JP5565484B2 - Process unit and development unit - Google Patents

Description

  The present invention relates to a developing unit that can be attached to and detached from a photosensitive unit, and a process unit that includes the photosensitive unit and the developing unit.

  Conventionally, there has been known a process unit including a photosensitive unit having a photosensitive drum, a developing unit having a developing roller that supplies toner to the photosensitive drum, and a coil spring that presses the developing unit so that the developing roller is pressed against the photosensitive drum. (See Patent Document 1).

  Specifically, in this technique, the photosensitive unit is formed in a box shape that opens upward, a photosensitive drum is provided at one end of the box-shaped photosensitive unit, and a coil spring is provided at the other end. For this reason, when the developing unit is mounted in the photosensitive unit, the developing roller is pressed against the photosensitive drum by a coil spring with a predetermined pressing force, and the developing unit is held between the photosensitive drum and the coil spring. .

JP 2009-180987 A

  However, the above-described technique has a problem that the developing unit is wobbled when a large force is applied to the developing unit attached to the photosensitive unit. To cope with this problem, it is conceivable to firmly hold the developing unit on the photosensitive unit by increasing the biasing force of the coil spring. However, in this case, the pressing force of the developing roller against the photosensitive drum is increased, so that each roller is smooth. There was a risk that it would stop rotating.

  Accordingly, an object of the present invention is to suppress the wobbling of the developing unit while maintaining the pressing force of the developing roller against the photosensitive drum (photosensitive member) at an appropriate value.

  In order to solve the above-mentioned problems, a process unit according to the present invention includes a photosensitive member frame that supports a photosensitive member, a developing frame that supports a developing roller that contacts the photosensitive member, and the developing roller that presses against the photosensitive member. A first pressing member that generates a pressing force, and a second pressing member that generates a pressing force that is smaller than the pressing force of the first pressing member against the pressing force of the first pressing member. It is characterized by.

  The developing unit according to the present invention can be attached to and detached from a photosensitive unit having a photosensitive member on which an electrostatic latent image is formed, and is directed toward the photosensitive member by a first pressing member provided in the photosensitive unit. A developing unit to be pressed, which is a developing roller that contacts the photoconductor to supply the developer, a developing frame that rotatably supports the developing roller, and a pressed portion that is pressed by the first pressing member And a second pressing member that presses the developing unit against the pressing force of the first pressing member with a pressing force smaller than the pressing force of the first pressing member.

  According to the present invention, even if the pressing force of the first pressing member is increased, the pressing force can be offset by the pressing force of the second pressing member, so that the pressing force of the developing roller against the photosensitive member is set to an appropriate value. Can keep. Further, since the developing unit (developing frame or developing roller) can be firmly sandwiched between the first pressing member and the second pressing member, the wobbling of the developing unit can be suppressed.

  According to the present invention, the wobbling of the developing unit can be suppressed while keeping the pressing force of the developing roller against the photosensitive member at an appropriate value.

1 is an explanatory diagram illustrating an overall configuration of a color printer. FIG. It is a perspective view showing details of the structure of the process cartridge according to the present embodiment. FIG. 4 is a side view showing a photosensitive drum, a developing cartridge, and a first pressing member. It is a disassembled perspective view which shows a 2nd press member, a bearing member, and a developing roller. It is a perspective view which shows the state which assembled | attached the 2nd press 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 2nd press member, the figure (a) which shows a state when a rocking | fluctuating 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 with reference to 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 as an example of a photoreceptor unit and four developing cartridges 100 as an example of a developing unit that is 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 as an example of a developer, 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 of the process unit 50>
Next, the structure of the drawer 60 and the developing cartridge 100 constituting the process unit 50 will be described in detail.

  The drawer 60 includes a photosensitive frame 62 that rotatably supports four photosensitive drums 61 arranged side by side, and a first pressing member 63 that urges 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 first pressing member 63 is a member that presses the developing cartridge 100 rearward and downward so that the developing roller 110 is pressed against the photosensitive drum 61. Are provided one on each of the left and right sides in the vicinity of each corner (both ends in the axial direction of the developing roller 110, specifically, symmetrical positions 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.

  A pair of left and right first pressing members 63 are provided in pairs corresponding to the developing cartridges 100 arranged in the front and rear. Since each pair of first pressing members 63 has the same structure, in the following description, the pair of first pressing members 63 corresponding to one developing cartridge 100 will be described. In addition, since the pair of first pressing members 63 has 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.

  The first pressing member 63 includes a lock member 631 that is swingably supported by the photoreceptor 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 an engagement protrusion 121 as an example of a pressed portion formed on the developing frame 120 of the developing cartridge 100, so that the developing cartridge 100 is in the photosensitive drum 61. It comes to be pressed toward

On the other hand, the end of the developing cartridge 100 on the photosensitive drum 61 side contacts the photosensitive drum 61 and resists the pressing force of the first pressing member 63 with a pressing force smaller than the pressing force of the first pressing member 63. Thus, a second pressing member 200 that presses the developing cartridge 100 is provided. As a result, even if the pressing force of the first pressing member 63 is increased, the increased pressing force can be offset by the pressing force of the second pressing member 200, so that the pressing force of the developing roller 110 against the photosensitive drum 61 is increased. Can be maintained at an appropriate value. Further, since the developing cartridge 100 can be firmly sandwiched between the first pressing member 63 and the second pressing member 200, the developing cartridge 100 can be firmly held by the drawer 60.
The pressing force of the first pressing member 63 and the second pressing member 200 arranged on the left and right sides is adjusted by 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 first pressing member 63) on the left and right side walls of the photoconductor frame 62, and also shown in FIG. Known guide grooves, guide ribs, and the like that are held in a posture are 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 first pressing member 63 and the photosensitive drum 61 (second pressing member 200). It has become.

  One second pressing 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 second pressing members 200 is provided for each developing cartridge 100. In addition, since each pair of 2nd press member 200 is comprised by the same structure altogether, in the following description, a pair of 2nd press member 200 provided in one developing cartridge 100 is demonstrated. In addition, since the pair of left and right second pressing 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 second pressing member 200 includes a swinging 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 the lower end portion thereof can swing (movable) in the pressing direction of the first 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. Accordingly, the swing member 210 can be attached to the rotation shaft 111 of the developing roller 110 from the radial direction, and the swing member 210 can be assembled after the development roller 110 is assembled.

  The contact portion 240 is formed so as to protrude inward in the left-right direction from the edge of the main body portion 230 on the photosensitive drum 61 side, and in the pressing direction of the first pressing member 63 as the main body portion 230 swings. It is movable. 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 coil spring 220 has one end supported by the swing member 210 and the other end supported by the developing frame 120 via the bearing member 300, so that the coil spring 220 is provided between the swing member 210 and the developing frame 120. It has been. 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 first 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, as shown in FIG. 6A, when the developing cartridge 100 is removed from the drawer 60, the contact portion 240 protrudes to the photosensitive drum 61 side (radially outward) from the developing roller 110. ing.

  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 second pressing member 200 can be stabilized.

According to the above, the following effects can be obtained in the present embodiment.
By offsetting the increase in the pressing force of the first pressing member 63 with the pressing force of the second pressing member 200, the pressing force of the developing roller 110 against the photosensitive drum 61 can be maintained at an appropriate value. Further, by firmly sandwiching the developing cartridge 100 between the first pressing member 63 and the second pressing member 200, the wobbling of the developing cartridge 100 can be suppressed.

  Since the second pressing 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 second press member is configured only by the 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.

  In a state in which the developing cartridge 100 is removed from the drawer 60, the contact portion 240 protrudes toward the photosensitive drum 61 with respect to the developing roller 110. Therefore, the stroke of the contact portion 240 can be increased and generated from the second pressing member 200. The pressing force can be stabilized.

  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.

  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 second pressing member 200 is provided at both ends of the developing roller 110 in the axial direction, the pressing force of the developing roller 110 against the photosensitive drum 61 can be optimized in a balanced manner in the axial direction.

  Since the first pressing member 63 is provided on both the left and right sides (both sides in the axial direction of the developing roller 110) of the photoconductor frame 62, it is possible to prevent the bias of the pressing force of the developing roller 110 in the axial direction.

  Since the developing cartridge 100 is pressed at the four positions of the pair of left and right first pressing members 63 and the pair of left and right second pressing 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, as an example of the photosensitive unit, the plurality of photosensitive drums 61 are collectively supported and one drawer 60 in which the plurality of developing cartridges 100 can be attached / detached is illustrated, but the present invention is limited to this. is not. For example, the photosensitive unit may have only one photosensitive drum and may be one drum cartridge in which only one developing unit is detachable.

  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 unit can be attached to and detached from the photosensitive unit. However, the present invention is not limited to this, and the developing unit cannot be removed from the photosensitive unit without using a tool such as a screwdriver. The present invention may be applied.

  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 said embodiment, although the 1st press member and the 2nd press member were comprised by 2 components, this invention is not limited to this, For example, you may comprise only with a coil spring and a leaf | plate spring. In addition, the first pressing member may be provided in the developing unit contrary to the above embodiment, and the second pressing member may be provided in the photoconductor unit contrary to the above embodiment.

  In the above-described embodiment, one first pressing member is provided on each end in the axial direction of the developing roller. However, the present invention is not limited to this. For example, only one first pressing member may be provided in the central portion in the axial direction. Three or more may be provided in a balanced manner (so as to be symmetric with respect to the axial center). Moreover, the position and the number of the second pressing members are not limited to the above-described embodiment. 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 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.

50 Process Unit 60 Drawer 61 Photosensitive Drum 62 Photoconductor Frame 63 First Pressing Member 100 Developing Cartridge 110 Developing Roller 120 Developing Frame 200 Second Pressing Member

Claims (1)

A photoreceptor unit having a photoreceptor frame that supports the photoreceptor;
A developing frame for supporting a developing roller in contact with the photoreceptor;
A first pressing member that generates a pressing force so that the developing roller is in pressure contact with the photoreceptor;
A second pressing member that is provided in the photoconductor unit and generates a pressing force that is smaller than the pressing force of the first pressing member against the pressing force of the first pressing member. unit.

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