replace the process cartridge, the front frame 8 is opened, the intermediate frame 40 is turned to a position shown in figure, and the process cartridge 31 is detached. In the case of performing the maintenance care of the developing device 6 or the like, the intermediate frame 4 is opened to such an extent that it reaches the front frame 8, whereby widely uncovering the inside of the apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color image forming apparatus having an intermediate transfer member, such as a color copying machine, a color printer, and a color facsimile.

JP-A-2-294673

  Typical examples of conventional color image forming apparatuses include a type using a photosensitive drum for forming a latent image and a transfer drum for holding a transfer sheet and transferring a toner image on a photosensitive body, and a photosensitive drum. A system in which a plurality of toners are superposed on each other and transferred to transfer paper has been put to practical use. In the method using a transfer drum, the transfer paper must be electrostatically or mechanically held on the transfer drum, so it is difficult to use small-size paper such as postcards or thick paper as the transfer paper. Is not so-called paper-free. Further, in the method of mechanically holding the leading edge of the transfer paper, an image cannot be transferred to the entire surface of the transfer paper.

  A method of superposing a plurality of toner images on a photosensitive drum has also been proposed and put into practical use. In this method, a latent image is formed by charging and exposing the photosensitive member again from the previously transferred toner image. Since the development process is performed a plurality of times, it is difficult to maintain good uniformity of charging, and the image quality is inferior to that of the conventional transfer drum system.

  In order to solve these conventional drawbacks, a system that can achieve high-quality images while achieving paper-free properties so that postcards and thick paper can also be used as transfer paper has been developed. A method has been proposed in which a full-color image is obtained by sequentially superimposing and transferring the images at the same position on an intermediate transfer member such as an endless belt, and transferring and transferring this transferred image to transfer paper. However, there is a problem in the size of the machine, the jam clearance operation, and the like, in that the intermediate transfer belt is disposed in the apparatus main body while making use of the paper-free property. In order to efficiently reduce the cross-sectional area of the apparatus main body, it is necessary to reduce the volume of the circumferentially-long intermediate transfer belt body that temporarily holds the entire print image area as much as possible. Further, in order to make the structure of the intermediate transfer belt body as simple as possible and to reduce the cost, a structure in which the intermediate transfer belt member is supported by two rollers is most preferable, but on the contrary, it becomes longer in the roller axis direction (for example, In an apparatus that can use A3 size paper as transfer paper, the size becomes as large as about 260 mm.) Further, if the intermediate transfer belt is arranged in the vertical direction, the apparatus main body becomes high, and if the intermediate transfer belt is laid horizontally, the depth becomes large and the transfer paper transport path becomes long.

  In order to solve these problems, the apparatus described in Patent Document 1 uses an intermediate transfer belt to reduce the size of the transfer paper transport path by using an upward transport type. Since the paper stack and the paper discharge stack protrude, the overall size of the apparatus cannot be necessarily reduced in size.

  In view of the above-mentioned conventional problems, the present invention provides a color image forming apparatus which reduces the size of the apparatus main body by improving the arrangement of the intermediate transfer belt, improves operability of transfer paper processing, and maintains high image quality. The purpose is to provide.

  In the color image forming apparatus according to the present invention, the toner image formed on the image carrier is reduced in order to reduce the size of the apparatus body by optimally disposing the intermediate transfer belt in the color image forming apparatus. A color image that is repeatedly transferred to an intermediate transfer member, a composite toner image is formed by superimposing a plurality of toner images on the intermediate transfer member, and the synthetic toner image is collectively transferred onto the transfer paper from the intermediate transfer member and fixed. In the forming apparatus, one belt surface of a belt-like intermediate transfer member provided with at least two rollers is inclined and disposed, and the image is transferred below the inclined belt surface so as to transfer the toner image of the image carrier. A carrier is disposed, a paper feed unit is disposed below the apparatus main body, a paper discharge unit is disposed above the apparatus main body, and a transfer paper transport path extending in a direction from the paper supply unit to the paper discharge unit is provided. Features.

  A developing device for visualizing an electrostatic latent image formed on the image carrier in order to prevent the developing toner from scattering on the image carrier and preventing color mixing. The developing device and the image carrier are arranged with the contact position of the developing roller at the developing position on the image carrier being vertical or slightly inclined so that the contact position of the developing roller is on the lower side. .

  According to a third aspect of the present invention, in the color image forming apparatus, in order to further shorten the transfer paper transport path, a part of the transfer paper transport path is formed substantially parallel to the inclined belt surface of the intermediate transfer body. And

  5. A color image forming apparatus according to claim 4, wherein a writing unit for forming an electrostatic latent image on said image carrier is provided at a lower portion of the apparatus main body for stabilizing image quality of writing by said electrostatic latent image writing unit. Is provided.

  The color image forming apparatus according to the fifth aspect is characterized in that the image carrier has a belt member laid by at least two roller members in order to cope with the arrangement of a plurality of developing units.

  The color image forming apparatus according to claim 6, wherein in order to prevent transfer blur due to contact of a transfer roller, the toner image formed on the image carrier is transferred from the primary transfer position to the intermediate transfer member. A distance on the intermediate transfer member from a position on the intermediate transfer member to a secondary transfer position at which the combined toner image is collectively transferred onto transfer paper is set to be equal to or longer than a maximum image output length.

  In the color image forming apparatus according to claim 1, since the intermediate transfer belt is disposed obliquely and the lower sheet is fed and the upper sheet is discharged, the apparatus main body can be adjusted to a just-balanced size. The transport path to the paper section can be shortened, the transport quality can be stabilized, and the transfer paper transport path for jam clearance is opened on the front side of the main body of the machine, so the jam clearance operation is easy to understand. In addition, since it is possible to perform only the jam processing without operating the image forming unit, there is an effect that troubles such as a toner drop can be eliminated.

  In the color image forming apparatus according to the second aspect, for example, in a belt photoconductor surface contact development method, even if toner is scattered from the development roller due to the contact / separation operation of the development roller, the photoconductor surface does not exist in the lower portion. In addition to the effects described above, the photosensitive member can be prevented from adhering to the photosensitive member, so that a color image without color mixture can be obtained.

  In the color image forming apparatus according to the third aspect, by providing the transfer paper conveyance path substantially in parallel with the intermediate transfer belt surface, in addition to the above-described common effects, the front surface of the apparatus main body can be thinned, and the apparatus main body can be downsized. There is an effect that the transfer route can be simplified and shortened.

  In the color image forming apparatus according to claim 4, since the writing unit is provided in the lower portion of the apparatus main body, in addition to the above-described common effects, the apparatus main body immovable section housing is not a movable section housing for jam processing and unit replacement. In addition, there is an effect that the color shift at the time of a color image due to vibration or the like can be prevented and the positioning with the side plate supporting the photoconductor reference axis can be accurately performed.

  In the color image forming apparatus according to the fifth aspect, by using a belt as the image carrier, in addition to the above-described common effects, the unit can be thinned, the apparatus main body can be downsized, and the belt surface between the rollers is long. Since the belt surface is vertical or slightly inclined, there is an effect that a plurality of developing units can be arranged in parallel to the belt surface without worrying about mixing of developing toner on the photosensitive member. Further, since the intermediate transfer belt is inclined and the photoreceptor belt is made substantially vertical, there is also an effect that a space for the capacity of the waste toner collecting container can be secured.

  In the color image forming apparatus according to the sixth aspect, the distance on the intermediate transfer body from the primary transfer position to the secondary transfer position is equal to or longer than the maximum image output length. Even if the speed of the intermediate transfer belt fluctuates due to the contact with the intermediate transfer belt, there is also an effect that the transfer blur of the toner image on the photoconductor and the intermediate transfer belt can be prevented.

  An embodiment of a color image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the color image forming apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a flexible belt-shaped photoreceptor serving as a belt-shaped image carrier, and the photoreceptor belt 1 is bridged between rotating rollers 2 and 3 to drive the rotating rollers 2 and 3. Is conveyed clockwise. 4 is a charging charger as charging means, 5 is a laser writing system unit as image exposure means, 6 is three developing means containing yellow, magenta and cyan color developers, that is, a rotary type color developing device, and 7 is a color developing device. This is a black developing device that is provided separately from the developing device 6 and is a developing unit that contains a black developer.

  The laser writing system unit 5 rotates and scans a laser beam generated by a semiconductor laser (not shown) by a polygon mirror 5B rotated by a drive motor 5A, and the optical path is bent by a mirror via an fθ lens 5C. The circumference of the photoreceptor belt 1 uniformly charged by the charging charger 4 is exposed to form an electrostatic latent image. For this reason, the laser writing system unit 5 is housed in a holding housing provided with a slit-shaped exposure opening on the upper surface and incorporated in the apparatus main body. A bottom plate (not shown) is provided above the paper feed cassette 17 and below the writing system unit 5. The writing system unit 5 is incorporated therein, and the side plates of the apparatus main body are moved right and left in the roller axis direction to support each unit. Provided and assembled to the bottom plate. As the laser optical system 5, an optical system or the like in which a light emitting unit and a convergent light transmitting body are integrated is used in addition to the illustrated one. The charging charger 4, the laser writing light 5D, and the photoconductor cleaning blade 15A are provided on the rotating roller 2 side on which the photoconductor belt 1 is laid.

  Each of the color developing device 6 and the black developing device 7 includes a developing roller which comes close to or in contact with the photosensitive belt 1 at a predetermined position, and develops a latent image on the photosensitive belt 1 by non-contact development or contact development. It has the function of imaging. Reference numeral 10 denotes an intermediate transfer belt, which is an intermediate transfer member. The intermediate transfer belt 10 is laid between the rotating rollers 11 and 12 and is inclined, and is conveyed counterclockwise by driving the rotating rollers 12 and 13. Is done. On the lower inclined belt surface of the intermediate transfer belt 10, the photosensitive belt 1 and the intermediate transfer belt 10 are in contact with each other at the position of the rotating roller 3, and the first visible image on the photosensitive belt 1 is The image is transferred onto the intermediate transfer belt 10 by the bias brush 13 provided in the transfer belt (primary transfer position), and by repeating the same process, the second visualization, the third visualization, The fourth visual image is superimposed on the intermediate transfer belt 10 and transferred so as not to cause a positional shift. A transfer roller 14 as a secondary transfer member is provided above the rotation roller 11 of the intermediate transfer belt 10 so as to be in contact with and separate from the intermediate transfer belt 10. The distance on the intermediate transfer belt 10 from the primary transfer position to the secondary transfer position is set to be equal to or longer than the maximum image output length. In the figure, reference numeral 15 denotes a waste toner collecting container including a cleaning blade 15A of the photoreceptor belt 1, 16 denotes a cleaning device of the intermediate transfer belt 10, and a blade 16A of the cleaning device 16 is separated from the surface of the intermediate transfer belt 10 during image formation. And is pressed against the surface of the intermediate transfer belt 10 as shown in the drawing only during cleaning after the secondary transfer of the image.

  FIG. 2 shows the internal configuration of the color and black developing units 6 and 7, and FIG. 3 is a perspective view of the color developing unit 6. The rotary color developing device 6 is provided with a casing 21 as a rotating body rotatably about a rotation center O. The casing 21 can be rotated clockwise in the figure by driving of a drive mechanism (not shown). Has become. The casing 21 integrally holds the yellow, magenta, and cyan developing units 22 (-Y, M, and C). The developing units 22 (-Y, M, C) of each color take the same form and the same operation.

  The photoreceptor belt 1 laid between the rotating rollers 2 and 3 is arranged with the belt surface inclined vertically or slightly obliquely, and the color developing device 6 is arranged at the lower part and the black developing device 7 is arranged at the upper part in parallel. is there. As described above, since the intermediate transfer belt 10 is inclined and the photoreceptor belt 1 is substantially vertical, a space of a certain capacity can be secured in the waste toner collecting container 15.

  At the developing position in the color developing device 6, the developing roller 23 is disposed opposite to the photosensitive belt 1 so as to rotate in the same direction as the moving direction of the photosensitive belt 1 with a predetermined linear velocity ratio. Is done. Below the developing roller 23, a supply roller 25 made of an elastic material such as foamed polyurethane is rubbed with the developing roller 28 in the rubbing portion, and is rotated in the same direction as the developing roller 23 at a predetermined linear velocity ratio. Is provided. A developing blade 26 made of a thin plate having a spring property such as stainless steel is provided downstream of the supply roller 25 in the rotation direction such that one end thereof is in contact with the developing roller 23.

  As shown in FIG. 3, a toner container 29 is provided on the front side of the developing device 6. The developing roller 23 and the supply roller 25 are arranged in parallel to the side plate of the unit 22 so as to convey the toner from the front to the rear of the drawing. In addition to being interlocked with the developing roller 23 and the supply roller 25, the developing roller 23 and the supply roller 25 rotate at a predetermined linear velocity ratio. The developing unit partition plate 24 is disposed so that a part thereof is in contact with the supply roller 25, and a toner transport space surrounding the first toner transport member 27 is formed by the developing roller 23, the supply roller 25, and the like. . The toner supplied onto the supply roller 25 is supplied to the surface of the developing roller 23 by the supply roller 25, charged, and carried on the surface of the developing roller 23. The toner carried on the surface of the developing roller 23 is thinned by the developing blade 26 to develop the electrostatic latent image formed on the surface of the photoreceptor belt 1.

  By the way, the toner not used in the developing step is transported by the first toner transporting member 27 to the rear end of the developing device 6 on the side opposite to the toner storage unit 29, and the axial direction of the developing roller 23 and the supply roller 25 is changed. The toner reaches the toner circulating portion provided outside the effective diameter portion, and the toner falls to the lower portion of the developing unit 22 by gravity. Below the developing unit 22, a second toner conveying member 28 also having a screw shape is disposed in parallel with the developing roller 23, the supply roller 25, and the first toner conveying member 27. Rotates so as to convey the toner in the reverse direction, and conveys the toner not used in the developing process to the toner storage unit 29. By appropriately setting the amount of toner transported by the first toner transport unit 27 and the second toner transport member 28, the amount of toner supplied to the supply roller 25 can be adjusted without detecting the amount of toner in the developing unit 22 or performing complicated toner supply amount control. And a small color developing unit 6 having a large degree of freedom in layout and a small cross-sectional occupation ratio with respect to the photosensitive belt 1. The toner cartridge 30 shown in FIG. 3 is detachable from the toner container 29 so that the toner cartridge 30 can be replaced when toner is supplied.

  The black developing device 6 is a developing device in which black toner is contained in a developing container 41, and is a developing device integrally formed as a so-called developing cartridge in which the life of the developing device is replaced when the toner is exhausted. Similarly to the developing unit 22 of the color developing device 7, the developing roller 23 is opposed to the photosensitive belt 1 such that the developing roller 23 rotates in the same direction as the moving direction of the photosensitive belt 1 at a predetermined linear velocity ratio. Will be arranged. Above the developing roller 23, a supply roller 25 made of an elastic body such as foamed polyurethane is rubbed with the developing roller 23 at the rubbing portion, and is rotated in the same direction as the developing roller 23 at a predetermined linear velocity ratio. Further, a developing blade 26 made of a thin plate having a spring property such as stainless steel is provided so that one end thereof is in contact with the developing roller 23. A paddle 42 having a plurality of blade-like portions for stirring the toner near the developing blade 26 is provided in the developing container 41, and a first agitator for conveying and stirring the toner to the supply roller 25 and the developing roller 23 side. 43 and a second agitator 44 are provided. Here, a developing cartridge of a type containing toner is used, but a developing device of a type that replaces and replenishes a toner cartridge, such as a color developing device, may be used. Further, the black developing device 7 can swing in the horizontal direction with respect to the photosensitive belt 1, moves away from the photosensitive belt 1 during non-development, and approaches or contacts the photosensitive belt 1 during development.

  As the process cartridge 31, the photoreceptor belt 1, the charging charger 4, the intermediate transfer belt 10, the cleaning device 16, and the registration roller 20 </ b> B are integrally formed, and the waste toner collecting container 15 is exchangeably incorporated into the process cartridge 31. Have been. The surface of the registration roller 20B in the case exterior part of the process cartridge 31 also has a function as a conveyance guide.

  Here, the waste toner scraped off from the intermediate transfer belt 10 by the cleaning blade 16A is conveyed in the sectional front side by the auger 16B provided in the cleaning device 16, and further provided on the front side surface of the process cartridge 31. The toner is conveyed to a waste toner collecting container 15 by a conveying member (not shown) and collected. As a result, the waste toner can be collected without replacing the process cartridge 31, so that the life of the process cartridge can be extended.

  The transport path to the transport roller 19, the registration roller 20, the transfer roller 14, and the fixing device 50 is arranged substantially in parallel with the inclined belt surface of the intermediate transfer belt 10 to reduce the size of the apparatus main body.

  The image forming process by the above-described color image forming apparatus is performed as follows. First, the formation of a multicolor image is performed according to the image forming system described below. That is, data obtained by a color image data input unit in which an image sensor scans an original image is processed by an image data processing unit to create image data, which is temporarily stored in an image memory. Next, the image memory is taken out at the time of recording and input to a recording section, for example, a color image forming apparatus shown in the apparatus of FIG. That is, when a color signal output from an image reading device separate from the printer is input to the laser writing system unit 5, a laser beam generated by a semiconductor laser (not shown) in the laser writing system 5 Rotational scanning is performed by a polygon mirror 5B rotated by a drive motor 5A, the optical path is bent by a mirror via an fθ lens 5C, and the circumference of the photoreceptor belt 1 is uniformly charged in advance by a charging charger 4 as charging means. To form an electrostatic latent image.

  Here, the image pattern to be exposed is a single-color image pattern when a desired full-color image is separated into yellow, magenta, cyan, and black. The formed electrostatic latent images of three colors are developed by the rotation operation of the rotary type color developing device 6 by sequentially developing the yellow, magenta, and cyan developing units against the photoreceptor belt 1, and are developed and made monochromatic. A monochromatic image is formed (at this time, the black developing device 7 is retracted to the non-development position with respect to the photosensitive belt 1), and the black electrostatic latent image is developed by the black developing device 7 and becomes visible. The color is converted to a single color to form a single-color image. The monochrome image formed on the photoreceptor belt 1 is sequentially superimposed and transferred onto an intermediate transfer belt 10 rotating counterclockwise while contacting the photoreceptor belt 1. The yellow, magenta, cyan, and black images superimposed on the intermediate transfer belt 10 are transported from the paper cassette 17 to the transfer unit via the paper feed roller 18, the transport roller 19, and the registration roller 20, and the transfer roller 14 The transfer belt contacts the rotating roller 11 of the transfer belt via transfer paper and is transferred. At this time, when the transfer roller 14 comes into contact, as described above, it has passed through the primary transfer portion at the image rear end on the intermediate transfer belt. After the transfer is completed, the transfer paper is fixed by the fixing device 50 to complete a full-color image.

  Next, the configuration of the apparatus main body will be described with reference to FIGS. The apparatus main body structure includes a main body frame 9 serving as an immovable portion housing and a front frame 8 serving as a front housing capable of opening a transfer paper transport path. A paper feed cassette 17 is disposed below the main body frame 9. Each of the developing units and the process cartridge is replaceably disposed at the center, and the fixing device 50 is disposed above the developing unit and the process cartridge.

  The front frame 8 is supported so as to be rotatable around a rotation support shaft 9A provided on the main body frame 9 serving as a rotation fulcrum. At the time of image formation output, the front frame 8 is attached to the main body frame 9 as shown in FIG. Is held. By releasing the holding during the jam clearance, the opening can be opened clockwise, and the open state can be maintained by the power of a tension spring or the like. The front frame 8 holds a registration roller 20A, a transfer roller 14, and the like, which are part of the transport path. As a result, when the front frame 8 is opened, the transport path is opened as shown in FIG. 4, and the paper jam processing is performed. At this time, since only the jam processing can be performed without operating the image forming unit, there is no problem such as toner drop.

  Further, the main body frame 9 holds an intermediate frame 40 which holds the process cartridge 31 in a configuration to be described later and is supported so as to be rotatable about a rotation support shaft 9B provided on the main body frame 9 serving as a rotation fulcrum. They are provided on the left and right as shown in FIG. The intermediate frame 40 is normally held by the main body frame 9 (other than when the process cartridge and each developing unit are replaced), and can be opened clockwise by releasing the holding.

  FIG. 6 shows the attachment / detachment position of the process cartridge 31, and FIG. 7 shows the attachment / detachment state of the process cartridge 31. Rail-shaped projections 32 are provided on both side surfaces of the process cartridge 31 so as to be parallel to the attaching / detaching operation direction. Correspondingly, rail-shaped projections 32 are also provided on the intermediate frame 40 to be parallel to the attaching / detaching operation direction. A groove 40A is provided. For this reason, at the time of mounting, the process cartridge 31 is held by the intermediate frame 40. If the process cartridge 31 is operated in the direction of the arrow while the intermediate frame 40 is supported and fixed at the position shown in FIG. 6, the process cartridge 31 can be more easily attached and detached than the intermediate frame 40. In particular, if the handle 33 is provided in front of the process cartridge 31, the operability is further increased. The groove 40A can be mounted without any problem as long as the process cartridge 31 insertion side is opened in a trumpet shape.

  Here, the operation direction of the process cartridge 31 is a direction in which the process belt 31 is stretched over two rollers of the intermediate transfer belt 10, and the belt surface on which the photosensitive belt 1 is stretched is substantially parallel to the intermediate transfer belt surface. As a result, the space between development and transfer can be reduced, and the cross section of the apparatus main body can be reduced.

  The intermediate frame 40 can be further opened to the attachment / detachment position of the process cartridge 31, and reaches the same position as the opening position of the front frame as shown in FIG. At this position, the intermediate frame 40 is supported and fixed while the process cartridge is mounted, so that the developing units 6 and 7 disposed on the back side of the process cartridge can be enlarged without temporarily retreating the process cartridge out of the apparatus main body. Since the developing units 6 and 7 are opened, the operability of attaching and detaching the developing units 6 and 7 is improved.

  Here, as an example of a mechanism for supporting and fixing the intermediate frame 40 in two stages, as shown in FIG. 7, two grooves are provided below the rotation fulcrum of the intermediate frame 40, and the leaf spring 34 is indicated by an arrow in the figure. It is built into the body frame so as to swing with a constant spring force in the direction. The swinging distal end portion 34A of the leaf spring 34 corresponds to the grooves 40B and C when the intermediate frame 40 is rotated and enters and latches and supports and fixes the intermediate frame 40 in two stages. At this time, the position of the process cartridge 31 in the attaching / detaching rotational direction is supported and fixed at a position such that the center of gravity position G of the process cartridge is substantially on the vertical line of the rotation center position of the intermediate frame 40, and the attaching / detaching moving direction is substantially vertical. By adjusting the position of the handle, the spring force of the leaf spring 34 for supporting and fixing the process cartridge is small, a sense of stability is obtained when the intermediate frame 40 is rotated, and the process cartridge is not gravity Can be operated without falling into a stable state. Also, if the intermediate frame 40 is used as a stopper member for stopping rotation by using a part of the front frame at the second support fixed position, the groove 40C of the intermediate frame 40 can be eliminated.

  FIG. 9 is a sectional view showing another embodiment of the color image forming apparatus according to the present invention. This embodiment is different from the previous embodiment in that a photosensitive drum 1 'is used in place of the photosensitive belt and the developing units are all integrated type rotary developing devices 6'. Since the photosensitive drum 1 'is used, the developing space is narrower than in the previous embodiment. Therefore, the developing position is set to one by using the rotary developing device 6' for four colors. As shown in the drawing, even if toner is scattered from the developing roller 23 due to the contact / separation operation of the developing roller 23, the developing position is set at a position below the photosensitive member surface where no photosensitive member surface exists. The toner cartridges of the respective colors of the rotary developing device 6 'are arranged outside the transfer paper transport path, so that the toner cartridge can be replaced regardless of the process cartridge. Note that other configurations and operations are almost the same as those of the previous embodiment, and thus description thereof is omitted.

FIG. 1 is a cross-sectional view illustrating one embodiment of a color image forming apparatus of the present invention. FIG. 2 is a cross-sectional view illustrating an internal configuration of a color and black developing device of the color image forming apparatus of FIG. 1. FIG. 2 is a perspective view of a color developing device of the color image forming apparatus of FIG. 1. FIG. 2 is a cross-sectional view of the color image forming apparatus of FIG. 1 with a front frame opened. FIG. 3 is a perspective view of a process cartridge and an intermediate frame for supporting the process cartridge. FIG. 4 is a cross-sectional view illustrating a mounting / detaching position of a process cartridge. FIG. 4 is a side view illustrating a detached state of a process cartridge. It is sectional drawing of the opened state of an intermediate | middle frame. FIG. 7 is a cross-sectional view illustrating another embodiment of the color image forming apparatus of the present invention.

Explanation of reference numerals

1 photoreceptor belt 1 'photoreceptor drum 2, 3 rotating roller 4 charging charger 5 laser writing system unit 6 color developing unit 6' rotary developing unit 7 black developing unit 8 front frame 9 main body frame 10 intermediate transfer belts 11, 12 Rotating roller 13 Bias brush 14 Transfer roller 15 Waste toner collection container 16 Intermediate transfer belt cleaning device 17 Paper feed cassette 18 Paper feed roller 19 Transport roller 20 Registration roller 21 Casing 22 Color developing unit 23 Developing roller 24 Partition plate 25 Supply roller 26 developing blade 27 first toner conveying member 28 second toner conveying member 29 toner container 30 color toner cartridge 31 process cartridge 32 rail projection 33 handle 34 leaf spring 40 intermediate frame 41 developing container 42 paddle 43 first agitator 4 Second agitator 50 fixing device

Claims (6)

The toner image formed on the image carrier is repeatedly transferred to an intermediate transfer body, a plurality of toner images are superimposed on the intermediate transfer body to form a synthetic toner image, and the synthetic toner image is formed on the intermediate transfer body. In a color image forming apparatus that collectively transfers and fixes onto transfer paper,
One belt surface of a belt-shaped intermediate transfer member bridged by at least two rollers is arranged at an angle, and the image carrier is arranged below the inclined belt surface to transfer the toner image of the image carrier. And a paper feed unit disposed below the apparatus main body and a paper discharge unit disposed above the apparatus main body, and a transfer paper transport path extending in a direction from the paper supply unit to the paper discharge unit is provided. Image forming device. In the developing device for developing the electrostatic latent image formed on the image carrier, the contact position of the developing roller at the developing position on the image carrier is vertical or the contact position of the developing roller is on the lower side. 2. The color image forming apparatus according to claim 1, wherein the developing device and the image carrier are arranged at a slight inclination. 3. The color image forming apparatus according to claim 1, wherein a part of the transfer paper transport path is formed substantially in parallel with the inclined belt surface of the intermediate transfer body. 4. A color image forming apparatus according to claim 1, wherein a writing unit for forming an electrostatic latent image on said image carrier is provided at a lower portion of the apparatus main body. The color image forming apparatus according to any one of claims 1 to 4, wherein the image carrier has a belt member provided with at least two roller members. The intermediate position from a primary transfer position at which the toner image formed on the image carrier is transferred to the intermediate transfer member to a secondary transfer position at which the synthetic toner image is collectively transferred from the intermediate transfer member to transfer paper 6. The color image forming apparatus according to claim 1, wherein a distance on the transfer body is equal to or longer than a maximum image output length.

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