Sheet discharge device and image forming apparatus

The present application claims the benefit of priority under 35 U.S.C. §119 from Japanese Patent Application No. JP 2013-132961, filed on Jun. 25, 2013. The entire contents of Japanese Patent Application No. JP 2013-132961 are incorporated herein by reference.

I. Field of the Invention

Exemplary aspects of the present application generally relate to a sheet discharge device and an image forming apparatus.

II. Background Art

Conventionally, in an image forming apparatus such as a copier, a facsimile, a printer, and a printing machine, or the like, a copied material or a printed material is generated by heating and fixing an unfixed image, which is transferred and is supported on a recording medium.

On the other hand, a sheet with a fixed image often has a curl due to heating and pressure during fixing. Therefore a failure in conveyance of a sheet may occur when a curled sheet is conveyed after fixing the sheet. Conventionally, to prevent the failure in conveyance of a sheet due to a sheet jam, a sheet discharged after fixing is curled in an inverse direction of a curl. As such, the curled sheet is corrected.

JP 2009-113929 discloses a structure to correct a curl in which each of a facing roller pair has a different hardness and a rotating speed of the roller pair is changed according to a thickness and kind of a sheet.

JP 2007-217187 discloses a structure to correct a curl of a cardboard sheet or a thin sheet in which a guide plate to be curved in an inverse direction of a curl is arranged at a position just after the sheet passes a fixing device, and an angle of the plate is arranged so that a curl of the sheet is corrected.

JP 2002-12336 discloses that a conveying roller is separated from a counter roller to the conveying roller so that it is possible to remove a jammed sheet from those rollers.

However, the curl correcting mechanism which JP 2009-113929 and JP 2007-217187 disclose is arranged at a position just after where a sheet passes a fixing device. In this case, it is not considered that the sheet that has passed the curl correcting mechanism is curled again according to a shape of a conveying pass, such as an inverting pass. In other words, if a curl of the sheet corrected by the curl correcting mechanism is not completely removed at the fixing time, the sheet might be curled again in a process where the sheet moves in a curved pass.

On the other hand, in the case of JP 2002-12336, a special structure in which a roller pair is operated to contact and separate from each other is required, and this structure is not expected to remove a jam with a simple operation.

In light of the problems and circumstances described above, a main object of the present application is to provide a sheet discharge device and an image forming apparatus in which a conveying pass is certainly opened and is exposed from an outside. As such, a jam can be removed easily.

According to an embodiment of the present application, a sheet discharge device includes: a fixing device that fixes a sheet, a curl correcting device that corrects a curl of the fixed sheet, a first guiding member that guides the fixed sheet in a sheet discharging direction, a second guiding member that guides the fixed sheet in the sheet discharging direction and is arranged on a side opposite to the first guiding member, a support part that rotatably supports the first guiding member, and an engaging part that engages with the support part. The curl correcting device includes a correcting roller that is attached to the first guiding member. The engaging part includes a hole including an oblong shape so that the first guiding member is movable apart from the second guiding member.

FIG. 1 is a diagram showing a schematic configuration of the image forming apparatus including a sheet discharge device, which shows an illustrative embodiment of the present application;

FIG. 2 is an external view of the sheet discharge device shown in FIG. 1 ;

FIG. 3 is a diagram illustrating an internal configuration of the sheet discharge device, which shows an illustrative embodiment of the present application;

FIG. 4 is an external view showing a state in which a part of the sheet discharge device shown in FIG. 2 is opened;

FIG. 5 is a diagram illustrating a first operation mode of the sheet discharge device shown in FIG. 2 ;

FIG. 6 is a diagram showing a second operation mode changed from the first operation mode shown in FIG. 5 ;

FIG. 7 is a diagram showing a third operation mode changed from the second operation mode shown in FIG. 6 ;

FIG. 8 is a diagram illustrating an example of an engaging configuration included in the sheet discharge device shown in FIG. 2 ;

FIG. 9 is a perspective view illustrating an engaging configuration included in the sheet discharge device shown in FIG. 2 ;

FIG. 10 is a diagram illustrating another example of the engaging configuration shown in FIG. 8 ; and

FIG. 11 is a diagram illustrating another example of the configuration shown in FIG. 4 .

Illustrative embodiments of the present application are described in detail with reference to the plural drawings.

In FIG. 1 , an image forming apparatus 1 includes a feeding device 6 for feeding a sheet, an image forming device 12 for forming an image on the sheet fed by the feeding device 6 , a fixing device 8 for fixing an unfixed image which is formed on the sheet by the image forming device 12 , and a discharge roller pair 9 for discharging the fixed sheet to a discharge tray 1 A 1 .

The image forming device 12 includes a photoreceptor 2 for forming an electrostatic latent image on the outer surface according to image information, a developing device 4 for supplying toner to the photoreceptor 2 so that a toner image is formed on the photoreceptor 2 , and a transfer device 7 for transferring the toner image on the photoreceptor 2 to the sheet fed by the feeding device 6 , as an unfixed image.

The fixing device 8 includes a heating roller 8 A and a pressure roller 8 B which melt and permeate a toner image on a sheet so that the toner image is fixed on the sheet.

The image forming apparatus 1 includes a configuration for forming an image on one side and on both sides of a sheet. The configuration includes a discharge pass P 1 for discharging a sheet which has passed the fixing device 8 to the discharge tray 1 A 1 , and a switchback pass P 2 for reversing a sheet.

A pass switch part 10 switches conveying directions of the sheet fixed by the fixing device 8 . In a state in which the pass switch part 10 is shown by a solid line in FIG. 1 , the fixed sheet is guided to a contacting position between a discharge driving roller 9 A and a discharge driven roller 9 B. In this state, the fixed sheet is discharged directly to the discharge tray 1 A 1 .

On the other hand, in a state in which the pass switch part 10 is shown by a dashed line in FIG. 1 , the fixed sheet is guided to a contacting position between the discharge driving roller 9 A and a discharge driven roller 9 C. In this state, once the fixed sheet is conveyed a predetermined amount by the discharge roller pair 9 in a discharging direction to the discharge tray 1 A 1 , next, the fixed sheet is conveyed again to the switchback pass P 2 by rotating the discharge roller pair 9 in a reverse direction.

In FIG. 2 , a sheet discharge device 100 includes the fixing device 8 , the discharge pass P 1 , and the switchback pass P 2 . One surface of the switchback pass P 2 is a pass surface 101 included in the sheet discharge device 100 . As such, an apparatus body 1 A can be made compact.

The pass surface 101 includes a handle 102 which is used when the sheet discharge device 100 is attached to and removed from the apparatus body 1 A.

In FIG. 1 , the apparatus body 1 A includes an openable cover 1 A 2 so that the sheet discharge device 100 can be attached to and removed from the apparatus body 1 A.

In FIG. 3 , a fixing device discharging roller pair 103 A, 103 B for discharging a sheet to the discharge roller pair 9 is arranged in the discharge pass P 1 .

In a configuration of the fixing device discharging roller pair 103 A, 103 B, the roller of the fixing device discharging roller pair 103 A, 103 B which contacts a surface opposite to a curled surface of the sheet, presses the other roller of the fixing device discharging roller pair 103 A, 103 B, so that the curl of the sheet is corrected.

In the sheet discharge device 100 shown in FIG. 3 , a curl of the sheet that has passed the fixing device 8 is corrected by the fixing device discharging roller pair 103 A, 103 B, and a driven roller 105 .

In FIG. 3 , a sheet discharged from the fixing device 8 moves along a guide member 104 .

An arrow shown with a solid line in FIG. 3 shows a direction in which a sheet discharged from the fixing device 8 moves to the fixing device discharging roller pair 103 A, 103 B, without being guided by the driven roller 105 .

In an embodiment of the present application, an arrow shown with a dashed line in FIG. 3 , shows a direction in which a sheet discharged from the fixing device 8 moves to the fixing device discharging roller pair 103 A, 103 B, while be guided by the driven roller 105 . In other words, when the sheet discharged from the fixing device 8 reaches the driven roller 105 , the direction in which the sheet moves changes to a direction apart from the guide member 104 .

In a state when the sheet is held between the fixing device discharging roller 103 A and the fixing device discharging roller 103 B, the sheet is pressed in the direction apart from the guide member 104 by the driven roller 105 . In addition, the curl of the sheet is corrected with the fixing device discharging roller pair 103 A, 103 B.

As such, an angle that the sheet is wound around the driven roller 105 can be made smaller than the angle without the fixing device discharging roller pair 103 A, 103 B. Therefore, this configuration prevents formation of a new curl in a reverse direction due to correction of the original curl of the sheet. In addition, the configuration prevents formation of the original curl again due to a shape restoring force of the sheet. Furthermore, the driven roller 105 prevents damaging an image on the sheet.

On the other hand, a discharge pass surface P 1 A is arranged facing a side of a sheet that is an image formed surface of the sheet discharged from the fixing device 8 , and is attached to a guide member 106 . The driven roller 105 is attached to the guide member 106 .

In FIG. 3 , a support shaft 107 is arranged at the sheet discharge device 100 . An engaging part 108 has a hole of an oblong shape formed at the guide member 106 , and is engaged with the support shaft 107 . As such, the guide member 106 can rotate around the support shaft 107 in a direction shown with an arrow X in FIG. 5 . In addition, the guide member 106 can move along the hole of oblong shape in the engaging part 108 in a direction shown with an arrow Y in FIG. 6 .

In FIG. 5 , when the guide member 106 is rotated in the direction shown with the arrow X, at first, the driven roller 105 contacts a pass surface P 1 B. In addition, the guide member 106 moves along the oblong hole shape of the engaging part 108 in a direction shown with an arrow Y in FIG. 6 . Furthermore, when the guide member 106 continues being rotated while the driven roller 105 is apart from the pass surface P 1 B, the discharge pass P 1 is finally in an opened state as shown in FIG. 7 .

The above configuration enables an operation to remove a jammed sheet speedily and to miniaturize the sheet discharge device, regardless of the fact that the sheet discharge device includes the curl correcting mechanism.

In FIG. 8 and FIG. 9 , a holding member 200 includes a projection portion 201 and a concave portion 202 . The projection portion 201 is arranged at the guide member 106 and the concave portion 202 is arranged at the sheet discharge device 100 . The projection portion 201 is engaged with the concave portion 202 when the guide member 106 is closed, as shown in FIG. 8 . The engaged position is decided so that the driven roller 105 can correct the curl of the sheet. As such, this configuration prevents the guide member 106 from moving in a direction of an arrow Z, shown in FIG. 8 , regardless of the hole of oblong shape in the engaging part 108 .

On the other hand, another configuration may be formed with a projection portion 201 ′ arranged at the sheet discharge device 100 and a concave portion 202 ′ arranged at the guide member 106 , as shown in FIG. 10 .

In one example, a handle 203 shown in FIG. 8 to FIG. 10 is used when a user opens the guide member 106 .

On the other hand, another configuration may be formed with the support shaft 107 arranged at a guide member 106 A and the engaging part 108 arranged at the sheet discharge device 100 , as shown in FIG. 11 .