JPH05313531A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of turbulence in an image on a recording material and fixing of toner at a carrying body, etc., by extending a carrying device carrying the recording material to a position after outlet of a fixing part. CONSTITUTION:A fixing roll 7a as the fixing means and a pressure roller 7b on the opposite side to the fixing roll 7a having the carrying belt 8 between them are provided on the left of an image forming part Pa and the pressure roller 7b positioned opposing to the fixing roll 7a having the carrying roll 8 between them is in a pressurized contact with the fixing roll 7a. Then, when the image forming process is completed, a recording material 6 is carried to the fixing part while still being retained by being attracted to the carrying belt 8 due to electrostatic attraction force generated at each transferring process. The toner on the recording material 6 has the color mixed due to the heat of the fixing roll 7a and the pressurizing force generated between the pressure roller 7b at the fixing part and is fixed to the recording material. Furthermore, when the fixing of the toner to the recording material 6 is completed, the recording material 6 is distributed in a curvature on a following roll 11 and ejected outside the machine by the carrying belt 8.

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, and more particularly to an image forming apparatus having a structure suitable for a color electrophotographic apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus, which has a plurality of image forming units, forms toner images of different colors in each image forming unit, and sequentially transfers the toner images onto the same transfer material, so-called, Although various color image forming apparatuses have been proposed, a color copying apparatus using a multicolor electrophotographic system is widely used.

An example of such a color electrophotographic copying apparatus is shown in FIG.
A brief description will be given based on FIG.

In the main body of the color electrophotographic copying machine shown in FIG. 13, first, second, third and fourth image forming sections Pa, Pb, Pc and Pd are arranged in parallel. The image forming sections Pa, Pb, Pc and Pd each have a dedicated image carrier (electrophotographic photosensitive drums 1a, 1b, 1c and 1d in this example).

The photosensitive drums 1a, 1b, 1c and 1d are
Latent image forming portions 2a, 2b, 2c, 2d, developing portions 3a, 3b, 3c, 3d, and cleaning portions 5a,
5b, 5c, 5d are arranged.

Further, the image forming sections Pa, Pb, Pc, Pd
A recording material conveying belt 8 is disposed below the transfer belt 4 and has transfer units 4a, 4b, 4c, 4 equipped with transfer chargers therein.
d is arranged.

With this structure, first, the latent image forming section 2a forms a latent image corresponding to the cyan component color in the original image on the photosensitive drum 1a of the first image forming section Pa. The latent image is made a visible image by the developer having the cyan toner in the developing section 3a, and the cyan toner image is transferred by the recording material cassette 60 via the registration roller 13 and the conveyor belt 8 in the transfer section 4a. Recording material 6 consisting of sheets such as paper
It is electrostatically transferred by the electric field created by the transfer charger.

On the other hand, while the cyan toner image is being transferred to the recording material as described above, a latent image corresponding to the magenta component color is formed in the second image forming portion Pb, and then the developing portion 3b is formed.
The magenta toner image formed in 1. is transferred to a predetermined position of the recording material 6 when the recording material 6 that has been transferred in the first image forming portion Pa is conveyed to the transfer portion 4b by the conveyor belt 8. ..

Thereafter, the third and fourth methods are performed in the same manner as above.
The image forming units Pc and Pd form yellow and black images, and the yellow and black colors are superimposed and transferred to a predetermined position on the same recording material carried on the conveyor belt 8.

When such an image forming process is completed, the recording material 6 is separated from the conveying belt 8 and then the toner images on the recording material are mixed in the fixing section 7 and fixed on the recording material to obtain a full-color image. On the other hand, each of the photosensitive drums 1a, 1b, 1c, and 1d that has completed the transfer is cleaned by the cleaning units 5a and 5a.
Residual toner is removed by b, 5c, and 5d to prepare for the subsequent latent image formation.

Here, the recording material conveying belt 8 includes a polyethylene terephthalate resin film sheet (PET sheet), a polyvinylidene fluoride resin film sheet,
It is a film made of a dielectric resin such as a polyurethane resin film sheet, and both ends thereof are overlapped and bonded to each other to form an endless shape, or a seamless belt (seamless) is used.

When the conveyor belt 8 starts to rotate, the recording material 6 is conveyed from the registration roller 13 onto the belt.

At this time, the image writing signal is turned on and an image is formed on the first color photosensitive drum 1a at a predetermined timing. Then, when the recording material 6 is conveyed to the contact portion (transfer position) between the photosensitive drum and the conveying belt, an image is formed on the recording material 6 by transfer, and recording is performed by the voltage applied to the transfer charger during the transfer. The material 6 is strongly electrostatically adsorbed on the belt 8. In addition to this, there is a system in which an electric charge is applied to the transport belt 8 in advance, or an electric charge is applied at the same time when the recording material 6 is fed onto the belt 8.

[0014]

In the above conventional example, the toner image on the recording material is attracted to the recording material by electrostatic force, and similarly, the recording material is attracted to the conveying belt by electrostatic force. Therefore, when the recording material is separated from the conveyor belt that has been transported to the fixing portion, peeling causes discharge, which disturbs the toner image on the recording material, and significantly deteriorates the image quality. Such a phenomenon remarkably occurs particularly in a low humidity environment (that is, when the water content of the recording material decreases and the resistance increases). Furthermore, when a toner having a smaller particle size (for example, an average particle size of 18 μm or less) is used as a toner for achieving high image quality, the amount of electric charge per unit mass of the toner particle becomes large, and the electrostatic charge required for transfer is increased. The force also becomes large, and the electrostatic force acting between the recording material and the toner image also becomes large, and the above-mentioned problems occur more remarkably.

On the other hand, in order to solve such a problem, a charging device 61 is provided as shown in FIG. 14 to apply an alternating electric field, so that the recording material or the recording material is separated from the conveying belt before the recording material is separated from the conveying belt. A proposal has been made with the aim of weakening the peeling discharge by reducing the amount of electric charge of the recording medium and making the above-mentioned problems less likely to occur, but it is possible to obtain sufficient effects for various recording materials under different environmental conditions. The reality is that it has not been done. That is, even if such an AC static eliminator is provided, the static eliminator is sometimes too strong and the electrostatic adsorption force between the recording material and the toner layer becomes too weak at one time, and as a result, the recording material is conveyed and the fixing unit is transported. The toner image on the recording material is disturbed by a shock when it rushes into the fixing roller, and the image quality is remarkably deteriorated.In some cases, the charge removal is too weak to improve the image quality for the same reason as described above. Had lowered.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an improved image forming apparatus that does not cause image distortion.

[0017]

In order to solve the above-mentioned problem (that is, the problem that an image is disturbed by an electric discharge when separating a recording medium before fixing from a conveying belt), the present invention conveys the recording medium. It is characterized in that the means is penetrated into the fixing device, and the position for separating the recording medium from the conveying means is the outlet of the fixing device or a position after that. In the image forming apparatus according to the present invention, since the position where the recording medium is separated from the conveying means is the position after the exit of the fixing device, there is no risk of image disturbance.

[0018]

【Example】

(First Embodiment) A first embodiment of the image forming apparatus according to the present invention will be described below with reference to FIG.

FIG. 1 is a sectional view of a color electrophotographic printer showing a first embodiment of the image forming apparatus of the present invention, and FIG.
The same parts as those in FIG.

In the image forming apparatus shown in this embodiment, the image forming sections Pa, Pb, Pc and Pd are arranged in the apparatus main body 10, and the drive roller 12, the driven support roller 11 and the lower side of the image forming section are provided. A recording material carrying means, which is an endless conveyor belt 8 wound around these rollers and having a joint, is provided, and the conveyor belt 8 is rotated in the direction of the arrow. The conveyor belt 8 is made of a dielectric resin sheet such as a polyethylene terephthalate resin sheet or a polyvinylidene fluoride resin sheet.

In the figure, on the right side (feeding side) of the conveyor belt 8, there is arranged a registration roller 13 which is a conveying means for conveying the recording material to the recording material carrying means.

First, second, third and fourth image forming portions Pa, Pb, Pc and Pd arranged in parallel above the conveyor belt 8.
Has photosensitive drums 1a, 1b, 1c and 1d, and chargers 15a, 15b, 15c and 15d are provided on the upper left side of each of the photosensitive drums 1a, 1b, 1c and 1d as shown in FIG.

Further, the photosensitive drums 1a, 1b, 1c, 1d have laser beam scanners 16a, 16b, 1 on their upper portions.
6c and 16d are provided, respectively. These laser beam scanners 16a, 16b, 16c, 16d are composed of a semiconductor laser, a polygon mirror, an fθ lens, etc., receive an electric digital image signal, and charge the laser beam modulated corresponding to the signal with the chargers 15a, 15b. , 1
5c and 15d and the developing devices 3a, 3b, 3c and 3d are formed so as to scan in the generatrix direction of the photosensitive drums 1a, 1b, 1c and 1d to expose them.

Further, each image forming section Pa, Pb, Pc, Pd
A recording material conveying belt 8 is arranged below the recording medium, and transfer chargers 4a, 4b, 4c and 4d are arranged inside the recording material conveying belt 8 as a transfer means for transferring the toner image on the photosensitive drum to the recording material.

Further, on the left side of the image forming section Pa, there are provided a fixing roller 7a as a fixing means and a pressure roller 7b on the opposite side of the conveyance belt. The fixing roller 7a has a structure in which a surface of a metal cored bar is covered with silicone rubber and fluororubber to a predetermined thickness, and includes a heater 10 such as a halogen lamp as a heating means and is rotatable in an arrow direction. Is supported by. On the other hand, the pressure roller 7b, which is opposed to the fixing roller 7a with the conveying belt 8 interposed therebetween, is arranged so as to be in pressure contact with the fixing roller 7a. The pressure roller 7b is a metal cored bar provided with a silicone rubber on the surface thereof and a fluororesin coating on the surface thereof. A heater such as a halogen lamp as a heating means is provided inside the pressure roller 7b as in the fixing roller 7a. It may be provided. Also, this pressure roller
The fixing roller 7b is rotatably supported in the direction of the arrow and has a fixing roller 7b.
It is configured to be driven to rotate. The thermistor 14 is disposed so as to abut on the fixing roller 7a, and the surface temperature of the fixing roller 7a is always 150 to 180 by controlling the voltage to the heater 10 via a temperature adjusting circuit.
It is adjusted so that it can be kept between ℃.

Next, the operation of the image forming apparatus will be described.

First, the photosensitive drum 1 of the first image forming portion Pa
a is charged by the charger 15a, and the laser scanner 16
By irradiating light with a, a latent image corresponding to the cyan component color in the original image is formed. The latent image is made into a visible image by the developer having the cyan toner of the developing unit 3a, and the cyan toner image is transferred to the transfer unit 4a having the transfer charger.
The recording material cassette 60 transfers the recording material 6 to a recording material 6 made of a sheet such as a paper sent by the conveyor belt 8 via the registration rollers 13.

On the other hand, while the cyan toner image is being transferred onto the recording material as described above, the photosensitive drum 1b in the second image forming portion Pb is charged by the charger 15b and is irradiated with light by the laser scanner 6b. The latent image corresponding to the magenta component color is formed on the recording medium 6 after the transfer on the first image forming unit Pa is completed by the transfer belt 8 and the magenta toner image formed on the developing unit 3b is transferred and charged. When it is conveyed to the transfer unit 4b having a container, it is transferred to a predetermined position on the recording material 6.

Thereafter, the third and fourth steps are performed in the same manner as described above.
The image forming units Pc and Pd form yellow and black images, and the yellow and black colors are superimposed and transferred to a predetermined position on the same recording material carried on the conveyor belt 8.

When such an image forming process is completed, the recording material 6 is conveyed to the fixing unit while being attracted and held by the conveyor belt 8 by the electrostatic attraction force generated at each of the transfer steps so far. .. In the fixing unit, the toner on the recording material 6 is mixed by the heat of the fixing roller 7a and the pressure generated between the pressure roller 7b and is fixed on the recording material. When the fixing of the toner to the recording material is completed, the recording material 6 is transferred to the conveyor belt 8
Then, the curvature is separated on the driven roller 11 and the particles are discharged to the outside of the machine. On the other hand, the photosensitive drums 1a, 1b, 1 for which the transfer has been completed
The cleaning units 5a, 5b, 5c, and 5d remove residual toners c and 1d to prepare for the subsequent latent image formation.

Due to such a constitution, the recording material 6
After the upper toner is heated and fixed, the recording material is conveyed to the conveyor belt 8.
As a result, it becomes possible to separate the toner more effectively, and it has become possible to prevent the toner disorder during separation, which has been a problem in the past.

In this embodiment, the curvature separation is applied to separate the recording material from the conveyor belt, but if the separation claw 17 is used as shown in FIG. It is stable and preferable.

Further, as shown in FIG. 3, if a cooling unit 18 including a fan for cooling the conveyor belt 8 after fixing is provided, heat accumulation on the conveyor belt 8 can be prevented. In particular, when the image forming interval is short and the conveying belt is moved at a high speed, the effect is great because the time from when the conveying belt passes through the fixing unit to when it returns to the fixing unit is short. As a cooling method, it goes without saying that a heat pipe or the like may be used in combination with the above fan.

In the present embodiment, in addition to the above-mentioned effects, the toner is fixed on the recording material 6 and then separated from the conveyor belt 8. Therefore, the recording material can be removed without worrying about image distortion at the time of separation. It is possible to separate mechanically and forcibly from the conveyor belt 8 and it is not necessary to use a separation charge-eliminating device or the like, so that the device configuration can be simplified.

(Embodiment 2) In this embodiment, as will be better understood by referring to FIG. 4, in the image forming apparatus shown in the above-mentioned Embodiment 1, the sheet is conveyed as a pressure roller which comes into pressure contact with the fixing roller 7a. The driven roller 11 of the apparatus is also used. At this time, it is possible to use a driving roller as a roller facing the fixing roller 7a,
If the drive roller faces the fixing roller, the diameter of the drive roller is changed by the heat generated by the fixing roller and the moving speed of the conveyor belt is modulated, which is not preferable. Therefore, it is preferable to use the driven roller as the facing roller of the fixing roller. By doing so, not only the effect shown in the above-described embodiment can be obtained, but also the device size can be reduced. Further, in the present embodiment, the diameter of the driven roller changes due to the heat of the fixing roller and the length over which the entire conveyor belt is stretched changes. Therefore, a tension roller 17 is also added to absorb such a length change. The tension roller 17 enables the conveyor belt 8 to be always stably moved without slackening or overtensioning.

(Embodiment 3) In this embodiment, the fixing roller 7a can be brought into contact with and separated from the conveyor belt 8 in the image forming apparatus shown in the above-mentioned Embodiment 1 as shown in FIGS. The pressurizing mechanisms 19a and 19b are provided. Pressure mechanism 1
Each of 9a and 19b has a pressure spring, a solenoid, and a pressure rod inside, and controls the voltage applied to the solenoid based on a signal from an arithmetic processing unit (not shown) provided in the image forming apparatus. As a result, the pressure applied by the pressure spring can be applied to the fixing roller 7a. With such a configuration, the recording material 6 becomes the recording material cassette 6
0, the toner image is transferred on each of the image forming portions Pa, Pb, Pc, and Pd, and the leading end of the toner image is transferred to the fixing portion. And 19b are operated to bring the fixing roller 7a into pressure contact with the pressure roller 7b. Then, after that, when the recording material has finished passing through the fixing portion, the pressing force is promptly released. With such a configuration, unnecessary heat is prevented from being accumulated in the conveyor belt, and the accident that the toner directly attached to the conveyor belt 8 due to an accident or the like is fixed to the conveyor belt is prevented. It has become possible.

(Embodiment 4) In this embodiment shown in FIG. 7, a fixing device 30 having an endless belt-shaped fixing film is used instead of the heating roller type fixing device.

Next, the fixing device 30 will be described with reference to FIGS.
Will be described.

In FIG. 8, reference numeral 24 denotes an endless belt-shaped fixing film, which has a left driving roller 25, a right driven roller 26, a driving roller 25 and a driven roller 26.
The low-heat-capacity linear heating element 20 as a heating element arranged below the space is suspended and stretched between the four members 25, 26, 27, 20 parallel to each other.

The driven roller 26 also serves as a tension roller for the endless belt-shaped fixing film 24, and the fixing film 24 is rotated at a predetermined peripheral speed in the clockwise direction with the clockwise rotation of the driving roller 25, that is, the image forming portion. The unfixed toner image conveyed from the side is rotationally driven at the same peripheral speed as the conveying speed of the recording material 6 carrying the upper surface without wrinkles, meandering, or speed delay.

Reference numeral 28 is a pressure roller as a pressure member having a rubber elastic layer with good releasability such as silicon rubber,
The lower film portion of the endless belt-shaped fixing film 24 is sandwiched and is pressed against the lower surface of the heating body 20 by an urging means (not shown) at a total pressure of 4 to 7 kg. 6 rotates in the forward counterclockwise direction in the transport direction.

The linear heating element 20 having a low heat capacity as a heating element in this example is the same as that in the transverse direction of the fixing film (fixing film 2).
Rigidity of the lateral hand with the longitudinal direction of 4)
A heater substrate 21 having a heater support 27 having high heat resistance and heat insulation, and a heating element 22 and a temperature measuring element 23 integrally attached and held on the lower surface side of the heater support 27 along the lower surface length. To have.

The heater support 27 heat-insulates and supports the heating body 20 with respect to the fixing device 11 and the entire copying machine. For example, PPS (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether ether). It can be made of high heat resistant resin such as ketone) or liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like.

The heater substrate 21 has a thickness of 1.0 m as an example.
It is an alumina substrate having m, a width of 10 mm, and a length of mm.
For example, the heating element 22 is formed by coating an electric resistance material such as Ag / Pd (silver-palladium) to a thickness of about 10 μm and a width of 1 to 3 mm by screen printing or the like along the longitudinal direction at a substantially central portion of the lower surface of the heater substrate 21. Then, a heat-resistant glass 21a as a surface protective layer is coated thereon by about 10 μm.

The temperature detecting element 23 is, for example, the heater substrate 21.
Is a resistance temperature detector having a low heat capacity, such as a Pt film, which is provided by coating the upper surface (the surface opposite to the surface on which the heating element is provided) of substantially the center thereof with screen printing or the like. As the temperature detecting element, a thermistor having a low heat capacity may be arranged in contact with the substrate.

In the case of the heating element 20 of this example, electricity is applied to the linear or strip heating element 22 from both ends in the longitudinal direction, and the heating element 22 is caused to generate heat over substantially the entire length. The energization is AC 100V, and the energization power is controlled by controlling the phase angle of energization by an energization control circuit (not shown) including a triac according to the temperature detected by the temperature detecting element 23.

The fixing film 24 has heat resistance, releasability and durability, and is generally 100 μm or less, preferably 40 μm.
Single-layer or composite-layer films of m or less can be used.

The figure is a schematic cross-sectional view of the layer structure of an example of a composite layer film, wherein 24a is a heat-resistant layer as a base layer (base film) of the fixing film, and 24b is an outer surface of the heat-resistant layer 24a (on the side facing the toner image). It is a release layer laminated on the surface).

The heat-resistant layer 24a is a high heat-resistant resin film such as polyimide, polyetheretherketone (PEEK), polyethersulfone (PES), polyetherimide (PEI), polyparabanic acid (PPA), or the like.
Metals such as Ni, SUS, and Al that have excellent strength and heat resistance can be used.

The release layer 24b is made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene) / PFA / FEP. Release layer 24b for heat-resistant layer 24a
Is formed by adhesive lamination of release layer film, lamination by film forming technology such as electrostatic coating (coating), vapor deposition, CVD of release layer material, two-layer film by coextrusion of heat resistant layer material and release layer material. It can be carried out by activating.

Next, the operation of the apparatus of this embodiment will be described.
The operation in the image forming process before the fixing process has been described in each of the above-described embodiments, and thus the description thereof is omitted.

When the image forming process is completed, the recording material 6 is conveyed to the fixing portion while being adsorbed and held on the conveying belt 8 by the static electricity generated by each of the transfer steps so far. In the fixing unit, the recording material 6 is fixed to the fixing film 24 at the pressure contact portion N between the heating body 20 and the pressure roller 28 and the pressure roller 2.
8 and the unfixed toner image surface comes into close contact with the lower surface of the fixing film 24 which is rotated in the same direction at the same speed as the conveying speed of the recording material 6 without causing surface deviation or wrinkling. In the overlapping state with the fixing film 24, the heating body 20 and the pressure roller 28 pass while being pressed between the mutual pressure contact portions N. The heating body 20 is electrically heated immediately before the recording material 6 rushes into the pressure contact portion N by the image formation start signal.

The heat generated by the heating element 20 is applied to the fixing film 2
Since the heat capacity of No. 4 is very small, it is quickly transferred to the surface of the fixing film 24, and the surface of the fixing film 24 reaches the fixing possible temperature immediately. When the recording material 6 has finished passing through the pressure contact portion N, the energization is stopped and the surface of the fixing film 24 is immediately cooled.

When the fixing of the toner on the recording material 6 is completed as described above, the recording material 6 is curvature-separated from the conveying belt 8 on the driven roller 11 and is discharged to the outside of the machine. On the other hand, the residual toner is removed from the photosensitive drums 1a, 1b, 1c, 1d after the transfer is completed by the cleaning units 5a, 5b, 5c, 5d, and they are prepared for the subsequent latent image formation.

With such a configuration, the recording material can be separated from the conveyor belt 8 after the toner on the recording material 6 is heated and fixed, and the toner disturbance at the time of separation, which has been a problem in the related art. Can be prevented.

Further, according to this structure, unnecessary heat is prevented from being accumulated in the conveyor belt 8, and the fog toner and scattered toner attached to the conveyor belt portion on which the recording material 6 is not placed are conveyed. It can also be prevented from directly fixing on the.

In this embodiment, the curvature separation is applied to separate the recording material from the conveyor belt, but if the separation claw 17 is used as shown in FIG. Is stable and preferable.

In the present embodiment, in addition to the above-described effects, the toner is fixed on the recording material 6 and then the recording material 6 is separated from the conveying belt 8. Therefore, the recording material is conveyed without worrying about image disturbance at the time of separation. It is possible to separate the belt 8 mechanically and forcibly, and it is not necessary to use a separation charge-eliminating device or the like, so that the device configuration can be simplified.

(Fifth Embodiment) FIG. 11 is a schematic view showing the arrangement of an image forming apparatus according to the fifth embodiment of the present invention. This embodiment is a modification of the embodiment shown in FIG. 4, and the above-mentioned fixing film type fixing device 30 is installed in place of the heating roller type fixing device in the configuration of FIG. Therefore, the driven roller 11 of the recording material conveying device also serves as the pressure roller 28 of the fixing device 30, and according to this embodiment, the same effect as the embodiment of FIG. 4 can be obtained.

The description of the operation of each part in this embodiment will be omitted.

FIG. 12 shows an embodiment relating to the heating body 20 in the fixing device 30 using the endless belt-shaped fixing film shown in FIGS.

As shown in FIG. 12, the heating element 20 of this embodiment has heating elements 22 and 22 in the heating element 20.
It is characterized in that it is divided into three parts 2, 2 and 223, and switches 29a and 29b for switching the heating element to be energized are provided together with the power supply 31. Heating elements 221, 222, 223
Has a length of 260 mm, 20 mm, and 20 mm in the direction perpendicular to the moving direction of the conveyor belt 8. Further, the center of the heating element 221 is arranged so as to coincide with the center when the recording material 6 moves on the conveyor belt 8.

When an image is formed by A4 size horizontal feed or A3 size vertical feed, a heating element 221 is used.
Switch 29a so that all 222, 223 can be energized
And 29b are controlled by a control means (not shown) so that only the heating element 221 can be energized when an image is formed by B5 size horizontal feed or B4 size vertical feed.
It was configured to control a and 29b.

When an image is formed by an image forming apparatus having such a fixing device, in addition to the effect obtained in the above embodiment, the length in the direction perpendicular to the conveying direction is shorter than that of the A4 or A3 size. Even when the B5 or B4 size paper is passed, the heat generating portion always corresponds to the place where the recording material exists, so that the recording material 6 is not placed even when the B printing material is passed. It is possible to prevent the fogging toner and the scattered toner attached to the belt portion from directly fixing on the conveyor belt 8.

In this embodiment, since the size of the recording material to be passed is A4, A3, B5, B4, the heating elements are divided as shown in FIG. It goes without saying that the same preferable result can be obtained by changing the number of divisions or the lengths of individual heating elements according to the type.

[0066]

As described above, in the image forming apparatus of the present invention, since the conveying device for conveying the recording material is extended to the position after the exit of the fixing section, when the recording material enters the fixing section. Need not be separated from the carrier, and
According to the image forming apparatus of the present invention, occurrence of phenomena such as occurrence of image disturbance on a recording material and fixing of toner dropped on a carrier on the carrier is prevented. Can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a first embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram showing a part of a modified embodiment of the apparatus of FIG.

FIG. 3 is a diagram showing a modified embodiment of the apparatus of FIG.

FIG. 4 is a schematic diagram showing a configuration of an image forming apparatus according to a second embodiment of the present invention.

5 is a diagram showing a modified example of a part of the apparatus shown in FIG.

6 is a diagram showing a modified example of a part of the device shown in FIG.

FIG. 7 is a diagram showing a modified example of the device shown in FIG.

8 is a schematic side view of a fixing film type fixing device provided in the image forming apparatus shown in FIG.

9 is a diagram showing a structure of a fixing film of the fixing device shown in FIG.

10 is a diagram showing a modified example of a part of the device shown in FIG.

11 is a diagram showing a modified example of the device shown in FIG.

12 is a diagram showing a modified example of a heating element in the fixing film type fixing device shown in FIG.

FIG. 13 is a diagram showing a configuration of a conventional image forming apparatus.

FIG. 14 is a diagram showing a part of a conventional image forming apparatus proposed to eliminate the drawbacks of the apparatus shown in FIG.

[Explanation of symbols]

6 ... Recording material 8 ... Conveying belt 17 ... Separation claw 20 ... Heating element 21 ... Heater substrate 21a ... Heat-resistant glass 22 ... Heating element 23 ... Temperature measuring element 24 ... Fixing film 25 ... Driving roller 26 ... Driven roller 27 ... Heater support 28 ... Pressure roller 29a, 29b ... Switch 31 ... Power supply 221, 222, 2
23 ... Heating element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/20 108

Claims (5)

[Claims] 1. An image forming apparatus having an image forming section and a fixing section, wherein a recording medium having an image transferred by the image forming section is fed to the fixing section. From the fixing unit to the recording unit after the image is fixed, the recording unit after the image is fixed is provided at the exit of the fixing unit. An image forming apparatus characterized in that it is released from the conveying means at a subsequent position. 2. The transport means is configured as a transport device having an endless belt-shaped transport body, and the winding roller of the transport body also functions as a pressure roller of the fixing section. The image forming apparatus according to item 1. 3. The transport means is configured as a transport device having an endless belt-shaped transport body, and the winding roller of the transport body is provided at a position after the exit of the fixing unit. The image forming apparatus according to claim 1. 4. The fixing unit is configured as a fixing device of a type that uses an endless belt-shaped fixing film, and the conveying unit is configured as a conveying device of a type that moves an endless belt-shaped carrier. 2. The winding roller of the carrier also serves as a pressure roller of the fixing device.
Image forming device. 5. The fixing unit is configured as a fixing device of a type that uses an endless belt-shaped fixing film, and the conveying unit is configured as a conveying device that uses an endless belt-shaped conveying body. The body feeding roller is provided at a position after the exit of the fixing device.
Image forming device.