Image forming apparatus and control method thereof

Abstract

To quickly start fault location specification processing that cannot be executed when a cover is not in a closed state.SOLUTION: A first type is a type in which when a cover for accessing an abnormal location enters an open state, supply of power to a load unit is cut off, the load unit operating for fault diagnosis related to the abnormal location. A CPU 212a determines the type of an abnormality that occurs this time, when a cover (front cover 125 or right cover 126) is in the open state, and if the type of this time's abnormality is the first type, executes notification processing for prompting to close the cover that is open, and starts fault diagnosis processing after the cover is closed.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that identifies the cause of an abnormality when an abnormality occurs, and a control method therefor.

Background Art

[0002] In an image forming apparatus such as a copying machine or a printer, when an operation abnormality is detected, the image forming apparatus notifies the occurrence of the abnormality by displaying an error code or transmitting it to a call center via a network. For example, as shown in FIG. 5, an error code corresponding to the detected abnormality is displayed. There may be a plurality of failure locations that cause the abnormality, such as a power supply unit, a substrate, and a mechanical mechanism. Therefore, when a service technician repairs the image forming apparatus based on the error code, it may take a lot of time to identify the failure location by sequentially checking the presence or absence of a failure in the component parts related to the error code on site. Therefore, Patent Document 1 discloses a method for identifying whether the failure location is a high-voltage power supply or a load such as a charging wire.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the failures that occur in the image forming apparatus are diverse, and there are many error codes that occur. When performing a failure diagnosis to identify the failure location corresponding to the error code, it may be necessary to operate load parts such as a motor and high voltage. 。

[0006] The present invention Even if an abnormality in the control system including the load operation unit is detected, no fault diagnosis is executed while the power supply to the load operation unit is cut off aims to

Means for Solving the Problems

[0007] An image forming apparatus for forming an image on a recording material, comprising: a cover that is opened to access the inside of the image forming apparatus, and detection means for detecting an abnormality in a control system including a load operation unit that operates to form the image; cut-off means for cutting off the power supply to the load operation unit when the cover is in an open state, control means for executing a failure diagnosis in response to the detection of the abnormality in the control system by the detection means, wherein the control means: determining whether or not the load operation unit is faulty does not execute the failure diagnosis in a state where the power supply to the load operation unit is cut off. by the cut-off means

Advantages of the Invention

[0008] According to the present invention, Even if an abnormality in the control system including the load operation unit is detected, no fault diagnosis is executed while the power supply to the load operation unit is cut off it is possible to

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

Figure 9

Figure 10

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Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus 2000 is, for example, a color image forming apparatus using an electrophotographic method. In particular, the image forming apparatus 2000 is an image forming apparatus of an intermediate transfer tandem type in which process units 101 (101y, 101m, 101c, 101k) are arranged side by side. The process units 101y, 101m, 101c, 101k form toner images of developers of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively. Note that the number of colors is not limited to four, and the order of the colors is not limited to this, either.

[0012] The image forming apparatus 2000 is composed of an image reading unit 2 and an image forming unit 3 (image forming means). A document table 4 made of a transparent glass plate is provided above the image reading unit 2. A document D placed on the document table 4 with the image surface facing downward is pressed and fixed by a document pressure plate 5. Below the document table 4, an optical system including a lamp 6 for illuminating the document D and reflecting mirrors 8, 9, 10 for guiding the optical image of the illuminated document D to the image processing unit 7 is provided. The lamp 6 and the reflecting mirrors 8, 9, 10 move at a predetermined speed to scan the document D.

[0013] In the image forming unit 3, the process units 101y, m, c, k are arranged in a substantially horizontal straight line at regular intervals on the intermediate transfer belt 108 as an image carrier. The process units 101y, m, c, k each include a photosensitive drum (photoconductor) 102y, m, c, k, a charging roller 103y, m, c, k, an exposure device 104y, m, c, k, a developing device 105y, m, c, k, and an auxiliary charging brush 109y, m, c, k. Further, toner containers 106y, m, c, k are connected to the respective developing devices 105y, m, c, k. Furthermore, the image forming unit 3 includes primary transfer rollers 107y, m, c, k corresponding to the photosensitive drums 102y, m, c, k. The image forming unit 3 also includes an intermediate transfer belt 108, a density sensor 112, a secondary transfer roller 15, a transfer cleaning device 111, and a fixing device 19.

[0014] The intermediate transfer belt 108 is rotationally driven by a driving roller 122. Each photosensitive drum 102 is rotationally driven. Each charging roller 103 uniformly charges the surface of the corresponding photosensitive drum 102. Each exposure device 104 forms an electrostatic latent image on the corresponding photosensitive drum 102 based on the signal of the sent image information. Each developing device 105 develops the electrostatic latent image formed on the corresponding photosensitive drum 102 to make it appear as a toner image. The toner image on each photosensitive drum 102 is transferred onto the intermediate transfer belt 108 (on the image carrier) by applying a predetermined pressure and an electrostatic load bias by the corresponding primary transfer roller 107.

[0015] The toner images of various colors superimposed on the intermediate transfer belt 108 are conveyed and transferred onto the sheet P, which is a recording material, on the nip where the driving roller 122 and the secondary transfer roller 15 are in contact. The residual transfer toner on the intermediate transfer belt 108 after passing through the nip portion is recovered by the transfer cleaning device 111. The sheet P is supplied from the paper cassette 18 (18a to 18d) as four storage units or the manual feed tray 50. The sheet P is stored in a stacked form in each paper cassette 18 and is fed in accordance with the image formation timing by a separation mechanism. The fed sheet P passes through a conveyance path, and after skew correction and timing correction are performed by the registration roller, it is sent to the nip portion.

[0016] A fixing device 19 is provided downstream of the nip portion. The fixing device 19 fixes the toner image on the conveyed sheet P. The sheet P on which the toner image is fixed in the fixing device 19 is discharged to the outside of the image forming apparatus 2000 by the discharge roller pair 21. The image forming apparatus 2000 includes an operation unit 1000. The operation unit 1000 has a display unit. Further, the image forming unit 3 includes a cooling rotary fan (FAN) 300. The front cover 125 is installed on the front surface of the image forming apparatus 2000 so as to be openable and closable. The user can access replaceable consumables such as the photosensitive drum 102 and the developing device 105 by opening the front cover 125. The open / closed state of the front cover 125 is detected by the front cover sensor 123.

[0017] The right cover 126 is installed on the right side surface of the image forming apparatus 2000 so as to be openable and closable. The user can access replaceable consumables such as the intermediate transfer belt 108 by opening the right cover 126, and can also access to remove the paper remaining due to a jam. The open / closed state of the right cover 126 is detected by the right cover sensor 124. The front cover 125 and the right cover 126 are provided with an interlock switch 127, and the power supply to the load operation unit is cut off by an operation of opening each cover.

[0018] Each of the paper cassettes 18 is provided with a cassette opening / closing sensor 205 for detecting opening and closing, and a size sensor (not shown) for detecting the size of the stored sheet P. When the paper cassette 18 is closed, the sheet size is automatically detected based on the output of the size sensor. Further, the manual tray 50 is provided with a manual sensor 201 for detecting the presence or absence of the sheet P on the tray. When the manual sensor 201 detects that the sheet P has been placed, a screen prompting the user to set the size of the placed sheet P is displayed on the operation unit 1000. By setting the sheet size according to the instructions on the screen, the image forming apparatus 2000 can recognize the size of the sheet P placed on the tray.

[0019] FIG. 2 is a block diagram of the control system of the image forming apparatus 2000. FIG. 3 is a control circuit diagram of the image forming apparatus 2000. This control system includes a power supply unit 200, a control unit 210, a driver unit 230, and a high voltage unit 240. These units constitute a power supply section, a signal output section, a control section, a control circuit section, and a load operation section, which will be described below.

[0020] The configuration of the power supply section will be described. The power supply section is mainly realized by the power supply unit 200. The power supply unit 200 outputs a power supply voltage of +24 [V]. The power supply unit 200 distributes the power supply voltage via fuses FU1, FU2, and FU3 and supplies power to each component. The control unit 210 steps down the +24 [V] power supply voltage supplied from the power supply unit 200 to 3.3 [V] by the DCDC converter 211 and supplies power to the CPU 212a, the driver unit 230 (ASIC 231), etc. The driver unit 230 further subdivides the +24 [V] power supply voltage supplied from the power supply unit 200 by the fuses FU4 and FU5 and supplies power to the high voltage unit 240 and the motor drive section 236 (the first motor drive section 236a and the second motor drive section 236b).

[0021] Also, the +24[V] power supply voltage is divided into two power supply systems. One of them is a power supply system whose power supply is turned on and off by an interlock switch 127 that supplies and cuts off power in conjunction with the opening and closing operations of the front cover 125 and the right cover 126. The other is a power supply system that is powered regardless of the open / closed state of the cover. In the present embodiment, the detachable motor 603 and the FAN 300 are power supply systems that are powered regardless of the open / closed state of the cover.

[0022] The control unit will be described. The control unit is mainly realized by the control unit 210. The control unit 210 controls the operations of each component and performs various control sequences related to image formation and the like by the CPU 212a executing the control program stored in the ROM 212b. At that time, the RAM 212c is used as a work memory and stores rewritable data. The RAM 212c holds, for example, high-voltage setting values for the high-voltage unit 240, drive setting information regarding detachable units, and the like. The CPU 212a is connected to the ASIC 231 of the driver unit 230 through serial communication. The CPU 212a controls the operation of the ASIC 231 by performing read / write operations on the registers inside the ASIC 231 and the RAM 212c through serial communication. Also, the CPU 212a controls the execution timing of the image output request from the user and generates information necessary for printing image output, such as the paper cassette 18 to be used and the color mode (monochrome / color) to be set, according to the request content of the image output.

[0023] The signal output unit will be described. The signal output unit is mainly implemented by the ASIC 231. The ASIC 231 includes functional modules such as an AD converter 232, a high-voltage control unit 233, and a motor control unit 234. The driver unit 230 controls a monochrome drum motor 600, a color drum motor 601, a fixing motor 602, and a detaching motor 603. The AD converter 232 captures an analog signal value. The high-voltage control unit 233 controls a high-voltage unit 240. The motor control unit 234 controls a motor drive unit 236. The ASIC 231 acquires set values from the CPU 212a through serial communication and sets each functional module based on the set values. Each functional module outputs a control signal by operating a logic circuit based on the set values.

[0024] The detaching motor 603 drives a belt detaching unit 118 (to be described later with reference to FIG. 4). The monochrome drum motor 600 drives a photosensitive drum 102k, an intermediate transfer belt 108, and a developing unit 105k. The color drum motor 601 drives photosensitive drums 102y, 102m, 102c, and developing units 105y, 105m, 105c. The fixing motor 602 drives a fixing unit 19.

[0025] The control circuit unit will be described. The control circuit unit is mainly implemented by the high-voltage unit 240 and the motor drive unit 236 in the driver unit 230. As shown in FIG. 3, the driver unit 230 further includes a signal detection unit 305 and a first current detection unit 306a. The driver unit 230 further includes a voltage detection unit 303 (a first voltage detection unit 303a and a second voltage detection unit 303b). The motor drive unit 236, the signal detection unit 305, and the first current detection unit 306a are each provided for each motor. However, in FIG. 3, only those corresponding to one detaching motor 603 are shown. As shown in FIG. 2, the first motor drive unit 236a drives the detaching motor 603. The second motor drive unit 236b drives the monochrome drum motor 600, the color drum motor 601, and the fixing motor 602. The control circuit unit operates based on the power supply from the power supply unit and the output signal from the signal output unit.

[0026] For example, the motor drive unit 236 is equipped with a driver IC as a circuit for driving the motor. When a control signal for rotating the motor is input, the driver IC controls the rotation of the motor. When the motor rotates, the photosensitive drum 102, intermediate transfer belt 108, developing device 105, fixing unit 19, belt attachment / detachment unit 118, and FAN 300, which are the load parts of the individual motors, are driven. Also, a home position sensor (HP sensor) 242 (described later in FIG. 4) provided in the belt attachment / detachment unit 118 detects the attachment / detachment position of the intermediate transfer belt 108, and the detection result is input to the ASIC 231. The input value to the ASIC 231 is notified to the CPU 212a through communication, and the CPU 212a performs position control of the belt attachment / detachment unit 118 based on the input value.

[0027] The high-voltage unit 240 includes a second current detection unit 306b and a charging DC high-voltage unit 220 (FIG. 3). The second current detection unit 306b detects the output current from the charging DC high-voltage unit 220 and sends the detection result to the ASIC 231.

[0028] The load operation unit (load unit) mainly includes the photosensitive drum 102, intermediate transfer belt 108, developing device 105, fixing unit 19, belt attachment / detachment unit 118, and FAN 300. When the motor is rotated by the motor drive unit 236, the load operation unit corresponding to each motor is driven. Note that the motor drive unit 236 is provided for each motor, but only one is shown representatively in FIG. 3.

[0029] As shown in FIG. 2, the CPU 212a is connected to the operation unit 1000 and the LAN 1001. The CPU 212a acquires an input signal such as an instruction from the operation unit 1000 and displays information corresponding to the input signal on the screen of the operation unit 1000. The CPU 212a communicates with an external device such as a computer via the LAN 1001. The output signal of the HP sensor 242 (FIG. 4) is input to the ASIC 231.

[0030] Figs. 4(a) to 4(c) are schematic views of the belt attaching / detaching unit 118. The belt attaching / detaching unit 118 switches the contact state / separation state of the intermediate transfer belt 108 and the primary transfer roller 107 with respect to the photosensitive drum 102 by the rotation of the attaching / detaching motor 603 which is a stepping motor. The home position flag (HP flag) 243 operates in conjunction with the rotation of the attaching / detaching motor 603. The three attaching / detaching positions of the intermediate transfer belt 108 are detected by the HP sensor 242.

[0031] Fig. 4(a) shows a state in which the HP sensor 242 detects the HP flag 243 and outputs ON. This state corresponds to the monochrome attaching position where the primary transfer roller 107k is in contact with the photosensitive drum 102k, and the primary transfer rollers 107y, m, c are not in contact with the photosensitive drums 102y, 102m, 102c.

[0032] Fig. 4(b) shows a state in which the HP flag 243 has advanced by the first predetermined pulse from the position (OFF position) where the HP sensor 242 no longer detects the HP flag 243. This state corresponds to the full-color attaching position where the full-color primary transfer roller 107 is in contact with the photosensitive drum 102.

[0033] Fig. 4(c) shows a state in which the HP flag 243 has advanced by the second predetermined pulse from the above OFF position of the HP flag 243. This state corresponds to the full-color detaching position where the full-color primary transfer roller 107 is not in contact with the photosensitive drum 102.

[0034] When the image forming apparatus 2000 is started up, the belt attaching / detaching unit 118 moves to the monochrome attaching position as an initialization operation. At the start of image formation, the belt attaching / detaching unit 118 moves to the monochrome attaching position when forming a monochrome image, and moves to the full-color attaching position when forming a color image. Also, when the right cover 126 is opened, the belt attaching / detaching unit 118 moves to the full-color detaching position because the intermediate transfer belt 108 may be replaced.

[0035] The density sensor 112 reads the toner images of each color superimposed on the intermediate transfer belt 108. The density sensor 112 is separated from the intermediate transfer belt 108 at the full-color removal position (Fig. 4(c)), and is in contact with or close to the intermediate transfer belt 108 at the monochrome attachment position (Fig. 4(a)) or the full-color attachment position (Fig. 4(b)).

[0036] The abnormality detection of the belt attachment / detachment unit 118 is performed as follows. When the belt attachment / detachment unit 118 transitions from the full-color attachment position or the full-color removal position to the monochrome attachment position, if the CPU 212a does not detect the ON of the HP sensor 242 within the first predetermined time, it determines that an abnormality has occurred in the belt attachment / detachment unit 118. Also, when the belt attachment / detachment unit 118 transitions from the monochrome attachment position to the full-color attachment position or the full-color removal position, if the CPU 212a does not detect the OFF of the HP sensor 242 within the second predetermined time, it determines that an abnormality has occurred in the belt attachment / detachment unit 118.

[0037] Abnormalities at various locations of the image forming apparatus 2000 are detected by sensors and the like. There are a plurality of types of abnormalities, and the first type, the second type, and the third type will be described. The first type is a type in which when a cover that is opened to access the inside of the apparatus is in the open state, the power supply to the load unit that operates for fault diagnosis regarding the abnormal location is cut off. The second type is a type in which even when a cover that is opened to access the inside of the apparatus is in the open state, the power supply to the load unit that operates for fault diagnosis regarding the abnormal location is not cut off. The second type includes the third type. The third type is a type among the second type in which there is a risk that the user may touch the load unit that operates for fault diagnosis regarding the abnormal location. Referring also to Fig. 5, examples of the types of abnormalities will be further described.

[0038] Fig. 5 is a diagram showing an example of a type data table. This type data table is a table that defines the relationship between the error code, the type of abnormality, and the content of the abnormality, and is stored in advance in the ROM 212b.

[0039] When an abnormality is detected in the image forming apparatus 2000, such as when the operation control does not end normally, the CPU 212a issues an error code. The CPU 212a notifies the error code by displaying it on the screen of the operation unit 1000 or transmitting it to the call center via the LAN 1001. For example, when an abnormality in the belt attachment / detachment unit 118 is detected, an error code "E006" is notified.

[0040] As shown in FIG. 5, '1', '2', or '3' is associated with each error code as information indicating the type of abnormality. For example, "E001" to "E004" indicating abnormalities in the developing units 105y, m, c, and k are associated with the first type '1'. "E005" indicating an abnormality in the FAN 300 is associated with the second type '2'. "E006" indicating an abnormality in the belt attachment / detachment unit 118 is associated with the third type '3'. "E007" to "E009" indicating abnormalities in the monochrome drum motor 600, color drum motor 601, and fixing motor 602 are associated with the first type '1'.

[0041] Note that the items of the abnormality detection content in the type data table (FIG. 5) are described so as to facilitate understanding of the content of the error code. Therefore, only the error code and the information indicating the abnormality type may actually be stored in the ROM 212b.

[0042] The interlock switch 127 is a cutoff means for cutting off the power supply to some load parts. For example, when the front cover 125 or the right cover 126 is in the open state, the power supply to the developing unit 105, the photosensitive drum 102, the fixing unit 19, and the high voltage unit 240 is cut off (see FIG. 2). Therefore, abnormalities in the developing unit 105, the photosensitive drum 102 (drum motors 600, 601), the fixing unit 19 (fixing motor 602), and the high voltage unit 240 fall under the first type. These load parts are load parts essential for image formation by the image forming unit 3.

[0043] On the other hand, even when the front cover 125 or the right cover 126 is in the open state, the power supply to the load parts related to the FAN 300 and the belt attachment / detachment unit 118 is not cut off, and these load parts are operable. Therefore, the abnormality of the FAN 300 and the belt attachment / detachment unit 118 falls under the second type. However, when the right cover 126 is open, there is a risk that the user may touch the load part related to the belt attachment / detachment unit 118. In order to enhance the accuracy of fault diagnosis, it is desirable to perform fault diagnosis with the right cover 126 closed so that the user does not touch the load part in the belt attachment / detachment unit 118. Therefore, the abnormality of the belt attachment / detachment unit 118 falls under the third type among the second type.

[0044] In other words, from the perspective of power supply, the first type is the type in which fault diagnosis regarding the abnormal part cannot be started unless the cover is closed. The second type is the type in which fault diagnosis regarding the abnormal part can be started even with the cover open from the perspective of power supply. The third type is the type in which fault diagnosis regarding the abnormal part cannot be started unless the cover is closed from the perspective of the accuracy of fault diagnosis.

[0045] FIG. 6 is a flowchart of the processing when an abnormality occurs. This processing is realized by the CPU 212a expanding and executing the program stored in the ROM 212b in the RAM 212c. This processing is started, for example, when the power of the image forming apparatus 2000 is turned on. In this processing, the CPU 212a serves as the determination means and the control means in the present invention.

[0046] First, the CPU 212a waits in step S101 until any abnormality is detected in the image forming apparatus 2000. When an abnormality is detected, in step S102, the CPU 212a immediately stops the image forming apparatus 2000. Note that the HP sensor 242 and the density sensor 112 cooperate with the CPU 212a to detect that an abnormality has occurred in the image forming apparatus 2000, and thus serve as the detection means in the present invention.

[0047] In step S103, the CPU 212a refers to the type data table (Figure 5) and determines the type of the abnormality that has occurred this time from the error code issued in response to the detection of an abnormality this time. For example, if the error code is "E001", the CPU 212a determines that the abnormality type is the first type. Also, if the error code is "E005", the CPU 212a determines that the abnormality type is the second type, and if the error code is "E006", the CPU 212a determines that the abnormality type is the third type.

[0048] In step S104, the CPU 212a determines whether at least one of the front cover 125 or the right cover 126 is in an open state. This is determined from the detection results of the front cover sensor 123 and the right cover sensor 124. Note that the cover to be determined whether it is in an open state is not limited to the front cover 125 or the right cover 126. That is, any cover that cuts off the power to the load unit by the interlock switch 127 when it is in an open state may be included in the determination target. As a result of the determination in step S104, if both the front cover 125 and the right cover 126 are in a closed state, the CPU 212a advances the process to step S108. On the other hand, if at least one of the front cover 125 or the right cover 126 is in an open state, the CPU 212a advances the process to step S105.

[0049] In step S105, CPU 212a determines whether the type of the current abnormality determined in step S103 is either the first type or the third type. As a result of this determination, if the type of the current abnormality is either the first type or the third type, since it is necessary to close the cover in order to perform the failure diagnosis, CPU 212a advances the process to step S106. In step S106, a notification process for prompting to close the open cover (front cover 125 or right cover 126) is executed. For example, CPU 212a causes the operation unit 1000 to display a notification screen including a message instructing to close the cover. On this notification screen, for example, in addition to an error code and a failure location being displayed in a manner similar to the screen shown in FIG. 7 described later, the above message is also displayed. Note that, including the following cases, the notification may also be by voice.

[0050] Next, in step S107, CPU 212a waits until the open cover is closed. That is, the user who has seen the above notification screen usually closes the open cover. Therefore, CPU 212a determines whether the open cover has been closed based on the detection results from the front cover sensor 123 and the right cover sensor 124. Note that the front cover sensor 123 and the right cover sensor 124 cooperate with CPU 212a to acquire the open / closed state of the cover, and thus play a role as the acquisition means in the present invention. When the open cover has been closed, CPU 212a advances the process to step S108.

[0051] On the other hand, as a result of the determination in step S104, if the type of the current abnormality is the second type, since the failure diagnosis can be started without closing the cover, the process advances to step S108. In step S108, CPU 212a executes a failure diagnosis process (described later with reference to FIGS. 10 to 12). Note that as the failure diagnosis process, one corresponding to the current abnormality location is executed. For example, FIGS. 10, 11, and 12 show failure diagnosis processes corresponding to abnormalities of the developing device 105, FAN 300, and the belt attachment / detachment unit 118, respectively.

[0052] FIG. 7 and FIG. 8 are diagrams showing examples of notification screens displayed on the operation unit 1000. In step S109, the CPU 212a determines whether the failure location has been specified by the failure diagnosis process in step S108. If the failure location has been specified, the CPU 212a proceeds to step S111 and, as shown in FIG. 7, notifies the specified failure location. At this time, the error code and the specific name of the failure location are also displayed. On the other hand, if the failure location has not been specified, the CPU 212a determines in step S110 that the failure location cannot be specified and proceeds with the process to step S111. In step S111, which is transitioned from step S110, the CPU 212a notifies, as shown in FIG. 8, the error code and a "-" indicating that the failure location could not be specified. The user can understand from the error code that an abnormality has been detected but the specific failure location could not be specified. After step S111, the CPU 212a ends the process shown in FIG. 6.

[0053] FIG. 9 is a diagram showing an example of an electrical failure diagnosis table. The electrical failure diagnosis table is stored in the ROM 212b. In the electrical failure diagnosis table, diagnostic targets such as motors and DC outputs, and the corresponding power supply unit, signal output unit, control circuit unit, and load operation unit are defined. This electrical failure diagnosis table is mainly used in the electrical failure diagnosis process (FIGS. 13 and 14) described later.

[0054] FIG. 10 is a flowchart of the failure diagnosis process executed in step S108 of FIG. 6. This process is a failure diagnosis process particularly executed when the abnormal location is the developing unit 105.

[0055] First, in step S201, the CPU 212a issues a command to start driving the developing device 105 and waits until the driving of the developing device 105 is started. Then, when the driving of the developing device 105 is started, the CPU 212a starts the abnormality detection process of the developing device 105 and determines whether an abnormality of the developing device 105 has been detected in step S202. Here, the abnormality detection process is performed by periodically monitoring the reading value of a toner concentration sensor (not shown) provided in the developing device 105. When the reading value of the toner concentration deviates from the predetermined range, it is detected that an abnormality has occurred in the developing device 105.

[0056] As a result of the determination in step S202, if no abnormality of the developing device 105 is detected, the CPU 212a determines whether the driving of the developing device 105 has been stopped in step S203. Note that the driving duration from the start of driving of the developing device 105 is predetermined. Then, if the driving of the developing device 105 is not stopped, the CPU 212a returns the process to step S202, and if the driving of the developing device 105 is stopped, since no abnormality of the developing device 105 has been detected, the process shown in FIG. 10 is terminated. Therefore, when an abnormality of the developing device 105 is detected before the driving of the developing device 105 is stopped, the CPU 212a proceeds to step S204.

[0057] In step S101 of FIG. 6 described above, since the processes corresponding to steps S201 to S203 are executed, in FIG. 10, the processes of steps S201 to S203 may be omitted.

[0058] In step S204, the CPU 212a causes the image forming apparatus 2000 to stop urgently and executes start processing for electrical fault diagnosis regarding the developing device 105. Here, diagnosis of the charging DC high voltage output and the developing DC high voltage output is started. In step S205, the CPU 212a starts preparatory operations of the image forming unit 3 such as the photosensitive drum 102 and the intermediate transfer belt 108 that are necessary for high voltage output. When the preparatory operations of the image forming unit 3 are completed and it becomes a state where high voltage can be applied, the CPU 212a executes an electrical fault diagnosis process in step S206. Here, the electrical fault diagnosis process shown in FIG. 14 is executed (described later).

[0059] In step S207, the CPU 212a determines whether or not it can identify the failure location as a result of the electrical fault diagnosis process. Then, if the CPU 212a can identify the failure location, it ends the process shown in FIG. 10. In this case, in step S111 of FIG. 6, the identified failure location is notified as a result of the electrical fault diagnosis process. On the other hand, if the failure location cannot be identified as a result of the electrical fault diagnosis process, it is determined that the charging DC high voltage output and the developing DC high voltage output are normal, and the cause of the abnormality is not that toner or magnetic carrier was discharged from the developing device 105 due to an abnormality in the high voltage output. Therefore, the CPU 212a identifies that the developing device 105 or the exposure device 104 has failed in step S208 and ends the process shown in FIG. 10. In this case, in step S111 of FIG. 6, the failure location identified in step S208 is notified.

[0060] Note that the load units that need to operate for the fault diagnosis process of the developing device 105 are the drum motors 600 and 601, the high voltage unit 240, etc. Since these are power supply systems in which power is not supplied (cut off) by the interlock switch 127, the fault diagnosis cannot be executed unless the cover is closed (the first type). As shown in FIG. 10, in the fault diagnosis process of the developing device 105, an electrical fault diagnosis is executed, but a load fault diagnosis (processing corresponding to steps S407 to S412 in FIG. 12 described later) is not executed.

[0061] FIG. 11 is a flowchart of the failure diagnosis process executed in step S108 of FIG. 6. This process is a failure diagnosis process that is particularly executed when the abnormal location is FAN300.

[0062] First, in step S301, CPU 212a issues a command to start driving FAN300 and waits until the driving of FAN300 is started. Then, when the driving of FAN300 is started, in step S302, CPU 212a starts the abnormality detection process of FAN300 and determines whether an abnormality of FAN300 has been detected. Here, the abnormality detection process is performed by periodically monitoring the lock signal input from FAN300. The lock signal is a signal indicating whether FAN300 is rotating or stopped. When the lock signal does not indicate the rotating state even after the elapse of the third predetermined time from the start of driving FAN300, or when it indicates the rotating state and then continues to indicate the stopped state for the fourth predetermined time, it is detected that an abnormality has occurred in FAN300.

[0063] As a result of the determination in step S302, when no abnormality of FAN300 is detected, CPU 212a determines in step S303 whether the driving of FAN300 has stopped. Note that the driving duration from the start of driving FAN300 is predetermined. Then, when the driving of FAN300 has not stopped, CPU 212a returns the process to step S302, and when the driving of FAN300 has stopped, since no abnormality of FAN300 has been detected, the process shown in FIG. 11 is terminated. Therefore, when an abnormality of FAN300 is detected before the driving of FAN300 stops, CPU 212a advances the process to step S304.

[0064] Note that in step S101 of FIG. 6 described above, the processes corresponding to steps S301 to S303 have been executed. Therefore, in FIG. 11, the processes of steps S301 to S303 may be omitted.

[0065] In step S304, the CPU 212a causes the image forming apparatus 2000 to perform an emergency stop and executes start processing for electrical fault diagnosis regarding the FAN 300. In step S305, electrical fault diagnosis processing is executed. Here, the electrical fault diagnosis processing shown in FIG. 13 is executed (described later).

[0066] In step S306, the CPU 212a determines whether or not it has been able to identify the location of a fault as a result of the electrical fault diagnosis processing. Then, if the CPU 212a has been able to identify the location of the fault, it ends the processing shown in FIG. 11. In this case, in step S111 of FIG. 6, the identified location of the fault is notified as a result of the electrical fault diagnosis processing. On the other hand, if the location of the fault could not be identified as a result of the electrical fault diagnosis processing, it is identified that the FAN 300 is faulty, and the processing shown in FIG. 11 is ended. In this case, in step S111 of FIG. 6, the location of the fault identified in step S307 is notified.

[0067] Note that the load unit (FAN motor) that needs to operate for the fault diagnosis processing of the FAN 300 is a power supply system in which power supply is not cut off by the interlock switch 127, so that fault diagnosis can be executed even when the cover is open (second type). In the fault diagnosis processing of the FAN 300, electrical fault diagnosis is executed, but load fault diagnosis (processing corresponding to steps S407 to S412 in FIG. 12 described later) is not executed.

[0068] FIG. 12 is a flowchart of the fault diagnosis processing executed in step S108 of FIG. 6. This processing is, in particular, fault diagnosis processing executed when the abnormal location is the belt attachment / detachment unit 118.

[0069] First, in step S401, the CPU 212a issues a command to start the initialization operation and the attachment / detachment position change operation of the belt attachment / detachment unit 118, and waits until these operations are started. Then, when the initialization operation and the attachment / detachment position change operation of the belt attachment / detachment unit 118 are started, in step S402, the CPU 212a starts the abnormality detection process of the belt attachment / detachment unit 118 and determines whether an abnormality of the belt attachment / detachment unit 118 has been detected. Here, if the initialization operation or the attachment / detachment position change operation is not completed even after the fifth predetermined time has elapsed since the operation of the belt attachment / detachment unit 118 was started by the attachment / detachment motor 603, it is detected that an abnormality has occurred in the belt attachment / detachment unit 118.

[0070] As a result of the determination in step S402, if no abnormality of the belt attachment / detachment unit 118 is detected, the CPU 212a determines in step S403 whether the drive of the belt attachment / detachment unit 118 has been stopped. Note that the drive continuation period from the start of driving of the belt attachment / detachment unit 118 is predetermined. Then, if the drive of the belt attachment / detachment unit 118 is not stopped, the CPU 212a returns the process to step S402, and if the drive of the belt attachment / detachment unit 118 is stopped, since no abnormality of the belt attachment / detachment unit 118 has been detected, the process shown in FIG. 12 is terminated. Therefore, when an abnormality of the belt attachment / detachment unit 118 is detected before the drive of the belt attachment / detachment unit 118 is stopped, the CPU 212a advances the process to step S404.

[0071] Note that in step S101 of FIG. 6 described above, since the processes corresponding to steps S401 to S403 are executed, in FIG. 12, the processes of steps S401 to S403 may be omitted.

[0072] In step S404, the CPU 212a causes the image forming apparatus 2000 to stop urgently and executes the start process of the electrical fault diagnosis regarding the belt attachment / detachment unit 118. In step S405, the electrical fault diagnosis process is executed. Here, the electrical fault diagnosis process shown in FIG. 13 is executed (described later).

[0073] In step S406, the CPU 212a determines whether it can identify the location of a failure as a result of the electrical failure diagnosis process. If the CPU 212a can identify the location of the failure, it ends the process shown in FIG. 12. In this case, in step S111 of FIG. 6, the identified location of the failure is notified as a result of the electrical failure diagnosis process. On the other hand, if it cannot identify the location of the failure as a result of the electrical failure diagnosis process, it executes the load failure diagnosis process after step S407.

[0074] The CPU 212a starts the load unit failure diagnosis in step S407, starts driving the attachment / detachment motor 603 in step S408, and starts reading by the density sensor 112 in step S409. In step S410, the CPU 212a determines whether there is a change in the reading value by the density sensor 112. Here, by starting the drive of the attachment / detachment motor 603, the attachment / detachment position changes, and by the change in the attachment / detachment position, the positional relationship between the density sensor 112 and the intermediate transfer belt 108 also changes. Therefore, if the attachment / detachment position is switched normally, there is a difference in the reading value of the density sensor 112 between the full-color detachment position and the monochrome attachment position / full-color attachment position. Thus, the CPU 212a samples the reading value of the density sensor 112 for a sixth predetermined time and determines whether the reading value has changed by a predetermined value or more.

[0075] If there is a change in the reading value, it can be determined that the attachment / detachment operation is being performed but the HP sensor 242 does not respond. Therefore, the CPU 212a identifies that the location of the failure is the HP sensor 242 in step S411. On the other hand, if there is no change in the reading value, it can be determined that the attachment / detachment operation is not being performed. Therefore, the CPU 212a identifies that the location of the failure is the drive transmission mechanism such as gears related to the belt attachment / detachment unit 118 in step S412. After steps S411 and S412, the CPU 212a ends the process shown in FIG. 12. In this case, in step S111 of FIG. 6, the location of the failure identified in step S411 or S412 is notified.

[0076] Note that the detachable motor 603 to be diagnosed is a power supply system in which power supply is not cut off by the interlock switch 127, so the failure diagnosis can be executed even when the cover is open. However, from the viewpoint of the accuracy of the failure diagnosis, the failure diagnosis cannot be started unless the cover is closed (the third type). In the failure diagnosis process of the belt detachment unit 118, not only the electrical failure diagnosis but also the load failure diagnosis is executed.

[0077] FIG. 13 is a flowchart of the electrical failure diagnosis process executed in step S305 of FIG. 11 or step S405 of FIG. 12. In FIG. 13, the electrical components related to the drive of the detachable motor 603 will be described as an example. FIGS. 2 and 3 are also referred to as appropriate.

[0078] First, in step S501, the CPU 212a determines the failure of the power supply unit, and in step S502, determines whether the power supply unit has failed. Then, if the power supply unit has failed, the CPU 212a proceeds to step S503, and if the power supply unit has not failed, the CPU 212a proceeds to step S506. In step S503, the CPU 212a determines whether the power supply unit 200 has failed. If the power supply unit 200 has failed, the process proceeds to step S504, and if the power supply unit 200 has not failed, the process proceeds to step S505.

[0079] Specifically, in steps S501 to S503, the CPU 212a determines the failure of the power supply unit as follows. According to the electrical failure diagnosis table (FIG. 9), the power supply unit that supplies power to the detachable motor 603 is +24V_B_FU. Therefore, the CPU 212a checks the output of the +24V_B_FU power supply. For this purpose, the first voltage detection unit 303a of the driver unit 230 detects whether the voltage of +24V_B before passing through the fuse FU5 is equal to or higher than the first threshold value th1. Here, it is assumed that the first threshold value th1 is 18 [V].

[0080] The detection result by the first voltage detector 303a is transmitted to the CPU 212a via the ASIC 231. The CPU 212a determines the failure location according to the detection result of the first voltage detector 303a. When the detection result indicates that the voltage of +24V_B is less than the first threshold th1, the CPU 212a determines that the output of the power supply unit (power supply unit 200) is abnormal. That is, the CPU 212a determines that the path (fuse FU3) for outputting the voltage of +24V_B of the power supply unit 200 is the failure location. In this case, the CPU 212a identifies that the failed component is the power supply unit 200.

[0081] When the voltage of +24V_B is normal, the second voltage detector 303b of the driver unit 230 detects whether the voltage of +24V_B_FU passing through the fuse FU5 is greater than or equal to the second threshold th2. The second threshold th2 is, for example, the same value as the first threshold th1. The second voltage detector 303b performs the detection process in the same manner as the first voltage detector 303a and transmits the detection result to the CPU 212a via the ASIC 231. The CPU 212a determines whether the voltage of +24V_B_FU is normal according to the detection result of the second voltage detector 303b. That is, when the voltage of +24V_B_FU is less than the second threshold th2, the CPU 212a determines that the voltage of +24V_B_FU is abnormal. When the CPU 212a determines that the voltage of +24V_B_FU is abnormal, it determines that the failure location is the fuse FU5. In this case, the CPU 212a identifies that the failed component is the driver unit 230. When the CPU 212a determines that both the voltages of +24V_B and +24V_B_FU are normal (the voltage of +24V_B ≥ the first threshold th1 holds and the voltage of +24V_B_FU ≥ the second threshold th2 holds), it determines that the power supply unit is normal.

[0082] Summarizing the above, it is as follows. If the result of the determination in step S502 is that neither the voltage of +24V_B ≥ the first threshold value th1 nor the voltage of +24V_B_FU ≥ the second threshold value th2 holds, the CPU212a proceeds with the process to step S503. If the voltage of +24V_B ≥ the first threshold value th1 holds and the voltage of +24V_B_FU ≥ the second threshold value th2 holds, the CPU212a determines that the power supply unit is normal and proceeds with the process to step S506.

[0083] In step S503, the CPU212a determines whether the power supply unit 200 is faulty. If the voltage of +24V_B < the first threshold value th1 holds, the CPU212a proceeds to step S504 and identifies that the faulty location is the power supply unit 200. Also, if the voltage of +24V_B ≥ the first threshold value th1 holds and the voltage of +24V_B_FU < the second threshold value th2 holds, the CPU212a proceeds to step S505 and identifies that the faulty location is the driver unit 230.

[0084] Next, in step S506, the CPU212a performs a failure determination of the signal output unit, and in step S507, determines whether the signal output unit is faulty. Then, if the signal output unit is faulty, the CPU212a proceeds with the process to step S505, and if the signal output unit is not faulty, the CPU212a proceeds with the process to step S508.

[0085] Specifically, in steps S506 and S507, the CPU212a performs a failure determination of the signal output unit as follows. The CPU212a checks the motor control signal transmitted from the motor control unit 234 of the ASIC231 to the first motor drive unit 236a for determining the faulty location of the signal output unit. The motor control signal includes signals such as the rotation direction, speed, and drive mode of the motor. The CPU212a obtains from the electrical failure diagnosis table (Figure 9) that the motor control signal of the signal output unit of the detachable motor 603 is the detachable motor control signal. The CPU212a sets the ASIC231 so that the detachable motor control signal is output at a high level.

[0086] The signal detection unit 305 of the driver unit 230 compares the attachment / detachment motor control signal with a third threshold value th3. The third threshold value th3 is set to 2.8 [V]. The comparison result by the signal detection unit 305 is transmitted to the CPU 212a via the ASIC 231. The CPU 212a checks the output state according to the comparison result by the signal detection unit 305. When the comparison result indicates that the attachment / detachment motor control signal is equal to or greater than the third threshold value th3, the CPU 212a tentatively determines that the attachment / detachment motor control signal is normal. When the comparison result indicates that the attachment / detachment motor control signal is less than the third threshold value th3, the CPU 212a determines that the attachment / detachment motor control signal is abnormal. When the CPU 212a determines that the attachment / detachment motor control signal is abnormal, it identifies that the faulty location is the motor control unit 234. In this case, the CPU 212a identifies that the faulty component is the driver unit 230.

[0087] Next, the CPU 212a sets the ASIC 231 so that the attachment / detachment motor control signal is output at a low level. The signal detection unit 305 checks the attachment / detachment motor control signal by comparing it with a fourth threshold value th4. The fourth threshold value th4 is set to 0.8 [V]. The comparison result by the signal detection unit 305 is transmitted to the CPU 212a via the ASIC 231. The CPU 212a checks the output state according to the comparison result by the signal detection unit 305. When the comparison result indicates that the attachment / detachment motor control signal is less than the fourth threshold value th4, the CPU 212a tentatively determines that the attachment / detachment motor control signal is normal. When the comparison result indicates that the attachment / detachment motor control signal is equal to or greater than the fourth threshold value th4, the CPU 212a determines that the attachment / detachment motor control signal is abnormal. When the CPU 212a determines that the attachment / detachment motor control signal is abnormal, it identifies that the faulty location is the motor control unit 234. In this case, the CPU 212a identifies that the faulty component is the driver unit 230.

[0088] When the CPU 212a outputs a high-level attachment / detachment motor control signal or a low-level attachment / detachment motor control signal, if it tentatively determines that the attachment / detachment motor control signal is normal in either case, it determines that the attachment / detachment motor control signal is normal.

[0089] Summarizing the above, it is as follows. When the discrimination result in step S507 is that the high-level attachment / detachment motor control signal < th3 or the low-level attachment / detachment motor control signal ≥ th4 holds, the CPU 212a determines that the attachment / detachment motor control signal is abnormal. Therefore, in step S505, the CPU 212a specifies that the failure location is the motor control unit 234 and the failure location is the driver unit 230 (S505). On the other hand, when the high-level attachment / detachment motor control signal ≥ th3 and the low-level attachment / detachment motor control signal < th4 hold, the CPU 212a determines that the attachment / detachment motor control signal is normal and the signal output unit is not faulty. In this case, the CPU 212a advances the process to step S508.

[0090] Next, in step S508, the CPU 212a performs a failure determination of the control circuit unit, and in step S509, determines whether the control circuit unit is faulty. Then, when the control circuit unit is faulty, the CPU 212a advances the process to step S505, and when the control circuit unit is not faulty, the CPU 212a advances the process to step S510.

[0091] In the failure determination of the control circuit unit (S508), the CPU 212a obtains from the electrical failure diagnosis table (Figure 9) that the control circuit unit of the attachment / detachment motor 603 is the first motor drive unit 236a. The CPU 212a sets the first motor drive unit 236a of the ASIC 231 to operate the attachment / detachment motor 603. A motor control signal is output from the signal output unit and input to the first motor drive unit 236a. In a state where power and signals are input to the control circuit unit in this way, the first current detection unit 306a detects the output current from the control circuit unit.

[0092] The first current detection unit 306a detects whether the current flowing from the first motor drive unit 236a to the detachable motor 603 is equal to or greater than a fifth threshold value th5. The fifth threshold value th5 is set to 100 [mA]. The detection result by the first current detection unit 306a is transmitted to the CPU 212a via the ASIC 231. The CPU 212a determines the failure location according to the detection result by the first current detection unit 306a. When the detection result indicates that the current flowing through the detachable motor 603 is equal to or greater than the fifth threshold value th5, the CPU 212a determines that the first motor drive unit 236a is normal. When the detection result indicates that the current flowing through the detachable motor 603 is less than the fifth threshold value th5, the CPU 212a determines that the first motor drive unit 236a is abnormal. When the CPU 212a determines that the first motor drive unit 236a is abnormal, it identifies that the failure location is the control circuit unit. That is, when the detection result indicates that the current flowing through the detachable motor 603 is less than the fifth threshold value th5, the CPU 212a identifies that the failed component is the driver unit 230 (S505). When the control circuit unit is normal, the CPU 212a determines that the electrical component to be diagnosed is not faulty (S510).

[0093] In addition, the electrical fault diagnosis of the monochrome drum motor 600, the color drum motor 601, the fixing motor 602, and the FAN 300 is also executed in the same manner as the detachable motor 603. At this time, the CPU 212a acquires the power supply unit, the signal output unit, and the control circuit unit to be diagnosed from the electrical fault diagnosis table (Fig. 9).

[0094] In this way, in step S504, the CPU 212a identifies that the failed component is the power supply unit 200, in step S505, the CPU 212a identifies that the failed component is the driver unit 230, and in step S510, the CPU 212a determines that there is no fault in the electrical component to be diagnosed. After steps S504, S505, and S510, the CPU 212a ends the process shown in Fig. 13.

[0095] Fig. 14 is a flowchart of the electrical fault diagnosis process executed in step S206 of Fig. 10. In Fig. 14, the electrical components related to the charged DC output are taken as an example for explanation.

[0096] The processes of steps S601 to S605 are the same as the processes of steps S501 to S505 in FIG. 13. However, according to the electrical fault diagnosis table (FIG. 9), the power supply unit corresponding to the charged DC output is +24V_A_FU. Therefore, the CPU212a checks the output of the +24V_A_FU power supply. Based on the detection result by the second voltage detection unit 303b, the CPU212a performs an output check in the same manner as in steps S501 to S503, and identifies whether the fault location is the power supply unit 200 (S604) or the driver unit 230 (S605).

[0097] Summarizing the above, it is as follows. If either the voltage of +24V_A < the first threshold th1 or the voltage of +24V_A_FU < the second threshold th2 does not hold as a result of the determination in step S602, the CPU212a proceeds to step S603. If the voltage of +24V_A ≥ the first threshold th1 holds and the voltage of +24V_A_FU ≥ the second threshold th2 holds, the CPU212a determines that the power supply unit is normal and proceeds to step S606.

[0098] In step S603, the CPU212a determines whether the power supply unit 200 is faulty. If the voltage of +24V_A < the first threshold th1 holds, the CPU212a proceeds to step S604 and identifies that the fault location is the power supply unit 200. Also, if the voltage of +24V_A ≥ the first threshold th1 holds and the voltage of +24V_A_FU < the second threshold th2 holds, the CPU212a proceeds to step S605 and identifies that the fault location is the driver unit 230.

[0099] In steps S606 and S607, the CPU 212a executes a failure determination process for the signal output unit similar to that in steps S506 and S507 of FIG. 13. However, the CPU 212a obtains from the electrical failure diagnosis table (FIG. 9) that the signal output unit of the charged DC output is a charged DC high-voltage control signal. Therefore, the CPU 212a checks the charged DC high-voltage control signal from the high-voltage control unit 233 of the ASIC 231 to the high-voltage unit 240 for determining the failure location of the signal output unit. This charged DC high-voltage control signal includes signals such as an output voltage setting signal and a clock for driving the transformer.

[0100] The CPU 212a checks the charged DC high-voltage control signal when it is set to be output at a high level and a low level. The charged DC high-voltage control signal is compared with a third threshold value th3 and a fourth threshold value th4.

[0101] Summarizing the above, the following is obtained. If, as a result of the determination in step S607, the high-level charged DC high-voltage control signal < th3 or the low-level charged DC high-voltage control signal ≥ th4 holds, the CPU 212a determines that the charged DC high-voltage control signal is abnormal. Therefore, in step S605, the CPU 212a specifies that the failure location is the motor control unit 234 and the failure location is the driver unit 230 (S605). On the other hand, if the high-level charged DC high-voltage control signal ≥ th3 and the low-level charged DC high-voltage control signal < th4 hold, the CPU 212a determines that the charged DC high-voltage control signal is normal and the signal output unit is not faulty. In this case, the CPU 212a proceeds with the process to step S608.

[0102] Next, in step S608, the CPU 212a performs a failure determination of the control circuit unit, and in step S609, determines whether the control circuit unit has failed. Then, if the control circuit unit has not failed, the CPU 212a proceeds to step S610 and determines that there is no failure in the electrical component to be diagnosed. However, if the control circuit unit has failed, the CPU 212a identifies in step S611 that it is a failure of the high-voltage unit 240 (S611). This is because the high-voltage control circuit related to the charged DC high-voltage output is mounted in the high-voltage unit 240.

[0103] In the failure determination of the control circuit unit (S608), the CPU 212a obtains from the electrical failure diagnosis table (Fig. 9) that the control circuit unit of the charged DC high-voltage output is the charged DC high-voltage section 220, and checks the output of the charged DC high-voltage section 220. For this purpose, the CPU 212a sets the high-voltage control section 233 of the ASIC 231 to output -1000V. At this time, the second current detection section 306b detects the output current from the charged DC high-voltage section 220. If the current value detected by the second current detection section 306b is 20uA or less, the CPU 212a determines that there is an output abnormality in the charged DC high-voltage section 220. In this case, the CPU 212a identifies that it is a failure of the high-voltage unit 240 (S611). If the detected current value exceeds 20uA, the CPU 212a determines that the high-voltage unit 240 has not failed (S610). After steps S604, S605, S610, and S611, the CPU 212a ends the process shown in Fig. 14.

[0104] The failure diagnosis process of the electrical components related to the high voltages of the developing DC output, primary transfer DC output, and secondary transfer DC output is also executed in the same manner as the charged DC high-voltage output. At that time, the CPU 212a obtains the power supply section, signal output section, and control circuit section to be diagnosed from the electrical failure diagnosis table (Fig. 9). Note that the signal detection section 305, the second current detection section 306b, and the motor drive section 236 are provided for each individual high-voltage output. By the same process as the process shown in Fig. 14, the failure locations of the power supply unit 200, driver unit 230, and high-voltage unit 240 related to each high voltage are identified.

[0105] According to this embodiment, when an abnormality is detected and the cover is in the open state, if the type of the abnormality is the first type, the CPU 212a notifies that the cover is to be closed and starts a failure diagnosis after the cover becomes closed (S107). Thereby, it is possible to quickly start the specific process for identifying the failure location that cannot be carried out unless the cover is closed.

[0106] Also, when an abnormality is detected and the cover is in the open state, if the type of the abnormality is the second type, the CPU 212a starts a failure diagnosis without notifying that the cover is to be closed and with the cover remaining in the open state (S105 → S108). Thereby, it is possible to quickly start the specific process for identifying the failure location that can be carried out even when the cover is open.

[0107] Also, when an abnormality is detected and the cover is in the open state, if the type of the abnormality is the third type, the CPU 212a notifies that the cover is to be closed and starts a failure diagnosis after the cover becomes closed (S107). Thereby, the accuracy of identifying the failure location can be improved.

[0108] Note that the shut-off means for shutting off the power supply to some of the load parts when the cover is closed is not limited to the configuration such as the interlock switch 127.

[0109] As described above, the present invention has been described in detail based on its preferred embodiments. However, the present invention is not limited to these specific embodiments, and various forms within the scope not departing from the gist of the present invention are also included in the present invention.

Explanation of Reference Numerals

[0110] 3 Image forming unit 112 Density sensor 123 Front cover sensor 124 Right cover sensor 125 Front cover 126 Right cover 127 Interlock switch 212a CPU 242 HP sensor 2000 Image forming apparatus

Claims

1. An image forming apparatus for forming an image on a recording material, a cover that can be opened to access the interior of the image forming apparatus; a detection means for detecting an abnormality in a control system including a load operating unit that operates to form the image; a cut-off means for cutting off the power supply to the load operating unit when the cover is in an open state; a control means for executing a fault diagnosis to determine whether or not the load operation unit has a fault in response to the detection of an abnormality in the control system by the detection means, The image forming apparatus according to claim 1, wherein the control unit does not execute the fault diagnosis in a state in which the power supply to the load operating unit is cut off by the cutoff unit.

2. The control means, in response to the detection of an abnormality in the control system by the detection means, identifies a fault location in the control system, 2. The image forming apparatus according to claim 1, wherein the fault diagnosis includes a process of outputting information about the identified fault location.

3. The control means, in response to the detection of an abnormality in the control system by the detection means, identifies a fault location in the control system, a display unit for displaying information about a fault location identified by the fault diagnosis; 2. The image forming apparatus according to claim 1, wherein the fault diagnosis includes a process of displaying the information relating to the identified fault location on the display means.

4. A photoconductor on which an electrostatic latent image is formed; a developing unit for developing the electrostatic latent image on the photoconductor, 2. The image forming apparatus according to claim 1, wherein the load operating section is the developing means.

5. The device further includes a notification means for issuing a notification to prompt the user to close the cover if the cover is open when an abnormality in the control system is detected by the detection means, 2. The image forming apparatus according to claim 1, wherein the control unit, when the notification is made by the notification unit, executes the fault diagnosis after the cover is closed.

6. The image forming apparatus described in Claim 1, characterized in that the control means performs electrical fault diagnosis to identify a fault location other than the load operating unit included in the control system without operating the load operating unit, even when the power supply to the load operating unit is cut off by the cutting means.

7. a load operating section that operates to form an image on a recording material; a cover that can be opened to access the inside of the image forming apparatus; a cut-off unit that cuts off power supply to the load operation unit when the cover is in an open state, Detecting an abnormality in a control system including the load operation unit; In response to the detection of an abnormality in the control system, a fault diagnosis is performed to determine whether or not the load operation unit has a fault; The method for controlling an image forming apparatus, wherein the fault diagnosis is not performed in a state in which the power supply to the load operating unit is cut off by the cutoff unit.

8. In response to detection of an abnormality in the control system, identifying a fault location in the control system; 8. The method for controlling an image forming apparatus according to claim 7, wherein the fault diagnosis includes a process for outputting information on the identified fault location.

9. In response to detection of an abnormality in the control system, identifying a fault location in the control system; 8. The method according to claim 7, wherein the fault diagnosis includes a process for displaying information about the identified fault location.

10. When an abnormality in the control system is detected, if the cover is open, a notification is given to prompt the user to close the cover; 8. The method for controlling an image forming apparatus according to claim 7, wherein, when the notification is made, the fault diagnosis is executed after the cover is closed.

11. A control method for an image forming apparatus as described in Claim 7, characterized in that even when the power supply to the load operating unit is cut off by the cutting means, an electrical fault diagnosis is performed to identify a fault location other than the load operating unit included in the control system without operating the load operating unit.

Images