JPH08143183A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device which is constituted to generate image outputs, the centers of which coincide with each other, when a paper sheet is skewed. CONSTITUTION: An image forming device comprises a conveyance roller pair 16 to convey paper sheets P fed from a feed paper cassette 11 along the direction of a conveyance reference center K; and a resist roller pair 18 to feed the paper sheet P to a gap between a transfer charger 6 and a photo-sensitive substance drum 2 after the tip position thereof is regulated along a direction crossing a conveyance direction at right angles is provided. Further, after the tip position of the paper sheet P is regulated by a resist roller pair 18, a positioning means is provided to position the center of the paper sheet to a conveyance reference center K by pressing the side of the paper sheet P while the resist roller pair 18 is reversed after the tip position of the paper sheet P is regulated by the resist roller pair 18.

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 applied as an electrophotographic apparatus, for example.

[0002]

2. Description of the Related Art In an electrophotographic apparatus, an image is formed on a photosensitive drum by image forming means and the image is transferred onto a sheet by an image transfer section. The above-mentioned paper is fed from the paper feed cassette, and the fed paper is sent to the aligning roller via the carrying roller. The sheet is aligned by aligning the skew of the leading end of the sheet with the aligning roller, and then sent to the image transfer section.

By the way, when the paper is tilted at the time of aligning the paper or feeding and conveying the paper, the center of the paper may deviate from the center in the conveyance standard direction.

[0004]

However, in the prior art, during the aligning operation of the paper, only the inclination of the leading edge of the conveyed paper was corrected, and the deviation of the paper center was not corrected. Therefore, the photosensitive drum is not corrected. The image transferred from the paper is transferred in a state of being offset from the center of the paper, and it is not possible to obtain an image output with the center aligned.

Therefore, it is an object of the present invention to provide an image forming apparatus capable of correcting the inclination of the leading edge of a sheet and also positioning the center of the sheet at a conveyance standard center to obtain an image output in which the center is aligned. And

[0006]

In order to solve the above-mentioned problems, the present invention provides an image carrier for carrying an image, and an image carried by the image carrier, which is transferred to a sheet. Transfer means, paper feeding means for feeding the paper to be supplied between the transfer means and the image carrier, and conveying means for conveying the paper fed by the paper feeding means along a conveyance reference center. Then, by bringing the leading end of the sheet conveyed by the conveying unit into contact with the sheet, the leading end is aligned along the direction orthogonal to the conveying direction, and then the sheet is transferred between the transfer unit and the image carrier. And a positioning means for positioning the center of the paper at the transport standard center after the leading edge of the paper is aligned by the alignment means.

According to a second aspect of the present invention, an image carrier for carrying an image, a transfer means for transferring the image carried by the image carrier onto a sheet, and a space between the transfer means and the image carrier. A sheet feeding unit that feeds the sheet to be fed, a conveying unit that conveys the sheet fed by the sheet feeding unit along a conveyance reference center, and a leading end of the sheet conveyed by the conveying unit in a stopped state. By bringing them into contact with each other, the leading end of the sheet is aligned along a direction orthogonal to the transport direction, and then it is rotated in the reverse direction. And a positioning unit for pressing the sheet in the direction orthogonal to the transport direction of the sheet to position its center at the transport standard center while the aligning unit is rotating in the reverse direction. Become.

According to a third aspect of the present invention, an image carrier for carrying an image, a transfer means for transferring the image carried by the image carrier onto a sheet, and a space between the transfer means and the image carrier. A sheet feeding unit that feeds the sheet to be fed, a conveying unit that conveys the sheet fed by the sheet feeding unit along a conveyance reference center, and a leading end of the sheet conveyed by the conveying unit in a stopped state. By bringing them into contact with each other, the leading end of the sheet is aligned along a direction orthogonal to the transport direction, and then it is rotated in the reverse direction. Alignment means for feeding between and positioning means for positioning the center of the sheet at the conveyance standard center by pressing the sheet in a direction orthogonal to the conveyance direction according to the size of the sheet while the alignment means is rotating in the reverse direction. And.

According to a fourth aspect of the present invention, an image carrier for carrying an image, a transfer means for transferring the image carried by the image carrier onto a sheet, and a space between the transfer means and the image carrier. A sheet feeding unit that feeds the sheet to be fed, a conveying unit that conveys the sheet fed by the sheet feeding unit along a conveyance reference center, and a leading end of the sheet conveyed by the conveying unit in a stopped state. By bringing them into contact with each other, the leading end of the sheet is aligned along a direction orthogonal to the transport direction, and then it is rotated in the reverse direction. Alignment means for feeding between, positioning means for pressing the sheet in the direction orthogonal to the transport direction of the sheet to position its center at the transport standard center while the aligning means is rotating in the reverse direction, and the transport means. The paper conveyed by the front When the sheet reaches the aligning unit, the detecting unit detects the sheet, and when the detecting unit detects the sheet and a predetermined time elapses, and the leading end of the sheet is aligned, the sheet is conveyed by the conveying unit. And a control means for stopping the transportation and restarting the transportation of the paper by the transportation means when the aligning means is rotated in the forward direction.

According to a fifth aspect of the present invention, an image carrier for carrying an image, a transfer means for transferring the image carried on the image carrier to a sheet, a carrying roller for carrying the sheet, and a carrying roller. Is provided between the transfer means and the transfer means, and after aligning the leading end of the sheet conveyed by the conveying roller,
A registration roller that conveys the sheet to the transfer unit by rotating in the first direction, and a detection unit that is provided upstream of the registration roller in the sheet conveyance direction and detects when the sheet reaches the registration roller. And is provided upstream of the registration roller in the paper conveyance direction,
When the detection unit detects that the sheet has reached the registration roller, the sheet is moved in a direction orthogonal to the sheet conveyance direction to correct and position the sheet in the direction orthogonal to the conveyance direction. Positioning means and the detection means stop the conveyance operation by the conveyance means after a predetermined time has elapsed after the arrival of the sheet at the position of the registration roller is detected, and then the registration roller is moved in the first direction. Rotates in the opposite second direction and operates the positioning means, subsequently stops the operations of the registration roller and the positioning means, and then rotates the registration roller and the conveyance roller in the first direction. It is equipped with control means for starting.

[0011]

The leading end of the sheet conveyed by the conveying means is brought into contact with the aligning means to align the leading end along the direction orthogonal to the conveying direction, and the side portion of the aligned sheet is moved. By pressing in the direction orthogonal to the carrying direction by the positioning means, the center is positioned at the carrying standard center.

This prevents the image from being biased and transferred onto the sheet even if the sheet is skewed at the time of sheet feeding or conveyance. Further, by positioning the paper center with the aligning means rotated in the reverse direction, friction between the aligning means and the leading end of the paper is reduced.

Therefore, when the side of the paper is pressed,
The paper can be moved smoothly, and the paper center can be surely aligned with the transport reference center. Further, by moving the positioning means according to the size of the paper and pressing the paper, it is possible to center the paper of various sizes.

[0014]

The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 2 shows an electrophotographic apparatus, in which 1 is a main body of the apparatus. A photoconductor drum 2 as an image carrier is rotatably provided in the direction of arrow a on the upper side of the apparatus main body 1. A charging charger 3, an exposure unit 4, a developing device 5, a transfer device, a peeling charger 6, 7, a cleaning device 8, and a charge eliminating device 9 are sequentially arranged around the photosensitive drum 2 along the rotation direction thereof. ing.

Further, a paper feed cassette 11 is provided as a paper feed means on the inner bottom of the apparatus main body 1, and the paper P is accommodated in the paper feed cassette 11 in a stacked state. The paper P in the paper feed cassette 11 is the pickup roller 12
And is conveyed to the image transfer portion 14 between the photosensitive drum 2 and the transfer charger 6 via the conveying path 13. A sheet feed roller 15, a pair of transport rollers 16 as a transport unit, and a detection switch 1 as a detection unit are sequentially provided on the transport path 13 in the transport direction of the sheet.
7, and a pair of registration rollers 18 as alignment means.

Thus, at the time of image formation, the original document is exposed by an exposure device (not shown), and the light reflected from the original document is applied to the surface of the photosensitive drum 2. The surface of the photosensitive drum 2 is charged by the charging charger 3, and the charged surface is irradiated with the above-mentioned light, whereby an electrostatic latent image of the original is formed. This electrostatic latent image is sent to the developing device 5 by the rotation of the photosensitive drum 2, and is visualized by the developer supplied from the developing device 5.

On the other hand, at this time, the paper P is taken out from the paper feed cassette 11 by the rotation of the pickup roller 12, and the paper P is rotated by the rotation of the paper feed roller 15 and the separating plate 15.
and a are separately supplied one by one. The sheet P is conveyed by the rotation of the conveying roller pair 16 and the registration roller pair 1
After being aligned by 8, the image is sent to the image transfer portion 14 between the photoconductor drum 2 and the transfer charger 6, and the electrostatic latent image on the photoconductor drum 2 is transferred by the action of the transfer charger 6. . The sheet P on which the electrostatic latent image is transferred is peeled off from the photosensitive drum 2 by the action of the peeling charger 7, and then the image is fixed and discharged by a fixing device (not shown).

By the way, as shown in FIG. 1, on the sheet carrying-in side of the pair of registration rollers 18, there is provided a positioning means 21 for aligning the center in the direction orthogonal to the carrying direction of the paper P with the carrying standard center. .

That is, reference numerals 22a and 22b in the drawing denote pressing plates arranged at a predetermined interval in the width direction of the paper P. One pressing plate 22a is rotatably attached to the upper end of the support shaft 23. Further, a pair of stopper pins 25, 25 are provided on the upper portion of the support shaft 23 via a mounting tool 24, and the pressing plate 2 is provided by these stopper pins 25, 25.
The rotation amount of 2 is regulated. Above support shaft 2
As shown in FIG. 4, 3 is attached to the swing end of the swing lever 26, and the base end of the swing lever 26 is supported by the rotary shaft 27. A gear 28 is attached to the rotary shaft 27, and a drive shaft 31 of a drive motor 30 is connected to the gear 28 via a gear 29.

The other pressing plate 22b is also constructed and supported in the same manner as the pressing plate 22a, is connected to the drive shaft 31 of the drive motor 30 via the drive belt 33 and the pulley 32, and can be swung. ing.

Further, as shown in FIG. 3, the detection sensor 17 provided on the sheet carrying-in side of the pair of registration rollers 18 is as follows.
The control means 36 is connected to the control means 36. When the detection sensor 17 detects the leading edge of the paper P and a predetermined time elapses, the control means 36 stops the drive motor 37 of the conveyance roller pair 16 and the registration roller pair 18 as well. The drive motor 38 for normal and reverse rotation is reversely rotated.

Further, when the registration roller pair 18 is rotated in the reverse direction, the drive motor 30 of the positioning means 21 is rotated, and after a lapse of a predetermined time, the drive motor 37 of the conveyance roller pair 16 is rotated and the registration roller pair is rotated. The drive motor 38 of 18 is rotated forward.

Next, the leading edge alignment and center alignment of the paper P carried into the registration roller pair 18 will be described. The sheet P is conveyed by the rotation of the pair of conveying rollers 16 as shown in FIG. 5, and when the leading end thereof reaches the pair of registration rollers 18 (during stop), it is detected by the detection sensor 17 and also shown in FIG. As shown in (), the corner of the leading edge of the sheet P contacts the registration roller pair 18. After the detection by the detection sensor 17, the conveying roller pair 1 is operated for a predetermined time.
6 continues to be conveyed and the paper P is conveyed, and as shown in FIG. 6B, the entire width direction of the leading end thereof contacts the pair of registration rollers 18. As a result, the leading edge of the sheet P is aligned along the direction orthogonal to the transport direction. When the position of the leading edge of the sheet is aligned in this way, the rotation of the transport roller pair 16 is stopped and the leading edge alignment is completed.

When the leading edge alignment of the sheet P is completed, the registration roller pair 18 is reversely rotated, and by this reverse rotation,
Friction between the registration roller pair 18 and the leading end of the paper P is reduced. At the time of reverse rotation of the registration roller pair 18,
The drive motor 30 of the positioning means 21 is actuated, and the gear 29
The swing lever 26 is swung via the gear 28, and the pressing plates 22a and 22b are moved toward the sheet P toward the sheet width position for each sheet size, and the sheet P is moved to the sheet width position as shown in FIG. 6C.
Press both sides of. By this pressing, the center C of the sheet P coincides with the transport reference center K and the center position is determined. In this way, when the center position is determined, the rotation of the registration roller pair 18 is stopped, and friction is generated between the registration roller pair 18 and the leading end of the sheet P. From this state, the drive motor 30 is rotated in the reverse direction, the swing lever 26 is swung in the opposite direction, the pressing plates 22a and 22b are separated from the sheet P, and the centering is completed.

As described above, the side surfaces of the sheet P, which is brought into contact with the registration roller pair 18 and the leading end of which is aligned, is pressed by the pressing plates 22a and 22b to smoothly move the center C to the transport standard center K. Since the images are aligned with each other, the original image on the photosensitive drum 2 can be transferred to the paper without being biased, and an excellent image can be formed.

Further, in the state where the pair of registration rollers 18 is rotated in the reverse direction to reduce the friction between the pair of registration rollers 18 and the leading end portion of the sheet P, both side surface portions of the sheet P are pressed by the pressing plates 22a and 22b. The center C can be smoothly adjusted to the transport reference center K.

Further, since the pressing plates 22a and 22b are rotatably provided, the paper P can be pressed along the inclination thereof, and there is no fear that the paper P is deformed by the pressing. Also, the pressing plate 2
Since the rotation amounts of the 2a and 22b are regulated by the stop pins 25 and 25, the surfaces of the pressing plates 22a and 22b can be reliably aligned with the paper P.

[0028]

As described above, according to the present invention,
By bringing the leading end of the sheet conveyed by the conveying unit into contact with the aligning unit, the leading end is aligned along the direction orthogonal to the conveying direction, and the side portion of the aligned sheet is arranged by the positioning unit. By pressing in the direction orthogonal to the transport direction, the center is positioned at the transport reference center, so even if the paper is skewed during its feeding or transport, the image will not be biased and transferred to the center of the paper. It is possible to obtain an image in which the position is matched.

Further, since the sheet center is positioned with the aligning means rotated in the reverse direction, it is possible to reduce friction between the aligning means and the leading edge of the sheet. Therefore, when the side portion of the paper is pressed by the positioning means, the paper can be moved smoothly, and the paper center can be surely aligned with the transport reference center. Further, since the positioning means moves according to the size of the sheet and presses the sheet, it is possible to center the sheets of various sizes.

[Brief description of drawings]

FIG. 1 is a perspective view showing a sheet aligning unit and a positioning unit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an electrophotographic apparatus including the alignment unit and the positioning unit of FIG.

3 is a configuration diagram showing a control system of a registration roller and a conveyance roller of the electrophotographic apparatus of FIG.

FIG. 4 is a plan view showing a drive system of the positioning means of FIG.

5 is a perspective view showing a state in which a sheet is fed to a registration roller by the transport roller of FIG.

6A and 6B show an operation of positioning the center of the sheet sent to the registration roller by the conveyance roller of FIG. 2 at the conveyance reference center. FIG. 6A shows a state in which the leading end of the sheet is in contact with the registration roller. 6 (b) is a diagram showing a state in which the leading end of the sheet is aligned, and FIG. 6 (c) is a diagram showing a state in which the center of the sheet is aligned with the transport reference center by the positioning means. FIG. 9D is a diagram showing a state in which the positioning unit is separated from the sheet after the center of the sheet is aligned with the transport reference center.

[Explanation of symbols]

2 ... Photosensitive drum (image carrier), 6 ... Transfer charger (transfer means), 11 ... Paper feed cassette (paper feed means), P ...
Paper, K ... Conveyance standard center, 16 ... Conveying roller pair (conveying means), 18 ... Registration roller pair (aligning means), 21 ...
Positioning means.

Claims (5)

[Claims] 1. An image carrier for carrying an image, a transfer means for transferring the image carried on the image carrier onto a sheet, and a sheet to be supplied between the transfer means and the image carrier. A paper feeding means for paper, a carrying means for carrying the paper fed by the paper feeding means along a carrying reference center, and a leading end of the paper carried by the carrying means are brought into contact with each other, so that the leading end of the paper is After aligning along the direction orthogonal to the conveying direction, the aligning means for feeding the sheet between the transfer means and the image carrier, and the aligning means aligns the leading end portion of the sheet. An image forming apparatus, further comprising: a positioning unit that presses a side portion of the sheet to position the center of the sheet at the transport reference center. 2. An image carrier for carrying an image, a transfer means for transferring the image carried on the image carrier onto a sheet, and a sheet to be supplied between the transfer means and the image carrier. By feeding the paper feeding means for paper, the transportation means for transporting the paper fed by the paper feeding means along the transportation reference center, and contacting the leading end of the paper transported by the transportation means in a stopped state, Aligning means for feeding the sheet between the transfer means and the image carrier by aligning the leading end of the sheet in a direction orthogonal to the conveying direction, then rotating in the reverse direction, and after a lapse of a predetermined time, rotating in the forward direction. And a positioning means for pressing the sheet in the direction orthogonal to the transport direction of the sheet while the aligning means is rotating in the reverse direction to position the center of the sheet at the transport standard center. Image forming apparatus. 3. An image carrier for carrying an image, a transfer means for transferring the image carried by the image carrier onto a sheet, and a sheet to be supplied between the transfer means and the image carrier. By feeding the paper feeding means for paper, the transportation means for transporting the paper fed by the paper feeding means along the transportation reference center, and contacting the leading end of the paper transported by the transportation means in a stopped state, Aligning means for feeding the sheet between the transfer means and the image carrier by aligning the leading end of the sheet in a direction orthogonal to the conveying direction, then rotating in the reverse direction, and after a lapse of a predetermined time, rotating in the forward direction. While the aligning means is rotating in the reverse direction, it moves in a direction orthogonal to the sheet conveying direction according to the size of the sheet and presses the side portion of the sheet to position its center at the conveying standard center. Positioning means, and An image forming apparatus characterized by. 4. An image carrier for carrying an image, a transfer means for transferring the image carried on the image carrier onto a paper, and a paper to be supplied between the transfer means and the image carrier. By feeding the paper feeding means for paper, the transportation means for transporting the paper fed by the paper feeding means along the transportation reference center, and contacting the leading end of the paper transported by the transportation means in a stopped state, Aligning means for feeding the sheet between the transfer means and the image carrier by aligning the leading end of the sheet in a direction orthogonal to the conveying direction, then rotating in the reverse direction, and after a lapse of a predetermined time, rotating in the forward direction. A positioning means for pressing the paper in a direction orthogonal to the transport direction of the paper to position its center at the transport reference center while the aligning means rotates in the reverse direction; and a paper transported by the transport means. Reaching the orienting means And a detection unit that detects the sheet, and when the detection unit detects the sheet and a predetermined time elapses, and the leading end of the sheet is aligned, the conveyance of the sheet by the conveyance unit is stopped, An image forming apparatus comprising: a control unit that restarts the transport of the sheet by the transport unit when the aligning unit is normally rotated. 5. An image carrier for carrying an image, a transfer means for transferring the image carried on the image carrier onto paper, a carrying roller for carrying the paper, and a space between the carrying roller and the transfer means. And a registration roller for aligning the front end of the sheet conveyed by the conveying roller and then rotating the sheet in the first direction to convey the sheet to the transfer unit; A detection unit that is provided upstream in the paper conveyance direction and that detects the arrival of the paper at the registration roller; and a detection unit that is provided upstream of the registration roller in the paper conveyance direction and that reaches the registration roller by the detection unit. When it is detected, by moving in the direction orthogonal to the paper transport direction, the misalignment in the direction orthogonal to the paper transport direction is corrected and positioned. The positioning means and the detecting means detect the arrival of the sheet at the position of the registration roller, and after a predetermined time, stop the conveyance operation by the conveying means, and then move the registration roller in the first direction. And rotating the positioning means while stopping the operations of the registration roller and the positioning means, and subsequently moving the registration roller and the conveying roller to the first direction.
An image forming apparatus comprising: a control unit that starts rotation in the direction of.