JP2022113297A - Fixing device - Google Patents

Abstract

To provide a fixing device that, when cooling air hits a non-paper feed area of a fixing film, can prevent a reduction in temperature of a paper feed area of the fixing film.SOLUTION: A fixing cover 45 having second rectification ribs 44L formed in a ventilation hole 38L is interposed so as not to overlap first rectification ribs 43L formed in a blow-out port 31L of a cooling unit 250, thereby causing cooling air to hit a non-paper feed area of a fixing film 13. The first rectification ribs 43L and the second rectification ribs 44L are formed to be substantially orthogonal to a width direction. This can increase the effect of rectifying the cooling air and can prevent the cooling air caused to hit the non-paper feed area of the fixing film 13 from flowing to a paper feed area from the non-paper feed area, without increasing the number of the first rectification ribs 43L and the second rectification ribs 44L. Since the cooling air does not hardly flow from the non-paper feed area to the paper feed area, the temperature of the paper feed area of the fixing film 13 is hardly reduced compared with a temperature sufficient for fixing a toner image to a recording material.SELECTED DRAWING: Figure 9

Description

The present invention relates to a fixing device suitable for use in image forming apparatuses using electrophotographic technology, such as printers, copiers, facsimiles, and multi-function machines.

2. Description of the Related Art In an image forming apparatus, after a toner image is formed on a recording material such as paper, the toner image is fixed on the recording material by a fixing device. Various types of fixing devices have been proposed, but a film heating type fixing device is generally used. A film heating type fixing device has, for example, a fixing film (or fixing roller) that is heated by a heater or the like, and a pressure roller (or pressure belt) that contacts the fixing film to form a fixing nip portion. . The recording material on which the toner image is formed is subjected to heat and pressure when passing through the fixing nip portion, whereby the toner image is fixed to the recording material (Patent Document 1).

In recent years, in order to cope with a wider variety of media, a film heating type fixing device has been used which is compatible with a larger number of different sizes of recording materials. In this fixing device, there is a case where a large number of recording materials having a width smaller than the maximum width in the width direction (the direction intersecting the conveying direction of the recording material passing through the fixing nip portion) are continuously fixed. In such a case, a partial area (referred to as a non-passing area for convenience) is formed on both widthwise end portions of the fixing film, with which the recording material passing through the fixing nip portion does not come into contact. In this non-paper-passing area, since heat is less likely to be lost from the fixing film to the recording material, the heat is accumulated and the temperature rises (for convenience, this is referred to as a non-paper-passing area temperature rise). If the temperature of the non-paper-passing area becomes too high, toner adheres to the fixing film when fixing is performed on a recording material having a wider width, causing a decrease in image density (so-called hot offset). In addition, there is a risk that surrounding resin members may be melted or their deterioration may be accelerated.

Therefore, in order to suppress the temperature rise of the non-paper-passing portion of the fixing film, there is a device, such as the device described in Patent Document 1, in which air from a cooling fan is applied to the non-paper-passing region of the fixing film through a duct. Proposed. In the case of the apparatus described in Patent Document 1, by moving the shutter in the width direction to adjust the opening width of the air outlet of the duct, the non-passage is formed according to the width of the recording material passing through the fixing nip portion. The wind of the cooling fan can be efficiently applied to the paper area. Further, in order to cool the recording material after fixing the toner image, cooling air may be applied to the recording material that has passed through the fixing nip portion. In this case, the cooling air applied to the recording material is prevented from hitting the paper passing area of the fixing film.

Japanese Patent Application Laid-Open No. 2015-158600

However, when cooling air hits the non-paper-passing area of the fixing film, conventionally, the temperature of the paper-passing area of the fixing film sometimes becomes lower than the temperature sufficient to fix the toner image on the recording material.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of suppressing a decrease in the temperature of a fixing film passing area when cooling air hits the non-paper passing area of the fixing film.

A fixing device according to an embodiment of the present invention is a fixing device for fixing a toner image formed on a recording material to the recording material, comprising: a first rotating body; a heating means for heating the first rotating body; a fixing unit that forms a fixing nip portion that abuts on the outer peripheral surface of the first rotating body and nips and conveys the recording material while applying heat and pressure to fix the toner image; and a cooling unit. a cooling unit having a fan that generates wind; and a duct that blows out the cooling air generated by the fan from an air outlet toward a non-sheet-passing area of the first rotating body; and the first rotating body and the cooling unit. and a fixing cover member provided in the fixing unit so as to be spaced apart, and having a ventilation hole formed at a position facing the air outlet in the width direction intersecting the recording material conveying direction to take in and pass the cooling air blown from the air outlet. , wherein the outlet has a plurality of first regulating ribs formed substantially perpendicular to the width direction, and the ventilation hole includes the first regulating ribs and A plurality of second straightening ribs are formed so as to be substantially orthogonal to the width direction so as not to overlap each other.

A fixing device according to an embodiment of the present invention is a fixing device for fixing a toner image formed on a recording material to the recording material, comprising: a first rotating body; a heating means for heating the first rotating body; a fixing unit that forms a fixing nip portion that abuts on the outer peripheral surface of the first rotating body and applies heat and pressure to fix the toner image while nipping and conveying the recording material; a recording material cooling unit provided downstream of the fixing unit in the recording material conveying direction and cooling the recording material by blowing cooling air onto the recording material that has passed through the fixing nip portion; a fixing cover member having a shielding surface that shields the first rotating body from the cooling air of the unit, and the fixing cover member passes the recording material having the maximum width in the width direction intersecting the recording material conveying direction. Outside the region, an inner rib extending in the rotational direction along the outer peripheral surface of the first rotating body is provided, and the shielding surface is a protruding wall surface that protrudes outward from the inner rib in the width direction. It is characterized by having a part.

According to the present invention, when cooling air hits the non-paper-passing area of the first rotating body, it is possible to suppress the temperature drop in the paper-passing area of the fixing film with a simple configuration.

1 is a schematic diagram showing a suitable image forming apparatus using the fixing device of the present embodiment; FIG. FIG. 2 is a schematic diagram showing a fixing device according to the first embodiment; FIG. 4 is a diagram showing the arrangement of thermistors in the fixing unit; The perspective view which shows a cooling unit. FIG. 5 is a perspective view showing the cooling unit of FIG. 4 turned over; FIG. 3 is a perspective view showing a shutter unit; FIG. 3 is a perspective view showing the cooling unit with the shutter unit removed; FIG. 3 is a perspective view showing a fixing cover; Sectional drawing which shows a 1st straightening rib and a 2nd straightening rib. 7A and 7B are graphs showing the wind speed distribution of the cooling air on the surface of the fixing film, in (a) the case without the first straightening rib and the second straightening rib, (b) the case of the comparative example, and (c) the case of the present embodiment. FIG. 5 is a cross-sectional view showing the flow of cooling air in a comparative example; FIG. 8 is a top view showing a fixing cover according to the second embodiment; Sectional drawing which shows the flow of the cooling air in 2nd embodiment. Schematic diagram showing a fixing unit of a third embodiment. FIG. 5 is a schematic diagram showing the flow of cooling air in the third embodiment; FIG. 4 is a cross-sectional perspective view showing a case where the fixing cover in the closed position is cut along the conveying direction;

<First embodiment>
[Image forming apparatus]
The fixing device of this embodiment will be described. First, an image forming apparatus suitable for using the fixing device of this embodiment will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 1 is an electrophotographic tandem full-color printer. The image forming apparatus 100 has image forming units PY, PM, PC, and PK that form yellow, magenta, cyan, and black toner images, respectively. The image forming apparatus 100 prints a toner image on a recording material S according to an image signal from an external device such as a document reading device (not shown) connected to the apparatus main body or a personal computer communicably connected to the apparatus main body. to form. Examples of the recording material S include sheet materials such as paper, plastic film, and cloth.

As shown in FIG. 1, the image forming units PY, PM, PC, and PK are arranged side by side along the moving direction of the intermediate transfer belt 8 (arrow R2 direction) in the apparatus main body. The intermediate transfer belt 8 is stretched between the drive roller 9 and the inner secondary transfer roller 66, and is moved by the drive roller 9 in the movement direction (arrow R2 direction). The intermediate transfer belt 8 carries and conveys the toner images primarily transferred from the photosensitive drums 1Y, 1M, 1C, and 1K.

A secondary transfer outer roller 67 is disposed at a position opposed to a secondary transfer inner roller 66 on which the intermediate transfer belt 8 is stretched, with the intermediate transfer belt 8 interposed therebetween. A secondary transfer nip portion T2 is formed for transferring the image. A fixing device 200 is arranged downstream of the pair of secondary transfer inner roller 66 and secondary transfer outer roller 67 in the recording material conveying direction. In this embodiment, the image forming units PY to PK, the exposure device 3, the intermediate transfer belt 8, the drive roller 9, the inner secondary transfer roller 66, and the outer secondary transfer roller 67 form the toner image on the recording material S. It constitutes an image forming unit 150 capable of forming.

A cassette 62 in which the recording material S is accommodated is arranged in the lower portion of the image forming apparatus 100 . The recording materials S contained in the cassette 62 are supplied one by one from the cassette 62 to the transport path 64 by the transport roller 63 in accordance with the image forming timing. Alternatively, the recording materials S stacked on the manual feed tray 61 are fed to the conveying path 64 one by one. The recording material S is conveyed to a registration roller 65 arranged in the middle of the conveying path 64, subjected to skew correction and timing correction by the registration roller 65, and sent to the secondary transfer nip portion T2. The registration roller 65 is rotated in synchronism with the toner image formed on the intermediate transfer belt 8 .

The four image forming units PY, PM, PC, and PK provided in the image forming apparatus 100 have substantially the same configuration except that the toner colors used in the developing devices 4Y, 4M, 4C, and 4K are different. Therefore, here, the yellow image forming portion PY will be described as a representative, and description of the other image forming portions PM, PC, and PK will be omitted. A photosensitive drum 1Y is disposed in the image forming portion PY. The photosensitive drum 1Y is rotationally driven in the direction of arrow R1. A charging device 2Y, a developing device 4Y, and a primary transfer roller 5Y are arranged around the photosensitive drum 1Y.

When the image forming operation is started, first, the surface of the rotating photosensitive drum 1Y is uniformly charged by the charging device 2Y. Next, the photosensitive drum 1Y is scanned and exposed by a laser beam emitted from an exposure device 3 (for example, a laser scanner) shared by the image forming units PY, PM, PC, and PK. As a result, an electrostatic latent image corresponding to the image signal is formed on the photosensitive drum 1Y. The electrostatic latent image formed on the photosensitive drum 1Y is developed with toner (developer) housed in the developing device 4Y to form a toner image.

The toner image formed on the photosensitive drum 1Y is primarily transferred onto the intermediate transfer belt 8 at a primary transfer portion configured between the intermediate transfer belt 8 and a primary transfer roller 5Y arranged with the intermediate transfer belt 8 interposed therebetween. At this time, a primary transfer voltage is applied to the primary transfer roller 5Y.

By sequentially performing the operations described above in the yellow, magenta, cyan, and black image forming portions PY to PK, toner images of four colors can be formed on the intermediate transfer belt 8 . Depending on the case, it is possible to form a toner image of a single color or to form a toner image of a desired color by appropriately superimposing some of the four colors. After that, the recording material S is conveyed sheet by sheet from the cassette 62 or the manual feed tray 61 toward the secondary transfer nip portion T2 in synchronization with the formation timing of the toner image. By applying a secondary transfer voltage to the secondary transfer outer roller 67, the toner image formed on the intermediate transfer belt 8 is transferred to the recording material S when the recording material S passes through the secondary transfer nip portion T2. is secondarily transcribed to A small amount of transfer residual toner remaining on the intermediate transfer belt 8 after the recording material S has passed through the secondary transfer nip portion T2 is removed from the intermediate transfer belt 8 by the belt cleaner 110 .

The recording material S onto which the toner image has been transferred from the intermediate transfer belt 8 is conveyed toward the fixing device 200 . In the fixing device 200, the toner image is fixed on the recording material S by applying heat and pressure to the recording material S while nipping and conveying the recording material S. As shown in FIG. Details of the fixing device 200 of the present embodiment will be described later (see FIGS. 2 to 11 described later).

The recording material S on which the toner image is thus fixed is discharged onto the discharge tray 601 by the discharge roller 69 . The image forming apparatus 100 includes a control section 300 for performing various controls such as the image forming operation described above. The series of image forming operations in the image forming apparatus 100 are controlled by the control unit 300 in accordance with an input signal from an operation unit (not shown) provided in the apparatus main body or an input signal from an external device via a communication network. .

[Fixing device]
Next, the fixing device 200 of this embodiment will be described with reference to FIGS. 2 to 11. FIG. Hereinafter, in the present specification, the width direction (longitudinal direction) is the direction intersecting the conveying direction of the recording material S in the fixing nip portion N described later, in other words, the rotation axis direction of the pressure roller 20 . Further, when the fixing device 200 is viewed from the conveying direction of the recording material S (direction of arrow Y), it is called "front", the left side when viewed from the front is called "left", and the right side when viewed from the front is called "right". 2 shows the fixing device 200 viewed from the right.

The fixing device 200 of this embodiment is a film heating type fixing device, and includes a fixing unit 210 and a cooling unit 250 as shown in FIG. The fixing unit 210 mainly has the film unit 10 and the pressure roller 20 . 2, the illustration of a fixing cover 45 (see FIGS. 8 and 9), which will be described later, is omitted in order to facilitate understanding of the description.

[Pressure roller]
The pressure roller 20 as a second rotating body is rotatably supported by the housing 25 (side plates, etc.) of the fixing unit 210 at both ends in the width direction. The pressure roller 20 has an elastic solid rubber layer, an elastic sponge rubber layer, or an elastic cellular rubber layer on the outer periphery of a metal core 21 made of metal such as SUS (stainless steel) or SUM (sulfur and sulfur composite free-cutting steel). It is an elastic roller formed with an elastic layer 22 such as . For example, the elastic solid rubber layer is made of heat-resistant rubber such as silicone rubber or fluororubber, and the elastic sponge rubber layer is made by foaming silicone rubber in order to provide a better heat insulating effect. The elastic cellular rubber layer is obtained by dispersing hollow fillers (such as microballoons) in the silicone rubber layer to enhance the heat insulating effect. A release layer such as perfluoroalkoxy resin (PFA) or polytetrafluoroethylene resin (PTFE) may be further formed on the elastic layer 22 .

The pressure roller 20 contacts the fixing film 13 of the film unit 10 to form a fixing nip portion N. As shown in FIG. As the pressure roller 20 is rotated in the direction of rotation (the direction of arrow A in FIG. 2) by a motor, driving gear, etc. (not shown), the frictional force generated in the fixing nip portion N causes the pressure roller 20 to rotate. A force is transmitted to the fusing film 13 . Thus, the endless fixing film 13 is rotationally driven by the pressure roller 20 (so-called pressure roller driving method). The recording material S on which the toner image is formed is nipped and conveyed while being pressed by the fixing nip portion N formed by the rotating pressure roller 20 and the fixing film 13 .

In the present embodiment, when the fixing film 13 is driven to rotate as the pressure roller 20 is rotationally driven, the fixing film 13 is heated by the heater 11, which will be described later. Then, the recording material S on which the toner image is formed by the image forming unit 150 (see FIG. 1) is conveyed to the fixing nip portion N while the temperature of the heater 11 is adjusted to a predetermined target temperature. When the recording material S is nipped and conveyed at the fixing nip portion N, heat is applied to the recording material S via the fixing film 13 heated by the heater 11 , and the toner image is fixed on the recording material S.

[Film unit]
The film unit 10 will be explained. The film unit 10 is provided movably toward the pressure roller 20 side. The film unit 10 includes a fixing film 13, a stay 14 and a heater holder 12 non-rotatably arranged inside the fixing film 13, a heater 11, thermistors (18, 19a, 19b), a fixing cover 45 described later, and the like.

[Fixing film]
The fixing film 13 as the first rotating body is a thin heat-resistant film formed in an endless (cylindrical) shape and having flexibility. The fixing film 13 is made of a heat-resistant resin such as polyimide, polyamide-imide, or PEEK (polyetheretherketone), or a metal or alloy having heat resistance and high thermal conductivity such as SUS, Al, Ni, Cu, or Zn. formed. In the case of a base material made of resin, high heat conductive powder such as BN, alumina, Al, etc. may be mixed in order to improve the heat conductivity. In order to ensure the strength and durability of the fixing film 13, the total thickness must be 100 μm or more. In order to prevent offset and ensure the separability of the recording material S, the surface layer is mixed with heat-resistant resins such as fluororesins such as PTFE, PFA, FEP, ETFE, CTFE, and PVDF, and silicone resins, which have excellent releasability. or coated alone to form a release layer. In this embodiment, the fixing film 13 whose surface layer is made of a material containing at least PTFE and PFA and whose total thickness is "100 μm or more and 200 μm or less" is used.

Here, PTFE is "polytetrafluoroethylene", PFA is "tetrafluoroethylene perfluoroalkyl vinyl ether copolymer", and FEP is "tetrafluoroethylene hexafluoropropylene copolymer". ETFE is "ethylene tetrafluoroethylene copolymer", CTFE is "polychlorotrifluoroethylene", and PVDF is "polyvinylidene fluoride".

As a method of forming the release layer by coating, there are a method of etching the outer peripheral surface of the fixing film 13 and then dipping, a method of applying a powder spray, and the like. Further, a method of covering the surface of the fixing film 13 with a tube-shaped resin, or a method of applying a primer layer as an adhesive to the outer peripheral surface of the fixing film 13 that has been blasted to cover the release layer, and the like. There is

The fixing film 13 is detachably attached to the heater holder 12, and supported by flanges 16 arranged at both ends in the width direction of the fixing film 13 so as to be rotatable and restricted in movement in the width direction. Although not shown, the flange 16 includes a cylindrical portion that is fitted in the widthwise end portion of the fixing film 13 to rotatably support the fixing film 13 and a contact that can contact the widthwise end edge of the fixing film 13 . and a contact portion. The cylindrical portion guides the rotation of the fixing film 13 while holding the ends of the fixing film 13 in the width direction from the inside in a cylindrical state. When the fixing film 13 shifts in the width direction, the abutting portion receives the width direction end portion of the fixing film 13 and restricts the width direction movement of the fixing film 13 . By attaching the heater holder 12 and the stay 14 to the flange 16 , the heater holder 12 and the stay 14 are arranged inside the fixing film 13 in a non-rotating manner.

[stay]
The stay 14 is, for example, a metal rigid member (sheet metal) extending in the width direction along the fixing film 13 and has a substantially U-shaped cross section with an opening on the heater holder 12 side. The above-described flanges 16 are fixed to both ends of the stay 14 in the width direction. These flanges 16 are movably held by a housing 25 (side plate, etc.) of the fixing unit 210, and are pressed with a predetermined pressing force (for example, 90 to 320 N) by a pressure arm 23 biased by a pressure spring 15. It is pressed towards roller 20 . As a result, pressure is applied from the flange 16 to the fixing film 13 via the stay 14 and the heater holder 12, and the fixing film 13 and the pressure roller 20 are pressed against each other with a predetermined pressure. A fixing nip portion N is formed between the fixing film 13 and the pressure roller 20 by pressing the fixing film 13 and the pressure roller 20 together. At this time, the stay 14 can prevent the film unit 10 from bending or twisting due to the pressure acting between the film unit 10 and the pressure roller 20 .

[Heater holder]
The heater holder 12 is made of resin such as liquid crystal polymer, phenolic resin, PPS, PEEK, and the like, and holds the heater 11 as a heating member and guides the fixing film 13 . . The lower the thermal conductivity, the less the heat from the heater 11 is absorbed and the more efficiently the heat can be transferred to the fixing film 13. Therefore, fillers such as glass balloons and silica balloons are included in the resin layer. good too. In the heater holder 12, on the surface opposite to the stay 14 side (fixing nip portion N side), a fitting groove capable of fitting and holding the heater 11 is formed in a shape extending along the width direction. there is The heater 11 held by the heater holder 12 contacts the inner peripheral surface of the fixing film 13 and heats the rotating fixing film 13 . As a result, when the recording material S passes through the fixing nip portion N, the heat of the heater 11 is conducted to the recording material S through the fixing film 13, and the toner image is melted by the heat and fixed on the recording material S. be. The inner peripheral surface of the fixing film 13 is coated with a lubricant such as fluorine-based or silicone-based heat-resistant grease. This is because the frictional resistance between the inner peripheral surface of the fixing film 13 and the heater holder 12 is kept low and the rotation of the fixing film 13 is not hindered.

[heater]
A heater 11 as heating means is, for example, a ceramic heater, and a heating element (not shown) is formed to have a length corresponding to or longer than the recording material S having the maximum width. A polyimide layer, for example, is formed on one side of the heater 11 that contacts the inner peripheral surface of the fixing film 13 . By forming the polyimide layer on the heating heater 11, the frictional resistance between the fixing film 13 and the heating heater 11 can be reduced, thereby reducing the driving torque for rotating the fixing film 13 and the abrasion of the fixing film 13 due to rubbing. can be reduced.

The temperature control of the heater 11 is performed by the controller 300 (see FIG. 1) based on detection signals from the thermistors 18, 19a and 19b. The control unit 300 controls the heater 11 as well as the entire image forming apparatus 100 . The control unit 300 has a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU controls each section by executing various programs such as an image forming job stored in the ROM. The RAM stores work data and input data, and the CPU performs control by referring to the data stored in the RAM when executing various programs.

In the case of this embodiment, the control unit 300 adjusts the voltage applied by a power source (not shown) based on the detection signals of the thermistors 18, 19a, and 19b so that the temperature of the heater 11 reaches the target temperature (for example, 200 ℃) can be controlled. The first thermistor 18 is provided on the heater holder 12 via a biasing means (not shown) such as a spring so as to contact the back surface of the heater 11 opposite to the fixing film 13 with a predetermined pressure. The temperature of the heater 11 is detected. One thermistor 18 is arranged in the central portion of the heater 11 in the width direction, and detects the temperature of the central portion of the heater 11 . The number of thermistors 18 is not limited to one, and a plurality of thermistors may be arranged along the width direction of the fixing film 13 .

On the other hand, as shown in FIG. 3, the second thermistors 19a and 19b are arranged at the central portion and one end portion of the fixing film 13 in the width direction. The temperature of the fixing film 13 is detected by contact. The thermistor 19 a detects the temperature of the fixing film 13 by contacting the inner peripheral surface of the fixing film 13 at a position substantially corresponding to the central reference line O downstream of the fixing nip portion N of the fixing film 13 in the rotation direction. The thermistor 19b is located downstream of the fixing nip portion N of the fixing film 13 in the film rotation direction and close to the end portion of the maximum paper passing area (Wmax) described later (position serving as a non-paper passing area). The temperature of the fixing film 13 is detected by contacting the inner peripheral surface of the fixing film 13 .

Here, in the fixing device 200 of the present embodiment, the recording material S is conveyed by so-called "center reference conveyance". The center reference transport means that when transporting recording materials S having different sizes in the width direction, the recording materials S are directed toward the fixing nip portion N so that the centers of the respective recording materials S in the width direction are substantially aligned. It is a method of transportation. In FIG. 3, a center reference line O indicates a position where the center of the recording material S in the width direction substantially coincides. Further, in FIG. 3, "Wmax" indicates the maximum width (passing area width) of the sheet passing area of the recording material S, and is, for example, "330 mm". On the other hand, "Wmin" indicates the minimum width of the sheet passing area of the recording material S, and is, for example, "100 mm". When the recording material S having a width smaller than the maximum width is conveyed by the "center reference conveyance", the distance from the end of the maximum paper passing area (Wmax) to the end of the recording material S on both end sides of the fixing film 13 is , a partial area (non-passage area) that does not contact the recording material S when passing through the fixing nip portion N is generated. That is, the width of the non-sheet-passing area changes according to the width of the recording material S. FIG.

Therefore, the thermistor 19a is provided so as to be capable of detecting the temperature of the minimum sheet passage area (Wmin) through which all the conveyable recording materials S pass regardless of the width. On the other hand, the thermistor 19b is provided so as to be able to detect the temperature of the non-sheet passing area generated when the recording material S having a width smaller than the maximum width passes. The effective heat generation area of the heating element (not shown) in the heater 11 is set equal to or larger than the maximum paper passing area (Wmax).

[Cooling unit]
Next, the cooling unit 250 will be described using FIGS. 4 to 7 while referring to FIG. The cooling unit 250 is provided adjacent to the fixing unit 210 in order to suppress the temperature rise in the non-sheet passing portion of the fixing film 13 that occurs when the recording material S having a width smaller than the recording material S having the maximum width is continuously conveyed. It is The cooling unit 250 is arranged so that its outlets 31L and 31R (see FIG. 7) approximately match the ventilation holes 38L and 38R (see FIG. 8) formed in the partition wall 45U (top plate) of the fixing cover 45, respectively. is provided.

The cooling unit 250 includes a plurality of ducts (32L, 32R) having outlets (31L, 31R) and a plurality of cooling units that generate cooling air to be blown from the outlets (31L, 31R) through these ducts (32L, 32R). It has fans (33L, 33R). Specifically, as shown in FIG. 7, the cooling unit 250 has a first duct 32L having an air outlet 31L for cooling the non-sheet-passing area that may occur on the left end side of the fixing film 13. ing. In addition, the cooling unit 250 has a second duct 32R formed with an air outlet 31R in order to cool a non-sheet-passing area that may occur on the right end side of the fixing film 13. As shown in FIG.

As shown in FIG. 5, the first duct 32L is provided with a first cooling fan 33L for blowing cooling air from the outlet 31L, and the second duct 32R is provided with cooling air from the outlet 31R. A second cooling fan 33R is provided for this purpose. It is preferable that the first cooling fan 33L and the second cooling fan 33R are the same from the viewpoint of easiness of fan replacement and cost reduction.

[Shutter unit]
4, the cooling unit 250 has a shutter unit 340 capable of adjusting the opening width of the outlet 31L of the first duct 32L and the opening width of the outlet 31R of the second duct 32R. . The shutter unit 340 includes a shutter 36L capable of opening and closing the outlet 31L, a shutter 36R capable of opening and closing the outlet 31R, a rack and pinion mechanism 600 (see FIG. 6) for moving these shutters 36L and 36R in the width direction, It has a shutter motor M (see FIG. 5).

As shown in FIG. 6, the shutters 36L and 36R are configured to slide reciprocally in the width direction (direction of arrow X) by a rack and pinion mechanism 600 using a rack and pinion. Specifically, in the shutters 36L and 36R, when the drive pinion gear 41 that is drivingly connected to the shutter motor M (see FIG. 5) rotates, the racks 42L and 42R that are engaged with the drive pinion gear 41 move in opposite directions. . Then, the shutters 36L and 36R configured to move together with the racks 42L and 42R move in opposite directions. In this manner, the shutters 36L and 36R are interlocked to open and close the outlets 31L and 31R in accordance with the forward and reverse rotation of the drive pinion gear 41 by the shutter motor M, thereby allowing the opening width to be adjusted. In the case of this embodiment, the shutter 36R is provided with a plurality of sensor flags 39 at predetermined positions corresponding to recording materials S having different widths.

The opening/closing control of the shutters 36L and 36R will be briefly described. As shown in FIGS. 2 and 4, the cooling unit 250 is provided with a photosensor 40 for detecting the sensor flag 39 described above. A detection signal from the photosensor 40 is input to the control unit 300 (see FIG. 1). When the control unit 300 acquires information about the width of the recording material S from an operation unit (not shown) or an external device, the shutter motor M continues until the photosensor 40 detects the sensor flag 39 corresponding to the width of the recording material S. forward and reverse to move the shutters 36L and 36R. In this way, the shutters 36L and 36R are moved to positions corresponding to the width of the conveyed recording material S with respect to the outlets 31L and 31R, respectively. Thereby, the opening widths of the outlets 31L and 31R are adjusted.

As described above, the range of the cooling air blown from the first duct 32L is restricted according to the opening width of the outlet 31L being adjusted by the shutter 36L. The range of the cooling air blown from the second duct 32R is restricted according to the opening width of the outlet 31R being adjusted by the shutter 36R. In this manner, the shutters 36L and 36R adjust the opening widths of the outlets 31L and 31R to the optimum opening width according to the width of the recording material S, and the temperature rise range of the non-sheet-passing portion varies according to the width of the recording material S. The cooling air can be efficiently applied to the (non-paper-passing area). The end of the shutter 36L (36R) on the outlet side is located outside the paper passing area of the fixing film 13 in a state where the opening width of the outlet 31L (31R) is adjusted.

The control of the cooling fans 33L and 33R will be briefly described. The control unit 300 starts operating the cooling fans 33L and 33R when the temperature of the fixing film 13 detected by the thermistor 19b (see FIG. 3) exceeds a predetermined upper temperature limit (for example, 200 degrees). The cooling air from the cooling fans 33L and 33R passes through the first duct 32L and the second duct 32R, respectively, and passes through the air outlets 31L and 31R to reach a part of the fixing film 13 in the width direction. In the form, it is sprayed on predetermined areas on both end sides. In this way, by blowing cooling air from the cooling fans 33L and 33R, it is possible to suppress the temperature rise of the non-sheet-passing portions. The control unit 300 stops the cooling fans 33L and 33R when the temperature of the fixing film 13 detected by the thermistor 19b drops below a predetermined lower limit temperature (for example, 190 degrees). Note that the upper limit temperature and the lower limit temperature may differ according to the width of the recording material S. Further, while the cooling fans 33L and 33R are operating, the rotation speed of the fan blades may be changed according to the temperature detected by the thermistor 19b.

[Fusing cover]
Next, the fixing cover 45 will be described using FIG. 8 while referring to FIGS. 2 and 7. FIG. In the film unit 10, a fixing cover 45 as a fixing cover member is provided so as to be openable and closable. In this embodiment, the fixing cover 45 is attached to the housing (for example, the frame) of the film unit 10 via the supporting portions 45L and 45R shown in FIG. 8 so as to separate the fixing film 13 and the cooling unit 250. It is rotatably supported. When replacing the fixing film 13, the operator can replace the fixing film 13 by moving the fixing cover 45 from the closed position to the open position. After the replacement, the operator returns the fixing cover 45 to the closed position to separate the fixing film 13 and the cooling unit 250 .

As shown in FIG. 8, the partition wall 45U of the fixing cover 45 substantially faces the outlets 31L and 31R (see FIG. 7) of the cooling fans 33L and 33R when the fixing cover 45 is in the closed position. Ventilation holes 38L and 38R are formed at the positions. These ventilation holes 38L and 38R are located symmetrically on the left and right sides of the above-described central reference line O, more specifically, on the left and right edge sides of the fixing film 13 when the recording material S having the minimum width is conveyed. It is formed to have a width that covers at least a possible non-paper-passing area. The width dimension (length dimension) of the ventilation holes 38L and 38R is, for example, "115 mm {(330 mm-100 mm)/2}".

As described above, the cooling air from the cooling fans 33L and 33R passes through the ventilation holes 38L and 38R of the fixing cover 45 from the air outlets 31L and 31R of the first duct 32L and the second duct 32R. blown out into the area. However, if rectifying ribs for rectifying the cooling air are not formed in the air outlets 31L, 31R and the ventilation holes 38L, 38R, the cooling air tends to flow into the paper passing area of the fixing film 13, and the temperature of the paper passing area rises. It can be below the temperature sufficient to fix the toner image. In addition, the air velocity distribution of the cooling air hitting the fixing film 13 is greatly different between the left end portion side and the right end portion side of the fixing film 13, which may cause temperature unevenness. This is because the cooling air is dispersed and spreads before hitting the fixing film 13 through the outlets 31L and 31R and the ventilation holes 38L and 38R. In particular, when the cooling fans 33L and 33R are the same, and the left and right fan blades rotate in the same direction, the cooling air velocity distribution tends to differ between the left end portion and the right end portion of the fixing film 13. . The above-described temperature drop and temperature unevenness are not preferable because they make it difficult for the toner image to be properly fixed on the recording material S.

Therefore, in the present embodiment, in order to suppress the lateral difference in the wind speed distribution of the cooling air as described above, a plurality of air outlets 31L and 31R of the cooling unit 250 and the ventilation holes 38L and 38R of the fixing cover 45 are respectively provided with a plurality of air outlets. Straightening ribs are formed. The rectifying ribs formed in the outlets 31L and 31R and the ventilation holes 38L and 38R will be described below with reference to FIGS. 7 to 11. FIG. The configuration of the rectifying ribs is the same for the left and right air outlets 31L and 31R, and the configuration of the rectifying ribs is the same for the left and right ventilation holes 38L and 38R. The rectifying ribs formed will be described as an example.

First, as shown in FIG. 7, the outlet 31L of the cooling unit 250 is formed with a plurality of first straightening ribs 43L. The first straightening rib 43L is formed substantially orthogonal to the width direction. Here, being substantially perpendicular to the width direction means that the angle (acute angle) formed by the first straightening rib 43L and the imaginary straight line extending in the width direction is 85° or more and 90° or less. In the case of this embodiment, the plurality of first straightening ribs 43L are arranged in the width direction at substantially equal intervals. These first rectifying ribs 43L extend toward the fixing film 13 side over the entire area inside the air outlet 31L, as shown in FIG. In addition, auxiliary ribs 43A may extend along the width direction of the outlet 31L so as to cross the plurality of first rectifying ribs 43L. A plurality of auxiliary ribs 43A may be provided.

On the other hand, as shown in FIG. 8, a plurality of second rectifying ribs 44L are formed in the ventilation holes 38L of the fixing cover 45. As shown in FIG. The second straightening rib 44L is formed substantially perpendicular to the width direction. In the case of this embodiment, the plurality of second straightening ribs 44L are arranged in the same direction as the first straightening ribs 43L at substantially equal intervals in the width direction. The interval between the second straightening ribs 44L and the interval between the first straightening ribs 43L may be substantially the same. These second regulating ribs 44L extend toward the fixing film 13 over the entire area inside the ventilation holes 38L, as shown in FIG. Also in the ventilation holes 38L, the auxiliary ribs 44A may extend along the width direction so as to cross the plurality of second straightening ribs 44L. A plurality of auxiliary ribs 44A may be provided.

In this embodiment, as shown in FIG. 9, the second straightening rib 44L is formed between the first straightening rib 43L and the first straightening rib 43L in the width direction. Specifically, each of the second rectifying ribs 44L in the ventilation hole 38L is formed so as not to overlap with the first rectifying rib 43L formed in the outlet 31L when viewing the ventilation hole 38L from the outlet 31L. In the example shown in FIG. 9, the same number of first straightening ribs 43L and second straightening ribs 44L are formed. Further, each of the second straightening ribs 44L is formed closer to the center than the first straightening ribs 43L.

10(a) to 10(c) show graphs of experimental results obtained by actually applying cooling air to the fixing film 13 and measuring the air velocity of the cooling air on the surface of the fixing film. 10(a) shows the case where the first straightening rib 43L and the second straightening rib 44L are not formed, FIG. 10(b) shows the comparative example shown in FIG. 11, and FIG. 10(c) shows the case shown in FIG. It is each experimental result in the case of this embodiment. The horizontal axis represents the position (m) in the width direction of the fixing film 13, and the vertical axis represents the wind speed (m/s) on the surface of the fixing film.

In order to make it easier to understand the left-right difference in the wind speed distribution on the surface of the fixing film, the wind speed distribution graph (solid line) is inverted with respect to the central reference line O (see FIG. 3), and a dotted line is added. . Since the solid line and the dotted line wind speed distribution graphs are merely reversed and superimposed, if the amount of deviation between the two wind speed distribution graphs is small, it means that the left and right wind speeds are less likely to differ.

The comparative example shown in FIG. 11 is the same as this embodiment in that the first rectifying rib 43L and the second rectifying rib 44L are formed substantially perpendicular to the width direction, and the airflow from the outlet 31L is the same. It differs in that the first straightening rib 43L and the second straightening rib 44L overlap when looking at the hole 38L.

Comparing FIG. 10(a) and FIG. 10(b), it can be seen that the air velocity is lower when the first straightening rib 43L and the second straightening rib 44L are formed inside the end of the paper passing area. I understand. Also, it can be seen that the difference in wind speed between the left and right sides (deviation between the solid line and the dotted line in the graph) is reduced when the first straightening rib 43L and the second straightening rib 44L are formed. Comparing the average wind speed values of the fixing film surfaces on the left and right sides from the center of the paper-passing area, it is 0.611 m/s when the straightening ribs (43L, 44L) are not formed, whereas it is 0.611 m/s. was "0.417 m/s".

Comparing FIG. 10(b) and FIG. 10(c), it can be seen that the wind speed is lower inside the edge of the paper passing area in this embodiment than in the comparative example. That is, in this embodiment, it is more difficult for the cooling air to flow from the non-sheet-passing area to the sheet-passing area than in the comparative example. This is because, as described above, in the present embodiment, the first straightening rib 43L and the second straightening rib 44L are formed so as not to overlap each other, so that the cooling air straightening effect can be enhanced with a small number of ribs. is.

For example, the cooling air rectifying effect can be enhanced by simply increasing the number of the first rectifying ribs 43L and forming the first rectifying ribs 43L longer toward the fixing film 13 side. It was difficult to do so. Therefore, it is conceivable to secure the length by forming the second straightening rib 44L at the extension of the first straightening rib 43L (that is, so as to overlap). However, even if this is done, unless the number of the first rectifying ribs 43L and the second rectifying ribs 44L is increased, the cooling air flowing from the non-sheet-passing area to the sheet-passing area is reduced to the extent that the temperature drop in the sheet-passing area is suppressed. was difficult. On the other hand, in the present embodiment, without increasing the number of the first rectifying ribs 43L and the second rectifying ribs 44L, the rectifying effect of the cooling air is enhanced to make it difficult for the cooling air to flow from the non-sheet-passing area to the sheet-passing area. be able to. Therefore, the temperature of the paper passing area of the fixing film 13 is unlikely to be lower than the temperature sufficient to fix the toner image on the recording material S.

Moreover, even when the first straightening rib 43L and the second straightening rib 44L are formed, it can be seen that the left and right wind speed difference is further reduced in the present embodiment compared to the comparative example. Comparing the average wind speed values on the fixing film surfaces on the left and right sides from the center of the paper-passing area, the comparative example is "0.417 m/s" as described above, while the present embodiment is "0.152 m/s." "Met.

That is, in the case of the comparative example shown in FIG. 11, the cooling air emitted from the cooling fan 33L tends to spread in a substantially oblique direction according to the rotation direction of the fan blades. At this time, if ribs orthogonal to the width direction are formed in the blow-out port 31L of the first duct 32L and the ventilation hole 38L of the fixing cover 45, the cooling air that is about to spread in a substantially oblique It is rectified to face perpendicular to the direction. Therefore, even in the case of the comparative example shown in FIG. 11, as compared with the case where the first straightening rib 43L and the second straightening rib 44L are not formed, as shown in the above-described experimental results, the cooling effect on the surface of the fixing film 13 is higher. The lateral difference of the wind can be reduced. However, when the numbers of the first straightening ribs 43L and the second straightening ribs 44L are small, as in the comparative example, the temperature of the paper passing area is lower than the temperature sufficient to fix the toner image, or the temperature unevenness occurs. was happening.

In contrast to such a comparative example, in the present embodiment in which the first straightening rib 43L and the second straightening rib 44L are formed at different positions in the width direction as described above, the second straightening rib 44L is positioned relative to the first straightening rib 43L. The left-right difference of the cooling air can be further reduced without increasing the number of . As shown in FIG. 9, in the case of the present embodiment, the cooling air generated by the cooling fan 33L is rectified by the first rectifying ribs 43L of the outlet 31L in the first duct 32L so as to prevent non-uniform diffusion, while being rectified by the fixing cover. 45 to the vent hole 38L. When the cooling air flows into the ventilation holes 38L from the air outlet 31L, the cooling air flows toward the fixing film 13 while being rectified by the second rectifying ribs 44L of the ventilation holes 38L so as to prevent uneven diffusion. As a result, compared to the comparative example in which the positions of the first rectifying rib 43L and the second rectifying rib 44L are aligned, the lateral difference of the cooling air hitting the fixing film 13 can be reduced as shown in the above experimental results.

As described above, in the present embodiment, the fixing cover 45 is formed with the second rectifying ribs 44L and 44R formed in the ventilation holes 38L and 38R so as not to overlap the first rectifying ribs 43L and 43R formed in the outlets 31L and 31R. is interposed to apply cooling air to the non-paper-passing area of the fixing film 13 . This makes it difficult for the cooling air applied to the non-paper passing area of the fixing film 13 to flow from the non-paper passing area to the paper passing area. In addition, the lateral difference of the cooling air applied to the fixing film 13 can be reduced. As described above, according to the present embodiment, it is possible to suppress the temperature drop in the paper-passing area of the fixing film 13 with a simple configuration. Especially when the cooling fans 33L and 33R are the same fan, it is advantageous to employ this embodiment.

<Second embodiment>
In the above-described first embodiment, an example is shown in which a plurality of second straightening ribs 44L, 44R are formed in the ventilation holes 38L, 38R of the fixing cover 45 at substantially equal intervals in the width direction, but the present invention is not limited to this. . The plurality of second straightening ribs 44L, 44R may not be formed at substantially equal intervals in the width direction. The fixing cover 45 on which the second straightening ribs 44L and 44R are formed in this manner will be described with reference to FIGS. 12 and 13. FIG. In addition, the second straightening rib 44L formed in the ventilation hole 38L will be described as an example here as well. In addition, FIG. 13 shows an example of the flow of cooling air (air flow) when A4R paper as the recording material S is conveyed.

As shown in FIG. 12, in the fixing cover 45 of the second embodiment, a plurality of second straightening ribs 44L are formed at positions corresponding to the width of the recording material S in the ventilation holes 38L. In the case of this embodiment, a plurality of second straightening ribs 44L are formed at positions corresponding to the widths of the recording materials S of A4, B5, A4R, and B5R sheets. Here, the width of the sheet passage area of the recording material S is 297 mm for A4 paper, 257 mm for B5 paper, 210 mm for A4R paper, and 182 mm for B5R paper.

The plurality of second straightening ribs 44L are formed in the vicinity of the respective ends of the recording material S passing through the fixing nip portion N on the fixing film 13 and at opposing positions outside the paper passing area. That is, the second straightening rib 44L-1 is formed near the edge of the B5R paper, and the second straightening rib 44L-2 is formed near the edge of the A4R paper. Also, a second straightening rib 44L-3 is formed near the edge of B5 paper, and a second straightening rib 44L-4 is formed near the edge of A4 paper. Note that the position near the end of the recording material S and outside the paper-passing area referred to here means a position separated by "0.5 to 1.0 mm" from the end of each of the recording materials S having different widths. It refers to the area outside the paper area.

In the above range, for example, as shown in FIG. 13, the cooling air blown from the ventilation hole 38L and hitting the fixing film 13 does not go around the second straightening rib 44L-2 and reach the paper passing area of the fixing film 13. Range. Then, the area of the fixing film 13 corresponding to the space between the second rectifying rib 44L-2 and the edge V of the A4R paper is cooled by the cooling air that has flowed around the second rectifying rib 44L-2 to cool the non-paper-passing area. It is a range that does not raise the temperature. In this way, the plurality of second straightening ribs 44L are formed near the ends of the recording material S having different widths, so that the cooling air flows along the second straightening ribs 44L, and the fixing film is moved by the cooling air. Only the non-paper-passing areas are cooled without cooling the paper-passing areas of 13 .

<Third embodiment>
Next, the fixing unit of the third embodiment will be explained using FIGS. 14 to 16. FIG. 15 and 16, illustration of the partition wall 45U of the fixing cover 45 is omitted in order to facilitate understanding of the explanation.

As shown in FIG. 14, in this embodiment, a recording material cooling unit 500 is provided downstream of the fixing unit 210A. The recording material cooling unit 500 has a discharge unit 55 , a cooling duct 54 and a recording material cooling fan 53 . The discharge unit 55 conveys the recording material S on which the toner image has been fixed after passing through the fixing nip portion N formed by the fixing film 13 and the pressure roller 20 toward the discharge roller 69 (see FIG. 1). The recording material cooling fan 53 is driven by a motor (not shown) to draw outside air into the fixing unit 210A as cooling air. The cooling duct 54 guides the cooling air from the recording material cooling fan 53 toward the discharge unit 55 . The recording material S that has passed through the fixing nip portion N is cooled by cooling air from the recording material cooling fan 53 while passing through the discharge unit 55 . As a result, the temperature of the recording material S heated at the fixing nip portion N is lowered after the toner image is fixed, so that the toner image is fixed on the recording material S more reliably.

As described above, when the cooling air from the recording material cooling fan 53 hits the recording material S passing through the ejection unit 55 to cool the recording material S, part of the cooling air from the recording material cooling fan 53 is directed toward the fixing film 13 side. can flow. If the cooling air hits the paper-passing area of the fixing film 13, the temperature of the paper-passing area may drop below the temperature sufficient to fix the toner image. Therefore, the fixing cover 45 is provided with a shielding surface 45a on the ejection unit 55 side so that even if the cooling air from the recording material cooling fan 53 flows toward the fixing film 13, it does not hit the paper passing area of the fixing film 13. It is As shown in FIG. 14, the shielding surface 45a is formed between the fixing film 13 and a portion where the cooling air can flow from the discharge unit 55 toward the fixing film 13 in the recording material conveying direction (arrow Y direction). . 15, the shielding surface 45a is designed to prevent the cooling air from the recording material cooling fan 53 from hitting the sheet passing area of the fixing film 13 regardless of the width of the recording material S. As shown in FIG. It is formed over a width larger than the paper area (Wmax).

Further, the fixing cover 45 has side ribs 45b (inner ribs) formed on both end portions of the shielding surface 45a. However, as shown in FIGS. 15 and 16, the side ribs 45b are formed on the center side (inside) of the end portions of the shielding surface 45a in the width direction and outside the maximum paper passing area (Wmax). there is That is, the side ribs 45b are formed in the vicinity of the ends of the maximum sheet passing area of the fixing film 13, and are formed at positions deeper inside the fixing cover 45 than the ends of the shielding surface 45a when viewed in the width direction. In other words, the shielding surface 45a has a protruding wall surface portion 451 that protrudes outward from the side ribs 45b in the width direction on its end side. In the present embodiment, the presence of the protruding wall portion 451 makes it difficult for the cooling air that hits the shielding surface 45 a to flow toward the protruding wall portion 451 side and wrap around the edges to reach the paper passing area of the fixing film 13 .

Further, as shown in FIG. 16, inside the fixing cover 45, a plurality of inner ribs 45c are formed in addition to the side ribs 45b described above. The inner rib 45 c extends from the inner surface of the fixing cover 45 along the outer peripheral surface of the fixing film 13 in the rotational direction. In this embodiment, the side rib 45b and the plurality of inner ribs 45c are formed at the same positions as the plurality of second rectifying ribs 44L and 44R (see FIG. 8) formed in the ventilation hole 38L. That is, the plurality of inner ribs 45c including the side ribs 45b are formed continuously with the second straightening ribs 44L and 44R. The side ribs 45b and the plurality of inner ribs 45c may be formed in the same shape. For example, as shown in FIG. Moreover, it is preferably formed in a substantially U shape when viewed from the width direction.

As described above, in the present embodiment, the fixing cover 45 is used in which the side ribs 45b are formed near the ends of the maximum sheet passing area of the fixing film 13, and the shielding surface 45a is formed so as to protrude from the side ribs 45b. be done. With this fixing cover 45, even if the cooling air from the recording material cooling fan 53 flows toward the fixing film 13, it does not hit the paper passing area of the fixing film 13 due to the blocking surface 45a. In addition, the side ribs 45b prevent the cooling air that hits the shielding surface 45a from entering from the edge side and enters the maximum sheet passing area of the fixing film 13. As shown in FIG. In this way, since the sheet passage area of the fixing film 13 is not cooled by the cooling air, a temperature drop in the sheet passage area of the fixing film 13 can be suppressed.

<Other embodiments>
Note that each of the above-described embodiments can also be applied to a configuration using a roller-shaped fixing roller instead of the fixing film 13 . In addition, the present invention is not limited to the configuration in which the fixing film 13 is heated, and can be applied to a configuration in which a belt-like pressure belt is used instead of the pressure roller 20 and the pressure belt is heated by a heater or the like. In this case, the cooling unit 250 may be arranged on the pressure belt side.

REFERENCE SIGNS LIST 11 heating means (heater) 13 first rotating body (fixing film) 20 second rotating body (pressure roller) 31L (31R) outlet 32L (32R) duct (first duct , second duct), 33L (33R) ... fan (cooling fan), 36L (36R) ... shutter, 38L (38R) ... ventilation hole, 43L (43R) ... first rectifying rib, 44L (44R) ... second rectifying Rib 45 Fixing cover member (fixing cover) 45a Shielding surface 45b Inner rib (side rib) 45c Inner rib 45U Partition wall 200 Fixing device 210 (210A) Fixing unit 250 Cooling unit 451 Protruding wall surface portion 500 Recording material cooling unit N Fixing nip portion S Recording material

Claims (8)

A fixing device for fixing a toner image formed on a recording material to the recording material,
a first rotating body, a heating means for heating the first rotating body, and a fixing device that abuts on the outer peripheral surface of the first rotating body and applies heat and pressure while nipping and conveying the recording material to fix the toner image. a fixing unit having a second rotating body forming a nip portion;
a cooling unit having a fan that generates cooling air; and a duct that blows the cooling air generated by the fan from an air outlet toward a non-sheet-passing area of the first rotating body;
The fixing unit is provided so as to separate the first rotating body and the cooling unit, and the cooling air blown out from the air outlet is taken in at a position facing the air outlet in the width direction intersecting the recording material conveying direction. a fixing cover member having a ventilation hole formed therethrough;
A plurality of first straightening ribs are formed in the outlet so as to be substantially orthogonal to the width direction,
In the ventilation hole, a plurality of second straightening ribs are formed substantially perpendicular to the width direction so as not to overlap the first straightening ribs when viewed from the outlet.
A fixing device characterized by: the cooling unit is provided so as to be able to reciprocate in the width direction with respect to the air outlet, and has a shutter capable of adjusting an opening width of the air outlet according to a paper passing area of each recording material having a different width;
The plurality of second straightening ribs are formed at positions facing each other in the vicinity of the respective ends of the recording material passing through the fixing nip portion on the first rotating body,
2. The fixing device according to claim 1, wherein: The shutter has an opening width of the blower outlet adjusted, and an end portion on the blower outlet side is positioned outside a paper passing area of the recording material passing through the fixing nip portion in the first rotating body.
3. The fixing device according to claim 2, wherein: The fixing cover member has a plurality of inner ribs extending in the rotational direction along the outer peripheral surface of the first rotating body from the inner surface at the same positions as the plurality of second straightening ribs in the width direction.
The fixing device according to any one of claims 1 to 3, characterized in that: a recording material cooling unit provided downstream of the fixing unit in the recording material conveying direction and cooling the recording material by blowing cooling air onto the recording material that has passed through the fixing nip portion;
The fixing cover member is formed on a partition wall in which the ventilation holes are formed, and on a downstream side of the partition wall in the recording material conveying direction, and shields the first rotating body from cooling air from the recording material cooling unit. and a shielding surface that
The shielding surface has a protruding wall portion that protrudes outward from the outermost inner rib in the width direction,
5. The fixing device according to claim 4, wherein: The fixing unit conveys the recording material in the fixing nip portion by center-referenced conveyance with the center in the width direction as a reference;
Two outlets are formed symmetrically with respect to the reference line of the central reference conveyance,
The ventilation holes are formed at positions facing each of the outlets,
The fixing device according to any one of claims 1 to 5, characterized in that: The fans arranged at each of the outlets are the same fan,
7. The fixing device according to claim 6, wherein: A fixing device for fixing a toner image formed on a recording material to the recording material,
a first rotating body, a heating means for heating the first rotating body, and a fixing device that abuts on the outer peripheral surface of the first rotating body and applies heat and pressure while nipping and conveying the recording material to fix the toner image. a fixing unit having a second rotating body forming a nip portion;
a recording material cooling unit that is provided downstream of the fixing unit in the recording material conveying direction and cools the recording material by blowing cooling air onto the recording material that has passed through the fixing nip portion;
a fixing cover member provided in the fixing unit and having a shielding surface that shields the first rotating body from cooling air from the recording material cooling unit;
The fixing cover member extends in the rotation direction along the outer peripheral surface of the first rotating body outside a sheet passing area of the recording material having the maximum width in the width direction intersecting the recording material conveying direction. having ribs,
The shielding surface has a protruding wall portion that protrudes outward from the inner rib in the width direction,
A fixing device characterized by:

Images