JP2003167433A - Developing cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate influence by driving reaction caused when a driving gear drives a driven gear, to prevent the abutting state of a developing roll or an abutting roller from getting unstable, and to eliminate the factor of the driving vibration of the gear so as to restrain an image defect. <P>SOLUTION: This image forming apparatus is equipped with a developing cartridge 20 which is constituted to be attachable/detachable, and where the driven gear 55 is driven through the driving gear 54 of a main body, and toner is supplied to the developing roll 33 so as to develop a latent image formed on an image carrier 17 by the roll 33, and the image carrier 17 carrying and feeding a toner image. The apparatus has a turning supporting point 51 arranged near the meshing point of the gear 54 with the gear 55 and turnably supported in the main body, and is constituted so that the roll 33 may be energized to be turned toward the image carrier 17 by the energizing means 56 of the main body. By canceling the driving reaction or the like caused when the gear 54 drives the gear 55, the influence thereby is restrained. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is configured to be detachable from a main body, a driven gear is driven through a drive gear of the main body, toner is supplied to a developing roller, and the toner is formed on an image carrier by the developing roller. The present invention relates to a developing cartridge for developing the formed latent image and an image forming apparatus including the developing cartridge.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus, a developing cartridge is detachably attached to an image carrier which carries and conveys a toner image, toner is stored in the developing cartridge and supplied to a developing roller, and the image is formed by the developing roller. The latent image formed on the carrier is developed. The developing roller can be developed by bringing the developing roller into contact with the image carrier at a predetermined contact pressure, or by developing the developing roller at a predetermined gap from the image carrier. The contact roller is attached to a part of the developing roller, contacts the image carrier, and is driven to rotate, and is provided to form the basis of the relative positional relationship between the developing roller and the image carrier.

[0003]

The developing cartridge as described above has various problems because it is detachable. For example, since the developing roller and the supply roller of the developing cartridge are driven through the driven gear from the driving gear of the image forming apparatus main body, the contact rollers that form the basis of the relative positional relationship between the developing roller and the image carrier are contacted. The contact state becomes unstable, and rotational jitter of the developing roller or the image bearing member occurs due to driving vibration factors of both the driving gear and the driven gear, resulting in image defects. This is because the driving reaction force acts as a moment in the direction of moving the developing cartridge closer to or away from the image carrier when the driving gear drives the driven gear.

Further, the contact roller is driven by the image carrier with the developing roller as a spindle, or is driven by the developing roller and rubs against the image carrier to rotate. Even if there is, a driving reaction force is generated. If there is a difference between the rotational peripheral speeds of the two, even if the rotational peripheral speed of the contact roller provided on the developing roller is faster than the rotational peripheral speed of the image carrier, the rotation of the image carrier is reversed. Even when the rotation peripheral speed of the contact roller provided on the developing roller is slower than the peripheral speed, a driving reaction force is generated in accordance with the difference in peripheral speed, and the contact state of the contact roller becomes unstable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and eliminates the influence of a driving reaction force generated when a driving gear drives a driven gear. The contact state of the rollers is prevented from becoming unstable, and the image defect is suppressed by eliminating the drive vibration factor of the gear.

To this end, the present invention is constructed so that it can be attached to and detached from the main body of the image forming apparatus, the driven gear is driven through the drive gear of the main body, toner is supplied to the developing roller, and the developing roller puts it on the image carrier. In an image forming apparatus equipped with a developing cartridge for developing the formed latent image and an image carrier for carrying and conveying a toner image, the image forming apparatus is disposed near the meshing point of the driving gear and the driven gear and is rotated by the main body. It is characterized in that it has a rotation fulcrum movably supported and is configured so that the developing roller is rotatably urged toward the image carrier by the urging means of the main body.

The rotation fulcrum is arranged in the vicinity of a position for supporting the weight of the developing cartridge. The rotation fulcrum has a supply roller for supplying toner to the developing roller, and the rotation fulcrum is at least the development roller. And characterized in that it is arranged in the vicinity of a position for supporting the own weight of the supply roller,
The rotary fulcrum is provided with a contact roller that is mounted on a part of the developing roller and abuts on the image carrier to be driven to rotate and forms a basis of a relative positional relationship between the roller and the image carrier. Is arranged in the vicinity of the action direction of the reaction force generated when the contact roller abuts on the image carrier and is driven, and in the vicinity of the position for supporting the self-weight of the developing cartridge. is there.

Further, the rotation fulcrum is supported so as to face the developing cartridge attachment / detachment direction in the vicinity of a position where a force acting when the driven gear is driven from the driving gear acts in the supporting direction. The developing cartridge has guide means in the attaching / detaching direction that forms a pair with the rotation fulcrum, and the guide means is supported with a clearance in the direction of being rotationally biased by the biasing means. The driven gear is disposed near a position orthogonal to the mounting / removing direction of the developing cartridge with respect to the driving gear, and the developing cartridge is fixed to a predetermined position of the main body while being rotationally biased by the biasing means. It is characterized by having a locking means locked at the position.

[0009]

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 sectional view showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a side view from the driving gear and driven gear sides, and FIG. 3 is a mounting portion and rotation of a developing cartridge. FIG. 4 is a diagram showing the presence or absence of contact rollers that form the basis of the relative positional relationship between the developing roller and the image bearing member, and their configuration examples. 17 in the figure
Is an image carrier, 20 is a developing cartridge, 31 is a supply roller, 33 is a developing roller, 52 is a developing device mounting guide pin, 51 is a rotary fulcrum shaft of the developing device, 53 is a supporting member of the developing device, and 54 is a driving device. A gear, 55 is a driven gear, 56 is an urging spring, 57 is a contact roller, and 59 is a detachable handle.

In FIG. 1, the image forming apparatus according to the present embodiment is configured such that the developing cartridge 20 is detachably attached to the main body in the direction of S in the drawing. The supporting member 53 of the developing device is
A member for supporting the developing cartridge 20 of the main body, and a slit portion for mounting and supporting the developing cartridge 20 is provided.
The rotation fulcrum shaft 51a of the developing device of the developing cartridge 20 is
It is a rotation fulcrum rotatably supported by the slit portion of the supporting member 53 of the developing device, and is a mounting guide pin 52a of the developing device.
Is provided in a slit portion of a supporting member 53 of the developing device with a clearance that allows the developing roller 33 of the developing cartridge 20 to move toward the image carrier 17.

The biasing spring 56 is a biasing means which is provided on the main body side and biases the developing cartridge 20 in the direction of R1 in the drawing. By the biasing spring 56, the image carrier 17
The developing roller 33, which rotates in proximity to and develops the toner, is urged in the direction of the image carrier 17 and in the direction of R2 in the figure. The drive gear 54 is provided on the main body side, and the developing roller 33, the supply roller 31, the toner stirring member 29, and the like of the developing cartridge 20 are driven from the drive gear 54 through the driven gear 55.

As described above, the direction R1 is the direction in which the developing cartridge 20 is biased by the biasing spring 56, and the direction R2.
Is the direction of the image carrier 17 in which the developing roller 33 is rotationally biased by the bias, and at this time, the developing cartridge 2
0 is rotatably supported about the rotation fulcrum shaft 51. The direction S is the mounting direction of the developing cartridge 20, and the drive gear 54 meshes with the driven gear 55 near the rotation fulcrum shaft 51 in the direction orthogonal to the line of the mounting direction in the direction of the arrow shown. It is also the direction in which the driving reaction force acts when driven. Further, in the direction M, when the developing roller 33 or a contact roller mounted on a part of the developing roller 33 comes into contact with the image carrier 17 and is driven to rotate, a reaction force due to a difference in rotational peripheral speed between them acts. Direction, and this line of action also passes in the vicinity of the rotation fulcrum shaft 51. It is desirable that the direction in which these reaction forces act matches the mounting direction of the developing cartridge 20 in order to stabilize the mounted state,
Further, it is desirable that the rotation fulcrum shaft 51 is located on or near those lines in order to stably maintain the state when the developing roller 33 is biased in the direction R2 of the image carrier 17.

As shown in FIG. 1, the developing cartridge 20 is provided with a developing device mounting guide pin 52a and a developing device rotation fulcrum shaft 51a on one axial side, for example, on the right side, and as shown in FIG. A mounting guide pin 52b of the developing device and a rotary fulcrum shaft 51b of the developing device are respectively provided on the other axial direction on the opposite side, for example, on the left side surface, and correspondingly to the supporting members 53a and 53b of the developing device on the main body side. A slit portion is provided. The developing cartridge 20 is mounted by inserting the rotary fulcrum shaft 51 of the developing device and the mounting guide pin 52 of the developing device along the slit portion.

When the developing cartridge 20 is mounted on the main body, as shown in FIGS. 1 and 2, the rotary fulcrum shafts 51a and 51b of the developing devices are provided at the bottoms of the slits of the supporting members 53a and 53b of the developing devices. It is rotatably supported as a rotation fulcrum, and on the entrance side of the slit portion, the mounting guide pin 5 of the developing device is attached.
2a and 52b are supported with a clearance movable about the pivot. Therefore, when the developing cartridge 20 is rotationally biased in the direction of R3 as shown in FIG. 3, the mounting guide pins 52a and 52b of the developing device are rotated about the rotational fulcrum shafts 51a and 51b of the developing device. Fulcrum) and a predetermined angle range determined by the clearance, dotted line 52
It moves to the positions indicated by a'and 52b '. If the image carrier 17 is not provided, the mounting guide pins 52a, 52b
Is locked at a predetermined position where it abuts on the wall of the slit portion, and when the image carrier 17 is moved to a predetermined position and comes into contact with the developing roller 33 or a contact roller attached to a part of the developing roller, It moves to a desired positional relationship according to the rotational biasing by the biasing spring 56.

The position of the rotation fulcrum shaft 51 of the developing device of the developing cartridge 20, that is, the position of the rotation fulcrum, excludes the influence of the drive reaction force generated when the driving gear drives the driven gear, and It is important to prevent the contact state from becoming unstable. First, in order to cancel the drive reaction force generated when the drive gear 54 drives the driven gear 55 at the rotation fulcrum, as shown in FIG. 1, the drive gear 54 and the driven gear 55 are
And the driving direction of the driving gear 54 and the driven gear 55 so as to act in the mounting direction of the developing cartridge 20. When the driving reaction force generated when the driving gear 54 drives the driven gear 55 is cancelled, the developing cartridge 20 is rotatably supported at the rotation fulcrum, so that the developing cartridge 20 is affected by the driving reaction force. Instead, the developing roller 33 is urged to rotate in the direction of the image carrier 17 by the urging spring 56 which is an urging unit provided on the main body side.

Between the developing roller 33 and the image carrier 17, there are provided contact rollers 57a and 57b which form the basis of the relative positional relationship, as shown in FIGS. 4 (A) and 4 (B). The contact roller may not be provided as shown in FIG. As shown in FIG.
When the developing gap G is formed between the developing roller 33 and the image carrier 17 as shown in FIG.
The material of No. 3 has no particular limitation and there is a degree of freedom in selection, but even if the contact rollers 57a and 57b are provided as shown in FIG. 4B, the contact rollers are provided as shown in FIG. 4C. When the developing roller 33 is brought into contact with the image carrier 17 even without the elastic member, an elastic body is used for the developing roller 33.

When the contact roller 57 is provided, if there is an influence of the driving reaction force, that is, if it acts as a moment in the direction of moving the developing cartridge 20 toward or away from the image carrier 17, the developing roller 33 and Image carrier 1
The contact state of the contact roller 57, which forms the basis of the relative positional relationship of No. 7, becomes unstable, and rotation jitter of the developing roller 33 or the image carrier 17 occurs due to factors such as driving vibration of both gears 54 and 55. Image defects occur. However, such image defects can be suppressed by canceling the driving reaction force as described above.

Further, the rotation fulcrum shaft 51a of the developing device is disposed near the position supporting the weight of the developing cartridge 20, at least near the position supporting the weight of the developing roller 33 and the supply roller 31. In the drawing, the rotation fulcrum shaft 51a of the developing device, which serves as the rotation fulcrum, is arranged below the developing cartridge 20. However, the developing cartridge 20 is supported at its own weight or at least the developing roller 33.
In addition, if it is a position that supports the own weight of the supply roller 31, it may be arranged above. As a result, it is possible to prevent the rotation biasing force from being influenced by the own weight of the developing cartridge 20 and the own weight of the developing roller 33 and the supply roller 31.

In particular, among the constituent elements of the developing cartridge 20, the developing roller 33 and the supply roller 31 often have a larger weight than the other constituent elements. Since the contact state of the contact roller 57 that contacts the carrier 17 is stable, the degree of freedom in selecting the constituent materials of the developing roller 33 and the supply roller 31 is wide.
Even if you select it based on an aluminum material that has a relatively low specific gravity, or if you select it based on an iron material that has a relatively high specific gravity, it will not affect the entire development cartridge and ignores its own weight. It becomes possible to select the cost advantage.

As a structure for suppressing the similar influence, a rotation fulcrum is arranged in the vicinity of the action direction M of the reaction force generated when the contact roller 57 contacts the image carrier 17 and is driven, or the developing cartridge is used. It is also effective to dispose in the vicinity of the position supporting the own weight of 20 and in the vicinity of the action direction of the reaction force generated when the contact roller 57 contacts the image carrier 17 and is driven thereby. Further, at the rotation fulcrum, the developing cartridge 20 is supported so as to be opposed to the mounting direction, and the acting force acting when the driven gear 55 is driven from the driving gear 54 as shown by an arrow S in FIG. It is also effective to adopt a configuration in which it is arranged in the vicinity of the position where it acts toward.

The abutment roller 57 provided on the image carrier 17 and the developing roller 33 comes into contact with the developing roller 33 by being urged by the urging spring 56 provided on the main body to rotate in the direction R2 of the image carrier 17. Each is rotationally driven in the direction of the arrow shown. At this time, the contact roller 57 is driven and driven by the image carrier 17 as a support shaft of the developing roller 33, or rotates by rubbing against the image carrier 17 driven by the developing roller 33. Even in the state of, the driving reaction force is generated. Then, when there is a difference between the rotational peripheral speeds of the two, the rotational peripheral speed of the contact roller 57 provided on the developing roller 33 is faster than the rotational peripheral speed of the image carrier 17 according to the peripheral speed difference. In this case, a driving reaction force is generated in the direction M indicated by the solid line in the figure,
On the contrary, when the rotation peripheral speed of the contact roller 57 provided on the developing roller 33 is slower than the rotation peripheral speed of the image carrier 17, a driving reaction force is generated in the direction opposite to the direction M shown by the solid line arrow.

Therefore, when the rotation fulcrum 51 is arranged in the vicinity of the direction M for canceling the action of the reaction force, the developing roller 33 is moved in the direction R of the image carrier 17 by the biasing spring 56.
It is possible to prevent the rotationally biased state from becoming unstable due to this reaction force when being rotationally biased to 2. Although the rotation fulcrum is arranged below the developing cartridge 20 in the figure,
If the contact roller 57 is in the vicinity of the direction canceling the action of the reaction force generated when the contact roller 57 contacts the image carrier 17 and is driven, it may be provided above. Further, since the acting force when the driven gear 55 is driven acts in the supporting direction S, the supporting state of the developing cartridge 20 is stabilized and the relative relationship with the image carrier 17 is maintained in a preferable relationship. It

Further, in the configuration shown in FIG. 1, the driven gear 55
To the drive side driven by the drive gear 54,
The mounting guide pin 52 is arranged on the other side apart from the driving side, and has a pair of structures arranged at least at two positions. The rotation fulcrum 51 on the drive side is rotatably supported at a predetermined position in the mounting direction and a direction orthogonal to the mounting direction, and the mounting guide pin 52 on the other side is supported and abutted in the mounting direction. The roller 57 is supported with a movable clearance provided as a reaction when the roller 57 is biased by the image carrier 17. As a result, the contact relationship between the developing cartridge 20 and the image carrier 17 is a so-called three-point contact structure, so that the contact state is stable.

The driven gear 55 is arranged near the drive gear 54 in a position orthogonal to the mounting and demounting direction of the developing cartridge 20. As a result, when the developing cartridge 20 is attached or detached, the driven gear 55 can be easily engaged with or disengaged from the drive gear 54, so that an auxiliary mechanism for stabilizing the engagement or disengagement is not necessary.

When the developing cartridge 20 is mounted on the main body, the developing roller 33 is moved by the urging spring 56 so that the image bearing member 1 is supported.
7 is urged to rotate in the direction of 7, and locked at a predetermined position moved by the clearance between the mounting guide pin 52 and the slit portion to stand by, and then the image carrier 17 is moved to a predetermined position and abutted. The structure is such that when it comes into contact with the contact roller 57, it moves to a desired positional relationship. As a result, there is no restriction on the positional relationship with the image carrier 17 when the developing cartridge 20 is attached or detached, so that the attaching and detaching operation becomes easy. In addition, since the function of configuring the relative position relationship between the developing cartridge 20 and the image carrier 17 is divided into two parts, it is possible to realize a stable relative position structure without undue operation. become.

Next, the internal structure of the developing cartridge 20 will be described. As shown in FIG. 1, the developing cartridge 20 includes a toner storage container 26 for storing toner (mesh portion in the figure), a toner storage portion 27 formed in the toner storage container 26, and a toner storage portion 27. A toner stirring member 29 provided, a partition member 30 partitioned and formed on the upper portion of the toner storage unit 27, a toner supply roller 31 disposed above the partition member 30, and a toner supply roller provided on the partition member 30. Flexible blade 32 abutting 31
A developing roller 33 arranged so as to contact the toner supply roller 31 and the image carrier 17;
And a regulation blade 34 that abuts against.

The image carrier 17 is rotated in the carrying direction of the image transfer carrying means, 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.

FIG. 5 is an oblique external view showing an embodiment of the developing cartridge according to the present invention, FIG. 6 is an oblique external view from the opposite side of the developing cartridge shown in FIG. 5, and FIG. 7 is a plurality of developing cartridges arranged in parallel. FIG. 8 is a schematic sectional view of the overall configuration showing an embodiment of a color image forming apparatus in which a plurality of developing cartridges are mounted.

The developing cartridge according to the present embodiment described above is provided with the rotation fulcrum shaft 51, the mounting guide pin 52, and the detachable grip 59 on both side surfaces as shown in FIGS. The developing cartridge is lifted, and the rotation fulcrum shaft 51 and the mounting guide pin 52 are mounted along the slit of the supporting member as described above. Then, for example, as shown in FIG.
When a plurality of developing cartridges having Y, magenta developing roller 33M, and cyan developing roller 33C are arranged in parallel, the rotation fulcrum shaft 51 and the mounting guide pin 52 are attached to the adjacent developing cartridges to wrap. Come to do. FIG. 8 is a schematic cross-sectional view of the overall configuration showing the embodiment of the color image forming apparatus in which four developing cartridges are mounted in this manner.

In FIG. 8, the image forming apparatus 1 of 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 which is mounted on the front surface of the housing 2 so as to be openable and closable. An exposure unit (exposure means) 6, an image forming unit 7, a transfer belt unit 9 having an image transfer / transport means, and a paper feed unit 10 are provided in the housing 2, and paper is transported in the door body 3. A unit 11 is arranged. 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 is provided with image forming stations Y (yellow), M (magenta), C (cyan) and K (black) for forming a plurality of (four in the present embodiment) images of different colors. ing. 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. It has a cartridge 20. These image forming stations Y, M, C, K are arranged in parallel below the transfer belt unit 9 along an oblique arch line so that the image carrier 17 faces upward. The image forming stations Y, M, C, K may be arranged in any order.

The transfer belt unit 9 includes a drive roller 12 disposed below the housing 2 and rotated by a drive source (not shown), a driven roller 13 disposed obliquely above the drive roller 12, and a backup roller. An image transfer conveying unit 1 including a (tension roller) 14 and an intermediate transfer belt which is stretched between these three rollers and at least two rollers and is circularly driven in the direction of the arrow (counterclockwise X).
8 and a cleaning unit 15 that comes into contact with the surface of the image transfer / transport unit 18. The driven roller 13, the backup roller 14, and the image transfer conveying means 18 are arranged in a direction inclined to the left side of the drawing with respect to the drive roller 12, whereby the belt conveying direction X when the image transfer conveying means 18 is driven is downward. The belt surface 18a is positioned below, and the belt surface 18b whose transport direction is directed upward is positioned 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 brought into contact with the belt surface 18a of the image transfer / conveying means 18 facing downward in the conveying direction along the arched line, and is rotationally driven in the conveying direction of the image transfer / conveying means 18 as indicated by an arrow in the figure. Since the flexible image transfer conveying means 18 in the form of an endless sleeve is brought into contact with the image carrier 17 from the upper side at substantially the same winding angle, the image carrier 17 and the image transfer conveyer 18 are contacted with each other. The contact pressure between them and the nip width are adjusted by the tension roller 14 by the image transfer / conveying means 18
The tension can be adjusted by controlling the tension applied to, the arrangement interval of the image carrier 17, the winding angle (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 image transfer / conveying means 18, and the image quality is deteriorated. Can be prevented. 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 image transfer / conveying means 18 is arranged in a direction inclined to the right side of the drawing with respect to the driving roller 12, and correspondingly, the image forming stations Y, M, C and K are also arranged on the driving roller 12. On the other hand, they may be arranged along the oblique arch in the direction inclined to the right in the figure, that is, symmetrically with respect to FIG.

As described above, in the image forming apparatus of this embodiment, a plurality of image carriers 17 are arranged in parallel and each image carrier 17 is arranged.
A flexible image transfer conveying means 18 in the form of an endless sleeve having a predetermined wrapping angle is arranged in contact with the roller and stretched around at least two rollers 12 and 13 to be rotationally driven to convey the image. The means 18 has a structure in which tension is applied by one of the rollers 12 and 13 and the toner images on the image carrier 17 are sequentially superimposed and transferred. With this arrangement, a predetermined nip is easily formed at the contact portion between the image carrier 17 and the image transfer / conveying means 18 according to the winding angle, and the contact pressure at the contact portion also depends on the winding angle. Granted.

The primary transfer member 16 is arranged at a position in contact with the inside of the image transfer / conveying means 18 as a transfer bias applying means for successively superposing and transferring toner images to form an image. Due to the contact pressure application structure, it is not necessary to apply the pressing force for forming the transfer nip. Since it suffices to simply contact the image transfer / conveying means 18 as a means capable of ensuring energization, a conductive roller or a rigid contactor which rotates in contact with the image transfer / conveying means, or a conductive elastic member such as a leaf spring, or a resin. A conductive brush or the like formed of a fiber group such as can be used. Moreover, since it is not necessary to apply a pressing force, the primary transfer member 16 can be configured to contact the image transfer / conveying means 18 in an area narrower than the nip and apply the transfer bias.

The cleaning means 15 is provided on the side of the belt surface 18a facing downward in the conveying direction, and the cleaning blade 15a for removing the toner remaining on the surface of the image transfer conveying means 18 after the secondary transfer and the collected toner are conveyed. The toner transport member 15b is provided. The cleaning blade 15 a is in contact with the image transfer / conveyance means 18 at the portion where the image transfer / conveyance means 18 is wound around the driven roller 13. In addition, on the back surface of the image transfer transporting means 18,
The primary transfer member 16 is in contact with the image carrier 17 of each of the image forming stations Y, M, C, and K to be described later, 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. Further, a paper feeding unit 10 is arranged at the bottom of the housing 2 below the exposure means 6. Exposure means 6
Is entirely 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, the polygon mirror motor 21
a, a single scanner means 21 composed of a polygon mirror (rotary polygon mirror) 21b is horizontally arranged, and a laser beam from a plurality of laser light sources 23 modulated by image signals of respective colors is reflected by the polygon mirror 21b. In the optical system B which deflects and scans each image carrier, the single f-θ lens 22 and the scanning optical paths y, m, c, and k of the respective colors are turned non-parallel to the image carrier 17 and folded. A plurality of reflection mirrors 24 are arranged in the.

In the exposure means 6 having the above structure,
The image signal corresponding to each color from the polygon mirror 21b
It is emitted by a laser beam that is modulated and formed based on a common data clock frequency, passes through an f-θ lens 22, and a plurality of reflecting mirrors 24, and then, at each image forming station Y, M ,.
The C and K image carriers 17 are irradiated and a latent image is formed.
By providing the reflection mirror 24, the scanning optical paths y, m,
By bending c and k, the height of the case can be reduced, and the optical system can be made compact. Moreover, the reflection mirror 24 has the same scanning light path length to the image carrier 17 of each of the image forming stations Y, M, C, and K.
Are arranged. In this way, the optical path from the polygon mirror 21b of the exposure unit 6 to the image carrier 17 for each image forming unit 7 (optical path length) is configured to have substantially the same length, and scanning is performed in each optical path. The scanning widths of the generated light beams are substantially the same, and no special configuration is required for forming the image signal. 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.

The paper feed unit 10 includes a paper feed 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 feed 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 image transfer transport unit. Secondary transfer roller 39 as a secondary transfer means that is pressed against 18
A main recording medium conveyance path 38, a fixing unit 40, a paper discharge roller pair 41, and a double-sided printing conveyance path 42 are provided.

The fixing means 40 includes a heating element such as a halogen heater 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 image transfer / conveyance unit 18, and the image forming unit, and 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.
Color shift can be prevented.

In the present embodiment, since the image transfer / conveying means 18 is arranged in the direction inclined with respect to the driving roller 12, a wide space is created in the right space in the drawing, and the fixing means 40 is arranged in that space. The heat generated by the fixing unit 40 is transferred to the exposure unit 6, the image transfer / conveying unit 18, and the image forming stations Y, M, C, and K located on the left side. It 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 vibration of the scanning optical system of the exposure unit 6 due to the vibration given to the housing 2 by the drive system of the image forming means is minimized. Therefore, it is possible to suppress the deterioration of the image quality.

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, the rollers of the developing cartridge 20, and the image transfer / conveyance unit 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 roller 33. (5) The primary transfer member 16 of the image transfer / conveyance unit 18 includes:
A primary transfer voltage having a polarity opposite to the toner charging polarity is applied,
The toner images formed on the image carrier 17 are sequentially transferred onto the image transfer / conveying means 18 in the primary transfer portion in accordance with the movement of the image transfer / conveying means 18. (7) Image transfer / conveying means 1 for primary transfer of this primary image
In synchronism with the movement of 8, the recording medium P stored in the paper feed cassette 35 is fed to the secondary transfer roller 39 via the registration roller pair 37. (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 image transfer conveying means 18 by a pressing mechanism (not shown). A bias having a polarity opposite to that of the next transfer image is applied, and the primary transfer image formed on the image transfer / conveying unit 18 is secondarily transferred onto 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 unit 15 arranged facing the roller 13, and the image transfer conveying unit 18 is After being refreshed, 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 a conventionally known or well-known technique can be replaced or added as necessary. For example, in the present embodiment, as the latent image forming means, the exposing means for deflecting and scanning the laser beam from each laser light source using one polygon mirror onto each image carrier has been described, but the present invention is not limited to this. Exposure means having a polygon mirror corresponding to each image carrier, LED
It is of course applicable to a means for forming a latent image by selectively irradiating light by selectively arranging a plurality of elements or EL elements in a line and further, a writing electrode having the same shape as a latent image type without a scanning optical system. It is needless to say that the invention can be similarly applied to the latent image forming means in which the parts are arranged in a multi-connected manner and slid on the image carrier, and the voltage can be selectively applied to the electrode parts. . The image transfer / conveyance unit is defined as an intermediate transfer belt and a paper conveyance belt.

[0048]

As is apparent from the above description, according to the present invention, the image forming apparatus main body is detachably mounted, the driven gear is driven through the drive gear of the main body, and the toner is supplied to the developing roller. In the image forming apparatus equipped with a developing cartridge for developing the latent image formed on the image carrier by the developing roller and an image carrier for carrying and carrying the toner image, the meshing point of the driving gear and the driven gear Since the developing roller has a rotation fulcrum disposed in the vicinity thereof and is rotatably supported by the main body, and the developing roller is rotationally biased toward the image carrier by the biasing means of the main body, the drive gear Cancels the driving reaction force that occurs when the driven gear is driven, and suppresses the influence of the driving gear, which causes rotational jitter of the developing roller or image carrier due to factors such as gear driving vibrations, resulting in image defects. That it can be prevented.

The rotation fulcrum is disposed in the vicinity of the position for supporting the own weight of the developing cartridge, and has a supply roller for supplying the toner to the developing roller. The rotation fulcrum supports at least the own weight of the developing roller and the supply roller. Since it is arranged near the position, it is possible to prevent the turning biasing force from being affected by the moment due to its own weight. The developing roller has a contact roller that is attached to a part of the developing roller and abuts on the image carrier to be driven to rotate and forms a basis of the relative positional relationship between the roller and the image carrier. Is arranged in the vicinity of the action direction of the reaction force generated when the roller comes into contact with the image carrier and is driven, and in the vicinity of the position supporting the weight of the developing cartridge.
It is possible to stably maintain the rotationally biased state in the direction of the image carrier, and to stably maintain the contact state of the contact roller that contacts the image carrier, and to rotate the image carrier with less rotation jitter. It will be possible.

The rotation fulcrum is supported so as to face the developing cartridge mounting and demounting direction, and is arranged in the vicinity of a position where the force acting when the driven gear is driven from the driving gear acts in the supporting direction. The developing cartridge has a guide means, which is paired with the rotation fulcrum, in the attaching / detaching direction, and the guide means is
The driven gear is supported by a clearance provided in a direction in which the developing cartridge is rotationally biased by the biasing means, and the driven gear is arranged in the vicinity of a position orthogonal to the attaching / detaching direction of the developing cartridge with respect to the driving gear. Since it has a locking means that is locked at a predetermined position of the main body in a state of being rotationally biased by, the supporting state of the developing cartridge can be stabilized and the relative positional relationship of the image carrier can be maintained in a preferable relationship. You can
It becomes easy to attach and detach the developing cartridge.

As described above, according to the present invention, when the mounting state of the developing cartridge is stabilized, the driving reaction force due to the driving of the driving gear and the driving of the developing roller or the contact roller and the image carrier are driven. The influence of the reaction force of the developing roller and the contact roller can be prevented from becoming unstable, and the rotation jitter of the developing roller or the image carrier occurs except the driving vibration factor of the gear. As a result, image defects can be prevented and the image quality can be improved.

[Brief description of drawings]

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

FIG. 2 is a side view from a driving gear side and a driven gear side.

FIG. 3 is a diagram for explaining a mounting portion and rotation of a developing cartridge.

FIG. 4 is a diagram showing the presence and absence of contact rollers that form the basis of the relative positional relationship between the developing roller and the image bearing member, and their configuration examples.

FIG. 5 is an oblique external view showing an embodiment of the developing cartridge according to the present invention.

FIG. 6 is an oblique external view of the developing cartridge shown in FIG. 5 viewed from the opposite side.

FIG. 7 is a diagram showing a state in which a plurality of developing cartridges are arranged in parallel.

FIG. 8 is a schematic cross-sectional view of the overall configuration showing an embodiment of a color image forming apparatus equipped with a plurality of developing cartridges.

[Explanation of symbols]

Reference numeral 17 ... Image carrier, 20 ... Developing cartridge, 31 ... Supply roller, 33 ... Developing roller, 52 ... Developing device mounting guide pin, 51 ... Rotating fulcrum shaft of developing device, 53 ... Developing device supporting member, 54 ... Drive gear, 55 ... Driven gear, 56 ... Energizing spring, 57 ... Contact roller, 59 ... Detachable handle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yujiro Nomura             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F-term (reference) 2H071 BA03 BA13 BA15 BA19 BA20                       BA27 CA05 DA02 DA08 DA09                       DA15 DA22 DA23 EA18                 2H077 AB03 AB13 AC04 AD06 AD13                       AE02 AE03 BA03 BA07 BA08                       BA09 GA13

Claims (10)

[Claims] 1. A latent image formed on an image carrier by a developing roller which is configured to be attachable to and detachable from a main body of an image forming apparatus, a driven gear is driven through a driving gear of the main body, and toner is supplied to a developing roller. In a developing cartridge for developing an image, the developing cartridge has a rotation fulcrum which is disposed near a meshing point of the driving gear and a driven gear and is rotatably supported by the main body, and the developing means is provided by an urging means of the main body. A developing cartridge, wherein a roller is configured to be biased to rotate in the direction of the image carrier. 2. An apparatus comprising: an image carrier for carrying and carrying a toner image; and a developing cartridge for supplying toner to a developing roller to develop the latent image formed on the image carrier by the developing roller. In an image forming apparatus configured to drive a driven gear of the developing cartridge through a driving gear, the developing cartridge has a rotation fulcrum rotatably supported by the main body, and the main body is the developing unit. The developing roller has an urging unit that urges the developing roller to rotate in the direction of the image carrier, and the rotation fulcrum is disposed in the vicinity of a meshing point between the driving gear and the driven gear. The image forming apparatus is configured to be detachable from the main body. 3. The developing cartridge according to claim 1, or the image forming apparatus according to claim 2, wherein the rotation fulcrum is disposed in the vicinity of a position for supporting the weight of the developing cartridge. 4. A supply roller that supplies toner to the developing roller, wherein the rotation fulcrum is disposed at least near a position that supports the weight of the developing roller and the supply roller. The developing cartridge according to claim 2 or the image forming apparatus according to claim 2. 5. A contact roller, which is attached to a part of the developing roller, abuts against the image carrier and is driven to rotate, and forms a basis of a relative positional relationship between the roller and the image carrier. 2. The developing cartridge according to claim 1, wherein the rotation fulcrum is arranged in the vicinity of the acting direction of a reaction force generated when the contact roller abuts on and follows the image carrier. The image forming apparatus described. 6. The rotation fulcrum is arranged in the vicinity of a position for supporting the weight of the developing cartridge and in the vicinity of a direction in which a reaction force generated when the contact roller abuts on the image carrier and is driven thereby. The developing cartridge or the image forming apparatus according to claim 5, wherein. 7. The rotation fulcrum is supported in opposition to the mounting and demounting direction of the developing cartridge, and near the position where a force acting when the driven gear is driven from the driving gear acts in the supporting direction. The developing cartridge according to claim 1, or the image forming apparatus according to claim 2, wherein the developing cartridge is disposed. 8. The developing cartridge has guide means in the attaching / detaching direction which is paired with the rotation fulcrum, and the guide means is provided with a clearance in a direction in which it is rotationally biased by the biasing means. The developing cartridge according to claim 1, or the image forming apparatus according to claim 2, which is supported. 9. The developing cartridge according to claim 1, or the image according to claim 2, wherein the driven gear is arranged in the vicinity of a position orthogonal to the attaching / detaching direction of the developing cartridge with respect to the driving gear. Forming equipment. 10. The developing cartridge has locking means for locking the developing cartridge at a predetermined position of the main body while being rotationally biased by the biasing means.
The developing cartridge according to claim 2 or the image forming apparatus according to claim 2.