JPH07168407A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image forming apparatus capable of selectively performing double-sided recording can be made compact in the height direction, and a recording paper reconveying unit that functions as a double-sided unit can be easily attached and detached. And an image forming apparatus capable of selectively loading a recording paper reversing unit. [Structure] A recording sheet re-conveying unit 4 and a recording sheet reversing conveying unit 5 are detachably provided to an image forming apparatus main body 10. A device for reversing and conveying the recording paper P ₀ discharged from the image forming unit 1 is fed to the recording paper reversing / conveying unit 5, and the reversing and conveying recording paper P ₀ is fed to the paper reversing unit 22 for the recording paper reconveying unit 4. A paper transport unit is provided.

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 capable of selectively performing double-sided recording.

[0002]

2. Description of the Related Art In an image forming apparatus capable of double-sided recording, a reversing unit for reversing both sides of a recording sheet discharged from an image recording section and an inverted recording sheet for the image recording section are usually used. And a transport unit for transporting again. Conventionally, the reversing unit and the re-conveying unit are integrally configured as, for example, one double-sided unit, and this double-sided unit is provided in the loading area of the sheet feeding cassette.
It was designed so that it could be loaded instead of the paper cassette.

In this type of image forming apparatus, a reversing roller is often used in the reversing section. When a reversing roller having a small diameter is used, when a thick recording sheet is used,
It becomes difficult to smoothly perform the reverse conveyance. Therefore, a reversing roller having a relatively large diameter is used.

If a reversing roller having a large diameter is used in consideration of such a point, the double-sided unit becomes thick and the entire image forming apparatus becomes large in the height direction. Furthermore,
If the double-sided unit is provided with a paper reversing unit, a drive source for transporting recording paper, etc., the unit becomes heavy and it becomes difficult to attach and detach the unit.

An image forming apparatus in which a reversing unit is provided as standard equipment in the main body of the image forming apparatus has also been proposed, but when such an image forming apparatus is used by a user who does not perform double-sided recording, Such an inversion unit is not used at all and is wasted. As a related technique of this kind, for example, Japanese Patent Laid-Open No. 60-88.
61, JP-A-63-208470, JP-A 1-30
8354, JP-A-2-310269, JP-A3-1
Those disclosed in each of Japanese Patent Application Laid-Open Nos. 3967 and 5-66622 have already been proposed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to make an image forming apparatus capable of selectively performing double-sided recording compact in the height direction and to provide a recording paper re-conveying unit which functions as a double-sided unit. An object of the present invention is to provide an image forming apparatus that enables easy attachment / detachment and enables selective loading of a recording paper reversing unit.

[0007]

In order to achieve the above-mentioned object, the present invention comprises an image forming unit having an image recording unit therein, and a paper feeding cassette placed at a lower position of the image forming unit. However, in the image forming apparatus in which the latter paper feed cassette is detachably attached to the image forming apparatus main body, and a paper reversing unit for reversing the recording paper fed from the paper feed cassette is provided in the image forming unit, Like the paper feed cassette, it is detachable from the main body of the image forming apparatus. With the paper feed cassette removed, it is loaded in the mounting area of the paper feed cassette, and one side has already been recorded. A recording paper re-conveying unit for re-conveying the paper to the image recording unit via the paper reversing unit is provided, and the recording paper re-conveying unit is detachable from the image forming apparatus main body independently of the recording paper re-conveying unit. The recording paper reversing and conveying unit that conveys the recording paper discharged from the image forming unit and whose one side has already been recorded and reverses the recording paper, and also returns the recording paper to the recording paper reconveying unit during the conveyance. An image forming apparatus including the above is proposed.

When the recording paper discharge side from the image forming unit is the rear end of the image forming unit, the image forming unit and the paper feeding cassette are rear regions of the rear end of the image forming unit. Both of them are sized and arranged so that a space is formed in the upper region of the rear end portion, and it is advantageous if the recording paper reversal conveyance unit can be arranged in the space region. Target.

The recording sheet reversing / conveying unit has a driving source for conveying the recording sheet and a driving member to which the rotational driving force from the driving source is transmitted. It is effective to have a driven member for carrying the recording paper, which engages with the driving member of the recording paper reversing / conveying unit installed in the main body of the image forming apparatus. is there.

Further, it is effective that the main body of the paper feed cassette and the recording paper re-conveying unit are common case bodies.

Further, it is effective that the recording paper reversing / conveying unit enables the recording paper discharge tray to be attached to the image forming unit.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is of a laser recording type and is also called a laser printer.

The image forming apparatus shown in FIG. 1 is an image forming apparatus equipped with a recording sheet reversing / conveying unit and a recording sheet re-conveying unit, which will be described later, for performing double-sided recording. On the other hand, the image forming apparatus shown in FIG.
Such an image forming apparatus is not equipped with these units, and is hereinafter referred to as a "standard machine". It should be noted that both of the drawings are sectional views, but for convenience, the cross-sectional portions of the respective members are partially left unhatched.

The structure and recording method of this standard machine will be described below.

Reference numeral 1 indicates an image forming unit having an image recording section (which will be described later) inside. At the position below the image forming unit 1, the paper feed cassette 2
Furthermore, another paper feed cassette 3 is provided below this cassette.
Have been deployed respectively. The image forming apparatus of this example is equipped with two paper feed cassettes as a standard machine.

The image forming unit 1 includes a simple paper feed tray 6
The sheet feeding cassette 2 is attached and detached toward the portion of the tray 6. That is, the paper feed cassette 2 is attachable to and detachable from the image forming apparatus main body 10, and when detached from the image forming apparatus main body, it is pulled out in the direction of arrow a. The lower sheet feeding cassette 3 is also pulled out in the same direction. Of course, when loaded, the loading direction is opposite to the arrow a.

Here, in order to explain the basic structure of the image forming unit 1, reference numeral 8 indicates a drum-shaped photosensitive member, and the photosensitive member 8 is rotationally driven in the clockwise direction in the drawing. During this rotation, first, the surface of the photoconductor 8 is uniformly charged by the charging roller 11. Reference numeral 12 denotes a laser optical unit, and a laser beam 13 emitted from this unit performs optical writing scanning on the surface of the photoconductor 1 to form a predetermined electrostatic latent image on the surface. . Next, the electrostatic latent image is visualized as a toner image by the toner T carried and conveyed on the developing roller 14 of the developing device.

Here, a bundle of recording sheets P is housed and stacked in the paper feed cassette 2, and the front half of the bundle of recording sheets P is supported on the sheet receiving member 15 and is illustrated. The leading end side is pressed against the paper feed roller 17 by the push-up arm 16 which is biased by a spring not attached.

From the paper feed cassette 2, the uppermost recording paper P ₀ is fed toward the registration roller pair 23 of the image forming unit 1 by the rotation of the paper feed roller 17. A separation pad member 18 is in contact with the paper feed roller 17, and the recording paper is separated one by one at this contact portion.

While the recording paper P ₀ is being sent toward the registration roller pair 23, the recording paper P ₀ is turned upside down by the guide action of the pair of guide plates 20 and 21. As described above, the image forming unit 1 is provided with the paper reversing unit 22 that reverses the recording paper supplied from the paper feeding cassette.

The recording paper P ₀ sent out from the paper feed cassette 2 passes between the guide plates 20 and 21 and reaches the registration roller pair 23. Here, at a timing, the recording paper is sent between the photoconductor 8 and the transfer roller 24, and the toner image on the photoconductor 8 is transferred onto the recording paper P ₀ during this time. After this transfer, the recording paper passes between the fixing roller 25 and the pressure roller 26 of the fixing device having a heater built therein, and the transferred toner image on the recording paper is fixed there. The transfer roller 24 and the fixing device are the image forming unit 1.
The same applies to the paper discharge roller pair 27 described below. In the present example, the image recording unit described above refers to a transfer unit between the photoconductor 8 and the transfer roller 24.

After fixing, the recording paper is ejected from the paper ejection roller pair 27, passes through the passage 29, and is accommodated in the paper ejection tray section 30 with the image surface facing downward. The reference numeral 33 is a stopper member, and the stopper member 33 is movable in the arrow direction according to the length of the recording paper stored in the tray section 30. Although not shown, a case 60 installed in the image forming unit 1 accommodates electric components such as a power source and a printed board.

As described above, the operator performs various operations toward the simple paper feed tray 6, and the front cover 34 of the image forming unit 1 on the operation side uses the hinge portion 34a as a fulcrum. And can be opened in the direction of arrow b. Paper can be fed from the simple paper feed tray 6, and the recording paper sent from here has a toner image transferred from the photoconductor 8 and is fixed by the fixing device. Then, the recording paper is discharged straight to the recording paper discharge tray 31. At this time, the position of the switching guide member 28 provided adjacent to the paper discharge roller pair 27 is switched so that the recording paper discharged from the roller pair 27 is directed to the tray 31.

The image forming apparatus shown in FIG. 2 is used as a standard machine, while FIG. 1 shows the configuration of the image forming apparatus capable of double-sided recording as an option.

In the figure, reference numeral 4 is a recording sheet re-conveying unit, and this unit 4 is detachable from the image forming apparatus main body 10 like the sheet feeding cassette 2 (FIG. 2). However, with the paper feed cassette 2 removed, it is loaded in the mounting area of this paper feed cassette. That is, the paper feed cassette 2 shown in FIG. 2 is pulled out in the direction of arrow a, and the recording paper reconveying unit 4 prepared in advance is loaded in the position shown in FIG. When executing the double-sided recording mode, the recording sheet re-conveying unit 4 re-conveys a recording sheet, one side of which has been recorded, to the previous transfer section (image recording section) via the sheet reversing section 22. To do. Details of this will be described later.

At the same time as the recording paper re-conveying unit 4 is loaded, the recording paper discharge tray 31 shown in FIG. 2 is removed, and then the recording paper reversing / conveying unit 5 is loaded in the tray deployment area as shown in FIG. set. That is,
The recording paper reversal conveyance unit 5 is connected to the image forming unit 1. Then, the removed recording paper discharge tray 31 is attached to the recording paper inversion conveyance unit 5.

In this state, when the image forming apparatus is set to the operating state, the recording paper from the lower paper feed cassette 3, the simple paper feed tray 6 and other paper feed sections passes through the registration roller pair 23. Then, the toner image on the photoconductor is transferred between the photoconductor 8 and the transfer roller 24, and is transferred onto one surface (upper surface) of the recording paper.

The recording paper reversing / conveying unit 5 is independent of the recording paper re-conveying unit 4 and independently of the image forming apparatus main body 1.
With respect to 0, for example, the recording paper which is detachable in the horizontal direction or the axial direction of the photoconductor 8 and is discharged from the image forming unit 1 in the mounted state and whose one side has been transferred (recorded) is used. In addition to the reverse conveyance, the recording sheet is returned to the recording sheet re-conveying unit 4 while being returned during the conveyance.

As a more detailed explanation of the above points, the recording paper P ₀ discharged from the paper discharge roller pair 27 with the image surface facing upward is guided to the passage 35. That is, when the double-sided recording mode is executed, the position of the switching guide member 28 is switched so that the recording paper ejected from the paper ejection roller pair 27 advances toward the passage 35.

The switching guide members 36 and 37 arranged on the left side of the switching guide member 28 in the figure are also switched to the positions shown in FIG. The recording paper P ₀ passes through the passage 35 toward the reversing roller 38 provided in the recording paper reversing / conveying unit 5, and the roller 38 is initially directed in the direction of the solid arrow shown in the figure (counterclockwise direction). It is driven to rotate. By this rotation, the recording paper is turned over to the reverse path 39
Of the recording paper re-conveying unit 5 and then exits from the discharge port 5A of the recording paper reversing / conveying unit 5 and passes through the entrance-side passage 40 of the recording paper re-conveying unit 4.
Enter the passage 41.

Around the reversing roller 38, there are provided guide rollers 44 and 45 which rotate following this rotation, and when the trailing edge of the recording paper reaches between the reversing roller 38 and the guide roller 44. , The reversing roller 38 is once stopped,
After that, the reversing roller 38 is rotationally driven in the direction of the broken line arrow (clockwise direction). Then, the recording sheet that has been reversed and conveyed and has entered the first path 41 is returned, and this time, the trailing end portion up to now is passed through the path 43 and the second path inside the recording sheet re-conveying unit 4. Enter inside 42. When the recording sheet advances to the passage 43, the switching guide member 37 is rotated clockwise to be switched to a position where the recording sheet is allowed to advance.

A roller 4 is provided in the recording paper re-conveying unit 4.
6 and 47 are provided, and these rollers are driven to rotate in the forward and reverse directions by a drive means which will be described later, and serve to convey the recording paper in the respective directions in both the paths 41 and 42.

The recording sheet conveyed in the second passage 42 passes between the sheet feeding roller 17 and the roller 50 driven by the sheet feeding roller 17 at a predetermined timing, and the sheet reversing section 22 of the image forming unit 1 is driven. Sent to. At this time, the paper feed roller 17 is rotationally driven counterclockwise in the figure.

When the recording sheet passes through the second passage 42,
The image surface is facing upward, and after passing through the paper reversing unit 22, the image surface is facing downward, and the recording paper is sent between the photoconductor 8 and the transfer roller 24 via the registration roller pair 23. . Then, the toner image on the photoconductor 8 is transferred to the back surface of the recording paper (the surface on which the image is not recorded).

For example, in the case where the image of the first page is recorded on the front side of the recording sheet and the image of the second page is recorded on the back side, and these are repeated thereafter for each page, When aligning the recording sheets, the recording sheets are stored in the recording sheet discharge tray 31.
Is discharged to. That is, the positions of the switching guide member 28 and the switching guide member 36 are switched so that the recording paper after fixing is directed toward the paper discharge roller pair 48 provided in the recording paper reversing / conveying unit 5, and the switching guide member 28 is switched. 1 occupies the position shown in FIG. 1 and the switching guide member 36 occupies the position rotated clockwise from the position shown in FIG. 1, and the recording paper ejected by the paper ejection roller pair 48 is accommodated on the tray 31. It is.

The paper feed cassette 3 has the same structure as the paper feed cassette 2 shown in FIG. 2, and even when the recording paper re-conveying unit 4 is loaded and set, the paper feed from this cassette side is performed. Feeding is possible with the simple paper feed tray 6. A through path 49 is provided in the recording paper re-conveying unit 4, and the recording paper sent from the paper feed cassette 3 is sent toward the photoconductor 8 of the image forming unit 1 through the through path 49. .

According to the image forming apparatus of the present invention, with respect to the standard machine shown in FIG. 2, the paper feed cassette 2 is pulled out, and the recording paper re-conveying unit 4 and the recording paper reversing conveying unit 5 are shown in FIG. The image forming apparatus capable of double-sided recording can be completed at a stretch by simply mounting it at each position. That is, an image forming apparatus capable of selectively performing double-sided recording (an image forming apparatus to which a double-sided recording function is added as an option) can be provided.

According to such an image forming apparatus, the recording sheet re-conveying unit 4 and the recording sheet reversing conveying unit 5 are provided.
Since the and are separated systems, the recording paper re-conveying unit 4, which should be called a double-sided unit, has a large-diameter reversing roller 3
It is not necessary to provide 8 and the unit can be made thin. As a result, the image forming apparatus main body can be made compact in the height direction.

Further, since the recording sheet re-conveying unit 4 is not equipped with the reversing roller 38 which becomes heavy, the recording sheet re-conveying unit 4 becomes light in weight and can be easily attached and detached. In particular, when the recording sheet reversing / conveying unit 5 is provided with a drive motor for both the units 4 and 5, the weight of the recording sheet re-conveying unit 4 can be reduced and the detachment / attachment thereof can be further facilitated. Can be done.

In addition to this, the recording paper reversing / conveying unit 5 can be selectively loaded, and a recording paper reversing unit for performing the same function as the recording paper reversing / conveying unit 5 is provided as standard equipment to the standard machine. There is no need to do it.
In particular, the economical burden can be reduced even for a user who does not perform double-sided recording, and if both units are optionally provided on the user side, by mounting these units, double-sided recording can be performed immediately. .

Here, in the image forming apparatus illustrated in FIG. 2, it is assumed that the recording paper discharge side from the image forming unit 1 is the rear end of the image forming unit, which is the rear area of the rear end. The sizes of the image forming unit 1 and the paper feed cassette 2 are determined and arranged so that a predetermined space is formed in the upper region of the rear end of the paper feed cassette 2. That is, the recording paper discharge tray 31
By removing the from the image forming unit 1, a predetermined space is formed in this installation area. By utilizing this space area, the recording sheet reversing / conveying unit 5 can be disposed here as shown in FIG. 1, and thereby the image forming apparatus main body can be made more compact in the height direction. As shown in FIG. 1, the recording sheet reversing / conveying unit 5 can be attached without protruding to the rear end side of the recording sheet reconveying unit 4. On the other hand, with respect to the height of the recording paper reversing / conveying unit 5, it is possible to increase the height of the recording paper reversing / conveying unit 5, and it is also possible to increase the diameter of the reversing roller 38. It is possible to improve the reliability in the reverse conveyance of the sheet.

The recording paper discharge tray 3 shown in FIG.
1 is attached to the image forming unit 1, but it is also attachable to the recording sheet reversing / conveying unit 5 as shown in FIG. If the recording paper discharge tray 31 attached to the unit 1 is made attachable, the recording paper discharge tray 31 will be
5 can also be used in combination, and a tray dedicated to the recording paper reversing / conveying unit is not required, which is advantageous in cost.

Here, if a motor for rotating the sheet conveying system is separately provided for the recording sheet re-conveying unit 4 and the recording sheet reversing conveying unit 5 shown in FIG. The transport unit 4 becomes heavy,
Alternatively, the number of parts increases, which is disadvantageous in terms of cost.

Therefore, such a drive motor is provided only on the side of the recording sheet reversing / conveying unit 5 and the rotational driving force is
By driving both the paper transport systems of both units 4 and 5, the recording paper re-transport unit 4 itself can be lightened,
The number of parts can be reduced.

The recording paper reversing / conveying unit 5 is provided with the drive motor 52 shown in FIGS. 3 and 5, and the gears 53, 5 are rotated by the motor 52 rotating in the forward and reverse directions.
The reversing roller 38 is rotated in the forward and reverse directions via the arrow 4. The recording sheet reversing / conveying unit 5 is further provided with a gear 55 that meshes with the gear 54, a gear 56 that meshes with the gear 54, etc. When the recording sheet re-conveying unit 4 is loaded in the position shown in FIG. Gear 57 is unit 5
Side gear 56 is engaged.

The driving force of the motor 52 is transmitted to the gear 58 and the timing belt 59 via the above-mentioned gear group, and the rollers 46 and 47 (FIG. 1) of the recording sheet reconveying unit 4 are rotationally driven. It should be noted that the rollers 46 and 47 are driven in the forward and reverse directions by the motor 52 rotating in the forward and reverse directions. In FIG. 1, reference numerals 61, 62, 63 and 64 denote sheet guide plates forming the first and second passages 41 and 42, but the illustration thereof is omitted in FIG.

The recording sheet reversing / conveying unit 5 includes a motor 52 which is a drive source for the sheet conveyance including the reversing conveyance of the recording sheet, a gear 56 as a driving member to which the rotational driving force from the motor is transmitted, and the like. I have it,
The recording sheet re-conveying unit 4 is driven for recording sheet conveyance, which engages with the gear 56 of the recording sheet reversing conveying unit 5 loaded in the main body 10 when the recording sheet re-conveying unit 4 is loaded in the image forming apparatus main body 10. It has a gear 57 as a member.

By equipping the recording sheet reversing / conveying unit 5 with the relatively heavy motor 52, the weight of the recording sheet re-conveying unit 4 can be reduced, and this unit can be easily attached and detached. it can. Further, since the recording sheet re-conveying unit 4 does not need to be provided with a drive motor by adopting the above-described configuration, the number of parts can be reduced, which is advantageous in terms of cost.

The recording paper reversing / conveying unit 5 is shown in FIG.
When the sheet is loaded at the position of,
The driving force is transmitted and received from the image forming unit 1 side. As shown in FIGS. 3 and 4, the timing belt 65 is adapted to be rotationally driven by receiving a driving force from a driving source (not shown) of the image forming unit 1.
By the rotation of the timing belt 65, the paper discharge roller 27A and the paper discharge roller 51 shown in FIG. 1 are rotationally driven.

When the recording sheet reversing / conveying unit 5 is loaded in the above-mentioned position, the gear 69 (FIG. 4) provided on the recording sheet reversing / conveying unit 5 is coaxial with the gear 67 meshing with the timing belt 65 and the gear 68. (Provided in the image forming unit 1). When the timing belt 65 is driven in this state, the gears 67, 68, 6
The paper discharge rollers 48A (FIG. 1) on the recording paper reversing / conveying unit 5 side are rotationally driven via 9, 70 and the timing belt 71.

Note that various sensors (not shown) for detecting the recording paper are provided in the respective paper transport paths shown in FIG. 1, and the forward / reverse rotation control of the motor 52 (FIG. 5) or the The position switching control of various switching guide members is performed.

Here, if the paper feed cassette 2 shown in FIG. 2 and the recording paper re-conveying unit 4 shown in FIG. 1 are used as a common case body with respect to the main body portion, it is possible to save mold cost during manufacturing. In addition, the efficiency in manufacturing parts can be improved.

In FIG. 6, the case body 72 is provided with two pins 74, 75 and one positioning pin 76 at the positions shown in the figure, and the notch 77 provided in the carrying unit case 73 is one of the pins. It is fitted in 74.
Although not shown, the notch on the opposite side is also fitted into the pin 75. At the same time, a hole (not shown) provided in the transport unit case 73 (not shown) is fitted into the positioning pin 76. In this way, the case body 72 and the transport unit case 73 are combined to form the recording sheet re-transport unit 4 shown in FIG.

The paper guide plates 63 and 64 provided on the transport unit case 73 are provided at the base end hinge portions 63a,
64a can be rotated upward with respect to the fulcrum, and when they are rotated, both passages 41, 4
2 (Fig. 1) are opened respectively. In addition, the protrusion 73A provided on the transport unit case 73 is an electrical connector portion for relaying signals of various sensors. The unit is also identified at the same time by this portion. or,
The snap 78 provided on the case body 72 is for attaching the transport unit case 73. The case body 72 is provided with a cutout portion 72A, which is a portion into which a hand can be put when the recording sheet re-conveying unit is attached or detached.

FIG. 7 shows the paper feed cassette 2, the main body of which is shown in FIG.
It is composed of the same common case body 72 as shown in FIG.
In the case body 72, the paper receiving member 15 (FIG. 2),
A pair of size guide plates 79 (the other one is not shown), a rear end guide plate 80, a separation pad member 18, a push-up arm 16 (FIG. 2), etc. are attached. By mounting such members, the paper feed cassette 2 shown in FIG. 2 is configured.

If the case body 72 is made of a material that can be integrally molded, the case body can be molded at once with a mold or the like, and in this case, the molds can be unified. This saves mold costs, and also
The efficiency of parts manufacturing is improved, and parts management becomes easier.

In FIG. 1, the reference numeral 9 indicates a sorter, which is installed on the upper portion of the recording sheet reversing / conveying unit 5 via an appropriate mounting adapter (not shown), and a switching guide member. It is equipped with 19. When the sorter 9 is not used, the switching guide member 19 is held at the position shown in the figure, and the recorded recording paper discharged from the paper discharge roller pair 48 is stored on the tray 31. On the other hand, when the sorter 9 is used, the position of the switching guide member 19 is switched so that the discharged sheet enters the sorter 9.

As shown in FIG. 1, if the sorter 9 is accommodated within the unit width of the recording sheet reversing / conveying unit 5, the front-rear direction of the image forming apparatus (left-right direction in FIG. 1).
The width of can be made compact.

The present invention can be widely applied to image forming apparatuses such as analog copying machines.

[0061]

According to the image forming apparatus of the first aspect, the double-sided recording can be performed only by replacing the unit, and the recording sheet re-conveying unit that substantially functions as the double-sided unit. Since it is not necessary to provide a reversing roller or the like, the image forming apparatus main body can be made compact in the height direction, and the unit can be easily attached and detached. Further, the recording paper reversing unit can be selectively loaded, and since it is not necessary to equip this type of recording paper reversing unit as standard equipment, the cost burden on the user who does not perform double-sided recording, etc. Can be reduced.

According to the image forming apparatus of the second aspect,
Since the main body of the image forming apparatus can be made more compact in the height direction and the diameter of the reversing roller can be increased, the reliability in reversing and conveying the recording sheet can be improved.

According to the image forming apparatus of the third aspect,
Since one drive source can drive both the recording sheet re-conveying unit and the recording sheet reversing conveying unit, the number of parts equipped in this type of unit can be reduced, which is advantageous in terms of cost.

According to the image forming apparatus of claim 4,
The recording sheet re-conveying unit and the recording sheet reversing conveying unit can be a common case body for the main body,
It is possible to improve manufacturing efficiency and the like, and it becomes easy to manage parts.

According to the image forming apparatus of the fifth aspect,
Since it is not necessary to equip the recording paper reversing / conveying unit with a dedicated discharge tray, the number of parts can be reduced, which is advantageous in terms of cost.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a normal image forming apparatus that does not have a double-sided recording function.

FIG. 3 is a diagram showing an example of a drive unit of a sheet conveying system such as a recording sheet re-conveying unit and a recording sheet reversing conveying unit.

FIG. 4 is a perspective view showing the structure of the above driving means.

FIG. 5 is a perspective view showing a configuration of driving means such as a sheet conveying system of the recording sheet re-conveying unit and a reversing roller system of the recording sheet reversing conveying unit.

FIG. 6 is an exploded perspective view of a recording sheet reconveying unit.

FIG. 7 is an exploded perspective view of a paper feed cassette.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Paper feed cassette 4 Recording paper re-conveying unit 5 Recording paper reversing / conveying unit 10 Image forming apparatus main body 22 Paper reversing section 31 Recording paper discharging tray 52 Motor as drive source 56 Gear as drive member 57 Driven member gear 72 case body P recording paper P ₀ recording paper as

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area G03G 21/16

Claims (5)

[Claims] 1. An image forming unit having an image recording unit therein, and a paper feed cassette placed at a lower position of the image forming unit, the latter paper feed cassette being relative to the main body of the image forming apparatus. In an image forming apparatus in which an image forming unit is provided with a sheet reversing unit which is detachable and which reverses the recording sheet fed from the sheet feeding cassette, it is detachable from the image forming apparatus main body like the sheet feeding cassette. The recording paper, which is free and has the paper cassette removed and is loaded in the mounting area of the paper cassette, and one side of which has been recorded, is re-conveyed to the image recording unit via the paper reversing unit. It is equipped with a recording paper re-conveying unit, and is detachable from the image forming apparatus main body independently of the recording paper re-conveying unit, and is discharged from the image forming unit and one side is recorded. An image forming apparatus comprising: a recording paper reversing / conveying unit that reverses and conveys a recording sheet that has already been used, and returns the recording sheet during the conveyance and transports it toward a recording paper re-conveying unit. 2. The image forming unit and the paper feed cassette are
When the recording paper discharge side from the image forming unit is the rear end of the image forming unit, a space is formed in the rear end rear region and the upper rear end region of the paper feed cassette. 2. The image forming apparatus according to claim 1, wherein the recording sheet reversing / conveying unit can be arranged in a space area of the recording sheet reversing / conveying unit. 3. The recording sheet reversing / conveying unit has a driving source for conveying the recording sheet and a driving member to which the rotational driving force from the driving source is transmitted. 3. The image forming apparatus according to claim 1, further comprising a driven member for conveying the recording sheet, which is engaged with a driving member of the recording sheet reversing / conveying unit loaded in the main body when the image forming apparatus is loaded. The image forming apparatus according to item 1. 4. The image forming apparatus according to claim 1, wherein the sheet feeding cassette and the recording sheet re-conveying unit have a common case body. 5. The image forming apparatus according to claim 1, wherein the recording paper reversing / conveying unit enables attachment of a recording paper discharge tray attached to the image forming unit.