JPH09292790A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a heating device capable of furnishing a quick starting performance, saving energy consumption, equipping the excellent temp. stability/ temp. controlling performance, and satisfactorily corresponding to a high speed machine kind and the color image forming device as the heat-fixing device, with regard to the heating device of an electrmagnetic heating system. SOLUTION: This heating device 100, provided with the electromagnetic induction heat generating film 36 and the electromagnetic induction heat generating pressure member 4 being held in press contact with each other, and at least one alternating current generating means 34 and 41 for imparting the alternating magnetic field on the film 36 and the pressure member 4, is composed so as to make the heat receiving material P held-transported by a press contact nip part N in-between the film and the pressure material, and to heat the heat receiving material by the above film electromagnetic induction heat generated by the alternating magnetic field generating means and the pressure member. Then, the temp. of the film is detected by temp. sensors S1, S2 and S3 for controlling the temp., arranged at least one side on the upstream side and the downstream side in the heat receiving material transporting direction at the pressure nip part N of the film 36 and the pressure member 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic (magnetic) induction heating type heating device and an image forming apparatus provided with the heating device as an image heating and fixing device.

[0002]

2. Description of the Related Art For convenience of description, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, a recording material such as a transfer material, a photosensitive paper or an electrostatic recording paper is formed and carried by a transfer (indirect) method or a direct method. An image heating and fixing device as a heating device for heating and fixing the unfixed toner image will be described as an example.

Conventionally, a heat roller type apparatus has been widely used as an image heating and fixing apparatus. A film heating type device has also been put into practical use. Electromagnetic induction heating type devices are also known.

A. Heat roller type device A halogen heater (halogen lamp) as a heat source is built in, and a fixing roller (heat roller) which is heated and regulated to a predetermined temperature by the heat of the halogen heater is brought into pressure contact with a pressure roller. A fixing nip portion is formed, the roller pair is rotated, and a recording material having an unfixed toner image as a material to be heated, which is a material to be heated, is introduced into the fixing nip portion and is nipped and conveyed. The recording material is heated by the heat of the fixing roller to thermally fix the image.

B. Film heating type device As disclosed in Japanese Patent Laid-Open No. 63-313182, a heat resistant film is sandwiched between a generally ceramic heater as a heat source (heating body) and a pressure roller as a pressure member. The heat-resistant film is formed by forming a fixing nip portion and introducing a recording material carrying an unfixed toner image as a material to be heated between the heat-resistant film and the pressure roller in the fixing nip portion. When the fixing nip portion is nipped and conveyed together, the heat of the ceramic heater, which generates heat when the heating resistor is energized, is applied to the recording material via the heat-resistant film to heat the recording material for thermal fixing of the image. is there.

C. Electromagnetic induction heating system device In Japanese Patent Publication No. 5-9027, Joule heat is generated by generating an eddy current by an alternating magnetic field generated by an alternating magnetic field generating means in a core metal portion of a fixing roller of a roller pair of a fixing roller and a pressure roller. There has been proposed a device for electromagnetically heating the fixing roller to a predetermined temperature by causing the core metal portion of the fixing roller to generate heat.

[0007]

In the apparatus of the heat roller system of the above item a, a fixing roller having a large heat capacity is heated, and a halogen heater as a heat source converts electric energy into light once. Due to the poor efficiency, the quick start was not possible even with the best efficiency. Moreover, the power consumption was large.

In the case of image heat fixing in a color image forming apparatus, an unfixed toner image formed by superposing a maximum of four toner layers on the surface of a recording material is a recording material and a toner layer having a thickness. If the interface with the toner layer is not heated sufficiently, fixing failure will occur.

Therefore, in the heat roller type heat fixing device for a color image, a halogen heater is also incorporated in the pressure roller so that the pressure roller is also heated. However, even in this case, the fixing roller and the pressure roller are also heated. Due to its large heat capacity, quick start cannot be realized, and power consumption will be even greater.

The film heating type device of the item b can use a heater as a heat source or a heat resistant film having a low heat capacity, has a quick start property, and can be a power saving device.

However, there is a limit to increasing the total amount of heat generation, and it is suitable for a fixing device in an image forming apparatus of a medium speed / low speed model, and a heat amount is insufficient as a fixing device in a high speed model or a color image forming apparatus. There are difficulties.

The eddy current is generated by the alternating magnetic field generated by the alternating magnetic field generating means in the core metal portion of the fixing roller of the roller pair of the fixing roller and the pressure roller as the apparatus of the electromagnetic induction heating system of the above item c. An apparatus that electromagnetically heats the fixing roller to a predetermined temperature by heating the core metal of the fixing roller with Joule heat can bring the heat generation position closer to the toner, and uses a heat roller system that uses a halogen lamp as a heat source. The efficiency of energy consumption can be improved more than that of the device.

However, in the case of this apparatus as well, the heat capacity of the fixing roller is large, so that the quick start property is insufficient. When an eddy current is generated in the cylindrical fixing roller by an alternating magnetic field to generate Joule heat, the exciting coil / exciting iron core as an alternating magnetic field generating means arranged in the fixing roller is heated to increase the amount of magnetic flux. Is reduced and heat generation becomes unstable. Further, if the temperature rise is large, the excitation coil will be deteriorated. Further, the heat efficiency is not sufficient due to the heat radiation to the inside of the fixing roller.

Therefore, the present invention particularly relates to an electromagnetic heating type heating device having a quick start property, energy saving type, good temperature stability and temperature controllability, and a high speed model as a heat fixing device, a color image forming apparatus. It is an object of the present invention to provide a heating device capable of sufficiently coping with the above, and an image forming apparatus including the heating device as an image heating device.

[0015]

According to the present invention, there is provided a heating apparatus and an image forming apparatus having the following constitutions.

(1) An electromagnetic induction heat-generating film and an electromagnetic induction heat-generating pressure member, which are pressed against each other, and at least one alternating magnetic field generating means for applying an alternating magnetic field to the film and the pressure member. A heating device that heats and heats the material to be heated by the film and the pressure member that are heated by electromagnetic induction by the alternating magnetic field of the alternating magnetic field generating means by sandwiching and transporting the material to be heated in the pressure contact nip part of the pressure member. The temperature sensor for control is arranged on at least one of an upstream side and a downstream side in a material-to-be-heated conveying direction of a pressure contact nip portion between the film and the pressure member, and detects the temperature of the film.

(2) In the heating device described in (1) above, the temperature sensors for controlling the temperature are arranged on the upstream side and the downstream side of the heated material conveying direction in the pressure nip portion between the film and the pressing member. The heating device is characterized in that the heat generation amount of the film and the pressing member is controlled by controlling the current or voltage applied to the alternating magnetic field generating means according to the difference between the temperatures detected by the both temperature sensors.

(3) An electromagnetic induction heat generating film and an electromagnetic induction heat generating pressure member which are pressed against each other, and at least one alternating magnetic field generating means for introducing an alternating magnetic field into the film and the pressure member. A heating device that heats and heats the material to be heated by the film and the pressure member that are heated by electromagnetic induction by the alternating magnetic field of the alternating magnetic field generating means by sandwiching and transporting the material to be heated in the pressure contact nip part of the pressure member. The temperature sensor for control is arranged on at least one of the upstream side and the downstream side of the pressure-contact nip portion between the film and the pressure member in the direction of transport of the heated material, and the temperature of the film and the pressure member, respectively. A heating device which is characterized by detecting.

(4) In the heating device described in (3) above, the temperature detected by each temperature sensor is arithmetically processed and applied to at least one of the alternating magnetic field generating means on the film side and the pressing member side. A heating device in which the amount of heat generated by the film and the pressing member is controlled by controlling the applied current or voltage.

(5) Any one of (1) to (4) above
In the heating device according to the third aspect, the temperature sensor for detecting the temperature of the film is arranged on the inner surface side of the film, which is the surface opposite to the pressure member side of the film. apparatus.

(6) Any one of (1) to (5) above
In the heating device according to the third aspect of the present invention, the metal constituting member other than the film and the pressing member, which is affected by the alternating magnetic field generated by the alternating magnetic field generating means, is a non-magnetic material. apparatus.

(7) Any one of (1) to (6) above
In the heating device according to the third aspect, the material to be heated is a recording material to be image-heated and fixed, and an unfixed image is formed and carried on one surface of the recording material, and the one surface side is introduced into the apparatus as a film side. Then, the image is heated and fixed on the one surface, and
When the image-fixing of the first side of the recording material is carried out when an unfixed image is formed and carried on the surface and the second side is made into the film side and is re-introduced into the apparatus to perform the image heat-fixing of the second side. The heat generation amount Q1 on the film side and the heat generation amount Q2 on the pressure member side are Q1 <Q2, and Q1> Q2 when the image heat fixing of the second surface of the recording material is performed.

(8) Any one of (1) to (7) above
In the heating device according to the third aspect, the maximum size width WP of the material to be heated, the coil width WC for generating the alternating magnetic field of the alternating magnetic field generating means, the film width WF, and the pressing member width WK are as follows: WP <WK <WF <WC, The heating apparatus characterized by the above-mentioned.

(9) An image forming apparatus having an image forming means for forming and carrying an unfixed image on a recording material and a heat fixing means for heating and fixing the unfixed image on the recording material.
An image forming apparatus, wherein the heat fixing unit is the heating device described in any one of (1) to (8) above.

<Operation> a) A temperature sensor for detecting the temperature of the film for controlling the temperature is at least one of the upstream side and the downstream side of the pressure-contact nip portion between the film and the pressing member in the direction in which the material to be heated is conveyed. By arranging in the above, it becomes possible to quickly and accurately control the heat generation amount of a thin film having a small heat capacity.

B) Temperature sensors for temperature control, which detect the temperature of the film, are arranged on the upstream side and the downstream side of the heated material conveying direction in the pressure nip portion between the film and the pressing member,
In the image heating and fixing device, temperature control is performed by the difference in the detected temperature, and when the amount of heat generated during fixing changes due to the type of recording material, the density of the toner image, the surrounding environment, etc. However, it is possible to detect the change in the required heat generation amount and control the temperature.

C) By providing a temperature sensor for detecting the temperature of the film and a temperature sensor for detecting the temperature of the pressing member, in the image heating and fixing device, the phase of the type of recording material and the density of the toner image can be changed. It is possible to more accurately perform temperature control to make the fixing property, gloss, and the like uniform according to environmental changes.

D) At least one of the alternating magnetic field generating means on the film side and the pressing member side is subjected to arithmetic processing of the detected temperature of the temperature sensor for detecting the temperature of the film and the detected temperature of the temperature sensor for detecting the temperature of the pressing member. Image heating and fixing by controlling the current or voltage applied to the alternating magnetic field generating means to control the heat generation amount of the film and / or the pressure member to control the temperature of at least one of the film and the pressure member. In the apparatus, it is possible to perform temperature control so that a uniform fixed image can always be obtained even if the type of recording material, the density of the toner image, and the surrounding environment change.

E) Device members other than the film and the pressing member, which are metallic members that are affected by the alternating magnetic field generated by the alternating magnetic field generating means, are provided in the image heating and fixing device by using a non-magnetic material. As a result, it is possible to prevent heat generation in a portion necessary for heat-fixing the toner image on the recording material, reduce power consumption, and facilitate quick start.

F) The material to be heated is a recording material to be image-heated and fixed, and an unfixed image is formed and carried on one surface of the recording material, and the one surface side is introduced into the apparatus as the film side. Image heating and fixing of one surface is performed, and unfixed images are formed and carried on two surfaces of the recording material, and the two surfaces are re-introduced into the apparatus with the film side facing the two surfaces to perform image heating and fixing of the two surfaces. If you want to
The heat generation amount Q1 on the film side and the heat generation amount Q2 on the pressure member side at the time of image heat fixing of the first surface of the recording material are set to Q1 <Q2 so that the amount of heat directly applied to the toner image is reduced, It becomes possible to stably obtain a fixed image whose gloss is suppressed on the first surface. Further, by setting Q1> Q2 at the time of image heat fixing of the second surface of the recording material, the second surface of the recording material is not disturbed even when fixing the second surface of the recording material and the second surface is clear. It is possible to obtain a fixed image.

G) The relationship between the maximum size width WP of the material to be heated, the coil width WC for generating the alternating magnetic field of the alternating magnetic field generating means, the film width WF, and the pressing member width WK is WP <WK
By setting <WF <WC, it becomes possible to realize a film-type electromagnetic induction heating device that heats the film and the pressing member by the alternating magnetic field.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Example of image forming apparatus FIG. 1 is a schematic configuration diagram of an example of the image forming apparatus. The image forming apparatus of this example is a four-color electrophotographic color printer.

Reference numeral 101 denotes an electrophotographic photosensitive drum (image bearing member) made of an organic photosensitive member or amorphous silicon,
It is rotationally driven at a predetermined process speed (peripheral speed) in the clockwise direction indicated by the arrow.

The photosensitive drum 101 is uniformly charged with a predetermined polarity and potential by a charging device 102 such as a charging roller during its rotation process.

Then, the charged surface is subjected to scanning exposure processing of the target image information by the laser beam 103 output from the laser scanner 110. Laser scanner 11
Reference numeral 0 denotes a laser beam 103 modulated (on / off) corresponding to a time-series electric digital pixel signal of target image information from an image signal generating device such as an image reading device (not shown) to output a rotating photosensitive drum surface. Scanning exposure is performed, and an electrostatic latent image corresponding to target image information scanned and exposed on the surface of the rotating photosensitive drum 101 is formed by the scanning exposure. Reference numeral 109 denotes an output laser beam from the laser scanner 110 to the photosensitive drum 1.
This is a mirror that deflects to the exposure position 01.

In the case of forming a full-color image, scanning exposure / latent image formation is performed on the first color-separated component image of the target full-color image, for example, the yellow component image, and the latent image is included in the four-color developing device 104. By the operation of the yellow developing device 104Y, a yellow toner image is developed. The yellow toner image is transferred to the surface of the intermediate transfer drum 105 at a primary transfer portion T1, which is a contact portion (or a close portion) between the photosensitive drum 101 and the intermediate transfer drum 105. After the transfer of the toner image to the surface of the intermediate transfer drum 105, the surface of the rotating photosensitive drum 101 is
7 removes adhered residues such as transfer residual toner and is cleaned.

The process cycle of charging, scanning exposure, development, primary transfer, and cleaning as described above is performed on the target full-color image by the second color separation component image (for example, the magenta component image, the magenta developing device 104M operates), Third color separation component image (for example, cyan component image, cyan developing device 104C
Operates), a fourth color separation component image (for example, a black component image,
(The black developing device 104BK is activated) for each color separation component image, and the toner images of four colors of a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially superimposed on the surface of the intermediate transfer drum 105. Is transferred to form a color toner image corresponding to the desired full-color image.

The intermediate transfer body drum 105 has an elastic layer having a medium resistance and a surface layer having a high resistance on a metal drum. The intermediate transfer body drum 105 is in contact with or in proximity to the photosensitive drum 101.
01, is driven to rotate in the counterclockwise direction indicated by an arrow at substantially the same peripheral speed as that shown in FIG. The image is transferred to the surface of the intermediate transfer drum 105.

The color toner image synthetically formed on the surface of the rotary intermediate transfer drum 105 is subjected to the secondary transfer at the secondary transfer portion T2 which is a contact nip portion between the rotary intermediate transfer drum 105 and the transfer roller 106. The recording material P fed into the transfer portion T2 from a paper feeding portion (not shown) at a predetermined timing.
Will be transferred to the surface. The transfer roller 106 is a recording material P.
By supplying an electric charge having a polarity opposite to that of the toner from the back surface of the image forming apparatus, the composite color toner images are sequentially and collectively transferred from the surface of the intermediate transfer drum 105 to the recording material P side.

The recording material P that has passed through the secondary transfer portion T2 is separated from the surface of the intermediate transfer body drum 105 and introduced into the image heating and fixing device 100, and subjected to the heat fixing process of the unfixed toner image to form a color image. The product is discharged to a paper discharge tray (not shown) outside the machine. The image heating and fixing device 100 will be described in detail in the next section (2).

After the transfer of the color toner image onto the recording material P, the rotary intermediate transfer body drum 105 is cleaned by the cleaner 108 after removing the transfer residual toner, adhering residues such as paper dust and the like. The cleaner 108 is normally kept in a non-contact state with the intermediate transfer drum 105, and is kept in contact with the intermediate transfer drum 105 in the process of performing the secondary transfer of the color toner image from the intermediate transfer drum 105 to the recording material P. Is held.

The transfer roller 106 is also always held in a non-contact state with the intermediate transfer body drum 105, and in the process of executing the secondary transfer of the color toner image from the intermediate transfer body drum 105 to the recording material P, the intermediate transfer body drum 105. 105
Is kept in contact with the recording material P via the recording material P.

A print mode for a monochrome image such as a monochrome image can also be executed. Also, a double-sided image print mode or a multiple image print mode can be executed.

In the double-sided image print mode, the recording material P on which the first side image has been printed, which has exited the image heating and fixing device 100, is turned upside down via a recirculation / conveyance mechanism (not shown) and is again transferred to the secondary transfer portion T2. Is sent to the image heating and fixing device 100, the toner image is transferred to the two surfaces, the toner image is transferred to the image heating and fixing device 100 again, and the toner image is fixed to the two surfaces.

In the case of the multiple image print mode, the recording material P, which has exited the image heating and fixing device 100 and on which the first image has been printed, is not turned over again through the recirculation transport mechanism (not shown) and is again transferred to the secondary transfer portion. After being sent to T2, the second toner image transfer is received on the surface on which the first image is printed, and again,
The multiple image print is output by being introduced into the image heating and fixing device 100 and undergoing the second toner image fixing process.

(2) Image heating and fixing device 100 A) Overall schematic configuration of the device FIG. 2 is an external perspective view of the device 100, FIG. 3 is an exploded perspective view, and FIG. 4 is an enlarged cross-sectional model view.

1 is a device lower frame, 2 is a device upper frame, 3 is a fixing film unit, 4 is a pressure roller as a pressure member, 5 is a recording material inlet side guide member, and 6 is the same outlet side lower guide member. , 7 are the same as above. The pressure roller 4, the recording material inlet side guide member 5, and the outlet side lower guide member 6 are disposed on the apparatus lower frame 1 side. The recording material exit side upper guide member 7 is disposed on the apparatus upper frame 2 side. The recording material exit side lower guide member 6 is provided with a recording material discharging and conveying roller 6a.

The pressure roller 4 has shaft portions 4a, 4 on both end sides thereof.
a is dropped from above into the upper open bearing holes provided in the upper side plates on the front side and the rear side of the device lower frame 1, respectively,
The bearing members 4b are externally fitted to the flange portions of both shaft portions, and the bearing members 4b are locked and held in the bearing holes of the side plates on the respective sides, so that the bearings are rotatably held between the side plates. The structure of the pressure roller 4 will be described in detail later in section C).

After the pressure roller 4 is bearing-supported between the side plates of the apparatus lower frame 1 in the above manner, the fixing film unit 3 and the both ends of the guide stays 35 of the unit are located in front of the apparatus lower frame 1. It is placed in the upper open bearing holes of the side plates on the side and the back side from above and is arranged above the pressure roller 4 between the side plates. The structure of the fixing film unit 3 will be described in detail in the following section B).

Then, the device upper frame 2 is placed on the device lower frame 1. At this time, the sloped cam edges 2a provided on the lower side plates on the front and rear sides of the apparatus upper frame 2 interfere with the pin shafts 35a provided on both ends of the guide stay 35 of the fixing film unit 3, respectively. By further pushing down the apparatus upper frame 2 with respect to the apparatus lower frame 1, a pushing down force acts on the pin shaft 35a from the inclined cam edge 2a, and the fixing film unit 3 and the pressure roller 4 are brought into pressure contact with each other, and between them. Fixing nip (pressing nip,
A heating nip portion) N is formed. Therefore, the amount by which the upper frame 2 of the apparatus is pushed down is adjusted to bring the fixing film unit 3 and the pressure roller 4 into pressure contact with a predetermined pressure contact force and the width of the fixing nip portion. The downward side plates are fixed to the upward side plates on the front side and the rear side of the device lower frame 1 by fixing means such as screws, so that both frame 1
The two are joined together.

In FIG. 2, G3 is a pressure roller gear, which is fixedly disposed on one end side of the shaft 4a of the pressure roller 4. G7 is a recording material discharge / conveyance roller gear, and is a recording material discharge / conveyance roller 6 of the recording material exit side lower guide member 6.
It is fixedly provided on one end side of the shaft 6b of a. G1 ・ G
2, G4, G5, and G6 are gear trains pivotally attached to the outer surface of the side plate on one side of the apparatus lower frame 1, and the gear G1 is connected to the pressure roller gear G3 via the gear G2. Further, the pressure roller gear G3 and the recording material conveying roller gear G7 are connected via gears G4, G5, G6.

A drive gear (not shown) on the main body of the image forming apparatus is connected to the gear G1, and the rotational force of the drive gear is transmitted to the pressure roller gear G3 via the gear G2, whereby the pressure roller 4 is pressed. Is rotationally driven in the clockwise direction indicated by the arrow in FIG. 4 at a predetermined peripheral speed. In conjunction with this,
The rotational force of the pressure roller gear G3 is transmitted to the recording material discharging and conveying roller gear G7 via the gears G4, G5, G6,
The recording material discharge / conveyance roller 6a of the recording material exit side lower guide member 6 is rotationally driven in a clockwise direction indicated by an arrow in FIG. 4 at a predetermined peripheral speed.

As the pressure roller 4 is rotationally driven, the cylindrical fixing film 36, which will be described later, of the fixing film unit 3 is fixed to the fixing nip portion N which is a pressure contact portion between the fixing film unit 3 and the pressure roller 4. The rotational force acts on the cylindrical fixing film due to the frictional force between the rotary pressure roller and the outer surface of the fixing film, and the cylindrical film 36 moves around the outer periphery of the film guide member 31 of the fixing film unit 3 which will be described later. While sliding on the underside of
At, the counterclockwise direction is indicated by the peripheral speed substantially corresponding to the peripheral speed of the pressure roller 4.

As will be described later, the fixing film 36 is a member having an electromagnetic induction heat generation property, and is mainly fixed by the action of the alternating magnetic field generated by the first alternating magnetic field generating means 34 arranged inside the film guide member 31. Electromagnetic induction heats up at.

The pressure roller 4 is also a member having an electromagnetic induction heat generating property as described later, and generates electromagnetic induction heat by the action of the alternating magnetic field generated by the second alternating magnetic field generating means 41 arranged in the roller.

Thus, the pressure roller 4 is rotationally driven, the cylindrical fixing film 36 is rotated accordingly, and the fixing film 36 and the pressure roller 4 are electromagnetically heated / controlled to a predetermined temperature. In the recording material P, the recording material P carrying the unfixed toner image, which has passed through the recording material inlet side guide member 5 and has entered the apparatus 100, is fixed in the fixing film 3 in the fixing nip portion N.
The unfixed toner image bearing surface is introduced between the pressure roller 6 and the pressure roller 4 facing upward, that is, facing the surface of the fixing film, and is brought into close contact with the outer surface of the fixing film at the fixing nip portion N and fixed together with the fixing film 36. The nip portion N is nipped and conveyed.
In the process of nipping and conveying the recording material together with the fixing film 36 through the fixing nip portion N, the recording material is heated from both front and back sides by heat of electromagnetic induction heat generation of the fixing film 36 and the pressure roller 4, The unfixed toner image on the recording material is heat-fixed. When the recording material passes through the fixing nip portion N, the recording material is separated from the outer surface of the rotary fixing film 36 and is discharged and conveyed through a space between the recording material outlet side lower guide member 6 and the upper guide member 7 having a discharging and conveying roller 6a. Go.

B) Fixing Film Unit 3 The fixing film unit 3 is mainly composed of the following members.

A. A laterally elongated gutter-shaped gutter-shaped film guide member 31 made of highly heat-resistant composite resin or the like.
(For example, heat resistance of liquid crystal polymer, phenolic resin, etc.
A heat-insulating resin molded product), b. A horizontally long first alternating magnetic field generating means 34 fitted and held between the parallel partition walls 31a and 31a provided along the longitudinal direction at the inner center of the film guide member 31, c. A horizontally elongated guide stay member 35 made of metal, which is disposed above the film guide member 31 to reinforce the film guide member 31 and is fixed to the film guide member 31 with screws or the like, d. The film guide member 31 with the fixing nip portion N inside
First and second temperature sensors S1 and S2, which have heat-sensitive surfaces exposed at the upstream side and the downstream side of the heated material conveyance direction, respectively. A cylindrical fixing film 36 loosely fitted onto the film guide member 31 including the first alternating magnetic field generating means 34, the guide stay member 35, and the first and second temperature sensors S1 and S2.

[0059] First Alternating Magnetic Field Generating Means 34 In the present example, the first alternating magnetic field generating means 34 is a horizontally long core 32 having a high magnetic permeability, and an exciting coil 33 wound around the core 32.
It consists of The high-permeability core 32 is preferably made of a material such as ferrite or permalloy that is used for the core of a transformer, and more preferably ferrite with a low loss at 20 to 100 kHz.

An exciting circuit 50 is connected to the exciting coil 33, and the exciting circuit 50 has a frequency of 20 kHz to 100 kHz.
A high frequency of z can be generated by a switching power supply.

The magnetic flux generated by the high-frequency current applied from the exciting circuit to the exciting coil 33 is guided to the high magnetic permeability core 32 and mainly in the fixing nip portion N.
Act on 6.

[0062] Fixing Film 36 The fixing film 36 has an electromagnetic induction heat generation property. FIG.
(A) is a schematic cross-sectional view showing the layer structure of the fixing film 36 in this example.

That is, the conductive layer 36 made of a metal film or the like as an electromagnetic induction heating layer which is a base layer of the fixing film 36.
It is a film having a three-layer laminated structure of a, an elastic layer 36a provided on the surface side thereof, and a release layer 36c further provided on the surface side thereof. The conductive layer 36a side is the inner surface side of the cylindrical fixing film 36, and the release layer 36c side is the outer surface side.

The magnetic flux a of the alternating magnetic field generated by the alternating magnetic field generating means 34 is an eddy current b in the conductive layer 36a of the fixing film 36.
Generate. Joule heat is generated by the eddy current b and the specific resistance of the conductive layer 36a. The generated heat is elastic layer 3
6b. The recording material nipped and conveyed in the pressure contact nip portion N is heated via the release layer.

The temperature of the fixing film 36 is disposed so that the heat sensitive surface is exposed outside at the upstream side position and the downstream side position of the film guide member 31 in the conveying direction of the heated material with the fixing nip portion N in the middle. First and second temperature sensors S1 and S
2 and the detected temperature information T1 and T2 is taken into the control circuit 51 and the temperature control described later is performed.

A. Conductive Layer 36a The conductive layer 36a serving as the electromagnetic induction heating layer is preferably made of a ferromagnetic metal such as nickel, iron, ferromagnetic SUS, or nickel-cobalt alloy.

Although a non-magnetic metal may be used, a metal such as nickel, iron, magnetic stainless steel, cobalt-nickel alloy, etc., which absorbs magnetic flux is more preferable.

The thickness is preferably thicker than the skin depth expressed by the following equation and 200 μm or less.

The skin depth σ [m] is the frequency f of the exciting circuit.
[Hz], magnetic permeability μ, and specific resistance ρ [Ωm] are expressed as σ = 503 × (ρ / fμ) ^1/2 .

This shows the depth of absorption of electromagnetic waves used for electromagnetic induction. At deeper points, the intensity of electromagnetic waves is 1 / e or less, and conversely, most of the energy reaches this depth. Is absorbed by (Fig. 7).

The conductive layer 36a as the electromagnetic induction heating layer preferably has a thickness of 1 to 100 μm. If the thickness of the conductive layer 36a is less than 1 μm, most of the electromagnetic energy cannot be absorbed, resulting in poor efficiency. In addition, the thickness is 1
If it exceeds 00 μm, the rigidity becomes too high and the flexibility becomes poor, which is not practical for use as a rotary fixing film. Therefore, the thickness of the conductive layer 36a is 1 to 100 μm.
m is preferred.

B. Elastic Layer 36b The elastic layer 36b is made of silicone rubber, fluororubber, fluorosilicone rubber or the like, which has good heat resistance and good thermal conductivity.

The thickness of the elastic layer 36b is preferably 10 to 500 μm. This is the thickness required to guarantee fixed image quality. That is, when printing a color image, a solid image is formed over a large area on the recording material P, especially for a photographic image. In this case, the heating surface of the fixing film 36 (release layer 3
6c) cannot follow, uneven heating occurs, and uneven gloss occurs in the part with a large amount of heat transfer and the part with a small amount of heat transfer (the part with a large amount of heat transfer has a high glossiness, and the part with a low heat transfer amount has a low glossiness). ). If the thickness of the elastic layer 36b is 10 μm or less, the unevenness of the image gloss may occur because the unevenness of the recording material or the toner layer cannot be followed. When the thickness is 1000 μm or more, the thermal resistance of the elastic layer 36b becomes large, which makes it difficult to realize quick start. More preferably, the thickness of the elastic layer 36b is 50 to 500 μm.

If the hardness of the elastic layer 36b is too high, the elastic layer 36b cannot follow the irregularities of the recording material or the toner layer, resulting in uneven image gloss. Therefore, the hardness of the elastic layer is 60 ° (JIS-A) or less, more preferably 45 °.
(JIS-A) The following is preferable.

The thermal conductivity λ of the elastic layer 36b is 6 × 10 ^-4 ~
2 × 10 ⁻³ [cal / cm · sec · deg. ] Is good. Thermal conductivity λ is 6 × 10 ⁻⁴ [cal / cm · sec ·
deg. ], The thermal resistance is large, and the temperature rise in the surface layer of the fixing film becomes slow. The thermal conductivity λ is 2 × 10 ⁻³ [cal / cm · sec · deg. ]
If it is larger than the above range, the hardness becomes too high or the compression set deteriorates. Therefore, the thermal conductivity λ of the elastic layer 36b
Is 6 × 10 ^{−4 to} 2 × 10 ⁻³ [cal / cm · sec · d
eg. ] Is good. More preferably 8 × 10 ^{−4 to} 1.5 ×
10 ⁻³ [cal / cm · sec · deg. ] Is good.

C. Release layer 36c The release layer 36c is made of fluororesin, silicone resin, fluororesin silicone rubber, fluororubber, silicone rubber, P
A material having good releasability and heat resistance such as FA, PTFE, FEP is selected.

The thickness of the release layer 36c is preferably 1 to 100 μm. When the thickness of the release layer 36c is less than 1 μm, there are problems that a part having poor releasability is formed due to coating unevenness of the coating film and durability is insufficient. In addition, the thickness is 100μ
If it exceeds m, there is a problem that heat conduction deteriorates, and especially in the case of a resin-based release layer, the hardness becomes too high, and the effect of the elastic layer 36b disappears.

The constitution of the fixing film 36 having an electromagnetic induction heat generation property is not limited to the above example. In FIG. 5B, a heat insulating layer 36d is further provided on the surface of the fixing film having the above-mentioned structure (a) opposite to the elastic layer 36b of the conductive layer 36a serving as the electromagnetic induction heating layer. The amount of heat generated is conducted to the film guide member 31 side to improve the thermal efficiency.

Further, the fixing film 36 may be a single layer member of the conductive layer 36a as an electromagnetic induction heating layer. Conductive layer 36a
The release layer 36c and the release layer 36c may have a two-layer structure. Conductive layer 36a
May be a metal plating layer or a conductive resin layer obtained by mixing a resin with a metal filler.

C) Pressure Roller 4 The pressure roller 4 is also an electromagnetic induction heat-generating member, and this example has a layered structure as shown in the cross-sectional model view of FIG. That is, a hollow core metal (roller base) 4a such as aluminum, a conductive layer 4b as an electromagnetic induction heating layer, an elastic layer 4c, a release layer 4d, and a hollow core metal 4 which are sequentially laminated on the outer periphery of the core metal 4a.
It comprises a second alternating magnetic field generating means 41 arranged in a, a third temperature sensor S3 such as a thermistor arranged in contact with the outer surface of the roller.

The material of the conductive layer 4b as the electromagnetic induction heating layer may be a non-magnetic metal, but more preferably a ferromagnetic metal such as nickel, iron, magnetic stainless steel, cobalt-nickel alloy or the like which has good absorption of magnetic flux. good.

The material of the elastic layer 4c is silicone rubber, fluororubber, fluorosilicone rubber or the like, which has good heat resistance and good thermal conductivity.

For the release layer 4d, a material having good releasing property and heat resistance such as fluororesin, silicone resin, fluororesin silicone rubber, fluororubber, silicone rubber, PFA, PTFE or FEP is selected.

The second alternating magnetic field generating means 41 arranged in the hollow core metal 4a is composed of a high magnetic permeability core and an exciting coil, and an exciting circuit 52 is connected to the exciting coil. The magnetic flux in the alternating field generated by the application of the high frequency current acts on the conductive layer 4b of the pressure roller 4 to generate the eddy current b. Joule heat is generated by the eddy current b and the specific resistance of the conductive layer 4b, and mainly the surface of the pressure roller 4 is heated.

The temperature state of the pressure roller 4 depends on the temperature of the pressure roller 4.
The temperature information T3 detected by the third temperature sensor S3 that is brought into contact with the surface of the device is taken into the control circuit 51, and the temperature control described later is performed.

D) Temperature Control In the fixing device of the present embodiment, the heat-sensitive surface is located outside at the upstream side position and downstream side position of the film guide member 31 with the fixing nip portion N in the middle. The first and second temperature sensors S1 and S2 are arranged so as to be exposed as described above, and the third temperature sensor S3 is arranged in contact with the surface of the pressure roller 4. . Fixing film 3
6, the inner surface of which is the first and second temperature sensors S1 and S
Rotate while sliding on the heat sensitive surface of 2. In the present embodiment example, the first to third temperature sensors S1, S2 and S3 are all thermistors.

Thus, the first and second temperature sensors S1.
The temperatures T1 and T2 of the fixing film 36 are respectively determined by S2.
Is detected, the temperature T3 of the pressure roller 4 is detected by the third temperature sensor S3, and the detected temperature T3 is input to the control circuit 51.

When the recording material P is fixed, the control circuit 51 performs arithmetic processing on the respective detected temperatures T1, T2, T3 from the first to third temperature sensors S1, S2, S3, Based on the control of the exciting circuit 50 and the exciting circuit 52 to control the current or voltage applied to the first and second alternating magnetic field generating means 34 and 41, the heat generation amounts of the fixing film 36 and the pressure roller 4 are controlled. By controlling Q1 and Q2, the temperature of the device is controlled in a predetermined manner.

First to third temperature sensors S1, S2, S
By using a chip thermistor or the like having good thermal responsiveness as the thermistor 3, the heat generation amount of the fixing film 36 having a small thickness and a small heat capacity and the pressure roller can be quickly and accurately controlled. Further, even when the heat generation amount necessary for fixing changes due to the type of the recording material P, the density change of the toner image on the recording material, the fluctuation of the surrounding environment, etc., the change in the required heat generation amount is detected and the temperature is controlled. be able to.

As a result, it is possible to always obtain a fixed image having a uniform fixing property and gloss regardless of the type of the recording material, the density of the toner image, the environmental change and the like.

According to the apparatus of this example, the fixing film 36, which is a heat source, and the recording material P are very close (close contact).
Therefore, it can be considered that the fixing film temperature = the temperature of the recording material.
Therefore, as in this example, the temperature difference between the temperature sensors S1 and S2 is small because the heat capacity of the fixing film 36 is small, so that the recording material P
Is considered to be the amount of heat taken to fix the toner by passing through the fixing nip portion N. As an example of temperature control, the temperature required for fixing is set to 180 ° C. (temperature sensor S2). At the time of fixing, heat is taken by the recording material P and the temperature sensor S2> the temperature sensor S1.
The current or voltage is changed so that the temperature becomes 0 ° C.

With respect to the temperature sensor S3, since the heat capacity of the pressure roller 4 is much larger than that of the fixing film 36, the temperature sensor S3 detects the temperature for each rotation of the pressure roller and the temperature control is performed.

In a normal roller fixing using a halogen heater or the like, since the heat source (heater) and the recording material are far from each other and the heat capacity of the fixing roller is large, the surface temperature of the fixing roller is large. Even if the heat generation amount of the heater is detected by detecting the temperature, it takes time to reach the desired temperature, and it is difficult to perform accurate temperature control.

E) Material of device structure Unfixed toner on recording material P Since only the fixing film and the pressure roller in the fixing nip portion N are required for heat generation when fixing an image, the first and second alternating magnetic fields are used. When the guide stay member 35, the device lower frame 1, the device upper frame 2 and the like generate heat due to the influence of the magnetic flux generated from the generating means 34 and 41, the power consumption of the entire device becomes large and the efficiency deteriorates, and it is also disadvantageous for quick start. Is.

Therefore, in the present embodiment, all the metallic components, which are the components of the apparatus, other than the fixing film 36 and the conductive layers 36a and 4b as the electromagnetic induction heating layers of the pressure roller 4 are made of Al. And non-magnetic metal such as non-magnetic SUS.

F) Calorific Value of Fixing Film and Pressure Roller In the case of color image fixing, the necessary heat capacity is larger during fixing than in monochrome image fixing in order to form four color toner images on the recording material P. However, in the case of fixing a color image, if a large heat capacity is applied from the toner image surface side, the gloss of the fixed image becomes high, and it is pointed out that the light of a fluorescent lamp or the like is reflected and is difficult for some users to see.

In this embodiment, the heat capacity required for fixing a color image is set so that the heat generation amount on the pressure roller 4 side is larger than the heat generation amount on the fixing film 36 side, so that the gloss is suppressed to a low level. I am trying to get a color fixed image.

However, in the case of double-sided printing, the amount of heat generated on the side of the fixing film 36 is made larger than the amount of heat generated on the side of the pressure roller 4 in order not to disturb the fixed image on the first side. As a result, a clear color-fixed image can be obtained even in double-sided printing.

G) Width-wise Relational Dimension between Device Constituent Members A problem with the film-type electromagnetic induction heating device using an electromagnetic induction heat-generating film such as a thin metal film of the present invention is as follows: <1> Meandering of thin film <2> Damage to the surface of the pressure member due to the edge of the metal film <3> Temperature rise of the film and the edge of the pressure member due to the magnetic flux concentration at the end of the exciting coil as the alternating magnetic field generating means To be

In the present embodiment, in view of the above problems, the fixing film 36 is driven by a tensionless pressure roller to reduce the meandering force to prevent the film edge damage of <1>. There is.

That is, the cylindrical fixing film 36 is loosely fitted onto the film guide member 31, and the fixing nip portion N
In the device configuration in which the fixing film 36 is rotated by rotationally driving the pressure roller 4 on which the pressure roller 4 is formed (pressure roller driving method), tension is applied to the film portion other than the fixing nip portion N and its vicinity when the fixing film rotates. Without applying (tensionless), when the fixing film is rotated, the displacement force of the film along the length of the film guide member 31 is small. Therefore, although a means for restricting the shift of the film is omitted in the drawing, a simple means structure such as a simple flange member for receiving the film edge is sufficient, and damage to the film edge is also prevented.

Further, as shown in the dimensional relationship diagram of FIG. 8 in the direction orthogonal to the sheet passing direction with respect to the apparatus, the maximum size width WP of the recording material P that can be used for sheet passing through the apparatus and the exciting coil for generating the alternating magnetic field. By setting the relationship between the width WC, the fixing film width WF, and the pressure member width WK as WP <WK <WF <WC, the problems <2> and <3> are solved.
It is possible to realize a film type electromagnetic induction heating device that heats the fixing film and the pressing member by the alternating magnetic field.

(3) Others 1) The alternating magnetic field generating means includes a conductive layer 36a as an electromagnetic induction heating layer of the fixing film 36 and a conductive layer 4b as an electromagnetic induction heating layer of the pressure roller 4 at least in the fixing nip portion N. It is also possible to use a common one that both generate heat.

2) The temperature sensor for detecting the temperature of the film for controlling the temperature is arranged such that the fixing nip portion N is located inside and the first and second positions of the film guide member 31 in the upstream and downstream positions of the heated material conveying direction. Any one of the second temperature sensors S1 and S2 may be used. Further, any one of them and two third temperature sensors S3 for detecting the pressure roller temperature may be provided.

The first and / or second temperature sensors S1 and S2 for detecting the film temperature may be arranged on the outer surface side of the fixing film 36, which is the pressure roller side.

3) A metal is not used as the base material for the conductive layer as the electromagnetic induction heating layer in the fixing film or the pressure roller,
A heat-generating layer may be formed by stacking a resin layer in which a material such as a metal filler is mixed on a resin film having heat resistance and strength such as polyimide.

4) In the fixing device as the heating device of the embodiment, the cylindrical film is driven by the pressure roller (pressure roller driving system), but the endless film 36 is formed as shown in FIG. A device configuration may be adopted in which tension is applied by the tension roller 39 to drive the film 36 by the drive roller 38. Also, as shown in (b), the film 36 with the end wound into a roll is fed from the feeding shaft 40 side to the winding shaft 41 side. It is also possible to adopt a film winding traveling type device configuration in which the film is wound and traveling at a predetermined speed.

5) In the fixing device of the embodiment, since the toner containing the low-softening substance is used in the toner, the fixing film and the pressure roller are not provided with an oil application mechanism for preventing the offset, but the low-softening substance is used. When a toner not containing is used, an oil applying mechanism may be provided.

6) A cooling unit may be provided on the downstream side of the fixing nip portion N in the recording material conveying direction to cool and separate the recording material from the fixing film. Also, when a toner containing a low softening substance is used, oil application or cooling separation may be performed.

7) Although the four-color image forming apparatus has been described in the embodiment, it may be a monochrome or one-pass multi-color image forming apparatus.

8) The heating device of the present invention is not limited to the image heating and fixing device of the embodiment, but is a device for heating a recording material carrying an image to modify the surface properties such as gloss, and an assumed image heating device. In addition, it can be widely used as a heating / drying device for a material to be heated, a heating laminating device, and the like, as a device / apparatus for heat-treating a material to be heated.

[0112]

As described above, according to the present invention, in the heating device of the electromagnetic heating system, the film as the electromagnetic induction heating member and the pressing member are quickly heated in a short time, and the calorific value is accurately measured. It can be controlled, and as a heat fixing device for an image, it does not cause image deterioration such as uneven gloss when fixing a color toner image, assures good fixability while maintaining high image quality, and realizes a quick start. it can. Further, not only a clear fixed image can be obtained at the time of image heat fixing of the first and second sides in the double-sided print mode, but also the printing speed can be increased. Further, the heat capacity of the member relating to fixing can be designed to be small, and energy saving can be realized.

That is, the electromagnetic heating type heating device has a quick start property, is energy-saving, has good temperature stability and temperature controllability, and is sufficiently compatible with a high-speed model as a heat fixing device and a color image forming device. It is possible to obtain a heating device made possible, and the intended purpose is often achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of an image forming apparatus.

FIG. 2 is an external perspective view of a fixing device.

FIG. 3 is an exploded perspective view of a fixing device.

FIG. 4 is an enlarged cross-sectional model view of the fixing device.

5A and 5B are schematic diagrams of the layer structure of a fixing film, respectively.

FIG. 6 is a layer structure model diagram of a pressure roller.

FIG. 7 is a graph showing electromagnetic wave intensity and penetration depth.

FIG. 8 is a width dimension relationship diagram of a recording material, an excitation coil width, a fixing film, and a pressing member.

9 (a) and 9 (b) are schematic views of another embodiment of the film-type electromagnetic induction heating device.

[Explanation of symbols]

101 Photoreceptor Drum 102 Charging Device 110 Laser Scanner 104 Developing Device 105 Transfer Body Drum 106 Transfer Roller 107/108 Cleaner 100 Fixing Device 1.2 Fixing Device Lower and Upper Frame 3 Fixing Film Unit 4 Pressing Roller N Pressure Nip Part 34/41 First and second alternating magnetic field generating means (excitation coil) 36 Fixing film 36a / 36b / 36c / 36d Conductive layer / elastic layer /
Release layer / heat insulating layer S1, S2, S3 First to third temperature sensors

Claims (9)

[Claims] 1. An electromagnetic induction heat-generating film and an electromagnetic induction heat-generating pressure member, which are brought into pressure contact with each other, and at least one alternating magnetic field generating means for introducing an alternating magnetic field into the film and the pressure member, and the film. A heating device that heats and heats the material to be heated by the film and the pressure member that are heated by electromagnetic induction by the alternating magnetic field of the alternating magnetic field generating means by sandwiching and transporting the material to be heated in the pressure contact nip part of the pressure member. The temperature sensor for is disposed on at least one of the upstream side and the downstream side in the material-to-be-heated conveying direction of the pressure contact nip portion between the film and the pressure member, and detects the temperature of the film. 2. The heating device according to claim 1, wherein the temperature sensors for controlling temperature control are arranged on the upstream side and the downstream side of the pressure-contact nip portion between the film and the pressing member in the heated material conveying direction, A heating device characterized in that the amount of heat generated by the film and the pressing member is controlled by controlling the current or voltage applied to the alternating magnetic field generating means according to the difference between the temperatures detected by the two temperature sensors. 3. An electromagnetic induction heat-generating film and an electromagnetic induction heat-generating pressure member, which are brought into pressure contact with each other, and at least one alternating magnetic field generating means for applying an alternating magnetic field to the film and the pressure member. A heating device that heats and heats the material to be heated by the film and the pressure member that are heated by electromagnetic induction by the alternating magnetic field of the alternating magnetic field generating means by sandwiching and transporting the material to be heated in the pressure contact nip part of the pressure member. The temperature sensor for is arranged on the pressure member surface and at least one of the upstream side and the downstream side of the heated nip portion of the film and the pressure member in the conveying direction of the material to be heated. A heating device characterized by detecting. 4. The heating device according to claim 3, wherein the temperature detected by each temperature sensor is arithmetically processed and applied to at least one of the alternating magnetic field generating means of the film side and the pressing member side. A heating device in which the amount of heat generated by the film and the pressing member is controlled by controlling the current or voltage. 5. The heating device according to claim 1, wherein the temperature sensor for detecting the temperature of the film is arranged on the inner surface side of the film opposite to the pressure member side of the film. A heating device characterized in that 6. The heating device according to claim 1, wherein the metal is a device constituent member other than the film and the pressing member, and is affected by the alternating magnetic field generated by the alternating magnetic field generating means. The heating device, wherein the manufacturing member is a non-magnetic material. 7. The heating device according to claim 1, wherein the material to be heated is a recording material to be image-heated and fixed, and an unfixed image is formed and carried on one surface of the recording material. Then, the one surface side is introduced into the apparatus with the film side to perform the image heat fixing of the one surface, and the unfixed image is formed and carried on the two surfaces of the recording material, and the two surface side is the film side. In the case of re-introducing into the apparatus and carrying out the image heating and fixing of the two surfaces, the heat generation amount Q1 on the film side and the heat generation amount Q2 on the pressure member side during the image heat fixing of the first surface of the recording material are A heating device characterized in that Q1 <Q2 and Q1> Q2 at the time of image heating and fixing of the second surface of the recording material. 8. The heating device according to claim 1, wherein the maximum size width WP of the material to be heated and the coil width WC for generating the alternating magnetic field of the alternating magnetic field generating means,
The heating device characterized in that the relationship between the film width WF and the pressing member width WK is WP <WK <WF <WC. 9. An image forming apparatus having an image forming means for forming and carrying an unfixed image on a recording material, and a heating fixing means for heating and fixing the unfixed image on the recording material, wherein the heating and fixing means comprises: 9. An image forming apparatus, which is the heating device according to any one of items 1 to 8.