CN101436034A - Process cartridge for image-forming device - Google Patents

Abstract

The present invention provides a process cartridge used in an image forming apparatus and an image forming apparatus, wherein the process cartridge used in the image forming apparatus includes: a drum casing accommodating a photosensitive drum carrying a developer image, the photosensitive drum being formed as cylindrical, and is rotatably supported by the drum casing around its rotational axis; and a developing body casing detachably mounted on the drum casing; wherein either one of the drum casing and the developing body casing has ribs, the The rib is formed in a plate shape and extends in a direction perpendicular to the rotation axis of the photosensitive drum; and wherein the other of the drum casing and the developing body casing has a positioning unit engaged with the rib in a A positioning unit for positioning the drum casing and the developing body casing relative to each other in a direction.

Description

Process cartridge for image forming apparatus

This application is a divisional application of the following application

Filing date of original application: April 27, 2006

Application number of the original application: 200610079940.X

Title of invention of the original application: Process cartridge for image forming apparatus

Cross-references to related applications

This application claims priority to Japanese Patent Application No. 2005-130199 filed on April 27, 2005 and Japanese Patent Application No. 2005-131350 filed on April 28, 2005. The entire contents of each of the priority applications are hereby incorporated by reference.

technical field

The present invention relates to an image forming apparatus, such as a laser printer, which forms an image by developing an electrostatic latent image with a developer, and to a cartridge detachably mounted in the image forming apparatus.

Background technique

One type of process cartridge used in the image forming apparatus disclosed in US Pat. No. 6,330,410 includes a drum cartridge accommodating a photosensitive drum and a developer cartridge (toner cartridge) detachably mounted on the drum cartridge. The developer cartridge is equipped with a developing roller for carrying toner on its surface to develop the electrostatic latent image formed on the photosensitive drum.

Contents of the invention

In this type of image forming apparatus and process cartridge, when the developer cartridge is mounted on the drum cartridge, the drum cartridge and the developer cartridge must be precisely positioned with each other so that there is nothing at a predetermined position on the recording medium (paper). An image is erroneously formed.

It is conceivable that by installing the developer cartridge in the developer cartridge accommodating portion provided in the drum cartridge and bringing the outer surface of the developer cartridge in the width direction into contact with both inner side surfaces of the developer cartridge accommodating portion, mutual Position the drum cartridge and developer cartridge. However, this conceived positioning method may be affected by cumulative errors, including errors in the outer dimensions of the drum cartridge (ie, errors in the dimensions of the two opposing inner surfaces of the developer cartridge accommodating portion), errors in the outer dimensions of the developer cartridge, , and the installation position error of the photosensitive drum and developing roller in their respective cartridges. This accumulated error seriously degrades the accuracy of the relative positions of the photosensitive drum and the developing roller.

The dimensional tolerance of the developer cartridge accommodating portion and the developer cartridge is relatively large because the dimension between the inner surfaces of the accommodating portion and the dimension between the outer surfaces of the developer cartridge are larger than the maximum size of paper usable in the image forming apparatus . Therefore, if the gap between the inner surface of the developer cartridge accommodating portion and the outer surface of the developer cartridge is relatively large, the developer cartridge has a large room for play, that is, a large play in the paper width direction in the drum case. Gap. However, reducing the gap to reduce the amount of play reduces the smoothness of mounting and removing the developer cartridge to and from the developer cartridge accommodating portion.

Another type of process cartridge disclosed in Unexamined US Patent Application Publication No. 2005/0019056 is equipped with a paper dust removing portion for removing paper dust deposited on the surface of the photosensitive drum. The process cartridge includes a holder provided on a process cartridge frame. A paper dust removing portion is attached to the holder. The paper dust removing part includes a brush-shaped member supported on the board.

The brush-shaped member contacts the surface of the photosensitive drum in the process cartridge. The plate supporting the brush member is attached to the holder on the frame. The rear surface of the plate on the side opposite to the surface supporting the brush member is blocked by the frame. In a high temperature environment, heat accumulated in the frame may raise the temperature of the plate, which softens the toner deposited on the brush member and promotes filming on the photosensitive drum.

Further, when the process cartridge having the above structure is installed in the image forming apparatus, the paper dust removing portion is provided between the photosensitive drum and the fixing unit. Then, the plate of the paper dust removing portion tends to rise in temperature by the hot air from the fixing unit.

In view of the foregoing problems, an object of the present invention is to provide a process cartridge in which the process cartridge can be smoothly installed in a drum cartridge with reduced positional error.

According to one aspect, the present invention provides a process cartridge. The process cartridge is used in an image forming apparatus. The process cartridge includes a drum casing and a developing body casing. The drum housing houses a photosensitive drum carrying a developer image. The photosensitive drum is formed in a cylindrical shape, and is rotatably supported by the drum casing about its rotational axis. The developing body casing is detachably mounted on the drum casing. Either one of the drum casing and the developing body casing has a rib formed in a plate shape extending in a direction perpendicular to the rotation axis of the photosensitive drum. The other of the drum casing and the developing body casing has a positioning unit engaged with the rib to position the drum casing and the developing body casing with each other in a direction parallel to the rotation axis of the photosensitive drum.

According to another aspect, the present invention provides an image forming apparatus. The image forming apparatus includes a main frame, a process cartridge, and a developing body casing. The process cartridge is detachably installed in the main frame. The process cartridge includes a drum casing housing a photosensitive drum. The photosensitive drum, on which an electrostatic latent image is formed, bears an electrostatic latent image, is formed in a cylindrical shape and is rotatably supported by a drum casing about its rotational axis, and on which the electrostatic latent image is formed. The developing body casing is detachably mounted on the drum casing and rotatably supports a developing roller parallel to and facing the photosensitive drum. The developing roller is cylindrical and configured to carry a developer on its peripheral surface to develop the electrostatic latent image into a developer image. The main frame and drum casing include a positioning mechanism that positions the drum casing relative to the main frame in a direction parallel to the rotation axis of the photosensitive drum. Either one of the drum casing and the developing body casing has a rib configured to position the drum casing and the developing body casing with each other in a direction parallel to the rotation axis of the photosensitive drum. The other of the drum casing and the developing body casing has a positioning unit configured to engage with the rib to position the drum casing and the developing body casing with each other in a direction parallel to the rotation axis of the photosensitive drum.

Description of drawings

Various illustrative aspects of the invention will be described in detail with reference to the following figures.

1 is a side sectional view of a laser printer according to an aspect of the present invention;

Fig. 2 is a side sectional view of the drum cartridge used in the laser printer of Fig. 1;

Fig. 3 is a side sectional view of a process cartridge used in the laser printer of Fig. 1;

Figure 4 is a perspective view viewed from the top of the rear side of the drum box;

Figure 5 is a perspective view viewed from above the front side of the drum cartridge lower shell;

Figure 6 is a perspective view from below the front side of the drum cartridge upper shell (before attachment of the cleaning member);

Figure 7 is a perspective view from below the front side of the drum cartridge upper shell (after attachment of the cleaning member);

Figures 8A and 8B, Figures 9A and 9B, and Figures 10A and 10B illustrate the process of assembling the cleaning member to the upper housing, wherein: Figure 8A is the main part of the upper housing and the cleaning member before the cleaning member is installed on the upper housing Figure 8B is a cross-sectional view of Figure 8A; Figure 9A is a perspective view of the main part of the upper housing and the cleaning member when the cleaning member is being installed on the upper housing; Figure 9B is a cross-sectional view of Figure 9A; Figure 10A It is a perspective view of the main part of the upper housing and the cleaning member after the cleaning member is completely installed on the upper housing; FIG. 10B is a cross-sectional view of FIG. 10A;

11A is a side sectional view of the drum cartridge illustrating the positional relationship between the cleaning member and the opening and illustrating the positional relationship between the positioning recess and the developing roller;

11B is a side sectional view illustrating the positional relationship between the inner rear wall and the cleaning member and illustrating how the photosensitive drum is positioned relative to the developing roller when the developer cartridge is installed in the drum cartridge;

Figure 12 illustrates the engagement unit provided on the drum cartridge lower shell;

Fig. 13 is a perspective view showing a developer cartridge viewed from below;

14 is a partially cutaway perspective view illustrating a structure for positioning the drum cartridge and the developer cartridge relative to each other in the paper width direction (left-right direction) when the developer cartridge is installed in the drum cartridge; and

FIG. 15 is a horizontal sectional view of a process cartridge mounted in a main frame of the laser printer of FIG. 1. FIG.

Detailed ways

A process cartridge for an image forming apparatus according to aspects of the present invention will be described below with reference to the drawings, in which like parts and elements are denoted by like reference numerals to avoid repetitive description.

1. The overall structure of the laser printer

FIG. 1 is a side sectional view of a laser printer 1 according to an aspect of the present invention. FIG. 2 is a side sectional view of the drum cartridge 27 employed in the laser printer 1 shown in FIG. 1 .

As shown in FIG. 1 , a laser printer 1 includes a main casing 2 and a feeding unit 4 inside the main casing 2 for feeding paper 3 , and an image forming unit 5 that forms an image on the paper 3 fed from the feeding unit 4 .

(1) Main housing

The main case 2 is integrally formed of a substantially rectangular parallelepiped synthetic resin plate. The main case 2 serves to cover a main frame 200 ( FIG. 15 ) that supports various components housed in the main case 2 . The main case 2 includes a top surface 181 , a paper discharge tray 62 formed on part of the top surface 181 , and a discharge opening 182 formed on the upper portion of the main case 2 above the lower portion of the paper discharge tray 62 . The discharge tray 62 slopes downward from the front side of the top surface 181 to the rear side of the top surface 181 , forming a depression in the top surface 181 . The discharge tray 62 is used to receive paper discharged through the discharge port 182 .

The laser printer 1 also includes an access opening 6 formed in one side wall of the main casing 2 for inserting and removing a process cartridge 20 to be described hereinafter, and a front cover 7 capable of opening and closing the access opening 6. Opening 6. The front cover 7 is rotatably supported by a cover shaft 8 inserted through the bottom edge of the front cover 7 . Thus, when the front cover 7 is rotated and closed around the cover shaft 8, the front cover 7 covers the access opening 6, as shown in FIG. 1 . When the front cover 7 is rotated open about the cover shaft 8 , the access opening 6 is exposed so that the process cartridge 20 can be installed into or removed from the main casing 2 through the access opening 6 .

The terms "upper", "lower", "left", "right", "front", "rear" etc. will be used throughout the specification, and it is assumed that the laser printer 1 is to be used and the process cartridge 20 is installed therein. Orientation settings. In use, the setup of the laser printer 1 and the installation of the process cartridge in the laser printer 1 are shown in FIG. 1 . Therefore, the side of the laser printer 1 on which the front cover 7 is mounted and the corresponding side of the process cartridge 20 when the process cartridge 20 is mounted in the main casing 2 are referred to as "front side", while the opposite side is referred to as "rear side". ". The left-right direction is also referred to as "paper width direction". The vertical direction is called "height direction".

The main housing 2 is also equipped with an exhaust fan 119 that exhausts air from the main housing 2 and a duct 120 that guides the air to the exhaust fan 119 .

An exhaust fan 119 is provided above the fixing unit 21 described below. The duct 120 has a downstream end 120 a and an upstream end 120 b in the direction in which air flows through the duct 120 . The downstream end portion 120a leads to the exhaust fan 119, and the upstream end portion 120b extends between the fixing unit 21 and the process cartridge 20, more specifically, from an opening 115 which will be described below formed in the process cartridge 20 to the fixing unit 21 and the process cartridge 20. The area between the cartridges.

(2) Feed unit

The feed unit 4 includes a paper tray 9 , a separation roller 10 , a separation pad 11 and a feed roller 12 . The paper tray 9 can be inserted into or removed from the lower part of the main casing 2 in the front-rear direction, the separation roller 10 and the separation pad 11 are arranged above the front end of the paper tray 9, and the feed roller 12 is arranged in the conveying direction of the separation pad 11 relative to the paper 3 The rear side of the upstream separation roller 10 (hereinafter referred to as the paper conveyance direction). The feeding unit 4 also includes a paper dust removal roller 13 and a pinch roller 14, the paper dust removal roller 13 is arranged on the upper front of the separation roller 10 and the downstream of the separation roller 10 in the paper conveying direction, the pinch roller 14 and the paper dust removal roller 13 relative settings.

The paper conveying path of the paper 3 is formed in a substantially U-shape in the vicinity of the paper dust removing roller 13 in the feeding end reverse direction, toward the rear side of the laser printer 1 . The feeding unit 4 also includes a pair of registration rollers 15 disposed below the process cartridge 20 further downstream of the U-shaped portion of the paper conveying path with respect to the paper conveying direction. The upstream guide 186 is provided around the pinch roller 14 . The upstream guide 186 guides the paper 3 from the pinch roller 14 to reverse the paper 3 to the rearward direction. The bottom guide 187 is provided between the downstream end of the upstream guide 186 and the registration roller 15 . The bottom guide 187 supports the paper from below. The bottom guide 187 guides the sheet from the pinch roller 14 toward the process cartridge 20 .

A paper platen 16 is provided in the paper tray 9 to support the paper 3 in a stacked state. The platen 16 is pivotally supported at its rear end so that the front end pivots downward to a rest position where the platen 16 rests on the bottom plate of the paper tray 9 and is pivotable upward to a feed position, The platen 16 is inclined upward from the rear end to the front end at the feeding position.

A lever 17 is provided at the front of the paper tray 9 for lifting the front end of the paper platen 16 upward. The rear end of the rod 17 is pivotally supported on the rod shaft 18 at the position below the front end of the platen 16, so that the front end of the rod 17 can be placed horizontally along the bottom plate of the paper tray 9 and the horizontal position of the rod 17. The front end lifts up and pivots between the inclined positions of the platen 16 . When a driving force is input to the lever shaft 18, the lever 17 rotates around the lever axis 18, and the front end of the lever 17 lifts the front end of the platen 16, switching the platen 16 to the feeding position.

When the platen 16 is in the feeding position, the topmost sheet of the sheets 3 stacked on the platen 16 is pressed against the feed roller 12 . The rotating feed roller 12 starts feeding the sheet 3 to the separation position between the separation roller 10 and the separation pad 11 .

When the paper tray 9 is removed from the main housing 2, the paper platen 16 stays to the rest position. When the platen 16 is at the parking position, the paper 3 can be stacked on the platen 16 .

The rotating separation roller 10 separates and feeds the paper 3 one at a time while the feed roller 12 conveys the paper 3 toward the separation position and the paper is interposed between the separation roller 10 and the separation pad 11 . Each sheet 3 fed by the separation roller 10 passes between the dust removal roller 13 and the pinch roller 14 . After the paper dust removal roller 13 removes paper dust from the paper 3 , the paper is conveyed along the U-shaped paper conveyance path at the feed end, thus reversing the direction and conveyed toward the registration roller 15 .

After registering the paper 3, the registration roller 15 conveys the paper 3 to a transfer position between the photosensitive drum 28 and the transfer roller 31 described below, where the toner image formed on the photosensitive drum 28 is transferred. Transfer to paper 3.

(3) Image forming unit

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

(a) Scanning unit

The scanning unit 19 is disposed on the top of the main housing 2 and includes a laser source (not shown), a polygon mirror 22 capable of being driven to rotate, an fθ lens 23 , a mirror 24 , a lens 25 and a mirror 26 . A laser source emits a laser beam based on image data. 1, the laser beam is deflected by the polygon mirror 22, passes through the fθ lens 23, is reflected by the reflection mirror 24, passes through the lens 25, and is reflected downward by the reflection mirror 26 to irradiate the process cartridge 20. on the surface of the photosensitive drum 28 in.

(b) Disposal cartridge

As shown in FIG. 1 , the process cartridge 20 is disposed below the scanning unit 19 in the main casing 2 and can be installed into or removed from the main casing 2 through the access opening 6 .

As shown in FIG. 3 , the process cartridge 20 includes a drum cartridge 27 and a developer cartridge 30 detachably mounted on the drum cartridge 27 .

As shown in FIG. 2, the drum cartridge 27 includes a drum casing 76 which will be described in more detail below, and a photosensitive drum 28 inside the drum casing 76, a scorotron charger 29, a transfer roller 31 and a cleaning member 32. .

The photosensitive drum 28 includes a cylindrical main drum body 33 and a metal drum shaft 34, the main drum body 33 is cylindrical and has a positively charged photosensitive layer formed on the outer peripheral surface 33a of the main drum body 33 by polymer Formed of carbonate or the like, the metal drum shaft 34 extends through the center of the main drum body 33 in the axial direction of the main drum body 33 . The metal drum shaft 34 is supported in the drum shell 76 and the main drum body 33 is rotatably supported relative to the metal drum shaft 34 . With such a structure, the photosensitive drum 28 is disposed within the drum casing 76 and is rotatable about the metal drum shaft 34 . Further, the photosensitive drum 28 is driven to rotate by a driving force input from a motor (not shown). When the process cartridge 20 is mounted on the main casing 2, the axial direction of the drum shaft 34 is parallel to the paper width direction.

The charger 29 is supported on the drum casing 76 at the upper rear of the diagonal of the photosensitive drum 28 . The charger 29 is opposed to the photosensitive drum 28 but is spaced a predetermined distance from the photosensitive drum 28 so as not to contact the photosensitive drum 28 . The charger 29 includes a discharge wire 74 disposed opposite to the photosensitive drum 28 but at a predetermined distance therefrom, and a grid 75 disposed between the discharge wire 74 and the photosensitive drum 28 for controlling the discharge wire reaching the photosensitive drum 28. 35 corona discharge capacity. The charger 29 can charge the surface of the photosensitive drum 28 with uniform positive polarity by applying a high voltage to the discharge line 74 to generate a corona discharge from the discharge line 74 while applying a bias voltage to the grid 75 .

The transfer roller 31 is disposed below the photosensitive drum 28 in the drum casing 76 and contacts the photosensitive drum 28 from the bottom of the photosensitive drum 28 in the vertical direction so as to form a nip portion with the photosensitive drum 28 . The transfer roller 31 is composed of a metal roller shaft 56 covered with a roller body 57 made of a conductive rubber material. The roller shaft 56 is rotatably supported in the drum shell 76 . The transfer roller 31 is driven to rotate by a driving force input from a motor (not shown). In addition, in the transfer operation, a transfer bias is applied to the transfer roller 31 .

A paper inlet 133 is formed in the drum housing 76 upstream of the transfer roller 31 in the paper conveyance direction as a channel for guiding the paper to a transfer position between the photosensitive drum 28 and the transfer roller 31 in the drum housing 76. Open your mouth. A paper outlet 134 is also formed in the drum housing 76 downstream of the transfer roller 31 in the paper conveying direction as an opening through which the paper is discharged from the drum housing 76 .

The cleaning member 32 is installed in the drum casing 76 at a position facing the photosensitive drum 28 from the rear side thereof. As will be described in more detail below, the cleaning member 32 includes a cleaning brush 65 that captures paper dust deposited on the photosensitive drum 28 and a support plate 66 that supports the side of the cleaning brush 65 on the side opposite to the photosensitive drum 28. rear side.

The cleaning brush 65 is made of non-woven fabric, the non-woven fabric is implanted with a plurality of conductive fiber bristles, and the cleaning brush 65 is fixed on the support plate 66 by double-sided adhesive tape. The cleaning brush 65 is provided to face and contact the photosensitive drum 28 . It is also possible to simply attach a nonwoven fabric without fiber bristles to the support plate 66 and place the support plate 66 in contact with the photosensitive drum 28, provided the nonwoven fabric is capable of capturing paper dust.

When the support plate 66 is supported on the drum shell 76 , an electrode plate 111 (see FIG. 8A ), which will be described later, pushes the support plate 66 in a direction toward the photosensitive drum 28 from the side opposite to the cleaning brush 65 . The electrode plate 111 also applies an electrical bias to the support plate 66 during cleaning operations.

As will be described in more detail below, a collection unit 118 is disposed on the drum casing 76 below the cleaning member 32 for collecting paper dust removed by the cleaning member 32 .

As shown in FIG. 3 , the developer cartridge 30 is detachably mounted on the drum casing 76 . Thus, when the process cartridge 20 has been mounted in the main casing 2, the developer cartridge 30 can be detached from the main casing 2 by first opening the front cover 7 and then removing the developer cartridge 30 from the drum cartridge 27 through the access opening 6, And another developer cartridge 30 is mounted on the drum cartridge 27.

As shown in FIG. 3 , the developer cartridge 30 includes a developing body casing 36 , and a supply roller 37 , a developing roller 38 and a thickness regulating blade 39 in the developing body casing 36 .

As shown in FIG. 13 , the developing body casing 36 is formed in a box shape opened on the rear side. A partition wall 40 is provided in the developing body casing 36 for partitioning the inside of the developing body casing 36 into a toner containing chamber 41 and a developing chamber 42 .

(c) Developer cartridge

The developing body housing 36 includes a bottom wall 141 , two side walls 143 (a left side wall 143 a and a right side wall 143 b ) ( FIG. 13 ), and a top wall 142 . The side walls 143 of the developing body housing 36 are connected to both lateral edges of the bottom wall 141 . The bottom wall 141 and the side wall 143 are integrally formed of synthetic resin by injection molding.

A space surrounded by the bottom wall 141 and the pair of side walls 143 is open at top edges and rear surface sides of the bottom wall 141 and the side walls 143 . The top wall 142 covers the opening formed by the top edges of the side walls 143 .

A partition wall 40 is provided at an intermediate position in the front-rear direction in the developing body casing 36 for partitioning the inside of the developing body casing 36 in the front-rear direction. The opening 43 passes through the middle region of the partition wall 40 . The protruding wall 144 protrudes upward from the bottom wall 141 . The protruding wall 144 is disposed between the agitator 45 and the supply roller 37 .

The toner containing chamber 41 occupies a space on the front side of the casing 36 partitioned by the partition wall 40 . The toner containing chamber 41 is filled with non-magnetic one-component toner having positive charge characteristics. The toner used in this example is a polymerized toner obtained by copolymerizing polymerized monomers using a known polymerization method such as suspension polymerization. For example, the polymerized monomer may be a styrene monomer such as styrene or an acrylic monomer such as acrylic acid, alkyl (C1 to C4) acrylate, or alkyl (C1 to C4) metaacrylate. In order to have very good flowability and thus to form high quality images, the toner is polymerized to form substantially spherical particles.

This type of toner is mixed with a colorant such as carbon black, paraffin and additives such as silica in order to improve fluidity. The average diameter of the toner particles is about 6 to 10 microns.

A toner supply port for filling the toner accommodating chamber 41 with toner is formed in both side walls 143 of the developing body housing 36 defining the toner accommodating chamber 41 . The toner supply port is sealed by a cap 35 .

Toner detection windows 44 are provided in both side walls 143 of the housing 36 defining the toner containing chamber 41 for detecting the amount of toner remaining in the toner containing chamber. The toner detection windows 44 are formed in the side wall 143 in the vicinity of the partition wall 40, and face each other across the width direction of the toner containing chamber 41 (the direction orthogonal to the front-rear direction and the vertical direction). The toner detection window 44 is formed by embedding a transparent disk-shaped plate in each side wall 143 .

A stirrer 45 is provided in the toner containing chamber 41 for stirring the toner contained therein. The stirrer 45 includes a rotating shaft 46 and a stirring member 47 .

The shaft 46 is rotatably supported in the side wall 143 substantially at the center of the toner containing chamber 41 . The stirring member 47 is provided on the rotating shaft 46 . A motor (not shown) generates a driving force input to the rotary shaft 46 to rotate the rotary shaft 46 . As a result, the agitating member 47 moves along a circular path around the rotation shaft 46 passing through the toner-accommodating chamber 41 and agitates the toner contained in the toner-accommodating chamber 41 . When the stirring member 47 stirs the toner, some of the toner is discharged toward the supply roller 37 in the front-rear direction through the opening 43 formed in the partition plate 40 .

The agitator 45 also includes wipers 48 attached to both axial ends of the rotating shaft 46 . When the rotating shaft 46 rotates, the wiper 48 moves in a circular direction around the rotating shaft 46 passing through the toner containing chamber 41 , and its purpose is to wipe the toner detection window 44 provided on the side wall 143 . Therefore, the wiper 48 is used to wipe the toner detection window 44 clean.

The developing chamber 42 occupies the inner space on the rear side of the casing 36 partitioned by the partition wall 40 and the protruding wall 144 . The developing chamber 42 accommodates the supply roller 37 , the developing roller 38 and the thickness regulating blade 39 .

The supply roller 37 is disposed behind the opening 43 in the developing chamber 42 and includes a metal roller shaft 50 covered with a sponge roller body 51 made of conductive foam material. The roller shaft 50 is rotatably supported in both side walls 143 of the casing 36 within the developing chamber 42 . The supply roller 37 is driven to rotate by a driving force input from a motor (not shown) to the roller shaft 50 .

During image formation, the supply roller 37 is driven to rotate counterclockwise in FIG. 1 for supplying charged toner to the peripheral surface of the developing roller 38 .

The developing roller 38 is disposed behind the supply roller 37 and contacts the supply roller 37 with a certain pressure. The developing roller 38 includes a metal roller shaft 52 and a rubber roller body 53 formed of a conductive rubber material and covering the roller shaft 52 . The rubber roller body 53 has an outer peripheral surface 53a ( FIG. 3 ). The roller shaft 52 is rotatably supported by a pair of side walls 53 inside the developing chamber 42 . More specifically, the rubber roller body 53 is formed of conductive urethane rubber or silicone rubber containing fine carbon particles, and its surface is covered with fluorine-containing urethane rubber or silicone rubber. The developing roller 38 is driven to rotate by a driving force input from a motor (not shown) to the roller shaft 52 . In addition, a developing bias is applied to the developing roller 38 during the developing operation.

When the developer cartridge 30 is mounted on the drum casing 76, the developing roller 38 is parallel to the photosensitive drum 28, and the outer peripheral surface 53a of the developing roller 38 exposed from the developing body casing 36 is opposed to the photosensitive drum 28 and passes through the The thin layer of toner carried on the peripheral surface 53 a contacts the peripheral surface 33 a of the photosensitive drum 28 .

The thickness regulating blade 39 includes a main blade member 54 formed of a metal leaf spring and a pressing portion 55 provided at a distal end of the main blade member 54 . The pressing portion 55 has a semicircular cross section and is formed of insulating silicone rubber. The base end of the main blade member 54 is supported on the developing body housing 36 above the developing roller 38 , and the pressing portion 55 contacts the developing roller 38 with a certain pressure by the elastic force of the main blade member 54 .

By rotating the supply roller 37 , the toner discharged through the opening 43 is supplied onto the developing roller 38 . At this time, the toner is positively charged by friction between the supply roller 37 and the developing roller 38 . When the developing roller 38 rotates, the toner supplied onto the surface of the developing roller 38 passes between the rubber roller body 53 of the developing roller 38 and the pressing portion 55 of the thickness regulating blade 39, and forms a toner on the surface of the developing roller 38. Toner layer. The thickness regulating blade 39 regulates the thickness and charging amount of the toner held on the developing roller 38 .

As the photosensitive drum 28 rotates, the charger 29 charges the surface of the photosensitive drum 28 with uniform positive polarity. Subsequently, the laser beam emitted from the scanning unit 19 scans the surface of the photosensitive drum 28 at high speed, forming an electrostatic latent image corresponding to the image to be formed on the paper 3 .

Next, the positively charged toner carried on the surface of the developing roller 38 comes into contact with the photosensitive drum 28 as the developing roller 38 rotates, and is provided on the positively charged photosensitive drum 28 surface to be exposed to the laser beam so that it has a lower area of potential. Thus, the latent image on the photosensitive drum 28 is converted into a visible image according to the process of reverse development, so that the toner image is carried on the surface of the photosensitive drum 28 .

Note that, as shown in FIG. 15, the effective latent image forming area 236 is defined as an area on the peripheral surface 33a on which a photosensitive layer is properly formed and therefore an electrostatic latent image can be properly formed. The effective latent image forming area 236 has a pair of effective area boundaries 235 (left end effective area boundary 235 a and right end effective area boundary 235 b ) on opposite ends thereof in the paper width direction. The effective area boundaries 235 are located on two opposite end areas of the photosensitive drum 28 in the paper width direction.

The length of the outer peripheral surface 53 a of the rubber roller body 53 in the paper width direction is sufficiently larger than the length of the effective latent image forming region 236 of the photosensitive drum 28 in the paper width direction. The effective image forming area is defined on the outer peripheral surface 53a of the rubber roller body 53 as an area where the thickness regulating blade 39 effectively supplies toner to have a prescribed thickness and a prescribed charge amount. The length of the effective image forming area in the paper width direction is slightly larger than the length of the effective latent image forming area 236 in the paper width direction (in this example, several millimeters longer). Note, however, that the length of the effective image forming area in the paper width direction may be equal to the length of the effective latent image forming area 236 in the paper width direction.

Subsequently, when the registration roller 15 conveys the sheet 3 into the drum casing 76 and passes it through the transfer position between the photosensitive drum 28 and the transfer roller 31, by the transfer bias applied to the transfer roller 31, The toner carried on the surface of the photosensitive drum 28 is transferred onto the paper 3 . Next, the paper 3 onto which the toner is transferred is conveyed to the fixing unit 21 .

Toner remaining on the surface of the photosensitive drum 28 after transfer is recovered by the developing roller 38 . Further, the cleaning brush 65 of the cleaning member 32 physically scrapes off paper dust deposited on the surface of the photosensitive drum 28 from the paper 3 . Further, an electrode plate 111 ( FIG. 8A ) applies a bias to the support plate 66 for electrically attracting paper dust from the surface of the photosensitive drum 28 . The paper dust removed by the cleaning member 32 is collected in the collecting unit 118 provided below the cleaning member 32 .

As shown in FIG. 1 , the intermediate guide 188 is provided between the paper outlet 134 of the drum housing 76 and the fixing unit 21 . The middle guide 188 supports the paper 3 from below. The paper 3 is conveyed from the process cartridge 20 to the fixing unit 21 while being guided by the intermediate guide 188 .

(d) Fixing unit

As shown in FIG. 1, when the process cartridge 20 is installed in the main casing 2, the fixing unit 21 is disposed on the rear side of the process cartridge 20, separated from the photosensitive drum 28 of the process cartridge 20 in a substantially horizontal direction. The fixing unit 21 includes a fixing frame 59 and a heating roller 60 and a pressure roller 61 disposed inside the fixing frame 59 .

The heating roller 60 includes a metal tube and a halogen lamp, the surface of the metal tube is covered with fluorine-containing resin, and the halogen lamp is arranged inside the metal tube for heating the metal tube. The heating roller 60 is driven to rotate by a driving force input from a motor (not shown).

The pressure roller 61 is disposed below the heat roller 60 , faces the heat roller 60 and contacts the heat roller 60 with pressure. The pressure roller 61 is composed of a metal roller shaft covering a roller body formed of a rubber material. The pressure roller 61 is driven following the rotation of the heating roller 60 .

In the fixing unit 21 , when the paper 3 passes between the heat roller 60 and the pressure roller 61 , the toner image transferred onto the paper 3 at the transfer position is fixed to the paper 3 by heating. After the toner image is fixed on the paper 3 , the heat roller 60 and the pressure roller 61 continue to convey the paper 3 along the discharge end paper conveyance path toward the discharge tray 62 formed on the top surface of the main casing 2 .

The paper transport path on the discharge end leads from the fixing unit 21 to the discharge tray 62 and is substantially U-shaped for reversing the transport direction of the paper 3 to a direction toward the front of the laser printer 1 . A conveyance roller 63 is provided at a midpoint along the paper conveyance path at the discharge end, and a pair of discharge rollers 64 is provided at a downstream end of the same path.

Therefore, when passing through the fixing unit 21, while being guided by the downstream guide 189, the paper 3 is conveyed along the discharge end paper conveying path, at this time the conveying roller 63 receives the paper 3 and conveys the paper 3 to the discharge roller 64, and then the discharge roller 64 The paper 3 is received and conveyed onto the discharge tray 62 .

The hot air generated from the heating roller 60 of the fixing unit 21 undergoes heat radiation and flows toward the photosensitive drum 28 of the process cartridge 20 . However, since the upstream end 120 b of the duct 120 is positioned between the fixing unit 21 and the process cartridge 20 , the duct 120 guides hot air to the exhaust fan 119 which exhausts the air from the main casing 2 .

2. Drum shell and cleaning member

FIG. 4 is a perspective view seen from the upper rear side of the drum cartridge 27. As shown in FIG. FIG. 5 is a perspective view seen from the upper front side of the lower case 77 of the drum cartridge 27 . FIG. 6 is a perspective view seen from the lower front side of the upper housing 78 of the drum cartridge 27 before the cleaning member 32 is attached. FIG. 7 is a perspective view from the lower front side of the upper housing 78 of the drum cartridge 27 after the cleaning member 32 has been attached. 8A to 10B illustrate the steps of assembling the cleaning member 32 on the upper housing 78 . 11A and 11B illustrate the positional relationship between the cleaning member 32, the opening 115, and the inner rear wall 91 (to be described later).

Next, the drum shell 76 of the drum cartridge 27 and the cleaning member 32 mounted on the drum shell 76 will be described in detail with reference to FIGS. 1 to 11B .

(1) The structure of the drum shell

As shown in FIGS. 2 and 4 , the drum shell 76 includes a lower shell 77 , and an upper shell 78 formed separately from the lower shell and fitted on top of the lower shell 77 .

(a) Lower shell

As shown in FIG. 5, the lower case 77 is integrally equipped with a developer cartridge mounting unit 79 provided on its front side for receiving the developer cartridge 30, and a developer cartridge mounting unit 79 provided on its rear side and positioned to face the upper case 78 vertically. Drum support unit 80 .

As shown in FIGS. 2 and 5, the developer cartridge installation unit 79 is integrally provided with a front bottom wall having a substantially rectangular plate shape for receiving the developer cartridge 30; provided at each lateral end of the front bottom wall 81 and separated The front bottom wall 81 has two front side walls 82 (front left side wall 82 a and front right side wall 82 b ) whose widths are opposed to each other; and a lower front wall 83 provided at the front end of the front bottom wall 81 . The developer cartridge installation unit 79 is formed in a frame shape having a bottom and an open top. As shown in FIG. 4, a handle 84 is formed at the lateral center region of the lower front side wall 83 for holding the drum cartridge 27 when installing or removing the drum cartridge 27. As shown in FIG.

As shown in FIGS. 2 and 5 , the drum supporting unit 80 is integrally equipped with a rear bottom wall 85 having a curved shape at its bottom for receiving the transfer roller 31; it is arranged at both lateral ends of the rear bottom wall 85 and separated by the rear bottom wall. Two rear sidewalls 86 (rear left sidewall 86a and rear right sidewall 86b) with a width of 85 opposite to each other;

The front end of the rear bottom wall 85 is continuously formed with the rear edge of the front bottom wall 81 . The front bottom wall 81 and the rear bottom wall 85 thus integrally form the bottom wall 151 of the lower case 77 . As shown in FIG. 2, the rear bottom wall 85 is shaped to be bent and sunk downward at the center from the front edge to the rear edge so that it is substantially fan-shaped when viewed from the side. Transfer roller receiving portions 88 are formed at both lateral ends of the rear bottom wall 85 for receiving the transfer roller 31 .

As shown in FIGS. 2 and 5 , the paper inlet 133 is formed in the bottom wall 151 at a position where the front bottom wall 81 is connected to the rear bottom wall 85 . The paper inlet 133 is located at the central area of the bottom wall 151 in the paper width direction, and is elongated in the width direction. An engaging unit 152 (to be described later) is provided on the left side of the left edge of the paper inlet 133 .

The two rear side walls 86 are curved to stand vertically from the lateral edges of the rear bottom wall 85 . Through holes 89 are formed in the rear side wall 86 at positions opposed to each other in the width direction for insertion of the drum shaft 34 of the photosensitive drum 28 .

The rear left side wall 86a and the front left side wall 82a together make up the left side wall 156a of the drum shell 76 . The rear right side wall 86b and the front right side wall 82b together make up the right side wall 156b of the drum shell 76 . The left side wall 156a and the right side wall 156b will be collectively referred to as "side walls 156" hereinafter.

The lower rear wall 87 is formed continuously from the rear edge of the rear bottom wall 85 across the entire width between the rear side walls 86 . Viewed from the front, the lower rear wall 87 is an elongated rectangular plate standing vertically and extending in the width direction. As shown in FIG. 2 , the receiving plate 90 is formed continuously with the lower rear wall 87 and extends forward from the bottom edge of the lower rear wall 87 with a slight downward slope. A paper outlet 134 is formed in the central area in the paper width direction in the rear bottom wall 85 and is located at the front lower side of the receiving plate 90 . The paper outlet 134 is elongated in the paper width direction.

The inner rear wall 91 as a heat shield and the positioning wall 92 stand vertically from the receiving plate 90 in front of the lower rear wall 87 and are parallel to each other, but separated by a prescribed distance in the front-rear direction.

The inner rear wall 91 is provided in front of the lower rear wall 87 at a predetermined distance from the lower rear wall 87 . The inner rear wall 91 extends in the width direction and is parallel to the lower rear wall 87 . The positioning wall 92 also extends in the width direction and is parallel to the inner rear wall 91 . The positioning wall 92 is provided in front of the inner rear wall 91 at a predetermined distance from the inner rear wall 91 . The positioning wall 92 functions to position the cleaning member 32 .

A film member 117 ( FIG. 2 ) is provided at the front end of the receiving plate 90 to contact the photosensitive drum 28 . The film member 117 is adhesively fixed to the end surface on the front end of the receiving plate 90 and protrudes upward therefrom. The film member 117 extends in the width direction, and serves as a barrier between the receiving plate 90 and the photosensitive drum 28 . The positioning wall 92, the receiving plate 90 and the membrane member 117 form a collecting unit 118 with an open top having a substantially rectangular appearance in side section.

(b) Upper case

As shown in FIGS. 2 and 6 , the upper case 78 is integrally equipped with a top wall 93 having a substantially rectangular plate shape; walls 94 (upper left side wall 94 a and upper right side wall 94 b ); and an upper rear wall 95 provided on the rear edge of the top wall 93 . The upper left side wall 94a and the upper right side wall 94b will be collectively referred to as "upper side wall 94" below. This structure forms a substantially rectangular shape viewed from the front side, and is open at the bottom and the front and rear sides.

The upper side wall 94 is bent downward from the width edge of the top wall 93 . Through-holes 116 are formed in each of the upper side walls 94 at positions opposed to each other in the width direction. The through hole 116 accepts the insertion of the drum shaft 34 of the photosensitive drum 28 . An electrode mounting part 113 is provided on the upper right side wall 94b for mounting an electrode plate 111 which will be described later. Additionally, the upper rear wall 95 curves diagonally downward and rearwardly from the rear edge of the top wall 93 . The upper rear wall 95 forms an obtuse angle with the top wall 93 , as shown in FIG. 2 .

The charger supporting unit 96 is disposed at the front and rear midpoints of the top wall 93 for supporting the charger 29 . The beam incident portion 97 is disposed on the top wall 93 in front of the charger supporting unit 96 for allowing the laser beam emitted from the scanning unit 19 to pass through. A cleaning support portion 98 for supporting the cleaning member 32 is also provided on the top wall 93 from the upper rear wall 95 to the rear of the charger support unit 96 .

As shown in FIG. 2 , the charger support unit 96 includes a front holding plate 99 and a rear holding plate 100 disposed at the front and rear midpoints of the top wall 93 . The front holding plate 99 and the rear holding plate 100 face each other in the front-rear direction with the grid 75 interposed therebetween.

The front holding plate 99 protrudes downward from the inner wall surface of the top wall 93 and extends in the width direction of the top wall 93 . The front holding plate 99 adjoins the grid 75 on the front side.

The rear holding plate 100 protrudes downward from the inner wall surface of the top wall 93 and extends parallel to the front holding plate 99 in the width direction of the top wall 93 . The rear holding plate 99 adjoins the grid 75 on its rear side. The amount by which the rear holding plate 100 protrudes from the top wall 93 is smaller than the protruding length of the front holding plate 99 .

Therefore, when the grid 75 is disposed between the front holding plate 99 and the rear holding plate 100 , the front holding plate 99 and the rear holding plate 100 clamp the grid 75 in the front-rear direction. The discharge wire 74 traverses between the upper side walls 94 and extends between the front retaining plate 99 and the rear retaining plate 100 .

The beam incident portion 97 includes a beam incident opening 101 formed in front of the charger supporting unit 96, having a substantially elongated rectangle in plan view, extending in the width direction; and a front incident plate 102 and After entering the plate 103, the beam incident opening 101 is formed therebetween.

The front injection plate 102 protrudes obliquely downward from the inner wall surface of the top wall 93 toward the rear side, and extends in the width direction of the top wall 93 . The front incident plate 102 is disposed on the front side of the beam incident opening 101 .

The rear injection plate 103 protrudes downward from the inner wall surface of the top wall 93 and extends in the width direction of the top wall 93 . The rear incident plate 103 is disposed on the rear side of the beam incident opening 101 . In addition, the rear entrance plate 1036 protrudes a shorter distance than the front entrance plate 102 .

In a side view, the light beam incident portion 97 has a substantially triangular shape and gradually narrows downward. When the scanning unit 19 emits a laser beam, the laser beam enters the beam incident opening 101 , passes between the front incident plate 102 and the rear incident plate 103 , and scans on the surface of the photosensitive drum 28 at high speed.

As shown in Figure 6, the cleaning support portion 98 includes an engaging portion 104 disposed near both lateral ends of the top wall 93 and the upper rear wall 95 for engaging the support plate 66 of the cleaning member 32; The support 105 at the interval. The engaging portion 104 includes a left engaging portion 104a and a right engaging portion 104b.

Each engaging portion 104 includes a three-sided member 109 provided on the upper rear wall 95 and exhibiting a rectangular shape with an open front side when viewed from the bottom; and front paws 110 facing the three-sided member 109 in the front-rear direction.

The three-sided member 109 consists of an inner side wall 106 extending in the front-rear direction on the inner side relative to the width direction of the three-sided member 109, an outer side wall 107 extending in the front-back direction on an outer side of the three-sided member 109 relative to the width direction, and connecting inner side walls. 106 and the connecting wall 108 at the rear edge of the outer side wall 107 are integrally formed.

In order for the support plate 66 to be supported, the inner side wall 106 is formed such that the lower edge of the inner side wall 106 follows the inclined slope of the upper rear wall 95 .

The outer side wall 107 faces the inner side wall 106 in the width direction. The outer side wall 107 protrudes further downward than the inner side wall 106 so as to contact the support plate 66 at both lateral edges thereof, thereby restricting lateral movement of the support plate 66 .

A notch portion 112 is formed in the outer side wall 107 of the right engaging portion 104b for engaging with an electrode plate 111 to be described later (see FIG. 8A ).

The connection wall 108 extends in the width direction and connects the rear edges of the inner side wall 106 and the outer side wall 107 together. The lateral center of the connection wall 108 protrudes slightly forward. A rear claw 114 protruding forward is formed on the protruding portion of the connection wall 108 (see FIGS. 8A and 8B ).

The front paw 110 is disposed in front of the rear paw 114 on the top wall 93 and faces the rear paw 114 in the front-rear direction. Front claw 110 has a hook shape for engaging support plate 66 (see FIGS. 8A and 8B ).

The supports 105 are disposed between the engaging portions 104 at the same intervals. Each support 105 protrudes from the inner wall surface of the upper rear wall 95 , and the bottom edge of the support 105 follows the inclined slope of the upper rear wall 95 .

An opening 115 is formed in the upper rear wall 95 along the width direction of the upper rear wall 95 . As shown in FIG. 4, each opening 115 penetrates the upper rear wall 95 in the thickness direction to form an elongated rectangular opening extending in the width direction. The openings 115 are spaced apart in the width direction, such as two openings 115 between each pair of adjacent supports 105 .

(2) Structure of cleaning components

As described above, the cleaning member 32 includes the cleaning brush 65 and the support plate 66, as shown in FIGS. 2 and 7 . The support plate 66 is formed of a conductive metal plate. As shown in FIGS. 8A and 8B , the support plate 66 consists of a flat plate portion 72 having an elongated rectangular shape extending along the width of the drum casing 76 (the axial direction of the photosensitive drum 28 ), and is disposed opposite to the flat plate portion 72 . The front curved portion 68 (the curved portion on the upper edge when mounted on the upper case 78 ) and the rear curved portion 69 (the curved portion on the lower edge when mounted on the upper case 78 ) and the two edges of the vertical direction perpendicular to the longitudinal direction. bending part) as a whole. The front curved portion 68 and the rear curved portion 69 extend in the longitudinal direction. As shown in FIG. 8B , the front bent portion 68 and the rear bent portion 69 are bent substantially in an L shape from the flat plate portion 72 to the rear. Therefore, in a cross-sectional view, the support plate 66 forms three sides of a rectangle opened rearward. As shown in FIG. 7 , a pair of engaged portions 67 are provided at both longitudinal ends of the support plate 66 . The right engaged portion 67 is as shown in FIG. 8A . The engaged portions 67 have the same structure as each other.

As shown in FIG. 8A , each engaged portion 67 is provided with a front engaging through hole 70 and a rear engaging through hole 71 respectively formed in the vertically facing front bent portion 68 and rear bent portion 69 . The front engaging through hole 70 is formed on the L-shaped bent portion where the flat plate portion 72 is bent to form the front bent portion 68 . Therefore, the front engaging through hole 70 is L-shaped when viewed from a side sectional view. At the engaged portion 67 , in the direction toward the front bent portion 68 , the free end of the rear bent portion 69 is further bent substantially into a V shape to form a V-shaped bent portion 69 a. A rear engagement through hole 71 is formed in the V-shaped bent portion 69a. Therefore, the rear engaging through hole 71 is V-shaped when viewed from a side sectional view.

The cleaning brush 65 is composed of a nonwoven cloth fixed to the surface of the flat plate portion 72 by a double-sided tape. A plurality of conductive bristles stand up from the nonwoven fabric at a position between the pair of engaged portions 67 , form a substantially rectangular shape as viewed from the side, and extend in the longitudinal direction of the flat plate portion 72 .

(3) Install the drum shell

(a) Install the cleaning member on the upper case

Next, a method of mounting the cleaning member 32 on the cleaning support portion 98 of the upper case 78 will be described with reference to FIGS. 8A to 10B .

As shown in FIG. 8A , first, the electrode plate 111 is mounted on the upper case 78 . The electrode plate 111 will be used to push the support plate 66 forward from the rear side of the support plate 66 .

As shown in FIG. 8A , the electrode plate 111 is a metal plate that extends in the width direction of the drum shell 76 and has a bent forwardly expanded bending part. The other longitudinal end of the electrode plate 111 (the outer end in the width direction of the drum shell 76) is inserted and fixed in the electrode mounting portion 113 provided on the upper right side wall 94b on the side of the electrode plate 111. The longitudinally middle portion is engaged in the notch portion 112 of the three-sided member 109 . Thus, the electrode plate 111 is mounted on the upper case 78 with its free longitudinal end bent in an arcuate shape in the front-rear direction.

The fixed longitudinal end of the electrode plate 111 is exposed outside the upper right side wall 94b in the width direction. When the drum cartridge 27 is installed in the main case 2, a terminal (not shown) provided on the main case 2 contacts the exposed longitudinal end of the electrode plate 111, so that a bias voltage is applied to the electrode plate 111 through the terminal.

Next, the support plate 66 is positioned to face the cleaning support portion 98 , as shown in FIGS. 9A and 9B , so that the front claw 110 is inserted into and engaged with the front engaging through hole 70 of the engaged portion 67 . Since the front engagement through hole 70 is engaged with the front claw 110, the support plate 66 is rotated about the front engagement through hole 70, and thus the rear curved portion 68 moves rearward. Thus, the rear engaging through-hole 71 of the engaged portion 67 is fitted on and engaged with the rear claw 114 of the engaging portion 104, as shown in FIGS. 10A and 10B . In this way, the support plate 66 is supported on the support 105 and the inner side wall 106 . As shown in FIG. 7, the support plate 66 is supported on the upper case 78 by the engaged portion 67 engaged with the engaging portion 104 at both longitudinal ends (both lateral ends of the drum shell 76), and because the support The plate 66 is mounted between the outer side walls 107, and the lateral movement of the support plate 66 is restricted.

When the support plate 66 is supported on the upper case 78, the free longitudinal ends of the electrode plates 111 contact the rear side of the support plate 66 and push the support plate 66 forward. As a result, when the drum cartridge 27 is installed in the main case 2 , terminals provided on the main case 2 can apply a bias voltage to the support plate 66 through the electrode plate 111 .

(b) Install the upper case on the lower case

As described above, the upper case 78 on which the cleaning member 32 is mounted is fitted on the lower case 77 .

With the charger 29 supported on the upper case 78, the transfer roller 31 supported on the lower case 77, and the main drum body 33 of the photosensitive drum 28 accommodated in the lower case 77, the upper case 78 is placed on the lower case. The top of the drum support unit 80 of the housing 77, as shown in FIG. 4, aligns the through hole 116 of the upper housing 78 with the through hole 89 of the lower housing 77 in the width direction. Subsequently, the drum shaft 34 is inserted through the main drum body 33 provided between the left through holes 116 , 89 and the right side through holes 116 , 89 . In this way, the upper case 78 and the lower case 77 are attached by the drum shaft 34 .

When the upper case 78 is attached to the lower case 77, the rear bent portion 69 of the support plate 66 contacts a positioning wall 92 (see FIG. 2 ) provided on the receiving plate 90 of the lower case 77, thereby being fixed relative to the photosensitive drum 28 The position of the cleaning brush 65. In addition, a collecting unit 118 is provided below the cleaning brush 65 .

In addition, the opening 115 of the upper housing 78 is located diagonally on the upper rear of the support plate 66 . An opening 115 is formed in the upper rear wall 95 . The support plate 66 faces the rear wall 95 , forming a space or gap between the support plate 66 and the rear wall 95 . The support plate 66 faces the opening 115 and no member is located in the space between the support plate 66 and the opening 115 . In other words, nothing obstructing any linear communication path between the support plate 66 and the opening 115 is positioned. The support plate 66 communicates with the outside of the housing through the opening 115 . In other words, the support plate 66 can be seen from the outside of the drum shell 76 through the opening 115 . More specifically, as shown in FIG. 11A , a boundary imaginary straight line 301 is defined to connect the lower edge of each opening 115 and the lower edge of the support plate 66 . Another boundary imaginary straight line 302 is defined to connect the upper edge of each opening 115 and the upper edge of the support plate 66 . For all openings 115 , no component is positioned within the space defined between boundary imaginary lines 301 and 302 . Note that for some openings 115, some components may be located in the space defined between the boundary imaginary lines 301 and 302, as long as at least one linear space connecting at least one opening 115 and the support plate 66 is partially reserved. This ensures that at least a portion of the support plate 66 can be viewed from the outside of the drum shell 76 through the at least one opening 115 .

In addition, the opening 115 is arranged diagonally above and behind the collection unit 118 , and the support plate 66 blocks communication between the opening 115 and the collection unit 108 .

The opening 115 is also arranged to face the charger 29 in the front-rear direction, enabling communication between the two. The support plate 66 is provided along the bottom of the communication path between the opening 115 and the charger 29 .

The opening 115 is also provided above the lower rear wall 87 of the lower housing 77 and diagonally to the upper rear of the cleaning member 32 . The opening 115 is also disposed diagonally in the lower front of the duct 120 when the drum shell 76 is installed into the main shell 2 .

(4) Operation and effect of drum shell and cleaning components

In the drum cartridge 27 described above, the cleaning member 32 faces the outside of the drum casing 76 through the opening 115 formed in the upper casing 78 . Therefore, the rear wall 95 of the drum casing 76 does not completely block the rear side of the cleaning member 32 opposite the side facing the photosensitive drum 28 , but the rear side of the cleaning member 32 directly communicates with the outside of the drum casing 76 through the opening 115 . Therefore, if the inside of the drum casing 76 reaches a high temperature, hot air is not accumulated in the drum casing 76 but is emitted to the outside of the drum casing 76 through the opening 115 . As a result, the cleaning member 32 can be cooled by a simple structure, the temperature rise of the cleaning member 32 is suppressed, and the toner deposited on the cleaning brush 65 is prevented from softening, thus preventing film formation on the photosensitive drum 28 .

In addition, the rear wall 95 covers the cleaning member 32 while making the cleaning member 32 face the outside of the drum casing 76 through the opening 115 . The cleaning member 32 is not directly exposed to the outside. Therefore, the cleaning member 32 can be protected by the rear wall 95 from directly contacting members outside the drum shell 76 . Therefore, it is possible to prevent the cleaning member 32 from being displaced due to contact with a member outside the drum casing 76 , thereby preventing damage to the photosensitive drum 28 .

Further, this structure of the cleaning member 32 can firmly support the cleaning brush 65 on the supporting plate 66, and at the same time, the fiber cleaning brush 65 can reliably scrape the paper dust off the photosensitive drum 28. Since the support plate 66 supports the cleaning brush 65 on the side opposite to the photosensitive drum 28 while directly facing the opening 115, this structure can prevent the paper dust captured by the cleaning brush 65 from escaping through the opening 115 and spreading to the bottom of the drum casing 76. outside. In addition, forming the support plate 66 with a thin metal plate improves the cooling effect.

Since the support plate 66 is supported on the drum shell 76 at both longitudinal ends thereof, the cleaning member 32 can also be reliably supported. More specifically, engaged portions 67 are provided at both longitudinal ends of the support plate 66 , and engaging portions 104 are provided on the upper case 78 for engaging the engaged portions 67 . Therefore, the support plate 66 can be reliably supported by engagement of the engaged portion 67 of the support plate 66 with the engagement portion 104 on the upper case 78 .

More specifically, each engaged portion 67 of the support plate 66 includes front engaging through holes 70 and rear engaging through holes 71 provided on both longitudinal ends of the supporting plate 66 and facing each other at a distance in the vertical direction. The engaging portion 104 of each engaged portion 67 includes a front claw 110 for engaging with the front engaging through hole 70 and a rear claw 114 for engaging with the rear engaging through hole 71 .

When the cleaning member 32 is installed, the front engaging through-holes 70 are first fitted on and engaged with the respective front paws 110 . Then, the support plate 66 is rotated backward around the front engaging through hole 70 until the rear engaging through hole 71 is fitted on and engaged with the rear claw 114 respectively, thereby supporting the support plate 66 on the upper housing 78 . Therefore, the support plate 66 can be reliably supported on the upper case 78 through a simple assembly process.

In addition, during installation, reliable engagement can be obtained with a simple structure including insertion of the front claw 110 in the front engagement through hole 70 and insertion of the rear claw 114 in the rear engagement through hole 71 .

Supporting the support plate 66 at both longitudinal ends on the drum shell 76 in this manner does not require any additional means for supporting the support plate 66 in areas other than the longitudinal ends. Therefore, with a simple structure, the support plate 66 can be reliably supported with respect to the opening 115 .

With a bias voltage applied to the support plate 66 through the electrode plate 111, the cleaning brush 65 can electrically attract paper dust. In addition, since the support plate 66 is opened on the side opposite to the cleaning brush 65 , the electrode plate 111 may be provided on this side for pushing the support plate 66 . Therefore, with a simple structure, a bias voltage can be reliably applied to the support plate 66 .

The support plate 66 is also arranged to block communication between the opening 115 and the collection unit 118 . Accordingly, the paper dust collected in the collecting unit 118 is prevented from being scattered through the opening 115 .

Since the support plate 66 is disposed at the bottom of the communication path between the opening 115 and the charger 29 , ozone generated by the charger 29 can be used to cool the support plate 66 while being exhausted through the opening 115 .

Since the rear holding plate 100 for holding the charger 29 protrudes a shorter length than the front holding plate 99 on the side closest to the opening 115 , air flow from the charger 29 to the opening 115 can be easily generated. As a result, ozone generated from the charger 29 can be more easily discharged through the opening 115 .

When the process cartridge 20 is installed in the main casing 2 of the laser printer 1, the fixing unit 21 and the photosensitive drum 28 are separated from each other in the horizontal direction, and the hot air generated from the heating roller 60 in the fixing unit 21 generates heat radiation and flows to the process. The photosensitive drum 28 of the cartridge 20 . Since the cleaning member 32 is disposed between the fixing unit 20 and the photosensitive drum 28 in a substantially horizontal direction, the cleaning member 32 is susceptible to temperature rise caused by hot air from the fixing unit 21 .

However, the process cartridge 20 includes a lower rear wall 87 extending to the rear of the cleaning member 32 on the lower housing 77 . Therefore, the lower rear wall 87 can prevent hot air generated from the heating roller 60 in the fixing unit 21 from contacting the cleaning member 32 . This structure can prevent the cleaning member 32 from being heated. This structure prevents film formation on the photosensitive drum 28 by suppressing the temperature rise of the cleaning member 32 in this way.

In addition to the lower rear wall 87, the inner rear wall 91 is also arranged in front of the upper and lower rear walls 87 of the lower casing 77 and is parallel to the lower rear wall 87, so the lower rear wall 87 and the inner rear wall 91 are in the front-rear direction, that is, from the outside to the inside. overlap in direction. In other words, the lower rear wall 87 and the inner rear wall 91 extend parallel to each other, and the inner rear wall 91 is located on the front side, that is, on the inner side with respect to the lower rear wall 87 . A space is formed between the lower rear wall 87 and the inner rear wall 91 . This gap acts as a thermally shielded cavity. Therefore, this structure further improves the heat shielding effect and further prevents the temperature rise of the cleaning member 32 .

As shown in FIG. 11B , a boundary imaginary straight line 303 is defined to connect the upper edge of the lower rear wall 87 and the upper edge of the area of the cleaning brush 65 that contacts the photosensitive drum 28 . Another boundary imaginary straight line 304 is defined to connect the lower edge of the lower rear wall 87 and the lower edge of the area of the cleaning brush 65 that contacts the photosensitive drum 28 . An inner rear wall 91 protrudes from the receiving plate 90 , the upper edge of the inner rear wall 91 being located between the boundary imaginary straight lines 303 and 304 . However, the protrusion amount of the inner rear wall 91 from the receiving plate 90 can be changed so that the upper edge of the inner rear wall 91 is higher than the boundary imaginary straight line 303 . The protrusion amount of the inner rear wall 91 can be freely changed as long as the upper edge of the inner rear wall 91 is above the boundary imaginary straight line 304 .

By arranging the cleaning member 32 to directly communicate with the outside of the drum casing 76 through the opening 115 without any member between the cleaning member 32 and the opening 115, the hot air generated in the fixing unit 21 is not trapped in the drum casing 76. , but diverge out of the drum shell 76 through the opening 115. Therefore, this structure suppresses the temperature rise of the cleaning member 32 and prevents film formation on the photosensitive drum 28 .

More specifically, by providing the opening 115 above the lower rear wall 87 in the lower housing 77, the lower rear wall 87 prevents hot air outside the drum housing 76 from impinging on the cleaning member 32, while hot air inside the drum housing 76 can pass through the opening. 115 diverges out of the drum shell 76 thereby effectively cooling the cleaning member 32 . As a result, this structure suppresses temperature rise of the cleaning member 32 and prevents filming on the photosensitive drum 28 .

By forming the opening 115 at the upper rear of the diagonal line of the cleaning member 32 , hot air rising around the cleaning member 32 can be efficiently discharged through the opening 115 . In the laser printer 1 , hot air generated from the heating roller 60 in the fixing unit 21 undergoes heat radiation and flows toward the photosensitive drum 28 of the process cartridge 20 . However, since the upstream end portion 120b of the duct 120 is disposed between the fixing unit 21 and the process cartridge 20, the duct 120 can guide hot air to the exhaust fan 119, and the exhaust fan 119 exhausts the hot air out of the main casing 2. Therefore, this structure further prevents the cleaning member 32 from becoming hot.

In addition, the opening 115 is located diagonally in the lower front of the duct 120 when the process cartridge 20 is installed in the main casing 2 . Therefore, hot air in the drum casing 76 can be guided through the duct 120 through the opening 115 and exhausted by the exhaust fan 119 , while hot air flowing from the fixing unit 21 to the photosensitive drum 28 can be guided through the duct 120 and exhausted by the exhaust fan 119 . Therefore, this structure effectively exhausts hot air from the main casing 2 .

The aforementioned laser printer 1 includes the drum cartridge 27 that can suppress the temperature rise of the cleaning member 32 to prevent film formation on the photosensitive drum 28 , thus achieving high-quality image formation.

3. Structure of positioning box

(1) A structure for positioning the drum cartridge and the developer cartridge in the front-back and vertical directions

11A and 12 show a mechanism provided on the drum casing 76 to position the developer cartridge 30 relative to the drum casing 76 . FIG. 11B shows how the developer cartridge 30 is mounted to the drum casing 76 . Fig. 11A, Fig. 11B and Fig. 12 correspond to Fig. 2, Fig. 3 and Fig. 5, respectively. However, in FIG. 11A, FIG. 11B and FIG. 12, in order to clearly illustrate the positioning of the drum casing 76 and the developer cartridge 30, several parts are omitted in the drawings. Fig. 13 is a perspective view of the developer cartridge 30 seen from the bottom side. 14 is a perspective view of the left end of the process cartridge 20 with the remainder removed, showing positioning of the drum casing 76 and the developer cartridge 30 in the paper width direction when the developer cartridge 30 is mounted on the drum casing 76. Structure.

A drum casing 76 that rotatably supports a cylindrical photosensitive drum 28 is detachably installed in the main frame 200 . The developing body casing 36 is detachably mounted on the drum casing 76 . In addition, when the developing body casing 36 is mounted on the drum casing 76, the developing roller 38 capable of carrying toner on its peripheral surface is rotatably supported in the developing body casing 36, so that the developing roller 38 and the photosensitive drum 28 parallel to each other.

As shown in FIGS. 11A and 12 , a developer cartridge installation unit 79 is formed in the drum casing 76 to the front side of the drum support unit 80 in which the photosensitive drum 28 is installed. The developer cartridge installation unit 79 is an internal space surrounded by a front bottom wall 81 and two front side walls 82a and 82b. As shown in FIG. 11B, the developer cartridge mounting unit 79 is configured to accommodate the developer cartridge 30 so that the outer peripheral surface 53a of the rubber roller body 53 in the developing roller 38 is contacted by the thin layer of toner carried on the outer peripheral surface 53a. The outer peripheral surface 33 a of the photosensitive drum 28 .

As shown in FIGS. 11A and 12 , a pair of positioning notches 131 are formed in a pair of side walls 86 a and 86 b , respectively. Each positioning notch 131 extends in a direction toward the metal drum shaft 34 of the photosensitive drum 28 installed in the drum casing 76 . As shown in FIG. 11B , when the developer cartridge 30 is mounted on the drum casing 76 , the positioning notch 131 is used to accommodate the roller shaft 52 of the developing roller 38 . Each positioning notch 131 has an end surface 132 facing the metal drum shaft 34 of the photosensitive drum 28 and with which the roller shaft 52 of the developing roller 38 contacts when the developer cartridge 30 is installed in the drum casing 76 . The positioning notch 131 and the end surface 132 are formed to set the relative positions of the photosensitive drum 28 and the developing roller 38 in front-rear and vertical directions.

(2) Structure for positioning the developing body case and the developing roller in the paper width direction

As shown in FIG. 11B , a pair of pins 207 stand upright from the left end on the roller shaft 52 of the developing roller 38 with respect to the lateral direction. The pin 207 stands up from a prescribed position on the roller shaft 52 near the left edge thereof. When the developing roller 38 is mounted in the developing body housing 36, the left edge of the roller shaft 52 protrudes outward (leftward) from the left side wall 143a, and the right edge of the roller shaft 52 projects outward (toward the left) from the right side wall 143b. Right) highlighted. The pin 207 contacts the inner side surface of the left side wall 143a, thus setting the position of the developing roller 38 relative to the developing body housing 36 in the paper width direction. Note that when the developing body housing 36 is mounted on the developer cartridge mounting unit 79 , the left side wall 143 a of the developing body housing 36 faces the left side wall 156 a of the drum housing 76 .

(3) Structure for positioning the drum cartridge and developer cartridge in the paper width direction

As shown in FIG. 12 , an engaging unit 152 is formed on the left end of the bottom wall 151 in the paper width direction. The engaging unit 152 is located near the left side wall 156a. The engaging unit 152 is formed on the left side of the left edge of the paper inlet 133 in the paper width direction. The engaging unit 152 is composed of ribs 153 and 154 erected upward from the bottom wall 151 and substantially parallel to the side wall 156 . A gap 155 of prescribed width is formed between the ribs 153 and 154 in the width direction of the drum cartridge 76 . Each of the ribs 153, 154 has a plate shape extending perpendicular to the paper width direction and having a certain thickness in the paper width direction.

As shown in FIG. 13 , a positioning rib 145 is formed on the left side end of the bottom wall 141 of the developing body housing 36 in the paper width direction. The positioning rib 145 is positioned near the side cover 146 provided outside the left side wall 143a in the paper width direction. The coupling member 147 is provided on the side cover 146 . An input shaft (not shown) provided on the main frame 200 (see FIG. 15 ) may be inserted into the coupling member 147 . When the developing body casing 36 is installed in the laser printer 1 and the input shaft is inserted into the coupling member 147, the driving force from the motor (not shown) provided on the main frame 200 can be transmitted to the developer cartridge through the coupling member 147. 30 is used to rotate the developing roller 38 . The positioning rib 145 is formed near the coupling member 147 . The positioning rib 145 is in the shape of a plate extending perpendicular to the paper width direction and having a certain thickness in the paper width direction.

FIG. 14 shows how the developer cartridge 30 is mounted on the drum casing 76. As shown in FIG. As shown in FIG. 14 , the gap 155 between the ribs 153 and 154 in the paper width direction and the thickness of the positioning rib 145 are set so that the positioning rib 145 can fit into the gap 155 with a prescribed fitting tolerance. By fitting the positioning rib 145 into the engaging unit 152, when the developer cartridge 30 is installed in the drum casing 76 (drum cartridge 27), it is possible to position the drum casing 76 and the developing body relative to each other in the paper width direction. Housing 36.

In other words, positioning ribs 145 are formed on the developing body casing 36 for positioning the developing body casing 36 relative to the drum casing 76 in the paper width direction. Further, in order to position the developing body housing 36 relative to the drum housing 76 in the paper width direction, an engaging unit 152 is formed on the drum housing 76 to engage with the positioning rib 145 .

As shown in FIG. 14, the engaging unit 152 and the positioning rib 145 are disposed almost directly below the developing roller 38 (ie, near the rotational shaft 52 of the developing roller 38).

(4) The structure of positioning drum cartridge and photosensitive drum

FIG. 15 is a horizontal cross-sectional view showing how the drum shell 76 is installed in the main frame 200. As shown in FIG. In FIG. 15, the developer cartridge 30 (see FIG. 1) installed in the developer cartridge installation unit 79 is omitted from the figure.

As shown in FIG. 15 , a drum gear 241 is provided at the left end of the photosensitive drum 28 . An extension pipe 242 is formed on the right side surface of the drum gear 241 . The drum gear 241 is fixed to the photosensitive drum 28 by inserting the extension tube 242 into the left end of the main drum body 33 with a prescribed fit tolerance so that the drum gear 241 cannot rotate relative to the main drum body 33 . The drum gear 241 is mounted on the main drum body 33 such that the right side surface of the drum gear 241 is in contact with the left end surface 232 of the main drum body 33 . The drum gear 241 is connected to a main driving gear (not shown) provided on the main frame 200 so that driving force can be transmitted to the photosensitive drum 28 through the drum gear 241 .

The end surface 243 on the left side of the drum gear 241 has a predetermined flatness. As shown in FIGS. 12 and 15 , a pair of protrusions 201 are formed in the left side wall 156 a (more specifically, the rear left side wall 86 a ) at positions facing the end surface 243 of the drum gear 241 . Each protrusion 201 has an end face 202 facing the drum gear 241 and formed with prescribed flatness. A through hole 89 is formed between the pair of protrusions 201 .

The flange portion 234 is mounted on the right end of the main drum body 33 and is in contact with the end surface 233 on the right end of the main drum body 33 .

A partition 246 interposed between the two felt members 245 is provided on the outer side (right side) of the flange portion 234 in the paper width direction. Accordingly, the felt member 245 is inserted between the flange portion 234 and the partition 246 and between the partition 246 and the right side wall 156b (the right side wall 86b). The felt member 245 is elastically compressible in the paper width direction. A spring (not shown) provided inside the main drum body 33 urges the main drum body 33 and the drum gear 241 to the left. Therefore, the photosensitive drum 28 is set in the drum casing 76 with the end surface 243 in contact with the end surface 202 facing the protrusion 201 of the drum gear 241 . By the contact between the end surface 202 and the end surface 243, the photosensitive drum 28 can be positioned relative to the drum casing 76 in the paper width direction.

Specifically, the position of the end surface 202 of the protrusion 201 with respect to the engagement unit 152 and the position of the positioning rib 145 with respect to the inner side surface of the left side wall 143 a in the paper width direction are set so that when the developer cartridge 30 is housed in the drum casing 76 When in the developer cartridge mounting unit 79, the entire length of the effective latent image forming area 236 is successfully made to fall within the entire length of the effective image forming area on the outer peripheral surface 53a with respect to the paper width direction. Therefore, the pair of effective area boundaries 235 of the effective latent image forming area 236 successfully falls within the effective image forming area on the outer peripheral surface 53 a with respect to the paper width direction.

(5) Structure of positioning mechanism for main frame and process cartridge

As shown in FIG. 15 , the left side frame 211 and the right side frame 221 are fixed to the inner side surface of the main frame 200 .

A guide groove 213 is formed in the left side frame 211 disposed to face the left side wall 156 a of the drum shell 76 when the drum shell 76 is mounted in the main shell 2 . Specifically, the guide groove 213 is formed in an upper portion of the left side frame 211 on the inner side in the paper width direction. When viewed from the front side (from the bottom of FIG. 15 ), the guide groove 213 is rectangular and extends in the sheet conveying direction (front-rear direction). Side surfaces of the guide groove 213 include an introduction surface 217 at the front running parallel to the main frame 200 and the paper conveying direction, and an inclined surface 218 formed on the rear side of the introduction surface 217 inclined inwardly in the paper width direction. A recess 214 is formed at the end of the rear side guide groove 213 of the inclined surface 218 for receiving the drum shaft 34 of the photosensitive drum 28 .

A rear end 215 constituting the rear surface of the recess 214 forms one end of the guide groove 213 on the rear surface side. Therefore, the positions of the drum casing 76 and the photosensitive drum 82 relative to the main frame 200 in the paper width direction are determined by the outer peripheral surface of the metal drum shaft 34 of the photosensitive drum 28 contacting the rear end 215 .

The depression 214 has a side end surface 216 forming an end surface (left end surface) of the depression 214 in the paper width direction. The side end surface 216 has a predetermined flatness. When the axial end 231 of the metal drum shaft 34 contacts the side end surface 216, the positions of the drum casing 76 and the photosensitive drum 28 relative to the main frame 200 in the paper width direction are determined. Therefore, the mechanism for determining the relative position of the main frame 200 and the drum casing 76 in the paper width direction parallel to the rotation axis of the photosensitive drum 28 consists of the left side frame 211 having the recess 214 and the left side wall 86a having the protrusion 201 constitute.

On the drum casing 76, the engaging unit 152 is positioned relative to the end surface 202 of the protruding portion 201 in the paper width direction, ensuring that the engaging unit 152 is positioned at the drum gear 241 and the left effective area when the photosensitive drum 28 is mounted on the drum casing 76. between borders 235a. This also ensures that the bonding unit 152 is located outside (left side) of the effective latent image forming area 236 . In addition, on the developing body casing 36, the positioning rib 145 is positioned relative to the inner side surface of the positioning rib 145 in the paper width direction so that the left side wall 143a is positioned outside the effective image forming area on the outer peripheral surface 53a of the developing roller 38 (i.e. left). Therefore, when the developing body casing 36 is mounted on the drum casing 76 , it is ensured that the engaging unit 152 and the positioning rib 145 are disposed outside the effective latent image forming area 236 and the effective image forming area. The engagement unit 152 and the positioning rib 145 are provided near the left side frame 211 and the left side wall 156a, constituting a positioning mechanism for positioning the main frame 200 and the drum casing 76 relative to each other.

A guide groove 222 is formed in the right side frame 221 facing the right side wall 156 b of the drum shell 76 when the drum shell 76 is mounted in the main shell 2 . Specifically, the guide groove 222 is formed in an upper portion of the right side frame 221 on the inner side in the paper width direction. The guide groove 222 has a rectangular shape when viewed from the front side and extends in the paper conveying direction. The inner surface of the guide groove 222 extends parallel to the main frame 222 and the paper conveying direction to the rear end surface 223 on the rear side of the guide groove 222 . In other words, the guide groove 222 has no portions corresponding to the inclined surface 218 and the depression 214 of the guide groove 213 . The leaf spring 225 is disposed at one end of the guide groove 222 near the rear surface thereof. The leaf spring 225 pushes the metal drum shaft 34 of the photosensitive drum 28 inwardly (leftward) in the paper width direction so as to keep the shaft end 231 in contact with the side end surface 216 . Further, the main drum body 33 is electrically connected to the grounded right side frame 221 and the main frame 200 through the leaf spring 225 and the metal drum shaft 34 .

The left side frame 211 also includes a plate-shaped lower guide groove plate 219 extending inwardly in the paper width direction and disposed below the guide groove 213 to define a bottom surface of the guide groove 213 thereon. Similarly, the right side frame 221 includes a plate-shaped lower guide groove plate 224 extending inwardly in the paper width direction and disposed below the guide groove 222 to define a bottom surface of the guide groove 222 thereon. The lower guide groove plates 219 and 224 face each other at the same height. The lower guide grooves 219 and 224 serve to support the outer peripheral surface on the metal drum shaft 34 of the photosensitive drum 28 when the drum casing 76 is installed in the main frame 200 and the drum casing 76 is slid backward. By leaning the metal drum shaft 34 of the photosensitive drum 28 against the lower guide groove plates 219 and 224 while the metal drum shaft 34 is in contact with the rear end 215 of the guide groove 213 and the rear end surface 223 of the guide groove 222, the drum casing 76 and the photosensitive drum 28 is fixed in position relative to the main frame 200 in the height direction.

(6) Operation and effect of positioning drum cartridge and developer cartridge, drum cartridge and photosensitive drum, and main frame and process housing relative to each other

As shown in FIG. 14 , the drum casing 76 and the developing body casing 36 can be easily and reliably positioned relative to each other in the paper width direction by engaging the positioning rib 145 in the engaging unit 152 .

As shown in FIGS. 12 and 13 , an engaging unit 152 and a positioning rib 145 are formed at left ends of the drum housing 76 and the developing body housing 36 in the paper width direction, respectively. This structure allows reduction of dimensional tolerances due to the small distances from the reference surfaces (the left side wall 156a of the drum housing 76 and the left side wall 143a of the developing body housing 36) to the engaging unit 152 and to the positioning rib 145. That is, the distance from the left side wall 143a to the positioning rib 145 is small. The distance from the left side wall 156a to the coupling unit 152 is small. Therefore, it is possible to precisely position the drum casing 76 with respect to the developer cartridge 30 .

Here, the distance from the position formed by the positioning rib 145 and the engaging unit 152 to the reference surfaces (the left side wall 156 a and the left side wall 143 a ) on the developer accommodating unit 79 and the developing body housing 36 is smaller than the width of the drum housing 76 and The width of the developer cartridge 30. More specifically, the distance from the position where the positioning rib 145 and the engaging unit 152 are formed to the reference surfaces (the left side wall 156 a and the left side wall 143 a ) is less than half the width of the drum casing 76 and the width of the developer cartridge 30 . Therefore, a small dimensional tolerance can be given to the size from the position where the positioning rib 145 and the engaging unit 152 are formed to the reference surface (the left side wall 156 a and the left side wall 143 a ).

The thickness of the positioning rib 145 and the distance between the ribs 153 and 154 in the joint unit 152 are much smaller than the width of the developer cartridge accommodating unit 79 and the width of the developer cartridge 30 . Accordingly, a play gap may be reduced when the positioning rib 145 and the engaging unit 152 are engaged.

As shown in FIG. 14 , the engagement unit 152 is constituted by a pair of ribs 153 and 154 facing each other across a narrow gap 155 . This structure can reduce the fitting tolerance of the positioning rib 145 in the gap 155, and can ensure that the developer cartridge 30 is reliably installed on the drum casing 76, and the drum casing 76 and the developing body casing 36 are aligned in the paper width direction. There is no relative movement between them. Therefore, it is possible to set the outside of the drum casing 76 and the developing body casing 36 in the paper width direction with a relatively large lateral gap between the side wall 156 (see FIG. 12 ) and the opposite side wall 143 (see FIG. 13 ). size. Therefore, the developer cartridge 30 can be mounted and accurately positioned on the drum casing 76 smoothly and reliably.

By forming the engagement unit 152 and the positioning rib 145 (see FIG. 14 ) constituting a positioning mechanism for positioning the drum shell 76 relative to the main frame 200 at positions near the left side frame 211 and the left side wall 156a, the drum shell 76 and the developing body casing 36 are positioned relative to each other. This positioning is performed by engaging the positioning rib 145 with the engaging unit 152 in the vicinity of the coupling member 147 (see FIG. 13 ) transmitting the rotational driving force and the drum gear 241 . In addition, the positioning rib 145 is provided near the rotation axis of the developing roller 38 .

In order to maintain a stable mounting state of the developer cartridge 30 on the drum casing 76, this structure can suppress side-to-side swinging (in a direction parallel to the paper width direction) generated in the developing body casing 36 when a rotational driving force is transmitted. ). Therefore, wear and damage to the engagement unit 152 and the positioning rib 145 can be suppressed. Further, the main frame 200, the drum casing 76 and the developing body casing 36 can be precisely positioned relative to each other.

The photosensitive drum 28 and developing roller 38 are positioned in the paper width direction so that the effective latent image forming area 236 on the photosensitive drum 28 substantially coincides with the effective image forming area on the peripheral surface 53a of the developing roller 38 in the paper width direction. Therefore, the charged toner of a prescribed density and a prescribed charge amount carried on the peripheral surface 53a of the developing roller 38 can be reliably supplied to the entire width of the electrostatic latent image formed on the peripheral surface of the photosensitive drum 28, thereby using the toner The powder properly develops the electrostatic latent image.

The bonding unit 152 is formed outside the effective latent image forming area 236 . That is, the bonding unit 152 is on the left side of the left active area boundary 235a. The splicing unit 152 is on the left side of the left paper inlet 133 . The positioning rib 145 is formed on the outer side (left side) of the effective image forming area of the developing roller 38 . Therefore, the engagement unit 152 and the positioning rib 145 can be securely provided at the left ends of the drum casing 76 and the developing body casing 36 , respectively, in the paper width direction. Therefore, the drum casing 76 and the developing body casing 36 can be effectively positioned in the paper width direction while constituting a paper conveyance path that enables the paper to be conveyed smoothly in the effective latent image forming area and the effective image forming area.

Although the present invention has been described in detail with reference to the above-mentioned aspects thereof, it is obvious that those skilled in the art can make various changes and modifications therein without departing from the spirit of the present invention.

(a) For example, the above-described positioning mechanism can be applied to various types of image forming apparatuses including laser printers. Additionally, the drum housing 76 may be configured to house and support only the photosensitive drum 28 without including other components such as the developing roller 38 . Also, the drum casing 76 configured to house and support the photosensitive drum 28 may form part of the main frame 200 . In other words, the drum shell 76 may be fixed to the main frame 200 . The developer cartridge 30 may be detachably mounted on the main frame 200 .

(b) The engaging unit 152 is not limited to a structure constituted by a plurality of ribs 153 and 154 . The coupling unit 152 may be modified to have other various structures. For example, the coupling unit 152 may be constituted by a recess or a through hole formed on the bottom wall 151 .

(c) In the above description, the engaging unit 152 is formed on the drum casing 76 and the positioning rib 145 is formed on the developing body casing 36 . However, the engaging unit 152 may be formed on the developing body casing 36 while the positioning rib 145 is formed on the drum casing 76 . Also, in this case, the engaging unit 152 may be formed of a recess, a through hole, a plurality of ribs, or other forms.

(d) Although the engaging unit 152 and the positioning rib 145 are positioned at the left end in the paper width direction in the above description, the positions of the engaging unit 152 and the positioning rib 145 are not limited to these positions.

(e) In the above description, when the positioning rib 145 is engaged in the engaging unit 152 to position the drum casing 76 and the developing body casing 36 relative to each other in the sheet width direction, the photosensitive drum 28 and the developing roller 38 are positioned on the sheet. The width directions are positioned relative to each other. However, the combination of the positioning rib 145 and the engaging unit 152 may be modified to position the drum casing 76 and the developing body casing 36 relative to each other in the paper width direction, but not to position the photosensitive drum 28 and the developing body casing 36 relative to each other in the paper width direction. Roller 38.

(f) A plurality of inner rear walls 91 may be erected vertically from the receiving panel 90 in front of the lower rear wall 87 .

(g) Also, instead of the plurality of openings 115 in the above description, at least one opening 115 may be formed in the upper rear wall 95 . Accordingly, the support plate 66 faces the rear wall 95 , a space or gap is formed between the support plate 66 and the rear wall 95 , and communicates with the outside of the housing through the at least one opening 115 . At least a portion of the support plate 66 faces the at least one opening 115 . At least a portion of the support plate can be seen from the outside of the drum shell 76 .

(h) The cleaning member 32 or the opening 115 may not be provided on the drum shell 76 .

(i) The positioning mechanism for positioning the developing body casing 36 with respect to the drum casing 76 and the positioning mechanism for positioning the drum casing 76 with respect to the main frame 2 may not be limited to the above-mentioned structures.

Claims (7)

1. A process cartridge used in an image forming apparatus, characterized in that the process cartridge comprises: a drum casing housing a photosensitive drum carrying a developer image, the photosensitive drum being formed in a cylindrical shape and rotatably supported by the drum casing about its rotational axis; and a developing body housing detachably mounted on the drum housing; Wherein, any one of the drum casing and the developing body casing has a rib formed in a plate shape and extending in a direction perpendicular to the rotation axis of the photosensitive drum; and Wherein the other of the drum casing and the developing body casing has a positioning unit engaged with the rib, which positioning unit positions the drum casing and the developing body casing with each other in a direction parallel to the rotation axis of the photosensitive drum. . 2. The process cartridge according to claim 1, wherein said developing body housing rotatably supports a developing roller and is capable of accommodating developer, Among them, the photosensitive drum forms an electrostatic latent image thereon; The developing roller is cylindrical and configured to carry a developer on its peripheral surface to develop the electrostatic latent image into a developer image; and When the developer cartridge is mounted on the process cartridge, the developing roller is parallel to the photosensitive drum and the photosensitive drum faces each other. 3. The process cartridge according to claim 2, wherein one of the rib and the positioning unit formed on the developing body casing is disposed near the rotational axis of the developing roller. 4. The process cartridge according to claim 2, wherein when the developer cartridge is installed on the drum casing, the one of the rib and the positioning unit formed on the developing body casing is relatively to the developing body casing. The axial positioning of the roller is outside the area of the developing roller that faces the electrostatic latent image formed on the photosensitive drum. 5. The process cartridge according to claim 4, further comprising a driving force transmitting unit that transmits a rotational driving force to the developing roller; Wherein, the one of the rib and the positioning unit formed on the developing body casing is disposed near the driving force transmission unit. 6. An image forming device, characterized in that the image forming device comprises: main frame; a process cartridge detachably mounted in the main frame, the process cartridge including a drum casing housing a photosensitive drum carrying an electrostatic latent image thereon, and being formed in a cylindrical shape around its rotational axis by the drum shell is rotatably supported and has an electrostatic latent image formed thereon; and a developing body casing detachably mounted on the drum casing and rotatably supporting a developing roller parallel to and facing the photosensitive drum, the developing roller having a cylindrical shape and being configured to carry a developer on its peripheral surface to develop the electrostatic latent image into a developer image, Wherein, the main frame and the drum shell include a positioning mechanism, and the positioning mechanism positions the drum shell in a direction parallel to the rotation axis of the photosensitive drum relative to the main frame; Either one of the drum casing and the developing body casing has a rib configured to position the drum casing and the developing body casing with each other in a direction parallel to the rotation axis of the photosensitive drum; The other of the drum casing and the developing body casing has a positioning unit configured to engage with the rib to align the drum casing and the developing body casing in a direction parallel to the rotation axis of the photosensitive drum. Mutual positioning. 7. The image forming apparatus according to claim 6, wherein one of the rib and the engaging portion formed on the drum casing is provided near the positioning mechanism.

Images