HK40020798A

HK40020798A - Process cartridge and image formation device

Info

Publication number: HK40020798A
Application number: HK42020010466.9A
Authority: HK
Inventors: Maeshima Hideki; Hirukawa Kuniaki; Gofuku Shuichi; Mitsui Yoshihiro
Original assignee: Canon Kabushiki Kaisha
Priority date: 2012-12-14
Filing date: 2015-10-28
Publication date: 2020-10-30

Description

Process cartridge and image forming apparatus

The present application is a divisional application of an invention patent application having an application date of 2013, 12 and 13, and an application number of 201380070338.8 (international application number PCT/JP2013/084174), an invention name of "process cartridge and image forming apparatus".

Technical Field

The present invention relates to a process cartridge detachably mountable to an image forming apparatus and an image forming apparatus including the process cartridge. The image forming apparatus forms an image on a recording material using an image forming process. Examples of the image forming apparatus include a printer, a copying machine, a facsimile machine, or a word processor and a multifunction machine of these machines.

Background

Generally, in an image forming apparatus using an electrophotographic image forming process, a photosensitive drum and a process member capable of acting on the photosensitive drum are not fixed in a cartridge. Further, a process cartridge of a type detachably mountable to an apparatus main assembly of an image forming apparatus is employed.

According to this type of process cartridge, maintenance of the image forming apparatus can be performed by the user himself. As a result, operability can be significantly improved and this type of process cartridge is widely used in image forming apparatuses.

In a full-color electrophotographic image forming apparatus using a transfer belt (intermediate transfer belt), a configuration is used in which a plurality of process cartridges are arranged below the transfer belt. This is because in the case of the configuration in which the printed product is discharged onto the upper surface of the image forming apparatus by disposing the process cartridge below the transfer belt, the first printing time can be shortened. As a process cartridge corresponding to such a configuration, a configuration is used in which a developing chamber is disposed at an upper portion close to a transfer belt and developer is drawn up into the developing chamber from a developer accommodating chamber disposed below the developing chamber (japanese laid-open patent application 2008-.

In such a process cartridge, the circulation of the developer in the developing chamber is improved by providing the agitating member in the developing chamber, so that the developer is efficiently supplied to the developing roller above the developing chamber to reduce the amount of the remaining developer.

However, in the configuration of japanese laid-open patent application 2008-170951, it is necessary to provide an agitating member in the developing chamber in a side of the developing chamber below the contact portion between the developing roller and the developer supply roller. Therefore, the developer supply roller for supplying the developer to the developing roller is rotated in the rotation direction opposite to the rotation direction of the developing roller, so that the circulation of the developer is equal to or greater than the conventional level in the case where the agitating member is not provided in the developing chamber, and the supply performance of the developer from the developer supply roller to the developing roller can be satisfied. According to this configuration, a space that is normally secured for arranging the agitating member can be filled and thus the surplus of the developer can be further suppressed.

The present invention is a further development of the prior art structure.

Disclosure of Invention

Therefore, an object of the present invention is to provide a process cartridge and an image forming apparatus in which, with a configuration in which developer is drawn up from a developer accommodating chamber provided below a developing chamber to the developing chamber above the developer accommodating chamber, the remaining developer can be reduced while reducing the number of components.

According to the present invention, there is provided a process cartridge comprising: (i) a photosensitive drum; (ii) a rotatable developing roller for developing an electrostatic latent image formed on the photosensitive drum; (iii) a developer supply roller disposed in contact with the developing roller to supply a developer to the developing roller; (iv) a driving force receiving portion for receiving a driving force, wherein the driving force receiving portion is provided at an axial end portion of the developer supply roller and is movable in a direction intersecting an axis of the developer supply roller; (v) a first driving force transmitting portion for transmitting the driving force received by the driving force receiving portion to the developing roller, wherein the first driving force transmitting portion is provided on the developer supplying roller; and (vi) a second driving force transmitting portion provided on the developing roller and configured to transmit a driving force by engagement with the first driving force transmitting portion, wherein a rotational direction of the developing roller is a direction opposite to a rotational direction of the developer supplying roller, and a surface speed of the developer supplying roller is greater than a surface speed of the developing roller.

Further, according to the present invention, there is provided an image forming apparatus including a main assembly and a process cartridge, comprising: (i) the main assembly including (i-i) a driving portion; and (ii) the process cartridge detachably mountable to the image forming apparatus, the process cartridge comprising: (ii-i) a photosensitive drum; (ii-ii) a rotatable developing roller for developing an electrostatic latent image formed on the photosensitive drum; (ii-iii) a developer supply roller provided in contact with the developing roller and for supplying the developer to the developing roller; (ii-iv) a driving force receiving portion for receiving a driving force by being connected with the driving portion, wherein the driving force receiving portion is provided at an axial end portion of the developer supply roller and is movable in a direction crossing an axis of the developer supply roller; (ii-v) a first driving force transmitting portion for transmitting the driving force received by the driving force receiving portion to the developing roller, wherein the first driving force transmitting portion is provided on the developer supplying roller; and (ii-vi) a second driving force transmitting portion provided on the developing roller and for transmitting a driving force from the first driving force transmitting portion to the developing roller by engaging with the first driving force transmitting portion, wherein a rotational direction of the developing roller is opposite to a rotational direction of the developer supplying roller, and a surface speed of the developer supplying roller is greater than a surface speed of the developing roller.

Drawings

Fig. 1 is a schematic view showing a drive input portion and a drive system of a developing unit in an embodiment of the present invention;

fig. 2 is a main sectional view of an image forming apparatus in an embodiment of the present invention;

fig. 3 is a main sectional view of the process cartridge in the embodiment of the present invention;

fig. 4 is a general perspective view of a process cartridge in an embodiment of the present invention;

FIG. 5 is a general perspective view of a developing unit in an embodiment of the invention;

fig. 6 is a schematic view of mounting the process cartridge into the image forming apparatus in the embodiment of the present invention;

in fig. 7, partial views (a) to (d) are schematic views for illustrating an operation of mounting the process cartridge in the image forming apparatus main assembly in the embodiment of the present invention;

fig. 8 is a perspective view showing a state in which the process cartridge is positioned to the main assembly of the image forming apparatus in the embodiment of the present invention;

fig. 9 is a sectional view for illustrating an interval operation of the developing unit in the embodiment of the present invention;

fig. 10 is a sectional view for illustrating a contact operation of the developing unit in the embodiment of the present invention;

fig. 11 is a perspective view of the process cartridge before it is mounted in the main assembly of the image forming apparatus in the embodiment of the present invention;

fig. 12 is a perspective view of the process cartridge mounted in the main assembly of the image forming apparatus in the embodiment of the present invention;

fig. 13 includes a schematic view of an operation of mounting the process cartridge in the image forming apparatus main assembly as viewed from the apparatus main assembly front side in the embodiment of the present invention;

fig. 14 includes a schematic view of the position at which the process cartridge is mounted in the image forming apparatus main assembly as viewed from the apparatus main assembly side surface side in the embodiment of the present invention;

fig. 15 is a perspective view for illustrating a supporting configuration of the toner supplying roller and the developing roller in the embodiment of the present invention;

FIG. 16 is an exploded view of a shaft coupling member in an embodiment of the present invention;

FIG. 17 includes a cross-sectional schematic view of a shaft coupling member in an embodiment of the present invention;

fig. 18 is a perspective view for illustrating first and second main assembly driving members of the main assembly of the image forming apparatus and a shaft coupling member in a developing unit state in the embodiment of the present invention;

fig. 19 is a schematic view showing a configuration of a developing chamber in the embodiment of the present invention;

fig. 20 is a schematic view showing a drive gear train of the developing unit in the embodiment of the present invention;

fig. 21 is a schematic view showing a slight deformation of the sponge portion in the embodiment of the invention;

fig. 22 is a schematic view showing a case where a developing driving force is input to a developing roller shaft;

fig. 23 includes a schematic view showing teeth of gears in such a configuration that the developing driving force is input to the developing roller shaft;

FIG. 24 is a schematic view showing teeth of a gear in an embodiment of the invention;

fig. 25 is a graph showing the level of the relationship between the peripheral speed difference and the image or the like in the embodiment of the invention;

fig. 26 is a schematic diagram illustrating a comparative example in which a developing chamber toner supplying member is provided in a developing chamber.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described exemplarily and specifically with reference to the accompanying drawings. However, the sizes, materials, shapes, relative arrangements, and the like of constituent elements described in the following embodiments are appropriately changed depending on the configuration of an apparatus (device) to which the present invention is applied or various conditions. Accordingly, the invention is not limited thereto unless otherwise specified.

Hereinafter, an image forming apparatus and a process cartridge used in the image forming apparatus according to an embodiment of the present invention will be described in accordance with the drawings.

(Overall Structure of image Forming apparatus)

First, the overall structure of an electrophotographic image forming apparatus (hereinafter referred to as an "image forming apparatus") 100 will be described using fig. 2. As shown in fig. 2, four detachably mountable process cartridges 70(70Y, 70M, 70C, 70K) are detachably mounted by mounting members (not shown). Further, an upstream side of the process cartridge 70 with respect to the mounting direction to the image forming apparatus 100 is defined as a front (surface) side, and a downstream side of the process cartridge 70 with respect to the mounting direction is defined as a rear (surface) side. In fig. 2, the respective process cartridges 70 are inclined and juxtaposed with respect to the horizontal direction ht in the apparatus main assembly 100A.

The process cartridge 70 includes an electrophotographic photosensitive drum (hereinafter referred to as "photosensitive drum") 1(1a, 1b, 1c, 1d), and process components such as a charging roller 2(2a, 2b, 2c, 2d), a developing roller 25(25a, 25b, 25c, 25d), and a cleaning member 6(6a, 6b, 6c, 6d) are integrally provided at the outer periphery of the photosensitive drum 1.

The charging roller 2 uniformly charges the surface of the photosensitive drum 1, and the developing roller 25 develops the latent image formed on the photosensitive drum 1 with toner to make the latent image visible. After the toner image formed on the photosensitive drum 1 is transferred onto a recording material (medium), the cleaning member 6 removes the toner remaining on the photosensitive drum 1.

Further, a scanner unit 3 is provided below the process cartridge 70, the scanner unit 3 being used to form a latent image on the photosensitive drum 1 by selectively exposing the photosensitive drum 1 to light based on image information.

A cartridge 17 is mounted at a lower portion of the apparatus main assembly 100A, the cartridge 17 accommodating therein a sheet of the recording material S. Further, the recording material feeding portion is provided so as to be able to be fed to the upper portion of the apparatus main assembly 100A by causing the recording material S to pass through the secondary transfer roller 69 and the fixing portion 74. That is, there are provided a feeding roller 54 for separating and feeding the sheets of the recording material S in the cassette 17 in a one-by-one manner, a feeding roller pair 76 for feeding the fed recording material S, and a registration roller pair 55 for synchronizing the latent image formed on the photosensitive drum 1 with the recording material S.

Further, an intermediate transfer unit 5 as an intermediate transfer member is provided above the process cartridges 70(70Y, 70M, 70C, 70K), and the toner image formed on each of the photosensitive drums 1(1a, 1b, 1C, 1d) is to be transferred onto the intermediate transfer unit 5. The intermediate transfer unit 5 includes a driving roller 56, a driven roller 57, primary transfer rollers 58(58a, 58b, 58c, 58d) located at positions opposed to the photosensitive drums 1 of the respective colors, and an opposed roller 59 located at a position opposed to a secondary transfer roller 69. A transfer belt (intermediate transfer belt) 9 extends and is stretched around these rollers.

Further, the transfer belt 9 is looped and moved so as to oppose and contact all the photosensitive drums 1, so that primary transfer (primary transfer of toner images) from the photosensitive drums 1 to the transfer belt 9 is carried out by applying a voltage to the primary transfer rollers 58(58a, 58b, 58c, 58 d). Then, by applying a voltage to the secondary transfer roller 69 and the opposing roller 59 disposed inside the transfer belt 9, the toner image is transferred from the transfer belt 9 onto the recording material S.

During image formation, the photosensitive drum 1 uniformly charged by the charging roller 2 is selectively exposed to light emitted by the scanner unit 3 while each of the photosensitive drums 1 is rotated. Thereby, an electrostatic latent image is formed on the photosensitive drum 1. The developing roller 25 develops the latent image. By this, toner images of the respective colors are formed on the photosensitive drums 1, respectively. In synchronization with image formation, the registration roller pair 55 feeds the recording material S to the secondary transfer position where a secondary transfer roller 69 opposed to the opposed roller 59 contacts the transfer belt 9.

Then, by applying a transfer bias to the secondary transfer roller 69, the toner images of the respective colors are secondarily transferred from the transfer belt 9 onto the recording material S. Thereby, a color image is formed on the recording material S. The fixing section 74 heats and pressurizes the recording material S on which the color image is formed, so that the toner image is fixed on the recording material S. Thereafter, the (sheet) discharge roller pair 72 discharges the recording material S onto the discharge portion 75. The fixing portion 74 is disposed at an upper portion of the apparatus main assembly 100A.

(processing box)

Next, the process cartridge 70 in this embodiment will be described with reference to fig. 3 to 5.

Fig. 3 is a principal sectional view of the process cartridge 70, and the toner is contained in the process cartridge 70. Incidentally, the process cartridge 70Y containing yellow toner, the process cartridge 70M containing magenta toner, the process cartridge 70C containing cyan toner, and the process cartridge 70K containing black toner have the same configuration.

The corresponding process cartridge 70(70Y, 70M, 70C, 70K) includes the drum unit 26(26a, 26b, 26C, 26d) as the first unit and the developing unit 4(4a, 4b, 4C, 4d) as the second unit. The drum unit 26 includes the photosensitive drum 1(1a, 1b, 1c, 1d), the charging roller 2(2a, 2b, 2c, 2d), and the cleaning member 6(6a, 6b, 6c, 6 d). Further, the developing unit 4 includes a developing roller 25.

The photosensitive drum 1 is rotatably mounted to a cleaning frame 27 of the drum unit 26 via a front drum bearing 10 and a rear drum bearing 11. The photosensitive drum 1 is provided at its end with a drum coupling 16 and a flange 19.

As described above, the charging roller 2 and the cleaning member 6 are arranged on the circumferential surface of the photosensitive drum 1. The cleaning member 6 is constituted by an elastic member formed with a rubber blade and a cleaning support member 8. The free end of the elastic member arranged in contact with the photosensitive drum 1 is oriented opposite to the rotational direction of the photosensitive drum 1. Further, the remaining toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into the removed toner chamber 27 a. Further, a receiver plate 29 for preventing leakage of the removed toner in the removal toner chamber 27a contacts the photosensitive drum 1.

The photosensitive drum 1 is rotationally driven in accordance with an image forming operation by transmitting a driving force of a main assembly driving motor (not shown) as a driving source to the drum unit 26. The charging roller 2 is rotatably mounted to the drum unit 26 via a charging roller bearing 28 and is urged against the photosensitive drum 1 by a charging roller urging member 46, thereby rotating due to the rotation of the photosensitive drum 1.

The developing unit 4 includes a developing roller 26 that rotates in contact with the photosensitive drum 1 in the arrow B direction and a developing device frame 31 for supporting the developing roller 25. Further, the developing unit 4 is constituted by a developing chamber 31b in which the developing roller 25 is disposed and a toner accommodating portion 31c, the toner accommodating portion 31c being a developer accommodating container for accommodating toner being disposed below the developing chamber 31b with respect to the gravity direction in a state in which the process cartridge is mounted in the image forming apparatus. These chambers (portions) are partitioned by partition walls 31 d. The toner accommodating portion 31 is positioned below the developing roller 25 and the developer supply roller with respect to the gravity direction. Further, the partition wall 31d is provided with an opening 31e through which the toner passes when supplied from the toner accommodating portion 31c to the developing chamber 31 b. The developing roller 25 is rotatably supported by a developing (device) frame 31 via a front developing (device) bearing 12 and a rear developing (device) bearing 13, the front developing bearing 12 and the rear developing bearing 13 being provided on both sides of the developing device frame 31, respectively (fig. 3).

Further, a developer supply roller 34 and a developing blade 35 are provided on the circumferential surface of the developing roller 25, the developer supply roller 34 being rotatable in contact with the developing roller 25 in the arrow E direction, the developing blade 35 serving to regulate the toner layer on the developing roller 25.

The developer supply roller 34 is constituted by a developer supply roller shaft 34j made of metal and a sponge portion 34a, the sponge portion 34a being an elastic portion for covering the outer peripheral surface of the shaft with the shaft end portion being in an exposed state. The developer supply roller 34 is arranged such that the sponge portion 34a contacts the developing roller 25 with a predetermined penetration amount into the developing roller 25. Further, a leakage preventing plate 33 as a developing (member) contact plate contacting the developing roller 25 is provided for preventing toner from leaking out of the developing frame 31.

Further, in the toner accommodating portion 31c in the developing frame 31, a toner supplying member 36 is provided, the toner supplying member 36 being a supplying means for supplying the toner into the developing chamber 31b through the opening 31e while agitating the toner accommodated in the toner accommodating chamber 31 c.

As described above, the toner accommodating portion 31c is disposed below with respect to the gravitational direction, and therefore the toner supplying member 36 is positioned below the developing chamber 31b with respect to the gravitational direction. That is, the developing chamber 70 in this embodiment has a toner scooping-up configuration in which toner is supplied to the developing chamber 31b by the toner supplying member 36 against gravity from the toner accommodating portion 31c arranged at a lower portion with respect to the gravity direction, and the developing chamber 31b arranged at an upper portion of the toner accommodating portion 31c with respect to the gravity direction.

Fig. 4 is an overall perspective view of the process cartridge 70. Fig. 5 is an overall perspective view of the developing unit 4. The developing unit 4 is rotatably mounted to the drum unit 26. The front supporting pin 14 and the rear supporting pin 15 are engaged with the hanging holes 12a and 13a of the rear developing bearing 12, respectively, and the front supporting pin 14 and the rear supporting pin 15 are press-fitted in the cleaning member 27. As a result, the developing unit 4 is rotatably supported by the cleaning frame 27 with the front supporting pin 14 and the rear supporting pin 15 as the rotation shafts.

Further, the cleaning frame 27 is provided with a front drum bearing 10 and a rear drum bearing 11, the front drum bearing 10 and the rear drum bearing 11 rotatably supporting the photosensitive drum 1. The rear drum bearing 11 supports a drum coupling 16 coupled to the photosensitive drum 1. Further, the front drum bearing 10 supports the flange 19. Here, the drum coupling 16 is a drum coupling member for transmitting a rotational driving force (first rotational driving force) from the apparatus main assembly 100A to the photosensitive drum 1.

The developing frame 31 is provided with a front developing bearing 12 and a rear developing bearing 13 for rotatably supporting the developing roller 25. Further, the developing unit 4 is constituted to be able to be urged against the drum unit 26 by an urging spring 32 provided at each of the end portions of the developing frame 31 during image formation of the process cartridge 70. By these urging springs 32, urging force for bringing the developing roller 25 into contact with the photosensitive drum 1 is generated with the hanging hole 12a of the front developing bearing 12 and the hanging hole 13a of the rear developing bearing 13 as rotation centers.

(inserting and mounting structure for inserting and mounting process cartridge into and into the main assembly of image forming apparatus)

In fig. 6, a configuration in which the process cartridge 70 is inserted into the image forming apparatus 100 will be described. In this embodiment, the configuration of inserting the process cartridge 70(70Y, 70M, 70C, 70K) through the opening 101(101a, 101b, 101C, 101d) of the image forming apparatus 100 is a configuration of inserting the process cartridge 70 from the front side to the rear side in a direction (arrow F direction in the drawing) parallel to the axial direction of the photosensitive drum 1(1a, 1b, 1C, 1 d).

In this embodiment, with respect to the insertion direction of the process cartridge 70, the upstream side is defined as the front side, and the downstream side is defined as the rear side. Further, in the image forming apparatus 100, a main assembly on-mounting guide portion 103(103a, 103b, 103c, 103d) as a first main assembly guide portion is provided in the upper side. Further, in the image forming apparatus 100, a main assembly lower mounting guide 102(102a, 102b, 102c, 102d) as a second main assembly mounting guide is provided in the lower side. Each of the main assembly upper guide portion 103 and the main assembly lower guide portion 102 has a guide shape extending along the insertion direction F of each of the process cartridges 70.

The process cartridge 70 is placed on the front side of the main assembly lower mounting guide 102 with respect to the mounting direction, and then moved in the insertion direction F along the main assembly upper mounting guide 102 and lower mounting guide 103, thereby being inserted into the image forming apparatus 100.

The operation of inserting the process cartridge 70 into the apparatus main assembly 100A will be described. Fig. 7(a) is a schematic diagram illustrating a state before the process cartridge 70 is mounted into the apparatus main assembly 100A.

Fig. 7(b) is a schematic diagram illustrating a state during mounting of the process cartridge 70 into the apparatus main assembly 100A. The main assembly lower mounting guide 102 provided in the apparatus main assembly 100A is provided with a main assembly (side) pressing member 104 and a main assembly (side) pressing spring 105, the main assembly pressing member 104 and the main assembly pressing spring 105 pressing and positioning the process cartridge 70 to the apparatus main assembly. When the process cartridge 70 is mounted in the apparatus main assembly 100A, the guide portion 27b of the cleaning frame 27 travels on the main assembly pressing portion 104, so that the process cartridge 70 is moved in the upward direction. Then, the guide portion 27b of the cleaning frame 27 is in a state in which the guide portion 27b is spaced from the guide surface of the main assembly lower mounting guide 102.

Fig. 7(c) is a schematic view for illustrating a state in which the process cartridge 70 is mounted into the apparatus main assembly 100A until the process cartridge 70 abuts on the rear (side) plate 98. In the state where the guide portion 27b of the cleaning frame 27 travels on the main assembly pressing member 104, when the mounting of the process cartridge 7 is further continued, the longitudinal abutment portion provided on the rear drum bearing 11 contacts the rear plate 98 of the apparatus main assembly 100A.

Fig. 7(d) and 8 are schematic views for illustrating a state in which the process cartridge 70 is positioned relative to the apparatus main assembly 100A. In the state of fig. 7, partial view (c), in relation to the front door 96 of the closing apparatus main assembly 100A, the main assembly lower mounting guide 102 including the main assembly pressing member 104 and the main assembly pressing spring 105 is moved in the upward direction. With this movement, the process cartridge 70 contacts the main assembly (side) positioning portion 98a of the rear plate 98 at the cartridge (side) positioning portion 11a, which cartridge (side) positioning portion 11a is provided at the upper portion of the rear drum bearing 11.

Then, by bringing the cartridge positioning portion 10A provided at the upper portion of the rear drum bearing 10 into contact with the main assembly positioning portion 97a as the main assembly (side) positioning portion of the front plate 97, the position of the process cartridge 70 relative to the apparatus main assembly 100A is determined. Also in this state, the guide portion 27b of the cleaning frame 27 is spaced from the guide surface of the main assembly lower mounting guide 102, so that the process cartridge 70 is in a state in which the process cartridge 70 is pressed by the spring force of the main assembly pressing spring 105 received from the main assembly pressing member 104.

Further, the cleaning frame 27 is provided on a side surface thereof with a boss 27c as a rotation stopper for the process cartridge 70, and the boss 27c is engaged with a rotation preventing hole (portion) 98b provided in the rear plate 98. Thus, the process cartridge 70 is prevented from rotating in the apparatus main assembly 100A.

(spacing mechanism between photosensitive drum and developing roller in Process Cartridge)

In the process cartridge 70 according to the present embodiment, the photosensitive drum 1 and the developing roller 25 can contact each other and be spaced apart from each other. Here, the spacing mechanism between the photosensitive drum 1 and the developing roller 25 will be described with reference to fig. 9 and 10.

In fig. 9, the apparatus main assembly is provided with a spacing member 94 at a predetermined position with respect to the longitudinal direction of the process cartridge 70. In the developing unit 4 of the process cartridge 70, the spacing force receiving portion 31a of the developing frame 31 receives a force from the spacing member 94 moving in the arrow N direction, thereby moving the developing roller 25 to a spaced position where the developing roller 25 is spaced from the photosensitive drum 1.

Further, as shown in fig. 10, when the spacing member 94 moves away from the spacing force receiving portion 31a in the arrow P direction, the developing unit 4 rotates in the arrow T direction around the hole 12a of the front developing bearing 12 and the hole 13a of the rear developing bearing 13 due to the urging force of the urging spring 32 (fig. 5) provided at the end portion of the developing frame 31. Then, the developing unit 4 is moved to the contact position so that the developing roller 25 and the photosensitive drum 1 are in contact with each other. At least during image formation, the developing unit 4 is kept in the contact position of fig. 9. Then, at a timing set in advance, such as during standby rather than during image formation, the developing unit 4 is kept in the spaced-apart position of fig. 9. Thereby, an effect of suppressing the influence of the deformation of the developing roller 25 on the image quality is obtained.

(spacer mechanism for mounting Process Cartridge)

The spacing mechanism at the time of mounting the process cartridge 70 in the apparatus main assembly 100A will be described using fig. 11 and 12.

When the process cartridge 70 is mounted in the apparatus main assembly 100A, the developing unit 4 is in the contact portion, and the photosensitive drum 1 and the developing roller 25 are in contact with each other. At the time of completion of mounting the process cartridge 70 in the apparatus main assembly 100A and at the time of end of the image forming operation of the image forming apparatus 100, the developing unit 4 is in the spaced position, and the photosensitive drum 1 and the developing roller 25 are spaced from each other.

Therefore, when the process cartridge 70 is mounted in the apparatus main assembly 100A, it is necessary to move the process cartridge 70 from the contact position to the spaced position, and the configuration thereof will be described using fig. 11 to 14. As shown in fig. 11, the apparatus main assembly 100A is provided with an image forming apparatus opening 101 for allowing the process cartridge 70 to be mounted. Further, as shown in fig. 11 and 12, the apparatus main assembly 100A is provided with a space guide portion 93, and the space guide portion 93 contacts a space force receiving portion 31a provided on the developing unit 4 of the process cartridge 70.

As shown in fig. 13 (a) and 14 (a), before the process cartridge 70 enters the apparatus main assembly 100A, the developing unit 4 is in the contact position, and the photosensitive drum 1 and the developing roller 25 are in contact with each other. Then, as shown in fig. 13 (b) and 14 (b), when the process cartridge 70 is mounted into the apparatus main assembly 100A, first, the guide portion 27b provided integrally with the cleaning frame is mounted on the main assembly lower mounting guide portion 102 provided in the apparatus main assembly 100A. Then, the spacing force receiving portion 31a provided on the developing frame 31 contacts the chamfered portion 93a, the chamfered portion 93a being an inclined surface inclined obliquely with respect to the spacing guide portion 93.

When the process cartridge 70 is caused to further enter into the apparatus main assembly, as shown in a partial view (c) in fig. 13 and a partial view (c) in fig. 14, the developing unit 4 rotates in the arrow J direction about the rear supporting pin 15 as the rotation center. Then, the developing unit 4 is moved to the spaced position in the arrow K direction. Then, when the process cartridge 70 is positioned in the apparatus main assembly 100A, as shown in partial view (d) in fig. 13 and partial view (d) in fig. 14, the spacing force receiving portion 31a is in a state of being in contact with the spacing member 94 disposed downstream of the spacing guide portion 93 with respect to the mounting direction. At this time, the developing unit 4 is in the spacing position, so that the process cartridge 70 can be mounted in the apparatus main assembly 100A while maintaining the developing roller 25 in a spaced state from the photosensitive drum 1.

(construction of developer supply roller supporting and developing (Member) Driving force input portion in Process Cartridge)

Next, a developing driving force input portion configuration and a supporting configuration of the developer supply roller 34 in the process cartridge 70 according to the present embodiment will be described using fig. 15 to 18.

Fig. 15 is a schematic view showing one longitudinal end side (rear side) of the supporting portion for the developing roller 25 and the developer supply roller 34. In fig. 5, the developing roller shaft 25j of the developing roller 25 and the developer supply roller shaft 34j of the developer supply roller 34 are rotatably engaged with the inner peripheral surface of the rear developing bearing 13. Here, the supporting configuration in one longitudinal end side of the developing roller 25 and the developer supply roller 34 is described, but also in the other longitudinal end side, similarly, a bearing portion is provided integrally with a bearing member, and the developing roller shaft 25j and the developer supply roller shaft 34j are rotatably engaged in the other end side. Further, at the developing driving force input portion, an Oldham coupling 20 as a shaft coupling member is used.

Using fig. 16, the configuration of the oldham coupling 20 will be described. Here, in order to describe the configuration of the oldham coupling 20, the rear developing bearing 13 is not shown. As shown in fig. 16, the oldham coupling 20 is composed of a driven-side engaging portion 21 as a driven portion, an intermediate engaging portion as an intermediate portion, and a driving-side engaging portion 23 as a drive receiving portion.

The driven-side engaging portion 21 is fixed and mounted to an end portion (one end portion side with respect to the axial direction) of the developer supply roller shaft 34 j. As a fixing method, there is a method of connection by a spring pin or a parallel pin and a method in which, as shown in fig. 16, the developer supply roller shaft 34j is provided at an end face thereof with a cut portion 34k and a hole in the driven-side engaging portion 21 is shaped similarly and engaged with the cut portion 34 k.

The driving-side engaging portion 23 (first drive receiving portion) is a portion for receiving a driving force of a driving source of the main assembly. Further, in this embodiment, the H direction and the I direction are in a substantially perpendicular relationship. The shaft portion 23d of the driving-side engaging portion 23 is rotatably held in the hole 41d of the holding portion 41. Further, the driving side engaging portion 23 is formed integrally with three projecting pieces 23c1, 23c2 and 23c3, and the three projecting pieces 23c1, 23c2 and 23c3 are engageable with a main assembly (side) developing (member) coupling 91 (fig. 18) as a second main assembly (side) transmitting member of the later-described 100A.

This oldham coupling 20 allows deviation between the axis of the main assembly developing coupling 91 and the axis of the developer supply roller 34, and transmits the rotational driving force (first rotational driving force) from the apparatus main assembly 100A to the developer supply roller 34. Further, the oldham coupling 20 is capable of transmitting the rotational driving force (second rotational driving force) from the apparatus main assembly 100A to the developer supply roller 34 in the case where the developing unit 4 is in the contact position and the spaced position.

In fig. 17, the construction of the oldham coupling 20 will be described in more detail using a cross-sectional view. Fig. 17(a) is a cross-sectional view of the oldham coupling 20 taken along the direction of arrow H in fig. 16, and fig. 17(b) is a cross-sectional view of the oldham coupling 20 taken along the direction of arrow I in fig. 16. In the partial view (a) of fig. 17, the driven-side engaging portion 21 is formed integrally with the rib-like member 21 a. The intermediate engaging portion 22 is provided with a groove 22a, and the rib 21a and the groove 22a are engaged with each other so that the rib 21a can move in the arrow H direction of fig. 16. In the partial view (b) of fig. 17, the driving-side engaging portion 23 is formed integrally with the rib-like member 23 b. The intermediate engaging portion 22 is provided with a groove 22b, and the rib 23b and the groove 22b are engaged with each other so as to be movable in the arrow I direction of fig. 16. In this embodiment, the H direction and the I direction are substantially perpendicular.

The intermediate engaging portion 22 is engaged with the driven-side engaging portion 21 and the driving-side engaging portion 23, and constitutes an intermediate portion for transmitting the driving force input to the driving-side engaging portion 23 to the driven-side engaging portion 21, and the intermediate engaging portion 22 is movable in a direction intersecting with the axial direction of the developer supply roller 34 while being held in engagement with each of the engaging portions 21 and 23.

Fig. 18 is a schematic diagram showing a constitution including a coupling member provided on the process cartridge 70 and a coupling member provided in the apparatus main assembly 100A. Three axially projecting protrusions 23c1, 23c2, and 23c3 are formed at the end surface of the drive-side engaging portion 23 of the oldham coupling 20 provided on the developing chamber 4. Further, a centering boss 23a for alignment with the axis (rotational center) of the main assembly developing coupling 91 projects from the end surface of the driving side engaging portion 23 in the axial direction.

The photosensitive drum 1 is provided with a triangular prism drum coupling 16 in one end side with respect to the axial direction. The guide portion 41b of the holding portion 41 is movable along the groove 43a of the side cover 43 in the direction intersecting the axial direction of the developer supply roller 34, the side cover 43 being fixed to the developing unit with screws or the like, not shown. That is, the driving-side engaging portion 23 is movable in a direction intersecting the developing unit 4 (a direction intersecting the axial direction of the developer supply roller).

In fig. 18, the main assembly drum coupling 90 is provided with a hole 90A, the cross section of the hole 90A being substantially triangular in shape, the main assembly drum coupling 90 being a first main assembly transmission member for transmitting the driving of the apparatus main assembly 100A to the photosensitive drum 1. The main assembly developing coupling 91, which is the second main assembly transmitting member for transmitting the rotational driving force (second rotational driving force) from the apparatus main assembly 100A to the developing supply roller 34, is provided with three holes 91a1, 91a2, 91a 3.

The main assembly drum coupling 90 is urged in the direction of the process cartridge 70 by a drum pressing (urging) member 106 such as a compression spring. Further, the main assembly drum coupling 90 is movable in the axial direction of the photosensitive drum 1. Further, in the case where the holes 90A of the drum coupling 16 and the main assembly drum coupling 90 are out of phase and in contact with each other when the process cartridge 70 is mounted in the apparatus main assembly 100A, the drum coupling 16 pushes the main assembly drum coupling 90, thereby retracting said main assembly drum coupling 90. Then by rotating the main assembly drum coupling 90, the drum coupling 16 and the hole 90a are engaged with each other, and the rotational driving force is transmitted to the photosensitive drum 1.

Further, a developing (member) pressing (urging) member 107 such as a compression spring urges the main assembly developing attachment 91 in the direction of the process cartridge 70 toward the direction parallel to the axial direction of the photosensitive drum 1. However, the main assembly developing coupling 91 has no gap with respect to the direction crossing the axial direction and is provided in the apparatus main assembly 100A. That is, the main assembly developing coupling 91 is not only rotated so as to transmit the drive (driving force), but also can be moved only in the axial direction.

When the driving side engaging portion 23 and the main assembly developing coupling 91 are engaged with each other by causing the process cartridge 70 to enter the apparatus main assembly 100A, the projecting members 23c1-23c3 and the holes 91a1-91a3 are out of phase in some cases. In this case, the free end portions of the projecting pieces 23c to 23c3 contact the other portions than the holes 91a1 to 91a3, so that the main assembly developing coupling 91 is retracted in the axial direction against the urging force of the developing pressing member 107. However, when the main assembly developing coupling 91 is rotated and the projecting pieces 23c1-23c3 and the holes 91a1-91a3 are in phase, the main assembly developing coupling 91a advances by the urging force of the development pressing member 107.

Then, the projecting pieces 23c1-23c3 and the holes 91a1-91a3 are engaged with each other, and the centering boss 23a and the centering hole 91b are engaged with each other so that the axes (rotational centers) of the driving side engaging portion 23 and the main assembly developing coupling 91 are coincident with each other, the centering boss 23a being an engaging portion positioning portion, and the centering hole 91b being a transmitting member positioning portion. Then, by rotating the main assembly coupling 91, the projecting pieces 23c1-23c3 and the holes 91a1-91a3 are engaged with each other, respectively, so that the rotational driving force is transmitted to the developer supply roller 34. Next, the rotation of the developing roller 25 will be described. The developer supply roller 34 is provided with a driving-side engaging portion 23 in one end side with respect to the longitudinal direction (axial direction of the developer supply roller) and a gear in the other end side. On the other hand, the developing roller 25 is provided with a gear capable of meshing with the above-described gear. With this configuration, the rotational driving force is transmitted to the developing roller 25, and the developing roller 25 is drivingly connected to the developer supply roller 34 through the gear located in the other end side with respect to the longitudinal direction.

Here, drive transmission to the main assembly drum coupling 90 and the main assembly developing coupling 91 is performed by a motor provided in the apparatus main assembly 100A. By this, the photosensitive drum 1 and the developer supply roller 34 receive the driving force from the image forming apparatus main assembly independently of each other. Incidentally, the motor may adopt a configuration using one motor for each process cartridge 70 of the corresponding color and a configuration in which the drive is transmitted to some process cartridges by a single motor.

(constitution of developing frame and rotation direction of developing roller and developer supplying roller)

Next, the configuration of the developing frame and the rotational directions of the developing roller and the developer supply roller will be described using fig. 1, 3, 19, and 26. Fig. 1 is a schematic diagram showing a driving force input portion and a driving system of the developing unit in the present embodiment. Fig. 3 is a schematic view showing a cartridge mounted in the image forming apparatus. Fig. 19 is a schematic diagram showing the configuration of the developing chamber in the present embodiment. Fig. 26 is a schematic diagram illustrating a comparative example in which a developing chamber toner supply member is provided in a developing chamber.

As described above, the toner accommodating portion 31c of the developing frame 31 is provided with the toner supply member 36 (fig. 3) for not only stirring the accommodated toner but also supplying the toner to the developing chamber 31b via the toner opening 31 e. Incidentally, in this embodiment, a configuration is adopted in which the developing roller 25 and the developer supply roller 34 are provided in the developing chamber 31 b. Further, the toner accommodating portion 31c is provided below the developing chamber 31b with respect to the gravitational direction, and thus the toner supplying member 36 is positioned below the developing chamber 31b with respect to the gravitational direction. That is, the process cartridge 70 in the present embodiment has an upward scooping configuration in which toner is supplied from the toner accommodating portion 31c to the developing chamber 31b by the toner supplying member 36 against gravity, the toner accommodating portion 31c being arranged below the developing chamber 31b with respect to the direction of gravity, and the developing chamber 31b being arranged above the toner accommodating portion 31c with respect to the direction of gravity.

The developer supplied from the toner accommodating portion 31c to the developing chamber 31b stagnates at a developing chamber bottom (portion) 31f, as shown in fig. 19. In order to supply the developer stagnating at the developing chamber bottom 31f to the developer supply roller, as a comparative example, as shown in fig. 26, a developing chamber toner supply member 37 is provided at the developing chamber bottom 31f, and the developing chamber toner supply member 37 is moved so that the developer stagnating at the developing chamber 31f is supplied to the developer supply roller 34.

In this embodiment, as shown in fig. 19, the developer supply roller 34 is provided so as to be rotatable in a direction (arrow E direction) opposite to the rotational direction (arrow B direction) of the developer supply roller 34. That is, at the contact portion between the developing roller 25 and the developer supply roller 34, the respective surfaces thereof are along the moving direction in the same direction. Incidentally, as shown in fig. 1, the rotational direction of the photosensitive drum 1 is opposite to the rotational direction of the developing roller. Further, the rotational direction of the photosensitive drum 1 is the same as the rotational direction of the developer supply roller 34.

In fig. 19, the developer supply roller 34 has a configuration provided with a sponge portion (elastic layer having inner porous portions) 34 a. Further, in fig. 19, the developing roller 25 has an elastic layer 25 a. The surface hardness of the developer supply roller 34 is lower than that of the developing roller 25, and therefore when the two rollers contact each other, as shown in fig. 19, the developer supply roller is dented (deformed). Here, as shown in fig. 19, the developer supply roller 34 is in a state where the surface of the sponge portion 34a is deformed corresponding to the amount of intrusion of the contact portion with the developing roller 25. At this time, the toner contained in the sponge portion 34a is discharged from the sponge portion 34 a. Hereinafter, a portion where the toner is discharged by the deformation of the sponge portion 34a is referred to as a discharge portion 34b and will be described. Such a discharge portion 34b is a region located in the upstream side of the contact portion between the developer supply roller 34 and the developing roller 25 with respect to the rotational direction of the developer supply roller 34.

On the other hand, at a portion where the developer supply roller 34 rotationally advances and in a state where the developer supply roller 34 is restored from the deformed state, the air pressure inside the sponge portion 34a decreases with the restoration. For this reason, an air flow for carrying the toner toward the inside of the sponge portion 34a is generated. Hereinafter, a portion at which the state of the sponge portion 34a is restored from the deformed state and the toner is brought in is referred to as an entering portion 34c and the entering portion 34c will be described. Such an entering portion 34c is a region located in the downstream side of the contact portion between the developer supply roller 34 and the developing roller 25 with respect to the rotational direction of the developer supply roller 34. The toner entered into this area is discharged again at the discharge portion 34 b.

In this way, during the rotational driving of the developer supply roller 34, the toner is circulated by continuously performing the above-described intake and discharge, and in the process, the supply of the developer to the developing roller 25 is performed. In order to stably supply the developer to the developing roller 25, it is important to stably supply the toner to the inlet portion 34 c.

As shown in fig. 26, the rotational direction (arrow C direction) of the developer supply roller 34 in the comparative example is set to be the same as the rotational direction (arrow B direction) of the developing roller 25 in many cases. In this case, as in this embodiment, in the configuration in which the toner is supplied from the lower toner accommodating portion 31c to the upper developing chamber 31b, the entering portion 34c is positioned above the developing roller 25 and the developer supplying roller 34. Therefore, in order to stably supply the toner to the entering portion 34c, it is necessary to provide such an arrangement relationship that the developer supply roller 34 itself does not block the toner that passes through the toner opening 31e and moves toward the entering portion 34c positioned above the developer supply roller 34. Further, at the bottom portion 31f of the developing chamber 31c, a state is formed in which the toner discharged from the discharging portion 34b, the toner falling down due to the regulation of the developing blade 35, and the toner supplied from the toner accommodating portion 31c are collected. To stir and circulate these toners, at the bottom 31f of the developing chamber 31b, a developing chamber toner supplying member 37 as a stirring member is provided and it is necessary to supply the toners to the developer supplying roller 34 through the developing chamber toner supplying member 37.

On the other hand, in this embodiment, the entering portion 34c is positioned below the developing roller 25 and the developer supply roller 34 and near the bottom portion 31f of the developing chamber 31b with respect to the direction of gravity as shown in fig. 19. That is, the airflow generated at the entrance portion 31c causes the toner supplied to the developing chamber 31b to move to the rear, so that the entrance portion is located at a position where the toner easily naturally reaches the entrance portion 31 c. Therefore, the restriction of the arrangement relationship between the toner opening 31e and the developer supply roller 34 as in the conventional configuration is alleviated, and therefore the degree of design flexibility of the arrangement of the toner opening 31e and the developer supply roller 34 becomes high.

Here, when the lower end 31e2 of the toner opening 31e is arranged at a position higher than the bottom 31f of the developing chamber 31 with respect to the gravity direction, the toner surface is raised to a position close to the entering portion 34c, and therefore such an arrangement scheme is more desirable. In particular, when the position of the lower end 31e2 of the toner opening 31e is set at a position higher than the entering portion 34c with respect to the gravity direction, the toner surface in the developing chamber 31b always reaches the height of the entering portion 34c, and thus the toner supply performance to the developing chamber 31c is further stabilized. In this embodiment, the height of the lower end 31e2 of the toner opening 31e is arranged at a position higher than the downstream end of the contact portion between the developer supply roller 34 and the developing roller 25 with respect to the rotational direction of the developer supply roller 34. Further, the entering portion 34c is positioned close to the bottom portion 31f of the developing chamber 31b, and thus the toner accumulated at the bottom portion 31 naturally enters into the developer supplying roller 34 and is gradually consumed.

Therefore, as in the conventional configuration, even when the developing chamber toner supplying member 37 as shown in fig. 26 is not used, the toner can be circulated, and therefore the space where the developing chamber toner supplying member 37 is arranged in the conventional manner can be filled, so that the remaining toner can be reduced.

(surface speed and roller diameter of developing roller and developer supply roller)

Using fig. 19, the surface speeds of the developing roller 25 and the developer supply roller 34 will be described. As shown in fig. 19, the developing roller 25 and the developer supply roller 34 rotate in opposite directions. Incidentally, at the contact portions, the respective surfaces move in the same direction. Here, the surface speed of the developer supply roller 34 is set higher than the surface speed of the developing roller 25. This is because the toner supply performance of supplying toner to the developing roller 25 and the performance of peeling off the toner on the developing roller 25 that is not used for development are taken into consideration. The surface speed of the developer supply roller 34 is higher than that of the developing roller 25, so that the portion of the sponge portion 34a containing a sufficient amount of toner always contacts the developing roller 25, and thus the toner can be stably supplied to the developing roller 25. Further, with respect to the toner peeling property, the surface speed of the developer supply roller 34 is higher than the surface speed of the developing roller 25 and thus a frictional force due to the circumferential speed driving force is generated, so that the toner on the developing roller 25 which is not used for development can be peeled off.

Incidentally, regarding the toner supplying performance and the toner exfoliating performance, it is known that the effect is more remarkable when the circumferential speed difference is larger. However, the number of revolutions of the developing roller 25 has a large influence on the toner supply performance to supply toner to the photosensitive drum 1, and therefore, it is not desirable from the viewpoint of the developing process to provide a peripheral speed difference by reducing the number of revolutions of the developing roller 25.

Therefore, in order to increase the peripheral speed while maintaining the rotation number of the developing roller 25, a method of relatively increasing the rotation number of the developer supplying roller 34 by changing a gear ratio (fig. 1) between the developer supplying roller gear 38 and the developing roller gear 39 described later and a method in which the diameter 34r of the sponge portion 34a is increased are used. In the case where the number of rotations of the developer supply roller 34 is relatively increased while maintaining the number of rotations of the developing roller 25, it is necessary to increase the output from a main assembly driving motor (not shown) as a driving source, and therefore a large amount of electric power is required. Therefore, also in order to suppress power consumption, the diameter 34r of the sponge portion 34a may desirably be large, and in this embodiment, the diameter 25r of the developing roller 25 is set to 12mm and the diameter 34r of the developer supplying roller 34 is set to 13.3mm so that the diameter ratio therebetween is about 1.11. However, the diameter 34r of the sponge portion 34a is not necessarily required to be larger than the diameter 25r of the developing roller 25, but a desired circumferential speed difference may also be given by a gear ratio. Incidentally, although the driving system in the present embodiment will be described later, with respect to the number of teeth of the developer supply roller gear 38 and the developing roller gear 39 (fig. 1) directly connected to each other, the number of teeth of the developer supply roller gear 38 is set to 18 teeth, and the number of teeth of the developing roller gear 39 is set to 26 teeth, so that the gear ratio therebetween is about 1.44.

Here, it is desirable that the circumferential speed ratio is set to be between 1.3 or more and 1.8 or less with respect to the surface speed ratio between the developing roller 25 and the developer supply roller 34 (i.e., (developer supply roller surface speed)/(developing roller surface speed), hereinafter referred to as "circumferential speed ratio"). Such a setting range is a range that enables maintenance of necessary and sufficient toner supply performance and toner peeling performance. When the peripheral speed ratio is less than 1.3, good toner peeling properties may not be maintained, so that ghost or the like may be caused to the image quality. Further, when the peripheral speed ratio is 1.8 or less, the toner supplying performance and the toner peeling performance can be sufficiently maintained. For this reason, when the peripheral speed ratio exceeds 1.8, friction becomes large and therefore abrasion of the developer supply roller and the developing roller is liable to be generated, and therefore it is undesirable that the surface speed of the developer supply roller 34 excessively increases. Here, in this embodiment, with the above-described diameter ratio and gear ratio, the surface speed of the developing roller 25 is set to about 304mm/s and the surface speed of the developer supply roller 34 is set to about 487mm/s, so that the peripheral speed ratio therebetween is about 1.60. In this arrangement, it has been confirmed that sufficient effects can be obtained with respect to the toner supplying performance and the toner exfoliating performance. Incidentally, the surface speed referred to herein is the speed of a portion on the surface other than the contact portion between the developing roller 25 and the developer supply roller 34, and this is similarly applicable to the peripheral speed ratio.

(drive input and drive System for developing Unit)

Using fig. 1 and 20, a drive input configuration and a configuration of a drive system for the developing unit 4 will be described. As described above, the driving force output from the main assembly driving motor (not shown) as the driving source of the apparatus main assembly 100A is input into the developing unit 4 by the engagement of the main assembly developing coupling 91 of the apparatus main assembly 100A with the driving side engaging portion 23 of the oldham coupling 20 provided at the end portion of the shaft portion 34j of the developer supplying roller 34.

Here, first, a drive input configuration of the developing unit 4 will be described using fig. 1. Fig. 1 is a schematic diagram showing a driving system for the developing unit 4, and for the sake of simplifying the explanation, only the developing roller 25, the developer supplying roller 34, and the driving system with respect to these rollers are extracted and shown.

As shown in fig. 1, the shaft portion 34j of the developer supply roller 34 is provided with a developer supply roller gear 38, and the developer supply roller gear 38 is an upstream transmitting member (first transmitting portion). Similarly, the shaft portion 34j of the developing roller 25 is provided with a developing roller gear 39 as a downstream transmitting member (second transmitting portion), the developing roller gear 39 being provided so as to be capable of directly meshing with the developer supplying roller gear 38. Incidentally, in this embodiment, the gear train such as the developer supply roller gear 38 is disposed on the side (on the other side) opposite to the driving force input portion of the developing unit 4 with respect to the axial direction from the viewpoint of space or the like, but the gear train and the driving force input portion may also be disposed on the same side. Here, the rotational directions of the developing roller 25 and the developer supply roller 34 are opposite to each other, and therefore it is not necessary to provide an idler gear between the developer supply roller gear 38 and the developing roller gear 39, and therefore the number of components can be reduced. The driving force input to the shaft of the developer supply roller 34 is transmitted from the developer supply roller gear 38 to the developing roller 25 via the developing roller gear 39. Incidentally, as described above, in this embodiment, the number of teeth of the developer supply roller gear 38 is set to 18 teeth, and the number of teeth of the developing roller gear 39 is set to 26 teeth.

Using fig. 20, a driving system for the developing unit will be described. Fig. 20 is a schematic diagram showing a driving system in the downstream side of the developing roller 25.

As shown in fig. 20, in the downstream side of the developing roller gear 39, a developing (member) idler gear 80, an agitation idler gear 81, and an agitation gear 82 for transmitting drive to the toner supplying member 36 are provided in the listed order. The developing idle gear 80 and the stirring idle gear 81 are rotatably supported by the front developing bearing 12, and the stirring gear 81 is rotatably supported by the developing frame 31 in a state where the stirring gear 82 is connected to the toner supplying member 36 by a not-shown connecting part (such as a snap-fit part and an engaging part). The driving force input to the shaft of the developer supply roller 34 is transmitted in the order of the developer supply roller gear 38, the developing roller gear 39, the developing idler gear 80, the stirring idler gear 81, and the stirring gear 82 and finally transmitted to the toner feeding member 36.

(Small deformation of developer supply roller)

Using fig. 21 and 22, a small deformation generated at the sponge portion 34a of the developer supply roller 34 will be described. The developer supply roller 34 is always supported in a contact state with the developing roller 25, but when the developer supply roller 34 is on standby for a long period of time under a high-temperature environment or the like, then a small plastic deformation as shown in fig. 21 is generated at the contact portion with the developing roller 25 in some cases. Hereinafter, with respect to the developer supply roller 34, the region where small plastic deformation occurs will be referred to as a small deformation portion 34n and will be described.

First, fig. 22 is a schematic diagram showing a configuration in which, unlike the present embodiment, the driving force from the main assembly is not input into the developer supply roller 34, but is input into the developing roller 25. In this configuration, the developing roller gear 39 drives the developer supply roller gear 38. Here, fig. 23 is a schematic view showing one tooth of each of the developer supply roller gear and the developing roller gear at the joint between the teeth 38a and 39a of the developer supply roller gear. Fig. 23(a) is a schematic diagram showing a state where the sponge portion 34a without deformation reaches a contact position with the developing roller 25, and fig. 23(b) is a schematic diagram showing a state where the small deformation portion 34n reaches a contact position with the developing roller 25. A broken line 39b shown in a partial diagram (b) in fig. 23 represents the behavior of the developing roller gear teeth 39a in a state where the load from the developer supply roller gear 38 is reduced. Using fig. 22 and 23, the influence due to small deformation of the developer supply roller 34 will be described.

In the case where the sponge portion 34a of the developer supply roller 34 is not deformed, as shown in the partial view (a) in fig. 23, the developing roller gear teeth 39a rotate in a state where the developing roller gear teeth 39a receive a certain load from the developer supply roller gear teeth 38 a. However, when the small deformation portion 34n of the developer supply roller 34 reaches the contact position with the developing roller 25, the frictional force generated between the developing roller 25 and the developer supply roller 34 is instantaneously reduced. By this, the developer supply roller 34 is in a state in which the developer supply roller 34 is apt to rotate instantaneously, and therefore, as shown in a partial diagram (b) in fig. 23, the load received by the driven developing roller gear teeth 39a from the developer supply roller gear teeth 38a is instantaneously reduced. Thereby, the rotational speed of the developing roller 25 is instantaneously increased. Therefore, the surface speed of the driving side 25 is instantaneously increased relative to the surface speed of the photosensitive drum 1, and therefore it is possible to generate non-uniformity in toner supply performance from the developing roller 25 to the photosensitive drum 1 and thus generate a phenomenon such as lateral streaks on an image. Incidentally, it is known that such a phenomenon is liable to occur as the peripheral speed difference between the surface speed of the developing roller 25 and the surface speed of the developer supply roller 34 gradually increases.

On the other hand, in the embodiment shown in fig. 1, the developer supply roller 34 is in a state in which the developer supply roller 34 is instantly easily rotated by making the small deformation portion 34n of the developer supply roller 34 pass through the contact portion with the developing roller 25. However, as shown in fig. 24, the load for rotating the developing roller 25 does not fluctuate greatly, and therefore does not affect the behavior of the developing roller 25. Therefore, even if a small deformation is generated at the sponge portion 34a of the developer supply roller 34, non-uniformity in the developer supply performance from the developing roller 25 to the photosensitive drum 1 is not easily generated. Therefore, the configuration of inputting the driving force to the developer supply roller 34 can suppress the image quality from being degraded, as compared with the configuration of inputting the driving force into the developing roller 25.

Here, when the toner peeling performance, the power consumption, and the influence of the small deformation of the sponge portion 34a on the image are summarized from the perspective of the above-described roller peripheral speed difference, the tendency as shown in the table of fig. 25 is obtained from the experimental result. That is, also from the viewpoint of the influence of small deformation of the sponge portion 34a on the image, the circumferential speed difference between the surface speed of the developing roller 25 and the surface speed of the developer supply roller 34 may be desirably set to be (developer supply roller/developing roller) ═ 1.3 or more and 1.8 or less.

As described above, according to the present embodiment, in the developing device of the configuration in which the toner is drawn up from the toner accommodating chamber disposed below the developing chamber 31B to the upper developing chamber 31B, the rotational direction (arrow C direction) of the developer supply roller 34 is opposite to the rotational direction (arrow B direction) of the developing roller. Thereby, toner stagnation can be suppressed while it is not necessary to provide an agitating member in the developing chamber 31b, and thus the number of parts and the amount of remaining toner can be reduced. Further, the surface speed of the developer supply roller 34 is set higher than that of the developing roller, whereby the developer can be stably supplied to the developing roller. Further, a driving force is input from the image forming apparatus main assembly to the shaft of the developer supply roller 34, whereby it is possible to reduce image defects generated when, for example, the developer supply roller 34 is on standby for a long period of time in a high-temperature environment or the like. In summary, in the developing device having the scooping configuration including the toner accommodating chamber 31c located below the developing chamber, it is possible to provide the process cartridge and the image forming apparatus capable of improving image quality while reducing the number of components and reducing the amount of remaining toner.

[ INDUSTRIAL APPLICABILITY ]

According to the present invention, there are provided a process cartridge and an image forming apparatus capable of reducing residual toner while reducing the number of parts in a configuration in which toner is drawn up from a developer accommodating chamber provided below the developer accommodating chamber to a developing chamber above the developer accommodating chamber.

Claims

1. A process cartridge comprising:

(i) a photosensitive drum;

(ii) a rotatable developing roller configured to develop an electrostatic latent image formed on the photosensitive drum;

(iii) a rotatable toner supply roller provided in contact with the developing roller, the rotatable toner supply roller configured to supply toner to the developing roller;

(iv) a toner chamber configured to contain toner;

(v) a developing chamber in which the rotatable toner supply roller is positioned;

(vi) a rotatable feeding member provided in the toner chamber and configured to feed toner from the toner chamber into the developing chamber;

(vii) a coupling operatively connected to the toner supply roller and configured to receive a driving force for rotating the toner supply roller, the developing roller, and the feeding member;

(viii) a first driving force transmitting portion operatively connected to the toner supply roller and configured to transmit the driving force received by the coupling to the developing roller; and

(ix) a second driving force transmitting portion operatively connected to the developing roller and configured to transmit the driving force from the first driving force transmitting portion to the developing roller,

wherein the process cartridge is configured such that, when the coupling receives the driving force and the process cartridge is oriented with the developing roller positioned above the toner chamber, (i) a rotational direction of the developing roller is opposite to a rotational direction of the toner supply roller, (ii) a portion of a surface of the toner supply roller rotates from a first position where the portion of the surface of the toner supply roller contacts the surface of the developing roller to a second position where the portion of the surface of the toner supply roller moves out of contact with the surface of the developing roller, the first position is above the second position, (iii) the supplying member supplies the toner upward from the toner chamber to the developing chamber, and (iv) the speed of the surface of the toner supply roller is greater than the speed of the surface of the developing roller.

2. A process cartridge according to claim 1, wherein at least a part of said coupling is rotatable relative to said toner supply roller in a direction crossing a rotational axis of said toner supply roller.

3. A process cartridge according to claim 1, wherein said coupling member is an oldham coupling.

4. A process cartridge according to claim 1, wherein said toner supply roller and a wall of said developing chamber define a space for storing toner therebetween.

5. A process cartridge according to claim 1, wherein a diameter of said toner supply roller is larger than a diameter of said developing roller.

6. A process cartridge according to claim 1, wherein a ratio of the speed of the surface of said toner supply roller to the speed of the surface of said developing roller is:

1.3. ltoreq. toner supply roller/developing roller. ltoreq.1.8.

7. A process cartridge according to claim 1, wherein said toner supplying roller includes an elastic layer.

8. A process cartridge according to claim 1, wherein said toner supplying roller includes a sponge configured to store toner.

9. A process cartridge according to claim 1, wherein said driving force is transmitted from said second driving force transmitting portion to said feeding member.

10. A process cartridge according to claim 9, wherein said second driving force transmitting portion is configured to transmit said driving force to said feeding member via at least one gear.

11. A process cartridge according to claim 10, further comprising:

a first idle gear engaged with the second driving force transmission portion;

a second idler gear engaged with the first idler gear; and

a feed member gear operatively connected to the feed member and engaged with the second idler gear,

wherein the driving force is transmitted from the second driving force transmitting portion to the feeding member via the first idle gear, the second idle gear, and the feeding member gear.

12. A process cartridge according to claim 1, wherein said coupling is provided at an end of a shaft of said toner supply roller.

13. A process cartridge according to claim 1, wherein said first driving force transmitting portion and said coupling are disposed on opposite sides of said toner supply roller with respect to an axial direction of said toner supply roller.

14. A process cartridge according to claim 1, wherein a rotation direction of said toner supply roller is the same as a rotation direction of said feeding member.

15. A process cartridge according to claim 1, wherein said developing roller is movable toward and away from said photosensitive drum.

16. A process cartridge according to claim 15, further comprising:

a first unit including a photosensitive drum; and

a second unit including a developing roller, a toner supplying roller, and a supplying member,

wherein the developing roller is movable toward and away from the photosensitive drum by movement of the second unit relative to the first unit.

17. A process cartridge according to claim 1, wherein said photosensitive drum includes a coupling member configured to receive a driving force for rotating the photosensitive drum.

18. A process cartridge according to claim 1, wherein the second driving force transmitting portion is engaged with the first driving force transmitting portion to transmit the driving force from the first driving force transmitting portion to the developing roller.

19. A process cartridge according to claim 1, wherein said coupling member includes a plurality of projections extending from a side of the coupling member opposite to the toner supply roller.

20. A process cartridge comprising:

(i) a photosensitive drum;

(iv) a toner chamber configured to contain toner;

(vi) a supply member provided in the toner chamber and configured to supply toner from the toner chamber into the developing chamber;

(vii) a coupling operatively connected to the toner supply roller and configured to receive a driving force for driving the toner supply roller, the developing roller, and the feeding member;

wherein the developing roller is configured to receive a driving force from a coupling via the toner supply roller, and

21. A process cartridge according to claim 20, wherein said toner supply roller and a wall of said developing chamber define a space for storing toner therebetween.

22. A process cartridge according to claim 20, wherein said toner supplying roller has a diameter larger than a diameter of said developing roller.

23. A process cartridge according to claim 20, wherein a ratio of the speed of the surface of said toner supply roller to the speed of the surface of said developing roller is:

1.3. ltoreq. toner supply roller/developing roller. ltoreq.1.8.

24. A process cartridge according to claim 20, wherein said toner supplying roller includes an elastic layer.

25. A process cartridge according to claim 20, wherein said toner supplying roller includes a sponge configured to store toner.

26. A process cartridge according to claim 20, wherein said coupling is provided at an end of a shaft of said toner supply roller.

27. A process cartridge according to claim 20, wherein said photosensitive drum includes a coupling member configured to receive a driving force for rotating the photosensitive drum.

28. A process cartridge according to claim 20, wherein said coupling member includes a plurality of projections extending from a side of the coupling member opposite to the toner supply roller.