JP2003167431A - Developing unit and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To steadily obtain a high quality image by stabilizing the contact of an image carrier with a developing means. <P>SOLUTION: The developing unit is supported by a housing main body (2), rotates on the rotating fulcrums (72 and 73) of both its ends, and is brought into contact with the image carrier (17) and separated therefrom. In the developing unit, the rotating fulcrums of the developing unit are vertically below a developer carrier (33) or a developer supply member (31), as viewed in a projection plane in the direction of the rotational shaft of the developing unit. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device having an improved drive transmission system for an image carrier and an image forming apparatus using the same.

[0002]

2. Description of the Related Art As the image forming apparatus, a 4-cycle type and a tandem type are known. The tandem type image forming apparatus is roughly classified and a plurality of image forming stations are arranged in a row.
The recording paper is electrostatically attracted to the conveyor belt, and the recording paper is sequentially brought into contact with each station while being conveyed, and electrostatic transfer force is applied between the station and the recording paper to record a toner image of a plurality of colors. A paper transport method that overlays colors while directly transferring to paper, and multiple image forming stations are arranged in rows.
While the intermediate transfer belt made of a dielectric material is brought into contact with each station and conveyed, the toner image formed at each station is sequentially primary-transferred by applying electrostatic transfer force between the station and the intermediate transfer belt. Two types of methods are adopted: an intermediate transfer method in which the colors are superimposed on the intermediate transfer belt, and the secondary transfer is performed collectively from the intermediate transfer belt to the recording paper.

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

On the other hand, when categorized by the arrangement method of each image forming station, there are a method of arranging each station in a horizontal direction and a method of arranging each station in a vertical direction (for example, Japanese Patent Laid-Open No. 9-281769). 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 Application Laid-Open No. 8-305115, a method of arranging the image forming stations in an oblique direction is known.

[0006]

However, regardless of whether the image forming stations are arranged vertically or diagonally, the contact state between the image carrier and the developing means is stable. Is important. If the contact state between the image carrier and the developing means is unstable, rotational jitter or the like occurs on the image carrier, and a high quality image cannot be stably obtained.

[0007]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems and to stabilize the contact state between the image carrier and the developing means so that a high quality image can be stably obtained. The purpose is to do. Therefore, the invention of claim 1 is a developing device which is supported by a housing main body and rotates on both ends of a rotation fulcrum so as to move closer to and away from an image carrier. In this case, the rotation fulcrum of the developing device is positioned vertically below the developer carrier or the developer supply member. According to a second aspect of the present invention, the developing device is driven via a driven member that meshes with a driving member fixed to the housing body, and when viewed on a projection plane in the rotation axis direction of the developing device, the developing device and the driven member are driven. It is characterized in that the meshing portion of the member overlaps with the rotation fulcrum or is in the vicinity of the rotation fulcrum. According to a third aspect of the present invention, contact members that contact the image carrier to define the relative positional relationship are provided at both ends of the developing device.
The rotation fulcrum is arranged in the tangential direction of the contact portion between the contact member and the image carrier or in the vicinity thereof when viewed on the projection plane in the rotation axis direction of the developing device. Also,
According to a fourth aspect of the present invention, the rotation fulcrum member forming the rotation fulcrum is supported by a mounting groove formed in the housing body so as to face the mounting groove, and the driven member is a driving member fixed to the housing body. It is characterized in that the acting force generated when driven opposes the supporting direction in the mounting groove.
Further, according to the invention of claim 5, a rotation fulcrum member forming a rotation fulcrum is detachably mounted in a mounting groove formed in the housing body, supported by the bottom of the mounting groove, and fixed to the housing body. It is characterized in that the tangential direction of the meshing portion between the member and the driven member is the direction of attachment / detachment to / from the mounting groove or the vicinity thereof. According to a sixth aspect of the present invention, a rotation fulcrum member that forms a rotation fulcrum is detachably mounted in a mounting groove formed in the housing body, supported by the bottom of the mounting groove, and fixed to the housing body. The member and the driven member are arranged in a direction orthogonal to the attachment / detachment direction of the attachment groove or in the vicinity thereof. According to a seventh aspect of the present invention, a rotation fulcrum member that forms a rotation fulcrum provided at both ends of the developing device and a guide member are detachably mounted in a mounting groove formed in the housing body, and the driving member is driven. The rotation fulcrum member on the side is rotatably supported by the bottom of the mounting groove in a direction orthogonal to the mounting / detaching direction of the mounting groove, and the rotation fulcrum member on the non-drive side is provided with a clearance in a direction orthogonal to the mounting / detaching direction of the mounting groove. And is supported on the bottom of the mounting groove. The invention of claim 8 is the image forming apparatus, wherein the latent image on the image carrier is developed by using the developing device having the above-mentioned configuration.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic cross-sectional view showing an overall configuration of an embodiment of an intermediate transfer type image forming apparatus to which a developing device of the present invention is applied, FIG. 2 is an enlarged view of an image forming unit, and FIG. FIG. 4 is a schematic sectional view showing a state in which the member is opened, and FIG. 4 is a schematic sectional view showing a state in which the rotating portion is opened. In addition, about the same structure between each drawing, the same number may be attached | subjected and description may be abbreviate | omitted.

In FIG. 1, an image forming apparatus 1 of this embodiment is formed on a housing body 2, an opening / closing member (door body) 3 mounted on the front surface of the housing body 2 so as to be openable and closable, and an upper portion of the opening / closing member 3. And a discharge unit (sheet discharge unit) 3a that is formed, and a cooling unit including a control unit 4, a power supply unit 5, an exposure unit (exposure unit) 6, an image forming unit 7, and a blower fan in the housing body 2. 8, a transfer belt unit 9 and a paper feeding unit 10 are arranged, and a paper conveying means 11 is arranged in the opening / closing member 3. The consumables in the image forming unit 7 and the paper feeding unit 10 are configured to be attachable to and detachable from the main body. In that case, the configuration including the transfer belt unit 9 can be removed for repair or replacement. It has become.

The transfer belt unit 9 is rotationally driven by a drive source (not shown), and is provided with a drive roller 12 disposed below the housing main body 2, a driven roller 13 disposed obliquely above the drive roller 12, and An intermediate transfer belt 14 stretched between two rollers and driven to circulate in the direction of the arrow (counterclockwise in the figure);
And the driven roller 13 is not on the vertical line of the drive roller 12, and the housing main body 2 is more than the drive roller 12 when viewed from the opening / closing member 3 side.
It is located at a position displaced to the back side of the
The intermediate transfer belt 14 is arranged so as to be inclined. As a result, when the intermediate transfer belt 14 is driven, the belt surface 14a in which the belt conveying direction X faces downward is located below, and the belt surface 14b in which the conveying direction faces upward is located above. In the present embodiment, the belt surface 14a is a belt tension surface (a surface pulled by the driving roller 12) when the belt is driven, and the belt surface 14b is a belt slack surface when the belt is driven.

The drive roller 12 also serves as a backup roller for a secondary transfer roller 39 described later. A rubber layer 12a (see FIG. 2) having a thickness of about 3 mm and a volume resistivity of 10 ⁵ Ω · cm or less is formed on the peripheral surface of the drive roller 12, and is grounded via a metal shaft. As a result, it serves as a conductive path for the secondary transfer bias supplied through the secondary transfer roller 39. In this way the driving roller 1
By providing the rubber layer 12a having high friction and shock absorption property on 2, it is difficult for the shock when the recording medium enters the secondary transfer portion to be transmitted to the intermediate transfer belt 14, and deterioration of image quality can be prevented. .

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

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

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

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

The image forming stations Y, M,
The C and K image carriers 17 are brought into contact with the belt surface 14a of the intermediate transfer belt 14 which faces downward in the conveying direction, and as a result, the image forming stations Y, M, C, and K are also connected to the intermediate transfer belt 14. Similarly, it is arranged to be inclined.
The image carrier 17 is rotationally driven in the conveyance direction of the intermediate transfer belt 14, as shown by the arrow in the figure. It should be noted that the inclination direction of the intermediate transfer belt 14 may be leftward when the case shown in the drawing is rightward, in which case the belt conveying direction X is the opposite direction and the belt surface facing downward in the conveying direction 14b.
Becomes

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

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

The exposing means 6 is arranged in a space formed obliquely below the image forming unit 7 arranged obliquely, and the control unit 4 and the power supply unit 5 are arranged in the space above the exposing means 6. Has been done. Further, a paper feeding unit 10 is arranged at the bottom of the housing body 2 below the exposure means 6. Control unit 4 and power supply unit 5
Is disposed adjacent to the exposure means 6, so that the installation space can be made smaller than in the case where these are arranged in parallel with the frame that supports the device components.

The exposing means 6 has a case 18, which is arranged in a space formed obliquely below the belt surface 14a facing downward in the conveying direction, and the inclined surface 1 of the case 18 is provided.
8a is parallel to the belt surface 14a. Case 18
A single scanner means 21 including a polygon mirror motor 21a and a polygon mirror 21b is provided at the bottom of the, and a single f-θ lens 22 and a reflection mirror 23 are provided, and further a reflection mirror 23 is provided. Above the scanning optical paths y, m, c, k of the respective colors so that the scanning optical paths y, m, c, k are parallel to the inclined surface 18a (belt surface 14a).
The four folding mirrors 24 are arranged on the scanning optical path k, and the scanning optical paths y, m, c, and k reflected by the folding mirror 24 are arranged on the scanning optical paths m, c, and k so that the scanning optical paths m, c, and k are irradiated. Two folding mirrors 25 are arranged. By providing the folding mirrors 24 and 25 in this manner, the scanning optical paths y, m, c, and k can be bent, and the height of the case 18 can be reduced, thereby achieving compactness. In addition,
Image carrier 17 of each image forming station Y, M, C, K
The folding mirrors 24 and 25 are arranged so that the scanning optical path lengths to the same are the same.

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

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

A cooling means 8 comprising a blower fan is provided on the side surface of the housing main body 2, and the outside air is introduced in the direction of the arrow shown in the figure to cool the exposure means 6, the control unit 4 and the power supply unit 5. . Air introduced into the apparatus from the rear of the recording sheet P in the conveyance direction or the width direction of the recording sheet P in the conveyance direction is guided to the vicinity of the polygon motor 21a, further guided to the control unit 4 and the power supply unit 5, and then outside the apparatus. Since the cooling passage is formed, the temperature rise of the polygon motor 21a is suppressed, image quality deterioration is prevented, and the life of the polygon motor 21a is extended.

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

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

The image carrier 17 is rotated in the conveying direction of the intermediate transfer belt 14, and the supply roller 31 and the developing roller 33 are used.
Is driven to rotate in the direction opposite to the rotation direction of the image carrier 17, as shown by the arrow in the figure. Therefore, at the contact portion between the supply roller 31 and the developing roller 33, the peripheral surfaces move in opposite directions and rub against each other, and at the contact portion (developing nip portion), the developing roller 33 and the image carrier 17 contact at the peripheral surface. Move in the same direction.
On the other hand, the stirring member 29 is rotationally driven in the direction opposite to the rotation 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 to a coating layer having a predetermined thickness by the regulating blade 34, and the thinned toner layer is conveyed to the image carrier 17 so that the developing roller 33 and the image carrier 17 are in order. The latent image portion of the image carrier 17 is developed in the nip portion formed by contacting by moving in the direction and in the vicinity thereof.

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.

Returning to FIG. 1, the paper feeding unit 10 comprises a paper feeding cassette 35 in which recording media P are stacked and held, and a pickup roller 36 for feeding the recording media P one by one from the paper feeding cassette 35. It has a paper feed section.

The sheet conveying means 11 is a pair of registration rollers 37 that regulates the timing of feeding the recording medium P to the secondary transfer portion.
A secondary transfer roller 39 as a secondary transfer means that is pressed against the drive roller 12 and the intermediate transfer belt 14, a recording paper conveyance path 38, a fixing means 40, and a discharge roller pair 41.
And a conveyance path 42 for double-sided printing.

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

FIG. 3 shows the housing body 2 to the opening / closing member 3.
Shows the opened state. The opening / closing member 3 is attached to the housing body 2 so as to be openable / closable. In the present embodiment, each unit can be attached / detached by accessing from only the front surface of the device, and the device can be compactly installed indoors. There is. In the opening / closing member 3, a drive motor 61 is arranged, and a rotating lever 63 pivotally supported by a fixed shaft 62 is arranged. One end of the rotating lever 63 is fixed to the shaft of the secondary transfer roller 39, and the other end is fixed to the opening / closing member 3 via a spring 64. Normally, the secondary transfer roller 39 is biased by the spring 64 so that the arrow shown in FIG. The intermediate transfer belt 14 and the driving roller 12
It is possible to press. An eccentric cam 65 is provided on the spring 64 side of the rotating lever 63. The rotating lever 63, the spring 64, and the eccentric cam 65 constitute a separating / contacting means for the secondary transfer roller.

The rotating shaft of the drive motor 61 is connected to the shaft of the fixing roller 40a via a transmission device (not shown) composed of a gear and a clutch, and a transmission device composed of a gear and a clutch (not shown). ) Through the eccentric cam 6
5 is connected to the cam shaft. With this configuration, when the drive motor 61 rotates in the normal direction, the fixing roller 40a is driven, and when the drive motor 61 rotates in the reverse direction, the eccentric cam 65 rotates,
The rotating lever 63 rotates against the spring 64 to move the secondary transfer roller 39 in the direction opposite to the arrow shown in the drawing, and separates from the intermediate transfer belt 14.

According to the present embodiment, the drive motor 61 is disposed not on the housing body 2 side but on the opening / closing member 3 side, so that the fixing means 40 and the drive motor 6 having a heavy drive load are disposed.
The drive engagement of No. 1 is separated and not engaged by the opening / closing operation of the opening / closing member 3, so that unevenness in the conveyance of the recording paper and vibration of the entire apparatus due to poor engagement of the drive system can be prevented and the image quality can be maintained. Further, the drive motor 61 is reversely rotated at a timing when the recording paper is not conveyed, and when the secondary transfer roller 39 is separated from the intermediate transfer belt 14, the density adjustment test image and the color misregistration detection mark are displayed on the intermediate transfer belt 14. It is possible to perform a correction operation in which the secondary transfer roller 39 is formed and read by a sensor, and a separate drive source is not required for the separation / contact operation of the secondary transfer roller 39.

FIG. 4 is a diagram for explaining attachment and replacement of consumables. In the present embodiment, the housing body 2 is provided with a shaft 66, which is a rotation fulcrum, above the shaft 57 of the opening / closing member 3, and the rotation unit 50 including a frame is rotatably mounted on the shaft 66. The transfer belt unit 9 described in FIG. 1 is supported by the rotating portion 50. The image forming unit and the transfer belt unit are exposed when the rotating unit 50 is rotated forward following the opening / closing member 3.
In this state, the developing means 2 supported by the housing body 2
0, image carrier unit (image carrier 17 and charging means 1
The transfer belt unit 9 (including a frame 67a that supports 9) 67 and the transfer belt unit 9 can be removed for repair or replacement. In the present embodiment, after the developing means 20 is attached to the housing body, the rotating portion 50 is rotated to bring the image carrier 17 into contact with the developing roller to position the image carrier 17, so that the developing means is installed at the back of the body. Since the image carrier 17 is brought into contact with the toner after it is placed at a high position, it is possible to prevent dirt due to toner leakage. The image forming unit 7 may be supported by the rotating portion 50.

FIG. 5 is a perspective view of the developing device of the present embodiment, FIG. 6 is a view for explaining the mounting of the developing device, and FIG. 7 is a sectional view of the developing device of the present embodiment when viewed from the side opposite to the driving side. 8 is a sectional view of the developing device of the present embodiment as seen from the driving side, and FIG.
FIG. 6 is a diagram showing a state in which developing devices for M, C, and K are attached.

As shown in FIG. 5, the developing device is provided with mounting plates 70 and 71 at both ends thereof, and rotating pins 72 and 73 which form pivotal fulcrums of the developing device on the mounting plates, respectively.
And the guide pins 74 and 75 are provided so as to project outward. Further, at both ends of the developing roller 33,
A contact roller 77 is provided which is in contact with the end portion of the image carrier and which freely rotates about the developing roller as a support shaft to determine the relative position to the image carrier. The contact roller is used to provide a gap between the developing roller and the image carrier in jumping development, but is also used as a buffer between the developing roller and the image carrier in pressure contact development. Some types do not exist, and the present embodiment is applicable to any type.

On the other hand, as shown in FIG. 6, mounting grooves 2a and 2b for mounting the developing device are provided in the housing main body 2 corresponding to both ends of the developing device, and the rotating pin 72, is provided in this groove. The developing device is mounted by inserting 73 and the guide pins 74 and 75 in the direction indicated by the arrow (removing direction). Figure 6
6A is a mounting groove 2a viewed from a side (driving side) where the developing device is driven by a driving gear supported by the main body, and FIG.
(B) shows the mounting groove 2b as viewed from the side opposite to the driving side, which is opposite to the driving side. On the driving side, the rotating pin 72 is rotatably supported on the bottom of the mounting groove 2a. on the other hand,
The rotating pin 73 on the non-driving side is supported with a clearance provided in a direction orthogonal to the attaching / detaching direction of the groove so that it can be slightly moved. With this configuration, the developing device is supported at three points by the contact between the contact rollers 77 at both ends of the developing roller and the image carrier 17, and the support of the rotating pin 72 at the bottom of the mounting groove, and the rotating pin 74 is slightly supported. Since it is movable within the range, the contact state between the developing device and the image carrier is stabilized.

FIGS. 7 and 8 show a state in which the rotation pin and the guide pin are mounted in the mounting grooves 2a and 2b of the housing body 2, and one end of the developing device is fixed by the biasing spring 2c. Is biased so as to rotate toward the image carrier 17 side with the rotation pins 72 and 73 as fulcrums.
Therefore, in a state where the image carrier 17 is not attached,
The developing device is in a position where the urging spring 2c is extended, and when the image carrier 17 is mounted and pressed against the developing roller and positioned by a lock lever (not shown), the developing device uses the urging spring to move the image. It is positioned while being pressed against the carrier 17. With such a configuration, there is no restriction on the positional relationship with the image carrier when the developing device is attached and detached, and the attachment and detachment operation becomes easy. Further, since the function of configuring the relative position relationship between the developing device and the image carrier is divided into two parts, it is possible to realize a stable relative position structure without undue operation. .

In the developing device of this embodiment, the supply roller 3 is used.
1. The weight of the developing roller 33 is heavy, and the center of gravity of the developing roller 33 is in the vicinity of both rollers when viewed from the projection plane in the rotation axis direction of the roller. Are arranged so that With this configuration, it is possible to eliminate or reduce the rotation moment with respect to the rotation fulcrum (rotation pins 72 and 73) due to the weight of the developing device. In this way, the rotation moment due to its own weight does not affect the contact state of the developing roller and the image carrier, or the contact state of the developing roller itself and the image carrier, so that the contact state of the developing device and the image carrier is Is stable, and the image carrier can be rotationally driven with less rotation jitter, and the image is stabilized. Since the contact state between the developing device and the image bearing member is stabilized in this way, the degree of freedom in selecting the constituent materials of the developing roller and the supply roller is wide, and it is possible to select an aluminum-based material having a relatively low specific gravity as a base. Alternatively, even if the iron-based material having a relatively high specific gravity is used as a base, it does not affect the entire developing device, and it becomes possible to select the cost advantage while ignoring its own weight. It should be noted that it is preferable that the rotational moment acts in the direction of separating the developing roller 33 from the image carrier 17 even when the rotational moment is generated with respect to the rotation fulcrum due to the weight of the developing device.

The developing device is driven by a driving gear 80 attached to the housing body 2 and a driven gear 8 on the developing device side.
The rotation of the driven gear 81 is transmitted to the supply roller 31, the developing roller 33, and the toner stirring member 29 through a gear train that meshes with the driven gear 81. When viewed on the roller rotation axis direction projection surface of the developing device, the position of the meshing portion of the drive gear 80 and the driven gear 81 overlaps with the rotation fulcrum (rotation pins 72, 73) or is at least in the vicinity thereof. To do. As a result, the reaction force generated by driving does not act on the developing device as a rotation moment with respect to the rotation fulcrum, or is suppressed to a small value. With this configuration, the reaction force generated by driving does not give a rotation moment to the rotation fulcrum, so that the rotation jitter of the developing roller or the image carrier is small and a stable image can be obtained. Note that it is desirable that the developing roller 33 is configured to act in a direction away from the image carrier 17 even when a rotational moment is generated.

Similarly, when viewed on the projection plane in the direction of the rotation axis of the developing device, the contact roller 77 is driven by the contact between the contact roller 77 and the image carrier 17, or the contact roller 77 is driven by the image carrier. When the roller is driven to rotate by rubbing against the image carrier, or when the developing roller 33 and the image carrier 17 directly rotate without contact, the image carrier and the contact roller,
Alternatively, in the tangential direction of the contact portion between the image carrier and the developing roller, a driving reaction force is generated in the direction of the solid arrow A in the figure. This reaction force is generated according to the difference in peripheral speeds of the developing roller and the image carrier when the peripheral speeds are different. That is, when the rotation peripheral speed of the developing roller or the abutment roller is faster than the rotation peripheral speed of the image carrier, it occurs in the direction of the solid line arrow in the figure, and conversely, the development roller rotates relative to the rotation peripheral speed of the image carrier. Alternatively, when the rotating peripheral speed of the contact roller is slow, it occurs in the direction opposite to the solid arrow. Therefore, as shown by a solid arrow A in the figure, the direction of the driving reaction force is set to the rotation fulcrum or the rotation fulcrum so that the rotation moment is not generated on the rotation fulcrum (the rotation pins 72 and 73) by the drive reaction force. Make it close to the fulcrum.
With this arrangement, the reaction force generated by the contact with the image carrier does not give a moment about the rotation fulcrum to the developing device, and the rotation of the image carrier becomes unstable due to the driving reaction force. Can be prevented.

The rotary pin 72 on the driving side is attached to the mounting groove 2
It is supported in the mounting direction and in a direction orthogonal to the mounting direction at the bottom of the a. On the other hand, the rotating pin 73 on the opposite drive side
Is supported in the mounting direction in the mounting groove 2b, and in the direction orthogonal to the mounting direction, a clearance is provided that is movable with respect to the driving reaction force generated between the contact roller of the developing roller and the image carrier. ing. Therefore, the developing roller 33
The image carrier 17 and the image bearing member 17 have a so-called three-point contact structure of the drive-side turning pin 72 and the two contact rollers 77, so that the contact state can be stabilized.

In addition, the rotation fulcrum (rotation pins 72, 73)
Is supported by the bottom of the mounting groove in the mounting direction, and the driven gear 81 is driven by the drive gear 80 so that the force acting on the driven gear 81 is the supporting direction of the bottom of the mounting groove (the mounting direction in the groove).
Alternatively, since it acts toward the vicinity thereof, the supporting state of the developing device is stabilized and the relative positional relationship with the image carrier is maintained in a preferable relationship.

Further, the driven gear 81 is arranged at a position orthogonal to the attaching / detaching direction of the developing device with respect to the driving gear 80 (the direction of the arrow parallel to the mounting groove in FIGS. 7 and 8) or in the vicinity thereof. At this time, the direction in which the driven gear 81 meshes with the drive gear 80 is the direction of the mounting groove, so that when the developing device is attached or detached, the driven gear 81 can be meshed with or disengaged from the drive gear 80 without difficulty. As a result, it is not necessary to additionally provide an auxiliary mechanism for the purpose of stabilizing engagement and disengagement.

Further, in the present embodiment, as shown in FIG. 4, it is possible to rotate the rotating portion 50 to remove the image carrier, and to attach and detach the developing device in that state.
First, the developing device 20 is attached to the main body of the apparatus, and then the rotating unit 5
By rotating 0, the image carrier 17 is pressed and pressed against the developing device, and the position of the image carrier can be determined by the lock lever to position the developing position. In this way, the developing device is first set in a place where the main body of the device does not move easily, the image carrier is pressed and positioned from above, and the intermediate transfer belt is provided from above, so that the developing device can be attached or removed It is possible to prevent toner stains on other parts.

Further, the developing device is inserted in the direction of gravity (the direction of the mounting groove) in the direction of gravity, and the developing device is inserted in the direction opposite to the direction of contact with the image carrier, and the direction of gravity is relative to the image carrier. The direction of separating the developing device reduces the contact pressure with the image carrier, which has a favorable effect on the contact between the developing device and the image carrier.

Further, as shown in FIG. 9, the space between the mounting plates 70 at both ends of the developing device 17 is an empty space into which the head of the adjacent developing device can be inserted, and therefore the rotating pin is provided. The positions of 72 and 73 overlap with the adjacent developing device. In this way, since the rotation fulcrum can be arranged so as to overlap the adjacent developing device, space saving can be achieved.

In the above embodiment, the rotation fulcrum is provided on the lower side of the developing device. However, the rotation fulcrum is provided on the upper side of the developing device so that no rotation moment is generated with respect to the rotation fulcrum. You may do it.

[0050]

As described above, according to the present invention, when the developing device is rotated at the rotation fulcrums at both ends to move the developing device closer to and away from the image carrier, the rotational moment due to the weight of the developing device is Since the contact state between the developing device and the image carrier is not affected, the contact state between the developing device and the image carrier is stable, and the image carrier can be rotationally driven with less rotational jitter and the image is stabilized. . Further, the degree of freedom in selecting the constituent material of the developing device can be widened. Further, since the reaction force generated by the meshing of the driving member and the driven member of the developing device does not give the rotation moment to the rotation fulcrum, the rotation jitter of the developing roller and the image carrier is small, and a stable image is obtained. be able to. Further, since the driving reaction force generated according to the rotational peripheral speed difference between the developing device and the image carrier does not generate a rotation moment with respect to the rotation fulcrum, the rotation of the image carrier is caused by the driving reaction force. Instability can be prevented.
Further, since the developing device and the image carrier have a three-point contact structure, the contact state can be stabilized against the driving reaction force generated by the contact between the developing device and the image carrier. Further, the rotation fulcrum is supported at the bottom of the mounting groove so as to face in the mounting direction, the supporting state of the developing device is stabilized, and the relative positional relationship with the image carrier is maintained in a preferable relationship. Further, since the driven member has a positional relationship with the drive member orthogonal to the attaching / detaching direction of the developing device, the developing device can be easily attached / detached, and it is necessary to separately provide an auxiliary mechanism for the purpose of stabilizing engagement and disengagement. Absent.

[Brief description of drawings]

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

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

FIG. 3 is a schematic cross-sectional view showing a state in which an opening / closing member is opened.

FIG. 4 is a diagram illustrating attachment and replacement of consumables.

FIG. 5 is a perspective view of the developing device of the present embodiment.

FIG. 6 is a diagram illustrating mounting of a developing device.

FIG. 7 is a sectional view of the developing device as viewed from the side opposite to the driving side.

FIG. 8 is a sectional view of the developing device as viewed from the driving side.

FIG. 9 is a view showing a mounting state of Y, M, C, and K developing devices.

[Explanation of symbols]

2 ... Housing body, 2a, 2b ... Mounting groove, 2c ... Energizing spring, 17 ... Image carrier, 20 ... Developing means, 31 ... Supply roller, 33 ... Developing roller, 70, 71 ... Mounting plate, 7
2, 73 ... Rotation pin (rotation fulcrum), 74, 75 ... Guide pin, 77 ... Contact roller, 80 ... Drive gear, 81 ... Driven gear

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yujiro Nomura             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F-term (reference) 2H077 AD06 BA01 BA07 BA08 BA09                       GA13

Claims (8)

[Claims] 1. A developing device which is supported by a housing main body and rotates at pivotal fulcrums at both ends to move closer to and away from an image carrier, when viewed on a projection plane in a rotation axis direction of the developing device.
A developing device, wherein a fulcrum of rotation of the developing device is positioned vertically below a developer carrier or a developer supplying member. 2. The developing device is driven via a driven member that meshes with a driving member fixed to the housing body,
2. The developing device according to claim 1, wherein the meshing portion of the driving member and the driven member overlaps with the rotation fulcrum or is in the vicinity of the rotation fulcrum when viewed on a projection plane in the rotation axis direction of the development device. . 3. A contact member that abuts on the image carrier to define a relative positional relationship is provided at both ends of the developing device, and the rotation fulcrum, when viewed on a projection plane in the rotation axis direction of the developing device, 3. The contact member is arranged in the tangential direction of the contact portion between the contact member and the image carrier, or in the vicinity thereof.
Described developing device 4. A rotation fulcrum member forming a rotation fulcrum is supported in a mounting groove formed in the housing body so as to face the mounting direction, and the driven member is driven by a driving member fixed to the housing body. 2. The acting force generated when the mounting groove faces the supporting direction in the mounting groove.
4. The developing device according to any one of 3 to 3. 5. A rotation fulcrum member that forms a rotation fulcrum is detachably mounted in a mounting groove formed in the housing body, supported by the bottom of the mounting groove, and a driving member fixed to the housing body and a driven member. 5. The developing device according to claim 1, wherein the tangential direction of the meshing portion of the member is the direction of attachment / detachment to / from the mounting groove or the vicinity thereof. 6. A rotation fulcrum member forming a rotation fulcrum is detachably mounted in a mounting groove formed in the housing body and supported by a bottom portion of the mounting groove, and a driving member fixed to the housing body and a driven member. 6. The developing device according to claim 1, wherein the member is arranged in a direction orthogonal to the attaching / detaching direction of the mounting groove or in the vicinity thereof. 7. A rotation fulcrum member that forms a rotation fulcrum provided at both ends of the developing device and a guide member are detachably mounted in a mounting groove formed in the housing body.
The rotation fulcrum member on the drive side is rotatably supported by the bottom of the attachment groove in a direction orthogonal to the attaching / detaching direction of the attachment groove, and the rotation fulcrum member on the non-drive side has a clearance in a direction orthogonal to the attaching / detaching direction of the attachment groove. 7. The developing device according to claim 1, wherein the developing device is supported by the bottom of the mounting groove. 8. An image forming apparatus which develops a latent image on an image carrier by using the developing device according to claim 1.