JPH08254874A - Image forming device - Google Patents

Abstract

PURPOSE: To move the requested one out of a plurality of developing units incorporated in a holding means into the position where a latent image formed on a photoreceptor can be developed by means of a simple structure by driving the holding means based on an amount of movement obtained by referring to a table. CONSTITUTION: The speed control table according to target positions-rotating speed characteristics is stored in a ROM in a motor control CPU. The speed data of the speed table in the ROM which is accessed according to a position counter value detected every fixed time by a timer is compared with speed data detected by a speed counter, and the driving force of a motor 12 is controlled so that the deviation is corrected. Thus, a rotor 4a can be controlled according to a target motion characteristic so as to be driven into a target position. In order to absorb rotational energy of the rotor 4a in a target stopping position and stop and hold it in the position, a positioning member, comprising a stopper arm and a stopper plate 18 is provided.

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 having a plurality of developing devices.

[0002]

2. Description of the Related Art As a constitution in which a developing device using a plurality of toners of different colors is arranged on a single latent image carrier such as a photosensitive drum, a plurality of developing devices are sequentially arranged on the peripheral surface of the latent image carrier. By supporting a plurality of developing devices by a rotating body with respect to the developing devices arranged side by side, and rotating the rotating body,
The applicant of the present application has proposed a multi-color developing device in which only a developing device corresponding to a desired color toner is opposed to a latent image carrier (Japanese Patent Laid-Open No. 50-93437).

[0003]

Conventionally, a holding means for integrally holding a plurality of developing devices has been provided, and by driving this holding device to move the developing devices, the latent image formed on the photosensitive member has been developed. In an image forming apparatus for developing an image, the holding means is driven so as to surely move one of the plurality of developing devices to a position where a latent image formed on a photoconductor can be developed by a simple structure. The method was not considered.

Therefore, the present invention has a holding means for integrally holding a plurality of developing devices, and the holding device is driven to move the developing devices to develop the latent image formed on the photoreceptor. In order to reliably move the desired one of the plurality of developing devices included in the holding unit to a position where the latent image formed on the photoconductor can be developed with a simple structure, The purpose is to drive the holding means.

[0005]

In order to solve the above-mentioned problems, according to the image forming apparatus of the first aspect of the present invention, a plurality of developing devices respectively containing developers of different colors are used for exposure. In an image forming apparatus that forms a color image by developing a latent image formed on a body, a holding unit that integrally holds the plurality of developing units, and a movement amount of the developing unit held by the holding unit. Based on the amount of movement obtained by referring to the storing means and the table, so that one of the plurality of developing devices comes to a position where the latent image formed on the photoconductor can be developed. And driving means for driving the holding means.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
It will be described based on.

FIG. 1 is a cross-sectional view showing an example of an electrophotographic copying machine as an image forming apparatus having a rotationally driven multicolor developing device.

In the figure, the photosensitive drum 1, which is a latent image carrier, rotates in the direction of the arrow. A charging device 2, an exposure optical system 3, a developing device 4, a transfer system 5, and a cleaning device 6 are arranged around it. The optical system 3 has a document scanning section 3a and a color separation filter section 3b. Further, the developing device 4 integrally includes a yellow developing device 4Y that uses yellow toner, a magenta developing device 4M that uses magenta toner, a cyan developing device 4C that uses cyan toner, and a black developing device 4BK that uses black toner. Each developing device is disclosed in Japanese Patent Publication No. 55-20579 by the present applicant,
The toner is prevented from scattering by the action of the magnetic field by the magnet roller R, and is detachably held by the rotating body 4a as shown in the drawing and rotates about the central shaft 4b, so that the developing device is exchanged with respect to the developing position. In addition, S is a toner stirring screw.

On the other hand, the transfer section 5 has a drum 5b having a gripper 5a and a transfer discharger 5c inside thereof.

When forming a color image, color separation is performed by the blue, green and red color filters and the ND filter of the color separation optical system, as in the conventional copying machine.
Three colors of yellow, magenta, and cyan, and further black are added, and development is performed by a four-color developing device.

Now, for example, when blue light (exposure) is applied to the photosensitive drum 1, a latent image is formed on the photosensitive drum 1,
The formed latent image is made into a visible image by the yellow developing device 4Y which is rotationally moved to the developing position at an appropriate timing, and this visible image is transferred onto the transfer paper held on the transfer drum 5b by the transfer charger 5c. To be done. This transfer paper is supplied from the cassette 7. After the above-described processes from exposure to development are performed on the photosensitive drum 1 by cleaning, the green light is performed by the magenta developing device 4M and the red light is performed by the cyan developing device 4C. Is done. Further, exposure is performed using the ND filter, and after the exposure is developed by the black developing device 4BK, transfer is performed. The transfer material which has completed the transfer step is separated by the separating means 8 and reaches the tray 10 via the fixing device 9.

In FIG. 2, reference numeral 11 denotes a ring-shaped rear side plate which is provided at the rear end portion of the rotating body 4a and has the gear 11a in the peripheral portion. Reference numeral 12 is a rotation driving motor, and a gear 13 fixed to one end of the motor shaft is connected to the gear 11a through gears 14, 15 and 16, and a rotation speed and a position are provided at the other end of the motor shaft. For example, an encoder 17 is provided as a detection unit of the. Z is a positioning means for forcibly stopping the rotating body 4a at a predetermined stop position, and a stopper plate 18 having a groove 18a and an edge 18b is attached to the rear side plate 11.

FIG. 2 shows two stopper plates partially broken, but in this embodiment, as will be described later, five stopper plates 18HP, 18Y, 18M, 18C and 18 are provided.
BK is fixed in place.

On the other hand, Z1 is a rotation holding mechanism that engages with the stopper plate 18 (see FIG. 3 for details), and 19 is L.
With a stopper arm having a character, the other end of a pin 20 whose one end is fixed to the apparatus main body is inserted into an elongated hole 19a formed in a part of the elbow. A roller 22 is rotatably attached to one end of the stopper arm 19 by a stopper pin 21, and a tension coil spring 23 is stretched between the stopper pin 21 and the pin 20. Stopper arm 1
At the other end of 9, a lock solenoid 25 as a holding release means is pivotally attached by a pin 27 via a connecting member 26, and a spring 28 causes the roller 22 to move the roller 22 to the stopper plates 18HP, 18Y, 18M, 18C, It is urged to come into contact with the periphery of 18BK. Reference numeral 29 is a photo interrupter as a detecting means for detecting the connection and the release of the rotating body 4a and the stopper arm 19, and is arranged so that the light is interrupted according to the movement of the end 24 of the stopper arm 19. There is.

X is a reference position of the rotating body 4a and a developing position detecting means. A position detection plate XI attached to the end of the central axis 4b, a home position sensor (HP sensor) OX arranged concentrically around the central axis 4b, a yellow developing position sensor XY, a magenta developing position sensor XM, a cyan developing position sensor. XC and black developing position sensor XBK are provided. Each sensor outputs a separate development position signal when the position detection plate XI is right above.

FIG. 4 shows a control system. Reference numeral 30 is a driver for driving the motor 12, and constitutes a driving means for rotating the rotating body 4a together with the motor 12. 31 is a control means for controlling the speed of this drive means,
A vector detection circuit 31a for detecting the rotation direction of the rotating body 4a, a position counter 31b for detecting the rotating position of the rotating body 4a, a speed counter 31c for detecting the rotating speed of the rotating body 4a, a position and a speed of the rotating body 4a. A CPU for controlling a motor (central processing unit)
t) 31d, home position sensor XO, timer 31
It is composed of an f / D / A converter 31g.

The vector detection circuit 31a is an encoder 17
The two-phase pulse from is input and the data regarding the forward and reverse rotation directions of the rotating body 4a are output. The position counter 31b is an up-down type counter, receives the data regarding the forward and reverse rotation directions from the vector detection circuit 31a and the pulse output from the encoder 17 via the vector detection circuit 31a, and the home position (HP) of the rotating body 4a. ) (That is, the position where the yellow developing device 4Y is 45 degrees below the developing position as shown in FIG. 6) is output to the motor control CPU 31d. The home position sensor XO is arranged at the reference position HP, and inputs a clear signal to the position counter 31b when the rotating body 4a reaches HP. The speed counter 31c counts the pulses output from the rotary encoder 17 for a certain period of time set by the timer 31f, and the count value, that is, speed data, is stored in the motor control CPU 31.
output to d. The timer 31f generates a signal each time a set time has elapsed, and outputs this signal to the interrupt terminal of the motor control CPU 31d. Upon receiving this signal, the motor control CPU 31d executes the interrupt program and fetches the count values of the position counter 31b and the speed counter 31c. Then, the motor 12 is controlled by this value. Also, the signal from the timer 31f is the speed counter 31
It is also applied to c to clear the speed counter 31c. Further, the timer 31f is set and reset by a signal from the motor control CPU 31d.

[0018]

[Table 1]

The RO in the motor control CPU 31d
The M (read only memory) 31d1 stores the relationship between the mode and the rotation amount shown in Table 1 and the relationship between the rotation movement amount and the rotation speed shown in the graph of FIG. 5 as a table.

Next, the rotation control of the rotating body 4a of the developing device 4 in this embodiment will be described. As described above, the speed control table corresponding to the target position SD-rotational speed characteristic as shown in FIG. 5 is stored in the ROM 31d in the motor control CPU 31d.
1 and compares the speed data of the speed table of the ROM 31d1 that is accessed according to the value of the position counter 31b detected by the timer 31f at regular intervals with the speed data detected by the speed counter 31c. The driving force of the motor 12 is controlled so as to correct the deviation.

The speed control table is a ROM according to the amount of rotation.
A plurality of the necessary tables are prepared from the ROM depending on the combination of the developing machines used.

Table 2 shows the mode setting for setting the rotation mode of the rotating body.

[0023]

[Table 2]

Further, 32 is a sequence controller,
A signal is input to the motor control CPU 31d via the I / O port 33 and the load drive circuit 34 to control it. Reference numeral 35 is a key / display scanning unit provided with keys for operating and displaying the image forming apparatus, and 36 is an input interface.

In this embodiment, when the arrangement is as shown in FIG. 6 (when the yellow developing device 4Y is on the downstream side of 45 ° with respect to the developing position), the home position (HP) of the rotary developing device is set, and the copy sequence is completed. After that, it returns to HP and waits for the next cycle.

As shown in Table 1, 4 types of single color mode, 6 types of 2 color mode, 1 type of 3 color full color mode and 1 type of 4 color full color mode are prepared, and the key / display scanning unit 3 is used.
By specifying the color mode from 5, the rotation sequence of the rotating body is selected.

For example, when the three-color full-color mode is designated, first the HP is rotated by 45 ° to perform yellow development, and then the image is further rotated by 90 ° to perform magenta development. Then, it is further rotated 90 °, and after cyan development is rotated 135 ° to HP. Table 1 shows the relationship between the color mode and the rotation amount. As shown in Table 1, the rotation amount during each development is 45 °, 90 °, 135 °, 180 °, 225 shown in Table 2.
There are seven types, °, 270 ° and 315 °.

Corresponding to this rotation amount, the rotation modes shown in Table 2 are used as 3-bit mode setting signals from the I / O port 33 through the load drive circuit 34 and the motor control CPU 3
It is input to 1d as a 3-bit signal of M0, M1 and M2.

By this rotation mode command, the CPU 31d
A speed data table corresponding to each rotation amount in the table is extracted as a lookup table.

In this way, the speed control table can be selected according to the amount of rotation to drive and control the rotating body at a target position in accordance with the target motion characteristic.

However, in general, it is difficult to smoothly decelerate to the target position SD to be stopped as shown in FIG. 5 so that the speed becomes completely zero. In the case where the velocity becomes 0 at a point earlier than the target SD point and the vehicle accelerates again toward the SD point (graph a) as in 7, the target SD point is still in the middle of the deceleration process. In most cases (graph b). In such a case, the rotating body 1a has speed at the position where it should be stopped.

In this embodiment, the rotational energy of the rotating body is absorbed at the position to be stopped, the rotating body is stopped at the position to be stopped, and the rotating body is held at that position, as shown in FIGS. As described above, a positioning member including the stopper arm 19 and the stopper plate 18 is provided.

That is, on the rear side plate 11 of the rotating body 4a, the stopper plate 18 set at the position where the rotating body 4a should be stopped.
Is fixed, and the roller 22 of the stopper arm 19 is engaged with the groove 18a of the stopper plate 18 to ensure the stop position.

In the state shown in FIG. 8, the roller 22 is the stopper plate 1.
8 (HP), and the rotating body 4a is in the home position state (see FIG. 6).

The stopper plate 18 includes a stopper plate 18 (Y) for holding the yellow developing device 4Y at the developing position, 18 (M) for magenta, 18 (C) for cyan, and 18 (BK) for black. There are seeds, and each is screwed to the regular position so that it can be adjusted. The stopper arm 19 is rotatably supported by a pin 20 fixed to the main body, and a spring 28 applies a force in a direction in which the roller 22 enters the groove 18a of the stopper plate 18. The solenoid 25 is opposed to the force of the spring. When is pulled, the arm rotates around the pin 20 and the roller 22 comes out of the groove 18a of the stopper plate 18.

In order to stop the yellow developing device 4Y at the developing position by rotating it from the state of FIG. 8 by 45 °, the magnetic force of the solenoid 25 is released before the stopper plate 18 (Y) reaches the position of the pin 20. This timing is calculated by the position counter 31b in FIG.
When 1b becomes larger than a certain value, the pre-end signal (P
END) is input from the CPU 31d to the input interface 36.

The stopper arm 19, which is released from the attraction force of the solenoid, receives the stopper pin 2 by the force of the spring 28.
The roller 22 rotatably supported at 0 is abutted against the stopper plate 18.

FIG. 9 shows this state, in which the roller 22 is moved along the arcuate edge of the stopper plate 18 rotating in the N direction.
Rotates and engages the upcoming 18a.

At the moment when the roller 22 enters the engaging groove, the stopper arm 19 blocks the optical path of the photo interrupter 29 attached to the main body and detects the engaged state of the positioning member.

This detection signal is input to the I / O port 33 on the main body side of FIG. 4, and a TOFF signal enters the CPU 31d from the main body side I / O port 33 side by this signal to cut off the drive torque or control torque of the rotating body. To do.

FIG. 10 shows the moment when the roller 22 engages with the groove 18a of the stopper plate 18. At this time, the drive torque of the drive motor 12 disappears, but there is extra rotation due to inertia. Due to this inertial force, the roller 22 moves into the groove 1
It is pulled by the rotating body 4a while being engaged with 8a. The stopper arm 19 resists the force of the spring 23 connecting the pin 21 and the pin 20 along the elongated hole 19a at the center of rotation of the stopper arm 19 as shown in FIG.
Moves by Δθ.

This movement amount Δθ is a value in which the rotational energy of the rotating body is in accordance with the elastic energy of the spring 23, and the rotating body 4a is returned to the normal position by the restoring force of the spring and the positioning is completed (FIG. 10). .

When moving to the next rotation, first the solenoid 2
5 is excited to rotate the stopper arm 19 around the pin 20 to release the engagement between the groove 18a of the stopper plate 18 and the roller 22. By this operation, the stopper arm 19 that has shielded the photo interrupter 29 retracts from the optical path of the photo interrupter and a stopper release signal is input to the sequence controller 32.
Is transmitted from the CPU 31d for motor control as a start signal for instructing the rotation start of the rotating body 4a.

By inputting this signal, the rotator 4
a starts to rotate, the solenoid 25 is turned off by the PEND signal, and when the photo interrupter 29 detects that the roller 22 is engaged with the groove 18a, the difference between the target position counter value and the actual position counter value is forced. To 0 to turn off the torque of the drive motor 12.

The operation will be described with reference to the flowchart of FIG.

When the power of the apparatus main body is turned on (STEP
-1), the device is reset (STEP-2), key
It becomes possible to accept an input from the display scanning unit 35 with a key (STEP-3). Then, when the print key is turned on (STEP-4), pre-copy rotation is performed to move the rotating body 4a to HP (STEP-).
5). At the same time, it is determined whether or not the rotary member 4a of the multi-color developing device is at HP by the presence or absence of a signal from the home position sensor XO (STEP-6). At this time, when the rotating body 4a is not in the HP, the timer in the sequence cotton roller 32 is activated, and the sequence controller 32 causes the rotating body 4a to move.
Command signal for moving the motor to the HP via the I / O port 33 and the load drive circuit 34
Input to d (STEP-7). However, if the rotating body 4a is not in the HP before the timer setting time elapses, C
A signal ARAM is output from the PU 31d (STEP-
8), based on this signal, the sequence controller 3
2 is regarded as an abnormal state, and abnormal processing such as device stop is performed (STEP-9).

On the other hand, when the rotating body 4a rotates to the HP before the timer setting time elapses or is already in the HP, the operator operates the key / display scanning unit 3
Depending on the mode selected by the appropriate key operation of 5,
The signals (M0, M1, M2) shown in Table 2 are input from the sequence controller 32 to the motor control CPU 31d via the I / O port 33 and the load drive circuit 34. In the motor control CPU 31d, data relating to the mode selected by the operator and the table corresponding to the graph shown in FIG. 5 are stored in the ROM 31d1 to the RAM 31d2.

At the same time, the lock solenoid 25 of the positioning means Z is turned on. Then, the stopper plate 18HP and the roller 22 are disengaged, and at the same time, the end of the stopper arm 19 retreats from the optical path of the photo interrupter 29, and the release signal of the stopper arm 19 from the photo interrupter 29 is sequenced as the start signal of the rotating body 4a. It is input to the controller 32 (STEP-10). In order to confirm that the holding of the rotating body 4a by the above-mentioned positioning means Z is released, the presence or absence of a start signal from the photo interrupter 29 is determined (STEP-11). If there is no such signal, stop the lock solenoid ON signal and then
It is turned on again (STEP-12), and at the same time, the elapse of the timer setting time is determined (STEP-13). If there is no lock solenoid ON signal within the time, the abnormality processing is executed by the timer discrimination sequence similar to STEP-9 (STEP-14). If there is a start signal, the rotating body 4
A is controlled and driven by the driver 30 as shown in FIG. 5 (STEP-15). Whether or not the developing device of the moved rotating body 4a is correctly located at the target developing position is determined by the contents of the set table of the sequence controller 32 and the sensors XY, XM, XC, X provided corresponding to each developing station.
It is judged from the correspondence with the input from the BK to the input interface 36 (STEP-16). If it is not at the target position, the timer in the sequence controller 32 is set, and the correspondence between the position detection plate X1 and each of the development position sensors XY to XBK is confirmed. The rotating body 4a is moved at a low speed (STEP-17). For some reason, the roller 22 of the stopper arm 19 causes the stopper plate 1 at the target developing position to move.
Since it may be disengaged after once engaging with 8, in such a case, the rotating body 4a is further rotated to control so as to reach the target developing position. If this movement is not performed within the predetermined time (STEP-18), the signal ARAM is output to the motor control CPU 31d and the abnormality processing is performed (STEP-19). On the other hand, if the predetermined developing device is at the target developing position, the copy mode for that color is executed (STEP-20), and the above-mentioned STEP-10 to STEP-21 are repeatedly executed until the copy mode ends. , The development position is switched and development is performed. Then, when the instructed copy mode ends, the after rotation mode is performed, the rotating body 4a is moved to the home position HP (STEP-22), and the process returns to STEP-4.

FIG. 13 is a flowchart of the rotary body drive control.

After the copy key is turned on as described above, the rotating body 4a
If is in the home position, the sequence controller 32 executes a rotating body moving routine. First, the solenoid 25 is turned on by outputting a drive signal via the load drive circuit 34 in order to remove the roller 22 of the stopper arm 19 from the groove of the stopper plate 18 (STEP-30).
Rotation mode (M0, M
1, M2) is output to the motor control CPU 31d (S
TEP-31). Then, the ON signal of the photo interrupter 29 due to the roller 22 coming off the stopper plate 18 is inputted through the input interface 36 (STEP
-32), START to the motor control CPU 31d
A signal is output (STEP-33). As a result, the motor control CPU 31d controls the movement of the rotating body 4a. When the pre-end signal (PEND) is input from the motor control CPU 31d to the sequence controller 32 via the input interface 36 (STEP-3
4) Turn off the solenoid 25 (STEP-3
5). Then, the photo interrupter 2 showing that the roller 22 of the stopper arm 19 is engaged with the groove of the stopper plate 18.
When the OFF signal of No. 9 is input via the input interface 36 (STEP-36), the TOFF signal is sent to the motor control C via the I / O port 33 and the load drive circuit 34.
It outputs to PU31d (STEP-37). As a result, the drive torque of the rotating body is cut off.

Next, the control of the motor control CPU 31d will be described with reference to FIG.

When the power of the apparatus main body is turned on, a reset signal (RESET) is supplied to the motor control CPU 31d to initialize the CPU internal RAM and I / O port settings, and the home position sensor of the rotating body 4a. The input of XO is discriminated (STEP-40). If it is not at the home position (STEP-41), predetermined data is sent to the D / A converter 31g to operate the motor. Here, data is sent from the motor control CPU 31d through an 8-bit bus, and the motor speed is 0 at OOH and full speed at FFH. Further, a predetermined timer is set (STEP-42), it is determined whether or not the timer value is reached (STEP-43), and if it is within the timer time, the process returns to (STEP-41), and if it is the timer time or more, Signal to sequence controller 32 AR
AM is output (STEP-).

When the home position detection signal is input,
The motor control CPU 31d sets the position counter 31b to 0H.
(STEP-44). However, the speed at this time is (ST
Since the speed is in accordance with the value given in EP-43) and the stop impact is large, the motor 12 is operated again at this point (STEP-45) to stop the next home position stop SUB.
Then, the speed is controlled by the position counter 31b up to the home position, and the speed is controlled to be sufficiently slow near the stop position to stop the motor (S
TEP-46). Next, the input signal of the input port of the motor control CPU 31d is processed (STEP-47). Next, it is determined whether or not there is a START signal (STEP-4
8) If not, return to (STEP-47), and if there is, enter the mode from the input port, and use the entered value to read the speed table from the ROM 31d inside the CPU 31d for motor control.
It is called from 1 and stored in the RAM 31d2. The table values in the RAM 31d2 are sequentially read by the interruption of the timer 31f and set as the speed control target value (STEP-
49). Next, the target value is loaded to operate the motor and enable the timer 31f to oscillate (STEP-5
0). As a result, a signal is input to the interrupt terminal of the motor control CPU 31d. Thus, the deviation between the previous speed control target value and the actual speed counter 31c is subjected to a predetermined calculation with respect to the current speed control target value and output to the D / A converter 31g. The value of the position counter 31b is controlled so as to be an acceleration system up to a half of the target position and becomes a deceleration system thereafter, and is controlled so that the control minimum speed is reached at the point of reaching the target position counter value (STEP-51).
Next, when the TOFF signal is input from the sequence controller 32 or the difference between the target value counter value and the actual position counter value becomes 0, the motor 12 is turned off and the timer 3
Turn off 1f and return to STEP-47 (STEP-5
2). It should be noted that the motor control CPU 31d performs TO before the difference between the target position counter value and the actual position counter value becomes zero.
When the FF signal is input, the "difference" is forcibly set to zero.

[0054]

As described above, according to the present invention, the holding means for integrally holding a plurality of developing devices is provided,
In the image forming apparatus for developing the latent image formed on the photosensitive member by driving the holding unit to move the developing unit, a desired one of the plurality of developing units included in the holding unit is exposed to light. With a simple structure, the holding means can be driven in order to reliably move the latent image formed on the body to a position where it can be developed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a color image forming apparatus to which the present invention is applied.

FIG. 2 is a perspective view showing a drive system and a positioning member of the rotary developing device.

FIG. 3 is an enlarged perspective view showing a positioning member of the developing device.

FIG. 4 is a block diagram showing a control unit of the image forming apparatus.

FIG. 5 is a graph showing the relationship between the rotational movement amount and the rotational speed.

FIG. 6 is a diagram showing a rotating body located at a home position.

FIG. 7 is an explanatory diagram showing the speed of the rotating body near the target SD to be stopped.

[FIG. 8] In the home position, the roller 22 is the stopper plate 1
8 is a view showing a state of being engaged with the groove 18a of FIG.

FIG. 9 is a view showing a state where the roller 22 is in contact with an arcuate edge of the stopper plate 18.

FIG. 10 is a view showing a state in which the roller 22 is engaged with the groove 18a of the stopper plate 18.

11 is an explanatory view showing that the roller 22 moves by Δθ after engaging with the groove 18a of the stopper plate 18. FIG.

FIG. 12 is a control flowchart of a sequence controller

FIG. 13 is a flowchart of a rotational movement routine.

FIG. 14 is a control flowchart of a motor control CPU 31d.

[Explanation of symbols]

4a Rotating body 4Y Yellow developing device 4M Magenta developing device 4C Cyan developing device 4BK Black developing device 12 Motor (driving means) 18Y, 18M, 18C, 18BK Stopper plate (stopping means) 18a Groove (stopping means) 22 Roller (stopping means) 29 Photointerrupter (stop detecting means) 30 Driver (driving means) 31 Control means X Developing position detecting means (reference position detecting means) Z Positioning means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Murayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. An image forming apparatus for forming a color image by developing a latent image formed on a photoconductor by using a plurality of developing devices each containing a developer of a different color, wherein the plurality of developing devices are provided. Holding unit for integrally holding the developing unit, a storing unit for storing a moving amount of the developing device held by the holding unit as a table, and a plurality of developing units based on the moving amount obtained by referring to the table. An image forming apparatus comprising: a driving unit that drives the holding unit so that one of the containers comes to a position where the latent image formed on the photoconductor can be developed. 2. An image forming apparatus for forming a color image by developing a latent image formed on a photoconductor using a plurality of developing devices each containing a developer of a different color, wherein the plurality of developing devices are provided. Holding unit that integrally holds the developing unit, a driving unit that drives the holding unit, a storing unit that stores the moving amount of the developing device held by the holding unit, and the plurality of developing units based on the moving amount. So that one of the containers comes to a position where the latent image formed on the photoconductor can be developed.
An image forming apparatus comprising: a microprocessor that controls the driving unit.