JPH10120226A - Automatic paper conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separatively feed paper, placed on a paper placing part, positively sheet by sheet without being influenced by the reidual number of sheets and thickness of paper in an automatic paper conveying device using a reverse roller and a feed roller. SOLUTION: A pressure contact sheet 12 comes in pressure contact with paper D on the conveying direction lower reaches of a pressure holding lever 3 and in an area on the upper reaches of a reverse roller 5. Plural sheets of paper D are pushed out by a pickup roller 4 and inserted in a nip part between the reverse roller 5 and a feed roller 6. Frictional resistance to the pressure contact sheet 12 corresponding to pressure from the pressure contact sheet 12, frictional resistance to a document placing face 1a and frictional resistance to the paper D therefore act upon the paper D pushed out by the pickup roller 4, and these forces suppress the inertial movement of the paper D pushed back by the reverse roller 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sheet conveying apparatus for separating and conveying sheets one by one from a bundle of sheets such as originals in a copying machine, a facsimile machine, a scanner, or the like.

[0002]

2. Description of the Related Art FIG. 2 is a view showing the construction of a main part of an example of a conventional scanner device provided with an automatic document feeder, wherein reference numeral 1 denotes a document placing plate on which a document D for reading an image is placed; Is a guide plate formed with a guide surface 2a continuous with the original placing surface 1a of the original placing plate 1, and 3 is a direction of the original placing plate 1 by an elastic member (not shown) such as a coil spring arranged on the support shaft side. Is a pickup roller disposed below the pressure holding lever 3, and the pickup roller 4 has a substantially oval cross-sectional shape in the axial direction. It is supported by the drive shaft 4a at an eccentric position deviated to one end of the cross section. 5 is a pickup roller 4
The reverse roller 5 is disposed at a separation sheet feeding position on the downstream side of the reverse direction. The reverse roller 5 is provided with a reverse torque in the reverse rotation direction to the conveyance direction via a torque limiter (not shown) which is a torque transmission control member. Is transmitted. The torque limiter is configured such that when a rotation resistance greater than a preset value acts on the reverse roller 5, the torque transmission to the reverse roller 5 is interrupted and idle. 6
Reference numeral denotes a feed roller which is arranged at the separation sheet feeding position and forms a roller pair together with the reverse roller 4. A feed torque in the transport rotation direction is transmitted to the feed roller 6.

[0003] Reference numeral 7 denotes a white reference plate which is buried in the guide plate 2 at a reading position on the downstream side of the separation sheet feeding position.
Has a predetermined reflectance. Reference numeral 8 denotes a reading unit disposed on the upper surface of the white reference plate 7,
It has a built-in line sensor such as a CCD (Charge Coupled Device). Reference numerals 9 and 10 denote transport roller pairs disposed on the upstream and downstream sides of the reading position, respectively.

FIGS. 3 and 4 are explanatory views of the transport operation in the scanner device shown in FIG. 2, respectively. The document transport and reading operations in the scanner device shown in FIG. 2 will be described with reference to FIGS. The bundle of originals D placed on the original placing plate 1 is inserted between the pressure holding lever 3 and the original placing plate 1 along the original placing surface 1a. This manuscript D
Is positioned at the loading position by abutting against a reverse roller 5 having a function as a stopper. In this state, the bundle is placed on the original placing plate 1 as shown in FIG. When the loading is completed, the document D can be separated and fed one by one. Pressure holding lever 3
Is pressed against the original D placed on the original placing plate 1 from above and presses the original D against the original placing surface 1a, so that the original D has a certain moving resistance with respect to the original D on the original placing plate 1. Is given.

When the separation feeding of the original D is started, the torque from the conveyance motor is transmitted via a clutch mechanism (not shown) so that the pickup roller 4 rotates exactly once in one separation feeding operation. Is transmitted. Pickup roller 4 formed in a non-circular shape and supported at an eccentric position
3, the roller surface 4a does not protrude from the original placing surface 1a in the initial phase as shown in FIG. 3, and the roller surface 4a is placed only in a partial phase section after the start of rotation as shown in FIG. The roller surface 4a is pressed against the lowermost document D in this phase section. As a result, a force in the transport direction is directly applied to the lowermost original D by the pickup roller 4 and the lowermost original D
The force in the transport direction is also transmitted to the documents D stacked on the document D by the frictional force generated between the documents D. One or more originals D, including the lowermost one, are pushed out of the bundle of originals D placed on the original placing plate 1 in the transporting direction by the force in the transporting direction transmitted from the pickup roller 4, and are fed to the feed roller 6. Is inserted into a nip portion which is a pressure contact portion between the roller and the reverse roller 5.

On the other hand, at the time of separation and feeding, the transmission of the reverse torque to the reverse roller 5 via the torque limiter is continued, and the feed torque is transmitted to the feed roller 6.
When the original is completely in contact with the feed roller 6 and when only one document D is held between the feed roller 6 and the feed roller 6, a relatively large frictional force is applied. The roller 6 is driven to rotate. Further, the reverse roller 5 is not completely in contact with the feed roller 6, and when a plurality of (two or more) originals D are sandwiched between the feed roller 6 and the Since the frictional force is relatively smaller than the frictional force between the reverse roller 5 and the document D, the reverse rotation is performed by the reverse torque transmitted through the torque limiter,
The original D excluding the lowermost portion is pushed back from the nip toward the loading position.

Accordingly, the rollers 4 to 6 operate as described above, so that while the pickup roller 4 makes one rotation, the bundle of the originals D placed on the loading position of the original placing plate 1 is removed from the bundle. Only the lower one document D is transported downstream from the separation sheet feeding position, and this one document D is transported by the transport roller pair 9.
To the reading position. Here, the presence or absence of the original D on the original placing plate 1 is detected by a sensor (not shown), and the separation and feeding operation is repeated until the sensor detects the absence of the original D. When only one original D is placed on the original placing plate 1, the one original D
Is pushed out to the separation sheet feeding position by the pickup roller 4, and is immediately conveyed to the downstream side by the feed roller 6 and the reverse roller 5, and the separation sheet feeding operation is completed in one time.

A pair of conveying rollers 9 and a pair of conveying rollers 10 arranged downstream thereof convey the document D such that the document D moves at a constant reading speed at the reading position. At the reading position, the reading unit 8 scans the document D with a line sensor at a period corresponding to the reading pitch in the main scanning direction and outputs a line signal corresponding to an image on a scanning line.
The document D that has passed the reading position is discharged to a predetermined document discharge unit such as a discharge tray by a pair of conveying rollers 10 and a pair of conveying rollers further downstream (not shown).

[0009]

However, when the number of originals D placed on the original placing plate 1 is small as shown in FIG. 5, especially when this original D is thin, When the pickup roller 4 is in the initial phase, a gap is formed between the pressure holding lever 3 and the document D, and the pressure holding lever 3 can exert a sufficient pressing force on the document D. The phenomenon that disappears easily occurs. In such a state, the movement resistance to the document D and the frictional force between the documents D, which are provided by the pressing force from the pressure holding lever 3, become smaller than appropriate values.

When a plurality of originals D are pushed out to the separated sheet feeding position by one rotation of the pickup roller 4, the movement resistance of the originals D on the original placing plate 1 by the pressure holding lever 3 and the If the frictional resistance between the originals D is smaller than an appropriate value, the amount of movement of the originals D except for the lowermost portion pushed back by the force from the reverse roller 5 increases due to inertia. At this time, if the original D moves outside the pressure holding lever 3, the original D is moved by the pickup roller 4.
Cannot be pushed out in the conveyance direction, and the document D cannot be separated and fed even though the document D remains on the document placing plate 1, and even if the document D is below the pressure holding lever 3, the document D Since the distance between the leading end of the document D and the separation sheet feeding position increases, even if the document D is pushed out by the pickup roller 4, the occurrence of separation sheet mistakes due to the document D not reaching the separation sheet feeding position increases.

[0011] It is an object of the present invention to provide an automatic sheet feeding apparatus using a reverse roller and a feed roller, wherein the sheet placed on the sheet placing portion is not affected by the number of remaining sheets and the thickness of the sheet. An object of the present invention is to provide an automatic sheet transporting apparatus that can reliably feed and separate sheets one by one.

[0012]

In order to achieve the above object, an automatic paper transport apparatus according to claim 1 of the present invention is arranged such that, at a downstream side in a transport direction from a pressing position by a pressure holding member, And a sheet-shaped press-contact member that presses the sheet onto the sheet mounting portion and applies a frictional force to the sheet while pressing the sheet against the sheet in an area upstream of the separation sheet feeding position in the transport direction. is there. According to this automatic paper transport device, when a plurality of papers are extruded by the pickup roller, these papers are applied to the nip portion of the reverse roller and the feed roller in a state where a pressing force and a frictional force are applied by the pressing member. By being inserted, the frictional resistance between the paper pressed by the pickup roller, the frictional resistance against the pressing member corresponding to the pressing force from the pressing member, the frictional resistance against the document placing portion, and the frictional force between the papers are applied. However, these forces suppress the movement of the paper pushed back by the reverse rotating reverse roller.

According to a second aspect of the present invention, in the paper transport mechanism, the pressure contact member is formed of an elastic material, and the pressure contact member presses the sheet against the sheet placement portion by an elastic force and applies a frictional force to the sheet. It works. According to this automatic sheet transport device, the pressure contact member applies a pressure contact force that is distributed substantially uniformly to the sheet without being affected by the remaining number or thickness of the sheet on the sheet placement unit. In addition, it is possible to prevent the paper pushed out from the pickup roller from being skewed (skewed) due to uneven pressure of the pressing member in the paper width direction.

According to a third aspect of the present invention, in the paper transport mechanism, the pressing member is formed of a flexible material, and the pressing member presses the paper against the paper mounting portion by its own weight and applies a frictional force to the paper. It works. According to this automatic paper feeder, the pressure of the pressing member against the paper can be prevented from fluctuating due to the remaining number of papers placed on the paper mounting portion and the thickness of the paper. Separated sheet feeding for sheets on a set can be performed more reliably.

According to a fourth aspect of the present invention, in the paper transport mechanism, the pressing member is formed by a brush made of a bundle of a plurality of fibrous materials. A force is applied.
According to this automatic paper feeder, the change in the repulsive force with respect to the deformation amount of the fibrous material is smaller than that of the press-contact member made of a single elastic body. Can be suppressed due to the remaining number of sheets placed on the sheet tray and the thickness of the sheets, and the separation and feeding of the sheets on the sheet placement unit can be performed more reliably.

According to a fifth aspect of the present invention, in the paper transport mechanism, a conductive portion formed of a conductive material is provided on the pressing member, and the conductive portion is brought into contact with a sheet on a sheet placing portion. It is grounded to the frame portion of the device, a ground circuit, and the like. According to this automatic paper transport apparatus, it is possible to prevent the paper from being triboelectrically charged and to generate an attraction force between the papers due to static electricity. It can be prevented from being sure.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main part configuration diagram of an automatic document feeder according to an embodiment of the present invention.
The members corresponding to the members described with reference to FIG. 5 are denoted by the same reference numerals, and the description thereof will be omitted. 11 is a holder having an upper end fixed to a frame portion of the apparatus, and 12 is a holder 11
The press-contact sheet 12 is fixed to the lower end portion of the document D. The press-contact sheet 12 is separated from a position where the document D is pressed by the pressure holding lever 3 in the conveying direction of the document D, that is, the reverse roller 5 and the feed roller 5. 6, the document D is pressed against the document D in a region upstream of the nip portion to press the document D against the document placing plate 1 and apply a frictional force to the document D.

The pressure contact sheet 12 is made of, for example, PET (polyethylene terephthalate), PC (polycarbonate),
An elastic material such as vinyl chloride is formed in a thin plate shape. The elastic material is pressed against the document placing surface 1a and is bent to the downstream side in the transport direction, so that an elastic restoring force is always exerted on the document placing surface 1a. Acting in the direction. Further, in order to prevent the lower end portion of the pressure contact sheet 12 from being caught in the nip portion between the reverse roller 5 and the feed roller 6 in the transport direction, and to secure a sufficient contact area with the document D, It is assumed that a portion overlapping the nip portion is cut out in a concave shape. Accordingly, the pressure contact sheet 12 is pressed against the document D in a region downstream of the pressing position of the document D by the pressure holding lever 3 in the transport direction and upstream of the separation sheet feeding position in the transport direction. And the original D on the original placing surface 1
a and press the original D
The frictional force corresponding to the pressing force is applied to the pressure.

When the separation and feeding operation for the original D placed on the original placing plate 1 is started, the pickup roller 4 is rotated once so that the original is transferred by the force in the transport direction transmitted from the pickup roller 4. One or more originals D, including the lowermost one, are pushed out of the bundle of originals D placed on the mounting plate 1 in the transport direction and inserted into the nip between the feed roller 6 and the reverse roller 5. At this time, when only one sheet of the document D is inserted into the nip portion by the pickup roller 4, the document D is conveyed to the downstream side by the feed roller 6 and the reverse roller 5 driven and rotated by the feed roller 6. . Here, the press-contact sheet 12 applies a pressing force and a frictional force to the document D until the document D comes out of the nip portion between the reverse roller 5 and the feed roller 6. Is set to be sufficiently small with respect to the document D, so that the conveyance of the document D is not affected.

On the other hand, when a plurality of originals D are pushed out by the pickup roller 4, these originals D
The sheet is inserted into the nip portion of the reverse roller 5 and the feed roller 6 in a state where a pressing force and a frictional force are applied by the pressing sheet 12. As a result, the document D extruded by the pickup roller 4 has a frictional resistance between the original D and the original D, which corresponds to the pressing force from the press-contact sheet 12, and a frictional resistance with the original placing surface 1a. Friction forces act, and these forces suppress the movement of the document D pushed back by the reverse roller 5 rotating in the reverse direction due to the inertial force.

In the automatic document feeder of the present embodiment described above, the remaining number of the originals D placed on the original placing plate 1 is small, and the originals D are thin. The pressure holding lever 3 cannot apply a sufficient pressing force to the document D, and the pressure holding lever 3
Even if the movement resistance to the document D given by the pressing force from the roller becomes smaller than an appropriate value, the reverse roller 5
The movement of the document D pushed back due to the pressure can be suppressed by the pressing force from the pressure contact sheet 12, so that the document D may move outside the pressure holding lever 3,
It is possible to prevent the distance between the leading edge of the document D and the separation sheet feeding position from increasing. As a result, even if the document D remains on the document placing plate 1, separation feeding becomes impossible, and the distance between the leading edge of the document D and the separation feeding position increases, thereby causing a separation feeding error. Is increased, and reliable separation paper feeding is always possible.

In the automatic document feeder of this embodiment described above, the press-contact sheet 12 is formed of an elastic material, and the press-contact sheet 12 is elastically deformed to generate a press-contact force against the document D. If you use
Plastic deformation (shattering) occurs due to repeated stress acting on the press-contact sheet 12, and the press-contact force against the document D decreases over time, or the height of the bundle of the document D on the document placing plate 1 increases. Accordingly, there arises a problem that the pressing force of the pressing sheet 12 against the document D changes, and there is a possibility that the separation and feeding of the document D becomes unstable.

Therefore, instead of the pressure contact sheet 12 made of an elastic material, a pressure contact sheet 21 made of a flexible material such as a cloth or a sheet of paper fiber is used, and the pressure contact sheet 21 is moved by its own weight to the original. The document D is pressed against the document placing surface 1a and a frictional force acts on the document D. As a result, the influence of the remaining number of the originals D placed on the original placing plate 1 and the thickness of the originals D to prevent the pressing force against the original D from fluctuating can be prevented. Separation and feeding of the document D can be performed more reliably.

Also, instead of pressing the sheet 12 made of an elastic material, the original D is pressed against the original placing surface 1a by a pressing brush (not shown) made of a bundle of fibrous materials, and a frictional force is applied to the original D. Even when it is made to act, the change in the repulsive force with respect to the amount of deformation of the fibrous material is smaller than that of the pressing sheet 12 made of a single elastic body.
Can be suppressed from being affected by the remaining number of the originals D placed on the original placing plate 1 and the thickness of the originals D, which is similar to the case where the pressure contact sheet 21 is used. An effect can be obtained.

By using the press-contact sheets 12 and 21 or the press-contact brushes described above, the reduction of the pressing force on the document D by the pressure holding lever 3 is compensated, and the document D on the document placing plate 1 is As a result, it is possible to reliably perform the separation paper feeding. However, when the separation and feeding operation for the original D is repeated on the original mounting plate 1, the original D is frictionally charged, and an electrostatic attraction is generated between the originals D by the static electricity. It may be difficult to separate one original D from another original D.

In the automatic document feeder of the present embodiment, in order to prevent the reliability of the separation and feeding of the document D from being reduced due to the frictional charging of the document D as described above,
At least a part of the contact portions between the pressing sheets 12, 21 and the pressing brush with the document D is formed of a conductive material, and the conductive portion formed of the conductive material is grounded to a frame portion or a ground circuit of the apparatus. . Specifically, the pressure contact sheet
12, 21 or the pressure contact brush itself is made of conductive metal,
A conductive portion is formed on the press-contact sheets 12, 21 or the press-contact brush by dispersing a conductive material such as carbon or depositing or plating a metal thin film on a part of the surface.

A conductive portion is provided on the pressing sheets 12, 21 or the pressing brush, and the conductive portion is grounded to a frame portion of the apparatus, a ground circuit, or the like. Since the generation of force can be prevented, it is possible to prevent the separation of the document D at the separation feeding position from being uncertain due to such electrostatic force.

[0028]

As described above, according to the first aspect of the present invention,
According to the automatic paper transport device described in the above, the paper is pressed against the paper in a region downstream in the transport direction from the pressing position by the pressure holding member and in an area upstream in the transport direction from the separation paper feed position. By providing a sheet-like pressing member that presses the paper onto the paper mounting portion and exerts a frictional force on the paper, when a plurality of papers are extruded by the pickup roller, these papers are pressed against each other. Since the sheet is inserted into the nip portion of the reverse roller and the feed roller while the pressing force and the frictional force are applied by the member, the paper extruded by the pickup roller is provided between the pressing member corresponding to the pressing force from the pressing member. The frictional resistance, the frictional resistance with the document placing portion, and the frictional force between the papers are applied, and these forces are caused by the inertial force of the paper pushed back by the reverse rotating reverse roller. To suppress the movement. As a result, the remaining number of sheets placed on the sheet placing portion is small or the sheet is thin, so that the movement resistance applied to the sheet by the pressure holding member becomes smaller than an appropriate value. In this case, the movement of the paper pushed back by the reverse roller at the time of separation and feeding can be suppressed by the pressing force from the pressing member, so that the paper moves outside the pressure holding member, Because the distance between the leading edge and the separation paper feeding position can be prevented from increasing, separation paper feeding cannot be performed despite paper remaining in the paper tray, or the distance between the leading edge of the paper and the separation paper feeding position can be reduced. Prevents the occurrence of separation paper feeding errors from becoming excessively large, thereby ensuring reliable separation paper feeding at all times.

According to the second aspect of the present invention, the pressing member is formed of an elastic material, and the pressing member presses the sheet against the sheet placing portion by the elastic force, and at the same time, frictional force is applied to the sheet. Is applied, the pressing member can apply a pressing force that is distributed substantially uniformly to the sheet without being affected by the remaining number and thickness of the sheet on the sheet mounting portion. For example, it is possible to prevent the paper pushed out from the pickup roller from being skewed (skewed) due to uneven pressure of the pressing member in the paper width direction.

According to a third aspect of the present invention, the pressing member is formed of a flexible material, and the pressing member presses the sheet against the sheet placing portion by its own weight and exerts a frictional force on the sheet. , The pressure of the pressing member against the paper can be prevented from fluctuating due to the remaining number of papers placed on the paper mounting portion and the thickness of the paper. Separation and feeding of sheets can be performed more reliably.

According to the paper transport mechanism of the present invention, the pressing member is formed by a brush in which a plurality of fibrous materials are bundled, and the brush applies the paper to the paper mounting table at the intermediate position. By applying pressure and applying a frictional force to the paper, the change in the repulsive force with respect to the deformation amount of the fibrous material is smaller than that of the pressing member made of a single elastic body. It is possible to suppress the fluctuation due to the remaining number of sheets and the thickness of the sheets placed on the stacking section, and it is possible to more reliably perform the separation and feeding of the sheets on the sheet stacking section. become.

According to the paper transport mechanism of the present invention, the pressing member is provided with a conductive portion made of a conductive material, and the conductive portion is grounded to a frame portion of the apparatus, a ground circuit or the like. It is a thing. According to this automatic paper transport apparatus, it is possible to prevent the paper from being triboelectrically charged and to generate an attraction force between the papers due to static electricity. It can be prevented from being sure.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an automatic document feeder according to an embodiment of the present invention.

FIG. 2 is a main part configuration diagram showing a scanner device provided with a conventional automatic document feeder.

FIG. 3 is an explanatory diagram of a transport operation in the scanner device shown in FIG.

4 is an explanatory diagram of a transport operation in the scanner device shown in FIG.

5 is an explanatory diagram of a transport operation in the scanner device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original mounting plate, 1a ... Original mounting surface, 2 ... Guide plate, 2a ... Guide surface, 3 ... Pressure holding lever, 4 ...
Pickup roller, 5 reverse roller, 6 feed roller, 7 white reference plate, 8 reading unit, 9, 10 transport roller pair, 11 holder, 12, 21
… Press-contact sheet.

Claims (5)

[Claims] A pressure holding member configured to press a bundle of sheets placed at a predetermined loading position on the sheet placement portion onto the sheet placement portion; and a pressure holding member placed at the loading position at the sheet placement portion. A pickup roller for pressing one or more sheets from the sheet bundle in the conveying direction by pressing against the sheet bundle in a part of a phase section during one rotation, and being disposed at a separation sheet feeding position downstream of the pickup roller; A reverse roller to which torque in the reverse rotation direction to the transport direction is transmitted via a torque transmission control member, and a roller pair arranged with the reverse roller arranged at the separation sheet feeding position to form a roller pair in the transport rotation direction. A feed roller for transmitting torque, and when one sheet is extruded to the separation feeding position by the pickup roller, the torque is transmitted by the torque from the feed roller. The control member idles and the reverse roller is driven to rotate in the transport rotation direction, one sheet is transported in the transport direction by the feed roller and the reverse roller, and the plurality of papers are moved to the separation sheet feeding position by the pickup roller. When the sheet is extruded, only one sheet of paper in contact with the feed roller is conveyed by the feed roller in the conveying direction, and the reverse sheet is reversely rotated by the reverse roller to push back the sheet toward the loading position. In the apparatus, the paper is pressed against a sheet in a region downstream of the pressing position by the pressure holding member in the conveying direction and in an area upstream of the separation sheet feeding position in the conveying direction, and the sheet is placed on the sheet An automatic sheet conveying device comprising a sheet-like pressure contact member for applying pressure on a sheet and applying a frictional force to a sheet. 2. The pressure contact member is formed of an elastic material,
2. The automatic sheet conveying device according to claim 1, wherein the pressing member presses the sheet against the sheet placing portion by an elastic force and applies a frictional force to the sheet. 3. The paper pressing device according to claim 1, wherein the pressing member is formed of a flexible material, and the pressing member applies a frictional force to the sheet while pressing the sheet against the sheet mounting portion by its own weight. Automatic paper transport device. 4. The paper pressing device according to claim 1, wherein the pressing member is formed by a brush in which a plurality of fibrous materials are bundled, and the brush presses the paper against the paper mounting portion and applies a frictional force to the paper. The automatic paper transport device according to the above. 5. The press-contact member is provided with a conductive portion made of a conductive material, and the conductive portion is brought into contact with a sheet on a sheet placing portion and grounded to a frame portion of the apparatus, a ground circuit, or the like. 5. The automatic sheet transporting device according to claim 1, wherein the automatic sheet transporting device comprises: