JPH11119592A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where the deterioration of image quality caused by the speed fluctuation of a toner image carrier is prevented. SOLUTION: This device is provided with a rotational speed fluctuation suppressing device 60 constituted of a generator 61 connected to the driving shaft 22 of an intermediate transfer body 21 and a variable resistor 62 consuming electric power generated by the generator 61, and when the rotation of a motor 51 is transmitted to a driving shaft 22 and the intermediate transfer body 21 is rotated, the generator 61 connected to the driving shaft 22 is simultaneously rotated, so that the electric power generated by the generator 61 is consumed by the variable resistor 62. Thus, a stationary rotational load is imparted to the intermediate transfer body 21 and the fluctuation of the rotational speed of the intermediate transfer body 21 is suppressed, and the speed fluctuation of an electrostatic latent image carrier is consequently suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used for an electrostatic recording type printer or copier.

[0002]

2. Description of the Related Art Conventionally, in an electrostatic recording type image forming apparatus, an electrostatic latent image is formed on an electrostatic latent image carrier using a light beam, a laser beam, an ion beam, or the like according to image information. 2. Description of the Related Art A method has been widely adopted in which a latent image is developed by a developing unit to form a toner image on an electrostatic latent image carrier, and the toner image is transferred to a recording medium and fixed to obtain a recorded image. As a method for transferring the toner image on the electrostatic latent image carrier to the recording medium, a direct transfer method for directly transferring the toner image on the electrostatic latent image carrier to the recording medium, and a method for transferring the toner image on the electrostatic latent image carrier There is an intermediate transfer system in which an image is temporarily transferred once to an intermediate transfer member, and then a toner image on the intermediate transfer member is secondarily transferred to a recording medium. Each of these two systems has advantages and disadvantages, but in general, an intermediate transfer system is often used in a color image forming apparatus. Also, a so-called transfix method in which a transfer unit for transferring a toner image to a recording medium and a fixing unit for fixing the transferred toner image are provided as independent units, and a so-called transfix method in which a single unit performs fixing simultaneously with transfer. There is.

In the case of the direct transfer method, in order to transfer a toner image formed on an electrostatic latent image carrier to a recording medium, a toner image is formed between the electrostatic latent image carrier and a transfer roll or a transfer fixing roll. The toner image on the electrostatic latent image carrier is transferred to the recording medium or fixed simultaneously with the transfer by passing the recording medium through the nip portion, and the electrostatic latent image carrier and the transfer roll or the transfer fixing roll When the leading edge of the recording medium enters the nip portion and when the trailing edge of the recording medium leaves the nip portion, the load torque of the electrostatic latent image carrier temporarily fluctuates due to the impact of the entry or detachment, resulting in static. A phenomenon that the rotation speed of the latent image carrier fluctuates may occur. When the distance between the transfer unit and the fixing unit is shorter than the length of the recording medium, when the leading end of the recording medium enters the fixing unit, the impact is applied to the electrostatic latent image carrier via the recording medium. The phenomenon that the transmitted torque is temporarily fluctuated and the rotational speed of the electrostatic latent image carrier fluctuates may occur. In addition, each time a cleaning blade or a cleaning roller for removing toner on the electrostatic latent image carrier slides or separates from the surface of the electrostatic latent image carrier, the load torque of the electrostatic latent image carrier is temporarily reduced. In some cases, the rotational speed of the electrostatic latent image carrier may fluctuate.

On the other hand, in the case of the intermediate transfer system, when the leading end of the recording medium enters the nip between the intermediate transfer body and the transfer roll, and when the end of the recording medium leaves the nip,
The impact of the entry or the detachment causes a temporary rotation speed fluctuation in the intermediate transfer body, and the rotation speed fluctuation of the intermediate transfer body is transmitted to the electrostatic latent image carrier. When the rotational speed of the electrostatic latent image carrier fluctuates during the formation of the electrostatic latent image on the electrostatic latent image carrier, the electrostatic latent image formed on the electrostatic latent image carrier is disturbed. Occurs. Density unevenness occurs in a toner image obtained by developing the disturbed electrostatic latent image. Also, a so-called tandem type color, in which a plurality of electrostatic latent image carriers are arranged along the intermediate transfer member, and toner images of each color formed on each of the electrostatic latent image carriers are sequentially transferred to the intermediate transfer member. In the image forming apparatus, the speed of each electrostatic latent image carrier changes at the time of forming the electrostatic latent image, and as a result, a color shift occurs in the toner images obtained by superimposing the toner images of the respective colors. In addition, when the leading edge of the recording paper enters the fixing unit while the toner image on the intermediate transfer body is being transferred to the recording paper, the speed of the intermediate transfer body also fluctuates. There is a possibility that smear may occur in the toner image.

In view of the above, various methods have been proposed for suppressing the fluctuation in the speed of the electrostatic latent image carrier or the intermediate transfer member, which causes the density unevenness, color shift and smear.
For example, Japanese Patent Application Laid-Open No. Hei 4-221974 discloses a color image in which a flywheel having a large moment of inertia is provided at one end of a driving roller for driving a belt-shaped intermediate transfer body so as to suppress the speed fluctuation of the intermediate transfer body. A forming apparatus is disclosed. In Japanese Patent Application Laid-Open No. 7-239589, a sliding member having a large moment of inertia is rotatably mounted on a drive shaft for driving the electrostatic latent image carrier inside the drum of the electrostatic latent image carrier of the color image forming apparatus. , The sliding member is brought into sliding contact with the inner peripheral surface of the drum to apply a steady load torque relatively larger than the speed fluctuation of the electrostatic latent image carrier to the electrostatic latent image carrier, A method is disclosed in which the speed variation of the latent image carrier is set to a value relatively smaller than the load torque to suppress the speed variation of the electrostatic latent image carrier caused by the load variation.

[0006]

However, in the color image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 4-221974, it is necessary to provide a flywheel having a large moment of inertia at one end of a driving roller for driving the intermediate transfer member. Therefore, problems such as an increase in the size of the image forming apparatus and an increase in power consumption occur. Further, in the color image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 7-239589, a sliding member is slidably contacted with the inner peripheral surface of the drum of the electrostatic latent image carrier. In addition to the difficulty in maintaining the force, the application of such a configuration to a tandem color image forming apparatus having a plurality of electrostatic latent image carriers complicates the configuration of the image forming apparatus. In addition, since the same frictional force is not applied to the four electrostatic latent image carriers in the sliding contact by the sliding members, the expected effect is hardly obtained.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which the occurrence of image quality defects due to speed fluctuations of an electrostatic latent image carrier is prevented.

[0008]

An image forming apparatus according to the present invention for achieving the above object has a toner image carrier which carries a toner image and rotates in a predetermined direction, and the toner image on the toner image carrier. In an image forming apparatus for transferring an image onto a predetermined recording medium and fixing the same to form an image on the recording medium, a rotational force that suppresses fluctuations in the rotational speed of the toner image carrier by applying a braking force to the toner image carrier Speed fluctuation suppressing means, wherein the rotational speed fluctuation suppressing means includes a generator connected to a drive shaft of the toner image carrier, and a load consuming power generated by the generator. Features.

Here, the toner image carrier is provided with an electrostatic latent image formed by developing an electrostatic latent image with toner in the so-called direct transfer system described above. It may mean an image carrier,
In the above-described so-called intermediate transfer method, an intermediate transfer body that receives primary transfer of a toner image from an electrostatic latent image carrier may be used, and the concept includes both of them.

[0010] The term "coupled to the drive shaft" means both a case where the generator is directly connected to the drive shaft and a case where the generator is connected via transmission means such as a gear or a belt. doing.

[0011]

Embodiments of the present invention will be described below. FIG. 1 is an overall configuration diagram of a color printer to which the image forming apparatus of the present invention is applied. As shown in FIG. 1, the color printer 100 has an electrostatic latent image carrier on which electrostatic latent images of yellow (Y), magenta (M), cyan (C), and black (K) are formed. Body 3
a, 3b, 3c, and 3d indicate primary transfer positions T11, T12, and T on the circumference of the intermediate transfer body 21 rotating in the direction of arrow A.
13 and T14, they are arranged in contact with the intermediate transfer member 21.

Each of the electrostatic latent image carriers 3a, 3b, 3c, 3d
The chargers 2a, 2b, 2c, 2d uniformly charge the surfaces of the respective electrostatic latent image carriers, and form an electrostatic latent image on the uniformly charged surfaces of the electrostatic latent image carriers. An electrostatic latent image forming apparatus 1a, 1b, 1c, 1d, a developing device for developing an electrostatic latent image formed on the surface of each electrostatic latent image carrier with the toner of each color to form a toner image of each color. 4a, 4b, 4c, 4
d, cleaners 5a and 5 for cleaning the surface of each electrostatic latent image carrier
b, 5c and 5d are provided respectively.

The intermediate transfer member 21 includes an electrostatic latent image carrier 3a,
This is for receiving the primary transfer of the toner image of each color formed on 3b, 3c, 3d and secondary transferring it to the transfer medium P. The primary transfer position T14 on the circumference of the intermediate transfer body 21
A transfer roll 25 that rotates in the direction of arrow B in contact with the intermediate transfer body 21 with the transfer medium P interposed therebetween is provided at the secondary transfer position T2 on the downstream side of the transfer medium P.

The secondary transfer position T of the intermediate transfer member 21
A cleaner 6 for cleaning the surface of the intermediate transfer body 21 is provided downstream of the rotation direction 2 in the rotation direction A. Further, the color printer 100 includes a fixing device 31 for fixing the toner image transferred to the transfer medium P. The electrostatic latent image forming apparatuses 1a, 1b, 1c, and 1d have electrostatic latent image carriers 3a, 3b, 3c used in the image forming apparatus.
When the photoconductor 3d is a photoconductor, an optical writing type electrostatic latent image forming apparatus such as a laser or an LED is used, and the electrostatic latent image carriers 3a, 3b, 3c and 3d use a dielectric. In such a case, an electrostatic latent image forming apparatus of an ion writing system such as a multi-stellice head or an ion flow control head is used. In the present embodiment, a laser beam writing device is used as the electrostatic latent image forming device because a photosensitive drum is used as the electrostatic latent image carrier.

The chargers 2a, 2b, 2c and 2d uniformly charge the surfaces of the electrostatic latent image carriers 3a, 3b, 3c and 3d at a predetermined potential, and are represented by corotrons and scorotrons. Non-contact charging devices, brushes, rolls,
A contact-type charging device such as a film can be used. In the present embodiment, BCR (Bias ChargeR) is used.
all).

Electrostatic latent image carriers 3a, 3b, 3c, 3d
As the material, a conductive pipe formed by coating a dielectric layer or a photosensitive layer around a conductive pipe can be used. As the material of the conductive pipe, a metal, for example, stainless steel, aluminum, or the like, a metal on which aluminum, copper, or the like is deposited or plated, or a conductive powder such as metal or carbon, or a plastic mixed with filler For example, phenol, nylon, polyacetal, polycarbonate, ABS, polyethylene, polystyrene, polyphenylene ether, polybutylene terephthalate, P
A simple substance such as ET (polyethylene terephthalate) or an alloy type can be used. As the dielectric layer, a dielectric such as acrylic-modified polyurethane, polycarbonate, or PET can be used. As the photosensitive layer, an inorganic photosensitive member such as Se, Cds, or α-Si, or an organic photosensitive member having a multilayer structure is used. Etc. can be used.

In this embodiment, as the electrostatic latent image carrier,
A multi-layered organic photoreceptor comprising a charge injection blocking layer, a charge generation layer, and an electric field transport layer is coated around a stainless steel pipe having a diameter of 30 mm. As the charge injection blocking layer, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl methyl ether, polyamide, thermoplastic polyester, phenoxy resin, casein, gelatin, thermoplastic resins such as nitrocellulose,
Thermosetting resins such as polyimide, polyethyleneimine, epoxy resin, melamine resin, phenolic resin, polyurethane resin, etc., and organometallic compounds such as titanium coupling agent, zirconium coupling agent, silane coupling agent, etc., alone or in combination of two or more Can be used. As the charge generation layer, azo dyes such as chlorodiane blue, anthantrone, quinone pigments such as pyrenequinone, quinocyanine pigments, perylene pigments,
Indigo pigments, bisbenzimidazole pigments, metal-free phthalocyanines, copper phthalocyanines, vanadyl phthalocyanines, titanyl phthalocyanines, phthalocyanine pigments such as gallium phthalocyanine, azurenium salts, squarylium pigments, those selected from charge generation materials such as quinacridone pigments may be used. it can. As the electric field transport layer, an anthracene, pyrene, a polycyclic aromatic compound such as phenanthrene, or a compound having a nitrogen-containing heterocyclic ring such as indole, carbazole, imidazole,
Materials selected from charge transport materials such as pyrazoline compounds, hydrazone compounds, triphenylmethane compounds, triarylamine compounds, enamine compounds, and stilbene compounds can be used.

The developing devices 4a, 4b, 4c and 4d include:
For example, any of a developing device using a liquid and a developing device using a powder can be used. Among the developing devices using powder, either a developing device using a two-component developer containing a toner and a magnetic carrier or a developing device using a one-component developer containing only a toner can be adopted.
Further, as the toner, either a magnetic toner or a non-magnetic toner can be used. In the present embodiment, a two-component developer containing a powder toner and a magnetic carrier is used.

As the cleaners 5a, 5b, 5c, 5d, for example, a cleaner of a blade type, a brush type, a web type, a mag roll type, an electrostatic attraction roll type, or the like can be used. In this embodiment, a blade-type cleaner is used. In addition, the cleaners 5a, 5
Those similar to those used for b, 5c and 5d can be used.

The intermediate transfer member 21 has the form of an intermediate transfer member.
When the type is a drum type, the electrostatic latent image carriers 3a, 3
semi-conductive around conductive pipe similar to b, 3c, 3d
Can be used. Middle
If the type of transfer body is a belt type,
Dispersion of conductive powder in the volume resistance 10⁶ Ω · cm-10
¹⁴Ω · cm can be used. Thin film filter
Lum is polyethylene terephthalate, polycarbonate
Bonate, polyimide, etc. can be used.
Conductive powder to be dispersed in carbon powder, metal powder, etc.
Can be used. Also, as the structure of the intermediate transfer body
Has a thickness of 0.5 μm to 2
Multi-layer structure covered with a thin dielectric layer of about μm
Can also be used. In this embodiment, a drum type intermediate
A transcript is used.

In the present embodiment, the fixing device 31 is a fixing device including a pair of a heating roll 31a and a pressing roll 31b. In addition, a fixing device including a heating roll and a pressing belt, A fixing device including a heating belt and a pressure roll can be used. As the heating roll, for example, a thickness of 0.
A so-called soft roll coated with silicon rubber or viton rubber of about 2 mm to 7 mm, or a so-called hard roll coated with a fluorine-based resin instead of these rubbers can also be used. As the pressure roll, a roll obtained by coating the outer peripheral surface of a metal cylinder with rubber or a fluorine-based resin can be used.

The color printer 1 configured as described above
A color print can be formed on the transfer medium P by forming an image by a well-known electrophotographic process using the image forming apparatus 00. However, if the rotation speed of the intermediate transfer body 21 in the color printer 100 fluctuates, , Image quality defects such as density unevenness, color misregistration, and smear may occur in a color print. Therefore, the first embodiment of the present invention is provided with the following rotational speed fluctuation suppressing device.

FIG. 2 is a schematic configuration diagram of a rotation speed fluctuation suppressing device provided in the first embodiment of the present invention. FIG. 2 shows a drum-shaped intermediate transfer body 21, a motor 51 that drives the drive shaft 22 of the intermediate transfer body 21 via a gear group 56,
A rotation speed fluctuation suppression device 60 including a generator 61 connected to the drive shaft 22 of the intermediate transfer body 21 and a variable resistor 62 consuming power generated by the generator 61 is shown.

When the rotation of the motor 51 is transmitted to the drive shaft 22 via the gear group 56 and the intermediate transfer body 21 rotates, the generator 61 connected to the drive shaft 22 also rotates at the same time. Since the power generated by the generator 61 is consumed by the variable resistor 62, a constant braking force acts on the intermediate transfer body 21. In this way, a constant rotational load is applied to the intermediate transfer body 21, and the fluctuation of the rotation speed of the intermediate transfer body 21 is suppressed.
As the generator 61, either an AC or DC generator can be used.

In the rotational speed fluctuation suppressing device 60, the amount of the rotational load applied to the intermediate transfer body 21 by the rotational speed fluctuation suppressing device 60 can be freely set by adjusting the resistance value of the variable resistor 62. Can be. FIG. 3 shows FIG.
FIG. 4 is a graph showing the speed fluctuation of the intermediate transfer body when the rotation speed fluctuation suppressing device shown in FIG.
3 is a graph showing a speed fluctuation of the intermediate transfer member when the rotation speed fluctuation suppressing device shown in FIG. 2 is operated.

When the rotation speed fluctuation suppressing device (see FIG. 2) is not operated, as shown in FIG.
Seconds), ie, the secondary transfer position T2 (see FIG. 1).
When the transfer medium P enters the transfer nip between the intermediate transfer body 21 and the transfer roll 25, the rotation speed of the intermediate transfer body greatly fluctuates. However, when the rotation speed fluctuation suppressing device is operated, the rotation speed of the intermediate transfer member is not changed even if the transfer medium P enters the transfer nip at the time point A (at the time point of 2.8 seconds) as shown in FIG. No special changes are shown. Further, regardless of whether the transfer medium enters the transfer nip or not, the speed fluctuation rate of the intermediate transfer body is lower in FIG. 4 as a whole than in FIG. As described above, not only the speed fluctuation due to the impact of the transfer medium entering and leaving the transfer nip, but also the speed fluctuation due to the rattling of the meshing of the gear system, the rotational force fluctuation suppressing device applies the braking force applied to the intermediate transfer body. By the action, the speed fluctuation of the intermediate transfer body is suppressed, and thus the speed fluctuation of the electrostatic latent image carrier is suppressed.

Next, a second embodiment of the present invention will be described. FIG. 5 is a schematic configuration diagram of the second embodiment of the present invention. FIG. 5 shows a drum-shaped intermediate transfer body 21, a motor 51 for driving the drive shaft 22 of the intermediate transfer body 21 via a group of gears 56, and a generator 71 connected to the drive shaft 22 of the intermediate transfer body 21. Further, a charging device 73 for storing the electric power generated by the generator 71 and a rotation speed fluctuation suppressing device 70 including a constant current holding device 72 for keeping the current generated by the generator 71 constant are shown.

With this configuration, the motor 5
When the rotation of 1 is transmitted to the drive shaft 22 via the gear group 56 and the intermediate transfer body 21 rotates, the generator 71 connected to the drive shaft 22 also rotates at the same time. The electric power generated by the generator 71 is charged to the charging device 73 through the constant current holding device 72. The electric power stored in the charging device 73 is supplied to necessary portions in the image forming apparatus and is effectively used.

As the charging device 73, a charging device such as a capacitor or a storage battery can be used. Since the charging current to such a charging device gradually decreases as the charging potential rises, the rotational load on the intermediate transfer body 21 generated by the generator 71 also decreases accordingly. Therefore, the rotation speed fluctuation suppressing device 70 of the present embodiment is configured to generate a power by the generator 71 by bypassing a part of the current generated by the generator 71 in accordance with a change in the charging current charged in the charging device 73. There is provided a constant current holding device 72 for holding a given current constant. This constant current holding device 7
2, the rotation load on the intermediate transfer body 21 generated by the generator 71 is kept constant, the fluctuation of the rotation speed of the intermediate transfer body 21 is suppressed, and the fluctuation of the speed of the electrostatic latent image carrier is suppressed.

In recent years, various environmental regulations have been set for the electrostatic recording type image forming apparatus due to the global movement for protecting the global environment. For example, New Blue Angel Mark, En
energy Star Program and the like. Of these regulations, for example, New Bl
According to ue Angel Mark, it is required for an image forming apparatus of an electrostatic recording system, for example, a printer, that the power consumption during standby be measured at a power plug and regulated to 2 W or less.

However, in recent image forming apparatuses, power consumption during standby tends to increase more and more due to demands for improvement in performance and functions. For example, the backup power of a memory for storing information required for printing, such as an image quality mode and a tone reproduction curve, is increasing, and various I / Fs represented by a network I / F are also increasing. It is becoming increasingly difficult to reduce the power consumption during standby to below the environmental regulation value as described above, such as the need for new power consumption such as power supply to the vehicle.

Therefore, in a third embodiment described below, the electric power generated by the generator 71 provided in the rotational speed fluctuation suppressing device 70 (see FIG. 5) can be utilized as the electric power at the time of standby. The image forming apparatus further includes a control circuit for controlling the power stored in the charging device to be supplied as standby power when the image forming apparatus is in a standby state in which an image forming operation is not performed. With this control device, the power stored in the charging device can be reused as standby power so that the above environmental regulation values can be cleared, and the rotational speed fluctuation of the toner image carrier during image formation is suppressed. can do.

FIG. 6 is a schematic configuration diagram of a third embodiment of the present invention. FIG. 6 shows a drum-shaped intermediate transfer body 21,
A motor 51 for driving the drive shaft 22 of the intermediate transfer body 21 via a gear group 56, a generator (not shown) connected to the drive shaft 22 of the intermediate transfer body 21, and the power generated by the generator is stored. A charging device 83 and a rotation speed fluctuation suppression device 80 including a control circuit 81 that controls so that power stored in the charging device 83 is supplied as standby power during standby are shown.

The control circuit 81 controls the entire power supply circuit 90 of the image forming apparatus including a main power supply circuit 91 and a backup power supply circuit 92. The main power supply circuit 91 supplies power from a commercial power supply to each device that operates during image formation in which normal image formation is performed, and the backup power supply circuit 92 includes a memory that operates when the image forming apparatus is on standby and various I / Os.
The power stored in the charging device 83 is supplied to the minimum number of devices including the / F circuit and a part of the control circuit 81.

The rotational speed fluctuation suppressing device 80 thus configured operates as follows. That is, at the time of normal image formation, the control circuit 81 controls the main power supply circuit 91 so as to supply electric power from the commercial power supply to each device operating at the time of image formation, and also controls the electric power generated by the generator (not shown). The backup power supply circuit 92 is controlled so as to be stored in the charging device 83. At this time, the backup power supply circuit 92 checks the charging status of the charging device 83 and supplies the charging device 8 with a minimum necessary device in standby.
3 and the electric power from the commercial power supply. In this way, the control circuit 81 performs control so as to minimize the power supply from the commercial power supply and also secure standby power so that the environmental regulation value can be cleared with a margin.

Here, at the time of image formation, control may be performed so that power is supplied only to the minimum necessary equipment at the time of standby using only the power from the charging device 83. In this case,
When the power supply to the above-described minimum necessary equipment cannot be continued with only the power from the charging device 83, the main power supply circuit 9
It is necessary to configure the control circuit 81 so as to switch to the power supply from No. 1.

When the control circuit 81 detects the transition from the image forming state to the standby state, the control circuit 81 controls the main power supply circuit 91 so as to stop the power supply to each device that operates at the time of image forming, and performs charging. The backup power supply circuit 92 is controlled so that the electric power stored in the device 83 is supplied to the operation device at the time of standby. At this time, the backup power supply circuit 92 supplies the power from the power storage means 63 and the power from the power supply circuit 72 to the operating device in the standby state while checking the charging status of the charging device 83.

In this way, while minimizing the power supply from the commercial power supply, various environmental regulation values are cleared with a margin. Further, the present invention can be applied to an image forming apparatus having a plurality of intermediate transfer members as described below. FIG. 7 is a schematic configuration diagram of another color printer to which the image forming apparatus of the present invention is applied.

As shown in FIG. 7, this color printer 2
At 00, electrostatic latent image carriers 3a and 3b on which electrostatic latent images of yellow (Y) and magenta (M) are formed, respectively.
It is arranged in contact with the intermediate transfer member 21a at each of the primary transfer positions T11 and T12 on the circumference of the intermediate transfer member 21a rotating in the direction of arrow A. The electrostatic latent image carrier 3 on which electrostatic latent images of cyan (C) and black (K) are formed
c, 3d at the respective primary transfer positions T13, T14 on the circumference of the intermediate transfer body 21b rotating in the direction of arrow A.
1b. Each electrostatic latent image carrier 3a,
The chargers 2a, 2b, 2c, and 2d for uniformly charging the surfaces of the respective electrostatic latent image carriers are provided on the surfaces 3b, 3c, and 3d, respectively. An electrostatic latent image forming apparatus 1a, 1b, 1c, 1d for forming a latent image, and an electrostatic latent image formed on the surface of each electrostatic latent image carrier is developed with the toner of each color described above to form a toner image of each color. Developing device 4 for forming
a, 4b, 4c, 4d, and cleaners 5a, 5b, 5c, 5d for cleaning the surfaces of the respective electrostatic latent image carriers.

The intermediate transfer member 21a is provided with an electrostatic latent image carrier 3
This is for receiving the primary transfer of the toner image of each color formed on the intermediate transfer member 21a on the circumference of the intermediate transfer member 21a. Secondary transfer position T2 downstream of transfer position T11
1 is provided with an intermediate transfer member 21c which receives a transfer from the intermediate transfer member 21a, in contact with the intermediate transfer member 21a.

The intermediate transfer member 21b is for receiving the primary transfer of the toner images of the respective colors formed on the electrostatic latent image carriers 3c and 3d and for secondary transfer to the intermediate transfer member 21c. , The primary transfer position T on the circumference of the intermediate transfer body 21b
At a secondary transfer position T22 on the downstream side of No. 13, it is in contact with the intermediate transfer member 21c which receives the transfer from the intermediate transfer member 21b.

Further, a secondary transfer position on the circumference of the intermediate transfer member 21c for tertiary transferring the toner images of each color secondary-transferred on the intermediate transfer member 21a and the intermediate transfer member 21b to the transfer medium P. At a tertiary transfer position T3 downstream of T22, a transfer roll 25 that rotates in the direction of arrow C in contact with the intermediate transfer member 21c is provided. Also, the intermediate transfer member 21c
The intermediate transfer member 21c is located downstream of the tertiary transfer position T3.
Is provided with a cleaner 6 for cleaning the surface of. Further, the color printer 200 is provided with a fixing device 31 for fixing the toner image transferred to the transfer medium P.

The thus constructed color printer 20
0, 3 and 5, all or some of the three intermediate transfer members 21a, 21b and 21c
By attaching a rotation speed fluctuation suppression device as described with reference to, and applying a braking force to those intermediate transfer members, fluctuations in the rotation speed of each electrostatic latent image carrier can be suppressed.

In each of the above embodiments, an example is shown in which the present invention is applied to an image forming apparatus in which the transfer device and the fixing device are configured as separate devices, but the present invention is not limited to this configuration. Instead, the present invention can be applied to an image forming apparatus of a so-called simultaneous transfer fixing method. In each of the embodiments described above, only examples in which the braking force is applied to the drive shaft of the intermediate transfer member to suppress the fluctuation in the rotation speed of the electrostatic latent image carrier are described. A braking force may be applied to the drive shaft of the electrostatic latent image carrier to directly suppress the rotation speed fluctuation of the electrostatic latent image carrier.

The present invention also relates to a four-cycle type color image forming apparatus including one electrostatic latent image carrier and a plurality of developing devices disposed around the electrostatic latent image carrier, and a monochrome image forming apparatus. The present invention can be applied to an image forming apparatus.

[0046]

As described above, according to the image forming apparatus of the present invention, the rotation speed fluctuation suppressing means for applying a braking force to the toner image carrier, that is, the electrostatic latent image carrier or the intermediate transfer member, is provided. As a result, fluctuations in the rotation speed of the electrostatic latent image carrier are suppressed, and image defects such as uneven density, color shift, and smear can be prevented from occurring in the finally obtained image.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a color printer to which an image forming apparatus of the present invention is applied.

FIG. 2 is a schematic configuration diagram of a rotation speed fluctuation suppressing device provided in the first embodiment of the present invention.

FIG. 3 is a graph showing a speed fluctuation of an intermediate transfer member when the rotation speed fluctuation suppressing device shown in FIG. 2 is not operated.

FIG. 4 is a graph showing a speed fluctuation of the intermediate transfer member when the rotation speed fluctuation suppressing device shown in FIG. 2 is operated.

FIG. 5 is a schematic configuration diagram of a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of another color printer to which the image forming apparatus of the present invention is applied.

[Explanation of symbols]

 1a, 1b, 1c, 1d Electrostatic latent image forming device 2a, 2b, 2c, 2d Charger 3a, 3b, 3c, 3d Electrostatic latent image carrier 4a, 4b, 4c, 4d Developing device 5a, 5b, 5c 5d, 6 Cleaner 21, 21a, 21b, 21c Intermediate Transfer Body 22 Drive Shaft 25 Transfer Roll 31 Fixing Device 31a Heating Roll 31b Pressing Roll 51 Motor 56 Gear Group 60, 70, 80 Rotational Speed Fluctuation Suppressor 61, 71 Generator 62 variable resistor 72 constant current holding device 73 charging device 81 control circuit 83 charging device 90 power supply circuit 91 main power supply circuit 92 backup power supply circuit 100, 200 color printer

Claims (4)

[Claims] A toner image bearing member which carries the toner image and rotates in a predetermined direction, transfers the toner image on the toner image bearing member to a predetermined recording medium, fixes the toner image on the recording medium, and fixes the image on the recording medium. In the image forming apparatus, a rotation speed fluctuation suppression unit that suppresses fluctuation of the rotation speed of the toner image carrier by applying a braking force to the toner image carrier, the rotation speed fluctuation suppression unit includes: An image forming apparatus comprising: a generator connected to a drive shaft of the toner image carrier; and a load that consumes power generated by the generator. 2. The image forming apparatus according to claim 1, wherein the load provided in said rotation speed fluctuation suppressing means includes a variable resistor. 3. A load provided in the rotational speed fluctuation suppressing means, comprising: a charging device for storing electric power generated by the generator; and a generator according to a change in a charging current charged in the charging device. 2. The image forming apparatus according to claim 1, further comprising: a constant current holding device that holds a current generated by the generator constant by bypassing a part of the generated current. 4. A control circuit for controlling the image forming apparatus to supply power stored in the charging device as standby power when the image forming apparatus is in a standby state in which an image forming operation is not performed. The image forming apparatus according to claim 3, wherein