JPH05224555A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To make the exchange cycle of a cleaning member longer by delaying the time when the cleaning member of a fixing unit is made to be in a toner- saturation state. CONSTITUTION:Side plates 33 are disposed to face oppositely on the upper part of a fixing roller 30, the supporting shafts 34 are supported by these side plates 33, respectively, and rocking levers 35 are provided so as to be freely turnable. Both ends of a cleaning roller 36 are attached so as to be freely turnable, on one ends of these rocking levers 35, respectively, to press the cleaning roller 36 on the fixing roller 30 by gravity, while one ends of turnable arms 37 are engaged with the other ends of the rocking levers 35, respectively. The other ends 37b of the turnable arms 37 are fixed on the rotary shafts 38a of rotary solenoids 38. The rotary solenoids 38 are provided at proper positions outside the fixing unit 21 and inside a device main body, and electrically connected with a control means 42 separating the cleaning roller 36 from the fixing roller 30 when a paper passes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet such as a laser printer, a laser copying machine, a laser facsimile, etc., by an electrophotographic system (a system for transferring an image formed on a photoconductor to a sheet such as paper or envelope for recording). Relates to an electrophotographic device for recording. More specifically, the present invention relates to an electrophotographic apparatus including a fixing device such as a fixing roller that presses a cleaning roller against a fixing member to clean offset toner attached to the fixing member.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a heater 1 is used in an electrophotographic apparatus of this type, for example, a laser printer.
In some cases, a roller-shaped pressure member 3 is pressed against a roller-shaped fixing member 2 having a built-in roller, and a fixing device that presses a cleaning roller 4 is rotatably driven by the fixing member 2.

Then, the sheet S after the image transfer is placed in a fixing device, and heat and pressure are applied between the fixing member 2 and the pressure member 3 to fix the transferred image on the sheet S, while the fixing member is fixed. The offset toner adhering to the surface of No. 2 was cleaned with a cleaning roller 4 to prevent the offset toner from solidifying and sticking to the surface of the fixing member over time.

[0004]

However, in the conventional laser printer, since the cleaning roller 4 is constantly pressed against the fixing member 2, the cleaning roller 4 is quickly saturated with the offset toner. There is a problem that the replacement cycle of the cleaning roller 4 is shortened.
Therefore, an object of the present invention is to delay the toner saturation state and prolong the cleaning roller replacement cycle.

[0005]

Therefore, what is stated in claim 1 is, for example, as shown in the following illustrated embodiment,
The sheet S after the image transfer is put in the fixing device 21, and the sheet S is passed between a fixing member such as the fixing roller 30 of the fixing device 21 and a pressure member such as a pressure roller 31 pressed against the fixing member. In the electrophotographic apparatus for fixing the transferred image of No. 1 and cleaning the offset toner adhering to the fixing member by pressing the cleaning roller 36 on the fixing member, the cleaning roller 36 is fixed to the fixing member.
And a control means 42 for separating the cleaning roller 36 from the fixing member when the paper is passed.

According to a second aspect of the present invention, for example, as shown in the following illustrated embodiment, in the electrophotographic apparatus according to the first aspect, the cleaning roller 36 is contacted and separated by a solenoid such as a rotary solenoid 38. It is characterized in that it is free and its solenoid is supported outside the fixing device 21.

[0007]

According to the first aspect of the invention, when the paper is passed,
The cleaning roller 36 is separated from the fixing member. And
The offset toner adhering to the surface of the fixing member adheres to the sheet S through which the offset toner passes, and the fixing member is self-cleaned. The cleaning roller 36 is pressed against the fixing member to clean the offset toner remaining on the surface of the fixing member except when the paper is passed.

According to the second aspect, the solenoid and the fixing device 21 are separated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 5 shows an overall schematic configuration of an internal mechanism of a laser printer which is an embodiment of the present invention.

Reference numeral 10 in the figure denotes the apparatus main body. A drum-shaped photosensitive member 11 that rotates clockwise in the drawing is provided in the center of the apparatus main body 10. Around the photoconductor 11, a charging device 12, an optical writing device 13, a developing device 14, a transfer device 15, and a cleaning device 16 are arranged in this order in the rotation direction. The electrical component section 17 is arranged above the optical writer 13.

On the other hand, on the right side of the apparatus main body 10 in the drawing, the paper feed cassettes 18 containing the sheets S are detachably attached in two upper and lower stages. A registration roller pair 19 is arranged on the right side of the transfer device 15. On the side opposite to the registration roller 19 with the transfer device 15 interposed therebetween, a transport device 20 is provided.
And the fixing device 21 are arranged side by side.

Therefore, in the illustrated laser printer, the sheet feeding rollers 22 and 22 are appropriately selected and driven to sequentially feed the sheets S from the sheet feeding cassette 18 to the registration roller 1.
Hit 9 and stop.

On the other hand, the surface of the photoconductor 11 is sequentially charged by the charger 12 while rotating clockwise in the figure, and the laser light is irradiated by the next optical writer 13 to electrostatically latent the surface. An image is formed, and subsequently, the electrostatic latent image is sequentially visualized when passing through the position of the developing device 14. Then, the registration roller 19 is driven in synchronization with the image to drive the sheet S to the photosensitive member 1.
Send it toward 1. Then, the visible image on the photoconductor 11 is transferred onto the surface of the sheet S by the transfer device 15. After the transfer, the surface of the photoconductor 11 is cleaned by the cleaning device 16, while the sheet S is sent to the fixing device 21 by the transport device 20,
The fixing device 21 fixes the transferred image on the sheet S. Then, the sheet discharge stack portion 26
Discharge to 26.

By the way, the above-mentioned fixing device 21 is provided with a fixing device case (not shown), and a fixing roller is provided between the opposing side plates.
A roller (fixing member) 30 and a pressure roller 31 (pressure member) are rotatably supported. Then, as shown in FIG.
The fixing roller 30 has a heater 32 built-in, and the pressure roller 31 is biased by a pressure spring (not shown) to fix the fixing roller 3.
Push to 0. A cleaning roller 36 is pressed against the fixing roller 30 by its own weight. The cleaning roller 36 rotatably mounts both ends of a roller shaft 36a on one end 35a of a swing lever 35 and supports the roller shaft 36a. The swing levers 35 have the support shafts 34 attached to the side plates 3
3, and the other end 35b of the swing lever 35 is engaged with one end 37a of the rotating arm 37. The other ends 37b of the rotary arms 37 are respectively provided with rotary shafts 38 of rotary solenoids (solenoids) 38.
Fix to a. Each rotary solenoid 38.3
The reference numeral 8 is provided outside the fixing device 21 at an appropriate position in the apparatus main body 10 and is electrically connected to the control means 42.

Therefore, as shown in FIG.
When the sensor 41 in front of the fixing device 21 detects the sheet S after the image transfer, the sensor 41 is turned on as shown in FIG. 3, and the detection signal is sent to the control means 42. Upon receiving the detection signal, the control means 42 sends an electric signal to the rotary solenoid 38. Then, Fig. 3
As shown in, the rotary solenoid 38 is turned on. Then, when the rotary solenoid 38 is driven, the rotating arm 37 is rotated by a predetermined angle in the clockwise direction indicated by the arrow in FIG.
The other end 35b is pushed down. Therefore, the swing lever 35 rotates counterclockwise around the support shaft 34 as indicated by an arrow to lift the cleaning roller 36. Then, as shown in FIG. 4, the cleaning roller 36 is separated from the fixing roller 30 when the paper is passed. At the time of passing the paper, the fixing roller 3
A part of the offset toner adhering to the surface of No. 0 adheres to the sheet S passing through the sheet, and the fixing roller 30 is self-cleaned.

Thereafter, the rear end of the sheet S is the sensor 41.
After passing through, the sensor 41 is turned off as shown in FIG. 3, and the rotary solenoid 38 is also turned off after a short time by the control means 42. Then, the cleaning roller 36 is lowered by its own weight, and the fixing roller 3 is again returned.
While pushing 0, at the same time, the other end 35b of the rocking lever 35 pushes up the rotating arm 37 to the state shown in FIG. After passing the sheet S, the fixing roller 30
The offset toner remaining on the surface of the sheet is cleaned by the cleaning roller 36. In this case, as can be seen from FIG. 3, when two or more sheets S are continuously fed, the fixing roll is set between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet.
The la 30 is cleaned with a cleaning roller 36. And
For example, at the time of maintenance, the front cover of the apparatus main body 10 is opened and the fixing device 21 is attached / detached in the length direction.

In the embodiment described above, the fixing roller is
The cleaning roller 36 is freely attached to and detached from the roller 30 by a rotary solenoid 38. However, although not shown in the drawings, the cleaning roller 36 may be freely attached to and detached from the fixing roller 30 by another driving means.

[0018]

Therefore, according to the first aspect of the present invention, the cleaning roller is separated from the fixing member during the passage of the paper, so that the toner saturation state of the cleaning roller is delayed to prolong the life thereof. The cleaning roller replacement cycle can be lengthened to reduce the running cost.

According to the second aspect, since the solenoid and the fixing device are separated from each other, the rotary solenoid can be prevented from malfunctioning due to heat because the solenoid is less affected by the heat generated in the fixing device.

[Brief description of drawings]

FIG. 1 is a perspective view of a peripheral portion of a fixing device of a laser printer which is an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an electrical connection state around the fixing device.

FIG. 3 is a time chart of the rotary solenoid and the sensor.

FIG. 4 is a state diagram of a fixing device in which a cleaning roller is separated from a fixing member during sheet passing by the rotary solenoid.

FIG. 5 is an overall schematic configuration diagram of an internal mechanism of the laser printer.

FIG. 6 is a schematic configuration diagram of a fixing device in a conventional laser printer.

[Explanation of symbols]

 21 fixing device 30 fixing roller (fixing member) 36 cleaning roller 38 rotary solenoid (solenoid) 42 control means

Claims (2)

[Claims] 1. A sheet after image transfer is placed in a fixing device, a transfer image on the sheet is fixed through a fixing member of the fixing device and a pressing member pressed against the fixing member, and a cleaning roller is attached to the fixing member. In an electrophotographic apparatus for cleaning the offset toner adhering to the fixing member by pressing the fixing roller, the cleaning roller can be brought into contact with and separated from the fixing member, and the cleaning roller is fixed at the time of passing a sheet. Comprising a control means for separating from the member,
Electrophotographic device. 2. The electrophotographic apparatus according to claim 1, wherein the cleaning roller is freely contacted and separated by a solenoid, and the solenoid is supported outside the fixing device.