Image forming apparatus and computer program product

Abstract

The invention relates to an image forming apparatus and a computer program product. An image forming apparatus that forms an image on a recording medium through a plurality of steps includes: a medium swinging mechanism that swings the recording medium in a medium width direction; a medium detection unit that detects a position of an end portion of the recording medium in the medium width direction; a tape correction mechanism that corrects the position of the tape in the medium width direction for executing one of the steps of image formation; a tape detection unit that detects the position of the end of the tape in the medium width direction; and a control device that performs a first correction control for correcting the position of the end of the recording medium by the medium swing mechanism on the basis of the detection by the medium detection unit, and a second correction control for correcting the position of the end of the tape by the tape correction mechanism on the basis of the detection by the tape detection unit. The control device corrects the second correction control when the first correction control is performed in a state in which the recording medium crosses both the medium swing mechanism and the belt.

Description

Technical Field

[0001] This disclosure relates to an image forming apparatus and a computer program product. Background Technology

[0002] In an image forming apparatus, the sheet-like recording medium used for image forming may shift in a direction intersecting the transport direction of the recording medium due to various reasons.

[0003] Thus, when the recording medium is offset, the image formation position relative to the recording medium deviates from its original reasonable position.

[0004] Conventionally, the offset was corrected by clamping the recording medium, which had become offset, with a registration roller and swinging it in the width direction of the medium (for example, see Patent Document 1).

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-64810

[0006] In an image forming apparatus that forms an image on a recording medium via multiple image forming steps, a tape in contact with the recording medium is used in a part of the process.

[0007] In this situation, sometimes offset correction based on the registration roller (hereinafter referred to as alignment correction) is performed while the recording medium is in contact with the tape. As a result, the tape is pulled by the paper and moves, which may affect the quality of image formation. Summary of the Invention

[0008] The subject of this disclosure is to suppress the effect of band shift caused by alignment correction.

[0009] To address the aforementioned problems, this disclosure provides an image forming apparatus that forms an image on a recording medium through multiple steps, comprising:

[0010] The media oscillation mechanism causes the recording medium to oscillate along the media width direction that intersects with the transport direction of the recording medium.

[0011] The medium detection unit detects the position of the end of the recording medium in the width direction of the medium.

[0012] The belt has a correction mechanism that corrects the position of the belt in the width direction of the recording medium that is in contact with the recording medium and performs any one of the above-mentioned processes.

[0013] The belt detection unit detects the position of the end of the belt in the width direction of the medium; and

[0014] The control device performs a first correction control and a second correction control. In the first correction control, the media oscillation mechanism corrects the position of the end of the recording medium based on the detection of the media detection unit. In the second correction control, the belt correction mechanism corrects the position of the end of the belt based on the detection of the belt detection unit.

[0015] When the control device performs the first correction control while the recording medium spans both sides of the medium swing mechanism and the belt, it corrects the second correction control.

[0016] Another disclosure is a computer program product in which the image forming apparatus includes: a medium oscillation mechanism for oscillating a recording medium along a medium width direction intersecting the transport direction of the recording medium; a medium detection unit for detecting the position of the end of the recording medium in the medium width direction; a belt correction mechanism for correcting the position of the belt in the medium width direction of the belt that contacts the recording medium and performs one of the steps of image formation on the recording medium; and a belt detection unit for detecting the position of the end of the belt in the medium width direction.

[0017] The aforementioned computer program enables the computer of the aforementioned image forming apparatus to perform the following functions:

[0018] The function of performing the first correction control is to correct the position of the end of the recording medium by the medium swing mechanism based on the detection of the medium detection unit.

[0019] The function of performing a second correction control, in which the belt correction mechanism corrects the position of the end of the belt based on the detection by the belt detection unit; and

[0020] When the first correction control is performed with the recording medium spanning both sides of the medium swing mechanism and the belt, the function of correcting the second correction control is provided.

[0021] According to this disclosure, the effect of band shift caused by alignment correction can be suppressed. Attached Figure Description

[0022] Figure 1 This is a schematic structural diagram illustrating the image forming apparatus of this embodiment.

[0023] Figure 2 This is a three-dimensional view of the intermediate transfer belt, which is tensioned and supported within the device, as observed from the downstream side of the media transport direction.

[0024] Figure 3 From Figure 1View the upper part of the transfer belt from the inside of the paper.

[0025] Figure 4 This is a three-dimensional view of the upper part of the intermediate transfer belt as observed from the downstream side of the media transport direction.

[0026] Figure 5 This is an explanatory diagram showing the oscillation process of paper based on the alignment roller.

[0027] Figure 6 This is a perspective view showing the structure of the heating side located on the upper side of the fixing device.

[0028] Figure 7 Observing from different directions and Figure 6 A 3D diagram of the same structure.

[0029] Figure 8 It is to further observe and from different directions Figure 6 A 3D diagram of the same structure.

[0030] Figure 9 It is a brief representation Figure 1 A block diagram of the structure of the control system of the image forming apparatus.

[0031] Figure 10 It is a flowchart of the operation control performed by the control unit on each part of the image forming apparatus during the transport of the recording medium.

[0032] Explanation of reference numerals in the attached drawings: 6… intermediate transfer belt; 61… steering roller; 62… first steering mechanism (with correction mechanism); 621… steering motor; 63… first offset detection device (with detection unit); 633… first sensor; 634… second sensor; 7Y, 7M, 7C, 7K… primary transfer roller; 9… secondary transfer roller; 10… image forming unit; 11… control unit (control device); 12… storage unit; 20… media transport unit; 27… registration roller; 271… registration motor; 33… media sensor (media detection unit); 34… media oscillation mechanism; 3 5…Image reading unit; 50…Fixing device; 51…First heating roller; 52…Second heating roller; 53…Fixing belt; 54…Pressure roller; 55…Second steering mechanism (with correction mechanism); 551…Steering motor; 56…Second offset detection device (with detection unit); 563~565…First~Third sensors; 100…Image forming apparatus; CD…Media width direction; FD…Media transport direction; P…Recording medium; SE1…Alignment sensor; SE2…Position detection sensor (media detection unit); SE3…Environmental sensor; Tp…Target position. Detailed Implementation

[0033] Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. However, the scope of the disclosure is not limited to the examples in the drawings.

[0034] [Summary of the various structures of the image forming apparatus]

[0035] First, the structure of the image forming apparatus 100 in this embodiment will be described.

[0036] Figure 1 This is a schematic structural diagram illustrating the image forming apparatus 100 of this embodiment. The image forming apparatus 100 is, for example, an electronic photographic image forming apparatus 100 such as a photocopier. The image forming apparatus 100 is a series-type apparatus that forms a color image by arranging a plurality of photoreceptors opposite to an intermediate transfer belt in a longitudinal direction. While the color, series-type is an example of this embodiment, other image forming apparatuses may also be illustrated.

[0037] The recording medium P used by the image forming apparatus 100 for image forming is not limited to ordinary paper or other types of recording paper. The recording medium P includes all sheet-like recording media capable of image forming, such as cut paper, continuous paper, strip paper, and OHP sheets.

[0038] The image forming apparatus 100 includes a document reading device SC, an image forming unit 10, a fixing device 50, an image reading unit 35, a media transport unit 20, and a control unit 11. The image forming apparatus 100 houses them in a single enclosure.

[0039] [Manuscript Reading Device]

[0040] The document reading device SC scans and exposes the image of the original document using the optical system of the scanning exposure device, and obtains an image signal by reading the reflected light through a line image sensor. This image signal, after undergoing A / D conversion, shadow correction, compression, and other processing, is input to the control unit 11 as image data. Furthermore, the image data input to the control unit 11 is not limited to what is read by the document reading device SC. Image data can also be, for example, data received from a personal computer or other image forming apparatus via the communication unit 13.

[0041] [Image Forming Unit]

[0042] The image forming unit 10 is configured to include four sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 6, and a secondary transfer roller 9. The image forming units 10Y, 10M, 10C, and 10K are image forming units for each color of Y, M, C, and K. In the accompanying reference numerals, "Y" indicates image formation related to yellow, "M" indicates image formation related to magenta, "C" indicates image formation related to cyan, and "K" indicates image formation related to black.

[0043] The image forming unit 10Y includes a photosensitive drum 1Y and a charged section 2Y, a light writing section 3Y, a developing device 4Y, and a drum cleaner 5Y disposed around it.

[0044] The image forming unit 10M includes a photosensitive drum 1M, a charged part 2M, a light writing part 3M, a developing device 4M, and a drum cleaner 5M disposed around it.

[0045] The image forming unit 10C includes a photosensitive drum 1C and a charged part 2C, a light writing part 3C, a developing device 4C, and a drum cleaner 5C disposed around it.

[0046] The image forming unit 10K includes a photosensitive drum 1K and a charged section 2K, a light writing section 3K, a developing device 4K, and a drum cleaner 5K disposed around it.

[0047] The photosensitive drums 1Y to 1K are uniformly charged on their surfaces by the charged sections 2Y to 2K. Furthermore, a latent image is formed on the photosensitive drums 1Y to 1K through scanning exposure based on the light writing sections 3Y to 3K. The developing apparatus 4Y to 4K then develops the latent image on the photosensitive drums 1Y to 1K using toner. Thus, toner images of specified colors corresponding to yellow, magenta, cyan, and black are formed on the photosensitive drums 1Y to 1K. The toner images formed on the photosensitive drums 1Y to 1K are sequentially transferred to the intermediate transfer belt 6 via primary transfer rollers 7Y, 7M, 7C, and 7K.

[0048] Intermediate transfer belt 6 is a belt used in the intermediate transfer process that carries the toner image and performs a secondary transfer to the recording medium P.

[0049] An image of toner composed of various colors transferred onto the intermediate transfer belt 6 is transferred onto the recording medium P via a secondary transfer roller 9. The secondary transfer roller 9 is a pressing component that forms a roller gap (hereinafter referred to as "transfer roller gap") by pressing it against the intermediate transfer belt 6.

[0050] [Image forming section: periphery of the intermediate transfer belt]

[0051] Figure 2 This is a perspective view of the intermediate transfer belt 6, which is tensioned and supported within the device, as observed from the downstream side of the media transport direction FD. Figure 3 From Figure 1 View the upper part of the transfer belt 6 from the inside of the paper. Figure 4 This is a three-dimensional view of the upper part of the intermediate transfer belt 6 as observed from the downstream side of the media transport direction FD.

[0052] Furthermore, the media transport direction FD is a sub-scanning direction, that is, a direction parallel to the transport direction when the recording medium P is transported in the media transport unit 20 with a reasonable orientation. Additionally, in the following description, the direction parallel to the recording medium P and intersecting the media transport direction FD is defined as the media width direction CD. More specifically, the media width direction CD exemplifies a direction orthogonal to the media transport direction FD. Furthermore, a reasonable orientation refers to an orientation in which one side of the media width direction CD of the recording medium P is parallel to a predetermined transport direction in the media transport unit 20.

[0053] The various structures of the image forming apparatus 100 are sometimes described using the medium transport direction FD and the medium width direction CD.

[0054] The intermediate transfer belt 6 is composed of an endless ring belt with polyimide as the base material and a coating on the surface that enables mold release.

[0055] Some or all of the multiple rollers that tension the intermediate transfer belt 6 can also be configured to be driven by a motor for rotation.

[0056] The upper side of the intermediate transfer belt 6 is tensioned in a mountain shape by three rollers, and the lower side is tensioned by two rollers. Furthermore, the number of rollers supporting the intermediate transfer belt 6 is just one example; it can be increased or decreased within a range of more than two.

[0057] One of the lower rollers forms a gap with the secondary transfer roller 9 mentioned above, and the toner image is transferred from the middle transfer belt 6 to the recording medium P.

[0058] The roller at the apex of the three rollers on the upper side is the guide roller 61. The rotation axes of the five rollers mentioned above, including the guide roller 61, are in principle parallel to the direction of the medium width CD.

[0059] Furthermore, the steering roller 61 can tilt its rotation axis via the first steering mechanism 62, which serves as a correction mechanism. By tilting its rotation axis, the steering roller 61 can correct the position of the intermediate transfer belt 6 in the media width direction CD.

[0060] like Figure 3 As shown, the first steering mechanism 62 can use the steering motor 621 as a drive source to rotate the outer peripheral cam 622 at any angle via a reduction mechanism. One end of the steering roller 61 in the medium width direction CD is rotatably supported by a lever member 623 extending in the vertical direction.

[0061] Furthermore, the outer peripheral cam 622 has a shape in which the outer diameter increases or decreases along the circumferential direction. The outer periphery of the outer peripheral cam 622 abuts against the lower end of the lever member 623 on the downstream side in the medium conveying direction FD. Therefore, if the outer peripheral cam 622 rotates, the upper end of the lever member 623 swings, and the rotation axis of the guide roller 61 tilts.

[0062] If the rotation axis of the guide roller 61 tilts, the intermediate transfer belt 6 moves in any direction along the media width direction CD, depending on the direction of its tilting motion. Therefore, if the intermediate transfer belt 6 deviates in any direction along the media width direction CD, the deviation can be corrected by moving it in the opposite direction.

[0063] The offset of the media width direction CD of the intermediate transfer belt 6 can be detected by the first offset detection device 63, which serves as the belt detection unit.

[0064] The first offset detection device 63 is located above the intermediate transfer belt 6 and detects the position of one end of the medium width direction CD on the medium width direction CD.

[0065] like Figure 4 As shown, the first offset detection device 63 has a detection arm 631, a swing arm 632, a first sensor 633, a second sensor 634, and a support plate 635.

[0066] The detection arm 631 is rotatably supported on the support plate 635. The rotating end of the detection arm 631 abuts against one end of the intermediate transfer belt 6 in the media width direction CD. In addition, the detection arm 631 is given a weak spring pressure by the spring 636 to maintain the abutment state relative to the intermediate transfer belt 6.

[0067] The swing arm 632 is connected to the detection arm 631 and rotates integrally. Furthermore, the detection arm 631 is provided with a plate-shaped detection section 631a that is detected by the first sensor 633. Additionally, the swing arm 632 is provided with a plate-shaped detection section 632a that is detected by the second sensor 634.

[0068] The first and second sensors 633 and 634 have detection elements for optically detecting each of the detected parts 631a and 632a. Each detection element may also be an element that detects the presence or absence of the detected parts 631a and 632a within its detection range. Alternatively, each detection element may be an element that detects the position and amount of movement of the detected parts 631a and 632a in a predetermined direction, like a line sensor.

[0069] In the former case, each detection element can determine whether the position of the intermediate transfer belt 6 in the media width direction CD is suitable by combining the presence or absence of the detected parts 631a and 632a. For example, one combination mode indicates that the intermediate transfer belt 6 is in a reasonable position in the media width direction CD. Another mode indicates that the intermediate transfer belt 6 is offset to one side of the media width direction CD. Yet another mode indicates that the intermediate transfer belt 6 is offset to the other side of the media width direction CD.

[0070] Furthermore, in the latter case, the offset of the intermediate transfer belt 6 relative to its proper position in the media width direction CD can be detected based on the detection quantity of the detected parts 631a and 632a. Therefore, it is possible to detect whether the position of the intermediate transfer belt 6 in the media width direction CD is proper, and to what extent it has shifted to one side or the other.

[0071] The control unit 11, as a control device, performs a second correction control relative to the first steering mechanism 62 based on the detection of the first offset detection device 63.

[0072] The second correction control performed by the control unit 11 relative to the first steering mechanism 62 will be described later.

[0073] [Media Transport Section]

[0074] The media transport unit 20 transports the recording medium P according to the transport path of the recording medium P. The recording medium P is housed in the supply tray 21, and is taken in by the supply roller 22a of the supply unit 22 and delivered to the transport path. Alternatively, the recording medium P is supplied from outside the image forming apparatus 100 through an external supply port and delivered to the transport path. For example, a recording medium P made of strips of paper is supplied to the image forming apparatus 100 via an external supply port.

[0075] In the aforementioned transport path, multiple transport mechanisms for transporting the recording medium P are provided upstream of the secondary transfer roller 9, near the gap between the transfer rollers. Each transport mechanism consists of a pair of rollers that are pressed together. Each transport mechanism transports the recording medium P by rotating at least one roller using a drive mechanism primarily composed of an electric motor. Furthermore, the pair of rollers constituting each transport mechanism is configured to switch between a pressed state and a separated state.

[0076] From the upstream to the downstream side of the transport path of the recording medium P, intermediate transport rollers 23-25, annular rollers 26, and alignment rollers 27 are provided. These transport mechanisms can be, in addition to a pair of rollers, belts to belts or a combination of belts and rollers.

[0077] [Media conveying section: alignment roller]

[0078] The recording medium P supplied to the transport path is sequentially conveyed by a plurality of intermediate transport rollers 23-25 ​​arranged from upstream to downstream and an annular roller 26. Furthermore, the leading edge of the recording medium P contacts the alignment roller 27, which is in a stopped state. The annular roller 26 continues to rotate for a predetermined time. This forms an annular ring on the recording medium P. Through the formation of this annular ring, the curvature of the leading edge of the recording medium P is corrected. In other words, the tilt of the recording medium P is corrected. Specifically, the leading edge of the recording medium P is parallel to the gap of the alignment roller 27, which is parallel to the width direction CD of the medium, thus correcting the curvature.

[0079] Next, the registration roller 27 begins to rotate at a predetermined time to synchronize with the toner image carried by the intermediate transfer belt 6. At this time, the intermediate transport rollers 23-25 ​​and the annular roller 26 are switched from a pressing state to a separated state. That is, when the intermediate transport rollers 23-25 ​​and the annular roller 26 are in a separated state, the recording medium P is transported only by the registration roller 27. The registration roller 27 transports the recording medium P to the intermediate transfer belt 6, which serves as the image carrier, and to the transfer roller gap of the secondary transfer roller 9, which serves as the transfer section. At this time, the registration roller 27 acts as an oscillating roller, transporting the recording medium P while performing the oscillation process described later.

[0080] Figure 5 This is an explanatory diagram illustrating the oscillation process of the recording medium P based on the alignment roller 27. The alignment roller 27 is configured to oscillate in the media width direction CD. A media oscillation mechanism 34, driven by a motor, is connected separately to the alignment roller 27 from the alignment motor 271 that drives the rotation. The alignment roller 27 can be driven by the media oscillation mechanism 34 to move in the media width direction CD from a predetermined initial position.

[0081] The alignment roller 27 moves along the width direction CD of the recording medium P as it passes through. This allows the transported recording medium P to move along the width direction CD (oscillation processing). Hereinafter, the movement of the recording medium P along the width direction CD based on the alignment roller 27 will be referred to as "oscillation of the recording medium P".

[0082] Therefore, the alignment roller 27 adjusts the transport position of the recording medium P in the media width direction CD to match the position of the toner image being transferred. Here, the position that the side end of the recording medium P should pass through in the media width direction CD is called the target position Tp. If the side end of the recording medium P passes through this target position Tp, the positional relationship between the recording medium P and the toner image is considered optimal. For example, it is the position where the center of the recording medium P in the width direction coincides with the center of the toner image in the width direction.

[0083] The alignment roller 27 is designated as the object of the first correction control, as described later. Therefore, the alignment roller 27 adjusts the transport position of the recording medium P in the media width direction CD so that the side end of the recording medium P becomes the target position Tp. The position of the toner image that represents the optimal positional relationship between the recording medium P and the toner image is called the optimal image position.

[0084] An alignment sensor SE1 and a position detection sensor SE2 are installed along the conveying path. The control unit 11 controls the operation of the alignment roller 27 based on the detection of sensor SE1.

[0085] In the conveying path, a positioning sensor SE1 is disposed between the positioning roller 27 and the annular roller 26. The positioning sensor SE1 detects the arrival of the leading edge of the recording medium P at a predetermined distance ahead of the positioning roller 27. The detection result of the positioning sensor SE1 is used to determine the timing of the start of rotation of the positioning roller 27.

[0086] In the transport path, a position detection sensor SE2, serving as a media detection unit, is provided downstream of the alignment roller 27 in the media transport direction FD. The position detection sensor SE2 is a detection unit that detects the position of the recording medium P in the media width direction CD at its side end. The position detection sensor SE2 is, for example, a linear image sensor in which multiple light-receiving elements are arranged in a straight line along the media width direction CD. The detection result of the position detection sensor SE2 is output to the control unit 11 for determining oscillation control information for the alignment roller 27 during oscillation processing. Furthermore, the operation of the media oscillation mechanism 34 is controlled based on this determination.

[0087] The control unit 11 performs a first correction control based on the detection of the position detection sensor SE2, causing the medium swing mechanism 34 to perform a correction of the position of the end of the recording medium P.

[0088] The first correction control performed by the control unit 11 on the medium swing mechanism 34 will be described later.

[0089] [Media Delivery Section: Media Sensor]

[0090] Along the conveying path, a medium sensor 33, serving as a medium detection unit, is provided between the intermediate conveying roller 24 and the intermediate conveying roller 25.

[0091] The medium sensor 33 detects the physical properties of the recording medium P. The medium sensor 33 includes a thickness sensor, a moisture content sensor, a basis weight sensor, and a stiffness sensor. The thickness sensor detects the thickness of the recording medium P. The moisture content sensor detects the moisture content of the recording medium P. The basis weight sensor detects the basis weight of the recording medium P. The stiffness sensor detects the stiffness of the recording medium P.

[0092] [Fixing device]

[0093] Figure 6 This is a perspective view showing the structure disposed on the upper heating side of the fixing device 50. Figure 7 Observing from different directions and Figure 6 A 3D diagram of the same structure. Figure 8 It is to further observe and from different directions Figure 6 A 3D diagram of the same structure.

[0094] The fixing device 50 is a device that performs fixing processing on the recording medium P on which the toner image has been transferred, that is, on the recording medium P fed out from the gap of the transfer roller.

[0095] The fixing device 50 includes, for example, first and second heating rollers 51 and 52, fixing belt 53, pressure roller 54, second steering mechanism 55, and second offset detection device 56.

[0096] The first and second heating rollers 51 and 52 are located on the upper side of the conveying path of the recording medium P, and are configured in principle with their rotation axis parallel to the width direction CD of the medium.

[0097] The heater with a built-in heating source in the first heating roller 51 is located on the upper side of the second heating roller 52.

[0098] A fixing belt 53 is installed between the first heating roller 51 and the second heating roller 52 in a tensioned state.

[0099] The second heating roller 52 forms a gap with the pressure roller 54 via the fixing belt 53, and performs fixing of the recording medium P passing through the gap.

[0100] The pressure roller 54 is configured to press against the second heating roller 52 via the fixing belt 53 with its rotation axis parallel to the width direction CD of the medium. Any one of the rollers 51, 52, and 54 can be used, but the example shown is a structure in which the pressure roller 54 is driven by a motor to rotate.

[0101] The fixing belt 53 is a belt used to perform the process of fixing the toner image onto the recording medium P. The fixing belt 53 is composed of an endless loop belt with a polyimide substrate and a coating on the surface that provides release properties.

[0102] During the transport of the recording medium P, the fixing device 50 fixes the toner image onto the recording medium P through pressurization and heating.

[0103] Furthermore, the second steering mechanism 55 can tilt the rotation axis relative to the first heating roller 51. The tilting motion of the first heating roller 51 via its rotation axis enables positional correction of the media width direction CD of the fixing belt 53.

[0104] like Figure 7As shown, the second steering mechanism 55 can use the steering motor 551 as a drive source to rotate the outer peripheral cam 552 at any angle via a reduction mechanism. If the outer peripheral cam 552 rotates, one end of the first heating roller 51 in the medium width direction CD will move in a predetermined direction.

[0105] If the rotation axis of the first heating roller 51 tilts, the fixing belt 53 will move in any direction along the media width direction CD, depending on the direction of its tilting motion. Therefore, if the fixing belt 53 deviates in any direction along the media width direction CD, the deviation can be corrected by moving it in the opposite direction.

[0106] The offset of the fixing tape 53 in the medium width direction CD can be detected by the second offset detection device 56, which serves as a tape detection unit.

[0107] like Figure 8 As shown, the second offset detection device 56 is located above the fixing belt 53 and detects the position of one end of the medium width direction CD on the medium width direction CD.

[0108] The second offset detection device 56 includes a detection arm 561, a first sensor 563, a second sensor 564, a third sensor 565, and a support plate 566.

[0109] The detection arm 561 is rotatably supported on the support plate 566. The detection arm 561 has a cylindrical detection piece 562 that abuts against one end of the intermediate transfer belt 6 in the media width direction CD. In addition, the detection arm 561 is given a weak spring pressure by a spring (not shown) to maintain the abutment state relative to the fixing belt 53.

[0110] The detection arm 561 is provided with plate-shaped detection parts 561a to 561c that are detected by the first to third sensors 563 to 565.

[0111] The first to third sensors 563 to 565 have detection elements for optically detecting each of the detected parts 561a to 561c. Each detection element may also be an element that detects the presence or absence of the detected parts 561a to 561c within its detection range. Alternatively, each detection element may be an element that detects the position and amount of movement of the detected parts 561a to 561c in a predetermined direction, like a line sensor.

[0112] In the former case, each detection element detects a combination of the presence or absence of the detected parts 561a to 561c. Furthermore, by detecting each pattern, it is possible to determine whether the position of the fixing belt 53 in the media width direction CD is suitable. For example, one combination pattern indicates that the fixing belt 53 is within a reasonable range in the media width direction CD. Another pattern indicates that the fixing belt 53 is offset to one side of the media width direction CD. Yet another pattern indicates that the fixing belt 53 is offset to the other side of the media width direction CD.

[0113] Furthermore, in the latter case, the position of the fixing belt 53 in the media width direction CD can be detected based on the detection amount of the detected parts 561a to 561c. Therefore, it is possible to detect whether the position of the fixing belt 53 in the media width direction CD is within a reasonable range, and what degree of offset it has caused in one direction or the other.

[0114] The control unit 11 performs a second correction control relative to the second steering mechanism 55 based on the detection of the second offset detection device 56.

[0115] The second correction control performed by the control unit 11 relative to the second steering mechanism 55 will be described later.

[0116] [Image Reading Unit]

[0117] The image reading unit (ICCU) 35 is configured to include, for example, a linear image sensor (e.g., a CCD line sensor), an optical system, and a light source. The image reading unit 35 reads the recording medium P on which a toner image has been transferred and outputs the obtained read image to the control unit 11. Furthermore, in this embodiment, the image reading unit 35 is capable of measuring the color of the toner image on the recording medium P. The image reading unit 35 is not particularly limited as long as it can at least identify an area of ​​the recording medium P and an area of ​​the toner image. In this embodiment, the image reading unit 35 is located downstream of the fixing device 50 and near the front of the transport path via the switching gate 30. The image reading unit 35 only needs to be downstream of the secondary transfer roller 9 and capable of reading the positions of both sides of the recording medium P. Alternatively, it may be able to read the positions of the recording medium P side by side.

[0118] Alternatively, the image reading unit 35 can be configured as an optional device downstream of the image forming apparatus 100.

[0119] The recording medium P, which has undergone fixing processing by the fixing device 50, is read by the image reading unit 35. Furthermore, the recording medium P is discharged via the discharge roller 28 to the discharge tray 29 mounted on the outer side of the frame. Additionally, if image formation is also performed on the back side of the recording medium P, the recording medium P, after image formation on the paper surface has been completed, is read by the image reading unit 35. The recording medium P is then conveyed via the switching gate 30 to the reversing roller 31 located below. After the reversing roller 31 clamps the rear end of the conveyed recording medium P, it reverses the recording medium P by reverse feeding and is sent out onto the resupply transport path. The recording medium P sent to this resupply transport path is conveyed to the registration roller 27 via multiple resupply transport mechanisms. Furthermore, the recording medium P returns to the transfer roller gap via the registration roller 27. In addition, the discharge roller 28, the switching gate 30, the reversing roller 31, and the resupply transport mechanisms also constitute the aforementioned media transport unit 20.

[0120] [Control system of the image forming apparatus]

[0121] Figure 9 This is a block diagram that briefly illustrates the structure of the control system of the image forming apparatus 100 in this embodiment.

[0122] The control unit 11 is connected to the storage unit 12, the communication unit 13, the operation unit 14, the original document reading device SC, the image forming unit 10, the media transport unit 20, and the fixing device 50. Furthermore, the control unit 11 is connected to the image reading unit 35, the alignment sensor SE1, the position detection sensor SE2, the environmental sensor SE3, and the media sensor 33. The control unit 11 is composed of a CPU, RAM, etc.

[0123] The CPU of the control unit 11 reads the system program and various processing programs stored in the storage unit 12 and expands them in RAM. Furthermore, the control unit 11 centrally controls the operation of each part of the image forming apparatus 100 according to the expanded program.

[0124] For example, if an image formation task execution command is input through the operation unit 14, the control unit 11 executes the image formation task. Specifically, the control unit 11 controls the formation of a toner image on the recording medium P based on image data input by the document reading device SC and the communication unit 13.

[0125] Furthermore, the first correction control, the second correction control, and the correction processing for the second correction control, described later, are all based on the processing program stored in the storage unit 12. These controls and processes are implemented by the CPU of the control unit 11 executing each processing program.

[0126] The storage unit 12 is composed of non-volatile semiconductor memory, HDD (Hard Disk Drive), etc. In addition to the various programs executed by the control unit 11, the storage unit 12 also stores parameters, data, etc. required by each unit.

[0127] The communication unit 13 is equipped with various interfaces for connecting to external devices. These interfaces include NIC (Network Interface Card), MODEM (Modulator-Demodulator), and USB (Universal Serial Bus).

[0128] The operation unit 14 outputs various information set by the user to the control unit 11. For example, the operation unit 14 can be a touch panel that allows input operations based on information displayed on the screen.

[0129] Through the aforementioned operation unit 14, the user can set image formation settings. These settings include image density, magnification, presence or absence of double-sided printing, and transport conditions of the recording medium P. Furthermore, the transport conditions of the recording medium P include the transport speed of the recording medium P, the type of the recording medium P (e.g., size, paper type), and the supply tray used. The size of the recording medium P includes both the dimension in the media transport direction FD and the dimension in the media width direction CD. This image formation setting information is stored in the storage unit 12.

[0130] Furthermore, the thickness, moisture content, basis weight, and stiffness of the recording medium P detected by the aforementioned media sensor 33 are also stored in the storage unit 12 as transport conditions for the recording medium P. The media sensor 33 performs detection repeatedly and periodically. Therefore, the setting information of the thickness, moisture content, basis weight, and stiffness of the recording medium P in the storage unit 12 is updated sequentially.

[0131] In addition, users can input task execution commands and adjust action instructions in the mode through the operation unit 14. Furthermore, the control unit 11 can display various messages to the user via the operation unit 14 by controlling the operation unit 14.

[0132] The environmental sensor SE3 is configured to include a temperature sensor, a humidity sensor, etc., to detect the temperature and humidity within the frame of the image forming apparatus 100, and output the detection results to the control unit 11.

[0133] [Control executed by the control unit: First corrective control for the medium oscillation mechanism]

[0134] The control unit 11 performs a first correction control (medium correction control) on the medium swing mechanism 34 to correct the offset of the medium width direction CD during the transport of the recording medium P.

[0135] If the control unit 11 detects a deviation of the recording medium P in the media width direction CD relative to the target position Tp, it controls the media swing mechanism 34 to eliminate the deviation. The deviation of the recording medium P in the media width direction CD relative to the target position Tp is detected by the position detection sensor SE2.

[0136] For ease of explanation, sometimes one side of the medium width direction CD is referred to as "left" and the other side as "right".

[0137] During the driving of the alignment roller 27, the control unit 11 periodically monitors the output of the position detection sensor SE2. As a result, the control unit 11 acquires offset information indicating the magnitude of the offset of the recording medium P relative to the target position Tp. Furthermore, the offset information includes a numerical value indicating the magnitude of the offset and a direction indicating whether the offset is left or right.

[0138] If the control unit 11 acquires offset information, it determines the oscillation speed of the media oscillation mechanism 34 based on the magnitude of the offset. The oscillation speed of the media oscillation mechanism 34 refers to the movement speed of the alignment roller 27 along the media width direction CD based on the media oscillation mechanism 34.

[0139] At this time, the control unit 11 determines the direction of the swing speed of the media swing mechanism 34 to be in the opposite direction based on the direction of the offset contained in the offset information. For example, if the offset of the recording medium P is to the left, the alignment roller 27 is made to swing to the right, and if the offset of the recording medium P is to the right, the alignment roller 27 is made to swing to the left.

[0140] The control unit 11 determines the swing speed of the medium swing mechanism 34 based on table data relating the swing speed of the medium swing mechanism 34 to the magnitude of the offset. Alternatively, the control unit 11 may calculate the swing speed of the medium swing mechanism 34 based on the magnitude of the offset through a predetermined calculation.

[0141] Furthermore, the oscillation speed of the media oscillation mechanism 34 should be increased or decreased in accordance with the transport speed of the recording medium P. Therefore, the control unit 11 reads the set value of the transport speed of the recording medium P from the transport conditions of the recording medium P in the storage unit 12. Moreover, the final oscillation speed is determined by multiplying a coefficient related to the transport speed of the recording medium P by the oscillation speed of the media oscillation mechanism 34, which is calculated based on the magnitude of the offset. Alternatively, a value related to the transport speed of the recording medium P may be added to or subtracted from the oscillation speed of the media oscillation mechanism 34, which is calculated based on the magnitude of the offset.

[0142] The control unit 11 drives the motor with the swing speed and direction of the media swing mechanism 34 as determined in the final decision, so that the alignment roller 27 swings in the media width direction CD.

[0143] As described above, the control unit 11 periodically reads the position detection sensor SE2, and thus executes the first correction control for the medium swing mechanism 34 each time.

[0144] [Controls executed by the control unit: Secondary correction control for the steering mechanism of the intermediate transfer belt]

[0145] The control unit 11 performs a second correction control (with correction control) on the first steering mechanism 62 that corrects the offset of the medium width direction CD during the transport of the intermediate transfer belt 6.

[0146] If the control unit 11 detects a deviation of the intermediate transfer belt 6 in the media width direction CD relative to the reasonable position, it controls the first steering mechanism 62 to eliminate the deviation. The deviation of the intermediate transfer belt 6 in the media width direction CD relative to the reasonable position is detected by the first deviation detection device 63.

[0147] During the transport of the intermediate transfer belt 6, the control unit 11 periodically monitors the output of the first offset detection device 63. Furthermore, the control unit 11 acquires offset information including the magnitude and direction of the offset of the intermediate transfer belt 6 relative to its proper position.

[0148] The control unit 11 determines the corrective movement speed and direction of the intermediate transfer belt 6 based on the magnitude and direction of the offset of the intermediate transfer belt 6 contained in the offset information. The control unit 11 may also utilize related table data that determines the magnitude of the offset of the intermediate transfer belt 6 and the corrective movement speed of the intermediate transfer belt 6.

[0149] Furthermore, the corrective movement speed of the intermediate transfer belt 6 in the media width direction CD should be increased or decreased in accordance with the transport speed of the recording medium P. Therefore, the control unit 11 reads the set value of the transport speed of the recording medium P from the transport conditions of the recording medium P in the storage unit 12. Moreover, the final corrective movement speed is determined by multiplying the corrective movement speed of the intermediate transfer belt 6 by the coefficient related to the transport speed of the recording medium P. Alternatively, a value related to the transport speed of the recording medium P may be added or subtracted from the corrective movement speed of the intermediate transfer belt 6 calculated based on the magnitude of the offset.

[0150] The corrective movement speed and direction of the intermediate transfer belt 6 are related to the tilt angle of the rotation axis of the guide roller 61. Furthermore, the tilt angle of the rotation axis of the guide roller 61 is related to the axis angle of the guide motor 621. Therefore, the control unit 11 can also utilize the table data that determines the relationship between the corrective movement speed of the intermediate transfer belt 6 and the axis angle of the guide motor 621.

[0151] Therefore, if the control unit 11 obtains the magnitude and direction of the offset of the intermediate transfer belt 6, it drives the steering motor 621 to make it the corresponding axis angle.

[0152] The control unit 11 periodically reads the first offset detection device 63, and therefore executes the second correction control for the first steering mechanism 62 each time.

[0153] [Controls executed by the control unit: Second correction control for the fixing belt steering mechanism]

[0154] The control unit 11 performs the second correction control (with correction control) of the second steering mechanism 55 to correct the offset of the medium width direction CD during the transport of the fixing tape 53.

[0155] If the control unit 11 detects a deviation of the fixing belt 53 in the media width direction CD relative to the reasonable position, it controls the second steering mechanism 55 to eliminate the deviation. The deviation of the fixing belt 53 in the media width direction CD relative to the reasonable position is detected by the second deviation detection device 56.

[0156] During the transport of the fixing belt 53, the control unit 11 periodically monitors the output of the second offset detection device 56. Furthermore, the control unit 11 acquires offset information including the magnitude and direction of the offset of the fixing belt 53 relative to its proper position.

[0157] The control unit 11 determines the correction movement speed and direction of the fixing belt 53 based on the magnitude and direction of the offset of the fixing belt 53 contained in the offset information. The control unit 11 may also use related table data that determines the magnitude of the offset of the fixing belt 53 and the correction movement speed of the fixing belt 53.

[0158] Furthermore, the correction movement speed of the fixing tape 53 in the media width direction CD should be increased or decreased in accordance with the transport speed of the recording medium P. Therefore, the control unit 11 reads the set value of the transport speed of the recording medium P from the transport conditions of the recording medium P in the storage unit 12. Moreover, the final correction movement speed is determined by multiplying the correction movement speed of the fixing tape 53 by a coefficient related to the transport speed of the recording medium P. Alternatively, a value related to the transport speed of the recording medium P is added or subtracted from the correction movement speed of the fixing tape 53 calculated based on the magnitude of the offset.

[0159] The corrective movement speed and direction of the fixing belt 53 are related to the tilt angle of the rotation axis of the first heating roller 51. Furthermore, the tilt angle of the rotation axis of the first heating roller 51 is related to the axis angle of the steering motor 551. Therefore, the control unit 11 can also utilize the table data that determines the relationship between the corrective movement speed of the fixing belt 53 and the axis angle of the steering motor 551.

[0160] Therefore, if the control unit 11 obtains the magnitude and direction of the offset of the fixing belt 53, it drives the steering motor 551 to achieve the corresponding axis angle.

[0161] The control unit 11 periodically reads the second offset detection device 56, and therefore executes the second correction control for the second steering mechanism 55 each time.

[0162] [Control executed by the control unit: Correction processing for the second correction control]

[0163] During the process of passing through the alignment roller 27, the recording medium P reaches the intermediate transfer belt 6 or the fixing belt 53, sometimes becoming a state that spans between them. If the recording medium P is subjected to the first correction control in this state, the intermediate transfer belt 6 or the fixing belt 53 may be pulled in the same direction by the oscillation of the recording medium P.

[0164] Therefore, in the case of the aforementioned slack, it is necessary to modify the correction movement speed of the second correction control based on the intermediate transfer belt 6 or the fixing belt 53.

[0165] First, the control unit 11 determines whether the alignment roller 27 and the intermediate transfer belt 6 or fixing belt 53 are crossed. The conveying distance from the alignment roller 27 to the roller gap of the intermediate transfer belt 6 or fixing belt 53 is design information and is a known value. Hereinafter, the conveying distance from the alignment roller 27 to the roller gap of the intermediate transfer belt 6 or fixing belt 53 will be referred to as the "belt distance".

[0166] The dimension of the recording medium P in the medium transport direction (hereinafter referred to as "medium transport length") can be obtained from the transport conditions of the recording medium P within the storage unit 12.

[0167] The control unit 11 determines that a crossover state has occurred when the length of the medium transport is greater than the distance between belts.

[0168] In addition, the control unit 11 can determine whether a crossover state has occurred by the elapsed time since the start of driving the alignment roller 27.

[0169] When the spanning state is generated, the control unit 11 performs correction processing on the correction movement speed based on the second correction control of the intermediate transfer belt 6 or the fixing belt 53.

[0170] Next, the correction process for the correction movement speed based on the second correction control will be explained. Here, the case where the intermediate transfer belt 6 is taken as the object is illustrated. The control unit 11 periodically and repeatedly performs the correction process when a cross-state is generated.

[0171] When the traverse state is generated, the control unit 11 calculates the correction speed and corrects the correction movement speed calculated by the second correction control.

[0172] First, the control unit 11 calculates a reference value for the correction speed. This reference value for the correction speed is determined based on the oscillation speed of the medium oscillation mechanism 34, which is determined by the first correction control. Furthermore, the direction of the correction speed is, in principle, opposite to the direction of the oscillation speed of the medium oscillation mechanism 34.

[0173] Hereinafter, the swing speed of the medium swing mechanism 34 determined by the first correction control will be set as "swing speed A". In addition, the reference value of the correction speed relative to the correction movement speed based on the second correction control will be set as "correction speed B".

[0174] For example, the control unit 11 calculates the corrected speed B by multiplying the swing speed A by a predetermined coefficient k1 (0 < k1 < 1).

[0175] B = k1·A

[0176] Furthermore, as an example, the swing speed A can also be calculated by adding or subtracting a specified value instead of multiplying by the coefficient k1, or by performing both operations to obtain the corrected speed B.

[0177] For example, when the recording medium P swings to the left via the alignment roller 27, a correction is made for the rightward movement component of the belt 6. At this time, if the rightward correction speed of the belt 6 is set via the second correction control, a correction that increases the rightward movement component is performed. Conversely, if the leftward correction speed of the belt 6 is set via the second correction control, a correction that decreases based on the rightward movement component is performed.

[0178] In addition, when the recording medium P swings to the right via the alignment roller 27, the opposite occurs.

[0179] Furthermore, sometimes the value of the correction speed B is greater than the correction movement speed of belt 6 determined by the second correction control. In this case, belt 6 moves in the opposite direction to the correction movement speed determined by the second correction control.

[0180] Next, the control unit 11 further corrects the correction speed B, which becomes the reference value, based on the prescribed parameters. The prescribed parameters in this case are the "dimensions in the transport direction FD", "dimensions in the media width direction CD", and "stiffness" of the recording medium P, which are included in the transport conditions of the recording medium P.

[0181] As described above, the "dimensionality in the transport direction FD" of the recording medium P is simply referred to as the "medium transport length". Additionally, the "dimensionality in the width direction CD" of the recording medium P is simply referred to as the "medium width".

[0182] If the media transport length increases, the effect of the movement of the belt 6 pulled by the recording medium P oscillating by the alignment roller 27 is reduced.

[0183] Therefore, the control unit 11 corrects the reduction in speed B due to the media conveying length. Specifically, the correction is performed using the value obtained by multiplying the media conveying length by a predetermined coefficient k2 (0 < k2). In the following formula, "L" represents the media conveying length, and "B1" represents the corrected speed.

[0184] B1=B-k2·L=k1·A-k2·L

[0185] If the width of the medium increases, the effect of the movement of the belt 6 pulled by the recording medium P, which is oscillating by the alignment roller 27, increases.

[0186] Therefore, the control unit 11 performs a correction that increases the correction speed B based on the medium width. Specifically, the correction is performed using the value obtained by multiplying the medium width by a predetermined coefficient k3 (0 < k3). In the following formula, "W" represents the medium width, and "B2" represents the correction speed.

[0187] B2=B1+k3·W=k1·A-k2·L+k3·W

[0188] If the stiffness increases, the effect of the movement of the belt 6, which is pulled by the recording medium P oscillating by the alignment roller 27, increases.

[0189] Therefore, the control unit 11 performs a correction of the speed B, which is increased according to the width of the medium. Specifically, the correction is performed using the value obtained by multiplying the stiffness by a predetermined coefficient k4 (0 < k4). In the following formula, "G" represents the stiffness, and "B3" represents the corrected speed.

[0190] B3=B2+k4·G=k1·A-k2·L+k3·W+k4·G

[0191] Furthermore, an example is shown of correcting the parameters of the correction speed B by multiplying the parameter values ​​by a specified coefficient and performing addition and subtraction operations, but this is not a limitation.

[0192] For example, a coefficient can be determined for each value of each parameter, and the correction speed B can be multiplied by the coefficient corresponding to the value of each parameter to make the correction.

[0193] Alternatively, it is preferable to correct each parameter of the correction speed B, but this is not always necessary. Or, the correction of each parameter of the correction speed B can be performed on any one or two of the media transport length, media width, and stiffness of the recording medium P.

[0194] Furthermore, the preferred correction speed B takes into account the transport speed of the recording medium P. At this point, the correction speed B is obtained by multiplying the oscillation speed A by a coefficient k1, where the oscillation speed A is a value that takes into account the transport speed of the recording medium P. Therefore, the correction speed B becomes a value that takes into account the transport speed of the recording medium P.

[0195] In addition, the preferred correction speed B takes into account the swing direction of the recording medium P and the offset direction of the band 6.

[0196] To reduce the influence of the oscillation direction of the recording medium P, the correction speed B is, in principle, corrected in the opposite direction to the oscillation direction. Furthermore, the correction values ​​for the correction speed B are adjusted in each direction based on the parameters. Therefore, the correction values ​​B1, B2, and B3 of the correction speed B are values ​​that take into account the oscillation direction of the recording medium P.

[0197] Furthermore, considering the offset direction of belt 6, the direction of the correction belt 6 and the direction of the correction speed B acting on belt 6 are considered to be consistent. As mentioned above, the direction of the correction speed B acting on belt 6 is opposite to the direction of the oscillation of the alignment roller 27.

[0198] When the direction of the correction belt 6 and the direction in which the correction speed B acts on the belt 6 are the same, the correction speed B can be increased. Alternatively, when the direction of the correction belt 6 and the direction in which the correction speed B acts on the belt 6 are opposite, the correction speed B can be decreased.

[0199] In addition, the control unit 11 performs the same correction processing on the fixing belt 53 as on the intermediate transfer belt 6, based on the correction movement speed of the second correction control.

[0200] In this configuration, the fixing belt 53 is located further away from the registration roller 27 than the intermediate transfer belt 6, which is sandwiched between them. Therefore, the influence of the fixing belt 53 on the registration wobbling is smaller than that of the intermediate transfer belt 6. Therefore, considering this situation, the coefficients k1 to k4 used to determine the correction speed B and the correction values ​​B1, B2, and B3 are adopted as values ​​smaller than those of the intermediate transfer belt 6.

[0201] [Motion control during recording media transport]

[0202] based on Figure 10 The flowchart explains the action control performed by the CPU of the control unit 11 on each part of the image forming apparatus 100 during the transport of the recording medium P.

[0203] When the recording medium P is started to be transported by the medium transport unit 20 and passes through the medium sensor 33, the control unit 11 detects the physical property value (S1) of the recording medium P. The thickness, moisture content, basis weight and stiffness of the recording medium P detected by the medium sensor 33 are stored in the storage unit 12 as the transport conditions of the recording medium P.

[0204] If the control unit 11 detects the front end of the recording medium P through the position detection sensor SE2 (S3), it reads the image formation setting information from the storage unit 12 (S5). Thus, the control unit 11 obtains the transport conditions of the recording medium P, such as the transport speed of the recording medium P, the direction FD and direction CD of the recording medium P, and the dimensions, weight, and stiffness of the recording medium P.

[0205] In addition, the control unit 11 starts the transport of the recording medium P based on the alignment roller 27 by driving the alignment motor 271 (S7).

[0206] Furthermore, the control unit 11 causes the front end of the recording medium P to come into contact with the gap of the alignment roller 27 to form an annular shape, thereby separating the intermediate transport rollers 23-25. The control unit 11 then begins detecting the offset of the recording medium P in the media width direction CD using the position detection sensor SE2. If an offset of the recording medium P is detected, the control unit 11 determines the oscillation speed and direction of the recording medium P based on the media oscillation mechanism 34. Consequently, the media oscillation mechanism 34 is driven, causing the recording medium P to oscillate along the media width direction CD (S9).

[0207] Next, the control unit 11 determines whether the cross-state of the registration roller 27 of the recording medium P and the intermediate transfer belt 6 is generated (S11).

[0208] In the event of a cross-state, the control unit 11 performs a second correction control and its correction process on the intermediate transfer belt 6 (S13).

[0209] That is, the control unit 11 determines the corrective movement speed and direction of the intermediate transfer belt 6 based on the output of the first offset detection device 63. Furthermore, the control unit 11 calculates a correction speed B based on the oscillation speed of the recording medium P, the transport length of the recording medium P, the medium width, and the stiffness. Moreover, the control unit 11 drives the steering motor 621 at the corrective movement speed adjusted based on the correction speed B. As a result, the effect of being pulled by the recording medium P can be suppressed, and the position of the intermediate transfer belt 6 in the medium width direction CD can be corrected.

[0210] Then, the control unit 11 causes the process to proceed to step S17.

[0211] On the other hand, if no crossover occurs, the control unit 11 performs a second correction control on the intermediate transfer belt 6 and does not perform correction processing (S15).

[0212] That is, the control unit 11 determines the corrective movement speed and direction of the intermediate transfer belt 6 based on the output of the first offset detection device 63. Moreover, the control unit 11 drives the steering motor 621 at this corrective movement speed.

[0213] Then, the control unit 11 causes the process to proceed to step S17.

[0214] In step S17, the control unit 11 determines whether the end of the recording medium P has passed the alignment roller 27 (S17).

[0215] If the process fails, the control unit 11 returns the process to step S9 and executes the process of steps S9 to S17 again.

[0216] Furthermore, the above operation description explains the processing of steps S9 to S17 for the intermediate transfer belt 6. However, in parallel, the control unit 11 also performs the processing of steps S9 to S17 for the fixing belt 53.

[0217] Then, if it is determined in step S17 that the recording medium P has passed the alignment roller 27, the control unit 11 stops the alignment roller 27 (S19).

[0218] Furthermore, the control unit 11 determines whether the end of the recording medium P has passed through the roller gap of the intermediate transfer belt 6 (S21).

[0219] If the process fails, the control unit 11 returns the process to step S15. The control unit 11 then executes the processes of steps S15 to S19 again, performing the second correction control of the intermediate transfer belt 6.

[0220] In addition, the control unit 11 also performs the processing steps S15 to S19 on the fixing belt 53 until the recording medium P passes through its roller gap.

[0221] Then, if the recording medium P passes through the gap between the intermediate transfer belt 6 and the fixing belt 53, the control unit 11 discharges the recording medium P to the discharge tray 29 (S23).

[0222] Then, the conveying process ends.

[0223] Furthermore, in the above-described motion control during transport, an example is given of performing correction processing on the second correction control when the recording medium P is in a state of crossing, but it is not limited to this.

[0224] For example, sometimes the spanning state of the recording medium P can be known in advance based on the length of the recording medium P. In this case, the correction process of the second correction control can also begin before the recording medium P reaches tapes 6 and 53.

[0225] In this case, the correction process of the second correction control can be started at any time before the recording medium P reaches the belt 6 or 53 from the alignment roller 27.

[0226] Furthermore, it is preferable that the early start execution of the correction process of the second correction control described above can be set by the operation unit 14, for example. In this case, it is preferable that the setting of whether or not the early start execution is performed is stored in the storage unit 12 as a transport condition of the recording medium P. In this case, it is also preferable that setting information for determining the early start timing of the correction process of the second correction control is also included.

[0227] [Technical Effects of the Implementation Method]

[0228] In the image forming apparatus 100 described above, when the control unit 11 performs the first correction control during the generation of the transverse span of the recording medium P, it corrects the second correction control.

[0229] Therefore, the image forming apparatus 100 reduces the impact of alignment wobbling on the belt 6 or 53. Furthermore, it can maintain the belt 6 or 53 in a more reasonable position for better image formation, thus improving image quality.

[0230] The control unit 11 modifies the second correction control based on the oscillation speed of the recording medium P according to the medium oscillation mechanism 34. Therefore, the correction movement speed of the tapes 6 and 53 can be corrected according to the oscillation speed of the recording medium P, and the influence of alignment oscillation can be reduced more effectively.

[0231] The control unit 11 modifies the second correction control based on the transport conditions of the recording medium P. Various transport conditions increase or decrease the influence of the oscillation speed of the recording medium P on the correction movement speed of belts 6 and 53.

[0232] Therefore, the control unit 11 can suppress the influence of the transport conditions of the recording medium P and can more effectively reduce the influence of alignment wobbling on the tapes 6 and 53.

[0233] The control unit 11 obtains the transport conditions of the recording medium P from the image formation setting information. The image formation setting information is stored in the storage unit 12. Therefore, by referring to the storage unit 12, the control unit 11 can more effectively reduce the impact of alignment wobbling on the tapes 6 and 53.

[0234] In addition, the transport conditions of the recording medium P can be obtained from the outside without prior input.

[0235] The control unit 11 obtains the transport conditions of the recording medium P from the media sensor 33, which detects the transported recording medium P. Therefore, the transport conditions of the recording medium P are obtained from the outside, without the need for prior input.

[0236] The control unit 11 determines the correction amount for the second correction control based on the oscillation speed of the recording medium P according to the medium oscillation mechanism 34 and the size of the recording medium P. Therefore, by making a more reasonable correction to the correction movement speed of the belts 6 and 53 that varies according to these factors, the influence of alignment oscillation can be reduced more effectively.

[0237] The control unit 11 determines the correction amount for the second correction control based on the oscillation speed of the recording medium P according to the medium oscillation mechanism 34 and the stiffness of the recording medium P. Therefore, by making a more reasonable correction to the correction movement speed of the belts 6 and 53 that varies according to these factors, the influence of alignment oscillation can be reduced more effectively.

[0238] The control unit 11 determines the correction amount for the second correction control based on the oscillation speed of the recording medium P according to the media oscillation mechanism 34 and the transport speed of the recording medium P. Therefore, by making a more reasonable correction to the correction movement speed of the belts 6 and 53 that varies according to these factors, the influence of alignment oscillation can be reduced more effectively.

[0239] The control unit 11 considers the swing direction of the recording medium P of the media swing mechanism 34 and the offset direction of the tapes 6 and 53, and determines the correction amount for the second correction control. Therefore, it is possible to precisely correct the correction movement speed of the tapes 6 and 53 based on the combination of these directions. In other words, the image forming apparatus 100 can more effectively reduce the impact of alignment wobbling.

[0240] The control unit 11 can also begin to correct the second correction control before the recording medium P reaches the tapes 6 and 53 if the traversal state of the recording medium P is predicted.

[0241] Therefore, when the alignment swing has a significant impact on belts 6 or 53, it is possible to respond to the situation early and effectively reduce its impact.

[0242] The control unit 11 can also correct the second correction control as the recording medium P passes through tapes 6 and 53.

[0243] Therefore, it is possible to effectively correct the effect of real-time alignment oscillation on bands 6 or 53.

[0244] The intermediate transfer belt 6 is the target of the correction of the moving speed, thus enabling the rationalization of the corrected moving speed of the intermediate transfer belt 6. This allows for efficient transfer during image formation, improving image quality.

[0245] The fixing belt 53 is the target of the correction of the moving speed, thus enabling the rationalization of the corrected moving speed of the fixing belt 53. This allows for efficient fixing during image formation, improving image quality.

[0246] The fixing belt 53 is supported by two shafts, making it susceptible to alignment wobbling. In contrast, the control unit 11 corrects the second correction control, thus quickly reducing the impact of alignment wobbling.

[0247] The intermediate transfer belt 6 is supported by three or more shafts, which reduces the impact of alignment wobbling, but makes it difficult to move the belt 6. In contrast, the control unit 11 corrects the second correction control, thus returning the belt 6, which has moved due to alignment wobbling, to a proper position.

[0248] Since the substrate of belts 6 and 53 is made of polyimide, it has high mechanical strength and excellent heat resistance. Therefore, it can achieve good transfer of intermediate transfer belt 6 and good fixing based on fixing belt 53, thereby improving image quality.

[0249] [other]

[0250] The embodiments of this disclosure have been described above. However, this disclosure is not limited to the embodiments described above. For example, in the embodiments, a constituent element integrally formed from a single component may be replaced by a constituent element divided into multiple components that are interconnected or fixed together. Furthermore, a constituent element formed by connecting multiple components may be replaced by a constituent element integrally formed from a single component. Additionally, the details shown in the embodiments can be appropriately changed without departing from the spirit of the disclosure.

[0251] Furthermore, while the foregoing description disclosed examples of non-volatile memory, hard disks, etc., as computer-readable media for the program of this disclosure, it is not limited to these examples. Other computer-readable media include portable recording media such as CD-ROMs. Additionally, a carrier wave (transmission wave) is also used as the medium for providing data of the program of this disclosure via a communication line.

[0252] Furthermore, the detailed structure and operation of the image forming apparatus can be appropriately modified without departing from the spirit of this disclosure.

Claims

1. An image forming apparatus that forms an image on a recording medium by a plurality of processes, wherein Possessing: a medium swing mechanism that swings the recording medium in a medium width direction intersecting a transport direction of the recording medium; a medium detection section that detects a position of an end portion of the recording medium in the medium width direction; a belt correction mechanism that performs position correction of the belt in the medium width direction, the belt being used to perform one of processes of forming an image on the recording medium; a belt detection section that detects a position of an end portion of the belt in the medium width direction; and a control device that performs first correction control in which the medium swing mechanism is caused to perform correction of the position of the end portion of the recording medium based on detection by the medium detection section, and second correction control in which the belt correction mechanism is caused to perform correction of the position of the end portion of the belt based on detection by the belt detection section, the control device correcting the second correction control when the first correction control is performed in a state in which the recording medium is astride both the medium swing mechanism and the belt.

2. The image forming apparatus according to claim 1, wherein the control device corrects the second correction control based on a swing speed of the recording medium according to the medium swing mechanism.

3. The image forming apparatus according to claim 2, wherein the control device corrects the second correction control based on a transport condition of the recording medium.

4. The image forming apparatus according to claim 3, wherein the transport condition of the recording medium is acquired from setting information of image formation.

5. The image forming apparatus according to claim 3, wherein the transport condition of the recording medium is acquired from a medium detection section that detects the recording medium being transported.

6. The image forming apparatus according to claim 3, wherein the control device determines an amount of correction of the second correction control based on a size of the recording medium included in the transport condition of the recording medium and a swing speed of the recording medium according to the medium swing mechanism.

7. The image forming apparatus according to claim 3, wherein the control device determines an amount of correction of the second correction control based on a rigidity of the recording medium included in the transport condition of the recording medium and a swing speed of the recording medium according to the medium swing mechanism.

8. The image forming apparatus according to claim 3, wherein the control device determines an amount of correction of the second correction control based on a transport speed of the recording medium included in the transport condition of the recording medium and a swing speed of the recording medium according to the medium swing mechanism.

9. The image forming apparatus according to claim 3, wherein the control device determines an amount of correction of the second correction control in consideration of a swing direction of the recording medium according to the medium swing mechanism and a deviation direction of the belt.

10. The image forming apparatus according to claim 1, wherein ​ The control device corrects the second correction control before the recording medium reaches the belt when the first correction control is predicted to be performed in a state in which the recording medium straddles both the medium swing mechanism and the belt.

11. The image forming apparatus according to claim 1, wherein The control device corrects the second correction control during passage of the recording medium through the belt.

12. The image forming apparatus according to claim 1, wherein The belt is a transfer belt that performs a transfer process.

13. The image forming apparatus according to claim 1, wherein The belt is a fixing belt that performs a fixing process.

14. The image forming apparatus according to claim 1, wherein The belt is supported by two shafts.

15. The image forming apparatus according to claim 1, wherein The belt is supported by three or more shafts.

16. The image forming apparatus according to claim 1, wherein The base material of the belt is polyimide.

17. A computer program product, wherein, The image forming apparatus includes a medium swing mechanism that swings a recording medium in a medium width direction intersecting a conveyance direction of the recording medium; a medium sensing unit that senses a position of an end portion of the recording medium in the medium width direction; a belt correction mechanism that corrects a position of a belt in the medium width direction, the belt being used to perform one of processes of forming an image on the recording medium; and a belt sensing unit that senses a position of an end portion of the belt in the medium width direction, The computer program product causes a computer of the image forming apparatus to function as: a function of performing a first correction control in which a position of an end portion of the recording medium is corrected by the medium swing mechanism based on sensing by the medium sensing unit; a function of performing a second correction control in which a position of an end portion of the belt is corrected by the belt correction mechanism based on sensing by the belt sensing unit; and a function of correcting the second correction control when the first correction control is performed in a state in which the recording medium straddles both the medium swing mechanism and the belt. ​

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