JP2002202644A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the supporting stability of the case of an image reading part in an image forming device, which has a sheet stacking part for ejecting a recorded recording sheet between the image reading part and an image formation part and in which the area of the sheet stacking part on this side and one area on an end part side in a width direction are opened. SOLUTION: The case 6 of the image reading part is fixed on a stud 32 fixed at a device body base 25, a driving unit 27 and the support 30 of the device body base, and a supporting part 36 to support the case 6 from a lower side is added to a stay 31 fixed at the support 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an image reading section for reading a document image and an image forming section for forming a recorded image on a recording sheet, and the image forming section is arranged below the image reading section. A sheet stacking unit for stacking a recording sheet on which a recording image is formed by the image forming unit is disposed between the image reading unit and the image forming unit; and a sheet stacking unit on the front side of the image forming apparatus main body. The present invention relates to an image forming apparatus in which a case of the image reading unit is fixedly supported on a main body base in a state where an area and a sheet stacking area on one end side in the width direction of the image forming apparatus main body are open.

For example, an image forming apparatus of the above-described type configured as a copier, a printer, a facsimile, or a multifunction machine thereof has been conventionally known. According to this type of image forming apparatus, the recording sheet on which the recording image is formed in the image forming section is discharged to the sheet stacking section between the image reading section and the image forming section. As compared with an image forming apparatus that discharges a recording sheet onto a sheet discharge tray that protrudes greatly, the size of the structure can be reduced and the installation space can be reduced. Moreover, since the sheet stacking portion area on the front side of the image forming apparatus main body and the sheet stacking section area on one end side in the width direction of the image forming apparatus main body are open,
The recording sheet discharged to the sheet stacking section can be easily taken out.

In this type of image forming apparatus, since the above-mentioned two sheet stacking sections are open, the case of the image reading section is provided at one corner, that is, at the front side of the image forming apparatus main body and at the image forming side. The corner portion on one end side in the width direction of the forming apparatus main body is not supported from below by the main body base. For this reason, the case of the image reading unit is
Due to its own weight, there is a possibility that the corner portion is deformed into a state of being largely twisted in a direction of being displaced downward.

If an image of a document is read by the image reading section in such a state, and an image corresponding to the image information is formed on a recording sheet, the image is distorted and the image quality is significantly reduced.

Therefore, it is conceivable to increase the rigidity of the case of the image reading unit so that the case is not substantially deformed by the weight of the image reading unit. However, configuring the case in this way increases the cost and the weight.

In view of this, a stay is fixed to a main body base portion at one end side in the width direction of the image forming apparatus main body, and the stay is formed in a cantilever shape protruding toward the front side of the image forming apparatus main body. However, if the case of the image reading unit is fixed to such a stay, it is possible to prevent the case from being greatly twisted and deformed without excessively increasing the rigidity of the case.

However, when the case of the image reading section is fixed to the stay during the manufacture of the image forming apparatus, the case is deformed by its own weight, so that the case may not be fixed at the correct height position with respect to the stay. There is.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus of the type described at the outset, in which all of the above-mentioned conventional disadvantages have been eliminated.

[0009]

In order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning, wherein one side of the case of the image reading section in the width direction of the main body of the image forming apparatus. Portion is fixedly supported by a stay fixed to the main body base, and the stay is formed in a cantilever shape protruding toward the front side of the image forming apparatus main body from a fixing portion fixed to the main body base, An image forming apparatus is proposed in which the stay is provided with a support for supporting the case from below before fixing the case to the stay (claim 1).

At this time, the support portion is provided at a position closer to the free end side of the stay than the fixing portion of the stay,
The height of the supporting portion before placing the case on the supporting portion,
It is advantageous that the size of the stay is set in consideration of the deformation amount of the stay so that the height of the support portion after the image reading unit is assembled becomes an appropriate height (claim 2).

Further, in the image forming apparatus according to claim 1 or 2, the stay is fixed to the main body base with a screw, and the screw is screwed into a bottom of a groove formed in the main body base. (Claim 3).

Further, in the image forming apparatus according to the third aspect, when the screw is tightened, the stay portion facing the bottom surface of the groove is elastically deformed, and the stay portion contacts the bottom surface of the groove. It is advantageous that the depth of the groove is set at the same time (claim 4).

[0013] Further, in the image forming apparatus according to the third aspect of the present invention, the stay portion facing the bottom surface of the groove is formed with a projection housed in the groove and projecting toward the bottom surface of the groove. It is advantageous that the depth of the groove is set so that the protrusion contacts the bottom surface of the groove when the screw is tightened (claim 5).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic vertical sectional view showing an arrangement state of each part of the image forming apparatus of the present embodiment, and FIG. 2 is an external perspective view of the image forming apparatus viewed obliquely from the front. The image forming apparatus shown here is configured as a multifunction machine having a copier, a printer, and a facsimile function, and an image reading unit 1 for reading a document image, and an image forming unit disposed below the image reading unit 1. The image forming unit 2 includes a sheet feeding unit 3 that feeds a recording sheet S to the image forming unit 2. The image forming section 2 serves to form a recording image on a recording sheet S made of paper or a resin sheet as described later. The image forming unit 2 is arranged below the image reading unit 1 with a space therebetween, and the image reading unit 1
Between the image forming unit 2 and the image forming unit 2, a sheet stacking unit 4 for stacking the recording sheets S on which the recording images are formed by the image forming unit 2 is arranged. The image reading unit 1, the image forming unit 2, and the sheet feeding unit 3
It is covered by the device housing 5.

The image reading section 1 of this embodiment includes a case 6 having an open top, various elements disposed in the case 6 and supported by the case 6, that is, a light source 7, and first to third mirrors 8 , 9, and 10, an imaging lens 11, and a CCD 12, which is an example of an optical conversion element. Above the case 6, a contact glass 13 fixed to the device housing 5 is provided.
Are placed, and the original P is placed on the contact glass 13. When the print start key of the operation unit 24 (FIG. 2) is pressed, the light source 7 and the first mirror 8, the second and third
The mirrors 9 and 10 move to the right in FIG. 1, and the light from the light source 7 illuminates the original P. As a result, the reflected light from the document P is reflected by the first to third mirrors 8, 9, and 10, and reaches the CCD 12 through the imaging lens 11. In this way, the original image is formed on the CCD 12, and the image is photoelectrically converted. As described above, the image reading unit 1 includes the optical system that forms an original image, the CCD 12 that is an example of a photoelectric conversion device that forms the original image, and the case 6 that supports these components. A document image is read by the image reading unit 1.

On the other hand, the image forming section 2 has a drum-shaped photosensitive member 14 as an example of an image carrier and various elements described below. As the print start key is pressed,
The photoconductor 14 is driven to rotate counterclockwise in FIG.
At this time, the surface of the photoconductor is charged to a predetermined polarity by the charging device 15, and light is modulated from the laser writing unit 16, which is an example of the exposure device, according to the image information read by the image reading unit 1 as described above. The laser beam L is emitted, and the charged surface of the photoconductor is exposed to the laser beam L, whereby an electrostatic latent image is formed on the surface of the photoconductor.
This electrostatic latent image is visualized as a toner image by a developer when passing through the developing device 17, and the toner image is exposed to light by a transfer device 18 located opposite to the photoreceptor 14 as described later. The image is transferred onto the surface of the recording sheet S sent to the transfer section between the body 14 and the transfer device 18. The toner remaining on the photoconductor surface after the transfer of the toner image is removed by the cleaning device 19, and the potential on the photoconductor surface is initialized by a static eliminator (not shown). In this way, the image forming unit 2 forms a recording image corresponding to the image information read by the image reading unit 1 on a recording sheet.

On the other hand, the sheet feeding section 3 of the present embodiment has a sheet feeding tray 20 and a sheet feeding roller 20A for feeding the recording sheets S stacked and stored on the sheet feeding tray 20 one by one. are doing. The recording sheet S sent from the paper feed tray 20 reaches the registration roller pair 21 through the conveyance path, and the registration roller pair 21
The recording sheet S is fed to the transfer section between the photoreceptor 14 and the transfer device 18 at a predetermined timing by the rotation of the recording sheet S.
As described above, the toner image is transferred to the surface. It is also possible to configure so that a recording sheet can be fed to a transfer unit from a manual feed tray (not shown).

The recording sheet S onto which the toner image has been transferred from the surface of the photoconductor is further conveyed upward, passes through a fixing device 22 disposed above elements such as the photoconductor 14 constituting the image forming unit 2, and the like. At this time, the toner image is fixed on the surface of the recording sheet S by the action of heat and pressure. The recording sheet S that has passed through the fixing device 22 is discharged to the sheet stacking unit 4 and stacked here, as indicated by an arrow Q. The sheet stacking section 4 has a sheet stacking tray 23 formed by a part of the apparatus housing 5, and a recording sheet is stacked on the tray 23.

Here, as shown in FIG. 2, the image forming apparatus main body side facing the operator who operates the image forming apparatus, that is, the side on which the operation unit 24 is generally provided is a front side Fr of the image forming apparatus main body. The opposite side is the back side R. The direction orthogonal to the front and rear directions is the width direction W of the image forming apparatus main body.

As can be seen from FIG. 2, the sheet stacking area A1 on the front side Fr of the image forming apparatus main body and the sheet stacking area A2 on one end side in the width direction W of the image forming apparatus main body.
Is open. On the other hand, a sheet stacking area A3 on the other end side in the image forming apparatus main body width direction W,
The sheet stacking area on the back side is closed by the apparatus housing 5. As can be seen from FIG. 1, the recorded recording sheet that has passed through the fixing device 22 is discharged to the sheet stacking unit 4 from the discharge unit at the other end in the width direction W of the image forming apparatus main body. The recording sheet is discharged to the sheet stacking unit 4 from the end opposite to the opened sheet stacking unit area A2.

As described above, the sheet stacking section 4 is disposed between the image reading section 1 and the image forming section 2, and the recording sheets are discharged into the body and stacked on the sheet stacking section 4, so that the image forming operation is performed. The overall structure of the image forming apparatus can be reduced in size and the image forming apparatus can be arranged in a small space, compared to an image forming apparatus that discharges recording sheets onto a sheet discharge tray that protrudes greatly to the side of the apparatus main body. Moreover, the area A1 on the near side of the sheet stacking section 4 and the area A2 on one end side
Are open, the recording sheet on the sheet stacking tray 23 of the sheet stacking section 4 can be easily taken out by hand.

FIG. 3 is a simplified perspective view showing the case 6 of the image reading section 1 and the main body base 25 (not shown in FIG. 1). In FIG. The illustration is omitted. The main body base 25 includes a bottom wall 25A and a side wall 2A.
5B, and various elements of the image forming apparatus are supported on the bottom wall. In the example shown, the image forming unit 2 shown in FIG.
The various components such as the photoreceptor 14 and the laser writing unit 16, the fixing device 22, the drive unit 27, and the like are supported by the main body base 25 directly or via other supporting elements. The main body base 25 is made of, for example, a resin molded product.

The drive unit 27 has a casing 28
It has a motor and gears (not shown) housed therein, and drives the photoconductor 14 and the fixing device 22. The drive unit 27 is such that its casing 28 is
Is fixed, for example, by screws.

The paper feed tray 20 shown in FIG. 1 is detachably mounted in the space S1 below the bottom wall 25A of the main body base 25, and the recording paper sent from the paper feed tray 20 is mounted on the bottom wall 25A. An opening 26 through which the sheet S passes is formed.

The case 6 of the image reading section 1 is also fixedly supported on the main body base 25 as follows, for example.

As shown in FIG. 3, mounting holes 29A to 29D are formed in the bottom wall 6A of the case 6, and the side walls 6B
Also, mounting holes 29E and 29F are formed respectively. On the other hand, the main body base 25 has a column 30 located on the bottom side of the back side R and one end side E1 in the width direction, and the column 30 protrudes upward from the bottom wall 25A. The strut 30 is formed integrally with the bottom wall 25A or is fixed to the bottom wall 25A by fixing means (not shown).
A stay 31, which will be described in detail later, is fixed to the column 30.

The body base 25 has a front side F
A stud 32 protruding upward is fixed to a portion r and at the other end E2 in the width direction.

The stud 32, the casing 28 of the drive unit 27, the upper surfaces of the columns 30, and the stay 31
Mounting holes 33A to 33F are respectively formed. To fix the case 6 to the main body base 25, the bottom wall 6A of the case 6 is placed on the upper surfaces of the studs 32, the drive unit 27 and the columns 30, and the side wall 6B is attached to the mounting surface 31A of the stay 31.
To the mounting holes 29A to 29A formed in the case 6.
F is matched with the mounting holes 33A to 33F formed in the stud 32, the casing 28, the support 30 and the stay 31, respectively, and the case 6 is temporarily placed. Then, as shown by arrows A to F in FIG. 3, screws 34A to 34F are screwed into the matching mounting holes, respectively, to
Is fixed to the main body base 25. Thereby, Case 6
Is fixedly supported on the main body base 25 via a stay 31, a drive unit 27, and a stud 32, and is also fixed to a support 30 thereof.

As described above, the portion of the case 6 of the image reading section 1 on one end side E1 in the width direction W of the image forming apparatus main body, that is, the side wall 6B in the example shown in FIG.
Is fixedly supported by a stay 31 fixed to the column 30.
The stay 31 is formed in a cantilever shape protruding from a fixing portion 31B fixed to the support 30 of the main body base 25 to the front side Fr of the image forming apparatus main body, and the protruding portion 31C
Since the case 6 is fixed to the mounting surface 31A, the case portion on one end side E1 can be firmly supported.
The case corner portion 3 on the front side Fr of the image forming apparatus main body and at one end side E1 in the width direction W of the image forming apparatus main body.
5 is not supported from below the case by the main body base 25, but by supporting the case 6 to the main body base 25 via the stay 31 as described above, the corner 35 of the case 6 A large downward displacement due to its own weight can be prevented.

As described above, the sheet stacking area A1 on the front side Fr of the image forming apparatus main body and the sheet stacking area A2 on one end E1 in the width direction W of the image forming apparatus main body are open. Thus, the case 6 of the image reading unit 1 is fixedly supported on the main body base 25.

The stay 31 of this embodiment is a separate member from the column 30, and the stay 31 is configured to be fixed to the column 30 by screws as described later. The stay 31 is formed integrally with the column 30,
These may be configured as one member. The stay 31 can be formed as a molded product integral with the main body base 25.

As described above, when the case 6 is placed on the casing 28, the stud 32, and the upper surface of the column 30, and the case 6 is temporarily placed with the side wall 6B of the case 6 aligned with the mounting surface 31A of the stay 31. Since the casing 28, the stud 32, and the case portion placed on the support 30 are supported from below by the casing 28, the stud 32, and the support 30, the case portion can be held at an appropriate height. it can.

However, in the case of only the above-described configuration, since the side wall 6B of the case 6 only faces the mounting surface 31A of the stay 31, the case 6 is not supported from below by the stay 31. Corner 35 of the image reading unit 1 is lowered by its own weight. If the case 6 is fixed to the main body base 25 with the screws 34A to 34F in this state as described above, the case 6 is fixed to the main body base 25 in a twisted state.

Therefore, as shown in FIGS. 3 and 4, the stay 31 is provided with a support portion 36 for supporting the case 6 from below before fixing the case 6 to the stay 31. In the example shown in the drawing, a support portion 36 is formed by a projection integrally provided on a portion 31C of the stay 31, and the support portion 36 engages with a notch 37 formed in the case 6 to lower the case 6. And the height position of the case 6 is regulated. The support portion 36 is provided at a position closer to the free end side of the stay 31 than the fixing portion 31B of the stay 31. Therefore, the support portion 36 supports the corner portion 35 of the case 6 or a portion in the vicinity thereof from below. be able to.

As described above, the case 6 is connected to the main body base 25.
When the case 6 is temporarily placed, the case 6 is supported from below by the support portion 36, so that the case 6 is deformed in a direction in which the corner portion 35 of the case 6 is greatly lowered downward by the weight of the image reading portion 1. Can be blocked. Therefore,
If the case 6 is fixed to the main body base 25 with screws in this state, the entire image reading unit 1 can be held horizontally at an appropriate height. In this manner, the image reading unit 1 can correctly read a document image and form a high-quality recording image on a recording sheet.

As described above, the height position of the case 6 can be regulated by the support portion 36. However, as described above, the support portion 36 of the present embodiment is more free of the stay 31 than the fixing portion 31B of the stay 31 as described above. When the case 6 is placed on the support portion 36, the stay 31 itself is moved by the arrow G in FIG.
Slightly elastically deform in the direction shown by.

Therefore, in the image forming apparatus of this embodiment,
The height H from the bottom wall 25A to the support portion 36 before the case 6 is mounted on the support portion 36 is set to a value higher than the appropriate height in consideration of the deformation amount of the stay 31 generated when the case 6 is mounted on the support portion 36. Is also set slightly larger. With this configuration, when the stay 31 is deformed due to the weight of the image reading unit 1, the support unit 36 has an appropriate height, and the assembled case 6 of the image reading unit 1 can be held in a horizontal state. For example, the height H of the support portion 36 before the case 6 is placed thereon
Is set 0.45 mm higher than the appropriate height.

As described above, the height H of the support portion 36 before the case 6 is mounted on the support portion 36 is set to an appropriate height from the bottom wall 25A of the support portion 36 after the image reading section 1 is assembled. By setting the size to allow for the amount of deformation of the stay 31 so that the case 6 is twisted, it is possible to more reliably remove the problem that the case 6 is attached in a twisted state, and to obtain a high-quality recorded image.

FIG. 5 shows a state before the stay 31 is fixed to the column 30, and FIG. 6 shows a state after the stay 31 is fixed to the column 30. In the example shown in these figures, the screw 38 is inserted into the mounting hole 39 formed in the fixing portion 31B of the stay 31 and is screwed into the screw hole 40 formed in the support 30 to be tightened. Is fixed to the column 30 of the main body base 25. At this time, as is apparent from FIG.
0 is formed with a screw hole 40 at the bottom of the groove 41.
Is formed, and the screw 38 is screwed into the bottom of the groove 41.

As shown in FIG. 7, without forming a groove in the main body base 25, the column 30 of the main body base 25 and the stay 3
1 may be fixed by the screw 38. In this case, the stay portion 42 near the screw 38 strongly presses against the surface of the column 30, but the stay portion 4 away from the screw 38 is pressed.
The pressing force between the support 3 and the support 30 is weakened, and a minute gap may be formed between them. When this happens, stay 3
The frictional force generated between the support 1 and the support 30 is reduced, and the stay 3
Most of the load applied to 1 acts on the screw 38, and the screw 38 may be deformed, and the stay 31 may be slightly displaced downward.

On the other hand, when a groove 41 is formed in the main body base 25 as shown in FIG.
When the screw 8 is screwed in and tightened, the tightening force of the screw is distributed over the entire contact surface between the stay 31 and the column 30, and these members come into close contact with each other over the entire contact surface and come into strong frictional engagement. For this reason, the stay 31 is supported by the entire contact surface with the support 30, and the load applied to the screw 38 is smaller than that in the case of FIG. 7. Thereby, the deformation of the screw 38 can be prevented, the inconvenience that the stay 31 is displaced downward can be prevented, and the original image can be correctly read while the image reading section 1 is always kept horizontal.

When the groove 41 is provided as described above, the stay 3
On the other hand, as shown in FIG. 8, when the screw 38 is strongly tightened, the stay 31 may be deformed so as to largely enter the groove 41 by the force, as shown in FIG. Then, the support stability of the stay 31 is rather deteriorated.

Therefore, as shown in FIG. 9, when the screw 38 is tightened, the stay portion 44 facing the bottom surface of the groove 41 is formed.
Preferably, the groove depth d is set so that the stay portion 44 is elastically deformed and the stay portion 44 and the bottom surface of the groove 41 come into contact with each other. The depth d is, for example, about 0.5 mm. With this configuration, even when the screw 38 is strongly tightened, when the stay portion 44 is deformed to some extent, the stay portion 44 abuts on the bottom surface of the groove 41, so that the stay portion 44 is further deformed. However, it is possible to prevent the support stability of the stay 31 from deteriorating.

Similarly, as shown in FIG. 10, the stay portion 44 facing the groove 41 is formed with a projection 45 which is housed in the groove 41 and protrudes toward the bottom surface of the groove 41, and is provided with a screw 38. The depth of the groove 41 may be set so that the protrusion 45 comes into contact with the bottom surface of the groove 41 when is strongly tightened. The space between the protrusion 45 and the bottom surface of the groove 41 when the stay portion 44 is not deformed is set to, for example, about 0.5 mm in this case as well. Also with this configuration, when the screw 38 is strongly tightened, the projection 45 abuts against the bottom surface of the groove 41, so that the stay portion 44 of the stay 31 is not excessively deformed, and the support stability of the stay 31 is deteriorated. Can be prevented.

The present invention can be widely applied to image forming apparatuses other than the multifunction peripherals, for example, image forming apparatuses such as a digital copying machine, a printer, a facsimile, and a printing machine.

[0047]

According to the first aspect of the present invention, it is possible to prevent the image reading section from being deformed into a greatly twisted state, thereby reading a document image correctly and forming a high quality recorded image. .

According to the second to fifth aspects of the present invention, the above effects can be further ensured.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of an image forming apparatus.

FIG. 2 is an external perspective view of the image forming apparatus.

FIG. 3 is a simplified perspective view illustrating a case of a main body base and an image reading unit.

FIG. 4 is a perspective view of a support portion and a case partially cut away.

FIG. 5 is a perspective view showing a state before the stay is fixed to a column of the main body base.

FIG. 6 is a cross-sectional view showing a state where the stay is fixed to a support.

FIG. 7 is a cross-sectional view when a stay is fixed to a column on which a groove is not formed.

FIG. 8 is a cross-sectional view showing a state where a stay portion facing a groove is excessively deformed when a screw is tightened.

FIG. 9 is a cross-sectional view showing a state in which a stay portion is in contact with the bottom surface of the groove when the screw is tightened.

FIG. 10 is a cross-sectional view illustrating an example in which a stay is provided with a protrusion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading part 2 Image forming part 4 Sheet loading part 6 Case 25 Main body base 31 Stay 31B Fixed part 36 Support part 38 Screw 41 Groove 44 Stay part 45 Projection A1 Sheet loading part area A2 Sheet loading part area d Depth E1 One side End side Fr Image forming apparatus main body front side H Height S Recording sheet W Image forming apparatus main body width direction

Claims (5)

[Claims] 1. An image reading section for reading a document image, and an image forming section for forming a recorded image on a recording sheet, wherein the image forming section is arranged below the image reading section, and the image reading section A sheet stacking unit for stacking a recording sheet on which a recording image is formed by the image forming unit is disposed between the image forming unit and the image forming unit; An image forming apparatus in which a case of the image reading unit is fixedly supported on a main body base in a state where a sheet stacking region on one end side in a main body width direction is opened, wherein an image of the case of the image reading unit is provided. A portion on one end side in the width direction of the forming apparatus main body is fixedly supported by a stay fixed to the main body base, and the stay protrudes from the fixing portion fixed to the main body base toward the image forming apparatus main body front side. Formed in a cantilever shape Rutotomoni, to the stays, an image forming apparatus, wherein the supporting portion for supporting the casing prior to fixing the case to the stay from below is provided. 2. The support portion is provided at a position closer to a free end side of the stay than a fixing portion of the stay, and the height of the support portion before the case is placed on the support portion is the height of the image. The image forming apparatus according to claim 1, wherein the size of the stay is set in consideration of a deformation amount of the stay so that the height of the support unit after the reading unit is assembled is an appropriate height. 3. The image forming apparatus according to claim 1, wherein the stay is fixed to the main body base by a screw, and the screw is screwed into a bottom of a groove formed in the main body base. 4. The depth of the groove is set such that when the screw is tightened, a stay portion facing the bottom surface of the groove is elastically deformed, and the stay portion contacts the bottom surface of the groove. The image forming apparatus according to claim 3. 5. A stay portion facing a bottom surface of the groove,
A protrusion that is housed in the groove and protrudes toward the bottom surface of the groove is formed, and the depth of the groove is set so that the protrusion contacts the bottom surface of the groove when the screw is tightened. The image forming apparatus according to claim 3, wherein: