IMAGE FORMING APPARATUS

An image forming apparatus includes a duplex conveying unit, an intermediate conveying unit, a duplex conveying path, a main conveying path and a locking mechanism. The duplex conveying unit turnable around its lower end is provided in an aperture of an apparatus main body. The intermediate conveying unit turnable around its lower end is disposed inside the duplex conveying unit. The duplex conveying path is arranged between the duplex conveying unit and the intermediate conveying unit. The main conveying path is arranged inside the intermediate conveying unit. The locking mechanism couples the duplex conveying unit and the intermediate conveying unit by turning the duplex conveying unit and the intermediate conveying unit in an approaching direction to each other. The locking mechanism decouples the duplex conveying unit and the intermediate conveying unit by turning the duplex conveying unit and the intermediate conveying unit in a separating direction from each other.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese Patent application No. 2015-169570 filed on Aug. 28, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an image forming apparatus which includes a conveying unit arranging a conveying path.

In an image forming apparatus, such as a copying machine or a printer, a sheet is conveyed along a conveying path, such as a main conveying path running from a sheet feeding cartridge toward an image forming part or a duplex conveying path in which a top and a bottom of the sheet are reversed in order to carry out duplex printing. Such a conveying path is configured so as to be openable in order to easily deal with a sheet jam even in a case where the sheet jam occurs in the conveying path.

The image forming apparatus provided with the main conveying path and the duplex conveying path includes a duplex conveying unit provided in an aperture of an apparatus main body to be turnable around a lower end and an intermediate conveying unit disposed inside of the duplex conveying unit to be turnable around a lower end. Between the duplex conveying unit and the intermediate conveying unit, the duplex conveying path is arranged and, inside of the intermediate conveying unit, the main conveying path is arranged. In addition, the duplex conveying path is opened by turning the duplex conveying unit and the main conveying path is opened by turning the intermediate conveying unit.

In addition, the intermediate conveying unit and the duplex conveying unit may be provided to be integrally turnable for the sake of increasing efficiency of the work of dealing with the sheet jam. For example, there is an image forming apparatus including a coupling and decoupling mechanism capable of coupling and decoupling the intermediate conveying unit and the duplex conveying unit. In this image forming apparatus, the intermediate conveying unit and the duplex conveying unit are supported to be turnable around respective supporting shafts provided at different heights. By utilizing a difference between turning radiuses of both units, if a turning angle of the duplex conveying unit is increased, coupling is automatically released.

However, in the image forming apparatus mentioned above, because it is necessary to keep the height of the supporting shaft of the intermediate conveying unit and the height of the supporting shaft of the duplex conveying unit apart from each other at a predetermined distance, there is a problem that the image forming apparatus is enlarged. The image forming apparatus also may be configured so that the duplex conveying unit is provided with a lever and the intermediate conveying unit is held by the lever. However, in such a case, because the work of releasing the lever or the like is required when only the intermediate conveying unit is independently turned, the workability is impaired.

SUMMARY

In accordance with an embodiment of the present disclosure, an image forming apparatus includes a duplex conveying unit, an intermediate conveying unit, a duplex conveying path, a main conveying path and a locking mechanism. The duplex conveying unit is provided in an aperture of an apparatus main body to be turnable around a lower end thereof. The intermediate conveying unit is disposed inside the duplex conveying unit and provided to be turnable around a lower end thereof. The duplex conveying path is arranged between the duplex conveying unit and the intermediate conveying unit. The main conveying path is arranged inside the intermediate conveying unit. The locking mechanism couples the duplex conveying unit and the intermediate conveying unit to each other by turning the duplex conveying unit and the intermediate conveying unit in an approaching direction to each other. The locking mechanism also decouples the duplex conveying unit and the intermediate conveying unit from each other by turning the duplex conveying unit and the intermediate conveying unit in a separating direction from each other.

DETAILED DESCRIPTION

In the following, with reference to the drawings, an image forming apparatus according to an embodiment of the present disclosure will be described.

First, with reference toFIG. 1, entire structure of a color printer1as the image forming apparatus according to the embodiment of the present disclosure will be described.FIG. 1is a sectional view schematically showing an internal structure of the color printer. Incidentally, hereinafter, it will be described so that the front side of the color printer1is positioned at a left side ofFIG. 1and that left and right directions is defined as seen from the front side of the color printer1.

The color printer1includes, as shown inFIG. 1, a box-shaped apparatus main body2. On a front face of the apparatus main body2, a manual bypass tray3is provided and, on a rear face thereof, an aperture2ais formed. The aperture2ais opened and closed by a duplex conveying unit5supported to be turnable around a lower end thereof. Inside of the duplex conveying unit5, an intermediate conveying unit6is supported to be turnable around a lower end thereof. The duplex conveying unit5and the intermediate conveying unit6will be described later. Further, on an upper face of a top cover covering a top face of the apparatus main body2, an ejected sheet tray7onto which a sheet is ejected is formed.

At a lower part of the apparatus main body2, a sheet feeding cartridge9in which a sheet S is stored is attachably/detachably provided and, at a rear side of the sheet feeding cartridge9, a sheet feeding device10feeding the sheet from the sheet feeding cartridge9is provided. at an upper side of the sheet feeding cartridge9, an exposure device11composed of a laser scanning unit (LSU) is provided and, at an upper side of the exposure device11, an intermediate transferring belt14as an image carrier is rotatably supported. Along a lower part of the intermediate transferring belt14, four image forming parts15disposed for the respective colors of toners are provided.

In each image forming part15, a photosensitive drum16is rotatably provided and, around the photosensitive drum16, a charging device17, a development device18, a primary transferring roller20composing a primary transferring part19with an intermediate transferring belt14, a cleaning device21, and a static eliminator22are disposed in sequential order of primary transferring process. At an upper side of the intermediate transferring belt14, four toner containers23corresponding to the respective image forming parts15are installed for the respective colors of the toners (Y, M, C, K).

In addition, at a rear side of the intermediate transferring belt14, a secondary transferring roller25is rotatably supported on the intermediate conveying unit6and, between the intermediate transferring belt14and the secondary transferring roller25, a secondary transferring part26is arranged. At an upper side of the secondary transferring part26, a fixing device28is provided and, at an uppers side of the fixing device28, a sheet ejecting part29facing to the ejected sheet tray7is provided.

Inside of the apparatus main body2, a main conveying path30from the sheet feeding device10toward the sheet ejecting part29through the secondary transferring part26and the fixing device28is provided. The main conveying path30between the sheet feeding device10and the fixing device28is arranged on a front side of the intermediate conveying unit6. In the main conveying path30, a manual bypass conveying path31extending from the manual bypass tray3joins a joining part30aat a downstream side from the sheet feeding device10. The manual bypass conveying path31is composed of an upper guiding plate31aand a lower guiding plate31barranged in upward and downward directions in parallel to face to each other at a predetermined interval. Further, in the main conveying path30, a duplex conveying path32for duplex printing also joins the joining part30a. The duplex conveying path32is branched from the main conveying path30to a back face side at a downstream side from the fixing device28and arranged with a C-shaped cross section. The duplex conveying path32is arranged between a rear side face of the intermediate conveying unit6and a front side face of the duplex conveying unit5. At the joining part30a, an intermediate guide35is disposed.

In the main conveying path30, at the downstream side from the joining part30a, a pair of resist rollers37are provided. One roller37aof the pair of resist rollers37is supported on the intermediate conveying unit6.

Next, an image forming operation of the color printer1having such configuration will be described. In each image forming part15, after a surface of the photosensitive drum16has been electrically charged by the charging device17, exposure corresponding to image data is carried out with respect to the photosensitive drum16by laser light from the exposure device11and an electrostatic latent image is formed on the surface of the photosensitive drum16. The electrostatic latent image is developed as a toner image of a corresponding color by the development device18and the toner image is primarily transferred onto the surface of the intermediate transferring belt14in the primary transferring part19. the above-described operation is sequentially repeated by the respective image forming parts15and a full-color toner image is thereby formed on the intermediate transferring belt14. Incidentally, the toner and electric charge having remained on the photosensitive drum16are removed by the cleaning device21and the static eliminator22.

On the other hand, the sheet having been fed out from the sheet feeding cartridge9by the sheet feeding device10is conveyed to the secondary transferring part along the main conveying path30at a synchronized timing with the image forming operation described above and, in the secondary transferring part26, the full-color toner image on the intermediate transferring belt14is secondarily transferred onto the sheet. The sheet onto which the toner image has been secondarily transferred is conveyed to the downstream side in the main conveying path30and advanced to the fixing device28, and then, in the fixing device28, the toner image is fixed onto the sheet. The sheet onto which the toner image has been fixed is ejected from the sheet ejecting part29to the ejected sheet tray7.

In addition, the sheet having been conveyed from the manual bypass tray3along the manual bypass conveying path31is guided to the main conveying path30at the joining part30by the intermediate guide35, and then, the image forming operation is carried out similarly. In a case where duplex printing is carried out, the sheet with an image being formed onto one face thereof is conveyed to the joining part30athrough the duplex conveying path32and guided to the main conveying path30at the joining part30aby the intermediate guide35, and then, the image forming operation is carried out similarly.

Next, with reference toFIG. 2toFIG. 4, the duplex conveying unit5and the intermediate conveying unit6will be described.FIG. 2is a perspective view showing the duplex conveying unit and the intermediate conveying unit,FIG. 3is a side view showing the duplex conveying unit and the intermediate conveying unit coupled to each other andFIG. 4is a side view showing the duplex conveying unit and the intermediate conveying unit decoupled from each other.

As described above, the duplex conveying unit5is provided in the aperture2aof the apparatus main body2, and the intermediate conveying unit6is provided inside of the duplex conveying unit5. The duplex conveying unit5and the intermediate conveying unit6are provided with a locking mechanism40coupling both units5and6to each other by turning both units5and6in an approaching direction to each other and decoupling both units5and6from each other by turning both units5and6in a separating direction from each other.

First, the duplex conveying unit5will be described. The duplex conveying unit5includes a cover plate41covering the aperture2aof the apparatus main body2and a guiding part42provided on a front face of the covering plate41.

A front face42aof the guiding part42curves in a substantial C-shape as viewed from the lateral side, has a plurality of ribs formed along the upward and downward direction and has conveying rollers44rotatably supported at predetermined intervals. In addition, on left and right side faces42bof the guiding part42, arm pieces45protruding downwardly from its lower edge are extended. At lower ends of the respective arm pieces45, supporting shafts46are coaxially formed. Each supporting shaft46is pivoted to a pivoting part (not shown) formed inside of the aperture2a, and thereby, the duplex conveying unit5turns around the supporting shaft46between a closed position at which the aperture2ais closed and an open position at which the aperture2ais opened.

Further, on left and right side faces42bof the guiding part42, opening and closing levers48for engaging with and disengaging from the apparatus main body2are supported at respective positions at slightly upper side positions from a center in a height direction. In each opening and closing lever48, a claw part48aprotruding upwardly is formed at a distal end thereof and the claw part48ais supported by an elastic member (not shown) in a posture protruded forwardly from the front face42aof the guiding part42.

Furthermore, at lower ends of the left and right side faces42bof the guiding part42, apertures51(refer toFIG. 4) are formed. In the apertures51, stoppers53constituting the locking mechanism40are supported so as to be capable of advancing and retracting in a direction crossing a turning direction of the duplex conveying unit5. The stopper53will be described later.

Next, the intermediate conveying unit6will be described. The intermediate conveying unit6has a height of the order of approximately half of the duplex conveying unit5and includes a front plate57, a rear plate58and left and right side plates59as shown inFIG. 4. On the front plate57, a plurality of ribs along the upward and downward directions are formed and, between the front plate57and the apparatus main body2, the main conveying path30is arranged. In addition, on the front plate57, as described above, one roller37aof the pair of resist rollers37and the secondary transferring roller25are disposed at a predetermined interval along a conveyance direction. On the rear plate58as well, a plurality of ribs along the upward and downward directions are formed and, between the rear plate58and the front face42aof the guiding part42of the duplex conveying unit5, the duplex conveying path32is arranged.

On the left and right side plates59, left and right arm pieces60protruding diagonally backward and downward from their lower edges are extended. At lower ends of the respective left and right arm pieces60, pivoting parts61are coaxially formed. Each pivoting part61is pivoted to each supporting shaft46of the duplex conveying unit5. In this manner, the intermediate conveying unit6turns around the supporting shafts46of the duplex conveying unit5between the closed position when the main conveying path30is arranged between the intermediate conveying unit6and the apparatus main body2and the open position when the main conveying path30is opened.

In addition, on the left and right side plates9, locking levers62interlocking with the opening and closing levers48of the duplex conveying unit5are supported. Each locking lever62is formed in an L-shape as viewed from the lateral side, a distal end thereof is disposed so as to face to the opening and closing lever48from a lower side and a proximal end thereof is rotatably supported at a lower side of the secondary transferring roller25. Moreover, to both ends of a rotating shaft25aof the secondary transferring roller25are rotatably coupled to linking members63and linking members63are rotatably coupled in the vicinity of the centers of the locking levers62.

Further, on the left and right side plates59, at an upper side of the left and right arm pieces60, longitudinally elongated apertures65as depressions constituting the locking mechanism40together with the stoppers53as mentioned above are formed. Each aperture65is formed on a turning trajectory of each stopper53when the intermediate conveying unit6is turned around the supporting shafts46. In addition, on the front side (a rear side) from the apertures65in a direction of the intermediate conveying unit6approaching the duplex conveying unit5, pressing faces66as an abutment part constituting the locking mechanism40are formed. Each pressing face66is formed so as to incline in an outside direction along the approaching direction.

Next, with reference toFIG. 5andFIG. 6, the locking mechanism40will be described.FIG. 5is a perspective view showing the locking mechanism andFIG. 6is a transverse sectional view of the stopper. As shown inFIG. 5, the locking mechanism40is composed of the stoppers53supported in the apertures51formed in the left and right side faces42bof the guiding part42of the duplex conveying unit5and the apertures65and the pressing faces66formed in the left and right side plates of the intermediate conveying unit6, as described above.

With reference toFIG. 6, each stopper53will be described. The aperture51supporting the stopper53is formed in a rectangular shape and, at front and rear edges of the aperture51, guiding walls51aextending to the inside are formed. Also, inside of the aperture51, a supporting wall51bfacing to the aperture51is formed and, on the supporting wall51b, a boss51cis erected so as to face to the aperture51.

The stopper53is a hollow-shaped member having an opened rear end face and having a distal end71formed in a triangular shape in a planar view. The distal end71has a depth side inclined face71aon the depth side (a rear side) and a near side inclined face71bon the near side (a front side) in a direction of the duplex conveying unit5approaching the intermediate conveying unit6. Here, an inclination angle α of the depth side inclined face71awith respect to the approaching direction is set greater than an inclination angle β of the near side inclined face71bwith respect to the approaching direction.

On a side face of the stopper53, a flange73overhanging in the outside direction is formed along the outer circumference. Also, in a hollow part of the stopper53, a stepped part75is formed between a large diameter part at the rear end side and a small diameter part at the distal end side.

The stopper53is disposed between guiding walls51ainside of the aperture51and the distal end71is biased by a coil spring77so as to protrude from the aperture51. In the coil spring77, a distal end thereof is engagingly locked with the stepped part75of the hollow part and a rear end thereof is engagingly locked with the boss51cof the supporting wall51b. The stopper53is biased by the coil spring77, and then, until the flange73is engagingly locked with an end face of the guiding wall51a, the distal end71is guided along a space between guiding walls51aand advanced in the outside direction from the aperture51. On the other hand, if the distal end71is pushed into the aperture51against a biasing force of the coil spring77, as indicated by a two-dot chain line inFIG. 6, the stopper53is retracted in the aperture51.

In the color printer1having the above-described configuration, the duplex conveying unit5and the intermediate conveying unit6are coupled to each other by the locking mechanism40. That is, the stopper53of the duplex conveying unit5is biased by the coil spring77and the distal end71is advanced and fitted into the aperture65of the intermediate conveying unit6, and thereby, both units5and6are coupled to each other. Incidentally, in the stopper53, a portion at a rear end side from the distal end71is advanced into the aperture65. In addition, the rotating shaft25aof the secondary transferring roller25is engaged with an engaging part (not shown) formed in the apparatus main body2so that the secondary transferring roller25faces to the intermediate transferring belt14(refer toFIG. 1). Since the rotating shaft25aof the secondary transferring roller25is thus engaged with the apparatus main body2, the intermediate conveying unit6is maintained at the closed position and the main conveying path30is arranged. Moreover, the duplex conveying unit5coupling to the intermediate conveying unit6is also maintained at the closed position and the duplex conveying path32is arranged.

In a case where a sheet jam occurs in the main conveying path30, the duplex conveying unit5and the intermediate conveying unit6coupled to each other are integrally turned. At this time, if the opening and closing levers48are turned downwardly, the locking levers62are pushed downwardly by the opening and closing levers48and turned downwardly around the supporting shafts. Accordingly, via the linking members63coupling to the locking levers62, the turning shaft25aof the secondary transferring roller25is moved and decoupled from the engaging part of the apparatus main body2. In this manner, the intermediate conveying unit6becomes turnable with respect to the apparatus main body2and the main conveying path30is opened.

In a case where a sheet jam occurs in the duplex conveying path32, in a state in which the duplex conveying unit5and the intermediate conveying unit6are turned, both units5and6are turned in the separating direction from each other.

Accordingly, in the locking mechanism40, as shown inFIG. 7toFIG. 9, the intermediate conveying unit6and the duplex conveying unit5are decoupled from each other.FIG. 7toFIG. 9are perspective views usable to describe engaging and disengaging states of the locking mechanism, whereFIG. 7shows a state that the stopper is fitted into the aperture,FIG. 8shows a state that the stopper is pressed by the inclined face and retracted andFIG. 9shows a state that the stopper is completely separated from the aperture. Incidentally, inFIG. 7toFIG. 9, the coil spring is not shown.

As shown inFIG. 7, at the time of coupling of both units5and6to each other, the stopper53is biased by the coil spring77and the distal end71is advanced and fitted into the aperture65and both units5and6are coupled to each other.

If the intermediate conveying unit6is turned in the separating direction from the duplex conveying unit5, the pressing face66of the intermediate conveying unit6abuts against the depth side inclined face71aof the distal end71of the stopper53to press the depth side inclined face71ain an inside direction and the stopper53is retracted between the guiding walls51aagainst the biasing force of the coil spring77. Here, the pressing face66includes an edge65aat the rear side of the aperture65. Then, the distal end71is separated from the aperture65and, as shown inFIG. 8, an apex of the distal end71abuts against the pressing face66. In this manner, the intermediate conveying unit6and the duplex conveying unit5are decoupled from each other and the duplex conveying path32becomes openable. While the distal end71is pressed against the pressing face66, the stopper53is retracted. If the pressing face66is completely separated from the aperture51, as shown inFIG. 9, the stopper53is biased by the coil spring77, and then, the distal end71is advanced from the aperture51.

After dealing with the sheet jam in the duplex conveying path32has completed, if the intermediate conveying unit6is turned in the approaching direction to the duplex conveying unit5, in the locking mechanism40, the pressing face66abuts against the near side inclined face71bat the distal end71of the stopper53to presses the stopper53in the inside direction, and then, the stopper53is retracted between the guiding walls51aagainst the biasing force of the coil spring77(refer toFIG. 8). Further, if the intermediate conveying unit6is turned, the distal end71of the stopper53reaches the aperture65from the pressing face66, the stopper53is biased by the coil spring77and advanced, and then, the distal end71is fitted into the aperture65(refer toFIG. 7). In this manner, the intermediate conveying unit6and the duplex conveying unit5are coupled to each other.

Incidentally, the distal end71is formed so that the inclination angle α of the depth side inclined face71ais set greater than the inclination angle β of the near side inclined face71b. Therefore, a force of the pressing face66pressing the depth side inclined face71awhen the duplex conveying unit5and the intermediate conveying unit6are turned in the separating direction from each other, namely, when both units5and6are decoupled from each other, is greater than a force of the pressing face66pressing the near side inclined face71bwhen the duplex conveying unit5and the intermediate conveying unit6are turned in the approaching direction to each other, namely, when both units5and6are coupled to each other.

After the intermediate conveying unit6and the duplex conveying unit5have been thus coupled to each other, both units5and6are turned to the closed position, the rotating shaft25aof the secondary roller25is engaged with the engaging part of the apparatus main body2, and thereby, both units5and6are maintained at the closed position.

As described above, in the color printer1of the present disclosure, the intermediate conveying unit6and the duplex conveying unit5are coupled to each other to become integrally turnable by turning both units in the approaching direction to each other and decoupled from each other merely by the work of turning both units in the separating direction from each other. Therefore, it is possible to easily open the main conveying path30and the duplex conveying path32and to easily carry out the work of dealing with the sheet jam.

In addition, since the locking mechanism40is a simple configuration fitting the stopper53into the aperture65, it is possible to simplify the configuration of both units5and6. Further, in the locking mechanism40, a force of retracting the stopper53when the intermediate conveying unit6and the duplex conveying unit5are decoupled from each other is greater than a force of retracting the stopper53when the intermediate conveying unit6and the duplex conveying unit5are coupled to each other. Namely, since both units5and6are hardly decoupled from each other, when both units5and6are integrally turned, these units are not needlessly decoupled from each other. On the other hand, both units5and6can be coupled to each other with a comparatively small force. Also, since the locking mechanism40is formed at a position comparatively close to the supporting shaft46, even if a turning angle of the intermediate conveying unit6with respect to the duplex conveying unit5is small, both units can be decoupled. That is, by slightly turning the intermediate conveying unit6with respect to the duplex conveying unit5, it is possible to decouple both units.

In addition, since the intermediate conveying unit6and the duplex conveying unit5are turned around the same supporting shaft46, it is possible to broaden a range of turning of both units5and6and to easily carry out the work of dealing with the sheet jam. Moreover, it is possible to downsize the color printer1. Incidentally, the intermediate conveying unit6and the duplex conveying unit5may be configured so as to be turnable around different supporting shafts.

Further, by engaging the rotating shaft25aof the secondary transferring roller25supported on the intermediate conveying unit6with the apparatus main body2, the intermediate conveying unit6is engagingly locked at the closed position and the main conveying path30is arranged. In this manner, it is possible to enhance transferring accuracy in a case where the secondary transferring roller25transfers the toner image onto the sheet conveyed along the main conveying path30. Furthermore, by operation of the opening and closing levers48, the rotating shaft25aof the secondary transferring roller25can be engaged with and disengaged from the apparatus main body2via the locking levers62and the linking members63. In this manner, by way of a simple mechanism, positioning of the secondary transferring roller25with respect to the intermediate conveying transferring belt14and arranging of the main conveying path30by engagingly locking the intermediate conveying unit6with the apparatus main body2can be achieved.

In the above-mentioned embodiment, an example of supporting the stopper53on the duplex conveying unit5and forming the aperture65and the pressing face66on the intermediate conveying unit6was described. However, another embodiment may be configured so that the stopper53is supported on the intermediate conveying unit6and the aperture65and the pressing face66are formed on the duplex conveying unit5.

Further, the above-description of the embodiments was described about one example of the image forming apparatus including this according to the present disclosure. However, the technical scope of the present disclosure is not limited to the embodiments. Components in the embodiment described above can be appropriately exchanged with existing components, and various variations including combinations with other existing components are possible. The description of the embodiment described above does not limit the content of the disclosure described in the claims.