Patent Grant
7319832
This application claims priority from Japanese Patent Application No. 2004-162430, filed on May 31, 2004, the entire subject matters of the application are incorporated herein by reference.
1. Technical Field
Aspects of the invention relate to an image forming device that forms an image in accordance with an electrophotographic imaging process, and a process cartridge employed in such an image forming device.
2. Related Art
Conventionally, image forming devices that form images in accordance with the electrophotographic image formation process have been known. Typically, such an image forming device has a main body provided with a transfer roller, and a process cartridge detachably attached to the main body. The process cartridge includes a photoconductive drum, and when the process cartridge is attached to the main body of the image forming device, the photoconductive drum and the transfer roller face are press-contacted with each other. In such an imaging device, in a process of detaching/attaching the process cartridge with respect to the main body, the photoconductive drum and the transfer roller may slide-contact each other. In such a case, the surface of the photoconductive drum may be deteriorated and quality of the formed image may be lowered.
To avoid the above problem, Japanese Patent Provisional Publication No. HEI 11-52814 discloses a structure for switching the photoconductive drum and the transfer roller between a press-contacted state and a separated state when a drum unit (i.e., the process cartridge) in response to operation of a lever. When such a structure is employed, by detaching/attaching the drum unit after they are separated, the slide-contact between the photoconductive drum and the transfer roller can be avoided.
In order to realize the structure disclosed in the above-identified publication, a relatively complicated structure including a cam mechanism should be employed. Further, an additional operation of the handle is necessary, which make operability in detaching/attaching the drum unit worse.
Aspects of the present invention are advantageous in that an improved image forming device and a process cartridge are provided, with which the process cartridge can be attached/detached without the slide-contact between the photoconductive drum and the transfer roller with a relatively simple structure.
The following describes general aspects of the invention that may or may not be included in various embodiments/modifications. Also, it is noted that various connections are set forth between elements in the following description. It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect.
According to some aspects of the invention there is provided an image forming device, which is provided with a process cartridge having a image carrying member, a main body including an attaching section to which the process cartridge is detachably attached, and an image transfer member to be press-contacted to the image carrying member for image transfer when the process cartridge is completely attached to the attaching section. The the process cartridge may be configured to apply a pressing force to the attaching section when process cartridge is not completely attached to the attaching section, and the image forming device may further include a separating mechanism configured to allow the press-contact between the image carrying member and the image transfer member when the process cartridge is completely attached to the attaching section, the separating mechanism operating to separate the image carrying member and the image transfer member when the pressing force is applied by the process cartridge to the attaching section.
It should be note that the image carrying member may include not only a photoconductive drum, but an intermediate transfer member. Further, the term “image forming device” should not be limited to a printer or a laser printer. The image forming device may include various type of devices such as a facsimile device and an MFP (Multi Function Periphal) having functions of a printer and a facsimile. The term “not completely attached” means any state other that the state where the image transfer member and the image carrying member are contact each other.
Optionally, the pressing force may not be applied to the attaching section when the process cartridge is completely attached to the attaching section.
The main body may include a supporting member that supports the transfer member, and an urging member that urges the supporting member in a direction where the image transfer member is urged toward the image carrying member. The separating mechanism may move the supporting member against the urging force of the urging member to separate the image transfer member from the image carrying member.
The process cartridge may be moved, for attachment/detachment, in a direction substantially perpendicular to a direction in which the image carrying member and image transfer member face each other when the process cartridge is completely attached to the attaching section.
Optionally, the transfer member may transfer an image carried by the image carrying member on a recording medium fed on the image transfer member, and the process cartridge is moved in a direction parallel with the feeding direction of the recording medium when attached to or detached from the attaching section.
Further optionally, the process cartridge may be moved to rotate about an axis that is parallel with a plane on which the image carrying member and the image transfer member are to be press-contacted so as to be completed attached to the attaching section.
The image carrying member and the image transfer member may have rotatable rollers having rotary axes extending in a predetermined same direction, respectively. The rollers may be provided with gears that engage with each other when the process cartridge is completely attached to the attaching section, and the gears of the rollers may be disengaged when the process cartridge is not completely attached to the attaching section.
Optionally, the image forming device may include a positioning structure that adjusts positions of the image carrying member and the image transfer member when the process cartridge is completely attached to the attaching section.
The separating mechanism may further include a protruded portion provided to one of the facing portions of the process cartridge and the main body, and a dent portion provided to the other of the facing portions of the process cartridge and the main body. The press-contact between the image carrying member and the image transfer member may be allowed when the protruded portion enters the dent portion as the process cartridge is completely attached to the attaching section, and the image carrying member and the image transfer member may be separated when the protruded portion interferes with a portion next to the dent portion as the process cartridge is not completely attached to the attaching section.
In the above case, the main body may be provided with a supporting member that supports the transfer member, and an urging member that urges the supporting member in a direction in which the image transfer member faces the image carrying member. Further, the protruded portion may be provided to the supporting member, and the dent portion may be provided to the process cartridge.
Optionally, the protruded portion may be provided to the process cartridge, the protruded portion being protruded outward with respect to an outermost portion of the image carrying member.
Still optionally, the dent portion may be defmed as a portion between two protruded sections, a relative position between the image carrying member and the image transfer member in a direction in which to protruded sections are arranged being adjusted by the two protruded sections when the protruded portion engages with the dent portion as the process cartridge is completely attached to the attaching section.
At least one of the protruded portion and the dent portion may be formed with a tapered surface which enables the image carrying member and the image transfer member to gradually approach when an attaching state of the process cartridge is changes from a non-attached state to a completely attached state.
According to other aspects of the invention, there is provided a process cartridge to be detachably attached to an attaching section of a main body of an image forming device, the process cartridge comprising a image carrying member which is to be press-contacted with an image transfer member provided to the main body when the process cartridge is completely attached to the attaching section. A protruded portion may be provided to one of the facing portions of the process cartridge and the main body, and a dent portion may be provided to the other of the facing portions of the process cartridge and the main body. Further, the press-contact between the image carrying member and the image transfer member may be allowed when the protruded portion enters the dent portion as the process cartridge is completely attached to the attaching section, and the image carrying member and the image transfer member may be separated when the protruded portion interferes with a portion next to the dent portion as the process cartridge is not completely attached to the attaching section.
According to another aspect of the invention, there is provided a process cartridge to be detachably attached to an attaching section of a main body of an image forming device. The process cartridge may include a image carrying member which is to be press-contacted with an image transfer member provided to the main body when the process cartridge is completely attached to the attaching section, and a dent portion in which a protruded portion provided to the main body is inserted when the processing cartridge is completely attached to the attaching section, the image carrying member being press-contacted when the protruded portion is inserted in the dent portion. The protruded portion contacting side portions defining the dent portion when the processing cartridge may not be completely attached to the attaching section, the image carrying member and the image transfer member being spaced from each other when the protruded portion contacts the side portions defining the dent portion.
Optionally, the protruded portion and the dent portion may not contact each other when the process cartridge is completely attached to the attaching section.
Further optionally, the process cartridge may be moved to be attached to or detached from the main body along a direction perpendicular to a direction in which the image carrying member and the image transfer member face each other when the process cartridge is completely attached to the attaching section.
In this case, the process cartridge may be inserted to the attaching section along a direction parallel with a feeding direction of a recording medium fed on the image transfer member.
Optionally, the process cartridge may be attached to the attaching section by a rotation about a side end thereof.
The image carrying member and the image transfer member may respectively have rotatable rollers having rotary axes extending in a predetermined same direction. Further, the rollers are provided with gears that engage with each other when the process cartridge may be completely attached to the attaching section, and the gears of the rollers are disengaged when the process cartridge may not be completely attached to the attaching section.
Further optionally, the protruded portion and the dent portion may be shaped to engage with each other when the process cartridge is completely attached to the attaching section, and a positional relationship between the image carrying member and the image transfer member in a direction in which a recording medium is fed on the image transfer member may be adjusted by the engagement between the protruded portion and the dent portion.
Optionally, at least one of the protruded portion and the dent portion may be formed with a tapered surface which enables the image carrying member and the image transfer member to gradually approach when an attaching state of the process cartridge is changed from a non-attached state to a completely attached state.
According to a further aspect of the invention, there is provided an image forming device, which is provided with a process cartridge having an image carrying member, a main body having including an attaching section to which the process cartridge is detachably attached, an image transfer member supported at the main body, the image transfer member being movable between a first position where the image transfer member is contacted to the image carrying member and a second position where the image transfer member is separated from the image carrying member, and a separating mechanism that communicates with the process cartridge and makes the image transfer member positioned at the second position when the process cartridge is adjacent to the attaching section while the process cartridge is being attached to and being detached from the attaching section.
Hereinafter, referring to the accompanying drawings, laser beam printers according to first through third embodiments and modifications thereof will be described in detail. It is noted that, in the following description, a right-hand side of
According to the first embodiment, a process cartridge 12 and a transfer roller 26 are separate members. The transfer roller 26 is fixedly provided inside a main body 1a of the laser printer 1, while the process cartridge 12 is detachably attached to the casing 1a. Further, on a front surface of the casing 2 (i.e., the right-hand side of the casing 2 in
The feeder unit 4 includes, on a bottom surface of the casing 2, a sheet feed tray 43 which can be detachably mounted, a sheet pressing plate 6 provided inside the sheet feed tray 43, a sheet feed roller 7 and a sheet separation pad 8 which are provided on an upper portion of the leading end portion of the sheet feed tray 43, and a register roller 9 provided on a downstream side, in the sheet feed direction, with respect to the sheet feed roller 7.
The pressing plate 6 is configured such that a plurality of recording sheets 3 are placed thereon in a stacked state, and an end farther from the sheet feed roller 7 is rotatably supported, while the other end closer to the sheet feed roller 7 is rockable in an up and down direction. The pressing plate 6 is urged upward by a spring member (not shown) provided below the pressing plate 6. Therefore, as the stacked amount of the recording sheets 3 increases, the pressing plate 6 rocks downward against the urging force of the spring member, about the side of the pressing plate 6 farther from the sheet feed roller 7. The sheet feed roller 7 and the sheet separation pad 8 are arranged to face each other. By a spring 10 provided on a lower surface of the separation pad 8, it is urged toward the sheet feed roller.
The uppermost sheet 3 of the stack of recording sheets 3 stacked on the sheet pressing plate 6 is press-contacted with the sheet feed roller 7 by the urging force of the spring member (not shown) provided below the pressing plate 6. As the feed roller 7 rotates, the recording sheet 3 is nipped between the sheet feed roller 7 and the sheet separation pad 8, and thereafter, the recording sheets 3 are fed one by one. The recording sheet 3 thus fed is introduced to the register rollers 9. The register rollers 9 include a driving roller 44 provided in the casing 2, and a driven roller 12 provided to a process cartridge. Specifically, the recording sheet 3 fed from the sheet feed roller 7 is nipped between the driving roller 44 and driven roller 45. The position of the recording sheet 3 is adjusted, and then fed to the image forming unit 5.
The image forming unit 5 has a scanner unit 11, a process cartridge 12, a transfer roller 26, and a transfer unit 13.
The scanner unit 11 is provided in an upper portion of the casing 2, and is provided with a laser source (not shown), a polygonal mirror 14 which is driven to rotate, lenses 15 and 16, mirrors 17, 18 and 19. The laser source 11 emits a laser beam, which is emitted based on image data, is transmitted through or reflected by the polygonal mirror 14, a lens 15, mirrors 17 and 18, a lens 16, a reflector 19 in this order so that the laser beam is finally incident on the photoconductive drum 21 of the process cartridge 12 as a high speed scanning beam.
As shown in
Nonmagnetic single-component toner having a positive charging characteristic is filled in the toner box 27 as developing agent. Specifically, polymerized toner created by copolymerizing polymerized monomer (such as styrene monomer, or acrylic monomer such as acrylic acid, alkyl acrylates, alkyl meta-acrylates) in accordance with a well-known polymerizing method such as suspension polymerizing method may be used.
The polymerized toner has ball-like particles and high flowability. Typically, a coloring agent such as carbon black and/or wax is added. Further, in order to improve the flowability, an additional agent such as silica may be added. The size of the particle is approximately in the range from 6 μm to 10 μm.
The toner in the toner box 27 is agitated by an agitator 29 supported by a rotary shaft 28, which is provided at the center of the toner box 27. The toner as agitated is discharged from a toner supply opening 30 formed on a side portion of the toner box 27 (see
On a side portion of the toner supply opening 30, a supply roller 24 is provided. The supply roller 24 is rotatable in clockwise direction (in
The supply roller 24 is configured such that a metallic roller shaft is covered with a layer of a roller formed of electrically-conductive porous member. The developing roller 22 is configured such that a metallic roller shaft is covered with a layer of a roller formed of electrically-conductive rubber member. Specifically, the roller portion of the developing roller 22 may include a roller body formed of conductive urethane rubber or silicon rubber including fme carbon particles. On the roller body described above, a coating layer formed of urethane rubber or silicon rubber including fluorine may be used. It should be noted that a bias voltage is applied to the developing roller 22 so that it has a predetermined electrical potential with respect to the photoconductive drum 21.
Adjacent to the developing roller 22, a layer thickness regulating blade 23 is provided. The regulating blade 23 includes a blade member 37 formed of a metallic plate spring and a pressing member 38, which is formed of insulating silicon rubber and formed to have a half round cross-sectional shape. A portion of the blade 37, opposite to a portion contacting the pressing member 38, is supported by the developing cartridge 36 at a position adjacent to the developing roller 22. Further, the pressing member 38 is press-contacted against the developing roller 22 by an elastic force of the blade member 37.
The toner discharged from the toner supply opening 30 is, as the supply roller 24 rotates, supplied to the developing roller 22. When the toner is supplied between the supply roller 24 and the developing roller 22, the toner is charged as frictional electrification occurs at that location. That is, the toner supplied onto the developing roller 22 enters a nip between the pressing member 38 and the developing roller 22 as the developing roller 22 rotates and sufficiently charged by friction at that location. The charged toner is carried by the developing roller 22 as a thin layer having a predetermined thickness.
The photoconductive drum 21 is located at a rear side of the developing roller 22 and faces the developing roller 22 with a predetermined clearance therebetween. The photoconductive drum 22 is rotatable in a clockwise direction in
The corona charger 25 is arranged above the photoconductive drum 21 with a predetermined distance therebetween so that it does not contact the photoconductive drum 21.
The corona charger 25 is a charger for the positive electrification, and generates a corona discharge from an electrifying wire such as a tungsten wire. As the corona charger 25 is actuated, the circumferential surface of the photoconductive drum 21 is evenly charged to a positive polarity.
After the above charging is effected (i.e., when the circumferential surface of the photoconductive drum 21 is evenly charged), the circumferential surface of the photoconductive drum 21 is exposed to a scanning laser beam, which scans at a high speed, thereby forming on the circumferential surface of the photoconductive drum 21 an electrostatic latent image according to image data. As the developing roller 22 rotates, the toner positively electrified and carried by the developing roller 22 is attracted by the latent image on the photoconductive drum 21 when the developing roller 22 contacts the photoconductive drum 21. That is, the portion of the latent image on the photoconductive drum 21 has a lower potential in comparison with the other portion, which is uniformly charged, of the photoconductive drum 21, and the toner is supplied from the developing roller 22 to the latent image of the circumferential surface of the photoconductive drum 21. With this process, the latent image is developed to a toner image.
Between side walls 20a of the drum cartridge 20, a brush unit 52 is provided. The brush unit 52 includes a brush holder 53 which is bridged between the side walls 20a and a brush 54. The brush holder 53 also supports a brush supporting plate 51. The brush supporting plate 51 serves to support the brush 54 from the below thereof. The brush 54 is made of electrically conductive material. A bias voltage generated by a high-voltage source (not shown) provided in the main body 1a is applied to the brush 54, thereby removing minute paper particles adhered on the circumferential surface of the photoconductive drum 21.
The transfer roller 26 is configured such that a metallic roller shaft 26a is covered with a roller 26b made of electrically conductive rubber material, the both end portions 26c, 26c of the roller shaft 26a protruding from the end side surfaces of the roller 26b, respectively (see
On the bottom surface of the recessed portion 61, guide walls 63 which extend toward the photoconductive drum 21 are provided. The guide walls 63 guide the supporting members 60 in a direction from the bottom surface of the recessed portion 61 toward the photoconductive drum 21, which is in the urging direction of the springs 62. As shown in
As shown in
The laser printer 1 employs a so-called cleaner-less toner collection method. That is, the residual toner that remains on the circumferential surface of the photoconductive drum 21 after the toner image has been transferred to the recording sheet 3 is collected using the developing roller 22. Since the cleaner-less method is employed, it is not necessary to provide a cleaning device such as a cleaning blade and a waste toner tank for collecting the waste toner to the printer 1. Therefore, according to the first embodiment, the configuration of the laser printer can be simplified, and the size and manufacturing cost can be decreased.
According to the first embodiment, on both walls that face each other at the passage 2b, a guide grooves 2d, 2d are formed. In
The roller shaft 21a of the photoconductive drum 21 is supported by the side walls 20a, 20a of the drum cartridge 20. The lower end of each side wall 20a is configured as follows (see
As described above, the end portions 26c and 26c of the roller shaft 26a of the transfer roller 26 is rotatably supported by the supporting members 60, 60, which are urged upward by the springs 62. When the process cartridge 12 is being attached or being detached, the lower end portion of each side wall 20a of the process cartridge 12 contacts the upper end surface of corresponding supporting member 50. The front and rear side ends of the upper surface are formed to be curved tapered surfaces 60a, 60a (see
As shown in
When the process cartridge 12 is further inserted rearward, as shown in
Further, in this state, the upper end portions of the supporting members 60 do not contact the dent portions 67 of the side walls 20a. With this configuration, the pressing force of the process cartridge (due to the sliding movement along the guide grooves 2d) and the urging force of the springs 62 increase the pressing force between the photoconductive drum 21 and the transfer roller 26, which provides the nip therebetween in a stable state.
Because of the tapered surface 65a of the first extended portion 65 of each side wall 20a and the tapered surface 60a of the rear end side of each supporting member 60, the upper portion of the supporting member 60 is moved into the dent portion 67 gradually as the processing cartridge 12 is inserted. Further, the position in the front and rear direction of the upper portion of each supporting member 60 is adjusted as it is sandwiched between the first extended portion 65 and the second extended portion 66.
When the process cartridge 12 is detached, due to the contact between the upper portion of the supporting members 60 and the first extended portions 65 of the side walls 20a (see
According to the first embodiment described above, when the process cartridge 12 is fully inserted in the main body 1a, the photoconductive drum 21 and the transfer roller 26 are press-contacted with each other. When the process cartridge 12 is not in the mount complete state, by the pressing force applied by the process cartridge 12, the photoconductive drum 21 and the transfer roller 26 are separated. Therefore, only by the detaching/attaching operation of the process cartridge 12, the contact/separated states between the photoconductive drum 21 and the transfer roller 26 are appropriately set. Thus, the first embodiment enables the user to detach/attach the process cartridge with a simple operation. Further, the first embodiment also provides a simple configuration.
In the mount completed state, the upper end of each supporting member 60 does not contact the dent portion of the corresponding side wall 20a. Thus, the pressing force generated by the process cartridge and urging force of the spring 62 applied to the supporting member 60 are effectively used for the press-contact between the photoconductive drum 21 and the transfer roller 26, and the nip therebetween is provided in a stable state.
Further, when in a non-mounted state (i.e., when the process cartridge 12 is not set to the mount completed position), the pressing force provided by the process cartridge 12 moves the supporting members 60 against the urging force of the springs 62, thereby the photoconductive roller 21 and the transfer roller 26 are separated from each other and the nipped state is released. With such a configuration, a locus of the process cartridge 12 in a direction where the photoconductive drum 21 and the transfer roller 26 are separated is unnecessary since the supporting members 60 are movable. Thus, the configuration according to the first embodiment contributes to downsizing of the laser printer 1.
Furthermore, only by attaching/detaching the process cartridge 12 with respect to the main body 1a, the engagement of the connection gear 21b with the gear 26d can be made/released at the same time, which is very convenient. Therefore, the operability of the laser printer 1 is improved.
In the mount completed state, the upper end portions of the supporting members 60 are appropriately positioned in the front and rear direction as they are sandwiched between the first extended portions 65 and the second extended portions 66, respectively. Therefore, the photoconductive drum 21 and the transfer roller 26 are faces and are press-contacted with each other in an appropriate manner.
As shown in
During a process of attaching the process cartridge 12 to the main body 1a, due to the engagement between the tapered surface 65a at the rear end of the first extended portion 65 of each side wall 20a and the tapered surface 60a of the front end of each supporting member 60, the upper portion of the supporting members 60 gradually fit in the dent portions 67. Accordingly, the photoconductive drum 21 is gradually pressed to the transfer roller 26. Further, with this configuration, the attaching operation can be done smoothly.
As shown in
According to the second embodiment, as shown in
As shown in
When the process cartridge 12 is inserted in the attaching portion, the openable/closable door 70 is opened. When the process cartridge 12 is inserted, as shown in
When the process cartridge 12 is inserted to a position as shown in
As described above, the second embodiment is configured such that the process cartridge 12 is rotated about the rear end side portion (e.g., the roller shaft 21a of the photoconductive drum 21), and the process cartridge 12 is set to the mount completed state with respect to the attaching section 2c. When the process cartridge 12 is not in the mount completed state, the protruded portions 71 contact the upper surfaces of the supporting members 60, thereby the photoconductive drum 21 and the transfer roller 26 are separated. When the process cartridge 12 is set to the mount completed state, the photoconductive drum 21 and the transfer roller 26 are press-contacted. Therefore, only by the attaching/detaching operations of the process cartridge 12, the photoconductive drum 21 and the transfer roller 26 are press-contacted/separated. According to the second embodiment, with a relative simple structure, the attaching/detaching operations of the process cartridge can be done with protecting the photoconductive drum 21.
As shown in
It should be noted that the present invention need not be limited to the above described illustrative embodiments, and various modification as indicated below are also included in the scope of the invention.
In the above-described embodiments, the transfer roller 26 is urged toward the photoconductive roller with the urging force of the springs 62. It should be noted that the transfer roller 26 may be configured to be located at a fixed position and the photoconductive drum 21 is moveable depending on the position of the process cartridge 12. Alternatively, it may be possible that the transfer roller and/or the photoconductive drum is simply moved between a contacted position and a separated position depending on whether the process cartridge has been completely attached or it is being attached/detached without employing an urging member.
In the above-described embodiments, the dent portion is formed on the process cartridge, while the protruded portion is provided to the main body 1a. It is possible to provide the dent portion to the main body 1a and the protruded portion on the process cartridge.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-162430 | May 2004 | JP | national |
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|---|---|---|---|
| 5486898 | Fujii et al. | Jan 1996 | A |
| 5572305 | Hayashi et al. | Nov 1996 | A |
| 5867751 | Nomura et al. | Feb 1999 | A |
| 5923935 | Yamaguchi | Jul 1999 | A |
| 6084622 | Sugiura et al. | Jul 2000 | A |
| 6714750 | Terada et al. | Mar 2004 | B2 |
| Number | Date | Country |
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| 05-216356 | Aug 1993 | JP |
| 07-152303 | Jun 1995 | JP |
| 07-191557 | Jul 1995 | JP |
| 07-302007 | Nov 1995 | JP |
| 11-052814 | Feb 1999 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20050265747 A1 | Dec 2005 | US |
