JP2019095532A - Fixation device - Google Patents

Abstract

To provide a fixation device having a structure of cooling a non-passage area (non-paper feeding area) of a recording material with cooling air, the fixation device capable of cooling a non-passage area regarding a recording material of various width sizes, more effectively than before.SOLUTION: A fixation device includes a fixation mechanism part of a belt heating type, and a blow cooling mechanism part. The blow cooling mechanism part is cooling means for cooling, by air blow, a temperature rise at a non-paper feeding part of the fixation mechanism part, which may occur when narrow sheets are continuously passed. The blow cooling mechanism part includes: a cooling fan 52R configured to cool a preset area on an end side in a width direction of a belt 33; a duct 51(L/R) configured to guide cooling air by the cooling fan 52R and having an air blow port; and a shutter mechanism having a shutter plate 55(L/R) configured to be moved to change an opening width of the air blow port according to a length in a width direction of a sheet. A face of the shutter plate 55(L/R) opposing the air blow port is slanted with regard to the width direction of the belt 33 so that the cooling air hitting the face is directed from a center side to the end side in the width direction of the belt 33.SELECTED DRAWING: Figure 6B

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.

  The image forming apparatus as described above forms an unfixed toner image on a sheet-like recording material (hereinafter referred to as a sheet) by the image forming means, and then fixes the toner image as a fixed image by the fixing means. There is.

  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.

  According to the technique of Patent Document 1, a cooling air is selectively blown from a cooling fan disposed in the fixing device to the non-sheet-passing area side. The technique of Patent Document 2 differs in that when the cooling air is blown from the cooling fan to the non-sheet-passing area side, the length in the width direction of the air blowing port is adjusted according to the width of the sheet to be used. The non-sheet-passing portion temperature rise is also prevented for width-sized sheets. In the technology of Patent Document 3, a cooling fan and a duct are disposed at an angle, and cooling paper is efficiently sent to the cooling area of the non-sheet passing portion even when sheets of various width sizes are sent. Prevents wraparound to the paper area.

JP-A-4-51179 JP 2003-076209 JP 2008-58378 A

  With regard to sheets, the maximum width sheets that can be used in the fixing device are large size sheets, the minimum width sheets are small size sheets, and the width sheets between large size sheets and small size sheets are medium size sheets.

  In FIG. 13A, a small-size sheet passes through the fixing nip portion N formed by the fixing roller 101 as a heating rotating body and the pressure roller 102 as a pressing rotating body in center reference conveyance at the center of the sheet width. It shows the condition when it is printed. Q is a sheet passing area of a small size sheet, and R is a non-sheet passing area generated on both left and right sides (one end side and the other end side of the fixing roller 101 in the longitudinal direction) of the sheet passing area Q.

  Further, in the left and right air blow cooling mechanisms 103 (L, R) of the fixing device, the air outlets a of the ducts 104 (L, R) having the air intake cooling fans 105 (L, R) are respectively left and right. Opposite the non-sheet passing area R · R. Further, the widths of the air blowing ports a of the ducts 104 (L and R) correspond to the widths of the non-sheet-passing areas R and R, respectively. The shutter plates 106 (L · R) are respectively moved to positions where the air outlets a of the ducts 104 (L · R) are fully opened.

  Therefore, the non-sheet passing area R · R of the fixing roller 101 generated when passing the small size sheet is cooled by the cooling air blown out from the blowing port a of the duct 104 (L · R) in the fully open state. Non-sheet-passing portion temperature rise during continuous sheet passing is prevented.

  FIG. 13 (b) shows the condition when medium size paper is passing, where Q is a paper passing area of medium size paper and R is a non-sheet passing area generated on both left and right sides of the paper passing area Q. The shutter plate 106 (L · R) is moved to a position where the opening width of the air outlet a of the duct 104 (L · R) is narrowed according to the width of the medium size sheet. Therefore, the non-sheet passing area R · R of the fixing roller 101 generated when passing a medium size sheet is cooled by the cooling air blown out from the air outlet a whose opening width of the duct 104 (L · R) is adjusted, and the medium size The temperature rise of the non-sheet passing portion at the time of continuous sheet passing is prevented.

  FIG. 13C shows the state when large-size paper is passed. In this case, the temperature of the non-sheet-passing portion does not occur in the fixing roller 101, so the shutter plate 106 (L · R) is a duct 104. It moves to the position which made the blowing port a of (L · R) fully closed. Therefore, the fixing roller 101 is not cooled by the cooling air.

  In this embodiment, when the shutter plate 106 (L · R) for adjusting the opening width of the air outlet a of the duct 104 (L · R) is in the position as shown in (b), the shutter plate 106 (L・ The cooling air hits the inner wall of R) almost perpendicularly. Therefore, the flow rate of the cooling air indicated by the streamline Z is lost, and a sufficient cooling effect of the non-sheet-passing regions R and R can not be obtained.

  Furthermore, as shown in (a), a part of the cooling air that has hit the non-sheet-passing zone R · R of the fixing roller 101 turns around to the sheet-passing zone Q as indicated by the flow line X and passes. The temperature of the fixing roller portion corresponding to the widthwise end of the paper area Q also decreases. The same applies to (b).

  With a continuous sheet of about 50 sheets, the temperature decrease of the fixing roller portion corresponding to the widthwise end of the sheet passing area Q due to the wraparound wind X is also small, and the temperature difference with the longitudinal central portion of the fixing roller 101 also almost occurs. There is not. However, at the time of continuous sheet passing of a larger number of sheets, the temperature drop of the fixing roller portion corresponding to the width direction end of the sheet passing area Q due to the wraparound wind X is accumulated and an abnormal image such as fixing failure of the image end is generated was there.

  FIGS. 14 (a) to 14 (c) show cooling fans 105 (L and R) and ducts 104 (L and L) of the blower cooling mechanism 103 (L and R) in order to improve the problems of the apparatus of the reference example of FIG. R) is placed at an angle. φ is the crossing angle between the streamline Y of the cooling air and the direction perpendicular to the width direction (longitudinal direction, rotational axis direction) OO of the fixing roller 101. As a result, the cooling air can be efficiently sent to the cooling area of the non-sheet-passing portions R and R, and the cooling air can be prevented from flowing around the sheet-passing area Q, even for sheets of various width sizes.

  That is, the cooling fans 105 (L · R) and the ducts 104 (L · R) are inclined so as to blow air from the central reference conveyance line S (virtual line) of the sheet toward the sheet passing end. Therefore, while the cooling fans 105 (L · R) and the ducts 104 (L · R) are disposed with a small space, a wide cooling area of the non-sheet-passing areas R · R can be secured. Moreover, since the duct 104 (L · R) is formed along the flow line Y direction of the cooling air generated from the cooling fan 105 (L · R), the loss of the cooling air is also very small.

  Further, since the streamline Y of the cooling air is formed obliquely from the central reference conveyance line S to the non-sheet-passing area R and R, the stream line near the fixing roller 101 is also directed toward the end. It is possible to prevent the cooling air from flowing around the end of Q. Therefore, the image defect generated due to the temperature decrease of the sheet passing area Q does not occur. Furthermore, even when the shutter plate 106 (L · R) is controlled to the position as shown in FIG. 14 (b), the cooling air obliquely strikes the inner surface of the shutter plate, so streamline Ya along the inner surface of the shutter plate. The cooling air flows like.

  However, in recent years, there has been a growing demand for increasing the sheet conveyance speed, and in that case, there is a concern that the temperature rise speed in the non-sheet-passing area will increase and the cooling air volume will be insufficient. Therefore, further improvement in cooling efficiency is required.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to fix a non-passing area (non-sheet-passing area) of a recording material by cooling air with various width sizes. Another object of the present invention is to cool the non-passing area more efficiently than in the prior art.

  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 member which is moved so as to change according to the width direction length of the recording material, the shutter member being between the fully open and the fully closed opening width of the blower opening The cooling air that strikes the surface of the shutter member facing the air outlet in the state of being moved to the predetermined opening width of the heating member from the center side in the width direction of the heating rotating body to the end side Said face is said And it is inclined with respect to the width direction of the heat rotation member.

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

Cross-sectional model view of the fixing device in the embodiment An exploded perspective model view of the fixing mechanism portion and the air blowing and cooling mechanism portion of the fixing device Partial cutaway front view of fixing mechanism Vertical front view of fixing mechanism An exploded perspective view of the blower cooling mechanism Operation explanatory drawing of the shutter board in Example 1 (the 1) Same as above (Part 2) Same as above (No. 3) Block diagram of control system of fixing device Cross-sectional model view of an example of an image forming apparatus Structural schematic diagram of the shutter mechanism in Example 2 (the 1) Same as above (Part 2) Same as above (No. 3) Same as above (4) An explanatory view of a reference example device (part 1) An explanatory view of a reference example device (part 2)

  Hereinafter, embodiments of the present invention will be described in detail based on the attached drawings.

Example 1
(1) Image Forming Unit FIG. 8 is a schematic longitudinal sectional view showing a schematic configuration of an electrophotographic full color printer as an example of an image forming apparatus equipped with a fixing device according to the present invention. The printer 100 performs an image forming operation according to input image information of 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.

  The image forming unit 100A of the printer 100, which forms a toner image on a recording material (hereinafter referred to as a sheet of paper) P, forms toner images of yellow (Y), magenta (M), cyan (C), and black (Bk). Four image forming stations 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 9 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 of paper P are fed one by one from the preselected sheet feeding section of the multistage cassettes 10 to 12 or the manual feeding tray 13 by the rotation of the sheet feeding roller 14. The sheet P passes through the conveyance path 15 having the registration roller pair 16 and is introduced to the secondary transfer portion 17 formed by the belt 8 and the secondary transfer roller 9, and receives the secondary transfer of the toner image from the belt 8 side. . Then, the sheet P is guided from the secondary transfer portion 17 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 24, 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 17 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 In the following description, the longitudinal direction of the fixing device 20 or members constituting the fixing device 20 is a direction parallel to the direction orthogonal to the sheet conveying direction in the sheet conveying road surface. With regard to the fixing device 20, the front is the surface on which the sheet is introduced, and the left and right are the left or the right when the device 20 is viewed from the front. The sheet width is the sheet size in the direction orthogonal to the sheet conveyance direction on the sheet surface.

  FIG. 1 is an enlarged cross-sectional view of the fixing device 20 of the printer 100 of FIG. The fixing device 20 is roughly divided into a belt heating type fixing mechanism portion 20A and an air blowing and cooling mechanism portion 20B.

(2-1) Fixing Mechanism Section First, the outline of the fixing mechanism section 20A will be described mainly with reference to FIG. 1 to FIG. 4 and FIG. 2 is an exploded perspective view of the fixing mechanism portion 20A and the air blowing and cooling mechanism portion 20B, FIG. 3 is a schematic front view of the fixing belt assembly of the fixing mechanism portion 20A and the pressure roller, FIG. Is a block diagram of a control system of the fixing device.

  The fixing mechanism portion 20A basically has on-demand of belt (film) heating method / pressure rotary body driving method (tensionless type) disclosed in Japanese Patent Application Laid-Open Nos. 4-44075 to 44083 and 4-204980 to 204984. It is a fixing device.

  31 is a fixing belt assembly, and 32 is an elastic pressure roller as a pressure roller. The fixing nip portion N is formed by pressure contact between the fixing belt 33 of the fixing belt assembly 31 and the pressure roller 32. The sheet P is conveyed while being nipped by the fixing nip portion N, and the image t formed on the sheet (on the recording material) is heated by the fixing belt assembly 31.

  In the fixing belt assembly 31, reference numeral 33 denotes a cylindrical (endless belt-like, sleeve-like) as a heating rotator, and is a flexible fixing belt (hereinafter abbreviated as a belt). Reference numeral 34 denotes a belt guide member (hereinafter abbreviated as a guide member) having heat resistance and rigidity with a substantially semicircular wedge shape in 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 on the outer surface of the guide member 34 in a recessed groove provided along the longitudinal direction of the member. Yes. The belt 33 is loosely fitted around the guide member 34 to which the heater 35 is attached.

  Reference numeral 36 denotes a rigid pressure stay (hereinafter abbreviated as "stay") having a U-shaped 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 respectively project outward from the left and right openings of the belt 33 in a predetermined manner (FIG. 4). An end holder 37 is fitted to the outward projections 36a of the left and right ends of the stay 36, and 37a is a flange of each of the left and right end holders 37.

  The belt 33 is usually a composite layer structure in which a heat resistant resin belt or metal belt is used as a base layer and an elastic layer, a mold release layer and the like are added to the outer peripheral surface thereof. Generally, the heat transfer member has a high thermal conductivity and low heat capacity.

  The heater 35 is a low-heat-capacity, horizontally long, thin linear heating body whose longitudinal direction is a direction orthogonal to the moving direction of the belt 33 and the paper P. The basic structure is a heater substrate of a ceramic material such as aluminum nitride alumina or the like, and a conductive heat generating layer such as silver-palladium formed on the surface of the substrate. Since various ceramic heaters are known, the detailed description thereof is omitted.

  The pressure roller 32 has a core metal 32a provided with an elastic layer 32b of silicone rubber or the like to reduce the hardness. In order to improve the surface property, 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 disposed so that the left and right end portions of the cored bar 32a are rotatably held by bearings via bearing members 39 between the left and right side plates 38 (L and R) of the apparatus frame 38.

  The fixing belt assembly 31 is arranged parallel to the pressure roller 32 with the heater 35 side facing the pressure roller 32. Then, the left and right end holders 37 are respectively urged in the axial direction of the pressure roller 32 with a predetermined force F by a pressure mechanism (not shown). Thus, the surface of the heater 35 is pressed against the pressure roller 32 against the elasticity of the elastic layer 32b through the belt 33, and a fixing nip portion having a predetermined width in the sheet conveyance direction necessary for heat fixation. (Hereinafter, abbreviated as a nip portion) N is formed.

  The pressing mechanism has a pressure releasing mechanism, and the pressure is released at the time of jam processing or the like so that the sheet P held in the nip portion N can be easily removed. Reference numerals 40 and 41 denote an entrance guide and a fixing discharge roller assembled to the apparatus frame 38. The entrance guide 40 guides the sheet P so that the sheet P which has been guided by the vertical guide 19 through the secondary transfer portion 17 and entered the fixing device 20 is correctly guided to the nip portion N.

  G is a drive gear fixed to one end 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 the arrow in FIG. By the rotational drive of the pressure roller 32, a rotational force acts on the belt 33 by the frictional force at the nip portion N between the pressure roller 32 and the outer surface of the belt 33. As a result, the belt 33 rotates on the outer periphery of the guide member 34 in the counterclockwise direction of the arrow (pressure roller driving method) while the inner surface slides in close contact with the heater 35 at the nip portion N.

  The belt 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 and limit the movement of the belt end on the side when the rotating belt 33 moves to the left or right along the length of the guide member 34. . Grease (lubricant) is applied to the inner surface of the belt 33 to ensure the slidability of the belt 33 with respect to the heater 35 and the guide member 34.

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

  TH1 and TH2 are two main and sub thermistors as first and second temperature detection means (detection means for detecting temperature). The main thermistor TH1 is disposed in contact with the back of the heater at a substantially central position in the longitudinal direction of the heater 35 so as to detect the temperature of the heater at which a sheet of any size can be passed. .

  The sub-thermistor TH2 is a belt portion corresponding to the non-sheet passing portion (area at the width direction end portion of the belt 33) when passing a sheet having a width smaller than the maximum width sheet capable of passing through the apparatus. It is disposed in resilient contact with the inner surface of the belt 33 so as to detect the temperature. Specifically, the sub-thermistor TH2 is supported by the free end of a leaf spring-shaped elastic support member 42 whose base is fixed to the guide member 34. Then, the sub-thermistor TH2 is disposed in elastic contact with the inner surface of the belt 33 by the elasticity of the elastic support member 42.

  The heater 35 is energized from a heater drive circuit 92 (FIG. 7) as a power supply unit through a feeder line and a connector (all not shown) to the heat generating layer provided on the heater substrate surface. . As a result, the heat generating layer generates heat, and the temperature of the heater 35 rapidly rises over the entire effective heat generation width of the heater in the longitudinal direction.

  The heater temperature is detected by the main thermistor TH1, and electrical information on the heater temperature is input to the control circuit unit 200 via the A / D converter 81. Further, the temperature of the fixing belt 33 is detected by the sub-thermistor TH2, and electrical information on the temperature of the fixing belt 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. That is, the temperature control of the heater 35 is controlled so that the heater temperature detected by the main thermistor TH1 is maintained at a predetermined fixing temperature. Then, the control circuit unit 200 controls the motor drive circuit 91 based on the print signal from the external host device 300 or another control signal to start the rotational drive of the pressure roller 32. Further, the heater drive circuit 92 is controlled to start the heat-up of the heater 35.

  With the rotational speed of the belt 33 steady and the temperature of the heater 35 rising 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 40 Introduced. The toner image bearing surface side of the sheet P faces the belt 33. The sheet P is in close contact with the heater 35 via the belt 33 at the nip portion N, and moves through the nip portion N together with the belt 33. In the movement passing process, heat is applied to the sheet P by the belt 33 heated by the heater 35, and the toner image t is heated and fixed on the sheet surface. The sheet P having passed through the nip portion N is separated from the surface of the belt 33 and discharged and conveyed.

(2-2) Blowing Cooling Mechanism Part Next, the blowing cooling mechanism part 20B will be described mainly with reference to FIG. 5 to FIG. The blower cooling mechanism unit 20B cools the non-sheet-passing portion temperature rise of the fixing mechanism unit 20A by blowing air, which occurs when continuously passing a sheet having a narrower width than a sheet of the maximum width that can be used for sheet passing into the apparatus. It is a means.

  The blower cooling mechanism unit 20B guides the cooling fan 52 (L · R) for cooling the set region on the width direction end side of the belt 33 and the cooling air by the cooling fan to the belt 33, thereby cooling the region The duct 51 (L · R) is provided with an air outlet a for setting. In addition, the blower cooling mechanism unit 20B is a shutter mechanism including a shutter member 55 (L and R) which is moved so as to change the opening width of the blower opening according to the length in the width direction of the sheet P introduced into the apparatus. It has 53.

  FIG. 5 is an exploded perspective view of the air blowing and cooling mechanism unit 20B. 6A to 6C are diagrams for explaining the operation of the shutter member. The air blowing and cooling mechanism portion 20B has a left side duct 51L in which an air blowing port a is formed opposite to a portion on the left side in the longitudinal direction of the belt 33, and a left side cooling fan 52L which blows a cooling air to the duct 51L. Further, the right side duct 51R is formed with an air outlet a facing the portion on the right side in the longitudinal direction of the belt 33, and the right side cooling fan 52R for blowing the cooling air to the duct 51R. Further, the shutter mechanism 53 as an opening width adjusting mechanism is provided to adjust the opening width of the air outlet a of the left duct 51L and the air outlet a of the right duct 51R.

  The cooling fan (hereinafter abbreviated as a fan) 52 (LR) employs an axial fan which is less expensive than a sirocco fan or a cross flow fan.

  The shutter mechanism 53 includes a shutter frame 54, window holes b respectively provided on left and right sides of the frame in the longitudinal direction, a pair of movable shutter members 55 (L and R) on the left and right, shutter motor M2, shutter plate position detection Means 55a, 55b, PH and the like are included.

  The shapes and sizes of the left and right window holes b and b correspond to the shapes and sizes of the air outlets a and a of the duct 51 (L and R), respectively. The ducts 51 (L and R) are fixed to the substrate 54 with the air outlets a corresponding to the left and right window holes b of the substrate 54, respectively.

  The pair of left and right movable shutter members (hereinafter referred to as shutter plates) 55 (LR) is disposed on the surface of the substrate 54 opposite to the side where the ducts 51 (LR) are fixed and disposed. Yes. The left shutter plate 55L moves so as to adjust the opening width of the left window hole b, that is, the air outlet a of the left duct 51L. The right shutter plate 55R moves so as to adjust the opening width of the right window hole b, that is, the air outlet a of the right duct 51R.

  The left and right shutter plates 55 (L and R) are connected by a rack-pinion mechanism (not shown) as a drive member for transmitting a drive thereto. Then, the pinion is rotationally driven in the forward and reverse directions by the shutter motor (pulse motor) M2, so that the opening width of the air outlet a of the left and right ducts 51 (L and R) is adjusted in the same manner in an interlocking manner. Move to

  6A to 6C, in order to avoid complication, the blower and cooling mechanism unit 20B includes only the left and right ducts 51 (L and R), the fans 52 (L and R), and the shutter plates 55 (L and R). showed that. 6A to 6C are cross-sectional views in the direction in which the thickness direction of the shutter plate 55 is viewed and in the direction in which the longitudinal direction of the belt 33 is viewed.

  FIG. 6A shows a state in which the left and right shutter plates 55 (L and R) are moved to positions where the air outlets a of the left and right ducts 51 (L and R) are fully opened. FIG. 6C shows a state in which the left and right shutter plates 55 (L and R) are moved to positions where the air outlets a of the left and right ducts 51 (L and R) are fully closed. FIG. 6B shows the positions where the left and right shutter plates 55 (L and R) change the opening width of the air outlet a of the left and right ducts 51 (L and R) to a predetermined opening width between full open and full close, respectively. Indicates the state of being moved to

  The feature is that, as shown in FIG. 6B, the surface of the shutter plate 55 (LR) facing the side facing the air outlet a faces the cooling air from the center side in the width direction of the belt 33 to the end side. Is inclined with respect to the width direction of the belt 33. In the first embodiment, the shutter plate 55 (L and R) has the inclined surface 55La and 55Ra on the side facing the air outlet a. That is, in the state of FIG. 6B, the cooling air that strikes the surface (inner wall surface of the shutter plate) of the shutter plate 55 (L and R) with respect to the air outlet a is directed from the widthwise center side to the end side of the belt 33 The surface is inclined with respect to the width direction of the belt 33.

  Y is a streamline of the cooling air blown from the fan 52 (L · R) to the duct 51 (L · R). Further, the duct 51 (L · R) is disposed along the direction of air flow of the fan 52 (L · R), that is, the streamline Y of the cooling air, and is inclined so as to guide it to the sheet width direction end. That is, the fan 52 (L · R) and the duct 51 (L · R) are inclined with respect to the width direction of the belt 33 so that the cooling air is blown obliquely from the center side of the width direction of the belt 33 toward the end. Installed. In the present embodiment, the rotation axis of the fan 52 is parallel to the streamline Y.

  In FIG. 6B, an intersection angle between a surface of each of the left and right shutter plates 55 (L and R) opposite to the air outlet a and a virtual line in a direction perpendicular to the width direction OO of the belt 33 is φ1.

  Here, the crossing angle φ1 is defined as the following angle. The shutter plate 55 on the L side and the duct 51 will be described as an example, but the same applies to the R side. A direction perpendicular to the width direction OO is a normal line α, and an intersection of the normal line α and the intersection line of the shutter surface is a point β. Starting from this point β, a portion of the normal α on the side extending from the shutter surface to the duct side corresponding to the shutter surface is taken as a reference half line γ. The reference half line γ is 0 °, and the point β is centered. Of the shutter surface, a portion extending toward the center in the width direction of the belt 33 beyond the point β forms an intersection angle φ1 with the reference half line γ.

  The crossing angle between the extension direction (direction of the rotation axis of the fan 52) of the duct 51 (L · R) toward the belt 33 and the direction (normal line α described above) perpendicular to the width direction of the belt 33 is φ2.

  The crossing angle φ1 is 90 °> φ1, and the crossing angle φ2 is 80 ° ≧ φ2 ≧ 10 °. The relationship between the crossing angle φ1 and the crossing angle φ2 is set in the range of 40 ° ≧> 10 °.

  The values of the crossing angles φ1 and φ2 set in the first embodiment are set experimentally. When (φ1−φ2) is less than 10 °, the shutter plate 55 (L · R) becomes substantially parallel to the streamline Y of the cooling air. Therefore, it is difficult to prevent the cooling air from flowing out to the sheet passing area Q of the belt 33. Further, when (φ1−φ2) exceeds 40 °, the cooling air Yb easily hits the inner wall surface of the shutter plate 55 (L · R), so the cooling air Yb does not easily follow the shutter plate 55 (L · R) Cooling efficiency does not go up.

  That is, the flow line Y of the cooling air from the cooling means 51, 52 for cooling the outside of the paper conveyance area of the belt 33, which is a heating rotator, toward the belt 33 hits the inner wall surface of the shutter plate 55 (L, R). At times, do not lose air volume. Therefore, the shutter plate 55 (L · R) is configured to have an inclination with respect to a direction perpendicular to the width direction OO of the belt 33.

  Here, regarding the sheets, the maximum width sheets that can be used in the fixing device 20 are large size sheets, the minimum width sheets are small size sheets, and the width sheets between large size sheets and small size sheets are medium size sheets I assume.

  FIG. 6A shows the condition when small size paper is passed, where Q is a small size paper passing area and R is a non-passing area generated on the left and right sides of the paper passing area Q. The air outlets a of the left and right ducts 51 (L, R) respectively face the non-sheet-passing areas R, R on the left and right. Further, the widths of the air blowing ports a of the ducts 51 (L and R) correspond to the widths of the non-sheet-passing regions R and R on the left and right, respectively.

  The left and right shutter plates 55 (L and R) are moved to positions where the air outlets a of the left and right ducts 51 (L and R) are fully opened. Therefore, the left and right non-sheet-passing areas R and R of the belt 33 generated when passing small-size sheets are cooled by the cooling air blown out from the fully open air ports a of the left and right ducts 51 (L and R), respectively. The temperature rise of the non-sheet-passing portion at the time of continuous sheet-passing of the small size sheet is prevented.

  FIG. 6B shows the condition when medium size paper is passed, where Q is a paper passing area of medium size paper and R is a non-sheet passing area generated on both the left and right sides of the paper passing area Q. The left and right shutter plates 55 (L and R) are moved to positions where the opening widths of the air outlets a of the left and right ducts 51 (L and R) are narrowed according to the width of the medium size sheet. Therefore, the left and right non-sheet-passing areas R and R of the belt 33 generated when passing medium-size sheets are respectively cooled by the cooling air blown out from the air outlet a whose opening width of the left and right ducts 51 (L and R) is adjusted. As it is cooled, the non-sheet-passing portion temperature rise during continuous sheet-passing of medium-size sheets is prevented.

  FIG. 6C shows the condition when large size paper is passed. In this case, since the temperature rise of the non-sheet-passing portion does not occur in the belt 33, the left and right shutter plates 55 (L and R) are respectively left and right. Is moved to a position in which the air outlet a of the duct 51 (L · R) is fully closed. Therefore, the belt 33 is not cooled by the cooling air.

  In the case of the large-size sheet passing, control may be made to hold the fan 52 (L · R) in the stopped state. In this case, control may be performed to move the left and right shutter plates 55 (L and R) to the fully closed position with respect to the air outlets a of the left and right ducts 51 (L and R), respectively. .

  The left and right shutter plates 55 (L and R) are controlled by a moving mechanism (not shown) so as to move to a position corresponding to the width of the sheet used for sheet passing. As a result, the air outlets a of the left and right ducts 51 (L and R) are adjusted to an opening width optimum for the sheet width to be passed, and air cooling is performed with the optimum non-sheet passing width.

  Specifically, a plurality of edges determined corresponding to sheets of various width sizes are formed at the bending edge 55a (FIG. 1 and FIG. 5) of one shutter plate 55R of the left and right shutter plates 55 (L and R). The part 55b is provided. In addition, a photosensor PH for detecting the edge portion 55b is fixed to the shutter frame 54 and provided. The edge detection information of the photo sensor PH is input to the control circuit unit 200 via the A / D converter 83.

  The control circuit unit 200 controls the shutter motor M2 to rotate in the forward or reverse direction so that the edge portion 55b corresponding to the width size information of the sheet to be used input from the external host device 300 or the like is detected by the photo sensor PH. The shutter plate 55 (L · R) is moved. The driving of the shutter motor M2 is stopped when the edge portion 55b corresponding to the width size information of the sheet to be used is detected by the photo sensor PH. As a result, the left and right shutter plates 55 (L and R) are moved to positions corresponding to the width of the sheet used for sheet passing.

  Next, the operation of the left and right fans 52 (L and R) in the fixing device 20 of this embodiment will be described. When continuously fixing medium- and small-size sheets smaller in width than the above-mentioned large-size sheets at the time of image formation, the temperature of the non-sheet-passing area R rises. At this time, the sub-thermistor TH2 as a second temperature detection unit detects the inner surface temperature of the belt portion corresponding to the non-sheet-passing area R.

  The control circuit unit (execution means) 200 controls the shutter motor drive circuit 93 when the sub thermistor TH2 detects a predetermined temperature, that is, when the temperature detected by the sub thermistor TH2 rises to a predetermined set temperature. That is, the shutter motor M2 moves the left and right shutter plates 55 (L and R) to a position corresponding to the width of the sheet. In addition, the control of the cooling fan drive circuit 94 starts the operation of the left and right fans 52 (L and R). That is, the control circuit unit 200 performs the cooling operation. This suppresses the temperature rise in the non-sheet passing area.

  Then, the fan 52 (L · R) is cooled by the cooling air so that the operation of the fan 52 (L · R) is stopped when the temperature detected by the sub thermistor TH2 drops to a predetermined temperature.

  The temperature range of the ON-OFF control based on the temperature detected by the sub thermistor TH2 of the fan 52 (L · R) is controlled to be changed according to the operating condition of the fan. The temperature range of the ON-OFF control of the fan 52 (L · R) in this embodiment is controlled as follows, for example, when 100 sheets of B4 size paper (medium size paper) are continuously passed. .

  That is, when the number of sheets to be passed is 0 to 30, the operation start temperature of fan 52 (L · R) is detected when the detection temperature of sub thermistor TH2 reaches 200 ° C., the stop temperature of the fan is detection of sub thermistor TH2 It takes place when the temperature reaches 190 ° C. And at the time of 31 to 60 sheets, the operation temperature of the fan is similarly performed at a start temperature of 205 ° C. and a stop temperature of 195 ° C. The fan start temperature and stop temperature are raised by 5 ° C. for every 30 sheets thereafter.

  The fans 52 (L · R) and the ducts 51 (L · R) are inclined so as to blow air from the center of the sheet to the end of the sheet. Therefore, while the fans 52 (L · R) and the ducts 51 (L · R) are disposed in a space-saving manner, a wide cooling area of the non-sheet-passing area can be secured. Moreover, since the duct 51 (L · R) is formed along the flow line Y direction of the cooling air generated from the fan 52 (L · R), the loss of the cooling air is also very small.

  Further, since the flow line Y of the cooling air is formed obliquely from the sheet passing center to the non-sheet passing area, the stream line in the vicinity hitting the belt 33 is also directed toward the end, and to the end of the sheet passing area Q. It is possible to prevent the wraparound of the cooling air. Therefore, the image defect caused by the temperature drop of the sheet passing area does not occur.

  Furthermore, even when the shutter plate 55 (L · R) is controlled to the position as shown in FIG. 6B, the shutter plate 55 (L · R) is inclined. Therefore, since the cooling air is obliquely applied, the cooling air flows along the inner surface of the shutter like Yb, and the belt 33 can be cooled more efficiently, and the loss of the cooling air can be reduced. .

  That is, the flow line Y of the cooling air from the cooling means 51, 52 for cooling the outside of the paper conveyance area of the belt 33, which is a heating rotator, toward the belt 33 hits the inner wall surface of the shutter plate 55 (L, R). At times, do not lose air volume. Therefore, the shutter plate 55 (L · R) is configured to have an inclination with respect to a direction perpendicular to the width direction OO of the belt 33.

Example 2
(1) In the fixing device 20 of the first embodiment, the conveyance of the sheet is the center reference conveyance of the sheet width center. Further, two air outlets a are installed symmetrically with respect to the reference line S of the central reference conveyance, and shutters provided with one shutter plate 55 (L · R) for each air outlet. A mechanism 53 (L · R) is disposed (one-shutter configuration on one side).

  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. 9, the fixing device 20 is one-side reference conveyance based on one end side of the sheet, and there is one air outlet a, and one shutter for this air outlet. The shutter mechanism 53 having the plate 55 may be disposed.

  (A) shows a state where the shutter plate 55 is moved to a position where the air outlet a is fully closed, and (b) shows a state where the shutter plate 55 is moved to a position where the air outlet a is fully open ing. SA indicates a reference line (virtual line) for one-side reference conveyance, arrow b indicates the closing movement direction of the shutter plate 55, and arrow c indicates the opening movement direction.

  (2) In the fixing device 20 of the first embodiment, in order to widen the opening width of the shutters of the left and right shutter mechanisms 53 (L, R), a plurality of shutter members are provided in the left and right shutter mechanisms 53 (L, R). Prepare. And it can also be set as the shutter mechanism composition which opens so that this shutter member of a plurality of sheets may overlap. That is, the shutter mechanism 53 has a plurality of shutter members, and the movement of the plurality of shutter members along with the opening operation of the shutter mechanism reduces the area of the surface for changing the opening width of the air outlet of the shutter mechanism. It is a structure.

  FIG. 10 is a schematic view of a configuration in which two shutter members 55L1 and 55L2 and 55R1 and 55R2 are provided in the left and right shutter mechanisms 53 (L and R) (two shutter configuration on one side). (A) shows a state in which the left and right air outlets a are fully closed by the closing movement b of the two shutter members 55L1 and 55L2 and 55R1 and 55R2 in accordance with the closing operation of the shutter mechanism 53. (B) shows the state in which the two shutter members 55L1 and 55L2 and 55R1 and 55R2 overlap and open with the opening operation of the shutter mechanism 53 and the left and right air outlets a are fully open. .

  The moving speed at the time of opening and closing movement of the shutter members 55L1 and 55R1 is configured to be double speed of the shutter members 55L2 and 55R2. In this configuration, in the discussion of the crossing angle, the shutter surface of the shutter member on the center side in the width direction of the belt 33 is used as the shutter angle.

  (3) Also in the fixing device 20 for conveying the sheet of FIG. 9 on one side based on the reference, the shutter mechanism 53 may be configured to have a plurality of shutter members. FIG. 11 is a schematic view of a configuration provided with two shutter members 55A1 and 55A2. (A) shows a state in which the air blowing port a is fully closed by the closing movement b of the two shutter members 55A1 and 55A2 in accordance with the closing operation of the shutter mechanism 53. (B) shows a state in which the two shutter members 55A1 and 55A2 overlap with each other and open and move along with the opening operation of the shutter mechanism 53, and the air outlet a is fully opened.

  (4) Further, in the fixing device of the one-side single-shutter configuration of Embodiment 1, the shutter members 55 (L and R) of the respective air outlets a on the left and right overlap with each other and move along with the opening operation of the shutter mechanism 53. It can also be FIG. 12 is a schematic view showing this example. (A) shows a state in which the left and right air outlets a are fully closed by the closing movement b of the left and right shutter members 55 (L and R), respectively. (B) shows a state in which the two left and right shutter members 55 (L and R) overlap with each other and open and move along with the opening operation of the shutter mechanism 53, and the air blowing ports a are fully opened.

  Although the shutter mechanism 53 having the drive member for transmitting the drive to the shutter plate is omitted in each of the schematic views of FIGS. 9 to 12, it may be appropriately configured by, for example, a rack-pinion mechanism or the like.

<< 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 a fixing device, an apparatus for heating and fixing an unfixed toner image formed on a sheet has been described as an example, but the 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, P · · · Recording material, t · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · rotating body rotating N, Nip · 51 · · · dust · a · · · · · 52 · · · cooling fan Shutter mechanism, 55 · · Shutter member

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 member moved so as to change the opening width of the air outlet according to the length in the width direction of the recording material introduced into the apparatus. And a shutter mechanism provided in the fixing device,
In a state in which the shutter member is moved to a position where the opening width of the air blowing port is changed to a predetermined opening width between full opening and full closing, the cooling air striking the side of the shutter member facing the air blowing port The fixing device is characterized in that the surface is inclined with respect to the width direction of the heating rotating body so as to face from the center side in the width direction of the heating rotating body to the end side. When the shutter member is moved to a position where the opening width of the air blowing port is changed to a predetermined opening width between full opening and full closing, the intersection of the surface and a direction perpendicular to the width direction of the heating rotator Assuming that the angle is φ1, and the crossing angle between the extension direction of the duct toward the heating rotator and the direction perpendicular to the width direction of the heating rotator is φ2,
The crossing angle φ1 is 90 °> φ1,
The crossing angle φ2 is 80 ° ≧ φ2 ≧ 10 °,
The fixing device according to claim 1, wherein the relationship between the crossing angle φ1 and the crossing angle φ2 is set in the range of 40 ° ≧ 10 °.   The duct is arranged to be inclined with respect to the width direction of the heating rotor so that the cooling air is blown obliquely from the center side in the width direction of the heating rotor toward the end side. The fixing device according to claim 1.   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 two air outlets are provided symmetrically with respect to the reference line of the central reference conveyance, and the shutter mechanism is provided for each air outlet. 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 shutter members, and the movement of the plurality of shutter members 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 provided.   The fixing device according to claim 6, wherein the plurality of shutter members 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 blowing port is one, and the shutter mechanism is disposed to the air blowing port. The fixing device according to any one of Items 1 to 4.   The shutter mechanism has a plurality of shutter members, and the movement of the plurality of shutter members 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,   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 member is arrange | positioned, and the shutter member of each said ventilation opening overlaps and moves with the opening operation of the said shutter mechanism, It is characterized by the above-mentioned. The fixing device according to claim 1.