JP7483540B2 - Cartridge and image forming apparatus - Google Patents

Description

The present invention relates to an electrophotographic image forming apparatus (image forming apparatus) and a cartridge used therein.

An electrophotographic image forming apparatus (image forming apparatus) is an apparatus that forms an image on a recording medium using an electrophotographic image forming method. Examples of image forming apparatuses include electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers, etc.), facsimile machines, and word processors.

The cartridge is configured to be detachable from the main body of the image forming device. An example of a cartridge is a process cartridge. A process cartridge is a cartridge that has an electrophotographic photosensitive member (photosensitive member) and a process means that acts on the photosensitive member. Examples of the process means include a developing means, a charging means, and a cleaning means. By using a cartridge, maintenance of the image forming device can be performed by replacing the cartridge.

In Patent Document 1, the process cartridge has a configuration in which a developing unit having a developing roller is movably coupled to a drum unit having a photosensitive drum. The process cartridge has a spring that urges the developing unit toward the drum unit, and the developing roller is in contact with the photosensitive drum. When an image forming operation is not being performed, the developing unit is urged by a spacing member provided in the main body of the image forming device, and the developing roller is spaced from the photosensitive drum. (Patent Document 1)
In some image forming apparatuses, the weight of the developing device is used to separate the developing roller from the photosensitive drum, and a pressing member provided in the main body of the image forming apparatus is used to press the developing device, so that the developing roller comes into contact with or is close to the photosensitive drum (see Patent Documents 2 and 3).

JP 2009-288302 A JP 2002-174938 A JP 2012-58627 A

The present invention is a further development of conventional technology. The present invention relates to a cartridge having a first unit with a photosensitive member and a second unit with a developer carrier, in which the developer carrier is separated from the photosensitive member by the weight of the second unit, and to an image forming apparatus equipped with the above-mentioned cartridge. The object of the present invention is to suitably arrange a force receiving portion that receives a force for bringing the developer carrier into contact with the photosensitive member, the rotation axis of the second unit, and the developer carrier.

One of the inventions related to this application is as follows:

A cartridge to be mounted in a main body of an image forming apparatus for performing an image forming operation,
a first unit including a photoconductor;
a second unit coupled to the first unit and including a developer carrier and a force receiving portion, the second unit being rotatable about a first axis so as to move relative to the first unit between a first position where the developer carrier contacts the photoconductor and a second position where the developer carrier is separated from the photoconductor, and being configured to be located at the first position when the force receiving portion receives a force from the device main body;
having
the second unit is configured to be located at the second position by its own weight when the first unit is in the same position as when the image forming operation is performed, and the developer carrier and the force receiving portion are located above a horizontal line passing through the first axis;
the developer carrier is configured to be rotatable about a second axis;
When viewed in the direction of the first axis, a first distance between the force receiving portion and the second axis is shorter than a second distance between the first axis and the second axis and a third distance between the first axis and the force receiving portion.

One of the inventions related to this application is as follows:

A cartridge to be mounted in a main body of an image forming apparatus,
a first unit including a photoconductor and configured to be supported by the main body of the apparatus;
a second unit coupled to the first unit and including a developer carrier and a force receiving portion, the second unit being rotatable about a first axis so as to move relative to the first unit between a first position where the developer carrier contacts the photoconductor and a second position where the developer carrier is separated from the photoconductor, and being configured to be located at the first position when the force receiving portion receives a force from the device main body;
having
the second unit is configured to be located at the second position by its own weight in a state in which the first unit is supported by the apparatus main body, and the developer carrier and the force receiving portion are located above a horizontal line passing through the first axis;
The cartridge is characterized in that the developer carrier is configured to be rotatable around a second axis, and in a direction perpendicular to the first axis, a first distance between the force receiving portion and the second axis is shorter than a second distance between the first axis and the second axis and a third distance between the first axis and the force receiving portion.

The present invention can also be applied to image forming devices that have the above cartridges.

As described above, according to the present invention, the force receiving portion that receives the force for bringing the developer carrier into contact with the photosensitive member, the rotation axis of the second unit, and the developer carrier can be suitably positioned.

Cross-sectional view of a process cartridge Schematic diagram of an image forming apparatus Cross-sectional view of a process cartridge FIG. 2A is a perspective view of the process cartridge as viewed from the bottom side; FIG. 2B is a perspective view of the process cartridge as viewed from the top side; FIG. 3 is an exploded perspective view showing the connection between the photoconductor unit and the developing unit. FIG. 2A is a cross-sectional view of the process cartridge when the developing unit is in the separated position, and FIG. 2B is a cross-sectional view of the process cartridge when the developing unit is in the image forming position. (a) is a schematic diagram when the center of gravity is located below a horizontal line passing through the rotation axis of the developing unit, and (b) is a schematic diagram when the center of gravity is located above a horizontal line passing through the rotation axis of the developing unit. Side view of the process cartridge

[Example 1]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiment may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions, and the scope of the present invention is not limited to the following embodiment.

<Overall Configuration of Image Forming Apparatus 100>
The overall configuration of an electrophotographic image forming apparatus 100 (hereinafter, image forming apparatus 100) according to this embodiment will be described with reference to FIG.

Figure 2 is a schematic diagram of the image forming apparatus 100 according to this embodiment. The up-down direction in Figure 2 indicates the vertical direction when the image forming apparatus 100 is used (when an image forming operation is performed). The left-right direction in Figure 2 indicates the horizontal direction when an image forming operation is performed.

The image forming apparatus 100 has an apparatus main body 100a. In this embodiment, the image forming apparatus 100 has process cartridges 1 (1Y, 1M, 1C, 1K) and toner cartridges 13 (13Y, 13M, 13C, 13K). The process cartridges 1 (1Y, 1M, 1C, 1K) and toner cartridges 13 (13Y, 13M, 13C, 13K) are detachable from the apparatus main body 100a. In other words, the process cartridges 1 (1Y, 1M, 1C, 1K) and toner cartridges 13 (13Y, 13M, 13C, 13K) are detachably attached to the apparatus main body 100a.

The first process cartridge 1Y contains yellow (Y) developer (hereafter referred to as toner) TY in the development unit 6. The second process cartridge 1M contains magenta (M) toner TM. The third process cartridge 1C contains cyan (C) toner TC. The fourth process cartridge 1K contains black (K) toner TK.

Each process cartridge 1 (1Y, 1M, 1C, 1K) has a photoconductor unit 4 (4Y, 4M, 4C, 4K) and a developing unit 6 (6Y, 6M, 6C, 6K) described below. Each process cartridge 1 (1Y, 1M, 1C, 1K) transfers toner to an intermediate transfer belt 18 (described below) at a primary transfer section S1 (S1Y, S1M, S1C, S1K).

The first toner cartridge 13Y contains yellow (Y) toner. The second toner cartridge 13M contains magenta (M) toner. The third toner cartridge 13C contains cyan (C) toner. The fourth toner cartridge 13K contains black (K) toner.

Each toner cartridge 13 (13Y, 13M, 13C, 13K) is disposed below the process cartridge 1 (1Y, 1M, 1C, 1K) that contains toner of the same color. Each toner cartridge 13 (13Y, 13M, 13C, 13K) supplies toner to the process cartridge 1 (1Y, 1M, 1C, 1K) that contains toner of the same color.

Each process cartridge 1 (1Y, 1M, 1C, 1K) and each toner cartridge 13 (13Y, 13M, 13C, 13K) are arranged side by side in the horizontal direction.

The first to fourth toner transport devices 14 (14Y, 14M, 14C, 14K) are disposed below each toner cartridge 13 (13Y, 13M, 13C, 13K). Each toner transport device 14 (14Y, 14M, 14C, 14K) transports the toner received from each toner cartridge 13 (13Y, 13M, 13C, 13K) upward and supplies the toner to each development unit 6 (6Y, 6M, 6C, 6K).

The refill operation for each toner cartridge 13 (13Y, 13M, 13C, 13K) is performed when a toner remaining amount detection unit (not shown) provided in the device main body 100a detects that the toner in each process cartridge 1 (1Y, 1M, 1C, 1K) is low.

In this embodiment, the first to fourth process cartridges (1Y, 1M, 1C, 1K) have substantially the same configuration and perform the same operation, except that the toner colors they contain (the colors of the images they form) are different. Similarly, the first to fourth toner cartridges (13Y, 13M, 13C, 13K) have substantially the same configuration and perform the same operation, except that the toner colors they contain are different. Similarly, the first to fourth toner transport devices (14Y, 14M, 14C, 14K) have substantially the same configuration and perform the same operation, except that the toner colors they transport are different. Therefore, in the following description, unless a distinction is particularly necessary, the suffixes Y to K will be omitted.

The process cartridge 1 has a photosensitive unit (first unit, image carrier unit, photosensitive unit) 4 with a photosensitive drum 7, and a developing unit (second unit) 6 with a developing roller 11. The process cartridge 1 has one photosensitive unit 4 and one developing unit 6. That is, the process cartridge 1 has one photosensitive drum 7 and one developing roller 11.

The photosensitive unit 4 has a photosensitive drum 7 as an image carrier (photosensitive member) that carries an electrostatic latent image, and a charging roller 8 as a charging member that charges the surface of the photosensitive drum 7. The photosensitive unit 4 has a cleaning blade 10 as a cleaning member that cleans the photosensitive drum 7. The photosensitive drum 7 rotates by receiving a driving force from the device main body 100a.

The developing unit 6 contains toner T. The developing unit 6 has a developing roller 11 as a developing means for developing the electrostatic latent image formed on the photosensitive drum 7. The developing roller 11 is a developer carrier that carries the toner T and develops the electrostatic latent image formed on the photosensitive drum 7 with the toner T. The developing roller 11 rotates by receiving a driving force from the device main body 100a. As described below, the photosensitive unit 4 and the developing unit 6 are connected so as to be able to swing.

The process cartridge 1 is configured to be detachable from the device main body 100a via mounting means such as a mounting guide and a positioning member provided on the device main body 100a. In this embodiment, the process cartridge 1 is mounted along the direction of the rotation axis of the photosensitive drum 7. Note that in this embodiment, the direction of the rotation axis of the photosensitive drum 7 is parallel to the direction of the rotation axis of the developing roller 11. Therefore, it can also be said that the process cartridge 1 is mounted along the direction of the rotation axis of the developing roller 11.

When the process cartridge 1 is attached to the device main body 100a, the photosensitive unit 4 is supported by a positioning member of the device main body 100a, and the photosensitive unit 4 is positioned relative to the device main body 100a. As a result, the process cartridge 1 is positioned relative to the device main body 100a with the development unit 6 movable relative to the device main body 100a and the photosensitive unit 4.

The toner cartridge 13 is detachably attached to the device main body 100a via attachment means such as a toner cartridge attachment guide and a toner cartridge positioning member provided on the device main body 100a.

A scanner (exposure device) 12 is disposed below the process cartridge 1 for exposing the photosensitive drum 7 to light and forming an electrostatic latent image on the photosensitive drum 7. The device main body 100a also has a removed toner transport unit 23. The removed toner transport unit 23 transports the removed toner removed from the photosensitive drum 7 by the cleaning blade 10 to a removed toner collection container 24. The removed toner transport unit 23 is disposed downstream of the process cartridge 1 in the mounting direction of the process cartridge 1.

An intermediate transfer unit 19 is provided above the process cartridge 1 as an intermediate transfer body. The intermediate transfer unit 19 is arranged so that the primary transfer section S1 (S1Y, S1M, S1C, S1K) is located below.

The intermediate transfer unit 19 has an intermediate transfer belt 18, a primary transfer roller 20 as a primary transfer member, a secondary transfer roller 21 as a secondary transfer member, and a belt cleaning unit 4. The intermediate transfer belt 18 facing the photosensitive drum 7 is an endless (closed loop) belt that can rotate in the direction of arrow B, and is stretched around multiple tension rollers. The primary transfer roller 20 is disposed inside the intermediate transfer belt 18. The primary transfer roller 20 faces the photosensitive drum 7 through the intermediate transfer belt 18, forming a primary transfer section S1. The secondary transfer roller 21 contacts the intermediate transfer belt 18, faces the opposing roller through the intermediate transfer belt 18, and forms a secondary transfer section S2. Furthermore, the belt cleaning unit 4 is disposed on the opposite side of the secondary transfer section S2 in the left-right direction. More specifically, with respect to the rotation direction of the intermediate transfer belt 18, the belt cleaning unit 4 is disposed downstream of the secondary transfer section S2 and upstream of the primary transfer section S1.

A fixing unit 25 is disposed above the intermediate transfer unit 19. The fixing unit has a heating unit 26 and a pressure roller 27 that is pressed against the heating unit. Furthermore, an output tray 32 is disposed above the device main body 100a, and a removed toner recovery container 24 is disposed between the output tray 32 and the intermediate transfer unit. Furthermore, a paper feed tray 2 for storing recording material (medium, recording medium) 3 such as paper is disposed at the bottom of the device main body 100a.

In other words, in the image forming device 100, the process cartridge 1 and the scanner 12 are disposed below the intermediate transfer unit 19. Therefore, the photosensitive drum 7, the developing unit 6, and the scanner 12 are disposed on the opposite side of the intermediate transfer unit 19 from the fixing unit 25. This allows the photosensitive drum 7, the developing unit 6, and the scanner 12 to be disposed at a position away from the fixing unit 25. This makes it possible to prevent the photosensitive drum 7, the developing unit 6, and the scanner 12 from being affected by heat from the fixing unit 25.

<Image Forming Operation>
Next, the image forming operation in the image forming apparatus 100 will be described with reference to FIGS.

Figure 3 is a cross-sectional view of the process cartridge according to this embodiment. The up-down direction in Figure 3 indicates the vertical direction when the image forming operation is performed. The left-right direction in Figure 3 indicates the horizontal direction when the image forming operation is performed. In other words, Figure 3 shows the process cartridge 1 when it is attached to the device main body 100a and when the image forming operation is performed.

The device main body 100a is provided with a control unit 100C including a CPU, a memory, etc., and a driving source 100M including a motor. The control unit 100C controls the driving source 100M and the scanner 12, etc., to perform an image forming operation. In this embodiment, the driving source 100M includes a motor that drives a force applying unit 101 described later. The driving source 100M drives components other than the force applying unit 101, such as the photosensitive drum 7, the developing roller 11, the intermediate transfer belt 18, and a conveying member for conveying the recording material 3. The driving source 100M may drive these components with one motor or multiple motors. When an image forming operation is performed, the photosensitive drum 7 is rotated in the direction of arrow A in FIG. 3. The intermediate transfer belt 18 is rotated in the direction of arrow B in FIG. 2.

First, the surface of the photosensitive drum 7 is uniformly charged by the charging roller 8. Next, the surface of the photosensitive drum 7 is scanned and exposed by laser light emitted from the scanner 12. Then, an electrostatic latent image based on the image information is formed on the surface of the photosensitive drum 7.

The electrostatic latent image formed on the photosensitive drum 7 is developed into a toner image by the developing unit 6. More specifically, the electrostatic latent image is visualized by the toner T when the developing roller 11 comes into contact with the photosensitive drum 7. As described below, when an image forming operation is performed, the developing unit 6 is pressed by a force applying portion 101 provided in the device main body 100a, so that the developing unit 6 is positioned at the image forming position.

The toner image formed on the photosensitive drum 7 is transferred to the intermediate transfer belt 18 by the primary transfer roller 20 (primary transfer process). When a color image is formed, the above-mentioned image forming operation is performed sequentially at the first to fourth primary transfer units S1Y to S1K. As a result, a toner image of each color is formed on the intermediate transfer belt 18. The image forming device 100 can form a single-color image using one of the first to fourth process cartridges (1Y, 1M, 1C, 1K). The image forming device 100 can also perform image forming operations using two or three of the first to fourth process cartridges (1Y, 1M, 1C, 1K).

Meanwhile, the recording material 3 stored in the paper feed tray 2 is transported to the secondary transfer section S2. Then, the toner images carried on the intermediate transfer belt 18 are transferred all at once to the recording material 3 by the secondary transfer roller 21 (secondary transfer process).

The recording material 3 onto which the toner image has been transferred is transported to the fixing unit 25. In the fixing unit 25, the recording material 3 is heated and pressurized, so that the toner image is fixed onto the recording material 3. The recording material 3 onto which the toner image has been fixed is discharged onto the discharge tray 32.

In addition, the toner remaining on the photosensitive drum 7 after the primary transfer process is removed by the cleaning blade 10. The secondary transfer residual toner remaining on the intermediate transfer belt 18 after the secondary transfer process is removed by the belt cleaning unit 22. The toner removed by the cleaning blade 10 and the belt cleaning unit 22 is transported by the removed toner transport unit 23 and accumulated in the removed toner recovery container 24.

<Process cartridge>
Next, the process cartridge 1 which is detachably mounted in the main body 100a of the image forming apparatus 100 will be described with reference to FIGS.

Figure 1 is a cross-sectional view of the process cartridge 1 according to this embodiment. Figure 4 is a perspective view of the process cartridge 1 according to this embodiment. Figure 4(a) is a perspective view of the process cartridge 1 as viewed from the bottom side. Figure 4(b) is a perspective view of the process cartridge 1 as viewed from the top side.

Figure 1 shows the process cartridge 1 when an image forming operation is being performed. In other words, the up-down direction in Figure 1 indicates the vertical direction when an image forming operation is being performed. The left-right direction in Figure 1 indicates the horizontal direction when an image forming operation is being performed. In other words, Figure 1 shows the process cartridge 1 when it is attached to the device main body 100a and when an image forming operation is being performed. Figure 1 is also a view taken along the rotation axis A1 of the developing unit 6, which will be described later.

As described above, the process cartridge 1 has a photosensitive unit 4 and a developing unit 6. As shown in Figures 1, 3, 4(a) and 4(b), the photosensitive unit 4 and the developing unit 6 are connected to each other so that they can swing (rotate) by means of a pin 30 which serves as a connecting shaft. As shown in Figure 1, the developing unit 6 is rotatable around a rotation axis A1 relative to the photosensitive unit 4.

As shown in FIG. 3, the photoconductor unit 4 has a first support frame 5 that supports various members of the photoconductor unit 4 (e.g., the charging roller 8 and the cleaning blade 10). The photoconductor unit 4 also has a toner removal screw 15. The toner removal screw 15 rotates around an axis that extends in a direction parallel to the direction of the rotation axis A3 of the photoconductor drum 7.

As shown in FIG. 4(a) and FIG. 4(b), the photosensitive unit 4 has a drum bearing 33 (33F, 33R) that supports the photosensitive drum 7. The photosensitive unit 4 has a gear train for transmitting drive from the photosensitive drum 7 to the toner removal screw 15. The drum bearing 33R is disposed on one end side of the photosensitive unit 4 in the longitudinal direction of the photosensitive unit 4 (the same as the direction of the rotation axis A3 of the photosensitive drum 7). The drum bearing 33F is disposed on the other end side of the photosensitive unit 4 in the longitudinal direction of the photosensitive unit 4. In other words, the photosensitive unit 4 has the first support frame 5 and the drum bearing 33 (33F, 33R) as part of the first frame.

In this embodiment, the drum bearing 33 (33F, 33R) and the first support frame 5 function as a positioned portion that contacts the positioning portion of the device main body 100a. More specifically, the drum bearing 33 (33F, 33R) contacts the device main body 100a, and the position of the rotation axis A3 of the photosensitive drum 7 relative to the device main body 100a is determined in a direction perpendicular to the rotation axis A3 of the photosensitive drum 7. The first support frame 5 contacts the device main body 100a, and the photosensitive unit 4 is restricted from rotating around the rotation axis A3 of the photosensitive drum 7 relative to the device main body 100a. This determines the position of the photosensitive unit 4 relative to the device main body 100a in a direction perpendicular to the rotation axis A3 of the photosensitive drum 7. Furthermore, in this embodiment, the drum bearing 33R arranged downstream of the process cartridge 1 contacts the device main body 100a in the mounting direction of the process cartridge 1. This determines the position of the photosensitive unit 4 relative to the device body 100a in the direction of the rotation axis A3 of the photosensitive drum 7. The above positioning configuration can be modified as needed. For example, the position of the photosensitive unit 4 relative to the device body 100a in the direction of the rotation axis A3 of the photosensitive drum 7 may be determined by the first support frame 5 coming into contact with the device body 100a.

As shown in FIG. 3, the charging roller 8 is biased by a spring 36 in the direction of arrow C toward the photosensitive drum 7. In this embodiment, the charging roller 8 is rotated by the photosensitive drum 7. When the photosensitive drum 7 rotates in the direction of arrow A, the charging roller 8 rotates in the direction of arrow D.

The cleaning blade 10 has a rubber blade 10a for removing toner remaining on the surface of the photosensitive drum 7 after the primary transfer process, and a blade support member 10b for supporting the rubber blade 10a. The toner removed from the photosensitive drum 7 by the cleaning blade 10 is stored in a removed toner storage chamber 9 formed by the cleaning blade 10 and the first support frame 5. The toner stored in the removed toner storage chamber 9 is transported downstream in the mounting direction of the process cartridge 1 by a removed toner screw 15 disposed inside the removed toner storage chamber 9. The toner transported by the removed toner screw 15 is discharged from the removed toner discharge section 35 shown in FIG. 4(a) and transferred to the removed toner transport unit 23.

As shown in FIG. 3, the developing unit 6 has a developing frame 16. The developing frame 16 includes a partition wall 16d. The interior of the developing frame 16 is partitioned by the partition wall 16d into a developing chamber 16a and a toner storage chamber (developer storage chamber) 16b. The developing chamber 16a and the toner storage chamber 16b are connected by a first communication opening (first opening, opening) 16c formed in the partition wall 16d.

As shown in Figures 4(a) and 4(b), the developing unit 6 has developing bearings 34 (34F, 34R) that serve as bearing members that support the developing roller 11.

In the developing chamber 16a, the developing roller 11, the supply roller 17, and the developing blade 28 are arranged. When an image forming operation is performed, the developing roller 11 rotates in the direction of the arrow E and supplies the toner T to the photosensitive drum 7 by contacting the photosensitive drum 7. In the longitudinal direction of the developing unit 6 (the same as the direction of the rotation axis of the developing roller 11), one end side of the developing roller 11 is rotatably supported by the developing bearing 34R. In the longitudinal direction of the developing unit 6, the other end side of the developing roller 11 is rotatably supported by the developing bearing 34F. In other words, the developing unit 6 has the developing frame 16 and the developing bearing 34 (34F, 34R) as part of the second frame. In this embodiment, the developing frame 16 and the developing bearing 34 (34F, 34R) are made of resin.

Here, as shown in FIG. 4(b), the development bearing 34 (34F, 34R) has a force receiving portion 34e, which will be described later.

The supply roller (supply member) 17 is rotatably supported by the development bearings 34 (34F, 34R) so as to come into contact with the development roller 11. As shown in FIG. 3, when an image forming operation is performed, the supply roller 14 rotates in the direction of the arrow F to supply toner T to the development roller 11.

As shown in FIG. 3, the developing blade (layer thickness regulating member, regulating member) 28 is arranged so as to contact the surface of the developing roller 11. The developing blade 28 regulates the thickness of the toner layer formed on the surface of the developing roller 11.

As shown in FIG. 3, the toner storage chamber 16b is provided with a transport member 29 for transporting the toner T stored in the toner storage chamber 16b. In this embodiment, the transport member 29 also functions as a stirring member for stirring the toner T stored in the toner storage chamber 16b. The toner T stored in the toner storage chamber 16b is transported to the developing chamber 16a by the transport member 29 through the first communication opening 16c. In this embodiment, the transport member 29 is configured to transport the toner T toward the supply roller 17.

As shown in FIG. 3, the transport member 29 has a transport shaft 29a and a transport sheet 29b as a transport section. The transport shaft 29a rotates around a rotation axis parallel to the rotation axis A2 of the developing roller 11. The transport sheet 29b is flexible, and one end of the transport sheet 29b is attached to the transport shaft 29a, and the other end of the transport sheet 29b is a free end. When the transport shaft 29a and the transport sheet 29b rotate in the direction of the arrow G, the transport sheet 29b comes into contact with the inner wall of the toner storage chamber 16d and is deformed. Then, when the transport shaft 29a rotates further, the deformation of the transport sheet 29b is released. When the deformation of the transport sheet 29b is released, the toner T is transported to the developing chamber 16a.

As shown in FIG. 1, in this embodiment, when the process cartridge 1 is attached to the apparatus main body 100a, the developing chamber 16a is located above the toner storage chamber 16b. Furthermore, in this embodiment, when the developing unit 6 is in an image forming position described below, the developing chamber 16a is located above the toner storage chamber 16b. Furthermore, in this embodiment, when the developing unit 6 is in a separated position described below, the developing chamber 16a is located above the toner storage chamber 16b.

More specifically, in the horizontal direction, the positions of the developing chamber 16a and the toner storage chamber 16b at least partially overlap, and in the vertical direction, at least a portion of the developing chamber 16a is located above (directly above) at least a portion of the toner storage chamber 16b. Therefore, the transport member 29 draws up the toner in the toner storage chamber 16b and supplies it to the developing chamber 16a through the first communication opening 16c.

As shown in FIG. 4(b), the developing unit 6 has a toner receiving port 40 that receives toner T from the toner transport device 14. The toner receiving port 40 is located downstream of the developing unit 6 in the mounting direction of the process cartridge 1. An receiving port seal 45 and a movable receiving port shutter 41 are located above the toner receiving port 40. When the process cartridge 1 is not mounted in the device main body 100a, the toner receiving port 40 is closed by the receiving port shutter 41. The receiving port shutter 41 is configured to open when it is urged by the device main body 100a of the image forming apparatus 100 in conjunction with the mounting operation of the process cartridge 1.

As shown in FIG. 3, the developing unit 6 has a supply toner transport passage 42 that communicates with the toner receiving port 40, and a supply toner transport screw 43 is disposed inside the supply toner transport passage 42. Furthermore, the developing unit 6 has a second communication opening (second opening) 44 that communicates the supply toner transport passage 42 with the toner storage chamber 16b. The second communication opening 44 is disposed near the center of the developing unit 6 in the longitudinal direction of the developing unit 6.

The replenishment toner transport screw 43 extends parallel to the direction of the rotation axis of the developing roller 11, and transports the toner T received from the toner receiving port 40 to the toner storage chamber 16b through the second communication opening 44.

<Combination of photoconductor unit and developing unit>
The connection between the photoconductor unit 4 and the developing unit 6 will be described with reference to Fig. 5. Fig. 5 is an exploded perspective view showing the connection between the photoconductor unit and the developing unit according to this embodiment.

In this embodiment, the longitudinal direction of the process cartridge 1 is the same as the direction of the rotation axis A2 (second axis, development axis) of the developing roller 11 and the direction of the rotation axis A3 (third axis, image carrier axis) of the photosensitive drum 7. The longitudinal direction of the process cartridge 1 is the same as the longitudinal direction of the photosensitive unit 4 and the longitudinal direction of the developing unit 6. In the longitudinal direction of the process cartridge 1, the developing bearing 34R and the drum bearing 33R are arranged on one end side of the process cartridge 1, and the developing bearing 34F and the drum bearing 33F are arranged on the other end side. The developing roller 11 and the photosensitive drum 7 are configured to receive a driving force from the device main body 100a at one end side of the process cartridge 1. In other words, one end side of the process cartridge 1 can be called the driving side, and the other end side of the process cartridge 1 can be called the non-driving side.

As shown in FIG. 5, the first support frame 5 of the photosensitive unit 4 is provided with holes 5a, 5b, and 5c. In the longitudinal direction of the process cartridge 1, the hole 5a is located on one end side of the first support frame 5, and the holes 5b and 5c are located on the other end side of the first support frame 5.

On the other hand, the developer bearing 34F has a hole 34c. The developer bearing 34R has holes 34a and 34b.

Pins 30 are disposed on one end and the other end of the process cartridge 1. The pins 30 have a cylindrical shape including a large diameter portion and a small diameter portion. At one end of the process cartridge 1, the pins 30 engage with holes 34a, 5a, and 34b so that hole 5a is positioned between holes 34a and 34b. At the other end of the process cartridge 1, the pins 30 engage with holes 5b, 34c, and 5c so that hole 34c is positioned between holes 5b and 5c. This allows the developing unit 6 to be rotatably (swingably) connected to the photosensitive unit 4 around the center of rotation (swing center).

In this embodiment, the rotation axis (first axis, unit axis) A1 of the developing unit 6 shown in FIG. 1 coincides with the axis of the pin 30. Furthermore, in this embodiment, the direction of the rotation axis A1 of the developing unit 6 is parallel to the rotation axis A2 of the developing roller 11 and the rotation axis A3 of the photosensitive drum 7. In this embodiment, when viewed along the rotation axis A1 of the developing unit 6, the pin 30 arranged on one end side of the process cartridge 1 is coaxial with the pin 30 arranged on the other end side of the process cartridge 1. The developing unit 6 is inseparably connected to the photosensitive unit 4. Therefore, when the process cartridge 1 is removed from the apparatus main body 100a, the developing unit 6 is restricted from moving in the direction of the rotation axis A1 relative to the photosensitive unit 4. Furthermore, the developing unit 6 is allowed to rotate around the rotation axis A1 relative to the photosensitive unit 4, but is restricted from moving parallel to the direction intersecting the rotation axis A1.

<Movement of Development Unit>
The movement of the developing unit 6 relative to the photosensitive unit 4 will be described with reference to Figs. 1 and 6. Fig. 6 is a cross-sectional view illustrating the movement of the developing unit 6 according to this embodiment. Fig. 6(a) is a cross-sectional view of the process cartridge 1 when the developing unit 6 is in the separated position. Fig. 6(b) is a cross-sectional view of the process cartridge 1 when the developing unit 6 is in the image forming position. In Figs. 6(a) and 6(b), the photosensitive unit 4 is supported by the main body 100a of the apparatus and takes a posture when an image forming operation is performed. Figs. 6(a) and 6(b) are cross-sectional views of the process cartridge 1 as viewed in the direction of the rotation axis A1 of the developing unit 6, similar to Figs. 1 and 3. The up-down direction in Figs. 6(a) and 6(b) indicates the vertical direction when the photosensitive unit 4 takes a supported posture described later, and the left-right direction indicates the horizontal direction when the photosensitive unit 4 takes a supported posture.

The developing unit 6 is coupled to the photoconductor unit 4 and is configured to be rotatable about a rotation axis A1 relative to the photoconductor unit 4. As the developing unit 6 rotates about the rotation axis A1, the developing unit 6 moves between the image forming position shown in FIG. 6(b) and the separated position shown in FIG. 6(a) relative to the photoconductor unit 4.

The image forming position (first position) of the developing unit 6 can also be called the position when the developing roller 11 develops the electrostatic latent image on the photosensitive drum 7. The image forming position of the developing unit 6 can also be called the position where the distance between the developing roller 11 and the photosensitive drum 7 is the shortest. In this embodiment, when the developing unit 6 is in the image forming position, the developing roller 11 is in contact with the photosensitive drum 7. When the developing unit 6 is in the separated position (second position), the developing roller 11 is separated from the photosensitive drum 7. In other words, the separated position of the developing unit 6 can also be called the position where the distance between the developing roller 11 and the photosensitive drum 7 is longer than when the developing unit 6 is in the image forming position.

As described above, the developing unit 6 rotates around the rotation axis A1, so that the developing unit 6 takes an image forming position and a spaced position relative to the photoconductor unit 4.

When the photoconductor unit 4 is supported by the device main body 100a, the developing unit 6 is located at the separated position due to its own weight. In other words, when the photoconductor unit 4 takes the same posture (supported posture) as when it is supported by the device main body 100a, the developing unit 6 is located at the separated position due to its own weight. In other words, when the photoconductor unit 4 takes the same posture (image forming posture) as when an image forming operation is performed, the developing unit 6 is located at the separated position due to its own weight. In this embodiment, the supported posture of the photoconductor unit 4 and the image forming posture of the photoconductor unit 4 are the same. Also, in this embodiment, when the photoconductor unit 4 takes the supported posture, a part of the photoconductor drum 7 is exposed toward the top of the process cartridge 1.

The developing unit 6 does not need to be positioned at the separated position by its own weight alone. In other words, the process cartridge 1 only needs to be such that the developing unit 6 is naturally positioned at the separated position when the photoconductor unit 4 is in the supported position.

More specifically, when the weight of the developing unit 6 when the photosensitive unit 4 is in the supported position and the internal force of the process cartridge 1 are combined, the force urging the developing unit 6 toward the separated position is greater than the force urging the developing unit 6 toward the image forming position. For example, the process cartridge 1 may include a member that generates a force urging the developing unit 6 toward the separated position, or a member that generates a force urging the developing unit 6 toward the image forming position. However, in either case, when the process cartridge 1 is in a position in which the photosensitive unit 4 is in the supported position, the developing unit 6 naturally moves to the separated position. In other words, when the photosensitive unit 4 is in the supported position, the developing unit 6 moves from the image forming position to the separated position at least by its own weight.

As shown in Figures 6(a) and 6(b), the weight of the developing unit 6 (in the direction of the arrow) acts on the center of gravity Gd of the developing unit 6. When the photosensitive unit 4 is in the supported position, the weight of the developing unit 6 acting on the center of gravity Gd generates a force (moment around the rotation axis A1) in a direction in which the developing roller 11 moves away from the photosensitive drum 7.

As shown in Figures 6(a) and 6(b), when the photosensitive unit 4 is in the supported position, the center of gravity Gd is located above the horizontal line (line extending horizontally) h passing through the rotation axis A1 of the developing unit 6 in the vertical direction. Furthermore, the photosensitive drum 7, developing roller 11, supply roller 17, developing chamber 16d, and partition wall 16d are located above the horizontal line h. Furthermore, in the vertical direction, the rotation axis A2 of the developing roller 11 is located below the rotation axis A3 of the photosensitive drum 7. Also, in the vertical direction, the center of gravity Gd is located below the photosensitive drum 7, developing roller 11, supply roller 17, developing chamber 16d, and partition wall 16d.

In the horizontal direction, the center of gravity Gd is located on the opposite side of the photosensitive drum 7 with respect to a vertical line i (a line extending vertically and perpendicular to the horizontal line h) passing through the rotation axis A1 of the developing unit 6. That is, the photosensitive drum 7 is located on one side of the vertical line i, and the center of gravity Gd is located on the other side of the vertical line i. In other words, the center of gravity Gd is located at a position farther away (farther) from the photosensitive drum 7 than the vertical line i. Note that in this embodiment, the supply roller 17 is also located at a position farther away from the photosensitive drum 7 than the vertical line i, just like the center of gravity Gd. By arranging the developing unit 6 in this manner with respect to the vertical line i, it is possible to easily position the developing unit 6 in the separated position by its own weight.

Here, the natural state of the process cartridge 1 is defined as a state in which gravity and the internal force of the process cartridge 1 act on the developing unit 6, and no external forces other than gravity act on the developing unit 6. Note that if the process cartridge 1 includes a biasing member that biases the developing unit 6, the force of the biasing member is included in the above internal force.

When the photosensitive unit 4 is in the supported position and the process cartridge 1 is in its natural state, the force acting on the developing unit 6 in the direction moving the developing roller 11 away from the photosensitive drum 7 is greater than the force acting in the direction moving the developing roller 11 closer to the photosensitive drum 7. As a result, the force urging the developing unit 6 toward the separated position is greater than the force urging the developing unit 6 toward the image forming position, so the developing unit 6 is naturally positioned at the separated position.

In this embodiment, the developing unit 6 is located at the separated position due to its own weight. In other words, the weight component of the developing unit 6 in the force acting in the direction to move the developing roller 11 away from the photosensitive drum 7 is greater than the internal force of the process cartridge 1 acting in the direction to move the developing roller 11 closer to the photosensitive drum 7.

Furthermore, in this embodiment, the process cartridge 1 does not have any member that generates a force acting in a direction that brings the developing roller 11 closer to the photosensitive drum 7 (a force that urges the developing unit 6 toward the image forming position). Therefore, the magnitude of the internal force of the process cartridge 1 that acts in a direction that brings the developing roller 11 closer to the photosensitive drum 7 is zero.

In this way, when the process cartridge 1 is inserted into the apparatus main body 100a, the developing unit 6 naturally positions itself in the separated position. When no image forming operation is being performed, the developing unit 6 waits in the separated position. Therefore, even if the process cartridge 1 is left unused for a long period of time, the developing roller 11 and the photosensitive drum 7 are prevented from coming into contact with each other, and deformation of the surface of the developing roller 11 can be prevented.

Also, unlike the process cartridge 1 of this embodiment, when the developing roller 11 is brought into contact with the photosensitive drum 7 by a spring provided in the cartridge, the spring must generate a force pressing the developing roller 11 against the photosensitive drum 7 in addition to the weight of the developing unit 6. Also, in a cartridge using such a spring, when the developing unit 6 is moved in a direction in which the developing roller 11 moves away from the photosensitive drum 7, the amount of deformation of the spring increases. Therefore, the force of the spring becomes larger when the developing roller 11 leaves the photosensitive drum 7 than when the developing roller 11 contacts the photosensitive drum 7, and there is a possibility that the cartridge will be deformed. In contrast, in the configuration of this embodiment, the process cartridge 1 does not need to be provided with such a spring, and deformation of the process cartridge 1 can be reduced.

On the other hand, as shown in FIG. 6(a) and FIG. 6(b), the device main body 100a is provided with a force applying section 101 as a part of the device main body 100a. The developing unit 6 is also provided with a force receiving section 34e that comes into contact with the force applying section 101 and receives a force from the force applying section 101. The control section 100C controls the driving source 100M and controls the operation of the force applying section 101 by the driving source 100M. The force applying section 101 driven by the driving source 100M applies a force to the force receiving section 34e to move it during image formation, and moves away from the force receiving section 34e during non-image formation (including the mounting and dismounting operation of the process cartridge 1). The contact operation and separation operation of the developing roller 11 caused by the movement of the force applying section 101 is preferably performed while the photosensitive drum 7 is rotating, and more preferably while the photosensitive drum 7 and the developing roller 11 are rotating.

The force receiving portion 34e is a protrusion that protrudes in a direction perpendicular to the rotation axis A1 and away from the rotation axis A1, and is configured to come into contact with the force applying portion 101 at the apex of the protrusion. In this embodiment, the apex of the protrusion is a curved surface. This makes it easier to keep the position where the force applying portion 101 and the force receiving portion 34e come into contact constant. Therefore, the force applying portion 101 can stably press the force receiving portion 34e.

In the direction of the rotation axis A2 of the developing roller 11, the force receiving portion 34e is disposed at both ends of the developing unit 6. In this embodiment, the force receiving portion 34e is provided on the developing bearings 34R and 34F having a support portion that supports the developing roller 11 (see FIG. 4B). In this embodiment, the position of the support portion that supports the developing roller 11 and the position of the force receiving portion 34e are arranged so as to overlap with each other in the direction of the rotation axis A1 of the developing unit 6. This allows the force applying portion 101 to efficiently press the developing roller 11 against the photosensitive drum 17. In addition, by providing the force receiving portion 34e on the part (developing bearings 34R and 34F) that supports the developing roller 11, the positional accuracy of the force receiving portion 34e relative to the developing roller 11 can be increased. Furthermore, in this embodiment, since the distance between the developing roller 11 and the force receiving portion 34e is short as described later, the positional accuracy of the force receiving portion 34e relative to the developing roller 11 can be easily increased.

The force application section 101 is configured to be movable in a direction away from the developing unit 6 (retraction direction, arrow V direction) and a direction toward the developing unit 6 (pressure direction, arrow U direction). The force application section 101 is movable between a position away from the force receiving section 34e of the developing unit 6 (Figure 6(a)) and a position in contact with the force receiving section 34e of the developing unit 6 (Figure 6(b)). The force receiving section 34e receives a force from the force application section 101, so that the developing unit 6 is positioned at the image forming position.

As shown in FIG. 6(b), when an image forming operation is performed, the force application portion 101 moves in the pressure application direction and comes into contact with the force receiving portion 34e. The force receiving portion 34e receives a force from the force application portion 101, and the developing unit 6 rotates in the direction of the arrow M around the pin 30 (rotation axis A1). This positions the developing unit 6 at the image forming position. At this time, the developing roller 11 comes into contact with the photosensitive drum 7.

As shown in FIG. 6(a), when the image forming operation is completed, the force applying portion 101 moves in the retracting direction and moves away from the force receiving portion 34e. The weight of the developing unit 6 causes the developing unit 6 to rotate around the pin 30 (rotation axis A1) in the direction of the arrow N. This positions the developing unit 6 in the separated position. At this time, the developing roller 11 is away from the photosensitive drum 7.

As described above, the developing unit 6 moves from the image forming position to the separated position due to its own weight. Therefore, when the developing unit 6 is positioned at the image forming position and the force applying portion 101 moves in the direction of arrow V, the developing unit 6 naturally (automatically) moves toward the separated position. Then, the force applying portion 101 moves away from the force receiving portion 34e, and the developing unit 6 is positioned at the separated position.

As described above, the movement of the developing unit 6 from the image forming position to the separated position does not have to be performed only by its own weight. In other words, as described below, the process cartridge 1 may have a biasing member 50 that biases the developing unit 6 from the image forming position toward the separated position.

Since the developing unit 6 is naturally positioned at the separated position, the force application portion 101 of the device main body 100a can be separated from the process cartridge 1 when an image forming operation is not being performed. In other words, the force application portion 101 of the device main body 100a can be prevented from receiving force from the process cartridge 1 when an image forming operation is not being performed. This can therefore prevent deformation of the force application portion 101 and the parts that support it. Generally, the period when an image forming operation is not being performed is longer than the period when an image forming operation is performed, so the configuration of this embodiment can effectively prevent deformation of the force application portion 101 and the parts that support it.

<Arrangement of force receiving parts>
The arrangement of the force receiving portion 34e in the present invention will be described with reference to Fig. 1, Fig. 6(a) and Fig. 6(b). As described above, Fig. 1 is a cross-sectional view of the process cartridge 1 when the developing unit 6 is in the image forming position. In Fig. 1, the photosensitive unit 4 is supported by the apparatus main body 100a and is in a position for performing an image forming operation. Fig. 1 is a view of the process cartridge 1 as viewed along the rotation axis A1 of the developing unit 6.

As shown in FIG. 1, the force receiving portion 34e and the developing roller 11 are disposed above a horizontal line h that passes through the rotation axis A1 of the developing unit 6.

As shown in FIG. 1, the distance between the rotation axis A1 of the developing unit 6 and the rotation axis A2 of the developing roller 11 in the direction perpendicular to the rotation axis A1 of the developing unit 6 is d1 (second distance). The distance between the rotation axis A1 of the developing unit 6 and the force receiving portion 34e (the portion in contact with the force applying portion 101) is d2 (third distance). The distance between the force receiving portion 34e and the rotation axis A2 of the developing roller 11 is d3 (first distance). Note that d1, d2, and d3 are the same as the length of the straight line connecting the respective points (the rotation axis A1 of the developing unit 6, the rotation axis A2 of the developing roller 11, and the force receiving portion 34e). In this embodiment, the direction perpendicular to the rotation axis A1 of the developing unit 6 is the same as the direction perpendicular to the rotation axis A2 of the developing roller 11.

Here, in order to suppress deformation of the force application portion 101, the force receiving portion 34e, or the surrounding area, it is preferable that the force applied by the force application portion 101 to the force receiving portion 34e is small. In order to reduce the force with which the application portion 101 presses the force receiving portion 34e while ensuring the force necessary to maintain the development unit 6 in the image forming position, it is preferable that d2 is long.

On the other hand, in order to reliably separate the developing roller 11 from the photosensitive drum 7 even when the amount of rotation of the developing unit 6 is small, it is preferable that d1 is long. In particular, when d2 is long, the distance that the force receiving portion 34e moves when the developing unit 6 rotates increases. Therefore, in order to shorten the distance that the force applying portion 101 and the force receiving portion 34e move, it is preferable that the amount of rotation of the developing unit 6 is small.

In other words, d1 and d2 are determined taking into consideration the magnitude of the force applied to the force receiving portion 34e or the rotation angle of the developing unit 6. On the other hand, in the direction perpendicular to the rotation axis A1 of the developing unit 6, in order to reduce the area occupied by the process cartridge 1 in the image forming device 100, it is preferable to reduce the arrangement space of the developing roller 11, the rotation axis A1, and the force receiving portion 34e.

Therefore, it is preferable that d3 (the distance between the rotation axis A2 of the developing roller 11 and the force receiving portion 34e) is shorter than the longer of d1 and d2. It is even more preferable that d3 is shorter than d1 and d2.

In this embodiment, when the angle between d1 and d2 is θ, they are arranged so that θ<60 degrees. With this arrangement, d3 is shorter than the longer distance between d1 and d2.

In the process cartridge 1 of this embodiment, d3 is shorter than d1. Also, d3 is shorter than d2. In other words, the developing roller 11, the rotation axis A1, and the force receiving portion 34e are arranged so that d3<d1 and d3<d2. Also, in this embodiment, the developing roller 11, the rotation axis A1, and the force receiving portion 34e are arranged so that d1<d2.

In order to reduce the space required for arranging the developing roller 11, the rotation axis A1, and the force receiving portion 34e, when viewed along the rotation axis A1, the angle θ between the straight line (first straight line) connecting the rotation axis A1 and the rotation axis A2 of the developing roller 11 and the straight line (second straight line) connecting the rotation axis A1 and the force receiving portion 34e is smaller than 60°. Furthermore, it is preferable that θ is smaller than 45°. It is even more preferable that θ is smaller than 30°. In this embodiment, θ is smaller than 30°.

Furthermore, in this embodiment, both the force receiving portion 34e and the developing roller 11 are positioned above the horizontal line passing through the rotation axis A1. This allows d1 and d2 to be long. Therefore, the biasing force of the force applying portion 101 can be reduced.

When viewed along the rotation axis A1, the force receiving portion 34e is provided on the opposite side of the pin 30 (opposite side of the rotation axis A1) with respect to a line n passing through the rotation axis A3 of the photosensitive drum 7 and the rotation axis A2 of the developing roller 11. In other words, the line n is arranged so that it passes between the rotation axis A1 and the force receiving portion 34e. This makes it possible to reduce the space required to arrange the force receiving portion 34e, the developing roller 11, and the rotation axis A1 while reducing the pressing force of the force applying portion 101.

Also, as shown in Figures 6(a) and 6(b), the force receiving portion 34e is positioned so that the position of the force receiving portion 34e overlaps the position of the photosensitive drum 7 in the vertical direction.

The above-described configuration allows the space required for the process cartridge 1 to be reduced in the direction perpendicular to the rotation axis A1. In addition, the force of the force application portion 101 (the force received by the force receiving portion 34e) can be reduced. In other words, the developing unit 6 can be positioned at the image forming position with a small force. Furthermore, even if the rotation angle of the developing unit 6 is small, the developing roller 11 can be reliably separated from the photosensitive drum 7.

Furthermore, the force receiving portion 34e is disposed above the lowermost portion 16d1 of the partition wall 16d. In other words, the position of the developing chamber 16a and the position of the force receiving portion 34e overlap in the vertical direction.

The device main body 100a may be fitted with the process cartridge 1 and another process cartridge with a different volume of the toner storage chamber 16b than the process cartridge 1. By arranging the force receiving portion 34e as described above, the force applying portion 101 can be arranged at the same position even when a process cartridge with a different size of the toner storage chamber 16b is attached. In addition, compared to a configuration in which the force receiving portion 34e is arranged below the developing chamber 16a, for example, the degree of freedom in changing the shape of the toner storage chamber 16b is improved. In other words, in the portion below the force receiving portion 34e, the shape of the developing frame 16 that forms the toner storage chamber 16d can be freely changed according to the volume of the toner storage chamber 16b without being restricted by the arrangement of the force receiving portion 34.

<Positional relationship between rotation axis and center of gravity of developing unit>
Next, the positional relationship between the rotation axis A1 of the developing unit 6 and the center of gravity Gd will be described with reference to FIG.

Figure 7 is a schematic diagram showing the positional relationship between the rotation axis A1 of the developing unit 6 and the center of gravity Gd of the developing unit 6. Figure 7(a) is a diagram showing a state in which the center of gravity of the developing unit 6 is located below a horizontal line passing through the rotation axis A1 of the developing unit 6. Figure 7(b) is a diagram showing a state in which the center of gravity of the developing unit 6 is located above a horizontal line passing through the rotation axis A1 of the developing unit 6.

Figures 7(a) and 7(b) are views seen in the direction of the rotation axis A1 of the developing unit 6. In Figures 7(a) and 7(b), the M direction indicates the rotation direction of the developing unit 6, which is the direction in which the developing roller 11 approaches the photosensitive drum 7.

As shown in Figures 7(a) and 7(b), when the developing unit 6 is in the separated position, the center of gravity Gd is located at a position W away from the rotation axis A1 in the horizontal direction. When the developing unit 6 rotates in the M direction, the center of gravity Gd also rotates in the M direction. Here, as shown in Figure 7(a), if the center of gravity Gd is below the horizontal line passing through the rotation axis A1, when the developing unit 6 rotates in the M direction, the center of gravity Gd moves in a direction away from the rotation axis A1 in the horizontal direction. As a result, the distance W between the rotation axis A1 and its own weight Gd becomes longer in the horizontal direction, and the moment with which the developing unit 6 rotates in the separated direction (opposite the M direction) due to its own weight increases.

On the other hand, as shown in FIG. 7(b), if the center of gravity Gd is above the horizontal line passing through the rotation axis A1, when the developing unit 6 rotates in the M direction, the center of gravity Gd moves horizontally toward the rotation axis A1. As a result, the distance W between the rotation axis A1 and its own weight Gd becomes shorter in the horizontal direction, and the moment with which the developing unit 6 rotates in the separating direction (opposite the M direction) due to its own weight decreases.

In other words, by positioning the center of gravity Gd above the horizontal line passing through the rotation axis A1, it is possible to suppress loss due to the weight of the developing unit 6 when the developing roller 11 is brought into contact with the photosensitive drum 7. Therefore, the biasing force of the force application portion 101 can be reduced. Even if the center of gravity Gd is below the horizontal line passing through the rotation axis A1, the higher the position of the center of gravity Gd, the more gradual the increase in distance W, making it possible to reduce loss due to the weight of the developing unit 6.

Therefore, it is preferable to position the center of gravity Gd relatively high with respect to the rotation axis A1 of the developing unit 6. Therefore, in the process cartridge 1, it is preferable that the rotation axis A1 of the developing unit 6 is positioned at a low position. Also, in the process cartridge 1, it is preferable that the center of gravity Gd is positioned at a high position.

<Layout of developing chamber>
The arrangement of the developing chamber 16a in the present invention will be described with reference to FIG.

As shown in FIG. 6(b), when the developing unit 6 is in the image forming position, the developing chamber 16a is divided by a vertical line i passing through the center of the pin 30 (rotation axis A1). At this time, the volume of the portion farther from the photosensitive drum 7 than the vertical line i is greater than the volume of the portion closer to the photosensitive drum 7 than the vertical line i.

More specifically, the developing chamber 16a is divided into a first region S1 and a second region S2 by a vertical line i. The first region S1 is an region located on the opposite side of the photosensitive drum 7. The second region S2 is an region located on the same side as the photosensitive drum 7. In other words, the second region S2 is located closer to the photosensitive drum 7 than the first region S1. The developing chamber 16a is positioned such that the first region S1 is larger than the second region S2. In other words, the developing chamber 16a is positioned such that the volume of the first region S1 is larger than the volume of the second region S2.

The toner transported from the toner storage chamber 16b by the transport member 29 accumulates in the developing chamber 16a. More specifically, the toner transported from the toner storage chamber 16b accumulates in the gap m between the supply roller 17 arranged in the developing chamber 16a and the bottom surface 16d1 of the partition wall 16d.

Here, in the developing unit 6 of this embodiment, the developing chamber 16a is arranged so that the volume of the first region S1 is larger than the volume of the second region S2. Therefore, the amount of toner that accumulates in the first region S1 is greater than the amount of toner that accumulates in the second region S2. As a result, when the force applying portion 101 moves in the direction of the arrow V, the weight of the toner that has accumulated in the first region S1 of the developing chamber 16a acts as a moment in a direction in which the developing roller 11 moves away from the photosensitive drum 7. This makes it possible to more reliably separate the developing roller 11 due to the weight of the developing unit 6 itself. In other words, the developing unit 6 can be more easily positioned at the separation position due to its own weight.

Furthermore, by storing toner in the developing chamber 16a located above the toner storage chamber 16b, even if the toner in the developing unit 6 decreases, the toner can be stored at a high position in the developing unit 6. Therefore, the weight of the toner can be concentrated at a high position in the developing unit 6.

When the developing unit 6 is in the image forming position, the toner storage chamber 16b is divided by a horizontal line h passing through the rotation axis A1. At this time, the volume of the portion located above the horizontal line h is larger than the volume of the portion located below the horizontal line h.

More specifically, the area above the horizontal line is the third area S3, and the area below the horizontal line is the fourth area S4. In other words, the fourth area is located below the third area. At this time, the toner storage chamber 16b is configured so that the volume of the third area S3 is larger than the volume of the fourth area S4. This allows the center of gravity Gd of the developing unit 6 to be kept at a high position even if the amount of toner stored in the toner storage chamber 16b decreases. In this embodiment, the center of gravity Gd of the developing unit 6 can be located above the horizontal line h passing through the rotation axis A1 even if the amount of toner stored in the toner storage chamber 16b decreases.

As shown in Figures 1 and 6(b), the developing unit 6 at the image forming position is divided into a first portion and a second portion located below the first portion by a horizontal line h passing through the rotation axis A1. The first portion is the portion above the horizontal line h, and the second portion is the portion below the horizontal line h. In this case, the first portion is larger than the second portion. Also, the first portion is heavier than the second portion.

<Relationship between the rotation axis of the developing roller and the developing unit>
The rotation axis A1 of the developing unit 6 and the arrangement of the developing roller 11 will be described with reference to FIG.

As shown in FIG. 6(a) and FIG. 6(b), in this embodiment, the developing roller 11 and the supply roller 17 are arranged above the pin 30. The developing roller 11 has a rubber layer 11a as an elastic layer and a first metal shaft 11b arranged inside the rubber layer 11a. The supply roller 17 has a sponge layer 17a and a second metal shaft 17b arranged inside the sponge layer 17a. The sponge layer 17a is deformed by the reaction force received from the developing roller 11. In this embodiment, when the developing unit 6 is in the image forming position, the rubber layer 11a is deformed by the reaction force received from the photosensitive drum 7. In addition, the first shaft 11b and the second shaft 17b are metal shafts supported by the developing bearings 34 (34F, 34R). The developing roller 11 is heavier than the supply roller 17. Therefore, the proportion of the weight of the developing unit 6 that the developing roller 11 occupies is greater than the proportion that the supply roller 17 occupies. Additionally, the maximum diameter of the first shaft 11b is larger than the maximum diameter of the second shaft 17b. Furthermore, in this embodiment, the first shaft 11b is the heaviest metal part among the metal parts included in the developing unit 6.

In this embodiment, when the photoconductor unit 4 is in the supported position and the development unit 6 is in the image forming position, the development roller 11 is positioned so as to overlap with the vertical line i. Also, in this embodiment, when the photoconductor unit 4 is in the supported position and the development unit 6 is in the separated position, the development roller 11 is positioned so as to overlap with the vertical line i.

As described above, the developing unit 6 is positioned in the separated position by its own weight. On the other hand, in order to position the developing unit 6 in the image forming position, the force applying portion 101 needs to bias the force receiving portion 34e. In other words, if the effect of the developing unit 6's own weight is too large, the load on the force applying portion 101 increases. On the other hand, if the effect of the developing unit 6's own weight is too small, the developing unit 6 cannot be stably separated.

Therefore, the developing roller 11 is arranged so as to overlap the vertical line i passing through the rotation center A1. In particular, in this embodiment, the developing roller 11 is arranged so as to overlap the first shaft 11b of the developing roller 11. As shown in FIG. 6(a), when the developing unit 6 is in the separated position, the vertical line i overlaps the first shaft 11b. This makes it possible to reduce the influence of the weight of the developing roller 11 when the developing unit 6 is in the separated position. Also, as shown in FIG. 6(b), when the developing unit 6 is in the image forming position, the vertical line i overlaps the first shaft 11b. This makes it possible to reduce the influence of the weight of the developing roller 11 when the developing unit 6 is in the image forming position. In other words, in a configuration in which the developing unit 6 is positioned in the separated position at least by its own weight, it is possible to prevent the force that moves the developing unit 6 toward the separated position from becoming too large. Therefore, the force applying section 101 of the device main body 100a can position the developing unit 6 in the image forming position with a small force.

In this embodiment, by arranging the developing roller 11, which is heavier than the supply roller 17, as described above, it is possible to reduce the influence of parts that contribute greatly to the force in the direction in which the developing unit 6 separates.

Furthermore, in this embodiment, when the developing unit 6 is in the image forming position, the rotation axis A2 of the developing roller 11 is positioned closer to the photosensitive drum 7 than the vertical line i. When the developing unit 6 is in the separated position, the rotation axis A2 of the developing roller 11 is positioned farther from the photosensitive drum 7 than the vertical line i. As a result, when the developing unit 6 is in the image forming position, the weight of the developing roller 11 can be made to act in a direction in which the developing roller 11 approaches the photosensitive drum 7. On the other hand, when the developing unit 6 is in the separated position, the weight of the developing roller 11 can be made to act in a direction in which the developing roller 11 moves away from the photosensitive drum 7.

<Assistance for separation operation>
Assistance of the separating operation of the developing unit 6 will be described with reference to Fig. 8. Fig. 8 is a side view of the process cartridge 1 according to this embodiment. Fig. 8 is a side view of the process cartridge 1 as viewed in the direction of the rotation axis A1 of the developing unit 6.

As described above, in this embodiment, the developing unit 6 is positioned at least by its own weight from the image forming position to the separated position so that the developing roller 11 moves away from the photosensitive drum 7. However, the movement of the developing unit 6 from the image forming position to the separated position does not have to be performed only by its own weight. In other words, the process cartridge 1 may have a biasing member 50 that biases the developing unit 6 from the image forming position toward the separated position. In other words, the biasing member 50 assists the developing unit 6 to move by its own weight. Note that in this embodiment, the developing unit 6 is in contact with the regulating portion 5d, which is part of the first support frame 5, at the separated position. This restricts the developing unit 6 from moving in the direction in which the developing roller 11 moves away from the photosensitive drum 7.

The urging member 50 is intended to assist the movement of the developing unit 6, so it is not necessary to generate a strong force that would deform parts of the developing unit 6 or the photosensitive unit 4. In this embodiment, when the photosensitive unit 4 takes a posture that is vertically opposite to the supported posture (a posture inverted from the top to bottom in FIG. 1), the developing unit 6 is positioned at the image forming position by its own weight, resisting the urging force of the urging member 50. In other words, the developing roller 11 is allowed to come into contact with the photosensitive drum 7.

The process cartridge 1 does not need to be equipped with a biasing member 50. In other words, when the photosensitive unit 4 is in the supported position, the developing unit 6 may be configured to be positioned in the separated position only by its own weight.

As described above, the image forming apparatus 100 in this embodiment performs image formation operation by the so-called contact development method. However, the present invention is not limited to the contact development method. The present invention can also be applied to an image forming apparatus that performs image formation operation with a gap formed between the photosensitive drum 7 and the developing roller 11 when the developing unit 6 is in the image forming position. In this configuration, when the developing unit 6 is in the image forming position, the developing roller 11 is located close to the photosensitive drum 7.

REFERENCE SIGNS LIST 1 process cartridge 4 photosensitive unit 5 first support frame 6 developing unit 7 photosensitive drum 11 developing roller 16 developing frame 16a developing chamber 16b toner storage chamber 16c first communication opening 16d partition wall 17 supply roller 29 transport member 30 pin 33 (33F, 33R) drum bearing 34 (34F, 34R) developing bearing 50 biasing member 100 image forming apparatus 100a apparatus main body 101 force applying portion h horizontal line i vertical line A1 rotation axis

Claims (24)

A cartridge to be mounted in a main body of an image forming apparatus for performing an image forming operation,
a first unit including a photoconductor;
a second unit coupled to the first unit and including a developer carrier and a force receiving portion, the second unit being rotatable about a first axis so as to move relative to the first unit between a first position where the developer carrier contacts the photoconductor and a second position where the developer carrier is separated from the photoconductor, and being configured to be located at the first position when the force receiving portion receives a force from the device main body;
having
the second unit is configured to be located at the second position by its own weight when the first unit is in the same position as when the image forming operation is performed, and the developer carrier and the force receiving portion are located above a horizontal line passing through the first axis;
the developer carrier is configured to be rotatable about a second axis;
When viewed in the direction of the first axis, a first distance between the force receiving portion and the second axis is shorter than a second distance between the first axis and the second axis and a third distance between the first axis and the force receiving portion. The cartridge according to claim 1, characterized in that the center of gravity of the second unit is located above the horizontal line and is located at a position farther from the photosensitive body than a vertical line passing through the first axis. The cartridge according to claim 2, characterized in that, when the first unit is in the same position as when the image forming operation is performed, the center of gravity is located below the developer carrier. A cartridge according to any one of claims 1 to 3, characterized in that, when the first unit is in the same position as when the image forming operation is performed and the second unit is in the first position, and the second unit is divided by the horizontal line into a first portion and a second portion located below the first portion, the first portion is heavier than the second portion. A cartridge to be mounted in a main body of an image forming apparatus,
a first unit including a photoconductor and configured to be supported by the main body of the apparatus;
a second unit coupled to the first unit and including a developer carrier and a force receiving portion, the second unit being rotatable about a first axis so as to move relative to the first unit between a first position where the developer carrier contacts the photoconductor and a second position where the developer carrier is separated from the photoconductor, and being configured to be located at the first position when the force receiving portion receives a force from the device main body;
having
the second unit is configured to be located at the second position by its own weight in a state in which the first unit is supported by the apparatus main body, and the developer carrier and the force receiving portion are located above a horizontal line passing through the first axis;
The cartridge is characterized in that the developer carrier is configured to be rotatable around a second axis, and in a direction perpendicular to the first axis, a first distance between the force receiving portion and the second axis is shorter than a second distance between the first axis and the second axis and a third distance between the first axis and the force receiving portion. The cartridge according to claim 5, characterized in that the center of gravity of the second unit is located above the horizontal line and at a position farther from the photosensitive body than a vertical line passing through the first axis. The cartridge according to claim 6, characterized in that, when the first unit is supported by the device body, the center of gravity is located below the developer carrier. A cartridge according to any one of claims 5 to 7, characterized in that, when the first unit is supported by the device body and the second unit is located at the first position, and the second unit is divided by the horizontal line into a first portion and a second portion located below the first portion, the first portion is heavier than the second portion. A cartridge according to any one of claims 1 to 8, characterized in that the second unit has a bearing member that supports the developer carrier, and the force receiving portion is provided on the bearing member. the bearing member has a support portion that supports the developer carrier,
10. A cartridge according to claim 9, wherein the position of the force receiving portion overlaps the position of the support portion in the direction of the first axis. A cartridge according to any one of claims 1 to 10, characterized in that, when viewed in the direction of the first axis, an angle between a first straight line connecting the first axis and the second axis and a second straight line connecting the first axis and the force receiving portion is smaller than 60°. The cartridge of claim 11, wherein the angle is less than 30°. The cartridge according to any one of claims 1 to 12, characterized in that the force receiving portion is a protruding portion that protrudes in a direction perpendicular to the first axis and away from the first axis, and is configured so that the apex of the protruding portion comes into contact with the device body. A cartridge according to any one of claims 1 to 13, characterized in that the photosensitive member is configured to be rotatable around a third axis. The cartridge according to claim 14, characterized in that, when viewed in the direction of the first axis, the force receiving portion is arranged such that a straight line passing through the second axis and the third axis passes between the force receiving portion and the first axis. A cartridge according to claim 14 or 15, characterized in that the developer carrier is located below the third axis. A cartridge according to any one of claims 14 to 16, characterized in that it is detachable from the device body along the direction of the third axis. A cartridge according to any one of claims 1 to 17, characterized in that the force receiving portion is arranged so that the position of the force receiving portion overlaps the position of the photosensitive body in the vertical direction. the second unit has a developing frame, the developing frame divides an interior of the developing frame into a developer accommodating chamber that accommodates a developer and a developing chamber in which the developer carrier is disposed, and has a partition wall having an opening that communicates between the developer accommodating chamber and the developing chamber;
19. A cartridge according to claim 1, wherein the force receiving portion is disposed so that a position of the force receiving portion overlaps a position of the developing chamber in the vertical direction. The cartridge according to claim 19, characterized in that at least a portion of the developing chamber is located directly above at least a portion of the developer storage chamber. The cartridge according to claim 19 or 20, characterized in that the developer storage chamber has a transport member for transporting developer from the developer storage chamber to the developing chamber. A cartridge according to any one of claims 1 to 21, characterized in that it is provided with a biasing member that biases the second unit toward the second position. The device body;
A cartridge according to any one of claims 1 to 22;
an exposure device for forming an electrostatic latent image on the photoconductor, a force application unit that applies force to the force receiving unit and moves the force receiving unit; and a drive source that drives the force application unit;
24. The image forming apparatus according to claim 23, further comprising a control unit that controls an operation of the force application unit by the driving source.

Images