JP5760354B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus. More specifically, the present invention relates to an image forming apparatus having a detachable drum unit.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has a photoreceptor, and the surface is charged and exposed to form an electrostatic latent image. Further, toner is supplied to the formed electrostatic latent image by a developing device to form a toner image. In general, the photosensitive member, the charging device, and the developing device have a short lifetime compared with other parts of the image forming apparatus, and are thus attached in a replaceable manner. For example, these are integrated into a detachable body and commercialized as an imaging unit. On the other hand, the exposure apparatus has a long life and is not exchanged for normal use.

  The exposure apparatus is an apparatus that forms an electrostatic latent image by irradiating light to a photoconductor. For this reason, it is disposed in the vicinity of the photosensitive member and its irradiation area is open. If there is a foreign object on the optical path between the exposure device and the photoconductor, the image quality may be deteriorated. In particular, when the imaging unit is replaced, foreign matter such as dust accumulated inside is likely to fly, and it is not preferable that this adheres to the irradiation surface of the exposure apparatus. On the other hand, for example, Patent Document 1 discloses an image forming apparatus in which a dustproof glass and a reflection mirror of an exposure apparatus are cleaned when an imaging unit is attached or detached.

JP-A-7-129060

  In recent years, it has become possible to make the life of the developing device considerably longer than the life of the photoreceptor, and it has become desirable not to replace them at the same time. That is, instead of replacing the imaging unit, it is only necessary to replace the drum unit including the photosensitive member and the charging device while leaving the developing device. However, when only the drum unit is replaced, there is a problem that the configuration for preventing toner scattering provided between the photosensitive member and the developing device does not function during the replacement operation.

  For example, there is a type in which a seal is provided between the photosensitive member and the developing device to prevent smoke from toner. If the developing device and the photosensitive member are separated from each other, not only the sealing by the seal cannot be performed but also the toner collected by the seal may be scattered in the device. It is not preferable that the toner scatters and adheres to the irradiation surface of the exposure apparatus. A method of separating the developing device from the photosensitive member after taking it out as an imaging unit is also conceivable, but it is not preferable because the operation becomes complicated.

  The present invention has been made to solve the problems of the conventional image forming apparatus described above. That is, an object of the present invention is to provide an image forming apparatus in which only a drum unit can be replaced while leaving a developing device in the apparatus while preventing foreign matter from adhering to an irradiation surface of an exposure apparatus.

  The image forming apparatus of the present invention, which has been made for the purpose of solving this problem, irradiates light from the irradiation surface to the photosensitive member, a charging unit that uniformly charges the surface of the photosensitive member, and the surface of the charged photosensitive member. An image forming apparatus having an exposure unit that forms an electrostatic latent image and a developing unit that supplies toner to the formed electrostatic latent image to form a toner image, and is detachable from the image forming apparatus A drum unit that includes a photosensitive member and a charging unit and does not include an exposure unit and a developing unit, and a developing position and a photosensitive member that are configured to develop an electrostatic latent image formed on the photosensitive member. The developing unit moving unit that moves between a remote position and a distance between the developing unit moving unit, and the movement of the developing unit by the developing unit moving unit moves between the shielding position that covers the irradiation surface of the exposure unit and the unexposed exposure position. However, when the developing unit is at the developing position, it becomes an exposed position. When in the separation position are those having a shutter serving as a shielding position.

  According to the image forming apparatus of the present invention, since the developing unit moving unit is provided, the developing unit is moved between the developing position and the separation position. When exchanging the drum unit, the developing unit is set at the separation position, so that only the drum unit can be taken out while leaving the developing unit in the apparatus. In addition, the shutter moves in conjunction with the movement of the developing unit, and when the developing unit is in the separated position, the irradiation surface of the exposure unit is shielded, so that foreign substances that move with the replacement of the drum unit adhere to the irradiation surface. Is prevented.

Further , according to one aspect of the present invention, in the above configuration, the shutter moves from the exposure position to the shielding position before the development unit moves from the development position to the separation position, and the development unit moves from the separation position to the development position. when moving to the Ru der intended to move from then covering position to the exposed position.
If the developing unit is separated, there is a possibility that foreign matter will fly between the developing unit and the photosensitive member. The Rukoto look like this, while the developing unit is separated from the slightest photoreceptor, since always shield the irradiated surface, it can be reliably prevented from adhering foreign matter into the irradiation surface.

Further, in another aspect of the present invention, in the structure of [0008], the shutter, when in the Exposure position, guided for movement along the exposed portion by attaching a cleaning tool for cleaning the exposed portion A guiding shape is formed.
In this way, the exposure part can be easily cleaned.

Furthermore, in any of the above aspects, it is desirable that the developing unit moving unit has a cam unit that is moved by an operator's operation to push and move the developing unit . The image forming apparatus of this embodiment, it is desirable to have a link for moving the shutter is pushed together with the developing unit by the cam portion.
If so, the shutter is moved with the movement of the developing unit. Therefore, the foreign matter is reliably prevented from adhering to the irradiated surface.

Also, in yet another aspect of the present invention, in the structure of [0008], the shutter is that is fixed to the developing unit moving unit.
The Rukoto looks like this, Ru can appropriately move the shutter.

Further , in any aspect of the present invention , it is desirable that the exposure portion is disposed below the development portion of the photosensitive member by the developing portion, and the shutter has a box shape with the upper portion opened. If it has become like this, it can receive and accumulate a foreign substance in the box-shaped inside.

  According to the image forming apparatus of the present invention, it is possible to replace only the drum unit while leaving the developing device in the apparatus while preventing foreign matter from adhering to the irradiation surface of the exposure apparatus.

1 is a schematic configuration diagram illustrating a color printer according to an embodiment. It is a schematic block diagram which shows the image formation part of a 1st form. It is a schematic block diagram which shows the image formation part of a 1st form. It is a schematic block diagram which shows the image formation part of a 2nd form. It is a schematic block diagram which shows the image formation part of a 2nd form. It is a schematic block diagram which shows the image formation part of a 2nd form. It is a perspective view which shows another example of a shutter. It is explanatory drawing which shows the example of arrangement | positioning which cleans an irradiation surface. It is a perspective view which shows the example of a cleaning brush. It is a perspective view which shows another example of a cam.

"First form"
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a so-called tandem image forming apparatus.

  The color printer 1 of the present embodiment is a so-called tandem image forming apparatus capable of forming a color image, as shown in FIG. In the middle of the figure, four color image forming portions are arranged along the intermediate transfer belt 11 in the order of yellow 10Y, magenta 10M, cyan 10C, and black 10K from left to right in the figure. In addition, a detachable paper feed cassette 13 is attached to the lower left portion of the color printer 1 in the drawing, and a manual feed unit 14 is attached to the lower right portion of the drawing.

  As shown in FIG. 1, the yellow image forming unit 10 </ b> Y includes a charging unit 22, a developing unit 24, a primary transfer unit 25, and a cleaner 26 with a photosensitive member 21 at the center. In the drawing, only the yellow image forming unit 10Y is described with reference numerals, but the other colors have the same configuration. The exposure unit 23 is provided below the image forming unit for each color, and is common to each color. Furthermore, hoppers 28Y, 28M, 28C, and 28K that store toner of each color are provided above the intermediate transfer belt 11 in the drawing.

  Further, on the right side in FIG. 1, paper transport paths 31 and 32 are provided. In the drawing, a sheet conveyance path 31 for conveying a sheet from bottom to top and a sheet conveyance path 32 for conveying a sheet from top to bottom in the figure are provided side by side. The paper transport path 32 is used when performing duplex printing. A plurality of conveyance rollers 33 are provided in the sheet conveyance paths 31 and 32, respectively. The color printer 1 according to the present embodiment is capable of conveying or stopping a sheet along the conveyance paths 31 and 32 as needed by controlling these conveyance rollers 33.

  As shown in FIG. 1, a secondary transfer unit 35 and a fixing unit 36 are arranged in the paper transport path 31. The fixing unit 36 includes a roller pair formed by two rollers (a heating roller 37 and a pressure roller 38) facing each other. The secondary transfer unit 35 has a secondary transfer roller 41. The secondary transfer roller 41 faces the belt roller 42 with the intermediate transfer belt 11 interposed therebetween. Furthermore, the color printer 1 of this embodiment has a control unit 40 for controlling each unit.

  Next, the operation of each unit when a color image is formed by the color printer 1 will be described. A toner image is formed on each color photoconductor 21 at the same timing. That is, it is uniformly charged by the charging unit 22 and subsequently exposed by the exposure unit 23. As a result, an electrostatic latent image based on the image data of each color is formed on the surface of the photoconductor 21 of each color. Next, the developing unit 24 supplies toner to the electrostatic latent image, and a toner image is formed on the photoreceptor 21.

  On the other hand, at the time of image formation, the intermediate transfer belt 11 is rotated counterclockwise as shown by an arrow g in FIG. The toner images respectively formed on the photoconductors 21 of the respective colors are transferred onto the intermediate transfer belt 11 by the respective primary transfer units 25 at the same timing and are superimposed on each other. As a result, a color toner image is formed on the intermediate transfer belt 11. Note that the toner remaining on the photosensitive member 21 after passing through the primary transfer region is scraped off by the cleaner 26.

  Paper as a recording member for image formation is pulled out from the paper feed cassette 13 or the manual feed unit 14 to the paper transport path 31 one by one as indicated by an arrow h in FIG. Then, the paper is conveyed along the paper conveyance path 31 toward the secondary transfer unit 35. The toner image superimposed on the intermediate transfer belt 11 is transferred to the conveyed paper in the secondary transfer unit 35. The sheet on which the toner image has been transferred is further conveyed upward to reach the fixing unit 36 where it is heated and pressurized. As a result, the toner is fixed on the paper. Then, the paper on which the image has been formed is discharged out of the machine.

  As the image formation is repeated, the photoreceptor 21 and the charging unit 22 gradually deteriorate. If you continue to use it as it is, the image quality will deteriorate, so it is recommended to replace it at an appropriate time. On the other hand, since the developer is added from the corresponding hopper 28, the developing unit 24 has a considerably longer life than the photoconductor 21. Therefore, in this embodiment, as shown in FIG. 2, the photosensitive member 21, the charging unit 22, and the cleaner 26 are combined to form a drum unit 51. The drum unit 51 is detachable from the developing unit 24 and is detachable from the main body of the color printer 1.

  Further, the developing unit 24 of this embodiment is in contact with and separated from the photoreceptor 21 as shown in FIGS. FIG. 2 shows an arrangement in which both the drum unit 51 and the developing unit 24 are attached to the color printer 1 and image formation is possible. At the time of image formation, a laser beam 54 is emitted from the irradiation surface 53 of the exposure unit 23 to the photosensitive member 21. FIG. 3 shows a state in which the developing unit 24 is moved in order to remove the drum unit 51.

  As shown in FIG. 2, the developing unit 24 is covered with a housing 56 that is partially opened, and a part of the developing roller 58 is exposed from the opening 57. The housing 56 of the developing unit 24 is rotatable within a certain range around the lower right rotation shaft 61 in the drawing. A spring 62 is provided in the upper left of the housing 56 in the drawing between the fixed portion in the machine and the developing unit 24 is pressed rightward in the drawing. As a result, in the state shown in FIG. 2, the developing roller 58 is arranged in contact with or very close to the surface of the photoreceptor 21. A seal member 63 is provided in the opening 57 of the housing 56. As a result, dust such as toner is prevented from scattering from between the developing roller 58 and the photosensitive member 21.

  The developing unit 24 of the present embodiment further includes a lever 64, a cam 65, a link 66, and a shutter 67, as shown in FIGS. The lever 64 can rotate around the rotation shaft 64 a, and the cam 65 is fixed to the lever 64. The cam 65 is in contact with the housing 56 and the link 66 of the developing unit 24. The link 66 is rotatable around a rotation shaft 66a near the center thereof, and a shutter 67 is attached to one end on the lower side in the drawing. In the state of FIG. 2, the irradiation surface 53 is exposed, and there is nothing that blocks the optical path of the laser light 54. The lever 64 shown in FIG. 2 is on the near side of the optical path of the laser beam 54 in the drawing and does not block the laser beam 54. Note that the shutter 67 is maintained horizontally between the state of FIG. 2 and the state of FIG.

  From the arrangement shown in FIG. 2, the arrangement shown in FIG. 3 is obtained by rotating the lever 64 approximately half counterclockwise in the drawing. The lever 64 is rotated by the operator prior to replacement of the drum unit 51. Then, the cam 65 interlocked with the lever 64 pushes the housing 56 and the upper portion of the link 66 leftward in the drawing. As a result, the housing 56 rotates counterclockwise in the drawing around the rotation shaft 61 against the pressing force of the spring 62. Further, the link 66 is rotated counterclockwise in the drawing when the upper portion is pushed, and the shutter 67 is slid rightward in the drawing. As a result, the irradiation surface 53 of the exposure unit 23 is covered with a shutter 67 as shown in FIG.

  Further, when the housing 56 is rotated, the developing roller 58 and the photosensitive member 21 are separated. As a result, in the arrangement shown in FIG. 3, the seal member 63 is separated from the photoconductor 21, so that toner or the like captured between them may be scattered around the periphery. In this embodiment, in this arrangement, since the irradiation surface 53 is covered by the shutter 67, there is no possibility of adhering to the irradiation surface 53 even if toner or the like is scattered. In this state, the operator pulls out the drum unit 51 and replaces it with a new drum unit 51. When the replacement of the drum unit 51 is completed, the lever 64 is returned to the original position, and the arrangement shown in FIG. 2 is obtained, so that image formation is possible. In the present embodiment, the cam 65 and the link 66 that are moved by the operation of the lever 64 constitute a developing unit moving unit.

  As described in detail above, according to the color printer 1 of the present embodiment, the lever 64 is rotated by the operator when the drum unit 51 is replaced. Then, the housing 56 and the link 66 of the developing unit 24 are rotated by the cam 65 interlocked with the lever 64. As a result, the developing roller 58 and the photosensitive member 21 are separated from each other, and the irradiation surface 53 of the exposure unit 23 is covered with the shutter 67. Therefore, it is possible to replace only the drum unit while leaving the developing device in the apparatus while preventing the foreign matter from adhering to the irradiation surface of the exposure apparatus.

"Second form"
Next, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. This embodiment is different from the first embodiment only in the configuration for separating the developing unit 24 and the photosensitive member 21, and common portions are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIGS. 4 to 6, the image forming unit of this embodiment includes a slide lever 71 and a shutter 72 attached thereto. In the present embodiment, the developing unit 24 does not have a rotation axis. The slide lever 71 is provided with a knob 73 on the front face in the drawing. An upper left slope portion 71 a of the slide lever 71 is a slope parallel to the right lower surface 56 a of the housing 56 of the developing unit 24.

  The shutter 72 is long enough to cover the irradiation surface 53 in the depth direction, and is fixed to the slide lever 71. The shutter 72 and the slide lever 71 are connected by connecting rods 74 provided at both ends of the front side and the back side in the drawing. Therefore, the slide lever 71 and the shutter 72 can be integrally slid along the side surface of the exposure unit 23 in the left-right direction in the drawing. The connecting rod 74 is provided outside the image forming area and does not block the optical path of the laser beam 54.

  In the image forming unit of this embodiment, the arrangement shown in FIG. 4 is an arrangement in which the photoconductor 21 and the developing roller 58 are in contact with each other, and normal image formation is possible. In the apparatus of this embodiment, when replacing the drum unit 51, the operator first slides the knob 73 leftward in the drawing. 4. Slide from the position of FIG. 4 to the position of FIG. 6 through the position of FIG. In the position of FIG. 5, the developing unit 24 has not moved from the position of FIG. 4, but the irradiation surface 53 of the exposure unit 23 is covered with a shutter 72. By adopting such an order, it is possible to reliably avoid the adhesion of foreign matters to the irradiation surface 53.

  In the position of FIG. 6, the spring 62 is pressed and contracted, and the developing unit 24 moves to the left in the drawing from the arrangement shown in FIG. That is, even after the inclined surface portion 71a of the slide lever 71 contacts the right lower surface 56a of the housing 56 of the developing unit 24, the slide lever 71 and the developing unit 24 are further slid together to achieve this arrangement. As a result, the developing unit 24 is located away from the photoreceptor 21. With this arrangement, the operator can take out and replace only the drum unit 51. Even in this arrangement, since the irradiation surface 53 is covered by the shutter 72, it is possible to reliably avoid the attachment of foreign matter to the irradiation surface 53.

  When the replacement is completed, the knob 73 is slid rightward and returned to the position shown in FIG. In this case, the position shown in FIG. 4 is obtained from the position shown in FIG. 6 through the position shown in FIG. That is, first, the developing unit 24 is moved to cover the opening 57 with the seal member 63, and then the irradiation surface 53 of the exposure unit 23 is exposed. Therefore, there is no possibility that the irradiation surface 53 is soiled even in this step. By returning to the position shown in FIG. 4, image formation can be performed again. In this embodiment, the slide lever 71 corresponds to the developing unit moving unit.

  As described above in detail, also in the color printer of this embodiment, the irradiation surface 53 is covered with the shutter 72 when the developing roller 58 and the photosensitive member 21 are separated, as in the first embodiment. Therefore, it is possible to replace only the drum unit while leaving the developing device in the apparatus while preventing foreign matter from adhering to the irradiation surface 53 of the exposure apparatus. Further, in this embodiment, the irradiation surface 53 can be covered before the developing unit 24 and the photosensitive member 21 are separated. Then, after the developing unit 24 is returned to a predetermined position, the cover of the irradiation surface 53 can be removed.

  In the first or second embodiment, the shutters 67 and 72 may have a box shape as shown in FIG. This is more effective because it can catch the falling foreign matter.

Further, during maintenance such as replacement of the drum unit 51 and cleaning of the inside of the apparatus, even if it is covered with the shutters 67 and 72, some dust or the like may adhere to the irradiation surface 53. Therefore, it is desirable to clean the irradiation surface 53 at the end of the maintenance work. Therefore, for example as a shutter 67 of the first embodiment, as shown in FIG. 8, may be assumed that the formation of the convex portion 82. The convex portion 82 has a guide shape for guiding the cleaning tool 81. This guide shape is provided within a range that does not block the optical path of the laser beam 54.

  In this embodiment, as shown in FIG. 9, a cleaning tool 81 having a groove 83 that fits the convex portion 82 along the longitudinal direction and a brush 84 provided at one end in the longitudinal direction is prepared for maintenance personnel. ing. Then, after all the operations are completed and the developing unit 24 and the shutter 67 are returned to the predetermined arrangement shown in FIG. 2, the brush 84 side faces downward as shown in FIG. Match 83. If the cleaning tool 81 is moved back and forth along the convex portion 82 in the depth direction in the figure, the irradiation surface 53 can be reliably cleaned to the back. When the cleaning is completed, the cleaning tool 81 is removed. For the shutter 72 of the second embodiment, a similar convex portion may be formed on the left end surface in FIG. The convex portion and the groove may be reversed.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the first embodiment, the irradiation surface can be shielded prior to the separation of the developing unit 24. In that case, for example, as shown in FIG. 10, the cam 91 may be formed by dividing its functional portion in the axial direction. The cam 91 includes a cam portion 92 that moves the lever 66 and a cam portion 93 that moves the housing 56. In this way, the cam portion 92 and the cam portion 93 can be operated with a time difference in this order in conjunction with the rotation of the lever 64. Alternatively, the size of the shutter 67 and the lever ratio of the link 66 may be simply adjusted.

  In these embodiments, the developing roller is in contact with the photosensitive member. However, the present invention can also be applied to a case where development is performed in a very close arrangement without contact. Further, instead of using the exposure unit 23 common to each color, the present invention can also be applied to one having each exposure unit for each color. It can also be applied to a monochrome image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Color printer 21 Photoconductor 22 Charging part 23 Exposure part 24 Developing part 51 Drum unit 64 Lever 65 Cam 66 Link 67, 72 Shutter 71 Slide lever 82 Convex part

Claims (5)

A photosensitive member, a charging unit that uniformly charges the surface of the photosensitive member, and an exposure unit that forms an electrostatic latent image by irradiating light on the charged surface of the photosensitive member from an irradiation surface are formed. by supplying toner to the electrostatic latent image meet the image forming apparatus and a developing unit for forming a toner image,
A drum unit that is detachable from the image forming apparatus, includes the photosensitive member and the charging unit, and does not include the exposure unit and the developing unit;
A developing unit moving unit that moves the developing unit between a developing position where the electrostatic latent image formed on the photoconductor can be developed and a remote position away from the photoconductor;
In conjunction with the movement of the developing unit by the developing unit moving unit, the developing unit moves between a shielding position that covers the irradiation surface of the exposure unit and an uncovered exposure position, and when the developing unit is in the developing position, the exposure position And having a shutter that is a shielding position when the developing portion is at the separation position,
The shutter is
When the developing unit moves from the developing position to the separation position, it moves from the exposure position to the shielding position prior to that,
An image forming apparatus, wherein when the developing unit moves from the separation position to the developing position, the developing unit moves from the shielding position to the exposure position thereafter. A photosensitive member, a charging unit that uniformly charges the surface of the photosensitive member, and an exposure unit that forms an electrostatic latent image by irradiating light on the charged surface of the photosensitive member from an irradiation surface are formed. by supplying toner to the electrostatic latent image meet the image forming apparatus and a developing unit for forming a toner image,
A drum unit that is detachable from the image forming apparatus, includes the photosensitive member and the charging unit, and does not include the exposure unit and the developing unit;
A developing unit moving unit that moves the developing unit between a developing position where the electrostatic latent image formed on the photoconductor can be developed and a remote position away from the photoconductor;
In conjunction with the movement of the developing unit by the developing unit moving unit, the developing unit moves between a shielding position that covers the irradiation surface of the exposure unit and an uncovered exposure position, and when the developing unit is in the developing position, the exposure position And having a shutter that is a shielding position when the developing portion is at the separation position,
Said shutter, when in the Exposure position, image, wherein a guide shape that guides to move along the exposed portion by attaching a cleaning tool for cleaning the exposed portion is formed Forming equipment. A photosensitive member, a charging unit that uniformly charges the surface of the photosensitive member, and an exposure unit that forms an electrostatic latent image by irradiating light on the charged surface of the photosensitive member from an irradiation surface are formed. by supplying toner to the electrostatic latent image meet the image forming apparatus and a developing unit for forming a toner image,
A drum unit that is detachable from the image forming apparatus, includes the photosensitive member and the charging unit, and does not include the exposure unit and the developing unit;
A developing unit moving unit that moves the developing unit between a developing position where the electrostatic latent image formed on the photoconductor can be developed and a remote position away from the photoconductor;
In conjunction with the movement of the developing unit by the developing unit moving unit, the developing unit moves between a shielding position that covers the irradiation surface of the exposure unit and an uncovered exposure position, and when the developing unit is in the developing position, the exposure position And having a shutter that is a shielding position when the developing portion is at the separation position,
The image forming apparatus, wherein the shutter is fixed to the developing unit moving unit. It met image forming apparatus according to claim 1 or claim 2,
Together with the cam portion to move by pushing the developing unit moves by operation of the steering authors included in the developing unit moving unit,
An image forming apparatus comprising that you have links for moving the shutter is pushed together with the developing unit is provided by the cam portion. Met image forming apparatus according to claim 1, any one of up to claim 4,
The exposure unit is disposed below the development portion of the photoreceptor by the development unit;
The image forming apparatus according to claim 1, wherein the shutter has a box shape with an open top.

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