JP2012118136A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device provided with a configuration capable of negating the need of increasing in size, being complicated and further setting a time for a process other than an image forming process except an image forming time.SOLUTION: An image forming device 1 comprises: a transferring device for transferring a toner image carried by an image carrier to a recording medium; an accommodating section for a standard size mounted in the image forming device 1 beforehand as a feeding section of the recording medium; and a manual feeding section 5 capable of feeding the recording medium other than the standard size. The image forming device 1 is further provided with a configuration 100 for changing over a bias for transferring to a state different from that during transferring operation by targeting a period time in which a region, where the recording medium does not exist, of an image region moves as opposing to a transferring member in a case where a size of a recording sheet S fed from the manual feeding section 5 in a transferring direction is smaller than that of an image in the transferring direction.

Description

  The present invention relates to an image forming apparatus, and more particularly to a mechanism for transferring a visible image to a recording medium such as a recording sheet.

2. Description of the Related Art As is well known, in an image forming apparatus such as a copying machine, a printer, or a printing machine that uses an electrophotographic system, a development in which an electrostatic latent image formed on a photosensitive member that is a latent image carrier is supplied from a developing device. The visible image is processed by the agent.
The visible image-processed toner image is transferred to a transfer material, and is then fixed by heating and pressurizing with a fixing device so that the toner melts and permeates to form a copy image.

  Some image forming apparatuses are configured to form not only a single color but also a plurality of colors such as full colors. In this case, images of different colors formed in a plurality of image forming units are belted. The intermediate image is sequentially transferred (primary transfer) to the intermediate transfer member, and the superimposed image is transferred collectively (secondary transfer) to a recording medium such as a recording sheet (hereinafter sometimes referred to as a recording sheet for convenience). ) May be used.

By the way, an image that is superimposed and transferred to the intermediate transfer member in the primary transfer is generally transferred in advance to a recording medium selected in accordance with the image size (hereinafter also referred to as a recording sheet for convenience). For example, for example, a recording in which the size in the conveyance direction is erroneously smaller than the superimposed transfer image size from the manual paper feed tray, not from the paper feed cassette of the existing member containing the standard size recording sheet. Sheets may be fed.
In this case, there is a possibility that the image to be transferred exists on the intermediate transfer body even after the trailing end in the conveyance direction of the recording sheet passes the transfer position, and the toner contained in the image is transferred to the transfer member. is there.

When the toner is transferred to the transfer member, the toner adheres to the back surface of the recording sheet that is next fed toward the transfer position, causing back stain.
Conventionally, the following methods are known as countermeasures for solving such problems.
(A) A cleaning mechanism is provided on the transfer member (for example, Patent Documents 1 and 2).
(A) A size detection sensor is provided on the manual feed tray side.
(C) The size of the recording sheet fed from the manual feed tray is input in advance.
(D) When it is detected that the image size does not match the recording sheet using (a), the movement of the apparatus is stopped.

  However, when the cleaning mechanism is provided on the transfer member side, not only the configuration is increased, but also the time for removing the toner adhering to the transfer member is required. For this reason, the configuration and size of the image forming apparatus may be complicated and the removal time other than the time required for actual image formation may be added to increase the runtime of the image forming apparatus.

  An object of the present invention is to increase the size and complexity of the configuration and to perform image formation processing in addition to the image formation time in view of the problems in the conventional image forming apparatus described above, in particular, the configuration that prevents the back stain due to toner adhesion to the transfer member It is an object of the present invention to provide an image forming apparatus having a configuration capable of eliminating the time other than the above.

In order to achieve this object, the present invention has the following configuration.
(1) A transfer device that transfers a toner image carried on an image carrier to a recording medium is provided. As a feeding unit for the recording medium, a storage unit for a standard size that is provided in the apparatus in advance, and the standard In an image forming apparatus including a manual feeding unit capable of feeding a recording medium other than the size,
The transfer device includes: a transfer member that contacts the image carrier; and a toner that is carried on the image carrier by forming an electric field at a transfer portion that corresponds to a contact position between the image carrier and the transfer member. Comprising an electric field forming device for transferring to a recording medium,
The electric field forming device is provided with a transfer bias switching means to be applied to the transfer section, and the transfer bias switching means is configured such that the size of the recording medium in the conveyance direction from the manual feeding section is an image on the image carrier. When the recording medium does not exist at least in the area corresponding to the image area on the image carrier side, the area where the recording medium does not exist is opposed to the transfer member. An image forming apparatus comprising a configuration in which a transfer bias is switched and changed to a state different from that at the time of transfer for a time during movement.

(2) The transfer bias switching unit is connected to a control unit that performs an image formation control process on the image carrier.
The control unit includes a size detection unit capable of detecting a conveyance direction size of the recording medium fed from the manual feeding unit and an image formation processing unit connected to the input side, and the transfer bias switching unit on the output side. Connected,
When the conveyance direction size of the recording medium continuously fed from the manual feeding unit is smaller than the size in the corresponding direction in the image on the image carrier, the area in the corresponding direction of the image where the recording medium does not exist Switching to bias application having a polarity opposite to that at the time of transfer, and temporarily stopping image formation to be transferred, to a recording medium having a conveyance direction size corresponding to the corresponding direction size of the image in the manual feeding portion. Before the replacement, a warning is given, and the image formation to be transferred is resumed when the recording medium having the conveyance direction size corresponding to the image size is replaced and the manual feed resumption command is input. (1) The image forming apparatus according to (1).

(3) When the conveyance direction size of the recording medium continuously fed from the manual feeding unit is smaller than the corresponding direction size in the image, the control unit temporarily stops image formation to be transferred, and then manually feeds the recording medium. When a manual feed restart instruction is input from the feeding unit to a recording medium having a size in the transport direction corresponding to the image size, transfer is resumed for the image at the time of the temporary stop. (2) The image forming apparatus according to (2).

  According to the present invention, when the conveyance direction size of the recording medium fed from the manual feeding unit is smaller than the corresponding direction size in the image on the image carrier, the transfer is performed on the image area where the recording medium does not exist. The bias is switched to a state different from that at the time of transfer. In particular, the bias is switched to a direction opposite to the toner transfer direction at the time of transfer. As a result, the toner in the area where no image is present is repelled from the transfer member side, so that adhesion of the toner to the transfer member is suppressed and the backside of the recording medium can be prevented. As a result, since it is not necessary to provide a cleaning mechanism for the transfer member, it is possible to suppress an increase in the size of the apparatus and an increase in running time.

1 is a schematic diagram for explaining a configuration of an image forming apparatus according to the present invention. It is a figure for demonstrating an effect | action with the structure concerning transfer shown in FIG. It is a figure for demonstrating the malfunction in the conventional structure shown in FIG. It is a figure which expands and shows the generation | occurrence | production state of the malfunction shown in FIG. FIG. 4 is an enlarged view for explaining the operation at a transfer section shown in FIG. 3. FIG. 3 is a diagram for explaining a main configuration and an operation of the image forming apparatus according to the present invention. It is a block diagram for demonstrating the structure of the control part used for the image forming apparatus shown in FIG. FIG. 8 is a timing chart for explaining a transfer bias switching state executed by the control unit shown in FIG. 7. FIG. It is a flowchart regarding the 1st control performed by the control part shown in FIG. It is a flowchart regarding the 2nd control performed by the control shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings, but before that, a transfer process and problems in a conventional image forming apparatus will be described.
FIG. 1 is a view showing an image forming apparatus used in an embodiment of the present invention for explaining a conventional image forming apparatus. The image forming apparatus 1 shown in FIG. 1 is a transfer belt 1A used as an intermediate transfer member. This is a tandem type image forming apparatus in which a plurality of image forming units are arranged side by side along the extending direction.
In the figure, the image forming apparatus 1 is provided with image forming units capable of forming images of different colors along the extending direction of the intermediate transfer belt 1A used in the primary transfer device. Photosensitive drums 1Y, 1M, 1C, and 1Bk that carry toner images formed by a writing mechanism and a developing device are provided.
On the other hand, transfer devices 2Y, 2M, 2C, and 2Bk for transferring an image from the photosensitive drum to the intermediate transfer belt 1A are disposed at positions facing the respective photosensitive drums with the intermediate transfer belt 1A interposed therebetween.
The intermediate transfer belt 1A is wound around a plurality of rollers 1A1 and 1A2 and moves in the direction of the arrow in the figure. One roller 1A1 is located at the position where the image transfer is completed at each image forming unit. Is opposed to a secondary transfer roller 3 as a secondary transfer device.
The position at which the intermediate transfer belt 1A and the secondary transfer roller 3 face each other corresponds to a transfer unit that collectively transfers the images superimposed and transferred onto the intermediate transfer belt 1A. The superimposed image is collectively transferred to the recording sheet S that is one of the recording media to be fed. After the batch transfer, the intermediate transfer belt 1A is cleaned by removing residual toner by the cleaning device 1B.
The recording sheet S can be fed from the manual feeding unit 5 in addition to the sheet feeding device 4 including the sheet feeding cassette 4A that stores a recording sheet of a fixed size toward the transfer unit. It is like that.
A fixing device 6 is disposed on the conveyance path of the recording sheet S on which the superimposed images are collectively transferred from the intermediate transfer belt 1A in the transfer unit, and the image transferred to the recording sheet S is heated and fixed, and a discharge unit (not shown). It is going to be discharged towards.
The manual feed portion 5 described above is configured by a manual feed tray 5A provided so that a part of the wall surface of the image forming apparatus 1 can be opened and closed, and a feed roller 5B provided on the recording sheet feed side of the manual feed tray 5A. When the recording sheet is placed, it can be fed out toward the transfer portion. The recording sheet S fed out from either the paper feed cassette 4A or the manual feed tray 5A is fed toward the transfer section after the registration timing is set by the registration rollers 7 before reaching the transfer section.
On the other hand, as shown in FIG. 2A, the manual feed tray 5A has a size detection sensor (for the sake of convenience) that detects the size of the recording sheet placed in the conveyance direction (the direction indicated by the arrow in FIG. 2B). , Indicated by reference numeral 8 ').
The size detection sensor 8 ′ detects all sizes of the recording sheet fed from the manual feed tray 5A, and checks, for example, the consistency between the image size carried on the intermediate transfer belt 1A and the recording sheet size. It can be done. For this reason, the manual feed tray 5A has a considerable length to correspond to the size of the recording sheet in the conveyance direction, which leads to an increase in the size of the apparatus.
Therefore, as shown in FIG. 2B, the position where the recording sheet conveyance path from the manual feeding unit 5 and the recording sheet conveyance path from the sheet feeding device 4 merge, that is, the front side of the registration roller 7. A size detection sensor (indicated by reference numeral 8 for the sake of convenience) is arranged at the position of FIG. 2, and the size of the recording sheet can be detected for both conveying paths as shown in FIG. 2C. As the size detection sensor 8, an optical sensor or the like is used, and the size of the recording sheet that is actually conveyed can be detected by detecting the movement time based on the conveyance speed of the recording sheet and the size that is input in advance. It is used.
In this configuration, since the size detection is not provided on the manual feed tray 5A side, it is not necessary to increase the size of the manual feed tray 5A.
On the other hand, a transfer bias for transferring the superimposed image carried on the intermediate transfer belt 1A toward the recording sheet S is applied to the transfer unit.
FIG. 3 is a diagram for explaining the configuration and operation of the transfer unit. In FIG. 3, one of the rollers around which the intermediate transfer belt 1A is wound, that is, the secondary transfer roller 3 as a transfer member is opposed. A bias having the same polarity as that of the carried toner is applied to the roller 1A1, and the toner image carried on the intermediate transfer belt 1A is caused to fly toward the recording sheet S to be transferred. . As shown in FIG. 3B, the transfer bias at this time is applied so as to cover the image area width along the moving direction of the intermediate transfer belt 1A, that is, the moving direction parallel to the recording sheet conveyance direction at the transfer portion. The time is set.
FIG. 4 is a diagram for explaining a problem in the image forming apparatus having the above-described configuration. In FIG. 4, the back-stain phenomenon on the recording sheet S due to transfer of toner to the secondary transfer roller 3 used as a transfer member. It is shown.
When image transfer is performed on the recording sheet S from the manual feeding unit 5, the recording sheet S of unknown size may be erroneously fed.
In this case, the image size is different from the size of the recording sheet. In particular, the size of the recording sheet rather than the image size, specifically, the size in the conveyance direction of the recording sheet is the corresponding direction size in the image, that is, transfer. The size may be smaller than the size in the direction of movement in the direction along the conveyance direction of the recording paper.
FIG. 4A shows a state in which a certain amount of time has elapsed since the transfer of the image carried on the intermediate transfer belt 1A to the recording sheet S fed from the manual feeding unit 5 is started. In this state, based on the transfer bias shown in FIG. 3, the toner on the intermediate transfer belt 1 </ b> A (denoted by reference numeral T <b> 1 for convenience) is transferred toward the recording sheet S.
On the other hand, as shown in FIG. 4B, when the size of the recording sheet S in the conveyance direction (arrow direction shown in the figure) is smaller than the size in the corresponding direction of the image, the image still remains on the intermediate transfer belt 1A. Nevertheless, the rear end of the recording sheet S in the conveyance direction is separated from the image portion, and the untransferred toner (indicated by reference numeral T2 for convenience) on the intermediate transfer belt 1A faces the secondary transfer roller 3. When the transfer bias shown in FIG. 3 is continued, the toner T2 on the intermediate transfer belt 1A is transferred toward the secondary transfer roller 3 because there is no recording sheet S, and adheres to the surface of the secondary transfer roller 3. .
As shown in FIG. 4C, the toner T2 adhering to the secondary transfer roller 3 is re-transferred and adhered to the back surface of the recording sheet S to be fed next, resulting in backside contamination.
FIG. 5 is an enlarged view of the state shown in FIG. 4C, in which the toner on the intermediate transfer belt 1A moves toward the secondary transfer roller 3 under the action of the electric field due to the transfer bias. Become.
Conventionally, as a method for preventing toner from adhering to the secondary transfer roller 3 to prevent the recording sheet S from being stained, a cleaning mechanism is provided for the secondary transfer roller 3 to remove the adhered toner. In addition, it is conceivable to detect the recording sheet fed from the manual feeding unit or to input the size in advance to determine the matching with the image size, and when it is different, interrupt the transfer and warn. However, there is a possibility of causing problems such as an increase in the size of the apparatus due to the attachment of the mechanism and a part of the image not being transferred to the recording sheet depending on the timing of the interruption process.
The above is a problem in the conventional image forming apparatus, and the present invention is characterized in that this problem is solved. Examples of the present invention will be described below.
As in the case shown in FIG. 1, the present invention includes a plurality of image forming portions in the extending direction of the intermediate transfer belt 1 </ b> A, and further, the images transferred onto the intermediate transfer belt 1 </ b> A are collectively transferred by the secondary transfer roller 3. It is intended for a transfer configuration.
FIG. 6 is a diagram illustrating a configuration of a transfer unit that performs batch transfer in the image forming apparatus illustrated in FIG. 1.
In FIG. 6, as the transfer device used for batch transfer, one of the rollers 1A1 around which the intermediate transfer belt 1A is wound and the secondary transfer roller 3 opposite thereto are used, and the intermediate transfer belt is used as the transfer device. An electric field forming device 9 is provided for forming an electric field for transferring the toner carried on 1A toward the recording sheet S in the transfer portion.
The electric field forming device 9 is provided with a transfer bias switching unit 9A. The transfer bias switching unit 9A is set with a polarity for transferring the toner on the intermediate transfer belt 1A toward the recording sheet S and is applied during transfer. Switching between a transfer bias (see FIG. 6 (A)) and a recovery transfer bias (see FIG. 6 (B)) in which the polarity opposite to the transfer bias is set and toner can be attracted to the intermediate transfer belt 1A side. Can be done.
On the other hand, the operation of the transfer bias switching means 9A provided in the electric field forming device 6 is controlled by the control unit 100 shown in FIG.
In FIG. 7, the control unit 100 uses a control unit that performs image formation sequence control. As a member related to the present embodiment, the input side has a standard size as shown in FIG. The size detection sensor 8 provided at a position where the conveyance path of the recording sheet from the cassette that accommodates the recording sheet and the conveyance path of the recording sheet from the manual feed tray 5A of the manual feeding unit 5 merge and the feeding state. An operation panel 101 having a warning display unit (not shown) for instructing printing condition settings including selection and the number of prints and displaying various warnings is connected. On the output side, the transfer bias switching means 9A and image forming unit are connected. The image forming processing unit 102 is connected. The image forming processing unit 102 is a driving unit for setting a withstand voltage characteristic, a writing timing and a writing light amount in a charging device or a writing device provided in the image forming unit, a toner density management unit provided in a developing device, or the like. Is equipped with a drive unit.
In the control unit 100, when the conveyance direction size of the recording sheet fed from the manual feeding unit 5 is different from the corresponding direction size of the image carried on the intermediate transfer belt 1A, specifically, the recording is performed more than the image size. When the sheet length is short, a transfer bias different from that at the time of transfer, that is, toner is applied to the recording sheet S during the time in which an area where no recording sheet exists in the image area moves opposite to the secondary transfer roller 3. The polarity is changed over to the intermediate transfer belt 1 </ b> A instead of the recovery transfer bias having the polarity.
In the control unit 100 that performs bias switching due to such a size mismatch, the length of the image area in the movement direction corresponding to the conveyance direction length of the recording sheet S is registered in advance based on the writing time based on the image information. In this case, the time for the trailing end of the conveyance direction to reach the transfer unit is determined from the conveyance speed of the recording sheet, and when the conveyance direction length of the recording sheet is shorter than the image area, the size detection sensor 6 causes the conveyance direction of the recording sheet. The transfer bias is switched to the transfer bias for collection after the elapse of time from the time when the rear end is detected to the transfer portion.
FIG. 8 is a timing chart showing the operation timing of the transfer bias switching means 6A.
As shown in the figure, a transfer bias (−2 kV) is applied while the recording sheet passes through the transfer portion, and the transfer bias is switched to the recovery transfer bias (+2 kV) when the rear end of the recording sheet in the transport direction passes through the transfer portion.
In the embodiment as described above, when a recording sheet of unknown size is erroneously fed from the manual feeding unit 5 and the recording sheet is smaller than the image size, transfer in an image area where no recording sheet exists is performed. Transfer of toner to the secondary transfer roller 3 is suppressed only by switching the bias to the characteristic of transferring and collecting the toner to the intermediate transfer belt 1A side. For this reason, there is no need to provide a cleaning mechanism for the secondary transfer roller 3. Thereby, the enlargement of the apparatus which becomes a cause by providing a special mechanism can be prevented.
In addition, since the timing for preventing toner adhesion to the secondary transfer roller 3 is within the image forming area carried by the intermediate transfer belt 1A, the secondary transfer roller is cleaned after the image forming area has passed the transfer portion. There is no need to perform processing. In other words, a measure for preventing the toner from adhering to the secondary transfer roller is taken while one image forming area passes through the transfer portion, so that no cleaning time other than the transfer time is set. Therefore, it is possible to prevent the image forming cycle from being inadvertently lengthened.
In particular, when preventing the toner from adhering to the secondary transfer roller 3, the secondary transfer roller 3 is applied to the intermediate transfer belt 1A so that the recording sheet can be nipped and conveyed in the same manner as in normal image transfer. Since the contacted state is maintained, the transportability of the recording sheet does not change.
Next, another embodiment of the present invention will be described.
In this embodiment, when the recording sheet S is continuously fed from the manual feeding unit 5, particularly when the recording sheet having a small conveyance direction size with respect to the image size is continuously fed. It is a feature.
That is, the control unit 100 executes processing based on the flowchart shown in FIG.
In FIG. 9, when a continuous printing signal using a recording sheet from the manual feed tray 5 </ b> A is input to the control unit 100, the control unit 100 outputs a signal for a continuous printing command to the image forming processing unit 101. (ST1, ST2).
When continuous feeding of recording sheets from the manual feed unit 5 is started (ST3), the size of the recording sheet in the conveyance direction is detected by the size detection sensor 8 (ST4).
In the size detection, for example, when it is detected that the conveyance direction size of the recording sheet to be conveyed is smaller than the corresponding direction size in the image (ST5), the image area where the recording sheet does not exist even though the image exists In the control unit 100, as shown in FIG. 6B, the transfer bias switching means 9A is switched from the transfer bias to the state of setting the recovery transfer bias (ST6).
On the other hand, the transfer bias for collection is set, and the image forming process and the subsequent feeding of the recording sheet from the manual feed tray 5A are interrupted (ST7), and the recording sheet before being interrupted, that is, the image transfer is performed. The performed recording sheet and the recording paper to be interrupted are each discharged (ST8). The processing in step ST7 takes into account the case where the recording sheet is already fed out from the manual feed tray 5A at the time when the image forming processing is interrupted during continuous feeding. Thus, the processing is performed when the image forming processing is interrupted. The recording sheet is discharged without image transfer.
At the time of interruption, a warning is given that the size of the recording sheet is different from the image size (ST9), and the operator follows the warning and replaces the recording sheet with a size corresponding to the image size to restart the feeding from the manual feeding unit 5 Is input again (ST10), the size of the recording sheet is detected again (ST11), and the recording sheet from the manual feeding unit 5 is targeted only when the sizes of the image and the recording sheet match. Image transfer is resumed (ST12).
In this embodiment, when the operator does not recognize that the size of the recording sheet is different from the image size, a warning can be given to prompt the user to match the sizes. This prevents the transfer of the lost image and prevents unnecessary printing.
Next, still another embodiment of the present invention will be described.
The present embodiment is characterized by processing at the start of printing after interruption in the processing shown in FIG. That is, when printing is interrupted, the image at the time when printing is resumed may start from the next image at the time when printing is interrupted. It is intended to resume targeting.
FIG. 10 is a flowchart showing this processing.
In FIG. 10, the conveyance direction size of the second recording sheet matches the corresponding direction size in the image by continuous feeding from the manual feeding unit 5, and the conveyance direction size of the third recording sheet is the image size. If the size is smaller than the size, as described with reference to FIG. 9, after the image formation is temporarily stopped, the size of the recording sheet is corrected by the operator, and a restart instruction for printing (image formation processing) is indicated. Transfer is performed on the recording sheet fed after resuming the third image. As a result, even if an image having a defect such as an image defect is transferred to a part of the continuously fed recording sheet, the image having the image defect is displayed on the first recording sheet discharged when printing is resumed. Since the image is transferred in the correct state, even if a recording sheet having an image defect is overlooked, a plurality of recording sheets on which normal image transfer has been performed can be obtained.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Intermediate transfer belt 3 Secondary transfer roller 4 Paper feeding device 5 Manual feed unit 8 Size detection sensor 9 Electric field forming device 9A Transfer bias switching means 100 Control unit 101 Operation panel 102 Image forming processing unit

Japanese Patent Laid-Open No. 03-69978 JP 2005-70750 A

Claims (3)

A transfer device that transfers a toner image carried on the image carrier to a recording medium, and a storage unit for a standard size that is provided in the apparatus in advance as a feeding unit for the recording medium; In an image forming apparatus including a manual feeding unit capable of feeding a recording medium,
The transfer device includes: a transfer member that contacts the image carrier; and a toner that is carried on the image carrier by forming an electric field at a transfer portion that corresponds to a contact position between the image carrier and the transfer member. Comprising an electric field forming device for transferring to a recording medium,
The electric field forming device is provided with a transfer bias switching means to be applied to the transfer section, and the transfer bias switching means is configured such that the size of the recording medium in the conveyance direction from the manual feeding section is an image on the image carrier. When the recording medium does not exist at least in the area corresponding to the image area on the image carrier side, the area where the recording medium does not exist is opposed to the transfer member. An image forming apparatus comprising a configuration in which a transfer bias is switched and changed to a state different from that at the time of transfer for a time during movement. The transfer bias switching means is connected to a control unit that performs image formation control processing on the image carrier,
The control unit includes a size detection unit capable of detecting a conveyance direction size of the recording medium fed from the manual feeding unit and an image formation processing unit connected to the input side, and the transfer bias switching unit on the output side. Connected,
The conveyance direction size of the recording medium continuously fed from the manual feed unit is smaller than the size in the corresponding direction in the image on the image carrier, and the area in the corresponding direction of the image where the recording medium does not exist The target is switched to bias application having a polarity opposite to that at the time of transfer, and when the continuous feeding from the manual feeding unit is performed, it is determined that the conveyance direction size of the recording medium is smaller than the corresponding direction size in the image. The image formation to be transferred is temporarily stopped and a warning is given until the manual feed section is replaced with a recording medium having a conveyance direction size corresponding to the corresponding direction size of the image. The image forming is resumed when it is replaced with a recording medium having a conveyance direction size corresponding to the input and a manual feed resumption command is input. The image forming apparatus according to claim 1.   The control unit temporarily stops image formation to be transferred when the conveyance direction size of the recording medium continuously fed from the manual feeding unit is smaller than the corresponding direction size in the image, and then the image from the manual feeding unit. The transfer is executed on the image at the time when it is temporarily stopped when a manual feed resume command is input after the recording medium is changed to a recording medium having a conveyance direction size corresponding to the size. The image forming apparatus described.

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