Process cartridge and image forming apparatus

The present invention relates to an image forming apparatus such as a laser printer and a process cartridge mounted on the image forming apparatus.

In a process cartridge mounted on an image forming apparatus such as a laser printer, a charger, a developing cartridge, and a transfer roller are arranged around the photosensitive drum in order according to the rotation direction of the photosensitive drum. As the photosensitive drum rotates, the surface of the photosensitive drum is first uniformly charged by a charger and then subjected to selective exposure by a laser beam. As a result, the electric charge on the surface of the photosensitive drum is partially removed, and an electrostatic latent image is formed on the surface of the photosensitive drum. Toner is contained in the developing cartridge, and the electrostatic latent image on the surface of the photosensitive drum is developed by supplying toner from the developing cartridge when facing the developing cartridge. Then, the toner image supported on the surface of the photosensitive drum faces the transfer roller and is transferred to the paper while the paper passes between the photosensitive drum and the transfer roller.

As such a process cartridge, one having a drum frame divided into an upper frame and a lower frame is known. In this process cartridge, a charger is supported on the upper frame, a photosensitive drum, a developing cartridge and a transfer roller are supported on the lower frame, and when the upper frame and the lower frame are combined, the charger is used on the photosensitive drum. Above, it is placed facing the photosensitive drum at a predetermined distance (see, for example, Patent Document 1).<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-295720</text></patcit>

<p> However, in order to uniformly charge the surface of the photosensitive drum, the positional relationship (distance) between the photosensitive drum and the charger is important. However, in the configuration of Patent Document 1, since the relative position between the photosensitive drum and the charger is determined via the upper frame and the lower frame, it is difficult to accurately position the relative position between the photosensitive drum and the charger. .. That is, since the upper frame and the lower frame each have a manufacturing error, when the upper frame and the lower frame are combined, the upper frame and the lower frame are manufactured at the relative positions of the upper frame and the lower frame, respectively. An error weighted error occurs. As a result, due to this error, it becomes difficult to accurately position the relative positions of the photosensitive drum and the charger.</p><p> If a large error occurs in the relative position between the photosensitive drum and the charger, the accuracy of uniformly charging the surface of the photosensitive drum decreases, and the quality of the image formed on the paper deteriorates.</p><p> Therefore, an object of the present invention is to form a high-quality image by providing a process cartridge capable of accurately positioning the relative position between the image carrier and the acting means such as the charging means, and the process cartridge. The purpose is to provide an image forming apparatus capable of providing an image forming apparatus.</p>

<p> In order to achieve the above object, the invention according to claim 1 supports an image carrier that supports a developer image and the image carrier in a process cartridge that is detachably attached to an image forming apparatus. A shaft, a first bearing portion that receives the shaft, a charging means for charging the image carrier, and a first frame that supports the first bearing portion and the charging means and is integrally formed. It is characterized by having.</p><p> According to such a configuration, the relative position between the image carrier and the charging means is determined by the relative position between the first bearing portion that receives the axis of the image carrier and the charging means, so that the first bearing portion and the charging means can be determined. By being supported by the common first frame, the relative positions of the image carrier and the charging means can be accurately positioned.</p><p> The invention according to claim 2 is the transfer means for transferring the second bearing portion that receives the shaft and the developer image supported on the image carrier to the transfer medium in the invention according to claim 1. It is characterized in that it is formed separately from the first frame and includes the second bearing portion and the second frame that supports the transfer means.</p><p> According to such a configuration, the relative positions of the image carrier and the charging means are irrelevant to the relative positions of the first frame and the second frame, so that when the first frame and the second frame are combined, Even if an error occurs in the relative positions of the first frame and the second frame, it is possible to maintain an accurate relative position between the image carrier and the charging means regardless of the error.</p><p> Further, since the relative position between the image carrier and the transfer means is determined by the relative position between the second bearing portion that receives the axis of the image carrier and the transfer means, the second frame in which the second bearing portion and the transfer means are common. By being supported by the image carrier, the relative position between the image carrier and the transfer means can be accurately positioned.</p><p> The invention according to claim 3 is a process cartridge that is detachably attached to an image forming apparatus, the image carrier that supports the developer image, the shaft that supports the image carrier, and the shaft. A first bearing portion that receives the shaft, a second bearing portion that receives the shaft, a plurality of acting means for exerting a predetermined action on the image carrier, the first bearing portion, and at least one said acting means. It is characterized in that it includes a first frame that supports the second bearing portion and a second frame that supports at least one of the acting means other than the second bearing portion and the acting means supported by the first frame. ..</p><p> According to such a configuration, the relative position of the image carrier and the acting means supported by the first frame is determined by the relative position of the acting means and the first bearing portion that receives the axis of the image carrier, and the image is supported. The relative position of the body and the acting means supported by the second frame is determined by the relative position of the acting means and the second bearing portion that receives the axis of the image carrier. That is, the relative positions of the image carrier and the means of action supported by the first frame and the second frame are positioned with reference to the axis of the image carrier received by the first bearing portion and the second bearing portion. Therefore, even if there is an error in the relative position between the first frame and the second frame when the first frame and the second frame are combined, the first frame that receives the axis of the image bearing together regardless of the error. The bearing portion and the second bearing portion can accurately position the relative positions of the image carrier and the acting means supported by the first frame and the second frame.</p><p> The invention according to claim 4 is the invention according to claim 3, wherein the acting means supported by the first frame includes a charging means for charging the image carrier, and the first aspect thereof. The means of action supported by the two frames is characterized by including transfer means for transferring the developer image carried on the image carrier to a transfer medium.</p><p> According to such a configuration, the relative positions of the charging means and the transfer means with respect to the image carrier can be accurately positioned.</p><p> Further, the invention according to claim 5 is characterized in that, in the invention according to any one of claims 2 to 4, the first bearing portion and the second bearing portion are the same bearing member.</p><p> According to such a configuration, since the first bearing portion and the second bearing portion are the same bearing member, the relative positions of the first frame and the second frame can be positioned via the bearing member. Therefore, the relative positions of the first frame and the second frame can be accurately positioned.</p><p> The invention according to claim 6 is a process cartridge that is detachably attached to an image forming apparatus, the image carrier that supports the developer image, the shaft that supports the image carrier, and the shaft. It is characterized in that it includes a first frame that supports the above, and a second frame that is combined with the first frame in a state of being positioned with respect to the axis.</p><p> According to such a configuration, the second frames are combined and positioned with respect to the first frame with reference to the axis of the image carrier supported by the first frame. Therefore, the relative positions of the first frame and the second frame can be accurately positioned with reference to the axis of the image carrier.</p><p> The invention according to claim 7 is characterized in that, in the invention according to claim 6, it is supported by the first frame and includes a charging means for charging the image carrier.</p><p> According to such a configuration, the relative position between the image carrier and the charging means can be accurately positioned.</p><p> The invention according to claim 8 is the transfer means for transferring the developer image supported by the second frame and supported on the image carrier to the transfer medium in the invention according to claim 6 or 7. It is characterized by having.</p><p> According to such a configuration, the relative position between the image carrier and the transfer means can be accurately positioned.</p><p> The invention according to claim 9 is the invention according to any one of claims 6 to 8, wherein the first frame includes a bearing member that receives the shaft, and the second frame includes the bearing member. It is characterized in that it is positioned with respect to the axis.</p><p> According to such a configuration, the relative positions of the first frame and the second frame can be accurately positioned via the bearing member.</p><p> Further, the invention according to claim 10 has a path for guiding the bearing member when the second frame is combined with the first frame in the invention according to claim 5 or 9. It is characterized by being.</p><p> According to such a configuration, when the first frame and the second frame are combined, the bearing member is guided to the path provided in the second frame. As a result, the first frame and the second frame can be easily combined so that their relative positions are accurately positioned.</p><p> Further, the invention according to claim 11 is the invention according to any one of claims 5, 9 and 10, wherein the bearing member is in a state where the first frame and the second frame are combined. It is characterized in that it also serves as a fixing means for fixing the bearings to each other.</p><p> According to such a configuration, the first frame and the second frame can be fixed to each other by the bearing member. Therefore, the number of parts constituting the process cartridge can be reduced and the configuration can be simplified as compared with the configuration in which the fixing means for fixing the first frame and the second frame to each other is separately provided. .. As a result, the cost of the process cartridge can be reduced.</p><p> The invention according to claim 12 is the invention according to claim 11, wherein the bearing member rotates by a predetermined angle about the axis in a state where the first frame and the second frame are combined. By allowing the first frame to be fixed to the second frame, the first frame is moved to a fixed release position for releasing the fixation of the first frame to the second frame.</p><p> According to such a configuration, the first frame and the second frame can be easily fixed to each other or released from the fixing by rotating the bearing member by a predetermined angle about the axis of the image carrier. it can. Therefore, workability can be improved.</p><p> The invention according to claim 13 is the invention according to claim 11 or 12, wherein the bearing member is provided around the shaft insertion portion through which the shaft is inserted and the shaft insertion portion, and is provided in the path. It is characterized in that it is provided with a fixed portion that can pass through the path along the path and cannot pass through the path in a state of intersecting the path.</p><p> According to such a configuration, when the first frame and the second frame are combined, the fixed portion of the bearing member is passed along the path provided in the second frame, so that the first frame and the second frame are passed. The frames can be combined so that their relative positions are accurately positioned. Further, by making the fixed portion of the bearing member intersect the path in the state where the first frame and the second frame are combined, it is possible to prevent the fixed portion from passing through the path. It is possible to prevent the first frame and the second frame from separating. That is, the first frame and the second frame can be combined in a state where their relative positions are accurately positioned via the fixed portion of the bearing member, and the combined first frame and the first frame can be combined. It can be fixed with 2 frames.</p><p> The invention according to claim 14 is the invention according to claim 13, wherein the second frame is at an end portion of the path on which the first frame and the second frame are fixed to each other. It is characterized by having a receiving portion that extends from the route in a direction intersecting the guide direction of the route and receives the fixed portion in a state of intersecting the route.</p><p> According to such a configuration, after receiving the fixed portion of the bearing member in the receiving portion of the second frame, the bearing member is rotated so that the fixed portion intersects the path, so that the fixed portion can be removed from the receiving portion. It can surely prevent the withdrawal. As a result, the first frame and the second frame can be securely fixed.</p><p> The invention according to claim 15 is the invention according to any one of claims 12 to 14, wherein the bearing member is provided around a shaft insertion portion through which the shaft is inserted and around the shaft insertion portion. In a state where the first frame and the second frame are fixed to each other, a flange portion arranged to face the second frame and a flange portion facing the second frame are formed on the second frame. It is characterized by having a locking portion for locking.</p><p> According to such a configuration, by locking the locking portion of the bearing member to the second frame, careless rotation of the bearing member can be prevented, and the first frame and the second frame carelessly move. It can be prevented from separating.</p><p> The invention according to claim 16 is characterized in that, in the invention according to claim 15, the second frame includes a locked portion to which the locking portion is locked.</p><p> According to such a configuration, by locking the locking portion of the bearing member to the locked portion of the second frame, careless rotation of the bearing member can be reliably prevented.</p><p> The invention according to claim 17 is the invention according to claim 15 or 16, wherein the flange portion can move in a direction in which the locking portion contacts or separates from the second frame. It is characterized in that a hole for bending the flange portion is formed.</p><p> According to such a configuration, when the locking portion is engaged with and disengaged from the second frame, the bearing member can be rotated while bending the flange portion. Therefore, it is possible to facilitate the engagement and disengagement of the locking portion with respect to the second frame.</p><p> The invention according to claim 18 is characterized in that the image forming apparatus includes the process cartridge according to any one of claims 1 to 17.</p><p> According to such a configuration, since the process cartridge capable of accurately positioning the relative position between the image carrier and the charging means is provided, the image carrier can be uniformly charged by the charging means, and a high-quality image can be obtained. Can be formed.</p>

<p> According to the invention of claim 1, the relative positions of the image carrier and the charging means can be accurately positioned.</p><p> According to the second aspect of the present invention, the relative positions of the charging means and the transferring means with respect to the image carrier can be accurately positioned.</p><p> According to the third aspect of the present invention, the relative positions of the image carrier and the means of operation supported by the first frame and the second frame can be accurately positioned.</p><p> According to the invention of claim 4, the relative positions of the charging means and the transferring means with respect to the image carrier can be accurately positioned.</p><p> According to the invention of claim 5, the relative positions of the first frame and the second frame can be accurately positioned via the bearing member.</p><p> According to the invention of claim 6, the relative positions of the first frame and the second frame can be accurately positioned with reference to the axis of the image carrier.</p><p> According to the invention of claim 7, the relative positions of the image carrier and the charging means can be accurately positioned.</p><p> According to the invention of claim 8, the relative position between the image carrier and the transfer means can be accurately positioned.</p><p> According to the invention of claim 9, the relative positions of the first frame and the second frame can be accurately positioned via the bearing member.</p><p> According to the invention of claim 10, the first frame and the second frame can be easily combined in a state where the relative positions are accurately positioned.</p><p> According to the invention of claim 11, the cost of the process cartridge can be reduced.</p><p> According to the invention of claim 12, the first frame and the second frame can be easily fixed to each other or released from the fixing, and workability can be improved.</p><p> According to the invention of claim 13, the first frame and the second frame can be combined in a state where their relative positions are accurately positioned via the fixing portion of the bearing member. The combined first frame and second frame can be fixed.</p><p> According to the invention of claim 14, the first frame and the second frame can be reliably fixed.</p><p> According to the invention of claim 15, it is possible to prevent the first frame and the second frame from being inadvertently separated.</p><p> According to the invention of claim 16, careless rotation of the bearing member can be reliably prevented.</p><p> According to the invention of claim 17, it is possible to facilitate the engagement and disengagement of the locking portion with respect to the second frame.</p><p> According to the invention of claim 18, a high quality image can be formed.</p>

1 and 2 are cross-sectional views of a main part showing an embodiment of a laser printer as an image forming apparatus of the present invention. The laser printer 1 is used to form an image on the main body casing 2, the feeder unit 4 for feeding the paper 3 as a transfer medium, and the fed paper 3 housed in the main body casing 2. It is equipped with an image forming unit 5 and the like.

An attachment / detachment port 6 for attaching / detaching the process cartridge 20, which will be described later, is formed on the side wall on one side of the main body casing 2, and a front cover 7 for opening / closing the attachment / detachment opening 6 is provided. The front cover 7 is rotatably supported by a cover shaft (not shown) inserted through the lower end thereof. As a result, when the front cover 7 is closed with the cover shaft as the center, the attachment / detachment port 6 is closed by the front cover 7, and when the front cover 7 is opened with the cover shaft as the fulcrum (tilted), as shown in FIG. As shown in FIG. 2, the attachment / detachment port 6 is opened, and the process cartridge 20 can be attached / detached to / from the main body casing 2 through the attachment / detachment port 6.

In the following description, in the laser printer 1 and the process cartridge 20 described later, when the process cartridge 20 is mounted on the main body casing 2, the side on which the front cover 7 is provided is referred to as the "front side", and the opposite side is referred to as the "front side". Let it be "rear side".

The feeder unit 4 has a paper feed tray 9 detachably mounted on the bottom of the main body casing 2, a paper feed roller 10 and a paper pad 11 provided above the front end of the paper feed tray 9, and paper feed. A pickup roller 12 provided on the rear side of the roller 10, a pinch roller 13 arranged to face each other on the lower front side of the paper feed roller 10, and a paper dust removing roller 8 arranged to face each other on the upper front side of the paper feed roller 10. It is provided with a registration roller 14 provided above the rear side of the paper roller 10.

Inside the paper feed tray 9, a paper pressing plate 15 on which the paper 3 can be placed in a stacked manner is provided. The paper pressing plate 15 is swingably supported at the rear end portion, so that the front end portion is arranged downward, and the mounting position along the bottom plate 16 of the paper feed tray 9 and the front end portion are arranged upward. It is possible to swing to a tilted transport position.

Further, a lever 17 for lifting the front end portion of the paper pressing plate 15 upward is provided at the front end portion of the paper feed tray 9. The lever 17 is formed in a substantially L-shaped cross section so as to wrap around from the front side to the lower side of the paper pressing plate 15, and its upper end is attached to a lever shaft 18 provided at the front end of the paper feed tray 9. The rear end is in contact with the front end of the lower surface of the paper pressing plate 15. As a result, when a clockwise rotational driving force is input to the lever shaft 18, the lever 17 rotates with the lever shaft 18 as a fulcrum, and the rear end of the lever 17 lifts the front end of the paper pressing plate 15. The paper pressing plate 15 is positioned at the transport position.

When the paper pressing plate 15 is positioned at the transport position, the paper 3 on the paper pressing plate 15 is pressed by the pickup roller 12, and the rotation of the pickup roller 12 causes the paper 3 between the paper feed roller 10 and the paper feed pad 11. Transport is started toward.

On the other hand, when the paper feed tray 9 is separated from the main body casing 2, the front end of the paper pressing plate 15 moves downward due to its own weight, and the paper pressing plate 15 is positioned at the mounting position. When the paper pressing plate 15 is positioned at the mounting position, the paper 3 can be stacked on the paper pressing plate 15.

The paper 3 fed by the pickup roller 12 toward the paper feed roller 10 and the paper feed pad 11 is sandwiched between the paper feed roller 10 and the paper feed pad 11 by the rotation of the paper feed roller 10. Occasionally, each sheet is surely separated and fed. The paper 3 that has been fed passes between the paper feed roller 10 and the pinch roller 13, and is conveyed to the resist roller 14 after the paper dust is removed by the paper dust removing roller 8.

The resist roller 14 is composed of a pair of rollers, and transfers the paper 3 between the photosensitive drum 29 and the transfer roller 32, which will be described later, to transfer the toner image on the photosensitive drum 29 to the paper 3 after the resist. Transport to position.

The image forming unit 5 includes a scanner unit 19, a process cartridge 20, a fixing unit 21, and the like.

The scanner unit 19 is provided in the upper part of the main body casing 2 and includes a laser light source (not shown), a rotationally driven polygon mirror 22, an fθ lens 23, a reflector 24, a lens 25, a reflector 26, and the like. As shown by the chain line, the laser beam based on the image data emitted from the laser light source is deflected by the polygon mirror 22 and passes through the fθ lens 23, then the optical path is folded back by the reflector 24 and further passes through the lens 25. After that, the optical path is further bent downward by the reflecting mirror 26, so that the surface of the photosensitive drum 29 described later of the process cartridge 20 is irradiated.

The process cartridge 20 is detachably attached to the main body casing 2 below the scanner unit 19. As shown in FIG. 10, the process cartridge 20 is formed as a housing, an upper frame 27 as a first frame, and a lower frame 27 as a second frame, which is formed separately from the upper frame 27 and combined with the upper frame 27. It has a frame 28. Further, as shown in FIG. 6, the process cartridge 20 includes a photosensitive drum 29 as an image carrier, a scorotron type charger 30 as a charging means, a developing cartridge 31, a transfer roller 32 as a transfer means, and a transfer roller 32 as a transfer means. Equipped with a cleaning brush 33.

The photosensitive drum 29 has a cylindrical shape, and the outermost layer is a drum body 34 formed of a positively charged photosensitive layer made of polycarbonate or the like, and at the axial center of the drum body 34, along the longitudinal direction of the drum body 34. It is equipped with a metal drum shaft 35 as an extending shaft. The drum shaft 35 is supported by the upper frame 27, and the drum body 34 is rotatably supported with respect to the drum shaft 35, so that the photosensitive drum 29 can rotate around the drum shaft 35 in the upper frame 27. It is provided.

The scorotron type charger 30 is supported by the upper frame 27, and is arranged diagonally above the rear side of the photosensitive drum 29 so as to face the photosensitive drum 29 at a predetermined interval so as not to come into contact with the photosensitive drum 29. The scorotron type charger 30 is provided between the discharge wire 37 and the discharge wire 37 and the photosensitive drum 29, which are arranged so as to face each other in the axial direction of the photosensitive drum 29 at predetermined intervals, and the discharge wire 37 to the photosensitive drum 29 are provided. It is equipped with a grid 38 for controlling the amount of discharge to. In this scorotron type charger 30, a bias voltage is applied to the grid 38, and at the same time, a high voltage is applied to the discharge wire 37 to discharge the discharge wire 37 into a corona discharge, whereby the surface of the photosensitive drum 29 is uniformly positive. Can be charged.

The scorotron type charger 30 is provided with a cleaning member 36 for cleaning the discharge wire 37 so as to sandwich the discharge wire 37.

The developing cartridge 31 is formed in a box shape with the rear side open, and is detachably attached to the lower frame 28. A toner accommodating chamber 39, a supply roller 40, a developing roller 41, and a layer thickness regulating blade 42 are provided in the developing cartridge 31.

The toner storage chamber 39 is formed as an internal space on the front side of the developing cartridge 31 partitioned by the partition plate 43. The toner storage chamber 39 is filled with a positively charged non-magnetic one-component toner as a developing agent. Examples of this toner include polymerizable monomers, for example, styrene-based monomers such as styrene, and acrylic monomers such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. , A polymerized toner obtained by copolymerizing by suspension polymerization or the like is used. Such a polymerized toner has a substantially spherical shape, has extremely good fluidity, and can achieve high-quality image formation.

A colorant such as carbon black, wax, or the like is blended in such toner, and an external additive such as silica is added in order to improve the fluidity. The average particle size of the toner is about 6 to 10 μm.

Further, an agitator 44 is provided in the toner storage chamber 39. The toner in the toner storage chamber 39 is agitated by the agitator 44 and discharged from the opening 45 which communicates in the front-rear direction below the partition plate 43 toward the supply roller 40.

The feed roller 40 is located behind the opening 45 and is rotatably supported by the developing cartridge 31. The supply roller 40 is configured by coating a metal roller shaft with a roller made of a conductive foam material. The supply roller 40 is rotationally driven by the input of power from a motor (not shown).

The developing roller 41 is rotatably supported by the developing cartridge 31 on the rear side of the supply roller 40 in a state of being in contact with the supply roller 40 so as to be compressed with each other. Further, the developing roller 41 comes into contact with the photosensitive drum 29 in a state where the developing cartridge 31 is mounted on the lower frame 28. The developing roller 41 is configured by coating a metal roller shaft 96 with a roller made of a conductive rubber material. At the front end of the developing cartridge 31, the roller shaft 96 has both ends protruding outward from the side surface of the developing cartridge 31 in the width direction orthogonal to the front-rear direction (see FIGS. 3 and 4). In the roller of the developing roller 41, the surface of the roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles or the like is coated with a coating layer of urethane rubber or silicone rubber containing fluorine. A development bias is applied to the development roller 41 during development. Further, the developing roller 41 is rotationally driven in the same direction as the supply roller 40 by inputting power from a motor (not shown).

The layer thickness regulating blade 42 includes a pressing portion 47 having a semicircular cross section made of insulating silicone rubber at the tip of a blade main body 46 made of a metal leaf spring material. The layer thickness regulating blade 42 is supported by the developing cartridge 31 above the developing roller 41, and the pressing portion 47 is pressed onto the developing roller 41 by the elastic force of the blade body 46.

The toner discharged from the opening 45 is supplied to the developing roller 41 by the rotation of the supply roller 40, and at this time, the toner is positively triboelectricly charged between the supply roller 40 and the developing roller 41. The toner supplied onto the developing roller 41 enters between the pressing portion 47 of the layer thickness regulating blade 42 and the developing roller 41 as the developing roller 41 rotates, and the developing roller 41 forms a thin layer having a constant thickness. Supported on top.

The transfer roller 32 is rotatably supported by the lower frame 28, and in a state where the upper frame 27 and the lower frame 28 are combined, they come into contact with the photosensitive drum 29 in the vertical direction so as to face each other and contact the photosensitive drum 29. It is arranged so as to form a nip between them. The transfer roller 32 is configured by coating a metal roller shaft 108 with a roller made of a conductive rubber material. A transfer bias is applied to the transfer roller 32 during transfer. Further, the transfer roller 32 is rotationally driven in the direction opposite to that of the photosensitive drum 29 by inputting power from a motor (not shown).

The cleaning brush 33 is attached to the lower frame 28, and is arranged so as to face the photosensitive drum 29 on the rear side of the photosensitive drum 29 in a state where the upper frame 27 and the lower frame 28 are combined. ing.

The surface of the photosensitive drum 29 is first uniformly positively charged by the scorotron type charger 30 as the photosensitive drum 29 rotates, and then exposed by high-speed scanning of a laser beam from the scanner unit 19, and the paper 3 An electrostatic latent image corresponding to the image to be formed is formed.

Next, due to the rotation of the developing roller 41, when the toner carried and positively charged on the developing roller 41 comes into contact with the photosensitive drum 29 facing the photosensitive drum 29, the static electricity formed on the surface of the photosensitive drum 29 is formed. It is supplied to a latent image, that is, an exposed portion of the surface of the photosensitive drum 29 that is uniformly positively charged and whose potential is lowered by being exposed by the laser beam. As a result, the electrostatic latent image of the photosensitive drum 29 is visualized, and the toner image by reverse development is supported on the surface of the photosensitive drum 29.

After that, in the toner image supported on the surface of the photosensitive drum 29, as shown in FIG. 1, the paper 3 conveyed by the resist roller 14 passes through the transfer position between the photosensitive drum 29 and the transfer roller 32. In the meantime, it is transferred to the paper 3 by the transfer bias applied to the transfer roller 32. The paper 3 on which the toner image is transferred is conveyed to the fixing unit 21.

The transfer residual toner remaining on the photosensitive drum 29 after transfer is collected by the developing roller 41. Further, the paper dust from the paper 3 adhering to the photosensitive drum 29 after the transfer is collected by the cleaning brush 33.

The fixing portion 21 is provided on the rear side of the process cartridge 20, and includes a fixing frame 48 and a heating roller 49 and a pressure roller 50 in the fixing frame 48.

The heating roller 49 includes a metal base tube and a halogen lamp for heating in the metal base tube, and is rotationally driven by input of power from a motor (not shown).

The pressurizing roller 50 is arranged below the heating roller 49 so as to press the heating roller 49. The pressure roller 50 is configured by coating a metal roller shaft with a roller made of a rubber material, and is driven by the rotational drive of the heating roller 49.

In the fixing section 21, the toner transferred onto the paper 3 at the transfer position is heat-fixed while the paper 3 passes between the heating roller 49 and the pressure roller 50. The paper 3 to which the toner is fixed is conveyed to the paper ejection path 51 extending in the vertical direction toward the upper surface of the main body casing 2. The paper 3 conveyed to the paper ejection path 51 is ejected onto the paper ejection tray 53 formed on the upper surface of the main body casing 2 by the paper ejection roller 52 provided on the upper side thereof.

FIG. 3 is a plan view of the process cartridge 20, and FIG. 4 is a side view of the process cartridge 20. Further, FIG. 5 is a cross-sectional view taken along the cutting line AA shown in FIG. 3, and FIG. 6 is a cross-sectional view taken along the cutting line BB shown in FIG.

As shown in FIG. 3, the upper frame 27 integrally includes a left side wall 54, a right side wall 55, and an upper wall 56, and as shown in FIG. 6, the front and the lower side are open.

As shown in FIG. 5, the left side wall 54 faces the drum body 34 from one side in the width direction orthogonal to the front-rear direction (hereinafter, one side in the width direction is the left side and the other side in the width direction is the right side). The side plate portion 57, the extension plate portion 58 extending from the upper end edge of the lower left side plate portion 57 toward the right side and covering the drum gear 81 described later from above, and the extension plate portion 58 extending upward from the right end edge of the extension plate portion 58, the upper left It is equipped with a side plate portion 59 (see FIG. 10).

A drum shaft 35 is inserted through the lower left side plate portion 57, and a left support hole 60 into which a bearing member 66 as a first bearing portion and a second bearing portion, which will be described later, is fitted is formed. Further, the lower left plate portion 57 has a spacer portion 200 for supporting the flange portion 69 of the bearing member 66, which will be described later, with a slight gap in the left-right direction from the lower left plate portion 57 around the left support hole 60. , It is formed so as to protrude outward on the left side.

As shown in FIG. 4, the upper left plate portion 59 has a wire electrode 61 for supplying power to the discharge wire 37 of the scorotron type charger 30 on the front side thereof, and a grid 38 of the scorotron type charger 30 on the rear side thereof. A grid electrode 62 for supplying power to the wire is embedded. The upper end edge of the upper left side plate portion 59 is formed by a horizontal portion extending substantially horizontally in the front-rear direction and an inclined portion extending diagonally downward from the rear end of the horizontal portion.

As shown in FIG. 5, the right side wall 55 is formed in a flat plate shape and faces the drum body 34 from the right side. The upper end edge of the right side wall 55 extends substantially horizontally in the front-rear direction corresponding to the upper end edge of the upper left side plate portion 59, and a horizontal portion facing each other with the horizontal portion of the upper end edge of the upper left side plate portion 59 and this horizontal portion. It extends diagonally downward from the rear end and is formed by an inclined portion of the upper end edge of the upper left side plate portion 59 and an inclined portion facing each other. Further, the right side support hole 63 into which the drum shaft 35 is inserted through the right side wall 55 and the bearing member 67 as the first bearing portion and the second bearing portion, which will be described later, is fitted, becomes the left support hole 60 of the lower left side plate portion 57. They are formed at positions facing each other. Further, on the right side wall 55, a spacer part 201 for supporting the flange part 69 of the bearing member 67, which will be described later, with a slight gap in the left-right direction from the right side wall 55 around the support hole 63 is provided on the right side outside. It is formed so as to protrude into.

As shown in FIG. 3, the upper wall 56 includes an upper horizontal portion 64 and an upper inclined portion 65.

The upper horizontal portion 64 is erected between the horizontal portion of the upper end edge of the upper left side plate portion 59 and the horizontal portion of the upper end edge of the right side wall 55. The upper horizontal portion 64 is arranged above the photosensitive drum 29. Further, a laser incident window 641 for incident a laser beam scanned at high speed from the scanner unit 19 is opened in the upper horizontal portion 64 in a substantially rectangular shape in a plan view.

The upper inclined portion 65 is erected between the inclined portion of the upper end edge of the upper left side plate portion 59 and the inclined portion of the upper end edge of the right side wall 55. The upper inclined portion 65 is arranged obliquely upward on the rear side of the photosensitive drum 29 at a predetermined distance from the upper horizontal portion 64 in the front-rear direction.

A scorotron type charger 30 is provided between the upper horizontal portion 64 and the upper inclined portion 65. That is, the discharge wire 37 is stretched between the upper horizontal portion 64 and the upper inclined portion 65 and between the lower left side plate portion 57 and the right side wall 55, and the grid 38 is extended between the upper horizontal portion 64 and the upper inclined portion 65. It is erected between the lower left side plate portion 57 and the right side wall 55 between the portions 65. Further, the wire support portion 36 is arranged between the upper horizontal portion 64 and the upper inclined portion 65, and is provided so as to be movable in the left-right direction while holding the discharge wire 37 (see FIG. 6).

Further, between the lower left side plate portion 57 and the right side wall 55, the drum shaft 35 of the photosensitive drum 29 is supported via bearing members 66 and 67 arranged on the left and right.

Each bearing member 66,67 is formed of a resin material such as POM (polyacetal) resin, ABS (acrylonitrile-butadiene-styrene) resin or PS (polystyrene) resin, as shown in FIGS. 7, 8 and 9. The shaft insertion portion 68, the flange portion 69, and the fixing portion 70 are integrally provided.

The shaft insertion portion 68 has an inner diameter substantially the same as the outer diameter of the drum shaft 35, and is formed in a cylindrical shape that fits the outer peripheral surface of the drum shaft 35.

The flange portion 69 is formed in a disk shape protruding in a direction orthogonal to the axial direction from one end edge in the axial direction of the shaft insertion portion 68. Two jig holes 71 are formed in the flange portion 69 at symmetrical positions with respect to the shaft insertion portion 68. Further, on the surface of the flange portion 69 on the side where the shaft insertion portion 68 extends, two flat columnar locking projections 72 are formed at symmetrical positions with the shaft insertion portion 68 in between. Has been done. The facing directions of the two locking projections 72 are orthogonal to the facing directions of the two jig holes 71. Further, in the flange portion 69, an arcuate elongated hole 73 centered on the central axis of the shaft insertion portion 68 is formed between each of the shaft insertion portion 68 and the two locking projections 72. The elongated hole 73 allows the flange portion 69 to be bent so that the locking projection 72 moves along the axial direction of the shaft insertion portion 68.

The fixing portion 70 is formed so as to project shorter than the shaft insertion portion 68 around the shaft insertion portion 68 on the surface of the flange portion 69 on the side where the shaft insertion portion 68 extends. As shown in FIG. 9, the fixing portion 70 is formed so as to bulge from the shaft insertion portion 68 in the direction facing the locking projection 72, and the shaft insertion portion 68 is formed in the direction facing the jig hole 71. From the outer diameter of the shaft insertion portion 68 in the opposite direction of the locking projections 72 (the direction orthogonal to the opposite direction of the jig hole 71) with the pair of flat side surfaces 74, 75 facing each other with the same interval as the outer diameter. Also has a pair of arcuate curved sides 76,77 facing each other at large intervals.

As shown in FIG. 5, the bearing member 66 on the left side is attached to the lower left plate portion 57 by fitting the shaft insertion portion 68 into the left support hole 60 from the left side of the lower left plate portion 57. In this state, the flange portion 69 of the bearing member 67 on the left side is in contact with the spacer portion 200, and a slight gap is separated between the flange portion 69 and the lower left side plate portion 57. The bearing member 67 on the right side is attached to the right wall 55 by fitting the shaft insertion portion 68 into the right support hole 63 from the right side of the right wall 55. In this state, the flange portion 69 of the bearing member 67 is in contact with the spacer portion 201, and a slight gap is separated between the flange portion 69 and the right side wall 55.

Then, the shaft end portions of the drum shaft 35 are inserted into the shaft insertion portions 68 of the left and right bearing members 66 and 67 so as to be bearing, respectively, and the stop member 78 is externally fitted to the drum shaft 35. , The drum shaft 35 is supported by the left side wall 54 and the right side wall 55 via bearing members 66,67, respectively.

Both ends of the drum shaft 35 project outward from the bearing members 66 and 67 in the left-right direction, and the process cartridge 20 is attached to the main body casing 2 at the ends of the drum shaft 35 protruding from the bearing member 66 on the left side. A ground (not shown) provided on the main body casing 2 for grounding the drum shaft 35 is connected to the ground.

Further, the drum shaft 35 has two flange members 79 and 80 provided at both ends in the axial direction of the drum shaft 35 and a drum gear 81 provided at the left end in the axial direction of the drum shaft 35 between the bearing members 66 and 67. Is inserted so as to be relatively rotatable, and the drum body 34 is supported so as to be relatively rotatable via the flange members 79 and 80.

Each of the flange members 79 and 80 is formed of an insulating resin material, and is mounted on the left end portion and the right end portion of the drum body 34 so as not to rotate relative to the drum body 34, respectively. Each of the flange members 79 and 80 includes a flange bearing portion 82 into which the drum shaft 35 is inserted, an insertion portion 83 inserted into the drum body 34, and a flange connecting portion 84 connecting the flange bearing portion 82 and the insertion portion 83. Is integrally provided.

The flange bearing portion 82 has an inner diameter substantially the same as the outer diameter of the drum shaft 35, and is formed in a cylindrical shape that fits the outer peripheral surface of the drum shaft 35.

The insertion portion 83 has an outer diameter substantially the same as the inner diameter of the drum main body 34, and is formed in a cylindrical shape to be inserted into the inner peripheral surface of the drum main body 34.

The flange connecting portion 84 is formed in a ring plate shape so as to extend between the flange bearing portion 82 and the insertion portion 83 in the radial direction of the drum main body 34.

The flange member 79 on the left side is integrally formed with a flange-side coupling portion 85 for coupling with the drum gear 81 described below and an output gear 86 for engaging with the transfer gear 112 described later.

The flange-side connecting portion 85 is formed so as to project from the middle of the flange connecting portion 84 in the radial direction toward the left side.

The output gear 86 has a cylindrical shape that continuously extends to the left from the insertion portion 83, and includes a plurality of external teeth that protrude outward in the radial direction in mesh with the transfer gear 112 described later.

The drum gear 81 is provided on the left side of the flange member 79 on the left side, and has a gear bearing portion 87 into which the drum shaft 35 is inserted, an input gear 88 in which a drive transmission gear (not shown) meshes, and a gear bearing portion 87 and an input gear. The gear connecting portion 89 that connects the 88 is integrally molded.

The gear bearing portion 87 has an inner diameter substantially the same as the outer diameter of the drum shaft 35, and is formed in a tubular shape that fits the outer peripheral surface of the drum shaft 35.

The input gear 88 is formed in a cylindrical shape and includes a plurality of external teeth protruding outward in the radial direction that mesh with a drive transmission gear (not shown).

The gear connecting portion 89 is formed in a ring plate shape so as to extend between the gear bearing portion 87 and the input gear 88 in the radial direction.

Further, the gear connecting portion 89 has a gear connecting portion 90 that protrudes from the middle of the gear connecting portion 89 in the radial direction toward the right side and is for coupling with the flange side coupling portion 85 of the flange member 79 on the left side. It is formed integrally with 89.

In this drum gear 81, the gear side coupling portion 90 and the flange side coupling portion 85 of the left flange member 79 are butted so that the gear bearing portion 87 and the flange bearing portion 82 of the left flange member 79 face each other in the axial direction. By bonding and fixing, it is joined to the flange member 79 on the left side so as not to rotate relative to each other.

The drum gear 81 may be integrally formed with the flange member 79 on the left side.

Then, the left flange member 79 and the drum gear 81 insert the drum shaft 35 into the flange bearing portion 82 and the gear bearing portion 87, and press-fit the insertion portion 83 through the left end opening of the drum main body 34 to form the drum main body 34. It is attached to the left end so that it cannot rotate relative to each other.

Further, the right flange member 80 is mounted on the right end portion of the drum body 34 so as not to rotate relative to the right end portion of the drum body 34 by inserting the drum shaft 35 into the flange bearing portion 82 and press-fitting the insertion portion 83 from the right end opening of the drum body 34. ing.

By such mounting, the flange members 79 and 80 are mounted on both ends of the drum body 34 in the axial direction so as to be relatively non-rotatable, while being supported so as to be relatively rotatable with respect to the drum shaft 35. The 29 is rotatably supported by the drum shaft 35 via the respective flange members 79 and 80.

The right wall 55 facing the right flange member 80 has a spring receiving member 91 through which the drum shaft 35 is inserted between the right flange member 80 and a spring 202 received by the spring receiving member 91. It is provided.

The spring receiving member 91 has a substantially U-shaped cross section that opens toward the left side, and is supported inside the right side wall 55. Further, the spring 202 is provided around the drum shaft 35, and in a state of being received by the spring receiving member 91, the flange member 80 is urged toward the left side. As a result, the drum gear 81 joined to the left flange member 79 is brought into contact with the lower left plate portion 57 of the left wall 54, and the photosensitive drum 29 is positioned in the axial direction.

Then, when a driving force is transmitted from a motor (not shown) provided in the main body casing 2 to a drive transmission gear (not shown), the input gear 88 that meshes with the drive transmission gear is rotationally driven, whereby the photosensitive drum 29 is moved. It is rotated.

The lower frame 28 integrates a pair of side walls 92 (see FIG. 5), a rear connecting portion 93 connecting the lower end lines of the side walls 92, a front lower connecting portion 94, and a rear lower connecting portion 95 (see FIG. 6). It is formed so that the upper part is open in preparation for the purpose .

As shown in FIG. 5, the pair of side walls 92 are arranged so as to face each other with the upper frame 27 and the developing cartridge 31 (see FIG. 4) in the left-right direction. As shown in FIGS. 4 and 10, these side walls 92 guide the end of the roller shaft 96 of the developing roller 41 protruding outward in the left-right direction from the side surface of the developing cartridge 31 when the developing cartridge 31 is attached or detached. The roller shaft guide portion 97, the roller bearing inlet 98 provided at the rear end of the roller shaft guide 97 and receiving the end of the roller shaft 96 guided by the roller shaft guide 97, and the rear side of the roller bearing insert 98. In the bearing member guide portion 99 as a path for guiding the fixed portions 70 of the bearing members 66 and 67 when the upper frame 27 is attached and detached, and the bearing member guide portion 99 provided at the lower end of the bearing member guide portion 99 and guided by the bearing member guide portion 99. It is provided with a bearing member receiving portion 100 as a receiving portion for receiving the fixing portion 70.

The roller shaft guide portion 97 is formed as an upper end edge of a central portion in the front-rear direction of each side wall 92. The roller shaft guide portion 97 is formed so as to extend diagonally downward from the front side to the rear side and then extend in a substantially horizontal direction.

The roller bearing insertion portion 98 is continuous with the rear side of the roller shaft guide portion 97 on each side wall 92, and protrudes upward from the rear end portion of the roller shaft guide portion 97 to the protruding portion 101, and the front end edge of the protruding portion 101. It is formed by cutting out in a substantially rectangular shape when viewed from the side, and its lower end edge is continuous with the rear end edge of the roller shaft guide portion 97.

The front side of the roller bearing insertion portion 98 is a mounting space for mounting the development cartridge 31, and the end portion of the roller shaft 96 protruding from the side surface of the development cartridge 31 is attached to the roller shaft guide portion 97. Guided and moved toward the roller bearing inlet 98, the end of the roller shaft 96 is received by the roller bearing inlet 98, so that the roller shaft 96 is supported by a pair of side walls 92, and the development cartridge 31 Is mounted in the mounting space.

When the developing cartridge 31 is mounted on the lower frame 28, the end of the roller shaft 96 is exposed outward in the width direction of each side wall 92 via the roller bearing insertion portion 98 (see FIG. 3). When the process cartridge 20 is mounted on the main body casing 2, an electrode for applying a development bias is connected to the left end of the roller shaft 96.

The bearing member guide portion 99 is formed in the protruding portion 101 of each side wall 92 as a side view substantially U-shaped groove extending downward from the upper end edge thereof in the vertical direction and opening the upper end line. The width of the bearing member guide portion 99 in the front-rear direction is formed to be substantially the same as the distance between the flat side surfaces 74 and 75 of the fixed portions 70 of the bearing members 66 and 67. As a result, in the bearing member guide portion 99, when the flat side surfaces 74 and 75 of the fixed portion 70 are along the guide direction (vertical direction) of the bearing member guide portion 99, the fixed portion 70 is passed through and the fixed portion 70 is passed. In a state where the flat side surfaces 74 and 75 of the above intersect in the guiding direction of the bearing member guide portion 99, the passage of the fixing portion 70 is blocked.

The bearing member receiving portion 100 is formed at the lower end portion of the bearing member guide portion 99 so as to extend from the bearing member guide portion 99 in a circular shape in a side view. The inner peripheral surface of the bearing member receiving portion 100 is formed so that the diameter of the inner peripheral surface thereof is substantially the same as the distance between the curved side surfaces 76, 77 in the fixed portion 70 of the bearing member 66, 67, and the inner peripheral surface thereof. The curvature of the surface is formed to be almost the same as the curvature of each curved side surface 76,77. As a result, in the bearing member receiving portion 100, the fixing portions 70 of the bearing members 66 and 67 guided to the bearing member guide portion 99 are rotatably received.

Further, the outer surfaces of the side walls 92 in the left-right direction face each other in the front-rear direction with the bearing member receiving portion 100 interposed therebetween at the same interval as the interval between the two locking projections 72 of the bearing members 66 and 67. Two locking recesses 102 are formed at the bearing positions (symmetrical positions) as locked portions that are recessed from the outside in a substantially rectangular shape in a plan view. Further, the outer surface of each side wall 92 is recessed below the bearing member receiving portion 100 in a substantially rectangular shape in a plan view from the outer surface where the locking projection 72 is received when the bearing member receiving portion 100 receives the fixing portion 70. A bearing recess 103 is formed.

Further, on the left side wall 92, an opening 111 for exposing the transfer electrode 113, which will be described later, is formed below the bearing member receiving portion 100.

Further, on the left side wall 92, a cleaning electrode 104 for applying a cleaning bias to the cleaning brush 33 is provided behind the bearing member receiving portion 100.

As shown in FIG. 6, the rear connecting portion 93 connects between the rear ends of a pair of side walls 92. A facing wall portion 105 facing the rear side of the photosensitive drum 29 is erected on the rear connecting portion 93, and a cleaning brush 33 is attached to the facing wall portion 105.

The front lower connecting portion 94 connects between the lower end edge front portions of the pair of side wall 92s. The front lower connecting portion 94 includes a resist roller accommodating portion 106 accommodating one (upper side) resist roller 14.

As shown in FIG. 4, the rear lower connecting portion 95 connects the lower end edge rear portion of the pair of side wall 92s below the bearing member receiving portion 100. As shown in FIG. 6, the lower connecting portion 95 is provided with a transfer roller accommodating portion 107 accommodating the transfer roller 32. Further, as shown in FIG. 5, the rear lower connecting portion 95 is provided with roller bearings 109 that receive both ends of the roller shaft 108 of the transfer roller 32 at both ends in the width direction of the transfer roller accommodating portion 107.

The transfer roller 32 is rotatably supported by the rear lower connecting portion 95 by receiving both ends of the roller shaft 108 by the roller bearing 109.

Further, the roller shaft 108 of the transfer roller 32 protrudes outward from the roller bearing 109 in the left-right direction, and cover members 110 formed of an insulating resin material are attached to both of the protruding ends. ing. As a result, the roller shaft 108 is prevented from being exposed near both ends in the left-right direction of the drum body 34, and discharge from the roller shaft 108 to the drum body 34 can be prevented when a transfer bias is applied.

Further, the left end portion of the roller shaft 108 is coated with a transfer electrode 113 for applying a transfer bias. The transfer electrode 113 is exposed outward on the left side through the hole 111 of the side wall 92 on the left side.

Further, a transfer gear 112 is mounted between the cover member 110 and the transfer electrode 113 on the roller shaft 108 so as not to rotate relative to each other. The transfer gear 112 includes a plurality of external teeth protruding outward in the radial direction that mesh with the output gear 86 of the flange member 79 on the left side. As a result, when the photosensitive drum 29 is rotated by a driving force from a motor (not shown) provided in the main body casing 2, the output gear 86 of the left flange member 79 mounted on the photosensitive drum 29 is rotated. , The transfer gear 112 that meshes with the output gear 86 is rotationally driven, and the transfer roller 32 is rotated.

Then, in this process cartridge 20, as shown in FIG. 10, the upper frame 27 is assembled to the lower frame 28 from above. At this time, as shown in FIG. 11A, first, the bearing members 66, 67 are first, and the flat side surfaces 74, 75 of the fixing portion 70 are the guiding directions (vertical direction) of the bearing member guide portion 99 of the lower frame 28. Then, as shown in FIG. 11B, the fixing portion 70 is inserted into the bearing member guide portion 99 from above. Then, the fixing portion 70 is guided by the bearing member guide portion 99 and is moved toward the bearing member receiving portion 100. Then, when the fixing portion 70 is accepted by the bearing member receiving portion 100, there is a gap between the flange portion 69 of the left bearing member 66 and the left wall 54 and a gap between the flange portion 69 of the bearing member 67 and the right wall 55. , Each side wall 92 of the lower frame 28 is sandwiched (see FIG. 5), and the inner surface of the flange portion 69 (the surface on the side where the shaft insertion portion 68 extends) of each bearing member 66, 67 is the side wall 92. It faces the outer side surface and comes into close contact.

Immediately after the fixing portion 70 is received by the bearing member receiving portion 100, the locking projection 72 located below is received by the receiving recess 103 formed in the side wall 92. After that, a jig (not shown) is inserted into the jig hole 71 of the flange portion 69, and the flange portion 69 is bent by this jig so that the locking projection 72 is separated from the side wall 92, and each bearing is bent. The members 66 and 67 are rotated about 90 degrees around the drum shaft 35. Then, as shown in FIG. 11 (c), each locking projection 72 formed on the inner surface of the flange portion 69 faces each locking recess 102 formed on the outer surface of the side wall 92, and then heals. When the jig is removed from the tool hole 71, the flange portion 69 is restored to be in close contact with the side wall 92, and each locking projection 72 is fitted into each locking recess 102. As a result, the bearing members 66 and 67 are locked to the lower frame 28 in a state where rotation is restricted. Further, when each of the bearing members 66 and 67 is rotated about 90 degrees around the drum shaft 35, the fixed portion 70 in which the flat side surfaces 74 and 75 are arranged along the guide direction in the bearing member receiving portion 100 also becomes available. Since it rotates about 90 degrees, the fixed portion 70 is arranged so that the flat side surfaces 74 and 75 are orthogonal to the guide direction and the curved side surfaces 76 and 77 are along the guide direction. Then, since the fixing portion 70 is blocked from passing through the bearing member guide portion 99, the fixing portion 70 is fixed at the bearing member receiving portion 100. Thereby, each bearing member 66, 67 is supported by the lower frame 28. As a result, the upper frame 27 and the lower frame 28 are fixed in a combined state.

When the upper frame 27 and the lower frame 28 are assembled in this way, the bearing members 66 and 67 supported by the upper frame 27 are received and supported by the bearing member receiving portion 100 formed in the lower frame 28. As a result, the upper frame 27 and the lower frame 28 are connected, and the relative positions of the upper frame 27 and the lower frame 28 are positioned via the bearing members 66 and 67, respectively. In other words, the relative positions of the upper frame 27 and the lower frame 28 are positioned with reference to the drum shaft 35 of the photosensitive drum 29 supported by the bearing members 66 and 67. A photosensitive drum 29, a scorotron type charger 30 and a cleaning brush 33 are supported on the upper frame 27, and the relative positions of the photosensitive drum 29, the scorotron type charger 30 and the cleaning brush 33 are set on the photosensitive drum 29. It is positioned with reference to the bearing members 66 and 67 that receive the drum shaft 35, regardless of the assembly of the lower frame 28. Further, the lower frame 28 supports the developing cartridge 31 and the transfer roller 32, and when the upper frame 27 is assembled to the lower frame 28, the positions of the developing cartridge 31 and the transfer roller 32 relative to the upper frame 27. Is positioned with reference to the bearing members 66 and 67 that receive the drum shaft 35 of the photosensitive drum 29.

As a result, all the members arranged around the photosensitive drum 29 as the means of action acting on the photosensitive drum 29, that is, the scorotron type charger 30, the developing cartridge 31, the transfer roller 32, and the cleaning brush 33 are exposed to light. The relative position with respect to the drum 29 is positioned with reference to the drum shaft 35 supported by the bearing members 66 and 67.

Therefore, even if the upper frame 27 and the lower frame 28 have manufacturing errors (tolerances), respectively, the relative positions of the upper frame 27 and the lower frame 28 should be accurately positioned via the bearing members 66 and 67. As a result, the relative positions of the scorotron type charger 30, the developing cartridge 31, the transfer roller 32, and the cleaning brush 33 with respect to the photosensitive drum 29 can be accurately positioned.

Therefore, the photosensitive drum 29 is accurately charged by the scorotron type charger 30, developed accurately by the developing cartridge 31, transferred to the paper 3 accurately by the transfer roller 32, and more accurately by the cleaning brush 33. Since it can be cleaned, the laser printer 1 provided with the process cartridge 20 can form a high quality image on the paper 3.

Further, in this process cartridge 20, when the upper frame 27 and the lower frame 28 are assembled, the fixing portions 70 of the bearing members 66 and 67 are guided to the bearing member guide portion 99 provided on the lower frame 28. , The upper frame 27 and the lower frame 28 can be easily assembled in a state where their relative positions are accurately positioned.

Further, in this process cartridge 20, the upper frame 27 and the lower frame 28 are assembled, and after the fixing portion 70 of each bearing member 66,67 is received by the bearing member receiving portion 100, the bearing member 66,67 If the fixed portion 70 is rotated so as to be orthogonal to the guide direction of the bearing member guide portion 99, it is possible to prevent the fixed portion 70 from being separated from the bearing member receiving portion 100 via the bearing member guide portion 99. .. As a result, the upper frame 27 and the lower frame 28 can be easily and surely prevented from being separated, and the upper frame 27 and the lower frame 28 can be easily fixed.

After that, if the fixed portion 70 of each of the bearing members 66 and 67 is further rotated by 90 degrees so as to follow the guiding direction of the bearing member guide portion 99, the fixed portion 70 is guided from the bearing member receiving portion 100 to the bearing member. Since it can be separated via the portion 99, the fixing between the upper frame 27 and the lower frame 28 can be easily released. That is, in this process cartridge 20, if the bearing members 66 and 67 are rotated about 90 degrees around the drum shaft 35, the upper frame 27 is fixed to the lower frame 28 and the upper frame is fixed. It can be moved alternately to the fixing release position where the fixing to the lower frame 28 of 27 is released. As a result, the upper frame 27 and the lower frame 28 can be easily fixed to each other or released from the fixing, and workability at the time of assembly or separation can be improved.

Further, in this way, if the upper frame 27 and the lower frame 28 are fixed or released by the rotation of the bearing members 66,67, the bearing members 66,67 connect the upper frame 27 and the lower frame 28 to each other. Compared with a configuration in which a fixing means for fixing is separately provided, the number of parts constituting the process cartridge 20 can be reduced and the configuration can be simplified. As a result, the cost of the process cartridge 20 can be reduced.

Further, in a state where the fixing portion 70 of each bearing member 66, 67 is orthogonal to the guide direction of the bearing member guide portion 99, the locking projection 72 of each bearing member 66, 67 is the locking recess 102 of the lower frame 28. Since it is locked to, it is possible to prevent inadvertent rotation of each bearing member 66, 67 with respect to the lower frame 28. Therefore, it is possible to prevent the upper frame 27 and the lower frame 28 from being inadvertently separated.

Moreover, when the locking projection 72 is engaged with and disengaged from the locking recess 102, the bearing members 66 and 67 can be rotated while bending the flange portion 69, so that the locking projection 72 can be rotated with respect to the locking recess 102. Can be easily engaged and disengaged.

In the above embodiment, the first bearing portion and the second bearing portion of the present invention are the same bearing members 66,67, but the first bearing portion and the second bearing portion may be provided separately. ..

In that case, for example, as schematically shown in FIG. 12, a first bearing that supports the drum shaft 35 in the left support hole 60 of the left wall 54 of the upper frame 27 and the right support hole 63 of the right wall 55, respectively. Members 203 and 204 are provided, and instead of forming the bearing member guide portion 99 and the bearing member receiving portion 100 on the pair of side walls 92 of the lower frame 28, shaft insertion holes 205 and 206 for inserting the drum shaft 35 are formed. Second bearing members 207 and 208 may be provided in the shaft insertion holes 205 and 206, respectively.

In this case, for example, the upper frame 27 and the lower frame 28 are arranged so that the left side support hole 60 and the right side support hole 63 of the upper frame 27 and the shaft insertion holes 205 and 206 of the lower frame 28 face each other in the axial direction. In the arranged state, the drum shaft 35 is inserted into the first bearing member 203,204 and the second bearing member 207,208, and is supported by the upper frame 27 and the lower frame 28 via the first bearing member 203,204 and the second bearing member 207,208. Just do it.

In this way, even if the upper frame 27 and the lower frame 28 are provided separately, the scorotron type charger 30, the developing cartridge 31, the transfer roller 32, and the cleaning brush 33 are based on the drum shaft 35 with respect to the photosensitive drum 29. As a result, their relative positions can be positioned with high accuracy.

<figref num="1">It is a main part side sectional view which shows one Embodiment of the laser printer as the image forming apparatus of this invention, and shows the state which the front cover is closed.</figref><figref num="2">It is sectional drawing of the main part side of the laser printer shown in FIG. 1, and shows the state in which the front cover is opened.</figref><figref num="3">It is a top view of the process cartridge shown in FIG.</figref><figref num="4">It is a side view of the process cartridge shown in FIG.</figref><figref num="5">It is sectional drawing in the cutting line AA shown in FIG.</figref><figref num="6">It is sectional drawing in the cutting line BB shown in FIG.</figref><figref num="7">It is a left side view of the bearing member shown in FIG.</figref><figref num="8">It is a front view of the bearing member shown in FIG.</figref><figref num="9">It is a right side view of the bearing member shown in FIG.</figref><figref num="10">It is a side view which shows the state which the upper frame and the lower frame shown in FIG. 4 are separated.</figref><figref num="11">It is a figure for demonstrating the fixing of the upper frame and the lower frame by the bearing member shown in FIG.</figref><figref num="12">It is sectional drawing which shows roughly the structure of another embodiment (a mode in which a 1st bearing part and a 2nd bearing part are provided separately) of another embodiment of a laser printer.</figref>

Code description

1 Laser printer 3 Paper 20 Process cartridge 27 Upper frame 28 Lower frame 29 Photosensitive drum 30 Scorotron type charger 32 Transfer roller 35 Drum shaft 66 Bearing member 67 Bearing member 68 Shaft insertion part 69 Flange part 70 Fixing part 72 Locking protrusion 73 Length Hole 99 Bearing member guide 100 Bearing member receiving part 102 Locking recess 203 1st bearing member 204 1st bearing member 207 2nd bearing member 208 2nd bearing member