JPH09197838A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive image forming device having high image quality capable of efficiently performing transfer and simultaneous fixing and shortening warm-up time, and also excellently obtaining a recorded image at high speed by avoiding the influence of heat exerted on a process after fixing. SOLUTION: In this image forming device, an unfixed toner image formed on an electrostatic latent image carrier 11 is transferred on a sheet from the image carrier 11 and simultaneously fixed so as to obtain the recorded image; an induction coil 3 for making the image carrier 11 generate an induced current so as to generate heat is provided near the transfer part of the image carrier 11. A roller 60 coming in contact with the image carrier 11 and consisting of a heat pipe is provided on the downstream side of the transfer part of the image carrier 11.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, conventionally, an unfixed toner image on an image carrier is transferred to a recording medium and the transferred toner image is fixed. There is known a technique in which a heating lamp is arranged at the same time to perform the heating at the same time. According to this device, the transfer efficiency is improved and the device can be downsized.

However, in the case of the above apparatus, the heat generated from the heating lamp diffuses to the surroundings and adversely affects each process and peripheral parts, so that a good image cannot be obtained and the durability of the parts is also deteriorated. There was a problem. Furthermore, since the heating lamp, which is a heat source, and the heated portion are separated from each other by heating using radiant heat, it takes a relatively long time to warm up the fixing portion to reach a predetermined temperature suitable for fixing. It takes time, and during that time, the user cannot use the image recording device such as a copying machine and is forced to stand by for a long time. On the other hand, if a large amount of electric power is applied and heated in order to shorten the warm-up time and improve the operability of the user, the power consumption increases, which not only saves energy but also adversely affects the surroundings. Furthermore, there was a problem that it could be further encouraged.

Therefore, as disclosed in Japanese Patent Laid-Open No. 5-303248, the electrostatic latent image carrier is formed in a belt shape, and the side of the recording layer on which the toner image is formed is opposite to the side where the recording medium passes. In addition to providing a heating layer with a conductive layer sandwiched between
A method has been proposed in which an electrode is applied to the heating layer and a current is passed between the conductive layer and the electrode to directly heat only the transfer portion. Further, as disclosed in Japanese Patent Laid-Open No. 6-95518, a method has been proposed in which a heating resistor is slid or slid or rotated on the inside of the belt, that is, on the opposite side through which the recording medium passes.

[0005]

However, in the above-mentioned conventional image forming apparatus, the aim is to efficiently heat only the transfer portion. However, in practice, the electrodes and the heating resistors are provided to some extent. Since it has a heat capacity of 1, the warm-up that is commensurate with this heat capacity is indispensable, and the heat generated at an angle is released to the electrodes and the heat generating resistor, thus wasting energy. Further, since the electrodes and the heating resistors are pressed against each other to be electrically heated, the life is shortened due to abrasion and the like, and uniform heating cannot always be obtained, which may impair the image quality. further,
When the heat generating layer is formed on the electrostatic latent image carrier, the number of manufacturing steps is increased and the product cost is increased.

Further, after the electrostatic latent image carrier is heated to transfer and fix the toner image on the recording medium, heat remains on the electrostatic latent image carrier, so that when the next process is started again, This heat may hinder image formation. Therefore, in order to avoid this, there is a problem that the length of the electrostatic latent image bearing member in the process direction must be lengthened or the speed of the image forming process must be slowed down in order to naturally allow time for cooling. Still not resolved.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to enable efficient transfer and simultaneous fixing, and a reduction in warm-up time. An object of the present invention is to provide an image forming apparatus of high image quality at a cost, and to provide an image forming apparatus capable of obtaining a recorded image at high speed and satisfactorily while avoiding the influence of heat on the process after fixing. It is in.

[0008]

The present invention for achieving the above object is specified as follows for each claim. According to a first aspect of the invention, in the image forming apparatus, an unfixed toner image formed on an image carrier is transferred from the image carrier to a recording medium and simultaneously fixed to obtain a recorded image. It is characterized in that an induction coil is provided near the transfer portion of the body so as to generate an induction current in the image carrier and generate heat.
In the invention thus specified, the image bearing member directly self-heats due to electromagnetic induction, so that the electric-heat conversion efficiency is remarkably improved, and at the same time, it has a heat capacity such as an electrode and a heating resistor. Since heat does not escape to the object, the warm-up time can be shortened. Therefore,
The generated heat is released and the energy is not wasted, and energy can be saved.

According to a second aspect of the invention, in the image forming apparatus according to the first aspect, the image carrier has a magnetic metal layer. In the invention specified in this way, since the magnetic flux density absorbed by the image carrier becomes high, heat is easily generated.

According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the image carrier is pressed against the image carrier at a position downstream of a position where heat is generated by the induction coil. It is characterized in that a pressurizing member is provided. In the invention specified in this way, it becomes possible to perform the heat pressure fixing without directly applying pressure to the heating portion,
For example, it is preferable to use a flexible belt-shaped image carrier.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, a core is provided in the vicinity of the induction coil to collect and pass the magnetic flux generated by the induction coil. To do. In the invention thus specified, the heating efficiency by electromagnetic induction is improved.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the image carrier is a flexible belt. In the invention thus specified, the induction coil width can be easily widened and the nip width can be increased, so that not only the time for heating the recording medium itself but also the time for heating the toner is increased. Since it becomes longer, the fixing temperature can be set lower, and the thermal influence on other processes is reduced.

According to a sixth aspect of the invention, in the image forming apparatus, the unfixed toner image formed on the image carrier is transferred from the image carrier to a recording medium and simultaneously fixed to obtain a recorded image, A roller formed of a heat pipe that is in contact with the image carrier is provided on the downstream side of the transfer unit of the image carrier. In the invention specified in this way, the roller can rapidly absorb the unnecessary heat of the image carrier to further reduce the thermal influence on other processes, and at the same time, in the main scanning direction ( Since the temperature unevenness in the roller axial direction) can be eliminated and the heat can be made uniform, the image quality is improved.

According to a seventh aspect of the invention, in the image forming apparatus according to the sixth aspect, there is provided cooling means for cooling the end portion of the roller. In the invention thus specified, a sufficient cooling effect can be obtained even when heat is accumulated by printing for a long time, and unnecessary heat of the image carrier is absorbed more rapidly. It

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic sectional view of an image forming apparatus according to Embodiment 1 of the present invention.

The image forming apparatus shown in FIG. 1 has an electrostatic latent image carrier 10 as an image carrier which is rotationally driven, and has a charging means 20, a latent image writing means 30, a developing means 40 and a transfer fixing means 50. Are sequentially arranged along the peripheral surface of the electrostatic latent image carrier 10 as shown in the drawing, and each of them is responsible for each process of image formation. This image forming apparatus transfers an unfixed toner image generated by developing an electrostatic latent image on the electrostatic latent image carrier 10 from the electrostatic latent image carrier 10 to a sheet S as a recording medium. In addition, the recording image is obtained by simultaneously fixing.

In the first embodiment, the electrostatic latent image carrier 1
0 has a drum shape, and has a two-layer structure in which a conductive layer is formed on the inner surface side and a recording layer is formed on the outer side thereof. However, it is also possible to have a multilayer structure including these.

The conductive layer is formed by a transfer fixing means 50 described later.
Is a layer that is induction-heated by the coil 3 and is made of a metal such as aluminum, nickel, iron, copper, or an alloy thereof, but it is more preferable to use a magnetic metal such as iron or stainless steel. Here, the magnetic metal generally refers to one having a relative magnetic permeability of about 100 or more, and the larger the relative magnetic permeability, the higher the magnetic flux density absorbed and the more likely it is to generate heat.

The recording layer is a layer on which an unfixed toner image is formed, and is made of a dielectric material such as polyimide, but it is required to have heat resistance against the temperature at the time of fixing. Further, on the outer surface, a heat-resistant release layer is formed of a fluororesin such as polytetrafluoroethylene (PTFE), silicon rubber or the like to improve the separability from the sheet S as a recording medium.

The electrostatic latent image carrier 10 has bearing portions formed at both ends thereof and is rotatably attached to the main body frame so that it can be rotationally driven in the direction of arrow a in the figure by a drive source such as a motor. (Neither is shown).

The charging means 20 is for uniformly charging the surface of the recording layer of the electrostatic latent image carrier 10 to a predetermined electric potential, and the latent image writing means 30 is the above-mentioned by ion projection according to image information. The electrostatic potential of the recording layer is controlled to form an electrostatic latent image.

The developing means 40 develops the electrostatic latent image on the recording layer of the electrostatic latent image carrier 10 with toner.
As a result, an unfixed toner image which is a visible image is formed on the recording layer.

In the present embodiment, particularly, the transfer fixing means 50
Has a coil assembly 1 and a pressure roller 2, and is provided on the downstream side of the position where the developing means 40 of the electrostatic latent image carrier 10 is provided. The coil assembly 1 includes an induction coil 3 and a core 4 arranged in the vicinity of the coil 3, that is, the induction coil 3 includes the electrostatic latent image carrier 1.
It will be arranged in the vicinity of the 0 transfer portion.

The coil 3 is made of a heat-resistant copper wire which is wound in alignment with and laminated on a bobbin (not shown) having a heat-resistant insulation property. By passing an alternating current through the coil 3, the electrostatic latent image carrier 10 is formed. It is possible to generate an induction current and generate an alternating magnetic flux to generate heat. That is, the conductive layer of the electrostatic latent image carrier 10 is partially induction-heated by the coil 3. In this case, it is desirable that the conductive layer be as thin as possible. Since the heat capacity naturally increases when there is a thickness, the energy required for heating increases, and further, heat conduction occurs in the front-back direction (circumferential direction) of the electrostatic latent image carrier 10, and unnecessary parts are also present. Because it will be heated.

On the other hand, the core 4 for allowing the magnetic flux to efficiently pass through a desired position is made of a ferromagnetic material such as ferrite, which can increase the heating efficiency. In addition, it is also possible to adopt a configuration in which the arrangement of the core 4 is omitted.

The coil assembly 1 is disposed inside the drum-shaped electrostatic latent image carrier 10 with a gap of a predetermined dimension between the coil assembly 1 and the inner surface of the electrostatic latent image carrier 10.
This slight gap can prevent the current of the coil 3 from flowing through the conductive layer, and also prevent the heat of the electrostatic latent image carrier 10 from escaping by conduction. In the case of the air gap as in the present embodiment, the thermal insulating effect is large, so that only the electrostatic latent image carrier 10 is heated and the heating efficiency is maximized.

The pressure roller 2 is provided so as to be in pressure contact with the electrostatic latent image carrier 10 and is driven to rotate as the electrostatic latent image carrier 10 rotates. A silicon rubber layer 6 which is a surface-releasing heat-resistant rubber layer is formed around the shaft core 5 of the pressure roller 2.

Thus, the thermal energy generated by the induction heating of the conductive layer of the electrostatic latent image carrier 10 and the pressure contact of the pressure roller 2 to the electrostatic latent image carrier 10 generate it on the electrostatic latent image carrier 10. The formed unfixed toner image is transferred to the sheet S which is a recording medium and is simultaneously fixed.

In the first embodiment, when a high-frequency current obtained by inverting a commercial power source (not shown) is applied to the coil 3 of the coil assembly 1 of the transfer / fixing means 50 (here, the high frequency is a frequency of several kHz or more). This means that a high-frequency induced magnetic flux is alternately directed toward the conductive layer of the electrostatic latent image carrier 10, and the electrostatic latent image carrier 10 is partially heated by eddy current loss and hysteresis loss. As a result, the toner forming the unfixed toner image generated on the electrostatic latent image carrier 10 is melted, and the sheet S conveyed from the right side in FIG. By passing between the pressure roller 2 and the pressure roller 2 which are pressed against each other, the toner image is pressure-transferred thereon, and is completely fixed by applying heat and pressure.

As described above, according to the first embodiment, since the conductive layer of the electrostatic latent image carrier 10 directly generates heat by electromagnetic induction, the electric-heat conversion efficiency is significantly improved, and
Since heat does not escape to those having a heat capacity such as electrodes and heating resistors as in the conventional case, the warm-up time can be shortened. Therefore, the generated heat is dissipated and the energy is not wasted, and energy can be saved.

Further, the electrostatic latent image carrier 10 does not need to be provided with a layer made of a heat generating resistor as in the conventional case, and it is sufficient if at least a conductive layer and a recording layer are provided.
Low cost and high reliability.

Further, since the conductive layer of the electrostatic latent image carrier 10 can be heated by the induction coil 3 in a non-contact manner, no abrasion occurs and the life is long, and uniform heating is always obtained and the image quality is good. Become.

In addition, since the metal layer normally possessed by the electrostatic latent image carrier 10 can be used as a member to be heated, it is not necessary to separately provide a metal roller for induction heating.

On the other hand, the effect of simultaneous transfer and fixing of the unfixed toner image on the electrostatic latent image carrier 10 on the sheet S is achieved, in which the transfer efficiency is improved and the apparatus is downsized. Of course, you can

FIG. 2 is a schematic sectional view of an image forming apparatus according to a second embodiment of the present invention. Members common to those shown in FIG. 1 are designated by the same reference numerals, and their description will be omitted. Further, in FIG. 2, the charging unit 20, the latent image writing unit 30, and the developing unit 40 are not shown.

The second embodiment differs from the first embodiment in that a belt group 70 is used instead of the pressure roller 2 of the first embodiment. The belt group 70 has an endless belt 71 and rollers 72 and 73 on which the belt 71 is stretched. The belt 71 is made of a non-magnetic elastic member having surface releasability and heat resistance. .
According to the second embodiment, the same effect as that of the first embodiment can be obtained. In addition, the use of the belt 71 as described above has an advantage that the distance in the sheet conveying direction (hereinafter, referred to as a nip width) of the nip portion for sandwiching the sheet can be increased as compared with the method using the pressure roller. Therefore, the time for heating the sheet as the recording medium is increased, and the fixing temperature can be set low, so that the thermal influence on other processes can be reduced.

FIG. 3 is a schematic sectional view of an image forming apparatus according to a third embodiment of the present invention. Members common to those shown in FIG. 1 are designated by the same reference numerals, and their description will be omitted.

In the third embodiment, the exposure means 31 is used in place of the latent image writing means 30 of the first embodiment, and based on the difference in the electrostatic latent image generating means. The recording layer of the electrostatic latent image carrier 11 is different from that of the first embodiment in that it is composed of a photoconductor.

The exposure means 31 is composed of an illumination optical system and produces an optical image corresponding to image information by the electrostatic latent image carrier 11.
An electrostatic latent image is generated by irradiating the surface with the light and releasing the surface charge of the recording layer formed of the photoconductor. Even if the electrostatic latent image is generated by exposure as in the third embodiment, the same effect as in the first embodiment can be obtained.

Further, particularly in the third embodiment, the inner surface of the electrostatic latent image carrier 11 is contacted with the heat pipe on the downstream side of the position where the transfer fixing means 50 of the electrostatic latent image carrier 11 is provided. A roller 60 is provided. As is well known, heat pipes contain a working fluid inside a depressurized pipe, and when one is heated, the working fluid becomes vapor and flows to the other, where it dissipates heat and becomes a liquid. It applies the principle of transmitting heat from the heating part to the heat dissipation part by repeating the action of returning to.

Therefore, according to the third embodiment,
By rapidly absorbing the unnecessary heat of the electrostatic latent image carrier 11 by the roller 60, the thermal influence on other processes can be further reduced, and the temperature in the main scanning direction (axial direction of the roller 60) can be reduced. Since it is possible to eliminate unevenness and to make it uniform thermally, it is preferable for use when image quality is improved and particularly high-speed printing is required. The roller 6
0 is not limited to the heat pipe, and may be a roller made of a good heat conductive material such as copper or aluminum.

FIG. 4 is a schematic sectional view of an image forming apparatus according to a fourth embodiment of the present invention. Members common to those shown in FIG. 1 are designated by the same reference numerals, and their description will be omitted.

In the fourth embodiment, the electrostatic latent image carrier 1
This is different from the first embodiment in that an endless belt is used for 2 and a belt group 75 is used instead of the pressure roller 2.

The electrostatic latent image carrier 12 has a recording layer formed on the outside of a conductive layer made of a thin metal having flexibility, and the coil assembly 1 can be housed inside the recording layer. There is. This coil assembly 1
It is arranged so as to be separated from the inner surface of the electrostatic latent image carrier 12 by a certain distance. As a result, the space can be effectively used, the apparatus can be downsized, and the electrostatic latent image carrier 12 can serve as an electromagnetic shield. Moreover, the degree of freedom in designing the coil assembly 1 is increased, and the coil assembly 1 can be easily installed.

The coil assembly 1 is fixed to the frame body side (not shown). The electrostatic latent image carrier 12 is transported in the direction of the arrow in the figure by a roller 13 provided with a driving force from the machine body by a gear (not shown). The roller 60 is composed of a heat pipe having the same function as in the third embodiment.

Further, with respect to the outer surface of the electrostatic latent image carrier 12,
Belt group 75 so as to face the coil assembly 1
Is arranged. The belt group 75 is an endless belt 76.
And rollers 77 and 78 on which the belt 76 is stretched. The belt 76 is made of a non-magnetic elastic member having surface releasability and heat resistance. The roller 77 is disposed so as to be pressed against the roller 13 via a belt, and rotates synchronously in the opposite direction to the roller 13. On the other hand, the roller 78 is arranged so as to contact the roller 14 via the belt.

The high-frequency current flowing through the coil 3 generates a magnetic flux indicated by an arrow in the figure, and an induction current is generated in the conductive layer of the electrostatic latent image carrier 12 by electromagnetic induction, so that the conductive layer itself generates heat. The sheet S fed and conveyed by the paper feed roller 80 from the right side in FIG. 4 is the electrostatic latent image carrier 1.
2 and roller 1 pressed against each other via belt 76
By passing between the roller 4 and the roller 78, the toner image is partially pressure-transferred thereon. It is also possible to slightly separate the roller 14 and the roller 78 so that transfer is not performed between these rollers.

Next, the sheet S is an electrostatic latent image carrier 12
The toner is heated between the electrostatic latent image carrier 12 and the belt 76 while being sandwiched between the electrostatic latent image carrier 12 and the belt 76, and then the toner is exchanged via the electrostatic latent image carrier 12 and the belt 76. The pressure caused by passing between the roller 13 and the roller 77, which are pressed against each other, and the heat of the electrostatic latent image carrier 12 are applied to complete the transfer and fixing. Transferring from the electrostatic latent image carrier to the recording medium and simultaneously fixing in the present invention includes the case where the transfer is performed a little earlier than the fixing as described above.

As described above, in the case of the fourth embodiment in which the belt-shaped electrostatic latent image carrier 12 is used, it is not possible to directly press the heated portion sufficiently, but the roller is provided downstream of the heated portion. By arranging the pairs 13 and 77, the heat pressure contact fixing can be realized, and the same effect as that of the first embodiment can be obtained. In addition, by forming the electrostatic latent image carrier 12 into a belt shape, it is easy to widen the induction coil width of the coil assembly 1 and the nip width can be increased, so that the sheet itself, which is a recording medium, is heated. Not only the time becomes longer, but also the time for heating the toner becomes longer, so that the fixing temperature can be set lower, and the thermal influence on other processes can be further reduced.

The belt 76 can be made of a flexible metal member having surface releasability and heat resistance. By doing so, the belt 76 can also be formed by the high frequency current flowing through the coil 3. Since heat is generated, the heat fixing effect is enhanced.

FIG. 5 is a schematic sectional view of an image forming apparatus according to Embodiment 5 of the present invention, and FIG. 6 is a view seen from the left side of FIG. 5, which is common to the members shown in FIGS. 1 and 4. The same reference numerals are given to the members to be described, and the description thereof will be omitted.

The fifth embodiment differs from the fourth embodiment in that the pressure roller 2 is used instead of the belt group 75. Further, a transport guide 85 made of a metal member is arranged on the outer surface of the electrostatic latent image carrier 12 so as to face the coil assembly 1. Transport guide 85
Is induction-heated by the high-frequency current passed through the coil 3, so that the conveyed sheet S can be preheated in combination with the heat generation of the electrostatic latent image carrier 12. However,
It is also possible to configure the transport guide 85 with a member that does not generate heat by electromagnetic induction.

In this case, in the sheet S, the toner forming the unfixed toner image formed on the recording layer of the electrostatic latent image carrier 12 is melted, and the sheet S is preheated. By passing between the roller 13 and the pressure roller 2 which are pressed against each other via the electrostatic latent image carrier 12, the toner image is pressure-transferred thereon, and the electrostatic latent image carrier 12 is The heat and pressure that it has is applied to fully set it. Therefore, thermal pressure contact fixing can be realized more easily with a compact and low-cost configuration, and the same effect as that of the above-described fourth embodiment can be obtained.

An insulating material having a small thermal conductivity is interposed between the coil assembly 1 and the electrostatic latent image carrier 12.
It is also possible to provide the pressure roller 2 so as to be in pressure contact with the insulator fixed to the body frame with the electrostatic latent image carrier 12 interposed therebetween. If you do this,
It is possible to reduce the number of parts and realize more simple, low cost and miniaturization.

In the fifth embodiment, in particular, as shown in FIG. 6, a heat radiating fin 62 as a cooling means is provided at the end of the roller 60 formed of a heat pipe having the same function as in the third embodiment. ing. By doing so, a sufficient cooling effect can be obtained even when heat is accumulated by printing for a long time, and unnecessary heat of the electrostatic latent image carrier 12 can be absorbed more rapidly. Therefore, the thermal effect on other processes can be further reduced. Furthermore, it is possible to provide a fan 86 as a cooling means for forcibly cooling the end portion of the roller 60 by air or a water circulation means (not shown) for water cooling.

In this case, needless to say, it is not necessary to intentionally cool the process if it is naturally air-cooled sufficiently before entering the next process or can withstand a certain amount of heat. In addition, the roller 60 is not limited to the heat pipe, and may be a roller made of a good heat conductive material such as copper or aluminum.
Is the same as

The present invention is not limited to the above-described embodiments, but can be variously modified within the scope of the claims. For example, in the above-described embodiment, the toner image formed on the recording layer made of a dielectric or a photoconductor is transferred and simultaneously fixed. However, in this case, a conductive magnetic toner is used as the toner. It can also be used and can be applied to an image forming apparatus of a system in which a conductive magnetic toner is used to directly generate a toner image on an image carrier.

[0058]

As described above, according to the present invention, the following effects can be obtained for each claim. In the invention according to claim 1, the image carrier directly self-heats due to electromagnetic induction, so that the electric-heat conversion efficiency is significantly improved, and at the same time, the one having heat capacity such as an electrode or a heating resistor is heat-treated. Since it does not escape, the warm-up time can be shortened. Therefore, the generated heat is dissipated and the energy is not wasted, and energy can be saved.

Further, since it is not necessary to provide the image carrier with a layer made of a heating resistor as in the prior art, the cost is low and the reliability is high.

Further, since the image bearing member can be heated by the induction coil in a non-contact manner, no wear occurs and the life is long, and uniform heating is always obtained, and the image quality is good.

Moreover, since the metal layer that the image carrier usually has can be used as the member to be heated, it is not necessary to separately provide a metal roller for induction heating.

According to the second aspect of the invention, since the absorbed magnetic flux density is high, heat is easily generated, and better fixing is possible.

According to the third aspect of the present invention, the heat-pressure contact fixing can be realized without directly applying pressure to the heated portion, which is preferable when a flexible belt-shaped image carrier is used.

In the invention described in claim 4, the heating efficiency can be increased, and more excellent fixing can be achieved.

According to the fifth aspect of the present invention, the induction coil width can be easily widened and the nip width can be increased. Therefore, not only the time for heating the recording medium itself but also the time for heating the toner is increased. Since it becomes long, the fixing temperature can be set low, and the thermal influence on other processes can be reduced.

According to the sixth aspect of the present invention, the roller rapidly absorbs the unnecessary heat of the image carrier, so that the thermal influence on other processes can be further reduced and the temperature in the main scanning direction can be reduced. Since it is possible to eliminate unevenness and to make it uniform thermally, it is preferable for use when image quality is improved and particularly high-speed printing is required.

According to the invention described in claim 7, a sufficient cooling effect can be obtained even when heat is accumulated by printing for a long time, and unnecessary heat of the image carrier is absorbed more rapidly. As a result, the thermal effect on other processes can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic sectional view of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a schematic sectional view of an image forming apparatus according to a fifth embodiment of the present invention.

6 is a diagram viewed from the left side of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coil assembly, 2 ... Pressure roller (pressure member), 3 ... Coil, 4 ... Core, 10, 11, 12 ... Electrostatic latent image carrier (image carrier), 20 ... Charging means, 30 ... Latent Image writing means, 31 ... Exposure means, 40 ... Developing means, 50 ... Transfer fixing means, 60 ... Rollers, 62 ... Fins (cooling means), 86 ... Fans (cooling means), S ... Sheet (recording medium).

Claims (7)

[Claims] 1. An image forming apparatus for transferring an unfixed toner image formed on an image carrier to a recording medium from the image carrier and simultaneously fixing the image to obtain a recorded image, wherein a transfer unit of the image carrier is provided. An image forming apparatus characterized in that an induction coil is provided in the vicinity of the image carrier to generate an induction current and generate heat. 2. The image forming apparatus according to claim 1, wherein the image carrier has a magnetic metal layer. 3. A pressurizing member, which is in pressure contact with the image carrier, is disposed downstream of a position where heat is generated by the induction coil of the image carrier.
An image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, wherein a core that collects and passes the magnetic flux generated by the induction coil is provided near the induction coil. 5. The image forming apparatus according to claim 1, wherein the image carrier is a flexible belt. 6. An image forming apparatus for transferring an unfixed toner image formed on an image carrier to a recording medium from the image carrier and simultaneously fixing the same to obtain a recorded image, wherein a transfer unit of the image carrier is provided. An image forming apparatus comprising a roller formed of a heat pipe, which is in contact with the image carrier, on the downstream side of the image forming apparatus. 7. The image forming apparatus according to claim 6, further comprising a cooling unit that cools an end portion of the roller.