JP2002211777A - Sheet conveyance device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defective sheet conveyance due to wear or the like of a pickup roller when picking up a sheet material from a sheet loading tray by friction of the pickup roller. SOLUTION: In this sheet conveyance device having sheet feeding means 4 and 8 feeding the sheet material 2 from a sheet loading part 1 to a conveyance path, the sheet feeding means are composed so as to attract the sheet material by electrostatic attraction force and drive feeding to the conveyance path. A separating means 9 is provided separating other sheet materials by electrostatic attraction force from a conveyance target sheet material of a plurality of sheet materials fed by the sheet feeding means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus suitable for use in a sheet feeding section of an image forming apparatus such as a laser beam printer, a copying machine, a facsimile, and the like.

[0002]

2. Description of the Related Art As an example of such an image forming apparatus,
The configuration and operation of the laser beam printer will be described below.

As shown in FIG. 7, the laser beam printer has a laser light emitting section 23 which emits light in accordance with image information. A laser light image is formed on the photosensitive drum 24 from the light emitting section 23 based on the image information. Irradiation forms a latent image, and a toner image is formed by attaching toner to the latent image.

In synchronization with the formation of the toner image,
The pickup roller 36 is pressed against the sheet material 2 stacked on the sheet feeding cassette 1,
Is rotated to apply a conveying force to the sheet material 2, and the sheet material 2 is separated into one sheet by the separation slope 9, and the conveying roller pair 2 is separated.
6. The sheet is reversed and conveyed by the pair of registration rollers 27 and the like.

Thereafter, in the image forming unit formed as a process cartridge 28, the toner image formed on the photosensitive drum 24 is transferred to the sheet material 2 by applying a voltage to the transfer roller 25.

Further, while the sheet material 2 after the transfer of the toner image is guided by the guide member 29, the transfer toner image is transferred to the sheet material 2 by a fixing unit 30 having a heater (not shown).
To be established.

The sheet material 2 having the toner image fixed thereon is conveyed by discharge roller pairs 31, 32, 33,
4 to a paper discharge unit 35

[0008]

However, in the pickup section (sheet feeding section) of the sheet material from the cassette in the image forming apparatus as described above, the removal of the sheet material is determined by the friction coefficient μ of the surface of the pickup roller 36. I rely on you. For this reason, if the friction coefficient μ of the surface of the roller 36 decreases due to wear of the roller 36, adhesion of paper powder to the surface, or the like, it becomes impossible to take out and transport from the cassette,
There is a problem that sheet conveyance failure occurs.

[0009]

In order to solve the above-mentioned problems, the present invention provides a sheet conveying apparatus having a sheet feeding means for feeding a sheet material from a sheet stacking section to a conveying path. The sheet material is adsorbed by the electroadhesive force to drive the supply to the transport path.

As a result, it is possible to reliably prevent the occurrence of defective sheet conveyance due to the wear of the pickup roller or the adhesion of paper powder to the surface, as in the conventional case, and to stably convey the sheet. Become.

According to a second aspect of the present invention, in a sheet transporting apparatus having a sheet supplying means for supplying a sheet material from a sheet stacking section to a transporting path, a plurality of sheet materials supplied and driven by the sheet supplying means are provided. Separating means for separating another sheet material from the sheet material to be conveyed by electrostatic attraction force is provided.

Thus, even when a plurality of sheet materials are driven to be fed toward the conveyance path in a state of being superposed on the sheet mounting table by the sheet feeding means, the sheet materials which are not conveyed by using the electrostatic attraction force. Can be reliably separated from one sheet material to be conveyed.

In the first aspect of the present invention, in order to surely separate the sheet material adsorbed by the sheet supply means and to smoothly carry out the subsequent sheet conveyance, a separation guide means for separating the sheet member from the sheet driving means. May be provided.

Further, by providing a static elimination means for eliminating the charge of the sheet material sent to the transport path, or by providing a static elimination means for eliminating the charge of the sheet material on the sheet stacking portion, unnecessary charge of the sheet material is provided. Inconvenience may be prevented.

Further, the sheet supply means is configured to attract and feed the sheet material from the sheet stacking section to a portion provided in the transport path for reversing and transporting the sheet material, so that the sheet material is slipped during the reversal. May be suppressed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 4 show a laser beam printer (image forming apparatus) provided with a sheet conveying device according to a first embodiment of the present invention. The configuration of the laser beam printer according to the present embodiment other than the sheet material pickup unit (paper feed unit) is substantially the same as that of the printer described with reference to FIG. And replace it with the description.

In FIG. 1, reference numeral 1 denotes a paper feed cassette;
Here, a plurality of transfer sheet materials 2 as recording media are placed in a stacked state. The sheet material 2 in the cassette 1 is urged upward by the middle plate 3.

Reference numeral 4 denotes an endless belt made of an insulator. The driving roller 5 is disposed above the separating slope 9 and the driven roller 6 is disposed above the cassette 1.
Driven roller 7 disposed at a position facing separation slope 9
And the rotation of the drive roller 5 causes the arrow A
It is circulated in the direction.

Reference numeral 8 denotes a charger, which charges the endless belt 4. The endless belt 4, the driving roller 5, the driven rollers 6, 7, and the charger 8 constitute a sheet supply unit described in claims.

In the printer main body (housing), starting from the separation slope 9 close to the paper feed cassette 1, a first reversing conveyance path 26a around which the conveyance roller pair 26 is disposed, a registration roller pair 27, Body drum 24 and transfer roller 2
5, a conveyance path is formed to be connected to the paper discharge unit 35 via the image forming unit provided with the fixing unit 30 and the second reverse conveyance path 34.

Further, as will be described later, when a plurality of sheet materials 2 are taken out of the cassette 1 by the electrostatic attraction force of the endless belt 4, the separating slope (separating means) 9 is used. Sheet material 2 directly adsorbed on
In order to separate another sheet material 2 ′ from the endless belt 4, the sheet material 2 ′ is formed so as to be inclined with respect to the direction (horizontal direction) of taking out the endless belt 4 from the inside of the cassette 1, It is configured to be charged.

Reference numerals 10 and 37 denote static elimination brushes, which are provided in the first reversing conveyance path 26a and the sheet feeding cassette 1, respectively, and perform static elimination of the sheet material 2.

Further, in FIGS. 2 to 4, reference numeral 11 denotes separation guides provided on both side ends of the endless belt 4.

Next, the operation of the printer configured as described above will be described. The sheet material 2 that has been neutralized in advance by the neutralization brush 37 provided in the cassette 1 is pressed against the endless belt 4 by the upward urging force of the middle plate 3.

Since the endless belt 4 is charged by the charger 8, the sheet material 2 is attracted by its electrostatic attraction force. Then, the sheet material 2 adsorbed on the endless belt 4
Is taken out of the cassette 1 by the driving of the endless belt 4 by the rotation of the driving roller 5, and is driven toward the separation slope 9 of the transport path.

Here, there is a case where the plurality of sheet materials 2 are sucked in an overlapping state by the electrostatic attraction force of the endless belt 4, and are driven toward the separating slope 9 of the transport path.
In this embodiment, when the sheet material 2 is conveyed to the position of the driven roller 7 (that is, the position where the sheet material 2 is bent and driven by the endless belt 4), as shown in FIG. The sheet material 2 to be attracted and driven by the endless belt 4 due to the resistance to bending of the sheet material 2 and the reverse bias (electrostatic attraction force) applied to the separating slope 9 (the uppermost sheet material) Remains on the endless belt 4, and the other sheet material 2 ′ separates from the endless belt 4.

Thereafter, the rear end of the sheet material 2 is
When the sheet material 2 is driven to the position where the leading end of the sheet material 2 is opposed to the drive roller 5, the sheet material 2 slides on the separation guide 11 as shown in FIG. The sheet material 2 is detached from the belt 4, and the subsequent sheet conveyance is smoothly performed.

Then, in order to stably transfer the behavior of the sheet material 2 during transfer and transfer of the toner image, the charge is removed by the charge removing brush 10, and thereafter, the image forming unit, the fixing unit 30 and the sheet discharging unit 35 are discharged. Conveyed.

As described above, according to the present embodiment, the sheet material 2 is not affected by the friction coefficient μ of the surface of the pickup roller as in the prior art, but by the electrostatic attraction force determined by the charging amount of the endless belt 4 by the charger 7. To supply and drive
A conveyance failure does not occur due to abrasion of the roller, adhesion of paper powder to the roller surface, and the like, and stable sheet conveyance can be reliably performed.

(Second Embodiment) FIGS. 5 and 6 show a laser beam printer (image forming apparatus) provided with a sheet conveying device according to a second embodiment of the present invention. The configuration of the laser beam printer according to the present embodiment other than the sheet material pickup unit is substantially the same as that of the printer described with reference to FIG. 7, and thus the same reference numerals are given to the same components, and description will be omitted. .

In FIGS. 5 and 6, reference numeral 12 denotes an endless belt made of an insulator, and a driving roller 13 disposed at a curved portion of the first reversing conveyance path 20a and a driven roller disposed above the cassette 1. Roller 14 and separation slope 1
8 is wound around a driven roller 15 and an auxiliary roller 16 disposed at a position opposed to the auxiliary roller 8. This endless belt 1
2 is circulated in the direction of arrow B by the drive roller 13. The endless belt 12 is charged by the charger 17.

The endless belt 12, the driving roller 13, the driven rollers 14, 15, the auxiliary roller 16, and the charger 17 constitute a sheet supply means as claimed in the claims.

In the printer body (housing), starting from the separation slope 18 close to the paper feed cassette 1, a first reversing conveyance path 20a around which the conveyance roller pair 20 is arranged, a registration roller pair 27, Image forming unit including the body drum 24 and the transfer roller 25, the fixing unit 30 and the second
A transport path connected to the paper discharge unit 35 via the reverse transport path 34 is formed.

The separating slope (separating means) 18 is directly attached to the endless belt 4 when a plurality of sheets 2 are taken out of the cassette 1 by the electrostatic attraction of the endless belt 4 as described later. Adsorbed one sheet material 2
In order to separate the other sheet material from the sheet material, the sheet material 2 is formed so as to be inclined with respect to the transport direction (horizontal direction) of taking out the sheet material 2 from the cassette 1 by the endless belt 4.

Reference numerals 19 and 37 denote static elimination brushes, which are provided in the first reversing conveyance path 20a between the driving roller 13 and the conveyance roller pair 20 and in the sheet feeding cassette 1, respectively. I do.

Reference numeral 21 denotes separation guides provided at both ends of the endless belt 4, as shown in FIG. 6, which is slightly more conveyed than the driven roller 15 and closer to the drive roller 13 than the endless belt 12. It overhangs the route side.

Next, the operation of the printer configured as described above will be described. The sheet material 2 which has been neutralized in advance by the neutralization brush 37 is pressed against the endless belt 12 by the upward biasing force of the middle plate 3.

Since the endless belt 12 is charged by the charger 17, the sheet material 2 is electrostatically attracted to the endless belt 12. The electrostatically attracted sheet material 2 is
The driving of the endless belt 12 by the rotation of the
It is taken out from the inside and driven toward the separation slope 18.

Here, even if a plurality of sheet materials 2 are attracted in a state of being overlapped by the electrostatic attraction force of the endless belt 12, the sheet material 2 is conveyed to a position where the leading end of the sheet material 2 slightly exceeds the position of the driven roller 15. Then, the sheet materials 2 slide with respect to the separation guide 21 and are separated from the endless belt 12 by the guide action.

Then, these sheet materials 2 are used as separation slopes 1.
When the sheet material 2 is further conveyed, the sheet material 2 (the uppermost sheet material) to be conveyed and driven by the endless belt 12 is again attracted to the endless belt 12 by one sheet. The sheet is separated from other sheet members (not shown) and driven to be conveyed.

The sheet material 2 conveyed to the position of the driven roller 13 by the endless belt 12 is reversely conveyed while being electrostatically attracted to the endless belt 12 in the first reverse conveying path 20a.

Thereafter, the endless belt 12 enters the lower side of the separation guide 22, so that the endless belt 12 is separated from the sheet material 2.

Then, in order to stabilize the behavior of the sheet material 2 during conveyance and the transfer of the toner image, the sheet material 2 is neutralized by the neutralizing brush 19 and is conveyed to the conveying roller pair 20, where the image forming unit and the fixing unit are fixed. The sheet is conveyed to the unit section 30 and the sheet discharge section 35.

As described above, in the present embodiment, similarly to the first embodiment, the sheet material 2 is supplied and driven by the electrostatic attraction force determined by the charging amount of the endless belt 12 by the charger 18, so that the stable operation is ensured. Since the sheet can be conveyed and the sheet material 2 is electrostatically attracted to the endless belt 12 until the sheet material 2 is reversed in the first reversing conveyance path 20a, the occurrence of slipping of the sheet material 2 at the time of reversal can be suppressed. Can be.

In each of the above embodiments, a laser beam printer has been described as an example. However, the present invention is not limited to this. For example, other image forming apparatuses such as a copying machine, a facsimile, a word processor, and a sheet It can also be used for various devices that transport materials.

[0046]

As described above, according to the first aspect of the present invention, the sheet material is sucked by the electrostatic attraction force of the sheet feeding means and the sheet is driven to be fed from the sheet stacking section to the conveying path. As described above, it is possible to reliably prevent the occurrence of sheet conveyance failure due to wear of the pickup roller, adhesion of paper powder to the surface, and the like, and to stably convey the sheet.

According to the second aspect of the present invention, even when a plurality of sheet materials are driven to be fed toward the transport path in a state of being overlapped from the sheet mounting table by the sheet feeding means,
The sheet material that is not the conveyance target can be reliably separated from the sheet material to be conveyed by using the electrostatic attraction force, and only the sheet material to be conveyed can be reliably conveyed and driven.

In the first aspect of the present invention, if a detachment guide means for detaching the sheet member from the sheet supply means is provided, the sheet material adsorbed by the sheet supply means is surely separated, and the subsequent sheet conveyance is smooth. Can be done.

Further, by providing a static elimination means for eliminating the charge of the sheet material sent to the conveying path, or by providing a static elimination means for eliminating the charge of the sheet material on the sheet stacking portion, unnecessary charge of the sheet material may be caused. Inconveniences (for example, behavior of the sheet material during conveyance and instability of image transfer in the image forming apparatus) can be prevented.

Further, if the sheet supply means is configured to attract and drive the sheet material from the sheet stacking section to a portion provided in the transport path for reversing and transporting the sheet material, the sheet material may be slipped during the reversal. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus according to a first embodiment of the invention.

FIG. 2 is a perspective view of a sheet material pickup unit in the image forming apparatus.

FIG. 3 is an enlarged view of the pickup unit.

FIG. 4 is an enlarged view of the pickup section.

FIG. 5 is a cross-sectional view illustrating an overall configuration of an image forming apparatus according to a second embodiment of the invention.

FIG. 6 is an enlarged view of a sheet material pickup unit in the image forming apparatus according to the second embodiment.

FIG. 7 is a cross-sectional view showing the overall configuration of a conventional laser beam printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cassette 2, 2 'sheet material 3 Intermediate plate 4, 12 Endless belt 5, 13 Drive roller 6, 7, 14, 15, 16 Follower roller 8, 17 Charger 9, 18 Separation slope 10, 19, 37 Static removal brush 11, 21, 22 Separation guide 20, 26 Transport roller pair 20a, 26a First reverse transport path 23 Laser light emitting unit 24 Photoconductor drum 25 Transfer roller 27 Registration roller pair 28 Process cartridge 29 Guide member 30 Fixing unit 31, 32, 33 Discharge roller pair 34 Second reverse transport path 35 Paper discharge unit 36 Pick-up roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B65H 29/54 B65H 29/54 F term (Reference) 3F053 AA06 AA12 AA26 LA02 LA05 LA07 LB03 3F101 AA04 LA02 LA05 LA07 LB03 3F343 FA02 FB02 FB03 FB04 FC01 GA01 GB01 GC01 GD01 JC06 JC17 JD08 JD13 JD30 KA04

Claims (12)

[Claims] 1. A sheet conveying apparatus having a sheet feeding means for feeding a sheet material from a sheet stacking section to a conveying path, wherein the sheet supplying means adsorbs the sheet material by an electrostatic attraction force and feeds the sheet material to the conveying path. A sheet transport device that performs a supply drive. 2. The sheet conveying apparatus according to claim 1, wherein said sheet supply means is constituted by using a charged endless belt. 3. The sheet according to claim 1, further comprising a separation unit configured to separate a sheet material to be conveyed from another sheet material among the plurality of sheet materials adsorbed by the sheet supply unit. Transport device. 4. The apparatus according to claim 3, wherein said separating means separates another sheet material from a sheet material to be conveyed out of the plurality of sheet materials sucked by said sheet feeding means by an electrostatic attraction force. 3. The sheet conveying device according to 1. 5. The sheet conveying apparatus according to claim 4, wherein the separation unit is provided to face a position where the sheet feeding unit bends and feeds the sheet material. 6. The sheet supply device according to claim 1, further comprising a separation guide unit that guides the sheet material that is sucked and supplied and driven by the sheet supply unit so as to be separated from the sheet supply unit. The sheet conveying device as described in the above. 7. The sheet conveying apparatus according to claim 1, further comprising a charge removing unit configured to remove a charge of the sheet material supplied to the transport path by the sheet supply unit. 8. The sheet conveying apparatus according to claim 1, further comprising a static eliminator configured to neutralize the sheet material on the sheet stacking unit. 9. The sheet feeding device according to claim 1, wherein the sheet feeding unit sucks and feeds the sheet material from the sheet stacking unit to a portion for reversing and conveying the sheet material provided in the conveyance path. 9. The sheet conveying device according to any one of 8. 10. A sheet conveying device having a sheet driving means for supplying a sheet material from a sheet stacking section to a conveying path, wherein a sheet material to be conveyed among a plurality of sheet materials supplied and driven by the sheet supplying means is provided. A sheet conveying device comprising a separation unit for separating another sheet material by electrostatic attraction. 11. The sheet conveying apparatus according to claim 10, wherein the separation unit is provided to face a position where the sheet feeding unit bends and feeds the sheet material. 12. An image forming apparatus comprising the sheet conveying device according to claim 1, wherein an image is formed on a sheet material conveyed by the sheet conveying device.