JP7106300B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile machine, and a multifunction machine having a plurality of these functions.

2. Description of the Related Art In an electrophotographic image forming apparatus, an electrostatic latent image formed on a photosensitive drum serving as an image bearing member is developed into a toner image by a developer carried on a developing sleeve serving as a developer carrying member. Further, as an image forming apparatus, there has been conventionally known a configuration in which a developing device having a developing sleeve is detachably attached to an apparatus main body.

Such an image forming apparatus is required to maintain a constant predetermined gap (SD gap) between the photosensitive drum and the developing sleeve. This is because if the SD gap fluctuates, image defects such as image density unevenness will occur. For this reason, a configuration is conventionally known in which the SD gap is kept constant by bringing the member on the photosensitive drum side and the member on the developing sleeve side into contact with each other. Also, there is known a configuration in which the above-described members are brought into contact with each other by pressing the developing device against the photosensitive drum with a pressure spring as a pressure means.

Further, as a developing device, there is known a configuration in which the developing device can move between a contact position where the gap between the photosensitive drum and the developing sleeve is a predetermined gap and a separated position away from the contact position. In the case of this configuration, the developing device is moved when the developing device is mounted, etc., and the above-described members are brought into contact with each other to form the above-described SD gap.

Further, in order to ensure the SD gap, the member on the photosensitive drum side and the member on the developing sleeve side are brought into contact at two points, and the angle formed by the butting direction (X direction) of the developing sleeve is 90° or more and 180°. A configuration has been proposed in which contact is made at three points in a direction (Z direction) of less than °.

JP 2016-133760 A

In the case of the configuration described in Patent Document 1, when the developing device is moved from the separated position to the contact position, the posture of the developing device is not stabilized, and two points in the X direction or three points in the Z direction are normal. It is possible that they do not abut in position. In this case, there is a possibility that the SD gap cannot be guaranteed, or that twisting occurs in the developing device. If the developing device is twisted, there is a possibility that the gap (SB gap) between the developing sleeve and the regulating blade (regulating means) that regulates the layer thickness of the developer carried on the developing sleeve will shift from the normal position. be.

In addition, in the case of the configuration described in Patent Document 1, depending on the magnitude of the pressure applied to the developing device and the rigidity of the developing device, the developing device may be twisted and a fourth indicated point may occur in the Z direction. Sometimes. Also in this case, the SB gap may deviate from the normal state.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a structure capable of stabilizing the posture of a developing device during movement and suppressing the gap between a developer carrier and a regulating means from being displaced.

The present invention provides an apparatus main body, an image carrier provided in the apparatus main body, and a developer carrier capable of developing an electrostatic latent image on the image carrier by moving while carrying a developer. and a regulating means disposed with a gap between the developer carrier and the developer carrier for regulating the layer thickness of the developer carried on the developer carrier, wherein the developer carrier and the image Provided movably within the apparatus main body at a first position where the gap between the developer carrier and the carrier is a predetermined gap, and a second position where the developer carrier is spaced further from the image carrier than the first position. a pressing means for pressing the developing device toward the image bearing member in a first direction; and a first thrust of the developing device pressed in the first direction at the first position. a first positioning portion that abuts against the contact portion to perform positioning in a second direction, which is a direction in which the gap between the developer carrier and the image carrier is regulated; a second positioning portion that abuts against the pressurized second abutting portion of the developing device to position the developing device in a third direction intersecting the second direction; a first posture regulating portion that regulates the posture of the developing device moving from the second position to the first position at one end in the longitudinal direction intersecting the direction; a second posture regulating portion for regulating the posture of the developing device moving from the second position to the first position; and the first abutting portion when the developing device moves from the second position to the first position. a releasing means for releasing the restriction of the second attitude restricting portion in a state in which the second abutting portion abuts on the first positioning portion and the second abutment portion abuts on the second positioning portion; and a moving member that moves in a predetermined direction. and wherein the second posture regulating portion is formed in the first region of the moving member in the predetermined direction so as to be able to engage with an engaging portion provided on the other end side in the longitudinal direction of the developing device. The releasing means is formed in a second area that is deviated from the first area with respect to the predetermined direction of the moving member, and the first area faces the engaging portion while the moving member moves toward the predetermined direction. While moving in the direction, the posture of the developing device is regulated by the engagement of the second posture regulating portion with the engaging portion, and the moving member moves further in the predetermined direction, thereby engaging the engaging portion. The image forming apparatus , wherein the mating portion faces the second region, thereby releasing the engagement between the second posture regulating portion and the engaging portion, thereby releasing the posture regulation of the developing device. It is in.

Further, the present invention provides an apparatus main body, an image carrier provided in the apparatus main body, and a developer carrier capable of developing an electrostatic latent image on the image carrier by carrying and moving the developer. and a regulating means disposed with a gap between the developer carrier and the developer carrier for regulating the layer thickness of the developer carried on the developer carrier, wherein the developer carrier and the developer carrier Rotation within the apparatus main body between a first position where a gap between the developer carrier and the image carrier is a predetermined gap, and a second position where the developer carrier is separated from the image carrier more than the first position. a developing device that can be provided; a pressing means that presses the developing device toward the image carrier in the first direction; and the developing device that is pressed in the first direction at the first position. a positioning portion for positioning in a second direction, which is a direction in which a gap between the developer bearing member and the image bearing member is regulated by contacting the abutting portion; At one end in the longitudinal direction that intersects the two directions, the developing device is rotatably supported from the second position to the first position, and the movement of the developing device in the direction perpendicular to the rotation axis is regulated. 1 regulating portion and the other end side in the longitudinal direction rotatably support the developing device from the second position to the first position, and restrict movement of the developing device in a direction perpendicular to the rotation axis. and a second restricting portion that moves the developing device from the second position to the first position, and in a state in which the abutting portion is in contact with the positioning portion, the second restricting portion moves the developing device in the second direction. and a releasing means for releasing the restriction in the direction along the direction of the image forming apparatus.

According to the present invention, it is possible to prevent the gap between the developer carrier and the regulating means from shifting while stabilizing the posture of the developing device during movement.

1 is a perspective view showing the image forming apparatus according to the first embodiment with a front cover opened; FIG. 1 is a perspective view showing an image forming apparatus according to a first embodiment with a front cover opened and an inner cover and a small cover omitted; FIG. 1 is a cross-sectional view of a schematic configuration of an image forming apparatus according to a first embodiment; FIG. 1 is a cross-sectional view of a schematic configuration of a process unit according to a first embodiment; FIG. 1 is a perspective view of a developing device according to a first embodiment; FIG. FIG. 6 is a perspective view of the developing device viewed from the opposite direction to FIG. 5; 4 is a perspective view of a small cover, a developing tray, and an interlocking mechanism according to the first embodiment; FIG. 4A and 4B are schematic configuration cross-sectional views showing the contact and separation configuration of the developing device according to the first embodiment, with (a) the small cover closed and (b) the small cover open. 8A and 8B are side views of the separated position of the developing device according to the first embodiment as seen from the front side of the developing device, and FIG. FIG. 4 is a cross-sectional view of a screwed portion of the developing device according to the first embodiment; 2A and 2B are side views of the contact position of the developing device according to the first embodiment as seen from the front side of the developing device, and FIG. 4A and 4B are cross-sectional views of the developing device at the contact position of the developing device according to the first embodiment, and FIG. (a) the relationship between the engaging portion of the developer container and the guide surface at the separated position, and (b) the relationship between the engaging portion and the guide surface in the state of being moved from the separated position to the contact position, according to the first embodiment. Schematic diagrams showing the relationship, (c) respectively showing a state in which the engagement between the engaging portion and the guide surface is disengaged. 8A and 8B are cross-sectional views of the developing device at the contact position of the developing device according to the second embodiment, and FIG.

<First embodiment>
A first embodiment will be described with reference to FIGS. 1 to 13. FIG. First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIGS. 1 to 4. FIG.

[Image forming apparatus]
FIG. 1 shows an overall image of the image forming apparatus 100 with the front cover 101 opened. FIG. 2 is an overall image of the image forming apparatus 100 omitting the inner cover 102 and a part of the frame, and a plurality of horizontally arranged small covers 103 to clarify the arrangement of units inside the apparatus. The image forming apparatus 100 of the present embodiment includes a process unit (image forming section) including a drum unit 210 including a photosensitive drum 211 and a developing unit 220 as a developing device having a developing sleeve 221 arranged opposite to the photosensitive drum 211 . 200.

Four process units 200 for each color of Y (yellow), M (magenta), C (cyan), and K (black) are arranged substantially horizontally at a substantially central position of the apparatus main body 100A of the image forming apparatus 100. are placed. Each process unit 200 forms a toner image of each color. Each process unit 200 is arranged in the apparatus main body 100A while being covered with a small cover 103, as shown in FIG.

As shown in FIG. 3, an intermediate transfer unit 13 is arranged above each process unit 200 . The intermediate transfer unit 13 has an intermediate transfer belt 260 as an intermediate transfer member. The intermediate transfer belt 260 is an endless belt, and is stretched by various rollers such as a secondary transfer roller 13b, an idler roller 13e, and a tension roller 13c. The secondary transfer roller 13b is arranged along the conveying path of the recording material S, and forms a nip (secondary transfer portion) with the opposing roller 21 . Note that the recording material is, for example, a sheet material such as paper or an OHP sheet.

Furthermore, above the intermediate transfer belt 260, four toner cartridges 250 are arranged side by side to supply toner of each color to the developing units 220 of each color. A toner replenishing unit 400 (see FIG. 5), which will be described later and which receives toner from the toner cartridge 250 and transfers the toner to the developing unit 220, is arranged on the back side of the apparatus. Note that the back side of the image forming apparatus 100 is the back side of the apparatus opposite to the front side operated by the user.

The image forming apparatus 100 also has a laser unit (exposure device) 12 and a cassette 8 below the process unit 200 . A transport path 20 for transporting the recording material from the cassette 8 is arranged on the side of the process unit 200 and the laser unit 12 , and the fixing device 3 is arranged along the transport path 20 . Furthermore, a discharge tray 104 or the like for discharging the recording material on which an image is formed is provided above the apparatus.

A document reading device 7 is provided above the discharge tray 104 . A host device such as a personal computer (PC) 60 is communicably connected to the control unit 6 of the image forming apparatus 100 . The image forming apparatus 100 forms a toner image on the recording material S according to an image signal from the document reading device 7 or the PC 60 .

The control unit 6 controls the entire image forming apparatus 100 . Such a control section 6 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU controls each part while reading a program corresponding to the control procedure stored in the ROM. The RAM stores work data and input data, and the CPU performs control by referring to the data stored in the RAM based on the above-described programs and the like.

By disposing the laser unit 12 below the process unit 200, the relative positional relationship between the drum unit 210 and the developing unit 220 is limited. Since the laser from the laser unit 12 passes through the exposure window 12a from below and irradiates the lower surface of the photosensitive drum 211 of each drum unit 210, the developing unit 220 is arranged sideways so as not to block the laser.

The developing unit 220 includes the developing sleeve 221 arranged to face the photosensitive drum 211. For the above reason, the arrangement angle of the developing sleeve 221 is generally within a range of about 60° from the horizontal, and is arranged to face the photosensitive drum 211. be.

Further, the drum unit 210, the developing unit 220, and the intermediate transfer unit 13 are each detachable from the apparatus main body 100A. For this purpose, the image forming apparatus 100 has the front cover 101 as an access door to the inside of the apparatus. Further, as shown in FIG. 1, each process unit 200 is covered with a small cover 103, and the other devices are covered with an inner cover 102. As shown in FIG. Therefore, when the developing unit 220 or the drum unit 210 is to be attached/detached or replaced, the front cover 101 is opened from the front of the main body, and then the small cover 103 is opened to expose the target unit and move in the direction of the arrow G shown in FIG. and can be inserted and removed. Further, the intermediate transfer unit 13 is exposed by opening the front cover 101 and then opening the inner cover 102 so that it can be inserted and removed in the direction of arrow G shown in FIG.

[Process unit]
Next, the configuration of each process unit 200 described above will be described with reference to FIGS. 3 and 4. FIG. First, the drum unit 210 (image carrier unit) has a cylindrical photosensitive drum 211 as an image carrier capable of carrying a toner image. A device 213 and the like are provided. On the other hand, a developing unit 220 as a developing device has a developing container 222 containing developer including toner and carrier. A cylindrical developing sleeve 221 as a developer carrying member capable of carrying a developer is rotatably supported in an opening formed in the developing container 222 at a position facing the photosensitive drum 211 .

An image forming operation process for forming, for example, a four-color full-color image by the image forming apparatus 100 having the process unit 200 configured as described above will be described. The image forming operation starts with feeding the recording material S sheet by sheet from the tray 2 of the cassette 8 provided below the apparatus and conveying it along the conveying path 20 to the secondary transfer portion.

On the other hand, when the image forming operation starts, the charging roller 212 uniformly charges the surface of the photosensitive drum 211 rotating in the direction of the arrow in FIG. Next, the photosensitive drum 211 is exposed to laser light L (FIG. 3) corresponding to image signals emitted from the laser unit 12 . As a result, an electrostatic latent image corresponding to the image signal is formed on the photosensitive drum 211 (on the image carrier). The electrostatic latent image on the photosensitive drum 211 is developed into a visible image by toner contained in the developing unit 220 . In the present embodiment, a reversal development method is used in which toner is adhered to the bright area potential exposed by laser light. Each color toner image formed on the photosensitive drum 211 is primarily transferred onto the intermediate transfer belt 260 by primary transfer rollers 13dY, 13dM, 13dC, and 13dK. Toner remaining on the surface of the photosensitive drum 211 after the primary transfer (transfer residual toner) is removed by the cleaning device 213 .

Such operations are sequentially performed in each of the yellow, magenta, cyan, and black process units 200 to superimpose toner images of four colors on the intermediate transfer belt 260 . Thereafter, the four-color toner images on the intermediate transfer belt 260 are collectively secondary-transferred onto the recording material S conveyed from the cassette 8 in synchronization with the formation timing of the toner images.

Next, the recording material is conveyed to the fixing device 3 and is heated and pressurized to melt and mix the toner on the recording material S, thereby fixing the toner on the recording material as a full-color image. After that, the recording material S is discharged to the discharge tray 104 . This completes a series of image forming processes. It should be noted that it is also possible to form a single-color or multi-color image of a desired color using only a desired image forming unit.

[Development unit]
Next, the detailed configuration of the developing unit 220 of this embodiment will be described with reference to FIGS. 4 to 6. FIG. FIG. 4 is a cross-sectional view of the process unit 200. As shown in FIG. FIG. 5 is a perspective view of the developing unit 220 viewed from the back side. FIG. 6 is a perspective view of the developing unit 220 viewed from the front side.

The developing unit 220 includes a developing sleeve 221 and a developing container 222, and the developing container 222 contains a two-component developer containing toner and carrier as a developer. As will be described later, the developing unit 220 of this embodiment employs a so-called trickle system in which new developer is supplied and surplus developer in the developer container is discharged. The developing sleeve 221 is arranged close to the photosensitive drum 211 with a predetermined gap therebetween. A magnet (not shown) is arranged inside the developing sleeve 221 , and the magnetic force of the magnet causes the developing sleeve 221 to carry the developer.

As for the developer, in this embodiment, a two-component development system is used as a development system, and a mixture of negatively charged non-magnetic toner and a magnetic carrier is used as the developer. The non-magnetic toner is obtained by encapsulating a colorant, a wax component, etc. in a resin such as polyester or styrene-acrylic resin, and pulverizing or polymerizing the resin into a powder. The magnetic carrier is obtained by applying a resin coating to the surface layer of a core made of resin particles kneaded with ferrite particles or magnetic powder.

The developing container 222 is partitioned into a developing chamber 224 (first chamber) and a stirring chamber 225 (second chamber) by a partition wall 223, and developer is contained in the developing chamber 224 and the stirring chamber 225, respectively. In other words, the developing chamber 224 and the stirring chamber 225 are partitioned by the partition wall 223 . The developing chamber 224 and the stirring chamber 225 are adjacent to each other in a substantially horizontal direction and are arranged along the rotation axis direction (longitudinal direction) of the developing sleeve 221 . Both ends of the partition wall 223 do not reach the longitudinal end side walls inside the developer container 222 . As a result, communication ports are formed at both ends of the partition wall 223 to allow the passage of the developer between the developing chamber 224 and the stirring chamber 225 . forms a circulation path of

The developing chamber 224 and the stirring chamber 225 have a first screw 226 and a second screw 227 as circulating conveying members for circulating the developer between the developing chamber 224 and the stirring chamber 225 . That is, in the developing chamber 224 , a first screw 226 as a conveying member that conveys the developer while supplying the developer to the developing sleeve 221 in the developing chamber 224 is arranged parallel to the rotation axis direction of the developing sleeve 221 . there is As the first screw 226 rotates, the developer in the developing chamber 224 is transported in the direction of the rotation axis.

Further, in the stirring chamber 225 , a second screw 227 as a conveying member for stirring and conveying the developer supplied by the toner supply unit 400 as will be described later in the stirring chamber 225 is installed along the rotation axis direction of the developing sleeve 221 . arranged in parallel. As the second screw 227 rotates, the developer in the stirring chamber 225 is transported in the direction opposite to the transport direction of the first screw 226 . The first screw 226 and the second screw 227 are each configured by providing spiral blades on the rotating shaft. As the developer is conveyed while being stirred between the developing chamber 224 and the stirring chamber 225, the toner is negatively charged and the carrier is positively charged.

The developing sleeve 221 rotates in the direction of the arrow in FIG. 4, carries the developer contained in the developing chamber 224, and conveys it toward a regulating blade 228 as a regulating means. The developer carried on the developing sleeve 221 is subjected to a shearing force by the regulating blade 228 and its amount (layer thickness) is regulated to form a developer layer having a predetermined layer thickness on the developing sleeve 221 . A gap (SB gap) between the tip of the regulating blade 228 and the developing sleeve 221 is guaranteed by an adjustment set in the manufacturing process. The developer layer is carried and conveyed to a developing area facing the photosensitive drum 211 . Thereby, the developing sleeve 221 can develop the electrostatic latent image formed on the surface of the photosensitive drum 211 . The developer after being used for development is separated from the developing sleeve 221 and collected in the developing chamber 224 .

As shown in FIG. 6, the developing sleeve 221 is rotatably held by bearings 206 serving as first abutting portions at both ends in the direction of the rotation axis. As will be described later in detail, the bearing 206 abuts against a drum-side abutment portion 214 as a first positioning portion provided in the drum unit 210, so that the developing sleeve 221 and the photosensitive drum 211 are separated by a predetermined distance (SD gap). ) are arranged close to each other.

As shown in FIG. 5, a replenishing section 401 for replenishing the developer containing toner and carrier into the developer container is provided upstream of the second screw 227 of the stirring chamber 225 in the developer conveying direction. The replenishment section 401 is located behind the apparatus main body 100A with the developing unit 220 attached to the apparatus main body 100A, and has a replenishment port 402 and a shutter 403 that open above the second screw 227 . The shutter 403 opens the supply port 402 when the developing unit 220 is inserted into the apparatus main body 100A, and closes the supply port 402 when the developing unit 220 is extracted from the apparatus main body 100A.

The replenishing portion 401 is replenished with developer from a toner replenishing unit 400 as replenishing means provided in the apparatus main body 100A. That is, as shown in FIG. 3, a toner cartridge 250 containing developer for replenishment is arranged above the developing unit 220 , and the developer is supplied from the toner cartridge 250 to the toner replenishing unit 400 .

A driving coupling 207 for driving the developing sleeve 221 and the first and second screws 226 and 227 is provided beside the replenishing portion 401 of the developing container 222 . The developing sleeve 221 and the first and second screws 226 and 227 are rotationally driven by inputting drive to the drive coupling 207 from a motor 500 as a drive source inside the apparatus. The developer is agitated by this rotational driving and further circulates in the developer container 222 .

The developer replenished into the stirring chamber 225 through the replenishing portion 401 in this way is conveyed while being stirred by the rotation of the second screw 227, so that the toner and the carrier rub against each other and are triboelectrically charged. Then, it is used for development by being further transported to the development chamber 224 . Furthermore, since the amount of developer in the developer container 222 increases due to the replenishment of the developer in this way, in the present embodiment, a discharge section ( (not shown) are provided. That is, of the developer, toner is used for development, but carrier remains in the developer container 222 without being used for development. Then, the carrier gradually deteriorates, resulting in a decrease in charging performance. For this reason, part of the developer is discharged by the discharge unit to keep the amount of developer in the developer container 222 within a predetermined range, and the deteriorated carrier is discharged.

[Attaching and removing the development unit]
The developing unit 220 is assumed to be detachable/replaceable from the apparatus main assembly 100A. Therefore, the configuration and operation for attaching and detaching the developing unit 220 will be described using FIGS. 7 to 12 while referring to FIG. First, as described above, the developing unit 220 is arranged with the developing sleeve 221 facing the photosensitive drum 211 with a predetermined gap (SD gap). Since the SD gap is very small, if the developing unit 220 or the drum unit 210 is pulled forward from the apparatus main assembly 100A, the photosensitive drum 211 or the developing sleeve 221 may be scratched. Therefore, when the developing unit 220 or the drum unit 210 is attached or detached, they are first separated by a sufficient distance so that they do not rub against each other.

Therefore, in this embodiment, the contact/separation mechanism 240 is provided to move the developing unit 220 away from and close to the drum unit 210 . That is, the developing unit 220 has a contact position (first position) where the gap between the developing sleeve 221 and the photosensitive drum 211 is a predetermined gap, and a separated position where the developing sleeve 221 is separated from the photosensitive drum 211 more than the contact position. (second position) and is movably provided in the apparatus main body. The contact/separation mechanism 240 moves the developing unit 220 between such contact position and separation position.

When removing any unit, the contact/separation mechanism 240 separates the developing unit 220 from the drum unit 210 and moves it to the separated position. Further, insertion of either unit into the apparatus main body 100A is also performed in a state in which the developing unit 220 is separated from the drum unit 210 by the contact/separation mechanism 240 . After the insertion, the developing unit 220 is moved to the abutting position, and the developing unit 220 is brought closer to the drum unit 210 .

As shown in FIG. 7, the contact/separation mechanism 240 has a development pressure stay 241 as a moving member and a link mechanism 244 as an interlocking mechanism. The developing pressurizing stay 241 is arranged inside the developing tray 231 fixed to a front side plate and a rear side plate (not shown) constituting a frame supporting each unit in the apparatus main body 100A in the direction of an arrow G (insertion/extraction of the developing unit 220). direction, longitudinal direction). The developing unit 220 is inserted and removed along the developing tray 231 when it is inserted into and removed from the apparatus main assembly 100A. The longitudinal direction is a direction intersecting first to third directions described later, and in the present embodiment, the longitudinal direction is a direction orthogonal to the first to third directions.

The developing pressurizing stay 241 is provided with pressurizing springs 242 and 243 as pressurizing means for pressurizing the developing unit 220 toward the photosensitive drum 211 . That is, the development pressure stay 241 has a first plate portion 241a and a second plate portion 241b. The first plate portion 241a is substantially orthogonal to the pressing direction (first direction described later) of the pressing springs 242 and 243 and extends in the arrow G direction (longitudinal direction). The second plate portion 241b is bent substantially at a right angle from the end portion in the width direction perpendicular to the longitudinal direction of the first plate portion 241a and extends in the arrow G direction.

Pressure springs 242 and 243 are provided on both longitudinal ends of the first plate portion 241a (the front side and the back side of the image forming apparatus 100), respectively. Pressure springs 242 and 243 arranged at two locations on the front side and the back side of the development pressure stay 241 are configured to be elastically deformable, and are plate springs in this embodiment. However, such pressurizing means may have other configurations such as a coil spring other than the leaf spring. For example, by holding the pressure piece so as to be able to swing and pressing one side of the swing center of the pressure piece with an elastic member such as a spring, the other side of the swing center of the pressure piece presses. Configuration is fine.

The small cover 103 is connected via a link mechanism 244 to the end portion of the development pressure stay 241 on the front side of the image forming apparatus 100 . The link mechanism 244 is composed of a rotary link 245 connected to the small cover 103 by a link shaft 103B, and a development pressure link 246 connected to the rotary link 245 by a link shaft 246A. The development pressure link 246 is fixed to the front end of the development pressure stay 241 . By connecting the small cover 103 and the developing pressurizing stay 241 via the link mechanism 244 in this way, the developing pressurizing stay 241 is moved in the direction of the arrow G in conjunction with the opening/closing operation of the small cover 103. there is

This point will be described with reference to FIGS. 8A shows a state (pressurized state) in which the developing unit 220 is in the contact position, and FIG. 8B shows a state in which the developing unit 220 is in the separated position.

The small cover 103 is provided on the apparatus main body 100A so as to be openable and closable, and is a cover that covers the developing unit 220 mounted on the apparatus main body 100A in a closed state. The link mechanism 244 moves the developing pressure stay 241 in a predetermined direction in conjunction with the operation of closing the small cover 103 from the open state, and the development pressure stay 241 is associated with the operation of opening the small cover 103 from the closed state. The pressure stay 241 is moved in a direction opposite to the predetermined direction. The predetermined direction is the direction of the arrow G from the back side to the front side of the apparatus main body 100A (the direction of the arrow C), and the opposite direction to the predetermined direction is the direction of the arrow G from the front side to the back side of the apparatus main body 100A. direction (direction of arrow F).

First, in the state of the contact position shown in FIG. 8A, the pressure spring 242 provided on the development pressure stay 241 and the development pressure portion 201A provided on the development container 222 of the development unit 220 are brought into contact. touch. The developing pressurizing portion 201A is continuous with an inclined surface 201Aa inclined in a direction approaching the first plate portion 241a of the developing pressurizing stay 241 toward a predetermined direction (direction of arrow C), and a downstream side of the inclined surface 201Aa in the predetermined direction. and a flat surface 201Ab parallel to the predetermined direction.

The pressure spring 242 includes a pressure portion 242a on the distal end side that is a free end, a fixing portion 242b on the base end side that is a fixed end fixed to the first plate portion 241a, the pressure portion 242a and the fixing portion 242b. and a connecting portion 242c that connects the . The connecting portion 242c is inclined substantially parallel to the inclined surface 201Aa. In addition, the direction of the pressing spring 242 from the fixing portion 242b to the pressing portion 242a is opposite to the predetermined direction.

Although FIG. 8A only shows the configuration of the front portion of the developing unit 220, in the state of the abutment position, the pressure spring 243 and the developing container 222 are provided in the rear portion of the developing unit 220 as well. The developing pressurizing portion 201B abuts thereon (see FIG. 11(b)). Similarly to the pressure spring 242, the pressure spring 243 also has a pressure portion 243a, a fixed portion 243b, and a connecting portion 243c that connects the pressure portion 243a and the fixed portion 243b (FIG. 7). . The developing pressurizing portion 201B also has an inclined surface and a flat surface like the developing pressurizing portion 201A.

8A, the pressure portion 242a of the pressure spring 242 contacts the flat surface 201Ab on the front side of the developer container 222, and the pressure portion 243a of the pressure spring 243 contacts the rear side of the developer container 222. are in contact with the flat surfaces on the sides. As a result, the developing unit 220 is pressed against the drum unit 210 by the pressing springs 242 and 243 .

When the developing unit 220 is retracted from the contact position to the separated position, the opening of the small cover 103 serves as a trigger. The small cover 103 is rotatable around a rotation shaft 103A, and is connected to a rotation link 245 of a link mechanism 244 by a link shaft 103B provided at its tip. The rotary link 245 is further connected to the developing pressurizing link 246 via a link shaft 246A.

When the small cover 103 is rotated counterclockwise from the state shown in FIG. 8(a), the link shaft 103B rotates, and the development pressure stay 241 moves through the rotation link 245 to the state shown in FIG. 8(b). , is pushed in the direction of arrow F (moves in the direction opposite to the predetermined direction). When the developing pressurizing stay 241 is pushed in direction F in FIG. 243a and slides down along the slopes of the connecting portions 242c, 243c. At this time, an inclined surface 201Aa is formed on the downstream side in the F direction of the developing pressurizing portion 201A, and an inclined surface is similarly formed on the downstream side in the F direction of the developing pressurizing portion 201B. Therefore, the developing unit 220 moves in the direction of arrow E along guide grooves 222B and 231A (see, for example, FIGS. 9A and 9B), which will be described later. As the developing unit 220 moves in the E direction, the developing sleeve 221 retreats and separates from the photosensitive drum 211 .

On the other hand, when the small cover 103 is rotated clockwise from the state shown in FIG. As shown, it is pulled in the direction of arrow C (moves in a predetermined direction). When the developing pressurizing stay 241 is pulled in the direction C in FIG. 243c and rides on the pressurizing portions 242a and 243a. At this time, the developing unit 220 moves in the arrow D direction along the guiding grooves 222B and 231A. As the developing unit 220 moves in the D direction, the developing sleeve 221 approaches the photosensitive drum 211 .

As shown in FIG. 8A, when the small cover 103 is closed, both the developing unit 220 and the drum unit 210 cannot be accessed, as shown in FIG. . Therefore, it is possible to prevent an erroneous operation such as inserting/removing these units in the state of FIG. 8(a).

[Positioning Configuration of Developing Unit]
Next, the positioning structure of the developing unit 220 will be described with reference to FIGS. 9(a) to 13(c). 9A and 9B show the state where the developing unit 220 is at the separated position. The developing unit 220 is inserted along the developing tray 231 into the apparatus main body 100A. Then, as shown in FIG. 9B, first, the projection 201C provided at one end in the longitudinal direction (rear side in the insertion direction) of the developing unit 220 is moved to the far end of the developing tray 231. As shown in FIG. It penetrates into the formed guide groove 231A as the first posture regulating portion. By fitting the protrusion 201C into the guide groove 231A, the rear side position of the developing unit 220 is restricted.

The protrusion 201C protrudes further to the other side from the other longitudinal end of the developing unit 220 and has a substantially cylindrical shape. The guide groove 231A is a through hole formed in the wall portion 231B of the development tray 231 on the back side, and is an elongated hole portion formed along the movement direction of the development unit 220. As shown in FIG. Since the outer diameter of the protrusion 201C is slightly smaller than the width of the guide groove 231A (the width in the direction perpendicular to the direction in which the protrusion 201C is guided), the protrusion 201C fits into the guide groove 231A and is 231A, that is, inside the guide groove 231A (inside the elongated hole).

On the other hand, as shown in FIG. 9A, a projecting plate portion 222A is provided at the other end in the longitudinal direction of the developing unit 220 (the front side in the insertion direction) so as to project upward from the developing container 222. As shown in FIG. ing. A guide groove 222B formed substantially parallel to the guide groove 231A is provided in the protruding plate portion 222A so as to penetrate the protruding plate portion 222A. The guide groove 222B is also an elongated hole formed along the movement direction of the developing unit 220. As shown in FIG.

As described above, when the developing unit 220 is inserted along the developing tray 231 and the projecting portion 201C is fitted into the guiding groove 231A, the projecting plate portion 222A contacts the frame 110 of the apparatus main body 100A as shown in FIG. come in contact with or come close to A screw hole 110A is formed in the frame 110 at a position aligned with the guide groove 222B. By screwing the stepped screw 229 into the screw hole 110A through the guide groove 222B while the projecting plate portion 222A is in contact with or close to the frame 110, the longitudinal position of the developing unit 220 is regulated. As will be described later, the positioning of the developing unit 220 in the front direction is performed by engaging the flat surface portion 300 as the second posture regulating portion with the engaging portion 301 of the developing unit 220 (see FIG. 12A). ).

The stepped screw 229 has a threaded portion 229A, a loose fitting portion 229B, and a flange portion 229C in this order from the tip. The threaded portion 229A is screwed into the threaded hole 110A. The loose fitting portion 229B has a larger diameter than the threaded portion 229A and is loosely fitted into the guide groove 222B. The flange portion 229C faces a portion of the projecting plate portion 222A around the guide groove 222B.

Here, since the length of the loose fitting portion 229B is larger than the thickness of the protruding plate portion 222A in which the guide groove 222B is formed, the flange portion 229C and the frame are separated from each other while the stepped screw 229 is screwed into the screw hole 110A. 110 becomes larger than the thickness of the projecting plate portion 222A. Further, the loose fitting portion 229B has an outer diameter smaller than the width of the guide groove 222B and is loosely fitted so as to be movable in the guide groove 222B. Therefore, even if the protruding plate portion 222A is screwed to the frame 110 by the stepped screw 229, it is guided by the engagement between the stepped screw 229 and the guide groove 222B, and is attached to the frame 110 and the stepped screw 229. can move relative to each other. The stepped screw 229 corresponding to the guide groove 222B on the near side and the projection 201C corresponding to the guide groove 231A on the far side are not on the same line, but are shifted so as to sandwich the center of gravity of the developing unit 220. are placed.

9A and 9B described above show the state in which the developing unit 220 shown in FIG. 8B is at the separated position. By closing the small cover 103 from this state, the developing unit 220 is moved to the contact position shown in FIGS.

That is, as described above, when the small cover 103 is closed, the development pressure stay 241 is pulled in, and the pressure springs 242 and 243 move the development unit 220 in the first direction (see FIGS. 12A and 12B to be described later). arrow P direction). At this time, the developing unit 220 moves to the positions shown in FIGS. 11A and 11B along the guide grooves 222B and 231A.

Here, as shown in FIGS. 12A and 12B, the drum unit 210 is provided with a drum side contact portion 214 as a first positioning portion which is formed so as to protrude toward the developing unit 220 side. ing. A frame 111 of the apparatus main body 100A (see FIG. 1, etc.) positioned above the developing unit 220 is provided with a main body side contact portion 112 as a second positioning portion.

On the other hand, the developing unit 220 has a bearing 206 as a first abutting portion that supports both ends of the developing sleeve 221 (see FIG. 6, etc.) in the rotation axis direction. In addition, a development-side abutting portion 222C as a second abutting portion is provided on the upper surface of the developer container 222 of the developing unit 220 so as to protrude upward.

When the developing unit 220 moves toward the contact position (first position), first, the bearing 206 of the developing unit 220 pressurized in the first direction (arrow P direction) contacts the drum side contact portion 214 of the drum unit 210 . abut. As a result, the developing unit 220 is positioned with respect to the drum unit 210 in the second direction (arrow Q direction), which is the direction in which the gap between the developing sleeve 221 and the photosensitive drum 211 is restricted. And the SD gap is guaranteed.

Thereafter, the developing unit 220 moves upward while being in contact with the drum side contact portion 214, and the developing contact portion 222C of the developing unit 220 pressed in the first direction contacts the main body side contact portion 112 of the apparatus main body 100A. abut. As a result, the development unit 220 is positioned with respect to the drum unit 210 in the third direction (arrow R direction) that intersects with the second direction. Then, the position of the developing unit 220 in the height direction is determined.

When the developing unit 220 moves to the contact position in this manner, the bearing 206 contacts the drum-side contact portion 214 and the developing contact portion 222C contacts the main body-side contact portion 112, respectively, and the position of the developing unit 220 is determined. Note that the bearing 206 and the drum-side contact portion 214 are provided at two locations separated in the longitudinal direction, and perform positioning in the second direction at two points. The development-side abutting portion 222C and the main-body-side abutting portion 112 are also provided at two locations separated in the longitudinal direction, and positioning in the third direction is performed at two points.

Note that the above-described second direction (arrow Q direction) is a direction connecting the center O1 of the photosensitive drum 211 and the center O2 of the developing sleeve 221 . Further, the third direction (arrow R direction) is a direction forming an angle of 90° or more and less than 180° with the second direction. In this embodiment, the angle between the second direction and the third direction is 90°.

The first direction (arrow P direction) is a direction passing between the drum-side contact portion 214 and the body-side contact portion 112 . Here, a direction orthogonal to the direction of arrow Q and passing through the contact position between the bearing 206 and the drum side contact portion 214 and a direction orthogonal to the direction of arrow R and extending between the developing contact portion 222C and the main body side contact portion 112 Let θ be the wedge angle formed by the direction passing through the abutment position. In this case, the first direction in the present embodiment is substantially parallel to the bisector of the wedge-shaped angle θ and directed toward the vicinity of the center of the wedge. This is to prevent the components of the pressing force of the pressing springs 242 and 243 from acting in the direction of twisting the developing unit 220 .

As described above, the guide groove 222B on the front side of the developing unit 220 is loosely fitted with the loose fitting portion 229B of the stepped screw 229. When the developing unit 220 is moved, the loose fitting portion 229B is displaced from the guide groove 222B. Relative movement along one side. On the other hand, when the developing unit 220 moves to the abutment position, the loose fitting portion 229B is out of contact with the guide groove 222B.

On the other hand, the protrusion 201C on the far side of the developing unit 220 is fitted in the guide groove 231A (first posture regulating portion) on the far side of the developing tray 231, and when the developing unit 220 moves, the protrusion 201C 201C moves along the guiding groove 231A. Also when the developing unit 220 moves to the contact position, the projection 201C and the guide groove 231A are in a fitting relationship. Therefore, the guiding groove 231A regulates the attitude of the developing unit 220 moving from the separated position to the contact position at one longitudinal end (rear side) of the developing unit 220 .

As shown in FIG. 12(b), a drive coupling 207 is provided on the far side of the developing unit 220 to which the drive from the motor 500 (see FIG. 5) of the apparatus main assembly 100A is input. Then, when the drive from the motor 500 is input, a clockwise rotational force in FIG. Therefore, in the present embodiment, the protrusion 201C is fitted into the guide groove 231A on the back side of the developing unit 220, which is the drive input side, so as to restrict the rotation of the developing unit 220 due to such drive input. ing. That is, in order to regulate the rotation of the developing unit 220, one constraint point of the developing unit 220 is provided on the driving side.

On the other hand, as shown in FIG. 12A, the front side of the developing unit 220 is engaged with the engaging portion 301 of the developing unit 220 with the flat portion 300 (broken line) as the second posture regulating portion. This point will be described with reference to FIGS. 13(a) to 13(c) while referring to FIGS. 7, 12(a) and 12(b).

13(a) to 13(c) are cross-sectional views taken along the line AA in FIG. 12(a). FIG. 13(a) shows a state in which the developing unit 220 is at the separated position. FIG. 13B shows a state in which the flat portion 300 and the engaging portion 301 are not released from the engagement with the developing unit 220 moved to the contact position. FIG. 13C shows a state in which the flat portion 300 and the engaging portion 301 are disengaged with the developing unit 220 at the contact position.

As described above, the development pressure stay 241 as a moving member that moves in a predetermined direction has the first plate portion 241a and the second plate portion 241b. Pressure springs 242 and 243 are provided on both longitudinal ends of the first plate portion 241a.

On the other hand, the second plate portion 241 b is formed in a direction along the pressing direction of the pressure springs 242 and 243 and faces a portion of the developing container 222 of the developing unit 220 . The second plate portion 241b is formed with a flat portion 300 as a second posture regulating portion and a concave portion 302 as a releasing means. The flat portion 300 is formed along the moving direction and the longitudinal direction of the developing unit 220 , and the recessed portion 302 is formed to be recessed from the flat portion 300 in the direction away from the developing unit 220 . In this embodiment, the portion of the second plate portion 241b excluding the recessed portion 302 is a flat surface formed in the longitudinal direction so as to face a portion of the developer container 222, and a portion of this flat surface is recessed. A concave portion 302 is formed by aligning them.

An engaging portion 301 is formed at a position facing the second plate portion 241b on the front side of the developing container 222. As shown in FIG. Of the portion facing the second plate portion 241b of the developer container 222, the portion where the engaging portion 301 is not formed is formed so as to retreat in the direction away from the second plate portion 241b rather than the engaging portion 301. ing. Therefore, this portion does not contact the second plate portion 241b while the developing unit 220 is moving between the contact position and the separation position.

The flat portion 300 regulates the posture of the developing unit 220 moving from the separated position (second position) to the contact position (first position) on the other longitudinal end side (front side) of the developing unit 220 . The concave portion 302 is formed when the developing unit 220 moves from the separated position to the contact position, the bearing 206 contacts the drum side contact portion 214, and the developing side contact portion 222C contacts the main body side contact portion 112. , release the regulation of the flat portion 300 .

For this reason, the planar portion 300 is formed in the first region α of the second plate portion 241b in a predetermined direction (direction of arrow G) so as to be able to engage with the engaging portion 301 provided on the other longitudinal end side of the developing unit 220. It is Further, the concave portion 302 is formed in a second region β that is deviated from the first region α with respect to the predetermined direction of the second plate portion 241b. The second region β exists upstream of the first region α in a predetermined direction.

Then, as shown in FIGS. 13A and 13B, while the developing pressure stay 241 is moving in a predetermined direction while the first region α faces the engaging portion 301, the flat portion 300 is The posture of the developing unit 220 is regulated by engaging with the engaging portion 301 . That is, when the small cover is closed, the developing pressure stay 241 moves in a predetermined direction, and the developing unit 220 moves from the separated position to the contact position as described above. At this time, the developing unit 220 moves along the guide grooves 231A and 222B as described above. Since the projection 201C and the guide groove 231A are fitted on the inner side of the developing unit 220, the posture of the developing unit 220 is restricted.

On the other hand, on the front side of the developing unit 220, the stepped screw 229 is loosely fitted in the guide groove 222B, and the posture of the front side of the developing unit 220 is not regulated in this state. For example, it tends to rotate toward the center of gravity of the developing unit 220 (counterclockwise in FIG. 12A) about the contact position between the stepped screw 229 and a portion of the guide groove 222B. Therefore, in the present embodiment, while the developing unit 220 is moving from the separated position to the contact position, the engaging portion 301 faces the first area α as shown in FIGS. I am trying to As a result, the engaging portion 301 of the developing unit 220 is engaged with the flat portion 300 to restrict the rotation of the developing unit 220 as described above.

It should be noted that the pressure springs 242 and 243 keep the developing pressure stay 241 moving in the predetermined direction while the developing pressure stay 241 moves in the predetermined direction while the first region α faces the engaging portion 301 . Along with this, the developing unit 220 is moved from the separated position to the contact position while being pressurized. That is, as the developing pressure stay 241 moves in a predetermined direction, the developing unit 220 moves until the bearing 206 contacts the drum side contact portion 214 and the developing contact portion 222C contacts the main body side contact portion 112, respectively. . In this state, there are two points: the bearing 206 and the drum-side contact portion 214; The developing unit 220 is restrained at one point of the engaging portion 301 and the plane portion 300 .

Here, for example, there is a case where the accuracy of the single constraint point between the engaging portion 301 on the front side and the flat portion 300 is not good, and the developing unit 220 is not positioned at the proper position in such a constrained state. For example, if the rigidity of the developing unit 220 is low, or the pressing force of the pressure springs 242 and 243 is too large, and the developing unit 220 is twisted, the developing unit 220 is at the contact position as described above. You may become constrained. In this case, the gap (SB gap) between the tip of the regulating blade 228 and the developing sleeve 221 may deviate from the normal state. If the SB gap is misaligned, the developing sleeve 221 may be poorly coated with the developer, resulting in an image defect.

Therefore, in the present embodiment, after restraining the developing unit 220 at the contact position as described above, the restraint at one point is released. Specifically, as shown in FIG. 13(c) from the state of FIG. 13(b), the developing pressure stay 241 is further moved in a predetermined direction. Then, the engaging portion 301 is made to face the concave portion 302 by making the engaging portion 301 face the second region β. As a result, the planar portion 300 and the engaging portion 301 are disengaged, and the regulation of the posture of the developing unit 220 is released. That is, when the engaging portion 301 faces the concave portion 302, the engaging portion 301 does not come into contact with the second plate portion 241b, so the posture of the developing unit 220 is not restricted.

It should be noted that the pressure springs 242 and 243 are kept at the contact positions even when the development pressure stay 241 moves further in the predetermined direction and the engaging portion 301 faces the second region β that is out of the first region α. to pressurize the developing unit 220 . That is, in the state of FIG. 13C, the developing unit 220 includes the bearing 206 and the drum-side contact portion 214, the developing contact portion 222C and the body-side contact portion 112, and the back projection 201C and the guide groove 231A. It is pressurized by pressurizing springs 242 and 243 while being constrained at each point.

In summary, the second plate portion 241b of the developing pressure stay 241 has a first region α that contacts the engaging portion 301 and a second region that does not contact the engaging portion 301 in the moving region of the developing pressure stay 241 in a predetermined direction. has β. The planar portion 300 is provided in the first region α, and contacts the engaging portion 301 of the developing unit 220 when the developing unit 220 moves from the separated position to the contact position. The region from the separation position of the developing unit 220 until the bearing 206 and the drum-side contact portion 214 abut against the developing abutment portion 222C and the main body-side abutment portion 112 (FIGS. 13A and 13B). )), the engaging portion 301 moves along the plane portion 300 . After that, when the development pressure stay 241 moves further in a predetermined direction, the engaging portion 301 faces the concave portion 302 and the regulation of the engaging portion 301 is released. As described above, such movement of the developing pressure stay 241 is performed in conjunction with the closing operation of the small cover 103 . The position of the concave portion 302 formed in the developing pressure stay 241 is such that the regulation of the engaging portion 301 is released when the small cover 103 is closed.

As described above, in the present embodiment, when the developing unit 220 is moved, the projection 201C and the guide groove 231A are fitted on the back side, and the engagement portion 301 and the flat portion 300 are engaged on the front side. You can stabilize your posture. Therefore, it is possible to prevent the development unit 220 from being positioned at a position that deviates from the normal position due to the development unit 220 moving out of position.

For example, if the developing unit 220 is moved without regulating the posture of the front side, only the front side will rotate in the direction of the center of gravity, and there is a possibility that the front side of the developing unit 220 will deviate from its normal position. In this case, the SD gap may change in the longitudinal direction, causing an image defect. On the other hand, in the present embodiment, since the posture of the developing unit 220 is regulated even on the front side during movement, the developing unit 220 can be moved while stabilizing the posture. As a result, at the contact position, the bearing 206 and the drum-side contact portion 214, and the developing contact portion 222C and the main body-side contact portion 112 can be brought into contact at regular positions, and the SD gap can be stabilized. can be guaranteed.

Further, after the bearing 206 and the drum-side contact portion 214 and the developer contact portion 222C and the main-body-side contact portion 112 are brought into contact with each other, the engagement portion 301 on the front side and the plane portion 300 are engaged. is released, it is possible to suppress the deviation of the SB gap.

Since the engaging portion 301 and the flat portion 300 where the restraint is finally released in this way are on the side where the drive is not input to the developing unit 220, the influence of the drive input to the developing unit 220 is not affected even if the restraint is released. Few. On the other hand, the protrusion 201C on the drive input side and the guide groove 231A are fitted even after the bearing 206 and the drum-side contact portion 214 and the developing contact portion 222C and the main body-side contact portion 112 are brought into contact with each other. remains joined. Therefore, the rotation of the developing unit 220 due to the drive input can be restricted.

As described above, in the case of the present embodiment, after the posture of the developing unit 220 in the front and back is guided to an appropriate position, the restraint on one side is released. For this reason, when there is a difference in degree of warp or distortion between the front side and the back side of the developing unit 220, generation of a force component in the direction of twisting the developing unit 220 can be suppressed. Therefore, the SB gap that has been adjusted once by the developing unit 220 is not disturbed, and the occurrence of image defects such as image density unevenness due to variations in the SB gap can be suppressed.

Further, in the case of the present embodiment, when the rigid developing unit 220 is warped or distorted, the developing sleeve 220 does not need to correct the warp or distortion of the developing unit 220 by increasing the pressing force of the pressure spring. 221 and the photosensitive drum 211 can be guaranteed. For example, when positioning the developing unit 220 without releasing the restraint on the front side, the pressure force of the pressure spring can be increased to correct the warpage and distortion of the developing unit 220 to ensure the SD gap. Conceivable. On the other hand, in the present embodiment, the development unit 220 is positioned by moving the development unit 220 while its posture is restricted on the front side and the back side, and the restraint on the front side is finally released. At this time, even if the restraint on the front side is released and the warp and distortion of the developing unit 220 are restored, the contact state between the bearing 206 and the drum side contact portion 214, and between the developing contact portion 222C and the main body side contact portion 112 is is maintained, so the SD gap is guaranteed.

Further, when increasing the pressing force of the pressing spring, it is required to increase the rigidity of the parts of the apparatus main body 100A of the image forming apparatus 100 in order to receive this pressing force. If the rigidity of the parts of the apparatus main body 100A is increased, a large amount of material is used, resulting in an increase in the size of the apparatus, and the use of high-strength materials results in an increase in cost. On the other hand, in the case of the present embodiment, the SD gap can be guaranteed without increasing the pressing force of the pressing spring, so that the size and cost of the device are not increased.

<Second embodiment>
A second embodiment will be described using FIGS. 14A and 14B while referring to FIGS. 1 to 7. FIG. In the first embodiment, the configuration in which the developing unit 220 is substantially slid along the guide grooves 222B and 231A has been described. On the other hand, in this embodiment, the development unit 220A is moved from the separated position to the contact position by rotating the developing unit 220A. Since other configurations and actions are the same as those of the first embodiment described above, the same configurations are denoted by the same reference numerals, and explanations and illustrations are omitted or simplified, and hereinafter, the first embodiment. The description will focus on the different parts.

The developing unit 220A as the developing device of the present embodiment is rotatably provided within the apparatus main body 100A (see FIG. 1, etc.) between a contact position as a first position and a separated position as a second position. It is The relationship between the contact position and the separation position is the same as in the first embodiment.

In such a developing unit 220A, as shown in FIG. 14(b), a rotating shaft 602 rotates to a fitting portion 603 as a first restricting portion at one longitudinal end side (rear side) of the developing unit 220A. movably supported. On the other hand, as shown in FIG. 14(a), the rotation shaft 601 is rotatably supported by a regulation mechanism 703 as a second regulation portion on the other longitudinal end side (front side). The rotary shafts 601 and 602 are provided coaxially in parallel with the longitudinal direction of the developing unit 220A.

The regulating mechanism 703 is composed of an elongated hole portion 701 and a regulating member 702, and the regulating member 702 can enter and retreat from the elongated hole portion 701 formed in the frame of the apparatus main body. is provided in A fitting portion 603 is also formed on the frame of the apparatus main body.

In this embodiment, the developing unit 220A is pressed in the first direction (arrow U direction) toward the photosensitive drum 211 by a pressure spring 600 as pressure means. As a result, the developing unit 220 rotates about the rotation shafts 601 and 602 in the arrow W direction.

Also in this embodiment, the developing unit 220A has bearings 206 as abutting portions that support both ends of the developing sleeve 221 (see FIG. 6, etc.) in the rotation axis direction. On the other hand, the drum unit having the photosensitive drum 211 is provided with a drum-side contact portion 214A as a positioning portion that protrudes toward the developing unit 220A.

At the contact position, the bearing 206 of the developing unit 220A pressurized in the first direction contacts the drum-side contact portion 214A. As a result, positioning is performed in the second direction (the direction of arrow V), which is the direction for regulating the gap between the developing sleeve 221 and the photosensitive drum 211 . In the case of this embodiment as well, the bearing 206 and the drum-side contact portion 214A are provided at two locations apart from each other in the longitudinal direction, and positioning in the second direction is performed at two points. The second direction is the direction connecting the center of the photosensitive drum 211 and the center of the developing sleeve 221 . The longitudinal direction is a direction intersecting the first direction and the second direction, and in the present embodiment, the longitudinal direction is a direction perpendicular to the first direction and the second direction.

As described above, the fitting portion 603 rotatably supports the developing unit 220A from the separated position to the contact position at one longitudinal end of the developing unit 220A. Along with this, the fitting portion 603 restricts the movement of the developing unit 220A in the direction orthogonal to the rotation shaft 602. As shown in FIG. That is, the fitting portion 603 has a through hole having an inner diameter slightly larger than the outer diameter of the cylindrical rotating shaft 602, and the rotating shaft 602 is fitted into the through hole. is rotatable, and the movement in the direction perpendicular to the rotation shaft 602 is restricted. In the case of the present embodiment as well, the drive for driving the developing sleeve 221 is input from one longitudinal end of the developing unit 220A.

The regulation mechanism 703 rotatably supports the developing unit 220A from the separated position to the contact position at the other end in the longitudinal direction, and regulates the movement of the developing unit 220A in the direction orthogonal to the rotation shaft 601. . As a result, the developing unit 220A moves from the separated position to the contact position (corresponding to the state shown in FIGS. 13A and 13B of the first embodiment), so that the rotating shafts 601 and 601 Movement in a direction orthogonal to 602 is restricted.

Here, also in the case of this embodiment, similarly to the configuration shown in FIG. 7 of the first embodiment, there is provided a link mechanism 244A that moves the restricting member 702 in conjunction with the opening and closing of the small cover 103 . The link mechanism 244A as a release means is configured to move the developing unit 220A from the separated position to the contact position, and the bearing 206 is in contact with the drum-side contact portion 214A. Release the restrictions on the direction.

That is, the long hole portion 701 into which the restricting member 702 can enter and retreat is formed along the second direction. Therefore, the rotating shaft 601 fitted in the elongated hole portion 701 is allowed to move in the second direction along the elongated hole portion 701 when the restricting member 702 is retracted. The width of the elongated hole portion 701 is slightly larger than the outer diameter of the cylindrical rotating shaft 601 so that the rotating shaft 601 can move in the elongated hole portion 701 in the second direction. Movement in a direction orthogonal to the second direction is restricted.

On the other hand, the regulating member 702 is arranged to sandwich the rotating shaft 601 fitted in the elongated hole portion 701 from both sides in the second direction, and restricts the rotating shaft 601 from moving along the second direction. is doing. In a state corresponding to FIGS. 13A and 13B of the first embodiment, the regulating member 702 enters into the elongated hole 701 and regulates the movement of the rotating shaft 601 in the second direction. do. Next, when the state corresponding to FIG. 13C of the first embodiment is reached, the link mechanism 244A moves so as to retreat from the elongated hole portion 701, and the rotation shaft 601 moves in the second direction. allow.

In the case of this embodiment, when the developing unit 220A rotates (moves), the rotation shaft 602 and the fitting portion 603 are fitted on the back side, and the rotation shaft 601 on the front side is moved. and the regulation mechanism 703, the posture can be stabilized. Therefore, it is possible to prevent the development unit 220A from being positioned at a position deviated from the normal position due to the posture being lost when the development unit 220A is rotated.

Further, after moving to the contact position and bringing the bearing 206 into contact with the drum side contact portion 214A, the engagement between the rotation shaft 601 on the near side and the regulation mechanism 703 is released. That is, by withdrawing the restricting member 702 from the elongated hole portion 701, the rotation shaft 601 is allowed to move in the second direction. Therefore, even if the developing unit 220A is twisted and the bearing 206 and the drum-side contact portion 214A come into contact with each other, the twisting is canceled by releasing the engagement on the front side. It is possible to suppress the deviation of the SB gap.

<Other embodiments>
In each of the above-described embodiments, after the developing unit moves to the contact position, the restraint on the front side is released, but the restraint on the back side may be released.

The present invention can be applied to image forming apparatuses such as copiers, printers, facsimiles, and multifunction machines having a plurality of these functions. Further, the present invention can be applied to a monochrome image forming apparatus that forms a monochromatic image in addition to a full-color image forming apparatus.

100 Image forming apparatus/100A Apparatus main body/103 Small cover (cover)/112 Main body side contact portion (second positioning portion)/201C Protrusion/206. Bearing (first abutment portion, abutment portion)/211 Photosensitive drum (image carrier)/214, 214A Drum side abutment portion (first positioning portion, positioning portion)/220, 220A Developing unit (developing device)/221 Developing sleeve (developer carrying member)/222C Developing side abutment portion (second abutment portion)/228 Regulating blade (regulating means) )/231A Guide groove (first posture regulating portion)/241 Developing pressure stay (moving member)/242, 243, 600 Pressure spring (pressure means)/244 Link mechanism (interlocking mechanism)/244A Link mechanism (releasing means)/300 Planar portion (second posture regulating portion)/301 Engagement portion/302 Concave portion (releasing means)/ 500... Motor (driving source)/601, 602... Rotating shaft/603... Fitting portion (first restricting portion)/701... Long hole portion/702... Regulating member/703・・・Regulatory mechanism (Second regulator)

Claims (14)

a device body;
an image carrier provided in the apparatus main body;
A developer bearing member capable of developing an electrostatic latent image on the image bearing member by carrying and moving the developer, and the developer bearing member are arranged with a gap therebetween. a first position where a gap between the developer carrier and the image carrier is a predetermined gap; and a first position from the first position. a developing device movably provided in the device body at a second position where the developer carrier is separated from the image carrier;
pressing means for pressing the developing device toward the image carrier in a first direction;
At the first position, the first abutting portion of the developing device pressurized in the first direction abuts, and the second direction is the direction in which the gap between the developer carrier and the image carrier is regulated. a first positioning unit that positions the direction;
a second positioning portion that abuts against a second abutting portion of the developing device pressurized in the first direction at the first position to perform positioning in a third direction that intersects with the second direction;
a first posture regulating portion that regulates the posture of the developing device moving from the second position to the first position on one end side of the developing device in the longitudinal direction intersecting the first to third directions;
a second posture regulating portion that regulates the posture of the developing device moving from the second position to the first position on the other end side in the longitudinal direction of the developing device;
A state in which the developing device moves from the second position to the first position, and the first abutting portion abuts the first positioning portion, and the second abutting portion abuts the second positioning portion. a releasing means for releasing the regulation of the second attitude regulation section;
a moving member that moves in a predetermined direction;
with
The second posture regulating portion is formed in a first region of the moving member in the predetermined direction so as to be able to engage with an engaging portion provided on the other longitudinal end side of the developing device,
The releasing means is formed in a second region that is deviated from the first region with respect to the predetermined direction of the moving member,
While the moving member is moving in the predetermined direction while the first region faces the engaging portion, the second attitude regulating portion engages with the engaging portion to maintain the attitude of the developing device. is regulated and
When the moving member moves further in the predetermined direction and the engaging portion faces the second region, the engagement between the second posture regulating portion and the engaging portion is released, and the developing device is operated. Attitude restrictions are lifted
An image forming apparatus characterized by: the second posture regulating portion is a planar portion formed along the moving direction of the developing device;
The releasing means is a recess formed so as to be recessed in a direction away from the developing device from the flat portion,
2. The image forming apparatus according to claim 1 , wherein: The pressurizing means is
provided on the moving member,
While the moving member is moving in the predetermined direction while the first region faces the engaging portion, the developing device is pressurized as the moving member moves in the predetermined direction, and the second region is moved. position to the first position;
pressurizing the developing device at the first position even when the moving member moves further in the predetermined direction and the engaging portion faces a second area outside the first area;
3. The image forming apparatus according to claim 1 , wherein: a cover that is openable and closable on the apparatus main body and covers the developing device attached to the apparatus main body in a closed state;
The moving member is moved in the predetermined direction interlocking with the operation of changing the cover from the open state to the closed state, and the moving member is moved in the opposite direction to the predetermined direction interlocking with the operation of changing the cover from the closed state to the open state. an interlocking mechanism for moving in a direction;
4. The image forming apparatus according to any one of claims 1 to 3 , characterized by: the first posture regulating portion is an elongated hole formed along the moving direction of the developing device;
At one end in the longitudinal direction of the developing device, there is provided a protrusion that fits in the elongated hole and is movable within the elongated hole when the developing device is moved.
5. The image forming apparatus according to any one of claims 1 to 4 , characterized by: a drive source for driving the developer carrier;
The drive of the drive source is input to the developing device from one end in the longitudinal direction,
6. The image forming apparatus according to any one of claims 1 to 5, characterized by: The first abutting portion and the first positioning portion are provided at two locations separated in the longitudinal direction, respectively, and perform positioning in the second direction at two points,
The second abutting portion and the second positioning portion are provided at two locations separated in the longitudinal direction, respectively, and perform positioning in the third direction at two points.
7. The image forming apparatus according to any one of claims 1 to 6 , characterized by: The angle formed by the second direction and the third direction is 90° or more and less than 180°.
8. The image forming apparatus according to any one of claims 1 to 7 , characterized by: The first direction is a direction passing between the first positioning portion and the second positioning portion,
9. The image forming apparatus according to any one of claims 1 to 8 , characterized by: The image carrier is a cylindrical photosensitive drum,
The developer carrier is a cylindrical developing sleeve,
The second direction is a direction connecting the center of the photosensitive drum and the center of the developing sleeve.
10. The image forming apparatus according to any one of claims 1 to 9 , characterized by: a device body;
an image carrier provided in the apparatus main body;
A developer bearing member capable of developing an electrostatic latent image on the image bearing member by carrying and moving the developer, and the developer bearing member are arranged with a gap therebetween. a first position where a gap between the developer carrier and the image carrier is a predetermined gap; and a first position from the first position. a developing device rotatably provided in the device main body at a second position where the developer carrier is separated from the image carrier;
pressing means for pressing the developing device toward the image carrier in a first direction;
At the first position, the abutting portion of the developing device pressurized in the first direction abuts against the second direction, which is the direction for regulating the gap between the developer carrier and the image carrier. a positioning unit for positioning;
The developing device is rotatably supported from the second position to the first position at one end of the developing device in a longitudinal direction intersecting the first direction and the second direction, and the developing device rotates. a first restricting portion that restricts movement in a direction perpendicular to the axis;
A second restricting portion that rotatably supports the developing device from the second position to the first position and restricts movement of the developing device in a direction orthogonal to a rotation axis at the other end in the longitudinal direction. When,
In a state in which the developing device moves from the second position to the first position and the abutting portion is in contact with the positioning portion, the second restricting portion restricts the direction along the second direction. and a release means for releasing,
An image forming apparatus characterized by: a drive source for driving the developer carrier;
The drive of the drive source is input to the developing device from one end in the longitudinal direction,
12. The image forming apparatus according to claim 11 , characterized by: The abutting portion and the positioning portion are provided at two locations separated in the longitudinal direction, respectively, and the positioning in the second direction is performed at two points.
13. The image forming apparatus according to claim 11 , characterized by: The image carrier is a cylindrical photosensitive drum,
The developer carrier is a cylindrical developing sleeve,
The second direction is a direction connecting the center of the photosensitive drum and the center of the developing sleeve.
14. The image forming apparatus according to any one of claims 11 to 13 , characterized by:

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