JPH08305105A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device capable of making it difficult for a change in load on a recording-medium carrying system to exert effect on a photoreceptor and an intermediate transfer belt to which a toner image is primarily transferred from the photoreceptor, and capable of avoiding the use of a large motor. CONSTITUTION: The photoreceptor 5 and intermediate transfer belt 14 are rotated and driven by a first drive motor 41. The recording-medium carrying system 34 for carrying transfer paper 17 to a pair of fixing rollers 24, via a secondary transfer area 12, from a pair of resist rollers 18 is rotated and driven by a second drive motor 42 which is separate from the motor 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier which is rotationally driven, an intermediate transfer rotary member which is in contact with the image carrier and is rotationally driven in the same direction as the image carrier at the contact portion, and an image. First transfer means for transferring the toner image formed on the carrier to the intermediate transfer rotator, second transfer means for transferring the toner image transferred on the intermediate transfer rotator to the recording medium, and recording medium The recording medium before transfer is conveyed to the transfer area where the transfer is performed by the second transfer means by being rotationally driven by the fixing means for fixing the upper transfer toner image and the recording medium after transfer. The present invention relates to an image forming apparatus including a recording medium conveying system that conveys a sheet toward a fixing unit.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, a toner image formed on an image carrier is primarily transferred onto an intermediate transfer rotator and the transferred toner image on the intermediate transfer rotator is transferred. Further, an image forming apparatus of the above-mentioned type in which secondary transfer is performed on a recording medium is well known in the art. In this type of image forming apparatus, for example, a recording medium such as transfer paper is conveyed to a secondary transfer area at a predetermined timing by a pair of registration rollers, and the recording medium after transfer is conveyed to, for example, a recording medium conveying belt. The sheet is conveyed toward the fixing unit by the conveying device. In this way, the recording medium is conveyed before and after the transfer area by the recording medium conveying system including the registration rollers and the recording medium conveying belt.

Conventionally, such a recording medium carrying system, an image carrier, and an intermediate transfer rotator have generally been rotationally driven by a single drive motor. However, with such a drive system, when the rotation of a rotating element such as a registration roller is interrupted using a clutch or the like,
When the clutch is switched on / off, load fluctuations occur in the rotation of the drive motor, and the effects of these fluctuations affect the image carrier and intermediate transfer rotary member that must be rotated with high precision, and image blurring may occur. As a result, the image quality is likely to deteriorate. Since toner images are formed on the surfaces of the image carrier and the intermediate transfer rotator, the toner images will be blurred unless they are rotationally driven with high precision so as to prevent uneven rotation.

If the recording medium conveying system, the image carrier and the intermediate transfer rotator are driven to rotate by a single drive motor, not only a large motor is required, but also the image carrier and the intermediate transfer rotator. Therefore, a high-precision motor is required, which inevitably causes the drawback of increasing the cost of the image forming apparatus.

Therefore, the image carrier, the intermediate transfer rotary member,
It has also been conventionally practiced to drive the recording medium transport system and a dedicated drive motor, respectively. According to this driving method, the image carrier and the intermediate transfer rotator are not affected by the load fluctuation of the recording medium conveyance system.
By using high-precision motors for the image carrier and each motor for the intermediate transfer rotator, it is possible to prevent the toner image formed on each surface thereof from blurring. However, this drive method requires dedicated drive motors for the image carrier, the intermediate transfer rotator, and the recording medium transport system.
The number of motors increases, and the cost of the image forming apparatus increases significantly.

On the other hand, although it has already been described that the recording medium conveying system conveys the recording medium after transfer toward the fixing means, such a recording medium may be an overhead projector sheet (OHP sheet) or thick paper. When used, it is necessary that the time for them to pass through the fixing means, that is, the fixing time is longer than that when a normal transfer medium is used. Therefore, conventionally, when an overhead projector sheet or thick paper is used as the recording medium, all rotations of the image carrier, the intermediate transfer rotator, and the recording medium conveyance system are more than those when a normal recording medium is used. The drive speed is slowed down and a recording medium such as thick paper is conveyed at a low speed, and the time for the recording medium to pass through the fixing means is lengthened. However, according to this configuration, the operating speeds of the image carrier, the intermediate transfer rotator, and the recording medium conveying system are all slowed down.
The time required to perform an image forming operation on a recording medium such as a sheet of thick paper becomes long, and the speed of the image forming operation is unavoidably slowed down.

Therefore, when a special recording medium such as a sheet for overhead projector or thick paper is used, after the toner image is secondarily transferred onto the recording medium, the driving speed of the recording medium conveying system is reduced to fix the recording medium. It has been proposed to take a sufficient amount of time. With this driving method, the image carrier and the intermediate transfer rotator are rotationally driven at the same speed as when a normal recording medium is used until the secondary transfer of the toner image onto the recording medium is completed. The time required for the forming operation can be made shorter than in the case of the conventional example described above.

However, if this driving method is adopted, it is necessary to configure the front end of the recording medium to enter the fixing means after the rear end of a special recording medium such as thick paper passes through the secondary transfer area. Therefore, the conveyance distance of the recording medium from the secondary transfer area to the fixing unit becomes long, and the image forming apparatus becomes large.

[0009]

SUMMARY OF THE INVENTION A first object of the present invention is to prevent the image carrier and the intermediate transfer rotator from being affected by the load fluctuation of the recording medium conveying system, and to provide a large motor. It is an object of the present invention to provide an image forming apparatus capable of avoiding the use of the motor and reducing the number of the motors as much as possible.

A second object of the present invention is to prevent a remarkably long time required for the image forming operation even when a special recording medium which requires a longer time than usual for fixing is used. Moreover, it is an object of the present invention to provide an image forming apparatus which does not require a particularly long recording medium conveyance distance from a region for transferring a toner image from an intermediate transfer rotator to a recording medium to a fixing unit.

[0011]

In order to achieve the above first object, the present invention provides an image forming apparatus of the type described at the beginning, in which the image carrier and the intermediate transfer rotary member are the same rotary drive source. A configuration is proposed in which the recording medium transport system is rotatably driven by each of the first drive motors, and the recording medium transport system is rotatably driven by the second drive motor that is a rotary drive source different from the rotary drive source.

Further, in order to achieve the above second object, the present invention provides an image forming apparatus of the type described at the beginning when the fixing time is set longer than the normal fixing time.
After the completion of the transfer by the transfer means and before the start of the transfer by the second transfer means, the rotational driving speed of the image carrier and the intermediate transfer rotator ends the transfer by the first transfer means. The rotation drive speed of the image carrier and the intermediate transfer rotation body is switched so that the rotation speed is lower than the rotation drive speed up to, and the rotation speed of the recording medium conveyance system is slower than the rotation drive speed when the fixing time is not set long. We propose a configuration including a control drive unit that rotates at a drive speed in synchronization with the intermediate transfer rotary member whose rotation drive speed is reduced.

In this case, in the above structure, the control drive means includes a first drive motor, which is the same rotary drive source for rotationally driving the image carrier and the intermediate transfer rotor, respectively, and the recording medium transport system. The second, which is a rotary drive source for rotary drive
It is advantageous to have a drive motor of

[0014]

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

FIG. 1 is a schematic configuration diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus 1
Has a document reading unit 4, a system control unit 3, and a printer unit 2. The system control unit 3 includes the document reading unit 4
In addition, the printer unit 2 is integrally controlled.

First, the schematic structure of the printer unit 2 will be described.
Drum-shaped photoreceptor 5 which is a main component of the printer unit 2
Is an example of an image carrier, and the photoconductor 5
Is driven to rotate counterclockwise in the figure by a drive motor described later. During this rotation, the surface of the photoconductor 5 is uniformly charged by the action of the charging charger 6 which is an example of a charging device. Next, in the exposure unit 7, the laser beam 9 emitted from the laser beam writing system 8 performs optical writing scanning, whereby a predetermined electrostatic latent image is formed on the photoconductor 1. It is also possible to form the light image from the original directly on the photoconductor to form an electrostatic latent image.

The electrostatic latent image is first converted into a black toner image by a black developing device B of a rotary developing device 13 having a black developing device B, a yellow developing device Y, a magenta developing device M and a cyan developing device C. To be visualized. The intermediate transfer belt 14, which is an example of the configuration of the intermediate transfer rotator, is configured to be driven to rotate in the clockwise direction in the figure, and the black toner image is transferred to the intermediate transfer belt 14 in the primary transfer area 11.
Then, the primary transfer is performed by the action of the transfer charger 15.

After the above-mentioned formation of the electrostatic latent image, another color-separated electrostatic latent image is sequentially formed on the photoconductor 5 which continues to rotate. Each time the electrostatic latent image is formed, another developing device Y of the rotary developing device 13,
The toner images of yellow, magenta, and cyan are sequentially formed by M and C, respectively.
A full-color toner image is formed on the intermediate transfer belt 14 by sequentially and secondarily transferring the toner images of the respective colors onto the first transferred black toner image. The toner images of the respective colors on the photoconductor 5 are transferred onto the intermediate transfer belt 14
The toner remaining on the photoconductor 5 after being transferred to the photoconductor 5 is cleaned and removed from the photoconductor 5 by the cleaning device 31.

On the other hand, from the paper feed tray 16, a transfer paper 17, which is an example of a recording medium, is rotated by a paper feed roller 19 and passes through a transport roller pair 20 and then a registration roller pair 1.
Sent to 8. The transfer paper 17 whose front end has reached the registration roller pair 18 is secondarily transferred by the rotation of the registration roller pair 18 between the front end of the full-color toner image on the intermediate transfer belt 14 and the front end of the transfer paper 17. Area 12
To the transcribed region 12 so as to associate with each other. Transfer paper 17 sent toward secondary transfer area 12
, The full-color toner image on the intermediate transfer belt 14 is secondarily transferred by the action of the transfer charger 21.
After this transfer, the transfer paper 17 is separated from the intermediate transfer belt 14 by the action of the separation charger 22.

The conveyor belt 23 includes a pair of rollers 23A,
It is hung between 23B and is rotationally driven in the counterclockwise direction in the figure. The transfer paper 17 separated from the intermediate transfer belt 14 is sent toward the fixing roller pair 24 constituting the fixing means by the rotation of the transport belt 23.

The fixing roller pair 24 is a heat fixing roller 24A.
The heat fixing roller 24A among them is driven to rotate in the direction of the arrow in the drawing, and the pressure roller 24B is also driven to rotate in the direction of the arrow. While the transfer paper 17 passes between these rotating rollers, the transfer toner image on the transfer paper is fixed. After this fixing, the transfer sheet is conveyed toward the sheet discharge tray 27 by the rotation of the pair of conveying rollers 25 and the pair of discharging and conveying rollers 26,
The full-color copy paper is stored in the tray 27.

In the case of a monochromatic copy, the toner images of a plurality of colors are not superposed and transferred, but the monochromatic toner images are transferred from the photoconductor 5 to the intermediate transfer belt 14, and the intermediate transfer belt 1 is further transferred.
The transfer toner image on the sheet 4 is transferred onto the transfer paper, and the monochromatic copy paper is ejected to the paper ejection tray 27.

In the image forming apparatus of this example,
Manual feeding from the manual feeding table 28 is also possible. When manually feeding, the manual feeding table 28 is laid down sideways, and the leading end side of the transfer sheet is inserted below the feeding roller 29 along the table surface. Then, the feeding roller 29 rotates, and the transfer sheet is sent toward the registration roller pair 18 via the pair of conveyance rollers 30.

In addition, a cleaning device 32 for the intermediate transfer belt is provided opposite to the intermediate transfer belt 14, and the toner image is secondarily transferred from the intermediate transfer belt 14 to the transfer paper 17 and then remains on the intermediate transfer belt 14. The toner is cleaned by the cleaning member 32a of the cleaning device 32. The collected toner is conveyed and discharged to the outside of the case of the cleaning device by a toner conveying member composed of the toner conveying screw 33 of the cleaning device 32. The cleaning member 32a is configured to be separated from the intermediate transfer belt 14 at a time other than the time of cleaning the intermediate transfer belt 14 so as not to disturb the toner image on the intermediate transfer belt 14.

Next, the document reading section 4 will be described. The contact glass 14 installed on the upper part of the housing.
A document (not shown) is placed and set at 0, and the optical system including the document illumination lamp 141 and the first mirror 142 and the optical system including the second and third mirrors 143 and 144 are 2: 1 respectively. When driven to the right in FIG. 1 at the speed ratio, the original placed on the contact glass 140 is
Reading and scanning are performed by these optical systems. And
The scanning light image at this time is projected through the imaging lens 150 onto the reading element 145 composed of, for example, a CCD, and the image information of the document is read. Such image information is reproduced as a recorded image on the transfer paper 17 in the printer unit 2 as described above.

In FIG. 1, the photosensitive member 5 constitutes one example of the constitution of the image carrier which is rotationally driven as described above, and the intermediate transfer belt 14 contacts the image carrier and its contact portion. In, an example of an intermediate transfer rotator that is rotationally driven in the same direction as the image carrier is configured. The intermediate transfer belt 14 is rotationally driven so that the belt part in contact with the photoconductor 5 moves in the same direction as the moving direction of the photoconductor part in contact with this belt part. In contact with each other, they are rotationally driven in the same direction as the photoconductor 5. An image carrier composed of an endless belt can be used, and an intermediate transfer rotary member composed of a drum can also be used.

The transfer charger 15 transfers the toner image formed on the image carrier composed of the photoconductor 5 to the intermediate transfer belt 14.
An example of a first transfer unit that transfers to an intermediate transfer rotator is formed. In addition, the transfer charger 21 constitutes an example of a second transfer unit that transfers the toner image transferred onto the intermediate transfer rotating body composed of the intermediate transfer belt 14 onto a recording medium such as transfer paper. Instead of the chargers 15 and 21, a transfer means such as a transfer roller may be adopted.

The fixing roller pair 24 constitutes an example of fixing means for fixing the transferred toner image on the recording medium such as transfer paper after the secondary transfer by the second transfer means is completed. Further, the recording medium conveying system 34 including the registration roller pair 18 and the conveying belt 23 is rotationally driven, and the recording medium before transfer is transferred to the secondary transfer area where the second transfer means transfers the recording medium. The recording medium after being transferred is also transported toward the fixing means 12 composed of a pair of fixing rollers 24. In the case of the present embodiment, the transfer medium 17 is conveyed in the vicinity of the secondary transfer area 12 by the recording medium conveying system 34 including the registration roller pair 18 and the conveying belt 23.

Here, the feature of this example is that the image carrier and the intermediate transfer rotator are rotationally driven by the first drive motor, which is the same rotational drive source, respectively.
The recording medium transport system is rotatably driven by a second drive motor which is a rotary drive source different from the rotary drive source. The image forming apparatus has a first drive motor that rotationally drives both the image carrier and the intermediate transfer rotator, and a second drive motor that drives the recording medium transport system.

In FIG. 2, the reference numeral 41 is the first drive motor, and the reference numeral 42 is the second drive motor. In the figure, an endless intermediate transfer belt 1
4 is a driving roller 35 and driven rollers 36, 37, 38, 3
It has been passed over between nine. The drive roller 35 is provided with a gear 35A coaxially and integrally. Further, the photoconductor 5 is also provided with a gear 5A coaxially and integrally.

The rotation of the drive motor 41 is transmitted to the photoconductor 5 and the intermediate transfer belt 14 via the rotating elements described below.

That is, the motor gear 4 of the drive motor 41
A large-diameter gear 43 meshes with 1A, and another large-diameter gear 45 meshes with a small-diameter gear 44 that is coaxial with the gear 43. Small diameter gear 46 coaxial with large diameter gear 45
Gears 47 and 48 mesh with each other. One gear 47 meshes with the photoconductor gear 5A, and the other gear 48 meshes with the gear 49. The gear 49 meshes with the drive roller gear 35A.

When the motor gear 41A of the drive motor 41 rotates in the direction of arrow a, the photoconductor 5 and the intermediate transfer belt 14 are rotationally driven in the direction of arrow in the figure via the transmission gears described above. That is, the photoconductor 5
And the intermediate transfer belt 14 are the same rotary drive source.
The drive motors 41 of FIG.

On the other hand, the rotation of the second drive motor 42 is transmitted to the recording medium carrying system 34 via the transmitting element system described below. That is, the motor gear 42A of the drive motor 42
Is rotated in the direction of the arrow b, the rotation is transmitted through the idle gears 49, 50, 51, 52, 53 to the drive roller 2
It is transmitted to a drive roller gear 54 which is coaxial with 3A, and this gear 54 is rotationally driven counterclockwise in the drawing. As a result, the conveyor belt 23 is rotationally driven counterclockwise in the figure.

When the fixing roller pair 24 is used as the fixing means as illustrated in FIG. 2, this also applies to the recording medium conveying system 3.
It can be regarded as one of the four constituent elements. Another gear 55 meshes with the gear 52 described above, an idle gear 56 meshes with the gear 55, and a fixing roller gear 57 coaxial with the heat fixing roller 24A meshes with the gear 56. When the gear 55 engaged with the gear 52 rotates in the direction of the arrow in the drawing, the fixing roller gear 57 rotates via the gear 56, and the heat fixing roller 24A rotates clockwise in the drawing. Along with this, the lower pressure roller 24B is driven to rotate counterclockwise in the drawing. Pressure roller 24
B is rotationally driven by a second drive motor 42 via a gear (not shown), or both rollers 24A, 24
Both B may be configured to be rotationally driven by the drive motor 42 via each gear.

In this example, the pair of transport rollers 25 shown in FIG.
The rotation from the second drive motor 42 is also transmitted to the pair of discharge and conveyance rollers 26 via a transmission element (not shown).
It is rotationally driven in the direction shown by the arrow in FIG.

On the other hand, a gear 58 meshes with the motor gear 42A. A pulley 59 coaxial with the gear 58
An endless timing belt 65 is stretched between the pulleys 60 and 61 and a predetermined tension is applied to the timing belt 65 by a tension applying pulley 66.

When the motor gear 42A rotates, the gear 58
The drive pulley 59 rotates via the
5 is driven to rotate clockwise in the drawing. A gear 62 is coaxially provided on the driven pulley 61.
Meshes with an idle gear 63, and this gear 63 meshes with a roller gear 64 that is coaxial with the registration roller 18A. When the driven pulley 61 rotates, the roller gear 64 rotates via the gear 62 and the gear 63, and the registration roller 18A rotates clockwise in the drawing. In the illustrated example, the lower registration roller 18B rotates following the rotation of the registration roller 18A, but the lower registration roller 18B is also rotated by the second drive motor 42 via a gear. It is also possible to configure.

A clutch (not shown) is provided between the registration roller 18A and the roller gear 64. When the clutch is turned on, the rotation of the roller gear 64 which is normally rotating is transmitted to the registration roller 18A. The roller 18A rotates. At this time, the transfer paper is sent from the registration roller pair 18 toward the secondary transfer area 12. Further, in this example, the transport roller pair 20 also constitutes one component of the recording medium transport system 34, and the roller pair 20 is also transmitted with the rotation from the second drive motor via a transmission element (not shown). It is driven to rotate. Further, using the second drive motor 42 as a drive source, the paper feed roller 19 and the feed roller 2
9, the conveying roller pair 30 and the like may be rotationally driven. In this case, the paper feeding roller 19, the feeding roller 29, and the conveying roller pair 30 are also components of the recording medium conveying system 34. The recording medium transport system 34 is rotationally driven by the second drive motor 42 as described above.

The cleaning device 32 for the intermediate transfer belt includes the toner conveying screw member 3 as described above.
3 is provided, and the collected toner is conveyed to the outside of the cleaning device by the rotation of the toner conveying screw member 33. At that time, the gear 67, which is coaxial with the pulley 60, causes the toner carrying screw member 33 to move.
Is meshed with a gear 33A that is coaxial with and the toner conveying screw member 33 is rotationally driven by such a transmission element system.

Further, in this embodiment, the entire developing device 13 and the developing rollers of the developing devices B, Y, M and C are the same as the above-mentioned first developing roller.
And a second drive motor (not shown) different from the second drive motors 41 and 42, respectively.

As described above, conventionally, one drive motor is used to drive the photoconductor 5, the intermediate transfer belt 14 and the recording medium carrying system 34. According to this, when the rotation of the rotating element such as the registration roller pair 18 is intermittently performed by using a clutch or the like, a load variation occurs in the rotation of the drive motor when the clutch is switched on and off, and thus the influence of this variation is exerted. The image quality easily deteriorates due to the occurrence of image blur and color misregistration of superposed images, which spreads over the photoconductor and the intermediate transfer belt that must be rotated with high precision. Further, not only a large-sized motor is required, but also a high-precision motor is required for the photoconductor 5 and the intermediate transfer belt 14, and the cost of the image forming apparatus is likely to increase.

Also, a configuration is known in which each of the photoconductor 5, the intermediate transfer belt 14 and the recording medium carrying system 34 is driven by a separate drive motor. However, according to this, a large number of drive motors are required and an image is formed. The cost of the device increases.

On the other hand, in the image forming apparatus 1 of this example, the motor 42 for driving the recording medium conveying system 34 is different from the motor 41 for driving the photoconductor 5 and the intermediate transfer belt 14. The influence of the load fluctuation of the recording medium conveying system 34 can be made less likely to be exerted on the photoconductor 5 or the intermediate transfer belt 14 which must be rotated with high accuracy.
As a result, the occurrence of image blurring and color misregistration is suppressed, so that it is possible to prevent deterioration of image quality.

Further, since the first drive motor 41 rotationally drives both the photoconductor 5 and the intermediate transfer belt 14, it is possible to prevent a problem that the number of motors provided in the image forming apparatus 1 increases unnecessarily. Even if the photoconductor 5 and the intermediate transfer belt 14 are driven by the common motor 41, they are not affected by the load fluctuation. If a relatively high-precision motor having no rotation unevenness is adopted as the first drive motor 41, the photosensitive member 5
Therefore, the toner image formed on the surface of the intermediate transfer belt 14 is not shaken. By properly using the motor in this way, the cost of the drive source can be reduced, and it is not necessary to employ a large motor. If the photoconductor 5 and the intermediate transfer belt 14 are driven by separate independent drive motors, the cost of the drive source increases. In this example, the drive sources of the photoconductor 5 and the intermediate transfer belt 14 are shared, and the cost of the drive source can be reduced.

By the way, a typical recording medium generally used is a transfer sheet cut into a predetermined size. However, as a recording medium, an overhead projector sheet or the same transfer sheet is also thick. Sometimes things are used. When such a special recording medium is used, the toner image cannot be surely fixed unless it takes a longer time for fixing than when using a normal recording medium.

Therefore, in the conventional case, the number 2 shown in FIG.
After the rear end of the special recording medium passes through the next transfer area 12, the driving speed of the recording medium transport system 34 is reduced to, for example, 1/2.
It has been proposed to reduce the speed. In this way, it is possible to spend a sufficient time for fixing by the fixing roller pair 24, and from the beginning, the photoconductor 5 and the intermediate transfer belt 14 are
Also, the time required for image formation can be shortened as compared with the case where all the driving speeds of the recording medium transport system 34 are set to low speeds. By switching the driving speed of the recording medium transport system 34, the fixing time can be lengthened and the time required for image formation can be shortened.

However, after the trailing edge of the recording medium has passed through the secondary transfer area 12, if the drive speed of the recording medium transport system 34 is reduced, the secondary transfer area 12 is fixed as described above. The distance to the roller pair 24 needs to be at least the length of the recording medium, and the distance needs to be set long. As a result, the image forming apparatus becomes large.

Therefore, in the image forming apparatus of the present embodiment, in addition to the above-mentioned constitutions, when the fixing time is set longer than the normal fixing time, the transfer by the first transfer means, that is, the primary transfer area 11 is performed. After the transfer is completed and before the transfer by the second transfer means, that is, the transfer in the secondary transfer area 12 is started, the intermediate transfer rotation composed of the image carrier made of the photoconductor 5 and the intermediate transfer belt 14 is performed. The rotational drive speed of the image carrier and the intermediate transfer rotary body is switched so that the rotational drive speed with respect to the body is lower than the rotational drive speed until the transfer by the first transfer unit is completed, and the recording medium is conveyed. The system 34 has a control drive unit that drives the system 34 at a rotational drive speed slower than the rotational drive speed when the fixing time is not set to be long, in synchronization with the intermediate transfer rotary member whose rotational drive speed is reduced.

In FIG. 2, assuming that the transfer paper 17 which is an example of the recording medium is a thick paper, when using this, it is necessary to take a longer time for fixing than when using a normal transfer paper. is there. The operation timing when the fixing time is set longer than the normal fixing time will be described below. First, the document reading operation described above,
The toner image is formed on the photoconductor 5 at the same high speed as when a normal transfer paper is used. That is, during this operation, the photoconductor 5 and the intermediate transfer belt 14 can execute the above-described image forming operation by the first drive motor 41 at the same high speed as in the case of using normal transfer paper. It is driven at the driving speed.

On the other hand, after the trailing edge of the full-color toner image on the intermediate transfer belt 14 passes through the primary transfer area 11, that is, the transfer charger 1 as the first transfer means.
5, after the secondary transfer of the toner image onto the intermediate transfer belt 14 is completed and before the front end portion of the full-color toner image reaches the secondary transfer area 12, that is, the transfer charger which is the second transfer unit. Before starting the secondary transfer of the toner image by 21, the control device (not shown) outputs a rotation speed switching signal to the first drive motor 41. Motor 41
Shifts to the low speed rotation mode. From this point on, the photoconductor 5 and the intermediate transfer belt 14 are rotationally driven at a slower speed than before, for example, half the speed up to then.
The photoconductor 5 and the intermediate transfer belt 14 are controlled so that the rotational drive speed between the photoconductor 5 and the intermediate transfer belt 14 is lower than the rotational drive speed until the transfer by the transfer charger 15 is completed by the control of the control device. The rotational drive speeds of and are switched.

On the other hand, also for the second drive motor 42,
A rotation speed switching signal is output to the temporary machine, the drive motor 42 is made slower than the rotation speed up to that in the case of using normal recording paper, and the low speed rotation mode is entered. Along with this, the recording medium carrying system 34 is rotationally driven at a slower speed than before, for example, half the speed. The recording medium conveying system 34 is driven in synchronization with the intermediate transfer belt 14 whose rotational speed has been reduced.

The full-color toner image on the intermediate transfer belt 14 whose speed has been reduced as described above is transferred to the secondary transfer area 12
Then, by the function of the registration roller pair 18, it is transferred to the transfer paper made of thick paper fed at the above-mentioned timing. That is, after the rotation speeds of the first and second drive motors 41 and 42 are switched, the thick transfer paper 17 undergoes the secondary transfer at a slower speed than the case of using the normal transfer paper. The secondary transfer is carried at a slow speed while being conveyed through the area 12. Conveyor belt 2 at the same speed after this
3, the transfer toner image on the transfer paper is fixed while passing through the fixing roller pair 24 which is rotated at a slow speed. In this way, the transfer toner image is fixed over a longer period of time than the normal transfer paper. Also in the single-color copy mode, the transfer paper is conveyed and fixed by a similar operation process. The recording medium transport system 34 may be driven at a low speed from the beginning without switching the driving speed as described above. With this configuration, the second drive motor 42 operates at a constant slow speed from the start to the end of the image forming operation on the thick paper, so that the control thereof becomes easy.

In any case, the recording medium carrying system 34
The rotational drive speed is lower than the rotational drive speed when the fixing time is not set to be long, and the rotational drive speed is synchronously driven with the intermediate transfer belt 14 whose rotational drive speed is reduced.

As described above, in the present embodiment, the above-mentioned control driving means is constituted by the image carrier composed of the photoconductor 5 and the intermediate transfer belt 1.
A first drive motor 41, which is the same rotary drive source that rotationally drives the intermediate transfer rotary member composed of 4; and a second drive motor 42, which is a rotary drive source that rotationally drives the recording medium transport system 34, It has the above-mentioned control device which controls these motors 41 and 42 as mentioned above.

According to the above construction, even when a special recording medium such as thick paper is used, the photosensitive member 5 and the intermediate transfer belt 14 are not driven at a slow speed from the start of the image forming operation. It is possible to suppress a decrease in the speed of the forming operation. Moreover, before the secondary transfer by the transfer charger 21 is started, the rotational driving speed of the photoconductor 5 and the intermediate transfer belt 14 is decreased, and the special recording medium is conveyed by the recording medium conveying system 34 having a speed synchronized with the speed. Even if the distance from the secondary transfer area 12 to the fixing unit is not particularly long, the toner image on the special recording medium can be reliably fixed over a long time, and the occurrence of the fixing failure can be prevented. In this way, it is possible to avoid the problem that the image forming apparatus becomes large.

[0057]

According to the image forming apparatus of the first aspect of the present invention, the influence of the load fluctuation of the recording medium conveying system is less likely to be exerted on the image carrier or the intermediate transfer rotator which must be rotated with high accuracy. As a result, it is possible to suppress the occurrence of image blurring and color misregistration of superimposed images, and prevent deterioration of image quality. Further, since only one drive motor is required to drive the image carrier and the intermediate transfer rotator, the cost of the drive source can be reduced, which in turn can reduce the cost of the image forming apparatus.

According to the image forming apparatus of the second aspect,
Even when using a special recording medium that requires a longer time for fixing than when using a normal recording medium, such fixing can be performed without any trouble, and the time required for the image forming operation can be reduced. You can prevent it from becoming long.
In addition, the recording medium conveyance distance from the secondary transfer area to the fixing unit does not have to be particularly long, which can avoid an increase in the size of the image forming apparatus.

According to the image forming apparatus of claim 3,
In addition to the effect obtained by the configuration of claim 2 described above,
The effect obtained by the configuration of claim 1 can also be obtained.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram showing driving devices such as the photoconductor, the intermediate transfer belt, a recording medium conveying system, and a fixing unit shown in FIG.

[Explanation of symbols]

 1 Image Forming Apparatus 12 Transfer Area 34 Recording Medium Conveying System 41 First Drive Motor 42 Second Drive Motor

Claims (3)

[Claims] 1. An image carrier which is rotationally driven, an intermediate transfer rotary member which is in contact with the image carrier and is rotationally driven in the same direction as the image carrier at the contact portion, and formed on the image carrier. First transfer means for transferring the toner image transferred onto the intermediate transfer rotator, second transfer means for transferring the toner image transferred on the intermediate transfer rotator onto a recording medium, and the transferred toner image on the recording medium. The recording medium before transfer is conveyed toward the transfer area where transfer is performed by the second transfer means by being driven to rotate by the fixing means for fixing and the recording medium after transfer is directed toward the fixing means. In an image forming apparatus including a recording medium conveying system for conveying, an image carrier and an intermediate transfer rotator are rotationally driven by a first drive motor that is the same rotational drive source, and a recording medium conveying system is also used. The rotation drive Image forming apparatus characterized by rotationally driving the second drive motor is another rotary drive source and. 2. An image carrier which is rotationally driven, an intermediate transfer rotary member which is in contact with the image carrier and is rotationally driven in the same direction as the image carrier at the contact portion, and formed on the image carrier. First transfer means for transferring the toner image transferred onto the intermediate transfer rotator, second transfer means for transferring the toner image transferred on the intermediate transfer rotator onto a recording medium, and the transferred toner image on the recording medium. The recording medium before transfer is conveyed toward the transfer area where transfer is performed by the second transfer means by being driven to rotate by the fixing means for fixing and the recording medium after transfer is directed toward the fixing means. In an image forming apparatus equipped with a recording medium conveying system for conveying, when the fixing time is set to be longer than the normal fixing time, after the transfer by the first transfer means is completed and the transfer by the second transfer means is completed. Image bearing before starting And such that the rotational drive speed of the intermediate transferring member is also dropped from the rotation drive speed until the end of the transfer by the first transfer means,
The rotational drive speed of the image carrier and the intermediate transfer rotary body is switched, and the rotational drive speed is slower than the rotational drive speed when the recording medium conveyance system is not set to a long fixing time. An image forming apparatus comprising: a control drive unit that is rotationally driven in synchronization with a transfer rotating body. 3. The first drive motor, which is the same rotary drive source for rotationally driving the image carrier and the intermediate transfer rotary member, and the rotary drive for rotationally driving the recording medium transport system. The image forming apparatus according to claim 2, further comprising a second drive motor that is a power source.