JP2006298589A - Sheet feeding device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeding device in which a sheet storage means can be securely and automatically fitted into a normal fitting position without damaging operability, and an image forming device. <P>SOLUTION: When the sheet storage means is set to a device body, a lift means 30A provided in the sheet storage means and pushing up a sheet loading plate 33 to make sheets loaded on the sheet loading plate 33 pressure contact with the sheet feeding means is engaged with a pressing drive means 30 provided in the device body, engaged with the lift means 30A to be driven. Due to drive force of the pressing drive means 30 transmitted to the lift means 30A, the sheet loading plate 33 is pushed up, and transfer force for transferring the sheet storage means from a predetermined position before the fitting position to the fitting position is generated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly to an apparatus having a pull-in function for pulling in a sheet storage unit.

  2. Description of the Related Art Conventionally, in an image forming apparatus having a sheet feeding device having a sheet storing means for storing sheets, such as a sheet storing cassette, sheets stacked inside a sheet storing cassette disposed at a supply position of the apparatus main body are stored. The images are sequentially supplied to the image forming unit, and the image forming unit forms an image on the sheet.

  By the way, the sheet storage cassette is attached to and detached from the apparatus main body manually by the user for filling the sheet or changing the sheet size. However, when the sheet storage cassette is manually inserted into the apparatus main body, the sheet is filled. In some cases, the sheet storage cassette is not pushed to the proper mounting position of the apparatus main body. In such a case, the sheet storage cassette is not positioned. As a result, an image is not accurately formed on the sheet or a conveyance failure may occur.

  Further, when the weight of the sheet storage cassette is increased, there is a problem that a heavy burden is imposed on the user during the insertion operation. Furthermore, when the sheet storage cassette is heavy, momentum is often applied during the insertion operation into the apparatus main body. In this case, the sheet storage cassette collides with the apparatus main body due to this momentum when reaching the proper mounting position. There are also problems such as misalignment of stacked sheets.

  Here, as an example of conventional means for solving these problems, when insertion of the sheet storage cassette is detected by the detection means, the cassette transfer means for transferring the sheet storage cassette is driven by a driving means such as a motor, and the sheet There has been proposed a configuration in which the user does not insert the sheet storage cassette by automatically transferring the storage cassette to a regular mounting position (see, for example, Patent Document 1).

  However, with the above configuration, when the power of the apparatus main body is not turned on, or when the image forming apparatus is not used for a long time and the standby state is set in the energy saving mode and power is not supplied to the driving unit, In order to drive the drive means or to drive the drive means, a charge mechanism for storing energy is required, and there is a problem that the apparatus itself is complicated and large.

  Therefore, as an example of conventional means for solving these problems, when the sheet storage cassette is inserted to a predetermined position of the apparatus main body, a normal mounting position is automatically set by a toggle mechanism (toggle spring) without using a driving means such as a motor. A mechanism has been proposed that can be retracted up to. As a result, operability is improved with a compact mechanism that does not require power supply (see, for example, Patent Document 2).

JP-A-2-198925 JP-A-4-85220

  However, in such a conventional sheet feeding apparatus and an image forming apparatus equipped with the same, a force for pulling the sheet storage cassette into the apparatus main body is generated by the toggle spring, so that it is necessary for the sheet storage cassette having a large capacity. There was a problem that the spring force became very large.

  Further, when a detection means for detecting the sheet size is provided at the final position of the drawing of the sheet storage cassette, there is a load for detecting the sheet size by the detection means, and the pulling operation is overcome by overcoming this. In order to do this, it was necessary to further increase the spring force of the toggle spring.

  However, when the spring force of the toggle spring is increased as described above, the sheet storage cassette can be automatically mounted in the proper mounting position. However, when the user pulls out the sheet storage cassette from the main body of the apparatus, a very strong toggle spring is used. Therefore, an operation force greater than the spring force is required, resulting in a problem that the operability is deteriorated.

  Accordingly, the present invention has been made in view of the above problems, and is a sheet feeding apparatus capable of automatically and reliably mounting a sheet storage cassette (sheet storage means) at a regular mounting position without impairing operability. An object of the present invention is to provide an image forming apparatus.

  In order to achieve the above object, the present invention provides a sheet feeding apparatus having a sheet stacking plate that can be moved up and down by stacking sheets, and includes sheet storage means that is detachably attached to the apparatus body. A sheet feeding unit that is provided above the storage unit and feeds the sheets stored in the sheet storage unit; and provided in the sheet storage unit, the sheet stacking plate is pushed up and stacked on the sheet stacking plate. A lift unit that presses the sheet against the sheet feeding unit; and a pressure drive unit that is provided in the apparatus main body and is driven by being engaged with the lift unit. When the sheet is set, the lift means is engaged with the pressure driving means, and the sheet stacking plate is pushed up by the driving force of the pressure driving means transmitted to the lift means. It is characterized in that to generate a transport force for transporting the sheet accommodating means from the predetermined position before the mounting position to the mounting position.

  As in the present invention, when the sheet storage means is set in the apparatus main body, the lift means provided in the sheet storage means is engaged with the pressure driving means provided in the apparatus main body, and the pressure transmitted to the lift means is transmitted. By generating a transfer force to transfer the sheet storage means from the predetermined position before the mounting position to the mounting position by the driving force of the driving means, the sheet storage means is automatically automatically set to the normal mounting position without impairing the operability. Can be installed.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 5 shows a schematic configuration of the image forming apparatus including the sheet feeding apparatus according to the first embodiment of the present invention.

  In FIG. 5, reference numeral 1 denotes an image forming apparatus main body. Reference numeral 1A denotes an image forming unit that is provided in an image forming apparatus main body (hereinafter referred to as an apparatus main body) 1 and forms an image by an electrophotographic method. Device.

  The image forming unit 1A includes a photosensitive drum 2 that forms a toner image, a transfer roller 3 that transfers the toner image formed on the photosensitive drum 2 to a sheet S, and the like. In the image forming unit 1A having such a configuration, when an image forming operation is started, light corresponding to the image signal is first irradiated to the photosensitive drum 2 by the laser scanner 4, and the image signal corresponding to the image signal is received. By irradiating light, a latent image is formed on the photosensitive drum. Next, the latent image is developed with toner stored in the process cartridge 5 to form a toner image (visible image) on the photosensitive drum.

  The sheet feeding apparatus 1 </ b> C is provided with a plurality of sheet storage cassettes 6 serving as sheet storage units, and a sheet feeding unit that is provided above the sheet storage cassette 6 and that feeds sheets S stored in the sheet storage cassette 6. The sheet S is fed from the sheet storage cassette 6 by the feed roller 7a in parallel with the toner image forming operation.

  The sheet S thus fed from the sheet storage cassette 6 is synchronized with the image formed on the photosensitive drum 2 by the conveying roller 7 and the registration roller 7A, and is synchronized with the photosensitive drum 2 and the transfer roller 3. It is transported to the transfer section that is configured. In this transfer portion, a toner image is transferred to the sheet S by applying a bias to the transfer roller 3.

  The sheet S on which such a toner image has been transferred is then conveyed to the fixing unit 8 and is heated by the fixing unit 8 to fix the toner image. It is discharged to the upper discharge unit 10.

  Here, the sheet storage cassette 6 is stored in a sheet storage cassette storage section 1B provided in the apparatus main body 1, specifically, in the sheet feeding apparatus main body as shown in FIG. 1 and FIG. It can be attached and detached along the slide guide 15.

  Further, as shown in FIG. 6 to be described later, the sheet storage cassette 6 can be slidably adjusted to correspond to an arbitrary sheet size, and a side regulating plate 11 for regulating the position in the width direction of the sheet and the sheet A rear end regulating plate 12 for regulating the rear end is provided. Note that the sheet storage cassettes 6 in each stage have the same configuration.

  By the way, as shown in FIG. 1, an inner plate 33 as a sheet stacking plate on which sheets S are stacked is provided in the sheet storage cassette 6 so as to be rotatable (movable up and down) in the vertical direction. The intermediate plate 33 is moved to the feeding roller side by a lifter mechanism 30B provided with a pressure feeding unit 30 as a pressure driving unit provided on the apparatus main body side and a lift unit 30A provided on the sheet storage cassette side. It can be pushed up.

  The lift means 30A includes a lift arm 32 that is rotatably provided between the bottom surface of the sheet storage cassette 6 and the intermediate plate 33, and a lift gear 31 that is erected on one end of the lift arm 32. The cassette gear 34 is provided in the sheet storage cassette 6.

  2 shows a state when the sheet storage cassette 6 is attached to the apparatus main body 1. When the sheet storage cassette 6 is thus attached, the lift means 30A is added as shown in FIG. Connected (engaged) to the pressure paper feed drive unit 30.

  Then, by connecting the lift means 30A and the pressure feed driving unit 30 in this way, when the pressure feed driving unit 30 is driven thereafter, the driving force of the pressure feed driving unit 30 is driven. Is transmitted to the lift arm 32 by the cassette gear 34, and the lift arm 32 rotates upward while contacting the intermediate plate 33 from below. Accordingly, the intermediate plate 33 is rotated toward the feeding roller, so that the sheets S stacked on the intermediate plate 33 come into pressure contact with the feeding roller 7a (see FIG. 1).

  FIG. 3 is a diagram showing the configuration of such a pressure paper feed drive unit 30. The pressure paper feed drive unit 30 meshes with a cassette gear 34 (see FIG. 1) and transmits a driving force. 35, a pressure motor 40 for rotating the drive transmission gear 35, a worm gear 39 provided on the pressure motor 40, a ratchet gear 38 connected to the worm gear 39, and the like.

  In FIG. 3, reference numerals 36 and 37 denote a first reduction gear and a second reduction gear disposed between the drive transmission gear 35 and the pressure motor 40. The drive transmission gear 35 includes a worm gear 39 and a ratchet gear 38. The drive of the pressurizing motor 40 is transmitted via the second reduction gear 37 and the first reduction gear 36 that are integrally provided with a ratchet portion. When an excessive load is applied to the drive transmission gear 35 and the like, the drive is cut off between the ratchet gear 38 and the second reduction gear 37, thereby preventing the pressure feed unit 30 from being damaged. is doing.

  Here, as in the present embodiment, since a large reduction ratio can be obtained by providing the worm gear 39 in the speed reduction means, the pressure paper feed drive unit 30 can be made compact.

  Further, in the present embodiment, the cassette gear 34 and the drive transmission gear 35 are constituted by helical gears as shown in FIG. 1 and FIG. 3, respectively, so that when the drive transmission gear 35 rotates, A force in the A direction is generated from the rotational direction and the twist angle direction of the helical gear.

  By the way, the apparatus main body 1 is provided with a detection means (not shown) for detecting the sheet storage cassette 6 before the mounting is completed when the sheet storage cassette 6 is inserted into the apparatus main body 1. When the sheet storage cassette 6 is detected, a pressurizing motor 40 in the pressurizing and feeding unit 30 is driven by a control unit (not shown).

  Further, when the pressurizing motor 40 is driven in this way, the drive transmission gear 35 constituted by a Hasuba gear via the worm gear 39, the ratchet gear 38, the second reduction gear 37, and the first reduction gear 36 is accompanied by this. Driven.

  When the drive transmission gear 35 is driven in this way, it engages with the drive transmission gear 35 and, similarly to the drive transmission gear 35, the cassette gear 34 formed of a helical gear has a direction indicated by an arrow A in FIG. That is, a force is generated in the direction in which the sheet storage cassette 6 is mounted on the apparatus main body 1, and the sheet storage cassette 6 can be reliably transferred to a proper mounting position by this force.

  As described above, when the sheet storage cassette 6 is set in the apparatus main body 1, the lift means 30 </ b> A provided in the sheet storage cassette 6 is engaged with the pressurization paper feeding drive unit 30 provided in the apparatus main body 1, thereby lifting the lift means. The apparatus main body 1 of the sheet storage cassette 6 is generated by generating a transfer force for transferring the sheet storage cassette 6 from a predetermined position before the mounting position to the mounting position by the driving force of the pressure feeding unit 30 transmitted to 30A. The insertion operation can be automated.

  As a result, even with a large capacity sheet storage cassette 6, the operability of the sheet storage cassette 6 is improved, and the sheet storage cassette 6 can always be mounted at a regular mounting position, so that image misalignment with respect to sheets or sheet conveyance such as jamming is performed. It is possible to prevent the occurrence of problems such as defects.

  In the present embodiment, the case where the cassette gear 34 of the lifting means 30A and the drive transmission gear 35 of the pressure feeding drive unit 30 are helical gears as means for generating the transfer force for transferring the sheet storage cassette 6 will be described. However, other than this, for example, a coupling means may be used, and a coupling force may be generated in the insertion direction in the sheet storage cassette 6 by forming the coupling engaging portion obliquely.

  Next, a second embodiment of the present invention will be described in detail.

  In the following, portions different from the first embodiment will be described in detail, and descriptions of other portions having the same configuration will be omitted.

  FIG. 6 is a perspective view of the sheet storage cassette provided in the sheet feeding apparatus according to the present embodiment. The sheet storage cassette 6 is provided in the apparatus main body 1 when mounted, as shown in FIG. A rack 13 is provided which meshes with the cassette transfer means 16 shown. The sheet storage cassette 6 is detachable from the apparatus main body 1 along the slide guide 15 as shown in FIG.

  Here, the cassette transfer means 16 is for pulling in the sheet storage cassette 6 when the sheet storage cassette 6 is set in the apparatus main body 1, and the sheet storage cassette 6 is moved to a predetermined position before the regular mounting position. When inserted, the sheet storage cassette 6 is engaged. When the sheet storage cassette 6 is further inserted from the engaged state, a transfer force is generated in the insertion direction.

  As shown in FIG. 8, the cassette transfer means 16 meshes with a rack 13 attached to the sheet storage cassette 6 and transmits an intermediate gear 14 for transmitting power, a toggle spring 17 as a power source for transfer drive, A toothless gear 18 as a driving member that meshes with the gear 14 and transmits the power generated by the toggle spring 17 and an arm 19 that supports the toothless gear 18 are provided.

  Further, a piston type as a brake when the sheet storage cassette 6 is pulled in by the cassette transfer means 16 and when the user inserts the sheet storage cassette 6 with momentum in the insertion operation of the sheet storage cassette 6. An air damper 20 is provided.

  By the way, in the cassette transfer means 16 using such a toggle spring 17, as shown in FIG. A toggle spring 17 is engaged between the spring hanging shaft A23 and a spring hanging shaft B24 as a support shaft standing on the base 21, and the arm 19 obtains a rotational force by the contraction force of the toggle spring 17.

  By providing such a cassette transfer means 16, the sheet storage cassette 6 is inserted by the user, and the rack 13 attached to the rear plate of the sheet storage cassette 6 is connected to the back of the sheet storage cassette storage portion 1 B. When reaching the position of the cassette transfer means 16 attached to the side plate, the remaining section is transferred by the cassette transfer means 16 to the mounting position where the sheet can be fed.

  FIG. 9 shows a state immediately before the sheet storage cassette 6 is mounted in the sheet storage cassette storage portion 1B and reaches the cassette transfer means 16. At this time, the toggle spring 17 is a fulcrum shaft shown in FIG. 22, the spring-loaded shaft A 23 and the spring-loaded shaft B 24 are at a position shifted in the opposite direction from the neutral point when the tray conveying force is generated, from the neutral point aligned in a straight line.

  FIG. 10 shows a state in which the toggle spring 17 has the fulcrum shaft 22, the spring hanging shaft A23, and the spring hanging shaft B24 aligned in a straight line. Will be neutral.

  Then, when the external force from the toggle spring 17 is applied to the arm 19 in the clockwise direction or the counterclockwise direction with respect to the neutral state as a boundary, and the positional relationship in the neutral state is broken, the neutral state is deviated as shown in FIG. The arm 19 is rotated by the contraction force of the toggle spring 17, and the rotational force is transmitted to the intermediate gear 14 from the toothless gear 18 supported by the arm 19, and becomes a transfer force of the sheet storage cassette 6.

  Next, the sheet storage cassette pull-in operation of the cassette transfer means 16 using such a toggle spring 17 will be described.

  First, when the sheet storage cassette 6 is pulled out to the sheet replenishment position, the cassette transfer means 16 stands by in a state as shown in FIG. At this time, the toggle spring 17 is stopped by a stopper (not shown) at a standby position slightly deviated in the opposite direction (one direction) to the neutral state when the tray transfer force is generated. The arm 19 is prevented from rotating beyond the neutral state due to a factor.

  In this state, the sheet storage cassette 6 is inserted into the sheet storage cassette storage portion by the user's operation, reaches the position where the tip of the rack 13 meshes with the intermediate gear 14 as shown in FIG. 9, and the sheet storage cassette 6 is inserted. Then, the intermediate gear 14 starts to rotate, the rotation is transmitted to the toothless gear 18, and the arm 19 rotates to the neutral position shown in FIG.

  When the sheet storage cassette 6 is further inserted and the arm 19 is rotated in the other direction beyond the neutral state, the load acting direction of the toggle spring 17 is reversed, and the arm 19 is toggled as shown in FIG. A rotational force is obtained by the contraction force of 17, and the drive is transmitted to the rack 13 via the toothless gear 18 and the intermediate gear 14, and the sheet storage cassette 6 is transferred toward the mounting position.

  When the transfer of the sheet storage cassette 6 is started in this way, the piston type damper 20 is operated to adjust the transfer speed of the sheet storage cassette 6. The piston-type damper 20 acts as a brake when the sheet storage cassette 6 is vigorously inserted.

  As described above, when the sheet storage cassette 6 is stored from the drawing position for supplying sheets and the toggle spring 17 of the cassette transfer means 16 is moved to a position away from the neutral state, the contraction force of the toggle spring 17 causes the contraction force of the toggle spring 17 to move. The sheet storage cassette 6 is automatically pulled into the mounting position. Further, the speed is adjusted by the piston type air damper 20.

  In the state where the sheet storage cassette 6 is attached to the apparatus main body 1, the sheet storage cassette 6 is not pulled out from the apparatus main body 1 because the pressure is always applied in the insertion direction by the pressure of the toggle spring 17.

  By the way, as described above, there is a load such as detection of the sheet size by the detection means (not shown) at the final position of drawing of the sheet storage cassette 6, and in order to overcome this and perform the pulling operation, the sheet storage cassette 6 has a load. It is necessary to increase the pulling force.

  Therefore, in the present embodiment, a lifter mechanism including a pressurization sheet feeding drive unit 30 provided on the apparatus main body side having the same configuration as that of the first embodiment, and lift means 30A provided on the sheet storage cassette side. 30B is provided.

  When the detection means detects the sheet storage cassette 6, the control unit (not shown) drives the pressurization motor 40 in the pressurization and paper feed drive unit 30, and the worm gear 39, the ratchet gear 38, and the second reduction gear 37. The drive transmission gear 35 is driven via the first reduction gear 36.

  Here, when the drive transmission gear 35 is driven in this manner, the cassette gear 34 and the drive transmission gear 35, which are configured by a helical gear, as shown in FIGS. 1 and 3, the rotational direction and the helical angle direction of the helical gear, A force is generated in the direction A shown in FIGS. 1 and 4, that is, the direction in which the sheet storage cassette 6 is attached to the apparatus main body 1.

  With this configuration, even when the sheet storage cassette 6 is not sufficiently pulled in by the cassette transfer means 16, if the drive for rotating the lift arm 32 to lift the intermediate plate 33 is transmitted, the sheet storage cassette 6 is driven by that drive. Will move to the proper mounting position of the apparatus body 1.

  As a result, the sheet storage cassette 6 can be securely stored in the apparatus main body 1 without increasing the spring force of the toggle spring 17, so that the burden on the user when inserting the sheet storage cassette 6 can be reduced. Furthermore, it is possible to reduce the operating force when pulling out the sheet storage cassette 6, and the burden on the user can be reduced.

  Further, since the sheet storage cassette 6 can be surely moved to the mounting position automatically in the vicinity of the mounting position, it is possible to prevent the problem of defective mounting of the sheet storage cassette 6, and as a result, the sheet storage cassette 6 is properly It is possible to prevent a sheet feeding failure such as a jam that occurs when the sheet feeding operation is performed in a state where it is not in the mounting position.

  In addition, this invention is not limited to the said embodiment, For example, you may make it mesh | engage the rack 13 and the missing gear 18 directly, without using the intermediate | middle gear 14. FIG. In this case, the rotation direction of the arm 19 by the toggle spring 17 is configured to be opposite to that of the above embodiment.

1 is a perspective view showing a state when lift means provided in a sheet storage cassette of a sheet feeding apparatus according to a first embodiment of the present invention and a pressure feed driving unit provided in an apparatus main body are connected. FIG. . The perspective view which shows a state when the said sheet | seat storage cassette is mounted | worn with the apparatus main body. FIG. 3 is a detailed view of the inside of the pressurization paper feed drive unit. The figure which shows the meshing | engagement state of the gear provided in the said lift means and a pressurization paper feed drive unit. FIG. 3 is a diagram illustrating a schematic configuration of an image forming apparatus including the sheet feeding device. The perspective view of the sheet storage cassette provided in the sheet feeding apparatus which concerns on the 2nd Embodiment of this invention. FIG. 3 is a perspective view illustrating a state in which the sheet storage cassette is pulled out from the apparatus main body. FIG. 4 is a perspective view of a cassette transfer unit provided in the sheet feeding device. The top view which shows the sheet | seat storage cassette transfer start waiting state of the said cassette transfer means. The top view which shows the state in which the toggle spring was located in the neutral state in the said cassette transfer means. FIG. 6 is a top view showing a state in which the cassette transfer unit has transferred the sheet storage cassette to a feeding position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 1A Image forming part 1B Sheet storage cassette storage part 1C Sheet feeding apparatus 6 Sheet storage cassette 7a Feeding roller 13 Rack 16 Cassette transfer means 17 Toggle spring 18 Missing gear 20 Piston type air damper 22 Support shaft 23 Spring Hanging A
24 Spring hanging shaft B
30 Pressure feeding unit 30A Lifting means 30B Lifter mechanism 32 Lift arm 33 Middle plate 34 Cassette gear 35 Drive transmission gear 40 Pressure motor S Sheet

Claims (6)

In a sheet feeding apparatus having a sheet stacking plate that can be moved up and down by stacking sheets, and provided with sheet storage means that is detachably attached to the apparatus main body,
A sheet feeding means which is provided above the sheet storage means and feeds the sheets stored in the sheet storage means;
A lift means provided in the sheet storage means for pushing up the sheet stacking plate to press the sheets stacked on the sheet stacking plate against the sheet feeding unit;
A pressure driving means provided on the apparatus main body and engaged with and driven by the lift means;
With
When the sheet storage means is set in the apparatus main body, the lift means is engaged with the pressure driving means, and the sheet stacking plate is pushed up by the driving force of the pressure driving means transmitted to the lift means. And a sheet feeding device that generates a transfer force for transferring the sheet storage means from a predetermined position before the mounting position to the mounting position. Pull-in driving means provided in the apparatus main body and engaged with the sheet storage means set in the apparatus main body in front of the mounting position to draw the sheet storage means to the mounting position;
With
When the sheet storage means is set in the apparatus main body, the sheet storage means is caused by the transfer force generated by the driving force of the pressure driving means transmitted to the lift means and the pulling force of the pulling drive means. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is transported to the mounting position.   The pressurizing drive means and the lift means each have a gear for transmitting the drive of the pressurization drive means to the lift means, and the gears are helical gears, and the sheet storage is performed by a force generated by a twist angle of the helical gears. 3. A sheet feeding apparatus according to claim 1, wherein the sheet feeding device is transported. The pull-in drive means includes a rotatable drive member, and a toggle spring having one end supported by the apparatus main body by a support shaft and the other end supported by the drive member by a support shaft,
From the state in which the support shaft line is located on one side of the rotation fulcrum, with the support shaft line connecting the support shafts respectively supporting both ends of the toggle spring as a boundary in a neutral state where the support shaft line coincides with the rotation fulcrum of the drive member. 3. The sheet feeding apparatus according to claim 2, wherein the sheet storage means is transferred by a pulling force using an elastic force of the toggle spring after the support shaft moves beyond the neutral state to the other side.   3. The sheet feeding apparatus according to claim 2, further comprising a damper that decelerates a moving speed of the sheet storage unit when the sheet storage unit is transferred. The sheet feeding device according to any one of claims 1 to 5,
An image forming unit that forms an image on a sheet fed from the sheet feeding device;
An image forming apparatus comprising:

Images