JP2962859B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device which is used in an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus and heats and fixes a visible image on a recording material. In particular, the present invention relates to a fixing device that heats and fixes a visible image via a thin film.

[0002]

2. Description of the Related Art Conventionally, as a heat fixing apparatus, a recording material is held and conveyed by a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and pressing against the heating roller. Heat roller systems for heating are often used.

However, since the heating roller requires a large heat capacity to prevent temperature fluctuation, a long wait time, which is an image formation inhibition time from when the main switch is turned on to when a predetermined temperature is reached, is required.

Therefore, the applicant has disclosed Japanese Patent Application Laid-Open No. 63-31818.
No. 2, Japanese Patent Application No. 2-153602-153610, etc., have previously proposed a heater having a small heat capacity which instantaneously raises the temperature, and a fixing device which uses a thin film to greatly reduce or reduce the wait time.

[0005]

However, in such a fixing device using a heater and a film that generates heat toward the nip portion, the temperature of the contact surface with the toner cannot be controlled. The variation in temperature increases.

For this reason, there is not much problem because the temperature region where offset does not occur is wide in single color printing, but there is not much problem. However, in the case of fixing a full-color image in which mixed toners are mixed, offset occurs because the temperature latitude at which offset does not occur is narrow. Easy to do.

In the case of the heat roller fixing method, heating from the pressure roller side can be considered. However, if the amount of heat applied to the color toner changes, the color and gloss change.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a heating element having a heating resistor, and a recording apparatus in which one surface slides with the heating element while the other surface carries an unfixed image. A film that contacts and moves together with the material, a pressing rotator that forms a nip with the heating element through the film, a first temperature detection member that detects the temperature of the heating element, and a first temperature detection during fixing. And a first energization control unit that controls energization of the heating resistor so that a detected temperature of the member is constant, and an image forming apparatus that starts image formation on a recording material by inputting an image formation start signal A heater for heating the pressing rotator from inside the pressing rotator, a second temperature detecting member for detecting a surface temperature of the pressing rotator, and a second The heater is controlled so that the temperature detected by the temperature detection member is constant. A second power supply control means for controlling power supply, wherein the first power supply control means and the second power supply control means start power supply at a predetermined timing in response to input of an image formation start signal to the image forming apparatus. It is characterized by doing.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a sectional view of an image forming apparatus using a fixing device according to an embodiment of the present invention.

The image forming apparatus of this embodiment is an electrophotographic color image forming apparatus of a document image photoelectric reading type, laser beam scanning exposure type and multiple transfer type.

Reference numeral 30 denotes an image forming apparatus main body, and reference numeral 50 denotes an original image photoelectric reading device (scanner) mounted thereon. The original image photoelectric reading device 50 reads the color component pattern of the image of the original 0 placed and set on the original table glass 51 by one or more scanning movement operations of the photoelectric reading unit 52. Thereby, a yellow image signal, a magenta image signal, a cyan image signal,
A black image signal is input.

In the main body 30 of the image forming apparatus, reference numeral 31 denotes an electrophotographic photosensitive drum (hereinafter, referred to as a drum) as an image carrier, which is driven to rotate at a predetermined peripheral speed (process speed) in a counterclockwise direction indicated by an arrow. Is done. A primary charger 32 uniformly charges the drum 1 to a predetermined polarity and potential.
3 is a laser beam L modulated by an image signal from the control circuit
Is a laser beam scanner that scans and exposes the charged rotary drum 31 by scanning. An electrostatic latent image corresponding to an image signal is formed on the surface of the drum 31 by the scanning exposure.

Reference numeral 34 denotes a rotary developing device which includes a yellow developing device 34Y, a magenta developing device 34M, and a cyan developing device 34.
C, a black developing unit 34BK, and each of the above-mentioned developing units is connected to a drum 31 by a color switching signal.
Are sequentially switched in a rotary manner to the action position with respect to.
Then, the formed latent image on the surface of the drum 31 is developed with the toner of the developing device which is switched to the drum 31 at a predetermined position.

Reference numeral 35 denotes a transfer drum, and the photosensitive drum 31
The drum 31 is driven to rotate in the forward direction at substantially the same peripheral speed as the rotation of the drum 31. The transfer material P as a recording material is fed one by one to the transfer drum 35 from the first or second paper feed cassette 36 or 37 by driving the paper feed roller 36a or 37a. , And the leading end of the transfer material is sandwiched by a cooperating gripper 41 of the transfer drum 35 and the transfer material contact roller 40, so that the transfer material is wrapped around the outer peripheral surface of the transfer drum 35. Then, the formed toner image on the drum 31 side is transferred by the transfer charger 42 to the wrapped transfer material surface. Transfer drum 3
The transfer material wound and held around 5 receives the toner image transfer repeatedly a predetermined number of times. 43 is a drum 1 after transfer
A static eliminator 44 for eliminating the surface is a cleaning device for cleaning the surface of the drum 31.

In the case of this embodiment, when forming a full-color image, charging → exposure L by yellow image signal → development by yellow developing unit 34Y → transfer → discharge → cleaning charging → exposure by magenta image signal → developing by magenta developing unit 34M → Transfer → Electrification → Cleaning Charge → Cyan image signal exposure L → Cyan developing device 3
4C development → transfer → charge removal → cleaning electrification → exposure using black image signal → development by black developing unit 34BK → transfer → charge removal → cleaning By sequentially transferring the magenta toner image, the cyan toner image, and the black toner image to the same transfer material held on the transfer drum 35, a full-color image is formed on the transfer material surface.

When the transfer of the final black toner image is started, the gripping of the tip of the transfer material by the clipper 41 is released, and the transfer material is separated from the transfer drum 35 by the charge / separation charger 45 / separation claw 46. The sheet is conveyed to the fixing device 11 by the conveying belt 47, is subjected to the mixed-color fixing process, and is discharged to the discharge tray 48.

Next, the toner used in the image forming apparatus will be described.

In the formation of a color image or a full-color image, by using a sharp-melt toner, the color reproduction range of a copy can be widened and a color copy faithful to a multicolor or full-color image of an original can be obtained. .

The toner is produced by melt-kneading, pulverizing, and classifying a binder resin such as a polyester resin or a styrene-acryl ester resin, a colorant (dye, a sublimable dye), and a toner-forming material such as a charge control agent. Is done. If necessary, an external addition step of adding various external additives (for example, hydrophobic colloidal silica) to the toner may be added.

In consideration of the fixability and the sharp melt property, the color toner particularly preferably uses a polyester resin as the binder resin. Examples of the sharp melt polyester resin include a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid.

In particular, the following equation

[0023]

[Outside 1] (Wherein R is an ethylene or propylene group, x, y
Are each a positive integer of 1 or more, and the average value of x + y is 2 to 10), and a bisphenol dielectric represented by the formula or a substituted product thereof as a diol component, a divalent or higher carboxylic acid or an acid anhydride thereof. Or a polyester resin obtained by at least co-condensation polymerization with a carboxylic acid component (for example, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) comprising the lower alkyl ester. It is more preferable because it has melting characteristics.

The softening point of the polyester resin is 75 to 150.
° C, preferably 80 to 120 ° C. FIG. 5 shows the softening characteristics of a toner containing a polyester resin as a binder resin. The method for measuring the softening point in the present invention will be described below.

Using a flow tester CFT-500A type (manufactured by Shimadzu Corporation), die (nozzle) diameter 0.2 m
m, a thickness of 1.0 mm, an extrusion load of 20 kg, an initial set temperature of 70 ° C., a preheating time of 300 seconds, and a constant temperature increase at a rate of 6 ° C./min. A temperature curve (hereinafter referred to as a softening S-order curve) is obtained. The toner used as the sample is a fine powder precisely weighed from 1 to 3 g, and the cross-sectional area of the plunger is 1.0 cm ² . Softening S
The character curve becomes a curve as shown in FIG. As the temperature rises at a constant speed, the toner is gradually heated and starts to flow (plunger descent A → B). When the temperature is further increased, the toner in the molten state flows out greatly (B → C → D), the plunger descent stops, and the process ends (D → E).

The height H of the S-shaped curve indicates the total outflow, and H /
The temperature T ₀ corresponding to the C point 2 indicates the softening point of the sample (for example, toner or resin).

Whether or not the toner and the binder resin have sharp melt properties can be determined by measuring the apparent melt viscosity of the toner or the binder resin.

In the present invention, the toner having a sharp melt property or the binder resin has an apparent melt viscosity of 10 ^3.
When the temperature at which shows the T _1, 5 × 10 ² poise temperature when showing the poise and _{T 2, T 1 = 90~150 ℃} | △ T | = | T 1 -T 2 | = 5~20 The one that satisfies the condition of ° C.

The sharp-melt resin having these temperature-melt viscosity characteristics is characterized in that the viscosity decreases sharply when heated. Such a decrease in viscosity causes appropriate mixing between the uppermost toner layer and the lowermost toner layer, and furthermore, the transparency of the toner layer itself is sharply increased, and good color reduction mixing is caused.

Such a sharp-melting color toner has a high affinity and is easily offset at the time of fixing.

Next, a fixing device according to an embodiment of the present invention will be described in detail.

FIG. 1 is a schematic diagram showing an example of a film heating type fixing device according to the present invention.

Reference numeral 11 denotes a general reference for the fixing device. 24
Is an endless belt-shaped heat-resistant fixing film,
The left driving roller 25, the right driven roller 26, and the low heat capacity linear heating element 20 as a heating element disposed below between the driving roller 25 and the driven roller 26, which are parallel to each other.
It is suspended between members 25, 26 and 20.

The driven roller 26 also serves as a tension roller for the endless belt-shaped fixing film 24.
The fixing film 24 serves as a recording material carrying an unfixed toner image Ta conveyed from an image forming unit (not shown) on the upper surface at a predetermined peripheral speed in the clockwise direction accompanying the clockwise rotation of the driving roller 25. At the same peripheral speed as the transfer speed of the transfer material sheet P (50 mm / sec in this example) without wrinkles, meandering, and speed delay.

Reference numeral 28 denotes a pressure roller having a rubber elastic layer of silicone rubber or the like having good releasability as a pressure member, and the heating element sandwiching the descending film portion of the endless belt-shaped fixing film 24. The transfer material sheet P is counter-pressed against the lower surface of the transfer member 20 by a biasing means (not shown) with a total pressure of, for example, 4 to 7 kg.

H denotes a halogen heater provided in the pressure roller 28, and 70 denotes a thermistor, which is elastically pressed against the surface of the pressure roller by an elastic sponge rubber 71 and a leaf spring 72.

At least at the time of fixing, the temperature control circuit 73 controls the energization of the halogen heater 70 by a drive circuit 74 such as a triac so that the detection output of the thermistor 70 becomes a predetermined value.

The pressing roller 28 of this embodiment is a core metal 28.
1 is a silicone rubber roller having an outer diameter of 30 mm formed by concentrically forming a 3 mm-thick silicone rubber on the outer periphery of the mold 1 by die molding or the like.

The heating element 20 is a low-heat-capacity linear heating element whose longitudinal direction extends in a direction (width direction of the film) that intersects the surface movement direction of the fixing film 24.
1, a heating resistor (heating element) 22, a temperature measuring element 23, etc., which are mounted and held on a heater support 27 and fixedly supported.

The heater support member 27 supports the heating member 20 insulatively with respect to the fixing device 11 and the entire image forming apparatus in which the fixing device is incorporated. For example, PPS (polyphenylene sulfide), PAI (polyamide imide), PI
Highly heat-resistant resins such as (polyimide), PEEK (polyetheretherketone), and liquid crystal polymer, and composite materials of these resins with ceramics, metals, glass, and the like.

The heater substrate 21 is a member having heat resistance, insulation, low heat capacity, and high heat conductivity.
It is an alumina substrate having a width of 10 mm and a length of 310 mm.

The heating element 22 is, for example, Ag / Pd (silver palladium), Ta, or the like along the length substantially at the center of the lower surface of the heater substrate 21 (facing the film 24).
₂ N, about 10 [mu] m · width 1 Thickness of electrically resistive material of RuO _2, etc.
〜3 mm is applied by screen printing or the like, and a heat-resistant resin such as heat-resistant glass or PTFE is coated thereon as a surface protection layer 21 a by about 10 μm.

As an example, the temperature detecting element 23 has a low heat capacity such as a Pt film or the like provided by applying a screen printing or the like to a substantially central portion of the upper surface of the substrate 21 (the surface opposite to the surface on which the heating element 22 is provided). Is a resistance thermometer. As the temperature detecting element, a configuration may be adopted in which a thermistor having a low heat capacity or the like is disposed in contact with the substrate 21.

In the case of the heating element 20 of the present embodiment, a current is applied to the linear or band-shaped resistance heating element 22 from both ends in the longitudinal direction, and the heating element 22 generates heat over substantially the entire length. Energization is performed at 100 V AC.
The temperature control circuit 73 controls the phase angle to be energized by the energization control circuit 75 including the triac so that the detected temperature of 3 becomes constant, thereby controlling the energized power and controlling the fixing temperature to 180 ° C. ing.

Next, the fixing film 2 used in this embodiment
4 will be described.

The fixing layer 24 has a total thickness of 100 μm in order to reduce the heat capacity and achieve quick start.
m or less, preferably 40 μm or less, a film having heat resistance, release property, durability and the like can be used. FIG. 2 is a schematic diagram of a layer structure of an example of a composite layer film as a whole film, and this example is a two-layer film. 24a is a heat-resistant layer as a base layer (base film) of the fixing film, and 24b is a release layer (surface layer) laminated on the outer surface of the heat-resistant layer 24a (the surface facing the toner surface image).

The heat-resistant layer 24a is made of a high heat-resistant resin film such as polyimide, polyetheretherketone (PEEK), polyethersulfone (PES), polyetherimide (PEI), polyparabanic acid (PPA), or the like.
Materials having excellent strength and heat resistance, such as metals such as Ni, SUS, and Al, can be used.

The release layer 24b can be made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene), PFA, or FEP if only the black toner image is fixed, but the color toner image is fixed without offset. Therefore, it is used as cone rubber for improving fixability.

The surface resistance of the release layer 24b may be reduced by a method such as mixing a conductive agent such as carbon black, graphite, or conductive whiskers. In this case, the charging of the toner contact surface of the fixing film 24 can be prevented. When the toner contact surface of the fixing film 24 is insulative, the surface of the fixing film is charged, disturbing the toner image on the sheet P or transferring the toner image to the fixing film 24 (so-called charging offset). In some cases, this problem can be solved by lowering the resistance of the release layer.

In particular, the surface resistance of the release layer 24b is set to 10 ¹⁰
It is preferably set to Ω or less.

The fixing film 24 is not limited to the two-layer structure as described above, and may have a multilayer structure of three or more layers including a silicone rubber layer at least on the surface in contact with the toner image. A silicone rubber single-layer film that has been strengthened by adding a filler or the like may be used.

In general, when fixing a color image, a fixed image having high glossiness is often required in terms of color reproducibility and appearance. The film heating method of the present invention is particularly effective for fixing such a color image requiring high image glossiness, and the surface of the fixing film 24 (the surface of the recording material which is in contact with the toner image should be formed with less roughness). It is also possible to obtain a low gloss image by roughening the surface of the fixing film 24.

After the fixing film is formed, the surface may be roughened by blast treatment or the like. To make the surface smooth, a fixing film may be prepared using a conventionally known inner mirror mold and a fixing film may be formed. It is possible by a method such as finishing the surface to have a high smoothness, but it is not particularly limited to this method.

Next, the operation of the present fixing device will be described.

An unfixed toner image (black toner image or full-color toner image) Ta conveyed from the image forming section (not shown) to the fixing device 11 is carried on the upper surface by the image forming operation of the apparatus in response to the image forming start signal. The transfer material sheet P as a recording material is guided by a guide 29 and enters between the fixing film 24 and the pressure roller 28 at a pressure contact portion N between the heating body 20 and the pressure roller 28, and the unfixed toner image surface And the heating element 20 and the pressure roller in a state of being overlapped with the fixing film 24 without causing surface deviation or wrinkling by closely contacting the lower surface of the fixing film 24 rotated in the same direction at the same speed as the conveying speed of the sheet P. 28 while receiving the pinching pressure.

The heating element 20 and the pressure roller 28 are energized and heated at a predetermined timing according to an image formation start signal, so that the toner image Ta is heated at the pressure contact portion N to become a softened and fused image Tb.

The traveling direction of the fixing film 24 turns at a sharp angle (bending angle θ is approximately 45 °) at the edge portion S (curvature radius is about 2 mm) of the heater support 27 where the curvature is large. Accordingly, the sheet P conveyed through the pressure contact portion N while overlapping the fixing film 24 is separated from the fixing film 24 at the edge portion S by a curvature, and at this separation, the toner image Ta is a full-color toner image. Even if there is, the toner offset is not substantially generated because the release layer 24a of the fixing film 24, which is the surface in contact with the toner image, is made of silicone rubber.

Sheet P separated from fixing film 24
Is discharged to the discharge tray 12. By the time the sheet 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 this embodiment, the heating element 22 of the heating element 20
In addition, since the heat capacity of the substrate 21 is small, and these are thermally insulated by the support body 27, the surface temperature of the heating body 20 at the press-contact portion N can be reduced in a short time to the melting point of the toner (or the fixing temperature to the sheet P) Since the temperature is raised to a sufficiently high temperature, it is not necessary to raise the temperature of the heating body 20 in advance (so-called standby temperature control), energy can be saved, and the temperature inside the apparatus can be prevented from rising.

Reference numeral 10 denotes a cleaning and applicator for cleaning the fixing film 24 and applying silicone oil.

No abutting member such as a thermistor or a separation claw is provided on the outer peripheral surface of the film in the direction perpendicular to the transport direction of the transfer material.

Therefore, even if a large amount of release oil is applied, uneven gloss due to a difference in the amount of applied oil does not occur.

The surface of the pressure roller is also kept at a constant temperature of 110 ° C.

Therefore, in the nip, the pressure roller surface is 18
Since the temperature is kept at 0 ° C., the nip temperature is kept constant even though the temperature of the fixing film is not controlled.

It should be noted that the pressure roller 2
The temperature rise of 8 is slow.

Therefore, in printing immediately after the main switch of the apparatus is turned on, the pressure roller is not sufficiently heated as a whole, but the pressure roller rotates before the recording material enters the fixing nip. When the surface is heated by the heating element 20, a sufficient fixing property is obtained.

Also, during continuous printing, in which temperature fluctuations are likely to occur, the pressure roller surface temperature is kept constant, so that the temperature of the heating element 20 is kept constant so that the film surface temperature in the nip does not fluctuate. .

FIG. 3 is a sectional view of a fixing device according to another embodiment of the present invention.

The fixing film 24 is not limited to the endless belt shape, and the endless fixing film 24 wound around the feed shaft 12 in the form of a roll as shown in FIG. (The film take-up type) in which the transfer material sheet P is moved from the delivery shaft 12 to the take-up shaft 13 at the same speed as the transfer speed of the transfer material sheet P.

Next, more specific experimental examples will be described.

[Experimental Example 1] The apparatus configuration shown in FIG. 1 was used.

An HTV silicone rubber layer having a JISA hardness of 40 ° and a thickness of 3 mm was provided as a pressing roller 28 on a cored bar.
This silicone rubber was coated with a 50 μm-thick fluororesin tube and had an outer diameter of 30 mm. A halogen heater of 300 W was built in and the detection temperature of the thermistor 70 was 1
It controlled so that it might be 10 ° C.

Further, as the endless fixing film 24, a two-layer composite film of the following heat-resistant layer (base layer, base film) 24a and release layer (surface layer) 24b was used. Heat-resistant layer 24a 20 μm thick polyimide film Release layer 24b 10 μm thick RTV (room temperature vulcanization type) silicone rubber layer It is manufactured by coating and spray coating RTV silicone rubber.

When the fixing device 11 was used in the image forming apparatus shown in FIG. 4 to perform a fixing process of a full-color image, a preferable and satisfactory fixing process without toner offset to the fixing film was performed.

Comparative Example 1 A full-color image fixing process was performed using the same apparatus as that of the above-described experimental example except that the pressure roller did not include a halogen heater.

The glossiness of the image became less than that of the thirtieth continuous paper passing, and a cold offset in which the toner peeled off from the transfer material occurred.

This is because, despite the fact that the temperature of the heating element is maintained at 180 ° C., the temperature of the pressure roller decreases with continuous paper passing, and the amount of heat applied to the toner at the nip decreases.

EXPERIMENTAL EXAMPLE 2 Using a black toner, a fixing film having a surface coated with PFA was used as the release layer 24b in the fixing device shown in FIG.

A film coated with PFA on the surface is used. The pressure roller is 28 mm in outer diameter and 3 mm in rubber thickness.
The surface temperature was adjusted to 110 ° C. using a heater having a built-in 100 W halogen heater in the mm heater.

As a result, when a fixing test was continuously performed on a black and white unfixed image, satisfactory fixing such as a line image and a solid image could be performed.

COMPARATIVE EXAMPLE 2 When a heater of 400 W was inserted into the pressure roller and heating was constantly performed to perform fixing, hot offset occurred from the 50th sheet of continuous fixing.

This is because the temperature of the pressure roller increases with continuous paper passing, and a very high amount of heat is applied to the toner despite the fact that the heating element is maintained at a constant temperature.

Experimental Example 3 The following two-layer composite film was used as the endless fixing film 24 in Experimental Example 1.

Heat resistant layer 24a 20 μm thick polyimide film Release layer 24b 50 μm thick LTV (low temperature vulcanization type)
Silicone rubber layer and release layer 24b as shown in FIG.
A felt pad 10 (trade name Nomex or the like) impregnated with silicone oil (dimethyl silicone oil 10,000 CS) was brought into contact with the surface of. Thereby, high releasability can be obtained by the silicone oil as the release agent applied from the pad 10 of the release layer 24b of the LTV silicone rubber. The release agent applying mechanism 10 may be a roller body, a web, or the like in which silicone oil is impregnated or applied.

As the pressure roller, a roller having an outer diameter of 30 mm and a rubber thickness of 2 mm was used, and a halogen heater of 200 W was built therein.

The halogen roller heats the pressure roller so as to keep it at 100 ° C.

Also in the case of this fixing device, favorable and favorable fixing processing without toner offset to the fixing film was carried out in color image fixing.

[Experimental Example 4] In the fixing device 11 shown in FIG. 1, a single-layer film of a 120 μm thick one-component RTV silicone rubber film was used as the endless fixing film 24. The strength of this film was increased by selecting and increasing the amount of conventionally known fillers and fillers.

Also in the case of this fixing device, favorable and favorable fixing processing without toner offset to the fixing film was carried out in color image fixing.

[Experimental Example 5] A color image was formed on the recording material P by using a transparency film for an overhead projector (hereinafter referred to as an OHP film) using the fixing device of the above-described execution example 2. And
The fixing of the color image was executed.

In the fixing of the OHP sheet, the fixing speed was reduced to half of that for paper (that is, 25 mm / sec in the present embodiment) in order to require toner permeability. In this case, since the heating amount in the heating unit N is doubled, the degree of softening of the toner is increased, and the toner is also softened in the edge part S. That a fixing film is used and that a moderately constant heating is applied from the pressure roller side,
In addition to the application of oil, it is possible to perform fixing on an OHP sheet from which no offset occurs and high transparency can be obtained.

With this configuration, even if the heating / cooling state changes depending on the type of transfer material such as thin paper, the offset to the fixing film which occurs when the toner is not completely cooled is generated. Phenomena did not occur, and good fixing could be performed.

Further, although the cleaning means of the fixing film is not particularly illustrated in each of the execution examples, when the oil applying means 10 is a felt or a web, it simultaneously serves as the cleaning means. Cleaning means may be provided separately from the oil applying means 10.

The rubber thickness and the material of the pressure roller are preferably high in heat resistance because they have a heater inside, and the thickness is preferably as thin as 3 mm or less.

[0095]

As described above, according to the present invention, the fluctuation of the amount of heat applied to the toner at the nip can be reduced without controlling the temperature of the film in contact with the toner.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a fixing device according to the present invention.

FIG. 2 is a schematic cross-sectional view of a layer structure of a fixing film.

FIG. 3 is a schematic configuration diagram of another configuration example of the fixing device.

FIG. 4 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 5 is a flow tester diagram of the toner.

[Explanation of symbols]

 Reference Signs List 20 heating element 24 fixing film 24a heat-resistant layer (base film) 24b release layer (surface layer) 28 pressure roller 10 silicone oil impregnated felt 70 thermistor H heater P recording material

Claims (1)

(57) [Claims] 1. A heating element having a heating resistor, a film having one surface sliding with the heating element and the other surface moving in contact with a recording material bearing an unfixed image, and A pressure rotating body that forms a nip with the heating body, a first temperature detection member that detects the temperature of the heating body,
A first energization control means for controlling energization to the heating resistor so that the detection temperature of the temperature detection member is constant,
In a fixing device used in an image forming apparatus which starts image formation on a recording material by input of an image formation start signal, a heater for heating a pressing rotator from inside the pressing rotator; A second temperature detecting member for detecting a surface temperature, and a second energizing control means for controlling energization to the heater so that a detected temperature of the second temperature detecting member is fixed during fixing. The first energization control means and the second
Wherein the power supply control means starts power supply at a predetermined timing in response to input of an image formation start signal to the image forming apparatus.