JP2000351478A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a surface of a carrying passage hard to be electrified, and to restrain abrasion by a transfer material by covering a surface of the carrying passage slidingly rubbing with the unprinted surface side or one printing surface side of the transfer material with a low frinction resin. SOLUTION: A surface of a carrying passage slidingly rubbing with the unprinted surface side or one printing surface side of a transfer material is covered with a low friction resin. For example, in a carrying guide having a resin carrying guide 103 molded by an ABS resin, a material applied with an adhesive to a sheet 104 of a fluororesin having a surface having an adhesive surface of polytetrafluoroethylene is bent with the rib apex as the center to be adhered to a side surface of a rib. Thus, a low frictional carrying rib can be obtained to a transfer material by forming a thin film fluororesin layer having a thickness of about 20 to 200 μm on a rib surface to thereby eliminate the occurrence of image scattering as well as to reduce an abrasion quantity.

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 used for an electrophotographic printer, a copying machine, and the like.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic system has been widely used as an image forming method for forming an image on a recording material. The general method is to form an electric latent image by performing charging and exposure on a photoreceptor using a photoconductive material, and develop this latent image with a colored toner to visualize the latent image. Things.

The toner image developed on the photoreceptor is electrically attracted from the back side of the transfer material conveyed at a predetermined timing by corona discharge or bias applying means such as an elastic roller. Thereafter, the transfer material is separated from the surface of the photoreceptor by a curvature of the photoreceptor and a static eliminator provided near the transfer bias applying unit, and is guided to a transport path. Further, the transfer material is conveyed to a fixing device, where the transfer material is heated and pressed to fuse and fix the toner to obtain a fixed image.

In such an image forming apparatus, the transport path for transporting the transfer material separated from the photoreceptor is as follows.

[0005] 1) As shown in FIG. 9, for example, a rib 11 made of a resin molded member such as ABS having a rib on the surface and a transport guide 10 made of a sheet metal member 12 made of gin-coated steel or the like
There is. The sheet metal member 12 has an action of adsorbing the transferred transfer material, and transfers the transfer material separated from the photoreceptor to the rib 11.
Can be stably held on The rib 11 has a role of reducing the frictional resistance between the transfer material and the conveyance guide 10 and smoothing the conveyance to the fixing device.

When the transfer is performed, the transfer material is charged by applying a transfer bias from the back side of the printing surface. However, the transfer material is appropriately neutralized by applying a bias having a polarity opposite to that of the transfer bias by a static elimination means such as a static elimination needle. You. Without extermination,
Not only does the rubbing resistance between the transfer material and the transport guide increase, but the charge on the transfer material leaks into the transport guide, causing a sudden change in the electric field to disturb the surrounding toner image. I do. Conversely, if the charge of the transfer material is excessively removed, the toner holding power on the transfer material will be lost, causing “tailing” and “offset” phenomena in the fixing device, or the transfer material and sheet metal in long paper. The attraction force of the members is weakened, and the paper floats up and comes into contact with the surrounding members, disturbing the image. Therefore, it is necessary to appropriately remove the charge on the transfer material.

2) Also, instead of the ribs of the transport guide,
As shown in FIG. 11, there is a type in which a plurality of resin-made conveying rollers 48 are arranged in the vicinity of the photoconductor 1. The transport roller 48 is rotatably disposed to regulate the separation direction (separation angle) of the transfer material separated and removed from the photosensitive member 1 by a bias applied to the charge removing needle 8. By regulating the direction in which the transfer material is separated, the separation discharge between the transfer material and the photoreceptor is reduced, and there is an effect of suppressing the occurrence of image defects due to the separation discharge.

The above-described method of using the ribs and rollers for the conveyance guide has an advantage that the structure is simple and can be manufactured at a low cost. However, the distance between the transfer device and the fixing device is at least the distance of the minimum size used. Must be set. When the distance between the transfer device and the fixing device is reduced, accuracy in matching the peripheral speeds of the transfer device and the fixing device is required to suppress slack in long paper. In addition, the fixing device, which is a heat source, needs to be close to the cleaning container, and thus the possibility of toner blocking increases.

[0009] 3) As another transport path, there is an endless belt whose surface is formed of a resin or rubber material having frictional force as shown in FIG. This is because the surface of the belt is charged by a charger 50 disposed on the inner surface or the outer surface of the endless belt to adsorb the transfer material onto the belt surface. Immediately before the entrance of the fixing device, the charge is removed by a charger 51 for separation. Guide member for promotion (hereinafter referred to as fixing entrance guide)
Is used to convey to the entrance of the fixing device.

If the endless belt 49 is used, the distance between the transfer device and the fixing device can be set irrespective of the paper size to be used. However, a belt driving member and a charging member are required, and the cost is higher than that of the transport guide. Become. If the transfer device is a transfer roller, it is necessary to match the peripheral speed between the transfer roller and the endless belt and between the endless belt and the fixing device.

[0011]

The image forming apparatus using the above-mentioned conventional conveying path has the following problems. 1) When a transport guide is used, for example, the ribs made of ABS resin and paper are rubbed and charged, and the unfixed toner image on the transfer material corresponding to the ribs is disturbed, which may cause "image scattering". This phenomenon is caused by weighing 60-90 g / m ² , paper resistance 10
^This is likely to occur when paper with a relatively high resistance of ¹² Ω or more is continuously passed. Further, when an automatic double-sided device is provided, this phenomenon is particularly noticeable when printing on the second side where the paper has increased resistance after passing through the fixing device, or when used in a low humidity environment.

In order to avoid this phenomenon, a surface active agent may be added or a metal oxide may be dispersed to make the surface hard to be charged in order to adjust the resin molded member to be conductive or semiconductive. However, the releasability of the surface is reduced, or the surfactant is deposited on the surface, thereby lowering the resistance and causing a “polka dot” phenomenon. Further, those coated with a conductive or semi-conductive paint have a weak coating film strength, and peel off from the surface when the number of paper passing increases.

As described in 2) above, when a plurality of resin-made rollers are arranged in the transport path, a polyacetal resin or the like having excellent wear resistance is used for the transport rollers. Or a filler of the transfer material adheres, and the transfer material is strongly charged, thereby causing "image scattering".

Even when an endless belt as described in 3) above is used, since the fixing entrance guide is strongly rubbed when the transfer material is peeled off from the endless belt, a similar slidable charge is generated at the fixing entrance guide. Wake up and "image scattering" occurs.

2) Further, the space between the transfer device and the fixing device is
In an image forming apparatus including a conveyance guide and a fixing entrance guide, when the number of sheets passing exceeds several hundred thousand, the rib surface is gradually worn by the transfer material, and the contact area with the transfer material increases. As a result, before the transfer material is transported to the fixing device,
An electrostatic brake is applied to the transfer material, the transfer material ramps up in the middle of conveyance, and the transfer member comes into contact with surrounding members, resulting in an image failure. It often happens.

The above phenomena are all caused by the fact that the surface of the rib is strongly charged by the transfer of the transfer material, and that the rib is worn and the contact area is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a transport path for transporting a transfer material to a fixing device while supporting the non-printing surface side, thereby making it difficult to charge the surface of the transport path and reducing abrasion due to the transfer material. An object of the present invention is to provide an image forming apparatus in which the number is reduced.

[0018]

The above object is achieved by the following means.

That is, the present invention relates to an image forming apparatus for transferring a toner image on an image carrier onto a transfer material by applying a bias from behind the transfer material and conveying the transfer material to a fixing device. A non-printing surface side or one of the printing surface sides of the conveyance path on which the surface of the conveyance path is rubbed is coated with a low friction resin, and a low friction resin covering the surface of the conveyance path is proposed. Is a fluororesin layer, the fluororesin layer covering the surface of the transport path is a polytetrafluoroethylene resin layer, and the fluororesin layer covering the surface of the transport path is tetrafluorocarbon having -CF ₃ in a terminal group. Being a fluoroethylene-perfluoroalkyl vinyl ether copolymer resin layer, the fluororesin layer covering the surface of the transport path has a surface resistance value of 10 ⁸ to 10 ¹² Ω, and when performing double-sided printing, , An automatic double-sided device that automatically conveys the printed images on the first and second surfaces to the fixing device through the same conveyance path; the conveyance path includes fixed ribs, rotatable rollers, and a fixing inlet; It includes one of the guides or a combination of some of them.

According to the present invention, in an image forming apparatus for transferring a toner image on an image bearing member onto a transfer material by applying a bias from behind the transfer material and conveying the transfer material to a fixing device, This is achieved by coating the surface of the transport path on which the non-printing surface side or one of the printing surface sides rubs with a low friction resin.

When the surface of the transport path is covered with a fluororesin layer, the abrasion resistance is excellent and it is particularly effective. If the fluororesin is polytetrafluoroethylene (PTFE) resin, the rubbing resistance of the transfer material is particularly small. In addition, P consisting of --CF ₃
In the case of using an FA resin layer, the surface of the conveyance path is hardly charged, and a better effect can be obtained.

Further, a conductive material may be dispersed in a fluororesin to have a surface resistance of 10 ⁸ to 10 ¹² Ω.

The image forming apparatus of the present invention works effectively even in an image forming apparatus having an automatic double-sided device in which "image scattering" easily occurs.

The transport path may be constituted by one of a fixed rib, a rotatable roller, and a fixing entrance guide, or may be constituted by combining some of them.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

The image forming process in the image forming apparatus according to the present invention will be described with reference to FIG. 10. First, the surface of the photosensitive drum 1 installed substantially at the center of the apparatus is uniformly charged by the primary charger 29, and the An image exposure is performed by 28 to form an electrostatic latent image on the surface of the photosensitive drum 1. This electrostatic latent image is developed by the developing device 30 and visualized as a toner image.

The paper 19 is taken out of the paper cassette 36 by the paper feed roller 25 in synchronization with the image formation on the photosensitive drum 1, and
The sheet is conveyed to the registration roller pair 31 via the conveyance guide 34, the conveyance roller 33, and the conveyance guide 32. The registration roller pair 31 rotates in synchronization with the image on the photosensitive drum 1 and conveys the paper 19 to the transfer nip formed by the photosensitive drum 1 and the transfer roller 4 via the transfer guide 14. Photosensitive drum 1
The toner image formed thereon is transferred onto the paper 19 at the transfer nip.

The paper 19 on which the transfer has been completed is separated from the photosensitive drum 1 by the action of the curvature separation by the small diameter drum and the electrostatic separation by the static elimination needle 8. A voltage having a polarity opposite to that of the transfer bias is applied to the static elimination needle 8 by a bias power supply (not shown). The paper 19 separated from the photosensitive drum 1 is transported to the fixing device 13 via the transport guide 10, where the unfixed toner image as transferred is fixed to form a fixed image. In the case of single-sided printing, the paper 19 is sent to the transport guide 38 by the flapper 37 and is discharged by the discharge roller 43.

On the other hand, in the case of double-sided printing, the paper 19 on which fixing has been completed is conveyed to the conveyance guide 39 by the flapper 37, and once conveyed by the conveyance roller 40 in the direction of the conveyance guide 41, and then the reverse of the conveyance roller 40. By rotation, paper 19
Is transported in the direction of the transport guide. In this process, paper 1
9 is reversed.

The paper 19, which has been turned upside down, is transported by the transport rollers 4.
3. The transfer process is performed again via the transport guide 44. 2
The paper 19 on which the second transfer and fixing steps have been completed is flapper 3
The sheet is conveyed upward by the sheet feeder 7, and is discharged to a sheet discharge tray 46 via a transfer guide 38 and a sheet discharge roller 45. Reference numeral 47 denotes an exterior that protects and protects the inside of the device.

[0031]

The present invention will be further described below with reference to examples and comparative examples.

Example 1 and Comparative Examples 1-2 The transfer path between transfer and fixing used in this example will be described in detail.

The voltage applied to the static elimination needle 110 shown in FIG.
The paper 19, which is a transfer material, is separated from the photosensitive drum 1 by a bias of 2 kV and guided to the transport guide of the present embodiment. Even after the leading end of the paper is separated from the photosensitive drum 1, a bias of -1 kV is applied to the static elimination needle 110 to appropriately remove the electric charge on the back of the paper and to prevent the generation of "polka dots" due to the leakage of the electric charge on the paper. Then, the paper is attracted to the ribs of the transport guide to perform stable transport. Here, the transport guide is formed by using a metal sheet as a base and forming a fluororesin layer thereon to reduce the frictional resistance of the rib surface. That is, conventional AB
A thin fluororesin layer could not be formed on the ribs molded of S resin because the melting point of the fluororesin was as high as 280 ° C or higher. However, PTFE resin, PFA resin (tetra Fluororesin powder such as fluoroethylene-perfluoroalkylvinyl ether copolymer) is applied to a metal sheet metal substrate and baked, or a conventional resin molded product is pasted on a sheet with a fluororesin on the front and an adhesive tape on the back. It is obtained by attaching.

FIG. 1 (a) shows a cross section of the transport rib perpendicular to the transfer material transport direction. Toyo Dry Lube is placed on a fixing inlet guide 107 which has been previously bent to have a rib having a height of 2 mm. Fluorine resin coat 102 is formed by spraying a PTFE powder paint manufactured by Co., Ltd., dried, and then melted and solidified in an electric furnace. The surface of the transport rib thus obtained is a smooth surface with Rz = 5 μm or less, and has excellent rubbing properties against the paper edge.

FIG. 1B shows a conventional conveyance guide having a resin conveyance guide 103 made of ABS resin and having a height of 2 mm, and a sheet 104 made of a fluororesin having a PTFE adhesive surface as shown in FIG. With an adhesive 105, for example, an industrial Teflon tape # 549 manufactured by Sumitomo 3M.
(Thickness 0.09mm) is bent around the rib top,
It is bonded to the side of the rib. The adhesive used for the sheet bonding surface must be selected so as to withstand a high-temperature and high-humidity environment or long-term use, but a boss may be provided on the side surface of the rib so as to mechanically hold the sheet.

In any case, if a thin fluororesin layer having a thickness of about 20 to 200 μm can be formed on the surface of the rib, a transfer rib having low friction with respect to the transfer material can be obtained.

By using the conveying rib described above, the occurrence of "image scattering" with the conventionally used resin molded product,
The amount of wear (change in height) on the rib surface was compared. As the transport ribs of the examples, those obtained by baking the PTFE resin shown in FIG. 1A were used. For comparison, a transport rib made of POM (polyacetal) was used as Comparative Example 1, and PC-ABS (ABS resin containing polycarbonate) was used. ) Was used as Comparative Example 2.

The phenomenon of "image scattering" is based on a basis weight of 64 g / m ^2.
After passing 30 sheets of neutral paper continuously using an automatic duplexer, evaluation was made on a horizontal halftone image. On the other hand, for the amount of wear of the ribs, a change in the height of the ribs after 300,000 sheets of the same paper were continuously passed was examined. The results are shown in Table 1.

[0039]

[Table 1] As shown in Table 1, in Comparative Example 1, although the amount of abrasion caused by the transfer material was small, "image scattering" occurred, indicating that the chargeability was poor. In Comparative Example 2, the level of “image scattering” was not bad, but the amount of wear of the ribs was large.
A jam occurred around 100,000 sheets. on the other hand,
The conveyance guide of Example 1 had no occurrence of “image scattering” and a small amount of wear. The cause is as described above due to low friction with the transfer material.

It should be noted that only the transport guide or the rib portion
It may be made of fluororesin such as PFA, PTFE, etc.
Since the material cost increases, it is better to form only the surface with a fluororesin layer as in this embodiment.

Embodiment 2 Next, an example in which the present invention is applied to a transport roller disposed between transfer and fixing will be described.

For example, as shown in FIG.
A transfer path 112 that separates the transfer material from the photosensitive drum 1 by a bias applied to the transfer roller 112 includes a transfer roller 111 disposed after a charge elimination needle 110. The transfer material after separation is held by the transport rollers 111 and sent to the fixing device 13.
The transport roller 111 is rotatably attached to the transport path 112, and rotates following the transport of the transfer material.

The reason why such a transport roller 111 is arranged is that, as described in the conventional example, the separation angle from the photosensitive drum 1 is kept as constant as possible for various types of transfer materials, This is for minimizing the peeling discharge of. Since the transport roller 111 is rotatably installed, sliding and charging with the transfer material is unlikely to occur, but when the number of sheets passed increases, the sliding portions such as the shaft and the bearing portion of the transport roller 111 may cause paper dust, toner, etc. Foreign matter is mixed, and rotation resistance is generated.

For this reason, the transport roller 111 is also a factor of causing "image scattering", and has a frictional property with the transfer material.
Improvement of the chargeability is desired.

In the present embodiment, the transport roller is attached to the terminal group.
Using PFA resin having a CF _3.

This PFA resin is excellent in thermal stability and has a lower mold release property even after long-term use, compared to conventional fluororesins, for example, PFA350-J (trade name) manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd. With less static electricity. For example, PFA450HP-J (high viscosity type) and PFA440HP- manufactured by Mitsui DuPont Fluorochemicals Co., Ltd.
J (low viscosity type) is available.

In this embodiment, PFA440HP-J was poured into a mold to obtain a transport roller 106 as shown in FIG.

When the transport roller 106 of this embodiment is mounted in the main body of the image forming apparatus, the life of the main body (750,000 sheets) is reduced.
"Image splatter" was not seen.

In the present embodiment, the transport roller 106 is used behind the static elimination needle after the transfer, but it may be used as a transport path between transfer and fixing in combination with the transport rib as in the first embodiment. Example 3 and Comparative Example 3 Next, an example in which the transferred transfer material is conveyed to the vicinity of a fixing device by an endless belt, and the transfer material is guided to a fixing nip by a fixing entrance guide will be described.

In FIG. 7, reference numeral 113 denotes an endless belt having a dielectric layer made of PVdF (polyvinylidene fluoride) resin, which conveys a transfer material to a fixing side at a constant speed by a driving roller 114. The surface of the endless belt 113 is charged by a charger (not shown), and the transfer material separated from the photosensitive drum 1 is suction-conveyed. 115 is a fixing roller 1
16 is a fixing device that forms a nip with the pressure roller 117 and heats and transports unfixed toner on the transfer material.
A fixing entrance guide 18 guides the transfer material to the fixing nip.

The transfer material conveyed by the endless belt 113 is charged by the charger 119 to the endless belt 11.
After the charge is removed on the roller 3, the tip of the drive roller 114 can be completely separated by the fixing entrance guide 118 by using the curvature of the drive roller 114.

As the fixing entrance guide 118, one having excellent heat resistance such as PBT (polybutylene terephthalate) resin and having a small water absorption is suitable. The reason is that the transfer material does not deform even if it is constantly exposed to the heat released from the fixing device or the heat carried by the transfer material. This leads to image failure. Furthermore, the surface of the fixing entrance guide 118 must be excellent in releasability so that a small amount of fog toner and paper dust carried by the transfer material does not accumulate.

FIG. 4 is a perspective view of the fixing entrance guide 107 of the present embodiment, in which PTFE manufactured by Toyo Dry-Lube Co., Ltd.
Carbon dispersed in powder paint (Model # 815-4)
The conductive paint 109 is baked, the surface resistance is set to 10 ¹⁰ Ω, the fixing entrance guide 107 is attached to the main body of the image forming apparatus, the paper is passed until the life of the main body (750,000 sheets), and “image scattering” and accumulation of toner and the like are performed. I checked the situation.

As Comparative Example 3, a fixing inlet guide having the same shape as before applying the PTFE conductive paint 109 was made of a PBT resin (trade name, Novador, manufactured by Mitsubishi Kasei Kogyo Co., Ltd .;
¹⁰ to 10 ¹² Ω).

[0055] As shown in the above table, the one using the PTFE conductive paint did not show accumulation of toner and the like and no image defect.

PTFE conductive paint 10 on the surface of the fixing entrance guide
9 is preferably adjusted so that its surface resistance value is 10 ⁸ to 10 ¹² Ω. The reason is that the surface resistance value is 1
0 below ⁸ Omega has leaked charge transfer material polka phenomenon occur, in 10 ¹² Omega or because the surface is liable to toner easily adheres charged.

Other Embodiments As shown in FIG. 5, a fixing core guide 136 supports a metal core wire 120 such as stainless steel on the fixing nip side of the fixing inlet guide 136, and a plurality of moldings made of PFA resin by the core wire 120. There is one that penetrates the roller 121 and is rotatably disposed.

The rollers 121 stabilize the transfer of the transfer material to the fixing inlet. In the conventional method, when toner or the like enters the gap between the rollers, heat of the fixing device may hinder rotation, or the toner may adhere to the rollers to disturb the image.

However, the PFA 44 shown in Embodiment 2
When the roller 121 was molded at 0 HP-J, it was confirmed that the charged toner did not adhere and that good conveyance could be performed without affecting the image.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.
A system in which a plurality of transport ribs, rollers, and fixing entrance guides are combined as a transport path also works effectively.

[0061]

As described above, in the image forming apparatus provided with the transport path for transporting the transfer material to the fixing device while supporting the non-print side surface, the surface of the transport path is coated with the low friction resin. This reduces the possibility of electrification and reduces the resistance to rubbing with the transfer material.
In addition, it is possible to prevent the transfer material from being jammed.

[Brief description of the drawings]

FIGS. 1A and 1B are cross-sectional views of a conveyance guide according to a first embodiment.

FIG. 2 is a PTFE sheet of Example 1 shown in FIG. 1 (b).

FIG. 3 is a cross-sectional view and a side view of a transfer roller of a second embodiment in a transfer material transfer direction.

FIG. 4 is a perspective view of a fixing entrance guide according to a third embodiment.

FIG. 5 is a perspective view of a conventional fixing entrance guide supporting rollers.

FIG. 6 is a diagram illustrating a conveyance path in which rollers are arranged between transfer and fixing in Example 2.

FIG. 7 is a diagram illustrating a conveyance path in which a conveyance belt and a fixing entrance guide between transfer and fixing according to a third embodiment are arranged.

FIG. 8 is a diagram illustrating an example of a conventional transfer path between transfer and fixing.

FIG. 9 is a diagram illustrating a transport path provided with a conventional transport rib.

FIG. 10 is a diagram illustrating an image forming apparatus including an automatic double-sided device.

FIG. 11 is a view showing an example of a conventional apparatus provided with a resin-made conveying roller.

FIG. 12 is a diagram showing an example of a conventional device provided with an endless belt.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum 4 transfer roller 8, 110 static elimination needle 10 transport guide 11 resin molding member 12 sheet metal member 13 fixing device 14 transfer guide 19 paper 26 paper feed roller 28 exposure device 29 primary charger 30 developing device 31 registration roller 32, 34, 38, 39, 41, 42, 44 Transport guides 33, 40, 43 Transport rollers 36 Paper cassette 37 Flapper 43, 45 Discharge rollers 46 Discharge tray 47 Exterior 48, 106, 111 Transport rollers 49, 113 Endless belt 50, 119 Charger 51 Separation charger 101 Transport guide sheet metal 102 Fluororesin coat 103 Resin transport guide 104 Fluororesin sheet with adhesive surface 105 Adhesive 107, 118, 136 Fixing entrance guide 108 Iron fixing entrance guide substrate 109 Conductive paint 112 transport path 14 drive roller 115 fixing device 116 fixing roller 117 pressure roller 120 metal cores 121 roller

Claims (7)

[Claims] An image forming apparatus for transferring a toner image on an image carrier onto a transfer material by applying a bias from behind the transfer material and conveying the transfer material to a fixing device, wherein the non-printed surface of the transfer material is An image forming apparatus characterized in that a surface of a conveyance path on which one side or one printing surface rubs is coated with a low friction resin. 2. The image forming apparatus according to claim 1, wherein the low friction resin is a fluororesin layer. 3. The image forming apparatus according to claim 2, wherein the fluororesin layer is a polytetrafluoroethylene resin layer. 4. The image forming apparatus according to claim 2, wherein the fluororesin layer is a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer resin layer having —CF ₃ at a terminal group. 5. The fluororesin layer has a surface resistance of 10 ⁸ to 1
The image forming apparatus according to claim 2, wherein the value is in a range of 0 ¹² Ω. 6. A double-sided printing device, comprising: an automatic double-sided device in which one printing surface side and the other printing image side are automatically conveyed to the fixing device through the conveyance path when performing double-sided printing. The image forming apparatus according to claim 1. 7. The image forming apparatus according to claim 1, wherein the transport path is formed by any one or combination of a fixed rib, a rotatable roller, and a fixing entrance guide.