JP2010152087A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents missing of pages due to the occurrence of trouble. <P>SOLUTION: When jamming is detected (S703: YES), rotation of rollers other than an ejection roller 205 is stopped (S709). If a recording sheet on which an image has been formed is not being ejected (S710: NO), a recording sheet on which the image has been fixed does not remain inside the apparatus, so that the rotation of the ejection roller 205 is stopped (S711). If the recording sheet on which the image has been formed is being ejected (S710: YES), the rotation of the ejection roller 205 is stopped (S711) after waiting for a time-out state (S704: YES) and ejecting the recording sheet on which the image has been fixed to the outside of the apparatus. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to a technique for preventing page missing caused by a trouble such as a jam.

In recent years, image forming apparatuses such as copying machines, printers, facsimiles, etc. once stop the image forming operation when the occurrence of a jam is detected, and subsequently perform image formation when the jammed recording sheet is removed.
However, when a jam occurs on a recording sheet before transfer when a large number of pages are continuously imaged, if an image formation is immediately stopped and a jam error is notified, the preceding undischarged recording sheet is again displayed. Therefore, an image must be formed, and a recording sheet and other waste are generated.

In response to such a problem, a technique has been proposed in which, when a jam occurs on a recording sheet before transfer, image formation is stopped after the completion of the fixing process of the preceding recording sheet, and a jam error is notified. (See Patent Document 1). In this way, the fixing process for the preceding recording sheet can be completed, so that waste when a jam occurs can be reduced.
Japanese Patent Laid-Open No. 10-31336

  Incidentally, after the jammed recording sheet is removed, the image forming apparatus manages to which page of the print job composed of a plurality of pages image formation has been completed in order to perform subsequent image formation. For example, it is determined whether or not the image formation is completed by arranging a sensor on a conveyance path from the fixing device to the outside of the apparatus until the recording sheet is discharged and monitoring whether or not the recording sheet passes for each page. The

On the other hand, according to the above-described prior art, when a plurality of sheets are continuously formed, image formation is stopped immediately when a jam occurs on the recording sheet after transfer. In this case, if it is determined that any page has completed the fixing process and the image formation has been completed, and the image formation is stopped before being discharged out of the apparatus, the page remains in the apparatus. End up.
For this reason, when the user discards all of the recording sheets left in the apparatus when the jam is eliminated, the page is not formed even if image formation is subsequently performed, resulting in missing pages.

Such a problem is not limited to the image forming apparatus according to the above-described prior art, and an image forming apparatus that manages whether or not image formation is completed for each page and forms an image only on pages in which image formation is not completed after jamming is resolved. Generally applicable. The same applies when image formation is stopped due to a trouble other than a jam.
The present invention has been made in view of the above-described problems, and an object thereof is to provide an image forming apparatus that prevents page missing caused by occurrence of a trouble.

  In order to achieve the above object, the image forming apparatus according to the present invention interrupts an image forming job when a trouble occurs during execution of the image forming job, and after the trouble is solved, the image forming apparatus starts an image from a page that has not completed image forming. An image forming apparatus that resumes formation, a fixing unit that fixes a toner image on a recording sheet, a discharge unit that discharges the recording sheet on which the toner image is fixed, and a fixing unit on a conveyance path of the recording sheet. If the rear end of the recording sheet passes through the paper discharge sensor that detects the presence or absence of the recording sheet at that position, and is disposed upstream of the discharge means, the recording sheet has completed image formation. A determination unit that determines that the image forming job is interrupted, an estimation unit that estimates whether the recording sheet is passing through the discharge unit, If it is estimated that a recording sheet for which image formation has not been completed is passing through the discharge means, the discharge means is immediately stopped; otherwise, the recording sheet has passed through the discharge means. And a discharge control means for stopping the discharge means later.

In this way, by continuing to operate the discharge means even after a trouble has occurred, the recording sheet that has been fixed is surely discharged to the outside of the machine. Omission can be prevented.
In this case, if it is estimated that a recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected, the discharge control means, after a time sufficient to discharge the recording sheet has elapsed. The discharging means may be stopped. Further, when it is estimated that the recording sheet on which image formation has been completed is passing through the discharging means when a trouble is detected, the discharging control means is estimated that the recording sheet is not passing through the discharging means. Later, the discharging means may be stopped.

  An image forming apparatus that interrupts an image forming job when a problem occurs during the execution of the image forming job and restarts image formation from a page that has not completed the image formation after the trouble is resolved. A fixing unit that fixes the toner image; a discharge unit that is driven by a drive motor that is common to the fixing unit and discharges the recording sheet on which the toner image has been fixed; In addition, a paper discharge sensor that is arranged upstream of the discharge means and detects the presence or absence of a recording sheet at the position, and that the recording sheet has completed image formation when the trailing edge of the recording sheet passes the paper discharge sensor. A determination unit for determining, a detection unit for detecting a trouble that includes a fixing unit jam that is a paper jam in the fixing unit and that should interrupt an image forming job, and a recording sheet An estimation means for estimating whether or not the toner is passing through the discharging means, and when a fixing portion jam is detected, and when a trouble other than the fixing portion jam is detected and image formation is not completed. When it is estimated that the sheet is passing through the discharge unit, the drive motor is immediately stopped, a trouble other than the fixing portion jam is detected, and the recording sheet on which image formation is completed is passing through the discharge unit. If the recording sheet is estimated to be, the motor control means for stopping the drive motor after the recording sheet has passed through the discharge means.

In this way, since the fixing unit and the discharging unit are driven by a common drive motor, it is possible to reduce the number of parts of the image forming apparatus and to reduce the price, and to reduce the fixing unit jam. Can be prevented.
An image forming apparatus that interrupts an image forming job when a problem occurs during the execution of the image forming job and restarts image formation from a page that has not completed the image formation after the trouble is resolved. A fixing unit that fixes the toner image; a discharge unit that is driven by a drive motor that is common to the fixing unit and discharges the recording sheet on which the toner image has been fixed; In addition, a paper discharge sensor that is arranged upstream of the discharge means and detects the presence or absence of a recording sheet at the position, and that the recording sheet has completed image formation when the trailing edge of the recording sheet passes the paper discharge sensor. A determination unit for determining, a detection unit for detecting a trouble that includes a fixing unit jam that is a paper jam in the fixing unit and that should interrupt an image forming job, and a conveyance path The specifying means for specifying the rear end position of the recording sheet for each recording sheet, the estimating means for estimating whether or not the recording sheet is passing through the discharging means, and image formation when trouble is detected. If it is estimated that a recording sheet that has not been completed is passing through the discharge means, the drive motor is immediately stopped, and it is estimated that a recording sheet that has completed image formation is passing through the discharge means and the detected trouble. If the trouble is other than the fixing section jam, the drive motor is stopped after the recording sheet has passed through the discharge means, and it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means and is detected. In the case where the trouble occurred is the fixing unit jam, the distance d1 from the trailing edge of the recording sheet detected immediately before by the paper discharge sensor to the paper discharge unit, the recording sheet jammed in the fixing unit, Relationship between the length d3 in the conveying direction of the recording sheet required for pulling out the recording sheet jammed in the distance d2 and the fixing means from the end to the fixing means,
d2-d3> d1
Then, after the recording sheet has passed through the discharge means, the drive motor is stopped,
d2-d3 <d1
Then, a motor control means for immediately stopping the drive motor is provided.

In this way, even when a fixing portion jam occurs, the fixing portion jam can be kept to such an extent that the recording sheet can be pulled out from the fixing means, and page missing can be prevented.
Even in this case, if it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected, the motor control means has sufficient time to discharge the recording sheet. After the lapse of time, the drive motor means may be stopped, or the motor control means may perform the recording if it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected. The drive motor means may be stopped after it is estimated that the sheet is no longer passing the discharge means.

[1] First Embodiment Hereinafter, a first embodiment of an image forming apparatus according to the present invention will be described 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 an external perspective view showing the main configuration of the image forming apparatus according to the present embodiment.

As shown in FIG. 1, the image forming apparatus 1 includes an image reading unit 101, an image forming unit 102, a paper feeding unit 103, and an operation panel 104.
The image reading unit 101 includes an automatic document feeder (ADF) 111, and upon receiving a user instruction on the operation panel 104, a plurality of sheets placed on the automatic document feeder 111 are placed. The original is sequentially read to generate image data for each page. Image data generated by the image reading unit 101 is processed by an image processing unit (not shown) and used for image formation.

The image forming unit 102 forms a toner image based on image data processed by the image processing unit or image data received from another apparatus, and transfers the toner image onto a recording sheet supplied by the paper feeding unit 103. After fixing, the paper is discharged onto the paper discharge tray 112.
The image reading unit 101 detects a paper jam in the automatic document feeder 111. The image forming unit 102 and the paper feeding unit 103 detect a paper jam of the recording sheet during image formation. When these paper jams are detected during image formation, or when other troubles such as running out of toner are detected, the image reading unit 101 and the paper feeding unit 102 immediately stop the conveyance of the recording sheet, and the paper jams are detected. Notify the user of the occurrence.

The image forming apparatus 1 is provided with doors such as the front door 110, and the user can solve the trouble by opening these doors and taking out a jammed document or recording sheet. Each door is provided with a sensor for detecting an open / closed state. When it is detected that the user has closed the door after the trouble is solved, image formation is subsequently performed.
(2) Internal Structure of Image Forming Apparatus 1 Next, the internal structure of the image forming apparatus 1 will be described with particular attention to the conveyance path for conveying the recording sheet.

FIG. 2 is a cross-sectional view schematically showing the conveyance path of the image forming apparatus 1. As shown in FIG. 2, a paper feed roller 201, a registration roller 202, a photosensitive drum 203, a fixing roller 204, and a discharge roller 205 are arranged on the transport path 200 in order from upstream to downstream.
The paper feed roller 201 is driven to rotate by a paper feed motor 211 and feeds recording sheets stored in the paper feed unit 103 to the transport path 200 one by one.

The registration roller 202 is rotationally driven by a registration motor 212 and adjusts the conveyance timing of the recording sheet so that the toner image is transferred to an appropriate position on the recording sheet.
In this case, a registration sensor 221 is used to detect the positions of the leading edge and the trailing edge of the recording sheet. The registration sensor 221 is disposed on the conveyance path 200 and upstream of the registration roller 202. The registration sensor 221 is also used to detect a jam of the recording sheet before transfer.

The photosensitive drum 203 is rotationally driven by a photosensitive motor 213. The outer peripheral surface of the photosensitive drum 203 is uniformly charged by an imaging unit (not shown), and then an electrostatic latent image is formed by exposure. The electrostatic latent image is developed with toner, whereby a toner image is formed on the outer peripheral surface of the photosensitive drum 203.
The toner image formed on the outer peripheral surface of the photosensitive drum 203 is electrostatically transferred onto the recording sheet by the transfer roller 231. The transfer roller 231 is driven to rotate by the photosensitive drum 203.

The fixing roller 204 is rotationally driven by a fixing motor 214, heats and melts the toner image, and presses the toner image on the recording sheet.
The fixing paper discharge sensor 222 is disposed on the conveyance path 200 downstream of the fixing roller 204, and detects the positions of the leading edge and the trailing edge of each recording sheet. Thus, it is determined whether or not image formation is completed for each recording sheet. The fixing paper discharge sensor is also used for detecting a fixing roller winding jam in which a recording sheet is wound around the fixing roller 204.

The discharge roller 205 is driven to rotate by a discharge motor 215 and discharges the recording sheet onto the discharge tray 112. Note that the registration sensor 221 and the fixing paper discharge sensor 222 are turned on while the recording sheet passes over the sensors, and are turned off otherwise.
(3) Control Configuration of Image Forming Apparatus 1 Next, a configuration for controlling the operation of each unit by the image forming apparatus 1 will be described.

FIG. 3 is a block diagram showing a control configuration of the image forming apparatus 1.
The image forming apparatus 1 includes an engine controller 301 that controls the image forming operation and an MFP (multi functional peripheral) controller 302 that controls the entire operation of the image forming apparatus 1.
The engine controller 301 communicates with the MFP controller 302 via an internal bus. The engine controller 301 acquires sensor information from the registration sensor 221 and the fixing paper discharge sensor 222, and supplies a sheet feeding motor drive circuit 311, a registration motor drive circuit 312, a photosensitive motor drive circuit 313, a fixing motor drive circuit 314, and a discharge motor. The drive circuit 315 is controlled.

A paper feed motor drive circuit 311, a registration motor drive circuit 312, a photoconductor motor drive circuit 313, a fixing motor drive circuit 314, and a discharge motor drive circuit 315 are a paper feed motor 211, a registration motor 212, a photoconductor motor 213, and a fixing motor 214, respectively. And the operation of the discharge motor 215.
As will be described later, the engine controller 301 sets a timer when the rotation of the sheet feeding motor 211 is started to convey a recording sheet, and the registration sensor 221 transits from an off state to an on state within a predetermined time. Whether or not, that is, whether or not the leading edge of the recording sheet reaches the registration sensor 221 detects the register jam.

Similarly, a fixing portion jam is detected depending on whether or not the fixing paper discharge sensor 222 detects the leading edge of the recording sheet within a predetermined time after the registration motor 212 starts to rotate.
The MFP controller 302 controls the image reading unit 101, the operation panel 104, and the image processing unit 303 to accept presentation of information and user input to the user, read a document, and process image data (edge enhancement, color correction, etc.) I do.

(4) Operation at the time of image formation Next, the cooperative operation between the engine controller 301 and the MFP controller 302 at the time of executing image formation will be described separately in two cases of normal operation and jam occurrence.
(A) Normal time First, the normal operation will be described.

  FIG. 4 is a diagram illustrating a communication sequence between the engine controller 301 and the MFP controller 302 in a normal state. As shown in FIG. 4, after the image forming apparatus 1 is turned on, when it is confirmed that the engine controller 301 is ready to form an image, the engine controller 301 is in a state (hereinafter referred to as “engine state”). READY is notified to the MFP controller 302.

After that, for example, when the MFP controller 302 receives a copy instruction (input of an image forming job) from the user on the operation panel 104, the image reading unit 101 reads the document to generate image data, and the image processing unit 303 The image data is processed appropriately.
Next, the MFP controller 302 first transmits a “print request (page 1)” requesting image formation of the first page to the engine controller 301 in order to execute image formation related to the image data page by page. To do.

Upon receiving the “print request (page 1)”, the engine controller 301 rotates the paper feed motor 211 via the paper feed motor drive circuit 311 to pick up one recording sheet, and “paper feed start report”. (Page 1) "is transmitted to the MFP controller 302.
Then, the engine controller 301 appropriately drives the motors 212 to 215 via the drive circuits 312 to 315, and in accordance with the image data and the image forming conditions of the first page related to “print request (page 1)”, the toner image Formation, transfer and fixing.

Thereafter, when the fixing discharge sensor 222 is turned on once and then turned off, it is detected that the trailing edge of the recording sheet related to the image formation on the first page has passed through the fixing discharge sensor 222. Transmits a “discharge completion report (page 1)” to the MFP controller 302.
When the MFP controller 302 receives the “paper feed start report” of the page related to the “print request” transmitted to the engine controller 301 and receives the “discharge completion report”, the MFP controller 302 determines that the image formation on the page has been completed.

When the MFP controller 302 receives the “paper feed start report” for the first page from the engine controller 301, the MFP controller 302 sends the “print request” for the second page to the engine without waiting for the reception of the “discharge completion report” for the page. Transmit to the controller 301. The same applies to the third and subsequent pages.
For the second and subsequent pages, it is determined that the image formation on the page has been completed by receiving both the “paper feed start report” and the “discharge completion report”.

(A) When Jam Occurred Next, regarding the operation at the time of jam occurrence, after the “ejection completion report (page 1)” of FIG. 4 is normally transmitted, the registration sensor detects the jam of the registration portion where the leading edge of the recording sheet is not detected. Let's take an example.
As shown in FIG. 5, when the engine controller 301 transmits a “discharge completion report (page 1)” to the MFP controller 302 and then detects a registration portion jam, the motors 211 to 215 via the drive circuits 311 to 315 are detected. Stop everything.

At the same time, the engine controller 301 transmits a “jam notification (registration unit)” to the MFP controller 302. The engine controller 301 also transmits NOT_READY to the MFP controller 302 as the engine state.
Upon receiving these notifications, the MFP controller 302 notifies the occurrence of a paper jam and causes the operation panel 104 to display a message prompting the removal of jammed paper.

After opening / closing of the jam processing door (not shown) is detected, when both the registration sensor 221 and the fixing paper discharge sensor 222 are turned off, the engine controller 301 transmits READY to the MFP controller 302 as an engine state.
Note that whether or not the recording sheet remains in the apparatus, that is, whether or not the jam has been resolved, is determined based on whether or not both the registration sensor 221 and the fixing paper discharge sensor 222 are turned off.

When READY is received as the engine state, the MFP controller 302 determines a page on which image formation is resumed. That is, since the “discharge completion report” has been received for the first page, it is determined that the image formation has been completed, but since the “discharge completion report” has not been received for the second page, the image formation has been completed. It is judged that it is not.
Therefore, the MFP controller 302 transmits a “print request” for the second page to the engine controller 301. In response to this, the engine controller 301 transmits a “paper feed start report” to the MFP controller 301. After that, when the trailing edge of the recording sheet of the second page passes through the fixing paper discharge sensor 222, the “discharge complete” “Report” is transmitted to the MFP controller 302.

(5) Operation of MFP Controller 302 Next, the operation of the MFP controller 302 when executing the communication sequence as described above will be described in more detail.
FIG. 6 is a flowchart showing main operations of the MFP controller 302. As shown in FIG. 6, when the MFP controller 302 is powered on, the following processing is repeated. That is, when an image forming job is received from the user on the operation panel 104 (S601: YES), the image forming job is recorded (S607).

When the MFP controller 302 receives a jam notification from the engine controller 301 (S602: YES), the MFP controller 302 notifies the user of the occurrence of a jam on the operation panel 104 (S608) and prompts the user to eliminate it.
Upon receiving the discharge completion report from the engine controller 301 (S603: YES), the MFP controller 302 records the page number related to the discharge completion report (S609).

When the MFP controller 302 receives NOT_READY regarding the engine state from the engine controller 301 (S604: YES), it records this (S610).
When the MFP controller 302 receives READY as the engine state from the engine controller 301 (S605: YES), the MFP controller 302 instructs the engine controller 301 to print the page with the smallest page number among the pages that have not received the discharge completion report. Is transmitted (S611). Further, the MFP controller 302 records the READY state as the engine state (S612).

When the MFP controller 302 receives the paper feed start report from the engine controller 301 (S606: YES), the MFP controller 302 refers to the recorded engine state, and if it is in the READY state (S613: YES), the page related to the paper feed start report. In order to print the next page, a print instruction is transmitted to the engine controller 301 (S614).
(6) Operation of Engine Controller 301 Next, the operation of the engine controller 301 when executing the communication sequence as described above will be described in further detail.

FIG. 7 is a flowchart showing main operations of the engine controller 301. As shown in FIG. 7, the engine controller 301 first refers to the fixed paper discharge sensor 222 (S701), and when the fixed paper discharge sensor 222 transitions from the off state to the on state (S702: YES), the sensor The on state is recorded as the state (S706).
The time required for the recording sheet to be discharged onto the discharge tray 112 by the discharge roller 205 is set in the timer (S707), and the rotation of the discharge motor 215 is started via the discharge motor drive circuit 315 (S708). ).

  If a jam is detected (S703: YES), the motors other than the discharge motor 215 are stopped, that is, the paper feed motor 211, the registration motor 212, the photoconductor motor 213, and the fixing motor 214 are stopped. Then, rotation of the rollers other than the discharge roller 205, that is, the paper supply roller 201, the registration roller 202, the photosensitive drum 203, and the fixing roller 204 is stopped (S709).

If the recording sheet on which image formation has been completed is not being discharged (S710: NO), the discharge motor 215 is stopped and the rotation of the discharge roller 205 is stopped (S711). If the recording sheet on which image formation has been completed is being discharged (S710: YES), the process proceeds to step S704 in order to determine whether or not the rotation of the discharge roller 205 should be stopped.
As described above, whether or not the image formation is completed is determined for each recording sheet by the fixing paper discharge sensor 222 detecting the positions of the leading edge and the trailing edge of the recording sheet. Whether or not the recording sheet is being discharged is determined by estimating where the leading edge or the trailing edge of each recording sheet is located on the conveyance path. The position of the recording sheet can be estimated from, for example, driving amounts of the motors 211 to 214 and detection values of the sensors 221 to 222 and the like.

That is, the sensor 221 to 222 detects the passing timing of the leading edge and the trailing edge of the recording sheet, and calculates the displacement from the detected position from the rotation amount of each of the motors 211 to 214. The position can be estimated.
If a time-out occurs in the timer set in step S707 (S704: YES), it is determined that the fixed recording sheet has been discharged onto the paper discharge tray 112, so the rotation of the discharge roller 205 is rotated. Is stopped (S711). As a result, even when a jam is detected, the recording sheet on which fixing has been completed is discharged out of the apparatus. Accordingly, it is possible to prevent missing pages due to the recording sheet having been fixed remaining in the apparatus.

  The engine controller 301 also monitors the transition of the fixing paper discharge sensor 222 from the on state to the off state. When this transition is detected (S705: YES), the sensor state is recorded (S712). ). The engine controller 301 records the off state as the initial sensor state when the power is turned on. The transition of the sensor state is performed by comparing the recorded sensor state with the sensor state detected by the fixing paper discharge sensor 222.

[2] Second Embodiment Next, an image forming apparatus according to a second embodiment of the present invention will be described. The image forming apparatus according to the present embodiment has substantially the same configuration as the image forming apparatus according to the first embodiment, but is different in that the fixing roller and the discharge roller are rotationally driven by a common motor. To do. Hereinafter, the description will be given focusing on the differences.

(1) Internal Structure of Image Forming Apparatus First, the internal structure of the image forming apparatus will be described with particular attention to the transport path for transporting the recording sheet.
FIG. 8 is a cross-sectional view schematically showing the conveyance path of the image forming apparatus. As shown in FIG. 8, a feed roller 801, a registration roller 802, a photosensitive drum 803, a fixing roller 804, and a discharge roller 805 are arranged on the conveyance path 800 in order from upstream to downstream.

The paper feed roller 801, the registration roller 802, and the photosensitive drum 803 are rotationally driven by a paper feed motor 811, a registration motor 812, and a photoconductor motor 813, respectively. Both the fixing roller 804 and the discharge roller 805 are driven to rotate by a common motor 814.
The toner image formed on the outer peripheral surface of the photosensitive drum 803 is electrostatically transferred onto the recording sheet by a transfer roller 831 that rotates following the photosensitive drum 803. The registration sensor 821 and the fixing paper discharge sensor 822 are disposed on the conveyance path 800, upstream of the registration roller 802 and downstream of the fixing roller 804, respectively, and detect the positions of the leading edge and the trailing edge of the recording sheet.

(2) Operation of Engine Controller 301 In the present embodiment, both the fixing roller 804 and the discharge roller 805 are rotationally driven by a common motor 814. For this reason, the number of parts can be reduced and the power consumption can be reduced as compared with the image forming apparatus according to the first embodiment.
However, when the fixing unit jam occurs, if the discharge roller 805 is continuously driven to rotate as in the first embodiment, the recording sheet is wound around the fixing roller, and the jammed recording sheet cannot be taken out. The device may be damaged.

In order to solve such a problem, the engine controller 301 according to the present embodiment determines whether or not to discharge the fixed recording sheet to the outside depending on whether or not the fixing portion jam has occurred.
FIG. 9 is a flowchart showing main operations of the engine controller at the time of jam detection. As shown in FIG. 9, when a jam is detected, the engine controller first stops the rotation of motors other than the common motor 814 (S901).

If the recording sheet on which image formation has been completed is not being discharged (S902: NO), or if the detected jam is a fixing unit jam (S903: YES), the rotation of the common motor 814 is immediately stopped (S905). ), The process is terminated.
If the recording sheet on which image formation has been completed is being discharged (S902: YES) and the detected jam is not a fixing unit jam (S903: NO), the process proceeds to step S904 and a timeout is awaited. As in the first embodiment, a timer is set (not shown) when the fixing paper discharge sensor 822 transitions from the off state to the on state.

Thereafter, when a timeout occurs (S904: YES), the rotation of the shared motor 814 is stopped (S905), and the process is terminated.
In this way, when the detected jam is a fixing unit jam, the rotation of the common motor 14 is immediately stopped, so that the rotation of the fixing roller 804 is stopped, and the paper jam is prevented from deteriorating.

[3] Third Embodiment Next, an image forming apparatus according to a second embodiment of the present invention will be described. The image forming apparatus according to the present embodiment has substantially the same configuration as that of the image forming apparatus according to the second embodiment. On the other hand, even if a fixing unit jam is detected, this may be different depending on the position of the recording sheet. It differs in that it is ejected to reduce missing pages. Hereinafter, the description will be given focusing on the differences.

(1) Internal Structure of Image Forming Apparatus First, the internal structure of the image forming apparatus will be described with particular attention to the transport path for transporting the recording sheet.
FIG. 10 is a cross-sectional view schematically showing a part of the conveyance path of the image forming apparatus. As shown in FIG. 10, a fixing roller 1004, a fixing paper discharge sensor 1022, and a discharge roller 1005 are arranged on the conveyance path 1000 in order from the photosensitive drum 1003 toward the downstream side.

The fixing roller 1004 and the discharge roller 1005 are rotated by a common motor 1014. For this reason, if the common motor 1014 continues to rotate when a fixing unit jam occurs, the fixed recording sheet can be discharged, but jammed paper is wound around the fixing roller 1004.
In particular, if the entire recording sheet from the leading edge to the trailing edge is wound around the fixing roller 1004, it becomes extremely difficult to remove the recording sheet from the fixing roller 1004. For this reason, in order to remove the recording sheet wound around the fixing roller 1004, a part of the recording sheet that is not wound around the fixing roller 1004 must remain to some extent.

  The length of this portion in the recording sheet conveyance direction varies depending on the apparatus configuration. For example, if it is difficult for the operator to reach because the fixing roller 1004 is in the back of the apparatus, the recording sheet cannot be removed unless this portion is long. Conversely, when the fixing roller 1004 is located near the door of the image forming apparatus, the recording sheet may be removed even if it is not so long.

Even when the fixing roller 1004 is close to the door, if the length of the portion of the recording sheet that is not wrapped around the fixing roller 1004 is not less than 5 cm, preferably not more than 10 cm, the operator can grasp the recording sheet well. It is thought that it cannot be removed with
From the above consideration, the distance d1 from the trailing edge of the recording sheet on which image formation has been completed to the discharge roller, the distance d2 from the trailing edge of the recording sheet that is clogging the fixing roller to the fixing roller, and the recording clogged to the fixing roller The sheet length d3 necessary for removing the sheet is
d2-d3> d1
Therefore, even if the recording sheet on which image formation has been completed is discharged out of the apparatus, the recording sheet jammed in the fixing roller remains longer than the paper length d3 without being wound around the fixing roller. Can be removed.

vice versa,
d2-d3 <d1
If the recording sheet on which image formation has been completed is discharged out of the apparatus with the above relationship, the recording sheet wound around the fixing roller cannot be removed. For this reason, the recording sheet on which image formation has been completed should not be discharged outside the apparatus.

(2) Operation of Image Forming Apparatus 10 Next, the operation of the image forming apparatus 10 according to the present embodiment, particularly the operation performed by the engine controller when a jam is detected will be described.
FIG. 11 is a flowchart showing main operations of the engine controller at the time of jam detection. As shown in FIG. 11, when a jam is detected, the engine controller stops the rotation of motors other than the common motor 1014 (S1101). This prevents paper jamming in rollers other than the fixing roller 1004.

If the recording sheet on which image formation has been completed is not being discharged (S1102: NO), the common motor 1014 is immediately stopped (S1106). Even in this case, since the recording sheet that has been fixed does not remain in the apparatus, it is possible to prevent the paper jam in the fixing roller 1004 from deteriorating without worrying about missing pages.
If the recording sheet on which image formation has been completed is being discharged (S1102: YES) and the detected jam is a trouble other than the fixing portion jam (S1103: NO), the common motor 1014 waits for a timeout (S1105: YES). Is stopped (S1106). In this way, since the recording sheet that has been fixed is reliably discharged out of the apparatus, page loss can be prevented.

The fixing unit jam is detected (S1103: YES), and the distances d1, d2, and d3 are d2-d3> d1.
(S1104: YES), the common motor 1014 is stopped (S1106) after waiting for timeout (S1105: YES). In this way, while the recording sheet is wound around the fixing roller 1004 to such an extent that the recording sheet can be removed from the fixing roller 1004, the recording sheet that has been fixed is reliably discharged out of the apparatus. Therefore, page missing can be prevented.

The distances d1, d2, and d3 are d2-d3> d1.
If the relationship is not satisfied (S1104: NO), the common motor 1014 is immediately stopped. In this way, it is possible to prevent the recording sheet from being wound around the fixing roller 1004 and being unable to be removed.

[4] Modifications As described above, the present invention has been described based on the embodiments. However, 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 description has been made by paying attention to the case where a jam has occurred. However, it goes without saying that the present invention is not limited to this. The present invention can be applied to obtain the same effect as described above even when the rotation of the roller is to be stopped due to a cause other than a jam, such as a temperature abnormality of the fixing device.

(2) In the above embodiment, the case where a recording sheet is conveyed using a roller such as a fixing roller or a discharge roller has been described. Needless to say, the present invention is not limited to this. The recording sheet may be conveyed using For example, a fixing belt may be used instead of the fixing roller, and the same applies to other rollers.
(3) In the above embodiment, a case has been described in which the recording sheet on which image formation has been completed is reliably discharged out of the apparatus by waiting for a timeout and stopping the discharge roller. However, the present invention is not limited to this. Needless to say, the recording sheet may be reliably discharged out of the apparatus using other means.

  For example, when estimating the trailing edge position of the recording sheet on the conveyance path, the discharging roller may be stopped after it is estimated that the trailing edge position has surely passed the discharging roller. As described above, the effect of the present invention can be obtained regardless of the method of reliably discharging the recording sheet on which image formation has been completed to the outside of the apparatus.

  The image forming apparatus according to the present invention is useful as an apparatus for preventing missing pages due to a trouble such as a jam.

1 is an external perspective view showing a main configuration of an image forming apparatus according to a first embodiment of the present invention. 2 is a cross-sectional view schematically illustrating a conveyance path of the image forming apparatus 1. FIG. 2 is a block diagram illustrating a control configuration of the image forming apparatus 1. FIG. 3 is a diagram illustrating a communication sequence between an engine controller 301 and an MFP controller 302 at a normal time. FIG. FIG. 5 is a diagram illustrating a communication sequence between an engine controller 301 and an MFP controller 302 when a jam occurs. 6 is a flowchart showing main operations of the MFP controller 302. 3 is a flowchart showing main operations of an engine controller 301. FIG. 6 is a cross-sectional view schematically illustrating a conveyance path of an image forming apparatus according to a second embodiment of the present invention. It is a flowchart which shows the main operation | movement of the engine controller at the time of jam detection. FIG. 10 is a cross-sectional view schematically showing a part of a conveyance path of an image forming apparatus according to a third embodiment of the present invention. It is a flowchart which shows the main operation | movement of the engine controller at the time of jam detection.

Explanation of symbols

1, 8, 10 ............ Image forming apparatus 101 ………………………… Image reading unit 102 …………………… Image forming unit 103 ……………… ………… Paper feed section 104 ………………………… Operation panel 110 ………………………… Front door 111 ………………………… Automatic document feeder 112, 832... ...... discharge trays 200, 800, 1000... Transport path 201, 801..., Feed rollers 202, 802 ............ registration rollers 203, 803, 1003. 204, 804, 1004... Fixing roller 205, 805, 1005... Discharge roller 211, 811... Sheet feeding motor 212, 812. Motor 214 ………………………… Fixing motor 215 …… ………………… Discharge motor 814, 1014 …………… Common motor 221, 821 ……………… Registration sensor 222, 822, 1022… Fixing discharge sensor 231, 831 ……………… Transfer Roller 301 ………………………… Engine controller 302 ………………………… MFP controller 303 ………………………… Image processing unit

Claims (7)

An image forming apparatus that interrupts an image forming job when trouble occurs during execution of the image forming job, and restarts image formation from a page that has not completed image formation after the trouble is solved.
Fixing means for fixing the toner image on the recording sheet;
A discharge means for discharging the recording sheet having the toner image fixed thereon to the outside of the apparatus;
A paper discharge sensor disposed on the recording sheet conveyance path, downstream of the fixing unit and upstream of the discharge unit, and detecting the presence or absence of the recording sheet at the position;
When the trailing edge of the recording sheet passes the paper discharge sensor, a determination unit that determines that the recording sheet has completed image formation;
Detection means for detecting trouble that should interrupt the image forming job;
Estimating means for estimating whether the recording sheet is passing through the discharging means;
If trouble is detected,
If it is estimated that a recording sheet that has not completed image formation is passing through the discharge means, immediately stop the discharge means,
Otherwise, an image forming apparatus comprising: a discharge control unit that stops the discharge unit after the recording sheet passes through the discharge unit. If it is estimated that a recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected, the discharge control means sets the discharge means after a sufficient time to discharge the recording sheet. The image forming apparatus according to claim 1, wherein the image forming apparatus is stopped. If it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected, the discharge control means is estimated that the recording sheet is no longer passing through the discharge means, The image forming apparatus according to claim 1, wherein the discharging unit is stopped. An image forming apparatus that interrupts an image forming job when trouble occurs during execution of the image forming job, and restarts image formation from a page that has not completed image formation after the trouble is solved.
Fixing means for fixing the toner image on the recording sheet;
A discharge unit that is driven by a drive motor common to the fixing unit and discharges the recording sheet on which the toner image is fixed;
A paper discharge sensor disposed on the recording sheet conveyance path, downstream of the fixing unit and upstream of the discharge unit, and detecting the presence or absence of the recording sheet at the position;
When the trailing edge of the recording sheet passes the paper discharge sensor, a determination unit that determines that the recording sheet has completed image formation;
A detecting means for detecting a trouble including a fixing portion jam that is a paper jam in the fixing means and that should interrupt the image forming job;
Estimating means for estimating whether the recording sheet is passing through the discharging means;
When a fixing section jam is detected, and when a trouble other than the fixing section jam is detected and it is estimated that a recording sheet for which image formation has not been completed is passing through the discharge means, Stop the drive motor,
If a trouble other than the fixing section jam is detected and it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means, the drive motor is turned on after the recording sheet passes through the discharge means. An image forming apparatus comprising: a motor control unit that stops. An image forming apparatus that interrupts an image forming job when trouble occurs during execution of the image forming job, and restarts image formation from a page that has not completed image formation after the trouble is solved.
Fixing means for fixing the toner image on the recording sheet;
A discharge unit that is driven by a drive motor common to the fixing unit and discharges the recording sheet on which the toner image is fixed;
A paper discharge sensor disposed on the recording sheet conveyance path, downstream of the fixing unit and upstream of the discharge unit, and detecting the presence or absence of the recording sheet at the position;
When the trailing edge of the recording sheet passes the paper discharge sensor, a determination unit that determines that the recording sheet has completed image formation;
A detecting means for detecting a trouble including a fixing portion jam that is a paper jam in the fixing means and that should interrupt the image forming job;
A specifying means for specifying the trailing edge position of the recording sheet on the conveyance path for each recording sheet;
Estimating means for estimating whether the recording sheet is passing through the discharging means;
When trouble is detected,
If it is estimated that a recording sheet that has not completed image formation is passing through the discharge means, immediately stop the drive motor,
If it is presumed that the recording sheet on which image formation has been completed is passing through the discharging means, and the detected trouble is a trouble other than the fixing unit jam, the drive motor is stopped after the recording sheet has passed through the discharging means. And
In the case where it is presumed that the recording sheet on which image formation has been completed is passing through the discharging means, and the detected trouble is a fixing unit jam,
The distance d1 from the trailing edge of the recording sheet detected immediately before by the paper discharge sensor to the discharging means, the distance d2 from the trailing edge of the recording sheet jammed to the fixing means to the fixing means, and the recording sheet jammed in the fixing means are pulled out. The relationship of the length d3 in the conveyance direction of the recording sheet required for
d2-d3> d1
Then, after the recording sheet has passed through the discharge means, the drive motor is stopped,
d2-d3 <d1
Then, an image forming apparatus comprising: motor control means for immediately stopping the drive motor. When it is estimated that the recording sheet on which image formation has been completed is passing through the discharge means when a trouble is detected, the motor control means is configured to drive the drive motor means after a sufficient time has passed to discharge the recording sheet. The image forming apparatus according to claim 4, wherein the image forming apparatus is stopped. If it is estimated that the recording sheet on which image formation has been completed is passing through the discharging means when a trouble is detected, the motor control means estimates that the recording sheet is no longer passing through the discharging means, 6. The image forming apparatus according to claim 4, wherein the drive motor means is stopped.

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