JP2022003365A - Image forming apparatus - Google Patents

Abstract

To increase accuracy of a position of a developing roller with respect to a photoconductor drum when a drum unit and a developing unit are individually mounted on an apparatus main body.SOLUTION: A developing unit 5 includes developing unit projections 501 that project to both sides along an extension line of a rotation axis of a developing roller 51. An apparatus main body 100 has first developing projection guide parts 105 that guide the developing unit projections 501 from stating point positions in the apparatus main body 100 to relay positions closer to a photoconductor drum 41 than the starting point positions. A drum unit 4 has second developing projection guide part 405 that, continuously from the first developing projection guide parts 105, guide the developing unit projections 501 from the relay positions to end point positions closer to the photoconductor drum 41 than the relay positions.SELECTED DRAWING: Figure 10

Description

The present invention relates to an image forming apparatus including a detachable drum unit and a developing unit, respectively.

The electrophotographic image forming apparatus may include a detachable drum unit and a developing unit in the apparatus main body, respectively. The drum unit includes a photosensitive drum, and the developing unit includes a developing roller that supplies a developer to the surface of the photosensitive drum.

For example, it is known that the apparatus main body has a guide portion for guiding the drum unit and the developing unit to predetermined mounting positions (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2006-259233 Public Relations

By the way, the accuracy of the position of the developing roller with respect to the photosensitive drum greatly affects the image quality. When the drum unit and the developing unit are individually mounted on the apparatus main body, the errors in the positions of the drum unit and the developing unit in the apparatus main body are combined, and the error in the position of the developing roller with respect to the photosensitive drum becomes large. There is a risk.

An object of the present invention is to provide an image forming apparatus capable of improving the accuracy of the position of a developing roller with respect to a photosensitive drum when the drum unit and the developing unit are individually mounted on the apparatus main body.

The image forming apparatus according to one aspect of the present invention includes an apparatus main body, a drum unit, and a developing unit. The main body of the device is formed with an opening that is closed by a cover portion. The drum unit includes a rotatably supported photosensitive drum and is detachably mounted within the device body through the opening. The developing unit includes a rotatably supported developing roller and developing unit protrusions protruding to both sides along an extension of the rotation axis of the developing roller, and is detachably attached to the drum unit. The apparatus main body has a first developing projection guiding portion that guides the developing unit projection from a first starting point position in the apparatus main body to a relay position closer to the photosensitive drum than the first starting point position. The drum unit has a second developing projection guide portion that takes over the developing unit projection from the first developing projection guiding portion and guides the developing unit projection from the relay position to a first end point position closer to the photosensitive drum than the relay position.

According to the present invention, it is possible to provide an image forming apparatus capable of improving the accuracy of the position of the developing roller with respect to the photosensitive drum when the drum unit and the developing unit are individually mounted on the apparatus main body.

FIG. 1 is a cross-sectional view of an image forming apparatus according to an embodiment. FIG. 2 is a perspective view of a drum unit in the image forming apparatus according to the embodiment. FIG. 3 is a perspective view of a developing unit in the image forming apparatus according to the embodiment. FIG. 4 is a perspective view of a drum unit and a developing unit in the image forming apparatus according to the embodiment. FIG. 5 is a cross-sectional view of a drum unit in the image forming apparatus according to the embodiment. FIG. 6 is a first cross-sectional view of a drum unit and a developing unit in the image forming apparatus according to the embodiment. FIG. 7 is a second sectional view of a drum unit and a developing unit in the image forming apparatus according to the embodiment. FIG. 8 is a cross-sectional view of a portion of the image forming apparatus according to the embodiment including the drum protrusion guide portion and the developed protrusion guide portion. FIG. 9 is a perspective view of a portion of the image forming apparatus according to the embodiment including the drum protrusion guide portion and the developed protrusion guide portion. FIG. 10 is a diagram showing a terminal portion of the first developing projection guiding portion and the second developing projection guiding portion in the image forming apparatus according to the embodiment. FIG. 11 is a cross-sectional view of the urging mechanism and its peripheral portion in the image forming apparatus according to the embodiment. FIG. 12 is a side view of the drum unit and the developing unit in the image forming apparatus according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples that embody the present invention, and do not limit the technical scope of the present invention.

[Overall configuration of image forming apparatus 10]
The image forming apparatus 10 according to the embodiment executes a printing process by an electrophotographic method. The printing process is a process of forming an image on a sheet.

As shown in FIG. 1, the image forming apparatus 10 includes an apparatus main body 100 in which a main opening 102 is formed in an upper portion, and a cover portion 101 that closes the main opening 102. The cover portion 101 can open and close the main opening 102. The cover portion 101 is rotatably supported up and down by the apparatus main body 100.

The device main body 100 is a main housing including a sheet cassette 1, a sheet supply device 2, a sheet transfer device 3, a drum unit 4, a developing unit 5, a fixing device 6, and an exposure device 7.

A plurality of sheets are loaded on the sheet cassette 1. The sheet supply device 2 sends out the sheets loaded on the sheet cassette 1 one by one to the transport path 30. The sheet transfer device 3 includes a plurality of sets of transfer roller pairs 31 that transfer the sheet along the transfer path 30. The sheet transport device 3 discharges the sheet on which the image is formed from the transport path 30 to the discharge tray 101a. The discharge tray 101a is formed on the cover portion 101 (see FIG. 1).

As shown in FIGS. 5 to 7, the drum unit 4 includes a first unit housing 40, a photosensitive drum 41, a charging device 42, and a transfer roller 44. The first unit housing 40 supports the photosensitive drum 41, the charging device 42, and the transfer roller 44.

FIG. 6 is a cross-sectional view taken along the JJ plane of the drum unit 4 and the developing unit 5 shown in FIG. Further, FIG. 7 is a cross-sectional view taken along the KK plane of the drum unit 4 and the developing unit 5 shown in FIG.

The photosensitive drum 41 and the transfer roller 44 are each rotatably supported by the first unit housing 40. The photosensitive drum 41 is rotatably supported by the rotating shaft 41a, and the rotating shaft 41a is supported by the first unit housing 40.

The charging device 42 charges the surface of the photosensitive drum 41. The exposure apparatus 7 writes an electrostatic latent image on the surface of the photosensitive drum 41. The electrostatic latent image is developed into a toner image by the developing unit 5.

The transfer roller 44 transfers the toner image on the photosensitive drum 41 to the sheet. The first unit housing 40 includes a sheet introduction portion 403 that guides the sheet to a transfer position between the photosensitive drum 41 and the transfer roller 44 (see FIGS. 5 and 6).

As shown in FIGS. 6 and 7, the developing unit 5 includes a second unit housing 50 and a developing roller 51. The second unit housing 50 includes a developing container 50a for accommodating toner.

The second unit housing 50 rotatably supports the developing roller 51. Specifically, the developing roller 51 is integrally configured with the rotating shaft 51a, and the rotating shaft 51a is rotatably supported by the second unit housing 50.

The developing roller 51 supplies the toner in the developing container 50a to the surface of the photosensitive drum 41 to develop the electrostatic latent image formed on the surface of the photosensitive drum 41 into the toner image. The developing unit 5 also includes a stirring member 52 that stirs the developer in the developing container 50a.

The drum unit 4 and the developing unit 5 are individually mounted on the apparatus main body 100. In the present embodiment, the drum unit 4 is detachably mounted in the apparatus main body 100 through the main opening 102. Further, the developing unit 5 is detachably mounted in the device main body 100 through the main opening 102 in a state where the drum unit 4 is mounted in the device main body 100.

By the way, the accuracy of the position of the developing roller 51 with respect to the photosensitive drum 41 greatly affects the image quality. When the drum unit 4 and the developing unit 5 are individually mounted on the apparatus main body 100, the errors in the positions of the drum unit 4 and the developing unit 5 in the apparatus main body 100 are combined, and the error in the position of the developing roller 51 with respect to the photosensitive drum 41 becomes large. There is a risk.

On the other hand, the image forming apparatus 10 includes a structure for improving the accuracy of the mounting position of the developing roller 51 with respect to the photosensitive drum 41.

Further, the image forming apparatus 10 includes an urging mechanism 45 that elastically urges the developing unit 5 toward the photosensitive drum 41 so that the developing roller 51 is held at a position close to the photosensitive drum 41 (FIG. 7, FIG. 11). Further, the developing unit 5 includes gears 53 and 54 for transmitting a rotational force from a driving unit provided in the apparatus main body 100 to the developing roller 51 (see FIG. 12). Then, the moment M1 of the force applied to the developing unit 5 through the gears 53 and 54 may act as a force to cause a positional shift of the developing unit 5 against the urging force of the urging mechanism 45 (see FIG. 12). ). The positional deviation of the developing unit 5 has an adverse effect on the image quality.

The image forming apparatus 10 also has a structure for preventing the moment M1 of the force applied to the developing unit 5 from acting as a force that causes a positional shift of the developing unit 5 against the urging force of the urging mechanism 45. ..

Further, the photosensitive drum 41 and the developing roller 51 are arranged close to each other. Therefore, if the removal operation of the drum unit 4 and the developing unit 5 is performed in an erroneous procedure, the photosensitive drum 41 or the developing roller 51 may be damaged by coming into contact with a nearby member.

The image forming apparatus 10 also includes a structure for preventing the removal operation of the drum unit 4 and the developing unit 5 from being performed in an erroneous procedure. Hereinafter, the structures of the drum unit 4 and the developing unit 5 will be described.

The first unit housing 40 of the drum unit 4 forms a mounting space 400 in which the developing unit 5 is arranged (see FIG. 5). The developing unit 5 is detachably mounted on the first unit housing 40 of the drum unit 4 mounted on the apparatus main body 100.

That is, the developing unit 5 is attached to the apparatus main body 100 by being attached to the first unit housing 40 of the drum unit 4 attached to the apparatus main body 100. Further, after the developing unit 5 is removed from the first unit housing 40 of the drum unit 4, the drum unit 4 can be removed from the apparatus main body 100.

As shown in FIGS. 2, 4 and 12, the drum unit 4 has a first drum unit protrusion 401 protruding to both sides along an extension line of the rotation shaft 41a of the photosensitive drum 41. Further, the drum unit 4 has a second drum unit protrusion 402 projecting to both sides in parallel with the first drum unit protrusion 401.

As shown in FIGS. 1 and 8, the apparatus main body 100 has a first drum protrusion guide portion 103 and a second drum protrusion guide portion 104 provided inside a pair of side wall portions facing each other. The first drum protrusion guide portion 103 and the second drum protrusion guide portion 104 have a structure for facilitating the mounting of the drum unit 4.

The first drum protrusion guide portion 103 is a guide rail that guides the first drum unit protrusion 401 from the first drum introduction position P11 in the apparatus main body 100 to the first drum mounting position P12.

The second drum protrusion guide portion 104 is a guide rail that guides the second drum unit protrusion 402 from the second drum introduction position P21 in the apparatus main body 100 to the second drum mounting position P22.

The first drum introduction position P11 and the second drum introduction position P21 are positions along the main opening 102 in the apparatus main body 100, respectively. Further, the first drum mounting position P12 is a position farther from the main opening 102 than the first drum introduction position P11. Similarly, the second drum mounting position P22 is a position farther from the main opening 102 than the second drum introduction position P21.

The state in which the first drum unit protrusion 401 is located at the first drum mounting position P12 and the second drum unit protrusion 402 is located at the second drum mounting position P22 is a state in which the drum unit 4 is correctly mounted on the apparatus main body 100. ..

As shown in FIGS. 3, 4, and 12, the second unit housing 50 of the developing unit 5 has a first developing unit protrusion 501 and a second developing unit protrusion 502. The first developing unit protrusion 501 is formed so as to project to both sides along an extension line of the rotating shaft 51a of the developing roller 51. The second developing unit protrusion 502 is formed so as to project to both sides in parallel with the first developing unit protrusion 501.

As shown in FIGS. 1 and 8, the apparatus main body 100 has a first developing projection guide portion 105 provided inside a pair of side wall portions facing each other. Further, the first unit housing 40 of the drum unit 4 has a second developing projection guide portion 405 formed on the side plates on both sides of the mounting space 400. The first developing protrusion guide portion 105 and the second developing protrusion guide portion 405 have a structure for facilitating the mounting of the developing unit 5.

As shown in FIGS. 8 and 10, the first developing projection guide portion 105 includes a guide rail 105a that guides the first developing unit projection 501 from the developing unit introduction position P31 to the relay position P32 in the apparatus main body 100. The developing unit introduction position P31 is a position along the main opening 102 in the apparatus main body 100. The relay position P32 is closer to the photosensitive drum 41 than the developing unit introduction position P31.

Further, the first developing projection guide portion 105 guides the second developing unit projection 502. The first developing projection guide portion 105 guides the first developing unit projection 501 and the second developing unit projection 502 at two locations to stabilize the posture of the developing unit 5 when it is attached or detached.

As shown in FIG. 10, the second developing protrusion guide portion 405 is arranged inside the mounting space 400 facing the downstream end portion 105b of the guide rail 105a, and guides the first developing unit protrusion 501 to the first developing protrusion guide. It is taken over from the unit 105 and guided from the relay position P32 to the development unit mounting position P33. The developing unit mounting position P33 is closer to the photosensitive drum 41 than the relay position P32.

The second developing projection guide portion 405 is formed in a concave shape in which the first developing unit projection 501 fits at the developing unit mounting position P33. The first developing unit protrusion 501 is positioned by the second developing protrusion guide portion 405.

In the present embodiment, the first development unit protrusion 501 is guided to the development unit mounting position P33 by the second development protrusion guide portion 405 of the drum unit 4. As a result, the developing roller 51 is positioned with high accuracy with respect to the photosensitive drum 41 without being affected by the error in the position of the developing unit 5 in the apparatus main body 100.

The first drum unit protrusion 401 projects to both sides of the first development unit protrusion 501 and is formed thinner than the first development unit protrusion 501. In other words, the first drum unit protrusion 401 is formed so as to project to both sides until the tip of the first development unit protrusion 501 does not reach, and the first development unit protrusion 501 is thicker than the first drum unit protrusion 401.

Further, a part of the first drum protrusion guide portion 103 forms a guide path 103a along a common path with a part of the first developing protrusion guide portion 105 (see FIGS. 8 and 9).

In the present embodiment, a part of the first drum protrusion guide portion 103 including the first drum introduction position P11 is formed along a common path with a part of the first development protrusion guide portion 105 including the development unit introduction position P31. Has been done.

Then, the first drum protrusion guide portion 103 forms a guide path narrower than the first developing protrusion guide portion 105 on the outside of the first developing protrusion guide portion 105 (see FIGS. 8 and 9). The outside is the side opposite to the region where the photosensitive drum 41 and the developing roller 51 are arranged in the direction along the rotating shaft 41a of the photosensitive drum 41 and the rotating shaft 51a of the developing roller 51.

In the present embodiment, the first drum protrusion guide portion 103 and the first developing protrusion guide portion 105 are each formed in a groove shape (see FIG. 9). The first drum protrusion guide portion 103 has a narrower and deeper groove shape than the first developing protrusion guide portion 105.

Therefore, the portion of the first drum protrusion guide portion 103 that shares a path with the first developing protrusion guide portion 105 is a narrow and deep groove formed inside the groove formed by the first developing protrusion guide portion 105. Yes (see Figure 9).

Further, the first unit housing 40 of the drum unit 4 has a protrusion support portion 406 that supports the second development unit protrusion 502 (see FIG. 12).

When the development unit 5 is mounted on the drum unit 4, the first development unit protrusion 501 is guided to the development unit mounting position P33 by the first drum protrusion guide portion 103 and the first development protrusion guide portion 105, and the second development is performed. The unit protrusion 502 is placed on the protrusion support portion 406. As a result, the developing unit 5 is mounted on the drum unit 4.

The photosensitive drum 41 and the developing roller 51 are arranged close to each other in the apparatus main body 100. Therefore, it may be necessary for a part of the first drum protrusion guide portion 103 and the first developing protrusion guide portion 105 to be formed along a common path. The present embodiment is also applicable to such cases.

As shown in FIGS. 7 and 11, the drum unit 4 further includes an urging mechanism 45. The urging mechanism 45 elastically urges the developing unit 5 in a predetermined urging direction D1. The urging direction D1 is the direction in which the first developing unit projection 501 is directed from the relay position P32 to the developing unit mounting position P33. That is, the urging mechanism 45 elastically urges the developing unit 5 toward the photosensitive drum 41.

The developing unit introduction position P31 is an example of the first starting point position, and the developing unit mounting position P33 is an example of the first ending point position. Further, the first drum introduction position P11 is an example of the second starting point position, and the first drum mounting position P12 is an example of the second ending point position.

As shown in FIG. 12, the developing unit 5 further includes a primary gear 53 and a secondary gear 54. A coupling 53a is formed on the side surface of the primary gear 53, and the apparatus main body 100 is provided with a drive unit that engages with the coupling 63a. The primary gear 53 is a pinion gear in which a rotational force is transmitted from the drive unit via the coupling 63a.

The secondary gear 54 is a pinion gear that is integrally configured with the rotating shaft 51a of the developing roller 51 and the rotational force is transmitted from the primary gear 53. The secondary gear 54 is rotatably supported by the second unit housing 50.

As shown in FIG. 12, in a state where the developing unit 5 is mounted on the drum unit 4, the second developing unit protrusion 502 is provided on the side opposite to the side where the first developing unit protrusion 501 exists with respect to the secondary gear 54. Has been done.

When the primary gear 53 is rotationally driven, a force moment M1 is applied from the primary gear 53 to the developing unit 5 through the secondary gear 54 (see FIG. 12).

The second developing projection guide portion 405 has a first support surface 405a that supports the first developing unit projection 501 against the force moment M1 (see FIGS. 5, 10 and 12). The first support surface 405a is a surface parallel to the urging direction D1 of the urging mechanism 45.

Further, the protrusion support portion 406 has a second support surface 406a that supports the second development unit protrusion 502 against the force moment M1 (see FIG. 12). The second support surface 406a is also a surface parallel to the urging direction D1 like the first support surface 405a.

Since the first support surface 405a and the second support surface 406a are planes parallel to the urging direction D1, the force moment M1 is orthogonal to the urging direction D1 with respect to the first support surface 405a and the second support surface 406a. Act in the direction.

Therefore, it is avoided that the force moment M1 acts as a force that causes the position shift of the developing unit 5 against the urging force of the urging mechanism 45. As a result, the developing roller 51 is held with high positional accuracy with respect to the photosensitive drum 41.

As shown in FIGS. 2 and 5, the first unit housing 40 of the drum unit 4 has a first handle portion 404. When the drum unit 4 is attached to the device main body 100 or when the drum unit 4 is removed from the device main body 100, the first handle portion 404 is gripped by an operator's hand.

The first handle portion 404 can be gripped by a hand accessed through the mounting space 400. In other words, if the mounting space 400 is blocked, the first handle portion 404 cannot be gripped.

As shown in FIGS. 3 and 4, the second unit housing 50 of the developing unit 5 has a second handle portion 503. When the developing unit 5 is mounted on the drum unit 4 or when the developing unit 5 is removed from the drum unit 4, the second handle portion 503 is gripped by the operator's hand.

As shown in FIGS. 4 and 6, the developing unit 5 is mounted on the drum unit 4 to block the access path of the hand to the first handle portion 404 through the mounting space 400. Therefore, it is possible to avoid an erroneous operation of lifting the drum unit 4 before the developing unit 5 is removed from the drum unit 4.

The structure of the first handle portion 404 prevents the photosensitive drum 41 or the developing roller 51 from being damaged due to the drum unit 4 being lifted before the developing roller 51 is separated from the photosensitive drum 41.

As shown in FIG. 11, the urging mechanism 45 includes a contact member 451 and a spring 452. The abutting member 451 is displaceably supported between a predetermined reference position and an action position farther from the photosensitive drum 41 than the reference position.

In FIG. 11, the contact member 451 located at the reference position is shown by a virtual line (dashed-dotted line), and the contact member 451 located at the action position is shown by a solid line. The direction in which the contact member 451 is directed from the action position to the reference position is the urging direction D1.

The contact member 451 is displaced from the reference position to the action position by abutting on the developing unit 5 mounted on the drum unit 4.

The spring 452 elastically biases the abutting member 451 toward the photosensitive drum 41. As a result, the spring 452 urges the developing unit 5 toward the photosensitive drum 41 through the contact member 451. The spring 452 is an example of an elastic member. It is also conceivable that rubber is used instead of the spring 452.

On the other hand, the apparatus main body 100 includes a locking portion 106 capable of locking the locked portion 451a of the contact member 451. The locking portion 106 locks the contact member 451 existing at the action position to limit the movement of the drum unit 4 in the removal direction from the device main body 100.

When the contact member 451 is displaced from the action position to the reference position by the urging force of the spring 452, the contact member 451 is released from being locked by the locking portion 106.

The structure in which the locking portion 106 locks the abutting member 451 prevents the photosensitive drum 41 or the developing roller 51 from being damaged due to the drum unit 4 being lifted before the developing roller 51 is separated from the photosensitive drum 41. Prevent more reliably.

4: Drum unit 5: Developing unit 10: Image forming apparatus 40: First unit housing 41: Photosensitive drum 41a: Photosensitive drum rotating shaft 42: Charging device 44: Transfer roller 45: Energizing mechanism 50: Second unit housing 50a: Developing container 51: Developing roller 51a: Rotating shaft of developing roller 52: Stirring member 53: Primary gear 54: Secondary gear 100: Device main body 101: Cover portion 102: Main opening 103: First drum protrusion guide portion 104: 2nd drum protrusion guide part 105: 1st developing protrusion guide part 106: Locking part 400: Mounting space 401: 1st drum unit protrusion 402: 2nd drum unit protrusion 403: Sheet introduction part 404: 1st handle part 405: 2nd Developing projection guide portion 405a: First support surface 406: Projection support portion 406a: Second support surface 451: Contact member 451a: Locked portion 452: Spring 501: First development unit projection 502: Second development unit projection 503 : 2nd handle

Claims (3)

The main body of the device, which has an opening that is closed by the cover,
A drum unit that includes a rotatably supported photosensitive drum and is detachably mounted within the device body through the opening.
It comprises a rotatably supported developing roller and a developing unit that includes development unit projections protruding to both sides along an extension of the axis of rotation of the developing roller and is detachably mounted on the drum unit.
The apparatus main body has a first developing projection guiding portion that guides the developing unit projection from a first starting point position in the apparatus main body to a relay position closer to the photosensitive drum than the first starting point position.
The drum unit has a second developing projection guide portion that takes over the developing unit projection from the first developing projection guiding portion and guides the developing unit projection from the relay position to a first end point position closer to the photosensitive drum than the relay position. Forming device. The image forming apparatus according to claim 1, wherein the drum unit further includes an urging mechanism in which the development unit projection elastically urges the development unit in a direction from the relay position toward the first end point position. The drum unit further has drum unit protrusions protruding to both sides along an extension of the rotation axis of the photosensitive drum.
The device main body has a drum protrusion guide portion that guides the drum unit protrusion from a second start point position in the device main body to a second end point position farther from the opening than the second start point position.
The drum unit protrusions project to both sides of the developing unit protrusions and are formed thinner than the developing unit protrusions.
A part of the drum protrusion guide portion is narrower than the first developed protrusion guide portion on the outside of the first developed protrusion guide portion along a common path with a part of the first developed protrusion guide portion. The image forming apparatus according to claim 1 or 2, which forms a guide path.

Images