JP2863385B2 - Transfer device in electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device in an electrophotographic apparatus such as a copying machine and a printer.

[0002]

2. Description of the Related Art In a conventional full-color copying machine as an electrophotographic apparatus, usually, yellow, magenta, and cyan toner images are individually formed on a photoreceptor belt, and then they are temporarily formed on an intermediate transfer belt. Then, the toner images superimposed on the intermediate transfer belt are transferred onto a sheet supplied from a sheet feeding unit. After the paper is supplied from a paper supply unit provided with a paper supply cassette or the like, the paper is transported by a transport roller to a pair of registration rollers. At this time, the sheet is temporarily stopped by being nipped by the registration rollers, and after the leading ends thereof are aligned and bent, the sheet is conveyed to the transfer device at a predetermined timing.

In a transfer unit 24 shown in FIG. 6, in a transfer step, a transfer roller 27 and a photoreceptor belt 12 are in pressure contact with each other, and a sheet passes between the two to perform transfer.
When the transfer step is completed, the sheet is transported to the next fixing step. A transfer roller gear 41 is fixed to an end of the transfer roller 27, and the transfer roller gear 41 meshes with a drive gear 42. The drive gear 42 is also a gear to which the drive from the main body is input, and the rotation direction of the drive gear 42 is normally the “1” direction during driving. The driving gear 42 also meshes with a registration roller gear 44 fixed to an end of the lower registration roller 43.
An upper registration roller 45 is pressed against the registration roller 43 by a registration roller spring 45.

When the transfer roller 27 moves from the descending / separating position to the ascending pressure contact position, or during the transfer at the ascending pressure contact position, a driving force is transmitted from the main body side, and the driving gear 42 rotates in the "1" direction. Is completed, and the transfer roller 27 moves from the raised pressure contact position to the lowered / separated contact position, the transfer roller 27 is lowered by its own weight, and at this time, the driving force of the main body is not transmitted.

Accordingly, when the transfer roller 27 descends, the drive gear 42 rotates in the direction "2" in the opposite direction to the driving.

[0006]

In the conventional transfer position as described above, when the transfer process is completed, the transfer roller 27 tends to descend and separate from the ascending pressure contact position around the drive gear 42. When 27 drops, fulcrum gear 4
Since 2 is engaged with the transfer roller gear 27, the lower resist roller gear 44 is to be rotated. in this case,
As the structure of the registration roller portion, the lower registration roller 4
The upper registration roller 45 is pressed against both ends by registration roller springs 46 so that both registration rollers 43 and 45 are pressed against each other.

Accordingly, a load due to the pressure contact is applied to the registration roller gear 44, and the registration roller gear 44 is hardly rotated. When the rotation of the registration roller gear 44 is heavy, the rotation of the fulcrum gear 42 is similarly heavy. In this case, the transfer roller 27 does not lower sufficiently even when trying to lower and separate, or does not lower at all, leading to a problem at the time of the next transfer.

[0008]

SUMMARY OF THE INVENTION A transfer device in an electrophotographic apparatus according to the present invention has the following features.
In the transfer unit, a registration roller for supplying the image forming body with the leading edge of the paper supplied from the paper conveyance unit is pivotally mounted, and a pressure frame is pivotally mounted near the registration roller by a shaft of a driving gear. A transfer roller pressurizing the sheet and the image forming body to transfer the image onto the pressure frame; a drive roller gear meshing with a registration roller gear and a transfer roller gear; and a one-way clutch provided on the registration roller gear. It is characterized by becoming.

[0009]

According to the structure of the transfer device, when the transfer roller descends and separates about the driving gear, the driving gear and the registration roller meshing with the driving gear rotate, but the one-way clutch acts on the registration roller shaft. On the other hand, since the idle roller runs idle, the load of the registration roller is not transmitted to the drive gear, and the transfer roller can be lowered only by its own weight.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transfer device in an electrophotographic apparatus according to the present invention will be described below with reference to FIGS.

A full-color copying machine, which is an electrophotographic apparatus,
As shown in FIG. 1, an exposure optical system 2 for exposure is provided below a glass document table 1 on which a document 37 is placed. The exposure optical system 2 includes a light source lamp 2a for irradiating a document 37 placed on the document table 1 with light, and a plurality of light guides for guiding reflected light from the document 37 onto the photoconductor 3 as indicated by a dashed line. , An imaging lens 2c disposed on the optical path, and a color separation filter 2d having three primary color filters of red, green, and blue. On the optical axis of the exposure optical system 2, a drum-shaped photoconductor 3 made of an organic photoconductor (OPC) irradiated with a light source that has been exposed and scanned.
Are arranged. On the outer periphery of the photoconductor 3, a photoconductor 3
A charger 4 for charging the photosensitive member 3, a charge removing lamp 5 for removing charge from the photosensitive member 3, and a cleaning device 6 for removing toner remaining on the photosensitive member 3 are provided. Further, a developing tank 7 for black and white in a state of not contacting the photoconductor 3 is provided on the upper part thereof.
The color developing tanks 8, 9, and 10 are provided independently of each other. These color developing tanks 8, 9, and 10 contain yellow, magenta, and cyan color developers, respectively.

On the other hand, below the photoreceptor 3, an intermediate transfer device 11 is provided. The intermediate transfer device 11 is provided with an intermediate transfer belt 12 as an image forming body.
It is designed to be rotationally driven by 3a, 13b, 13c. The photoconductor 3 is pressed against a portion of the intermediate transfer belt 12 between the first roller 13a and the second roller 13b, and the toner image formed on the photoconductor 3 is transferred onto the intermediate transfer belt 12. It is supposed to. Further, a cleaner 14 for removing the toner remaining on the intermediate transfer belt 12 is disposed near the first roller 13a.

[0013] Paper feed cassettes 16 and 17 containing paper 15 and a paper feed tray 18 are provided at a position on the right side of the intermediate transfer device 11 in the figure.
Each is provided with a paper feed roller 19, 20, 21. Then, the paper 15 placed on the selected paper feed cassette 16, 17 or the paper feed tray 18 is supplied using the respective paper feed rollers 19, 20, 21. Further, conveyance rollers 22 and 23 as sheet conveyance means are provided near each of the paper supply rollers 19, 20 and 21, and the paper 15 supplied from any of the paper supply rollers 19, 20 and 21 is provided. The sheet is conveyed to a roller transfer device 24 disposed to the left of the sheet cassettes 16 and 17.

The roller transfer device 24 has a unit frame 25 as a transfer roller support, which will be described in detail later. The unit frame 25 has upper and lower registration rollers 26a and 26b and transfer units. A roller 27 is attached.

On the left side of the roller transfer device 24, a separation plate 28 for separating the paper 15 from the intermediate transfer belt 12 is provided.
9 and the end of the paper transport belt 29, the paper 15
Fixing device 30 internally provided with fixing roller 31 for fixing full-color toner image formed on
And a paper discharge roller 32 for discharging the paper 15 to the outside.

Here, the structure of the roller transfer device 24 will be described in detail with reference to FIGS.

The roller transfer device 24 has a shape as shown in FIG. 2, and is formed detachably from the main body of the full-color copying machine. First, with reference to FIG.
The main constituent members of the above will be described. The unit frame 25 of the roller transfer device 24 includes the transfer roller 27 and the upper side.
Lower registration rollers 26a and 26b are attached to the upper and lower registration rollers 26a and 26b, respectively.
Above 26b, a paper guide 36 for guiding the paper to the transport unit is provided. Further, on the right end side of the roller transfer device 24 in the drawing, an electromagnetic clutch 33 for operating the upper and lower registration rollers 26a and 26b so as to convey the paper 15 at a predetermined timing, and a spring clutch for raising and lowering the transfer roller 27. And a solenoid 35 that operates the spring clutch 34 to raise and lower the transfer roller 27 at a predetermined timing.

Next, the internal structure of the roller transfer device 24 will be described. FIG. 3 shows the transfer roller 2 of the roller transfer device 24.
Reference numeral 7 denotes a state in which the sheet is at the lowering / separating position with respect to the third roller 13c. First, the sheet is registered by the lower registration roller 26b and the upper registration roller 26a.
Align the leading edge of the paper. And the upper registration roller 26a
And the lower registration roller 26b are connected to a registration roller spring 46 that is suspended over the shaft of the upper registration roller 26a.
Are pressed against each other. At this time, the transfer roller 27
Is in the descending / separating position, but it is at the lowest position of the pressing cam 47 when the pressing lever 48 contacts and the pressing spring 49
The transfer roller 27 moves away from the photoreceptor belt 12 in a state where the interlocking pressing frame 50 is rotated and moved counterclockwise about the axis of the drive gear 42 in the drawing.

FIG. 4 shows a state in which the transfer roller 27 of the roller transfer device 24 is at the position of a pressure contact with the third roller 13c and is in the process of being transferred. In order to transfer the toner image, first, the toner image is moved from the position of the transfer roller 27 shown in FIG. 3 to the position shown in FIG. In order to press the transfer roller 27 against the pressure, the pressing cam 47
, The pressing lever 48 comes into contact at the highest position of the pressing cam 47, the pressing spring 49 is extended, and the interlocking pressing frame 50 is rotated about the axis of the driving gear 42. The transfer roller 27 is pressed against the photoreceptor belt 12 while rotating clockwise in FIG.
Since the blade 52 is fixed to the pressure frame 50, the positional relationship with the transfer roller 27 does not change.

In this embodiment, the roller transfer device 24
One-way clutch 53
The operation is described with reference to FIG. The transfer roller 27 shown in FIG. 5 is in the ascending pressure contact position and is in the same state as in FIG. 4, but during the transfer or when the driving force is transmitted from the main body, the pressing cam 47 is at the highest position. The pressing lever 48 comes into contact, the pressing spring 49 is extended, and the pressing frame 50 is rotated clockwise about the shaft 54 of the driving gear 42 to thereby move the transfer roller 2.
7 is a third roller 13c supporting the photosensitive belt 12.
Is pressed in through the photoreceptor belt 12.

The driving gear 42 receives the transmitted driving force,
The transfer roller 27 rotates in the “1” direction, and the driving force is transmitted to the transfer roller gear 41 meshed with the drive gear 42 to rotate the transfer roller 27 in the “1” direction. On the other hand, the driving force is transmitted to the roller gear 44 of the lower registration roller 26b meshed with the fulcrum gear 42, and at this time, the one-way clutch 53 is connected to the shaft 55 of the lower registration roller 26b.
The lower registration roller 26b is rotated in the “1” direction, and at the same time, the upper registration roller 26a pressed by the registration roller spring 46 and loaded is rotated in the “1” direction.

However, when the transfer step is completed, the driving force from the main body stops. Then, the transfer roller 27 starts descending and separating operation. First, the pressing cam 47 moves in the “2” direction about the shaft 51, and the pressing lever 48 also moves in the “2” direction about the shaft 56. However, the pressing spring 49 contracts and the urging force is weakened.
The transfer roller 27 is rotated in the “2” direction about the axis 54 of the transfer roller 27 by its own weight or the like.

The transfer roller 27 is lowered in the direction A by its own weight and the movement of the pressure frame 50. At this time, the transfer roller gear 41 does not rotate.
Since the drive gear 42 meshes with the drive gear 1, the drive gear 42 rotates in the “2” direction opposite to the direction in which the driving force is transmitted. Then, the registration roller gear 44 meshing with the driving gear 42 rotates in the “2” direction, and the one-way clutch 53 is opened at this time with the shaft 55 of the lower registration roller 26b. The lower registration roller 26b does not rotate. Therefore, the load due to the pressure contact between the upper and lower registration rollers 26a and 26b is not applied to the fulcrum gear 42.
, The drive gear 42 rotates in the “2” direction, and the transfer roller 27 also smoothly descends in the A direction together with the pressure frame 50.

[0024]

Since the transfer device of the present invention has the above-described structure, when the transfer process is completed and the transfer roller is lowered and separated, the one-way clutch provided on the input shaft of the registration roller acts on the drive gear. Since the load of the registration roller is not transmitted, there is no load for preventing the transfer roller from lowering, and the transfer roller can smoothly and reliably descend and contact only by the own weight of the transfer roller.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a simplified internal structure of a full-color copying machine according to an embodiment of the present invention.

FIG. 2 is a perspective view of a roller transfer device of the full-color copying machine.

FIG. 3 is a schematic diagram showing a state in which a transfer roller is lowered and separated in the roller transfer device.

FIG. 4 is a simplified schematic diagram showing an upper pressure contact state of a transfer roller in the roller transfer device.

FIG. 5 is a simplified schematic diagram illustrating the operation of the roller transfer device.

FIG. 6 is a schematic diagram illustrating the operation of a conventional roller transfer device.

[Explanation of symbols]

 Reference Signs List 3 Photoconductor 12 Intermediate transfer belt 15 Paper 24 Roller transfer device 26a Upper registration roller 26b Lower registration roller 27 Transfer roller 41 Transfer roller gear 42 Drive gear 44 Lower registration roller gear 46 Registration roller spring 50 Pressure frame 53 One-way clutch

Continuation of front page (72) Inventor Hideo Matsuda 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-5-188800 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G03G 15/16 G03G 15/00 510 G03G 15/00 550

Claims (1)

(57) [Claims] 1. A transfer unit, wherein a registration roller for supplying an image forming body with a leading edge of a sheet supplied from a sheet transport unit is pivotally mounted in a transfer unit and a pressing frame is moved close to the registration roller by a driving gear. A transfer roller that pivots on a shaft and presses the sheet and the image forming body to transfer the image onto the pressure frame is pivotally attached, and the driving roller meshes with a registration roller gear and a transfer roller gear. A transfer device in an electrophotographic apparatus, comprising a one-way clutch.