JP2002093565A - Heating device and image forming device - Google Patents

Abstract

[PROBLEMS] To reduce the deformation of a film in a fixing nip portion of a heating device of an electromagnetic induction heating system as much as possible, to reduce curling and to reduce fatigue due to repeated deformation of the film due to durability. . A fixing film, a film guide member for guiding the fixing film, and a film guide member.
To the fixing nip N
A heating roller having a pressure roller 10 for forming a recording medium P and an exciting coil 12 for heating the recording material P conveyed in the fixing nip portion N while moving the fixing film 9 by heating the fixing film 9. A fixing nip portion N of the guide member 11 against which the pressure roller 10 is pressed through the fixing film 9.
Has a continuous curvature convex in the direction of the pressure roller 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus of a film heating type for heating a recording material in close contact with a heat-resistant film which moves while being guided by a guide member, and an electrophotographic, static heating apparatus. The present invention relates to an image forming apparatus provided as a heating device in an appropriate image forming process such as electronic recording.

[0002]

2. Description of the Related Art Here, an image heating apparatus (fixing apparatus) for heating and fixing a toner image on a recording material in an image forming apparatus such as a copying machine or a printer will be described as an example.

In an image forming apparatus, a recording material (transfer material sheet, electrofax sheet, electrostatic recording paper, OHP sheet, printing) is formed by an appropriate image forming process means such as an electrophotographic process, an electrostatic recording process, and a magnetic recording process. A heat roller is used as a fixing device for heating and fixing an unfixed image (toner image) of target image information formed and carried on a transfer method or a direct method on paper or format paper as a permanently fixed image T on a recording material surface. Type devices were widely used. In recent years, a film heating type apparatus which is advantageous for energy saving and shortening of wait time has been put to practical use. Similarly, an electromagnetic induction heating system has been proposed.

A) Heat roller type fixing device The heat roller type fixing device has, as a basic configuration, a pressure contact roller pair of a fixing roller (heating roller) and a pressure roller. The roller pair is rotated, and a recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced into a fixing nip portion, which is a mutual pressure contact portion of the roller pair, and nipped and conveyed,
The unfixed toner image is heat-pressure fixed on the surface of the recording material by the heat of the fixing roller and the pressing force of the fixing nip.

[0005] The fixing roller generally has a hollow metal roller made of aluminum as a base (core metal), and a halogen lamp as a heat source is inserted and disposed in the inner space thereof. The power supply to the halogen lamp is controlled to control the temperature so that the predetermined fixing temperature is maintained.

In particular, as a fixing device of an image forming apparatus for forming a full-color image in which a capability of sufficiently heating and melting a maximum of four toner image layers to mix colors is required, a core metal of a fixing roller needs to have a high heat capacity. In addition, a rubber elastic layer for wrapping the toner image around the core metal and uniformly melting the toner image is provided, and the toner image is heated via the rubber elastic layer.

Further, there is a configuration in which a heat source is also provided in the pressure roller to heat and control the temperature of the pressure roller.

However, in the heat roller type fixing device, the heat capacity of the fixing roller is large even if the halogen lamp, which is a heat source, is turned on at the same time when the power of the image forming apparatus is turned on. It takes a considerable waiting time (wait time) until the temperature rises to a predetermined fixable temperature from the state in which the fixing is performed, and lacks quick startability.

Further, the image forming apparatus is in a standby state (non-image output) so that the image forming operation can be performed at any time.
Even in this case, it is necessary to energize the halogen lamp to maintain the fixing roller in a predetermined temperature control state, and there is a problem that power consumption is large.

In the case of a fixing device having a particularly large heat capacity, such as the fixing device of the above-described full-color image forming apparatus, a delay occurs between the temperature control and the temperature rise of the fixing roller surface. Problems such as uneven gloss and offset have occurred.

B) Fixing device of film heating system A fixing device of the film heating system is disclosed in, for example,
Japanese Patent Application Laid-Open No. 13182, Japanese Patent Application Laid-Open No. 2-1577878, Japanese Patent Application Laid-Open No. 4-44075, Japanese Patent Application Laid-Open No. 4-204980, and the like.

That is, a fixing nip portion is formed by sandwiching a heat-resistant film (fixing film) between a ceramic heater as a heating means and a pressing roller as a pressing member. A recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced between the pressure roller and the recording material, and the recording material is nipped and conveyed together with the fixing film to fix the heat of the ceramic heater in the fixing nip portion. The unfixed toner image is applied to the recording material via the film, and the unfixed toner image is hot-press fixed on the recording material surface by the pressing force of the fixing nip portion.

This fixing film heating type fixing device is
An on-demand type device can be configured using a ceramic heater and a member having a low heat capacity as a fixing film, and only when the image forming apparatus performs image formation, power is supplied to the ceramic heater as a heat source to generate heat to a predetermined fixing temperature. In this case, there is an advantage that the waiting time from the power-on of the image forming apparatus to the image forming executable state is short (quick start property), and the power consumption during standby is significantly small (power saving).

However, a full-color image forming apparatus requiring a large amount of heat or a fixing device for a high-speed model has a calorific point.

C) Fixing Device of Electromagnetic Induction Heating System JP-A-51-109736 discloses an induction heating fixing device in which current is induced in a fixing roller by magnetic flux and heat is generated by Joule heat. This achieves a more efficient fixing process than a heat roller type fixing device using a halogen lamp as a heat source by directly generating heat in the fixing roller by utilizing the generation of an induced current.

In the fixing device of the electromagnetic induction heating system,
The fixing process is performed by causing the cylindrical fixing film itself as the rotating body of electromagnetic induction heat generation to generate heat by the alternating magnetic flux generated by the exciting coil as the magnetic field generating means.

FIG. 11 shows the configuration of a conventional fixing device of the electromagnetic induction heating type.

Reference numeral 109 denotes a cylindrical fixing film having an electromagnetic induction heating layer (a conductor layer, a magnetic layer, and a resistor layer) and serving as an electromagnetic induction heating rotating body.

Reference numeral 111 denotes a film guide member having a trough-like shape with a substantially semi-circular cross section. The cylindrical fixing film 109 is loosely fitted outside the film guide member 111.

The magnetic field generating means has an exciting coil 112 and magnetic cores (core materials) 113a and 113b forming a T-shape.

Reference numeral 110 denotes an elastic pressure roller which forms a fixing nip portion N having a predetermined width with a predetermined pressing force on the lower surface of the film guide member 111 with the fixing film 109 interposed therebetween, and mutually pressed.

The pressure roller 110 is driven to rotate counterclockwise as indicated by the arrow. A rotational force acts on the fixing film 109 by the frictional force between the pressure roller 110 and the outer surface of the fixing film 109 due to the rotational driving of the pressure roller 110. Then, the fixing film 109 slides while its inner surface is in close contact with the lower surface of the film guide member 111 at the fixing nip portion N, and the peripheral speed substantially corresponds to the rotational peripheral speed of the pressure roller 110 in the clockwise direction indicated by the arrow. With this, the outer periphery of the film guide member 111 is driven to rotate (pressure roller driving method).

The film guide member 111 presses the fixing nip N, supports the exciting coil 112 as a magnetic field generating means and the magnetic cores (core materials) 113a and 113b,
It serves to support 9 and improve the transport stability of the fixing film 109 during rotation. The film guide member 111 is an insulating member that does not hinder the passage of magnetic flux, and is made of a material that can withstand a high load.

The temperature of the fixing nip N is determined by the fixing film 10
The temperature is detected by temperature detecting means 118 abutting on the inner surface of 9 and the temperature is controlled so that a predetermined temperature is maintained by controlling the current supply to exciting coil 112 based on this.

In this manner, the pressure roller 110 is driven to rotate, and the cylindrical fixing film 109 rotates around the film guide member 111 in accordance therewith, and the power supply from the excitation circuit to the excitation coil 112 causes the electromagnetic force of the fixing film 109 to be reduced. Induction heat is generated.

When the temperature of the fixing nip N is raised to a predetermined temperature and the temperature is adjusted, the recording material P on which the unfixed toner image t is formed by the image forming means (not shown) is transferred to the fixing film of the fixing nip N. Introduced with the image surface facing upward, i.e., facing the fixing film surface, between the pressure roller 109 and the pressure roller 110, the image surface is sandwiched in a state of being in close contact with the outer surface of the fixing film 109, and together with the fixing film 109. The sheet is transported in the fixing nip portion N.

In the course of being conveyed through the fixing nip N, the unfixed toner image t on the recording material P is heated and fixed by heating by the electromagnetic induction heat of the fixing film 109.

When the recording material P passes through the fixing nip portion N, the recording material P separates from the outer surface of the rotary fixing film 109 to form an image T.
It is discharged and conveyed.

[0029]

However, there are the following problems in the electromagnetic induction type fixing device in which the fixing film 109 generates heat as shown in FIG.

When an attempt is made to increase the pressing force in order to further improve the permeability of the OHT and the fixing property of the thick paper, or when an attempt is made to increase the pressing force in order to increase the process speed of fixing the OHT or the thick paper. However, an increase in the rotational torque has caused a need to increase the output of the drive motor, which has caused a cost increase.

The lower surface of the sliding member 116 disposed on the lower surface of the film guide member 111 and the upper surface of the pressure roller 110 are pressed against each other with the fixing film 109 interposed therebetween.
Is formed.

For this reason, the fixing film 109 is deformed according to the shapes of the film guide member 111 and the sliding member 116. Along with this, the recording material P also followed this deformation, causing significant curl.

Further, as the number of prints increases, the film 109 is repeatedly deformed every time it passes through the fixing nip portion N. As a result, a problem such as cracking or breakage due to fatigue occurs.

Therefore, in the present invention, it is possible to minimize the deformation of the film in the fixing nip portion of the heating device of the electromagnetic induction heating system, to reduce the curl and the fatigue due to the repeated deformation of the film due to the durability. Aim.

[0035]

In order to achieve the above object, a typical configuration of the present invention is a film-like moving body, a guide member for guiding the moving body, and the moving body with respect to the guide member. A pressurizing member that forms a nip portion by pressure contact with the heating member, and a heating unit that heats the recording medium conveyed in the nip portion while moving the moving body by heating the moving body. In the above, the nip portion of the guide member, with which the pressing member is pressed through the moving body, has a continuous curvature convex in the direction of the pressing member.

According to the above configuration, the deformation of the moving body is reduced at the curvature portion, and the curl amount of the recording material can be reduced.
The life of the moving body can be extended.

Further, the contact area of the entire fixing nip portion is reduced, and the linear pressure is increased without increasing the total pressing force, thereby improving the fixing property and the transparency of the recording material. It becomes possible.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment of an image forming apparatus provided with a heating device according to the present invention will be described in detail with reference to the drawings. As for the order of the description, the image forming apparatus will be described first, and then the fixing device as the heating device will be described.

FIG. 2 is a schematic sectional view of an image forming apparatus using an electrophotographic process.

The image forming apparatus shown in FIG. 2 uses an intermediate transfer belt 6 as an intermediate transfer member, and a developing device 2, an exposure means 5 (hereinafter, referred to as a "laser scanner"), and an image carrier 1 (hereinafter, referred to as "a laser scanner") for each color. A photosensitive drum ”), a charging roller 3 and a cleaning unit 4 are collectively referred to as an image forming unit that forms a toner image on the recording material P.

The first photosensitive drum 1a in FIG.
The laser beam is uniformly charged by the charging roller 3a while being driven to rotate at a predetermined peripheral speed in the direction of 1, and is modulated by a laser beam modulated according to a digital image signal scanned by the laser scanner 5a. The electrostatic latent image of the first color (here, yellow) component is formed by receiving the image via the first color.

Subsequently, the electrostatic latent image is developed with the first color (yellow) toner using the first developing device 2a, and the first latent image is developed.
Obtain a visible image for the color components. The procedure described above is the second
This is performed for the color (magenta), the third color (cyan), and the fourth color (black).

In the first embodiment, the intermediate transfer belt 6 is driven to rotate at the same peripheral speed as the photosensitive drum 1a in the direction of arrow d2.

The transfer of the yellow visible image from the photosensitive drum 1a to the intermediate transfer belt 6 (primary transfer) is performed by applying a primary transfer bias supplied from a power source S1.

For magenta, cyan, and black, the same means is used to successively superimpose on the intermediate transfer belt 6 and perform primary transfer to obtain a superimposed toner image.

The toner image formed on the intermediate transfer belt 6 is collectively transferred (secondarily transferred) onto the recording material P conveyed at a nip portion with the secondary transfer roller 7.

The recording material P on which the toner image has been secondarily transferred is conveyed to a fixing device 8, where the toner image is fixed by heat and pressure at a fixing nip N between a fixing roller and a pressure roller.

Next, the fixing device 8 will be described in detail.

FIG. 1 is a cross-sectional view of the fixing device 8 according to the first embodiment. FIG. 3 is a front view of the fixing device 8 according to the first embodiment. FIG. 4 is a longitudinal sectional view of the fixing device 8 according to the first embodiment.

The fixing device 8 according to the first embodiment uses a cylindrical electromagnetic induction heat generating film as a moving body, employs a pressure roller driving method, and is applicable to an A3-size recording material P. In heating the fixing film 9, an electromagnetic induction heating method using an exciting coil 12 as a heating unit is adopted, and the fixing film 9 generates heat by generating an induced current in the fixing film 9.

The length Lf of the fixing film 9 shown in FIG. 3 in the longitudinal direction (the direction intersecting the transport direction of the recording material) is 350.
mm, and the longitudinal length Lr of the pressure roller 10 is 310
mm.

The magnetic cores 13a and 13b are members having high magnetic permeability, and are preferably made of a material used for a transformer core such as ferrite or permalloy, and more preferably 100 kHz.
Even above, it is preferable to use ferrite having a small loss. In the first embodiment, ferrite is used.

The exciting coil 12 has feeders 23a and 23b as shown in FIG.
The excitation circuit 24 shown in FIG. This excitation circuit 24 is 2
A high frequency of 0 kHz to 500 kHz can be generated by a switching power supply.

The exciting coil 12 generates an alternating magnetic flux by an alternating current (high-frequency current) supplied from the exciting circuit 24.

As shown in FIGS. 1, 3 and 4, a semicircular gutter type film guide member 11 as a guide member for guiding the fixing film 9 as a moving body is shown in FIG. The fixing film 9 which is a cylindrical electromagnetic induction heating film is loosely fitted on the outside of the fixing film 9.

The material of the film guide member 11 is excellent in insulation to secure insulation from the fixing film 9,
Good heat resistance is preferred. For example, a phenol resin, a fluorine resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, a PPS resin, a PFA resin, a PTFE resin, a FEP resin, an LCP resin, or the like may be selected.

The film guide member 11 holds the magnetic cores 13a and 13b as the magnetic field generating means and the exciting coil 12 inside.

Reference numeral 14 denotes a horizontally long pressing rigid stay disposed in contact with the flat surface of the inner surface of the film guide member 11.

Reference numeral 15 denotes a heat insulating member for preventing the heat of the fixing nip N from escaping to the rigid pressurizing stay 14.

Reference numeral 19 denotes the magnetic cores 13a and 13b and the exciting coil 12
It is an insulating member for insulating between the pressure stay 14 and the rigid stay 14 for pressure.

Reference numerals 21a and 21b denote flange members which are fitted to the left and right ends of the assembly of the film guide member 11, are rotatably mounted while fixing the left and right ends, and regulate and hold the ends of the fixing film 9. .

The pressing roller 10 as a pressing member includes a core 10
a, and a heat-resistant and elastic material layer 10b of silicon rubber, fluoro rubber, fluoro resin, or the like, formed and coated concentrically around the core 10a in a roller shape. It is arranged so as to be rotatably held between the chassis side plates (not shown) of the apparatus.

Pressing springs 22a and 22b are respectively contracted between both ends of the pressing rigid stay 14 and the spring receiving members 20a and 20b on the apparatus chassis side to apply a pressing force to the pressing rigid stay 14. ing. Thus, the film guide member 11 is pressed against the pressure roller 10 with the fixing film 9 interposed therebetween, and the fixing nip portion N is formed. In the film guide member 11, a sliding member 16 is disposed at a position facing the pressure roller 10.

As shown in FIG. 1, the pressure roller 10 is driven to rotate counterclockwise as indicated by the arrow. A rotational force acts on the fixing film 9 by the frictional force between the pressing roller 10 and the outer surface of the fixing film 9 due to the rotational driving of the pressing roller 10, and the fixing film 9 slides on the inner surface thereof at the fixing nip portion N. Member 16
The outer periphery of the film guide member 11 is rotated in a clockwise direction as indicated by an arrow with a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 10 while sliding in close contact with the lower surface of the film guide member 11.

In this case, in order to reduce the mutual sliding friction force between the lower surface of the sliding member 16 in the fixing nip N and the inner surface of the fixing film 9, the lower surface of the sliding member 16 in the fixing nip N and the fixing film 9 are fixed. A lubricant such as heat-resistant grease may be interposed between the sliding member 16 and the inner surface of the sliding member 16, or the lower surface of the sliding member 16 may be covered with a lubricating member.

FIG. 5 schematically shows the state of the alternating magnetic flux from the exciting coil 12 as the magnetic field generating means and the magnetic cores 13a and 13b. The magnetic flux M represents a part of the generated alternating magnetic flux.

The magnetic flux M guided to the magnetic cores 13a and 13b is
An eddy current is generated in the electromagnetic induction heating layer 9a of the fixing film 9. This eddy current generates Joule heat (eddy current loss) in the heat generating layer 9a due to the specific resistance of the heat generating layer 9a.

The exciting coil 12 is a copper wire (electric wire) constituting a coil (wire loop), which is a bundle of a plurality of thin wires made of insulated copper, each of which is a bundle (bundled wire). It is wound to form an exciting coil. In the present embodiment, the exciting coil 12 is formed by winding seven turns.

As the insulating coating, a coating having heat resistance is preferably used in consideration of heat conduction due to heat generation of the fixing film 9.
In this embodiment, a coating with polyimide is used, and the heat-resistant temperature is 220 ° C.

Here, the density may be improved by applying pressure from the outside of the exciting coil 12.

The shape of the exciting coil 12 conforms to the surface of the heat generating layer as shown in FIGS.

FIG. 6 is a cross-sectional view of the fixing film 9, and FIG. 6A is a cross-sectional view of the fixing film 9 in the first embodiment.

The fixing film 9 according to the first embodiment includes a heat generating layer 9a made of a metal film or the like serving as a base layer of the fixing film 9 having electromagnetic induction heat, and an elastic layer 9b laminated on the outer surface thereof.
And a composite structure of a release layer 9c laminated on the outer surface thereof.

For adhesion between the heat generating layer 9a and the elastic layer 9b and between the elastic layer 9b and the release layer 9c, a primer layer (not shown) may be provided between each layer.

In the above layer structure, the heat generating layer 9a is on the inner surface side of the cylindrical fixing film 9, and the release layer 9c is on the outer surface side.

As described above, the alternating magnetic flux acts on the heat generating layer 9a, so that an eddy current is generated in the heat generating layer 9a and the heat generating layer 9a
Generates heat. The heat heats the fixing film 9 via the elastic layer 9b and the release layer 9c, and heats the recording material P passing through the fixing nip portion N to heat and fix the toner image.

The heating layer 9 constituting the fixing film 9 will be described below.
a, the elastic layer 9b, and the release layer 9c will be described.

A) Heating Layer 9a The heating layer 9a may be made of a nonmagnetic metal, but is preferably made of a ferromagnetic metal such as nickel, aluminum nitride, ferromagnetic SUS, or a nickel-cobalt alloy.

It is preferable that the thickness is larger than the skin depth represented by the following formula and 200 μm or less. The skin depth σ [m] is expressed as σ = 503 × (ρ / fμ) 1/2 with the frequency f [Hz], the magnetic permeability μ, and the specific resistance ρ [Ωm] of the excitation circuit 24.

This indicates the depth of absorption of electromagnetic waves used in electromagnetic induction. At a depth deeper than this, the intensity of the electromagnetic waves becomes 1 / e or less, and conversely, most energy is absorbed up to this depth. Have been.

The thickness of the heat generating layer 9a is preferably 1 to 100.
μm is good. If the thickness of the heat generating layer 9a is smaller than 1 μm, most of the electromagnetic energy cannot be absorbed, and the efficiency becomes poor. On the other hand, if the heat generating layer exceeds 100 μm, the rigidity becomes too high, and the flexibility deteriorates, so that it is not practical to use as a rotation. Therefore, the thickness of the heat generating layer 9a is preferably 1 to 100 μm.

In the first embodiment, the heat generating layer 9a has a thickness of 50 μm.
Nickel.

B) Elastic Layer 9b The elastic layer 9b is made of silicon rubber, fluorine rubber, fluorosilicone rubber, or the like, and has good heat resistance and good thermal conductivity.

The thickness of the elastic layer 9b is preferably from 10 to 500 μm. The elastic layer 9b has a thickness necessary to guarantee the quality of a fixed image.

In printing an image, especially a photographic image, a solid image is formed over a large area on the recording material P. In this case, if the heating surface (the release layer 9c) cannot follow the unevenness of the recording material P or the unevenness of the toner layer, uneven heating will occur, and uneven gloss will occur on the image in the portion where the heat transfer amount is large and the portion where the heat transfer amount is small. In addition, the glossiness is high in a portion having a large heat transfer amount, and low in a portion having a small heat transfer amount. When the thickness of the elastic layer 9b is 10 μm or less, the elastic layer 9b cannot follow the unevenness of the recording material P or the toner layer, resulting in image gloss unevenness. If the thickness of the elastic layer 9b is 1000 μm or more, the thermal resistance of the elastic layer becomes large and it is difficult to realize a quick start. More preferably, the thickness of the elastic layer 9b is 5
It is preferably from 0 to 500 μm.

If the hardness of the elastic layer 9b is too high, the elasticity of the elastic layer 9b cannot follow the irregularities of the recording material P or the toner layer, resulting in uneven image gloss. Therefore, the hardness of the elastic layer 9b is not more than 60 ° (JIS-A), more preferably 45 ° (J
IS-A) The following is preferred.

The thermal conductivity λ of the elastic layer 9b is set to 0.1.
It is preferably from 25 to 0.84 [w · m ⁻¹ · K ⁻¹ ].

The thermal conductivity λ is 0.25 [w · m ⁻¹ · K ⁻¹ ]
If it is smaller, the thermal resistance is large, and the temperature rise in the surface layer (release layer 9c) of the fixing film 9 becomes slow.

The thermal conductivity λ is 0.84 [w · m ⁻¹ · K ⁻¹ ]
If it is larger than this, the hardness becomes too high or the compression set becomes worse.

Therefore, the thermal conductivity λ is 0.25 to 0.84
[W · m ⁻¹ · K ⁻¹ ] is preferable. More preferably 0.34 to
0.63 [w · m ⁻¹ · K ⁻¹ ] is preferable.

As described above, in the first embodiment, the elastic layer 9b is a silicon rubber having a thickness of 300 μm.

C) Release Layer 9c The release layer 9c is made of fluororesin, silicone resin, fluorosilicone rubber, fluororubber, silicon rubber, PFA resin,
A material having good releasability and heat resistance such as PTFE resin and FEP resin can be selected.

The thickness of the release layer 9c is preferably 1 to 100 μm. If the thickness of the release layer 9c is less than 1 μm, there will be problems such as uneven coating of the coating film, resulting in portions having poor release properties, and insufficient durability. The release layer is 100 μm
If the temperature exceeds the range, the heat conduction will be deteriorated. In particular, in the case of a resin-based release layer, the hardness becomes too high, and
The effect of b disappears.

In the first embodiment, the release layer 9c has a thickness of 5 μm.
PFA resin.

Although not particularly provided in the first embodiment, as shown in FIG. 6B, in the layer structure of the fixing film 9, the free surface side of the heat generating layer 9a (the elastic layer 9b side of the heat generating layer 9a is different from the elastic layer 9b side). A lubricating layer 9d may be provided on the opposite surface side).

The lubricating layer 9d is made of fluororesin, polyimide resin, polyamide resin, polyamideimide resin, P
EEK resin, PES resin, PPS resin, PFA resin, P
A heat-resistant resin such as TFE resin or FEP resin is preferable.

The lubricating layer 9d has a thickness of 10 to 1
000 μm is preferred. When the thickness of the lubricating layer 9d is smaller than 10 μm, no strength is obtained and the durability is insufficient. On the other hand, if it exceeds 1000 μm, the magnetic core 13a
The distance between the heating layer 9a and the excitation coil 13b increases, and the magnetic flux is not sufficiently absorbed by the heating layer 9a.

The lubricating layer may be a separate sleeve that fits inside the fixing film 9.

[0099] Due to the alternating magnetic flux generated by the alternating current, an eddy current generated in the electromagnetic induction heat generating film as the heat generating layer 9a causes the heat generation region H of the electromagnetic induction heat generating film as the heat generating layer 9a shown in FIG. I do.

The heat generated by the fixing film 9 is detected by the temperature detecting means 18.
By controlling the current supply to the exciting coil 12 by the temperature control system including the above, the temperature of the fixing nip portion N is controlled so as to be maintained at a predetermined temperature. The temperature detecting means 18 is a temperature sensor such as a thermistor for detecting the temperature of the fixing film 9. In the first embodiment, the temperature sensor 18 detects the temperature sensor 18 on the inner surface of the fixing film 9 downstream of the fixing nip portion N in the fixing film 9 rotation direction. And controls the temperature of the fixing nip N based on the temperature of the temperature sensor 18.

In the fixing operation, the pressure roller 10 is driven to rotate, and the cylindrical fixing film 9 rotates around the film guide member 11 accordingly. The fixing is performed in a state where the temperature of the fixing nip N is raised to a predetermined temperature of 180 ° C. and the temperature is controlled.

In the above state, the unfixed toner image t
Is introduced between the fixing film 9 and the pressure roller 10 in the fixing nip portion N, with the image surface facing upward, that is, facing the fixing film. In this process, the unfixed toner image t is heated and fixed on the recording material P by being heated by heat generated by electromagnetic induction of the fixing film 9 in this process.
After passing through the fixing nip N, the recording material P is separated from the outer surface of the rotary fixing film 9 and is discharged and conveyed. The heat-fixed toner image on the recording material P passes through the fixing nip N,
Upon cooling, a permanently fixed image T is formed.

In the first embodiment, since a toner containing a low softening substance is used in the unfixed toner image t, the fixing device 8 is not provided with an oil application mechanism for preventing offset. When a toner not used is used, an oil application mechanism may be provided. Also, when a toner containing a low softening substance is used, oil application or cooling separation may be performed.

At the time of the fixing operation in the conventional fixing device, in particular, when the recording material is an OHP film or a thick paper, in order to improve the transparency of an image, a method of decreasing the throughput or increasing the total pressing force is used. If not, good fixability and transmittance could not be satisfied.

Further, the deformation each time the fixing film 9 passes through the fixing nip portion N causes the recording material P to be curled, and it is necessary to newly provide a member for correcting the curl.

Therefore, in the first embodiment, in order to solve the above-mentioned problem, the amount of deformation of the fixing film 9 passing through the fixing nip portion N during the fixing operation can be reduced, the curl amount can be suppressed, and The film guide member 11 is configured as follows for the purpose of increasing the linear pressure without changing the total pressing force of the fixing nip portion N.

FIG. 7 is a perspective view of the sliding member according to the first embodiment.

As shown in FIG. 7, the film guide member 11
The sliding member 16 is disposed in a fixing nip portion N (a portion where the fixing roller 9 is pressed against the pressure roller 10 via the fixing film 9).
Has a curvature portion 17 having a continuous curvature convex in the direction of the pressure roller 10.

The curvature of the curvature portion 17 is preferably 0.8R to 3.0R, where R is the curvature of the film guide member 11. In the first embodiment, the curvature of the curvature portion 17 of the sliding member 16 is 2.2R when the curvature of the film guide member 11 is R, but the present invention is not limited to this.

In the first embodiment, the film guide member 11
PPS resin or LCP resin for the sliding member 16
By using polyimide resin or PEEK resin, the film guide member 11 was made more slidable.

As described above, in the first embodiment, as shown in FIG. 7, the sliding member 16 disposed in the fixing nip portion N of the film guide member 11 has a continuous curvature ( By providing the curvature portion 17), the deformation of the fixing film 9 can be reduced, and accordingly, the recording material P
The curl amount can be suppressed, and the fixing property and the transparency can be improved even for a recording material or the like that requires the transparency.

Further, since the fixing film 9 does not repeatedly deform at the fixing nip portion N, the fatigue of the fixing film 9 is reduced, and as a result, the life of the fixing film 9 can be extended.

Further, since the process speed is not changed by the recording material P, the throughput can be improved.

Here, a sliding member having a curvature portion 17 is used here.
16, the case where the film guide member 11 is configured from a member different from the example, but the present invention is not limited thereto,
At the pressure contact portion with the pressure roller 10 via the fixing film 9, the film guide member 11 itself may be configured to have a continuous curvature convex in the direction of the pressure roller 10. Regarding this configuration, the same can be said for the second embodiment and the third embodiment.

(Second Embodiment) FIG. 8 is a perspective view of a sliding member 16 according to a second embodiment.

In the present embodiment, as shown in the figure, a plurality of crown-shaped concave portions 30 are arranged on the surface of the sliding member 16 in a grid pattern with respect to the moving direction of the fixing film 9 shown in FIG. .

The spherical crown-shaped concave portion 30 can hold a lubricant such as grease between the fixing film 9 and the fixing film 9 at the fixing nip portion N in FIG. It can be achieved at the same time. In the present embodiment, the diameter of the spherical crown-shaped recess is 2.5 mm and the depth is 0.2 mm.

(Third Embodiment) FIG. 9 is a perspective view of a sliding member 16 according to a third embodiment.

In this embodiment, a plurality of grooves 31 are arranged on the surface of the sliding member 16 at an angle to the moving direction of the fixing film 9 in FIG. 1, as shown in FIG.

The groove 31 makes it possible to hold a lubricant such as grease between the fixing film 9 and the fixing film 9 at the fixing nip N in FIG. 1 for a long time.
An improvement in slidability can also be expected. In this embodiment, the fixing film 9 is formed by grooves 31 having a width of 5 mm and a depth of 0.2 mm at intervals of 20 mm crossing the moving direction of the fixing film 9 obliquely.

Further, as a development example of this embodiment, the interval and angle of the grooves are set so that the number of the grooves 31 in an arbitrary cross section perpendicular to the longitudinal direction of the sliding member 16 is the same. A uniform temperature distribution can be achieved, and the lubricant can be uniformly held between the fixing film 9 and the surface of the film guide member 11 in FIG. 1, which is advantageous for sliding resistance. .

(Other Embodiment) FIG. 10 shows the configuration of another embodiment of the fixing device.

FIGS. 10 (a), (b) and (c) show other embodiments of the fixing device of the electromagnetic induction heating type, respectively.
FIG. 10D shows an embodiment of a heating type fixing device using a resistance heating element.

The fixing device shown in FIG. 10A has an endless belt-like shape between the lower surface of the sliding member 16 of the electromagnetic induction heating structure 217, the driving roller 225, and the driven roller (tension roller) 226. In this configuration, the film 230 as a conductive member is stretched around and the film 230 is rotationally driven by the driving roller 225. Reference numeral 210 denotes a pressure roller which is pressed against the lower surface of the sliding member with the film 230 interposed therebetween, and is driven to rotate as the film 230 rotates.

The fixing device shown in FIG. 10B is composed of a lower surface of the sliding member 16 of the electromagnetic induction heating structure 217 and a driving roller 225.
In this configuration, a film 230 as an endless belt-shaped conductive member is suspended between the members, and is driven to rotate by a driving roller 225.

The fixing device shown in FIG. 10C uses, instead of the endless belt-shaped film, a long endless film 231 wound in a roll, as the film 230 as a conductive member, and feeds the film from the feeding shaft 227 side. Electromagnetic induction heating structure 217
This is configured to travel at a predetermined speed toward the winding shaft 228 via the lower surface of the sliding member 16.

In the fixing device shown in FIG. 10D, an endless film 230 is externally fitted to a sliding member 16 holding a linear resistance heating element 240 elongated in the film width direction, and the film 230 is slid. The pressure roller 210 is pressed against the lower surface of the moving member 16, and the film 230 is rotationally driven by driving the pressure roller 210.

Even when the sliding member 16 of the first to third embodiments is applied to the above four fixing devices, the same effect as that of the above embodiment can be obtained.

[0129]

As described above, according to the present invention, the nip portion of the guide member, to which the pressing member presses through the moving body, has a continuous curvature convex in the direction of the pressing member. As a result, the amount of deformation of the moving body can be reduced, and accordingly, the amount of deformation of the recording material can be reduced, without increasing the pressing force or reducing the throughput at the same time. It is possible to provide a heating device and an image forming apparatus that can achieve an improvement in fixing property and an improvement in transmissivity, and can further extend the life of a moving body.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fixing device according to a first embodiment.

FIG. 2 is a schematic cross-sectional view of an image forming apparatus using an electrophotographic process.

FIG. 3 is a front view of the fixing device according to the first embodiment.

FIG. 4 is a longitudinal sectional view of the fixing device according to the first embodiment.

FIG. 5 is an explanatory diagram of a state of an alternating magnetic flux from an exciting coil and a magnetic core.

FIG. 6 is a sectional view of a fixing film.

FIG. 7 is a perspective view of a sliding member according to the first embodiment.

FIG. 8 is a perspective view of a sliding member according to a second embodiment.

FIG. 9 is a perspective view of a sliding member according to a third embodiment.

FIG. 10 is a diagram illustrating a configuration of another embodiment of a fixing device.

FIG. 11 is a diagram illustrating a configuration of a conventional electromagnetic induction heating type fixing device.

[Explanation of symbols]

 H: Heat generation area M: Magnetic flux N: Fixing nip P: Recording material T: Permanently fixed image t: Unfixed toner image 2: Developing device 3: Charging roller 4 ... Cleaning means 5 ... Exposure means 6 ... 7 ... 2 Next transfer roller 8 ... Fixing device 9 ... Fixing film 9a ... Heat generating layer 9b ... Elastic layer 9c ... Release layer 9d ... Lubricating layer 10 ... Pressure roller 10a ... Core metal 10b ... Elastic material layer 11 ... Film guide member 12 ... Excitation Coil 13a, 13b ... Magnetic core 14 ... Rigid stay for pressing 15 ... Heat insulating member 16 ... Sliding member 17 ... Curvature section 18 ... Temperature detecting means 19 ... Insulating member 20a, 20b ... Spring receiving member 22a, 22b ... Pressing spring 21a, 21b: Flange members 23a, 23b: Power supply unit 24: Excitation circuit 30: Recess 31: Groove 210: Pressure roller 217: Electromagnetic induction heating structure 225: Driving roller 227: Shaft 228: Shaft 230: Film 240: Wire Resistance heating element

Continued on the front page F-term (reference) 2H033 AA15 AA23 AA47 BA11 BA12 BA25 BA27 BB28 BB33 BE03 BE06 3K059 AA08 AB04 CD52 CD75

Claims (10)

[Claims] 1. A moving member in the form of a film, a guide member for guiding the moving member, a pressing member for pressing the guide member through the moving member to form a nip portion, A heating means for heating the recording material conveyed in the nip portion with the movement of the moving body while moving the moving body, wherein the pressing member presses the guide member via the moving body. The heating device, wherein the nip portion has a continuous curvature convex in the direction of the pressing member. 2. When the curvature of the guide member is R,
The heating device according to claim 1, wherein the curvature of the curvature portion of the guide member is 0.8R to 3.0R. 3. The heating device according to claim 1, wherein the curvature portion of the guide member is formed of a member different from the guide member. 4. The heating device according to claim 1, wherein a plurality of spherical crown-shaped concave portions are provided in the curvature portion of the guide member. 5. The heating device according to claim 1, wherein a plurality of grooves are disposed in the curvature portion of the guide member at an angle to the moving direction of the moving body. apparatus. 6. The curved portion of the guide member, wherein the plurality of grooves have the same number of grooves in an arbitrary cross section perpendicular to the longitudinal direction of the guide member. Heating equipment. 7. The heating device according to claim 1, wherein the heating means generates heat by causing the moving body to generate an induced current. 8. The heating apparatus according to claim 1, wherein the heating means has a lubricant interposed between the moving body and the guide member. 9. The heating apparatus according to claim 1, wherein an image formed on the recording material is subjected to a heating process. 10. The image forming means for forming a toner image on a recording material, and the heating device according to claim 1, wherein the heating device heats the toner image on the recording material. An image forming apparatus comprising: