JP2003087462A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can realize space saving without compromising visibility of a discharged sheet and extraction operability even in the case that a sheet discharge section is formed above an image read section. SOLUTION: The image forming apparatus is characterized in that it includes; an image read section 1 for reading an image, an image forming section 2 disposed under the image read section 1 to form an image on a sheet; a sheet discharge space 3 disposed in an apparatus enclosure 41 between the image read section 1 and the image forming section 2; and a sheet discharge section 22 disposed above the image read section 1, and at least part of the image read section 1 is configured movable to the sheet discharge space 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having an image reading unit for reading an image and an image forming unit for forming an image on a sheet.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus having an original image reading section such as a copying machine or a facsimile apparatus has an image reading section arranged at an upper portion of the apparatus and an image forming section provided below the image reading section, and an image is formed by the image forming section. In general, the formed recording sheet is discharged and stacked outside the side surface of the apparatus.

However, in recent years, for the purpose of space saving, as shown in FIG. 13, a space 103 is provided between the image reading portion 101 and the image forming portion 102, and there is a device for discharging and stacking recording sheets in this space 103. .

In the image reading unit 101, an original sent from an automatic original feeding device (hereinafter referred to as "ADF") 109 arranged above the image reading unit 101 is exposed and scanned to take in image information into a photoelectric conversion element and perform data processing. .

Based on the data, the laser scanner 104 scans the photosensitive drum 105 to form a latent image. The toner image developed on the photosensitive drum 105 according to the latent image is transferred onto the sheet fed and fed from the feeding cassette 106, passes through the fixing device 107 and is fixed on the sheet, and is discharged by the discharge roller 108. It is discharged and loaded in the discharge space 103.

[0006]

In the above image forming apparatus, when post-processing such as punching processing and stapling processing is performed on an image-recorded sheet, as shown in FIG. The apparatus 109 is connected, and the sheet is fed into the sheet processing apparatus 109 to perform stapling processing or the like.

However, the sheet processing apparatus is provided on the side of the apparatus.
Connecting 109 will require a large installation space. If this space is made small, the structure of the device becomes complicated and the operability of taking out the sheet becomes poor.

The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus capable of realizing space saving of the apparatus without impairing the visibility and operability of taking out a discharge sheet. Is.

[0009]

A typical structure according to the present invention for achieving the above object is an image reading section for reading an image and an image reading section arranged below the image reading section to form an image on a sheet. An image forming unit; a sheet discharging space provided inside the apparatus housing between the image reading unit and the image forming unit; and a sheet discharging unit provided above the image reading unit, At least a part of the image reading unit is configured to be movable into the sheet discharge space.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is an overall cross-sectional explanatory view of an image forming apparatus according to a first embodiment.

{Overall Structure of Image Forming Apparatus} This image forming apparatus has an image reading section 1 which is an image reading section and an image forming section 2 which is an image forming section, and an image is read above the image forming section 2. The part 1 is arranged. An ejecting space 3 for ejecting the sheet recorded by the image forming unit 2 is formed in the apparatus housing between the two, which is a so-called in-machine ejecting type image forming apparatus. Further, above the image forming unit 2, there is provided a sheet processing apparatus that performs processing such as punching and stapling on an image-formed sheet.

In the image reading section 1 of this embodiment, an ADF 4b is mounted on a scanning optical system 4a for optically reading an original, and the original sent from the ADF 4b onto the platen glass 5 or the scanning optical system 4a is read. The scanning optical system 4a scans the original set on the platen glass 5 by rotating downward to open it.
It is read by scanning with exposure.
That is, the image reading unit 1 irradiates the document on the platen glass 5 with light while scanning the light source 6, and collects the reflected light on the photoelectric conversion element 9 via the mirror 7 and the lens 8.
It is converted into an electrical digital signal and transmitted. If this digital signal is transmitted to its own image forming section 2, it functions as a copying machine, and if it is transmitted to the image forming section of another machine, it functions as a facsimile machine.

The image reading section 1 is not necessarily the ADF.
4b may not be attached. That is, the scanning optical system 4a
An original pressing member for pressing the original set on the platen glass 5 may be provided.

The image forming section 2 uses an electrophotographic toner image on the sheet conveyed by the sheet feeding roller 12 and the conveying roller 13 from the sheet cassette 11 loaded in the sheet feeding section 10 disposed below the image forming section 2. Is formed. That is, the photosensitive drum rotating in the direction of the arrow in FIG.
The surface of 14 is uniformly charged by a charging roller 15, and the photosensitive drum 14 is selectively exposed by a laser scanner 16 which irradiates light based on image information transmitted from the image reading section 1 or a personal computer. By doing so, a latent image is formed. This latent image is visualized by developing the toner with the developing device 17,
The toner image is transferred to the conveyed sheet by applying a bias to the transfer roller 18.

The sheet on which the toner image has been transferred as described above is conveyed as it is to the fixing device 19 located above,
Here, heat and pressure are applied to fix the toner, and then the toner is discharged to a predetermined discharge portion.

That is, the sheet that has passed through the fixing device 19 is
By rotating the first switching flapper 20 around the fulcrum 20a, the first switching flapper 20 is selected and conveyed in the direction of arrow a or arrow b (FIG. 1 shows the state in which the direction of arrow b is selected).

The selection of the conveying directions a and b is determined by the operator selecting the ejecting section in advance, and the ejecting section is selected for each job from the operation section of the apparatus or a personal computer. Although it may be performed, it may be set in advance depending on the type and content of the job.

For example, in the case of a facsimile output which is rarely used, the paper is always discharged from the discharge roller 21 to the discharge space 3, and the conveying direction is set to the direction of arrow a. on the other hand,
In the case of a copy or printer job that requires sorting, a plurality of discharge trays 23 provided in the discharge unit 22 located above the image reading unit 1 are selected and set in the direction of arrow b.

Further, even in copy jobs, sorting is unnecessary.
In the case of copy copy, it is possible to set the discharge space 3 as the discharge destination in order to shorten the output time.

{Sheet Processing Apparatus} Next, the configuration of the sheet processing apparatus for performing the punching process and the stapling process in this embodiment will be described with reference to FIGS.
The sheet processing apparatus according to the present embodiment carries the image-formed sheets into an intermediate processing tray 31 having a substantially vertical stacking surface, aligns them into a sheet bundle, staples them, and then discharges them to an upper discharging section. To do. 2 is a cross-sectional explanatory view of the sheet processing unit when the sheet post-processing is not performed, and FIG. 3 is a cross-sectional explanatory view of the sheet processing unit when the intermediate processing is performed.

(Conveying means) The sheet conveyed in the direction of arrow b in FIG. 1 by the first switching flapper 20 is next switched in the conveying direction by the second switching flapper 24 depending on the presence or absence of post-processing.

That is, in the case of a job that does not require sheet processing such as binding and punching, the second switching flapper 24 rotates about the fulcrum 25 to the position shown in FIG. At this time, the bundle discharge roller 26a is supported by a swing guide 28 that swings as a fulcrum 27, and rotates to the position shown in FIG.

The sheet is conveyed by a first conveying roller pair 29 and a second conveying roller pair 30 as conveying means to a bundle discharge roller pair 26a, 26b located substantially vertically above and substantially vertically above the image forming section 2. The sheets are discharged and stacked on the discharge tray 23 located at.

Next, in the case of a job that requires sheet processing, the second switching flapper 24 rotates about the fulcrum 25 to the position shown by the solid line in FIG.
Is loaded in the direction. At this time, the swing guide 28 supporting the bundle discharge roller 26a rotates around the fulcrum 27 and separates from the bundle discharge roller 26b, and is shown in FIG. 3 during the sheet loading onto the intermediate processing tray 31 and the post-processing. Retracted to the position.

Since the bundle discharge roller 26a is retracted in this manner, even large-sized sheets whose leading edge exceeds the bundle discharge roller 26b at the time of alignment and post-processing in the intermediate processing tray 31 are also stored in the intermediate processing tray 31. The post-processing operation of is possible.

Thereafter, when the trailing edge of the sheet P passes through the first conveying roller pair 29, the second switching flapper 24 is switched to the position shown by the chain double-dashed line in FIG. Be guided in the direction. At this time, the first conveying roller pair 29 is set to a rotation speed sufficient to kick out the rear end of the sheet P.

(Sheet Processing Section) The sheet P carried into the intermediate processing tray 31 is held in a substantially vertical state and aligned as shown in FIG. 3, and stapled by the stapling unit 60 provided at the lower end. Is done. for that reason,
As shown in FIG. 4, the intermediate processing tray 31 is provided with alignment means for aligning the sheet width in the front / back direction of the apparatus each time a sheet is stacked. Note that FIG. 4 is an explanatory diagram of the aligning unit in which the sheet width direction (the direction orthogonal to the sheet conveying direction) is shown in the vertical direction.

As shown in FIG. 4, the alignment means aligns the front alignment plate 32a and the rear alignment plate for aligning the front side (front side in FIG. 1) and the back side (back side in FIG. 1) in the sheet width direction. A plate 32b is arranged. The front matching plate 32a and the rear matching plate
32b is provided integrally with the width matching racks 33a and 33b so as to be reciprocally movable in the vertical direction of FIG.
a and a rear aligning plate 32b, which are provided integrally with each other
It is configured to reciprocate in the left-right direction in FIG. 4 by the bundling motors 35a and 35b provided on the width-matching racks 33a and 33b.

The width matching racks 33a and 33b are intermediate processing trays.
The sheet 31 is reciprocally mounted in the sheet width direction, and is configured to reciprocate in the sheet width direction by the width matching motors 36a and 36b.

At the lower ends (right ends in FIG. 4) of the front and rear matching plates 32a and 32b, there is provided an abutting reference wall 37 which serves as a reference at the time of post-processing. However, a part of the abutting reference wall 37 may be fixed to the intermediate processing tray 31.

The intermediate processing tray 31 is carried in,
A stapling unit 60 for stapling the sheet bundle aligned in the sheet width direction by the aligning unit is provided. The stapling unit 60 is driven in the direction of arrows f and e in FIG. It is configured to move and operate, and is movably provided so as not to block the conveyance path of the sheet bundle.

Sheet P carried into the intermediate processing tray 31
As shown in FIG. 3, the sheets are stacked by abutting against the abutting reference wall 37 located at the lower end of the intermediate processing tray by its own weight. In the present embodiment, the abutting reference walls 37 are provided at the lower ends of the front and rear alignment plates 32a and 32b, respectively.
The space between 32a and 32b is wider than the width of the sheet to be loaded,
In addition, it is set to stand by at the standby position where the lower end of the sheet dropped on the intermediate processing tray 31 by its own weight can be supported by the front and rear abutting reference walls 37.

Further, as shown in FIG. 3, the end portion of the abutting reference wall 37 is formed so as to stand up so that the abutting sheet P does not slip and fall, and is formed to have a U-shaped cross section. There is.

When the lower end of the sheet falls on the intermediate processing tray 31 and hits the abutting reference wall 37, the width aligning motors 36a and 36b.
Is transmitted to the width aligning racks 33a and 33b, and the front aligning plate 32a and the rear aligning plate 32b move in the sheet width direction to align in the sheet width direction. When the alignment is completed, the front aligning plate 32a and the rear aligning plate 32b return to the standby position. The sheets sequentially discharged in this manner are aligned one by one as described above, and a predetermined number of sheets are stacked on the intermediate processing tray 31 to form a bundle.

The aligned sheet bundle is stapled by the staple unit 60 when, for example, staple processing is instructed by the operation unit.
The staple is driven by and stapled. When the post-processing such as stapling is completed, as shown in FIGS. 5 and 6, the front aligning plate 32a and the rear aligning plate 32b are pushed upward by driving the bundle delivering racks 34a, 34b and the bundle delivering motors 35a, 35b. The post-processed sheet bundle P'is formed by the reference wall 37 formed integrally with the alignment plates 32a and 32b.
The sheet is conveyed at least until its tip reaches the bundle discharge roller pair 26a, 26b.

When the front end of the sheet bundle P'has passed the bundle discharge roller 26b, the swing guide 28 is pressed to the position shown by the chain double-dashed line in FIG.
The sheet bundle P ′ is discharged to the discharge tray 23 by b.

Thereafter, the front aligning plate 32a and the rear aligning plate 32b move downward due to the reverse rotation of the bundling motors 35a and 35b, and when the position sensor (not shown) detects that they have descended to a predetermined position, the bundling is performed. The driving of the motors 35a and 35b is stopped to prepare for the post-processing of the next job.

(Sheet discharging section)

Further, as shown in FIG. 1, the discharge tray 23 provided above the image reading section 1 in the present embodiment is
A plurality of lead cams 38 with a spiral groove are arranged in a lateral direction (a direction intersecting the sheet discharge direction, which is the horizontal direction in the present embodiment) in a state of standing upright, and are rotated in the arrow c direction by the drive source 61. And a guide rail 39a provided on a rear side plate 39 which supports the rear side of the discharge tray 23, moves in the left-right direction.

That is, rollers 40 that engage with the grooves of the lead cam 38 are provided at the lower ends of the front and rear ends of each discharge tray 23, and the rotation of the lead cam 38 allows the discharge tray 23 to move laterally. . Then, the tray position is detected by a position detection sensor (not shown) and the tray is stopped at a predetermined position, so that the sheets discharged by the bundle discharge roller pair 26a, 26b or the sheet bundle is discharged to a predetermined discharge tray 23.

In the case of the sort mode, the above-mentioned discharge is performed in such a manner that the discharge trays 23 are sequentially moved as the sheets are discharged, and the sheets are discharged to the plurality of discharge trays 23 in a sorted state. On the other hand, in the non-sort mode, the rightmost discharge tray 23 shown in FIG. 1 moves to a position for receiving discharged sheets, and the sheets are discharged to the tray.

Since the discharged sheet is supported by the discharge tray 23, the discharged sheet is in an upright state, and does not require a horizontal discharge space even if the sheet size is large.

(Movement of Image Reading Unit) In this embodiment, since the discharge tray 23 is arranged above the image reading unit 1 as described above, the original pressure plate and the ADF 4 are arranged as in the conventional case.
If b is opened upward, the structure becomes complicated. Therefore, in the present embodiment, as shown in FIG. 7, the image reading unit 1 can be moved to the discharge space unit 3 (moved in the direction of arrow d in FIG. 1). 7. FIG. 7 is a side view of the main body of the image forming apparatus according to the present embodiment as viewed from the left side.

As shown in FIG. 7, the ADF 4b is a device housing.
The image reading unit 1 fixed to 41 and provided with the scanning optical system 4a is configured such that the portion of the scanning optical system 4a is rotatable with respect to the ADF 4b with the rotary hinge 42 as a fulcrum. It is pulled up and fixed to the position shown in FIG. 7 (a) by 43.

The operator operates the platen glass 5 of the image reading unit 1.
When a document is placed on the document and the image is read, when the handle 44 provided on the front side of the scanning optical system 4a is pushed down, as shown in FIG. 7 (b), the rotary hinge 42 is centered. The portion of the scanning optical system 4a is rotationally moved to the area of the discharge space portion 3, and the platen glass 5 is exposed. In this state, the original is set according to the abutting reference 5a formed on the platen glass 5 on the front side of the apparatus.

When the scanning optical system 4a is returned by holding the handle 44, the scanning optical system 4a is pulled by the tension force of the tension spring 43.
As shown in FIG. 7A, the ADF 4b is pressed, and scanning reading is performed in this state.

The rotary hinge portion 42 is movable within a vertically elongated hole 45 formed in the apparatus casing 41, and is biased to the upper edge side of the vertically elongated hole 45 by a compression spring 46.
Therefore, as shown in FIG. 8, when a thick book document G is set on the platen glass 5, the compression spring 46 provided on the rotary hinge portion 42 of the image reading unit 1 contracts so that the thick document becomes parallel. It is configured to be pressed against.

As described above, by making the image reading section 1 movable to the area of the discharge space section 3, the original can be set without moving the discharge tray 23 arranged above the image reading section 1. . Therefore, it is possible to save the space of the apparatus without impairing the visibility and the operability of taking out the sheet discharged onto the discharge tray 23.

[Second Embodiment] FIG. 9 is a diagram illustrating the configuration of another movement mode of the image reading unit according to the second embodiment. The configuration other than the moving configuration of the image reading unit 1 is the same as the first configuration described above.
It is similar to the embodiment.

In the moving configuration of the image reading section 1 according to FIG. 9, the tension force of the tension spring 43 connecting the scanning optical system 4a and the ADF 4b is set to be weaker than that of the first embodiment, and the scanning optical system 4a is The tension spring 43 functions as a damper at that time because it rotates by its own weight and pulls down.

A fulcrum 47 is provided on the side surface of the scanning optical system 4a.
A lock member 48 that is rotatable around is attached. Hook portions 48a are formed on the upper and lower ends of the lock member 48, and the hook portions 48a are respectively formed in the discharge space portion 3.
It is possible to engage with an engaging portion 49 formed on the bottom surface of the ADF 4b and an engaging portion 50 provided on the side surface of the ADF 4b.

Therefore, as shown in FIG. 9A, when the scanning optical system 4a is closed, the upper hook portion 48a is attached to the ADF 4b.
It is locked and fixed to the locking portion 50 of. On the other hand, as shown in FIG. 9B, when the scanning optical system 4a is opened, the lower hook portion 48
A is locked to the locking portion 49 and fixed.

By making the tension spring 43 function as a damper as described above, it is possible to smoothly open and close the scanning optical system 4a.

[Third Embodiment] FIG. 10 is a diagram illustrating the configuration of another movement mode of the image reading unit according to the third embodiment. Note that, in this embodiment as well, the configuration other than the moving configuration of the image reading unit is the same as that of the first embodiment described above.

The moving configuration of the image reading section 1 according to FIG. 10 shows a mode in which the scanning optical system 4a moves up and down in parallel, and the operator may manually move the scanning optical system 4a. The drive motor 51 is configured to vertically move an L-shaped frame 52 with a rack formed integrally with the scanning optical system 4a.

That is, the guide roller 53 attached to the frame 52 is configured to be movable up and down with respect to the apparatus casing 41, and the motor 51 is operated by a switch operation provided on the operation unit or in the vicinity of the image reading unit. The scanning optical system 4a is driven to move from the state shown in FIG. 10A to the state shown in FIG. 10B, and the platen glass 5 is opened. After setting the original, the scanning optical system 4a is raised by rotating the motor 51 in the reverse direction,
The home sensor 54 detects the position and stops.

The ADF 4b or the original pressure plate is configured to be movable up and down with respect to the apparatus housing 41 by a guide rail 55, and when the scanning optical system 4a is raised to a predetermined position, the ADF 4b is moved to the compression spring 56. Against it goes up and crimps the original. Therefore, as shown in FIG. 11, even when a thick document G is set, the document is brought into close contact with the platen glass 5.

[Fourth Embodiment] FIG. 12 is a diagram illustrating the configuration of another movement mode of the image reading unit according to the fourth embodiment. Note that, in this embodiment as well, the configuration other than the moving configuration of the image reading unit is the same as that of the first embodiment described above.

In this embodiment, the scanning optical system 4a and the ADF 4 are used.
In the example shown in FIG. 3B, the scanning optical system 4a can move up and down in the discharge space 3 with the same configuration as that of the third embodiment. The ADF 4b is rotatable with respect to the optical system 4a by the same configuration as that of the first embodiment.

Therefore, when setting the book original G, as shown by the broken line in FIG. 12, it is set in the same manner as described in the first embodiment. Then, the image reading is performed while the image reading unit 1 is moved downward of the discharge space unit 3, and after the image reading is finished, the discharge space unit 3 is opened. To rise.

Other Embodiments In the above-described embodiment, the image reading unit 1 has the scanning optical system 4a and the ADF 4b, and the scanning optical system 4a is movable to the area of the discharge space 3. The scanning optical system 4a may be fixed and the ADF 4b may be movable in the area of the discharge space 3.

[0063]

As described above, according to the present invention, by providing the mechanism for lowering the image reading unit into the discharge space, even if the sheet discharging unit is provided above the image reading unit, the discharge unit can be removed. There is no need to push it up, without compromising the visibility of the discharge sheet and the operability of taking it out.
It is possible to realize sorting of discharge sheets in a small space.

[Brief description of drawings]

FIG. 1 is an overall cross-sectional explanatory diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a cross-sectional explanatory diagram of a sheet processing unit when sheet post-processing is not performed.

FIG. 3 is a cross-sectional explanatory diagram of a sheet processing unit when performing sheet post-processing.

FIG. 4 is an explanatory diagram of a matching unit.

FIG. 5 is an explanatory view showing a state where the intermediate processing tray is moved upward.

FIG. 6 is an explanatory diagram of a state in which the intermediate processing tray is moved upward.

FIG. 7 is a side view illustrating the image forming apparatus main body according to the present embodiment as viewed from the left side surface.

FIG. 8 is an explanatory diagram of a state when a thick original is read.

FIG. 9 is a configuration explanatory diagram of another movement mode of the image reading unit according to the second embodiment.

FIG. 10 is a configuration explanatory diagram of another movement mode of the image reading unit according to the third embodiment.

FIG. 11 is an explanatory diagram of a state when a thick original is read.

FIG. 12 is a configuration explanatory diagram of another movement mode of the image reading unit according to the fourth embodiment.

FIG. 13 is an explanatory diagram of an image forming apparatus according to a conventional technique.

FIG. 14 is an explanatory diagram in which a sheet processing apparatus is connected to a side portion of the apparatus main body.

[Explanation of symbols]

P ... Sheet P '... sheet bundle 1 ... Image reading unit 2 ... Image forming unit 3 ... Discharge space 4a ... Scanning optical system 4b ... ADF 5 ... Platen glass 5a ... Hitting criteria 6 ... Light source 7 ... Mirror 8 ... Lens 9 ... Photoelectric conversion element 10… Sheet feeding section 11… Sheet cassette 12… Feeding roller 13… Conveyor roller 14 ... Photosensitive drum 15… Charging roller 16… Laser scanner 17 ... Developer 18… Transfer roller 19… Fixer 20 ... Switching flapper 20a… fulcrum 21… Ejection roller 22… Ejector 23… Ejection tray 24 ... Switching flapper 25 ... fulcrum 26a, 26b ... Bundle discharge roller 27… fulcrum 28… Swing guide 29, 30… Pair of transport rollers 31… Intermediate processing tray 32a… Front matching plate 32b ... Rear matching plate 33a, 33b ... Width matching rack 34a, 34b ... Bundle rack 35a, 35b ... Bundle motor 36a, 36b ... Width matching motor 37… Abutting reference wall 38… Lead cam 39 ... Rear plate 39a ... Guide rail 40 ... 41… Device housing 42 ... Rotary hinge 43 ... tension spring 44… Handle 45… Vertical hole 46… Compression spring 47… fulcrum 48 ... Lock member 48a ... Hook part 49… Locking part 50 ... Locking part 51… Drive motor 52… Frame 53… Guide roller 54… Home sensor 55… Guide rail 60… Staple unit 61… Drive source

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshimasa Suzuki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Hiromichi Tsujino             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Nasaku Kamiya             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Masaaki Inoo             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Shunsuke Nishimura             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2H071 BA03 BA14 DA02 DA18 DA24                       EA04                 5C062 AA02 AA05 AB17 AB30 AB35                       AD06 BA01

Claims (3)

[Claims] 1. An image reading unit that reads an image, an image forming unit that is disposed below the image reading unit, and forms an image on a sheet, and an apparatus housing between the image reading unit and the image forming unit. A sheet discharge space portion provided and a sheet discharge portion provided above the image reading unit, and at least a part of the image reading unit is configured to be movable into the sheet discharge space. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the image reading unit has an automatic document feeder and a scanning optical system. 3. The image forming apparatus according to claim 2, wherein either one of the automatic document feeder and the scanning optical system is fixed to the main body of the apparatus.