JPH0421885A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing roller with a potential having a little offset by using a conductive ethylene tetrafluoride resin (PFA) tube on the surface layer of the fixing roller and providing a conductive adhesive layer between this PFA tube and a metallic pipe. CONSTITUTION:On the surface of the metallic cylindrical pipe 2 of the fixing roller 1, the conductive layer 3 which is the conductive adhesive layer is formed, and the conductive PFA tube 4 covers this conductive layer 3. The conductive PFA resin is melted until it is melted a little and it is fixed to the conductive layer 3. And the metallic pipe 2 is grounded through a rectifying element 16, and its rectifying direction is a direction in which the charge of a reverse polarity to the electrifying polarity of a developer is made to escape. Consequently, the charge electrified by a friction between the PFA tube 4 and a transferring material can be comparatively and easily escaped through the conductive layer 3 and the metallic pipe 4. It is good to form the layer 3 so that thickness of the layer 3 is between 10-100mum and surface roughness is 2s-15s. Thus, the offset is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fixing device having a fixing roller that performs heat fixing.

[Prior Art] Conventionally, as a heat roller used in a heat fixing device, the heat rollers shown in FIGS.
A fixing roller like the one shown in the figure is used.

Figure 4 shows a tube 4 made of PFA resin (tetrafluoroethylene resin, perfluoroalkogine ethylene resin copolymer) coated on the -L of a metal pipe 2 made of aluminum or stainless steel, and then heated and shrunk. A PFA tube is tightly attached to the surface of a metal pipe 2 by heating or melting it. The characteristics of this method are that the manufacturing method is simple and can be manufactured at low cost, and that the coating is uniform and sufficient strength is obtained by using a tube.

Further, an adhesive layer 3 is placed on the metal pipe 2 as shown in FIG.
It has also been proposed that after coating the material, PTFE resin 20 (tetrafluoroethylene resin) is baked. This method is
Since it is a powder coating, there are fine holes on the surface, the strength of the coating is somewhat poor, and the surface charge tends to escape toward the metal substrate, making it difficult to be charged.

[Invention or problem to be solved] However, according to No. 41M, the surface is constant; by being repeatedly heated by the metal vibrator 2 or the heater of the heat fixing device i), the surface There was a problem with it oxidizing. When the surface becomes oxidized in this way, the oxidized layer becomes an insulator and impedes the movement of charges. In particular, aluminum and minilum are easily oxidized, and an oxidized layer is easily formed on their surfaces.

It also improves the adhesive strength between the IIFA tube and the metal vibrator]
In order to do this, a method of oxidizing the surface of the metal barb is also used, and for the reasons mentioned above, it is difficult for the surface charge to escape. Therefore, τ, PFA resin Q1. - Friction between paper and paper (generated by 12 volts) The problem was that the charges accumulated on the surface of the roller were difficult to reduce and static offset was likely to occur.

In addition, the roller made of rF resin (not shown in FIG. 5) has the problem that the charge on the roller surface tends to escape easily, or that there is a large amount of offset when reverse development is performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device equipped with a single roller that can solve the above problems and prevent the occurrence of offsets and stains.

[Means for Solving the Problems] According to the present invention, the following object is to provide a fixing device having a fixing roller having a conductive PFA tube covered on a metal cylinder; ] - The thickness between the PFA tubes is 10 micrometers.
1~6100 micrometers, surface roughness 2S
A conductive adhesive layer is formed for 15 seconds from 1 to 1.
This is achieved by: The metal cylindrical body is grounded through a rectifying element, and the rectifying direction is oriented so that charges having a polarity opposite to that of the developer are not released.

[Function] Since the fixing roller of the present invention has a conductive adhesive layer formed between the metal cylinder and the PF8, the surface of the metal cylinder is prevented from being oxidized even when heat fixing is repeated. I
) The electric charge due to frictional 912 electricity generated in the FA tube is not properly released to the metal cylindrical body.

Roughly speaking, the metal cylindrical body -1- is grounded through the rectifying teeth 1'-, so that only charges having a polarity opposite to that of the developer are allowed to escape. Therefore, the fixing roller is charged to the same polarity as the above-mentioned charging polarity, and an electrostatic repulsive force is generated between the fixing roller and the developer, thereby preventing offset.

In addition, if the thickness of the adhesive layer is set to 10 gm or less, there will be no uneven coating, and it will exhibit excellent adhesion, and 1 fltl.
It has been found that the thermal resistance does not increase beyond pLi and does not affect the fixing performance.

Furthermore, the surface roughness of the adhesive layer is 2S or higher, so it has a PF of 8 without slipping, and it has a surface roughness of 158 or lower.
It turns out that there is no effect of unevenness on the F8 tube surface [)
Ta.

"Embodiment" A first embodiment and a second embodiment of the present invention will be described using FIGS. 1 and 3.

<First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows an embodiment of a fixing roller 1 of the present invention.

In FIG. 1, 2 is a metal cylindrical pipe made of metal such as aluminum or stainless steel, and a conductive layer 3, which is a conductive adhesive layer, is formed on the surface of the vibrator 2. This conductive layer 3 is made of Teflon (registered trademark) 856-204 or 850- manufactured by DuPont, for example:
114 to which fine powder of aluminum, copper, carbon, or the like is added as a substance that imparts conductivity. This layer was coated with a thickness of Xθ ~ 30 pm, and then
Baked at a temperature of around 50°C. A conductive PFA tube 4 having a thickness of 20 to 70 μm is placed on the conductive layer 3, and the conductive PFA tube is melted until the resin melts.
)-Indication "I! is fixed to the IC layer 3.

By providing a conductive adhesive layer between the metal pipe 2 and the PF 8-F 4 in this way, 1) the charges generated due to the friction between the 1-A tune and the transfer material can escape relatively easily; Become. The resistance of this conductive layer 3 is desirably 1()9Ω or less, and its thickness is preferably formed between 10 and IO[1go+.

In this embodiment, the conductive layer 3 may be made of the above-mentioned materials, or other materials may be used as long as they have ti11@ characteristics, conductive particles are easily dispersed, and have good adhesive properties. For example, Toshiba Silicone's polysiloxane oil-resistant Brimer XE
9214 with the above-mentioned conductive particles dispersed in it.
C is also good.

Providing a conductive layer and dispersing metal particles as described above has the advantage of improving thermal conductivity and improving fixing performance.

As mentioned above, the resistance of the conductive layer must be IO%'Ω or more. This is because if the resistance is high, it is difficult for charges to escape, and the surface potential does not attenuate during one rotation of the roller. The capacitance per unit length of this fixing roller is about 1000 pF"C, so in order to attenuate the charge within 1 second, it is less than 109Ω, preferably 108Ω.
Ω or less is required. Note that the electrical resistance of the roller is 1 c in width.
A metal foil of m was wound around a roller, and the resistance between it and the core metal was measured.

If the thickness of this conductive layer is less than 10 μm, uneven coating may occur and the adhesion between the conductive PFA tubes and the core metal will be weak, and if it is more than 100 μm, thermal resistance will increase and there may be problems with fixing properties. arise.

Further, the surface roughness of this conductive layer must be between 2S and 15S due to the relationship between the adhesiveness of the conductive PFA tubes on one surface and the offset. If it is smoother than 2S, PF
If the A-tube slips and is rougher than 15 seconds, the surface of the PFA tube will be affected by the unevenness of the conductive layer. Therefore, the surface roughness of the conductive layer must be within the above range of values. Here, "S" is the measured average surface roughness in gm.

Next, a fixing device using the fixing roller of this embodiment will be described with reference to FIG.

As described above, the fixing roller l has a conductive adhesive layer 3 and a conductive PF tube layer 4 formed on the metal pipe 2, and has a halogen lamp 5 inside. This halogen lamp 5 is controlled by the output of a thermistor 6 so that its temperature is kept constant.

A pressure roller 7 is made up of a core metal 8 and a silicone rubber layer 9. The transfer material 1 (1 is guided by the kite I+ and enters the nip portion, and is separated from the fixing roller l by the separating claw 12. The transfer material 1 (1) is coated with silicone oil or removes the toner offset from the fixing roller. 14 is a conductive flange for leaking the surface charge of the pressure roller 7.

In the apparatus of this embodiment, negatively charged OPC (organic semiconductor) is used and reversal development is performed, so the toner 15 has negative polarity. Therefore, in this embodiment, if the fixing roller l is negatively charged, the offset will be reduced and the charge of the toner will be difficult to escape. As a method for charging the fixing roller l to a more negative polarity, a diode 16 serving as a rectifying element is connected to the metal vibrator 2 of the fixing roller l in the direction shown in FIG. 2, and one end is grounded. In this way, negative charges are blocked by the diode 16 and do not escape, while positive charges leak through the tie-out 16. When all layers of the fixing roller l are made conductive, the potential of the fixing roller becomes approximately Ov.
, and the offset becomes worse, so it is necessary to use the tie auto 16 to set the potential of the fixing roller l to a negative potential.

Conventionally, the surface potential of the fixing roller reaches up to several hundred volts after paper passes, but with the fixing roller of this embodiment, it can be made to about -200 to 3 II OV, and the toner offset to the fixing roller 1 We were able to reduce the amount.

It should be noted that the toner offset is caused not only by the fixing roller but also by the charging of the pressure roller, or in the example shown in FIG. 2, the charge is removed from the surface by the charge removing flange 14. By using this static elimination flage, the surface potential of the pressure roller was able to be reduced from -2 to about 3 kV or -lkV.

In this way, by polarizing the surface potentials of the fixing roller and pressure roller so that they do not offset or reducing them, toner offset has been reduced, improving the durability of the cleaning felt and greatly reducing the occurrence of scratches on the fixing roller. We were able to extend the durability by twice as much as before.

<Second Embodiment> Next, a second embodiment of the present invention will be described using FIG. 3. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment differs from the first embodiment in that the silicone rubber layer 9 of the pressure roller is made to have electrical conductivity.

According to this embodiment, the static elimination flange 14 in the first embodiment is
can be removed. In this case, the core bar 8 needs to be grounded.

In this embodiment, as shown in FIG. 3, two tie autos connected to the fixing roller l are used in a stacked manner to enhance the rectifying effect of the tie auto. Further, a diode 17 is also connected to the pressure roller 7, so that the potential of the pressure roller 7 is brought to a more positive polarity side.

With this configuration, the charge on the pressure roller can be reduced without reducing the static elimination effect due to the accumulation of dust on the static elimination flage.

In the embodiments described above, the surface of an aluminum or stainless steel vibrator was polished to form a conductive adhesive layer on the core metal of the fixing roller, or the weighting accuracy of the metal vibrator was increased by -1-. It is also possible to maintain the C and use the drawn material as it is.

In this way, it becomes possible to manufacture the fixing roller at a lower cost.

Further, in the embodiments described above, the felt member 13 was used to clean the roller surface, but it is not necessarily necessary in cases where Offcera is 1 or less.

[Effects of the Invention] As described above, by using conductive 1) FA tube on the surface layer of the fixing roller and providing a conductive adhesive layer between it and the metal vibrator, a strong coating of PF 8 tube can be obtained. At the same time, by adding an element to the fixing roller that allows a charge to flow in one direction, it has been possible to set the fixing roller to a potential that reduces offset.

The combination of these reduces the offset during fusing,
Cleaning parts have become possible to the point where they are no longer necessary.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic structure of a fixing roller according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view showing a schematic structure of a fixing device using the fixing roller of FIG. 1, and FIG. 4 is a cross-sectional view showing the schematic structure of a device according to a second embodiment of the invention; FIG.
A, 5th]'A is PTFF. 1 is a cross-sectional view showing a schematic configuration of a conventional fixing roller using resin. l... Fixing roller 2... Metal cylindrical body (metal roller) 3...
...Conductive adhesive layer (conductive layer) 4...PF 8 tube

Claims (1)

[Claims] In a fixing device having a fixing roller in which a conductive PFA tube is coated on a metal cylinder, the thickness between the metal cylinder and the PFA tube is between 10 micrometers and 100 micrometers. , surface roughness from 2S to 1
A 5S conductive adhesive layer is formed, and the metal cylindrical body is grounded through a rectifying element, and the rectifying direction is a direction that releases charges having a polarity opposite to the charged polarity of the developer. Fixing device.