JP2000075715A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a fixing rotating body in a fixing device by optimizing the constitution of the fixing rotating body. SOLUTION: A fixing roller 10a (a fixing rotating body) has a cored bar 31, an elastic body layer 32 formed on the outer circumference of the cored bar 31 to have a thickness of at least 300 μm, and a release layer 33 of a resin material, formed on the outer circumference of the elastic body layer 32. The control temperature of the fixing rotating body is 160 deg.C or more at the time of fixing. In this case, the formula 40>T+0.057(Wd/ϕ1λ) is satisfied, wherein ϕis an external diameter of the cored bar of the fixing roller 10a, [cm]; l is a length of the elastic body layer 32 in the longitudinal direction, [cm]; T is a control temperature of the fixing rotating body, [ deg.C]; W is a heat generating amount of a halogen heater (a heating means), [watt]; and λ is a thermal conductivity of the elastic body layer 32, [cal/sec.cm. deg.C].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine and a printer, and a fixing device used in the image forming apparatus.

[0002]

2. Description of the Related Art In general, as a fixing device in an electrophotographic image forming apparatus, a cylindrical fixing roller provided with a halogen heater as a heating source inside, a silicone rubber or a fluoro rubber on the surface of a cylindrical cored bar. There has been known an apparatus in which a pressure roller covered with an elastic layer made of a material such as the above is arranged to face the pressure roller.

Further, the surfaces of the fixing roller and the pressure roller are often coated with a fluororesin from the viewpoints of toner releasability and abrasion resistance.

Further, due to demands for fixing performance and image quality, many fixing rollers are also covered with an elastic layer. In particular, in order to achieve uniform gloss in the quality of a solid image, at least three elastic layers of the fixing roller are required.
It is known that a thickness of 00 μm or more is necessary.

On the other hand, in recent years, copiers and printers have been increasingly required to operate at higher speeds, and in order to satisfy the demand, it is necessary to improve the low-temperature fixing property of toner and the fixing ability of a fixing device.

[0006]

In order to improve the fixing ability, the simplest and most effective methods are a method of increasing the surface temperature of the fixing roller, a method of increasing the wattage of the heater, and a method of increasing the elastic layer. A method of increasing the fixing nip by increasing the thickness and the pressing force can be considered.

All of these methods increase the amount of heat applied to an unfixed image by a fixing roller to secure the fixing property. However, in any of these methods, silicone rubber or fluorine rubber is used as an elastic layer. In the fixing device using the used fixing roller, there is a problem that the elastic layer is deteriorated due to high temperature at the boundary between the core metal and the elastic layer, and the elastic layer is separated from the core metal. In particular, when the surface temperature of the fixing roller exceeds 160 ° C., it becomes remarkable.

It is also conceivable to increase the outer diameter of the fixing roller in order to improve the fixing ability.

However, in this case, there are problems such as an increase in the size of the fixing device, an increase in cost, and an increase in wait time.

[0010] In order to solve the problems of the prior art, the present invention provides a fixing device and an image forming apparatus capable of greatly improving the durability of a fixing rotating body by optimizing the configuration of a fixing roller. The purpose is to provide.

[0011]

According to the present invention, there is provided a fixing rotator for fixing an unfixed image formed on a recording material in contact with the fixing rotator, and pressing the fixing rotator with the fixing rotator. A fixing device having a pressing rotator, at least a heating unit provided inside the fixing rotator and heating the fixing rotator, a fixing rotator temperature detecting unit for measuring a surface temperature of the fixing rotator, A fixing device comprising: a temperature control unit that maintains the fixing rotator at a predetermined control temperature; and a rotator driving unit that rotationally drives a rotator pair of the fixing rotator and the pressing rotator. The body has a cored bar, an elastic layer having a thickness of at least 300 μm or more on the outer periphery of the cored bar, and further has a release layer made of a resin material on the outer periphery thereof. Control temperature is over 160 ℃ Of the fixing rotator, the outer diameter of the metal core phi [cm], a longitudinal length of the elastic layer l [c
m], the thickness of the elastic layer is d [cm], the control temperature of the fixing rotating body is T [° C.], the calorific value of the heating means is W [watt], and the thermal conductivity of the elastic body is λ [cal / sec]. · Cm · ° C], the relational expression 240> T + 0.057 (Wd / φlλ) is satisfied.

It is also preferable that a fluorine resin is used as the resin material of the release layer.

The image forming apparatus has an image forming means for forming an unfixed image on a recording material, and the unfixed image formed on the recording material is fixed by the fixing device described above.

[0014]

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

FIG. 1 is a cross-sectional view showing a schematic configuration of a digital four-color full-color image forming apparatus as an example of an image forming apparatus according to the present invention.

The image forming apparatus shown in FIG. 1 has a lower digital color image printer section (hereinafter simply referred to as "printer section") I and the above digital color image reader section (hereinafter simply referred to as "reader section") II. For example, based on the image of the document D read by the reader unit II,
An image is formed on the recording material P by the printer unit I.

Hereinafter, the configuration of the printer unit I and subsequently the configuration of the reader unit II will be briefly described.

The printer section I has a photosensitive drum 1 as an image carrier which is driven to rotate in the direction of arrow R1. Around the photosensitive drum 1, the primary charger (charging unit) 2, the exposure unit 3, the developing unit (developing unit) 4, the transfer unit 5, the cleaning unit 6, the pre-exposure lamp 7, etc. Is arranged.

Below the transfer device 5, ie, the printer unit I
In the lower half portion, a paper feeder 8 for the recording material P is disposed, and further, a separating unit 9 is provided above the transfer device 5, and a downstream side of the separating unit 9 (downstream in the conveying direction of the recording material P). (Side), a fixing device 10 and a paper discharge unit 11 are arranged.

The photosensitive drum 1 has a base 1a on an aluminum drum and an OPC (organic optical semiconductor) photosensitive member 1b covering the back side thereof, and is driven in a predetermined direction in an arrow R1 direction by driving means (not shown). It is configured to be driven to rotate at the process speed (peripheral speed). The photosensitive drum 1 will be described later in detail.

The primary charger 2 includes a shield 2a having an opening at a portion facing the photosensitive drum 1, and a discharge wire 2 disposed inside the shield 2a in parallel with the bus of the photosensitive drum 1.
b and a grid 2c arranged in the opening of the shield 2a to regulate the charging potential.

A charging bias is applied to the primary charger 2 by a power supply (not shown), whereby the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and a predetermined potential.

The exposure means 3 includes a laser output section (not shown) for emitting a laser beam based on an image signal from a reader section II described later, and a polygon mirror 3a for reflecting the laser beam.
, A lens 3b, and a mirror 3c.

Exposure means 3 exposes the photosensitive drum 1 by irradiating the surface of the photosensitive drum 1 with the laser beam.
The image forming apparatus is configured to form an electrostatic latent image by removing charges from an exposed portion. In the present embodiment, the electrostatic latent image formed on the surface of the photosensitive drum 1 is yellow,
The image is separated into four colors of cyan, magenta, and black, and an electrostatic latent image corresponding to each color is sequentially formed.

The developing device 4 includes four developing devices in order from the upstream side along the rotation direction of the photosensitive drum 1 (direction of arrow R1), that is, each color of yellow, magenta, cyan, and black, each of which is made of a resin. Developing devices 4Y, 4C, 4M, and 4Bk containing the toner (developer).

Each of the developing units 4Y, 4C, 4M, and 4Bk has a developing sleeve 4a for attaching toner to the electrostatic latent image formed on the surface of the photosensitive drum 1, and is used for developing the electrostatic latent image. A developing device of a predetermined color is alternatively disposed at a developing position close to the surface of the photosensitive drum 1 by the eccentric cam 4b, and attaches the toner to the electrostatic latent image via the developing sleeve 4a. It is configured to form an image (visible image). The three color developing units other than the developing unit used for development are retracted from the developing position.

The transfer device 5 includes a transfer drum (recording material carrying pair) 5a that carries the recording material P on the surface, a transfer charger 5b that transfers the toner image on the photosensitive drum 1 to the recording material P, and a recording material P.
Charger 5c for attracting the toner to the transfer drum 5a, a suction roller 5d opposed thereto, an inner charger 5e, and an outer charger 5f, and the transfer is rotatably driven in the direction of arrow R5. A recording material carrying sheet 5g composed of a dielectric pair is integrally stretched in a cylindrical shape in a peripheral opening area of the drum 5a.

As the recording material supporting sheet 5g, a dielectric sheet such as a polycarbonate film is used. The transfer device 5 is configured to adsorb and carry the recording material P on the surface of the transfer drum 5a.

The cleaning device 6 includes a cleaning blade 6a for scraping off residual toner remaining on the surface of the photosensitive drum 1 without being transferred to the recording material P, and a cleaning container 6b for collecting the scraped toner.

The pre-exposure lamp 7 is disposed adjacent to the upstream side of the primary charger 2 and removes unnecessary charges on the surface of the photosensitive drum 1 cleaned by the cleaner 6.

The paper feed unit 8 includes a plurality of paper feed cassettes 8a for loading and storing recording materials P of different sizes, a paper feed roller 8b for feeding the recording materials P in the paper feed cassette 8a, and a number of feeds. It has a roller, a registration roller 8c and the like, and supplies a recording material P of a predetermined size to the transfer drum 5a.

The separating means 9 is provided for the recording material P after the transfer of the toner image.
Charger 9a for separating the toner from the transfer drum 5a,
It has a separation claw 9b and a separation push-up roller 9c.

The fixing device 10 has a heater (heating means) inside.
A fixing roller 10a as a fixing rotator, and a pressing roller 10 as a pressing rotator disposed below the fixing roller 10a and pressing the recording material P against the fixing roller 10a.
b.

The paper discharge unit 11 includes a conveyance path switching guide 11 a and a discharge roller 11 disposed downstream of the fixing device 10.
b, a paper discharge tray 11c and the like. Further, below the conveyance path switching guide 11a, a conveyance vertical path 11d, a reversing path 11e, a stacking member 11f, an intermediate tray 11g, and a conveyance roller for forming an image on both sides of one recording material P are formed. 11h, 11i, a reversing roller 11j and the like are arranged.

Between the primary charger 2 and the developing device 4 around the photosensitive drum 1, there is provided a potential sensor S1 for detecting the charged potential on the surface of the photosensitive drum, and between the developing device 4 and the transfer drum 5a. Is provided with a density sensor S2 for detecting the density of the toner image on the photosensitive drum 1.

Next, the reader section II will be described. The reader unit II disposed above the printer unit I includes:
An original table glass 12a on which an original D is placed; an exposure lamp 12b for exposing and scanning the image surface of the original D while moving;
A plurality of mirrors 12c that further reflect the reflected light from
It has a lens 12d for condensing the reflected light, a full color sensor 12e for forming a color separation image signal based on the light from the lens 12d, and the like. The color-separated image signal is processed by a video processing unit (not shown) through an amplifier circuit (not shown).
To be sent.

Next, the operation of the above-described image forming apparatus will be described.
A brief description will be given while adding some components. In the following description, it is assumed that four full-color images are formed in the order of yellow, cyan, magenta, and black.

The image of the original D placed on the original platen glass 12a of the reader unit II is irradiated by an exposure lamp 12b, color-separated, and a yellow image is first read by a full-color sensor 12e and subjected to predetermined processing. The image data is sent to the printer unit I as an image signal.

In the printer section I, the photosensitive drum 1 has an arrow R
It is driven to rotate in one direction, and the surface is uniformly charged by the primary charger 2. A laser beam is emitted from a laser output unit of the exposure unit 3 based on the image signal sent from the reader unit II, and the charged photosensitive drum 1 surface is exposed by a light image E via a polygon mirror 3a and the like. .

The exposed portion of the surface of the photosensitive drum 1 is
The charge is removed, thereby forming an electrostatic image corresponding to yellow. In the developing device 4, the yellow developing device 4Y is disposed at a predetermined developing position, and the other developing devices 4C, 4M, and 4Bk are retracted from the developing position.

The electrostatic latent image on the photosensitive drum 1 is transferred to the developing device 4Y
As a result, yellow toner is adhered to the toner, and the toner is visualized to form a toner image. The yellow toner image on the photosensitive drum 1 is transferred to the recording material P carried on the transfer drum 5a.

The recording material P is transferred to the transfer drum 5a at a predetermined timing from a predetermined paper feeding cassette 8a having a size suitable for a document image via a paper feeding roller 8b, a conveying roller, and a registration roller 8c. Supplied.

The recording material P supplied in this manner is adsorbed so as to be wound around the surface of the transfer drum 5a, and the arrow R5
, And the yellow toner image on the photosensitive drum 1 is transferred by the transfer charger 5b.

On the other hand, the photosensitive drum 1 after the transfer of the toner image
The residual toner on the surface is removed by the cleaning device 6, and unnecessary charges are further removed by the pre-exposure lamp 7 to be used for the next image formation starting from the primary charger.

The processes from the reading of the original image by the reader unit II, the transfer of the toner image to the recording material P on the transfer drum 5a, the cleaning of the photosensitive drum 1, and the neutralization are performed in other colors than yellow. Ie, cyan,
The same applies to magenta and black, and the toner images of four colors are transferred onto the recording material P on the transfer drum 5a so as to overlap.

Recording material P to which four color toner images have been transferred
Is separated from the transfer drum 5a by a separation charger 9a, a separation claw 9b, and the like, and is conveyed to the fixing device 10 with an unfixed toner image carried on the surface.

The recording material P is applied to the fixing roller 10 of the fixing device 10.
a and the pressure roller 10b heat and pressurize, and the toner image on the surface is fused and fixed. The recording material P after the fixing is discharged onto a discharge tray 11c by a discharge roller 11b.

When an image is formed on both sides of the recording material P, the fixing device 10 immediately drives the transport path switching guide 11a to transport the discharged recording material P, passes through the transport vertical path 11d, and turns over the reverse path. 11e, the reversing roller 11
j is reversed in a reverse direction to the direction in which the sheet is fed, with the rear end when the sheet is fed in reverse, and the intermediate tray 11g
To be stored. Then, after an image is formed on the other surface again by the above-described image forming process,
Discharge on c.

On the transfer drum 5a after the separation of the recording material P, the recording material supporting sheet 5g is used to prevent scattering of powder on the recording material supporting sheet 5g and adhesion of oil on the recording material P. Fur brush 1 facing each other through
Cleaning is performed by 3a and the backup brush 13b, and by the oil removing roller 14a and the backup brush 14b. Such cleaning is performed before or after image formation, and is performed as needed when a jam (paper jam) occurs.

Next, the relational expression of the present invention will be described.

The thermal resistance R of the elastic layer of the fixing roller 10a
Considering [sec · ° C./cal], it can be expressed as R = (d / λA).

Here, λ is the thermal conductivity of the elastic body [cal /
sec · cm · ° C], A is the surface area of the roller core metal [c
m ² ] and d are the thickness [cm] of the elastic layer.

Next, the surface temperature T1 of the fixing roller 10a
And the boundary temperature T2 between the core metal and the elastic layer can be expressed as T2-T1 = QR = Qd / Aλ.

Here, since Q / A can be considered as a heat flow per unit area flowing from the core metal to the elastic layer, Q / A = 1 / 4.186 (W / πφ1) κ = 46. 4κ
(W / φl).

Here, W is the calorific value of the halogen heater [J
/Sec=1/4.186 cal / sec], φ represents the outer diameter [cm] of the core of the fixing roller 10a, and κ represents the heat transfer efficiency from the halogen heater to the surface of the core.

Therefore, the above relational expression can be expressed as T2-T1 = 46.4κ (Wd / φlλ). Next, an example of a method for determining the heat transfer efficiency κ will be described with reference to FIG.

In the figure, the fixing roller 10a is a hollow iron core metal 3 having a thickness of 0.7 mm and an outer diameter of 37.6 mm.
A silicone rubber layer having a thickness of 1.2 mm is provided as an elastic body layer 32 on the top of the base material 1, and PFA (tetrafluoroethylene-perfluoroalkylvinyl ether copolymer) which is a 50-μm-thick fluorine-based resin is provided as a release layer 33 on the outside thereof. It has a tube layer and has a diameter of 40 mm.

The thermal conductivity of the silicone rubber used for the elastic layer 32 is 1.0 × 10 ⁻³ cal / sec · cm.
・ It is ° C. Further, the fixing roller 10a and the pressure roller 10
b has a length of 314 mm in the longitudinal direction, and is provided with an elastic layer and a release layer.

On the other hand, the pressure roller 10b has a 5 mm thick silicone rubber layer 35 on a solid iron core 34 and a 50 μm thick PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether) as a release layer. (Polymer) A tube layer 36 is provided and has a diameter of 30 mm.

The above-described fixing roller 10a has a heating value of 60
A halogen heater 37 of 0 watts is provided in the cored bar 31. The fixing roller 10a is fixed by a thermistor 38 as a fixing rotating body temperature detecting means provided on the fixing roller 10a.
The halogen heater 37 is controlled by the control device 39, which is a temperature control means, based on the detected temperature, so that the temperature of the fixing roller 10a is maintained at a predetermined temperature.

The fixing roller 10a and the pressure roller 10
b is pressurized at a total pressure of about 30 kg by a pressurizing mechanism (not shown).

A thermocouple 40 is provided on the boundary surface so that the boundary temperature between the core metal 31 and the elastic layer 32 can be measured.

The fixing roller 10a and the pressure roller 10
b rotates at a process speed of 150 mm / sec. Further, the fixing roller 10a and the pressure roller 10b
Each has a length of 314 mm in the longitudinal direction, and is provided with an elastic layer and a release layer.

In the fixing device 10 described above, the recording material P carrying the unfixed toner image on its surface is nipped and conveyed to a fixing nip between the fixing roller 10a and the pressure roller 10b, and is heated and pressurized at this time. Is fixed.

In the above configuration, the difference between the fixing roller surface temperature T1 and the boundary temperature T2 between the core metal and the elastic layer, and T1
Table 1 summarizes the heat transfer efficiency κ determined by T2 and T2 and the evaluation of the fixability under the conditions.

[0066]

[Table 1] From the average value of the above results, the heat transfer efficiency κ was determined to be 0.754.

In the above method, even if the material and outer diameter of the metal core, the material and thickness of the elastic layer, the material and thickness of the release layer of the fixing roller, and the calorific value of the halogen heater are changed. The heat transfer efficiency κ was almost the same value.

As described above, the surface temperature T1 of the fixing roller is
It is considered that the boundary temperature T2 between the core metal and the elastic layer can be expressed as T2-T1 + 0.057 (Wd / φlλ).

Then, according to the embodiment described below, the boundary temperature is preferably set to 230 ° C. so as to be lower than 240 ° C.
It has been found that by determining various parameters as described below, it is possible to suppress the occurrence of peeling of the elastic layer from the core metal.

(Embodiment 1) In the configuration of Embodiment 1, the surface temperature of the fixing roller 10a was set to 190 ° C. in the configuration used in the above-described method for determining the heat transfer efficiency κ, and continuous paper passing durability was performed. .

When the structure of the first embodiment is applied to the relational expression of the present invention, the boundary temperature can be estimated to be about 225 ° C.

When the paper-passing durability was actually performed by the image forming apparatus using the fixing device configuration of the first embodiment, no peeling of the elastic layer occurred even when 300,000 sheets or more were passed.

As Comparative Example 1, the surface temperature of the fixing roller was set to 205 ° C. in Example 1. in this case,
When applied to the relational expression of the present invention, the boundary temperature was about 240 ° C., and as a result of paper passing durability, the elastic layer was separated from the core metal on about 70,000 sheets.

In the first embodiment, the PFA tube is used for the release layer of the fixing roller 10a and the pressure roller 10b.
Other fluororesins such as TFE) may be used.

The core metal of the fixing roller and the pressure roller may be other metals such as aluminum and stainless steel.

In the first embodiment, the number of halogen heaters in the fixing roller is one. However, in a fixing device having a plurality of halogen heaters having different heating values in the fixing roller, a halogen heater having a large heating value is used. The present invention can be applied by using the numerical values of

Further, in the first embodiment, the heating source of the fixing device is provided only in the fixing roller. However, in the fixing device configuration in which the heating source is provided also in the pressure roller,
The same applies.

(Example 2) Next, as Example 2, the thickness of the elastic layer was set to 1.5 mm in Example 1 described above.
In this case, when applied to the relational expression of the present invention, the boundary temperature was about 234 ° C., and as a result of paper passing durability, the elastic layer was separated from the core metal on about 200,000 sheets.

As Comparative Example 2, the fixing roller had a surface temperature of 200 ° C. in the configuration of Example 2. In this case, the boundary temperature is about 24 when applied to the relational expression of the present invention.
At 4 ° C., the elastic layer peeled off from the metal core on about 50,000 sheets as a result of paper passing durability.

(Embodiment 3) Next, as Embodiment 3, the heat value of the halogen heater was set to 900 W in Embodiment 1 described above. In this case, when applied to the relational expression of the present invention, the boundary temperature was about 233 ° C., and as a result of paper passing durability, the elastic layer was separated from the core metal on about 200,000 sheets.

As Comparative Example 3, the thickness of the elastic layer in Example 3 was set to 1.0 mm. In this case, when applied to the relational expression of the present invention, the boundary temperature was about 224 ° C., and as a result of the paper passing durability, the peeling of the elastic layer did not occur even when 300,000 sheets or more were passed.

(Embodiment 4) In this embodiment 4, in the above-mentioned embodiment 1, the elastic layer has a thermal conductivity of 1.7 × 1.
Silicone rubber of 0 ⁻³ cal / sec · cm · ° C. was used. Further, since the hardness of the above silicone rubber was higher than that of the silicone rubber used in Example 1, the thickness of the elastic layer was set to 1.5 mm.

In this case, when applied to the relational expression of the present invention, the boundary temperature was about 215 ° C., and the elastic layer did not deteriorate even when 300,000 sheets or more were passed as a result of paper passing durability.

As Comparative Example 4, the fixing roller surface temperature was set to 210 ° C. in Example 4. in this case,
When applied to the relational expression of the present invention, the boundary temperature was about 235 ° C., and as a result of paper passing durability, the elastic layer was separated from the core metal on about 180,000 sheets.

Fifth Embodiment In the fifth embodiment, the outer diameter of the fixing roller core is set to 50 mm in the first embodiment. In this case, when applied to the relational expression of the present invention, the boundary temperature was about 216 ° C., and the elastic layer did not peel off even when 300,000 sheets or more were passed as a result of paper passing durability.

In Comparative Example 5, the outer diameter of the fixing roller core was 35 mm in Example 5. In this case, when applied to the relational expression of the present invention, the boundary temperature is about 227.
° C, and as a result of paper passing durability, the elastic layer was peeled off from the core metal on about 220,000 sheets.

(Embodiment 6) Embodiment 6 is different from Embodiment 1 described above.
In the above, the length in the longitudinal direction of the elastic layer and the release layer coated on the metal core was set to 230 mm, and the heat generation area of the halogen heater was also set to about 230 mm. In this case, the boundary temperature is about 2 when applied to the relational expression of the present invention.
The temperature was 37 ° C., and as a result of paper passing durability, the elastic layer was peeled off from the core metal on 120,000 sheets.

As Comparative Example 6, the fixing roller had a surface temperature of 180 ° C. in Example 6. In this case, when applied to the relational expression of the present invention, the boundary temperature was about 227 ° C., and as a result of the paper passing durability, the elastic layer was separated from the core metal in about 230,000 sheets.

[0089]

As described above, the boundary temperature between the core metal and the elastic layer obtained by the relational expression of the present invention is set to be lower than 240 ° C., preferably not higher than 230 ° C.
By optimizing the configuration of the fixing roller, the durability of the fixing roller can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a fixing roller according to an embodiment when determining a heat transfer efficiency κ in the present invention.

[Explanation of symbols]

 I Digital color image printer section II Digital color image reader section 10 Fixing device 10a Fixing roller (fixing rotating body) 10b Pressure roller (pressing rotating body) 31 Core bar 32 Elastic layer 33 Release layer 37 Halogen heater (heating means) 38) Thermistor (Fusing rotating body temperature detecting means) 39 Controller (Temperature controlling means) 40 Thermocouple

Claims (3)

[Claims] A fixing rotator that contacts and fixes an unfixed image formed on a recording material; a pressurizing rotator that is in pressure contact with the fixing rotator; A fixing device having heating means for heating the rotating body, a fixing rotating body temperature detecting means for measuring a surface temperature of the fixing rotating body, a temperature control means for maintaining the fixing rotating body at a predetermined control temperature, A rotating body driving unit that rotationally drives a rotating body pair of a fixing rotating body and a pressure rotating body, wherein the fixing rotating body has a core bar and a thickness of at least 300 μm or more around the core bar. An elastic layer, and a release layer made of a resin material on the outer periphery of the elastic layer;
60 ° C. or more, and the outer diameter of the core metal of the fixing rotating body is φ
[Cm], the length of the elastic layer in the longitudinal direction is 1 [cm], the thickness of the elastic layer is d [cm], and the control temperature of the fixing rotator is T.
[C], the heating value of the heating means is W [watt], and the thermal conductivity of the elastic body is λ [cal / sec · cm · ° C.], the relational expression of 240> T + 0.057 (Wd / φlλ) is obtained. A fixing device characterized by satisfying. 2. The fixing device according to claim 1, wherein a fluorine resin is used as a resin material of the release layer. 3. An image forming means for forming an unfixed image on a recording material, wherein the unfixed image formed on the recording material is fixed by the fixing device according to claim 1. Image forming device.