JP2000255809A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed even humidified sheets of paper without problems in a paper feeding device such as a printer. SOLUTION: A turn roll shaft 40 rotatably bears a leg portion 44A of a substantially rectangular weight bar 44. A loading portion 46 located at a leading end of the weight bar 44 presses a leading end of a sheet of paper P, thereby suppressing the sheet of paper P from waving, even if the sheet of paper P is humidified to wave at a leading end thereof. Further, the loading portion 46 of the weight bar 44 is arranged in the vicinity of a corner nail 38, thereby surely preventing the sheet of paper P from waving in the vicinity of the corner nail 38, which surely enables the sheet of paper P to ride on the corner nail 38. Besides, a cassette 28 has a supporting portion below the corner nail 38 all over inside a leading end thereof, to which supporting portion the leading end of the sheet of paper P abuts. Accordingly, even if it is humidified, the sheet of paper P is prevented from crawling into an innermost between an inner wall of the cassette 28 and the leading end of the sheet of paper P.

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 used for an image forming apparatus such as a copying machine and a printer.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Is provided with a feed roll 82 that feeds the paper P and a paddle 84 that increases the transport force of the paper P. A corner claw 88 is provided at the tip corner of the cassette 86 of the paper feeding device 80 to hold the tip corner of the paper P.

On the other hand, when the paper P is conveyed by the feed roll 82 and the paddle 84, the corners of the leading end of the paper P pressed by the corner claws 88 get over the corner claws 88 and are separated one by one. And a mechanism for feeding paper to the turn roll 90 side.

As a factor for improving the running performance of the paper feeding device 80 with respect to various types of paper P, the paper P must have an appropriate stiffness and have no surface waving or the like.

However, if the paper P is left in the cassette 86 in a high humidity state such as a summer environment, the paper P absorbs moisture and the paper P loses its stiffness, and the surface of the paper P has a wavy shape as shown in FIG. I will hit you.

When the paper P is fed as described above, FIG.
As shown in FIG.
It gets into the back along 6A, and corner nail 8
8 cannot be passed, and the paper P is not fed.
For this reason, a jam or a dog year occurs.

[0007]

SUMMARY OF THE INVENTION In view of the above fact, it is an object of the present invention to be able to feed moisture-absorbed paper without any problem in a paper feeding device such as a printer.

[0008]

According to the first aspect of the present invention, a sheet feeding means is disposed above a stacking plate on which sheets are stacked, and feeds the uppermost sheet abutting thereon. Also,
Separating means is provided on the leading end side of the stacking plate to separate the stacked sheets. The leading end of the paper separated by the separating means is pressed by the load means.

For this reason, even if the paper has no stiffness due to moisture absorption and has a wavy surface, the waving is suppressed by pressing the leading end of the paper by the loading means, and the leading end of the paper is more squeezed than when no loading means is provided. Since the stiffness is obtained, the sheet is fed over the separating means.

According to the second aspect of the present invention, the load means is provided near the separating means.

As a result, the waving of the sheet near the separating means is suppressed, and the stiffness of the leading end of the sheet can be further increased, so that the sheet can surely pass over the separating means.

According to the third aspect of the present invention, the supporting means for supporting the leading end of the stacked sheets is provided below the separating means.

For this reason, even if the paper has lost its stiffness due to moisture absorption, the leading end is supported by the support means, so that the leading end of the paper does not go deeper. Therefore, when the leading edge of the paper penetrates deeper, the leading edge of the paper does not come off the corner claw,
It is possible to prevent the timing of detaching from the leading edge of the sheet from being delayed and causing a jam. Also, paper is not fed in a bent state.

According to the fourth aspect of the present invention, the front end of the supporting means is provided with an inclined surface for guiding the front end of the sheet to the separating means.

Therefore, when the leading end of the sheet comes into contact with the inclined surface, the sheet is guided toward the separating means, so that the sheet can easily pass over the separating means as compared with the third aspect of the invention.

[0016]

FIG. 1 shows an image forming apparatus 10 in which a sheet feeding device 12 according to a first embodiment is loaded.
Paper P fed from feeder 12 by feed roll 14
The toner image formed on the photosensitive drum 18 is transferred by being nipped and conveyed by the turn roll 16. The paper P to which the toner image has been transferred is heat-fixed by a fixing device 23 composed of a pressure roll 20 and a heating roll 22, and is discharged onto a tray from a paper discharge port 26 by a discharge roll 24.

On the other hand, as shown in FIG. 2, the substantially box-shaped sheet feeding device 12 is provided with a cassette 28 having an open top surface. A loading plate 30 on which the paper P is loaded is disposed at the bottom of the cassette 28. Pins 32 (see FIG. 1) are provided on both rear sides of the loading plate 30, and the loading plate 3 is provided.
Numeral 0 can swing about this pin 32.

Above the cassette 28, a rotating shaft 34 is rotatably supported by a bearing of a side plate (not shown). A pair of half-moon-shaped feed rolls 14 for feeding the paper P are fixed to the rotating shaft 34. This feed roll 14
Is larger than the frictional force generated between the paper P and the paper P.
Comes in contact with the sheet P, the sheet P is fed with the rotation of the feed roll 14.

A paddle 36 is fixed outside the feed roll 14. From the base of the paddle 36, thin transporting pieces 36A project radially at intervals of 90 degrees.

The transport piece 36A is formed of an elastic member, and is slightly longer than the radius of the feed roll 14. When the feed roll 14 contacts the sheet P and feeds the sheet P, as shown in FIG. 3, the paddle 36 contacts the sheet 36A with the sheet P, and the tip of the sheet 36A bends to transfer the sheet P. Convey while pressing.

Thus, not only the feed roll 14 but also
Since the paper P is also fed by the paddle 36, the paper P
And the traveling performance of the paper P is improved.

On the other hand, as shown in FIGS. 2 and 3, a substantially triangular corner claw 38 is provided at the tip corner of the cassette 28. The sheet P fed by the feed roll 14 and the paddle 36 has a corner claw 3 because the leading end of the sheet P is supported by the inner wall 28A of the cassette 28.
Between the rotating shaft 8 and the rotating shaft 34, the paper P rises upwards above the cassette 28.

For this reason, a restoring force is generated on the sheet P,
The tip corner of the paper P is disengaged from the corner claw 38, and the turn roll 16 is disposed upstream from the corner claw 38.
Is fed to the side.

The turn roll 16 includes a turn roll shaft 4 rotatably supported by a bearing of a side plate (not shown).
0, 42 are fixed. Further, a plurality of turn rolls 16 are fixed to reduce variations in the right and left sheet feeding force with respect to the sheet P. On the other hand, on the turn roll shaft 40, a leg portion 44A of a substantially rectangular weight bar 44 is rotatably supported. Therefore, weight bar 4
4, even if the turn roll shaft 40 rotates, the rotational force of the turn roll shaft 40 is not transmitted to the weight bar 44.

The leg 44A of the weight bar 44 is orthogonal to the turn roll shaft 40, and the length of the leg 44A is such that it reaches the leading end of the sheet P.

For this reason, the load portion 46 located at the leading end of the weight bar 44 holds down the leading end side of the paper P by its own weight, and as shown in FIG. Reduce. Further, since the weight bar 44 is rotatably supported by the turn roll shaft 40 (see FIG. 2), a constant load can always be applied to the leading end of the paper P. Also, the shaft 4 of the weight bar 44
The lift mechanism 4B is provided with a lift mechanism (not shown). When the cassette 28 is attached to and detached from the paper feeding device 12, the weight bar 44 is retracted so as not to be in the way.

Further, a trapezoidal non-contact portion 48 is formed at the center of the load portion 46 in the upward direction.
It is designed not to abut. The width of the non-contact portion 48 increases as it goes downward.

As a result, a force is applied to the non-contact portion 48 so as to spread outward, and the load portion 46 attempts to spread the sheet P from the center to the outside. And spread it out to give the paper a slight stiffness.

Further, the load portion 46 of the weight bar 44 is disposed near the corner claw 38. For this reason, the undulation of the paper P near the corner claw 38 is reliably pressed, and the stiffness of the paper P at the leading end portion of the paper P can be further increased, so that the paper P can surely climb over the corner claw 38. .

In order to dispose the load portion 46 near the corner claw 38, if it interferes with other components, a bent portion 50 is formed to secure the area of the load portion 46.

Next, the operation according to the first embodiment will be described.

As shown in FIG. 3, the paper P separated by the feed rolls 14 and the paddles 36 has the corners of the leading ends abutting against the corner claws 38. In this state, the feed rolls 14 and the paddles 36 feed the papers P. In order to make paper, the paper P rises upward.

At this time, as shown in FIG. 4, since the weight bar 44 presses the leading end side of the paper P, even if the surface of the paper P is wavy due to moisture absorption, the waving can be extended. The paper P can be stiffened. For this reason, even when the sheet of paper P has absorbed moisture, the leading edge of the sheet of paper P passes over the corner claw 38 and is fed.

The weight bar 44 does not necessarily need to be formed with the non-contact portion 48, but only needs to press the leading end of the sheet P, and therefore may have a simple rectangular shape. Further, the present invention is not limited to the weight bar 44, but may be any as long as it can press the leading end side of the paper P, and may be a band-like pressing piece. Further, the weight bar 44 may be supported on the rotating shaft 34.

Further, in this embodiment, the case where the corner claw 38 is used as the separating means has been described as an example, but the present invention is not limited to this.

Next, a paper feeder according to a second embodiment will be described.

Since the basic structure is the same as that of the sheet feeding device according to the first embodiment, only different portions will be described.

As shown in FIG. 5, a supporting portion 54 is formed below the corner claw 52 of the sheet feeding device 51. The support portion 54 is formed over the entire area inside the front end of the cassette 56 so that the front end portion of the sheet P comes into contact with the support portion 54. Therefore, even the moisture-absorbed paper P does not penetrate deep into the space between the inner wall 56A of the cassette 56 and the leading end of the paper P.

Further, an inclined surface 58 is formed in the support portion 54, and is inclined upward along the sheet P feeding direction. Therefore, the corner of the leading end of the sheet P abutting on the inclined surface 58 is guided to the corner claw 52 side.

Therefore, the feed roll 60 and the paddle 62
(See FIG. 6 respectively.) When the sheet P separated from the sheet P hits the inclined surface 58, the sheet P is guided to the corner claw 52 side along the inclination angle. The paper P does not get caught between the leading end of the paper P.

For this reason, there is no occurrence of a jam or a dog ear, and the paper P is fed in a state where the leading end of the paper P is bent, causing no skew or the like.

A gap Y is provided between the support portion 54 and the corner claw 52. When the sheet P is separated by the feed roll 60 and the paddle 62 by the gap Y, the leading end of the sheet P bends inward. Therefore, a restoring force is generated at the leading end of the sheet P, and the sheet P gets over the corner claw 52. It will be easier.

It is desirable that the support portion 54 is formed over the entire area inside the front end of the cassette 56, but it may be formed only below the corner claw 52.

Next, the operation of the sheet feeding device according to the second embodiment will be described.

As shown in FIG. 6, when the feed roll 60 and the paddle 62 try to feed paper, the leading edge of the sheet P already in contact with the inclined surface 58 is pressed by the corner claw 52. , The paper P rises upward. At this time, since the inclined surface 58 is guided to the corner claw 52 side, even if the paper P has absorbed moisture, the leading end does not penetrate deeper, and the paper P, which cannot maintain this state, is restored by the restoring force. Passes over the corner claw 52 and the paper P is fed to the turn roll 64 side.

In this embodiment, the case where the corner claw 52 is used as the separating means has been described as an example, but the present invention is not limited to this.

Although the sheet feeding device 12 according to the first embodiment and the sheet feeding device 51 according to the second embodiment are described as separate sheet feeding devices here, the sheet feeding device according to the first and second embodiments is described. They may be used simultaneously as a device.

[0048]

According to the present invention having the above-described structure, by providing the load means, even if the paper has no stiffness and has a wavy surface due to moisture absorption, the waving of the leading end of the paper can be suppressed.
Since stiffness is obtained at the leading end of the sheet as compared with the case without the load means, the sheet is fed over the separation means.
Also, since the leading end is supported by the supporting means, the leading end of the paper does not penetrate into the back, so that the leading corner of the paper does not come off the corner nail, and the leading corner of the paper comes from the corner nail. It is possible to prevent the paper from being fed in a state where the leading end of the paper is bent, as a result that the paper is prevented from being jammed due to the delayed release timing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an image forming apparatus using a sheet feeding device according to a first embodiment.

FIG. 2 is a perspective view illustrating a sheet feeding device according to a first embodiment.

FIG. 3 is a schematic side view showing the sheet feeding device according to the first embodiment.

FIG. 4 is a diagram illustrating a state in which a load unit provided in the sheet feeding device according to the first embodiment is pressing a sheet.

FIG. 5 is a schematic side view illustrating a support unit provided in a sheet feeding device according to a second embodiment.

FIG. 6 is a schematic side view illustrating a state where a sheet is fed by a sheet feeding device according to a second embodiment.

FIG. 7 is a perspective view showing a conventional sheet feeding device.

FIG. 8 is a diagram illustrating a case where a sheet absorbed by a conventional sheet feeding device is used.

FIG. 9 is a schematic side view illustrating a state in which a sheet that has absorbed moisture is being fed by a conventional sheet feeding device.

[Explanation of symbols]

 Reference Signs List 12 paper feeder 14 paper feed roll (paper feeder) 30 loading plate 36 paddle (paper feeder) 38 corner claw (separation means) 44 weight bar (loading means) 51 paper feeder 52 corner claw (separation means) 54 support Part (supporting means) 58 Inclined surface 60 Feeding roll (feeding means) 62 Paddle (feeding means)

Continued on the front page F term (reference) 3F343 FA02 FB02 FB04 FC01 GA03 GB01 GC01 GD01 HA14 HB03 HD18 JA09 JA19 JD03 JD11 JD35 LA04 LA15 LC07 LD03

Claims (4)

[Claims] A stacking plate on which sheets are stacked, and a sheet feeding means arranged above the stacking plate to feed the abutting sheet;
A separating unit provided on the leading end side of the stacking plate to separate the stacked sheets; and a load unit that presses a leading end of the sheet separated by the separating unit. Paper feeder. 2. The sheet feeding device according to claim 1, wherein said load means is provided near said separation means. 3. A stacking plate on which sheets are stacked, and a sheet feeding means arranged above the stacking plate to feed the abutting sheet,
A separating unit provided on the leading end side of the stacking plate to separate the stacked sheets, and a supporting unit provided below the separating unit and supporting the leading end of the stacked sheets. A sheet feeding device, comprising: 4. The sheet feeding device according to claim 3, wherein an inclined surface for guiding a leading end of the sheet to the separating unit is provided at a leading end of the supporting unit.