JP6520148B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus capable of easily separating a developing unit from an image forming apparatus main body.

  The electrophotographic image forming apparatus includes an MFP (Multi Function Peripheral), a facsimile machine, a copier, a printer, etc. having a scanner function, a facsimile function, a copying function, a function as a printer, a data communication function, and a server function. is there. In general, an image forming apparatus forms a toner image on a photosensitive member by a developing roller, transfers the toner image formed on the photosensitive member to a transfer material, and fixes the toner image on the transfer material to form an image on the transfer material. Form

  The developing device in the image forming apparatus is a portion that forms a toner image on the photosensitive member by adsorbing the toner to the electrostatic latent image on the photosensitive member. The developing device includes a stirring roller for stirring the developer, a developing roller for transporting the developer onto the latent image carrier, and a regulating member for regulating the amount of developer transported from the developing roller onto the photosensitive member. There is. The developing device and the photosensitive member are consumable parts, and are detachable from the image forming apparatus main body as an independent unit. The developing unit and the photosensitive unit are replaced independently of other parts at the end of their life.

  In the image forming apparatus, the gap between the photosensitive member and the developing device needs to be defined with high accuracy because it affects the developing electric field. Heretofore, various techniques have been proposed for fixing a developing device at a predetermined position in an image forming apparatus.

  For example, Patent Document 1 below discloses an image forming apparatus provided with a developing unit pressing slider and an operation lever for operating the developing unit pressing slider. The developing unit pressure-contacting slider can be in a pressing state where the pressure-contacting member of the developing unit is pressed against the pressure-contacting member of the photosensitive unit via a supporting member of the developing unit, and a releasing state where the pressing is released.

  Patent Document 2 below discloses an image forming apparatus provided with a pressing mechanism that presses a bottom surface of a developing unit detachably mounted on the image forming apparatus to press the developing roller of the developing unit against the photosensitive drum. . The pressing mechanism includes a pressing plate, a cam member that pushes up the pressing plate, an operating rotation shaft to which the cam member is fixed, and an operation unit that rotates the operating rotation shaft. A coil spring is mounted on the cam member, and is always urged in the direction of the standby position.

JP, 2010-224085, A JP 2005-208075 A

  In the techniques of Patent Documents 1 and 2, when the developing unit is separated from the photosensitive member for the purpose of replacing the developing unit, the operation lever is pivoted to the separated position. As a result, the pressure contact of the developing unit is released, and the developing unit moves from the pressure contact position to the separated position by its own weight.

  However, in the prior art, when attempting to separate the developing unit from the photosensitive member, the developing unit may not move to the separated position under its own weight. For example, when the rotation fulcrum position of the developing unit is almost on the center of gravity and the action by its own weight is small, or the connecting portion of the developing unit with the drive member on the main body side that drives the developing roller etc. This problem has arisen, for example.

  The present invention is for solving the above-mentioned problems, and an object thereof is to provide an image forming apparatus capable of easily separating a developing unit from a photosensitive member.

The image forming apparatus according to one aspect of the present invention is detachable from the photosensitive body supported by the image forming apparatus main body and the image forming apparatus main body, and when mounted on the image forming apparatus main body, the fulcrum shaft is centered. And the developing unit including the developing roller for applying the developer to the photosensitive member, and the image forming apparatus main body when it is rotated to a position where it contacts the developing unit; And a pressing member that applies a pressing force to the photosensitive member, and a force that separates from the photosensitive member with respect to the developing unit when it is rotated with respect to the image forming apparatus main body and rotated to a position contacting the developing unit. a spacing member for applying, an operating member for operating the respective rotation of the pressure member and the separating member, the operation extending parallel to the insertion direction of the developing unit when mounting the developing unit to the image forming apparatus main body And each of the pressure contact member, the separation member, and the operation member is attached to the operation shaft and rotates coaxially to maximize the force with which the pressure contact member is in pressure contact with the photosensitive member with respect to the developing unit. From the position of the operation member, when the operation member is rotated by a predetermined angle, the spacing member starts applying a force for separating the developing unit from the photosensitive member.

  In the above image forming apparatus, preferably, the pressure contact member is a first pressure contact member attached to the front end of the operation shaft in the insertion direction, and a second contact member attached to the back end of the operation shaft in the insertion direction. The separation member is attached to the rear end of the operation shaft in the insertion direction, and is not attached to the front end of the operation shaft in the insertion direction.

  Preferably, in the image forming apparatus, the operation member is in a first state in which the developing unit and the pressing member are in contact and the developing unit and the separating member are not in contact, and the developing unit and the pressing member are not in contact The rotation of each of the spacing member and the pressure contact member is operated between the second state in which the spacing member and the spacing member are in contact with each other.

  Preferably, the image forming apparatus further includes a main body side drive gear for transmitting a rotational force to the developing roller, and the fulcrum shaft is included in the developing unit when the developing unit is mounted on the image forming apparatus main body. Above the roller, the developing unit is connected to the main drive gear coaxially with the fulcrum shaft.

In the above image forming apparatus, preferably, the developing unit includes a developing unit main body accommodating the developing roller, a unit side projecting portion projecting from the developing unit main body, and a developing unit when mounting the developing unit to the image forming apparatus main body And a unit-side engaging portion extending from the unit-side protrusion parallel to the insertion direction of the developer unit, and the separating member is rotated to a position where it contacts the developing unit. Between the engaging portion and the unit side engaging portion, a force is applied to separate the developing unit from the photosensitive member .

  According to the present invention, it is possible to provide an image forming apparatus capable of easily separating the developing unit from the photosensitive member.

FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus 100 according to an embodiment of the present invention. FIG. 6 is a perspective view showing the configuration of a developing unit 134 according to an embodiment of the present invention. FIG. 6 is a perspective view showing a configuration of an image forming apparatus main body side supporting the developing unit 134. FIG. 7 is a perspective view showing the configuration of the developing unit 134 and the periphery thereof when the developing unit 134 is mounted on the image forming apparatus main body in an embodiment of the present invention. It is a perspective view which shows the structure of the isolation | separation lever 204 vicinity in one embodiment of this invention. FIG. 7 is a partial cross-sectional view showing the relationship between the lever unit 200 and the developing unit 134 in the embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing a change in the contact position of the developing unit 134 and the pressure contact lever 203 or the separation lever 204 when the operation lever 205 is rotated in the direction indicated by the arrow AR2 (FIG. 4). It is an enlarged view of FIG.7 (c).

  Hereinafter, an embodiment of the present invention will be described based on the drawings.

  In the present embodiment, the case where the image forming apparatus is a monochrome copying machine will be described. The image forming apparatus may be a color copier, an MFP, a facsimile machine, a printer, or the like as well as a monochrome copier.

  In the following description, the portion of the image forming apparatus 100 excluding the photosensitive drum 131 and the developing unit 134 may be referred to as “image forming apparatus main body”. Further, the front side in the insertion direction of the developing unit 134 when mounting the developing unit 134 in the image forming apparatus main body may be referred to as “front side” and the rear side as “back side”.

  FIG. 1 is a cross-sectional view showing the configuration of an image forming apparatus 100 according to an embodiment of the present invention.

  Referring to FIG. 1, image forming apparatus 100 is an image forming apparatus that forms an image by an electrophotographic method, and includes a sheet feeding unit 110, a sheet conveyance unit 120, an image forming unit 130, and a fixing unit 140. , An output tray 150, an ADF (Auto Document Feeder) unit 160, and a scanner 170.

  The sheet feeding unit 110 includes a plurality of sheet feeding cassettes for storing sheets for each size, and a sheet feeding roller for feeding sheets from any of the plurality of sheet feeding cassettes.

  The sheet conveyance unit 120 conveys a sheet along the conveyance path RT. The transport route RT extends upward from the lower direction in FIG. The sheet conveyance unit 120 includes a registration roller for feeding the sheet to the transfer roller 135 and a sheet discharge roller for discharging the sheet on which the image is formed to the sheet discharge tray 150.

  The image forming unit 130 transfers an image on a sheet by an electrophotographic method. The image forming unit 130 includes a photosensitive drum 131, a charging device 132, an exposure device 133, a developing unit 134, a transfer roller 135, and a cleaner 136.

  The charging device 132 charges the photosensitive drum 131. The exposure device 133 forms a latent image on the photosensitive drum 131 uniformly charged by the charging device 132 based on the image data. The developing unit 134 is configured by the developing roller 302, the stirring roller 310, and the like. The developing unit 134 forms (develops) a toner image by causing the developing roller 302 to attach toner on the photosensitive drum 131 on which the latent image is formed. The stirring roller 310 stirs the developer and supplies it to the developing roller 302. The transfer roller 135 transfers the toner image formed on the photosensitive drum 131 onto a sheet. A high voltage is applied to the transfer roller 135. The cleaner 136 removes the charge and toner remaining on the photosensitive drum 131 after development.

  The photosensitive unit 137 includes a photosensitive drum 131 (an example of a photosensitive unit), a charging device 132, and a cleaner 136. Each of the photosensitive unit 137 and the developing unit 134 is removable from the image forming apparatus main body.

  The fixing unit 140 fixes the toner image transferred onto the sheet. The fixing unit 140 is disposed downstream of the transfer roller 135 in the transport path RT. The fixing unit 140 includes a pressure roller and a heating roller.

  The ADF unit 160 sends the documents placed on the document tray 161 to the scanner 170 one by one.

  The scanner 170 reads an image of a document and creates image data.

  Subsequently, the configuration of the developing unit 134 and the periphery thereof in the image forming apparatus 100 of the present embodiment will be described.

  FIG. 2 is a perspective view showing the configuration of the developing unit 134 in an embodiment of the present invention.

  Referring to FIG. 2, the developing unit 134 includes a developing unit main body 301, a developing roller 302, developing unit supporting points 303 and 304, a developing roller gear 305, and rollers 306 and 307. An arrow AR1 indicates the insertion direction of the developing unit 134 when the developing unit 134 is attached to the image forming apparatus main body (hereinafter referred to as the insertion direction of the developing unit 134). The insertion direction of the developing unit 134 is parallel to the extending direction (longitudinal direction) of the developing roller 302.

  The developing unit main body 301 accommodates the developing roller 302. The developing roller 302 applies a developer to the photosensitive drum 131. A part of the developing roller 302 is accommodated inside the developing unit main body 301, and another part is exposed from the upper surface of the developing unit main body 301. The developing unit main body 301 and the developing roller 302 extend in the lateral direction in FIG.

  The developing unit 134 is rotatably supported relative to the image forming apparatus main body at each of the developing unit supporting points 303 and 304. Each of the developing unit fulcrums 303 and 304 constitutes a fulcrum shaft P 2 which is the center of rotation of the developing unit 134. The developing unit supporting point 303 is provided on the front side of the developing unit main body 301, and the developing unit supporting point 304 is provided on the rear side of the developing unit main body 301.

  The developing roller gear 305 transmits rotational force to the developing roller 302 and the like together with the main body side drive gear 251 (FIG. 3).

  The rollers 306 and 307 are provided on the outer periphery of the developing roller 302. Each of the rollers 306 and 307 is for achieving the accuracy of the gap between the developing roller 302 and the photosensitive drum 131.

  FIG. 3 is a perspective view showing the configuration of the image forming apparatus main body side supporting the developing unit 134. As shown in FIG.

  Referring to FIG. 3, image forming apparatus 100 further includes a main body side drive gear (main body side docking gear) 251 as a member on the image forming apparatus main body side. The developing unit 134 is connected to the main body side drive gear 251 coaxially with the fulcrum shaft P 2 by the developing unit fulcrum 304. When the developing unit 134 is attached to the image forming apparatus main body, the fulcrum shaft P2 is located above any roller (developing roller and agitating roller) included in the developing unit 134.

  FIG. 4 is a perspective view showing the configuration of the developing unit 134 and the periphery thereof when the developing unit 134 is mounted on the image forming apparatus main body in the embodiment of the present invention.

  Referring to FIG. 4, the photosensitive drum 131 is supported by the image forming apparatus main body at a position close to the developing roller 302. The image forming apparatus 100 further includes a lever unit 200 as a member on the image forming apparatus main body side. The lever unit 200 is provided on the left side of the developing unit 134 in FIG.

  The lever unit 200 includes an operating shaft 201, pressure contact levers 202 and 203 (an example of a pressure contact member), a separation lever 204 (an example of a separation member), and an operation lever 205 (an example of an operation member). The operating shaft 201 extends in parallel to the insertion direction of the developing unit 134 and the extending direction of the developing roller 302. The operation shaft 201 constitutes a fulcrum shaft P1 which is the center of rotation of the lever unit 200. The pressure contact levers 202 and 203, the separation lever 204, and the operation lever 205 are attached to the operation shaft 201, and rotate coaxially with the image forming apparatus main body.

  The pressure contact lever 202 is attached to the front end of the operation shaft 201. The pressure contact lever 203 is attached to the rear end of the operation shaft 201. The pressure levers 202 and 203 respectively project from the operation shaft 201 in the same direction on the developing unit 134 side.

  The separation lever 204 is attached only to the rear end of the operation shaft 201 in the insertion direction. The separation lever 204 is not attached to the front end in the insertion direction. The separation lever 204 protrudes from the operation shaft 201 in the direction of the developing unit 134 different from each of the pressure contact levers 202 and 203.

  The control lever 205 is for operating the rotation of each of the pressure contact levers 202 and 203 and the separation lever 204. The operation lever 205 protrudes from the operation shaft 201 on the opposite side to the developing unit 134 side.

  FIG. 5 is a perspective view showing the configuration in the vicinity of the separation lever 204 in the embodiment of the present invention. FIG. 5A shows a state in which the developing unit 134 is in contact with the pressure levers 202 and 203. FIG. FIG. 5B is a view showing the developing unit 134 in contact with the separation lever 204. In FIG. 5, the pressure contact lever 203 is omitted for the convenience of description.

  Referring to FIGS. 4 and 5, developing unit 134 further includes unit-side protrusion 311, unit-side engagement portion 312, and unit-side contact portions 313 and 315.

  The unit side contact portions 313 and 315 are provided on the outer surface of the developing unit main body 301 so as to face the lever unit 200. The unit side contact portion 313 is a portion in contact with the pressure contact lever 203. The unit side contact portion 315 (FIG. 4) is a portion in contact with the pressure contact lever 202.

  The unit side protrusion 311 protrudes from the unit side contact portion 313 toward the lever unit 200. The unit-side engagement portion 312 extends from near the tip of the unit-side protrusion 311 in parallel with the insertion direction of the developing unit 134 and the extending direction of the developing roller 302. The unit side engagement portion 312 is a portion in contact (engagement) with the spacing lever 204.

  The separation lever 204 includes a lever side protrusion 204 a and a lever side extension 204 b. The lever side protrusion 204 a protrudes from the operation shaft 201 toward the developing unit 134. The lever side extending portion 204 b extends in parallel with the operation shaft 201 from the vicinity of the tip of the lever side projecting portion 204 a.

  FIG. 6 is a partial sectional view showing the relationship between the lever unit 200 and the developing unit 134 in the embodiment of the present invention. FIG. 6A shows a state in which the developing unit 134 is in contact with the pressure levers 202 and 203. FIG. FIG. 6B shows the developing unit 134 in contact with the separation lever 204. As shown in FIG.

  Referring to FIGS. 5A and 6A, the pressure contact lever 203 is pivoted to a position in contact with the developing unit 134. In this case, each of the pressure contact levers 203 and 205 contacts each of the unit side contact portions 313 and 315, and applies a force indicated by an arrow AR3 to the developing unit 134. This force corresponds to the force for pressing the developing unit 134 against the photosensitive drum 131. The lever side extension portion 204 b of the separation lever 204 exists below the position between the developing unit main body 301 and the unit side engaging portion 312 and is not in contact with the developing unit 134.

  The accurate positioning of the developing unit 134 can be performed by pressing the developing unit 134 supported on the fulcrum shaft P2 and rotatable with respect to the photosensitive drum 131 using the two pressure levers 202 and 203. .

  When changing the lever unit 200 from the state shown in FIG. 5 (a) and FIG. 6 (a) to the state shown in FIG. 5 (b) and FIG. 6 (b) It is rotated in the direction shown by.

  Referring to FIGS. 5B and 6B, the separation lever 204 is pivoted to a position in contact with the developing unit 134. In this case, the lever side extension portion 204 b of the separation lever 204 exists at a position between the developing unit main body 301 and the unit side engagement portion 312. The surface on the operation shaft 201 side of the lever side extension portion 204 b is in contact (engagement) with the unit side engagement portion 312. The separation lever 204 applies a force in the direction indicated by the arrow AR4 to the unit side engagement portion 312. This force corresponds to the force for separating the developing unit 134 from the photosensitive drum 131. The pressure lever 203 is pivoted to the upper side of the unit side contact portion 313 and is not in contact with the developing unit 134.

  FIG. 7 is a cross-sectional view schematically showing a change in the contact position between the developing unit 134 and the pressure contact lever 203 or the separation lever 204 when the operation lever 205 is rotated in the direction indicated by the arrow AR2 (FIG. 4). It is. When the pressure lever 203 is at the position shown in FIG. 7A, the rotation angle of the operation lever 205 is 0 degrees. The rotation angle of the control lever 205 is increased in the order of FIG. 7 (b), FIG. 7 (c), FIG. 7 (d) and FIG. 7 (e).

  Referring to FIG. 7, the unit side contact portion 313 is provided with a recess 313 a. In the state shown in FIG. 7A, the tip of the pressure contact lever 203 is engaged with the recess of the recess 313a. In this state, the pressure with which the pressure contact lever 203 is in pressure contact with the photosensitive drum 131 with respect to the developing unit 134 is maximized.

  When the control lever 205 is pivoted in the direction indicated by the arrow AR2 from the state shown in FIG. 7A, the pressure contact lever 203 is gradually pivoted upward, and the contact position with the unit side contact portion 313 is shifted upward (FIG. 7 (b)). In the state of FIG. 7C, the pressure contact lever 203 is not in contact with the unit side contact portion 313. In the states shown in FIGS. 7D and 7E, the separation lever 204 engages with the unit side engaging portion 312, and starts to apply a force separating the developing unit 134 from the photosensitive drum 131. The separation lever 204 slides on a part of the developing unit 134 (the unit side engaging portion 312) to rotate the developing unit 134 in a direction to move away from the photosensitive drum 131.

  When the control lever 205 is rotated by a predetermined angle from the state shown in FIG. 7A, the separation lever 204 starts applying a force separating the developing unit 134 from the photosensitive drum 131. As a result, since the separating force can be applied to the developing unit 134 after the pressure contact pressure is reduced, the amount of operating force of the operating lever 205 can be reduced, and the operability can be improved.

  FIG. 8 is an enlarged view of FIG. 7 (c).

  Referring to FIG. 8, the lever side extension portion 204 b preferably includes a portion 204 c having an arc cross section, and the radius of curvature of the portion 204 c is larger than the radius of the unit side engagement portion 312. Thereby, the sliding between the separation lever 204 and the unit side engaging portion 312 becomes smooth.

  According to the above-described embodiment, in addition to the pressing lever coaxial with the rotating operation shaft, the spacing lever is provided, and the spacing lever applies a force for spacing the developing unit from the photosensitive drum. Thus, the developing unit can be easily separated from the photosensitive drum with a simple configuration.

  Further, since each of the pressure contact lever, the separation lever, and the operation lever is attached to the operation shaft and rotates coaxially, the developing unit can be separated from the photosensitive unit without impairing the operability.

  Further, since the separation lever is attached to the rear end of the operation shaft and not to the front end of the operation shaft, the separation lever does not interfere with the development unit when the developing unit is attached or detached. Operability can be maintained.

  In addition, even when the component to be rotated by the weight of the developing unit 134 is small such that the fulcrum shaft of the developing unit is substantially above the center of gravity of the developing unit, the developing unit can be reliably separated by the separation lever.

  Further, when the main body side drive gear for transmitting the drive to the developing unit is coaxial with the fulcrum shaft of the developing unit and the driving connection is separated, even if the developing unit is difficult to rotate due to the driving connection with the main body side. The separating lever can reliably separate the developing unit.

  Note that, as a modification of the present embodiment, a plurality of operation levers may be provided for operating the rotation of each of the pressure contact lever and the separation lever.

  The embodiments described above are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated not by the above description but by the claims, and is intended to include all the modifications within the meaning and scope equivalent to the claims.

100 image forming apparatus 110 sheet feeding unit 120 sheet conveyance unit 130 image forming unit 131 photosensitive drum 132 charging device 133 exposure device 134 developing unit 135 transfer roller 136 cleaner 137 photosensitive unit 140 fixing unit 150 sheet discharge tray 160 ADF (Auto Document) Feeder section 161 Document tray 170 Scanner 200 Lever unit 201 Operation shaft 202, 203 Pressure lever 204 Separation lever 204a Lever side protrusion 204b Lever side extension 205 Control lever 251 Main unit drive gear 301 Development unit main body 302 Development roller 303, 304 developing unit supporting point 305 developing roller gear 310 stirring roller 311 unit side protruding portion 312 unit side engaging portion 313 unit side contacting portion 13a recess 315 unit-side contact portion P2 fulcrum shaft RT transport path

Claims (5)

A photosensitive member supported by the image forming apparatus main body;
A developing unit including a developing roller that is detachable from the image forming apparatus main body, rotates about a fulcrum shaft when mounted on the image forming apparatus main body, and applies a developer to the photosensitive member;
A pressure contact member which applies a force to press the photosensitive member against the developing unit when the image forming apparatus is pivoted to the position where the image forming apparatus main body is rotated and brought into contact with the developing unit;
A separating member that applies a force for separating the developing unit from the photosensitive member when the image forming apparatus is rotated with respect to the image forming apparatus main body and rotated to a position contacting the developing unit;
An operation member for operating rotation of each of the pressure contact member and the separation member ;
And an operation shaft extending in parallel to the insertion direction of the developing unit when the developing unit is attached to the image forming apparatus main body,
Each of the pressure contact member, the spacing member, and the operation member is attached to the operation shaft and coaxially pivots;
When the operation member is rotated by a predetermined angle from the position of the operation member when the pressure contact member is in pressure contact with the photosensitive member with respect to the development unit, the separation member is relative to the development unit The image forming apparatus , which begins to apply a force separating it from the photosensitive member . The pressure contact member is
A first pressure contact member attached to a front end of the operation shaft in the insertion direction;
And a second pressure contact member attached to the rear end of the operation shaft in the insertion direction,
The image forming apparatus according to claim 1 , wherein the separation member is attached to a rear end of the operation shaft in the insertion direction and is not attached to a front end of the insertion shaft in the insertion direction. apparatus. The operation member is in a first state in which the developing unit and the pressing member are in contact with each other and the developing unit and the separating member are not in contact with each other, and the developing unit and the pressing member are not in contact with each other. wherein the spacer member to operate the rotation of each of said spacer member and said pressing member and a second state in contact with the image forming apparatus according to claim 1 or 2. It further comprises a main body side drive gear for transmitting a rotational force to the developing roller,
When the developing unit is mounted on the image forming apparatus main body, the fulcrum shaft is located above any of the rollers included in the developing unit, and the developing unit is coaxial with the fulcrum shaft and the body side drive is performed. The image forming apparatus according to any one of claims 1 to 3 , which is connected to a gear. The developing unit is
A developing unit main body that accommodates the developing roller;
A unit-side protrusion which protrudes from the developing unit body;
And a unit-side engaging portion extending from the unit-side protrusion in parallel to the insertion direction of the developing unit when the developing unit is attached to the image forming apparatus main body,
When the separating member is rotated to a position in contact with the developing unit, the photosensitive member is connected to the unit-side engaging portion between the developing unit main body and the unit-side engaging portion. The image forming apparatus according to any one of claims 1 to 4 , wherein a force for separating the developing unit is applied.