JPH103215A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability and to accurately position a black developing device by providing a guiding member for supporting the black developing device so that is can rock in a direction perpendicular to the bus of an image carrier in a device main body and providing a rail part for attaching the black developing device in the same direction as the bus of the image carrier in the guiding member. SOLUTION: The guiding member 50 for attaching the black developing device 21B is arranged to freely rock on both side walls 60F and 60R in the device main body. The member 50 is equipped with a guide arm front, a guide rear 50R and the guide rail 50G coupling both of them. The device 21B and the member 50 are allowed to integrally rock and accurately positioned with respect to the image carrier. When the device 21B is set at a developing position, the attitude of a rotating lever 51 is a perpendicular direction and the lever 51 covers a part of a black developing device insertion port 54. In the case of taking out the device 21B from the device main body, the lever 51 is rotated to take a horizontal attitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and has a developing device.

[0002]

2. Description of the Related Art First, the configuration of a conventional color laser printer will be briefly described with reference to FIG.

[0003] The primary charger has a configuration in which a charging roller 104b to which a voltage is applied is pressed against an image carrier 104a. The charging roller 104b is used for the image carrier 104a.
Before forming a latent image on the surface, the surface thereof is uniformly charged.

Exposure to the image carrier 104a is performed by a scanner unit 110a having a laser diode. The laser diode emits light corresponding to the image signal and irradiates the polygon mirror. The reflected laser light scans the image carrier in the generatrix direction by a polygon mirror rotating at high speed. Then, the coupling lens 11
0b and the image carrier 104a via the reflection mirror 110c
It is collected on the surface of.

The image carrier (photosensitive drum) 104a
Is exposed by condensing a laser beam corresponding to an image signal, and an electrostatic latent image of each color is formed.

The rotary developing device 105 includes developing units for each color, that is, developing units 105M, 105C, 105Y, and 105K containing magenta, cyan, yellow, and black toners.
It has.

[0007] These four color developing units are arranged rotatably with respect to a shaft 105e. The center of each developing unit rotates in conjunction with a rotating gear disposed on the outer periphery of the revolving gear, and its posture is maintained constant.

[0008] Further, in the four color developing units, the amount of stored toner is the same so that the torque distribution to the shaft 105e becomes uniform. In this example, a standard image of A3 size contains toner of a capacity capable of printing 3000 sheets.

At the time of image formation, developing units 105M (105C, 105Y, 105K) of colors corresponding to the latent images are provided.
It stands still at a position facing the image carrier 104a. Further, at that position, the developing roller 105b is positioned so as to be opposed to the surface of the image carrier 104a with a small gap.

The developing device 105M (105C, 105Y, 1
05K) is moved to the developing position, a connection is made to the high-voltage power supply of the apparatus main body, and a bias is applied to the developing roller 105b. At the same time, it is coupled to driving means from a driving source of the apparatus main body.

As described above, when the developing roller 105b receives the bias application and the rotational driving, the latent image on the image carrier is developed and a toner image is formed.

On the other hand, a paper feeding unit 101
Are arranged, and the transfer material 102 is fed to the transfer drum 103. The transfer material 102 is supplied to the sheet feeding cassette 101a.
It is stored in. Then, the paper feed roller 101b rotates in accordance with the image forming operation, and the transfer material 102 is separated one by one from the cassette 101a and fed to the transfer drum 103.

A transfer drum 102 is wound around a transfer material 102 fed from a paper supply unit 101. On the outer circumference of the transfer drum 103, an electrostatic suction roller 1
03g is provided.

The electrostatic attraction roller 103g is used to transfer the transfer material 10
2 is pressed into contact with the transfer drum 103. At this time, by applying a bias between the electrostatic attraction roller 103g and the transfer drum 103,
The transfer material 102 is electrostatically attracted to the outer periphery of the transfer drum 103. Then, the toner images of each color on the image carrier 104a are transferred onto the transfer material 102 in the transfer section.

When the transfer of the magenta toner image is completed, the next developing device 105C rotates, and the image carrier 104 is rotated.
a is located at the developing position opposite to a. In the same process, latent images of cyan, yellow, and black and development are sequentially performed, and the obtained toner image is transferred onto the transfer material 102 to form a full-color image.

That is, one full-color image of four colors can be obtained by rotating the transfer drum 103 holding the transfer material 102 four times.

The cleaner 104d includes an image carrier 104a.
This is for cleaning the toner remaining on the upper side, and is arranged on the outer periphery of the image carrier 104a downstream of the transfer section.

Transfer material 10 after transfer of four-color toner image is completed
2 is separated from the transfer drum 103 and transported to the fixing unit 106.

The fixing unit 106 includes a pressure roller 106a
And a fixing roller 106b that presses against the transfer material and applies heat and pressure to the transfer material. The fixing roller 106b passes through the transfer material 102 that has been peeled and conveyed from the transfer drum 103 so that each color toner image is transferred to the transfer material. 102.

Finally, the transfer material 102 is fixed to a toner image by a fixing unit 106 and then discharged to a discharge tray 108 by a discharge roller pair 107.

[0021]

In the current business market, printers and the like are generally used by a plurality of users by connecting them to a network such as a personal computer. It is used for a large amount of high-speed output.

On the other hand, most of the color printers currently in widespread use are not suitable for a large amount of monochrome images and high-speed output, and are often used exclusively for color documents. Therefore, the user often uses either the monochrome printer or the color printer in accordance with the purpose and type of the document.

[0023] Such proper use is effective in an environment where the types of documents to be output are limited, but is considered to be ineffective in a business market where various documents can be output.

From this point of view, it is expected that a future network-dedicated color printer will have to cope with a large number of monochrome images and high-speed output regardless of whether a color document can be output. .
Then, in the above-mentioned usage form, it can be said that the cost per page also needs to be reduced to the level of a monochrome printer.

In order to realize a large amount and high-speed output of the monochrome document, it is necessary to increase the toner capacity of the black developing device to the level of a conventional monochrome network printer.

However, in the above-mentioned conventional example, the four color developing units 105M, 105C, 105Y and 105K are all arranged in the rotary 105R. With such a configuration, when the toner capacity of the developing device for a specific color is increased,
The torque balance during rotation of the rotary 105R is lost,
It is difficult to perform stable rotation.

For this reason, there is a possibility that shortage of the switching time of the developing unit, deviation of the stop position of the developing unit, and the like may occur, resulting in inconvenience that a good image cannot be formed.

Accordingly, an object of the present invention is to provide at least an image forming apparatus having a black developing device capable of storing a large amount of toner, in which an operability is improved and an accurate positioning of the black developing device is realized. It is to provide.

[0029]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
In an image forming apparatus having at least an image carrier on which a latent image is formed and a black developing device for developing the latent image to form a developed image, the apparatus body swings in a direction perpendicular to the generatrix of the image carrier. An image forming apparatus, comprising: a guide member supported so as to be capable of supporting the black developing device in the same direction as a generatrix of the image carrier.

The guide member has the rail portion for guiding the mounting of the black developing device, and an arm portion for supporting the rail portion in the longitudinal direction. The rail portion or the arm portion has the black portion. It is preferable that a positioning portion of the developing device is formed, and one end of the arm portion is supported so as to be swingable in a direction perpendicular to a generatrix of the image carrier.

The black developing device and the guide member swing together and a part of the black developing device is retracted from the first position where the black developing device can contact the image carrier and the image carrier. It is preferable to be supported movably between the second position. A rotatable lever is located on the front side of the device body,
In conjunction with the rotation of the lever, a part of the black developing device performs a contact / retreat operation between the first position and the second position. In the second position, the lever is provided on the apparatus main body. It is preferable that the black developing device is disposed at a position to close the insertion opening.

According to another aspect of the present invention, at least an image carrier on which a latent image is formed, a black developing device for developing the latent image into a developed image, and a rotary device on which a plurality of color developing devices are arranged An image forming apparatus having a guide member that is supported by the apparatus main body so as to be swingable in a direction perpendicular to the generatrix of the image carrier, and the guide member connects the black developing device to the image carrier. There is provided an image forming apparatus having a guide portion to be mounted in the same direction as the generatrix.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Overall Description of Image Forming Apparatus] First, the overall configuration of a color image forming apparatus will be schematically described with reference to FIG. FIG. 1 shows a color laser printer which is an embodiment of a color image forming apparatus.

The image forming section of the color laser printer includes an image carrier (photosensitive drum) 15 rotating at a constant speed.
And a fixed type black developing unit 21B, and three rotatable color developing units (yellow developing unit 20Y, magenta developing unit 20M, and cyan developing unit 20C).

Substantially below the image forming section, an intermediate transfer member 9 for holding a developed and multi-transferred color image and further transferring the color image to the transfer material 2 fed from the feeding section.
Is arranged.

The transfer material 2 on which the color image has been transferred
Is transported to the fixing unit 25 to fix the color image on the transfer material 2, and is discharged to the discharge unit 37 on the upper surface of the apparatus by discharge rollers 34, 35, and 36.

The three-color rotary developing device and the fixed-type black developing device are configured to be individually detachable from the printer main body.

Next, the configuration of each part of the image forming apparatus will be described in detail sequentially.

[Image Carrier Unit] The drum unit 13, which is an image carrier unit, includes an image carrier (photosensitive drum) 1
5 and a container 14 of a cleaning device also serving as a holder for the image carrier 15 are integrally formed. The drum unit 13 is detachably supported by the printer main body, and is configured so that the unit can be easily replaced according to the life of the image carrier 15.

The image carrier 15 according to this embodiment has a diameter 62
mm of an aluminum cylinder is coated with an organic photoconductor layer on the outside thereof.
It is supported rotatably.

A cleaner blade 16 and a primary charging means 17 are arranged on the periphery of the image carrier 15, and a driving force of a drive motor (not shown) is transmitted to one end of the image carrier 15 so that the image carrier 15 is driven. 15 is rotated counterclockwise in the figure according to the image forming operation.

[Charging Means] The primary charging means 17 employs a contact charging method.
5, the surface of the image carrier 15 is uniformly charged by applying a voltage to the conductive roller.

[Exposure Means] Exposure to the image carrier 15 is performed from the scanner unit 30. That is, when an image signal is given to a laser diode, the laser diode irradiates an image corresponding to the image signal to a polygon mirror.

The polygon mirror 31 is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror 31 selectively passes through the imaging lens 32 and the reflection mirror 33 to the surface of the image carrier 15 rotating at a constant speed. Exposure causes an electrostatic latent image to be formed on the image carrier 15.

[Developing Means] The developing means comprises three rotary developing devices 20 for developing each color of yellow, magenta, cyan and black in order to visualize the electrostatic latent image.
Y, 20M, 20C and one black developing unit 21B.

The black developing device 21B is a fixed developing device, and a developing sleeve 21B is provided at a position facing the image carrier 15.
S is a minute distance from the image carrier 15 (about 300 μm)
To form a visible image on the image carrier 15 using black toner.

The black developing unit 21B feeds the toner in the container by a toner supply roller 21BR by a feed mechanism 21BT.
The toner is applied to the outer periphery of the developing sleeve 21BS that rotates clockwise in the figure by the application blade 21BB pressed against the outer periphery of the developing sleeve 21BS, and a charge is applied to the toner (friction charging).

By applying a developing bias to the developing sleeve 21BS, reversal development (jumping development) is performed corresponding to the electrostatic latent image on the image carrier 15, and the electrostatic latent image on the surface of the image carrier 15 is formed. It is visualized as a toner image.

The toner capacity of the black developing unit 21B is 15,000 pages (A4, 5% printing) which is more than twice the toner capacity of the rotary developing units 20Y, 20M and 20C in consideration of the documents and image patterns handled by the user and the toner consumption. ) Equivalent.

By increasing the capacity of the black developing device in this way, it is possible to reduce the frequency with which the user replaces the black developing device and also reduce the running cost per print.

Further, as shown in FIG. 1, the black developing device 21B is disposed at an intermediate position between the laser scanner 30 as an exposure device and the rotary developing devices 20Y, 20M and 20C. , 20M,
This prevents toner leaking when the 20C rotates from scattering to optical components such as a laser scanner.
As a result, it is possible to prevent the toner from adhering to the polygon mirror, the lens, the mirror, and the like, thereby preventing the latent image from being formed, and to obtain a clear output.

Three rotating developing units 20Y, 20M, 20C
, Each containing toner corresponding to 6000 pages (A4, 5% printing), and held detachably on a developing rotary 23 that rotates about a shaft 22.

At the time of image formation, each developing device is rotated around a shaft 22 while being held by a developing rotary 23, a predetermined developing device is stopped at a position facing the image carrier 15, and a developing sleeve is further moved. After being positioned so as to face the image carrier 15 at a small interval (about 300 μm), a visible image is formed corresponding to the electrostatic latent image on the image carrier 15.

When a color image is formed, the developing rotary 23 rotates for each rotation of the intermediate transfer member 9 and the yellow developing device 20 rotates.
The developing process is performed in the order of Y, magenta developing device 20M, cyan developing device 20C, and then black developing device 20B.

For example, when the yellow developing unit 20Y carries out the developing step, the yellow developing unit 20Y is positioned and stopped at a position facing the image carrier unit 13, and sends the toner in the container to the application roller 20YR by a feed mechanism. Coating roller 20YR and developing sleeve 20 rotating clockwise in the figure
The blade 20 </ b> YB pressed against the outer periphery of the YS applies a thin layer of toner to the outer periphery of the developing sleeve 20 </ b> YS rotating clockwise in FIG.

By applying a developing bias to the developing sleeve 20YS facing the image carrier 15 on which the latent image is formed, toner development is performed on the image carrier 15 in accordance with the latent image.

Magenta developing device 20M, cyan developing device 20
For C, toner development is performed by the same mechanism as described above.

Each of the rotary developing devices 20Y, 20M, 20C
When each developing device is rotated to the developing position, each developing sleeve is connected to a high-voltage power supply for each color development provided in the printer main body and a drive, and a voltage is sequentially and selectively applied for each color development. The drive is applied and transmitted.

[Intermediate Transfer Body] In the intermediate transfer body 9, during the color image forming operation, the toner image on the image carrier 15 visualized by each developing device is printed four times (each of four colors of Y, M, C, and B). (Image), it is rotated clockwise in the figure in synchronization with the outer peripheral speed of the image carrier 15. In addition, the intermediate transfer body 9 that has undergone the multiple transfer transfers the transfer material 2 between the transfer roller 10 to which a voltage is applied, and conveys the toner image. I do.

The intermediate transfer member 9 according to this embodiment has a diameter of 18
The outer circumference of a 6 mm aluminum cylinder 12 is covered with an elastic layer 11 of medium resistance sponge, medium resistance rubber or the like.
The intermediate transfer body 9 is rotatably supported, and is rotated by being driven by an integrally fixed gear (not shown).

[Cleaning Unit] The cleaning unit cleans the toner remaining on the image carrier 15 after the toner visualized on the image carrier 15 by the developing unit is transferred to the intermediate transfer member 9. Things. Then, the cleaned waste toner is stored in the container 14. The amount of waste toner stored in the container 14 does not fill the container 14 earlier than the life of the image carrier, and therefore,
The container 14 is simultaneously replaced when the life of the image carrier 15 is replaced.

[Paper Feeding Unit] The paper feeding unit feeds the transfer material 2 to the image forming unit, and includes a cassette 1 containing a plurality of transfer materials 2, paper feed rollers 3 and 4, and double feed prevention. , A paper feed guide 6, and a registration roller 8.

At the time of image formation, the paper feed roller 3 rotates according to the image forming operation, separates and feeds the transfer material 2 in the cassette 1 one by one, guides the transfer material 2 by the guide plate 6, and passes through the transport roller 7. To the registration roller 8.

During the image forming operation, the registration roller 8
A non-rotating operation for causing the transfer material 2 to stand still and a rotating operation for transporting the transfer material 2 toward the intermediate transfer body 9 are performed in a predetermined sequence. Alignment with.

[Transfer Section] The transfer section is composed of a swingable transfer roller 10. The transfer roller 10 has a metal shaft wound with a medium-resistance foamed elastic material, and can be moved up and down in the figure and driven. Having.

While the four-color toner image is being formed on the intermediate transfer member 9, that is, while the intermediate transfer member 9 is rotated a plurality of times, the transfer roller 10 is indicated by a solid line in FIG. It is located below and separated from the intermediate transfer member 9.

After the formation of the four color toner images on the intermediate transfer member 9, the transfer roller 10 is shown by a thin line in the figure by a cam member (not shown) in accordance with the timing of transferring the color image onto the transfer material 2. At the upper position, it is pressed against the intermediate transfer body 9 via the transfer material 2 with a predetermined pressure. At this time, a bias is simultaneously applied to the transfer roller 10, and the toner image on the intermediate transfer body 9 is transferred to the transfer material 2.

Here, since the intermediate transfer member 9 and the transfer roller 10 are driven respectively, the transfer material 2 sandwiched between the two is subjected to the transfer process and at the same time, at a predetermined speed in the left direction in the figure. And is sent to the fixing unit 25 which performs the next process.

[Fixing Unit] The fixing unit 25 includes a developing unit 20,
The toner image formed on the transfer material 2 is fixed on the transfer material 2 through the intermediate transfer body 9 by the toner image formed by the fixing member 21. As shown in FIG. 1, a fixing roller 26 for applying heat to the transfer material 2 is used. And a pressure roller 27 for pressing the transfer material 2 against the fixing roller 26. Each roller 2
6 and 27 are hollow rollers, each of which has a heater 2 inside.
8 and 29 are configured to be driven to rotate and to simultaneously transfer the transfer material 2.

That is, the transfer material 2 holding the toner image is transported by the fixing roller 26 and the pressure roller 27, and the toner is fixed to the transfer material 2 by applying heat and pressure.

[Attaching of Black Developing Unit] A method of attaching the black developing unit to the apparatus body and positioning the black developing unit will be described with reference to FIGS.

FIG. 2 is a perspective view showing a state where the black developing device 21B is mounted on the guide member 50 as a guide member and is in contact with the image carrier. FIG. 3 is a front view at that time. FIG. 4 is a schematic perspective view of a position where the black developing device 21B is retracted from the image carrier in a state where the black developing device 21B is mounted on the guide member 50. FIG. 5 shows a front view at that time. FIG. 6 shows that the black developing device 21B is
It is a schematic perspective view showing the state removed from 0. FIG. 7 shows a front view at that time. FIG. 8 is a perspective view showing the appearance of the black developing device.

In the apparatus main body, a guide member 50 as a guide member for mounting the black developing device 21B is swingably disposed on both side walls 60F and 60R. The guide member 50 includes a guide arm front 50F and a guide arm back 50, one end of which is swingably supported along the side walls 60F and 60R.
R and a guide rail 50G for connecting the two.

A rotary lever 51 is arranged on the front of the apparatus main body. Cams 52 are mounted coaxially on both ends of the rotation lever shaft 53 of the rotation lever 51, and rotate in the same phase as the rotation angle of the rotation lever 51. The cam 52 is disposed so as to contact the abdomen of each of the front 50F of the guide arm and the rear 50R of the guide arm, and the rotation of the cam 52 causes the front 50F of the guide arm and the rear 50R of the guide arm to swing. The entire guide member 50 including the guide rail 50G also swings.

On the other hand, guide ribs 21BD are formed on both sides of the upper portion of the black developing unit 21B, and can be engaged with the guide rail 50G. A positioning rib 21BF is provided on the back side of the black developing device 21B, and a positioning boss 21BG is provided on the front side.

1. Insertion of Black Developing Unit When the black developing unit 21B is inserted into the apparatus main body, the rotating lever 51 is rotated and the posture is set to the horizontal position. At this time, as shown in FIGS.
The black developing unit insertion opening 54 formed in the side wall 60F on the front of the main body is entirely open.

The user supports the black developing device 21B horizontally and inserts it into the black developing device insertion opening 54. At this time, the guide rib 21BD of the black developing device 21B is inserted into the guide rail entrance 50H of the guide rail 50G.

2. When the black developing device 21B is completely pushed to reach the rear side wall 60R, the black developing device 21B is inserted into the positioning hole 50RH formed in the guide arm rear 50R.
The positioning boss 21BG is fitted. On the other hand, the positioning rib BF of the black developing device 21B is also
With the inlet 50H. Thereby, the black developing device 21B is integrated with the guide member 50 and is positioned at a predetermined position.

By the way, a CRG regulating spring 50B is arranged behind the guide rail 50G. And
The CRG regulating spring 50 is also provided on the back side of the black developing device 21B.
A groove (not shown) to be engaged with B is formed. When the black developing device 21B is pushed in all the way, the CRG regulating spring 50B enters the groove, and the black developing device 21B
Is set to the normal position. Also,
The CRG regulating spring 50B rotates the rotating lever 51,
When the black developing device 21B and the guide member 50 swing, the black developing device 21B is also prevented from shifting toward the front.

3. Setting the Black Developing Unit to the Developing Position When the rotating lever 51 is rotated clockwise in the drawing in the state of the above 2, the cam 52 is rotated, and the guide arms 50F, 50
R swings together with the guide rail 50G, and the black developing device 21B swings integrally with the guide member 50 and rotates downward. At this time, gap rollers (not shown) arranged coaxially at both ends of the developing sleeve 21BS contact the image carrier 15.

Since the diameter of the gap roller is slightly larger than that of the developing sleeve 21BS, a slight gap is secured between the developing sleeve 21BS and the image carrier 15.

As described above, since the black developing device 21B and the guide member 50 swing together, the image carrier 1
5 enables accurate positioning.

By the way, when the black developing device 21B is set at the developing position, as shown in FIGS.
The attitude of the rotary lever 51 is vertical, and a part of the black developing device insertion opening 54 is closed. Therefore,
In this state, even if the user attempts to pull out the black developing device 21B, the black developing device 21B hits the rotating lever 51 and cannot be pulled out.

That is, when taking out the black developing device 21B from the apparatus main body, the rotating lever 51 must be rotated to be in a horizontal posture. Only when the developing sleeve is retracted from the image carrier, the black developing device 21B can be moved in and out of the apparatus main body, thereby preventing damage due to the contact between the developing sleeve and the image carrier when the black developing device is attached and detached. be able to.

As described above, in this embodiment, the black developing device is supported by the guide member having the guide rail and the guide arm so as to be swingable in a direction perpendicular to the generatrix of the image carrier, and the generatrix of the image carrier is supported. , The operability is good, accurate positioning is possible, and good image formation can be performed.

Although the present embodiment has been described by taking a color image forming apparatus as an example, it goes without saying that the same effect can be obtained even if the present invention is implemented in a monochrome image forming apparatus. .

[0088]

As is apparent from the above description, the image forming apparatus according to the present invention has a guide member which is supported on the apparatus main body so as to be swingable in a direction perpendicular to the generatrix of the image carrier. The member has a guide portion for mounting the black developing device in the same direction as the generatrix of the image carrier, so that the following operation and effect can be obtained. (1) Since the black developing device can be smoothly mounted in the apparatus main body, the user interface is excellent. (2) Since the black developing device moves integrally with the guide member, accurate positioning with respect to the image carrier can be performed, and a stable and good image can be output.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a color laser printer that is an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is a perspective view showing the apparatus main body when the black developing device is mounted on a guide member and comes into contact with an image carrier.

FIG. 3 is a front view showing the apparatus main body of FIG. 2;

FIG. 4 is a perspective view showing the apparatus main body when the black developing device is mounted on a guide member and retracted from an image carrier.

FIG. 5 is a front view showing the apparatus main body of FIG. 4;

FIG. 6 is a perspective view showing a state where the black developing device is removed from the apparatus main body.

FIG. 7 is a front view showing the apparatus main body of FIG. 6;

FIG. 8 is a perspective view showing one embodiment of a black developing device.

FIG. 9 is a configuration diagram illustrating an example of a conventional color laser printer.

[Explanation of symbols]

 15 Image Carrier 20C Cyan Developing Device 20M Magenta Developing Device 20Y Yellow Developing Device 21B Black Developing Device 50 Guide Member (Guiding Member) 50F Guide Arm Front (Arm) 50G Guide Rail (Guide) 50R Guide Arm Back (Arm)

Claims (8)

[Claims] 1. An image forming apparatus having at least an image carrier on which a latent image is formed, and a black developing device for developing the latent image to form a developed image, wherein a main body of the apparatus is perpendicular to a generatrix of the image carrier. An image forming apparatus comprising: a guide member swingably supported in a predetermined direction; and the guide member includes a rail for mounting the black developing device in the same direction as a generatrix of the image carrier. . 2. The guide member includes: a rail for guiding the mounting of the black developing device; and an arm for supporting the rail in a longitudinal direction. The rail or the arm includes: 2. The image forming apparatus according to claim 1, wherein a positioning portion of the black developing device is formed, and one end of the arm portion is swingably supported in a direction perpendicular to a generatrix of the image carrier. apparatus. 3. The image forming apparatus according to claim 1, wherein the black developing device and the guide member swing integrally, and a part of the black developing device is moved from a first position at which the black developing device can contact the image carrier. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is movably supported between the retracted second position. 4. A rotatable lever is disposed on the front side of the apparatus main body, and a part of the black developing device is abutted and retracted between the first position and the second position in conjunction with the rotation of the lever. The image forming apparatus according to claim 3, wherein the lever is operated, and in the second position, the lever is disposed at a position that closes an insertion opening of the black developing device provided in the apparatus main body. 5. An image forming apparatus comprising at least an image carrier on which a latent image is formed, a black developing device for developing the latent image to form a developed image, and a developing rotary in which a plurality of color developing devices are arranged. An apparatus main body having a guide member swingably supported in a direction perpendicular to the generatrix of the image carrier, and the guide member mounts the black developing device in the same direction as the generatrix of the image carrier. An image forming apparatus having a rail portion. 6. The guide member includes a rail for guiding the mounting of the black developing device, and an arm for supporting the rail in the longitudinal direction. The rail or the arm includes: 6. The image forming apparatus according to claim 5, wherein a positioning portion of the black developing device is formed, and one end of the arm portion is supported so as to swing in a direction perpendicular to a generatrix of the image carrier. apparatus. 7. The black developing device and the guide member swing together, and a part of the black developing device is moved from a first position where the black developing device can abut on the image carrier. The image forming apparatus according to claim 5, wherein the image forming apparatus is movably supported between the retracted second position. 8. A rotatable lever is disposed on the front side of the apparatus main body, and a part of the black developing device is brought into contact with and retracted between the first position and the second position in conjunction with the rotation of the lever. 8. The image forming apparatus according to claim 7, wherein the lever is disposed at a position where the lever closes an insertion opening of the black developing device provided in the apparatus main body in the second position.