Image forming apparatus, conveying method, and program

Abstract

To provide an image forming apparatus, a conveying method, and a program capable of reducing the occurrence of damage when correcting the inclination of thin printing paper with weak stiffness. [Solution] The system comprises a detection unit that detects the inclination of the printing paper based on detection information from a sensor that detects the printing paper and is arranged in the transport path, and a transport control unit that drives a transport roller arranged upstream of the registration roller in the transport path of the printing paper to press the printing paper against the registration roller while the registration roller that transports the printing paper to the image forming unit is stopped rotating, and after the transport control unit presses the printing paper against the registration roller, controls the reverse movement of the registration roller and the pushing operation of the transport roller to press the printing paper against the registration roller based on the inclination detected by the detection unit and information about the printing paper.

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a conveying method, and a program. [Background technology]

[0002] 2. Description of the Related Art In image forming apparatuses, a technique is known in which the printing paper is abutted against registration rollers to create slack and tuck the printing paper into a roller nip, thereby correcting the skew of the printing paper.

[0003] As a technique for correcting such skew of printing paper, a configuration has been disclosed in which a roller upstream of the registration roller is driven in the conveyance direction while slack is being formed by the registration roller to maintain the amount of slack (for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technique described in Patent Document 1 has a problem in that the above operation may damage thin printing paper that is weak in stiffness.

[0005] The present invention has been made in consideration of the above, and aims to provide an image forming apparatus, a conveying method, and a program that can reduce the occurrence of damage when correcting the skew, even for thin printing paper with weak stiffness. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present invention comprises a detection unit that detects the skew of the printing paper based on detection information from a sensor that is arranged in the transport path and detects the printing paper, and a transport control unit that drives a transport roller that is arranged upstream of the registration roller in the transport path of the printing paper while the registration roller that transports the printing paper to the image forming unit is stopped rotating, to press the printing paper against the registration roller, and is characterized in that after the printing paper is pressed against the registration roller, the transport control unit controls the reverse operation of the registration roller and the pushing operation of the printing paper by the transport roller based on the skew detected by the detection unit and information about the printing paper. [Effects of the Invention]

[0007] According to the present invention, even thin printing paper with low stiffness can be reduced in occurrence of damage when correcting skew. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an image forming apparatus according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an operation of generating slack in the image forming apparatus according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of the image forming apparatus according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the functional block configuration of the image forming apparatus according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing an example of the flow of the tilt correction operation of the image forming apparatus according to the first embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of the flow of the tilt correction operation of the image forming apparatus according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of an image forming apparatus, a conveying method, and a program according to the present invention will be described in detail with reference to the drawings. Furthermore, the present invention is not limited to the following embodiments, and the components in the following embodiments include those that can be easily conceived by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, various omissions, substitutions, modifications, and combinations of the components can be made without departing from the spirit of the following embodiments.

[0010] [First embodiment] (Configuration and Operation Overview of Image Forming Device) Fig. 1 is a diagram showing an example of the configuration of an image forming apparatus according to the first embodiment. Fig. 2 is a diagram illustrating an operation of generating slack in the image forming apparatus according to the first embodiment. The configuration and operation of the image forming apparatus 10 according to this embodiment will be described with reference to Figs. 1 and 2.

[0011] As shown in FIG. 1, the image forming apparatus 10 is, for example, a tandem-type printing apparatus, and includes a paper feed tray 700, a registration roller 701, an intermediate transfer belt 702, photosensitive drums 703C, 703M, 703Y, and 703K, a transfer roller 704, a fixing roller 705, a reversing roller 706, a double-sided paper feed roller 707, a conveying roller 708, a conveying roller 709, and a non-contact sensor 710.

[0012] The paper feed tray 700 is a tray that stores printing paper, which is a recording medium to be fed.

[0013] The registration rollers 701 are rollers that temporarily stop the printing paper conveyed from the conveying rollers 709 and send it to the transfer rollers 704 in synchronization with the intermediate transfer image moving on the intermediate transfer belt 702 .

[0014] The intermediate transfer belt 702 is an endless belt on which an intermediate transfer image is formed by photosensitive drums 703C, 703M, 703Y, and 703K.

[0015] Photoconductor drum 703C is a photoconductor drum that forms a cyan toner image on intermediate transfer belt 702. Photoconductor drum 703M is a photoconductor drum that forms a magenta toner image on intermediate transfer belt 702. Photoconductor drum 703Y is a photoconductor drum that forms a yellow toner image on intermediate transfer belt 702. Photoconductor drum 703K is a photoconductor drum that forms a black toner image on intermediate transfer belt 702. Note that photoconductor drums 703C, 703M, 703Y, and 703K will be simply referred to as "photoconductor drum 703" when referring to any one of the photoconductor drums or when referring to them collectively.

[0016] The transfer roller 704 is a roller that transfers a full-color image or a monochrome image (intermediate transfer image) formed on the intermediate transfer belt 702 onto the printing paper conveyed by the registration roller 701. By the function of this transfer roller 704, a full-color or monochrome image is formed (printed) on the recording medium.

[0017] The fixing roller 705 is a roller for fixing a full-color image onto the printing paper on which the image has been formed.

[0018] The reversing rollers 706 are rollers for reversing the print paper in the conveying path after an image has been formed on the front side of the print paper when double-sided printing is performed. The reversing rollers 706 then send the reversed print paper to the return path.

[0019] The double-sided paper feed roller 707 is disposed on the return path and sends the printing paper that has been turned over by the reversing roller 706 to the transport roller 708 again.

[0020] The transport roller 708 is a roller that transports the printing paper fed from the paper feed tray 700 to the transport roller 709 along the transport path.

[0021] The non-contact sensor 710 is disposed upstream of the registration rollers 701 and is a sensor that detects the print paper being transported along the transport path in order to detect the inclination (skew) of the print paper relative to the transport path. The non-contact sensor 710 is an example of the "sensor" of the present invention.

[0022] The conveying roller 709 is a roller that sends the printing paper sent out from the conveying roller 708 toward the registration roller 701 .

[0023] Print paper sent from paper feed tray 700 to the transport path may become tilted relative to the transport path during transport. If an image is transferred to the print paper by transfer roller 704 in this state, the image will be misaligned relative to the print paper, and it will be necessary to correct the tilt of the print paper.

[0024] In this case, the transport rollers 709 transport the printing paper P as shown in FIG. 2(a), and abut the printing paper P against the registration rollers 701, which are stopped from rotating as shown in FIG. 2(b). Furthermore, while the printing paper P is abutting against the registration rollers 701, the transport rollers 709 press the printing paper P against the registration rollers 701 by a predetermined amount (or for a predetermined time), thereby causing slack in the printing paper P as shown in FIG. 2(c). This corrects any skew that occurred during the transportation process of the printing paper P. Then, by driving the registration rollers 701, the printing paper, whose skew has been corrected, is transported to the transfer rollers 704.

[0025] However, after skew correction of the print sheet P, when the registration rollers 701 are driven to transport the print sheet P to the transfer rollers 704, the slack may not be maintained depending on the stiffness of the print sheet P, resulting in the expected skew correction effect being unsuccessful. To prevent this, for example, a method can be considered in which the registration rollers 701 are rotated in reverse just before resuming transport of the print sheet P that has stopped at the registration rollers 701, and the transport rollers 709 upstream of the registration rollers 701 are rotated in forward direction, thereby maintaining the slack in the print sheet P and restarting transport. However, with this method, if the print sheet P is thin paper with low stiffness, excessive slack may be created, potentially damaging the print sheet P. Therefore, in this embodiment, the actual amount of skew of the print sheet P is detected using detection information from the non-contact sensor 710, and the pushing and reversing operations for the print sheet P are controlled to reduce damage even to thin paper with low stiffness. Details of the skew correction operation of the image forming apparatus 10 according to this embodiment will be described later.

[0026] The image forming apparatus 10 is equipped with various sensors (not shown) for detecting how far the print paper has been transported inside the apparatus.

[0027] (Hardware configuration of image forming device) 3 is a diagram showing an example of the hardware configuration of the image forming apparatus according to the first embodiment. The hardware configuration of the image forming apparatus 10 according to this embodiment will be described with reference to FIG.

[0028] As shown in FIG. 3, the image forming apparatus 10 includes a controller 11, an image forming unit 12, various rollers (various rollers shown in FIG. 1), and various sensors (various sensors including a non-contact sensor 710).

[0029] The controller 11 is a control device that controls the image forming apparatus 10. As shown in Fig. 3 , the controller 11 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, an engine interface 504, a sensor interface 505, a storage device 506, a DFE (Digital Front End) interface 507, and a drive circuit 508.

[0030] The CPU 501 is a computing device that controls the overall operation of the image forming apparatus 10. The ROM 502 is a non-volatile storage device that stores programs for the image forming apparatus 10. The RAM 503 is a volatile storage device that is used as a work area for the CPU 501.

[0031] The engine interface 504 is an interface for data communication to control the image forming unit 12 .

[0032] The sensor interface 505 is an interface for receiving detection signals from various sensors in the image forming apparatus 10 (various sensors including the non-contact sensor 710).

[0033] The storage device 506 is a storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores various data, programs, and the like.

[0034] The DFE interface 507 is an interface for data communication with the DFE 20. The DFE 20 is an information processing device (image processing device) that performs RIP (Raster Image Processor) processing and the like to convert submitted print data into a format compatible with print processing in the image forming device 10.

[0035] The drive circuit 508 is a drive circuit for driving various rollers in the image forming apparatus 10 shown in FIG.

[0036] The above-mentioned CPU 501, ROM 502, RAM 503, engine interface 504, sensor interface 505, storage device 506, DFE interface 507 and drive circuit 508 are communicatively connected to one another by a bus 510 such as an address bus and a data bus.

[0037] The image forming unit 12 is a mechanism for forming a full-color image or a monochrome image on a recording medium. The image forming unit 12 corresponds to, for example, the intermediate transfer belt 702, the photosensitive drum 703, and the transfer roller 704 shown in FIG.

[0038] The hardware configuration of the image forming apparatus 10 shown in FIG. 3 is an example, and it is not necessary to include all of the components shown in FIG. 3, or other components may be included.

[0039] (Configuration and operation of functional blocks of image forming apparatus) 4 is a diagram showing an example of the configuration of functional blocks of the image forming apparatus according to the first embodiment. The configuration and operation of the functional blocks of the image forming apparatus 10 according to this embodiment will be described with reference to FIG.

[0040] The controller 11 of the image forming apparatus 10 includes a paper position detection unit 101, a tilt detection unit 102 (detection unit), a transport control unit 103, a print control unit 104, and a storage unit 105, as shown in FIG.

[0041] The paper position detection unit 101 is a functional unit that receives detection information detected by various sensors arranged on the transport path of the printing paper within the image forming device 10 via the sensor interface 505, and detects the position of the printing paper within the image forming device 10 based on the detection information.

[0042] The skew detection unit 102 is a functional unit that receives detection information detected by the non-contact sensor 710 via the sensor interface 505 and, based on the detection information, detects the skew of the print paper relative to the transport path as it is transported from the transport rollers 709 to the registration rollers 701. Note that, as long as the skew can be detected by the skew detection unit 102, another sensor may be used instead of the non-contact sensor 710.

[0043] The transport control unit 103 is a functional unit that controls various rollers in the image forming apparatus 10, such as the transport rollers 708, transport rollers 709, and registration rollers 701, via the drive circuit 508, and controls the transport of printing paper.

[0044] The print control unit 104 is a functional unit that controls the image forming unit 12 and controls the printing operation on the printing paper conveyed by the registration rollers 701 .

[0045] The storage unit 105 is a functional unit that stores various types of information. The storage unit 105 stores, as printing information, the number of copies to be printed, the number of sheets per copy, the paper type, paper thickness, and paper size, etc., included in a print job received from the DFE 20 via the DFE interface 507. The storage unit 105 also stores, as slack formation information, various types of information used to form slack in the print paper in order to correct the skew of the print paper as described above (for example, various thresholds for determining thresholds for skew and paper thickness, the amount of pressure applied by the conveyance rollers 709 to form slack, and the amount of reverse rotation of the registration rollers 701). The storage unit 105 is realized by the RAM 503 or the storage device 506 shown in FIG. 3.

[0046] The above-described paper position detection unit 101, skew detection unit 102, transport control unit 103, and print control unit 104 are realized by executing a program by CPU 501 shown in Fig. 3. Note that at least a part of the functional units among paper position detection unit 101, skew detection unit 102, transport control unit 103, and print control unit 104 that are realized by software (programs) may be realized by hardware circuits such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0047] Note that the functional units of the controller 11 shown in Fig. 4 are conceptual representations of functions, and are not limited to such configurations. For example, the multiple functional units illustrated as independent functional units in the controller 11 shown in Fig. 4 may be configured as a single functional unit. On the other hand, the function of a single functional unit in the controller 11 shown in Fig. 4 may be divided into multiple units and configured as multiple functional units. Furthermore, the functional units of the controller 11 do not need to be configured as distinct software modules as shown in Fig. 4, and it is sufficient that the functions of the functional units as a whole are realized by executing a program in the controller 11.

[0048] (Flow of tilt correction operation of image forming device) 5 is a flowchart showing an example of the flow of the tilt correction operation of the image forming apparatus 10 according to the first embodiment. The flow of the tilt correction operation of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG.

[0049] <Step S11> When the print control unit 104 of the controller 11 receives a print job from, for example, the DFE 20, it stores the number of copies, number of sheets per copy, paper type, paper thickness, paper size, and other information included in the print job as print information in the storage unit 105. Then, the process proceeds to step S12.

[0050] <Step S12> The transport control unit 103 of the controller 11 drives the transport rollers 709 to cause the print paper P to abut against the registration rollers 701, which are stopped from rotating. The skew detection unit 102 of the controller 11 receives detection information detected by the non-contact sensor 710 with respect to the transported print paper via the sensor interface 505, and based on that detection information, detects the skew of the print paper when it abuts against the registration rollers 701 from the transport rollers 709. Then, the process proceeds to step S13.

[0051] <Step S13> The conveyance control unit 103 of the controller 11 determines whether the skew of the print paper detected by the skew detection unit 102 is equal to or greater than a predetermined threshold (first threshold). For example, the predetermined threshold may be stored as slack formation information in the memory unit 105, and the conveyance control unit 103 may make the above determination based on the predetermined threshold by referring to the slack formation information in the memory unit 105. If the skew is equal to or greater than the predetermined threshold (step S13: Yes), the process proceeds to step S14, and if it is less than the predetermined threshold (step S13: No), the process proceeds to step S16.

[0052] In addition, if the inclination of the printing paper detected by the inclination detection unit 102 exceeds a predetermined upper limit value, the conveyance control unit 103 may stop operation and notify the DFE 20 or the like of an abnormality, assuming that the inclination cannot be corrected.

[0053] <Step S14> Furthermore, the conveyance control unit 103 determines whether the paper thickness (thickness of the print paper P) included in the printing information stored in the memory unit 105 is equal to or greater than a predetermined threshold (second threshold). For example, the predetermined threshold may be stored in the memory unit 105 as slack formation information, and the conveyance control unit 103 may refer to the slack formation information in the memory unit 105 and make the above determination based on the predetermined threshold. If the paper thickness is equal to or greater than the predetermined threshold (step S14: Yes), the process proceeds to step S15, and if it is less than the predetermined threshold (step S14: No), the process proceeds to step S16. The paper thickness in this case is an example of "information related to the print paper" in the present invention.

[0054] The order of the determination operations in steps S13 and S14 may be reversed.

[0055] <Step S15> If the skew of the print paper is equal to or greater than a predetermined threshold and the paper thickness is equal to or greater than a predetermined threshold (i.e., the print paper is not thin paper), the conveyance control unit 103 reverses the registration rollers 701 and pushes the print paper against the registration rollers 701 by a predetermined amount (or for a predetermined time) using the conveyance rollers 709, which are upstream rollers of the registration rollers 701. For example, the reversal amount of the reversal operation and the predetermined amount of the pushing operation may be stored in the memory unit 105 as slack formation information, and the conveyance control unit 103 may perform the reversal operation and the pushing operation by referring to the slack formation information in the memory unit 105. This corrects the skew of the print paper. In this case, since the print paper is not thin paper, it will not be damaged by the reversal operation and the pushing operation. Thereafter, the conveyance control unit 103 rotates the registration rollers 701 forward at the appropriate timing to convey the print paper to the transfer rollers 704 (image forming unit 12).

[0056] <Step S16> If the skew of the printing paper is less than a predetermined threshold or the paper thickness is less than a predetermined threshold (i.e., the paper is thin), the conveyance control unit 103 does not perform the pushing operation by the conveyance rollers 709, but only performs the reverse operation of the registration rollers 701. This is because, when the skew of the printing paper is less than the predetermined threshold, the skew can be corrected by the reverse operation of the registration rollers 701 alone, without the pushing operation by the conveyance rollers 709. Also, when the thickness of the printing paper is less than the predetermined threshold (i.e., the paper is thin), if the conveyance rollers 709 push the registration rollers 701, the amount of slack increases, which could cause damage, so only the reverse operation of the registration rollers 701 is performed. For example, the amount of reversal of the reverse operation described above may be stored in the memory unit 105 as slack formation information, and the conveyance control unit 103 may perform the reverse operation described above by referring to the slack formation information in the memory unit 105. Thereafter, the conveyance control unit 103 rotates the registration rollers 701 in the normal direction at an appropriate timing to convey the printing paper to the transfer rollers 704 (image forming unit 12).

[0057] Furthermore, even if the thickness of the printing paper is less than a predetermined threshold (i.e., if it is thin paper), if it is known in advance how much pressure the conveying roller 709 should apply to avoid damaging the printing paper, the conveying roller 709 may press the printing paper to that amount.

[0058] Through the above steps S11 to S16, the tilt correction operation of the image forming apparatus 10 is performed.

[0059] As described above, in image forming apparatus 10 according to this embodiment, skew detection unit 102 detects the skew of a print sheet based on detection information from non-contact sensor 710, which is arranged in the transport path and detects the print sheet, and transport control unit 103, while registration roller 701, which transports the print sheet to image forming unit 12 (transfer roller 704), is stopped, drives transport roller 709, which is arranged upstream of registration roller 701 in the transport path of the print sheet, to abut the print sheet against registration roller 701. After the print sheet abuts against registration roller 701, it controls the reverse movement of registration roller 701 and the pushing operation of transport roller 709 to push the print sheet forward based on the skew detected by skew detection unit 102 and information about the print sheet (such as paper thickness). This makes it possible to reduce damage to thin, stiff print paper when correcting for skew.

[0060] Furthermore, in the image forming apparatus 10 according to this embodiment, the conveyance control unit 103 determines whether the thickness of the print paper is equal to or greater than a predetermined threshold, and if the paper thickness is less than the predetermined threshold, the conveyance rollers 709 do not push the paper, but instead the registration rollers 701 rotate in the reverse direction. This makes it possible to prevent damage to the print paper caused by excessive sagging when the print paper is thin paper.

[0061] [Second embodiment] The image forming apparatus 10 according to the second embodiment will be described, focusing on the differences from the image forming apparatus 10 according to the first embodiment. Note that the overall configuration, hardware configuration, and functional block configuration of the image forming apparatus 10 according to this embodiment are the same as those described in the first embodiment.

[0062] (Determining the amount of pressure) The storage unit 105 stores, as slack formation information, information (hereinafter sometimes simply referred to as association information) that indicates the association between the thickness and length of the print paper and the amount of pressurization of the print paper by the conveyance rollers 709 against the registration rollers 701, as shown in Table 1 below. The paper length corresponds, for example, to the number of roller nips. The association information shown in Table 1 was experimentally determined in advance based on the thickness and size (including paper length) of the print paper to determine the amount of pressurization of the print paper by the conveyance rollers 709 that will create the optimal slack. For example, if the paper length is "long" and the paper thickness is "thin," the pressurization amount that creates the optimal slack is "small." Note that Table 1 classifies the pressurization amounts as "small," "medium," and "large," but this is not limiting and more detailed classifications may be used. Furthermore, the pressurization amounts may be further classified and associated with the paper thickness and paper length.

[0063] [Table 1]

[0064] The conveyance control unit 103 refers to the association information in the storage unit 105 and determines the pressing amount associated with the association information from the paper thickness and paper size (including paper length) of the print information corresponding to the print job.

[0065] Note that the association information shown in Table 1 is information on the amount of pressing associated with paper thickness and paper length, but is not limited to this. For example, since the amount of slack in printing paper can vary depending on the Y / T thread, the association information may associate paper type with the amount of pressing in addition to, or instead of, paper thickness and paper length. Also, the skew of printing paper detected by the skew detection unit 102 may be information on the amount of pressing in addition to, or instead of, paper thickness, paper length, and paper type. The above-mentioned paper thickness, paper length, and paper type are examples of "information related to printing paper" in this invention.

[0066] (Flow of tilt correction operation of image forming device) 6 is a flowchart showing an example of the flow of the tilt correction operation of the image forming apparatus 10 according to the second embodiment. The flow of the tilt correction operation of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG.

[0067] <Step S21> For example, when the print control unit 104 of the controller 11 receives a print job from the DFE 20, it stores the number of copies, number of sheets per copy, paper type, paper thickness, paper size, and other information included in the print job as print information in the storage unit 105. Then, the process proceeds to step S22.

[0068] <Step S22> The transport control unit 103 of the controller 11 drives the transport rollers 709 to cause the print paper P to abut against the registration rollers 701, which are stopped from rotating. The skew detection unit 102 of the controller 11 receives detection information detected by the non-contact sensor 710 with respect to the transported print paper via the sensor interface 505, and based on that detection information, detects the skew of the print paper when it abuts against the registration rollers 701 from the transport rollers 709. Then, the process proceeds to step S23.

[0069] <Step S23> The conveyance control unit 103 refers to the association information in the storage unit 105 and determines the push-in amount associated with the paper thickness and paper length included in the printing information in the storage unit 105 by the association information as the push-in amount to be used in the print paper push-in operation by the conveyance rollers 709. Then, the process proceeds to step S24.

[0070] <Step S24> The conveyance control unit 103 reverses the registration rollers 701 and causes the conveyance rollers 709, which are rollers upstream of the registration rollers 701, to press the print paper against the registration rollers 701 by the determined pressing amount. The reversal amount of the reverse rotation is stored in the memory unit 105 as slack formation information, and the conveyance control unit 103 may refer to the slack formation information in the memory unit 105 to perform the reversing and pressing operations. This corrects any skew that occurs in the print paper. Thereafter, the conveyance control unit 103 rotates the registration rollers 701 forward at an appropriate timing to convey the print paper to the transfer rollers 704 (image forming unit 12).

[0071] Through the above steps S21 to S24, the tilt correction operation of the image forming apparatus 10 is performed.

[0072] As described above, in the image forming apparatus 10 according to this embodiment, the storage unit 105 stores association information that associates at least the skew of the print paper with the pushing amount of the pushing operation by the conveyance rollers 709, and the conveyance control unit 103 determines the pushing amount associated with the skew detected by the skew detection unit 102 using the association information, and causes the conveyance rollers 709 to push the print paper against the registration rollers 701 by the determined pushing amount. This makes it possible to reduce damage when correcting skew, even for thin print paper with low stiffness.

[0073] In each of the above-described embodiments, when at least one of the functional units of the controller 11 is realized by executing a program, the program is provided by being pre-installed in a ROM or the like. Furthermore, in each of the above-described embodiments, the program executed by the controller 11 may be provided by being recorded in an installable or executable file format on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disc). Furthermore, in each of the above-described embodiments, the program executed by the controller 11 may be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Furthermore, in each of the above-described embodiments, the program executed by the controller 11 may be provided or distributed via a network such as the Internet. Furthermore, in each of the above-described embodiments, the program executed by the controller 11 has a modular configuration including at least one of the above-described functional units. In terms of actual hardware, the CPU 501 reads and executes the program from the above-described storage device (e.g., the ROM 502, the storage device 506, etc.), thereby loading and generating the above-described functional units into the main storage device (RAM 503).

[0074] The aspects of the present invention are as follows. <1> a detection unit that detects the inclination of the printing paper based on detection information from a sensor that detects the printing paper, the sensor being disposed on the conveyance path; a conveyance control unit that, while a registration roller that conveys the print paper to an image forming unit is stopped from rotating, drives a conveyance roller that is disposed upstream of the registration roller in a conveyance path of the print paper to abut the print paper against the registration roller; Equipped with The conveying control unit is an image forming device that controls the reverse movement of the registration roller and the pushing operation of the printing paper by the conveying roller based on the tilt detected by the detection unit and information about the printing paper after the printing paper is pressed against the registration roller. <2> The transport control unit determining whether the thickness of the printing paper is equal to or greater than a predetermined threshold; When the paper thickness is less than the predetermined threshold value, the pushing operation by the conveying roller is not performed, and the registration roller is rotated in the reverse direction. <1> 2. The image forming apparatus according to claim 1, wherein: <3> The transport control unit determining whether the tilt detected by the detection unit is equal to or greater than a predetermined threshold; When the inclination is less than the predetermined threshold value, the pushing operation by the conveying roller is not performed, and the registration roller is rotated in the reverse direction. <1> or <2> 2. The image forming apparatus according to claim 1, wherein: <4> The transport control unit determining whether the tilt detected by the detection unit is equal to or greater than a first threshold value; determining whether the thickness of the printing paper is equal to or greater than a second threshold value; When the inclination is equal to or greater than the first threshold value and the paper thickness is equal to or greater than the second threshold value, the registration rollers are rotated in the reverse direction and the conveying rollers press the printing paper against the registration rollers. <1> ~ <3> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <5> a storage unit that stores association information that associates at least the inclination of the printing paper with the pushing amount of the pushing operation by the conveyance roller, The transport control unit determining a press-down amount associated with the tilt detected by the detection unit using the association information; the conveying roller presses the printing paper against the registration roller by the determined pressing amount; <1> 2. The image forming apparatus according to claim 1, wherein: <6> the association information associates the inclination of the printing paper, and at least one of the thickness, length, and type of the printing paper with the pushing amount of the pushing operation by the conveyance roller; The transport control unit determines the pushing amount using the association information. <5> 2. The image forming apparatus according to claim 1, wherein: <7> the conveyance control unit reverses the rotation of the registration rollers and causes the conveyance rollers to press the printing paper against the registration rollers by the determined pressing amount. <5> or <6> 2. The image forming apparatus according to claim 1, wherein: <8> The transport control unit stops operation when the thickness of the printing paper exceeds a predetermined upper limit. <1> ~ <7> 10. The image forming apparatus according to claim 9, wherein the first and second electrodes are arranged parallel to each other. <9> A printing paper transport method in an image forming apparatus, comprising: a detection step of detecting the inclination of the printing paper based on detection information from a sensor disposed on the conveyance path for detecting the printing paper; a transport control step of driving a transport roller disposed upstream of the registration roller in a transport path of the print paper to a print sheet conveyance path while the registration roller that conveys the print sheet to an image forming unit is stopped from rotating, thereby causing the print sheet to abut against the registration roller; a step of controlling the reverse rotation of the registration rollers and the pushing operation of the conveying rollers to push the printing paper in based on the detected inclination and information about the printing paper after the printing paper has been brought into contact with the registration rollers; This is a transport method having the above structure. <10> On the computer, a detection step of detecting the inclination of the printing paper based on detection information from a sensor disposed on the conveyance path for detecting the printing paper; a transport control step of driving a transport roller disposed upstream of the registration roller in a transport path of the print paper to a print sheet conveyance path while the registration roller that conveys the print sheet to an image forming unit is stopped from rotating, thereby causing the print sheet to abut against the registration roller; a step of controlling the reverse rotation of the registration rollers and the pushing operation of the conveying rollers to push the printing paper in based on the detected inclination and information about the printing paper after the printing paper has been brought into contact with the registration rollers; This is a program for executing the above. [Explanation of symbols]

[0075] 10 Image forming device 11 Controller 12 Image forming unit 20 DFE 101 Paper position detection unit 102 Tilt detection unit 103 Transport control unit 104 Printing control unit 105 Storage section 501 CPU 502 ROM 503 RAM 504 Engine Interface 505 Sensor Interface 506 Storage device 507 DFE Interface 508 Drive Circuit 510 Bus 700 Paper Tray 701 Registration roller 702 Intermediate transfer belt 703, 703C, 703K, 703M, 703Y Photoconductor Drum 704 Transfer roller 705 Fuser roller 706 Reversing roller 707 Double-sided paper feed roller 708, 709 Conveyor rollers 710 Non-contact sensor P printing paper [Prior art documents] [Patent documents]

[0076] [Patent Document 1] Japanese Patent Application Publication No. 2017-109837

Claims

1. a detection unit that detects the inclination of the printing paper based on detection information from a sensor that detects the printing paper, the sensor being disposed on the conveyance path; a conveyance control unit that, while a registration roller that conveys the print paper to an image forming unit is stopped from rotating, drives a conveyance roller that is disposed upstream of the registration roller in a conveyance path of the print paper to abut the print paper against the registration roller; Equipped with The conveying control unit of the image forming apparatus controls the reverse movement of the registration roller and the pushing operation of the conveying roller to push the printing paper based on the tilt detected by the detection unit and information about the printing paper after the printing paper has been pressed against the registration roller.

2. The transport control unit determining whether the thickness of the printing paper is equal to or greater than a predetermined threshold; 2. The image forming apparatus according to claim 1, wherein when the paper thickness is less than the predetermined threshold, the conveying roller does not perform a pushing operation, and the registration roller performs a reverse rotation operation.

3. The transport control unit determining whether the tilt detected by the detection unit is equal to or greater than a predetermined threshold; 3. The image forming apparatus according to claim 1, wherein when the inclination is less than the predetermined threshold value, the pushing operation by the conveying roller is not performed, and the registration roller is rotated in the reverse direction.

4. The transport control unit determining whether the tilt detected by the detection unit is equal to or greater than a first threshold value; determining whether the thickness of the printing paper is equal to or greater than a second threshold value; 2. The image forming apparatus according to claim 1, wherein, when the inclination is equal to or greater than the first threshold value and the paper thickness is equal to or greater than the second threshold value, the registration rollers are rotated in reverse and the conveying rollers press the printing paper against the registration rollers.

5. a storage unit that stores association information that associates at least the inclination of the printing paper with the pushing amount of the pushing operation by the conveyance roller, The transport control unit determining a press-down amount associated with the tilt detected by the detection unit using the association information; 2. The image forming apparatus according to claim 1, wherein the transport roller presses the printing paper against the registration roller by the determined pressing amount.

6. the association information associates the inclination of the printing paper, and at least one of the thickness, length, and type of the printing paper with the pushing amount of the pushing operation by the conveyance roller; The image forming apparatus according to claim 5 , wherein the transport control unit determines the pressing amount using the association information.

7. 7. The image forming apparatus according to claim 5, wherein the transport control section reverses the rotation of the registration rollers and causes the transport rollers to press the printing paper against the registration rollers by the determined pressing amount.

8. 3. The image forming apparatus according to claim 1, wherein the transport control unit stops operation when the thickness of the printing paper exceeds a predetermined upper limit.

9. A printing paper transport method in an image forming apparatus, comprising: a detection step of detecting the inclination of the printing paper based on detection information from a sensor disposed on the conveyance path for detecting the printing paper; a transport control step of driving a transport roller disposed upstream of the registration roller in a transport path of the print paper to a print sheet conveyance path while the registration roller that conveys the print sheet to an image forming unit is stopped from rotating, thereby causing the print sheet to abut against the registration roller; a step of controlling the reverse rotation of the registration rollers and the pushing operation of the conveying rollers to push the printing paper in based on the detected inclination and information about the printing paper after the printing paper has been brought into contact with the registration rollers; A transport method comprising:

10. On the computer, a detection step of detecting the inclination of the printing paper based on detection information from a sensor disposed on the conveyance path for detecting the printing paper; a transport control step of driving a transport roller disposed upstream of the registration roller in a transport path of the print paper to a print sheet conveyance path while the registration roller that conveys the print sheet to an image forming unit is stopped from rotating, thereby causing the print sheet to abut against the registration roller; a step of controlling the reverse rotation of the registration rollers and the pushing operation of the conveying rollers to push the printing paper in based on the detected inclination and information about the printing paper after the printing paper has been brought into contact with the registration rollers; A program to execute.

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