JP5359836B2 - Image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming system having a plurality of fixing apparatuses, and efficiently and economically cleaning the fixing apparatus by using a blank sheet. <P>SOLUTION: The image forming system is configured to allow, when there is a possibility that a sheet is retained in any of the plurality of fixing apparatuses, a user to select whether to clean the fixing apparatus by using a blank sheet by visually confirming how a fixing device is contaminated by toner in handling paper jam. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic image forming system, and more particularly to an image forming system capable of performing efficient blank paper cleaning on a plurality of fixing devices.

  In an electrophotographic image forming system, a toner image formed on a photoconductor is transferred onto a sheet and fixed by a fixing device. The most commonly used fixing method is a roller fixing method in which a sheet is sandwiched between a heating roller and a pressure roller (collectively referred to as a fixing roller) and heated and pressed.

  As a modification of the heat roller system, a belt fixing system in which at least one of a heating roller and a pressure roller is formed of a belt is often used. The belt is used for the purpose of improving the heating efficiency and expanding the area of the nip portion. In the present invention, a member that forms a nip portion such as a heating roller and a pressure roller, or a belt is collectively referred to as a fixing member.

  When the paper jams in the nip portion of the roller fixing system or the belt fixing system, the toner carried on the paper adheres to the fixing member even after the jam processing, and when image formation is resumed, The image forming surface and the back surface may be contaminated.

  If the fixing device is provided with a cleaning device, it is possible to clean such contaminated toner, but in recent years there are many device configurations in which jamming is less likely to occur by mixing a wax having good releasability into the toner component, In such a case, a cleaning device is often not provided.

  However, if a jam occurs in a fixing device that does not have a cleaning device, or if a jam occurs in a conveyance path other than the fixing device and a sheet carrying unfixed toner stays in the nip portion of the fixing device, the above contaminated toner Adhesion occurs and becomes a problem. Since the fixing device becomes high temperature, it is not preferable for the safety measures to leave the user to clean.

  Therefore, when the fixing device is contaminated due to a jam or the like, a proposal has been made to pass the cleaning sheet through the nip portion of the fixing device and clean the fixing device with this cleaning sheet. For example, in Japanese Patent Application Laid-Open No. H11-228707, when a jam or the like occurs, if there is a possibility that a sheet is held in the nip portion of the fixing device, an image is not formed in the nip portion of the fixing device during automatic paper discharge after the jam processing. A technique for passing paper is disclosed.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for increasing the cleaning efficiency by passing the cleaning sheet through the nip portion of the fixing device and performing the cleaning to make the conveying speed slower than that at the time of image formation.

  The cleaning sheet may be an unused white paper, the back of the printed paper, or a paper on which an image suitable for cleaning the toner attached to the fixing roller is used. In the present invention, such cleaning methods for passing various types of paper through the fixing device are collectively referred to as blank paper cleaning or cleaning paper passing.

  On the other hand, some image forming systems include a plurality of fixing devices. The fixing device applies heat to the paper to fix the toner, but on the other hand, the paper is deprived of heat. For this reason, if a material having a large heat capacity is used for the roller of the fixing device, the paper is heated from the roller. Although the temperature drop of the roller due to the removal is reduced, there is a disadvantage that it takes time to raise the temperature lowered by warm-up or paper passing. Therefore, a plurality of fixing devices are arranged in series to share the fixing process.

  For example, in Patent Document 3, three fixing devices are arranged in series, and each fixing device is provided with a mechanism for pressing and releasing the nip portion, and the fixing device to be used is switched according to a temperature drop, a predetermined number of sheets to be passed, or the like. The technology is disclosed.

  Further, in Japanese Patent Laid-Open No. 2004-260688, in consideration of the fact that the image gloss can be adjusted by changing the amount of heat applied to the paper during fixing, a plurality of fixing devices are arranged in series, and the number of fixing devices to be used is switched to control the image gloss. The technology is disclosed.

  Furthermore, by arranging a plurality of fixing devices in parallel, for example, by passing sheets to each fixing device alternately and using them properly, the heat capacity required for one fixing device is reduced, and the time required for warming up the fixing device is reduced. A shortening is also considered (Patent Document 5). In such a configuration, since the interval between sheets passing through the individual fixing devices is widened, the frequency of heat being taken away by the sheet can be reduced, and for example, fixing ability can be secured without reducing productivity even with thick paper.

  However, in such an image forming system in which a plurality of fixing devices are arranged in series or in parallel, how to perform blank paper cleaning when a jam occurs has not been proposed yet.

JP 2003-98888 A JP 2005-3784 A JP 2000-221820 A JP 2000-221821 A Japanese Patent Application Laid-Open No. 2000-221834

  If the blank paper cleaning of Patent Documents 1 and 2 is applied as it is to an image forming system in which a plurality of fixing devices are arranged, blank paper cleaning is uniformly performed on the plurality of fixing devices, but such a cleaning process is inefficient. It is uneconomical.

  Even if the paper stays in the fixing device, the degree of toner contamination due to the stay varies greatly depending on the state of image formation. For example, in the case of an image with a low printing rate, toner contamination hardly occurs, and even if it occurs, it may be at a level acceptable for some users. Since it is difficult to detect the degree of toner contamination by measurement, blank paper cleaning is performed uniformly. However, it is uneconomical to automatically perform blank paper cleaning even when cleaning is unnecessary.

  Therefore, in view of the fact that the user can visually check the degree of toner contamination on the fixing member when the jam processing is performed, the present invention does not perform unnecessary blank paper cleaning by selecting whether or not to perform blank paper cleaning. An object is to provide a forming system.

The above object of the present invention can be achieved by the following constitution.
1. A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Whether to execute the blank cleaning possess a selection means for selecting a user, the after jam processing,
The image forming system according to claim 1, wherein the selection unit displays a display selection screen for selectively displaying whether or not to perform blank paper cleaning for each fixing device .
2. A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Selection means for allowing the user to select whether or not to perform blank paper cleaning after the jam processing,
The image forming system according to claim 1, wherein the selection unit displays, as a default, a display indicating that blank paper cleaning is to be performed on a fixing device in which paper may have accumulated.
3. A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Selection means for allowing the user to select whether or not to perform blank paper cleaning after the jam processing,
The selection unit displays a sheet number display screen for displaying the number of sheets to be passed when performing blank sheet cleaning, and displays the number of sheets depending on whether the number of fixing devices in which the sheet may stay is one or more. An image forming system that controls to change a default number of sheets to be displayed on a screen.
4 . 4. The image forming system according to 2 or 3 , wherein the selection unit displays a display selection screen for performing alternative display as to whether or not to perform blank paper cleaning for each fixing device.
5 . 4. The image forming system according to 1 or 3 , wherein the selection unit displays, as a default, a display indicating that blank paper cleaning is to be performed on a fixing device in which paper may have accumulated.
6 . The selection unit displays a sheet number display screen for displaying the number of sheets to be passed when performing blank sheet cleaning, and displays the number of sheets depending on whether the number of fixing devices in which the sheet may stay is one or more. 3. The image forming system as described in 1 or 2 above, wherein control is performed to change the default number of sheets to be displayed on the screen.
7). The selection unit displays whether or not to perform blank sheet cleaning when the sheet retention determination unit determines that there is a possibility that the sheet has accumulated in at least one fixing device. 7. The image forming system according to any one of items 6.
8 . Said selection means displays the paper setting screen that displays the type of paper, from above, wherein the controller controls so as to selectably displays the type of paper available blank cleaned from the paper setting screen 7 The image forming system according to any one of the above.
9 . 9. The image forming system according to 8 , wherein the selection unit displays the sheet type to be displayed in a selectable manner with reference to the sheet type used in the job before the occurrence of the jam.
10 . The image forming system according to any one of 1 to 9 , wherein the selection unit includes a display selection screen configured by a touch panel.
11 . 11. The image forming system according to any one of 1 to 10 , wherein the blank paper cleaning control unit allows a sheet used for cleaning to pass through without forming an image by the image forming unit.

  The present invention eliminates the need for the user to select whether or not to perform blank paper cleaning and to determine which fixing device to perform blank paper cleaning by visually checking the toner contamination level of the fixing member when the jam processing is performed by the user. The present invention has an effect of providing an economical image forming system that does not perform clean white paper cleaning.

1 is a central sectional view of an image forming system to which the present invention is applied. FIG. 3 is a schematic diagram around the fixing device illustrating the present invention. FIG. 4 is a diagram illustrating a situation where jammed paper is retained in the first fixing device in the present invention. FIG. 4 is a diagram illustrating a situation where jammed paper is retained in a second fixing device in the present invention. The block diagram which shows the control structure of a semi-invention. The flowchart which shows control of the Example of this invention. The flowchart which shows control of the Example of this invention. The figure which shows the operation panel which concerns on this invention. The figure which shows the operation panel which concerns on this invention. The figure which shows the operation panel which concerns on this invention.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a central sectional view of an image forming system to which the present invention is applied, and this image forming system is a tandem type color machine. Needless to say, the present invention can be applied to other types of color machines, monochrome machines, and the like.

  The image forming system includes a central image forming apparatus GS, an automatic document feeder YS placed thereon, and a second fixing unit TU. These are configured separately and assembled at the installation location of the system, but may be integrated.

  The image forming apparatus GS has an intermediate transfer belt 1 wound vertically in the center, and a yellow image forming unit 2Y, a magenta image forming unit 2M, a cyan image forming unit 2C, a black image on the right side of the intermediate transfer belt 1. The image forming units 2B are arranged in order from the top.

  Since the configuration of each image forming unit is the same, only the yellow image forming unit 2Y will be described. The photosensitive drum 3Y is disposed at the left end of the unit so as to be in contact with the intermediate transfer belt 1, and around this photosensitive drum 3Y. In the counterclockwise direction, the charging device 4Y, the laser writing device 5Y, the developing device 6Y, the primary transfer roller 7Y (the back side of the intermediate transfer belt 1), and the cleaning device 8Y are sequentially arranged. In the following description, the part numbers obtained by taking Y, M, C, and K of each device are descriptions common to the respective colors.

  An image reading device IR is arranged below the automatic document feeder YS, and an image of the document fed to the reading position by the automatic document feeder YS or an image of a document placed on the document glass is read by the image reader. The IR is read and supplied to the laser writing device 5.

  After the photosensitive drum 3 is uniformly charged by the charging device 4, an image is written by the laser writing device 5, and an electrostatic latent image is formed on the photosensitive drum 3. The electrostatic latent image is converted into a toner image by the developing device 6 and transferred to the intermediate transfer belt 1 by the primary transfer roller 7.

  When the toner images of the respective colors are superimposed on the intermediate transfer belt 1, the toner images are transferred onto the paper fed from the paper feeding device 10 by the secondary transfer roller 9. The intermediate transfer belt 1 after the transfer is cleaned by a belt cleaning device 11.

  The toner image transferred to the paper is fixed by a fixing device. The illustrated image forming system includes a first fixing device 20a and a second fixing device 20b arranged in series, and the second fixing device 20b is arranged in the above-described second fixing unit TU.

  Two fixing devices are provided in order to achieve sufficient fixing performance by applying sufficient heat and pressure to the paper and to speed up the warm-up time rather than obtaining the same effect with one fixing device. Also, giving sufficient heat and pressure to the paper leads to an increase in glossiness.

  Both fixing devices 20a and 20b have upper fixing belts 21a and 21b and lower pressure rollers 22a and 22b, respectively. The fixing belts 21a and 21b are wound around support rollers 23a and 23b and heating rollers 24a and 24b, respectively, and a heater is disposed in the heating rollers 24a and 24b. The fixing temperature of each fixing device is controlled to a different fixing temperature depending on the image forming mode, as will be described later. Also, the temperature is controlled to be different in the blank paper cleaning according to the present invention.

  Next, the paper conveyance path will be described. The paper feeding device 10 has three stages of paper feeding trays and accommodates papers of different sizes, paper thicknesses, and paper types. The selected paper is sent out by each paper feed roller, reaches the transfer position through the first transport path Ra, and the toner image is transferred. The sheet on which the toner image is transferred travels to the first fixing device 20a through the second transport path Rb.

  A conveyance path switching member 30 is provided in the conveyance path between the first fixing device 20a and the second fixing device 20b, and any of the straight conveyance path Rc toward the second fixing apparatus 20b and the bypass conveyance path Rd downward. Make the crab paper face.

  A conveyance path switching member 31 is provided in the conveyance path downstream of the second fixing device 20b, and the sheet is fed to either the straight conveyance path Re from the discharge roller 12 toward the discharge tray 13 or the bypass conveyance path Rf downward. Let go.

  A conveyance path switching member 32 is provided in the bypass conveyance path Rd, and branches into a bypass discharge path Rg and a bypass inversion path Rh. The bypass discharge path Rg joins the bypass conveyance path Rf extending downward from the second fixing device 20b, and discharges the sheet from the discharge roller 12 to the discharge tray 13. That is, the bypass conveyance path Rf is configured to be driven in the arrow X direction for returning the paper from the second fixing device 20b and in the arrow Y direction for discharging the paper from the first fixing device 20a.

  On the other hand, the bypass inversion path Rh joins the inversion path Ri below the bypass inversion path Rh. Further, the sheet traveling in the direction of arrow Y along the bypass transport path Rf travels along the bypass transport path Rj via the transport path switching member 33 provided at the branch point, and further joins the reversing path Ri. The sheet that has entered the reversing path Ri advances until the trailing edge completely enters the reversing path Ri, and then is driven in the opposite direction to travel along the double-sided conveying path Rk to join the first conveying path Ra, and the back side of the sheet. The toner image is transferred to the surface.

  In addition, a plurality of paper sensors SS (indicated by a symbol ▲ in FIG. 1) are arranged in the paper conveyance path, and whether or not the paper has reached the paper sensor SS at a predetermined time. Jam is discriminated based on whether or not it has passed the paper sensor SS. In addition, it is possible to detect in which part of the conveyance path a sheet other than the jammed sheet is retained by the sheet sensor SS.

  From the viewpoint of the present invention, since it is detected that the paper stays in the fixing device, it is directly detected whether or not the paper is staying in the nip portion of the fixing device in addition to the paper sensor arrangement of normal jam detection. It is also possible to provide a stagnation sensor.

  In the present invention, the detection of the paper sensor SS determines whether or not there is a possibility that the paper has stayed in the nip portion of each fixing device when a jam occurs, and controls blank paper cleaning based on this determination.

When the paths of the paper discharged from the first fixing device 20a described above passing through the above-described conveyance path are summarized for the single-side mode and the double-side mode,
Direct discharge on one side ... 20a → Rc → 20b → Re
Single-sided bypass discharge 20a → Rd → Rg → Rf → Re
First double-sided transport direct discharge ...
20a → Rd → Rh → Ri → Rk → Ra → Rb → 20a → Rc → 20b → Re
First double-sided conveyance bypass discharge
20a → Rd → Rh → Ri → Rk → Ra → Rb → 20a → Rd → Rg → Rf → Re
Second double-sided transport direct discharge ...
20a → Rc → 20b → Rf → Rj → Ri → Rk → Ra → Rb → 20a → Rc → 20b → Re
Second double-sided conveyance bypass discharge
20a → Rc → 20b → Rf → Rj → Ri → Rk → Ra → Rb → 20a → Rd → Rg → Rf → Re
There are six ways.

  Here, the direct discharge is a conveyance mode in which the paper is discharged after being fixed by both the first fixing device 20a and the second fixing device 20b, and the bypass discharge is fixed by only the first fixing device 20a. This is a transport mode in which the sheet is discharged after being received.

  The first double-sided conveyance is a mode in which the front side of the sheet is fixed only by the first fixing device 20a and then returned to the double-sided conveyance path in order to form an image on the back side in the double-sided mode. In the double-sided mode, the sheet surface is fixed by both the first fixing device 20a and the second fixing device 20b and then returned to the double-sided conveyance path. Further, in the double-side mode, a combination of either direct discharge or bypass discharge is made according to the type of paper.

  Selection of such a conveyance path is performed by a combination of the single-sided / double-sided mode and the paper thickness, type, and the like.

  The paper thickness and type of paper are selected based on the following criteria, for example.

  Basically, in the duplex mode, only the first fixing device passes through the front surface, and both the first and second fixing devices pass through the back surface. This is because the front surface is further heated at the time of fixing the back surface, and there is no problem even if the fixing is so gentle that the toner does not peel off.

  Regarding the standard of the paper thickness and type, when the paper is thick, both the first and second fixing devices are passed, but when the paper is thin, only the first fixing device is passed. This is because thin paper has a small heat capacity and can be sufficiently fixed only by the first fixing device. Further, when the paper type is label paper or OHP, passing both of the two fixing devices may damage the paper. In such a case, fixing is performed only by the first fixing device.

  In the embodiment of the present invention, the combination of the switching of the conveyance path according to the paper thickness and type of the paper as described above and the control of the fixing temperature of the first fixing device 20a and the second fixing device 20b is the best. It is configured so as to have a good fixing effect. Table 1 shows examples of fixing temperatures of the first and second fixing devices depending on the paper thickness and the paper type.

  In Table 1, for paper with a large paper thickness (basis weight), the fixing temperature of the first fixing device is set high, and the paper type is divided into coated paper and others, and the coated paper is used. The fixing temperature is set low. Since the coated paper is coated with a paint on the surface of the paper, the fixing temperature is slightly lower than that other than the coated paper so that the heat due to fixing does not adversely affect the paper.

  Further, the fixing temperature of the second fixing device is set lower than the fixing temperature of the first fixing device. This is because the first fixing device is set to a temperature at which sufficient fixing can be performed since all the sheets are passed, whereas the second fixing device complements the fixing of the paper fixed by the first fixing device. Since it has a function and a function of increasing the glossiness as a finish, it is set as described above.

  In the image forming system described above, control of blank paper cleaning after jam processing when a jam occurs will be described.

  FIG. 2 is a diagram schematically showing the surroundings of the two fixing devices 20a and 20b according to the present invention, and shows a state in which the jam is generated in the second fixing device 20b and the device is stopped. When the apparatus stops, the sheet P1 upstream of the jammed paper J1 is also shown as being stopped at the position of the first fixing device 20a. A sheet P on which an image is not yet formed also stays upstream of the sheet P1.

  At this time, the unfixed toner on the jammed paper J1 is pressed against the fixing belt to contaminate the fixing belt, and the unfixed toner on the paper P1 that is not jammed but stays in the nip portion of the second fixing device. Is also attached to the fixing belt.

  Even if the user removes the paper J1, P1, and P by jamming from such a state, the toner adhering to the fixing belt remains as it is, and the newly fed paper is contaminated when image formation is resumed. Therefore, blank paper cleaning is performed to remove the toner adhering to the fixing belt.

  In the present invention, the fixing temperature for blank paper cleaning is different from the fixing temperature for image formation. In other words, blank paper cleaning is performed when the temperature of the first fixing device 20a and the second fixing device 20b reaches the following temperature, but the paper stays instead of waiting for the temperatures of both the fixing devices to reach the following temperatures. When the temperature of the fixing device, that is, the fixing device that performs the white paper cleaning, reaches the following white paper cleaning permission temperature, the white paper cleaning is started.

First fixing device 20a 180 ° C.
Second fixing device 20b 165 ° C.
FIG. 3 shows a state where jammed paper stays in the first fixing device 20a, and FIG. 4 shows a state where jammed paper stays in the second fixing device 20b. When the paper stays in the first fixing device 20a, the white paper cleaning is started when the temperature of the first fixing device 20a reaches 180 ° C., and the second fixing device 20b does not require cleaning. The cleaning paper is discharged by the route.

  On the other hand, when the paper stays in the second fixing device 20b, the first fixing device 20a does not need to be cleaned. Therefore, even if the temperature of the first fixing device 20a does not reach 180 ° C., the second fixing device 20b When the temperature reaches 165 ° C., blank paper cleaning is started. The path of the conveyance path at this time is direct discharge on one side.

  FIG. 5 is a block diagram schematically showing a control configuration for performing the control of the present invention. The control means CU includes a known CPU, memory, IO gate, and the like. The control means CU includes a conveyance path. Signals from a plurality of sheet sensors SS provided in the first and second fixing temperature adjusting circuits TC1, TC2, and a plurality of conveying path switching members 30, 31, 32, 33 provided in the conveying path are input. A control signal is output to each conveyance path switching solenoid SL that activates.

  The first fixing temperature adjustment circuit TC1 and the second fixing temperature adjustment circuit TC2 include a temperature sensor (not shown) that measures the temperature of each fixing device, and the temperature is measured based on the temperature measured by the temperature sensor. Tones.

  Further, an operation panel SP is connected to the control means CU, receives an input signal from the operation panel SP, and outputs a signal having contents to be displayed. The control unit CU is connected to various devices, sensors, and the like (not shown) for controlling the entire image forming system, but FIG. 5 shows only those related to the present invention.

  FIGS. 6 and 7 are flowcharts showing a control program from the occurrence of a jam to the blank sheet cleaning according to the first embodiment of the present invention performed by the control means CU. Note that terms in the flowchart are simplified.

  Note that the sheet staying determination unit, the blank sheet cleaning control unit, and the selection unit described in the claims include a corresponding functional portion of the control program and related sensors, devices, operation panels, and the like.

  When a jam occurs, this program is entered, and the apparatus is first stopped in step S01. Then, it is determined from the signal from the paper sensor SS at the time of stop whether or not the paper is staying in the first fixing device 20a (step S02). If there is a paper, the first fixing paper remaining flag Fs1 is set (step S02). S03). If there is no sheet, the first fixing sheet remaining flag Fs1 is cleared (step S04).

  Similarly, it is determined whether or not a sheet remains in the second fixing device 20b, and the second fixing sheet remaining flag Fs2 is set and cleared according to the presence or absence of the sheet (steps S05 to S07).

  Next, in step S08, the process waits for the user to complete the jam processing, and when completed, temperature control of the first fixing device 20a and the second fixing device 20b is started. At this time, the control unit CU outputs the above-described blank sheet cleaning permission temperature to the first fixing temperature adjustment circuit TC1 and the second fixing temperature adjustment circuit TC2, and controls the temperature.

  Subsequently, in step S10, it is determined whether either the first fixing sheet remaining flag Fs1 or the second fixing sheet remaining flag Fs2 is set. If either is set, the operation panel of step S11 is determined. The display selection control subroutine is proceeded to. If it is not set in any fixing device, the process proceeds from B to B, and this program is terminated.

  The display selection control subroutine in step S11 confirms with the user on the operation panel SP whether or not to perform blank sheet cleaning, which fixing device to perform blank sheet cleaning, and the number and type of sheets used for blank sheet cleaning. It is a subroutine. The confirmation result of the user is determined by this subroutine and used for the control in this routine shown in FIGS.

  Since the user can visually check the contamination state of the fixing device during the jam processing, when the contamination is hardly generated, the user can move to normal image formation without performing blank paper cleaning.

  Confirmation of whether or not to perform blank paper cleaning is performed by displaying D1 “Do you want to perform cleaning paper?” On the operation panel SP shown in FIG. 8 and “Yes” or “No” button display D2 on the touch panel. And done.

  Note that the screen in FIG. 8 is displayed in step S10 when it is determined whether either the first fixing sheet remaining flag Fs1 or the second fixing sheet remaining flag Fs2 is set. If a jam occurs, you can always display it.

  When a jam is detected by a normal paper sensor instead of the stay sensor that detects the stay of paper in the fixing device itself, the control unit determines that the paper has stayed in the fixing device by the placement of the paper sensor. In some cases, the sheet may actually be contaminated with the fixing device. Alternatively, this is effective when a user performs jam processing and visually observes the fixing device and the fixing member has been contaminated in the past fixing operation, and it is desired to perform blank paper cleaning.

  Returning to the explanation of FIG. 8, when the “Yes” button is pressed, the screen shifts to the display screen of the operation panel SP of FIG. 9, and the message “Which fixing device do you want to pass the cleaning paper?” In the display D3, the user confirms the fixing device that performs blank paper cleaning. On the confirmation display screen, a “Yes” and “No” button D4 is displayed for each fixing device, and a “Yes” button is displayed as a default display for a fixing device in which paper may remain. Is done. In FIG. 9, black-filled and white buttons are the default display.

  When any “Yes” button is pressed, the display screen shown in FIG. 10 is displayed, and the number and type of sheets used for blank paper cleaning are confirmed with the user. This confirmation is made with a display D5 of “Perform cleaning paper. Please select the number of sheets and paper.”

  On the right side of the display D5, a default value D6 of the number of sheets used for blank sheet cleaning is displayed. When changing the default value, the user changes the default value by inputting the number from a numeric input key (not shown) arranged on the side of the operation panel SP or the like.

  This default value is configured to display an appropriate number of sheets according to the fixing device in which the sheet may stay. For example, when there is a possibility that the paper stays in two fixing devices, five sheets, and when there is a possibility that the paper stays in the first fixing device 20a on the upstream side, three sheets are provided on the downstream side. 2 When there is a possibility that the sheet stays in the fixing device 20b, two sheets are displayed. The user may correct this default value to an appropriate value by judging from the degree of contamination of the fixing device visually.

  A screen for selecting various settings is displayed below the display D5. This display is performed so that only the items that can be selected by the user can be identified. That is, the button portion represented by a dot pattern cannot be selected by the user, and the button portion represented by white can be selected. For example, since no image is formed in the color setting area, all the buttons cannot be selected.

  In the single-sided / double-sided setting area, since blank paper cleaning is only for single-sided paper passing, the “single-sided → single-sided” mode is displayed (white), and the other button portions cannot be selected.

  In the paper selection setting area D7, only selectable paper buttons are outlined. Here, as an example, the A4 vertical plain paper button and the B4 vertical plain paper button are displayed as selectable, and the A4 horizontal thin paper button has a thickness that the thin paper stored in the paper tray is not suitable for white paper cleaning. Therefore, this is an example in which selection is not possible.

  Such selectable / unselectable display control is performed automatically by the control means having a predetermined reference, and comparing the reference with the data of the type of paper stored in the paper tray. Is called.

  One of the predetermined criteria is the type of paper used in the job performed before the jam occurred. For example, when an A4 portrait paper has been used in the previous job, a paper size of A4 portrait or larger must be selected. Also, label paper and paper such as OHP that are not suitable for blank paper cleaning should not be selectable.

  When the user selection in FIG. 8, FIG. 9, and FIG. 10 is completed, the process proceeds to step S12 of this routine, and it is determined whether or not blank paper cleaning is to be performed, the process proceeds to step S13.

  In step S13, it is determined whether or not blank paper cleaning has been selected for the first fixing device 20a. If YES, it is determined in step S14 whether or not the temperature of the first fixing device 20a has reached the blank paper cleaning permission temperature of 180 ° C. or higher. Make a decision.

  If YES in step S14, the blank sheet cleaning permission flag Fa1 for the first fixing device 20a is set (step S15). If NO, the blank sheet cleaning permission flag Fa1 is cleared (step S16).

  Similarly, it is determined in step S17 whether or not blank paper cleaning has been selected for the second fixing device 20b. If YES, the temperature of the second fixing device 20b becomes equal to or higher than the blank paper cleaning permission temperature of 165 ° C. in step S18. Judge whether or not. If YES in step S18, the blank sheet cleaning permission flag Fa2 for the second fixing device 20b is set (step S19). If NO, the blank sheet cleaning permission flag Fa2 is cleared (step S20).

  In step S21, the process waits for both of the blank paper cleaning permission flags Fa1 and Fa2 to be set to the first and second fixing devices to proceed to step S22, and starts blank paper passing.

  The state in which both the blank paper cleaning permission flags Fa1 and Fa2 are set in step S21 means that when the sheet stays in the first fixing device 20a, the temperature of the first fixing device 20a becomes the control temperature of 180 ° C. or higher. In the case where the sheet stays in the second fixing device 20b, the temperature of the second fixing device 20b is equal to or higher than the control temperature 165 ° C. At this time, blank paper cleaning is executed even if the temperature of the other fixing device does not reach the control temperature.

  When blank paper cleaning is started in step S22, it is determined in step S23 which fixing device is selected in FIG. 9, and if the second fixing device 20b is selected, the second fixing device 20b is informed. It is determined whether to pass the sheet (step S24) or not (step S25), and the flowchart is ended. In accordance with the determinations in steps S24 and S25, the control unit CU controls the conveyance path switching member to perform direct discharge or bypass discharge.

  As described above, according to the present invention, if there is a possibility that the paper has accumulated in the fixing device, whether or not to perform blank paper cleaning for the user on the display selection screen on the operation panel, to which fixing device the white paper cleaning is performed. Since it is configured to check and select the number of papers to be used and the number and type of paper used for blank paper cleaning, unnecessary blank paper cleaning is not necessary, Since it can be performed using the paper path, the number of sheets, and the type of paper, it is efficient and economical.

  In the above-described embodiment of the present invention, the fixing device of the two-row serial arrangement has been described, but it is obvious that the fixing device of the three-row serial arrangement can be applied. Further, the present invention is not limited to the serial arrangement, and can be applied to a configuration in which a plurality of fixing devices are arranged in parallel and each fixing device is selectively used. Further, the fixing device is not limited to the belt fixing method and can be applied to a heat roller method.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 2Y Yellow image forming unit 2M Magenta image forming unit 2C Cyan image forming unit 2K Black image forming unit 10 Paper feeding device 20a First fixing device 20b Second fixing device 21a, 21b Fixing belt 22a, 22b Pressure roller 23a , 23b Support rollers 24a, 24b Heating rollers 30, 31, 32, 33 Transport path switching member Ra First transport path Rb Second transport path Rc Straight transport path Rd Bypass transport path Re Straight transport path Rf Bypass transport path Rg Bypass discharge path Rh bypass reversing path Ri reversing path Rj bypass conveying path Rk double-sided conveying path CU control means SP operation panel SS paper sensor TC1 first fixing temperature adjusting circuit TC2 second fixing temperature adjusting circuit

Claims (11)

A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Whether to execute the blank cleaning possess a selection means for selecting a user, the after jam processing,
The image forming system according to claim 1, wherein the selection unit displays a display selection screen for selectively displaying whether or not to perform blank paper cleaning for each fixing device . A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Selection means for allowing the user to select whether or not to perform blank paper cleaning after the jam processing,
The image forming system according to claim 1, wherein the selection unit displays, as a default, a display indicating that blank paper cleaning is to be performed on a fixing device in which paper may have accumulated. A plurality of fixing devices arranged in a paper conveyance path downstream of the image forming means;
A paper stay determining means for determining whether or not there is a possibility that the paper stays in the nip portion of each fixing device when a jam occurs;
A blank sheet cleaning control means for performing blank sheet cleaning for passing through the sheet and cleaning the fixing apparatus with respect to the fixing apparatus that has been determined that the sheet may have accumulated at the time of restart after the jam processing;
Selection means for allowing the user to select whether or not to perform blank paper cleaning after the jam processing,
The selection unit displays a sheet number display screen for displaying the number of sheets to be passed when performing blank sheet cleaning, and displays the number of sheets depending on whether the number of fixing devices in which the sheet may stay is one or more. An image forming system that controls to change a default number of sheets to be displayed on a screen. Said selecting means, an image forming system according to claim 2 or 3, wherein the displaying the display selection screen for whether alternative display performs blank cleaning for each fixing device. It said selecting means, an image forming system according to claim 1 or 3, characterized in that the default display an indication to perform a blank cleaning the fixing device that may paper is retained. The selection unit displays a sheet number display screen for displaying the number of sheets to be passed when performing blank sheet cleaning, and displays the number of sheets depending on whether the number of fixing devices in which the sheet may stay is one or more. 3. The image forming system according to claim 1, wherein control is performed to change a default number of sheets to be displayed on the screen. It said selecting means, when it is determined that the sheet staying determination means that there is a possibility that the sheet is retained in one of the fixing device even without low, and displaying whether to execute the white paper cleaning The image forming system according to claim 1. 2. The control unit according to claim 1, wherein the selection unit displays a paper setting screen that displays a paper type, and controls to select a paper type that can be used for blank paper cleaning from the paper setting screen. 7 the image forming system according to any one of. 9. The image forming system according to claim 8 , wherein the selection unit displays the sheet type to be displayed in a selectable manner with reference to the sheet type used in the job before the jam occurrence. It said selecting means, an image forming system according to any one of claims 1 9, characterized in that it comprises a display selection screen including a touch panel. The image forming system according to any one of claims 1 to 10 , wherein the blank paper cleaning control unit allows a sheet used for cleaning to pass through without forming an image by the image forming unit.

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