Patent Grant
8472837
The present invention relates to a color electrophotographic image forming apparatus in which a plurality of cartridges is detachably mountable to an apparatus main assembly and a color image is formed on a recording material (medium).
The color electrophotographic image forming apparatus forms the color image on the recording material by using an electrophotographic image forming process. Examples of the color electrophotographic image forming apparatus may include a color electrophotographic copying machine, a color electrophotographic printer (such as a color laser beam printer or a color LED printer), a color facsimile machine, a color word processor, and the like. Further, the recording material is a medium on which the image is to be formed by the electrophotographic image forming apparatus and, e.g., includes paper, an OHP sheet, and the like.
Further, the cartridge may, e.g., include a process cartridge or a developing cartridge. The cartridge is provided detachably mountable to the apparatus main assembly of the electrophotographic image forming apparatus. The cartridge contributes to an image forming process, for forming the image on the recording material, in a state in which the cartridge is mounted in the apparatus main assembly. The process cartridge is prepared by integrally assembling process means and an electrophotographic photosensitive drum (hereinafter referred to as a photosensitive member) into a cartridge. The process means act on the photosensitive member. For example, the process cartridge is prepared by integrally assembling the photosensitive member (the electrophotographic photosensitive drum) and, as the process means, at least one of a charging means, a developing means, and a cleaning means into a cartridge and is detachably mountable to the apparatus main assembly. The process cartridge integrally including the mount and the developing means is referred to as that of a so-called integral type. Further, the process cartridge integrally including the photosensitive member and the process means other than the developing means is referred to as that of a so-called separation type. That is, the separation type process cartridge is used as a drum cartridge for forming an image by being paired with a developing unit (developing cartridge) prepared separately from the process cartridge by including the developing means. The process cartridge can be mounted in and demounted from the apparatus main assembly by a user himself (herself). For that reason, maintenance of the apparatus main assembly can be performed easily.
The developing cartridge includes a developing roller and a developer (toner) used for developing an electrostatic latent image formed on the photosensitive member by the developing roller and is detachably mounted in the apparatus main assembly. In the case of the developing cartridge, the photosensitive member is mounted in the apparatus main assembly or on a cartridge supporting member. Alternatively, the photosensitive member is provided in the so-called separation type process cartridge (drum cartridge). In this case, as described above, the process cartridge does not include the developing means. The developing cartridge can also be mounted and demounted from the apparatus main assembly by the user alone. For that reason, the maintenance of the apparatus main assembly can be performed easily.
In the present invention, the cartridge includes the above-described so-called integral type and separation type process cartridges. Further, the cartridge includes a pair of the so-called separation type process cartridge and the developing cartridge which are used in combination. Further, the cartridge also includes the case where the photosensitive member is mounted in the apparatus main assembly or on the cartridge supporting member and the developing cartridge is used openably and detachably mountable with respect to the photosensitive member.
U.S. Pat. No. 5,428,426 discloses an image forming apparatus capable of forming a color image. The image forming apparatus has a constitution in which an intermediary transfer member is driven by an apparatus main assembly-side driving source and a photosensitive drum is rotationally driven via the intermediary transfer member.
U.S. Pat. No. 6,647,227 discloses an image forming apparatus having a constitution in which a process means accommodating member in which a plurality of developing cartridges and a photosensitive belt mechanism portion are detachably mounted can be pulled out from an intermediary transfer member accommodating member.
The present invention has further developed the above-described conventional constitutions.
A principal object of the present invention is to provide a color electrophotographic image forming apparatus which enables easy mounting and demounting of a mount cartridge and which is easy to use by a user.
According to an aspect of the present invention, there is provided a color electrophotographic image forming apparatus comprising:
a photosensitive member cartridge, detachably mountable to a main assembly of the color electrophotographic image forming apparatus, for holding a photosensitive member;
a plurality of developing cartridges each including a developing roller for developing an electrostatic latent image formed on the photosensitive member into a developer image, the plurality of developing cartridges being demountable from the photosensitive member cartridge;
a main assembly-side guide portion, provided in the main assembly, for guiding the photosensitive member cartridge demountably from the main assembly;
a photosensitive member cartridge-side guide portion, provided in the photosensitive member cartridge, for guiding the plurality of developing devices independently demountably from the photosensitive member cartridge;
a preventing portion, provided in the photosensitive member cartridge, for preventing movement of the photosensitive member cartridge,
wherein when an operation for demounting the developing cartridge is performed in a state in which the photosensitive member cartridge is mounted in the main assembly, the preventing portion is movable between a first position in which the photosensitive member cartridge is prevented from moving in a demounting direction in which the photosensitive member cartridge is to be demounted and a second position in which the photosensitive member cartridge is permitted to move in the demounting direction; and
a grip portion for permitting demounting of the photosensitive member cartridge, the grip portion being operable so as to change a position of the preventing portion from the first position to the second position.
According to another aspect of the present invention, there is provided a color electrophotographic image forming apparatus comprising:
a photosensitive member cartridge, detachably mountable to a main assembly of the color electrophotographic image forming apparatus, for holding a photosensitive member;
a plurality of developing cartridges each including a developing roller for developing an electrostatic latent image formed on the photosensitive member into a developer image, the plurality of developing cartridges being demountable from the photosensitive member cartridge;
wherein the developing roller included in each of the plurality of portions opposes a circumferential surface of the photosensitive member having a curvature;
a main assembly-side guide portion, provided in the main assembly, for guiding the photosensitive member cartridge demountably from the main assembly;
a photosensitive member cartridge-side guide portion, provided in the photosensitive member cartridge, for guiding the plurality of developing devices independently demountably from the photosensitive member cartridge;
a demounting portion, provided as a part of the photosensitive member cartridge, being movable between a fifth position in which demounting of the photosensitive member from the photosensitive member cartridge is permitted and a sixth position in which the demounting of the photosensitive member from the photosensitive member cartridge is prevented,
wherein the photosensitive member is movable in an axial direction thereof or in a direction in which the photosensitive member is moved away from the developing cartridges.
According to another aspect of the present invention, there is provided a photosensitive member cartridge, detachably mountable to a main assembly of a color electrophotographic image forming apparatus, for holding a photosensitive member, the photosensitive member cartridge comprising:
a portion to be guided by a main assembly-side guide portion, provided in the main assembly, for guiding the photosensitive member cartridge;
a photosensitive member cartridge-side guide portion for guiding a plurality of developing cartridges each including a developing roller for developing an electrostatic latent image formed on the photosensitive member into a developer image, independently demountably from the photosensitive member cartridge;
a preventing portion for preventing movement of the photosensitive member cartridge,
wherein when an operation for demounting the developing cartridge is performed in a state in which the photosensitive member cartridge is mounted in the main assembly, the preventing portion is movable between a first position in which the photosensitive member cartridge is prevented from moving in a demounting direction in which the photosensitive member cartridge is to be demounted and a second position in which the photosensitive member cartridge is permitted to move in the demounting direction; and
a grip portion for permitting demounting of the photosensitive member cartridge, the grip portion being operable so as to change a position of the preventing portion from the first position to the second position.
According to a further aspect of the present invention, there is provided a photosensitive member cartridge, detachably mountable to a main assembly of a color electrophotographic image forming apparatus, for holding a photosensitive member, the photosensitive member cartridge comprising:
a portion to be guided by a main assembly-side guide portion, provided in the main assembly, for guiding the photosensitive member cartridge;
a photosensitive member cartridge-side guide portion for guiding a plurality of developing cartridges each including a developing roller for developing an electrostatic latent image formed on the photosensitive member into a developer image, independently demountably from the photosensitive member cartridge,
wherein the developing roller included in each of the plurality of developing cartridges opposes a circumferential surface of the photosensitive member having curvature;
a demounting portion being movable between a fifth position in which demounting of the photosensitive member from the photosensitive member cartridge is permitted and a sixth position in which the demounting of the photosensitive member from the photosensitive member cartridge is prevented,
wherein the photosensitive member is movable in an axial direction thereof or in a direction in which the photosensitive member is moved away from the developing cartridges.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
a) is a perspective view of an outer appearance of a photosensitive member cartridge, and
a) is a perspective view of a principal part of a locking mechanism for the photosensitive member cartridge,
a) is a perspective view of an outer appearance of the image forming apparatus in a state in which a door is opened, and
a) is a perspective view of an outer appearance of the image forming apparatus in a state in which the photosensitive member cartridge is mounted in the apparatus main assembly and only one of the developing cartridges is demounted from or mounted into the apparatus main assembly, and
a) is a perspective view of an outer appearance of the image forming apparatus in a state in which the photosensitive member cartridge is demounted as seen from a right side surface side,
a) is a left side surface view of the photosensitive member cartridge in a mounting state, and
a) is a schematic view for illustrating a structure of a photosensitive member cartridge in Embodiment 2, and
[Embodiment 1]
(General Structure of a Color Electrophotographic Image Forming Apparatus)
At a cartridge mounting portion 1C located at a central portion in the image forming apparatus 1, the cartridge 3 including a drum-shaped photosensitive member (hereinafter referred to as a drum) 2 is mounted demountably from the apparatus main assembly 1A as described later. The drum 2 is rotationally driven, at a predetermined speed in a counterclockwise direction indicated by an arrow, by a driving mechanism (not shown). Further, at a developing cartridge mounting portion of the cartridge 3, a plurality of developing cartridges 4 each including the developing roller 20 is mounted demountably from the cartridge 3 as described later. In this embodiment, the plurality of developing cartridges 4 is first to fourth (four) cartridges 4y, 4m, 4c and 4k which are vertically disposed at four stages on the front side of the drum 2. Yellow (y) toner is accommodated as a developer in a developer accommodating portion 42y of the first cartridge 4y, and magenta (m) toner is accommodated in a developer accommodating portion 42m of the second cartridge 4m. Further, cyan (c) toner is accommodated in a developer accommodating portion 42c of the third cartridge 4c, and black (k) toner is accommodated in a developer accommodating portion 42k of the fourth cartridge 4k. The cartridge 3 and the developing cartridges 4 will be described more specifically later.
On an upper side of the cartridge 3, a belt unit 5 is disposed. The unit 5 includes a driving roller 51 disposed on a rear side in the apparatus main assembly 1A and a tension roller 52 disposed on a side on which the tension roller 52 is located closer to the front side than the driving roller 51. The unit 5 further includes an endless intermediary transfer belt 53 which is extended and stretched around the two rollers 51 and 52 and is formed of a dielectric material and which has flexibility. Inside the belt 53, a primary transfer roller 6 is disposed. The roller 6 contacts and urges a lower side belt portion of the belt 53 toward the drum 2 with a predetermined urging force. A contact portion between the belt 53 and the drum 2 is a primary transfer nip T1. The belt 53 is circulated and moved in the same direction as the rotational direction of the drum 2 at a speed corresponding to the speed of the drum 2 by driving the roller 51 by a driving mechanism (not shown). At a portion where the belt 53 contacts and is extended around the roller 51, a secondary transfer roller 10 is disposed. The roller 10 is positionally moved, between an operating position in which the roller 10 contacts the belt 53 toward the roller 51 and is indicated by a solid line and a non-operating position in which the roller 10 is separated from the belt 53 and is indicated by a broken line, by a shifting mechanism (not shown). The roller 10 is normally held at the non-operating position and is moved to the operating position with predetermined control timing. In a state in which the roller 10 is moved to the operating position, the cartridge position between the roller 10 and the belt 53 is a secondary transfer nip T2. At a lower portion of the inside of the apparatus main assembly 1Am a sheet feeding unit 28 is disposed. The unit 28 includes a cassette 7 in which a sheet-like recording material S is stacked and accommodated, and includes a pick-up roller 8. The cassette 7 is freely mounted into and demounted from the apparatus main assembly 1 from the front side (front loading). The cassette 7 is provided with a grip 7a at its front surface. In the apparatus main assembly 1A, between the cartridge 3 and a rear surface of the apparatus main assembly 1A, a recording material conveying path Z extending from the roller 8 to an upper rear portion in the apparatus main assembly A is provided. Along the conveying path Z, from the lower portion to the upper portion, a conveying roller pair (registration roller pair) 9, the secondary transfer roller 10, a fixing device 12 and a discharge roller pair 13 are disposed. At an upper surface of the apparatus main assembly 1A, a sheet discharge tray 29 on which an image-formed recording material S is to be discharged is disposed.
An operation for forming a full-color image is as follows. On the basis of an image formation start signal, the drum 2 and the belt 53 are rotationally driven. A laser scanner (optical scanner) 15 is also driven. The secondary transfer roller 10 is held at the non-operating position. A predetermined charging bias is applied to a charging roller 11, so that the surface of the drum 2 is uniformly charged to a predetermined polarity and a predetermined potential (charging step). From the scanner 15, laser light L modulated correspondingly to a y-color component image signal for the full-color image is emitted (output), so that the uniformly charged surface of the drum 2 is subjected to scanning exposure (exposure step). As a result, an electrostatic latent image corresponding to the y-color component image is formed on the drum surface. The first developing cartridge 4y performs a developing operation with predetermined control timing. That is, the developing roller 20 of the cartridge 4y is rotationally driven and a predetermined developing bias is applied to the developing roller 20. As a result, the electrostatic latent image on the drum surface is developed as a y-color toner image (developing step). Then, the y-color toner image is primary-transferred from the surface of the drum 2 onto the belt 53 in the nip T1. To the roller 6, with predetermined control timing, a primary transfer bias of a predetermined potential and of an opposite polarity to a toner charge polarity is applied. The drum surface after the primary transfer is cleaned by a drum cleaner 27 as a cleaning member such as a blade. When the primary transfer of the y-color toner image onto the belt 53 is completed, a step of forming an m-color toner image corresponding to an m-color component image for the full-color image is performed. In this case, the drum 2 is exposed to the laser light L modulated correspondingly to the m-color component image signal and the second cartridge 4m performs the developing operation. Then, the m-color toner image is superposedly primary-transferred from the drum 2 onto the belt 53 in a state in which the m-color toner image is positionally aligned with the y-color toner image which has already been transferred onto the belt 53. When the primary transfer of the m-color toner image onto the belt 53 is completed, a step of forming a c-color toner image corresponding to a c-color component image is performed. In this case, the drum 2 is exposed to the laser light L modulated correspondingly to the c-color component image signal and the third cartridge 4c performs the developing operation. Then, the c-color toner image is superposedly primary-transferred from the drum 2 onto the belt 53 in a state in which the c-color toner image is positionally aligned with the y-color toner image and the m-color toner image which have already been transferred onto the belt 53. When the primary transfer of the c-color toner image onto the belt 53 is completed, a step of forming a k-color toner image corresponding to a k-color component image is performed. In this case, the drum 2 is exposed to the laser light L modulated correspondingly to the k-color component image signal and the fourth cartridge 4k performs the developing operation. Then, the k-color toner image is superposedly primary-transferred from the drum 2 onto the belt 53 in a state in which the k-color toner image is positionally aligned with the y-color toner image, the m-color toner image and the c-color toner image which have already been transferred onto the belt 53.
Thus, on the belt 53, an unfixed full-color toner image based on the toner images of the four colors (y, m, c and k) is synthetically formed. Incidentally, the order of the colors of the toner images successively formed on the drum 2 is not limited to the order of y, m, c and k in this embodiment but may also be appropriately changed. Before a leading end portion of the unfixed (four color-based) full-color toner image transferred on the belt 53 reaches the position of the roller 10 by the movement of the belt 53, the roller 10 is moved to the operating position in which the roller 10 contacts the belt 53. On the other hand, the roller 8 is driven with predetermined control timing. As a result, the recording material S in the cassette 7 is fed one by one. The fed recording material S is introduced into the nip T2 with predetermined control timing by the conveying roller pair 9. To the roller 10, the secondary transfer bias of the predetermined potential and of the opposite polarity to the toner charge polarity is applied. As a result, in a process in which the recording material S is nip-conveyed in the nip T2, the four color toner images superposed on the belt 53 are collectively secondary-transferred onto the surface of the recording material S. The recording material S is separated from the surface of the belt 53 and introduced into the fixing device 12, thus being subjected to application of heat and pressure in a fixing nip. As a result, the respective color toner images are fixed on the recording material S. Then, the recording material S comes out of the fixing device 12 and is discharged on the discharge tray 29 by the discharge roller pair 13 as a full-color image-formed product.
(Photosensitive Member Cartridge)
a) is a perspective view of an outer appearance of the cartridge 3 as seen from the left side surface side, and
Each of the locking claws 61L and 61R is rotationally urged about the shaft 60, in the counterclockwise direction indicated by a double-pointed arrow in
(Developing Cartridge)
b) is a perspective view of an outer appearance of the developing cartridge 4 as seen from the left side surface side, and
(Cartridge Exchange Method)
In an individual developing cartridge 4, with the use for image formation, the toner accommodated in the toner frame 42 is gradually consumed. Then, when the developer (toner) is consumed to such an extent that an image having a satisfactory quality for a user cannot be formed, the developing cartridge 4 loses its commercial value. For this reason, e.g., a means (not shown) for detecting a remaining developer amount of the individual developing cartridge 4 is provided. Then, in a control circuit portion (not shown), the remaining developer amount detected by the means is compared with a threshold preset for advance notice or warning of the end of a lifetime of the developing cartridge 4. With respect to the developing cartridge 4 for which the detected remaining developer amount is less than the threshold, the lifetime-end advance notice or warning is displayed at a display portion of an operating portion (not shown). As a result, the user is urged to prepare a developing cartridge for the exchange or to exchange the developing cartridge 4, so that an output image quality is maintained. Further, also with respect to the photosensitive member cartridge 3, when the integrated number of sheets subjected to the image formation exceeds a predetermined value, the satisfactory quality image for the user is gradually unable to be formed due to a lifetime end of the drum 2 or full of a residual toner containing portion. For this reason, the control circuit portion determines the integrated number of sheets by, e.g., counting the number of rotation of the drum 2 with respect to the mounted cartridge 3 and compares the count with a threshold preset for advance notice or warning of the lifetime end of the cartridge 3. Then, when the integrated number is close to the threshold, the lifetime-end advance notice or warming of the cartridge 3 is displayed at the display portion of the operating portion. As a result, the user is urged to prepare a photosensitive member cartridge for exchange or to exchange the cartridge 3, so that the output image quality is maintained.
In the image forming apparatus in this embodiment, the exchange of the developing cartridge 4 and the cartridge 3 is performed in a front access manner in order to improve usability. That is, on the front surface side of the apparatus main assembly 1A, an opening 1B is provided. The opening 1B permits passing of the developing cartridge 4 and the cartridge 3 in order that the developing cartridge 4 and the cartridge 3 can be mounted into and demounted from the apparatus main assembly 1A. Further, a door (openable member) 14 movable between a closed position in which the opening 1B is covered and an open position in which the opening 1B is uncovered. In this embodiment, the door 14 is rotationally movable about a horizontal shaft (hinge shaft) 14b, provided on a lower side of the door 14, so as to cover and uncover the inside of the apparatus main assembly 1A. That is, the door 14 can be rotationally moved about the horizontal shaft 14b in a rising direction to be placed in a closed state in which the door 14 covers the inside of the apparatus main assembly 1A as shown in
In the apparatus main assembly 1A, above the cassette 7, an intermediate bottom plate 1D is provided substantially horizontally. Further, as shown in
The mounting of the cartridge 3 into the apparatus main assembly 1A will be described with reference to
Next, the case where the cartridge 3 mounted in the apparatus main assembly 1A is demounted will be described. The door 14 is opened to uncover the opening 1B. The grip 23 of the cartridge 3 is rotationally moved downwardly against the urging force of the urging spring 62. As a result, the locking of the cartridge 3 in the apparatus main assembly 1A is released, so that the cartridge 3 can be moved in the forward direction in the apparatus main assembly 14. In the lock-released state, the cartridge 3 is moved and pulled out of the apparatus main assembly 1A. the pulling-out movement of the cartridge 3 is guided groove portions 16A. The outwardly projected portions of the bearings 18L and 18R pass under the downward angled portions 81a of the members 81 to be escaped forward from the recessed portions 80. Then, the cartridge 3 insufficiently moved in the forward direction to be pulled out of the apparatus main assembly 1A. That is, the cartridge 3 is constituted so as to be demountable from the apparatus main assembly 1A together with the developing cartridge 4 in the state in which the developing cartridges 4y, 4m, 4c and 4k are detachably mounted in the cartridge 3.
The mounting and demounting of each developing cartridge 4 from the mounting portion 35 of the cartridge 3 can be performed, as shown in
The demounting of the developing cartridge 4 mounted in the cartridge 3 is performed by gripping grips 46, with fingers, provided at left and right portions of the developing cartridge 4 on the front surface side and then by pulling and moving the developing cartridge 4 in the forward direction along the left and right guide portions 36 against the urging force of the springs 22. As a result, the developing cartridge 4 can be mounted from the mounting portion 35 of the cartridge 3 to the outside of the cartridge 3. When only the developing cartridge 4 is pulled out and demounted from the mounting portion 35 in the state in which the cartridge 3 is mounted in the apparatus main assembly 1A, the cartridge 3 is locked in the apparatus main assembly 1A by the locking mechanism 63 to be prevented from moving in the forward direction. For this reason, the cartridge 3 is not pulled out together with the developing cartridge 4. That is, from the cartridge 3 mounted in the apparatus main assembly 1A, the plurality of the developing cartridge 4 can be independently demounted. Further, on the other hand, into the cartridge 3 mounted in the apparatus main assembly 1A, the developing cartridges 4 can be independently mounted.
Outside the cartridge 3, as shown in
That is, when the locking claws 61 are located at the lock-released position (second position), the stopper members 64 are located at the preventing position (third position). Further, when the locking claws 61 are located at the preventing position (first position), the stopper members 64 are located at the stand-by position (fourth position).
In the case where the cartridge 3 is moved swiftly when the cartridge 3 is mounted or demounted, there is a possibility that the developing cartridges 4 come out of the cartridge 3 by the swift movement. However, in the constitution in this embodiment, it is possible to prevent the developing cartridges 4 from coming out of the cartridge 3 by the stopper members 64.
As described above, relative to the cartridge 3, the drums 2 and the developing rollers 20 are positioned by the same part 30. Further, as described in this embodiment, the four developing cartridges 4y, 4m, 4c and 4k are positioned. As a result, a complicated exchange operation such that the cartridge 3 is demounted after the four developing cartridges 4 are demounted when the cartridge 3 is exchanged can be avoided, so that alignment of the cartridge 3 with the four developing cartridges 4 can be ensured.
Incidentally, in Embodiment 1, the cylindrical drum is described as the photosensitive member. However, the present invention is not limited thereto but may also employ a photosensitive belt.
[Embodiment 2]
An image forming apparatus in this embodiment will be described with reference to
Further, a demounting constitution of the drum 2 which is a feature of this embodiment will be described. The photosensitive member has the drum shape and each developing cartridge 4 is disposed to oppose the circumferential surface of the drum 2 having curvature (
a) and 10(b) show a constitution of the demounting of the drum 2. The cartridge 3 is constituted by two portions consisting of a drum holding portion (demounting portion) 3F and a developing cartridge holding portion 3R.
By releasing engagement between the drum locking claw 96 and the boss 100, the drum holding portion 3F can be exposed and rotationally moved about the boss 100 to the drum demounting position as shown in
Further, as shown in
Incidentally, in the constitution shown in
While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.
This application claims priority from Japanese Patent Applications Nos. 177667/2009 filed Jul. 30, 2009 and 147533/2010 filed Jun. 29, 2010, which is hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-177667 | Jul 2009 | JP | national |
| 2010-147533 | Jun 2010 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20110026968 A1 | Feb 2011 | US |
