JP2002154694A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate an abnormal sound at operation time by preventing a stick slip between a pickup roller and a pressurizing plate when feeding the final paper. SOLUTION: Even if paper P runs out after the rear end in the feeding final paper passes through the pickup roller 5, an end part of a sheet member 22 exists in a nip N1 of the pickup roller 5 and the pressurizing plate 6 to solve a conventional problem of generating the abnormal sound by microvibration at slip time when the pressurizing plate 6 causes the stick slip in a direct abutting surface with the pickup roller 5. An intermediate sheet member 20 is interposed between the pressurizing plate 6 and the sheet member 22, and prevents the pressurizing plate 6 and the sheet member 22 from being brought into close contact with each other to maintain the effect of the sheet member 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a paper feeding section of a facsimile machine, a copying machine, a printer, or the like, and presses a sheet against a pickup roller by a swingable pressing plate.
The present invention relates to a sheet feeding device configured to feed a sheet by rotation of a pickup roller.

[0002]

2. Description of the Related Art FIG. 7 is a schematic structural view of an image reading apparatus for explaining the structure of a conventional paper feeding apparatus. Reference numeral 1 denotes an apparatus main body, on which a bundle of sheets P such as originals is set. A set table 2 is provided, and a cover body 4 serving also as an upper guide plate for sheet conveyance is provided so that the sheet conveyance path 3 can be opened and closed. A pickup roller 5 rotatably supported on the apparatus body 1 side and in contact with the lowermost sheet of the bundle of sheets P is provided on the side of the apparatus main body 1 in the set table 2 portion. A pressure plate 6 is provided, which is in contact with the portion 6a and whose other end 6b is pivotally supported by the cover body 6c. An urging spring 7 is provided at one end 6a of the pressure plate 6, and presses the one end 6a toward the pickup roller 5.

On the downstream side of the pickup roller 5 in the sheet feeding direction, there is provided a separation roller unit 9 provided with a separation roller 8 and a separation sheet feeding section 11 comprising a feed roller 10 and the like. Paper section 11
Downstream of the paper feeding direction, two pairs of transport rollers 12, 1
3 is provided, and an image reading sensor 14 is provided between the transport roller pairs 12 and 13.

The operation of the image reading apparatus will be described. The leading end of a bundle of sheets P set on a set table 2 is inserted into a nip N ₁ between a pickup roller 5 and a pressure plate 6.
In this state, since the sheet P bundle is pressed by the one end 6 a of the pressing plate 6 which receives the urging force of the urging spring 7, the lowermost sheet elastically contacts the upper side of the pickup roller 5.

[0005] When the driving is started, the pickup roller 5 rotates, and the bundle of sheets P is pressed by the pressing plate 6.
In the state where the sheet is pressed by the
Is fed to In the nip N ₂ between the separation roller 8 and the feed roller 10 in the separation sheet feeding section 11, the separation roller 8
The coefficient of friction between the sheet P and the sheet P, the coefficient of friction between the sheets P, and the coefficient of friction between the sheet P and the feed roller 10 are set so that only the bottom sheet of the sheet P bundle is separated and fed. The bundle of sheets P fed from the pickup roller 5 is
Are rotated, one by one becomes a pair of transport rollers 12,1.
It will be sent in three directions. The transport rollers 12 and 13 transport the paper (document) P at a predetermined speed, and the image information is read by the image reading sensor 14. After the reading is completed, the paper P is discharged to the outside by the transport roller 13.

[0006] Thus, the conventional paper feeder includes:
Since the configuration is such that a plurality of sheets P bundles are separated and fed one by one in a predetermined direction from the set state, this is effective when employed in an image reading apparatus or the like that needs to read document information one by one.

[0007]

In the conventional paper feeder, even if the paper feed advances and the trailing end of the last paper passes over the pickup roller 5, the image reading sensor 14 for the last paper is required. The drive is transmitted to the pick-up roller 5 until the reading is completed and the paper discharge is completed.

For this reason, the pickup roller 5 is rotated until the driving is stopped after the ejection of the last sheet is completed, and as shown in FIG. 8, the pressure of the pressing plate 6 receiving the urging force of the urging spring 7 is reached. The one end 6 a comes into direct contact with the rotating pickup roller 5.

Therefore, during this time, the pickup roller 5 is continuously rubbed by the pressure plate 6, and the pressure plate 6 swings around the pivot 6c. There is a problem that stick-slip occurs on the contact surface with No. 5, and abnormal noise (chattering noise) is generated due to slight vibration at the time of the slip.

Therefore, the present applicant has filed Japanese Patent Application No.
No. 9885 (JP-A-2000-95355), a sheet member is interposed in the nip portion when there is no paper in the nip between the pickup roller and the pressure plate,
A structure has been proposed in which the occurrence of the abnormal noise during operation is prevented by preventing the pickup roller and the pressure plate from directly contacting each other.

However, even when the above-mentioned structure is employed, abnormal noise may be generated. The cause is that the pressure plate and the sheet member adhere to each other. At this time, if stick slip occurs between the sheet member and the pickup roller,
The minute vibration of the sheet member is transmitted to the pressure plate having the swing structure, and as a result, an abnormal noise is generated as in the related art.

The present invention solves the above-mentioned conventional problems, and prevents stick-slip between the pickup roller and the pressure plate at the time of feeding the final sheet, thereby eliminating the generation of abnormal noise during operation. It is an object of the present invention to provide a paper feeding device which has been described.

[0013]

In order to achieve the above object, according to the present invention, a pickup roller contacting a lower side of a sheet to be stacked and a pickup roller contacting an upper side of the sheet via a sheet member. A sheet feeder that includes a swingable pressure plate that presses a sheet against the pickup roller, and feeds the sheet in a predetermined direction such that the sheet is sandwiched by a nip portion between the pickup roller and the pressure plate via the sheet member; Wherein an intermediate sheet member is interposed between the pressing plate and the sheet member. With this configuration, slippage is likely to occur between the pressing plate and the sheet member due to the presence of the intermediate sheet member. It is possible to prevent close contact between the pressure plate and the sheet member, prevent stick-slip at the nip portion, and eliminate occurrence of abnormal noise.

According to a second aspect of the present invention, in the paper feeder according to the first aspect, the intermediate sheet member has a length substantially the same as the length of the sheet member in the sheet conveying direction and is perpendicular to the sheet conveying direction. The length of the sheet is shorter than that of the sheet member. With this configuration, a space is created due to the presence of the intermediate sheet member between the pressure plate and the sheet member. Can be prevented.

The third aspect of the present invention provides the first or second aspect.
The sheet feeding device according to the above, wherein the sheet member and the intermediate sheet member are thin films having a thickness of about 0.2 mm or less. , Which does not affect the pressing force of the pressure plate that affects the pressure.

According to a fourth aspect of the present invention, in the paper feeder of the first, second or third aspect, the sheet member and the intermediate sheet member are formed of an elastic material. The sticking vibration generated between the pickup rollers can be absorbed and attenuated by the sheet member and the intermediate sheet member.

According to a fifth aspect of the present invention, there is provided a pickup roller which comes into contact with a lower side of a sheet to be stacked, and a swingable pressing member which comes into contact with an upper side of the sheet via a sheet member and presses the sheet against the pickup roller. A sheet feeding device that includes a pressure plate and feeds a sheet in a predetermined direction so as to sandwich a sheet by a nip portion between the pickup roller and the pressure plate via the sheet member; In this configuration, a protrusion is provided between the pressure plate and the sheet member, so that a space is generated due to the presence of the protrusion between the pressure plate and the sheet member.
By preventing stick-slip in the nip portion, it is possible to eliminate occurrence of abnormal noise.

According to a sixth aspect of the present invention, in the paper feeder according to the fifth aspect, a length of the projection member in a direction perpendicular to the sheet conveying direction is substantially 1/6 of a pickup roller width.
In addition, a small piece having a thickness of about 0.2 mm or less is characterized in that the small piece interposed between the pressure plate and the pickup roller has a size that does not affect the transport performance.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image reading apparatus for explaining a first embodiment of the present invention. The basic configuration is the same as that of the apparatus described with reference to FIG. Are described with the same reference numerals.

In FIG. 1, reference numeral 1 denotes an apparatus main body, on which a set table 2 on which a bundle of sheets of paper P such as originals is set is installed, and the sheet is conveyed so that a sheet conveying path 3 can be opened and closed. A cover body 4 also serving as an upper guide plate is provided. A pickup roller 5 rotatably supported on the apparatus main body 1 side and in contact with the lowermost sheet of the bundle of sheets P is provided on the side of the apparatus main body 1 in the set table 2 portion. A pressure plate 6 is provided, which is in contact with the portion 6a and whose other end 6b is pivotally supported by the cover body 6c. An urging spring 7 is provided at one end 6a of the pressure plate 6.
Is provided to press the one end 6a toward the pickup roller 5.

On the downstream side of the pickup roller 5 in the paper feeding direction, there is provided a separation paper feeding unit 11 composed of a separation roller unit 9 provided with a separation roller 8 and a feed roller 10. Paper section 11
Downstream of the paper feeding direction, two pairs of transport rollers 12, 1
3 is provided, and an image reading sensor 14 is provided between the transport roller pairs 12 and 13.

Further, in the first embodiment, as shown in an exploded perspective view of the pressing plate portion shown in FIG. 2, in the set base 2 portion, one end portion 20a is provided with an adhesive 21 or the like on the projecting inclined portion 4a of the cover body 4. And the other end 20b is fixed to the pressing plate 6
An intermediate sheet member 20 is provided so as to be in contact with one end 6a of the intermediate sheet member 20, and further extends below the intermediate sheet member 20, and one end 22a is fixed to the intermediate sheet member 20 using an adhesive 21 or the like. The end 22b is the pickup roller 5
The sheet member 22 is provided so as to be in contact with.

The operation of the image reading apparatus having the above configuration will be described. The leading end of the bundle of sheets P set on the set table 2 is inserted into the nip N ₁ between the pickup roller 5 and the pressure plate 6. In this state, since the sheet P bundle is pressed by the one end 6 a of the pressing plate 6 which receives the urging force of the urging spring 7, the lowermost sheet elastically contacts the upper side of the pickup roller 5.

When the driving starts, the pickup roller 5 rotates, and the bundle of sheets P is pressed by the pressing plate 6.
In the state where the sheet is pressed by the
Is fed to In the nip N ₂ between the separation roller 8 and the feed roller 10 in the separation sheet feeding section 11, the separation roller 8
The coefficient of friction between the sheet P and the sheet P, the coefficient of friction between the sheets P, and the coefficient of friction between the sheet P and the feed roller 10 are set so that only the bottom sheet of the sheet P bundle is separated and fed. The bundle of sheets P fed from the pickup roller 5 is
Are rotated, one by one becomes a pair of transport rollers 12,1.
It will be sent in three directions. The transport rollers 12 and 13 transport the paper (document) P at a predetermined speed, and image information is read by the image reading sensor 14. After the reading is completed, the paper P is discharged to the outside by the transport roller 13.

In the present embodiment, when the paper feed advances and the trailing end of the last paper passes over the pickup roller 5 and the paper P runs out, the nip N ₁ between the pickup roller 5 and the pressure plate 6 is reached. The other end 22 of the sheet member 22
Since b exists, the problem that the pressure plate 6 causes stick-slip on the direct contact surface with the pickup roller 5 and generates abnormal noise (chattering noise) due to slight vibration at the time of the slip is solved. be able to.

By the way, even if the sheet member 22 is provided, if the sheet member 22 comes into close contact with the pressure plate 6 and is integrated, it is substantially the same as the occurrence of stick slip with respect to the pressure plate 6. , Micro vibrations are transmitted.
For this reason, in the present embodiment, the intermediate sheet member 20 is interposed between the pressing plate 6 and the sheet member 22 so that the sliding occurs between the pressing plate 6 and the sheet member 22 so that the pressing plate 6 and the sheet member 22 Are prevented from sticking together.

In the present embodiment, the sheet member 22 and the intermediate sheet member 20 are attached to the cover body 4, and a direct attachment structure is employed in which the sheet member 22 and the intermediate sheet member 20 are attached to the pressing plate 6 with an adhesive. I try not to.

The reason for this is that sticking vibration cannot be absorbed and attenuated by the pressure plate 6 having a swinging structure, and the generated vibration is not transmitted to the pressure plate 6. This is because this is the best method for eliminating occurrence of abnormal noise during operation. When the sheet member 22 and the intermediate sheet member 20 are directly attached to the pressure plate 6, stick-slip also occurs on the contact surface between the sheet member 22 and the pickup roller 5, so that minute vibrations in the sheet member 22 and the intermediate sheet member 20 fluctuate. This is transmitted to the pressure plate 6 having a dynamic structure, and as a result, generation of abnormal noise cannot be prevented.

The sheet member 22, the intermediate sheet member 2
0 intervenes in the nip N ₁ between the pickup roller 5 and the pressure plate 6, and therefore, depending on the thickness of the sheet member 22 and the intermediate sheet member 20, the pressing force (the pressure plate) on the pressure plate 6 that changes depending on the swing stroke. 6 to the pickup roller 5), the sheet thickness should be as thin as possible.
About 0.2 mm is desirable.

The sheet member 22, the intermediate sheet member 2
As the material of the material No. 0, it is desirable to use an elastic member made of a thermoplastic resin such as PET (polyethylene terephthalate) resin.
2, by interposing the intermediate sheet member 20 to the nip N ₁ between the pickup roller 5 and the pressure plate 6, the sheet member 22 sticking vibration generated in between the sheet member 22 and the pickup roller 5, the intermediate sheet member 2
At 0, the absorption can be attenuated.

FIG. 3 is a plan view for explaining an arrangement relationship between the pressing plate, the sheet member, and the intermediate sheet member in the first embodiment. The intermediate sheet member 20 has a length in the sheet conveying direction (arrow X direction). Is substantially the same as the sheet member 22, and has a sheet shape having a length in a direction (arrow Y direction) orthogonal to the sheet conveying direction is shorter than the sheet member 22. As a result, a space 23 is created between the pressing plate 6 and the sheet member 22 due to the presence of the intermediate sheet member 20 having a small width, as shown in FIG. It is possible to more reliably prevent the member 22 from being in close contact.

FIG. 5 is a front view showing an arrangement relationship between a pressing plate and a sheet member for explaining a second embodiment of the present invention.
FIG. 6 is a bottom view showing an arrangement relationship between the pressure plate and the sheet member in FIG. 5. The second embodiment is different from the first embodiment in that a projection member 25 is provided at a nip portion N ₁ between the pressure plate 6 and the pickup roller 5. It is the point that was installed.

For this reason, the intermediate sheet member 20 shown in FIG.
Similarly, since the space 26 is created between the pressure plate 6 and the sheet member 22 due to the presence of the projection member 25, it is possible to prevent the pressure plate 6 and the sheet member 22 from being in close contact with each other,
Like the first embodiment, to prevent the stick-slip in the nip N ₁ part, it can be eliminated occurrence of noise.

The length of the projecting member 25 in the direction Y perpendicular to the sheet conveying direction X is approximately 1/6 of the width of the pickup roller 5 and the thickness (projection height) is approximately 0.2 mm.
By using the following small pieces, it is possible to prevent the transfer performance from being affected even when the projecting member 25 is provided.

[0036]

As described above, according to the paper feeder of the present invention, the sheet member is interposed in the nip between the pickup roller and the pressure plate, so that the pickup roller and the pressure plate come into direct contact with each other. Can be eliminated,
Since it is possible to prevent the occurrence of stick-slip and micro-vibration between the two devices during the conventional operation, troubles such as generation of abnormal noise during the operation can be eliminated.
Furthermore, since the intermediate sheet member or the protruding member is interposed between the pressing plate and the sheet member, it is possible to prevent the pressing plate and the sheet member from being in close contact with each other. The effect can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus for explaining a first embodiment of the present invention;

FIG. 2 is an explanatory diagram of attachment of a sheet member and an intermediate sheet member according to the embodiment of the present invention.

FIG. 3 is a plan view for explaining an arrangement relationship between a pressing plate, a sheet member, and an intermediate sheet member in the first embodiment.

FIG. 4 is a view taken in the direction of arrow A in FIG. 3 for explaining an arrangement relationship between a pressing plate, a sheet member and an intermediate sheet member.

FIG. 5 is a front view showing an arrangement relationship between a pressing plate and a sheet member for describing a second embodiment of the present invention.

FIG. 6 is a bottom view illustrating an arrangement relationship between a pressing plate and a sheet member according to a second embodiment.

FIG. 7 is a schematic configuration diagram of an image reading device for explaining a configuration of a conventional paper feeding device.

FIG. 8 is an explanatory diagram for explaining a problem of a conventional sheet feeding device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Apparatus main body 4 Cover body 5 Pickup roller 6 Pressure plate 7 Urging spring 8 Separation roller 10 Feed roller 20 Intermediate sheet member 22 Sheet member 25 Projection member N ₁ Nip between pickup roller and pressure plate N ₂ Separation roller and feed roller Nip

Claims (6)

[Claims] A pickup roller that contacts a lower side of a sheet to be stacked, and a swingable pressure plate that contacts an upper side of the sheet via a sheet member and presses the sheet against the pickup roller; In a sheet feeding device for feeding a sheet in a predetermined direction by sandwiching a sheet by a nip portion between a roller and the pressing plate via the sheet member, an intermediate sheet member is interposed between the pressing plate and the sheet member. A sheet feeding device. 2. The intermediate sheet member, wherein a length of the intermediate sheet member in a sheet conveying direction is substantially the same as that of the sheet member, and a length of the intermediate sheet member in a direction orthogonal to the sheet conveying direction is shorter than the sheet member. The sheet feeding device according to claim 1, wherein 3. The sheet feeding device according to claim 1, wherein the sheet member and the intermediate sheet member are thin films having a thickness of about 0.2 mm or less. 4. The apparatus according to claim 1, wherein said sheet member and said intermediate sheet member are formed of an elastic material.
4. The paper feeder according to 2 or 3. 5. A pickup, comprising: a pickup roller that contacts a lower side of a sheet to be stacked; and a swingable pressure plate that contacts an upper side of the sheet via a sheet member and presses the sheet against the pickup roller. In a paper feeding device for feeding a sheet in a predetermined direction so as to sandwich a sheet by a nip portion between a roller and the pressing plate via the sheet member, a protrusion member in contact with the sheet member is interposed at the nip portion of the pressing plate. A paper feeder characterized by having been made to. 6. The projection member is a small piece having a length in a direction perpendicular to the sheet conveying direction that is substantially 1/6 of the width of the pickup roller and a thickness of about 0.2 mm or less. The sheet feeding device according to claim 5, wherein