JP2570091Y2 - Paper transport device in electrostatic printing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device in an electrostatic printing apparatus for preparing a master plate by fixing a toner image on a photoreceptor by an electrophotographic method, and performing printing using the master plate.

[0002]

2. Description of the Related Art Conventionally, an electrostatic printing apparatus which prepares a master plate by fixing a toner image on a sheet-shaped photosensitive member by an electrophotographic method and performs electrostatic printing using the master plate is disclosed in Japanese Patent Laid-Open Publication No. No. 96972 and the like. This will be described with reference to FIGS.

As shown in FIG. 5, a photoreceptor device 2, an exposure optical system device 3, a paper feeding device 4, a fixing device 5, and the like are arranged in an electrostatic printing device main body 1. In the photoreceptor device 2, a pair of take-up rolls 8 are provided in the photoreceptor drum 6, and the photoreceptor sheet 7 can be fed to the surface of the photoreceptor drum 6 by rotating the take-up roll 8.

Around the photosensitive drum 6, a charge corotron 10, an overall exposure lamp 11, a flash fixing device 1
2, developing machine 13, transfer corotron 14, paper transport device 1
5 and so on are provided. The exposure optical system device 3 includes an exposure lamp 1
6, an original image on a platen glass 19 is irradiated and exposed on the photosensitive sheet 7 to form an electrostatic latent image. The sheet feeding device 4 includes an upper tray 20 and a lower tray 21, and feeds a sheet from one of these trays onto the photoreceptor sheet 7 via a sheet feeding device 22.

[0005] First, the electrostatic printing apparatus having the above-described structure is constructed as follows.
After charging the surface of the photoreceptor sheet 7 with the charge corotron 10 in the same manner as in a normal electrophotographic copying machine, the exposure optical system 3 irradiates and exposes the original image to form an electrostatic latent image. The image is developed with toner by the developing machine 13 to create an unfixed plate-making master. Next, the unfixed master plate is flash-fixed by the flash fixing device 12, and the toner image is fixed on the photosensitive sheet 7 to form a printing master plate.

At the time of printing, the printing plate-making master is charged by a charge corotron 10 and an entire-surface exposure lamp 11 is charged.
The toner image is formed again by the developing device 13 to form a toner image, and the toner image is transferred to a sheet by a transfer corotron 14. Then, the transferred sheet is transferred to a sheet conveying device 15. , Vacuum suction transfer device 23
And is conveyed to the fixing device 5 for fixing. Thereafter, by repeating this operation, a large number of sheets are printed using the fixed toner image formed on the photosensitive member sheet 7 as a printing master. When the printing is completed, the take-up roll 8 is driven to form a new photosensitive sheet. The body sheet 7 is fed to the surface of the photosensitive drum 6.

FIG. 6 is a diagram showing a specific configuration of the paper transport device 15 and the paper supply device 22. The sheet sent from the sheet tray is sent by a pair of transfer rolls 50 and 51 along a transfer path 54 formed by upper and lower guide plates 52 and 53. On the downstream side of the transport path 54, a registration roll 55 is provided.
6 are pressed against each other. When the registration roll 55 starts rotating in response to a sheet feed signal, the sheet is sequentially conveyed to the photosensitive sheet 7 along upper and lower chutes 57 and 58, and the toner image is transferred to the sheet by the transfer corotron 14.

[0008] One side of the sheet on which the toner image has been transferred rides on a peeling plate 59 provided at the rear end of the photosensitive drum 6. The peeling plate 59 is formed of a thin metal plate, and the upper end side is fixed to the main body side bracket 60, and the middle portion is curved along the outer peripheral surface of the photosensitive drum 6, and the curved portion is higher than the middle portion. A guide piece 61 that curves in the opposite direction is cut and raised. Then, the leading end of the sheet is guided by the guide piece 61 and is sequentially separated from the surface of the photosensitive drum 6, and is conveyed to the sheet conveying device 15.

The paper transport device 15 includes a first turn roll 62 rotated by a driving unit (not shown) and a second turn roll 65 rotated by a timing belt 63.
And a turn belt 66 which is rotated by being pressed against the two turn rolls 62 and 65. The first turn roll 62 is provided at a position corresponding to the guide piece 61 of the peeling plate 59, and the second turn roll 65 is provided at a position above the first turn roll 62 on the downstream side. The turn belt 66 is wound around three pulleys 67, 68, and 69 arranged at the apexes of the triangle, and is pressed against the outer peripheral surfaces of the two turn rolls 62 and 65 by its own tension.

The sheet guided by the guide piece 61 and sequentially peeled from the surface of the photosensitive drum 6 is provided with first and second turn rolls 62 and 65 and a turn belt 66.
And the conveyance direction is changed so as to be U-shaped, and further sent to the vacuum suction conveyance device 23 side.

[0011]

In the above-mentioned electrostatic printing apparatus, the supply, conveyance, and discharge of paper are
Since a higher speed is required than a normal copying machine or the like, and the photoconductor is a sheet, and various devices different from the normal copying machine need to be provided around the photoconductor drum 6, the paper The transport device 15 adopts a special configuration for transporting the paper to the photosensitive drum through a substantially U-shaped transport path.

However, in the above-mentioned conventional paper conveying apparatus, the first turn roll 62 and the turn belt 66
The paper is pulled by the shock when the paper is bitten by the pressure contact portion, and the paper in the transfer area is slightly floated, and there is a problem that a white spot occurs due to poor transfer.

There are various types of paper, such as small-sized cardboard such as postcards, large-sized cardboard, and thin paper. When an experiment was performed using the above-described conventional paper transport apparatus, FIG. As shown, guide rolls 70, 7 are coaxial with first and second turn rolls 62, 65, respectively.
In the transfer mechanism, there is a problem that a mismatch between the photosensitive drum and the paper feed occurs in the transfer unit, and smear (image distortion) occurs when a small cardboard such as a postcard is transported. As shown in FIG. 7B, the problem can be solved by eliminating the guide roll 71 on the second turn roll 65 side. However, when a large-sized thick paper is conveyed, the paper speed on the opposite side to the turn rolls 62 and 65 is reduced. This causes a problem that the image is shrunk in the transfer section due to a delay, and that when the thin paper is conveyed, the paper sags and wrinkles are generated.

SUMMARY OF THE INVENTION The present invention is directed to solving the above-mentioned problem, and an electrostatic printing apparatus capable of preventing a transfer failure by preventing a sheet in a transfer area from floating, and preventing an image defect from occurring regardless of the type of the sheet. It is an object of the present invention to provide a paper transport device.

[0015]

In order to achieve the above object, a paper transport device in an electrostatic printing apparatus according to the present invention is provided with a first rotatably provided adjacent to one side of a photosensitive drum.
A turn roll, a second turn roll rotatably provided adjacent to the first turn roll, and a turn belt rotatably provided in pressure contact with the first and second turn rolls. A paper transport device for transporting the paper to the photosensitive drum through a substantially U-shaped transport path, wherein an upper guide member and a lower guide member are provided at the entrance side of the pressure contact portion between the first turn roll and the turn belt. Is provided.

The first turn roll extends in the axial direction of the photosensitive drum, and the second turn roll has in the axial direction a fixed guide member smaller in diameter than the second turn roll; A fixed guide member having the same diameter as the turn roll may be provided. Further, the fixed guide member having the same diameter may be movable toward the first turn roll. Further, the ratio of the peripheral speed difference between the turn roll and the photosensitive drum with respect to the photosensitive drum is -0.24 to
0.06%, and the ratio of the peripheral speed difference between the registration roll and the photosensitive drum with respect to the photosensitive drum may be set to be 0.13 to 0.47%.

[0017]

In the present invention, when the conveyance direction is changed to a U-shape by being guided to the pressure contact portion between the first and second turn rolls and the turn belt, the pressure contact between the first turn roll and the turn belt is made. The sheet is pulled by a shock when the sheet is bitten by the portion, but this force acts on the lower guide member and does not act on the sheet in the transfer area.

In the case of transporting a cardboard having a small size such as a postcard, the first fixed guide member has a curved surface with a diameter smaller than that of the second turn roll.
Does not come into contact with the fixed guide member, and therefore, there is no occurrence of a mismatch between the photosensitive drum and the paper feed at the transfer section. Further, when a large-sized thick paper is transported, since the paper is transported along the second fixed guide member, the speed of the paper on the side opposite to the turn roll becomes slow, and the problem that the image is shrunk at the transfer unit. Can be solved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the transport device in the electrostatic printing apparatus of the present invention. FIG. 1 is a perspective view showing a main part of FIG. 2, and FIG. 2 is a side view. In the present invention, the configuration of the electrostatic printing apparatus described with reference to FIG. 5 is applied.

In FIGS. 1 and 2, a registration roll 55 is provided below the transfer corotron 14, and is pressed by a pinch roll 56. When the registration roll 55 starts rotating in response to a sheet feed signal, the sheet is sequentially conveyed to the photosensitive drum 6 along upper and lower chutes 57 and 58, and a toner image is transferred to the sheet in the transfer corotron 14.

One side of the sheet on which the toner image has been transferred rides on a peeling plate 59 provided at an inner end of the photosensitive drum 6. The peeling plate 59 is formed of a thin metal plate, and the upper end side is fixed to the main body side bracket 60, and the middle portion is curved along the outer peripheral surface of the photosensitive drum 6, and the curved portion is higher than the middle portion. A guide piece 61 that curves in the opposite direction is cut and raised. Then, the leading end of the sheet is guided by the guide piece 61 and is sequentially separated from the surface of the photosensitive drum 6, and is conveyed to the sheet conveying device 15.

The paper transport device 15 includes a first turn roll 31 rotated by a driving unit (not shown) and a second turn roll 32 rotated by a timing belt 30.
And a turn belt 36 that is rotated by being pressed against the turn rolls 31 and 32. The first turn roll 31 is provided at a position corresponding to the guide piece 61 of the peeling plate 59, and the second turn roll 32 is provided at a position above the first turn roll 31 on the downstream side. The turn belt 36 is wound around three pulleys 33, 34, and 35 disposed so as to be located at the vertices of a triangle, and is pressed against the outer peripheral surfaces of the two turn rolls 31 and 32 by its own tension.

A guide roll 3 having the same diameter as the first turn roll 31 is provided on the axially front side of the first turn roll 31.
1a is rotatably connected and extends in the width direction of the paper transport path. Further, a first fixed guide member 37 is provided coaxially with the second turn roll 32 on the axially front side.
, And a second fixed guide member 39 is provided. Second
The fixed guide member 39 has a curved surface of the same diameter as the second turn roll 32 and is arranged at a position for receiving a large-sized sheet. Further, the first fixed guide member 37 is
And has a curved surface with a diameter smaller than that of the second turn roll 32, and is disposed between the second turn roll 32 and the second fixed guide member 39. In the present embodiment, the cross-sectional shape of the fixed guide member is substantially semicircular, but may be circular, arcuate, or the like.

Further, a guide piece 61 of the peeling plate 59 is located at the entrance side of the pressure contact portion between the first turn roll 31 and the turn belt 36. The upper guide member 40 is sandwiched by the guide piece 61. And a lower guide member 41 are provided.

The operation of the present invention having the above configuration will be described. First, the upper guide member 40 and the lower guide member 4
1 will be described. The sheet guided by the guide piece 61 and sequentially separated from the surface of the photosensitive drum 6 is
It is guided to the pressure contact portion between the first and second turn rolls 31 and 32 and the turn belt 36, and the transport direction is changed so as to be U-shaped. At this time, the first turn roll 31
The paper is pulled by the shock when the paper is bitten by the pressure contact portion of the turn belt 36, and this force acts on the lower guide member 41 and does not act on the paper in the transfer area. The resulting transfer failure can be prevented. The lower guide member 41 causes the leading end of the sheet to abut on the pulley 35 of the turn belt 36, but this is prevented by the upper guide member 40, and the sheet is securely pressed against the first turn roll 31 and the turn belt 36. Section.

Next, the operation of the first and second fixed guide members 37 and 39 provided on the second turn roll 32 will be described. In the case of transporting a cardboard having a small size such as a postcard, the first fixed guide member 37 has a curved surface with a smaller diameter than the second turn roll 32, so that the paper is transferred to the first fixed guide member 37. Without contact,
Therefore, occurrence of smear (image distortion) can be prevented without causing a mismatch between the photosensitive drum and the paper feed in the transfer section. In the case of transporting thick paper having a large size, the paper is transported along the second fixed guide member 39, so that the paper speed on the opposite side to the turn rolls 31 and 32 is reduced, and the image is transferred to the transfer unit. The problem of shrinking can be solved. Further, in the case of thin paper, the slack of the paper is regulated by the presence of the first fixed guide member 37, so that generation of wrinkles can be prevented.

FIG. 3 is a side view showing another embodiment of the present invention. In this embodiment, a small-diameter first fixed guide member 37 provided on the side of the second turn roll 32 is arranged coaxially with the second turn roll 32, and the second fixed guide member 39 of the same diameter is provided. The axis is moved from the axis of the second turn roll 32 to the first turn roll 31 side. According to the present embodiment, when a large-sized thick paper is conveyed, the curvature of the paper on the second fixed guide member 39 side becomes larger than that on the turn roll 32 side, and the paper on the opposite side to the turn rolls 31 and 32 is formed. It is possible to solve the problem that the image is shrunk at the transfer section without the speed being delayed. Note that the moving distance of the second fixed guide member 39 may be adjustable.

FIG. 4 is a diagram showing the results of an experiment when thick paper is conveyed in the present invention. The horizontal axis represents the ratio of the peripheral speed difference between the turn roll and the photosensitive drum with respect to the photosensitive drum = [(turn roll peripheral speed). The vertical axis represents the ratio of the peripheral speed difference between the registration roll and the photosensitive drum with respect to the photosensitive drum = [(registration roller peripheral speed−photosensitive drum peripheral speed). ) / Photosensitive drum peripheral speed] (%). The peripheral speed of the registration roll 55 and the peripheral speed of the turn roll 31 are made slightly slower than the peripheral speed of the photosensitive drum 6 so that the photosensitive drum 6 and the registration roll 55
It has been known for a long time that a loop is formed between the sheet and the turn roll 31 so that the sheet can be easily tacked in the transfer area.

However, if the same method is used for thick paper, the tacking force due to the transfer electric field is weak, so that a tack failure occurs as shown at A in FIG. When the peripheral speed of the registration roll 55 is increased and the peripheral speed of the turn roll 31 is decreased, a loop of paper that should be created between the registration roll 55 and the photosensitive drum 6 is advanced to the turn roll 31 side, and the paper When the rear end comes out of the cashier roll 55,
The sheet is returned by the reaction force of the sheet loop between the photosensitive drum 6 and the turn roll 31, and the smear occurs as shown in the B section. Conversely, by lowering the peripheral speed of the cashier roll 55,
If the peripheral speed of the turn roll 31 is increased, when the trailing edge of the sheet comes out of the registration roll 55, the sheet is
As a result, a smear occurs as shown in a portion C. Further, if the peripheral speed of the registration roll 55 is set too high, there is a problem that the image is excessively stretched as shown in a portion D.

Therefore, the peripheral speed ratio of the turn roll to the photosensitive drum is -0.24 to 0.06%, and the peripheral speed ratio of the registration roll to the photosensitive drum is 0.13 to 0.47%.
It was found that the smear disappeared even when printing on thick paper if the setting was made such that.

[0031]

As is apparent from the above description, according to the present invention, when the conveying direction is changed to be U-shaped by being guided to the pressure contact portion between the first and second turn rolls and the turn belt. The sheet is pulled by a shock when the sheet is bitten by the pressure contact portion between the first turn roll and the turn belt. However, this force acts on the lower guide member and does not act on the sheet in the transfer area. This can prevent transfer failures caused by the transfer. The lower guide member prevents the leading end of the sheet from coming into contact with the pulley of the turn belt, but the upper guide member prevents the leading end of the sheet and ensures that the sheet is conveyed to the press contact portion between the first turn roll and the turn belt. it can.

In the case of transporting a cardboard having a small size such as a postcard, the first fixed guide member has a curved surface smaller in diameter than the second turn roll.
Therefore, occurrence of smear (image distortion) can be prevented without causing a mismatch between the photosensitive drum and the paper feed at the transfer section. Further, when a large-sized thick paper is transported, since the paper is transported along the second fixed guide member, the speed of the paper on the side opposite to the turn roll becomes slow, and the problem that the image is shrunk at the transfer unit. Can be solved. Further, in the case of thin paper, the slack of the paper is restricted by the presence of the first fixed guide member, and the generation of wrinkles can be prevented.

Therefore, it is possible to prevent the transfer failure by eliminating the floating of the sheet in the transfer area, and to prevent the occurrence of image defects regardless of the type of the sheet.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a transport device in the electrostatic printing device of the present invention.

FIG. 2 is a side view showing one embodiment of a transport device in the electrostatic printing device of the present invention.

FIG. 3 is a side view showing another embodiment of the present invention.

FIG. 4 is a diagram showing experimental results in the present invention.

FIG. 5 is a configuration diagram showing a conventional electrostatic printing apparatus.

FIG. 6 is a side view showing a conventional transport device.

FIG. 7 is a diagram for explaining the problem of the present invention.

[Explanation of symbols]

6 photoreceptor drum, 31 first turn roll, 32
Second turn roll 36: turn belt, 37: first fixed guide member 39: second fixed guide member, 40: upper guide member,
41 ... Lower guide member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/16 G03G 15/16

Claims (4)

(57) [Scope of request for utility model registration] A first turn roll rotatably provided adjacent to one side of the photosensitive drum; and a second turn roll rotatably provided adjacent to the first turn roll. And a turn belt rotatably provided in pressure contact with the first and second turn rolls, wherein the sheet is conveyed to the photosensitive drum through a substantially U-shaped conveyance path. A sheet transport device in an electrostatic printing apparatus, wherein an upper guide member and a lower guide member are disposed on the entrance side of a pressure contact portion between a first turn roll and a turn belt. 2. The first turn roll extends in the axial direction of the photosensitive drum, and in the axial direction of the second turn roll, a fixed guide member smaller in diameter than the second turn roll;
The paper transport device in the electrostatic printing apparatus according to claim 1, wherein a fixed guide member having the same diameter as the second turn roll is provided. 3. The sheet conveying device according to claim 2, wherein the fixed guide member having the same diameter is movable toward the first turn roll. 4. A ratio of a peripheral speed difference between a turn roll and a photosensitive drum with respect to the photosensitive drum is -0.24 to 0.06%.
The electrostatic device according to any one of claims 1 to 3, wherein a ratio of a peripheral speed difference between the registration roll and the photosensitive drum with respect to the photosensitive drum is set to be 0.13 to 0.47%. Paper transport device in a printing device.