JPH05310331A - Sheet feeding roller for sheet feeding device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a sheet feeding device with stable feeding performance. [Structure] By rotating the paper feed roller in contact with the uppermost sheet of the cassette, frictional force is applied to the uppermost sheet, and the separating pad applies a braking force due to friction from the back surface of the sheet other than the uppermost sheet. In a sheet feeding device that feeds only one of the uppermost sheets, the paper feeding roller is a half-moon shaped rubber roller 2a fixed to a rotary shaft 2d, and both ends of the half-moon shaped rubber roller 2a which are freely rotatable on the rotary shaft 2d. The half-moon shaped rubber roller 2a is composed of an outer peripheral portion 2p that comes into contact with the uppermost sheet and a recessed portion 2z in which a part of the outer peripheral portion 2p is cut off. By providing the protrusion 2f having a diameter of the outermost circumference smaller than the diameter of the abutting roller 2b in the depression 2z, stable feeding performance without double feeding is realized. It

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder for separating and feeding a plurality of sheets such as paper or film laminated one by one.

[0002]

2. Description of the Related Art A copying machine or a printer is equipped with a sheet feeding device for separating and feeding a plurality of stacked sheets one by one. Copiers and printers usually use paper, but sometimes transparent films are also used, so these are collectively called sheets.

First, a printer equipped with a conventional sheet feeding apparatus will be described.

FIG. 10 is a sectional view of the printer. Reference numeral 1 denotes a printer main body, and the inside thereof includes a sheet feeding device described later and the following devices. The surface of the recording medium 12 is charged by the charging device 11, and the exposure device 13 irradiates optical information to form an electrostatic latent image. A developing device 14 supplies a developer to the surface of the recording body 12 to visualize the electrostatic latent image. On the other hand, the sheet 4c is conveyed from the laminated sheet 4 by the paper feed roller 2 and the conveying roller 7 so as to be in close contact with the surface of the recording body 12, and the visible image on the recording body 12 is transferred onto the sheet 4c by the transfer device 17. Transcribed. Reference numeral 18 denotes a fixing device that fixes the visible image on the sheet to the sheet.
Is discharged to the outside of the printer. 20 is a recording body 12
This is a cleaning device for removing the developer still remaining on the recording body 12 after the above visible image is transferred onto the sheet. The apparatus group described above will be collectively referred to as an image forming apparatus hereinafter.

Next, a conventional sheet feeding device will be described. The sheet feeding device includes a cassette 8 for setting the stacked sheets 4 in the printer body 1, a paper feed roller 2 arranged at the tip of the cassette 8, and a separation pad 3 arranged to face the paper feed roller 2. , Separating pad 3 and laminated sheet 4
Is composed of pressing springs 5 and 6 that press the sheet feeding roller 2 against the sheet feeding roller 2. Paper feed roller 2 is usually the top sheet 4
Only a is sent out, but sometimes a plurality of sheets are sent out. When a plurality of sheets are fed out in this way, the separation pad 3 serves to prevent the sheets other than the uppermost sheet 4a from being braked by friction from the back surface.

Next, the structure of the paper feed roller 2 and the sorting pad 3 will be described. FIG. 11 is a perspective view of the sheet feed roller and the separation pad 3 of the conventional sheet feeding apparatus, and FIG. 12 is a cross-sectional view of the sheet feed roller 2 in the conventional example. As shown in the figure, the paper feed roller 2 includes a core portion 2c fixed to a rotary shaft 2d.
And a half-moon shaped rubber roller 2a formed around the core portion 2c, and abutting rollers 2b arranged on both ends of the half-moon shaped rubber roller 2a coaxially with the rotary shaft 2d and rotatable with respect to the rotary shaft. It

As is apparent from FIG. 12, the half-moon shaped rubber roller 2a has a recessed portion 2z whose outer periphery is cut off by an angle α, and the outer peripheral portion 2 is formed only by the angle β shown in FIG.
There is no p left. When the half-moon shaped rubber roller 2a rotates in the direction of arrow A along with the rotation of the rotary shaft 2d, the tip 2x of the outer peripheral portion 2p of the half-moon shaped rubber roller 2a is laminated sheet 4.
Of the outermost part of the outer peripheral portion 2p and ends at the rear end 2y of the outer peripheral portion 2p. Of course, the relationship between the angle α and the angle β is β = 360 degrees−α.

When the rotating shaft 2d rotates, the half-moon shaped rubber roller 2a rotates together with the rotating shaft 2d, but the abutting roller 2b.
Does not rotate because it is free to rotate with respect to the rotating shaft 2d. Further, as shown in FIG. 12, the outer diameter D1 of the abutting roller 2b is
It is configured to be smaller than the outer diameter C1 of the half-moon shaped rubber roller 2a. When the separating pad 3 is pressed in the direction of the sheet feeding roller 2 by the pressing spring 5, the separating pad 3 recesses the outer peripheral portion 2p of the half-moon shaped rubber roller 2a, and the outer peripheral portions of the separation pad 3 and the half-moon shaped rubber roller 2a. Although a pressing force is generated between the loose pad 3 and the half-moon rubber roller 2a, when the loose pad 3 hits the abutting roller 2b, the outer peripheral portion 2p of the half-moon rubber roller 2a does not recess further. The pressing force with the outer peripheral portion 2p is regulated so as to be constant.

The operation of the conventional seat device configured as described above will be described below.

(1) The state shown in FIG. 10 is the standby state of the sheet feeding device. In this state, the recessed portion 2z of the half-moon shaped rubber roller 2a of the sheet feeding roller 2 faces the laminated sheet 4. Further, as described above, the separating pad 3 is in contact with the abutting roller 2b, but the half-moon shaped rubber roller 2
Since it faces the depressed portion 2z of a, it does not contact the outer peripheral portion 2p of the half-moon shaped rubber roller 2a.

(2) When an image is formed on the recording medium 12 by the image forming apparatus described above, a control unit (not shown) outputs a sheet feeding command for feeding the uppermost sheet of the laminated sheet 4.

(3) The paper feed roller 2 according to the above paper feed command.
Rotates once in the direction of arrow A and returns to the original standby state again. During this one-rotation operation, the uppermost sheet 4a of the laminated sheet 4 is sent out, conveyed to the conveying roller 7, and stands by once. After that, the sheet is sent out from the transport roller 7 at a timing such that the leading edge position of the image on the recording body 12 and the leading edge position of the sheet match.

[0013]

However, the above-mentioned conventional sheet feeding apparatus has a high probability of so-called "double feeding" in which two or more sheets are stacked and fed to the conveying roller 7. The process when “double feed” occurs will be described below. 13A and FIG.
FIG. 7B is an explanatory diagram when a double feed occurs.

As described above, when the sheet feeding command is issued, the half-moon shaped rubber roller 2a starts to rotate in the direction of arrow A, as shown in FIG.
As shown in, the tip 2x of the outer peripheral portion 2p of the half-moon shaped rubber roller 2a first contacts the uppermost sheet 4a of the laminated sheet 4. The contact position at this time is a position slightly rearward from the front end of the uppermost sheet 4a. And half-moon shaped rubber roller 2a
The sheet is sent out by the frictional force between the sheet and the sheet. At this time, there is no problem if the half-moon shaped rubber roller 2a sends out only one of the uppermost sheets 4a in FIG. 13 (a). However, if two or more sheets are sent out as shown by 4a and 4b, the trigger of double feeding occurs. become. Originally, even if two or more sheets are sent out, as described above, the sheets 4b other than the uppermost sheet 4a are braked from the back surface by the separating pad 3, so that only the uppermost sheet 4a should be sent out as a result. However, as described above, the recessed portion 2z is formed between the front end 2x of the outer peripheral portion of the half-moon shaped rubber roller 2a and the rear end 2y of the outer peripheral portion between the angle α. Therefore, the sent out multiple sheets are
It is pushed up from below by the loosening pad 3, and FIG.
As shown in (a), it enters into the depression 2z.
Then, the contact pressure of the loosening pad 3 with the back surface of the plurality of sheets becomes weak, and thus the braking force becomes weak. As a result, as shown in FIG. 13B, the sheet 4b is sent to the transport roller 7 while overlapping the sheet 4a. This is the "double feed" process.

It is an object of the present invention to provide a sheet feeding roller of the sheet feeding device in which the above-mentioned double feeding does not occur.

[0016]

In order to achieve the above object, the present invention provides a paper feed roller arranged at the front end of a cassette accommodating laminated sheets and a paper feed roller arranged opposite to the paper feed roller. And a separating pad to which a pressing force is applied to the roller. The sheet feeding roller rotates while abutting on the uppermost sheet of the cassette to add a sending force by friction to the uppermost sheet. Is a sheet feeding device that feeds only one of the uppermost sheets by applying a braking force due to friction from the back surface of the sheet other than the uppermost sheet,
The half-moon shaped rubber roller fixed to the rotary shaft, and the abutment rollers arranged at both ends of the half-moon shaped rubber roller freely rotatable on the rotary shaft, the half-moon shaped rubber roller,
An outer peripheral portion that comes into contact with the uppermost sheet and a recessed portion in which a part of the outer peripheral portion is cut off are formed, and a protrusion portion having a diameter of the outermost peripheral portion smaller than the diameter of the abutting roller is provided in the recessed portion. It is a thing.

[0017]

According to the present invention, with the above-mentioned structure, the recessed portion of the half-moon shaped rubber roller is provided with the projection to prevent the fed sheet from entering the recessed portion. The force can be sufficiently exerted, and thus the probability of occurrence of double feeding can be made extremely small.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The relationship between the sheet feeding apparatus and the image forming apparatus in one embodiment of the present invention is the same as the conventional example described in FIG. Further, the configuration of the sheet feeding apparatus according to the embodiment of the present invention is configured with the same parts as those of the conventional sheet feeding apparatus described with reference to FIGS.

The present invention differs from the conventional sheet feeding apparatus in the structure of the sheet feeding roller.

Next, the paper feed roller in the first embodiment of the present invention will be described. FIG. 1 is a sectional view of a sheet feeding roller 2 according to the first embodiment of the present invention, and FIG. 2 is a perspective view of a half-moon shaped rubber roller 2a which constitutes the sheet feeding roller. As shown in FIG. 1, the sheet feeding roller portion 2 of the first embodiment of the present invention has a core portion 2c fixed to a rotating shaft 2d and a half-moon shape formed around the core portion 2c as in the conventional example. It is composed of a rubber roller 2a and abutting rollers 2b arranged on both ends of the half-moon shaped rubber roller 2a coaxially with the rotating shaft 2d. Further, as is apparent from FIG. 1, the outer periphery of the half-moon shaped rubber roller 2a is cut off by the angle α, and the outer peripheral portion 2p is left only by the angle β in FIG. This point is also shown in FIG. 1 of the conventional example.
Same as 2. However, as shown in FIG.
In the half-moon shaped rubber roller 2a of the embodiment, the depressed portion 2z
From the tip 2x of the outer peripheral portion 2p in the traveling direction of the arrow A.
The protrusion 2f is provided between the positions indicated by. Also the protrusion 2
The position of the outermost periphery of f is inside the outer periphery of the abutting roller 2b by the amount indicated by the dimension B. Since the outer circumference of the half-moon rubber roller 2a is larger than the outer circumference of the abutting roller 2b, the outer circumference of the protrusion 2f is inside the outer circumference 2p of the half-moon rubber roller 2a by the amount indicated by the dimension C. For this reason,
When the half-moon shaped rubber roller 2a rotates in the direction of arrow A along with the rotation of the rotating shaft 2d, it is the tip 2x of the outer peripheral portion 2p of FIG. 1 that first comes into contact with the uppermost sheet of the laminated sheet 4.

FIG. 3A shows a state in which the half-moon shaped rubber roller 2a has started to rotate by a paper feed command. As described above, the tip 2x of the outer peripheral portion 2p of the half-moon shaped rubber roller 2a.
First comes into contact with the uppermost sheet 4a of the laminated sheet 4 and sends out the uppermost sheet 4a by a frictional force. At this time, the above-mentioned protrusion 2f occupies a position further advanced in the traveling direction of the uppermost sheet 4a, and the uppermost sheet 4a is depressed 2
It prevents you from entering z. As a result, the braking force of the loosening pad 3 on the seat can sufficiently exert its effect. Therefore, at this time, even if not only the uppermost sheet 4a but also a plurality of sheets are sent out, the braking force of the separation pad 3 prevents the sheets from being sent out further. As a result, as shown in FIG.
Only a will be reliably sent out.

Next, the sheet feeding roller of the sheet feeding apparatus according to the second embodiment of the present invention will be described with reference to FIGS.

FIG. 4 is a sectional view of the sheet feeding roller portion 2 in the second embodiment of the present invention, and FIG. 5 is a perspective view of a half-moon shaped rubber roller 2a constituting the sheet feeding roller.

As shown in FIG. 5B, a guide member 2h having an engaging claw 2k is prepared, and the engaging claw 2k is fitted into the hole 2e of the core 2c of the half-moon shaped rubber roller 2a. As a result, as shown in the cross sectional view of FIG.
In the depressed portion 2z, there is a protrusion formed by the guide member 2h between the tip 2x of the outer peripheral portion 2p and the angle A in the traveling direction of the arrow A. Similar to the first embodiment, the outermost circumference of the guide member 2h is located inside the outer circumference of the abutting roller 2b by a dimension B and from the outer circumference of the half-moon shaped rubber roller 2a by a dimension C. For this reason, when the half-moon shaped rubber roller 2a rotates in the direction of arrow A with the rotation of the rotary shaft 2d, it is the tip 2x of the outer peripheral portion 2p that first comes into contact with the uppermost sheet of the laminated sheet 4, as in the conventional example. is there. Further, as the material of the guide member 2h, it is preferable to select a material having a friction coefficient with the sheet as small as possible.

FIG. 6 (a) shows a state in which the half-moon shaped rubber roller 2a has started to operate in response to a paper feed command. As described above, the tip 2 of the outer peripheral portion 2p of the half-moon shaped rubber roller 2a.
x first comes into contact with the uppermost sheet 4a of the laminated sheet 4, and the uppermost sheet 4a is sent out by a frictional force. At this time, the guide member 2h occupies a position advanced in the traveling direction of the uppermost sheet 4a, and prevents the uppermost sheet 4a from entering the depression 2z as in the first embodiment. As a result, the braking force of the loosening pad 3 on the seat can sufficiently exert its effect. Therefore, at this time, even if not only the uppermost sheet 4a but also a plurality of sheets are sent out, the braking force of the separation pad 3 prevents the sheets from being sent out further. As a result, FIG. 6 (b)
Only the uppermost sheet 4a is reliably delivered as shown in FIG.

In the second embodiment described above, it is desirable that the outer peripheral portion 2p of the half-moon shaped rubber roller 2a has a large friction coefficient with the sheet, but the role of the guide member 2h is that the sheet is in the recessed portion 2z of the half-moon shaped rubber roller 2a. Since it is entering, it is desirable that the friction coefficient between the guide member 2h and the sheet is small. In the second embodiment, the half-moon shaped rubber roller 2 is used.
Since the outer peripheral portion 2p of a and the guide member 2h can be made of different materials, they can be made of the most suitable material depending on the location.

Next, the sheet feeding roller of the sheet feeding apparatus according to the third embodiment of the present invention will be described with reference to FIGS.

FIG. 7 is a sectional view of a sheet feeding roller in the third embodiment of the present invention, and FIG. 8 is a perspective view of a half-moon shaped rubber roller which constitutes the sheet feeding roller.

As shown in FIG. 7, also in the half-moon shaped rubber roller 2a according to the third embodiment of the present invention, the outer peripheral portion 2 is formed in the depressed portion 2z.
A protrusion 2f is provided between the tip 2x of p and the direction indicated by the arrow A in the traveling direction of the arrow A. Further, a film (for example, a Teflon film) 2m having a small friction coefficient is attached to the outer periphery of the protrusion 2f. And the film 2
The outer periphery of the protrusion 2f to which m is attached is abutting roller 2b.
It is on the inside by the amount indicated by the dimension B from the outer circumference. Therefore, it is on the inner side from the outer peripheral portion 2p by the amount indicated by the dimension C. Therefore, the half-moon shaped rubber roller 2 is rotated along with the rotation of the rotary shaft 2d.
When a rotates in the direction of arrow A, it is the tip 2x of the outer peripheral portion 2p in FIG. 7 that first comes into contact with the uppermost sheet of the laminated sheet 4.

FIG. 9 (a) shows a state in which the half-moon shaped rubber roller 2a of the third embodiment has started to operate in response to a paper feed command. As described above, the half-moon shaped rubber roller 2 of the third embodiment.
The tip 2x of the outer peripheral portion 2p of a first contacts the uppermost sheet 4a of the laminated sheet 4, and the uppermost sheet 4a is abraded by frictional force.
Is sending out. At this time, the protrusion 2f and the film 2m occupy a position further advanced in the traveling direction of the uppermost sheet 4a, and the uppermost sheet 4a is the same as in the first embodiment.
Are prevented from entering the depressed portion 2z. As a result, the braking force of the loosening pad 3 on the seat can sufficiently exert its effect. Therefore, if not only the top sheet 4a but also a plurality of sheets are sent out at this time,
The braking force of the loosening pad 3 prevents the sheet from being further delivered. As a result, as shown in FIG. 9B, only the uppermost sheet 4a is reliably delivered.

[0031]

As is apparent from the above embodiments, according to the present invention, a protrusion is provided in the depressed portion of the half-moon shaped rubber roller,
Since the fed-out sheet is prevented from entering the recessed portion, the braking force of the separating pad for the sheets other than the uppermost sheet can be sufficiently exerted, and therefore the probability of double feeding is extremely reduced. You can

[Brief description of drawings]

FIG. 1 is a sectional view of a sheet feeding roller according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a half-moon shaped rubber roller which constitutes a paper feeding roller according to the first embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the sheet feeding apparatus using the sheet feeding roller according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a paper feed roller according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a half-moon shaped rubber roller which constitutes a paper feeding roller in a second embodiment of the present invention.

FIG. 6 is an operation explanatory diagram of a sheet feeding device using a sheet feeding roller according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a paper feed roller according to a third embodiment of the present invention.

FIG. 8 is a perspective view of a half-moon shaped rubber roller which constitutes a paper feeding roller in a third embodiment of the present invention.

FIG. 9 is an operation explanatory view of the sheet feeding device using the sheet feeding roller in the third embodiment of the invention.

FIG. 10 is a cross-sectional view of a printer equipped with the sheet feeding device of the invention and the conventional example.

FIG. 11 is a perspective view of a sheet feeding roller and a separating pad in the sheet feeding device of the present invention and the conventional example.

FIG. 12 is a sectional view of a sheet feeding roller in a conventional example.

FIG. 13 is an operation explanatory diagram of a sheet feeding device using a sheet feeding roller in a conventional example.

[Explanation of symbols]

 2 Paper feeding roller 2a Half-moon shaped rubber roller 2b Abutting roller 2c Core part 2d Rotating shaft 2e Hole 2f Projection part 2g Projection tip 2h Guide member 2k Engaging claw 2m Film 2p Outer peripheral part 2z Outer peripheral part 2x Outer peripheral part 2y Outer peripheral part Rear end of the unit 3 Separation pad 4 Laminated sheet 8 Cassette

Claims (4)

[Claims] 1. A sheet feeding roller arranged at a front end of a cassette accommodating laminated sheets, and a separating pad arranged so as to face the sheet feeding roller and a pressing force is applied to the sheet feeding roller. When the paper feed roller rotates while contacting the uppermost sheet of the cassette, frictional force is applied to the uppermost sheet, and the separating pad applies a braking force due to friction from the back surface of the sheet other than the uppermost sheet. In a sheet feeding device that feeds only one of the uppermost sheets by causing it to act, the paper feeding roller includes a half-moon shaped rubber roller fixed to a rotation shaft and a half-moon shaped rubber roller which is freely rotatable on the rotation shaft. The half-moon shaped rubber roller is composed of abutting rollers arranged at both ends, and the outer peripheral portion that abuts the uppermost sheet and a part of the outer peripheral portion are cut off. Has been the recess is further formed, the protrusions provided in the recess, the paper feed roller of the protrusion size of the outermost periphery the abutment feeding smaller sheet than the diameter of the roller apparatus. 2. The sheet feeding roller of the sheet feeding apparatus according to claim 1, further comprising a protrusion formed of a material having a small coefficient of friction with the sheet. 3. A guide member made of a material having a small coefficient of friction with a sheet is provided with engaging claws at both ends, and the engaging claws are engaged with holes provided in a core portion for fixing a half-moon shaped rubber roller to a rotary shaft. The sheet feeding roller of the sheet feeding device according to claim 1, wherein the sheet feeding roller according to claim 1 is formed as a protrusion in a depressed portion of the half-moon shaped rubber roller by combining them. 4. The sheet feeding roller of the sheet feeding apparatus according to claim 1, wherein a film made of a material having a small coefficient of friction with the sheet is attached to the outer periphery of the protrusion provided in the depressed portion.