Sheet feed device and image forming apparatus

The present invention relates to a sheet feed device comprising a door for supporting one of the rollers of a feed roller pair for feeding a sheet, mounted on the apparatus main body so as to be opened or closed on the one end part side in the roller pair axis direction such that the one roller is pressured against the other roller of the feed roller pair provided in the apparatus main body at the time the door is closed, comprising: an outer door supported rotatably on the apparatus main body on the one side end part side in the feed roller pair axis direction; an inner door for supporting one of the rollers of the feed roller pair, supported rotatably with respect to the outer door on the one side end part side in the one roller axis direction. The one roller of the feed roller pair is separated with respect to the other roller at the time of opening the outer door, and thereafter the inner door is rotated while maintaining the angle with respect to the outer door according to the rotation of the outer door.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet feed device for clamping and feeding a sheet, such as a sheet feed device used for an image forming apparatus such as a copying machine and a laser beam printer.

2. Description of the Related Art

Conventionally, the image forming apparatus such as a copying machine and a laser beam printer include the configuration having a door to be opened or closed with respect to the apparatus main body at the time of for example the paper jamming process. In order to facilitate the paper jamming process, there is a configuration of opening the sheet feeding path (sheet clamping) by separating a feed roller pair for clamping and feeding the sheet according to the door opening and closing operation, that is, by separating the rollers comprising the roller pair.

As to the configuration of the door to be opened or closed, for example, one to be opened or closed around the lower side of the door comprising the apparatus side surface exterior as the rotation center, one to be slid and moved in the right and left direction as it is (substantially parallel to the apparatus installation surface), or the like can be presented. For preventing damage of the feed roller pair to be moved away at the time of releasing clamping of the sheet as mentioned above, a configuration of opening or closing by moving parallel the other roller with respect to one roller in the roller axis direction is preferable.

For example, as shown inFIG. 12, there is one having one roller5out of a feed roller pair5,10provided between an apparatus main body front side plate8and an apparatus main body rear side plate9disposed on the side of a door91to be opened or closed with respect to the apparatus main body. The one roller5provided on the door91side is forced to the other roller10side on the apparatus main body side by pressure springs4a,4bfor obtaining the feeding force. Therefore, in a state with the door91opened, the roller5on the door91side is disposed at a position with a stopper part3a(3b) of a roller bearing3for supporting the one roller5and a stopper part51a(51b) of a door51are engaged according to the urging force of the pressure springs4a,4b. According to the configuration, since the one roller5is pulled out substantially parallel to the other roller10according to the opening and closing operation (slide movement) of the door91at the time of the paper jamming process, the paper jamming process can be executed by releasing the clamping state of the feed roller pair5,10without damaging the rollers5,10.

However, in the case the rotation shaft of the door to be opened or closed with respect to the apparatus main body is provided on the lower side of the door, or in the case the door is slid and moved in the right and left direction in the above-mentioned conventional examples, unless the grip for opening or closing the door is disposed in the substantial center of the door, the opening and closing operation cannot be executed smoothly, and thus a problem of the poor operability is involved.

Furthermore, in the case the rotation axis of the door is provided in the lower side of the door, at the time of opening or closing the door, the user should open the door while supporting the same with the hands, and a problem of the poor operability is involved.

Moreover, in the case the door is slid and moved in the right and left direction as it is, the door can hardly be slid and moved smoothly unless the front and rear sides of the door are well balanced (in the direction substantially orthogonal to the moving direction), and thus a problem of the poor operability is involved. Furthermore, for sliding and moving the door easily and smoothly, a problem of the complication of the mechanism for sliding and moving the door is involved.

Therefore, in order to improve the user operability, as shown inFIG. 11, a configuration of providing the door51provided with the rotation axis51aon the apparatus deeper side for opening and closing the door51from the apparatus front side to the apparatus deeper side, can be considered. However, in the case of the configuration of opening and closing by separating the feed roller pair5,10as in the above-mentioned conventional example, using the door51shown inFIG. 11, the following problem is involved.

As shown inFIG. 11, the one roller5provided on the door51side out of the feed roller pair5,10provided between the apparatus main body front side plate8and the apparatus main body rear side plate9is forced to the other roller10side on the apparatus main body side by the pressure springs4a,4bfor obtaining the feeding force. Therefore, in a state with the door51opened, the roller5on the door51side is disposed at a position with the stopper part3a(3b) of the roller bearing3for supporting the one roller5and the stopper part51a(51b) of the door51engaged by the urging force of the pressure springs4a,4b. Therefore, by closing the door51in this state, since the deeper side end part5aof the roller5on the door51side is contacted with the circumferential surface of the roller10on the apparatus main body side during the closing operation, there is the risk of damaging the circumferential surface of the roller10on the apparatus main body side or the deeper side end part5aof the roller5on the door51side.

For example, in the case the other roller10of the feed roller pair is an intermediate transfer belt for bearing a toner image (the reference numeral152inFIG. 11andFIG. 12), a photosensitive drum, or the like, a problem of causing the image deterioration is involved. Or in the case the deeper side end part of the one roller5of the feed roller pair is a gear for transmitting the driving force, there is the risk of causing breakage of the members.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a sheet feed device and an image forming apparatus with a good user operability even in the case of separating and releasing a feed roller pair by opening a door from the front side to the deeper side with the rotation axis provided on the deeper side, capable of preventing damage of the members such as the feed roller pair according to the door opening and closing operation.

Still another object of the present invention will become apparent while reading the following detailed explanation with reference to the accompanied drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, with reference to the drawings, preferable embodiments of the present invention will be explained in detail. However, the size of the constituent parts, the material, the shape, the relative arrangement thereof, or the like described in the following embodiments can be optionally changed according to the configuration of the apparatus to adopt the present invention and the various conditions so that the scope of the present invention is not limited thereby unless there is specific description.

First, with reference toFIG. 2, an image forming apparatus using the sheet feed device according to this embodiment of the present invention will be explained.FIG. 2is a cross-sectional view of the image forming apparatus. An example of a copying machine is shown herein.

InFIG. 2, the reference numeral101denotes an image forming apparatus main body, and an original base plate102comprising a transparent glass plate is fixedly provided in the upper part of the image forming apparatus main body101. The reference numeral103denotes an original pressing plate, for pressing and fixing an original100placed at a predetermined position of the original base plate102with the image surface disposed downward. An optical system comprising a lamp104for illuminating the original100, and reflecting mirrors105,106,107for guiding the light image of the illuminated original100to an image processing unit108is provided below the original base plate102. The lamp104and the reflecting mirrors105,106,107are moved by a predetermined rate while scanning the original100.

An image forming part115comprises a photosensitive drum112, a charge roller106for evenly charging the surface of the photosensitive drum112, a laser unit109for forming a latent image on the photosensitive drum112by irradiating an image light, a rotary developing unit151for forming a toner image on the photosensitive drum112, an intermediate transfer belt152in which the toner image developed on the surface of the photosensitive drum112is transferred, a transfer inner roller10for collectively transferring the toner image on the intermediate transfer belt152to a sheet S, a cleaner126for removing the toner remaining on the photosensitive drum112after transferring the toner image, or the like. The photosensitive drum112develops an electrostatic latent image formed by a light image irradiated from the laser unit109on the surface of the photosensitive drum112charged by the charge roller160and successively transfer and superimpose the same onto the intermediate transfer belt152. The toner image on the intermediate transfer belt152is transferred onto the sheet S collectively by the transfer inner roller10of the secondary transfer part. The sheet S is supplied selectively one by one from a sheet cassette127by a feeding part128.

A fixing device122for fixing a toner image on the sheet S being fed as a permanent image, and a discharge roller pair124for discharging the sheet S with the toner image fixed by the fixing device122from the image forming apparatus main body101are provided successively on the downstream side of the image forming part115. A discharge part125for receiving the sheet S discharged by the discharge roller pair124is provided outside the image forming apparatus main body101.

Furthermore, the image forming apparatus according to this embodiment comprises a secondary transfer part having a transfer outer roller5and a transfer inner roller10as the feed roller pair for clamping and feeding the sheet, and a sheet feed device having doors1,2having the rotation axis on the apparatus main body deeper side, for supporting the one transfer outer roller5of the secondary transfer part.

As shown inFIGS. 1,3,4and5, the doors1,2provide the two door configuration of the outer door1having a hinge shaft1ato be the rotation axis of the entire door on the apparatus main body101deeper side, and the inner door2having the hinge shaft2con the outer door1deeper side to rotate with respect to the outer door1. Then, in the case of opening or closing the doors1,2, first by gradually opening the inner door2about the outer door hinge shaft1awith respect to the outer door1, the one roller5of the feed roller pair5,10provided to the inner door2is moved substantially parallel in the vicinity of the separation part in the axis direction with respect to the other roller10. Then, after moving the one roller5substantially parallel in the vicinity of the separation part in the axis direction with respect to the other roller10, that is, after opening the outer door1with respect to the inner door2by a certain angle, the inner door2is rotated while maintaining the angle (the above-mentioned certain angle) with respect to the outer door1according to the further rotation of the outer door1. It is possible that the one roller5is separated by slightly moving obliquely with respect to the other roller10for separating the roller pair without damaging the roller pair by the rotation as in the conventional example.

Hereinafter, with reference toFIGS. 1,3,4and5, the characteristic parts will be explained in detail.FIGS. 1,3,4and5are schematic drawings of the door and the feed system in the vicinity of the door of the sheet feed device in the image forming apparatus according to this embodiment, viewed from above.FIG. 3is a drawing with the door in a closed state, andFIGS. 4,1,5are drawings in the halfway of the door opening and closing operation.

The ordinary state is the door closed state shown inFIG. 3. The transfer inner roller10constituting the secondary transfer part as the feed roller pair is disposed between the apparatus main body front side plate8and the apparatus main body rear side plate9so that the transfer inner roller10is rotated following the intermediate transfer belt152to be driven by an unshown driving means.

The outer door1is to be rotated with respect to the apparatus main body rear side plate9by the outer door hinge shaft1aas the rotation axis of the entire door, and the apparatus main body front side as the free end is engaged with the apparatus main body front side plate8by an unshown lock mechanism. The inner door2is rotated with respect to the outer door1by the inner door hinge shaft2, and it positions the door and stop the rotation thereof by receiving the positioning part1cprovided on the free end side of the outer door1at the positioning part2eprovided on the free end side. Moreover, the inner door2has the transfer outer roller5constituting the secondary transfer part as the feed roller pair such that the transfer outer roller is forced by the pressure springs4a,4bso as to press the transfer inner roller10. According to the pressure, the sheet S is clamped and fed by the transfer roller pair5,10via the intermediate transfer belt152. Moreover, the gap between the outer door1and the inner door2constituting the door forms a feeding path for guiding the sheet (seeFIG. 1).

Next, the movement of the above-mentioned constituent elements at the time of opening the door will be explained. As shown in the state inFIG. 3toFIG. 4, in the case the outer door1is opened to the arrow C direction, the inner door2is to be opened in the arrow D direction by an inner door opening spring7with the end parts7a,7bengaged with the doors1,2respectively. However, since the transfer outer roller5on the inner door2side is pressured against the transfer inner roller10on the apparatus main body side by the pressure springs4a,4b, the inner door2has the apparatus deeper side opened in the arrow E direction with the front side end part5bof the transfer outer roller5as the substantial fulcrum. As a result, the transfer outer roller5on the inner door2side is opened substantially parallel in the axis direction with respect to the transfer inner roller10on the apparatus main body side.

Then, as shown inFIG. 1, in a state with the transfer outer roller5on the door side separated from the transfer inner roller10on the apparatus main body side, the roller5on the inner door2side is disposed at a position with the stopper parts3a,3bof the roller bearing3for supporting the one transfer outer roller5and the stopper parts2a,2bof the inner door2engaged according to the urging force of the pressure springs4a,4b. As it is understood from the state shown inFIG. 1, according to the configuration of this embodiment, the transfer outer roller5on the door side is opened substantially parallel in the axis direction with respect to the transfer inner roller10on the apparatus main body side.

Moreover, as shown inFIG. 1, a lock mechanism for locking the inner door2with respect to the outer door1in a state with the opening angle β of the outer door1and the inner door2satisfy the relationship with respect to the angle α formed by the straight line linking the outer door hinge shaft1acenter and the inner door hinge shaft2ccenter and the straight line from the outer door hinge shaft1acenter perpendicular to the outer door1of β≧α (certain angle or more), is provided. That is, in the case the opening angle β of the outer door1and the inner door2satisfies the above-mentioned relationship, the opening stopper member6mounted rotatably on the stopper axis2dof the inner door2is rotated in the arrow F direction by the urging force of an unshown pressuring member so that the engaging part6aof the stopper member6is engaged with the engaging projection1bon the outer door1side, and the inner door2is in the locked state with respect to the rotating outer door1. From the locked state shown inFIG. 1, the inner door2is opened following the outer door1as shown inFIG. 5in a state locked with the outer door1. Thereby, according to this embodiment, the roller pair5,10to have the clamped state opened according to the door opening operation is rotated about the door axis as shown inFIG. 5after separated substantially parallel in the axis direction as shown inFIG. 1.

At the time of closing the door, it is operated in the opposite order (FIG.5→FIG.1→FIG.4→FIG. 3) with respect to the above-mentioned order (FIG.3→FIG.4→FIG.1→FIG. 5). That is, according to this embodiment, in the order opposite to the door opening operation, since the roller pair5,10to be contacted in the clamped state according to the door closing operation is in a state separated substantially parallel in the axis direction as shown inFIG. 1before releasing the engagement of the stopper member6on the inner door2side and the engaging projection1bon the outer door1side, even in the case the door is rotated from this state to the state shown inFIG. 4(engagement released state), the roller pair5,10is contacted with the substantially parallel state in the axis direction maintained.

As mentioned above, according to this embodiment, even in the case of separating and opening the feed roller pair by opening the door from the front side to the deeper side with the rotation axis provided on the deeper side, by gradually opening the inner door with respect to the outer door1about the outer door hinge shaft1a, since one of the roller5of the feed roller pair5,10is moved substantially parallel with respect to the other roller10in the axis direction, the user operability is good. Furthermore, since the feed roller pair5,10is opened or closed substantially parallel in the axis direction, damage of the feed roller pair accompanied by the door opening or closing operation can be prevented.

Although the configuration of supporting or releasing the support of the opening angle β of the outer door1and the inner door2is provided in the lock mechanism shown inFIGS. 1 and 2by engaging or releasing the engagement of the rotatable stopper member6pressured in the arrow F direction on the inner door2side and the engaging projection1bon the outer door1side, the lock mechanism of the doors1,2according to the present invention is not limited thereto, and it may be provided as follows.

As shown inFIGS. 6,7, the lock mechanism comprises a first link21provided rotatably on a shaft2dof the inner door2, and a second link22provided rotatably on a shaft21bof the first link21and a shaft1dof the outer door1. At the time of opening the outer door1with respect to the inner door2from the state shown inFIG. 6, the links21,22are opened in the arrow G direction shown inFIG. 7with the shaft21bas the fulcrum by a pressure member such as an unshown torsion coil spring, or the like so that the inner door2is in a state locked with the rotating outer door1according to the engagement of the stopper part21aof the first link21and the second link22.

Since the other schematic configuration of the apparatus is same as that shown inFIGS. 1 and 2, the same reference numerals are applied on the members having the same function, and detailed explanation is omitted here.

According to the lock mechanism, at the time of separating and opening the feed roller pair by opening the doors from the front side to the deeper side with the rotation shaft provided on the deeper side, the user operability is good. Furthermore, since the feed roller pair5,10is opened or closed substantially parallel in the axis direction, damage of the feed roller pair accompanied by the door opening or closing operation can be prevented.

Although an example of the transfer roller pair5,10constituting the secondary transfer part is explained as the feed roller pair for clamping or releasing the clamp according to the opening or closing operation of the doors1,2in the configuration shown inFIGS. 1 and 2, the present invention is not limited thereto, and it can be provided as follows.

In an image forming apparatus for transferring a toner image formed on the photosensitive drum31as the image bearing member in an image forming part onto a sheet fed from a feeding part by the transfer roller32, as shown inFIG. 8, an example of the feed roller pair for clamping or releasing the clamp accompanied by the opening or closing operation of the doors1,2is shown as a roller pair31,32comprising the photosensitive drum31and the transfer roller32. In this case, as shown inFIG. 8, the transfer roller32provided on the door side is opened or closed substantially parallel in the axis direction with respect to the photosensitive drum31on the apparatus main body side accompanied by the opening or closing operation of the doors1,2.

Either in the case of this configuration, or in the case of separating and opening the feed roller pair by opening the doors from the front side to the deeper side with the rotation axis provided on the deeper side, the user operability is good. Furthermore, since the feed roller pair31,32is opened substantially parallel in the axis direction, damage of the feed roller pair accompanied by the door opening or closing operation can be prevented.

Furthermore, the next configuration can also be adopted. As the feed roller pair for clamping or releasing the clamp according to the opening or closing operation of the doors1,2, a roller pair comprising each of the rollers of the feed roller pair to be driven by a gear can be used.

Here, a registration roller pair41,44is shown as an example. As shown inFIG. 9, the registration roller pair41,44comprises a registration roller41disposed on the apparatus main body side and a registration roller44disposed on the door side. The main body side registration roller41is rotated and driven by an unshown driving source. Thereby, the drive is transmitted from the main body side registration roller gear42engaged with the deeper side end part of the main body side registration roller41to the door side registration roller gear43engaged with the deeper side end part of the door side registration roller44so that the door side registration roller44is rotated and driven.

Since the other schematic configuration of the apparatus is same as that shown inFIGS. 1 and 2, the same reference numerals are applied on the members having the same function and detailed explanation is omitted here.

According to the registration roller pair of the configuration, by disposing the registration roller44of the registration roller pair on the inner door2of the doors1,2shown inFIGS. 1 and 2, the user operability is good. Furthermore, since the feed roller pair41,44is opened or closed substantially parallel in the axis direction, damage of the feed roller pair accompanied by the door opening or closing operation can be prevented.

Although an example of one pair of the feed roller pair for clamping or releasing the clamp according to the opening or closing operation of the doors comprising the outer door and the inner door in a sheet feed device or an image forming apparatus is explained in this embodiment, the present invention is not limited thereto, and a plurality of the feed roller pairs for clamping or releasing the clamp according to the opening or closing operation of the doors comprising the outer door and the inner door in a sheet feed device or an image forming apparatus can be provided.

For example, both the transfer roller pair5,10as the feed roller pair and the registration roller pair41,44as the feed roller pair may be opened or closed substantially parallel in the axis direction according to the opening or closing operation of the doors comprising the outer door1and the inner door2. According to this configuration, not only the same effect as in the above-mentioned embodiment can be obtained but also the user operability can further be improved since the feeding path can be opened in a wider range.

FIG. 10is a schematic diagram showing an example of the present invention adopted in a sheet feed device in an image forming apparatus, viewed from the front side.

Out of the doors comprising the outer door1and the inner door2, the inner door2comprises a first feed part201for feeding a sheet with respect to the apparatus main body, and a second feed part202for feeding the sheet with respect to an outer door1. The first feed part201and the second feed part202constituting the inner door2have the float configuration with springs207,208provided therebetween. In the figure, the reference numerals201a,201bdenote limiting members for limiting separation of the feed parts201,202by more than a predetermined amount by the springs207,208.

In the first feed part201disposed on the apparatus main body side of the inner door2, one of the transfer outer roller5constituting the secondary transfer part as the feed roller pair is forced by a spring209so as to be supported rotatably by a supporting member217swayable about the fulcrum217a. Furthermore, one of the registration roller44of the registration roller pair as the feed roller pair is forced by a spring211so as to be supported rotatably by a bearing210movable parallel by an unshown slide mechanism. Moreover, the first feed part201is positioned by positioning parts201c,201dprovided on the first feed part201side and positioning parts203,204aprovided on the apparatus main body side.

Moreover, in the figure, the reference numeral201edenotes a feed guide provided in the inner door2for forming a feeding path for guiding a sheet on the first feed part side of the inner door2. The reference numerals204,212denote feed guides provided on the apparatus main body side for forming the feeding path for guiding a sheet together with the feed guide on the first feed part side of the inner door2.

In contrast, in the second feed part202disposed on the outer door side of the inner door2, one of a feed roller214of a feed roller pair213,214for feeding a sheet in the feeding path with respect to the outer door1is forced by a spring216so as to be supported rotatably by a bearing215movable parallel by an unshown slide mechanism. Moreover, the second feed part202is positioned by positioning parts202a,202bprovided on the second feed part202side and outer door positioning parts205a,206aprovided on the outer door1side.

Moreover, in the figure, the reference numerals205,206denote feed guides provided in the outer door1for forming a feeding path for guiding a sheet together with the feed guide formed by the second feed part202of the inner door2.

Since the other schematic configuration of the apparatus is same as that shown inFIGS. 1 and 2, the same reference numerals are applied on the members having the same functions and detailed explanation is omitted here.

Accordingly, in the apparatus for separating and opening the feed roller pair by opening the door from the front side to the deeper side with the rotation axis provided on the deeper side, since a plurality of the feeding paths disposed between the door and the apparatus main body can be opened or closed, and the feed parts (a plurality of the feed roller pairs) for clamping and feeding the sheet in the feeding paths can be opened or closed substantially parallel in the axis direction, not only the damage of the feed roller pair accompanied by the door opening or closing operation can be prevented but also the user operability can further be improved.

Since the second feed part disposed between the outer door1and the inner door2is the feed roller pair213,214and the offset amount of the roller with respect to the normal direction of the roller and the hinge shaft in the roller axis direction is small, the roller can hardly be flawed, and even in the case it is flawed, since the roller pair is the feed roller pair as mentioned above, the feed failure cannot be generated by the feeding force deterioration derived from several flaws.

Although the number of the developing units provided in the rotary developing unit as the rotation type developing unit has not been described specifically in the above-mentioned embodiment, the number of use is not limited, and it can be set optionally as needed.

Moreover, although an example of a copying machine as the image forming apparatus is shown in the embodiment, the present invention is not limited thereto. For example, other image forming apparatus such as a printer, and a facsimile machine, image forming apparatus using a transfer drum instead of a transfer belt as the intermediate transfer member for transferring and superimposing toner images of each color successively on the transfer drum, and transferring the transferred toner images collectively onto a transfer medium, or image forming apparatus using a transfer material bearing member such as a transfer feed belt, and a transfer drum for transferring and superimposing toner images of each color successively on the transfer member bore on the transfer material bearing member may be used as well. By adopting the present invention to the sheet feed device used for the image forming apparatus, the same effect can be obtained.

Moreover, although an example of a sheet feed device for feeding a sheet such as a recording paper as the recording subject has been described in the embodiment, the present invention is not limited thereto. For example, by adopting the present invention to the sheet feed unit for feeding a sheet such as an original as the reading subject, the same effect can be obtained.

Moreover, although an example of the electrophotographic system as the recording system has been described in the embodiment, it is not limited thereto. For example, another recording system such as the ink jet system can be used as well.