JP2013222136A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing a time for a sub CPU to return to a normal operation state from a runaway state.SOLUTION: After a sub CPU 203 starts runaway, and a main CPU 201 detects the runaway of the sub CPU 203, the main CPU 201 resets the sub CPU 203 and subsequently performs recovery control. The sub CPU 203 performs downloading of firmware after the reset. When the sub CPU 203 completes downloading the firmware and is returned to a normal operation state, and the main CPU 201 completes the recovery control, an image forming apparatus 1 returns to a normal operation.

Description

  The present invention relates to an image forming apparatus, and more particularly to a technique for shortening a recovery time from a system failure.

  In an image forming apparatus, a microprocessor is mounted because input / output processing, image processing, image formation control processing, and the like need to be executed. Specifically, the processing load is heavy as in high-resolution image processing, but the controller control processor executes non-real-time processing that does not have strict processing timing constraints, and processing such as recording sheet transport processing in image formation In general, a separate engine control processor that executes real-time processing that requires a light processing load but a strict processing timing is provided.

  In this way, it is possible to avoid the processing speed from being lowered by waiting for the real-time processing by the non-real-time processing, or conversely losing the processing timing by being disturbed by the non-real-time processing, Both the processing speed that does not give stress to the user and the smoothness of the image processing are ensured. Further, when a plurality of processors are used in combination, it is effective to integrate these into one chip to form an SOC (System On a Chip) because both the device scale and the manufacturing cost can be reduced.

  In a system equipped with a plurality of CPUs (Central Processing Units), the main CPU that manages the operation of the entire system often monitors the operating states of other CPUs (sub CPUs) constituting the system, and image formation is performed. In the apparatus, the controller control processor responsible for non-real time processing is used as a main CPU, and the operation state of the engine control processor responsible for real time processing is monitored. When the main CPU detects that the engine control processor is running out of control for some reason, the main CPU resets (restarts) the engine control processor to normalize the operation state.

  In this way, the time required for normalizing the operation state can be shortened by re-turning on the power supply of the image forming apparatus as compared with the case where the entire apparatus is restarted. Further, the main CPU automatically resets the sub CPU without any user operation, so that the user's hand is not bothered.

JP-A-6-119210 JP 2000-326591 A JP 2011-8561 A

However, if the engine control processor runs out of control during image formation, the main CPU detects the runaway and resets the engine control processor, and the image forming process is interrupted until the engine control processor starts up again. The interruption of the image forming process has a particularly great influence on the user's convenience, so the waiting time due to the interruption must be reduced a little.
Further, the image forming apparatus executes an image stabilization process in order to prevent image quality deterioration due to a change in environmental conditions or the like. Even when the engine control processor runs out of control during the image stabilization process, the image formation process may be delayed depending on the execution timing of the image stabilization process, which may reduce the convenience for the user. For this reason, it is desired that the engine control processor quickly recovers to normal even when the engine control processor goes out of control during the image stabilization process.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of shortening the time from when a sub CPU goes out of control to return to normal operation. And

  In order to achieve the above object, an image forming apparatus according to the present invention includes a peripheral device having a conveyance unit that conveys a recording sheet, and a transfer unit that transfers a toner image to the recording sheet, and the peripheral device by non-real-time control. A first CPU for controlling the peripheral device, a second CPU for controlling the peripheral device by real-time control, and a runaway detecting means for detecting a runaway of the second CPU, wherein the first CPU When the second CPU is controlling the peripheral device and the runaway detection means detects the runaway of the second CPU, the second CPU is reset and prior to the completion of the reset of the second CPU. Then, recovery control for returning the peripheral device to a normal state is started.

  In this case, the recovery control for returning the peripheral device to the normal state is started by the first CPU prior to the completion of the reset of the second CPU. The image forming apparatus can be returned to the normal state by completing the recovery control earlier than the prior art in which the second CPU performs the recovery control. Therefore, when the second CPU goes out of control, the waiting time of the user of the image forming apparatus can be shortened to contribute to the convenience.

In this case, the recovery control may be a control for discharging the recording sheet remaining on the transport path of the transport unit to the outside by the second CPU running away during image formation. In this way, even if the second CPU runs out of control during image formation, the remaining sheet can be discharged earlier, so that the normal state can be restored earlier.
The second CPU includes a conveyance stop unit that detects a paper jam on the conveyance path and stops conveyance of the recording sheet by the conveyance unit, and the first CPU performs the conveyance stop. If the recovery control is started after prohibiting the conveyance stop by the means, the recording sheet can be discharged without being interrupted by the conveyance stop means.

  Further, it is impossible to discharge the recording sheet by the discharge enable / disable determining unit that determines whether or not the recording sheet remaining on the transport path can be discharged outside the apparatus, and the discharge enable / disable determining unit. If it is determined that the paper is jammed, the recovery control is prohibited and the paper jam notification means for notifying that the paper jam has occurred is provided. It is possible to prevent the paper jam from getting worse by trying to eject the sheet, and further the device from being damaged by the paper jam. Further, since a paper jam is notified, a recording sheet that cannot be discharged due to a paper jam is removed by the user or maintenance manager of the image forming apparatus.

Further, the recovery control may be control for cleaning toner remaining in the peripheral device due to the second CPU running away during image formation and image stabilization processing. In this way, even if the second CPU runs out of control during image formation, the residual toner can be discharged earlier, so that the normal state can be restored earlier.
In this case, if the toner remaining determining means for determining whether toner remains in the peripheral device and the toner remaining determining means determines that no toner remains, the recovery control is prohibited. It is even better to have a cleaning prohibiting means. In this way, cleaning is not performed unless the toner remains, so that the normal state can be restored more quickly.

  The second CPU is provided with a storage means writable by the second CPU, the second CPU periodically writes to the storage means, and the runaway detection means is predetermined by the second CPU in the storage means. If not written for more than a time, it may be determined that the second CPU is running out of control. In this way, even if the first and second CPUs are mounted on one SOC and the SOC does not have a watchdog timer, the second CPU can run away. Can be detected.

The reset means may reset the second CPU according to a command from the first CPU.
Further, if the operation of the peripheral device is stopped prior to executing the recovery control, the first CPU prevents the second CPU in a runaway state from operating the peripheral device abnormally. Can do.

1 is a diagram illustrating a main configuration of an image forming apparatus according to an exemplary embodiment. 2 is a block diagram illustrating a main configuration of a control system of the image forming apparatus 1. FIG. It is a sequence diagram which shows operation | movement of a control system when the runaway of sub CPU203 is detected, Comprising: (a) shows operation | movement which concerns on a prior art, (b) has shown operation | movement which concerns on this Embodiment. FIG. 5 is a flowchart showing processing for detecting a runaway of the sub CPU 203, where (a) shows processing executed by the main CPU 201, and (b) shows processing executed by the sub CPU 203. FIG. 6 is a flowchart showing the operation of the main CPU 201 when the sub CPU 203 runs away during the image forming operation. 6 is a timing chart illustrating a control operation of a recording sheet conveyance system in recovery control. 6 is a flowchart showing the operation of the main CPU 201 when the sub CPU 203 runs away during the image forming operation. 6 is a timing chart illustrating sheet feeding control during normal operation and runaway in the present embodiment. It is a timing chart which shows the cleaning process of a resist pattern. 7 is a flowchart showing the operation of the main CPU 201 when the sub CPU 203 runs away during image stabilization processing. It is a timing chart which shows the operation | movement in the case of an image stabilization process.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the present embodiment will be described.
FIG. 1 is a diagram illustrating a main configuration of the image forming apparatus according to the present embodiment. The image forming apparatus 1 is a so-called intermediate transfer type color image forming apparatus, and includes image forming units 101Y to 101K as shown in FIG. Each of the image forming units 101Y to 101K has the same configuration, and the outer peripheral surface of the cylindrical photosensitive drum 102 is uniformly charged by the charging device 103 to obtain a predetermined potential, and then the charged region is charged. The exposure device 104 performs image exposure according to the document image, and forms an electrostatic latent image.

  The developing device 105 develops the electrostatic latent image by supplying each color toner of YMCK supplied from the toner cartridges 108Y to 108K onto the outer peripheral surface of the photosensitive drum 102 by the developing roller 105a to which a developing bias is applied. A visible toner image is obtained. A primary transfer bias is applied to the primary transfer rollers 106 </ b> Y to 106 </ b> K, and a visible toner image is primarily transferred from the outer peripheral surface of the photosensitive drum 102 onto the intermediate transfer belt 110 by electrostatically adsorbing toner. To do. After the primary transfer of the visible toner image onto the intermediate transfer belt 110, the toner remaining on the outer peripheral surface of the photosensitive drum 102 is removed by the cleaning device 107.

  The intermediate transfer belt 110 is stretched between a secondary transfer counter roller 111 and a driven roller 112, and rotates in the direction of arrow A by being driven and rotated by a secondary transfer counter roller 111 that is driven to rotate by a main motor described later. While running, the toner images of each color of YMCK are sequentially primary transferred to form a color image. The driven roller 112 is driven to rotate by a frictional force with the intermediate transfer belt 110 that rotates.

  In parallel with the above, in the paper feeding cassette 120 containing the recording sheet S, the recording sheet S is sent out one by one by the pickup roller 121 and passes through the timing roller 115 and the secondary transfer counter roller 111 and the secondary transfer. It is conveyed to the secondary transfer nip formed by the transfer roller 113. A secondary transfer bias is applied to the secondary transfer roller 113, and a toner image (color image) carried on the intermediate transfer belt 110 is electrostatically transferred to the recording sheet S in the secondary transfer nip.

  Note that the rotational driving force is transmitted to the timing roller 115 via a timing clutch (not shown). When the timing clutch is turned on and off, the toner image carried on the intermediate transfer belt 110 is recorded on the recording sheet S. The timing at which the recording sheet S is conveyed is adjusted so that the recording sheet S is transferred to the upper desired position. A pre-timing sensor 114 is disposed on the conveyance path of the recording sheet S from the pickup roller 121 to the timing roller 115 and detects the passage of the recording sheet S.

  The recording sheet S carrying the toner image is detected by the fixing loop sensor 116 and then conveyed to the fixing device 100. The fixing device 100 includes a fixing roller that heats the toner image and a pressure roller that presses against the fixing roller to form a fixing nip, and the recording sheet S is passed through the fixing nip, whereby the toner image Is melted and pressed onto the recording sheet S. Thereafter, the recording sheet S is detected as being discharged from the fixing device 100 by the paper discharge sensor 117, and is discharged onto the paper discharge tray 131 by the paper discharge roller 130. On the other hand, the toner remaining on the intermediate transfer belt 110 after the secondary transfer is conveyed in the direction of arrow A and then removed by the cleaning device 109.

[2] Configuration of Control System Next, the configuration of the control system that controls the operation of the image forming apparatus 1 will be described.
FIG. 2 is a block diagram illustrating a main configuration of the control system of the image forming apparatus 1. As shown in FIG. 2, the image forming apparatus 1 includes an SOC 200, and the CPU 200 includes two CPUs, a main CPU 201 and a sub CPU 203. When the power is turned on, the main CPU 201 and the sub CPU 203 both read a control program (firmware) from a flash ROM (Read Only Memory) 210 via the bus 230 and execute the read control program.

  The main CPU 201 is used for system controller control, controls the operation panel 211 via the bus 230, displays information for the user of the image forming apparatus 1, and receives instruction inputs from the user. Further, the main CPU 201 receives a print job from another apparatus by transmitting / receiving data to / from another apparatus via a network interface (I / F: Interface) 212.

  The SOC 200 includes a shared RAM (Random Access Memory) 202, and both the main CPU 201 and the sub CPU 203 write data to the shared RAM 202 and read data from the shared RAM 202 via the internal bus 204. Can do. The main CPU 201 transmits a print instruction to the sub CPU 203 through the internal bus 204. When the print operation is completed, the sub CPU 203 transmits a print end notification to the main CPU 201. The sub CPU 203 is used for engine control and executes image formation.

Note that both the main CPU 201 and the sub CPU 203 can perform sheet discharge control for discharging the recording sheet on the conveyance path to the outside of the apparatus and cleaning control for cleaning the toner attached to the secondary transfer roller 113.
Further, the SOC 200 includes a register for resetting the main CPU 201 and a register for resetting the sub CPU 203. By writing predetermined values to these registers, the main CPU 201 can reset the sub CPU 203, and the sub CPU 203 can reset the main CPU 201.

  The main CPU 201 and the sub CPU 203 are all connected via the bus 230 to the main motor 213, the sub motor 214, the primary transfer clutch 215, the secondary transfer clutch 216, the timing clutch 217, the paper feed clutch 218, the fixing clutch 219, and the secondary. The peripheral devices such as the transfer bias circuit 220, the primary transfer pressure contact / separation sensor 221, the secondary transfer pressure contact / separation sensor 222, the fixing pressure contact / separation sensor 223, the pre-timing sensor 114, the fixing loop sensor 116, and the paper discharge sensor 117 are monitored and controlled. The main motor 213 rotationally drives the secondary transfer roller 113, the timing roller 115, and the pressure roller provided in the fixing device 100. The sub motor 214 rotates and drives the primary transfer rollers 106Y to 106K.

  The sub CPU 203 refers to the primary transfer pressure contact / separation sensor 221, and the primary transfer rollers 106 </ b> Y to 106 </ b> C that primarily transfer the toner images of YMC colors among the primary transfer rollers 106 </ b> Y to 106 </ b> K are pressed against the intermediate transfer belt 110. Check if it is. Further, the sub CPU 203 controls the primary transfer clutch 215 to press all the primary transfer rollers 106Y to 106K against the intermediate transfer belt 110 during color printing, while one of the primary transfer rollers 106Y to 106K during monochrome printing. The secondary transfer rollers 106Y to 106C are separated from the intermediate transfer belt 110, and only the primary transfer roller 106K is brought into pressure contact with the intermediate transfer belt 110.

  The timing clutch 217 synchronizes the toner image carried on the intermediate transfer belt 110 and the recording sheet by connecting or blocking transmission of the rotational driving force from the main motor 213 to the timing roller 115. . The sheet feeding clutch 218 is a clutch that transmits and disconnects the rotational driving force of the main motor 213 to the pickup roller 121. When the sheet feeding clutch 218 is connected, the pickup roller 121 is rotated and the recording sheet S is fed. The

  The secondary transfer clutch 216 is a clutch that performs pressure contact and separation between the secondary transfer counter roller 111 and the secondary transfer roller 113, and presses these rollers when forming an image or discharging a remaining sheet. The secondary transfer pressure contact / separation sensor 222 detects the pressure contact / separation state between the secondary transfer counter roller 111 and the secondary transfer roller 113. The fixing clutch 219 is a clutch that presses and separates the fixing roller and the pressure roller included in the fixing device 100, and presses the fixing roller and the pressure roller when forming an image or discharging a residual sheet. The fixing pressure contact / separation sensor 223 detects the pressure contact / separation state between the fixing roller and the pressure roller. The secondary transfer bias circuit 220 applies a secondary transfer bias between the secondary transfer counter roller 111 and the secondary transfer roller 113.

The image forming apparatus 1 needs to perform communication processing in the main CPU 201 in order to receive an image forming job from another apparatus via a network. For this reason, the main CPU 201 executes an OS (Operating System, which is Linux (registered trademark) in the present embodiment) that is rich in network-related middleware.
In Linux (registered trademark), depending on the size of the processing load being executed, the waiting time until the interrupt control is executed may take 100 milliseconds or more. For this reason, if engine control is performed using Linux (registered trademark), the sensor value reading timing and the output timing of the control signal to the peripheral device may be lost, so the sub CPU 203 has Linux (registered trademark). ) Is executed without real-time processing.

[3] Operation of Control System Next, the operation of the control system will be described.
(1) Outline First, an outline and effect of the operation of the control system when the runaway of the sub CPU 203 is detected will be described in comparison with the operation of the control system according to the prior art.

  FIG. 3 is a sequence diagram showing the operation of the control system when a runaway of the sub CPU 203 is detected, where (a) shows the operation according to the prior art, and (b) shows the operation according to the present embodiment. Show. As shown in FIG. 3A, in the conventional technique, when the main CPU 201 detects the runaway of the sub CPU 203 after the sub CPU 203 starts running away, the main CPU 201 resets the sub CPU 203. After the reset, the sub CPU 203 downloads firmware (FW: firmware).

  When the sub CPU 203 completes downloading of the firmware, the sub CPU 203 executes recovery control according to the firmware. The content of this recovery control is to cause the peripheral device that performs image formation to perform a recovery operation, and, as will be described later, differs depending on the processing that the image forming apparatus 1 is executing when the sub CPU 203 runs away. When the sub CPU 203 completes the recovery control, the image forming apparatus 1 returns to normal operation.

  On the other hand, in the present embodiment, as shown in FIG. 3B, unlike the prior art, when the main CPU 201 resets the sub CPU 203, the main CPU 201 subsequently executes recovery control. In this way, since the recovery control can be completed early by starting the recovery control early, the downtime of the image forming apparatus 1 can be shortened and the normal operation can be returned to the normal operation earlier than the above-described conventional technique. be able to.

(2) Detection of Runaway Next, processing in which the main CPU 201 detects runaway of the sub CPU 203 will be described.
As a method for detecting the runaway of the CPU, a detection method using a watchdog timer is well known. When the SOC 200 includes a watchdog timer, it is effective to use the watchdog timer. As a known technique for detecting the runaway of the sub CPU 203 using a watch dog timer, for example, there is a technique described in Japanese Patent Application Laid-Open No. 2000-326591.

  On the other hand, when the SOC 200 does not have a built-in watchdog timer, it is necessary to externally attach the watchdog timer to the SOC 200, which is contrary to the advantage of the SOC that can reduce the scale of the apparatus and reduce circuit mounting effort. become. In this case, for example, the runaway of the sub CPU 203 can be detected using the shared RAM 202 built in the SOC 200 as follows.

  FIG. 4 is a flowchart showing a process for detecting a runaway of the sub CPU 203, where (a) shows a process executed by the main CPU 201, and (b) shows a process executed by the sub CPU 203. As shown in FIG. 4B, after the reset, the sub CPU 203 sets a timer (S410) and starts up (S411). When the time set in the timer (for example, 10 milliseconds) elapses and a timeout occurs (S412: YES), the detection flag is cleared (S413), and the process proceeds to step S411 to repeat the above processing.

  The detection flag is a storage area on the shared RAM 202, and 1 is written at the time of setting and 0 is written at the time of clearing. In the present embodiment, the main CPU 201 is set and the sub CPU 203 is cleared. The timer holds the set setting time, and times out after the set time elapses every time it is started unless the setting time is changed.

  As shown in FIG. 4A, the main CPU 201 first clears the runaway flag after reset (S401). Similar to the detection flag, the runaway flag is a storage area on the shared RAM 202, and 1 is written when set, and 0 is written when cleared. In the present embodiment, the main CPU 201 performs both setting and clearing, and the sub CPU 203 only refers to the value of the runaway flag and does not perform any operation.

  Next, the main CPU 201 sets a detection flag (S402), sets a timer (S403), and starts the timer (S404). Thereafter, when a timeout occurs (S405: YES), the detection flag on the shared RAM 202 is referred to. If the detection flag is cleared by the sub CPU 203 (S406: YES), it is determined that the sub CPU 203 is not running away. The detection flag is set (S407), and the process proceeds to step S404. If the detection flag is not cleared (S406: NO), it is determined that the sub CPU 203 has runaway and the detection flag has not been cleared, so the runaway flag is set (S408).

Note that the set time that the main CPU 201 sets in the timer should be longer than the set time that the sub CPU 203 sets in the timer. This is to prevent erroneous detection of the runaway of the sub CPU 203 by causing the sub CPU 203 to clear the detection flag with certainty.
(3) Operation of main CPU 201 Next, regarding the operation of the main CPU 201 when the runaway of the sub CPU 203 is detected, when the sub CPU 203 runs away during the image forming operation, and when the sub CPU 203 runs away during the image stabilization process. This will be explained separately.

(A) Runaway during image forming operation If the sub CPU 203 runs away during an image forming operation, there is a possibility that a recording sheet in the middle of image formation remains in the apparatus. For this reason, before the image forming apparatus 1 is returned to normal, it is necessary to discharge the remaining sheet as recovery control. Conventionally, the residual sheet discharge processing is performed by the sub CPU 203 that has returned to normal by reset. This is because the control for conveying the recording sheet requires real-time property, and the sub CPU 203 controls the recording sheet conveyance system.

  FIG. 5 is a timing chart showing the control operation of the recording sheet conveyance system in the normal state. As shown in FIG. 5, after the main motor 213 is started, an image synchronization signal (TOD: Top of Data) Hi pulse is used as an opportunity to synchronize the toner image conveyance position and the recording sheet conveyance position. A timing clutch 217 is connected, and the recording sheet is conveyed to the secondary transfer position.

  In this case, the sub CPU 203 can connect the timing clutch 217 in real time without delay, but the main CPU 201 executes interrupt control for the convenience of mounting the Linux (registered trademark) which is a non-real time OS. In some cases, a delay of 100 milliseconds or more may occur due to overhead such as task switching. When the system speed (recording sheet conveyance speed) of the image forming apparatus 1 is 185 mm / second (30 sheets / minute), a deviation of 18.5 mm occurs at the transfer position of the toner image due to a delay of 100 milliseconds. Accordingly, it is desirable to control the recording sheet conveyance system using the sub CPU 203 during image formation.

  On the other hand, in the recovery control, since the toner image is not transferred and only the recording sheet is discharged, real-time performance is not required. FIG. 6 is a timing chart showing the control operation of the recording sheet conveyance system in the recovery control. As shown in FIG. 6, in the recovery control, after the main motor 213 is started and the rotation of the main motor 213 is stabilized, the timing clutch 217 is connected. As a result, the recording sheet remaining at the position of the pre-timing sensor 114 is conveyed, passes through the position of the pre-timing sensor 114, the sheet leading edge is detected by the paper ejection sensor 117, and the sheet trailing edge passes the paper ejection sensor 117. After passing, the recording sheet is discharged out of the machine. In this case, as long as the main motor 213 rotates stably, the timing at which the timing clutch 217 is connected may be anytime, and real-time performance is not required.

Therefore, in the present embodiment, the main CPU 201 executes the recovery control as follows.
FIG. 7 is a flowchart showing the operation of the main CPU 201 when the sub CPU 203 runs away during the image forming operation. As shown in FIG. 7, when the main CPU 201 detects a runaway of the sub CPU 203, first, the main CPU 201 resets the sub CPU 203 (S701). When the sub CPU 203 is reset, it reads the control program from the flash ROM 210 and resumes operation.

  Subsequently, the main CPU 201 stops the peripheral device (S702). The sub CPU 203 is in a state where it cannot correctly control peripheral devices (such as a motor) until it returns to normal operation after reset. Therefore, in order to prevent the peripheral device from operating abnormally due to unauthorized control of the sub CPU 203, the main CPU 201 needs to stop the peripheral device.

  Next, it is confirmed whether or not the recording sheet remains in the apparatus. In the present embodiment, the secondary transfer roller 113 is pressed against the secondary transfer counter roller 111 by the secondary transfer clutch 216 during conveyance of the recording sheet. By detecting the presence or absence of this pressure contact using the secondary transfer pressure contact / separation sensor 222, it is confirmed whether or not the recording sheet remains in the apparatus.

If the recording sheet does not remain in the apparatus (S703: NO), the process ends. If the recording sheet remains in the apparatus (S703: YES), it is confirmed whether it can be discharged out of the apparatus.
FIG. 8 is a timing chart showing the sheet feeding control in the present embodiment at the normal time and at the time of runaway. As shown in FIG. 8, at the normal time, first, the sub CPU 203 activates the main motor 213 and connects the paper feed clutch 218. Accordingly, when the pre-timing sensor 114 detects the recording sheet carried out from the paper feed cassette 120, the sub CPU 203 disconnects the paper feed clutch 218. Thereafter, when it is time to convey the recording sheet, the sub CPU 203 connects the timing clutch 217 and rotationally drives the timing roller 115 to secondarily transfer the toner image onto the recording sheet. Note that, when images of a plurality of pages are continuously formed, the paper feed clutch 218 is continuously connected, and the next recording sheet is carried out from the paper feed cassette 120.

  On the other hand, if the sub CPU 203 runs out of control before the timing clutch 217 is connected after the next recording sheet starts to be carried out from the paper feed cassette 120, a paper jam (jam) occurs as follows. That is, when the timing clutch 217 is not connected, the timing roller 115 is not driven to rotate, so that the recording sheet waiting for the secondary transfer cannot be passed through the timing roller 115 and is continuously conveyed to the pickup roller 121. The paper is jammed by being bent into a bellows before the timing roller 115. Further, the next recording sheet also causes a paper jam. In such a case, the recording sheet cannot be automatically discharged. Therefore, by referring to the connection state of the timing clutch 217, it can be determined whether or not the recording sheet can be automatically discharged.

  When the remaining sheet can be discharged outside the apparatus (S704: YES), the main CPU 201 discharges the recording sheet outside the apparatus by rotationally driving the main motor 213 and the sub motor 214 as recovery control. (S705), the process ends. When discharging the recording sheet outside the apparatus, first, the main motor 213 is started, and then the secondary transfer clutch 216 is connected to bring the secondary transfer counter roller 111 and the secondary transfer roller 113 into pressure contact with each other. At the same time, the fixing clutch 219 is connected and the fixing roller included in the fixing device 100 is brought into pressure contact.

Further, the timing clutch 217 is connected and the timing roller 115 is driven to rotate, whereby the recording sheet is discharged out of the apparatus. Thereafter, the secondary transfer clutch 216, the fixing clutch 219, and the timing clutch 217 are disconnected, and then the main motor 213 is stopped.
On the other hand, if the remaining sheet cannot be discharged outside the apparatus (S704: NO), the user of the image forming apparatus 1 is notified of the paper jam using the operation panel 211 (S706), and the process is terminated.

Thus, if recovery control is performed by the main CPU 201 without waiting for the reset of the sub CPU 203 to be completed, the image forming apparatus 1 can be returned to normal earlier.
(B) Runaway during image stabilization processing Next, processing when the sub CPU 203 runs away during image stabilization processing will be described.
In the image stabilization process, a resist pattern (toner patch) is formed on the intermediate transfer belt 110 and the density and positional deviation thereof are measured in order to optimize the transfer potential and transfer position of the toner image. Therefore, if the image stabilization process cannot be completed normally because the sub CPU 203 runs away during the image stabilization process, a resist pattern may remain on the outer peripheral surface of the secondary transfer roller 113. There is sex. Therefore, when the sub CPU 203 runs away during the image stabilization process, it is necessary to clean the resist pattern remaining on the outer peripheral surface of the secondary transfer roller 113. Conventionally, the sub CPU 203 that has returned to normal by reset controls the cleaning process of the secondary transfer roller 113.

  FIG. 9 is a timing chart showing a resist pattern cleaning process. As shown in FIG. 9, after the main motor 213 is started and the secondary transfer clutch is connected, the secondary transfer bias circuit 220 is controlled while the secondary transfer roller 113 is rotated one or more rounds. −500 V is applied as the next transfer bias. Next, +500 V is applied as a secondary transfer bias this time while the secondary transfer roller 110 is rotated more than once. This operation is executed a total of three times, and after the toner is blown onto the intermediate transfer belt 110, the main motor 213 is stopped.

Thereafter, the secondary transfer clutch is disconnected and the main motor 213 is stopped. The toner on the intermediate transfer belt 110 is removed by the cleaning device 109. As described above, since the real-time property is not required for the cleaning process of the resist pattern, the main CPU 201 executes the cleaning process of the resist pattern as follows in the present embodiment.
FIG. 10 is a flowchart showing the operation of the main CPU 201 when the sub CPU 203 runs away during the image stabilization process. As shown in FIG. 10, when the main CPU 201 detects the runaway of the sub CPU 203, the main CPU 201 resets the sub CPU 203 (S1001) and stops the peripheral devices (S1002). When the sub CPU 203 is reset, it reads the control program from the flash ROM 210 and resumes operation.

  Thereafter, if it is during the image stabilization process that the sub CPU 203 has run away (S1003: YES), it is confirmed whether or not a resist pattern has been formed on the intermediate transfer belt 110. FIG. 11 is a timing chart showing the operation during the image stabilization process. As shown in FIG. 11, in the image stabilization process, first, the main motor 213 is started, the image synchronization signal becomes a Hi pulse, and a resist pattern is formed. Thereafter, when the sampling of the density and position of the formed resist pattern is completed, the rotation of the main motor 213 is stopped. Therefore, if the Hi pulse of the image synchronization signal is monitored, it can be determined whether or not a resist pattern has been formed based on the presence or absence thereof.

  If it is determined from the image synchronization signal that a resist pattern has been formed (S1004: YES), the intermediate transfer belt 110 is cleaned (S1005). After the cleaning of the intermediate transfer belt 110 is completed, if the sub CPU 203 runs away from the image stabilization process (S1003: NO) and the resist pattern is not formed (S1004: NO), the process is performed. finish.

In this way, if the intermediate transfer belt 110 is cleaned by the main CPU 201 without waiting for the completion of the reset of the sub CPU 203, the image forming apparatus 1 can be returned to normal earlier.
[4] Modifications Although the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .

  (1) In the above-described embodiment, the case where the main CPU 201 and the sub CPU 203 configure the SOC has been described, but the present invention is not limited to this, and the main CPU 201 and the sub CPU 203 configure a dual core processor. It may be a separate processor. In any case, the effects of the present invention can be obtained.

  (2) In the above embodiment, the case where the main CPU 201 monitors whether or not the sub CPU 203 is running out of control has been described. In addition, the sub CPU 203 monitors whether or not the main CPU 201 is running out of control. You may let them. The reliability of the image forming apparatus 1 can be further improved by causing the main CPU 201 and the sub CPU 203 to monitor each other and resetting the runaway CPU when the runaway is detected. Note that the method of monitoring the runaway of the main CPU 201 by the sub CPU 203 may be the same as the method of monitoring the runaway of the sub 203 by the main CPU 201 as described in the above embodiment. Further, for example, a monitoring method disclosed in JP 2000-326591 A may be applied.

(3) In the above-described embodiment, the case where the recovery control (residual sheet discharge control and residual toner cleaning control) is completed before the sub CPU 203 shifts to normal operation after resetting has been described. Needless to say, the recovery control may be completed after the sub CPU 203 shifts to a normal operation after resetting.
However, when executing the discharge control of the remaining sheet, the sub CPU 203 that has shifted to the normal operation detects the jam of the remaining sheet in the same manner as in the normal state, and prevents the discharge control from being interrupted. It is desirable to suppress jam detection by the sub CPU 203 until the control is completed.

  For this reason, for example, a recovery control flag indicating whether recovery control is being performed is prepared in the shared RAM 202, and the main CPU 201 may update the recovery control flag. Then, the sub CPU 203 may refer to the recovery control flag when a jam is detected, and continue discharging the remaining sheet if the recovery control is being performed, and stop the conveyance of the jammed paper if the recovery control is not being performed.

In this way, even when the recovery control is completed after the sub CPU 203 has shifted to normal operation after resetting, the remaining sheets can be discharged without being interrupted by the sub CPU 203 that has shifted to normal operation. .
(4) In the above embodiment, the case where the main CPU 201 performs the cleaning process of the remaining resist pattern (toner) when the sub CPU 203 runs away during the image stabilization process has been described. Needless to say, the main CPU 201 may similarly perform the cleaning process of the residual toner when the sub CPU 203 runs away during the image formation instead of the image stabilization process. Also in this case, the time required for the sub CPU 203 to recover from the runaway can be shortened as in the above embodiment.

(5) In the above embodiment, the case where the main CPU 201 detects the runaway of the sub CPU 203 and resets the sub CPU 203 has been described. However, it goes without saying that the present invention is not limited to this, and means other than the main CPU 201 Thus, the sub CPU 203 may be detected by detecting the runaway of the sub CPU 203 and reset.
For example, if the timer in which the predetermined time T1 is set in advance is restarted at the time interval T2 shorter than the predetermined time T1 by the sub CPU 203 and the sub CPU 203 does not restart the timer, the timer interrupt is applied to the reset line of the sub CPU 203. May be input. In this way, it is possible to eliminate the load for the main CPU 201 to monitor the runaway of the sub CPU 203. In this case, an interrupt signal of the timer may be input to the main CPU 201, and the main CPU 201 may be caused to execute recovery control in response to the interrupt signal.

  (6) In the above embodiment, the case where the image forming apparatus 1 is an intermediate transfer type color image forming apparatus has been described, but it is needless to say that the present invention is not limited to this. It may be an adopted image forming apparatus or a monochrome image forming apparatus. In addition, it may be a copying machine equipped with an image reading device, or may be a facsimile machine equipped with a communication function, or a multi-function machine (MFP: Multi Function Peripheral) that combines these functions. There may be. In any case, the effect can be obtained by applying the present invention.

  The image forming apparatus according to the present invention is useful as a technique for shortening the recovery time from a system failure caused by CPU runaway.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 109 ... Cleaning apparatus 110 ... Intermediate transfer belt 111 ... Secondary transfer counter roller 113 ... Secondary transfer roller 114 ... Pre-timing sensor 115 ... Timing roller 116 ... Fixing loop sensor 117 ... Discharge sensor 120 ... Paper feed cassette 121 ... Pickup roller 130 ... Paper discharge roller 200 ... SOC
201: Main CPU
202 ... Shared RAM
203 ... Sub CPU
210 ... Flash ROM
213 ... Main motor 214 ... Sub motor 215 ... Primary transfer clutch 217 ... Timing clutch 220 ... Secondary transfer bias circuit

Claims (9)

A peripheral device having a conveying means for conveying the recording sheet and a transfer means for transferring the toner image to the recording sheet;
A first CPU for controlling the peripheral device by non-real time control;
A second CPU for controlling the peripheral device by real-time control;
A runaway detection means for detecting runaway of the second CPU,
The first CPU is
While the second CPU is controlling the peripheral device, if the runaway detection means detects the runaway of the second CPU, the second CPU is reset,
Prior to completion of resetting of the second CPU, recovery control for returning the peripheral device to a normal state is started. 2. The recovery control according to claim 1, wherein the recovery control is a control for discharging the recording sheet remaining on the transport path of the transport unit to the outside of the apparatus when the second CPU runs away during image formation. Image forming apparatus. The second CPU includes a conveyance stop unit that detects a paper jam on the conveyance path and stops conveyance of the recording sheet by the conveyance unit.
The image forming apparatus according to claim 2, wherein the first CPU starts the recovery control after prohibiting the conveyance stop by the conveyance stop unit. A discharge enable / disable determining unit that determines whether or not the recording sheet remaining on the transport path can be discharged out of the apparatus;
A paper jam notifying unit for prohibiting the recovery control and notifying that a paper jam has occurred when the discharge possibility determining unit determines that the recording sheet cannot be discharged. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. 2. The control according to claim 1, wherein the recovery control is control for cleaning toner remaining in the peripheral device due to a runaway of the second CPU during image formation and image stabilization processing. Image forming apparatus. A toner residue determining means for determining whether toner remains in the peripheral device;
The image forming apparatus according to claim 5, further comprising: a cleaning prohibiting unit that prohibits the recovery control when the toner remaining determining unit determines that no toner remains. Storage means writable from the second CPU;
The second CPU periodically writes to the storage means;
2. The image formation according to claim 1, wherein the runaway detection unit determines that the second CPU is running away if the second CPU does not write in the storage unit for a predetermined time or more. apparatus. The image forming apparatus according to claim 1, wherein the reset unit resets the second CPU according to a command from the first CPU. The image forming apparatus according to claim 1, wherein the first CPU stops the operation of the peripheral device prior to executing the recovery control.

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