JP2017203839A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can suppress damage to a surface of a contact target member and prevent the occurrence of paper jam.SOLUTION: An image forming apparatus comprises: a fixing part including a fixing member that is arranged on a fixing surface side of a recording medium on which a toner image is formed, and a pressure member that is arranged on a side opposite to the fixing surface, applies pressure to the fixing member to form a fixing nip, and fixes the toner image to the recording medium; a separation member that is in contact with at least one contact target member of the fixing member and pressure member to separate the recording medium ejected from the fixing nip from the contact target member; and an air blowing part that blows air to the separation member to move the separation member from a separation position to be separated from the contact target member to a contact position to come into contact with the contact target member.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus.

In general, an image forming apparatus (printer, copier, facsimile, etc.) using an electrophotographic process technology generates an electrostatic latent image by irradiating (exposing) a charged photoconductor with a laser beam based on image data. Form. Then, by supplying toner from the developing device to the photosensitive member (image carrier) on which the electrostatic latent image is formed, the electrostatic latent image is visualized to form a toner image. Further, after the toner image is directly or indirectly transferred to the paper, the image is formed on the paper by fixing by heating and pressing by the fixing unit.

  For example, the fixing unit includes a heating rotator disposed on the fixing surface side of the paper and a pressure rotator disposed on the surface opposite to the fixing surface of the paper. A pressure rotator is brought into pressure contact with the heating rotator to form a fixing nip for nipping and transporting the sheet.

  By the way, the toner of the toner image on the paper is heated when passing through the fixing nip, and therefore has adhesive force. As a result, the paper that has passed through the fixing nip is wound around the surface of the heating rotator and is not separated, which may cause jamming.

  Therefore, for example, in Patent Document 1, in order to separate the paper that is in close contact with the heating rotator (heat roller), the separation member (lever) is brought into contact with the heating rotator, and after separating the paper, An image forming apparatus that is separated from a heating rotator is disclosed.

  According to the image forming apparatus described in Patent Document 1, the heating rotator is compared with the image forming apparatus in which the tip of the separation member is always in contact with the heating rotator by separating the tip of the separating member from the heating rotator. It is possible to prevent the surface from being scratched, which causes image defects.

JP2015-138185A

  However, in the image forming apparatus described in Patent Document 1, when the urging force by the spring is applied to the separation member in a concentrated manner, the separation member repeatedly separates between contact and separation, for example, due to a difference in the individual springs. Since the member hits the heating rotator and the pressing force by the separating member is concentrated on the heating rotator, there is a risk of scratching the surface of the heating rotator. There is a problem in that a recording medium may enter a gap between the heating rotator and a paper jam may occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can prevent the surface of a contacted member from being damaged and prevent paper jams from occurring.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
A fixing member disposed on a fixing surface side on which a toner image of the recording medium is formed; and a fixing member disposed on an opposite surface side of the fixing surface to pressurize the fixing member to form a fixing nip. A fixing unit having a pressure member for fixing the toner image to
A separation member that separates the recording medium discharged from the fixing nip from the contacted member by contacting the contacted member of at least one of the fixing member and the pressure member;
An air blower for blowing air toward the separation member so as to move the separation member from a separation position separated from the contacted member to a contact position contacting the contacted member;
Is provided.

  According to the present invention, it is possible to prevent the surface of the abutted member from being damaged, and to prevent a paper jam from occurring.

1 is a diagram schematically showing an overall configuration of an image forming apparatus in the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus according to the present embodiment. FIG. 2 is a diagram schematically illustrating an enlarged part of a configuration arranged in a fixing device. FIG. 2 is a diagram schematically illustrating an enlarged part of a configuration arranged in a fixing device. It is a figure which shows roughly the flow of the air ventilated toward the separation member. It is a figure which shows schematically the separation member in the modification 1. FIG. It is a figure which shows a separation member roughly. It is a figure which shows schematically the separation member in the modification 2. It is a figure which shows schematically the separation member in the modification 2. It is a figure which shows schematically the separation member in the modification 2. It is a figure which shows schematically the separation member in the modification 2. It is a figure which shows schematically the separation member in the modification 3. It is a figure which shows roughly arrangement | positioning of the separation member in the modification 3. FIG. It is a figure which shows the control action of the ventilation part in the modification 4. It is a figure which shows schematically the ventilation part in the modification 5. FIG. It is a figure which shows the control action of the ventilation part in the modification 6. FIG. It is a figure which shows the control action of the ventilation part in the modification 6. FIG. It is a figure which shows roughly the intermittent ventilation part for isolation | separation in the modification 7. FIG. It is a figure which shows roughly the air suction part for isolation | separation in the modification 8. It is a figure which shows operation | movement of the air suction part for isolation | separation in the modification 8.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 shows a main part of the control system of the image forming apparatus 1 according to the present embodiment. An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421 (primary transfer). Then, after superposing four color toner images on the intermediate transfer belt 421, the toner images are transferred (secondary transfer) onto the sheet S as a recording medium, thereby forming an image.

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. Tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a sheet conveying unit 50, a fixing unit 60, a separating member 80, a blower unit 90, and A control unit 100 is provided.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms an image on the paper S based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.
The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on a document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like in accordance with a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and explanation, common constituent elements are denoted by the same reference numerals, and Y, M, C, or K are added to the reference numerals when distinguished from each other. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 has an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. It is a negatively charged organic photoconductor (OPC) in which a generation layer (CTL) and a charge transport layer (CTL) are sequentially stacked. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative polarity. The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 is, for example, a two-component developing type developing device, and forms a toner image by visualizing the electrostatic latent image by attaching toner of each color component to the surface of the photosensitive drum 413.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched around a plurality of support rollers 423 in a loop shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the belt running speed constant in the primary transfer portion. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 [log Ω · cm] on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 100. Note that the material, thickness, and hardness of the intermediate transfer belt 421 are not limited as long as they have conductivity and elasticity.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the backup roller 423B disposed on the downstream side in the belt traveling direction of the drive roller 423A. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. Specifically, a toner image is applied by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper S (the side in contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The sheet S to which the toner image is transferred is conveyed toward the fixing unit 60.

  The belt cleaning unit 426 includes a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer belt 421 and removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, or the like is stored for each preset type. . The conveyance path unit 53 includes a plurality of conveyance roller pairs such as registration roller pairs 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and a fixing process is performed in the fixing unit 60. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

  As shown in FIGS. 1 and 2, the fixing unit 60 includes an upper fixing unit 60 </ b> A having a fixing surface side member 62 disposed on the fixing surface (surface on which the toner image is formed) of the paper S, and the paper S. A lower fixing unit 60B having a back surface side support member 64 disposed on the back surface (the surface opposite to the fixing surface) side, a heating source 60C for heating the fixing surface side member 62, and the like are provided.

  For example, the upper fixing unit 60 </ b> A is a belt heating method, and includes an endless fixing belt 60 </ b> E as the fixing surface side member 62. The fixing belt 60E is stretched between a heating roller 60D including a heating source 60C and a fixing surface side member 62. Further, for example, the lower fixing unit 60 </ b> B is a roller pressing method, and includes a pressing roller as the back surface side support member 64. When the back surface side support member 64 is pressed against the fixing surface side member 62, a fixing nip for nipping and transporting the paper S is formed. The fixing belt 60E corresponds to the “fixing member” of the present invention. Further, the back side support member 64 corresponds to the “pressure member” of the present invention. The fixing belt 60E and the back side support member 64 correspond to the “contact member” of the present invention.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a unit.

  3 and 4 are diagrams schematically showing an enlarged part of the configuration arranged in the fixing device F. FIG.

  As shown in FIGS. 2 to 4, the fixing device F includes a separation member 80 for separating the paper S discharged from the fixing nip from the back surface side support member 64, and the separation member 80 as the back surface side support member 64. A blower 90 that blows air toward the separating member 80 is disposed so as to abut. In addition, the some separation member 80 is arrange | positioned along the longitudinal direction (axial direction of a pressure roller) of the back surface side support member 64 (refer FIG. 9). 3 and 4 show one of the plurality of separating members 80.

  The separating member 80 has a long shape. The separating member 80 is disposed on the back side of the paper S on the discharge side of the paper S in the fixing nip so that the longitudinal direction is orthogonal to the longitudinal direction of the back side support member 64.

  The separating member 80 has a distal end portion 82 on one end side in the longitudinal direction and a proximal end portion 84 on the other end side in the longitudinal direction. The distal end portion 82 of the separating member 80 has an edge extending along a direction (width direction) orthogonal to the longitudinal direction.

  A shaft portion of the shaft-shaped member 86 is fitted in an intermediate portion between the distal end portion 82 and the proximal end portion 84 in the separation member 80. The separation member 80 is supported so as to rotate around the shaft portion between a contact position where the separation member 80 is in contact with the back surface side support member 64 and a separated position where the separation member 80 is separated from the back surface side support member 64.

  The longitudinal direction of the back surface side support member 64, the width direction of the distal end portion 82 of the separation member 80, and the axial direction of the shaft portion of the shaft-shaped member 86 have a parallel relationship with each other. The entire edge of the front end portion 82 of the separation member 80 is obtained by pressing the front end portion 82 of the separation member 80 uniformly along the width direction by the blower 90 (described later). However, the back surface side support member 64 comes into contact. FIG. 3 shows the separation member 80 rotated to the separation position, and FIG. 4 shows the separation member 80 rotated to the contact position.

  The biasing member 88 is, for example, a tension spring, and is suspended between the base end portion 84 of the separation member 80 and the fixing portion (not shown) of the fixing device F, and moves the separation member 80 from the contact position to the separation position. Energize in the direction of rotation.

  The air blower 90 blows air toward the separation member 80 so as to rotate the separation member 80 to the contact position against the urging force of the urging member 88.

  As shown in FIGS. 2 to 4, the blower 90 includes a fan blower 92 and a blower duct 94.

  The fan blower 92 is a cylindrical multi-blade fan (so-called sirocco fan) in which a number of forward blades are erected on the circumference. The proximal end side of the air duct 94 is connected to the fan air blower 92. In the fan blower 92, air is sucked from the center of the fan and sent out in the centrifugal direction.

  The air duct 94 is disposed on the discharge side of the sheet S in the fixing nip and on the fixing surface side of the sheet S. An air discharge port 95 is provided at the tip of the air duct 94. The air duct 94 guides the air sent from the fan air blower 92 to the air discharge port 95.

  The air discharge port 95 blows air from the fixing surface side of the paper S toward the discharge side of the paper S in the fixing nip so that the paper S is separated from the fixing belt 60E. As shown by arrows in FIG. 4, the direction in which air is blown from the air discharge port 95 is changed to the direction of air blown from the air discharge port 95 by the fixing belt 60 </ b> E and directed to the separation member 80. Is set to

  FIG. 5 is a diagram schematically showing the flow of air blown toward the separating member 80. FIG. 7A schematically shows the separating member 80.

  As shown in FIGS. 5 and 7A, the distal end portion 82 of the separation member 80 has a width wider than the width of other portions (the base end portion 84 and the intermediate portion). Further, the air discharge port 95 has an opening width corresponding to the length in the width direction of the distal end portion 82 so that air is blown to the entire width direction of the distal end portion 82 of the separation member 80.

  The air blower 90 blows air toward the distal end portion 82 of the separation member 80 so as to rotate the separation member 80 to the contact position against the urging force of the urging member 88. As indicated by white arrows in FIG. 5, the air blowing unit 90 is arranged at the distal end portion 82 of the separating member 80 so as to press the distal end portion 82 of the separating member 80 uniformly along the width direction. Air is blown toward the entire width direction.

  The timing of blowing by the fan blowing unit 92 and the blowing rate [%] (the blowing rate ratio with respect to the maximum blowing rate) are controlled by the control unit 100.

  The control unit 100 controls the blowing timing so that the sheet S is blown toward the separation member 80 immediately before being discharged from the fixing nip. Here, the time immediately before the sheet S is discharged from the fixing nip means, for example, the time when the sheet S enters the fixing nip.

  When the control unit 100 receives a detection signal indicating that the last sheet S in the print job has passed through the sheet discharge unit 52 based on the movement of an actuator (not shown), the control unit 100 stops the blowing. To control.

  The control unit 100 adjusts the magnitude of the force that presses the separation member 80 by controlling the air flow rate. Specifically, the control unit 100 reduces the impact generated when the separation member 80 is brought into contact with the back surface side support member 64 and controls the air flow rate so as not to damage the surface of the back surface side support member 64. To do.

  According to the image forming apparatus 1 described above, the air is blown from the fixing surface side of the paper S toward the paper discharge side of the fixing nip immediately before the paper S is discharged from the fixing nip. The blown air hits the fixing belt 60E, the blowing direction is changed, and the air is directed toward the front end portion 82 of the separation member 80, and the air uniformly presses the front end portion 82 of the separation member 80 along the width direction, thereby The separation member 80 is rotated to the contact position against the urging force of 88, and the entire width direction of the front end portion 82 of the separation member 80 is brought into contact with the back surface side support member 64. Thereby, since the pressing force by the separating member 80 is not concentrated on the back surface side support member 64, it is possible to prevent the surface of the back surface side support member 64 from being damaged, and the sheet S is fixed to the fixing belt 60E and the fixing belt 60E. It can be separated from the back side support member 64.

  Further, according to the image forming apparatus 1 described above, the width of the distal end portion 82 of the separating member 80 is wider than the width of other portions such as the intermediate portion. Thereby, the area which receives air becomes wide and the pressing force which the front-end | tip part 82 receives with air becomes large. Further, in the separation member 80, the tip end portion 82 is located at a position away from the rotation center of the separation member 80 (the shaft portion of the shaft-like member 86). It becomes possible to enlarge.

(Modification 1)
Next, the separating member 80 according to Modification 1 will be described with reference to FIG.
FIG. 6 is a view schematically showing the separating member 80 in the first modification.
As shown in FIG. 6, play is provided between the separating member 80 and the shaft portion of the shaft-shaped member 86. Due to this play, the separating member 80 has a degree of freedom, can move on a surface orthogonal to the shaft portion, and can be tilted with respect to the shaft portion. In FIG. 6, the play is indicated by a gap S.

  Even when the separation member 80 has a degree of freedom, even when the parallel relationship (described above) between the width direction of the distal end portion 82 of the separation member 80 and the axial direction of the shaft portion of the shaft-like member 86 is not maintained. When the front end portion 82 of the separation member 80 is uniformly pressed along the width direction by the air blowing of the air blowing portion 90, the width direction of the front end portion 82 of the separation member 80 and the axial direction of the shaft portion of the shaft-shaped member 86 Return to a parallel relationship, and the entire width of the front end portion 82 of the separating member 80 contacts the fixing belt 60E. As a result, the front end portion 82 of the separating member 80 is prevented from coming into contact with the fixing belt 60E.

(Modification 2)
Next, a separation member 80 according to Modification 2 will be described with reference to FIGS. 7A to 7E.
FIG. 7A is a diagram schematically showing the separating member 80 according to the above embodiment. 7B to 7E are diagrams schematically showing a separating member 80 according to the second modification.

  As shown in FIG. 7A, the separation member 80 according to the above embodiment has a width of the distal end portion 82 as a region that receives the air blown by the blower portion 90, which is the other portion (base end portion 84 or intermediate portion). It is wider than the width.

  On the other hand, the separating member 80 according to the modified example 2 is obtained by widening the entire width along the longitudinal direction as shown in FIG. 7B, for example. That is, the entire area along the longitudinal direction is a region that receives air.

  Further, the separation member 80 shown in FIG. 7C is configured such that the width of the distal end portion 82 is wider than that of the separation member 80 of the above embodiment. That is, the area for receiving air becomes wider.

  Further, the separating member 80 shown in FIG. 7D is obtained by expanding the width of the distal end portion 82 and the width of the proximal end portion 84. The base end portion 84 is also a region that receives air. When the base end portion 84 is pressed by the air, the separation member 80 receives torque in a direction away from the back surface side support member 64. In the separation member 80 shown in FIG. 7D, by rotating the air blowing direction toward the distal end portion 82, the separation member 80 is rotated from the separated position to the contact position, and the air blowing direction is directed toward the proximal end portion 84. The air blowing unit 90 can be configured to rotate the separation member 80 from the contact position to the separation position.

  Further, the separating member 80 shown in FIG. 7E is obtained by expanding the width of the tip portion 82 and the width of the intermediate portion. Since the tip portion 82 and the intermediate portion are regions that receive air, the pressing force applied to the separation member 80 can be increased.

  In the second modification, various shapes of the region that receives air in the separation member 80 are shown. However, depending on the shape of the region that receives air, the shape and direction of the air discharge port 95 in the blower unit 90 are different. Is set.

(Modification 3)
Next, a separation member 80 according to Modification 3 will be described with reference to FIGS.
FIG. 8 is a view schematically showing the separating member 80 in the third modification. FIG. 9 is a diagram schematically showing a plurality of separation members 80 arranged along the axial direction of the back-side support member 64.

  In the second modification, in order to increase the area of the region that receives air in the separation member 80, a part or all of the width along the longitudinal direction is increased.

  On the other hand, in the third modification, the wind receiving plate 87 is provided on the separation member 80.

  The wind receiving plate 87 is provided on the separation member 80 with an inclination that easily receives air.

  As shown in FIG. 9, the plurality of separating members 80 are each provided with a wind receiving plate 87. Each wind receiving plate 87 is arranged so as not to leave a gap with the adjacent wind receiving plate 87 in order to receive the air blown from the blowing section 90 as much as possible. In addition, according to the shape of the area | region which receives the air in the separation member 80, the shape and ventilation direction of the air discharge port 95 in the ventilation part 90 are set.

(Modification 4)
Next, the control operation of the air blowing unit 90 according to Modification 4 will be described with reference to FIG. FIG. 10 is a diagram illustrating a control operation of the air blowing unit 90. In FIG. 10, the passage of time is represented on the horizontal axis, and the air flow rate is represented on the vertical axis. Here, a control operation before and after the first sheet S of the print job reaches the fixing nip when the print job is executed will be described. 10 is a period during which the sheet S passes through the fixing nip, and an interval between sheets is a period from when the sheet S passes through the fixing nip until the next sheet passes. Say.

  In the above-described embodiment, the blower 90 blows a predetermined blown amount at a time toward the separating member 80 immediately before the first sheet S is discharged from the fixing nip. In FIG. 10, the amount of air flow rising at once is indicated by a dotted line, and the amount of air flow increasing gradually is indicated by a solid line.

  In the above embodiment, as shown by a dotted line in FIG. 10, when the control unit 100 controls the air blowing unit 90 and increases the air blowing amount at a time, the separation member 80 moves rapidly. Thereby, the front end portion 82 of the separation member 80 gives an impact to the surface of the back surface side support member 64, but all of the front end portion 82 in the width direction comes into contact with the back surface side support member 64. It is possible to prevent an impact from being concentrated on one place. In addition, it is preferable to reduce the impact given to the surface of the back surface side support member 64 as much as possible.

  On the other hand, in the modified example 4, as shown by a solid line in FIG. 10, when the control unit 100 controls the air blowing unit 90 and gradually increases the air blowing amount, the separation member 80 moves gently. Thereby, the impact which the front-end | tip part 82 of the separation member 80 gives to the surface of the back surface side support member 64 can be made small, and it can further suppress that the surface of the back surface side support member 64 is damaged.

(Modification 5)
Next, the air blower 90 according to Modification 5 will be described with reference to FIG. FIG. 11 is a diagram schematically showing the air blowing unit 90.

  The air duct 94 in the air blowing section 90 according to the above embodiment changes the air blowing direction so that the paper S is separated from the fixing belt 60E and the separating member 80 is rotated to the contact position. Then, it is changed by the fixing belt 60E and directed to the separating member 80.

  By the way, when passing thick paper (for example, 180 gsm or more), since the paper is strong, separation from the fixing belt 60E is advantageous. On the other hand, a higher fixing temperature is required.

  In the embodiment described above, the fixing temperature due to air is lowered by directing the air blowing direction toward the fixing belt 60E. Therefore, it is necessary to maintain the fixing temperature at a high level by heating the fixing belt 60E so that the fixing temperature does not decrease when the thick paper is passed.

  On the other hand, the air duct 94 according to the modified example 5 has a first air blowing position in which the air blowing direction is directed to the fixing belt 60E when the thick paper is passed, and the air sending direction is a plain paper (for example, less than 180 gsm). It is comprised so that it may move between the 2nd ventilation positions toward the separation member 80 at the time of paper. In FIG. 11, the air blowing direction toward the fixing belt 60E is indicated by a broken line, and the second air blowing direction toward the separating member 80 is indicated by a solid line. In order to change the air blowing direction, a part of the air duct 94 (for example, the air discharge port 95) may be moved, or the whole air duct 94 may be moved.

  The control unit 100 controls the blower unit 90 to move the blower duct 94 to the second blower position when the thick paper is passed and to the first blower position when the plain paper is passed.

  In the above-described modification 5, it is possible to suppress a decrease in the fixing temperature due to air when the thick paper is passed, and thus it is possible to reduce the power consumption for heating the fixing belt 60E.

(Modification 6)
Next, the modification 6 will be described. The control operation of the blower 90 will be described with reference to FIG. FIG. 12 is a diagram illustrating a control operation of the air blowing unit 90. FIG. 12 shows the blown amount by a solid line.

  In Modification 5 described above, the control unit 100 moves the air duct 94 to the second air blowing position when the thick paper is passed to control the air blowing direction so that the air is not directed to the fixing belt 60E. . As a result, it is possible to suppress a decrease in the fixing temperature due to air when the thick paper is passed.

  On the other hand, in the modified example 6, by controlling the amount of air blown, the decrease in the fixing temperature due to air is suppressed when the thick paper is passed.

  Specifically, a paper sensor for detecting the paper S is provided at the entry position of the paper S in the fixing nip. For example, the control unit 100 refers to the linear velocity based on the detection signal of the paper sensor, and sets the time for the thick paper to reach the position approaching the separation member 80 at the timing when it contacts the fixing nip by about 5 mm from the leading edge of the paper S. Calculate as

  As shown in FIG. 12, the control unit 100 blows air at a predetermined blowing amount when the thick paper reaches the entry position of the fixing nip, causes the separation member 80 to contact the back side support member 64, and performs the above calculation. Based on the timing, the air blowing unit 90 is controlled so as to reduce the air blowing amount after the cardboard reaches the position approaching the separation member 80. Here, the “position approaching the separation member 80” includes the upper position of the separation member 80 when the thick paper passes over the separation member 80, and the separation member 80 when the thick paper passes under the separation member 80. , And a position in contact with the separation member 80.

  Although the timing when the air is blown is described as “when the thick paper reaches the entry position of the fixing nip”, it may be just before the paper S is discharged from the fixing nip. Further, as a mode of reducing the air blowing amount, the blowing amount may be lowered to 0%, or the blowing amount may be lowered to a predetermined amount that does not affect the fixing temperature.

  In the above-described modified example 6, the control unit 100 controls the amount of air blown at the time of passing thick paper. However, the control unit 100 also supplies air at the time of passing plain paper, as in the case of passing thick paper. The air volume may be controlled.

  Further, in the above-described modified example 6, the control unit 100 controls the air blowing unit 90 so that air is blown at a predetermined amount of air when the thick paper reaches the entry position of the fixing nip. For example, the control unit 100 may control the air blowing unit 90 so as to gradually increase the air blowing amount as shown by a solid line in FIG. As a result, it is possible to suppress a decrease in the fixing temperature due to air when the sheet S is passed, so that it is possible to reduce power consumption for heating the fixing belt 60E.

(Modification 7)
Next, the separation intermittent air blowing section 90A according to Modification 7 will be described. FIG. 14 is a diagram schematically showing the separation intermittent blower 90A.

  In the above-described modification example 6, when air is intermittently blown so as to adjust the blowing amount according to the passing of the paper S, the control unit 100 rotates the fan motor (not shown) of the blowing unit 90. By controlling the above, the amount of air blown is adjusted.

  On the other hand, in the modified example 7, in addition to the air blowing unit 90, an intermittent air blowing unit 90A for separation is provided. The separation intermittent blower 90A includes a nozzle 98, a compressor (not shown), an on-off valve (not shown), and the like. The control unit 100 controls the on-off valve so that the compressed air in the compressor is intermittently blown from the nozzle 98 toward the separation member 80. Thereby, the separation member 80 can be reliably rotated from the separated position to the contact position.

  For example, when passing thick paper, which is advantageous to be separated from the fixing belt 60E, the intermittent air blowing unit 90A for separation may be used alone without being used together with the air blowing unit 90.

(Modification 8)
Next, a separation air suction unit 90B according to Modification 8 will be described. FIG. 15A is a diagram schematically showing the separation air suction part 90B. FIG. 15B is a diagram showing the operation of the separation air suction unit 90B. 15A shows the separating member 80 lifted from the back side support member 64, FIG. 15B shows the separating member 80 in contact with the back side support member 64, and the air suction direction by the separation air suction part 90B is white. Indicated by an open arrow.

  In the above embodiment, the air blower 90 blows air to the separation member 80 by the paper S that is discharged from the fixing nip, separated from the fixing belt 60E by the separation member 80, and then passes above the separation member 80. Is blocked. As a result, the force with which the separation member 80 is pressed by air is reduced, the torque generated by the urging force of the urging member 88 is greater than the torque generated by the pressing force, and the separation member 80 moves from the contact position toward the separation position. To do. That is, the separation member 80 is lifted from the back side support member 64 (see FIG. 15A).

  On the other hand, in the modified example 8, the separation air suction part 90B is provided that rotates the separation member 80 to the contact position by sucking the air on the back surface side of the paper S. The control unit 100 sucks the separation air so that the air on the back side of the paper S is sucked when the paper S blocks air blowing to the separation member 80 (when the paper S passes above the separation member 80). The unit 90B is controlled. Thereby, even when the paper S blocks air blowing to the separation member 80, the separation member 80 can be prevented from floating from the back side support member 64 (see FIG. 15B).

  Note that an existing lower cooling fan for cooling the back surface side support member 64 may be used as the separation air suction portion 90B. The control unit 100 controls the separation air suction unit 90B to suck the air on the back side of the sheet S by rotating the lower cooling fan in the reverse direction.

  In the above embodiment, the separation member 80 is disposed on the back surface side support member 64 side (the back surface side of the sheet S), and the air blowing unit 90 is disposed on the fixing belt 60E side (the fixing surface side of the sheet S). However, the present invention is not limited thereto, and the separating member 80 may be disposed on the fixing belt 60E side, and the air blowing unit 90 may be disposed on the back surface side supporting member 64 side.

  In addition, each of the above-described embodiments is merely an example of a specific example for carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image forming part 50 Paper conveyance part 60 Fixing part 60A Upper fixing part 60B Lower fixing part 60C Heating source 60E Fixing belt 62 Fixing Surface side member 64 Back side support member 80 Separation member 90 Blower unit 90A Separation intermittent blower unit 90B Separation air suction unit 100 Control unit 101 CPU
102 ROM
103 RAM

Claims (11)

A fixing member disposed on a fixing surface side on which a toner image of the recording medium is formed; and a fixing member disposed on an opposite surface side of the fixing surface to pressurize the fixing member to form a fixing nip. A fixing unit having a pressure member for fixing the toner image to
A separation member that separates the recording medium discharged from the fixing nip from the contacted member by contacting the contacted member of at least one of the fixing member and the pressure member;
An air blower for blowing air toward the separation member so as to move the separation member from a separation position separated from the contacted member to a contact position contacting the contacted member;
An image forming apparatus. The separation member is biased in a direction to move from the contact position to the separation position;
The image forming apparatus according to claim 1, wherein the blower blows air toward the separation member such that the separation member is brought into contact with the contacted member against the biasing force.   The image forming apparatus according to claim 2, wherein the blower blows air from the fixing surface side toward a sheet discharge side of the fixing nip so as to separate the recording medium from the fixing member.   The image forming apparatus according to claim 2, wherein the rotation fulcrum of the separation member has a degree of freedom.   The image forming apparatus according to claim 1, wherein the separation member includes a wind receiving plate that receives the blown air.   The image forming apparatus according to claim 1, further comprising a control unit that controls the air blowing unit so that the recording medium is blown toward the separation member immediately before being discharged from the fixing nip. .   The image forming apparatus according to claim 6, wherein the control unit controls the blowing unit so as to gradually increase the blowing amount.   The image forming apparatus according to claim 7, wherein the control unit controls the air blowing unit so as to adjust the air blowing amount after the recording medium reaches a position approaching the separation member. The blowing section is configured to be able to change the direction of blowing,
The image forming apparatus according to claim 6, wherein the control unit controls the air blowing unit so as to change the blowing direction according to a type of the recording medium. An air suction part for sucking air from the surface opposite to the surface receiving the blown air in the separation member;
The controller controls the air suction unit to suck the air and keep the separation member at the contact position when the recording medium is transported to a position where the air blowing to the separation member is blocked. The image forming apparatus according to claim 6, wherein the image forming apparatus is controlled.   The image forming apparatus according to claim 1, wherein the fixing unit includes a belt as the fixing member and a roller as the pressure member.

Images