JPH0611977A - Image forming device - Google Patents

Abstract

PURPOSE:To enable simultaneous thermal melting transcribe and fixing of a multiplex toner image onto a recording medium with small energy while holding high recording speed by slowing down the speed of an intermediate transcribing rotor below the other process speed during transcribing/fixing processes. CONSTITUTION:Rotation of a rotor 2 is controlled so that the surface speed of the intermediate transcribing rotor 2 at meltingly transcribing a multiplex toner image from the rotor 2 to a transfer paper 26 is slower than the surface speed at transcribing a toner image from a photosensitive body 1 to the rotor 2. Consequently, the passing time of the multiplex toner image through the contact part between the rotor 2 and the transfer paper 26 can be prolonged. Hereby, heat of the toner in melted condition on the rotor 2 is removed by the transfer paper 26 at meltingly transcribing the multiplex toner image onto the transfer paper 26, so as to prevent a trouble of quick solidification of the toner on the transfer paper 26. Namely, it is unnecessary to heat the rotor 2 and a pressing roller 21 up to so high temperature by heaters 19, 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, such as a copying machine or a printer, for recording image information on a recording medium with toner, and more particularly to an apparatus for obtaining a high quality multicolor image.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, offset printing is the best method for improving image quality. Conventionally widely used electrophotographic technology (that is, an electrostatic latent image is formed on a toner image carrier composed of a photoconductor by image exposure, and the electrostatic latent image is developed as a toner image with toner, and then electrostatic discharge is performed by corona discharge. The problem with the technology of transferring that toner image to a recording medium such as paper and fixing it)
That is, density unevenness occurs in the image, or toner scatters at the transfer portion, causing background stain on the image. There is also a problem that the resolution and dot reproducibility are poor.

This is largely due to the transfer process. That is, due to the unevenness of the surface of the paper, the paper and the photoconductor do not completely adhere to each other, a non-uniform gap appears, the transfer electric field is disturbed, and the Coulomb repulsion between the toners is caused, so that the image Quality is deteriorated.

By the way, conventionally, a method is known in which a toner image formed on a photoreceptor is adhesively transferred to an intermediate transfer rotator, and then the toner is thermally melt-transferred from the intermediate transfer rotator to a recording medium (paper) (for example, JP-B-46-41679). In this method, since the toner image is transferred onto the recording medium in a non-electrostatic manner, the above-mentioned deterioration of image quality is less likely to occur.

Further, toner images of different colors are electrostatically superposed and transferred onto the intermediate transfer rotator, and the multi-color multiple toner images are melted on the intermediate transfer rotator and then melted on the recording medium. A technique for transferring a multiple toner image to obtain a color copy is proposed in, for example, Japanese Patent Laid-Open No. 51-94939. Also by this method, the toner image is transferred to the recording medium in a non-electrostatic manner, so that the deterioration of the image quality as described above hardly occurs. In this type of image forming apparatus, a multicolor multi-toner image formed on an intermediate transfer rotator is externally heated by a heater, and the toner is melted and then collectively transferred to a recording medium.

However, as a result of various tests conducted by the present inventor on the image forming apparatus, defective transfer of the multi-toner image from the intermediate transfer rotator to the recording medium and fixing of the toner image transferred onto the recording medium were found. It turns out that a defect occurs.

Upon investigating the cause, the heat of the toner in a molten state on the intermediate transfer rotator is taken to the recording medium during transfer to the recording medium, and the toner is solidified on the recording medium. It has become clear that there is a cause.

In order to eliminate such a defect, it is sufficient to transfer the multiple toner image on the intermediate transfer rotator onto the recording medium while heating the recording medium, thereby improving the transferability and fixing property. You can

However, heating the recording medium as described above requires a large amount of heat energy. Further, the recording medium is usually pressed against the intermediate transfer rotator by a recording medium pressing means such as a pressure roller at the time of transferring the multiple toner image. It is also preferable to heat the intermediate transfer rotator and the recording medium pressing means. However, in this way, the heat energy consumed is increased more and more.

Further, if the intermediate transfer rotator is constructed so as to naturally radiate or forcibly cool the intermediate transfer rotator after transferring the multiple toner images onto the recording medium, the heat energy loss increases.

The above-mentioned problem regarding the consumption of heat energy becomes more important as the recording speed of the image forming apparatus is increased. That is, when the recording speed is increased, it is necessary to increase the rotation speed of the photoconductor or the intermediate transfer rotator and also the conveyance speed of the recording medium. However, when the recording medium is conveyed at such a high speed, heat is applied to the recording medium. Therefore, the amount of heat applied to the recording medium or the like must be further increased.
This increases the heat energy consumed. Conversely, in order to reduce the amount of heat energy consumed, the recording speed must be greatly reduced.

Further, in the image forming apparatus of the above-mentioned type, the recording medium is conveyed to the transfer portion in order to melt transfer the multicolor multiple toner images on the intermediate transfer rotator to the recording medium. When a conveyance trouble occurs on the recording medium, the multiple toner images formed on the intermediate transfer rotator by the processes up to that point are wasted. That is, this toner image must be removed from the intermediate transfer rotator by the cleaning device, and the image forming operation must be redone, resulting in a great loss both economically and in terms of time.

Further, recording medium pressing means for pressing the recording medium on which the multiple toner images are transferred to the intermediate transfer rotator,
Moreover, when the pressing means is also configured to heat,
When the use of the image forming apparatus is started, it is necessary to start the actual image forming operation after heating the recording medium pressing means to a predetermined temperature or higher, which inevitably reduces the work efficiency. A warming-up time is required until the temperature of the recording medium pressing means rises above a predetermined temperature, and the operator must wait during this time.

[0014]

SUMMARY OF THE INVENTION A first object of the present invention is to successively transfer toner images of different colors formed on a toner image carrier to an intermediate transfer rotator, and to form on the intermediate transfer rotator. An image forming apparatus of a type in which multiple toner images are collectively melt-transferred onto a recording medium without toner scattering.
It has good dot and line reproducibility, gradation reproducibility, and resolution, and efficiently fuses multiple toner images to a recording medium with a small amount of heat energy without significantly reducing the recording speed, and fixes this. It is to provide an image forming apparatus capable of performing the above.

A second object of the present invention is to provide an image forming apparatus capable of appropriately performing the subsequent processing while minimizing waste of time and resources even when a recording medium conveyance trouble occurs. It is to be.

A third object of the present invention is to provide an image forming apparatus capable of minimizing the warm-up time even when the recording medium pressing means and the heating means are used.

[0017]

In order to achieve the first object of the present invention, a toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface and a toner image carrier on the outer peripheral surface are provided. While the toner image carrier rotates, the toner images of different colors, which are sequentially formed on the toner image carrier, are superimposed and transferred so as to form a multiple toner image, and The toner heating means for melting the multiple toner images on the intermediate transfer rotator and the surface linear velocity of the intermediate transfer rotator from the toner image carrier to the intermediate transfer rotator so that the toner image can be melt-transferred onto the recording medium. An image forming apparatus provided with drive control means for rotationally driving the intermediate transfer rotator so that the time when the multiple toner images are transferred from the intermediate transfer rotator to the recording medium is slower than when the toner image is transferred. To propose.

At this time, when the toner image on the toner image carrier is transferred onto the intermediate transfer rotator, the toner image carrier and the intermediate transfer rotator are brought into contact with each other to form a multiple toner image on the recording medium. It is advantageous to provide a contacting / separating means for bringing the toner image holding member and the intermediate transfer rotating member into a non-contact state when the transfer is carried out on the recording medium.

In order to achieve the second object of the present invention, the toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface and the outer peripheral surface rotate while being in contact with the toner image carrier. Between the intermediate transfer rotator and toner images of different colors, which are sequentially formed on the toner image carrier, are transferred so as to form a multiple toner image, and the multiple toner images on the intermediate transfer rotator are recorded on the recording medium. A toner heating unit that melts the multiple toner image on the intermediate transfer rotator so that the multiple toner image on the intermediate transfer rotator can be melt-transferred to the recording medium, and a recording medium transport that transports the recording medium to transfer the multiple toner image on the intermediate transfer rotator. Means, a recording medium conveyance detecting means for detecting that the recording medium is conveyed, a warning generating means for issuing a warning when the conveyance of the recording medium is not detected by the recording medium conveyance detecting means, and a multi-toner Recording medium pressing means for pressing the recording medium on which the image is transferred to the intermediate transfer rotator, and when the conveyance of the recording medium is detected by the recording medium conveyance detecting means, the multiple toner image on the intermediate transfer rotator is recorded on the recording medium. The intermediate transfer rotary member continues to rotate so that the recording medium can be transferred onto the intermediate transfer rotary member, and the recording medium pressing unit is operated to press the recording medium against the intermediate transfer rotary member. If not detected, the warning means is actuated so as to give a warning, and the rotation of the intermediate transfer rotator is stopped. Thereafter, when the conveyance of the recording medium is detected, the intermediate transfer rotator is detected. Control means for actuating the recording medium pressing means to press the recording medium against the intermediate transfer rotator and to rotate the intermediate transfer rotator in order to transfer the multi-toner image to the recording medium. Suggest that the image forming apparatus.

Further, in order to achieve the third object of the present invention, the toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface and the outer peripheral surface rotate while being in contact with the toner image carrier. Between the intermediate transfer rotator and toner images of different colors, which are sequentially formed on the toner image carrier, are transferred so as to form a multiple toner image, and the multiple toner images on the intermediate transfer rotator are recorded on the recording medium. A toner heating unit that melts the multiple toner image on the intermediate transfer rotator so that the multiple toner image on the intermediate transfer rotator can be melt-transferred to the recording medium, and a recording medium transport that transports the recording medium to transfer the multiple toner image on the intermediate transfer rotator. Means, a recording medium pressing means for pressing the recording medium on which the multiple toner image is transferred to the intermediate transfer rotator, a means for heating the recording medium pressing means, and a temperature detecting means for detecting the temperature of the recording medium pressing means. After the start of the image forming process, when the temperature temperature detecting means for detecting is a predetermined value or more,
The recording medium pressing means is operated to press the recording medium against the intermediate transfer rotator so that the multiple toner image on the intermediate transfer rotator can be transferred onto the recording medium, and the temperature detected by the temperature detecting means is lower than a predetermined value. If it is low, an image forming apparatus including a control unit that puts the recording medium pressing unit into a standby state without operating it is proposed.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

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

In the figure, reference numeral 1 denotes a drum-shaped photosensitive member, which constitutes an example of the constitution of a toner image holding member in which toner images of different colors are sequentially formed on the outer peripheral surface. is there. Reference numeral 2 denotes a drum-shaped intermediate transfer rotary member, and 3 denotes an endless conveyor belt. As the photoconductor 1,
For example, an organic photoconductor that is relatively excellent in pressure resistance and heat resistance is used.

The photoconductor 1, the intermediate transfer rotator 2, and the conveyor belt 3 are each driven to rotate in the direction of the arrow in the figure. Of these, the intermediate transfer rotator 2 has an outer peripheral surface. It rotates while being in contact with the photoconductor 1, and in the meantime, it is sequentially formed on the photoconductor 1 on the surface of the intermediate transfer rotator 2.
Toner images of different colors are transferred in an overlapping manner. In this way, multiple toner images are formed on the intermediate transfer rotator 2.

The conveyor belt 3 constitutes one example of a recording medium conveying means for conveying the recording medium in order to transfer the multiple toner images on the intermediate transfer rotator 2 to the recording medium.

As the photosensitive member 1 starts to rotate, its surface is uniformly charged by the charging charger (scorotron charger) 4. The laser optical system 5 emits laser light 6 modulated according to an image signal, and the laser light 6 causes
By performing optical writing scanning (image exposure) on the surface of the photoreceptor 1 after charging, a predetermined electrostatic latent image is formed on the surface. The laser optical system 5 is composed of, for example, a semiconductor laser, a rotary polygon mirror, an fθ lens, etc., which are not shown, and a laser modulation circuit controls light emission of the semiconductor laser according to an image signal.

A yellow developing device 7Y, a magenta developing device 7M, a cyan developing device 7C, and a black developing device 7B, which are arranged in series in the circumferential direction of the photoconductor 1, are arranged opposite to each other. Each of these developing devices accommodates a two-component developer in which toners of different colors of yellow, magenta, cyan, and black are mixed with a carrier. For example, the yellow developing device 7Y contains a two-component developer in which a high-resistance non-magnetic yellow toner and a magnetic carrier are mixed. The other developing devices also contain a two-component developer in which a magnetic carrier is mixed, although the color of the toner is different. The toner of each color preferably has a particle size of about 5 μm or less so that the resolving power is high, the gradation reproducibility by area gradation is good, and the swelling of the toner images due to superposition is as small as possible. .

For example, the yellow developing device 7Y has a structure as shown in FIG. That is, this developing device
It has a magnet 8 inside and is composed of a non-magnetic sleeve 9 that conveys the developer to the developing area by rotating it, and a developer regulating plate 11 that regulates the amount of the developer conveyed onto the sleeve. The yellow developer is a stirring member 12, 1.
3, 14 is sufficiently agitated, during which the yellow toner comes into contact with the carrier (in this embodiment the toner is negatively charged). The magnetic field formed on the sleeve 9 is changed by the circumferential movement of the magnet 8 in the sleeve, and whether or not the developer is supplied to the developing area is controlled.

The other developing devices are also constructed in the same manner. When the selected developing device develops, a magnetic field for supplying the developer is formed on the sleeve, the sleeve rotates, and at the same time, the sleeve rotates. A developing bias (about -300 to -1000 V) is applied to the unit 9 by the bias voltage power source E ₁ .

In the developing area, due to the electric field formed between the photoreceptor 1 and the photoreceptor 1, only the toner is attracted to the electrostatic latent image on the photoreceptor and adheres to the photoreceptor 1. That is, the toner T adhered to the carrier C on the sleeve 9 adheres to the exposed portion on the photoconductor 1 exposed to the laser light. In this way, the electrostatic latent image on the photoconductor 1 is visualized as a toner image, but in a developing device that is not selected, the developer regulating plate prevents the developer from moving, and the developing area The developer is not conveyed to the.

When a bias is applied to the sleeve in which the developer is not conveyed to accelerate the development, it is possible to prevent the toner of the toner image developed by another developing device from mixing into the developing device, resulting in color turbidity. The effect that is suppressed is obtained.

Returning to FIG. 1, it is desirable that the intermediate transfer rotator 2 has appropriate elasticity so that a sufficient contact area and uniform pressure can be obtained with the photosensitive member 1. Further, the surface thereof has adhesiveness to the toner at room temperature, and further has a characteristic of facilitating separation of the melted and fluidized toner in order to efficiently transfer the toner to the recording medium, that is, heating. In this state, the toner shows releasability. For example, the surface of the intermediate transfer rotator 2 exhibits adhesiveness to toner at room temperature,
It is composed of silicone rubber or the like that exhibits releasability to the toner when heated.

A specific example of the intermediate transfer rotator 2 is shown in FIG.
The following can be mentioned. That is, it has a thickness of 500 to 5000 μm and a rubber hardness of 30 to 30 on a supporting drum 15 made of a rigid material such as aluminum.
80 degree elastic layer 16, conductive layer 17 made of polyimide having carbon black dispersed therein and having a thickness of 30 to 300 μm,
A sheet-like body composed of an insulating adhesive layer 18 of silicone rubber having a thickness of 10 to 300 μm is adhered with the elastic layer 16 inside. The sheet-shaped body serves as an intermediate transfer medium, but it is also possible to fix only one end of the sheet-shaped body to the support drum 15 without adhering the sheet-shaped body to the support drum 15.

The surface of the intermediate transfer rotator 2 preferably has irregularities smaller than the substantially minimum particle size of the toner in order to prevent transfer omission due to the loss of adhesion with the photoreceptor 1. . For example, when the substantial minimum particle size of the toner is 5 μm, the unevenness of the intermediate transfer rotator 2 is preferably 5 μm or less. The conductive layer 17 is insulated from the support drum 15, and when the toner image is transferred from the photoconductor 1 to the intermediate transfer rotator 2, the conductive layer 17 receives a predetermined transfer bias due to the bias voltage E _2. Is applied.

Inside the intermediate transfer rotary member 2, a heater 19 separate from the rotary member is immovably provided. Heater 1
A halogen lamp or the like is used as 9, so that the toner of the multiple toner image adhering to the surface can be heated from the inside of the intermediate transfer rotator 2 through the above-mentioned sheet-like body. At this time, the intermediate transfer rotator 2 is not always
It is not necessary to uniformly heat the whole, and it is sufficient that the temperature is equal to or higher than a certain temperature at the position where the transfer to the recording medium is performed. When the toner image is transferred onto the recording medium, the toner is heated above the softening point so that it is easily melted.

The intermediate transfer rotator 2 is rotatably driven by a drive control means, which will be described later, so that its rotational speed can be switched.

The conveyor belt 3 is made of a material having heat insulation and flexibility, and for example, a polyimide base coated with a silicone resin is used. This belt 3
Is driven by being wound around a plurality of rollers from the inside.

Among the rollers provided inside the conveyor belt 3, a heater 25 is provided inside the roller 21 facing the intermediate transfer rotor 2, and the heater 25 keeps the temperature of the transfer area at a predetermined value. It is configured to The roller 21 presses the conveying belt portion wound around the roller 21 from the inside thereof to press the belt portion against the intermediate transfer rotator 2, so that the recording medium on the conveying belt 3 is moved to the intermediate transfer rotator 2 as described later. It functions as a pressure roller that makes pressure contact. Pressure roller 21 and lower roller 22
Is connected to each end of the connecting rod 23 rotatably, and a solenoid 24 is connected to the connecting rod 23.

The surface temperature of the pressure roller 21 is detected by a temperature detecting means, and as the means, a thermistor (not shown) in contact with the surface of the pressure roller 21 is used in this example.

A spring (not shown) is interposed between the shafts of the intermediate transfer rotator 2 and the pressure roller 21, and the belt portion wound around the pressure roller 21 is rotated by the force of the spring. It is in pressure contact with body 2. On the other hand, when the solenoid 24 is excited, the connecting rod 23 is pulled, and the belt portion thereof is separated from the intermediate transfer rotary member 2 as shown by the broken line in FIG. In any case, the belt portion comes into contact with or separates from the intermediate transfer rotator 2 according to a predetermined sequence. Solenoid 24
Instead of this, the pressure roller 21 may be brought into contact with and separated from the intermediate transfer rotator 2 by a driving device such as a roller contact / separation motor.

On the other hand, the photosensitive member 1 and the intermediate transfer rotary member 2
In the meantime, a spring (not shown) is interposed between these shafts, and in accordance with a predetermined sequence, the operation of a contact / separation motor (not shown) causes them to be separated from each other or pressed against each other by the action of a cam or the like. It is supposed to do.

Here, toner images of different colors are sequentially formed on the photoconductor 1, and these toner images are superposed and transferred on the intermediate transfer rotator 2 and then on the intermediate transfer rotator 2. Multiple toner images are obtained. At this time, the conveyor belt 3 is separated from the intermediate transfer rotator 2 as indicated by a broken line in FIG. 1 so that the toner image on the intermediate transfer rotator 2 is not disturbed. After the toner image is transferred onto the intermediate transfer member 2 in an overlapping manner, the surface of the photosensitive member 1 is cleaned by the cleaning device 10.

The transfer paper 26, which is an example of a recording medium, is fed from the left side of FIG.
Prior to being conveyed by the pair of heating rollers 27.
While passing through (the whole of which is heated to about 50 ° C. to 180 ° C.), it is preheated. By heating the transfer paper 26 with the conductive heat from the heating roller 27 which is in contact with the transfer paper 26 in this manner, the transfer paper 26 can be brought to the target temperature in a short time. The heating roller 27 is a hollow rigid roller coated with a heat-resistant material such as silicone rubber or Teflon resin, and a heater (not shown) such as a halogen lamp is provided therein.

The transfer paper 26 which has been preheated by the heating roller 27 is sent toward the conveyor belt 3, and while being conveyed by the conveyor belt 3, the pressure roller 2
It is pressed onto the intermediate transfer rotator 2 by the force of 1, and the above-mentioned multiple toner image is transferred onto the transfer paper 26. That is, at the time of this transfer, the conveyor belt 3 is pressed against the intermediate transfer rotator 2 as shown by the solid line in FIG.
6 is pressed against the intermediate transfer rotator 2 and the multiple toner image is transferred onto it.

An example of a recording medium conveyance detecting means for detecting that the recording medium is conveyed upstream of the facing portion of the pressure roller 21 and the intermediate transfer rotator 2 in the conveying direction of the transfer paper 26. A transfer paper detection sensor 41 is provided.

By heating the intermediate transfer rotator 2 by the heater 19, the toner of the multiple toner image on the intermediate transfer rotator 2 is melted and the surface releasability of the intermediate transfer rotator is improved. The toner image on the surface of the intermediate transfer rotator is transferred to the transfer paper by raising the toner so that the toner is easily separated from the surface. At this time, another heater 25
When the transfer paper 26 passing by is heated, the toner of the toner image in a melted state is transferred to the transfer paper, penetrates into the fibers of the paper, and is fixed. The melting state of the toner at this time is preferably a state in which the toner is not powder, but can be melted and moved a little, that is, a semi-molten state, and the viscosity is not excessively low.

A conveyor belt 3 having a heat generating layer is used, and a predetermined voltage is applied to the conveyor belt 3 to generate heat, so that the transferred transfer paper 26 is preheated. good. In this way, if the transfer paper 26 is heated before the transfer, the heat-melting transfer and the fixing can be efficiently performed in combination with the effect of heat application by the heater 25, and the recording speed can be increased. .

The portion of the intermediate transfer rotator 2 that has transferred the multiple toner images onto the transfer paper 26 is cleaned by the cleaning device 40, and the toner images are transferred from the photoreceptor 1 again.
At this time, the surface of the intermediate transfer rotator 2 is already cooled and returns to room temperature or a temperature close to it, the adhesiveness of the surface is increased, and the toner image is efficiently transferred from the photoreceptor 1.

A blower (not shown) blows cool air to the surface of the intermediate transfer rotator 2 which has finished transferring the multiple toner images onto the transfer paper 26 to forcibly cool it, so that the temperature can be more reliably kept at room temperature or a temperature close thereto. To increase its stickiness,
It is desirable that the toner image be easily transferred from the photoconductor 1.

The basic structure of the image forming apparatus shown in FIGS. 1 to 3 has been described above. An example of the image forming process performed by the image forming apparatus will be described below with reference to the flow chart shown in FIG. However, other configurations will be clarified. In the flowchart, "B
“R” refers to the intermediate transfer rotary member 2 (the same applies to FIG. 5 described later).

In the initial state, the photosensitive member 1 is separated from the intermediate transfer rotary member 2, and the conveyor belt 3 is also separated from the intermediate transfer rotary member 2. Each element including these is in a non-operating state, and the operation is sequentially started as follows.

(0) First, the temperature control system of the pressure roller 21 is operated. (B1) With the thermistor described above, the pressure roller 21
Of the temperature is detected, and if it exceeds a predetermined temperature, the process proceeds to the previous step, and if the pressure roller 21 is lower than the predetermined temperature, it enters a standby state. (1) The photoconductor 1 and the intermediate transfer rotator 2 are pressed against each other. (2) The photoconductor 1 and the intermediate transfer rotator 2 start high-speed rotation in the arrow direction in FIG. 1 at the same constant surface linear velocity (for example, 300 mm / s). (3) The charging charger 4 starts discharging to uniformly charge the photoconductor 1 and set its surface potential to about −800V. (4) The laser optical system 5 scans the surface of the photoconductor 1 with the laser light 6 modulated based on the image signal, and forms an electrostatic latent image on the photoconductor. The electrostatic latent image is formed such that a portion irradiated with laser light (surface potential is about -100V) is a toner adhesion portion and an unexposed portion (surface potential is about -800V) is a background portion.

(5) The electrostatic latent image is developed by the yellow developing device 7Y. In the developing devices 7M, 7C, 7B other than yellow, a magnetic field is formed so that the developer is not conveyed. At that time, the developing bias applied to the sleeve 9 of the yellow developing device 7Y is -600 V, and the reversal developing is performed. In this way, a yellow toner image is formed on the photoconductor 1. (6) The portion of the photoconductor 1 on which the yellow toner image is formed reaches the position where it comes into pressure contact with the intermediate transfer rotator 2. Between the photoconductor 1 and the intermediate transfer rotator 2 is 0.3 to 3.0.
The pressure of kg / cm is applied, and the conductive layer 1 of the intermediate transfer rotator 2
A transfer bias of +0.5 to 5 kv is applied to 7.

An electric field is formed at the nip portion (contact portion) between the photosensitive member 1 and the intermediate transfer rotator 2, and the toner is transferred from the photosensitive member 1 to the intermediate position according to the electric field and the adhesiveness of the surface of the intermediate transfer rotator 2. It is transferred to the transfer rotating body 2. At that time, at the contact portion between the photoconductor 1 and the intermediate transfer rotator 2, the toner is sandwiched between them and hardly moves, and the electrostatic transfer due to the electric field formed and the adhesive force from the intermediate transfer rotator 2 cause the intermediate transfer. The adhesive force with the rotating body 2 becomes large, and the transfer is performed on the intermediate transfer rotating body with almost no movement in the interface direction.
A cleaning device 10 acts on the rotating photoconductor, and the device 10 cleans the surface of the photoconductor after the transfer of the yellow toner. Further, the surface of the photoconductor 1 after the toner image transfer is subjected to a neutralizing action by a neutralizer (not shown).

(7) (8) (9) Steps (4)-
The process (6) is executed by selecting the magenta developing device 7M instead of the yellow developing device 7Y. In transferring the toner image to the intermediate transfer rotator 2, similarly, a bias is applied to the conductive layer 17, and the magenta toner image is transferred onto the yellow toner image. In the process of transferring the toner image from the photoconductor 1, the magenta toner is mostly sandwiched between the photoconductor 1 and the intermediate transfer rotator 2 even on the region of the intermediate transfer rotator 2 where the yellow toner exists. There is no freedom of movement, and the electrostatic force of the electric field increases the adhesion force to the intermediate transfer rotator 2. When the photosensitive body 1 and the intermediate transfer rotator 2 are separated from each other, the intermediate transfer rotator is separated from the photosensitive body 1. Adhere on 2. (10) to (15) Similarly, (4) to (6) are executed with cyan and black toners, respectively, and a four-color multiple toner image is formed on the intermediate transfer rotator 2.

In this way, the toner images of different colors sequentially formed on the outer peripheral surface of the photoconductor 1 are transferred to the intermediate transfer rotator 2.
The toner images are transferred and superposed on each other so as to form a powdery multiple toner image. The transfer is performed while the outer peripheral surface of the intermediate transfer rotator 2 rotates while being in contact with the photoconductor 1.

(16) The discharge from the charging charger 4 is stopped. (17) The photoconductor 1 separates from the intermediate transfer rotator 2. (18) The rotation speed of the intermediate transfer rotator 2 becomes slower than before (for example, the surface linear velocity becomes 100 mm / s). (19) At the same time, the conveyor belt 3 starts to rotate at a linear velocity substantially equal to the surface linear velocity of the intermediate transfer rotator 2 in order to convey the transfer paper 26.

(B2) The transfer paper detection sensor 41 detects the presence or absence of the transfer paper 26. That is, the sensor 41 detects the optical reflectance on the conveyor belt 3 at a predetermined time, and when it is equal to or larger than the predetermined value, it is determined that the transfer paper 26 has been conveyed, and the process proceeds to step (22) and thereafter. When the reflectance is smaller than the predetermined value, it is determined that the transfer sheet is not conveyed, (20) a warning is displayed on the display unit, and (21) each drive unit is stopped. When the conveyance of the transfer sheet is not detected by the transfer sheet detection sensor 41, a warning is issued to inform the operator of the fact and the rotation of each element including the intermediate transfer rotating body 2 is stopped. In the present example, the display section constitutes an example of a warning generation unit that issues a warning when the recording medium conveyance detection unit does not detect the conveyance of the recording medium.

(B3) When the operator processes the cause that the transfer sheet is not conveyed and restarts, the process is repeated from step (18). After the transfer sheet detection sensor 41 detects that the transfer sheet 26 has been conveyed, the rotation of the intermediate transfer roller 2 is stopped after the rotation of the intermediate transfer roller 2 is stopped based on the fact that the transfer sheet is not conveyed. It will resume.

(22) Timing at which the multicolor multi-toner image of the intermediate transfer rotator 2 moves as the intermediate transfer rotator 2 rotates and the leading edge of the image is transferred to the leading edge of the transfer paper 26. Then, the transfer paper is conveyed by the conveyor belt 3. The intermediate transfer rotator 2 and the conveyor belt 3 are sandwiched by the pressure roller and brought into a pressure contact state with a pressure of 0.3 to 3.0 kg / cm. By operating the solenoid 24 or other driving device, the pressure roller 21 is raised to press the transfer paper 26 against the intermediate transfer rotating body 2. As described above, the pressure roller 21 constitutes an example of a recording medium pressing unit that presses the recording medium on which the multiple toner images are transferred to the intermediate transfer rotating body.

When the multi-toner image on the intermediate transfer rotator 2 is in contact with the transfer paper 26, the toner of the multi-toner image is melted, and the photoconductor is placed on the intermediate transfer rotator 2. The heater 19 is turned on at a timing that does not prevent the powdery toner of each color from being sequentially transferred from 1 to form a powdery multiple toner image on the intermediate transfer rotator 2. Moreover, at this time, the pressure roller 21 is heated by the internal heater 25, so that the intermediate transfer rotator 2
The upper multi-toner image is heated from the inside of the intermediate transfer rotator 2 and from the pressure roller 21 side via the transfer paper 26, and easily becomes a melted state, and flows on the transfer paper 26 to flow into the fibers of the paper. Permeate into.

At the same time, the toner image transferred onto the transfer paper 26 has releasability between itself and the intermediate transfer rotator 2, so that it is fixed on the intermediate transfer rotator 2 without being offset. That is, the secondary transfer and the fixing are simultaneously performed. In this example, the transfer paper 26 is preheated by the heating roller 27 prior to this process, so that the above operation is performed more reliably.

As described above, the heaters 19 and 25 on the intermediate transfer rotator 2 can melt-transfer the multiple toner images transferred from the photoconductor 1 onto the intermediate transfer rotator 2 onto the transfer paper 26. An example of a toner heating unit that melts the multiple toner image is configured. The heater 25 also constitutes a means for heating the recording medium pressing means.

(23) The pressure roller 21 separates from the intermediate transfer rotary member 2. (24) The surface of the intermediate transfer rotator 2 is cleaned by the cleaning device 40, the temperature is lowered by natural cooling or forced cooling, the adhesiveness is shown again, and the toner image is ready for the next toner image transfer. (B4) When subsequently forming a recorded image, the process is repeated from the process of (1). (25) When an image is not formed, each driving part stops and a series of image processes ends.

In the image forming apparatus described above, the photoconductor 1
The toner image is transferred from the intermediate transfer rotor 2 to the intermediate transfer rotor 2, and this process is repeated to form a multiple toner image on the intermediate transfer rotor 2. The multiple toner images are melted and transferred to the transfer paper 26. Scattering can be suppressed, and dot and line reproducibility, gradation reproducibility, and resolution can be improved. Moreover, the surface linear velocity of the intermediate transfer rotator 2 when the toner image is transferred from the photoconductor 1 to the intermediate transfer rotator 2 is more melted and transferred from the intermediate transfer rotator 2 to the transfer paper 26. Since the rotation of the intermediate transfer rotator 2 is controlled so that it becomes slower, the speed of melt transfer of the multiplex toner image from the intermediate transfer rotator 2 to the transfer paper 26 is made slower than other process speeds. It is possible to lengthen the time for the toner image to pass through the portion of the intermediate transfer rotator 2 that contacts the transfer paper 26.

For this reason, the heat of the toner melted on the intermediate transfer rotator 2 is taken away by the transfer paper 26 during the melt transfer of the multiple toner image onto the transfer paper 26, and the toner is transferred onto the transfer paper 26. You can prevent the problem that it hardens quickly. That is, the multiple toner images can be melt-transferred onto the transfer paper 26 without trouble even if the intermediate transfer rotor 2 and the pressure roller 21 are not heated to a high temperature by the heaters 19 and 25.
The amount of heat energy consumed can be reduced.

In addition, since the intermediate transfer rotator can be cooled for a long time after the intermediate transfer rotator leaves the transfer portion during melt transfer of the multi-toner image, the temperature of the intermediate transfer rotator 2 can be sufficiently lowered and the adhesion thereof can be reduced. Since the intermediate transfer rotator 2 at high temperature can be prevented from coming into contact with the photoconductor 1, it is possible to prevent the problem that the photoconductor 1 is adversely affected by heat.

Furthermore, when the toner image is transferred from the photoconductor 1 to the intermediate transfer rotator 2, the surface linear velocity of the intermediate transfer rotator 2 can be increased, so that the problem of slow recording speed can be prevented.

The toner heating means may be constituted by only the heater 19 without providing the heater 25, or the toner may be heated by a heater or a radiant energy applying lamp for applying heat from the outside to the multiple toner image on the intermediate transfer rotator. Even when the means is configured, the above effect can be obtained as it is.

In this way, the multiple toner images can be efficiently melt-transferred onto the transfer paper 26 and fixed with a small amount of heat energy without lowering the recording speed.

The photoconductor 1 and the intermediate transfer rotator 2 may be kept in contact with each other at all times, but in this example, when the toner image on the photoconductor 1 is transferred onto the intermediate transfer rotator 2, 1 contacts the intermediate transfer rotator 2, but when the multiple toner images are collectively melt-transferred from the intermediate transfer rotator 2 to the transfer paper,
The photoconductor 1 is separated from the intermediate transfer rotator 2 and is in a non-contact state. That is, the photosensitive member 1 and the intermediate transfer rotator 2 are brought into pressure contact with each other only when a multiple toner image of powdery toner is formed on the intermediate transfer rotator 2, and they are separated from each other otherwise. With such a configuration, it is possible to prevent a problem that an excessive load is applied to the photoconductor 1 and the intermediate transfer rotary member 2, and it is possible to eliminate a problem that the photoconductor 1 is deteriorated by the action of heat. When the photoconductor 1 performs the contacting / separating operation with respect to the intermediate transfer rotator 2, the charging charger 4, the developing devices 7Y, 7M, 7C, 7B, the cleaning device 10 and the like around the photoconductor 1 also operate together with the photoconductor 1. Moreover, it is desirable to assemble them integrally.

After the multi-color multi-toner image is formed on the intermediate transfer rotator 2, if the transfer paper 26 is not conveyed, a warning is issued and the operation is interrupted. When conveyed, the operation is restarted from the process of transferring the multiple toner images from the intermediate transfer rotator 2 to the transfer paper 26. That is, when the conveyance of the transfer paper 26 is detected by the transfer paper detection sensor 41, the rotation of the intermediate transfer rotary body 2 is performed so that the multiple toner images on the intermediate transfer rotary body 2 can be transferred onto the transfer paper 26. And the pressure roller 21 is operated to press the transfer paper 26 against the intermediate transfer rotator 2. On the contrary, when the transfer paper 26 is not detected to be conveyed by the transfer paper detection sensor 41, the transfer paper 26 is operated so that the display unit gives a warning, and the rotation of the intermediate transfer rotator 2 is stopped. When the conveyance of is detected, the pressure roller 21 is operated to press the transfer paper 26 against the intermediate transfer rotator 2 in order to transfer the multiple toner images on the intermediate transfer rotator 2 to the transfer paper 26.
Moreover, the intermediate transfer rotator 2 is rotated. With such a configuration, the process (time, energy consumption, consumable materials, etc.) up to the formation of the multiple toner image is not wasted, and the cleaning of the intermediate transfer rotator 2 is not burdened.
Images can be output immediately after the device is properly treated.

In the above process, for example, when a magenta toner image is transferred onto the intermediate transfer rotator 2 on which a yellow toner image exists, the transfer electric field is weakened by the charge of the yellow toner and the magenta toner is weakened. Is susceptible to Coulomb repulsion, and the yellow toner acts as a spacer, weakening the adhesion between the photoconductor 1 and the intermediate transfer rotator 2.

Therefore, it is preferable to set the conditions (transfer bias, transfer pressure) of the primary transfer step (6) for each color of toner. As an example, yellow toner transfer is +200 V (condition 1), magenta toner transfer is +500 V (condition 2), cyan toner transfer is +800 V (condition 3), and black toner transfer is +.
1200V (condition 4) is applied. This way,
It is possible to weaken the electrical influence of the toner already transferred onto the intermediate transfer rotator 2 and gradually increase the transfer pressure to enhance the adhesion between the photoconductor 1 and the intermediate transfer rotator 2.

The photoconductor 1 and the intermediate transfer rotator 2, and the intermediate transfer rotator 2 and the pressure roller 21 can be pressed and separated according to the sequence. Especially, in order to prevent the toner from being directly transferred to the surface of the conveyor belt 3,
When the belt 3 does not hold the transfer paper 26, the pressure roller 21 is lowered so that the intermediate transfer rotator 2 and the conveyor belt 3 are not contacted. In addition, the heating roller 27,
The heating roller and the transport belt 3 may be provided so as to face the transport belt 3, but in this case, the heating roller and the transport belt 3 are
It is desirable to control the separation so that they are not in contact with each other except when they rotate and hold the transfer paper 26.

In the image forming process shown in FIG. 4, the temperature detecting means including a thermistor detects the temperature of the pressure roller 21, and the heater 25 is controlled to be turned on and off according to the result. When the temperature of the pressure roller 21 becomes equal to or higher than a predetermined temperature at the start of the operation, an actual image forming process is started, and when the pressure roller 21 is lower than the predetermined temperature, the apparatus is kept in a standby state. However, according to this configuration, as described above in the section of the related art, the warming-up time is required until the pressure roller 21 is heated to the same degree before starting the image forming process.

Therefore, regardless of the temperature of the pressure roller 21, the image forming process is first started, and after the process is started, the temperature of the pressure roller 21 is detected, and the temperature becomes equal to or higher than a predetermined value. If the temperature is lower than a predetermined value, the apparatus is configured to be in a standby state when the temperature is lower than a predetermined value. If the pressure roller 21 is actually transferred after the start of the image forming process. The temperature of the pressure roller 21 can be increased by using the time until the operation for pressing the paper 26 is started, and the waiting time of the operator can be reduced or eliminated.

A specific example of performing such an operation by the image forming apparatus shown in FIGS. 1 to 3 will be described with reference to the flowchart shown in FIG. This operation is shown in FIG.
Since many parts overlap with the operation shown in (1), the overlapping parts will be briefly described. Further, in FIG. 5, the operation relating to the switching of the rotation speed of the intermediate transfer rotating body 2 is omitted.

(0) The temperature control system of the pressure roller 21 is activated. (1) The photoconductor and the intermediate transfer rotator are brought into pressure contact with each other. (2) The photoconductor and the intermediate transfer rotator are rotated at the same constant linear velocity in the directions of the arrows in FIG. (3) Turn on the charger 4 to start discharging,
The photoconductor 1 is uniformly charged. (4) The laser optical system 5 scans the surface of the photoconductor with the laser beam 6 modulated based on the image signal, and forms an electrostatic latent image on the surface. (5) The electrostatic latent image is developed by the yellow developing device 7Y. In the developing devices 7M, 7C, 7B other than yellow, a magnetic field is formed so that the developer is not conveyed. (6) A transfer bias voltage is applied to the conductive layer 17 of the intermediate transfer rotator. The cleaning device 10 acts on the rotating photoconductor, and the device 10 cleans the surface of the photoconductor after the transfer of the yellow toner image.

(7) (8) (9) Steps (4)-
The process (6) is executed by selecting the magenta developing device 7M instead of the yellow developing device 7Y. Similarly, in the transfer of the toner image onto the intermediate transfer rotator 2, a bias voltage is applied to the conductive layer 17 of the intermediate transfer rotator 2, and the magenta toner image is transferred onto the yellow toner image. (10) to (15) Similarly, the same processes as (4) to (6) are executed with cyan and black toners, respectively, and a multi-color toner image of four colors is formed on the intermediate transfer rotator 2.

(16) The charging charger 4 is turned off and its discharge is stopped. (17) The photoconductor 1 separates from the intermediate transfer rotator 2. (B1) The output from the temperature sensor that detects the temperature of the pressure roller 21, which is the thermistor in this example, is determined. If the output is greater than or equal to the predetermined value, the process proceeds to step (19). (18) If the temperature value is lower than the predetermined value, the fact is displayed on the display unit of the operation panel of the image forming apparatus, and the image forming apparatus is put in the standby state. (19) In order to convey the transfer paper 26 in parallel, the conveyor belt 3 is rotationally driven at a linear velocity substantially equal to that of the intermediate transfer rotator 2.

(B2) The transfer paper is the transfer paper detection sensor 4
If the presence or absence thereof is detected by 1 and it is determined that the transfer sheet has been conveyed, the process proceeds to step (22) and thereafter.
When it is determined that the transfer sheet is not conveyed, (20) a warning is displayed on the display unit, and (21) each drive unit is stopped. (B3) When the operator processes the cause that the transfer sheet is not conveyed and restarts, the process is repeated from the determination (B1). (22) The intermediate transfer rotator 2 and the transport belt 3 are pressed against each other by the pressure roller 21 with the transported transfer paper 26 interposed therebetween. As a result, the multiple toner images on the intermediate transfer rotator 2 are secondarily transferred and fixed on the transfer paper 26.

(23) The pressure roller 21 is separated from the intermediate transfer rotator 2. (24) The surface of the intermediate transfer rotator 2 is cleaned by the cleaning device 40. (B4) When subsequently forming a recorded image, the process is repeated from the process of (1). (25) When the image is not continuously formed, each driving portion is stopped and this series of image forming processes is brought to an end state.

As described above, after starting the image process,
The thermistor which is an example of the temperature detecting means is a pressure roller 21.
Is detected, and if the detected temperature is equal to or higher than a predetermined value, the multiple toner image on the intermediate transfer rotator 2 is transferred to the transfer paper 2
6, the pressure roller 21 is operated to press the transfer sheet against the intermediate transfer rotator 2, and when the temperature detected by the temperature detecting means is lower than a predetermined value, the pressure roller 21 is moved. Since the stand-by state is set without operating, the apparent warm-up time of the image forming apparatus can be saved and the time until the first image output can be shortened. This is possible only by using the intermediate transfer rotary member.

The above process can be carried out by a control system as outlined in FIG. That is, a command is transmitted from the control unit to each terminal while monitoring the state of the device via the port. In the control unit, the CPU executes the control program, and the charger, the laser optical system, each developing device, the main motor (which drives the intermediate transfer rotator and can be switched to the second speed), the conveyance motor, the solenoid, each contact / separation motor, and the display It controls the parts, the cleaning device, the heater in the pressure roller, and the like.

The photoconductor, the intermediate transfer rotator, and the conveyor belt are rotationally driven by independent drive sources or common drive sources. A main motor that drives the intermediate transfer rotator rotates the intermediate transfer rotator at a speed according to a clock pulse input from the outside. Alternatively, it may be rotated at a speed controlled by a current value input from the outside.
As described above with reference to FIG. 4, the main motor rotates the intermediate transfer rotator slowly during the process of transferring the multicolor toner image from the intermediate transfer rotator to the transfer paper, and quickly at other times.

As can be understood from the above description, in this embodiment, the surface linear velocity of the intermediate transfer rotary member is changed from the toner image holding member to the intermediate transfer rotary member by the control unit and the main motor shown in FIG. The drive control means for rotationally driving the intermediate transfer rotator is configured so that the time when the multiple toner images are transferred from the intermediate transfer rotator to the recording medium is slower than the time when the intermediate transfer rotator is transferred.

Similarly, in this embodiment, when the toner image on the toner image holding member is transferred onto the intermediate transfer rotating member by the control unit and the photosensitive member contact / separation motor shown in FIG. 6, the toner image holding member and the intermediate transfer rotating member are rotated. A contact / separation unit is configured to bring the toner image holder and the intermediate transfer rotator out of contact with each other when the multiple toner images are transferred from the intermediate transfer rotator to the recording medium by contacting the body.

Similarly, in this example, the recording medium conveyance detecting means detects the conveyance of the recording medium by the control section, the main motor, the pressure roller contact / separation solenoid (or a driving device such as a motor) shown in FIG. In this case, in order to transfer the multi-toner image on the intermediate transfer rotator onto the recording medium,
When the rotation of the intermediate transfer rotator is continued and the recording medium pressing means is operated to press the recording medium against the intermediate transfer rotator, and the conveyance of the recording medium is not detected by the recording medium conveyance detecting means, a warning means Is activated, the rotation of the intermediate transfer rotator is stopped, and when the conveyance of the recording medium is detected, the multiple toner image on the intermediate transfer rotator is transferred to the recording medium. In order to do so, the control means is configured to operate the recording medium pressing means to press the recording medium against the intermediate transfer rotator and rotate the intermediate transfer rotator.

In the same manner, in this example, the temperature detecting means operates the recording medium pressing means after the image forming process is started by the control unit and the pressure roller contact / separation solenoid (or a driving device such as a motor) shown in FIG. When the detected temperature is equal to or higher than a predetermined value, the recording medium pressing unit is operated to press the recording medium against the intermediate transfer rotator so that the multiple toner image on the intermediate transfer rotator can be transferred to the recording medium. At the same time, when the temperature detected by the temperature detecting means is lower than a predetermined value, the control means is configured to put the recording medium pressing means into a standby state without operating it.

As described above, the four color toner images are transferred to the intermediate transfer rotator 2.
Although the example of forming a toner image has been described above, the present invention is not limited to this, and when forming a toner image of one to three colors, the same process can be performed. At that time, transfer / fixing conditions such as temperature may be changed according to the number of colors.

Further, a belt-shaped member may be used as the toner image holding member or the intermediate transfer rotary member instead of the drum-shaped member, or the recording medium conveying means may be constituted by a drum or a conveying roller.

[0093]

According to the image forming apparatus of the present invention, the speed of the intermediate transfer rotary member when transferring and fixing the multiple toner images from the intermediate transfer rotary member to the recording medium is slower than other process speeds. So, while maintaining a high recording speed,
The multiple toner images can be simultaneously fused and fixed on the recording medium with a small amount of energy. Further, unnecessary heating of the toner image carrier is eliminated.

According to the image forming apparatus of the second aspect,
It is possible to reduce the load applied to the toner image holding member and the intermediate transfer rotating member, and it is possible to more reliably prevent the problem of giving unnecessary heat to the toner image holding member.

According to the image forming apparatus of claim 3,
When the recording medium is not conveyed, the operation is interrupted, and when the recording medium is conveyed properly thereafter, the operation can be restarted from the process of transferring the recording medium overlapping toner image from the intermediate transfer rotator. The process (time, energy consumption, consumables, etc.) up to the formation of multiple toner images is not wasted, and the cleaning of the intermediate transfer rotator is not burdened, and an image can be output immediately after the proper treatment of the apparatus.

According to the image forming apparatus of claim 4,
By starting the image forming process regardless of the temperature of the member that presses the recording medium against the intermediate transfer rotator, and setting the standby operation before the multiple toner image transfer to the recording medium, the apparent warm-up time is saved, The time until the first image output can be shortened.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing one of developing units provided in the image forming apparatus.

FIG. 3 is a partially enlarged cross-sectional view of an intermediate transfer rotary member.

FIG. 4 is a diagram showing a flowchart corresponding to an embodiment of the present invention.

FIG. 5 is a diagram showing a flowchart of another example.

FIG. 6 is a block diagram of a control system of each embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor as a toner image carrier 2 Intermediate transfer rotator 3 Conveyor belt as a conveying means 26 Transfer paper as a recording medium

Claims (4)

[Claims] 1. A toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface, and a toner image carrier on the toner image carrier while the outer peripheral surface rotates while being in contact with the toner image carrier. , An intermediate transfer rotator on which toner images of different colors are transferred so as to form a multiple toner image, and an intermediate transfer rotator on the intermediate transfer rotator so that the multiple toner images on the intermediate transfer rotator can be melt-transferred to a recording medium. The toner heating means for melting the multiplex toner image and the surface linear velocity of the intermediate transfer rotator cause the multiplex toner image to be transferred from the intermediate transfer rotator to the recording medium more than when the toner image is transferred from the toner image carrier to the intermediate transfer rotator. An image forming apparatus comprising: a drive control unit that rotationally drives an intermediate transfer rotator so that a toner image is transferred later. 2. When transferring a toner image on a toner image carrier onto an intermediate transfer rotator, the toner image carrier and the intermediate transfer rotator are brought into contact with each other, and a multiple toner image is transferred from the intermediate transfer rotator to a recording medium. The image forming apparatus according to claim 1, further comprising a contacting / separating unit that brings the toner image holding member and the intermediate transfer rotating member into a non-contact state when transferring. 3. A toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface, and is sequentially formed on the toner image carrier during rotation while the outer peripheral surface is in contact with the toner image carrier. , An intermediate transfer rotator on which toner images of different colors are transferred in an overlapping manner so as to form a multiple toner image Toner heating means for melting the multiple toner image of, the recording medium transport means for transporting the multiple toner image on the intermediate transfer rotator to the recording medium, and the detection of the transport of the recording medium Recording medium conveyance detecting means, a warning generating means for issuing a warning when the conveyance of the recording medium is not detected by the recording medium conveyance detecting means, and the recording medium to which the multiple toner images are transferred is pressed against the intermediate transfer rotator. When the recording medium pressing means for causing the recording medium and the conveyance of the recording medium are detected by the recording medium conveyance detecting means, the multi-toner image on the intermediate transfer rotator can be transferred onto the recording medium. The rotation is continued and the recording medium pressing unit is operated to press the recording medium against the intermediate transfer rotating body, and when the recording medium conveyance is not detected by the recording medium conveyance detection unit, the warning unit issues a warning. In order to transfer the multiple toner image on the intermediate transfer rotator to the recording medium when the conveyance of the recording medium is detected after that, the intermediate transfer rotator is stopped to rotate. An image forming apparatus comprising: a control unit that operates the medium pressing unit to press the recording medium against the intermediate transfer rotator and rotate the intermediate transfer rotator. 4. A toner image carrier on which toner images of different colors are sequentially formed on the outer peripheral surface, and a toner image carrier on which the toner images are sequentially formed while the outer peripheral surface rotates while being in contact with the toner image carrier. , An intermediate transfer rotator on which toner images of different colors are transferred so as to form a multiple toner image, and an intermediate transfer rotator on the intermediate transfer rotator so that the multiple toner images on the intermediate transfer rotator can be melt-transferred to a recording medium. A toner heating means for melting the multiple toner image, a recording medium conveying means for conveying the multiple toner image on the intermediate transfer rotator to the recording medium, and a recording medium to which the multiple toner image is transferred. A recording medium pressing unit that presses the intermediate transfer rotating member, a unit that heats the recording medium pressing unit, a temperature detecting unit that detects the temperature of the recording medium pressing unit, and a temperature detecting unit that detects the temperature after the image forming process is started. When the temperature to be output is equal to or higher than a predetermined value, the recording medium pressing unit is operated to press the recording medium against the intermediate transfer rotating body so that the multiple toner images on the intermediate transfer rotating body can be transferred to the recording medium. In addition, the image forming apparatus further comprises a control unit that puts the recording medium pressing unit into a standby state without operating when the temperature detected by the temperature detecting unit is lower than a predetermined value.