JPH04368963A - Image forming device - Google Patents

Abstract

PURPOSE:To improve image quality by providing an abutting part for a processing cartridge other than a center positioning part of a photosensitive drum on main body frame side. CONSTITUTION:An opening/closing cover 5 is closed until a lock hole part 5c is engaged with a lock. Then, the processing cartridge abutting part 5b of the opening cover 5 is abutted to an abutting part 4a of the processing cartridge frame body and a back part of the processing cartridge 2 is pressed down. The positioning pin outside flange 3a of the photosensitive drum is abutted to a positioning part 1a of the main frame 1 and positioning of the photosensitive drum 10 is carried out. Furthermore, since a front part of the processing cartridge 2 is pushed down by a processing cartridge pressing spring 6, the center of the photosensitive drum 10 is always pressed to the positioning part 1a of the main frame 1 with the abutting part 5b as a supporting point. In this case, a large amount of the force floating up the processing cartridge 2 is imparted to the abutting part 5b of the main body, and a small amount is imparted to a pressing spring 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge holding device for an image forming apparatus equipped with a process cartridge, such as an electrophotographic apparatus such as a laser beam printer (hereinafter abbreviated as LBP) or a copying machine.

0002

[Prior Art] Electrophotographic devices such as small LBPs and copying machines are required to be easy to maintain by users, prevent toner stains, and reduce costs. A so-called process cartridge is used as the core of the process. The process cartridge can be easily taken in and out of the electrophotographic apparatus, and is generally positioned only after it is inserted into the main body and the opening/closing cover of the main body is closed.

FIG. 11 shows a conventional LBP. Image information sent from the laser scanner 107 is sent to the reflection mirror 1
06 and sent to the process cartridge 120, the toner image is scanned in the longitudinal direction of the rotating photosensitive drum 10 inside, and after the well-known image formation, the toner image moves to the part facing the transfer roller 11. At the same time, the transfer material 112 is fed out one sheet by the paper feed roller 111, and the transfer material 112 is fed out one sheet by the paper feed roller 111,
The transfer material synchronized in step 5 passes between the transfer roller 11 and the photosensitive drum 10, transfers the toner image thereon, is sent to the fixing device 103, and is discharged outside the machine through a pair of paper discharge rollers 102 and a paper discharge path 104. be done.

As shown in FIGS. 10 and 11, the drum positioning pin 122 provided on the process cartridge 120 and the axis of the photosensitive drum 10 inside the process cartridge 120 are aligned, and as shown in FIG. A drum gear 110 extends outside the process cartridge 120 together with the photosensitive drum 10, and meshes with a drive gear 121 on the main body side. The process cartridge 120 is shown in FIG.
0, the main body opening/closing door 100, which is pivotally connected to the main body frame 113 with a hinge 105, is opened and placed in a guide member 114 provided on the door 100. At this time, the process cartridge 120 is only floatingly supported by the opening/closing door 100 and is not positioned, and the pressure springs 101a and 101b provided on the door 100 do not act. There, 100 opening/closing doors
When the door 100 is closed until the pin 108 of the main body frame 113 engages with the lock member 109 provided on the main body frame 113, the outer flange 122a of the drum positioning pin 122 of the process cartridge 120 fits into the U groove 113a of the main body frame 113, and the process cartridge 120 is main body frame 1
13 with the center of the photosensitive drum 10 as a reference.

Further, since the process cartridge 120 is subjected to downward force by the pressing springs 101a and 101b, it maintains its position even after being driven, and at the same time, it is able to maintain its position even after being driven.
Changes in moment applied to the process cartridge 120 due to load fluctuations and the like are also absorbed by the deflection of the pressing springs 101a and 101b.

[0006]

However, in the above conventional example, the process cartridge 120 is attached to the main body frame 11.
The process cartridge 1 is supported only by the U/groove 113a of 3 and the positioning pin 122 at the center of the photosensitive drum 10.
Pressure springs 101a and 101b provided on all sides prevent rotation of the process cartridge 20 itself and maintain the posture of the process cartridge 120.
Because this was done by

As shown in FIG. 4, a process cartridge 120
A moment M is applied to the entire structure around the center of the photosensitive drum 10. At this time, if the moment M changes due to load fluctuations, torque fluctuations, etc., the pressure springs 101a and 101b absorb the change while being deflected, making the posture of the process cartridge 120 unstable. Also, the pressure spring 101a, 1
01b (particularly in the case of a leaf spring), the posture holding ability differs depending on the machine, and if mass production is performed, stable images cannot be obtained. Further, since the drum gear 110 receives a tooth load in the direction of the pressure angle of the gear, a force F that lifts the photosensitive drum 10 acts only on the side where the drum gear 110 is located (FIG. 5). In this case as well, the force for lifting the photosensitive drum 10 changes due to torque fluctuations, so as described above, the pressure springs 101a and 101b alone may not be able to absorb the force and the position of the photosensitive drum 10 relative to the main body frame 113 may not be stable.

As a result, as shown in FIG.
The imaging position of the image information reflected at 06 on the photosensitive drum 10 is distorted, which affects the image. In particular, when an imaging lens with a shallow depth of focus is used, the image is adversely affected. Furthermore, not only the image but also the transfer roller pressure becomes unstable when the transfer roller 11 is used, which adversely affects the printing accuracy on the transfer material. Also, the process cartridge 120, the pressure springs 101a, 1
Since 01b is required at four locations, it is disadvantageous in terms of cost.

[0009]

[Means for Solving the Problems] According to the present invention, in addition to the photosensitive drum center positioning part, a process cartridge abutting part is provided on the main body frame side, and the moment and lifting force applied to the entire process cartridge when the main body is operated is reduced. The above-mentioned problems are solved by directly receiving it on the main body side without using an elastic member. Furthermore, since the number of pressure springs can be reduced, there is also an effect of cost reduction.

The first aspect of the present invention is a unitized process in which a cylindrical image bearing member is driven from the apparatus main body side and members for performing at least one image forming step are arranged around the image bearing member. The image carrier has a cartridge, and the position of the image carrier with respect to the main body is determined by fitting the center positioning part of the image carrier of the process cartridge with the cartridge positioning part of the main body, and the process cartridge is removably supported with respect to the main body. The image forming apparatus is characterized in that the process cartridge is provided with an abutment portion against which the process cartridge abuts against the main body in the direction of a moment centered on the image carrier that is applied to the process cartridge.

The second aspect of the present invention is the first aspect characterized in that a pressing member for pressing the process cartridge is provided on the side opposite to the abutting portion on the main body side with the positioning portion of the image carrier in between. This is an image forming apparatus according to the invention.

A third aspect of the present invention is characterized in that a second process cartridge abutting portion is provided on the main body side on the opposite side to the abutting portion on the main body side with the positioning portion of the image carrier in between. An image forming apparatus according to a first aspect of the present invention.

[0013]

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a drawing that best represents the features of the present invention, and is a perspective view of a state in which a process cartridge is installed and an opening/closing cover is closed. In the figure, a main frame 1 constituting the main body has a positioning portion 1 for a process cartridge 2.
It has a. A process cartridge 2 including a photosensitive drum, a developing device, a cleaning device, etc. has a drum positioning pin 3 that pivotally supports the photosensitive drum on a process cartridge frame 4, and the drum positioning pin 3 has an external flange 3a serving as a bearing and an external flange. Drum shaft 3 supported by 3a
b, and is configured such that a photosensitive drum fixed to a drum shaft 3b rotates coaxially with the external flange 3a. The positioning part 1a is located on the back side of the guide track 1d of the main frame 1 of the main body, where the external flange 3a of the drum positioning pin is guided when the opening/closing cover 5 of the main body is opened and the process cartridge 2 is inserted into the main body. It is positioned by the rear part 1c and the lower four-part circular part 1e facing the rear part 1c. That is, the rear portion 1c is located at a position opposing the tooth load applied to the drum gear 110 shown in FIG. 5, and the four-part circular portion 1e is in contact with the outer periphery of the external flange 3a. The opening/closing cover 5, which is opened and closed when replacing the process cartridge 2 or clearing a jam, is attached to the hinge 5a of the opening/closing cover 5 on the shaft support 1b of the main frame 1.
are engaged and can be opened and closed. Further, the lock hole 5c provided at the open end of the cover 5 engages with a lock 7 provided on the main frame 1, so that the cover is closed. In the lock 7, a detent pawl 1g pivotally supported on the main frame 1 by a shaft 1f is biased outward in a limited manner by a torsion coil spring 1h. On the back side of the opening/closing cover 5, there is an abutment part 5 that abuts against the abutment part 4a of the process cartridge frame 4.
A pressing spring 6 that presses the front portion of the process cartridge 2 and the process cartridge 2 is provided.

FIGS. 2 and 3 are side views of FIG. 1. FIG. 2 shows the process cartridge in a used state with the process cartridge positioned, and FIG. 3 shows the process cartridge in an unpositioned state with the opening/closing cover open.

As shown in FIG. 3, the process cartridge 2 is inserted from the direction of arrow A with the opening/closing cover 5 opened until it reaches a position where the drum positioning pin external flange 3a abuts the rear part 1c of the positioning portion 1a of the main frame 1. At this time, the photosensitive drum 10 is pushed up by the pressing force of the transfer roller 11 and is not regulated by the process cartridge abutting portion 5b of the open/close cover 5 and the process cartridge pressing spring 6, so the process cartridge 2 is not positioned. Therefore, the lock hole 5c of the opening/closing cover 5 is locked with the lock 7.
When the process cartridge abutting portion 5b of the open/close cover 5 is closed until it engages with the process cartridge frame 4,
The photosensitive drum positioning pin external flange 3a contacts the positioning portion 1a of the main frame 1, and the photosensitive drum 10 is positioned. Further, since the process cartridge pressing spring 6 presses down the front part of the process cartridge 2, the photosensitive drum 10 is pushed down using the abutment part 5b as a fulcrum.
The structure is such that the center of the main frame 1 is always held against the positioning portion 1a of the main frame 1. When the main body is operated in this state, the drum gear 110 receives a rotational force from the drive gear 121 (see FIG. 5) of the main body, and a moment M about the photosensitive drum 10 is applied to the process cartridge 2 as a whole. We try to rotate it clockwise in Figure 2. Therefore, the process cartridge abutting portion 5b of the opening/closing cover 5 receives this force, so that the posture of the process cartridge 2 is more stable than when an elastic body is used. Also, due to torque fluctuation, the moment M suddenly disappears,
In the unlikely event that the process cartridge attempts to return counterclockwise, the process cartridge pressing spring 6 can absorb this movement. The force for lifting the process cartridge 2 based on the tooth load of the drum gear 110 is largely applied to the abutting portion 5b of the main body, and less is applied to the pressing spring 6, so that the process cartridge does not float. As described above, the present invention stabilizes the posture of the process cartridge when the main body is in operation.

"Other Embodiments" FIG. 6 shows a second embodiment of the present invention. In this example, the member against which the rear part of the process cartridge 2 abuts is not the opening/closing cover 22 but the abutting plate 21d of the main frame 21. The effect is similar to that of the first embodiment, and the fixing member receives the moment M applied to the process cartridge 2 during operation of the main body and the lifting force due to the drum gear tooth load.

FIG. 7 shows a third embodiment of the present invention. Here, the process cartridge 2 is pressed against the abutment plate 31d of the main frame 31 at the front lower part thereof, and the pressing spring 33 provided on the opening/closing cover 32 prevents the rear part from rising.

FIG. 8 shows a fourth embodiment of the present invention. Here, the main frame 41 is provided with a rear portion 1c into which the drum positioning pin external flange 3a is fitted, and an enclosure 41a consisting of upper and lower sides following the rear portion 1c, thereby achieving positional accuracy of the photosensitive drum 10 relative to the main body. The moment M applied to the process cartridge 2 is received by the abutting plate 41d provided on the main frame 41, and the lifting force due to the drum gear tooth load is received by the abutting plate 41d and the enclosure 41a, thereby obtaining the same effect as described above.

FIG. 9 shows a fifth embodiment of the present invention. Here, the main frame 51 is provided with abutting plates 51d and 51e at the rear upper part and the front lower part of the process cartridge 2, so that the moment M is received as a couple. In this case, depending on the dimensional accuracy of the main frame 51, the misalignment can be absorbed by slightly reducing the rigidity of the process cartridge frame 4.

[0020]

[Effects of the Invention] As explained above, in addition to the drum positioning section, a process cartridge abutting section is provided on the main body side.
By using a rigid body to absorb the moment acting on the process cartridge, the tooth load that lifts the photosensitive drum, and torque fluctuations, the posture of the process cartridge and even the photosensitive drum can be prevented from becoming unstable, thereby preventing negative effects on images or printing accuracy. It becomes possible to prevent this. Furthermore, the number of pressure springs that were conventionally provided at four locations in a process cartridge can be reduced to two or less, resulting in a cost reduction effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an LBP implementing the present invention.

FIG. 2 is a side view showing the state of use of FIG. 1;

FIG. 3 is a side view showing the opening/closing cover of FIG. 1 in an open state.

FIG. 4 is a side view showing the moment acting on the process cartridge during operation.

FIG. 5 is a front view showing how the photosensitive drum is pushed up by the drum gear.

FIG. 6 is a side view showing another embodiment.

FIG. 7 is a side view showing another embodiment.

FIG. 8 is a side view showing another embodiment.

FIG. 9 is a side view showing another embodiment.

FIG. 10 is a side view of a conventional example.

FIG. 11 is a side view of a conventional example.

[Explanation of symbols]

1 Mainframe 1a Positioning part 1b Axial branch 2 Process cartridge 3 Drum positioning pin 3a External flange 3b Drum shaft 4 Process cartridge frame 5 Opening/closing cover 5a Hinge 5b Abutment part 5c Lock hole part 6 Pressure spring 7 Lock 10 Photosensitive drum 11 Transfer roller

Claims (3)

[Claims] 1. A process cartridge comprising a cylindrical image bearing member driven from the apparatus main body side and a unitized process cartridge in which members for performing at least one image forming process are arranged around the image bearing member. In an image forming apparatus in which the position of the image carrier with respect to the main body is determined by fitting the center positioning part of the image carrier with the cartridge positioning part of the main body, and the process cartridge is removably supported with respect to the main body, An image forming apparatus characterized in that the process cartridge is provided with an abutting portion where the process cartridge abuts against the main body side in the direction of a moment centered on the image carrier that is applied to the cartridge. 2. The image forming apparatus according to claim 1, further comprising a pressing member for pressing the process cartridge on the side opposite to the abutting portion on the main body side with the positioning portion of the image carrier in between. . 3. A second process cartridge abutment portion is provided on the main body side on the opposite side to the abutment portion on the main body side with the positioning portion of the image carrier in between. image forming device.