JPH0636027Y2 - Paper transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a sheet conveying device for an electrophotographic copying machine, and more specifically, it fixes the sheet by changing the sheet conveying direction by a reversing roll after transfer. The present invention relates to an improvement of a sheet conveying device of a type that conveys a sheet to a device.

[Problems to be solved by conventional technologies and devices]

In an electrophotographic copying machine, after a sheet is brought into contact with a toner image on a photoconductor to transfer the image onto the sheet, the sheet is separated from the photoconductor and sent to the next fixing step. This will be explained with reference to FIG. 4. The sheet P conveyed to the photoconductor 2 via the registration roll 1 has the toner image on the photoconductor transferred by the transfer corotron 3.
Then, the drive shaft 7 is separated from the photoconductor by the separating member 4.
A drive pulley 6 and an idler pulley 10 which are sandwiched between a reversing roll (not shown) provided at one end of the drive shaft and a reversing belt 5 to change the conveying direction thereof and which are provided at the other end of the drive shaft 7 and rotate coaxially with the reversing roll. It is guided to the fixing roll 9 by a conveying device having a plurality of endless conveying belts 8 which are hung between and.

Generally, in order to prevent the occurrence of image defects during transfer,
Peripheral speed v ₁ of registration roll and surface speed of photoconductor
It is desirable that the relationship of v ₁ = v ₂ = v ₃ = v ₄ be maintained between v ₂ and the peripheral speed v _{3 of the} reversing roll and the speed v _{4 of the} conveyor belt. Here, the speed v _{4 of the} conveyor belt is normally controlled between the drive pulley 6 and the idler pulley 10, but the drive pulley 6
The surface velocity v ₄ ′ of the portion of the belt that tends to be present tends to show a value of v ₄ <v ₄ ′ based on the thickness of the belt. Further, since the reversing roll 11 and the conveyor belt driving pulley 6 are coaxially rotating (see FIG. 6), their rotation speeds are the same, but the peripheral speed v ₃ of the reversing roll and the speed v _{4 of the} conveyor belt are If they are made equal (v ₃ = v ₄ ), generally the outer diameter d ₄ of the drive pulley including the thickness (Δd) of the conveyor belt becomes larger than the outer diameter d ₃ of the reversing roll (d ₃ <d ₄ ) There is a tendency (see FIG. 5). Therefore, when the paper P is pinched by the reversing roll 11 and the reversing belt 5 and reversed, as shown in FIG. 6, on the side not pinched by the paper reversing roll (the right side in FIG. 6), the paper is Due to its bending resistance, it bends with a large radius, but on the side sandwiched by the reversing rolls (the left side in FIG. 6), the paper is pressed by the reversing belt 5, so it bends with a small radius, Will come into strong contact with the portion of the conveyor belt hanging on the conveyor pulley 61 adjacent to the reversing roll. Since the outer diameter (d ₄ ) of this conveyor belt is larger than the outer diameter (d ₃ ) of the reversing roll and the surface speed is also large (v ₄ > v ₃ ) as described above, it is nipped by the reversing roll of the paper. The transport speed on the non-rotating side becomes higher than that on the side sandwiched by the reversing rolls, and in some cases it is lifted from the transport belt to change the posture of the paper, causing the paper to move between the surface speed of the photoconductor and the paper speed of the transfer section. Differences occur, and as a result, blurring, distortion, etc. occur in the transferred image. In particular,
The image part that is transferred at the moment when the leading edge of the paper that is most susceptible to paper speed fluctuations is sandwiched between the reversing roll and the reversing belt, or the moment when the trailing edge of the paper separates from the registration roll that controls the paper speed. There is a defect that image defects are likely to occur in the image portion transferred to the.

[Means / actions for solving problems]

According to the present invention, the above-mentioned problems are caused by separating the paper on which the toner image is transferred on the photoconductor from the photoconductor, and changing the conveyance direction of the paper by the reversing roll provided at one end of the drive shaft.
In an electrophotographic copying machine in which a sheet is conveyed to a fixing device and fixed by a sheet conveying device including a plurality of pulleys for an endless conveying belt attached to the drive shaft, counting from an endless conveying belt pulley adjacent to a reversing roll. At least one endless conveyor belt pulley is rotatably attached to the drive shaft, and the outer diameter of the conveyor belt plus the thickness of the conveyor belt is smaller than the outer diameter of the reversing roll. Will be resolved.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a side view of a sheet conveying apparatus according to the present invention, in which an endless conveying belt 8 is engaged over a drive pulley 6 and an idler pulley 12, and the belt is moving in the arrow direction. A suction box 13 sucks the sheet placed on the belt downward to prevent the sheet from falling off the belt during conveyance. 2 is a sectional view taken along the line AA of FIG. 1, in which 6,61,62,63 are drive pulleys,
Further, 11 is a reversing roll, which is attached to both ends of the drive shaft 7, and the reversing belt 5 is pressed against the reversing roll, and holds the side edge of the paper P. An endless conveyor belt pulley 61 adjacent to the reversing roll is rotatably attached to the drive shaft 7. However, the outer diameter of the pulley 61 added with the belt thickness (Δd) hung on this pulley is equal to that of the reversing roll. It is smaller than the outer diameter. The fixed rings 14 are fixed to the drive shaft on both sides of the pulley 61 so that the pulley 61 does not move left and right along the drive shaft. Other drive side pulleys (6
2, 63) and the idler pulley 12 are fixed to the drive shaft. The outer diameter of the drive pulley 6 is set so that the speed v _{4 of the} conveyor belt becomes equal to the peripheral speed v _{3 of the} reversing roll, and the outer diameters of the idler pulleys are all set equal. The belt hanging on 61 reverses the belt speed of the pulley 61, even though the outer diameter of the pulley 61 plus the belt thickness (Δd) is smaller than that of the belts of the other pulleys (62, 63). It can be equal to the peripheral speed of the roll. Therefore, when the paper is turned over, even if it comes into contact with the belt hanging on the conveyor belt drive pulley (61), the conveyance attitude of the paper does not change, image defects are prevented from occurring, and the speed of the conveyor belt increases. It is also possible to prevent the occurrence of a secondary obstacle such as a diagonal feeding of the sheet due to the change in

In the above description, when the curvature of the paper is large and only the belt of the first pulley (61) adjacent to the reversing roll comes into contact, the outer diameter of the pulley is reduced and the pulley is rotated around the drive shaft. It is freely installed to release the rotation difference with other pulleys (62, 63). However,
When the curvature of the paper is small and it comes in contact with the belt of the second pulley, the outer diameter of the second pulley is also made smaller and it is rotatably attached to the drive shaft to prevent the paper from being fed obliquely. it can. The same applies to the third and subsequent pulleys, if necessary.
However, since these pulleys are rotated by the idler pulleys that are rotated by the drive pulleys via the conveyor belt, it is necessary to limit the number of these pulleys so that the load on the drive pulleys is not unduly increased. The difference between the rotation speed of the endless conveyor belt pulley rotatably attached to the drive shaft and the drive pulley is generally small, so if the endless conveyor belt pulley is made of wear-resistant resin, the bearing I don't need it,
When it is made of metal, it must be rotatably attached to the drive shaft via a bearing.

In FIG. 2, the fixing ring 14 positions the endless conveyor belt pulley in the thrust direction. As shown in FIG. 3, it corresponds to the distance (s) between the left and right sides of the pulley 61. The protrusion 61 may be provided to position the pulley 61.

[Effect of device]

According to the present invention, among the plurality of endless conveyor belt pulleys of the sheet conveying device, at least one pulley counted from the pulleys adjacent to the reversing roll is rotatably mounted on the drive shaft, and the conveyor belt of the pulleys is Since the outer diameter with thickness added is smaller than the outer diameter of the reversing roll, the speed of the conveyor belt can be made equal to the peripheral speed of the reversing roll, no image defects occur during reversing, and the transfer paper is not skewed. It is possible to prevent the occurrence of secondary obstacles such as feeding.

[Brief description of drawings]

FIG. 1 is a side view of a sheet conveying device according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a view showing another example of the present invention, FIG. FIG. 5 and FIG. 6 are views for explaining a conventional sheet conveying device. 1 ... Registration roll, 2 ... Photoconductor, 3 ... Transfer corotron, 4 ... Separation member, 5 ... Reversing belt, 6,61,62,63 ... Drive pulley, 7 ... Drive shaft, 8 …… Endless conveyor belt, 9 …… Fixing roll, 10,12 …… Idler pulley, 11 …… Reverse roll, 13 …… Suction box, P …… Paper.

Claims (1)

[Scope of utility model registration request] 1. A sheet on which a toner image is transferred on a photoconductor is separated from the photoconductor, and the paper is conveyed by a reversing roll provided at one end of a drive shaft and a reversing belt provided so as to face the reversing roll. In an electrophotographic copying machine in which a sheet is conveyed to a fixing device and fixed by a sheet conveying device that changes direction and is attached to the drive shaft, the endless conveying belt that is adjacent to a reversing roll. Characterized in that at least one endless conveyor belt pulley counted from the conveyor pulley is rotatably attached to the drive shaft, and the outer diameter of the conveyor belt plus the thickness is smaller than the outer diameter of the reversing roll. Paper transport device.