JP6727915B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming equipment. For example, a suction unit that is applied to an image forming apparatus such as a copying machine, a printer, or a facsimile that forms a toner image on a recording medium (sheet) by using an electrophotographic system, and particularly a suction unit that collects dust generated in a fixing process. Be prepared.

An electrophotographic image forming apparatus forms a toner image on a recording medium (sheet) using a toner containing a release agent (wax), and heats and presses the toner image in a fixing device to perform a fixing process. ..

It is known that during the fixing process, the wax contained in the toner is vaporized, and immediately after that, it is condensed and turned into particles in the air. It is known that many of the wax particles (hereinafter also referred to as dust) after condensation exist and float near the fixing member of the fixing device. Such dust may contain an unpleasant odor, and may adhere to the internal mechanism of the image forming apparatus to hinder its operation. Therefore, appropriate measures must be taken against dust.

An image forming apparatus is known that can extend the life of the filter without increasing the size of the exhaust path by disposing a filter that collects dust generated in the fixing process and changing the attitude of the filter. (Patent Document 1). More specifically, a filter is provided in the middle of the exhaust path of air containing dust generated in the fixing process, and the orientation of the filter is set in the direction parallel to the flow of air flowing along the exhaust path and the direction of the flow of air. And a posture changing means for changing between the crossing direction and the crossing direction.

JP, 2013-190520, A

However, the configuration of Patent Document 1 complicates the filter replacement work when the filter reaches the end of its life. The reason is that the filter is installed in the middle of the exhaust path, so it takes time to access the filter member, and the filter is movable, so the movable mechanism must be released before removing the filter. is there.

An object of the present invention is to provide an image forming equipment which can not, to facilitate replacement of filters for collecting dust generated in the fixing process by increasing the size of the apparatus.

An image forming apparatus according to the present invention transfers a recording material from a transfer unit that transfers a toner image onto a recording medium, a fixing unit that heats and fixes the toner image on the recording medium onto the recording medium, and the transfer unit to the fixing unit. A duct having a transport path, a fan that sucks in air, and a filter that filters dust, and that has a first opening through which air passes and a second opening that is not covered by the filter; A shutter that opens and closes the opening; a first mode in which the shutter closes the second opening to suck air in the image forming apparatus into the duct through the filter; A second mode in which the air in the image forming apparatus is sucked into the duct with the second opening opened, and a control unit that controls the opening and closing of the shutter to execute, and the filter is It is characterized in that it is provided so as to face the transport path, and the second opening is provided at a side surface of the duct that faces the fixing portion.

According to the present invention, it is possible to facilitate the replacement work of the filter that collects the dust generated in the fixing process without increasing the size of the device.

Schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention Details of the fixing device regarding the dust generation phenomenon Explanatory drawing about arrangement|positioning of the suction unit which concerns on embodiment of this invention Explanatory drawing regarding the operation of the suction unit according to the embodiment of the present invention. Explanatory drawing about the structure of the suction unit which concerns on embodiment of this invention. Explanatory drawing about the structure of the suction unit which concerns on embodiment of this invention. Illustration of the nature of dust Block diagram of an image forming apparatus according to an embodiment of the present invention Flowchart of the image forming apparatus according to the embodiment of the present invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<<First Embodiment>>
(Image forming device)
FIG. 1 is a schematic sectional view of an image forming apparatus 1 according to an embodiment of the present invention, which includes a filter unit 50 as a suction unit. The image forming apparatus 1 is a four-color full-color laser beam printer (color image forming apparatus) using an electrophotographic process. The image forming apparatus 1 includes four image forming stations (process cartridges) 5Y, 5M, 5C, and 5K as the image forming unit 5 from first to fourth. The first to fourth image forming stations 5Y, 5M, 5C, and 5K are located substantially in the center of the apparatus main body 1 and are arranged substantially horizontally in parallel from left to right in FIG.

Each image forming station has a similar electrophotographic process mechanism. Each of the image forming stations 5Y, 5M, 5C and 5K of the present embodiment has a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a drum) 6 as an image bearing member on which an image is formed. Further, it has a cleaning member 41 as a process means acting on the drum 6, a developing unit 9 and a charging roller (not shown).

In the first image forming station 5Y, a yellow (Y) color developer (hereinafter referred to as toner) is stored in the toner storage chamber of the developing unit 9. Further, in the second image forming station 5M, magenta (M) color toner is stored in the toner storage chamber of the developing unit 9. Further, in the third image forming station 5C, cyan (C) color toner is stored in the toner storage chamber of the developing unit 9. Then, in the fourth image forming station 5K, black (K) color toner is stored in the toner storage chamber of the developing unit 9.

Below the image forming stations 5Y, 5M, 5C, and 5K (vertical direction), a laser scanner unit 8 as image information exposure means for each drum 6 is arranged. An intermediate transfer belt unit 10 is provided above (vertical direction) the image forming stations 5Y, 5M, 5C, and 5K.

The intermediate transfer unit 10 includes an intermediate transfer belt (hereinafter referred to as a belt) 10c and a driving roller 10a that drives the intermediate transfer belt 10c. Inside the belt 10c, first to fourth four primary transfer rollers 11 are arranged in parallel so as to face the respective drums 6 of the image forming stations 5Y, 5M, 5C and 5K. The drum 6 of each of the image forming stations 5Y, 5M, 5C, and 5K has an upper surface contacting the lower surface of the belt 10c at the position of each primary transfer roller 11, and the contact portion is a primary transfer portion.

A secondary transfer roller 12 is arranged outside the bent portion of the drive roller 10a that rotationally drives the belt 10c. The contact portion 12a between the belt 10c and the secondary transfer roller 12 forms a secondary transfer portion that is a transfer unit.

A transfer belt cleaning device 10d is arranged outside the bent portion of the tension roller 10b that applies tension to the belt 10c. Below the image forming apparatus 1, a paper cassette 3 is arranged.

In FIG. 1, the recording medium (paper) picked up from the cassette 3 is conveyed upward. A fixing device (fixing unit) including a roller pair of a feeding roller 4a and a retard roller 4b, a registration roller pair 4c, a secondary transfer roller 12, and a fixing belt 105 in this order from the lower side to the upper side in the vertical direction. ) 103, a guide member 15, and a pair of discharge rollers 14 are provided. A discharge tray (discharge sheet stacking unit) 16 for discharging the sheet on which the image is recorded is provided below the image reader 2 (vertical direction).

In FIG. 1, reference numeral 1000 denotes a control unit described in detail later.

(Image forming operation)
The operation for forming a full-color image is as follows. The drums 6 of the first to fourth image forming stations 5Y, 5M, 5C, and 5K are rotationally driven at a predetermined speed in accordance with the image forming timing. As a result, the belt 10c is rotationally driven in the forward direction of the rotation of the drum at a speed corresponding to the speed of the drum 6. Then, the laser scanner unit 8 is also driven.

In synchronization with this driving, in each of the image forming stations 5Y, 5M, 5C and 5K, the surface of the drum 6 is uniformly charged to a predetermined polarity and potential by a charging roller (not shown) to which a predetermined charging bias is applied. .. Then, the laser scanner unit 8 scans and exposes the surface of each drum 6 with a laser beam modulated according to the image information signal of each color of Y, M, C, and K. As a result, an electrostatic latent image corresponding to the image information signal of the corresponding color is formed on the surface of each drum 6. The formed electrostatic latent image is developed as a toner image (developer image) by the developing unit 9.

The toner images of the respective colors YMCK formed as described above are primary-transferred on the belt 10c in the primary transfer portion. In this manner, four full-color unfixed toner images of Y color+M color+C color+K color are compositely formed on the moving belt 10c. Then, the unfixed toner image is conveyed by the rotation of the belt 10c and reaches the contact portion 12a which is a transfer portion. In each image forming station 5, the surface of the drum 6 after the primary transfer of the toner image onto the belt 10c is cleaned of residual toner by the cleaning unit 41, and is used in the next image forming process.

On the other hand, the sheet in the cassette 3 is fed by one sheet by the feeding roller 4a and the retard roller 4b at a predetermined control timing and is conveyed to the registration roller pair 4c. The sheet is conveyed to the secondary transfer portion by the registration roller pair 4 at a predetermined control timing. A secondary transfer bias having a polarity opposite to the regular charging polarity of the toner is applied to the secondary transfer roller 12 at a predetermined control timing. As a result, the four-color toner images on the belt 10c are secondarily transferred onto the surface of the paper P all together while the paper is nipped and conveyed through the secondary transfer portion.

The sheet P exiting the secondary transfer portion is separated from the belt 10c, and a fixing nip portion (nip portion) is formed by a fixing belt 105 that is an endless belt and a roller (pressure roller) 102 that faces the fixing belt 105. And the toner image is heated and fixed on the paper. The sheet exiting the fixing device 103 is discharged to the discharge tray 16 via the discharge roller pair 14. The residual toner remaining on the surface of the belt 10c after the secondary transfer of the toner image onto the paper is removed from the belt surface by the transfer belt cleaning device 10d, and the cleaned belt surface is subjected to the next image forming step.

(Dust generation)
Next, the generation of dust due to the release agent (hereinafter referred to as wax) contained in the target toner in the present embodiment and the nature of dust will be described.

1) Wax contained in toner There is a possibility that a phenomenon called offset in which toner is transferred to the fixing belt 105 may occur during the fixing process, and such an offset phenomenon causes a problem such as an image defect. .. Therefore, the wax is included in the toner so that the wax exudes from the toner during the fixing process. As a result, the wax melted by heating is present at the interface between the fixing belt 105 and the toner image on the sheet, and the offset phenomenon can be prevented (release action).

In this embodiment, paraffin wax is used, and the melting point of the wax is about 75°C. The melting point is set so that when the nip portion is maintained at a target set temperature of 170° C., the wax in the toner is instantly melted and oozes out to the interface between the toner image and the fixing belt 105.

In this fixing process, part of the wax is vaporized (volatilized). The vaporized wax component is cooled in air and condensed, and immediately after that, fine particles (dust) having a particle size of several nm to several hundreds nm may exist. However, it is presumed that most of them are fine particles having a particle diameter of 100 nm or less. Since this dust is a wax component, it has adhesiveness and may adhere to various places inside the image forming apparatus 1 to cause a problem.

2) Location of Dust Generation Next, location of dust generation will be described. FIG. 2 is a detailed view of the fixing device 103 (FIG. 1) regarding the dust generation phenomenon. The paper P on which the toner image S is placed is being nipped and conveyed in the nip portion 101b, and dust is generated. The wax that has exuded from the toner S on the paper P intervenes at the interface between the fixing belt 105 and the toner image, but part of the wax moves to the fixing belt 105 and is conveyed on the fixing belt 105. Is heated in the process.

The temperature of the surface of the fixing belt 105 decreases to about 100° C. due to the contact with the paper P in the nip portion 101b, but the temperature of the base layer on the back surface of the fixing belt 105 is kept high by the contact with the heater 101a. There is. Therefore, after the fixing belt 105 passes through the nip portion 101b, the heat of the base layer kept at a high temperature is transferred to the surface of the fixing belt 105. Therefore, the surface temperature of the fixing belt 105 rises after passing through the nip portion 101b in the process of the fixing belt 105 rotating in the R105 direction (the opposing pressure roller rotates in the R102 direction), and the nip The highest temperature is reached near the entrance side of the portion 101b.

As shown in FIG. 2A, when a part of the leading edge of the sheet P has passed through the nip portion 101b, the wax transferred from the toner image S to the fixing belt 105 exists only in the area 135a. Since the temperature of this region 135a is low, the wax does not volatilize and no dust is generated.

However, as shown in FIG. 2B, when the paper P further advances in the X direction in the nip portion 101b, the wax exists on the entire circumference (area 135b) of the fixing belt 105, and the entrance of the nip portion 101b becomes high in temperature. The wax evaporates near the side, that is, in the region 135c. The volatilized wax immediately begins to condense, and thus a large amount of dust is present near the entrance of the nip portion 101b (shown as dust D in FIG. 2B).

(Suction unit)
Next, the filter unit 50 as a suction unit will be described with reference to FIGS. First, the arrangement of the filter unit 50 is shown in FIG. FIG. 3A is a perspective view and FIG. 3B is a sectional view. The operation of the filter unit 50 is shown in FIG. FIG. 4A shows an exploded perspective view of the filter unit 50, and FIG. 4B shows air in and out of the filter unit 50. Then, the configuration of the filter unit 50 will be described with reference to FIGS. 5A and 5B.

As shown in FIG. 3B, the filter unit 50 shown in FIG. 3A includes a nip portion 101b of the fixing device 103 and a transfer portion (secondary transfer portion) of the secondary transfer roller 12 which is a transfer unit. Located in between. More specifically, the filter unit 50 is arranged in the vicinity of the fixing belt 105, which is a dust generation site, and at a position facing the paper P.

In FIG. 3A, 400 is a sheet inlet and 550 is a sheet outlet.

An opening (first opening) of the duct 52 shown in FIG. 4A is formed by the fan 61, which is an airflow generating unit (airflow generating unit) as a suction unit shown in FIGS. 3A and 4A. It is configured to suck the air containing the dust D from the air 52a. The blower fan type fan 61 takes in the air in the duct 52 through the intake port 61a and exhausts it to the outside of the image forming apparatus through the exhaust port 61b.

Here, in the opening 52a provided on the most upstream side (inlet) of the suction path in the duct 52, a static filter member, which is a plate-shaped filter material for filtering (removing) dust from sucked air as described later in detail, is provided. An electrically non-woven fabric filter (filter) 51 is fixedly installed. However, the blower fan type fan 61, which is characterized by high static pressure, can secure a constant air volume even if there is a ventilation resistor such as the filter 51.

The filter 51 (fibers holding static electricity is formed into a non-woven fabric) provided at such a position of the opening 52a so as to close the opening 52a to filter (remove) dust with high efficiency while having low ventilation resistance. be able to.

When the direction orthogonal to the transport direction (X direction in FIG. 2) of the paper P is the longitudinal direction within the plane where the nip portion 101b is formed, the longitudinal direction of the filter 51 is constant with respect to the longitudinal direction of the fixing device 103. Has a length of (approximately equal to or more). In this embodiment, they are substantially the same. In this way, the dust generated from the wax transferred from the toner image on the sheet P to the fixing belt 105 can be reliably collected by the filter 51 in the longitudinal direction of the fixing belt 105.

Unlike the conventional example (Patent Document 1) in which a filter is provided in the middle of the exhaust path, the exhaust path from the inlet of the duct 52 to the filter can be omitted in this embodiment. As described above, by providing the filter 51 at the inlet of the duct 52, the filter unit 50 can be easily miniaturized in the present embodiment. With such an arrangement, the filter unit 50 can be downsized, and at the same time, the air passing air velocity at the opening 52a (FIG. 4A) which is the inlet of the duct can be made uniform in the longitudinal direction.

Further, by disposing the filter 51, which is a ventilation resistor, in the opening 52a (FIG. 4A), it is possible to maintain a constant negative pressure in the entire back surface region of the filter 51. That is, the negative pressures at the points 53a, 53b, and 53c shown in FIG. 4B have substantially the same value. This is because the ventilation resistance of the filter 51 is significantly higher than the ventilation resistance in the duct 52.

If the negative pressures at the points 53a, 53b, and 53c are at the same level, the wind speed of the air F4 sucked by the filter 51 is made uniform over the entire surface of the filter 51. As a result of uniforming the wind speed, the filter unit 50 can efficiently collect the dust generated from the fixing belt 105 (with a minimum air volume).

Here, in addition to the opening 52a as the first opening, the duct 52 is provided with an opening 200 as a second opening as shown in FIG. 5A (a), and the opening 200 is an opening/closing means. It can be opened and closed by 300. The opening portion 200 is provided on the side farther from the filter 51 than between the transfer portion and the fixing portion (conveyance path of the paper P). That is, the filter 51 is provided on the side of the duct 52 closer to the opening 200.

The opening/closing means 300 is driven by a lid (shutter) 301 for covering the opening, a rotary shaft 302 provided at one end of the lid 301 for rotating the lid 301 with respect to the duct 52, a transmission gear 303 for rotating the rotary shaft, and a transmission gear. And a drive motor 305 for driving the drive gear.

The drive motor 305 is controlled by the controller 1000 (FIG. 1) and can rotate in the forward and reverse directions. When the drive motor 305 rotates forward, the lid 301 rotates counterclockwise to open the opening 200 (FIG. 5A(a)). When the drive motor 305 rotates in the reverse direction, the lid 301 rotates clockwise to close the opening 300 (FIG. 5A(b)).

The control unit 1000 (FIG. 1) allows the first mode (first mode) or the first mode (first mode) from the group including the first and second modes so that the first and second suction paths can be selected as the suction path. The second mode (second mode) can be selected by the controller 1000. In the present embodiment, only one of the first mode and the second mode can be selected by the control unit 1000 (that is, it is an alternative).

In the first mode, the air sucked into the duct 52 is passed through the filter 51 with the lid 301 rotating clockwise to close the opening 200. On the other hand, in the second mode, the lid 301 rotates counterclockwise to allow the air sucked into the duct 52 to pass through the opening 200 with the opening 200 open. This is because the ventilation resistance of the filter 51 is significantly higher than the ventilation resistance of the opening 200.

In the present embodiment, it is possible to switch between exhausting through the filter 51 and exhausting without passing through the filter 51, so that the life of the filter 51 can be extended. Further, since it is realized by one fan 61 and duct 52, the size of the main body can be reduced.

Further, in the present embodiment, the filter 51 is fixedly arranged, and switching between the first mode in which the filter 51 is passed and the second mode in which the filter 51 is not passed is performed by the opening/closing means 300 not related to the filter 51. .. For this reason, it is not necessary to release the movable mechanism at the time of filter replacement work as in the case where a so-called filter has a movable mechanism. This facilitates the removal (replacement) work of the filter. Since the filter 51 is provided at the inlet (upstream side) of the exhaust path, it is easy to access the filter 51 during the removal (replacement) operation of the filter (FIG. 5B).

(Property of dust and proper use of the first and second modes)
Next, the characteristics of dust will be described in detail, and how to use the first mode and the second mode will be described. First, it is known that the size of dust increases at high temperatures. As shown in FIG. 6, when the high boiling point substance 20 having a boiling point of 150 to 200° C. is placed on the heating source 20 a and heated to around 200° C., a volatile substance 21 a of the high boiling point substance 20 is generated. The volatile matter 21a immediately falls below the boiling point temperature when it comes into contact with normal temperature air, so it condenses in the air and changes into fine particles (dust) 21b having a particle size of several nm to several tens nm.

At this time, aggregation/particulation of gas in the air is hindered as the temperature in the air increases. This is because the vapor pressure of the gas increases as the temperature in the air increases, and the gas molecules can easily maintain the gas state. As a result, the number of generated dust particles decreases as the air temperature increases.

It is known that the dusts 21b generated in the above process move in the air by the Brownian motion, so they collide with each other to coalesce and grow into dusts 21c having a larger particle size. This growth is promoted as the dust moves more actively, in other words, as the air temperature is higher. As a result, the particle size of the dust generated from the fixing belt 105 increases as the space temperature near the fixing belt 105 increases, and the number of dust particles decreases.

It should be noted that the increase in size of the dust gradually slows and stops when the size of the dust exceeds a certain size. It is presumed that this is because Brownian motion becomes inactive when the diameter of the dust increases due to coalescence, and the frequency of collision between particles decreases.

Therefore, it can be said that as the atmosphere becomes hotter and the size of the dust is promoted, the dust stays in the fixing device (such as adhering to the inner wall of the fixing device), and as a result, is less likely to be diffused outside the fixing device.

As described above, in the present embodiment, when the ambient temperature around the fixing device is low and the dust is easily diffused to the outside of the fixing device (at the time of start-up), the opening mode is set to the first mode in which the fan 61 is operated. The dust is positively collected by switching and the filter 51. On the other hand, when the ambient temperature around the fixing device is high and it is difficult to diffuse the dust to the outside of the fixing device (10 minutes after the image forming operation is started), the fan 61 is operated with the opening portion 200 in the open state. Switching to the mode, the filter 51 does not actively collect dust.

It should be noted that in this embodiment, the fan 61 is prevented from operating with the opening 200 in the closed state before 10 minutes have elapsed from the start of the image forming operation.

(Control flow)
Next, the control for switching between the first mode and the second mode will be described. 7 and 8 show a block diagram and a flowchart of this embodiment. Here, in the present embodiment, the output means for outputting the continuous sheet passing time is used as the output means for outputting the information indicating the dust generation state (the means for detecting the timing of switching to the second mode).

The lid 301 that closes the opening 200 shown in FIG. 5A (a) is opened and closed by the power of the drive motor 305, and the control of the drive motor 305 is executed by the CPU 500 (FIG. 7) in the control unit 1000 (FIG. 1). It

Although not shown in FIG. 8, at the time of start-up, a state of the first mode in which the opening 200 is closed and air is exhausted through the filter 51 is set. When an image forming instruction is input, the image forming operation is started as shown in FIG. 8 (S100). When the image forming operation is started, it is confirmed whether or not the continuous paper feeding time has passed 10 minutes (S101). When the continuous sheet feeding time has passed 10 minutes, the drive motor 305 is normally rotated and the lid 301 is rotated counterclockwise to change the opening 200 from the closed state to the open state as the second mode ( S102).

Then, it is confirmed whether or not the image formation is completed with the opening 200 kept open (S103). During image formation, the lid 301 remains open. When the image formation is completed, the drive motor 305 is rotated in the reverse direction, the lid 301 is rotated, and the opening 200 is closed (S104).

In this embodiment, the dust (particles of 100 nm or less) to be handled increases in number for a few minutes after the start of image formation, so the opening 200 is always closed at the end of image formation. Then, at the next start-up, the state of the first mode in which the air is exhausted through the filter 51 with the opening 200 closed is set.

The output means for outputting the information indicating the dust generation state (means for detecting the timing of switching to the second mode) is not limited to the output means for outputting the continuous paper passage time. The number of sheets to be continuously fed may be used instead of the continuous sheet feeding time, the temperature inside the machine may be determined by the temperature sensor inside the image forming section, or the temperature sensor dedicated to the fixing device may be used. It may be provided and the temperature may be directly judged.

According to the present embodiment, since the filter that collects the dust generated in the fixing process is disposed at the exhaust path inlet (upstream side), the filter can be easily accessed during the replacement work. Then, while the opening (the second opening) that can be opened and closed is arranged in a part of the duct, while the filter that is provided so as to close the first opening is fixedly arranged, the movable mechanism is released during the replacement work. Since it is not necessary, the work of removing the filter becomes easy. Therefore, it is possible to provide an image forming apparatus in which filter replacement work is easy.

Then, according to the present embodiment, when it is necessary to collect the dust, exhaust the gas through the filter, and when it is not necessary to collect the dust, the gas is exhausted without passing through the filter, thereby extending the service life of the filter. It can also be planned.

(Modification)
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof.

(Modification 1)
(Modification)
Although the preferred embodiment of the present invention has been described in the above embodiment, the present invention is not limited to this, and various modifications can be made within the scope of the present invention.

(Modification 1)
In the above-described embodiment, the fixing member is heated by the heater as the fixing portion, but the present invention is not limited to this, and the electromagnetic induction heating, the lamp heating, the fixing belt itself generates heat, and the like. May be.

Further, in the above-described embodiment, the nip portion is formed by the fixing belt 105, which is an endless belt, and the pressure roller 102 as the fixing portion, but the present invention is not limited to this. For example, a fixing roller may be used instead of the fixing belt, or an endless belt may be used instead of the pressure roller.

Then, the case where the rotating body and the rotating body for pressurizing as the pressing body presses the fixing rotating body is shown, but the rotating body as the facing body, not as the pressing body, presses from the fixing belt as the fixing rotating body. The same can be applied to the case. Here, the facing member is a member that faces the fixing rotating member, forms a fixing nip portion by being in pressure contact with the fixing rotating member, and holds the moving recording material in the fixing nip portion.

(Modification 2)
In the above-described embodiment, the sheet P is described as the recording medium, but the recording medium is not limited to the sheet. Generally, a recording medium is a sheet-shaped member on which a toner image is formed by an image forming apparatus, and includes, for example, standard or irregular standard paper, cardboard, thin paper, envelopes, postcards, stickers, resin sheets, OHP sheets, Includes glossy paper. Note that, in the above-described embodiment, for the sake of convenience, the term “paper passing” is used for description, but the recording medium in the present invention is not limited to paper.

(Modification 3)
In the above-described embodiment, the description is based on the fixing device that fixes the unfixed toner image on the sheet, but the present invention is not limited to this, and the toner image that is supposedly attached to the sheet is improved in order to improve the gloss of the image. The same can be applied to a device that heats and pressurizes (also called a fixing device in this case).

12a..Contact part (transfer part), 51..filter, 52..duct, 61..fan, 103..fixing device, 200..opening part, 300..opening/closing means, 500..control part, P ..Paper

Claims (3)

A transfer unit for transferring the toner image to the recording medium,
A fixing portion for heating and fixing the bets toner image record medium to a recording medium,
A transport path for transporting the recording material from the transfer unit to the fixing unit,
A duct that is covered with a fan that sucks in air and a filter that filters dust, and has a first opening through which air passes and a second opening that is not covered with a filter,
A shutter for opening and closing the second opening,
A first mode in which the shutter closes the second opening to suck air in the image forming apparatus into the duct through the filter, and a state in which the shutter opens the second opening. A second mode of sucking the air in the image forming apparatus to the duct, and a control unit that controls the opening and closing of the shutter to execute
The image forming apparatus, wherein the filter is provided so as to face the conveyance path, and the second opening is provided at a side surface of the duct that faces the fixing portion . In the continuous image formation, the control unit sucks air in the first mode until a predetermined period has elapsed from the start of image formation, and sucks air in the second mode after the predetermined period has elapsed. The image forming apparatus according to claim 1 , wherein the operation of the shutter is controlled as described above. The filter is an image forming apparatus according to claim 1 or claim 2, characterized in that a plate-shaped filter medium disposed along the longitudinal direction of the fixing section.