JPH0958899A - Sheet conveying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set tolerance to a curl quantity of a sheet by disposing a sheet face height detecting means away from a feeding member in a vertical direction to a sheet conveying direction within the plane of sheets stacked on a stacking member. SOLUTION: When a sheet conveying device starts its action, the uppermost face of sheets 5 is moved up by a sheet elevating tray 30, and a sheet contact member 20 comes in contact and moves together. A sheet face sensor 21 detects the movement of the sheet contact member 20 and recognizes the height of the sheet 5 at a part in contact with the sheet contact member 20. When a height of the sheet 5 reaches a feeding standard position H1, driving transmission to the sheet elevating tray 30 is stopped, and a pickup roller 10 is lowered onto the sheet 5 and also rotated to deliver the sheet 5. A tolerance of a curl quantity per a length of detection space L1 so as to be stably conveyable by the sheet conveying device is set to a distance from the standard position H1 to a lower limit position H2. The sheet is not therefore conveyed in the case of the curl quantity exceeding the tolerance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus having a sheet lifting mechanism provided in a printer or a copying machine,
Also, the present invention relates to an image forming apparatus including the sheet conveying device.

[0002]

2. Description of the Related Art Sheets such as paper are mainly deformed due to moisture absorption, drying, and repetition,
This is called curl. Since the curled sheet has a three-dimensional structure, it is difficult to define the position of the sheet, the sheet is caught when it is sent to the conveying path, and a paper jam occurs in the conveying device. Conventionally, in a sheet conveying device having an automatic lifting mechanism, sheet end restraints are provided at both end positions of the sheet, the curl generated in the sheet is pressed down into a flat surface, and the sheet is further sent to a downstream sheet conveying device and an image forming apparatus. Was there.

A conventional example is shown in FIG. The sheet 53 is stacked on the sheet elevating tray 52 and moved to the feeding area by an elevating mechanism (not shown). At that time, the side surfaces of the sheet elevating tray 52 and the sheet 53 are seat side guides 54a, 54b.
Stipulated by When the sheet 53 reaches the vicinity of the feeding area, the sheet surface contact member 51 provided in the vicinity of the pickup roller 50 contacts the uppermost surface of the sheet 53 and moves together, and the sheet surface contact member 51 is moved. The surface sensor 56 detects the position of the uppermost surface of the sheet 53.

The sheet raising / lowering tray 52 moves based on the information detected by the sheet surface sensor 56, and stops when the uppermost surface of the sheet 53 reaches a predetermined feeding position. At that time, the sheet side guide 54
The sheet edge restraints 55a and 55b fixed to a and 54b are pressed and straightened. When there is an instruction to start transportation, the sheet
53 is sent out by the pickup roller 50, sent to the next pair of separation rollers (not shown), separated, and then conveyed.

[0005]

However, in the prior art, since the curl is suppressed by the fixed sheet edge restraint, the curl amount is increased particularly in the sheet conveying device equipped with a large-capacity sheet stacking device. The conveyance is not stable due to the frictional resistance generated by pressing the curl. Further, even if the curl can be pressed and corrected at the pickup position to be fed, the curl is restored in the downstream sheet conveying apparatus or the image forming apparatus connected to the sheet conveying apparatus, and the There was a high possibility that conveyance defects such as clogging would occur.

[0006]

A typical structure of a sheet conveying apparatus according to the present invention is a sheet conveying apparatus main body, a stacking member on which sheets to be conveyed are stacked, and an elevating mechanism for elevating the stacking member. In a sheet conveying device having a sheet surface height detecting means for detecting the sheet surface height of the sheets stacked on the stacking member, and a feeding member for sending out the sheet, the sheet surface height detecting means comprises: In the plane of the sheets stacked on the stacking member, the sheet is arranged separately from the feeding member in a direction perpendicular to the sheet conveying direction.

Further, in the above-mentioned sheet conveying apparatus, a sheet edge height detecting means which comes into contact with an edge portion of the sheet and is vertically movable is provided, and the sheet surface height detecting means is interlocked with the sheet edge height detecting means. It is characterized in that it can be moved up and down.

Further, the sheet edge height detecting means is provided with a means for detecting that a certain height is reached when the sheet edge height detecting means comes into contact with the sheet and moves upward.

An image forming apparatus according to the present invention includes any one of the above-mentioned sheet conveying devices, and conveys the sheet conveyed by the sheet conveying device further downstream, and conveys by the conveying means. An image forming unit for forming an image on a sheet according to image information.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] A first embodiment of a sheet conveying device and an image forming apparatus including the same according to the present invention will be specifically described with reference to the drawings. 1 is a cross-sectional explanatory view showing an image forming apparatus provided with a sheet conveying device of the present invention, FIG. 2 is a diagram showing a configuration of a sheet elevating mechanism of the sheet conveying device, and FIG. 3 is a layout diagram around a pickup roller.

In FIG. 1, 1 is a sheet conveying device according to the present invention, and 2 is a main body of an electrophotographic image forming apparatus equipped with the sheet conveying device 1. As shown in FIG. 1, the sheet conveying apparatus 1 is arranged below the image forming apparatus main body 2.
The sheet 5 that has been conveyed up and down by the sheet conveyance device 1 is supplied by a pickup roller 10 that is a feeding member,
Further, the sheet 5 is separated by the feed roller 11 and the retard roller 12 so as not to be overlapped and conveyed to the sheet conveying path 6.

The sheet 5 is conveyed by the conveying rollers 13a, 13b, etc. constituting the sheet conveying path 6 and carried into the sheet conveying means in the main body 2 from the side surface of the main body 2. After that, the sheet 5 conveyed by the conveying roller 13c and the registration roller 14 is a process in which an electrophotographic process means such as a photosensitive drum 15 which forms a toner image by light irradiation according to image information from the optical system 7 is formed into a cartridge. The toner image formed on the cartridge and the drum 15 is attached to the sheet 5
An image is formed by an image forming unit including a transfer roller 16 for transferring the image onto the sheet. Next, the image is fixed on the sheet 5 by the thermal fixing device 17, and is discharged onto the discharge tray 19 by the discharge roller 18.

Next, the sheet conveying device 1 will be described.
2 and 3, the sheet conveying apparatus 1 has a sheet elevating tray 30 that is a sheet stacking member that is arranged to be able to move up and down in the body of the sheet conveying apparatus, and is made of a predetermined material such as paper or synthetic resin. The lifted tray 30
After being stacked on the sheet, the sheet raising / lowering tray 30 is configured to be able to automatically move up and down to a height position where the sheet 5 can be fed.

Pulleys 38a and 38b rotatably supported are respectively arranged at predetermined positions on the upper sides of both sides of the storage 31 of the sheet conveying device. Lifting wires 33a and 33b are respectively attached to the pulleys 38a and 38b. Engaged and stretched. Sheet elevating trays 30 are fixed to one ends of the elevating wires 33a and 33b, respectively, and the elevating wires 33a and 33b are configured to stably hold the sheet elevating trays 30 substantially horizontally.

The other ends of the lifting wires 33a and 33b are connected to the lifting wire 33.
It is integrally connected to one end of c, and the lifting wire 33
One end of c is wound around a winding reel 37 fixed to a winding shaft 36 rotatably provided in the storage 31. The winding shaft 36 is connected to the drive shaft of the motor 32 via a driving force transmission mechanism 34 connected by a gear train.

Therefore, when the motor 32 is rotated in a predetermined direction, the take-up reel 37 is rotated through the driving force transmission mechanism 34 and the take-up shaft 36, and the elevating wire 33c is sent out or taken up to take up the sheet elevating tray 30. It can be raised and lowered.

A sheet supply frame 4 arranged at a sheet supply port is provided above the storage box 31, and a pickup roller 10 and a sheet surface sensor 21, which constitutes a sheet surface height detecting means, are provided on the sheet supply frame 4. Also, a sheet presence / absence sensor 24 is provided to detect the absence of the sheet 5 in the sheet lifting tray 30.

A seat surface contact member 20 extends downward from the seat surface sensor 21.
Comes in contact with the uppermost surface of the ascending seat and ascends together. The sheet surface sensor 21 is a photo interrupter and detects the movement of the sheet surface contact member 20 by light transmission and light shielding. By detecting the movement of the sheet surface contact member 20 by the sheet surface sensor 21, the uppermost sheet surface height of the sheets 5 stacked on the sheet elevating tray 30 can be detected.

As shown in FIG. 3, the sheet surface sensor 21 and the sheet surface abutting member 20 are arranged in the sheet conveying direction with respect to the pickup roller 10 in the plane of the sheet 5 stacked on the sheet elevating tray 30. It is arranged at a position distant in the vertical left direction (the left side of FIG. 3 in the present embodiment) with respect to (the front and back direction of the paper surface of FIG. 3).

Here, in FIG. 3, the seat surface contact member 20
Is detected by the sheet surface sensor 21 and the height at which the lifting of the sheet lifting tray 30 is stopped is the standard position H1, and the pickup roller 10 is lowered to separate the sheet 5 from the pair of separating rollers 11, which is the next conveying unit. The lower limit height that can be sent to 12 is indicated by the lower limit position H2. Further, the distance between the pickup roller 10 and the sheet surface abutting member 20 in the direction perpendicular to the sheet conveying direction in the sheet plane is indicated by the detection interval L1.

When the sheet conveying device starts to operate, the uppermost surface of the sheet 5 is raised by the sheet elevating tray 30 and approaches the feeding area, and the sheet abutting member 20 abuts on the uppermost surface of the sheet 5 and the sheet abutting member 20 moves together. Moving. The sheet surface sensor 21 detects the movement of the sheet contact member 20, and recognizes the height of the sheet 5 in the portion in contact with the sheet contact member 20. The height of the sheet 5 recognized by the sheet surface sensor 21 is the standard position H1 for feeding.
When it reaches, the drive transmission to the sheet lifting tray 30 is stopped. When a sheet conveyance command is sent in this state, the pickup roller 10 descends onto the sheet 5 and rotates to send the sheet 5 to the separation roller pair 11 and 12.

The allowable amount of curl per length of the detection interval L1 at which the sheet conveying device can stably convey the sheet is set to the standard position.
Set to the distance from H1 to the lower limit position H2. This allows
As shown in FIG. 3, when the curl amount exceeds the allowable amount of the sheet conveying device, the sheet surface sensor 21 detects the uppermost surface of the sheet 5 and stops the sheet elevating tray 30, but the pickup The roller 10 does not reach the sheet 5 and is therefore not delivered to the transport path. As a result, the curled sheet 5 can be removed from the storage box 31 without being conveyed, and it is possible to prevent a conveyance failure in the downstream conveyance device or the image forming apparatus. Therefore, the maintainability is improved.

Further, in this embodiment, since the pickup portion is configured without providing the sheet edge restraints (55a, 55b in FIG. 8) as explained in the conventional example, the friction between the sheet 5 and the sheet edge restraints is provided. Pickup failure due to

[Second Embodiment] A second embodiment of a sheet conveying device according to the present invention and an image forming apparatus having the same will be described with reference to FIGS. 4 and 5. The same parts as those of the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. FIG. 4 is a layout view around the pickup roller, and FIG. 5 is a perspective view of a sheet surface sensor and a sheet surface contact member.

In this embodiment, seat edge height detecting members 23a, 23b are provided on the seat side guides 35a, 35b for guiding both sides of the seat 5 so as to be vertically movable. The detection members 23a and 23b are used as an index of the height of the end portion of the sheet 5, and the initial position is at the same position as the sheet end restraint 55a in the conventional example, but since it is not fixed, the end portion of the sheet 5 is not fixed. It does not press the curl of the sheet 5 by abutting against the portion and swinging up and down.

From the vicinity of the pickup roller 10,
An interlocking arm 22 is provided in a direction perpendicular to the sheet conveying direction. The end of the interlocking arm 22 on the pickup roller 10 side is rotatably attached to the sheet feeding frame 4 by an interlocking arm support 25 so that it can swing in the vertical plane. At the other end of the interlocking arm 22, a seat edge height detecting member 23a is rotatably supported by a shaft 22b, and the seat edge height detecting member 23a is rotatable relative to the interlocking arm 22 from the horizontal direction upward. It is installed. Further, the seat edge height detecting member 23a is normally urged downward by an elastic member 24 provided on the interlocking arm 22 and kept horizontal with respect to the interlocking arm 22.

An interlocking arm stop member 28 is provided above the interlocking arm 22. This interlocking arm stop member
Reference numeral 28 is attached to the sheet feeding frame 4, and abuts on the interlocking arm 22 to define an upper movement limit when the interlocking arm 22 swings.

A seat surface sensor 21 is provided approximately in the middle of the interlocking arm 22 in the longitudinal direction. This sheet surface sensor 21 is a photo interrupter as in the first embodiment,
The light-shielding detects a relative position change between the acting portion 20b of the seat surface contact member 20 and the seat surface sensor 21 of the interlocking arm 22.

The seat surface abutting member 20 is rotatably attached to the sheet feeding frame 4 by a seat surface abutting member support 27, and a contact portion 20a is extended downward, and The action portion 20b extended toward the interlocking arm 22 is combined with the seat surface sensor 21.

Next, the operation and action of the above-described constituent elements when the sheet 5 is conveyed will be described depending on the amount of curl generated on the sheet 5. As in the first embodiment, the standard position H1 is the height at which the sheet surface sensor 21 detects the position of the acting portion 20b of the sheet surface contact member 20 and the lifting of the sheet lifting tray 30 is stopped.

When the curl amount of the sheet 5 is negligible, when the uppermost surface of the sheet 5 is raised by the sheet elevating tray 30 and approaches the feeding area, the contact portion at the tip of the sheet surface abutting member.
20a contacts the seat 5 and rises together with the seat 5, and the seat surface contact member 20 rotates about the seat surface contact member support 27. Along with that, the action part 20 to the seat surface sensor 21
The b also rotates, and the height of the sheet 5 is recognized by the sheet surface sensor 21 detecting the change in the relative position between the acting portion 20b and the sheet surface sensor 21, and the sheet lifting tray 30 is stopped in the feeding area. It Here, when a sheet conveying command is sent from the image forming apparatus 2 to the sheet conveying apparatus 1, the pickup roller 10 descends onto the sheet 5 and sends the sheet 5 to the separation roller pair.

When the curl occurs within the allowable range of the sheet conveying device, the sheet edge height detecting member 23a rises according to the curl amount. The seat edge height detection member 23a is rotatably attached to the interlocking arm 22 upward, but since it is biased downward by the elastic member 24, the seat edge height detection member 23a rises as the seat edge height detection member 23a rises. The interlocking arm 22 also rises. Therefore, the standard position detected by the seat surface sensor 21
H1 also rises. That is, as the curl increases, the standard position H1 also increases, and accordingly, the sheet lifting tray 30
Can be stopped at a higher position, and the center of the sheet, which has been relatively lowered than the sheet edge due to the curl, can be raised. Therefore, it is possible to stop the sheet raising / lowering tray 30 at an appropriate position and pick up the sheet 5 having a substantially constant height regardless of the fact that the curl is not pressed.

When the curl exceeding the allowable amount of the sheet conveying device is generated, the interlocking arm stop member 28 moves to the interlocking arm before the sheet surface sensor 21 detects that the sheet 5 reaches the standard position H1. The contact is made and the rotation of the interlocking arm 22 is stopped. Therefore, the rise of the height of the standard position H1 is also stopped, and this is the upper limit. When the sheet raising / lowering tray 30 continues to move upward, the sheet end height detecting member 23a rotates upward about the shaft 22b while the interlocking arm 22 is stopped. That is, the sheet elevating tray 30 can continue to rise without being pressed by the curl of the sheet 5.

When the sheet raising / lowering tray 30 further continues to rise, the sheet surface abutting member 20 abuts on the sheet 5 and ascends, so that the acting portion 20b of the sheet surface abutting member 20 moves to the sheet surface sensor.
The sheet surface sensor 21 detects that the sheet 5 has reached the standard position H1 by moving up to the position 21 and the sheet lifting tray 30
Stop rising. The height at which the sheet lifting tray 30 is stopped is the height of the sheet 5 in which the curl exceeds the allowable amount.
The central portion of the sheet is set to a height that does not reach the pickup roller 10, and the sheet 5 in which the curl exceeding the allowable amount has occurred is not delivered to the downstream conveying device or image forming apparatus. From these things, the interlocking arm stop member 28
The allowable curl amount of the sheet 5 to be sent can be set by adjusting the height of the sheet.

[Third Embodiment] A third embodiment of a sheet conveying device and an image forming apparatus having the same according to the present invention will be described with reference to FIGS. It should be noted that parts that are the same as those of the first or second embodiment will be designated by the same reference numerals and the description thereof will be omitted. FIG. 6 is a layout view around the pickup roller, and FIG. 7 is a perspective view of a sheet surface sensor and a sheet surface contact member.

In this embodiment, the end of the interlocking arm 22 on the pickup roller 10 side is rotatably attached to the sheet feeding frame 4 by the interlocking arm support 25 so that it can swing in the vertical plane. It is possible. The other end of the interlocking arm 22 has a seat edge height detection member.
23a is integrally provided. Further, the sheet end height limiting member 26 is provided on the seat side guide 35a above the sheet end height detecting member 23c to define the upper limit of the movement of the sheet end height detecting member 23a.

Next, the operation and action of the above-mentioned constituent elements when the sheet 5 is conveyed will be described depending on the amount of curl generated in the sheet 5. As in Embodiments 1 and 2, the seat surface sensor 21 detects the position of the action portion 20b of the seat surface abutting member 20, and the height at which the lifting of the seat lifting tray 30 is stopped is set to the standard position H1.

If the curl amount of the sheet 5 can be ignored, the sheet surface contact member 20 detects the height of the uppermost surface of the sheet 5 by the sheet surface contact member 20, and the sheet elevating tray 30 is moved. Stop raising and pick up roller 10
Thus, the sheet 5 is sent to a separation roller pair (not shown).

When the curl occurs within the allowable range of the sheet conveying device, the sheet edge height detecting member 23c rises according to the curl amount, and the interlocking arm 22 also rises accordingly. Then, the standard position H1 detected by the sheet surface sensor 21 also rises, and accordingly, the sheet raising / lowering tray 30 is also stopped at a higher position, so that the center of the sheet, which is relatively lowered from the sheet edge due to curl, is raised. You can Therefore, it is possible to stop the sheet raising / lowering tray 30 at an appropriate position and pick up the sheet 5 having a substantially constant height regardless of the fact that the curl is not pressed.

When the curl exceeds the allowable amount of the sheet conveying device, the sheet edge height detecting member 23c is detected before the sheet surface sensor 21 detects that the sheet 5 has reached the standard position H1. In contact with the seat edge height limiting member 26,
At the same time when the ascending of the interlocking arm 29 is stopped, a signal is sent to the sheet elevating tray 30 to stop the ascending. At this time, the central portion of the sheet 5 has not reached the pickup roller 10 yet, and the sheet 5 is not delivered toward the downstream conveying device or the image forming apparatus. That is, by adjusting the height of the sheet edge height limiting member 26, the sheet 5 to be fed
The allowable curl amount of can be set.

Although the feeding member has been described as the pickup roller in the present embodiment, the present invention is not limited to this and may be a rotating belt or the like.

[0042]

The sheet conveying apparatus of the present invention does not have a sheet edge restraining mechanism for correcting the curl of a conveyed sheet, and the feeding member and the sheet surface height detecting means are perpendicular to the conveying direction in the sheet surface. It was placed away in the direction of. As a result, when the curl amount increases, a difference occurs in the height of the sheet at the position of the sheet surface height detecting means and the position of the sheet feeding member, so that the sheet surface height detecting member starts feeding the sheet height. Even if it is determined that the sheet is at the position, the feeding member does not contact the sheet, and therefore the sheet is not fed. That is,
By properly arranging the distance between the feeding member and the sheet surface height detection member, it is possible to set the allowable range for the curl amount of the sheet, and the curl amount that causes malfunction such as paper jam or conveyance failure. It is possible to prevent a large number of sheets from being sent to the downstream sheet conveying apparatus and the image forming apparatus, and maintainability is improved.

Further, since the pickup portion is constructed without providing the sheet edge restraining mechanism, it is possible to prevent pickup failure due to friction between the sheet and the sheet edge restraining mechanism.

Further, when the sheet edge height detecting means is provided and the sheet surface height detecting member is configured to interlock with the sheet edge height detecting means, feeding start detected by the sheet surface height detecting means The position swings following the height of the sheet edge.
As a result, the center of the sheet, which was relatively low due to curl, can be picked up at a higher position, and it is possible to pick up and feed at a substantially constant position without pressing the curl. It will be possible.

Further, by setting the upper limit in the moving range of the sheet edge height detecting means, it is possible to set the upper limit in the moving range of the sheet surface height detecting means. Therefore, when the curl is larger than a certain amount, even if the sheet surface height detecting means detects the feeding start position and stops the lifting mechanism, the feeding member is not in contact with the sheet and the sheet is fed. Never.
That is, by setting the upper limit of the sheet edge height detecting means, it is possible to set a limit on the curl amount of the sheet to be sent out, and a sheet with a large curl amount that causes a malfunction such as a paper jam or a conveyance failure can be set downstream. It is possible to prevent the sheet from being fed into the sheet conveying apparatus and the image forming apparatus, and the maintainability is improved.

By mounting the above-described sheet conveying device in the image forming apparatus, it is possible to provide an image forming apparatus which does not cause a malfunction such as a paper jam.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an image forming apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a configuration of a sheet lifting mechanism of the sheet conveying device according to the first embodiment.

FIG. 3 is a layout diagram around a pickup roller according to the first embodiment.

FIG. 4 is a layout diagram around a pickup roller according to the second embodiment.

FIG. 5 is a perspective view of a seat surface sensor and a seat surface contact member according to the second embodiment.

FIG. 6 is a layout diagram around a pickup roller according to a third embodiment.

FIG. 7 is a perspective view of a seat surface sensor and a seat surface contact member according to a third embodiment.

FIG. 8 is a layout diagram around a pickup roller showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sheet transport device, 2 ... Image forming device, 3 ... Controller and power supply unit, 4 ... Sheet supply frame, 5 ... Sheet, 6 ... Sheet transport path, 7 ... Optical system, 10 ... Pickup roller, 11 ... Feed roller, 12 ... retard roller, 13
a, 13b, 13c ... Conveying roller, 14 ... Registration roller, 15 ... Photosensitive drum, 16 ... Transfer roller, 17 ... Thermal fixing device, 18 ... Discharge roller, 19 ... Discharge tray, 20 ... Sheet surface contact member, 20
a ... Contact part, 20b ... Working part, 21 ... Seat surface sensor, 22, 2
9 ... Interlocking arm, 23a, 23b, 23c ... Seat edge height detecting member, 25 ... Interlocking arm support tool, 26 ... Seat edge height limiting member, 27 ... Seat surface abutting member support tool, 28 ... Interlocking arm stop member , 30 ... Sheet lifting tray, 31 ... Storage, 32 ... Motor, 33 ... Lifting wire, 34 ... Driving force transmission mechanism, 35a, 35b ...
Seat side guide, 36 ... Take-up shaft, 37 ... Take-up reel, 38a, 38b ... Pulley

Claims (4)

[Claims] 1. A sheet conveying device main body, a stacking member on which sheets to be conveyed are stacked, an elevating mechanism for raising and lowering the stacking member, and a sheet surface for detecting a sheet surface height of the sheets stacked on the stacking member. A sheet conveying apparatus having height detection means and a feeding member for feeding the sheet, wherein the sheet surface height detection means is provided to the feeding member within a plane of the sheet stacked on the stacking member. A sheet conveying device, which is arranged separately in a direction perpendicular to the conveying direction. 2. The sheet conveying device is provided with a sheet edge height detecting means that can move up and down while contacting a sheet edge portion, and the sheet surface height detecting means is interlocked with the sheet edge height detecting means. The sheet conveying device according to claim 1, wherein the sheet conveying device is vertically movable. 3. The sheet edge height detecting means according to claim 2, further comprising means for detecting that a certain height is reached when the sheet edge height detecting means comes into contact with the sheet and moves upward. Sheet transport device. 4. A sheet conveying device according to any one of claims 1 to 3, further comprising a conveying unit that conveys a sheet conveyed by the sheet conveying device further downstream, and a conveying unit that conveys the sheet. And an image forming unit for forming an image on the formed sheet according to image information.