JP2004085882A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a fixing device which is practical without requiring wait time and decreasing heat efficiency even when altering the temperature of a fixing member under glossiness control in the fixing device and obtains an image having arbitrary glossiness. <P>SOLUTION: The image forming apparatus is provided with a cooling roller 17r which can be brought into contact with the fixing member and separated therefrom, and has a high glossiness mode or a low glossiness mode. When switching from the high glossiness mode to the low glossiness mode, the cooling roller 17r is brought into contact with the fixing member. When the fixing member reaches the predetermined temperature, the cooling roller 17r is separated from the fixing member. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus including a fixing device used for image formation such as a copying machine, a printer, and a facsimile, and more particularly, to an image forming apparatus including a fixing device using a belt member.
[0002]
[Prior art]
Conventionally, as a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, a fixing rubber roller having an elastic layer and maintained at a predetermined temperature, and being pressed against a fixing rubber roller, 2. Description of the Related Art A heat roller fixing system in which a transfer material having an unfixed toner image formed thereon is heated while being nipped and conveyed by a pressure rubber roller having an elastic layer is often used.
[0003]
However, in this type of apparatus, the heat resistance and heat capacity of the fixing rubber roller are large, so that the warm-up time is long, the temperature inside the elastic layer is high, and the life of the fixing rubber roller is shortened.
[0004]
In addition, many color images have a large solid area, and many of the solid images are other than black. When a hard roller is used in place of the fixing rubber roller, there is a problem that image quality is deteriorated because uneven gloss is generated in accordance with unevenness of a transfer material (recording paper) or a toner layer.
[0005]
In order to solve these problems, an endless belt member (fixing belt) is used as a fixing member, and the fixing belt is supported and stretched by a plurality of roller members. Roller), a pressure roller (external pressure roller) opposed to the support pressure roller across the fixing belt, and a heating member (supporting heat roller) having a heating element for heating the fixing belt inside. An auxiliary nip portion provided on the upstream side of the supporting pressure roller in the rotation direction of the belt, and a fixing nip portion provided between the supporting pressure roller and an external pressure roller (pressure roller) on the recording paper. A fixing device for fixing a toner image is disclosed in, for example, JP-A-10-307496.
[0006]
[Problems to be solved by the invention]
As one of methods for controlling the glossiness in a fixing device using a fixing member (fixing belt) as disclosed in the above heat roller fixing device or the above-mentioned Japanese Patent Application Laid-Open No. 10-307496, a fixing roller and a fixing belt are used. There is a way to change the temperature. However, when the temperature is increased, the switching time can be reduced by lowering the heat capacity of the fixing roller or the fixing belt or by increasing the heat source capacity (the number of watts (W) of the heating element). Since it was difficult to shorten, it was not practical. Although cooling by a fan is possible, a fan is required, and there are problems such as an increase in size and a decrease in heat insulation efficiency in order to secure an air path.
[0007]
The present invention solves the above-mentioned problems, and has no waiting time and does not reduce the thermal efficiency, and is practical and has an arbitrary glossiness even when the temperature of the fixing member is changed in the glossiness control in the fixing device. It is an object of the present invention to provide an image forming apparatus provided with a fixing device capable of obtaining an image having the following.
[0008]
[Means for Solving the Problems]
The object is to form an image by transferring an unfixed toner image onto a transfer material, and then pressing and heating the unfixed toner image by a fixing device having a fixing member to fix the unfixed toner image on the transfer material. In the apparatus, a cooling roller that can be brought into contact with and separated from the fixing member is provided, and a high gloss mode or a low gloss mode is provided. When switching from the high gloss mode to the low gloss mode, the cooling roller is connected to the fixing member. , And when the fixing member reaches a predetermined temperature, the cooling roller is separated from the fixing member (first invention).
[0009]
Further, the above object is to fix the unfixed toner image by transferring the unfixed toner image onto a transfer material, and then pressing and heating the unfixed toner image with a fixing device having a fixing member to fix the unfixed toner image on the transfer material. In the image forming apparatus, a cooling roller that can be separated from the fixing member is provided, and when the cooling roller is separated from the fixing member, the cooling roller is a part of a housing that substantially covers the fixing device. This is achieved by an image forming apparatus (second invention).
[0010]
The present invention provides an image forming apparatus provided with a fixing device that can be used practically and has an arbitrary glossiness without any waiting time and without reducing the thermal efficiency by adopting the above configuration. It is possible.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.
[0012]
An image forming process and each mechanism of an embodiment of an image forming apparatus using a fixing device according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device according to the present invention, and FIG. 2 is an outline of an example of a fixing device using a cooling roller according to the present invention. FIG. 3 is a control block diagram of the fixing device, and FIG. 4 is a diagram illustrating a moving state of a cooling roller with respect to a housing.
[0013]
In FIG. 1, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus YS.
[0014]
An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is provided above the image forming apparatus main body GH. A document D placed on a document table of the automatic document feeder 201 is conveyed by a conveying means, and one side or both sides of the document is scanned and exposed by an optical system of a document image scanning and exposing device 202, and is sent to a line image sensor CCD. Is read. At this time, the original D conveyed from the original platen is determined by the gloss level detection sensor PKa used as a gloss level selecting means to determine the gloss of the original image, the monochrome / color of the original image, and the double-sided image. Done.
[0015]
The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing section, and then to an image writing section (exposure means) 3Y, 3M, 3C. Send a signal to 3K.
[0016]
The automatic document feeder 201 has an automatic double-sided document conveying means. Since the automatic document feeder 201 can continuously read the contents of a large number of documents D conveyed from the document mounting table at once and accumulate it in the storage means (electronic RDH function), the copying function This is conveniently used when copying the contents of many originals, or when transmitting many originals D by facsimile function.
[0017]
The image forming apparatus main body GH is called a tandem-type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 6 as a belt-shaped intermediate transfer body, It is composed of a paper feeder including a paper mechanism (ADU mechanism) and a fixing device 17 as a fixing unit.
[0018]
The image forming unit 10Y that forms a yellow (Y) color image includes a photosensitive drum 1Y as an image forming body, a charging unit 2Y as a Y toner image forming unit disposed around the photosensitive drum 1Y, and an exposure. There is a unit 3Y, a developing device 4Y and an image forming body cleaning unit 8Y. The image forming unit 10M that forms an image of magenta (M) color includes a photosensitive drum 1M as an image forming body, a charging unit 2M as a M toner image forming unit, an exposing unit 3M, a developing device 4M, and an image forming unit. It has a cleaning unit 8M. The image forming section 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image forming body, a charging section 2C as a C toner image forming section, an exposing section 3C, a developing device 4C, and an image forming section. It has a cleaning unit 8C. An image forming unit 10K for forming a black (K) color image includes a photosensitive drum 1K as an image forming body, a charging unit 2K as a K toner image forming unit, an exposing unit 3K, a developing device 4K, and an image forming unit. It has a cleaning unit 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit. The development by the developing devices 4Y, 4M, 4C, and 4K is performed by reversal development in which a development bias in which an AC voltage is superimposed on a DC voltage having the same polarity (negative polarity in the present embodiment) as the polarity of the toner to be used is applied. .
[0019]
The intermediate transfer belt 6 is wound around a plurality of rollers and is rotatably supported.
[0020]
The outline of the image forming process will be described below.
An image of each color formed by the image forming units 10Y, 10M, 10C and 10K is applied with a primary transfer transfer bias by a power source (not shown) having a polarity opposite to that of the toner to be used (positive in this embodiment). By the primary transfer rollers 7Y, 7M, 7C and 7K as the secondary transfer means, the color images (color toner images) are sequentially transferred onto the rotating intermediate transfer belt 6 (primary transfer) and synthesized. You. The recording paper P stored in the paper feed cassettes 20A, 20B, and 20C is fed by a feed roller 21 and a paper feed roller 22A provided in the paper feed cassettes 20A, 20B, and 20C, respectively, and is fed by transport rollers 22B, 22C, and 22D. Then, the sheet is conveyed to a secondary transfer roller 7A as a secondary transfer means via a registration roller 23 and the like, and a color image is collectively transferred onto one surface (front surface) of the recording paper P (secondary transfer).
[0021]
The recording paper P to which the color image has been transferred is subjected to a fixing process by the fixing device 17, is sandwiched by the discharge rollers 24, and is placed on a discharge tray 25 outside the apparatus.
[0022]
The untransferred toner remaining on the peripheral surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K after the transfer is cleaned by the image forming body cleaning means 8Y, 8M, 8C, and 8K and enters the next image forming cycle.
[0023]
On the other hand, after the color image is transferred onto the recording paper P by the secondary transfer roller 7A, the residual toner is removed from the intermediate transfer belt 6 from which the recording paper P is separated by the curvature by the intermediate transfer body cleaning means 8A.
[0024]
Although the above image forming process has been described with reference to color image formation, it goes without saying that not only color image formation but also monochrome image formation and double-sided image formation are performed.
[0025]
The fixing device 17 according to the present invention has a configuration shown in FIG. 2, and includes a fixing belt 27 including an endless belt member as a fixing member, and a support belt 27 that supports the fixing belt 27 on one of inner circumferential surfaces of the fixing belt 27. A supporting pressure roller 17a to be bridged, and a supporting heating roller 17c as a heating member of a belt member having a halogen heater HLa as a heating element and supporting and stretching the fixing belt 27 on the other of the inner peripheral surfaces of the fixing belt 27 And an external pressure roller 17b which comes into contact with the support pressure roller 17a with the fixing belt 27 interposed therebetween and presses (presses) the support pressure roller 17a.
[0026]
A fixing nip Nb is formed between the support pressure roller 17a and the external pressure roller 17b with the fixing belt 27 heated by the support heating roller 17c interposed therebetween, and a fixing nip Nb is formed upstream of the fixing nip Nb (fixing nip Nb The fixing belt 27 and the external pressure roller 17b are opposed to each other to form an auxiliary nip portion Na wound around the external pressure roller 17b between the fixing belt 27 and the external pressure roller 17b. By applying heat and pressure through the auxiliary nip Na and the fixing nip Nb, the toner image (or color toner image) on the recording paper P is fixed.
[0027]
As the fixing belt 27, a nickel electroformed belt having an inner diameter of about 60 to 150 mm and a thickness of about 20 to 80 μm or a heat-resistant resin belt of polyimide or the like having a thickness of about 50 to 200 μm is used as a base. On the outside (outer peripheral surface) of the base, a silicon rubber having a thickness of about 100 to 500 μm is coated, and as a release layer, the surface is subjected to PFA (perfluoroalkoxy) or PTFE coating with a thickness of about 30 to 50 μm, Alternatively, a material coated with a PFA tube is used.
[0028]
The supporting pressure roller 17a is, for example, a cylindrical metal pipe 171a having a thickness of about 2 to 5 mm using a steel material such as STKM (carbon steel pipe for machine structure), and a thickness of 0 mm on the outer peripheral surface of the metal pipe 171a. As a soft roller having an outer diameter of about 25 to 70 mm, a silicon rubber layer 172a of about 0.5 to 5 mm is provided, and a PFA (perfluoroalkoxy) tube 173a having a thickness of about 30 to 70 μm is provided outside the silicon rubber layer 172a. Be composed.
[0029]
The external pressure roller 17b is, for example, a cylindrical metal pipe 171b having a thickness of about 2 to 5 mm using steel or aluminum such as STKM (carbon steel pipe for machine structure) and an outer peripheral surface of the metal pipe 171b. A silicone rubber layer 172b having a thickness of 1 to 3 mm, and a release layer 173b using a PFA (perfluoroalkoxy) tube having a thickness of about 20 to 50 μm outside the silicone rubber layer 172b; It is configured as a soft roller of about 80 mm. Further, a halogen heater HLa as a heating element may be provided inside the external pressure roller 17b as shown by a dotted line in the figure.
[0030]
The supporting and heating roller 17c in which a halogen heater HLa as a heating element for heating the fixing belt 27 is provided is a cylindrical metal pipe 171c having a thickness of about 1 to 2 mm using, for example, aluminum as a base, and A PFA (perfluoroalkoxy) coating 172c having a thickness of about 10 to 30 μm is formed on the outer peripheral surface of the pipe 171c, and is configured as a roller member having an outer diameter of about 30 to 70 mm. Further, as shown by a thick arrow in the drawing, the support heating roller 17c is urged in a direction away from the support pressure roller 17a, and the fixing belt 27 is stretched.
[0031]
The support pressure roller 17a is rotationally driven by a drive motor (not shown), and the fixing belt 27 is supported and conveyed by the rotation of the support pressure roller 17a to be driven to rotate. The external pressure roller 17b may be driven to rotate, the fixing belt 27 may be transported by the external pressure roller 17b, and the fixing belt 27 may be driven to rotate.
[0032]
An auxiliary guide nip Na formed between the fixing belt 27 and the external pressure roller 17b and a fixing nip Nb formed between the support pressure roller 17a and the external pressure roller 17b form an entrance guide plate 17s. Then, the toner image (or the color toner image) on the recording paper P which enters the fixing area through the fixing unit is pressurized and heated, and is fixed and fixed on the recording paper P.
[0033]
Further, a temperature sensor TS1 is provided as a temperature detecting means that comes into contact with the support heating roller 17c, and controls the temperature of the support heating roller 17c. Further, the fixing belt 27 may be provided with a temperature sensor TS2 as temperature detecting means to control the temperature of the fixing belt 27. Of course, the temperature detecting means can be provided not only on one side but on both sides.
[0034]
According to the present invention, in the fixing device 17 described above with reference to FIG. A roller member is provided, and the temperature of the fixing belt 27 at the time of fixing is changed by moving the cooling roller 17r toward and away from the fixing belt 27 to control the glossiness of the fixed image. The solid line indicates the contact state, and the dotted line indicates the separated state. In the separated state, the support heating roller 17c is moved to a position shown by a dotted line by an elastic member such as a spring (not shown), and the temperature sensors TS1 and TS2 are also moved accordingly.
[0035]
More specifically, as will be described later, image formation is performed in the high gloss mode or the low gloss mode, and when the mode is switched from the high gloss mode to the low gloss mode (the image forming command in the high gloss mode). When the image forming command in the low gloss mode is input immediately after the operation, the gloss mode command includes the input from the operation unit of the image forming apparatus and the image forming command output apparatus, and the gloss level. When the control unit selects each glossiness mode based on the detection sensor PKa), the cooling roller 17r is brought into contact with the fixing belt 27, and when the fixing belt 27 reaches a predetermined temperature, the cooling roller 17r is fixed to the fixing belt. 27. That is, when an image command in the low gloss mode is input immediately after the high gloss mode image formation command, the halogen heater HLa is turned off, and the support heating roller 17c and the fixing belt 27 are low gloss by natural heat radiation. The cooling roller 17r is moved and brought into contact with the fixing belt 27 because it takes several tens of seconds to several minutes.
[0036]
As shown in FIG. 3, in the normal image formation, the support heating roller 17c is heated to, for example, about 180 to 200 ° C. by turning on (lighting) a halogen heater as a heating element, and the fixing belt 27 is heated by the temperature sensors TS1 and TS2. When the temperature is maintained at about 160 to 180 ° C., for example, when a start button is pressed from the operation unit (an image formation command is input), the image forming program P1 stored in the ROM of the storage unit is opened. The processing is executed through the control unit to form an image of a monochrome image or a color image. Normal image formation is performed in the low gloss mode.
[0037]
In the standby state of the image forming apparatus, in the case of the present embodiment, the temperature of the supporting and heating roller 17c is set to a low gloss mode temperature, which is the same as that during normal image formation, for example, about 180 to 200 ° C. However, for example, when an image formation command is input by a start button of the operation unit (the start button is turned on), if the image formation command is an image formation in a case where the low glossiness mode is selected, the image formation is performed. The execution of the program P1 waits for the entry of an unfixed image. However, when the image formation command is for image formation based on the high gloss mode selection in the operation unit, the halogen heater HLa is turned on and the support heating roller 17c is turned on. Temperature heaters TS1 and TS2 to increase the temperature of the halogen heater HLa so that the temperature of To change the control. Since the supporting heating roller 17c has a small thickness and is designed to have a low heat capacity, the temperature reaches a predetermined high gloss temperature within a few seconds, an unfixed image is formed, and the upstream side of the fixing nip portion Nb is formed. The mode change of the fixing device to the high glossiness mode is completed before entering the auxiliary nip Na.
[0038]
When an image command in the low gloss mode is input immediately after an image formation command in the high gloss mode by selection on the operation unit, the high gloss image forming program P2 in the storage unit ROM is executed. The halogen heater HLa is turned off (off), and in the present invention, the cooling roller 17r is moved to contact the fixing belt 27 to cool the fixing belt 27 to, for example, about 160 to 180 ° C., without providing a waiting time. An image is formed in the low gloss mode. Of course, it is also possible to use the temperature of the supporting and heating roller 17c to determine the cooling state.
[0039]
The cooling roller 17r varies depending on the frequency of contact with the fixing belt 27 heated to, for example, about 180 to 200 ° C., but frequently switches to about 80 to 100 ° C. immediately after a WUT (warming-up time). ) Is held at a low temperature of about 120 to 140 ° C. and has a large heat capacity. Therefore, heat is removed from the fixing belt 27 and the supporting heating roller 17 c via the fixing belt 27, and the unfixed image is removed. Before the toner enters the auxiliary nip Na, the fixing belt 27 and the support heating roller 17c are lowered to the low gloss mode temperature. After the temperature of the fixing belt 27 and the supporting heating roller 17c have been lowered to a predetermined low gloss mode temperature, the cooling roller 17r is separated from the fixing belt 27, and the temperature of the cooling roller 17r is lowered by heat radiation. Prepare for switching to low gloss mode.
[0040]
The cooling roller 17r operates only when the mode is switched from the high gloss mode to the low gloss mode, so that in a normal use state, there is no case where heat radiation cannot keep up.
[0041]
In addition, the member that contacts and separates the cooling roller 17r may be the external pressure roller 17b.
[0042]
In the present embodiment, the case of two levels of the high gloss mode and the low gloss mode has been described, but it goes without saying that it is effective to have a multi-stage gloss mode.
[0043]
In this embodiment, the case where the present invention is applied to a belt fixing device using a fixing member (fixing belt) including a belt member has been described. However, since the belt member has a low heat capacity, the heating speed is high, that is, high gloss. This is because switching from the degree mode to the low gloss mode is quick, and the combination with the present invention is particularly suitable. Even if the fixing member is a fixing roller, the present invention is still effective.
[0044]
According to the present invention, as described above, in order to control glossiness by temperature, a cooling roller for cooling is brought into contact (contact) with a belt member or a roller member during cooling.
[0045]
Also, in order to increase the heat radiation efficiency of the cooling roller 17r while maintaining the heat insulation performance of the fixing device 17 itself, as shown in FIG. A fixing casing TKa having a rectangular gap Ha into which the fixing roller 17r is fitted is provided, and in a state where the cooling roller 17r is separated from the fixing belt 27 as a fixing member, the cooling roller 17r is fitted into the fixing casing TKa so that the cooling roller 17r is a casing. The cooling roller 17r is configured as a part of the body so that heat can be easily radiated to the outside of the fixing device 17 and heat loss due to hot air flowing out of the fixing device 17 from the gap Ha is suppressed. It is also possible. When the cooling roller 17r is absent, heat escapes from the gap Ha. However, when the gap Ha is closed by the cooling roller 17r, the cooling roller 17r substantially becomes part of the fixing casing TKa as a housing. Thus, the gap Ha is filled to prevent the heat from the fixing device 17 from escaping. Thus, the fixing device 17 is kept warm with no place for heat to escape, while the cooling roller 17r, part of which is exposed to the outside of the fixing device 17 from the gap Ha, is cooled.
[0046]
As described above, when the cooling roller 17r is separated from the fixing belt 27, the cooling roller 17r becomes a part of a housing that substantially covers the fixing device 17.
[0047]
Further, in the fixing device 17 having the above-described configuration, in order to cope with various use situations (for example, frequent switching of glossiness), a radiating fin (not shown) for increasing the heat radiation efficiency from the cooling roller 17r is connected to the end of the cooling roller 17r. Or cooling with a cooling fan.
[0048]
Further, in order for the cooling roller 17r to contact the fixing belt 27, the temperature of the fixing belt 27 and the like is reduced. That is, since the heat of the fixing device 17 is to be discharged, the gap Ha generated by the contact of the cooling roller 17r with the fixing belt 27 serves as a heat discharge path and contributes to cooling of the fixing belt 27 and the like.
[0049]
As described above, the fixing belt 27 is driven by the support pressure roller 17a or the external pressure roller 17b, and the recording paper holding the toner image (toner image) conveyed to the fixing area by the entry guide plate 17s or the like. P is pressed by an appropriate pressing force by an auxiliary nip portion Na provided at the entrance, and is pre-fixed, and is externally pressed by a supporting pressure roller 17a around which a fixing belt 27 is wound with the recording paper P interposed therebetween. The toner image (toner image) is fixed on the recording paper P by the heat of the fixing belt 27 and the pressure by the external pressure roller 17b in the fixing nip Nb where the pressure is applied by the fixing roller 17b. At this time, since the rubber of the fixing belt 27 is brought into contact with the toner layer (toner image) on the recording paper P via a rubber or a thin release layer, the rubber is deformed, and the recording paper P and the toner layer are deformed. The toner image (toner image) is maintained at an appropriate gloss because the toner image (toner image) is uniformly fixed without unevenness of gloss. It is separated from the fixing belt 27.
[0050]
According to the present invention having the above-described configuration, a practical image having any glossiness can be obtained without waiting time and without reducing thermal efficiency.
[0051]
【The invention's effect】
According to the present invention, it is possible to provide an image forming apparatus including a fixing device that can be used practically and has an arbitrary glossiness without any waiting time and without lowering thermal efficiency.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device according to the present invention.
FIG. 2 is a schematic sectional configuration diagram of an example of a fixing device using a cooling roller according to the present invention.
FIG. 3 is a control block diagram of the fixing device.
FIG. 4 is a diagram illustrating a moving state of a cooling roller with respect to a housing.
[Explanation of symbols]
1Y, 1M, 1C, 1K Photoconductor drums 2Y, 2M, 2C, 2K Charging means 3Y, 3M, 3C, 3K Exposure means 4Y, 4M, 4C, 4K Developing device 7A Secondary transfer rollers 7Y, 7M, 7C, 7K 1 Next transfer roller 8A Intermediate transfer body cleaning means 8Y, 8M, 8C, 8K Image forming body cleaning means 10Y, 10M, 10C, 10K Image forming unit 17 Fixing device 17a Support pressure roller 17b External pressure roller 17c Support heat roller 17r Cooling Roller 17s Entry guide plate 27 Fixing belt HLa Halogen heater Na Auxiliary nip Nb Fixing nip TKa Fixing casing TS1, TS2 Temperature sensor P Recording paper

Claims (4)

After transferring the unfixed toner image onto the transfer material, the image forming apparatus presses and heats the unfixed toner image with a fixing device having a fixing member, and fixes the unfixed toner image on the transfer material.
Providing a cooling roller that can contact and separate from the fixing member,
Has high gloss mode or low gloss mode,
When switching from the high gloss mode to the low gloss mode, the cooling roller is brought into contact with the fixing member, and when the fixing member reaches a predetermined temperature, the cooling roller is separated from the fixing member. Characteristic image forming apparatus. Providing temperature detecting means for detecting the temperature of the fixing member or the heating member for heating the fixing member, or both of them, and performing the contact / separation control of the cooling roller based on the temperature detected by the temperature detecting means. The image forming apparatus according to claim 1, wherein: The image forming apparatus according to claim 1, wherein the fixing member is a belt member. After transferring the unfixed toner image onto the transfer material, the image forming apparatus presses and heats the unfixed toner image with a fixing device having a fixing member, and fixes the unfixed toner image on the transfer material.
Providing a cooling roller that can contact and separate from the fixing member,
The image forming apparatus, wherein when the cooling roller is separated from the fixing member, the cooling roller becomes a part of a housing that substantially covers the fixing device.

Images