JP3179944B2 - Structure of the paper output section - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a mechanism for discharging a recording sheet on which an image has been recorded in an image forming section of an image forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine, a printer, and a facsimile apparatus has a structure for discharging a recording sheet on which an image has been formed onto a discharge tray. The recording paper is discharged onto the paper discharge tray while being nipped by the disposed paper discharge roller pair. The paper discharging roller is configured to stiffen the recording paper at the time of nip to prevent the discharged recording paper from being curled. Here, stiffening means that one or both diameters of the discharge rollers are made different in the axial direction, thereby intentionally forming a curl in a direction perpendicular to the transport direction when the paper is passed. Means to prevent.

However, when a thick paper (for example, 135k paper) is discharged and nipped by the above-described discharge roller pair and crimped, abnormalities such as streak-like lines are formed on the image, It causes image quality to deteriorate.
In view of such circumstances, there has been a demand for the development of an apparatus that can always provide a proper waist and realize a curl-free discharge regardless of the difference in paper type such as paper thickness and material. In addition,
A technique in which the discharge roller pressure can be adjusted to change the discharge direction (Japanese Utility Model Application Laid-Open No. 64-59246), or a configuration in which the nip between the discharge rollers is released by opening a cover (Japanese Patent Laid-Open No. 63-192072). However, none of these methods solves the above-mentioned problem corresponding to the change in the paper thickness, and is merely intended to change the transport direction or to clear the jam. However, the above-mentioned problem cannot be solved even if the method is applied.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is possible to always provide a proper waist and to realize a good discharge without curling regardless of the difference in paper type such as paper thickness and material. It is an object of the present invention to provide a structure of a recording paper discharge section as described above.

[0005]

In order to achieve the above object, the present invention relates to an image forming apparatus provided with a pair of upper and lower discharge rollers at a discharge port, wherein one of the discharge rollers is moved in the up and down direction to form a double discharge. An image forming apparatus having a configuration in which the distance between the rollers can be adjusted, a pair of upper and lower discharge rollers at a discharge port, and a fixing device upstream of the pair of discharge rollers is provided. An upper and lower discharge guide plate sandwiching a discharge path between the pair of discharge rollers, a means for adsorbing recording paper on one of the upper and lower discharge guide plates, and a transport belt; The image forming apparatus includes a means for adsorbing the recording sheet only when the conveyance force of the discharge roller pair falls below a predetermined value and a control unit for operating the conveyance belt. Discharge roller trace elimination mode on the operation panel When the control unit is turned on, the control unit shifts to a discharge roller trace elimination mode to increase the interval between the discharge rollers. When a sorter is connected to the discharge port, the control unit causes the pair of discharge rollers to move. Always open,
In an image forming apparatus having a pair of upper and lower discharge rollers at a discharge port and a fixing device upstream of the pair of discharge rollers, a discharge path between the fixing device and the pair of discharge rollers is sandwiched. The upper and lower discharge guide plates are provided so that each discharge roller is concealed by the discharge guide plate when the pair of discharge rollers is completely opened. In an image forming apparatus including a paper discharge roller and a fixing device upstream of the paper discharge roller pair, an upper and lower paper discharge guide plate sandwiching a paper discharge path between the fixing device and the paper discharge roller pair And a guide rib for guiding the recording sheet to a gap between the pair of paper discharge rollers when the pair of paper discharge rollers is completely opened.

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings. 1 (a) and 1 (b) are a front view and a partial side view, respectively, showing a main part of an embodiment of the present invention, and FIG. 2 is an operation explanatory diagram of FIG. The illustrated portion shows the configuration of a fixing device of an image forming apparatus using an electrophotographic process and a paper discharge mechanism located downstream of the fixing device. And the recording paper P on which the toner image has been transferred is
Then, the toner image is fixed by entering the nip portion of the pressure roller 3. A paper discharging mechanism 10 located downstream of the fixing device includes an upper paper discharging guide plate 11 and a lower paper discharging guide plate 12 for guiding the recording paper P discharged from the fixing device 1 to the downstream side.
The upper discharge guide plate 11 is supported rotatably in a vertical direction about a fulcrum 15, and the upper discharge roller 13 is driven by the upper discharge roller 13 and the lower discharge roller 14 on the driving side. The upper discharge roller 13 is rotatably supported at the tip of a holder 16 which is a leaf spring extending from the paper guide plate 11. As means for vertically moving the upper guide plate 11 and the like, FIG.
A solenoid 17 as shown in FIG.
, The upper guide plate 11 is constantly urged downward, while being pulled up by the operation of the solenoid 17. By adjusting the projecting length of the plunger of the solenoid, it is possible to adjust the interval between the discharge rollers. The paper discharge roller pair has a configuration for giving a stiffness to the recording paper. Reference numeral 19 denotes a discharge tray, and reference numeral 20 denotes a discharge cover. Reference numeral 21 shown in FIG. 2 is a separation claw.

FIG. 3 is a schematic view showing another means for vertically moving the upper discharge guide plate. A cam 25 is arranged at a position facing a projection 11a provided at a proper lower portion of the upper guide plate 11. By rotating the cam automatically or manually, the cam 25 presses the protrusion 11a to raise it,
It is configured so that pressing can be released and lowered. 1 and 2, the upper discharge guide plate may be manually moved up and down. In this case, a part of a shaft member or the like protruding from the upper guide plate 11 is externally mounted on the apparatus. It may be configured so that it can be manipulated by projecting it to the.

According to the configuration of the above-described embodiment, since the paper discharge roller is provided so as to move up and down integrally with the guide plate, when the recording paper to be subjected to image formation is thick, the paper is discharged in advance as shown in FIG. By adjusting the distance between the paper rollers to a large value, it is possible to prevent the thick paper from being formed with streak-like lines by the paper discharge rollers, and to prevent deterioration in image quality. In the case of a recording paper of a normal paper type, the operation may be performed with the upper and lower discharge rollers nipped as shown in FIG.

FIG. 4 shows a modified embodiment in which the upper and lower guide plates 11 and 12 are fixed, while the holder 16 supporting the upper discharge roller 13 is pivotally movable up and down by other parts than the upper guide plate. It is characterized in that the holder is moved up and down by a solenoid 17. In this embodiment, the spacing can be adjusted according to the paper thickness by raising and lowering only the upper discharge guide plate alone, and the same effect as in the above embodiment can be obtained. By the way, in each of the above-described embodiments, since the discharge roller pair is provided with an interval or is completely opened, the recording paper that has passed through the fixing nip loses the conveying force and is not conveyed to the paper discharge tray. It is also conceivable that it remains in the machine body. For this purpose, it is one method to make the space between the fixing device and the paper discharge tray as close as possible, but it may be difficult in terms of layout.

FIGS. 5 to 7 show an embodiment for solving such a problem. A conveying belt and a recording paper suction fan are provided on one of upper and lower discharge guide plates.
The recording paper is transported to a discharge tray. That is, as shown in FIG. 5, the paper discharge mechanism 10 is configured such that the upper paper discharge guide plate 11 and the upper paper discharge roller 13 can be moved up and down, while the conveyance belt 30 and the suction belt are placed in the lower paper discharge guide plate 12. The configuration in which the fan 31 is arranged is characteristic. The specific configurations of the transport belt and the suction fan are as shown in the enlarged views of FIGS. 6 and 7. The upper surface of the lower discharge guide plate is partially open, and the transport belt 30 housed inside is lower. It is arranged to be able to move up and down relatively to the paper guide plate 12. Further, the ventilation pipe 33 is penetrated at a position avoiding the transport belt (a plurality of narrow belts are arranged in parallel at a predetermined interval), and the lower end of each ventilation pipe 33 is a tube 34.
Is connected to the fan body 35 arranged outside via the. The upper end of the ventilation pipe is opened at a position avoiding the belt 30, and faces the recording paper transport path. When the fan body 35 is driven to rotate, a negative pressure is generated in the ventilation pipe 33, and the recording paper that is going to pass above the lower discharge guide plate 12 can be sucked.

FIG. 7 shows an example of a configuration for moving the transport belt 30 up and down relatively to the paper discharge guide plate. In this example, the transport belt side is fixed, and the lower paper discharge guide plate 12 is moved by the solenoid 40. By raising and lowering, the transport surface of the transport belt can be exposed or retracted. That is, when the discharge roller pair maintains the conveyance force, the conveyance belt 30 is retracted into the lower discharge guide plate 12 as shown in FIG. 6, but the conveyance force is increased by opening the conveyance roller pair. If lost, solenoid 40
Is operated to lower the lower discharge guide plate 12 to expose the transport belt 30, and the recording paper is discharged to the discharge tray side in cooperation with the suction means. In the above embodiment, the guide plate is moved, but the conveyor belt may be moved up and down. The suction fan is shown in FIG.
May be provided inside the guide plate, or may be provided outside as shown in FIG. Further, a mechanism including a suction fan and a transport belt may be provided on the upper guide plate side. In FIG. 7, ventilation pipes and the like are omitted.

In this embodiment, when the suction fan and the conveyor belt are operated, for example, when the interval between the pair of conveying rollers is an interval that can sufficiently maintain the conveying force (for example, 10 gf or more), the operation is not performed. When the distance between the discharge roller pair is widened and the conveying force is lost (for example, 10 gf
The following only needs to be performed so as to operate. Next, in the above-described embodiment, since the operation of manually adjusting the interval between the paper discharge roller pairs and opening the paper discharge roller pair is complicated, the adjustment and release means using the solenoid and the like are provided by a key on an operation panel (not shown). Conveniently, the operation is started and released by an operation. In this case, a “paper discharge roller trace elimination mode” key is provided on the operation panel, and a program of the control unit is set so that the above operation can be realized by operating this key.

FIGS. 8 (a) and 8 (b) are a main flow chart showing a control procedure having the above-described discharge roller trace elimination mode and a subroutine flowchart showing a control procedure of the discharge roller trace elimination mode. When the copy start button is turned on when the trace elimination mode is selected, the solenoid 17 for adjusting the interval between the discharge rollers, the solenoid 40 for lowering the guide plate, the fans 31 and 35, and the transport belt 30 are sequentially or simultaneously turned on to discharge the paper. (Steps S1 to S
4). If the paper discharge sensor is turned on in step 5, the recording paper has been properly discharged onto the paper discharge tray.

Next, FIG. 9 shows an example in which a sorter 46 is arranged at the paper discharge port of the image forming apparatus main body 45, and introduction rollers 47 and 48 are arranged inside the introduction port of the sorter 46.
In this case, the pair of paper discharge rollers 13 and 1 on the image forming apparatus main body side are used.
4 and the introduction roller pair 47, 48 on the sorter side are in a state of being arranged close to each other, so that even if the discharge roller pair loses the conveying force, the leading end of the recording paper is kept in the introduction roller pair 4
When the recording paper reaches the nip portions 7 and 48, the recording paper is given a conveying force, and is conveyed into the sorter. However, in this case, the distance between the nip portion of the rollers 2 and 3 constituting the fixing device 1 and the nip portion of the pair of introduction rollers 47 and 48 needs to be shorter than the length of the recording paper in the transport direction. For example, when the A4 size recording paper is conveyed in the horizontal direction, the distance needs to be 200 mm or less.
According to this configuration, it is possible to prevent the formation of the discharge roller trace by always opening the discharge roller pair.

By the way, in the case where the roller interval is opened in order to eliminate the trail of the discharge roller, if the discharge roller having lost the conveying force protrudes above the paper passing surface of the guide plate, the conveyance is disturbed and a jam occurs. Since the fear increases, the roller pair needs to be hidden by the guide plate. FIGS. 10 (a) and 10 (b) show an embodiment for realizing such a purpose. A holder 16 supported vertically movably separately from the upper paper ejection guide plate 11 is shown.
(Supporting the upper discharge roller 13) with the upper solenoid 1
7a to retract above the lower surface of the upper guide plate 11, and to lower the lower discharge guide plate 12 to the lower solenoid 17b.
The lower paper discharge roller 14 is retracted from the paper surface by being rotated upward.

Next, the driven paper discharging roller 13 is supported by a holder 16 made of a leaf spring, and is pressed against the outer peripheral surface of the driving paper discharging roller 14. By this, the pressing force is secured and the conveyance force is obtained, but when the driven side discharge roller 13 is separated from the drive side discharge roller 14, the driven side discharge roller 13 is driven by the resilience of the leaf spring. It is easy to protrude to the paper passing side (see FIG. 11B). As a result,
Jams are likely to occur. In order to solve this problem, in the embodiment shown in FIG.
A guide rib is provided so as to be rotatable with respect to 2, and the guide rib limits the conveyance path of the recording paper so as not to be interfered by the ejection roller in a protruding state.

That is, reference numerals 50 and 51 in FIG.
Is a guide rib having a substantially triangular front shape. The guide rib is rotatably supported in a vertical direction by an appropriate position of each of the guide plates 11 and 12, and has angles θ1 and θ by a solenoid (not shown).
It is configured to rotate within the range of 2. The guide ribs have a predetermined width (width enough to guide the recording paper) in a direction orthogonal to the paper surface. The position of the rib indicated by the solid line is an appropriate position when the paper discharge roller loses the conveying force, and is oriented toward the paper passage gap formed between the pair of paper discharge rollers whose leading ends are open. Therefore, the recording paper can be discharged onto the discharge tray while being smoothly guided by the ribs without being interfered by the discharge rollers.

[0018]

According to the onset bright as the foregoing, since the spacing between the rollers constituting the pair of discharge rollers can be adjusted manually or automatically, the discharge roller spacing when discharging the cardboard enlargement As a result, it is possible to prevent a streak-like defective image from being formed due to the waist imparted by the sheet discharging roller pair. Also <br/>, when lost conveying force by opening the discharge rollers, the recording sheet to the discharge tray and the conveyor belt located in front of the discharge roller pair in cooperation with the suction means Since it can be sent out, there is no need for the user to perform a jam clearance or the like by putting his hand in the machine. Further, the opening of the discharge roller at the time of discharging the thick paper can be easily realized by a key operation from the operation panel, so that the operability can be improved. When a sorter is connected immediately after the paper discharge roller pair, the paper discharge roller pair can be always opened, so that an image without the paper discharge roller can be obtained. Further, since the paper discharge roller can be hidden behind the guide plate, it is possible to prevent the occurrence of a jam or the like due to the paper discharge roller protruding from the paper passing surface. Further, if the paper discharge range is regulated by guide ribs instead of hiding the paper discharge roller so that the paper discharge roller can directly enter the gap between the transport rollers, a jam can be prevented.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a front view and a side view showing a main part configuration of an embodiment of the present invention.

FIG. 2 is a front view showing the operation of FIG. 1;

FIG. 3 is a schematic diagram showing a modification of the embodiment of FIG. 1;

FIG. 4 is an explanatory diagram of a main part configuration of another embodiment of the present invention.

FIG. 5 is a schematic structural explanatory view of another embodiment of the present invention.

FIG. 6 is an explanatory diagram of a specific configuration of the embodiment of FIG. 5;

FIG. 7 is an explanatory diagram of a specific configuration of the embodiment of FIG. 5;

FIGS. 8A and 8B are flowcharts showing a control example for operating a paper discharge mechanism by an operation from an operation panel.

FIG. 9 is a view showing another example of the present invention, in which a sorter is arranged at a paper discharge port of a copying machine main body.

FIG. 10 (a) and (b) are other embodiments of the present invention,
FIG. 3 is a diagram illustrating a configuration example when a sorter is arranged at a paper discharge port of a copying machine main body.

FIGS. 11 (a) and (b) are explanatory diagrams of a configuration and a partial configuration of another embodiment of the present invention.

[Explanation of symbols]

1 fixing device, 2 fixing roller, 3 pressure roller, 10
Paper discharge mechanism, 11 upper discharge guide plate, 12 lower discharge guide plate, 13 upper discharge roller, 14 lower discharge roller, 15
Fulcrum , 16 holder, 17 solenoid, 18 spring, 19 paper output tray, 20 paper output cover, 21 separation claw, 25 cam, 30 transport belt, 31 suction fan,
33 ventilation pipe, 34 tube, 35 fan body, 4
0 solenoid, 45 image forming apparatus main body, 46 sorter, 47, 48 introduction roller, 50, 51 guide rib,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/00 510-534 G03G 15/20

Claims (5)

(57) [Claims] 1. A paper discharge port is provided with a pair of upper and lower paper discharge rollers.
Together, an image forming apparatus having a fixing device on the upstream side of the exhaust rollers, to <br/> to adjust the distance between the discharge roller by moving one of the discharge roller in the vertical direction Paper discharge path between the fixing device and the paper discharge roller pair
Place the upper and lower discharge guide plates with the
Means for adsorbing recording paper to one of the paper ejection guide plates
And a conveyance belt, and the conveyance force of the pair of paper discharge rollers is
Means for adsorbing the recording paper only when the value falls below a predetermined value;
A structure of a recording paper discharge section, comprising a control section for operating a transport belt . 2. The image forming apparatus according to claim 1, further comprising: a discharge roller trace elimination mode. When a discharge roller trace elimination mode key on an operation panel is turned on, the control unit shifts to a discharge roller trace elimination mode. structure of a recording sheet discharge unit according to claim 1, characterized in that the wide spacing of the discharge roller. 3. The structure of a recording sheet discharge section according to claim 1, wherein said discharge roller pair is always opened when a sorter is connected to said discharge port. 4. An image forming apparatus comprising: a pair of upper and lower discharge rollers at a discharge port; and a fixing device upstream of the pair of discharge rollers. Arrange the upper and lower discharge guide plates with the discharge path in between,
A structure of a recording paper discharge section, wherein each discharge roller is concealed by the discharge guide plate when the discharge roller pair is completely opened. 5. An image forming apparatus comprising a pair of upper and lower paper discharge rollers at a paper discharge port and a stationary device at an upstream side of the pair of paper discharge rollers, wherein the fixing device and the paper discharge roller pair are provided. Arrange the upper and lower discharge guide plates with the discharge path between
And a guide rib for guiding the recording sheet to a gap between the pair of discharge rollers when the pair of discharge rollers is completely opened.