JP2908063B2 - Paper ejection device of image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper discharge device of an image forming apparatus such as a copying machine, a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a sheet after an image forming process, for example, a sheet fixed by a heat fixing device as a last image forming process, is pressed against a first sheet discharging device. It is widely known that the paper is fed by passing between a paper discharge roller and a second paper discharge roller and discharged to a paper discharge tray or the like. Paper tends to curl upward during image formation, that is, curl upward at both side edges and curl upward. In particular, air containing steam is generated near the path of the sheet fixed by the fixing device. When this air is discharged out of the apparatus, as shown in FIG. 14, a cooling fan 101 for raising the temperature inside the apparatus is used, and air around the fixing device sucked through the exhaust duct 102 as shown by arrows B and C, and other air. And the air A sucked through the opening 105 into the paper discharge housing 104 are discharged through the ion removal filter 103 by the cooling fan 101. In this case, the amount of air sucked by the paper discharge housing 104 is reduced, and the amount of air sucked by the paper discharge housing 104 is further reduced at a position away from the cooling fan 101. Therefore, a difference in air flow occurs depending on the location in the paper discharge housing 104,
There is a disadvantage that the back curl becomes large at a position distant from the cooling fan 101.

[0003] Further, the exhaust fan in the machine is disposed on the lower side with respect to the paper path, the discharge housing is on the upper side,
The exhaust fan and the paper discharge housing are often located on opposite sides of the paper path. At this time, there is a problem that air containing water vapor evaporating on the upper surface of the fixed paper (recording paper) is blocked in the flow path by the paper, and the outside fan cannot be efficiently discharged by the exhaust fan. No effect.

[0004] Curled paper may cause damage or jam when stacked on a paper discharge tray.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a paper discharging device for removing curling of recording paper.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by providing an image forming apparatus having a first paper discharge roller and a second paper discharge roller which are pressed against each other, and which discharges a sheet after image forming processing. In the discharge device, an elastic impeller is disposed on both sides of one of the first discharge roller and the second discharge roller so as to be synchronously rotatable in the same direction as the roller, The impeller has an outer diameter dimension during rotation larger than the outer diameter of the roller, and the impeller has a width extending to a position exceeding the maximum sheet passing width, and is formed so as not to interfere with the roller. The problem is solved by the paper discharge device of the image forming apparatus.

The present invention solves the above-mentioned problem by providing a paper ejection device of an image forming apparatus having a first paper ejection roller and a second paper ejection roller which are pressed against each other, and which ejects a sheet sent from a fixing device. It has a first air intake / exhaust opening that supports a blower inside and faces the paper fed from the fixing device, and a second air exhaust / exhaust opening connected to a duct leading out of the image forming apparatus. The problem is solved by a paper ejection device of an image forming apparatus, wherein the housing is formed as a paper ejection roller housing that covers at least a part of any one of the paper ejection rollers.

[0008]

According to the present invention, since the impeller is made of an elastic material, the trailing edge of the recording paper in the discharge tray does not occur. In addition, the blades can come into contact with all the recording papers that can be passed.

According to the present invention, secondly, the curl is removed by sucking water vapor generated from the recording paper by a blower, or by quenching by blowing cooling.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on an embodiment shown in the drawings.

In FIG. 1, which shows a laser beam printer as an example of an image forming apparatus, a recording paper 2 fed from a paper feeder 1 in a pair of registration rollers is timed by a pair of registration rollers 3 to form a drum. Photoconductor 4
To the latent image carrier composed of The photoconductor 4 is driven to rotate in a counterclockwise direction. At this time, the surface is charged by a charging charger 5 and irradiated with laser light from a laser optical system 6 to form an electrostatic latent image on the photoconductor. This latent image is visualized by toner when passing through the developing device 7, and this visible image is transferred by a transfer charger 8 to paper (recording paper) 2 conveyed to a photoreceptor 4, and is transferred onto the transferred recording paper. The visible image is fixed by the fixing device 9. On the other hand, the residual toner is removed from the photoconductor 4 after the transfer of the visible image by the cleaning device having the cleaning blade 12. The toner removed from the photoconductor is collected in a toner collection tank 13.

The recording paper discharged from the fixing device 9 is rotated by a rotatable double-sided entrance guide 17 to form a pair of double-sided conveyance rollers 18.
Led to. The recording paper 2 is conveyed by a pair of double-sided conveying rollers 18 to a pair of reversing rollers 19 rotating clockwise, and passes through a reversing sensor 20. Recording paper 2 is reverse sensor 2
0, a predetermined time after passing, the reversing roller pair 19 changes the rotation direction in the counterclockwise direction, and the recording paper 2 is conveyed in the direction of the registration roller pair 3 by the rotatable reversing guide 21. The recording paper 2 fed again to the registration roller pair 3 is conveyed to the photoconductor 4 at a timing by the registration roller pair 3, and the toner is fixed on the recording paper through the same procedure as described above. At this time, since the surface opposite to the case where the paper is fed from the paper feeding device 1 is in contact with the photoconductor 4, double-sided recording is performed on the recording paper 2. After passing through the fixing device 9, the recording paper 2 on which double-sided recording has been performed passes through the double-sided entrance guide 17 and is discharged to the discharge tray 21 by the discharge roller device 11 and stored.

As shown in FIGS. 2 and 3, the discharge roller device 11 has a first discharge roller 31 and a second discharge roller 32 which are in contact with each other. The first discharge roller 31 has a shaft 31a,
It is formed by a plurality of roller pieces 31b fixed to the shaft 31a. Similarly, the second discharge roller 32 includes a shaft 32a parallel to the shaft 31a of the first discharge roller 31 and a plurality of roller pieces 32b fixed to the shaft 32a and opposed to the roller piece 31b of the first discharge roller 31. And is formed by

On the shaft 32a of the second discharge roller 32, rotating impellers 33 are provided on both sides of each roller piece 32b.
The rotary impeller 33 is formed of an elastic material, a resin such as polyethylene terephthalate, and is configured to rotate in the same direction as the second discharge roller 32 in synchronization with the second discharge roller 32.

The recording paper 35 is nipped between the first discharge roller 31 and the second discharge roller 32, fed, and stacked on a discharge tray 36. When the recording paper on the discharge tray 36 is full, the detection is detected by the movement of the detection filler 34 supported on the shaft 34a, and a detection signal is sent.

The rotating impeller 33 has a shaft 32 as shown in FIG.
and a plurality of (four in the figure) blades 33b fixed to the boss 33a.
Each blade 33b has a surface that extends tangentially to the boss 33a, and the surface that extends tangentially is guided by a guide 38 (FIG. 3) during rotation, as shown by the arrow in FIG. It is formed so as to be in contact with the recording paper.

As shown in FIG. 5, each rotating impeller 33
A paper discharge roller, for example, a roller piece 32 of the second paper discharge roller 32
b, intervals x ₂ and x ′ with respect to the detection filler 34, respectively.
₂ , y ₁ , y ₂ , y ₁ ′, y ₂ ′, and the outermost rotating impeller 33 has x ₁ , x ′ _{1 with} respect to the maximum sheet passing width Amax.
It is set only wide. The minimum sheet passing width Amin is set so as to be located at least within the range of the roller pieces 31b and 32b of the above-described discharge rollers 31 and 32.

Conventionally, upward curling is regulated by claw rollers provided near both side edges of the paper. However, in this method, when the amount of paper stacked on the paper discharge tray is increased,
The newly ejected sheet is caught between the notched roller and the notch in the surface of the rear support wall 37 of the sheet ejection tray 36, resulting in damage 39 at the rear end of the sheet as shown in FIG.

When the above-mentioned impeller 33 is used, the bundle of sheets curled upward is pressed downward by the elastic blades 33b. Next, the blade 33b of the elastic body reaches the notch in the support surface of the rear end support wall 37, the blade 33b is pressed against the wall of the notch, and the blade 33b bends, so that the force for winding the paper is reduced. As a result, the force of winding the trailing end of the sheet is released, and the damage as shown in FIG. 6 does not occur.

By setting the size of the impeller 33 as shown in FIG. 5, the outer width end of the impeller 33 is located outside the roller piece 32b and outside the maximum sheet passing width Amax, and is located near the roller piece 32b. Thus, the inner width end of the impeller 33 is in a range that does not interfere with the roller piece 32b. Thus, both ends of the sheet having the maximum sheet passing width Amax can be pressed.

In order to remove the curl of the sheet, an impeller 33 is provided as shown in FIG. 2, while the sheet is discharged from the fixing device 9 at the end of the image forming process as shown in FIG. Before reaching the discharge roller device by the transport means, a second discharge roller device including a pair of a third discharge roller 44 and a fourth discharge roller 45 is provided.

The second discharge roller device is a third discharge roller 44.
Paper discharge housing 4 having an opening surrounding at least a part of
One. A blower, for example, an exhaust fan 42 is provided in the paper discharge housing 41. The paper discharge housing 41 is provided with a first opening 43 for suction and discharge, for example, a suction port 43 so as to face the paper discharged from the fixing device 9.
The other parts are basically the same as those in FIG. 1, and the same or corresponding parts are denoted by the same reference characters and description thereof will be omitted.

FIG. 8 is a plan view showing the arrangement of the paper discharge housing 41. In the housing 10 of the image forming apparatus, the paper discharge housing 41 is positioned in the depth direction of the apparatus (vertical direction in the figure).
Has been extended. Reference numeral 36 denotes a paper discharge tray, and reference numeral 1 denotes a paper feeding device. In this figure, a first opening (suction port) 43 is provided on the right side of the paper discharge housing 41. Further, a duct (for example, an exhaust duct) 47 is provided on the back side (upper side in the figure) of the paper discharge housing 41. A second opening (not shown) (a second opening for exhaust, for example, an exhaust port) is provided at a far end surface of the paper discharge housing 41 in contact with the duct 47, and an exhaust fan 42 is installed near the second opening. An ozone removal filter 48 is provided at an opening of the duct 47 facing the outside of the apparatus.
Thus, the paper discharge housing 41 is formed so as to be able to exhaust to the outside via the duct 47 and the ozone removal filter 48.

Air containing water vapor released from the recording paper 2 after fixing is sucked by the exhaust fan 42 through the first opening 43 and exhausted through the exhaust duct 47. The paper discharge housing 41 has a closed structure except for the opening described above.

Since the exhaust fan 42 is arranged in the paper discharge housing separately from the fan for discharging the air in the apparatus, a large air volume can be obtained in the paper discharge housing. In the discharge housing, a uniform and sufficient air volume was obtained at any location. Therefore, the bias of the back curl is also reduced.

When the sheet 2 that has passed through the fixing device 9 enters the second sheet discharging roller device at an entering angle of θ with respect to the sheet discharging direction from the second sheet discharging roller device, if the sheet 2 enters at a high temperature, Is rolled by the entrance angle θ, and as a result, a U-shaped back curl is generated. However, since air containing water vapor is sucked into the paper discharge housing 41 and the sheet is rapidly cooled, the back curl is given even if the entrance angle of θ is given. Is less likely to occur.

As the exhaust fan 42, a small axial fan can be used. When the exhaust fan 42 is a DC-driven axial fan, a control circuit as shown in FIG. 9 is provided,
The DC stabilized power supply 49 and the exhaust fan 42 are
And a drive voltage switch 51. The drive voltage for the exhaust fan 42 is switched by switching the changeover switch 51.

The PQ characteristic curve of the axial fan is as shown in FIG. By increasing the drive voltage, the wind pressure (air volume) increases in the order of the curves Q1, Q2, and Q3 under the same static pressure.

The switching between the high drive power supply voltage (H) and the low drive power supply voltage (L) via the dummy resistor 50 can be performed by switching the changeover switch 51 shown in FIG.

By switching the air volume, when the power of the fixing device increases, such as when the printing speed increases,
Air containing water vapor becomes hotter. In such a case, the switch 51 is switched to the high drive power supply voltage (H). The amount of cooling air increases in response to the increase in the amount of generated heat, and back curl is suppressed. As a result, there is no need to individually select a fan according to the model, the design cost is reduced, and the unit price of the fan due to the mass production effect is reduced. or,
The amount of service parts required has been reduced, and the cost of maintenance has been reduced.

In the case of printers of the same series having different printing speeds, the output of the heat fixing device may be changed, and the amount of generated steam increases or decreases according to the output of the heat fixing device. When the amount of generated steam changes, the curl of the sheet also changes. This point has been solved by switching the air volume of the fan.

As shown in FIG. 11, it is possible to switch the blower from the exhaust fan 42 to the cooling fan 42 'as shown in FIG. In this case, the first opening functions as an air outlet in FIG. 11 instead of the suction port in FIG. 7, and the second opening functions as a suction port in FIG. 11 with respect to the exhaust port in FIG.

As shown in FIG. 12, the paper discharge housing 41 '
The cooling fan 42 'can take in cooling air from the outside through the cooling fan duct 47', and can be configured to be dispersed by the louver 57 and to blow out the air from each outlet 43 'almost uniformly.

The air blown out from the blow-out port 43 'is blown out toward the sheet 2 discharged from the fixing device 9, so that the sheet can be cooled rapidly.

The length L ₁ of the area of the outlet 43 ′ of the paper discharge housing 41 ′ is set so that L ₁ ≧ L ₂ with respect to the width L ₂ of the recording paper 2.

The blower is replaced with the axial fan of FIG.
A cross flow fan 42 "can be used as shown in FIG.

In this case, the cooling fan duct 47 "is
For the second example, the air flow is deformed so as to be smoothly obtained. The length L ₃ of the cross flow fan has a relationship of L ₃ ≧ L ₂ with the width L _{2 of the} recording paper.

[0038]

According to the present invention, the impeller is made of an elastic material, so that the trailing edge of the recording paper in the paper discharge tray does not occur. In addition, the blades can come into contact with all the recording papers that can be passed.

According to the second aspect of the present invention, the air containing water vapor generated from the recording paper after the image processing is sucked in to rapidly cool the paper, so that the back curl is hardly generated even if the paper ejection guide is curved upward.

It is possible to orderly discharge paper curled upward in all paper sizes from the maximum sheet passing width to the vicinity of the roller and from the vicinity of the roller to the vicinity of the detection filer.

According to the present invention, since the air sucked from the outside is blown against the paper passing through the paper passage from the exit of the fixing device to the paper discharge roller device, the paper in the high-temperature and high-humidity state is directly cooled rapidly. Can be. As a result, the paper changes from a semi-dry state to a dry state, and even if the subsequent paper transport path is curved, it is possible to suppress the paper curl, that is, the U-shaped back curl.

According to the present invention, if a cross flow fan having an axis parallel to the axis of the paper discharge roller is provided, the fan length is set to be equal to or greater than the width of the paper. A large amount of air can be blown uniformly on a partial surface perpendicular to the transport direction of the sheet passing through the path to the apparatus without a difference in air volume. As a result, the temperature gradient on the cooling surface of the paper is eliminated, so that even if the paper transport path is curved, it is possible to suppress the occurrence of the bias of the back curl.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an image forming apparatus according to the present invention.

FIG. 2 is a side view of the sheet discharging device.

FIG. 3 is a front view of the sheet discharging device.

FIG. 4 is a perspective view of an impeller.

FIG. 5 is a plan view of the sheet discharging device.

FIG. 6 is a diagram showing breakage of a conventional sheet.

FIG. 7 is a schematic view of the vicinity of a sheet discharging device according to another embodiment of the present invention.

FIG. 8 is a schematic plan view of a main part.

FIG. 9 is a control schematic diagram of a blower according to the present invention.

FIG. 10 is a characteristic curve diagram of the blower.

FIG. 11 is a diagram corresponding to FIG. 7 of another example.

FIG. 12 is a diagram corresponding to FIG. 8 of the example of FIG. 11;

FIG. 13 is a view corresponding to FIG. 12, showing a modification of the blower.

FIG. 14 is a schematic plan view of a conventional example.

[Explanation of symbols]

 2 Recording Paper 9 Fixing Device 11 Discharge Unit 31 First Discharge Roller 32 Second Discharge Roller 33 Impeller 41, 41 ′ Discharge Housing 42, 42 ′, 42 ″ Blower 43, 43 ′ Suction and Exhaust Port 44 Third Discharge roller 45 Fourth discharge roller 47, 47 'Duct

Continuation of front page (56) References JP-A-63-154570 (JP, A) JP-A-62-85264 (JP, A) JP-A-57-99677 (JP, A) JP-A-2-28462 (JP) , A) Japanese Utility Model Hei 2 2-69663 (JP, U) Japanese Utility Model Application Sho 59-138864 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65H 29/22 B65H 31/34

Claims (6)

(57) [Claims] A first discharge roller and a second discharge roller which are pressed against each other;
An image forming apparatus that has a sheet discharging roller and discharges the sheet after the image forming process, wherein the roller is disposed on both sides of one of the first sheet discharging roller and the second sheet discharging roller. Has an impeller of an elastic body arranged so as to be synchronously rotatable in the same direction as the above, the outer diameter of the impeller during rotation is larger than the outer diameter of the roller, and the impeller has a maximum paper passing width. A sheet discharging device for an image forming apparatus, wherein the sheet discharging device has a width extending to a position beyond the roller and is formed so as not to interfere with the roller. A first discharge roller and a second discharge roller which are pressed against each other;
A sheet discharging device of an image forming apparatus for discharging a sheet sent from a fixing device and having a sheet discharging roller, wherein an air blower is supported inside and a suction / discharge device is disposed facing the sheet sent from the fixing device. A housing having a first opening for discharge and a second opening for discharge and intake connected to a duct leading out of the image forming apparatus is formed as a discharge roller housing that covers at least a part of one of the discharge rollers. A sheet discharging device for an image forming apparatus. 3. The sheet discharging device according to claim 2, wherein the rotation speed of the blower is variable by voltage switching by a driving voltage switching unit. 4. The air conditioner according to claim 2, wherein the blower is formed as an exhaust fan, the first opening is formed as a suction port, and the second opening is formed as an exhaust port.
2. The sheet discharging device of the image forming apparatus according to claim 1. 5. The air blower is formed as a blower fan, the first opening is formed as an outlet, and the second opening is formed as a suction port, and the blower blows the cooling air over a full width of the sheet. 3. The sheet discharging device of the image forming apparatus according to claim 2, wherein the sheet is formed so as to be sprayed substantially at right angles to the sheet conveying surface. 6. The fan according to claim 1, wherein said blower is formed as a cross-flow fan, and an axis of said fan is arranged parallel to said discharge roller, and said fan extends at least in a range of the same paper width. Item 6. A sheet discharging device for an image forming apparatus according to Item 5.