JPH08169648A - Sheet ejection device and image forming apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the stackability of sheets on the intermediate tray. [Structure] On a sheet conveying path that is formed substantially linearly,
Upper and lower guide members 42A, 42B, 43A, 43B, 44A, 44B forming a part of the entire sheet conveying path,
Conveying roller pairs 45, 46, 47, 48 forming the first, second, third and fourth discharge ports a, b, c, d are arranged alternately. Then, the pair of transport rollers 46 and the upper and lower guide members 4
2A and 42B are integrally formed by the solenoid 61, the conveying roller pair 47 and the upper and lower guide members 43A and 43B are integrally formed by the solenoid 62, and the conveying roller pair 48 and the upper and lower guide members 44A and 44B are integrally formed by the solenoid 63. It was possible to evacuate from the transport path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly to a sheet discharging apparatus provided in an image forming apparatus capable of double-sided image formation and multiple image formation.

[0002]

2. Description of the Related Art In image forming apparatuses such as copiers, printers, and facsimiles, double-sided image formation is performed to form images on both front and back sides of a sheet, and image formation is performed multiple times on the same side of a sheet. There is one that enables multiple image formation to be performed. As described above, the image forming apparatus main body of the image forming apparatus capable of double-sided image formation and multiplex image formation is temporarily stacked with the image-formed sheets, and a predetermined number of sheets can be stacked. When finished, sheet stacking means (intermediate tray) for re-feeding stacked sheets one by one to the image forming unit is provided.

And, on the upper part of the sheet stacking means,
A sheet discharge device is provided for discharging the image-formed sheet, which has been subjected to image formation in the image forming section, onto the sheet stacking unit. Generally, this sheet ejection device
In order to discharge the sheets onto the sheet stacking means in accordance with the size (size in the conveying direction), a plurality of discharge ports are provided in the sheet conveying direction of the sheet conveying path formed in a substantially straight line. There is.

FIG. 3 shows the overall structure of a conventional image forming apparatus (copying machine) having the above-mentioned sheet discharging device and capable of double-sided image formation and multiple image formation.

The sheet S fed from the sheet feeding cassette 1 or 2 by the sheet feeding rollers 3 and 4 rotating in the clockwise direction has the uppermost sheet of 1 by the pair of separating rollers 5 and 6 for separating the sheets one by one. It is sent to the registration roller pair 7 which is separated into sheets and whose rotation is stopped.

Sheet S sent to registration roller pair 7
When the leading edge of the sheet hits the nip of the registration roller pair 7 and forms a predetermined loop, the conveyance is stopped. The skewed state of the sheet S is corrected by forming a loop.

The sheet S, whose skewed state has been corrected, is rotated by the registration roller pair 7 which starts rotation at the timing of aligning the position with the toner image on the photosensitive drum 8 rotating clockwise. 8 is sent to the transfer section between the transfer charger 9 and the transfer charger 9.

On the sheet surface of the sheet S sent to the transfer portion, the toner images on the photosensitive drum 8 rotating in the clockwise direction are sequentially transferred by the transfer charger 9. As a result, in the case of the double-sided image forming mode, the image formation on one side of the sheet is completed. In the case of the multiple image forming mode, the first image formation on the sheet surface is completed.

A toner image is formed on the photosensitive drum 8 as follows. The optical system 30 scans an image of a document (not shown) set on the document table 29. Optical system 30
The original image (light image) L scanned by is projected onto the photosensitive drum 8 rotating clockwise. As a result, an electrostatic latent image is formed on the photosensitive drum 8, and this electrostatic latent image becomes a visible image (toner image) by the toner supplied from the developing device 31.

The sheet S after the transfer of the toner image is sent to the fixing roller pair 11 by the conveying belt 10 and passes through the nip of the identification fixing roller pair 11 to be heated by the fixing roller 11A and pressure roller. The transfer toner image is fixed on the sheet surface by being pressed by 11B.

The sheet S on which the toner image fixing process has been completed is
In the single-sided image forming mode, the sheet is conveyed to the conveying roller pair 12, passes through the sheet discharge path 13, and is discharged onto the sheet discharge tray (not shown) outside the apparatus by the sheet discharge roller pair 14. At this time, the flapper 15 opens the paper discharge path 13.

In the double-sided image forming mode and the multiple image forming mode, the sheet is conveyed by the pair of conveying rollers 12 and 16 and passes through the vertical path 17 to the sheet discharging device 19 installed above the intermediate tray 18. Sent. At this time, the flapper 15 opens the vertical path 17.

The sheet S sent to the vertical path 17 is sent to the reverse path 21 by the pair of transport rollers 20 in the double-sided image forming mode. At this time, the flapper 22 is the reverse path 2
Open one. The sheet S sent to the reversing path 21 is switched back by the conveying roller pair 20 which reverses when the trailing end reaches the immediately upstream portion of the conveying roller pair 20, and the image forming surface is directed upward so that the sheet discharging device. Sent to 19.

In the case of the multiple image forming mode, the image forming surface is directed downward through the vertical path 17 and is sent to the sheet discharging device 19. At this time, the flapper 22 closes the reverse path 21.

The sheet discharging device 19 has a plurality of discharging ports a, b, c in the sheet conveying direction of the sheet conveying path 23 formed in a substantially straight line. The discharge ports a, b, and c are the nips of the pair of transport rollers 24, 25, and 26 that transport the sheet. Immediately downstream of the pair of transport rollers 24, 25, flappers 27, 2 for opening and closing the discharge ports a, b are provided.
8 are installed. The flappers 27 and 28 close the discharge ports a and b when they are in a horizontal position as shown in the figure, but open upward when the flappers 27 and 28 pivot upward about the support shafts 27a and 28a. .

In the present image forming apparatus, when a sheet S having a long size in the conveying direction (for example, A3 size vertical feed, B4 size vertical feed, etc.) is used, the sheet discharge device 19
Opens the uppermost discharge port a and discharges the long size sheet S onto the intermediate tray 18 from the discharge port a. In this case, the flapper 27 is rotated upward to take the ejection posture.

When a sheet S having a size shorter than that of the sheet S (for example, A4 size vertical feed, B5 size vertical feed, etc.) is used, the sheet discharge device 19 discharges the sheet downstream of the discharge port a. The outlet b is opened, and the medium size sheet S is discharged from the discharge port b onto the intermediate tray 18. In this case, the flapper 28 is rotated upward to take the ejection posture.

When a sheet S having a size shorter than that of the sheet S (for example, A4 size lateral feed, B5 size lateral feed, etc.) is used, the sheet ejection device 19 ejects the sheet downstream of the ejection port b. The short size sheet S is discharged onto the intermediate tray 18 from the outlet c.

The long sheet S discharged from the discharge port a is guided by the flapper 27 and lands on the intermediate tray 18 while flying in the air.

The medium-sized sheet S discharged from the discharge port b is guided by the flapper 28 and lands on the intermediate tray 18 while flying in the air.

The short sheet S discharged from the discharge port c lands on the intermediate tray 18 while flying in the air.

Discharge ports a, b, c are provided on the intermediate tray 18.
A width-direction restricting portion 32 that restricts the width-direction position of the sheet S discharged from the vehicle and landing while flying in the air, and a leading-edge restricting portion 33 that restricts the leading-edge position are provided.

The sheet S discharged from the discharge ports a, b, and c and landed on the intermediate tray 18 is fed by a sponge feeding roller 34 rotating counterclockwise, and the leading end of the sheet is re-fed roller 35A. And separation roller 35
It is sent to the nip of the separation roller pair 35 composed of B and B. Then, the sheets S fed into the nip of the separation roller pair 35 are separated one by one, and are again fed to the registration roller pair 7 by the conveyance roller pair 36.

[0024]

However, the conventional image forming apparatus having the sheet discharging device 19 has the following problems.

That is, the sheet S sent to the sheet ejecting device 19 after the image formation is once completed is usually provided with a curl attached in the process of passing through the fixing roller pair 11, for example. . When the sheet S after the transfer of the toner image passes the fixing roller pair 11, the fixing roller 11
The toner shrinks because it is heated by A, and the sheet S
I get curls.

Generally, the sheet S in the double-sided image forming mode is stacked on the intermediate tray 18 with the image forming surface facing upward.
4 is sent to the sheet discharging device 19, FIG.
As shown in (a), when the sheet S in the multiple image forming mode, which has an upward curl and is stacked on the intermediate tray 18 with the image forming surface facing downward, is sent to the sheet discharging device 19, As shown in FIG. 4 (b), it often has a downward curl.

As described above, when the sheet S sent to the sheet discharging device 19 has an upward or downward curl, the sheet S discharged from the discharge ports a and b is flappered.
In the sheet discharge device 19 of the conventional example which guides downwards by 7, 28, as shown in FIGS. 4 (a) and 4 (b),
The leading edge Sa of the sheet S-2 discharged from the discharge ports a and b
Is the sheet S already loaded on the intermediate tray 18.
Since the sheet S-1 is loaded from the rear end Sb side of -1, the sheet may not be loaded on the intermediate tray 18.

That is, as shown in FIG. 4 (a), the sheet S-2 having an upward curl from the discharge ports a and b.
If the sheet is discharged, the curled sheet tip Sa
Is likely to hit the trailing edge Sb of the already stacked sheets S-1 with the upward curl and become unstackable.

Further, as shown in FIG. 4B, when the downward curled sheet S-2 is discharged from the discharge ports a and b, the curled sheet front end Sa is already loaded. The sheet S-1 is hit against the rear end Sb with the downward curl and is rolled,
Easy to be loaded.

In this way, on the intermediate tray 18,
If the sheets S are not stacked correctly, it is impossible to feed the sheets S to be re-fed from the intermediate tray 18 and the double feeding,
Problems such as skewing occur.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet discharging device capable of correctly stacking sheets on the sheet stacking means.

[0032]

The present invention has a plurality of discharge ports (a, b, c) in the sheet conveying direction of the entire sheet conveying path (41) formed in a substantially straight line, The present invention relates to a sheet discharging device that discharges a sheet (S) by selecting a discharging port according to the sheet size from the discharging ports (a, b, c).

In the present invention, in order to achieve the above object, the conveying path forming means (42A, 42B, 43A, 43B, 44) forming a part of the entire sheet conveying path (41).
A, 44B) and a plurality of sheet conveying means (45, 46, 47, 48) forming one discharge opening (a, b, c, d) are arranged in the sheet conveying direction, and each pair of Conveyance path forming means (42A, 42B, 43A, 43B, 44
A, 44B) and the sheet conveying means (45, 46, 4)
7, 48) can be integrally withdrawn from the sheet conveying path (41) by using the withdrawing means (61, 62, 63), and is located downstream of the discharge port selected according to the sheet size. All of the conveying path forming means and the sheet conveying means are retracted from the sheet conveying path (41) by using the retracting means (61, 62, 63).

[0034]

According to the sheet discharging apparatus of the present invention having the above structure, when the discharging port (a, b, c, d) corresponding to the sheet size is selected, the discharging port (a, b, c, d) is selected. All the transport path forming means (42A, 42B,
43A, 43B, 44A, 44B) and the sheet conveying means (45, 46, 47, 48) are retracted from the sheet conveying path (41). Therefore, the outlets (a, b,
The leading edge of the sheet (S) discharged from c, d) fly in the air as far as possible downstream and land on the sheet stacking means (18).

As a result, the sheets (S) discharged from the discharge ports (a, b, c, d) fall from above the sheets (S) already stacked on the sheet stacking means (18). As the sheets are stacked, the sheets (S) discharged from the discharge ports (a, b, c, d) and the sheets (S) stacked on the sheet stacking unit (18) have an upward or downward curl. However, the sheets (S) can be stacked well.

The reference numerals in parentheses refer to the drawings and do not limit the structure of the present invention.

[0037]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of the sheet discharging device and the intermediate tray of the present invention, and FIG. 2 shows the detailed structure of the sheet discharging device of the present invention.

The sheet discharging device 40 is applied to an image forming apparatus having the same structure as the above-mentioned conventional image forming apparatus. Therefore, the same members and the like will be described with the same reference numerals.

The sheet discharging device 40 has a sheet conveying path 41 formed in a substantially linear shape. In the sheet conveyance direction on the sheet conveyance path 41, the sheet conveyance path 41
A plurality of sets of upper and lower guide members 42 forming a part of the whole
A, 42B, 43A, 43B, 44A, 44B and a plurality of conveying roller pairs 45, 46, 47, 48 are alternately arranged.

In the present sheet discharging device 40, the nip of the most upstream conveying roller pair 45 forms the first discharging port a for discharging the sheet S having the maximum size (size in the conveying direction), and the downstream of the first discharging port a. The nip of the transport roller pair 46 forms the second discharge port b for discharging the sheet S of a shorter size, and the nip of the transport roller pair 47 on the downstream side discharges the sheet S of a shorter size. The third discharge port c is formed, and the nip of the most downstream conveyance roller pair 48 forms the fourth discharge port d for discharging the sheet S having the minimum size.

The most upstream conveying roller pair 45 is fixed at a predetermined position, but the other conveying roller pairs 46, 4 are provided.
The sheets 7 and 48 can be retracted from the sheet conveying path 41. Therefore, the pair of transport rollers 46, 47, 48 are attached to support members 52, 53, 54 which are rotatable in the up and down directions about the support shafts 49, 50, 51.

The upper and lower guide members 42A, 42B, 43A,
43B, 44A, and 44B can also be retracted from the sheet conveyance path 41. In this case, the upper and lower guide members 42A,
42B is retracted integrally with the transport roller pair 46, upper and lower guide members 43A and 43B are retracted integrally with the transport roller pair 47, and upper and lower guide members 44A and 44B are transported roller pair 4.
Evacuate together with 8.

The upper and lower guide members 42A, 42B, 43A,
Each of the downstream ends of 43B, 44A, and 44B has a support member 5
2, 53 and 54 are rotatably coupled to each other, and the upstream ends of the respective lower guide members 42B, 43B and 44B are oblong guides that are obliquely formed in the image forming apparatus main body (not shown). It is slidably coupled to the grooves 55, 56, 57. The upstream side ends of the upper guide members 42A, 43A, 44A are fixed to the lower guide members 42B, 43B, 44B via spacers 58, 59, 60.

One end of each support member 52, 53, 54 is rotatably connected to an electromagnetic solenoid (retraction means) 61, 62, 63.

When the electromagnetic solenoid 61 is turned on, FIG.
In FIG. 5, the pair of conveying rollers 46 and the upper and lower guide members 42A and 42B located at the position (sheet conveying position) shown by the solid line are retracted from the sheet conveying path 41 to the position shown by the dotted line. As a result, the first outlet a opens.

Similarly, when the electromagnetic solenoid 62 is turned on, the conveying roller pair 47 and the upper and lower guide members 43A and 43B located at the positions shown by the solid lines are retracted from the sheet conveying path 41 to the positions shown by the dotted lines. As a result, the second outlet b is opened.

Similarly, when the electromagnetic solenoid 63 is turned on, the conveying roller pair 47 and the upper and lower guide members 44A and 44B located at the positions shown by the solid lines are retracted from the sheet conveying path 41 to the positions shown by the dotted lines. As a result, the third outlet c is opened.

When the sheet S is discharged from the first discharge port a of the sheet discharge device 40, all the electromagnetic solenoids 61, 62 and 63 are turned on to convey the sheet downstream of the first discharge port a. Roller pairs 46, 47, 48 and upper and lower guide members 42A, 42B, 43A, 43B, 44A, 44B
Is retracted from the sheet conveyance path 41.

When the sheet S is discharged from the second discharge port b, the electromagnetic solenoids 62 and 63 are turned on so that the pair of conveying rollers 47 and 4 downstream of the second discharge port b.
8 and upper and lower guide members 43A, 43B, 44A, 44B
Is retracted from the sheet conveyance path 41.

When the sheet S is discharged from the third discharge port c, the electromagnetic solenoid 63 is turned on and the third
The conveying roller pair 48 and the upper and lower guide members 44A and 44B downstream of the sheet discharge port c are retracted from the sheet conveying path 41.

When the sheet S is discharged from the fourth discharge port d, all the electromagnetic solenoids 61, 62, 6
3 is turned off, and the conveying roller pairs 46, 47, 48 and the upper and lower guide members 42A, 42B, 43A, 43B, 44
A and 44B are placed on the sheet conveyance path 41 to be in the conveyance posture.

The above-described selection of the discharge ports a, b, c, d is executed by pressing the discharge port selection key 64 provided on the operation unit (not shown) of the image forming apparatus main body. Outlet selection key 6
When the signal from 4 is input, the CPU 65, which controls the overall operation of the image forming apparatus, controls the electromagnetic solenoids 61, 62, 63 so that the selected discharge port is opened.

[0054]

As described above, in the sheet discharging apparatus of the present invention, the sheets discharged from the plurality of discharging ports provided in the sheet conveying direction of the sheet conveying path formed in a substantially straight line are provided. Since the front end is made to be able to move downstream while flying in the air, the sheets discharged from the respective discharge ports fall from above the sheets already stacked on the sheet stacking means and are stacked.

Therefore, even when a sheet having an upward or downward curl is discharged, the discharged sheet can be correctly stacked on the sheet stacking means.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing an overall configuration of a sheet discharging device and an intermediate tray according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing a detailed configuration of the sheet ejection device.

FIG. 3 is a vertical cross-sectional side view showing the overall configuration of a conventional image forming apparatus (copying machine).

FIG. 4 is a vertical cross-sectional side view illustrating a problem that occurs in the sheet discharging device of the image forming apparatus.

[Explanation of symbols]

8 Photosensitive Drum (Image Forming Means) 18 Intermediate Tray (Sheet Stacking Means) 41 Sheet Conveying Path 42A, 42B, 43A, 43B, 44A, 44B
Guide member (conveying path forming means) 45, 46, 47, 48 Conveying roller pair (sheet conveying means) 61, 62, 63 Electromagnetic solenoid (retracting means) a, b, c, d Discharge port S sheet

Claims (6)

[Claims] 1. A sheet having a plurality of discharge ports in a sheet transport direction on a sheet transport path that is formed in a substantially linear shape, and selects a discharge port corresponding to a sheet size from among these discharge ports. In a sheet discharging apparatus for discharging sheets, a plurality of pairs of conveying path forming means forming a part of the entire sheet conveying path and sheet conveying means forming one discharge port are arranged in the sheet conveying direction, and each pair of the conveying means is arranged. The path forming means and the sheet conveying means can be integrally retracted from the sheet conveying path by using the retracting means, and all the conveying path forming means positioned downstream of the discharge port selected according to the sheet size. A sheet discharging device, wherein the sheet conveying means and the sheet conveying means are retracted from the sheet conveying path by using the retracting means. 2. The sheet discharging apparatus according to claim 1, wherein the conveying path forming unit is composed of upper and lower guide members that guide the upper surface side and the lower surface side of the sheet. 3. The sheet discharging device according to claim 1, wherein a pair of conveying rollers is used for the sheet conveying means. 4. The sheet ejection device according to claim 1, wherein an electromagnetic solenoid is used for the retracting means. 5. A discharge port selection means for selecting a discharge port according to a sheet size, and the transport path forming means and the sheet transport means downstream of the discharge port selected by the discharge port selection means are retracted. The sheet ejection device according to claim 1, further comprising: a control unit that drives and controls the retracting unit. 6. The sheet discharging device according to claim 1, sheet stacking means for temporarily stacking and re-feeding sheets discharged from the sheet discharging device, and sheet feeding. And an image forming unit for forming an image on the formed sheet.