JPH081228Y2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sheet feeding device, and more particularly to a separation structure for copy sheets in an image forming apparatus such as a copying machine.

(Prior Art) As is well known, a sheet feeding device in an image forming apparatus such as a copying machine is provided with a structure for preventing double feeding of transfer sheets to be fed, as shown in FIG. There is something.

That is, the sheet feeding device shown in FIG. 4 is located, for example, on the upstream side of the transfer portion B in the rotating direction of the drum-shaped photosensitive member A (the direction of the arrow in the figure), and the structure thereof is the transfer sheet S. A sheet feeding table C in which the sheets are stored and housed, a feeding roller D located above the sheet feeding cassette C and rotatable in the feeding direction of the transfer sheet S, and a feeding sheet S from the sheet feeding table C. Direction (the direction of the arrow in the figure), the paper feed roller E located downstream of the paper feed roller D and rotatable in the same direction as the paper feed roller D, the friction pad F facing the paper feed roller E and the friction thereof. A spring G that presses and urges the pad F toward the paper feed roller E.
And a registration roller pair H located downstream of the paper feed roller E in the feeding direction of the transfer sheet S and for synchronizing the leading edge of the image on the photoconductor A with the leading edge of the transfer sheet S. is there. The friction pad F described above is
In place of the pad-like member shown in the drawing, a roller-like member which covers the entire circumference in the axial direction with a friction member and is capable of coming into contact with and separating from the paper feed roller E may be used, though not shown.

In the above-described sheet feeding device, for example, the transfer sheet S fed from the sheet feeding table C by the feeding roller D is used.
When a plurality of sheets of paper are fed in a state of being overlapped with each other, and when the leading end of the sheet is sandwiched between the paper feed roller E and the friction pad F, the transfer paper is brought into contact with the paper feed roller E and the friction pad F. The transfer sheet in contact with the friction pad F is prevented from advancing due to the difference in the friction coefficient between the pair of registration rollers H in a single state in which double feeding is blocked. It is designed to be transported to.

By the way, in the above-mentioned structure for preventing the double feeding of the transfer paper, conventionally, as the structure of the paper feed roller E, in the case of the thin paper, the surface shape of a saw blade is set as shown in FIG. Although not shown, the roller is made of foamed rubber having a large number of fine holes on its surface, or
In the case where plain paper or the like is conveyed at a relatively low speed, there is one in which the roller is made of silicon rubber whose surface is roughly polished.

(Problems to be Solved by the Invention) However, in the above-described paper feed roller E, for example, when it has a saw blade-shaped surface, as shown in FIG. The leading edge of the transfer sheet S conveyed from the sheet feeding table C may enter into a certain groove E2, and the leading edge may be rotated along with the rotation of the sheet feeding roller E, whereby the sheet is fed from the feeding roller D. The leading end (the center of the sheet) of the transfer sheet S is stopped by the sheet feed roller E. However, since the left and right sides of the paper are free, the leading edge of the paper is not straight. That is, the center of the sheet is slightly less fed out than the left and right sides, and as a result, the leading edge of the sheet is wavy.

When the transfer sheet S in such a state is held by the registration roller H, the leading edge of the sheet may not be held evenly in the nip portion of the registration roller in the axial direction.
When it is conveyed by the registration roller H and pressure is applied by the roller B of the transfer section in a state where the pinched state is not completely corrected, wrinkles or wrinkles are formed in the corrugated portion, and a copy is obtained. Quality will be impaired.

Further, when the phenomenon that the leading end of the transfer paper S enters the groove of the saw blade occurs in the case of thick paper such as drawing paper, the pressure bias to the leading end due to the trailing end feeding of the paper becomes large. In addition to being unable to be fed out, there is a possibility that the surface of the paper may be peeled off due to the sliding friction between the groove wall surface and the leading end of the paper.

Further, in the case of the above-mentioned saw blade-shaped paper feeding roller, when the top of the blade E1 is in a position where it coincides with the direction of the normal to the friction pad, and when the position is equally divided across this normal. The distance from the center of the paper feed roller E to the contact position between the blade E1 and the friction pad F is different from that when the top of the blade is located at, that is, in other words, The contact position between the friction pad F and the blade E1 of the paper feed roller E is L
It changes as shown in.

Therefore, when the contact position on the friction pad F side is changed in this way, for example, when the contact position on the friction pad F side is displaced to the center side of the paper feed roller E, the extension amount of the spring G pressing the friction pad F is increased. It will change to a larger state, and as a result,
By reducing the pressing force using the spring G, the paper feeding roller E
Separation utilizing the difference in friction coefficient between the transfer sheet S and the transfer sheet S, between the transfer sheets S, and between the transfer sheet S and the friction pad F may not function effectively.

Therefore, in order to solve this problem, it has been conventionally considered to assemble the roller by shifting the phase of the saw blade located on the surface of the paper feed roller, but if such a procedure is adopted, the assembly cost is reduced. There is a new problem of rising.

Further, when the paper feed roller E is a foam rubber roller or a silicone rubber roller, since the roller outer shape is cylindrical,
Although excellent in the function of guiding the leading edge of the sheet to the nip portion with the friction pad, the surface is worn due to contact with the transfer sheet, and when the transfer sheet S is conveyed,
In some cases, the rollers slip and the paper cannot be fed well.

Therefore, in view of the above-mentioned problems in the conventional transfer paper feeding structure, an object of the present invention is to perform good paper feeding regardless of the paper thickness and to maintain the quality of a copy without damaging the transportation state. To obtain a sheet feeding device that does not lower the feed rate.

(Means for Solving the Problem) In order to achieve this object, the present invention provides a feeding roller that rotates in a feeding direction of the paper from a paper feeding unit that accommodates the paper, and a feeding roller that feeds the paper. Rotatable paper feed roller that abuts the upper surface of the paper,
The paper feed roller is provided with a friction member facing the paper feed roller, and a means for biasing the friction member toward the paper feed roller to press the paper feed roller when the fed paper is double fed. In the paper feeding device for feeding the multi-fed paper in a separated state by utilizing the difference in friction coefficient between the roller and the paper, between the paper, and between the paper and the friction member, the paper feeding roller is , One or a plurality of cylindrical rubber rollers having a cylindrical shape over the entire circumference, and one or a plurality of saw blade-shaped rubber rollers which are separate from the cylindrical rubber roller and whose outer diameter is substantially the same as that of the cylindrical rubber roller in the axial direction. The feature is that they are arranged in contact with each other alternately.

(Operation) In the present invention, when the paper feed roller is pressed against the separation roller, the cylindrical portion and the saw blade portion of the paper feed roller can be independently deformed at the boundary between these portions on the contact surface.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a model view of a sheet feeding device according to an embodiment of the present invention, which is equivalent to FIG.

The feature of the present embodiment is that a saw blade having a slightly larger outer diameter is such that a part thereof is a cylindrical rubber roller in the axial direction of the paper feed roller, and the other portion is in a category of substantially the same diameter as the outer diameter of the rubber roller. A rubber roller is used, and a transfer paper guide mechanism is added to the cylindrical rubber roller.

That is, the sheet feeding roller 1 can be interlocked with the feeding roller 3 located above the sheet feeding table 2 by, for example, the belt 4, and the rotation direction thereof is the direction in which the transfer sheet 5 can be fed. .

On the other hand, the above-mentioned paper feed roller 1 is a cylindrical roller 1A made of foam rubber and a body separate from the cylindrical rubber roller 1A. The outer diameter of the roller 1A is substantially the same as that of the cylindrical rubber roller 1A, and the surface of the roller is saw blade. It is configured by combining with a saw blade-shaped rubber roller 1B formed into a shape, and each of these rollers 1A and 1B has a cylindrical rubber roller 1A at the center in the axial direction as shown in FIG.
, And the saw blade rubber rollers 1B are arranged on both sides thereof.

Both rollers described above are fixed to a common drum-shaped core metal 6 and can be independently deformed at the contact surface of the paper. The core metal 6 is a support shaft 7 (see FIG. 3).
The core metal 6 is provided with a one-way clutch (not shown), and the one-way clutch supports the transfer paper 5 only when the transfer paper 5 is conveyed to the registration rollers. It is designed to transmit rotation in the feeding direction.

The saw blade rubber roller 1B described above has a slightly larger outer diameter than the cylindrical rubber roller 1A as shown in FIG. 2, and the top portion 1B1 of the saw blade slightly projects from the circumferential surface of the cylindrical rubber roller. ing.

The protrusion amount of the saw blade top portion 1B1 is such that the leading end of the transfer sheet 5 is prevented from entering the groove between the blade tip portions 1B1 and the leading end of the transfer sheet 5 which is prevented from entering is separated by a separation roller described later. It is said that the amount can be guided to the side.

On the other hand, the separation roller 9 provided at one end of the pressure arm 8A, which is provided with the habit of rotating counterclockwise in FIG. A friction member having a smaller friction coefficient than the friction coefficient on the surface of the paper feed roller 1 is fixed to the peripheral surface of the separation roller 9. In FIG. 1, reference numeral 10 indicates a registration roller having the same function as that shown in FIG.

Since the present embodiment has the above-described structure, the transfer sheet 5 is now transferred from the sheet feeding table 2 by the feeding roller 3.
When the transfer sheet 5 is fed between the sheet feeding roller 1 and the separation roller 9, the feeding roller 3
The paper feed roller 1 also rotates in a direction in which the feeding direction of the transfer paper 5 can be set through the one-way clutch in conjunction with the rotation of the.

On the other hand, as shown in FIG. 2, when the fed transfer paper 5 is double-fed, the transfer paper 5 at the uppermost position is transferred.
Corresponds to the tip of the cylindrical rubber roller 1A by the top 1B1 of the saw blade rubber roller 1B facing the blade top 1B1 according to the rotation of the paper feed roller 1 and between the blade tops 1B1 of the cylindrical rubber roller 1A. The peripheral surfaces are pushed toward the peripheral surface of the separation roller 9 to prevent the fluttering of the tip, and are sandwiched between the peripheral surface of the separation roller 9 and the peripheral surface.

Therefore, the transfer sheet 5 has a coefficient of friction between the separation roller 9 and the transfer sheet 5, a coefficient of friction between the transfer sheets 5 and a difference in coefficient of friction between the saw blade rubber roller 1B and the transfer sheet 5. In this case, the transfer sheet 5 on the side of the separation roller 9 provided with a friction member on the peripheral surface is prevented from advancing, and only the transfer sheet 5 on the side of the sheet feed roller 1 is fed in a single state to be the registration roller. Delivered for 10. Moreover, since the cylindrical rubber roller 1A and the saw blade-shaped rubber roller 1B can be independently deformed on the contact surface of the paper, the saw blade-shaped rubber roller 1B covers the entire area in the axial direction including the boundary with the cylindrical rubber roller 1A. Since a uniform gripping force is applied to the paper throughout, it is possible to efficiently apply a frictional force for separating and conveying the paper.

According to the present embodiment, the outer diameter of the saw-toothed rubber roller 1B is slightly increased within a range that can be said to be substantially the same as the outer diameter of the cylindrical rubber roller 1A, and the cylindrical rubber roller 1A is separated from the separation roller 9 and the saw-toothed rubber roller 1B. Since it can function as a guide member for holding the transfer sheet 5 between the transfer roller and the transfer sheet, abrasion can be suppressed as compared with the case where the cylindrical rubber roller 1A is constantly in contact with the transfer sheet. In addition, it is possible to prevent the transport capacity from being lowered.

The arrangement configuration of the cylindrical rubber roller 1A and the saw blade rubber roller 1B described above is not limited to the example shown in FIG. 3, and the cylindrical rubber roller 1A may be located on both sides of the saw blade rubber roller 1B. Of course.

The relationship between the outer diameters of the cylindrical rubber roller 1A and the saw blade-shaped rubber roller 1B in the paper feeding roller depends on the guide of the transfer sheet 5 by the cylindrical rubber roller and the saw-shaped blade rubber roller.
It is needless to say that the present invention is not limited to the above-mentioned examples in the category of substantially the same diameter as long as a relationship can be obtained in which the function of filling the groove between the blade tips in 1B, that is, the space is achieved.

(Effect of the Invention) As described above, according to the present invention, a part of the axial direction is formed by a cylindrical rubber roller, and the other part has a saw-toothed shape whose outer diameter is different from the outer diameter of the rubber roller. By configuring the paper feed roller as the rubber roller of the paper, it is possible to prevent the paper from entering the groove located between the blades of the saw blade-shaped rubber roller. It is possible to prevent flapping and to prevent wrinkles and wrinkles from occurring and to prevent the quality of the copy from being impaired.

In addition, when feeding the paper, the groove space located between the blade tips of the saw blade rubber roller is filled with a cylindrical rubber roller, and the saw blade rubber roller has a cylindrical shape on the contact surface of the paper. Since it can be deformed independently of the rubber roller, uniform contact can be made in the entire axial direction including the boundary with the cylindrical rubber roller, regardless of the position between the blade tips of the saw blade rubber roller with respect to the friction member, In addition, the clamping pressure between the saw blade-shaped rubber roller and the friction member in the axial direction can be made substantially uniform, and the sheets can be satisfactorily separated due to the difference in friction coefficient.

[Brief description of drawings]

FIG. 1 is a model diagram for explaining the main part of the sheet feeding device according to the embodiment of the present invention, FIG. 2 is a partially enlarged view of the main part shown in FIG. 1, and FIG. 3 is FIG. FIG. 4 is a model view for explaining a conventional paper feeding device, and FIG. 5 is a main part of the paper feeding device shown in FIG. 4 in the direction of the arrow III-III. 1 is a model diagram corresponding to FIG. 1, FIG. 6 is a partially enlarged view of the main part shown in FIG. 5, and FIG. 7 is a partially enlarged view for explaining the operation of the structure shown in FIG. is there. 1 ... Paper feeding roller, 1A ... Cylindrical rubber roller, 1B ... Saw blade rubber roller, 1B1 ... Blade top, 2 ... Paper feeding table, 3 ... Feeding roller, 5 ... Transfer paper, 7 ... Support shaft, 9 ... Pressure roller having a friction member.

Claims (1)

[Scope of utility model registration request] 1. A feeding roller that rotates in a feeding direction of the paper from a paper feeding section that accommodates the paper, and a rotatable feeding roller that abuts an upper surface of the paper fed by the feeding roller. The paper feed roller is provided with a friction member facing the paper feed roller, and a means for biasing the friction member toward the paper feed roller to press the paper feed roller when the fed paper is double fed. In a paper feeding device for feeding multi-fed paper in a separated state by utilizing the difference in friction coefficient between the roller and the paper, between the paper, and between the paper and the friction member, the paper feed roller is , One or a plurality of cylindrical rubber rollers having a cylindrical shape over the entire circumference, and one or a plurality of saw blade-shaped rubber rollers which are separate from the cylindrical rubber roller and whose outer diameter is substantially the same as that of the cylindrical rubber roller in the axial direction. Alternate contact along A paper feeder characterized by being placed in contact with each other.