JP2011227137A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can easily removes a transferred material jammed.SOLUTION: The image forming apparatus includes: a conveyance path L that conveys a transferred material; an image forming section 40 that forms a toner image on the transferred material conveyed on the conveyance path L; a heating rotating body 61 that heats the transferred body; a pressure rotating body 62 that forms a fixing nip N between itself and the heating rotating body 61 to pressurize the transferred material conveyed to the fixing nip N; and a nip pressure adjusting section that adjusts a nip pressure of the fixing nip. The image forming apparatus also includes: a fixing section 60 that is arranged on the downstream side of the transferred material in the conveying direction; a detecting section that detects jam of the transferred material conveyed on the conveyance path L; and a control section that controls the nip pressure adjusting section so as to change the pressure of the fixing nip N in accordance with the jam position of the transferred material when the detecting section detects the jam of the transferred material.

Description

  The present invention relates to an image forming apparatus that forms an image on a transfer material such as paper.

  Some image forming apparatuses include an image forming unit that forms a toner image on a sheet (transfer material) and a fixing unit that fixes the toner image formed on the sheet. The fixing unit includes a heating rotator that performs heating and a pressure rotator that is in pressure contact with the heating rotator. Among such image forming apparatuses, there is an image forming apparatus that weakens a pressure applied to a heating rotator by a pressure rotator when a paper jam (JAM) occurs (see Patent Document 1).

JP 2009-193020 A

  However, there is no conventional image forming apparatus that changes the pressure applied to the heating rotator by the pressure rotator according to the location where the paper is jammed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can easily remove a jammed material to be transferred when the material to be transferred is clogged.

  The present invention includes a conveyance path through which a transfer material is conveyed, an image forming unit that forms a toner image on the transfer material that has been conveyed through the conveyance path, a heating rotator that heats the transfer material, and the heating A pressure rotator for forming a fixing nip between the rotating body and pressurizing a transfer material carried into the fixing nip, and a nip pressure adjusting unit for adjusting a nip pressure of the fixing nip, A fixing unit disposed downstream of the image forming unit in the conveyance direction of the transfer material; a detection unit that detects clogging of the transfer material conveyed along the conveyance path; and The present invention relates to an image forming apparatus including a control unit that controls the nip pressure adjusting unit so as to change the pressure of the fixing nip in accordance with a clogging position of a transfer material when a clogging is detected.

  The image forming apparatus is disposed upstream of the image forming unit in the transfer direction of the transfer material, and adjusts the timing of supplying the transfer material to the image forming unit, and the fixing unit A transfer material discharge unit disposed further downstream in the conveyance direction of the transfer material, wherein the detection unit is disposed in the fixing unit and a first detection sensor disposed in the timing adjustment unit. It is preferable to include a second detection sensor that is provided and a third detection sensor that is disposed in the transfer material discharge portion.

  Further, the control unit detects the clogging of the transfer material in each of the first detection sensor and the second detection sensor, or in each of the second detection sensor and the third detection sensor, When detecting the clogging, it is preferable to control the nip pressure adjusting unit so that the pressure of the fixing nip is set to a second pressure smaller than the first pressure when the clogging of the transfer material is not detected.

  In addition, the controller controls the nip pressure adjusting unit so that the pressure of the fixing nip becomes a third pressure smaller than the second pressure when the clogging of the transfer material is detected only by the second detection sensor. It is preferable to control.

  The image forming apparatus includes a cooling unit that cools the fixing unit, and the control unit cools the fixing unit when the second detection sensor detects clogging of the transfer material. Is preferably controlled.

  In addition, the image forming apparatus includes a housing that houses therein the conveyance path, the image forming unit, the fixing unit, the detection unit, and the control unit, and the housing that can be opened and closed. And a lock unit for maintaining the cover unit in a closed state, and the control unit closes the cover unit while changing the pressure of the fixing nip. It is preferable to control the lock portion so as to maintain the state.

  According to the present invention, when the transfer material is clogged, the clogged transfer material can be easily removed.

1 is a diagram illustrating an overall configuration of a copier according to an embodiment of an image forming apparatus. 2 is a block diagram illustrating a functional configuration of a copier. FIG. FIG. 4 is a diagram for explaining details of a fixing unit. It is a figure for demonstrating the variation | change_quantity detection part.

  A copier according to an embodiment of an image forming apparatus of the present invention will be described below with reference to the drawings. First, the overall configuration of the copy machine 1 will be described. FIG. 1 is a diagram for explaining an overall configuration of a copier 1 according to an embodiment of an image forming apparatus.

The copier 1 includes a document transport unit 10, a document reading unit 20, a paper transport unit 30, an image forming unit 40, and a fixing unit 60.
The document transport unit 10 is an ADF (Auto Document Feeder), and includes a document placement unit 11, a first feed roller 12, a guide 13, a timing roller pair 14, and a document discharge unit 15. The first feed roller 12 supplies the document G placed on the document placement unit 11 to the timing roller pair 14 one by one in order. The timing roller pair 14 matches the timing at which the document reading unit 20 reads the document G with the timing at which the document G is supplied to the position at which the document G is read by the document reading unit 20 (the position at which the guide 13 is disposed). Then, the conveyance of the original G or the conveyance of the original G is stopped. The guide 13 guides the conveyed document G to a first reading surface 21a described later. The document discharge unit 15 discharges the document G read by the document reading unit 20 (passed through the guide 13) to the outside of the copier body 2.
A document stacking unit 16 is formed outside the copying machine main body 2 in the document discharge unit 15. In the document stacking unit 16, the documents G discharged from the document discharge unit 15 are stacked and stacked.

  The document reading unit 20 includes a first reading surface 21a and a second reading surface 22a. The first reading surface 21 a is formed along the upper surface of the first contact glass 21 disposed to face the guide 13 and serves as a surface for reading the document G. The second reading surface 22a is disposed adjacent to the first reading surface 21a (in the case shown in FIG. 1, over the most right side of the first reading surface 21a). The second reading surface 22 a is used when reading the document G without using the document transport unit 10. The second reading surface 22a is formed along the upper surface of the second contact glass 22 on which the document G is placed, and serves as a surface for reading the document G.

  The document reading unit 20 includes an illumination unit 23, a first mirror 24, a second mirror 25, a third mirror 26, an imaging lens 27, and an imaging unit 28 inside the copier body 2. . The illumination unit 23 and the first mirror 24 move in the sub-scanning direction X, respectively. The second mirror 25 and the third mirror 26 are disposed on the left side of the illumination unit 23 and the first mirror 24 in FIG. Further, the second mirror 25 and the third mirror 26 are the first reading surface 21 a or the second reading surface 22 a through the first mirror 24, the second mirror 25, the third mirror 26, and the imaging lens 27. To the imaging unit 28 while moving in the sub-scanning direction X while keeping the distance (optical path length) constant.

  The illumination unit 23 is a light source that irradiates the original G with light. The first mirror 24, the second mirror 25, and the third mirror 26 are mirrors for guiding the light reflected by the document G to the imaging lens 27 while keeping the optical path length constant. The imaging lens 27 focuses the light incident from the third mirror 26 on the imaging unit 28. The imaging unit 28 includes a plurality of imaging elements arranged along the main scanning direction (direction orthogonal to the sub-scanning direction X). The imaging element is an element for obtaining image data based on a formed optical image by converting incident light into an electrical signal, and is, for example, a charge coupled device (CCD).

  The paper transport unit 30 includes a transport path L, a second feed roller 31, a third feed roller 32, a timing adjustment unit 38, and a paper discharge unit (transfer material discharge unit) 34. The paper T is transported along the transport path L. The second feed roller 31 supplies the paper T (transfer material) stored in the paper feed cassette 36 to the transport path L. The third feed roller 32 supplies the paper T (transfer material) placed on the manual feed tray 37 to the transport path L. The timing adjustment unit 38 is arranged upstream of the image forming unit 40 in the sheet conveyance direction, and adjusts the timing of supplying the transfer material to the image forming unit 40. Specifically, the timing adjustment unit 38 includes a registration roller pair 33. The registration roller pair 33 conveys the sheet T or stops conveying the sheet T in order to match the timing at which a toner image is formed on the transfer unit 50 described later and the timing at which the sheet T is supplied to the transfer unit 50. The registration roller pair 33 (timing adjustment unit 38) corrects skew (oblique feeding) of the paper T. The paper discharge unit 34 is disposed downstream of the fixing unit 60 in the transport direction of the paper T, and discharges the paper T on which the toner image is fixed to the outside of the copier body 2. A paper discharge stacking unit 35 is formed outside the copier body 2 in the paper discharge unit 34. In the paper discharge stacking unit 35, the paper T discharged from the paper discharge unit 34 is stacked and stacked.

The image forming unit 40 includes a photosensitive drum 41, a charging unit 42, a laser scanner unit 43, a developing device 44, a cleaning unit 45, a toner cartridge 46, a primary transfer roller 47, and an intermediate transfer belt 48. The counter roller 49 and the transfer unit 50 are provided.
The photoconductor drum 41 (41a, 41b, 41c, 41d) functions as a photoconductor or an image carrier in order to form toner images of black, cyan, magenta, and yellow, respectively. Around each photosensitive drum 41a, 41b, 41c, 41d, in order from the upstream side to the downstream side along the rotation direction of the photosensitive drum 41, a charging unit 42, a laser scanner unit 43, a developing device 44, A cleaning unit 45 is disposed. The charging unit 42 charges the surface of the photosensitive drum 41. The laser scanner unit 43 is arranged away from the surface of the photosensitive drum 41 and scans and exposes the surface of the photosensitive drum 41 based on image data relating to the original G read by the original reading unit 20. As a result, the exposed portion of the charge is removed from the surface of the photosensitive drum 41 to form an electrostatic latent image. The developing device 44 forms a toner image by attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 41. The cleaning unit 45 removes toner and the like remaining on the surface of the photosensitive drum 41 after the surface of the photosensitive drum 41 is neutralized by a static eliminator (not shown).
The toner cartridge 46 stores toner of each color supplied to the developing device 44. The toner cartridge 46 and the developing device 44 are connected by a toner supply path (not shown).

  The primary transfer rollers 47 (47a, 47b, 47c, 47d) are arranged on the opposite sides of the intermediate transfer belt 48 from the photosensitive drums 41a, 41b, 41c, 41d, respectively. The intermediate transfer belt 48 is a belt that passes through the image forming unit 40 and the transfer unit 50. A part of the intermediate transfer belt 48 is sandwiched between the photosensitive drums 41a, 41b, 41c, and 41d and the primary transfer rollers 47a, 47b, 47c, and 47d, and the photosensitive drums 41a, 41b, 41c, and 41d. The toner image formed on the surface is primarily transferred. The counter roller 49 is a drive roller that is disposed inside the annular intermediate transfer belt 48 and advances the intermediate transfer belt 48 in the direction of arrow A shown in FIG.

  The transfer unit 50 includes a secondary transfer roller 51. The secondary transfer roller 51 is disposed on the opposite side of the intermediate transfer belt 48 from the counter roller 49, and a part of the intermediate transfer belt 48 is sandwiched between the counter roller 49. Further, the secondary transfer roller 51 secondarily transfers the toner image primarily transferred to the intermediate transfer belt 48 onto the paper T.

  The fixing unit 60 is disposed downstream of the image forming unit 40 in the transport direction of the paper T. The fixing unit 60 includes a heating rotator 61 and a pressure rotator 62. The heating rotator 61 heats the paper T. The pressure rotator 62 forms a fixing nip N with the heating rotator 61 and pressurizes the paper T carried into the fixing nip N. The paper T carried into the fixing nip N is heated by the heating rotator 61 and further pressurized by the pressure rotator 62, whereby the toner adhering to the surface is melted and pressed to fix the toner. . Details of the fixing unit 60 will be described later.

Next, the functional configuration of the copy machine 1 will be described. FIG. 2 is a block diagram showing a functional configuration of the copy machine 1.
The copier 1 includes the above-described components (the document transport unit 10, the document reading unit 20, the paper transport unit 30, the image forming unit 40, the transfer unit 50, and the fixing unit 60). Note that the description of the components described with reference to FIG. 1 is omitted. Furthermore, the copier 1 includes an operation unit 70, a storage unit 80, and a control unit 90 in addition to the above-described components.

  The operation unit 70 includes a numeric keypad (not shown), a touch panel (not shown), a start key (not shown), and the like. The numeric keypad is operated to input numbers such as the number of copies to be printed. The touch panel displays a plurality of keys to which various functions (for example, a function for setting a print magnification and a function for allocating a plurality of pages to one sheet of paper T (such as 2 in 1)) are assigned. The keys displayed on the touch panel are operated (touched) to cause the copier 1 to execute any of various functions. The start key is operated to execute printing. When any key is operated, the operation unit 70 supplies a signal indicating that this key has been operated to the control unit 90.

  The storage unit 80 includes a hard disk or a semiconductor memory. The storage unit 80 stores image data based on the document G read by the document reading unit 20. Further, the storage unit 80 stores a control program used in the copier 1, data used by the control program, and the like.

The control unit 90 controls the document conveying unit 10, the document reading unit 20, the operation unit 70, and the like.
An example of the function (operation) of the control unit 90 will be described by showing a case where the document G placed on the document placement unit 11 is copied. First, the control unit 90 detects that the start key has been operated by receiving a signal indicating that the start key constituting the operation unit 70 has been operated. Next, the control unit 90 drives the first feed roller 12 of the document transport unit 10 to supply the document G to the first reading surface 21a. The control unit 90 generates image data based on the document G supplied to the first reading surface 21 a by the document reading unit 20, and temporarily stores the image data in the storage unit 80. The control unit 90 forms a toner image on the paper T based on the image data temporarily stored in the storage unit 80, the paper transport unit 30, the image forming unit 40, the transfer unit 50, and the fixing unit 60. To control each. That is, the control unit 90 drives the second feed roller 31 or the third feed roller 32 to transport the paper T to the transfer unit 50. In addition, the control unit 90 supplies the color image data generated for each color based on the image data to the laser scanner unit 43, and the electrostatic latent image is applied to the photosensitive drum 41 by the laser light emitted from the laser scanner unit 43. Form an image. The control unit 90 causes the developing unit 44 to form a toner image on the photosensitive drum 41, and primarily transfers the toner image to the intermediate transfer belt 48. The controller 90 causes the secondary transfer roller 51 to secondarily transfer the toner image primarily transferred to the intermediate transfer belt 48 to the paper T. The control unit 90 controls the heating rotator 61 to be heated to a predetermined temperature so that the toner of the toner image secondarily transferred onto the paper T by the heating rotator 61 is melted, and the heating rotator 61 The toner is fixed to the paper T by the pressurizing rotating body 62 that is in pressure contact. Further, the control unit 90 causes the paper transport unit 30 to discharge the paper T on which the toner image is fixed from the paper discharge unit 34.

Next, details of the fixing unit 60 will be described. FIG. 3 is a diagram for explaining the details of the fixing unit 60. FIG. 4 is a diagram for explaining the fluctuation amount detection unit 653.
As shown in FIG. 3, the fixing unit 60 includes the heating rotator 61 and the pressure rotator 62 described above, a lever 63, a pressure mechanism 64, and a pressure adjustment mechanism 65 as a nip pressure adjustment unit. Is provided.

  The levers 63 are disposed at both ends of the pressure rotator 62. FIG. 3 shows only one of the two levers 63. The lever 63 supports the pressurizing rotator 62 to be rotatable in the vicinity of the center portion. Further, the lever 63 can be rotated with a fulcrum part 632 disposed on one end 631 side as a fulcrum, and when the other end 633 side is pushed down, the pressure rotator 62 is heated to the heating rotator 61. Move away from the direction. The pressurizing mechanism 64 urges the lever 63 to pressurize the heating rotator 61 by the pressurizing rotator 62. The pressurizing mechanism 64 is constituted by a compression spring, for example.

  The pressure adjustment mechanism 65 is disposed on the other end 633 side of the lever 63. The pressure adjustment mechanism 65 includes a cam 652 that is rotated by a motor 651 as a drive unit. The cam 652 rotates to resist the biasing force applied to the lever 63 by the pressurization mechanism 64, and the other of the lever 63. Push the end 633 down. As a result, the pressure rotator 62 moves away from the heating rotator 61 from the fixing state (see FIG. 3A) (see FIGS. 3B and 3C). Thereby, the nip pressure of the fixing nip N is adjusted.

  Further, the pressure adjusting mechanism 65 is provided with a fixing pressure fluctuation amount detecting unit 653 as shown in FIG. The fluctuation amount detection unit 653 includes a plurality of dimming units arranged on the rotation shaft of the cam 652. In the case shown in FIG. 4, three dimming portions (first dimming portion 654, second dimming portion 655, and third dimming portion 656) are provided in cam 652 (not shown in FIG. 4). The light transmission amounts of the respective dimming portions 654, 655, and 656 are different. The dimming units 654, 655, and 656 may be optical filters, for example. In addition, the fluctuation amount detection unit 653 includes a light emitting element 657 and a light receiving element 658 that receives light emitted from the light emitting element 657 and transmitted through any one dimming unit. In such a fluctuation amount detection unit 653, the axis on which the first dimming unit 654, the second dimming unit 655, and the third dimming unit 656 are rotated in the direction of arrow B as the cam 652 rotates. As a result, the dimming portion disposed between the light emitting element 657 and the light receiving element 658 changes, so that the amount of light received by the light receiving element 658 changes.

  For example, when the heating rotator 61 and the pressing rotator 62 are in contact with each other as shown in FIG. 3A, the light transmission amount between the light emitting element 657 and the light receiving element 658 is the largest. One dimming portion 654 is disposed. Thereby, the light receiving element 658 detects the first transmission amount of light. Based on the fact that the light receiving element 658 detects the first transmission amount, the control unit 90 determines that the pressure in the fixing nip N is the first pressure in order to perform fixing.

  When the heating rotator 61 and the pressure rotator 62 are in contact with each other as shown in FIG. 3B, the cam 652 rotates between the light emitting element 657 and the light receiving element 658. A second dimming unit 655 having a smaller light transmission amount than the first dimming unit 654 and a larger light transmission amount than the third dimming unit 656 is disposed. Thereby, the light receiving element 658 detects the second transmission amount of light. Based on the fact that the light receiving element 658 detects the second transmission amount, the control unit 90 determines that the pressure in the fixing nip N is a second pressure that is weaker than the first pressure.

  When the heating rotator 61 and the pressure rotator 62 are in contact with each other as shown in FIG. 3C, the cam 652 rotates between the light emitting element 657 and the light receiving element 658. A third dimming unit 656 having the smallest light transmission amount is disposed. Thereby, the light receiving element 658 detects the third transmission amount of light. Based on the fact that the light receiving element 658 detects the third transmission amount, the control unit 90 determines that the fixing nip N is at a third pressure that is weaker than the second pressure.

  The copier 1 including such a fixing unit 60 further includes a detection unit. The detection unit detects clogging of the paper T that is transported along the transport path L. The detection unit includes a first detection sensor 301 disposed in the timing adjustment unit 38, a second detection sensor 302 disposed in the fixing unit 60, and a third detection sensor 303 disposed in the paper discharge unit 34. . The first detection sensor 301, the second detection sensor 302, and the third detection sensor 303 are sensors that detect the paper T that is being transported along the transport path L. As a specific example, a contact-type arm sensor or a non-contact It is composed of a reflective sensor or the like. The contact-type arm sensor is a sensor that includes an arm that protrudes from the conveyance path L and detects the paper T when the paper T comes into contact with the arm. The non-contact reflection type sensor includes a light emitting element and a light receiving element that receives light emitted from the light emitting element and then reflected by the conveyance path L or the paper T. The non-contact reflection type sensor detects the paper T using a difference in intensity or the like between the light reflected by the conveyance path L and the light reflected by the paper T passing below the non-contact reflection type sensor. It is a sensor. Each of the detection sensors 301, 302, and 303 supplies a detection signal to the control unit 90 when the paper T is detected.

  When the detection unit (the first detection sensor 301, the second detection sensor 302, or the third detection sensor 303) detects the jamming of the paper T, the control unit 90 determines whether the fixing nip N is in accordance with the jammed position of the paper T. The pressure adjusting mechanism 65 is controlled to change the pressure. When the third detection sensor 303 does not detect the paper T within a predetermined time after the conveyance of the paper T from the registration roller pair 33 to the downstream side of the conveyance path L, the control unit 90 starts from the registration roller pair 33. It is determined that the paper T has been jammed at any point up to the paper discharge unit 34. In addition, when the detection signal is continuously supplied from at least one of the first detection sensor 301, the second detection sensor 302, and the third detection sensor 303, the control unit 90 continues to supply the detection signal. It is determined that the paper T is clogged at the place where is placed.

  Specifically, the control unit 90 detects the jam of the paper T in each of the first detection sensor 301 and the second detection sensor 302, or the paper T in each of the second detection sensor 302 and the third detection sensor 303. When detecting the clogging, the pressure adjusting mechanism 65 is controlled so that the pressure of the fixing nip N becomes a second pressure smaller than the first pressure when the clogging of the paper T is not detected.

  When the paper T is jammed from the fixing unit 60 to the registration roller pair 33, each of the first detection sensor 301 and the second detection sensor 302 detects the jam of the paper T. When the paper T is jammed from the paper discharge unit 34 to the fixing unit 60, each of the second detection sensor 302 and the third detection sensor 303 detects the jam of the paper T. In these cases, since the paper T is sandwiched between the heating rotator 61 and the pressure rotator 62 (pressed by the pressure rotator 62), it is difficult to take out from the fixing nip N. For this reason, the controller 90 rotates the cam 652 by driving the motor 651, and pushes down the other end 633 of the arm by the cam 652, so that the pressure rotator 62 is moved to the position shown in FIG. To the position shown in FIG.

  Specifically, the control unit 90 arranges the second dimming unit 655 between the light emitting element 657 and the light receiving element 658 so that the second light transmission amount is detected by the light receiving element 658 until the second transmission amount is detected. Rotate 652. If the rotation of the cam 652 is stopped when the second transmission amount is detected by the light receiving element 658, the pressure applied to the heating rotator 61 by the pressure rotator 62 (pressure of the fixing nip N) is the second pressure. It becomes. In this way, by changing the pressure in the fixing nip N to the second pressure that is smaller than the first pressure for fixing, the user can easily take out the paper T from the fixing nip N.

  The control unit 90 controls the pressure adjusting mechanism 65 so that the pressure in the fixing nip N becomes a third pressure smaller than the second pressure when only the second detection sensor 302 detects the jamming of the paper T. For example, when the sheet T becomes jammed in the fixing unit 60 and is jammed, only the second detection sensor 302 detects the jamming of the sheet T. In this case, the paper T is fed from the fixing nip N as compared with the case where the paper T is jammed from the fixing unit 60 to the registration roller pair 33 or the paper T is jammed from the paper discharging unit 34 to the fixing unit 60. Hard to take out. For this reason, the controller 90 rotates the cam 652 by driving the motor 651, and pushes down the other end 633 of the arm by the cam 652, so that the pressure rotator 62 is moved to the position shown in FIG. To move.

  Specifically, the control unit 90 arranges the third dimming unit 656 between the light emitting element 657 and the light receiving element 658, so that the cam 90 detects the third transmission amount by the light receiving element 658. Rotate 652. If the rotation of the cam 652 is stopped when the third transmission amount is detected by the light receiving element 658, the pressure applied to the heating rotator 61 by the pressure rotator 62 (pressure of the fixing nip N) is the third pressure. It becomes. Thus, by changing the pressure of the fixing nip N to the third pressure smaller than the second pressure, the user can easily take out the paper T from the fixing nip N.

  When the power of the copying machine 1 is turned on (when the power of the copying machine 1 is turned off while the pressure in the fixing nip N is being changed and then turned on), the first When any of the detection sensor 301, the second detection sensor 302, and the third detection sensor 303 detects the jam of the paper T, the control unit 90 changes the pressure of the fixing nip N (heats and rotates the pressure rotator 62). The pressure adjusting mechanism 65 may be controlled so as to move in a direction away from the body 61.

The copier 1 further includes a cooling unit 100 that cools the fixing unit 60. The cooling unit 100 may be an air cooling device such as a fan, for example.
In this case, the control unit 90 controls the cooling unit 100 to cool the fixing unit 60 when the second detection sensor 302 detects the jamming of the paper T. In other words, the control unit 90 detects that the paper T is jammed from the fixing unit 60 to the registration roller pair 33, the paper T is jammed from the paper discharge unit 34 to the fixing unit 60, or, for example, the fixing unit 60. When the paper T becomes clogged and clogs, the cooling unit 100 is controlled to cool the fixing unit 60. In particular, when the paper T is jammed in the fixing unit 60 and clogged, the user's finger may come into contact with the heating rotator 61 when clearing the paper jam. When the copier 1 detects the jam of the paper T by the second detection sensor 302, the cooling unit 100 cools the fixing unit 60, so that it is possible to avoid the risk of burns by the user.

  The copier 1 further includes a housing 3, a cover unit 3a, and a lock unit 3b. The housing 3 accommodates therein the image forming unit 40, the fixing unit 60, the detection unit (the first detection sensor 301, the second detection sensor 302, and the third detection sensor 303), the control unit 90, and the like. The cover portion 3a is disposed on the housing 3 so that it can be opened and closed. When the cover unit 3 a is opened, the user can remove the jammed paper T between the registration roller pair 33 and the paper discharge unit 34. The lock part 3b maintains that the cover part 3a will be in a closed state. That is, the lock part 3b locks the cover part 3a so that the cover part 3a is not opened. The lock part 3b may be configured using, for example, a solenoid. In this case, the lock unit 3b locks the cover unit 3a when the power is turned on under the control of the control unit 90, and the power of the copier 1 is turned off when the pressure in the fixing nip N is weakened. In this case, the cover portion 3a is configured to be unlocked.

While the pressure of the fixing nip N is being changed, the control unit 90 controls the lock unit 3b so that the cover unit 3a is maintained in the closed state. That is, when the pressure rotator 62 is moved away from the heating rotator 61 in order to change the pressure of the fixing nip N (when the motor 651 that rotates the cam 652 is driven), The control unit 90 locks the cover unit 3a with the lock unit 3b so that the cover unit 3a is not opened. Accordingly, when the cover portion 3a is opened while the pressure of the fixing nip N is changed, the change of the pressure of the fixing nip N is stopped in order to ensure the safety of the user (the pressure rotator 62). No need to stop movement).
Note that when the pressure of the fixing nip N is changed, the copying machine 1 may give a warning to the user by displaying on the touch panel that the pressure of the fixing nip N is changed. Good.

As described above, according to the copying machine 1 of the present embodiment, the following effects are produced.
That is, the copying machine 1 according to the present embodiment responds to the jamming position of the paper T when the detection unit (the first detection sensor 301, the second detection sensor 302, or the third detection sensor 303) detects the jamming of the paper T. Since the pressure adjusting mechanism 65 is controlled to change the pressure of the fixing nip N, the jammed paper T can be easily removed.

  Further, the copier 1 includes a first detection sensor 301 disposed in the timing adjustment unit 38, a second detection sensor 302 disposed in the fixing unit 60, and a third detection sensor 303 disposed in the paper discharge unit 34. Therefore, the pressure of the fixing nip N can be changed according to the position where the sensor that detects the jam of the paper T is disposed.

  Further, the copier 1 detects the jam of the paper T in each of the first detection sensor 301 and the second detection sensor 302, or the jam of the paper T in each of the second detection sensor 302 and the third detection sensor 303. When detecting, the pressure of the fixing nip N is changed to a second pressure smaller than the first pressure when the jam of the paper T is not detected, so that the pressure of the fixing nip N is changed according to the jam position of the paper T. Can be changed.

  Further, when the copier 1 detects the jam of the paper T only by the second detection sensor 302, the pressure of the fixing nip N is changed to a third pressure smaller than the second pressure, so that the paper T is brought into the jam position of the paper T. Accordingly, the pressure of the fixing nip N can be changed.

  In addition, since the copier 1 cools the fixing unit 60 by the cooling unit 100 when the second detection sensor 302 detects the jam of the paper T, the risk of burns by the user can be reduced. The jam of the paper T can be easily eliminated.

  Further, since the copying machine 1 keeps the cover portion 3a from being closed by the lock portion 3b when the pressure in the fixing nip N is changed, the pressure change in the fixing nip N stops midway. Can be prevented.

In addition, this invention is not limited to embodiment mentioned above, It can implement with a various form.
The copier 1 of the present embodiment is a color copier, but is not limited to this form and may be a monochrome copier.
In the copying machine 1 of the present embodiment, the toner image is transferred to the paper T via the intermediate transfer belt 48 (indirect transfer method). However, the present invention is not limited to this form, and is formed on the photosensitive drum. The transferred toner image may be directly transferred to the paper T (direct transfer method).
The copier 1 of the present embodiment is configured to print one side of the paper T, but is not limited to this, and may be configured to print both sides of the paper.

Further, the image forming apparatus of the present invention is not limited to the copying machine 1 described above. In other words, the image forming apparatus of the present invention may be a multi-function machine having a copy function, a facsimile function, a printer function, and a scanner function, or may be a facsimile or a printer.
The transfer material on which the toner image is fixed by the image forming apparatus of the present invention is not limited to the paper T, and may be a film sheet such as an OHP (overhead projector) sheet.

  DESCRIPTION OF SYMBOLS 1 ... Copy machine (image forming apparatus), 3 ... Housing | casing, 3a ... Cover part, 3b ... Lock part, 34 ... Paper discharge part (transfer material discharge part), 38 ... Timing adjustment part, 40 ... Image formation part, DESCRIPTION OF SYMBOLS 60 ... Fixing part, 61 ... Heating rotary body, 62 ... Pressure rotary body, 90 ... Control part, 100 ... Cooling part, 301 ... 1st detection sensor (detection part), 302 ... 2nd detection sensor (detection part), 303: third detection sensor (detection unit), L: transport path, N: fixing nip

Claims (6)

A transport path for transporting the transfer material;
An image forming unit that forms a toner image on a transfer material that has been transported along the transport path;
A heating rotator for heating the transfer material, a pressure rotator for forming a fixing nip between the heating rotator and pressurizing the transfer material carried into the fixing nip, and a nip of the fixing nip A nip pressure adjusting unit that adjusts the pressure, and a fixing unit disposed downstream of the image forming unit in the conveyance direction of the transfer material;
A detection unit for detecting clogging of a transfer material conveyed along the conveyance path;
A control unit that controls the nip pressure adjusting unit so as to change the pressure of the fixing nip according to the clogged position of the transfer material when the detection unit detects clogging of the transfer material;
An image forming apparatus comprising: A timing adjusting unit that is arranged upstream of the image forming unit in the conveyance direction of the transfer material and adjusts the timing of supplying the transfer material to the image forming unit;
A transfer material discharge unit disposed on the downstream side in the conveyance direction of the transfer material from the fixing unit; and
The detection unit includes a first detection sensor disposed in the timing adjustment unit, a second detection sensor disposed in the fixing unit, and a third detection sensor disposed in the transfer material discharge unit. Item 2. The image forming apparatus according to Item 1. The control unit detects clogging of the transfer material in each of the first detection sensor and the second detection sensor, or clogs the transfer material in each of the second detection sensor and the third detection sensor. 3. The image formation according to claim 2, wherein when detecting, the nip pressure adjusting unit is controlled so that the pressure of the fixing nip is a second pressure smaller than the first pressure when the clogging of the transfer material is not detected. apparatus. The control unit controls the nip pressure adjusting unit so that the pressure of the fixing nip becomes a third pressure smaller than the second pressure when the clogging of the transfer material is detected only by the second detection sensor. The image forming apparatus according to claim 3. A cooling unit for cooling the fixing unit;
5. The image forming apparatus according to claim 2, wherein the control unit controls the cooling unit to cool the fixing unit when the clogging of the transfer material is detected by the second detection sensor. 6. . A housing that accommodates the conveyance path, the image forming unit, the fixing unit, the detection unit, and the control unit;
A cover portion disposed in the housing to be openable and closable;
A lock part for maintaining that the cover part is in a closed state; and
The image according to any one of claims 1 to 5, wherein the control unit controls the lock unit to maintain the cover unit in a closed state while changing the pressure of the fixing nip. Forming equipment.

Images