JP2003128319A - Paper inverting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper inverting device hardly causing a jam. SOLUTION: Paper 15 is secondarily transferred by an intermediate transfer drum 8 and a transfer roller 9, and is fixed by a fixing device 5. Then paper 15 is conveyed from a conveyance roller 22 to an inversion unit 30b via conveyance rollers 41, 42, 43, 44, 45 and 46. In the inversion paper feeding unit 30b, the paper 15 is almost horizontally conveyed and then U-turnedly inverted, conveyed by conveyance rollers 45 and 46 which rotate reversely. The paper 15 is conveyed further to the intermediate transfer drum 8 and the transfer roller 9 via a conveyance roller 47, a relay roller 36, a conveyance roller 37 and register roller 12. The paper 15 is secondarily transferred on the back side surface by the intermediate transfer drum 8 and the transfer roller 9. A controller 7 stops the paper temporarily on the conveyance path in the inversion unit 30b where the conveyance rollers 42, 43 and 44 are disposed almost in the horizontal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet reversing device, and more particularly to a sheet reversing device that reverses a sheet after passing a substantially horizontal conveying path and a U-turn path.

[0002]

2. Description of the Related Art As a conventional paper reversing device on which a printer main body can be placed, for example, as shown in Japanese Patent No. 3178599, a single-sided printed paper is received and a horizontal direction is provided below the printer main body. In some cases, after being conveyed to the printer body, it is inverted in a U shape and conveyed again to the printer body.

[0003]

However, in the conventional paper reversing device, if the printer body is capable of color printing, one side of which is color-printed is accepted, but the color-printed paper has an increased curl amount. In addition, due to the demand for space saving and downsizing of the paper reversing device itself, the conveyance route is set to a short and abrupt path route, which causes a problem that jam easily occurs in the paper reversing device. there were.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it accepts a sheet printed on one side, reverses it after passing through a substantially horizontal transport path and a U-turn path, and In the sheet reversing device that conveys the sheet again to the image forming unit, the sheet reversing device includes a control unit that temporarily stops the sheet on the substantially horizontal conveying path.

Alternatively, the sheet reversal is such that the sheet having one side printed thereon is received, and the sheet is inverted after passing through a substantially horizontal conveyance path capable of keeping most of the conveyed sheet in a substantially horizontal state and then conveyed again to the image forming section. In the apparatus, the paper reversing device is provided with a control means for temporarily stopping the paper on any substantially horizontal transport path formed in the paper reversing device.

The sheet reversing device of the present invention may be one in which an image forming device such as a printer is mounted, or one mounted in the image forming device.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a color image forming apparatus equipped with a sheet reversing device of the present invention. The photosensitive drum 1 and four developing devices 4 for each color
a to 4d, a reflection type photo sensor 6 for reading a reference position mark formed on the outer peripheral surface of the photoconductor drum 1 for generating a reference position signal in the sub-scanning direction of the photoconductor drum 1, an intermediate transfer body drum 8, A next transfer roller 9, a separation charger 10, and a pair of registration rollers 12 are provided.

In such a color image forming apparatus,
The photosensitive surface of the photosensitive drum 1 is charged by a charging device (not shown), and the charged photosensitive surface of the photosensitive drum 1 is charged by a laser light unit (not shown) on the basis of the surface charge based on image information. It is exposed to form an electrostatic latent image.

The electrostatic latent image on the photosensitive drum 1 is, for example, magenta (red), yellow (yellow), cyan (blue) color toner, and black (black) toner by four developing devices 4a to 4d. Are sequentially developed using. At this time, the photo sensor 6 generates a reference position signal of the photosensitive drum 1 in the sub-scanning direction, and based on this signal, the toner images of the respective colors are developed so as not to shift from each other.

At each development, the toner image is primary-transferred in order onto the surface of the intermediate transfer drum 8 which is rotated in contact with the photosensitive drum 1, and finally four colors are transferred onto the intermediate transfer drum 8. Color toner images are transferred in multiple.

The paper 15 that is sandwiched between the secondary transfer roller 9 and the intermediate transfer drum 8 on which the color toner images have been multi-transferred from the photosensitive drum 1 to the surface is fed by the secondary transfer roller 9. By charging the paper 15, the multiple color toner images on the intermediate transfer drum 8 are secondarily transferred.

The transfer paper 15 to which the color toner image has been secondarily transferred passes through between the secondary transfer roller 9 and the intermediate transfer drum 8, and is then charged by the separating charger 10 at the time of the secondary transfer. Erased and intermediate transfer drum 8
And is fed to the left in the figure by the transport belt 3 and is fixed by the fixing device 5 as a full-color image.

By the way, as shown in FIG. 2, the photo sensor 6 and the fourth paper sensor 57 are adapted to input a signal to the controller 7 which is the control means, and the controller 7 is also provided with the secondary transfer roller 9 and , Registration roller 1
2, a signal is output to the paper transport means such as the transport belt 3, the transport rollers 22, 23 and 24, and the discharge rollers 25 and 26.

The above-mentioned structure is provided in the main body unit 20 which constitutes the image forming apparatus, and the auxiliary unit 30 is laminated below the main body unit 20.
A sheet feeding unit 30a is provided below the accessory unit 30, and a reversing unit 30b is provided above the accessory unit 30.
Is provided.

In the main unit 20, the manual tray 1
The paper 15 from the paper 7 is passed through the feed roller 19 and the registration roller 12, and the color toner image is secondarily transferred by the intermediate transfer body drum 8 and the secondary transfer roller 9, and then the conveyor belt 3, the fixing device 5, and the conveyor roller. 22, 23, 24,
The tray 28 is discharged through the discharge roller 25 in the direction of arrow A so as to be face down, and the tray 28 is moved from the transport roller 22 through the discharge roller 26 in the direction of arrow B to be face up. Discharged on top.

In the main unit 20 and the accessory unit 30, the paper 15 from the paper feeding unit 30a is sent to the registration roller 12 via the pickup roller 32, the carrying rollers 34 and 35, the relay roller 36, and the carrying roller 37.

The sheet 15 from the carrying roller 22 after being secondarily transferred by the intermediate transfer drum 8 and the secondary transfer roller 9 and further fixed by the fixing device 5 is discharged in the A or B direction. Besides, the reversing unit 30
b, and the transport rollers 41, 42, 43, 4
4, 45, and 46, the sheet is sent to the reversing sheet feeding unit 30b and is conveyed in a substantially horizontal direction to be inverted in a U shape and turned upside down. Then, the secondary transfer can be performed on the rear surface of the paper 15 by the intermediate transfer drum 8 and the secondary transfer roller 9 via the transport roller 37, the registration roller 12, and the transfer roller 37. Each of the rollers and the conveyor belt 3 described above constitutes a paper conveyor.

Several paper sensors are arranged in the middle of the paper transport path. That is, the first paper sensor 51 before the conveyance roller 35, the second paper sensor 53 before the relay roller 36, the third paper sensor 55 before the conveyance roller 37, the fourth paper sensor 57 before the registration roller 12, The fifth sheet sensor 59 before the transport roller 24, the sixth sheet sensor 61 behind the discharge roller 25, the seventh sheet sensor 63 before the discharge roller 26, the transport roller 22 of the main unit 20, and the transport of the reversing unit 30b. Eighth and ninth paper sensors 65 and 67 between the rollers 41, a tenth paper sensor 69 between the transport rollers 43 and 44, and an eleventh sensor 70 behind the transport rollers 46.
Is provided.

Such paper sensors 51, 53, 55,
57, 59, 61, 63, 65, 67, 69, 70 are
Current transport position of paper 15 and paper jam (paper jam)
The jam position of the paper 15 at that time can be detected.

Further, a multi-color toner image is formed on the intermediate transfer drum 8 without the toner images of the respective colors being displaced by the reference position detection signal of the photosensitive drum 1 in the sub-scanning direction input to the controller 7 by the photo sensor 6. As soon as it is determined that the registration roller 12 is formed, the registration roller 12
The paper 15 which has been waiting at the secondary transfer roller 9 is conveyed.
Thus, the color toner image is secondarily transferred onto the transfer paper 15.

In such a structure, the present invention is characterized in that the controller 7 temporarily stops the paper on the substantially horizontal transport path of the transport rollers 42, 43, 44. By removing the heat of the paper 15 by this stop, it is possible to suppress the deformation of the paper 15 due to the curl of the front and back sides before performing the U-shaped reversal, and it is possible to reduce the frequency of paper jam occurrence. Further, when the one-sided printing is only one color, the controller 7 may perform control so that the curl amount is small and the U-shape is inverted as it is without being stopped once.

As a further example, by using the conveying roller 47 as a curl correcting means for correcting the curl of the paper 15, it becomes possible to further suppress the deformation due to the curl. As a specific example of the operation as the curl forcing means, as shown in FIG. 3, the upper roller 47c with which the rear surface of the conveying roller 47 to be printed is in contact is a rigid roller made of a rigid material such as metal, and the surface is in contact with the upper roller 47c. The lower roller 47b may be an elastic roller formed of an elastic body such as rubber on the cored bar 47a. By such a conveying roller 47, the paper 15 curled on the one-sided printing side by the one-sided printing process can be more surely corrected in the opposite direction. The lower roller 47b of the transport roller 47
By making the diameter of the core bar 47a larger than the diameter of the upper roller 47c, it is possible to suppress the bending even when a high load is applied from the upper roller 47c. In this embodiment, the transport roller 47 is the decurling correction means, but the relay roller 36 may be the curl correction means or a new correction means may be provided.

Further, in order not to reduce the double-sided printing processing speed as much as possible, the controller 7 detects the trailing edge of the sheet by the eighth sheet sensor 65 or the ninth sheet sensor 67, or the ninth sheet sensor 67 or the tenth sheet. When the sensor 69 detects the leading edge of the sheet and detects that the sheet 15 is conveyed to the reversing unit 30b, the reversing unit 30b is detected.
Each of the conveying rollers 41, 42, 43, 44, 45, 46 may be rotated at a high speed and switched to a low speed (normal printing speed) in order to surely perform the curl correction when the decurling correction means is reached. Switching from the high speed to the low speed is performed when the decurling correction unit is the transport roller 47.
It may be carried out after or 5 and 46 are reversed, or a predetermined time after the reversal, or a predetermined time after the leading edge of the paper is detected by the 11th paper sensor 70. In the present embodiment, the case of switching from the high speed to the normal printing speed has been described, but it is possible to switch to the low speed equal to or lower than the normal printing speed only when passing through the decurling correction means and return to the normal printing speed after passing through the Kyo curling correction means. Good. In any case, the decal correction can be performed more reliably by setting the speed to be low when passing through the decal correction means. Further, as a further embodiment, only the paper having the paper thickness may be switched at a low speed.

The above description is for the first invention of the present invention.
The case where the paper is temporarily stopped on the conveyance path in the substantially horizontal direction of the portions 2, 43 and 44 has been described. This is because it is most preferable that the sheet 15 is temporarily stopped before the U-shaped reversal to remove the heat from the sheet, but the sheet 15 is temporarily stopped in the reversing unit 30b on any one of the substantially horizontal conveyance paths. If the control is performed so that the frequency of occurrence of paper jam can be reduced, which is the object of the present invention. For example, in the case of the reversing unit 30b of FIG. 1, it may be controlled so as not to be immediately sent out but to be temporarily stopped in the substantially horizontal conveyance path portion constituted by the conveyance rollers 45 and 46 after U-shaped reversal. .

Further, the reversing unit 30 as shown in FIG.
In the case of b, the conveyance path C, which is a substantially horizontal conveyance path portion
It is before the U-shaped inversion that the control is performed so as to stop once, which corresponds to the first invention of the present invention. In addition, you may control to stop once in the conveyance path D which becomes a conveyance part of a substantially horizontal direction similarly. Further, the conveyance roller E may be a curl correcting means as shown in FIG. 3, or the above-mentioned high speed / low speed control may be performed.

[0026]

As described above, according to the sheet reversing apparatus of the present invention, the sheet reversing apparatus is provided with the control means for temporarily stopping the sheet on the substantially horizontal conveyance path before passing the U-turn path, or in the substantially horizontal direction. By providing the control means for temporarily stopping the paper on the conveyance path, it is possible to provide the paper reversing device in which the jam hardly occurs in the device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a color image forming apparatus equipped with a sheet reversing device of the present invention.

FIG. 2 is a block diagram showing a main part of a color image forming apparatus equipped with a sheet reversing device of the present invention.

FIG. 3 is a diagram showing decurling correction means in the sheet reversing device of the present invention.

FIG. 4 is a diagram showing another embodiment of the sheet reversing device of the present invention.

[Explanation of symbols]

1: Photoconductor drum 3: Conveyor belts 4a to 4d: Developing device 5: Fixing device 6: Photosensor 7: Controller 8: Intermediate transfer drum 9: Secondary transfer roller 10: Separation charger 12: Registration roller 15: Paper 17 : Manual tray 19: Feed roller 20: Main unit 30: Attached unit 30a: Paper feeding unit 30b: Inversion unit 22, 23, 24, 34, 35, 37, 41, 42, 4
3, 44, 45, 46, 47: Conveying rollers 25, 26: Ejecting roller 27: Tray unit 28: Tray 32: Pickup roller 36: Relay roller 51: First sheet sensor 53: Second sheet sensor 55: Third sheet Sensor 57: 4th paper sensor 59: 5th paper sensor 61: 6th paper sensor 63: 7th paper sensor 65: 8th paper sensor 67: 9th paper sensor 69: 10th paper sensor 70: 11th paper sensor

Claims (4)

[Claims] 1. A sheet reversing device that receives a sheet printed on one side, reverses the sheet after passing through a substantially horizontal conveying path and a U-turn path, and then conveys the sheet again to an image forming unit.
A sheet reversing device comprising a control unit for temporarily stopping the sheet on the substantially horizontal conveyance path. 2. A curl straightening device for straightening a curl of a sheet is provided on a conveyance path after the sheet is reversed.
The sheet reversing device described. 3. The paper reversing device according to claim 2, wherein the control means reduces the transport speed when the paper reaches the curl correcting means. 4. A sheet reversing device that receives a sheet printed on one side, passes through a substantially horizontal conveying path that allows most of the conveyed sheet to be in a substantially horizontal state, reverses the sheet, and conveys the sheet again to the image forming unit. A paper reversing device, characterized in that the device is provided with a control means for temporarily stopping the paper on any of the substantially horizontal conveying paths formed in the paper reversing device.