JP4664728B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic process such as a copying machine, a printer, or a facsimile machine, and more particularly to an image forming apparatus provided with a protective cover for protecting an image carrier such as a photosensitive drum.

  Generally, in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, when a paper feed failure such as a paper jam occurs, the developing unit is removed from the image forming apparatus in order to deal with the paper feed failure. May be performed. Since the developing unit faces the photosensitive drum, when the developing unit is removed, the photosensitive drum is exposed, and the photosensitive drum is accidentally touched during the paper feeding failure treatment. Problems with the drum may occur.

  For this reason, when the developing unit is removed from the image forming apparatus, a protective cover (shutter) is closed to protect the photosensitive drum. That is, when the developing unit is mounted on the image forming apparatus, the shutter is opened so that the developing unit and the photosensitive drum face each other, and when the developing unit is removed from the image forming apparatus, the shutter closes and the photosensitive drum is removed. The ones that are designed to be protected are known.

  In general, the above shutter is a thin member, so it is easily deformed. If the shutter is deformed, for example, the optical path of the laser beam may be interrupted when exposing the photosensitive drum, and the deformation of the shutter is prevented as much as possible. There is a need to.

  Conventionally, in order to prevent the deformation of the shutter, there is a structure in which a large number of ribs are arranged in a substantially vertical direction on the inner surface of the shutter to improve the strength of the shutter (see Patent Document 1). Further, in order to prevent the deformation of the shutter, the shutter 31 is formed by connecting the rotating arm and the shutter main body, and at the connecting portion, there is provided a play that allows the shutter main body to move in the longitudinal direction. Even if 33 expands in the longitudinal direction, both ends in the longitudinal direction of the shutter body are prevented from being pressed against the rotating arm, and the shutter body is prevented from being deformed into a V shape ( Patent Document 2).

Japanese Patent Laid-Open No. 2001-13847 JP 2000-131903 A

  However, in Patent Document 1, since a large number of ribs are arranged in parallel on the inner surface of the shutter, the shutter becomes inevitably thick, and the strength of the shutter can be improved, but when the shutter is retracted (when opened) ) Needs to be widened, resulting in a problem that the image forming apparatus itself is increased in size and cost.

  Further, in Patent Document 2, only the V-shaped deformation caused by the expansion of the shutter in the longitudinal direction due to heat is prevented, and any deformation in the other direction when the thickness of the shutter is thin is considered. In addition, there is a problem that it is difficult to prevent the problem of blocking the optical path due to the deformation of the shutter.

  In any case, both Patent Documents 1 and 2 have a problem that it is difficult to reduce the thickness of the shutter and prevent its deformation.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus that can reduce the thickness of a shutter and prevent the deformation of the shutter.

Accordingly, in order to solve the above problems, the present invention provides an image carrier unit having an image carrier on which an electrostatic latent image is formed, and a developing unit that develops the electrostatic latent image while facing the image carrier. And a protective cover that protects the surface of the image carrier by being positioned at a shielding position when at least one of the image carrier unit and the developing unit is removed from the image forming apparatus main body. When the developing unit and the image carrier unit are attached to the image forming apparatus main body, the protective cover is positioned at the retracted position so that the developing unit and the image carrier face each other. An optical path of exposure light that forms the electrostatic latent image when positioned is disposed in the vicinity of the protective cover, and when the protective cover is in the retracted position, Have a correcting mechanism for correcting the cover in a direction away from said optical path, said correction mechanism for correcting said protective cover in synchronism with the movement of the protective cover is the retracted position the protective cover in a direction away from said optical path The correction mechanism includes a wire member that extends in the axial direction of the image carrier and is rotated around a rotation fulcrum, and rib portions that are formed on the protective cover and are positioned at both axial ends of the image carrier. The wire member includes a coaxial portion coaxial with the supporting fulcrum of the protective cover, and a contact portion that extends parallel to the coaxial portion with a step and intersects the axial direction and is located outside the coaxial portion. The rib portion is formed at a position corresponding to the contact portion, and the wire member rotates around the rotation fulcrum in synchronization with the movement of the protective cover around the support fulcrum. Is characterized in that the rib portion and the protective cover is positioned at the retracted position by the contact portion is to be pressed Te.

  As described above, in the image forming apparatus of the present invention, when the protective cover is located at the retracted position, the protective cover is corrected in the direction away from the optical path. Therefore, since the shutter is thin, the shutter is deformed. However, the optical path is not obstructed by the shutter. That is, there is an effect that even if the shutter is thinned, the deformation can be substantially prevented.

  In the present invention, in synchronization with the movement of the protective cover, when the protective cover is in the retracted position, the protective cover is corrected in the direction away from the optical path. Therefore, the shutter is corrected only when the protective cover is in the retracted position. Therefore, there is an effect that unnecessary pressure is not applied to the shutter.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. The illustrated image forming apparatus 10 includes a photosensitive drum 11 and a developing unit 12, and at least the developing unit 12 includes an image forming apparatus main body 13. It can be removed from. As shown in the figure, an exposure device 14, a developing unit 12, a transfer roller 15, and a cleaning unit 16 are arranged around the photosensitive drum 11, and the developing roller 12 a of the developing unit 12 faces the photosensitive drum 11. Yes.

  When image formation (for example, copying) is performed, a sheet is fed from the sheet feeding tray 17 through a sheet conveyance path 18 to a nip portion between the photosensitive drum 11 and the transfer roller 15. On the other hand, the surface of the photosensitive drum 11 is uniformly charged by the charger 14 and then exposed by the laser beam from the exposure unit 19, so that an electrostatic latent image is formed on the photosensitive drum 11. The laser light is irradiated onto the photosensitive drum 11 through an optical path indicated by symbol P in the drawing. At this time, the laser light passes through the vicinity of a protective cover described later and is irradiated onto the photosensitive drum 11. Is done.

  The electrostatic latent image on the photosensitive drum 11 is developed by the developing roller 12a to become a toner image, and this toner image is transferred to the paper by the transfer roller 15. Then, the sheet passes through the sheet conveyance path 20 to the fixing unit 21 where the toner image on the sheet is fixed, and the sheet is discharged to the discharge tray 23 through the discharge path 22.

  As will be described later, a protective cover (hereinafter referred to as a shutter) 31 is attached to the drum unit. The shutter 31 moves to the retracted position when the developing unit 12 is mounted on the image forming apparatus main body 13. Then, the photosensitive drum 11 and the developing roller 12a face each other.

  In the illustrated example, as will be described later, the shutter 31 has first and second shutter portions 32 and 33, and at the retracted position, the shutter portions 32 and 33 overlap each other with a gap therebetween (overlapping). ), The photosensitive drum 11 is irradiated with laser light through the gap. On the other hand, when the developing unit 12 is detached from the image forming apparatus main body 13, the shutter 31 moves to the shielding position and the photosensitive drum 11 is shielded by the shutter 31. In this state, as will be described later, the shutter portions 32 and 33 have a single plate shape.

  2 is a cross-sectional view showing a state in which a shutter provided in the drum unit is closed (that is, a state where the shutter is located at a shielding position), and FIG. 3 is an enlarged view of a portion indicated by symbol A in FIG. FIG. 3 is a perspective view showing a state where a shutter is closed. The shutter part 32 is supported by the drum unit housing 36 by a shutter holding shaft part 34 (see FIG. 3) formed on a wire member, which will be described later. On the other hand, the shutter part 33 is interlocked (synchronized) with the shutter part 32 by a link mechanism 35. When the shutter 31 is closed, the shutter portion 33 is positioned below the shutter portion 32, and the photosensitive drum 11 is shielded by the shutter portions 32 and 33.

  FIG. 5 is a perspective view showing a wire member for correcting the shutter portion 32. The wire member 41 extends along the axial direction of the photosensitive drum 11, and rotates to the drum unit housing 36 with both ends thereof as rotation fulcrums 42. Supported as possible. As shown in FIG. 5, the wire member 41 has a main body portion 43 extending in the axial direction of the photosensitive drum 11, and both end portions of the main body portion 43 are bent in a direction intersecting (orthogonal) with the main body portion 43. Thus, the correction part 44 is formed. Then, the correction portion 44 is bent again in a direction intersecting the main body portion 43 to form a link portion 37, and both end portions of the link portion 37 serve as the rotation fulcrum 42 described above.

  A step 44a is formed at a substantially central portion of the correction portion 44, and the correction portion 44 is positioned on the abutment portion 45 located on the main body portion 43 side and the rotation fulcrum 42 (that is, the link portion 37) side. And a coaxial part 46. The coaxial portion 46 becomes the shutter holding shaft portion 34 described above. The contact portion 45 is positioned at a position farther from the coaxial portion 46 than the main body portion 43. That is, the wire member 41 is supported by the drum unit housing 36 so that the coaxial portion 46 is coaxial with the rotation fulcrum (shutter holding shaft portion 34) of the shutter portion 32.

  As shown in FIG. 4, shutter correction rib portions 51 are formed on both end sides of the shutter portion 32, and as shown in enlarged views in FIGS. It is formed in the corresponding position. In the state where the shutter 31 is closed, the wire member 41 is rotated around the rotation fulcrum 42 (that is, the rotation fulcrum 34) and is in the state shown in FIG. Since the step 44 a is formed at the boundary with the contact portion 45, the contact portion 45 is not in contact with the rib portion 51, and is not between the contact portion 45 and the rib portion 51. A clearance R exists.

  Now, when the developing unit 12 is mounted on the image forming apparatus main body 13, the shutter 31 is retracted in the direction indicated by the solid line arrow in FIG. On the other hand, the wire member 41 rotates around the rotation fulcrum 42 in the direction indicated by the solid line arrow in FIG. 8 is a cross-sectional view showing a state in which the shutter 31 is positioned at the retracted position, FIG. 9 is an enlarged view showing a portion indicated by reference numeral B in FIG. 8, and FIG. 10 is a perspective view showing a state in which the shutter 31 is opened. FIG. 8 to 10, when the wire member 41 rotates around the rotation fulcrum 42, the contact portion 45 moves in the direction of the rib portion 51 because the shutter holding shaft portion 34 and the coaxial portion 46 are coaxial. In other words, the contact portion 45 moves in a direction in which the clearance R is eliminated.

  When the rib portion 51 does not exist, the contact portion 45 moves to the position indicated by the broken-line circle in FIG. 9, but when the rib portion 51 exists, as indicated by the solid-line circle in FIG. The abutment portion 45 abuts on the rib portion 51, and the abutment portion 45 presses the rib portion 51. That is, the shutter portion 32 is pushed outward (in a direction away from the shutter portion 33) by the contact portion 45, and the interval between the shutter portion 32 and the shutter portion 33 is increased.

  In this way, the interval between the shutter unit 32 and the shutter unit 33 is increased, that is, when the optical path of the laser beam is defined between the shutter unit 32 and the shutter unit 33 at the retracted position, the shutter unit 32 is As a result of being pushed and corrected in the direction away from the optical path, the optical path is not obstructed by the shutter portion 32. In other words, the optical path is not obstructed by the deformation of the shutter portion 32.

  Since the deformation of the shutter unit 32 is corrected in this manner, the deformation of the shutter unit 32 can be dealt with even if the thickness of the shutter unit 32 is reduced. It is possible to prevent the optical path from being interrupted regardless of the warp or the like.

  In the above-described example, the shutter 31 includes the shutter portions 32 and 33, the photosensitive drum 11 is shielded by the shutter portions 32 and 33 at the shielding position, and between the shutter portion 32 and the shutter portion 33 at the retracted position. Although the optical path is defined, even when the shutter 31 is configured by a single shutter portion and the optical path is formed between the shutter 31 and the photosensitive drum 11, the shutter 31 is similarly set outward. If pressed, the optical path is not hindered by the deformation of the shutter 31. In the above example, the rib mechanism 51 and the wire member 41 constitute a correction mechanism.

  In the above-described example, the example in which the photosensitive drum is protected by the shutter when the developing unit is detached from the image forming apparatus main body has been described. However, the drum unit is also detachable from the image forming apparatus main body. When one of the shutters is removed from the image forming apparatus main body, the shutter may be positioned at a shielding position to protect the surface of the photosensitive drum. When the developing unit and the drum unit are attached to the image forming apparatus main body, the shutter is positioned at the retracted position so that the developing unit and the image carrier face each other.

  When the shutter is in the retracted position, the shutter is corrected in a direction away from the optical path of the exposure light. Therefore, the shutter is thin, so even if the shutter is deformed, the optical path is not obstructed by the shutter. The present invention can be applied to an image forming apparatus in which an optical path is defined near a shutter at a position.

It is sectional drawing which shows the image forming apparatus by Example 1 of this invention. It is sectional drawing which shows the state which closed the shutter with which the drum unit was equipped. It is a figure which expands and shows the part shown with the code | symbol A in FIG. It is a perspective view which shows the state which closed the shutter with which the drum unit was equipped. It is a perspective view which shows the wire member for correcting a shutter. It is a figure which expands and shows the part shown with the code | symbol C1 in FIG. It is a figure which expands and shows the part shown by the code | symbol C2 in FIG. It is sectional drawing which shows the state in which the shutter was located in the retracted position. It is a figure which expands and shows the part shown with the code | symbol B in FIG. It is a perspective view which shows the state which opened the shutter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photosensitive drum 12 Developing unit 13 Image forming apparatus main body 14 Exposure device 15 Transfer roller 16 Cleaning unit 17 Paper feed trays 18, 20 Paper transport path 19 Exposure unit 21 Fixing unit 22 Paper discharge path 23 Paper discharge tray 31 Protective cover (shutter)
32, 33 Shutter part 41 Wire member 42 Rotation fulcrum 43 Main body part 44 Correction part 44a Step 45 Contact part 46 Coaxial part 51 Rib part

Claims (1)

An image carrier unit having an image carrier on which an electrostatic latent image is formed; a developing unit that faces the image carrier and develops the electrostatic latent image; and at least one of the image carrier unit and the development unit A protective cover that protects the surface of the image carrier when one is removed from the main body of the image forming apparatus and is protected by the developing unit and the image carrier unit. In the image forming apparatus which is positioned in the retracted position when attached to the apparatus main body and faces the developing unit and the image carrier,
An optical path of exposure light that forms the electrostatic latent image when the protective cover is located at the retracted position is disposed in the vicinity of the protective cover,
The protective cover when the protective cover is in the retracted position have a correcting mechanism for correcting a direction away from said optical path,
The correction mechanism corrects the protective cover in a direction away from the optical path when the protective cover is in the retracted position in synchronization with the movement of the protective cover;
The correction mechanism includes a wire member that extends in the axial direction of the image carrier and is rotated about a rotation fulcrum, and rib portions that are formed on the protective cover and are positioned at both axial ends of the image carrier.
The wire member includes a coaxial portion coaxial with the supporting fulcrum of the protective cover, and a contact portion that extends parallel to the coaxial portion with a step and intersects the axial direction and is located outside the coaxial portion. And formed,
The rib portion is formed at a position corresponding to the contact portion,
In synchronization with the movement of the protective cover about the support fulcrum, the rib member is pressed by the contact portion when the wire member rotates about the rotation fulcrum and the protective cover is positioned at the retracted position. An image forming apparatus characterized by being configured as described above .

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