JP4058600B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus in which a detachable developing device is positioned by an image carrier.
[0002]
[Prior art]
As the image forming apparatus, a 4-cycle type or a tandem type is known, and the tandem type image forming apparatus is roughly classified.
(1) A plurality of image forming stations are arranged in a line, the recording paper is electrostatically adsorbed to the transport belt, and the recording paper is sequentially brought into contact with each station and transported between the stations and the recording paper. A paper transport system that applies color transfer while applying electrostatic transfer force to a toner image of multiple colors directly onto a recording paper; and
(2) A plurality of image forming stations are arranged in a line, and an intermediate transfer belt formed of a dielectric is brought into contact with each station and conveyed, and the toner image formed at each station is transferred to the station. An intermediate transfer method in which an electrostatic transfer force is applied between the belts to sequentially perform primary transfer, color superimposition on the intermediate transfer belt, and secondary transfer collectively from the intermediate transfer belt to the recording paper;
The following two methods are adopted.
[0003]
The above paper transport method requires means (rollers and brushes) for adsorbing the recording paper to the transport belt and a high voltage power supply, but the intermediate transfer method does not require these means and power supply, and the paper transport method. However, it is necessary to strictly control the transfer bias applied to each image transfer unit according to the size, thickness, and type of the recording paper.In the intermediate transfer method, the resistance and thickness are independent of these factors of the recording paper. Transfer conditions such as transfer voltage, transfer current, and contact pressure are only performed when a primary transfer of a toner image is performed on an intermediate transfer belt with a constant surface roughness, and then secondary transfer is performed collectively on a recording sheet. Therefore, the intermediate transfer method has many advantages.
[0004]
On the other hand, according to the arrangement method of each image forming station, there are a method in which each station is arranged in the horizontal direction and a method in which each station is arranged in the vertical direction (for example, JP-A-9-281769). The latter has the disadvantage that the height of the device is high and it is difficult to install on the desk.
[0005]
For this purpose, conventionally, Japanese Patent Application Laid-Open No. 11-95520 and Japanese Patent Application Laid-Open No. 8-305115 have known a method in which image forming stations are arranged in an oblique direction.
[0006]
[Problems to be solved by the invention]
However, it is important that the contact state between the image carrier and the developing means is stable regardless of whether the image forming stations are arranged vertically or obliquely. If the contact state between the image carrier and the developing means is unstable, rotational jitter or the like occurs in the image carrier, and a high quality image cannot be obtained stably. In addition, it is important that replacement and positioning of the developing means and the image carrier are easy and measures against developer spillage can be taken.
[0007]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and it is easy to replace and position a developing means and an image carrier and to take measures against developer spillage.
The present invention has a detachable developing device, and when the image carrier is displaced to the operating position, the developing device is positioned by the image carrier, and the image carrier is rotationally displaced with respect to the apparatus main body. In an image forming apparatus that is possible,
The developing device forms a rotation fulcrum provided at both ends of a vertically lower portion. Rotating pin and guide pin The drive-side rotation pin, which is detachably mounted in the mounting groove formed in the apparatus main body and the developing device is driven by the driving device, is supported in the mounting groove bottom and in the direction orthogonal to the mounting direction. The rotation pin opposite to the drive side is supported in the mounting direction at the bottom of the mounting groove, and is supported with a clearance provided in a direction orthogonal to the mounting direction.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 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 cross-sectional view showing a state in which the rotating part is opened. In addition, about the same structure between each drawing, the same number may be attached | subjected and description may be abbreviate | omitted.
[0009]
In FIG. 1, an image forming apparatus 1 according to the present embodiment includes a housing body 2, an opening / closing member (door body) 3 that is openably / closably attached to the front surface of the housing body 2, and an exhaust formed on an upper portion of the opening / closing member 3. The housing body 2 has a control unit 4, a power supply unit 5, an exposure unit (exposure unit) 6, an image forming unit 7, a cooling unit 8 including a blower fan, and a transfer unit. A belt unit 9 and a paper feed unit 10 are disposed, and a paper transport unit 11 is disposed in the opening / closing member 3. The consumables in the image forming unit 7 and the paper feeding unit 10 are detachable from the main body. In this case, the configuration including the transfer belt unit 9 can be removed and repaired or replaced. It has become.
[0010]
The transfer belt unit 9 is rotationally driven by a drive source (not shown), a drive roller 12 disposed below the housing body 2, a driven roller 13 disposed obliquely above the drive roller 12, and the two An intermediate transfer belt 14 that is stretched between rollers and circulated and driven in the direction of the arrow shown in the figure (counterclockwise in the figure), and a cleaning means 15 that contacts the surface of the intermediate transfer belt 14 are provided. 12, not on the vertical line 12 but at a position shifted from the drive roller 12 to the back side of the housing body 2 when viewed from the opening / closing member 3 side. Therefore, as shown in the figure, the intermediate transfer belt 14 is disposed at an inclination. . As a result, the belt surface 14a in which the belt conveyance direction X when the intermediate transfer belt 14 is driven is positioned downward, and the belt surface 14b in which the conveyance direction is upward is positioned upward. In the present embodiment, the belt surface 14a is a belt tension surface (surface pulled by the drive roller 12) during driving of the belt, and the belt surface 14b is a belt slack surface during belt driving.
[0011]
The drive roller 12 also serves as a backup roller for a secondary transfer roller 39 described later. On the peripheral surface of the drive roller 12, for example, a thickness of about 3 mm and a volume resistivity of 10 ^Five A rubber layer 12a (see FIG. 2) of Ω · cm or less is formed, and as a conductive path of the secondary transfer bias supplied through the secondary transfer roller 39 by grounding through a metal shaft. Yes. Thus, by providing the driving roller 12 with the rubber layer 12a having high friction and shock absorption, it is difficult for the impact when the recording medium enters the secondary transfer portion to be transmitted to the intermediate transfer belt 14, and the image quality is deteriorated. Can be prevented.
[0012]
In the present embodiment, the diameter of the driving roller 12 is smaller than the diameter of the driven roller 13. Thereby, the recording paper after the secondary transfer can be easily peeled by the elastic force of the recording paper itself. Further, the driven roller 13 is also used as a backup roller for the cleaning means 15 described later.
[0013]
The cleaning means 15 is provided on the side of the belt surface 14a facing downward in the transport direction. As shown in FIG. 2, a cleaning blade 15a that removes toner remaining on the surface of the intermediate transfer belt 14 after the secondary transfer and a toner transport member 15b that transports the collected toner are provided. The cleaning blade 15a is driven. The intermediate transfer belt 14 is in contact with the intermediate transfer belt 14 around the roller 13.
[0014]
Further, a primary transfer member 16 made of a leaf spring electrode is brought into contact with the back surface of the intermediate transfer belt 14 by an elastic force so as to face an image carrier 17 of each image forming station Y, M, C, K described later. A transfer bias is applied to the primary transfer member 16.
[0015]
The image forming unit 7 includes a plurality (four in this embodiment) of image forming stations Y (for yellow), M (for magenta), C (for cyan), and K (for black) that form images of different colors. 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 a corona charging unit disposed around the image carrier 17. The charging unit 19 and the developing unit 20 are provided. The order of arrangement of the image forming stations Y, M, C, and K is arbitrary.
[0016]
Then, the image carrier 17 of each image forming station Y, M, C, K is brought into contact with the belt surface 14a facing downward in the transport direction of the intermediate transfer belt 14, and as a result, each image forming station Y, M , C, and K are also inclined and disposed in the same manner as the intermediate transfer belt 14. The image carrier 17 is rotationally driven in the conveyance direction of the intermediate transfer belt 14 as indicated by the arrows in the figure. Note that the inclination direction of the intermediate transfer belt 14 may be inclined to the left when the illustrated case is inclined to the right. In this case, the belt conveyance direction X is the reverse direction, and the belt surface downward in the conveyance direction is 14b. Become.
[0017]
Next, the charging unit 19 will be described in detail using the image forming station C in FIG. 2 as an example. The developing means 20 has a developing roller exposed portion 20 a formed in the vicinity of the developing roller 33, while the corona charging means 19, which is a charging means, has an upward opening 19 a facing the image carrier 17. ing. At this time, when the upward opening 19a of the corona charging unit 19 is positioned below the developing roller exposed portion 20a, toner spills from the developing roller exposed portion 20a due to gravity, and the corona charging unit 19 correlates with the corona charging unit 19 from the upward opening 19a. A problem arises that the corona charging means 19 is contaminated by entering the inside 19.
[0018]
Therefore, in the present embodiment, the upward opening 19a is offset toward the intermediate transfer belt 14 so that the upward opening 19a of the corona charging unit 19 does not overlap the developing roller exposed portion 20a of the developing unit 20. I have to. Accordingly, it is possible to solve the problem that the toner spills from the developing roller exposed portion 20a due to gravity and enters the corona charging means 19 from the upward opening 19a, thereby contaminating the corona charging means 19.
[0019]
The exposure unit 6 is disposed in a space formed obliquely below the image forming unit 7 disposed in the oblique direction, and the control unit 4 and the power supply unit 5 are disposed in the space above the exposure unit 6. . A paper feeding unit 10 is disposed below the exposure unit 6 and at the bottom of the housing body 2. Since the control unit 4 and the power supply unit 5 are disposed adjacent to the exposure means 6, the installation space can be reduced as compared with the case where they are disposed in parallel with the frame that supports the apparatus components.
[0020]
Further, the exposure means 6 has a case 18, and the case 18 is disposed in a space formed obliquely below the belt surface 14a facing downward in the transport direction, and the inclined surface 18a of the case 18 is made parallel to the belt surface 14a. ing. A single scanner means 21 comprising a polygon mirror motor 21a and a polygon mirror 21b is disposed at the bottom of the case 18, and a single f-θ lens 22 and a reflection mirror 23 are disposed. Above the mirror 23, four folding mirrors 24 are arranged in the scanning light paths y, m, c, k so that the scanning light paths y, m, c, k of each color are parallel to the inclined surface 18a (belt surface 14a). Further, three folding mirrors 25 are arranged in the scanning light paths m, c, k so that the scanning optical paths y, m, c, k reflected by the folding mirror 24 are irradiated to the image carrier 17. Yes. By providing the folding mirrors 24 and 25 in this way, the scanning light paths y, m, c, and k can be bent, and the height of the case 18 can be reduced, thereby achieving a compact size. The folding mirrors 24 and 25 are arranged so that the scanning optical path lengths to the image carrier 17 of the image forming stations Y, M, C, and K are the same.
[0021]
In the exposure means 6 having the above configuration, image signal light corresponding to each color is emitted from the polygon mirror 21b after being modulated and formed based on a common data clock frequency, and the f-θ lens 22, the reflection mirror 23, and the folding mirror. Through 24 and 25, the image carrier 17 of each image forming station Y, M, C, K is irradiated to form a latent image.
[0022]
In this embodiment, by arranging the scanning optical system below the apparatus, it is possible to minimize the vibration of the scanning optical system due to the vibration that the drive system of the image forming unit gives to the frame that supports the apparatus. Deterioration can be prevented. In particular, by arranging the scanner means 21 at the bottom of the case 18, the vibration that the polygon motor 21a itself gives to the entire case 18 can be minimized, and deterioration of image quality can be prevented. Further, the vibration applied to the entire case 18 can be minimized by using one polygon motor 21a as a vibration source.
[0023]
Cooling means 8 comprising a blower fan is provided on the side surface of the housing body 2, and outside air is introduced in the direction of the arrow in the figure to cool the exposure means 6, the control unit 4 and the power supply unit 5. The air taken into the apparatus from behind the recording paper P in the conveyance direction or from the width direction in the conveyance direction of the recording paper P is guided to the vicinity of the polygon motor 21a, and further guided to the control unit 4 and the power supply unit 5 and then outside the apparatus. Since the leading cooling passage is formed, an increase in temperature of the polygon motor 21a is suppressed to prevent image quality deterioration and extend the life of the polygon motor 21a.
[0024]
Next, details of the developing unit 20 will be described on behalf of the image forming station Y in FIG. In the present embodiment, the image stations Y, M, C, and K are inclined and the image carrier 17 is brought into contact with the belt surface 14a facing downward in the conveyance direction of the intermediate transfer belt 14, so that The toner storage container 26 is disposed obliquely downward. Therefore, a special configuration is adopted for the developing means 20.
[0025]
That is, the developing unit 20 includes a toner storage container 26 that stores toner (hatched portion in the drawing), a toner storage section 27 formed in the toner storage container 26, and a toner disposed in the toner storage section 27. The stirring member 29, the partition member 30 partitioned on the upper part of the toner storage portion 27, the toner supply roller 31 disposed above the partition member 30, and the toner supply roller 31 provided on the partition member 30 The developing blade 33 is configured to be in contact with the toner supply roller 31 and the image carrier 17, and the regulating blade 34 is in contact with the developing roller 33.
[0026]
The image carrier 17 is rotated in the conveyance direction of the intermediate transfer belt 14, and the supply roller 31 and the developing roller 33 are driven to rotate in the direction opposite to the rotation direction of the image carrier 17 as shown by the arrows in the figure. Accordingly, the peripheral surfaces of the supply roller 31 and the developing roller 33 move in the opposite directions and rub against each other at the contact portion, and the developing roller 33 and the image carrier 17 have the peripheral surfaces at the contact portion (development nip portion). Move in the same direction. On the other hand, the stirring member 29 is driven to rotate 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 reservoir 27 is supplied to the toner supply roller 31 along the upper surface of the partition member 30, and the supplied toner is supplied by being rubbed with the flexible blade 32. The roller 31 is supplied to the surface of the developing roller 33 by the mechanical adhesion force on the surface irregularities and the adhesion force due to the frictional band power. 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, and the developing roller 33 and the image carrier 17 are sequentially moved. The latent image portion of the image carrier 17 is developed in the vicinity of the nip portion formed in contact with the direction movement and in the vicinity thereof.
[0027]
In this 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 unit 27. With this configuration, it is possible to prevent fluctuations in the contact pressure of the regulating blade 34 against the developing roller 33 due to a decrease in the stored toner, and surplus toner scraped off from the developing roller 33 by the regulating blade 34 falls into the toner reservoir 27. Therefore, filming of the developing roller 33 can be prevented.
[0028]
Further, the contact portion between the developing roller 33 and the regulating blade 34 is positioned below the contact position between the supply roller 31 and the developing roller 33, and the surplus that has been supplied to the developing roller 33 by the supply roller 31 and has not shifted to the developing roller 33. A path is provided for returning the toner and excess toner regulated and removed from the developing roller 33 by the regulating blade 34 to the toner reservoir 27 below the developing means. The toner returning to the toner reservoir 27 is contained in the toner reservoir 27 by the stirring member 29. The toner is agitated and supplied again to the toner introduction portion near the supply roller 31 by the agitating member 29. Therefore, the excess toner is dropped to the lower part without being jammed on the sliding part of the supply roller 31 and the developing roller 33 or the contact part of the developing roller 33 and the regulating blade 34, and the toner in the toner storing part 27 is stirred. It is possible to prevent the toner in the developing unit from gradually deteriorating and a sudden change in image quality occurring immediately after the replacement of the developing unit.
[0029]
Returning to FIG. 1, the paper feed unit 10 is a paper feed unit including a paper feed cassette 35 in which the recording media P are stacked and held, and a pickup roller 36 that feeds the recording media P from the paper feed cassette 35 one by one. It has.
[0030]
The paper transport unit 11 includes a registration roller pair 37 that defines the timing of feeding the recording medium P to the secondary transfer unit, and a secondary transfer roller as a secondary transfer unit that is pressed against the drive roller 12 and the intermediate transfer belt 14. 39, a recording paper conveyance path 38, a fixing unit 40, a discharge roller pair 41, and a duplex printing conveyance path 42.
[0031]
The fixing means 40 includes a heating member such as a halogen heater in at least one of the fixing roller pair 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 secondarily transferred to the recording medium P is pressed at a predetermined temperature at the nip formed by the fixing roller pair 40a. It is fixed on the medium. In the present embodiment, the fixing unit 40 is disposed in a space formed obliquely above the belt surface 14b facing upward in the transfer belt conveyance direction, in other words, in a space opposite to the image forming station with respect to the transfer belt. Therefore, heat transfer to the exposure unit 6, the intermediate transfer belt 14, and the image forming unit can be reduced, and the frequency of performing the color misregistration correction operation for each color can be reduced. In particular, the exposure unit 6 is located farthest from the fixing unit 40, can minimize the displacement of the scanning optical system component due to heat, and can prevent color misregistration.
[0032]
FIG. 3 shows a state in which the opening / closing member 3 is opened from the housing body 2.
The opening / closing member 3 is attached to the housing body 2 so as to be freely opened and closed. In the present embodiment, each unit can be attached and detached by accessing only from the front surface of the apparatus, and the apparatus can be installed in a compact room. Yes. A drive motor 61 is disposed in the opening / closing member 3, and a rotation lever 63 pivotally supported by the fixed shaft 62 is disposed. 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 shown by an arrow in FIG. The intermediate transfer belt 14 and the driving roller 12 can be pressed. An eccentric cam 65 is provided on the spring 64 side of the rotation lever 63. The rotating lever 63, the spring 64, and the eccentric cam 65 constitute a secondary transfer roller separating / contacting means.
[0033]
The rotation shaft of the drive motor 61 is connected to the shaft of the fixing roller 40a via a transmission device (not shown) consisting of a gear and a clutch, and via a transmission device (not shown) consisting of a gear and a clutch. The eccentric cam 65 is connected to the cam shaft. With this configuration, when the drive motor 61 rotates in the forward direction, the fixing roller 40a is driven, and when the drive motor 61 rotates in the reverse direction, the rotation of the eccentric cam 65 causes the rotation lever 63 to rotate against the spring 64 and the secondary transfer roller. 39 is moved away from the intermediate transfer belt 14 in the direction opposite to the arrow shown in the figure.
[0034]
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 driving engagement between the fixing means 40 and the drive motor 61 with heavy driving load is performed on the opening / closing member 3. It is possible to maintain the image quality by preventing the separation and engagement of the operation so as to prevent uneven recording paper conveyance and vibration of the entire apparatus due to poor engagement of the drive system. Further, when the recording motor is not conveyed, the drive motor 61 is rotated in the reverse direction so that 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 placed on the intermediate transfer belt 14. It is possible to perform a correction operation that is formed and read by a sensor, and a single drive source is not required for the contact and separation operation of the secondary transfer roller 39.
[0035]
FIG. 4 is a view for explaining attachment and replacement of consumables.
In the present embodiment, the housing main body 2 is provided with a shaft 66 that is a rotation fulcrum above the shaft 57 of the opening / closing member 3, and a rotating portion 50 formed of a frame is rotatably mounted on the shaft 66. The transfer belt unit 9 described with reference to FIG. The image forming unit and the transfer belt unit are exposed when the rotation unit 50 is rotated forward following the opening / closing member 3. In this state, the developing means 20, the image carrier unit (including the frame 67 a that supports the image carrier 17 and the charging means 19) 67, and the transfer belt unit 9 supported by the housing body 2 are removed for repair or replacement. It can be carried out. In this embodiment, after attaching the developing means 20 to the housing main body, the rotating portion 50 is rotated to position the image carrier 17 in contact with the developing roller, and the developing means is placed in the back of the main body. Since the image carrier 17 is brought into contact with the image carrier 17 after being disposed at a predetermined position, contamination due to toner leakage can be prevented. The image forming unit 7 may be supported by the rotating unit 50.
[0036]
FIG. 5 is a perspective view of the developing device of the present embodiment, FIG. 6 is a diagram for explaining the mounting of the developing device, FIG. 7 is a cross-sectional view of the developing device of the present embodiment when viewed from the non-driving side, and FIG. FIG. 9 is a cross-sectional view of the developing device of the embodiment as viewed from the drive side, and FIG. 9 is a diagram illustrating a state in which Y, M, C, and K developing devices are attached.
[0037]
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 and guide pins 74 and 75, which respectively form the rotation fulcrum of the developing device, are provided on the mounting plates. It is provided so as to protrude outward. Further, at both ends of the developing roller 33, contact rollers 77 that contact the end of the image carrier and rotate freely with the developing roller as a support shaft are provided to determine a relative position with respect to the image carrier. . The contact roller provides a gap between the developing roller and the image carrier in jumping development, but is also used for buffering between the development roller and the image carrier in pressure development, and a contact roller is provided. There are some types, and this embodiment can be applied to any type.
[0038]
On the other hand, as shown in FIG. 6, mounting grooves 2a and 2b for mounting the developing device are provided in the housing body 2 corresponding to both ends of the developing device, and rotating pins 72 and 73 and guides are provided in these grooves. The pins 74 and 75 are inserted in the direction indicated by the arrow (detachment direction), and the developing device is mounted. 6A is a mounting groove 2a as viewed from the side (drive side) where the developing device is driven by the drive gear supported by the main body, and FIG. 6B is as viewed from the opposite drive side that is opposite to the drive side. The mounting groove 2b is shown, and the rotation pin 72 is rotatably supported on the bottom of the mounting groove 2a on the driving side. On the other hand, the rotation pin 73 on the non-driving side is supported by being provided with a clearance in a direction orthogonal to the attaching / detaching direction of the groove so that it can move slightly. With this configuration, the developing device is supported at three points by the contact between the contact roller 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. Since it is movable within the range, the contact state between the developing device and the image carrier is stabilized.
[0039]
7 and 8 show a state in which a rotation pin and a guide pin are attached to the mounting grooves 2a and 2b of the housing body 2, and the developing device is rotated by an urging spring 2c having one end fixed to the housing body 2. The pins 72 and 73 are urged so as to rotate toward the image carrier 17 side. Therefore, when the image carrier 17 is not attached, the developing device is in a position where the urging spring 2c is extended, and the image carrier 17 is attached and pressed against the developing roller to lock the lever (not shown). ), The developing device is positioned while being pressed against the image carrier 17 by the biasing spring. With this configuration, there is no restriction on the positional relationship with the image carrier when the developing device is attached / detached, and the attaching / detaching operation becomes easy. In addition, since the attaching / detaching operation of the developing device and the function constituting the relative positional relationship between the developing device and the image carrier are divided into two, it is possible to construct a stable relative positional relationship without excessive operation. .
[0040]
In the developing device of this embodiment, the supply roller 31 and the development roller 33 are heavy, and the center of gravity is located near both rollers when viewed on the projection surface in the rotation axis direction of the roller. It arrange | positions so that the rotation pins 72 and 73 may be located in a perpendicular lower part. With such a configuration, it is possible to eliminate or suppress the rotational moment with respect to the rotation fulcrum (the rotation pins 72 and 73) due to the weight of the developing device. In this way, the rotational moment due to its own weight does not affect the contact roller between the developing roller and the image carrier, or the contact state between the developing roller itself and the image carrier, so the contact state between the developing device and the image carrier. Becomes stable and the image carrier can be driven to rotate with little rotational jitter, and the image is stabilized. Since the contact state between the developing device and the image carrier is thus stabilized, the degree of freedom in selecting the developing roller and the supply roller is widened, and an aluminum-based material having a relatively low specific gravity is selected as a base. Alternatively, even if the selection is made on the basis of an iron-based material having a relatively heavy specific gravity, the entire developing device is not affected, and the cost advantage can be selected while ignoring its own weight. Even when a rotational moment is generated with respect to the rotation fulcrum due to the weight of the developing device, it is preferable that the rotational moment acts in a direction in which the developing roller 33 is separated from the image carrier 17.
[0041]
The developing device is driven by meshing between a driving gear 80 attached to the housing main body 2 and a driven gear 81 on the developing device side, and the rotation of the driven gear 81 is supplied through the gear train meshing with the supply roller 31, This is transmitted to the developing roller 33 and the toner stirring member 29. When viewed from the projection surface in the roller rotation axis direction of the developing device, the position of the meshing portion of the drive gear 80 and the driven gear 81 overlaps or is at least in the vicinity of the rotation fulcrum (rotation pins 72 and 73). To do. As a result, the reaction force generated by the driving does not act on the developing device as a rotational moment with respect to the rotation fulcrum, or is suppressed to be small. With such a 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 be configured to act in a direction away from the image carrier 17 even when a rotational moment is generated.
[0042]
Similarly, when viewed from the rotation axis direction projection surface of the developing device, the contact roller 77 is driven by the image carrier by the contact between the contact roller 77 and the image carrier 17 or driven by the developing roller. When the developing roller 33 and the image carrier 17 are rotated in contact with each other without the contact roller, the image carrier and the contact roller or the image carrier are rotated. A driving reaction force is generated in the direction of the solid arrow A in the figure in the tangential direction of the contact portion between the body and the developing roller. If there is a difference in the rotational peripheral speed between the developing roller and the image carrier, the reaction force is generated according to the peripheral speed difference. That is, when the rotation speed of the developing roller or the contact roller is higher than the rotation speed of the image carrier, the developing roller generates in the direction of the solid arrow in the figure, and conversely the development roller with respect to the rotation speed of the image carrier. Or, when the rotational peripheral speed of the contact roller is slow, it occurs in the direction opposite to the solid arrow. Therefore, the direction of the driving reaction force is the rotation fulcrum or rotation as shown by the solid line arrow A in the figure so that no rotational moment is generated with respect to the rotation fulcrum (rotation pins 72 and 73) by the drive reaction force. Try to be near the fulcrum. With such an arrangement, the reaction force generated by the contact with the image carrier does not give the developing device a moment about the rotation fulcrum, and the rotation of the image carrier becomes unstable due to the drive reaction force. Can be prevented.
[0043]
Further, the drive-side rotation pin 72 is supported at the bottom of the mounting groove 2a in the mounting direction and in the direction orthogonal to the mounting direction. On the other hand, the rotation pin 73 on the counter driving side is supported in the mounting direction in the mounting groove 2b, and in the direction orthogonal to the mounting direction, a driving reaction force generated between the contact roller of the developing roller and the image carrier. Is provided with a movable clearance. For this reason, the developing roller 33 and the image carrier 17 have a so-called three-point contact structure of the drive-side rotation pin 72 and the two contact rollers 77, so that the contact state can be stabilized.
[0044]
Further, the rotation fulcrum (the rotation pins 72 and 73) is supported in the mounting groove bottom portion so as to be opposed to the mounting direction, and the force acting when the driven gear 81 is driven from the drive gear 80 is reduced by the mounting groove bottom portion. Therefore, the developing device is supported in a stable state and the relative positional relationship with the image carrier is maintained in a preferable relationship.
[0045]
Further, the driven gear 81 is disposed at a position orthogonal to or in the vicinity of the driving gear 80 with respect to the mounting / demounting direction of the developing device (the arrow direction parallel to the mounting groove in FIGS. 7 and 8). At this time, the direction in which the driven gear 81 is engaged with the driving gear 80 is the direction of the mounting groove, so that the driven gear 81 can be easily engaged with or detached from the driving gear 80 when the developing device is attached or detached. As a result, there is no need to separately provide an auxiliary mechanism for the purpose of stabilizing engagement and separation.
[0046]
In the present embodiment, as shown in FIG. 4, the rotation unit 50 can be rotated to remove the image carrier, and the developing device can be attached and detached in that state. Is mounted on the apparatus main body, and then the rotating portion 50 is rotated to press and press the image carrier 17 against the developing device, and the position of the image carrier is determined by the lock lever. . In this way, the developing device is first set in a place where the apparatus main body is difficult to move, the image carrier is pressed and positioned from above, and the intermediate transfer belt is further provided on the developing device. It is possible to prevent toner contamination on other parts.
[0047]
In addition, the direction in which the developing device is inserted (the direction of the mounting groove) is the gravitational direction, and the developing device is inserted in a direction opposite to the contact direction with the image carrier, and the gravitational direction causes the developing device to In the direction of separation, the contact pressure with the image carrier is reduced, and the contact between the developing device and the image carrier is favorably affected.
[0048]
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 heads of the adjacent developing devices enter. This position overlaps with the adjacent developing device. As described above, since the rotation fulcrum can be disposed so as to overlap with the adjacent developing device, space saving can be achieved.
[0049]
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 rotational moment is generated with respect to the rotation fulcrum. Also good.
[0050]
【The invention's effect】
As described above, according to the present invention, the developing device can be detached by displacing the image carrier, and the developing device is positioned by the image carrier when the image carrier is displaced to the operating position. Therefore, replacement and positioning of the developing device and the image carrier are facilitated.
In addition, after the developing device is installed, the image carrier is placed in contact with the developing device and positioned, so that the developing device is placed in the back of the main body, thus preventing contamination due to toner leakage. be able to.
Further, since the developing device is rotated at the rotation fulcrums at both ends and is brought close to and separated from the image carrier, the contact between the developing device and the image carrier is stabilized.
Further, since the rotation fulcrum member is detachably mounted and supported in the mounting groove formed in the apparatus main body, the developing device can be easily mounted and stably supported.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an entire 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 for explaining 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 the developing device.
FIG. 7 is a cross-sectional view of the developing device as viewed from the non-driving side.
FIG. 8 is a cross-sectional view of the developing device as viewed from the driving side.
FIG. 9 is a diagram showing an attached state of Y, M, C, and K developing devices.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Housing main body, 2a, 2b ... Mounting groove, 2c ... Energizing spring, 17 ... Image carrier, 20 ... Developing means, 31 ... Supply roller, 33 ... Developing roller, 70, 71 ... Mounting plate, 72, 73 ... Rotating pin (rotating fulcrum), 74, 75 ... guide pin, 77 ... contact roller, 80 ... driving gear, 81 ... driven gear

Claims (1)

An image having a detachable developing device, wherein the developing device is positioned by the image carrier when the image carrier is displaced to the operating position, and the image carrier is rotationally displaceable with respect to the apparatus main body. In the forming device,
In the developing device, a rotation pin and a guide pin that form a rotation fulcrum provided at both ends of a lower portion in the vertical direction are detachably mounted in a mounting groove formed in the apparatus main body, and developed by a driving device. The rotation pin on the drive side where the device is driven is supported in the mounting groove bottom in the mounting direction and the direction orthogonal to the mounting direction, and the rotation pin on the side opposite to the drive side is supported in the mounting direction on the mounting groove bottom. An image forming apparatus, wherein a clearance is provided and supported in a direction orthogonal to the mounting direction.

Images