JP2013164616A - Image forming apparatus and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer prevented from wasting a sheet by completing all printing also to a rear surface of the sheet where one surface was already printed and is waiting in a double-sided unit even when paper-out occurs in double-sided printing sequence.SOLUTION: When an engine control section 203 receives a paper-out detection signal due to a state where sheets in a cassette is exhausted, if the sheet where a front surface was printed is waiting in the double-sided unit, a "/TOP" signal for the rear surface of the sheet is outputted. Then, a controller section 201 is informed of occurrence of misprinting caused by the paper-out. When completing image formation of a rear surface side of the sheet, and completing conveyance of the sheet to an outside of an image forming apparatus after the sheet passes through a fixed and ejected paper sensor 20, a sheet conveying condition status is set to a non-conveying condition to perform misprinting releasing sequence.

Description

  The present invention relates to an image forming apparatus applicable to an image forming apparatus such as an electrophotographic system, an electrostatic storage system copying machine, and a printer, and a control method therefor.

  With reference to FIG. 1, an outline of the overall configuration of a laser printer as an image forming apparatus will be described.

  As shown in FIG. 1, a laser printer forms an electrostatic latent image in an image forming unit using image light formed based on an image signal transmitted from a controller unit (not shown), and develops the electrostatic latent image. A color visible image is formed by superimposing and transferring the visible image. This color visible image is transferred to a sheet (that is, a recording material) 2 and the color visible image on the sheet 2 is fixed. The image forming unit includes a photoconductor (5Y, 5M, 5C, 5K) for each station arranged side by side for development colors (four colors), an injection charging unit (7Y, 7M, 7C, 7K) as a primary charging unit, a developing unit ( 8Y, 8M, 8C, 8K). The image forming unit further includes a toner cartridge (11Y, 11M, 11C, 11K), an intermediate transfer body 12, a paper feeding unit 1, a transfer unit, and a fixing unit 11. Here, Y represents the development color yellow, M represents the development color magenta, C represents the development color cyan, and K represents the development color black.

  The photoreceptor (5Y, 5M, 5C, 5K), the injection charging means (7Y, 7M, 7C, 7K) as the primary charging means, and the developing means (8Y, 8M, 8C, 8K) can be attached to and detached from the main body of the image forming apparatus. Are mounted on various process cartridges (22Y, 22M, 22C, 22K).

  The photosensitive drums (photoconductors) 5Y, 5M, 5C, and 5K are configured by applying an organic optical transmission layer to the outer periphery of an aluminum cylinder, and are rotated by the driving force of a driving motor (not shown) being transmitted. The drive motor rotates the photosensitive drums 5Y, 5M, 5C, and 5K in the counterclockwise direction according to the image forming operation. Exposure light to the photosensitive drums 5Y, 5M, 5C, and 5K is sent from the scanner units 10Y, 10M, 10C, and 10K, and is selectively exposed on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K, so An image is formed.

  The primary charging means includes four injection chargers 7Y, 7M, 7C, and 7K for charging yellow (Y), magenta (M), cyan (C), and black (K) photoconductors for each station. I have. Each injection charger is provided with sleeves 7YS, 7MS, 7CS, and 7KS.

  In order to visualize the electrostatic latent image, the developing unit includes four developing units 8Y and 8M that develop yellow (Y), magenta (M), cyan (C), and black (K) for each station. , 8C, 8K. Each developing device is provided with sleeves 8YS, 8MS, 8CS, and 8CK. Each developing device is detachably attached.

  The intermediate transfer body 12 is in contact with the photosensitive drums 5Y, 5M, 5C, and 5K, rotates clockwise when forming a color image, rotates with the rotation of the photosensitive drums 5Y, 5M, 5C, and 5K, and is visible. Receive image transfer. Further, the intermediate transfer body 12 simultaneously superimposes and transfers the color visible image on the intermediate transfer body 12 onto the paper 2 by nipping and conveying the paper 2 by contact with a transfer roller 9 described later at the time of image formation.

  While the color visible image on the intermediate transfer body 12 is superimposed and transferred onto the paper, the transfer roller 9 is positioned at 9a and brought into contact with the intermediate transfer body, but at the end of the printing process, the transfer roller 9 is positioned at 9b. Separate.

  In other words, the transfer roller 9 moves in the direction of the arrow in the drawing and makes contact with and separation from the intermediate transfer body 12.

  The fixing unit 13 fixes the transferred color visible image while conveying the paper 2, and includes a fixing roller 14 that heats the paper 2 and a pressure roller 15 that presses the paper 2 against the fixing roller 14. It has. The fixing roller 14 and the pressure roller 15 are formed in a hollow shape, and heaters 16 and 17 are incorporated therein. That is, the sheet 2 holding the color visible image is conveyed by the fixing roller 14 and the pressure roller 15, and the toner is fixed on the surface by applying heat and pressure. The sheet 2 after fixing the visible image is discharged to the paper discharge unit, and the image forming operation is completed.

  The printer includes a lower transport sensor A 23, an upper transport sensor A 24, a lower transport sensor B 25, an upper transport sensor B 26, a registration sensor 19, a pre-fixing sensor 27, a fixing paper discharge sensor 20, and a paper discharge sensor 28 on the paper transport path. To manage the conveyance status of the paper. Further, a sensor (not shown) for detecting the presence or absence of paper in the paper feed unit 1 is provided at the paper feed port of the paper feed unit (cassette) 1.

  The cleaning unit 21 cleans the toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K and the intermediate transfer body 12. By this cleaning, the waste toner after transferring the visible image formed by the toner formed on the photosensitive drums 5Y, 5M, 5C, and 5K to the intermediate transfer body 12 is stored in the cleaner container. Further, the waste toner after transferring the four color visible images formed on the intermediate transfer member 9 to the paper 2 by this cleaning is stored in a cleaner container.

  FIG. 2 is a block diagram for explaining the system configuration of the image forming apparatus. The controller unit 201 can communicate with the host computer 200 and the engine control unit 203. The controller unit 201 receives image information and a print command from the host computer 200. The controller unit 201 analyzes the received image information and converts it into bit data, and sends a print reservation command, a print start command, and a video signal to the engine control unit 203 via the video interface unit 210 for each sheet. .

  The engine control unit 203 has a CPU 211 for receiving commands and data transmitted from the controller 201 via the video interface unit 210 and instructing operation processing for image formation. The engine control unit 203 further includes an image processing unit 212 as a circuit for processing image data for printing, and an image control unit 213 that performs read control of data processed by the image processing unit. The engine control unit 203 further includes a fixing control unit 214 that controls the fixing temperature of the fixing unit 13 and the like, a paper transport unit 215 for transporting the paper transported into the image forming apparatus (a plurality of transport roller pairs in FIG. 1). Equivalent). The engine control unit 203 further includes a drive control unit 216 that controls driving of a motor (not shown) for driving the paper transport unit 215, double-side control that controls detection of a paper transport state and transport operation in the duplex unit. Part 217. Further, the CPU 211 controls each part constituting the engine according to a control procedure (including a control procedure shown in FIG. 3) in a ROM (not shown).

  The controller unit 201 transmits a print reservation command to the engine control unit 203 in accordance with a print command from the host computer 200, and transmits a print start command to the engine control unit 203 at a timing when printing is possible. At this time, based on an instruction from the host computer 200, the controller unit 201 instructs the paper discharge option control unit 202 to use the paper discharge control option, and further supplies the paper feed option control unit 204 with a paper feed control option. Also sends instructions for use.

  The engine control unit 203 prepares for execution of printing in the order of print reservation commands from the controller unit 201 and waits for a print start command from the controller unit 201. When the engine control unit 203 receives the print instruction, the engine control unit 203 outputs a / TOP signal serving as a reference timing of the video signal output to the controller unit 201, and starts a printing operation in accordance with a print reservation command. In addition, the engine control unit 203 outputs a / TOPR signal that is a timing at which the sheet waiting on the registration roller is re-fed. When the / TOPR signal becomes “true”, the controller unit 201 issues a refeed instruction to the sheet feed option input device via the sheet feed option control unit 204.

  FIG. 3 is a flowchart of the printing operation of the engine control unit 203. Upon receiving the print reservation command, the engine control unit 203 waits for the reception of the print start command (501), and executes preprocessing (hereinafter referred to as “pre-rotation sequence”) for performing the print operation (502). After completion of the pre-rotation sequence, the / TOP signal is output and the printing operation is started in accordance with the print reservation command for the first sheet (503). If the next print reservation command has not been received by the next print operation start timing (hereinafter referred to as “normal print start timing”) for maintaining the throughput (505), the engine control unit 203 proceeds to step 509. move on. In step 509, post-processing of the printing operation (hereinafter referred to as “post-rotation sequence”) is executed, and the printing operation is terminated. If a print reservation command is received by the next normal print start timing and if a print start command for that print reservation command is received, the second print will be printed following the first print. The operation is started (506, 503). If the print reservation command has been received before the next normal print start timing and if the print start command has not been received, the post-rotation sequence is executed and the print start command is waited (507, 508) Waiting for reception of a print start command. When the print start command is received, the pre-rotation sequence is started (502).

  FIG. 4 shows a communication sequence from feeding of the sheet feeding unit 1 and feeding of the duplex unit alternately until starting duplex printing of four sheets. The controller unit 201 transmits to the engine control unit 203 a reservation command for supplying paper from the paper supply unit 1 and discharging it to the duplex unit at 311 with reservation ID = 1, and from 312 for paper supply from the paper supply unit 1. Then, a reservation command for discharging the sheet to the duplex unit is transmitted with reservation ID = 2. In 313, a reservation command for feeding from the duplex unit and discharging it to the paper discharge unit outside the machine is transmitted with reservation ID = 1. These operations are similarly repeated for the remaining reservation IDs (314, 315, 316, 317, 318). Next, the controller unit 201 starts printing the ID reserved by the reservation command in 319 to the engine control unit 203, and the engine starts a printing operation. The engine control unit 203 outputs an image forming sequence after receiving a print start command, outputs a / TOP signal and a / TOPR signal to the controller unit 201 (320, 321), and forms an image. On the other hand, the controller unit 201 outputs a video signal in synchronization with the / TOP signal, and outputs a print start command for the next reservation ID. Note that, as indicated by the reservation commands 311 to 318, waiting one sheet for the duplex unit and alternately feeding paper from the sheet feeding unit 1 and the duplex unit is hereinafter referred to as two-sided duplex.

  FIG. 5 shows an image formation sequence when image formation is performed in accordance with the duplex printing communication sequence in FIG. In the following description, in double-sided printing, the first surface to be printed on one sheet that is fed from a cassette and discharged to the duplex unit is expressed as a front surface, and the image forming apparatus is fed from the duplex unit. The surface printed when discharged outside the machine is expressed as the back side. When the engine control unit 203 receives a print start command (print ID = 1) in response to a print reservation command on the first sheet, it starts a pre-rotation sequence. After completion of the pre-rotation sequence, the engine control unit 203 outputs a / TOP signal (100-1-S) to start the first sheet printing operation, and conveys the sheet from the cassette to the duplex unit (101-1- S). The controller unit 201 outputs video data to the engine control 203 in synchronization with the / TOP signal and starts image formation. The engine control unit 203 adjusts the timing between the sheet fed from the cassette by the registration sensor 19 and the image transferred to the intermediate transfer member by the image forming unit. The engine control unit 203 outputs a / TOPR signal by adjusting the timing, refeeds the paper, and transfers the image onto the paper (102-1-S). The image transferred onto the sheet is heated and fixed by the fixing unit 13, passes through the fixing sheet discharge sensor 20, and the image formation on the first sheet is completed (103-1-S). Similarly, when a print start command (print ID = 2) in response to a print reservation command for the second sheet surface is received, a / TOP signal (100-2-S) is output to start a print operation for the second sheet surface. That is, the sheet is conveyed from the cassette to the duplex unit (101-2-S), and the / TOPR signal is output (102-2-S). Next, the image on which the transfer of the image onto the paper has been completed is heat-fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the second sheet is finished (103-2 -S). Next, when a print start command (print ID = 1) in response to a print reservation command for the first sheet is received, a / TOP signal (100-1-D) is output and a printing operation for the first sheet is started. That is, the sheet is conveyed from the duplex unit (101-1-D) and the / TOPR signal is output (102-1-D). Next, the image on which the transfer of the image onto the paper has been completed is heated and fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the first back surface is completed (103-1 -D). The paper on which image formation has been completed on both the front and back surfaces passes through the paper discharge sensor 28 and is discharged out of the image forming apparatus. The above operation is repeated for four sheets. When all the image formation is completed, the post-rotation sequence is executed, and the print start command is waited again.

  6 alternately performs the paper feeding from the paper feeding unit 1 and the paper feeding from the duplex unit shown in FIG. 4, and executes the image forming sequence described in FIG. 5 according to the communication sequence until the start of four-sided printing on four sheets. An image forming sequence when the fourth sheet is out of paper in the paper feeding unit 1 is shown. In this case, printing cannot be continued. At this time, although the / TOP signal (100-4-S) on the front surface of the fourth sheet is output and image formation on the back surface of the first sheet is continued, the fourth sheet is out. For this reason, the sheet cannot be conveyed from the cassette to the duplex unit (101-4-S). When the paper in the cassette runs out, the paper feed port sensor of the paper feed unit 1 detects the absence of paper and notifies the engine control unit 203, so the engine control unit 203 sets the paper presence / absence status to the paper out status. . In addition, since the engine control unit 203 is in a paper-out state, it notifies the controller unit 201 that a misprint has occurred due to the absence of paper (110). When the engine control unit 203 is out of paper, the image forming operation up to the back side of the second sheet is continued. That is, the controller unit indicates that the sheet conveyance is stopped due to the sheet conveyance state status when the back side of the second sheet passes through the fixing sheet discharge sensor 20 and is discharged out of the image forming apparatus (103-2-D). 201 is notified.

  When a misprint occurs in the engine, the controller unit 201 determines a print ID necessary for recovery (reprinting) as follows when the paper conveyance status of the engine becomes non-conveyance. That is, the reservation ID that has already been registered, the ID that has been fed from the paper feed unit, and the ID that has already started printing are received from the engine control unit, and the print ID required for recovery (reprinting) is obtained. decide. In the example of FIG. 6, as shown in FIG. 7, it is determined that it is necessary to retransmit the third and fourth sheets from the reservation ID, the paper feeding ID, and the printing ID for the print ID. The engine control unit 203 executes a misprint cancel sequence in response to a misprint cancel command from the controller unit 201.

  A configuration for controlling the image forming operation by assigning an ID in this way is described in, for example, Japanese Patent Application Laid-Open No. H10-228707.

JP 2001-088496 A

  In the conventional example described above, when the absence of paper is detected, a misprint due to the absence of paper is notified to the controller unit 201, and image formation on the front and back sides of the print ID corresponding to the / TOP signal output up to that point is completed. At this point, the image forming operation is terminated. Then, the engine control unit 203 sets the sheet conveyance state status to “non-conveyance” and waits for misprint cancellation from the controller unit 201. At this time, since the single-side printed residual paper is present in the duplex unit, it is necessary to discharge the single-side printed residual paper in the image forming apparatus after canceling the misprint. The print ID for this single-sided printed paper is also a recovery target.

  In the example of FIG. 6, since the fourth sheet is misprinted without paper, when the second back surface image formation, which is the print ID before the first side (front side) of the fourth sheet, is completed, Set the paper transport status to non-transport. At this time, since the third sheet that has been printed on one side remains in the duplex unit, the third sheet is to be discharged outside the apparatus with only one side printed. Therefore, the controller unit 201 transmits the reservation command again for the third sheet that has not been determined to be out of paper and has been printed on one side once, and performs paper feeding and single-side printing again. I had to recover to do it.

  In other words, since the third sheet is discharged outside the state where both sides are not printed, the third sheet that has been printed on one side is wasted.

  The present invention has been made in view of the above problems, and an object thereof is to provide an improved image forming apparatus and a control method therefor.

  Another object of the present invention is to provide an image forming apparatus and a control method therefor that do not waste one-side printed paper remaining in the apparatus even when image formation cannot be continued during double-sided image formation. Is to provide.

  The present invention is an image forming apparatus, and includes an image forming unit for forming an image on a transfer member, a transfer unit for transferring an image formed on the transfer member to a recording material, and the recording material. A recording material storage unit for supplying the recording material, a supply unit for supplying the recording material from the recording material storage unit to the transfer unit, and a recording material detection unit for detecting the absence of the recording material in the recording material storage unit; A controller for controlling the recording material conveyance operation, and the control unit is configured to detect the inside of the recording material container by the recording material detection unit during an image forming operation on both surfaces of the recording materials. When it is detected that there is no recording material, an image is formed on the first surface that is being transported in the apparatus after executing a control operation for forming an image on the recording material that is not supplied by the supply unit. After transferring the image to the second surface of the formed recording material Wherein the stopping the image forming operation.

  In addition, the present invention is a method for controlling an image forming apparatus, in which, during an image forming operation on both surfaces of a plurality of recording materials, it is detected that there is no recording material supplied for the image formation. In addition, after the first step of performing a control operation when image formation is performed on a recording material that is not supplied, and after the first step, the image is formed on the first surface while being transported in the apparatus. And a second step of forming an image on the second surface of the recording material.

  Furthermore, the present invention is an image forming apparatus, an image forming unit for forming an image on a transfer body, a transfer unit for transferring an image formed on the transfer body to a recording material, and the recording material A recording material storage unit for storing the recording material, a supply unit for supplying the recording material from the recording material storage unit to the transfer unit, a detection unit for detecting a supply state of the recording material supplied by the supply unit, A control unit that controls the conveyance operation of the recording material, and the control unit is in a state in which the recording material is not supplied by the detection unit during an image forming operation on both surfaces of the plurality of recording materials. In the case of detection, after executing a control operation when image formation is performed on the recording material not supplied by the supply unit, the second recording material on which the image is formed on the first surface being conveyed in the apparatus Transfer the image to the surface, and then stop the image forming operation. Characterized in that to.

  Furthermore, the present invention provides a method for controlling an image forming apparatus, wherein a state in which a recording material supplied for image formation is not supplied is detected during an image forming operation on both surfaces of a plurality of the recording materials. In this case, a first step of performing a control operation when image formation is performed on a recording material that is not supplied, and after the first step, the image is being formed on the first surface while being transported in the apparatus. And a second step of forming an image on the second surface of the recorded material.

  According to the present invention, there is provided an image forming apparatus that does not waste one-side printed paper remaining in the machine and a control method thereof even when image formation cannot be continued during double-sided image formation. Can do.

1 is a diagram illustrating a schematic configuration of an image forming apparatus. 1 is a diagram illustrating an outline of a control system of an image forming apparatus. 5 is a flowchart of an image forming sequence performed by the image forming apparatus. It is a figure which shows the flow of a double-sided print command. It is a figure which shows four sheets of alternate double-sided image formation sequences (when normal). It is a figure which shows the case where the absence of paper is detected at the time of two sheet double-sided image formation of a prior art example. It is a figure which shows the engine status at the time of misprinting by the absence of paper at the time of four alternating double-sided image formation of a prior art example. FIG. 6 is a diagram illustrating a case where no paper is detected when four alternating double-sided images are formed according to the first exemplary embodiment. FIG. 6 is a diagram illustrating an engine status at the time of misprinting due to the occurrence of paper out when four alternating double-sided images are formed according to the first exemplary embodiment. FIG. 6 is a diagram illustrating a case where no paper is detected when five double-sided images are formed according to the second exemplary embodiment. FIG. 10 is a diagram illustrating an engine status at the time of misprinting due to the absence of paper when five alternating double-sided images are formed according to the second exemplary embodiment. FIG. 10 is a flowchart for explaining processing at the time of misprinting due to the absence of paper when N double-sided alternating images are formed in Embodiment 3. FIG.

Embodiments to which the present invention can be applied will be described below in detail with reference to the drawings.
Example 1
In this embodiment, even when a paper-out condition occurs during the two-sided alternating double-sided sequence, all the images on the back side of the paper that has already finished the image formation on one side and is waiting in the image forming apparatus are formed. The point is that it is completed. In other words, a method is proposed in which a single-side printed sheet in a duplex unit is printed normally and discharged outside the machine without wasting it. Here, the two-sheet alternate double-sided sequence is a state in which a single-side recorded sheet is kept waiting in the duplex unit, and image formation is performed while alternately feeding from the sheet feeding unit 1 and the duplex unit. Control. Since the configuration and basic operation of the image forming apparatus already described are the same as those described above, detailed description thereof is omitted, and the same reference numerals are given to the diagrams.

  In this embodiment, the CPU 211 configuring the engine control unit 203 performs control according to a control procedure based on a program in a ROM (not shown). Specifically, the CPU 211 refers to the output of each of the sensors 23 to 28, and regarding the job currently being processed, where the paper is in the conveyance path, that is, the image is formed on the front side or the back side of the paper. It is determined whether or not it has been made. Further, the CPU 211 grasps the number of sheets counted from the first sheet on which the image is formed. In the engine control unit 203, the CPU 211 controls the operation of each component of the printer engine according to a control procedure (including a control procedure of FIG. 12 described later) based on a program in a ROM (not shown).

  FIG. 8 shows a case where the fourth sheet runs out of the paper in the paper feeding unit 1 and the printing cannot be continued during the execution of the image forming sequence explained in FIG. 5 according to the two-sheet alternate duplex communication sequence explained in FIG. It is an image formation sequence. When the engine control unit 203 receives a print start command (print ID = 1) in response to a print reservation command on the first sheet, it starts a pre-rotation sequence. After completion of the pre-rotation sequence, the engine control unit 203 outputs a / TOP signal (100-1-S) as a timing signal that is a timing for outputting video data to the image forming unit. As a result, the printing operation for the first sheet is started, and the sheet is conveyed from the cassette to the duplex unit (101-1-S). The controller unit 201 outputs video data to the engine control unit 203 in synchronization with the / TOP signal and starts image formation. The engine control unit 203 adjusts the timing between the sheet fed from the cassette by the registration sensor 19 and the image transferred to the intermediate transfer member by the image forming unit. The engine control unit 203 outputs a / TOPR signal by adjusting the timing, refeeds the paper, and transfers the image onto the paper (102-1-S). The image transferred onto the sheet is heated and fixed by the fixing unit 13, passes through the fixing sheet discharge sensor 20, and the image formation on the first sheet is completed (103-1-S). Similarly, when a print start command (print ID = 2) in response to a print reservation command for the second sheet surface is received, a / TOP signal (100-2-S) is output to start a print operation for the second sheet surface. That is, the sheet is conveyed from the cassette to the duplex unit (101-2-S), and the / TOPR signal is output (102-2-S). Next, the image on which the transfer of the image onto the paper has been completed is heat-fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the second sheet is finished (103-2 -S). Next, when a print start command (print ID = 1) in response to a print reservation command for the first sheet is received, a / TOP signal (100-1-D) is output and a printing operation for the first sheet is started. That is, the sheet is conveyed from the duplex unit (101-1-D) and the / TOPR signal is output (102-1-D). Next, the image on which the transfer of the image onto the paper has been completed is heated and fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the back surface of the first sheet is completed (103-1 -D). The first sheet on which image formation has been completed on both the front and back sides passes through the paper discharge sensor 28 and is discharged out of the image forming apparatus.

  While the above operations are being performed for the double-sided recording operation for four sheets, the / TOP signal (100-4-S) on the front surface of the fourth sheet is output and image formation on the back surface of the first sheet is continued. The second sheet is out of paper. Therefore, the fourth sheet cannot be fed and conveyed from the cassette (101-4-S). When there is no more paper in the cassette, the engine control unit 203 receives the paper absence detection signal from the paper feed port sensor of the paper feeding unit 1 and sets the paper presence / absence status to the paper absence state (150).

  At this time, the engine control unit 203 outputs the / TOP signal on the back side of the third sheet because the third sheet that has been printed on one side is waiting in the duplex unit even after it is determined that there is no paper. (100-3-D). After outputting the / TOP signal for the third back image, the engine control unit 203 notifies the controller unit 201 that a misprint has occurred due to the absence of paper (151).

  Further, the engine control unit 203 detects that the fourth sheet has run out of paper. However, for the fourth sheet that has already output the / TOP signal in 100-4-S, the engine control unit 203 uses the / TOPR to guarantee the consistency of the timing of the image forming operation to the controller unit 201. A signal is output (102-4-S).

  When the image formation on the front and back surfaces of the third sheet has been completed and the conveyance of the image forming apparatus to the outside of the image forming apparatus has been completed, the engine control unit 203 sets the sheet conveyance status to non-display. Set during transportation (152).

  In this embodiment, even when it is detected that the fourth sheet has run out, based on the print ID information, the / TOP signal for the third back image is output to transfer the third back image to the intermediate transfer member. 12 to form. Then, in order to adjust the timing of image formation, that is, the timing of transferring the image from the intermediate transfer body 12 to the paper, the / TOPR signal for transferring the image on the fourth sheet surface is output. After that, the / TOPR signal for the image on the back side of the third sheet is output next, and the third back side image formed on the intermediate transfer body 12 is transferred to the sheet.

  That is, for the image on the front surface of the fourth sheet, in order to properly transfer the image on the intermediate transfer body to the back surface of the third sheet while maintaining the order of image formation by the four-sided double-sided image forming operation, Outputs the / TOPR signal for the image on the front side of the sheet. Next, the / TOPR signal of the image on the back of the third sheet is output.

  Here, the image on the front surface of the fourth sheet is formed before the back image of the third sheet in a normal state where no paper is generated. 12 is not formed. Specifically, the engine control unit 203 executes the following control. That is, the image data is transmitted from the controller unit 201 to the engine control unit 203 based on the / TOP signal, but the scanner units (10Y, 10M) are not formed on the photosensitive drums (5Y, 5M, 5C, 5K). 10C, 10K) is prohibited.

  Thereafter, the engine control unit 203 controls the image forming operation to be stopped after the image is transferred to the back surface of the third sheet re-feeded from the duplex unit and discharged outside the apparatus. Note that the image on the surface of the fourth sheet may be formed without prohibiting the light emission of the scanner unit as described above. However, in that case, the transfer roller 9 may be positioned at 9b (separated state) to pass through the transfer portion (nip portion between the intermediate transfer member and the transfer roller) and then cleaned by the cleaning means 21.

  When a misprint due to the absence of paper occurs in the engine, the controller unit 201 determines a print ID necessary for recovery when the paper conveyance status of the engine becomes non-conveyance. In other words, the reservation ID that has already been registered, the ID that has been fed from the paper feed unit, and the ID that has already started printing are received from the engine control unit 203 to determine the print ID required for recovery. In the example of FIG. 8, as shown in FIG. 9, it is determined that it is necessary to retransmit only the fourth sheet from the reservation ID, the feeding ID, and the printing ID with respect to the printing ID. The engine control unit 203 executes a misprint cancel sequence in response to a misprint cancel command from the controller unit 201. At this time, in the conventional example, the third sheet that has been printed on one side remains in the duplex unit as residual paper, and therefore, it is necessary to discharge the third residual sheet after canceling the misprint. The third sheet is a sheet that has been fed before it is determined that there is no sheet, and has already been printed on one side. In the conventional example, this single-sided printed ID is also a target of recovery, but in this example, the discharge is completed after the double-sided image is formed up to the third single-sided printed ID. That is, unnecessary paper discharge processing is not necessary. Further, since the number of sheets for recovery is reduced, there is no waste of paper.

  In this embodiment, a timing signal (/ TOPR signal) for the fourth front image that is out of paper is output to adjust the transfer timing of the third back image. As a result, in the image forming apparatus including the intermediate transfer member as in the present embodiment, it is possible to appropriately form an image on the back surface of the paper that has been printed on one side and remains in the apparatus, and then can be discharged.

(Example 2)
In this embodiment, even when a paper out condition occurs during the three-sided alternating double-sided sequence, all the images on the back side of the paper that has already finished the image formation on one side and is waiting in the image forming apparatus are formed. The point is that it is completed. In other words, a method is proposed for discharging normally printed paper out of the apparatus without wasting printed paper on one side in the duplex unit. Here, the three-sided alternating double-sided sequence executes image formation while alternately feeding paper from the paper feeding unit 1 and the double-sided unit in a state where two single-sided recorded papers are kept waiting for the double-sided unit. Control. Since the configuration and basic operation of the image forming apparatus are the same as those described above, detailed description thereof is omitted, and the same reference numerals are given to the diagrams.

  FIG. 10 shows an image forming sequence in the case where the fourth sheet runs out of paper in the sheet feeding unit 1 during the double-sided image formation of five sheets, and printing cannot be continued. When the engine control unit 203 receives a print start command (print ID = 1) in response to a print reservation command on the first sheet, it starts a pre-rotation sequence. After completion of the pre-rotation sequence, the engine control unit 203 outputs a / TOP signal (200-1-S) to start the first printing operation, and conveys the sheet from the cassette to the duplex unit (201-1- S). The controller unit 201 outputs video data to the engine control 203 in synchronization with the / TOP signal and starts image formation. The engine control unit 203 adjusts the timing between the sheet fed from the cassette by the registration sensor 19 and the image transferred to the intermediate transfer member by the image forming unit. The engine control unit 203 adjusts the timing to output the / TOPR signal, refeed the paper, and transfer the image onto the paper (202-1-S). The image transferred onto the sheet is heated and fixed by the fixing unit 13, passes through the fixing sheet discharge sensor 20, and the image formation on the first sheet is completed (203-1-S). Similarly, when a print start command (print ID = 2) in response to a print reservation command for the second sheet surface is received, a / TOP signal (200-2-S) is output to start a print operation for the second sheet surface. That is, the sheet is transported from the cassette to the duplex unit (20-2-S), and the / TOPR signal is output (202-2-S). Next, the image on which the transfer of the image onto the paper has been completed is heat-fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the second sheet is finished (203-2 -S). In the case of three-sided alternating two-sided printing, when a print start command (print ID = 3) is received in response to a print reservation command for the third sheet surface, a / TOP signal (200-3-S) is output to print the second sheet surface. To start. That is, the sheet is conveyed from the cassette to the duplex unit (201-3-S), and the / TOPR signal is output (202-3-S). Next, the image on which the transfer of the image onto the paper has been completed is heated and fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation for the third sheet is finished (203-3 -S). Next, when a print start command (print ID = 1) is received in response to a print reservation command for the first sheet, the / TOP signal (200-1-D) is output to start the printing operation for the first sheet. That is, the sheet is conveyed from the duplex unit (201-1-D) and / TOPR output is performed (202-1-D). Next, the image on which the transfer of the image onto the paper has been completed is heated and fixed by the fixing unit 13, passes through the fixing paper discharge sensor 20, and the image formation on the first back surface is completed (203-1 -D). The first sheet on which image formation has been completed on both the front and back sides passes through the paper discharge sensor 28 and is discharged out of the image forming apparatus.

  While the above operations are being performed for the double-sided recording operation for five sheets, the / TOP signal (200-4-S) on the front surface of the fourth sheet is output to start image formation on the back surface of the first sheet. The second sheet is out of paper. Therefore, the fourth sheet cannot be transported from the cassette (201-4-S). When there is no more paper in the cassette, the engine control unit 203 receives the paper absence detection signal from the sensor of the paper feeding unit and sets the paper presence / absence status to the paper out state (250). At this time, even after it is determined that there is no paper, the engine control unit 203 waits for the second and third sheets that have been printed on one side in the duplex unit. The / TOP signal on the back surface of the third sheet is output (200-2-D, 200-3-D).

  After outputting the third back / TOP signal, the engine control unit 203 notifies the controller unit 201 that a misprint has occurred due to the absence of paper (251). Further, the engine control unit 203 outputs the / TOP signal (200-4-S, 200-5-S) although the fourth sheet is out of paper. For the fourth and fifth sheets that have output the / TOP signal, the / TOPR signal is output in order to ensure consistency with the controller unit 201 such as the timing of the image forming operation (202-4-S). 202-5-S).

  After the misprint notification, the engine control unit 203 outputs the / TOPR signal in the following order. That is, the / TOPR signal for the fourth front image, the / TOPR signal for the second back image, the / TOPR signal for the fifth front image, the / TOPR signal for the third back image in the order / TOPR Output a signal. When the image formation on the front and back surfaces of the second and third sheets is completed, and the sheet is passed through the fixing discharge sensor 20 and the conveyance of the image forming apparatus to the outside of the apparatus is completed, the sheet conveyance status is set to non-display. Set during transport (252).

  In this embodiment, even when it is detected that the fourth sheet has run out, the / TOP signal for the second back image and the / TOP signal for the third back image are generated based on the print ID information. Then, the second and third back images are formed on the intermediate transfer body 12.

  Then, the following signals are output in order to adjust the timing of image transfer, that is, the timing of transferring the image from the intermediate transfer body 12 to the paper while maintaining the order of the image forming operations of five sheets alternately on both sides. That is, the / TOPR signal for transferring the fourth surface image and the / TOPR signal for transferring the fifth surface image are output.

  As described above, the / TOPR signal for the fourth front image, the / TOPR signal for the second back image, the / TOPR signal for the fifth front image, the / TOPR signal for the third back image To output the / TOPR signal. As a result, the image can be transferred to the second and third back surfaces.

  In this way, the timing of image formation on the intermediate transfer member is adjusted by outputting the / TOPR signal, and the sheet on the intermediate transfer member is appropriately transferred at the timing when the single-side printed paper is re-fed and reaches the transfer position. The image is transferred.

  Here, the images on the front surface of the fourth sheet and the front surface of the fifth sheet are normally formed in front of the second back image and in front of the third back image. Since no paper is generated, it is not formed on the intermediate transfer body 12. Specifically, image data is transmitted from the controller unit 201 based on the / TOP signal, but the scanner units (10Y, 10M,...) Are not formed on the photosensitive drums (5Y, 5M, 5C, 5K). 10C, 10K) is prohibited.

  After that, the image forming operation is controlled to be stopped after the image is transferred to the back surface of the second and third sheets re-feeded from the duplex unit and discharged to the outside of the apparatus.

  The fourth surface image and the fifth surface image may not be formed as described above, but may be formed on the intermediate transfer member. In this case, the transfer roller is positioned at 9b (separated state), the transfer portion (nip portion between the intermediate transfer member and the transfer roller) is passed through so as not to be transferred to the recording material, and then the cleaning means 21 is used. You can clean with.

  When a misprint due to the absence of paper occurs in the engine, the controller unit 201 determines a print ID necessary for recovery when the paper conveyance status of the engine becomes non-conveyance. That is, the reservation ID that has already been registered, the ID that has been fed from the paper feed unit, and the ID that has already started printing are received from the engine control unit, and the print ID required for recovery is determined. In the example of FIG. 10, as shown in FIG. 11, it is determined that it is necessary to retransmit only the fourth and fifth sheets from the reservation ID, the feeding ID, and the printing ID with respect to the printing ID. The engine control unit 203 executes a misprint cancel sequence in response to a misprint cancel command from the controller unit 201. At this time, as in the conventional example, when the engine control unit 203 detects the absence of paper when the absence of paper is detected, the second and third sheets that have been printed on one side are in the machine in the duplex unit. It remains. For this reason, it is necessary to discharge the second and third remaining sheets that have been printed on one side after canceling the misprint. The second and third sheets that have been printed on one side are sheets that have already been fed before it is determined that there is no paper, and have already been printed on one side. In the conventional example, this single-sided printed ID is also subject to recovery. In the present embodiment, the discharge of the single-side printed paper is completed after the images are formed on both sides. That is, the sheet on which the image is formed on only one side does not remain, so that an extra paper discharge process is not necessary. In addition, paper that is recovered is reduced, so paper is not wasted.

  Further, in this embodiment, the timing signal (/ TOPR signal) for the fourth front image and the fifth front image, which is out of paper, is intentionally output to output the second back surface and the third back image. Adjust the transfer timing. As a result, in the image forming apparatus including the intermediate transfer member as in the present embodiment, it is possible to appropriately form an image on the back surface of the paper that has been printed on one side and remains in the apparatus, and then can be discharged.

(Example 3)
The first embodiment proposes a method of discharging normally printed paper out of the apparatus without wasting paper in the duplex unit when there is no paper in the two-sided alternating duplex sequence. Further, in the second embodiment, a method has been proposed for ejecting normally printed paper out of the apparatus without wasting paper in the duplex unit when paper runs out during a three-sheet alternate duplex sequence. In this embodiment, even when no paper is generated in the N-side alternating double-sided sequence, all the images on the back side of the paper already waiting for the image forming apparatus after one-sided image formation is completed are formed. Propose how to complete In other words, we propose a method for discharging normally printed paper out of the machine without wasting paper in the duplex unit when there is no paper when N sheets are alternately placed on both sides. Here, the N-sheet alternate double-sided sequence is a state where N-1 single-sided recorded sheets are kept waiting for the duplex unit, and image formation is performed while feeding from the sheet feeding unit 1 and the duplex unit alternately. Is the control to execute. Since the configuration and basic operation of the image forming apparatus are the same as those described above, detailed description thereof is omitted, and the same reference numerals are given to the diagrams.

  FIG. 12 shows the control from when the engine control unit 203 detects the absence of paper by the sensor of the paper feed port of the paper feed unit that is feeding paper, and notifies the controller unit 201 of the paper to be misprinted. Represents a flow. In the control flow, 150 in FIG. 8 corresponds to 701, 151 corresponds to 707 and 713, 152 corresponds to 717, and 250 in FIG. 10 corresponds to 701 in the second embodiment. 251 corresponds to 707 and 713, and 252 corresponds to 717.

  First, when the sensor of the paper feed unit detects that there is no paper to be fed (701), the engine control unit 203 notifies the controller unit 201 that there is no paper (702). . When there is no paper, the engine control unit 203 counts the number of sheets waiting in the duplex unit (703), and repeats the processing from 705 to 709 if there are sheets waiting in the duplex unit. . If there is no standby paper in the duplex unit, the processing from 711 to 715 is repeated.

  Processing from 711 to 715 will be described. In 711, the / TOP signal is output for the paper that has already been fed when the absence of paper is detected. Next, when all the / TOP signals of the fed paper are output (712), the controller unit 201 is notified that a misprint has occurred due to the absence of paper (713), and the flow proceeds to 714. If all the / TOP signals of the paper fed in 712 are not output, the process proceeds to 714. In 714, the / TOPR signal is output, and then in 715, the image is transferred onto the corresponding paper, heat-fixed, and the paper on which image formation has been completed on both the front side and the back side is discharged out of the machine. , Go to 716.

  Next, processing from 705 to 709 will be described. The processing from 705 to 709 is repeated until all sheets waiting in the duplex unit are discharged out of the image forming apparatus. In 705, when the / TOP signal is output at the / TOP signal output timing, and all the / TOP signals of the paper waiting in the duplex unit are output (706), a misprint due to the absence of paper has occurred in the controller unit 201. This is notified (707), and the process proceeds to 708. If all the / TOP signals of the paper waiting in the duplex unit are not output in 706, the process proceeds to 708. In 708, the / TOPR signal is output at the / TOPR signal output timing of the corresponding paper, and then in 709, the image is transferred onto the corresponding paper, heat-fixed, and image formation is completed on both the front side and the back side. In the case of the completed paper, it is discharged out of the apparatus, and the process proceeds to 716.

  After the processes from 705 to 709 and 711 to 715 are completed, it is confirmed that the paper being conveyed has been discharged out of the image forming apparatus (716). If all the sheets are not discharged outside the apparatus in 716, the process returns to 703. If all the sheets are discharged, in 717, the controller unit 201 is notified that there is no sheet being conveyed, and the process is terminated.

  By executing the above processing, even when there is no paper in the N-side alternating double-sided sequence, all of the back side of the paper that has already finished the image formation on one side and is waiting in the image forming apparatus. , Image formation can be completed. That is, it is possible not to waste the single-sided printed paper remaining in the duplex unit when there is no paper, and to discharge normally printed paper to the outside of the apparatus.

  In the present embodiment, as in the first and second embodiments, the / TOP signal and the / TOPR signal for the image on the surface of the paper that is not fed and is not fed are output, and the image is printed on the intermediate transfer member. Adjust the timing to form. As a result, in the image forming apparatus including the intermediate transfer member as in the present embodiment, it is possible to appropriately form an image on the back surface of the paper that has been printed on one side and remains in the apparatus, and then can be discharged.

  In the first, second, and third embodiments, the case where there is no paper during the alternate double-sided sequence has been described. However, the same sequence can be executed not only when there is no paper, but also when an error such as a delay of paper fed from the paper feed unit 1 or no paper feed occurs, for example. The delay of the fed paper or the poor feeding can be detected by whether or not the paper has reached the sensors A23 and A24 when a predetermined time has elapsed from the feeding start timing.

  The present invention is not limited to the above-described embodiments, but can include modifications of the same technical idea.

DESCRIPTION OF SYMBOLS 1 Paper feed part 2 Transfer material 5 Photoconductor 7 Charging means 8 Developing means 9 Transfer roller 10 Scanner part 12 Intermediate transfer body 11 Fixing part 19 Registration sensor 20 Fixing paper discharge sensor 28 Paper discharge sensor 200 Host computer 201 Controller 203 Engine control part

The present invention relates to an image forming apparatus, an image carrier, an intermediate transfer member on which an image formed on the image carrier is primarily transferred, and an image primarily transferred onto the intermediate transfer member. a transcription unit you secondarily transferred, the yield capacity means that to accommodate the serial Rokuzai, a supply means for supplying the recording material toward the front Kiten shooting means before KiOsamu volume unit, before KiOsamu volume comprising a detection unit you detect the recording material contained in the device, wherein the image bearing member and the to drive the intermediate transfer member, the first surface of the first recording material supplied by the supply means In the image forming apparatus for forming an image in the order of the first surface of the second recording material supplied by the supplying unit after the first recording material and the second surface of the first recording material, the supply after the unit has supplied the first recording medium, before if dangerous knowledge means does not detect said second recording medium, said intermediate rolling In a state of being continuously driven body, an image of a second surface of said image is formed on the first surface a first recording material was primarily transferred to the intermediate transfer member from the image bearing member is primarily transferred The image on the second surface of the first recording material is secondarily transferred to the first recording material.

The present invention is also an image forming apparatus , comprising an image carrier, an intermediate transfer member on which an image formed on the image carrier is primarily transferred, and an image primarily transferred onto the intermediate transfer member. a transfer unit that transfers the secondary to the recording material, and the yield capacity means that to accommodate the serial Rokuzai, before and supply means for supplying a recording material toward the front Kiten shooting means from KiOsamu volume means, by said supplying means after being fed, it comprises a detection means for detecting that the recording medium has reached a predetermined position in the transport direction upstream side of the transfer position where the image is secondarily transferred onto the recording material, and the said image bearing member drives the intermediate transfer member, the first surface of the first recording material supplied by the supply means, the first surface of the second recording material supplied by the supply means after said first recording medium, an image forming apparatus for forming an image in the order of the second surface of the first recording medium, the supply If after the stage has supplied the first recording medium, even after the lapse of a predetermined time after executing the operation for supplying the second recording medium, said detecting means does not detect said second recording medium, With the drive of the intermediate transfer member being continued , the image on the second surface of the first recording material on which the image is formed on the first surface is primarily transferred from the image carrier to the intermediate transfer member, The image on the second surface of the first recording material that has been primarily transferred is secondarily transferred to the first recording material.

Claims (8)

A primary transfer portion for transferring an image formed on the image carrier to an intermediate transfer member;
A secondary transfer portion for transferring an image primarily transferred onto the intermediate transfer member to a recording material;
A recording material accommodating portion for accommodating the recording material;
A supply unit for supplying the recording material from the recording material storage unit to the secondary transfer unit;
A recording material detection unit for detecting that the recording material is exhausted in the recording material storage unit;
A control unit for instructing start of image formation on the image carrier,
The first surface of the first recording material supplied by the supply unit, the first surface of the second recording material supplied by the supply unit after the first recording material, the first surface of the first recording material In the image forming apparatus for forming images in the order of the second surface, the second surface of the second recording material,
The control unit detects that there is no recording material in the recording material storage unit by the recording material detection unit during the operation of forming an image of the first surface of the first recording material, and supplies the recording material. Even if the second recording material is not supplied by the part, instructing the start of the formation of the image on the first surface of the second recording material not supplied by the supply part on the image carrier, By continuing the driving of the intermediate transfer member, the first image formation on the intermediate transfer member is started after the formation of the image of the first surface of the second recording material on the image carrier in response to the instruction. An image is formed on the first surface being conveyed through the apparatus after the intermediate transfer member has been moved for a predetermined period including a period until the primary transfer of the image on the first surface of the second recording material is completed. Transfer the image on the second surface of the first recording material from the image carrier to the intermediate transfer And primarily transferred to the image forming apparatus characterized by secondary transfer the images of the second surface of the transferred primary first recording medium to said first recording medium. A primary transfer portion for transferring an image formed on the image carrier to an intermediate transfer member;
A secondary transfer portion for transferring an image primarily transferred onto the intermediate transfer member to a recording material;
A recording material accommodating portion for accommodating the recording material;
A supply unit for supplying the recording material from the recording material storage unit to the secondary transfer unit;
A detection unit for detecting a supply state of the recording material supplied by the supply unit;
A control unit for instructing start of image formation on the image carrier,
The first surface of the first recording material supplied by the supply unit, the first surface of the second recording material supplied by the supply unit after the first recording material, the first surface of the first recording material In the image forming apparatus for forming images in the order of the second surface, the second surface of the second recording material,
Even when the control unit detects a state in which the second recording material is not supplied by the detection unit during an operation of forming an image of the first surface of the first recording material, Instructing the start of the formation of the image of the first surface of the second recording material not supplied by the supply unit on the image carrier and continuing the driving of the intermediate transfer member, thereby responding to the instruction From the start of image formation of the first surface of the second recording material to the image carrier to completion of primary transfer of the image of the first surface of the second recording material to the intermediate transfer member After the intermediate transfer member is moved for a predetermined period including a period, an image of the second surface of the first recording material on which the image is formed on the first surface being conveyed in the apparatus is transferred from the image carrier. The image on the second surface of the first recording material that has been primarily transferred to the intermediate transfer member and has been primarily transferred Image forming apparatus characterized by secondarily transferred serial first recording medium.   The first surface of the second recording material not supplied in response to an instruction to start forming the image of the first surface of the second recording material output from the control unit on the image carrier. The image forming apparatus according to claim 1, wherein the image is formed on the image carrier, and the formed image is primarily transferred to the intermediate transfer member. Furthermore, it has a cleaner for cleaning the intermediate transfer member,
The cleaner is secondarily transferred onto the intermediate transfer body after the image is secondarily transferred onto the second surface of the first recording material on which the image is formed on the first surface being conveyed in the apparatus. 4. The image forming apparatus according to claim 3, wherein an image on the first surface of the second recording material that is not cleaned is cleaned. In an image forming apparatus for transferring an image formed on an image bearing member to an intermediate transfer member and transferring the image primarily transferred onto the intermediate transfer member to a recording material, the first surface of the first recording material to be supplied The image is formed in the order of the first surface of the second recording material supplied after the first recording material, the second surface of the first recording material, and the second surface of the second recording material. An image forming apparatus control method comprising:
When it is detected that there is no recording material supplied to form an image during the operation of forming an image of the first surface of the first recording material, and the second recording material is not supplied Even in response to the instruction by instructing the start of the formation of the image on the first surface of the second recording material not supplied to the image carrier and continuing the driving of the intermediate transfer member. The primary transfer of the image on the first surface of the second recording material to the intermediate transfer member is completed after the formation of the image on the first surface of the second recording material on the image carrier is started. The image on the second surface of the first recording material on which the image has been formed on the first surface being conveyed through the apparatus after the intermediate transfer member has been moved for a predetermined period including the period until The image on the second surface of the first recording material that has been primary transferred from the body to the intermediate transfer body Control method characterized by secondarily transferred serial first recording medium. In an image forming apparatus for transferring an image formed on an image bearing member to an intermediate transfer member and transferring the image primarily transferred onto the intermediate transfer member to a recording material, the first surface of the first recording material to be supplied The image is formed in the order of the first surface of the second recording material supplied after the first recording material, the second surface of the first recording material, and the second surface of the second recording material. An image forming apparatus control method comprising:
Even when it is detected that the second recording material supplied for forming the image is not supplied during the operation of forming the image of the first surface of the first recording material, the supply is performed. Instructing the start of the formation of the image on the first surface of the second recording material on the image carrier, and continuing the driving of the intermediate transfer member, the image carrier is in accordance with the instruction. A predetermined period including a period from the start of image formation on the first surface of the second recording material to completion of primary transfer of the image on the first surface of the second recording material to the intermediate transfer member. After the intermediate transfer member is moved for a period of time, an image on the second surface of the first recording material on which the image is formed on the first surface being conveyed in the apparatus is transferred from the image carrier to the intermediate transfer member. The image of the second surface of the first recording material that has been primarily transferred to the first recording material is transferred to the first recording material. Control method characterized by transferring. In response to an instruction to start forming an image on the first surface of the second recording material on the image carrier, the image on the first surface of the second recording material that has not been supplied is displayed on the image carrier. the method according to claim 5 or 6 to form, the formed image, characterized in that primarily transferred to the intermediate transfer member. The image forming apparatus further includes a cleaner for cleaning the intermediate transfer member,
After the image is secondarily transferred to the second surface of the first recording material on which the image has been formed on the first surface being conveyed in the apparatus by the cleaner, the supplied first-transferred image on the intermediate transfer member is supplied. The control method according to claim 7 , wherein an image on the first surface of the second recording material that is not cleaned is cleaned.

Images