JPH07295419A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device preventing the generation of such a trouble that transfer material is wound or polluted with an offset preventive oil without requiring a separate driving control means for a fixing roller by bringing an oil applying member into contact with the fixing roller, and bringing an oil removing member into contact with a pressure roller. CONSTITUTION:In the fixing device 23 feeding transfer material while clamping it with a fixing roller 23a on the fixed toner stuck side of the transfer material and a pressure roller 23b on the opposite face side, an oil applying member 23g is brought into contact with the fixing roller 23a, and an oil removing member 23j is brought into contact with the pressure roller 23b. With the oil removing member 23j thus brought into contact with the pressure roller 23b, even when the fixing roller 23a and the pressure roller 23b are rotated in the non-fed state of recording paper, the equivalent part of oil applied to the fixing roller 23a by the oil applying member 23g is shifted to the pressure roller 23b side and removed by the oil removing member 23j.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus for forming a toner image and transferring and fixing the toner image onto a transfer material such as plain paper or a transparent sheet for an overhead projector. The present invention relates to a fixing device in which a transfer material is nipped and sent by a fixing roller on the surface to which the toner to be fixed is attached and a pressure roller on the opposite surface.

[0002]

2. Description of the Related Art In a fixing device as described above, an oil applying member is brought into contact with a fixing roller to apply offset preventing oil in order to prevent the toner from being offset. The applied oil is sequentially carried away by the transfer material when the transfer material is being passed, but when the transfer material is not being passed, the oil is excessively applied and moves to the pressure roller side. Then, the offset preventing oil contaminates the next transfer material. In order to prevent the occurrence of this problem, an image forming apparatus is known in which the fixing roller is rotated only when the transfer material is passed through. However, in this case, a transfer material detection sensor is provided immediately before the fixing roller. However, there is a problem in that the drive control means for rotating and stopping the fixing roller is separately required based on the information, resulting in an increase in cost.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and the toner can be rotated and stopped without the need for a separate drive control means for the fixing roller. Even when the transfer roller and transfer belt are rotated and stopped while being pressed against the image forming body or the toner image forming body during transfer, the transfer material is squeezed between the transfer material and the toner image forming body. An object of the present invention is to provide a fixing device that does not cause problems such as contamination or winding of the transfer material.

[0004]

SUMMARY OF THE INVENTION The present invention is a fixing device in which a transfer material is sandwiched between a fixing roller on the surface of the transfer material to which the toner to be fixed is attached and a pressure roller on the opposite surface, and the transfer material is fed to the fixing roller. A fixing device is characterized in that an oil applying member is brought into contact with the pressure roller and an oil removing member is brought into contact with the pressure roller. This configuration achieves the above object.

[0005]

That is, in the fixing device of the present invention, since the oil removing member is in contact with the pressure roller, excess oil is fixed even if the driving of the fixing roller is interlocked with the driving of the toner image forming body. It is possible to prevent the transfer material from being contaminated or wrapped around the roller or the pressure roller.

[0006]

The present invention will be described below with reference to the illustrated examples.

FIG. 1 is a schematic side view of the configuration of an image forming apparatus in which the fixing device of the present invention is used. FIG. 2 is a schematic side view of the configuration of the fixing device of the present invention.

The operation of the image forming apparatus shown in FIG. 1 will be briefly described. A photosensitive drum 10 as a toner image forming body coated with an OPC photosensitive layer on its surface is driven and rotated in a clockwise direction indicated by an arrow, and a static eliminator 11 is used. After the charge is removed to remove the charge at the time of the previous toner formation, the peripheral surface is uniformly charged by the charger 12 to prepare for the formation of a new toner image. The image exposure means 13 makes image exposure based on an image signal incident on the uniformly charged surface. The image exposure unit 13 swings and scans a laser beam emitted from a laser light source described later by the rotating polygon mirror 131, and the fθ lens 132, a reflection mirror 133, and the like on the peripheral surface of the photoconductor drum 10 that has been charged in advance. To form an electrostatic latent image on the surface of the photosensitive drum 10.

Around the photosensitive drum 10, yellow (Y), magenta (M), cyan (C), and black (K), respectively.
Is provided with developing devices 14A to 14D filled with a developer composed of a mixture of a toner and a magnetic carrier, and the first color development for the first electrostatic latent image includes a magnet and is a developer. Developing sleeve 141 that rotates while holding
Done by The developer is regulated to a predetermined thickness on the developing sleeve 141 by the layer forming rod and is conveyed to the developing area. An AC bias voltage VAC and a DC bias voltage VDC are superimposed and applied between the photoconductor drum 10 and the developing sleeve 141. Here, the potential of the exposed portion of the photosensitive drum 10 is VL, the surface potential of the charged photosensitive layer other than the exposed portion is VH, and the DC bias voltage VDC is | VH |> |
By setting so that VDC |> | VL | is established, the toner that is given the opportunity to be separated from the carrier by the AC bias voltage VAC has a higher potential than VDC.
It does not adhere to the H portion, but adheres to the exposed portion of potential VL lower than VDC, and the electrostatic latent image is visualized and developed.

After the development of the first color is completed in this way, the image forming process of the second color (for example, magenta) starts.
The photosensitive drum 10 is uniformly charged again, and a latent image based on the image data of the second color is formed by the image exposure means 13 and developed by the developing device of the second color. Third color (cyan), 4
For the color (black), the image forming process is performed as in the case of the second color, and development of a total of four colors is performed on the photosensitive drum 10.

On the other hand, the recording paper P of the transfer material fed from the paper feeding cassette 21 by the paper feeding mechanism 22 is transferred between the photosensitive drum 10 and the transfer belt 31 by the transfer belt device 30 in which the transfer belt 31 is stretched. The multicolor image on the peripheral surface of the photosensitive drum 10 is collectively transferred to the recording paper P by being fed to the nip portion (transfer area) 35 formed on the recording paper P. Here, a high voltage is applied to the shaft 32a of the upstream side holding roller 32 of the transfer belt 31, and the conductive brush 34 installed at a position facing the shaft 32a with the transfer belt 31 interposed therebetween is grounded. The fed recording paper P enters between the brush 34 and the transfer belt 31 and enters the transfer area while being attracted to the transfer belt 31 by the charges injected into the recording paper P via the brush 34. . Photoconductor drum
The recording paper P separated from 10 is separated from the transfer belt 31 while being neutralized by using the shaft 33b of the holding roller 33 on the downstream side which stretches the transfer belt 31 as a counter electrode. The transfer belt 31
The cleaning blade 37 removes the toner attached to the. Further, the transfer belt 31 is separated from the photoconductor drum 10 around the shaft 33b of the holding roller 33 on the downstream side as a rotation center during the formation of the multicolor image.

Recording paper P separated from the transfer belt device 30
Is conveyed to a fixing device 23 composed of a pair of fixing rollers and a pressure roller, and pressure or further heat is applied between the pair of rollers to melt and fix the attached toner image. After that, it is carried out of the device.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is discharged to the cleaning device 16 after being discharged by the static eliminator 15, and is cleaned by the cleaning blade 16a which is in contact with the photosensitive drum 10. It is scraped off inside, carried out by a screw, etc., and stored in the collection box. The photoconductor drum 10 from which the residual toner has been removed by the cleaning device 16 is neutralized by the static eliminator 11,
It is uniformly charged by the charger 12 and is ready for the next image forming cycle.

When the recording paper P is wound around the photosensitive drum 10 without being separated from the transfer belt 31 to the fixing device 23 side and enters above the static eliminator 15, the cleaning blade is used.
A jam sensor 36 for detecting the winding of the recording paper P is installed near the static eliminator 15 in order to prevent the damage of the 16a and the electrode wire.

In the fixing device 23 of FIG. 2, the fixing roller 23a and the pressure roller 23b, which are in pressure contact with each other by pressure means (not shown), rotate and stop in conjunction with the rotation and stop of the transfer belt 31, so that separate drive control is performed. If no means is required, but the image forming apparatus forms a monocolor image, a fixing roller
It is also possible that 23a or the like rotates and stops in conjunction with the photosensitive drum. Further, the fixing roller 23a and the pressure roller 23 in the illustrated example
Although b has a built-in heater 23c in order to rise to the fixing temperature and to speed up the fixing speed, even if only one is built in, the heater 23c is built in by being heated from the outside by an infrared lamp or the like. The heater 23c may not be provided, or the heater 23c may not be built in by heating the recording paper P or the toner image before reaching between the rollers with an infrared lamp or the like.

In any case, the fixing roller 23a and the pressure roller 23b are directly or indirectly heated to fix the toner image on the recording paper P, and the fixing roller 23a presses the toner image on the recording paper P. Since the toner is fixed by fixing it, stains such as toner and paper powder easily adhere to it, and the pressure roller 23b
Stains are also transferred from the fixing roller 23a or directly onto the recording paper P.
Since the paper powder is easily transferred from the surface layer 23d, both the fixing roller 23a and the pressure roller 23b are made of a fluororesin layer or a silicone resin layer which is excellent in heat resistance and oil resistance against the offset preventing oil and is hard to attach dirt. Further, the fixing roller 23a has an elastic layer 23e made of silicon rubber or the like which is also excellent in heat resistance and oil resistance under the surface layer 23d so as not to crush the toner image excessively. Is preferred.

Around the fixing roller 23a as described above,
A separating claw 23f for preventing the recording paper P on which the toner image is fixed from winding, and a silicone resin or a fluororesin containing an oil for applying an offset prevention oil such as silicone oil on the surface of the fixing roller 23a on the downstream side. An oil application member 23g made of resin sponge, a temperature sensor 23h for detecting the surface temperature of the fixing roller 23a, and an elastic surface layer such as silicon rubber for smoothing the oil on the surface of the fixing roller 23a which comes into contact with the recording paper P are provided. The leveling roller 23i which it has is arrange | positioned. By thus uniformly applying the offset prevention oil to the fixing roller 23a, it is possible not only to fix the monochrome toner image but also to fix the color toner image requiring a relatively high temperature. Also, it is possible to prevent the toner from adhering to the fixing roller 23a.

Further, around the pressure roller 23b, a separation claw 23f for preventing the recording paper P on which the toner image is fixed from winding.
And removes the offset prevention oil adhering to the surface of the pressure roller 23b on the downstream side thereof, and comes into contact with the absorber such as felt, sponge, filter paper laminate or the suction nozzle and the surface of the pressure roller stretched at its inlet. When the oil removing member 23j, which is a suction means composed of a rough cloth such as a screen shear, and the oil removing member 23j is the absorber described above, the solids attached to the surface of the pressure roller 23b are further attached to the downstream side thereof. A capturing member 23k called a suction means including a brush or a suction nozzle to be removed and a scraper blade provided on a downstream side wall of the nozzle in the rotation direction of the pressure roller.
And a temperature sensor 23h for detecting the surface temperature of the pressure roller 23b are arranged on the most downstream side.

For the oil removing member 23j, in particular, a felt of aromatic polyamide fiber (for example, Nomex felt manufactured by DuPont, USA) is preferably used because of its low cost and excellent durability and effect. By contacting the pressure roller 23b with a pressure per unit width of 3 gf / mm or more, the oil on the pressure roller 23b can be effectively removed. Further, the capture member 23k is also low in cost and excellent in durability and effect. Therefore, the capture member 23k has aromatic polyamide, polyimide, or polyphenylene sulfide (PP).
A brush having a brush made of a heat resistant resin such as S) is preferably used. When such a brush is brought into contact with the pressure roller 23b at a pressure per unit width of 2 gf / mm or more, the solids adhering to the pressure roller 23b can be effectively removed.

As described above, by contacting the oil removing member 23j with the pressure roller 23b, even if the fixing roller 23a and the pressure roller 23b are rotated without feeding the recording paper P. The portion of the oil applied to the fixing roller 23a by the oil applying member 23g is equivalent to the pressure roller 23.
Since it moves to the b side and is removed by the oil removing member 23j,
The recording paper P fed in next is prevented from being contaminated by excess oil or being wound around the fixing roller 23a or the pressure roller 23b. Further, since the capture member 23k is in contact with the pressure roller 23b, the toner, the paper dust, etc. transferred from the fixing roller 23a and the pressure roller directly from the recording paper P when the recording paper P is not fed.
Since the solids such as paper dust transferred to 23b are removed by the capturing member 23k, not only the pressure roller 23b but also the fixing roller 23a can be kept clean.

Specific examples of the present invention will be shown below.

A fixing device 23 as shown in FIG. 2 is used in the color image forming apparatus as shown in FIG.
23a comprises a 1 mm thick fluororesin surface layer, a 3 mm thick silicon rubber elastic layer thereunder, a 2 mm thick aluminum roller core thereunder, and a heater inside the roller nucleus, and the pressure roller 23b has a 2 mm thick fluorine core. The pressure roller 23b is rotated in conjunction with the rotation of the transfer belt 31, and the fixing roller 23a is driven to rotate, with a resin surface layer, a 2 mm thick aluminum roller core thereunder, and a heater inside the roller core.

The oil applying member 23g on the fixing roller 23a side is made of polymerized polyurethane sponge and Nomex felt, the leveling roller 23i is made of a silicone rubber surface layer, and the pressure roller 23b is used.
The oil removing member 23j on the side has a thickness of 3 mm and a basis weight of 570 g / m ²
Nomex felt was used to abut against the pressure roller 23b at a pressure per unit width of 5 gf / mm, and a brush having a brush with a length of 3 mm of PPS fiber was used as the capture member 23k at 3.3 gf for the pressure roller 23b. The pressure was applied per unit width of / mm.

Although a color image was recorded on 50,000 sheets of recording paper P by the above-mentioned color image forming apparatus, no contamination or winding of the recording paper P due to offset preventing oil was observed, and the fixing roller 23a and the pressure roller 23b were clean. Kept in.

[0025]

The fixing device of the present invention does not require a separate drive control means for the fixing roller, and can prevent the transfer material from being contaminated or wrapped around by the offset preventing oil. Is obtained.

The present invention is not limited to the fixing roller and the pressure roller having a built-in heater, and the leveling roller and the capturing member.

[Brief description of drawings]

FIG. 1 is a schematic structural side view showing an example of an image forming apparatus in which a fixing device of the present invention is used.

FIG. 2 is a schematic side view of a configuration showing an example of a fixing device of the present invention.

[Explanation of symbols]

 10 Photosensitive drum 23 Fixing device 23a Fixing roller 23b Pressure roller 23c Heater 23d Surface layer 23e Elastic layer 23f Separation claw 23g Oil applying member 23h Temperature sensor 23i Leveling roller 23j Oil removing member 23k Capture member

Claims (3)

[Claims] 1. A fixing device in which a transfer material is sandwiched between a fixing roller on the surface of the transfer material on which the toner to be fixed is attached and a pressure roller on the opposite surface of the transfer material, and an oil applying member is brought into contact with the fixing roller, A fixing device characterized in that an oil removing member is brought into contact with a pressure roller. 2. The fixing device according to claim 1, wherein a capturing member for removing solids adhering to the pressure roller is brought into contact with a downstream side of the oil removing member of the pressure roller. 3. The oil removing member, wherein the fixing roller has a fluororesin layer on a surface thereof and a silicone rubber layer thereunder, and the pressure roller has a heater therein and a fluororesin layer on a surface thereof. The fixing device according to claim 2, wherein a felt is used for the sheet, and a brush is used for the capturing member.