JP5899709B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a separating member that separates a developing roller from a photoreceptor.

  2. Description of the Related Art Conventionally, a developing unit that has a frame that supports the photosensitive drum, a developing roller that supplies toner to the photosensitive drum and is detachable from the frame, a pressing member that presses the developing unit toward the photosensitive drum, and the photosensitive drum An image forming apparatus is known that includes a separating member that presses the developing unit against the pressing force of the pressing member in order to separate the developing roller from the toner (see Patent Document 1). In this technique, the developing roller is pressed against the photosensitive drum with a predetermined nip pressure by the pressing force of the pressing member, and the developing unit is held between the photosensitive drum and the pressing member.

JP 2009-210631 A

  By the way, the above-described configuration has a problem that the nip pressure between the photosensitive drum and the developing roller increases when the pressing force of the pressing member is increased so that the developing unit does not wobble between the photosensitive drum and the pressing member. It was. On the other hand, the inventor of the present application presses the pressing force adjusting member provided movably on the developing unit toward the photosensitive drum, and presses the developing unit toward the pressing member by the reaction force, thereby pressing the photosensitive drum against the photosensitive drum. It is considered to adopt a structure in which the nip pressure is kept constant while increasing the clamping force between the members.

  Specifically, as the pressing force adjusting member, a structure is considered that moves between a position protruding from the developing roller toward the photosensitive drum side and a position flush with the surface of the developing roller. However, in this structure, if the pressing force adjusting member remains in contact with the photosensitive drum when the developing roller is separated from the photosensitive drum by the separating member, the developing roller is brought into contact with the photosensitive drum again from the separated state. The developing unit may not move smoothly due to the pressing force acting against the pressing member of the pressing force adjusting member. If the developing unit does not move smoothly in this way and tilts in the apparatus, the developing roller is not pressed against the photosensitive drum in a balanced manner, and white spots (a phenomenon in which part of the toner on the developing roller does not transfer to the photosensitive drum). ) Occurs.

  SUMMARY An advantage of some aspects of the invention is that, in an image forming apparatus including a pressing force adjusting member and a separating member, a developing unit is smoothly moved to suppress white spots.

In order to solve the above-described problems, an image forming apparatus according to the present invention includes a photosensitive frame that supports a photosensitive member, a developing unit that includes a developing frame that supports a developing roller, and presses the developing roller against the photosensitive member. A pressing member that presses the developing unit, and a pressing force applied by the pressing member by being in contact with a contacted member provided on one of the photosensitive frame and the developing frame and provided on the other frame. A pressing force adjusting member that presses the developing unit against the pressing force of the pressing member with a pressing force smaller than the pressing member, and the developing roller is separated from the photoconductor against the pressing force of the pressing member. A separating member acting on the developing unit.
The separating member and the pressing force adjusting member are configured such that when the separating member separates the developing roller from the photosensitive member, the moving amount of the developing roller relative to the photosensitive member is greater than the moving amount of the pressing force adjusting member. Is configured to be larger.

  According to this configuration, even if the pressing force adjusting member moves when the developing roller is separated by the separating member, the moving amount of the developing roller is larger than the moving amount of the pressing force adjusting member. It can be reliably separated from the contact member. For this reason, when the developing unit starts to return from the separated state to the contact state, the movement of the developing unit is not hindered by the pressing force acting against the pressing member of the pressing force adjusting member. The roller can be pressed against the photoconductor in a balanced manner, and as a result, white spots can be suppressed.

  In the above configuration, it is desirable that the pressing force adjusting member moves in the same direction as the moving direction of the developing roller.

  According to this, since the moving direction of the pressing force adjusting member and the developing roller is the same, the development for separating the pressing force adjusting member from the contacted member as compared with the structure in which the moving direction of the pressing force adjusting member and the developing roller is different. The amount of movement of the roller can be reduced.

  Further, in the above-described configuration, the contacted member is the photosensitive member, and the pressing force adjusting member is in contact with an outer peripheral surface of the photosensitive member, and a contact member provided movably on the developing frame; It is desirable to provide an urging member that is disposed between the contact member and the developing roller or the developing frame and urges the developing roller against the pressing force of the pressing member.

  According to this, since the shape of the contact member in contact with the photosensitive member can be freely determined (for example, the same as the outer peripheral shape of the developing roller), the photosensitive member can be made smoother than the mode in which the biasing member is in direct contact with the photosensitive member. It can be rotated. In addition, when the contacted member is a photosensitive member, the pressing force adjusting member directly contacts the photosensitive member as compared with the case where a member other than the photosensitive member is used as the contacted portion. The pressure can be adjusted with high accuracy.

  In the above-described configuration, the developing frame is provided with a bearing member that rotatably supports the rotation shaft of the developing roller, and the biasing member is disposed between the contact member and the bearing member. desirable.

  According to this, it is possible to suppress wear of the urging member due to sliding contact with the rotation shaft of the developing roller, as compared with a mode in which the urging member directly presses the rotation shaft of the developing roller.

  In the above-described configuration, it is preferable that the contact member protrudes radially outward from the developing roller in a state before the developing frame is assembled to the photosensitive frame.

  According to this, the stroke of the contact member can be increased compared to the configuration in which the contact member is flush with the developing roller in a state in which the developing frame is removed from the photosensitive member frame. The pressing force generated from the pressing force adjusting member can be stabilized.

  In the above-described configuration, the contact member has a hole or a groove with which the rotation shaft of the developing roller is engaged, and the hole or the groove is in contact with the rotation shaft of the developing roller, and the contact member It is desirable to be formed so as to extend along the moving direction.

  According to this, when the contact member moves, the inner surface of the hole or the groove is always supported by the rotating shaft of the developing roller, so that the contact member can be moved stably.

  In the above-described configuration, it is preferable that the contact member is rotatably supported by the developing frame.

  According to this, the contact member is operated more smoothly than a configuration in which the contact member is slid in a linear direction (a structure in which the guide surface that guides the contact member is small, and the contact member is inclined and easily caught on the guide surface). be able to.

  In the above-described configuration, it is desirable that the pressing force adjusting member is provided at both ends in the axial direction of the developing roller.

  According to this, the pressing force of the developing roller against the photosensitive member can be optimized in a balanced manner in the axial direction.

  In the above-described configuration, it is preferable that the pressing member is provided on both ends of the photosensitive frame in the axial direction of the developing roller.

  According to this, it is possible to prevent unevenness of the pressing force of the developing roller in the axial direction.

  According to the present invention, in an image forming apparatus including a pressing force adjusting member and a separation member, it is possible to smoothly move the developing unit and suppress white spots.

1 is an explanatory diagram illustrating an overall configuration of a color printer according to an embodiment. FIG. It is a perspective view which shows the detail of the structure of a process cartridge. FIG. 4 is a side view illustrating a photosensitive drum, a developing cartridge, a pressing member, and a separation member. It is a disassembled perspective view which shows a pressing force adjustment member, a bearing member, and a developing roller. It is a perspective view which shows the state which assembled | attached the pressing force adjustment member, the bearing member, and the developing roller. It is explanatory drawing which shows the relationship between a photosensitive drum, a rocking | swiveling member, and a developing roller, the figure which shows a state when a rocking | swiveling member is separated from the photosensitive drum, and a rocking | swiveling member and a developing roller are made to contact a photosensitive drum. It is a figure (b) showing a state at the time. It is a perspective view which shows the deformation | transformation state of the coil spring of a pressing force adjustment member, (a) which shows a state when a rocking | swiveling member is separated from the photosensitive drum, and when a rocking | fluctuating member and a developing roller are made to contact a photosensitive drum It is a figure (b) which shows the state of.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, the overall configuration of the color printer (image forming apparatus) will be described, and then the details of the features of the present invention will be described.

  In the following description, the direction will be described based on the user when using the color printer. That is, in FIG. 1, the right side toward the paper surface is “front side”, the left side toward the paper surface is “rear side”, the back side toward the paper surface is “right side”, and the front side toward the paper surface is “left side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, the color printer 1 includes an image forming unit in which a paper feeding unit 20 that supplies paper P, an image forming unit 30 that forms an image on the fed paper P, and an image are formed. And a paper discharge section 90 for discharging the paper P.

  The paper feed unit 20 includes a paper feed tray 21 that accommodates the paper P and a paper transport device 22 that transports the paper P from the paper feed tray 21 to the image forming unit 30.

  The image forming unit 30 includes a scanner unit 40, a process unit 50, a transfer unit 70, and a fixing unit 80.

  The scanner unit 40 is provided in an upper part of the apparatus main body 10 and includes a laser light emitting unit, a polygon mirror, a lens, a reflecting mirror, and the like (not shown). In the scanner unit 40, the laser beam is irradiated on the surface of each photosensitive drum 61 of the process unit 50 by high-speed scanning through a path indicated by a two-dot chain line in the drawing.

  The process unit 50 can be attached to and detached from the apparatus main body 10 through an opening 10 </ b> A formed by opening the front cover 11 disposed on the front surface of the apparatus main body 10. The process unit 50 includes a drawer 60 and four developing cartridges 100 as an example of a developing unit detachably provided on the drawer 60.

  The drawer 60 includes four photosensitive drums 61 as an example of a photosensitive member, and also includes a known charger (not shown).

  The developing cartridge 100 is rotatably provided with a developing roller 110 that contacts the photosensitive drum 61 and supplies toner, and is appropriately provided with a known toner storage chamber, a supply roller, and the like.

  The transfer unit 70 is provided between the paper feeding unit 20 and the process unit 50, and includes a driving roller 71, a driven roller 72, a conveyance belt 73, and four transfer rollers 74.

  The driving roller 71 and the driven roller 72 are arranged in parallel in a spaced manner in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyor belt 73 is in contact with each photosensitive drum 61. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 between the photosensitive drums 61 are arranged inside the conveyor belt 73 so as to face the photosensitive drums 61. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

  The fixing unit 80 is disposed on the rear side of the process unit 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 61 is uniformly charged by a charger and then exposed by the scanner unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 61. Thereafter, the toner in the developing cartridge 100 is supplied to the electrostatic latent image on the photosensitive drum 61 by the developing roller 110, so that the toner image is carried on the photosensitive drum 61.

  Next, the paper P supplied on the conveyance belt 73 passes between each photosensitive drum 61 and each transfer roller 74, so that the toner image formed on each photosensitive drum 61 is transferred onto the paper P. The Then, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 includes a plurality of transport rollers 91 that transport the paper P. The sheet P on which the toner image has been transferred and heat-fixed is transported by the transport roller 91 and discharged outside the apparatus main body 10.

<Details of the structure around the process unit 50>
Next, the structure around the process unit 50 will be described in detail.
The process unit 50 includes the drawer 60 and the developing cartridge 100 described above, and a separating member 400 for separating the developing cartridge 100 (the developing roller 110) in the drawer 60 from the photosensitive drum 61.

  The drawer 60 mainly includes a photosensitive frame 62 that rotatably supports four photosensitive drums 61 arranged side by side, and a pressing member 63 that biases the developing cartridge 100 toward the photosensitive drum 61. Yes.

  The photoconductor frame 62 is formed in a rectangular tube shape that opens upward and downward, and supports the photoconductive drums 61 at the lower portions of the left and right side walls. Further, a handle portion 62 </ b> A that protrudes forward is provided on the front wall of the photoconductor frame 62. As a result, the user can grasp the handle 62A and pull the drawer 60 forward.

  As shown in FIGS. 2 and 3, the pressing member 63 is a member that presses the developing cartridge 100 rearward and obliquely downward so that the developing roller 110 is pressed against the photosensitive drum 61. One is provided on each of the left and right sides in the vicinity of the portion (both ends in the axial direction of the developing roller 110, specifically, positions symmetrical with respect to the center in the axial direction). As a result, the developing cartridge 100 can be pressed in a balanced manner on the left and right, so that the pressing force of the developing roller 110 against the photosensitive drum 61 can be made uniform in the left-right direction.

  The pair of left and right pressing members 63 are provided in pairs corresponding to the developing cartridges 100 arranged in the front-rear direction. Since each pair of pressing members 63 has the same structure, in the following description, a pair of pressing members 63 corresponding to one developing cartridge 100 will be described. Moreover, since a pair of press member 63 becomes a left-right symmetric structure, in the following description, only one of right and left is demonstrated and the other description shall be abbreviate | omitted.

  The pressing member 63 includes a lock member 631 that is swingably supported by the photoconductor frame 62, and a torsion spring 632 that biases the lock member 631 toward the photosensitive drum 61 (developing cartridge 100). Then, the lock member 631 biased by the torsion spring 632 presses the engagement protrusion 121 formed on the developing frame 120 of the developing cartridge 100 so that the developing cartridge 100 is pressed toward the photosensitive drum 61. It has become.

  On the other hand, the end of the developing cartridge 100 on the side of the photosensitive drum 61 abuts on the photosensitive drum 61 as an example of a member to be abutted from the upper front side (upstream in the pressing direction of the pressing member 63). A pressing force adjusting member 200 that biases the drum 61 obliquely downward (in the pressing direction) is provided. The pressing force adjusting member 200 is configured to press the developing cartridge 100 against the pressing force of the pressing member 63 with a pressing force smaller than the pressing force of the pressing member 63.

As a result, even if the pressing force of the pressing member 63 is increased, the increased pressing force can be offset by the pressing force of the pressing force adjusting member 200. Therefore, the pressing force of the developing roller 110 against the photosensitive drum 61 is set appropriately. It is possible to keep it at a certain value. Further, since the developing cartridge 100 can be firmly sandwiched between the pressing member 63 and the pressing force adjusting member 200, the developing cartridge 100 can be firmly held by the drawer 60.
The pressing force of the pressing member 63 and the pressing force adjusting member 200 arranged on the left and right sides is adjusted according to the position of the center of gravity of the developing cartridge 100 and may be changed on the left and right.

  Although not shown, the developing cartridge 100 is guided to the position shown in FIG. 3 (between the photosensitive drum 61 and the pressing member 63) on the left and right side walls of the photoconductor frame 62, and in the posture shown in FIG. A well-known guide groove or guide rib to be held is formed. The developing cartridge 100 held by the guide groove or the like is firmly held by the photoconductor frame 62 by being sandwiched between the pressing member 63 and the photosensitive drum 61 (pressing force adjusting member 200). ing.

  One pressing force adjusting member 200 is provided at each of the left and right end portions of the developing roller 110 (both end portions in the axial direction, specifically, positions symmetrical with respect to the center in the axial direction). As a result, the pressing force of the developing roller 110 against the photosensitive drum 61 can be optimized with a good balance in the axial direction.

  A pair of left and right pressing force adjusting members 200 is provided for each developing cartridge 100. Since each pair of pressing force adjusting members 200 has the same structure, in the following description, the pair of pressing force adjusting members 200 provided in one developing cartridge 100 will be described. Further, since the pair of left and right pressing force adjusting members 200 have a bilaterally symmetric structure, in the following description, only one of the left and right will be described and the description of the other will be omitted.

  As shown in FIGS. 4 and 5, the pressing force adjustment member 200 includes a swing member 210 as an example of a contact member and a coil spring 220 as an example of an urging member.

  The swing member 210 has a main body 230 formed in a substantially fan shape that expands downward, and a contact portion 240 that contacts the outer peripheral surface of the photosensitive drum 61.

  The main body 230 has a circular engagement hole 231 formed in the upper portion thereof, and a long hole 232 extending in an arc shape in the lower portion thereof. A rotation shaft 310 provided in a bearing member 300 (described later) enters and engages with the engagement hole 231, so that the main body 230 can swing around the rotation shaft 310. It has become.

  Specifically, the main body 230 is rotatably supported by the rotation shaft 310 so that a lower end portion thereof can swing (movable) in the pressing direction of the pressing member 63. In other words, the main body 230 is rotatably supported by the developing frame 120 via the bearing member 300.

  Here, the bearing member 300 rotatably supports the rotating shaft 111 of the developing roller 110 and is fixed to the developing frame 120 (see FIG. 3). In other words, the developing roller 110 and the main body 230 are supported by the developing frame 120 via the bearing member 300.

  The long hole 232 is a hole through which the rotation shaft 111 of the developing roller 110 is inserted. As shown in FIGS. 6A and 6B, the long hole 232 is formed with a width substantially the same as the diameter of the rotation shaft 111. The rotary shaft 111 is brought into contact. And this long hole 232 is formed in the circular arc shape centering on the rotating shaft 310 of the bearing member 300 so that it may extend along the rocking | fluctuation direction of the main-body part 230. As shown in FIG. Thereby, when the swinging member 210 swings, the inner surface of the long hole 232 is always supported by the rotating shaft 111 of the developing roller 110, so that the swinging member 210 can be swung stably. ing.

  Further, the end of the long hole 232 opposite to the contact part 240 is opened to the outside by a slit 233 narrower than the long hole 232. As a result, the swinging member 210 can be attached to the rotation shaft 111 of the developing roller 110 from the radial direction, and the swinging member 210 can be assembled after the developing roller 110 is assembled to the developing frame 120. Becomes easy.

  The contact part 240 is formed so as to protrude inward in the left-right direction from the edge of the main body part 230 on the photosensitive drum 61 side, and is movable in the pressing direction of the pressing member 63 as the main body part 230 swings. It has become. The contact portion 240 is formed in a shape that substantially matches the shape of the outer peripheral surface of the developing roller 110 that is pressed against the photosensitive drum 61. Therefore, the pressure applied to the photosensitive drum 61 from the developing roller 110 and the contact portion 240 can be made constant in the axial direction, so that the photosensitive drum 61 can be smoothly rotated.

  As shown in FIGS. 7A and 7B, the coil spring 220 has a natural length between the contact portion 240 of the swing member 210 and the planar ground surface 320 formed on the bearing member 300, or Arranged in a contracted state from the natural length. In other words, the biasing force of the coil spring 220 is received by the swing member 210 and also by the developing frame 120 via the bearing member 300, so that the coil spring 220 is mechanically viewed from the swing member 210 and the developing frame 120. It is provided between. The coil spring 220 only needs to be fixed to one of the contact portion 240 and the ground plane 320.

  The coil spring 220 and the contact portion 240 and the grounding surface 320 in the mounted state (the state in FIG. 7B) than in the state before the developing cartridge 100 is mounted in the drawer 60 (the state in FIG. 7A). , The developing cartridge 100 is biased against the pressing force of the pressing member 63. Here, in FIG. 7, the coil spring 220 is illustrated in a simplified manner, and expansion and contraction is expressed by changing the interval between a plurality of lines indicating the coil spring 220.

  Further, the coil spring 220 is mounted with the contact portion 240 in a state where the developing cartridge 100 is removed from the drawer 60 (a state before being assembled to the drawer 60, more specifically, a state where the contact portion 240 is separated from the photosensitive drum 61). It is held at a position moved to the photosensitive drum 61 side from the position at the time. As a result, in a state where the developing cartridge 100 is removed from the drawer 60 or a state where the developing roller 110 is separated from the photosensitive drum 61 by a spacing member 400 described later (see FIG. 6A), the contact portion 240 is moved to the developing roller. It protrudes to the photosensitive drum 61 side (radially outer side) than 110.

  Thus, the stroke of the contact portion 240 can be increased compared to the configuration in which the contact portion is flush with the developing roller in a state where the developing cartridge 100 is removed from the drawer 60, and therefore, the deformation amount of the coil spring 220 is increased. Thus, the pressing force generated from the pressing force adjusting member 200 can be stabilized.

  As shown in FIGS. 1 and 3, the separating member 400 is a member that acts on the developing cartridge 100 so as to separate the developing roller 110 from the photosensitive drum 61 against the pressing force of the pressing member 63. One separation arm 410 and one separation cam 420 are provided.

  One separation arm 410 is arranged on each side of each developing cartridge 100 in the left-right direction. Specifically, the separating arm 410 is disposed inside the left and right side walls of the photoconductor frame 62 and is rotatably provided on the side walls, so that the upper and lower end portions thereof can swing substantially in the front-rear direction. Yes.

  A protrusion 411 that protrudes inward in the left-right direction is formed at the lower end of the separation arm 410. When the separation arm 410 is swung counterclockwise in the drawing, the protrusion 411 of the separation arm 410 develops. The engaging protrusion 121 provided on the cartridge 100 is pushed forward obliquely upward, and the developing roller 110 is separated from the photosensitive drum 61 along a guide portion (not shown) (see FIG. 6A).

  Specifically, the moving direction of the protruding portion 411 of the separating arm 410 during the swinging is set to the same direction as the moving direction of the contact portion 240 of the pressing force adjusting member 200. Each separation arm 410 is operated by a separation cam 420.

  The separation cam 420 is a long linear motion cam that extends in the front-rear direction (arrangement direction of the plurality of developing rollers 110), and moves rearward so as to move outward from the upper end portion of the separation arm 410 (drawer). The spacing arm 410 is swung counterclockwise by pressing a portion (not shown) projecting toward the outside (60). Specifically, the separation cam 420 is disposed inside the left and right side walls of the apparatus main body 10 and is supported on each side wall so as to be movable in the front-rear direction.

  The separation cam 420 has four cam surfaces 421 inclined with respect to the front-rear direction, and each separation arm 410 is pressed by each cam surface 421. Thereby, for example, it is possible to switch between the color mode and the monochrome mode.

  The separation cam 420 is moved in the front-rear direction by a drive mechanism (not shown) provided in the apparatus main body 10. Here, as the drive mechanism, a mechanism constituted by a motor, a gear, or the like, a mechanism for moving the separating cam 420 back and forth in conjunction with opening and closing of the front cover 11, and the like can be employed.

  Then, as shown in FIG. 6A, the separation member 400 and the pressing force adjustment member 200 described above allow the development roller 110 to move away from the photosensitive drum 61 when the separation roller 400 separates the development roller 110 from the photosensitive drum 61. The moving amount L1 is configured to be larger than the moving amount L2 of the pressing force adjusting member 200. That is, the movement amount of the separation cam 420, the rotation amount of the separation arm 410, and the stroke of the pressing force adjusting member 200 are appropriately set so that the movement amounts L1 and L2 have the above-described relationship.

  Thereby, even when the pressing force adjusting member 200 moves closer to the photosensitive drum 61 when the developing roller 110 is separated by the separating member 400, the moving amount L1 of the developing roller 110 is the moving amount of the pressing force adjusting member 200. Since it is larger than L2, the pressing force adjusting member 200 can be reliably separated from the photosensitive drum 61. Therefore, when the developing cartridge 100 starts to return from the separated state shown in FIG. 6A to the contact state shown in FIG. 6B, the movement of the developing cartridge 100 opposes the pressing member 63 of the pressing force adjusting member 200. Since it is not hindered by the acting pressing force, it is possible to smoothly move the developing cartridge 100 against the frictional force with the guide portion and press the developing roller 110 against the photosensitive drum 61 in a balanced manner. It is possible to suppress.

  In the present embodiment, as described above, the movement direction of the protruding portion 411 of the separation arm 410 is set to the same direction as the movement direction of the contact portion 240 of the pressing force adjusting member 200. The developing roller 110 moves in the same direction as the moving direction (the direction separated by the separating member 400). Accordingly, it is possible to reduce the moving amount L1 of the developing roller 110 for separating the pressing force adjusting member 200 from the photosensitive drum 61 as compared with the structure in which the moving directions of the pressing force adjusting member 200 and the developing roller 110 are different. ing.

According to the above, in addition to the effects described above, the following effects can be obtained in the present embodiment.
Since the pressing force adjustment member 200 includes the swing member 210 and the coil spring 220, the shape of the swing member 210 that contacts the photosensitive drum 61 can be freely determined as compared with, for example, a configuration in which the pressing force adjustment member includes only a spring. be able to. As a result, as in the present embodiment, the shape of the contact portion 240 of the swinging member 210 can be made substantially the same as the shape of the outer peripheral surface of the developing roller 110, so that the photosensitive drum 61 can be smoothly rotated. .

  Since the coil spring 220 is disposed between the swinging member 210 and the bearing member 300, the coil spring 220 is less worn due to sliding contact with the rotation shaft 111 of the developing roller 110 than in the case where the coil spring is in contact with the rotation shaft of the developing roller 110. Can be suppressed.

  Since the swing member 210 (contact member) is provided so as to be rotatable with respect to the developing cartridge 100, the contact member is slid in a linear direction (the guide surface for guiding the contact member is small, and the contact member is tilted during sliding). Thus, the swinging member 210 can be operated more smoothly than a structure that is easily caught on the guide surface.

  Since the developing cartridge 100 is pressed at the four positions of the pair of left and right pressing members 63 and the pair of left and right pressing force adjusting members 200 arranged symmetrically, the developing cartridge 100 can be pressed in a balanced manner.

In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.
In the above embodiment, the photosensitive drum 61 is exemplified as the contacted portion. However, the present invention is not limited to this, and the contacted portion may be another member provided integrally or separately on the photosensitive frame, for example, a photosensitive member. It may be a bearing member that rotatably supports the drum. As will be described later, when the pressing force adjusting member is provided on the photosensitive member frame, the contacted portion is a bearing that rotatably supports another member, for example, a developing roller, which is provided integrally or separately with the developing frame. It may be a member.

  However, when the contacted portion is the photosensitive drum 61 as in the above-described embodiment, the pressing force adjusting member 200 directly contacts the photosensitive drum 61, so that the pressing force of the developing roller 110 against the photosensitive drum 61 can be accurately set. Can be adjusted.

  In the above-described embodiment, the developing cartridge 100 integrally including the developing roller 110 and the toner storage chamber is illustrated as an example of the developing unit, but the present invention is not limited to this. For example, when a toner cartridge having a toner storage chamber and a developing device having a developing roller are configured separately, the developing unit may be a developing device.

  In the above embodiment, the developing cartridge 100 can be attached to and detached from the photoconductor frame 62. However, the present invention is not limited to this, and the developing unit cannot be removed from the photoconductor frame unless a tool such as a driver is used. The present invention may be applied to a structure.

  In the above embodiment, the photosensitive drum 61 is illustrated as an example of the photosensitive member, but the present invention is not limited to this, and may be a belt-shaped photosensitive member, for example.

  In the above embodiment, the pressing member and the pressing force adjusting member are constituted by two parts, but the present invention is not limited to this, and may be constituted by only a coil spring or a leaf spring, for example. In addition, the pressing member may be provided in the developing unit contrary to the above embodiment, and the pressing force adjusting member may be provided in the photoconductor frame contrary to the above embodiment.

  In the above-described embodiment, one pressing member is provided on each end of the developing roller in the axial direction. However, the present invention is not limited to this, and for example, only one pressing member may be provided in the central portion in the axial direction. Three or more may be provided with good balance (so as to be symmetric with respect to the center in the axial direction). Further, the position and number of the pressing force adjusting members are not limited to the above-described embodiment, and for example, only one may be provided on one end side in the axial direction, or two may be provided on both end sides in the axial direction.

  In the above-described embodiment, the separation member 400 includes the separation arm 410 and the separation cam 420. However, the present invention is not limited to this, and, for example, linearly moves in the pressing direction of the pressing member to press the developing unit. The spacing member may be constituted by a slide member or the like.

  In the embodiment, the swingable swinging member 210 is illustrated as an example of the contact member. However, the present invention is not limited to this, and the contact member may be, for example, a linearly movable slide member. Good. In the above embodiment, the contact member is supported by the bearing member. However, the present invention is not limited to this, and may be directly supported by the developing frame, for example.

  In the embodiment, the coil spring 220 is illustrated as an example of the urging member, but the present invention is not limited to this, and may be, for example, a torsion spring or a leaf spring. In the above embodiment, the urging member is disposed between the contact member and the bearing member (developing frame). However, the present invention is not limited to this, for example, between the contact member and the developing roller (rotating shaft). You may arrange in.

  In the above-described embodiment, the arcuate elongated hole 232 that penetrates the swinging member 210 in the axial direction of the developing roller 110 is provided, and the rotating shaft 111 of the developing roller 110 is passed through the elongated hole 232. For example, an arcuate groove (same shape as the long hole 232 in the above embodiment) that does not penetrate in the axial direction is provided in the swing member 210, and the end of the rotating shaft of the developing roller is engaged with this groove. Also good. Even in this case, since the groove is always supported by the rotation shaft of the developing roller, the rocking member 210 can be rocked stably.

  In the above-described embodiment, the present invention is applied to the color printer 1, but the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as monochrome printers, copiers, and multifunction machines. Good.

DESCRIPTION OF SYMBOLS 1 Color printer 61 Photosensitive drum 62 Photoconductor frame 63 Pressing member 100 Developing cartridge 110 Developing roller 120 Developing frame 200 Pressing force adjusting member 400 Separating member

Claims (7)

A photoreceptor frame for supporting the photoreceptor;
A developing unit that includes a developing frame that supports the developing roller, and a bearing member that is provided on the developing frame and rotatably supports the rotation shaft of the developing roller ;
A pressing member that presses the developing unit so that the developing roller is pressed against the outer peripheral surface of the photoreceptor;
Movably provided in front Symbol developing frame, that abuts on the photosensitive member, with a small pressing force than the pressing force by the pressing member to press against the developing unit to the pressing force of the pressing member A pressing force adjusting member , which is disposed between the contact member and the bearing member, and a contact member that contacts the outer peripheral surface of the photosensitive member and is movably provided on the developing frame; A pressing force adjusting member comprising an urging member that urges against the pressing force of the pressing member ;
A separating member acting on the developing unit so as to separate the developing roller from the photoreceptor against the pressing force of the pressing member,
When the developing roller is separated from the photosensitive member by the separating member, the moving amount of the developing roller with respect to the photosensitive member is larger than the moving amount of the pressing force adjusting member. An image forming apparatus comprising an adjustment member.   The image forming apparatus according to claim 1, wherein the pressing force adjusting member moves in the same direction as a moving direction of the developing roller. The contact member, in a state before the developing frame is assembled to said photosensitive member frame, the image formation according to claim 1 or claim 2, characterized in that projecting radially outward from the developing roller apparatus. The contact member has a hole or groove with which the rotation shaft of the developing roller engages
The hole or the groove, while in contact with the rotation shaft of the developing roller, one of claims 1 to 3, characterized in that it is formed so as to extend along the moving direction of the contact member 1 The image forming apparatus described in the item. The contact member, an image forming apparatus according to any one of claims 1 to 4, characterized in that it is rotatably supported by the developing frame. The pressing force adjusting member is an image forming apparatus according to any one of claims 1 to 5, characterized in that provided at both ends in the axial direction of the developing roller. The pressing member, an image forming apparatus according to any one of claims 1 to 6, characterized in that provided at both end sides in the axial direction of the developing roller of said photosensitive member frame.

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