JP4770842B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus in which a developing device in which a supply roller is rotatably supported is detachably provided.

  Conventionally, there is known an image forming apparatus in which a developing device in which a supply roller for supplying a developer is rotatably supported is detachably provided (Patent Document 1). The developing device used in the image forming apparatus of Patent Document 1 is provided with a developer storage chamber integrally, and after the developer in the developer storage chamber is supplied to the supply roller, the developer is supplied from the supply roller to the development roller. Is to be supplied.

  When the amount of developer in the developing device decreases due to the image forming operation, the developing device is removed from the image forming device main body, and a new developer is supplied.

JP 2000-025310 A

  By the way, the developer deteriorates due to friction between the developers and other members, and when the developing device is used for a long time, the charging characteristics of the developer gradually deteriorate. When a new developer is supplied to the developing device with the old deteriorated developer remaining, charges move between the old developer and the new developer, and the developer tends to aggregate. When the agglomerated developer is generated in the vicinity of the supply roller in this way, there is a problem that the agglomerated developer is supplied to the developing roller during image formation after the developer is replenished, and the image quality is deteriorated.

  Accordingly, an object of the present invention is to reduce the developer around the supply roller when replenishing the developer, thereby improving the image quality.

  In order to achieve the above-described object, the present invention provides an image forming apparatus in which a developing device in which a supply roller is rotatably supported is detachably provided, a supply roller gear that rotates integrally with the supply roller, and a rotation An input gear to which driving force is input, an intermediate gear including at least one gear provided so as to be able to transmit power between the input gear and the supply roller gear, and attachment / detachment of the developing device A rack gear that is provided along a path and meshes with the supply roller gear when the developing device is attached or detached, and the supply roller gear is separated from the input gear by meshing between the supply roller gear and the rack gear when the developing device is detached. And the power transmission path via the intermediate gear from the input gear to the supply roller gear is cut off. Characterized in that it is configured urchin.

  According to such an image forming apparatus, when the developing device is detached from the image forming apparatus main body, the power transmission path from the input gear to the supply roller gear is cut. Then, the supply roller gear meshes with the rack gear along the attachment / detachment path, and rotates by the pulling force at the time of separation. At this time, since the power transmission path from the input gear to the supply roller gear is cut, the supply roller rotates smoothly without being affected by the resistance of the input gear.

  When the supply roller rotates in the direction opposite to the rotation by the power from the input gear, the developer attached to the surface of the supply roller is blown, and further, the developer around the supply roller is blown and supplied. Less developer around the roller. Therefore, when the developer is replenished thereafter, a new developer can be supplied around the supply roller, and the aggregation of the developer can be suppressed to improve the image quality.

  According to the image forming apparatus of the present invention, when the developing device is detached from the apparatus main body, the supply roller is reversed by the pulling force to be removed, so that the amount of developer around the supply roller is reduced, and development after replenishment of the developer is performed. Aggregation of the agent can be suppressed and image quality can be improved.

[First Embodiment]
<Overall configuration of image forming apparatus>
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
FIG. 1 is a side sectional view of the image forming apparatus according to the first embodiment of the present invention.

As shown in FIG. 1, the laser printer 1 includes a paper feed unit 4 for feeding paper P into a main body casing 2 as an example of an apparatus main body, and an image for forming an image on the fed paper P. An image forming unit 5 is provided.
A front cover 2A that can be opened and closed is provided on the front side of the main casing 2 (in the following description, the right in FIG. 1 is the front and the left is the rear), and the opening that is formed when the front cover 2A is opened. Thus, a developing cartridge 30 as an example of a developing device to be described later is detachable.

<Configuration of paper feed unit>
The paper feed unit 4 includes a paper feed tray 11 that is detachably attached to the bottom of the main body casing 2 and a paper pressing plate 12 provided in the paper feed tray 11. The paper feed unit 4 includes a paper feed roller 13 and a paper feed pad 14 provided above the front end of the paper feed tray 11, paper dust removing rollers 15 and 16 downstream of the paper feed roller 13, and paper And a registration roller 17 provided on the downstream side of the dust removing roller 15.

  In the paper feed unit 4 configured as described above, the paper P in the paper feed tray 11 is brought close to the paper feed roller 13 by the paper pressing plate 12 and sent out by the paper feed roller 13 and the paper feed pad 14. Then, after passing through the paper dust removing rollers 15 and 16 and the registration roller 17, they are conveyed to the image forming unit 5 one by one.

<Configuration of image forming unit>
The image forming unit 5 includes a scanner unit 20, a developing cartridge 30, a photoconductor cartridge 40, and a fixing device 50.

<Configuration of scanner unit>
The scanner unit 20 is provided in the upper part of the main casing 2 and includes a laser light emitting unit (not shown), a polygon mirror 21 that is driven to rotate, lenses 22 and 23, reflecting mirrors 24, 25, and 26. . The laser beam based on the image data emitted from the laser light emitting section passes or reflects in the order of the polygon mirror 21, the lens 22, the reflecting mirrors 24 and 25, the lens 23, and the reflecting mirror 26, as indicated by the chain line, and the photosensitive member. Irradiation is performed while scanning the surface of the photosensitive drum 41 of the cartridge 40 at a high speed.

<Configuration of developer cartridge>
The developing cartridge 30 is configured to be detachable from the photoconductor cartridge 40 and is configured to be detachable from the main body casing 2. The developing cartridge 30 includes a hollow developing frame 30A constituting an outer frame, a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, and an agitator 34.

The developing frame 30 </ b> A is divided into a toner storage chamber 37 and a developing chamber 38 in which the supply roller 33 is disposed by a partition wall 39 rising from the bottom wall in front of the supply roller 33. In the toner storage chamber 37, a toner T as an example of a developer and an agitator 34 are arranged. The developing chamber 38 is provided with a lid 36 that can be opened and closed at the top, and the toner T can be supplied to the developing chamber 38 by opening the lid 36.
The developing roller 31, the supply roller 33, and the agitator 34 are rotatably supported by a hollow developing frame 30 </ b> A that forms an outer frame of the developing cartridge 30.

  Due to the rotation of the agitator 34, the toner T in the toner storage chamber 37 is supplied to the supply roller 33 in the developing chamber 38. The toner T is supplied to the developing roller 31 by the rotation of the supply roller 33 in the direction of the arrow (counterclockwise). At this time, the toner T is positively charged by the friction between the supply roller 33 and the developing roller 31. . The toner T supplied onto the developing roller 31 enters between the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates in the arrow direction (counterclockwise direction), and has a constant thickness. Is carried on the developing roller 31 as a thin layer.

<Configuration of photoconductor cartridge>
The photoconductor cartridge 40 is mainly provided with a photoconductor frame 40A constituting an outer frame, a photoconductor drum 41, a scorotron charger 42, and a transfer roller 43. The photoconductive drum 41 is supported by the photoconductive frame 40A so as to be rotatable in the arrow direction (clockwise). The photosensitive drum 41 has a drum main body grounded and a surface portion formed of a positively chargeable photosensitive layer.

  The scorotron charger 42 is disposed above the photosensitive drum 41 so as to face the photosensitive drum 41 with a predetermined interval therebetween. The scorotron charger 42 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 41 to a positive polarity. ing.

  The transfer roller 43 is disposed below and in contact with the photosensitive drum 41 below the photosensitive drum 41, and is supported by the photosensitive frame 40A so as to be rotatable in the arrow direction (counterclockwise). The transfer roller 43 is configured by covering a metal roller shaft with a conductive rubber material. A transfer bias is applied to the transfer roller 43 by constant current control during transfer.

  The surface of the photosensitive drum 41 is uniformly positively charged by the scorotron charger 42 and then exposed by high-speed scanning of the laser beam from the scanner unit 20. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed. Here, the “electrostatic latent image” refers to an exposed portion of the surface of the photosensitive drum 41 that is uniformly positively charged and exposed to a laser beam to have its potential lowered. Next, when the toner T carried on the developing roller 31 comes into contact with the photosensitive drum 41 by the rotation of the developing roller 31, an electrostatic latent image formed on the surface of the photosensitive drum 41 is formed. Supplied. The toner T is selectively carried on the surface of the photosensitive drum 41 to be visualized, whereby a toner image is formed by reversal development.

  Thereafter, the photosensitive drum 41 and the transfer roller 43 are rotationally driven so as to sandwich and convey the paper P between them, and the paper P is conveyed between the photosensitive drum 41 and the transfer roller 43. The toner image carried on the surface of the photosensitive drum 41 is transferred onto the paper P.

<Configuration of fixing device>
The fixing device 50 is disposed on the downstream side of the photosensitive cartridge 40, and is provided with a heating roller 51, a pressure roller 52 that is disposed to face the heating roller 51 and sandwiches the paper P between the heating roller 51, and these heating rollers. 51 and a pair of transport rollers 53 provided on the downstream side of the pressure roller 52. In the fixing device 50 configured as described above, the toner T transferred onto the paper P is thermally fixed while the paper P passes between the heating roller 51 and the pressure roller 52, and then The paper P is transported to the paper discharge path 54 by the transport roller 53. The paper P sent to the paper discharge path 54 is discharged onto a paper discharge tray 56 by a paper discharge roller 55.

<Gear configuration of developer cartridge>
Next, the gear structure of the developing cartridge 30 of the present invention will be described. 2 is a cross-sectional view of a laser printer showing a state in which the developing cartridge is removed from the main body casing, FIG. 3 is an enlarged view of the developing cartridge in FIG. 2, and FIG. FIG. 4B is a perspective view of the gear cover of the developing cartridge as viewed from the inside, and FIG. 4B is a perspective view showing a side surface of the developing cartridge with the gear cover removed. In FIG. 2, the developing cartridge shows a side surface with the gear cover 80 removed.

As shown in FIG. 2, the main body casing 2 is provided with a stopper 61 and a rack gear 62. The stopper 61 and the rack gear 62 are disposed on the front side of the sheet of FIG. 2 (specifically, the inner surface of the left side wall of the main body casing 2).
The stopper 61 is a portion with which a spring receiver 78 of a second intermediate gear 76 described later comes into contact.
The rack gear 62 is a member that is provided along the attachment / detachment path of the developing cartridge 30 and rotates the supply roller gear 73 by meshing with a supply roller gear 73 described later when the development cartridge 30 is attached / detached. The rack gear 62 is continuously provided with rack teeth on the upper side.

  On the other hand, the developing cartridge 30 has an input gear 71, a developing roller gear 72, a supply roller gear 73, an agitator gear 74, a first intermediate gear 75, a second intermediate gear 76, and a third intermediate gear 77 on the left side surface shown in FIG. It has. In FIG. 2 and other drawings, tooth shapes other than the supply roller gear 73 are omitted.

  The input gear 71 is a gear to which a rotational driving force is input by meshing with a gear of a driving source such as a motor (not shown), and is rotatably supported by the developing frame 30A. The input gear 71 is driven by a gear included in a driving source during image formation, and rotates clockwise in FIG.

  The developing roller gear 72 is attached to the left end of the rotating shaft of the developing roller 31 and rotates integrally with the developing roller 31. The developing roller gear 72 is always in mesh with the input gear 71 and is driven by the input gear 71 to rotate counterclockwise in FIG. 2 during image formation.

  The supply roller gear 73 is attached to the left end portion of the rotation shaft of the supply roller 33, and rotates integrally with the supply roller 33. The supply roller gear 73 is a spur gear, and the spur gear meshes with the rack gear 62 when the developing cartridge 30 is attached to or detached from the main body casing 2.

  The supply roller gear 73 meshes with the input gear 71 via the first intermediate gear 75 and the second intermediate gear 76 during image formation. That is, the first intermediate gear 75 and the second intermediate gear 76 are gears that enable power transmission between the input gear 71 and the supply roller gear 73. In FIG. 2, since the developing cartridge 30 is detached from the main casing 2, the second intermediate gear 76 is not in mesh with the first intermediate gear 75 and the supply roller gear 73.

  The first intermediate gear 75 is rotatably supported by the developing frame 30A.

  The second intermediate gear 76 has a bearing 76A supported by a long hole 301 provided in the developing frame 30A (see FIG. 3). The elongated hole 301 extends approximately in the front-rear direction in FIG. 2, thereby allowing the bearing 76 </ b> A to move in the longitudinal direction of the elongated hole 301. The second intermediate gear 76 has a spring receiver 78 attached to the left end of the shaft 76B (see also FIG. 4B).

  The spring receiver 78 is relatively rotatable with respect to the shaft 76B and has a function as a bearing. In addition, the spring receiver 78 has a concave portion 78A opened forward in FIG.

  As shown in FIG. 4A, the gear cover 80 provided on the left side wall of the developing cartridge 30 has a spring mounting portion 81 projecting inwardly on the inner surface thereof. A coil spring 82 is attached to the spring attachment portion 81 so as to extend forward. The coil spring 82 functions as a compression spring between the spring mounting portion 81 and the concave portion 78 </ b> A of the spring receiver 78, and always urges the second intermediate gear 76 rearward via the spring receiver 78. Thus, when the developing cartridge 30 is detached from the main casing 2, the spring receiver 78 is urged rearward by the urging force of the coil spring 82, and the bearing 76 </ b> A is moved rearward in the elongated hole 301. That is, the second intermediate gear 76 moves backward. At this time, the second intermediate gear 76 is disengaged from the first intermediate gear 75 and the supply roller gear 73. On the other hand, when the developing cartridge 30 is mounted on the main casing 2, the spring receiver 78 comes into contact with the stopper 61 and the bearing 76 </ b> A is moved forward in the elongated hole 301. 75 and the supply roller gear 73.

  As described above, the supply roller gear 73 can receive power transmission from the input gear 71 only when the developing cartridge 30 is mounted on the main body casing 2, and the input gear 71 rotates clockwise in FIG. , The supply roller gear 73 is rotated counterclockwise. Further, when the supply roller gear 73 is detached from the main casing 2, the supply roller gear 73 can be engaged with the rack gear 62 on the lower side thereof. At the time of separation, the supply roller gear 73 rotates clockwise in FIG.

  The agitator gear 74 is attached to the left end of the rotating shaft of the agitator 34 and rotates integrally with the agitator 34. The agitator gear 74 meshes with the input gear 71 via the third intermediate gear 77. At the time of image formation, the agitator gear 74 is driven by the input gear 71 and rotates clockwise in FIG.

  Further, the developing cartridge 30 has a holding portion 302 disposed below the supply roller gear 73 on the left side surface shown in FIG. 2 and spaced from the supply roller gear 73 by a distance corresponding to the rack gear 62. The clamping unit 302 clamps the rack gear 62 with the supply roller gear 73 when the developer cartridge 30 is detached from the main body casing 2, and ensures the engagement between the supply roller gear 73 and the rack gear 62. 3 is formed as a guide surface 302B that is inclined with respect to the clamping surface 302A that faces the supply roller gear 73. The guide surface 302B abuts on the guide surface 62A (see FIG. 2) formed at the lower front corner of the rack gear 62 when the developing cartridge 30 is mounted on the main body casing 2, so that the developing cartridge 30 is mounted. Making it easy.

  The effects of the laser printer 1 configured as described above will be described focusing on the features of the present invention. 5A and 5B are diagrams for explaining the operation of the developing cartridge. FIG. 5A is a state in which an image is formed by being mounted on the main body casing, and FIG. 5B is a state in which the developing cartridge is removed from the main body casing. A state in the middle of pulling out, (c) shows a state after the developing cartridge is pulled out from the main body casing. In FIG. 5, for easy understanding, a stopper 61 and a rack gear 62 on the front side of the paper surface from the developing cartridge 30 (left side of the developing cartridge 30) are shown in an overlapping manner.

  As shown in FIG. 5A, the spring receiver 78 is in contact with the stopper 61 in a state where the developing cartridge 30 is mounted on the main body casing 2, and the bearing 76 </ b> A is pushed forward in the elongated hole 301. Therefore, the second intermediate gear 76 meshes with the first intermediate gear 75 and the supply roller gear 73, and the driving force input to the input gear 71 passes through the first intermediate gear 75 and the second intermediate gear 76. It is transmitted to the supply roller gear 73. Therefore, when the input gear 71 rotates clockwise in FIG. 5A, the rotation is transmitted to the first intermediate gear 75 and the second intermediate gear 76, and the supply roller gear 73 rotates counterclockwise in FIG. . Further, the developing roller gear 72 rotates counterclockwise by meshing with the input gear 71, and the agitator gear 74 rotates clockwise by the input gear 71 via the third intermediate gear 77.

  Therefore, the toner T in the toner storage chamber 37 is supplied to the developing chamber 38 by the clockwise rotation of the agitator 34. The toner T in the developing chamber 38 is drawn to the surface of the supply roller 33 and supplied to the developing roller 31.

  When the toner T is supplied to the developing roller 31, the toner T on the developing roller 31 becomes a thin layer by the layer thickness regulating blade 32 as described above, and a toner image is formed on the photosensitive drum 41 in contact with the photosensitive drum 41. Formed and used for image formation on paper P.

  Next, when the remaining amount of the toner T is reduced and the toner T is supplied to the developing cartridge 30, the developing cartridge 30 is pulled out from the main body casing 2 and separated. At this time, as shown in FIG. 5B, the spring cartridge 78 is separated from the stopper 61 by pulling the developing cartridge 30 forward. Therefore, the spring receiver 78 moves rearward by the urging force of the coil spring 82, and the second intermediate gear 76 is disengaged from both the supply roller gear 73 and the first intermediate gear 75. That is, the power transmission path between the input gear 71 and the supply roller gear 73 is disconnected. For this reason, the supply roller gear 73 can rotate relatively freely without receiving the resistance of the input gear 71.

  Then, as shown in FIG. 5B, the supply roller gear 73 meshes with the rack gear 62 while sandwiching the rack gear 62 with the sandwiching portion 302. Therefore, by the operation of pulling out the developing cartridge 30 forward, the supply roller gear 73 rotates clockwise, and the supply roller 33 also rotates clockwise. At this time, as described above, the supply roller gear 73 is free from the resistance of the input gear 71 and can be pulled out with a relatively light force.

  When the supply roller 33 rotates clockwise, that is, reversely to the time of image formation, the toner T in the developing chamber 38 is transferred from the developing chamber 38 to the toner storage chamber 37 (see FIG. 1) contrary to the time of image formation. It is skipped to. At this time, since the rotation of the supply roller gear 73 is not transmitted to the input gear 71, the agitator gear 74 does not rotate, and therefore the agitator 34 also does not rotate. Therefore, the movement of the toner T by the supply roller 33 is not obstructed by the movement of the agitator 34.

  When the developing cartridge 30 is completely pulled out from the main body casing 2 in this manner, the toner T remaining in the developing chamber 38 becomes small as shown in FIG. Therefore, when the lid 36 (see FIG. 1) is opened and the toner T is supplied to the developing chamber 38, there is little old deteriorated toner T around the supply roller 33, and aggregation is caused by mixing the new toner T and the old toner T. Is unlikely to occur. Therefore, a decrease in image quality due to aggregation of the toner T is suppressed.

  As described above in detail, according to the laser printer 1 of the present embodiment, when the developing cartridge 30 is pulled out, the supply roller 33 rotates in the reverse direction to that during image formation, and the old toner T around the supply roller 33 is recovered. Therefore, even if new toner T is supplied to the developing chamber 38, the aggregation of the toner T hardly occurs. Therefore, the image quality after replenishing the toner T can be improved as compared with the conventional case. Further, since the power transmission path between the supply roller gear 73 and the input gear 71 is disconnected when the developing cartridge 30 is pulled out, the developing cartridge 30 is removed from the main casing 2 with a relatively light force without receiving the resistance of the input gear 71. Can be pulled out.

  When the developing cartridge 30 is pulled out from the main casing 2, the rack gear 62 is held between the supply roller gear 73 and the holding portion 302, so that the rack gear 62 and the supply roller gear 73 are reliably engaged.

  Further, since the supply roller gear 73 is a spur gear, even if a large force is applied during extraction, the supply roller gear 73 is not easily damaged.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Since the second embodiment is a form in which the laser printer 1 of the first embodiment is partially changed, only the points different from the first embodiment will be described, and the same points are denoted by the same reference numerals as the first embodiment. The description is omitted. FIG. 6 is a left side view of the developing cartridge of the laser printer according to the second embodiment. In FIG. 6, the guides of the rack gear 62 and the main casing 2 are shown on the front side of the drawing.

  As shown in FIG. 6, in the developing cartridge 30 ′ of the laser printer 1 according to the second embodiment, the supply roller gear 73 ′ is composed of a first gear 73A ′ having a large pitch circle and a first gear 73A ′. The pitch circle has a second gear 73B 'having a small diameter. Both the first gear 73 </ b> A ′ and the second gear 73 </ b> B ′ are coaxially and integrally fixed to the rotation shaft of the supply roller 33. The first gear 73A ′ meshes with the second intermediate gear 76 when the developing cartridge 30 ′ is mounted, and the second gear 73B ′ meshes with the rack gear 62.

  The main casing 2 is provided with a guide rail 63 that is parallel to the rack gear 62, that is, along the attachment / detachment path of the developing cartridge 30 '. The guide rail 63 is disposed at a position near the upper surface of the developing cartridge 30 ′. A corner of the lower front end of the guide rail 63 is inclined with respect to the longitudinal direction of the guide rail 63 so as to form the guide surface 63A so that the developing cartridge 30 'can be easily mounted.

  The upper surface of the developing cartridge 30 ′ is formed in parallel with the longitudinal direction of the rack gear 62, and serves as a guide contact surface 303 that contacts the guide rail 63 when mounted on the main body casing 2. More specifically, the distance L1 from the guide contact surface 303 to the tooth tip of the second gear 73B ′ is approximately equal to the distance from the lower surface of the guide rail 63 to the tooth bottom of the rack gear 62. . Thus, when the developing cartridge 30 ′ is attached / detached, the meshing between the second gear 73 B ′ of the supply roller gear 73 ′ and the rack gear 62 can be ensured.

  According to the laser printer 1 having such a configuration, when the developing cartridge 30 ′ is pulled out from the main body casing 2 because the toner T has decreased, the second gear 73 B ′ of the supply roller gear 73 ′ is meshed. At this time, the guide abutting surface 303 slides with the guide rail 63 and the guide cartridge 63 restricts the escape of the developing cartridge 30 ′ upward, so that the engagement between the second gear 73 B ′ and the rack gear 62 is achieved. Is certain.

  As in the first embodiment, the supply roller gear 73 ′ is rotated by the drawing operation of the developing cartridge 30 ′. Since this rotation is obtained by meshing the second gear 73B ′ having a smaller pitch circle than the first gear 73A ′ used when the supply roller 33 is rotated and the rack gear 62, the rotation speed becomes high. The supply roller gear 73 ′ functions like a speed-up gear in this way, and gives a high rotational speed to the supply roller 33 when it is pulled out.

  Therefore, according to the laser printer 1 of the present embodiment, when the developing cartridge 30 ′ is detached from the main body casing 2, the supply roller 33 is rotated rapidly to sufficiently return the toner T from the developing chamber 38 to the toner containing chamber 37. The toner T around the supply roller 33 can be reduced. Therefore, the image quality can be further improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented.
For example, in the embodiment, the second intermediate gear 76 is configured to be disengaged from both the first intermediate gear 75 and the supply roller gear 73 when the developing cartridge 30 is detached, but only the engagement with the supply roller gear 73 is provided. You may comprise so that may be removed. Further, the second intermediate gear 76 is autonomously separated from the supply roller gear 73 by the rotational force obtained by the engagement of the supply roller gear 73 and the rack gear 62 by the action of the planetary gear train using the second intermediate gear 76 as a planetary gear. It can also be configured as follows.

  In the embodiment, the monochrome laser printer 1 is exemplified. However, the present invention can be applied to a color laser printer, and the present invention can be applied to a printer, a copier, a multifunction machine, and the like that perform exposure using LEDs. You can also

  In each of the above embodiments, only the developing cartridge 30 is configured to be separated from the photoconductor cartridge 40 and detachable from the main body casing 2. However, the developing cartridge 30 and the photoconductor cartridge 40 are integrated into the main body casing 2. The developing cartridge 30 and the photoreceptor cartridge 40 may not be separated from each other.

FIG. 1 is a side sectional view of the image forming apparatus according to the first embodiment of the present invention. It is sectional drawing of the laser printer which shows the state which took out the developing cartridge from the main body casing. FIG. 3 is an enlarged view of the developing cartridge in FIG. 2. (A) is the perspective view which looked at the gear cover of the developing cartridge from the inside, (b) is the perspective view which shows the side of the developing cartridge which removed the gear cover. 5A and 5B are diagrams for explaining the operation of the developing cartridge. FIG. 5A shows a state where the image forming is performed with the main body casing mounted, and FIG. 5B shows a state where the developing cartridge is being pulled out from the main body casing. The state (c) shows a state after the developing cartridge is pulled out from the main body casing. It is a left view of the developing cartridge of the laser printer concerning a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body casing 30 Developing cartridge 31 Developing roller 33 Supply roller 34 Agitator 36 Cover 37 Toner storage chamber 38 Developing chamber 40 Photoconductor cartridge 61 Stopper 62 Rack gear 63 Guide rail 71 Input gear 72 Developing roller gear 73 Supply roller gear 73A '1st Gear 73B 'second gear 74 agitator gear 75 first intermediate gear 76 second intermediate gear 76A bearing 76B shaft 77 third intermediate gear 80 gear cover 81 spring mounting portion 82 coil spring 301 elongated hole 302 clamping portion 303 guide contact surface T toner

Claims (6)

An image forming apparatus in which a developing device in which a supply roller is rotatably supported is detachably provided,
A supply roller gear that rotates integrally with the supply roller;
An input gear to which rotational driving force is input;
An intermediate gear comprising at least one or more gears provided so as to be capable of transmitting power between the input gear and the supply roller gear;
A rack gear provided along an attachment / detachment path of the developing device, and meshed with the supply roller gear when the developing device is attached / detached;
When the developing device is detached, the supply roller gear and the rack gear mesh with each other so that the supply roller gear rotates in the opposite direction to the rotation by the power from the input gear, and the intermediate gear from the input gear to the supply roller gear is rotated. An image forming apparatus configured to cut a power transmission path interposed therebetween. A spring that urges a shaft or a bearing of one of the intermediate gears in a direction in which the power transmission path is cut;
At the time of mounting the developing device, the shaft or the bearing contacts a part of the apparatus main body and moves with respect to the developing device, thereby coupling the power transmission path,
2. The structure according to claim 1 , wherein when the developing device is detached, the shaft or the bearing is moved relative to the developing device by the biasing force of the spring, and the power transmission path is disconnected. Image forming apparatus.   The developing device has a guide contact surface that contacts a part of the apparatus main body along the attachment / detachment path and secures the engagement between the supply roller gear and the rack gear when detached from the apparatus main body. The image forming apparatus according to claim 1 or 2.   4. The image forming apparatus according to claim 1, wherein the developing device includes a sandwiching portion that sandwiches the rack gear with the supply roller gear. 5.   The supply roller gear includes a first gear that meshes with the intermediate gear and a second gear that meshes with the rack gear, and a pitch circle diameter of the second gear is equal to that of the first gear. The image forming apparatus according to claim 1, wherein the image forming apparatus is smaller than a pitch circle diameter.   The image forming apparatus according to claim 1, wherein the supply roller gear includes a spur gear that meshes with the rack gear.

Images