JPH10260565A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the cartridge replacing work to be smoothly performed, in a state of turning off every electric power source at the time of replacing the developing cartridge in an image forming device of a rotary system adopting the cartridge. SOLUTION: As to this device, in replacing the developing cartridge 20Y, on inputting instruction therefor, a developing rotary 23 is automatically rotated up to a specified position, and the developing rotary 23 is locked by a mechanical stopper 60 worked by a brake type solenoid 59 whose driving source is worked by a keep type solenoid 59. Even if the every power source becomes in the state of being turned off by such as an open door thereafter, the lock state is maintained, and the smooth cartridge replacing work can be performed. Moreover, the releasing work of the stopper is performed without fail in the case such as before the initial sequence begins, therefore the developing rotary 23 is surely rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus for forming an image on a recording medium using an electrophotographic technique such as a copying machine or a printer.

[0002]

The present invention is a further development of the prior art described below.

[0003] The present invention relates to an electrophotographic image forming apparatus having a rotary developing device, wherein when a developing cartridge is exchanged, the developing rotary is rotated to a replacement position and stopped. It is an object of the present invention to provide an electrophotographic image forming apparatus in which the developing rotary is fixed irrespective of whether the power supply is on or off, thereby improving the operability of exchanging the developing cartridge.

[0004]

According to a first aspect of the present invention, a plurality of developing cartridges can be attached and detached, and a mounting portion of the developing cartridge is disposed around one axis in a circumferential direction to perform development. In an electrophotographic image forming apparatus having a developing rotary in which any one of the developing cartridges is indexed and rotated to a position opposed to the electrophotographic photosensitive drum, when the developing cartridge is replaced, an instruction is input to the machine. An interface, a driving unit for rotating the developing rotary to a position where the developing cartridge is exchanged when an instruction for replacing the developing cartridge is input to the interface, and an electric driving of the developing rotary which has been rotated to the position for exchanging the developing cartridge. A fixed state having a power source and maintaining a fixed state irrespective of a power failure to the drive source. And holding means, an electrophotographic image forming apparatus characterized by having a.

A second invention according to the present application is characterized in that the driving means for rotating the developing rotary to a position where the developing cartridge is replaced also serves as the same driving means for rotating the developing rotary during the process operation. An electrophotographic image forming apparatus according to the first aspect.

According to a third aspect of the present invention, there is provided an opening for replacing a developing cartridge, a door for opening and closing the opening, energization of a driving source of the developing rotary and a driving source of a fixed holding unit of the developing rotary. A switch that turns off the power when the door is open and turns on when the door is closed.
Alternatively, an electrophotographic image forming apparatus according to the second aspect is provided.

According to a fourth aspect of the present invention, there is provided a method for controlling an electric potential before adjusting an electric potential before performing an image forming operation.
Also, in order to replace the developing cartridge, a replacement command is input to the interface, and after the sequence is completed, a developing cartridge replacement command is input again to the interface. The electrophotographic image forming apparatus according to any one of the first to third inventions, further comprising a control device for performing an operation for canceling the image.

A fifth invention according to the present application is characterized in that the drive source of the fixed state holding means is a keep type solenoid which holds the unlocked state when the fixed state is released. An electrophotographic image forming apparatus according to any one of the above.

According to a sixth aspect of the present invention, the fixed holding state holding means includes a radial slit provided on an outer periphery of the developing rotary, a projection-like stopper which is fitted into and out of the slit, and the projection A drive transmission member interposed between the drive source of the stopper and a drive member, and a spring member for urging the protrusion-shaped stopper in a direction to be fitted into the slit. Alternatively, an electrophotographic image forming apparatus according to a fourth aspect is provided.

A seventh invention according to the present application is directed to an annular outer peripheral member provided as a frame of the developing rotary, a developing rotary position detecting means provided on the outer peripheral member, and a slit provided on the outer peripheral member. The electrophotographic image forming apparatus according to the sixth aspect, wherein the slit is provided on the same member as the rotation position detecting means of the developing rotary.

An eighth invention according to the present application is characterized in that the outer peripheral member of the developing rotary provided with the slit and the developing rotary position detecting means is a member to which driving is transmitted from driving means. An electrophotographic image forming apparatus according to the invention.

According to a ninth aspect of the present invention, the driving means includes a motor, a gear provided on an outer peripheral member of the developing rotary, and a gear member connecting the motor and the developing rotary gear. An electrophotographic image forming apparatus according to an eighth aspect of the present invention.

According to a tenth aspect of the present invention, the drive transmission member has a bell crank shape pivotally mounted near an outer periphery of a developing rotary, having the stopper at one end, and having the other end connected to a movable rod of a solenoid. Sixth to ninth features
An electrophotographic image forming apparatus according to any one of the above aspects.

According to an eleventh aspect of the present invention, the stopper is biased toward the slit rather than a holding force for holding the stopper apart from the slit of the developing rotary when the keep solenoid is not energized. An electrophotographic image forming apparatus according to the tenth aspect, further comprising an urging means having a large force.

A twelfth invention according to the present application is the electrophotographic image forming apparatus according to the eleventh invention, wherein the urging means is a spring for urging the drive transmission member.

[0016]

2. Description of the Related Art A rotary type using a conventional developing cartridge is provided with an interface for inputting an instruction when the developing cartridge is exchanged. When an instruction is input to the interface, the developing rotary automatically changes the cartridge. There is known an electrophotographic image forming apparatus which rotates to a predetermined position for performing the following.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the description of the present embodiment, the longitudinal direction refers to a direction perpendicular to the transfer direction of the transfer material (recording medium) and parallel to the transfer material.

[Overall Description of Electrophotographic Image Forming Apparatus] First, the overall configuration of a color electrophotographic image forming apparatus will be schematically described with reference to FIG.

FIG. 1 is an explanatory view of the overall configuration of a laser printer which is an embodiment of a color electrophotographic image forming apparatus.

As shown in FIG. 1, a color laser printer is a photosensitive drum 1 serving as an image carrier which rotates at a constant speed.
5 and three color developing devices 20Y and 20 rotatable indexably with respect to the black developing device 21B and the photosensitive drum 15.
M and 20C, and an intermediate transfer member 9 for holding a color image developed and multiplex-transferred in the image forming unit and further transferring the color image to the transfer material 2 fed from the feeding unit.
The transfer material 2 on which the color image has been transferred is then conveyed to the fixing unit 25 to fix the color image on the transfer material 2, and discharged to discharge units 37 on the upper surface of the apparatus main body 18 by discharge rollers 34, 35 and 36. is there. Incidentally, the index developing rotatable color developing units 20Y, 20M, 20C and the fixed black developing unit 21B are configured to be individually detachable from the electrophotographic image forming apparatus main body 18.

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

[Process Cartridge] The process cartridge 13 integrally includes a photosensitive drum 15, a cleaning blade 16, a primary charging unit 17, and a cleaning container 14 also serving as a holder for the photosensitive drum 15. The cartridge is detachably supported on the main body 18 of the electrophotographic image forming apparatus, and is configured such that each cartridge can be easily replaced according to the life of the photosensitive drum 15. The photoconductor drum 15 according to the present embodiment is configured by applying an organic photoconductor layer to the outside of an aluminum cylinder, and is rotatably supported by a cleaning container 14 also serving as a holder for the photoconductor drum 15. The photoconductor drum 1 in the cleaning container 14
A cleaning blade 16 and a primary charging unit 17 are arranged on the periphery of the photosensitive drum 5, and the photosensitive drum 15 is partially exposed outside the cleaning container 14. In addition, by transmitting the driving force of a drive motor (not shown) to one end in the axial direction of the illustrated photosensitive drum 15, the photosensitive drum 15 is rotated counterclockwise in the figure in accordance with an image forming operation. .

The charging means 17 provided in the process cartridge 13 employs a contact charging method, in which a conductive roller is brought into contact with the photosensitive drum 15, and a voltage is applied to the conductive roller to thereby charge the photosensitive drum. 15 is to uniformly charge the back surface.

The process cartridge is a cartridge in which a charging unit, a cleaning unit, and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is detachable from an electrophotographic image forming apparatus main body. In addition, at least one of the charging means and the cleaning means and the electrophotographic photosensitive member are integrally formed into a cartridge so that the cartridge can be attached to and detached from the electrophotographic image forming apparatus main body.

[Exposure Means] Exposure to the photosensitive drum 15 is performed from the scanner unit 30. That is, when an image signal is given to the laser diode, the laser diode irradiates the polygon mirror 31 with image light corresponding to the image signal. 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 exposes the surface of the photosensitive drum 15 rotating at a constant speed via the imaging lens 32 and the reflection mirror 33. As a result, an electrostatic latent image is formed on the photosensitive drum 15.

[Developing Means] The developing means 20 and 21 are three developing devices 2 for developing each color of yellow, magenta, cyan and black in order to visualize the electrostatic latent image.
0Y, 20M, 20C and one black developing unit 21B. The developing means 20 will be described in more detail later.

The black developing device 21B of the developing means 21 is a fixed developing device, and a developing roller 21BS as a developer carrier is disposed at a position facing the photosensitive drum 15 at a small interval from the photosensitive drum 15. A toner image is formed on the drum 15 using black toner.

The black developing device 21B feeds the toner in the container by a feed mechanism, and applies a thin layer of toner to the outer periphery of the developing roller 21BS which rotates clockwise in FIG. 1 by an application blade 21BB pressed against the outer periphery of the developing roller 21BS. And charge is applied to the toner (frictional charging).
Further, by applying a developing bias to the developing roller 21BS, toner is supplied to the photosensitive drum 15 to perform toner development corresponding to the electrostatic latent image on the photosensitive drum 15.

[Sheet Feeding Section] The sheet feeding section transfers the transfer material 2 to the image forming section.
And a feed roller 3, a feed roller 4, a retard roller 5 for preventing double feed, a paper feed guide 6, and a registration roller 8. It is composed of During image formation, the paper feed roller 3 is driven and rotated in accordance with the image forming operation, separates and feeds the transfer material 2 in the paper feed cassette 1 one by one, and is guided by the paper feed guide 6 via the transport roller 7. To the registration roller 8. During the image forming operation, the registration roller 8 performs a non-rotating operation of stopping the transfer material 2 in a standby state and a rotating operation of transporting the transfer material 2 toward the intermediate transfer body 9 in a predetermined sequence, which is the next step. During the transfer step, the image and the transfer material 2 are aligned.

[Transfer Section] The transfer section comprises a swingable transfer roller 10.

The transfer roller 10 has a metal shaft wound around a medium-resistance foamed elastic body, is movable up and down in the figure, and rotates by receiving a driving force. While forming the four-color toner image on the intermediate transfer member 9, that is, while the intermediate transfer member 9 rotates a plurality of times, the transfer roller 10 is positioned downward as shown by a solid line in the drawing so as not to disturb the image. And is separated from the intermediate transfer member 9. After the four color toner images have been formed on the intermediate transfer member 9, the transfer roller 10 is moved by a cam member (not shown) to an upper position indicated by a thin line in the drawing, that is, the transfer, It is pressed against the intermediate transfer body 9 via the material 2 with a predetermined pressure. At this time, a bias is applied to the transfer roller 10 at the same time, and the toner image on the intermediate transfer body 9 is transferred to the transfer material 2. Here, the intermediate transfer member 9
Since the transfer material 2 and the transfer roller 10 are driven respectively, the transfer material 2 sandwiched between them is conveyed at a predetermined speed to the left in the drawing at the same time as the transfer process is performed, and is transferred to the fixing unit 25 which is the next process. Sent to.

[Fixing Section] The fixing section 25 is provided with the developing means 2
The toner image formed on the transfer material 2 is fixed on the transfer material 2 via the intermediate transfer member 9 with the toner image formed by the transfer media 0 and 21. As shown in FIG. A roller 26 and a pressure roller 27 for pressing the transfer material 2 against the fixing roller 26. Each roller is a hollow roller and has heaters 28 and 29 inside.
And is 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 conveyed by the fixing rollers 26 and 27 and heat and pressure are applied to fix the toner to the transfer material 2.

[Image Forming Operation] Next, the operation in the case where an image is formed by the above-configured apparatus will be described with reference to FIG.

First, the paper feed roller 3 shown in FIG. 1 is rotated to separate one transfer material 2 in the paper feed cassette 1, and is conveyed to the registration roller 8.

On the other hand, the photosensitive drum 15 and the intermediate transfer member 9 are driven and rotated at the same outer peripheral speed in the direction of the arrow shown in the figure.

The developing means 20 comprises three developing units 20Y and 20
M and 20C are each detachably held by a developing rotary 23 that rotates about a central axis 22. At the time of image formation, each developing device is rotated around the central axis 22 while being held by the developing rotary 23. , A predetermined developing device is stopped at a position facing the photosensitive drum 15, and further, a developing roller 20YS (not shown in the drawing, the developing device 2
(Development rollers 20MS, 20CS of 0M and 20C, respectively)
Is a minute distance (about 30 μm) from the photosensitive drum 15
After that, a visible image is formed corresponding to the electrostatic latent image on the photosensitive drum 15. At the time of forming a color image, the developing rotary 23 rotates every rotation of the intermediate transfer body 9, and a developing process is performed in the order of a yellow developing device 20Y, a magenta developing device 20M, a cyan developing device 20C, and then a black developing device 21B.

FIG. 1 shows a state in which the yellow developing unit 20Y is positioned at a position facing the process cartridge 13 and is stationary. The yellow developing device 20Y sends the toner in the container to the coating roller 20YR by a feeding mechanism, and the developing blade 20 pressed against the outer circumference of the coating roller 20YR and the developing roller 20YS rotating clockwise.
A thin layer of toner is applied to the outer periphery of the developing roller 20YS rotated clockwise by YB, and a charge is applied to the toner (frictional charging). Photoconductor drum 15 on which latent image is formed
By applying a developing bias to the developing roller 20YS opposite to the developing roller 20, the toner is developed on the photosensitive drum 15 in accordance with the latent image. In the magenta developing device 20M and the cyan developing device 20C, toner development is performed by the same mechanism as described above.

The developing rollers of the developing units 20Y, 20M and 20C are used for developing the respective colors provided on the main body 18 of the electrophotographic image forming apparatus when the developing units 20Y, 20M and 20C are indexed to the developing positions and moved. The driving member is connected to a high-voltage power supply and a drive, and a voltage is sequentially and selectively applied for each color development.

[Intermediate Transfer Body] In the intermediate transfer body 9, during the color image forming operation, the toner image on the photosensitive drum 15 visualized by the developing units 20Y, 20M and 20C is printed four times (yellow Y, magenta M and cyan C). , Each image of four colors of black B).
5 rotates clockwise in the figure in synchronization with the outer peripheral speed of the transfer member 5, and the intermediate transfer member 9 that has received the multiple transfer sandwiches the transfer material 2 with the transfer roller 10 to which a voltage is applied and conveys the intermediate transfer member 2 to the transfer material 2 Each color toner image on the transfer body 9 is simultaneously multiplex-transferred.

The intermediate transfer member 9 according to the first embodiment has a structure in which the outer periphery of an aluminum cylinder 12 is covered with an elastic layer 11 such as a medium resistance sponge or medium resistance rubber. The intermediate transfer body 9 receives a driving force from a gear (not shown) which is rotatably supported and integrally fixed, and rotates.

[Cleaning Means] The cleaning blade 16 is integrated with the above-described process cartridge 13 so as to be in pressure contact with the generatrix of the photosensitive drum 15, and the toner visualized on the photosensitive drum 15 by the developing means is removed. After being transferred to the intermediate transfer member 9, the toner remaining on the photosensitive drum 15 is scraped off and cleaned.
4 The amount of waste toner stored in the container 14 does not fill the container 14 earlier than the life of the photosensitive drum 15, and therefore, the cleaning container 14 is simultaneously replaced when the life of the photosensitive drum 15 is replaced. .

When an arbitrary point on the outer periphery of the illustrated intermediate transfer member 9 reaches the position S in the figure, the photosensitive drum 15 whose surface is uniformly charged by the charging means 17 is subjected to laser exposure at the position E in the figure, Perform formation. The distance from the exposure position E of the photoconductor drum 15 to the first transfer position T1, which is a contact portion with the intermediate transfer member 9 counterclockwise, and the distance from the illustrated S point of the intermediate transfer member 9 to the first transfer position T1 are: After the lapse of time, the point E at the start of writing the image and the point S on the intermediate transfer member 9 are equal.
At the first transfer position T1. That is, on the photosensitive drum 15, an image is formed counterclockwise with respect to the intermediate transfer body 9 starting at the point S.

1: Formation of Yellow Image Laser irradiation of the yellow image is performed by the scanner unit 30 to form a yellow latent image on the photosensitive drum 15.
Simultaneously with the formation of the latent image, the yellow developing device 20Y is driven to apply a voltage having the same polarity and substantially the same potential as the charging polarity of the photoconductor drum 15 so that yellow toner adheres to the latent image on the photoconductor drum 15, and the yellow image is formed. Perform development. At the same time, the yellow toner image on the photosensitive drum 15 is primarily transferred to the outer periphery of the intermediate transfer member 9 at a first transfer position T1 slightly downstream of the developing section. At this time, a voltage having a polarity opposite to that of the yellow toner is applied to the intermediate transfer member 9 to perform primary transfer.

When the image to be formed is, for example, A3 size of Japanese Industrial Standard paper, L1 from the outer peripheral point S of the intermediate transfer member 9
When the transfer of the yellow toner to the intermediate transfer member 9 is completed, that is, the point L1 is at the first transfer position T1. , The developing rotary 23 rotates clockwise, and the next magenta developing device 20M rotates and is positioned at a position facing the photosensitive drum 15.

2: Formation of Magenta Image Next, when one point on the outer periphery of the intermediate transfer member 9 (the leading end of the yellow image) makes a circuit and reaches the position of the point S in the drawing, the scanner unit 30 similarly irradiates the magenta image with laser. The magenta toner image is developed on the latent image on the photoconductor drum 15 in the same manner as in the case of yellow, and the magenta toner image on the photoconductor drum 15 is similarly transferred onto the intermediate transfer body 9 at the first transfer position T1. When the transfer of the magenta toner to the intermediate transfer member 9 is completed, that is, when L1 has passed the first transfer position T1, the developing rotary 23 rotates clockwise, and the next cyan developing device 20C rotates, and the photosensitive drum 15 It is positioned at a position facing.

3: Formation of Cyan Image Next, when one point on the outer periphery of the intermediate transfer body 9 (the leading end of the yellow and magenta images) makes a further round and reaches the position of the point S in the drawing, the scanner unit 30 similarly forms the cyan image. Laser irradiation is performed, and the photosensitive drum 15
A cyan toner image is developed on the upper latent image, and the photosensitive drum 1
5 is transferred onto the intermediate transfer member 9 at the first transfer position T1 so as to overlap the yellow and magenta toner images. When the transfer of the cyan toner to the intermediate transfer member 9 is completed, that is, when the point L1 has passed the first transfer position T1, the developing rotary 23 rotates clockwise by 60 degrees and the photosensitive drum 1
5, the color developing units 20Y, 20B, 2
There is no 0C.

4: Formation of Black Image Next, when one point on the outer periphery of the intermediate transfer member 9 (the leading end of the yellow / magenta / cyan image) makes another round to reach the position shown in S in FIG. Laser irradiation is performed, and then black toner is developed by the black developing device 21B, and the black toner on the photoconductor drum 15 is further transferred onto the intermediate transfer body 9 at the first transfer position T1.

As described above, the latent image formation, development and toner transfer to the intermediate transfer member 9 are sequentially performed four times in the order of yellow, magenta, cyan, and black.
A full-color image composed of four types of toner, magenta, cyan, and black, is formed.

Before the transfer of the black toner image onto the intermediate transfer member 9 is completed, that is, the image transfer point S of the intermediate transfer member 9 on which the first transfer of the black toner image is completed and the full-color image is formed is the second transfer. Before reaching the section T2, the transfer material 2 that has been waiting by the above-described registration roller 8 is started to be conveyed at a proper timing. At the time of forming each color image on the intermediate transfer body 9 for the four times, the transfer roller 10 which waits downward and is in a non-contact state with the intermediate transfer body 9 is simultaneously moved upward by a cam (not shown) to move the transfer material 2. The full-color image on the intermediate transfer member 9 is simultaneously transferred to the transfer material 2 at a stretch by applying a bias having a polarity opposite to that of the toner to the transfer roller 10 at the same time as pressing the intermediate transfer member 9 at the second transfer portion T2. The transfer material 2 that has passed through the second transfer portion T2 is separated from the intermediate transfer member 9 and is conveyed to the fixing portion 25 to fix the toner. Then, the toner is fixed to the upper portion of the electrophotographic image forming apparatus main body 18 via the discharge roller pairs 34, 35, 36. The image is discharged onto the discharge unit 37 with the image surface facing downward, and the image forming operation ends.

[Replacement of Developing Cartridge] Each of the developing units 20Y, 20M, and 20C is configured such that the toner container, the coating roller, the coating blade, and the developing roller are integrally formed into a cartridge and can be attached to and detached from the developing rotary 23. Hereinafter, the developing device will be referred to as developing cartridges 20Y, 20B,
20C.

Next, the replacement direction of the developing cartridges 20Y, 20M, 20C mounted on the developing rotary 23 will be described.

FIG. 3 is an external view of an image forming apparatus main body used in the description of the present embodiment. Image forming apparatus main body 1
A front door 51 is attached to the hinge 8 so as to be openable and closable by a hinge 51a having a vertical axis as a pivot. The front door 51 can be opened and closed in the direction of arrow α in the figure. The front door 51 is opened for jam (paper jam) processing, replacement of consumable parts, and the like.
When replacing 20M and 20C, the front door 51
Open and perform. Further, by opening the front door 51, a motor 58 to be described later that drives the developing rotary 23, a power supply to be supplied to a drive source of a fixed holding unit that makes the developing rotary 23 to be described later stationary, and a control system 5
All power supplies except the V power supply are turned off. Therefore, even if an operation such as a jam clearance is performed in this state, there is no danger that the image forming apparatus main body 18 is operated and the operator is injured.

When the front door 51 is opened, a small lid 53 for opening and closing the developing cartridge replacement port 54 and a rotary rotary button 55 as an interface for inputting a command for replacing the developing cartridges 20Y, 20B, 20C are provided therein. Exists. The small lid 53 is attached by a hinge (not shown) having a pivot along the lower edge of the developing cartridge exchange port 54, and can be opened and closed in the direction β in the drawing. When the small lid 53 is opened, the developing cartridges 20Y, 20B, 2
An exchange port 54, which is an opening for exchanging OC, appears outside.

Further, the small lid 53 is interlocked with an interlock switch (not shown) in the mechanical inside, and
Is opened, the motor 58 for driving the developing rotary 23 is opened.
(See FIG. 4), the power supply to the solenoid 59, which is the drive source of the actuator 60, is also turned off. For this reason, the developing rotary 23 does not accidentally turn around with the small lid 53 open.

Therefore, the developing cartridges 20Y, 20
Exchange of B and 20C is performed with the front door 51 opened and the small lid 53 opened. The replacement of the developing cartridges 20Y, 20M, 20C is performed by pressing the rotary rotary button 55 which is an interface for inputting a replacement command to the apparatus main body 18 in this state. When the rotary rotation button 55 is pressed, the developing rotary 23 rotates about the central axis 22 in the direction of arrow γ shown in FIG. The basic configuration of the developing rotary 23 is the central shaft 22.
A rotary stay 57 is provided radially from the boss portion 57a rotatably fitted into the boss.

An annular flange 56 is mounted on both sides of the boss 57a and the rotary stay 57 in the axial direction. FIG. 4 shows only one flange, and the other flange on the near side in the axial direction is not shown. The flange 56 has teeth cut at its outermost periphery to form a gear 56a. In the apparatus main body 18, a gear 56a, which is a large-diameter gear, meshes with a small gear 58a fixed to a motor shaft of the motor 58, and the developing rotary 23 is rotated by a driving force from the motor 58. On the back side of the flange 56, there is a flag for detecting the position (rotation direction) of the developing rotary 23. For this reason, when the developing rotary 23 rotates, the position of the flag is detected by a photo interrupter (not shown) attached to the apparatus main body 18, and the rotating position of the developing rotary 23 is controlled. Therefore, when the rotary rotation button 55 is pressed, the motor 5
With the driving force from 8, the developing rotary 23 is rotated to a predetermined position where the developing cartridges 20Y, 20M, and 20C can be exchanged while detecting the position with the flag of the flange 56. Then, at this position, the actuator 6
0 is activated, locked, and the developer cartridge can be replaced.

Developing cartridges 20Y, 20M, 20C
Can be attached to and detached from the stay 57 of the developing rotary 23 in the axial direction of the developing rotary 23.
Y, 20M and 20C are positioned and locked.

Next, the fixing and holding means of the developing rotary will be described with reference to FIGS.

FIG. 5 shows a state in which the stopper portion 60a is fitted into the slit 56A and the developing rotary 23 is locked, and FIG.
0a is a view showing a state where it is not locked because it is disengaged from the slit 56A. The position of the developing rotary 23 shown in FIGS. 5 and 6 is a position for replacing the developing cartridge 20Y. Three developing cartridges 20Y, 20M, and 20C are mounted on the developing rotary 23. In this case, the developing cartridge 20Y is replaced. The fixing and holding means of the developing rotary 23 is basically connected to a solenoid 59 fixed to the apparatus main body 18 by a pin 59 b to an iron core (movable rod) 59 a of the solenoid 59 and fixed to the apparatus main body 18. The actuator 60 includes an actuator 60 rotatably supported by the axis L and an urging means such as a torsion coil spring 61 for urging the actuator 60 in the direction of arrow δ in FIG.

The solenoid 59 is a keep-type solenoid, which can move the iron core 59a by changing the direction of energization in both directions of the arrows ε1 and ε2. Iron core 59 by a permanent magnet provided in
a is always in the state of being drawn in the direction of arrow ε1.

The actuator 60 has a bell-crank shape and has a stopper portion 60a at one end, and a long hole 60b at the other end is connected to the pin 5 at the tip of the iron core 59a of the solenoid 59.
9b, and is swingable about the fixed axis L. Therefore, the iron core 59 of the solenoid 59
If a moves in the direction of arrow ε1 in the figure, actuator 60 rotates in the direction of arrow ε1, and if iron core 59a moves in the direction of arrow ε2, actuator 60 moves in the direction of arrow δ2.

Further, as described above, the actuator 60 is provided with the torsion coil spring 61 for urging in the direction of arrow δ2. That is, the torsion coil spring 61 is inserted into the fixed shaft L, one end is locked to the fixed shaft L, and the other end is locked to the actuator 60. The force of the torsion coil spring 61 is applied to the iron core 59 of the solenoid 59.
a is pulled out. As described above, the permanent magnet is contained in the solenoid 59, and a force is constantly applied in a direction in which the iron core 59a is pulled in. However, the pulling force is one time when the iron core 59a is pulled in. In the state where the iron core 59a is pulled out, the force that is much larger than the force of the torsion coil spring 61 trying to pull out the iron core 59a is stronger. It is reversed from a certain point pulled out, and the force of the torsion coil spring 61 is applied to the solenoid 5
Thus, the iron core 59a remains pulled out. When the solenoid 59 is energized, the electromagnetic force opposes the force of the permanent magnet and is assisted by the spring force of the torsion coil spring 61, so that the iron core 59 a
When the power is supplied in the opposite polarity to the above-mentioned power supply, the iron core 59a is pulled in with the help of the force of the permanent magnet against the spring force of the torsion coil spring 61.

Since the fixing and holding means of the developing rotary 23 is as described above, an arrow ε is attached to the solenoid 59.
Normally about 200 msec so that the iron core 59a moves in the direction of 2.
c, the actuator 60 rotates in the direction of arrow δ2, and the stopper portion 60a
When the current flows for about 200 msec so that the iron core 59a moves in the direction of the arrow ε1, the actuator 60 rotates in the direction of the arrow δ1. The stopper portion 60a escapes from the slit portion 56A and is unlocked.

The flange 56 of the developing rotary 23 has
Three slits 56A, 56B, 5
6C is present. When the rotary rotary button 55 is pressed, the developing rotary 23 rotates the small gear 58a by the driving of the motor 58 and rotates the gear 56a, so that the developing rotary 23 rotates and the circumferential direction of the developing rotary 23 is evenly distributed. One of the flags (not shown) provided is detected by a photo-interrupter (not shown) fixed to the apparatus main body 18, and the developing rotary 23 is provided with slits 56A, 56B,
Either one of 56C is stopped facing the stopper portion 60a of the actuator 60, and then the solenoid 59 is moved about 200m in the direction of locking the developing rotary 23.
When the current flows for sec, and the actuator 60 rotates about the fixed axis L in the direction of arrow δ2, the stopper portion 60a at the tip of the actuator 60 is fixed in a state of being inserted into the slit 56A of the flange 56.

With the above procedure, the fixing and holding means of the developing rotary 23 moves, and the developing rotary 23 can be kept in the locked state only by turning on electricity for a moment when the solenoid 59 is moved (the state of FIG. 5). That is, when the small lid 53 is opened to replace the developing cartridge, the power of the motor 58 is also turned off. However, even in that case, the developing rotary 23 is locked, and the developing cartridge can be smoothly replaced. Further, by applying a current in the opposite direction, the fixing and holding means of the developing rotary 23 can be released. Also in this case, it is possible to keep the developing rotary 23 from being locked only by turning on the power for a moment when the solenoid 59 is moved, that is, to keep the stopper portion 60a detached from the slit 56A (the state of FIG. 6).

The releasing operation is performed before the initial sequence performed after the power is turned on or the front door is closed, etc. The developing cartridge exchange sequence is completed once and before the developing cartridge exchange sequence is started again. is there. By providing an operation to release the lock of the developing rotary at these timings, it is possible to prevent a trouble of rotating the developing rotary in a locked state. Also, when releasing, the actuator 60
The stopper portion 60a at the end of the shaft is escaped from the slit portion of the flange 56 by the suction force of the solenoid 59.

In the case of the present embodiment, the flange 56 of the developing rotary 23 has a flag for detecting the position of the developing rotary 23 in the rotation direction and the slits 56A, 56B, 56C in which the stopper 60a of the developing rotary 23 is caught.
Is provided. Since both functions are provided in the same part, the position accuracy of both the flag and the slit can be easily obtained, and the developing rotary can be locked at an accurate position. In addition, the play between the actuator and the slit can be reduced.

The flange 56 is not only for these two functions, but also for inputting a driving force from outside the developing rotary. For this reason, since a portion requiring rigidity, that is, a driving force input portion and a hook portion of the stopper portion, can be realized by one component, there is an advantage that the rigidity of one component of this component may be pursued. Furthermore, even if a certain trouble occurs and the driving force is input from the motor in the locked state, if both functions are provided in separate parts, the joint of those parts is provided. Although the occurrence of destruction and twisting of the development rotary can be considered sufficiently, by giving both functions to one rigid part such as polycarbonate with glass, breakage does not occur .

FIG. 7 is an explanatory diagram of the operation of the control device for the developing rotary described above. When the button 55 is pressed, the relay R1 is energized and the normally open contact R1-1 is closed and held, and
The normally open contact R1-2 is closed, the timer T1 is operated, and the short-time timer contacts T1-1 and T1-2 are closed and the solenoid 5 is closed.
9 operates in the direction in which the stopper portion 60a is pulled out from the slit 56A, and the stopper portion 60a is
Is pulled out, the state is maintained, and the timer contact T1-
1, T1-2 is opened. On the other hand, the timer contact T1-
1, T1-2 open at the same time as the timer contact T1-
3 is opened and the motor 58 is driven through the normally closed contact R1-3 which has already been closed, and the developing rotary 23 rotates,
When the flag interrupts the photo-inter plug 62, the timer T2 is activated by the signal, and the timer contact T2-1,
T2-2 is closed for a short time, the solenoid 59 is operated, the stopper portion 60a is fitted into the slit 56B, the timer contact T2-3 is opened, and the motor 58 stops.
It should be noted that control of such contents is all controlled by the CPU.

[0072]

As described above, according to the present invention, 1) an instruction for replacing the developing cartridge is issued to the machine main body, and after the developing rotary has been rotated to a predetermined position for replacing the developing cartridge, it is fixed and held. The developing cartridge is smoothly exchanged by engaging the means and locking the developing rotary. 2) By performing an operation of releasing the lock at a certain timing, the developing rotary can be surely rotated. 3) Since the means for detecting the position of the developing rotary in the rotation direction and the portion where the stopper portion of the fixing and holding means is present on the same member, accuracy can be improved and locking can be reliably performed. There are advantages.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a color laser printer according to the present invention.

FIG. 2 is a longitudinal sectional view of the color laser printer of the present invention, showing an image forming operation.

FIG. 3 is a perspective view illustrating an appearance of a printer used for describing the present invention.

FIG. 4 is a perspective view showing a relationship between a developing rotary and fixed holding means.

FIG. 5 is a longitudinal sectional view showing a relationship between a developing rotary and fixed holding means.

FIG. 6 is a longitudinal sectional view showing a relationship between a developing rotary and fixed holding means.

FIG. 7 is an explanatory diagram of an operation of rotating a developing rotary.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Paper feed cassette 2 ... Transfer material 3 ... Paper feed roller 4 ... Feed roller 5 ... Retard roller 6 ... Paper feed guide 7 ... Transport roller 8 ... Registration roller 9 ... Intermediate transfer body 10 ... Transfer roller 11 ... Elastic layer 12 ... Aluminum cylinder 13 ... Process cartridge 14 ... Cleaning container 15 ... Image carrier (photosensitive drum, electrophotographic photosensitive member) 16 ... Cleaning blade 17 ... Charging means 18 ... Electrophotographic image forming apparatus main body 20 ... Developing means 20Y ... Yellow developing device (Developing cartridge) 20YB: coating blade 20Y: coating roller 20YC: developing roller 20M: magenta developing device (developing cartridge) 20MS: developing roller 20C
... Cyan developing device (developing cartridge) 20CS ... Developing roller 21 ... Developing means 21B ... Black developing device 21BB ... Coating blade 21BR ... Coating roller 21BS ... Developing roller 22 ... Center shaft 23 ... Developing rotary 23A ... Stay 23B, 23
C: Developing device support 23D: Round hole 23E: Slot 25: Fixing unit 26: Fixing roller 27: Pressure roller 28: Heater 29: Heater 30: Scanner unit 31: Polygon mirror 32: Image forming lens 33: Reflecting mirror 34 ... discharge roller 35 ... discharge roller 36 ... discharge roller 37 ... discharge part 51 ... front door 51a ... hinge 53 ... small lid 54 ... developing cartridge exchange port 55 ... rotary rotary button 56 ... flange 56a ... gears 56A, 56B, 56
C: Stopper slit 57: Rotary stay 57a: Boss 58: Motor 58a: Small gear 59: Solenoid 59a: Iron core 60: Actuator 60a: Stopper 61: Torsion coil spring L: Fixed shaft

Claims (12)

[Claims] 1. An electrophotographic photosensitive drum, wherein a plurality of developing cartridges are detachably mountable, and a mounting portion of the developing cartridge is disposed around a single axis in a circumferential direction. An electrophotographic image forming apparatus having a developing rotary which is indexed and rotated to a position opposite to the interface, an interface for inputting a command to the machine when a developing cartridge is replaced, and a developing cartridge replacement command is input to the interface. Then, a driving unit for rotating the developing rotary to a position at which the developing cartridge is replaced is provided, and the developing rotary rotated to a position at which the developing cartridge is replaced is provided with an electric driving source, and fixed to the driving source. Fixed state holding means for holding the fixed state regardless of the power cutoff Electrophotographic image forming apparatus. 2. The electronic device according to claim 1, wherein the driving unit that rotates the developing rotary to a position where the developing cartridge is replaced also serves as the same driving unit that rotates the developing rotary during a process operation. Photographic image forming device. An opening for exchanging a developing cartridge; a door for opening and closing the opening; and a switch for energizing and de-energizing a drive source of the developing rotary and a driving source of a fixed holding unit of the developing rotary. 3. The electrophotographic image forming apparatus according to claim 1, further comprising: a switch that is turned off when the door is open and turned on when the door is closed. 4. An instruction to perform an exchange is input to an interface before an initial sequence for performing potential adjustment or the like before performing image formation, and to exchange a developing cartridge. The control device according to any one of claims 1 to 3, further comprising a control device that inputs an exchange command to the interface and performs an operation of releasing the fixed state of the fixed holding unit before the sequence starts. Electrophotographic image forming apparatus. 5. The electronic device according to claim 1, wherein the drive source of the fixed state holding means is a keep type solenoid that holds the released state when the fixed state is released. Photographic image forming device. 6. The fixed holding state holding means includes: a radial slit provided on an outer periphery of a developing rotary; a protruding stopper that fits in and out of the slit; and a driving source for the protruding stopper. 5. The electronic device according to claim 1, further comprising: a drive transmission member interposed therebetween; the drive source; and a spring member for urging the protrusion-shaped stopper in a direction to be fitted into the slit. Photographic image forming device. 7. An annular outer peripheral member provided as a frame of the developing rotary, a rotation position detecting means of the developing rotary provided on the outer peripheral member, and the slit provided on the outer peripheral member, 7. The electrophotographic image forming apparatus according to claim 6, wherein the rotation position detecting means of the developing rotary and the slit are provided on the same member. 8. The electrophotographic image according to claim 7, wherein the outer peripheral member of the developing rotary provided with the slit and the developing rotary position detecting unit is a member to which driving is transmitted from a driving unit. Forming equipment. 9. The developing device according to claim 1, wherein the driving unit includes a motor, a gear provided on an outer peripheral member of the developing rotary, and a gear member connecting the motor and the developing rotary gear. 9. The electrophotographic image forming apparatus according to 8. 10. The power transmission member according to claim 6, wherein the drive transmission member has a bell crank shape pivotally mounted near an outer periphery of the developing rotary and having the stopper at one end and the other end connected to a movable rod of a solenoid. 10. The electrophotographic image forming apparatus according to any one of items 1 to 9. 11. A biasing means having a force for biasing the stopper toward the slit is larger than a holding force for holding the stopper apart from the slit of the developing rotary when the keep solenoid is not energized. The electrophotographic image forming apparatus according to claim 10, comprising: 12. An electrophotographic image forming apparatus according to claim 11, wherein said urging means is a spring for urging said drive transmission member.