JP2001026352A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the evaporation of water from a sheet as much as possible and to prevent a curl from being caused by the evaporation of water from the sheet. SOLUTION: A route R for ejecting papers is prepared between a fixing device 36 which heats a toner image formed in an image forming device and transcribed on a sheet P and fixes on the sheet and a paper discharge port 37 to discharge the sheet P outside. A vapor keeping space 20 to keep vapor generated from the sheet P which is heated in the fixing device 36 is formed at least in the end part of the fixing device side on the route R for discharging papers. The sheet P is forced to pass this vapor keeping space 20 after it passes through the fixing device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a fixing device, and more particularly to a device for preventing a sheet from curling due to heating when a toner image is fixed in the fixing device.

[0002]

2. Description of the Related Art Conventional image forming apparatuses such as printers, copiers, facsimile machines, multifunction printers, etc. are formed in an image forming section by an appropriate image forming means such as an electrophotographic system, an electrostatic recording system, and a magnetic recording system. After the transferred toner image is transferred to a sheet, the toner image is heated by a fixing device and fixed to the sheet.

FIG. 12 is a view showing the structure of a conventional fixing device provided in such an image forming apparatus. In FIG. 12, reference numeral 100 denotes a fixing device.
Reference numeral 00 denotes a film fixing device 101, which is a heating device in which a heat-resistant cylindrical film 101b is rotatably arranged on the outer periphery of a ceramic heater 101a;
And a pressure roller 102 for conveying the sheet under pressure.

Further, reference numerals 103 and 104 denote a conveying upper guide and a conveying lower guide which form a paper discharge path R for guiding a sheet (not shown) to a paper discharge port 105a, 105 a paper discharge roller for discharging the sheet from the paper discharge port 105a, Reference numeral 106 denotes a paper discharge roller pressed against the paper discharge roller 105 by a roller spring (not shown);
Reference numeral 07 denotes a fixing device cover, reference numeral 108 denotes a roller cover, and reference numeral 109 denotes a sheet discharge stacking unit for stacking sheets discharged from the sheet discharge port 105a.

[0005] Further, reference numeral 110 denotes an exterior cover. The exterior cover 110 discharges heat and water vapor generated from the sheet heated by the fixing device 100 to the outside of the apparatus.
An exhaust port 111 having a shape as shown in FIG.

In order to direct the heat and steam generated from the sheet to the exhaust port 111, for example,
14 is provided with a plurality of ribs 103a extending in the vertical direction as shown in FIG. 14, along which the steam flows in the direction of the arrow and flows toward the exhaust port 111. In addition, such a rib is provided in the lower conveyance guide 10.
4 is also provided.

After the toner image is transferred in the image forming apparatus configured as described above, the sheet is firstly subjected to the film fixing device 101 and the pressure roller 1 shown in FIG.
In the fixing nip portion N formed by the fixing member N2, heat and pressure are applied to the fixing nip portion N, and an unfixed image is fixed on the sheet.

Next, the sheet on which the image is fixed in this way passes through the fixing nip portion N, is guided by the upper conveyance guide 103 and the lower conveyance guide 104, and is cooled and dried on the way to the discharge roller 105. Then, the discharge roller 105 and the discharge roller 106 cause the discharge stacking section 10
9 is conveyed and discharged.

By the way, after passing through the fixing nip N in this way, until the sheet is conveyed and discharged to the sheet discharge stacking section 109,
Water evaporates from the sheet heated at the fixing nip portion N, and the water vapor passes between the ribs 103a provided on the upper conveyance guide 103 and the lower conveyance guide 104 and passes through the exhaust port 1
It diverges out of the plane from 11.

[0010]

However, in such a conventional image forming apparatus, when the sheet is cooled after the temperature is increased at the fixing nip portion N and the moisture is lost, the sheet is curled. There was a problem.

Therefore, conventionally, in order to suppress the occurrence of such curling, for example, a contrivance for giving moisture to the sheet in the middle of paper discharge, as a specific example, as disclosed in Japanese Patent Application Laid-Open No. 4-291277, is disclosed. Attempts have been made not to let the water vapor escape to the outside of the machine, but to close the paper discharge port to store water vapor near the paper discharge port and return moisture to the sheet when the sheet is discharged. .

However, even when such a configuration is employed, the moisture evaporates once when the sheet is at the highest temperature after passing through the fixing nip, so that water vapor is stored near the discharge port and the sheet is re-absorbed. Even if such an attempt was made, sufficient moisture could not be given to the sheet, and the effect of suppressing curling was not sufficient.

Accordingly, the present invention has been made in view of such circumstances, and an image capable of suppressing evaporation of moisture from a sheet as much as possible and preventing curling caused by evaporation of moisture from the sheet. It is an object to provide a forming apparatus.

[0014]

According to the present invention, after a toner image formed in an image forming section is transferred to a sheet, the toner image is heated by a fixing device and fixed to the sheet.
Thereafter, in the image forming apparatus configured to discharge the sheet from the discharge port, at least an end of the discharge path provided between the fixing device and the discharge port on the fixing device side is provided. A steam retention space for retaining steam generated from the sheet heated by the fixing device is formed.

Further, the present invention is characterized in that a gradient is formed at an end of the upper guide member forming the upper surface of the sheet conveying path on the fixing device side so that the downstream side is lower than the upstream side in the sheet conveying direction. Things.

Further, the invention is characterized in that the sheet after passing through the fixing device is conveyed downward.

Further, the present invention is characterized in that the fixing device side end of the sheet conveying path is curved downward so as to convey the sheet having passed through the fixing device downward.

Further, the present invention is characterized in that a downstream conveying means for conveying the sheet after passing through the fixing device downward is provided downstream of the fixing device.

Further, the present invention is characterized in that a portion from the fixing device to an outlet of the water vapor retaining space of the paper discharge passage is substantially sealed.

Further, the present invention is characterized in that a conveying means for conveying a sheet to the paper discharge port is provided at an outlet of the water vapor retaining space, and the outlet of the water vapor retaining space is closed by the conveying means. .

Further, the present invention is characterized in that the paper discharge passage is entirely a water vapor retention space, and the paper discharge port, which is an outlet of the water vapor retention space, is closed in a state in which sheets can be discharged. Is what you do.

Further, the present invention is characterized in that the discharge port is closed by a discharge means provided at the discharge port for discharging the sheet.

Further, according to the present invention, the fixing device includes a heating device and a pressure roller located at an entrance of the water vapor retention space, and the heating device and the pressure roller, which substantially seal the water vapor retention space, A gap between the heating device and a peripheral member disposed around the pressure roller and constituting an entrance of the steam retention space is closed by a closing member.

Further, the present invention is characterized in that a cleaning member for cleaning the surfaces of the heating device and the pressure roller is used as the closing member.

Further, as in the present invention, between the fixing device for heating the toner image formed in the image forming section and transferred to the sheet to fix the toner image on the sheet, and the paper discharge port for discharging the sheet to the outside. In addition to providing a paper discharge passage, a water vapor retention space for retaining water vapor generated from the sheet heated by the fixing device is formed at least at an end of the paper discharge passage on the fixing device side. The sheet after passing through the device is passed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a laser beam printer which is an example of an image forming apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 30 denotes a laser beam printer, 31 denotes a laser beam printer main body (hereinafter referred to as a main body), and 32 denotes a laser scanner unit, for example, a laser beam based on image data from a host computer (not shown). Is raster-scanned, and a folding mirror 34 forms an electrostatic latent image on the photosensitive drum 33b which is charged in advance by the charger 33a.

The electrostatic latent image formed on the photosensitive drum 33b is developed by the developing unit 33c with toner, and then transferred to the transfer unit 3.
In 3d, the image is transferred onto a sheet (not shown) conveyed by the conveying roller pair 35.

Thereafter, the toner image transferred onto the sheet is fixed to the sheet by the fixing device 36, and the sheet on which the toner image is fixed is further fixed to the fixing device 36.
Is passed through the paper discharge roller 5 as a paper discharge means provided at the paper discharge port 37 and a roller spring (not shown).
The paper is discharged to the paper discharge stacking section 9 provided on the upper surface of the main body 31 by the paper discharge roller 6 pressed to the side.

As shown in FIG. 2, the fixing device 36 includes a film fixing device, which is a heating device in which a heat-resistant cylindrical film 1b is rotatably arranged around a ceramic heater 1a, and a pair with the film fixing device 1. And a pressure roller 2 for pressing and conveying the formed sheet. Note that 7,
Reference numeral 8 denotes a fixing device cover and a roller cover which form a part of the housing of the fixing device 36. Reference numeral 10 denotes a housing of the main body 31.

On the other hand, in FIG.
An upper conveyance guide and a lower conveyance guide that form a paper discharge path R that guides the sheet that has passed through the sheet 6 to the paper discharge port 37. Reference numeral 20 is formed at least at an end of the paper discharge path R on the fixing device side. A steam retention space for retaining steam generated from the sheet heated at 36.

By providing the water vapor retention space 20 at least at the end of the paper discharge passage R on the side of the fixing device, the sheet heated at the fixing nip N and heated to a high temperature immediately after the fixing nip N Then, the water passes through the high-humidity water vapor retention space in which the water vapor is retained, and is conveyed while being cooled.

When the sheet is conveyed while being cooled, the amount of water escaping into the atmosphere can be suppressed even when the sheet is heated to a high temperature in the fixing nip portion N. Can be prevented from being curled due to the loss of.

Next, the fixing operation and the sheet discharging operation of the laser beam printer having the above configuration will be described.

After the transfer of the toner image, the sheet is first subjected to a film fixing device 1 and a pressure roller 2 as shown in FIG.
Into the fixing nip N formed by the heating and pressing at the fixing nip N, the unfixed image is
Is established.

Next, the sheet P on which the image has been fixed in this way passes through the fixing nip portion N, and is guided by the upper transport guide 3 and the lower transport guide 4 to the discharge roller 5 while being cooled, Thereafter, the sheet is conveyed and discharged to the discharge stacking section 9 by the discharge roller 5 and the discharge roller 6.

Here, after passing through the fixing nip N, water vapor and heat are radiated from the sheet P heated in the fixing nip N. Since the water passes through the stay space, the evaporation of water is suppressed, and the temperature decreases.

The water vapor retention space 20 is provided immediately after the fixing device 36, and the sheet P heated in the fixing nip portion N is passed through the water vapor retention space 20 to evaporate moisture from the sheet P. And the temperature of the sheet can be reduced while suppressing the occurrence of heat. As a result, a change in the amount of water before and after heat fixing can be suppressed to be small, and curling of the sheet can be suppressed.

In the present embodiment, the end of the upper conveying member 3, which is the upper guide member, on the fixing device side is
A gradient is formed such that the downstream side is lower than the upstream side in the sheet conveyance direction.

Then, such a gradient is applied to the transport guide 3.
As a result, the water vapor generated from the sheet during the conveyance moves toward the fixing device due to the gradient of the upper conveyance guide 3 as shown by the arrow in FIG. The moisture in the water vapor stagnation space 20 immediately after the fixing nip where the water is easily evaporated increases, and the evaporation of moisture from the sheet P can be suppressed more effectively.

Further, in the present embodiment, the upper conveying guide 3 forms a water vapor retaining space 20 which is substantially closed by the lower conveying guide 4 and a wall (not shown) existing in the front-rear direction of the drawing. . Then, by sealing the water vapor retention space 20 in this manner, the water vapor retention space 2
The humidity of 0 can be kept higher, whereby the evaporation of moisture from the sheet P can be suppressed more reliably.

FIG. 4 shows a case where the film fixing device 1 which is the heating device in FIG. 2 is replaced by a heat roller fixing device 11, but even in such a configuration, the film fixing device described with reference to FIGS. The same effect as described above can be obtained. Further, in this embodiment, the upper conveyance guide 3 and the fixing device cover 7 and the lower conveyance guide 4 and the roller cover 8 are formed separately, but may be formed integrally.

Next, a second embodiment of the present invention will be described.

FIG. 5 is a diagram for explaining the configuration near the fixing device of the image forming apparatus according to the present embodiment. 2, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In the figure, reference numerals 13 and 14 denote an upper conveyance guide and a lower conveyance guide which form a paper discharge path R. The fixing device side ends of the upper conveyance guide 13 and the lower conveyance guide 14 are curved downward. I have.

Then, the ends of the upper conveyance guide 13 and the lower conveyance guide 14 are curved downward, and the discharge path R
By bending the fixing device side end portion downward, the sheet that has passed through the fixing device can be conveyed downward from when the sheet passes through the fixing device 36. This allows
Water vapor generated from the lower surface of the sheet heated by passing through the fixing nip portion N can be guided to the fixing device side by the sheet.

Next, the fixing operation and the sheet discharging operation of the image forming apparatus thus configured will be described.

After the transfer of the toner image, the sheet is first subjected to a film fixing device 1 and a pressure roller 2 as shown in FIG.
Into the fixing nip N formed by the heating and pressing at the fixing nip N, the unfixed image is
Established in

Next, the sheet P on which the image is fixed in this way passes through the fixing nip portion N, and is guided by the upper conveying guide 13 and the lower conveying guide 14 to the discharge roller 5 while being cooled, Thereafter, the sheet is conveyed and discharged to the discharge stacking section 9 by the discharge roller 5 and the discharge roller 6.

Here, after passing through the fixing nip N, water vapor and heat are radiated from the sheet P heated in the fixing nip N. Since the water passes through the stay space, the evaporation of water is suppressed, and the temperature decreases.

The water vapor generated from the sheet P during the conveyance is moved downward along the sheet P to the fixing device side as shown in FIG. The moisture in the water vapor retention space 20 immediately after the fixing nip where the temperature becomes high and the moisture evaporates most easily becomes high, and the evaporation of the moisture from the sheet can be suppressed more effectively.

In the present embodiment, the end of the paper discharge passage R on the fixing device side is curved downward in order to guide the sheet downward. However, the present embodiment is not limited to this. The same applies to a case where a pair of conveying rollers is installed as an example of a lower conveying unit immediately after the portion N, and the sheet after passing through the fixing nip portion N is guided below the fixing nip portion N by the pair of conveying rollers. It is clear that the effect can be obtained.

Next, a third embodiment of the present invention will be described.

FIG. 7 is a diagram showing a configuration near the fixing device of the image forming apparatus according to the present embodiment. 2, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In the drawing, reference numeral 15 denotes a paper discharge roller, 16 denotes paper discharge rollers 15a and 16a which are in pressure contact with the paper discharge roller 15, and these paper discharge rollers 15 and 16
Has a uniform outer diameter in the sheet width direction as shown in FIG. 8, and has a length equal to or longer than the width of the paper discharge port 37.

Then, the discharge roller 15 and the discharge roller 16
With such a configuration, the discharge port 37 can be closed with a simple configuration in a state where the sheet can be discharged, and thereby, from the downstream side of the steam retention space 20 in the sheet conveyance direction, that is, The release of water vapor from the paper discharge port 37 can be prevented, and the water vapor retention space 2 just before the paper discharge port can be prevented.
0 can be made. As a result, a change in the amount of water between before and after heat fixing can be further reduced, and curling of the sheet can be suppressed.

In FIG. 7, reference numeral 17 denotes a film fixing device 1 and a fixing device cover 7, a pressure roller 2 and a roller cover 8;
This is a pad that is a closing member that closes a gap between the pad. And, as described above, the water vapor retention space 20 is formed by the pad 17.
Fixing device 1 and pressure roller 2 located at the entrance of
And a cover 7, 8 which is an example of a peripheral member disposed around the film fixing device 1 and the pressure roller 2 and constituting the entrance of the water vapor retention space 20, thereby closing the gap.
The steam retention space 20 can be substantially sealed. Further, this makes it possible to prevent the water vapor in the water vapor retention space from escaping, and to keep the water vapor retention space 20 at high humidity.

Incidentally, a roller cleaning member for cleaning the surface, which is provided on the film fixing device 1 and the pressure roller 2, may be used as the pad 17. By using such a roller cleaning member, conventional parts can be used. It becomes possible to take a closed structure while leaving.

Further, in the present embodiment, the covers 7 and 8 are described as an example of the peripheral members constituting the entrance of the water vapor retention space 20, but the entrance of the water vapor retention space 20 is provided in the main body 31, for example. In the case of using a member such as a rib, a gap between the member such as a rib and the film fixing device 1 and the pressure roller 2 is closed by a closing member.

Next, the fixing operation and the sheet discharging operation of the image forming apparatus thus configured will be described.

After the toner image is transferred, the sheet first enters a fixing nip portion N formed by the film fixing device 1 and the pressure roller 2, and is heated and pressed at the fixing nip portion N, so that an unfixed image is formed. Fixes to sheet.

Next, the sheet P on which the image has been fixed in this way passes through the fixing nip portion N, and is guided by the upper conveyance guide 3 and the lower conveyance guide 4 to the discharge roller 5 while being cooled, Thereafter, the sheet is conveyed and discharged to the discharge stacking section 9 by the discharge roller 15 and the discharge roller 16.

Here, when the sheet P passes through the fixing nip N, water vapor and heat are radiated from the sheet P heated in the fixing nip N. Since the water passes through the stay space, the evaporation of water is suppressed, and the temperature decreases.

Since the front and rear ends of the water vapor retention space 20 in the paper transport direction are closed by the pad 17, the paper discharge roller 15 and the paper discharge roller 16, the water vapor generated from the sheet during transportation is retained in the water vapor retention space 20. As a result, the vicinity of the exit of the fixing nip becomes even more humid. As a result, evaporation of moisture from the sheet can be more effectively suppressed, and curling of the sheet can be suppressed.

As described above, the vicinity of the paper discharge port and the vicinity of the fixing nip portion are substantially closed, and the space from the fixing device 36 to the outlet of the water vapor retention space 20 of the paper discharge passage R is substantially sealed.
The humidity in the water vapor retention space 20 can be reliably kept high over the entire area, whereby the diffusion of moisture from the sheet P can be suppressed, and the curl of the sheet can be suppressed.

By the way, the case where the discharge roller 15 and the discharge roller 16 having a uniform outer diameter in the sheet width direction are provided in the discharge port 37 so as to close the outlet of the steam retention space 20 has been described. The embodiment is not limited to this,
For example, as shown in FIG. 9, between the fixing device 36 and the paper discharge port 37, the transport roller 17 and the transport roller 1 having the same configuration as the paper discharge roller 15 and the paper discharge roller 16 used in FIGS.
8 may be provided, and the steam retention space 20 may be closed by the transport rollers 17 and the transport rollers 18.

Here, the steam retaining space 20 is substantially sealed by the transport roller 17 and the transport roller 18 as described above, and the steam retaining space 20 from immediately after the fixing nip portion of the paper discharge passage R to the transport roller 17 and the transport roller 18 is formed. It can be used and the subsequent paper discharge path R can be opened.
By opening the paper discharge passage R after the water vapor retention space in this way, heat and water vapor from the sheet can be discharged to the outside from the exhaust port 11 provided in the housing 10 of the main body 31.

On the other hand, the case where the discharge port 37 is closed by the discharge roller 15 and the discharge roller 16 has been described above, but the present embodiment is not limited to this, and the discharge roller 5 is not limited to this.
10 and 11 when the plurality of paper discharge rollers 6 are attached to the respective shafts 5a, 6a at predetermined intervals.
A rib 10a may be provided at the upper and lower edges of the paper discharge port 37 to close the gap between the adjacent paper discharge rollers 5 and the paper discharge rollers 6 so that the sheet can be discharged.

Further, if the discharge port 37 is substantially closed by using another member such as a film instead of the rib 10a, the same effect can be obtained more easily.

[0071]

As described above, according to the present invention, the sheet heated by the fixing device is provided at least at the end of the sheet discharging path provided between the fixing device and the sheet discharging port on the fixing device side. By forming a water vapor retention space for retaining water vapor generated from the sheet, and by allowing the sheet after passing through the fixing device to pass through this water vapor retention space, evaporation of moisture from the sheet can be suppressed as much as possible, Curling caused by evaporation of water can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of a fixing device of the laser beam printer.

FIG. 3 is a diagram illustrating the flow of water vapor from the upper surface of a sheet after passing through the fixing device.

FIG. 4 is a diagram showing another configuration of the laser beam printer according to the first embodiment.

FIG. 5 is a diagram illustrating a configuration near a fixing device of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating the flow of water vapor from the lower surface of a sheet after passing through a fixing device of the image forming apparatus.

FIG. 7 is a diagram illustrating a configuration near a fixing device of an image forming apparatus according to a third embodiment of the present invention.

FIG. 8 is a perspective view of a discharge roller and a discharge roller of the image forming apparatus.

FIG. 9 is a diagram illustrating another configuration near the fixing device.

FIG. 10 is a diagram illustrating another configuration near the fixing device.

FIG. 11 is a perspective view of the vicinity of a paper discharge port of the image forming apparatus according to the other configuration.

FIG. 12 is a diagram illustrating a configuration near a fixing device of a conventional image forming apparatus.

FIG. 13 is a perspective view showing an exhaust port of a conventional image forming apparatus.

FIG. 14 is a perspective view of an upper conveyance guide of a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 film fixing device 2 pressure roller 3, 13 upper conveyance guide 4, 14 lower conveyance guide 5, 15 discharge roller 6, 16 discharge roller 9 discharge stacking unit 10 housing 17 pad 20 water vapor retention space 30 laser beam printer 36 fixing device 37 paper discharge port P sheet R paper discharge path

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA15 AA39 BA10 BA12 BA48 BB01 BB28 3F053 HA03 HB00 LA02 LA05 LA07 LB01

Claims (11)

[Claims] An image forming section transfers a toner image formed on the sheet to a sheet, and then heats the toner image by a fixing device to fix the sheet on the sheet. Thereafter, the sheet is discharged from a sheet discharge port. In the image forming apparatus according to the first aspect of the present invention, a sheet generated from the sheet heated by the fixing device is provided at least at an end of the sheet discharge passage provided between the fixing device and the sheet discharge port on the fixing device side. An image forming apparatus having a water vapor retaining space for retaining water vapor. 2. The image forming apparatus according to claim 1, wherein a gradient is formed at an end of the upper guide member forming the upper surface of the sheet conveying path on the fixing device side so that the downstream side is lower than the upstream side in the sheet conveying direction. The image forming apparatus as described in the above. 3. The apparatus according to claim 1, wherein the sheet after passing through the fixing device is conveyed downward.
The image forming apparatus as described in the above. 4. The image forming apparatus according to claim 3, wherein an end of the sheet conveying path on the fixing device side is curved downward so as to convey the sheet having passed through the fixing device downward. 5. The image forming apparatus according to claim 3, further comprising a lower conveying unit that conveys the sheet after passing through the fixing device downward, downstream of the fixing device. 6. The image forming apparatus according to claim 1, wherein a portion from the fixing device to an outlet of the water vapor retention space of the paper discharge passage is substantially sealed. 7. An image according to claim 6, wherein a conveying means for conveying a sheet to said paper discharge port is provided at an outlet of said water vapor retaining space, and said conveying means closes an outlet of said water vapor retaining space. Forming equipment. 8. The apparatus according to claim 1, wherein the paper discharge passage is entirely a water vapor retention space, and the paper discharge port, which is an outlet of the water vapor retention space, is closed in a state where sheets can be discharged. 7. The image forming apparatus according to any one of 1 to 6. 9. The image forming apparatus according to claim 8, wherein the discharge port is closed by a discharge unit provided in the discharge port for discharging the sheet. 10. The fixing device includes a heating device and a pressure roller positioned at an entrance of the water vapor retention space, the heating device and the pressure roller substantially sealing the water vapor retention space, the heating device and the pressure device. Placed around the pressure roller,
The image forming apparatus according to any one of claims 1 to 9, wherein a gap between the water vapor retention space and a peripheral member constituting an entrance of the water vapor retention space is closed by a closing member. 11. The image forming apparatus according to claim 10, wherein a cleaning member that cleans surfaces of the heating device and the pressure roller is used as the closing member.