JP2001194981A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of performing a quick image forming on both sides of a sheet material, and with which the accuracy relating to image forming is held stably over even a long period of time of usage. SOLUTION: A copying machine 200A is equipped with a cooling fan 10 and an exhaust duct 15 in the middle of the route of a transporting path 2a, and also equipped with a cooling fan 14 and an exhaust duct 16 near a guide 12 before and under a resist. The cooling fan 10 is for performing the ventilation in the middle of the route of the circulation transporting path 2a, and the exhaust duct 15 is a fluid passage communicating with the outside of the machine for discharging the air flow sent from the cooling fan 10 to the outside of the machine. The cooling fan 14 performs ventilation to the guide 12 before and under the resist, and the exhaust duct 16 is a communicative path to the outside of the machine for discharging the air flow sent from the cooling fan 14 to the outside of the machine.

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 such as a copying machine, a printer and a facsimile machine, and more particularly to an image forming apparatus for forming an image on both sides of a sheet material.

[0002]

2. Description of the Related Art Conventionally, some image forming apparatuses such as a copying machine, a printer, and a facsimile perform image formation on both sides of a sheet material (hereinafter, simply referred to as double-sided image formation).

In such an image forming apparatus, when performing double-sided image formation on a plurality of sheet materials, the image formation is performed on only one side of the sheet material at a predetermined image formation site and then stacked on an intermediate tray. After the above operation is repeated for a plurality of sheet materials, these are successively re-conveyed to the image forming portion to form the image on the back surface.

In order to increase the productivity of double-sided image formation, a so-called stack tray in which sheets on which image formation on the first side has been completed is conveyed to image forming means on the second side by a reversing roller or the like without being stacked on an intermediate tray. Digital copiers equipped with an automatic double-sided mechanism (through-pass double-sided mechanism) have also been developed.

In the through-pass double-sided mechanism, the sheet material on which an image is formed on the first surface by the photosensitive drum at the image forming portion is reversed at the reversing section after passing through the fixing device, and passes through the through-pass both sides section (circulating transport path). Then, it is sent to the image forming site again. Then, an image is formed on the second surface by the photosensitive drum, and then passes through the fixing device again and is discharged out of the device.

[0006]

In an image forming apparatus for forming an image on both sides of a sheet material as described above, in recent years, in order to form an image on a large number of sheet materials at once, a continuous operation for a long time is required. Driving is becoming more frequent. In such a case, the sheet material that has passed the fixing device after the image formation on the first surface has been heated to about 95 ° C. due to heat during fixing. In the early stage of operation of the apparatus, the heated sheet material is naturally cooled while passing through the both-pass portion of the through-pass. Will also rise.

[0007] Such a heat transfer effect reaches the photosensitive drum, and the temperature of the photosensitive drum eventually rises to about 50 ° C. A developing container (developing device) containing a developing material is disposed near the photosensitive drum. When the developing container is overheated, the inner developing material aggregates, and normal image formation is performed. Will be gone.

The present invention has been made in view of such circumstances, and an object of the present invention is to quickly form an image on both sides of a sheet material and to use it for a long time. An object of the present invention is to provide an image forming apparatus that stably maintains the accuracy of image formation.

[0009]

In order to achieve the above object, the present invention develops a developing material in a developing unit on an image carrier and transfers the developing material to one side of a sheet material at a predetermined image forming portion. An image forming apparatus that forms an image, reverses the sheet material on which an image is formed on one side via a predetermined conveyance path without intermediate loading, re-conveys the sheet material to the image forming portion, and forms an image on the back surface. The gist of the invention is to provide a temperature rise suppressing means for suppressing a temperature rise in the developing device.

[0010] According to this configuration, since the intermediate loading of the sheet material is not performed, even in a device where continuous double-sided image formation is performed without obtaining a sufficient heat radiation opportunity, the developing material can be used. Overheating is suppressed. Therefore, aggregation of the developer is suitably suppressed, and good image formation can be maintained even when the apparatus is operated for a long time, for example.

The temperature rise suppressing means may include at least a cooling means for cooling a transport guide member provided near the developing device.

Further, the temperature rise suppressing means may include at least a cooling means for cooling the sheet material on which the image is formed on one side.

According to the above arrangement, the overheating of the developing material can be suppressed.
It is done efficiently.

[0014] Further, the temperature rise suppressing means may include a cooling fan that blows outside air outside the device into the device to perform cooling.

According to this configuration, the overheating of the developing material can be suppressed with a simple and inexpensive configuration.

Further, the cooling means for cooling the transport guide member includes a cooling fan for locally blowing and cooling the transport guide member, and an exhaust duct for discharging an air flow generated by the cooling fan to the outside of the apparatus. It may be.

The cooling means for cooling the sheet material having an image formed on one surface includes a cooling fan for locally blowing and cooling the sheet material having an image formed on one surface, and an air flow generated by the cooling fan for cooling the sheet material. It may be provided with an exhaust duct that discharges air to the air.

According to the above configuration, since the cooling fan locally cools only each cooling target member, and thereafter the airflow is discharged to the outside through the exhaust duct, the respective members are efficiently cooled. In addition, there is no possibility that an air current is generated near the photoconductor (image carrier) to disturb the image formed on the photoconductor.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the image forming apparatus of the present invention is applied to a digital copying machine will be described below with reference to FIGS.

FIG. 1 is a sectional view schematically showing the internal structure of a digital copying machine according to the present embodiment.

As shown in FIG. 1, a digital copying machine (hereinafter simply referred to as a copying machine) 100 is roughly read by an image reading section A for reading image information of a placed document, and an image reading section A. The image forming apparatus includes an image forming section B for forming an image on one side or the back side of the sheet material based on the image information, a sheet material supply section C for supplying the sheet material, and various transport paths for transporting the sheet material.

Image formation on a sheet material is performed as follows.

First, prior to image formation on a sheet material, image information of a document placed on a platen glass (not shown) of the image reading unit A is converted into an optical unit (not shown) equipped with a well-known photoelectric conversion mechanism. ).

On the other hand, the cassette 10 of the sheet material supply section C
1, 101 ′, 101 ″, or 101 ″ ″, the sheet material S is stored in the pickup rollers 102, 102 ′,
102 ″ or 102 ′ ″, and is selectively fed out by the transport rollers 103, 103 ′, 103 ″, or 1.
Vertical path (transport path) while being separated one by one by 03 '''
The sheet is conveyed to the portions of the pre-registration lower guide 12 and the pre-registration upper guide 13 through 7a. The pre-registration lower guide 12 and the pre-registration upper guide 13
2 provided so as to face each other with a predetermined gap
The sheet material S is a sheet-like member, and the conveyed sheet material S is held in a gap between the sheet materials. The registration roller 8 has a function of sending out the sheet material S positioned between the pre-registration lower guide 12 and the pre-registration upper guide 13 during image formation to the photosensitive drum 104 as an image carrier at an appropriate timing.

In the copying machine 100 of the present embodiment, the cooling fan 1 communicating with an outside air intake (not shown) near the lower guide 12 before registration and the upper guide 13 before registration.
1 is provided. The cooling fan 11 takes in the outside air (fresh air) of the copying machine and cools the registration guides 12 and 13 by appropriately blowing air in the direction of the arrow.

When forming an image on a sheet material,
Based on the image information of the document read by the optical unit on the photosensitive drum 104 whose surface is uniformly charged,
A laser beam 5a is emitted from the laser 5. This laser beam 5a is reflected by a mirror 5A, and the rotating photosensitive drum 10
4 to form an electrostatic latent image. This electrostatic latent image is transferred to the developing device 9
Drum 10 with toner (developer) supplied from
4 to visualize.

The registration roller 8 rotates in synchronization with the rotation of the photosensitive drum 104, and transfers the sheet material S sent through the vertical path 7a to the photosensitive drum 104 and the chargers 105, 1.
Send out between 06. (Transfer) Charger 105 and (Separation)
The charger 106 transfers the visible image (toner) on the photosensitive drum 104 onto the sheet material S (the transfer charger 10).
5) It has a function of separating the paper on which the visible image has been transferred from the photosensitive drum 104 (separation charger 106). The sheet material on which the visible image is transferred and separated from the photosensitive drum 104 is conveyed to a fixing device 108 by a conveyance belt 107. The fixing device 108 fixes the visible image (toner) on the sheet material S by heating the sheet material S.

According to the operation procedure described above, an image is formed on the first side (one side) of the sheet material S newly supplied from the sheet material supply section C.

When the image formation on the sheet S is completed only by the image formation on one side, the sheet S is transferred to the fixing device 1.
08 after the toner fixing process.
9 is discharged to the outside of the copying machine 100 via the flapper 110 and the discharge roller 111.

The transport roller 109 and the discharge roller 1
The flapper 110 provided in the middle of the transfer roller 112 is used to send the sheet material S sent from the transfer roller 109 to the discharge roller 111 as described above.
This is a well-known member that can appropriately switch the transport path when sending to a (described later).

Next, when a new image is formed on the back surface of the sheet material S on which the image is formed on the first surface, how the image formation is performed will be described. .

When a new image is to be formed on the back surface of the sheet material S, the flapper 110 moves the transport path along the discharge rollers 11.
By switching from the 1 side to the transport roller 112 side,
The sheet material S that has undergone the toner fixing process by the fixing device 108 is drawn into the reversing roller 1 (reversing path 1a) via the transport roller 112. The reversing roller 1 that rotates to pull the sheet material S into the reversing path 1a starts reverse rotation (reversal) after drawing the sheet material S from the leading end in the retraction direction into the reversing path 1a by a predetermined length. This reversing roller 1
, The sheet material S exits the reversing path 1a with the trailing end in the drawing direction now as the leading end in the advancing direction, and passes through the circulating conveyance path (through-pass double-sided portion) 2a provided with the conveyance rollers 2, 6 and the like. After passing through the path 7a again, before the registration roller 8, that is, the lower guide 1 before registration.
2 and a portion between the upper guide 13 before the resist. At this time, since the sheet material S has passed through the reversing path 1a, the front and back sides of the sheet material S are reversed as compared with the state before the image formation on the first surface. That is, the rear surface of the first surface is arranged to face the photosensitive roller 104.

In this manner, the image based on the new image information read by the image reading section is placed on the second surface (the back surface of the first surface) of the sheet material S in the same manner as the image formation on the first surface. To be formed. Thereafter, the sheet material S is fixed by the fixing device 108, and is then transferred to the copier 1
It is discharged outside 00.

The operation of the copier 100 when forming images on both sides of three or more sheets continuously will be described with reference to the drawings.

FIGS. 2 to 16 show that when the copying machine 100 forms a double-sided image (continuous double-sided copying) on five sheet materials S1, S2, S3, S4, and S5, each of the sheet materials changes over time. FIG. 3 is a schematic diagram showing how the processing is performed in the copying machine 100.

Here, in each figure, the sheet materials S1 to S5
The rectangular flags 1 to 10 appropriately displayed above indicate that an image is being formed on the first surface (one surface) or the second surface (back surface) of each sheet material, or that the image has been formed. This is a virtual mark attached to. Numbers 1 to 10 displayed in the flags correspond to the first to tenth formed images, respectively.

Hereinafter, the operation mode of the continuous double-sided copying by the copying machine 100 will be described with reference to items (1) to (15).

(1) First, as shown in FIG. 2, when continuous duplex copying is started, the first sheet material S1 is placed in the cassette 1
01 to the photosensitive drum 104.

(2) Next, as shown in FIG. 3, the first image is formed on one side of the first sheet material S1 at the portion of the photosensitive drum 104. On the other hand, the second sheet material S2
Is taken out of the cassette 101 and heads toward the photosensitive drum 104.

(3) As shown in FIG. 4, the first sheet material S1 that has passed through the fixing process goes to the reversing path 1a, and the third sheet material S2 is placed on one side of the second sheet material S2 at the portion of the photosensitive drum 104. An image is formed. Further, the third sheet material S3 is taken out of the cassette 101.

(4) As shown in FIG. 5, the traveling direction of the first sheet material S1 is reversed in the reversing path 1a.
The process proceeds to the fixing device 108 for the second sheet material S2 on which the third image is formed. Further, the third sheet material S3 is sent out to the photosensitive drum 104.

(5) As shown in FIG. 6, the first sheet material S1 is again transferred to the photosensitive drum 10 via the circulation conveyance path 2a.
Go to 4. Further, a fifth image is formed on one side of the third sheet S3.

(6) As shown in FIG. 7, following the first sheet material S1, the traveling direction of the second sheet material S2 is also reversed in the reversing path 1a.

(7) As shown in FIG. 8, the first sheet material S1 reaches the portion of the photosensitive drum 104, and a second image is formed on the back surface. Also, the cassette 101
A fourth sheet material S4 is newly taken out.

(8) As shown in FIG. 9, the first sheet material S1 is discharged to the outside of the copying machine 100 via the discharge roller 111 after passing through the fixing process. Further, a seventh image is formed on one side of the fourth sheet S4.

(9) As shown in FIG. 10, the discharged first sheet material S1 is placed on a discharge tray (not shown) outside the copying machine, with one surface on which the first image is formed facing downward. Is placed. Further, a fourth image is formed on the back surface of the second sheet material S2. From the cassette 101, the fifth sheet material S5 is taken out.

(10) As shown in FIG. 11, the second sheet material S2 is discharged.

(11) As shown in FIG. 12, the discharged second sheet material S1 is stacked on the first sheet S1 with one surface on which the third image is formed as the lower surface.
Further, a sixth image is formed on the back surface of the third sheet S3.

(12) As shown in FIG. 13, the fourth sheet material S4 passes through the circulating conveyance path 2a and moves toward the photosensitive drum 104 again.

(13) As shown in FIG. 14, the third sheet material S3 is discharged, and is stacked on the second sheet S2 with one surface on which the fifth image is formed as the lower surface. The eighth image is formed on the back surface of the fourth sheet S4.

(14) As shown in FIG. 15, the fourth sheet S4 is discharged, and the tenth image is formed on the back surface of the fifth sheet material S5.

(15) As shown in FIG. 16, the fourth sheet material S4 is discharged, and is stacked on the third sheet S2 with one surface on which the seventh image is formed as the lower surface. The fifth sheet material S5 is subsequently discharged.

As described above, when forming an image on both sides of a plurality of sheet materials, the sheet material having images formed on both surfaces and the image formed on only one surface (first surface) are provided over the entire sheet material conveyance path. Are alternately arranged and conveyed.

Incidentally, when images are formed on both sides of six or more sheet materials, basically, the above-described FIGS.
The new sheet material is sequentially replenished from the cassette 101 or the like in the mode described in. Then, image formation on the first surface (one surface) and image formation on the second surface (back surface) of the sheet material are alternately performed while a maximum of five sheets remain in the transport path. .

As described above, when double-sided image formation is performed on a plurality of sheet materials, the image formation on the first surface (one side) is completed, and the sheet material that has undergone the fixing process always remains in the copying machine. .

In particular, an image is formed on the first side (one side) and the sheet material that has undergone the image fixing process is temporarily stacked on an intermediate tray or the like (intermediate stacking), and then an image is formed on the second side (back side). In a copier (stack trayless type) having a configuration in which the reversal is performed on a reversing path or the like and the sheet is immediately re-conveyed to a portion of the photosensitive drum, the processing speed is remarkably increased, but the following problems are caused. Tends to occur.

That is, conventionally, in a stack trayless type copying machine, a sheet material on which an image is formed on the first side (one side) is hardly given an opportunity to be cooled after being heated in a fixing process. It had been re-conveyed to the photosensitive drum. When an image is formed on both sides of a plurality of sheet materials in such a manner, the plurality of sheet materials are constantly circulating on the transport path in a heated state. If such a state continues for a long time, the heat of the sheet material will be transmitted to each member along the transport path. Due to such heat propagation from the sheet material, the temperature of the developing material (toner) in the developing device provided particularly near the photosensitive drum rises. Since the developer tends to agglomerate at high temperatures, normal image formation on the photosensitive drum may be difficult if continuous double-sided image formation is performed for a long time using a conventional image forming apparatus. .

In this regard, in the copying machine 100 of the present embodiment, as described above, the cooling fan 11 is provided in the vicinity of the pre-registration lower guide 12 and the pre-registration upper guide 13, and this cooling fan 11 12,13
Air is blown appropriately. The pre-registration lower guide 12 and the pre-registration upper guide 13 are portions where the sheet material temporarily waits before an image is formed on the photosensitive drum, and easily absorb heat generated by the sheet material. Further, since it is usually provided near the photosensitive drum and the developing device, it is easy to transfer heat to the developing material in terms of arrangement.

Therefore, if the pre-registration lower guide 12 and the pre-registration upper guide 13 are cooled as in the present embodiment, even if the double-sided image formation on a plurality of sheets is performed for a long time, the image formation can be performed. Such accuracy can be suitably maintained.

Actually, when the double-sided image formation of a plurality of sheets was performed for a long time by the image forming apparatus without the cooling fan 11, the temperature of the lower guide before the resist was about 65 ° C., and the temperature in the developing device was about 50 ° C. Rose to the extent. On the other hand, when the image forming apparatus (copier) 100 of the present embodiment forms a double-sided image similarly for a long time, the temperature of the lower guide 13 before registration is about 35 ° C. or less, and the temperature in the developing unit 9 is about 40 ° C. It was confirmed by the inventor that the temperature was kept at or below ℃.

Since the present embodiment is embodied by a simple configuration in which a cooling fan is added near the lower guide 12 before the resist and the upper guide 13 before the resist, the internal structure of the copying machine becomes complicated and the manufacturing cost increases. It does not lead to soaring prices and is also economical.

Further, in FIG.
1 has already described that air is blown in the direction of the arrow to cool the pre-registration lower guide 12 and the pre-registration upper guide 13, but the airflow generated by the cooling fan 11 is
a, so that there is also an effect of cooling the sheet material passing therethrough.

Incidentally, the operation timing of the cooling fan 11 may be limited to only when performing double-sided image formation by a control device such as a computer, or may be always operated. Further, by adding a temperature sensor or the like, the operation may be started or stopped in accordance with the degree of temperature rise of a predetermined portion. Further, the wind power may be controlled in accordance with a preset condition. In short, the operation mode is set or controlled in advance so as to suitably suppress the heating of a member that causes a problem due to a temperature rise, such as a developing device. Configuration may be adopted.

(Second Embodiment) Next, a second embodiment in which the image forming apparatus of the present invention is applied to a digital copying machine will be described below, focusing on differences from the first embodiment. explain.

FIG. 17 is a sectional view schematically showing the internal structure of the digital copying machine according to the present embodiment.

As shown in the figure, a digital copying machine (hereinafter simply referred to as a copying machine) 200 of the present embodiment also has an image reading unit A and an image forming unit B similar to those of the first embodiment. , A sheet material supply section C, and various transport routes, and the functions and structures thereof are almost the same.
Therefore, the same reference numerals are given to the same components as those in the first embodiment, and the duplicate description will be omitted.

The copying machine 200 of the present embodiment has a cooling fan 10 and an exhaust duct 15 in the middle of the circulating transport path 2a, and further has a cooling fan 11 (FIG. Cooling fan 14)
And the exhaust duct 16,
The configuration is different from the embodiment.

The cooling fan 10 is for blowing air in the middle of the circulating conveyance path 2a.
Is a fluid passage communicating with the outside of the machine to discharge the airflow sent from the cooling fan 10 to the outside of the machine. The cooling fan 14 blows air to the pre-registration lower guide 12, and the exhaust duct 16 is a communication path to the outside of the machine for guiding the airflow sent from the cooling fan 14 to the outside of the machine.

According to such a configuration, during the copying operation of the copying machine 200, each part (the circulating transport path 2) until the sheet material heated by the fixing device 108 reaches the photosensitive drum 104 is reached.
a) and locally cooled by the resist front lower guide 12). In addition, since the airflow containing the hot air after cooling the sheet material is quickly discharged to the outside through the exhaust ducts 15 and 16, an efficient cooling action can be obtained in each part.

Further, since the wind generated by the cooling fan does not directly reach the photosensitive drum 104, the image formed on the photosensitive drum 104 does not cause even a slight disturbance.

It should be noted that various settings and control modes can be applied to the copying machine 200 of the present embodiment with respect to the operation timing of the cooling fan 11, the adjustment of the strength of the wind, and the like.
This is the same as the first embodiment.

Further, in each of the above-described embodiments, a mechanism or a structure such as a cooling fan, an outside air intake port, or exhaust dust is applied as a means for suppressing a rise in temperature. Any cooling device or other cooling device may be used.

In each of the above embodiments, the present invention is applied to a digital copying machine. However, the present invention is not limited to this, and it is possible to perform double-sided image formation on a plurality of sheet materials without intermediate stacking. For example, the present invention may be applied to any image forming apparatus including a developing material that tends to cause a problem in image formation due to a temperature rise, such as toner, a member capable of transmitting heat to the developing material, and a material. Also, effects equivalent to or equivalent to the above embodiments can be obtained.

[0074]

As described above, according to the present invention,
Even if double-sided image formation is performed continuously for a long time, the temperature in the developing device does not increase.

Therefore, suitable double-sided image formation on a large number of sheet materials is performed quickly and continuously.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an internal structure of a digital copying machine according to a first embodiment of the present invention.

FIG. 2 is an exemplary diagram illustrating an operation mode of the copying machine according to the embodiment;

FIG. 3 is an exemplary diagram illustrating an operation mode of the copying machine according to the embodiment;

FIG. 4 is an exemplary diagram illustrating an operation mode of the copying machine according to the embodiment;

FIG. 5 is an exemplary diagram explaining an operation mode of the copying machine according to the embodiment;

FIG. 6 is an exemplary diagram explaining an operation mode of the copying machine according to the embodiment;

FIG. 7 is an exemplary diagram illustrating an operation mode of the copying machine according to the embodiment;

FIG. 8 is an exemplary diagram explaining an operation mode of the copying machine according to the embodiment;

FIG. 9 is an exemplary diagram explaining an operation mode of the copying machine according to the embodiment;

FIG. 10 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment.

FIG. 11 is an exemplary diagram explaining an operation mode of the copying machine according to the embodiment;

FIG. 12 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment.

FIG. 13 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment.

FIG. 14 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment;

FIG. 15 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment.

FIG. 16 is a schematic diagram illustrating an operation mode of the copying machine according to the embodiment.

FIG. 17 is an exemplary sectional view schematically showing the internal structure of a digital copying machine according to a second embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reversing roller 1a Reversing path 2,3,4,6,103,109,112 Conveying roller 2a Circulating conveying path (both sides of a through path) 5 Laser 5A Mirror 5a Laser beam 7a Vertical path 8 Registration roller 9 Developing device 10 Cooling fan 11 Cooling fan 12 Pre-registration lower guide 13 Pre-registration upper guide 14 Cooling fan 15, 16 Exhaust duct 101 Sheet material supply cassette (cassette) 102 Pickup roller 104 Photosensitive drum 105 Transfer charger 106 Separator charger 107 Transport belt 108 Fixing device 110 Flapper 111 discharge roller

Claims (6)

[Claims] An image bearing member for developing a developing material in a developing device;
At a predetermined image forming site, an image is formed by transferring to one surface of the sheet material, and the sheet material on which the image is formed on one surface is
What is claimed is: 1. An image forming apparatus which reverses a sheet via a predetermined conveyance path without intermediate loading, re-conveys the image to a part where the image is formed, and forms an image on a back surface. An image forming apparatus comprising: 2. An image forming apparatus according to claim 1, wherein said temperature rise suppressing means has at least cooling means for cooling a conveyance guide member provided near said developing device. Forming equipment. 3. An image forming apparatus according to claim 1, wherein said temperature rise suppressing means has at least cooling means for cooling the sheet material on which one side of the image is formed. Forming equipment. 4. An image forming apparatus according to claim 1, wherein said temperature rise suppressing means includes a cooling fan for blowing outside air outside said apparatus into said apparatus to perform cooling. An image forming apparatus comprising: 5. The image forming apparatus according to claim 2, wherein said cooling means for cooling said transport guide member includes: a cooling fan for locally blowing and cooling said transport guide member; and an air flow generated by said cooling fan. An image forming apparatus comprising: an exhaust duct that discharges air to the outside. 6. The image forming apparatus according to claim 3, wherein the cooling means for cooling the sheet material having an image formed on one side thereof includes: a cooling fan for locally blowing and cooling the sheet material having an image formed on one side. An image forming apparatus, further comprising: an exhaust duct for discharging an airflow generated by the cooling fan to the outside of the apparatus.