JP2019095533A - Fixation device - Google Patents

Abstract

To provide a fixation device having a structure of cooling a non-passage area of a recording material with cooling air, the fixation device capable of effectively cooling a non-passage area regarding a recording material of various width sizes.SOLUTION: A fixation device includes, at an end part of a shutter 56 configured to change an area of an air blow port 51 of a duct 52 guiding cooling air to a heating rotary body 33 on a side of the air blow port, a partition wall 61 projecting within the duct.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fixing device for fixing a toner image on a recording material. This fixing device can be used, for example, in an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine having a plurality of these functions.

  In the image forming apparatus as described above, after an unfixed toner image is formed on a sheet-like recording material (hereinafter referred to as a sheet) by the image forming means, the toner image is fixed as a fixed image by the fixing means.

  Although various methods have been proposed for the fixing means, a fixing device of a heat and pressure fixing method in which a toner image is fixed by heating and pressing is generally used. The fixing device includes a heating rotating body (fixing roller, fixing film, etc.) heated by the heating means, and a pressure rotating body (pressure roller, pressure belt, etc.) forming a fixing nip portion in pressure contact therewith. Have. Then, the two rotating members are rotated, and the sheet carrying the unfixed toner image is introduced into the fixing nip portion and nipped and conveyed, whereby the toner image is fixed on the sheet surface by the heat of the heating rotating member and the nip pressure. .

  In such a fixing device, when a small size sheet having a width smaller than the maximum size sheet having the maximum width that can be passed through the apparatus is continuously passed to perform fixing, the heating rotator is not In the sheet passing area (outside the recording material conveyance area), the surface temperature rises excessively. This is because when the small size sheet is continuously passed, in the non-sheet passing area where the sheet in the fixing nip portion does not pass, the heat is partially stored as much as there is no heat removal by the sheet. This phenomenon is referred to as temperature rise at the end of the fixing device or temperature rise at the non-sheet-passing portion, and when the temperature rise at the edge becomes high, it leads to the occurrence of hot offset and thermal deterioration of the components of the apparatus.

  A configuration has been proposed in which the non-sheet-passing area of the fixing device is cooled by the cooling air in order to suppress the temperature rise of the end portion during the continuous sheet-passing of the small size sheet. In Patent Document 1, the cooling air is selectively blown from the cooling fan disposed in the fixing device toward the non-sheet-passing area side. In Patent Document 2, when the cooling air is blown from the cooling fan to the non-sheet-passing area side, different width sizes are obtained by adjusting the length in the width direction of the air blowing port according to the width of the sheet to be used. Also in the case of the sheet, the non-sheet-passing portion temperature rise is prevented. In patent document 3, a partition wall is arrange | positioned in the duct for cooling, and it is suppressing that the flow volume of cooling air reduces in the shutter member vicinity which adjusts the length of the width direction of a ventilation opening.

JP-A-4-51179 JP 2003-076209 JP 2012-234067

  In the patent documents 1-3, it is corresponding to the paper of various width sizes to the cross direction by changing the area of the ventilation opening which guides cooling air. In this configuration, as the area of the air blowing port changes according to the various width sizes of the sheet, the shape of the air path of the cooling air inside the duct also changes. This may cause a loss of air volume in the duct or a change in wind direction after leaving the air outlet.

  (A) and (b) of FIG. 20 are schematic diagrams for describing the time of passing a small size sheet in the conventional fixing device.

  Reference numeral 131 denotes a fixing member (a heating rotator that heats an image on a sheet at a nip portion). 152 (L · R) are cooling ducts for left and right (longitudinal one end side and other end side of fixing member), 153 (L · R) are left and right cooling fans, and 156 (L · R) are left and right shutters. The duct 152 (L · R) guides the cooling air by the fan 153 (L · R) to the set area on the end side of the fixing member 131 in the width direction (longitudinal direction), and is a blower opening for cooling the area 151 (L · R). The shutter 156 (L · R) is moved by the shutter moving mechanism 154 so as to change the opening width of the air outlet 151 (L · R) according to the width of the sheet introduced into the apparatus.

  For example, when the shutter 156 (L · R) is at the position as shown in (a) with respect to the air outlet 151 (L · R) when passing a small size sheet, the cooling air is applied to the inner wall surface of the shutter. As shown by streamline Z, it is considered that vortices are generated in the vicinity of the inner wall surface of the shutter. In such a case, the flow rate in the vicinity of the shutter is lost, and the flow rate of the cooling air directed to the non-sheet-passing portion becomes uneven in the longitudinal direction.

  In the case where the partition wall 161 corresponding to the opening position of the shutter is disposed in the duct as shown in (b), the vortex D in the vicinity of the inner wall surface of the shutter is suppressed in the closed space and directed to the non-sheet passing portion The flow rate of the cooling air is made uniform in the longitudinal direction. However, if the positions of the shutter end and the partition wall shift, the flow rate in the vicinity of the inner wall surface of the shutter is lost by the same theory as in the case of (a) above, and the flow rate of the cooling air toward the non-sheet passing portion in the longitudinal direction It will be uneven.

  The present invention has been made in view of the above-described circumstances, and the objective of the present invention is a fixing device configured to cool a non-passing area of a recording material by a cooling air, for recording materials of various width sizes. Also in the non-passage zone is to cool efficiently.

  A representative configuration of a fixing device according to the present invention for achieving the above object is a heating rotating body for heating an image on a recording material at a nip portion, and setting of the width direction end of the heating rotating body A fan having a cooling fan for cooling the selected area, a duct having a blowing port for guiding the cooling air from the cooling fan to the heating rotor, and cooling the area, and the opening width of the blowing port being introduced into the apparatus A fixing mechanism having a shutter mechanism including a shutter that is moved to change according to the length of the recording material in the width direction, and projecting into the inside of the duct at an end of the shutter on the air blowing port side A partition wall for partitioning the inside of the duct so as to restrict the air path of the cooling air sent to the region through the air outlet by the cooling fan in the width direction. Do.

  According to the present invention, cooling air can be efficiently sent to the cooling area of the non-sheet-passing portion even for recording materials of various width sizes.

The figure that best describes the features of the invention Schematic configuration diagram of an image forming apparatus equipped with the fixing device according to the first embodiment FIG. 2 is an enlarged cross-sectional schematic view of a fixing device portion in the image forming apparatus of FIG. Front view of fixing device Longitudinal front view of fixing unit Block diagram of control system of fixing device External perspective view of the air blowing and cooling mechanism section seen from the side of the cooling fan External perspective view of the air blowing and cooling mechanism section seen from the side of the shutter mechanism External perspective view of the shutter mechanism External perspective view of the air blowing and cooling mechanism when the shutter is fully closed External appearance perspective view of the air blowing and cooling mechanism when the shutter is fully open Control flow chart of fixing device The longitudinal cross-sectional view of the ventilation cooling mechanism part of Example 2 The longitudinal cross-sectional view of the ventilation cooling mechanism part (the 1) of Example 3 The longitudinal cross-sectional view of the ventilation cooling mechanism part (the 2) of Example 3 Structural schematic diagram of the shutter mechanism part in Example 4 (the 1) Same as above (Part 2) Same as above (No. 3) Same as above (4) (A), (b) is a longitudinal sectional view for respectively explaining the time of small size sheet passing in the conventional fixing device

  DETAILED DESCRIPTION Exemplary embodiments of the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, etc. of the components described in this embodiment should be changed as appropriate depending on the configuration of the apparatus to which the invention is applied and various conditions, and The scope of the present invention is not intended to be limited to the following embodiments.

Example 1
(1) Image Forming Unit FIG. 2 is a schematic block diagram of an electrophotographic full color printer 100 as an example of an image forming apparatus equipped with the fixing device 20 according to the first embodiment. The printer 100 performs an image forming operation according to input image information from an external host device 300 such as a personal computer etc. communicably connected to the control circuit unit (control means: CPU) 200 to form a full color image on a recording material. Can be output.

  In the printer 100, the image forming unit 100A for forming a toner image on a recording material (hereinafter, paper) P forms a toner image of yellow (Y), magenta (M), cyan (C), and black (BK) 4 Image forming station 1 (Y, M, C, BK). Each image forming station 1 includes a drum-shaped electrophotographic photosensitive member (hereinafter abbreviated as drum) 2 which is rotationally driven in the clockwise direction of an arrow, and a charging roller 3 as a process device acting on the drum 2. The developing device 4, the primary charging roller 5, and the cleaning device 6 are provided.

  Further, the image forming unit 100A has a laser scanner 7 for scanning and exposing each drum 2 and a belt (intermediate transfer belt) 8 for carrying and conveying a toner image transferred from each drum 1 by the primary charging roller 5 . The image forming unit 100 </ b> A also includes a secondary transfer roller 12 that transfers a toner image from the belt 8 to the sheet P. The above-described electrophotographic process and operation of the image forming unit 100A are well known, so detailed description will be omitted.

  The sheets P are fed one by one from the feeding cassette 13 by the rotation of the feeding roller 14. The sheet P passes through a vertical conveyance path 15 having a pair of registration rollers 16 and is introduced to a secondary transfer portion 9 formed by the belt 8 and the secondary transfer roller 12, and secondary transfer of the toner image is performed from the belt 8 side. receive. Then, the sheet P is guided from the secondary transfer portion 9 to the vertical guide 19 and introduced into the fixing device 20, and the toner image of the sheet P is fixed as a fixed image. The sheet P which has exited the fixing device 20 passes through the conveyance path 21 and is sent out onto the sheet discharge tray 23 as an image forming object by the sheet discharge roller pair 22.

  When the duplex printing mode is selected, the sheet on which the first side has been printed is fed onto the sheet discharge tray 23 by the sheet discharge roller pair 22, and the trailing edge portion of the sheet just before the sheet passes the sheet discharge roller pair 22. At this point, the rotation of the discharge roller pair 22 is converted to reverse rotation. As a result, the sheet is switched back to be introduced into the re-conveying path 25, and the sheet is turned upside down and conveyed to the registration roller pair 16 again. Thereafter, as in the case of the first surface printing, the sheet is conveyed to the secondary transfer unit 9 and the fixing device 20, and is delivered onto the sheet discharge tray 23 as an image-formed material of double-sided printing.

(2) Fixing Device Next, the fixing device 20 of this embodiment will be described. In the following description, with respect to the fixing device or members constituting the same, the longitudinal direction (width direction) means the sheet conveyance road surface (the image forming surface of the sheet conveyed on the sheet conveyance path (image forming surface, printing In the plane parallel to the plane), it is a direction orthogonal to the sheet conveyance direction. With regard to the fixing device 20, the front is the sheet introduction side, and the left and right are the left or right when the fixing device is viewed from the front. The sheet width is the sheet size in the direction orthogonal to the sheet conveyance direction on the image forming surface of the sheet.

  FIG. 3 is an enlarged cross-sectional view of the fixing device 20 in the printer 100 of FIG. FIG. 4 is a schematic front view of the fixing device 20. The front side of the apparatus frame is cut away to look at the fixing mechanism. FIG. 5 is a schematic front view of the fixing mechanism section. FIG. 6 is a block diagram of a control system of the fixing device 20. As shown in FIG.

  The fixing device 20 is roughly divided into a film (belt) heating type fixing mechanism portion (fixing unit portion) 20A and a blowing and cooling mechanism portion (blowing and cooling unit portion) 20B.

(2-1) Fixing Mechanism Section The fixing mechanism section 20A basically has a belt (film) heating system / pressure rotary body driving system disclosed in JP-A-4-44075-44083, 4-204980-204984 etc. Is an on-demand fixing device.

  Reference numeral 31 denotes a film assembly (fixing unit), and reference numeral 32 denotes an elastic pressure roller (pressure rotating body: hereinafter, pressure roller) as a nip portion forming member. A fixing nip portion (hereinafter, a nip portion) N is formed by pressure contact of both the fixing film (heating rotating body) 33 of the film assembly 31 and the pressure roller 32. The sheet P is conveyed while being nipped by the nip portion N, and the image t formed on the sheet (on the recording material) is heated by the film assembly 31.

  In the film assembly 31, a cylindrical (endless belt-like, sleeve-like) 33 as a heating rotator is a flexible fixing film (hereinafter referred to as a film). Reference numeral 34 denotes a heat-resistant, rigid film guide (heater holding member and film guide member: hereinafter a guide member) having a substantially semicircular arc cross section. Reference numeral 35 denotes a ceramic heater (hereinafter referred to as a heater) as a heating source (heating body), which is fitted and fixed to the outer surface of the guide member 34 in a recessed groove provided along the longitudinal direction of the member. The film 33 is loosely fitted to the guide member 34 to which the heater 35 is attached.

  Reference numeral 36 denotes a pressure stay (hereinafter referred to as a stay) having a rigidity in a U-shape in cross section, which is disposed inside the guide member 34. The left and right end portions of the guide member 34 and the stay 36 project outward from the left and right openings of the film 33 in a predetermined manner (FIG. 5). An end holder 37 is fitted to the outward projecting arm portions 36a of the left and right ends of the pressing stay 36, and 37a is a flange integral with the left and right end holders 37.

  The film 33 is a composite layer structure in which an elastic layer, a release layer and the like are added to the outer peripheral surface of a heat resistant resin belt or metal belt as a base layer, and it is thin overall and has flexibility. Is a heat transfer member with high thermal conductivity and low heat capacity.

  The heater 35 is a low-heat-capacity, horizontally long, thin, planar heater extending in the longitudinal direction. The heater 35 basically includes a heater substrate of a ceramic material such as aluminum nitride alumina, and a conductive heat generating layer such as silver-palladium formed on the surface of the heater substrate. Since various types of ceramic heaters are known, the detailed description thereof is omitted.

  The pressure roller 32 is formed by providing an elastic layer 32 b of silicone rubber or the like on the outer periphery of the core metal 32 a and having a predetermined hardness. In order to improve the non-adhesiveness, a fluorine resin layer 32c such as PTFE, PFA, FEP or the like may be further provided on the outer periphery. The pressure roller 32 is a pressure member, and the left and right end portions of the core metal 32a are rotatably supported by bearings between the left and right side plates 38L and 38R of the apparatus frame 38 via the bearing members 41.

  The film assembly 31 is arranged parallel to the pressure roller 32 so that the heater 35 side is closely opposed, and the pressure spring 40 is disposed between the left and right end holders 37 and the left and right fixed spring receiving members 39. It is contracted. As a result, the stay 36, the guide member 34 and the heater 35 are pressed and urged toward the pressure roller 32. The film 33 and the pressure roller 32 are brought into pressure-contact with each other by pressing the surface of the heater 35 against the elasticity of the elastic layer 32b via the film 33 against the elasticity of the elastic layer 32b by the pressing force. A nip portion N having a predetermined width is formed in the sheet conveyance direction necessary for fixing.

  G is a drive gear (hereinafter referred to as a gear) fixed to the left end portion of the cored bar 32 a of the pressure roller 32. The rotational force of the motor M1, which is a device drive source, is transmitted to the gear G via a power transmission mechanism (not shown), whereby the pressure roller 32 is rotationally driven in the clockwise direction indicated by arrow R32 in FIG.

By the rotational drive of the pressure roller 32, a rotational force acts on the film 33 by the frictional force at the nip portion N between the pressure roller 32 and the outer surface of the film 33. As a result, the film 33 has its inner surface in close contact with the heater 35 at the nip N and slides in the counterclockwise direction of arrow R33 as the outer periphery of the guide member 34 is rotated with respect to the pressure roller 32 (additional Pressure roller drive system). Therefore, the film 33 rotates at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 32.

The flanges 37a of the left and right end holders 37 serve to receive the belt end on the side and restrict the movement when the rotating film 33 moves to the left or right along the longitudinal direction of the guide member 34. do. Grease (lubricant) is applied to the inner surface of the film 33, and the slidability of the film 33 with respect to the heater 35 and the guide member 34 is secured.

  The sheet P guided by the entrance guide 19 and introduced into the nip portion N is nipped and conveyed by the rotating pressure roller 32 and the film 33. In the present embodiment, the conveyance of the sheet P is performed by so-called central reference conveyance based on the center of the sheet width (the center of the recording material width). That is, the widthwise central portion of the sheet passes through the longitudinal central portion of the film 33 for sheets of any size, large or small, which can be passed through the apparatus. S is a reference line (virtual line) of the central reference conveyance.

  In FIG. 5, A is the effective heat generation area width of the heater 35. W1 is the sheet passing width (maximum sheet passing width) of the widest sheet which can pass through the apparatus. In the present embodiment, the maximum sheet passing width W1 is an A3 size width 297 mm (A3 longitudinal feed). The effective heat generation area width A of the heater 35 is set to be slightly larger than the maximum sheet passing width W1.

  W3 is the sheet passing width (minimum sheet passing width) of the minimum width sheet which can be passed through the apparatus. In the present embodiment, the minimum sheet passing width W3 is A5 longitudinal size width 148 mm (A5 longitudinal feed). W2 is a sheet passing width of the sheet between the widest sheet and the narrowest sheet. In the present embodiment, the sheet passing width W2 indicates the B4 size width 257 mm (B4 longitudinal feed). Hereinafter, a sheet having a width corresponding to the maximum sheet passing width W1 is referred to as a maximum size sheet, and a sheet having a width smaller than the sheet is referred to as a small size sheet.

  a is a difference width portion between the maximum sheet passing width W1 and the sheet passing width W2 ((W1−W2) / 2), and b is a difference width portion between the maximum sheet passing width W1 and the minimum sheet passing width W3 ((W1−W3) / 2) It is. That is, the non-sheet-passing portions a and b are non-sheet-passing portions generated when the small-size sheets B4 and A5 are passed.

  As described above, the non-sheet-passing portions a and b are a partial region of the film 33, and a sheet narrower in width than the maximum size sheet that can be conveyed by the nip portion N is conveyed in the longitudinal direction. It is a non-passing area of the sheet (outside the passing area (conveying area) of the recording material).

  In the present embodiment, since the conveyance of the sheet is the center reference, the non-sheet passing portions a and b are generated on both the left and right side portions of the sheet passing width W2 and the left and right side portions of the minimum sheet passing width W3. The width of the non-sheet passing portion varies depending on the size of the width of the small size sheet to be used.

  TH1 and TH2 are two main and sub thermistors as first and second temperature detection means (temperature detection element: detection means for detecting temperature). The main thermistor TH1 is disposed so as to elastically contact the inner surface of the film 33 so as to detect the temperature of the film portion where a sheet of any size, large or small, will be the sheet passing portion. Specifically, the main thermistor TH1 is supported by the free end of a leaf spring-shaped elastic support member 44 whose base is fixed to the guide member 34. The main thermistor TH1 is disposed so as to elastically contact the inner surface of the film 33 by the elasticity of the elastic support member 44.

  The sub-thermistor TH2 makes contact with the back of the heater so as to detect the temperature of the heater portion which becomes the non-sheet passing portion when a sheet of a width smaller than the sheet of the maximum width which can pass through the apparatus is passed. It is arranged to do.

  The main thermistor TH1 may be arranged to detect the heater temperature corresponding to the minimum sheet passing width W3. Conversely, the sub-thermistor TH2 may be disposed so as to elastically contact the inner surface of the base layer of the film portion corresponding to the non-sheet-passing portion a.

  The heater 35 is energized from a heater drive circuit 92 (FIG. 6) as a power supply unit through a feed line and a connector (both not shown) to the heat generating layer provided on the surface of the heater substrate. . As a result, the heater rapidly rises in temperature over the effective heat generation area width A. The temperature of the film 33 is detected by the main thermistor TH 1, and electrical information on the film temperature is input to the control circuit unit 200 via the A / D converter 81. Further, electrical information related to the heater temperature detected by the sub-thermistor TH2 is input to the control circuit unit 200 via the A / D converter 82.

  The control circuit unit 200 determines the temperature adjustment control content of the heater 35 based on the outputs of the main thermistor TH1 and the sub thermistor TH2, and controls the energization of the heater 35 from the heater drive circuit 92.

  The control circuit unit 200 controls the motor drive circuit 91 to drive the motor M1 based on a print signal from the external host device 300 or another control signal. Thus, the pressure roller 32 is rotationally driven, and the film 33 is also rotated. Further, the heater drive circuit 92 is controlled to start the heat-up of the heater 35.

  When the rotational speed of the film 33 is steady and the temperature of the heater 35 rises to a predetermined level, the sheet P carrying the unfixed toner image t from the image forming unit 100A side to the nip N is guided along the entrance guide 19 Introduced. The toner image bearing surface side of the sheet P faces (faces) the film 33.

  The sheet P is conveyed while being nipped by the film assembly 31 and the pressure roller 32 at the nip portion N. In the transport process, heat is applied to the sheet P by the film 33 heated by the heater 35, and the toner image t is fixed by heat and pressure on the surface of the sheet P by the nip pressure. The sheet P nipped and conveyed at the nip portion N is separated from the surface of the film 33 and discharged and conveyed.

(2-2) Blowing Cooling Mechanism The blowing cooling mechanism 20B is a non-passing of the fixing mechanism 20A which occurs when continuously passing a small-size sheet having a width smaller than the sheet of the maximum width which can be passed through the apparatus. It is a blast cooling means for cooling the temperature rise in the paper area by blast.

  FIG. 7 is an external perspective view of the air blowing and cooling mechanism portion 20B, viewed from the side of the cooling fan, and the film assembly 31 on the fixing mechanism portion 20A side is also written. FIG. 8 is also an external perspective view of the air blowing and cooling mechanism portion 20B, viewed from the side of the shutter mechanism, and the film assembly 31 on the fixing mechanism portion 20A side is also written. FIG. 9 is a perspective view showing the appearance of the shutter mechanism. FIG. 10 is a view showing a state in which the shutter as the opening width changing member is moved to the fully closed position in which the air blowing port is fully closed. FIG. 11 is a state diagram in which the shutter has moved to the fully open position in which the air blowing port is fully opened.

  The blower cooling mechanism unit 20B has a cooling fan 53 (L · R) for cooling the set region on the width direction end side of the film 33. In addition, the air blowing and cooling mechanism unit 20B has ducts 52 (L and R) including air blowing ports 51 (L and R) for guiding the cooling air by the cooling fan to the film 33 and cooling the region. In addition, the air blowing and cooling mechanism unit 20B includes a shutter mechanism 54 including a shutter 56 (L and R) which is moved so as to change the opening width of the air blowing port according to the width direction length of the sheet P introduced into the apparatus. Have.

  In the present embodiment, as shown in FIG. 3, a film 33 is provided with a cooling fan 53 (L · R) as a blower and a cooling duct 52 (L · R) for guiding the wind from the cooling fan to the non-sheet passing area. It is located downstream of the side. A horizontal partition 50 substantially parallel to the blowing direction is disposed inside the cooling duct 52 (L, R). As a result, the cooling air is directed to the downstream side in the sheet conveyance direction.

  In the following description, in order to indicate the left and right with respect to the cooling fan 53 etc., subscripts L and R may be added to the reference, and the subscript L and R are used when there is no need to distinguish between the left and right. I omit it.

  The pair of left and right cooling ducts (hereinafter referred to as ducts) 52 (L and R) are disposed so as to project from the cooling fans (hereinafter referred to as fans) 53 (L and R) toward the fixing mechanism portion 20A. The duct 52 (L · R) is provided with an opening where the fan 53 (L · R) is disposed, and the tip end opposite to the fan mounting portion is opened as an air outlet (air outlet) ing. The tip end side is the air flow path (air path, flow path) downstream side by the fan 53 (L and R) and the fixing mechanism portion 20A side.

  The shape of the duct 52 (L · R) is the same shape or symmetrical with respect to the reference line S of the central reference conveyance in FIG. 5 (the longitudinal center of the film 33), and the air flow path of the duct 52 (L · R) is The film 33 is disposed in a direction substantially perpendicular to the generatrix (film width direction) of the film 33.

  When the fan 53 (L · R) is turned on, air is drawn from the air suction duct (not shown) in the apparatus main body, and the cooling air is blown into the duct 52 (L · R), and from each air outlet Air blows out. In the present embodiment, an axial fan is used as the fan 53 (L · R).

  A shutter mechanism (shutter unit) 54 as opening width adjusting means is provided on the tip end side (fixing mechanism portion 20A side) of the duct 52 (L, R) of the air blowing and cooling mechanism portion 20B. The outer surface side (the fixing mechanism portion 20A side) of the shutter mechanism 54 and the film assembly 31 of the fixing mechanism portion 20A are disposed to face each other so as to be close to each other.

  The shutter mechanism 54 has a shutter frame 55 whose longitudinal direction is the left and right direction. At the left and right portions of the shutter frame 55, air outlets 51 (L, R) are respectively provided, and the ducts 52 (L, L) correspond to (substantially match) the air outlets 51 (L, R).・ R air outlet is provided. Here, the air outlets 51 (L, R) of the shutter frame 55 and the air outlets of the duct 52 (L, R) constitute air outlets of the duct 52 (L, R). The air vents 51 (L and R) of the duct 52 (L and R) are disposed to face the non-sheet-passing area of the film 33.

  Further, on the shutter frame 55, a shutter (shutter plate) 56L capable of changing the opening width of the air outlet 51L on the left side, and a shutter 56R adjusting the opening width of the air outlet 51R on the right side are disposed. The left and right shutters 56 (L and R) are held by the shutter frame 55 so as to be slidable in the left and right direction along the air outlets 51 (L and R), as indicated by arrows in FIG.

  In addition, left and right racks 57 (L and R) and pinion gears 58 are provided to move the left and right shutters 56 (L and R) in conjunction with each other in the left and right direction. The left rack 57L is integrally formed with the left shutter 56L, and the right rack 57R is integrally formed with the right shutter 56R. The pinion gear 58 meshes with both left and right racks 57 (L and R).

  Further, as shown in FIG. 9, a partition 61 substantially perpendicular to the moving direction of the shutter 56 (L · R) is disposed at the opening end of the shutter 56 (L · R). Here, the partition 61 corresponds to a partition wall that partitions the space inside the duct so that the wind path of the wind from the fans 53 (L and R) does not escape in the longitudinal direction.

  Here, the partition 61 on the L side is configured integrally with the shutter 56L, and the partition 61 also moves in the left-right direction as the shutter 56L moves. The R-side partition 61 is configured integrally with the shutter 56R, and the R-side partition 61 also moves in the left-right direction as the shutter 56R moves. In the longitudinal direction of the film 33, the partition 61 is connected on the outer side (closer to the end of the film 33) of the shutter 56 (L · R).

  The pinion gear 58 is driven to rotate in the forward or reverse direction by a shutter motor (pulse motor) M2 disposed in the main body frame (not shown). As the pinion gear 58 is driven to rotate forward or reverse by the shutter motor M2, the left and right shutters 56 (L and R) interlock with each other and reciprocate with the same amount of movement in the approaching or separating direction. That is, it opens and closes with respect to the blower vent 51 (L · R). As a result, the opening widths of the left and right air outlets 51 (L and R) of the shutter mechanism 54 in the left-right direction are adjusted in synchronization so as to be equal.

  When the width information of the sheet to be fed is a large size sheet of A3 size width, the control circuit unit 200 controls the shutter motor drive circuit 93 to make the shutter 56 (L · R) as shown in FIG. To move. That is, the shutter 56 (L · R) is moved to the fully closed position where the air outlet of the duct 52 (L · R), ie, the air outlet 51 (L · R) is fully closed.

  In the case of a small size sheet of A5R size width, as shown in FIG. 11, the shutter 56 (L · R) is an air outlet of the duct 52 (L · R), ie, the air outlet 51 (L · R). Move to the fully open position.

  When the recording material is a small size recording material of B4 size width, the shutter 56 (L · R) is an air outlet of the duct 52 (L · R) at a portion corresponding to the non-sheet passing portion a (FIG. 5), That is, it moves to a position where the air outlet 51 (L · R) is opened.

  Here, when the small-size sheet to be passed is LTR-R, EXE, LTR, etc., the control circuit unit 200 is configured so as to correspond to the non-sheet passing portion generated in those cases. The shutter 56 (L · R) is moved to the position where L · R) is opened. That is, the shutters 56 (L and R) are provided adjustably in accordance with the width (longitudinal length) of the sheet passing through the opening width (air blowing width) of the air blowing port (air blowing port) . The minimum, maximum, and total sheet sizes (various sizes) in the present embodiment refer to fixed form paper guaranteed by the image forming apparatus main body, and does not mean irregular sized paper that is used uniquely by the user.

  As shown in FIG. 9, the position information of the shutter 56 (L · R) is a flag 59 arranged at a predetermined position of the shutter 56 (L · R) by a sensor 60 arranged on the main body frame (not shown) To detect. Specifically, the home position is determined at the shutter position where the air outlet (air outlet) is fully closed, and the opening amount is detected from the rotation amount of the shutter motor M2.

  In addition, an aperture width detection sensor is provided which directly detects the current position of the shutter 56 (L · R). Then, shutter position information by the sensor is fed back to the control circuit unit 200, and the shutter 56 (L · R) is controlled to move to an appropriate opening width position corresponding to the width of the sheet to be passed. It is also good.

  The stop position of the shutter 56 (L · R) can accurately determine the position corresponding to the length in the width direction of the small size sheet by detecting the edge position of the shutter 56 (L · R) with a sensor. Therefore, the cooling air can be blown to the non-sheet passing area of all the small size sheets.

  Next, the operation of the left and right fans 53 (L and R) in the fixing device 20 of this embodiment will be described with reference to the flowchart of FIG. The operation control of the cold fan 53 (L · R) is performed by the control circuit unit 200 controlling the cooling fan drive circuit 94.

  When the print start signal is received (step S1), energization of the heater 35 is started (step S2), and the temperature rising operation of the fixing device 20 is started. When the fixing device 20 reaches a predetermined temperature, temperature control and print operation are started so that the temperature of the main thermistor TH1 becomes a predetermined fixing temperature (step S3).

  Thereafter, when the printing is not continued (N in step S4), the printing is ended (step S11). On the other hand, if printing is to be continued (Y in step S4), the shutter 56 (L · R) is detected when the detection temperature Tsub of the sub thermistor TH2 becomes equal to or higher than the cooling fan driving temperature Tfan-on during printing (Y in step S5). ) Based on the sheet width (step S6). Thereafter, drive of the fan 53 (L · R) (cooling operation by the fan) is started (step S7). That is, the control circuit unit (execution means) 200 executes the cooling operation by the fan when the temperature detected by the sub thermistor TH2 rises to the set temperature.

  When printing is further continued (Y in step S8), the non-sheet-passing area is cooled by the fan 53 (L · R). Thereafter, when the detected temperature Tsub of the sub thermistor TH2 becomes equal to or lower than the cooling fan driving temperature Tfan-off (Y in step S9), the driving of the fan 53 (L · R) is stopped (step S10), and the process returns to step S4. If printing is not continued in step S8, printing is ended (step 11).

  FIG. 1 is a schematic cross-sectional view of the air blowing and cooling mechanism unit 20B when small size paper is passed. In the present embodiment, the shutter 56 (L · R) is provided at the end of the opening portion (blow side) of the shutter 56 (L · R) so as to divide the inside of the left and right ducts 52 (L · R). A partition (partition wall) 61 is disposed in a direction (generally perpendicular direction) perpendicular to the moving direction of the frame. Thus, the inside of the duct 52 (L · R) is divided by the partition 61, and the shutter 56 (L · R) and the closed space D shielded by the partition 61 and the shutter 56 (L · R) are opened. Two regions of open space E are formed.

  Here, since the cooling air flowing in the closed space D and the open space E is blocked by the partition 61, they do not affect each other. In the closed space D, the cooling air blocked by the shutters 56 (L and R) and the partitions 61 forms a vortex and consumes all of the flow rate. Further, in the open space E, the cooling air from the fan 53 (L · R) flows along the partition 61 in parallel with almost no flow loss, and the opening width of the shutter 56 (L · R) with respect to the film assembly 31 Cooling a longitudinal region of approximately the same width as at a uniform flow rate.

  On the other hand, in the conventional configuration without the partition 61 as shown in (a) of FIG. 20 described above, the vortex Z formed in the area shielded by the shutter 156 (L · R) is the shutter 156 (L · R) Affect the cooling air in the open area. For example, the flow rate of the cooling air in the opening area of the shutter 156 (L · R) in the area close to the vortex Z may increase or decrease. As a result, the fixing member (film assembly) 131 is cooled at a non-uniform flow rate in the longitudinal direction.

  Further, in the conventional configuration in which the partition 161 is provided on the side of the duct 152 (L · R) as shown in FIG. 20 (b) described above, the longitudinal position of the partition 161 and the longitudinal position of the tip position of the shutter 156 (L · R) When a positional deviation occurs in the direction, the mechanism is the same as (a) in FIG. That is, the cooling air in the area where the shutter 156 (L · R) is open is affected in the area close to the vortex, and the flow rate of the cooling air becomes uneven in the longitudinal direction.

  As described above, in the present embodiment, the shutter 56 (L for blocking the cooling air blown by the fans 53 (L and R) in the blower / cooling mechanism 20B for cooling the non-sheet-passing portion of the fixing mechanism 20A. The partition 61 is disposed at the open end (the end on the air outlet side) of R). The partition 61 protrudes inside the duct 152 (L · R), and the space inside (internal) of the duct 52 (L · R) is perpendicular to the moving direction of the shutter 56 (L · R) (substantially perpendicular direction Divided into By this partition 61, the flow rate of the cooling air from the fan 53 (L · R) toward the non-sheet-passing portion of the film assembly 31 can be made uniform in the longitudinal direction.

  Therefore, it is possible to eliminate temperature unevenness in the sheet passing area and excessive temperature increase in the sheet non-passing area, and it is possible to prevent fixing defects such as conveyance speed reduction on small size paper and unevenness in gloss of the image. .

Example 2
The second embodiment will be described below. In the first embodiment, when the partition 61 is disposed substantially perpendicular to the moving direction of the shutter 56, that is, the wind sent along the partition 61 is directed to the opening of the shutter 56 in the vertical direction. The case where it arranges was explained.

  As shown in FIG. 13, the partition 61 is configured such that the direction of the wind sent along the partition 61 is directed from the opening on the film 33 side so that the direction of the wind away from the sheet passing area is in one direction with respect to the longitudinal direction. The opening may be arranged to expand toward R). Here, the sheet passing area is a partial area of the film 33 and is a passing area of the sheet when the sheet is conveyed.

  In other words, the cooling air flow may be inclined from the fan 53 (L · R) toward the duct opening so that the cross-sectional area of the cooling air decreases. That is, the partition 61 protrudes from the film 33 side in the direction of the fan 53, and may be disposed in a direction in which the opening is expanded from the film 33 toward the fan 53. As a result, the flow rate of the cooling air from the fan 53 (L · R) at an arbitrary opening width increases as compared to the case where the partition 61 does not have an inclination, and the cooling efficiency can be further improved.

Example 3
The third embodiment will be described below. As shown in FIG. 14, a plurality of fans 53 (L and R) can be arranged side by side in the longitudinal direction, for example, two on the left (53L1, 53L2) and two on the right (53R1, 53R2), Indicates Thereby, the longitudinal width which can be cooled can be enlarged.

  On the other hand, the fans 53 (L and R) can selectively control individual operations, and by stopping the rotation of part of the plurality of fans 53, the amount of electricity consumption can be reduced. As an example, as shown in FIG. 15, when the positions of the partitions 61 coincide with the longitudinal end X of the fans 53L2 and 53R2 or the opening width is narrower than that, all the cooling air of the fans 53L2 and 53R2 is a shutter It is shielded by 56 (LR) and the partition 61. That is, the flow rate is consumed in the closed space D.

  In this case, since the cooling efficiency does not change depending on the presence or absence of the operation of the fans 53L2 and 53R2, the amount of electricity consumption can be suppressed by stopping the operation of the fans 53L2 and 53R2.

  As described above, since the partitions 61 are provided, by selectively stopping the fans in the configuration in which the plurality of fans are arranged in the longitudinal direction, it is possible to suppress the amount of electricity consumption without reducing the cooling efficiency.

  In the third embodiment, as in the second embodiment, the partitions 61 are arranged with an inclination such that the opening is expanded from the opening on the film assembly 31 side toward the fan 53 (L · R) in the longitudinal direction. For example. However, the present invention is not limited to this, and the partition 61 may be disposed substantially perpendicular to the shutter movement direction as in the first embodiment.

Example 4
(1) In the fixing device 20 according to the first to third embodiments, the conveyance of the sheet is the center reference conveyance of the sheet width center. Then, two air outlets 51 (L, R) are installed symmetrically with respect to the reference line S of the central reference conveyance, and one shutter 56 (L, R) for each air outlet. The shutter mechanism 54 having the above-described configuration is disposed (one-side shutter configuration).

  Not limited to this, the conveyance of the sheet may be performed by one-side reference conveyance. That is, as shown in the schematic view of FIG. 16, the fixing device 20 is one-side reference conveyance based on one end side of the sheet, and the number of the air vents 51 is one. The shutter mechanism 54 having the shutter 56 may be disposed.

  (A) shows a state where the shutter 56 is moved to a position where the air outlet 51 is fully closed, (b) shows a state where the shutter 56 is moved to a position where the air outlet 51 is fully open . SA indicates a reference line (virtual line) of one-side reference conveyance, arrow 56a indicates the closing movement direction of the shutter 56, and arrow 56b indicates the opening movement direction.

  (2) In the fixing device 20 of the first to third embodiments, the left and right shutters 56 (L and R) are provided with a plurality of shutters in order to widen the opening width. And it can also be set as the shutter mechanism composition which opens so that this plurality of shutters may overlap. That is, by moving the plurality of shutters in accordance with the opening operation of the shutter mechanism 54, the area of the surface for changing the opening width of the blower opening of the shutter mechanism is reduced.

  FIG. 17 is a schematic view of a configuration in which the left and right shutters are respectively two shutters 56L1 and 56L2 and 56R1 and 56R2 (two shutters on one side). (A) shows a state in which the left and right air outlets 51 (L and R) are fully closed by the closing movement 56a of the two shutters 56L1 and 56L2 and 56R1 and 56R2, respectively, along with the closing operation of the shutter mechanism 54 There is. In (b), when the two shutters 56L1 and 56L2, 56R1 and 56R2 overlap with the opening operation of the shutter mechanism 54 and the opening movement 56b is performed, the left and right air vents 51 (L and R) are fully opened. Is shown.

  Arrows 56L1a, 56L2a, 56R1a, 56R2a indicate the closing movement directions of the shutters 56L1, 56L2, 56R1, 56R2. Arrows 56L1b, 56L2b, 56R1b, 56R2b indicate the opening movement directions of the shutters 56L1, 56L2, 56R1, 56R2. The moving speed at the time of opening and closing movement of the shutters 56L1 and 56R1 is configured to be double speed of the shutters 56L2 and 56R2.

  In the one-side two-shutter configuration in FIG. 17, the partitions are provided on the shutter located on the outer side in the longitudinal direction of the film 33 among the two-side shutters on one side. That is, in FIG. 17, for the air outlet 51L on the L side, the partition 61 is provided so as to be integral with the shutter 56L1 on the outer side (end side) of the film 33 in the longitudinal direction. The partition 61 can move in the left-right direction together with the shutter 56L1.

  Further, in FIG. 17, with respect to the air outlet 51R on the R side, a partition 61 is provided so as to be integral with the shutter 56R1 on the outer side (end side) of the film 33 in the longitudinal direction. The partition 61 can move in the left-right direction together with the shutter 56R1.

  (3) Also in the fixing device 20 for transporting the sheet of FIG. 16 described above with reference to one side, the shutter mechanism 53 may be configured to have a plurality of shutter members. FIG. 18 is a schematic view of a configuration provided with two shutters 56A1 and 56A2. (A) shows a state in which the air vent 51 is fully closed by the closing movement of the two shutters 56A1 and 56A2 in accordance with the closing operation of the shutter mechanism 54. (B) shows a state in which the two shutters 56A1 and 56A2 overlap with each other and move open with the opening operation of the shutter mechanism 54 to fully open the blower ports 51 (L and R).

  Arrows 56A1a and 56A2a indicate the closing movement directions of the shutters 56A1 and 56A2, and arrows 56A1b and 56A2b indicate the opening movement directions of the shutters 56A1 and 56A. The moving speed of the shutter 56A1 at the time of opening and closing movement is mechanically configured to be double speed of the shutter 56A2.

  (4) Further, in the fixing device of the one-side single-shutter configuration of Embodiments 1 to 3, the shutter members 55 (L · R) of the left and right air outlets 51 (L · R) along with the opening operation of the shutter mechanism 54 Can also be configured to move in an overlapping manner. FIG. 19 is a schematic view showing this example. (A) shows a state in which the left and right air outlets 51 (L and R) are fully closed by the closing movement 56La and 56Ra of the left and right shutters 56 (L and R), respectively. (B) when the two left and right shutters 56 (L, R) overlap with the opening operation of the shutter mechanism 54 and are moved open 56 Lb, 56 Rb so that the air vents 51 (L, R) are fully open Is shown.

  Although the shutter mechanism 54 having the drive member for transmitting the drive to the shutter 56 is omitted in each of the schematic views of FIGS. 17 to 20, it may be appropriately configured by a rack-pinion mechanism or the like as in the first embodiment.

<< Other matters >>
1) The fixing mechanism section 20A is not limited to the belt heating type and pressure rotating body driving type of the above-described embodiment, and may be a heat roller type or another type. An electromagnetic induction heating system can also be used.

  2) As the fixing device 20, an apparatus for heating and fixing an unfixed toner image formed on a sheet has been described as an example, but the present invention is not limited thereto. For example, it may be a device (also referred to as a fixing device in this case) that increases the gloss (glossiness) of the image by heating and re-fixing the toner image temporarily attached to the sheet. That is, for example, a device for fixing a semi-fixed toner image on a sheet, or a device for applying a heat treatment to a fixed image may be used. Therefore, the fixing device mounted on the image forming apparatus may be, for example, a surface heating device that adjusts the gloss and surface properties of the image.

  3) The image forming apparatus described by taking the printer 100 as an example is not limited to an image forming apparatus that forms a color image, and may be an image forming apparatus that forms a monochrome image. Further, the image forming apparatus can be implemented in various applications such as a copying machine, a facsimile machine, and a multifunction machine having a plurality of these functions in addition to necessary equipment, equipment, and a housing structure.

  4) In the above description, for convenience, handling of the recording material (sheet) P is described using terms related to paper such as sheet passing, sheet feeding, sheet discharging, sheet passing portion, non-sheet passing portion, etc. It is not limited to paper. The recording material P is a sheet-like recording medium (media) on which a toner image can be formed by the image forming apparatus. For example, regular or irregular type plain paper, thin paper, thick paper, high quality paper, coated paper, envelope, postcard, seal, resin sheet, OHP sheet, printing paper, formatted paper, etc. may be mentioned.

  20 · · Fixing device, 20A · · · Fixing mechanism portion, 20B · · Blowing cooling mechanism portion 31 · · · Fixing member, 32 · · Pressure roller, 33 · · · · · (film heating roller), 52 · · Cooling duct · · · · · · · · Cooling fan, 54 · · shutter mechanism, 55 · · shutter frame, 56 · · · shutter · 57 · · rack · 58 · · · · · · · · · · · · · · · · · · partition · D · · in the duct Closed space, E · · Open space in duct

Claims (11)

A heating rotating body that heats an image on a recording material at a nip, a cooling fan that cools a set region on the width direction end of the heating rotating body, and a heating air that is cooled by the cooling fan And a shutter which is moved so as to change the opening width of the air outlet according to the length of the recording material introduced into the apparatus. And a shutter mechanism provided in the fixing device,
It is a partition wall which protrudes in the inside of the duct at the end on the air outlet side of the shutter, and restricts the air path of the cooling air sent to the area via the air outlet by the cooling fan in the width direction A fixing device comprising: a partition wall which divides the inside of the duct so as to.   The said partition wall protrudes in the direction of the said fan from the side of the said heating rotary body in the inside of the said duct, and is arrange | positioned by the orthogonal | vertical direction with respect to the said width direction. Fixing device.   The partition wall protrudes inside the duct in the direction of the fan from the side of the heating rotating body, and is disposed so as to be inclined in a direction in which the opening is expanded from the heating rotating body toward the fan The fixing device according to claim 1, characterized in that   The apparatus comprises: detection means for detecting the temperature of the region of the heating rotor; and execution means for performing a cooling operation by the cooling fan when the temperature detected by the detection means rises to a set temperature. Item 4. A fixing device according to any one of items 1 to 3.   The conveyance of the recording material is a central reference conveyance at the center of the recording material width, and the air vents are disposed symmetrically with respect to the reference line of the central reference conveyance, and the shutters are respectively provided for the respective air vents. The fixing device according to any one of claims 1 to 4, wherein the fixing device is disposed.   The shutter mechanism has a plurality of shutters, and the movement of the plurality of shutters along with the opening operation of the shutter mechanism reduces the area of the surface of the shutter mechanism for changing the opening width of the blower opening. The fixing device according to any one of claims 1 to 5, wherein the fixing device is characterized.   The fixing device according to claim 6, wherein the plurality of shutters overlap and move with an opening operation of the shutter mechanism.   The recording material is conveyed on one side based on the one end side of the recording material, and the number of the air outlet is one, and the shutter is disposed to the air outlet. The fixing device according to any one of 1 to 4.   The shutter mechanism has a plurality of shutter members, and the movement of the plurality of shutters along with the opening operation of the shutter mechanism reduces the area of the surface of the shutter mechanism for changing the opening width of the blower opening. The fixing device according to claim 8, characterized in that:   10. The fixing device according to claim 9, wherein the plurality of shutter members overlap and move with the opening operation of the shutter mechanism.   The conveyance of the recording material is a central reference conveyance at the center of the recording material width, and two air outlets are provided symmetrically with respect to the reference line of the central reference conveyance, one sheet for each air outlet. The shutter mechanism provided with a shutter is arrange | positioned, and the shutter of each said blower opening overlaps and moves with the opening operation of the said shutter mechanism, It is characterized by the above-mentioned. Fixing device as described.