JP2016038391A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that is excellent in safety and can remove sheets from a fixing roller when an abnormality in the apparatus occurs that does not directly affect sheet conveyance control during printing according to the positional relationship between the fixing roller and sheets.SOLUTION: There is provided an image forming apparatus including a fixing roller 37 for fixing a toner image on a sheet P and a fixing sensor 30 that detects a sheet passed through the fixing roller 37, the image forming apparatus further including control means for, when an abnormality occurs that does not affect conveyance control of the sheet P during printing, driving the fixing roller 37 in reverse rotation or normal rotation to eject the sheet P before removing the sheet P from the fixing roller 37 according to the positional relationship between the fixing roller 37 and sheet P.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus used for, for example, a copying machine, a printer, and a facsimile machine.

  Many multifunction devices and printers are equipped with a control for forcibly stopping the device when an abnormality (such as a paper jam) occurs in the device. This is to prevent the device from running out of control by forcibly stopping it, and to keep the damage to the device to the minimum necessary.

  For example, in Patent Document 1, a means for automatically relieving the pressure with which a fixing roller of a fixing device pinches a sheet, a means for automatically rotating the fixing roller, and a rotating direction of the fixing roller are automatically reversed. And a means for detecting a sheet provided in the vicinity of the fixing roller, and when the sheet stays in the fixing device, the pressure of the fixing roller is automatically relieved, and the sheet is There has been proposed an image forming apparatus that automatically reverses the rotation direction of the fixing roller when the sheet does not move despite the rotation of the fixing roller in an attempt to discharge to the outside of the fixing device.

  Further, in Patent Document 2, print processing for each recording medium that is sequentially fed to a printing mechanism based on print information input from a data processing device via a predetermined communication medium and discharged out of the apparatus from the printing apparatus main body. And a variable control unit that variably sets a conveyance speed for each recording medium fed to the printing mechanism, and is variably set by the variable unit after starting printing processing of each page. A calculation means for calculating a time required for each storage medium fed at a conveyance speed to be ejected from the printing apparatus main body to the outside of the apparatus, a measurement means for measuring an elapsed time from the print processing start time, and The processing state of each page to be printed on each recording medium to be fed is monitored by monitoring whether the elapsed time measured by the measuring unit exceeds the specified time calculated by the calculating unit. Management means for management, printing control apparatus having have been proposed.

JP-A-7-181828 Japanese Patent Laid-Open No. 11-296046

  Although there are various levels of abnormality in the apparatus, there are abnormalities that directly affect the conveyance control and abnormalities that do not directly affect the conveyance control (for example, when the cover door is opened). When an abnormality occurs in the apparatus during printing, if the apparatus is forcibly stopped while ignoring the situation inside the apparatus, the transport sheet may stop on the fixing roller. In Patent Document 1, the fixing roller is rotated in the advancing direction regardless of the paper position, and if it does not move, it is rotated in the reverse direction. In Patent Document 2, although the paper state is determined from the printing start time, printing is performed on each paper. If the process is completed, the paper is discharged and the conveyance is not reversed. As described above, in Patent Document 1 and Patent Document 2, the paper is discharged without considering the positional relationship between the fixing roller and the paper. For this reason, the contact time between the high-temperature fixing roller and the paper becomes long, and the problem of paper burning by the fixing roller cannot be solved.

  The present invention has been made in view of such a point, and the purpose thereof is, in the event of an apparatus abnormality that does not directly affect paper transport control during printing, depending on the positional relationship between the fixing roller and the paper, An object of the present invention is to provide an image forming apparatus that can remove a sheet from a fixing roller and is excellent in safety.

  The present invention relates to an image forming apparatus including a fixing roller for fixing a toner image on a sheet and a fixing sensor for detecting the sheet that has passed through the fixing roller, and an abnormality that does not affect sheet conveyance control during printing. And a control means for removing the paper from the fixing roller after discharging the paper by driving the fixing roller in the reverse or forward rotation according to the positional relationship between the fixing roller and the paper. The gist of the image forming apparatus is as follows.

  According to the present invention, when an abnormality that does not directly affect the sheet conveyance control occurs during printing and forcibly stops, the fixing roller is rotated backward or forward depending on the positional relationship between the fixing roller and the sheet. By controlling to remove the paper by driving, the time for the fixing roller and the paper to contact can be minimized. Therefore, it is possible to suppress the burning of the sheet due to the temperature abnormality of the fixing roller, and the safety is excellent.

1 is a perspective view illustrating an external appearance of a multifunction peripheral according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a main part of a multifunction machine according to an embodiment of the present invention. FIG. 6 is a schematic diagram illustrating a case where the leading edge of a sheet is in contact with a fixing roller. FIG. 6 is a schematic diagram illustrating a case where a sheet other than the leading edge of the sheet is in contact with the fixing roller. FIG. 6 is a schematic diagram illustrating a case where a sheet is crumpled by a fixing roller. FIG. 6 is a schematic diagram illustrating a case where a fixing roller and a sheet are not in contact with each other. FIG. 6 is a schematic diagram illustrating a case where a fixing roller and a sheet are not in contact with each other.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, as an image forming apparatus according to the present invention, an electrophotographic multifunction machine having functions such as a copier, a printer, and a facsimile machine will be described as an example.

<Schematic configuration of MFP 10>
With reference to FIGS. 1 and 2, a schematic configuration of a multifunction machine 10 according to an embodiment of the present invention will be described. As shown in FIGS. 1 and 2, the multifunction machine 10 includes an image reading unit 1, an operation display unit 2, an image forming unit 3, a paper feed cassette 4, and a control unit 5. An automatic document feeder (ADF) that automatically conveys a document is mounted on the upper part of the image reading unit 1, but illustration and description thereof are omitted in the present embodiment.

  The image reading unit 1 is an image reading unit including an optical system such as a lens and a mirror and an image pickup device such as a charge coupled device (CCD) or a contact image sensor (CIS). The image reading unit 1 executes image reading processing for reading image data from a document placed on the contact glass 11 or a document conveyed by an automatic document feeder.

  The operation display unit 2 is a display unit such as a liquid crystal panel that displays various types of information in accordance with a control instruction from the control unit 5, an operation unit that inputs an operation signal to the control unit 5 in response to a user's touch operation on the display unit, and the like. Has a touch panel.

  The image forming unit 3 is an electrophotographic system that executes image forming processing (printing processing) based on image data read by the image reading unit 1 or image data input from an information processing apparatus such as an external personal computer. Image forming means.

  Specifically, as shown in FIG. 2, the image forming unit 3 includes a photosensitive drum 31, a charging device 32, an exposure device (LSU) 33, a developing device 34, a transfer roller 35, a cleaning device 36, a fixing roller 37, A pressure roller 38, a waste toner container 39, and the like are provided.

  On the other hand, each of the paper feed cassettes 4 stores a plurality of sheets, and the sheets stored in each of the sheet feed cassettes 4 are passed through the image forming section 3 and the discharge rollers 6 by a sheet transport section 41 having a plurality of transport rollers. Then, it is conveyed to the paper discharge tray 43. The paper transport unit 41 includes a drive unit 42 that includes one or a plurality of drive motors that drive the transport rollers. Each of the transport rollers of the paper transport unit 41 is rotationally driven by a driving force transmitted from the drive unit 42 via a transmission system such as a gear.

  In the image forming unit 3, an image forming process is performed on the paper supplied from the paper feed cassette 4 in the following procedure. First, the photosensitive drum 31 is uniformly charged to a predetermined potential by the charging device 32. Next, the exposure device 33 irradiates the surface of the photosensitive drum 31 with light based on the image data. Thereby, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 31. The electrostatic latent image on the photosensitive drum 31 is developed (visualized) as a toner image by the developing device 34. The developing device 34 is supplied with toner (developer) from a toner container 34 </ b> A that can be attached to and detached from the image forming unit 3. Subsequently, the toner image formed on the photosensitive drum 31 is transferred onto a sheet by the transfer roller 35. Thereafter, the toner image transferred to the sheet is heated and fixed by the fixing roller 37 when the sheet passes between the fixing roller 37 and the pressure roller 38.

  On the other hand, the toner remaining on the surface of the photosensitive drum 31 after the image forming process by the image forming unit 3 is removed by the cleaning device 36. The toner removed by the cleaning device 36 is discharged as waste toner and stored in the waste toner storage unit 39.

  In the MFP 10 according to the present embodiment, when an abnormality that does not directly affect the sheet conveyance control occurs during printing, the apparatus 10 is controlled to forcibly stop the apparatus in order to prevent the apparatus from running away and minimize damage to the apparatus. Is provided.

  In the present embodiment, after the forced stop due to the occurrence of an abnormality, the following (1) to (4) are controlled to remove the sheet from the fixing roller according to the positional relationship between the four types of fixing rollers and the sheet.

(1) When the leading edge of the paper is in contact with the fixing roller (paper position detection)
FIG. 3 shows a case where the leading edge of the paper P is in contact with the fixing roller 37. The upward direction in the drawing indicates the conveyance direction of the paper P. The fixing sensor 30 is an optical sensor that detects the paper P that has passed through the fixing roller 37, and is provided between the fixing roller 37 and the paper discharge roller 6 (see FIG. 2), and detects the paper P that has passed through the fixing roller 37. When detected, a detection signal is output to the control unit. The position of the paper P is detected using a timer using a sensor (not shown) located upstream (lower side of the drawing) from the fixing roller 37 as a trigger. When the sheet P is in contact with the fixing roller 37 and the fixing sensor 30 downstream (upper side of the drawing) from the fixing roller 37 is OFF, it is detected that the leading edge of the sheet P is in contact with the fixing roller 37. . In the present specification, not only the front end of the paper P but also the vicinity of the front end of the paper P is simply referred to as “front end”.

(Behavior after forced stop)
After the forced stop due to the occurrence of an abnormality, only the fixing roller 37 is driven to rotate in the reverse direction, and no other rollers are driven. The time for driving the fixing roller 37 is a time necessary for removing the paper P from the fixing roller 37. Thereafter, the user is notified to manually remove the paper P.

  Since the leading edge of the paper P is in contact with the fixing roller 37, when the fixing roller 37 is driven to rotate in the forward direction and the paper P is to be removed as in the conventional case, the transported paper P contacts the fixing roller 37. There is a possibility that the paper P may burn due to the time being increased and the temperature of the fixing roller 37 being abnormal. According to the present embodiment, since the time when the fixing roller 37 and the paper P are in contact with each other can be minimized by rotating the fixing roller 37 in the reverse direction, the temperature of the fixing roller 37 is abnormal. It is possible to suppress the burning of the paper P due to this, and it is excellent in safety.

(2) When other than the leading edge of the paper is in contact with the fixing roller (paper position detection)
FIG. 4 shows a case where the fixing roller 37 is in contact with other than the leading edge of the paper P. The position of the paper P is detected using a sensor (not shown) upstream (lower side of the drawing) of the fixing roller 37 or a fixing sensor 30 downstream (upper side of the drawing) as a trigger. When the paper P is in contact with the fixing roller 37 and the fixing sensor 30 is ON, it is detected that the part other than the leading edge of the paper P is in contact with the fixing roller 37.

(Behavior after forced stop)
After the forced stop due to the occurrence of an abnormality, all the rollers (such as the discharge roller) located downstream (upward in the drawing) from the fixing roller 37 are driven to rotate in the forward direction to discharge the paper P. In order not to convey the succeeding paper P that is not in contact with the fixing roller 37 to the fixing roller 37, a roller (such as a registration roller) upstream (lower side of the drawing) from the fixing roller 37 is not driven. The time for driving the discharge roller or the like is a time necessary for completing the discharge of the paper P from the position of the paper P (a time required for removing the paper P from the fixing roller 37). Thereafter, the user is notified to manually remove the paper P.

<Modification>
When the MFP 10 according to the present embodiment is provided with a humidity sensor or a media sensor that can acquire the moisture content of the paper P, the paper P can be burned by the fixing roller 37 from an environment such as humidity or the moisture content of the paper P. If the conditions are high, depending on the paper position, it is faster to reversely rotate the fixing roller 37 as in (1) when the leading edge of the paper P is in contact with the fixing roller 37 described above. If it can be determined that P can be removed from the fixing roller 37, only the fixing roller 37 may be reversely rotated.

(3) When the paper is crumpled by the fixing roller (paper position detection)
FIG. 5 shows a case where the paper P is crumpled by the fixing roller 37. The position of the paper P is estimated using a sensor upstream (lower side of the drawing) from the fixing roller 37 as a trigger. From the estimated position of the paper P, the fixing sensor 30 that is normally downstream (upper side of the drawing) from the fixing roller 37 is ON (when the paper P is on the fixing sensor 30). When 30 is OFF (when there is no sheet P on the fixing sensor 30), it can be determined that the sheet P is likely to be crumpled by the fixing roller 37 as shown in FIG.

(Behavior after forced stop)
After the forced stop due to the occurrence of an abnormality, the drive motors of all the rollers including the fixing roller 37 are stopped, and the user is notified to manually remove the paper P.

  When the fixing roller 37 is driven in a state where the paper is crumpled, it is conceivable that the paper P is caught in the fixing roller 37, but in this embodiment, all the drive motors are stopped. Such paper P is not caught.

(4) When the fixing roller is not in contact with the paper (paper position detection)
6 and 7 show a case where the fixing roller 37 and the paper P are not in contact with each other. The position of the paper P is estimated by using the sensor upstream (lower in the drawing) of the fixing roller 37 or the fixing sensor 30 downstream (upper in the drawing) as a trigger, and the paper P is not in contact with the fixing roller 37. Judge.

(Behavior after forced stop)
After the forced stop due to the occurrence of an abnormality, the drive motors of all the rollers including the fixing roller 37 are stopped, and the user is notified to manually remove the paper P.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the description of the above-described embodiment but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The image forming apparatus of the present invention can be applied to, for example, a copying machine, a printer, and a facsimile machine.

10 MFP (an example of an image forming apparatus)
30 Fixing sensor 37 Fixing roller P Paper

Claims (3)

An image forming apparatus comprising: a fixing roller for fixing a toner image on a sheet; and a fixing sensor for detecting the sheet that has passed the fixing roller;
If an abnormality that does not affect the paper transport control occurs during printing, the paper is discharged from the fixing roller after the fixing roller is driven in reverse or forward rotation according to the positional relationship between the fixing roller and the paper. An image forming apparatus comprising a control means for removing the image. The image forming apparatus according to claim 1.
If the leading edge of the paper is in contact with the fixing roller, drive only the fixing roller in the reverse direction to run the paper backward, then remove the paper from the fixing roller,
If the paper other than the leading edge of the paper is in contact with the fixing roller, all the rollers located downstream from the fixing roller are driven to rotate in the forward direction to discharge the paper, and then the paper is removed from the fixing roller.
If the paper is crumpled by the fixing roller, remove the paper from the fixing roller with all the rollers including the fixing roller stopped.
An image forming apparatus, wherein when a sheet is not in contact with a fixing roller, the sheet is removed from the fixing roller in a state where driving of all rollers including the fixing roller is stopped. The image forming apparatus according to claim 1, wherein
If a humidity sensor or a media sensor that can acquire the moisture content of the paper is provided, and the conditions that the paper is likely to burn by the fixing roller from the humidity or moisture content of the paper are met,
Even when the fixing roller is in contact with a part other than the leading edge of the paper, only the fixing roller is driven in the reverse rotation so that the paper runs backward, and then the paper is removed from the fixing roller. apparatus.

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