JPH054731A - Sheet feeder - Google Patents

Abstract

PURPOSE:To feed envelopes automatically and smoothly, especially at the time of feeding a large quantity of sheets in a sheet feeder for picture image forming device such as a laser printer. CONSTITUTION:There is provided a spring 18 which supports an end fence 20 which pushes approximately ten envelopes from the top of a bundle 13 of envelopes plied up on a sheet bundle deck 10 for large quantity of sheets feeder, and an auxiliary bottom plate 17 which receives a bundle 13' of envelopes which is pushed by the end fence upward and makes the bundle 13' of envelopes come into pressure contact with the upper surface of a sheet feed roller 7, the spring repeats the operation whenever envelopes run out onto the auxiliary bottom plate. Because the bundle of envelopes on the auxiliary bottom plate is small, both the edges of the envelopes do not rise up even if envelopes are piled up, providing smooth sheet feed. In an ordinary sheet feed cassette, it is possible to prevent both edges of envelopes from rising by pressing down both edge parts of envelopes with the peripheral surface of an inclined cylindrical roller or a tapered roller which is provided with a horizontal shaft for smooth sheet feed. The sheet feed roller may be also used as the above purpose also, or used as a sub-roller provided installed in addition to the sheet feed roller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for an image forming apparatus, and more particularly to a sheet feeding device suitable for feeding envelopes.

[0002]

2. Description of the Related Art As a sheet feeding device such as a printer or an electrophotographic copying machine, the upper surface of a sheet bundle stacked on a sheet bundle mounting table is pressed against a sheet feeding roller, and the sheet feeding roller is moved in response to a sheet feeding signal. 2. Description of the Related Art A paper feeding device is generally used in which paper is fed sequentially from the top of a bundle of papers by rotating.

FIG. 10 shows an example of the overall configuration of a laser printer provided with such a sheet feeding device. This laser printer 1 includes two ordinary paper feed cassettes 2 and a large-scale paper feed device (Large Paper Feed) as an optional device.
Capacity Imput Tray (LCIT) 3 is combined.

FIG. 11 shows in detail the constructions of the sheet feeding cassette 2 of this apparatus and the sheet feeding section of the apparatus main body 1. This paper feeding device employs a paper feeding mechanism called an FRR (Feed and Reverse Rollers) system, which is said to be relatively excellent in terms of a double-fed separation / paper feeding function.

The movable bottom plate 4 of the paper feed cassette 2 is pushed up by a pressure lever 5, and the upper surface of the sheet bundle 6 placed on the movable bottom plate 4 is picked up by a pickup roller (paper feed roller) 7 provided in the main body of the apparatus. The sheet bundle 6 is brought to a position where it can be pressure-contacted, and the sheet feeding roller 7 is rotated according to the sheet feeding signal, so that the sheet bundle 6
Paper is fed in sequence from above. Paper feed direction 7
On the downstream side, the feed roller 8 rotating in the paper feeding direction and the paper feeding path are sandwiched and pressed against this, and can be rotated in either forward or reverse directions, and a constant torque is applied in the opposite paper feeding direction via a torque limiter. There is provided a roller pair consisting of an applied reverse roller 9.

With this structure, when one sheet of paper is fed by the paper feed roller 7, the reverse roller 9 is driven by the feed roller and is fed without slippage between the paper and the roller. If more than one sheet of paper is fed, the friction between the paper and the roller is greater than the friction between the paper, so only the paper that slides between the paper and contacts the feed roller is fed by the feed roller. The lower sheet is pushed back to the sheet feeding cassette side by the torque in the direction opposite to the sheet feeding direction, and double feeding is prevented.

The paper feeding and double feeding separating mechanism of the LCIT3 has the same structure. However, since the LCIT allows a large amount of sheets to be stacked, the range of elevation of the sheet tray 10 on which the sheet bundle 6 is placed is much larger than that of the movable bottom plate of the ordinary sheet cassette 2, and the motor 11 is used. As a drive source, it is configured to move in the vertical direction via a belt 12 or a wire, and the height of the upper surface of the sheet bundle is detected by a sensor (not shown) so that the upper surface of the sheet bundle can always be pressed against the sheet feeding roller 7. The start / stop of the motor 11 is controlled so that the motor 11 is held within a predetermined range.

By the way, in recent years, especially for laser printers, diversification of printing paper has progressed, and even if the thickness of the envelope is not uniform, the printed matter on the sheet is not cut and stuck. The demand for direct printing is increasing.

However, the envelope not only has a non-uniform thickness, but also has a bulge in the thickness direction due to air inside, so that the envelope is on the movable bottom plate of the paper feed cassette or LC.
When stacked on the IT sheet stacking stand, due to the non-uniformity of the thickness of each envelope, the thickness of both sizes with flaps and folds is particularly large. As shown in FIG. 12, many sheets are stacked. When the upper surface of the envelope bundle 13 is pressed by the paper feed roller 7, since the paper feed roller 7 has a short length and is normally provided only at one location on the center line, the upper surface does not have a uniform flat state. Both sides in the transport direction are raised. Therefore, in the vicinity of the center of the envelope with which the paper feed roller 7 abuts, the envelope comes into elastic contact with the paper feed roller, and particularly in the case of an envelope having a high coefficient of friction, the envelope is rotated when the paper feed roller starts to rotate. A paper jam that escapes from the paper feed roller may occur. Although it is possible to achieve some improvement by increasing the pressing force of the paper feed roller, in the case of envelopes and plain paper with a low coefficient of friction, the applied pressure will result in double-feeding jams, and various paper types. There was a difficulty that I could not deal with.

When stacking envelopes, it is advantageous to use the LCIT because it is not possible to stack a large amount in an ordinary paper feeding cassette due to the bulging in the thickness direction as described above, but in that case, as shown in FIG. When the paper feed roller is pressed against the upper surface, the lifting of both side edges becomes even larger, and if a normal paper feed operation is performed in this state, both sides will be caught in the paper feed inlet and cause a jam. Due to the resilience, there is a problem that the envelope escapes downward and does not feed, and it is practically impossible to feed the envelope from the normal LCIT.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems when an envelope is fed by a sheet feeding device of an image forming apparatus such as a laser printer, the present invention smoothly feeds a large amount of envelope bundles. A first object is to provide a large-volume paper feeding device that can carry paper, and a paper feeding device that can feed envelopes from a normal paper feeding cassette without jams such as double feeding and non-feeding. The second problem is to provide.

[0012]

SUMMARY OF THE INVENTION A mass-feeding device for solving the above-mentioned first problem is an upper end of the ascending / descending range of the above-mentioned sheet stacking table and a portion thereof from the range in which the sheet stacking table spreads, in front of the sheet feeding direction. The lower limit of the displacement range of the auxiliary bottom plate, which is displaceable downwardly from an appropriate amount and urged upward in a releasable manner, and the auxiliary bottom plate of the sheet stack placed on the sheet stack mounting table. And a means for moving the upper sheet bundle in the sheet feeding direction onto the auxiliary bottom plate, and the sheet feeding roller is located at a position suitable for feeding from the sheet bundle placed on the auxiliary bottom plate. In the sheet feeding device for solving the second problem, the sheet feeding roller is a cylindrical roller,
It is arranged on an axis inclined with respect to the paper feed plane so that its cylindrical surface contacts with both side edges of the sheet bundle at an angle with the paper feed plane, or the paper feed roller is on one axis extending in the horizontal direction. A pair of frusto-conical rollers provided in a pair of rollers, and the pair of rollers are arranged such that the small diameter portions are opposed to each other and the conical surfaces are in contact with both side edges of the sheet bundle. And

Further, in addition to the paper feed roller, driven rollers whose peripheral surface can be pressed against the paper feed surface at a certain angle may be provided at both upper end edges of the stacked sheet stack.

[0014]

According to the former configuration, when the sensor detects that the upper surface of the envelope bundle stacked on the sheet bundle placing table has reached a predetermined position, the sheet bundle placing table stops rising, and The envelope located between the envelope and a proper position downward is pushed out by the moving means in the sheet feeding direction, and is moved onto the auxiliary bottom plate from which the upward biasing force is released. Then, an urging force is applied to the auxiliary bottom plate, and the upper surface of the envelope bundle above the auxiliary bottom plate is pressed against the paper feed roller. Since the amount of envelope bundle on the auxiliary bottom plate is appropriate, both side edges will not be improperly lifted even when pressed by the paper feed roller.
Each time the paper feed roller rotates in response to the paper feed signal, paper is fed sequentially from above.

When the envelope on the auxiliary bottom plate disappears, the auxiliary bottom plate descends, the sheet loading table rises earlier than this, and a predetermined amount is again placed on the auxiliary bottom plate from the envelope bundle whose upper surface is at a predetermined height position. It is moved and paper feeding is continued.

According to the latter construction, the cylindrical surface of the cylindrical paper feed roller whose axis is inclined with respect to the paper feed plane or the pair of truncated cone conical surfaces whose axes are parallel to the paper feed plane is provided. Since both ends of the envelope bundle are pressed against each other, both ends of the envelope bundle are pressed so as to be as horizontal as possible without being lifted, and the envelope paper surface escapes from the paper feed roller, which was caused by the elasticity of the center of the envelope. Can be reliably fed.

Further, when the peripheral surface of the driven roller provided separately from the paper feed roller is pressed against both side edges of the envelope bundle and the paper is fed by the paper feed roller, the same effect can be obtained.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an LCI as a first embodiment of the present invention.
It is a figure which shows schematic structure of T. In the figure, members having the same functions as those of the LCIT described with reference to FIG.

A sheet bundle 1 placed on the sheet bundle mounting table 10.
A sensor 15 for detecting that the upper surface of 3 has reached a predetermined upper limit position is provided. The detection signal controls the start / stop of the motor not shown in FIG. The upper surface of the sheet bundle is always held at a predetermined height position.

The front backing plate 16 of the LCIT is omitted from the above predetermined height position to the height position at a predetermined lower distance. An auxiliary bottom plate 17 is provided in front of the front contact plate 16 in the sheet feeding direction so as to be freely displaceable from a height position of the upper end of the front contact plate 16 to a position where it can contact the sheet feeding roller 7 at the sheet feeding position. Has been. The auxiliary bottom plate 17 can be biased upward by a spring 18 from below, and the biasing force of the spring on the auxiliary bottom plate 17 is released by displacing the member 19 attached to the lower end of the spring 18 downward. The sheet stacking table 10 is designed so as not to rise above the lowest position of the auxiliary bottom plate 17, that is, the upper end position of the front contact plate 16.

The abutting surface 20a can be moved a suitable distance in the direction of arrow A from the position where the abutting surface 20a comes to the position rearward of the rear end of the paper-bundle placing table 10 in the paper-bundle loading range, and the abutting surface 2
An end fence 20 having 0a in a height range corresponding to the moving range of the upper surface of the auxiliary bottom plate 17 is provided.
The height of the abutting surface of the end fence 20 is set to be about 10 normal envelopes loaded in a free state.

The operation of feeding an envelope using this LCIT will be described below with reference to FIGS. 1, 2 and 3.

First, the sheet bundle placing table 10 is lowered to the lowest position, and the envelope bundle 13 is placed thereon. When the door of the LCIT is closed, the motor is energized, the sheet stacking table 10 rises,
The sensor 15 detects the upper surface of the envelope bundle 13 placed thereon, and the detection signal causes the motor to stop, so that the sheet bundle placing table 10 stops rising. At this time, the auxiliary bottom plate 17 is at the lowest position, and the biasing force of the spring 18 is released.

FIG. 1 shows this state.

Next, the end fence 20 moves in the direction of the arrow A, and the end fence 20 is in the height range of the abutting surface 20a.
The envelope of about one sheet is pushed forward by the end fence 20, and when the sensor (not shown) detects that the front end of the envelope comes to the position corresponding to the front end of the auxiliary bottom plate 17, the end fence 20 stops and the paper feeding roller 7 End fence 2
0 is pushed down to a predetermined position in contact with the upper surface of the envelope bundle 13 '. On the other hand, the spring 1 for urging the auxiliary bottom plate 17
The member 19 to which the lower end of 8 is attached rises, and the spring 18 pushes up the auxiliary bottom plate 17 so that the upper surface of the bundle of envelopes 13 'comes into pressure contact with the paper feed roller 7. FIG. 2 shows this state. At this time, since there are about 10 envelope bundles 13 ′ placed on the auxiliary bottom plate, even if the sheet feeding roller 7 presses the vicinity of the center line of the upper surface, both end portions become large as shown in FIG. The paper is not lifted up, and is smoothly fed by the paper feed roller 7 that rotates in response to the paper feed signal. There is no risk of non-feeding or jamming, and stable paper feeding is possible.

When the envelopes are fed from the state shown in FIG. 2 and the last one envelope of the envelope bundle 13 'is fed as shown in FIG. 3, the envelope bundle upper surface detection sensor 15 causes the envelope bundle 13'.
The end fence 2
0 is retracted in the direction of arrow B, the auxiliary bottom plate 17 is retracted in the direction of arrow C together with the biasing spring 18 and its mounting member 19, and then the sheet bundle loading table 10 is again loaded with the envelope bundle 1 placed thereon.
3, the motor is moved up by the motor, and when the upper surface of the envelope bundle is detected by the sensor 15, the sheet bundle mounting table 1 is detected by the detection signal.
The rise of 0 is stopped, the state shown in FIG. 1 is restored, and the series of operations described above is restarted. The double feed of envelopes fed is separated by the feed roller 8 and the reverse roller 9.
In this way, a large amount of envelopes stacked on the LCIT sheet stacking table 10 can be automatically and smoothly fed to the end.

Next, a second embodiment in which an envelope can be fed by a paper feed cassette directly attached to the main body of the image forming apparatus will be described with reference to FIG.

In this embodiment, the center line of the envelope bundle 13 is closer to the center line of the envelope bundle 13 than the opposite sides of the envelope bundle 13 placed on the paper feed cassette so that the cylindrical surfaces come into contact with both side edges 13a of the envelope bundle 13. It is provided so as to rotate integrally with the shaft 22 inclined upward. Therefore, the bundle of envelopes loaded in the paper feed cassette is pressed by the paper feed rollers 21 at both side edges so that the envelopes can be smoothly fed without the both side edges being lifted. You can

FIG. 6 shows the paper feed roller 21 in the above embodiment.
An example of a mechanism in which the shaft 22 that supports the rotatably driven by freely changing the inclination angle is shown. The shaft 22 is rotatably supported by a bearing member 23 that also serves as a load base, and a bevel gear 24 is fixedly provided at an end of the paper feed roller 21 opposite to the mounting end thereof. A drive shaft 26, which meshes with the bevel gear 24 and has a bevel gear 25 having an axis orthogonal to the axis of the bevel gear 24, fixed at one end, is rotatably supported by the bearing member 23. The drive shaft 26 is rotatably supported by a bearing (not shown) at a position fixed to the main body of the apparatus, and the bearing member 23 is rotatably supported by the drive shaft 26. The bearing member 23 is biased by a compression spring 27 in a direction in which the sheet feeding roller 21 is pressed against the side edge of the envelope bundle 13 and is swung in the direction of arrow D by a solenoid (not shown) or the like to envelop the sheet feeding roller 21. The side edges of the bundle 13 can be brought into and out of contact with each other.

Therefore, the bearing member 23 is tilted by the solenoid or the like so that the envelope side is lifted, the envelope bundle 13 is placed in the cassette, and then the solenoid or the like is de-energized. Is urged in the direction of lowering the envelope bundle side, and the cylindrical surface of the paper feed roller 21 presses both side edges 13a of the envelope bundle 13 at an angle with respect to the paper feed surface. In this state, if the drive shafts 26 on both sides are rotated at the same speed in synchronization with the sheet feeding signal, the sheet feeding rollers 21 on both sides are rotated.
Exerts a conveying force on the envelopes at the same peripheral speed, and the envelopes are sequentially delivered from above without being obliquely fed.

In the third embodiment shown in FIG. 7, the left and right paper feed rollers 30 are frustoconical in shape, and the envelopes are bundled on a single shaft 31 orthogonal to the paper feed direction with their small diameter sides facing each other. It is provided at symmetrical positions with respect to the center line of the envelope bundle so as to hang on both side edges of 13. Therefore, the paper feed roller 30 forms a certain angle with the paper feed surface by its conical surface, and both side edges 1 of the envelope bundle 13 are formed.
3a is pressed with an equal pressing force to prevent both sides of the envelope 13 from jumping up, and the sheets can be sequentially fed from above without skew feeding. In the case of this embodiment, since the axis of the sheet feeding roller 30 is horizontal, the driving mechanism thereof does not need any special one and can be simplified.

However, when the width of the envelope changes, the position of the conical surface that contacts the edge of the bundle of envelopes changes, and the radius of the contact circle changes, so that the feeding speed changes. Therefore, it is not appropriate to use this configuration for a model that requires strict accuracy in sheet feeding timing and the like.

However, in both the third and fourth embodiments, if the length of the paper feed roller is increased, even if the width of the envelope changes, the same roller can suffice.

In the fourth embodiment shown in FIG. 8, the sheet feeding mechanism has a sheet feeding roller 7 pressed against the front portion of the upper surface of the sheet bundle and a feed roller provided on the downstream side thereof, as in the conventional ordinary sheet feeding device. 8 and the reverse roller 9, but in addition to this, in the case of feeding envelopes, the cylindrical surface is pressed against the upper end edges 13a of both sides of the envelope bundle 13 at a certain angle with the paper feeding surface. A cylindrical driven roller 40 is rotatably supported on both sides by a shaft 41 which is swingable in a plane perpendicular to the sheet feeding direction. With this structure, both ends of the envelope bundle are driven by the driven roller 40.
This prevents the sheet from being pushed down and lifted up, and the sheet is fed by the sheet feeding roller 7 as usual. In this embodiment, the driven roller is inclined and comes into pressure contact with the side end edge of the envelope bundle, but it is not necessary to transmit power to the shaft, so that the structure is very simple.

In the fifth embodiment shown in FIG. 9, instead of the obliquely arranged cylindrical driven rollers in the fourth embodiment, the truncated cone-shaped driven rollers 42 are symmetrical with respect to the center line of the envelope bundle mounting position. One horizontal shaft 43 so that the small diameter sides face each other and the conical surface presses the end edge 13a of the envelope bundle 13.
It is rotatably installed. In this embodiment, if the size of the envelope changes, the position of the driven roller 42 in contact with the edge of the envelope bundle changes, and the rotation speed of the driven roller 42 changes. However, since it is a driven roller, its shaft 43 rotates. It is not necessary, and since the paper feeding is performed by the paper feeding roller 7 rotating at a constant speed, the paper feeding speed is kept constant.

In the paper feeding device of each of the above embodiments, it is of course possible to feed normal paper.

[0038]

As described above, according to the configuration of the present invention as set forth in claim 1, even when a large number of envelopes are placed on a large-volume sheet feeding device and fed in a large amount, both side ends are not greatly lifted and stable. In addition, according to the invention of the configurations described in claims 2 to 6, the envelope can be fed without jamming such as double feeding or non-feeding from the normal paper feeding cassette. can do. Each of these paper feeding devices can also perform normal paper feeding without any trouble.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining the operation together with FIGS. 1 and 3.

FIG. 3 is a cross-sectional view for explaining the operation together with FIGS. 1 and 2.

FIG. 4 is a schematic diagram for explaining the effect of the first embodiment.

FIG. 5 is a perspective view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 6 is a perspective view showing an example of a mechanism for rotatably supporting and rotatingly supporting the shaft 22 of the second embodiment.

FIG. 7 is a perspective view showing a configuration of a third exemplary embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 9 is a perspective view showing the configuration of a fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view showing the overall configuration of an example of a known laser printer.

FIG. 11 is a cross-sectional view showing the configuration of the paper feeding unit.

FIG. 12 is a cross-sectional view illustrating a problem when an envelope bundle is stacked on the paper feeding unit.

FIG. 13 is a cross-sectional view illustrating a problem when an envelope bundle is stacked on a large-volume sheet feeding device.

[Explanation of symbols]

1 laser printer 2 paper feed cassettes 3 Mass Paper Feeder 4 movable bottom plate 6 paper bundle 7 Paper feed rollers 10 Paper stacking stand 13 envelope bundles 17 Auxiliary bottom plate 20 End fence (transportation) 21 Cylindrical paper feed roller 30 truncated cone paper feeding roller 40 Cylindrical driven roller 42 follower cone-shaped driven roller

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/00 109 7369-2H

Claims (6)

[Claims] 1. The sheet stacking table is raised so that the upper surface of the sheet stack stacked on the sheet stacking table that can be raised and lowered is at a predetermined sheet feeding position where the sheet feeding roller can feed the sheet. In a mass-feeding device that feeds sheets in order from the top of the sheet bundle, the range of elevation of the upper surface of the sheet bundle placed on the above-mentioned sheet bundle placing table in the feeding direction forward of the range in which the above-mentioned sheet bundle placing table expands. An auxiliary bottom plate that is displaceable between the upper end of the and an appropriate lower position and is urged upward in a releasable manner;
Means for moving a sheet bundle above the lower limit of the displacement range of the auxiliary bottom plate of the sheet bundle placed on the sheet bundle mounting table in the sheet feeding direction onto the auxiliary bottom plate, A mass-feeding device, wherein the roller is provided at a position suitable for feeding from a bundle of sheets placed on the auxiliary bottom plate. 2. A sheet feeding device of an image forming apparatus, wherein a sheet feeding roller is pressed against a top surface of a sheet bundle stacked on a sheet feeding table and rotated to feed sheets in order from the top of the sheet bundle. The roller is a cylindrical roller, and is arranged on an axis inclined with respect to the sheet feeding plane so that the cylindrical surface comes into contact with both side edges of the sheet bundle at an angle with the sheet feeding plane. And a paper feeder. 3. A sheet feeding device of an image forming apparatus, wherein a sheet feeding roller is brought into pressure contact with an upper surface of a sheet bundle stacked on a sheet feeding table to rotate the sheet bundle and the sheets are sequentially fed from above the sheet bundle. The rollers are a pair of frusto-conical rollers provided on one axis extending in the horizontal direction. The pair of rollers have their small diameter portions facing each other so that the conical surfaces abut on both side edges of the sheet bundle. A sheet feeding device characterized in that the sheet feeding device is arranged in. 4. A sheet feeding device of an image forming apparatus, wherein a sheet feeding roller is brought into pressure contact with an upper surface of a sheet bundle stacked on a sheet feeding table to rotate the sheet bundle and the sheets are sequentially fed from above the sheet bundle. A sheet feeding device characterized in that driven rollers are provided on the upper edges of both sides of the sheet bundle, the driven rollers of which the circumferential surface can be pressed against the sheet feeding surface at an angle. 5. The sheet feeding device according to claim 4, wherein the driven roller is a cylindrical roller rotatably supported by a shaft having a variable tilt angle. 6. A frusto-conical roller in which the driven roller is rotatably supported by a horizontal shaft which is movable in the vertical direction, and the small diameter portions are opposed to each other. The paper feeder described.