JP2002211788A - Belt conveying equipment and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the running stability of a conveying belt 309B by applying the tension of the conveying belt 309B in the direction of the centerline R2 of the conveying belt 309B. SOLUTION: This belt conveying equipment 305B comprises the conveying belt 309B for conveying a sheet and a plurality of pulleys 310B, 311B, and 312B for operating the conveyor belt 309B. The conveying belt 309B comprises a plurality of holes 313B, and the diameter of the plurality of holes 313B is smaller at the center part than at both end parts of the conveying belt 309B in the direction orthogonal to the conveying direction of the conveying belt 309B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt conveying device which prevents the belt from shifting during belt conveyance and achieves belt running stability.

[0002]

2. Description of the Related Art Conventionally, in order to stabilize the running of a belt conveying apparatus, curvatures have been provided to all of a plurality of pulleys supporting between belts to prevent the belt from being shifted. However,
In order to prevent the pulley from interfering with other devices arranged near the pulley, when the curvature of the pulley cannot be provided, or because the pulley is supported via many components,
For example, when the belt is slipped and the drive transmission between the pulleys is displaced, the belt is offset, and the belt end comes into contact with a component in the transport device, and the belt is scraped. There has been a problem that the shavings enter the conveying device and a device downstream thereof, causing malfunction of the device.

Here, a typical conventional example will be described in detail with reference to FIGS. As shown in FIG. 9, the image forming apparatus A includes a photosensitive drum unit 301A, a contact transfer charger 3
02A, a guide member 303A, a registration roller 304A, a belt transport device 305A, and a fixing device 306A for fixing the transferred image.

When the belt conveying device 305A is moved in the sheet conveying direction D
FIG. 10 shows a view from above (in the direction of arrow P1 in FIG. 9). As shown in FIG.
A transport belt 3 is driven by pulleys 310A, 311A and 312A.
09A is supported on the axis of the transport holder 314A and transported. The sheet is placed in the transfer holder 314A by the transfer belt 309.
A fan 315A for sucking the sheet A is provided, and the sheet is sucked through a plurality of suction holes 313A which are opened in the conveyance belt 309A and are uniform in size, thereby increasing the sheet conveyance force.

The pulley 310A has a shape such that its diameter gradually increases from both ends in the axial direction toward the center, and tension is applied to the conveyor belt 309A in the direction of the center line R1 of the conveyor belt 309A.

[0006]

However, the surface of the pulley 312A close to the contact transfer charger 302A cannot be provided with a curvature for avoiding contact with the contact transfer charger 302A. The pulley 310A and the pulley 312A are supported via many components. From these, the drive transmission between the pulleys is likely to be shifted, and as a result of the shift, as shown in FIG.
A, 311A and 312A are offset to one side in the axial direction. Then, the end 317A of the conveyor belt of the belt conveyor 305A contacts the end 317A of the conveyor belt and the conveyor ribs 338A on both sides thereof.
Can be sharpened. The generated shavings adhere to the image-formed sheet being conveyed, causing an image defect or causing the apparatus to operate when conveyed to a fixing device or the like disposed downstream in the sheet conveying direction D. It was a problem to cause defects.

It is an object of the present invention to realize the running stability of the conveyor belt by applying the tension of the conveyor belt to the center line direction of the conveyor belt.

[0008]

To achieve the above object, a typical configuration of the present invention is a belt transport device having a transport belt for transporting a sheet and a plurality of pulleys for operating the transport belt. The conveyance belt has a plurality of holes, and a diameter of the plurality of holes is smaller at a central portion than at both ends of the conveyance belt in a direction orthogonal to a conveyance direction of the conveyance belt.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) (Overall Configuration of Image Forming Apparatus) As shown in FIG. 1, an image forming apparatus main body S1 has an image reading means for reading image information on an upper part of the image forming apparatus main body S1. Scanner unit S2 as
And an image forming apparatus B as an image forming means below the scanner section S2, and a sheet feeding apparatus S3 below the image forming apparatus B. Hereinafter, each part will be described briefly.

The scanner unit S2 includes a scanning system light source 201, a platen glass 202, a document pressure plate 203 that can be opened and closed with respect to the image forming apparatus main body S1, a mirror 204, a lens 205, a light receiving element (photoelectric conversion element) 206, and a laser scanner 211. And an image processing unit (not shown).

In the scanner section S2, a platen glass
After pressing the document on the document 202 with the document pressing plate 203, the image reading operation is started. Then, the scanning light source 201 scans the lower part of the platen glass 202 in the direction of arrow a to read the image information of the original. The read image information of the document is
The image is processed by the image processing unit, converted into an electric signal, and transmitted to the laser scanner 211.

The sheet feeding device S3 includes the lower cassette 1a.
And the upper cassette 1b and one feed unit U
(U1, U2, U3). The feeding unit U1 is detachably attached to the image forming apparatus main body S1, and the feeding units U2 and U3 are detachably attached to the sheet feeding apparatus S3.

In the sheet feeding device S3, the sheets stored in the sheet cassette 1 (1a, 1b) are fed out by a pickup roller 3, and are fed one by one by a feed roller 4 and a retard roller 5 constituting a separating means. Separated and fed. After that, the image forming apparatus B is transported to the transport roller 105 so as to synchronize with the image forming operation.
To the registration roller 304B.

The image forming apparatus B includes a photosensitive drum unit 301B including a photosensitive drum 331B, a transfer charger 302B, a registration roller 304B, a laser scanner 211, an image writing optical system 113, a developing unit 114, and a charging unit (not shown). Have.

In the image forming apparatus B, a laser beam corresponding to image information emitted from the laser scanner 211 by the image writing optical system 113 is provided on the surface of the photosensitive drum 331B uniformly charged by the charger. The light is scanned to form a latent image on the photosensitive drum 331B. Photoconductor drum 3
The latent image formed on 31B is developed by the developing device 114 to form a toner image. This toner image is transferred to the sheet conveyed by the registration roller 304B in synchronization with the rotation of the photosensitive drum 331B at the nip between the photosensitive drum 331B and the transfer charger 302B.

The sheet on which the image has been formed is conveyed to a fixing device 306B by a belt conveying device 305B described later.
The fixing device 306B fixes the toner image on the sheet by heating and pressing. The sheet with the fixed toner image is
The sheet is discharged and stacked by a discharge roller 119 on a sorter 120 arranged outside the apparatus.

When images are formed on both sides of a sheet,
The sheet discharged from the fixing device 306B is supplied to a discharge roller 119.
Is sandwiched between. When the trailing edge of the sheet passes the branch point 207, the discharge roller 119 is rotated in the reverse direction, and the sheet is
It is transported on 21 and once placed. Thereafter, the sheet is conveyed by the conveying rollers 104 and 105, and the registration rollers 304B
And is inverted. After the image is formed on the inverted sheet in the same manner as described above, the sheet is discharged to the sorter 120 and stacked.

(Structure of Belt Conveying Apparatus) As shown in FIG. 2, the image forming apparatus B in the image forming apparatus main body S1 includes a photosensitive drum unit 301 around a belt conveying apparatus 305B.
B, a transfer charger 302B, a guide member 303B, a registration roller 304B, and a fixing device 306B for fixing the transferred image to a sheet.

The belt conveying device 305B is moved in the sheet conveying direction D.
FIG. 3 shows a view from above (in the direction of arrow P2 in FIG. 2). As shown in FIG. 3, the belt transport device 305B
Are supported by support portions Q1 and Q2 with respect to a front plate 307B and a rear plate 308B provided on both sides orthogonal to the sheet conveying direction D. The drive from the image forming apparatus main body S1 is transmitted from the gear 318B to the gear 319B, the gear 320B, and the gear 321B, and rotates the pulley 310B supported on the same shaft 322B as the gear 321B. The pulley 310B is provided with pulleys 311B and 312B having a bearing in the transfer holder 314B,
A transport belt 309B having a plurality of holes 313B is wound therearound, and the transport belt 309B is operated by driving transmitted to the pulley 310B.

The pulley 310B has a shape such that the diameter gradually increases from both ends in the axial direction toward the center.
The tension (T1, T2) applied to the conveyor belt 309B is always applied in the direction of the center line R2 of the conveyor belt 309B. On the other hand, the pulley 312B has no curvature because it is close to the transfer charger 302B for forming an image.

(Configuration of Conveying Belt) As shown in FIG.
The diameter of the plurality of holes 313B formed in the conveyance belt 309B in the present embodiment is configured to be gradually smaller at the center than at both ends in the direction orthogonal to the sheet conveyance direction D. Therefore, the vicinity of the center line R2 connecting the central portions is
The tension is higher than at the end 317B of the conveyor belt. For this reason, the tension is always applied to the center line R2, so that even if, for example, the conveyance belt 309B slips and the drive transmission between the pulleys is shifted, the conveyance belt 309B may be displaced.
The belt can run stably without being offset in the axial direction of the pulley.

Further, a fan 315B for adsorbing the sheet to the conveyance belt 309B is provided in the conveyance holder 314B, and a plurality of holes 313B serving as suction holes formed in the conveyance belt 309B.
The sheet conveying force is further increased by sucking the sheet through the.

As shown in FIG. 5, when the conveying belt 309B is larger than the sheet 325C to be conveyed, the plurality of holes 313B formed in the conveying belt 309B as described above have the , The opening ratio of the holes in the end region X1 of the conveying belt 309B where the sheet 325C is not in contact has a plurality of small diameter holes shown in FIG. In this case, the opening ratio of the holes in the end region X2 of the transport belt 309E is larger. For this reason, as shown in FIG. 7, the work amount of the fan during sheet conveyance can be suppressed, and the life of the fan can be extended.

(Second Embodiment) In the above embodiment, the diameter of the hole 313B of the conveyor belt 309B is changed to adjust the tension of the conveyor belt 309B.
As shown in FIG. 8, instead of the holes 313B, a conveyor belt 309D is used.
Is gradually increased from both ends in the direction orthogonal to the sheet conveying direction D toward the center. Accordingly, the tension near the center line R4 of the conveyor belt 309D is higher than that at the end 317D of the conveyor belt 309D. For this reason, the tension is always applied to the center line R4.
Even when the drive transmission between the pulleys is shifted due to the slippage of the 309D, the transport belt 309D can stably run without the belt being offset in the axial direction of the pulleys.

(Other Embodiments) In the first embodiment, the diameter of the hole 313B of the conveyor belt is changed, and in the second embodiment, the thickness T of the conveyor belt is gradually increased from both ends toward the center. Then, the tension near the center line of the conveyor belt was increased as compared with the end of the conveyor belt.However, the present invention is not limited to this. The diameter of the hole 313B of the conveyor belt was changed, and the thickness of the conveyor belt was further increased from both ends. By gradually increasing the thickness toward the center, the effect of increasing the tension in the vicinity of the center line of the conveyance belt as compared with the end of the conveyance belt is further enhanced.

In the above embodiment, an electrophotographic printer has been described as an example of an image forming apparatus. However, the present invention is not limited to this. For example, a belt conveying apparatus such as a copying machine, a facsimile apparatus, and an ink jet printer may be used. Is also good.

[0027]

As described above, according to the present invention, the diameter of the plurality of holes in the conveyor belt is larger at the center of the conveyor belt than at both ends in the direction orthogonal to the conveyance direction of the conveyor belt. Because it is characterized by being small, the vicinity of the center line connecting the central portion is higher in tension than the end of the conveyor belt, and the tension is always applied to the center line,
Even if, for example, the transport belt slips and the drive transmission between the pulleys shifts, the transport belt can run stably without the transport belt being offset in the axial direction of the pulley.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 2 is an explanatory diagram of the image forming apparatus according to the first embodiment.

FIG. 3 is an explanatory diagram of the belt transport device according to the first embodiment.

FIG. 4 is an explanatory diagram of the belt transport device according to the first embodiment.

FIG. 5 is an explanatory diagram of the belt transport device according to the first embodiment.

FIG. 6 is a diagram showing a conventional belt conveying device showing a comparison with the first embodiment.

FIG. 7 is a diagram illustrating a comparison of the workload between the first embodiment and a conventional fan.

FIG. 8 is an explanatory diagram of a belt conveyance device according to a second embodiment.

FIG. 9 is an explanatory diagram of a conventional image forming apparatus.

FIG. 10 is an explanatory diagram of a conventional belt transport device.

FIG. 11 is an explanatory diagram of a conventional belt conveyance device.

[Explanation of symbols]

 B: Image forming unit D: Sheet conveying direction Q1: Supporting unit Q2: Supporting unit R2: Center line R4: Center line S1: Image forming apparatus main body S2: Scanner unit S3: Sheet feeding device T: Thickness U: Feeding unit DESCRIPTION OF SYMBOLS 1 ... Sheet cassette 1a ... Lower cassette 1b ... Upper cassette 3 ... Pickup roller 4 ... Feed roller 104 ... Transport roller 105 ... Transport roller 113 ... Image writing optical system 114 ... Developing device 119 ... Discharge roller 120 ... Sorter 121 ... Double side tray 201: Scanning light source 202: Platen glass 203: Original platen 204: Mirror 205: Lens 206: Light receiving element 207: Branch point 211: Laser scanner 301B: Photoconductor drum unit 302B: Transfer charger 303B: Guide member 304B: Registration roller 305B ... Belt conveying device 306B ... Fixing device 307B ... Front plate 308B ... Rear plate 309B ... Conveying belt 309D ... Feeding belt 309E ... Conveying belt 310B ... Pulley 311B ... Pulley 312B ... Pulley 313B ... Hole 313C ... Hole 314B ... Transport holder 315B ... Fan 317B ... End 318B ... Transport rib 319B ... Gear 320B ... Gear 321B ... Gear 322B ... Shaft 323B ... Bearing 324B ... Bearing 325C ... Sheet 331B ... Photoconductor drum

Claims (5)

[Claims] 1. A belt transport device having a transport belt for transporting a sheet and a plurality of pulleys for operating the transport belt, wherein the transport belt has a plurality of holes, and a diameter of the plurality of holes is A belt conveying device, wherein a central portion is smaller than both end portions of the conveying belt in a direction orthogonal to a conveying direction of the conveying belt. 2. The belt conveying device according to claim 1, wherein a thickness of the conveying belt is thicker at a central portion than at both ends of the conveying belt in a direction orthogonal to a conveying direction of the conveying belt. Belt transport device. 3. The belt conveyance device according to claim 1, wherein the plurality of holes are suction holes for adsorbing a sheet. 4. A belt transport device having a transport belt for transporting a sheet and a plurality of pulleys for operating the transport belt, wherein the transport belt has a thickness in a direction orthogonal to a transport direction of the transport belt. A belt conveying device characterized in that a central portion is thicker than both end portions of the belt. 5. An image forming means which acts on an image carrier to form an image on a sheet, and an image forming means according to claim 1.
An image forming apparatus comprising: the belt conveying device according to any one of the preceding claims.