JP2000233850A - Sheet carrying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet carrying device and an image forming device which are low in price, and capable of efficiently correcting lateral registration only by paired carrying rollers. SOLUTION: When a roller 17 and a second roll pass through a nip after the rear end of a sheet has been fixed, a sheet P receives the resistance of a carrying lower guide so as to be rotated and inclined, in such a way that its rear end is approached to the side of a reference plane 24a. In this case, the sheet P is accelerated to be approached to the reference plane 24a (b) so as to let it finally abut against an intersecting point 24c of the reference plane 24a with a tapered surface 24b, and a reverse rotation is caused by the reaction of the abutment so as to let the tip end of the sheet P approach to the reference plane 24a side, so that the sheet P is matched to a position laid along the reference plane 24a (c).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus for conveying a sheet, and more particularly, to an image forming apparatus such as a printer, a facsimile, a copying machine, etc., which can form a double-sided image of a sheet. .

[0002]

2. Description of the Related Art Conventionally, a laser beam printer 101 shown in FIG. 14 will be described as an example of an image forming apparatus capable of forming a two-sided image of a sheet.

The laser beam printer 101 can form an image on both sides of a sheet as well as on both sides. An image forming section 102 for forming an image and a sheet conveying apparatus for re-feeding the sheet on which one side of the image has been formed are used. And a sheet re-feeding conveyance unit 103.

The image forming unit 102 includes a cassette 104 for stacking sheets and a feeding unit 10 including a feeding roller 106.
5. Process cartridge 10 including photosensitive drum 108
7, a transfer roller 109, a fixing unit 110, a laser scanner unit 112, a sheet discharge section 113 including a sheet discharge stacking table 116, and a controller board 111.

When the controller board 111 receives a print signal, the sheets P stacked on the cassette 104 are separated and fed one by one by a feed roller 106, and a nip between the photosensitive drum 108 and the transfer roller 109, a fixing unit The sheet is conveyed in the order of 110, and an image is formed on one surface of the sheet.

When the controller board 111 has received a signal for one-sided image formation, the sheet P is sent to the sheet discharge section 113 as it is and discharged onto the sheet discharge stacking table 116.

On the other hand, when the controller board 111 has received a signal for forming a double-sided image, the sheet P is continuously sent to the sheet re-feeding / conveying unit 103.

The sheet re-feeding / conveying unit 103 includes a flapper 1
39, the curl removing roller pair 134 and the transport roller pair 13
5 including the transfer path 137 and the switchback roller pair 1
And a switchback unit 138 including
A lateral registration correction unit 123 as a lateral registration correction unit including:
And a re-feed roller pair 122.

Upon receiving the double-sided image forming signal, the flapper 139
Sheet P conveyed to the sheet re-feeding conveyance unit 103 by the
Is sent from the transport path 137 to the switchback unit 138. Here, the switchback roller 136 rotates in the reverse direction, and the sheet P is conveyed to the lateral registration correction unit 123 in a state where the leading and trailing ends are reversed and the sheet P is reversed.

As shown in FIG. 15, the lateral registration correcting unit 123 is disposed on the reference plate 124 and abuts on a predetermined area in the width direction of the sheet P, and has a center axis substantially perpendicular to the reference plate 124. A plurality of rollers 125 and these rollers 125
And a plurality of skew feeding rollers 126 whose central axes are inclined by several degrees with respect to the roller axis, respectively, constitute a pair of rollers 125 and skew feeding rollers 126 as a pair of conveying rollers.

Since the sheet P may be skewed while passing through the image forming unit 102 or may enter the sheet re-feeding / conveying unit 103 in a state of being shifted in the sheet width direction, The horizontal registration correction unit 123 corrects the position of the sheet to a correct position again before forming the image on the second surface. Such correction will be referred to as lateral registration correction hereinafter.

A method of correcting a sheet will be described below with reference to FIG. The sheet P that has reached the lateral registration correction unit 123 is
Since the oblique feeding force is exerted by the inclined oblique feeding roller 126, the oblique feeding roller 126 approaches the reference plate 124 side while being conveyed. Eventually, the sheet side end reaches and abuts the reference plate 124, and the sheet P is conveyed along the reference plate 124, and corrected to a correct position without skew or displacement.

The sheet P corrected in the lateral registration as described above
Is sent again to the image forming unit 2 by the sheet re-feed roller 122 to form an image on the second side, and the sheet discharging unit 11
3 and stacked on the sheet discharge table 116.

The double-sided image forming apparatus shown in the conventional example shown in FIG.
The paper path length up to 22 was sufficient. In such a double-sided image forming apparatus, in order to be able to convey sheets of various lengths, it is necessary to arrange each roller with a span shorter than the minimum length.

Therefore, in this double-sided image forming apparatus, it is necessary to arrange two or more pairs of the roller 125 and the skew roller 126 (transport roller pair) of the lateral registration correction unit 123 in the transport direction.

On the other hand, in order to provide an inexpensive double-sided image forming apparatus, one roller / skew roller pair of the horizontal registration correction unit is provided.
Recently, a configuration in which one is used has been considered. In this double-sided image forming apparatus, the number of sheets that can be conveyed by the sheet re-feeding conveyance unit 3 is limited to A4, LTR, LGL, and the like, and the paper path length is made as short as possible. Is also configured to enable lateral registration correction.

[0017]

However, in order to provide an inexpensive double-sided image forming apparatus, if only one pair of the rollers of the lateral registration correction unit and the pair of conveying rollers composed of the skew rollers are used, the following two problems occur. there were.

First, the first problem will be described. Ordinary roller pairs arranged in the transport direction before and after the roller / skew roller pair are arranged two or more in the width direction or sandwich a long region in the width direction, and the sheet does not skew or shift. Therefore, the effect of the lateral registration correction is greatest when the sheet is nipped and conveyed only by the roller / skew roller pair. That is, it is advantageous for the lateral registration correction that the paper path length between the front and rear normal roller pairs is longer than the sheet length.

However, as described above, if only one pair of rollers and skew rollers are used, the span between the front and rear rollers must be shortened, which is disadvantageous for lateral registration correction.

As a second problem, when a sheet is nipped and conveyed by a pair of rollers and a skew roller pair, the sheet conveyance becomes unstable, so that there is a high possibility that a problem such as a paper break or a scratch is generated. turn into.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide an inexpensive sheet conveying apparatus capable of performing lateral registration correction efficiently using only a pair of conveying rollers. And an image forming apparatus.

[0022]

According to a first aspect of the present invention, there is provided a sheet conveying apparatus including a lateral registration correcting means for correcting a position in a width direction of a sheet to be conveyed. The lateral registration correction means is provided with a reference surface that regulates the sheet side end and corrects the sheet to a predetermined width direction position, and is disposed upstream of the reference surface in the sheet conveyance direction and extends from the width direction outside to the reference surface. A reference plate having a continuous tapered surface, and a pair of conveying rollers for applying a conveying force to the sheet in a predetermined region in the width direction on the reference surface side to rotate the sheet, and I do.

[0023] It is preferable that the pair of transport rollers feed the sheet obliquely toward the reference plate.

It is preferable that the pair of transport rollers include a lateral registration correction roller that is driven to rotate, and a lateral registration correction roller that is pressed against the lateral registration correction roller and is driven to rotate.

It is preferable that the shape of the lateral registration correction roller is a Tyco shape in which a cylindrical generatrix is bulged in the middle.

A re-feeding means disposed downstream of the pair of conveying rollers in the sheet conveying direction for re-feeding the sheet, and regulating the sheet side end just before the re-feeding means to feed the sheet. A second reference surface to be corrected to a predetermined width direction position, and a second tapered surface disposed upstream of the second reference surface in the sheet conveying direction and continuous from the width direction outside to the second reference surface. And a relief portion for allowing the sheet side end to escape outward in the width direction between the reference plate and the second reference plate.

A non-reference guide surface facing the reference surface at a position wider than the maximum sheet width of the sheet to be conveyed and disposed upstream of the pair of conveyance rollers in the sheet conveyance direction; And a non-reference tapered surface that is disposed on the upstream side in the sheet conveyance direction and is continuous from the outside in the width direction to the non-reference guide surface.

It is preferable that the reference plates are provided in multiple stages corresponding to a plurality of sheet widths so that the smaller the sheet width of the conveyed sheet is, the lower the lower stage is.

An image forming apparatus according to the present invention includes the above-described sheet conveying apparatus and an image forming section for forming an image on a sheet.

An image forming apparatus for forming an image on both sides of a sheet, wherein the sheet conveying device is provided in a sheet re-feeding and conveying section for conveying the sheet having an image formed on the first side to the image forming section again. preferable.

[0031]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) A first embodiment will be described with reference to FIGS. The first embodiment is a laser beam printer 1 as an example of a two-sided image forming apparatus.

The laser beam printer 1 can form an image on both sides of a sheet as well as on both sides. An image forming section 2 for forming an image and a sheet re-feeding and conveying section 3 as a sheet conveying device for reversing the sheet. It is a thing which has.

FIG. 1 is a main sectional view showing a laser beam printer 1 according to the present embodiment. Image forming unit 2 using FIG.
Will be described.

A plurality of sheets P can be stacked on the cassette 4. The feeding unit 5 is a unit that separates and feeds the sheets P stacked on the cassette 4 one by one by the sheet feeding roller 6 or the like. The process cartridge 7 integrally includes the photosensitive drum 8 and process means (charging means, developing means, and cleaning means) acting on the photosensitive drum 8 and is detachable from the printer main body.

The transfer roller 9 transfers the toner image formed on the photosensitive drum 8 to a sheet P passing between the photosensitive drum 8 and the transfer roller 9. The fixing unit 10 semi-permanently fixes the toner image on the sheet P to which the toner image has been transferred.

The controller board 11 has a function of controlling the main body of the laser beam printer 1 and performing image forming processing of an image signal of a connected computer (not shown).

The laser scanner unit 12 irradiates the photosensitive drum 8 with a laser beam corresponding to the image signal generated by the controller board 11 to form a latent image.

The post-fixing roller 17 forms a nip with the first roller 18 and conveys the sheet P coming out of the fixing unit 10 along the discharge guide 20 and the flapper 39.

The paper discharge section 13 has a discharge roller 14 and a discharge roller 15 facing each other, and constitutes discharge means. The discharge stacking table 16 is a table that receives the sheet discharged by the discharge roller 14 and the discharge roller 15.

Next, the operation of the image forming section 2 will be described. When the image forming unit 2 receives a print command, the sheets P stacked on the cassette 4 are separated and fed one by one by a paper feed roller 6 and are transferred between the photosensitive drum 8 in the process cartridge 7 and the transfer roller 9 ( Nip).
The print command is generated via the controller board 11 when image information is sent from a personal computer (not shown) or the like.

Along with the print command, a bit image of image information (laser light) is radiated from the laser scanner unit 12 onto the photosensitive drum 8, and a toner image is formed on the photosensitive drum 8 by developing means according to the bit image. You.

The toner image formed on the photosensitive drum 8 is transferred to the sheet P at the nip between the photosensitive drum 8 and the transfer roller 9.
Is transferred to

Then, the sheet P on which the toner image has been transferred
Is sent to the fixing unit 10 and heated and pressed by the fixing unit 10. As a result, the toner image is fixed on the sheet P semipermanently.

After fixing by the fixing unit 10, the sheet P is sent to the nip of the first roller 18 facing the post-fixing roller 17, and is discharged via the discharge guide 20 and the flapper 39.
The sheet is sent to the sheet discharge unit 13.

At this time, the position of the flapper 39 is the position indicated by the solid line in FIG. When the controller board 11 has received a signal for one-sided image formation, the sheet P is nipped and conveyed by the discharge roller 14 and the discharge roller 15 and discharged to the discharge stacking table 16.

Here, the single-sided image forming signal is a signal sent from a personal computer or the like (not shown) to the controller board 11 like the print signal and the image signal.

When the controller board 11 has received a signal for forming a double-sided image, the rear end of the sheet is
After passing through the leading end, the discharge roller 14 rotates in the reverse direction, and the flapper 39 moves to the position indicated by the two-dot chain line in FIG.

Thus, the sheet P is continuously sent to the sheet re-feeding / conveying section 3. The discharge roller 14 is driven by a motor (not shown) independent of other rollers.

Next, the structure of the sheet re-feeding / conveying section 3 will be described with reference to FIGS. FIG. 2 is a plan view of the sheet conveyance path of the sheet re-feeding conveyance unit 3 from the post-fixing roller 17 to the sheet re-feeding roller 22 as viewed from above. FIG. 3 is a cross-sectional view cut by the lateral registration correction port 25.

Here, the sheet re-feeding / conveying section 3 is configured around a conveying path starting from the pair of discharge rollers 14 and reaching a junction 21 with the conveying path from the cassette 4.

In addition to the first roller 18, the second roller 19 faces the post-fixing roller 17 and is urged toward the post-fixing roller 17. The sheet P after sheet reversal is the second roller 1
The nip is sent to the nip formed by the nip 9 and conveyed.

In the present embodiment, the discharge roller 14
The transport path from the pair to the nip of the second roller 19 uses the same transport path as the discharge transport path on the first surface.

Here, two or more post-fixing rollers 17 are provided in the sheet width direction to suppress the rotational movement of the sheet P during conveyance. Further, two or more first rollers 18 and second rollers 19 are provided similarly to the post-fixing roller 17.

A lateral registration correcting section 23 as a horizontal registration correcting means.
Has a reference plate 24 including a reference surface 24a, a pair of transport rollers including a lateral registration correction roller 25 and a skew roller 26 as a lateral registration correction roller, and a transport lower guide 27.

The reference surface 24a is a surface that coincides with the right end position (as viewed from the front of the apparatus) of a sheet having the maximum width conveyed to the sheet re-feeding / conveying section 3. For example, the size of the sheet P conveyed to the sheet re-feeding conveyance unit 3 is A4 · LTR ·
When limited to LGL, the reference surface 24a is located at the same position as the right end of the LTR or LGL size.

The lateral registration correction unit 23 corrects the position of the sheet P that has shifted during conveyance to a predetermined widthwise position along the reference plane 24a before forming the second image (referred to as lateral registration correction). )).

In this embodiment, since the reference of the first surface is the center reference, the A4 size sheet side end and the reference surface 24a
(LTR / LGL ends) are different by 3 mm. Therefore, the lateral registration correction unit 23 also has a role of always moving the A4 size sheet by 3 mm in the sheet width direction.

The reference plate 24 is fixed to the main body of the laser printer 1, and includes a lateral registration correction roller 25, a skew roller holding portion 24g, a sheet side end guide 24d including a reference surface 24a and a tapered surface 24b, and a sheet lower surface. 24f of the guide,
This member is provided with a part 24e of the guide on the upper surface of the sheet and the like.

Since the sheet side end guide 24d is shaved by the sheet end, a metal pin 24h is arranged as shown in FIG.

Further, the sheet side end guide 24d is moved from the intersection 24c on the upstream side of the lateral registration correcting roller 25 to the tapered surface 24d.
b. The opening amount of the tapered surface 24b opening outward in the width direction is about 5 mm from the reference surface 24a. The position of the intersection 24c between the reference surface 24a and the tapered surface 24b will be described later in detail.

The lateral registration correction roller 25 is held on the reference plate 24 via a bearing 28, and holds the sheet in a predetermined area in the width direction. Further, it is arranged such that its rotation axis is perpendicular to the transport direction.

The skew feeding roller 26 is rotatably held by the reference plate 24 and is urged by the lateral registration correction roller 25 by a spring 29 to form a nip. The rotation axis of the skew feeding roller 26 is positioned on the reference surface 2 with respect to the rotation axis of the lateral registration correction roller 25.
It is arranged so as to have an inclination of about 7 ° toward 4a. As shown in FIG. 3, the shape of the oblique feeding roller 26 is a so-called Tyco shape in which a cylindrical generatrix expands at the center in the width direction.

The position in the sheet width direction of the lateral registration correction roller 25 and the skew feeding roller 26 is closer to the right end as viewed from the front of the apparatus as the reference surface 24a. In this case, the position near the right end is at least on the right end side with respect to the sheet width １ ／.

In this embodiment, the horizontal registration correction roller 25
And only one pair of transport rollers composed of the oblique feed rollers 26 are provided. Therefore, the position of the pair of the lateral registration correction roller 25 and the skew feeding roller 26 in the transport direction is within the minimum length of the sheet passed from the post-fixing roller 17 and the second roller pair 19.

In the present embodiment, the position of the reference plate 24 is on the right side when viewed from the front of the apparatus.
Even if it is placed on the left side when viewed from the front of the apparatus together with the 5 and the oblique feed rollers 26, the characteristics of the invention are not spoiled. Also, for example, FIG.
The vertical arrangement relationship between the lateral registration correction roller 25 and the skew feeding roller 26 may be reversed.

The lower conveyance guide 27 guides most of the lower side of the sheet conveyance surface. In the present embodiment, the lower conveyance guide 27 is formed of a grounded metal so that electric charges do not accumulate on the conveyed sheet P and problems in conveyance and image formation do not occur.

On the downstream side of the lateral registration correcting section 23, a re-feeding means for forming a nip between the re-feed roller 22 and the roller 30 facing the re-feed roller 22 and re-feeding the paper is provided.

Two or more re-feed rollers 22 are provided in the sheet width direction so that the sheet P corrected in the lateral registration does not skew again. Lower conveyance guide 27 of the lateral registration correction unit 23
Upper and lower frame members 31 including a guide for connecting the pair of sheet re-feed rollers 22 hold rollers 30 facing the sheet re-feed rollers 22 at the same time.

The position of the re-feed roller 22 in the transport direction is within the range of the minimum sheet length from the lateral registration correction roller 25.
Downstream of the re-feed roller 22, there is a junction 21 with the cassette feed path on the first surface.

Next, the operation of the sheet re-feeding / conveying section 3 will be described. When the double-sided image forming signal is received, the position of the flapper 39 moves to the position indicated by the two-dot chain line in FIG. And the discharge roller 15 rotates in the reverse direction.

The sheet P is nipped and conveyed by the post-fixing roller 17 and the second roller 19 with the front and rear ends reversed, and conveyed to the lateral registration correction unit 23. The lateral registration correction method will be described later in detail.

The sheet P subjected to the lateral registration correction is sent again to the image forming unit 2 by the re-feed roller 22 to form a second image whose writing position is adjusted based on the reference surface 24a. Sent to the sheet discharge table 1
6 is loaded.

The method for correcting the lateral registration of the sheet P will be described below. First, FIG. 4 and FIG. 5 illustrate a case where the sheet P is conveyed to the lateral registration correction unit 23 while being separated from the reference surface 24a.
This will be described with reference to FIG.

The leading end of the sheet P conveyed to the lateral registration correcting section 23 by the post-fixing roller 17 eventually reaches the pair of the lateral registration correcting roller 25 and the skew roller 26. In a state where the rear end of the sheet P is held between the nip of the post-fixing roller 17 and the second roller 19, only the front end of the sheet P approaches the reference surface 24a due to the oblique feeding force of the oblique feeding roller 26 (FIG. 4 ( a)).

Thereafter, the rear end of the sheet is fixed to the post-fixing roller 17.
After passing through the nip of the second roller 19, the sheet P is rotated by the resistance of the lower conveyance guide 27 so that the rear end of the sheet P approaches the reference surface 24a. Since the sheet P is tilted by this rotation, the sheet P further approaches the reference surface 24a (FIG. 4).
(B)).

The sheet P has a reference surface 24 a and a tapered surface 24.
4b, the reaction force causes reverse rotation of the sheet P so that the leading end of the sheet P approaches the reference surface 24a, and the sheet P is aligned with the position along the reference surface 24a (FIG. 4).
(C)).

Here, if the sheet P is tilted too much due to the rotation operation, there are many problems that the conveyance becomes unstable and the leading edge or the trailing edge hits another member to cause corner breakage. The inclination of the sheet P with respect to the conveyance direction due to the rotation of the sheet P is empirically limited to 20 °. In addition, if the inclination is small, the shift performance deteriorates. Therefore, at least the inclination needs to be 3 ° or more.

The inclination of the sheet P is determined by two factors: (1) the amount of deviation from the reference surface 24a, and (2) the position of the intersection 24c between the reference surface 24a and the tapered surface 24b.

For example, when a sheet P of A4 size is considered, even if the sheet P is completely conveyed straight until it enters the lateral registration correction unit 23, the shift amount is 3 mm.
It is. This is because the reference surface 24a matches the end surface of the LTR as described above. The displacement due to conveyance caused by the displacement of 3 mm is approximately 5 mm in experience, and when added together, a displacement of up to 8 mm occurs.

In order to maintain the inclination of the sheet P in the conveying direction at an angle of 3 ° to 20 ° with respect to the maximum displacement amount of 8 mm, as shown in FIG. 5, the reference surface 24a and the tapered surface 24b are required. Must be located 20 mm to 150 mm before the lateral registration correction roller 25 in the transport direction.

Here, the lateral registration correction ability can be slightly reduced by performing the lateral registration correction only by the rotation operation of the sheet P without relying on the skew feeding force of the skew feeding roller 26. In this case, the skew feeding roller 26 may be a normal roller provided in parallel with the lateral registration correction roller 25.

Further, in the present embodiment, the shape of the oblique feeding roller 26 is a Tyco shape in which the cylindrical generatrix expands at the center.
The sheet P is easily rotated, and as a result, the efficiency of the skew correction is increased. However, even if the cylindrical generatrix of the oblique feeding roller 26 has a straight cylindrical shape, the characteristics of the present embodiment are not significantly impaired. Next, a case where the sheet P is shifted outward in the width direction from the reference surface 24a and is conveyed to the lateral registration correction unit 23 so as to hit the reference surface 24a will be described with reference to FIG.

Assuming that a deviation of 5 mm occurs in the sheet P in the direction of the reference plane 24a before the sheet P is conveyed to the lateral registration correction unit 23, the LTR or LGL size sheet P is conveyed so as to hit the reference plane 24a by 5 mm. Sometimes.

Here, the tapered surface 2 having an opening amount of 5 mm or more
4b, and the sheet side end guide 24d is configured to shift the leading end of the sheet P by the tapered surface 24b, as shown in FIG. 6, the sheet P follows the tapered surface 24b, and finally the reference surface 24a. Along.

As described above, in the present embodiment, the cost can be reduced with a simple configuration, and the sheet P conveyed by being shifted to the lateral registration correcting section 23 can be efficiently aligned with the reference surface, and the folded sheet and the sheet Problems such as damaging P can be prevented.

(Second Embodiment) A second embodiment will be described with reference to FIGS. The image forming unit 2 of the present embodiment is the same as that of the first embodiment, and the sheet re-feeding / conveying unit 3 is the same except for the configuration of the horizontal registration correcting unit 23, and these same configurations are the same. The description is omitted by attaching reference numerals.

Hereinafter, a specific configuration of the lateral registration correcting section 23 in this embodiment will be described with reference to FIG. FIG.
FIG. 4 is a plan view of a sheet conveying path of the sheet re-feeding and conveying unit 3 from the post-fixing roller 17 to the sheet re-feeding roller 22, which is developed from a plane and viewed from above.

In the present embodiment, the configuration on the downstream side of the reference plate 24 is determined in more detail than in the first embodiment. The reference surface 24 a is about 30 to 30 downstream of the lateral registration correction roller 25.
It is provided up to a position of 40 mm, and a flank 24i having a flank is provided downstream from the position. The flank 24i is a surface escaping 3 mm or more outside the reference surface 24a, and a flank portion is provided in the escaping portion.

A frame reference surface 31a serving as a second reference surface is provided on a frame member 31 serving as a second reference plate before the re-feed roller 22 and a frame taper surface serving as a second taper surface is provided upstream of the frame reference surface 31a. 31b is provided.

The frame reference surface 31a is located at substantially the same position as the reference surface 24a in the sheet width direction. That is, LT
This is almost the same position as the end of the sheet P of the R or LGL size.

In this embodiment, the frame reference plane 31a
Is provided with a length of about 15 mm in the sheet feeding direction,
The taper angle of the frame taper surface 31b is 10 ° to 20 °.
° and the opening of the taper is about 5 mm.

The operation of the present embodiment will be described with reference to FIG. Also in the present embodiment, the method of lateral registration correction is the same as in the first embodiment. However, in the state where the lateral registration correction is completed and the sheet P is being conveyed along the reference surface 24a, the skew feeding force of the skew feeding roller 26, the rotational force described in the first embodiment, and the like are applied to the sheet P. Therefore, the sheet P may be slightly bent before the leading end of the sheet P reaches the re-feed roller 22, and may be skewed again.

In this embodiment, as shown in FIG. 8A, the front end of the sheet P on which the frame tapered surface 31b is skewed immediately before the re-feed roller 22 is scooped, and the frame reference surface 3
At 1a, the position of the leading end of the sheet P can be corrected and adjusted to the correct position again.

Further, the leading edge of the sheet P is the horizontal registration correction roller 2
After being sandwiched between the nip of the roller 5 and the skew roller 26, the sheet P strikes the reference surface 24a by the skew feeding force of the skew roller 26. At this time, as shown in FIG. Therefore, interference between the corner of the leading end of the sheet P and the reference surface 24a can be avoided, and the sheet P can be prevented from being broken or the like.

As in the present embodiment, the frame reference plane 3
By providing the flank 1a and the flank 24i, it is possible to prevent the sheet P from being broken before the re-feed roller 22 and to perform the lateral registration correction reliably.

(Third Embodiment) A third embodiment will be described with reference to FIGS. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Hereinafter, a specific configuration of the lateral registration correction unit 23 in the present embodiment will be described with reference to FIG. FIG.
FIG. 4 is a plan view of a sheet conveying path of the sheet re-feeding and conveying unit 3 from the post-fixing roller 17 to the sheet re-feeding roller 22, which is developed from a plane and viewed from above.

In this embodiment, the non-reference side opposite to the reference plate 24 in the width direction across the sheet P is determined in more detail than in the first and second embodiments. The reference plate 24 is disposed on the right side when viewed from the front of the device, and the non-reference plate 32 is disposed on the non-reference side on the left side when viewed from the front of the device.

The non-reference plate 32 has a non-reference tapered surface 32b on the upstream side, a non-reference guide surface 32a downstream of the non-reference tapered surface 32b, and a flank 32c further downstream.

The non-reference guide surface 32a is arranged 2-3 mm outside the sheet P having the maximum width on the non-reference side. For example, assuming that the maximum width of the sheet P is LTR and LGL, the non-reference guide surface 32a is 21
It is arranged at a position of 8 to 219 mm.

To prevent the non-reference guide 32 from hindering the rotation of the sheet P, a flank 32c is provided to avoid interference between the sheet P and the non-reference guide 32 when the sheet P rotates, and the non-reference guide surface 32a is provided. It must be provided upstream of the lateral registration correction roller 25 in the transport direction.

The operation of the present embodiment will be described with reference to FIG. The sheet P having the maximum width is 2 from the reference surface 24a.
When the sheet P enters the lateral registration correction unit 23 at a distance of about 3 mm or more, the leading end of the sheet P abuts on the non-reference tapered surface 32b, and the sheet P is forced to move toward the reference surface 24a.

The sheet P strikes the reference surface 24a due to this effect, the effect of the oblique feeding force of the oblique feeding roller 26, and the effect of the rotation of the sheet P.

This embodiment is particularly effective for correcting the lateral registration more efficiently for the sheet P having the maximum width that can be conveyed. Then, for example, the sheet P having the maximum width is LTR / LG.
With the L size, the lateral registration correction can be particularly effectively performed for the LGL size having a long sheet length.

(Fourth Embodiment) A fourth embodiment will be described with reference to FIGS. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The specific configuration of the lateral registration correcting section 23 in the present embodiment will be described below with reference to FIGS. FIG. 11 is a sectional view of the laser beam printer according to the present embodiment. FIG. 12 is a plan view of the sheet conveyance path of the sheet re-feeding conveyance unit 3 from the post-fixing roller 17 to the re-feeding roller 22 as viewed from above. FIG. 13 is a cross-sectional view near the lateral registration correction roller 25.

In the present embodiment, a reference plate 33 provided with two reference surfaces 33a and 33d is used for the lateral registration correcting section 23.

The first reference plane 33a is the position of the sheet having the maximum width conveyed to the sheet re-feeding conveyance section 3 (as viewed from the front of the apparatus).
This is the surface that coincides with the right end position. For example, in this embodiment, if the size of the sheet P conveyed to the sheet re-feeding conveyance unit 3 is limited to B5 / EXE / A4 / LTR / LGL, the first reference surface 33a is located on the right side of the LTR or LGL size. The sheet P is provided at the same position as the edge (hereinafter, the size of the conveyed sheet P will be described as being limited).

The second reference plane 33d is located about 16 mm inside the apparatus from the first reference plane 33a. This is the same position as the right end of the EXE size. Also, the second reference plane 33
d is located lower than the first reference plane 33a, as shown in FIG.

33b and 33e are the first and second reference planes 33a,
33d are the first and second tapered surfaces. The intersection between the first tapered surface 33b and the first reference surface 33a is 33c, and the intersection between the second tapered surface 33e and the second reference surface 33d is 33f.

On the upstream side of the reference plate 33, first and second sheet lower surface guides 33g and 33h are provided. Second sheet lower surface guide 33 with respect to first sheet lower surface guide 33g
h is arranged inside the apparatus and at the lower stage. The boundary line 33i in the sheet width direction is near the middle line of the right end of the A4 sheet and the right end of the B5 sheet.

The positions of the lateral registration correction roller 25 and the skew feeding roller 26 in the sheet width direction are arranged inside the apparatus with respect to the second reference surface 33d. For example, this position is provided about 20 mm from the right end of the LTR inside the apparatus. Since the LTR sheet width is 218 mm, the positions of the lateral registration correction roller 25 and the skew feeding roller 26 are the same as in the first to third embodiments.
It can be said that the sheet P of the R size is also at the right end.

Next, the operation of the present embodiment will be described.
First, a case where a sheet P of A4 / LTR / LGL size is conveyed to the sheet re-feeding / conveying section 3 will be described.
When the sheet P having such a width is conveyed to the reference plate 33, the sheet side end is located outside the apparatus with respect to the boundary line 33i. Therefore, the sheet P is guided by the first sheet lower surface guide 33g, and the first reference surface 33a is moved. It is guided to the upper stage provided. Sheet P
When the sheet P enters inside away from the first reference surface 33a, the sheet P hits the first reference surface 33a due to the oblique feeding force of the oblique feeding roller 26 and the rotation operation of the sheet P.

If the sheet P is shifted outward in the width direction so as to hit the first reference surface 33a, the first
In the same manner as in the first embodiment, the first tapered surface 33b scoops up and finally follows the first reference surface 33a.

Next, B5, EXE
A case where a sheet P having a size is conveyed will be described. When the sheet P having such a width is conveyed to the reference plate 33, the end of the sheet P is located inside the apparatus from the boundary line 33i. Therefore, the sheet P is guided by the second sheet lower surface guide 33h, and the second reference surface 33d. Is guided to the lower side.

When the sheet P enters inside away from the second reference surface 33d, the sheet P is moved to the first reference surface 33a by the oblique feeding force of the oblique feeding roller 26 and the rotating operation of the sheet P.
Hit.

If the sheet P is shifted outward in the width direction so as to hit the second reference surface 33d, the second
It is skimmed by the tapered surface 33e, and finally follows the second reference surface 33d.

In the image formation on the second surface of the sheet P, the controller board 11 determines which of the first reference surface 33a and the second reference surface 33d is used depending on the sheet size, and based on this determination, the laser The laser writing position of the scanner 12 is adjusted.

In the present embodiment, the reference plate 33 is provided in a two-stage configuration having two reference surfaces. However, the reference plate 33 has three or more reference surfaces in order to correspond to the sheet width of sheets of other sizes. A multi-stage configuration may be used.

As described above, according to the present embodiment, various sheet widths can be accommodated by the multi-stage reference plate 33.
Even a sheet conveyed shifted from the reference plane can be efficiently aligned with the reference plane according to the sheet size.

[0122]

As described above, according to the present invention, a sheet conveyed by a pair of conveying rollers for applying a conveying force to a sheet in a predetermined region in the width direction on the reference surface rotates to rotate on the reference surface. Since the sheets are copied, the lateral registration correction can be efficiently performed only by the pair of the conveying rollers, and the cost can be reduced by simplifying the configuration by using only the pair of the conveying rollers. Further, a tapered surface which is arranged on the upstream side of the reference surface in the sheet conveying direction and is continuous from the outside in the width direction to the reference surface can shift the sheet conveyed while being shifted to the outside in the width direction.

When the sheet is obliquely fed by the pair of conveying rollers toward the reference plate, the sheet can be more efficiently made to follow the reference surface.

Since the lateral registration correction roller is formed in the shape of a cylinder in which the cylindrical generatrix is bulged, the sheet can be efficiently rotated and the sheet can be made to conform to the reference plane.

The provision of the second reference plate and the escape portion enables reliable lateral registration correction before the sheet reaches the re-feeding means.

Since the non-reference plate is provided opposite to the reference plate with the sheet interposed therebetween, the lateral registration correction of the sheet having the maximum width that can be conveyed can be reliably performed.

Since the reference plates are provided in multiple stages in accordance with a plurality of sheet widths, it is possible to perform lateral registration correction optimal for each sheet width.

In the image forming apparatus of the present invention, the lateral registration correction can be reliably performed in the re-feeding conveyance section for conveying the sheet on which the image formed on the first side is again transferred to the image forming section, and the image on the second side is favorably moved to the optimum position. In addition, it is possible to prevent the sheet from being broken or damaged.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating a lateral registration correction unit according to the first embodiment.

FIG. 3 is a cross-sectional view illustrating the vicinity of a lateral registration correction roller according to the first exemplary embodiment.

FIG. 4 is a diagram illustrating lateral registration correction according to the first embodiment.

FIG. 5 is a diagram illustrating lateral registration correction according to the first embodiment.

FIG. 6 is a diagram illustrating lateral registration correction according to the first embodiment.

FIG. 7 is a diagram illustrating a lateral registration correction unit according to a second embodiment.

FIG. 8 is a diagram illustrating lateral registration correction according to a second embodiment.

FIG. 9 is a diagram illustrating a lateral registration correction unit according to a third embodiment.

FIG. 10 is a diagram illustrating lateral registration correction according to a third embodiment.

FIG. 11 is a cross-sectional view illustrating an image forming apparatus according to a fourth embodiment.

FIG. 12 is a diagram illustrating a lateral registration correction unit according to a fourth embodiment.

FIG. 13 is a diagram illustrating lateral registration correction according to a fourth embodiment.

FIG. 14 is a cross-sectional view illustrating a conventional image forming apparatus.

FIG. 15 is a diagram showing a conventional lateral registration correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam printer 2 Image forming part 3 Sheet re-feeding conveyance part 22 Re-feeding roller 23 Horizontal registration correction part 24 Reference plate 24a Reference surface 24b Tapered surface 24c Intersection point between reference surface and tapered surface 24i Escape surface 25 Horizontal registration correction Roller 26 Oblique feed roller 31 Frame member 31a Frame reference surface 31b Frame taper surface 32 Non-reference plate 32a Non-reference guide surface 32b Non-reference taper surface 33 Reference plate 33a First reference plate 33b First taper surface 33d Second reference plate 33e 2 tapered surface

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H028 BA06 BA09 BA16 BB02 2H072 BB08 CA01 CB07 HB09 3F102 AA07 AA10 AA11 AB01 BA02 BB04 DA02 DA14 EA02 FA01

Claims (9)

[Claims] 1. A sheet conveying apparatus comprising a lateral registration correcting means for correcting a position of a sheet to be conveyed in a width direction, wherein the lateral registration correcting means regulates a sheet-side end and moves the sheet to a predetermined width direction position. A reference plate having a reference surface to be corrected, a tapered surface disposed upstream of the reference surface in the sheet conveyance direction and continuous from the width direction outside to the reference surface, and a predetermined width direction region on the reference surface side A pair of conveying rollers for applying a conveying force to the sheet and rotating the sheet,
A sheet conveying device comprising: 2. A sheet conveying apparatus according to claim 1, wherein said pair of conveying rollers feeds the sheet obliquely toward said reference plate. 3. The pair of transport rollers includes a lateral registration correction roller that is driven and rotated, and a lateral registration correction roller that is pressed against the lateral registration correction roller and is driven to rotate. 3. The sheet conveying device according to 1 or 2. 4. The sheet conveying apparatus according to claim 3, wherein the shape of the lateral registration correction roller is a Tyco shape in which a cylindrical generatrix is bulged in the middle. 5. A re-feeding means disposed downstream of the pair of conveying rollers in the sheet conveying direction for re-feeding a sheet, and regulating a sheet side end just before the re-feeding means. A second reference surface for correcting the sheet to a predetermined width direction position; and a second reference surface disposed upstream of the second reference surface in the sheet conveyance direction and continuous from the width direction outside to the second reference surface. A tapered surface,
3. A second reference plate having: a release portion that releases a sheet side end outward in the width direction between the reference plate and the second reference plate. 5. The sheet conveying device according to 3 or 4. 6. A non-reference guide surface facing the reference surface at a position wider than the maximum sheet width of a sheet to be conveyed and disposed upstream of the pair of conveyance rollers in the sheet conveyance direction. 6. A non-reference plate having a non-reference tapered surface disposed upstream of the guide surface in the sheet conveying direction and continuous from the width direction outside to the non-reference guide surface. The sheet conveying device according to any one of the above. 7. The multi-stage reference plate according to claim 1, wherein the reference plate is provided in multiple stages so as to be regulated at a lower stage as the sheet width of the conveyed sheet is smaller.
7. The sheet conveying device according to any one of items 1 to 6, wherein 8. An image forming apparatus, comprising: the sheet conveying device according to claim 1; and an image forming unit that forms an image on a sheet. 9. An image forming apparatus for forming an image on both sides of a sheet, wherein the sheet conveying device is provided in a re-feeding conveying section for conveying the sheet on which the image is formed on the first side to the image forming section again. The image forming apparatus according to claim 8, wherein: