JP4856820B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a printer or a copying machine, and more particularly to an image forming apparatus having a plurality of developing devices on a movable developing device holder.
[0002]
[Prior art]
Among image forming apparatuses, several different methods are known for electrophotographic color image forming apparatuses that form two or more color images, such as a color image forming apparatus. One method is a method (hereinafter referred to as a tandem method) including an image forming station composed of the same number of photoconductors, chargers, developing devices, and the like as colors necessary for image formation. This method is suitable for high-speed color image formation. In the method disclosed in Japanese Patent Laid-Open No. 2-254868, a method of forming a color image by providing only a single photoconductor and repeating the same number of image forming cycles as the color of the developer (hereinafter referred to as a rotary method). ). This method can realize a small and low-cost apparatus. In the above method, a method using an intermediate transfer member is also realized. Further, as disclosed in Japanese Patent Application Laid-Open No. 61-51534, there is a method in which only a single photoconductor is provided and a latent image of a plurality of colors is formed on the photoconductor within one rotation. As for color image forming apparatuses, those in which the formed image is close to a silver salt photograph are on the market, and it is considered that the color image forming apparatus will be rapidly spread.
[0003]
However, at present, the cost of color image forming apparatuses is rapidly decreasing in the general market, and various techniques have been introduced in order to reduce costs in each method.
[0004]
Of these, stepping motors are generally used when paying attention to the driving method of the rotary type developing device holder of the rotary type, which is the smallest and can be reduced in cost. However, in order to increase the speed and silence of a rotary type color image forming apparatus, selection of the motor has become important due to problems of torque increase and size.
[0005]
In a conventional rotary type rotary developer holder control method, the number of pulses of the stepping motor is counted, and control is performed using a reference position detection sensor of the rotary developer holder.
[0006]
[Problems to be solved by the invention]
However, in a non-contact type development system (also called jumping development) at the time of image formation, it was effective with a combination of a stepping motor and a reference position detection sensor. In the developing system, the positional accuracy of the photosensitive member and the developing unit has a great influence on the image quality. In addition, in order to prevent the rotary developing device holder from moving during development, the driving means of the rotary developing device holder is locked by applying excitation, but there may be a problem with slight vibration during excitation. Many. In addition, there is a problem that there is no detection means in the case of a stepping motor when the rotary developer holder does not reach the specified position due to the current step-out. In addition, when a gear having a large reduction ratio is used to compensate for the number of steps, there is a problem of increasing costs.
[0007]
SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to solve the problems of a stepping motor by driving a movable developing device holder.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a typical configuration of the present invention includes a driving unit having a rotating shaft and being driven by the driving unit. rotation And a developing device holder for holding a developing device for forming a developer image on the photosensitive member; ,in front A reading member that moves in accordance with the rotation of the rotary shaft; ,in front A reference position detecting means for detecting a reference position of the developing device holder; A moving distance detecting unit that detects a moving distance of the reading member and resets the moving distance when the reference position is detected by the reference position detecting unit; Have In the image forming apparatus, the movement distance detected by the movement distance detection unit does not reach the specified distance within a specified time after the reference position detection unit detects the reference position of the developing device holder. The driving unit is driven until the moving distance detecting unit detects the moving distance corresponding to at least one rotation of the developing unit holder, and the reference position of the developing unit holder is driven by the reference position detecting unit. Is not detected, it is determined that the developing device holder is rotating abnormally. It is characterized by doing.
[0009]
With the above configuration, it does not depend on the number of pulses of the driving means Reading member With very fine accuracy Developer The holding body can be controlled.
[0010]
further, developing Detecting the reference position of the holder means Use to find the origin developing By storing the total number of pulses of one rotation or more of the container holder, control at an arbitrary position is possible.
[0011]
Also, Above Stop means for stopping or canceling the movement of the developing device holder is provided, and the stop means further uses a solenoid. Above By locking or unlocking the movement of the developer holder, developing It becomes possible to omit the excitation of the driving means when the cage holder is stopped.
[0012]
Therefore, the cost is minimized and developing It can be very functional for the control of the container holder.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. As long as there is no specific description, it is not the meaning which limits the scope of the present invention only to them.
[0014]
[First Embodiment]
The image forming apparatus according to the first embodiment of the present invention will be described in detail with reference to FIGS. First, FIG. 2 shows an example of an image forming apparatus to which the present invention is applied.
[0015]
As shown in FIG. 2, the image forming apparatus used in the present embodiment has a photosensitive drum 100, an optical unit 101, a charging roller 102, a primary transfer roller 103, an intermediate transfer body tension roller 104, an intermediate transfer as main functions. Body driving roller 105, intermediate transfer body cleaning roller 107, rotary developing device holder 150, rotary developing device holder driving means (hereinafter referred to as a motor) 161, four developing means (developing devices) 151a, 151b, 151c, 151d, a rotary developing device reference position detection sensor 131 (hereinafter referred to as a home position sensor) as a reference position detection means, a conveyance belt 121, a fixing unit 126, a paper feed tray 200, a manual paper feed tray 124, a density and timing sensor 130. , Secondary transfer roller 120, paper discharge roller 162, paper discharge tray 125, and upper paper discharge It has a ray 128 and the like.
[0016]
Next, an outline of the process up to printing will be described. First, the surface of the photosensitive drum 100 is uniformly charged to a desired polarity (for example, −600 V) by the charging roller 102 disposed on the photosensitive drum 100. Next, based on the image data sent from the controller based on the image synchronization signal, the optical unit 101 is used to expose the surface of the photosensitive drum 100 with the laser L, thereby forming a latent image on the photosensitive drum. As an example of a process for visualizing the latent image, for example, a latent image formed on the photosensitive drum 100 by the Y (yellow) developing unit 151a, that is, a predetermined voltage is applied to the developing sleeve 152 (for example, − 300V), the latent image on the photosensitive drum 100 is developed with a developer such as toner, and a visualized toner image is formed on the photosensitive drum 100.
[0017]
Thereafter, the toner image on the photosensitive drum 100 is temporarily transferred to the intermediate transfer member 109 by the primary transfer roller 103, and the image is held for the time being.
[0018]
Similarly, for M (magenta), C (cyan), and Bk (black), latent images corresponding to the respective image data are sequentially developed on the photosensitive drum 100 by the respective color developing units 151b to 151d, and the respective developments are performed. A toner image is formed by developing with the developing sleeve and toner of the means, and sequentially transferred to the intermediate transfer body 109 for each color to hold the image.
[0019]
Since the held toner images of the respective colors on the intermediate transfer body 109 are transferred at a predetermined timing, they become multiple toner images on the intermediate transfer body 109. On the other hand, after the development with the last image forming color is completed, the secondary transfer roller 120, the intermediate transfer member cleaning roller 107, and the intermediate transfer member driving roller 105 are brought into contact with each other via the intermediate transfer member 109 at a predetermined timing. . After making contact with the intermediate transfer body 109, a high voltage (for example, +1000 V) having a polarity opposite to the toner image (for example, positive polarity) is applied to the secondary transfer roller 120 at a predetermined timing. Similarly, a positive polarity voltage (for example, +1000 V and a rectangular wave voltage (for example, 1 KHz, 2 KVpp)) is applied to the cleaning roller 107, and a voltage having the same polarity and the same potential as the primary transfer roller 103 is applied to the intermediate transfer body driving roller 105. Apply and wait for transfer material transfer.
[0020]
Further, the transfer material is fed from the paper feed tray 200 by the paper feed roller 127 or from the manual paper feed tray 124 by the paper feed roller 123 at a predetermined timing required for transferring the toner image. The transferred transfer material is temporarily stopped by the registration roller 122 and waits for completion of the final color image formation on the intermediate transfer body 109.
[0021]
After the final color image formation is completed, the registration roller 122 starts to re-transfer the transfer material at a desired timing. The conveyed transfer material is conveyed between the abutting secondary transfer roller 120 and the intermediate transfer member 109 driven by the intermediate transfer member driving roller 105, and the multi-color multiple toner image on the intermediate transfer member 109 is intermediate. The image is transferred onto the transfer material by the potential difference between the biases applied to the transfer body driving roller 105 and the secondary transfer roller 120. Thereafter, the toner remaining on the intermediate transfer member 109 after the transfer is removed by the cleaning roller 107 or recharged, and the residual toner on the intermediate transfer member 109 returns to the photosensitive drum 100 by recharging, and the photosensitive drum 100 is recharged. It is collected by the cleaning blade 110 in contact with the. The residual toner collected by the cleaning blade 110 is accumulated in the waste toner area 108 by a drive system (not shown). Further, the residual toner adhering to the cleaning roller 107 is collected on the photosensitive drum 100 later by a predetermined process.
[0022]
After the transfer to the transfer material is completed, the cleaning roller 107 and the secondary transfer roller 120 are separated from the intermediate transfer member driving roller 105 to prepare for the next image formation.
[0023]
Note that the surface of the photosensitive drum 100 that has been cleaned is again charged uniformly to a desired polarity by the charging roller 102 to prepare for the next latent image forming and developing process. The same applies to the intermediate transfer member 109 from which residual toner has been cleaned.
[0024]
On the other hand, the transfer material onto which the toner image has been transferred is conveyed by the conveyance belt 121, and the toner image is fixed to the transfer material by the fixing unit 126. The transfer material on which the toner image is fixed is discharged to the upper discharge tray 128 or the lower discharge tray 125.
[0025]
The manual paper feed tray 124 can be opened and closed as required by the user, and the tray itself can be expanded and contracted according to the size of the transfer material. Similarly, for the lower discharge tray 125, the sub-stay of the discharge tray can be expanded and contracted. Further, the upper paper discharge tray can be extended and contracted by a stopper guide (not shown) according to the size of the transfer material.
[0026]
The density / timing sensor 130 is for controlling the density of each color toner image at the time of warm-up when the color image forming apparatus is turned on or at a predetermined timing. As for timing, a reference position on an intermediate transfer member (not shown) is read by a reflection or transmission method and used as a means for detecting a reference at the time of image formation. In the present embodiment, the density and timing sensor 130 is described as one unit, but it may be a separate unit.
[0027]
The outline of the printing process in the color image forming apparatus used in this embodiment has been described above. When this color image forming apparatus is used, a full color image with very high precision and good color reproducibility can be obtained.
[0028]
Next, in the above-described image forming apparatus, the basic configuration of the control system of the rotary developing device holder 150 according to the present embodiment will be described below with reference to the drawings.
[0029]
FIG. 1 shows an outline for carrying out the present invention in the image forming apparatus used in this embodiment. The block diagram of FIG. 1 is a diagram relating to the control system of the rotary developer holder 150 used in this embodiment.
[0030]
The CPU 300 as the control means performs control based on information from the motor 161 as the driving means of the rotary developing device holder 150, the encoder 171 as the moving distance reading means, and the home position sensor 131 as the reference position detecting means. ing. Further, the FMT 400 as the image data input means in FIG. 1 is generally called a controller, and notifies the user when there is an abnormality in the rotation of the rotary developer holder 150 or other information. .
[0031]
A control method in the control system of FIG. 1 will be described. First, the CPU 300 drives the motor 161 when driving the rotary developer holder 150. When the motor 161 starts to rotate by driving, the amount of movement associated with the rotation angle is detected by the encoder 171 and the result is returned to the CPU 300. The CPU 300 performs drive control such as acceleration and deceleration of the motor 161 according to the amount of movement. Further, the rotary developing device holder 150 starts rotating by a driving roller 160 via a motor 161. When the rotary developer holder 150 rotates, a flag (not shown) of the rotary developer holder 150 always passes through the home position sensor 131 within one rotation. In this embodiment, the amount of movement detected by the encoder 171 when the flag passes (when the flag is detected by the home position sensor 131) (in this embodiment, the number of pulses detected by the encoder 171 (the number of marks on the code wheel 170)) is recognized. Used as counter reset.
[0032]
FIG. 3 is an excerpt of a portion related to the present embodiment from the image forming apparatus used in the present embodiment. FIG. 4 is an enlarged view of the drive gears of the motor 161, the drive roller 160, and the rotary developing device holder 150 in FIG. The motor 161 in FIG. 4 is attached to the main body frame 50. Then, on the motor shaft on the non-driving side of the motor 161, a code wheel 170 which is a rotation speed read-only member, and a movement distance for reading the movement amount of the rotary developing device holder 150 by reading the mark on the code wheel 170 An encoder 171 serving as reading means is arranged. The code wheel 170 is press-fitted onto the motor shaft on the non-driving side of the motor 161 (or any other attachment method such as screw fixing may be used). The encoder 171 reads the mark on the code wheel 170 and passes the read information to the CPU 300 in FIG. The CPU 300 can also know the rotation speed from the time interval of the pulses (code wheel marks) detected by the encoder 171.
[0033]
FIG. 5 is a diagram schematically showing an example of the mark on the code wheel 170 and the arrangement of the encoder 171. The mark on the code wheel shown in FIG. 5 is an example, and the present invention is not limited to this. FIG. 6 is a block diagram of a sequence relating to the control of the initial rotation type developing device holder 150 of the present embodiment. First, in S1, the initial control of the rotary developer holder is started. Next, in S <b> 2, the CPU 300 starts driving the motor 161 and starts rotating the motor 161. Next, in S3, the CPU 300 drives the motor 161 until the home position sensor 131 is detected. S4 is a sequence for determining whether or not the home position sensor 131 has detected within the specified time of the motor 161. When the home position is detected within the specified time, the process proceeds to the process 1 sequence of S11 following FIG. If the home position cannot be detected within the specified time, it is determined that the rotation of the rotary developing device holder 150 is abnormal in S31, and the rotational driving of the rotary developing device holder 150 is stopped (emergency stop or the like) in S32. Thereafter, in S30, for example, the FMT 400 in FIG. 1 shifts to error processing such as notification to the abnormal user or a self-diagnosis mode in the image forming apparatus.
[0034]
FIG. 7 is a sequence block diagram when the process proceeds to S11 as described above. First, in S11, rotation control of the rotary developing device holder 150 is started. In S12, the CPU 300 drives the motor 161 to rotate the motor 161. In step S13, the number of pulses detected by the encoder 171 during motor rotation is monitored. Next, in S14, it is determined whether or not the designated pulse count has been completed within the designated time. If the designated pulse count has been completed, the rotary developing device holder 150 in S15 is stopped at the designated position. Then, the rotation control of the rotary developing device holder 150 in S16 is finished. If the pulse count does not end within the designated time, the motor is driven to the estimated home position sensor confirmation position in S17. This is because the pulse count is reset by the above-described initial home position detection, and the number of detected pulse counts in the encoder 171 for one rotation of the rotary developer holder 150 used in this embodiment is determined. The estimated home position sensor confirmation position is known in advance. In the present embodiment, in the above-described sequence of S17, determination is made by driving up to the estimated home position sensor confirmation position up to the pulse count number to several percent. Note that the number of determination pulses described above may be an arbitrary value as long as it is actually within the range allowed by the system. In S18, it is determined whether or not the home position sensor at the estimated home position sensor confirmation position has been detected. If the home position can be detected, the rotary developer holder is controlled to move to the designated position in S19, and the process returns to the sequence in S14. If the home position sensor cannot be confirmed, the process proceeds to the sequence after S31 which is the determination of the rotation abnormality of the rotary developing device holder 150 described in FIG.
[0035]
As described above, by using the code wheel 170 that is a read-only member that does not depend on the number of pulses of the motor, it is possible to control the movement of the rotary developer holder 150 with very fine accuracy.
[0036]
In other words, according to the present embodiment, when the rotation type developer holder is abnormally rotated, self-diagnosis is facilitated and can be stopped quickly, thereby burdening the driver for driving the motor. Can be greatly reduced.
[0037]
[Second Embodiment]
The image forming apparatus according to the second embodiment of the present embodiment will be described in detail with reference to FIGS.
[0038]
In the present embodiment, a description will be given of a rotary developer holding member added with a solenoid lock mechanism. FIG. 8 is a block diagram of a sequence relating to the control of the initial rotating developing device holder 150 with a locking mechanism by a solenoid according to the present embodiment. First, in S1, the initial control of the rotary developing device holder 150 is started. Next, when starting the rotation of the motor 161 in S5, the lock mechanism 253 of the rotary developing device holder 150 is released by the solenoid 252. Next, in S2, the CPU 161 starts driving the motor 161, and the motor 161 starts to rotate. Next, in S3, the CPU 300 drives the motor 161 until the home position sensor 131 is detected. S4 is a sequence for determining whether or not the home position sensor 131 has detected within the specified time of the motor 161. When the home position is detected within the specified time, the process proceeds to the process 2 sequence of S41 following FIG. If the home position 131 cannot be detected within the specified time, it is determined that the rotation of the rotary developer holder 150 is abnormal in S31, and the rotation drive of the rotary developer holder 150 is stopped (emergency stop or the like) in S32. . In S33, the lock mechanism 253 of the rotary developing device holder 150 is locked by the solenoid 252. Thereafter, in S30, for example, the FMT 400 in FIG. 1 shifts to error processing such as notification to the abnormal user or a self-diagnosis mode in the image forming apparatus.
[0039]
FIG. 9 is a sequence block diagram when the process proceeds to S41. First, in step S41, rotation control of the rotary developing device holder 150 is started. In S42, the CPU 300 drives the motor 161 to rotate the motor 161. In step S43, the number of pulses detected by the encoder 171 during motor rotation is monitored. Next, in S44, it is determined whether or not the designated pulse count has been completed within the designated time. If the designated pulse count has been completed, the rotary developing device holder 150 in S45 is stopped at the designated position. Next, in S <b> 46, the lock mechanism 253 of the rotary developer holder 150 is locked by the solenoid 252. Then, the rotation control of the rotary developing device holder 150 in S47 is finished. If the pulse count does not end within the designated time, the motor is driven to the estimated home position sensor confirmation position in S17. In S18, it is determined whether or not the home position sensor 131 at the estimated home position sensor confirmation position is detected. If the home position can be detected, in S19, the rotary developer holder 150 is controlled to move to the designated position, and the process returns to the sequence in S44. If the home position sensor 131 cannot be confirmed, the process proceeds to the sequence of S31 and subsequent steps, which is a determination of abnormal rotation of the rotary developer holder 150 described with reference to FIG.
[0040]
FIG. 10 is a schematic diagram of this embodiment having a lock mechanism 253 with a solenoid 252. The solenoid 252 is connected to a rotary developing device holder lock mechanism 253 and includes an auxiliary member 251 for unlocking.
[0041]
Also in this embodiment, the same effect as the first embodiment described above can be obtained. Further, according to the present embodiment, the rotation of the rotary developer holder is fixed by the solenoid 252 and the lock mechanism 253 as stop means, so that it becomes safer when accessing the rotary developer holder. Further, it is possible to omit the excitation of the motor when the rotary developing device holder is stopped, which was necessary in the past.
[0042]
[Third Embodiment]
The image forming apparatus according to the third embodiment of the present embodiment will be described in detail with reference to FIGS.
[0043]
In the present embodiment, a description will be given of a rotary developing device holder added with a stop mechanism (lock mechanism) by a lock pin or a pressing member pushed out by a cam or the like. FIG. 11 is a block diagram of a sequence related to the control of the rotary developing device holder 150 at the time of initializing by the stopping mechanism of the present embodiment. First, in S1, the initial control of the rotary developing device holder 150 is started. Next, when starting the rotation of the motor 161 in S6, the lock of the rotary developing device holder stopping mechanism is released. Next, in S2, the CPU 161 starts driving the motor 161, and the motor 161 starts to rotate. Next, in S3, the CPU 300 drives the motor 161 until the home position sensor 131 is detected. S4 is a sequence for determining whether or not the home position sensor 131 has detected within the specified time of the motor 161. When the home position is detected within the specified time, the process proceeds to the process 3 sequence of S51 following FIG. If the home position cannot be detected within the specified time, it is determined that the rotation of the rotary developing device holder 150 is abnormal in S31, and the rotational driving of the rotary developing device holder 150 is stopped (emergency stop or the like) in S32. In S34, the rotary developing device holder 150 is locked by the stop mechanism. Thereafter, in S30, for example, the FMT 400 in FIG. 13 shifts to error processing such as notification to the abnormal user or self-diagnosis mode in the image forming apparatus.
[0044]
FIG. 12 is a sequence block diagram when the process proceeds to S51 as described above. First, in S51, rotation control of the rotary developing device holder 150 is started. In S52, the CPU 300 drives the motor 161 to rotate the motor 161. In step S53, the number of pulses detected by the encoder 171 during motor rotation is monitored. Next, in S54, it is determined whether or not the designated pulse count has been completed within the designated time. If the designated pulse count has been completed, the rotary developing device holder 150 in S55 is stopped at the designated position. Next, in S56, the rotary developing device holder 150 is locked by the stopping mechanism. Then, the rotation control of the rotary developing device holder 150 in S57 is finished. If the pulse count does not end within the designated time, the motor is driven to the estimated home position sensor confirmation position in S17. In S18, it is determined whether or not the home position sensor 131 at the estimated home position sensor confirmation position is detected. If the home position can be detected, the rotary developer holder is controlled to move to the designated position in S19, and the process returns to S44. If the home position sensor 131 cannot be confirmed, the process proceeds to the sequence after S31, which is the determination of the rotation abnormality of the rotary developer holder 150 described in FIG.
[0045]
FIG. 13 shows an outline for carrying out the present invention in the image forming apparatus used in this embodiment. The block diagram of FIG. 13 is a diagram relating to the control of the rotary developing device holder 150 used in this embodiment. The CPU 300 controls the rotary developer holder 150 using a motor 161, an encoder 171, a home position sensor 131, and a lock mechanism 253 as a stop mechanism (stop means). Further, the FMT 400 in FIG. 13 is generally called a controller, and notifies the user when there is an abnormality in the rotation of the rotary developer holder 151 or other information.
[0046]
The control method in FIG. 13 will be described. First, the CPU 300 first controls the lock mechanism 253 before driving the rotary developer holder 151, and then drives the motor 161. When the motor 161 starts to rotate by driving, the amount of movement associated with the rotation angle is detected by the encoder 171 and the result is returned to the CPU 300. The CPU 300 performs drive control such as acceleration and deceleration of the motor 161 according to the amount of movement. Further, the rotation type developer holder 151 starts to rotate by the driving roller 160 via the motor 161. When the rotary developer holder 151 rotates, a flag (not shown) of the rotary developer holder 151 always passes through the home position sensor 131 within one rotation. Also in the present embodiment, the amount of movement detected by the encoder 171 when the flag passes (when the flag is detected by the home position sensor 131) (in this embodiment, the number of pulses detected by the encoder 171 (the number of marks on the code wheel 170)) is recognized. Used as a counter reset.
[0047]
Also in this embodiment, the same effect as the first embodiment described above can be obtained. Further, similarly to the second embodiment described above, the rotation of the rotary developing device holder is fixed by the lock mechanism as the stopping means, so that it becomes safer when accessing the rotary developing device holder. Further, it is possible to omit the excitation of the motor when the rotary developing device holder is stopped, which was necessary in the past.
[0048]
[Other Embodiments]
In the above-described embodiment, the laser type color image forming apparatus using the rotary developing device holder has been described. However, the present invention is not limited to this. The present invention can be applied to an image forming apparatus such as a color image forming apparatus, an ink jet recording head, or an LED system having a movable developing device holder.
[0049]
Furthermore, it goes without saying that the present invention can also be applied to an image forming apparatus having a plurality of (two or more) image forming units including the present embodiment in one image forming station (for example, yellow).
[0050]
In addition, the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, interface device, reader, printer, etc.) or to a device composed of a single device (for example, a copier, a facsimile apparatus, etc.). good.
[0051]
In the above-described embodiment, the contact-type development system (method for performing development in a state where the photosensitive drum and the developing device are in contact with each other) is described as an example. However, the present invention is not limited to this. Needless to say, the present invention is also useful in other development systems, for example, a non-contact development system (a system in which development is performed in a state where the photosensitive drum and the developing device are separated from each other).
[0052]
【Effect of the invention】
As explained above, according to the present invention, The movement of the developer holder can be controlled with fine precision. .
[Brief description of the drawings]
FIG. 1 is a block diagram relating to a control system for a rotary developer holder according to a first embodiment.
FIG. 2 is a schematic configuration diagram of an image forming apparatus.
FIG. 3 is a schematic view of a main part around a rotary developing device holder in the image forming apparatus.
FIG. 4 is a schematic diagram of a driving portion of a rotary developing device holder.
FIG. 5 is a schematic diagram of an encoder reading method.
FIG. 6 is an initial sequence diagram according to the first embodiment.
FIG. 7 is a control sequence diagram of the rotary developer holder according to the first embodiment.
FIG. 8 is an initial sequence diagram according to the second embodiment.
FIG. 9 is a control sequence diagram of the rotary developing device holder according to the second embodiment.
FIG. 10 is a schematic diagram of a solenoid lock mechanism according to a second embodiment.
FIG. 11 is an initial sequence diagram according to the third embodiment.
FIG. 12 is a control sequence diagram of the rotary developing device holder according to the third embodiment.
FIG. 13 is a block diagram relating to a control system for a rotary developing device holder according to a third embodiment.
[Explanation of symbols]
L ... Laser
50 ... Body frame
100: Photoconductor drum
101 ... Optical unit
102 ... Charging roller
103 ... Primary transfer roller
104 ... Intermediate transfer member tension roller
105. Intermediate transfer member driving roller
107 Intermediate roller cleaning roller
108 ... Waste toner area
109 ... Intermediate transfer member
110 ... Cleaning blade
120 ... Secondary transfer roller
121 ... Conveyor belt
122… Register Roller
123 ... paper feed roller
124 ... Manual feed tray
125 ... Output tray
126. Fixing unit
127 ... paper feed roller
128 ... Upper output tray
130 ... Timing sensor
131 ... Rotary developer reference position detection sensor (home position sensor)
150... Rotating developer holder
151a, 151b, 151c, 151d ... developing means
160. Driving roller
161: Motor
162 .. discharge roller
170 ... code wheel
171 ... Encoder
200 ... paper feed tray
251 ... Auxiliary member
252 ... Solenoid
253... Rotating developer holder lock mechanism
300 ... CPU
400 ... FMT

Claims (9)

Drive means having a rotation axis;
Rotated by being driven by said drive means, a developing device holder for holding the developing units for forming a developer image on the photosensitive member,
A reading member moving in response to rotation of the front Symbol rotary shaft,
A reference position detecting means for detecting the reference position before Symbol developing device holder,
In the image forming apparatus to have a, a moving distance detecting means for resetting the moving distance when detecting the reference position by the reading the movement distance of the member detects said reference position detecting means,
If the moving distance detected by the moving distance detecting means does not reach the specified distance within a specified time after the reference position detecting means detects the reference position of the developing device holder, at least the developing device. When the driving means is driven until the moving distance corresponding to one rotation of the holding body is detected by the moving distance detecting means, and the reference position of the developing device holder is not detected by the reference position detecting means, An image forming apparatus that determines that the rotation of the developing device holder is abnormal . If the movement distance detected by the movement distance detection means does not reach the specified distance within a specified time after the reference position detection means detects the reference position of the developer holder, the developer holder holding The driving means is driven until the moving distance detecting means detects a moving distance larger than the moving distance corresponding to one rotation of the body, and the reference position of the developing device holder is detected by the reference position detecting means. 2. The image forming apparatus according to claim 1 , wherein if it is not performed, it is determined that the rotation of the developing device holder is abnormal . 3. Said drive means is a motor, said developing device holder is driven via a gear by the motor, the reading member, according to claim 1 or 2, characterized in that it is fixed to the rotation shaft of the motor The image forming apparatus described in 1.   When an abnormality is detected during the movement of the developing device holder, the abnormality is notified to the image data input means for inputting image data from an external device, and the movement of the developing device holder is stopped. The image forming apparatus according to any one of claims 1 to 3.   The image forming apparatus according to claim 1, further comprising a stopping unit that stops or cancels the movement of the developing device holder.   The image forming apparatus according to claim 5, wherein the stopping unit locks or unlocks the movement of the developing device holder using a solenoid.   The image forming apparatus according to claim 1, wherein the moving distance detection unit is an optical detection unit.   The image forming apparatus according to claim 1, wherein the movement distance detection unit is a magnetic detection unit. It said developing device holder is an image forming apparatus according to any one of claims 1 to 8, characterized in that to hold the at least two developing devices.

Images