Patent Grant
11415912
This application claims priority from Japanese Patent Application No. 2020-023415 filed Feb. 14, 2020. The entire content of the priority application is incorporated herein by reference.
The present disclosure relates to a developing cartridge including an agitator configured to agitate toner accommodated in a casing.
There has been known a developing cartridge including: a casing for storing toner therein; and a developing roller rotatably positioned in the casing; a supply roller for supplying the toner to the developing roller. This developing cartridge includes: a first agitator including a blade for agitating the toner and rotatably supported by the casing; and a second agitator including a blade for toner agitation and rotatably supported by the casing at a position between the first agitator and the supply roller.
However, providing the first and second agitators in the casing may not necessarily lead to sufficient agitation of the toner. Insufficient toner agitation may cause aggregation of toner on the supply roller, for example, and such aggregated toner may move from the supply roller to the developing roller. In this case, if a layer-thickness regulating blade scrapes the aggregated toner from the developing roller, an amount of the toner left on the developing roller becomes excessively reduced, which may result in printing blur. Particularly, in a developing cartridge where the developing roller is positioned below the supply roller in an attached posture of the developing cartridge to an image-forming apparatus, the aggregation of toner is likely to occur on the supply roller due to gravity effect, and the above described tendency becomes outstanding.
In view of the foregoing, it is an object of the disclosure to provide a developing cartridge capable of restraining toner from being aggregated on the supply roller and restraining the aggregated toner from moving to the developing roller.
In order to attain the above and other objects, according to one aspect, the disclosure provides a developing cartridge including a casing, a developing roller, a supply roller, a first agitator, and a second agitator. The casing is configured to accommodate toner therein. The supply roller is configured to supply the toner to the developing roller. The first agitator is configured to agitate the toner in the casing. The second agitator is configured to agitate the toner in the casing. The second agitator is positioned between the first agitator and the supply roller. The second agitator includes a blade having a tip end configured to contact a peripheral surface of the supply roller.
The particular features and advantages of the embodiment(s) as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which:
Hereinafter, one embodiment of the present disclosure will be described with reference to the accompanying drawings. In the following description, an overall structure of an image-forming apparatus 1 will be described first, and, thereafter, features of the present disclosure will be described.
The image-forming apparatus 1 according to the embodiment is a color printer. As illustrated in
Hereinafter, throughout the specification, a right side, a left side, an upper side, and a lower side in
The housing 10 has a front end formed with a first opening 10A. The cover 11 is pivotally movable relative to the housing 10 between a closed position closing the first opening 10A (as indicated by a solid line) and an open position opening the first opening 10A (as indicated by a two-dotted chain line). The housing 10 has an upper surface region serving as a discharge tray 13.
The sheet supply unit 20 is positioned at a lower internal portion of the housing 10. The sheet supply unit 20 includes the sheet tray 21 for accommodating sheets S, and a sheet supply mechanism 22 configured to supply one sheet S from the sheet tray 21 toward the image-forming unit 3. The sheet tray 21 is detachable from the housing 10 by being pulled out forward (toward the right in
In the sheet supply unit 20, the sheet(s) S accommodated in the sheet tray 21 is fed by the sheet supply roller 23, and then the sheet(s) S is separated one by one by the separation roller 24 and the separation pad 25. Thereafter, a position of a leading edge of each sheet S is regulated by the registration rollers 27 during a halt of the rotations of the registration rollers 27, and then, the sheet S is supplied to the image-forming unit 3 by the rotations of the registration rollers 27.
The image-forming unit 3 includes an exposure device 4, a plurality of (four) photosensitive drums 50, a plurality of (four) developing cartridges 60, a plurality of (four) chargers 52, a conveying unit 70, and a fixing device 80. Each of the developing cartridge 60 includes a developing roller 61.
The exposure device 4 includes a laser diode, a deflector, lenses, and mirrors those not illustrated. The exposure device 40 is configured to expose peripheral surfaces of the respective photosensitive drums 50 to a plurality of laser beams for scanning the peripheral surfaces of the respective photosensitive drums 50.
The plurality of developing cartridges 60 is provided in one-to-one correspondence with the plurality of photosensitive drums 50. The plurality of chargers 52 is also provided in one-to-one correspondence with the plurality of photosensitive drums 50.
The conveying unit 70 is positioned between the sheet tray 21 and the plurality of photosensitive drums 50. The conveying unit 70 includes a drive roller 71, a driven roller 72, a conveyer belt 73, and four transfer rollers 74. The conveyer belt 73 is an endless belt mounted over the drive roller 71 and the driven roller 72 under tension. The conveyer belt 73 has an outer surface (upper outer surface) facing the respective photosensitive drums 50. Each transfer roller 74 is positioned inside a loop of the conveyer belt 73, and is configured to nip the conveyer belt 73 in cooperation with a corresponding one of the photosensitive drums 50. In the conveyer unit 70, the sheet S mounted on the upper outer surface of the conveyer belt 73 is conveyed by the movement of the conveyer belt 73. At this time, toner images formed on the plurality of the photosensitive drums 50 are transferred onto the sheet S.
The fixing device 80 is positioned rearward of the plurality of photosensitive drums 50 and the conveying unit 70. The fixing device 80 includes a heat roller 81, and a pressure roller 82 facing the heat roller 81. Further, a pair of conveying rollers 15 is positioned above the fixing device 80, and a pair of discharge rollers 16 is positioned above the conveying rollers 15.
In the image-forming unit 3 configured as above, after the chargers 52 uniformly charge the peripheral surfaces of the respective photosensitive drums 50, the peripheral surface of each photosensitive drum 50 is exposed to laser light by the exposure device 40, thereby an electrostatic latent image corresponding to image data is formed on the peripheral surface of each photosensitive drum 50.
In the meantime, toner accommodated in each developing cartridge 60 is carried on a peripheral surface of the corresponding developing roller 61, and the toner is supplied to the electrostatic latent image formed on the corresponding photosensitive drum 50 when the developing roller 61 contacts the photosensitive drum 50. Thus, a toner image is formed on each of the photosensitive drums 50.
Subsequently, the toner images on the respective photosensitive drums 50 are transferred to the sheet S while the sheet S on the conveyer belt 73 passes between each photosensitive drum 50 and the corresponding transfer roller 74. As the sheet S then passes between the heat roller 81 and the pressure roller 82, the toner images are thermally fixed to the sheet S.
The sheet S is then discharged onto the discharging tray 13 by the conveying rollers 15 and the discharge rollers 16.
Next, a structure of each developing cartridge 60 will be described in detail.
In the following description, an extending direction of a developing axis 61X (described later) of the developing roller 61 will be referred to as a “first direction”. Further, a direction crossing the first direction and connecting the developing axis 61X to a first agitator axis 31X of a first agitator 30 (described later) will be referred to as a “second direction”. Specifically, in the present disclosure, the second direction is perpendicular to the first direction.
As illustrated in
As illustrated in
The developing roller 61 is positioned at one end portion of the casing 62 in the second direction. The developing roller 61 includes: a developing roller shaft 61A extending in the first direction; and a roller portion 61B disposed over a peripheral surface of the developing roller shaft 61A. The developing roller 61 is rotatable about the developing axis 61X extending in the first direction. The developing roller shaft 61A is made from metal. The roller portion 61B is made from electrically conductive rubber.
The supply roller 63 is rotatably supported by the casing 62 and is configured to supply toner to the developing roller 61. The supply roller 63 includes: a supply roller shaft 63A extending in the first direction; and a roller portion 63B disposed over a peripheral surface of the supply roller shaft 63A. The supply roller 63 is rotatable about a supply axis 63X extending in the first direction. The supply roller shaft 63A is made from metal. The roller portion 63B is made from sponge.
The first agitator 30 is rotatably supported by an approximately center portion of the casing 62, and is configured to agitate the toner in the casing 62. The first agitator 30 includes: a shaft 31 extending in the first direction; and a blade 32. The first agitator 30 is rotatable about a first agitator axis 31X extending in the first direction.
A support shaft portion 31A is provided at another end portion of the shaft 31 in the first direction to protrude therefrom. The casing 62 has an inner surface 62D. The support shaft portion 31A is supported by a recessed portion formed on the inner surface 62D of the casing 62. The shaft 31 of the first agitator 30 is made from resin.
The blade 32 of the first agitator 30 extends from the shaft 31 toward the inner surface 62D of the casing 62. The blade 32 has a tip end 32A configured to make sliding contact with the inner surface 62D. That is, the tip end 32A of the blade 32 of the first agitator 30 defines a rotation locus L3 which partially overlaps with the inner surface 62D of the casing 62. The blade 32 of the first agitator 30 is a flexible plate-like sheet, and is configured to flex upon contacting the inner surface 62D of the casing 62. The blade 32 is made from resin such as PET (polyethylene terephthalate).
The second agitator 40 is positioned between the first agitator 30 and the supply roller 63 in the second direction, and is configured to agitate the toner in the casing 62. The second agitator 40 includes: a shaft 41 extending in the first direction; and a blade 42. The second agitator 40 is rotatable about a second agitator axis 41X extending in the first direction.
The shaft 41 has a generally triangular cross-section. The blade 42 is affixed (adhesively bonded) to one surface of the triangle of the shaft 41. The blade 42 extends from the shaft 41 toward the inner surface 62D of the casing 62. The blade 42 is a film-like sheet having a flexibility, and is made from resin such as polyethylene terephthalate. The flexibility of the blade 42 is higher than a flexibility of the blade 32.
The shaft 41 is positioned outside of the rotation locus L3 of the first agitator 30. Specifically, the shaft 41 is positioned outside of the rotation locus L3 of the tip end 32A of the blade 32 of the first agitator 30. In other words, a distance D1 between the first agitator axis 31X and the shaft 41 is greater than a radius R1 of the rotation locus L3 of the first agitator 30.
The rotation locus L3 of the first agitator 30 is overlapped with a rotation locus L4 of the second agitator 40. That is, the blade 32 of the first agitator 30 is contactable with the blade 42 of the second agitator 40.
The blade 42 has a tip end 42A contactable with a peripheral surface of the supply roller 63. However, the tip end 42A of the blade 42 is out of contact with the inner surface 62D of the casing 62. That is, the tip end 42A of the blade 42 defines the rotation locus L4 that is positioned away from the inner surface 62D. In other words, a minimum distance D2 between the second agitator axis 41X and the inner surface 62D of the casing 62 is greater than a radius R2 of the rotation locus L4 of the second agitator 40. Hence, the tip end 42A of the blade 42 of the second agitator 40 contacts the peripheral surface of the supply roller 63 whereas the tip end 42A does not contact the inner surface 62D of the casing 62 in accordance with the rotation of the second agitator 40.
As illustrated in
The developing gear 120 is attached to the developing roller shaft 61A. The supply gear 130 is attached to the supply roller shaft 63A. The first agitator gear 150 is attached to the shaft 31 of the first agitator 30. The second agitator gear 180 is attached to the shaft 41 of the second agitator 40.
The coupling 110 includes a large diameter gear 111 and a small diameter gear 112. The large diameter gear 111 is in meshing engagement with the developing gear 120. The small diameter gear 112 is in meshing engagement with the supply gear 130 and the first idle gear 140.
The first idle gear 140 includes a large diameter gear 141 and a small diameter gear 142. The large diameter gear 141 is in meshing engagement with the small diameter gear 112 of the coupling 110. The small diameter gear 142 is in meshing engagement with the first agitator gear 150 and the second idle gear 160.
The second idle gear 160 is in meshing engagement with the third idle gear 170. The third idle gear 170 is in meshing engagement with the second agitator gear 180. The second idle gear 160 and the third idle gear 170 are configured to transmit the rotation of the first idle gear 140 to the second agitator gear 180.
In accordance with the rotation of the coupling 110 upon receipt of the driving force from the drive shaft of the image-forming apparatus 1, the developing gear 120, the supply gear 130, and the first idle gear 140, which are in meshing engagement with the coupling 110, are caused to rotate. The rotation of the first idle gear 140 in turn causes the first agitator gear 150 and the second idle gear 160 those in meshing engagement with the first idle gear 140 to rotate. In response to the rotation of the second idle gear 160, the third idle gear 170 in meshing engagement therewith rotates. In response to the rotation of the third idle gear 170, the second agitator gear 180 rotates.
In the present embodiment, the developing roller 61 and the supply roller 63 respectively rotate in a counterclockwise direction in
Turning back to
With the developing cartridge 60 thus constructed, the following operational and technical advantages are attainable.
While the image-forming apparatus 1 is operating, the toner accommodated in the casing 62 of the developing cartridge 60 is supplied from the supply roller 63 to the developing roller 61. At this time, the toner in the casing 62 is agitated by the first agitator 30 and the second agitator 40 so as to avoid aggregation of the toner.
Aggregation of toner is likely to occur on the peripheral surface of the supply roller 63. Particularly, in the developing cartridge 60 configured to be attached to the image-forming apparatus 1 such that the developing roller 61 is positioned at a lower portion of the developing cartridge 60, since toner is compressed adjacent to the supply roller 63 due to the gravitational force, toner aggregation may occur on the peripheral surface of the supply roller 63.
In this connection, according to the developing cartridge 60 of the present disclosure, since the second agitator 40 is positioned between the first agitator 30 and the supply roller 63 and the tip end 42A of the blade 42 is configured to contact the peripheral surface of the supply roller 63, the blade 42 scrapes off the toner from the peripheral surface of the supply roller 63. Hence, aggregation of toner on the supply roller 63 can be restrained. Because of determent of occurrence of toner aggregation on the supply roller 63, movement of the aggregated toner toward the developing roller 61 can also be restrained, resulting in prevention of printing blur.
Further, according to the developing cartridge 60 of the present embodiment, damage to the blade 42 can be restrained, since the tip end 42A of the blade 42 does not contact the inner surface 62D of the casing 62.
Further, in the second agitator 40, the blade 42 extends from the shaft 41 toward the upstream side in the rotational direction of the second agitator 40. With this structure, the blade 42 is less likely to come off the shaft 41, compared to a structure where the blade 42 extends from the shaft 41 toward a downstream side in the rotational direction of the second agitator 40.
Further, since the blade 42 is shaped as a film-like sheet, the blade 42 can restrain aggregation of toner on the supply roller 63 without any damage to the supply roller 63.
Further, in the developing cartridge 60 according to the embodiment, the shaft 41 of the second agitator 40 is positioned outside of the rotation locus L3 of the first agitator 30. This structure can prevent mechanical interference between the shaft 41 and the first agitator 30.
Specifically, the shaft 41 is positioned outside of the rotation locus L3 provided by the tip end 32A of the blade 32 of the first agitator 30. Hence, mechanical interference between the shaft 41 of the second agitator 40 and the blade 32 of the first agitator 30 can be prevented.
Various modifications are conceivable.
For example, according to the above-described embodiment, the second agitator 40 includes only one single blade 42. However, the second agitator 40 may include a plurality of blades 42.
As an example,
In the above-described embodiment, the shaft 41 of the second agitator 40 has a triangular cross-section. However, the shaft 41 of the second agitator 40 may have another shape such as a circular cross-section, for example. Still further, the shaft 41 may have a rectangular cross-section, as illustrated in
More specifically,
According to the above-described embodiment, the blade 42 is affixed to the shaft 41. Alternatively, the blade 42 may be fixed to the shaft 41 by screws, for example. Still alternatively, one of the blade 42 and the shaft 41 may have a hole, and remaining one of the blade 42 and the shaft 41 may have a protrusion. The hole and the protrusion may be engaged with each other to fix the blade 42 to the shaft 41. Still alternatively, the shaft 41 may have a groove and the blade 42 may be fitted in the groove to fix the blade 42 to the shaft 41.
According to the above-described embodiment, the blade 42 extends from the shaft 41 toward the upstream side in the rotational direction of the second agitator 40. As an alternative structure,
According to the above-described embodiment, the blade 42 is affixed to the shaft 41. In contrast, in a second agitator 740 according to a sixth modification illustrated in
The developing cartridge 60 is employed as an example of a developing cartridge according to the disclosure. However, the present disclosure may be applied to a process cartridge where a developing cartridge and a drum unit are integral with each other. The present disclosure may also be applied to a developing device configured to receive toner from a toner cartridge storing the toner therein.
Every element described in the embodiment, modifications and variations may be combined with one another as appropriate.
While the description has been made in detail with reference to the embodiments, it would be apparent to those skilled in the art that many modifications and variations may be made thereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2020-023415 | Feb 2020 | JP | national |
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| 20050117920 | Ogata et al. | Jun 2005 | A1 |
| 20120093541 | Komyama et al. | Apr 2012 | A1 |
| 20180181023 | Jang | Jun 2018 | A1 |
| 20200103786 | Ooka et al. | Apr 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 7-325452 | Dec 1995 | JP |
| 2005031299 | Feb 2005 | JP |
| 2012-088403 | May 2012 | JP |
| 2020-052311 | Apr 2020 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20210255567 A1 | Aug 2021 | US |
