JPH10139208A - Sheet conveying device and sheet processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the post card conveying performance in a sheet conveying device which conveys sheets having a centralized conveyance standard by using an endless conveying belt. SOLUTION: In a sheet conveying device, conveying belts 120,121 having a large belt width, which convey the sheet sucked under vacuum to a belt surface, are arranged on both sides of a conveying passage, while a post card conveying belt 140 having a small belt width, which conveys the sheet without sucking the sheet (under vacuum) to the belt surface, is arranged in the central part of the conveying passage. The conveying surface of the post card conveying belt 140 is located at a place higher than that of the conveying belts 120, 121. In addition, the belt width of the post card conveying belt 140 is smaller than the width of the post card. The post card conveying belt 140 conveys the post card, taking advantage of the frictional force produced between the belt surface and the post card.

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 provided in a sheet processing apparatus such as a copying machine, a printer, a facsimile, and the like. Here, the sheet processing apparatus is a general term for an apparatus that performs a predetermined process (for example, forming an image, reading an image, and the like) on sheets fed one by one.

[0002]

2. Description of the Related Art In a sheet processing apparatus such as a copying machine, a printer, and a facsimile, a sheet is usually nipped and conveyed using a pair of conveying rollers. However, the sheet is transported using an endless transport belt in an area where it is inconvenient to hold the sheet. An example is shown below.

FIG. 7 shows the overall structure of a conventional electrophotographic copying machine.

In this copying machine, an automatic document feeder (ADF) 10 provided at an upper part of the copying machine main body 100 is used.
1, the document is set on the document table 102 one by one.

The paper feed tray 10 of the automatic document feeder 101
Documents (not shown) loaded on document feeder 3
The document is fed onto the document table 102 one sheet at a time. The document fed onto the document table 102 is set at a predetermined position on the document table 102 by the transport belt 105. Immediately thereafter, the optical system 106 operates to read the image of the document on the document table 102. Then, the document whose image has been read on the document table 102 is discharged onto the discharge tray 107 by the transport belt 105.

The image read by the optical system 106, that is, the image light is projected onto the photosensitive drum 108 rotating clockwise. As a result, an electrostatic latent image is sequentially formed on the photosensitive drum 108, and the electrostatic latent image is visualized (toner image) by the toner supplied from the developing device 109.

In the copying machine main body 100 of the copying machine, there are provided two automatic sheet feeding units, a sheet feeding cassette 110 and a paper deck 111, and sheets S in one of the sheet feeding units are selectively provided. It is to be fed. The manual tray 112 is capable of manually feeding sheets one by one.

[0008] Paper cassette 110 or paper deck 1
11 or the sheet S fed from the manual feed tray 112 reaches the registration roller pair 113 in the rotation stopped state,
When the leading edge of the sheet abuts the nip of the pair of registration rollers 113 to form a predetermined amount of loop, the sheet stops moving. Thereby, the skew state of the sheet S is corrected.

The sheet S, for which the skew state has been corrected, is rotated between the photosensitive drum 108 and the transfer charger 114 by a pair of registration rollers 113 which starts rotating at the timing of aligning the position with the toner image on the photosensitive drum 108. It is sent to the intermediary transfer section. Then, the toner image on the photosensitive drum 108 is sequentially transferred to the sheet S passing through the transfer unit by the transfer charger 114.

The sheet S that has passed through the transfer section is charged by the separation charger 1
The sheet is peeled off from the photosensitive drum 108 by 15 and is conveyed to the fixing device 117 by a sheet conveying device 116A using an endless belt. The sheet S that has reached the fixing device 117 is heated and pressed while passing through the nip between the fixing roller 117a and the pressure roller 117b, so that the transfer toner image is fixed on the sheet surface.

The sheet S on which the toner image has been fixed in the fixing device 117 is discharged onto a discharge tray 119 outside the apparatus by a discharge roller pair 118.

In this copying machine, the sheet S having passed through the transfer section is transferred to a sheet conveying device 11 using an endless belt.
The reason why the toner image is conveyed to the fixing device 117 by 6A is to prevent the unfixed toner image transferred onto the sheet S from being rubbed.

FIGS. 8 and 9 show a sheet conveying device 116A.
The detailed configuration of is shown. FIG. 8 is a plan view and FIG.
Is a longitudinal side view.

The sheet conveying apparatus 116A has a pair of right and left conveying belts (endless rubber belts) 120 and 121 for conveying the sheet S on the basis of the center conveying. Each of the transport belts 120 and 121 is installed so as to surround the suction duct 122 which faces in a direction orthogonal to the sheet transport direction.

The transport belts 120 and 121 are provided with a driving pulley 123 installed on the downstream side of the suction duct 122,
It is wound around driven pulleys 124 and 125 installed on the upstream side of the suction duct 122. Drive pulley 1
Reference numeral 23 denotes a drive shaft 1 to which drive from a motor (not shown) is transmitted.
26. The driven pulleys 124 and 125 are fixed on rotatable driven shafts 127 and 128.

The suction duct 122 is provided with a fan (not shown). When the fan is driven, the pressure in the duct is reduced, and an air suction force is generated. Upper plate 1 of suction duct 122
An opening 130 for suction is formed in a portion covered by the 29 conveyor belts 120 and 121, and a number of holes 131 for suction are formed in the entire belt surface of each conveyor belt 120 and 121. Therefore, when an air suction force is generated in the suction duct 122, the sheet S on the transport belts 120 and 121 is attracted to the belt surfaces.

The upper plate 129 of the suction duct 122 plays a role of guiding the conveyance of the sheet S in a sheet passing area other than the conveyance belts 120 and 121.

When the sheet S is conveyed by the sheet conveying device 116A, the conveying belts 120 and 121 are driven in the sheet conveying direction, and the pressure in the suction duct 122 is reduced by driving a fan. Therefore, the sheet S on which the transfer of the toner image has been completed in the transfer section is transported by the transport belts 120 and
The toner is conveyed to the fixing device 117 while being attracted to the fixing device 117.

In this case, the sheet S separated from the photosensitive drum 108 by the separation charger 115 is
The sheet is guided by a sheet guide 132 provided on the transfer belts 120 and 121. Also, the conveyor belt 1
The sheet S that has been conveyed by the rollers 20 and 121 and has reached the fixing device 117 has the leading end of the sheet S at the fixing roller 117.
a guide 13 leading to the nip between a and the pressure roller 117b
3 Here, the sheet guide 132 is generally located at a position higher than the belt surfaces of the transport belts 120 and 121. This is because even a sheet whose tip is curled downward is smoothly transferred onto the belt surface without being shocked, and does not affect the toner image being transferred.

[0020]

However, in the case of the above-described conventional sheet conveying apparatus 116A, a highly rigid sheet such as a postcard is conveyed without being in close contact with the belt surface. Problems have arisen.

That is, when the distance between the photosensitive drum 108 and the fixing device 117 is shortened by downsizing the copying machine main body 100, the sheet conveying device 116A installed between the photosensitive drum 108 and the fixing device 117 Naturally, the size is reduced, and the length of the effective portion of the conveyor belts 120 and 121 for sheet conveyance is shorter than the length of the postcard. In this case, the postcard is conveyed by the conveyance belts 120 and 121 and, when the leading end reaches the entrance guide 133, stops in a bridge shape with the entrance guide 133 and the sheet guide 132 as fulcrums. This is because the postcard does not adhere to the belt surface. In the case of plain paper or the like, such a problem does not occur because the paper is conveyed in a state of being in close contact with the belt surface. This is not the case if the sheet is of a size (large size) that does not form a bridge with the entrance guide 133 and the sheet guide 132 as a fulcrum even if the sheet is a highly rigid sheet that is not in close contact with the belt surface.

As a method of solving the above-described postcard conveyance failure, (1) the belt surface is higher than the sheet guide 132, and (2) the belt surface is higher than the entrance guide 133. However, in the case of the method (1), a sheet having a curled downward end cannot be smoothly transferred to the belt surface, causing a shock.
In the case of the method (2), the sheet whose leading end is curled upward cannot be guided to the nip between the fixing roller 117a and the pressure roller 117b. Such a problem occurs,
Not preferred.

Accordingly, the present invention has been made in view of the above-described circumstances, and provides a sheet transport apparatus capable of reliably transporting a postcard (a sheet having a small transport direction size and high rigidity). Aim.

[0024]

SUMMARY OF THE INVENTION The present invention relates to a sheet conveying apparatus that conveys a sheet based on a center conveyance using an endless conveyance belt.

According to the present invention, in order to achieve the above object, a first conveyor belt having a large belt width for vacuum-adsorbing and conveying a sheet on a belt surface is arranged on both sides of a conveying path.
A second conveying belt having a small belt width for conveying the sheet without being vacuum-sucked to the belt surface is disposed at the center of the conveying path, and the conveying surface of the second conveying belt is set to the conveying surface of the first conveying belt. It is characterized in that it is arranged at a higher position than that of the first conveying belt, and that the first conveying belt and the second conveying belt are configured differently to generate the sheet material.

For example, the belt width of the second conveyor belt is smaller than the postcard width. Further, the second transport belt transports the sheet by a frictional force generated between the belt surface and the sheet.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIGS. 1 and 2 show the structure of a sheet conveying apparatus according to a first embodiment of the present invention. FIG. 1 is a plan view, and FIG. 2 is a vertical sectional side view.

The sheet conveying device 116B is provided in a copying machine shown in FIG. In describing the configuration of the present sheet transporting device 116B, the same members and the like as those of the above-described conventional sheet transporting device 116A are denoted by the same reference numerals, and descriptions of components that are structurally and functionally the same are omitted. .

The sheet conveying apparatus 116B is provided with a postcard conveying belt (second conveying belt) 140. The postcard transport belt 140 is provided at an intermediate portion between the transport belts (first transport belts) 120 and 121, that is, at a central portion of the transport path. FIG. 2 shows the postcard passing area by an imaginary line. The width of the postcard transport belt 140 is approximately one third of the width of the postcard.

The postcard transport belt 140 has a drive shaft 126.
The drive pulley 141 fixed above and the driven shaft 12
Driven pulleys 142, 14 fixed on
3 and is driven in the same direction at the same time as the transport belts 120 and 121. The conveyance surface (upper surface) of the postcard conveyance belt 140 is the conveyance belt 12
0, 121 is slightly higher than the conveying surface. Here, the transport surface is set at a high position by making the drive pulley 141 and the driven pulley 142 of the postcard transport belt 140 larger in diameter than the drive pulley 123 and the driven pulley 124 of the transport belts 120 and 121.

The belt surface of the postcard transport belt 140 is flat, and the postcard is transported by a frictional force generated between the postcard and the postcard. Therefore, the belt surface has a high coefficient of friction. Note that this postcard transport belt 140 is not provided with a hole for suction.

When the sheet S is conveyed by the sheet conveying device 116B, the conveying belts 120 and 121 and the postcard conveying belt 140 are driven in the sheet conveying direction, and the pressure in the suction duct 122 is reduced by driving a fan. Therefore, the sheet S on which the transfer of the toner image has been
Is transported to the fixing device 117 while being attracted to the transport belts 120 and 121. The postcard moving in the center of the conveyance path is conveyed by the postcard conveyance belt 140. In this case, since the conveying surface of the postcard conveying belt 140 is at a high position, even if the tip of the downwardly curled postcard reaches the entrance guide 133, the postcard is continuously conveyed by the postcard conveying belt 140 without forming a bridge shape. Is done. <Second Embodiment> FIG. 3 shows a configuration of a sheet conveying apparatus according to a second embodiment of the present invention.

In describing the structure of the sheet conveying device 116C, the same members and the like as those of the sheet conveying device 116B will be denoted by the same reference numerals, and those which do not change in structure and function will be described. Omitted.

The transport belt 1 of the sheet transport device 116C
A large number of ribs 150 and 151 are formed at predetermined intervals on the surface of each of the belts 20 and 121 and the postcard conveying belt 140 at a predetermined angle. FIG. 4A shows ribs 150 formed on the belt surfaces of the conveyor belts 120 and 121, and FIG.
(b) shows the rib 151 formed on the belt surface of the postcard conveying belt 140.

When the ribs 150 are provided on the belt surfaces of the conveyor belts 120 and 121, the sheet S
Adhesion is improved. In this case, the height (H1) of the rib 150 does not need to be so high, but the pitch (P1) of the rib 150 is preferably small.

When the rib 151 is provided on the belt surface of the postcard conveying belt 140, the rear end of the postcard is caught by the rib 151, and the conveying force is higher than when only the frictional force is applied. In this case, it is better that the height (H2) of the rib 151 is not too high, and it is better that the pitch (P2) of the rib 151 is large. <Third Embodiment> FIG. 5 shows a configuration of a sheet conveying apparatus according to a third embodiment of the present invention.

In describing the structure of the sheet conveying device 116D, the same members and the like as those of the sheet conveying device 116C will be denoted by the same reference numerals, and those having no structural or functional change will be described. Omitted.

As shown in FIG. 6, a large number of ribs 1 having a high height (H3) and a small pitch (P3) are provided on the belt surface of the postcard conveying belt 140 of the sheet conveying device 116D.
52 are formed. When the rib 152 is high in this way, a bending force is generated due to the bending of the belt, so that the conveying force is higher than when only the frictional force is applied. Further, by making the height (H3) of the rib 152 higher than the height (H1) of the rib 150 of the transport belts 120 and 121 (H1 <H3), the diameters of the driving pulley 141 and the driven pulley 142 need not be increased. The transport surface can also be at a high position.

[0039]

As described above, according to the sheet transport apparatus of the present invention, the second transport belt which does not vacuum-adsorb a sheet whose transport surface is higher than the first transport belt which vacuum-adsorbs and transports the sheet is provided. Since the postcard is conveyed by the conveyance belt, the postcard that is being conveyed does not stop moving.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a sheet conveying apparatus according to a first embodiment of the present invention.

FIG. 2 is a vertical side view showing a configuration of the sheet conveying apparatus.

FIG. 3 is a plan view illustrating a configuration of a sheet conveying apparatus according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional side view showing a configuration of a conveyance belt and a postcard conveyance belt of the sheet conveyance device.

FIG. 5 is a plan view illustrating a configuration of a sheet conveying apparatus according to a third embodiment of the present invention.

FIG. 6 is a vertical side view showing a configuration of a postcard conveying belt of the sheet conveying apparatus.

FIG. 7 is a longitudinal sectional side view showing the overall configuration of a conventional copier (sheet processing apparatus).

FIG. 8 is a plan view showing a configuration of a sheet conveying device provided in the copying machine.

FIG. 9 is a vertical sectional side view showing a configuration of the sheet conveying apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 Copier body (sheet processing apparatus body) 116B, 116C, 116D Sheet transport device 120, 121 Transport belt (first transport belt) 140 Postcard transport belt (second transport belt) 151, 152 Rib S sheet

Claims (8)

[Claims] 1. A sheet transporting apparatus for transporting a sheet based on a central transport using an endless transport belt, comprising: a first transport belt having a large belt width for vacuum-adsorbing and transporting a sheet to a belt surface; A second conveying belt having a small belt width, which is arranged on both sides, and conveys the sheet without being vacuum-sucked to the belt surface, is arranged at the center of the conveying path, and the conveying surface of the second conveying belt is the first conveying belt. A sheet conveying device arranged at a position higher than the conveying surface of the conveying belt. 2. The sheet conveying device according to claim 1, wherein a belt width of the second conveying belt is smaller than a postcard width. 3. The sheet conveying apparatus according to claim 1, wherein the second conveying belt conveys the sheet by a frictional force generated between the belt surface and the sheet. 4. A large number of low-height ribs, which are oriented in a direction perpendicular to a sheet conveying direction, are formed at a large pitch on a belt surface of the second conveying belt. The sheet conveying device according to claim 1. 5. A method according to claim 1, wherein a plurality of high ribs are formed at a small pitch on the belt surface of the second conveyor belt, the ribs being oriented in a direction perpendicular to a sheet conveying direction. The sheet conveying device according to claim 1. 6. The apparatus according to claim 1, wherein the second conveyor belt is formed of a rubber material having a high friction coefficient.
6. The sheet conveying device according to any one of items 1 to 5. 7. A large number of low-height ribs, which are oriented in a direction orthogonal to a sheet conveying direction, are formed at a small pitch on a belt surface of the first conveying belt. The sheet conveying device according to claim 1. 8. A sheet processing apparatus, wherein the sheet conveying apparatus according to claim 1 is installed in a part of a sheet conveying path in a sheet processing apparatus main body.