JPH10139247A - Two-sides images forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing costs and shrink the proprietarily occupying space by forming a recording sheet switch-back passage structure, furnished in an inversive transport part of a two-sideds images forming device, from a small number of component parts and in a simple configuration. SOLUTION: This two-sideds images forming device is structured so that each recording sheet of paper P on whose one surface an image has been formed, is switched back by an inversive transport device 40, upset up and down, and fed by a re-feeding part 70 to an image formation part 10, where an image is formed also on the other surface. An inverting space for recording sheet furnished in the inversive transport part 40 is located between over the guide surface of a body skeleton bottom plate 100 of this image forming device and under the guide surface of the body 21 of a sheet feed cassette.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided image forming apparatus for conveying a sheet of recording paper and forming images on both sides of the recording paper.

[0002]

2. Description of the Related Art Conventionally, in a double-sided image forming apparatus of this type, recording paper fed from a paper supply unit from a recording paper storage container such as a paper supply cassette of a recording paper storage unit is guided to an image forming unit. The recording paper on which one-sided image has been formed is switched back and upside down in the reversing conveyance section, the recording paper is fed from the recording paper introduction section into the double-sided image forming storage container (intermediate stacker), and the recording paper is fed again. The sheet is sent to the image forming unit by a paper unit to form an image on both sides of the recording sheet, and then discharged outside the apparatus.

[0003]

The above two-sided image forming apparatus has the following problems.

(1) In the reversing conveyance section, the recording paper on which single-side recording has been performed is normally conveyed, accommodated in a temporary reversal space, temporarily stopped, and then the recording paper is conveyed in a reverse direction. Conventionally, the reversal space for temporarily storing the recording paper is formed by a passage structure including a dedicated guide member formed of sheet metal, resin, or the like below the intermediate stacker. For this reason, since a dedicated guide member is required, the number of parts and the number of assembling steps increase, and the manufacturing cost increases. In addition, if a dedicated guide member attaching / detaching or opening / closing mechanism is provided, the apparatus becomes complicated. Further, since a space for disposing the dedicated guide member is required, the size of the apparatus is increased.

(2) When the recording paper on which an image has been formed on one side is forwardly conveyed by a reversible reversing roller provided in the reversing conveyance section and temporarily stored in the reversing conveyance section. In some cases, a reverse end of the recording paper may not be able to pass through the nip position of the conveyance roller due to a defective setting of a recording paper size, a timing error of a timer, or the like. When the recording paper is excessively fed, if the detecting means for detecting the recording paper is installed on the upstream side of the reversing roller in the normal rotation direction, the jam detection due to the excessive feeding of the recording paper is performed. Can't be sure.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and (1) reduces the manufacturing cost without forming a recording paper reversing conveyance path in a reversing conveyance section with a dedicated guide member. And (2) to provide a double-sided image forming apparatus that reliably detects a jam when recording paper is excessively fed at a nip position of a reverse conveyance roller. .

According to a first aspect of the present invention, there is provided a double-sided image forming apparatus in which a recording sheet on which an image has been formed on one side is switched back in a reversing conveyance section to be turned upside down, and the recording sheet is fed again. In a double-sided image forming apparatus that forms an image on both sides of a recording sheet by sending it to an image forming unit by a paper unit, a reversal space that accommodates recording paper provided in the reversing conveyance unit is formed by a bottom frame of a main body frame of the double-sided image forming apparatus. It is characterized by being provided on the upper part.

According to a second aspect of the present invention, there is provided a double-sided image forming apparatus according to the present invention, wherein an upper surface of the main body skeleton bottom plate is used as a guide surface.

According to a third aspect of the present invention, there is provided a double-sided image forming apparatus according to the present invention, wherein the reversal space is provided below a recording paper storage unit.

According to a fourth aspect of the present invention, there is provided a double-sided image forming apparatus according to the present invention, wherein a lower surface of a bottom plate of the recording paper storage portion is a guide surface.

According to another aspect of the present invention, there is provided a double-sided image forming apparatus in which a recording sheet having an image formed on one side is switched back in a reversing conveyance section to turn over the recording sheet. In a double-sided image forming apparatus in which an image is formed on both sides of a recording sheet by being sent to an image forming unit by a re-feeding unit, a downstream side in a recording sheet normal conveying direction of a reversible conveying roller provided in the reversing conveying unit and capable of normal and reverse rotation. And a detecting means for detecting the recording paper.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a double-sided image forming apparatus according to the present invention will be described below. FIG. 1 is a schematic configuration diagram of a double-sided image forming apparatus, and FIG. 2 is a schematic diagram illustrating a recording paper conveyance path of the double-sided image forming apparatus.

In this embodiment, a copying apparatus is shown as a double-sided image forming apparatus. The copying apparatus includes an image forming unit 10, a paper feeding unit 20, a paper discharging unit 30, a reverse conveying unit 40,
, Recording paper introduction unit 50, intermediate stacker unit (storage unit) 6
0, and a paper re-feeding unit 70 for feeding the recording paper P to the transfer unit of the image forming unit 10 and discharging or re-feeding the recorded recording paper P from the transfer unit. A conveyance path B, a discharge path C for discharging the recording paper P on which the image is formed to the outside of the apparatus, and a circulation path for recirculating the recording paper P on which the image is formed in the image forming section 10 to the image forming section 10 after reversing And a circulation reversing paper feed path D.

An image carrier (photosensitive drum) 11 is disposed in the image forming section 10. The image carrier 11 is uniformly charged by a charger 12, and image information is carried by an exposure unit 13. Irradiate the peripheral surface of the body 11 to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 14 to form a toner image.

The paper feed unit 20 (storage unit) has at least one
One paper feed unit is provided. The paper feed unit includes a paper feed cassette main body 21 for storing a large number of recording papers P.
(Storage container) is arranged to be able to be pulled out. Reference numeral 22 denotes a movable bottom plate that presses the recording paper P against the paper feed roller 23. By driving and rotating the paper feed roller 23, the uppermost recording paper P on the movable bottom plate 22 is intermittently taken out.
On the downstream side of the paper feed roller 23, a double feed prevention roller pair 24, 25 is arranged to send out the recording paper P one by one to the next process. The paper is fed to a second paper feed roller (registration roller) 28 via 26 and 27. The “storage section” of the recording paper in the present invention refers to the intermediate stacker section 60 or the paper feeding section 2.
Means 0.

The second paper feed roller 25 is driven in synchronization with the rotation of the image carrier 11, and the recording paper P is sent to the transfer unit 15 to transfer the toner image. After that, the recording paper P is separated from the image carrier 11 by the separator 16, and is conveyed to the fixing device 18 by the conveyance belt 17. Further, around the image carrier 11,
A cleaning device 19 is provided, and the image carrier 1 after transfer is provided.
1 to remove residual toner on the surface. Further, for the next image formation, the charger 12 charges again.

The recording paper P heated and pressed by the fixing device 18
The toner image is fixed thereon. The fixed recording paper P is sent to the paper discharge unit 30. That is, the recording paper P passes through the nip position of the paper discharge guide roller 31 disposed on the downstream side of the conveyance of the fixing device 18, and is further conveyed by the paper discharge switching member (switching gate) 32 on the downstream side of the conveyance. Is switched between the discharge side and the reversing and re-feeding side. The recording sheet P switched to the discharge side passes through a path above the switching gate 32 and is placed on a discharge tray 34 by a discharge roller 33.

On the reversing and re-feeding side of the recording paper, a reversing conveyance section 40 is provided.
, A recording paper introduction unit 50, an intermediate stacker unit 60, and a paper re-feeding unit 70.

FIG. 3 shows the reverse transport section 40 and the recording paper introduction section 5.
0 is a sectional view.

When the switching gate 32 is switched to the reverse re-feeding side, the recording paper P that has passed through the path a below the switching gate 32 is transported downward via the transport roller 41 of the reverse transport section 40 and branches. The member 42 passes through the left side passage b in the drawing of the member 42, and further passes through the vertical passage c on the downstream side of the conveyance, and is conveyed while being nipped by the reversible conveyance roller 43 that can rotate forward and reverse.
The course is bent in the horizontal direction by the curved passage d, and a switchback passage (horizontal passage) formed in a reversal space E provided above the main body skeleton bottom plate 100 of the image forming apparatus main body and below the recording paper storage unit. e, and is temporarily stopped at a predetermined position and accommodated. The leading end position of the sheet at the time of the stop differs depending on the size of the sheet, but the trailing end position of the recording sheet P of each size is an intermediate position between the nip position of the branch member 42 and the conveying roller 43.

The trailing end of the temporarily stopped recording paper P is
Nipped by the reverse conveyance roller 43 switched to the reverse rotation drive, the vertical path c is raised, and the branch member 42
Then, the recording paper is fed into the intermediate stacker 60 by the recording paper introduction unit 50 (discharge passage g).

The reversal space is preferably a space formed by the upper surface of the main body frame bottom plate 100 and the lower surface of the recording paper storage portion (in this embodiment, the lower surface of the storage container bottom plate). Reference numeral 44 denotes a pressing lever which guides the leading end of the large-size recording paper by light pressure contact, and is preferably provided to prevent the recording paper from being stored in a curled state. Further, it is preferable that a guide member is not newly provided, and the upper surface of the main body skeleton bottom plate or the lower surface of the bottom plate of the recording paper storage unit (the lower surface of the storage container bottom plate in this embodiment) is used as the guide surface.

The upper surface 10 of the main body frame bottom plate 100
A rib or the like is formed on the lower surface of the recording paper storage section (or the lower surface of the storage container bottom plate in the present embodiment) to serve as a guide surface to further facilitate switchback conveyance of the recording paper P, Alternatively, the recording paper storage section (the storage container bottom plate in the present embodiment) may be reinforced. Further, as a modification of the present embodiment, when the intermediate stacker unit and the paper feed are switched upside down, the bottom plate of the recording paper storage unit becomes the bottom plate of the intermediate stacker unit.

A detecting means for detecting the recording paper is provided downstream of the reversing conveyance roller 43 in the recording paper normal conveyance direction, and detects the leading edge, the trailing edge, and the presence or absence of the recording paper. The detecting means includes a detecting member 45 and an optical sensor 46. The detecting member 45 includes an actuator part 45A and the light shielding part 4.
5B and a shaft 45C. The support shaft 45C is rotatably supported by a fixed bearing (not shown) of the reversing conveyance section 40.

The actuator section 45A is connected to a recording paper P passing through a vertical path c on the downstream side of the reverse conveying roller 43.
It is rocked in contact with. The light shielding part 45B integrated with the actuator part 45A blocks or transmits the detection optical path of the optical sensor 46. The optical sensor 46 is a photo interrupter type optical sensor.

FIG. 4 is a block diagram of a control unit for controlling the conveyance of the recording sheet by the reverse conveyance unit 40.

(1) A sheet size signal is sent from the image forming apparatus main body to the control unit 80, and a timer clock corresponding to the sheet size is set.

(2) The passage a below the switching gate 32
Is transported downward through the forwardly rotating transport roller 41 of the reverse transport section 40, and the branching member 42
, And further conveyed through a vertical passage c on the downstream side of the conveyance while being nipped by the reverse conveyance roller 43.

(3) The leading end of the recording paper P is
5, when passing through the actuator section 45A, the actuator section 45A is swung so that the light shielding section 45B
Is swung, and the detection optical path of the optical sensor 46 is blocked (OF).
F) is switched to the transmission state (ON).

(4) When the detection optical path is turned on, the optical sensor 46 sends a signal to start the passage of the recording paper to the control unit 80, and starts the timer timing corresponding to the paper size.

(5) After the predetermined timer measurement is completed, when the paper is normally conveyed, the trailing end of the recording paper P is
Forward conveyance is temporarily stopped in a state where the sheet is nipped. The actuator unit 45A of the detection member 45 retreats from the vertical path c from the passage of the recording paper P to the temporary stop, and the optical sensor 46 maintains the ON state.

(6) Next, when a recording paper reversal conveyance start signal is input to the control unit 80, the reversal conveyance roller 43 is reversed by the reverse driving of the motor M3, and the recording paper P is nipped by the reversal conveyance roller 43. And are transported in reverse.

(7) At the time of the forward rotation transport, the recording paper P is excessively fed due to a timer timing defect or the like, so that the rear end portion of the recording paper passes through the nip position of the reverse transport roller 43 and the detection member 45 When the actuator section 45A passes the detection position of the actuator section 45A, the actuator section 45A is swung, the detection optical path of the optical sensor 46 is cut off and turned off, and the control section 80 issues a display or an alarm indicating the occurrence of a jam. At the same time, the driving of the device is stopped.

If the detection means for detecting the passage of the leading edge of the recording paper P is provided on the upstream side of the reverse transport roller 43 at the time of normal rotation transport, if the recording paper P is excessively fed. Even when the trailing end of the recording sheet P is nipped by the reversing conveyance roller 43, the detecting unit detects the passage of the trailing end of the recording sheet, and the control unit 80 generates a display or an alarm indicating that a jam has occurred. .

A transport belt 52 wound between a driving roller 51A and a driven roller 51B and a backup plate 53 are provided at a fixed position on an upper portion of the upstream side of the intermediate stacker section 60. The driving roller 51A is provided with a motor M1.
To rotate the transport belt 523.

A wire winding drum 54A is installed at a fixed position on the bottom of the stacker main body 61, and is driven and rotated by a motor M2. A movable wire 55 is wound a plurality of times on the drum surface of the wire winding drum 54A, and one end is locked. The other end of the movable wire 55 is stretchably stretched between the intermediate roller 54B and the locking member 54C.

A driven roller 56 A rotatable at a fixed position and a movable wire 5
5 and a driven roller 56B that can rotate while moving. The driven rollers 56A and 56B are
And is driven to rotate.

The locking member 54C and the driven roller 5
6B and a carriage supporting a spring means for urging the driven roller 56B toward the conveying belt, the stacker main body 61
Can be moved linearly by sliding in an elongated hole 610 formed in a side wall parallel to the recording paper conveying direction. The movement of the carriage is driven by the motor M2 via drive transmission means.

The recording paper P discharged into the stacker main body 61 from the pressure contact position between the transport belt 52 and the driven roller 56B
After passing through the space of the discharge passage g and contacting the bottom surface in the stacker main body 61 or the upper surface of the preceding recording paper P stacked in the stacker main body 61, slides and abuts. It is transferred to the surface 61A.

[0040]

As described above, in the double-sided image forming apparatus according to the first aspect, the reversal space of the recording paper provided in the reversing conveyance section is provided above the main body frame bottom plate of the double-sided image forming apparatus. There is an advantage that the device can be downsized without requiring a dedicated inversion space.

The double-sided image forming apparatus according to the third aspect has an advantage that the apparatus can be downsized because a dedicated inversion space is not required.

A double-sided image forming apparatus according to claim 2 or 4, wherein the upper surface of the bottom plate of the main frame is used as a guide surface.
Alternatively, since the lower surface of the recording paper storage section (in this embodiment, the lower surface of the storage container bottom plate) is used as a guide surface, a passage structure including a dedicated guide member is not required. There is no need to provide an opening and closing mechanism,
This is effective in reducing manufacturing costs by reducing the number of parts and assembly steps. Furthermore, there is an advantage that a space for disposing a dedicated guide member is not required and the apparatus can be downsized.

In the double-sided image forming apparatus according to the fifth aspect, a detecting means for detecting the recording paper is provided on the downstream side in the recording paper normal transporting direction of the reversible transport roller provided in the reversing transport section. Thereby, the detection of the passage of the leading end of the recording paper and the display indicating the occurrence of the jam or the generation of the alarm become accurate.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a double-sided image forming apparatus.

FIG. 2 is a schematic diagram illustrating a recording paper transport path of the double-sided image forming apparatus.

FIG. 3 is a cross-sectional view of a reverse conveyance unit and a recording paper introduction unit.

FIG. 4 is a block diagram of a control unit that controls recording paper conveyance of a reverse conveyance unit.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 image forming unit 20 paper feed unit (storage unit) 21 paper feed cassette main body 21A bottom surface (guide surface) 30 paper discharge unit 40 reverse transport unit 43 reverse transport roller 44 pressing lever 45 detection member 46 optical sensor 50 recording paper introduction unit 60 Intermediate stacker section (storage section) 61 Stacker body 70 Refeed section 80 Control section 100 Main body frame bottom plate 100A Top surface (guide surface) P Recording paper (paper) e Recording paper switchback path (horizontal path, temporary storage for recording paper)

Claims (5)

[Claims] 1. A recording sheet on which an image has been formed on one side is switched back in a reversing conveyance section to turn over, and the recording sheet is sent out to an image forming section by a re-feeding section to form images on both sides of the recording sheet. In the double-sided image forming apparatus, a reversal space for accommodating recording paper provided in the reversal conveyance unit is
A double-sided image forming apparatus, wherein the double-sided image forming apparatus is provided above a bottom plate of a main body frame of the double-sided image forming apparatus. 2. The double-sided image forming apparatus according to claim 1, wherein an upper surface of the main body skeleton bottom plate is used as a guide surface. 3. The double-sided image forming apparatus according to claim 1, wherein the reversing space is provided at a lower portion of a recording paper storage portion. 4. The double-sided image forming apparatus according to claim 3, wherein a lower surface of a bottom plate of the recording paper storage portion is used as a guide surface. 5. A recording sheet on which an image has been formed on one side is switched back in a reversing conveyance section to turn over, and the recording sheet is sent out to an image forming section by a re-feeding section to form images on both sides of the recording sheet. In the double-sided image forming apparatus, a detecting unit for detecting a recording sheet is provided on a downstream side in a recording sheet normal conveying direction of a reversible conveying roller provided in the reversing conveying unit and capable of normal and reverse rotation. apparatus.