JPH0912182A - Sheet carrier and image forming device - Google Patents

Abstract

PURPOSE: To deal with the wide range of sheet sizes while taking advantage of a one-side reference by moving a horizontal registration adjusting means to a sheet side end position corresponding to a center reference against a sheet to be carried. CONSTITUTION: A horizontal registration adjusting means 15 is moved in the width direction by a signal from a control part and placed under standby slight outside more than an end part position corresponding to the size of a carried recording sheet. Then, the recording sheet is carried by skew feed roller pairs 15b1 to 15b3 and 15c1 to 15c3, one side end is butted against an end part reference guide 15a, the recording sheet is carried with the position of one side end corrected and the rotations of the rollers are stopped when the sheet tip is detected by a tip detecting means 16. Then, the horizontal registration adjusting means 15 is moved and the recording sheet is positioned so that one side end thereof is more accurately positioned in a specified position by the end part reference guide 15a. Then, all the rollers are rotated and the recording sheet is carried being guided by R path guiding members 21a and 21b and a front guiding member 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device used in a double-sided printing device, an overlapping printing device, etc., and an image forming apparatus using the sheet conveying device.

[0002]

2. Description of the Related Art In an image forming apparatus or the like, a sheet is conveyed along a certain standard so that the sheet is conveyed to a predetermined image forming position. This standard includes a center standard and a one-sided standard. The center reference conveys the sheet such that the center of the sheet in the width direction is always at a constant reference position, and the one-side reference conveys the sheet in the width direction such that one end of the sheet abuts against the guide member and the one end is conveyed. The sheet is conveyed so that it is located at a fixed reference position.

As shown in FIG. 6, for example, the one-sided reference is provided with an oblique feeding roller 51 near the abutting reference member 50 so that the sheet 52 is conveyed by the obliquely feeding roller 51 and one end thereof is abutted. The seat position is set by abutting against the reference member 50. This one-sided reference has the advantage that it is easy to construct and can be provided at low cost.

[0004]

However, in the above-mentioned one-sided reference structure, as shown in FIG.
Depending on the sizes of B and C, the sheet conveying position is biased, and when a small size sheet is conveyed on the basis of one side corresponding to a large sheet size, the other side is largely vacant. Therefore, in the image forming apparatus or the like, the temperature rise on the non-reference side of the fixing device and in the image forming apparatus using the toner cartridge, the toner in the cartridge is likely to be biased.

Further, when a large-sized sheet is conveyed with one side as a reference, when the sheet is conveyed in a bent manner such as a U-turn conveyance, it cannot hit the reference member.
There is a risk of skewing.

The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a sheet conveying device and the like which can accommodate a wide range of sheet sizes while taking advantage of the one-sided reference.

[0007]

A typical structure according to the present invention for achieving the above object is to guide one side end of a sheet in a sheet conveying apparatus which conveys a sheet with a center position of the sheet as a reference. And an oblique feed roller for feeding the sheet so that one end of the sheet comes into contact with the end reference guide, and is movable in a direction orthogonal to the sheet feeding direction. A lateral registration adjusting means, a leading edge detecting means for detecting a leading edge of the sheet positioned and transported by the lateral resist adjusting means, a transporting means for transporting the sheet detected by the leading edge detecting means, and the transporting means. A guide member for guiding the conveyed sheet is provided.

[0008]

In the above structure, the lateral registration adjusting means is moved to the side end position of the sheet corresponding to the center reference with respect to the conveyed sheet, so that the center reference sheet is conveyed by the one side reference configuration. Be seen. Then, the sheet is fed by the subsequent feeding means without skewing even on the curved feeding path.

[0009]

【Example】

[First Embodiment] Next, a first embodiment of the present invention will be described with reference to FIGS. 1 is a schematic configuration explanatory view of an image forming apparatus using a sheet conveying device, FIG. 2 is a schematic perspective view of a sheet conveying device according to the present invention, and FIG. 3 is a schematic diagram of a guide structure according to a sheet size. FIG. Here, as the order of description, the overall configuration of the image forming apparatus using the sheet transporting device will be described first, and then the configuration of the sheet transporting device for retransmitting a sheet will be described.

<Overall Structure of Image Forming Apparatus> As shown in FIG. 1, this image forming apparatus irradiates a drum-shaped electrophotographic photosensitive member with information light based on image information from an optical system 1 to cause the photosensitive member to be exposed. A latent image is formed on the toner image, and the latent image is developed to form a toner image. Then, in synchronization with the formation of the toner image, the recording sheets 3 stored in the cassette 2 are separated and fed one by one by a separation claw 2a and a pickup roller 4a provided at the front end of the cassette 2, and these are conveyed by a pair of conveyance rollers 4b. A toner image formed on the photoconductor drum 5 which is the electrophotographic photoconductor, which is conveyed as a process cartridge by a registration roller pair 4c and the like, and a voltage is applied to a transfer roller 6 as a transfer unit. Is transferred onto the recording sheet 3. Then, the recording sheet 3 after the image transfer is conveyed to the fixing unit 7, and the transferred toner image is fixed on the recording sheet 3. Then, in the case of single-sided recording, the recording medium 3 is discharged to the discharge portion 8 by the discharge roller pairs 4d and 4e.

The recording sheet 3 is set on the basis of the center when fed from the cassette 2, and the image is formed on the basis of the center when forming an image.

On the other hand, in the case of double-sided recording, the flapper 9 is swung to the state shown by the broken line in FIG.
Send to 10. A reversing sensor 11 also serving as a flapper is provided at the entrance of the reversing path 10. When the reversing sensor 11 detects the leading edge of the recording sheet 3, the reversing roller 12 rotates to feed the recording sheet 3 into the reversing path 10. When the sensor 11 detects the rear end of the recording sheet 3, the sensor 11 swings to the state shown by the broken line in FIG. 1 and the reversing roller 12 rotates in the reverse direction, and the image is retransmitted with the image recording surface of the recording sheet 3 facing up. Send to Route 13.

The recording sheet 3 sent to the resending path 13 is conveyed by a pair of conveying rollers 14 and a lateral registration adjusting means 15 is also provided.
The left end of the sheet in the width direction is positioned by, and when the front end of the sheet is detected by the front end detecting means 16, the sheet is conveyed by the first conveying roller pair 17, the second conveying roller pair 18, etc., and conveyed again to the image forming section, An image is formed on the back surface and discharged to the discharge unit 8.

{Sheet Conveying Device} Next, the structure of the sheet conveying device for retransmitting the recording sheet 3 will be described.
This sheet conveying device is provided with the lateral registration adjusting means 1 described above.
5, tip detecting means 16, first and second conveying roller pairs 17, 18
And so on.

As shown in FIG. 2, the lateral registration adjusting means 15 is an end reference guide for abutting and positioning one widthwise side end of the recording sheet 3 conveyed on the lower guide member 20.
15a is provided, and skew feed rollers 15b1, 15b2, 15b3 are provided near the guide 15a (in FIG. 2, roller 15b is provided).
(Only 2,15b3 shown). Rollers 15c1, 15c2 and 15c3 are pressed against the skew feed rollers 15b1 to 15b3 by a leaf spring 15f to form a pair of skew rollers. Further, the oblique transfer rollers 15b1 to 15b3 are respectively provided with drive transmission members 15g1, 15g2, 15
g3 is fixed, and the respective members 15g1, 15g2, 15g3 are connected by a belt 15h. A drive gear 15i is connected to one drive transmission member 15g3 so that the drive force from a motor (not shown) is transmitted to each of the skew feed rollers 15b1 to 15b3.

Further, the drive gear 15i is slidably attached to a D-cut drive shaft 15j, and the end reference guide 15a and skew feed roller pairs 15b1 to 15b3, 15c1 to 15c1.
The reference numeral 15c3 is slidable in a direction orthogonal to the conveying direction of the recording sheet 3 (direction of arrow a in FIG. 2) by a moving means (not shown). That is, the end reference guide 15a and the like move according to the size of the sheet to be conveyed, and one end of the sheet is positioned at a predetermined position.

Next, the leading edge detecting means 16 comprises a detection flag 16a arranged on the downstream side of the lateral registration adjusting means 15 in the sheet conveying direction, and a photo sensor 16b for detecting the position of the flag 16a. That is, normally, the detection flag 16a is positioned between the light emitting element and the light receiving element of the photo sensor 16b, but when the recording sheet 3 is fed from the lateral registration adjusting means 15, the detection flag 16a is pushed up by the leading end thereof. This is detected by the photo sensor 16b, and the passage of the leading edge of the sheet is detected.

The first conveying roller pair 17 for conveying the recording sheet 3 with the leading edge detecting means 16 comprises a driving roller 17a and a roller 17b in pressure contact with the driving roller 17a. The roller pair 17 conveys the recording sheet 3 to be conveyed. It is arranged at a position biased to one side in the direction (sheet width direction) orthogonal to the direction. On the other hand, the second conveying roller pair 18 is composed of two driving rollers 18a and rollers 18b in pressure contact with the two driving rollers 18a, respectively, and is configured to nip and convey the recording sheet 3 in a laterally symmetrical position with respect to the center in the width direction. ing.

Incidentally, drive transmission gears 19a, 19b are provided at the ends of the roller shafts 17a1, 18a1 supporting the drive rollers 17a, 18a.
Are fixed, and both gears 19a and 19b are idler gears 19
They are meshed via c, and the driving force is transmitted from the same driving source to rotate.

The recording sheet 3 conveyed by the first conveying roller pair 17 and the second conveying roller pair 18 is a front guide member which also serves as a holder for supporting the lower guide member 20, the R path guide members 21a and 21b, and the roller 18b. It is guided by 22, conveyed by bending (U-turn), and retransmitted to the image forming unit.

In the structure of the above-described sheet conveying device, when the reversing sensor 11 detects the trailing edge of the recording sheet 3 sent to the reversing path 10 in the case of double-sided recording as described above, the reversing roller 12 rotates in the reverse direction to perform recording. The sheet 3 is guided to the resending path 13. At this point or before that, the lateral registration adjusting means 15 moves in the width direction of the recording sheet 3 by a signal from a control unit (not shown), and the size of the recording sheet 3 conveyed. Wait slightly outside the end position according to.

Next, the recording sheet 3 is fed to the skew feed roller pair 15b, 15
c, 15d, 15e, and one side end is fed to the end reference guide 15
The recording sheet 3 is conveyed in a state where it is abutted against a and the position of the one side edge is adjusted, and the rotation of the roller system is stopped when the leading edge detection means 16 detects the leading edge of the sheet. Then, the lateral registration adjusting means 15 is moved and positioned so that one end of the recording sheet 3 is accurately located at a predetermined position by the end reference guide 15a. The positioning position at this time is a side edge position corresponding to the sheet size when the recording sheet 3 is conveyed with the center as a reference. Therefore, as shown in FIG.
The position of the end reference guide 15a differs depending on the sheet sizes A, B, and C.

After that, all the rollers are rotated in response to a signal from the control unit to move the recording sheet 3 to the R path guide member 21a,
21b and the front guide member 22 guide and make U-turn conveyance, and send it into the image forming apparatus. Then, after the image is formed on the back surface in the image forming section, the sheet is guided by the flapper 9 and discharged to the discharging section 8.

By transporting the recording sheet 3 as described above, even in the case of double-sided transport, the lateral registration adjusting means enables center-based transport corresponding to a wide range of sheet sizes such as A3 size to A5 size. Problems such as temperature rise on the non-reference side of the fixing unit and uneven distribution of toner in the toner cartridge can be solved.

Further, even for a recording sheet such as A3 size, which is difficult to convey straight by only one side reference, the second conveying roller pair conveys by a plurality of rollers of center reference, so that low-cost plane conveyance and performance are possible. Gradient transportation, which is important, can be used together, reducing total cost.

Further, by aligning one side edge of the recording sheet 3 by the lateral registration adjusting means, it is possible to deal with the variation of the position of the sheet to be conveyed widely and flexibly, and in combination with the use of the first conveying roller pair 17, The sheet can be conveyed with high accuracy.

In the first embodiment, the R path guide member
Although the recording sheet 3 is bent and guided by 21a, 21b and the like, the same effect can be obtained even when the sheet 3 is linearly conveyed.

[Second Embodiment] In the first embodiment described above,
The example in which the first conveying roller pair 17 is arranged at a position deviated to one side in the width direction of the recording sheet 3 for conveying is shown, but as shown in FIG. Laura pair
Similar to 18, the driving rollers 17a and the rollers 17b are in contact with the driving rollers 17a, respectively, and may be nipped and conveyed at symmetrical positions with respect to the center reference of the width direction of the recording sheet 3.

With this configuration, the recording sheet 3
Even when the sheet is conveyed at a high speed or when a thick recording sheet is conveyed, since the roller arrangement of the first conveying means 17 is well balanced, the sheet can be stably conveyed, and the sheet can be conveyed with higher accuracy. Become.

[Third Embodiment] In the first embodiment described above,
The first conveying roller pair 17 is arranged at a position deviated to one side in the width direction of the recording sheet 3 which is conveyed. At this time, as shown in FIG. 5, the first conveying roller pair 17 in the width direction of the recording sheet 3 is arranged. A convex portion 20a may be formed on the lower guide member 20 that guides the conveyance lower surface of the recording sheet 3 on the side without the protrusion. The sheet guide surface of the convex portion 20a is arranged at substantially the same position as the nip portion of the first conveying roller pair 17 (a position slightly lower than the nip portion in this embodiment).

With the above-described structure, when the sheet conveyance accuracy required is lower than that of the second embodiment, the sheet conveyance becomes unstable due to the sheet path difference in the sheet width direction. , It is possible to easily reduce the difference in passage length. Therefore, it is possible to prevent the skew of the sheet without increasing the cost.

[0032]

Since the present invention is configured as described above, the lateral reference adjusting means for guiding the one side edge of the sheet makes it possible to carry the sheet with a center reference corresponding to a wide range of sheet sizes.

Further, the roller pair is arranged at a position deviated to one side in the width direction of the conveyed sheet, and the guide member is substantially the same as the nip portion of the roller pair on the side without the roller pair. If the lower surface of the sheet is guided so as to be positioned, the sheet can be accurately conveyed at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory diagram of an image forming apparatus using a sheet conveying apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration explanatory diagram of a sheet conveying device.

FIG. 3 is an explanatory view of a state in which sheets of different sizes are guided by a lateral registration adjusting unit.

FIG. 4 is a schematic configuration explanatory diagram of a sheet conveying device according to a second embodiment.

FIG. 5 is a schematic configuration explanatory diagram of a sheet conveying device according to a third embodiment.

FIG. 6 is an explanatory diagram according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical system, 2 ... Cassette, 2a ... Separation nail, 3 ... Recording sheet, 4a-4e ... Roller, 5 ... Photosensitive drum, 6 ... Transfer roller, 7 ... Fixing means, 8 ... Ejection part, 9 ... Flapper,
10 ... Inversion path, 11 ... Inversion sensor, 12 ... Inversion roller, 13 ...
Resending path, 14 ... Conveying roller pair, 15 ... Horizontal registration adjusting means, 15a ... End reference guide, 15b1 to 15b3 ... Oblique feeding roller,
15c1 to 15c3 ... Rollers, 15f ... Leaf spring, 15g1 to 15g3 ... Drive transmission member, 15h ... Belt, 15i ... Drive gear, 15j ... Drive shaft, 16 ... Tip detection means, 16a ... Detection flag, 16b ... Photo sensor, 17 ... first transport roller pair, 17a ... drive roller,
17b ... Roller, 18 ... Second conveying roller pair, 18a ... Driving roller, 18b ... Roller, 19a to 19c ... Gear, 20 ... Lower guide member, 21a, 21b ... R path guide member, 22 ... Front guide member

Claims (4)

[Claims] 1. A sheet conveying apparatus for conveying a sheet with a center position of the sheet as a reference, wherein an end reference guide for guiding one end of the sheet and one end of the sheet contacting the end reference guide. And a skew feed roller for transporting the sheets so that they come into contact with each other,
A lateral registration adjustment unit that is movable in a direction orthogonal to the sheet conveyance direction, a leading edge detection unit that detects the leading edge of the sheet that is positioned and conveyed by the lateral registration adjustment unit, and a sheet that is detected by the leading edge detection unit. A sheet transporting device comprising: a transporting unit for transporting; and a guide member for guiding a sheet transported by the transporting unit. 2. The conveying means is configured by disposing a roller pair at a position deviated to one side in a direction orthogonal to a conveying direction of a sheet to be conveyed, and the guide member is provided on a side where the roller pair is not provided. The sheet conveying apparatus according to claim 1, wherein the sheet conveying device is arranged so as to guide the lower surface of the sheet so as to be located at substantially the same position as the nip portion of the roller pair. 3. The sheet conveying apparatus according to claim 1, wherein the guide member bends and guides the sheet. 4. An image forming apparatus that conveys a sheet to form an image, wherein the sheet conveying apparatus according to any one of claims 1 to 3, and an image formed on the sheet conveyed by the sheet conveying apparatus. An image forming apparatus comprising: an image forming unit for forming an image.