JP2001242681A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately carry out processing afterward even when carrying trouble of transfer paper is generated in an image forming device where a multiplex toner image is formed by sequentially transferring toner images of different colors that are sequentially formed on a photoreceptor to an intermediate transfer rotating body, melting them by heating and melt transferring to transfer paper. SOLUTION: In the device, an alarm is emitted when carrying of the transfer paper 26 is not detected by a transfer paper detecting sensor 41, rotation of the intermediate transfer rotating body 2 is stopped and the rotation of the intermediate transfer rotating body 2 is resumed when carrying of the transfer paper 26 is detected by the transfer paper detection sensor 41 afterward.

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 An electrophotographic technique widely used in the related art (that is, an electrostatic latent image is formed on a toner image holding member composed of, for example, a photoreceptor by image exposure, and the resultant is A technology that electrostatically transfers the toner image to a recording medium such as paper by discharge and fixes it)
The problem is that density unevenness occurs in an image, or toner is scattered in a transfer portion, and a background stain on an image occurs. There is also a problem that the resolution and dot reproducibility are poor.

The cause is largely due to the transfer process. That is, due to the unevenness of the surface of the paper, the paper and the photoreceptor do not completely adhere to each other, an uneven gap appears, the transfer electric field is disturbed, and the Coulomb repulsion between the toners is caused. The quality of the product deteriorates.

By the way, toner images of different colors are electrostatically superimposedly transferred to an intermediate transfer rotating body, and a multi-color multiplex toner image is melted on the intermediate transfer rotating body. A technique for transferring a multi-toner image to obtain a color copy has been proposed in, for example, Japanese Patent Application Laid-Open No. 51-94939. According to this method, since the transfer of the toner image to the recording medium is performed non-electrostatically, the above-described deterioration in image quality is less likely to occur. In this type of image forming apparatus, a multi-color multi-toner image formed on an intermediate transfer rotating body is heated by a heater, and the toner is melted before being collectively transferred to a recording medium.

In the image forming apparatus of the type described above, the recording medium is conveyed to its transfer section in order to melt-transfer the multicolored multi-toner image on the intermediate transfer rotating body onto the recording medium. If a conveyance trouble occurs in the medium, the multi-toner image formed on the intermediate transfer rotating body by the process up to that point is wasted. That is, the toner image must be removed from the intermediate transfer rotating body by the cleaning device, and the image forming operation must be performed again.
A great loss occurs both economically and temporally.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to sequentially transfer toner images of different colors formed on a toner image holding member to an intermediate transfer rotating member, and to form a multi-toner formed on the intermediate transferring rotating member. An image forming apparatus of a type in which images are melt-transferred onto a recording medium all at once, and even when a trouble in transporting the recording medium occurs, time and resources are minimized, and subsequent processing is appropriately performed. It is an object of the present invention to provide an image forming apparatus capable of performing the above.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a toner image carrier on which toner images of different colors are sequentially formed on an outer peripheral surface, and an outer peripheral surface contacting the toner image carrier. During the rotation, an intermediate transfer rotator in which toner images of different colors sequentially formed on the toner image holding member are superimposed and transferred so as to form a multiplex toner image, and a multiplex toner image on the intermediate transfer rotator are formed. Toner heating means for fusing the multi-toner image on the intermediate transfer rotator so that the multi-toner image on the intermediate transfer rotator can be transferred to the recording medium; Medium transporting means; recording medium transport detecting means for detecting that the recording medium is being transported; warning generating means for issuing a warning when the transport of the recording medium is not detected by the recording medium transport detecting means; A recording medium pressing unit that presses the recording medium onto which the toner image is to be transferred onto the intermediate transfer rotating body, and a multi-toner image on the intermediate transfer rotating body when the conveyance of the recording medium is detected by the recording medium conveyance detecting unit. The rotation of the intermediate transfer rotator is continued so that the image can be transferred onto the recording medium, and the recording medium pressing means is operated to press the recording medium against the intermediate transfer rotator. If it is not detected by the means, the warning means is activated so that a warning is issued, and the rotation of the intermediate transfer rotating body is stopped, and then, when the conveyance of the recording medium is detected, Control means for operating the recording medium pressing means to press the recording medium against the intermediate transfer rotator, and for rotating the intermediate transfer rotator so as to transfer the multiple toner images on the body to the recording medium; We propose an image forming apparatus equipped.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 schematically shows a main configuration of an image forming apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a drum-shaped photoreceptor, which constitutes an example of a toner image holder on 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 rotator, and reference numeral 3 denotes an endless transport belt. As the photoconductor 1,
For example, an organic photoreceptor having relatively excellent pressure resistance and heat resistance is used.

The photosensitive member 1, the intermediate transfer rotating member 2, and the transport belt 3 are driven to rotate in the directions indicated by arrows, respectively. Of these, the intermediate transfer rotating member 2 has an outer peripheral surface thereof. It rotates while being in contact with the photoreceptor 1, during which it is sequentially formed on the photoreceptor 1 on the surface of the intermediate transfer rotator 2.
Toner images of different colors are overlaid and transferred. Thus, a multiple toner image is formed on the intermediate transfer rotating member 2.

The transport belt 3 constitutes an example of a recording medium transport means for transporting the recording medium in order to transfer the multiplex toner image on the intermediate transfer rotary member 2 to the recording medium.

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

The photoreceptor 1 has a yellow developing unit 7Y, a magenta developing unit 7M, a cyan developing unit 7C, and a black developing unit 7B, which are provided side by side in series in the circumferential direction. Each of these developing devices contains a two-component developer in which a toner and a carrier having different colors of yellow, magenta, cyan, and black are mixed. For example, the yellow developing device 7Y contains a two-component developer obtained by mixing a high-resistance non-magnetic yellow toner and a magnetic carrier. Other developing units also contain a two-component developer mixed with a magnetic carrier, although the color of the toner is different. It is desirable that the toner of each color has a particle size of about 5 μm or less so that the resolution is high, the tone reproducibility by the area tone is good, and the swelling of the toner image due to the superposition is as small as possible. .

For example, the yellow developing unit 7Y has a configuration as shown in FIG. That is, this developing device
It includes a non-magnetic sleeve 9 that has a magnet 8 inside and conveys the developer to the developing area by rotating, and a developer regulating plate 11 that regulates the amount of the developer conveyed on the sleeve. The yellow developer is a stirring member 12,1.
The toner is sufficiently stirred by the toners 3 and 14, during which the yellow toner contacts the carrier (the toner has a negative polarity in this embodiment). 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 have the same configuration. When the selected developing device performs development, a magnetic field is formed on the sleeve so that the developer is supplied, and the sleeve rotates, and at the same time, the sleeve rotates. the 9, the developing bias (approximately -300-1000V) is applied by the bias voltage source _{E 1.}

In the developing area, only the toner is attracted to the electrostatic latent image on the photoconductor and adheres to the photoconductor 1 by the electric field formed between the photoconductor 1 and the photoconductor 1. That is, the toner T adhered to the carrier C on the sleeve 9 adheres to the exposed portion on the photoconductor 1 irradiated with the laser beam. In this way, the electrostatic latent image on the photoreceptor 1 is visualized as a toner image. However, in a developing device that is not selected, the movement of the developer is prevented by the developer regulating plate, and the developing area is not changed. , The developer is not conveyed.

When a bias is applied to the sleeve on which the developer is not conveyed so as to promote the development, the toner of the toner image developed by the other developing device can be prevented from being mixed into the developing device, and the color turbidity can be prevented. Is obtained.

Returning to FIG. 1, it is desirable that the intermediate transfer rotating member 2 has appropriate elasticity so that a sufficient contact area and uniform pressure can be obtained with the photosensitive member 1. In addition, the surface has an adhesive property to the toner at room temperature, and further has a property of easily releasing the melted and fluidized toner to efficiently transfer the toner to the recording medium, that is, heating. In this state, the toner shows releasability from the toner. For example, the surface of the intermediate transfer rotator 2 exhibits adhesiveness to toner at room temperature,
It is made of silicone rubber or the like that shows releasability from the toner when heated.

FIG. 3 shows a specific example of the intermediate transfer rotator 2.
The following can be mentioned. That is, it has a thickness of 500 to 5000 μm and a rubber hardness of 30 to 5000 on a support drum 15 made of a rigid material such as aluminum.
80-degree elastic layer 16, conductive layer 17 of 30 to 300 μm thick made of polyimide in which carbon black is dispersed,
A sheet-like body made of a silicone rubber insulating adhesive layer 18 having a thickness of 10 to 300 μm is bonded with the elastic layer 16 inside. Although this sheet is used as an intermediate transfer medium, the sheet may not be bonded to the support drum 15 but only one end thereof may be fixed on the support drum 15.

The surface of the intermediate transfer rotating member 2 preferably has irregularities smaller than the substantial minimum particle diameter of the toner in order to prevent transfer omission due to the loss of adhesion to the photosensitive member 1. . For example, when the substantially minimum particle size of the toner is 5 μm, it is desirable that the unevenness of the intermediate transfer rotating body 2 be 5 μm or less. The conductive layer 17 is a support drum 15 have been insulated, when the toner image is transferred from the photosensitive member 1 to the intermediate transferring member 2, in its conductive layer 17, a predetermined transfer bias by a bias power source E ₂ is Applied.

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

The intermediate transfer rotator 2 is rotationally driven by driving control means, which will be described later, such that its rotation speed is switched.

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

A heater 25 is provided inside the roller 21 facing the intermediate transfer rotary member 2 among the rollers provided inside the conveyor belt 3, and the heater 25 keeps the temperature of the transfer area at a predetermined value. It is configured to be. The roller 21 presses the transport belt portion wound therearound from the inside thereof to press the belt portion against the intermediate transfer rotary member 2, and transfers the recording medium on the transport belt 3 to the intermediate transfer rotary member 2 as described later. It functions as a pressure roller for pressing. Pressure roller 21 and lower roller 22
Is rotatably mounted on each end of the connecting rod 23, and a solenoid 24 is connected to the connecting rod 23.

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

A spring (not shown) is interposed on each shaft of the intermediate transfer rotating body 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 pressed against the body 2. On the other hand, when the solenoid 24 is excited, the connecting rod 23 is pulled, and the belt portion is separated from the intermediate transfer rotating body 2 as shown by a broken line in FIG. In any case, such a belt portion comes into contact with and separates from the intermediate transfer rotary member 2 according to a predetermined sequence. Solenoid 24
Alternatively, the pressure roller 21 may be moved toward and away from the intermediate transfer rotator 2 by a driving device such as a roller moving motor.

On the other hand, the photosensitive member 1 and the intermediate transfer rotating member 2
Between them, a spring (not shown) is interposed between these shafts, and according to a predetermined sequence, by the operation of a contact / separation motor (not shown), the two are separated from each other or pressed against each other by the action of a cam or the like. It is supposed to.

Here, toner images of different colors are sequentially formed on the photosensitive member 1, and these toner images are superimposedly transferred onto the intermediate transfer rotating member 2, and are transferred onto the intermediate transfer rotating member 2. A multi-toner image is obtained. At this time, the transport belt 3 is separated from the intermediate transfer rotator 2 as shown 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 overlaid and transferred onto the intermediate transfer body 2, the surface of the photoconductor 1 is cleaned by the cleaning device 10.

The transfer paper 26 as an example of a recording medium is sent from the left side of FIG.
Before being transported by the heating roller 27,
(The whole of which is heated to about 50 ° C. to 180 ° C.), thereby being brought into a preheated state. By heating the transfer paper 26 with the conduction heat from the heating roller 27 in contact with the transfer paper 26, the transfer paper 26 can be heated to the target temperature in a short time. The heating roller 27 is formed by coating a hollow rigid roller with a heat-resistant material such as silicone rubber or Teflon (registered trademark) resin, and has a heater (not shown) such as a halogen lamp inside. .

The transfer paper 26 preheated by the heating roller 27 is sent to the conveyor belt 3 and is conveyed by the conveyor belt 3 while the transfer paper 26 is being conveyed by the conveyor belt 3.
With the force of 1, the toner image is pressed onto the intermediate transfer rotating body 2 and the above-described multiple toner image is transferred onto the transfer paper 26. That is, during this transfer, the transport belt 3 is pressed against the intermediate transfer rotating body 2 as shown by a solid line in FIG.
6 is pressed against the intermediate transfer rotator 2 to transfer a multiple toner image thereon.

An example of a recording medium conveyance detecting means for detecting that the recording medium is being conveyed on the upstream side in the conveying direction of the transfer paper 26 from the opposing portion of the pressure roller 21 and the intermediate transfer rotating body 2. 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 releasability of the surface of the intermediate transfer rotator is improved. The toner image on the surface of the intermediate transfer rotating body is transferred to the transfer paper. At this time, another heater 25
Is heated, the toner of the toner image in a molten 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 desirably a state in which the toner is not powder but can be slightly melted and moved, that is, a semi-molten state, and a state in which the viscosity does not become excessively low is preferable.

A transfer belt 3 having a heat generating layer is used, a predetermined voltage is applied to the transfer belt 3 to generate heat, and the transfer paper 26 to be transferred is brought into a preheated state by this heat. good. As described above, when the transfer paper 26 is heated before the transfer, the heat-melting transfer and the fixing can be efficiently performed in combination with the heat imparting action by the heater 25, and the high-speed recording can be supported. .

The portion of the intermediate transfer rotator 2 on which the multiple toner image has been transferred onto the transfer paper 26 is cleaned by the cleaning device 40, and the toner image is again transferred from the photoreceptor 1.
At this time, the surface of the intermediate transfer rotator 2 has already been cooled and returned to normal temperature or a temperature close to this, and the tackiness of the surface has been increased, so that the toner image can be efficiently transferred from the photoconductor 1.

After the transfer of the multiple toner image onto the transfer paper 26, the surface of the intermediate transfer rotating body 2 is blown with cool air by a blower (not shown) and forcedly cooled. To increase its stickiness,
It is desirable that the toner image be easily transferred from the photoconductor 1.

The basic configuration of the image forming apparatus shown in FIGS. 1 to 3 has been described above. An example of an image forming process performed by this image forming apparatus will be described below with reference to the flowchart shown in FIG. However, other configurations will be clarified. In the flowchart, “B
“R” means the intermediate transfer rotating body 2 (the same applies to FIG. 5 described later).

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

(0) First, the temperature control system of the pressure roller 21 is operated. (B1) The pressure roller 21 is driven by the thermistor described above.
Is detected, and when the temperature is equal to or higher than the predetermined temperature, the process proceeds to the previous step. When the pressure roller 21 is lower than the predetermined temperature, the process 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 rotating at high speed in the direction of the arrow in FIG. 1 at the same constant surface linear velocity (for example, 300 mm / s). (3) The charging charger 4 starts discharging, uniformly charging the photoreceptor 1, and setting its surface potential to about -800V. (4) The laser beam 6 modulated based on the image signal by the laser optical system 5 scans the surface of the photoconductor 1 to form an electrostatic latent image on the photoconductor. The electrostatic latent image is formed such that a portion irradiated with the laser beam (surface potential is about -100 V) is used as a toner adhering portion and a non-exposed portion (surface potential is about -800 V) is used as a background portion.

(5) The electrostatic latent image is developed by the yellow developing unit 7Y. In the developing units 7M, 7C and 7B other than yellow, a magnetic field is formed so that the developer is not transported. At this time, the developing bias applied to the sleeve 9 of the yellow developing device 7Y is -600 V, and reversal development is performed. Thus, a yellow toner image is formed on the photoconductor 1. (6) The portion of the photoconductor 1 where the yellow toner image is formed reaches a position where the yellow toner image is pressed against the intermediate transfer rotator 2. The distance between the photosensitive member 1 and the intermediate transfer rotating member 2 is 0.3 to 3.0.
kg / cm pressure is applied to the conductive layer 1 of the intermediate transfer rotating body 2.
7, a transfer bias of +0.5 to 5 kv is applied.

An electric field is formed at the nip portion (contact portion) between the photosensitive member 1 and the intermediate transfer rotating member 2, and the toner is transferred from the photosensitive member 1 to the intermediate portion by the electric field and the adhesiveness of the surface of the intermediate transfer rotating member 2. The image is transferred to the transfer rotating body 2. At this time, in the contact portion between the photosensitive member 1 and the intermediate transfer rotating member 2, the toner is hardly moved because it is sandwiched between them, and the intermediate transfer is performed by the electrostatic force generated by the electric field and the adhesive force from the intermediate transfer rotating member 2. Adhesive force with the rotator 2 increases, and the image is transferred to the intermediate transfer rotator with almost no movement toward the interface.
A cleaning device 10 acts on the rotating photoconductor, and the cleaning device 10 cleans the photoconductor surface after the transfer of the yellow toner. Further, the surface of the photoconductor 1 after the transfer of the toner image is subjected to a charge removing operation by a charge remover (not shown).

(7) (8) (9) Steps (4) to
(6) is executed by selecting the magenta developing device 7M instead of the yellow developing device 7Y. In the transfer of 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 step of transferring the toner image from the photoconductor 1, the magenta toner is almost sandwiched between the photoconductor 1 and the intermediate transfer rotator 2 even on the area of the intermediate transfer rotator 2 where the yellow toner exists. There is no freedom of movement, and the electrostatic pressure due to the electric field increases the adhesive force to the intermediate transfer rotating body 2. When the photosensitive body 1 and the intermediate transfer rotating body 2 separate from each other, the intermediate transfer rotating body separates from the photosensitive body 1. 2 on. (10) to (15) Similarly, (4) to (6) are respectively performed with cyan and black toners, and a multi-color toner image of four colors is formed on the intermediate transfer rotating body 2.

Thus, the toner images of different colors sequentially formed on the outer peripheral surface of the photosensitive member 1 are
The image is superimposed and transferred onto the upper surface so as to form a powdery multiple toner image. Such transfer is performed while the outer peripheral surface of the intermediate transfer rotating body 2 rotates while being in contact with the photoconductor 1.

(16) Discharge from the charger 4 is stopped. (17) The photoconductor 1 moves away from the intermediate transfer rotator 2. (18) The rotation speed of the intermediate transfer rotator 2 becomes lower than before (for example, the surface linear velocity becomes 100 mm / s). (19) At the same time, the transport belt 3 starts rotating at a linear velocity substantially equal to the surface linear velocity of the intermediate transfer rotary member 2 to transport 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 transport belt 3 at a predetermined time, and when the optical reflectance is equal to or more than a predetermined value, it is determined that the transfer paper 26 has been transported, and the process proceeds to step (22) and thereafter. If the reflectance is smaller than the predetermined value, it is determined that the transfer paper is not being conveyed, (20) a warning is displayed on the display unit, and (21) each drive unit stops. When the transfer of the transfer paper is not detected by the transfer paper detection sensor 41, a warning is issued, the fact is notified to the operator, and the rotation of each element including the intermediate transfer rotator 2 is stopped. In this example, the display unit constitutes an example of a warning generation unit that issues a warning when the conveyance of the recording medium is not detected by the recording medium conveyance detection unit.

(B3) If the operator processes the cause of the transfer paper not being conveyed and restarts, the process is executed again from step (18). After the rotation of the intermediate transfer rotator 2 is stopped based on the fact that the transfer paper is not conveyed, when the transfer paper detection sensor 41 detects the conveyance of the transfer paper 26, the rotation of the intermediate transfer rotator 2 is stopped. It will resume.

(22) The timing at which the multicolor multiplex toner image of the intermediate transfer rotator 2 moves with the rotation of the intermediate transfer rotator 2 and the leading end of the image is transferred to the leading end of the transfer paper 26 Then, the transfer paper is transported by the transport belt 3. The intermediate transfer rotator 2 and the conveyor belt 3 are pressed against each other by a pressure roller at a pressure of 0.3 to 3.0 kg / cm. The operation of the solenoid 24 or other driving device raises the pressure roller 21 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 image is transferred to the intermediate transfer rotating body.

When the multi-toner image on the intermediate transfer rotating member 2 is in contact with the transfer paper 26, the toner of the multi-toner image is The heater 19 is turned on at such a timing as not to prevent the transfer of the powdery toner of each color sequentially from 1 and the formation of the powdery multiple toner image on the intermediate transfer rotating body 2. In addition, at this time, since the pressure roller 21 is heated by the internal heater 25, the intermediate transfer rotator 2
The upper multiple toner image is heated from the inside of the intermediate transfer rotating body 2 and from the side of the pressure roller 21 via the transfer paper 26, easily melts, flows on the transfer paper 26, and flows into the paper fibers. Penetrate into

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

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

(23) The pressure roller 21 separates from the intermediate transfer rotating body 2. (24) The surface of the intermediate transfer rotator 2 is cleaned by the cleaning device 40, the temperature is reduced by natural cooling or forced cooling, and the intermediate transfer rotator 2 exhibits adhesiveness again, preparing for the next transfer of the toner image. (B4) When a recording image is subsequently formed, the process is executed again from the process (1). (25) When an image is not formed, each driving portion stops and a series of image processes ends.

In the above-described image forming apparatus, the photosensitive member 1
To transfer the toner image to the intermediate transfer rotator 2, and repeat this process to form a multiple toner image on the intermediate transfer rotator 2. This multiple toner image is 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 is higher when the multi-toner image is melt-transferred from the intermediate transfer rotator 2 to the transfer paper 26 than when the toner image is transferred from the photoconductor 1 to the intermediate transfer rotator 2. The rotation of the intermediate transfer rotator 2 is controlled so that the speed of the fusion transfer of the multiplex toner image from the intermediate transfer rotator 2 to the transfer paper 26 is slower than the other process speeds. The time required for the toner image to pass through the contact portion between the intermediate transfer rotator 2 and the transfer paper 26 can be lengthened.

For this reason, the heat of the toner melted on the intermediate transfer rotating member 2 is taken by the transfer paper 26 when the multi-toner image is melt-transferred onto the transfer paper 26, and the toner is transferred onto the transfer paper 26. Can prevent the problem of being hardened immediately. That is, the multi-toner image can be melt-transferred onto the transfer paper 26 without any trouble without causing the intermediate transfer rotating body 2 and the pressure roller 21 to have a very high temperature by the heaters 19 and 25.
The amount of heat energy consumed can be reduced.

After the intermediate transfer rotator has left the transfer portion during the fusion transfer of the multiple toner image, a longer cooling time can be taken. As a result, it is possible to prevent the intermediate transfer rotator 2 having a high temperature from coming into contact with the photoreceptor 1, thereby preventing a problem that the photoreceptor 1 is adversely affected by heat.

Further, when a toner image is transferred from the photoreceptor 1 to the intermediate transfer rotating body 2, the surface linear velocity of the intermediate transfer rotating body 2 can be increased, so that a problem that the recording speed becomes slow can be prevented.

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

In this way, the multi-toner image can be melt-transferred onto the transfer paper 26 efficiently with little heat energy without lowering the recording speed, and can be fixed.

The photosensitive member 1 and the intermediate transfer rotating member 2 may be kept in contact with each other, but in this embodiment, when the toner image on the photosensitive member 1 is transferred onto the intermediate transfer rotating member 2, 1 contacts the intermediate transfer rotator 2, but when the multi-toner image is collectively transferred from the intermediate transfer rotator 2 to the transfer paper,
The photoreceptor 1 is separated from the intermediate transfer rotator 2 to be in a non-contact state. That is, the photoconductor 1 and the intermediate transfer rotator 2 are pressed against each other only when a multi-toner image of the powdery toner is formed on the intermediate transfer rotator 2, and otherwise the two are separated. According to such a configuration, it is possible to prevent a problem that an unnecessary load is applied to the photoconductor 1 and the intermediate transfer rotating body 2, and it is also possible to eliminate a problem that the photoconductor 1 is deteriorated by the action of heat. When the photoreceptor 1 performs the contacting / separating operation with respect to the intermediate transfer rotating body 2, the charging charger 4, the developing units 7Y, 7M, 7C, 7B, the cleaning device 10 and the like around the photoreceptor 1 also operate together with the photoreceptor 1. It is desirable to assemble them integrally.

After the multicolor toner image is formed on the intermediate transfer rotating member 2, if the transfer paper 26 is not conveyed, a warning is issued and the operation is interrupted. When the sheet is conveyed, the operation is restarted from the process of transferring the multi-toner image from the intermediate transfer rotating body 2 to the transfer paper 26. That is, when the transfer of the transfer paper 26 is detected by the transfer paper detection sensor 41, the rotation of the intermediate transfer rotator 2 is performed so that the multiplex toner image on the intermediate transfer rotator 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 rotating body 2. Conversely, when the transfer of the transfer paper 26 is not detected by the transfer paper detection sensor 41, the display unit is activated so as to issue a warning, and the rotation of the intermediate transfer rotator 2 is stopped. Is detected, the pressure roller 21 is operated to press the transfer paper 26 against the intermediate transfer rotator 2 so as to transfer the multiple toner image on the intermediate transfer rotator 2 to the transfer paper 26,
In addition, the intermediate transfer rotator 2 is rotated. With such a configuration, the process (time, energy consumption, consumables, etc.) up to the formation of the multiple toner image is not wasted, and no load is imposed on the cleaning of the intermediate transfer rotating member 2.
Images can be output immediately after properly treating the device.

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 is present, the transfer electric field is weakened by the effect of the charge of the yellow toner, and the magenta toner Are more susceptible to Coulomb repulsion, and the yellow toner serves as a spacer, so that the adhesion between the photoreceptor 1 and the intermediate transfer rotator 2 is weakened.

Therefore, it is preferable that the conditions (transfer bias, transfer pressure) of the primary transfer step (6) are switched and set for each color of toner. As an example, +200 V (condition 1) for yellow toner transfer, +500 V (condition 2) for magenta toner transfer, +800 V (condition 3) for cyan toner transfer, and +200 V for black toner transfer.
1200 V (condition 4) is applied. This way,
The electrical effect of the toner already transferred onto the intermediate transfer rotating body 2 can be reduced, and the transfer pressure can be gradually increased to improve the adhesion between the photoconductor 1 and the intermediate transfer rotating body 2.

The photosensitive member 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. In particular, to prevent toner from being directly transferred to the surface of the transport belt 3,
When the belt 3 does not hold the transfer paper 26, the pressure roller 21 is lowered, and control is performed so that the intermediate transfer rotating body 2 and the transport belt 3 do not come into contact with each other. Further, the heating roller 27 is
The heating roller and the conveyor belt 3 may be provided to face the conveyor belt 3 in this case.
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 of the pressure roller 21 is detected by a temperature detecting means composed of a thermistor, and the on / off of the heater 25 is controlled based on the result. When the temperature of the pressure roller 21 becomes higher than a predetermined temperature at the start of the operation, an actual image forming process is started. When the temperature of the pressure roller 21 is lower than the predetermined temperature, the apparatus is kept in a standby state. However, according to this configuration, a warm-up time is required until the temperature of the pressure roller 21 rises to the same degree before the start of the image forming process.

Therefore, no matter what the temperature of the pressure roller 21 is, the image forming process is first started, and after the start of the process, the temperature of the pressure roller 21 is detected. When the temperature is lower than a predetermined value, the apparatus is set in a standby state when the temperature is lower than a predetermined value. By utilizing the time until the operation is started to press the paper 26, the temperature of the pressure roller 21 can be increased, and the waiting time of the operator can be reduced or eliminated.

A specific example in which such an operation is performed by the image forming apparatus shown in FIGS. 1 to 3 will be described with reference to a 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 described in a simplified manner. In FIG. 5, the operation related to switching of the rotation speed of the intermediate transfer rotator 2 is omitted.

(0) The temperature control system of the pressure roller 21 is operated. (1) The photosensitive member and the intermediate transfer rotating member are pressed against each other. (2) The photoreceptor and the intermediate transfer rotator are each started to rotate at the same constant linear velocity in the direction of the arrow in FIG. (3) Turn on the charger 4 to start discharging,
The photoconductor 1 is uniformly charged. (4) The surface of the photoreceptor is scanned by the laser light 6 modulated based on the image signal by the laser optical system 5, and an electrostatic latent image is formed on the surface. (5) The electrostatic latent image is developed by the yellow developing device 7Y. In the developing units 7M, 7C and 7B other than yellow, a magnetic field is formed so that the developer is not transported. (6) A transfer bias voltage is applied to the conductive layer 17 of the intermediate transfer rotator. A cleaning device 10 acts on the rotating photoconductor, and the cleaning device 10 cleans the photoconductor surface after the transfer of the yellow toner image.

(7) (8) (9) Steps (4) to
(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 to 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 over the yellow toner image. (10) to (15) Similarly, processes similar to (4) to (6) are respectively performed for cyan and black toners, and a multi-color toner image of four colors is formed on the intermediate transfer rotating body 2.

(16) The charger 4 is turned off, and the discharge stops. (17) The photoconductor 1 moves away from the intermediate transfer rotator 2. (B1) An output from a temperature sensor for detecting the temperature of the pressure roller 21, in this example, a thermistor is determined. If the output is equal to or more than 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 set in a standby state. (19) In order to transport the transfer paper 26 in parallel, the transport belt 3 is driven to rotate at a linear speed substantially equal to that of the intermediate transfer rotating body 2.

(B2) The transfer paper is the transfer paper detection sensor 4
In step 1, if it is determined that the transfer sheet has been conveyed, the process proceeds to step (22) and subsequent steps.
If it is determined that the transfer paper is not being conveyed, (20) a warning is displayed on the display unit, and (21) each drive unit is stopped. (B3) When the operator processes the cause of the transfer paper not being conveyed and restarts the process, the process is executed again from the determination (B1). (22) The intermediate transfer rotating body 2 and the transport belt 3 are pressed against each other by the pressing roller 21 with the transported transfer paper 26 interposed therebetween. As a result, the multiple toner image on the intermediate transfer rotating body 2 is secondarily transferred and fixed to the transfer paper 26.

(23) The pressure roller 21 separates from the intermediate transfer rotating body 2. (24) The surface of the intermediate transfer rotating body 2 is cleaned by the cleaning device 40. (B4) When a recording image is subsequently formed, the process is executed again from the process (1). (25) When an image is not to be continuously formed, each driving portion is stopped, and this series of image forming processes is terminated.

As described above, after the start of 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 rotating body 2 is transferred to the transfer paper 2.
6 so that the transfer paper is pressed against the intermediate transfer rotator 2 so that the transfer paper can be transferred to the transfer roller 6. If the temperature detected by the temperature detecting means is lower than a predetermined value, the pressure roller 21 is Since the standby state is set without operation, 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 only possible by using the intermediate transfer rotating body.

The above process can be performed by a control system as schematically shown 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 a control program, and includes a charging charger, a laser optical system, each developing unit, a main motor (which drives an intermediate transfer rotating body and can switch between two speeds), a transport motor, a solenoid, each contact / separation motor, and a display. Section, a cleaning device, a heater in the pressure roller, and the like.

The photosensitive member, the intermediate transfer rotating member, and the transport belt are driven to rotate by independent driving sources or by a common driving source. 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, the motor 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 example, the control unit and the main motor shown in FIG. 6 cause the surface linear velocity of the intermediate transfer rotator to transfer the toner image from the toner image holder to the intermediate transfer rotator. The drive control means for rotating and driving the intermediate transfer rotator is configured such that the transfer of the multi-toner image from the intermediate transfer rotator to the recording medium is slower than the transfer of the multi-toner image.

In this embodiment, when the toner image on the toner image carrier is transferred onto the intermediate transfer rotating member by the control unit and the photosensitive member contacting / separating motor shown in FIG. When the multi-toner image is transferred from the intermediate transfer rotator to the recording medium by bringing the intermediate transfer rotator into contact with the body, a contacting / separating unit that configures the toner image holder and the intermediate transfer rotator in a non-contact state is configured.

Similarly, in this embodiment, the conveyance of the recording medium is detected by the recording medium conveyance detecting means by the control unit, the main motor, and the pressure roller contacting / separating solenoid (or a driving device such as a motor) shown in FIG. In such a case, the multi-toner image on the intermediate transfer rotator can be transferred onto a recording medium.
The rotation of the intermediate transfer rotator is continued, and the recording medium is pressed against the intermediate transfer rotator by operating the recording medium pressing means. When the conveyance of the recording medium is not detected by the recording medium conveyance detection means, the warning means is provided. Activate this so that a warning is issued, and stop the rotation of the intermediate transfer rotator. Then, when the conveyance of the recording medium is detected, the multi-toner image on the intermediate transfer rotator is transferred to the recording medium. In order to perform this operation, control means for operating the recording medium pressing means to press the recording medium against the intermediate transfer rotating body and rotating the intermediate transfer rotating body is configured.

Similarly, in this embodiment, in the present embodiment, the control unit and the pressure roller contacting / separating solenoid (or a driving device such as a motor) shown in FIG. If the detected temperature is equal to or higher than the predetermined value, 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 to the recording medium. In addition, when the temperature detected by the temperature detecting unit is lower than a predetermined value, a control unit is configured to be in a standby state without operating the recording medium pressing unit.

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

Instead of the drum-shaped toner image carrier and the intermediate transfer rotating body, a belt-shaped one may be used, or the recording medium conveying means may be constituted by a drum or a conveying roller.

[0080]

According to the image forming apparatus of the first aspect, when the recording medium is not conveyed, the operation is interrupted, and when the recording medium is conveyed properly, the recording medium is transferred from the intermediate transfer rotating body to the recording medium. Since the operation can be resumed from the process of transferring the multi-toner image, the process (time, energy consumption, consumables, etc.) up to the formation of the multi-toner image is not wasted, and a burden is placed on the cleaning of the intermediate transfer rotating body. The image can be output immediately after the device is properly treated, without the need for any treatment.

[Brief description of the 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 illustrating one of developing units provided in the image forming apparatus.

FIG. 3 is an enlarged view showing a part of the intermediate transfer rotating body in section.

FIG. 4 is a diagram showing a flowchart corresponding to the 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]

 2 Intermediate transfer rotator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/24 G03G 15/24 21/14 21/00 386 21/00 386 372

Claims (1)

[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 is sequentially formed 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 superimposed and transferred to form a multi-toner image; and an intermediate transfer rotator on the intermediate transfer rotator so that the multiplex toner image on the intermediate transfer rotator can be melt-transferred onto a recording medium. A toner heating unit for melting the multi-toner image, a recording medium conveying unit for conveying the multi-toner image on the intermediate transfer rotating body to the recording medium, and detecting that the recording medium is being conveyed. Recording medium conveyance detection means, a warning generation means for issuing a warning when the conveyance of the recording medium is not detected by the recording medium conveyance detection means, and pressing the recording medium on which the multiple toner image is transferred to the intermediate transfer rotating body. A recording medium pressing means for causing the intermediate transfer rotator to transfer the multiplex toner image on the intermediate transfer rotator onto the recording medium when the conveyance of the recording medium is detected by the recording medium conveyance detecting means. While the rotation is continued, and the recording medium pressing means is operated to press the recording medium against the intermediate transfer rotating body, and when the conveyance of the recording medium is not detected by the recording medium conveyance detecting means, the warning means issues a warning. As described above, this is operated, and the rotation of the intermediate transfer rotator is stopped. Then, when the conveyance of the recording medium is detected, the recording is performed so that the multiple toner image on the intermediate transfer rotator is transferred to the recording medium. An image forming apparatus comprising: control means for operating the medium pressing means to press the recording medium against the intermediate transfer rotating body and rotating the intermediate transfer rotating body.