JP2003241552A - Fixing device, fixing method, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which prevents scratch on the surface layer of a fixing belt, worsening of scratch, and leak even when applying a voltage to a fixing belt, and to provide a fixing method using the fixing device and an image forming apparatus having the fixing device. <P>SOLUTION: The fixing belt 12C has a substrate having a resistance value of 1×10<SP>0</SP>to 1×10<SP>6</SP>Ω and the surface layer having a resistance value of 1×10<SP>9</SP>to 1×10<SP>14</SP>Ω which is disposed on the periphery of the substrate and is in contact with a voltage applying means 40. A resistance applying means having a resistance value of 1×10<SP>9</SP>to 1×10<SP>14</SP>Ω which applies a resistance between the substrate and a ground is provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless fixing belt, a pressure roller such as a pressure roller that contacts the peripheral surface of the fixing belt, and a pressure member that contacts the peripheral surface of the fixing belt. The present invention relates to a fixing device having a voltage applying unit for applying a voltage to a fixing belt, a fixing method using the fixing device, and an image forming apparatus having the fixing device.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine such as a digital copying machine, a facsimile such as a plain paper facsimile, a printer such as a laser beam printer and the like, which is sometimes referred to as an OA equipment, generally has an image forming process mechanism such as an electrophotographic system. Thus, an unfixed toner image is formed and carried on a sheet of recording medium, which is a transfer method or a direct method.

Since the toner of the unfixed toner image is easily peeled off, heat or pressure or both heat and pressure is applied to the toner to melt and deform the toner, and then the toner is cooled and solidified to be permanently applied to the surface of the paper. It is necessary to fix them physically. This process is called the fixing process,
This is performed by the fixing device provided in the image forming apparatus.

As a fixing device, a fixing roller, which is also called a heating roller heated by a heater as a heating means, and a nip portion which is in contact with the fixing roller and is a contact area with the fixing roller, rotates in the same direction as the fixing roller. A pair of heat rollers, in which a pressure roller or the like is used as a constituent element, and a sheet on which toner is fixed is conveyed and passed through the nip portion by rotation of both rollers to heat and press to fix the toner image. The device is known.

As the fixing device, a rotating endless fixing belt for conveying a sheet-shaped recording medium on which toner is fixed by being heated by a heater as a heating means,
A heating roller around which the fixing belt is wound, a fixing roller, and a pressure roller as a pressure member that is arranged to face the fixing roller via the fixing belt. There is known a so-called belt fixing device of a type in which a sheet on which toner is fixed is conveyed and passed by the rotation thereof to a nip portion 16 which is an abutting area to be heated and pressed to fix a toner image. There is.

By the way, the toner forming the toner image fixed on the sheet is electrostatically adsorbed to the image carrier such as the photoconductor provided in the above-mentioned image forming process mechanism. Is charged during development, and is charged even after being transferred from the image carrier onto the paper.

In each of the heat roller pair type fixing device and the belt fixing device, the fixing roller and the fixing belt are located on the side of the recording medium carrying the toner image. When the fixing belt is charged with a polarity opposite to that of the toner forming the toner image, the toner is offset to the fixing roller and the fixing belt to cause toner scattering, which causes image disturbance.

Further, when the toner is offset on the fixing roller and the fixing belt, there is also a problem that the offset toner contaminates a sheet to be fixed next. Further, when peeling discharge occurs when the paper is peeled from the fixing roller and the fixing belt, the paper to be fixed next is affected and the image is disturbed. In order to solve such a problem, according to Japanese Patent Laid-Open No. 2001-209260, etc.,
A technique has been proposed in which a voltage having the same polarity as that of toner is applied to a fixing roller and a fixing belt.

[0009]

However, in the belt fixing device, particularly when the belt fixing device is mounted in the image forming apparatus capable of forming a color image, the surface layer of the fixing belt is
It is often made of silicone rubber, but silicone rubber is a very fragile material, and when a voltage is applied,
There is a problem that scratches are likely to occur, the generated scratches are easily spread, and further, electrical noise is generated due to leakage.

Particularly, when a voltage is applied to the surface layer of the fixing belt and the back side of the fixing belt is directly grounded, even if the surface layer of the fixing belt is scratched, which is not a problem normally. , This scratch causes leakage, and current flows in to spread the scratch, and the spread of the scratch causes a discharge phenomenon to generate electrical noise, and further spreads the scratch on the fixed image. There is a problem that it will be affected.

An object of the present invention is to prevent a surface of the fixing belt from being scratched, spread, or leak even when a voltage is applied to the fixing belt, and a fixing device using the same. A method and an image forming apparatus having the fixing device.

[0012]

The invention according to claim 1 is
A rotating endless fixing belt, a pressure member that contacts the peripheral surface of the fixing belt and rotates in the same direction as the identification fixing belt in the contact area of the fixing belt, and a pressing member that contacts the peripheral surface of the fixing belt. A fixing device having a voltage applying unit for applying a voltage to a fixing belt, wherein a recording medium carrying a toner image is passed through the contact area to fix the toner image on the recording medium. Is 1 × 10 ⁰ to 1 × 1
0 and ⁶ Omega substrate, outer peripheral is disposed in the voltage applying means of the base abuts, the resistance value of ¹ × 10 9 ~1 × 10 ¹⁴
And a resistance imparting means having a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω for imparting resistance between the substrate and the ground.

According to a second aspect of the present invention, in the fixing device according to the first aspect, the first belt around which the fixing belt is wound is wound.
The first roller has a grounded metal cored bar and a resistance value of 1 × arranged on the outer periphery of the cored bar.
And a resistance layer having a resistance of 10 ⁹ to 1 × 10 ¹⁴ Ω, and the resistance applying unit includes the resistance layer.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the fixing device described above, the fixing roller includes a second roller around which the fixing belt is wound, and a grounded first bearing member that forms a bearing of the second roller, and the second roller is made of metal. And the resistance value of the first bearing member is 1 × 10 ⁹ to
It is 1 × 10 ¹⁴ Ω, and the resistance applying means has a first bearing member.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the fixing device described above, a third roller wound around the fixing belt for heating the identification fixing belt,
A second bearing member that forms a bearing for the third roller, the third roller is made of metal, and the second bearing member has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω. The resistance imparting means has a second bearing member.

The invention according to claim 5 is the invention according to claims 1 to 4.
In any one of the fixing methods, the fixing device is used for fixing.

The invention according to claim 6 is the invention according to claims 1 to 4.
An image forming apparatus having the fixing device described in any one of

[0018]

FIG. 1 is a schematic diagram of a fixing device and an image forming apparatus having the same according to an embodiment of the present invention. The image forming apparatus shown in FIG. Shows. The image forming apparatus is not limited to a copying machine, but may be a printer or a facsimile machine. The image forming apparatus 1 forms a monochromatic image, but may be one capable of forming a color image.

The image forming apparatus 1 does not discharge a recording sheet, which is a sheet-like recording medium, to the outside of the casing 1A, but can discharge the image inside the casing 1A. It is a forming device. The image forming apparatus 1 is provided with a paper discharge tray 2 that is a paper discharge unit at a substantially central portion in the height direction of the housing 1A.
A document reading section 3 is provided on the upper side of the sheet discharge tray 2 as a boundary.
However, an image forming unit 4 described later is provided in the lower part.

In the case of this embodiment, the image forming section 4 is provided with a photosensitive drum 5 as an image carrier corresponding to a drum-shaped latent image carrier, and the photosensitive drum 5 is driven by a drive source (not shown). In the figure, it rotates counterclockwise. Around the photosensitive drum 5, a charging device 6, a writing device 7, a developing device 8, a transfer device 9 and a cleaning device 10 for executing an electrophotographic copying process are arranged along the rotation direction.

Below the photoconductor drum 5, there is arranged a paper feeding device 11 for stacking paper sheets and supplying the stacked paper sheets to the image forming section 4, and also for feeding the paper sheets indicated by the two-dot chain line arrow. A fixing device 12 and a paper ejection device 13 as a paper ejection unit are arranged on the downstream side of the transfer device 9 and the upstream side of the paper ejection tray 2 in the feeding direction.

The document reading section 3 is equipped with a light source 3A for scanning a document placed on the document table and a reflecting mirror 3B for optical path conversion, and the reflected light from the document is read through the reading optical system 3C. Is incident on the optical element 3D such as a CCD, and is output to the control unit 14 as image information of the document by the optical element 3D.

Although not shown, the writing device 7 includes a semiconductor laser that emits light in accordance with image information of a document input to the control unit 14, a reflecting mirror and an image forming lens that form an image forming optical system. The scanning light from the polygon mirror 7A is applied to the photosensitive drum 5 to form an electrostatic latent image.

The paper feeding device 11 is provided with a paper feeding tray feeding roller and a registration roller having a well-known structure. As the paper feeding device, another openable paper feeding tray is provided on a part of the wall portion of the image forming apparatus 1 as shown by the chain double-dashed line in the figure, and the paper feeding to the image forming portion 4 is performed by either one. It is supposed to be.

The semiconductor laser is designed to emit light on the basis of an image signal from the control section 14. In the control section 14, not only the image information from the document reading section 3 but also a printer is used. The semiconductor laser drive is controlled by an image signal corresponding to a print signal and a transmission signal when used as a facsimile machine. Here, the control unit 14 allows the image forming apparatus 1 to have a character as a digital multi-function peripheral having functions as a printer and a facsimile apparatus as well as a copying machine.

As shown in FIG. 2, the fixing device 12 includes a fixing roller 12A as a first roller capable of interlocking rotation by contacting each other so that the paper P can be nipped and conveyed so as to face each other, and a fixing roller. 12A, a pressure roller 12B as a pressure member, and a heating belt 12 as a rotating endless fixing belt as a sheet conveying member.
C and a heating roller 12D as a third roller for heating the heating belt 12C, which is formed by stretching the heating belt 12C between the fixing roller 12A and the fixing roller 12A.

The fixing device 12 also applies a portion of the spreading surface of the heating belt 12C from the inside in order to widen the width of the nip portion 16 which is the contact area between the heating belt 12C and the pressure roller 12B, that is, the nip width. The tension roller 12E, which is a second roller as an auxiliary roller for contacting the heating belt 12C and winding the heating belt 12C around the pressure roller 12B, the leveling roller 21 as an oil supply roller, and the abutting contact with the leveling roller 21, , And an application roller 22 as an oil application roller that is abutted against the heating belt 12C.

The fixing device 12 is also in contact with the fixing roller 12A via the heating belt 12C at a position upstream of the application roller 22 in the rotating direction of the heating belt 12C so as to be driven and rotated by the fixing roller 12A. By applying a voltage to 12C, the heating belt 1
It has a bias roller 40 as a voltage applying means for applying a bias by 2C.

The fixing device 12 is also downstream of the contact position between the leveling roller 21 and the coating roller 22 in the rotation direction of the leveling roller 21, and includes the leveling roller 21 and an oil discharge portion 20D which will be described later. A felt member 23 made of felt is provided as a contact member that is a cleaning member that contacts the leveling roller 21 at a position upstream of the contact position.

The position of the tension roller 12E which comes into contact with the expanding surface of the heating belt 12C is set to a position facing the peripheral surface of the pressure roller 12B, and the contact range of the expanding surface of the heating belt 12C is set to that of the pressing roller 12B. The heating range for the sheet P can be widened from a part of the peripheral surface to the position where the fixing roller 12A and the pressure roller 12B face each other. In this way, the heating belt 12 is wound around the fixing roller 12A, the tension roller 12E, and the heating roller 12D, and the constitution of the heating belt 12C itself and this belt 1
The nip width when the paper P is nipped is widened by the extension length of 2C.

The heating belt 12C has a cylindrical shape and a diameter of 60 mm and a thickness of 90 μm, and is made of a polyimide belt resin base, and coated with a high-release silicone rubber provided on the outer periphery of the base. With a thickness of 20
It has a surface layer forming an oil carrying layer of 0 μm, has a low heat capacity, and is said to have good thermal responsiveness.

The substrate has a resistance value of 1 × 10 ⁰ to 1 × 10 ^6.
Ω, and the surface layer has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴
It is said to be Ω. The pressure roller 12B is the heating belt 12
It contacts the surface layer forming the peripheral surface of C and rotates in the same direction as the heating belt 12C at the nip portion 16. As will be described later, the fixing device 12 has a resistance applying unit having a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω that applies resistance between the base and the ground.

The resistance applying means is a bias roller 40.
Therefore, even if a voltage is applied to the heating belt 12C, the resistance imparting means has a resistance of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω, and thus 1 × 10 ⁹ to 1 × before reaching the ground.
The heating belt 1 is provided with a resistance of 10 ¹⁴ Ω to prevent the surface layer of the heating belt 12C from being scratched, and at the same time, to reduce leakage current to prevent leakage.
It is intended to prevent the damage generated on the surface layer of 2C from spreading and further prevent electrical noise and influence on the image.

The bias roller 40 is in contact with the surface layer forming the peripheral surface of the heating belt 12C. Bias roller 40
Has a thickness of 1 mm on the surface of an iron cored bar and has a medium resistance (10 ⁵ ~
It is coated with silicon rubber of 10 ⁸ Ω).
The bias roller 40 applies a voltage of -3 kV to the heating belt 12C, but when the image forming apparatus 1 can form a color image, it is -3k when forming a monochrome image.
A voltage of −2 kV can be applied to the heating belt 12C at the time of V, color image formation. The range of voltage applied by the bias roller 40 can be −2 kV to −4 kV. In addition, such a configuration of the heating belt 12C is suitable for color image formation.

The fixing roller 12A has a core metal made of iron and a solid metal, and an elastic layer of silicon rubber, which is a foamed silicon and has a thickness of 6 mm, arranged around the core metal and has a diameter of 30.
mm roller. The core metal is grounded to the ground through a side plate that is a part of the housing 12F of the fixing device 12,
It is grounded. The elastic layer has a resistance value of 1 × 10 ⁹ to 1
It forms a resistance layer of × 10 ¹⁴ Ω. This resistance layer constitutes resistance application means.

Therefore, by forming the resistance applying means by this resistance layer, even if a voltage is applied to the heating belt 12C by the bias roller 40, the resistance of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω is reached before reaching the ground. To prevent damage to the surface layer of the heating belt 12C, and to prevent leakage by reducing the current flowing through such damage to prevent the damage to the surface layer of the heating belt 12C from spreading. Furthermore, it is designed to prevent electrical noise and influence on images.

The tension roller 12E is a roller made of solid iron and has a diameter of 8 mm, the surface of which is nickel-plated. The fixing device 12 has a sliding bearing (not shown) serving as a bearing of the tension roller 12E and serving as a first bearing member made of a PPS-based resin having heat resistance.
The sliding bearing is grounded through a side plate that supports the sliding bearing. That is, the tension roller 12E is grounded via the sliding bearing through the side plate described above. The sliding bearing has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω and constitutes a resistance applying unit.

Therefore, by constituting the resistance applying means by this sliding bearing, even if a voltage is applied to the heating belt 12C by the bias roller 40, the resistance of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω is reached before reaching the ground. To prevent damage to the surface layer of the heating belt 12C, and to prevent leakage by reducing the current flowing through such damage to prevent the damage to the surface layer of the heating belt 12C from spreading. Furthermore, it is designed to prevent electrical noise and influence on images.

The heating roller 12D is a hollow aluminum roller having a thickness of 1 mm, the surface layer of which is coated with Teflon (registered trademark) having conductivity, and the diameter of which is 30 mm. The fixing device 12 has a bearing member (not shown) as a second bearing member that forms a bearing of the heating roller 12D. This bearing member is provided with a PPS heat-resistant resin heat insulating bush disposed at the end of the heating roller 12D in order to prevent a temperature drop at the end of the heating roller 12D, and disposed outside the heat insulating bush. And a metal ball bearing.
The ball bearing is grounded through a side plate that supports the ball bearing. That is, the heating roller 12D is grounded through the above-mentioned side plate via a heat insulating bush and a ball bearing. The heat insulating bush has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω,
It constitutes a resistance applying means.

Therefore, by forming the resistance applying means by the heat insulating bush, even if a voltage is applied to the heating belt 12C by the bias roller 40, the resistance of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω is reached before reaching the ground. Is given
While preventing the surface layer of the heating belt 12C from being damaged, the current flowing through the surface of the heating belt 12C is reduced to prevent leakage, thereby preventing the damage of the surface layer of the heating belt 12C from spreading and further preventing electrical damage. It is designed to prevent noise and effects on images.

The pressure roller 12B is a roller having a diameter of 40 mm, in which an elastic layer having a thickness of 1.5 mm is provided as a surface layer on the surface of an iron cored bar having a thickness of 1 mm.
It has a three-layer structure including a base layer of conductive silicone rubber, an intermediate layer of fluororubber having a thickness of about 30 μm, and a surface layer of high-release silicone rubber having a thickness of about 70 μm.

Inside the pressure roller 12B and the heating roller 12D, a pressure heater 25 and a heater 26, which are a heating source and a heater as a heating means, are provided. Further, the pressure roller 12B and the heating roller 12D are provided on the peripheral surfaces thereof with the thermistors 27 and 2 as temperature detecting means, respectively.
8 is in contact with each other, and the temperature of each of the rollers 12B and 12D is controlled by controlling the energization of the pressure heater 25 and the heating heater 26 based on the detected temperature.

As a result, the temperature of the heating belt 12C is controlled to be substantially uniform at the nip portion 16 at a predetermined fixing temperature, and the paper P carrying the toner image T is passed through the pressure contact area from below in the drawing to cause the heating belt 12C to pass. The toner image T on the paper P is heated, melted, and pressed by the paper etc.
It has become established in.

The fixing device 12 is provided with a coating device 20 for coating the heating belt 12C located on the side in contact with the toner image T with a release agent for offset prevention.
The coating device 20 includes a release agent such as silicone oil (hereinafter,
(Expressed as oil) is applied to the surface of the heating belt 12C so that the unfixed toner forming the toner image T carried on the paper P is less likely to reversely transfer to the surface of the heating belt 12C. It is provided.

The coating device 20 is attached to the housing portion 12F of the fixing device 12. The oil application device 20 includes an oil application unit 20A having an inverted L shape, and the oil application unit 20A is
Support portion 20A1 provided on the upper portion in the shape
The support pin 24 is inserted into the so as to be swingable. The oil application unit 20A is adapted to open the inside of the main body of the fixing device 12 by swinging. A part of the support portion 20A1 is cut out in the circumferential direction of the support pin 24, and the support pin 24 can be inserted and removed through the cutout.

The oil applying unit 20A holds oil for applying to the heating belt 12C, and serves as an oil impregnated pad having a seal part which is closed except for an oil discharge part 20D which will be described later and whose detailed illustration is omitted. Oil holding portion 20C and oil holding portion 20 utilizing osmotic pressure
The oil transporting portion 20B capable of sucking up the oil held in C and the oil sucked up by the osmotic pressure at the position opposite to the oil holding portion 20C in the oil transporting portion 20B, such as the leveling roller 21 An oil discharge portion 20D that is transferred to another member, and a case 20 that covers these
E and.

The coating roller 22 has a diameter of 12 mm,
It is a roller coated with silicon rubber having a thickness of 100 μm. The coating roller 22 is the fixing roller 12
Both ends are pressed against the heating belt 12C toward the center of A at 0.5 kgf. Leveling roller 21
Is a silicon rubber roller having a diameter of 10 mm and a thickness of 1 mm. The leveling rollers are 0.5 kgf at both ends toward the center of the application roller 22.
Is pressed against.

The coating roller 22 contacts the heating belt 12C and is driven to rotate by the heating belt 12C, so that the coating roller 22 rotates in the same direction as the heating belt 12C at a position facing the heating belt 12C. The leveling roller 21 is in contact with the coating roller 22 and is driven to rotate by the leveling roller 22, so that the coating roller 2 is located at a position facing the coating roller 22.
It rotates in the same direction as 2.

Therefore, the leveling roller 21 is provided in the oil discharge portion 20.
The oil transferred from D is supplied to the application roller 22,
The application roller 22 applies the oil supplied from the leveling roller 21 to the heating belt 12C, so that the leveling roller 21
As a result, the oil having a uniform carrying amount in the width direction of the heating belt 12C is applied to the heating belt 12C by the applying roller 22.

For the oil holding portion 20C, it is possible to use a bag-like member capable of containing oil or a pad-like fiber member such as cotton capable of impregnating oil. Oil transport section 2
0B is a member made of a porous or fibrous member,
A material having a contact angle with oil of 90 degrees or less is used. In this embodiment, aramid felt, ceramic paper, or the like is used, and although not shown, an elastic body such as a leaf spring is integrated as a backing member to provide flexibility.

The oil discharge section 20D is the oil transport section 20.
On the side opposite to the oil holding portion 20C in B, the leveling roller 2 is positioned higher than the oil holding portion 20C.
The surface facing the first side is integrated with the oil transport unit 20B. The oil discharger 20D is made of a non-woven fabric made of an aramid / PET mixed material that allows oil to seep out.

The oil discharge portion 20D is the oil holding portion 20.
When the end of the oil transporting portion 20B that is in contact with the C side is the base end, it is located on the swinging end side, and when it comes into contact with the leveling roller 21, the elastic restoring force at the time of bending deformation is used. Then, they are pressed against the leveling roller 21. Specifically, the oil discharger 20D is pressed against the leveling roller 21 at a front width of 1 kgf toward the center of the leveling roller 21. The amount of oil applied to the heating belt 12C is controlled by the pressure between the oil discharge unit 20D, the leveling roller 21, the application roller 22, and the heating belt 12C.

The oil application unit 20A has a wall surface 20 facing the oil holding portion 20C arranged in the lower space.
A2 can be attached and detached, and the oil holding portion 20C can be sealed by being attached to the oil application unit 20A side by fastening or the like. The wall surface 20A2 is removed for the convenience of replacing the oil holding portion 20C after the oil application unit 20A is removed from the housing 12F of the fixing device 12. Further, a grip portion 20A3 for hooking a hand when swinging the oil application unit 20A is formed on the lower outer surface.

For the sake of convenience, a locking pin 20A4 shown by a solid line in FIG. 2 is integrally provided on a side portion of the oil applying unit 20A. The locking pin 20A4 is shown by a solid line in FIG. 2 for convenience. It can be engaged with and disengaged from a locking portion 12F1 provided on a certain housing 12F side.

When the locking pin 20A4 is engaged and locked to the locking portion 12F1, the oil applying device 20 is positioned with respect to the fixing device 12. The oil applicator 20 is positioned such that the oil discharger 20D can be pressed against the leveling roller 21 by the elastic restoring force of the flexing deformation of the oil transporting part 20B with respect to the leveling roller 21. The oil is smoothed out by roller 2
Will be handed over to 1.

The felt member 23 is fixedly installed at a fixed position on the main body side of the fixing device 12, and the oil application unit 20A is provided.
The position is maintained regardless of whether the fixing device 12 is rocked or detached. When the fixing device 12 is assembled, or at least the fixing device 1 is attached to the felt member 23.
By the time the use of No. 2 is started, 300 cs of oil has been impregnated in advance. The oil is the same as that held in the oil holding portion 20C.

Therefore, the coating device 20 is the fixing device 1
2, the support portion 20A1 is inserted into the support pin 24 located on the housing 12F side, and the locking pin 20A4 located on the swinging end side with the support pin 24 as a fulcrum is mounted on the housing 12F side locking portion 12F1. By engaging with each other, the oil discharge portion 20D is positioned so as to be in pressure contact with the leveling roller 21. The pressure contact force to the leveling roller 21 is the oil transport section 20.
It is maintained by the elastic restoring force at the time of flexural deformation of B.

In the oil applying device 20, the oil transport section 2
It is possible to suck the oil 0B impregnated in the oil holding portion 20C toward the oil discharge portion 20D by osmotic pressure and deliver it to the leveling roller 21 at the oil discharge portion 20D. The oil discharge portion 20D is the oil holding portion 20C.
Since it is located at a position higher than the above and in a position opposed to the weight direction, it is possible to prevent an excessive supply state from exceeding the suction amount due to the osmotic pressure.

When fixing is repeated, although the application of the oil is well controlled by the application device 20, foreign matter such as paper dust adhering to the paper P or a part of the toner constituting the toner image T is heated by the heating belt. May adhere to 12C. In this case, the foreign matter applied through the heating belt 12C is not applied to the coating device 2
Although it moves to the inside of 0, the foreign material is blocked by the felt member 23 and prevented from reaching the oil discharge portion 20D.

Therefore, the oil is the oil discharge portion 20D.
After that, the oil is not applied to the heating belt 12C through the portions of the leveling roller 21 and the application roller 22 that are not affected by foreign matter, so that the oil application performance does not deteriorate. Therefore, the adherence of foreign matter to the heating belt 12C and the like is well suppressed over time, and the fixing performance of the fixing device 12 is maintained.

When the fact that the amount of oil in the oil holding portion 20C has reached a predetermined amount or less is detected by, for example, a change in the rotational state affected by the sliding state of the leveling roller or the number of used sheets, the oil application unit 20A is replaced. The oil coating unit 20A can be replaced by the support portion 20A.
The support pin 24 inserted in 1 is used as a fulcrum to swing the lower part in a lifting direction. Oil application unit 20A
When oscillates, the locking pin 20A4 disengages from the locking portion 12F1 and is pulled out in the direction of the notch of the support portion 20A1 to remove the coating device 20 from the fixing device 12.

The oil applying unit 20A is attached to the fixing device 12.
When the oil holding unit 20C is removed from the side, the oil holding unit 20C tilts.
A unit main body in A and wall surface 20A that can be attached to and detached from the unit main body
Since it is hermetically sealed with No.2, it does not fall off and the oil itself is prevented from spilling or dripping. The oil application unit 12A removed from the fixing device 12 is
The oil discharger 20D is exposed to the outside.

Further, even during such swinging and attaching / detaching operations, the felt member 23 is held in a fixed position on the main body of the fixing device 12, so that the foreign matter blocked by the felt member 23 is It can be prevented from falling and contamination inside the device can be prevented.
Further, due to such an operation, the dammed foreign matter does not move to the position where the oil discharger 20D is disposed and does not affect the fixing after returning to the oil application unit 12A.

Therefore, the oil dripping and spilling at the time of replacement can be surely prevented by a simple structure in which the oil application unit 20A has a unit structure.
In particular, since the oil holding portion 20D has a pad structure, it is possible to more reliably prevent accidental liquid dripping. Even when the bag structure is used instead of the pad structure, only the portion where the oil transporting portion 20B comes into contact is opened, so that the oil can be prevented from spilling.

As shown in FIG. 3, among the components of the fixing device 12, at least the fixing roller 12A, the pressure roller 12B, the heating belt 12C, the heating roller 12D, the tension roller 12E, the pressure heater 25, and the heater 26 are used. A fixing belt unit 41 as a fixing unit is configured, and the fixing belt unit 41 is detachable from the fixing device 12 and the main body of the image forming apparatus 1. In FIG. 3, reference numeral 42 indicates a guide plate as a guide means for guiding the paper P toward the nip portion 16. The guide plate 42 is not shown in other figures.

In the fixing belt unit 41, the oil applying unit 20A swings with respect to the main body of the fixing device 12 and the inside of the main body of the fixing device 12 is opened, or the oil applying unit 20A is removed from the fixing device 12. Since the coating roller 22 is separated from the fixing belt 12C, the fixing roller 12 can be easily attached to and detached from the fixing apparatus 12 main body and the image forming apparatus 1 main body.

The voltage applying structure to which the present invention is applied, the bias applying structure having the voltage applying structure, and the image forming apparatus having the voltage applying structure have been described above, but the bias is such that the toner forming the toner image T is pressed against the paper P. The voltage applied to the bias roller 40 does not have to have the same polarity as the toner as long as a bias is applied to prevent the toner from being disturbed.

In the above example, the case where the resistance applying means has the resistance layer of the first roller, the first bearing member and the second bearing member has been described. However, the resistance layer of the first roller, the first bearing member, and the second bearing member may be provided alone, or the resistance layer of the first roller may be provided. Only one of the first bearing member and the second bearing member may be provided.

[0069]

According to the present invention, there is provided a rotating endless fixing belt, and a pressure member which contacts the peripheral surface of the fixing belt and rotates in the same direction as the identification fixing belt in the contact area with the identification fixing belt. A fixing device that has a voltage applying unit that contacts the peripheral surface of the fixing belt and applies a voltage to the identification fixing belt, and that passes the recording medium carrying the toner image through the contact region to fix the toner image on the recording medium. In the above, the fixing belt is
A base body having a resistance value of 1 × 10 ⁰ to 1 × 10 ⁶ Ω, and a surface layer having a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω, which is arranged on the outer periphery of the base body and is in contact with the voltage applying means. Having a resistance value of 1 × 10, which provides resistance between the base and the ground.
Since it has a resistance applying means of ⁹ to 1 × 10 ¹⁴ Ω, even if a voltage is applied to the surface layer of the fixing belt by the voltage applying means,
Since the resistance applying means has a resistance of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω, 1 × 10 is obtained before reaching the ground.
A resistance of ⁹ to 1 × 10 ¹⁴ Ω can be imparted to prevent the surface layer of the fixing belt from being scratched, and at the same time, the current flowing through the scratch can be reduced to prevent leakage and thus to the surface layer of the fixing belt. To provide a fixing device capable of preventing spreading of a scratch that has occurred, further preventing electrical noise and influence on an image, and having high safety and capable of obtaining a good fixed image. You can

The first roller has a first roller around which a fixing belt is wound, and the first roller has a metal core which is grounded and a resistance value of 1 ×, which is arranged on the outer periphery of the metal core. 10 ⁹
And a resistance layer having a resistance of 1 × 10 ¹⁴ Ω.
If a resistance layer is provided, a metal cored bar and a layer forming the outer periphery of the cored bar, which are usually provided in a belt fixing device, are used, and the resistance imparting means is formed by using this layer as a resistance layer. As a result, even if a voltage is applied to the surface layer of the fixing belt by the voltage applying unit, 1 × 10 ⁹ to
A resistance of 1 × 10 ¹⁴ Ω can be imparted to prevent damage to the surface layer of the fixing belt, and at the same time, the current flowing through the damage is reduced to prevent leakage, which is caused on the surface layer of the fixing belt. It is possible to provide a fixing device that can prevent the spread of scratches, can prevent electric noise and influence on an image, and can obtain a fixed image with high safety.

There is provided a second roller around which the fixing belt is wound, and a grounded first bearing member which forms a bearing of the second roller, and the second roller is made of metal, 1
Bearing member has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴ Ω, and if the resistance imparting means has the first bearing member, it may be provided in the belt fixing device. The roller and the bearing of this roller are used, and by using this bearing as a resistance to form a resistance applying unit, even if a voltage is applied to the surface layer of the fixing belt by the voltage applying unit, 1 × is reached until the ground is reached. A resistance of 10 ⁹ to 1 × 10 ¹⁴ Ω can be imparted to prevent the surface layer of the fixing belt from being scratched, and the current flowing through the scratch can be reduced to prevent leakage, thereby preventing the surface layer of the fixing belt. To provide a fixing device capable of preventing the spread of scratches generated on the surface, preventing electrical noise and the influence on the image, and being capable of obtaining a good fixed image with high safety. Can .

The fixing roller has a third roller for heating the identification fixing belt wound around the fixing belt, and a second bearing member forming a bearing of the third roller. The third roller is made of metal. And the second bearing member has a resistance value of 1 × 10 ⁹ to
1 × 10 ¹⁴ Ω, and if the resistance imparting means has a second bearing member, a roller for heating the fixing belt, which is usually provided in the belt fixing device, and a bearing of this roller, By configuring the resistance applying means using this bearing as a resistance, even if a voltage is applied to the surface layer of the fixing belt by the voltage applying means, it becomes 1 before reaching the ground.
A resistance of × 10 ⁹ to 1 × 10 ¹⁴ Ω can be imparted to prevent the surface layer of the fixing belt from being scratched, and at the same time, the current flowing through the scratch can be reduced to prevent leakage. (EN) A fixing device capable of preventing the spread of scratches on the surface layer, preventing electrical noise and the influence on an image, and providing a highly secure and favorable fixed image. be able to.

Since the present invention is a fixing method in which fixing is performed by using the fixing device according to any one of claims 1 to 4, the fixing is performed by using the fixing device that achieves each of the above-mentioned effects, and safety is ensured. It is possible to provide a fixing method capable of obtaining an excellent fixed image.

Since the present invention resides in an image forming apparatus having the fixing device according to any one of claims 1 to 4, the fixing device having the above-mentioned effects is provided, and a high-quality image can be obtained safely. It is possible to provide an image forming apparatus capable of performing the above.

[Brief description of drawings]

FIG. 1 is a schematic view of a fixing device to which the present invention is applied and an image forming apparatus having the fixing device.

FIG. 2 is a schematic view of the fixing device shown in FIG.

FIG. 3 is a schematic view of a main part of the fixing device shown in FIG.

[Explanation of symbols]

1 Image forming device 12 Fixing device 12A Fixing roller 12 as first roller 12B Pressure roller as pressure member 12C Heating belt as fixing belt 12D Heating roller as third roller 12E Tension roller as second roller 16 Contact area 40 voltage applying means P recording medium T toner image

Claims (6)

[Claims] 1. A rotating endless fixing belt, a pressure member that abuts on a peripheral surface of the fixing belt and rotates in the same direction as the identification fixing belt in a contact area with the identification fixing belt, and a circumference of the fixing belt. A fixing device that has a voltage applying unit that abuts against a surface and applies a voltage to the identification fixing belt, and passes a recording medium carrying a toner image through the contact area to fix the toner image on the recording medium. The belt has a resistance value of 1 × 10 ⁰ to 1 × 10 ⁶ Ω.
And substrate, said voltage application means is disposed on the outer periphery of the base body abuts, resistance and a surface layer of ^{1 × 10 9 ~1 × 10 1} 4 Ω, the resistance between the base and ground Resistance is 1
× fixing apparatus characterized by having a resistance applying means ^{10 9 ~1 × 10 1 4 Ω} . 2. The fixing device according to claim 1, further comprising a first roller around which the fixing belt is wound, the first roller being a grounded metal cored bar and a cored bar made of metal. A resistance value of 1 × 10 ⁹ to 1 × 10 arranged on the outer periphery
^And a resistance layer of ¹⁴ Ω, and the resistance applying unit includes the resistance layer. 3. The fixing device according to claim 1, further comprising a second roller around which the fixing belt is wound, and a grounded first bearing member which forms a bearing of the second roller. The second roller is made of metal, and the first bearing member has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴
Ω, and the resistance applying unit includes a first bearing member. 4. The fixing device according to claim 1, wherein the fixing roller is wound around the third roller for heating the identification fixing belt, and the second roller forming a bearing of the third roller. A bearing member, the third roller is made of metal, and the second bearing member has a resistance value of 1 × 10 ⁹ to 1 × 10 ¹⁴
Ω, and the resistance applying unit has a second bearing member. 5. A fixing method for fixing by using the fixing device according to claim 1. 6. An image forming apparatus having the fixing device according to claim 1. Description: