JP2000227715A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device with a constitution capable of preventing the erroneous operation by correctly making a developing unit becoming the object of replacement possible to be replaced in the developing device equipped with plural developing units with the same constitution. SOLUTION: This device is provided with an opening part 1D formed on a side wall 1C of the image forming main body, in size making one of the developing units attach/detachable, and a drive source making the developer carrier being disposed in the developing unit held out of a position facing the latent image carrier at the non-image forming time, while disposed on the position allowed to feed the developer from the developer carrier by successively making the developer carrier faced to the latent image carrier at image forming time. Then, the device is allowed to form the opening part 1D, in the similitude of an external shape of the developing unit, and the drive source is allowed to station the developing unit at the position of the opening part 1D whose port edge shape is not matching with the external shape of the developing unit at the non-image forming time, and to shift the developing unit located in the position of non-image forming time toward the position permitting to match with the shape of the opening part 1D, when replacing the developing unit.

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, and more particularly, to an image forming apparatus provided in a developing device used for visible image processing of an electrostatic latent image formed on a latent image carrier by an electrophotographic method. And a mechanism for inserting and removing the developing unit.

[0002]

2. Description of the Related Art In general, an image forming apparatus using an electrophotographic method, such as a copying machine or a printer, uses a photosensitive member constituting a latent image carrier. In electrophotography,
After the photoreceptor is uniformly charged, light is written using laser light or the like, a latent image corresponding to the original is formed, the latent image is processed with a developer, and then the visible image is transferred. An image is obtained by transferring the image to paper or the like.

In recent years, color image forming apparatuses for forming images of not only a single color but also a plurality of colors including a full color have been proposed and put into practical use. In a color image forming apparatus, a latent image is formed on a photoreceptor by reflected light obtained by performing color separation of reflected light from a document, and in a printer, irradiation images corresponding to color information form latent images. The visible image is processed with a developer of a color that is complementary to the color-separated reflected light or irradiation light, and the process of primary transferring the visible image to the intermediate transfer member is repeated. The corresponding visible images are collectively transferred to a transfer paper or the like by a secondary transfer process.

As one of the structures of a developing device used for visible image processing in a color image forming apparatus, a developing unit containing developers of different colors at regular intervals along a circumferential direction of a rotating body is arranged. There is a configuration in which each developing unit faces the photoconductor by intermittently rotating the rotator to perform visible image processing of a latent image by using developers of different colors.

The developing unit may use a one-component developer composed of only a magnetic or non-magnetic toner. In this case, the developing unit is carried on a developing sleeve arranged opposite to the photosensitive member. The one-component developer is thinned and supported by a blade or the like.

In a developing device provided in a color image forming apparatus, an image is formed by supplying a developer with one of developing units arranged side by side in a circumferential direction facing a photoreceptor. When image formation is not performed, that is, during non-image formation, the developing unit is not opposed to the photoconductor, thereby preventing the photoconductor from being stained. For this reason, the developing device is maintained in a standby state in which the developing unit does not face the photoconductor until image formation is restarted during non-image formation.

[0007]

SUMMARY OF THE INVENTION
When the contained developer is consumed, it is necessary to replenish the developer. In recent years, instead of a type in which a developer is injected into a developing unit, a type has been proposed in which the developing unit itself is inserted into and removed from the developing device to prevent the replacement work environment from deteriorating.

In order to achieve this, an opening having a size capable of taking in and out one of the developing units provided in the developing device is formed in a part of the side wall of the color image forming apparatus.
There is a configuration in which a developing unit to be replaced is located in the opening and is taken in and out. When the developing unit is replaced, it is necessary to perform the operation in a state where the developing unit does not face the photoconductor in order to avoid contact between the photoconductor and a member such as a developing sleeve in the developing unit. For this reason, when replacing the developing unit, the developing unit may be replaced at the standby state.

However, in such a configuration, the developing unit in the standby state and the developing unit to be replaced cannot be distinguished, and the developing unit facing the opening in the side wall may be pulled out. There is a possibility that a developing unit other than the developing unit to be replaced is replaced.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional image forming apparatus, it is an object of the present invention to make it possible to reliably replace a developing unit to be replaced in a developing apparatus having a plurality of developing units having the same configuration. It is an object of the present invention to provide an image forming apparatus having a configuration capable of preventing an erroneous operation from occurring.

[0011]

According to the first aspect of the present invention,
An image forming apparatus comprising: a developing device provided with a plurality of developing units each having a developing carrier used for visible image processing of a latent image formed on the latent image carrier by an electrophotographic method; An opening having a size that allows one of the developing units to be inserted into and removed from the side wall of the developing unit; A drive source for holding the developing carrier at a position not facing the body, and for sequentially forming the developing carrier toward the latent image carrier during image formation to allow supply of developer from the developer carrier; Is
The drive unit is formed to be similar to the outer shape of the developing unit, and the drive source is configured to fix the outer shape of the developing unit and the edge shape of the opening at a position where the outer shape of the developing unit does not match at the time of non-image formation, When the developing unit is replaced, the developing unit fixed at the non-image forming position is moved toward a position that matches the shape of the opening.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the driving source is driven by a control unit in which an image forming end detecting unit and a replacement instruction unit are connected to an input side. The control unit drives the drive source so that the developer carrier is stopped at a position where the developer carrier is not opposed to the latent image carrier during non-image formation. The driving source is driven so that the developing unit is moved to a position that matches the edge shape of the opening and stopped.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the replacement instruction means detects a remaining amount of the developer in the developing unit, and determines when the remaining amount reaches a predetermined amount. , A remaining amount detecting means for outputting a signal is used.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a main configuration of a color image forming apparatus which is one of the image forming apparatuses according to the present embodiment. In FIG. 1, a color image forming apparatus 1
Is provided with a photoreceptor 2 as a latent image carrier in a housing. The photoreceptor 2 is formed in a belt shape (hereinafter, referred to as a photoreceptor belt) wrapped around a pair of pulleys 2A and 2B, and moves in the direction indicated by the arrow as each pulley 2A and 2B rotates clockwise as indicated by the arrow. I do. In FIG. 2, a roller 2C disposed inside the photosensitive belt 2 is a tension roller.

Around the photoreceptor belt 2, a charging device 3, an optical writing device 4, a developing device 5, a transfer device 6, and a cleaning device 7 for performing electrophotography along the moving direction are arranged. I have. The developing device 5
Has a configuration in which a plurality of developing units accommodating developers of different colors are arranged along the circumferential direction, as will be described later, and each developing unit sequentially faces the photoreceptor belt 2. The developer is supplied. The transfer device 6 includes a transfer belt 6C that is wound around a pair of rollers 6A and 6B and moves in the same direction at a position facing the photoreceptor belt 2, and a transfer bias is applied to a position facing the photoreceptor belt 2. A bias device 6D to be set is arranged. In FIG. 1, reference numeral 6E denotes a cleaning device for removing the developer remaining on the transfer belt 6C in the transfer device 6.

In the vicinity of the transfer device 6, a batch transfer device 9 is arranged on the side of the roller 6A that is opposite to the surface facing the photoreceptor belt 2 among the expanded surfaces of the transfer belt 6C.

The batch transfer device 9 is constituted by a bias device that batch-transfers a full-color image superimposedly transferred onto the transfer belt 6C onto a recording medium such as a transfer sheet fed from the sheet feeding device 8.

The paper feeding device 8 includes a paper feeding cassette 8A for storing a recording medium such as transfer paper, a feeding roller 8B for feeding out the recording medium from the paper feeding cassette 8A, a conveying roller 8B1, and a registration roller 8B2. Have. In this embodiment, a part of the housing of the color image forming apparatus 1 (for convenience, indicated by reference numeral 1A) is provided as an openable and closable cover, and a manual paper feed tray 1B is provided therein. A conveyance path switching claw 8B3 for setting a conveyance path between the recording medium from the sheet feeding tray 8A and the recording medium from the manual sheet feeding tray 1B is provided in front of the registration roller 8B2. The route can be switched to be guided to the collective transfer device 9.

A fixing device 10 for fixing an image transferred onto a recording medium is provided behind the collective transfer device 9. The fixing device 10 includes a heating roller 10A having a built-in heater and a heating roller 10A. A pressure roller 10 </ b> B is provided in contact with and in opposition to the pressure roller 10 </ b> B.

The recording medium fixed by the fixing device 10 is discharged onto a discharge tray 12 by a discharge roller 11. In FIG. 1, reference numeral 10C denotes
Fig. 3 shows an oil application device for preventing transfer of a developer.

In the color image forming apparatus using the photoreceptor belt 2, when the electrostatic latent images of each color are processed into a visible image by the developing device 5, the visible images are sequentially transferred to the transfer belt 6 C of the transfer device 6. A full-color image is formed by superimposed transfer, and the full-color image is collectively transferred to a recording medium.

The developing device 5 includes four developing units containing yellow, magenta, cyan, and black developers having a complementary color relationship with the color separated in the circumferential direction. The unit constitutes a rotary developing device capable of supplying a developer of a color corresponding to an electrostatic latent image formed on the photosensitive belt 2 opposite the photosensitive belt 2. The developing units included in the rotary developing device 5 have the same configuration, and details thereof are shown in FIG. FIG. 2 shows that one of the developing units is a photosensitive belt 2.
In the figure, a developing unit (for the sake of convenience, a developing unit containing a yellow developer and denoted by a letter Y) 5Y is a developing unit. A configuration using a non-magnetic one-component developer is provided. That is, the developing unit 5Y is provided with the developing sleeve 5Y1 whose part of the peripheral surface is exposed from the opening formed in part of the casing. The rotation direction of the developing sleeve 5Y1 is set such that the developing sleeve 5Y1 moves in the same direction at a position facing the photosensitive belt 2 at a predetermined peripheral speed ratio. A supply roller 5Y2 for supplying the developer is in contact with the developing sleeve 5Y1. The supply roller 5Y2 is a roller made of an elastic body such as foamed polyurethane, and has a rotation direction in which the supply roller 5Y2 moves in the same direction at the contact position with a predetermined peripheral speed ratio with the developing sleeve 5Y1.

A housing space 5Y3 for housing the developer is provided in a part of the developing unit 5Y.
Between the supply roller 5Y2 and the supply roller 5Y2,
A flicker member 5Y4 that is pressed against the peripheral surface with a predetermined bite amount and a shielding member 5Y5 that is disposed between the flicker member 5Y4 and the housing space 5Y3 are provided. The flicker member 5Y4 frictionally charges the developer from the storage space 5Y3 while being carried on the surface of the supply roller 5Y2, and supplies the developer with the supply roller 5Y3.
2 is a member that regulates the amount of developer carried, and is configured to rotate in a rotation direction that moves in the same direction at a pressure contact position with the supply roller 5Y2.

The shielding member 5Y5 is a blade member that prevents the developer from flowing directly from the storage space 5Y3 toward the developing sleeve 5Y1, and transfers the developer in the storage space 5Y3 between the supply roller 5Y2 and the flicker member 5Y4. Only to be introduced. For this reason, the flicker member 5Y4
The developer is carried on the developing sleeve 5Y1 in a state where the shortage of the charge amount generated in the developer reaching the developing sleeve 5Y1 without passing through the developing sleeve 5Y1 is eliminated.

The developer in the accommodating space 5Y3 reduces the bulk density between the particles due to air entering between the particles due to inertia when the rotary developing device 5 rotates, so-called adhesive force between the particles. Has the property of increasing the fluidity by being weakened, exhibits fluidity like a liquid, and can flow out of the storage space 5Y3. For this reason, as shown in FIG. 2, when the opening of the storage space 5Y3 faces downward, that is, when the shielding member 5Y5 is located below the storage space 5Y3, the shielding member 5Y5 directs the toner to the developing sleeve 5Y1. Flow is regulated, and the developer flowing out of the storage space 5Y3 is pumped up by the rotation direction of the supply roller 5Y2. The amount of the developer drawn up by the supply roller 5Y2 is regulated by the cooperation of the supply roller 5Y2 and the flicker member 5Y4, and the required charge amount when the developer is carried on the development sleeve 5Y1 is friction. Set by charging.

The developing unit 5Y includes a developing sleeve 5Y.
A thinning blade 5Y6 is provided in contact with the peripheral surface at a position before facing the photoreceptor belt 2 in one rotation direction. The thinning blade 5Y6 is a member for regulating the developer carried on the developing sleeve 5Y1 into a thin layer having a uniform thickness, and is a thin plate having a spring property such as a stainless steel plate or an elastic material such as urethane rubber. Are supported in a cantilever shape.

In the developing unit 5Y, when the developing sleeve 5Y1 is disposed at a position facing the photoreceptor belt 2 by rotation of the developing device 5, the developer flows out of the accommodating space 5Y3 and flickers when it is pumped up by the supply roller 5Y2. The amount of toner carried on the supply roller 5Y2 is regulated by the member 5Y4, and is supplied to the developing sleeve 5Y1 after being triboelectrically charged. The developer carried on the developing sleeve 5Y1 is defined as a thin layer having a uniform thickness by the thinning blade 5Y6, and is supplied to the electrostatic latent image on the photosensitive belt 2 by contact or non-contact.

As shown in FIG. 3, each developing sleeve including the developing sleeve 5Y1 is mounted on a rotatable developing unit support member 5F provided in the image forming apparatus. The developing unit support member 5F has a length capable of accommodating the developing unit, is provided with an end plate 5F2 having an opening 5F1 into which each developing unit can be inserted, at one end in the longitudinal direction, and a rotational drive source ( A gear 5G, which is a power transmission mechanism from a motor (not shown), is provided. The end plate F2 and the gear 5G are connected by a partition wall 5F3 that divides a mounting portion of each developer unit. Although FIG. 3 shows only a developing unit for yellow developer denoted by reference numeral 5Y, each of the cyan, magenta, and black developing units (not shown) is a developing unit support member similarly to the developing unit 5Y. 5F can be inserted and removed through the opening 5F1.

As shown in FIG. 4, a motor, which is a drive source for transmitting power to the gear 5G, is controlled by a control unit, which will be described later, with respect to the photosensitive belt 2 as shown in FIG. The developing sleeves 5Y1 and 5B in FIG.
And a home position corresponding to a state in which the developing sleeve (not shown) is not opposed to the opening 1D (see FIG. 5).
The developing unit supporting member 5F is rotated so that the developing unit to be replaced can be positioned at a replacement position where the developing unit to be replaced is opposed.

In this embodiment, as shown in FIG. 4, in the rotation direction of the developing device 5 (in the direction of the arrow shown in the figure), the developing unit 5Y containing the yellow developer firstly moves the photosensitive belt 2 during image formation. When the developing device 5 is set at the home position, the developing sleeve 5Y1 of the developing unit 5Y containing the yellow developer and the rotation of the developing device 5 are set. When the developing unit 6Y is set as a starting point in the direction, the intermediate position between the developing sleeve 5B1 of the developing unit 5B and the developing sleeve 5B1 that contains the black developer is positioned so as to face the photosensitive belt 2. Therefore, the developing units 5Y facing the photoreceptor belt 2
5B, the developing sleeves 5Y1 and 5B carrying the developer
1 are maintained in a state where they do not face each other.

As shown in FIG. 5, an opening 1C for inserting and removing the developing unit of the developing device 5 is provided on the side wall of the housing forming the main body of the image forming apparatus 1. FIG.
FIG. 3 is a perspective view showing a side surface of a housing of the image forming apparatus 1, and a part of a side wall 1 </ b> C includes a developing unit, for example, the outer shape of a developing unit indicated by reference numeral 5 </ b> Y in FIG. As shown by reference numeral 5YT, an opening 1D having a shape similar to the outer shape of the developer replenishing tank provided in the developing unit 5Y is formed. The opening 1D is provided at a position that can face a developing unit (a developing unit 5C containing a cyan developer in FIG. 4) located in the fourth quadrant among the respective developing units. It is designed to be closed by a lid 1E.

As shown in FIGS. 4 and 5, the opening 1D has a lower side 1 extending in the horizontal direction among the sides forming the rim.
D1; a vertical side 1D2 extending vertically from one end of the lower side 1D1; and a curved side 1D3 connecting the lower side 1D1 and the vertical side 1D2. The forming direction of each side portion will be described later, but the shape center line L of the opening 1D is formed.
1 and the shape center line L2 on the developing unit side are changed to set a state in which the developing unit can be inserted and removed and a state in which the developing unit cannot be inserted and removed. It is set so that a state where it can be inserted and removed without facing the belt 2 is obtained.

The motor which is the driving source of the developing device 5 is shown in FIG.
The rotation is controlled by the control unit 20 shown in FIG. The main part of the control unit 20 is constituted by a microcomputer, and a mounting sensor for detecting the mounting state of the image forming completion detecting unit 21, the replacement commanding unit 22 and the developing unit on the input side via an I / O interface (not shown) 23, and a motor 24 is connected to the output side via a drive unit (not shown).

The image forming end detecting means 21 uses a counter for counting the number of images formed, that is, the number of recordings, and outputs a signal when the count value reaches "0". The unit 22 uses a remaining amount detecting unit (not shown) capable of detecting the remaining amount of the developer in the developing unit, and outputs a signal when the amount of the developer decreases below a predetermined amount. The mounting sensor 23 outputs a signal when the developing unit is mounted in the developing unit supporting member 5F (see FIG. 3).

In the control section 20, the image forming end detecting means 2
1 to control the rotation of the developing device 5 to the home position based on the signal from the control unit 1 and to position the developing unit of the developing device 5 so as to face the opening 1D based on the signal from the exchange command means 21. Rotation control. The home position of the developing device 5 is, as described above, a state in which the developing sleeve of the developing unit does not face the photoreceptor belt 2, and in this state, as shown in FIG. 4
The center line of an arc that forms the outer shape of the developer replenishment tank 5CT of the developing unit 5C that moves to the opening 1D with respect to the center L (shown by L1) (shown by L2 in FIG. 4)
Are set so that they do not match and are shifted. Therefore, as shown in FIG. 4, the outer shape of the developer replenishment tank 5CT interferes with the rim of the opening 1D, and the developing unit 5C cannot be pulled out.

In FIG. 4, the outer shape of the developing unit (denoted by reference numeral 5C for convenience) of the developing device 5 and the opening 1D are shown.
When the shape of the edge is matched, the center line (L1) of the arc of the opening 1D is made to coincide with the center line (L2) of the arc in the developer replenishment tank 5CT. In this state, the developing unit 5C can be pulled out or inserted from the opening 1D. Arc center line of opening 1D (L1)
The inclination angle is determined based on the vertical line based on the following reasons. 4, the outer shape of the developing unit 5C and the rim shape of the opening 1D coincide with each other, and when the developing unit 5C is inserted and removed from the opening 1D, the home position is set. Similarly to the above, the developing units 5Y,
A state where the developing sleeves 5Y1 and 5B1 of 5B do not contact each other is obtained. Thus, when the developing unit 5C is inserted or removed with the center lines L1 and L2 aligned with each other, the developing sleeves 5Y1 and 5B1 do not accidentally come into contact with the photosensitive belt 2 and the photosensitive member The surface of the belt 2 or the developing sleeve can be prevented from being damaged.

In the case where the signal from the exchange command means 22 is not output, the control section 20 terminates the image formation.
A state in which the developing sleeve is not opposed to the photosensitive belt 2 at a position where the developing unit is displaced from the arc center line (L1) of the opening 1D, that is, a stop position of the motor 24 so that a home position of the developing device 5 is obtained. When a signal is output from the replacement command means 22, the motor is defined by defining an angle at which the center line (L2) of the developing unit to be replaced matches the center line (L1) of the opening 1D. 24 is stopped.

Since the present embodiment has the above configuration,
The operation based on the operation of the control unit 20 will be described with reference to FIG. In FIG. 7, the control unit 20 determines the end of image formation (ST1). When the image formation is completed, it determines whether there is an exchange command (ST2).
If there is no replacement command, the amount of rotation for positioning the developing unit of the developing device 5 at the home position is set, and the motor 24 is driven and stopped (ST3).

When there is an exchange command, the following procedure is executed. Based on the replacement command, a developing unit to be replaced is selected (ST4). The selection in this case is to determine which of the developing units provided in the developing device 5 is to be replaced, and to determine the rotation amount of the developing unit to be replaced, that is, from the position at the home position, the opening 1
The amount of rotation that can face D is calculated (ST
5) The motor 24 is driven based on the rotation amount (ST6).

When the developing unit to be replaced faces the opening 1D, the center lines indicated by reference numerals L1 and L2 in FIG. 4 coincide with each other, and the outer shape of the opening 1D matches the outer shape of the developing unit. Therefore, the developing unit can be pulled out from the opening 1D and inserted again.

On the other hand, when the replacement is completed, the mounting sensor 23
It is determined whether or not the image formation has been resumed at the time when the mounting of the developing unit has been detected (ST
7) If not resumed, processing for positioning the developing device 5 at the home position is executed.

According to the present embodiment, after the replacement is completed, the developing unit can be positioned at the home position instead of being fixed at the position at the time of replacement except when resuming image formation. On the other hand, it is possible to prevent color mixture due to inadvertent adhesion of the developer, which is generated when the developing sleeves of the same color always face each other.

[0044]

According to the first to third aspects of the present invention, the developing unit at the time of replacement with the developing unit located at the so-called home position with respect to the opening formed in the side wall of the image forming apparatus main body. The position of the developing unit can be different from that of the other unit, and in particular, only the developing unit to be replaced can be inserted into and removed from the opening. Can be eliminated. In particular, according to the second and third aspects of the present invention, only the developing unit to be replaced can be located in the opening by the driving source used to make the developing unit face the latent image carrier. It is possible to reliably insert and remove only the developing unit to be replaced without requiring a simple identification structure.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a main part of an image forming apparatus according to an example for describing an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a configuration of a developing unit provided in a developing device used in the image forming apparatus shown in FIG.

FIG. 3 is a perspective view of a main part for describing a support structure of a developing unit used in the image forming apparatus shown in FIG.

4 is a schematic side view of the developing unit supported by the support structure shown in FIG.

FIG. 5 is a partial perspective view showing a side wall of the image forming apparatus shown in FIG. 1;

FIG. 6 is a block diagram illustrating a configuration of a control unit for a driving source of the developing unit.

FIG. 7 is a flowchart for explaining the operation of the control unit shown in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Color image forming apparatus which is one of image forming apparatuses 1C Side wall 1D Opening 1D1 Lower side 1D2 Vertical side 1D3 Curved side 2 Photoconductor belt which is a latent image carrier 3 Charging device 4 Optical writing device 5 Developing device 5Y, 5C, 5M, 5B Developing unit 5Y1, 5C1, 5M1, 5B1 Developing sleeve 5F Developing unit support member 20 Control unit 21 Image formation completion detecting means 22 Replacement command means 23 Mounting sensor 24 Motor serving as a drive source of the developing device

Continued on the front page F-term (reference) 2H030 AA07 BB24 BB33 2H077 AD02 AD06 BA08 BA09 DA15 DA22 DA51 DA76 DA80 EA14 EA16 GA13

Claims (3)

[Claims] An image forming apparatus provided with a developing device provided with a plurality of developing units having a developing carrier used for visible image processing of a latent image formed on the latent image carrier by an electrophotographic method. An opening formed in a side wall of the image forming main body and having a size that allows one of the developing units to be inserted thereinto, and a developer carrying member provided in the developing unit during non-image forming when image formation is not performed. And a driving source that allows the developer to be supplied from the developer carrier by sequentially facing the developer carrier to the latent image carrier during image formation. The opening is formed so as to be similar to the outer shape of the developing unit, and the driving source is located at a position where the outer shape of the developing unit does not match the edge shape of the opening during non-image formation. the above An image forming apparatus, wherein the developing unit is fixed, and when the developing unit is replaced, the developing unit fixed at the position at the time of non-image formation is moved toward a position matching the shape of the opening. . 2. The image forming apparatus according to claim 1, wherein the drive source is driven by a control unit connected to an input side of an image formation end detection unit and an exchange instruction unit, The drive source is driven so that the developer carrier is stopped at a position where the developer carrier is not opposed to the latent image carrier at the time of formation, and when a signal is input from the exchange command means, the developing unit to be exchanged is opened with the opening. An image forming apparatus that drives the driving source so as to move to a position that matches the shape of the rim and stop the driving. 3. The image forming apparatus according to claim 2, wherein said replacement command means detects a remaining amount of the developer in the developing unit, and outputs a signal when the remaining amount reaches a predetermined amount. An image forming apparatus, wherein an amount detection unit is used.