JP2005189469A - Imaging apparatus, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a transfer paper output speed and to realize high productivity while keeping single-layout constitution simple in mechanism, compact, lightweight, and inexpensive as compared with a tandem type. <P>SOLUTION: The figure shows that imaging of cyan is in progress and a developed image formed on a photoreceptor 17 is primarily transferred to a 1st intermediate transfer belt 181 and then secondarily transferred from the other end to a 2nd intermediate transfer belt immediately. In other words, the primary transfer and secondary transfer are carried out nearly simultaneously. During this period, other sectorial imaging units stand by in an outer circumferential direction. In processes up to when toner of all colors are put over the 2nd intermediate belt 182, images are formed at a process speed V1. After images of all the colors are put over the 2nd intermediate belt 182, the linear speed of the 2nd intermediate belt 182 is reduced from V1 to V2. The time-series speed reduction ratio from V1 to V2 is ≥2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, an image forming apparatus, and a process cartridge, and more particularly, to a single layout image forming apparatus, an image forming apparatus, and a process cartridge that use only one photoconductor.

  In recent years, digital PPC and page printers using an electrophotographic process are actively shifting from conventional monochrome to color and also to high-definition full-color printing. In particular, various so-called tandem layouts that use four photoconductors for high-speed output have been actively proposed, such as that of Patent Document 1 previously filed by the present applicant. These are four photoreceptors arranged in series.

Such a tandem layout image forming process is characterized in that latent image formation, visualization, and superposition of each color are performed in parallel, and are transferred onto a transfer medium almost simultaneously, enabling high-speed output.
On the other hand, the mechanism is complicated and has the disadvantages of being large, heavy and expensive. Also, adjustment is difficult because high image quality cannot be obtained unless the optical writing scanning lines on the photosensitive member are matched.

On the other hand, the single layout using one conventional photoconductor has features that the mechanism is simpler, more compact, lighter and cheaper than the tandem type. In addition, since optical writing on the photosensitive member is performed by one scanning line, the writing position deviation is very small in principle. High image quality can be obtained despite almost no adjustment.
On the other hand, since the latent image formation, visualization, and superposition of each color are performed serially in principle, the medium to be transferred waits during that time, and the transfer paper output speed becomes relatively low.

  Among the recent electrophotographic image forming apparatuses, the relationship between the productivity and the grade according to the size and price of the machine can be roughly shown in Table 1 below for the full-color electrophotographic system. V below is the process speed (≈photoconductor peripheral speed≈transfer medium (transfer paper) transport speed), and PPM / CPM (Print Per Minutes / Copy Per Minutes) is the number of A4 horizontal outputs per minute.

  When trying to correspond to the process speed shown in Table 1 above, the scanning speed of the optical writing unit that writes a latent image on the photosensitive member becomes one bottleneck for the increase in speed. The bottleneck is improved by using a multi-beam writing method as disclosed in Patent Document 2 by the applicant of the present application, and a plurality of scanning lines are simultaneously written by the multi-beam method for a medium speed machine or more in recent years. Devices are becoming particularly common.

Another similar bottleneck is the upper limit of the rotation speed of the polygon motor; motor bearing system (fluid bearing, magnet bearing, air bearing, etc.), high dependence on thermal / time-dependent durability, and The upper limit rotational speed is also related to the number of light sources described above.
The relationship between the number of light sources in recent years and the rotation speed of the polygon motor in the electrophotographic image forming apparatus can be roughly shown in Table 2 below.

An example of such a conventional single layout image forming apparatus is shown in FIG.
In the conventional example shown in FIG. 6, only one photosensitive drum 817 is used as an image carrier, and charging-exposure-development (yellow, cyan, magenta, and black are sequentially visualized by revolver rotation) -primary transfer. -The secondary transfer is performed. Color image formation is performed in four cycles in the intermediate transfer belt overlapping process, and each color of yellow, cyan, magenta, and black is superimposed on the intermediate transfer belt 818 (primary transfer).
Incidentally, the peripheral length of the intermediate transfer belt 818 is required to be 420 mm or more if it corresponds to A3 longitudinally fed transfer paper, and it is preferable that there is a belt peripheral length of 500 mm to 600 mm with a margin.

The transfer paper is appropriately conveyed from the paper feed tray 81 and waits with the leading end gripped by the registration roller 820 to transfer the image. After all color images are superimposed on the belt 818, the driving of the registration roller is turned on, and the image is transferred (secondary transfer) to a transfer medium (cut sheet or the like) from here.
JP 2000-221750 A Japanese Patent No. 3441577

As described above, in the conventional single-layout image forming apparatus described above, in principle, the transfer sheet must wait in front of the transfer unit until a plurality of cycles of the process of forming each color is completed. The speed is relatively low.
On the other hand, the mechanism is simple as a beauty point not found in the tandem layout, and it is compact, lightweight and inexpensive, and optical writing to the photoconductor is performed by one scanning line, so that the writing position deviation is very small in principle. High image quality can be obtained despite almost no adjustment.

  The present invention has been made in view of such a situation, and has a single layout configuration, which is simpler than a tandem type, and can improve the output speed of a transfer paper while keeping it compact, lightweight, and inexpensive. It is an object of the present invention to provide an image forming apparatus, an image forming apparatus, and a process cartridge capable of realizing high productivity.

  To achieve this object, an image forming apparatus according to a first aspect of the present invention includes only one image carrier, at least one writing unit for forming a latent image on the image carrier, and an image carrier. An image forming apparatus comprising: at least two developing units for forming a visible image on the surface; and at least two transfer units for transferring the visible image to a transfer medium, wherein at least 2 transfer from the image carrier to the transfer unit is performed. It is performed at a location.

  As the transfer unit described above, at least two first transfer units and at least one second transfer unit are provided, and transfer from the first transfer unit to the second transfer unit is performed in at least two places. Is preferred.

The writing unit described above is an optical scanning device, and the light source of the optical scanning device is preferably configured as a multi-beam system. The number of light sources of the optical scanning device is preferably 4 or more.
Further, the writing unit described above may be configured as an LED array type.

ただし、
Ｖ１：第１の作像速度
Ｖ２：第２の作像速度 The first image forming speed and the second image forming speed are controlled at the time of image forming on one transfer medium, and the first image forming body, the writing unit, the developing unit, and the transfer unit described above are controlled. A visible image is formed by the image speed, and the visible image is transferred from the transfer unit to the transfer medium by the second image forming speed, and the first image forming speed (V1) and the second image forming speed are transferred. It is preferable that (V2) satisfies the following formula (S1).

However,
V1: First image forming speed V2: Second image forming speed

At least two image forming units each including at least two developing units for forming a visible image on the image carrier and at least two transfer units for transferring the visible image to a transfer medium are provided. It is preferable that the units are arranged circumferentially around the image carrier.
It is preferable that at least two of the charging unit, the cleaning unit, and the charge eliminating unit are provided outside the image forming unit.

  An image forming apparatus according to a second aspect of the present invention includes the above-described image forming apparatus according to the first aspect of the present invention and a transfer medium supply unit that supplies a transfer medium. It is characterized by performing.

  The process cartridge according to the third aspect of the present invention integrally supports at least one of the charging means, the developing means, and the cleaning means and the image carrier, and the above-described second aspect of the present invention. The image forming apparatus main body is configured to be detachable.

  As described above, according to the present invention, the single-layout configuration is simpler than the tandem type, and the transfer paper output speed can be improved while keeping it compact, lightweight, and inexpensive. Can be realized.

Next, an image forming apparatus, an image forming apparatus, and a process cartridge according to the present invention will be described in detail with reference to the drawings.
First, each embodiment of an image forming apparatus used as a main part of an image forming apparatus according to the present invention will be described.

FIG. 1 shows an outline of the configuration of a revolver type image forming apparatus as a first embodiment of the present invention.
The photoconductor 17 is positioned on a structure of an image forming apparatus (not shown) and is fixed except in the rotation direction. A revolver type image forming device 50 is configured that rotates as a whole around the photoconductor drum 18, and the revolver type image forming device 50 includes the photoconductor 17 and four fan-shaped image forming units 500 each having a fan-shaped cross section; Y), magenta (M), cyan (C), and black (Bk) toner images are visualized on the photosensitive member 17.
Each color fan-shaped image forming unit 500 includes a developing unit 501 and a decharging / cleaning unit 502.

  Further, the first intermediate transfer belt 181 for transferring the visible image on the photosensitive member 17 to the transfer medium is a fan shape of each color of yellow (Y), magenta (M), cyan (C), and black (Bk). The image forming unit 500 is provided so that it can come into contact with the photoconductor 17 at the time of image formation, and the transfer from the photoconductor 17 to the first intermediate transfer belt 181 is performed by the four fan-shaped image forming units 500. A charging unit 10 is also provided to charge the photoconductor 17.

  The second intermediate transfer belt 182 is positioned so as to come into contact with the other end of the first intermediate transfer belt 181 that can come into contact with the photoreceptor. On the second intermediate transfer belt 182 having a circumferential length of about 500 mm, the respective visible images of the above-mentioned four colors of toner reaching the maximum A3 size are superimposed.

Next, the image forming process of this embodiment will be described in order.
In the state shown in FIG. 1, cyan image formation is in progress, and the visible image formed on the photoreceptor 17 is primarily transferred to the first intermediate transfer belt 181 and immediately from the other end to the second intermediate transfer belt. Transcribed. In other words, the primary transfer and the secondary transfer are performed substantially simultaneously. During this time, the other fan-shaped image forming units are retracted in the outer peripheral direction.

When the cyan image formation and the secondary transfer are completed, the revolver image forming device 50 including the photoconductor 17 and the four image forming units rotates 90 ° counterclockwise. In conjunction with this, the cyan image forming unit 500 (C) is retracted in the outer circumferential direction, and the first intermediate transfer belt 181 and the photoconductor 17 are separated. The magenta image forming unit 500 (M) is positioned at the position of the cyan image forming unit so far. In synchronization with the rotation of the revolver image forming device 50, the magenta image forming unit 500 (M) approaches the photoconductor 17, and the first intermediate transfer belt 181 and the photoconductor 17 come into contact with each other. Similar to cyan, a visible image of magenta is transferred onto the second intermediate belt 182.
In this way, all color toners are superimposed on the second intermediate belt 182. The process so far is imaged at the process speed V1.

On the other hand, the transfer paper is appropriately conveyed from the paper feed tray 1 and stands by in a state where the leading edge is gripped by the registration roller 20 in order to transfer the image. As described above, after images of all colors are superimposed on the second intermediate belt 182, the linear velocity of the second intermediate belt 182 is reduced from V1 to V2. The time-series reduction ratio from V1 to V2 is 2 or more. When the preparation is completed, the driving of the registration roller 20 is turned on, and the image is transferred at a speed V2 from here. That is, the third transfer to the transfer medium (transfer paper) is performed at V2.
Table 3 below summarizes the speed examples according to the present embodiment according to the grade of the image forming apparatus.

  In order to correspond to the process speed shown in Table 3 above, the writing unit 100 is particularly suitable for a medium speed machine or more when the multi-beam writing method is used. If the rotation speed of the polygon motor is also suitably assigned to each segment, the relationship between the light source / beam number of the optical writing unit and the rotation speed of the polygon motor is approximately as shown in Table 4 below.

  About this embodiment mentioned above, you may set suitably ratio of V1: V2 at 2 or more. Similarly to the conventional single layout, if black or mono color, V = V1 = V2 may be set as shown in Table 5 below.

  According to the first embodiment, each fan-shaped image forming unit is circumferentially arranged around the photosensitive member, and the primary transfer portion is performed in each fan-shaped image forming unit. It can be made compact, and transfer paper can be output at high speed while taking advantage of the features of the single layout.

Next, a radial type image forming apparatus as a second embodiment of the present invention will be described. FIG. 2 shows an outline of the configuration of the radial image forming apparatus 51 as the present embodiment.
In the second embodiment, the configuration and operation in the first embodiment described above are changed as follows.

(1) Transfer (secondary transfer) from the first intermediate transfer belt to the second intermediate belt is performed at four locations.
(2) Although it has a revolver configuration, each fan-shaped image forming unit does not rotate around the photoconductor 17, and the second intermediate transfer belt 182 wraps around the image forming engine so as to overlap each other via the first intermediate belt 181 of each color. This is a radial type image forming device that performs alignment.
(3) A belt contact / separation mechanism 503 is provided at the secondary transfer portion of each color in accordance with the configurations (1) and (2).
(4) The decharging / cleaning units were removed from the fan-shaped image forming units of each color, and were consolidated in the lower right part in FIG.
A writing unit for forming a latent image on an image carrier. Four developing units for forming a visible image on each image carrier. Four transfer units for transferring a visible image to a transfer medium (intermediate transfer belt).
・ Feeding unit that supplies media to be transferred to image forming device

Since the image forming procedure in this embodiment is the same as that in the first embodiment described above, a description thereof will be omitted.
According to the second embodiment, in addition to the effects obtained by the first embodiment described above, each fan-shaped image forming unit does not need to rotate as described in (2) as a merit of (1). Therefore, a drive system, a support mechanism coaxial with the photosensitive member, and the like can be omitted from the first embodiment described above. Further, as effect (4), further simplification, cost reduction, and compactness can be achieved.

Next, a symmetry type revolver type imaging apparatus as a third embodiment of the present invention will be described. FIG. 3 shows an outline of the configuration of the symmetry type revolver type image forming apparatus as the present embodiment.
In the third embodiment, the configuration and operation in the first embodiment described above are changed as follows.

(1) In order to simultaneously form images at two locations on the photoconductor 17, two sets of writing units and second intermediate transfer belts are provided.
(2) The two-color superimposed image is transferred to the transfer paper at the lower left in FIG. 3, and the remaining two-color superimposed image is further superimposed on the right in FIG.

The image forming process in this embodiment will be described in order.
In the state shown in FIG. 3, cyan and yellow images are being formed, and a visible image formed on the photosensitive member 17 is primarily transferred to each first intermediate transfer belt 181, and cyan is immediately transferred from the other end to the second intermediate state. Yellow is secondarily transferred onto the second intermediate transfer belt-2 (184) on the transfer belt-1 (183). During this time, the black and magenta fan-shaped image forming units are retracted in the outer circumferential direction.

  When the cyan and yellow image formation and the secondary transfer are completed, the revolver image forming apparatus 50 including the photoconductor 17 and the four image forming units rotates 90 ° counterclockwise. In conjunction with this, the cyan image forming unit 500 (C) and the yellow image forming unit 500 (Y) retract in the outer circumferential direction, and the first intermediate transfer belt 181 and the photoconductor 17 are separated from each other. The magenta image forming unit 500 (M) is positioned at the position of the cyan image forming unit so far, and the black image forming unit 500 (Bk) is positioned at the position of the yellow image forming unit so far. The magenta toner image is transferred onto the second intermediate belt-1 (183) and the black toner image is transferred onto the second intermediate belt-2 (184) in the same procedure as the previous two colors.

  In this way, all color toners are superimposed on the second intermediate belt. That is, the photosensitive member of the image forming unit 500 is retracted once every two cycles, and the revolver type image forming device 50 is rotated 180 ° (90 ° × 2) to perform full-color image formation of four colors.

  On the other hand, the transfer paper is appropriately conveyed from the paper feed tray 1 and waits with the leading end gripped by the registration roller 20 so as to transfer the image superimposed on the second intermediate belt as described above. As described above, after the images of all the colors are superimposed on the second intermediate belt, the registration roller 20 is driven, and from this, the two-color toner images of yellow and black are transferred to the second intermediate transfer belt-1 ( From 184), two-color toner images of cyan and magenta are sequentially transferred from the second intermediate transfer belt-2 (183) to the transfer paper.

According to the third embodiment, since a plurality of image forming units are arranged circumferentially around the image carrier (photosensitive member 17), the mechanism is simple, compact, lightweight, inexpensive, and A color imaging device that achieves both high productivity can be realized.
Further, although only one photoconductor is used, productivity (transfer paper output speed) twice that of a normal single layout configuration can be achieved.

Next, a photosensitive member moving type radial type image forming apparatus as a fourth embodiment of the present invention will be described. FIG. 4 shows an outline of the configuration of the radial type image forming apparatus as the present embodiment.
In the fourth embodiment, the configuration and operation in the second embodiment described above are changed as follows.

(1) The photosensitive member 17 is suspended and positioned inside the radial type image forming device 51, and most of the radial type image forming device 51 including the photosensitive member 17 and the writing unit 100 is vertically moved inside the second intermediate transfer belt. Swings left and right.
(2) The belt contact / separation mechanism is omitted, and a vacuum belt guide 504 is used to place the second intermediate transfer belt 182 in a concave shape around the image forming device, and the second intermediate transfer on the outer periphery of the radial image forming device 51. A plurality of locations outside the belt 182 are provided.

The image forming process in this embodiment will be described in order.
The state shown in FIG. 4 is during cyan image formation, where the radial type image forming device 51 is positioned downward (Y-axis (−) direction), and the first intermediate transfer belt 181 for cyan is the second intermediate transfer at the lower portion of the device. It is in contact with the belt 182. During this time, the other fan-shaped image forming units are retracted from the second intermediate transfer belt 182.

  When the cyan image formation and the secondary transfer are completed, the radial type image forming device 51 swings, retreats from the second intermediate transfer belt 182 at the lower portion of the cyan first intermediate transfer belt 181, and the magenta first intermediate transfer belt. 181 contacts the second intermediate transfer belt 182 at the lower left portion in FIG. Similar to cyan, a visible image of magenta is transferred onto the second intermediate belt 182. In this way, all color toners are superimposed on the second intermediate belt 182.

According to the present embodiment, in addition to the effects obtained by the second embodiment described above, the belt contacting / separating mechanism as in the second embodiment described above is omitted, so the number of parts is reduced and the mechanism is simplified. can do.
Further, since the path of the second intermediate transfer belt is fixed, stable secondary transfer can be performed and high image quality can be obtained.

Next, a double transfer type radial image forming apparatus as a fifth embodiment of the present invention will be described. FIG. 5 shows an outline of the configuration of the radial type image forming apparatus as the present embodiment.
In the fifth embodiment, the configuration and operation in the second and fourth embodiments described above are changed as follows.

(1) The photoconductor 17, the charging unit 10, the writing unit 100, and the cleaning / static discharge unit 502 swing vertically and horizontally.
(2) The second intermediate transfer belt is not provided, and each color is superimposed on the transfer paper.
(3) The transfer paper transport path passes through each color image forming unit, and a toner container 505 is installed in a space surrounded by the transfer paper transport path, and the toner transport pipe 506 transports the toner to the developing unit 501.
(4) The process speed V1 and the paper transport speed V2 are substantially the same.

The image forming process in this embodiment will be described in order.
In the state shown in FIG. 5, cyan image formation is in progress, and the photosensitive member 17 is positioned below (Y-axis (−) direction) and is in contact with the cyan intermediate transfer belt 18. During this time, the magenta / yellow / black intermediate transfer belt 18 is separated from the photoconductor 17.

  The cyan visible image formed on the photoconductor 17 is primarily transferred to the intermediate transfer belt 18, the driving of the registration roller 20 is turned on, and is secondarily transferred onto the transfer paper from the other end of the intermediate transfer belt 18. When the secondary transfer of cyan is completed, the photosensitive member 17 is swung, and the photosensitive member 17 is retracted from the cyan intermediate transfer belt 18 and the developing unit 501 and comes into contact with the first magenta intermediate transfer belt 181. Similar to cyan, a magenta image is also transferred to the transfer paper. In this way, all color toners are superimposed on the transfer paper and printed out after passing through the fixing unit.

  According to this embodiment, in addition to the effects obtained by the second and fourth embodiments described above, the second intermediate transfer belt can be omitted, and the image forming procedure is simplified because V1 and V2 are the same. Can do. Further, since the toner container is efficiently arranged, a compact image forming apparatus can be provided.

As described above, according to each of the above-described embodiments, transfer from the image carrier (photoconductor 17) to the transfer unit (intermediate transfer belt) is performed in at least two places. And a compact single layout color image forming device can be realized.
In addition, since the transfer from the transfer unit to the transfer medium (transfer paper) is performed in at least two places, a compact and highly productive single layout color image forming apparatus can be realized.

Further, the writing unit is an optical scanning device, and the light source of the optical scanning device is configured as a multi-beam system, so that the latent image formation by the writing unit can be speeded up, and the color imaging device with particularly high productivity. Can be realized.
In addition, it is preferable to increase the number of light sources of the optical scanning device to 4 or more in terms of speeding up.

を満足するため、シングルレイアウトでありながら高生産性を両立させるカラー作像装置が実現できる。 Further, a visible image is formed at the first image forming speed (V1) between the image carrier, the writing unit, the developing unit, and the transfer unit, and the visible image is transferred at the second image forming speed (V2). The visible image is transferred from the unit to the transfer medium, and the first image forming speed (V1) and the second image forming speed (V2) are

Therefore, it is possible to realize a color image forming apparatus that achieves both high productivity and single layout.

In addition, since at least two of the charging, cleaning, and charge eliminating units that are part of the electrophotographic process are integrated, a compact, lightweight, and inexpensive color image forming apparatus can be realized.
In addition, since the process cartridge is configured to integrally support at least one of the charging unit, the developing unit, and the cleaning unit and the image carrier and to be detachable from the image forming apparatus main body, the process cartridge is compact, lightweight, Excellent unit interchangeability can be realized with a color imaging device that is inexpensive, has high image quality and high productivity.

Note that the image forming apparatus in each of the above-described embodiments may be configured as an image forming apparatus by further including a transfer sheet storing / conveying unit as shown in FIG.
In addition, since the process cartridge in the image forming apparatus includes at least one of the photosensitive member and the associated unit together with the toner container, at least one of the photosensitive member and the associated unit can be replaced simultaneously with the toner. . Therefore, it is possible to save the user from exchanging those units and to improve convenience.

  Further, in each of the above-described embodiments, the description has been given of the configuration in which the transfer paper is discharged above the image forming apparatus mainly assuming a page printer. However, if the same effect can be obtained, the transfer paper is discharged. The direction may be a side or a downward direction. For this purpose, it is also effective to arrange the structure upside down or to lie at 90 degrees, and it is natural that they can be easily taken into account from the above-described embodiments.

In the above-described embodiments, the belt is used as the intermediate transfer unit. However, another intermediate transfer medium such as a drum may be used.
Further, although it has been described that toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk) are formed on the photoconductor 17, each of the three colors is formed as necessary. Alternatively, image formation using only two-color image forming units may be performed. It can be easily taken into consideration that the productivity in that case is 4/3 to 2 times that of four full colors. Alternatively, when the usage is close to the printing field, the apparatus configuration itself may be a quasi-color image forming apparatus (color image output apparatus) using three-color or two-color image forming units.

  Moreover, although it demonstrated as using an optical scanning device as a writing unit, it is good also as LED array type writing. According to this, it is possible to realize a color image forming apparatus with extremely high productivity and further promote simplification and miniaturization of the mechanism according to the present invention.

  Further, each of the above-described embodiments is a preferred embodiment of the present invention, and various modifications may be made, for example, by combining the technical elements of the embodiments within a consistent range without departing from the spirit of the present invention. It is possible to implement.

It is a figure which shows the outline | summary of a structure of the revolver type image forming apparatus as the 1st Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the radial type image forming apparatus 51 as the 2nd Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the symmetry type revolver type image forming apparatus as the 3rd Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the radial type image-forming apparatus of a photoreceptor movement type as the 4th Embodiment of this invention. It is a figure which shows the outline | summary of a structure of the radial type image-forming apparatus of a 2 times transfer type as the 5th Embodiment of this invention. It is a figure which shows an example of the image forming apparatus of the conventional single layout.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,801 Feed tray 2,802 Pressure roller 3,803 Fixing roller 804 2nd scanner 805 Revolver development 806 1st scanner 7,807 Writing mirror 8,808 Dust-proof glass 9,809 BTL lens 10,810 Charger 811 Lens 12, 812 f-θ lens-2
813 CCD base 14,814 f-θ lens-1
15, 815 Polygon mirror 16, 816 Drum cleaning unit 17, 817 Photoconductor 18, 818 Intermediate transfer belt 181 First intermediate transfer belt 182 Second intermediate transfer belt 183 Second intermediate transfer belt-1
184 Second intermediate transfer belt-2
819 Manual feed table 20, 820 Registration roller 21, 821 Intermediate roller 822 Bias roller 823 Paper transfer unit 824 Belt cleaning unit 825 Conveying belt 100 Optical scanning device (writing unit)
300 Image forming unit 501 Developing unit 502 Decharging / cleaning unit 503 Belt contact / separation mechanism 504 Vacuum belt guide 505 Toner container 506 Toner transport tube

Claims (10)

With only one image carrier,
At least one writing unit for forming a latent image on the image carrier;
At least two developing units for forming a visible image on the image carrier;
An image forming apparatus comprising: at least two transfer units that transfer the visible image to a transfer medium;
An image forming apparatus, wherein transfer from the image carrier to the transfer unit is performed in at least two places. The transfer unit comprises at least two first transfer units and at least one second transfer unit,
The image forming apparatus according to claim 1, wherein the transfer from the first transfer unit to the second transfer unit is performed in at least two places.   3. The image forming apparatus according to claim 1, wherein the writing unit is an optical scanning device, and a light source of the optical scanning device is configured as a multi-beam system.   The image forming apparatus according to claim 3, wherein the number of light sources of the optical scanning device is four or more.   The image forming apparatus according to claim 1, wherein the writing unit is configured as an LED array type. Controlled by the first image forming speed and the second image forming speed at the time of image forming on one transfer medium,
Between the image carrier, the writing unit, the developing unit, and the transfer unit, the visible image is formed at the first image forming speed, and the visible image is transferred at the second image forming speed. The visible image is transferred to a transfer medium,
The image forming apparatus according to any one of claims 1 to 5, wherein the first image forming speed (V1) and the second image forming speed (V2) satisfy the following expression (S1). apparatus.

However,
V1: First image forming speed V2: Second image forming speed Including at least two image forming units each including at least two developing units for forming a visible image on the image carrier and at least two transfer units for transferring the visible image to a transfer medium;
The image forming apparatus according to claim 1, wherein the image forming units are arranged circumferentially around the image carrier.   The image forming apparatus according to claim 1, wherein at least two of a charging unit, a cleaning unit, and a charge removing unit are provided outside the image forming unit. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus comprising: a transfer medium supply unit that supplies the transfer medium; and performing image formation.   The process cartridge according to claim 9, wherein at least one of a charging unit, a developing unit, and a cleaning unit and an image carrier are integrally supported, and the process cartridge is configured to be detachable from the main body of the image forming apparatus according to claim 9.

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