JP2005148702A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing an impact force generated when a developing unit and a drum unit abut against each other. <P>SOLUTION: An engagement projection part 124 is formed on the side of the developing unit 120 and a buffer means 130 is provided on the side of an image forming apparatus body 101; when an engaged oblique surface 132A of a pressing member 132 consisting the buffer means 130 and an engaging oblique surface 132A of the engagement projection part 124 engage each other and the developing unit 120 is inserted in the insertion direction, a reaction force of a 1st spring member 131 is transmitted in the opposite direction. Consequently, the inserting speed of the developing unit 120 is reduced right before the developing unit 120 abuts against the drum unit 110 to obtain buffer effect. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a developing unit and a drum unit, or a coupling unit formed by detachably coupling a drum unit and a developing unit.

  As a conventional image forming apparatus, as shown in FIG. 9, a drum unit 10 having a photosensitive drum 1 and a developing unit 20 having a developing sleeve (mag roller) 2 serving as an image forming unit are configured separately. There is something. In this type of image forming apparatus, a drum unit 10 and a developing unit 20 are detachably provided in an image forming apparatus main body 11.

  After the electrostatic latent image is formed on the surface of the photosensitive drum 1 of the drum unit 10 described above, toner is blown onto the drum surface by, for example, jumping development to form a toner image composed of a thin toner layer. . In such development, the developing sleeve 2 is arranged at a certain distance from the surface of the photosensitive drum 1 (hereinafter referred to as a developing gap). As shown in FIG. 9, in the case where the drum unit 10 and the developing unit 20 are configured separately, means for holding the developing gap is required.

  FIG. 10 shows a structure for maintaining a developing gap between the surface of the photosensitive drum 1 rotatably supported on the drum unit 10 side and the developing sleeve 2 rotatably supported on the developing unit 20 side. Is shown. As shown in FIG. 10, the developing sleeve 2 is set so that the rotating shaft 3 thereof is parallel to the rotating shaft of the photosensitive drum 1. Further, at both ends of the developing sleeve 2, a gap forming roller 4 for defining a developing gap is provided coaxially with the developing sleeve 2. The radius of the gap forming roller 4 is set to be longer than the radius of the developing sleeve 2 by the developing gap. The clearance between the photosensitive drum 1 and the developing sleeve 2 can be kept constant by bringing the peripheral surface of the gap forming roller 4 into contact with the peripheral surface of the photosensitive drum 1.

  As described above, in the image forming apparatus in which the drum unit 10 and the developing unit 20 are configured separately, when the developing unit 20 is inserted in a state where the drum unit 10 is mounted on the image forming apparatus main body 11, the photosensitive drum In order to suppress the impact when the gap forming roller 4 directly hits 1, measures are taken such as changing the system of the developing unit 20 or taking an insertion path so that the impact force does not act when the developing unit 20 is inserted. ing. However, when these measures are taken, the inserting operation of the developing unit becomes unnatural or the certainty of the impact suppressing effect is low.

  Further, in such an image forming apparatus, in order to bring the gap forming roller 4 into contact with the peripheral surface of the photosensitive drum 1 of the drum unit 10 with a predetermined pressure, as shown in FIG. An urging means 30 is provided for pressing toward the front. The urging unit 30 includes a pressing member 32 provided at a free end of a spring 31 whose base end is fixed to the image forming apparatus main body 11 side. A pressed wall portion 21 that receives the pressing member 32 is provided at the bottom of the developing unit 20. In this manner, the pressing member 32 is pressed against the pressed wall portion 21 so that the developing unit 20 is urged toward the drum unit 10 (insertion direction indicated by a thick arrow in the figure).

  As shown in FIG. 11, as an image forming apparatus, a drum unit 10 having a photosensitive drum 1 and a developing unit 20 joined to the drum unit 10 are detachably coupled with screws or the like ( Some have a coupling unit 40. In this type of image forming apparatus, the process cartridge 40 and the toner container 25 constitute an image forming unit.

  FIG. 12 shows how the process cartridge 40 is taken out from the image forming apparatus main body 11. The process cartridge 40 is opened and removed from a part of the exterior cover 13 that is opened. The process cartridge 40 is attached / detached by guiding a boss 23 provided on the process cartridge 40 side along a rail groove (not shown) provided in the image forming apparatus main body 11 to enable smooth attachment / detachment. .

Further, as another improved technique, an elastic member is interposed between the drum unit and the image forming apparatus main body, and the impact when the developing unit comes into contact with the drum unit is mitigated by the elastic member ( For example, see Patent Document 1.)
Japanese Unexamined Patent Publication No. 3-84564 (page 4, FIG. 1)

  However, in the above-described conventional example in which an elastic member is interposed between the drum unit and the image forming apparatus main body, the moving speed when the developing unit abuts against the drum unit is not restricted. When the abutting speed is high, the impact may damage the drum surface or deform the gap forming roller. Further, there is a risk that the toner may be blown out from the developing unit due to an impact.

  Further, in the case of an image forming apparatus provided with a process cartridge, when the process cartridge is inserted at a rapid speed, a large impact force is applied to the process cartridge, so that an indentation is generated in the toner layer of the developing sleeve in the process cartridge. An excessive impact force is also applied between the gear for driving the photosensitive drum or the like and the drive gear on the image forming apparatus main body side, causing a gear breakage.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of reducing the impact and insertion speed of the developing unit or the coupling unit, reducing the impact force, and protecting the drum surface and the like.

  Another object of the present invention is to mitigate the impact force to prevent the toner from blowing out from the developing unit, or to mitigate the impact on the coupling unit to cause an image defect or the occurrence of gear breakage. An object of the present invention is to provide an image forming apparatus capable of preventing the above.

  The invention described in claim 1 relates to an image forming apparatus in which a drum unit having a photosensitive drum and a developing unit having a developing sleeve are detachably provided on the main body of the image forming apparatus. In the image forming apparatus according to the present invention, the image forming apparatus main body is provided with a buffer unit that propagates a repulsive force in a direction opposite to the direction in which the developing unit is inserted with respect to the developing unit inserted into the image forming apparatus main body. It is characterized by that.

  The invention according to claim 2 relates to the image forming apparatus according to claim 1. In the image forming apparatus according to the present invention, the buffer means expands and contracts toward the insertion direction below the direction opposite to the insertion direction of the developing unit arrangement space in the image forming apparatus main body. A pressing portion is provided at a free end of one spring portion, a base end is fixed to the image forming apparatus main body below the pressing portion, a free end is fixed to a lower portion of the pressing portion, and expands and contracts in the vertical direction. A second spring portion is provided, and an inclined surface for engagement is formed on the upper portion of the pressing portion, and the pressing portion is positioned on the lower side opposite to the inserting direction of the developing unit at a position before the developing unit is inserted to a specified position. An engaging slope that contacts the engaged slope of the part is formed, and the first spring part is stretched as the developing unit is inserted, and a reaction force is generated in the developing unit in the direction opposite to the insertion direction. Set to let It is characterized in that.

  The invention described in claim 3 relates to the image forming apparatus described in claim 1 or claim 2. The image forming apparatus according to the present invention is characterized in that the first spring portion and the second spring portion are coil springs.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the buffer means includes a damper device provided in at least one of the image forming apparatus main body and the developing unit. When the developing unit is inserted into the image forming apparatus main body, the damper device is formed on at least one of the developing unit and the image forming apparatus main body before the developing unit is inserted into a predetermined position. Abutting on the abutting portion, a repulsive force on the opposite side to the insertion direction is transmitted to the developing unit.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus in which a coupling unit formed by detachably coupling a drum unit having a photosensitive drum and a developing unit joined to the drum unit is inserted into the main body of the image forming apparatus. Is. When the coupling unit is inserted into the image forming apparatus main body, buffer means for propagating a repulsive force on the opposite side of the insertion direction to the coupling unit is provided on at least one of the image forming apparatus main body and the coupling unit. Provided.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the buffer means includes a damper device provided in at least one of the image forming apparatus main body and the coupling unit. When the coupling unit is inserted into the image forming apparatus main body, the damper device is formed on at least one of the coupling unit and the image forming apparatus main body before the coupling unit is inserted into a predetermined position. Abutting on the abutting portion, a repulsive force opposite to the insertion direction is propagated to the coupling unit.

  According to the present invention, it is possible to realize an image forming apparatus capable of reducing the impact and insertion speed of the developing unit or the coupling unit to zero or reducing the impact force and protecting the drum surface and the like.

  In addition, according to the present invention, it is possible to prevent the toner from blowing out from the developing unit by reducing the impact force.

  Furthermore, according to the present invention, the biasing means for pressing the developing unit in the inserting direction can be used as the buffering means, so that the structure is not complicated and the apparatus is increased in size. Can be prevented.

  Furthermore, according to the present invention, it is possible to mitigate the impact on the coupling unit and prevent image defects or gear breakage.

Hereinafter, an image forming apparatus according to the best mode for carrying out the present invention will be described.
[First Embodiment]
In the image forming apparatus according to the first embodiment, a drum unit having a photosensitive drum and a developing unit having a developing sleeve are detachably provided on the main body of the image forming apparatus. In the image forming apparatus according to the present embodiment, the image forming apparatus main body includes a buffer unit that propagates a repulsive force to the side opposite to the inserting direction of the developing unit with respect to the developing unit inserted into the image forming apparatus main body. On the side.

  In the structure of the buffer means, a pressing portion is provided at the free end of the first spring portion that expands and contracts in the insertion direction below the direction opposite to the insertion direction of the developing unit arrangement space in the image forming apparatus main body. Under the pressing portion, a base end is fixed to the image forming apparatus main body, a free end is fixed to a lower portion of the pressing portion, and a second spring portion that expands and contracts in the vertical direction is provided. Further, an engaged slope is formed on the upper portion of the pressing portion.

  On the other hand, on the lower side opposite to the direction in which the developing unit is inserted, an engaging slope that contacts the engaged slope of the pressing portion is formed at a position before the developing unit is inserted to the specified position. At this time, the engaged inclined surface and the engaging inclined surface come into contact with each other, so that an engaging relationship is established between the developing unit and the image forming apparatus main body, and the first spring portion is extended as the developing unit is inserted. The reaction force is set to be generated toward the opposite side of the insertion direction with respect to the developing unit. In addition, it is preferable that an above-described 1st spring part and the said 2nd spring part consist of coil springs.

With such a configuration, when the developing unit is mounted on the image forming apparatus main body, it is possible to reduce the impact of the developing unit on the photosensitive drum. Further, according to the present embodiment, it is possible to prevent the toner from blowing out from the developing unit by reducing the impact force.
[Second Embodiment]
In the image forming apparatus according to the second embodiment, a coupling unit (hereinafter referred to as a process cartridge) in which a drum unit having a photosensitive drum and a developing unit joined to the drum unit are detachably coupled by screws or the like. Called). If the process cartridge is replaced, the apparatus can be maintained. In this embodiment, the image forming apparatus main body is provided with a buffering means for propagating a repulsive force opposite to the process cartridge insertion direction when the process cartridge is inserted.

  The buffer means has a damper device provided in the process cartridge (or the image forming apparatus main body), and when the process cartridge is inserted into the image forming apparatus main body, the process cartridge is inserted into a specified position. Thus, the damper device contacts the contact portion formed on the image forming apparatus main body (or the process cartridge), and the repulsive force on the side opposite to the insertion direction is transmitted to the process cartridge.

  With such a configuration, the impact on the process cartridge can be reduced when the process cartridge is mounted on the image forming apparatus main body.

Hereinafter, details of an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic and the ratio of dimensions of each member is different from the actual one. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.
(Schematic configuration of image forming apparatus)
First, an outline of the image forming apparatus 100 will be described with reference to FIGS. 1 and 2. 1 is a perspective view of a main part showing a state in which the developing unit 120 is inserted in the image forming apparatus 100 according to the present embodiment, and FIG.

  As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present embodiment includes a drum unit 110 and a developing unit 120 that are detachably attached to the image forming apparatus main body 101. The drum unit 110 includes a photosensitive drum 111 that is driven to rotate. The developing unit 120 includes a toner container 121 that stores toner containing a magnetic material, and a developing sleeve 122 that supplies toner to the electrostatic latent image formed on the photosensitive drum 111 for development. Yes.

  On the drum unit 110 side, a rotation drive gear (not shown) that meshes with a rotation drive transmission gear (not shown) provided on the image forming apparatus main body 101 side is provided on the rotation shaft 111 </ b> A of the photosensitive drum 111. Further, the developing unit 120 is held in a state of being pressed by the buffer unit 130 that also serves as an urging unit toward the drum unit 110. In this embodiment, the drum unit 110 and the developing unit 120 are arranged in the horizontal direction, and the developing unit 120 is set to a slightly higher position.

  In the above, the case where the drum unit 110 and the developing unit 120 are configured separately has been described. However, the configuration of the process cartridge 140 in which the drum unit 110 and the developing unit 120 are integrated with screws or the like is also omitted. The same is true (see FIG. 8).

The image forming apparatus 100 according to the present exemplary embodiment includes an image forming unit (not illustrated) that transfers a toner image onto a sheet-like recording material that is fed from a sheet feeding tray (not illustrated) and conveyed along a sheet conveyance path, and the image. A fixing device (not shown) that fixes the toner image onto the recording material onto which the toner image has been transferred by the forming unit, and a discharge unit that discharges the recording material on which the toner image has been fixed through the fixing device onto a paper discharge tray, and the like. It is roughly structured.
(Drum unit configuration)
The drum unit 110 includes the above-described photosensitive drum 111 at the lower portion facing the developing unit 120. The photosensitive drum 111 is pivotally supported on the drum unit 110 by a rotating shaft 111A. Above the photosensitive drum 111 in the drum unit 110, a charger, a cleaner, a static eliminator, etc., not shown, are arranged. Further, for example, laser light can enter the photosensitive drum 111 from an exposure device (not shown). The drum unit 110 is inserted and mounted in the image forming apparatus main body 101 along a guide rail (not shown) provided on the image forming apparatus main body 101 side.
(Development unit configuration)
As shown in FIG. 2, the developing unit 120 is provided with a developing sleeve 122 facing the photosensitive drum 111 with a predetermined developing gap at the lower part on the side facing the photosensitive drum 111. In addition, a toner storage container 121 that stores toner is provided on the side of the developing unit 120 opposite to the side facing the photosensitive drum 111. A toner supply means (not shown) such as a paddle is provided between the toner container 121 and the developing sleeve 122 to supply toner to the developing sleeve 122 side.

  As shown in FIG. 1, guide convex portions 123 projecting sideways are formed on both side surfaces of the developing unit 120. The guide convex portion 123 is guided along a guide rail (not shown) formed on the image forming apparatus main body 101 side.

Further, as shown in FIG. 3, an engaging convex portion 124 that protrudes obliquely downward is formed on the outer side of the lower portion of the developing unit 120 where the toner storage container 121 is provided. The engaging convex portion 124 is a slide inclined so that an engaging slope 124A that engages an engaged slope 132A of the pressing member 132, which will be described later, a bottom surface 124B, and a distal end portion of the pressing member 132, which will be described later, are easy to slide. It has an inclined surface 124C and a pressed surface 124D that abuts against the tip of a pressing member 132, which will be described later, and transmits a biasing force in the insertion direction.
(Process cartridge configuration)
As shown in FIG. 8, in the process cartridge 140, a drum unit 110 having a photosensitive drum 111 and a developing unit 120 joined to the drum unit 110 are detachably coupled by screws or the like (not shown). . The process cartridge 140 is inserted into the image forming apparatus main body 101. In the process cartridge 140, the photosensitive drum 111 and the developing sleeve 122 face each other while maintaining a predetermined developing gap.
(Configuration of buffer means)
[First embodiment]
Next, the structure of the buffer means 130 of the first embodiment will be described with reference to FIGS. The buffer means 130 has a function as an urging means as described above.

  As shown in FIGS. 2 and 3, the buffer unit 130 is provided in the stepped portion 102 formed in the image forming apparatus main body 101. Here, the structure of the stepped portion 102 will be briefly described. The step 102 is provided so as to be positioned at a lower portion of the developing unit 120 opposite to the developing sleeve 122 when the developing unit 120 is mounted in the image forming apparatus main body 101. The step portion 102 includes a horizontal wall portion 102A along the horizontal direction and a vertical wall portion 102B that rises from an edge portion of the horizontal wall portion 102A.

  The buffer means 130 has a first spring portion 131 having one end fixed to the vertical wall portion 102B side, a pressing member 132 fixed to the free end of the first spring portion 131, and an upper end at the lower portion of the pressing member 132. And a second spring part 133 having a lower end fixed to the horizontal wall part 102A. The first spring portion 131 and the second spring portion 132 are constituted by coil springs.

  The pressing member 132 has an engaged slope 132A formed at the top. The engaged slope 132A is formed so as to face the side opposite to the direction in which the developing unit 120 is inserted. Further, a descending slope 132B is formed from the upper edge of the engaged slope 132A to the insertion direction side of the developing unit 120. Further, a slide wall portion 132 </ b> C extending from the lower edge of the engaged slope 132 </ b> A along the axial direction of the first spring portion 131 and slidable with respect to the first spring portion 131 is formed.

  Here, the operation and operation of the image forming apparatus 100 will be described.

  The image forming apparatus 100 according to the first embodiment has the following operation when the developing unit 120 is inserted and attached to the image forming apparatus main body 101 with the drum unit 110 attached to the image forming apparatus main body 101. .

  That is, as shown in FIG. 1, when the developing unit 120 is inserted into the image forming apparatus main body 101, the developing unit 120 is inclined downward (apparatus) along a guide rail (not shown) provided on the image forming apparatus main body 101 side. Move inward). Then, when the developing unit 120 approaches a prescribed position where it abuts on the drum unit 110, an engaging convex portion 124 provided on the developing unit 120 is provided on the image forming apparatus main body 101 side as shown in FIG. It will be in the state mounted on the press member 132 of the buffer means 130. FIG. At this time, the engaged inclined surface 132A of the pressing member 132 and the engaging inclined surface 124A of the engaging convex portion 124 contact and engage.

  When the developing unit 120 is advanced in the insertion direction, the pressing member 132 moves in the insertion direction together with the engaging convex portion 124. At this time, since the first spring portion 131 is stretched, the reaction force of the first spring portion 131 is transmitted to the developing unit 120 in the direction opposite to the insertion direction. For this reason, the movement of the developing unit 120 in the insertion direction can be decelerated or stopped.

  Therefore, the developing sleeve 122 of the developing unit 120 can be prevented from abutting against the photosensitive drum 111 of the drum unit 110 at an excessive speed. For this reason, damage to the photosensitive drum 111 and the like can be prevented. Then, when the developing unit 120 is moved in the insertion direction, the second spring portion 133 of the buffer means 130 is compressed, the engaging slope 124A gets over the engaged slope 132A, and the slide slope 124C is the descending slope of the pressing member 132. It descends while sliding 132B. As a result, the developing unit 120 contacts the drum unit 110 and is disposed at a predetermined position. As shown in FIGS. 2 and 4, the tip of the pressing member 132 causes the pressed surface 124 </ b> D of the engaging convex portion 124 to be the first. It is biased by the repulsive force of one spring part 131 and is held with a predetermined biasing force. At this time, as shown in FIG. 6, the developing sleeve 122 is opposed to the photosensitive drum 111 while holding a predetermined developing gap.

  Further, when the developing unit 120 is removed from the image forming apparatus main body 101, the pressed surface 124D of the engaging convex portion 124 is only in contact with the tip end portion of the pressing member 132, and therefore the developing unit 120 is lifted up. The holding state can be easily released only by this.

As described above, in this embodiment, immediately before the developing unit 120 comes into contact with the drum unit 110, the insertion speed of the developing unit 120 can be reduced or reduced to zero to reduce the impact force. Therefore, the relaxation of the impact force can prevent the toner from blowing out from the developing unit.
[Second Embodiment]
Next, the configuration of the buffer means 130 of the second embodiment will be described with reference to FIGS.

  FIG. 5 is a state diagram when the drum unit 110 and the developing unit 120 are separate components and the developing unit 120 is inserted into the drum unit 110. The developing unit 120 is provided with a toner container 121 at the rear in the insertion direction. In the image forming apparatus main body 101, a contact wall 103 is erected from below the arrangement space of the developing unit 120. The buffer unit 130 has a telescopic damper 125 provided at the front lower portion in the insertion direction of the developing unit 120. As shown in FIG. 6, the damper 125 has a cylinder part 125a and a rod part 125b using pneumatic pressure or hydraulic pressure. Two dampers 125 are provided on both the left and right sides of the developing unit 120 in the sheet passing width direction and at positions outside the sheet passing area so as not to affect the sheet conveyance. In the damper 125, a rod portion 125b is attached to the front wall surface 120a of the developing unit 120, and the cylinder portion 125a is movable in the direction of the arrow in the drawing with respect to the rod portion 125b.

  When the developing unit 120 is inserted into the image forming apparatus main body 101, the cylinder portion 125 a comes into contact with the contact wall 103 before the developing unit 120 is inserted into the specified position. At the time of this contact, a repulsive force in the direction opposite to the insertion direction is transmitted to the cylinder portion 125a, and the developing unit 120 is decelerated and stops at the specified position. Thus, the impact force on the developing unit 120 is reduced by the damper 125.

  Further, the developing unit 120 receives a resistance force (repulsive force) from the damper 125 at the time of insertion, but this resistance force disappears when it is finally inserted into a specified position. The damper 125 is configured such that when the rod portion 125b enters and exits the cylinder portion 125a, a piston (not shown) fixed to the tip of the rod portion 125b restricts the fluid (gas or oil) in the cylinder portion 125a. Resistive force accompanying fluid restriction is applied to the rod portion 125b. Therefore, when the developing unit 120 is set at a predetermined position in the image forming apparatus main body 101 and the movement of the developing unit 120 is stopped, the damper 125 does not generate a resistance force due to the restriction of the fluid. It is also conceivable that a spring is disposed in place of the damper 125 and the impact when the developing unit 120 is inserted is mitigated by the elastic force of the spring. However, in this case, there is a possibility that the elastic force of the compressed spring acts in a direction in which the developing unit 120 is separated from the drum unit 110, and the developing unit 120 is displaced from the normal position. However, according to the present embodiment, the force by the damper 125 does not act in the stopped state, so there is no concern. Further, no pressure release mechanism is required.

  In this embodiment, the case where the damper 125 is provided on the developing unit 120 side and the contact wall 103 is provided on the image forming apparatus main body 101 side has been described. However, the damper 125 is provided on the image forming apparatus main body 101 side to perform development. A contact wall 103 may be provided on the unit 120 side. Further, when the damper 125 is provided on the developing unit 120 side as in the present embodiment, the damper 125 is also exchanged together with the developing unit 120 as a replacement when the toner is replenished, but the developing unit 120 and the toner storage container 121 are also replaced. May be configured separately so that only the toner container 121 can be replaced. As a result, the number of replacement parts does not increase.

  In the above description, the telescopic damper 125 using hydraulic pressure or air pressure is used as the buffer member. However, the present invention is not limited to this, and a rotary oil damper 126 described later may be used instead of the telescopic damper.

  As shown in FIG. 7, the oil damper 126 includes a main body case 129 attached to the image forming apparatus main body 101 side and a cylindrical body 127 rotatably supported by the main body case 129. A gear 127 a is integrally attached to the cylindrical body 127. Further, the main body case 129 is provided with a mechanism (not shown) for applying a viscous resistance force of oil such as grease to the rotation of the cylindrical body 127. Further, a rack 128 is provided on the developing unit 120 side so as to mesh with the gear 127a. When the developing unit 120 is inserted into the image forming apparatus main body 101 in the direction of the arrow, the rack 128 is engaged with the gear 127 a of the oil damper 126 before the developing unit 120 reaches the specified position. Then, a viscous resistance force in the direction opposite to the insertion direction acts on the gear 127a, and the speed at which the developing unit 120 is inserted into the image forming apparatus main body 101 is reduced by this viscous resistance force. As a result, the impact when the developing unit 120 is set at a predetermined position in the image forming apparatus main body 101 can be reduced. When the developing unit 120 is finally inserted into the specified position, the rotation of the gear 127a is also stopped, and this viscous resistance is lost.

  In this embodiment, the case where the rack 128 is provided on the developing unit 120 side and the oil damper 126 is provided on the image forming apparatus main body 101 side has been described. However, the rack 128 is provided on the image forming apparatus main body 101 side and the developing unit is provided. An oil damper 126 may be provided on the 120 side.

  FIG. 8 is a state diagram when the process cartridge 140 in which the drum unit 110 and the developing unit 120 are integrated is inserted into the image forming apparatus main body 101. Also in this case, the contact wall 103 is erected on the image forming apparatus main body 101 from below the arrangement space of the process cartridge 140 (below the developing sleeve 122 in the process cartridge 140). In addition, a telescopic damper 125 is attached to a substantially central lower part (below the developing sleeve 122) in the insertion direction of the process cartridge 140.

  The damper 125 has the same configuration as described above, and includes a cylinder portion 125a and a rod portion 125b. Two such dampers 125 are provided on the left and right sides of the process cartridge 140 in the sheet passing width direction. When the process cartridge 140 is inserted into the image forming apparatus main body 101, the cylinder portion 125 a comes into contact with the contact wall 103 before the process cartridge 140 is inserted into the specified position. At the time of this contact, a repulsive force in the direction opposite to the insertion direction is propagated to the cylinder part 125a, decelerated and stopped at the specified position. Thus, the impact force on the process cartridge 140 is reduced by the damper 125.

  In this embodiment, the damper 125 is provided on the process cartridge 140 side and the contact wall 103 is provided on the image forming apparatus main body 101 side. However, the damper 125 is provided on the image forming apparatus main body 101 side, and the process is performed. A contact wall 103 may be provided on the cartridge 140 side. Further, the telescopic damper 125 is used. However, the present invention is not limited to this, and a rotary oil damper 126 may be used.

  Next, the operation and operation of the image forming apparatus 100 will be briefly described.

  As shown in FIG. 5, when the drum unit 110 and the developing unit 120 are separate from each other, the image forming apparatus 100 according to the second embodiment has the developing unit 120 when the developing unit 120 is inserted into the image forming apparatus main body 101. , The damper 125 provided in the developing unit 120 comes into contact with the contact wall 103 erected from the image forming apparatus main body 101 side. At the time of this contact, a repulsive force in the direction opposite to the insertion direction is transmitted to the damper 125, and the developing unit 120 is decelerated and stops at the specified position. Thus, the impact force on the developing unit 120 is reduced by the damper 125.

  Accordingly, it is possible to prevent the developing sleeve 122 in the developing unit 120 from striking the photosensitive drum 111 at an excessive speed and receiving a large impact, thereby damaging the photosensitive drum 111 or causing the toner from the developing unit 120 to fall. It is possible to prevent blowing out. Further, the developing sleeve 122 is maintained while maintaining a predetermined developing gap with respect to the photosensitive drum 111.

  Also, as shown in FIG. 8, when the process cartridge 140 is inserted into the image forming apparatus main body 101, the damper 125 provided on the process cartridge 140 side is positioned before the process cartridge 140 is inserted into the specified position. It abuts against the abutment wall 103 erected from the forming apparatus main body 101 side. At the time of this contact, a repulsive force in the direction opposite to the insertion direction is transmitted to the damper 125, the process cartridge 140 is decelerated and stopped at the specified position, and the impact force on the process cartridge 140 is alleviated.

  Therefore, according to the second embodiment, even when the process cartridge 140 is inserted at an excessive speed, it does not receive a large impact force. For this reason, there is no possibility that an impression may be generated in the toner layer of the developing sleeve 122 due to the impact, thereby causing an image defect. Further, since the impact on the process cartridge 140 is reduced, there is no possibility that the gear for driving the photosensitive drum 111 and the drive gear on the image forming apparatus main body 101 side are damaged.

(Other examples)
It should not be understood that the above description and drawings, which form part of the disclosure of the embodiments of the present invention, limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the buffer means 130 is configured to include two spring portions. However, as long as it has elasticity by expanding and contracting in the insertion direction and the vertical direction, rubber or a resin that performs elastic deformation, Of course, this can be realized by using other spring means.

  The present invention can be used in the field of manufacturing image forming apparatuses such as copiers, facsimiles, printers, and multifunction machines having both functions.

1 is a perspective view showing a main part of an image forming apparatus according to a first embodiment of the present invention. 1 is an explanatory cross-sectional view showing a main part of an image forming apparatus according to a first embodiment of the present invention. It is an expanded sectional view showing a buffer means and an engagement convex part concerning the 1st example of the present invention. FIG. 3 is a perspective view of a main part showing a state in which the developing unit in the image forming apparatus according to the first exemplary embodiment of the present invention is viewed from a direction opposite to the insertion direction. FIG. 6 is a cross-sectional side view illustrating a main part of an image forming apparatus according to a second embodiment. It is a principal part perspective view of the attachment state of the buffer means in a 2nd Example. It is a figure which shows schematic structure of an oil damper. FIG. 3 is a cross-sectional side view of a state in which a process cartridge is inserted into the image forming apparatus. It is principal part sectional drawing which shows the conventional image forming apparatus. FIG. 5 is a perspective view showing a contact state between a photosensitive drum and a developing sleeve. FIG. 6 is a diagram illustrating a conventional example in a state where a process cartridge is inserted into an image forming apparatus. FIG. 7 is a diagram illustrating a conventional example when a process cartridge is taken out from an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 101 ... Image forming apparatus main body, 103 ... Contact wall (contact part), 110 ... Drum unit, 111 ... Photosensitive drum, 120 ... Developing unit, 122 ... Developing sleeve , 124... Engaging convex portion, 124 A... Engaging slope, 124 C... Sliding slope, 125 .. damper (damper device), 126... Oil damper, 130. 132 …… Pressing member, 132A .. Engagement slope, 132B .. Lowering slope, 132C .... Slide wall part, 133 ... Second spring part, 140 .... Process cartridge (coupling unit)

Claims (6)

An image forming apparatus in which a drum unit having a photosensitive drum and a developing unit having a developing sleeve are detachably provided on the main body of the image forming apparatus,
An image forming apparatus comprising: a buffering means for propagating a repulsive force in a direction opposite to a direction in which the developing unit is inserted with respect to a developing unit inserted into the image forming apparatus main body. The buffer means has a pressing portion at a free end of a first spring portion that expands and contracts in the insertion direction below the direction opposite to the insertion direction of the arrangement space of the developing unit in the image forming apparatus main body. A base end is fixed to the image forming apparatus main body, a free end is fixed to a lower portion of the pressing portion, and a second spring portion that expands and contracts in the vertical direction is provided below the pressing portion. An engaged slope is formed on the upper part of the pressing part,
On the lower side opposite to the direction in which the developing unit is inserted, an engaging slope that contacts the engaged slope of the pressing portion at a position before the developing unit is inserted to a specified position is formed.
2. The setting according to claim 1, wherein the first spring portion is stretched along with the insertion of the developing unit so as to generate a reaction force in the developing unit in a direction opposite to the insertion direction. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the first spring portion and the second spring portion are coil springs.   The buffer includes a damper device provided on at least one of the image forming apparatus main body and the developing unit, and when the developing unit is inserted into the image forming apparatus main body, the developing unit is inserted into a specified position. The damper device is brought into contact with a contact portion formed on at least one of the developing unit and the image forming apparatus main body, and propagates a repulsive force on the side opposite to the insertion direction to the developing unit. The image forming apparatus according to claim 1, wherein: In an image forming apparatus in which a coupling unit formed by detachably coupling a drum unit having a photosensitive drum and a developing unit joined to the drum unit is inserted into the image forming apparatus main body.
When the coupling unit is inserted into the image forming apparatus main body, buffer means for propagating a repulsive force opposite to the insertion direction to the coupling unit is provided in at least one of the image forming apparatus main body and the coupling unit. An image forming apparatus. The buffer includes a damper device provided on at least one of the image forming apparatus main body and the coupling unit, and the coupling unit is inserted into a predetermined position when the coupling unit is inserted into the image forming apparatus main body. The damper device abuts against a contact portion formed on at least one of the coupling unit and the main body of the image forming apparatus and transmits a repulsive force opposite to the insertion direction to the coupling unit. The image forming apparatus according to claim 5.

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