JP2018180208A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device that can prevent a reduction in durability of a fixing member and can reliably separate a sheet from the fixing member.SOLUTION: In an image forming apparatus 1, a toner image X formed on a sheet P conveyed along a paper feed path 231 is fixed by a fixing member. The fixing member can freely move along the width direction of the sheet P from among directions orthogonal to the conveyance direction of the sheet P when the sheet P passes through a fixing nip. Adjustment control is performed to feed the sheet P such that while the fixing member moves along the width direction of the sheet P, at least the leading end of the sheet P passes through the fixing nip, or move the fixing member along the width direction of the sheet P while at least the leading end of the sheet P passes through the fixing nip.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus.

  Conventionally, heat and pressure are applied to the sheet on which the toner image has been transferred through the fixing nip of the fixing member, and the toner image is fixed to the sheet. Such a sheet is separated from the fixing member after passing through the fixing nip. However, depending on the type of sheet or the image shape of the toner image, the sheet may not be separated from the fixing member even after passing through the fixing nip, so that a jam may occur in the transport path. Therefore, an image forming apparatus has been proposed in which the separation property of the sheet is improved by providing a peeling member on the downstream side of the fixing nip and causing micro slip between the fixing member and the toner image by the peeling member (for example, , Patent Document 1).

JP 2007-164025 A

  However, in the prior art described in Patent Document 1, since the peeling member and the fixing member are always in sliding contact, the durability of the fixing member may be reduced.

  The present disclosure has been made in view of such a situation, and prevents deterioration in durability of the fixing member and enables paper to be reliably separated from the fixing member.

  An image forming apparatus according to one aspect of the present disclosure includes an image forming unit that forms a toner image on a recording medium conveyed along a sheet passing path, and performs image formation to fix the toner image formed on the recording medium. The apparatus is a fixing member provided in the sheet passing path and forming a fixing nip for fixing the toner image on the recording medium, a driving unit capable of moving the fixing member, and controlling the driving unit And at least one processor for executing a control module, wherein the drive unit has a width of the recording medium in a direction orthogonal to the conveyance direction of the recording medium when the recording medium passes through the fixing nip. The fixing member is movable along the direction, and the control module is configured to move the fixing member along the width direction of the recording medium. To feed the recording medium so that the front end passes through the fixing nip, or when at least the front end of the recording medium passes through the fixing nip in the width direction of the recording medium And adjustment instructions for moving along.

  Further, the adjustment instruction relates to the movement of the fixing member by the driving unit, and when the movement of the recording medium in the width direction is stopped, the adjustment instruction prevents at least the tip of the recording medium from passing through the fixing nip. Is preferred.

  Further, it is preferable that the fixing member is configured of a fixing belt, and the drive unit reciprocates the fixing belt along the width direction of the recording medium.

  Further, the adjustment instruction causes the recording medium to pass so that the reciprocation of the fixing belt is folded back at least one of before or after the leading end of the recording medium passes through the fixing nip. Preferably, at least one of the timing and the return timing of the reciprocation of the fixing belt is adjusted.

  Further, the adjustment instruction is at least one of a timing at which the recording medium is passed and a return timing of the reciprocation of the fixing belt such that the reciprocation of the fixing belt is performed between the sheets of the recording medium. It is preferable to adjust the

  Further, it is preferable that the adjustment instruction is to widen a sheet interval of the recording medium when the fixing belt reciprocates back and forth.

  Further, it is preferable that the control module further includes a setting instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium based on the process speed of the image forming unit. .

  Preferably, the setting instruction is to increase a moving speed for moving the fixing member along the width direction of the recording medium as the process speed of the image forming unit is increased.

  Further, the control module further includes a separation property improvement instruction for increasing micro-slip generated between the fixing member and the recording medium, when the separation property of the recording medium from the fixing member is bad. Is preferred.

  Further, the separation property improvement instruction corresponds to a paper type for setting a moving speed for moving the fixing member along the width direction of the recording medium according to at least one of the paper type and the basis weight of the recording medium. It is preferable that the instructions be included.

  Further, it is preferable that the paper type correspondence instruction is to increase the moving speed for moving the fixing member along the width direction of the recording medium as the basis weight of the recording medium decreases.

  Further, the separation property improvement instruction further includes a coverage response instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium according to the coverage of the recording medium. Is preferred.

  Further, it is preferable that the coverage correspondence instruction is to increase a moving speed for moving the fixing member along the width direction of the recording medium as the coverage of the recording medium becomes higher.

  Further, the separation property improvement instruction includes a margin amount correspondence instruction for setting a moving speed at which the fixing member is moved along the width direction of the recording medium in accordance with the margin amount on the leading end side of the recording medium. It is preferable that it is further included.

  Further, it is preferable that the margin amount correspondence instruction is to increase a moving speed for moving the fixing member along the width direction of the recording medium as the margin amount on the leading end side of the recording medium becomes smaller. .

  The image forming apparatus further comprises a separation assisting member provided on the exit side of the fixing nip for separating the recording medium from the fixing belt, wherein the separation assisting member is a nail provided on the outer peripheral surface side of the fixing belt, It is preferable that at least one of an air jet unit which jets air between the recording medium and the fixing belt is configured.

  According to one aspect of the present disclosure, it is possible to prevent the decrease in the durability of the fixing member and to reliably separate the sheet from the fixing member.

FIG. 1 is a diagram showing an example of the overall configuration of an image forming apparatus 1 according to a first embodiment to which the present disclosure is applied. FIG. 1 is a block diagram of an image forming apparatus 1 according to a first embodiment. FIG. 2 is a view showing an example of the arrangement of a fixing unit 35 according to the first embodiment; FIG. 14 is a view showing an example of the reciprocating motion of the fixing belt 3515 according to the first embodiment. FIG. 10 is a view showing still another configuration example of the fixing unit 35 according to the first embodiment. FIG. 5 is a diagram for explaining an area A in which micro slip occurs on a sheet P according to the first embodiment. FIG. 6 is a view showing an example of the sheet passing timing of the sheet P and the movement range of the fixing belt 3515 according to the first embodiment. FIG. 8 is a view showing an example of the relationship between the basis weight and the moving speed v of the fixing member according to the first embodiment. FIG. 6 is a view showing an example of the relationship between coverage according to Embodiment 1 and moving speed v of the fixing member. FIG. 6 is a view showing an example of the relationship between the front end margin amount of the sheet P and the moving speed v of the fixing member according to the first embodiment. 7 is a flowchart illustrating an example of control of the fixing unit 35 according to the first embodiment. FIG. 18 is a diagram illustrating another configuration example of the fixing unit 35 according to the second embodiment to which the present disclosure is applied.

Embodiment 1
Hereinafter, embodiments of the present disclosure will be described based on the drawings, but the present disclosure is not limited to the following embodiments. Note that as used in the description of the embodiments of the present disclosure, “consists”, “consists”, “includes”, “includes”, “haves”, “includes” or any other of them. Synonyms are intended to cover non-exclusive inclusive relationships. For example, a process, method, article or apparatus that includes a list of elements is not necessarily limited to only those elements, and other elements not explicitly listed or otherwise inherent may Such processes, methods, articles or devices may be included. Furthermore, unless explicitly stated otherwise, "or" is inclusive and not exclusive. For example, "condition A or B" is satisfied in any case where A is present and B is absent, A is absent and B is present, and both A and B are present. It is.

  The present disclosure also relates to an apparatus for performing the operations described herein. The apparatus may be specially constructed according to the required purpose, or may be constructed on a general purpose computer selectively activated or reconfigured by a computer program stored in the computer.

  Also, the algorithms described herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used with the program according to the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the required method steps. The structure required for these various systems will be apparent from the following description. Furthermore, the present disclosure does not rely on any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the present disclosure as described herein.

  FIG. 1 is a view showing an example of the overall configuration of an image forming apparatus 1 according to a first embodiment to which the present disclosure is applied. FIG. 2 is a block diagram of the image forming apparatus 1 according to the first embodiment. FIG. 3 is a view showing an example of the arrangement of the fixing unit 35 according to the first embodiment. FIG. 4 is a view showing an example of the reciprocating motion of the fixing belt 3515 according to the first embodiment. FIG. 5 is a view showing still another configuration example of the fixing unit 35 according to the first embodiment.

  As shown in FIG. 1, the image forming apparatus 1 includes a reading unit 10, a sheet feeding unit 20, and an image forming unit 30. The sheet feeding unit 20 includes a sheet feeding cassette 21 and a sheet feeding and conveying unit 22. The paper feed cassette 21 stores recording media of different paper sizes. The sheet feeding and conveying unit 22 includes various rollers, and conveys the recording medium stored in the sheet feeding cassette 21 to the image forming position of the image forming unit 30. The recording medium is, for example, a sheet P or a long sheet. The paper P is, for example, single-cut paper, glossy paper, or a continuous paper or the like in which holes are formed at fixed pitches at both ends. The image forming unit 30 includes an exposure device 31, a photosensitive drum 32, a developing device 33, a transfer belt 34, and a fixing unit 35. The image forming unit 30 supplies toners of different colors to the photosensitive drum 32 by the exposure device 31 based on the image data of the document read by the reading unit 10 and develops the same. The image forming unit 30 transfers the toner image X developed on the photosensitive drum 32 by the transfer belt 34 onto the recording medium supplied from the paper feeding unit 20. The image forming unit 30 fuses the toner of the toner image X transferred to the recording medium by the fixing unit 35, whereby the toner image X is fixed on the recording medium.

  The reading unit 10 includes an ADF 10 a and an image reading unit 10 b. The ADF 10 a includes a document tray 11, a sheet discharge tray 12, a sheet passing path 13, a contact image sensor 14, a density reference member 15 and the like. The density reference member 15 is used at the time of shading correction of the ADF 10 a. The image reading unit 10 b includes an original illumination unit 42, a reflection mirror 43, a condensing lens 44, a line image sensor 45, and a platen glass 46. The reading unit 10 separates the document set in the document tray 11 one by one and feeds it out, and conveys it in the sub-scanning direction along the sheet passing path 13 where the contact type image sensor 14 is disposed, and discharges the document. The sheet is discharged to the tray 12. The document illumination unit 42 includes a lamp 42 a and a mirror 42 b. While the document is conveyed in the sub-scanning direction along the sheet passage path 13, the reading operation in line units in the main scanning direction is repeatedly performed by the document illumination unit 42, the reflection mirror 43, the condenser lens 44, and the line image sensor 45. Be done. A white reference plate 41 is attached close to and facing the image reading unit 10b. The white reference plate 41 is used at the time of shading correction of the image reading unit 10b. The lamp 42 a is turned on in a state where there is no document between the image reading unit 10 b and the white reference plate 41, and the light is emitted to the white reference plate 41. The light including the reflected light of the white reference plate 41 is received by the line image sensor 45 via the mirror 42 b, the reflection mirror 43, and the condenser lens 44.

  As shown in FIG. 2, the image forming apparatus 1 includes a main circuit 110, an ADF 10a, an image reading unit 10b, an image forming unit 30 outlined above, a sheet feeding unit 20, and an operation panel 160. A sensor 201, a sensor 202, and a sensor 203 are included, and they are connected via a bus 101. The ADF 10 a is for transporting a document to the image reading unit 10 b. The image reading unit 10 b reads an original conveyed by the ADF 10 a. The image forming unit 30 forms an image on a recording medium such as a sheet P based on image data of a document read by the image reading unit 10b. The sheet feeding unit 20 supplies a recording medium such as a sheet P to the image forming unit 30.

  The operation panel 160 is provided on the upper surface side of the image forming apparatus 1 and includes a display unit 161 and an operation unit 163. The operation panel 160 is used to display contents related to various modes and receive operations. The display unit 161 is a display device, and includes, for example, a liquid crystal display device. The display unit 161 displays an instruction menu for the user, information on image data of a document read by the image reading unit 10b, information on various modes, and the like.

  The operation unit 163 receives an instruction from the user's operation. Operation unit 163 includes hard key unit 167. Hard key portion 167 is composed of a plurality of keys. Each of the plurality of keys receives input of data such as various instructions, characters, and numbers. Operation unit 163 includes touch panel 165. The touch panel 165 is provided on the display unit 161, and detects coordinates corresponding to a place where the display screen of the display unit 161 is touched.

  The main circuit 110 includes one or more processors 113 and an interface unit 111. The one or more processors 113 are connected to the ADF 10 a, the image reading unit 10 b, the image forming unit 30, the sheet feeding unit 20, and the operation panel 160, and control the image forming apparatus 1. The memory 115 stores, via the memory controller 114, data necessary for executing one or more control modules 1151 executed by the one or more processors 113 or the one or more control modules 1151. The interface unit 111 receives various data or instructions transmitted from the outside, and transmits the processing result of one or more processors 113 to the outside.

  The fixing unit 35 is provided in a sheet passing path 231 formed by the conveyance guides 221 and 222, and forms a fixing nip for fixing the toner image X to the sheet P. The fixing unit 35 includes an upper fixing unit 351 and a lower fixing unit. And 353. The upper fixing unit 351 supplies heat to the toner image X via the fixing nip. The lower fixing unit 353 is provided to face the upper fixing unit 351, and applies pressure to the toner image X through the fixing nip.

  Specifically, as shown in FIG. 3, the upper fixing unit 351 includes a heating roller 3512, an upper pressure roller 3511, and a fixing belt 3515. The lower fixing unit 353 includes a lower pressure roller 3531. The heating roller 3512 includes a fixing heater 3516, and the fixing heater 3516 can be supplied with heat by being controlled to be either in the ON state or in the OFF state. The upper pressure roller 3511 rotates in the rotation direction S_1 in conjunction with the heating roller 3512, and forms a fixing nip. The lower pressure roller 3531 is provided to face the upper pressure roller 3511, forms a fixing nip with the upper pressure roller 3511, and rotates in the rotation direction T_1. The fixing belt 3515 is wound around the heating roller 3512 and the upper pressure roller 3511. The sensor 201 is provided on the fixing nip exit side to detect the passage of the sheet P. For example, the sensor 201 outputs a sheet passing signal in response to the detection of the passage of the sheet P.

  Further, as shown in FIG. 4, the fixing belt 3515 has a direction N along the width direction of the sheet P among the directions orthogonal to the conveyance direction of the sheet P when the sheet P passes the fixing nip by the drive unit 355. It is configured to be freely movable. Specifically, the drive unit 355 reciprocates the fixing belt 3515 along the direction N. For example, at least one sensor 202 is provided at each end of the heating roller 3512, and the sensor 202 detects the movement of the fixing belt 3515. The movement of the fixing belt 3515 may be controlled by inclining the heating roller 3512 by the drive unit 355 to the inclination angle θ + or θ− with reference to the inclination reference angle θ0. Further, as shown in FIG. 5, the fixing unit 35 includes a fixing roller 3513 that rotates in the rotation direction S_2 as the upper fixing unit 351, and includes a pressure roller 3532 that rotates in the rotation direction T_2 as the lower fixing unit 353. It is also good. In this case, the reciprocation control of the fixing roller 3513 may be realized by moving the member supporting the shaft of the fixing roller 3513 along the axial direction by the driving unit 355 including the fixing roller 3513.

  When the fixing belt 3515 and the fixing roller 3513 are collectively referred to, they are referred to as a fixing member. That is, the fixing member includes the fixing belt 3515 or the fixing roller 3513. The fixing member is movable by the drive unit 355.

  Specifically, the reciprocation control of the fixing member is performed by one or more processors 113 that execute the control module 1151 stored in the memory 115. The control module 1151 causes the sheet P to pass such that at least the front end of the sheet P passes through the fixing nip when the fixing member moves in the width direction of the sheet P, or at least the front end of the sheet P Includes adjustment instructions for moving the fixing member along the width direction of the sheet P when passing through the fixing nip. That is, the positional relationship between the sheet P and the fixing member may be relatively shifted along the direction N of movement of the fixing member. Since the positional relationship between the sheet P and the fixing member is relatively shifted along the direction N of movement of the fixing member, microslip corresponding to the moving velocity v in the direction N of movement of the fixing member is generated. The separation is improved by reducing the adhesion between the toner image X formed on the sheet P and the fixing member. Therefore, the adhesion between the toner image X and the fixing member is weakened according to the micro slip amount δ, so that the situation in which at least the leading edge of the sheet P is not separated can be avoided.

  FIG. 6 is a view for explaining an area A in which the micro slip occurs on the sheet P according to the first embodiment. The pattern I is to cause micro slip on the leading end side of the sheet P. The pattern II is to cause microslip on the entire sheet P. The pattern III is to generate micro slips on the leading end side of the sheet P and in the middle of the sheet P. The pattern IV is to cause microslip from the middle of the sheet P to the rear end side. In order to properly separate the sheet P from the fixing member, at least the leading edge of the sheet P needs to be separated. However, among the patterns I to IV, since the pattern IV has no microslip at the front end of the paper P, the adhesion of the front end of the paper P is not reduced, and the purpose of properly separating the paper P from the fixing member This can not be achieved, and the sheet P can not be separated from the fixing member. On the other hand, among the patterns I to IV, since any of the patterns I to III can cause microslip on the leading end side of the sheet P, as described above, between the toner image X and the fixing member Reduced adhesion results in better separation. As a result, the adhesion between the toner image X and the fixing member is weakened, so that the sheet P can be separated from the fixing member. However, the fixing member is reciprocally controlled. Therefore, when the fixing member is folded back, the moving speed v of the fixing member along the direction N of movement is 0, so micro-slip along the direction N may not occur. At this time, when the leading end of the sheet P passes through the fixing nip, microslip does not occur, and the sheet P may be wound around the fixing member, causing a jam in the sheet passage path 231.

  Therefore, the adjustment instruction is to avoid that at least the front end of the sheet P passes through the fixing nip when the fixing member is folded back. Specifically, the adjustment instruction is a timing at which the sheet P is passed so that the reciprocation of the fixing belt 3515 is folded back at least before or after the leading end of the sheet P passes through the fixing nip. And, at least one of the return timing of the reciprocation of the fixing belt 3515 is adjusted. Specifically, as shown in FIG. 4, by providing the sensor 203 upstream of the position where the fixing nip is formed in the sheet passing direction M of the sheet P, the timing at which the sensor 203 passes the sheet P is detected. it can. The sheet P passes through the fixing nip based on the measurement start time t0 when the sheet P passes the sensor 203, the measured distance x0 from the position where the sensor 203 detects the sheet P to the fixing nip, and the conveyance speed V of the sheet P. A passing time t which is a length of time including the passing timing to be obtained can be obtained by measurement start time t0 + measured distance x0 / conveyance velocity V. If such a passing time t is determined, the sheet P passes through so that the reciprocation of the fixing belt 3515 is folded back at least either before or after the leading edge of the sheet P passes through the fixing nip. It is possible to adjust at least one of the timing at which the fixing belt 3515 is moved and the return timing of the reciprocation of the fixing belt 3515. The timing at which the leading end of the sheet P passes through the fixing nip may be obtained at the timing when the image forming unit 30 forms an image on the sheet P. For example, as shown in FIG. 1, the measurement start time t1 when the leading edge of the sheet P passes the transfer nip of the secondary transfer roller 341 and the measurement distance from the transfer nip of the secondary transfer roller 341 to the fixing nip of the fixing unit 35 Based on x1 and the process velocity Vp, the transit time t can be determined by measurement start time t1 + measurement distance x1 / process velocity Vp.

  The adjustment instruction adjusts at least one of the timing for passing the sheet P and the return timing of the reciprocation of the fixing belt 3515 so that the reciprocation of the fixing belt 3515 is reversed between the sheets of paper P. May be FIG. 7 is a view showing an example of the sheet passing timing of the sheet P and the movement range of the fixing belt 3515 according to the first embodiment. As shown in FIG. 7, when the reciprocation of the fixing belt 3515 is folded back, the moving speed v of the fixing belt 3515 along the direction N of movement is zero. In such a case, when the sheet P is fed, since micro slip does not occur, there is a possibility that jam may occur in the sheet passing path 231. Therefore, a time during which the moving speed v of the fixing belt 3515 along the direction N is approximately 0 is set as the paper non-passing possible time, and when it is the sheet non-permissible time, the sheet P does not pass through the fixing nip. Further, the adjustment instruction may extend the sheet interval of the sheet P when the fixing belt 3515 is folded back and forth. Further, as shown in FIG. 7, for example, adjustment is made so that the timing when the interval between the fifth sheet and the sixth sheet of the sheet P is extended and the return timing of the reciprocation of the fixing belt 3515 coincide with each other. . The moving range of the fixing belt 3515 is the upper limit value and the lower limit value, and each corresponds to the moving limit value. The movement limit value may be set based on, for example, the positions of the sensors 202 shown in FIG. 4 that are detected on the outer side.

  By the way, there is a correlation between the process speed Vp and the microslip amount δ, and when control is made to make the microslip amount δ constant, fixing is performed along the process speed Vp and the direction N of movement of the fixing member. There is a correlation with the moving speed v at which the member is moved. Therefore, the control module 1151 preferably includes a setting instruction for setting a moving speed v for moving the fixing member along the direction N based on the process speed Vp. The setting instruction preferably increases the moving speed v for moving the fixing member along the direction N as the process speed Vp increases. Specifically, the moving speed v for moving the fixing member along the direction N of movement of the fixing member is preferably 0.05% to 1% of the process speed Vp, and more preferably 0.1% to 0.4%. It is. More specifically, the microslip amount δ given to the sheet P, in particular, the microslip amount δ given to the toner image X, is a passing time ti which is the length of time for which the leading edge of the sheet P passes through the fixing nip. And the moving speed v for moving the fixing member along the direction N of movement of the fixing member, the microslip amount δ = passing time ti × moving speed v. Further, based on the process speed Vp and the fixing nip width L, passing time ti = fixing nip width L / process speed Vp, so the micro slip amount δ = (fixing nip width L × moving speed v) / process speed Vp It becomes. That is, as the process speed Vp increases, the microslip amount δ decreases. Therefore, it is preferable to increase the moving speed v following the increase of the process speed Vp. The microslip amount δ is preferably generated between the toner image X and the fixing member. As a result, the adhesion between the toner image X and the fixing member is reduced, and the separability is improved.

  Further, if the moving speed v for moving the fixing member along the direction N is too low, microslip does not occur, and improvement in the separation of the sheet P from the fixing member can not be realized. On the other hand, if the moving speed v of moving the fixing member along the direction N of movement of the fixing member is too fast, there may be a problem such as an image defect. Therefore, it is preferable that the control module 1151 includes a separability improvement instruction for increasing the microslip amount δ generated between the fixing member and the sheet P when the separability of the sheet P from the fixing member is bad. The separation property improvement instruction preferably includes a sheet type corresponding instruction for setting a moving speed v for moving the fixing member along the direction N according to at least one of the sheet type and the basis weight of the sheet P. FIG. 8 is a view showing an example of the relationship between the basis weight and the moving speed v of the fixing member according to the first embodiment. As shown in FIG. 8, the paper type correspondence instruction is to increase the moving speed v for moving the fixing member along the direction N as the basis weight of the paper P corresponding to the paper type of the paper P decreases. is there. Preferably, the separation property improvement instruction includes a coverage response instruction for setting a moving speed v for moving the fixing member along the direction N according to the coverage of the sheet P. FIG. 9 is a view showing an example of the relationship between the coverage according to the first embodiment and the moving speed v of the fixing member. As shown in FIG. 9, the coverage correspondence instruction is to increase the moving speed v for moving the fixing member along the direction N as the coverage of the sheet P becomes higher. Further, the separation property improvement instruction includes a margin amount correspondence instruction for setting a moving speed v for moving the fixing member along the direction N of movement of the fixing member according to the margin amount on the leading end side of the sheet P. Is preferred. FIG. 10 is a view showing an example of the relationship between the front end margin amount of the sheet P and the moving speed v of the fixing member according to the first embodiment. As shown in FIG. 10, the margin amount correspondence instruction increases the moving speed v for moving the fixing member along the direction N of the movement of the fixing member as the margin amount on the leading end side of the sheet P decreases. is there.

  FIG. 11 is a flowchart illustrating an example of control of the fixing unit 35 according to the first embodiment. First, as a premise of processing, it is assumed that the position of the fixing belt 3515 in the direction N is at the initial position before the movement of the fixing belt 3515 is started. The initial position is at the center of the movable range of the fixing belt 3515. In step S11, movement of the fixing belt 3515 is started along the direction N of movement of the fixing belt 3515. In step S12, it is determined whether the fixing belt 3515 exceeds the movement limit value while the leading end of the next sheet P passes the fixing nip. If it is determined that the fixing belt 3515 exceeds the movement limit value before the leading end of the next sheet P passes the fixing nip (step S12; Y), the process proceeds to step S17. In step S17, the moving direction of the fixing belt 3515 is changed, and the process returns to step S11. On the other hand, if it is determined that the fixing belt 3515 does not exceed the movement limit value before the leading edge of the next sheet P passes the fixing nip (step S12; N), the process proceeds to step S13. In step S13, the sheet P is passed. In step S14, it is determined whether the leading edge of the sheet P has passed the fixing nip. If it is determined that the leading end of the sheet P has passed the fixing nip (step S14; Y), the process proceeds to step S15. On the other hand, when it is determined that the leading end of the sheet P does not pass through the fixing nip (step S14; N), the process of step S14 is maintained.

  In step S15, it is determined whether the sheet P of the final page has been passed. When it is determined that the sheet P of the final page has been passed (step S15; Y), the process proceeds to step S16. In step S16, the position in the direction N of movement of the fixing belt 3515 is returned to the initial position, and the movement of the fixing belt 3515 along the direction N in the movement N of the movement of the fixing belt 3515 is stopped. On the other hand, when it is determined that the sheet P of the final page is not passed (step S15; N), the process returns to the process of step S12.

  From the above description, according to the image forming apparatus 1 to which the present disclosure is applied, the sheet P is moved such that at least the front end of the sheet P passes through the fixing nip when the fixing member is moving along the width direction of the sheet P. Or the fixing member is moved along the width direction of the sheet P when at least the leading end of the sheet P passes through the fixing nip. Thereby, the positional relationship between the sheet P and the fixing member is relatively shifted along the direction N of movement of the fixing member at least at the front end of the sheet P, and the toner image X formed on the sheet P and the fixing member Micro slip occurs during the Further, the adhesion between the toner image X and the fixing member is weakened according to the microslip amount δ. Thus, the sheet P can be reliably separated from the fixing member.

  Further, in the image forming apparatus 1, the inner peripheral side of the fixing belt 3515 does not slide with the fixing member. Therefore, the fixing belt 3515 is not deteriorated due to the sliding with the fixing member.

  Therefore, the decrease in durability of the fixing member can be prevented, and the sheet P can be reliably separated from the fixing member.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, regarding movement of the fixing member by the drive unit 355, movement of the sheet P in the width direction, that is, movement of the fixing member in the direction N stops moving. At least the tip of P is to avoid passing through the fixing nip. Therefore, when the fixing member is folded back, at least the leading end of the sheet P does not pass through the fixing nip. Therefore, the sheet P can be reliably separated from the fixing member.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the fixing belt 3515 is reciprocated along the direction N, so that relative positional deviation between the fixing belt 3515 and the toner image X can be obtained. Since the image can be generated, microslip can be easily generated between the fixing belt 3515 and the toner image X.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the sheet is reciprocated so that the reciprocation of the fixing belt 3515 is performed at least one before or after the leading end of the sheet P passes through the fixing nip. By adjusting at least one of the timing of passing P and the return timing of the reciprocating movement of the fixing belt 3515, the fixing belt 3515 is turned back when the leading end of the sheet P is not passing through the fixing nip. When the leading end of the sheet P is passing through the fixing nip, the fixing belt 3515 moves in the direction N of movement. Therefore, the leading end of the sheet P does not pass through the fixing nip at the timing when the direction N of movement of the fixing belt 3515 switches, and the tip of the sheet P passes through the fixing nip while the fixing belt 3515 moves in the direction N of movement. Do. Therefore, since relative positional deviation between the sheet P and the fixing belt 3515 can be generated in the fixing nip, micro-slip is surely generated between the fixing belt 3515 and the sheet P in the fixing nip. Can.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the timing for passing the sheet P and the reciprocation of the fixing belt 3515 are performed so that the reciprocation of the fixing belt 3515 is folded back between the sheets of the paper P. By adjusting at least one of the folding timings, as in the pattern II of FIG. 6, it is possible to generate micro slips over the entire length of the paper P, and separation can be further improved. .

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the fixing belt 3515 is folded back with room by widening the sheet interval of the sheet P when the fixing belt 3515 is folded back and forth. Therefore, when the fixing belt 3515 does not move along the direction N of movement when the fixing belt 3515 is folded back, the situation in which the leading end of the sheet P passes through the fixing nip can be more reliably avoided. Can.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, when the moving speed v for moving the fixing member along the width direction of the sheet P is too slow, microslip does not occur, and the sheet P is separated from the fixing member. I can not do it. On the other hand, when the moving speed v for moving the fixing member along the width direction of the sheet P is too fast, the toner image X formed on the sheet P may have a defect such as an image defect. Therefore, the image forming apparatus 1 sets the moving speed v for moving the fixing member along the width direction of the sheet P based on the process speed Vp of the image forming unit 30. Therefore, since the moving speed v for moving the fixing member along the width direction of the sheet P can be appropriately set, the sheet P can be stably separated from the fixing member.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, as the moving speed v for moving the fixing member along the width direction of the sheet P increases, the micro slip amount δ increases. As the process speed Vp of the image forming unit 30 increases, the microslip amount δ decreases. Therefore, the image forming apparatus 1 appropriately adjusts the micro-slip amount δ by increasing the moving speed v for moving the fixing member along the width direction of the sheet P as the process speed Vp of the image forming unit 30 increases. The sheet P can be stably separated from the fixing member.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, when the separation property of the sheet P from the fixing member is poor, the sheet is increased by increasing the micro slip amount δ generated between the fixing member and the toner image X. Since the adhesion between P and the fixing member can be further weakened, the sheet P can be separated more surely from the fixing member.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the moving speed v for moving the fixing member along the width direction of the sheet P is set according to at least one of the sheet type and the basis weight of the sheet P. Thus, even if the sheet type or the basis weight of the sheet P is poor, the moving speed v for moving the fixing member along the width direction of the sheet P can be appropriately set, so the separation property of the sheet P is improved. It can be done.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, separation of the sheet P is performed by increasing the moving speed v for moving the fixing member along the width direction of the sheet P as the basis weight of the sheet P decreases. Since the microslip amount δ generated between the fixing member and the toner image X can be increased even if the sheet type is poor, the separating property of the sheet P can be improved.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the moving speed v for moving the fixing member along the width direction of the sheet P is set according to the coverage of the sheet P, thereby forming the sheet P Since the moving speed v for moving the fixing member along the width direction of the sheet P can be appropriately set even if the separation property of the sheet P is poor due to the toner amount of the toner image X being performed, the sheet P separation property is improved. It can be improved.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, separation of the sheet P is performed by increasing the moving speed v for moving the fixing member along the width direction of the sheet P as the coverage of the sheet P increases. Since the microslip amount δ generated between the fixing member and the toner image X can be increased even if the toner amount to the extent that the property is deteriorated adheres to the sheet P, the separation property of the sheet P is improved. Can.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the moving speed v for moving the fixing member along the width direction of the sheet P is set according to the margin amount on the front end side of the sheet P Since the microslip amount δ generated between the fixing member and the toner image X can be increased even if the separability of the paper P is poor due to the margin constituting the paper P, the separability of the paper P is improved. Can.

  Further, according to the image forming apparatus 1 to which the present disclosure is applied, the sheet is moved by moving the fixing member along the width direction of the sheet P as the margin amount on the leading end side of the sheet P decreases. Even if the paper P has such a small margin that the separability of P is deteriorated, the microslip amount δ generated between the fixing member and the toner image X can be increased, so the separability of the paper P can be improved. Can.

Embodiment 2
FIG. 12 is a diagram illustrating another configuration example of the fixing unit 35 according to the second embodiment. In the second embodiment, the configuration for causing the micro slip at the leading end of the sheet P is the same configuration and function as the first embodiment. In the second embodiment, descriptions of configurations and functions similar to those of the first embodiment will be omitted. In the second embodiment, in addition to the configuration of the first embodiment, at least one of the configuration of the claw 241 and the air injection unit 242 is provided. In the example of FIG. 12, the claw 241 or the air injection unit 242 is provided on the exit side of the fixing nip, as shown in the enlarged area Z of the exit side of the fixing nip. The claws 241 are provided in the vicinity of the fixing nip exit and function as a separation assisting member for separating the sheet P from the fixing belt 3515. The claws 241 are provided so as to be able to abut on the outer peripheral side of the fixing belt 3515 or via a minute gap, and are formed by a triangular member 241A whose cross section becomes thinner toward the front end side which is the fixing belt 3515 side. The support member 241C is swingably supported by a support shaft 241B provided at a rear end opposite to the front end side as a rotation axis.

  The air injection unit 242 guides the fan 242A for delivering air having a preset air volume, and the air sent from the fan 242A to be jetted between the sheet P coming out of the fixing nip and the fixing belt 3515. A nozzle portion 242 B is provided and functions as a separation assisting member for separating the sheet P from the fixing belt 3515. The opening at the tip of the nozzle portion 242B is formed in an elongated shape along the direction orthogonal to the rotation direction S_1 of the fixing belt 3515, and the elongated direction of the elongated shape corresponds to the axial direction of the upper pressure roller 3511, ie, the fixing nip It is provided almost parallel to the Therefore, the air jet unit 242 can uniformly jet air to the sheet P which has passed through the fixing nip. The air volume of the air injected from the nozzle portion 242B can be adjusted by controlling the value of the current supplied to the fan 242A and changing the rotation speed of the fan 242A.

  That is, in the second embodiment, in addition to the configuration in which the micro slip is generated at the leading end of the sheet P as described in the first embodiment, the air jet unit 242 separates the sheet P from the fixing member by blowing air onto the sheet P. Alternatively, a separation assisting member such as a claw 241 for separating the sheet P from the fixing member is provided on the outer peripheral surface side of the fixing nip. The separation assisting member further improves the separation of the sheet P when the leading edge of the sheet P is separated from the fixing member. As a result, even if microslip does not occur on the entire surface of the sheet P as in the pattern II of FIG. 6, for example, even in the case of causing microslip only on the leading edge of the sheet P as in the case of the pattern I of FIG. The separability can be further improved, and the paper P can be more reliably separated from the fixing member.

  As mentioned above, although the image forming apparatus 1 which is one aspect of this indication was explained based on an embodiment, this indication is not limited to this, Even if it changes in the range which does not deviate from the meaning of this indication Good.

  For example, although an example in which the reciprocation of the fixing belt 3515 is realized by controlling the inclination of the fixing member by controlling the inclination of the heating roller 3512 has been described, the present invention is not particularly limited thereto. For example, although not shown, adjustment may be performed by the inclination of another roller included in the fixing belt 3515.

  The upper fixing unit 351 includes the heating roller 3512 and the upper pressing roller 3511, and the lower fixing unit 353 includes the lower pressing roller 3531. However, the present invention is not limited thereto. . For example, in the fixing unit 35 including the fixing belt 3515, one that heats without using the heating roller 3512, one that forms a fixing nip with, for example, a pad instead of the upper pressure roller 3511, or The pad may form a fixing nip.

  The series of processes described above can be executed by hardware or can be executed by software. When a series of processes are to be executed by software, the program constituting the software installs various programs, and from a recording medium for recording the programs on a computer capable of executing various functions, or , Etc. via the Internet.

  In addition, although an example using the memory 115 as a recording medium for storing the program executed by the processor 113 has been described, the present invention is not limited thereto, and an optical disc, an IC card, an optical card, a mask ROM, an EPROM (Erasable Disc), and an EEPROM (Electrically) It may be a semiconductor memory such as EPROM).

  Here, the sheet interval of the sheets P means the interval between one sheet P and one sheet P conveyed next to the one sheet P.

1 image forming apparatus, 10 reading unit, 10a ADF, 10b image reading unit,
11 document tray, 12 paper output tray, 13 paper path,
14 contact image sensors, 15 density reference members,
Reference Signs List 20 sheet feeding unit, 21 sheet feeding cassette, 22 sheet feeding and conveying unit 201, 202, 203 sensor 221, 222 conveyance guide, 231 sheet passing path 241 claw, 241 A triangular member, 241 B support shaft, 241 C support member 242 air injection unit 242A fan 242B nozzle unit 30 image forming unit 31 exposure device 32 photosensitive drum 33 developing device
34 transfer belt, 341 secondary transfer roller 35 fixing unit, 351 upper fixing unit, 353 lower fixing unit 355 driving unit, 3511 upper pressure roller, 3512 heating roller 3513 fixing roller, 3515 fixing belt, 3516 fixing heater 3531 under Pressure roller, 3532 pressure roller 41 white reference plate, 42 document illumination unit, 42a lamp, 42b mirror 43 reflection mirror, 44 condensing lens,
45 line image sensor, 46 platen glass,
DESCRIPTION OF SYMBOLS 101 bus, 110 main circuit, 111 interface part 113 processor, 114 memory controller, 115 memory 1151 control module 201, 202, 203 sensor 160 operation panel, 161 display part, 163 operation part 165 touch panel, 167 hard key part A area, I , II, III, IV pattern, X toner image, Z area M sheet passing direction, N direction, P sheet, S_1, S_2, T_1, T_2 rotation direction v moving speed, V conveying speed, Vp process speed L fixing nip width, σ Minute gap t, ti passage time, t0, t1 measurement start time, x0, x1 measurement distance δ micro slip amount, θ0 inclination reference angle, θ +, θ− inclination angle

Claims (16)

An image forming apparatus comprising: an image forming unit that forms a toner image on a recording medium conveyed along a sheet passing path; and fixing the toner image formed on the recording medium,
A fixing member provided in the sheet passing path and forming a fixing nip for fixing the toner image on the recording medium;
A driving unit capable of moving the fixing member;
One or more processors that execute control modules that control the drives;
Equipped with
The drive unit is
When the recording medium passes through the fixing nip, the recording medium along the width direction of the recording medium among the directions orthogonal to the conveyance direction of the recording medium.
The fixing member is movable;
The control module
For passing the recording medium so that at least the front end of the recording medium passes through the fixing nip when the fixing member moves along the width direction of the recording medium, or at least the recording medium An adjustment instruction for moving the fixing member along the width direction of the recording medium when the leading end passes through the fixing nip;
Including
Image forming apparatus. The adjustment instruction is
With respect to the movement of the fixing member by the drive unit, when the movement of the recording medium in the width direction is stopped, the at least the tip of the recording medium is prevented from passing through the fixing nip.
An image forming apparatus according to claim 1. The fixing member is
It consists of a fixing belt,
The drive unit is
The fixing belt is reciprocally moved along the width direction of the recording medium.
The image forming apparatus according to claim 1. The adjustment instruction is
The timing at which the recording medium is passed and the reciprocation of the fixing belt so that the reciprocation of the fixing belt is folded back at least one before or after the leading end of the recording medium passes the fixing nip. Adjusting at least one of the return timings of movement;
An image forming apparatus according to claim 3. The adjustment instruction is
The timing at which the recording medium is fed and / or the timing at which the fixing belt reciprocates is adjusted may be adjusted so that the reciprocation of the fixing belt is reversed between sheets of the recording medium.
The image forming apparatus according to claim 4. The adjustment instruction is
The sheet interval of the recording medium is expanded when the fixing belt reciprocates back and forth.
An image forming apparatus according to claim 5. The control module
A setting instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium based on the process speed of the image forming unit;
Further including,
The image forming apparatus according to any one of claims 1 to 6. The setting instruction is
The moving speed of moving the fixing member along the width direction of the recording medium may be increased as the process speed of the image forming unit is increased.
The image forming apparatus according to claim 7. The control module
An instruction to improve separability to increase micro slip occurring between the fixing member and the recording medium when the separability of the recording medium from the fixing member is poor.
Further including,
The image forming apparatus according to any one of claims 1 to 8. The separation improvement instruction is
A sheet type corresponding instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium according to at least one of the sheet type and the basis weight of the recording medium;
Including
The image forming apparatus according to claim 9. The paper type correspondence instruction is
The moving speed for moving the fixing member along the width direction of the recording medium is increased as the basis weight of the recording medium decreases.
The image forming apparatus according to claim 10. The separation improvement instruction is
A coverage response instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium according to the coverage of the recording medium;
Further including,
The image forming apparatus according to any one of claims 9 to 11. The coverage correspondence instruction is
The moving speed of moving the fixing member along the width direction of the recording medium is increased as the coverage of the recording medium is increased.
An image forming apparatus according to claim 12. The separation improvement instruction is
A margin amount corresponding instruction for setting a moving speed for moving the fixing member along the width direction of the recording medium according to the margin amount on the leading end side of the recording medium.
Further including,
The image forming apparatus according to any one of claims 9 to 13. The margin amount corresponding instruction is
The moving speed for moving the fixing member along the width direction of the recording medium is increased as the margin amount at the leading end side of the recording medium decreases.
The image forming apparatus according to claim 14. A separation assisting member provided on the exit side of the fixing nip and separating the recording medium from the fixing belt;
And further
The separation assisting member is
At least one of a claw provided on the outer peripheral surface side of the fixing belt, and an air injection unit for injecting air between the recording medium and the fixing belt.
The image forming apparatus according to any one of claims 3 to 6.

Images