JP2006317623A - Developing cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing cartridge where the opening part of a housing is reinforced with a simple constitution, and also, a distance between a developer carrier and the opening part is accurately secured, to provide a process cartridge equipped with the developing cartridge, and to provide an image forming apparatus. <P>SOLUTION: In the developing cartridge 30, a reinforcement part 80 is arranged on the lower edge part 68 of the housing opening part 94 of the box type housing 36 whose rear side is open. The reinforcement part 80 extends along the lower edge part 68, and the cross section in a direction orthogonal to the width direction is formed to a U-shape with its the rear side opened. The lower edge part 68 of the housing opening part 94 of low strength is effectively reinforced by the reinforcement part 80. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a laser printer, and a developing cartridge and a process cartridge provided in the image forming apparatus.

An electrophotographic image forming apparatus such as a laser printer is provided with a photosensitive drum on which an electrostatic latent image is formed, and a developing cartridge for developing the electrostatic latent image formed on the photosensitive drum is provided. It is attached detachably.
The developing cartridge includes a box-shaped casing in which an opening is formed so as to face the photosensitive drum, and the casing is formed with a toner storage chamber for storing toner, and the toner storage The developing roller carrying the toner accommodated in the chamber is rotatably supported so as to be exposed from the opening (see, for example, Patent Document 1).

Then, when the developing roller exposed from the opening of the housing comes into contact with the photosensitive drum, the toner carried on the developing roller is supplied to the photosensitive drum, and the electrostatic latent image is developed.
JP 2001-5288 A

  However, as described above, the housing of the developing cartridge is formed with an opening to expose the developing roller. However, the peripheral edge of the opening is inevitably low in strength, so that the developing cartridge can be attached and detached. When gripping the vicinity of the opening in the housing, the housing is deformed (bent), the developing roller is damaged, or the toner leaks between the developing roller and the housing. There is.

  An object of the present invention is to provide a developing cartridge that can reinforce the opening of the housing with a simple configuration, and that can ensure the interval between the developer carrier and the opening with high accuracy. Another object of the present invention is to provide a process cartridge and an image forming apparatus equipped with the developing cartridge.

In order to achieve the above object, the invention described in claim 1 is a developing cartridge, wherein a developer carrying member carrying a developer and an opening are formed, and the developer carrying is carried out so as to be exposed from the opening. It is provided with the housing | casing which supports a body, and the box-shaped reinforcement part provided so that it may extend along the edge part of the said opening part, and reinforcing the said edge part, It is characterized by the above-mentioned.
According to such a configuration, the casing is provided with the box-shaped reinforcing portion extending along the edge portion of the opening portion for exposing the developer carrying member. Therefore, the edge of the opening having low strength can be effectively reinforced. Further, since the reinforcing portion is formed in a box shape, the thickness of the casing constituting the reinforcing portion and the thickness of the casing constituting each portion other than the reinforcing portion can be made uniform. Sinks are less likely to occur during molding on the facing surface facing the surface. As a result, the opening of the housing can be reliably reinforced, and the interval between the developer carrier and the opening can be ensured with high accuracy.

According to a second aspect of the present invention, in the first aspect of the present invention, the reinforcing portion has a U-shaped cross section in a direction orthogonal to a direction extending along the edge of the opening. It is characterized by having.
According to such a structure, since the cross section of the reinforcement part is formed in U shape, a box shape can be formed easily. Therefore, the opening of the housing can be reliably reinforced while facilitating molding.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the developer carrier is a developing roller, and the reinforcing portion extends along an axial direction of the developing roller. It is characterized by being arranged.
According to such a structure, the reinforcement part is arrange | positioned so that it may extend along the axial direction of a developing roller in the edge part of the opening part of a housing | casing. Therefore, even when the vicinity of the opening in the casing is gripped, the casing can be prevented from being deformed, the developing roller is damaged, and toner leakage occurs between the developing roller and the casing. It can be effectively prevented.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, a gap between the edge and the developer carrying member is blocked at an edge of the opening. As described above, a film member for preventing leakage of the developer from the gap is provided.
According to such a configuration, the film member can block the gap between the edge of the opening and the developer carrier, and prevent leakage of the developer from the gap. In addition, the reinforcing portion provided at the edge is formed in a box shape, and sink marks during molding are unlikely to occur on the facing surface facing the developer carrying member, so that the facing surface is formed smoothly. can do. As a result, the film member can be adhered to the smooth opposing surface, and the film member can be attached with high accuracy.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the edge of the opening has a plurality of steps in a cross section in a direction orthogonal to a direction extending along the edge of the opening. In the direction in which the developer leaks from the opening, the film member has a downstream edge of a step on the upstream side of the step on the upstream side of the step on the most downstream side. It is characterized by being affixed as a standard.

  When the cross section of the edge is formed in a simple rectangular shape, when the film member is pasted on the basis of the downstream edge of the edge, the downstream edge of the edge and the edge of the film member And the film member is easily peeled off from the edge. On the other hand, if the film member is attached to the upstream side of the downstream edge of the end portion, the film member can be made difficult to peel off from the edge portion, but the standard for attaching the film member becomes unclear. And a film member cannot be reliably stuck along an edge, but the attachment accuracy of a film member falls.

  However, according to such a configuration, the cross-section of the edge portion is formed in a stepped shape including a plurality of steps, and the film member has a step on the upstream side of the step on the upstream side of the step on the most downstream side. It is pasted on the basis of the downstream side edge. Therefore, since a film member is stuck to the level | step difference of an upstream rather than the level | step difference of the most downstream side, a film member can make it difficult to peel from an edge part. And since the film member is affixed on the upstream level | step difference on the basis of a downstream edge, the film member can be reliably affixed along an edge.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the developer carrying member protrudes from the inside of the casing through the opening to the outside of the casing. It is characterized by being supported by the casing.
According to such a configuration, since the developer carrying body protrudes from the inside of the housing through the opening, the electrostatic latent image for developing the developer carrying body with the developer carrying body is formed. It is possible to dispose the image carrier in an oblique direction so that a portion other than the most protruding portion is in contact with the existing image carrier. Therefore, the degree of freedom of device layout can be increased and the size of the device can be reduced.

The invention according to claim 7 is the developer image formed in the housing according to any one of claims 1 to 6 by the developer carried on the developer carrier on the casing. A guide member for guiding the recording medium to which the image is transferred is provided so as to be continuous from the reinforcing portion.
According to such a configuration, since the guide member for guiding the recording medium is provided so as to continue from the reinforcing portion, the recording medium can be further reinforced while the opening of the housing can be further reinforced. It can guide smoothly.

The invention according to claim 8 is the invention according to claim 7, wherein a plurality of the guide members are provided at intervals in a direction intersecting a direction in which the reinforcing portion extends. It is said.
According to such a configuration, a plurality of guide members are provided at a distance from each other in the direction intersecting the direction in which the reinforcing portion extends, so that the recording medium is reduced while reducing the frictional resistance between the recording medium and the guide member. It can be surely guided.

A ninth aspect of the present invention is a process cartridge, wherein the developing cartridge according to any one of the first to eighth aspects and the developer carrying member are disposed opposite to each other, and development from the developer carrying member is performed. And an image carrier that carries an electrostatic latent image that is visualized as a developer image upon supply of the developer.
According to such a configuration, since the developing cartridge in which the opening of the casing is reinforced is provided, the rigidity of the process cartridge can be improved.

The invention according to claim 10 is the invention according to claim 9, wherein the developer carrier is in contact with a portion other than a portion that protrudes most in the direction from the inside of the housing to the outside of the housing. Further, the image bearing member is disposed opposite to the image carrier from an oblique direction.
According to such a configuration, the developer carrying member is disposed so as to face the image carrying member in an oblique direction so that a portion other than the most protruding portion contacts the image carrying member. Therefore, the degree of freedom of device layout can be increased and the size of the device can be reduced.

According to an eleventh aspect of the present invention, there is provided an image forming apparatus, wherein the process cartridge according to any one of the first to tenth aspects is detachably provided.
According to such a configuration, since the process cartridge with improved rigidity is provided, the rigidity of the image forming apparatus can be improved.
According to a twelfth aspect of the present invention, there is provided an image forming apparatus, wherein the developing cartridge according to any one of the first to eighth aspects is detachably provided.

  According to such a configuration, since the developing cartridge with improved rigidity is provided, the rigidity of the image forming apparatus can be improved.

According to the first aspect of the present invention, it is possible to reliably reinforce the opening of the housing, and to ensure a sufficient interval between the developer carrier and the opening.
According to the second aspect of the present invention, the opening of the housing can be reliably reinforced while facilitating molding.
According to the third aspect of the present invention, even when the vicinity of the opening in the casing is gripped, the casing can be prevented from being deformed, the developing roller can be damaged, or the developing roller and the casing can be prevented from being damaged. It is possible to effectively prevent toner leakage from the gap.

According to the fourth aspect of the present invention, the developer can be prevented from leaking. In addition, the film member can be attached with high accuracy.
According to invention of Claim 5, a film member can make it difficult to peel from an edge. And a film member can be reliably stuck along an edge.
According to the invention described in claim 6, the degree of freedom of the device layout can be increased, and the size of the device can be reduced.

According to the seventh aspect of the invention, the recording medium can be smoothly guided while the opening of the housing can be further reinforced.
According to the eighth aspect of the invention, it is possible to reliably guide the recording medium while reducing the frictional resistance between the recording medium and the guide member.
According to the ninth aspect of the invention, the rigidity of the process cartridge can be improved.

According to the invention described in claim 10, the degree of freedom of the device layout can be increased, and the size of the device can be reduced.
According to the invention of the eleventh aspect, it is possible to improve the rigidity of the image forming apparatus.
According to the twelfth aspect of the present invention, it is possible to improve the rigidity of the image forming apparatus.

1. 1 is a side sectional view showing an embodiment of a laser printer as an image forming apparatus of the present invention, and FIG. 2 is a side sectional view of a process unit of the laser printer shown in FIG. .
As shown in FIG. 1, the laser printer 1 includes a main body casing 2, a feeder unit 4 for feeding paper 3 serving as a recording medium housed in the main body casing 2, and fed paper 3 is provided with an image forming section 5 for forming an image.

(1) Main Body Casing An attachment / detachment opening 6 for attaching / detaching a process cartridge 20 described later is formed on one side wall of the main body casing 2, and a front cover 7 for opening / closing the attachment / detachment opening 6 is provided. ing. The front cover 7 is rotatably supported by a cover shaft 8 inserted through a lower end portion thereof. Thus, when the front cover 7 is closed with the cover shaft 8 as a fulcrum, the attachment / detachment opening 6 is closed by the front cover 7, and when the front cover 7 is opened with the cover shaft 8 as a fulcrum, the attachment / detachment opening 6 is opened. The process cartridge 20 can be attached to and detached from the main casing 2 through the attachment / detachment port 6.

In the following description, in a state where the process cartridge 20 is mounted on the main casing 2, the side on which the front cover 7 is provided is referred to as “front side”, and the opposite side is referred to as “rear side”.
(2) Feeder unit The feeder unit 4 includes a paper feed tray 9 that is detachably attached to the bottom of the main body casing 2 along the front-rear direction, and a separation roller 10 that is provided above the front end of the paper feed tray 9. And a separation pad 11 and a paper feed roller 12 provided on the rear side of the separation roller 10 (upstream in the conveyance direction of the paper 3 with respect to the separation pad 11). In addition, the feeder unit 4 includes a paper dust removing roller 13 provided on the upper front side of the separation roller 10 (downstream in the conveyance direction of the paper 3 with respect to the separation roller 10), and a pinch disposed to face the paper dust removing roller 13. And a roller 14.

Further, the paper feed side transport path of the paper 3 is folded back to the rear side in a substantially U shape from the vicinity of the paper dust removing roller 13, and further on the downstream side in the transport direction and below the process cartridge 20. Is provided with a registration roller 15 composed of a pair of rollers.
Inside the paper feed tray 9, there is provided a paper pressing plate 16 on which the paper 3 can be stacked. The paper pressing plate 16 is supported at the rear end so as to be swingable, so that the front end is disposed below, the placement position along the bottom plate of the paper feed tray 9 and the front end are disposed above, It can be swung between an inclined supply position.

  A lever 17 for lifting the front end of the paper pressing plate 16 upward is provided at the front end of the paper feed tray 9. The lever 17 is supported at a position below the front end portion of the paper pressing plate 16 so that the rear end portion is swingably supported by the lever shaft 18, and the front end portion lies on the bottom plate of the paper feed tray 9. Is swingable between the inclined posture in which the paper pressing plate 16 is lifted. When a driving force is input to the lever shaft 18, the lever 17 rotates with the lever shaft 18 as a fulcrum, the front end portion of the lever 17 lifts the front end portion of the paper pressing plate 16, and the paper pressing plate 16 is brought to the supply position. Move.

When the sheet pressing plate 16 is positioned at the supply position, the uppermost sheet 3 on the sheet pressing plate 16 is pressed by the sheet feeding roller 12, and the separation roller 10 and the separation pad 11 are rotated by the rotation of the sheet feeding roller 12. Feeding is started toward the separation position between the two.
When the paper feed tray 9 is detached from the main casing 2, the paper pressing plate 16 is positioned at the placement position. When the paper pressing plate 16 is positioned at the mounting position, the paper 3 can be stacked on the paper pressing plate 16.

  The sheet 3 fed toward the separation position by the sheet feeding roller 12 is rolled and fed one by one when it is sandwiched between the separation roller 10 and the separation pad 11 by the rotation of the separation roller 10. Is done. The fed paper 3 passes between the paper dust removing roller 13 and the pinch roller 14, and after the paper dust is removed there, the paper 3 is folded back along the U-shaped paper feeding side conveyance path, and the registration roller It is conveyed toward 15.

The registration roller 15 conveys the sheet 3 to the transfer position between the photosensitive drum 28 and the transfer roller 31 after the registration, and to transfer the toner image on the photosensitive drum 28 to the sheet.
(3) Image Forming Unit The image forming unit 5 includes a scanner unit 19, a process cartridge 20, and a fixing unit 21.

(A) Scanner Unit The scanner unit 19 is provided in the upper part of the main casing 2 and includes a laser light source (not shown), a polygon mirror 22 that is driven to rotate, an fθ lens 23, a reflecting mirror 24, a lens 25, and a reflecting mirror 26. Yes. The laser beam based on the image data emitted from the laser light source is deflected by the polygon mirror 22 and passes through the fθ lens 23 as shown by a chain line, and then the optical path is turned back by the reflecting mirror 24 and further passes through the lens 25. Thereafter, the optical path is further bent downward by the reflecting mirror 26, so that the surface of the photosensitive drum 28 of the process cartridge 20 is irradiated.

(B) Process Cartridge As shown in FIG. 2, the process cartridge 20 is provided below the scanner unit 19 in the main body casing 2 and is detachably attached to the main body casing 2 via the attachment / detachment port 6. .
The process cartridge 20 includes a drum frame 27, a photosensitive drum 28 as an image carrier, a scorotron charger 29, a developing cartridge 30, a transfer roller 31, and a cleaning unit 32 provided in the drum frame 27. Yes.

  The drum frame 27 includes a drum front opening 113 for transporting the paper 3 from outside the drum frame 27 to the transfer position, and a drum rear opening 114 for transporting the paper 3 from the transfer position to the outside of the drum frame 27. Is formed. The drum front opening 113 is disposed below the developing cartridge 30 and in front of the transfer position, and is arranged along the axial direction of the transfer roller 31 (hereinafter sometimes simply referred to as “axial direction”). It is opened so as to communicate between the inside and the outside. The drum rear opening 114 is disposed on the rear side of the transfer position so as to face the drum front opening 113 with the transfer position interposed therebetween, and communicates the inside and outside of the drum frame 27 along the axial direction. It is open.

  The photosensitive drum 28 has a cylindrical shape, and a drum body 33 formed by a positively chargeable photosensitive layer whose outermost layer is made of polycarbonate or the like, and an axial center of the drum body 33 along the axial direction of the drum body 33. And a metal drum shaft 34 that extends. The drum shaft 34 is supported by the drum frame 27, and the drum main body 33 is rotatably supported by the drum shaft 34, so that the photosensitive drum 28 is rotatable about the drum shaft 34 in the drum frame 27. Is provided. Further, the photosensitive drum 28 is rotationally driven by inputting a driving force from a motor (not shown).

  The scorotron charger 29 is supported by the drum frame 27 obliquely above the rear side of the photosensitive drum 28, and is opposed to the photosensitive drum 28 with a gap so as not to contact the photosensitive drum 28. The scorotron charger 29 is provided between the discharge wire 35 and the photosensitive drum 28, which is disposed to face the photosensitive drum 28 with a space therebetween, and the amount of discharge from the discharge wire 35 to the photosensitive drum 28. And a grid 49 for controlling. In the scorotron charger 29, a bias voltage is applied to the grid 49, and at the same time, a high voltage is applied to the discharge wire 35 to cause corona discharge of the discharge wire 35, so that the surface of the photosensitive drum 28 is uniformly positive. To charge.

The developing cartridge 30 includes a housing 36, a supply roller 37 provided in the housing 36, a developing roller 38 as a developer carrier, and a layer thickness regulating blade 39.
The developing cartridge 30 is detachably attached to the drum frame 27. Therefore, the developing cartridge 30 is attached to and detached from the process cartridge 20 through the attachment / detachment opening 6 by opening and closing the front cover 7 in a state where the process cartridge 20 is attached to the main body casing 2. Can be removed.

As will be described in detail later, the housing 36 is formed in a box shape whose rear side is opened. Inside the housing 36, a partition wall 40, a toner storage chamber 41 and a developing chamber 42 that are partitioned by the partition wall 40 are provided.
The partition wall 40 is disposed in the middle of the casing 36 in the front-rear direction, and an opening 43 is formed in the middle of the vertical direction to partition the inside of the casing 36 in the front-rear direction.

  The toner storage chamber 41 is partitioned as an internal space on the front side of the housing 36 partitioned by the partition wall 40. In the toner storage chamber 41, positively charged nonmagnetic one-component toner is stored as a developer. In the toner, a polymerizable monomer, for example, a styrene monomer such as styrene, an acrylic monomer such as acrylic acid, alkyl (C1 to C4) acrylate, alkyl (C1 to C4) methacrylate, A polymerized toner obtained by copolymerization by suspension polymerization or the like is used. This polymerized toner has a substantially spherical shape, has extremely good fluidity, and can achieve high-quality image formation.

Such a toner is blended with a colorant such as carbon black, wax, and the like, and an external additive such as silica is added to improve fluidity. The average particle size of the toner is about 6 to 10 μm.
In the toner storage chamber 41, toner detection windows 44 for detecting the remaining amount of toner are formed on both side walls 69 of the housing 36 that partitions the toner storage chamber 41. The toner detection window 44 is formed in the vicinity of the partition wall 40 so as to face both side walls 69 of the housing 36 along the width direction (the direction orthogonal to the front-rear direction and the vertical direction, the same shall apply hereinafter). Yes. Each toner detection window 44 is formed by embedding a transparent disk in the side wall 69 of the housing 36.

Further, an agitator 45 for agitating the toner is provided in the toner storage chamber 41. The agitator 45 includes an agitator rotating shaft 46 and a stirring member 47.
The agitator rotation shaft 46 is rotatably supported on both side walls 69 of the housing 36 at substantially the center of the toner storage chamber 41, and the stirring member 47 is provided on the agitator rotation shaft 46. When a driving force from a motor (not shown) is input to the agitator rotating shaft 46, the agitator rotating shaft 46 is rotated, and the agitating member 47 moves in the toner containing chamber 41 in the circumferential direction around the agitator rotating shaft 46. . Then, the toner in the toner storage chamber 41 is agitated by the agitating member 47 and discharged toward the supply roller 37 from the opening 43 communicating in the front-rear direction in the middle of the partition wall 40 in the up-down direction.

  The agitator 45 is provided with a wiper 48. The wiper 48 is attached to both ends of the agitator rotating shaft 46 in the axial direction. When the agitator rotation shaft 46 rotates, each wiper 48 moves in the toner containing chamber 41 in the circumferential direction around the agitator rotation shaft 46, and each toner detection window 44 provided on both side walls 69 of the housing 36. Wipe away. As a result, each toner detection window 44 is cleaned by the wiper 48.

The developing chamber 42 is partitioned as an internal space on the rear side of the housing 36 partitioned by the partition wall 40. In the developing chamber 42, a supply roller 37, a developing roller 38, and a layer thickness regulating blade 39 are provided.
The supply roller 37 is disposed on the rear side of the opening 43. The supply roller 37 includes a metal supply roller shaft 50 and a sponge roller 51 made of a conductive foam material that covers the supply roller shaft 50. The supply roller shaft 50 is rotatably supported on both side walls 69 of the housing 36 in the developing chamber 42. The supply roller 37 is rotationally driven when a driving force from a motor (not shown) is input to the supply roller shaft 50.

  The developing roller 38 is disposed on the rear side of the supply roller 37 in contact with the supply roller 37 so as to be compressed. The developing roller 38 includes a metallic developing roller shaft 52 and a rubber roller 53 made of a conductive rubber material that covers the developing roller shaft 52. The developing roller shaft 52 is rotatably supported on both side walls 69 of the housing 36 in the developing chamber 42. The rubber roller 53 is made of conductive urethane rubber or silicone rubber containing carbon fine particles, and the surface thereof is coated with a urethane rubber or silicone rubber coating layer containing fluorine. The developing roller 38 is rotationally driven when a driving force from a motor (not shown) is input to the developing roller shaft 52. A developing bias is applied to the developing roller 38 during development.

Further, the developing roller 38 is disposed opposite to the photosensitive drum 28 from the upper front side obliquely with the developing cartridge 30 mounted on the drum frame 27, and is located below the central portion in the vertical direction that protrudes most rearward. This part is in contact with the photosensitive drum 28.
The layer thickness regulating blade 39 includes a blade main body 54 made of a metal leaf spring material, and a pressing portion 55 having a semicircular cross section made of insulating silicone rubber provided at the free end of the blade main body 54. Yes. The layer thickness regulating blade 39 is attached to the housing 36 by fixing the base end portion of the blade body 54 to the rear end portion of the housing 36 by the attachment member 109 via the seal member 110.

The seal member 110 is disposed between the housing 36 and the attachment member 109, and prevents toner leakage from between them.
The attachment member 109 is disposed at the rear end portion of the housing 36 and includes a plate-like Freon support member 115, a plate-like back support member 111 having a substantially L-shaped cross section, and a combination screw 112. The front support member 115 is disposed on the rear side of the seal member 110. A base end portion of the blade main body 54 is disposed on the rear side of the front support member 115, and the back support member 111 is disposed on the rear side of the base end portion of the blade main body 54. The assembled screw 112 penetrates the back support member 111, the base end portion of the blade body 54, and the front support member 115 in the front-rear direction, and fixes them integrally. The layer thickness regulating blade 39 is fixed to the housing 36 by the fixing screw 130 with the mounting member 109 and the seal member 110 interposed therebetween (see FIGS. 3 and 4). Thus, the blade body 54 is attached to the housing 36 by being sandwiched between the front support member 115 and the back support member 111. The pressing portion 55 is pressed against the developing roller 38 by the elastic force of the blade body 54 at the free end portion of the blade body 54 attached as described above.

  The toner released from the opening 43 is supplied to the developing roller 38 by the rotation of the supply roller 37, and at this time, the toner is triboelectrically charged between the supply roller 37 and the developing roller 38. The toner supplied onto the developing roller 38 enters between the pressing portion 55 of the layer thickness regulating blade 39 and the rubber roller 53 of the developing roller 38 as the developing roller 38 rotates, and forms a thin layer with a constant thickness. It is carried on the developing roller 38.

  The transfer roller 31 is provided below the photosensitive drum 28 in the drum frame 27, and is opposed to and contacts the photosensitive drum 28 in the vertical direction so as to form a nip with the photosensitive drum 28. The transfer roller 31 includes a metal transfer roller shaft 56 and a rubber roller 57 made of a conductive rubber material that covers the transfer roller shaft 56. The transfer roller shaft 56 is rotatably supported by the drum frame 27. The transfer roller 31 is rotationally driven by receiving a driving force from a motor (not shown). A transfer bias is applied to the transfer roller 31 at the time of transfer.

The cleaning unit 32 is attached to the drum frame 27, and is disposed opposite the photosensitive drum 28 on the rear side of the photosensitive drum 28. The cleaning unit 32 is disposed so as to face and contact the photosensitive drum 28, and includes a cleaning brush 58 for scraping off paper dust and the like attached to the photosensitive drum 28.
As shown in FIG. 1, the surface of the photosensitive drum 28 is first charged uniformly by the scorotron charger 29 with the rotation of the photosensitive drum 28, and then the laser beam from the scanner unit 19. And an electrostatic latent image corresponding to an image to be formed on the paper 3 is formed.

  Next, when the developing roller 38 rotates, the toner carried on the developing roller 38 and charged with positive polarity is formed on the surface of the photosensitive drum 28 when it comes into contact with the photosensitive drum 28. The electrostatic latent image, that is, the surface of the photosensitive drum 28 that is uniformly charged to the positive polarity, is supplied to the exposed portion exposed to a laser beam and having a lowered potential. As a result, the electrostatic latent image on the photosensitive drum 28 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 28.

  Thereafter, the toner image carried on the surface of the photosensitive drum 28 is transferred from the outside of the drum frame 27 to the drum frame 27 through the drum front opening 113 by the sheet 3 conveyed by the registration roller 15, and the photosensitive drum 28. While passing through the transfer position between the drum 28 and the transfer roller 31, the image is transferred to the paper 3 by the transfer bias applied to the transfer roller 31. The sheet 3 onto which the toner image has been transferred is conveyed from the drum frame 27 to the outside of the drum frame 27 via the drum rear side opening 114 and is conveyed to the fixing unit 21.

Note that the transfer residual toner remaining on the photosensitive drum 28 after the transfer is collected by the developing roller 38. Further, paper dust from the paper 3 adhering to the photosensitive drum 28 after the transfer is collected by the cleaning brush 58 of the cleaning unit 32.
(C) Fixing Unit The fixing unit 21 is provided on the rear side of the process cartridge 20, and includes a fixing frame 59, and a heating roller 60 and a pressure roller 61 in the fixing frame 59.

The heating roller 60 includes a metal tube whose surface is coated with a fluororesin and a halogen lamp for heating inserted in the metal tube. The heating roller 60 is rotationally driven by inputting a driving force from a motor (not shown).
The pressure roller 61 is disposed opposite the heating roller 60 so as to press the heating roller 60. The pressure roller 61 includes a metal roller shaft and a rubber roller made of a rubber material that covers the roller shaft. The pressure roller 61 is driven according to the rotational drive of the heating roller 60.

In the fixing unit 21, the toner image transferred onto the paper 3 at the transfer position is thermally fixed while the paper 3 passes between the heating roller 60 and the pressure roller 61. The sheet 3 on which the toner image is fixed is conveyed toward a paper discharge tray 62 formed on the upper surface of the main casing 2.
The paper discharge side transport path of the sheet 3 from the fixing unit 21 to the paper discharge tray 62 is folded back to the front side in a substantially U shape from the fixing unit 21. In the discharge side transfer path, a transfer roller 63 is provided in the middle, and a discharge roller 64 is provided at the downstream end.

The sheet 3 heat-fixed in the fixing unit 21 is conveyed to the sheet discharge side conveyance path, conveyed to the sheet discharge roller 64 by the conveyance roller 63, and then discharged onto the sheet discharge tray 62 by the sheet discharge roller 64. The
2. 3 is a rear perspective view of the developing cartridge, FIG. 4 is a rear view of the developing cartridge, FIG. 5 is a side view of the developing cartridge, FIG. 6 is a bottom view of the developing cartridge, and FIG. Fig. 8 is an enlarged side cross-sectional view of the main part of the lower edge of the housing opening of the developing cartridge housing, and Fig. 8 is a rectangular shape having a simple cross section of the lower edge of the housing opening as a reference diagram. FIG. 9 and FIG. 10 are other embodiments of the lower edge of the casing opening shown in FIG. FIG.

As shown in FIGS. 2 and 3, the housing 36 of the developing cartridge 30 is formed in a box shape that integrally includes a top wall 70, a front wall 72, both side walls 69, and a bottom wall 71, with the rear side being opened. The opened portion on the rear side is formed as a housing opening 94 as an opening.
As shown in FIG. 3, the housing opening 94 is defined by the back support member 111 of the mounting member 109, the rear edge of the side walls 69 and the rear edge of the bottom wall 71, and extends in the width direction. Opened in a rectangular shape. A developing roller 38 is disposed in the housing opening 94 so as to be exposed from the housing opening 94. As shown in FIG. 5, the developing roller 38 is supported by the housing 36 so as to protrude from the inside of the housing 36 through the housing opening 94 to the outside of the housing 36 in a side view. That is, the rear end portions of the both side walls 69 of the housing 36 are provided with insertion holes 121 that face each other in the width direction. The developing roller shaft 52 is inserted into the insertion holes 121, and the rubber roller 53 is centered in the vertical direction. The developing roller 38 is rotatably supported by the housing 36 so that the portion protrudes most out of the housing 36 from the inside of the housing 36 through the housing opening 94.

As shown in FIG. 2, the upper wall 70 closes the toner storage chamber 41 and the developing chamber 42 and is formed in a flat plate shape in plan view.
The front wall 72 closes the front side of the toner storage chamber 41, has a flat plate shape when viewed from the front, and is formed to extend downward from the front end portion of the upper wall 70.
As shown in FIGS. 3 and 5, the side walls 69 are formed in a plate shape by closing the sides of the toner storage chamber 41 and the developing chamber 42. Both side walls 69 rotatably support the agitator rotating shaft 46, the supply roller shaft 50, and the developing roller shaft 52.

As shown in FIG. 2, the bottom wall 71 closes the lower part of the toner storage chamber 41 and the developing chamber 42 and integrally includes a front bottom wall 74, a central bottom wall 75, and a rear bottom wall 76.
The front bottom wall 74 is formed in a substantially semicircular cross section along the rotation locus of the agitator 45 in the toner storage chamber 41.
The central bottom wall 75 is disposed on the rear side of the front bottom wall 74 and has a substantially semicircular cross section along the supply roller 37 in the developing chamber 42.

The rear bottom wall 76 is disposed on the rear side of the central bottom wall 75 and is formed in a tongue plate shape that is inclined downward from the front side toward the rear side.
The housing 36 is provided with a gripping portion 77 that is gripped when the developing cartridge 30 and the process cartridge 20 are attached and detached. The grip portion 77 is formed so as to protrude forward from the upper portion of the front wall 68 of the housing 36.

Further, on one side wall 69 of the housing 36, as shown in FIG. 3, a gear mechanism (not shown) for rotationally driving the agitator rotating shaft 46, the supply roller shaft 50, and the developing roller shaft 52, A gear cover 79 is provided to cover the gear mechanism.
Further, in the housing opening 94 of the housing 36, it extends along the width direction of the housing 36 and is a lower edge of the housing opening 94 (that is, the rear end portion of the rear bottom wall 76). The lower edge 68 is provided with two partial rear walls 73.

Both partial rear walls 73 are disposed opposite to each other in the width direction at the lower edge portion 68 with a space therebetween, and both the rear walls 73 are arranged at both width direction end portions at the lower edge portion 68. It is provided so as to extend upward. Each partial rear wall 73 is formed in a substantially L-shaped plate in a rear view in which a portion on the inner side in the width direction is cut out.
A reinforcing portion 80 is provided at the lower edge 68 of the housing opening 94 of the housing 36.

  The reinforcing part 80 is provided between the two part rear walls 73 so as to extend along the lower edge 68 and to be fitted to the notched parts of the two part rear walls 73. The reinforcing portion 80 is formed continuously from the lower edge portion 68 of the housing opening 94, and integrally includes a reinforcing upper wall 82, a reinforcing front wall 85, a reinforcing bottom wall 83, and both reinforcing side walls 84. It is formed in a box shape with the rear side opened. More specifically, the reinforcing portion 80 is formed in a U shape (a U shape includes a substantially U shape) in which a cross section in a direction orthogonal to the width direction has an open rear side.

As shown in FIGS. 3 and 7, the reinforcing upper wall 82 is provided so as to be continuous with the lower edge portion 68 along the lower edge portion 68 and to protrude rearward.
The reinforcing front wall 85 has a substantially rectangular elongated flat plate shape extending along the lower edge portion 68 and is formed to extend downward from the front end portion of the reinforcing upper wall 82.
The reinforcing bottom wall 83 is formed in a substantially rectangular elongated flat plate shape extending along the lower edge portion 68 and is disposed so as to face the reinforcing upper wall 82 in the vertical direction. It is formed to extend toward.

As shown in FIG. 3, both the reinforcing side walls 84 have a substantially rectangular flat plate shape, and are arranged at both ends in the width direction of the reinforcing upper wall 82, the reinforcing front wall 85 and the reinforcing bottom wall 83 so as to face each other in the width direction. Has been.
Then, as shown in FIG. 7, the reinforcing portion 80 has a front end portion of the reinforcing upper wall 82 and a front end portion of the reinforcing bottom wall 83 connected to each other by the reinforcing front wall 85, thereby orthogonally crossing the width direction. The cross section is formed into a U shape with the rear side opened. Further, as shown in FIG. 3, the reinforcing portion 80 includes both reinforcing side walls 84, both ends of the reinforcing upper wall 82, both ends of the reinforcing front wall 85, and both ends of the reinforcing bottom wall 83 in the width direction. By being connected with each other, the rear side is formed in a box shape.

Further, as shown in FIG. 7, the lower edge portion 68 of the housing opening 94 is disposed at the upper portion of the reinforcing portion 80, at the rear stepped portion 97 and obliquely above the front side of the rear stepped portion 97. The cross section in the direction perpendicular to the width direction is integrally formed with the front side stepped portion 98, and is formed in a staircase shape.
The rear stepped portion 97 is formed from the rear rear surface 99 and the rear upper surface 100.
The rear side rear surface 99 is an end surface on the rear side of the reinforcing upper wall 82, and a cross section in a direction orthogonal to the width direction is formed in a flat shape that is straight in the vertical direction.

The rear upper surface 100 is provided continuously from the rear rear surface 99, and is formed in a flat plate shape whose cross section in a direction orthogonal to the width direction is bent obliquely upward from the rear rear surface 99.
The front side step portion 98 is formed by a front side rear surface 101 and a front side upper surface 102.
The front rear surface 101 is provided continuously from the front end portion of the rear upper surface 100 of the rear stepped portion 97, and a cross section in a direction orthogonal to the width direction is bent obliquely upward rearward from the front end portion of the rear upper surface 100. It is formed in a shape.

The front upper surface 102 is provided continuously from the front rear surface 101, and is formed in a flat plate shape whose cross section in a direction orthogonal to the width direction is bent obliquely upward from the upper end of the front rear surface 101.
A lower film 87 as a film member is provided on the front upper surface 102 of the lower edge portion 68.
The lower film 87 is made of a polyethylene terephthalate film or the like, has a substantially rectangular sheet shape, and its rear half is fixed to the surface of the front upper surface 102 as shown in FIGS.

More specifically, the rear end edge of the lower film 87 is disposed so as to be flush with the rear end edge of the front rear surface 101 of the lower edge 68 as shown in FIG.
That is, the lower film 87 has the rear edge of the front upper surface 102 (the ridge line between the front rear surface 101 and the front upper surface 102) as a reference in the front-rear direction, and the rear end surface of the lower film 87 is in the same position in the front-rear direction. Thus, the lower half of the lower film 87 is provided on the lower edge 68 by sticking the rear half of the lower film 87 to the front upper surface 102 via a double-sided tape (not shown).

As shown in FIG. 2, the lower film 87 has a rear half attached to the front upper surface 102, and the front half extends obliquely upward toward the front, and is formed on the lower surface of the developing roller 38. It is arranged to touch. As a result, the lower film 87 blocks the gap between the lower edge 68 and the developing roller 38, and prevents toner leakage from the gap.
The housing 36 of the developing cartridge 30 is provided with a guide portion 81 as a guide member as shown in FIGS. The guide portion 81 has a flat plate shape extending in the front-rear direction, is formed so as to protrude downward from the bottom wall 71, and a plurality of guide portions 81 are provided so as to be parallel to each other in the width direction. More specifically, as shown in FIG. 2, each guide portion 81 has a rear end portion 105 connected to the reinforcing front wall 85 and the reinforcing bottom wall 83, and a front end portion 104 connected to the front bottom wall 74. Further, each guide portion 81 includes a reinforcing bottom wall 83, a reinforcing front wall 85, a rear bottom wall 76, a central bottom wall 75, and a rear bottom wall 76 and a central bottom wall 75. It is formed integrally with the front bottom wall 74. Further, the lower end edge 106 of the guide portion 81 extends straight forward from the rear end portion of the reinforcing bottom wall 83, and gently bends obliquely upward to the front side below the central bottom wall 75. It is formed in a shape that reaches the rear end.

Further, as shown in FIG. 3, the guide portions 81 are provided with guide reinforcing portions 86 for reinforcing the guide portions 81.
As shown in FIGS. 2 and 6, the guide reinforcing portion 86 has a plate shape and stands downward from the central bottom wall 75 so as to intersect in a direction substantially orthogonal to the middle of each guide portion 81 in the front-rear direction. And is formed so as to extend in the width direction. The guide reinforcing portion 86 connects the guide portions 81 in the width direction and reinforces the guide portions 81.
3. Advantageous Effects of the Present Embodiment In this developing cartridge 30, a box-shaped reinforcing portion that extends along the lower edge 68 at the lower edge 68 of the housing opening 94 of the housing 36 and is opened at the rear side. 80 is provided. Therefore, it is possible to effectively reinforce the lower edge 68 of the housing opening 94 having low strength. Further, since the reinforcing portion 80 is formed in a box shape with the rear side opened, the thickness of the housing 36 constituting the reinforcing portion 80 and the thickness of the housing 36 constituting each portion other than the reinforcing portion 80 are uniform. Sink marks are less likely to occur during molding on the opposing surface facing the developing roller 38 that is continuous with the reinforcing portion 80, that is, on the front upper surface 102 of the lower edge portion 68. For this reason, the housing opening 94 of the housing 36 can be reliably reinforced, and the interval between the developing roller 38 and the housing opening 94 can be accurately ensured.

Further, in this developing cartridge 30, since the cross section in the direction orthogonal to the width direction of the reinforcing portion 80 is formed in a U-shape, it is easy to remove the mold at the time of molding, and a box shape can be easily formed. it can. Therefore, the housing opening 94 of the housing 36 can be reliably reinforced while facilitating molding.
In the developing cartridge 30, the reinforcing portion 80 extends along the axial direction of the developing roller 38, that is, the width direction of the housing 36 at the lower edge 68 of the housing opening 94 of the housing 36. Is arranged. Therefore, even when the vicinity of the housing opening 94 in the housing 36 is gripped, the deformation of the housing 36 can be prevented, the developing roller 38 can be damaged, or the space between the developing roller 38 and the housing 36 can be prevented. It is possible to effectively prevent toner leakage from the toner.

  In the developing cartridge 30, the lower film 87 can block the gap between the lower edge 68 of the housing opening 94 and the developing roller 38, and can prevent toner leakage from the gap. . The reinforcing portion 80 provided in the lower edge portion 68 is formed in a box shape, and the opposite surface facing the developing roller 38, that is, the front upper surface 102 of the lower edge portion 68 is formed at the time of molding. Sinking is unlikely to occur, and therefore the front upper surface 102 can be formed smoothly. As a result, the lower film 87 can be adhered to the smooth front upper surface 102, and the attachment of the lower film 87 with high accuracy can be achieved.

  If the cross section of the lower edge portion 68 is formed in a simple rectangular shape as shown in FIG. 8 as in the prior art, the lower edge portion as shown by the solid line in FIG. When the lower film 87 is pasted on the basis of the rear edge of 68, the rear edge of the lower edge 68 and the rear edge of the lower film 87 are flush with each other, and any member contacts the lower edge 68. In this case, the lower film 87 is easily peeled off from the lower edge portion 68. On the other hand, as shown by the chain line in FIG. 8, if the lower film 87 is attached to the front side of the rear end edge of the lower edge portion 68, the lower film 87 is less likely to peel from the upper surface of the lower edge portion 68. However, the standard for attaching the lower film 87 becomes unclear, and the lower film 87 cannot be reliably attached along the width direction of the lower edge portion 68. Decreases.

  However, in this developing cartridge 30, as shown in FIG. 7, the cross section of the lower edge portion 68 is formed in a stepped shape including a rear stepped portion 97 and a front stepped portion 98, and the lower film 87 is Affixed with respect to the rear end edge of the front stepped portion 98 arranged upstream of the side stepped portion 97 in the direction in which the toner leaks from the housing opening 94, that is, the front in the front-rear direction. Therefore, when any member comes into contact with the rear stepped portion 97, the lower film 87 is attached to the front stepped portion 98 disposed in front of the rear stepped portion 97, so that it is difficult to peel off from the front upper surface 102. can do. Moreover, since the lower film 87 is attached at the front side step portion 98 with reference to the rear edge of the front step portion 98, the lower film 87 can be reliably attached along the front upper surface 102. it can.

  Further, in the developing cartridge 30, the developing roller 38 protrudes from the inside of the housing 36 through the housing opening 94 to the outside of the housing 36. Therefore, in the state where the developing cartridge 30 is mounted on the drum frame 27, the developing roller 38 The roller 38 can be disposed opposite to the photosensitive drum 28 from the upper front side so that the lowermost portion other than the center portion protruding in the vertical direction comes into contact with the photosensitive drum 28. Therefore, the degree of freedom of device layout can be increased and the size of the device can be reduced. Furthermore, a space for forming the reinforcing portion 80 in the lower edge portion 68 can be secured.

  Further, in the developing cartridge 30, each guide portion 81 passes the sheet 3 conveyed from the outside of the drum frame 27 through the drum front side opening 113 into the drum frame 27 between the photosensitive drum 28 and the transfer roller 31. The guide portions 81 are provided so as to continue from the reinforcing portion 80. Therefore, the sheet 3 can be smoothly guided to the transfer position while the case opening 94 of the case 36 can be further reinforced.

Each guide portion 81 is formed along the front-rear direction orthogonal to the width direction in which the reinforcing portion 80 extends, and a plurality of guide portions 81 are provided at intervals in the width direction, so that the friction between the sheet 3 and the guide portion 81 is provided. The sheet 3 can be reliably guided to the transfer position while reducing the resistance.
Since the process cartridge 20 and the laser printer 1 include the developing cartridge 30 in which the housing opening 94 of the housing 36 is reinforced by the reinforcing portion 80, the rigidity of the process cartridge 20 and the laser printer 1 is improved. be able to.
4). In the above-described embodiment, the developing cartridge 30 is detachably attached to the drum frame 27 to form the process cartridge 20, and the process cartridge 20 is detachably attached to the main body casing 2. For example, the forming apparatus has no drum frame 27, and the main body casing 2 is provided with a photosensitive drum 28, a scorotron charger 29, a transfer roller 31, a cleaning unit 32, and the like, and the developing cartridge 30 is detachably attached to the main body casing 2. Also included are those to be attached to the.

  Further, in the above-described embodiment, the reinforcing portion 80 is formed in a U-shaped cross section in a direction orthogonal to the width direction as shown in FIG. If the cross section in the direction perpendicular to the width direction is formed in a box shape, even if it is not formed in a U shape, for example, as shown in FIG. The rear end portion of the reinforcing bottom wall 83 and the rear end portions of both reinforcing side walls 84 (not shown in FIG. 9) are connected by the reinforcing rear wall 95, whereby the inside is closed and orthogonal to the width direction. The cross section in the direction to be formed may be formed in a rectangular hollow box shape.

  Further, for example, as shown in FIG. 10, the reinforcing portion 80 is connected to the front end portion of the reinforcing upper wall 82 and the front end portion of the reinforcing bottom wall 83 so that the rear side thereof is opened and the width direction is increased. The cross section in the orthogonal direction may be formed in a V shape.

1 is a side sectional view showing an embodiment of a laser printer as an image forming apparatus of the present invention. It is a sectional side view of the process cartridge of the laser printer shown in FIG. FIG. 6 is a rear perspective view of the developing cartridge. FIG. 6 is a rear view of the developing cartridge. It is a side view of a developing cartridge. FIG. 6 is a bottom view of the developing cartridge. FIG. 6 is an enlarged side cross-sectional view of a main part of a lower edge portion of a housing opening of a developing cartridge housing. It is a principal part expanded side sectional view of the lower edge part of a housing | casing opening part when the cross section of the lower edge part of a housing | casing opening as a reference drawing is formed in the simple rectangular shape. It is a principal part expanded side sectional view of other embodiment (cross-sectional rectangular hollow box shape) of the lower edge part of the housing | casing opening part shown in FIG. It is a principal part expanded side sectional view of other embodiment (section V character shape) of the lower edge part of the housing | casing opening part shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 3 Paper 20 Process cartridge 28 Photosensitive drum 30 Developing cartridge 36 Case 38 Developing roller 68 Lower edge part 80 Reinforcement part 81 Guide part 87 Lower film 94 Case opening part 97 Front side step part 98 Back side step part

Claims (12)

A developer carrying member carrying the developer;
A housing that supports the developer carrier so that an opening is formed and is exposed from the opening;
A developing cartridge, comprising: a box-shaped reinforcing portion provided to extend along the edge of the opening and reinforcing the edge.   2. The developing cartridge according to claim 1, wherein the reinforcing portion has a U-shaped cross section in a direction orthogonal to a direction extending along an edge of the opening. The developer carrier is a developing roller;
The developing cartridge according to claim 1, wherein the reinforcing portion is disposed so as to extend along an axial direction of the developing roller.   A film member for preventing leakage of developer from the gap is provided at the edge of the opening so as to close the gap between the edge and the developer carrier. The developing cartridge according to claim 1, wherein the developing cartridge is characterized in that: The edge of the opening is formed in a step shape having a plurality of steps in a cross section in a direction orthogonal to the direction extending along the edge of the opening,
The film member is adhered to a step on the upstream side of the step on the most downstream side in the direction in which the developer leaks from the opening, with reference to the downstream edge of the step on the upstream side. The developing cartridge according to claim 4.   The said developer carrier is supported by the said housing | casing so that it may protrude outside the said housing | casing through the said opening part from the inside of the said housing | casing. Development cartridge.   The casing is provided with a guide member for guiding a recording medium onto which a developer image formed by the developer carried on the developer carrying member is transferred so as to be continuous from the reinforcing portion. The developing cartridge according to claim 1, wherein the developing cartridge is provided.   The developing cartridge according to claim 7, wherein a plurality of the guide members are provided at a distance from each other in a direction intersecting a direction in which the reinforcing portion extends. A developing cartridge according to any one of claims 1 to 8,
An image carrier that is disposed opposite to the developer carrier and carries an electrostatic latent image that is visualized as a developer image upon supply of the developer from the developer carrier. A process cartridge.   The developer carrier is disposed to face the image carrier in an oblique direction so that a portion other than the most protruding portion in the direction from the inside of the housing to the outside of the housing contacts. The process cartridge according to claim 9.   An image forming apparatus comprising the process cartridge according to claim 1 in a detachable manner. An image forming apparatus comprising the developing cartridge according to claim 1 in a detachable manner.

Images