JPH07248696A - Fixing device - Google Patents

Abstract

PURPOSE:To stabilize control and rotational control of a film in the axial direction after durability test so as to mask an image stable by specifying the axial direction Rz of the surface of a driving roller. CONSTITUTION:A fixing film 7 formed like an endless belt is wound and made tense among a leftside driving roller 8, a rightside follower roller 9 and a low thermal capacity line heating body 1 as a heating body disposed on a lower part between both rollers 8 and 9. This follower roller 9 also serves as the tension roller of the fixing film 7 formed like an endless belt and the fixing film 7 is rotary-driven without wrinkling, winding or speeding down with a specified circumferential speed in the clockwide direction following the rotary- driving of the driving roller 8 in the clockwise direction, that is,with the same circumferential speed as a speed for carrying recording paper P on whose upper surface a nonfixed toner image Ta is carried from an image forming part side. The driving roller 8 is made of a silicone rubber having a specified thickness on its core metal and the surface Rz of the axial direction is 2mum<Rz<11mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material carrying a visible image (hereinafter referred to as a toner image) to be heat-fixed adhered to a heating body through a film so that the heating body passes through the film. The present invention relates to a film heating type fixing device that applies heat energy to a recording material to heat and fix a toner image.

This apparatus is suitable for electrophotography, electrostatic recording, magnetic recording, etc. in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, an image display (display) device and a recording machine. Using a toner made of a heat-meltable resin or the like by an image forming process means, a direct method or an indirect method (directly or indirectly) is applied to the surface of a recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) as an image carrier. It can be utilized as an image fixing device that heats and fixes an unfixed toner image corresponding to the target image information formed by the (transfer) method as a permanently fixed image on the surface of the recording material carrying the image.

[0003]

2. Description of the Related Art Conventionally, as a heating type fixing device, an unfixed toner image is formed by a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. A fixing device of a heat roller fixing system that heats the recording material while nipping and transporting the recording material is widely used.

However, the fixing device of the heat roller fixing system firstly requires a time until the temperature rises to a predetermined temperature (time for prohibiting the image forming operation), that is, a so-called wait time, and secondly, a heat capacity. It requires relatively large electric power, and thirdly, the rotating roller has a high roller temperature, so a heat-resistant special bearing is necessary. In addition, there are drawbacks such as the need for a protective member, and the fifth problem is that the recording material wraps around due to the roller fixing temperature and curvature, causing jamming.

Therefore, as a fixing device of the heating system which does not have the above-mentioned drawbacks, recently, the fixing device of the film heating system as described above has attracted attention, and research and development for its practical use have been advanced. .

According to the applicant's previous proposal, for example, Japanese Patent Laid-Open No.
The system, apparatus, etc. disclosed in Japanese Patent Laid-Open No. 3-313182 belong to this, and a thin heat-resistant film (sheet), a moving driving means for the film, and a fixedly supporting one side of the film with the film inside are arranged. And a pressing member arranged on the other surface side so as to face the heating body and to bring the developed image bearing surface of the recording material to be image-fixed into close contact with the heating body via the film. The film is moved at least at the same speed in the forward direction as the recording material to be image-fixed, which is conveyed and introduced between the film and the pressure member at the time of image fixing, and the heating moving body is sandwiched between the film and the heating member. By passing through a fixing nip portion formed by pressure contact between a pressure member and a pressure member, the developed image bearing surface of the recording material is heated by the heating body through the film to heat the developed image (unfixed toner image). Apply energy to soften and melt And then separating the film and the recording material, or a heating means or apparatus which is based on the toner to separate the film and the recording material after cooling and solidifying.

As the heating element, a linear or strip-like shape is formed on the side of the film contact surface of a horizontally long heat-resistant, insulating, low-heat-capacity heater substrate whose longitudinal direction is the width direction of the film. A heating element having a low-heat-capacity energizing heating resistor (heating element) is used, and the heating element generates heat when electric power is supplied between both ends of the heating element. The temperature of the entire body rapidly rises, and the heat of the heating body is applied to the recording material via the film.

The temperature control of the heating element is carried out by a temperature sensor provided on the heating element, a microcomputer of the image forming apparatus main body and a heating element driving (energizing heat generation) circuit, and the temperature is controlled to a predetermined fixable temperature. It Although the heating element is at a high temperature, the film is driven to move on the heating element at a predetermined speed at least when the heating element generates heat, so local thermal deformation of the film does not occur and stable image fixing is performed. Is executed.

A drive roller cleaning member for cleaning the roller surface is in contact with the drive roller. As a result, with long-term use, abrasion powder on the inner surface of the fixing film that adheres to the surface of the driving roller is removed, the coefficient of friction between the fixing film and the surface of the driving roller decreases, and eventually slipping occurs. It became possible to drive the film stably for a long time.

[0010]

However, in the above-mentioned conventional example, when the axial direction Rz of the driving roller surface is large, the driving roller surface is rubbed against the fixing film or the driving roller cleaning member due to long-term use. Wears and the surface condition of the drive roller changes greatly from the initial state of use, the speed at which the fixing film moves in the axial direction changes, and control of the fixing film in the axial direction becomes unstable, Finally, there was a problem that the fixing film slipped completely.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to improve the durability and reliability of this type of fixing device.

In order to solve the above-mentioned problems, the present invention comprises a fixing film, a drive roller for driving and driving the fixing film, and a heating member and a pressing member which are in pressure contact with the fixing film interposed therebetween. The fixing nip together with the fixing film that runs by introducing the recording material carrying the unfixed toner image between the fixing film and the pressing member in the fixing nip portion formed by pressing the heating member and the pressing member. In a fixing device in which heat energy is applied from a heating element to a recording material through a fixing film to heat and fix a toner image by moving the sheet through a portion, the axial direction Rz of the surface of the drive roller is 2 μm.
<Rz <11 μm.

[0013]

【Example】

(Embodiment 1) (1) Example of image device (FIG. 5) FIG. 5 shows a schematic configuration of an example of an image forming device using a fixing device 60 described later according to the present invention.

The image forming apparatus of this embodiment is a fixed original-moving optical system type, a rotary drum type, or a transfer type electrophotographic copying apparatus.

When the original 19 is placed on the fixed original glass 20 as required and the required copying conditions are set and the copy start key is pressed, the photosensitive drum 39 is rotated by a predetermined amount in the clockwise direction indicated by the arrow. It is driven to rotate at speed.

Further, the light source 21 (22 is a reflection shade) and the first mirror 23 move forward along the lower surface of the original table glass 20 from the home position on the left side of the glass to the right side of the glass at a predetermined speed V, and the second mirror. When the third mirrors 24 and 25 move forward in the same direction at a speed of V / 2, the downward image surface of the document 19 placed on the document table glass 20 is illuminated and scanned from the left side to the right side, and the illumination scanning is performed. The light reflected from the document surface is formed by the imaging lens 2
9. Imaging exposure (slit exposure) is performed on the surface of the rotating photosensitive drum 39 through the fixed fourth to sixth mirrors 26, 27, and 28.

Prior to this exposure, the surface of the rotating photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30, and the above-mentioned exposure is performed on this charged surface. Then, an electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the drum 39. Photosensitive drum 3
The electrostatic latent image formed on the nine surfaces is visualized as a toner image by the developing roller 32 of the developing device 31.

On the other hand, a transfer material sheet P as a recording material is fed by a paper feeding means (not shown), and is introduced into a transfer portion between the drum 39 and the transfer charger 34 at a predetermined timing through a guide 33. Drum 3 by receiving a transfer corona
The toner visible image on the surface of the drum 39 in contact with the sheet 9 is sequentially transferred to the surface of the sheet P.

The sheet P that has passed through the image transfer portion is sequentially separated from the surface of the drum 39 by a separating means (not shown) (for example, a separating belt arranged at the end of the drum), and is discharged by the discharging needles 35 to remove the charges on the back surface. The sheet is introduced into the fixing device 60 by the conveying unit 38 and the guide 18, undergoes toner image fixing as will be described later, and is discharged out of the apparatus as an image formed product.

The surface of the drum 39 after transfer is the cleaning device 3
A cleaning blade 37 of No. 6 removes stains such as residual toner to form a clean surface, and is repeatedly used for image formation.

When the moving optical members 21 to 25 that have moved forward have reached a predetermined forward movement end point, they are returned to the initial home position and return to the first home position, and wait until the start of the next copy cycle (back of the optical system). Process).

(2) Example of fixing device a) Device configuration FIG. 1 is a side view of an example of a fixing device 60 according to the present invention,
FIG. 2 is a rear view, and FIG. 3 is a layer structure model diagram of a fixing film.

Reference numeral 7 denotes an endless belt-shaped fixing film, which includes a left driving roller 8, a right driven roller 9 and
A low-heat-capacity linear heating element 1 as a heating element disposed below the rollers 8 and 9 is stretched around the three members 8 and 9-1.

The driven roller 9 also serves as a tension roller for the endless belt-shaped fixing film 7, and the fixing film 7 is rotated at a predetermined peripheral speed in the clockwise direction as the driving roller 8 is driven in the clockwise direction, that is, the image forming portion. The unfixed toner image Ta conveyed from the side is rotationally driven at the same peripheral speed as the conveying speed of the recording material P carrying the upper surface without wrinkles, meandering, or speed delay. The fixing film 7 is also controlled to move in the axial direction by means (not shown).

Numeral 10 is a pressure roller having a rubber elastic layer 12 having a good releasability, such as silicon rubber, as a pressure member. The pressure roller 10 has the lower film portion of the endless belt-shaped fixing film 7 sandwiched therebetween. The lower surface of the heating element 1 is pressed against the lower surface of the heating element 1 by a biasing means (not shown) with a total pressure of 4 to 7 kg, and the shaft 11 is centered counterclockwise in the forward direction of the conveyance direction of the recording material P. Rotate to.

The heating element 1 is a linear heating element having a low heat capacity and having a longitudinal direction in a direction crossing the plane moving direction of the film 7 (width direction of the film), and includes a heater substrate 3, an energization heating resistor (heating element) 4, It is composed of a temperature measuring element 5 and the like, and is fixedly supported by being attached and held on the heater support 2.

The heater support 2 fixes the heating body 1 to the fixing device 60.
In addition, it has heat insulating properties, high heat resistance, and rigidity for heat-insulating and supporting the image forming apparatus. For example, PPS (polyphenylene sulfide), PAI (polyamide imide), PI.
It can be made of high heat resistant resin such as (polyimide), PEEK (polyether ether ketone), liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass, or the like.

The heater substrate 3 is a member having heat resistance, insulation, and low heat capacity, and as an example, the thickness is 1.0 mm and the width is 16 mm.
-Alumina substrate having a length of 340 mm.

The heating element 4 is provided along the length of the lower surface of the substrate 3 (on the side facing the film 7) along the longitudinal direction, for example, Ag / P.
An electric resistance material such as d (silver-palladium) or Ta ₂ N is applied by screen printing to a thickness of about 10 μm and a width of 1 to 3 mm, and a heat-resistant glass 6 as a surface protective layer is applied on the surface of about 10
μm coated.

As an example, the temperature measuring element 5 has a low heat capacity such as a Pt film provided by coating by screen printing or the like on substantially the central portion of the upper surface of the substrate 3 (the surface opposite to the surface on which the heating element 4 is provided). This is a resistance temperature detector. Alternatively, as the temperature detecting element, a thermistor having a low heat capacity may be arranged in contact with the substrate 3.

In the case of the heating element 1 of this example, the linear or strip heating element 4 is energized from both ends in the longitudinal direction,
The heating element 4 is made to generate heat over substantially the entire length. Power is AC1
It is 00 V, and the energization power is controlled by controlling the energizing phase angle by an energization control circuit (not shown) including a triac according to the detected temperature of the temperature detecting element 5.

The fixing film 7 has heat resistance, releasability, durability, etc., and generally has a total thickness of 100 μm or less, preferably 40.
A single layer or a composite layer film having a thickness of less than or equal to μm can be used.

FIG. 3 is a schematic diagram of the layer constitution of an example of the composite layer film, and this example is a two-layer constitution film. 7b is a heat-resistant layer as a base layer of the fixing film,
Reference numeral a is a release layer laminated on the outer surface (surface facing the toner image) of the heat resistant layer 7b.

The heat-resistant layer 7b is a high heat-resistant resin film such as polyimide, polyetheretherketone (PEEK), polyethersulfone (PES), polyetherimide (PEI) or polyparabanic acid (PPA).
Metals such as Ni, SUS, and Al that have excellent strength and heat resistance can be used.

The release layer 7a is made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene) / PFA / FEP,
Silicone resin or the like is preferable (PTFE in this example). The resistance value of the surface of the fixing film 7 can be reduced by mixing a conductive agent such as carbon black, graphite, conductive whiskers or the like into the release layer 7a. Accordingly, the toner contact surface of the fixing film 7 can be prevented from being charged.

The release layer 7a is laminated on the heat-resistant layer 7b by adhesive lamination of the release layer film, lamination of the release layer material by a film-forming technique such as electrostatic coating (coating), vapor deposition, and CVD, and the heat-resistant layer material. 2 by co-extrusion of release layer material
It can be performed by forming a layer film.

Reference numeral 13 is a drive roller cleaning member for cleaning the surface of the drive roller. The drive roller cleaning member 13 has a holder made of heat-resistant resin or sheet metal and a length of 2.5 m.
m, pile diameter 20d / 2f, and density 500 loops / inch.

B) Fixing Execution Operation The image forming apparatus (FIG. 5) of the above-described example performs an image forming operation in response to an image forming start signal and is conveyed to the fixing device 60. Sheet P
Is guided by the guide 18 and enters between the fixing film 7 and the pressure roller 10 at the pressure contact portion (fixing nip portion) between the heating body 1 and the pressure roller 10, and the unfixed toner image surface becomes the sheet P. The heating element 1 is brought into close contact with the lower surface of the fixing film 7 which is rotated in the same direction at the same conveying speed as that of the heating member 1 and is overlapped with the fixing film 7 without causing surface misalignment, wrinkling or deviation.
And the pressure roller 10 and the pressure roller 10 are pressed against each other.

Since the heating element 1 is electrically heated at a predetermined timing by the image formation start signal, the toner image Ta
Is heated at the press contact portion and becomes a softened / melted image Tb.

In the fixing film 7, the heater support 2 has an edge portion S (having a radius of curvature of about 2 mm) having a large curvature.
The traveling direction turns at a steep angle (the bending angle θ is approximately 45 °). Therefore, the sheet P conveyed through the pressure contact portion while being overlapped with the fixing film 7 is curvature-separated from the fixing film 7 at the edge portion S, and is discharged to the discharge tray. By the time the paper is discharged, the toner is sufficiently cooled and solidified and is in a state of being completely fixed on the sheet P (toner image Tc).

In the present example, the heat capacity of the heating element 4 and the substrate 3 of the heating element 1 is small, and these are the support 2
Since it is adiabatically supported by, the surface temperature of the heating element 1 at the pressure contact portion rises to a sufficiently high temperature with respect to the melting point of toner (or the temperature at which it can be fixed on the sheet P) in a short time.
It is not necessary to raise the temperature of the heating element 1 in advance (so-called standby temperature adjustment), energy can be saved, and the temperature rise inside the machine can be prevented.

C) Rz of driving roller The driving roller used in this example is made of silicon rubber having a thickness of 0.5 mm on the surface of the core metal, and the surface Rz in the axial direction is 2 μm <Rz <11 μm. Has become. Rz
As for the measuring method, SE-330 manufactured by Kosaka Laboratory is used.
0, Stylus R2μm diamond, measuring length 2.5m
m, feed speed 0.1 mm / sec, vertical magnification 20
It is 00 times.

FIG. 4 shows the results of an endurance test when the Rz drive roller measured by the above measuring method was used.
As can be seen from these results, by setting the axial surface Rz of the drive roller to 2 μm <Rz <11 μm, the surface is not scraped after the endurance, and the axial control of the film is stabilized.

(Embodiment 2) In this embodiment, the circumferential direction Rz of the drive roller surface is set to 2 μm <Rz <15 μm.

Although the movement control of the fixing film in the axial direction is stable by the first embodiment, the rotational driving of the fixing film is also stable by this embodiment. That is, if the circumferential direction Rz of the surface of the drive roller changes after the initial use after long-term use, the coefficient of friction in the circumferential direction between the fixing film and the drive roller also changes, and stable control cannot be performed. .

Further, according to Examples 1 and 2, abrasion of the surface of the driving roller after endurance is completely eliminated, and the abrasion powder adheres to the surface of the heater or the holder to deteriorate the image, or the fixing film and the heater or the holder. It can completely prevent clinging.

(Embodiment 3) In this embodiment, Rmax-Rz <6 μm in the axial direction of the surface of the driving roller is set. By doing so, variations in the axial roughness of the drive roller surface are eliminated. That is, if the rubber on the surface is locally blown off, that portion is largely scraped after the endurance, and the scraped rubber adheres to the heater surface and the holder through the film, and deteriorates the image. The present invention solves such a problem.

[0048]

As described above, according to the present invention,
The control of the axial direction of the film after endurance is stable, the rotation control of the film after endurance is stable, and further local abrasion of the rubber on the surface of the drive roller is prevented, and the image can be stabilized.

[Brief description of drawings]

FIG. 1 is a side view of a fixing device.

FIG. 2 is a rear view of the fixing device.

FIG. 3 is a layer configuration diagram of a fixing film.

FIG. 4 is a table for explaining the first embodiment.

FIG. 5 is a schematic diagram of an image forming apparatus.

[Explanation of symbols]

 1 heating element 7 fixing film 8 drive roller 10 pressure roller 13 cleaning brush

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichiro Toyohara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A fixing film, a driving roller for driving and driving the fixing film, and a heating member and a pressing member that press-contact with the fixing film interposed therebetween, and the heating member and the pressing member sandwiching the fixing film. The recording material carrying the unfixed toner image is introduced between the fixing film and the pressure member in the fixing nip portion formed by the pressure of In a fixing device that applies heat energy from a body to a recording material through a fixing film to heat and fix a toner image, an axial direction Rz of the surface of the drive roller is 2 μm <Rz <1.
A fixing device having a size of 1 μm. 2. The fixing device according to claim 1, further comprising a cleaning member that cleans the drive roller. 3. The circumferential direction Rz of the surface of the drive roller is 2
2. The relationship: μm <Rz <15 μm.
The fixing device described. 4. The axial direction Rmax of the surface of the drive roller
The fixing device according to claim 1, wherein −Rz is Rmax−Rz <6 μm.