JP2003146489A - Sheet feeder and image forming device with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently correct a skew amount and a positional shift in a sheet width direction even if the skew amount and the positional shift are large. SOLUTION: In this sheet feeder, a first carrying means 22 is disposed on the upstream side of a sheet carrying direction (an arrow K direction), while a second carrying means 23 is disposed on the downstream side. The first and second carrying means 22, 23 respectively have first and second carrying rollers 22a, 23a, and first and second aslant-feeding rollers 22b, 23b abutted on the carrying rollers 22a, 23a aslant. A distance x1 from a guide member 21 restricting a side end of a sheet to the first carrying roller 22a is set to be larger than a distance x2 from the guide member 21 to the second carrying roller 23a. An external diameter d1 of the first carrying roller 22a is set to be larger than an external diameter d2 of the second carrying roller 23a to increase a peripheral speed of the first carrying roller 22a. The sheet carried by the first and second carrying means 22, 23 are applied with a moment M around the second aslant-feeding roller 23b to apply rotation force toward the guide member 21 to the sheet.

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 preventing skewing of a sheet and positional deviation in the width direction, and an image forming apparatus including the sheet conveying apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer or a facsimile, a sheet-like recording material (hereinafter referred to as "sheet") such as paper or transparent film is prevented from being obliquely conveyed in a conveying path. There is known a sheet conveying device provided with a mechanism for carrying out.

FIG. 9 shows a view of a conventional sheet conveying apparatus as seen from above. Note that, in the figure, a guide member that supports the conveyed sheet S from below is omitted. Further, the conveying direction of the sheet S is indicated by an arrow K, the center in the width direction of the sheet S when the sheet S is conveyed straight without being obliquely conveyed is indicated by C (dashed line), and the sheet S is conveyed further. The left side edge facing the direction is indicated by S1.

The sheet conveying apparatus shown in FIG. 1 has a plate-shaped guide member 20 for regulating the position of the side edge S1 of the sheet S. Near the guide member 20, a first conveying means 17 and a second conveying means 18 having substantially the same configuration are arranged on the upstream side and the downstream side in the sheet conveying direction, respectively. First and second transfer means 17, 18
Is a first conveying roller 17a and a second conveying roller 18a that are driven to rotate, and a first obliquely feeding roller 17b and a second obliquely feeding roller 18 that are driven to rotate by being obliquely pressed against these rollers.
b.

The first and second oblique feed rollers 17b and 18b are
First roller holder 17c and second roller holder 1 respectively
It is rotatably held by 8c.
The second roller holders 17c and 18c respectively include the shaft 17
d and 18d are swingably supported, and are biased by a spring (not shown) so that the first and second skew feed rollers 17b and 18b are respectively moved to the first and second transport rollers 17.
It is adapted to come into pressure contact with a and 18a. The two sets of the first and second conveying means 17 and 18 having such a configuration apply the conveying force F to the sheet S to convey the sheet S obliquely toward the guide member 20. The first transporting means 17 and the second transporting means 18 are arranged at the same distance from the guide member 20.

The sheet S is conveyed toward the guide member 20 by the oblique conveying force F, and its side edge S1 is brought into contact with the guide member 20 to correct the skew and the sheet width direction ( The position in a direction orthogonal to the sheet conveying direction) is regulated.

The sheet conveying apparatus as described above is arranged, for example, between the feeding roller and the image forming section in order to correct the deviation of the sheet S set by the user from the normal position. . Further, in a so-called double-sided machine that automatically forms an image on both sides of the sheet S, it is arranged in a re-conveyance path through which the sheet S passes after image formation on the first side. When the sheet S passes through the re-conveyance path, the skew and the position in the sheet width direction are corrected, and then the image is formed on the second surface.

[0008]

However, in the sheet conveying apparatus shown in the above-mentioned conventional example, when the skew amount of the sheet S is large or the positional deviation in the sheet width direction is large, the skew amount and the position thereof are large. There was a problem that the deviation could not be corrected sufficiently.

The present invention has been made in view of the above circumstances, and is a sheet conveying apparatus capable of favorably correcting even a large skew amount and a large positional deviation in the sheet width direction, and the sheet conveying apparatus. An object of the present invention is to provide an image forming apparatus provided with the image forming apparatus.

[0010]

The invention according to claim 1 is
A first conveying unit arranged on the upstream side in the sheet conveying direction, a second conveying unit arranged on the downstream side for conveying a sheet together with the first conveying unit, and the first and second conveying units. In a sheet conveying device including a regulating member that regulates the position of the side edge of the sheet conveyed by the conveying unit, the first conveying unit conveys the sheet in the sheet conveying direction. And a first nip portion which is obliquely contacted with the first transport roller to form a first nip portion, and a force which is directed to the regulating member is applied to the sheet nipped and transported by the first nip portion. The second conveying unit has a second conveying roller for conveying the sheet in the sheet conveying direction, and the second conveying unit obliquely abuts on the second conveying roller. The nip part of the A second skew feed roller that applies a force toward the regulation member to the sheet nipped and conveyed by the second nip portion, and the distance from the regulation member to the first nip portion is the regulation member. Is set to be longer than the distance from to the second nip portion.

According to a second aspect of the invention, in the sheet conveying apparatus according to the first aspect, the peripheral speed of the first conveying roller is set to be higher than the peripheral speed of the second conveying roller. Is characterized by.

According to a third aspect of the present invention, in the sheet conveying apparatus according to the first or second aspect, the contact pressure of the first oblique feeding roller with respect to the first conveying roller is the second conveying roller. Is set to be larger than the contact pressure of the second oblique feed roller with respect to.

The invention according to claim 4 relates to claims 1 to 3.
In the sheet conveying device described in any one of 1 to 3, the area of the first nip portion is larger than the area of the second nip portion.

The invention according to claim 5 relates to claims 1 to 4.
In the sheet conveying device described in any one of 1 to 3, the second oblique feed roller is formed in a spherical shape.

The invention according to claim 6 is the invention according to claims 1 to 4.
In the sheet conveying device described in any one of the above 1, the second oblique feed roller is formed such that an outer diameter of a central portion in the axial direction is larger than an outer diameter of an end portion in the axial direction.

According to a seventh aspect of the present invention, an image forming section for forming an image on a sheet, a conveying path for conveying the sheet supplied to the image forming section, and a sheet conveying apparatus arranged on the conveying path. In the image forming apparatus including the sheet conveying device, the sheet conveying device is the sheet conveying device according to any one of claims 1 to 6.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals in the drawings denote the same configurations or operations, and repeated description thereof will be omitted as appropriate. Further, the following embodiments exemplify a preferred example of the present invention. Therefore, the dimensions, materials, shapes, relative positions, etc. of the components described in these embodiments are intended to limit the technical scope of the present invention to these unless otherwise specified. Not the one.

<Embodiment 1> An example in which the sheet conveying apparatus according to Embodiment 1 of the present invention is used in an electrophotographic laser printer (hereinafter referred to as "image forming apparatus") will be described.

The image forming apparatus A shown in FIG.
A re-conveyance path (conveyance path) 24 for automatically performing printing (image formation) on both the first surface (front surface) and the second surface (rear surface) of the sheet S (for example, paper or transparent film) is provided. There is. Sheet S having an image formed on the first surface (front surface)
After being conveyed to the re-conveyance path 24 and turned upside down, it is supplied again to the image forming section, and image formation is performed on the second surface (back surface).

As shown in FIG. 1, the image forming apparatus A emits a laser beam L based on the obtained image information by a laser scanner (exposure means) 1 and is installed in a process cartridge 2 after charging. Laser light L on the photosensitive drum 3
Irradiate. By this irradiation, the electric charge of the exposed portion is removed and an electrostatic latent image is formed on the photosensitive drum 3. Toner is attached to this electrostatic latent image by a developing device (not shown) to develop it as a toner image.

On the other hand, the sheets S stored in the paper feed cassette 5 are fed by the paper feed roller 6 and the separation pad 7
The sheets are fed while being separated one by one, and are conveyed to the registration rollers 10 and 11 along the guide member 9 by the intermediate conveyance roller 8 and temporarily stopped. The sheet S once stopped in this manner is timed with the toner image on the photosensitive drum 3 by the registration rollers 10 and 11.
It is supplied to the transfer nip portion between the photosensitive drum 3 and the transfer roller (transfer means) 4. The toner image on the photosensitive drum 3 is transferred onto the sheet S supplied to the transfer nip portion by the transfer roller 4.

The sheet S to which the toner image is transferred is further transported to the downstream side, and is heated and pressed by the fixing device 12 having a heat source inside, so that the toner image is fixed. Sheet S
When printing (image formation) only on one side (first side) of
After that, the sheet is conveyed along the guide 16 by the intermediate sheet discharge roller 13a and the intermediate sheet discharge roller 13b, and is discharged onto the upper surface of the image forming apparatus main body by the discharge roller 14. In the above-described image forming apparatus A, the laser scanner 1, the process cartridge 2 including the photosensitive drum 3, the transfer roller 4, and the like form an image forming unit.

Next, both sides of the sheet S (first side and second side)
The case of printing on will be described.

The discharge roller 14 is constructed so that it can be rotated in the normal and reverse directions. Here, the trailing edge of the sheet S on which printing has been completed on the first surface passes through the nip formed by the intermediate discharge rollers 13a and 13b and reaches the position shown by the solid line in FIG. Then, the discharge roller 14 starts the reverse rotation operation. That is, it rotates in the direction opposite to the direction of the arrow that has been rotating so far. The passage of the sheet S is detected by the sensor arm 19 and a photo interrupter (not shown) that detects the movement of the sensor arm 19. That is,
When the sheet S passes through the sensor arm 19, the sensor arm is in the position indicated by the solid line in FIG. 1, and is otherwise in the position indicated by the broken line. The rear end position of the sheet S is detected by detecting this difference in position with a photo interrupter,
The timing for starting the reverse rotation operation of the discharge roller 14 is determined.

By this reverse rotation operation, the sheet S is conveyed downward along the guide 16 and guided to the nip formed by the switch roller 15 and the intermediate paper discharge roller 13a. After that, the sheet S is conveyed to the intermediate sheet discharge roller 13a, and is conveyed by the upstream first conveying means 22 and the downstream second conveying means 23 disposed in the re-conveying path 24 to form an intermediate state. The conveyance roller 8 is reached. First and second transport means 2
When passing the sheets 2 and 23, the skew of the sheet S and the positional deviation in the sheet width direction are corrected by the configuration and the position regulating method described later. After the sheet S reaches the intermediate conveyance roller 8, the toner image is transferred to the second surface by the transfer roller 4 in the same manner as when the image is formed on the first surface, and the fixing device 1
2. The sheet is ejected onto the upper surface of the image forming apparatus main body by the ejection roller 14 through the intermediate sheet ejection roller 13a and the like. This completes the image formation on both sides.

In the image forming apparatus A as described above, the sheet S is generally fed by the sheet feeding roller 6, and the intermediate conveying roller 8, the registration rollers 10 and 11,
While being conveyed by a plurality of rollers such as the transfer roller 4, it may be conveyed in a skewed manner due to misalignment of the roller shafts forming each roller (roller pair). In addition, when the user sets the sheet S on the tray such as the sheet feeding cassette 5, the sheet S may be set at a deviation from the normal position in the width direction. If the sheet S is conveyed to the image forming unit while being displaced, the image will be printed at a position displaced from a desired position as a result.

In particular, when printing is performed on both sides of the sheet S as in the above-mentioned conventional example, such a positional deviation of the image is likely to occur because the conveyance distance until the printing on the second side is long. Therefore, with respect to the width direction of the sheet S, a position regulating unit that regulates the position of the side edge S1 of the sheet S is often provided in the middle of the conveying path.

FIG. 2 is a view of the sheet conveying device according to the first embodiment, which is disposed in the re-conveying path 24, viewed from the upper surface side (upper side). In addition, in the figure, a lower guide member for guiding the sheet S from below is omitted. This point also applies to FIGS. 4, 5, and 6 described later. FIG. 3 is an enlarged view of the vicinity of the re-conveyance path 24 in FIG.

As shown in FIG. 2, the re-conveyance path 24 has
A guide member (regulating member) 21 that regulates the position of the left side end of the sheet S conveyed in the arrow K direction is provided upright. Then, a first conveying means 22 is arranged on the upstream side in the sheet conveying direction, and a second conveying means 23 is arranged on the downstream side of the first conveying means 22. The first and second transporting means 22 and 23 correct the skew and position shift of the sheet S and also serve to re-feed the sheet S as described later.

The first and second transporting means 22 and 23 include a first transporting roller 22a and a second transporting roller 23a which are rotationally driven, and these first and second transporting rollers 22a and 23a.
a is pressed against from above, and these conveying rollers 22a, 2
3a, the first and second nip portions are formed between the first and second nip portions.
And oblique feed rollers 22b and 23b. The skew feed rollers 22b and 23b have first and second conveyance rollers 22 whose axes are perpendicular to the sheet conveyance direction (arrow K direction).
It is arranged obliquely with respect to the axes of a and 23a. The axis of the first oblique feed roller 22b is inclined with respect to the axis of the first transport roller 22a by an inclination angle α, and
The axis of the second oblique feed roller 23b is the same as that of the second transport roller 23a.
It is inclined by an inclination angle β with respect to the axis. In this embodiment, α = β is set. The first and second oblique feed rollers 22b and 23b are rotatably supported by the first and second roller holders 22c and 23c, respectively. The first and second roller holders 22c and 23c are swingably supported by shafts 22d and 23d, respectively, and are biased downward by a biasing member (not shown) such as a spring. As a result, the first and second oblique feed rollers 22
b and 23b are first and second transport rollers 22a and 23a.
Are pressed against each other with an appropriate contact force.

As shown in FIG. 2, in the present embodiment, the first conveying roller 22a is the second conveying roller 2 in the width direction of the sheet S (direction orthogonal to the conveying direction).
It is arranged at a position closer to the center C of the sheet as compared to 2b, and thus at a position farther from the guide member 21 (x1> x2). That is, the first transport roller 22a and the first
The first nip portion between the oblique feed roller 22b and the second nip portion is disposed farther from the guide member 21 than the second nip portion between the second transport roller 23a and the second oblique feed roller 23b. Has been done. Further, the roller diameter d1 of the first conveyor roller 22a is set to be larger than the roller diameter d2 of the second conveyor roller 23a (d1> d2), and the roller diameter d1 is larger than the peripheral speed of the second conveyor roller 23a. The peripheral speed of the first transport roller 22a is increased. Thus, by setting x1> x2 and d1> d2, the first transport roller 22
When the sheet S is conveyed by a and the second conveying roller 23a, the moment S for rotating the sheet S around the second nip portion of the second conveying roller 23a is larger than that in the conventional case. To work. Therefore, the sheet S
Is further rotated toward the guide member 21 while being conveyed.

FIG. 4, FIG. 5, and FIG. 6 are explanatory views of the operation of the sheet conveying apparatus having the above-mentioned structure. In the following, as shown in FIG. 4, for the sheet S in which the left side end S1 of the sheet S is largely deviated from the normal position, skew feeding is corrected and positional deviation in the sheet width direction coexists. explain.

When the sheet S is conveyed by the first conveying roller 22a and the second conveying roller 23a, it is conveyed while rotating little by little in the arrow M direction around the nip portion of the second conveying roller 23a. , Approaching the guide member 21. Then, as shown in FIG. 5, after the left end of the leading edge of the sheet S contacts the guide member 21, the sheet S is rotated by the reaction force from the guide member 21, unlike the contact before the contact. Disappear. Therefore, the sheet S
Is a first transport roller 22a and a second transport roller 23a
By the oblique feeding force by, the oblique feeding is gradually corrected, and the sheet is conveyed in the conveying direction while moving toward the guide member 21 in a movement direction substantially parallel to the parallel movement. Then, as shown in FIG. 6, after the side edge S1 of the sheet S is completely along the guide member, the first and second conveying rollers 22a and 23 are provided.
By the cooperative action of the conveying force of a and the reaction of the guide member 21, the sheet is conveyed straight in the conveying direction.

As described above, according to the present embodiment, at the initial stage of the conveyance by the first conveying roller 22a and the second conveying roller 23a, the sheet S has a larger rotational force in the direction of the arrow M than in the conventional case. Is conveyed in a given state, the guide member 21 approaches and abuts in a short time. Therefore, it is possible to quickly align and convey the sheet S to the correct position.

As is apparent from the above description, according to the present embodiment, even if the skew amount of the sheet S or the deviation in the width direction is large, the skew or the position deviation in the width direction is caused in a short time. Can be corrected. That is, it is possible to provide a sheet conveying device having a high correction capability for skew and positional deviation in the width direction.

In this embodiment, x1> x2,
Although the configuration in which d1> d2 is combined is employed, the corresponding effect can be obtained even if only one of them is configured, that is, x1> x2 and d1 = d2, or x1 = x2 and d1> d2.

<Second Embodiment> The sheet conveying apparatus according to the second embodiment is different from the above-described first embodiment in the shape of the second oblique feed roller of the second conveying means. The other configurations are similar to those of the first embodiment, and thus the description thereof is omitted.

FIG. 7 shows the second carrying means 2 of this embodiment.
3 is a view of the sheet 3 viewed from the upstream side in the sheet conveying direction. As shown in the figure, the second oblique feed roller 31 is formed in a spherical shape. Therefore, the area of the second nip portion formed between the second conveying roller 23a and the second conveying roller 23a is small, and the pressure contact state is close to point contact. Therefore, the conveyed sheet S
Easily rotates around the nip portion of the second oblique feed roller 31. That is, even when the skew feed amount of the sheet and the positional deviation in the width direction are large, these can be corrected well.

Further, the same effect as that of this embodiment can be obtained also by the second oblique feed roller 32 having the shape shown in FIG. As shown in the figure, in the second oblique feed roller 32, the outer diameter d3 of the central portion 32a in the axial direction is set larger than the outer diameter d4 of the end portion 32b. The second oblique feed roller 32 having the shape shown in the figure is also in a state of pressure contact with the second transport roller 23a, which is close to a point contact, in substantially the same manner as the spherical second oblique feed roller 31 described above.

Further, the same effect as this embodiment is
It can also be realized by reducing the pressure contact force for the oblique feed roller in comparison with the pressure contact force for the first oblique feed roller.

In addition, it is preferable that the area of the first nip portion of the first conveying means 22 is larger than the area of the second nip portion of the second conveying means 23. As a result, as compared with the first nip portion for the sheet S, the second
The force applied from the nip portion is reliably transmitted, and the sheet S can be reliably rotated.

[0042]

As described above, according to the present invention,
By setting the distance from the regulating member to the first nip portion to be larger than the distance from the regulating member to the second nip portion, a rotational force centered on the second nip portion is applied to the sheet. Therefore, even if the skew feeding amount and the positional deviation in the sheet width direction are large, the correction can be satisfactorily performed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a top view of the sheet conveying device according to the first embodiment.

3 is an enlarged view of the vicinity of a re-conveyance path in the image forming apparatus of FIG.

FIG. 4 is an operation explanatory diagram of the sheet conveying apparatus according to the first embodiment.

FIG. 5 is an operation explanatory diagram of the sheet conveying apparatus according to the first embodiment.

FIG. 6 is an operation explanatory diagram of the sheet conveying apparatus according to the first embodiment.

FIG. 7 is a diagram showing a second oblique feed roller according to the second embodiment.

FIG. 8 is a diagram showing another second oblique feed roller according to the second embodiment.

FIG. 9 is a top view of a conventional sheet conveying device.

[Explanation of symbols]

21 regulating member (guide member) 22 1st conveyance means 22a 1st conveyance roller 22b 1st skew feeding roller 23 2nd conveyance means 23a 2nd conveyance rollers 23b, 31, 32 2nd skew feeding roller 32a Second oblique feed roller central portion 32b Second oblique feed roller end portion d1 First conveying roller outer diameter d2 Second conveying roller outer diameter d3 Axial center outer diameter d4 Axial end portion Outer diameter x1 distance from the regulating member (guide member) to the first nip portion (first conveying roller) x2 distance from the regulating member (guide member) to the second nip portion (second conveying roller) α Inclination angle β of the first skew feed roller with respect to the first conveyance roller β Inclination angle of the second skew feed roller with respect to the second conveyance roller S sheet S1 side edge of sheet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Miya ▲ Saki ▼ Yoshiyuki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Masafumi Maeda             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 3F049 AA02 CA04 CA16 CA31 DA11                       EA14 LA02 LA05 LA07 LB03                 3F102 AA02 AA10 AA11 AB01 AB05                       BA02 BB04 EA03 EA06 FA02                       FA04

Claims (7)

[Claims] 1. A first conveying means arranged upstream in the sheet conveying direction, a second conveying means arranged downstream and conveying a sheet together with the first conveying means, and these second conveying means. 1. A sheet transporting device comprising: a regulating member that regulates a position of a side edge of a sheet conveyed by a second conveying means, wherein the first conveying means conveys the sheet in a sheet conveying direction. A first conveyance roller and a first nip portion that is obliquely contacted with the first conveyance roller to form a first nip portion, and a force that is directed to the regulation member is applied to the sheet nipped and conveyed by the first nip portion. The first skew feed roller to be given,
And a second transport roller configured to transport the sheet in a sheet transport direction, and a second nip portion that is obliquely contacted with the second transport roller. And a second skew feed roller that applies a force toward the regulating member to the sheet nipped and conveyed by the second nip portion, and a distance from the regulating member to the first nip portion. Is set longer than the distance from the regulation member to the second nip portion. 2. The sheet conveying apparatus according to claim 1, wherein the peripheral speed of the first conveying roller is set to be higher than the peripheral speed of the second conveying roller. 3. The first relative to the first transport roller
The contact pressure of the obliquely feeding rollers is set to be higher than the contact pressure of the second obliquely feeding rollers with respect to the second conveying roller. The sheet conveying device described. 4. The sheet conveying apparatus according to claim 1, wherein the area of the first nip portion is larger than the area of the second nip portion. 5. The sheet conveying device according to claim 1, wherein the second skew feed roller is formed in a spherical shape. 6. The second oblique feed roller is formed so that an outer diameter of a central portion in the axial direction is larger than an outer diameter of an end portion in the axial direction. The sheet conveying device described. 7. An image forming unit for forming an image on a sheet,
An image forming apparatus, comprising: a transport path for transporting a sheet supplied to the image forming unit; and a sheet transport device disposed in the transport path, wherein the sheet transport device is the sheet transport device. An image forming apparatus, wherein the image forming apparatus is the sheet conveying apparatus according to any one of the above.