Image forming apparatus

Abstract

The system detects the paper on which the image is to be formed and performs the image formation operation. [Solution] An image forming apparatus comprising: a paper storage unit for storing paper; an image forming unit for forming an image on paper transported from the paper storage unit; a detection unit for detecting paper transported from the paper storage unit in a transport path just before the position where the image formed by the image forming unit is transferred to the transported paper; and a control unit for controlling the paper to be pre-transported from the paper storage unit to the position detected by the detection unit before the image is formed by the image forming unit.

Description

Technical Field

[0004] , , ,

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] In Patent Document 1, in an image forming apparatus including a medium storage unit that stores a medium, there are provided a paper feed control unit that feeds the medium stored in the medium storage unit, a detection unit that detects the remaining amount of the medium stored in the medium storage unit, and a search unit that searches for another medium storage unit that stores the same medium as the medium stored in the medium storage unit. When the detection unit, and when the detection unit detects that the remaining amount of the medium stored in the medium storage unit has reached a predetermined amount, the paper feed control unit feeds the medium stored in another medium storage unit searched by the search unit to a predetermined position. An image forming apparatus is disclosed. Further, in Patent Document 2, after laminating and transferring image information that has been color-separated into a plurality of pieces onto an intermediate transfer belt that contacts and rotates with a plurality of electrostatic latent image carriers at a predetermined pressure using a plurality of electrostatic latent image carriers, a paper feed method in an image forming apparatus using an intermediate transfer method in which a color image is formed on paper by collectively transferring the paper to the paper fed from the paper storage unit. When the number of printing required sheets is plural, the timing of performing a paper pickup step of feeding the paper from the paper storage unit one by one to the paper conveyance path is varied according to the number of sheets to be fed, and the presence or absence of the paper stored in the paper storage unit is detected. A paper feed method in an image forming apparatus is disclosed.

Prior Art Documents

Patent Documents

[0003] ​​​​​​​​​​​​​​​​​​An image forming apparatus is known that employs an intermediate transfer method in which an image is first transferred to an intermediate transfer medium, and then that image is transferred to the paper. In such an image forming apparatus, if the timing of image formation is earlier than the timing of paper feeding, a paper shortage will occur, and the image transferred to the intermediate transfer medium will not be transferred to the paper.

[0005] The present invention aims to detect the paper on which an image is to be formed and perform an image formation operation. [Means for solving the problem]

[0006] The invention described in claim 1 is an image forming apparatus comprising: a paper storage unit for storing paper; an image forming unit for forming an image on paper transported from the paper storage unit; a detection unit for detecting paper transported from the paper storage unit in a transport path prior to a position where the image formed by the image forming unit is transferred to the transported paper; and a control unit for controlling the paper to be pre-transported from the paper storage unit to a position detected by the detection unit before the image is formed by the image forming unit. The invention described in claim 2 is an image forming apparatus according to claim 1, characterized in that when the control unit receives an instruction to form an image and forms an image on multiple sheets of paper, it controls the second and subsequent sheets of paper to perform the pre-transportation before the image forming unit performs image forming. The invention described in claim 3 is an image forming apparatus according to claim 2, characterized in that the control unit controls the pre-transport of the second and subsequent sheets of paper so that the pre-transport is performed after the trailing edge of the preceding sheet has passed the detection unit. The invention described in claim 4 is an image forming apparatus according to claim 2, characterized in that the control unit controls the image forming unit to suppress image forming if it does not detect paper during the pre-transport. The invention described in claim 5 is an image forming apparatus according to claim 1, characterized in that the control unit controls the paper that has been pre-transported to a position detected by the detection unit to wait at the detected position until an opportunity arises to feed the paper to a position for transferring an image. The invention described in claim 6 is an image forming apparatus according to claim 5, characterized in that, if the paper feeding opportunity does not occur, the control unit controls the transport of the paper that has been pre-transported to a position detected by the detection unit to the paper storage unit. [Effects of the Invention]

[0007] According to the invention of claim 1, an image forming operation can be performed by detecting the paper on which the image is to be formed. According to the invention of claim 2, for the second and subsequent sheets of paper, the image formation operation can be performed by detecting the sheet on which an image is to be formed. According to the invention of claim 3, it is possible to prevent paper jams caused by overlapping sheets of paper. According to the invention of claim 4, it is possible to prevent the wasteful consumption of toner. According to the invention of claim 5, the productivity of image formation can be improved compared to the case where paper is fed from a paper tray. According to the invention of claim 6, it is possible to suppress false detection of paper jams caused by pre-transported paper. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the configuration of the image forming apparatus in this embodiment. [Figure 2] This is an explanatory diagram illustrating the paper feeding section in this embodiment. [Figure 3] This is a timing chart showing the operation of the image forming unit and paper feeding unit in a print job. [Figure 4] This is an explanatory diagram illustrating the pre-feeding of paper. [Figure 5] This flowchart shows the processing flow of a print job in this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0010] <Configuration of an image forming apparatus> Figure 1 shows an example of the configuration of the image forming apparatus 1 in this embodiment. The image forming apparatus 1 includes an image forming unit 10 inside its main body 1A that performs image formation based on image data. Furthermore, the image forming apparatus 1 includes a control unit 50 that controls the operation of each functional part of the image forming apparatus 1 and performs processing on image data. Furthermore, the image forming apparatus 1 is equipped with a user interface unit 80 that receives operation input from the user and displays various information to the user. Furthermore, the image forming apparatus 1 includes a paper feeding unit 30 that supplies paper to the image forming unit 10.

[0011] <Image Forming Section> The image forming unit 10 is a functional unit that forms images, for example, by an electrophotographic method. The image forming unit 10 comprises four image forming units: a yellow (Y) image forming unit 11Y, a magenta (M) image forming unit 11M, a cyan (C) image forming unit 11C, and a black (K) image forming unit 11K. The image forming units 11Y, 11M, 11C, and 11K form yellow toner images, magenta toner images, cyan toner images, and black toner images, respectively. Hereafter, when no distinction is made between the image forming units, they may be referred to as "image forming unit 11".

[0012] Each image forming unit 11 includes a photosensitive drum 12 as an example of an image holder. The photosensitive drum 12 is a rotating body formed in a cylindrical shape and rotating about the axial advance, and holds a toner image formed on the outer peripheral surface. In the present embodiment, an electrostatic latent image is formed on the surface of the photosensitive drum 12, and then development with toner is performed. As a result, a toner image is formed on the surface of the photosensitive drum 12, and this toner image is temporarily held by the photosensitive drum 12.

[0013] Each image forming unit 11 also includes a charging device 13 that charges the surface of the photosensitive drum 12. Each image forming unit 11 also includes an exposure device 14 that exposes the photosensitive drum 12 charged by the charging device 13 based on image data. Further, each image forming unit 11 includes a developing device 15 that develops the electrostatic latent image formed on the photosensitive drum 12 with toner of each color. Furthermore, each image forming unit 11 includes a cleaner 16 that cleans the surface of the photosensitive drum 12 after transfer. Note that each image forming unit 11 is configured in the same manner except for the toner housed in the developing device 15.

[0014] The image forming unit 10 also includes an intermediate transfer belt 70 to which the toner images of each color formed on the photosensitive drums 12 of the respective image forming units 11 are transferred. The image forming unit 10 also includes a primary transfer roll 71 that transfers (primary transfer) the toner images of each color formed in each image forming unit 11 to the intermediate transfer belt 70. Further, the image forming unit 10 includes a secondary transfer roll 72 that collectively transfers (secondary transfer) the toner images of each color transferred and superimposed on the intermediate transfer belt 70 to the paper. Furthermore, the image forming unit 10 includes a fixing device 60 that fixes the toner images of each color after secondary transfer onto the paper. In the present embodiment, the secondary transfer roll 72 is disposed, and the region where the toner images of each color on the intermediate transfer belt 70 are secondarily transferred to the paper is referred to as the secondary transfer region Tr.

[0015] <Control Unit> The control unit 50 consists of a memory that stores a program and a processor that executes the program stored in the memory. The memory stores data for execution, and the processor uses the data from the memory to perform various control and processing tasks.

[0016] <User Interface Section> The user interface unit 80 is composed of, for example, a display device such as a liquid crystal display and an operating device such as hardware keys or a touch sensor. The user interface unit 80 may also be configured as a touch panel combining a liquid crystal display and a touch sensor.

[0017] <Paper feed section> Figure 2 is an explanatory diagram illustrating the paper feeding unit 30 in this embodiment. The paper feeding unit 30 includes a first paper feeding tray 31A and a second paper feeding tray 31B, which are multiple paper feeding trays for accommodating standard paper sizes such as B5 and A4. Hereafter, when the first paper feed tray 31A and the second paper feed tray 31B are not distinguished, they may be referred to simply as the paper feed tray 31. The paper feed tray 31 is an example of a paper storage section. Furthermore, the paper feeding unit 30 is equipped with a feed roll 32 that feeds paper from the paper tray 31. The paper feeding unit 30 is also equipped with a paper transport path R for feeding paper to the image forming unit 10. In addition, the paper feeding unit 30 is equipped with detection sensors 33 to 35 that monitor the movement of the paper and detect jams.

[0018] In this embodiment, the detection sensor 33 is located on the paper transport path R and is provided at the boundary between the paper transport path R and the first paper feed tray 31A. It can also be said that the detection sensor 33 is located on the paper transport path R immediately after the first paper feed tray 31A. Furthermore, the detection sensor 34 is located on the paper transport path R, specifically at the boundary between the paper transport path R and the second paper tray 31B. It can also be said that the detection sensor 34 is located on the paper transport path R immediately following the second paper tray 31B. Furthermore, the detection sensor 35 is installed on the paper transport path R. The detection sensor 35 may be exemplified by detection sensor 35a, detection sensor 35b, detection sensor 35c, detection sensor 35d, etc. The detection sensor 35 may be provided at any location on the paper transport path R, before the secondary transfer area Tr. In this embodiment, the detection sensor 35 will be described using the case where it is detection sensor 35b as an example. Note that the number and position of detection sensors provided on the paper transport path R are examples only and are not limited to the number and position shown in Figure 2. The control of the paper feeding unit 30 in this embodiment will be described later.

[0019] <Operation of the image forming apparatus> Next, we will return to Figure 1 and explain the operation of the image forming apparatus 1. First, upon receiving a print job instruction, the image forming unit 10 has each of its image forming units 11 form toner images of black, cyan, magenta, and yellow through an electrophotographic process. Hereafter, this process (formation of toner images by charging, exposure, and development) may be referred to as the first step.

[0020] Next, the toner images of each color formed in each image forming unit 11 are sequentially transferred onto the intermediate transfer belt 70 by the primary transfer roll 71, and a toner image with each color toner superimposed is formed on the intermediate transfer belt 70. Hereinafter, this process (primary transfer) may be referred to as the second step. Also, the first and second steps together may be referred to as image formation. Next, the toner image on the intermediate transfer belt 70 is transported to the secondary transfer region Tr where the secondary transfer roll 72 is located, as the intermediate transfer belt 70 moves.

[0021] Meanwhile, in the paper feeding unit 30, a feed roll 32, which is an example of a transport member, feeds paper from the paper tray 31 to the paper transport path R. This fed paper is then transported along the paper transport path R by multiple transport rolls, which are also examples of transport members, and reaches the secondary transfer area Tr.

[0022] Subsequently, in the secondary transfer region Tr, the toner image on the intermediate transfer belt 70 is transferred to the paper all at once by the transfer electric field formed by the secondary transfer roll 72. Hereafter, this process (secondary transfer) may be referred to as the third step. The paper onto which the toner image has been transferred is then separated from the intermediate transfer belt 70 and transported along the paper transport path R to the fuser unit 60. The toner image on the paper transported to the fuser unit 60 is fixed to the paper by the fuser unit 60. After that, the paper is transported to the paper discharge unit 1B.

[0023] <Processing in the image forming section and paper feeding section> Figure 3 is a timing chart showing the operation of the image forming unit 10 and the paper feeding unit 30 in a print job. The horizontal axis represents time (t). Figure 4 is an explanatory diagram illustrating the pre-feeding of paper. Next, the operation of the image forming unit 10 and the paper feeding unit 30 during a print job in this embodiment will be described. This operation is achieved by the processor reading and executing a program stored in memory.

[0024] This section explains the case where the number of print jobs exceeds the number of sheets of paper stored in the paper tray 31. For example, consider a scenario where 2 sheets of paper are stored in the paper tray 31, and 3 print jobs are attempted. Furthermore, for this example, we will assume that paper is fed from the second paper tray 31B.

[0025] Upon receiving a print job, at time t1, the image forming unit 10 begins a series of processes for the first image, from the first to the second step (S101).

[0026] After the image forming unit 10 starts a series of processes from the first to the second step for the first image, when the paper feeding timing arrives at time t2, the paper feeding unit 30 feeds the first sheet of paper (S102). In this embodiment, "paper feeding" means transporting the paper to the secondary transfer area Tr. Furthermore, the timing for feeding the paper to the secondary transfer area Tr can be determined in various processes, such as the charging process, exposure process, development process, and primary transfer process. This feeding timing is determined by taking into account the transport speed of the paper and the speed at which the toner image is transported, so that the toner image on the intermediate transfer belt 70 is formed on the paper normally.

[0027] Subsequently, at time t3, the paper feed unit 30 performs an operation to pre-feed the second sheet of paper (S103). Here, "pre-transport" in this embodiment is different from paper feeding, which transports the paper to the secondary transfer area Tr. Pre-transport means that the paper transported from the paper feed tray 31 is transported to a predetermined position on the paper transport path R just before the secondary transfer area Tr, and then left to wait at that predetermined position. In other words, during pre-transport, the paper is transported to a predetermined position, but not to the secondary transfer area Tr. Furthermore, pre-transportation means transporting the paper being transported from the paper tray 31 to a predetermined position before the paper feeding timing occurs. For example, the predetermined position can be the position where the paper is detected by the detection sensor 33. Another example is that the predetermined position can be the position where the paper is detected by the detection sensor 34. Yet another example is that the predetermined position can be the position where the paper is detected by the detection sensor 35.

[0028] Figure 4 shows examples of how the paper is transported to predetermined positions, specifically an example where the paper is transported to detection sensor 33, an example where the paper is transported to detection sensor 34, and an example where the paper is transported to detection sensor 35. The predetermined positions are not limited to the detection sensors 33-35 that detect jams. The predetermined positions can be positions on the paper transport path R before the secondary transfer area Tr where paper is detected by a sensor with a paper detection function. Here, the predetermined position is described as the position where the paper is detected by the detection sensor 34. In step S103, the pre-feed operation for the second sheet of paper is performed only after it is detected that the trailing edge of the preceding sheet of paper has passed the detection sensor 34. Once the second sheet of paper has been pre-feeded, it waits in a position where it can be detected by the detection sensor 34 until the paper feeding timing arrives.

[0029] At time t4, the detection sensor 34 detects the second sheet of paper, and at time t5, the image forming unit 10 starts a series of processes from the first to the second step for the second image (S104).

[0030] After the image forming unit 10 starts a series of processes from the first to the second step for the second image, when the paper feeding timing arrives at time t6, the paper feeding unit 30 feeds the next sheet of paper, the second sheet (S105). In other words, the paper feeding unit 30 transports the next sheet of paper, the second sheet, which was waiting at the position detected by the detection sensor 34, to the secondary transfer area Tr.

[0031] Next, at time t7, the paper feed unit 30 performs an operation to pre-feed the next sheet of paper, the third sheet (S106). In this example, only two sheets of paper are stored in the second paper tray 31B, and it is not possible to pre-transport the third sheet of paper to the detection sensor 34. In this case, at time t8, the detection sensor 34 fails to detect the third sheet of paper, and as a result, it detects that the paper is out (S107).

[0032] When a paper shortage is detected, at time t9, the image forming unit 10 prevents the start of the series of processes from the first to the second for the third image, which is the next sheet of paper (S108).

[0033] Thus, in this embodiment, for the second and subsequent sheets of paper, pre-transportation of the paper is performed before the series of processing steps from the first to the second by the image forming unit 10. If a paper shortage is detected during this pre-transportation, the start of the series of processing steps from the first to the second by the image forming unit 10 is suppressed in advance. This suppresses contamination of the device and wasted toner consumption caused by image formation.

[0034] <Overall flow of a print job> Figure 5 is a flowchart showing the processing flow of a print job in this embodiment. In this embodiment, the processing of print jobs is achieved by the processor reading and executing a program stored in memory. Here, we will explain using the case where paper is fed from the second paper tray 31B as an example.

[0035] When a print job is received, the control unit 50 instructs the paper feed unit 30 to feed the first sheet of paper (S201). Next, the control unit 50 causes the paper feed unit 30 to pre-transport the next sheet of paper to a position where the paper is detected by the detection sensor 34 (S202). In S202, the next sheet of paper may be pre-transported to a detection sensor 35 located downstream of the detection sensor 34 in the paper transport direction.

[0036] Next, the control unit 50 checks whether the detection sensor 34 has detected paper (S203). If the detection sensor 34 does not detect paper (NO in S203), the control unit 50 determines that there is no paper and notifies the image forming unit 10 of this (S204). The control unit 50 then terminates the processing of the print job without allowing the image forming unit 10 to perform the series of processes from the first to the second step. Meanwhile, if the detection sensor 34 detects paper (YES in S203), the control unit 50 checks whether the job still requires paper feeding (S205).

[0037] If the control unit 50 confirms that the job still requires paper feeding (YES in S205), it will feed the paper that has been pre-transported to the detection sensor 34 at the paper feeding timing (S206). After that, it returns to S202.

[0038] On the other hand, if the control unit 50 confirms that paper feeding is not required for the job (NO in S205), it executes a process to return the paper that has been pre-transported to the detection sensor 34 to the second paper feed tray 31B (S207), and terminates the processing of the print job. In this case, the transport roll and feed roll 32, which are examples of transport members, rotate in reverse while in contact with the pre-transported paper, thereby pulling the pre-transported paper back into the second paper feed tray 31B. As a result, if there is no opportunity to feed paper, such as when a print job is completed or a malfunction occurs in the device, the pre-transported paper is placed back into the paper tray 31.

[0039] <Control to suppress false jam detection> Next, we will explain the control mechanism for suppressing false jam detections. In this embodiment, a detection sensor used to detect jams is used to detect pre-transported paper. Therefore, this embodiment incorporates control to suppress false jam detections caused by pre-transported paper.

[0040] There are two types of jam detection: dynamic jams and static jams. Dynamic jam detection is used to detect paper jams or delays in paper transport during transit. Generally, dynamic jam detection is performed using methods such as detecting a jam if the sensor fails to detect paper within a predetermined time after a jam monitoring trigger event (e.g., paper feed timing) occurs. In this embodiment, if a paper feeding timing (jam monitoring trigger event) occurs for pre-transported paper, the detection sensor that has already detected the pre-transport of paper will skip jam detection. Then, the next detection sensor, which is installed downstream of the detection sensor that has already detected the pre-transport of paper, will detect the jam.

[0041] Here, as an example, we consider the case where paper from the paper feed tray 31B is pre-transported to the detection sensor 34. Furthermore, the jam detection time for the detection sensor 34 is set to, for example, 100 milliseconds after the paper feed timing (jam monitoring trigger event). Also, the jam detection time for the detection sensor 35 located downstream of the detection sensor 34 is set to, for example, 500 milliseconds after the paper feed timing (jam monitoring trigger event).

[0042] In this embodiment, when the first sheet of paper is fed, the detection sensor 34 monitors whether or not it detects the paper for 100 milliseconds after the paper feeding timing occurs to detect a jam. Additionally, the detection sensor 35 monitors whether or not it detects the paper for 500 milliseconds after the paper feeding timing occurs to detect a jam.

[0043] On the other hand, if a paper feeding timing occurs for the second or subsequent sheets of paper that have been pre-transported to the detection sensor 34, the detection sensor 34 will skip monitoring for jams. For the pre-fed paper, the detection sensor 35 monitors whether it detects the paper for 400 milliseconds after the paper feeding timing occurs, and performs jam detection. This 400 milliseconds is calculated by subtracting the jam detection time of the detection sensor 34 (100 milliseconds) from the jam detection time of the detection sensor 35 (500 milliseconds), taking into account that the paper has been pre-fed to the detection sensor 34. For pre-fed paper, if the detection sensor 35 does not detect the paper within a predetermined time (400 milliseconds) from the paper feeding timing, a jam is detected. This ensures that jam detection is not suppressed even when pre-fed, and false detections due to pre-fed paper are also suppressed.

[0044] Static jam detection involves detecting residual paper on the paper transport path R. Jam detection timings include, for example, when the power is turned on, when printing is completed, and when the device door or cover is opened or closed. In this embodiment, pre-transported paper is returned to the paper tray 31 if no opportunity to feed paper arises, as described above. If pre-transported paper remains on the paper transport path R due to certain factors, the paper on the paper transport path R is detected by a detection sensor at jam detection timings such as when the power is turned on, when printing is completed, or when the device door or cover is opened or closed, and a jam is detected. Therefore, static jam detection is not suppressed, and no special control is needed to suppress false detections.

[0045] Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above embodiments. In this embodiment, the second and subsequent sheets of paper are pre-fed, but the invention is not limited to this. The first sheet of paper may be pre-fed, and after detection by the detection sensor, the series of processes from the first to the second step by the image forming unit 10 may be started.

[0046] Furthermore, although this embodiment has been described using the case where the detection sensor 35 is detection sensor 35b as an example, the detection sensor 35 may be, for example, detection sensor 35a. Here, we consider the case where the detection sensor 35a is positioned such that the distance from the detection sensor 35a to the secondary transfer area Tr is the same as the distance from the detection sensor 33 to the secondary transfer area Tr. In this case, the distance to the secondary transfer area Tr is the same for the paper that has been pre-transported to the detection sensor 33 and the paper that has been pre-transported to the detection sensor 35a. This allows the paper transport speed during paper feeding to be controlled identically, whether the paper is pre-transported from the first paper tray 31A to the detection sensor 33 or from the second paper tray 31B to the detection sensor 35a. Furthermore, various modifications and configuration substitutions that do not depart from the technical concept of the present invention are included within the scope of this invention.

[0047] <Note> (((1))) An image forming apparatus comprising: a paper storage unit for storing paper; an image forming unit for forming an image on paper transported from the paper storage unit; a detection unit for detecting paper transported from the paper storage unit in a transport path prior to a position where the image formed by the image forming unit is transferred to the transported paper; and a control unit for controlling the paper to be pre-transported from the paper storage unit to a position detected by the detection unit before the image is formed by the image forming unit. (((2))) The image forming apparatus according to (((1))), characterized in that when the control unit receives an instruction to form an image and forms an image on multiple sheets of paper, it controls the pre-transport of the second and subsequent sheets of paper before the image forming unit performs image forming. (((3))) The image forming apparatus according to (((1))) or (((2))), characterized in that the control unit controls the pre-transport of the second and subsequent sheets of paper so that the pre-transport is performed after the trailing edge of the preceding sheet has passed the detection unit. (((4))) The image forming apparatus according to any one of (((1))) to (((3))), characterized in that the control unit controls the image forming unit to suppress image formation if it does not detect paper during the pre-transport. (((5))) The image forming apparatus according to any one of (((1))) to (((4))), characterized in that the control unit controls the paper that has been transported to a position detected by the detection unit to wait at the detected position until an opportunity arises to feed the paper to a position in which an image is transferred. (((6))) The image forming apparatus according to any one of (((1))) to (((5))), characterized in that, if the paper feeding opportunity does not occur, the control unit controls the transport of the paper that has been transported to the position detected by the detection unit to the paper storage unit.

[0048] According to the invention of (((1))), an image forming operation can be performed by detecting the paper on which an image is formed. According to the invention of (((2))), for the second and subsequent sheets of paper, the paper on which an image is to be formed can be detected and the image forming operation can be performed. According to the invention of (((3))), it is possible to prevent paper jams caused by overlapping sheets of paper. According to the invention of (((4))), it is possible to prevent the wasteful consumption of toner. According to the invention of (((5))), the productivity of image formation can be improved compared to feeding paper from a paper tray. According to the invention of (((6))), false detection of paper jams caused by pre-transported paper can be suppressed. [Explanation of Symbols]

[0049] 1…Image forming apparatus, 10…Image forming section, 11…Image forming unit, 12…Photoreceptor drum, 13…Charging device, 14…Exposure device, 15…Developing device, 16…Cleaner, 30…Paper feeding section, 31…Paper feeding tray, 32…Feeding roll, 50…Control unit, 60…Fusing device, 70…Intermediate transfer belt, 71…Primary transfer roll, 72…Secondary transfer roll, 80…User interface section

Claims

1. A paper storage section for storing paper, An image forming unit that forms an image on paper transported from the aforementioned paper storage unit, A detection unit detects the paper being transported from the paper storage unit in the transport path just before the position where the image formed by the image forming unit is transferred to the transported paper, Before the image is formed in the image forming unit, a control unit controls the paper to be pre-transported from the paper storage unit to a position detected by the detection unit. An image forming apparatus having

2. The control unit, upon receiving an instruction to form an image on multiple sheets of paper, controls the pre-transportation of the second and subsequent sheets of paper before the image forming unit performs image formation. The image forming apparatus according to claim 1, characterized by the following:

3. The control unit controls the pre-feeding of the second and subsequent sheets of paper so that the pre-feeding is performed after the trailing edge of the preceding sheet of paper has passed the detection unit. The image forming apparatus according to claim 2, characterized by the following:

4. The control unit controls the image forming unit to suppress image formation if it does not detect paper during the pre-transport process. The image forming apparatus according to claim 2, characterized by the following:

5. The control unit controls the paper to wait at the position detected by the detection unit until a paper feeding opportunity arises in which the paper is fed to the position where the image is transferred. The image forming apparatus according to claim 1, characterized by the following:

6. The control unit, if the paper feeding opportunity does not occur, controls the transport of the paper that has been transported to the position detected by the detection unit to the paper storage unit. The image forming apparatus according to claim 5, characterized by the following:

Images