JPH06179276A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To correct positional shift by simple constitution without providing a motor by providing a feed roller in opposed relation to a drive roller to hold paper along with the drive roller and making the leading end part of a paper prescribing guide tapered. CONSTITUTION:A tapered part 7p is formed to the leading end part of a paper prescribing guide 7e and the paper 13 fed by the tapered part 7p is guided to the main body of the paper prescribing guide 7e to correct the positional shift of the paper 13. Therefore, the paper 13 fed to the gap between a drive roller 7d and a feed roller 7c is corrected in the positional shift of the upper and rear surfaces thereof in a positional shift correction mechanism part 7 to perform center alignment. Subsequently, the paper is again fed to a register roller 9 and the image formed on OPC 2 is again transferred to a transfer charger 3 and fixed by a fixing device 4 to complete the printing opposed to the rear surface of a second stage. The paper is sent out in the direction shown by an arrow C and discharged to a stack part 12 by a discharge roller 11 to complete both-side printing.

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 such as a copying machine or a printer, and more particularly to an image forming apparatus having a double-sided printing mechanism having a function of printing on both sides of paper.

[0002]

2. Description of the Related Art FIGS. 5A and 5B are views showing an example of a conventional image forming apparatus. FIG. 5A is a side view and FIG. 5B is a plan view of a paper width shifting mechanism section.

Among image forming apparatuses such as a copying machine and a printer, a conventional image forming apparatus with a double-sided printing mechanism, which has a function of printing on both sides of a sheet, corrects a misalignment of a sheet center as shown in FIG. Paper width adjusting mechanism 8 for
Is provided to correct the positional deviation of the center between the front surface and the back surface of the paper.

The image forming apparatus shown in FIG. 5 transfers the image formed on the OPC 2 to the paper 13 discharged from the paper feed cassette 1 of the main body 10 and conveyed to the registration rollers 9 by the transfer charger 3. By fixing with the fixing device 4, the printing on the surface in the first stage is completed. Next, the paper 13 that has been printed on the front surface and is conveyed from the direction of arrow A is sent out in the direction of arrow B by the switching lever 5 and conveyed to the DUPLE unit 6, where the front and back are reversed.

The sheet 13 whose front and back sides have been reversed is aligned with the center of the front side and the back side in the sheet width aligning mechanism section 8 and conveyed again to the registration rollers 9 to again transfer the image formed on the OPC 2 to the transfer charger 3. Transcribed by
The fixing on the fixing device 4 completes the second-stage printing on the back surface, and the changeover lever 5 sends it in the direction of arrow C and the discharge roller 11 discharges it to the stack portion 12.

[0006]

In the conventional image forming apparatus as described above, the width adjusting guide 8 of the paper width adjusting mechanism 8 is used.
A motor is required to move a or 8b.
Therefore, the mechanism becomes complicated and space is required,
For this reason, there are drawbacks that the device becomes large and the cost increases. Further, since the operation noise of the motor and the side-by-side guide is generated, there is a problem that noise is large.

[0007]

An image forming apparatus according to the present invention transfers an image formed on an OPC onto a sheet discharged from a sheet feeding cassette of a main body section and conveyed to a registration roller by a transfer charger, After the printing on the front surface of the first stage is completed by fixing in the fixing device, it is conveyed to the DUPLE unit by the switching lever, the front and back are reversed and conveyed to the registration roller, and the image formed on the OPC is again recorded. In the image forming apparatus in which the image is transferred by the transfer charger, fixed by the fixing device, completed the printing on the back surface in the second stage, and conveyed to the discharge roller by the switching lever and discharged to the stack portion, the image is transferred to the DUPLE unit. A misregistration correction mechanism unit for correcting misregistration of a sheet whose front and back sides are reversed is provided. A pair of sheet regulation guides that regulate both sides of the sheet, a driving roller that is provided in front of the sheet regulation guide and conveys the sheet, and a sheet that is provided so as to face the driving roller and holds the sheet. A paper feed roller is provided and the leading end of the paper regulation guide is tapered, or a pair of paper regulation guides that regulate both sides of the paper and a pair of paper regulation guides are provided in front of the paper regulation guide to convey the paper. A drive roller, a transport roller that is provided to face the drive roller and holds the sheet, and a sheet size sensor that detects the width of the sheet that is transported. One of the sheet regulation guides is fixed, and the other sheet regulation guide is made movable according to the width of the sheet detected by the sheet size sensor, or one side of the sheet is regulated. A paper regulation guide, a drive roller provided in front of the paper regulation guide to convey the paper, a conveyance roller provided to face the drive roller for holding the paper, and a conveyance roller for conveying the paper. A sheet position detection sensor for detecting the position and a solenoid coupled to one end of the drive roller for inclining the drive roller with respect to the sheet conveyance direction are provided, and the drive roller is provided for the sheet position detection sensor. The movement is made possible according to the position detected by.

[0008]

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

FIG. 1 is a diagram showing the details of the positional deviation correction mechanism portion of the embodiment shown in FIG. 2, where (a) is a front view and (b) is a plan view.
FIG. 2 is a side view showing the first embodiment of the present invention.

In the embodiment shown in FIG. 2, the image formed on the OPC 2 is transferred by the transfer charger 3 to the paper discharged from the paper feed cassette 1 of the main body 10 and conveyed to the registration roller 9, and the arrow A The printing on the surface of the first stage is completed by transporting in the direction and fixing by the fixing device 4. Next, the paper whose printing on the front surface is completed is sent out in the direction of arrow B by the switching lever 5 and is sent to the DUPLE unit 6
It is then transported to and the front side and the back side are inverted. The sheet whose front and back are reversed is sent to the misregistration correction mechanism section 7.

As shown in FIG. 1, the misregistration correction mechanism section 7 includes a pair of sheet regulation guides 7 that regulate both sides of the sheet 13.
e, a drive roller 7d provided in front of the paper regulation guide 7e to convey the paper 13, a conveyance roller 7c provided opposite to the drive roller 7d for holding the paper 13, and a conveyance roller via a link lever 7b. 7c is moved in the direction of arrow C. A taper portion 7p is formed at the tip of the sheet regulation guide 7e,
The paper 13 conveyed by the tapered portion 7p is guided to the main body of the paper regulation guide 7e to correct the positional deviation.

Therefore, the driving roller 7d and the conveying roller 7c
The sheet 13 conveyed between the sheet and the sheet is corrected in position shift between the front surface and the back surface by the position shift correction mechanism unit 7 and the center is aligned, and then the registration roller 9 is again aligned as shown in FIG. The image formed on the OPC 2 is transferred to the transfer charger 3 and is transferred by the transfer charger 3 and is fixed by the fixing device 4 to complete the printing on the back surface in the second step, and is sent in the direction of arrow C by the switching lever 5. The discharge roller 11 discharges the sheet to the stack section 12 to complete double-sided printing.

3A and 3B are views showing the details of the positional deviation correcting mechanism portion of the second embodiment of the present invention, wherein FIG. 3A is a front view and FIG. 3B is a plan view.

The structure and operation of the driving roller 7d, the conveying roller 7c, the link lever 7b, and the solenoid 7a of the positional deviation correcting mechanism of this embodiment are the same as those of the embodiment of FIG. Below the solenoid 7a, a paper size sensor 7 for detecting the width of the paper 13 being conveyed.
g is provided. The upper paper regulation guide 7fa of the pair of paper regulation guides 7fa and 7fb is fixed, but the lower paper regulation guide 7fb is indicated by an arrow C.
It is movable in the direction, and moves so as to match the width of the sheet 13 detected by the sheet size sensor 7g.

Therefore, the driving roller 7d and the conveying roller 7c
The paper 13 conveyed between the paper and the paper is conveyed between the paper regulation guides 7fa and 7fb having an interval matching the width of the paper 13 detected by the paper size sensor 7g, and the positional deviation between the front surface and the back surface is caused. Is corrected and the center is aligned. The subsequent operation is the same as that of the first embodiment.

4A and 4B are views showing the details of the positional deviation correction mechanism portion of the third embodiment of the present invention, in which FIG. 4A is a front view and FIG. 4B is a plan view.

The construction and operation of the conveying roller 7c, the link lever 7b and the solenoid 7a of the positional deviation correcting mechanism of this embodiment are the same as those of the embodiment of FIG.
A solenoid 7h is coupled to one end of the drive roller 7k, and the movement of the solenoid 7h causes the arrow D to move.
Can move in any direction. In addition, the paper 13 that is conveyed
A paper position detection sensor (not shown) for detecting the position of is provided. Further, the paper regulation guide 7m is only on the upper side, and there is no lower paper regulation guide.

Therefore, the driving roller 7k and the conveying roller 7c
The sheet 13 conveyed between the sheet and the sheet is conveyed toward the sheet regulation guide 7m by the drive roller 7k that changes the position depending on the position of the sheet 13 detected by the sheet position detection sensor, and the misalignment between the front surface and the back surface is corrected. The center is aligned. The subsequent operation is the same as that of the first embodiment.

[0019]

As described above, in the image forming apparatus of the present invention, the DUPLE unit is provided with the misregistration correction mechanism section, and the sheet whose front and back sides are reversed by the DUPLE unit is conveyed to the misregistration correction mechanism section. By compensating the misalignment between the front and back sides and aligning the centers of them by the paper regulation guide of the compensating mechanism, the misalignment can be corrected with a simple structure and without providing a motor. Therefore, there is an effect that the device can be downsized and the cost can be reduced.

[Brief description of drawings]

1A and 1B are diagrams showing details of a positional deviation correction mechanism portion of the embodiment of FIG. 2, where FIG. 1A is a front view and FIG. 1B is a plan view.

FIG. 2 is a side view showing the first embodiment of the present invention.

3A and 3B are diagrams showing details of a positional deviation correction mechanism portion of a second embodiment of the present invention, in which FIG. 3A is a front view and FIG. 3B is a plan view.

4A and 4B are diagrams showing details of a positional deviation correction mechanism portion of a third embodiment of the present invention, in which FIG. 4A is a front view and FIG. 4B is a plan view.

FIG. 5 is a diagram showing an example of a conventional image forming apparatus, (a)
Is a side view and (b) is a plan view of the paper width shifting mechanism section.

[Explanation of symbols]

 1 Paper Cassette 2 OPC 3 Transfer Charger 4 Fixer 5 Switch Lever 6 DUPLE Unit 7 Position Misalignment Mechanism 7a ・ 7h Solenoid 7b Link Lever 7c Transport Roller 7d ・ 7k Drive Roller 7e ・ 7fa ・ 7fb ・ 7m Paper Regulation Guide 7g Paper size sensor 7p Tapered part 8 Paper width shifting mechanism part 9 Registration roller 10 Main body part 11 Discharge roller 12 Stack part 13 Paper

Claims (3)

[Claims] 1. A surface of a first stage by transferring an image formed on an OPC to a sheet discharged from a sheet feeding cassette of a main body section and conveyed to a registration roller by a transfer charger and fixing the image by a fixing device. After the completion of printing on the sheet, it is conveyed to the DUPLE unit by the switching lever, the front and back are reversed and conveyed to the registration roller, and the image formed on the OPC is transferred again by the transfer charger and fixed by the fixing device. In the image forming apparatus that completes the printing on the back surface in the second stage and conveys it to the discharge roller by the switching lever and discharges it to the stack portion, a position to correct the misalignment of the sheet with the front and back reversed in the DUPLE unit. A misregistration correction mechanism unit is provided, and the misregistration correction mechanism unit is provided with a pair of sheet regulation devices that regulate both sides of the sheet. A guide guide, a drive roller provided in front of the paper regulation guide to convey the paper, and a conveyance roller provided to face the drive roller to sandwich the paper, and the tip of the paper regulation guide. An image forming apparatus having a tapered portion. 2. A pair of sheet regulation guides for regulating both sides of the sheet in the misregistration correction mechanism section, a drive roller provided in front of the sheet regulation guide for conveying the sheet, and opposed to the drive roller. And a paper size sensor for detecting the width of the paper being conveyed, and one of the pair of paper regulation guides is fixed. The image forming apparatus according to claim 1, wherein the other sheet regulation guide is movable according to the width of the sheet detected by the sheet size sensor. 3. A misregistration correction mechanism section is provided with a sheet regulation guide for regulating one side of the sheet, a drive roller provided in front of the sheet regulation guide for conveying the sheet, and facing the drive roller. And a conveyance roller that holds the sheet, a sheet position detection sensor that detects the position of the sheet that is conveyed, and a drive roller that is coupled to one end of the drive roller to move the drive roller in the sheet conveyance direction. The image forming apparatus according to claim 1, further comprising a solenoid for inclining the drive roller so that the drive roller can move in accordance with a position detected by the paper position detection sensor.