JP3327735B2 - Sheet conveying device and image forming device - Google Patents

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 for a double-sided printing device and a duplicate printing device, 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 predetermined standard so that the sheet is conveyed to a predetermined image forming position. This standard includes a center standard and a one-side standard. The center reference is to convey the sheet so that the center in the width direction of the sheet is always at a fixed reference position, and the one-side reference is to convey the sheet so that one end in the width direction of the sheet abuts against the guide member, and the one end is The sheet is transported so as to be at a fixed reference position.

In the one-side reference, for example, as shown in FIG. 6, a skew feeding roller 51 is provided near an abutment reference member 50, a sheet 52 is conveyed by the skew feeding roller 51, and one end thereof is abutted. The sheet position is set by abutting against the reference member 50. This one-sided reference has an advantage that it can be easily provided at a low cost.

[0004]

However, in the above-described one-side reference configuration, as shown in FIG.
Depending on the sizes of B and C, the sheet conveyance position is deviated. When a small-sized sheet is conveyed on one side reference corresponding to a large sheet size, the other side is largely empty. For this reason, in an image forming apparatus or the like, the temperature rise on the non-reference side of the fixing device, and in an image forming apparatus using a toner cartridge, the toner in the cartridge tends to be biased.

When a large-size sheet is conveyed on one side, the sheet cannot be hit against the reference member when the sheet is bent and conveyed, for example, when the sheet is conveyed in a U-turn.
There is a risk of skewing and the like.

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

[0007]

In order to achieve the above object, a typical configuration according to the present invention includes an end reference guide for guiding one side end of a sheet, and a sheet provided on the end reference guide. And a pair of skew feeding rollers for pinching and conveying the sheet so that one side of the sheet abuts on the sheet, and the end reference guide and the pair of skew feeding rollers are orthogonal to the sheet conveyance direction. A lateral registration adjusting means movable in a direction, a conveying means for conveying the sheet sent from the lateral registration adjusting means, and a guide means for guiding the sheet conveyed by the conveying means, The adjusting means adjusts the end of the sheet so that the side end of the sheet is positioned at a positioning position corresponding to the sheet size after the one side end of the sheet is brought into contact with the end reference guide by the skew feeding roller pair. Standard And wherein the moving the oblique feed roller pair in a state of sandwiching the id and the sheet in the direction perpendicular to the conveyance direction of the sheet.

[0008]

In the above construction, the lateral registration adjusting means is moved to the side end position of the sheet corresponding to the center reference with respect to the sheet to be conveyed, so that the center reference sheet is conveyed by the one-side reference construction. Will be Then, the sheet is fed by the subsequent conveying means without skew even in the bent conveying path.

[0009]

【Example】

[First Embodiment] Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic structural explanatory view of an image forming apparatus using a sheet conveying device, FIG. 2 is a schematic structural 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 the description, first, the overall configuration of the image forming apparatus using the sheet transport device will be described, and then the configuration of the sheet transport device for re-sending the sheet will be described.

<< Overall Configuration of Image Forming Apparatus >> As shown in FIG. 1, this image forming apparatus irradiates information light based on image information from an optical system 1 to a drum-shaped electrophotographic photosensitive member, and A latent image is formed on the surface, 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 leading end of the cassette 2, and this is fed to a pair of transport rollers 4b. The toner image formed on the photosensitive drum 5 as the process cartridge is transferred to the image forming unit by the registration roller pair 4c and the like, and a voltage is applied to the transfer roller 6 as transfer means. Is transferred to 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. In the case of single-sided recording, the recording medium 3 is discharged to a discharge section 8 by discharge roller pairs 4d and 4e.

The recording sheet 3 is set on the basis of the center when the recording sheet 3 is fed from the cassette 2, and an 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 end of the recording sheet 3, the reversing roller 12 rotates and sends the recording sheet 3 to 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 to resend the image with the image recording surface of the recording sheet 3 up. Send it to Route 13.

The recording sheet 3 sent to the re-sending path 13 is conveyed by a pair of conveying rollers 14 and has a horizontal registration adjusting means 15.
When the leading end of the sheet is detected by the leading end detecting means 16, the sheet is conveyed by the first conveying roller pair 17 and the second conveying roller pair 18 and conveyed again to the image forming section, and the sheet is conveyed again. An image is formed on the back surface and discharged to the discharge unit 8.

{Sheet Conveying Apparatus} Next, the structure of a sheet conveying apparatus for resending the recording sheet 3 will be described.
This sheet conveying device is provided with the horizontal registration adjusting means 1 described above.
5. Tip detecting means 16, first and second transport 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 end in the width direction of the recording sheet 3 conveyed on the lower guide member 20.
The oblique feed rollers 15b1, 15b2, and 15b3 are provided near the guide 15a (the roller 15b in FIG. 2).
2, 15b3 only). Each of these oblique feed roller 15b1~15b3 roller 15c1,15c2,15c3 constitute a pressure to the pair of inclined feeding rollers by the leaf spring 15f. In addition, the oblique feed rollers 15b1 to 15b3 have drive transmission members 15g1, 15g2, 15g, respectively.
g3 is fixed, and the members 15g1, 15g2, and 15g3 are connected by a belt 15h. A drive gear 15i is connected to one drive transmission member 15g3 so as to transmit a driving force from a motor (not shown) to each of the oblique feed rollers 15b1 to 15b3.

Further, the drive gear 15i is slidably mounted on a drive shaft 15j having a D-cut shape, and the end reference guide 15a and a pair of oblique feed rollers 15b1 to 15b3, 15c1 to 15c1.
Reference numeral 15c3 is slidable by a moving means (not shown) in a direction perpendicular to the conveying direction of the recording sheet 3 (the direction of arrow a in FIG. 2). That is, the end reference guides 15a and the like move according to the size of the sheet to be conveyed, and position one end of the sheet at a predetermined position.

Next, the leading edge detecting means 16 comprises a detecting flag 16a disposed downstream of the horizontal 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 located between the light emitting element and the light receiving element of the photo sensor 16b, but when the recording sheet 3 is sent from the horizontal registration adjusting means 15, the detection flag 16a is pushed up by the leading end. 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 which conveys the recording sheet 3 detected by the leading end detecting means 16 is composed of a driving roller 17a and a roller 17b pressed against the driving roller 17a, and the roller pair 17 conveys the recording sheet 3 to be conveyed. It is arranged at a position deviated to one side in a direction (sheet width direction) orthogonal to the direction. On the other hand, the second transport roller pair 18 is composed of two drive rollers 18a and rollers 18b pressed against the drive rollers 18a, and is configured to nip and transport the recording sheet 3 at symmetrical positions with respect to the center in the width direction of the recording sheet 3. ing.

The drive transmission gears 19a, 19b are provided at the ends of the roller shafts 17a1, 18a1 for supporting the drive rollers 17a, 18a.
Are fixed, and both gears 19a and 19b are idler gears 19.
, and rotate by transmitting a driving force from the same driving source.

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. The sheet is guided by the sheet 22, conveyed in a bent (U-turn) manner, and sent again to the image forming section.

In the configuration of the sheet conveying apparatus, as described above, when the reversing sensor 11 detects the rear end of the recording sheet 3 fed to the reversing path 10 in the case of double-sided recording, the reversing roller 12 rotates in the reverse direction to perform recording. The sheet 3 is guided to the re-sending path 13. At this time or before that, the horizontal registration adjusting means 15 moves in the width direction of the recording sheet 3 according to a signal from a control unit (not shown), and the size of the recording sheet 3 conveyed. Waits slightly outside the end position corresponding to.

Next, the recording sheet 3 is fed to the pair of skew feeding rollers 15b and 15b.
c, 15d, and 15e, and convey one end to the end reference guide 15
Then, the recording sheet 3 is conveyed in a state where the position of the one side end is adjusted, and the rotation of the roller system is stopped when the leading end detecting means 16 detects the leading end 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 positioned at a predetermined position by the end reference guide 15a. The positioning position at this time is a side end position according to the sheet size when the recording sheet 3 is conveyed on the basis of the center. Therefore, as shown in FIG.
The position of the end reference guide 15a differs depending on the sheet sizes A, B, and C.

Thereafter, all the rollers are rotated by a signal from the control unit, and the recording sheet 3 is moved to the R path guide member 21a,
The sheet is conveyed by a U-turn while being guided by the front guide member 21b and the front guide member 22, and sent into the image forming apparatus. Then, after an image is formed on the back surface by the image forming unit, the image is guided by the flapper 9 and discharged to the discharge unit 8.

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

Further, even for a recording sheet which is difficult to convey straight by only one side reference such as A3 size, the second conveyance roller pair is conveyed by a plurality of rollers of center reference, so that low cost flat conveyance and performance can be achieved. The emphasis on gradient transport can be used together, reducing total cost.

Further, by aligning one end of the recording sheet 3 with the lateral registration adjusting means, it is possible to respond to 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, This enables highly accurate sheet conveyance.

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

[Second Embodiment] In the first embodiment described above,
The example in which the first conveying roller pair 17 is disposed at a position deviated to one side in the width direction of the recording sheet 3 that conveys the first conveying roller pair 17 is shown in FIG. Roller pair
As in the case of 18, the recording sheet 3 may be constituted by two driving rollers 17a and rollers 17b pressed against the rollers, and may be configured to be nip-conveyed at a symmetrical position relative to the center of the recording sheet 3 in the width direction.

With this configuration, the recording sheet 3
Even when the sheet is conveyed at high speed or when a thick recording sheet is conveyed, the roller arrangement of the first conveying means 17 is well-balanced, so that the sheet can be stably conveyed and more accurate sheet conveyance is possible. Become.

[Third Embodiment] In the first embodiment described above,
The first conveying roller pair 17 is disposed at a position deviated to one side in the width direction of the recording sheet 3 to be conveyed. At this time, as shown in FIG. On the side where no recording sheet 3 is provided, a projection 20a may be formed on the lower guide member 20 that guides the lower surface of the recording sheet 3 being conveyed. The sheet guide surface of the convex portion 20a is configured to be substantially at the same position as the nip portion of the first conveying roller pair 17 (in this embodiment, a position slightly lower than the nip portion).

With the above construction, when the required sheet conveyance accuracy is lower than that of the second embodiment, when the sheet conveyance becomes unstable due to a difference in the sheet path in the width direction of the sheet. The difference in passage length can be reduced simply. Therefore, skewing of the sheet can be prevented without increasing the cost.

[0032]

Since the present invention is constructed as described above, it is possible to convey a sheet based on a wide range of sheet sizes by means of a lateral registration adjusting means for guiding one side edge of the sheet.

Further, a roller pair is disposed 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 configured to be guided to the position, the sheet can be accurately conveyed at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view of an image forming apparatus using a sheet conveying device according to one embodiment of the present invention.

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

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

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

FIG. 5 is a schematic configuration explanatory view of a sheet conveying apparatus 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 claw, 3 ... Recording sheet, 4a-4e ... Roller, 5 ... Photoconductor drum, 6 ... Transfer roller, 7 ... Fixing means, 8 ... Discharge part, 9 ... Flapper,
10 ... reversing path, 11 ... reversing sensor, 12 ... reversing roller, 13 ...
Retransmission path, 14: transport roller pair, 15: lateral registration adjustment means, 15a: end reference guide, 15b1 to 15b3: oblique roller,
15c1 to 15c3: Roller, 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 transport roller pair, 18a: drive roller, 18b: roller, 19a to 19c: gear, 20: lower guide member, 21a, 21b: R path guide member, 22: front guide member

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-192649 (JP, A) JP-A-4-371438 (JP, A) JP-A-5-35016 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B65H 9/00 B65H 7/08 B65H 7/14 B65H 15/00

Claims (5)

(57) [Claims] An end reference guide for guiding one end of the sheet; and an oblique feed roller for nipping and conveying the sheet so that one end of the sheet abuts on the end reference guide. A lateral registration adjusting means comprising a pair of the end reference guide and the skew feeding roller pair capable of moving the pair of skew feeding rollers in a direction orthogonal to a sheet conveying direction; and a conveyance for conveying the sheet sent from the horizontal registration adjusting means. Means, and guide means for guiding the sheet conveyed by the conveying means, wherein the lateral registration adjusting means has one side end of the sheet abutted on the end reference guide by the pair of skew feeding rollers. later, as the side edge of the sheet is positioned in the positioning position corresponding to the sheet size, the conveying direction and straight in the oblique feed roller pair in a state of sandwiching the end reference guide and sheet sheet Sheet conveying apparatus characterized by moving in the direction of exchange. 2. The transporting means comprises a roller pair disposed at a position deviated to one side in a direction orthogonal to a transport direction of a sheet to be transported, and the guide member is provided on a side where the roller pair is absent. 2. The sheet conveying device according to claim 1, wherein the sheet conveying device is arranged to guide the lower surface of the sheet so as to be substantially at the same position as the nip portion of the roller pair. 3. The sheet conveying apparatus according to claim 1, wherein the guide member guides the sheet by bending the sheet. 4. The apparatus according to claim 1, wherein said horizontal registration adjusting means is transported.
Wait slightly outside the edge position according to the size of the sheet
2. The sheet conveying device according to claim 1, wherein the sheet conveying device is operated.
Place . 5. An image forming apparatus for conveying a sheet to form an image, wherein the image is formed on a sheet conveyed by the sheet conveying apparatus according to any one of claims 1 to 4. An image forming apparatus, comprising: an image forming unit for forming.