JP2001130771A - Sheet conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device not dirtying a sheet-like article as a conveying target over a long period. SOLUTION: This sheet conveying device provided with an endless belt having air suction holes on the front surface, at least two rolls for stretching and rotating the endless belt, a vacuum range including a part of the endless belt, and a suction means for depressurizing the inside of the vacuum range, and for sucking, holding and conveying the sheet-like article to the other part of the endless belt is provided with a cleaning means for cleaning the endless belt.

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 for conveying a sheet while sucking and holding a sheet on an endless belt surface.

[0002]

2. Description of the Related Art Heretofore, there has been widely known a sheet conveying apparatus which conveys a sheet while sucking and holding a sheet on an endless belt surface. For example, in an electrophotographic image forming apparatus, the recording sheet is transported from a transfer unit that transfers a toner image onto a recording sheet such as copy paper to a fixing unit that fixes the toner image on the recording sheet. Such a sheet conveying device may be used.

[0003]

However, in such a sheet conveying apparatus, the surface of the endless belt may become dirty, and consequently, the sheet to be conveyed may become dirty. For example, in the above-described example of the image forming apparatus, a small amount of toner in the apparatus adheres to and accumulates on the surface of the endless belt, which stains the recording sheet. In particular, when a recording sheet of a certain size is continuously conveyed and then a recording sheet of a larger size is conveyed, an area corresponding to the size difference on the large-sized recording sheet is easily stained. Further, the stain of the toner adhering to the recording sheet is fixed in a downstream fixing unit.

The present invention has been made in view of such problems, and an object of the present invention is to provide a sheet conveying apparatus which does not stain a sheet to be conveyed for a long time.

[0005]

In order to achieve the above object, the present invention provides an endless belt having an intake hole on its surface,
At least two rolls for stretching and rotating the endless belt, a vacuum area including a part of the endless belt, and suction means for reducing the pressure in the vacuum area, the surface of the endless belt A sheet conveying apparatus for suction-holding and conveying a sheet-like material, further comprising a cleaning means for cleaning the endless belt (claim 1).

Further, such a sheet conveying apparatus is applied to an electrophotographic image forming apparatus, and an endless belt having an intake hole on its surface, and at least two rolls for stretching and rotating the endless belt. A vacuum area including a part of the endless belt, and suction means for reducing the pressure in the vacuum area, suction-holding the recording sheet on the surface of the endless belt, and fixing the recording sheet from the transfer unit. The sheet conveying device of the image forming apparatus that conveys the endless belt to the sheet feeding unit includes a cleaning unit that cleans the endless belt.

FIG. 1A explains the concept of the present invention. Here, each roll rotates in the direction shown by the arrow. The endless belt rotates in the direction shown by the arrow with the rotation of the roll. The vacuum area including a part of the endless belt is decompressed by the suction means. Therefore, a sheet-like material (recording sheet) is suction-held on the surface of the endless belt by the suction holes provided on the surface of the endless belt, and is conveyed with the rotation of the endless belt. Further, in these inventions, since the cleaning means for cleaning the endless belt is provided, dirt does not accumulate on the endless belt, and it is possible to prevent the sheet-like material (recording sheet) from being stained.

The cleaning means may be, for example, a brush in which a resin brush is brought into contact with an endless belt. A brush made of resin is radially implanted with respect to a rotating shaft, and the brush is rotated while rotating the shaft. A member that comes into contact with the member can be appropriately adopted. Furthermore, in addition to those resin brushes, mix the brush with conductivity,
The conductive brush may be electrically grounded. Of course, the present invention is not limited to these configurations, and an appropriate cleaning unit can be appropriately selected in accordance with the characteristics of dirt attached to the endless belt.

In general, in order to maintain the effect of the cleaning means for a long period of time, it is necessary to hold the dirt cleaned by the cleaning means so as not to re-adhere to the endless belt or to discharge it to the outside. However, adopting such a configuration generally complicates the configuration of the sheet conveying device, increases the size thereof, and increases the cost.

Therefore, the present invention is based on the sheet conveying device according to claim 1 or 2, and the cleaning means is provided in the vacuum area (claim 3).

FIG. 1B illustrates the concept of the present invention. In the present invention, since the cleaning means is provided in the vacuum area, the cleaned dirt (such as toner) is sucked by the suction means and discharged to the outside. Therefore, the effect of the cleaning unit can be maintained for a long time without accumulation of dirt in the cleaning unit, and the cost can be prevented from being increased with a simple and space-saving configuration. . Preferably, a filter is provided in the exhaust path from the suction means to the exhaust port, and after the dirt sucked by the suction means is removed by the filter, the air is exhausted to the outside.

When the cleaning means is provided in the vacuum area as described above, it is preferable that the suction of the surrounding atmosphere by the suction means is not hindered in order to surely hold the sheet-like material (recording sheet) on the endless belt surface. preferable. Therefore, it is preferable that the cleaning means is provided at a place where the air flow is relatively small in the vacuum area. Here, taking into consideration the suction efficiency, the suction means is generally provided at a substantially central portion of the vacuum region in the endless upper belt moving direction.

Therefore, the present invention presupposes the sheet conveying apparatus according to claim 3, wherein the cleaning means is provided at an upstream end or a downstream end in the moving direction of the endless belt in the vacuum area. (Claim 4).

FIG. 1C explains the concept of the present invention. According to the present invention, the cleaning means is provided at the upstream end or the downstream end in the moving direction of the endless belt in the vacuum area (the upstream end in the drawing).
The sheet (recording sheet) can be reliably held on the endless belt surface without hindering the suction of the surrounding atmosphere by the suction means. The upstream end and the downstream end refer to, for example, the upstream and downstream regions when the vacuum region is divided into three equal parts in the moving direction of the endless belt, respectively.

[0015]

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view of an electrophotographic MFP (image forming apparatus) to which the sheet conveying apparatus according to the present embodiment is applied. Note that this multifunction peripheral has an image reading unit (not shown) and has both a function as a copier and a function as a laser beam printer. The configuration and operation of the laser beam printer will be described below.

This laser beam printer has four process units 10Y, 10M, 10C, which form toner images for each of black, yellow, magenta and cyan colors.
10K, and an intermediate transfer belt 20 on which a toner image is primarily transferred from each process unit. The toner image multiplex-transferred onto the intermediate transfer belt 20 is secondarily transferred onto a recording sheet P to form a full-color image. It is configured as follows.

Each of the process units 10Y, 10M, 10
C and 10Bk are arranged in parallel so that a toner image formed according to image information of each color is primarily transferred to the intermediate transfer belt 20. These four process units are arranged along the rotation direction of the intermediate transfer belt 20 so that yellow 10Y, magenta 10M, cyan 10C, and black 1Y.
They are arranged in the order of 0Bk.

Each process unit 10Bk, 10Y, 1
0M and 10C denote a photosensitive drum 11 as an image carrier;
A charging device 12 for charging the photosensitive drum 11 to a uniform background potential; and a ROS unit 1 for forming an electrostatic latent image on the photosensitive drum 11 by exposure to a laser beam Bm.
3, a developing device 14 for developing the electrostatic latent image on the photosensitive drum 11 to form a toner image, and electrostatically transferring the toner image on the photosensitive drum 11 onto the intermediate point copying belt 20 A primary transfer roll 15 and a photoconductor cleaner 16 for cleaning the surface of the photoconductor drum 11 after the transfer are provided.

The photoreceptor drum 11 has an organic photosensitive layer formed on a thin metal drum having a cylindrical shape. The charging device 12 includes a scorotron charger. The ROS unit 13 includes a semiconductor laser that emits a laser beam Bm modulated according to image information of each color, and a polygon mirror that rotates at a high speed and scans the laser beam Bm along the axial direction of the photosensitive drum 11. , Its laser light B
After traveling along a predetermined path while being reflected by the mirror, m exposes the photosensitive drum 11 through the scanning window.

Each developing device 14 is filled with a mixture of toner of each color of black, yellow, magenta, and cyan, and a carrier obtained by coating a magnetic material with a semiconductive material. By friction between the toner and the carrier, the toner is negatively charged. The toner image is formed on the photosensitive drum 11 in accordance with the image information of each color.

The primary transfer roll 15 is provided on the photosensitive drum 11
The intermediate transfer belt 20 is disposed so as to sandwich the intermediate transfer belt 20 therebetween, and a predetermined transfer bias current is applied to the transfer roll 15 so that the photosensitive drum 11 and the transfer roll An electric field is formed between the intermediate transfer belt 15 and the toner image charged on the photosensitive drum 11 by the Coulomb force. Each of the primary transfer rolls 15 is configured by covering a metal shaft with a conductive foam rubber.

The intermediate transfer belt 20 is formed endless and has a pair of belt transport rolls 21, 22a to 22a.
c, 23, and while rotating in the direction of the arrow, the respective color process units 10Y, 10M, 10C, 10B
It is configured to receive the primary transfer of the toner image formed by k. The material of the intermediate transfer belt 20 is polyimide, and is imparted with conductivity by containing an appropriate amount of carbon black. It is necessary that the size is larger than the maximum print image size, and the circumference is preferably an integral multiple of the circumference of the photoconductor drum 11 from the viewpoint of preventing color misregistration of each color toner image.

A secondary transfer roll 30 is disposed at a position facing one belt transport roll 21 with the intermediate transfer belt 20 interposed therebetween, and the recording sheet P is pressed against the transfer roll 30 and the intermediate transfer belt. 20 to receive the secondary transfer of the toner image from the intermediate transfer belt 20. That is, the belt transport roll 21 functions as a backup roll of the transfer roll 30. Note that the transport roll 22b is also a drive roll, and the transport roll 23 is also a steering roll.

A cleaner 24 for the intermediate transfer belt 30 is disposed at a position facing the belt transport roll 22b so that toner remaining on the intermediate transfer belt 20 after the secondary transfer is removed from the intermediate transfer belt 20. It is configured.

On the other hand, a recording sheet tray 40 for accommodating a plurality of recording sheets P, a pickup roll 41 for taking out the recording sheets P one by one from the recording sheet tray 40, and A pair of transport rolls 42a to 42c for sequentially transporting, a pair of registration rolls 43 for starting transport at a predetermined timing, a sheet chute 44 for regulating a transport path of the recording sheet P, and a sheet transporting device for transporting the transferred recording sheet P to the fixing device 5. 6a, b
It has. Further, the fixing device 5 includes a heating roll 51 and a pressure roll 52.

When a full-color image is formed by the multifunction machine having the above-described configuration, first, each ROS unit 10 is operated by the process unit 10Y, 10M, 10C, and 10Bk in accordance with the image information of each color.
Is exposed at a predetermined timing to form an electrostatic latent image, and the latent image is developed, whereby each process unit 1
On the photoconductor drums 11 of 0Y, 10M, 10C, and 10Bk, toner images corresponding to image information are formed.

Each process unit 10Bk, 10Y, 1
The toner images formed at 0M and 10C are sequentially transferred to the rotating intermediate transfer belt 20, and a multi-toner image in which toner images of respective colors overlap is formed on the intermediate transfer belt 20.

On the other hand, the recording sheet P is fed out of the paper feed cassette 40 at a predetermined timing, passes through a pickup roll 41 and a pair of transport rolls 42a to 42c, and a toner image primarily transferred onto the intermediate transfer belt 20 is secondarily transferred. At the timing of reaching the position, the registration roll pair 43 starts rotating and is inserted between the secondary transfer roll 30 and the intermediate transfer belt 20.

Thus, the multiple toner image on the intermediate transfer belt 20 is secondarily transferred to the recording sheet P. Then, the recording sheet P on which the secondary transfer has been performed is transferred to the sheet conveying device 6a.
b, the toner image is conveyed to the fixing device 5, and the fixing device 5 fixes the toner image.
A full color image is completed on top.

Embodiment 1 By the way, the present invention relates to the sheet conveying devices 6a and 6b. Hereinafter, the structure and operation of the present invention will be described in more detail with reference to FIGS. 3 and 4 as embodiments. FIG. 3 (a)
5 is a plan view of the sheet conveying device 6a viewed from the arrow V in FIG. FIG. 3B is a front view of the sheet conveying device 6a viewed from the direction of arrow V in FIG. FIG. 4 (a)
Is a side sectional view of the sheet conveying device 6a as viewed from the side. FIG. 4B is a perspective view of the sheet conveying device 6a viewed from the direction of arrow V in FIG. 4A. Note that the sheet conveying devices 6a and 6b have the same configuration.

The sheet conveying device 6 includes an endless belt 60 (a to 60) having a plurality of intake holes 600 on its surface.
e) and stretching and rotating the endless belt 60 2
Rolls 61 and 62, a housing 63 forming a vacuum area including a part 60 (A) of the endless belt 60, a fan unit 64 (suction means) for reducing the pressure in the vacuum area, and a fan unit 64 And a duct 68 adjacent to.

A fixed brush 65 is provided at a downstream end in the moving direction of the endless belt 60 in a vacuum area formed by the housing 63 and a part 60 (A) of the endless belt 60. ing. This fixed brush 65
Is composed of a grounded metal pedestal 65a and a brush 65b implanted on the pedestal 65a. This brush 65b is made of a resin such as polypropylene, and mixes insulating fibers and such resin with carbon black or the like,
Fibers having a predetermined conductivity are mixed with each other.

The sheet conveying device 6a thus configured
Will be described separately for the sheet conveying operation and the belt cleaning operation.

First, the sheet conveying operation will be described. The fan in the fan unit 64 rotates, and the pressure in the vacuum area is reduced. When the pressure in the vacuum region is reduced, the suction holes 600 in the portion 60 (A) of the endless belt 60, the vacuum region, and the fan unit 64 are removed from the suction holes 600 in the surface 60 (B) of the endless belt 60. An airflow which reaches through the duct 68 is generated. The recording sheet P holding the unfixed full-color toner image on the surface 60 (B) of the endless belt 60 is suction-held by the suction effect of this air flow. On the other hand, the endless belt 60 rotates with the rotation of the rolls 61 and 62. As a result, with the rotation of the endless belt 60, the recording sheet P is conveyed while being suction-held on the surface 60 (B) of the endless belt 60.

Next, the belt cleaning operation will be described.
When the endless belt 60 rotates, dirt such as toner adhered to the endless belt 60 is removed by friction with the brush 65b in contact therewith. The dirt that has fallen is part of the endless belt 60 (A) due to the airflow described above.
Air intake hole 600, vacuum area, fan unit 6
4, it is discharged from the duct 68 and remains attached to the brush 65 b, stays in the vacuum area, and does not adhere to the endless belt 60 again. In particular, brush 6
Since a part of 5b is conductive and is grounded via a metal pedestal 65a, the brush 65b is not charged by friction and does not attract toner or the like.

Further, since the fixed brush 65 is disposed at the downstream end in the moving direction of the endless belt 60 in the vacuum area, the suction effect of the fan unit 64 is less likely to be weakened.

Further, the air flow containing the dirt discharged from the duct 68 is finally exhausted to the outside of the machine, but by providing a filter (not shown) at the exhaust port, it is possible to prevent the dirt from being discharged to the outside. It can also be prevented.

Embodiment 2 This embodiment is a modification of the first embodiment. Therefore, the configuration and operation will be described below with reference to FIG. 5 focusing on differences from the first embodiment. FIG. 5A is a side cross-sectional view of the sheet conveying device 6a as viewed from the side. FIG. 5 (b)
FIG. 5 is a perspective view of the sheet conveying device 6a viewed from the direction of arrow V in FIG.

The sheet conveying device 6 includes an endless belt 60 having a plurality of intake holes 600 on its surface, and two rolls 61 and 62 for stretching and rotating the endless belt 60.
And a housing 63 forming a vacuum area including a part 60 (A) of the endless belt 60, and a fan unit 64 (suction means) for reducing the pressure in the vacuum area
And a duct 68 adjacent to the fan unit 64.

A rotary brush 66 and a flicker bar are provided at a downstream end in the moving direction of the endless belt 60 in a vacuum area formed by the housing 63 and a part 60 (A) of the endless belt 60. 67 are provided. The rotating brush 66 has a metal shaft 66 grounded.
a and a brush 66b implanted on the shaft 66a. The brush 66b is made of a resin such as polypropylene or the like, and is made of a mixture of insulating fibers and such resin mixed with carbon black or the like and imparted a predetermined conductivity. Flicker bar 67
Is integrally formed with the housing 63 and is provided at a position where it contacts the brush 66b.

The sheet conveying device 6a thus configured
Will be described. Endless belt 6
When the rotation is zero, the friction with the brush 66b in contact therewith removes the dirt such as toner adhered to the endless belt 60. The fallen dirt is removed by the air holes 60 in the part 60 (A) of the endless belt 60 due to the above airflow.
0, the air is discharged from the duct 68 through the vacuum area and the fan unit 64, does not remain on the brush 66 b, stays in the vacuum area, and does not adhere to the endless belt 60.

In particular, since a part of the brush 66b is conductive and is grounded via the metal shaft 66a, the brush 66b is not charged by friction and attracts toner and the like. Further, dirt such as toner slightly adhering to the brush 66b is shaken off by the impact when the brush 66b collides with the flicker bar 67.

Further, since the rotating brush 66 is provided at the downstream end of the endless belt 60 in the moving direction in the vacuum area, the suction effect of the fan unit 64 is less likely to be reduced.

Further, the air flow containing the dirt discharged from the duct 68 is finally exhausted outside the machine, but by providing a filter (not shown) at the exhaust port, it is possible to prevent the dirt from being discharged to the outside. It can also be prevented.

[0045]

As described above in detail, according to the present invention, it is possible to provide a sheet conveying apparatus which does not contaminate a sheet to be conveyed for a long period of time.

[Brief description of the drawings]

FIG. 1 illustrates the concept of the present invention.

FIG. 2 is a schematic cross-sectional view of an image forming apparatus to which the sheet conveying device according to the present invention is applied.

FIG. 3 is a plan view and a front view of the sheet conveying apparatus according to the present invention.

FIG. 4 is a side view and a perspective view of the sheet conveying apparatus according to the first embodiment of the present invention.

FIG. 5 is a side view and a perspective view of a sheet conveying device according to a second embodiment of the present invention.

[Explanation of symbols]

Reference numeral 30: transfer roll, 5: fixing device, 6a, 6b: sheet conveying device, 60: endless belt, 600: intake hole, 6
1, 62 roll, 63 housing, 64 fan unit, 65 fixed brush, 66 rotating brush, 67
Flicker bar

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takashi Kawabata 2274 Hongo, Ebina-shi, Kanagawa, Fuji Xerox Co., Ltd. (72) Inventor Naoto Yoshino 2274 Hongo, Ebina-shi, Kanagawa, Fuji Xerox Co., Ltd. Inside Ebina Works (72) Inventor Tatsuya Soga 2274 Hongo, Ebina-shi, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor Keiji Yamamoto 2274 Hongo, Ebina-shi, Kanagawa Prefecture, Fuji Xerox Co., Ltd. 72) Inventor Nobuyoshi Komatsu 2274 Hongo, Ebina-shi, Kanagawa, Fuji Xerox Co., Ltd.Ebina Business (72) Inventor Norio Hokari 2274 Hongo, Ebina-shi, Kanagawa Pref., Fuji Xerox Co., Ltd. Naoto Nishi, Ebina City, Kanagawa Prefecture 2274 Hongo, Fuji Xerox Co., Ltd. Ebina Office F-term (reference) 3F049 AA10 BA04 DA03 LA07 LB03 3F101 AB01 AB06 AB11 LA07 LB03

Claims (4)

[Claims] 1. An endless belt having an intake hole on its surface,
At least two rolls for stretching and rotating the endless belt, a vacuum area including a part of the endless belt, and suction means for reducing the pressure in the vacuum area, the surface of the endless belt A sheet conveying apparatus for suction-holding and conveying a sheet-like material, comprising a cleaning means for cleaning the endless belt. 2. An endless belt having an intake hole on its surface,
At least two rolls for stretching and rotating the endless belt, a vacuum area including a part of the endless belt, and suction means for reducing the pressure in the vacuum area, the surface of the endless belt A sheet conveying device of an image forming apparatus for sucking and holding a recording sheet and conveying the recording sheet from a transfer section to a fixing section, wherein the sheet conveying apparatus includes a cleaning unit for cleaning the endless belt. 3. The sheet conveying device according to claim 1, wherein the cleaning unit is provided in the vacuum area. 4. The sheet conveying apparatus according to claim 3, wherein the cleaning unit is provided at an upstream end or a downstream end in a moving direction of the endless belt in the vacuum area.