JP2003255755A - Image heating device, image forming apparatus, and temperature control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heating device in which a difference in gloss between the surface and the back of recording paper in both-sided printing and image disturbance caused by re-fusion of toner on the surface are eliminated. <P>SOLUTION: A control means 79 sets the set temperature of a fixing belt 20 when images on the surface and the backside of recording paper 8 are heated lower than that of the fixing belt when images on only one side of the recording paper are heated. Also, the control means 79 sets the set temperature of the fixing belt when images on the surface are heated is lower than that of the fixing belt when images on the backside are heated. Thus, even when the surface is passed through the image heating device twice during both-sided printing, the gloss of the surface is prevented from becoming higher than that of the backside and toner re-fusion on the surface is prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating apparatus suitable for a fixing device for fixing an unfixed toner image by heating a conductive belt directly or indirectly through a metal roller by electromagnetic induction. The present invention also relates to an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus using the image heating apparatus, and a temperature control method applied to the image heating apparatus and the image forming apparatus.

[0002]

2. Description of the Related Art As an image heating apparatus represented by a fixing apparatus, a contact heating type image heating apparatus such as a roller heating type and a belt heating type has been generally used.

In recent years, an electromagnetic induction heating system, which has a possibility of rapid heating and high efficiency heating, has been attracting attention due to demands for shortening warm-up time and energy saving. In the belt heating method, a conductive belt having a smaller heat capacity is used in order to shorten the warm-up time. And
A high-frequency current is passed through the exciting coil, and a high-frequency magnetic field generated thereby generates an induced eddy current in the conductive belt, causing the conductive belt itself to generate Joule heat. By passing a recording medium (paper, OHP film, etc.) on which an unfixed toner image is formed, through a nip portion between a fixing roller and a pressure roller that are pressed against each other via the conductive belt that has generated heat,
An unfixed toner image can be fixed.

In the roller heating method, a metal roller having a thinner wall thickness is used in order to shorten the warm-up time. Then, a high-frequency current is passed through the exciting coil, an induced eddy current is generated in the metal roller by the high-frequency magnetic field generated by this, the Joule heat is generated in the metal roller, and the nip portion between the pressure roller and the metal roller is provided.
Alternatively, a recording medium (paper, OHP film, or the like) on which an unfixed toner image is formed in a nip portion between a fixing roller and a pressure roller facing the fixing roller via a heat-resistant resin belt that conveys heat conducted from a metal roller. ), An unfixed toner image can be fixed.

[0005]

However, when the above-mentioned image heating apparatus is applied to an image forming apparatus having a double-sided printing function, after the image heating of the surface of the recording medium is performed, the recording medium is moved to a predetermined position. It is transported, and then switched back to heat the image on the back side. In this case, the back surface of the recording medium is heated only once by the belt, but the front surface of the recording medium is heated twice by the belt at the first time and twice by the pressure roller in which heat is accumulated. Therefore, the gloss of the toner image on the front surface becomes higher than that on the back surface, and the toner on the front surface is remelted by the second heating,
The image becomes distorted.

The present invention has been made in view of the above problems, and an object thereof is to prevent a difference in glossiness between the front surface and the back surface of a recording medium during double-sided printing, and to disturb an image due to remelting of toner on the front surface. An object of the present invention is to provide an image heating apparatus that has been eliminated, an image forming apparatus using the image heating apparatus, and a temperature control method applied to the image heating apparatus and the image forming apparatus.

[0007]

In order to achieve the above object, an image heating apparatus according to the present invention is provided with a material to be heated (recording paper,
A movable heating member for directly heating the OHP film or the like), a heat generating means for directly or indirectly heating the heating member, and a pressure means having a roller shape and abutting the heating member,
A temperature sensor for detecting the temperature of the heating member and a control unit for controlling the amount of heat generated by the heating unit so that the temperature of the heating member reaches a set temperature based on the temperature detected by the temperature sensor are provided. When the image heating of the front surface and the back surface of the heating material is performed, the set temperature of the heating member at the time of image heating of the front surface and / or the back surface is set to the heating member when performing the image heating of only one surface of the heated material. The feature is that the temperature is set lower than the temperature.

In this case, the control means sets the set temperature of the heating member at the time of image heating of the front surface and the set temperature of the heating member at the time of image heating of the back surface when performing image heating of the front surface and the back surface of the material to be heated. Are preferably different from each other.

According to the above arrangement, it is possible to eliminate the difference in glossiness between the front surface and the back surface of the recording medium during double-sided printing and the image disturbance due to the remelting of the toner on the front surface.

In the image heating apparatus according to the present invention, at least a part of the heating member has conductivity (conductive belt),
The heat generating means includes an exciting means for directly heating the heating member by using electromagnetic induction, or the heat generating means is inscribed in the heating member and at least a part of which has conductivity, and the heating member (for example, a heat-resistant material). It is configured to include a rotatable heat generating member (for example, a metal roller) that indirectly heats a resin belt, and an excitation unit that heats the heat generating member using electromagnetic induction.

Further, in the image heating apparatus according to the present invention,
The heating member (belt) preferably has a heat capacity of 60 J / K or less, more preferably 40 J / K or less.

When the heat capacity of the belt is set to 60 J / K or less, if the heating means heats the belt with an input power of 1000 W, the portion actually heated is considered to be 1/10 or less of this in a stationary state. The belt temperature can be increased to 200 ° C. or higher in a short time of about 1 second.
When the heat capacity of the belt is set to 40 J / K or less, 9
When the belt is heated by the heating means with an input power of 00 W, the temperature of the belt can be raised to several hundreds of degrees Celsius or more in a short time of about 1 second.

Further, in the image heating apparatus according to the present invention,
It is preferable that the control unit changes the set temperature of the heating member before the heating of the immediately preceding heated material is completed.

According to this structure, the throughput (the number of printed sheets / minute) equivalent to that of single-sided printing can be ensured even in double-sided printing.

In the image heating apparatus according to the present invention, in order to make the temperature detected by the temperature sensor for the heating member and the ambient temperature in the vicinity of the temperature sensor substantially equal, the material to be heated (paper, O
It is preferable to include a cover that covers a space occupied by at least a part of the heating member (belt), the temperature sensor, and the pressing unit (pressing roller) excluding the passage portion of the HP film).

According to this structure, the temperature of the pressure roller can be prevented from becoming higher than the temperature of the belt by making the detected temperature of the belt and the ambient temperature thereof coincide with each other. Can be estimated appropriately.

In order to achieve the above object, the first image forming apparatus according to the present invention records an image forming means for forming and carrying an unfixed toner image on a recording medium which is a material to be heated and a toner image. An image forming apparatus including a fixing device for thermally fixing to a medium, wherein the fixing device is an image heating device according to the present invention.

According to the configuration of the first image forming apparatus,
It is possible to realize an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, which has the advantages of the image heating apparatus according to the present invention. In this case, a cover for making the detected temperature of the heating member and the ambient temperature in the vicinity of the temperature sensor approximately match is provided on the image heating device side.

In order to achieve the above object, the second image forming apparatus according to the present invention comprises an image forming means for forming and carrying an unfixed toner image on a recording medium which is a material to be heated, and the toner image. An image forming apparatus having a detachable fixing device for heat fixing to a recording medium, wherein the fixing device is an image heating device according to the present invention having no cover, and the image forming device is equipped with the fixing device. At this time, in order to substantially match the temperature detected by the temperature sensor with the heating member and the ambient temperature in the vicinity of the temperature sensor, at least a part of the heating member (belt) excluding the passage portion of the material to be heated, the temperature sensor, And a cover for covering the space occupied by the pressure means (pressure roller).

According to the configuration of the second image forming apparatus,
It is possible to realize an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, which has the advantages of the image heating apparatus according to the present invention. In this case, a cover for making the detected temperature of the heating member and the ambient temperature in the vicinity of the temperature sensor approximately match is provided on the image forming apparatus side with the image heating apparatus removed.

In order to achieve the above object, the first temperature control method according to the present invention comprises a movable heating member (belt) for directly heating a material to be heated (recording paper, OHP film, etc.), and a heating member. A heating means for directly or indirectly heating the heating member, a pressing means having a roller shape for contacting the heating member, a temperature sensor for detecting the temperature of the heating member, and a temperature sensor for detecting the temperature of the heating member. In order to substantially match the detection temperature of the heating member by the temperature sensor and the ambient temperature in the vicinity of the temperature sensor with the control unit that controls the heat generation amount of the heat generation unit so that the temperature becomes the set temperature, the passage portion of the material to be heated passes. At least a part of the heating member (belt), the temperature sensor, and the pressing means (pressing roller)
A temperature control method applied to an image heating apparatus having a cover for covering a space occupied by the heating member, the heating member being used for image heating of the front surface and / or the back surface of the material to be heated when the image heating is performed. The set temperature of is set lower than the set temperature of the heating member when performing image heating on only one side of the material to be heated, and the set temperature changed in the set temperature change step is controlled Heat generation amount control step of controlling the heat generation amount of the heat generation means by means.

According to the configuration of the first temperature control method,
A temperature control method suitable for the image heating apparatus according to the present invention having a cover can be realized.

In order to achieve the above object, the second temperature control method according to the present invention comprises an image forming means for forming and carrying an unfixed toner image on a recording medium which is a material to be heated, and a recording medium (recording medium). Movable heating member (belt) for directly heating paper, OHP film, etc., heating means for directly or indirectly heating the heating member, pressurizing means having a roller shape and contacting the heating member, heating Based on the temperature sensor that detects the temperature of the member and the temperature detected by the temperature sensor,
A detachable image heating device having a control means for controlling the amount of heat generated by the heating means so that the temperature of the heating member reaches the set temperature, and a detachable image heating device for thermally fixing the toner image on the recording medium, and the image heating device are mounted. At this time, in order to substantially match the temperature detected by the temperature sensor with the heating member and the ambient temperature in the vicinity of the temperature sensor, at least a part of the heating member (belt) excluding the passage portion of the material to be heated, the temperature sensor, A temperature control method applied to an image forming apparatus comprising: a cover for covering a space occupied by a pressurizing unit (pressurizing roller); And / or the set temperature changing step of setting the set temperature of the heating member during image heating of the back side lower than the set temperature of the heating member when performing image heating of only one side of the material to be heated, and the set temperature change step. So that the changed setting temperature in, characterized in that it comprises a heating amount control step for controlling the heating value of the heating means by the control means.

According to the structure of the second temperature control method,
It is possible to realize the fixing temperature control suitable for the image forming apparatus including the detachable image heating apparatus according to the present invention having no cover and the cover for the image heating apparatus.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a schematic sectional view showing the overall structure of a color image forming apparatus having a double-sided printing function, which uses an image heating apparatus according to an embodiment of the present invention as a fixing device. The configuration of this apparatus and the operation during double-sided printing will be described below.

In FIG. 1, reference numeral 1 is an electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum). The surface of the photosensitive drum 1 is uniformly charged to a predetermined negative dark potential V0 by a charger (not shown) while being rotationally driven in the direction of the arrow at a predetermined peripheral speed. The uniformly charged surface of the photosensitive drum 1 is scanned and exposed by a laser beam modulated in accordance with a time series electric digital pixel signal of image information input from a host device such as an image reading device or a computer (not shown). It As a result, the absolute value of the potential of the exposed portion of the photosensitive drum 1 decreases to the bright potential VL, and an electrostatic latent image is formed on the surface of the photosensitive drum 1. The photosensitive drum 1 has four colors corresponding to four color images of yellow (Ye), magenta (Ma), cyan (Cy), and black (Bk).
One is provided.

The electrostatic latent image formed on the surface of each photosensitive drum 1 has a Ye developing unit 91, a Ma developing unit 92, and a Cy developing unit 9.
3. Reversal development is performed by the negatively charged toner of the Bk developing device 94 to visualize the image.

The Ye toner image, the Ma toner image, the Cy toner image, and the Bk toner image formed on the surface of each photosensitive drum 1 are superimposed and transferred onto the intermediate transfer unit 98, thereby forming four color toner images. To be done. The color toner image is transferred onto the surface of the recording paper 8 that is fed in synchronism with the registration roller 97 by the secondary transfer roller 96 to which a transfer bias is applied, and is fused and fixed by the fixing device 14. .

The recording paper 8 discharged from the fixing device 14 is
After the paper is discharged halfway, it is switched back and drawn into the automatic duplex unit 95. The recording medium 8 discharged from the automatic double-sided unit 95 has its front surface and back surface reversed and is conveyed to the registration roller 97. After that, in the same manner as the front surface, the color toner image is transferred onto the back surface of the recording paper 8 by the secondary transfer roller 96, and is fused and fixed by the fixing device 14.

Next, regarding the image heating apparatus of this embodiment,
It will be described in more detail with a specific example.

FIG. 2 is a sectional view showing the structure of the fixing device 14 as an image heating device used in the color image forming apparatus of FIG.

In FIG. 2, reference numeral 25 is an exciting coil which constitutes a part of the exciting means 24. This exciting coil 25 is
It is formed by using a litz wire that is a bundle of thin wires, and has a cross-sectional shape that covers the fixing belt 20 wound around the heat roller 21. A core material 26 made of ferrite is provided at the center of the exciting coil 25 and a part of the back surface thereof. As the material of the core material 26, besides ferrite, a material having a high magnetic permeability such as permalloy can be used. The exciting coil 25 is provided outside the heat generating roller 21,
An exciting current of, for example, 23 kHz is applied from the exciting circuit 75. As a result, a part of the heat generating roller 21 is heated by electromagnetic induction.

A temperature sensor 45 is provided at a portion of the fixing belt 20 that has passed the contact portion with the heat generating roller 21 so as to come into contact with the back surface of the fixing belt 20. With this, the temperature of the fixing belt 20 is detected. It

Reference numeral 79 is a control means, and the control means 79 is
Based on the temperature of the fixing belt detected by the temperature sensor 45 and the amount of change of the temperature with respect to time, the electric power supplied to the exciting coil 25 via the exciting circuit 75 is controlled so that the optimum fixing temperature is obtained, thereby generating heat. The heat generation amount of the roller 21 is controlled. This control method will be described in detail later.

Reference numeral 28 is a coil guide as a holding member. The coil guide 28 is made of a resin having a high heat resistance temperature such as PEEK material or PPS, and is integrated with the exciting coil 25 and the core material 26. In this way, the coil guide 2
By providing 8, the heat radiated from the heat generating roller 21 can be prevented from being trapped in the space between the heat generating roller 21 and the exciting coil 25 and damaging the exciting coil 25.

In FIG. 2, the core material 26 has a semicircular cross section, but the core material 26 does not necessarily have to have a shape that follows the shape of the exciting coil 25. For example, the shape may be approximately Π.

The thin fixing belt 20 has a base material made of a polyimide resin having a glass transition point of 360 ° C. and a diameter of 50 mm.
It is an endless belt having a thickness of 90 μm. The surface of the fixing belt 20 is coated with a release layer (not shown) made of fluororesin and having a thickness of 30 μm in order to impart releasability. As the material of the base material, in addition to the polyimide resin used in this example, a resin having heat resistance such as a fluororesin can be used. The glass transition point of the base material of the fixing belt 20 is preferably 200 ° C to 500 ° C.
Further, as the release layer on the surface of the fixing belt 20, PTF is used.
Resins and rubbers having good releasability such as E, PFA, FEP, silicone rubber, and fluororubber may be used alone or in combination. When the fixing belt 20 is used for fixing a monochrome image, only releasability is required to be secured, but when the fixing belt 20 is used for fixing a color image, it is desirable to impart elasticity, and in that case. Needs to form a thicker rubber layer. Also, the fixing belt 2
The heat capacity of 0 is preferably 60 J / K or less, more preferably 40 J / K or less.

The fixing belt 20 includes a fixing roller 22 and a heat generating roller 21 each having a low thermal conductivity and a diameter of 20 mm, which are made of silicone rubber, which is a foam having a low hardness (JIS A30 degrees) and elasticity. It is suspended with the tension of, and can rotate and move in the direction of arrow B.

The heat generating roller 21 has a diameter of 30 mm and a length of 3
It is made of a cylindrical SUS430 having a thickness of 20 mm and a thickness of 0.5 mm, and has a heat capacity of 54 J / K. The heat roller 21
As the material of SUS430, other magnetic metal such as iron can be used in addition to SUS430. The heat capacity of the heat generating roller 21 is preferably 60 J / K or less, more preferably 40 J / K or less.

The pressure roller 23 is made of silicone rubber having a hardness of JIS A65 degrees and is pressed against the fixing roller 22 via the fixing belt 20 to form a nip portion. In this state, the pressure roller 23 is supported so as to rotate with the rotation of the fixing roller 22.
As the material of the pressure roller 23, other heat resistant resin such as fluororubber or fluororesin or rubber may be used. Further, in order to improve abrasion resistance and releasability, it is desirable that the surface of the pressure roller 23 is coated with a resin or rubber such as PFA, PTFE, FEP, etc., alone or in a mixture. Further, in order to prevent heat dissipation, the pressure roller 23 is preferably made of a material having low heat conductivity.

The heat generating roller 21 is rotationally driven by a drive source of the apparatus body (not shown). In addition, the fixing roller 22
Rotates with the rotation of the heat generating roller 21 via the fixing belt 20. Further, the pressure roller 23 is the fixing belt 2
It rotates with the rotation of the fixing roller 22 via 0.

90 is the fixing belt 20 and the heat generating roller 2.
1, fixing roller 22, temperature sensor 45, pressure roller 23
Is a cover that encloses the space occupied by the pressure roller 23. By making the temperature of the fixing belt 20 and the ambient temperature thereof coincide with each other, the temperature of the pressure roller 23 is prevented from becoming higher than the temperature of the fixing belt 20. Therefore, the temperature of the pressure roller can be properly estimated.

As shown in FIG. 2, the recording paper 8 on which the color toner image is transferred by the color image forming apparatus shown in FIG. 1 is transferred to the fixing device 14 having the above-described structure.
The color toner image 11 on the recording paper 8 can be heat-fixed by making the surface on which 1 is transferred face upward and projecting from the direction of arrow F.

Next, using the fixing device 14 as described above,
Regarding the method of changing the fixing temperature between the front surface and the back surface of the recording paper 8 during double-sided printing, in addition to FIG. 1 and FIG.
And it demonstrates with reference to FIG.

FIG. 3 is a flowchart showing the processing steps in the fixing temperature control routine applied to the fixing device 14 as the image heating apparatus and the color image forming apparatus according to this embodiment.

FIG. 4 is a signal timing chart showing the operation of each part in the color image forming apparatus of FIG.

In FIG. 3, first, when a print request for double-sided printing is generated by the user (S301) and the print signal S1 (FIG. 4) is input to the control means 79 (FIG. 2), the signal S2 is output.
(FIG. 4) is activated (to a logic “H” level), and the preheating mode in which the preset temperature of the fixing belt 20 is set lower than that during fixing when waiting for a print request rises to the preset temperature required for fixing. The fixing heating mode is started (S30
2). Next, the set temperature of the fixing belt 20 is set to the recording paper 8
The surface fixing temperature T _H1 for fixing the color toner image on the surface of the is changed (S303). This surface fixing temperature T
_H1 is set to 165 ° C., which is lower than 170 ° C. which is the set temperature for single-sided printing, for example.

Next, the image forming signal S3 shown in FIG. 2 is activated, the photosensitive drum 1 is exposed to the laser beam, and the Ye developing device 91,
A Ye toner image, a Ma toner image, a Cy toner image, and a Bk toner image are formed by each of the Ma developing device 92, the Cy developing device 93, and the Bk developing device 94, and the color toner image is transferred onto the intermediate transfer unit 98. It At the timing before the image forming signal S3 is deactivated, the paper feed signal S4 is activated, and the recording paper 8 is fed thereby, and the registration roller 9 responds to the registration roller signal S5.
7, the color toner image on the intermediate transfer unit 98 is transferred onto the surface (first surface) of the recording paper 8 by the secondary transfer roller 96 in response to the secondary transfer signal S6.

Next, during the transfer to the surface, the color toner is transferred onto the surface of the recording paper 8 by the fixing belt 20 whose set temperature is set to the surface fixing temperature T _H1 according to the first fixing signal S7. The image is fixed. When the transfer to the front surface according to the secondary transfer signal S6 is completed, the image forming signal S3 is activated again, and the color toner image for the back surface is formed.

Returning again to the flow of FIG. 3, the fixing signal S is used to determine whether the fixing of the color toner image on the surface is completed.
The determination is made based on the trailing edge of 7 (S304). If the result of determination in step S304 is that fixing on the front surface has ended (Yes), the recording paper 8 indicates that the paper discharge sensor signal S
After the paper is ejected to a predetermined position according to No. 9, the switch back is performed according to the automatic double-sided signal S8, and the automatic double-sided unit 95
Be drawn into.

At this time, at a predetermined timing, the set temperature of the fixing belt 20 is changed to the back surface fixing temperature _TH2 for fixing the color toner image on the back surface of the recording paper 8 (S2).
305). The back surface fixing temperature T _H2 is set to, for example, 167 ° C., which is higher than the _front surface fixing temperature T _H1 (165 ° C.) and lower than the set temperature (170 ° C.) for single-sided printing.

The recording paper 8 discharged from the automatic double-sided unit 95 has the front surface and the back surface thereof reversed, and the color toner image is fixed to the back surface (second surface) by the same process as the front surface. Will be ejected.

As described above, according to this embodiment, the difference in glossiness between the front surface and the back surface of the recording paper 8 during double-sided printing,
Further, it is possible to eliminate the image disturbance due to the remelting of the toner on the surface.

In the present embodiment, only double-sided printing (front side → back side) on one recording sheet has been described as an example. However, in the case of two recording sheets, the first side of the first sheet → the first side of the recording sheet. Of the back side of the second sheet → the front side of the second sheet → the pattern of printing on the back side of the second sheet and the front side of the first sheet → the surface of the second sheet → the back side of the first sheet → the pattern of printing on the back side of the second sheet There are two ways.
When performing double-sided printing on three or more recording sheets, the front side of the first sheet → the back side of the first sheet → the front side of the second sheet → the back side of the second sheet → the front side of the third sheet → the back side of the third sheet. There are two patterns: a pattern to be printed on, and a pattern for printing on the front side of the first sheet → the front side of the second sheet → the back side of the first sheet → the front side of the third sheet → the back side of the second sheet → the back side of the third sheet. There is.

In the present embodiment, the heat generation roller 21 is caused to generate heat by electromagnetic induction and the fixing belt 20 is indirectly heated. Fixing belt 2
Alternatively, the fixing belt 20 may be directly heated by electromagnetic induction. In this case, as the conductive fixing belt 20, for example, a nickel electroformed belt base material having a thickness of 30 μm and a diameter of 60 mm coated with 150 μm of silicone rubber for fixing a color image is used.

In the present embodiment, the temperature detected by the temperature sensor 45 of the fixing belt 20 and the temperature sensor 45.
The cover 90 for substantially matching the ambient temperature in the vicinity of is illustrated as being attached to the image heating apparatus side, but it is provided on the image forming apparatus side with the image heating apparatus removed, and the image heating apparatus is installed. When mounted, the fixing belt 20,
It may be configured to include the space occupied by the temperature sensor 45 and the pressure roller 23.

[0058]

As described above, according to the present invention,
By eliminating the difference in glossiness between the front surface and the back surface of the recording medium and the image disturbance due to the remelting of the toner on the front surface, it becomes possible to perform double-sided printing with throughput and quality equivalent to single-sided printing.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an overall configuration of a color image forming apparatus using an image heating apparatus according to an embodiment of the present invention as a fixing device.

FIG. 2 is a cross-sectional view showing a specific configuration of the image heating apparatus shown in FIG.

3 is a flowchart showing processing steps in a fixing temperature control routine applied to the image heating apparatus and the image forming apparatus of FIG.

4 is a signal timing chart showing the operation of each part in the color image forming apparatus of FIG.

[Explanation of symbols]

8 Recording medium (heated material) 11 color toner image 14 Fixing device (image heating device) 20 Fixing belt (heating member) 21 Heat generating roller (heat generating means) 22 Fixing roller 23 Pressure Roller (Pressure Means) 24 Excitation means 25 Excitation coil 45 Temperature sensor 75 Excitation circuit 79 control means 90 cover 91 Ye Developer 92 Ma developing device 93 Cy Developer 94 Bk developing device 95 Automatic duplex unit 96 Secondary transfer roller 97 Registration roller 98 Intermediate transfer unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaru Imai             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Tadafumi Shimizu             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Masahiro Sakai             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Keiichi Matsuzaki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kazunori Matsuo             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Ikuichi Kitagawa             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 2H033 AA01 AA46 BA04 BA11 BA12                       BA30 BB18 BE03 BE06 CA07                       CA08 CA48                 3K059 AB19 AB28 AC33 AD05 AD18                       CD14

Claims (13)

[Claims] 1. A movable heating member that directly heats a material to be heated; a heat generating unit that directly or indirectly heats the heating member; a pressure unit that has a roller shape and abuts on the heating member; A temperature sensor that detects the temperature of the heating member; and a control unit that controls the heat generation amount of the heat generating unit so that the temperature of the heating member reaches a set temperature, based on the temperature detected by the temperature sensor, The control means, when performing image heating of the front surface and the back surface of the heated material, sets the temperature of the heating member at the time of image heating of the front surface and / or the back surface, and performs image heating of only one surface of the heated material. In this case, the image heating device is set to a temperature lower than the set temperature of the heating member. 2. The heating member is at least partially conductive, and the heat generating means includes an exciting means for directly heating the heating member using electromagnetic induction. Image heating device. 3. The heat generating means is inscribed in the heating member, at least a part of which has conductivity, and the rotatable heat generating member indirectly heats the heating member; and the heat generation using electromagnetic induction. An image heating apparatus according to claim 1, further comprising an exciting means for heating the member. 4. The image heating apparatus according to claim 1, wherein the heating member has a belt shape. 5. The image heating apparatus according to claim 1, wherein the heating member has a heat capacity of 60 J / K or less. 6. The image heating apparatus according to claim 1, wherein the heating member has a heat capacity of 40 J / K or less. 7. The set temperature of the heating member at the time of image heating of the front surface and the set temperature of the heating member at the time of image heating of the back surface when performing image heating of the front surface and the back surface of the material to be heated. 7. The image heating apparatus according to claim 1, wherein the set temperature is different from each other. 8. The image according to claim 1, wherein the control means changes the set temperature of the heating member before the heating of the immediately preceding heated material is completed. Heating device. 9. The image heating apparatus, wherein the temperature of the heating member detected by the temperature sensor is substantially the same as the ambient temperature in the vicinity of the temperature sensor, except for the passage portion of the material to be heated, 9. The image heating apparatus according to claim 1, further comprising a cover that covers a space occupied by at least a part of a heating member, the temperature sensor, and the pressurizing unit. 10. An image forming apparatus comprising: an image forming unit that forms and carries an unfixed toner image on a recording medium that is a material to be heated; and a fixing device that thermally fixes the toner image on the recording medium. An image forming apparatus, wherein the fixing device is the image heating device according to any one of claims 1 to 9. 11. An image forming apparatus comprising: an image forming unit for forming and carrying an unfixed toner image on a recording medium which is a material to be heated; and a detachable fixing device for thermally fixing the toner image on the recording medium. A device, wherein the fixing device is the image heating device according to any one of claims 1 to 8, and the image forming device, when the fixing device is mounted,
In order to substantially match the detected temperature of the heating member by the temperature sensor and the ambient temperature in the vicinity of the temperature sensor, at least a part of the heating member, excluding the passage portion of the material to be heated, the temperature sensor, An image forming apparatus comprising: a cover for covering a space occupied by the pressing unit. 12. A movable heating member for directly heating a material to be heated, a heating means for directly or indirectly heating the heating member, and a pressing means having a roller shape and abutting on the heating member. A temperature sensor that detects the temperature of the heating member; a control unit that controls the amount of heat generated by the heating unit so that the temperature of the heating member reaches a set temperature based on the temperature detected by the temperature sensor; In order to substantially match the temperature detected by the heating member with the ambient temperature in the vicinity of the temperature sensor, the heating member, the temperature sensor, and the pressurizing unit occupy the portion excluding the passage portion of the material to be heated. A temperature control method applied to an image heating apparatus having a cover containing a space, in the case of performing image heating of the front surface and the back surface of the material to be heated,
A set temperature changing step of setting the set temperature of the heating member during image heating of the front surface and / or the back surface to be lower than the set temperature of the heating member when performing image heating on only one surface of the material to be heated; And a heat generation amount control step of controlling the heat generation amount of the heat generation means by the control means so that the set temperature changed in the set temperature change step is reached. 13. An image forming unit for forming and carrying an unfixed toner image on a recording medium which is a material to be heated, a movable heating member for directly heating the recording medium, and the heating member directly or indirectly. Heating means for heating to
Pressurizing means having a roller shape and contacting the heating member,
A temperature sensor that detects the temperature of the heating member, and based on the temperature detected by the temperature sensor, a control unit that controls the heat generation amount of the heat generation unit so that the temperature of the heating member reaches a set temperature, A detachable image heating device for thermally fixing the toner image on the recording medium, and a temperature detected by the temperature sensor for the heating member and an ambient temperature in the vicinity of the temperature sensor when the image heating device is mounted. Applied to an image forming apparatus provided with a cover for covering a space occupied by at least a part of the heating member, the temperature sensor, and the pressurizing unit, excluding a passage portion of the material to be heated. In the case of performing the image heating of the front surface and the back surface of the material to be heated,
A set temperature changing step of setting the set temperature of the heating member during image heating of the front surface and / or the back surface to be lower than the set temperature of the heating member when performing image heating on only one surface of the material to be heated; And a heat generation amount control step of controlling the heat generation amount of the heat generation means by the control means so that the set temperature changed in the set temperature change step is reached.