Image forming device

Abstract

To solve the problem in which: when paper jam occurs during printing, a user removes only a jammed sheet that has caused the paper jam while not aware of the presence of a sheet subsequent to the jammed sheet, and thus the paper jam may not properly handled.SOLUTION: An image forming apparatus has: an image forming unit 19 that forms an image on a recording sheet 25; a plurality of conveying rollers (11, 13, 15, 17) that conveys the recording sheet 25 to the image forming unit 19; a paper jam detection unit 107 that detects paper jam caused by the recording sheet 25; a sheet detection unit 108 that detects the recording sheet 25 by using a paper feed sensor 12 arranged upstream of the image forming unit 19 in a conveyance direction; and a subsequent sheet conveying unit 111 that controls drive of the plurality of conveying rollers (11, 13, 15, 17). When the paper jam detection unit 107 detects the paper jam caused by the recording sheet 25 and the sheet detection unit 108 detects a subsequent sheet 25R subsequent to a jammed sheet 25J, the subsequent sheet conveying unit 111 controls to convey the subsequent sheet 25R by a predetermined amount in the conveyance direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer, and more particularly to the transport of recording paper. [Background technology]

[0002] In the past, when a jammed sheet was downstream of the most upstream drum and subsequent sheets had not been transported to the waiting position, the paper feed motor was reversed to pull the sheet back, making it easier to remove the sheet (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-46204 A (page 9, FIG. 4) Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a jam occurs during printing, the user may remove only the jammed paper without noticing the presence of paper following the jammed paper that caused the jam, which may result in the jam not being properly dealt with. [Means for solving the problem]

[0005] The image forming apparatus according to the present invention includes an image forming unit that forms an image on a sheet of paper, a plurality of transport rollers that transport the sheet of paper to the image forming unit, a jam detection unit that detects a jam of the sheet of paper, and a first sheet sensor that is disposed upstream of the image forming unit in the transport direction. and a second paper sensor disposed downstream of the first paper sensor in the transport direction. a sheet detection unit that detects the sheet by a sheet detection signal; and a conveyance control unit that controls the driving of the plurality of conveyance rollers. a conveyance distance determination unit that determines a conveyance distance of a subsequent sheet following the jammed sheet when the jammed sheet is detected by the second sheet sensor by the sheet detection unit; With The transport control unit controls the transport rollers to transport the subsequent sheet a predetermined amount in the transport direction when the jam detection unit detects a jam of the sheet and the sheet detection unit detects the subsequent sheet with the first sheet sensor, transports the subsequent sheet until the second sheet sensor detects it when the jammed sheet is not detected by the second sheet sensor, and transports the subsequent sheet based on the transport amount determined by the transport amount determination unit when the second sheet sensor detects the jammed sheet. . [Effects of the Invention]

[0006] According to the image forming apparatus of the present invention, when removing a jammed sheet, the subsequent sheet can also be easily removed. In addition, since the jammed sheet and the subsequent sheet are located close to each other, it is possible to prevent forgetting to remove the subsequent sheet. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating a configuration of a main part of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing a configuration of a main part of a control system of an image forming apparatus according to a first embodiment of the present invention. [Figure 3] 10 is a flowchart showing the flow of a jam handling process when a jam occurs in the first embodiment. [Figure 4] This figure is used to explain paper transport when a jam occurs in embodiment 1, where (a) shows the state at the time the jam occurs, (b) shows the position of the subsequent paper before the transport process when the trailing end of the preceding paper where the jam occurred has passed the second entrance sensor, (c) shows the position of the subsequent paper after the transport process when the trailing end of the preceding paper where the jam occurred has passed the second entrance sensor, (d) shows the position of the subsequent paper before the transport process when the trailing end of the jammed paper has not passed the second entrance sensor, and (e) shows the position of the subsequent paper after the transport process when the trailing end of the jammed paper has not passed the second entrance sensor. [Figure 5] FIG. 10 is a block diagram showing a configuration of a main part of a control system of an image forming apparatus according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart showing the flow of a jam handling process when a jam occurs in the second embodiment. [Figure 7] This figure is used to explain paper transport when a jam occurs in embodiment 2, where (a) shows the position of jammed paper 25J and subsequent paper 25R before the transport process when the rear end of the jammed paper has not yet passed the distance S from the first pair of resist rollers, and (b) shows the state of the jammed paper and the position of the subsequent paper after the transport process. DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiment 1 FIG. 1 is a schematic diagram illustrating the configuration of a main part of an image forming apparatus 1 according to a first embodiment of the present invention.

[0009] As shown in the figure, the image forming device 1 has a paper transport path 24 formed inside, and arranged from the upstream side are a paper tray 10, a medium feed roller 11, a paper feed sensor 12, a pair of resist intermediate rollers 13, a first entrance sensor 14, a first pair of resist rollers 15, a second entrance sensor 16, a second pair of resist rollers 17, a write sensor 18, an image forming section 19, a fixing section 20, a discharge sensor 21, and a pair of discharge rollers 22.

[0010] The paper tray 10 contains recording paper 25, and the medium feed roller 11 sequentially discharges the topmost sheet of recording paper 25 stacked in the paper tray 10 toward the downstream side of the conveyance path. The paper feed sensor 12, which serves as a first paper sensor, detects the recording paper 25 sent out to the conveyance path by the medium feed roller 11 and transmits the detection information to a paper detection unit 108 (FIG. 2), which will be described later. The registration intermediate roller pair 13 consists of a drive roller that is driven to rotate and a pressure roller that is in pressure contact with the drive roller and is driven to convey the recording paper 25 downstream.

[0011] The medium feed roller 11 is rotated only when the recording paper 25 is removed from the paper tray 10, and is then equipped with a ratchet mechanism so that it rotates in response to the movement of the recording paper 25 transported by the first registration roller pair 15, etc.

[0012] The first inlet sensor 14 detects the recording paper 25 being transported by the registration intermediate roller pair 13 and sends the detection information to a paper detection unit 108 (FIG. 2) described later. The first registration roller pair 15 consists of a drive roller that is driven to rotate and a pressure roller that is in pressure contact with the drive roller and is driven by the drive roller, and transports the recording paper 25 sent out from the registration intermediate roller pair 13 further downstream.

[0013] The second entrance sensor 16, which serves as a second paper sensor, detects the recording paper 25 being transported along the paper transport path 24 and sends the detection information to the paper detection unit 108 (FIG. 2), which will be described later. The second registration roller pair 17 similarly consists of a drive roller and a pressure roller that is in pressure contact with the drive roller and is driven by the drive roller, and rotates at a predetermined timing, which will be described later, to correct skew in the recording paper 25 and transport the recording paper 25 downstream. The writing start sensor 18 detects the recording paper 25 being transported along the paper transport path 24 and sends the detection information to the paper detection unit 108 (FIG. 2), which will be described later. The medium feed roller 11, the registration intermediate roller pair 13, the first registration roller pair 15, and the second registration roller pair 17 correspond to multiple transport rollers.

[0014] The image forming unit 19 transfers a toner image formed on a photosensitive drum 19a based on image data onto a recording paper 25 transported downstream along a paper transport path 24 using a transfer roller 19b, and transports the transferred recording paper 25 to a fixing unit 20.

[0015] The fixing unit 20 includes a heating roller 20a and a pressure roller 20b that rotates in contact with the heating roller 20a, and applies heat and pressure to the conveyed recording paper 25, fixes the toner image transferred onto the recording paper 25, and discharges the recording paper 25 downstream in the conveyance direction. The discharge sensor 21 detects the recording paper 25 discharged from the fixing unit 20 and transmits the detection information to a paper detection unit 108 (FIG. 2) described later.

[0016] The discharge roller pair 22 comprises a drive roller that is driven to rotate and a pressure roller that is in pressure contact with the drive roller and is driven to discharge the printed recording paper 25 sent from the fixing unit 20 onto the discharged paper tray 23. Therefore, the recording paper 25 that has been printed sequentially by the above-mentioned process is piled up on the discharged paper tray 23.

[0017] A top cover 42 of the image forming apparatus 1 includes a pair of discharge rollers 22 and a discharge paper tray 23, and is supported by a bottom frame 41 so as to be rotatable about a rotation shaft 43. For example, by rotating the top cover 42 from a closed position in the direction of arrow A to open it, maintenance of the fixing unit 20, the image forming unit 19, and the conveyance system for recording paper 25, which are arranged inside the image forming apparatus 1, becomes possible. In addition, an operation / display unit 113 is arranged at the top front of the top cover 42, which includes an operation unit for the user and a display unit that displays the device status, etc.

[0018] FIG. 2 is a block diagram showing a configuration of a main part of a control system of image forming apparatus 1 according to the first embodiment of the present invention.

[0019] The system control unit 101 controls the entire image forming apparatus 1, receives command reception results from the connection I / F unit 102, and activates the print control unit 104, jam control unit 120, and operation / display unit 113 to execute processing. The system control unit 101 also stores the received image data in the image data storage unit 103.

[0020] The connection I / F unit 102 connects to a local area network (hereinafter referred to as a LAN line) and performs Transmission Control Protocol / Internet Protocol (hereinafter referred to as TCP / IP) control. The image data storage unit 103 is a hard disk built into the image forming apparatus 1 and stores received print data.

[0021] The printing control unit 104 gives instructions to each control unit to control the printing operation, the medium feeding control unit 105 controls the medium feeding mechanism including the medium feeding roller 11 to feed the recording paper 25 to the paper transport path 24, and the medium transport control unit 106 controls the transport of the recording paper 25 fed by the medium feeding control unit 105 until it is discharged onto the discharge paper loading tray 23.

[0022] The jam control unit 120 has a jam detection unit 107 that checks whether the on / off of each sensor arranged corresponding to the paper transport path 24, such as the discharge sensor 21 that detects the transported recording paper 25, is operating at a predetermined timing, and determines that a jam has occurred if these sensors do not turn on / off normally. Furthermore, when a jam is detected during continuous printing, the jam control unit 120 also has a paper detection unit 108 that detects whether there is a subsequent paper 25R following the jammed paper 25J (previous paper) where the jam occurred, a transport feasibility determination unit 109 that determines whether the subsequent paper can be transported, a transport distance calculation unit 110 that calculates the transport distance of the subsequent paper based on the trailing edge position of the previous paper, and a subsequent paper transport unit 111 that serves as a transport control unit that transports the subsequent paper based on the calculated transport distance. The transport feasibility determination unit 109 and the transport distance calculation unit 110 correspond to a transport distance determination unit.

[0023] In addition, the paper feed sensor 12, the first entrance sensor 14, the second entrance sensor, the write sensor 18, and the discharge sensor 21 here transmit an ON signal while they are detecting the conveyed recording paper 25, and transmit an OFF signal while they are not detecting it.

[0024] The fixing control unit 112 controls the temperature of the heating roller 20a of the fixing unit 20 to fix the toner. The operation / display unit 113 consists of an operation unit with menu keys necessary for operating the image forming apparatus 1, setting keys for entering operation confirmations and start instructions, and a cancel key for stopping operations, and a display unit that displays input information and alarm information. The memory unit 114 is a volatile storage device that stores data used by the device. This memory unit 114 includes a print control data storage unit 115 that stores print control information, and a width setting information unit 116 based on fixing temperature.

[0025] In the above configuration, a jam handling process when a jam occurs in the image forming apparatus 1 of this embodiment will be described with reference to FIGS.

[0026] Figure 3 is a flowchart showing the flow of jam response processing when a jam occurs, and Figure 4 is a diagram used to explain paper transport when a jam occurs, where (a) shows the state at the time the jam occurred, (b) shows the position of the subsequent paper before the transport process when the trailing end of the preceding paper where the jam occurred has passed the second entrance sensor 16, (c) shows the position of the subsequent paper after the transport process when the trailing end of the preceding paper where the jam occurred has passed the second entrance sensor 16, (d) shows the position of the subsequent paper before the transport process when the trailing end of the jammed paper has not yet passed the second entrance sensor 16, and (e) shows the position of the subsequent paper after the transport process when the trailing end of the jammed paper has not yet passed the second entrance sensor 16.

[0027] The connection I / F unit 102 receives the command, analyzes the received command, determines that the request command is a print request, and notifies the system control unit 101 that a print request command has been received. Upon receiving the notification, the system control unit 101 generates print data based on the print information specified in the header of the received data, and instructs the print control unit 104 to start printing.

[0028] Upon receiving the print start instruction, print control unit 104 causes medium feed control unit 105, medium transport control unit 106, jam control unit 120, and fixing control unit 112 to start printing (step S101). Note that the printing operations performed by these control units in response to instructions, other than paper transport as described below, are printing operations performed by a normal electrophotographic process, and therefore detailed explanations thereof will be omitted here.

[0029] If the jam detection unit 107 does not detect a jam (step S102, No), printing operations will be performed for the number of sheets in the job during this time. On the other hand, if the jam detection unit 107 detects a jam during printing (step S102, Yes), for example, as shown in Figure 4(a), this occurs when the leading edge of the jammed recording paper (hereinafter referred to as jammed paper) 25J does not turn on the discharge sensor 21 at the specified timing.

[0030] In this case, the conveying operation for printing on the recording paper 25 is temporarily stopped, and the paper detection unit 108 checks whether there is a recording paper (hereinafter referred to as a succeeding paper) 25R behind the jammed paper 25J (step S103). If there is no succeeding paper 25R, the flow ends (step S103, No). As shown in FIG. 4(b), if the presence of the succeeding paper 25R is detected (here, detected by the paper feed sensor 12) (step S103, Yes), the conveyance possibility determination unit 109 checks whether the jammed paper 25J has turned off (passed through) the second inlet sensor 16 (step S104).

[0031] Here, if the jammed sheet 25J has turned off (passed through) the second entrance sensor 16 as shown in Fig. 4(b) (Yes in step S104), the subsequent sheet transport unit 111 transports the subsequent sheet 25R to the second entrance sensor 16 as shown in Fig. 4(c) (step S105). On the other hand, if the second entrance sensor 16 is turned on (has not yet passed through) (No in step S104), the sheet detection unit 108 checks how far the jammed sheet 25J has been transported, the transport amount calculation unit 110 calculates the transportable transport distance S1 that makes it easier to remove the subsequent sheet 25R (step S106), and the subsequent sheet transport unit 111 drives the registration intermediate roller pair 13 and the first registration roller pair 15 to transport the subsequent sheet 25R by the distance S1 (step S107).

[0032] Here, a method for calculating the transport distance S1 and the like in the transport amount calculation unit 110 in step S106 will be described.

[0033] For example, in Figure 4(d), a position a distance S downstream from the first registration roller pair 15 is visible to the user by opening the top cover 42 (Figure 1), and indicates a preferred guide position for removing the subsequent sheet 25R. In other words, the guide position of distance S is a position where the leading edge of the subsequent sheet 25R can be removed if it is transported at least up to that point. However, if the jammed sheet (previous sheet) 25J can be transported to a position a distance (S+α) near the trailing edge, as shown in Figure 4(e), the removal work becomes easier.

[0034] Therefore, assuming that the distance from the vicinity of the leading edge of the succeeding sheet 25R to the first inlet sensor 14 is N, the distance from the first inlet sensor 14 to the first registration roller pair 15 is D, the distance from the first inlet sensor 14 to the vicinity of the rear edge of the jammed sheet 25J is X, and the conveyance distance from the vicinity of the leading edge of the succeeding sheet 25R to the vicinity of the rear edge of the jammed sheet 25J is S1, the conveyance amount calculation unit 110 calculates the conveyance distance S1 as follows: S1=(=N+D+S+α) The distance α is the distance from the position at a distance S downstream from the first registration roller pair 15, which is the target position, to the vicinity of the rear end of the jammed sheet 25J.

[0035] On the other hand, the transport amount calculation unit 110 may calculate the distance X (= D + S + α) as the transport amount. In this case, however, the subsequent sheet transport unit 111 first starts transporting the subsequent sheet 25R in step S107, and then transports the subsequent sheet 25R by the distance X after the first inlet sensor 14 detects the leading edge of the subsequent sheet 25R.

[0036] Furthermore, the leading edge position of the subsequent sheet 25R required to determine the distance N can be determined, for example, by calculating the distance the sheet is transported by the pair of resist intermediate rollers 13 from the time the leading edge of the subsequent sheet 25R passes the paper feed sensor 12 until the jam is detected, and the trailing edge position of the jammed sheet 25J required to determine the distance α can be determined, for example, by calculating the distance the sheet is transported by the first pair of resist rollers 15 from the time the jammed sheet 25J passes the first entrance sensor 14 until the jam is detected.

[0037] When the flow has finished passing through each path and the printing operation has stopped, the user opens the top cover 42 (FIG. 1) of the image forming apparatus 1 and removes the jammed sheet 25J and the subsequent sheet 25R.

[0038] Here, an example has been shown in which the subsequent sheet 25R is conveyed a conveying distance S1 after a jam occurs, but the present invention is not limited to this, and the subsequent sheet 25R may be conveyed, for example, to a target position (a position at a distance S from the first pair of registration rollers 15). In this case, the subsequent sheet conveying unit 111 may convey the subsequent sheet 25R by a distance (N+D+S), for example, in step S107, or may first start conveying the subsequent sheet 25R, and then convey the subsequent sheet 25R by a distance (D+S) after the first inlet sensor 14 detects the leading edge of the subsequent sheet 25R.

[0039] As described above, according to the image forming apparatus 1 of this embodiment, when a jam occurs with the preceding sheet (jammed sheet 25J), the succeeding sheet 25R is conveyed to a position where it can be easily removed, so that the succeeding sheet 25R can be easily removed together with the jammed sheet 25J. Furthermore, since the jammed sheet 25J and the succeeding sheet 25R are located close to each other, it is possible to prevent forgetting to remove the succeeding sheet 25R.

[0040] Embodiment 2 FIG. 5 is a block diagram showing a configuration of a main part of a control system of image forming apparatus 2 according to the second embodiment of the present invention.

[0041] The main difference between the image forming apparatus 2 of the second embodiment equipped with this control system and the image forming apparatus 1 of the first embodiment equipped with the control system shown in Fig. 2 is the configuration of the jam control unit 220 (120 in the first embodiment). Therefore, the same reference numerals will be used to designate parts of the image forming apparatus 2 equipped with this control system that are common to the image forming apparatus 1 of the first embodiment, or the drawings will be omitted to omit the description, and the differences will be mainly described. Note that, apart from the above-mentioned points, the main configuration of the image forming apparatus 2 of this embodiment is common to the main configuration of the image forming apparatus 1 of the first embodiment shown in Fig. 1, and therefore Fig. 1 will be referred to as necessary.

[0042] In this embodiment, jam control unit 220 includes jam detection unit 107, paper detection unit 108, preceding / following paper transport feasibility determination unit 209 that determines whether jammed paper 25J and following paper 25R can be transported when a jam occurs, preceding / following transport amount calculation unit 210 that calculates the transport amount of jammed paper 25J and following paper 25R when a jam occurs, and preceding / following paper transport unit 211 as a transport control unit that transports based on this calculated transport amount. Note that preceding / following paper transport feasibility determination unit 209 and preceding / following transport amount calculation unit 210 correspond to a transport amount determination unit.

[0043] In the above configuration, jam response processing when a jam occurs in image forming apparatus 2 of this embodiment will be described with reference to Figures 6 and 7. Figure 6 is a flowchart showing the flow of jam response processing when a jam occurs, and Figure 7 is a diagram used to explain paper transport when a jam occurs, in which (a) shows the positions of jammed paper 25J and subsequent paper 25R before transport processing when the rear end of jammed paper 25J has not yet passed the distance S from the first registration roller pair 15, and (b) shows the state of jammed paper 25J and the position of subsequent paper 25R after transport processing.

[0044] In the flowchart of Fig. 6, the processes in steps S201 to S205 and steps S207 and S208 are exactly the same as the processes in steps S101 to S107 in the flowchart shown in Fig. 3 in embodiment 1. That is, as will be described later, if it is determined in step S206 that it can move to a position of distance S (step S206, Yes), image forming apparatus 2 in this embodiment performs exactly the same processes as the processes of image forming apparatus 1 described in embodiment 1, and therefore description thereof will be omitted here.

[0045] As described above, the position of the distance S downstream from the first registration roller pair 15 is visible to the user by opening the top cover 42 (FIG. 1), and is a guideline position where it is desirable that at least the leading edge of the succeeding sheet 25R has been transported in order to smoothly remove the succeeding sheet 25R. Therefore, in the image forming apparatus 2 of this embodiment, if the preceding jammed sheet 25J has not passed the guideline position of the distance S as shown in FIG. 7(a), the trailing edge of the jammed sheet 25J is first transported until it passes the distance S so that the preceding jammed sheet 25J and the succeeding sheet 25R do not overlap, and then, or simultaneously, the succeeding sheet 25R is transported so that the leading edge of the succeeding sheet 25R reaches the guideline position of the distance S.

[0046] That is, in the image forming apparatus 2 of this embodiment, in step S206, the preceding / following paper transport feasibility determination unit 209 determines whether the following paper 25R can move to the target position of distance S without overlapping with the preceding jammed paper 25J, for example, in the state shown in Figure 7(a), whether the rear end of the jammed paper 25J has passed the target position of distance S (step S206).

[0047] If the jammed sheet 25J has not completely passed through (No in step S206), the preceding / following conveyance amount calculation unit 210 calculates a conveyance distance Y until the rear end of the jammed sheet 25J passes the position of the distance S, and a conveyance distance S2 until the leading end of the following sheet 25R reaches the reference position of the distance S (step S209). The preceding / following sheet conveyance unit 211 drives only the second registration roller pair 17 to convey the trailing end of the jammed sheet 25J by the conveyance distance Y until the trailing end passes the reference position of the distance S, as shown in FIG. 7(b) (step S210), and thereafter or simultaneously with this conveyance, drives the registration intermediate roller pair 13 and the first registration roller pair 15 to convey the following sheet 25R by the conveyance distance S2 until the leading end of the following sheet 25R reaches the reference position of the distance S from the first registration roller pair 15, as shown in FIG. 7(b) (step S211).

[0048] Here, assuming that the distance from the vicinity of the leading edge of the succeeding sheet 25R to the first inlet sensor 14 is N, the distance from the first inlet sensor 14 to the first registration roller pair 15 is D, the distance from the first inlet sensor 14 to the vicinity of the rear edge of the jammed sheet 25J is X2, and the conveyance distance from the vicinity of the leading edge of the succeeding sheet 25R to the target position (a position at a distance S downstream from the first registration roller pair 15) is S2, the preceding / following conveyance amount calculation unit 210 calculates the conveyance distance S2 as S2=N+D+S The transport distance Y is calculated as follows: Y=D+S-X2 It is calculated by:

[0049] On the other hand, the preceding / following transport amount calculation unit 210 may calculate the transport distance (D+S) of the following sheet 25R. In this case, however, the preceding / following sheet transport unit 211 first starts transporting the following sheet 25R in step S211, and then transports the following sheet 25R by the transport distance (D+S) after the first inlet sensor 14 detects the leading edge of the following sheet 25R.

[0050] Furthermore, the leading edge position of the subsequent sheet 25R required to determine the distance N can be determined, for example, by calculating the distance the sheet is transported by the pair of resist intermediate rollers 13 from the time the leading edge of the subsequent sheet 25R passes the paper feed sensor 12 until the jam is detected, and the trailing edge position of the jammed sheet 25J required to determine the distance X2 can be determined, for example, by calculating the distance the sheet is transported by the first pair of resist rollers 15 from the time the jammed sheet 25J passes the first entrance sensor 14 until the jam is detected.

[0051] As described above, according to the image forming apparatus 2 of this embodiment, even if the jammed sheet 25J has not passed the target position of the distance S downstream from the first registration roller pair 15, the subsequent sheet 25R can be conveyed to this target position, so that when a jam occurs, it is possible to reliably remove the jammed sheet 25J and the subsequent sheet 25R, regardless of the timing of the jam. Also, because the jammed sheet 25J and the subsequent sheet 25R are close to each other, it is possible to prevent forgetting to remove the subsequent sheet 25R. [Industrial Applicability]

[0052] In the above embodiment, an example in which the present invention is applied to a monochrome printer is shown, but the present invention is not limited to this and can also be applied to image processing devices such as copiers, facsimiles, MFPs, etc. Also, although the present invention has been described with respect to a monochrome printer, it may also be applied to a color printer. [Explanation of symbols]

[0053] REFERENCE SIGNS LIST 1 image forming device, 2 image forming device, 10 paper tray, 11 medium feed roller, 12 paper feed sensor, 13 registration intermediate roller pair, 14 first entrance sensor, 15 first registration roller pair, 16 second entrance sensor, 17 second registration roller, 18 writing sensor, 19 image forming unit, 19a photosensitive drum, 19b transfer roller, 20 fixing unit, 20a heating roller, 20b pressure roller, 21 discharge sensor, 22 discharge roller pair, 23 discharge paper loading table, 24 paper transport path, 25 recording paper, 25J jammed paper, 25R subsequent paper, 41 bottom frame, 42 top cover, 43 rotating shaft, 101 system control unit, 102 connection I / F unit, 103 image data storage unit, 104 Print control unit, 105 media feed control unit, 106 media transport control unit, 107 jam detection unit, 108 paper detection unit, 109 transport possibility determination unit, 110 transport amount calculation unit, 111 subsequent paper transport unit, 112 fixing control unit, 113 operation / display unit, 114 memory unit, 115 print control data storage unit, 116 width setting information unit, 120 jam control unit, 207 jam detection unit, 209 preceding / subsequent paper transport possibility determination unit, 210 preceding / subsequent transport amount calculation unit, 211 preceding / subsequent paper transport unit, 220 jam control unit.

Claims

1. an image forming unit that forms an image on a sheet; a plurality of conveying rollers that convey the paper to the image forming unit; a jam detection unit that detects a jam of the paper; a paper detection unit that detects the paper using a first paper sensor that is arranged upstream of the image forming unit in the transport direction and a second paper sensor that is arranged downstream of the first paper sensor in the transport direction; a conveyance control unit that controls driving of the plurality of conveyance rollers; a transport distance determination unit that determines a transport distance of a subsequent sheet following the jammed sheet when the jammed sheet is detected by the second sheet sensor by the sheet detection unit; and the transport control unit controls the transport rollers to transport the subsequent sheet by a predetermined amount in the transport direction when the jam detection unit detects a jam of the sheet and the sheet detection unit detects the subsequent sheet by the first sheet sensor; If the second paper sensor does not detect the jammed paper, the subsequent paper is conveyed until the second paper sensor detects it; When the second paper sensor detects the jammed paper, the subsequent paper is conveyed based on the conveyance amount determined by the conveyance amount determination unit. An image forming apparatus characterized by:

2. The conveyance amount determined by the conveyance amount determination unit is determined based on the amount of conveyance of the succeeding sheet.

2. The method according to claim 1, wherein the distance is a distance for transporting the succeeding paper to the vicinity of the rear end of the paper. The image forming apparatus includes:

3. The image forming apparatus according to claim 1 or 2, characterized in that, if the jammed paper has not yet passed a predetermined target position, the transport control unit transports the trailing end of the jammed paper until it passes the predetermined target position, and then transports the subsequent paper to the predetermined target position.

Images