Image forming apparatus with an exterior cover operable to actuate a releasing mechanism and to serve as a handle

An image forming apparatus includes: a main body; a unit withdrawably mounted in the main body; an exterior cover attached on a front face of the unit; a rail carrying the unit, the rail being withdrawable outwardly from the main body; a rail guide member for supporting the rail slidably; a locking mechanism for restricting movement of the unit and the rail; and a releasing mechanism for releasing the restriction of the locking mechanism. In the image forming apparatus, the exterior cover is operable to actuate the releasing mechanism and serve as a handle for the unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to image forming apparatuses such as a copying machine and a printer. More particularly, it relates to an image forming apparatus comprising a unit withdrawably mounted in an apparatus main body.

2. Description of the Related Art

There exists a known image forming apparatus in which a fixing unit including members for performing fixing of a toner image to a recording sheet and is withdrawably mounted in an apparatus main body. In such apparatus, a locking mechanism is provided so as to restrict a movement of the fixing unit at the time when such movement is not needed. However, in a conventional technology, an operation lever for unlocking the locking mechanism provided in the fixing unit had been such a large part extending in a longitudinal direction of the fixing unit that space-saving in the image forming apparatus was prevented.

In view of the above, a various kinds of locking mechanisms which are compact and easy in operation for locking the fixing unit have been proposed. For example, in a construction disclosed in Japanese Unexamined Patent Publication No. HEI8-44131, a movable body which is connected rotatably to a main body of an image forming apparatus by a hinge is provided, and a predetermined locking engaging member is provided in the movable body on which the fixing device is mounted and in the main body of the image forming apparatus. Further, in Japanese Unexamined Patent Publication No. 2003-241615, a fixing device including a cover member serving as a handle gripped at the time of moving the fixing device and as an operating portion of the locking mechanism is disclosed.

However, in the construction disclosed in the Japanese Unexamined Patent Publication No. HEI8-44131, strength of the exterior cover is likely to be lowered since a part of the exterior cover is cut off and an operation lever for the locking mechanism is provided therein. Consequently, it would be necessary to add strength separately, or the part itself becomes larger and may prevent downsizing of the apparatus.

Further, in a construction disclosed in the Japanese Unexamined Patent Publication No. 2003-241615, a fixing cover is separately provided at an inner part of the exterior cover of the apparatus. Therefore, a user may be required to withdraw the fixing device by gripping the fixing cover after opening the exterior cover. It increases a number of operations needed for withdrawing the fixing device. Further, in the case of an image forming apparatus provided with a sheet conveyance passage between the fixing unit and the exterior cover, the operating lever of the locking mechanism prevents a conveyance of a recording sheet. Furthermore, there was a problem that a space between the exterior cover and the fixing unit for treating operation of sheet jamming becomes narrow.

SUMMARY OF THE INVENTION

In view of the above-described problems, an object of the present invention is to provide an image forming apparatus including a withdrawing mechanism and a locking mechanism for a unit which saves a space and is excellent in operability.

The image forming apparatus according to an embodiment of the present invention accomplishing the object comprises: a main body; a unit withdrawably mounted in the main body; an exterior cover attached on a front face of the unit; a rail carrying the unit, the rail being withdrawable outwardly from the main body; a rail guide member for supporting the rail slidably; a locking mechanism for restricting movement of the unit and the rail; and a releasing mechanism for releasing the restriction of the locking mechanism, wherein the exterior cover is operable to actuate the releasing mechanism and serve as a handle for the unit.

According to the construction, the exterior cover which constitutes a part of an exterior surface of the apparatus main body serves as a member for actuating the releasing mechanism of the locking mechanism of the unit and as a handle portion for withdrawing the unit from the main body of the apparatus. Thus, it becomes easier to withdraw the unit, and it would not be necessary to provide a separate operating lever for releasing the locking mechanism. Accordingly, it contributes to reducing of a number of parts and downsizing of the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the invention is described with reference to drawings.

FIG. 1is a front sectional view for describing an internal structure of an image forming apparatus100according to an embodiment of the invention. In the present embodiment, a digital composite machine is described as an example of the image forming apparatus100.

The image forming apparatus includes in its apparatus main body1an image forming section2for transferring an image onto a recording sheet9, a sheet feeding mechanism10for storing a stack of the recording sheets9and feeding the recording sheets9to the image forming section2, a fixing unit15for fixing an image onto the recording sheet9to which a transfer of the image is executed in the image forming section2and an image reading section5for reading out a document image.

The sheet feeding mechanism10is detachably mounted in the apparatus main body1and includes a plurality of sheet feeding cassettes10a,10b,10cfor storing recording sheets9and a stack bypass (manual feeding tray)10dprovided in upper part of the sheet feeding cassettes10a,10b,10c. The recording sheets9stored in the sheet feeding cassette10a,10b,10care sent out by a sheet feeding roller11one after another and fed to the image forming section2through a sheet conveyance passage12and a pair of registration rollers13.

The image forming section2executes transferring process to the recording sheets9based on image data read out in the image reading section5or electrically transferred from a computer and the like. The image forming section2includes a photoconductive drum4mounted rotatably about a shaft (direction A indicated by an arrow inFIG. 1) extending in forward and backward directions (direction perpendicular to a sheet ofFIG. 1) of the apparatus. Further, a charging unit3, an exposing unit (laser scanning unit and the like)8, a developing unit7, a transferring roller14and a cleaning device16are provided successively around the photoconductive drum4.

On a peripheral surface of the photoconductive drum4, an electrostatic latent image and a toner image based on the electrostatic latent image are formed. For the photoconductive drum4, a drum on which a layer of amorphous silicon is formed can be preferably used.

The charging unit3charges an electric charge on the peripheral surface of the photoconductive drum4which is rotated in a direction of the arrow A about the shaft. The charging unit3applies electric charge on the peripheral surface of the photoconductive drum4by a corona charge. In place of the charging unit3, the charging roller may be adopted.

The exposing unit8irradiates a laser light ray having a proper strength based on an image data to be formed to the peripheral surface of the photoconductive drum4. The irradiated laser light ray erases an electric charge on the photoconductive drum4so as to form the electrostatic latent image on the peripheral surface of the photoconductive drum4.

The developing unit7feeds a developer (hereinafter, referred to as toner particles) to the peripheral surface of the photoconductive drum4to thereby attach toner particles to portions of the peripheral surface on which the electrostatic latent image is formed. Accordingly, a toner image is formed on the peripheral surface of the photoconductive drum4. The toner particles are supplied to the developing unit7from a toner container6.

The transferring roller14makes the positively charged toner image formed on the peripheral surface of the photoconductive drum4transferred to the recording sheet9sent to the peripheral surface of the photoconductive drum4. To realize this operation, the transferring roller14applies negative electric charge having an inversed polarity with respect to the electric charge of the toner image to the recording sheet9. Thus, the recording sheet9sent to an immediately downward position of the photoconductive drum4is negatively charge while being pressingly nipped by the transferring roller14and the photoconductive drum4, and then the toner image on the positively charged peripheral surface of the photoconductive drum4is peeled off toward the surface of the recording sheet9. Accordingly, the transferring process of the toner image to the recording sheet9is performed.

The cleaning device16cleans up toner particles or other attached object resided on the peripheral surface of the photoconductive drum4after the transferring process. In the cleaning device16, a cleaning roller which comes in contact with the peripheral surface of the photoconductive drum4is provided. By a rotation of the cleaning roller, the resided toner particles and objects attached on the photoconductive drum4are cleaned. A portion of the peripheral surface of the photoconductive drum4cleaned by the cleaning device16moves to the charging unit3again for the next image forming process.

The fixing unit15is adapted for fixing the toner image transferred to the recording sheet9in the image forming section2by heat. The fixing unit15includes a fixing roller for applying heat to the recording sheet9and a pressing roller facing the fixing roller. After the transferring process, the recording sheet9is sent to a nip portion formed between the fixing roller and the pressing roller. By passing through the nip portion, the recording sheet9receives heat from the fixing roller so that the fixing process is executed thereto.

After passing through the fixing unit15, a conveyance direction of the recording sheet9is directed to either one of the conveyance passages branched off in a plurality of directions by a branching member17. In the case of forming the image only on one side of the recording sheet9, the recording sheet9passes through a pair of side discharging rollers18and is discharged onto a sheet discharging tray19in a state where the image surface of the recording sheet9is kept facing upward (face up). Or, the recording sheet9is conveyed to a sheet conveyance passage20extending in upward direction by the branching member17and discharged to the intermediate discharging tray23through a pair of intermediate discharging rollers22in a state where the image surface of the recording sheet9is kept facing downward (face-down). The sheet conveyance passage20, the pair of conveyance rollers21and the pair of intermediate discharging rollers22serves also as a switchback device for switching a conveyance direction of the recording sheet9.

On the other hand, in the case of forming images on both sides of the recording sheet9, after passing through the fixing unit15, the recording sheet9is conveyed to the sheet conveyance passage20by the branching member17. Then, after a rear end of the recording sheet passes through the branching member17, the pair of conveyance rollers21and the pair of intermediate discharging rollers22are rotated reversely so that the conveyance direction is switched. Thereafter, the recording sheet9is conveyed to a double-face printing passage24by the branching member17and conveyed to the image forming section2again in the state where a side of the recording sheet9not being formed an image faces upward. On the recording sheet9conveyed again to the image forming section2, the next image is formed. Then, the recording sheet9is conveyed to the fixing unit15, and the image formed on the recording sheet9is fixed. Thereafter, the recording sheet9is discharged to outside of the apparatus by the pair of side discharging rollers18or by the pair of intermediate discharging rollers22.

In such image forming apparatus100as described above, the fixing unit15is mounted in the apparatus main body1withdrawably in a direction parallel to the sheet conveyance direction. Consequently, even in the case where the recording sheet9is jammed in a vicinity of the fixing unit15, the recording sheet9can be removed easily.

FIG. 2is a perspective view showing the fixing unit15withdrawably mounted. As shown inFIG. 2, the main body of the fixing unit15(including the fixing roller, the pressing roller and the like) is placed on two rails30a,30b. The rails30a,30bare slidable in a horizontal direction along an unillustrated rail guide provided in one side of the apparatus main body1(directions of arrow A-A′). The fixing unit15is provided with a fixing input gear31and driving gears32,33,34as a driving system. The driving gears32,33,34are adapted for transmitting a driving force generated by an unillustrated fixing driving motor (driving means) to the fixing input gear31.

In the case where a sheet jamming occurs in a vicinity of a mounting portion of the fixing unit15, the fixing unit15is withdrawn together with the rails30a,30bby a user in the direction A from the apparatus main body1. Accordingly, the fixing input gear31is detached from the gear32so that driving of the fixing unit15is stopped. Then, after the jamming is treated and the fixing unit15is inserted toward the direction of the arrow A′, the fixing input gear31is engaged with the gear32.

Next, a withdrawing mechanism and a locking mechanism of the fixing unit15are specifically described.FIG. 3is a perspective view in a view point from inner part of the apparatus showing a construction of a vicinity of an exterior cover in the state where the fixing unit15is mounted in.FIG. 4is a side view showing a vicinity of the exterior cover in the state where the fixing unit15is mounted in. For convenience in description, a main body of the fixing unit15(refer toFIG. 2) is not illustrated inFIGS. 3 and 4.

In addition to the main body and the rails30a,30bshown inFIG. 2, the fixing unit15includes a conveyance guide member35. Further, an exterior cover40constituting a part of the external surface of the apparatus main body1is attached on an outer side of the conveyance guide member35(a front face of the fixing unit15).

The conveyance guide member35is a guide member (described as a branching member17inFIG. 1) for guiding the recording sheet9which has passed through a fixing roller of the fixing unit15to the sheet conveyance passage20, the opposite sides printing passage24(refer toFIG. 1) or a side discharging portion25provided in an exterior cover40. The conveyance guide member35is fixed on leading edges of the two rails30a,30bso as to bridge the rails.

On the conveyance guide member35, a side discharging roller18ais provided. The side discharging roller18ais rotated in a sheet discharging direction by an unillustrated driving means. A pair of side discharging rollers18are constructed by the side discharging roller18aand a discharging roller18b. The discharging roller18bpressingly comes in contact with the side discharging roller18aprovided in the exterior cover40and is rotationally driven. On a sheet conveyance surface35aof the conveyance guide member35, a guide roller41for smoothly conveying the recording sheet is provided.

The exterior cover40does not only constitutes a mere part of an exterior surface of the apparatus main body1but also serves as a handle used in a case of withdrawing the fixing unit15from the apparatus main body1or in a case of mounting the fixing unit15in the apparatus main body1.

On upper portions of opposite ends of the exterior cover40, a pair of a hooking member38projects toward inner part of the apparatus main body1. The hooking member38and an engaging pin42provided on a side of the apparatus main body1constitute the locking mechanism. Namely, the hooking member38engages with the engaging pin42so that a movement of the fixing unit15and the rails30a,30bin a horizontal direction is restricted.

The exterior cover40is rotatably attached to the conveyance guide member35with a rotational movement supporting point39projecting from inner surface of the hooking member38. Accordingly, the exterior cover40is rotated in directions of arrows B-B′ together with the hooking member38. In other words, the exterior cover40is shiftable over a vertical posture (a first posture as referred toFIGS. 3 and 4) and a rotated posture (a second posture as referred toFIGS. 5 and 6). In the vertical posture, an entirety of the exterior cover40comes close to the conveyance guide member35(the fixing unit15) so that the exterior cover40is not rotated substantially. In the rotational posture, the exterior cover40is rotated a predetermined angle about a rotational movement supporting point39from the vertical posture so that a lower portion of the exterior cover40is separated from the conveyance guide member35. The exterior cover40serves also as a releasing lever (releasing mechanism) for releasing the engagement of the hooking member38and the engaging pint42by its rotation. Further, the exterior cover40is biased in a direction of the arrow B′ by a torsion spring43provided in the rotational movement supporting point39.

FIG. 5is a perspective view in a view point from an inner part of the apparatus showing a construction of a vicinity of the exterior cover40in the state where the fixing unit15is withdrawn.FIG. 6is a side view showing the state same as that ofFIG. 5. A withdrawing mechanism of the fixing unit15is specifically described with reference to these Figures. At first, if the user grasps the lower end portion of the exterior cover40to withdraw the fixing unit15, the exterior cover40is rotated a predetermined angle in a direction of the arrow B about the rotational movement supporting point39while resisting against the biasing force generated by the torsion spring43.

With the rotational movement of the exterior cover40, the hooking member38is also rotated a predetermined angle in a direction of the arrow B. Accordingly, as shown inFIG. 6, the engagement of the hooking member38and the engaging pin42is released. Consequently, the fixing unit15and the rails30a,30bbecome movable in a horizontal direction. Thus, by grasping the exterior cover40and withdrawing the same in a direction of the arrow A, the fixing unit15is withdrawn with the rails30a,30boutwardly from the apparatus main body1.

Namely, the exterior cover40is so constructed as to serve as a handle for withdrawing the fixing unit15and as a releasing lever for the locking mechanism. Accordingly, components of the locking mechanism can be reduced and placed in a space-conserving manner. Further, since it is not necessary to form notches and the like in the exterior cover40, strength and the design of the exterior cover40is improved. Furthermore, since the locking mechanism can be released while the exterior cover40is grasped, operability of the fixing unit15at the time of withdrawing the exterior cover40is improved.

Since the fixing unit15is withdrawn together with the rails30a,30b, the user can easily treat jamming occurred in a vicinity of the fixing unit15and replace the fixing unit15. Further, in the case where the double-face printing passage24is provided between the conveyance guide member35and the exterior cover40(an arrow C inFIG. 6), the user can easily treat jamming occurred in a vicinity of the double-face printing passage24by rotating the exterior cover40in a direction of the arrow B.

If the fixing unit15is inserted toward the inner part of the apparatus main body1, at first, an inclined surface38aof a leading end of the hooking member38runs upon the engaging pin42and then the rotates in a direction of the arrow B. Then, when the fixing unit15is mounted at a predetermined position, the inclined surface38agets over the engaging pin42. Thus, the hooking member38is rotated in the direction of the arrow B′ by the torsion spring43and is engaged with the engaging pin42. Accordingly, the locking mechanism can be actuated by only pressing the exterior cover40in a direction of the arrow A′ so that operability at the time of inserting the fixing unit15is improved.

Further, as long as it is so constructed that the hooking member38is rotated in accordance with a rotation of the exterior cover40in the same direction, it is not necessarily the case that the rotational movement supporting point of the exterior cover40and the hooking member38are made the same. For example, the hooking member38may be provided in a side of a rotational edge of the exterior cover40. In such a case, the engaging pin42on the side of the apparatus main body1is placed in accordance with a position of the hooking member38.

Furthermore, the rotational movement supporting point39of the exterior cover40and of the hooking member38is provided on an upper end of the exterior cover40herein so that the fixing unit15is withdrawn by grasping a lower end of the exterior cover40. In place of this construction, the rotational movement supporting point39can be provided at a lower end of the exterior cover40so as to make the upper end portion a handle. In such a case, the hooking member38may be positioned so that opening faces downward. Accordingly, engagement of the hooking member38and the engaging pin42is released by a rotation of the upper end of the exterior cover40.

Furthermore, there is no limit on a rotational angle of the exterior cover40as long as the angle is larger than the value at which the engagement between the hooking member38and the engaging pin42is released. However, if the rotational angle is too large, operability at the time of withdrawing the fixing unit15by grasping the exterior cover40gets worse. Thus, it is preferable that the angle is set to be a minimum value at which the engagement between the hooking member38and the engaging pin42can be released.

The present invention is not limited to the embodiments described above, and other various modifications can be made within an area not departing from a purpose of the invention. For example, in the embodiment, the image forming apparatus100having a construction of withdrawing the fixing unit15horizontally in the sheet conveyance direction is described. However, the unit which is withdrawn outwardly from the apparatus is not limited to the fixing unit15. For example, it may be other unit such as a transferring unit including a transferring roller14. Further, it may be so constructed that the fixing unit15is withdrawn together with other units.

Further, in the above-described embodiment, the case where the exterior cover40is rotatably attached to the conveyance guide member35and is biased by the torsion spring43is described. However, other biasing member such as a coil spring and a plate spring may be used in place of the torsion spring43. In the case of making the hooking member38engaged with the engaging pin42manually at the time of inserting unit, it may be so constructed that a biasing means is not provided. There is no special limitation on a mounting position of the exterior cover40as long as the member is fixed on the rails30a,30band is withdrawn together with the rails30a,30b. The exterior cover40may be attached to a member other than the conveyance guide member35.

Further, the present invention can be applied not only to the digital composite machine but also to an intermediate transferring color image forming apparatus in which toner images of respective colors are transferred on a recording sheet at one time after the color images are successively superimposed on a transferring belt. Furthermore, the present invention can be certainly applied to other types of imaging forming apparatuses such as an analog copying machine, a facsimile machine and a laser printer. In the intermediate transferring color image forming apparatus, it may be so constructed that the intermediate transferring roller is withdrawn in a sheet conveyance direction solely or with the fixing unit15.

As described above, the image forming apparatus according to the present invention includes: a main body; a unit withdrawably mounted in the main body; an exterior cover attached on a front face of the unit; a rail carrying the unit, the rail being withdrawable outwardly from the main body; a rail guide member for supporting the rail slidably; a locking mechanism for restricting movement of the unit and the rail; and a releasing mechanism for releasing the restriction of the locking mechanism, wherein the exterior cover is operable to actuate the releasing mechanism and serves as a handle for the unit.

Accordingly, an image forming apparatus in which a withdrawing operation of the unit can be operated without operating an operation lever and the like. Further, there is no necessity to provide an operation lever and the like for releasing the restriction of the locking mechanism. Consequently, number of components of the locking mechanism can be reduced and a space can be saved so that the image forming apparatus becomes compact and good in design.

In the above described construction, it is preferable that: the exterior cover is shiftable over a first posture and a second posture different from the first posture against the unit; and the locking mechanism includes a hooking member projecting on an inner surface of the exterior cover and an engagement member provided in the main body, the engagement member being engageable with the hooking member when the exterior cover is in the first posture and disengeagable from the engagement member when the exterior cover is in the second posture.

According to this construction, engagement and disengagement of the hooking member with respect to the engagement member can be performed by changing the posture of the exterior cover.

Accordingly, an image forming apparatus having an exterior cover serving as a handle and an operation lever of a locking mechanism can be realized with a simple construction.

In this case, it is preferable that the exterior cover is supported rotatably against the unit and that the exterior cover is not rotated against the unit substantially in the first posture and is rotated a predetermined angle against the unit in the second posture.

According to this construction, the changing of the posture can be easily made by rotating the exterior cover so that an operability can be improved.

Furthermore, it is preferable that a biasing member which urges the exterior cover in such a direction that the hooking member engages with the engagement member. Accordingly, the locking mechanism can be automatically actuated at the time of inserting the unit so that an operability of insertion is also improved.

Further, if a fixing unit is made the withdrawable unit, a withdrawing or inserting operation of the fixing unit can be made more easily at the time of treating jamming occurred in vicinity of the fixing unit or at the time of replacing the fixing unit.

This application is based on patent application No. 2005-220016 filed in Japan, the contents of which are hereby incorporated by references.