JPH08198472A - Medium delivering mechanism - Google Patents

Abstract

PURPOSE: To securely deliver a medium at a high degree of surface smoothness by projecting a medium guide toward the center of the rotation of a feed roller in both sides of the feed roller, and increasing the medium carrying force of the feed roller in proportion to the reaction force by the curve of the medium. CONSTITUTION: When a feed roller 4 is rotated in the direction A, one piece of the cutform papers, which are 2 loaded on a cassette 1, positioned at the top is delivered for output between a separator 6 and the feed roller 4. When the cutform paper 2 of the top position is delivered to a medium guide 7, since the medium guide 7 is projected toward the center of the rotation of the feed roller by the predetermined quantity X, a corresponding part of the cutform paper 2 is curved by the predetermined quantity X. On the other hand, a part, to which the work of the medium guide 7 is not applied and which contacts with the medium contact surface 4 of the feed roller 4, is pushed to the feed roller 4 by the reaction force of the cutform paper 2. As a result, the new frictional force is generated between the feed roller 4 and the cutform paper 2, and the medium carrying force of the feed roller 4 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium feeding mechanism for feeding a medium from a cassette and feeding it into an apparatus.

[0002]

2. Description of the Related Art Conventionally, in a recording apparatus such as an electrophotographic recording apparatus, when a cut sheet as a medium loaded in a cassette is reversed and then fed out to a medium conveying path, first, a feeder roller is used. One sheet of cut paper is fed from the cassette by rotation. Then, the single-cut sheet is conveyed between the separator and the feeder, which is provided near the circumference of the feeder and is urged to the feeder by the urging means, and the separator is fed. Presses the cut sheet against the feeder.

When the cut sheet is further fed, the cut sheet is fed to a paper guide provided downstream of the separator in the medium feeding direction, and the leading end of the cut sheet is fed around the feeder roller by the paper guide. It is directed to an inversion guide provided by the side. Then, when it is fed to the reversing guide, the front end portion is conveyed along the reversing guide, and the cut sheet is reversed there and is fed to the medium conveying path.

Note that the cut sheet is conveyed by the friction force between the feeder and the cut sheet when the cut sheet is fed out from the cassette, and the cut sheet is fed by a separator.
It is carried out by two frictional forces, namely, a frictional force generated by being pressed against the lathe and generated between the feeder roller and the cut sheet.

Regarding the frictional force in the separator, the friction coefficient between the feeder and the cut sheet is "μ".
1 ", the friction coefficient between the highest cut sheet and the second cut sheet fed together with the highest cut sheet is" μ2 ",
The friction coefficient between the separator and the second cut sheet is "μ3"
Then, the following Expression 1 is established between “μ1”, “μ2”, and “μ3”.

.Mu.1>.mu.3> .mu.2 (1) Since the above formula 1 is satisfied, a conveying force for the cut sheet is generated in the separator section.

[0007]

In the above-mentioned conventional medium feeding mechanism, when a strong single-cut sheet is tried to be fed to the medium transport path, the leading end of the single-cut sheet is fed to the reversing guide, and When the leading edge contacts the reversing guide, a load is applied to the leading edge of the cut sheet, and the conveyance of the leading edge of the cut sheet may stop there.

Even if the leading end of the cut sheet is stopped, the cut sheet continues to be fed by the feeder, so that the portion corresponding to the separator of the cut sheet is separated. It swells greatly against the urging force from the ta. Then, the bulging portion is separated from the feeder, so that the contact pressure between the feeder and the cut sheet is reduced accordingly.
The medium conveying force of the feeder in the separator part is extremely reduced.

Then, the frictional force for conveying the single-cut sheet is only the frictional force between the feeder and the single-cut sheet when the single-cut sheet is fed out from the cassette, and the frictional force of the feeder is reduced. The medium conveying force is extremely reduced, and slippage occurs between the feeder and the cut sheet. As a result, there is a problem in that the cut sheet cannot be fed to the medium running path.

On the other hand, when a cut sheet having a smooth surface, that is, a high surface smoothness is to be fed to the medium conveying path, the friction force between the feeder and the cut sheet when the cut sheet is fed from the cassette. Since the single-cut sheet is pressed against the feeder by the separator, the frictional force generated between the feeder and the single-cut sheet is small.
There is a problem that slippage occurs between the drawer and the cut sheet, and the cut sheet cannot be fed out.

In order to solve the above-mentioned problems, an auxiliary roller which is pressed against the feeder roller with a constant pressing force and rotates together with the feeder roller is provided, and a single-cut sheet is fed by the feeder roller. There is a means for pushing the medium to enhance the medium conveying force of the feeder.

However, since the auxiliary roller, the biasing means for applying a pressing force to the auxiliary roller and maintaining the state, and the tool for attaching them are required, the mechanism becomes complicated, As a result, there is a problem that the cost becomes high.

[0013]

In order to solve the above-mentioned problems, a solution means provided by the present invention is to feed a medium loaded in a cassette by a feeder and feed the fed medium by a separator. -In a medium feeding mechanism that pushes against a drawer and guides the medium to a reversing guide by a medium guide to invert the medium and then feeds it to a medium traveling path, the medium guides are fed on both sides of the feeder. The protrusion is made toward the rotation center direction of the la.

[0014]

The medium is fed out from the cassette by the rotation of the feeder. Then, the medium is pressed against the feeder roller by the separator, guided by the paper guide, and the leading end portion is directed to the reverse guide. At this time,
Since the medium guide projects toward the direction of the center of rotation of the feeder, the medium is curved by the amount of the projecting guide except for the portion corresponding to the feeder. Then, the part corresponding to the feeder of the medium is
The reaction force of the medium causes the medium to be pressed against the feeder, so that a frictional force is newly generated between the feeder and the medium, and the medium conveying force of the feeder increases.

Therefore, even if the medium has a high surface smoothness, no slippage occurs between the feeder and the medium.

Further, since a medium having a high rigidity is also pressed against the feeder, the medium conveying force of the feeder is increased.

Then, the leading end of the stiff medium reaches the reversing guide and abuts against the reversing guide, and the load reduces the medium conveying force of the feeder, resulting in a medium separator. Even if the corresponding portion tries to swell, the protrusion of the medium guide suppresses the force of the medium trying to swell, so that the medium does not swell.

Therefore, the contact pressure between the feeder and the medium does not decrease due to the increase of the medium conveying force of the feeder and the prevention of the swelling of the medium by the medium guide. No slippage occurs with the medium.

[0019]

Embodiments of the present invention will be described with reference to the drawings. The elements common to the drawings are designated by the same reference numerals. FIG. 1 is an explanatory view showing the structure of a medium feeding mechanism of an embodiment according to the present invention, and FIG. 2 is an explanatory diagram showing a medium feeding mechanism of the embodiment. 2 is a view of FIG. 1 viewed from the direction of arrow B, and the reversing guide 8 is omitted.

In FIG. 1 and FIG. 2, a cut sheet 2 as a medium loaded in a cassette 1 is provided on a medium running path (not shown) provided in an electrophotographic recording apparatus which is a recording apparatus, and a medium feeding mechanism 3 is provided. Will be delivered one by one.

A sheet stacking plate 10 is provided inside the cassette 1 in a state of being urged in the direction of the feeder roller 4 by a push spring 9, and the sheet stacking plate 10 is provided on the sheet stacking plate 10.
Is loaded.

Single-cut sheets 2 loaded in the cassette 1
Is a feed roller 4 attached to a shaft 5 provided in the electrophotographic recording apparatus by the urging force of a push spring 9.
It is pressed against and is driven by the drive source.
Only the uppermost cut sheet 2 is separated by the rotation of the la 4, and is fed out in the medium running path direction of the electrophotographic recording apparatus.

A feeder 4 near the cassette 1
The peripheral surface is provided with a separator 6 which is pressed against the feeder roller 4 by a biasing means (not shown). By this separator 6, a plurality of single-cut sheets 2 are fed into the cassette 1.
From being fed to the medium traveling path.

A plurality of medium guides 7 are provided downstream of the separator 6 in the medium feeding direction and on both sides of the feeder roller 4. The medium guides 7 allow the cut sheet 2 to be cut.
The tip of the guide is guided by a reversing guide 8 described later. As shown in FIG. 2, the medium guide 7 projects from the medium contact surface 4a of the feeder roller 4 toward the center of rotation of the feeder roller 4.

A reversing guide 8 for reversing the single-cut sheet 2 is provided downstream of the medium guide 7 in the medium feeding direction and near the periphery of the feeder roller 4. A medium running path (not shown) is located further downstream of the reversing guide 8 in the medium feeding direction.

A feeder 4 and a separator 6 are provided.
The medium guide 7 and the reversing guide 8 constitute the medium feeding mechanism 3.

If, for example, the distance from the center of rotation of the feeder roller 4 to the reversing guide 8 is 22 mm and the diameter of the feeder roller 4 is 36 mm, then the feeder roller 4 of the medium guide 7 will have a diameter of 36 mm. The amount of protrusion from the medium contact surface 4a toward the direction of the center of rotation of the feeder roller 4 is X, and the distance from the side surface 4b of the feeder roller 4 to the side surface 4b of the feeder roller is closest to the side surface 4b. Assuming that the distance to the medium guide 7 is Y, the optimum value is to set the values of X and Y by the ratio shown in the following mathematical formula 2.

Y / X = 40/1 (2) Next, the medium feeding operation in the above configuration will be described. In FIG. 1, when the feeder roller 4 starts to rotate in the direction of arrow A, the uppermost one sheet or several upper sheets of the cut sheets 2 stacked in the cassette 1 are fed from the cassette 1.
It is fed out between the drawer 4 and the separator 6. The separator 6 is fed with a constant pressing force by a biasing means (not shown).
Since it is pressed against the drawer 4, further frictional force is generated between the feeder 4 and the uppermost cut sheet 2, and as a result, the uppermost sheet fed out together with the uppermost sheet is fed. The single-cut sheet 2 is no longer fed downstream in the medium feeding direction.

When the uppermost cut sheet 2 is fed to the medium guide 7, as shown in FIG. 2, the medium guide 7 has a shape protruding toward the center of rotation of the feeder roller 4. Therefore, the portion of the cut sheet 2 corresponding to the medium guide 7 is curved by the amount of X. Since the medium guides 7 are provided on both sides of the feeder roller 4, there is no action of the medium guides 7 and the portion of the cut sheet paper 2 in contact with the medium contact surface 4a of the feeder roller 4 is not affected. The reaction force of the single-cut sheet 2 is pressed against the feeder roller 4.
As a result, a frictional force is newly generated between the feeder roller 4 and the cut sheet 2, and the medium conveying force of the feeder roller 4 increases.

When the cut sheet 2 is further fed from the cassette 1, it is guided by the medium guide 7 and the leading end thereof is guided by the reversing guide 8. Here, the leading end of the cut sheet 2 is conveyed by the medium conveying force of the feeder 4 while contacting the reversing guide 8. Here, if the cut sheet 2 is stiff, the cut sheet 2 is conveyed. A load is applied to the leading end of sheet 2 in the direction of arrow C, and the transportation of the leading end of cut sheet 2 is likely to stop there.

When the leading edge of the cut sheet 2 is about to be stopped, the feeder 4 continues to convey the cut sheet 2, so that the portion of the cut sheet 2 corresponding to the separator 6 is conveyed. Tries to inflate. However, the portion of the cut-sheet paper 2 that is in contact with the medium contact surface 4a of the feeder 4 is pressed against the feeder 4 by the medium guide 7, so that The medium feeding force is strong. Therefore, the feeder 4 can feed the cut sheet 2 to the medium running path by overcoming the load applied to the leading end of the cut sheet 2. Further, even if the portion of the cut-sheet paper 2 corresponding to the separator 6 swells, the cut-out sheet 2 is prevented from swelling because it is pressed by the medium guide 7. Due to the two functions of the medium guide 7,
Since the reduction of the contact pressure of the cut sheet 2 with the feeder 4 is prevented, the medium conveying force of the feeder 4 near the separator 6 does not decrease.

Therefore, the cut sheet 2 is rubbed by the feeder 4 and the cut sheet 2 when the cut sheet 2 is fed from the cassette 1, and the cut sheet 2 is separated by the separator 6. Since it is pressed against the feeder roller 4 and is conveyed by the frictional force generated at two points, that is, the frictional force generated between the feeder roller 4 and the cut sheet 2, Even the form sheet 2 can be fed to the medium traveling path.

On the other hand, even when the cut sheet 2 having a small friction coefficient, that is, a high surface smoothness is fed to the medium running path, the medium guide 7 allows the medium of the feeder 4 of the cut sheet 2 to be fed. The part in contact with the contact surface 4a is pressed against the feeder 4 by the reaction force of the cut sheet 2, and between the newly generated feeder 4 and the cut sheet 2. Since the medium conveying force of the feeder roller 4 is increased by the frictional force, the slippage does not occur between the feeder roller 4 and the cut sheet 2. As a result, even the cut-sheet paper 2 having a high surface smoothness can be fed to the medium traveling path.

Further, by providing the medium guide 7 over the entire width of the cut-sheet paper 2, it is possible to further enhance the medium-conveying force of the feeder 4 for the cut-sheet paper 2 having a strong rigidity.

..

Since the present invention is configured as described above, it has the following effects. By making the medium guide project toward the center of rotation of the feeder on both sides of the feeder, the medium conveying force of the feeder is proportional to the reaction force due to the bending of the medium. Increase. Therefore, the slip between the feeder and the medium can be prevented, so that even a medium having a high surface smoothness can be fed to the medium traveling path.

On the other hand, the load between the reversing guide and the leading end of the medium increases in proportion to the stiffness of the medium, but the contact pressure between the feeder and the medium increases, so the feeder
The transport force of la becomes large. As a result, the loader is able to overcome the load and transport the media.

Further, even if the medium tries to swell due to the load of the reversing guide and the tip of the medium, the medium guide presses the medium, so that the separator is not separated from the feeder. Therefore, by preventing the medium from swelling by the medium guide and increasing the feeding force of the feeder, even a medium having a strong stiffness can be fed to the medium traveling path.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a structure of a medium feeding mechanism according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a structure of a medium feeding mechanism according to an embodiment.

[Explanation of symbols]

 1 cassette 2 single-cut sheet 3 medium feeding mechanism 4 feeder roller 6 separator 7 medium guide

Claims (2)

[Claims] 1. A medium loaded in a cassette is fed out by a feeder, the fed medium is pressed against the feeder by a separator, and a medium guide guides the medium to an inversion guide to invert it. In the medium feeding mechanism that feeds the medium to the medium running path after the above, the medium guiding mechanism projects the medium guides on both sides of the feeder in the direction of the center of rotation of the feeder. 2. The medium feeding mechanism according to claim 1, wherein the medium guide is projected toward the center of rotation of the feeder on both sides of the feeder, over the entire width of the feeder.