JP2003159835A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an image having a high image quality by reducing heating at the bearing part of a rotary polyhedral mirror, thereby suppressing temperature variation in an exposing unit. <P>SOLUTION: The imaging apparatus comprises a plurality of means for forming a latent image on image carriers arranged in parallel and developing the latent image by a developing means, and means 6 for exposing each image carrier with a laser beam to form a latent image. The exposing means 6 comprises a plurality of laser light sources being modulated by image data in correspondence with the plurality of image carriers 17, a common rotary polyhedral mirror 21 disposed horizontally and performing deflection scanning by reflecting the laser beam from each laser light source on a common reflection plane, and an optical path through which the laser beam performs deflection scanning not in parallel with each image carrier 17. The imaging apparatus further comprises means for transferring and recording developed toner images of respective image carriers 17 while superposing, and means 40 for fixing the recorded tone image located at a position separated from the exposing means 6. <P>COPYRIGHT: (C)2003,JPO

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 divided into a plurality of image forming stations arranged in a row, and the recording paper is electrostatically adsorbed on a conveyor belt to sequentially transfer the recording paper to each station. A paper conveyance method in which electrostatic transfer force is applied between the station and the recording paper while abutting and conveying them to directly superimpose toner images of a plurality of colors on the recording paper to superpose colors, and each image forming station. A plurality of columns are arranged in a line and the intermediate transfer belt made of a dielectric is brought into contact with each station and conveyed, while the toner image formed at each station is electrostatically transferred between the station and the intermediate transfer belt. Two types of methods are adopted: an intermediate transfer method in which a force is applied to sequentially perform primary transfer, color superimposition is performed on the intermediate transfer belt, and then secondary transfer is performed collectively from the intermediate transfer belt to recording paper. The .

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. The former is provided with an exposure device corresponding to each image forming station, and the latter is provided with an exposure device commonly to each image forming station.

[0006]

However, in the above-mentioned conventional system, each of the image forming stations is arranged above the belt surface arranged in the oblique system regardless of 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, there is a problem that the vibration of the apparatus main body becomes large and the image quality deteriorates.

In an apparatus having an exposure device common to each image forming station, since the scanning lines can be radially emitted from the exposure device, there is an advantage that the exposure device can be downsized, but the exposure device and a plurality of image carriers are provided. When the fixed frame expands due to temperature fluctuations and the relative position between the exposure device and the image forming station changes, the laser beams are not parallel and the pitch of the scanning lines also changes according to the relative angle between the scanning lines. Occurs. Fluctuations in the scanning line pitch result in fluctuations in the scanning position on the image carrier, which causes the image position to shift depending on the color, resulting in color shift, which greatly deteriorates image quality. Therefore, when the laser beam is non-parallel type,
It is important to prevent temperature fluctuations inside the apparatus to prevent fluctuations in the relative position between the exposure apparatus and the image forming station.

In particular, in recent years, with the increase in speed and resolution of image forming apparatuses, the number of rotations of the rotary polygon mirror tends to reach an area of tens of thousands RPM, and the load increases on the rotary polygon mirror bearing. It is getting bigger. However, when the rotary polygon mirror is obliquely arranged as in the conventional device, a radial force acts only in the gravity direction of the bearing portion, and friction increases at that portion, so that the drive motor, the bearing, etc. Heat generation in the vicinity of them also becomes large. Such heat generation naturally increases the temperature variation of the entire apparatus, which is also a cause of image deterioration due to the color shift.

[0009]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art, and in particular, even when performing deflection scanning with a non-parallel laser beam with a common rotary polygon mirror,
The heat generation of the bearing portion of the rotary polygon mirror is reduced, the temperature fluctuation in the exposure apparatus is reduced, and high quality image formation is enabled.

Therefore, according to the present invention, a plurality of image forming means arranged in parallel to form a latent image on the image bearing member and developing the latent image formed by the developing means, and a laser beam on each of the image bearing members. In an image forming apparatus provided with an exposing unit that exposes to form a latent image, the exposing unit includes a plurality of laser light sources that are modulated by image data corresponding to the plurality of image carriers, and is horizontally arranged. A common rotary polygon mirror for deflecting and scanning the laser beam of each laser light source on a common reflecting surface, and an optical path for deflecting and scanning the laser beam non-parallel to each image carrier. And a recording means for transferring and recording the developed toner images of the respective image carriers in an overlapping manner, and a fixing means for fixing the recorded toner images, wherein the fixing means is located at a position apart from the exposing means. Placed in It is characterized in.

In the rotary polygon mirror, the bearing portion is fitted in the case of the exposing means to expose a part thereof to the outside of the case,
The optical path is provided with a plurality of mirrors for radially deflecting and scanning while the laser beam is reflected back from the common reflecting surface of the rotary polygon mirror, and from the common reflecting surface of the rotary polygon mirror to each of the image carriers. The lengths are substantially the same, and the plurality of laser light sources are arranged at positions where the respective laser beams are radially reflected by a common reflection surface of the rotary polygon mirror.

Further, the present invention is characterized in that the laser beams of the plurality of laser light sources are reflected at a common position on the common reflecting surface and deflected and scanned.

The plurality of image carriers are arranged in parallel upward along an oblique arch line, the exposing means is arranged obliquely below the plurality of image carrier arrangements, and the fixing means is It is arranged diagonally above the plurality of image carriers on the side opposite to the exposing means, or the recording means is flexible so as to be pressed against and follow each of the image carriers along the oblique arch line. An endless intermediate transfer medium, a paper transport path for transporting the recording paper, and a transfer means for transferring the toner image from the intermediate transfer medium onto the recording paper on the paper transport path,
The fixing means is arranged on the paper conveying path, the rotary polygon mirror is arranged below one side surface, and the fixing means is arranged above the other side surface.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an overall configuration showing an embodiment of an image forming apparatus according to the present invention. 1 is an image forming apparatus, 2 is a housing, 3 is a door, and 6
Is an exposure unit, 7 is an image forming unit, 8 is a cooling unit, 9 is a transfer belt unit, 10 is a paper feeding unit, 1
1 is a paper transport unit, 15 is a cleaning unit, 17 is an image carrier, 18 is an intermediate transfer belt, 20 is a developing unit, 2
Reference numeral 1 is a scanner means, 21b is a rotary polygon mirror, and 40 is a fixing means.

In FIG. 1, an image forming apparatus 1 of this embodiment includes a housing 2, a paper discharge tray 2a formed on the upper portion of the housing 2, and a door body 3 which is mounted on the front surface of the housing 2 so as to be openable and closable. The housing 2 is provided with an exposure unit (exposure means) 6, an image forming unit 7, a cooling means 8 including a blower fan, a transfer belt unit 9, and a paper feeding unit 10, and inside the door body 3. Paper transport unit 1
1 is provided. 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 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. Equipped). In each of the image forming stations Y, M, C, and K, an image carrier 17 made of a photosensitive drum, a charging unit 19 made of corona charging unit disposed around the image carrier 17, and a developing unit are provided. Each image forming station Y,
M, C, and K are arranged in parallel on the lower side of the transfer belt unit 9 so that the image carrier 17 faces upward along an oblique arch line. The image forming stations Y, M, C, K may be arranged in any order.

The transfer belt unit 9 is provided below the housing 2 and is driven by a drive source (not shown) to rotate, a driven roller 13 disposed obliquely above the drive roller 12, and a backup roller. (Tension roller) 14, intermediate transfer belt 18 which is stretched between these three rollers and is driven to circulate in the direction of the arrow (counterclockwise X), and cleaning means 15 which comes into contact with the surface of intermediate transfer belt 18. It has and. Driven roller 1
3, backup roller 14 and intermediate transfer belt 18
Is disposed in a direction inclined to the left side in the drawing with respect to the drive roller 12, and as a result, the belt surface 18a on which the belt transfer direction X when the intermediate transfer belt 18 is driven is directed downward is positioned below and the transfer direction is directed upward. The belt surface 18b that becomes is located above.

Therefore, each image forming station Y,
M, C, and K are also arranged in the direction inclined to the left side in the figure with respect to the drive roller 12. The image carrier 17
Is pressed against the belt surface 18a of the intermediate transfer belt 18 which is downward in the conveying direction along the arched line, and is rotationally driven in the conveying direction of the intermediate transfer belt 18 as shown by the arrow in the figure. The flexible endless sleeve-shaped intermediate transfer belt 18 is pressed against the image carrier 17 so as to cover it from the upper side. Therefore, the pressure between the image carrier 17 and the intermediate transfer belt 18 and the nip width are It can be adjusted by controlling the tension applied to the intermediate transfer belt 18 by the tension roller 14, the arrangement interval of the image carrier 17, the curvature of the arch, and the like.

The drive roller 12 also serves as a backup roller for the secondary transfer roller 39. The peripheral surface of the drive roller 12 has, for example, a thickness of about 3 mm and a volume resistivity of 10 ⁵ Ω.
A rubber layer of cm or less is formed, and is grounded via a metal shaft to serve as a conductive path of a secondary transfer bias supplied via the secondary transfer roller 39. By thus providing the driving roller 12 with a rubber layer 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 18, and the deterioration of image quality is prevented. can do. Further, by making the diameter of the drive roller 12 smaller than the diameters of the driven roller 13 and the backup roller 14, 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 intermediate transfer belt 18 is driven by the driving roller 1
2, the image forming stations Y, M, C, and K are arranged in a direction inclined to the right side in the figure with respect to No. 2, and in a corresponding direction to the drive roller 12 in an inclined arch shape in the direction inclined to the right side in the figure. It may be arranged along with, that is, symmetrically with FIG.

The cleaning means 15 is provided on the side of the belt surface 18a facing downward in the conveying direction, and conveys the collected toner and a cleaning blade 15a for removing the toner remaining on the surface of the intermediate transfer belt 18 after the secondary transfer. The toner carrying member 15b is provided. The cleaning blade 15 a is used for the intermediate transfer belt 18 to the driven roller 13.
Is abutted on the intermediate transfer belt 18 at the winding portion of. Further, on the back surface of the intermediate transfer belt 18, the image carrier 17 of each of the image forming stations Y, M, C and K described later is provided.
The primary transfer member 16 is in contact with the primary transfer member 16 and a transfer bias is applied to the primary transfer member 16.

The exposing means 6 is arranged in a space formed obliquely below the image forming unit 7 arranged obliquely, and the cooling means 8 is arranged in a space above the side surface of the exposing means 6. . A control unit and a power supply unit may be arranged on the side surface of the exposure unit 6 and the space below the cooling unit 8. Further, a paper feeding unit 10 is arranged at the bottom of the housing 2 below the exposure means 6. The exposure means 6 is
The whole is housed in a case, and the case is arranged in a space formed obliquely below the belt surface facing downward in the transport direction. At the bottom of the case, a polygon mirror motor 21a,
A single scanner means 21 composed of a polygon mirror (rotary polygon mirror) 21b is horizontally arranged to be exposed to the outside of the case from the bearing portion, and a single f-θ lens 22 and a reflection mirror are provided in the optical path B. 23 is provided, and the scanning optical paths y, m, c, k of the respective colors are provided above the reflection mirror 23.
A plurality of folding mirrors 24 are arranged so as to be non-parallel to the image carrier 17 and folded back.

In this way, the polygon mirror motor 21a,
By arranging the polygon mirror 21b horizontally, the force acting in the radial direction of the bearing can be eliminated, so that the rotational speed increases and the load on the bearing increases as the speed and resolution of the image forming apparatus increase. Even so, it is possible to reduce heat generation of the bearing portion, reduce temperature fluctuations in the apparatus, and provide an image forming apparatus with high image quality. Further, by providing the folding mirror 24, the scanning optical paths y, m,
By bending c and k, the height of the case can be reduced, and the size can be reduced. The folding mirror 24 is arranged so that the scanning optical paths of the image forming stations Y, M, C, and K to the image carrier 17 have the same length.

In the exposure means 6 having the above structure,
The image signal corresponding to each color from the polygon mirror 21b
The image carrier 17 of each of the image forming stations Y, M, C, and K is emitted by a laser beam modulated and formed based on a common data clock frequency, passes through an f-θ lens 22, a reflection mirror 23, and a folding mirror 24. To a latent image. In this way, from the polygon mirror 21b of the exposure unit 6 to the image forming units 7, the image carrier 17 is formed.
By configuring the lengths of the optical paths up to (optical path length) to be substantially the same, the scanning widths of the light beams scanned in the respective optical paths are also substantially the same, which is special for the formation of image signals. No configuration required. Therefore, the laser light source can be modulated and formed based on the common data clock frequency, even though the laser light source is modulated corresponding to the different color images by the different image signals, and the common reflection surface is used. It is possible to prevent a color shift caused by a relative difference in the sub-scanning direction and to configure a color image forming apparatus having a simple structure and inexpensive.

Further, when the plurality of laser beams are reflected from the common position of the common reflection surface of the common polygon mirror 21b to deflect and scan each image carrier 17, the accuracy of the reflection surface and the rotation of the polygon mirror 21b. The precision is canceled and the plurality of laser beams are uniformly deflected and scanned, and the image jitter can be reduced by the deflected scanning.

Further, in the present embodiment, the scanning optical system is arranged below the apparatus to minimize 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. It is possible to prevent deterioration of image quality. Particularly, by arranging the scanner means 21 at the bottom of the case, the polygon motor 21a
It is possible to minimize the vibration applied to the entire case by itself, and prevent deterioration of image quality. Further, by providing only one polygon motor 21a as a vibration source, it is possible to minimize the vibration applied to the entire case.

A cooling means 8 comprising a blower fan is provided on the side surface of the housing 2 so that the internal air is guided in the direction of the arrow shown in the drawing to radiate heat from the exposing means 6 and other heat generating portions. Therefore, the temperature rise of the polygon motor 21a is suppressed, image quality deterioration is prevented, and the polygon motor 21 is prevented.
The life of a can be extended.

In the present embodiment, the image stations Y, M, C, and K are arranged in an oblique direction, and the image carrier 17 is arranged in parallel upward along an oblique arch-shaped line for intermediate transfer. Due to the pressure contact with the belt surface 18a of the belt 18 which faces downward in the conveying direction, the toner storage container 26 is arranged obliquely downward. Therefore, the developing means 2
0 has a special configuration. FIG. 2 is an enlarged cross-sectional view of the image forming section including the developing means and the image carrier shown in FIG.

The developing means 20 includes a toner storage container 26 for storing toner (mesh portion in the figure), as shown in FIG.
The toner storage portion 2 formed in the toner storage container 26
7, a toner stirring member 29 disposed in the toner storage portion 27, a partition member 30 partitioned and formed on the upper portion of the toner storage portion 27, and a toner supply roller 31 disposed above the partition member 30. A flexible blade 32 provided on the partition member 30 and in contact with the toner supply roller 31, a developing roller 33 arranged in contact with the toner supply roller 31 and the image carrier 17, and a developing roller 33. The regulation blade 34 is in contact with the regulation blade 34.

The image carrier 17 is rotated in the conveying direction of the intermediate transfer belt 18, 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.

Further, 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.

Further, the developing means 20 includes a developing roller 3
A developing roller exposing portion 20a is formed in the vicinity of 3, and a corona charging means 19 which is a charging means is formed with an upward opening 19a facing the image carrier 17.
At this time, when the upward opening 19a of the corona charging unit 19 is located below the developing roller exposing portion 20a, the toner spills from the developing roller exposing portion 20a due to gravity,
There is a problem that the corona charging means 19 gets into the corona charging means 19 through the upward opening 19a and stains the corona charging means 19.

Therefore, in the present embodiment, the upward opening 19a is provided on the intermediate transfer belt 18 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 paper feeding unit 10 includes a paper feeding cassette 35 in which recording media P are stacked and held, and a pickup roller 36 for feeding the recording media one by one from the paper feeding cassette 35.
Is equipped with. The paper transport unit 11 includes a pair of gate rollers 37 (one roller is provided on the housing 2 side) that defines the timing of feeding the recording medium P to the secondary transfer unit, the drive roller 12, and the intermediate transfer belt 18. A secondary transfer roller 39 as a secondary transfer means that is pressed against
This can be said to include the main recording medium conveyance path 38, the fixing means 40, the paper discharge roller pair 41, and the 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 the fixing means 40 and is rotatable with respect to the fixing roller pair 4.
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 obliquely above the belt surface 18b that is upward in the transport 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 18, and the image forming unit, and to reduce the frequency of performing the 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.

In the present embodiment, the intermediate transfer belt 1
Since 8 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 compactness 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.
8 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 (personal computer or the like) not shown is input to the control unit of the image forming apparatus 1, the images of the image forming stations Y, M, C and K are displayed. The carrier 17, each roller of the developing device 20, and the intermediate transfer belt 18 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) To the primary transfer member 16 of the intermediate transfer belt 18, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied, and the toner image formed on the image carrier 17 is transferred to the intermediate transfer belt at the primary transfer portion. With the movement of 18, the images are sequentially transferred and superposed on the intermediate transfer belt 18. (7) Intermediate transfer belt 18 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 transferred by the secondary transfer roller 39 pressed toward the drive roller 12 of the intermediate transfer belt 18 by a pressing mechanism (not shown). A bias having a reverse polarity to that of the transfer image is applied, and the primary transfer image formed on the intermediate transfer belt 18 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 18 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).

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and conventionally known or well-known techniques can be replaced or added as necessary. For example, in the present embodiment, the plurality of image carriers 17 are arranged in parallel along the oblique arch line, and these and the intermediate transfer belt 18 are pressed against each other. However, the vertical arch form and the horizontal arch form are provided. Line, or the line may be a straight line. Also in this case, the position of the polygon mirror motor 21a can be selected to be a thermally advantageous position by the arrangement of the folding mirror 24. Also, the backup roller 14 is omitted,
The intermediate transfer belt 18 may be stretched only by the driving roller 12 and the driven roller 13. Furthermore, although the drive roller 12 is arranged below the driven roller 13 above, the driven roller 13 may be arranged below and the drive roller 12 is arranged above. In the present invention, the intermediate transfer belt and the paper transport belt are collectively defined as a transfer belt.

[0042]

As is apparent from the above description, according to the present invention, a plurality of image carriers arranged in parallel and an exposure for forming a latent image by exposing the plurality of image carriers with a laser beam. And a plurality of developing means for developing the latent images formed on the plurality of image carriers, and the exposing means includes a plurality of laser light sources modulated by image data corresponding to the plurality of image carriers. And a common rotating polygon mirror which is horizontally arranged and deflects and scans a laser beam of each laser light source on a common reflecting surface, and an optical path by which the laser beam deflects and scans non-parallel to each image carrier, , A plurality of developing means for developing the latent image formed on each of the plurality of image bearing members, a recording means for transferring and recording the developed toner images of each of the plurality of image bearing members in an overlapping manner, and a recording toner image And a fixing means for fixing, Chakushudan Since was placed away from the exposure means position, without the self-weight of the rotating body acts on the bearing, the bearing,
The stability of the center of gravity is excellent, disturbance effects such as driving vibration are small, and the life of the bearing can be improved. Therefore, even if the number of rotations of the drive motor increases, the heat generated from the bearing portion that occupies most of the heat generated by the rotary polygon mirror and its vicinity is reduced, and the heat generated by the rotary polygon mirror is reduced as a whole. However, stable deflection scanning of the laser beam is possible.

Furthermore, when the laser beams of a plurality of laser light sources are reflected and deflected and scanned at a common position on the common surface,
The precision of the reflecting surface and the precision of rotation of the rotary polygon mirror are canceled, and the plurality of laser beams are uniformly deflected and scanned, so that image formation without image jitter by deflection scanning is possible.

In the rotary polygon mirror, the bearing portion is fitted in the case of the exposing means and a part is exposed to the outside of the case. The optical path is radially deflected while the laser beam is reflected back from the common reflecting surface of the rotary polygon mirror. Place multiple mirrors to scan,
Since the length from the common reflecting surface of the rotating polygon mirror to each image carrier is approximately the same, and the plurality of laser light sources are arranged at positions where each laser beam is radially reflected by the common reflecting surface of the rotating polygon mirror. , Which can efficiently radiate heat to the outside, uses a common data clock frequency despite the fact that the exposure means is made compact and inexpensive, and a plurality of laser light sources are modulated by different image signals. As a result, a relative difference in the sub-scanning direction can be prevented from occurring, and stable image formation without color misregistration becomes possible.

The plurality of image carriers are arranged in parallel upward along the oblique arch line, the exposing means is arranged obliquely below the plurality of image carrier arrangements, and the fixing means is the plurality of image carrier bodies. Since it is arranged diagonally above and on the opposite side of the exposing means, the rotary polygon mirror can be arranged at a position away from the image forming side such as the exposing part, the transferring part, and the fixing part, and heat is trapped inside the exposing part. This can be prevented, the temperature fluctuation of the exposure means can be suppressed, and the bearing portion can be cooled efficiently.

The recording means includes a flexible and endless intermediate transfer medium that is pressed against and driven by each image carrier along an oblique arch line, a paper transport path for transporting recording paper, and the paper transport. A transfer means for transferring the toner image from the intermediate transfer medium onto the recording paper on the road, and a fixing means arranged on the paper conveying path;
Further, the rotary polygon mirror is arranged on the lower side of one side surface, is positioned on the upper side of the outside of the body, and is also on the opposite side of the intermediate transfer body together with the exposure means, so that heat can be efficiently dissipated from each heat generating portion, and the It is possible to reduce the thermal influence of the large fixing unit on the exposure unit.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of an image forming unit including a developing unit and an image carrier shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Housing, 3 ... Door body, 6 ... Exposure unit, 7 ... Image forming unit, 8 ... Cooling means, 9
... transfer belt unit, 10 ... paper feeding unit, 11 ... paper transport unit, 15 ... cleaning means, 17 ... image carrier, 18 ... intermediate transfer belt, 20 ... developing means, 21 ... scanner means, 21b ... rotary polygon mirror, 40 ... Fixing means

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/01 112 G03G 15/04 111 2H076 15/04 111 15/20 101 5C051 15/20 101 H04N 1/036 Z 5C072 H04N 1/036 B41J 3/00 D 1/113 H04N 1/04 104A (72) Inventor Yujiro Nomura 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation F-term (reference) 2C362 BA51 BA54 BA87 BA90 CA22 CA39 CB59 DA06 DA19 DA31 DA33 DA34 2H030 AA06 AB02 BB02 BB21 BB42 2H033 AA41 BA02 BB00 2H045 AA23 BA22 BA34 DA41 2H071 DA02 DA03 DA12 DA15 EA04 EA18 2H076 AB06 AB12 AB18 AB81 EA01 EA04 5C051 AA02 CA07 DA02 DB02 DB22 DB24 DB30 DC04 DC07 5C072 AA03 BA12 BA19 HA02 HA06 HA09 HA13 QA14 XA05

Claims (10)

[Claims] 1. A plurality of image forming units arranged in parallel to form a latent image on an image carrier and developing the latent image formed by a developing unit, and a latent image formed by exposing a laser beam to each of the image carriers. In an image forming apparatus including an exposure unit that forms an image, the exposure unit includes a plurality of laser light sources that are modulated by image data corresponding to the plurality of image carriers, and a horizontal arrangement of each of the laser light sources. An image forming apparatus comprising: a common rotating polygon mirror for deflecting and scanning a laser beam on a common reflecting surface; and an optical path for deflecting and scanning the laser beam non-parallel to each of the image carriers. . 2. A plurality of image forming means arranged in parallel to form a latent image on an image carrier and developing the formed latent image by a developing means, and a latent image by exposing a laser beam on each of the image carriers. In the image forming apparatus, there is provided an image forming apparatus including: an exposing unit that forms an image; a recording unit that superimposes and records the developed toner images on the respective image carriers; and a fixing unit that fixes the recorded toner images. Means, a plurality of laser light sources modulated by image data corresponding to the plurality of image carriers,
A common rotating polygon mirror that is horizontally arranged and deflects and scans a laser beam of each of the laser light sources by a common reflecting surface, and an optical path that the laser beam deflects and scans non-parallel to each of the image carriers, The image forming apparatus, wherein the fixing unit is arranged at a position apart from the exposing unit. 3. The image forming apparatus according to claim 1, wherein the rotary polygon mirror has a bearing portion fitted in a case of the exposure means and a part of the rotary polygon mirror is exposed to the outside of the case. 4. A plurality of mirrors are arranged in the optical path for radially deflecting and scanning while a laser beam is reflected back from a common reflection surface of the rotary polygon mirror, and each of the mirrors is arranged from the common reflection surface of the rotary polygon mirror. 3. The image forming apparatus according to claim 1, wherein the length up to the image carrier is substantially the same. 5. The plurality of image bearing members are arranged in parallel upward along an oblique arch-shaped line, and the exposure unit comprises:
The image forming apparatus according to claim 1, wherein the image forming apparatus is arranged diagonally below the plurality of image carriers. 6. The image forming apparatus according to claim 1, wherein the plurality of laser light sources are arranged at positions where the respective laser beams are radially reflected by a common reflecting surface of the rotary polygon mirror. 7. The image forming apparatus according to claim 1, wherein the laser beams of the plurality of laser light sources are reflected at a common position on the common reflection surface and deflected and scanned. 8. The plurality of image carriers are arranged in parallel upward along an oblique arch-shaped line, and the exposure unit comprises:
3. The image according to claim 2, wherein the fixing unit is arranged diagonally below the plurality of image carrier arrangements, and the fixing unit is arranged diagonally above the plurality of image carrier arrangements on the opposite side of the exposing unit. Forming equipment. 9. The recording means comprises a flexible and endless intermediate transfer medium that is pressed against and driven by each of the image carriers along the oblique arch line, and a paper transport path for transporting recording paper. 9. The image forming apparatus according to claim 8, further comprising: a transfer unit configured to transfer a toner image from the intermediate transfer medium onto a recording sheet on the paper transport path, and the fixing unit disposed on the paper transport path. . 10. The image forming apparatus according to claim 2, wherein the rotary polygon mirror is disposed below one side surface, and the fixing unit is disposed above the other side surface.