Patent Grant
11435678
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2021-074703 (filed on Apr. 27, 2021), the entire contents of which are incorporated herein by reference.
The present disclosure relates to a developing device and an image forming apparatus including the same.
An image forming apparatus using an electrophotographic method, such as a copy machine, a printer, a facsimile, or a multi-functional peripheral having functions thereof, includes a developing device for forming a toner image (a developer image) by developing an electrostatic latent image formed on an outer circumferential surface of an image carrier, namely, by visualizing the electrostatic latent image.
The developing device includes a developing container for containing a developer including a toner and a developer carrier that is disposed in contact with or adjacently to the image carrier and carries a developer. The developing container has a container opening that is open to a downstream side of the developing device with respect to a moving direction of the developing device. The developer carrier is disposed so as to overlap the container opening. A part of the developer carrier is exposed to an outer side of the developing device through the container opening. The developer carrier is capable of carrying, on an outer circumferential surface thereof, the toner in the developing container, The toner in the developing container is supplied to the image carrier through the exposed part of the developer carrier.
As such a developing device, there is a type including a sheet-shaped seal member provided at a gap between a lower part of the outer circumferential surface of the developer carrier and a lower edge part of the container opening. The seal member is disposed on an inner surface of the developing container along a rotary shat direction (a longitudinal direction) of the developer carrier and closes the gap between the lower part of the outer circumferential surface of the developer carrier and the edge part of the container opening, thus suppressing an outflow of the developer through the gap.
Furthermore, a pair of pressing members is provided at respective gaps between both end parts of the developer carrier in the rotary shaft direction and the developing container. The pressing members protrude from the inner surface of the developing container toward the outer circumferential surface of the developer carrier so as to make contact with and press the outer circumferential surface of the developer carrier at the both end parts thereof. As a result of making contact with the developer carrier, the pressing members are compressed toward an opposite side to the developer carrier. The pressing members make contact with and press the outer circumferential surface of the developer carrier in this manner, thus closing the gaps between the developing container and the developer carrier to suppress outflow of the developer. Both end parts of the above-described seal member along the rotary shaft direction are interposed in respective gaps between the pressing members and the developer carrier.
The developing device configured as above is demountably mounted in a main body (hereinafter, referred to as an “apparatus main body”) of the image forming apparatus. The apparatus main body has a main body opening that is open upward. Inside the apparatus main body, a guide rail is provided to guide the developing device from the main body opening to a mounting position of the developing device. The guide rail extends downward from the main body opening to the mounting position. The developing device is movable in the apparatus main body along the guide rail.
A developing device according to one aspect of the present disclosure includes a developing container, a developer carrier, a seal member, and a pair of pressing members. The developing container has an opening and contains inside a developer including a toner. The developer carrier is rotatably supported to the developing container and has an outer circumferential surface carrying the developer, a part of the outer circumferential surface being exposed through the opening. The seal member is disposed along a rotary shaft direction of the developer carrier and closes a gap between the developer carrier and the opening. The pair of pressing members makes contact with both end parts of the developer carrier in the rotary shaft direction and the seal member so as to close respective gaps between the both end parts of the developer carrier and the developing container. The seal member includes a contact end part that is one of end edges of the seal member in a longitudinal direction thereof on a side near the developer carrier, the seal member making contact with an entire region of the outer circumferential surface of the developer carrier in the rotary shaft direction, a first blocking part that protrudes upward over an entire region of another of the end edges of the seal member on a side distant from the developer carrier, and an interposed end part that is interposed between each of the both end parts of the developer carrier and a corresponding one of the pressing members and is an end edge of the seal member orthogonal to the contact end part. In the developing device, each of the pressing members has a pressing surface that is radially opposed to the outer circumferential surface of the developer carrier, and in the pressing surface, a cutout recess that is a radially concave cutout is formed to extend from an end part of the pressing surface on a side near the opening in a circumferential direction of the developer carrier to a center of the pressing surface in the circumferential direction. The developing container includes a second blocking part that is adjacent to each of both end parts of the first blocking part in the rotary shaft direction and protrudes upward. The interposed end part is located at such a position as to overlap the cutout recess with respect to the circumferential direction, and the second blocking part is located at such a position as to overlap the cutout recess with respect to the rotary shaft direction.
With reference to the appended drawings, the following describes an embodiment of the present disclosure.
As shown in
In the main body housing 10, a front cover 11, a rear cover 12, a main body opening 15, and an upper cover 16 are provided. The front cover 11 is positioned on a front surface side of the main body housing 10. The rear cover 12 is positioned on a rear surface side of the main body housing 10. The main body opening 15 is formed on an upper side in the main body housing 10. The upper cover 16 is provided on an upper surface of the main body housing 10. The upper cover 16 is used to enable opening and closing of the main body opening 15. When the upper cover 15 is opened, there is provided access to inside the main body housing 10 through the main body opening 15.
On an upper surface of the upper cover 16, a paper discharge portion 13 is provided to which a sheet (a recording medium) after being subjected to image formation is discharged. At an upper part of the main body housing 10, a paper discharge port 14 is provided to be opposed to the paper discharge portion 13 in a front-rear direction. The paper discharge port 14 is an opening communicating with an inside of the housing 10. In the following description, the term “sheet” refers to a copy sheet, coated paper, an OHP sheet, a cardboard, a postcard, tracing paper, or any other sheet material to be subjected to image forming processing.
In a state where the upper cover 16 is opened, the developing device 33 is removable and insertable through the main body opening 15. In a state where the rear cover 12 is opened, various units (other than the developing device 33) included in the image forming portion 30 and the fixing portion 40 are removable and insertable from the rear surface side of the main body housing 10.
The paper feed portion 20 includes a paper feed cassette 21. The paper feed cassette 21 contains sheets to be subjected to image forming processing. A part of the paper feed cassette 21 protrudes forward beyond a front surface of the main body housing 10. An upper surface of the other part of the paper feed cassette 21 housed in the main body housing 10 is covered with a paper feed cassette top plate 21U.
In the paper feed cassette 21, a sheet containing space for containing a stack of sheets therein, a lift plate for lifting the stack of sheets so as to feed the sheets, and so on are provided. A sheet feed-out part 21A is provided at an upper part of the paper feed cassette 21 on a rear end side thereof. In the sheet feed-out part 21A, there is disposed a paper feed roller 21B for feeding out one by one a topmost one of the stack of sheets in the paper feed cassette 21.
The image forming portion 30 performs an image forming operation. The image forming operation refers to an operation of forming a toner image (a developer image) on a sheet fed out from the paper feed portion 20. The image forming portion 30 includes, in addition to a photosensitive drum 31, a charging portion 32, an exposure portion 35, the developing device 33, and a transfer roller 34, which are disposed around the photosensitive drum 31. As a developer used for image formation, there is used a non-magnetic single-component developer formed only of a toner.
The photosensitive drum 31 (an image carrier) includes a rotary shall and an outer circumferential surface that rotates about the rotary shaft. On the outer circumferential surface of the photosensitive drum 31, there is formed a photosensitive layer that is made of, for example, a known organic photoconductor (OPC) and composed of an electric charge generation layer, an electric charge transport layer, and so on. The photosensitive layer is uniformly charged by the after-mentioned charging portion 32, after which light is applied thereto by the exposure portion 35 so that an electrostatic latent image with attenuated electrostatic charge is formed thereon, which is then visualized by the developing device 33 into a toner image, and thus the toner image is carried on the photosensitive layer.
The charging portion 32 (a charging device) is disposed at a prescribed distance from the outer circumferential surface of the photosensitive drum 31 and uniformly charges the outer circumferential surface of the photosensitive drum 31 without making contact therewith. Specifically, the charging portion 32 includes a charge wire 321 and a grid electrode 322 (each of which is shown in
The charging portion 32 passes an electric current having a prescribed electric current value through the charge wire 321 so that a corona discharge is generated, and also applies a prescribed voltage to the grid electrode 322 so that a part of the outer circumferential surface of the photosensitive drum 31 opposed to the grid electrode 322 is uniformly charged to a prescribed surface potential.
The exposure portion 35 (an exposure device) includes a laser light source and optical system equipment such as a mirror and a lens. The exposure portion 35 applies light modulated based on image data given from an external device such as a personal computer to the outer circumferential surface of the photosensitive drum 31. In this manner, the exposure portion 35 forms an electrostatic latent image corresponding to an image based on the image data on the outer circumferential surface of the photosensitive drum 31.
The transfer roller 34 includes a rotary shaft parallel to a sheet width direction and an outer circumferential surface opposed to the outer circumferential surface of the photosensitive drum 31. The transfer roller 34 is supported to the main body housing 10 so as to be rotatable about the rotary shaft. The transfer roller 34 transfers a toner image carried on the outer circumferential surface of the photosensitive drum 31 to a sheet passing through a nip between itself and the outer circumferential surface of the photosensitive drum 31. At the time of the transfer, a transfer voltage of a polarity opposite to that of a toner is applied to the transfer roller 34.
The fixing portion 40 is positioned downstream relative to the transfer roller 34 in a sheet conveyance direction and fixes, on a sheet, a toner image that has been transferred thereon. The fixing portion 40 includes a fixing roller 41 and a pressing roller 42. The fixing roller 41 includes inside a heating source and heats a toner transferred on a sheet to a prescribed temperature. The pressing roller 42 is brought into pressure contact with the fixing roller 41 so as to form a fixing nip between itself and the fixing roller 41. When a sheet on which a toner image has been transferred is passed through the fixing nip, the toner image is heated by the fixing roller 41 and pressed by the pressing roller 42 and thus is fixed on the sheet.
In the main body housing 10, a main conveyance path 22F and a reverse conveyance path 22B are provided. The main conveyance path 22F and the reverse conveyance path 22B are used to convey a sheet. The main conveyance path 22F extends from the sheet feed-out part 21A of the paper feed portion 20 to the paper discharge port 14 via the image terming portion 30 and the fixing portion 40. In a case where double-sided printing is performed on a sheet, the reverse conveyance path 22B is used to convey the sheet whose one side has already been subjected to printing back to an upstream side of the image forming portion 30 in the main conveyance path 22F.
The main conveyance path 22F extends to pass upward from below through a transfer nip formed by the photosensitive drum 31 and the transfer roller 34, Furthermore, a registration roller pair 23 is disposed on an upstream side relative to the transfer nip in the main conveyance path 22F. A sheet is once stopped from being conveyed at the registration roller pair 23 so as to be subjected to skew correction and then is fed out to the transfer nip at prescribed timing for image transfer. A plurality of conveyance rollers for conveying a sheet is disposed in each of the main conveyance path 22F and the reverse conveyance path 22B. A paper discharge roller pair 24 is disposed in the vicinity of the paper discharge port 14.
The reverse conveyance path 22B is formed between an outer side surface of a reversing unit 25 and an inner surface of the rear cover 12 of the main body housing 10. The transfer roller 34 and one of rollers constituting the registration roller pair 23 are mounted to an inner side surface of the reversing unit 25. The rear cover 12 and the reversing unit 25 are pivotable about an axis of a fulcrum 121 provided at their lower ends. At the occurrence of a jam (a paper jam) in the reverse conveyance path 22B, the rear cover 12 is opened. At the occurrence of a jam in the main conveyance path 22F or in a case of taking out a unit of the photosensitive drum 31 or the developing device 33 to the outside, in addition to the rear cover 12, the reversing unit 25 is also opened.
As shown in
As shown in
The developing container 36 contains inside a non-magnetic single-component developer formed only of a toner and houses the developing roller 37, the supply roller 38, and so on. The developing container 36 has a stirring chamber 335, a container opening 60 (an opening), and the bush cover 63 (a cover member). The stirring chamber 335 contains a developer in a stirred state.
The container opening 60 is positioned on a rear side relative to the stirring chamber 335 with respect to the front-rear direction. The container opening 60 is a rectangular through hole open to a rear side (a side near the photosensitive drum 31) of the developing container 36. The container opening 60 is formed to be elongate in a width direction (an axis direction) of the developing device 33.
The developing roller 37 is provided on an inner side of the container opening 60 so as to overlap the container opening 60. A part of an outer circumferential surface of the developing roller 37 is exposed to an outer side of the developing container 36 through the container opening 60. The developing roller 37 includes a rotary shaft 39 extending along the width direction (the sheet width direction) of the developing device 33. The rotary shaft 39 is rotatably supported to the developing container 36. In other words, the developing roller 37 is supported to the developing container 36 via the rotary shaft 39 so as to be rotatable about the rotary shaft 39. Hereinafter, a direction alone the rotary shaft 39 is referred to as the “axis direction.”
The developing roller 37 is capable of carrying a toner on the outer circumferential surface thereof. When the developing device 33 is at the mounting position P1, the part of the developing roller 37 exposed through the container opening 60 is opposed to the outer circumferential surface of the photosensitive drum 31 while being in contact therewith or being adjacent thereto. In this state, the developing roller 37 is capable of supplying a non-magnetic single-component toner (developer) to the photosensitive drum 31.
The supply roller 38 is provided between the developing roller 37 and the stirring paddle 333. The supply roller 38 supplies a non-magnetic single-component toner (developer) to the outer circumferential surface of the developing roller 37. The stirring paddle 333 is provided in the stirring chamber 335 and stirs a developer inside the stirring chamber 335.
The bush cover 63 is removably mounted at each of both end parts of the developing container 36 with respect to the sheet width direction. The bush cover 63 constitutes each of side walls of the developing container 36. As shown in
The developing roller support hole 54 has an inner diameter larger than a diameter of the rotary shaft 39 of the developing roller 37. The rotary shaft 39 is inserted into the developing roller support hole 54 and is supported so as to be rotatable with respect to the bush cover 63. The supply roller support hole 55 has an inner diameter larger than a diameter of a rotary shaft 57 (see
A positioning protrusion 47 and a plurality of cutouts 59 are provided at each of end parts of the developing container 36 on outer sides thereof in the axis direction. The positioning protrusion 47 protrudes outward in the axis direction from the developing container 36. Positioning of the bush cover 63 is achieved by inserting the positioning protrusion 47 into the positioning hole 56.
The cutouts 59 are recesses that are concave along the axis direction. The engagement parts 58 protrude along the axis direction from a surface of the bush cover 63 on a side toward the developing container 36 with respect to the axis direction. A claw shape is formed at a distal end of each of the engagement parts 58 in a protruding direction thereof. Each of the engagement parts 58 is inserted into a corresponding one of the cutouts 59 and is engaged therewith by use of the claw shape. Each of the engagement parts 58 and a corresponding one of the cutouts 59 form a so-called snap-fit structure, and thus the bush cover 63 is mounted to the developing container 36.
Referring back to
In a state of being mounted at the mounting position P1 in the main body housing 10, the developing device 33 supplies a toner to the outer circumferential surface of the photosensitive drum 31. In this manner, the developing device 33 develops an electrostatic latent image formed on the outer circumferential surface of the photosensitive drum 31 (forms a toner image (a visible image) by visualizing the electrostatic latent image).
As shown in
As shown in
The pressing member 43 is located at such a position as to overlap each of end parts of the container opening 60 on both sides thereof with respect to the axis direction (see
The first stacking component 50 is a polytetrafluoroethylene (so-called Teflon) sheet body having a prescribed thickness. The first stacking component 50 is radially opposed to the developing roller 37 and makes contact with an outer circumferential surface of each of both end parts 66 of the developing roller 37. The first stacking component 50 has a pressing surface 44. The pressing surface 44 is formed to be curved so as to be concave forward (toward the supply roller 38) along the outer circumferential surface of the developing roller 37 (see
The second stacking component 51 is stacked on a surface of the first stacking component 50 on an opposite side to the pressing surface 44 with respect to the radial direction. The first stacking component 50 and the second stacking component 51 are bonded to each other with an adhesive or the like. The second stacking component 51 is secured to an inner surface of the developing container 36 with an adhesive or the like. The second stacking component 51 is made of expanded urethane such as sponge. The second stacking component 51 has a thickness larger than that of the first stacking component 50.
The pressing member 43 includes a cutout recess 52 formed therein. In the cutout recess 52, the pressing member 43 is radially concave in a region extending from the pressing surface 44 to the second stacking component 51. With respect to a circumferential direction of the developing roller 37, the cutout recess 52 is formed as a cutout extending from an end part of the pressing member 43 on a side near a first blocking part 19 (which will be detailed later) to a center part of the pressing member 43. The cutout recess 52 is formed by cutting out only the first stacking component 50. A part of the second stacking component 51 overlapping the cutout recess 52 extends beyond the first stacking component 50 with respect to the circumferential direction of the developing roller 37.
The pressing member 43 is formed to have a thickness (a total of a thickness of the first stacking component 50 and a thickness of the second stacking component 51) larger than a gap between the outer circumferential surface of the developing roller 37 and the inner surface of the developing container 36. When the developing roller 37 is mounted in the developing container 36, the pressing surface 44 makes contact with the outer circumferential surface of each of the both end parts 66 of the developing roller 37, and thus the pressing member 43 is pressed by the each of the both end parts 66. Under this pressing force, the first stacking component 50 is compressed outward in the radial direction of the developing roller 37 (see
Referring back to
The seal member 65 is a rectangular sheet formed of a PET film or the like. The seal member 65 is stacked on the flat part 62 and bonded to the developing container 36 with an adhesive or the like. The seal member 65 is formed to be elongate in the axis direction. The seal member 65 extends between the both end parts 66 of the developing roller 37 along the axis direction.
The seal member 65 includes a contact end part 67, the first blocking part 19, and an interposed end part 68. The contact end part 67 is one of both end edges of the seal member 65 in the front-rear direction (a direction orthogonal to the sheet width direction) on a side near the developing roller 37 (the supply roller 38). The first blocking part 19 rises up from the other end edge of the seal member 65 on a side distant from the developing roller 37 (the supply roller 38) along a surface direction of the seal member 65. The interposed end part 68 constitutes each of both end edges of the seal member 65 with respect to the axis direction.
The contact end part 67 is positioned between the developing container 36 and the developing roller 37. The contact end part 67 is in contact with an entire developer-carrying region of the outer circumferential surface of the developing roller 37 with respect to the axis direction. As a result of the contact end part 67 being in contact with the outer circumferential surface of the developing roller 37, the seal member 65 closes a gap between the developing container 36 and the developing roller 37, thus suppressing outflow of a developer in the developing container 36.
The first blocking part 19 is made of sponge or the like and has a quadrangular shape. The first blocking part 19 is bonded to a surface of the seal member 65 with an adhesive or the like. The first blocking part 19 retains a slight amount of developer that has flowed out through a gap between the developing roller 37 and the developing container 36, thus preventing it from dropping outside the developing device 33.
As shown in
On an outer side of each of both end parts of the first blocking part 19 with respect to the axis direction, a plate-shaped second blocking part 53 is provided to protrude upward. The second blocking part 53 is integrally formed with the bush cover 63. In a state where the bush cover 63 is mounted to the developing container 36, the second blocking part 53 extends from the bush cover 63 to approach the first blocking part 19 along the axis direction. Furthermore, in this state, the second blocking part 53 is located at such a position as to overlap the cutout recess 52 with respect to the axis direction.
As shown in
According to the configuration of the foregoing embodiment, the developing roller 37 makes contact with the seal member 65 and the pressing member 43, and thus a gap between the developing roller 37 and the developing container 36 is closed. Furthermore, a part of the pressing member 43 in which the cutout recess 52 is formed is radially concave. That is, the pressing member 43 has a smaller radial thickness in the part in which the cutout recess 52 is formed than in other parts thereof. Thus, in a state where the first stacking component 50 is compressed by the developing roller 37, resilience of the first stacking component 50 is also smaller at a periphery of the cutout recess 52 than in other parts thereof. The interposed end part 68 of the seal member 65 is located at such a position as to overlap the cutout recess 52, and thus resilience of the pressing member 43 acting on the interposed end part 68 is relatively reduced. As a result, a part of the seal member 65 extending from a center part thereof to the interposed end part 68 in the axis direction is unlikely to be deformed, and thus it is possible to suppress generation of a gap between this part and the developing container 36 or the developing roller 37. Consequently, it is possible to more efficiently suppress outflow of a developer in the developing container 36.
Furthermore, the second blocking part 53 is located at such a position as to overlap the cutout recess 52 with respect to the axis direction. Thus, even if a slight amount of developer flows out from between the interposed end part 68 and either of the developing container 36 and the developing roller 37, the slight amount of developer that has flowed out is blocked from flowing out to outside the developing device 33 by the second blocking part 53. Consequently, it is possible to more effectively suppress outflow of a developer to outside the developing device 33.
Moreover, the first blocking part 19 is provided to protrude upward over an entire region of the end edge of the seal member 65 in a longitudinal direction thereof. Thus, even if a waste toner is deposited at a periphery of the container opening 60, when the developing device 33 faces downward at the time of being mounted in the main body housing 10, the waste toner at the periphery of the container opening 60 is held back by the first blocking part 19. Consequently, it is possible to suppress dropping of a waste toner into the main body housing 10.
Accordingly, it is possible to provide the developing device 33 capable of suppressing dropping of a developer from a periphery of the container opening 60 of the developing device 33 into the main body housing 10, while suppressing outflow of the developer from a gap between the developing roller 37 and the developing container 36.
Furthermore, as described above, the second blocking part 53 is integrally formed with the bush cover 63. Thus, upon mounting of the bush cover 63, positioning of the second blocking part 53 at a prescribed position is also achieved. As a result, it is possible to reduce man-hours for fabrication and thus to reduce a manufacturing cost.
Other than the above, the present disclosure is not limited to the foregoing embodiment and can be variously modified without departing from the spirit of the present disclosure. For example, while the foregoing embodiment describes a monochrome printer as an example of the image forming apparatus 1, the present disclosure is applicable also to, for example, a tandem color printer or a rotary color printer. Furthermore, the present disclosure is applicable also to an image forming apparatus such as a copy machine, a facsimile, or a multi-functional peripheral having functions thereof.
Furthermore, while in the foregoing embodiment, the second blocking part 53 is integrally formed with the bush cover 63, without being limited thereto, for example, the second blocking part 53 can also be integrally formed with a different part of the developing container 36 than the bush cover 63.
Furthermore, while in the foregoing embodiment, the first blocking part 19 is made of sponge, without being limited thereto, the first blocking part 19 may be made of any other material. Furthermore, the first blocking part 19 can also be configured to be integrally formed with the seal member 65 and bent so as to rise upward from the end edge of the seal member 65. In this case, the number of components of the seal member 65 is reduced, and thus a manufacturing cost can be reduced.
Furthermore, while in the foregoing embodiment, a non-magnetic single-component developer formed only of a toner is used as a developer, it is also possible to employ a two-component developer using a toner and a carrier.
The present disclosure is usable in an image forming apparatus including a developing device that uses a developer including a toner to perform development. Through the use of the present disclosure, it is possible to provide an image forming apparatus capable of suppressing dropping of a developer from a periphery of an opening of a developing device into a main body of the image forming apparatus at the time when the developing device is mounted in the image forming apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2021-074703 | Apr 2021 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20160259266 | Uno | Sep 2016 | A1 |
| 20180292769 | Matsuzaki | Oct 2018 | A1 |
| 20190361372 | Kim | Nov 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 2010-164736 | Jul 2010 | JP |
