JP2006337839A - Developing cartridge, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing cartridge that prevents deterioration of an image by preventing, by a simple configuration, charged developer from returning to a developer-accommodating chamber, and reliably controlling the charge of the developer, and to provide a process cartridge and an image forming apparatus that have the developing cartridge. <P>SOLUTION: A plate wall 49 for separating a layer thickness regulating blade 39 from a toner-accommodating chamber 41 is disposed in the developing chamber 42 of a developing-side casing 36. The free end 86 of the plate wall 49 is positioned so that a shortest distance A between the free end 86 of the plate wall 49 and the surface of the supply roller 37 is shorter than a shortest distance B between the contact part X at which the layer thickness regulating blade 39 comes into press contact the developing roller 38 and the surface of the supply roller 37. Thus, excess charged toner scraped off by the layer thickness regulating blade 39 can be prevented from returning to the toner-accommodating chamber 41. <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 image forming apparatus such as a laser printer that employs a non-magnetic one-component developing system supplies a photosensitive drum on which an electrostatic latent image is formed, and frictionally charges toner to the electrostatic latent image formed on the photosensitive drum. And a developing cartridge for developing the electrostatic latent image.
Such a developer cartridge includes a toner storage chamber for storing toner, and a development chamber for storing a supply roller, a development roller, and a layer thickness regulating blade, and the toner storage chamber and the development chamber form a communication port. What is divided by the partition wall which has been known is known (for example, refer patent document 1).

In such a developing cartridge, the toner accommodated in the toner accommodating chamber is discharged toward the developing chamber through the communication port by the agitator provided in the toner accommodating chamber, and the discharged toner is supplied. The toner is supplied to the developing roller while being frictionally charged between the roller and the developing roller. Thereafter, the toner supplied to the developing roller while being frictionally charged is carried as a thin layer on the surface of the developing roller while excess toner is scraped off by the layer thickness regulating blade.
JP 2000-275948 A

  However, in the above-described developing cartridge, of the charged toner supplied to the developing roller while being charged, surplus charged toner that is not carried as a thin layer on the surface of the developing roller is scraped off by the layer thickness regulating blade. The already charged toner that has been scraped off may stay in the developing chamber and may be returned to the toner storage chamber. In the developing cartridge, when the ratio of such charged toner to uncharged toner increases, it becomes difficult to control when the toner is frictionally charged between the supply roller and the developing roller, resulting in image deterioration. Produce. That is, it is desirable that the already charged toner once charged is subjected to development as quickly as possible.

  An object of the present invention is to prevent image deterioration by controlling the charging of a developer reliably by suppressing the return of an already charged developer to the developer storage chamber with a simple configuration. Another object is to provide a developing cartridge, and a process cartridge and an image forming apparatus including the developing cartridge.

  In order to achieve the above object, the invention described in claim 1 is a developer cartridge, comprising a developer storage chamber for storing a developer, a developer support for supporting the developer, and the developer support. A supply means for supplying the developer contained in the developer containing chamber while charging, and a layer thickness of the developer that is pressed against the developer carrier and carried on the developer carrier. An end on the side close to the supply means, provided between the layer thickness regulating means, the developer containing chamber and the layer thickness regulating means so as to partition the layer thickness regulating means from the developer containing chamber And a wall portion disposed so that a distance between the supply means and the supply portion is shorter than a distance between the pressure contact portion of the layer thickness regulating means and the developer carrier. It is characterized by having.

  According to such a configuration, the wall portion is provided between the developer containing chamber and the layer thickness regulating means so as to partition the layer thickness regulating means from the developer containing chamber. The distance between the end portion on the side close to the means and the supply means is arranged to be shorter than the distance between the pressure contact portion of the layer thickness regulating means with respect to the developer carrier and the supply means. Therefore, even if excess developer is scraped off by the layer thickness regulating means in order to regulate the layer thickness at the pressure contact portion of the layer thickness regulating means with respect to the developer carrying member, the scraped developer is It can remain between the thickness regulating means and the wall and can be carried on the developer carrier again by the pressure contact of the layer thickness regulating means. As a result, the developer scraped by the layer thickness regulating means, that is, the return of the already charged developer to the developer storage chamber can be suppressed, so that the charging of the developer can be reliably controlled. Deterioration of the image can be prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, the developer accommodating chamber, the developer carrying member, the developing unit accommodating the supply unit, and the layer thickness regulating unit, A housing is provided in which a developer storage chamber and the developing chamber are partitioned and a partition wall is formed in which a communication port is formed to communicate the chamber, and the wall portion is formed in the developing chamber. It is said.
According to such a configuration, even if the developer scraped by the layer thickness regulating means, that is, the already charged developer flows out between the layer thickness regulating means and the wall portion, the already charged Return of the developer to the developer storage chamber is suppressed. Therefore, the already charged developer can be held in the developing chamber, and the return of the already charged developer to the developer accommodating chamber can be further suppressed. As a result, the charging of the developer can be controlled more reliably, and image deterioration can be further prevented.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the wall portion includes a base end portion connected to the housing and an end portion on the side close to the supply means. In the adjacent direction between the developer accommodating chamber and the developing chamber, between the pressure contact portion of the layer thickness regulating means with respect to the developer carrying member and the end of the supply means on the developer accommodating chamber side. And a free end portion to be arranged.

  According to such a configuration, even if the developer scraped off by the layer thickness regulating means, that is, the already charged developer tries to flow out from the free end portion of the wall portion through the wall portion, The portion is disposed between the pressure contact portion of the layer thickness regulating means with respect to the developer carrier and the developer containing chamber side end of the supply means in the adjacent direction between the developer containing chamber and the developing chamber. The already-charged developer that is about to flow out again comes into contact with the supply means and is supplied to the developer carrier by the supply means. Therefore, the already-charged developer can be reliably left between the layer thickness regulating means and the wall portion, and the return of the already-charged developer to the developer storage chamber can be more reliably suppressed. .

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the developer carrying member is developed with respect to the supply unit in a direction adjacent to the developer containing chamber and the developing chamber. The layer thickness regulating means is mounted on the same side as the base end portion of the wall portion on the opposite side to the supply means on the opposite side of the agent storage chamber. Is disposed so as to be close to the wall portion, and the tip portion is provided with a pressure-contact portion that press-contacts the developer carrier, and gradually moves from the mounting portion toward the tip portion. It is characterized by extending so as to be close to the part.

  According to such a configuration, the layer thickness regulating means is extended so as to gradually approach the wall portion from the attachment portion toward the tip portion, and the pressure contact portion provided at the tip portion of the layer thickness regulating means is provided on the wall portion. It is arranged to be close. Therefore, the developer scraped by the layer thickness regulating means, that is, the already charged developer, is reliably prevented from flowing out from the free end portion of the wall portion toward the developer accommodating chamber in the pressure contact portion. be able to. Therefore, the return of the already charged developer to the developer storage chamber can be further suppressed.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the developer carrying member is configured such that the developer supplied from the supply unit moves on the supply unit side and the layer thickness regulation is performed. The means is rotated so as to reach a pressure-contact portion with respect to the developer carrier, and the supply means rotates in a direction opposite to the developer carrier at a portion facing the developer carrier. .

  According to such a configuration, the supply unit rotates in the opposite direction to the developer carrying member at the portion facing the developer carrying member, so that the developer can be reliably triboelectrically charged. Further, the developer carrying member is rotated so that the supplied developer moves on the supply means side and reaches the press contact portion, so that the developer scraped by the layer thickness regulating means, that is, the already charged The developer can be easily returned to the developer carrier again by the supply means, and the uncharged developer stored in the developer storage chamber can be easily supplied to the developer carrier. Can do.

According to a sixth aspect of the present invention, there is provided a process cartridge, wherein the developer cartridge according to any one of the first to fifth aspects and the developer from the developer carrier provided in the developer cartridge are supplied. And an image carrier that carries a developer image formed by developing the electrostatic latent image.
This process cartridge includes a developing cartridge that can control the charging of the developer by suppressing the return of the already-charged developer to the developer storage chamber. The latent image can be accurately developed to form an accurate developer image.

According to a seventh aspect of the present invention, there is provided an image forming apparatus, wherein the process cartridge according to the sixth aspect and a recording on which the developer image carried on the image carrier provided in the process cartridge is transferred. And a fixing unit for fixing the medium.
In this image forming apparatus, a high-quality image can be formed by transferring an accurate developer image onto a recording medium by an image carrier and fixing the developer image on the recording medium by a fixing unit. can do.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus, wherein the developer cartridge according to any one of the first to fifth aspects and a developer from the developer carrier provided in the developer cartridge are supplied. An image carrier that carries a developer image formed by developing the electrostatic latent image, and a fixing means for fixing the recording medium onto which the developer image carried on the image carrier is transferred It is characterized by having.

  This image forming apparatus includes a developing cartridge that can reliably control the charging of the developer by suppressing the return of the already charged developer to the developer storage chamber. The electrostatic latent image can be accurately developed to form an accurate developer image. Therefore, since the developer image can be fixed on the recording medium by the fixing unit, a high-quality image can be formed.

  The invention according to claim 9 is an image forming apparatus, wherein a developer containing chamber for containing a developer, a developer carrying member for carrying a developer, and the developer carrying member on the developer carrying member. Supply means for supplying the developer stored in the storage chamber while being charged, and layer thickness regulating means for regulating the layer thickness of the developer that is pressed against the developer carrying body and carried on the developer carrying body Between the developer containing chamber and the layer thickness regulating means so as to partition the layer thickness regulating means from the developer containing chamber, and an end near the supply means and the feeding means And the developer carrying member, such that the distance between the wall and the developer carrying member is shorter than the distance between the pressure contact portion of the layer thickness regulating unit with respect to the developer carrying member and the supply unit. From the developer and the electrostatic latent image is developed. An image bearing member for bearing a developer image that, the developer image carried on the image bearing member is characterized by comprising a fixing means for fixing the recording medium has been transferred.

  According to such a configuration, the wall portion is provided between the developer containing chamber and the layer thickness regulating means so as to partition the layer thickness regulating means from the developer containing chamber. The distance between the end close to the means and the supply means is arranged to be shorter than the distance between the pressure contact portion of the layer thickness regulating means with respect to the developer carrier and the supply means. Therefore, even if excess developer is scraped off by the layer thickness regulating means in order to regulate the layer thickness at the pressure contact portion of the layer thickness regulating means with respect to the developer carrying member, the scraped developer is It can remain between the thickness regulating means and the wall and can be carried on the developer carrier again by the pressure contact of the layer thickness regulating means. As a result, the developer scraped by the layer thickness regulating means, that is, the return of the already charged developer to the developer storage chamber can be suppressed, so that the charging of the developer can be controlled reliably. Deterioration of the image can be prevented. Then, the electrostatic latent image on the image carrier can be accurately developed to form an accurate developer image. Therefore, a high-quality image can be formed because the image carrier can transfer the developer image with high accuracy to the recording medium, and the fixing unit can fix the developer image on the recording medium. .

According to the first aspect of the present invention, the developer scraped by the layer thickness regulating means, that is, the return of the already charged developer to the developer storage chamber can be suppressed. Can be reliably controlled, and image deterioration can be prevented.
According to the second aspect of the present invention, charging of the developer can be controlled more reliably, and image deterioration can be further prevented.

According to the third aspect of the present invention, the already charged developer can be reliably left between the layer thickness regulating means and the wall portion, and the already charged developer can be returned to the developer storage chamber. Can be more reliably suppressed.
According to the fourth aspect of the present invention, the return of the already charged developer to the developer storage chamber can be further suppressed.

According to the fifth aspect of the present invention, the developer can be reliably triboelectrically charged. Further, it is possible to easily return the already-charged developer to the developer carrier again by the supply means, and the uncharged developer accommodated in the developer accommodating chamber is transferred to the developer carrier. Easy to supply.
According to the sixth aspect of the present invention, it is possible to accurately develop the electrostatic latent image on the image carrier and to form an accurate developer image.

According to the seventh aspect of the present invention, a high-quality image can be formed.
According to the eighth aspect of the present invention, it is possible to accurately develop the electrostatic latent image on the image bearing member to form an accurate developer image, and it is possible to form a high-quality image.
According to the ninth aspect of the present invention, a high-quality image can be formed.

1. 1 is a side sectional view showing an embodiment of a laser printer as an image forming apparatus of the present invention, FIG. 2 is a side sectional view of a developing cartridge of the laser printer shown in FIG. 1, and FIG. 2 is an enlarged view of a portion where the supply roller, the developing roller, the layer thickness regulating blade, and the plate wall are close to each other in the side cross section of the developing cartridge shown in FIG. 2, and FIG. 4 is a side cross section of the developing cartridge shown in FIG. FIG. FIG. 5 is a front perspective view of the developing cartridge shown in FIG. 2 in a state where the upper lid is opened.

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 after registration to a transfer position between the photosensitive drum 28 as the image carrier and the transfer roller 31 and transferring 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 as fixing means.

(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 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 cartridge 27 and a developing cartridge 30 that is detachably attached to the drum cartridge 27.

(B-1) Drum Cartridge The drum cartridge 27 includes a drum-side casing 76 and a photosensitive drum 28, a scorotron charger 29, a transfer roller 31, and a cleaning member 32 provided in the drum-side casing 76. ing.
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-side housing 76, and the drum body 33 is rotatably supported by the drum shaft 34, so that the photosensitive drum 28 is centered on the drum shaft 34 in the drum-side housing 76. It is provided to be freely rotatable. 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-side housing 76 at an obliquely upper rear side of the photosensitive drum 28, and is disposed opposite the photosensitive drum 28 so as not to contact the photosensitive drum 28. . The scorotron charger 29 is provided between the discharge wire 74 and the photosensitive drum 28, and is disposed between the discharge wire 74 and the photosensitive drum 28. The amount of charge from the discharge wire 74 to the photosensitive drum 28 is provided. And a grid 75 for controlling.

In the scorotron charger 29, a bias voltage is applied to the grid 75 and at the same time, a high voltage is applied to the discharge wire 74 to corona discharge the discharge wire 74, so that the surface of the photosensitive drum 28 is uniformly positive. To charge.
The transfer roller 31 is provided below the photosensitive drum 28 in the drum-side casing 76, is opposed to and contacts the photosensitive drum 28 in the vertical direction, and is disposed so as to form a nip with the photosensitive drum 28. Yes. 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-side housing 76. The transfer roller 31 is driven to rotate 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 member 32 is assembled to the drum-side casing 76, and is disposed opposite to the photosensitive drum 28 on the rear side of the photosensitive drum 28. The cleaning member 32 includes a cleaning brush 65 for capturing paper dust attached to the photosensitive drum 28, and a support plate that supports the cleaning brush 65 on the opposite side (rear side) of the photosensitive drum 28 with respect to the cleaning brush 65. 66.

The cleaning brush 65 is made of a nonwoven fabric in which a large number of conductive fibrous bristles are implanted, and is attached to the support plate 66 with a double-sided tape. The cleaning brush 65 is disposed so as to face and contact the photosensitive drum 28.
The support plate 66 is supported by the drum-side housing 76 while supporting the cleaning brush 65.

(B-2) Developer Cartridge As shown in FIG. 1, the developer cartridge 30 is detachably attached to the drum-side casing 76. 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 shown in FIG. 2, the developing cartridge 30 includes a developing side housing 36, a developing roller 38 as a developer carrying member, a supply roller 37 as a supply unit, a layer thickness provided in the developing side housing 36. A layer thickness regulating blade 39 as a regulating means and a plate wall 49 as a wall portion are provided.
(B-2-i) Development Side Housing As shown in FIGS. 2 and 5, the development side housing 36 includes an upper lid 70 and a housing body 87 and is formed in a box shape whose rear side is opened. A rear open portion is formed as a rear opening 94.

The rear opening 94 is defined by a back support member 111 of a mounting member 109, which will be described later, a rear end edge of both side walls 69, and a rear end edge of the bottom wall 71, and is a width direction (a direction orthogonal to the front-rear direction and the up-down direction). The same shall apply hereinafter), and is opened in a substantially rectangular shape in rear view.
The upper lid 70 closes the upper part of a toner storage chamber 41 and a development chamber 42 as a developer storage chamber, which will be described later, and is formed in a flat plate shape in plan view. The direction rib 88 and the width direction rib 89 are integrally provided.

  The front-rear direction rib 88 has a plate shape parallel to the front-rear direction with respect to the upper lid 70 in a state where the upper lid 70 is combined with the housing main body 87 (FIG. 2), and as shown in FIG. On the lower surface facing the inside of the developing-side housing 36, a plurality are arranged in parallel at intervals in the width direction. Among the plurality of front and rear direction ribs 88, the front end portions of the two front and rear direction ribs 88 that are disposed closest to the center in the width direction of the upper lid 70 are respectively provided with front protrusions 90 that are close to the front end edge of the upper lid 70. ing.

  Of the plurality of longitudinal ribs 88, the two longitudinal ribs 88 that are closest to the both end edges in the width direction of the upper lid 70 are provided with step portions 91 in the middle of the longitudinal direction, and the step portions 91 are defined as boundaries. As shown in FIG. 1, the stepped narrow shape is formed from the front side toward the rear side, and the rear protrusions 93 adjacent to the rear end edge of the upper lid 70 are provided at the respective rear end portions. Further, in the two front and rear direction ribs 88 closest to the both end edges in the width direction of the upper lid 70, the side protrusions projecting outward in the width direction are formed in the portions having a stepped narrow shape from the front side to the rear side. Each unit 100 is provided.

The width-direction rib 89 has a plate shape parallel to the width direction with respect to the upper lid 70 in a state where the upper lid 70 is combined with the housing body 87 (FIG. 2), and as shown in FIG. A plurality of the upper lids 70 are arranged in parallel on the lower surface of the upper lid 70 facing the inside of the developing side housing 36 at intervals in the front-rear direction.
The housing main body 87 is integrally provided with a front wall 72, both side walls 69, a bottom wall 71, and a blade mounting portion 73, and an upper opening 95 that covers the upper lid 70 is formed on the upper side.

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 lid 70 as shown in FIG.
Both side walls 69 close to the sides of the toner storage chamber 41 and the developing chamber 42 and are formed in a plate shape. Both side walls 69 rotatably support an agitator rotating shaft 46, a supply roller shaft 50, and a developing roller shaft 52, which will be described later.

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 77, a central bottom wall 78, and a rear bottom wall 79.
The front bottom wall 77 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 78 is disposed on the rear side of the front bottom wall 77 and has a substantially semicircular cross section along the supply roller 37 in the developing chamber 42.

The rear bottom wall 79 is disposed on the rear side of the central bottom wall 78 and is formed in a tongue plate shape that is inclined downward from the front side toward the rear side.
The blade mounting portion 73 is extended in the width direction so as to be laid between the upper rear end edges of the side walls 69, and the cross section thereof is formed in a triangular shape having a narrow width downward. The end surface is formed as an inclined surface that inclines obliquely downward and forward from the upper end to the lower end.

  The upper opening 95 is formed in a shape approximate to the outermost edge in a top view so as to be fitted to the outermost edge of the grid lattice formed by the longitudinal ribs 88 and the widthwise ribs 89 orthogonal to each other in the upper lid 70. ing. Therefore, when the upper lid 70 is assembled to the housing body 87, the fitting step portion 96, in which the step portions 91 of the two front and rear ribs 88 closest to the both end edges in the width direction of the upper lid 70 are loosely fitted, It is formed on each side wall 69 that forms the side of the upper opening 95.

  As shown in FIGS. 2 and 5, the upper lid 70 has a cross section L formed by the upper surface and the front surface of the blade mounting portion 73, with the flanges formed by the rear end edge and the two rear protrusions 93, respectively. The rear end edge of the upper lid 70 and the rear end edge of the housing main body 87 are positioned during assembly by engaging with both ends in the width direction of the character-shaped edge. Then, the upper lid 70 is rotated in the direction of the arrow (illustrated in FIG. 5) around the contact point between the collar and the edge, and the front and rear directions are orthogonal to the upper opening 95 of the housing body 87. The upper lid 70 is assembled to the housing body 87 by fitting the outermost edge of the grid lattice formed by the ribs 88 and the width direction ribs 89.

  When assembled in this manner, the rear protrusion 93 comes into contact with the blade mounting portion 73 so that the upper lid 70 and the housing main body 87 are positioned on the rear side, and at the edge of the upper lid 70 in the width direction. Positioning of the upper lid 70 and the casing main body 87 in the width direction is achieved by the side protrusions 100 respectively provided on the two adjacent longitudinal ribs 88 abutting against the inner surfaces of the side walls 69 of the casing main body 87. Further, the front protrusions 90 provided at the front end portions of the two front-rear direction ribs 88 at the center in the width direction of the upper lid 70 come into contact with the upper side of the inner surface of the front wall 72 of the housing body 87, The upper lid 70 and the housing main body 87 are positioned on the front side, and the upper lid 70 and the housing main body 87 are combined with each other without play.

The developing housing 36 is provided with a gripping portion 80 that is gripped when the developing cartridge 30 and the process cartridge 20 are attached and detached. The grip portion 80 is formed so as to protrude forward from the upper portion of the front wall 72 of the development side housing 36.
Further, on one side wall 69 of the development side housing 36, a gear mechanism portion 81 for rotationally driving the agitator rotating shaft 46, the supply roller shaft 50 and the developing roller shaft 52, and a gear cover 82 covering the gear mechanism portion 81. And are provided.

A partition 40 and a toner storage chamber 41 and a development chamber 42 partitioned by the partition 40 are provided in the development side housing 36.
The partition wall 40 is disposed in the front-rear direction of the development side housing 36 and partitions the inside of the development side housing 36 in the front-rear direction. The toner storage chamber 41 and the development chamber 42 are disposed in the middle of the partition wall 40 in the up-down direction. And a communication port 43 is formed. The lower partition 40 is formed by a connecting portion between the front bottom wall 77 and the center bottom wall 78. The upper partition wall 40 is provided in the width direction of the upper lid 70, is disposed opposite to the lower partition wall 40 with the communication port 43 in the vertical direction, and is connected to the upper lid 70 at the end (base end). Portion) substantially coincides with the step portions 91 of the two longitudinal ribs 88 that are closest to the edge in the width direction of the upper lid 70 in the front-rear direction of the upper lid 70, and along the vertical direction from the upper lid 70, It is formed so as to extend downward.

(B-2-ii) Toner Storage Chamber As shown in FIG. 2, the toner storage chamber 41 is defined as an internal space on the front side of the development side housing 36 that is 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.
Further, in the toner storage chamber 41, a toner supply port for filling toner is formed in the side wall 69 of the development side housing 36 that defines the toner storage chamber 41, and the toner supply port is the toner cap 35. Closed by.

  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 development side housing 36. 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 development side housing 36 along the width direction. Each toner detection window 44 is formed by embedding a transparent disk in the side wall 69 of the development side 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 rotating shaft 46 is rotatably supported on both side walls 69 of the developing side housing 36 at the approximate center of the toner storage chamber 41, and the stirring member 47 is provided on the agitator rotating shaft 46. A driving force from a motor (not shown) is input to the agitator rotating shaft 46, and the stirring member 47 is rotationally driven.

  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 detects each toner provided on both side walls 69 of the developing side housing 36. The window 44 is wiped off. Accordingly, each toner detection window 44 is cleaned by each wiper 48.

(B-2-iii) Developing chamber The developing chamber 42 is partitioned as an internal space on the rear side of the developing-side housing 36 that is partitioned by the partition wall 40. The developing chamber 42 includes a supply roller 37 and a developing roller. 38 and a layer thickness regulating blade 39 are accommodated, and a plate wall 49 is provided.
The supply roller 37 is disposed on the central bottom wall 78 of the developing chamber 42 on the rear side of the communication port 43, and the upper end thereof is disposed below the upper end of the lower partition wall 40. The roller 38 is disposed opposite to the front side obliquely downward.

  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, and is in contact with the developing roller 38 so as to be compressed. In this state, it is supported on both side walls 69 of the development side housing 36. That is, the side walls 69 of the development side housing 36 are provided with insertion holes 122 that face each other in the width direction, the supply roller shaft 50 is inserted through the insertion holes 122, and the supply roller 37 is connected to the development side housing. 36 is rotatably supported.

When the driving force of a motor (not shown) is input to the supply roller shaft 50, the supply roller 37 rotates counterclockwise in FIG. 2 at the contact portion with the development roller 38, that is, opposite to the rotation direction of the development roller 38. It is rotationally driven in the direction.
The developing roller 38 is disposed on the rear bottom wall 79 of the developing chamber 42 in the direction adjacent to the toner containing chamber 41 and the developing chamber 42, that is, in the front-rear direction, opposite to the toner containing chamber 41 with respect to the supply roller 37. That is, it is disposed on the rear side so as to face the supply roller 37 diagonally upward and rearward, and is in contact with the supply roller 37 so as to be compressed.

The developing roller 38 has an upper half of the upper side of the supply roller 37 disposed above the upper end.
The developing roller 38 has a larger diameter than the supply roller 37 and includes a metal developing roller shaft 52 and a rubber roller 53 made of a conductive rubber material that covers the developing roller shaft 52. Specifically, the rubber roller 53 is formed of conductive urethane rubber or silicone rubber containing carbon fine particles, and the surface thereof is covered with a coating layer of urethane rubber or silicone rubber containing fluorine. The developing roller shaft 52 is supported on both side walls 69 of the developing side housing 36 in the developing chamber 42.

The developing roller 38 is supported on both side walls 69 of the developing side housing 36 so as to protrude from the developing side housing 36 through the rear opening 94 to the outside of the developing side housing 36.
That is, the rear end portions of the both side walls 69 of the development side housing 36 are provided with insertion holes 121 facing each other in the width direction, and the developing roller shaft 52 is inserted into the insertion holes 121 so that the rubber rollers 53 The developing roller 38 is rotatably supported by the developing side housing 36 so that the central portion in the direction protrudes most out of the developing side housing 36 from the inside of the developing side housing 36 via the rear opening 94.

The developing roller 38 is driven to rotate counterclockwise in FIG. 2 when a driving force of a motor (not shown) is input to the developing roller shaft 52. A developing bias is applied to the developing roller 38 during development.
The layer thickness regulating blade 39 is provided above the developing roller 38 in the developing chamber 42 and is provided at a blade mounting portion 73 supported at the rear end sides of both side walls 69 of the housing body 87 at both ends in the width direction. It arrange | positions at the back side of the plate wall 49 mentioned later.

The layer thickness regulating blade 39 is made of metal and has a rectangular shape (see FIG. 4) in a front view, and a blade main body 54 made of a leaf spring material, and an insulative provided on a lower end portion 84 that is a tip portion of the blade main body 54. And a pressing portion 55 having a semicircular cross section made of silicone rubber.
As shown in FIG. 4, the layer thickness regulating blade 39 is provided across the width direction along the rear end surface of the blade mounting portion 73. Further, as shown in FIG. 2, the upper end portion 83 which is the attachment portion of the blade body 54 has a rear end surface of the blade attachment portion 73 whose both ends in the width direction are supported by the rear end sides of both side walls 69 of the housing body 87. In FIG. 5, the fixing member 109 is fixed via the seal member 110.

The seal member 110 is disposed between the rear end face of the blade attachment portion 73 and the attachment member 109, and prevents toner leakage from between them.
The attachment member 109 includes a plate-like front support member 115, a back support member 111 having a substantially L-shaped cross section, and an assembled screw 112. The front support member 115 is disposed on the rear side of the seal member 110. An upper end portion 83 of the blade 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 upper end portion 83 of the blade body 54. The assembled screw 112 penetrates the back support member 111, the upper end portion 83 of the blade body 54, and the front support member 115 in the front-rear direction, and integrally fixes them. The upper end portion 83 of the blade main body 54 is fixed to the blade mounting portion 73 with a fixing screw 130 so as to sandwich the seal member 110 together with the mounting member 109.

  The blade main body 54 has an upper end 83 supported by a rear end surface of the blade mounting portion 73 that is formed as an inclined surface inclined obliquely downward and forward, so that a lower end 84 as a front end is an upper end. It extends obliquely downward and forward from 83 toward the supply roller 37, and is disposed between the developing roller 38 and the plate wall 49 so as to be close to the developing roller 38 and the plate wall 49. Accordingly, the layer thickness regulating blade 39 extends obliquely downward and forward from the upper end portion 83 toward the lower end portion 84, and is extended so as to gradually approach the plate wall 49.

The pressing portion 55 is provided on the rear surface of the lower end portion 84 of the blade body 54 over the width direction. The pressing portion 55 is urged rearward by the elastic force of the blade body 54, and is slightly inclined rearward from the contact portion between the developing roller 38 and the supply roller 37 on the surface of the rubber roller 53 of the developing roller 38. It is in pressure contact.
The plate wall 49 is formed integrally with the upper lid 70 of the developing-side housing 36 in the developing chamber 42, and is disposed above the supply roller 37 between the layer thickness regulating blade 39 and the partition wall 40 in the front-rear direction. ing. As shown in FIG. 4, the plate wall 49 has a rectangular plate shape when viewed from the front, and is provided across the width direction so as to partition the layer thickness regulating blade 39 from the toner storage chamber 41 in the developing chamber 42. A base end portion 85 (upper end portion) of the plate wall 49 is connected between the upper partition 40 in the upper lid 70 of the developing side housing 36 and the blade mounting portion 73.

  The base end portion 85 of the plate wall 49 is connected to the lower surface of the upper lid 70, and the free end portion 86 (lower end portion) of the plate wall 49 extends in the vertical direction from the base end portion 85 toward the supply roller 37. More specifically, between the pressure contact portion X (see FIG. 3) of the pressing portion 55 of the layer thickness regulating blade 39 with respect to the developing roller 38 and the front end portion of the supply roller 37 in the front-rear direction, more specifically, The supply roller 37 is disposed at a position overlapping the sponge roller 51 in the vertical direction.

  Thus, the plate wall 49 extends downward along the vertical direction from the upper end to the lower end so that the free end 86 is close to the pressing portion 55 of the layer thickness regulating blade 39 and the supply roller 37. The free end portion 86 is disposed below the pressing portion 55 in the vertical direction and spaced from the supply roller 37. The layer thickness regulating blade 39 and the plate wall 49 both have an upper end 83 and a base end 85 supported by the upper lid 70, and a lower end 84 and a free end 86 extending toward the supply roller 37. The upper lid 70, the layer thickness regulating blade 39, and the plate wall 49 form a substantially triangular cross section that becomes narrower toward the lower side (supply roller 37). The lower end portion 84 of the layer thickness regulating blade 39 and the free end portion 86 of the plate wall 49 are slightly spaced from each other in the front-rear direction.

As shown in FIG. 3, the free end portion 86 of the plate wall 49 has a minimum distance A between the free end portion 86 of the plate wall 49 and the surface of the sponge roller 51 of the supply roller 37. The pressing portion 55 is disposed so as to be shorter than the shortest distance B between the pressing portion X of the pressing portion 55 against the developing roller 38 and the surface of the sponge roller 51 of the supply roller 37.
Therefore, as shown in FIG. 4, the free end portion 86 of the plate wall 49 is located below the pressure contact portion X of the pressing portion 55 of the layer thickness regulating blade 39 with respect to the developing roller 38.

(B-3) Development Transfer Operation When a driving force from a motor (not shown) is input to the agitator rotating shaft 46, the agitator rotating shaft 46 is rotated clockwise in FIG. 2, and the stirring member 47 is moved to the agitator rotating shaft. The toner storage chamber 41 is moved in the circumferential direction around 46. Then, the toner in the toner storage chamber 41 is stirred by the stirring member 47 and discharged from the communication port 43 toward the developing chamber 42.

  The toner discharged from the communication port 43 toward the developing chamber 42 is supplied to the developing roller 38 by the rotation of the supplying roller 37. At this time, the toner is supplied between the supplying roller 37 and the developing roller 38 that rotate in opposite directions. Triboelectrically charged to positive polarity. The toner supplied from the supply roller 37 moves on the side of the supply roller 37 as the development roller 38 rotates on the development roller 38, and the pressure contact portion X of the pressing portion 55 of the layer thickness regulating blade 39 with respect to the development roller 38. To reach. In the pressure contact portion X, the toner enters between the pressing portion 55 and the surface of the rubber roller 53 of the developing roller 38, and the surplus portion is scraped off by the pressing portion 55 and is regulated to a thin layer having a certain thickness. , And is carried on the surface of the rubber roller 53 of the developing roller 38.

On the other hand, as shown in FIG. 1, the surface of the photosensitive drum 28 is first uniformly charged to a positive polarity by the scorotron charger 29 as the photosensitive drum 28 rotates. Exposure is performed by high-speed scanning with a laser beam, 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 (developed), 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 to the transfer roller 31 while the sheet 3 conveyed by the registration roller 15 passes through the transfer position between the photosensitive drum 28 and the transfer roller 31. Is transferred to the sheet 3 by the transfer bias applied to the sheet 3. The sheet 3 on which the toner image is transferred is conveyed to the fixing unit 21.
The transfer residual toner remaining on the surface of the photosensitive drum 28 after the transfer is collected by the developing roller 38. Further, the paper dust from the paper 3 adhering to the surface of the photosensitive drum 28 after the transfer is removed from the surface of the photosensitive drum 28 by the cleaning brush 65 of the cleaning member 32.

(C) Fixing Unit As shown in FIG. 1, the fixing unit 21 is provided on the rear side of the process cartridge 20, and is disposed at a distance from the photosensitive drum 28 of the process cartridge 20 in the substantially front-rear direction. The fixing unit 21 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. As described above, in the developing cartridge 30, the plate wall 49 is between the layer thickness regulating blade 39 and the partition wall 40, and above the supply roller 37, the layer thickness regulating blade 39 is moved to the toner. It arrange | positions so that it may partition from the storage chamber 41. FIG. The free end portion 86 of the plate wall 49 is such that the shortest distance A between the free end portion 86 of the plate wall 49 and the surface of the sponge roller 51 of the supply roller 37 is the developing roller 38 of the pressing portion 55 of the layer thickness regulating blade 39. Is arranged so as to be shorter than the shortest distance B between the pressure contact portion X and the surface of the sponge roller 51 of the supply roller 37.

  For this reason, the contact portion is frictionally charged positively between the supply roller 37 and the developing roller 38 that rotate in opposite directions, and the development of the pressing portion 55 of the layer thickness regulating blade 39 is accompanied by the rotation of the developing roller 38. Part of the already charged toner that has reached the pressure contact portion X with respect to the roller 38 is excessively charged by the layer thickness regulating blade 39 in order to form a thin toner layer having a constant thickness in the pressure contact portion X. The scraped toner remains between the layer thickness regulating blade 39 and the plate wall 49 and is again brought into pressure contact with the layer thickness regulating blade 39 to be applied to the developing roller 38. It can be supported.

As a result, it is possible to suppress the return of the excessively charged toner scraped off by the layer thickness regulating blade 39 to the toner storage chamber 41 with a simple configuration, so that the charging of the toner can be reliably controlled. And deterioration of the image can be prevented.
Further, in the developing cartridge 30, a partition wall 40 that partitions the toner storage chamber 41 and the developing chamber 42 is disposed in the middle of the developing-side housing 36 in the front-rear direction, and a plate wall 49 is disposed in the developing chamber 42. Yes. As a result, even if surplus precharged toner scraped off by the layer thickness regulating blade 39 flows out from between the layer thickness regulating blade 39 and the plate wall 49, Return to the toner storage chamber 41 is suppressed.

Therefore, the already charged toner can be held in the developing chamber 42, and the return of the already charged toner to the toner storage chamber 41 can be further suppressed. As a result, with a simple configuration, charging of the toner can be controlled more reliably, and image deterioration can be further prevented.
Further, the base end portion 85 of the plate wall 49 is connected to the upper lid 70 of the developing side housing 36, and the free end portion 86 of the plate wall 49 is developed in the pressing portion 55 of the layer thickness regulating blade 39 in the front-rear direction. It is disposed between the pressure contact portion X with respect to the roller 38 and the front end portion of the supply roller 37.

  According to this, even if the excessively charged toner scraped off by the layer thickness regulating blade 39 tries to flow forward through the plate wall 49 from the free end portion 86 of the plate wall 49, it comes into contact with the supply roller 37 again. Then, the toner is supplied to the developing roller 38 by the supply roller 37. Therefore, with a simple configuration, the already charged toner can be reliably left between the layer thickness regulating blade 39 and the plate wall 49, and the return of the already charged toner to the toner storage chamber 41 is more reliably suppressed. can do.

  In the developing cartridge 30, the layer thickness regulating blade 39 extends from the upper end portion 83 toward the lower end portion 84 so as to gradually approach the plate wall 49, and is provided on the lower end portion 84. The portion 55 is pressed against the rubber roller 53 of the developing roller 38 by the elastic force of the blade body 54. Therefore, with a simple configuration, excessively charged toner scraped off by the pressing portion 55 of the layer thickness regulating blade 39 at the pressure contact portion X of the pressing portion 55 of the layer thickness regulating blade 39 with respect to the developing roller 38 is removed from the plate wall 49. Outflow from the free end portion 86 toward the toner storage chamber 41 can be reliably prevented. Therefore, the return of the already charged toner to the toner storage chamber 41 can be further suppressed.

  Further, in the developing side housing 36 of the developing cartridge 30, the upper lid 70 is provided with a plurality of front and rear direction ribs 88 and width direction ribs 89 so as to form a grid lattice perpendicular to each other. Front protrusions 90 adjacent to the front edge of the upper lid 70 are provided at the front ends of the two front-rear ribs 88 closest to the center in the width direction of the 70, respectively. Two adjacent front and rear direction ribs 88 are each provided with a stepped portion 91 and a side protruding portion 100, and further, a rear protruding portion 93 is provided at the rear end thereof.

  Therefore, the front protrusion 90, the side protrusion 100, and the rear protrusion 93 are in contact with the inner peripheral surface of the upper opening 95 of the housing main body 87, so that the front-rear rib 88 and the width direction The outermost edge of the grid lattice formed by the ribs 89 is fitted into the upper opening 95, the upper lid 70 can be assembled to the housing body 87 with high accuracy, and the plate wall 49 provided on the upper lid 70 is described above. It can be accurately arranged at a desired position in the development side housing 36.

  In particular, the rear protrusions 93 provided at the rear end portions of the two front-rear direction ribs 88 that are closest to the width direction edge of the upper lid 70 are the width direction both ends of the blade mounting portion 73, that is, the blade mounting portion. 73 is a position that is supported by both side walls 69 and is in contact with the central portion in the width direction at a position where rigidity is high, so that the positioning is stable and the mounting accuracy of the upper lid 70 to the housing body 87 is improved. Can be achieved.

Further, the front protrusions 90 respectively provided at the front end portions of the two front-rear direction ribs 88 that are closest to the center in the width direction of the upper lid 70 are supported by the center portion in the width direction of the front wall 72, that is, both side walls 69. Since it is in contact with the front wall 72 at a position where the rigidity is low compared to the both end portions and is easy to bend, it is possible to prevent the front wall 72 from being bent at the center in the width direction.
In addition, strict dimensional management is indispensable for each contact point between the upper lid 70 and the casing main body 87, but since it is local as described above, the labor required for management can be reduced. .

  In the developing cartridge 30, the supply roller 37 rotates in a direction opposite to the rotation direction of the developing roller 38 at the contact portion with the developing roller 38, so that the toner can be reliably frictionally charged. Further, the developing roller 38 is arranged so that the toner supplied from the supply roller 37 moves on the supply roller 37 side and reaches the pressure contact portion X of the pressing portion 55 of the layer thickness regulating blade 39 with respect to the developing roller 38. The half portion is rotated so as to move from the front side toward the rear side. Since the supply roller 37 rotates in the opposite direction at the contact portion with respect to the developing roller 38, the upper half portion moves from the front side toward the rear side in the same manner as the developing roller 38. For this reason, it is possible to easily return the excessively charged toner scraped off by the layer thickness regulating blade 39 to the developing roller 38 again by the supply roller 37, and also to the uncharged toner stored in the toner storage chamber 41. This toner can be easily supplied to the developing roller 38.

In the process cartridge 20 and the laser printer 1, as described above, the return of the excessively charged toner scraped off by the layer thickness regulating blade 39 to the toner storage chamber 41 is suppressed, and the toner is charged. Since the developing cartridge 30 capable of preventing image deterioration by being reliably controlled is provided, the electrostatic latent image on the photosensitive drum 28 can be accurately developed to form a highly accurate toner image. And high-quality image formation can be achieved.
3. In the above-described embodiment, the developing cartridge 30 is detachably attached to the drum cartridge 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 cartridge 27, and the main body casing 2 is provided with a photosensitive drum 28, a scorotron charger 29, a transfer roller 31, a cleaning member 32, and the like, and the developing cartridge 30 can be detachably attached to the main body casing 2. There is no drum cartridge 27 or developing cartridge 30, and the main body casing 2 is provided with a photosensitive drum 28, a scorotron charger 29, a transfer roller 31, a cleaning member 32, etc., and a toner storage chamber 41, a developing roller. 38 In addition, a roller provided with a supply roller 37, a layer thickness regulating blade 39, and a plate wall 49 is also included.

1 is a side sectional view showing an embodiment of a laser printer as an image forming apparatus of the present invention. FIG. 2 is a side sectional view of a developing cartridge of the laser printer shown in FIG. 1. FIG. 3 is an enlarged view of a portion where a supply roller, a developing roller, a layer thickness regulating blade, and a wall are close to each other in the side cross section of the developing cartridge shown in FIG. 2. FIG. 3 is a cross-sectional view taken along line AA in the side cross section of the developing cartridge shown in FIG. 2. FIG. 3 is a front perspective view of the developing cartridge shown in FIG. 2 with an upper lid opened.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 3 Paper 20 Process cartridge 21 Fixing part 28 Photosensitive drum 30 Developing cartridge 36 Developing side housing 37 Supply roller 38 Developing roller 39 Layer thickness control blade 40 Bulkhead 41 Toner accommodating chamber 42 Developing chamber 43 Communication port 49 Plate wall 83 Upper end 84 Lower end 85 Base end 86 Free end

Claims (9)

A developer storage chamber for storing the developer;
A developer carrying member carrying the developer;
Supplying means for charging the developer carrying member while charging the developer accommodated in the developer accommodating chamber;
A layer thickness regulating means for regulating the layer thickness of the developer that is pressed against the developer carrier and carried on the developer carrier;
Between the developer containing chamber and the layer thickness regulating means, the layer thickness regulating means is provided so as to be separated from the developer containing chamber, and an end portion on the side close to the supply means and the supply means A wall portion disposed such that a distance between the pressure-contacting portion of the layer thickness regulating means with respect to the developer carrier and the supply means is shorter than
A developing cartridge comprising: The developer accommodating chamber, the developer carrying member, the developing chamber accommodating the supply means and the layer thickness regulating means, the developer accommodating chamber and the developing chamber are partitioned, and a communication port for communicating these is provided. A housing formed with a partition wall to be formed;
The developing cartridge according to claim 1, wherein the wall portion is formed in the developing chamber. The wall is
A proximal end connected to the housing;
The end portion on the side close to the supply means, and in the adjacent direction between the developer storage chamber and the development chamber, the pressure contact portion of the layer thickness regulating means with respect to the developer carrier and the development of the supply means A free end portion disposed between the agent storage chamber side end portion, and
The developing cartridge according to claim 1, wherein the developing cartridge is provided. The developer carrier is disposed opposite to the supply unit on the opposite side of the developer storage chamber with respect to the supply unit in a direction adjacent to the developer storage chamber and the development chamber.
The layer thickness regulating means is arranged such that its mounting portion is supported by the housing on the same side as the base end portion of the wall portion, and the distal end portion thereof is close to the wall portion. A press-contact portion that press-contacts the developer carrying member is provided, and is extended from the mounting portion toward the tip portion so as to gradually approach the wall portion. 3. The developing cartridge according to 3. The developer carrier is rotated so that the developer supplied from the supply unit moves on the supply unit side and reaches a pressure contact portion of the layer thickness regulating unit with respect to the developer carrier.
The developer cartridge according to claim 4, wherein the supply unit rotates in a direction opposite to the developer carrier at a portion facing the developer carrier. A developing cartridge according to any one of claims 1 to 5;
An image carrier that carries a developer image formed by supplying a developer from the developer carrier provided in the developer cartridge and developing an electrostatic latent image;
A process cartridge comprising: A process cartridge according to claim 6;
Fixing means for fixing the recording medium on which the developer image carried on the image carrier provided in the process cartridge is transferred;
An image forming apparatus comprising: A developing cartridge according to any one of claims 1 to 5;
An image carrier that carries a developer image formed by supplying a developer from the developer carrier provided in the developer cartridge and developing an electrostatic latent image;
Fixing means for fixing the recording medium onto which the developer image carried on the image carrier is transferred;
An image forming apparatus comprising: A developer storage chamber for storing the developer;
A developer carrying member carrying the developer;
Supplying means for charging the developer carrying member while charging the developer accommodated in the developer accommodating chamber;
A layer thickness regulating means for regulating the layer thickness of the developer that is pressed against the developer carrier and carried on the developer carrier;
Between the developer containing chamber and the layer thickness regulating means, the layer thickness regulating means is provided so as to be separated from the developer containing chamber, and an end portion on the side close to the supply means and the supply means A wall portion disposed such that a distance between the supply portion and the pressure contact portion of the layer thickness regulating means against the developer carrier is shorter than
An image carrier that carries a developer image formed by supplying a developer from the developer carrier and developing an electrostatic latent image; and
Fixing means for fixing the recording medium onto which the developer image carried on the image carrier is transferred;
An image forming apparatus comprising:

Images