JP2002031964A - Image forming method and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image of high image quality where no wrinkles are formed on paper after heating and pressing in regard to an image forming device adapting an simultaneous transfer and fixing method where a toner image is transferred and fixed to the paper simultaneously by being heated and pressed. SOLUTION: In the image forming method, the toner image is carried on a sheet-like toner carrier, a recording medium is superimposed on the toner image, the toner image having the recording medium superimposed is heated and pressed, and sandwiched toner is cooled while the toner image carrier and the recording medium are still superimposed after the heating and the pressing is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention employs a simultaneous transfer and fixing system for transferring a toner image on a toner image carrier onto a recording medium and fixing the toner image on the recording medium during the transfer. The present invention relates to an image forming apparatus such as a printer and a copying machine.

[0002]

2. Description of the Related Art Conventionally, an image forming method of forming an electrostatic latent image on a photoreceptor, developing the electrostatic latent image with a dry toner, electrostatically transferring the toner image to a recording medium, and fixing the image is widely used. Have been. In such an image forming method, due to unevenness of the surface of paper as a recording medium, the paper and the photoreceptor do not completely adhere to each other, an uneven gap is generated, a transfer electric field is disturbed, and a coulomb between toners is generated. There is a problem that the image is disturbed due to repulsion or the like.

To solve this problem, toner images of different colors are electrostatically superimposedly transferred onto an intermediate transfer member, and a multicolor multi-toner image is fused on the intermediate transfer member. An image forming method for transferring and fixing a multi-layered toner image at the same time as a transfer to obtain a color copy, or melting an toner image on a photoconductor formed in an endless belt shape and transferring and fixing the image on a recording medium to obtain an image Such an image forming method has been devised. In this method, since the transfer of the toner image to the recording medium is performed in a non-electrostatic manner, the image quality is hardly deteriorated as described above.

On the other hand, such an image forming method is disclosed in US Pat. No. 2,990,278 and Japanese Patent Laid-Open No. 5-19.
As disclosed in JP-A-642, JP-A-5-107950 and JP-A-5-249798, transfer of a toner image from a toner image carrier such as an intermediate transfer member or a photoreceptor to a recording medium is prevented. In order to improve the quality, the toner is cooled and solidified while the toner image carrier and the toner and the recording medium are superposed after the contact heating and pressurization, and then the toner image carrier and the toner and the recording medium are separated. It has been proposed. In this method, the toner and the toner image carrier are separated after the cohesive force between the toners becomes larger than the adhesive force between the toner and the toner image carrier, so that a part of the toner remains on the toner image carrier. So-called offset can be prevented, so that oil-less operation is possible, and color transfer is improved due to high toner transfer efficiency. Furthermore, since the toner solidifies along the surface of the toner image carrier, the use of a toner image carrier having a smooth surface enables high-quality, high-quality images with high gloss and excellent toner transparency. Can be obtained.

FIG. 12 is a schematic configuration diagram of an image forming apparatus employing a simultaneous transfer and fixing system.

In this image forming apparatus, four roll-shaped photoconductors 1_1, 1_2, 1_3, and 1_4 are arranged, and these photoconductors rotate in the directions of the arrows while rotating the chargers 10_1, 10_2, and 10_2. 10 _ 3, 10 _ 4, are uniformly charged, and are scanned by a light beam modulated according to a density signal from the light beam scanning device 20 to form electrostatic latent images on the respective photoconductors. Each developing unit 11_1, containing magenta and cyan toners,
By 11_2, 11_4, and 11_4, the electrostatic latent image is developed with toner of each color, and a toner image of each color is formed on each photoconductor.

The image forming apparatus includes a roller 5_
1, 5_2, 5_3, 5_4 and the heating roller 2, and four photoconductors 1_1, 1_2, 1_3, 1_
Endless belt-shaped intermediate transfer body 50 circulating along
Is provided. The intermediate transfer member 50 moves along each of the photoconductors 1_1, 1_2, 1_3, and 1_4 in a state where a predetermined tension is applied by the tension roll 5_3, and is operated by the transfer devices 50_1, 50_2, 50_3, and 50_4. The toner images of each color formed on each photoconductor are transferred onto the intermediate transfer body so as to be sequentially superimposed.

When the intermediate transfer member 50 reaches the heating section A wound around the heating roll 2, the color toner image on which the toner images of the respective colors are superimposed is melted by the heat source 20 disposed inside the heating roll 2. Then, the image reaches the transfer fixing section B. In the transfer and fixing section B, the sheet 60 stored in the sheet tray 6 passes through the sheet feed roll 6_1, the guide roll 6_2, and the registration roll 6_3 so that the toner image is sandwiched between the sheet 60 and the intermediate transfer body 50. Supplied with timing.

In the transfer and fixing section B, a pressure roll 3 is disposed so as to face the heating roll 2.
Is pressed against the heating roll 2 at the same time as the feeding of the paper 60 from the tray 6, and in the transfer and fixing section B, the intermediate transfer body 50, the toner image, and the paper 60 are integrally added to the heating roll 2. It is sandwiched between the pressure rolls 3 and is heated and pressurized. The toner image that has passed through the holding portion sandwiched between the heating roll 2 and the pressure roll 3 is continuously cooled by the cooling device 4 while being sandwiched between the intermediate transfer body 50 and the paper 60.
The paper 60 is separated from the intermediate transfer body 50 together with the toner by the rigidity of the paper 60 itself on the peeling roll 5_4 having a small radius of curvature after being cooled and solidified, and the separated paper 60 is further transported by the paper transport device 7. And
The image is output to the outside of the image forming apparatus, and an image including the fixed toner image is formed on the sheet 60.

[0010]

However, when an image is formed by such an image forming apparatus, as shown in FIG. 13, on the heated and pressurized paper 60, a direction perpendicular to the paper advancing direction is applied. A large number of wrinkles 61 may occur, causing a phenomenon in which the toner is separated from the intermediate transfer member before the toner is cooled and solidified. When such a phenomenon occurs, paper 6
Not only do wrinkles occur at 0, but the image quality deteriorates significantly. That is, FIG. 14 shows a cross-sectional state of the intermediate transfer body, the toner, and the paper along the paper advancing direction. In a wrinkled portion of the paper 60, the intermediate transfer is performed before the toner 100 is cooled and solidified. The body 50 and the toner 100 are separated. Therefore, the toner 100 does not solidify along the surface of the intermediate transfer body 50, and the toner surface at that portion becomes uneven, the gloss is reduced, and the image quality is significantly deteriorated. Here, the case where the toner on the paper is transferred and fixed via the intermediate transfer member has been described. However, the same applies to the case where the toner image is directly transferred and fixed from the belt-shaped photosensitive member onto the paper.

In view of the above problems, the present invention transfers a toner image on a toner image carrier onto a recording medium,
An image forming apparatus employing a simultaneous transfer and fixing method of fixing a toner image on a recording medium during the transfer, wherein an image forming method capable of obtaining a high-quality image without uneven gloss is provided.
And an image forming apparatus employing the image forming method.

[0012]

According to a first aspect of the present invention, there is provided an image forming method comprising the steps of: carrying a toner image on a sheet-like toner carrier; and carrying the toner image. A sheet-shaped recording medium is superimposed on the toner image carrier so as to sandwich the toner image carried on the toner image carrier, and is sandwiched between the toner image carrier and the recording medium in the superimposed state. Heating and pressurizing the toner image
After the heating and pressurization are released, the toner image held between the toner image carrier and the recording medium is cooled while the toner image carrier and the recording medium are superimposed, so that the toner image fixed on the recording medium is removed from the toner image. In an image forming method for forming an image, a toner image carrier and a toner image sandwiched between the recording media are heated and pressed while the superimposed toner image carrier and the recording medium are curved, and the heating and heating are performed. Even after the pressure is released, the toner image carrier and the recording medium maintain their curvature during heating and pressing until the toner image melted by the heating and pressing is cooled to a temperature equal to or lower than the melting temperature. It is characterized by being placed in a state.

According to a second image forming method of the image forming method of the present invention for achieving the above object, a toner image carrier having a toner image carried on a sheet-like toner carrier is provided. A sheet-shaped recording medium is superimposed on the toner image carrier, sandwiching the toner image carried on the toner image carrier, and the toner image carrier and the toner image sandwiched by the recording medium in the superimposed state are superposed. After heating and pressurizing and releasing the heating and pressurizing, the toner image carrier and the recording medium are superimposed, and the toner image sandwiched between the toner image carrier and the recording medium is cooled to fix the toner image on the recording medium. In the image forming method for forming an image formed of a toner image formed by applying heat, the superimposed toner image carrier and the recording medium are released from the heating and pressurization simultaneously with the curved state of the toner image carrier and the recording medium. Characterized in that placed in a state of being released from the restriction to an external force.

According to a first aspect of the present invention, there is provided an image forming apparatus for forming an image comprising a fixed toner image on a predetermined recording medium. A sheet-shaped toner image carrier that carries the toner image and conveys it to a predetermined transfer position; a toner image forming unit that forms a toner image on the toner image carrier; and a sheet-shaped recording medium at the transfer position. A recording medium transporting unit that adjusts the timing so that the toner image carried on the toner image carrier is superimposed on the toner image carrier with a gap therebetween, and supplies the toner image. While regulating the movement paths of the toner image carrier and the recording medium so that the toner image carrier and the recording medium are kept flat, the toner image carrier and the toner image sandwiched between the recording media are heated and heated. Heating and pressurizing means for applying pressure, wherein the heat and pressurizing means includes two rolls of the same diameter and the same material, which press against each other with the toner image carrier and the recording medium interposed therebetween. Or two members for holding the toner image carrier and the recording medium between two planes and pressing each other.

Further, a second one of the image forming apparatuses of the present invention.
Is an image forming apparatus that forms an image composed of a fixed toner image on a predetermined recording medium,
A sheet-shaped toner image carrier that carries the toner image and conveys it to a predetermined transfer position; a toner image forming unit that forms a toner image on the toner image carrier; and a sheet-shaped recording medium at the transfer position. A recording medium conveying means for supplying a toner image carried on the toner image carrier at an adjusted timing so as to be superimposed on the toner image carrier with a gap therebetween; Heating and pressurizing means for heating and pressurizing the toner image held between the moving toner image carrier and the recording medium in a state where the toner image carrier and the recording medium are curved; After the pressure is released, until the toner image melted by the heating and pressurization is cooled to a melting temperature or lower, the toner image carrier and the recording medium superimposed on each other are curved when heated and pressurized. Characterized in that a movement path restricting means for restricting the movement path of the toner image bearing member to move while Tsu.

Further, a third image forming apparatus among the image forming apparatuses of the present invention for achieving the above object is an image forming apparatus for forming an image comprising a fixed toner image on a predetermined recording medium. A sheet-shaped toner image carrier that carries the toner image and conveys it to a predetermined transfer position; a toner image forming unit that forms a toner image on the toner image carrier; and a sheet-shaped recording medium at the transfer position. A recording medium transporting means for supplying a toner image carried on the toner image carrier at an adjusted timing so as to be superimposed on the toner image carrier with a gap therebetween; In a state where the toner image carrier and the recording medium are curved, while heating and pressing the toner image sandwiched between the moving toner image carrier and the recording medium, and simultaneously releasing the heating and pressurizing, The toner image bearing member and the recording medium, characterized by comprising a heating and pressing means for placing the state of being released the bent state from an external force for regulating the toner image bearing member and the recording medium.

In the first to third image forming apparatuses of the present invention, the toner image forming means may directly form a toner image on a toner image carrier, but is not limited thereto. A toner image is formed on a member other than the toner image carrier according to the present invention, and the toner image is transferred onto the toner image carrier to form a toner image on the toner image carrier. You may.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the cause of the occurrence of wrinkles in paper or the like due to transfer and fixing will be considered, and then the embodiments of the present invention will be described.

In the image forming apparatus shown in FIG. 12, as described above, the transfer / fixing section B includes the heating roll 2 and the pressure roll 3, and these two rolls are brought into contact with each other, and an intermediate transfer member is placed therebetween. By sandwiching the sheet 50 and the sheet 60, the toner image sandwiched between the intermediate transfer body 50 and the sheet 60 is heated and pressed.

In the transfer fixing section B, the intermediate transfer member 50
The toner image and the paper 60 are integrally brought into close contact with each other and heated, and the powder toner is brought into a molten state, and the individual toners are fused to form one film. At this time, the intermediate transfer body 50 and the paper 60 need to be in close contact with each other in order to efficiently transfer heat to the toner image. If this cannot be achieved and air enters somewhere, the heat capacity is reduced in places where air exists and where there is no air. Alternately, the toner image is not uniformly melted, causing transfer / fixing unevenness or a so-called offset phenomenon, resulting in deterioration of image quality. An elastic layer is provided on the surface of the intermediate transfer member 50 in order to improve the adhesion between the intermediate transfer member 50 and the sheet 60 with the toner image interposed therebetween. Further, the heating roll 2 and the pressure roll 3 are also provided with an elastic layer on the surface layer in order to apply a uniform pressure. However, the heating roll 2 includes the intermediate transfer member 5
In order to efficiently heat the toner on the upper side, the elastic layer is made thinner, and the elastic layer of the pressure roll 3 is made thicker to have elasticity, thereby forming a holding portion. The holding portion thus formed has a shape in which the heating roll 2 with a thin elastic layer bites into the pressure roll with a thick elastic layer, and the radius of the roll on the biting side is r, and the curvature is 1 / r ≧ C. It becomes a state curved at C. Usually, since both rolls are provided with an elastic layer, 1 / r = C does not hold and 1 / r> C holds.

As a result of various experiments, the present inventors have found that the above-described paper wrinkles are caused by this curvature at the holding portion.

First, the inventors change the curvature C of the sandwiching portion of the transfer fixing portion B by changing the thickness of the elastic layer of the heating roll 2 and the pressing roll 3 to obtain a short sheet-like intermediate transfer member. The sheet 50 and the sheet 60 were overlapped and passed through the holding section of the transfer fixing section. FIGS. 1 and 2 show the shapes of the intermediate transfer body 50 and the sheet in a state of being in close contact after passing through the holding portion at that time. FIG. 1 is a diagram when the thickness t of the elastic layer of the heating roll 2 is 0.5 mm and the thickness t of the elastic layer of the pressing roll 3 is 3 mm, and FIG. Thickness t = 3mm,
It is a figure at the time of thickness t = 0.5 mm of the elastic layer of a pressure roll. As shown in these figures, it was found that the intermediate transfer body 50 and the paper 60 that were pressed and adhered to each other at the sandwiching portion passed through the sandwiching portion while curling according to the curvature of the sandwiching portion. In other words, when heated and pressurized in a state of curvature, the outer periphery becomes longer and the inner periphery becomes shorter, so that they are in close contact with each other, and there is a difference between the outer peripheral length and the inner peripheral length. As a result, the adhered object retains the curvature and curls.

Next, the present inventors applied tension to the intermediate transfer body 50 and the paper 60 which were obtained in the first experiment and were in close contact with the curl, and tried to straighten them. 3 and 4 show the state of the intermediate transfer body 50 and the sheet 60 at that time. FIG. 3 is a diagram corresponding to FIG. 1 and illustrates a state in which tension is applied in a state where the intermediate transfer body 50 is curled so as to form the inner periphery and the sheet 60 forms the outer periphery, and FIG. FIG. 3 corresponds to FIG. 2 and illustrates a state where tension is applied in a state in which the intermediate transfer body 50 is curled so as to form an outer periphery and a sheet 60 forms an inner periphery. As shown in these figures, by applying tension, the intermediate transfer body 50 and the paper 60 are separated from each other in a direction perpendicular to the direction in which the tension is applied and parallel to each other, so that the outer periphery is formed on the wrinkles. It turned out to be.

From these experiments, the present inventors guessed the cause of the aforementioned paper wrinkles as follows. In the clamping section,
The heating roll 2, the intermediate transfer body 50, the paper 60, and the pressure roll 3 overlap in this order, and at the holding portion, as described above, the heating roll 2 having a thin elastic layer bites into the pressure roll 3 having a large elastic layer. I have. Therefore, as shown in the above-described first experiment, the intermediate transfer body 50 has an inner periphery, and the paper 60 has an outer periphery. When the intermediate transfer member 50 passes through the holding portion, the intermediate transfer member 50 receives tension and is stretched straight. Therefore, as shown in the above-described second experiment in which the tension is applied in a curled state, the direction in which the tension is applied is perpendicular to the direction in which the tension is applied. In some directions, the sheets 60 are separated from each other in a certain direction, and the paper 60 on the outer periphery becomes wrinkled. As described above, the wrinkles cause uneven gloss.

Therefore, as one method of suppressing the occurrence of wrinkles, the intermediate transfer body 50 and the paper 60
To eliminate the difference between the outer peripheral length and the inner peripheral length.

FIG. 5 is a schematic diagram showing a state in which the curvatures of the intermediate transfer body 50 and the paper 60 in close contact with each other are reversed halfway.

As shown in FIG. 5, when the curvature is reversed,
Solving the simple geometry yields the difference L between the outer and inner circumferences.
Indicates that the thickness of the sheet 60 is tp (mm), the thickness of the intermediate transfer body 50 is tb (mm), and the wrapping angle of the holding portion is θ1.
(Rad), the winding angle of the inverted portion is θ2 (ra
Assuming d), L = (tb + tp) · (θ1−θ2).

That is, the winding angle θ1 (ra
By making the winding angle θ2 (rad) the same as that of d) and the inverted part, the difference between the outer peripheral length and the inner peripheral length can be eliminated. However, actually, due to the thermal contraction and thermal expansion of the sheet 60 and the intermediate transfer body 50, the wrapping angle θ1
The difference between the outer peripheral length and the inner peripheral length is eliminated in a state where there is a difference in the winding angle θ2 of the inverted portion.

Instead of inverting the curvature in the middle as shown in FIG. 5, the curvature at the holding portion may be eliminated so that the difference between the outer peripheral length and the inner peripheral length does not occur. Alternatively, the existence of the difference between the outer peripheral length and the inner peripheral length is allowed, and the curved state of the closely adhered intermediate transfer body 50 and the sheet 60 due to the difference between the outer peripheral length and the inner peripheral length after passing through the holding portion is maintained. By keeping the state, the intermediate transfer body 50 and the sheet 60 may not be peeled off. As a method of maintaining the curved state after passing through the sandwiching section, the intermediate transfer body or the sheet is maintained by applying an external force so that the curved state of the same curvature as that of the sandwiching section is maintained. Alternatively, the curved state may be maintained by leaving the intermediate transfer body and the sheet in a state where they are released from an external force that regulates the curved state.

FIG. 6 is a diagram showing a first configuration example of the image forming apparatus.

In the configuration example shown in FIG. 6, the heating and pressing means presses each other with the toner image carrier (in the present embodiment, an endless belt-shaped intermediate transfer body) interposed therebetween, and presses the portions pressed by each other. And two rolls forming a holding portion curved so as to bite into a predetermined first roll side, and a toner image carrier is conveyed along the first roll before reaching the holding portion. A toner image carrier movement path regulating member that regulates the movement path of the toner image carrier, wherein the recording medium supply means moves the sheet-like recording medium through a first roll and a toner that moves along the first roll. A configuration is provided in which the toner is supplied so as to be sandwiched between the image bearing members.

In FIG. 6, the intermediate transfer body 50 in the form of an endless belt is supported by rolls 5_1, 5_2, 5_3, 5_4, a heating plate 9, and a curvature reversing roll 8, and circulates in the direction of the arrow shown in the figure. A pressure roll 3 is arranged to face the heating roll 2. The heating roll 2 and the pressure roll 3 can be arranged in reverse, and the pressure roll 3 may be a heating roll having a heat source inside. The heating plate 9 is constituted by a plate having a heat source. Four photoconductors 1_1, 1_2, 1_3, and 1_4 are arranged around the intermediate transfer body 50, and the chargers 10_1, 10_2, and 10_, respectively.
After being uniformly charged by 3 and 10_4, it is exposed by a scanning device 20 that scans a light beam that is turned on and off by a light beam pulse width modulator (not shown) according to the density signal, and an electrostatic latent image is formed. You. The electrostatic latent images on the respective photoconductors are respectively developed by developing units 11_1, 11_2, 11_3 containing black, yellow, magenta, and cyan toners.
A toner image of each color of a so-called digital image, which is developed by 11_4 and whose density is represented by area modulation, is formed on each photoconductor. Each color toner image is transferred to each transfer device 50.
_1, 50_2, 50_3, and 50_4 are sequentially transferred to the intermediate transfer body 50, and a toner image of a plurality of colors is formed on the intermediate transfer body 50.

The toner image formed on the intermediate transfer member 50 contacts the heating plate 9 and is heated and melted.

The pressure roll 3 comes into pressure contact with the heating roll 2 as the paper 60 is fed from the tray 6 via the paper transport rolls 6_1, 6_2, and 6_3. First, the toner image of a plurality of colors held by the intermediate transfer body 50 is sandwiched between the intermediate transfer body 50 and the sheet 60, and the intermediate transfer body 6
In addition, the intermediate transfer body 50 and the paper 60 are moved between the heating roll 2 and the pressure roll 3 to be further pressurized by being pressed against the pressure roll 3 by 0. Is done. The toner heated to the melting temperature or higher is softened and melted, penetrates into the paper 60, and is then solidified, thereby performing transfer and fixing. The cooling device 4 cools the intermediate transfer body 50 and the sheet 60 that are conveyed integrally from the heating area. The cooling by the cooling device 4 causes the toner to coagulate and solidify, and a strong adhesive force with the sheet 60 is generated. . The intermediate transfer body 50 and the sheet 60 cooled by the cooling device 4 are further conveyed, and the sheet 60 is transferred to the sheet 6 on the peeling roll 5_4 having a small radius of curvature.
The toner image is separated from the intermediate transfer member 50 together with the toner by the stiffness of the toner image itself, and a color image including the toner image fixed on the sheet 60 is formed. The paper 60 on which the color image has been formed is discharged to the outside by the paper discharge belt 7. The surface of the toner image transferred and fixed on the paper 60 is smoothed to have a high gloss following the surface of the intermediate transfer body 50.

As the photoconductors 1_1, 1_2, 1_3, and 1_4, various inorganic photoconductors (Se, a-Si, a-Si
C, CdS, etc.) and various organic photoreceptors can be used.

The toner is composed of a thermoplastic binder containing dyes such as yellow, magenta, and cyan, and can be made of a known material. In this configuration example, the weight average molecular weight (Mw) is 54000, and the melting temperature (Tm) is 120 °.
C. A toner having a viscosity (η) of 4000 Pas at a melting temperature was used. The average particle diameter of the toner was 7 μm. The toner amount of each color toner on the paper 60 is about 0.4 mg / cm ² to about 0.4 mg / cm ² depending on the content of the pigment.
Exposure conditions or development conditions are set so as to be 7 mg / cm ² . Here, for each color, 0.65 mg / cm
Set to ² .

The intermediate transfer member 50 is composed of a base layer and a surface layer.
A layered structure was used.

For the base layer of the intermediate transfer member 50, a 70 μm thick polyimide film to which carbon black was added was used. In this embodiment, the volume resistivity of the base layer is adjusted to 10 ¹⁰ Ωcm by changing the amount of added carbon black in order to electrostatically transfer the toner image from the photoreceptor to the intermediate transfer member without image disturbance. did. As the base layer, for example, a highly heat-resistant sheet having a thickness of 10 to 300 μm can be used, and polyester, polyethylene terephthalate, polyether sulfone,
A polymer sheet such as polyetherketone, polysulfone, polyimide, polyimideamide, or polyamide can be used.

The volume resistivity of the surface layer of the intermediate transfer member 50 is adjusted to 10 ¹⁴ Ωcm in order to electrostatically transfer the toner image from the photoreceptor to the intermediate transfer member without image disturbance.
In addition, a silicone copolymer having a rubber hardness of 30 degrees and a thickness of 50 μm was used in order to sandwich the toner image and improve the adhesion between the intermediate transfer body and the paper when performing simultaneous transfer and fixing from the intermediate transfer body to the paper. . The silicone copolymer has elasticity, and its surface shows adhesiveness to the toner at room temperature.
Since the toner has the property of easily releasing the toner that has been melted and fluidized, the toner can be efficiently transferred to paper, and is optimal for the surface layer.

As the heating plate 9, an aluminum plate having a thickness of 2 mm and a length of 220 mm in the direction of circulation of the intermediate transfer member and having a silicon rubber heater attached to the back thereof was used. The heating temperature is set and controlled so that the toner temperature in a region where the intermediate transfer body contacts the sheet is equal to or higher than the toner melting temperature (Tm). In addition, a ceramic heater or the like can be used as the heating plate 9.

As the heating roll 2 and the pressure roll 3, a metal roll or a roll having a heat-resistant elastic layer such as silicone rubber on a metal roll can be used.
A heat source 20 is disposed inside the heating roll 2, and its heating temperature is determined by the toner temperature in the heating area and the toner melting temperature (T
m) or more. In this embodiment, an outer diameter of 50 mm is formed by laminating a silicone rubber having a hardness of 30 degrees and a thickness of 0.5 mm on a hollow aluminum roll.
mm heating roller 2 and a pressure roller 3 having an outer diameter of 50 mm and having a thickness of 3 mm laminated with silicone rubber having a hardness of 30 degrees on a hollow aluminum roll. As a heat source 20 inside the heating roll, a halogen lamp is used. I'm using The pressing force of both the heating and pressurizing rolls is adjusted so that the width of the holding portion in the intermediate transfer body conveyance direction (referred to as holding width) is 7.5 mm. The holding part is
The heating roll 2 is formed so as to bite into the pressure roll 3.

The curvature reversing roll 8 has a surface covered with silicon rubber with a thickness of 1 mm as a heat insulating layer so that the heat of the intermediate transfer body 50 is not released to the curvature reversing roll 8, and has a diameter of 2 mm.
A 5 mm stainless steel hollow roll is used.
FIG. 7 shows an enlarged view of this part. The intermediate transfer body 50 is once pressed by the curvature reversing roll 8 against the pressure roll 3 before entering the holding portion sandwiched between the heating roll 2 and the pressure roll 3. As a result, the toner image on the intermediate transfer body 50 is pressed against the pressure roll 3 via the paper and is pressed. As a result, as shown in FIG. 7, a curvature reversal portion C having a curvature opposite to that of the holding portion N is formed. Curvature reversal part C
Is adjusted by adjusting the height of the curvature reversing roll 8. Here, the width of the curvature reversal portion C is 6.5 mm.
Set to. In forming the curvature reversing portion C, in addition to the configuration using the curvature reversing roll 8 shown here, a wedge-shaped metal piece 81 having a heat source 80 therein, as shown in FIGS.
There is also a configuration example in which a rod-shaped pad 82 having a heat insulating layer on the surface is employed.

The paper 60 is J paper manufactured by Fuji Xerox Co., Ltd. as plain paper, and S paper manufactured by Fuji Xerox Co., Ltd. as thin paper.
Paper was used, and Shiraoi Paper made by Daishowa Paper was used as cardboard. The measured value of the ten-point average thickness of J paper is approximately 96μ.
m, and the measured value of the ten-point average thickness of the S paper is approximately 7
6 μm, the measured value of the ten-point average thickness of Shiraishi paper is approximately 2
10 μm.

The screen uses vertical lines, and has 20 lines.
Line 0.

With the above configuration, an image is output on plain paper (J paper), thin paper (S paper), and thick paper (Shiraoi) at a conveying speed (transfer fixing speed) of the intermediate transfer body and the toner image of 240 mm / s. , Paper wrinkles and uneven gloss were evaluated. as a result,
In each case, a good image without wrinkles and uneven gloss was obtained.

FIG. 10 is a diagram showing a second configuration example of the image forming apparatus.

In the configuration example shown in FIG. 10, a belt-shaped photoconductor 1 is provided.
1, 5_2, 5_3, and 5_4, supported by the heating plate 9 and the curvature reversing roll 8, are circulated in the arrow direction shown in the figure. The heating roll 2 is provided with a pressure roll 3 facing away from the heating roll 2. The heating roll 2 and the pressure roll 3 can be arranged in reverse, and the pressure roll 3 may be a heating roll having a heat source inside. Photoconductor 1 is a charger 1
After being uniformly charged by 0, it is exposed by a light beam scanning device 20 that scans a light beam that is turned on and off by a light beam pulse width modulation device (not shown) according to the density signal, and an electrostatic latent image is formed. You. The electrostatic latent image is stored in the developing device 11_1.
, And a toner image of a so-called digital image whose density is represented by area modulation is formed on the photoconductor 1. Each developing unit 11_1, 11_2, 11_3, 11_
4 includes black, yellow, magenta, and cyan toners. By repeating the above-described charging, exposure, and development, a toner image of a plurality of colors is formed on the photoconductor 1.

The toner image formed on the photosensitive member 1 contacts the heating plate 9 and is heated and melted.

The pressure roll 3 is used to move the paper 60 from the tray 6
To the heating roll 2 at the same time as the sheet feeding. The toner image of a plurality of colors held on the photoconductor 1 is first pressed by the photoconductor 1 against the pressure roll 3 while being sandwiched between the photoconductor 1 and the paper 60, and then is pressed. By moving between the heating roll 2 and the pressure roll 3, the pressure is further increased and the heating is performed. The toner heated to the melting temperature or higher is softened and melted, penetrates into the paper 60, and is then solidified, thereby performing transfer and fixing. The photoreceptor 1 and the sheet 60 cooled by the cooling device 4 are conveyed, and the sheet 60 is separated from the photoreceptor 1 together with the toner by the strength of the sheet 60 itself and the toner on the separation roll 5 </ b> _ 4 having a small radius of curvature. Thus, a color image composed of the fixed-color toner images is formed. Paper 60 on which a color image is formed
Is discharged from the paper discharge belt 7 to the outside. Paper 60
The surface of the toner image transferred and fixed onto the surface of the photoconductor 1 is smoothed to have a high glossiness.

As the photosensitive member 1, various photosensitive members having heat resistance (Se, a-Si, a-SiC, CdS, etc.) can be used.

The same toner as in the first embodiment is used, and the amount of each color toner on the recording paper is set to 0.65 mg / cm ² , the same as in the first embodiment.

The same heating plate 9 as in the first embodiment is used.

The heating roll 2 and the pressure roll 3 are the same as those in the first embodiment.

As the curvature reversing roll 8, the same one as in the first embodiment is used.

As the paper 60, J paper and S paper manufactured by Fuji Xerox Co., Ltd., and Shiroi Paper manufactured by Daishowa Paper Co., Ltd. are used as in the first embodiment.

The screen uses vertical lines as in the first configuration example, and has 200 lines.

With the above configuration, an image is output on plain paper (J paper), thin paper (S paper), and thick paper (Shiraoi) at a conveying speed (transfer fixing speed) of the photosensitive member and the toner image of 240 mm / s. , Paper wrinkles and uneven gloss were evaluated. as a result,
In each case, a good image without paper wrinkles and without uneven gloss was obtained.

Hereinafter, embodiments of the present invention will be described.

FIG. 11 is a diagram showing the configuration of the first embodiment of the image forming apparatus of the present invention. The embodiment shown in FIG. 11 is an embodiment of the first image forming apparatus of the present invention, and presses each other with a toner image carrier and a recording medium interposed therebetween as heating and pressing means, This is an embodiment including two rolls of the same material.

In the first embodiment of the image forming apparatus of the present invention shown in FIG. 11, an intermediate transfer member 50, a photosensitive member for forming an image on the intermediate transfer member 50, a charger, a light beam scanning device, and a developing device Device and transfer device are the first configuration example (see FIG. 6)
The description is omitted.

The heating plate 9 is the same as that in the first configuration example (see FIG. 6), but by adjusting the height of the end in the downstream example in the intermediate transfer body circulation direction, the intermediate transfer body 50 The heating roll 2 and the pressure roll 3 are not in contact with the pressure roll 3.
Is adjusted so as to be guided to the holding portion.

As the heating roll 2, a silicone rubber having a hardness of 30 degrees was formed on a hollow aluminum roll to a thickness of 3 mm.
And a heating roll having an outer diameter of 50 mm. The same roll as the heating roll is used for the pressure roll 3. That is, the pressure roll 3 is also a roll having an outer diameter of 50 mm, in which a silicone rubber having a hardness of 30 degrees is laminated with a thickness of 3 mm on a hollow roll of aluminum. As a heat source 20 inside the heating roll, a halogen lamp was used. The pressing force of both the heating and pressing rolls is changed and adjusted so that the holding width is 7.5 mm.
When the shape of the holding portion at this time was visually observed from the side, it was almost straight.

In the above arrangement, the conveying speed (transfer fixing speed) of the photosensitive member and the toner image is 240 mm / s, and the plain paper (J
(Paper), thin paper (S paper), and thick paper (Shiraoi), and images were evaluated for paper wrinkles and gloss unevenness. As a result, in each case, a good image was obtained without paper wrinkles and without uneven gloss.

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

FIG. 12 is a diagram showing the configuration of a second embodiment of the image forming apparatus of the present invention.

The embodiment shown in FIG. 12 is also an embodiment of the first image forming apparatus of the present invention like the embodiment of FIG. 11, but is different from the embodiment of FIG. This is an embodiment provided with two members that press the toner image carrier and the recording medium against each other while sandwiching them between planes.

The second embodiment of the image forming apparatus of the present invention shown in FIG.
In the embodiment, the intermediate transfer body 50, and a photoconductor, a charger, a light beam scanning device, a developing unit, and a transfer unit for forming an image on the intermediate transfer body 50 are the same as those in the first configuration example (see FIG. 6). And the description is omitted.

The intermediate transfer member 50 has rolls 5_1 and 5_
It is supported by 2, 5_3, 5_4, and 5_5, and circulates in the illustrated arrow direction.

The heating and pressurizing plate 21 is a pair of aluminum plates having a thickness of 2 mm and a length of 130 mm in the direction of circulation of the intermediate transfer member with a silicone rubber heater attached to the back surface. The contacting portion is provided with a Teflon (registered trademark) resin layer having a thickness of 10 μm in order to reduce friction. The heating temperature is set and controlled so that the toner temperature in the heating area is equal to or higher than the toner melting temperature (Tm). These two pairs of heating and pressing plates 21 are pressed against each other by a pressing device (not shown), and by changing the pressing force, the surface pressure is 3 kg / c.
It is adjusted to m ^2. The shape of the heating / pressing portion at this time was visually observed and found to be substantially straight.

In the above configuration, the conveying speed (transfer fixing speed) of the photosensitive member and the toner image is 160 mm / s, and the plain paper (J
(Paper), thin paper (S paper), and thick paper (Shiraoi), and images were evaluated for paper wrinkles and gloss unevenness. As a result, in each case, a good image was obtained without paper wrinkles and without uneven gloss.

Next, a description will be given of a third embodiment of the image forming apparatus according to the present invention.

FIG. 13 is a diagram showing the configuration of the third embodiment of the image forming apparatus of the present invention. The embodiment shown in FIG. 13 is an embodiment of the second image forming apparatus of the present invention employing the embodiment of the first image forming method of the present invention.

The third embodiment of the image forming apparatus of the present invention shown in FIG.
In the embodiment, the intermediate transfer body 50, and a photoconductor, a charger, a light beam scanning device, a developing unit, and a transfer unit for forming an image on the intermediate transfer body 50 are the same as those in the first configuration example (see FIG. 6). And the description is omitted.

The intermediate transfer member 50 includes rolls 5_1 and 5_
2, 5_3, 5_4 and the heating roll 2, and circulates in the direction of the arrow shown in the figure.

The multicolor toner image formed on the intermediate transfer member 50 is heated and melted while being wrapped around the heating roll 2 and circulating.

The heating roll 2 and the pressure roll 3 are formed by laminating a silicone rubber having a hardness of 30 degrees with a thickness of 1 mm on a hollow aluminum roll, and having a diameter of 80 mm.
And a pressure roll having an outer diameter of 80 mm in which a silicone rubber having a hardness of 30 degrees was laminated with a thickness of 3 mm on a hollow roll of aluminum, and as a heat source 20 inside the heating roll,
Uses a halogen lamp. The holding width is 6.
The pressing force of both the heating and pressing rolls 2 and 3 is changed and adjusted so as to be 5 mm. The holding portion is a heating roll 2
Are formed so as to bite into the pressure roll 3.

The pressure roll 3 is used to move the paper 60 from the tray 6
To the heating roll 2 at the same time as the sheet feeding. Thereafter, the sheet is moved between the heating roll 2 and the pressure roll 3 in a state where the intermediate transfer body 50 holding the fused toner images of a plurality of colors and the sheet 60 are superimposed, and is heated under pressure. The toner heated above the melting temperature will soften,
The toner is melted, penetrates into the paper 60, and then solidifies, whereby transfer and fixing is performed.

The cooling device 41 with a curvature guide is configured such that the surface in contact with the intermediate transfer member 50 passes through the holding portion between the heating roll 2 and the pressure roll 3 and the intermediate transfer member 50 and the paper 6
It is machined to have almost the same curvature as the curvature occurring at zero. Thereby, the intermediate transfer body 50 and the sheet 60 can be circulated to the sheet peeling roll 5_4 in a state of being kept in close contact.
The cooling device 41 with a curvature guide includes an intermediate transfer body 50 and a sheet 60 that are integrally transported from the heating area.
Is cooled, whereby the toner is coagulated and solidified, and a strong adhesive force with the paper 60 is generated.

The intermediate transfer member 50 and the sheet 60 cooled by the cooling device 41 with a curvature guide are further conveyed, and the sheet 60 is separated from the intermediate transfer member 50 by the stiffness of the sheet 60 itself on the peeling roll 5_4 having a small radius of curvature. Separated with the toner, a color image is formed on the paper 60. The surface of the toner image transferred and fixed on the paper 60 is smoothed to have a high gloss following the surface of the intermediate transfer body 50.

In the above configuration, the conveying speed (transfer fixing speed) of the photosensitive member and the toner image is 120 mm / s, and the plain paper (J
(Paper), thin paper (S paper), and thick paper (Shiraoi), and images were evaluated for paper wrinkles and gloss unevenness. As a result, in each case, a good image was obtained without paper wrinkles and without uneven gloss.

Next, a fourth embodiment of the image forming apparatus of the present invention will be described.

FIG. 14 is a diagram showing the configuration of the fourth embodiment of the image forming apparatus of the present invention. The embodiment shown in FIG. 14 is an embodiment of the third image forming apparatus of the present invention employing the embodiment of the second image forming method of the present invention.

The fourth embodiment of the image forming apparatus of the present invention shown in FIG.
In the embodiment, the photoconductor, the charger, the light beam scanning device, and the developing device for forming an image on the intermediate transfer body 50 are the same as those in the first configuration example (see FIG. 6), and the description thereof is omitted. .

The intermediate transfer member 50 is the same as that of the first configuration example, but is not an endless belt but a short sheet-like member.
Will be sent. Each photoconductor 1_1, 1_2, 1_3, 1_4
The toner images of the respective colors formed thereon are sequentially transferred onto the sheet-shaped intermediate transfer body 50 sent on the guide 80 by the roll-shaped transfer units 51_1, 51_2, 51_3, and 51_4. A toner image of a plurality of colors is formed.

The intermediate transfer body 50 holding the toner images of a plurality of colors overlaps with the sheet 60 sent from the tray 6 at the same timing as the intermediate transfer body 50, and the heating roll and the sheet 60 Are sent to a holding section formed by the pressure roll 3 pressed against the roll 2 and heated under pressure.

The toner heated above the melting temperature is softened,
The toner is melted, penetrates into the paper 60, and then solidifies, whereby transfer and fixing is performed.

The intermediate transfer member 50 and the sheet 60 that have passed through the holding portion formed by the heating roll 2 and the pressure roll 3
It is released from the external force for maintaining the curvature, and moves along the discharge section guide 81.

The discharge section guide 81 is bent so as to maintain the curvature generated in the intermediate transfer body 50 and the sheet 60 in accordance with the curvature of the holding section, and the ejection section guide 81 is pushed out of the holding section and climbs over the bending section 81a. The intermediate transfer body 50 includes an inclined portion 81b that is moved and cooled. The cooling device 42 is configured to push the intermediate transfer member 5 pushed out of the holding portion and over the bent portion 81a.
0 and the sheet 60 are cooled, whereby the toner is coagulated and solidified, and a strong adhesive force is generated between the toner and the sheet 60. The cooling device 42 is a blowing type cooling device, and the wind force causes the intermediate transfer body 50 and the paper 60
Also has the function of sending to the discharge unit.

The intermediate transfer body 50 and the paper 60 sent to the discharge section are separated into the intermediate transfer body 50 and the paper 60 by a peeling device (not shown) or manually, and a color image is formed on the paper 60. The surface of the toner image transferred and fixed on the paper 60 is smoothed to have a high gloss following the surface of the intermediate transfer body 50.

The heating roll 2 and the pressure roll 3 were formed by laminating a silicone rubber having a hardness of 30 degrees with a thickness of 0.5 mm on an aluminum hollow roll. 30 mm silicone rubber laminated at a thickness of 3 mm, outer diameter 80 mm
And a halogen lamp is used as the heat source 20 inside the heating roll. The pressure roll 3 also has a heat source 20 inside, and similarly to the heating roll 2, a halogen lamp is used as the internal heat source. The pressing force of both the heating and pressing rolls is changed and adjusted so that the holding width is 7.5 mm. The holding portion is formed in such a manner that the heating roll 2 bites into the pressure roll 3.

In the above-described configuration, the conveying speed (transfer fixing speed) of the photosensitive member and the toner image is 160 mm / s, and the plain paper (J
(Paper), thin paper (S paper), and thick paper (Shiraoi), and images were evaluated for paper wrinkles and gloss unevenness. As a result, in each case, a good image was obtained without paper wrinkles and without uneven gloss.

[0092]

According to the present invention, an image forming method having the above-described structure and operation, which can obtain a high-quality image without gloss unevenness, and a high-quality image obtained by employing this image forming method. And an image forming apparatus capable of providing the same.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a state in which an intermediate transfer body and a sheet that are in close contact with each other are curled.

FIG. 2 is a schematic diagram illustrating a state in which a sheet and an intermediate transfer member that are in close contact are curled.

FIG. 3 is a schematic diagram illustrating a state in which tension is applied to an intermediate transfer body and a sheet that are closely attached and curled.

FIG. 4 is a schematic diagram showing a state in which tension is applied to an intermediate transfer body and a sheet that are closely attached and curled.

FIG. 5 is a schematic diagram illustrating a state in which the curvatures of the intermediate transfer body and the sheet in close contact with each other are reversed halfway;

FIG. 6 is a diagram illustrating a first configuration example of an image forming apparatus.

FIG. 7 is an enlarged view illustrating a part of a first configuration example of the image forming apparatus.

FIG. 8 is a diagram illustrating another example of a part of the first configuration example of the image forming apparatus.

FIG. 9 is a diagram illustrating another example of a part of the first configuration example of the image forming apparatus.

FIG. 10 is a diagram illustrating a second configuration example of the image forming apparatus.

FIG. 11 is a configuration diagram of an image forming apparatus according to the first embodiment of the present invention.

FIG. 12 is a configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 13 is a configuration diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 14 is a configuration diagram of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 15 is a configuration diagram of a conventional image forming apparatus.

FIG. 16 is an explanatory diagram of a conventional problem.

FIG. 17 is a sectional view for explaining a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1_1, 1_2, 1_3, 1_4 Photoreceptor 2 Heating roll 3 Pressure roll 4 Cooling device 5_1, 5_2, 5_3, 5_4, 5_5, 5_6 Roll 6 Paper tray 6_1, 6_2, 6_3 Paper transport roll 7 Paper discharge belt 8 Curve reversal Roll 9 Heating plate 10, 10_1, 10_2, 10_3, 10_4 Charger 11_1, 11_2, 11_3, 11_4 Developing device 20 Exposure device 21 Heating and pressing plate 41 Cooling device with curvature guide 42 Ventilation cooling device 50 Intermediate transfer body 50_1, 50_2, 50_3 , 50_4 transfer unit 60 recording paper 80 guide 81 discharge unit guide 82 pad 90 intermediate transfer body feeding device 100 toner

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichi Fukuda 430 Nakai-cho, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture Inside Fuji Xerox Fuji Xerox Co., Ltd. (72) Inventor Tetsuo Yamada 430 Sakai, Nakai-cho, Ashigarakami-gun, Kanagawa 430 Green Tech Nakai Fuji Xerox Co., Ltd. (72) Inventor Kaku Kitano 430 Sakai Nakaicho, Ashigarakami-gun, Kanagawa Prefecture Green Tech Nakai Inside Fuji Xerox Co., Ltd. (72) Inventor Kazuhiko Arai 430 Sakai Nakaicho Sakaikami-gun, Kanagawa Prefecture Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 2H033 AA01 AA15 BA10 BA15 BA29 BE09 2H078 AA01 BB01 BB12 CC06 DD42 DD51 DD57 2H200 FA17 GA12 GA23 GA47 GB22 GB40 JA07 JA08 JB06 JB18 JB43 JC03 KA03 KA13 LA31

Claims (5)

[Claims] 1. A sheet-like toner carrier having a toner image carried thereon, and the toner image carried on the toner image carrier being sandwiched between the toner images carried on the toner image carrier. The toner image carrier and the recording medium are heated and pressurized, and the heating and pressurization are released, and the toner image carrier and the recording medium are released. Cooling the toner image sandwiched between the toner image carrier and the recording medium with the toner image superimposed on the recording medium, thereby forming an image including the fixed toner image on the recording medium. In a state where the image carrier and the recording medium are curved, the toner image sandwiched between the toner image carrier and the recording medium is heated and pressurized. Image forming, wherein the toner image carrier and the recording medium are kept in a curved state when heated and pressed until the melted toner image is cooled to a temperature lower than the melting temperature. Method. 2. A sheet-like toner carrier having a toner image carried thereon, and a toner image carrier carrying the toner image sandwiched between the toner images carried on the toner image carrier. The toner image carrier and the recording medium are heated and pressurized, and the heating and pressurization are released, and the toner image carrier and the recording medium are released. Cooling the toner image sandwiched between the toner image carrier and the recording medium with the toner image superimposed on the recording medium, thereby forming an image including the fixed toner image on the recording medium. An image forming apparatus, wherein the image carrier and the recording medium are released from an external force that regulates a curved state of the toner image carrier and the recording medium simultaneously with the release of the heating and the pressurization. Method. 3. An image forming apparatus for forming an image comprising a fixed toner image on a predetermined recording medium, comprising: a sheet-shaped toner image carrier for carrying the toner image and transporting the toner image to a predetermined transfer position; A toner image forming means for forming a toner image on the toner image carrier; and a toner image formed on the sheet-shaped recording medium at the transfer position with the toner image carried on the toner image carrier interposed therebetween. A recording medium transporting unit that adjusts and supplies timing so that the toner image carrier and the recording medium are superimposed on the carrier; and a moving path of the superimposed toner image carrier and the recording medium at the transfer position. Heating and pressurizing means for heating and pressurizing the toner image sandwiched between the toner image carrier and the recording medium while regulating the toner image carrier to be kept flat. And two rolls of the same diameter and the same material, which are pressed against each other with the recording medium interposed therebetween, or the toner image carrier and the recording medium are pressed against each other with flat surfaces interposed between them An image forming apparatus comprising two members. 4. An image forming apparatus for forming an image comprising a fixed toner image on a predetermined recording medium, comprising: a sheet-like toner image carrier for carrying the toner image and transporting the toner image to a predetermined transfer position; A toner image forming means for forming a toner image on the toner image carrier; and a toner image formed on the sheet-shaped recording medium at the transfer position with the toner image carried on the toner image carrier interposed therebetween. A recording medium transporting unit that adjusts the timing so as to be superimposed on the carrier, and supplies the toner image while moving the superimposed toner image carrier and the recording medium in the transfer position in a curved state; Heating and pressurizing means for heating and pressurizing the toner image sandwiched between the body and the recording medium; and after the heating and pressurizing by the heating and pressurizing means are released, the toner image melted by the heating and pressurizing is melted. A movement that regulates a movement path of the toner image carrier so that the toner image carrier and the recording medium superimposed on each other move while maintaining the curvature at the time of heating and pressurizing until the toner image carrier is cooled below the temperature. An image forming apparatus comprising: a path regulating unit. 5. An image forming apparatus for forming an image comprising a fixed toner image on a predetermined recording medium, comprising: a sheet-shaped toner image carrier for carrying the toner image and transporting the toner image to a predetermined transfer position; A toner image forming means for forming a toner image on the toner image carrier; and a toner image formed on the sheet-shaped recording medium at the transfer position with the toner image carried on the toner image carrier interposed therebetween. A recording medium transporting unit that adjusts the timing so as to be superimposed on the carrier, and supplies the toner image while moving the superimposed toner image carrier and the recording medium in the transfer position in a curved state; Heating and pressurizing the toner image sandwiched between the body and the recording medium, and simultaneously releasing the heating and pressurizing, the toner image carrier and the recording medium are curved. An image forming apparatus characterized in that a heating and pressing means for placing the state released from an external force to regulate the condition.