JP2003156896A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a belt and an image forming means from being soiled by toner. SOLUTION: In this image forming device, image forming stations Y, M, C and K where an electrifying means 19 and a developing means 20 are arranged around an image carrier 17 are provided along a transfer belt 14 for every color, and the transfer belt and the respective image forming stations are disposed in an oblique direction or a perpendicular direction, and an exposure means 6 forming a latent image on the image carrier is disposed under the image forming stations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an image forming station having a charging means and a developing means around an image carrier for each color along a transfer belt, and the transfer belt is passed through each station. The present invention relates to a tandem image forming apparatus that forms an image.

[0002]

2. Description of the Related Art The above-mentioned tandem type image forming apparatus is roughly classified and a plurality of image forming stations are arranged in a row.
The recording paper is electrostatically attracted to the conveyor belt, and the recording paper is sequentially brought into contact with each station while being conveyed, and electrostatic transfer force is applied between the station and the recording paper to record a toner image of a plurality of colors. A paper transport method that overlays colors while directly transferring to paper, and multiple image forming stations are arranged in rows.
While the intermediate transfer belt made of a dielectric material is brought into contact with each station and conveyed, the toner image formed at each station is sequentially primary-transferred by applying electrostatic transfer force between the station and the intermediate transfer belt. Then, two types of methods are employed: an intermediate transfer method in which colors are superposed on the intermediate transfer belt, and then secondary transfer is collectively performed from the intermediate transfer belt to the recording paper.

The above-mentioned paper transport system requires means (rollers and brushes) for attracting the recording paper to the transport belt and a high-voltage power supply, but the intermediate transfer system does not require these means and power supply. In the paper transport method, it is necessary to strictly control the transfer bias applied to each image transfer section according to the size, thickness, and type of recording paper, but in the intermediate transfer method, resistance is applied regardless of these factors of the recording paper. The primary transfer of the toner image is performed on the intermediate transfer belt having a constant thickness, surface roughness, and then the secondary transfer is collectively performed on the recording paper. It suffices to manage the transfer conditions as described above, and therefore the intermediate transfer method has many advantages.

On the other hand, when categorized by the arrangement method of each image forming station, there are a method of arranging each station horizontally and a method of arranging each station vertically.
The former has a drawback that the installation area is large, and the latter has a drawback that the height of the device is high and it is difficult to install it on a desk.

Therefore, conventionally, Japanese Patent Laid-Open No. 11-9552
No. 0 and Japanese Patent Laid-Open No. 8-305115, a method is known in which image forming stations are arranged in an oblique direction.

[0006]

However, in the above-mentioned conventional method, each image forming station is arranged above the belt surface which is obliquely arranged, whether it is the paper transport belt or the intermediate transfer belt. Therefore, the toner spills from the developing means in the image forming station and stains the belt and other image forming means, resulting in deterioration of image quality. In addition, since the exposure means has to be arranged above the apparatus main body, the vibration of the frame supporting the exposure means increases due to the polygon motor rotating at a high speed and the drive system for driving the image forming means, which causes deterioration in image quality. have.

The present invention is to solve the above-mentioned conventional problems, and to prevent toner stains on the belt and the image forming means in the image forming apparatus in which the image forming stations are arranged diagonally or vertically. It is an object of the present invention to provide an image forming apparatus capable of reducing the vibration of the exposure unit.

[0008]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention has an image forming station in which a charging means and a developing means are arranged around an image carrier and a transfer belt. In the image forming apparatus in which the transfer belt and the image forming stations are arranged in a diagonal direction or in a vertical direction, the exposing means for forming a latent image on the image carrier is provided in each of the image forming stations. The invention according to claim 2 is characterized in that the transfer belt is an intermediate transfer belt, and the invention according to claim 3 is characterized in that The transfer belt is a paper transport belt, and the invention according to claim 4 is the space on the side opposite to the image forming station with respect to the transfer belt. The invention according to claim 5 is characterized in that fixing means is provided, and in the invention according to claim 1, a control unit and a power supply unit are provided adjacently above the exposure means, and the exposure means, the control unit, and Cooling air is blown between the power supply unit and the power supply unit. According to the invention of claim 6, the exposure means comprises a case, and a single scanner means is arranged at the bottom of the case. According to a seventh aspect of the present invention, the image is obtained by bending the single scanner means, the f-θ lens and the reflection mirror, and the scanning optical path of each color reflected by the reflection mirror. It is characterized in that a folding mirror for irradiating the carrier is arranged.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show one embodiment of the image forming apparatus of the present invention, FIG. 1 is a schematic sectional view showing the entire structure, FIG. 2 is an enlarged view of the transfer belt and the image forming unit of FIG. 1, and FIG. Is an enlarged view of the exposure means of FIG.
FIG. 4 is an assembly perspective view of the transfer belt and the image carrier.
In addition, about the same structure between each drawing, the same number may be attached | subjected and description may be abbreviate | omitted. The present embodiment is an example of the above-mentioned intermediate transfer method.

In FIG. 1, an image forming apparatus 1 according to the present embodiment includes a housing 2, a paper discharge tray 2a formed on the upper portion of the housing 2, and a door body 3 mounted on the front surface of the housing 2 so as to be openable and closable. The housing 2 includes a control unit 4, a power supply unit 5, and an exposure unit (exposure means).
6, an image forming unit 7, a cooling unit 8 including a blower fan, a transfer belt unit 9, and a paper feeding unit 10 are arranged, and a paper conveying unit 11 is arranged in the door body 3. Each unit is configured to be attachable to and detachable from the main body, and is configured such that it can be integrally removed for repair or replacement during maintenance or the like.

The transfer belt unit 9 includes a drive roller 12 disposed below the housing 2 and rotated by a drive source (not shown), and a driven roller 13 disposed obliquely above the drive roller 12. The intermediate transfer belt 14 which is stretched between the rollers and is driven to circulate in the direction of the arrow (counterclockwise) in the drawing, and the cleaning unit 15 which contacts the surface of the intermediate transfer belt 14, and the driven roller 13 and the intermediate transfer belt. 14 is disposed in a direction inclined to the left side in the drawing with respect to the drive roller 12. As a result, when the intermediate transfer belt 14 is driven, the belt surface 14a in which the belt conveying direction X faces downward is located below, and the belt surface 14b in which the conveying direction faces upward is located above. In the present embodiment, the belt surface 14a is a belt tension surface (a surface pulled by the driving roller 12) when the belt is driven, and the belt surface 14b is a belt slack surface when the belt is driven.

The drive roller 12 also serves as a backup roller for a secondary transfer roller 39 described later. As shown in FIG. 2, the peripheral surface of the driving roller 12 has a thickness of about 3 mm,
A rubber layer 12a having a volume resistivity of 10 ⁵ Ω · cm or less is formed, and by being grounded via a metal shaft,
It is used as a conductive path of the secondary transfer bias supplied through the secondary transfer roller 39. By thus providing the driving roller 12 with the rubber layer 12a having high friction and shock absorption, it is difficult for the shock when the recording medium enters the secondary transfer portion to be transmitted to the intermediate transfer belt 14, resulting in deterioration of image quality. Can be prevented.

Further, in this embodiment, the diameter of the driving roller 12 is smaller than the diameter of the driven roller 13. As a result, the recording paper after the secondary transfer can be easily separated by the elastic force of the recording paper itself. Further, the driven roller 13 is also used as a backup roller of the cleaning means 15 described later.

The cleaning means 15 is provided on the belt surface 14a side facing downward in the transport direction. As shown in FIG. 2, a cleaning blade 15a for removing the toner remaining on the surface of the intermediate transfer belt 14 after the secondary transfer,
The cleaning blade 15a is provided with a toner conveying member 15b for conveying the collected toner, and the cleaning blade 15a is in contact with the intermediate transfer belt 14 at a portion where the intermediate transfer belt 14 is wound around the driven roller 13.

Further, on the back surface of the intermediate transfer belt 14, a primary transfer member 16 composed of a leaf spring electrode is provided so as to face an image carrier 17 of each of image forming stations Y, M, C and K described later.
Is abutted by its elastic force, and a transfer bias is applied to the primary transfer member 16.

The image forming unit 7 includes image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (black) for forming a plurality of (four in this embodiment) images of different colors. 2), as shown in detail in FIG. 2, each of the image forming stations Y, M, C, and K has an image carrier 17 composed of a photosensitive drum and an image carrier 1 respectively.
7 is provided with a charging unit 19 and a developing unit 20 which are arranged around the periphery 7 and are composed of a corona charging unit. The image forming stations Y, M, C, K may be arranged in any order.

The image forming stations Y, M,
The C and K image carriers 17 are brought into contact with the belt surface 14a of the intermediate transfer belt 14 which faces downward in the conveying direction, and as a result, the respective image forming stations Y, M, C and K are also moved relative to the drive roller 12. It is arranged in a direction inclined to the left side in the figure. The image carrier 17, as shown by the arrow in the figure,
The intermediate transfer belt 14 is rotationally driven in the conveying direction. The intermediate transfer belt 14 may be arranged in a direction inclined to the right side in the figure with respect to the drive roller 12. In that case,
The belt conveying direction X is the opposite direction, and the belt surface facing downward in the conveying direction is 14b.

Next, the charging means 19 will be described in detail by taking the image forming station C of FIG. 2 as an example. The developing means 20 includes a developing roller exposing portion 20 near the developing roller 33.
a is formed, on the other hand, the corona charging means 19 which is a charging means is provided with an opening 1 facing upward facing the image carrier 17.
9a is formed. At this time, the developing roller exposing portion 2
0a below the corona charging means 19 upward opening 19a
When the position is positioned, toner spills from the developing roller exposed portion 20a due to gravity, enters the corona charging means 19 through the upward opening 19a of the corona charging means 19, and stains the corona charging means 19.

Therefore, in the present embodiment, the upward opening 19a is provided on the intermediate transfer belt 14 side so that the upward opening 19a of the corona charging device 19 does not overlap the developing roller exposed portion 20a of the developing device 20. I am trying to offset it. As a result, the developing roller exposing portion 2
It is possible to solve the problem that the toner spills from 0a due to gravity, enters the corona charging means 19 through the upward opening 19a, and stains the corona charging means 19.

The exposing means 6 is arranged in a space formed obliquely below the image forming unit 7 arranged obliquely, and the control unit 4 and the power supply unit 5 are arranged in the space above the exposing means 6. Has been done. Further, a paper feeding unit 10 is arranged at the bottom of the housing 2 below the exposure means 6. Since the control unit 4 and the power supply unit 5 are arranged adjacent to the exposure unit 6, a frame for supporting the device parts laterally of the image forming unit 7 and the intermediate transfer belt 14 (the depth direction of the paper surface of FIG. 1). The installation space can be made smaller than when these are arranged in parallel with.

As shown in FIGS. 1 and 3, the exposure means 6
Has a case 18. The case 18 is disposed in a space formed obliquely below the belt surface 14a facing downward in the transport direction, and the inclined surface 18a of the case 18 is parallel to the belt surface 14a. At the bottom of the case 18, a single scanner means 21 including a polygon mirror motor 21a and a polygon mirror 21b is arranged, a single f-θ lens 22 and a reflection mirror 23 are arranged, and further, reflection is performed. Above the mirror 23, the scanning optical paths y, m, c, k of the respective colors are provided.
So as to be parallel to the inclined surface 18a (belt surface 14a), the four folding mirrors 2 are arranged in the scanning optical paths y, m, c, k.
4 is provided, and three folding mirrors 25 are arranged in the scanning optical paths m, c, k so that the scanning optical paths y, m, c, k reflected by the folding mirror 24 are irradiated to the image carrier 17. I have set up.

By providing the folding mirrors 24 and 25 in this way, the scanning optical paths y, m, c and k can be bent, and the height of the case 18 can be reduced, thereby achieving a compact size. In addition, each image forming station Y,
The folding mirrors 24 and 25 are arranged so that the scanning optical path lengths of the M, C, and K to the image carrier 17 are the same.

In the exposure means 6 having the above structure,
The image signal corresponding to each color from the polygon mirror 21b
The light is modulated and formed based on a common data clock frequency, and is emitted, and then passes through the f-θ lens 22, the reflection mirror 23, and the folding mirrors 24 and 25 to the image carrier 17 of each image forming station Y, M, C, K. It is illuminated and a latent image is formed.

In this embodiment, by arranging the scanning optical system below the apparatus, the vibration of the scanning optical system due to the vibration given to the frame supporting the apparatus by the drive system of the image forming means can be minimized. It is possible to prevent deterioration of image quality. In particular, the scanner means 21 is installed in the case 1
By arranging at the bottom of 8, the polygon motor 21a
The vibration applied to the entire case 18 by itself can be minimized, and the deterioration of the image quality can be prevented. Also,
By making the number of the polygon motors 21a that are the vibration sources one, it is possible to minimize the vibration applied to the entire case 18.

On the side surface of the housing 2, a cooling means 8 composed of a blower fan is provided, and external air is introduced in the direction of the arrow shown in the drawing to cool the exposure means 6, the control unit 4 and the power supply unit 5. After the air taken into the apparatus from the rear of the recording paper P conveyance direction or the width direction of the recording paper P conveyance direction is guided to the vicinity of the polygon motor 21a, and further to the control unit 4 and the power supply unit 5,
Since the cooling passage leading to the outside of the apparatus is formed, the temperature rise of the polygon motor 21a is suppressed, the deterioration of the image quality is prevented, and the life of the polygon motor 21a is extended.

Next, the details of the developing means 20 will be described with reference to FIG.
The image forming station Y will be described as a representative. In the present embodiment, the image stations Y, M, C, and K are arranged in an oblique direction, and the image carrier 17 is in contact with the belt surface 14a of the intermediate transfer belt 14 facing downward in the transport direction. The toner storage container 26 is arranged obliquely downward. Therefore, the developing unit 20 has a special configuration.

That is, the developing means 20 includes a toner storage container 26 for storing toner (hatched portion in the drawing), and a toner storage portion 27 formed in the toner storage container 26.
And the toner stirring member 2 disposed in the toner storage unit 27.
9, a partition member 30 formed in the upper part of the toner storage portion 27, a toner supply roller 31 disposed above the partition member 30, and a toner supply roller 31 provided on the partition member 30 and abutting against the toner supply roller 31. The flexible blade 32 includes a developing roller 33 arranged to come into contact with the toner supply roller 31 and the image carrier 17, and a regulation blade 34 brought into contact with the developing roller 33.

The image carrier 17 is rotated in the conveying direction of the intermediate transfer belt 14, and the developing roller 33 and the supply roller 31 are rotated.
Is rotationally driven in the direction opposite to the rotational direction of the image carrier 17, while the stirring member 29 is rotationally driven in the direction opposite to the rotational direction of the supply roller 31. The toner stirred and carried up by the stirring member 29 in the toner storage unit 27 is supplied to the toner supply roller 31 along the upper surface of the partition member 30, and the supplied toner is rubbed against the flexible blade 32 and supplied. It is supplied to the surface of the developing roller 33 by the mechanical adhesive force to the uneven surface portion of the roller 31 and the adhesive force due to the electric power of friction. The toner supplied to the developing roller 33 is regulated by the regulating blade 34 into a coating layer having a predetermined thickness, and the thinned toner layer is conveyed to the image carrier 17 and is developed by the developing roller 33 and the image carrier 17.
The image carrier 1 at and around the nip portion formed by the contact
The latent image portion 7 is developed.

In the present embodiment, the developing roller 33, the toner supply roller 31, and the contact portion between the developing roller 33 and the regulating blade 34 on the side facing the image carrier 17 are not buried in the toner in the toner storage portion 27. I am trying. With this configuration, it is possible to prevent fluctuation of the contact pressure of the regulation blade 34 with respect to the developing roller 33 due to the reduction of the stored toner, and the excess toner scraped off from the developing roller 33 by the regulation blade 34 falls into the toner storage portion 27. Therefore, the filming of the developing roller 33 can be prevented.

The contact portion between the developing roller 33 and the regulating blade 34 is located below the contact position between the supply roller 31 and the developing roller 33, and the supply roller 31 causes the developing roller 3 to move.
3 is provided to the toner storage portion 27 below the developing means, and the excess toner that has not been transferred to the developing roller 33 and the excess toner that has been regulated and removed from the developing roller 33 by the regulation blade 34 is provided. The toner returned to is agitated with the toner in the toner storage portion 27 by the agitating member 29, and is again supplied to the toner introducing portion near the supply roller 31 by the agitating member 29. Therefore, the surplus toner is dropped to the lower portion without being jammed in the rubbing portion between the supply roller 31 and the developing roller 33 or the contact portion between the developing roller 33 and the regulating blade 34 to stir the toner in the toner storage portion 27. It is possible to prevent the deterioration of the toner in the developing means from gradually progressing and to cause a sudden change in image quality immediately after the replacement of the developing means.

Returning to FIG. 1, the paper feeding unit 10 is provided with a paper feeding cassette 35 in which recording media P are stacked and held, and a pickup roller 36 for feeding the recording media P one by one from the paper feeding cassette 35. There is.

The paper transport unit 11 includes a pair of gate rollers 3 for defining the timing of feeding the recording medium P to the secondary transfer portion.
7 (one roller is provided on the housing 2 side)
A secondary transfer roller 39 as a secondary transfer unit that is pressed against the drive roller 12 and the intermediate transfer belt 14, a main recording medium conveyance path 38, a fixing unit 40, and a discharge roller pair 4
1 and double-sided printing conveyance path 42.

The fixing means 40 has a heating element such as a halogen heater built in at least one of them, and the fixing roller pair 4 is rotatable.
0a and pressing means for pressing at least one roller of the fixing roller pair 40a to the other side to press the secondary image secondarily transferred to the sheet material onto the recording medium P. The secondary image secondarily transferred to the fixing roller pair 40a
The toner is fixed on the recording medium at a predetermined temperature in the nip portion formed by. In the present embodiment, the fixing unit 40 is arranged in a space formed diagonally above the belt surface 14b that is upward in the conveying direction of the transfer belt, in other words, in a space on the opposite side of the transfer belt from the image forming station. This makes it possible to reduce heat transfer to the exposure unit 6, the intermediate transfer belt 14, and the image forming unit, and to reduce the frequency of color misregistration correction operation for each color. In particular, the exposure unit 6 is located at the farthest position from the fixing unit 40, and the displacement of the scanning optical system component due to heat can be minimized, and the color shift can be prevented.

FIG. 4 shows the intermediate transfer belt 14, the cleaning means 15, the primary transfer member 16, and the image carriers 17 of the image forming stations Y, M, C, and K described in FIG. The drive roller 12 and the driven roller 13 shown in FIG. 1 are attached to the pair of left and right frames 50, and the intermediate transfer belt 1 is interposed between the drive roller 12 and the driven roller 13.
4 is stretched. A belt drive gear 51 is connected to one end of the drive roller 12, and each image carrier 17
An image carrier drive gear 52 is connected to one end of the drive gear 52, and a relay gear 53 is meshed between the drive gears 52. A drive motor 54 is disposed on the most upstream side in the belt conveyance direction X, and a transmission gear 55 is meshed between the rotation shaft 54a of the drive motor 54 and the drive gear 52 of the most upstream image carrier 17. There is. Incidentally, reference numeral 56 denotes a toner recovery container arranged on the side surface of the frame 50 so as to collect the waste toner from the cleaning means 15.

In the above structure, the image carrier 17 for each color
Are commonly supported by a pair of frames (not shown), and a transmission gear 54 arranged in one row from one drive motor 54 disposed above the intermediate transfer belt 14 and an image carrier drive gear 5
2. The image carrier 17 is sequentially driven by the relay gear 53, and the drive roller 12 of the intermediate transfer belt 14 is driven by the image carrier drive gear 52 at the lowest stage via the belt drive gear 51. There is. Also, the relay gear 53
And the number of teeth of the belt drive gear 51 are the same, the rotation cycle unevenness is matched, and the interval of one rotation of the drive roller 12 and the primary transfer portion of each color image forming means are substantially the same. This allows
It is possible to match the rotational phase of each image carrier 17 and gear at the manufacturing stage, and even if the image carrier 17 is replaced, the color shift due to the uneven rotation of the image carrier 17 can be minimized. it can.

Further, since there is a rotational load on the intermediate transfer belt 14 due to the cleaning means 15, the backlash existing at the meshing parts of the gears is always in one direction, so that the color shift due to the backlash can be prevented. it can.

In the present embodiment, the intermediate transfer belt 1
Since 4 is arranged in the direction inclined with respect to the drive roller 12, a wide space is created in the right space in the drawing, and the fixing means 40 can be arranged in that space, and downsizing can be realized. At the same time, the heat generated by the fixing unit 40 is exposed to the left side of the exposure unit 6 and the intermediate transfer belt 1.
4 and each image forming station Y, M, C, K can be prevented from being transmitted. Further, since the exposure unit 6 can be arranged in the space on the lower left side of the image forming unit 7, the drive system of the image forming unit is the housing 2.
The vibration of the scanning optical system of the exposure unit 6 due to the vibration given to can be suppressed to the minimum, and the deterioration of the image quality can be prevented.

Further, in the present embodiment, the primary transfer efficiency is increased (approximately 100%) by using the spherical toner, and the cleaning for recovering the residual toner after the primary transfer is performed on each image carrier 17. No means are set up. As a result, it is possible to arrange the image bearing members 17 each including a photosensitive drum having a diameter of 30 mm or less in close proximity to each other, and the device can be downsized.

Since the cleaning means is not installed, the corona charging means 19 is used as the charging means. When the charging means is a roller, a small amount of the primary transfer residual toner existing on the image carrier 17 is accumulated on the roller to cause charging failure, but the corona charging means 19 which is a non-contact charging means. The toner is less likely to adhere to the toner, and the occurrence of poor charging can be prevented.

The outline of the operation of the entire image forming apparatus as described above is as follows. (1) When a print command signal (image forming signal) from a host computer or the like (not shown) (personal computer or the like) is input to the control unit 4 of the image forming apparatus 1, each of the image forming stations Y, M, C, and K. The image carrier 17, each roller of the developing device 20, and the intermediate transfer belt 14 are rotationally driven. (2) The outer peripheral surface of the image carrier 17 is uniformly charged by the charging means 19. (3) The exposure unit 6 selectively exposes the outer peripheral surface of the image carrier 17 uniformly charged in each of the image forming stations Y, M, C, and K in accordance with the image information of each color. An electrostatic latent image is formed. (4) The toner images of the electrostatic latent images formed on the respective image carriers 17 are developed by the developing means 20. (5) A primary transfer voltage having a polarity opposite to the charging polarity of toner is applied to the primary transfer member 16 of the intermediate transfer belt 14, and the toner image formed on the image carrier 17 is transferred to the intermediate transfer belt at the primary transfer portion. Along with the movement of 14, the images are sequentially transferred and superposed on the intermediate transfer belt 14. (7) Intermediate transfer belt 14 to which this primary image is primarily transferred
The recording medium P stored in the paper feeding cassette 35 is fed to the secondary transfer roller 39 via the pair of registration rollers 37 in synchronization with the movement of the sheet. (8) The primary transfer image is synchronously merged with the recording medium at the secondary transfer portion, and the primary transfer image is generated by the secondary transfer roller 39 pressed toward the drive roller 12 of the intermediate transfer belt 14 by a pressing mechanism (not shown). A bias having a polarity opposite to that of the transfer image is applied, and the primary transfer image formed on the intermediate transfer belt 14 is secondarily transferred to the recording medium that is synchronously fed. (9) The untransferred toner in the secondary transfer is conveyed toward the driven roller 13 and is scraped off by the cleaning means 15 arranged facing the roller 13, and the intermediate transfer belt 14 is refreshed. Then, the above cycle can be repeated again. (10) The toner image on the recording medium is fixed by passing the recording medium through the fixing means 40, and then the recording medium is directed to a predetermined position (when it is not double-sided printing, it is directed to the discharge tray 2a and double-sided printing). In the case of (2), it is conveyed toward the double-sided printing conveyance path 42).

FIG. 5 is a schematic sectional view showing the overall construction of another embodiment of the image forming apparatus of the present invention. In addition,
The same components as those in the embodiment of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The present embodiment is an example of the above-described paper conveyance system, and uses the paper conveyance belt 43 instead of the intermediate transfer belt 14 in FIG.

In this embodiment, the transfer unit 9 and the paper transport unit 11 are provided in the door body 3. The transfer unit 9 is provided above the housing 2, and is driven by a drive source (not shown) to rotate. The driven roller 13 and the backup roller 44 are provided obliquely below the drive roller 12. A paper conveying belt 43 which is stretched around a book roller and is circularly driven in a direction indicated by an arrow (clockwise direction), and a cleaning unit 1 which faces the backup roller 44 and contacts the surface of the paper conveying belt 43.
5, the drive roller 12 and the paper transport belt 43 are arranged in a direction inclined to the left side in the figure with respect to the driven roller 13. As a result, the belt tension side (side pulled by the drive roller 12) 43 when the paper transport belt 43 is driven
a is located below, and the belt slack side 43b is located above.

On the back surface of the paper transport belt 43, a transfer member 45 composed of a leaf spring electrode is brought into contact with the image carrier 17 of each of the image forming stations Y, M, C and K by its elastic force. A transfer bias is applied to the transfer member 45. Then, the image forming stations Y, M, C, K
The image bearing member 17 of the paper conveyance belt 43 is on the belt tension side 43 of the paper conveyance belt 43.
As a result, the image forming stations Y, M, C, and K are also arranged in a direction inclined to the left side with respect to the driven roller 13 in the drawing.

FIG. 6 is a schematic sectional view showing the overall construction of another embodiment of the image forming apparatus of the present invention. In addition,
The same components as those in the embodiment of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the intermediate transfer belt 14
The image forming stations Y, M, C, and K are arranged in the vertical direction. Other configurations and operational effects are similar to those of the embodiment shown in FIG. 1, and therefore description thereof will be omitted.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and a conventionally known or well-known technique can be replaced or added as necessary.

For example, in the embodiment shown in FIGS. 1 and 6, the driving roller 12 is arranged below and the driven roller 13 is arranged above, but the driven roller 13 is arranged below.
You may make it arrange | position 3 upward.

In the present invention, the intermediate transfer belt and the paper transport belt are generically defined as a transfer belt.

[0048]

As is apparent from the above description, according to the present invention, it is possible to prevent toner stains on the belt and the image forming means in the image forming apparatus in which the image forming stations are arranged obliquely or vertically. In addition, the vibration of the exposure unit can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the transfer belt and the image forming unit of FIG.

FIG. 3 is an enlarged view of the exposure unit of FIG.

4 is an assembled perspective view of the transfer belt and the image carrier of FIG.

FIG. 5 is a schematic cross-sectional view showing another embodiment of the image forming apparatus of the present invention and showing the overall configuration.

FIG. 6 is a schematic cross-sectional view showing another embodiment of the image forming apparatus of the invention and showing the overall configuration.

[Explanation of symbols]

13 ... driven roller 14 ... Intermediate transfer belt (transfer belt) 17 ... Image bearing member 18 ... Case 19 ... Charging means 20 ... Developing means 21 ... Scanner means 22 ... f-θ lens 23 ... Reflective mirror 24, 25 ... Folding mirror 40 ... Fixing means 43 ... Paper transport belt (transfer belt)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/16 103 G03G 15/20 2H076 15/20 21/00 534 2H200 21/20 B41J 3/00 D ( 72) Inventor Yujiro Nomura 3-5 Yamato 3-chome, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2C362 BA51 BA90 CB80 DA04 DA19 DA32 DA34 EA00 2H027 JA11 JB11 JB16 JC05 JC16 JC18 2H030 AABB A02BB21 AB02 AB02 BB43 2H033 AA21 AA41 BA02 BA29 2H071 DA02 DA03 DA05 DA12 DA15 DA31 DA34 EA04 EA18 2H076 AB06 AB12 AB18 EA04 EA14 2H200 FA17 GA12 GA23 GA34 GA44 GA47 GB25 GB41 HA02 HA12 HA28 HB03 HB12 HB22 HB12 HB26 J10 JA02 J02

Claims (7)

[Claims] 1. An image forming station, in which a charging unit and a developing unit are arranged around an image carrier, is provided for each color along a transfer belt, and the transfer belt and each image forming station are arranged obliquely or vertically. In the image forming apparatus described above, an exposing unit that forms a latent image on the image carrier is disposed below each of the image forming stations. 2. The image forming apparatus according to claim 1, wherein the transfer belt is an intermediate transfer belt. 3. The image forming apparatus according to claim 1, wherein the transfer belt is a paper transport belt. 4. The image forming apparatus according to claim 1, wherein a fixing unit is arranged in a space opposite to the image forming station with respect to the transfer belt. 5. A control unit and a power supply unit are disposed adjacent to and above the exposure means, and cooling air is blown between the exposure means and the control unit and power supply unit. 1. The image forming apparatus according to 1. 6. The image forming apparatus according to claim 1, wherein the exposing means comprises a case, and a single scanner means is provided at the bottom of the case. 7. A single scanner means, an f-θ lens and a reflecting mirror, and a folding mirror for bending the scanning optical path of each color reflected by the reflecting mirror to irradiate the image carrier are provided. The image forming apparatus according to claim 6.