JP3265261B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper supply path on one side of an image forming apparatus main body, a recording paper conveyance path formed toward a discharge port on the other side, and a recording paper conveying path formed below the apparatus main body. The present invention relates to an image forming apparatus in which an L-shaped reversing unit for double-sided printing is provided independently of the apparatus main body.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent Laid-Open No. 1 (Kokai) No. 1 (1999) -1990, there is known an image forming apparatus in which an image forming apparatus main body is mounted on an L-shaped reversing unit. With this configuration, the lower side of the L-shaped unit is
Since the length dimension can be made longer than that of the apparatus main body, recording paper larger than the recording paper by the cassette built in the apparatus main body can be advantageously stored.

[0003]

However, there is a problem that it takes time to process one sheet of recording paper in order to record images on both sides of the recording paper. In recent years, even when an image is formed on one side, there is a demand for shortening the time for transferring an image to a recording sheet and fixing the image. However, the recording paper conveyance speed in the apparatus main body cannot be increased unnecessarily depending on the image forming speed in the photosensitive drum.

In view of the above circumstances, an object of the present invention is to provide an image forming apparatus in which an L-shaped reversing unit is mounted on an apparatus main body to reduce an image processing time. Another object of the present invention is to provide an image forming apparatus that conveys recording paper at high speed. Another object of the present invention is to provide an image forming apparatus in which accurate feeding control is performed even during high-speed conveyance of recording paper.

[0005]

According to the present invention, an image forming apparatus main body (hereinafter, referred to as an apparatus main body) is provided below the apparatus main body independently of the apparatus main body, and paper is discharged from the apparatus main body. In an image forming apparatus having a reversing unit for receiving a transfer sheet and supplying the inverted transfer sheet to the apparatus main body, the apparatus main body includes a recording paper discharge port on a rear surface and a reception port on a front side bottom surface. Wherein the reversing unit includes a base having a supply port on which the apparatus main body is mounted and supplying a transfer sheet at a position corresponding to the receiving port, and a standing portion rising from the base and from the discharge port to the base. And a paper-passing section having a paper-passing path is formed to have an L-shaped cross section, and a first conveying roller on the paper-passing path of the paper passing section is driven by two-stage control of a low-speed conveyance state and a high-speed conveyance state. 1 drive source, and A second drive source for driving a second transport roller on a transport path for transporting the transfer paper to the front side in a high-speed transport state, and a reversal for reversing the transfer paper transported to the front side and transporting the transfer paper to the reversing storage unit A third drive source for driving the rollers to be rotatable forward and backward in a high-speed transport state, a fourth drive source for driving a discharge roller on a transport path for transporting the inverted transfer sheet to the receiving port in the high-speed transport state, It is characterized by having.

That is, according to the present invention, an image forming apparatus main body (hereinafter referred to as an apparatus main body) is provided with a recording paper discharge port on a rear surface and a receiving port on a front side bottom surface, and the apparatus main body is provided below the apparatus main body. The present invention is applied to an image forming apparatus having a reversing unit, which is provided independently of the printer, receives a transfer sheet discharged from the discharge port, and reverses the received transfer sheet to supply the received transfer sheet to the reception port.

The reversing unit mounted on the apparatus main body includes a base having a supply port for supplying the transfer paper at a position corresponding to the receiving port on which the apparatus main body is mounted, and standing up from the base. And a paper passing portion having a conveyance path from the discharge port to the base provided on a rear surface of the apparatus main body, and is formed in an L-shaped cross section.

Further, a first drive source for driving a first transport roller on a transport path of the paper passing section by two-stage control of a low-speed transport state and a high-speed transport state, and a transfer paper transported from the paper transport section A second drive source for driving a second transport roller on a transport path for transporting the transfer paper to the front side in a high-speed transport state, and a reversing roller for reversing the transfer paper transported to the front side and transporting the transfer paper to the reversing storage unit. The third drive that can be rotated forward and backward in the transport state
A drive source, and a fourth drive source that drives a discharge roller on a transport path that transports the inverted transfer sheet to the reception port in a high-speed transport state.

According to this technical means, even if the image forming process is performed at a predetermined speed in the apparatus main body,
The conveying speed can be changed to a high-speed conveying state in the paper passing section from the recording paper discharge port of the apparatus main body, and the transfer paper is transferred in a high-speed conveying state from the paper passing section to the receiving port on the apparatus main body side. It can be conveyed, and the image processing time can be reduced.

The first drive source switches from a low-speed transport state to a high-speed transport state after the trailing edge of the recording paper has passed through the fixing operation area of the apparatus main body, and the trailing edge of the transfer paper is driven by the trailing edge of the transfer paper. It is also an effective means of the present invention to switch from the high-speed transport state to the low-speed transport state after passing through the paper path.

According to such a technical means, during the fixing operation on the apparatus main body side, the paper is conveyed in the paper passing portion at the same speed as the fixing operation. Even if nipped by the transport rollers in the paper passing section, the transport rollers can be set according to the speed thereof,
Therefore, it is not necessary to provide a distance at which the entire length of the transfer paper can wait until the completion of fixing, on the upstream side of the transport roller, so that the apparatus is downsized.

If the low-speed conveyance state is set to be the same as the conveyance speed for fixing on the apparatus main body side, after the rear end of the transfer paper automatically passes through the fixing operation area of the apparatus main body,
Since the mode is switched from the low-speed transport state to the high-speed transport state, the transfer paper receiving speed is quickly reached, and the image forming processing time is reduced.

In addition, a third transport roller is disposed on the inner side of the reversing storage section with respect to the reversing roller, and the second driving source is connected to a third transportation roller provided on the reversal storage section. The second conveyance roller is driven to be rotatable forward and backward in a high-speed conveyance state, and the rotation direction in which the second conveyance roller conveys the transfer paper to the front surface and the rotation direction in which the third conveyance roller stores the transfer paper in the reversing storage section are set. It is also an effective means of the present invention to form them so as to be identical.

According to this technical means, since the third transport roller is disposed on the back side of the reverse storage section with respect to the reverse roller, that is, on the receiving side of the base for receiving the transfer paper from the paper passing section. The second transport roller and the third transport roller are arranged close to each other, and can be driven by the same second drive source.

Then, the transfer paper is reversed by the reversing roller and is conveyed to the reversing storage section, so that the third conveyance roller rotates in a direction opposite to that of the second conveyance roller, thereby causing the transfer paper to rotate. The transport operation to the reverse storage section is performed, and a rational drive mechanism can be configured by connecting both transport rollers to the one second drive source.

A sensor for detecting the presence or absence of transfer paper is provided on the reversing roller, and the third drive source drives the reversing roller forward when the sensor detects the presence of transfer paper. It is also an effective means of the present invention that the normal rotation drive of the reversing roller is stopped when the sensor detects that there is no transfer paper.

According to this technical means, the reverse roller is provided with a sensor for detecting the presence or absence of transfer paper. That is,
By providing a sensor capable of detecting, for example, the vicinity of the upstream side of the reversing roller (the position where the reversing roller starts to change the transport direction) or the position where the transfer paper is changing the transport direction by the reversing roller. Can be accurately detected and controlled when storage in the inverted storage section is completed.

Further, the third driving source is formed by a stepping motor, and the number of steps is counted at the same time when the reversing roller is reversingly driven, and when the predetermined number is counted, the reversing driving of the reversing roller is stopped. When the sensor detects the leading edge conveyance of the transfer paper, the reverse roller is driven forward and the number of steps is counted at the same time, and when the predetermined number is counted, the reverse drive of the reverse roller is stopped. Means.

As described above, by forming the third driving source by the stepping motor and controlling the driving of the reversing roller by the number of steps, it is possible to accurately control the transfer of the transfer sheet to the reversing storage section. it can.

[0020]

Embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely described. It is only an example.

FIG. 1 is a schematic configuration diagram of a recording paper conveyance control device according to an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is an explanatory diagram illustrating a state in which the image forming apparatus main body, the reversing unit, and the sheet feeding unit are stacked and arranged. In FIG. 3, positioning pins 54, 54 on the reversing portion 26 of the sheet reversing unit (reversing unit) 2 and device holes 52, 5 formed on the lower surface of the image forming apparatus main body (hereinafter, apparatus main body) 1 are shown.
2 and the terminal 57 completes the electrical connection between the apparatus main body 1 and the sheet reversing unit 2.

When a paper cassette (built-in cassette) 6 longer than the length of the apparatus main body 1 in the front-rear direction is set in the apparatus main body 1, as shown in FIG. Since the end protrudes from the rear surface 1b of the apparatus main body 1, the paper passing portion 5 needs to be inclined outward. Also, as shown in FIG.
, A back cover (not shown) is detachably disposed, and the back cover is detached from the apparatus main body 1 when it is combined with the sheet reversing unit 2.

Similarly, the device holes 53, 53 of the sheet reversing unit 2 and the positioning pins 55, 5
5 and the terminal 58 completes the electrical connection between the sheet reversing unit and the sheet feeding unit 3. It should be noted that a plurality of paper feed units having the same size can be mounted in a multi-stage manner, so that a large-capacity image can be recorded.

Further, as shown in FIG.
An electric controller 4 is built in and the terminal 5
The sheet reversing unit 2 and the sheet feeding unit 3 are connected to the controller 4 via 7, 58. A paper cassette (built-in cassette) 6 is provided above the controller 4.
Are arranged, and a multi-purpose tray 8 is provided on the front side of the apparatus main body so that various types of paper can be supplied.

Therefore, an image can be formed on the recording paper even if the paper feeding unit 3 is not disposed. However, a frequently used recording paper such as A4 size is used for the paper feeding unit 3 and the paper feeding is performed. It is preferable that the cassette 6 uses recording paper larger than the recording paper accommodated in the paper feeding unit 3 (for example, A3 size), and that the multi-purpose tray 8 use recording paper smaller than the recording paper used for the paper feeding unit 3. .

A transport unit 10 configured to detachably mount the paper feed cassette 6 is detachably disposed on the apparatus main body 1 (FIG. 5), and a well-known electronic unit is mounted on the apparatus main body 1 and the transport unit 10. Photographic processing means is arranged. A photosensitive drum 9 and a paper feed roller 15 are arranged on the apparatus body 1 side, and are configured to be able to convey the recording paper from the multi-purpose tray 8 to the photosensitive drum 9 side. On the front surface 1a side of the apparatus main body 1 adjacent to the controller 4, a paper path unit 47 for obtaining a driving force from a motor 45 provided in a reversing unit 26 of the sheet reversing unit 2 described later, and a transport roller 48 are provided. Reversing unit 2
The recording paper from the printer can be conveyed to the apparatus main body 1 side. Note that a charger, a cleaning device, a developing device, a latent image forming device, and the like necessary around the photosensitive drum 9 are not shown for convenience.

On the downstream side of the photosensitive drum 9, a fixing roller pair 18, a conveying roller pair 19, and a discharge direction switching guide 2 are provided.
4 (FIG. 2), and the guide 24
Side or the paper passing unit 5 side. The switching of the guide 24 is performed by the operation of the front front panel 25 of the apparatus body 1 or the sheet reversing unit 2.
In the double-sided recording mode, the selection can be automatically switched.

In the single-sided recording mode, the guide 24 forms a path to the paper discharge unit 22 side, and the recording paper
0, the sheet is conveyed to a sheet discharge section 22 via a sheet discharge roller pair 21. In the double-sided recording mode, the guide 24 forms a path to the paper passing unit 5 of the sheet reversing unit 2 described later, and when the image formation on one side of the recording paper is completed, the recording paper is conveyed to the paper passing unit 5. When the recording paper starts image formation on the other side, the guide 24 is switched to form a passage to the paper discharge unit 22 side.

On the transport unit 10 side, the photosensitive drum 9
A registration roller pair 17, a registration sensor 11, a transport roller 16, and a pickup roller 7 are disposed on the upstream side of the transfer roller 12. 1 on the front 1a side,
A multi-purpose tray 8 is arranged so as to be openable and closable (FIG. 2).

Therefore, the transport unit 10 includes the multi-purpose tray 8, the transport rollers 16, and the pair of registration rollers 1.
7. The transfer roller 12 can be integrally pulled out of the apparatus main body 1, and the recording paper jam having the leading end between the photosensitive drum 9 and the fixing roller pair 18 and the recording on the conveyance path on the front side of the jam. It is possible to deal with paper jams.

Next, the configuration of the sheet reversing unit 2 will be described. The paper reversing unit 2 has an L-shaped overall cross-sectional shape, and includes a reversing unit 26 for reversing and feeding recording paper, and a paper passing unit 5.
It is composed of The reversing part 26 is formed in a trapezoidal shape having upper and lower surfaces formed by long sides having a front-rear length longer than the front-rear length of the apparatus main body 1 and short sides having the same length as the lateral width of the apparatus main body 1. Is provided with a reversing mechanism described later.

The paper passing portion 5 is formed as an upright portion on the upper surface of the reversing portion 26 where the apparatus main body 1 is not placed. The left chamber 5a and the right chamber 5b (FIG. 3) are connected to each other by a support (not shown) and integrally formed. The arm 30 to which the left chamber 5a and the right chamber 5b are fixed is rotated with respect to the apparatus main body 1. It is configured so that it can be moved and separated.

As shown in FIG. 2, the paper passing section 5 includes a pair of conveying rollers 29 for receiving the recording sheet from the apparatus main body 1 and conveying the recording sheet to a downstream side, and a discharge tray disposed downstream of the pair of conveying rollers 29. A discharge roller pair 28 that discharges the recording paper to 31, a conveyance roller pair 34 that is disposed downstream of the conveyance roller pair 29 and conveys the recording paper to the reversing unit 26 side, and is disposed at a discharge port to the reversing unit 26. A sensor 36 disposed between the transport roller pair 29 and the paper discharge roller pair 28 and the paper discharge tray 31
Switching guide 3 for switching the transport of recording paper to and from the 6th side
2, a solenoid 33 for driving the guide 32, a space in which the rear end of the sheet feeding cassette 6 is inserted, a motor 35 disposed on the left chamber 5a side of the space, and the like.

The recording paper in the paper passing section 5 is driven by a driving force transmitted from a motor 35 via a belt 61.
The belt 61 includes a rotating shaft 35 a of the motor 35 and the roller 5.
0, one roller 29A of the pair of transport rollers, one roller 28A of the pair of discharge rollers 28, and one roller 34A of the pair of transport rollers 34. And
The roller 50 is disposed so as to be slightly adjustable left and right in order to adjust the tension of the belt.

The space into which the leading end of the sheet cassette 6 is inserted is provided at substantially the center of the sheet passing section 5 except for the rollers, and the motor 35 is also provided in the area where the sheet cassette 6 extends. It is arranged at a position shifted laterally. A flat motor is used as the motor 35, and the lengths of the conveying roller pairs 29 and 34 and the belt 61 are set to be substantially the same from the motor rotation shaft 35a. It is desirable to set. Note that the motor 35 and each roller may be connected by a gear. Further, the connecting portion between the discharge roller 28A and the belt 61 is separate from the connecting portion between the discharging roller 28A and the belt 61, and the connecting portion between the discharging roller 28A and the belt 61 is frictionally connected.
It is desirable that the difference in feed speed between the above and the above can be adjusted by the friction.

As described above, the controller 4 is disposed at the lowermost portion of the apparatus main body 1, the paper feed cassette 6 of the transport unit 10 is located thereon, and the fixing roller is disposed on the upper surface side of the transport unit 10 from the recording paper transport start end. Since the transport path to the pair 18 is formed, the vertical distance from the transport path to the lower surface of the apparatus main body 1, that is, the height can be increased. This means that the reversing portion 26 facing the bottom surface of the apparatus main body 1 from the receiving port on the paper passing section 5 side for receiving the recording paper transferred from the recording paper discharge port on the apparatus main body side communicating with the conveyance path. Therefore, the distance to the upper surface of the motor 5 can be increased, so that the paper transport path in the paper passing unit 5 can be formed in a large arc shape around the rotation axis of the motor 5, and unreasonable bending can be prevented. A sufficient transport space can be secured.

The reversing section 26 is provided along the transport path with the transport rollers 3.
7A, 37B, a sensor 38, a pair of transport rollers 39A, 39B to which a driving force is transmitted from a motor 49, a sensor 40, and a transport roller 4 to which a driving force is transmitted from a step motor 44.
1A, 41B, sensor 42, drive roller 39A of transport roller pair 39 and drive roller 37A of transport roller pair 37
A tension roller 43 for adjusting the degree of tension of the belt 62 stretched around, and a pair of transport rollers 46A and 46B to which a driving force is transmitted from a motor 45 are provided. still,
The motor 45 is configured to be able to transmit a driving force to the transport roller 48 of the paper path unit 47 via a gear train (not shown).

The recording paper transported by the transport roller pairs 37, 39, 41 passes through the sensor 42 at the leading end and is transported deeper than the transport roller pair 43. It stops in the state of being pinched by the pair 41. At this time, the rotation of the motor 49 that drives the transport roller pairs 37 and 39 and the tension roller 43 also stops.

When the recording paper is fed reversely, the recording paper is rotated by the reverse rotation of the forward / reverse rotating motor 44 with the conveyance roller pair 41 sandwiching the recording paper.
The reverse feed of 1 is reversed. Then, the sheet is conveyed to the apparatus main body 1 by the motor 45 via the conveying roller pair 46. Here, the sensors 38, 40, and 42 detect the leading and trailing ends of the recording paper and control the forward and reverse rotation of the motor 44. That is, while the recording paper is being detected by the sensor 38, the motor 44 continues to rotate forward, and continues to rotate forward when the sensor 40 is on and the sensor 42 is on, but when the sensor 40 is off. Stop rotation.

Next, the operation of performing double-sided printing using the sheet reversing unit 2 will be described in more detail. In the present embodiment, the motor and the sensor are arranged and controlled at predetermined positions in the unit so as to reduce the waiting time when performing double-sided printing, and the speed of the transport motor 35 is controlled by the paper transport position. The switching between the forward and reverse rotations of the transport motor 49 and the forward and reverse rotation of the reverse motor 44 are performed.

The condition that the registration roller pair 17 in the apparatus main body 1 conveys the recording paper to the transfer roller 12 side is determined by the sensor 1
Third, the sensor 36 and the sensor 38 do not detect the recording paper. Then, the operation of the transport motor 35 arranged in the paper passing section 5 is started in response to the operation of the registration sensor 11 arranged in front of the registration roller pair 17 of the apparatus main body 1. Then, gradually increase the rotation speed.
Slow-up control for shifting to low-speed rotation (linear speed of 163 mm / sec) is performed over 5 seconds. As a result, it is possible to prevent skew in the sheet reversing unit 2, that is, non-uniformity of the sheet feeding function due to twisting or bending at the time of starting the transport member.

Therefore, when the apparatus main body 1 starts printing, the sheet reversing unit 2 enters an operable standby state. When the trailing edge of the recording paper on which the image has been transferred to one side is detected by the sensor 13 disposed downstream of the pair of fixing rollers 18, the transport motor 35 rotates at a timing at which the trailing edge comes off the pair of transport rollers 19. (Linear speed 282 mm / sec)
When it is detected that the trailing edge of the recording paper has reached the sensor 36, the rotation is switched to the low-speed rotation in a standby state, and the recording paper corresponding to the next recording paper is transmitted.

When the trailing edge of the next recording paper is detected by the sensor 13, the rotation is switched from low-speed rotation to high-speed rotation. As described above, the transport motor 35 is switched from the low speed to the high speed in synchronization with the end of fixing of the recording paper, and is controlled so as to immediately transport the recording paper to the reversing unit 26.

On the other hand, after the sensor 42 in the reversing unit 26 detects the transferred recording paper in the transport path 70, the sensor 42 in the transport path 70 waits until the leading end of the recording paper is detected by the sensor 11. The end is configured to escape the detection area of the sensor 42.

The rotation speed of the motor 49 reaches a high speed by the time the sensor 36 detects the leading edge of the recording paper in the paper passing unit 5. When the transfer paper reaches the transport roller pair 37, the rotation speed is high. Done.

Therefore, the leading end of the recording paper that has passed the sensor 36 enters the conveying path 69 at a high speed, and the conveying roller pair 3
When the sensor 38 detects between 7 and 39 and the leading edge of the recording paper is detected by the sensor 38, the motor 44 starts high-speed forward rotation. Further, after the leading edge of the recording paper is detected by the sensor 40, the sensor is detected by the sensor 42, and the trailing edge is detected by the sensor 4.
The motor 49 and the motor 4
4 stops. At that time, the transport rollers 41A and 41A
B stops with the recording paper sandwiched.

The motor 49 and the motor 49 are driven on the condition that the preceding recording paper is conveyed by the registration roller 17 and the recording paper is not conveyed from the conveyance path 71, and that the leading end of the recording paper is not detected by the sensor 36. Motor 4
4 is reversed and re-fed to the apparatus main body 1. At this time, the number of steps of the motor 44 is counted at the same time as the reverse rotation of the motor 44, and the motor 49 is rotated in the reverse direction until the rear end of the re-fed recording paper is out of the drive range of the transport rollers 41A and 41B. Stop. Note that the motor 49 may be stopped at a timing when the rear end of the recording paper is out of the driving range of the tension roller 43. In this state, the motor 49 can rotate forward to enter a state of receiving the recording paper in the paper passing unit 5. Therefore, it is desirable that the tension roller 43 is located at the left end of the transport path 70 as much as possible.

Further, even if the motor 49 is conveying the recording paper and the trailing end of the recording paper loses the detection of the sensor 36, the conveyance path 7
When the recording paper at 0 does not fall out of the holding area of the transport roller pair 41, the motor 49 stops and the recording paper is made to wait in the transport path 69. When the sensor 42 detects the trailing edge of the recording sheet and rotates until the recording sheet moves out of the holding area of the conveying roller pair 41, the motors 49 and 44 rotate forward and a new rotation The recording paper will be conveyed. A discharge roller 46 connected to a discharge motor 45
Performs registration at the time of re-feeding into the apparatus main body 1 using the nip of the roller.

[0049]

As described above, according to the present invention, the conveying speed can be changed to the high-speed conveying state in the paper passing portion, and the transfer from the paper passing portion to the receiving port on the apparatus body side can be performed. The paper can be transported in a high-speed transport state, and the image processing time can be reduced. In addition, after the rear end of the transfer paper automatically passes through the fixing operation area of the apparatus main body, the mode is switched from the low-speed transport state to the high-speed transport state.
The transfer paper receiving speed is quickly reached, and the image forming processing time is shortened.

Further, the first drive source in the paper passing unit switches from a low-speed transport state to a high-speed transport state after the trailing end of the recording paper has passed the fixing operation area of the apparatus main body, and After the rear end passes through the paper path of the paper passing section,
Since the apparatus is configured to switch from the high-speed transport state to the low-speed transport state, it is not necessary to provide a distance that allows the entire length of the transfer paper to wait for the completion of fixing upstream of the transport roller. I do.

The reversing roller is provided with a sensor for detecting the presence or absence of transfer paper. When the sensor detects the presence of transfer paper, the reversing roller is driven to rotate forward, and the sensor detects the absence of transfer paper. In such a case, the normal rotation drive of the reversing roller is stopped, so that the transfer of the transfer sheet to the reversing storage unit can be accurately controlled. It has a remarkable effect.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an explanatory diagram illustrating a state in which an image forming apparatus main body, a sheet reversing unit, and a sheet feeding unit are stacked and arranged.

FIG. 4 is a perspective view showing a rear end portion of the apparatus main body.

FIG. 5 is a perspective view showing a transport unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Paper reversing unit 5 Paper passing part (standing part) 26 Reversing part (base) 29, 34 Transport roller (first transport roller) 35 Motor (first drive source) 37, 39 Transport roller ( (Second transport roller) 41 reversing roller 44 motor (third drive source) 45 motor (fourth drive source) 46 discharge roller

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masahiro Murakami 3-9, Tamatsuzo Motomachi, Tennoji-ku, Osaka-shi, Osaka Mita Techno Design Co., Ltd. Examiner Manji Mizutani (56) References JP-A-9-194097 (JP) JP-A-8-15931 (JP, A) JP-A-62-290668 (JP, A) JP-A-63-45745 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B65H 29/58

Claims (6)

(57) [Claims] 1. An image forming apparatus main body (hereinafter, apparatus main body)
And provided below the apparatus main body independently of the apparatus main body and receives the transfer paper discharged from the apparatus main body,
And an image forming apparatus having a reversing unit for reversing the received transfer paper and supplying it to the apparatus main body, wherein the apparatus main body is provided with a recording paper discharge port on a rear surface and a receiving port on a front side bottom surface, The reversing unit includes a base having a supply port on which the apparatus main body is mounted and supplying a transfer sheet at a position corresponding to the receiving port, and a transport path rising from the base and extending from the discharge port to the base. A first drive source for forming a L-shaped cross section by providing a paper passing unit, and driving a first transport roller on a transport path of the paper transport unit by two-stage control of a low-speed transport state and a high-speed transport state; A second drive source for driving a second conveyance roller on a conveyance path for conveying the transfer paper conveyed from the paper passing section to the front side in a high-speed conveyance state; and inverting the transfer paper conveyed to the front side. High-speed transport of the reversing roller transported to the reversing storage section A third driving source for driving the paper to be rotatable forward and backward in a feeding state; and a fourth driving source for driving, in a high-speed conveyance state, a discharge roller on a conveyance path for conveying the inverted transfer sheet to the receiving port. An image forming apparatus comprising: 2. The first drive source switches from a low-speed conveyance state to a high-speed conveyance state after a rear end of the recording paper passes through a fixing operation area of the apparatus main body. 2. The image forming apparatus according to claim 1, wherein the high-speed conveyance state is switched to the low-speed conveyance state after passing through a paper path. 3. A third conveyance roller is disposed on the back side of the reversing storage section with respect to the reversing roller, and the second driving source is connected to a third conveyance roller provided on the reversing storage section. The second conveying roller is driven to rotate forward and backward in a high-speed conveying state, and the rotational direction in which the second conveying roller conveys the transfer paper to the front surface and the rotational direction in which the third conveying roller stores in the reversing storage section are The image forming apparatus according to claim 1, wherein the image forming apparatuses are formed to be the same. 4. A sensor for detecting the presence or absence of transfer paper is provided on the reversing roller, wherein the third drive source drives the reversing roller forward when the sensor detects the presence of transfer paper, 2. The image forming apparatus according to claim 1, wherein when the sensor detects that there is no transfer paper, the normal rotation driving of the reversing roller is stopped. 5. The method according to claim 1, wherein the third driving source is formed by a stepping motor, and the number of steps is counted at the same time when the reversing roller is driven to be reversed. The image forming apparatus according to claim 1. 6. A sensor for detecting that the leading edge of the transfer sheet has been conveyed to the reversing roller, wherein the third drive source is formed by a stepping motor, and the sensor detects that the leading edge of the transfer sheet has been conveyed. 2. The image forming apparatus according to claim 1, wherein the number of steps is counted at the same time when the reverse roller is driven forward, and when the predetermined number is counted, the forward drive of the reverse roller is stopped.