JPH063983A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device capable of uniformizing the temperature distribution of an exothermic body, controlling the offset of a film due to a temperature difference and preventing the excessive temperature rising at the non-paper passing part of a heating body. CONSTITUTION:As to the fixing device for fixing an unfixed image lying on a recording material by bringing a fixing film in contact with the heating body 1 and moving it, bringing a recording material in tight contact with the fixing film and making the recording material to pass through the heating body 1 with the fixing film and giving heat energy to the recording material from the heating body 1 through the fixing film, the heating body 1 is constituted of a resistance exothermic body 1b provided with energizing electrodes 4a and 4b installed on both end parts of the body 1b in a direction orthogonally crossed with a recording material moving direction, plural branch circuits 1d-1g branching from the resistance exothermic body 1b and arranged parallel to the body 1b and a heating controller(heating control means) 14 for the branch circuits 1d-1g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device of an image forming apparatus such as a copying machine or a laser beam printer, and more particularly, a fixing film is brought into contact with a heating member to move the fixing film, and the fixing film is opposed to the heating member. Adhesion of the recording material to the side surface, moving this together with the film to pass through the heating element, and applying heat energy from the heating element to the recording material via the fixing film, the unfixed image transferred onto the recording material The present invention relates to a fixing device that fixes an image.

[0002]

2. Description of the Related Art Conventionally, a fixing device which employs a heat roller fixing method has been widely used. This fixing device
The unfixed image transferred onto the recording material is heated by nipping and transporting the recording material by a heating roller heated to a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. It is a device that is fixed by pressure.

However, such a heat roller fixing device has the following drawbacks.

That is, firstly, the time required to rise to a predetermined temperature (the time during which the image forming operation is prohibited, so-called wait time) is long, and secondly, a large heat capacity is required, so that a relatively large amount of electric power is required. Thirdly, since the heating roller becomes high in temperature, it must be supported by a heat-resistant special bearing. Fourthly, it is dangerous to directly touch the heating roller with a hand, so that the heating roller is covered. Fifth, there is a drawback that the recording material is wound around the roller due to heat and the curvature of the roller, which causes a jam.

Therefore, the present applicant previously proposed a fixing device adopting a film fixing system (SURF system) as a fixing device for solving the above-mentioned problem (Japanese Patent Laid-Open No. 63-3131).
No. 82).

Here, the fixing device adopting the film fixing method will be outlined with reference to FIGS. 40 and 41. Incidentally, FIG.
Reference numeral 0 is a configuration diagram of the fixing device, and FIG. 41 is a sectional view of the heating body.

In FIG. 40, reference numeral 1 is a heating element, which is supported by a holder 2 having a high heat insulating property.
A driving roller 8 and a tension roller 9 are rotatably arranged above the heating element 1. A thin endless belt-shaped fixing film 7 is wound around the driving roller 8, the tension roller 9 and the heating element 1. It is equipped.

A pressure roller 10 is attached to the heating element 1.
Are pressed against each other with the fixing film 7 sandwiched therebetween, and a fixing nip portion is formed at a portion where the pressure roller 10 is pressed against the heating body 1.

By the way, as the heating element 1, as shown in FIG. 41, a resistance heating element 1b is screen-printed on a heater substrate 1a such as an alumina substrate, and a glass coat layer 1c is formed on the resistance heating element 1b. Is configured. The glass coat layer 1c is in contact with the fixing film 7 and has high insulation and slipperiness.

When the driving roller 8 is rotationally driven, the fixing film 7 wound around the driving roller 8 moves and slides on the heating body 1, and the movement of the fixing film 7 causes the pressure roller 10 to move. Followed rotation. The heating element 1 has energizing electrodes (not shown) at both ends in the longitudinal direction (the direction perpendicular to the paper surface of FIG. 40), and when a voltage is applied to the heating element 1 from both electrodes, the heating element 1 has a unit length. It generates heat with a predetermined amount of heat generation.

Therefore, the recording material is brought into close contact with the fixing film 7 and moved together therewith, so that the heating body 1 and the pressure roller 1 are moved.
When passing through the fixing nip portion with 0, heat energy is given to the recording material from the heating body 1 through the fixing film 7,
The unfixed image transferred to the recording material is fixed.

By the way, the effective total length area of the resistance heating element 1b in the conventional heating element 1 is the width (maximum width, maximum size width) of the maximum size recording material that can be supplied and used in the image forming apparatus incorporating the fixing device. ) Is set to a length corresponding to. Therefore, when fixing is performed, the effective total length of the resistance heating element 1b generates a predetermined amount of heat generation per unit length,
Therefore, regardless of the size of the recording material used,
The predetermined image fixing process is performed on the recording material having the maximum usable width and recording materials of various sizes smaller than that.

[0013]

However, the heating element 1 inevitably has a temperature distribution (resistance distribution) in the longitudinal direction in manufacturing, and if the temperature distribution is set within a certain prescribed range, the productivity is increased. Will decrease. In fact, it is extremely difficult to manufacture the heating element 1 having a truly uniform temperature distribution.

Therefore, although the temperature distribution of the heating element 1 must be tolerated to some extent, if the temperature distribution deviates from a certain specified range, non-uniform fixing may be performed in the longitudinal direction. So-called film deviation control suffers from adverse effects. In addition, there is a possibility that excessive temperature rise may occur in the non-sheet passing portion of the heating element 1.

Therefore, the object of the first invention is to make the temperature distribution of the heating element uniform, to control the film deviation due to the temperature difference, and to suppress the excessive temperature rise of the non-sheet passing portion of the heating element. It is to provide a fixing device.

Further, in the conventional heat roller fixing system, since the heating roller, which is a heating body, is maintained at a predetermined temperature over the entire heating area, when a recording material of a size smaller than the maximum size recording material is used. Since heat is not taken by the recording material in the non-sheet passing portion of the heating roller, the temperature of the heating roller is kept higher than that of the portion where the recording material passes (sheet passing portion). This leads to wasteful consumption of electric power, which may cause damage to the heating roller and the pressure roller due to excessive temperature rise in the non-sheet passing portion of the heating roller. Note that FIG. 42 shows the temperatures of the sheet passing portion and the non-sheet passing portion of the heating element (heating roller).

On the other hand, the conventional film fixing system (SURF
In the method), when the recording material is supplied manually, the energization control is performed so that the heating element 1 generates heat over the entire heating entire length area corresponding to the maximum size recording material width. When the width is smaller than the width of the maximum size recording material, the heat energy of the non-sheet passing portion of the heating element 1 is not used for image fixing, and the excessive temperature rise of the non-sheet passing portion of the heating element 1 occurs. The same problem occurs with.

Therefore, the object of the second and third aspects of the present invention is to prevent excessive heating of the non-sheet passing portion of the heating element regardless of the fixing method and the recording material supply method, and to prevent the heating element and the heating element. It is an object of the present invention to provide a fixing device capable of preventing the deterioration of the durable life, the deterioration of the fixing film and the pressure member, the unstable running of the fixing film, and the like due to the heat loss of the fixing film.

In order to solve the above-mentioned problem, when the heating amount of the heating element 1 is set to be larger than that of the non-sheet passing portion from the beginning of energization of the heating element 1, The following problems may occur.

That is, since a temperature difference occurs in the longitudinal direction of the heating element 1 from the start of energization until the recording material enters the fixing nip portion, the temperature difference also occurs in the fixing film 7 and the pressure roller 10 in the same direction. May occur, and the running of the fixing film 7 may be abnormal, or heating failure may occur at the edge of the recording material, resulting in deterioration of image quality.

Therefore, an object of the fourth aspect of the present invention is to provide a fixing device capable of eliminating the temperature difference in the longitudinal direction of the heating element and preventing the running abnormality of the fixing film and the heating failure of the end portion of the recording material. Especially.

Further, in the conventional SURF fixing method, when a branch electric path is provided to branch from the heating element, the heating element is in the fixing nip portion, so that heat is taken by both the fixing film and the pressure roller. Since the heat is taken only by the fixing film in the electric circuit, the temperature rises more severely than that of the heating element, and the following problems occur. That is, the fixing film is thermally damaged, and wrinkles are generated in the fixing film, and it is impossible to control the deviation. Further, cracks due to non-uniform temperature distribution of the heater substrate and breakage of the heating element and the branch circuit have occurred.

Therefore, the object of the fifth aspect of the invention is to prevent excessive temperature rise of the branch circuit to eliminate thermal damage to the fixing film and prevent cracking of the heater substrate and disconnection of the heating element and branch circuit. It is to provide a fixing device capable of performing the above.

By the way, for example, in order to shorten the time (start-up time) from the start of energization to reaching the controlled temperature (rise time), the width of the heating element must be narrowed, and after the controlled temperature is reached, it is favorable. In order to obtain fixability, the width of the heating element must be wide.

However, in the conventional SURF fixing method, since there is only one heating element, the conflicting requirements cannot be satisfied, and there is a problem that fixing failure tends to occur especially when copying at a low temperature. .

Therefore, an object of the sixth invention is to provide a fixing device capable of obtaining a good fixing property while shortening the rise time.

On the other hand, in the conventional method for supplying electric power to the heating body, as shown in FIG. 43, the electric power is supplied to the heating body in a short time from the state where the electric power is not supplied to the heating body, and the temperature of the heating body is changed. In order to rapidly raise the temperature to the temperature required for fixing, and to supply the maximum amount of electric power required in advance to the heating element in advance in order to improve the fixing of the first recording material.
There were the following problems.

That is, as shown in FIG. 41, the heating element 1 is
As described above, the resistance heating element 1b is screen-printed on the heater substrate 1a and the entire surface is covered with the glass coating layer 1c. Therefore, when a large electric power is applied to the heating element 1 at a time, the heating is performed. Since the thermal expansion coefficients of the constituent materials of the body 1 are different from each other, there arises a problem that the heating body 1 is deteriorated due to cracks in the glass coat layer 1c on the surface thereof and its life is shortened.

Therefore, the object of the seventh invention is to raise the temperature of the heating element to the optimum temperature for fixing in a short time to make the fixing of the first recording material satisfactory, but at the same time, to reduce the load on the heating element. It is an object of the present invention to provide a fixing device that can reduce the life of the heating element and realize a long life of the heating element.

By the way, in the conventional fixing device adopting the SURF fixing method, if an abnormality occurs in the running control of the fixing film, the fixing execution operation is immediately stopped, so that the following problems occur. It was

That is, while the recording material carrying the unfixed toner image is moving and passing through the fixing nip portion, the power supply to the heating body is turned off.
However, since the driving of the fixing film is stopped, the recording material remains in the fixing device, and unfixed toner adheres to the fixing film and the pressure roller when fixing the recording material to the outside of the fixing device. The film, the pressure roller, and the like are contaminated, causing offset, and lowering the durability of the fixing film, the pressure roller, and the like.

Therefore, the object of the eighth aspect of the invention is to eliminate the problem of stains due to unfixed toner on the fixing film, the pressure roller, etc. even when an abnormality occurs in the running drive control of the fixing film and to eliminate the offset. An object of the present invention is to provide a fixing device capable of preventing the occurrence of deterioration and the deterioration of durability of a fixing film and the like.

[0033]

In order to achieve the above object, the first invention is to bring a fixing film into contact with a heating body and move the fixing film, and to bring a recording material into close contact with the surface of the fixing film opposite to the heating body. In a fixing device for fixing an unfixed image on the recording material by moving the heating material along with the fixing film to a heating member position and applying heat energy from the heating member to the recording material through the fixing film, A resistance heating element having energizing electrodes at both ends in a direction orthogonal to the moving and passing direction of the recording material, a plurality of branch electric paths branched from the resistance heating element and arranged in parallel with the resistance heating element, and heat generation of the branch electric path. The feature is that it is configured to include a control means.

The second aspect of the invention is to detect the size of the first recording material and fix the second and subsequent recording materials when the same image is continuously fixed on a plurality of recording materials of the same size. In addition, the fixing device is provided with control means for controlling the heat distribution of the heating body according to the size of the recording material.

According to a third aspect of the invention, a fixing film is brought into contact with a heating body to move the fixing film, and a recording material is brought into close contact with the surface of the fixing film opposite to the heating body so that the recording material moves together with the fixing film at a position of the heating body. An apparatus for fixing an unfixed image on a recording material by applying heat energy to the recording material from a heating body via a fixing film, wherein the heating body is arranged in a direction orthogonal to a moving passage direction of the recording material. A fixing device including a resistance heating element having energizing electrodes at both ends thereof, and a branch electric path branched from at least one position in the middle of the resistance heating element along a longitudinal direction and selectively energized. When the recording material is moving and passing outside the fixing nip portion, only the resistance heating element of the heating element is energized for a predetermined time.

According to a fourth aspect of the invention, a fixing film is brought into contact with a heating body to move it, and a recording material is brought into close contact with the surface of the fixing film on the side opposite to the heating body, and this is moved along with the fixing film at the position of the heating body. A device for fixing an unfixed image on a recording material by applying heat energy to the recording material from a heating body via a fixing film, and having a plurality of dimensions in a direction orthogonal to the moving passage direction of the recording material. A heating member that can heat-treat a recording material, has a switching unit that changes the amount of heat generated by energization per unit length in the longitudinal direction of the heating member with respect to the longitudinal position of the heating member, and the recording material passes through the fixing nip portion. In a fixing device having a switching unit that changes the amount of heat generated by energization per unit length in the longitudinal direction of the heating body in accordance with the position in the longitudinal direction of the heating body, within a predetermined time from the start of energization of the heating body, Characterized by a substantially uniform over the heat-generating amount per longitudinal unit length of the heat element in the longitudinal direction heating the entire width of the heating body.

According to a fifth aspect of the present invention, a fixing film is brought into contact with a heating body to move the fixing film, and a recording material is brought into close contact with the surface of the fixing film opposite to the heating body so that the recording material moves together with the fixing film at a position of the heating body. An apparatus for fixing an unfixed image on a recording material by applying heat energy to the recording material from a heating body via a fixing film, wherein the heating body is arranged in a direction orthogonal to a moving passage direction of the recording material. A fixing device including a resistance heating element having energizing electrodes at both ends thereof, and a branch electric path branched from at least one position in the middle of the resistance heating element along a longitudinal direction and selectively energized. , Calorific value Q1 per unit length of the branch circuit
And the amount of heat generation Q2 per unit length of the resistance heating element on the non-sheet-passing side from the branch position of the branch electric path, the relationship of Q1 <Q2 is established.

According to a sixth aspect of the present invention, a fixing film is brought into contact with a heating body to move the fixing film, and a recording material is brought into close contact with the surface of the fixing film opposite to the heating body so that the recording material moves together with the fixing film at a position of the heating body. In a fixing device for fixing an unfixed image on a recording material by applying heat energy to the recording material from a heating body through a fixing film, the heating bodies are arranged in a direction orthogonal to a moving passage direction of the recording material. It is characterized by including a plurality of resistance heating elements arranged in parallel and a control means for selectively energizing the resistance heating elements.

According to a seventh aspect of the present invention, a fixing film is brought into contact with a heating body to move the fixing film, a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved together with the fixing film through a position of the heating body. In a fixing device for fixing an unfixed image on a recording material by applying heat energy to the recording material from a heating body through a fixing film, the electric power is not supplied to the heating body, and then gradually in a short time. It is characterized in that a means for increasing the electric power is provided.

In the eighth invention, the fixing film is brought into contact with the heating body to move the fixing film, and the recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved together with the fixing film through the position of the heating body. In a fixing device for fixing an unfixed image on a recording material by applying heat energy to a recording material from a heating body through the fixing film, when an abnormality occurs in running drive control of the fixing film, All the driving and energization of the fixing device are stopped after the recording material in (1) is discharged to the outside of the fixing device.

[0041]

According to the first aspect of the invention, since the temperature distribution in the longitudinal direction of the heating element is made uniform by the operation of the heat generation control means of the branch circuit, the temperature distribution of the heating element is made uniform, the film shift control by the temperature difference, and the heating element. It is possible to suppress excessive temperature rise of the non-sheet passing portion.

According to the second aspect of the invention, when the same image is continuously fixed on a plurality of recording materials of the same size, the second and subsequent recording materials are detected based on the detection of the size of the first recording material. Since the heat distribution of the heating element is controlled according to the size of the recording material during fixing, overheating of the non-sheet passing portion of the heating element is suppressed, and durability due to heat loss of the heating element and heating element It is possible to prevent a decrease in life, a decrease in durability of the fixing film and the pressing member, and an unstable running of the fixing film.

According to the third aspect of the invention, the temperature difference between the recording material passing area (paper passing portion) and the recording material non-passing area (non-paper passing portion) of the heating element can be suppressed to a small level, and the running property of the fixing film becomes unsatisfactory. Stabilization and overheating of the non-sheet passing portion of the heating element can be prevented.

According to the fourth aspect of the present invention, within a predetermined time from the start of energization to the heating element, the amount of heat generated by energization per unit length in the longitudinal direction of the heating element is substantially uniform over the entire heating width in the longitudinal direction of the heating element. Since it is made uniform, it is possible to prevent abnormal running of the fixing film and defective heating of the end portion of the recording material due to the temperature distribution in the longitudinal direction of the heating body.

According to the fifth aspect of the invention, excessive temperature rise of the branch circuit can be suppressed, thermal damage to the fixing film can be eliminated, and cracking of the heater substrate and breakage of the heating element and branch circuit can be prevented.

According to the sixth aspect of the invention, the plurality of heating elements are selectively energized and controlled, so that it is possible to obtain a good fixing property while shortening the rise time.

According to the seventh aspect of the invention, it is possible to raise the temperature of the heating element to the optimum temperature for fixing the recording material in a short time from the state in which no electric power is supplied to the heating element, and to fix the first recording material. The heating element can be made excellent, and further, the load applied to the heating element can be reduced to prolong the life of the heating element.

According to the eighth aspect of the invention, when an abnormality occurs in the running control of the fixing film, the recording material in the fixing device is discharged to the outside of the fixing device, and then all the driving and energization are stopped. The problem of contamination of unfixed toner such as the fixing film and the pressure roller does not occur, and occurrence of offset and deterioration of durability of the fixing film and the like can be prevented.

[0049]

【Example】

<First Invention> A first embodiment of the first invention will be described below with reference to FIGS. 1 is a control block diagram of the heating element, FIG. 2 is a configuration diagram of a fixing device according to the present invention, FIG. 3 is a sectional view of a fixing film, and FIG. 4 is a configuration diagram of an image forming apparatus.

First, an outline of the image forming apparatus will be described with reference to FIG. 4. After placing the original 119 on the fixed original glass 120 and setting predetermined copying conditions, when the copy start button is turned on, the photosensitive drum is turned on. 139 is rotationally driven in the direction of the arrow shown.

Further, the light source 121 and the first mirror 123 move forward along the lower surface of the original platen glass 120 from the home position on the left side in the drawing to the right side at a predetermined speed V, and the second and third mirrors 124, When 125 moves forward at a speed of V / 2, the downward image surface of the original 119 on the original glass 120 is illuminated and scanned from the left side to the right side in FIG. Imaging exposure (slit exposure) is performed on the surface of the photosensitive drum 139 via the imaging lens 129 and the fourth, fifth, and sixth fixed mirrors 126, 127, and 128.

Before the exposure, the surface of the photosensitive drum 139 is uniformly charged to a predetermined positive or negative potential by the primary charger 130, and the surface is exposed to the above exposure.
An electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the photosensitive drum 139. Then, the electrostatic latent image formed on the photosensitive drum 139 is developed by the developing device 131 and visualized as a toner image.

On the other hand, the recording material P is fed by a paper feeding means (not shown).
The recording material P is fed through the guide 133 to the transfer portion between the photosensitive drum 139 and the transfer charger 134 at a predetermined timing, and receives the transfer of the toner image on the photosensitive drum 139.

The recording material P, to which the toner image has been transferred, is sequentially separated from the surface of the photosensitive drum 139 by a separating means (not shown), and is discharged by the discharging needle 135 to remove the rear surface charges, and then the conveying portion 138 and the guide 118. Is introduced into the fixing device 60 according to the present invention, and the toner image is fixed by the fixing device 60, and then discharged to the outside of the apparatus.

The structure of the fixing device 60 according to the present invention will now be described with reference to FIG. 2. In FIG. 2, reference numeral 1 is a linear heating element having a low heat capacity, which is formed by a holder 2 having a high heat insulating property. It is supported. The holder 2 is made of a material having high heat insulation, heat resistance, and rigidity, such as PPS (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether ether ketone), and liquid crystal polymer. It is made of resin or a composite material of these resins and ceramics, metal, glass or the like.

A driving roller 8 and a tension roller 9 are rotatably arranged above the heating element 1. The driving roller 8 and the tension roller 9 and the heating element 1 have a thin endless belt-shaped fixing film. 7 is wound. The fixing film 7 has a thickness of 100 μm or less (preferably 40 μm) with high heat resistance, releasability and durability.
The following) is composed of a single layer or a composite layer film.

FIG. 3 shows the structure of the fixing film 7 made of a composite layer film. The fixing film 7 is releasable from the outer surface (the surface facing the toner image) of the heat-resistant layer 7a as the base layer (base film). It is configured by stacking layers 7b. Here, the heat-resistant layer 7a is, for example, PI (polyimide), PE.
EK (polyether ether ketone), PES (polyether sulfone), PEI (polyether imide),
A high heat resistant resin film such as PPA (polyparabanic acid), a metal foil such as Ni, SUS, Al, etc., and a film having excellent strength and heat resistance. Further, as the material of the release layer 7b, for example, a fluororesin such as PTFE (polytetrafluoroethylene), PFA, FEP, etc., a silicon resin, etc. are preferable. The resistance value of the surface of the fixing film 7 can be lowered by mixing the release layer 7b with a conductive agent such as carbon black, graphite, or conductive whiskers. The surface can be prevented from being charged. Also, the heat-resistant layer 7a
The release device 7b is formed by laminating a release layer film with adhesive, laminating the release layer material by electrostatic coating (coating), vapor deposition, stacking by a film forming technique such as CVD (Chemical Vapor Deposition), and a heat-resistant layer material. It can be performed by forming a two-layer film by co-extruding the release layer material.

By the way, the heating body 1 is provided with a pressure roller 1
0 is a total pressure of 4 to 7K with the fixing film 7 sandwiched between them.
A fixing nip portion is formed at a portion where the pressure roller 10 is brought into pressure contact with the heating body 1. The pressure roller 10 has a rubber elastic layer 12 made of a material having a high releasability such as silicon rubber. Direction).

The heating element 1 has a longitudinal direction in the direction orthogonal to the moving direction of the fixing film 7 (width direction of the fixing film 7).
Shown in.

That is, as shown in FIG. 1, the heating element 1 includes a resistance heating element 1b on a heater substrate 1a such as an alumina substrate and branch electric paths 1d, 1e, 1 branched from the resistance heating element 1b.
f and 1g are screen-printed, and a glass coat layer 1c is formed on the resistance heating element 1b and the branch electric paths 1d to 1g. The glass coat layer 1c is in contact with the fixing film 7 and has high insulation and slipperiness.

By the way, energizing electrodes 4a and 4d are provided at both ends of the resistance heating element 1b, and the branch electric circuit 1d is provided.
Electrodes 4b, 4c, 4e, 4f for energization at each end of ~ 1g
Are provided respectively. The electrode 4a is electrically connected to the heating body drive circuit 13 as shown in the figure,
The electrodes 4b to 4f are electrically connected to the heat generation control device 14. The heat generation control device 14 has a triac,
The amount of heat generated in the resistance heating element 1b and the branch electric circuits 1d to 1g is controlled by turning on / off the power supply at an arbitrary duty ratio.

Further, temperature sensors 5a and 5b are attached near both ends of the back surface of the heater substrate 1a (the surface opposite to the surface on which the resistance heating element 1b is provided), and the temperature sensors 5a and 5b are attached. As shown, it is connected to an MPU (microcomputer) 50. The temperature sensor 5
A low resistance thermometer such as a Pt film screen-printed on the heater substrate 1a, or a low heat capacity thermistor is used as a and 5b.

In addition, reference numeral 15 in FIG. 1 is an operation panel,
Reference numeral 16 is a memory, and 17 is a power supply.

The operation of the fixing device 60 will be described.

As shown in FIG. 2, the recording material P to which the toner image Ta has been transferred is guided by the guide 118 and introduced into the pressure contact portion (fixing nip portion) between the heating body 1 and the pressure roller 10. Then, the recording material P is sent in the direction of the arrow in the figure by the fixing film 7, and passes through the pressure contact portion between the heating body 1 and the pressure roller 10 while receiving a narrow pressure.

Then, the heating element 1 is energized and heated at a predetermined timing by the image formation start signal. That is, when the heating element drive circuit 13 shown in FIG. 1 is driven to supply electric power between the electrodes 4a and 4d, the resistance heating element 1b generates heat in its entire longitudinal width region. At this time, if the difference between the temperatures detected by the temperature sensors 5a and 5b is out of a certain specified range, the heating body drive circuit 13 is driven and an appropriate one is selected from the branch electric paths 1d to 1g. The amount of heat generation is controlled by the heat generation control device 14 so that the branch electric circuit (1d to 1g) is energized and the difference between the temperatures detected by the temperature sensors 5a and 5b falls within a predetermined specified range.

As a result, the temperature distribution in the longitudinal direction of the resistance heating element 1b is made uniform, and the recording material P passing through the pressure contact portion (fixing nip portion) between the heating element 1 and the pressure roller 10 is the heating element 1b.
The toner image Ta, which is applied with heat energy from the fixing film 7 through the fixing film 7 and is adhered to the lower surface of the fixing film 7, is uniformly heated in the width direction to be softened and melted, and is fixed uniformly on the recording material P as a permanent image. To be done. The branch duty paths (1d to 1g) and the energization duty ratio of the heat generation control device 14 selected at this time are related to the width of the recording material P, the temperature difference detected by the temperature sensors 5a and 5b, and the power supply amount. Properly determined.

By the way, the fixing film 7 has a property of being closer to the higher temperature, and when the difference between the temperatures detected by the temperature sensors 5a and 5b is within the specified range, the temperature difference is maintained, and The heating body drive circuit 13 is driven so that the temperature sensors 5a and 5b alternately detect the respective temperatures detected by the temperature sensors 5a and 5b, and the predetermined branch electrical paths (1d to 1g) are energized to cause the branch electrical paths. (1d
Heat generation is controlled by the heat generation control device 14 connected in series with respect to .about.1 g), and as a result, the film deviation control due to the temperature difference is properly performed.

On the other hand, when a recording material having a width smaller than the longitudinal width of the resistance heating element 1b is used, the portion of the heating element 1 where the recording material does not pass (non-sheet passing portion) is not absorbed by the recording material. However, in this embodiment, the temperature sensors 5a,
The heating body drive circuit 13 is driven in the same manner as described above so that the difference in temperature detected by 5b falls within the specified range, and the predetermined branch electric lines (1d to 1g) are energized, and the branch electric lines (1d to 1g). Since the heat generation amount is controlled by the heat generation control device 14 connected in series with the heating element 1, the temperature rise of the non-sheet passing portion of the heating element 1 can be suppressed, uniform fixing property can be obtained, and the heating element 1 and the resistance heating element 1b can be obtained. It is possible to prevent the durability life from being shortened due to the heat loss, the durability of the fixing film 7, the pressure roller 10 and the like, and the unstable running of the fixing film 7.

Next, a second embodiment of the first invention will be described with reference to FIG. FIG. 5 is a control block diagram of the heating element according to the second embodiment. In this figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In this embodiment, the branch circuits 1d, 1e, 1
f and 1g are arranged on both sides of the resistance heating element 1a in the sheet passing direction, and a variable resistor 6 (6a, 6b, 6c, 6d) is provided in place of the heat generation control device 14 in the first embodiment, and the variable resistance device is provided. 18 is energized.

Further, three temperature sensors 5a, 5b, 5c are provided on the back surface of the heater substrate 1a, and the temperature detected by the central temperature sensor 5a is used as a reference value, and the reference value and each of the temperature sensors 5b, 5c are detected. The amount of heat generation is controlled based on the difference from the temperature and each detected temperature. That is, the resistance variable device 18 changes the resistance value of the variable resistor 6 (6a, 6b, 6c, 6d) to control the heat generation amount so that the temperature distribution in the longitudinal direction of the resistance heating element 1b becomes uniform.

Therefore, in this embodiment as well, a uniform fixing property can be obtained, and the film deviation control due to the temperature difference, the non-sheet passing portion temperature of the heating element 1 and the like can be achieved.

The arrangements of the heat generation control device 14, the variable resistor 6, the variable resistance device 18, and the branch electric lines 1d to 1g in the above first and second embodiments can be arbitrarily selected.

Next, a third embodiment of the first invention will be described with reference to FIGS. 6 and 7. 6 is a control block diagram of the heating element according to the third embodiment, and FIG. 7 is a sectional view of the heating element.

In FIG. 6, 1e and 1f are resistance heating elements, and electrodes 4g and 4h are provided along the longitudinal direction thereof. Further, energization electrodes 4i and 4j are provided at both ends of one resistance heating element 1e, and an energization electrode 4k is provided at one end of the other resistance heating element 1f. , 4j, 4k are connected to each heating body drive circuit 13.

Further, the conductive member 20 is provided on the heater substrate 1a.
So that the electrodes 4g and 4h are electrically connected to each other,
4h is provided in contact with the conductive member 20,
The paper width sensor 19 detects the paper passing width, and the conductive member drive circuit 21 is driven based on this, and the wire 22 connected to the conductive member 20 moves in the longitudinal direction (left and right direction in FIG. 6).

By the way, in the heating element 1, as shown in FIG. 7, the film sliding side of the heater substrate 1a is covered with the glass coating layer 1c, and the resistance heating elements 1e, 1 are provided on the opposite side.
f, the electrodes 4g and 4h, the conductive member 20, and the wire 22 are provided.

When a voltage is applied to the energizing electrodes 4i, 4j, 4k, the resistance heating elements 1e, 1f generate a predetermined amount of heat, and this heat is generated from the heating element 1 to the heater substrate 1.
It is transferred to the fixing film 7 through a and the glass coat layer 1c and is used for fixing. Since the heater substrate 1a and the glass coat layer 1c are both extremely thin and have a small heat capacity,
The heat from the heating element 1 is transmitted to the fixing film 7 without a large time delay and loss.

Also in this embodiment, as in the second embodiment, three temperature sensors 5 are provided on the back surface of the heater substrate 1a.
a, 5b, 5c are provided, and the amount of heat generated based on the difference between the detected temperature of the central temperature sensor 5a as a reference value (reference temperature) and each detected temperature of the temperature sensors 5b, 5c, and each detected temperature. Is controlled. That is, the heat generation control device 12 changes the heat generation amount of the resistance heating elements 1e and 1f, and controls the heat generation amount so that the temperature distribution in the longitudinal direction of the resistance heating elements 1e and 1f becomes uniform.

Therefore, according to this embodiment, the same effect as that obtained in the first and second embodiments can be obtained. <Second Invention> Next, a first embodiment of the second invention will be described with reference to FIG.

FIG. 8 is a control block diagram of the heating element 1.
In the figure, 1a is a heater substrate, 1b is a resistance heating element, 1d,
Reference numerals 1e, 1f, and 1g denote branch electric paths branching from the resistance heating element 1b, and each branch electric path 1d to the back surface of the resistance heating element 1b.
Temperature sensors 5a, 5b, 5c, 5d at the branch point of 1g
Is attached. And each temperature sensor 5a-
5d is connected to the MPU 50.

The resistance heating element 1b and the branch circuit 1d are also provided.
Electrodes 4a, 4b, 4c, 4d, and 4e are provided to 1g, and these electrodes 4a to 4d are connected to each heating body drive circuit 13. In FIG. 8, 26 is a temperature sensor, 27 is a decoder, 15 is an operation panel, 16 is a memory, and 17 is a power supply.

Here, the control of the heating element 1 when the same image is continuously formed on a plurality of recording materials of the same size will be described.

When the start button on the operation panel 15 is pressed, a decode signal corresponding to the entire length of the heating element 1 is sent from the MPU 50 to the decoder 27, and the decoded signal corresponds to the heating element drive circuit corresponding to the entire length. Selectively drive III. Each heating element drive circuit 13 has one terminal connected to the energizing electrodes 4b to 4e, and the other terminal is shared and the electrode 4a of the resistance heating element 1b is connected via the power supply 17.
Wired to (common electrode). In this case, the resistance heating element 1
voltage is applied only between the electrodes 4a and 4f at both ends of b,
Therefore, only the resistance heating element 1b is energized, and the effective full-length area m (A3) of the resistance heating element 1b generates heat with a predetermined amount of heat generation per unit length, which is equal to the longitudinal width of the recording material supplied to the apparatus. The image fixing is executed without any trouble without depending on it.

When the first recording material passes through the heating element 1 of the fixing device, a part of the heat energy of the heating element 1 is absorbed by the recording material, and the temperature of the heating element 1 is increased by the passage of the recording material. Descends. Temperature sensors 5a, 5b, 5c, 5 at this time
The temperature detection signal of d is sent to the MPU 50. The temperature detection signal is the MPU in the order of the temperature sensors 5a, 5b, 5c and 5d.
A branch electric line branched from a branch point where the temperature sensor (5a to 5d) that is taken in by 50 and has a temperature signal that is substantially equal to the temperature control temperature of the heating element 1 among the four temperature detection signals is attached. (1d to 1g) is used as a branch electric path of the second and subsequent recording materials.

That is, when the recording material of the maximum size in the longitudinal direction is supplied, the temperature of the heating element 1 is lowered to the same extent over the entire longitudinal width by the passage of the recording material. Since the branch point is not found by the temperature detection method and the branch position detection method described above, the heating body drive circuit III is driven also for the second and subsequent recording materials, and only between the electrodes 4a and 4f at both ends of the heating element 1b. A voltage is applied, and only the heating element 1b is energized, so that the image fixing of the recording material of the maximum size in the longitudinal direction after the second sheet is executed without any trouble.

When a recording material whose longitudinal width is the same as that of the B4 plate sheet is supplied, the temperature of the heating element 1b in the portion of the longitudinal width K (B4) is lowered by the passage of the recording material. Since the temperature of the temperature sensor 5d does not drop due to the mounting positions of the temperature sensors 5a to 5d described above, the branch circuit is 1f according to the temperature detection method and the branch position detection method described above. A decode signal corresponding to this from the MPU 50 drives the heating body drive circuit IV and the heating body drive circuit III corresponding to the branch circuit 1f through the decoder 27 to drive the heating body drive circuit IV of the recording material passage portion k to a unit length. Heat is generated with a predetermined amount of heat generated per hit, and image fixing of the recording material supplied to the apparatus is executed without any trouble. The portion of the heating element 1b corresponding to the non-sheet passing portion (m−k) has an energization circuit configuration in parallel with the branch electric path 1f, and the amount of heat generation is small, and excessive temperature rise of the non-sheet passing portion of the heating element 1b is suppressed. .

The energization control of the heating element 1b when the recording material whose longitudinal width is the same as that of the A4 size sheet and the B5 size sheet is supplied is the same as that described above.

The energization control of the heating element 1b when the recording material is supplied so that the width in the longitudinal direction is the same as that of the smallest size paper that can be supplied to the image forming apparatus and used is the same as described above.

When an irregular-shaped recording material whose width in the longitudinal direction is not the longitudinal width of the standard paper is supplied, immediately after the first recording material passes through the heating element 1b of the fixing device, the above-mentioned temperature detecting method is used. And a suitable branch electric circuit (1d-1g) is found by the branch position detection method. As described above, if the width of the recording material in the longitudinal direction is within the usable range of the apparatus, image fixing of any irregular-shaped recording material can be performed without any trouble.

Next, as another embodiment, heating body control in the heat roller fixing system will be described.

FIG. 9 is a block diagram of a heating control circuit of another embodiment. In this embodiment, a heating body control circuit is incorporated in a heat roller fixing system which is a conventional technique. Two heating bodies 33 and 34 are provided inside the heating roller 32. The one heating element 33 is a fixed heating element, and the other heating element 34 is a moving heating element.

Further, in FIG. 9, 5a, 5b, 5c, 5
Reference numeral d denotes a temperature sensor, which is attached to the outside of the heating roller 32, and the attachment position of these in the longitudinal direction is the same as in the case of the first embodiment.

FIG. 10 shows a heating roller 32 and a pressure roller 35.
The pressure roller 35 is pressed against the heating roller 32 and is driven to rotate.

Before the start button on the operation panel 15 is pressed, the fixed heating element 33 and the movable heating element 34 are shown in FIG.
The heat roller 32 is located at the position indicated by (3) and generates heat over the entire length m of the heating roller 32 with a heat generation amount that does not hinder image fixing. Then, when the start button of the operation panel 15 is pressed, the image fixing is executed without depending on the longitudinal width of the recording material supplied to the apparatus.

The first recording material is the heating roller 3 of the fixing device.
2 and the pressure roller 35, the heating elements 33, 34
Part of the heat energy supplied from the heating roller 32 to the heating roller 32 is taken by the recording material, and the temperature of the surface of the heating roller 32 drops as the recording material passes.

By the way, the temperature sensors 5a, 5b, 5
As shown in FIG. 10, c and 5d are mounted at positions where the temperature change of the heating roller 32 immediately after the contact with the recording material and the distance from the recording material can be measured. The temperature detection signals of these temperature sensors 5a to 5d are sent to the MPU 50. Then, the temperature detection signals are M in the order of 5a, 5b, 5c, 5d.
The position where the temperature sensor (5a to 5d) that is taken in by the PU 50 and has a temperature signal that is substantially equal to the temperature control temperature of the heating roller 32 among the four temperature detection signals is attached is the longitudinal direction of the recording material. Be the edge.

When the recording material of the maximum size in the longitudinal direction is supplied, the surface temperature of the heating roller 32 is lowered to the same extent over the entire longitudinal width by the passage of the recording material. Since the edge of the recording material is not found by the temperature detection method and the recording material edge detection method described above, the recording material is heated in the same way as the first recording material after the second recording material, and the maximum size recording in the longitudinal direction of the second recording material is performed. The image fixing of the material is executed without any trouble.

When a recording material whose longitudinal width is the same as that of the B4 plate sheet is supplied, the surface temperature of the longitudinal width K of the heating roller 32 is lowered by the passage of the recording material. Since the temperature sensors 5a to 5d are mounted in the same manner as in the embodiment, the temperature of the position of the temperature sensor 5d does not drop due to this mounting position. Therefore, the movable heating element 34 is moved as shown in FIG. 11 by the above-mentioned temperature detecting method. As a result, only the recording material passage portion k is heated, so that the image fixing of the recording material supplied to the apparatus is executed without any trouble. Then, since the portion of the heating roller 32 corresponding to the recording material non-passing portion (mk) is not heated, its excessive temperature rise is suppressed.

The positions of the heating elements 33 and 34 when the recording material whose longitudinal width is the same as that of the A4 size sheet and the B5 size sheet respectively are supplied are shown in FIGS. 12 and 13, respectively. The heat control of 32 is also the same as described above.

When a recording material is supplied whose longitudinal width is the same as that of the smallest size paper that can be supplied to the image forming apparatus and used, the heating roller 32 is the fixed heating element 33.
The movable heating element 34 is heated only by itself and does not generate heat.
As a result, heating is performed in the longitudinal direction by a width of h, and image fixing is performed without any trouble. In this case, since the recording material non-passing portion (m-h) of the heating roller 32 does not generate heat, its excessive temperature rise is suppressed.

When an irregular-shaped recording material is supplied in which the longitudinal width of the recording material is not the longitudinal width of the standard paper, immediately after the first recording material passes through the heating roller 32 of the fixing device, the above-mentioned temperature detecting method is used. A suitable moving position of the movable heating element 34 is found by. As described above, if the width of the recording material in the longitudinal direction is within the usable range of the apparatus, image fixing of any irregular-shaped recording material can be performed without any trouble.

The movable heater 34 is provided with a small motor (not shown) at its right end so that the movable heater 34 can move in the heating roller 32 in the longitudinal direction in accordance with the longitudinal width of the recording material supplied. The small motor is driven by a heating body movement signal which is linked with the heating body energization signal from the MPU 50.

Next, FIG. 14 shows a third embodiment of the second invention.

In this embodiment, the five heating elements 36a, 36b, 36c, 36d, 36e corresponding to the lengths h (minimum), i (B5), j (A4) and m (A3), respectively.
Is inserted in the center of the heating roller 32.

Therefore, the temperature detecting sensors 5a, 5 described above are used.
Only one heating element (36a to 36e) is energized via each heating element drive circuit by the temperature detecting method and the recording material edge detecting method by b, 5c and 5d. In this embodiment, a small motor for moving the heating elements 36a to 36e is not required, and the structure can be simplified. <Third Invention> Next, an embodiment of the third invention will be described with reference to the accompanying drawings.

The present invention energizes only the resistance heating element of the heating element for a predetermined time when the recording material is moving and passing outside the fixing nip portion. FIG. 15 shows the heating according to the first embodiment. FIG. 16 is a diagram showing the surface of the body, and FIG. 16 is a diagram showing the energization sequence and the change over time in the temperature of the heating body.

Here, the energization sequence when the recording material size is the B5 plate and two sheets are continuously copied will be described.

After the start of copying, the fixing device starts driving, and at the same time, the resistance heating element 1b is energized. The temperature of the paper-passing area and the non-paper-passing area of the heating element 1 rises from T0 = 25 ° C,
Immediately after reaching T2 = 200 ° C. (controlled temperature), the first recording material plunges into the fixing nip portion. At the same time, by energizing the branch circuit 1d corresponding to the B5 plate, the temperature of the non-sheet passing area of the heating element 1 is lowered to T1 = 190 ° C. When the sensor (not shown) detects that the trailing edge of the first recording material comes out of the fixing nip portion, the branch circuit 1b is turned off.

The temperature of the non-sheet passing area of the heating element 1 rises again, and T2 is reached before the second recording material enters the fixing nip portion.
become. Further, when the branch current 1d is turned on at the same time when the second recording material plunges into the fixing nip portion, the temperature of the non-sheet passing area of the heating element 1 drops to T1 and the trailing edge of the recording material comes out of the fixing nip portion. At the same time, the power supply to the heating element 1b and the branch circuit 1d are both turned off.

According to the above, the difference between the temperature of the paper-passing area and the temperature of the non-paper-passing area of the heating element 1 can be suppressed within about 10 ° C. even during continuous copying of small-sized paper, and the heating element It is also possible to prevent abnormal temperature rise in the non-sheet passing area of No. 1.

Next, a second embodiment will be described with reference to FIGS. 17 and 18. Note that FIG. 17 is a surface view of the heating body according to the second embodiment, and FIG. 18 is a diagram showing an energization sequence and a temporal change of the heating body temperature at that time.

In this embodiment, energization to the heating element 1b and the branch circuit 1d is controlled by the temperature detected by the temperature sensors 5a and 5b shown in FIG.

That is, during the fixing execution operation, the difference between the temperature T2 detected by the temperature sensor 5a in the recording material passing region (paper passing portion) and the temperature T1 detected by the temperature sensor 5b in the non-paper passing region is ΔT> 10 ° C. When the detected temperature becomes T2 = T1, the energization of only the heating element 1b is switched to the energization of the branch energization 1d. With this configuration, the temperature difference between the paper passing area and the non-paper passing area of the heating element 1 can be suppressed within about 10 ° C., and the abnormal temperature rise in the non-paper passing area can be prevented.

In addition, although the third embodiment is shown in FIG. 19, in this embodiment, the energization of the heating element 1b and the branch circuit 1d is switched depending on the number of copies.

That is, after the start of copying, when the sensor (not shown) detects that the odd numbered recording material comes out of the fixing nip portion, the energization is switched to the branch circuit 1d. When the even numbered recording material comes out of the fixing nip portion, only the heat is generated 1b. By doing so, the same effect as described above can be obtained. <Fourth Invention> Next, an embodiment of the fourth invention will be described with reference to the accompanying drawings.

FIG. 20 is a view obtained by combining the view of the heating element 1 as seen from the sliding surface side with the film and the energization control circuit block diagram of the heating element 1.

In FIG. 20, 1b is a resistance heating element formed on the lower surface of the heater substrate 1a of the heating element 1 which is a film sliding surface, and 1d, 1e and 1f are branched from predetermined positions in the middle of the heating element 1b. It is also a first, second, and third branch electric circuit. In the case of the present embodiment, each of the branch electric circuits 1d to 1f is set to have the same material, the same thickness, and the same width as the heating element 1b. The heating element 1b is formed in a straight line along the length of the heater substrate 1a at the substantially central portion of the lower surface of the heater substrate 1a. Reference numerals 4a and 4b denote energizing electrodes (input terminals) made of a good conductive material such as Ag provided at the left end portion and the right end portion of the heating element 1b.

K is the effective total length area of the heating element 1b between the electrodes 4a and 4b. In the case of this embodiment, the maximum size recording material that can be supplied to the apparatus and used is the A3 size and corresponds to its width. It is set to a linear dimension.

Further, in the present embodiment, recording materials of various sizes are supplied on the basis of the so-called one-sided reference, which is based on the base line a on the left end side of the heating element 1b, and the first branch circuit 1d and the second branch circuit 1 are provided.
e, the third branch electric circuit 1f is from the base line a to h,
It is branched from the heating element 1b at a distance position of i and j, and each free end portion is formed to extend to a position corresponding to the right end portion of the heating element 1b or an outer position thereof.

Here, each distance h, i, j is set to a length dimension corresponding to the width of the B5 plate, A4 plate and B4 plate in the case of this embodiment.

4d, 4e and 4f are branch electric lines 1d and 1
It is an energizing electrode (input terminal) made of a good conductive material such as Ag provided at the free ends of e and 1f.

The temperature sensor 5 is arranged on the upper surface side of the heater substrate 1a, that is, on the side opposite to the side on which the heating element 1b and the like are provided, and in the area h which is the minimum sheet passing area.

Further, in FIG. 20, reference numeral 15 is an operation panel of the image forming apparatus, and as shown in FIG. 21, a power switch 15a, a copy number setting key 15b, a number indicator 15c, a recording material size designation. An operation key (size selection key) 15d, a copy start key 15e, etc. are arranged.

Thus, after the image forming apparatus starts the image forming operation by the image forming start signal, the fixing film starts to run and the heating element 1 is energized at a predetermined timing.

Now, the energization control of the heating element 1 will be described with reference to FIG. Note that FIG. 22 is a timing chart of the operation of the fixing device.

At time t0, the power switch 1 of the image forming apparatus
It is assumed that 5a is turned on. After that, at time t1, the user specifies the recording material size to be used with the size selection key 15d (here, B, for example, A4 size (210 mm
(Width) is specified), the size information of the A4 width is fetched by the MPU 50. When the user specifies the number of copies (here, n copies, where n ≧ 2) with the copy count setting key 15b at time t2, the copy count information is also fetched in the MPU 14.

After that, at time t3, the copy start key 1
When 5e is pressed, at the same time when the image forming operation is started,
The rotation driving of the fixing film is also started. At the same time t3,
The heating element drive circuit I starts driving, and a predetermined voltage E is applied between the electrodes 4a and 4b at both ends of the heating element 1b.

On the other hand, at the same time t3, another heating body drive circuit
The driving is stopped in II to IV, the first to third branch electric circuits 1d, 1e, 1f are kept in the open state, only the heating element 1b is in the energized state, and the effective total length region k of the heating element 1b is k. Rapidly starts to increase the temperature substantially uniformly in the longitudinal direction.

At time t4, A shorter than the effective total length by h
Although the recording material of four widths rushes into the fixing nip portion, the heating element 1 has risen to a predetermined fixing temperature by time t4.

From the start of energization at time t3 to time t4 when the recording material enters the fixing nip portion, the temperature of the heating member 1 in the longitudinal direction is uniform, so that the fixing film, the driving roller,
The temperature of the tension roller (driven roller) in the axial direction becomes uniform, and the running of the fixing film is stable without causing meandering or the like. The recording material stays in the fixing nip portion from time t4 to time t5, and during this period, the effective entire length area h of the heating element 1 uniformly generates heat, so that good fixing property can be obtained over the entire width direction of the recording material. However, a so-called non-sheet-passing portion temperature rise occurs in a region (non-sheet-passing region) where the recording material does not pass within the effective total length region h of the heating element 1, but the time (t4 -t5) is a time of 2 to several seconds. Therefore, the temperature rise is small, the parts such as the heating element 1 are not damaged, and there is no problem in running the fixing film.

After completion of the fixing process of the first recording material, time t
The end of the fixing operation of the first recording material is detected by a paper discharge sensor (not shown) arranged on the paper discharge roller side of the fixing device 6, and the detection signal is taken into the MPU 50.
Then, at the same time, a decode signal corresponding to the paper size information (A4 size: 210 mm width) taken into the MPU 50 at time t1 is sent to the decoder 27, and the decoded signal corresponds to the heating drive circuit I corresponding to the specified size width. Same as III
To drive. Then, the heating element 1b and the second branch circuit 1
The energization system for e is closed, and the portion of the heating element 1 in the area i corresponding to the sheet passing area of the A4 size recording material generates a predetermined amount of heat per unit length, so that the image fixing of the A4 size recording material is performed. It is executed without any problems.

On the other hand, the portion of the heating element 1b corresponding to the non-sheet passing portion (ki), that is, the heating element 1b from the branch point of the second branch circuit 1e to the electrode 4b on the other end side of the heating element 1b. Since the portion has a current-carrying circuit configuration in parallel with the second branch electric circuit 1e and a current is shunted to both, the heat generation amount per unit length of the heating element 1b portion is smaller than that of the heating element 1b portion of the paper passing portion i. Also becomes smaller. Further, the sum of the heat generation amount per unit length of the heating element 1b portion and the second branch electric path 1e is smaller than that of the heating element 1b portion of the paper passing portion i.

Such branch energization was performed from time t6 to time t7 when the second recording material enters the fixing nip portion. The slight increase in temperature generated in the non-sheet passing portion (ki) during the fixing operation of the first recording material is offset. Time t
At 7, the second A4 size recording material plunges into the fixing nip portion, but since the heating element drive circuits I and III are driven continuously, heat is generated in the portion corresponding to the non-sheet passing portion (ki). The amount becomes smaller than the sheet passing portion i, and as a result, the non-sheet passing portion (k−
Excessive temperature rise of the heating element 1b portion of i) is prevented.

On the other hand, from the time t3 to the time t6, since the entire heat generating area k is uniformly heated, even if the heat generation of the heating element 1b sheet passing portion (ki) is decreased from the time t6,
During the fixing process of the second recording material, the surface temperature of the heating element 1 at the position corresponding to the paper edge on the branch point side of the second branch electric path 1e of the A4 width recording material is changed from the area i to the heating element 1b. Range (k-
It does not excessively decrease due to heat transfer to i), and good fixability can be obtained on the second recording material.

Similarly to the second recording material, the third recording material,
After the fixing operation for the n-th recording material is performed, when the completion of the fixing operation for the n-th recording material is detected by the paper discharge sensor (not shown) at time t11, the heating body drive circuits I and III Is turned off to stop energizing the heating element 1. Then, the fixing film is idled for a predetermined time in a non-heated state for the purpose of heat dissipation, and then stopped at time t12. Then, after a lapse of a predetermined time, the power switch 15a is automatically turned off.

When the recording material size designated at time t1 is other than the A4 width (210 mm width), the following points are changed as compared with the above sequence.

For B5 width (182 mm width) recording material: At time t6, the heating element drive circuit IV is driven instead of the heating element drive circuit III. As a result, the energization system for the first branch electric circuit 1d is closed, and the excessive temperature rise in the region (kh) is prevented by the same mechanism as in the case of the A4 size.

When a recording material having a B4 width (257 mm width):
At time t6, the heating body drive circuit II is driven instead of the heating body drive circuit III, and the excessive temperature rise in the region (k-j) is prevented.

When the recording material has an A3 width (297 mm width): The heater driving circuits II, III, IV are always turned off, and A
Good fixability is obtained from the first sheet to the n-th sheet of the 3rd printing material, and excessive temperature rise in the non-sheet passing portion does not occur.

Now, a comparative example will be described with reference to FIG.

FIG. 23 is a timing chart showing a comparative example, and it is assumed that A4 size is designated at time t1 as shown in the figure.

At time t3 when the copy start key 15e is turned on, the heating element drive circuits I and III are simultaneously turned on.

Time t4 when the recording material enters the fixing nip portion.
By this time, the region (ki) of the heating element 1 has a lower temperature than the region i. Therefore, a temperature difference in the axial direction also occurs in the fixing film and the driving roller. Then, by the time t4, the running of the fixing film is affected by the temperature distribution in the longitudinal direction of each member and becomes defective. Specifically, the fixing film is displaced from the longitudinal region (ki) on the surface of the heating element 1b in the direction of the region i.

Further, since the heat is dissipated from the area i to the area (ki) from the time t3 to t4, the temperature of the end area of the area i forming the boundary with the area (hi) is lowered and the first sheet is There is a possibility that the fixing property at the position in the longitudinal direction corresponding to the above end area of the recording material may deteriorate.

If the number of copies set by the user is sufficiently large, the running abnormality of the fixing film due to the above mechanism is immediately corrected, but if the user makes a single copy continuously (no second and subsequent sheets in the timing chart). Then, the fixing film may be displaced from the area (hi) toward the area i, and the fixing film may be damaged.

FIG. 24 is a timing chart showing the third embodiment.

In the first embodiment, the energization of the branch circuit 1e (drive of the heating element drive circuit III) is started at time t6 when the end of the fixing operation of the first recording material is detected, but in the present embodiment, The heating body drive circuit III is driven from time t4 when the recording material enters the fixing nip portion. Thus, according to this embodiment, since branch current is supplied during the first sheet passing, the temperature rise in the sheet passing portion of the first heating element 1 is smaller than that in the first embodiment. Further, since the entire heat generating area is uniformly heated before the first recording material enters the fixing nip portion, the initial fixing film running abnormality and the end fixing failure of the first recording material do not occur.

Here, a modification of the heating element 1 is shown in FIG. In FIG. 25, 1a is a heater substrate such as an alumina substrate, and 1f and 1g are heating elements having effective heating lengths k and i corresponding to A3 width and A4 width, respectively. An electrode 4a is provided at the left end of the heating element 1, and the heating element 1f,
Electrodes 4b and 4c are provided at the right end of 1g, respectively. The heating element drive circuits k and i are connected to the electrodes 4b and 4c, respectively.

FIG. 26 shows a timing chart according to the fourth embodiment.

In this embodiment, instead of providing a branch electric path, a plurality of heating elements (without a branch electric path) according to the usable paper passing size are provided.

Until the fixing operation for the first sheet of recording material is completed, the heating element of the maximum size (here, the heating element 1f) is caused to generate heat by turning on the heating element drive circuit k. When the end of the fixing operation of the recording material is detected, the heating body drive circuit k is turned off, and the heating body 1g corresponding to the recording material size to be used (here, A4 size) is driven at the substantially same time. When the circuit i is turned on, heat is generated.

In the first embodiment, the heat radiation at the branch end of the branch electric circuit is large, and there is a possibility that a defective fixing may locally occur.
In this embodiment, since there is no branch circuit, uniform and good fixing property can be obtained. <Fifth Invention> Next, an embodiment of the fifth invention will be described with reference to the accompanying drawings.

FIG. 27 is a partial surface view of the heating element according to the first embodiment. In this embodiment, the heating element 1 made of the same material and having the same thickness is used.
b and branch electric lines 1d, 1e, 1f, 1g are provided, the width of the heating element 1b is 1.5 mm, and each branch electric line 1d-1
The width of g is set to 3.0 mm.

Therefore, the resistance value per unit length of each branch electric line 1d to 1g is twice that of the heating element 1b, and the heat generation amount Q1 per unit length of the branch electric lines 1d to 1g and its branching position. The following equation is used between the heat generation amount Q2 per unit length of the non-sheet-passing side heating element 1b:

[0157]

## EQU1 ## The relationship of Q1 <Q2 is established. Therefore, excessive temperature rise of the branch electric paths 1d to 1g is suppressed, thermal damage to the fixing film is eliminated, and cracking of the heater substrate 1a and breakage of the heating element 1b and the branch electric paths 1d to 1g are prevented. A second embodiment is shown in FIG. 28. In this embodiment, the heating element 1b and the branch circuit 1 are provided.
The width and thickness of d, 1e, 1f and 1g were set to the same,
Resistance value of branch circuit 1d-1g (1.5 × 10 -4 Ω ・ c
m) is the resistance value of the heating element 1b (3.0 × 10 −4 Ω · cm)
Thus, the heat generation amount Q1 per unit length of the branch electric circuits 1d to 1g is smaller than the heat generation amount Q2 per unit length of the heating element 1b on the non-sheet passing side from the branch position (Q1 <
Q2) I keep it down.

Further, FIG. 29 shows a third embodiment. Incidentally, FIG.
9 is a cross-sectional view of the heating element 1.

In this embodiment, the heating element 1b and the branch circuit 1
The materials of d, 1e, 1f, and 1g are set to have the same width, but the thickness of the branch electric circuits 1d to 1g (20 μm) is set to be twice the thickness of the heating element 1b (10 μm), thereby branching. The heat generation amount Q1 per unit length of the electric paths 1d to 1g is suppressed to be smaller (Q1 <Q2) than the heat generation amount Q2 per unit length of the heating element 1b on the non-sheet passing side from the branch position.

Thus, the same effects as those of the first embodiment can be obtained in the second and third embodiments described above. <Sixth Invention> Next, the sixth invention will be described with reference to the accompanying drawings.

FIG. 30 is a front view of the heating element 1 according to the first embodiment of the sixth invention. In this embodiment, two heating elements 1A having the same material, the same thickness and the same width (1.5 mm) are used. , 1B are arranged in parallel with each other in the length direction with a gap of 1.5 mm therebetween.

At the start of energization, an electric current is applied between the electrodes A and B to rapidly raise the temperature of one of the heating elements 1A, and a temperature sensor (not shown) in contact with the back surface of the heating element 1A side is used. After the detected temperature reaches a predetermined controlled temperature, electrodes BC
The energization is also started during this period, and both heating elements 1A and 1B are maintained at a predetermined controlled temperature.

Based on the above, it is possible to shorten the rise time of the heating element 1 and to obtain good fixability after the rise.

FIG. 31 shows the second embodiment of the sixth invention.
In the present embodiment, one of the two heating elements 1A and 1B arranged at intervals of 1.0 mm in parallel to the longitudinal direction has a width of 2.0 mm, and the other 1B has a width of 1.0 mm. ing.

Thus, at the start of energization, electricity is applied between the electrodes C'and D ', the temperature of the heating element 1 is rapidly raised, and after the heating element 1 reaches the controlled temperature, the electrodes A'- Energize between B '.
By doing so, the rise time of the heating element 1 can be shortened and good fixing properties can be obtained.

By the way, in this embodiment, the heating elements 1A and 1B may be selectively energized depending on the temperature of the heating element 1 before energization.

That is, FIG. 32 shows the relationship between the rising time and the heating body temperature at each energization.
3. Let T0 be the time for the recording material to enter the fixing device. When the temperature T of the heating element 1 is T0≤T <T1, the electrode C'-
When energized and started up during D ', the heating element 1 is heated to the controlled temperature in a time less than T0. After that, the electrode A'-
By energizing between B ', sufficient fixability can be obtained.

When the temperature T of the heating element 1 is T1≤T <T2, the same good fixing property can be obtained by energizing the electrodes A'-B 'to start them up.

Further, when the temperature T of the heating element 1 is T2≤T, electricity is applied between the electrodes A'-B 'and C'-D'. Also in this case, good fixability can be obtained.

Next, a third embodiment of the sixth invention is shown in FIG.

FIG. 33 is a surface view of the heating element 1. In this embodiment also, the two heating elements 1A and 1B are arranged in parallel in the longitudinal direction at appropriate intervals, but one energized heat is generated. Body 1A has a width of 20 m at the center and both ends.
m, 3.0 mm, and the other electric heating element 1
B has the same width of 1.5 mm.

At the start of energization, the electrodes C "-D" are energized to rapidly start the heating element 1 and, after the heating element 1 reaches the controlled temperature, between the electrodes A'and B '. By also energizing the heating element 1, the rise time of the heating element 1 can be shortened, good fixing properties can be obtained, and abnormal temperature rise in the non-sheet passing area of the heating element 1 can be prevented. <Seventh Invention> Next, an embodiment of the seventh invention will be described with reference to the accompanying drawings.

FIG. 34 is a graph best showing the characteristics of the sequence according to the first embodiment of the present invention, and shows the relationship between the supplied power and the time and the temperature change of the heating body with it.

Electric power is supplied to the heating body at the same time when the switch is turned on. At this time, the necessary and maximum electric power preset for the heating body is divided into two stages from the state in which the electric power is not supplied to the heating body. Supply.

As described above, the load applied to the resistance heating element is reduced, and the fixability becomes good without the need for a very long time to reach the controlled temperature of the heating element.

The input voltage switching time is set according to conditions such as the time required for the heating element to reach the optimum temperature and the fixing property. In FIG. 34, the preset required and maximum power input to the heating element is 1000 W, and the optimum temperature for fixing the heating element is 200 ° C. This value is for reference only, and is optimal depending on the configuration of the fixing device. You can select the value. The sequence from the start of fixing the first recording material to the end of fixing is the same as the conventional example.

Next, a second embodiment of the seventh invention will be described with reference to FIG.

FIG. 35 is a graph best representing the characteristics of the sequence according to the second embodiment, showing the relationship between the supplied power and time and the temperature change.

Electric power is supplied to the heating element 1 at the same time when the switch is turned on. At this time, the heating element is not supplied with electric power, and the necessary and maximum electric power preset for the heating element is set in several steps. Supply separately. FIG. 35 shows an example in which electric power is supplied in three stages. The amount of electric power at each stage and the time for supplying the electric power at this time are determined from the fixing property conditions and the like.

Thus, according to this embodiment, the resistance heating element 1
The load applied to b is reduced, and the fixability is also improved without significantly increasing the time for reaching the optimum temperature of the heating element 1.

Note that in FIG. 35, the preset required and maximum electric power input to the heating element is 1000 W, and the optimum temperature for fixing the heating element is 200 ° C. This value is a reference value, and the fixing value is fixed. The optimum value can be selected depending on the device configuration. The sequence from the start of fixing the first recording material to the end of fixing is the same as the conventional example.

FIG. 36 shows a third embodiment of the seventh invention.

FIG. 36 is a graph best showing the features of the sequence of this embodiment and shows the relationship between the power supplied to the heating element and the time and the temperature change of the heating element.

Electric power is supplied to the heating body at the same time when the switch is turned on. At this time, the heating body is continuously supplied with the necessary and maximum electric power preset from the state in which the electric power is not supplied. Supply steplessly. The relationship between the time and the amount of electric power at this time is determined by conditions such as fixability. Incidentally, FIG.
6 shows the case where the relationship between time and electric energy is not linear.

Thus, also in this embodiment, the load on the resistance heating element caused by applying a large amount of electric power to the resistance heating element at one time is reduced, and the time required to reach the optimum temperature of the heating element is very long. The fixing property is also improved.

In FIG. 36, the preset required and maximum electric power input to the heating element is 1000 W, and the optimum temperature for fixing the heating element is 200 ° C. This value is a reference value. The optimum value can be selected depending on the device configuration. The sequence from the start of fixing the first recording material to the end of fixing is the same as the conventional example. <Eighth Invention> Next, an embodiment of the eighth invention will be described with reference to the accompanying drawings.

FIG. 37 is a diagram showing a sequence of the fixing device according to the present invention. As shown in FIG. 37, in this embodiment, if the fixing film being driven and driven exceeds the control range for some reason, the fixing is performed. Stop all drive of the equipment and energization of heating elements.

That is, first, the operations other than the fixing device are stopped,
Next, after the recording material is discharged to the outside of the fixing device by a sensor (not shown), the heating body is turned off, the driving roller is stopped at the same time, and the rotation of the fixing film is stopped. That is, the recording material is discharged to the outside of the fixing device after all the unfixed toner images are fixed, thereby preventing the unfixed toner from adhering to the fixing film or the pressure roller.

Next, a second embodiment of the eighth invention will be described with reference to FIG. Note that FIG. 38 is a side view of the fixing device 60.

In this embodiment, when an abnormality occurs in the drive control of the fixing film 7, if a sensor (not shown) detects that the leading edge of the recording material P enters the paper discharge roller 149, the heating element is heated. 1 is turned off to stop the driving of the fixing film 7, and the pressure roller 10 is moved in the direction of the arrow (downward) to release the pressure on the recording material P, and only the paper discharge roller 149 is driven. By doing so, the recording material P carrying the unfixed toner image Ta is discharged to the outside of the fixing device 60. Therefore, when the unfixed toner image Ta carried on the recording material P passes through the fixing nip portion, the problem that the unfixed toner adheres to the fixing film 7 and the pressure roller 10 and contaminates them is solved.

Further, FIG. 39 shows a third embodiment of the eighth invention.

FIG. 39 is a side view of the fixing device 60. In this embodiment, when an abnormality occurs in the driving control of the fixing film 7, the heating body 1 is turned off and the fixing film 7 is driven. After stopping, the rotation of the drive roller 8 is reversed (in the direction of the arrow in the drawing) by a clutch (not shown). Therefore, according to the present embodiment, the recording material P carrying the unfixed toner image Ta can be discharged from the fixing device 60 to the paper feeding side, and the same effects as those of the first and second embodiments can be obtained. .

[0193]

As is apparent from the above description, according to the first aspect of the invention, the temperature distribution in the longitudinal direction of the heating element is made uniform by the action of the heat generation control means of the branch circuit, so that the temperature distribution of the heating element is made uniform. It is possible to control the film deviation due to the temperature difference, control the excessive temperature rise of the non-sheet passing portion of the heating element, and the like.

According to the second aspect of the invention, when the same image is continuously fixed on a plurality of recording materials of the same size, the recording materials of the second and subsequent recording materials are detected based on the detection of the size of the first recording material. Since the heat distribution of the heating element is controlled according to the size of the recording material during fixing, overheating of the non-sheet passing part of the heating element is controlled, and durability due to heat loss of the heating element and heating element is controlled. It is possible to prevent a decrease in life, a decrease in durability of the fixing film and the pressing member, and an unstable running of the fixing film.

According to the third aspect of the invention, the temperature difference between the recording material passing area (paper passing portion) and the recording material non-passing area (non-paper passing portion) of the heating element can be suppressed to a small level, and the running property of the fixing film is impaired. The stabilization and the temperature rise of the non-sheet passing portion of the heating element are prevented.

According to the fourth invention, the amount of heat generated by energization per unit length in the longitudinal direction of the heating body is constant over the entire heating width in the longitudinal direction of the heating body within a predetermined time from the start of energization of the heating body. Since it is made substantially uniform, it is possible to prevent abnormal running of the fixing film and defective heating of the end portion of the recording material due to the temperature distribution in the longitudinal direction of the heating body.

According to the fifth aspect of the present invention, the temperature rise of the branch circuit is suppressed, thermal damage to the fixing film is eliminated, and cracking of the heater substrate and breakage of the heating element and branch circuit are prevented.

According to the sixth aspect of the present invention, the plurality of heating elements are selectively energized and controlled, so that good fixing property can be obtained while shortening the rise time.

According to the seventh aspect of the present invention, the heating element can be heated to the optimum temperature for fixing the recording material in a short time from the state where the heating element is not supplied with electric power, and the first recording material can be fixed. The heating element can be made excellent, and further, the load applied to the heating element can be reduced to prolong the life of the heating element.

According to the eighth aspect of the invention, when an abnormality occurs in the running control of the fixing film, the recording material in the fixing device is discharged to the outside of the fixing device, and then all the driving and energization are stopped. The problem of contamination of unfixed toner such as the fixing film and the pressure roller does not occur, and occurrence of offset and deterioration of durability of the fixing film and the like can be prevented.

[Brief description of drawings]

FIG. 1 is a control block diagram of a heating body according to a first embodiment of the first invention.

FIG. 2 is a configuration diagram of a fixing device according to the present invention.

FIG. 3 is a sectional view of a fixing film.

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

FIG. 5 is a control block diagram of a heating body according to a second embodiment of the first invention.

FIG. 6 is a control block diagram of a heating body according to a third embodiment of the first invention.

FIG. 7 is a sectional view of a heating body according to a third embodiment of the first invention.

FIG. 8 is a control block diagram of the heating body according to the first embodiment of the second invention.

FIG. 9 is a control block diagram of a heating body according to a second embodiment of the second invention.

FIG. 10 is a configuration diagram of a heating roller and a pressure roller.

FIG. 11 is a position diagram of a movable heating body corresponding to a B4 plate recording material.

FIG. 12 is a position diagram of a movable heating body corresponding to an A4 size recording material.

FIG. 13 is a position diagram of a movable heating body corresponding to a B5 plate recording material.

FIG. 14 is a cross-sectional view showing a state in which five heating bodies having different lengths are incorporated in a heating roller.

FIG. 15 is a surface view of a heating body according to the first embodiment of the third invention.

FIG. 16 is a diagram showing an energization sequence according to the first embodiment of the third aspect of the invention and changes in the heating body temperature at that time.

FIG. 17 is a surface view of a heating body according to a second embodiment of the third invention.

FIG. 18 is a diagram showing a change in heating body temperature in the second embodiment of the third invention.

FIG. 19 is a diagram showing changes in heating body temperature in the third embodiment of the third invention.

FIG. 20 is a combined view of a configuration diagram of a heating body according to the first embodiment of the fourth invention and a block diagram of an energization control circuit for the heating body.

FIG. 21 is a configuration diagram of an operation panel.

FIG. 22 is a timing chart showing the operation of the fixing device according to the first example of the fourth invention.

FIG. 23 is a timing chart according to a comparative example.

FIG. 24 is a timing chart showing the operation of the fixing device according to the third embodiment of the fourth invention.

FIG. 25 is a control block diagram of a heating body according to a fourth example of the fourth invention.

FIG. 26 is a timing chart showing the operation of the fixing device according to the fourth embodiment of the fourth invention.

FIG. 27 is a partial surface view of the heating body according to the first example of the fifth invention.

FIG. 28 is a partial surface view of a heating body according to the second embodiment of the fifth invention.

FIG. 29 is a partial surface view of a heating body according to a third embodiment of the fifth invention.

FIG. 30 is a surface view of a heating body according to the first example of the sixth invention.

FIG. 31 is a front view of a heating body according to a second embodiment of the sixth invention.

FIG. 32 is a diagram showing the relationship between the rising time and the heating body temperature during energization in the second embodiment of the sixth invention.

FIG. 33 is a front view of a heating body according to a third embodiment of the sixth invention.

FIG. 34 is a sequence diagram according to the first example of the seventh invention, and is a graph showing the relationship between the supplied power and the temperature change of the heating body.

FIG. 35 is a sequence diagram according to the second embodiment of the seventh invention, and is a graph showing the relationship between the supplied power and the heating body temperature change.

FIG. 36 is a sequence diagram according to the third embodiment of the seventh aspect of the invention and is a graph showing the relationship between the supplied power and the heating body temperature change.

FIG. 37 is a view showing a sequence of the fixing device according to the eighth invention.

FIG. 38 is a side view of the fixing device according to the second embodiment of the eighth invention.

FIG. 39 is a side view of the fixing device according to the third embodiment of the eighth invention.

FIG. 40 is a configuration diagram of a conventional fixing device.

FIG. 41 is a cross-sectional view of a heating body in a conventional fixing device.

FIG. 42 is a diagram showing temperatures of a sheet passing portion and a non-sheet passing portion of a heating body (heating roller).

FIG. 43 is a sequence diagram showing a conventional method for supplying electric power to a heating body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 heating body 1a heater substrate 1b resistance heating element 1c glass coat layer 1d-1g energizing electrodes 5a-5d temperature sensor 6 variable resistor 7 fixing film 8 drive roller 9 tension roller 10 pressure roller 13 heating body drive circuit 14 heat generation control Device 15 Operation panel 16 Memory 17 Power supply 18 Resistance variable device 19 Paper width sensor 20 Conductive member 21 Conductive member drive circuit 50 MPU (microcomputer) 60 Fixing device P Recording material

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kensaku Soka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (14)

[Claims] 1. A fixing film is brought into contact with a heating body to move the fixing film, and a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved together with the fixing film at a position of the heating body to move the heating body. In the fixing device for fixing the unfixed image on the recording material by applying heat energy to the recording material through the fixing film, the heating element is energized to both ends in the direction orthogonal to the moving passage direction of the recording material. A fixing device comprising: a resistance heating element having a working electrode; a plurality of branch electric paths branched from the resistance heating element and arranged in parallel with the resistance heating element; and heat generation control means for the branch electric path. . 2. The fixing device according to claim 1, wherein the heating element has a control unit that controls the temperature distribution in the longitudinal direction of the heating element according to the position in the longitudinal direction of the fixing film. 3. A fixing film is brought into contact with a heating body to move the fixing film, a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved together with the fixing film through a position of the heating body to move the heating body. In a fixing device for fixing an unfixed image on a recording material by applying heat energy to the recording material through a fixing film, when the same image is continuously fixed on a plurality of recording materials of the same size, A control means is provided for detecting the size of the second recording material and controlling the heat distribution of the heating body according to the size of the recording material when fixing the second and subsequent recording materials. Fixing device. 4. A fixing film is brought into contact with a heating body to move the fixing film, a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved through the fixing body together with the fixing film to move the heating body. Is a device for fixing an unfixed image on a recording material by applying heat energy to the recording material via a fixing film, wherein the heating element is provided at both ends in a direction orthogonal to the moving passage direction of the recording material. A recording material comprising a resistance heating element having a current-carrying electrode, and a branching circuit branched from at least one of the middle portions of the resistance heating element along the longitudinal direction and selectively controlled to be electrified. The fixing device is characterized in that when the sheet is moving outside the fixing nip portion, only the resistance heating element of the heating element is energized for a predetermined time. 5. A fixing film is brought into contact with a heating body to move the fixing film, a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved through the fixing body together with the fixing film to move the heating body. Is a device for fixing an unfixed image on a recording material by applying heat energy to the recording material through a fixing film from a recording material having a plurality of dimensions in a direction orthogonal to the moving passage direction of the recording material. The heating member is capable of being heat-treated, and has switching means for changing the amount of heat generated by energization per unit length in the longitudinal direction of the heating member with respect to the position in the longitudinal direction of the heating member. In a fixing device having a switching means for changing the amount of heat generated by energization per unit length in the longitudinal direction of the heating body depending on the position, the length of the heating body is changed within a predetermined time from the start of energization of the heating body. A fixing device, wherein the amount of heat generated by energization per unit length in the direction is made substantially uniform over the entire heating width in the longitudinal direction of the heating element. 6. The amount of heat generated by energization per unit length in the longitudinal direction of the heating member is increased from the start of energization of the heating member until the first recording material passes through the fixing nip portion. 6. The fixing device according to claim 5, wherein the fixing device is made substantially uniform over the entire heat generation width in the longitudinal direction of the body. 7. The amount of heat generated by energization per unit length in the longitudinal direction of the heating member is heated from the start of energization of the heating member until the first recording material enters the fixing nip portion. 6. The fixing device according to claim 5, wherein the fixing device is made substantially uniform over the entire heat generation width in the longitudinal direction of the body. 8. The heating element comprises: a resistance heating element having energizing electrodes at both ends thereof in a direction orthogonal to the moving direction of the recording material; and at least one position in the middle of the resistance heating element along the longitudinal direction. 8. A branch electric circuit that branches and is selectively energized and controlled to be energized.
The fixing device described. 9. A heating member is brought into contact with a fixing film to move the fixing film, and a recording material is brought into close contact with a surface of the fixing film opposite to the heating member, and the recording material is moved and passed together with the fixing film at a position of the heating member. Is a device for fixing an unfixed image on a recording material by applying heat energy to the recording material via a fixing film, wherein the heating element is provided at both ends in a direction orthogonal to the moving passage direction of the recording material. A fixing device including a resistance heating element having a current-carrying electrode and a branch electric path branching from at least one of midpoints along the longitudinal direction of the resistance heating element to selectively control energization. The relationship of Q1 <Q2 is established between the heat generation amount Q1 per unit length of the electric circuit and the heat generation amount Q2 of the resistance heating element on the non-sheet passing side from the branch position of the branch electric circuit. Characterizing Chakusochi. 10. A heating element is brought into contact with a fixing film to move it, and a recording material is brought into close contact with the surface of the fixing film opposite to the heating element, and the recording material is moved together with the fixing film through the heating element position to move the heating element. In the fixing device for fixing the unfixed image on the recording material by applying heat energy to the recording material through the fixing film, the heating elements are arranged parallel to each other in the direction orthogonal to the moving passage direction of the recording material. The fixing device is configured to include a plurality of resistance heating elements and a control unit for selectively energizing the resistance heating elements. 11. A heating element is brought into contact with a fixing film to move it, and a recording material is brought into close contact with the surface of the fixing film on the side opposite to the heating element, and the recording material is moved together with the fixing film through the position of the heating element. In a fixing device for fixing an unfixed image on a recording material by applying heat energy to the recording material through a fixing film, the electric power is gradually increased in a short time from the state in which the electric power is not supplied to the heating body. A fixing device comprising means for carrying out. 12. The fixing device according to claim 11, wherein the electric power is supplied to the heating element in a short time, and then the electric power is increased in several steps in a short time. 13. The fixing device according to claim 11, wherein a continuous stepless increase in electric power is carried out from a state where electric power is not supplied to the heating element. 14. A fixing film is brought into contact with a heating body to move the fixing film, a recording material is brought into close contact with the surface of the fixing film opposite to the heating body, and the recording material is moved and passed together with the fixing film at a position of the heating body. In a fixing device for fixing an unfixed image on the recording material by applying heat energy to the recording material via the fixing film from the fixing film, when the traveling drive control of the fixing film is abnormal, the fixing device is in the fixing device. A fixing device characterized by stopping all driving and energization after discharging the recording material to the outside.