JP2002221219A - Heating device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device provided with an enhanced heated-material heat-speed property for a thermal roller-type heating device and an excellent on-demand property for a film-heat type heating device, and also provided with a power-saving property, capable of conducting uniform heat treatment to a heated material, and performing uniform heating to a recoding material irrespective of the thickness of a toner, with no exertion of influences of a protrusion of a heater and film, in an image-heating device such as a fixing device. SOLUTION: The heating device comprising a rotating heating roller 15, an externally heating means 20 for heating the heating roller from the outside of the roller, and a pressurizing rotating body 19 for forming the heating roller and a nipping section N. Also, the device nips and carries the heated material 11 with the nipping section N and heats the heated material 11 with the heat of the heating roller 15 of which the roller base body 15a is made of a ceramic porous material. At least an elastic-material layer 15b is formed on the roller base body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus of a type in which a sheet-like material to be heated is passed through a press-contact nip portion of a heating means and a pressure means and nipped and conveyed to heat the material to be heated. The present invention relates to an image forming apparatus including a heating device as an image fixing device for heating.

Here, the heating of the material to be heated includes, for example, a heating and fixing process of an unfixed image formed and supported on a recording material by a transfer system or a direct system, an image heating process of temporarily attaching, Examples include an image heating process for heating a recording material carrying an image to improve the surface properties such as gloss, a heating drying process for a sheet-like material to be heated, a heat laminating process, and a hot pressing process for removing wrinkles.

[0003]

2. Description of the Related Art A heat fixing device in an image forming apparatus such as an electrophotographic copying machine or a printer will be described as an example.

For example, in a transfer-type electrophotographic process, an unfixed image electrostatically transferred from a photoreceptor to a transfer material which is a sheet-like recording material such as paper or an OHT sheet is electrically weakly coupled. In order to make this a permanent fixed image, it is necessary to further strongly bond to the transfer material. Generally, an unfixed image is formed by toner, and this toner is characterized in that it is semi-melted when heat is applied. Utilizing this feature, a heat fixing method is known as a method for forming a permanent image.

The heat fixing method includes a radiant flash fixing method and an oven fixing method using only heat energy, a heat roller method using heat energy and pressure, and a film heating method.

At present, a heat roller method using a heat pressure method and a film heating method are mainly used from the viewpoint of high speed and safety.

(A) Heat Roller System FIG. 8 is a schematic diagram of a heat roller system heating device (fixing device). Reference numeral 8 denotes a heat roller (heating roller, hereinafter referred to as a fixing roller) as a heating member. Reference numeral 9 denotes an elastic pressure roller as a pressing member. Are pressed against each other with a predetermined pressing force against the elasticity of the nip portion N to form a nip portion N which is a heating portion (fixing portion).

The fixing roller 8 and the pressure roller 9 rotate at a predetermined peripheral speed in the direction of the arrow.

A heater 7 such as a halogen lamp is provided inside the fixing roller 8, and the fixing roller 8 is heated from the inside by the heat generated by the heater 7, so that the surface temperature of the fixing roller 8 reaches a predetermined fixing temperature. The power supply to the heater 7 is controlled by a temperature control circuit (not shown) including the fixing roller temperature detection element 4 so as to be maintained.

When the fixing roller 8 and the pressure roller 9 are driven to rotate, and the temperature of the fixing roller 8 rises to a predetermined fixing temperature and is regulated, both rollers 8.
The recording material (transfer material) 11 carrying the unfixed toner image 10 is introduced into the nip portion N of the printer 9 and the nip portion N is nipped and conveyed, so that the recording material 11 of the unfixed toner image 10 is fixed by the fixing roller 8. Is heat-fixed. In the nip portion N, the toner forming the unfixed image 10 is partially melted, and penetrates into irregularities on the surface of the recording material by being pressed.

(B) Film heating system A heating device of the film heating system is disclosed in JP-A-63-31318.
No. 2, JP-A-2-1577878, JP-A-4-15778
No. 44075-44083 have been proposed.

FIG. 9 is a schematic view of a main part of a film heating type heating device (fixing device). Numeral 12 denotes a heating element, which is a so-called ceramic heater which has a low heat capacity and rapidly rises in temperature. The heater 12 is fixedly supported by a heat insulating member 14. Reference numeral 13 denotes a heat-resistant film (hereinafter, referred to as a fixing film). 9 is an elastic pressure roller. The heater 12 and the pressure roller 9 are pressed against each other with a predetermined pressing force against the elasticity of the pressure roller 9 with the fixing film 13 interposed therebetween to form a nip portion N which is a heating portion (fixing portion).

The fixing film 13 is driven by a driving means (not shown) or by the rotation of the pressure roller 9 to form a nip portion N.
At the same time, the heater 12 slides while closely contacting the surface of the heater 12.

The heater 12 quickly rises in temperature when power is supplied to a heating resistor layer (not shown).
Is maintained by a temperature control circuit (not shown) including the heater temperature detecting element 4 so that the temperature of the heater 12 is maintained at a predetermined fixing temperature.
Is controlled.

When the fixing film 13 is moved and the temperature of the heater 12 rises to a predetermined fixing temperature and the temperature is controlled, an undetermined state is established between the fixing film 13 in the nip N and the pressure roller 9. Toner image 10
Is transferred, the unfixed toner image carrying surface is brought into close contact with the fixing film 13 surface, and the nip portion N is conveyed together with the fixing film 13. In the process of nipping and transporting the nip N, the fixing film 13
The unfixed toner image 10 is heated and fixed to the transfer material 11 by the heat from the heater 12 through the heater.

Since the fixing film 13 is thin, has a small heat capacity, and has good thermal response, the thermal response of the heater 12 can be reflected in the nip portion N as it is.
Therefore, the time required to reach the fixing temperature is shorter than when the heater is turned on (on-demand), and power saving is realized accordingly.

Further, in order to perform the fixing speed realized by the heat roller system by this system, it is only necessary to reduce the low heat capacity of each part and increase the thermal response.

[0018]

In the heat roller type fixing device, since the heat capacity of the fixing roller 8 is large, the time required for the nip portion N to reach a predetermined fixing temperature becomes long. Further, if the fixing roller 8 is always kept at a high temperature in order to shorten the initial output time, there is a problem that much electric power is consumed.

What solves these problems is a film heating type fixing device. Just as a further improvement,
Due to the decrease in the adhesion to the toner image due to the high rigidity of the fixing film 13, even a slight protrusion generated on the heater 12 or the fixing film 13 may cause a spot-like matte spot or streak on the image. When multiple types of toner are superimposed and fixed as in a color image, color misregistration may occur, or insufficient color mixing may occur due to insufficient melting, or conversely, only the upper layer toner may be used. It is demanded that there be no cases of offset due to melting.

Accordingly, the present invention combines the advantages of the heating device of the heat roller type with the advantages of the heating device of the film heating type, that is, the heating of the material to be heated realized by the heating device of the heating roller type. (Fixing) Provided is a heating device having an apparatus configuration that has both the speed property and the like, the on-demand property and the power saving property of a film heating type heating apparatus, and can perform uniform heating processing of a material to be heated. The purpose is to:

In an image heating device such as a fixing device, a heating device capable of uniformly heating a recording material regardless of the thickness of the toner and without being affected by a heater or a projection of a film. And an image forming apparatus provided with the heating device as an image heating and fixing device.

[0022]

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

(1) A heating roller which rotates, an external heating means for heating the heating roller from outside the roller, and a pressure rotating body which forms a nip portion with the heating roller, wherein the nip portion A heating device for nipping and transporting the material to be heated and heating the material to be heated with the heat of the roller for heating, wherein the roller for heating is such that the roller base is a ceramic porous body,
A heating device comprising at least an elastic layer formed on the roller base.

(2) An elastic layer and a releasable layer are further formed on the roller base (1).
A heating device according to claim 1.

(3) The heating device according to (1) or (2), wherein the pressing rotary member is an elastic roller.

(4) The external heating means has a fixedly supported heating element and a film sliding on the heating element, and the heating element is pressed against the outer surface of the heating roller with the film interposed therebetween. The heating device according to any one of (1) to (3), wherein an outer surface of the heating roller is heated by heat of the heating body via the film.

(5) The material to be heated is a recording material carrying an image, and the recording material is nipped and conveyed in a nip portion, and the image on the recording material is heated by the heat of a heating roller. The heating device according to any one of (1) to (4).

(6) An image forming apparatus having an image forming means for forming and carrying an unfixed toner image on a recording material and a fixing means for heating and fixing the unfixed toner image on the recording material onto the recording material. An image forming apparatus, wherein the fixing unit is the heating device according to any one of (1) to (5).

<Operation> A porous ceramic body is remarkably excellent in heat insulation. This ceramic porous body is used as a roller base, and at least an elastic layer is provided on the outer peripheral surface of the roller base to form a heating roller, and the heating roller is heated from the outside of the roller by an external heating configuration. The heating roller surface can be quickly heated to a required temperature and started up by storing the necessary amount of heat in the elastic layer which is a surface layer, and the heating device is provided with on-demand and low-power characteristics. Becomes possible.

The ceramic porous body is rigid. The ceramic porous body is used as a roller base, and at least an elastic layer is provided on the outer peripheral surface of the roller base to form a heating roller.
Heating (fixing) of the material to be heated is the same as in the case of the heat roller method, because the pressure applied to the nip between the pressure roller and the rotating body can be increased sufficiently without causing distortion in the heating roller.
Speed property and the like can be provided, and uniform heating of the material to be heated can be performed.

In an image heating device such as a fixing device, uniform heating can be performed on a recording material regardless of the thickness of the toner and without being affected by a protrusion of a heater or a film.

That is, since the nip portion for nipping and conveying the recording material and heating it is formed of a heating roller having an elastic layer and a rotating body for pressing, the nip portion is generated in a heater or a fixing film in a film heating type apparatus. The phenomenon that dot-like matted spots or streaks are formed on the image by a slight protrusion is avoided, and when a plurality of types of toners are overlaid and fixed as in a color image, a color shift occurs, or It is also possible to avoid a phenomenon in which the color mixture is insufficient due to insufficient melting, and conversely, only the toner in the upper layer is melted and offset.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 (1) Example of Image Forming Apparatus FIG. 1 is a schematic structural model diagram of an image forming apparatus in the present embodiment. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process.

Reference numeral 101 denotes a photosensitive drum as an image carrier, and a photosensitive material such as OPC, amorphous Se, amorphous Si or the like is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 101 is driven to rotate at a predetermined peripheral speed (process speed) in a clockwise direction indicated by an arrow.

Charging Step: First, the surface of the rotating photosensitive drum 101 is uniformly charged to a predetermined polarity and potential by a charging roller 102 to which a predetermined charging bias voltage is applied as a charging device.

Exposure step: Next, the rotating photosensitive drum 101
The laser beam scanner 103 performs scanning exposure with the laser beam L whose ON / OFF is controlled in accordance with image information on the charging processing surface of the laser beam. As a result, an electrostatic latent image corresponding to the scanning exposure pattern is formed on the surface of the rotating photosensitive drum 101.

Developing step: The electrostatic latent image is developed
Is developed as a toner image. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used.

Transfer step: The toner image on the surface of the rotating photosensitive drum 101 is transferred onto a recording material (transfer material) 11 at a transfer nip portion where a transfer roller 105 serving as a transfer device and the photosensitive drum 101 are in contact with each other. Is done.

The transfer roller 105 is brought into contact with the photosensitive drum 101 with a predetermined pressure, and rotates in the forward direction of the photosensitive drum 101 at a peripheral speed substantially equal to the peripheral speed of the photosensitive drum 101. Further, a predetermined transfer bias voltage is applied. The recording material 11 is fed to the transfer nip portion at a predetermined control timing from a paper feeding mechanism (not shown), and the photosensitive drum 10
The transfer nip portion formed by the transfer roller 1 and the transfer roller 105 is nipped and conveyed by a constant pressing force.

Here, the leading end of the recording material conveyed from the paper feeding mechanism to the transfer nip is detected by a sensor so that the image forming position of the toner image on the photosensitive drum 101 and the starting position of the leading end of the recording material coincide. Detection is performed at 106, and the timing is adjusted (registration).

Fixing step: The recording material P to which the toner image has been transferred at the transfer nip is separated from the surface of the rotating photosensitive drum 11 and is conveyed to a fixing device 108 as a heating device.
The toner image is fixed by heating as a permanent image.

Cleaning step: On the other hand, photosensitive drum 1
The transfer residual toner remaining on the surface of the photosensitive drum 101 is removed by the cleaning device 107. The photoreceptor drum 101 is repeatedly provided for image formation.

(2) Fixing Device 108 FIG. 2 is an enlarged cross-sectional model view of the fixing device 108. Fifteen
Denotes a heating roller (fixing roller), 19 denotes a pressure roller that forms a nip portion N with the heating roller 15, and 20 denotes a heating roller 1.
An external heating means for heating 5 from outside the roller.

A) Heating Roller 15 The heating roller 15 has a roller base (base) 15a made of a ceramic porous body, and a silicone rubber layer 15b as an elastic layer formed on the outer peripheral surface of the roller base 15a. Further, a configuration is also provided in which a fluororubber layer 15c is formed on the outer peripheral surface as a release layer (surface layer).

More specifically, as the roller base 15a, a ceramic porous body made of glass and having an outer diameter of about 24 mm, an inner diameter of about 8 mm, a bulk density of 0.55 g / cm 3, and a porosity of 79% (Nichias Corporation) An outer peripheral surface of the roller base 15a is subjected to a primer treatment using a brand name of Cellar A (manufactured by a company) to obtain a liquid silicone rubber (DY35-DY).
561A / B: manufactured by Dow Corning Toray Silicone Co., Ltd.)
Is coated by a blade coating method, and is heated and cured at 130 ° C. for 30 minutes, and then subjected to secondary vulcanization for 4 hours in an oven set at 200 ° C., to have a thickness of 0.5 mm as an elastic layer.
Of the silicone rubber layer 15b was formed.

After subjecting the surface of the silicone rubber layer 15b to a predetermined primer treatment (GLP103SR: Daikin Industries, Ltd.), a fluororubber latex (GLS21
3: Daikin Industries, Ltd.) was spray-coated to a dry thickness of about 30 μm, dried at 70 ° C., and baked in an oven at a set temperature of 310 ° C. for 30 minutes to form a surface layer. As a result, the fluororesin in the fluororubber latex forms a surface layer having a thickness of about 1 to 3 μm, and a good release layer 15 is formed.
c could be formed.

Next, an aluminum core metal 15d having a diameter of 8 mm is fixed to the inner diameter portion of the roller base 15a with an epoxy resin-based adhesive, and a silicone rubber heat insulating roller having a rubber length of 230 mm and an outer diameter of 25 mm as the heating roller 15 is prepared. did.

By adopting such a configuration, the heat conductivity of the heating roller 15 as a roller is 0.05 to 0.5 mm.
A roll having a high heat insulating property of 1 W / m · K can be obtained.

This shows that the heat insulating property is remarkably improved as compared with 0.3 W / m · K in the case of ordinary silicone rubber solid. In addition, in the thermal conductivity of a conventional sponge, the lower limit is limited to prevent compression set, and the limit is 0.1 to 0.2 W / m · K. In the case of sponge, in order to increase the heat insulating property, if the foaming rate is further increased, the hardness will decrease and the pressure will not be easily applied, or there is a drawback that permanent set will occur,
Since a highly rigid ceramic is used for the roller base 15a, no distortion occurs. In addition, since the surface layer has the rubber layer 15b having the minimum heat capacity necessary for storing heat, the structure is more suitable for transferring the externally heated heat to the object to be heated.

The heating roller 15 is disposed so that both ends of the cored bar 15d are rotatably held between the side plates of the apparatus via bearings, and is driven in a clockwise direction indicated by an arrow by a drive system (not shown). It is driven to rotate at the peripheral speed.

The ceramic porous body which can be used in the present invention makes use of the elasticity of a thin rubber elastic layer among ceramic materials which are excellent in thermal deterioration and aging and have high pressing force on a material to be heated (recording material). It is porous.
Under the above conditions, the material is capable of obtaining a uniform pressure / fixing property irrespective of the unevenness of the material to be heated (recording material).

The practical range of the physical properties of the ceramic porous body usable in the present invention is as follows: bulk density: 0.35 to 1.80 g / cm
^2. Porosity: 30-90%, Thermal conductivity: 0.1 W / m · K or less.

As an example of the method for producing a ceramic porous body, clay and water are added to ceramic fibers, kneaded, molded, dried and cured. During the drying and curing process, a porosity is formed after the water evaporates. By changing the ratio of the ceramic fiber and the clay, the distribution amount of the fine voids is easily adjusted, and the porosity of about 30 to 70% (however, porosity = [1-bulk specific gravity / true specific gravity] x 100) is obtained. Obtainable.

Aluminosilicate fibers, alumina fibers and the like can be used as ceramic fibers as raw materials, and Gairome clay, Kibushi clay, kaolin, bentonite and the like can be used as clays. In order to obtain a product having fine voids having a uniform size and distribution, it is desirable to use a high quality ceramic fiber and a clay having a uniform particle size. Since it is difficult to produce a cylindrical molded body having the required physical properties using only ceramic fibers and clay, an inorganic binder and a molding aid are appropriately added thereto. Examples of suitable inorganic binders include colloidal silica, alumina sol and the like, and as a molding aid, methyl cellulose, carboxymethyl cellulose and the like can be used.

B) Pressure Roller 19 The pressure roller 19 is composed of a core 19a and a solid silicone rubber layer 19 formed concentrically and integrally around the core in the form of a roller.
b is a heat-resistant and elastic roller.

The pressure roller 19 is arranged below the heating roller 15 in parallel with the heating roller 15 so that both ends of the cored bar 19a are rotatably supported by bearings. A nip portion N having a predetermined width is formed by pressing against the lower surface of the heating roller 15 with a predetermined pressing force against the elasticity of the heating roller 19b. In the present embodiment, the pressure roller 19 is pressed against the heating roller 15 with a total pressure of 200 N to form a nip portion N having a width of about 6 mm.

The pressure roller 19 rotates in the forward direction in the rotation direction of the heating roller 15 in conjunction with the rotation of the heating roller 15, and cooperates with the heating roller 15 when the recording material 11 is introduced into the nip N. The recording medium 11 is pinched and conveyed by the operation. In this embodiment, the conveyance speed of the recording material 11 is 122 mm / sec.

C) External Heating Means 20 In this embodiment, the external heating means 20 for heating the heating roller 15 from outside the roller is a film heating type heater unit (heat supply unit).

[0059] A film 16 is an endless (cylindrical) heat-resistant film having an outer diameter of 24 mm and a thickness of 60 μm, a ceramic heater 17 as a heating element, and a film guide member 18 having a trough semicircular arc cross section. The heater 17 is a film guide member 1
8 is fitted and fixedly supported in a fitting groove formed in the longitudinal direction of the film guide member at a substantially central portion on the outer surface side. The endless film 16 is loosely fitted to a film guide member 18 including a heater 17.

The film 16 has a film thickness of 10 to reduce the heat capacity and improve the quick start property.
0 μm or less, preferably 50 μm or less 20 μm or more heat-resistant single layer of PTFE, PFA, FEP, or polyimide, polyamideimide, PEEK, PES, P
A composite layer film in which the outer peripheral surface of PS or the like is coated with PTFE, PFA, FEP, or the like can be used.

[0061] Film Guide Member The film guide member 18 is a heat-resistant and rigid member, for example, a member obtained by adding glass to a heat-resistant resin such as PPS, a liquid crystal polymer, or a phenol resin to increase the strength. These resins are used by being injected into a mold for molding.

[0062] Heater Ceramic heater 1 as a heating element in the present embodiment
Reference numeral 7 denotes a heater having a resistance value of 18Ω and a width of 8.75 mm and 270 mm. FIG. 3 is a configuration diagram of the heater,
(A) is a partially cutaway plan view of the heater surface side,
(B) is a plan view of the heater back side, and (c) is (b).
It is an expanded cross-sectional model along the cc line of the figure.

The heater 17 has a thickness of 0.6 to 2.0 mm and a width of 8.75 as a heater substrate (heat conductive substrate).
mm, 270 mm ceramic substrate a made of alumina or the like, and silver palladium (Ag / P
d) or a heating resistor layer b of a resistance material such as ruthenium oxide.
b is formed by screen printing, and a thickness of 40
A protective layer (overcoat layer) c of glass or the like having a thickness of about 100 μm is formed, and the surface of the heater (the side on which the heating resistor layer b and the protective layer c are formed) is exposed to the outside so that the film guide member 18 is formed. Is fixedly supported.

In the heater 17 of this embodiment, two parallel heating resistor layers bb are formed on the surface side of the substrate a along the longitudinal direction of the board, and the heating resistor layers bb on the same side of the heating resistor layers bb are formed. One end side is provided with first and second current-carrying electrodes (input terminals) f and g which are electrically connected to each other via the circuit patterns d and e, respectively. The other end sides of the heating resistor layers b are electrically connected to each other via a current-carrying pattern h. Then, the substrate surface is first and second conducting electrodes f ·
g is exposed, and the heating resistor layers bb
E, energization pattern h is covered with a protective layer c.

A thermistor 4 such as an NTC thermistor, which is bonded, pressed or integrally formed with a heat conductive silicone rubber adhesive or the like, is provided on the back side of the heater (the back side of the substrate).

The first and second current-carrying electrodes f of the heater 17
The current is supplied from the heater drive circuit 110 through a power supply connector (not shown) between the g and the heating resistor layer b.
b generates heat, and the temperature of the heater 17 rises quickly as a whole. The heater-temperature is monitored by the thermistor 4,
The monitor temperature information is input to the control circuit (microcomputer) 111. The control circuit 111 is a thermistor 4
The heater drive circuit 110 is controlled to maintain the heater temperature at a predetermined control temperature (for example, 170 ° C. to 200 ° C.) based on the monitor temperature information of the commercial AC power supply (AC 1).
00V) From 112 to the heating resistor layers bb of the heater 17
To control the amount of electricity to That is, the control circuit 111 controls the heater-drive circuit 110 so that the detection output of the thermistor 4 becomes a predetermined constant value, and controls the energization to the heating resistor layers b. Based on PI (proportional / integral) control, the amount of current (supplied power) is finely supplied by well-known means such as phase control and wave number control.

A heater unit 20 as an external heating means is constituted by the film 16, the heater 17, the film guide member 18, and the like. The heater unit 20 is heated with the heater 17 facing the heating roller 15. The film guide member 18 is arranged in parallel with the roller 15, and is pressed by a predetermined pressing force against the elasticity of the elastic layer 15 b of the heating roller 15 in the axial direction of the heating roller 15 by urging means (not shown). The heater 17 is pressed against the outer surface of the heating roller 15 via the film 16.

In this embodiment, the heater unit 20 is used.
Is pressed against the heating roller 15 at a total pressure of 120 N, and a nip portion N between the heating roller 15 and the pressure roller 19 is pressed.
The angle between the center of the heating roller and the upstream end of the nip and the angle between the center of the heating roller and the upstream end of the heater, which is located on the upstream side in the rotation direction of the heating roller 15, is within 90 °.

As the heating roller 15 rotates, the endless film 16 of the heater unit 20 is rotated by the frictional force between the outer surface of the heating roller 15 and the outer surface of the film 16. While the inner surface of the film guide member 18 is in close contact with the surface (outer surface) of the heater 17, it slides around the film guide member 18 at a peripheral speed substantially corresponding to the rotational peripheral speed of the heating roller 15 in a counterclockwise direction indicated by an arrow. . By interposing a lubricant such as heat-resistant grease between the heater 17 and the inner surface of the film 16, the rotation of the film 16 can be made smoother.

The heating roller 15 is driven to rotate, whereby the endless film 16 of the heater unit 20 is rotated, and electricity is supplied to the heater 17 so that the heater 17 generates heat and the temperature is controlled to a predetermined temperature. By that
The outer surface of the rotating heating roller 15 is heated to a predetermined fixing temperature by the heat of the heater 17 via the film 16 by the external heating method. Here, the control temperature of the heater 17 is changed according to the number of sheets passed,
The temperature may be detected and adjusted by bringing a temperature detecting element such as a thermistor into contact with itself.

The recording material 1 carrying the unfixed toner image 10 in the nip N between the heating roller 15 and the pressure roller 19
1 is introduced, and the nip portion N is nipped and conveyed, so that the heating roller 8 heats and fixes the unfixed toner image 10 on the recording material 11.

With this configuration, the surface of the heating roller 15 follows the unevenness of the toner image on the recording material 11, which is the material to be heated, by the elasticity of the elastic layer 15b. Therefore, it is possible to obtain a good fixed image without unevenness even for a color image or a bond paper having a rough surface.

In the conventional fixing device of the film heating type, the sliding force of the film and the conveying force of the recording material are supplied from the pressure roller. However, since the pressure roller expands due to heat,
There is a problem that the speed of the recording material increases and the image expands. For this reason, it has been proposed to compress the image on the photosensitive drum.

In the present embodiment, however, the coefficient of thermal expansion of the heating roller 15 is 1/30 to 1/1 of rubber since the roller base 15a (cellar) is manufactured using glass as a base material.
By utilizing the small value of 0, the heater unit 16 and the pressure roller 19 of the film heating system can be driven by the heating roller 15, so that there is no problem in image elongation.

<Second Embodiment> The fixing device 1 of the first embodiment described above.
08, the pressure roller 19 has an elastic layer 19b made of a solid silicone rubber. More preferably, the pressure roller 19 has a sponge layer. preferable.

In this case, the temperature distribution along the length of the heater on the side of the heater unit 16 which is the external heating means of the heating roller 15 is preferably adjusted according to the width of the recording material to be fed. A method has been disclosed so far in which a plurality of heating resistors are provided in a branched manner on a heater to independently control energization. This method may be used.

FIG. 4 shows an example of a ceramic heater in which the heating area is switched according to the width of the recording material to be passed. Constituent members and portions common to the above-described ceramic heater of FIG. 3 are denoted by the same reference numerals, and description thereof will not be repeated.

A is a sheet passing width area of a large size recording material, B is a sheet passing width area of a small size recording material, and C is a non-sheet passing portion area generated when a small size recording material is passed. In the apparatus of the present embodiment, the recording material is passed on the basis of the center conveyance. O is its central reference line.

Reference numeral b1 denotes a first heating resistor layer, the length of which corresponds to the sheet passing width area of a large-size recording material. b
Reference numeral 2 denotes a second heating resistor layer, the length of which corresponds to the sheet passing width area of the small-sized recording material. i is a third current-carrying electrode (input terminal) common to the first and second heating resistor layers b1 and b2, and is electrically connected to the first heating resistor layer b1 via an electric circuit pattern j. It is electrically connected to the second heating resistor layer b2 via the electric circuit pattern k.

When a large-size recording material is passed, the switching circuit 113 is controlled by the control circuit 111 so that the first energizing electrode f is selected, and the first heating resistor layer b
1 is supplied, and the paper passing width area A of the large-sized recording material of the heater 17 generates heat.

When a small-sized recording material is passed, the switching circuit 113 is controlled by the control circuit 111 so that the second current-carrying electrode g is selected, and the second heating resistor layer b
2 is supplied, and the paper passing width area B of the small-sized recording material of the heater 17 generates heat.

Since the material to be heated is insulated on both sides, the amount of heat supplied to the surface of the heating roller can be efficiently conducted to the material to be heated.

As a configuration of the pressure roller 19 used here, as shown in FIG. 5, a silicone sponge layer 19c is formed on a cored bar 19a, and a liquid silicone rubber is further applied to the surface thereof and blade coated. , And the surface layer 1
9d coated with a PFA tube of 50 μm is suitable.

Alternatively, as shown in FIG. 6, instead of the surface layer 19d of the PFA tube, an adhesive (product name: GLP-104QR) of Daikin Industries, Ltd. is applied as an adhesive layer 19e on the surface of the silicone sponge layer 19c. As the surface layer 19f, a latex in which a fluororubber and a fluororesin are mixed (trade name: Daiel Latex GLS213)
A, manufactured by Daikin Industries, Ltd.) and 100 parts of a curing agent for the above latex (trade name: Daiel Latex GLS21)
3B, manufactured by Daikin Industries, Ltd.) 5 parts of a paint is applied so that the dry thickness becomes about 30 μm,
After drying for minutes, a product baked at 310 ° C. for 30 minutes may be used.

As a result, a layer of a cured fluororubber containing a fluororesin is formed to a thickness of about 5 μm on the side of the adhesive layer 19e, and a release layer 19f of a fluororesin layer of about 1.5 μm is formed on the surface thereof.
Was formed.

Alternatively, it is preferable that the thermal conductivity is lowered by adding a hollow spherical filler to silicone rubber instead of the silicone rubber sponge layer 19c.

As hollow spherical fillers to be used, glass balloons, silica balloons, carbon balloons, phenol resin balloons, vinylidene chloride resin balloons, resin balloons composed of a copolymer of vinylidene chloride and (meth) acrylonitrile, alumina balloons, zirconia Balloons, shirasu balloons, etc.

The surface of these hollow spherical fillers is
Those to which calcium carbonate, silica, titanium oxide and the like are adhered are also preferable, and these have a function of improving the dispersibility of the hollow spherical filler in the silicone rubber.

The thermal conductivity of the pressure roller 19 thus produced is 0.09 W / m · K to 0.149 W /
m · K is preferred.

By employing such a configuration, the energy consumption can be reduced to about 1/3 as compared with the first embodiment. This is because the heat capacity of the pressure roller 19 can be reduced to about と 同時 に at the same time as the heat insulation.

According to this embodiment, by changing the amount of heat generated in the paper-passing area and the non-paper-passing area on the heater, abnormal temperature rise in the non-paper-passing area is suppressed, and adverse effects such as cracks in the heater are prevented. .

Further, a heater substrate (heat conductive substrate)
By making the heat distribution of the heater 17 uniform by using an aluminum nitride substrate (AlN) or silicon carbide (SiC) having good thermal conductivity as a, it is possible to suppress the fixing unevenness in the longitudinal direction.

<Embodiment 3> In the fixing device of Embodiment 2 described above, the area where heat is generated by the heater 17 on the side of the heater unit 16 which is the external heating means of the heating roller 15 is switched to suppress heat generation at the end. However, in this embodiment, as the rubber layer of the pressure roller 19, as shown in FIG. 7, a heat conductive elastic layer 19g, specifically, 0.5 W / m · K
Is constituted by using a silicone rubber layer.

In order to improve the heat conduction of the elastic layer 19g, aluminum oxide, titanium aluminum,
Alternatively, a fine particle of a substance such as
It is improved by adding

By using such a pressure roller 19, the heat conduction in the axial direction can be improved. Therefore, as in the second embodiment, the heater on the heater unit 16 side which is the external heating means of the heating roller 15 is used. There is no need to branch and control the 17 heating resistor layers. Therefore, control can be simplified and the heater can be downsized. As a result, the entire device can be reduced in size.

<Other Embodiments> 1) The external heating means 20 of the heating roller 15 is not limited to the film heating type heater unit using the ceramic heater of the embodiment, but may be a contact type or a non-contact type. Any heating means can be used. For example, a heating means of an electromagnetic induction heating type using an induction heating member as a heating body (heater), a heating means such as a halogen lamp, and the like.

2) The pressure rotating body is not limited to the roller type, but may be a rotating belt type.

3) The heating device of the present invention is not only an image heating and fixing device, but also an image heating device for heating a recording material carrying an image to improve the surface properties such as gloss, and an image heating device for performing a temporary deposition process. Of course, it can be widely used as a heating device for a material to be heated, such as a heating device for feeding a sheet-like material and performing a drying process and a laminating process.

[0099]

As described above, according to the present invention, the heating (fixing) speed of the material to be heated realized by the heating apparatus of the heat roller type and the on-demand property of the heating apparatus of the film heating type are realized. A heating device having power saving capability and a device configuration capable of uniformly heating the material to be heated can be obtained. In the case of an image heating device such as a fixing device, the thickness of the toner is reduced. Irrespective of this and without being influenced by the heater or the projections of the film, uniform heating can be performed on the recording material.

[Brief description of the drawings]

FIG. 1 is a schematic configuration model diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is an enlarged cross-sectional model diagram of a fixing device.

3A and 3B are configuration diagrams of a heater, in which FIG. 3A is a partially cutaway plan model diagram on the front surface side of the heater, FIG. 3B is a plan model diagram on the rear surface side of the heater, and FIG. 3C is c- in FIG. It is an enlarged cross-sectional model figure which follows the c line.

FIG. 4 is a partially cutaway plan model view of a front surface side of a heater according to a second embodiment.

FIG. 5 is a schematic cross-sectional view (part 1) of a pressure roller according to a second embodiment.

FIG. 6 is a schematic cross-sectional view (part 2) of a pressure roller according to a second embodiment.

FIG. 7 is a schematic cross-sectional view of a pressure roller according to a third embodiment.

FIG. 8 is a schematic cross-sectional view of a heating device (fixing device) of a heat roller type.

FIG. 9 is a schematic cross-sectional view of a main part of a film heating type heating device (fixing device).

[Explanation of symbols]

15. Heating roller 15a Roller base 15b made of a porous ceramic body Elastic layer 15c Release layer 19 Pressure roller 19a Core 19b Elastic layer 19c Elastic layer (silicone sponge layer)
19d ··· Surface layer (PFA tube) 19e · · · Adhesive layer 19f · · · Release layer 19g · · · Elastic layer (thermally conductive elastic layer) 20 · · · External heating means (heater unit) 16 · · ·
Heat-resistant film 17. Heater 18. Film guide member a. Heater (heat conductive substrate) b, b, b1, b2.
Heating resistor pattern c Overcoat layer d, e, hj, k Conductor pattern f, g, i Electrode 4 thermistor 7 Heater for heat roller fixing device 8 Fixing roller 9 Pressure roller 10. Toner 11. Transfer material 12. Heater for film fixing device 13. Fixing film 14. Film guide 15. Heating roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Kishino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaaki Takahashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in the company (reference) 2H033 AA03 AA20 AA30 BA27 BB03 BB05 BB06 BB13 BB23 3J103 AA02 AA15 AA23 GA02 GA57 GA58 HA03 HA04 HA05 HA12 HA18 HA51 HA53 3K058 AA02 AA86 BA18 CA12 CA23 CA61 CE04 CE12 DA03 DA

Claims (6)

[Claims] 1. A heating roller which rotates, an external heating means for heating the heating roller from outside the roller, and a pressure rotating body which forms a nip portion with the heating roller, wherein the heating roller is covered by the nip portion. A heating device for nipping and transporting the heating material and heating the material to be heated by the heat of the heating roller, wherein the heating roller has a roller base made of a ceramic porous body, and at least an elastic layer is formed on the roller base. A heating device characterized by being formed. 2. The heating device according to claim 1, wherein an elastic layer and a releasable layer are further formed on the roller base. 3. The heating device according to claim 1, wherein the pressing rotator is an elastic roller. 4. An external heating means includes a fixedly supported heating element and a film sliding on the heating element, wherein the heating element is in pressure contact with an outer surface of a heating roller with the film interposed therebetween. The heating device according to any one of claims 1 to 3, wherein an outer surface of the roller is heated by heat of the heating body via the film. 5. The recording material carrying an image, wherein the recording material is nipped and conveyed in a nip portion, and the image on the recording material is heated by heat of a heating roller. 5. The heating device according to any one of items 1 to 4. 6. An image forming apparatus comprising: an image forming unit for forming and carrying an unfixed toner image on a recording material; and a fixing unit for heating and fixing the unfixed toner image on the recording material onto the recording material. An image forming apparatus, wherein the fixing unit is the heating device according to claim 1.