JP2001097622A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper reversing unit of an image forming device which can switch first and second passages in a simple structure, and can save the space at a low cost. SOLUTION: In the paper reversing unit of image forming device, a guide plate 15 is movably disposed at the junction area 10d of the first passage 10a and the second passage 10b, with one side end fixed to the second passage 10b, and with the other side end allowing the paper coming from the direction of the arrow (a) to pass through the first passage 10a, and preventing the paper going to the inlet of the second passage 10b from entering the first passage 10a.

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 provided with a sheet reversing unit.

[0002]

2. Description of the Related Art A conventional image forming apparatus is provided with a sheet reversing unit used for double-sided printing. Regarding the configuration of such a sheet reversing unit, as shown in FIG. 4, a sheet that has been processed on one side and conveyed from the image forming apparatus main body is guided into the reversing unit main body 100 as indicated by an arrow 100x. Body 10
0 passes through the first path 101 formed in the inside. The passed paper is detected by the sensor 106 which detects the leading end, and the rear end of the paper is detected. The paper 106 passes through the switchback roller 102 and is conveyed to the stock unit 103 in a state where the rear end of the paper is clamped and stopped. Then, the switchback roller 102 rotates in the reverse direction with the rear end of the stopped
Is conveyed toward a second path 104 branched from the path 101, and is conveyed in the direction of arrow b by the switching guide 107 to be sent from the sheet reversing unit main body 100 to the image forming apparatus main body.

In the operation of the sheet reversing unit 100 having such a configuration, a sheet 106 coming from a direction of an arrow 100x is detected by a sensor 106 in a branch area 105 of a first path 101 and a second path 102, and a switching guide 107 is provided. Is the first
The solenoid 108 operates so as to open the path 101. On the other hand, when the sheet is conveyed from the stock unit 103 to the second path 104, the switching guide 107 is switched in the dotted line direction, and is configured to be guided in the direction of the arrow 100y.

[0004]

However, in the reversing unit having such a configuration, the switching guide 107 is required.
Also, a solenoid 108 for operating the solenoid 108 is required. In order to operate the solenoid 108, a power source as a power source thereof and a control circuit for transmitting the operation timing of the solenoid are separately required. And the space and cost for installing the solenoid 108 are increased.

Further, since the first path 101 and the second path 105 are switched at the timing by the sensor 106, the switching guide 107 does not operate properly due to a malfunction of the sensor 106, causing a jam or the like. Had.

The present invention has been made in view of the above-described problems, and has a simple configuration and a first and second paths 101 and 104.
It is another object of the present invention to provide a sheet reversing unit of an image forming apparatus which can be switched at a low cost, saves space and saves jams and the like.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention introduces a sheet on which an image is formed on one side into a sheet reversing section and forms a first sheet formed in the sheet reversing section.
And stopping the sheet by passing through the path, the image forming apparatus configured to guide the sheet to an entrance of a second path branched from the first path and to send out the sheet from the sheet reversing unit. In a branch area of the first path and the second path, one end is fixed to the second path, and the other end can pass through the first path immediately after the sheet is guided into the sheet reversing unit, Further, a guide plate is provided which moves so that a sheet heading for the entrance of the second path does not enter the first path.

According to the structure of the present invention, the one-sided processed sheet passing through the first conveying path is conveyed while passing under the other end of the guide plate, and after the sheet has passed through the guide plate, the second sheet. The guide plate prevents the paper heading to the entrance of the first path from entering the first path, so that the sheet can easily enter the second path and change the transport direction. Thereby, it is possible to switch the conveyance of the paper from the first path to the second path by using only the guide plate without using a special switching guide. As a result, the structure is simplified, and the complicated work at the time of manufacturing is reduced. Can be eliminated. Further, since the first path and the second path are not switched by using the paper detection sensor, a jam due to a malfunction of the sensor does not occur.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 illustrates a printer as a specific example of the image forming apparatus of the present invention. A printer indicated by X as a whole is mounted on a paper feed unit Z that stores sheets in a stacked state and on an upper surface of the paper feed unit Z,
And an apparatus main body Y having a sheet reversing section Y ′.

At the center of the apparatus main body Y, an image forming section P having various process means around the photosensitive member 1 is positioned. More specifically, on the peripheral surface of the photoconductor 1, light is emitted in accordance with image information, starting from a charging unit 2 that is disposed above the photoconductor 1 and uniformly charges the surface of the photoconductor 1. Exposure means 3 for irradiating the photoreceptor 1 with the laser light, developing means 4 for developing an electrostatic latent image formed by the exposure means 3, and transfer means for transferring the toner image visualized by the development means 4 onto paper. 5. Cleaning means 6 for removing the residual toner remaining on the photoreceptor surface without being transferred is arranged in this order in the clockwise direction of the photoreceptor 1, and particularly, the transfer means 6 is provided below the photoreceptor 1 It is positioned.

Below the image forming section P, a manual sheet feeding section Z 'provided on the right side in the drawing passes through a transfer area formed between the transfer means 5 and the photosensitive member 1 and passes through the image forming section P. There is provided a paper transport path 8 for supplying paper to the fixing means 9 provided at the lower left portion of the printer and transporting the paper to the downstream side of the fixing means 9. Then, the paper supplied from the manual paper feed unit Z ′ is
After being temporarily stopped by the pair of registration rollers 80 positioned below the developing unit 4 on the transport path 8, the toner image formed by the image forming unit P is transferred by the transfer unit 6 to a correct position on the sheet surface. The timing is controlled to re-drive the pair of registration rollers 80, the toner image is transferred to the surface thereof, and then thermally fused by the fixing unit 9, thereby completing the toner printing on the paper. The paper on which the toner printing has been completed is discharged to the upper discharge part Q or the side discharge part R through the discharge paths 83 and 84 selected by the discharge path switching means 82 provided on the downstream side of the fixing means 9. .

On the other hand, a paper feed cassette 7 is provided in a paper feed unit Z located below the apparatus main body Y. From the paper feed cassette 7, paper is fed through a cassette paper feed path 72 described below. Through the transfer area. That is, the sheets stacked on the sheet stacking section 70 of the sheet cassette 7 are fed from the uppermost sheet by the sheet feeding roller 71, and the unit Z
After passing through a delivery opening 73 provided on the upper surface of the apparatus main body Y, it enters a cassette paper feed path 72 of the apparatus main body Y through a receiving opening 74 provided on the lower surface of the apparatus main body Y so as to correspond to the delivery opening 73. I do. The cassette paper feed path 72 joins the paper feed path 8 that feeds the paper from the manual feed section Z ′ to the fixing unit 9 at the paper feed path merging area A upstream of the registration roller pair 80, and It is guided to the transfer area and the fixing means 9.

The apparatus main body Y of the printer X is provided with a conveying means for double-sided printing inside thereof, and passes through the fixing means 9 a sheet on which a toner image is printed on one side, and a pair of registration rollers 80 as necessary. Up to retransmission. Specifically, a conveyance path switching unit 85 is provided downstream of the fixing unit 9 on the sheet conveyance path 8, and the discharge path 8 is provided.
The conveyance path is switched to guide the sheet to the sheet 3, 84, or to guide the sheet to the reversing conveyance path 10 of the sheet reversing unit Y 'for resending.

The sheet passing through the reversing conveyance path 10 by the conveyance path switching means 85 is supplied to the sheet exit 1 of the sheet reversing section Y '.
Area A where the transport path discharged from the paper feed path 4, the transport path from the manual paper feed section Z ′, and the paper transport path 72 from the paper cassette 7 are joined.
The paper, which has been printed on one side, changes its transport direction by 180 degrees when passing through the merge area A, and is guided to the registration roller pair 80. At this time, the upper surface of the paper is the printing surface in the paper transport path 8, but at the position of the registration roller pair 80, the lower surface is temporarily stopped with the lower surface as the printing surface. As a result, when the sheet is re-fed to the transfer area by the registration roller pair, the toner image can be transferred to the non-printing surface of the sheet.

The paper on which the toner images have been printed on both sides in this way passes through the fixing means 9 and is guided to the discharge path by the transport path switching means 85 and 82, and the paper is discharged.

Next, the specific structure of the sheet reversing unit Y 'will be described with reference to FIG. Reversing conveyance path 1 of sheet reversing section Y '
0 is the first transport path 10a, the stock section 10b and the second
And a transfer path 10c. First transport path 10
a, a receiving port 11 for receiving a sheet coming from the fixing device 9 is formed, and a receiving roller 12 is disposed in the vicinity of the receiving port 11. Is formed in a U-shape so that the sheet is turned upside down. The stock unit 10b is provided horizontally on the installation surface of the image forming apparatus X, conveys the single-sided processed paper conveyed from the first conveyance path 10a and stops at a predetermined position, and Is provided with a switchback roller pair 13 configured to perform reverse rotation. The second transport path 10c is located at a branch area 10d from the first transport path 10a.
It is formed so as to be inverted into a letter shape and communicate with the sheet outlet 14 of the sheet reversing section Y ′.

As shown in FIG. 2, a branch area 10d of the first and second transport paths 10a and 10c of the reverse transport path 10 includes:
A guide plate 15 fixed to one transport surface 16 of the second transport path 10c is provided. As the material of the guide plate 15, a sheet-like elastic member made of a material such as PET, polyester, or polycarbonate is used, and a material that can press the lower surface of the first conveyance path 10a with a predetermined pressure is selected.

One end 151 of the guide plate 15 is directly fixed using an adhesive means such as an adhesive.
52 is a free end. The free end of the guide plate 15 abuts on the lower transport surface of the first transport path 10a, presses the first transport path 10a, and is always closed. Therefore, the arrow a
The paper coming from the direction passes through the free end side of the guide plate 15 and is conveyed to the switchback roller pair 13 side.

On the other hand, the guide plate 15 is always in the second conveying path 1.
The paper which has opened the entrance of Oc and has passed through the guide plate 15 is configured so as not to enter the first transport path 10a when transported in reverse by the switchback roller pair 13. Therefore, the switchback roller pair 1
3 comes to the second conveyance path 1 in the branch area 10d.
It naturally enters 0c.

The guide plate 15 is connected to the first transport path 10a.
A concave portion 10e is formed at a position where it comes into contact with the first conveying path 10a.
The free end of No. 5 enters the lower side by a distance s. Thus, when the paper is switched back from the stock unit 10b, the leading end of the paper can be prevented from being caught on the free end of the guide plate 15.

In such a configuration, the angle θ between the guide plate 15 and the first transport path 10a is 30 degrees or less, preferably about 20 degrees, so that the paper coming from the direction of arrow a can pass through the guide plate 15. Is preferred. The reason for this depends on the elasticity determined by the material of the guide plate 15 and the like. However, if the angle θ is 30 degrees or more, the pressing force increases, and it tends to be difficult to pass through the paper. If the angle is smaller than 20 degrees, there is a possibility that the sheet sent from the switchback roller pair 13 enters the first conveyance path 10a.

As another embodiment of the guide plate 5, as shown in FIG. 3, it is preferable to form protrusions 51 to 55 at the tip of the guide 5. Thereby, the stiffness of the passing paper can be reduced, and the jam can be prevented. The first transport path 10 formed adjacent to each of the convex portions 51 to 55 is formed.
a transport guides 10f, 10g, 10h, 10i, 10
Depending on the type of paper, j and 10k are formed such that the widthwise side edge of the paper passes through the upper surface thereof.

Next, the operation of the present invention will be described. FIG.
As shown in (1), the single-sided processed paper transported from the apparatus main body Y by the transport path switching means 85 enters through the receiving port 11 and is transported inside by the receiving roller 12. Thereafter, the sheet is placed under the guide plate 15 shown in FIG.
Through the switchback roller pair 13 and the stock unit 1
0b. At this time, while the trailing edge of the sheet is detected by a sensor (not shown), the sheet is stopped while holding the trailing edge of the sheet. Then, the switchback roller pair 13 is prevented from rotating in the reverse direction and coming into contact with the guide 15 to be fed into the first transport path 10a, and enters the entrance of the second transport path.
Further, the sheet that has been discharged from the sheet outlet 14 of the sheet reversing unit Y ′ and has been turned over to the registration roller 80 of the image forming unit Y and has been subjected to the one-sided processing is again supplied. Thereafter, an image is formed in the image forming section Y and is discharged.

[0024]

According to the constitution of the present invention, the guide plate is provided in the branch area of the second conveyance path in which the single-sided processed sheet after fixing is reversed in the first path and resupplied to the image forming section. While forming this guide plate, one end is fixed to the second path, the other end is closed so that single-sided processed paper introduced from the image forming unit can pass through the first path, and Because the entrance to the second route is arranged to be open,
Thereby, the one-side-processed sheet is reversed while passing under the guide plate that has closed the first transport path, and after the reversal, the paper always enters the opened second path, so that the transport direction can be easily changed, As a result, it is possible to use the guide plate of the present invention only from the first path to the second path without using a special switching guide.
Can be switched to the conveyance of the paper. Therefore, the structure can be simplified, and complicated operations during manufacturing can be eliminated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an outline of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating a structure of a branch area in a reverse conveyance path according to the present invention.

FIG. 3 is a view illustrating another embodiment of the guide plate of the present invention.

FIG. 4 is a diagram illustrating a structure of a sheet reversing unit of a conventional image forming apparatus.

[Explanation of symbols]

 X: Printer Y: Image forming unit Y ': Paper reversing unit Z: Automatic paper feeding unit 1: Photoreceptor 2: Charger 3: Exposure unit 4: Developing unit 5: Transfer unit 6: Cleaning unit 7: Sheet cassette 71 : Paper feed roller 8: transport path 9: fixing device 10: reverse transport path 10 a: first transport path 10 b: stock section 10 c: second transport path 10 d: branch area

Claims (2)

[Claims] 1. A sheet on which an image is formed on one side is guided into a sheet reversing section, and a first sheet formed in the sheet reversing section is introduced into the sheet reversing section.
And stopping the sheet by passing through the path, and guiding the sheet to an entrance of a second path branched from the first path and sending out the sheet from the sheet reversing unit. One end of the first path and the branch area of the second path
2 is fixed to the path, the other end can pass through the first path paper immediately after being guided into the paper reversing section, and,
An image forming apparatus comprising: a guide plate that moves so that a sheet heading for an entrance of the second path does not enter the first path. 2. The image forming apparatus according to claim 1, wherein said guide plate is made of an elastic member, and said first passage is closed by being elastically pressed by said guide plate.