JP4567852B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device for fixing a toner image (image) on a member to be fixed in an image forming apparatus such as an electrostatic copying machine or a laser printer.
[0002]
[Prior art]
A fixing device incorporated in a copying apparatus using an electrophotographic process heats and melts a developer, that is, toner formed on a member to be fixed, and fixes the toner to the member to be fixed. As a method for heating toner that can be used in the fixing device, a method using radiant heat from a halogen lamp (filament lamp) is widely used. In addition, what is heated non-contactingly using a flash lamp is put into practical use today.
[0003]
In the method using a halogen lamp as a heat source, a pair of rollers is provided so as to be able to provide a predetermined pressure to the member to be fixed and the toner, and at least one of the rollers is formed as a hollow cylinder in a cylindrical shape in its internal space. A configuration in which a halogen lamp is arranged is widely used. In this configuration, the roller on which the halogen lamp is disposed forms an action portion (nip) at a position in contact with the other roller, and supplies pressure and heat to the fixing member and the toner guided to the nip. . That is, the fixing member, that is, the sheet, is passed through a fixing point that is a pressure contact portion (nip) between a heating roller provided with a lamp and a pressure roller that rotates following the heating roller to fuse the toner on the sheet. It is worn and fixed on the paper.
[0004]
In a fixing device using a halogen lamp, light and heat from the halogen lamp are radiated in the entire circumferential direction of the heating roller to heat the whole. In this case, considering the loss when light is converted into heat and the efficiency when the air in the roller is warmed and the heat is transmitted to the roller, the heat conversion efficiency is 60 to 70%. It is known that the power consumption is low and the warm-up time is long.
[0005]
Therefore, in recent years, a heat-resistant film material having a thin metal layer (conductor) is made into an endless belt shape or a cylindrical shape, and a film material is heated by an induction heating method using a magnetic field generated by a magnetic field generator (Japanese Patent Laid-Open No. Hei 8- 76620) and an example using ceramics as a heating member (Japanese Patent Laid-Open No. 59-33476) have been proposed.
[0006]
[Problems to be solved by the invention]
In the induction heating type fixing device described above, the conductor layer immediately after the start of energization to the coil due to the arrangement of the wires of the induction coil for generating an induction current in the conductor layer of the heat resistant film. There is a problem that the temperature is not uniform. For this reason, heating (energization) must be started before rotating the film and the pressure roller for the portion where the toner is likely to adhere to prevent the film from being damaged.
[0007]
Further, in order to improve the heat generation efficiency in the induction heating method, it is necessary to optimize the impedance by optimizing the arrangement and interval of each wire.
[0008]
By the way, when winding the wire constituting the coil around the coil support, as with a general coil, if the wire is simply wound and the interval between the adjacent wires is closely adhered, the conductor (roller body) that is the object to be heated There is a problem that heat radiation is large at both ends in the longitudinal direction, the temperature at both ends is lowered, and the fixing performance is deteriorated.
[0009]
For this reason, in many cases, a method for optimizing the heat generation distribution by changing the gap between the conductor (the inner surface of the roller body) and the coil has been proposed. However, in practice, it is difficult to manage the gap. In addition, there is a problem in that the efficiency decreases due to the provision of the gap.
[0010]
On the other hand, as a method of reducing the temperature unevenness in the rotation axis direction of the roller body (film), in the method using a halogen lamp, a method of changing the light distribution characteristic in the axial direction has been put into practical use. There is a problem that temperature unevenness in the direction orthogonal to the direction in which the fixing medium is conveyed must be reduced.
[0011]
In addition, in the induction heating method, if heat is trapped in the induction coil and the coil core material, there is a problem that the coil core material deforms or melts in the worst case. It is desired to reliably dissipate heat without increasing.
[0012]
If the temperature unevenness is significant, for example, after repeating the fixing operation for a member to be fixed having a small width and passing the member to be fixed having the maximum width, it is caused by a temperature difference in the width direction of the heat resistant film. Thus, there is a problem that wrinkles are generated in the member to be fixed (maximum width).
[0013]
Further, in order to uniformly control the temperature in the width direction of the heat-resistant film, even if the temperature in the longitudinal direction of the heating element can be controlled, the cost of the heating element is greatly increased, while the fixing member to be conveyed is When the width (size) changes, there is a problem that it cannot follow.
[0014]
An object of the present invention is to provide a fixing device capable of reducing temperature unevenness in a width direction of a heat-resistant film while enabling uniform heating of an object to be fixed in a fixing device of an induction heating method. .
[0015]
[Means for Solving the Problems]
The present invention has been made on the basis of the above-described problems. A roller body or a sheet member having a metal layer made of a conductor is formed into a cylinder. Condition Or placed close to an endless member that is oval or endless. excitation In the fixing device that heats the member to be fixed by causing the current to flow through the coil to heat the endless member, excitation The coil is the endless member Arranged along the circumferential direction of the endless member And said excitation coil Configure wire Is the distance between the innermost turn and the second turn from the inner circumference, and the distance between the second turn from the inner circumference and the third turn from the inner circumference. It is an object of the present invention to provide a fixing device having different intervals.
[0020]
The present invention also provides a photosensitive member capable of holding an electrostatic latent image, a developing device for supplying toner to the electrostatic latent image formed on the photosensitive member and developing the photosensitive member, and the developing device to provide a surface on the photosensitive member. An image forming portion that transfers the toner image formed on the transfer member, and a roller body or sheet member having a metal layer made of a conductor are disposed close to an endless member that is cylindrical, elliptical, or endless belt-shaped. excitation A current is passed through the coil to heat the endless member to heat the member to be fixed, and the exciting coil is disposed in parallel to the longitudinal direction of the endless member and along the circumferential direction of the endless member. The wire constituting the exciting coil has an interval between the innermost turn and the second turn from the inner circumference, the second turn from the inner circumference and the third turn from the inner circumference. And an image forming apparatus characterized by having a fixing unit that is set to an interval different from the interval.
[0021]
Furthermore, the present invention provides a cylindrical roller body or sheet member having a metal layer made of a conductor. Condition Or placed close to an endless member that is oval or endless. excitation In the fixing device that heats the member to be fixed by causing the current to flow through the coil to heat the endless member,
Said excitation The coil is the endless member Arranged along the circumferential direction of the endless member And said excitation coil Configure wire Is the distance between the innermost turn and the second turn from the inner circumference, and the distance between the second turn from the inner circumference and the third turn from the inner circumference. At different intervals R , further, Non-magnetic, said excitation The present invention provides a wire support that defines an interval between the wires of the coil.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a fixing device according to an embodiment of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic diagram for explaining a digital copying apparatus as an example of an image forming apparatus to which an embodiment of the present invention is applied.
[0024]
As shown in FIG. 1, a digital copying apparatus (image forming apparatus) 1 is supplied from an image reading apparatus (scanner) 2 that reads an image to be copied as light and dark and generates an image signal, and from the scanner 2 or the outside. And an image forming section 3 that forms an image corresponding to the image signal to be fixed on a sheet P as a fixing member (transfer material). The scanner 2 is integrally provided with an automatic document feeder (ADF) 4 that sequentially replaces the copy target in conjunction with an image reading operation by the scanner 2 when the copy target is a sheet. .
[0025]
The image forming unit 3 includes an exposure device 5 that emits a laser beam corresponding to image information supplied from the scanner 2 or an external device, a photoconductor drum 6 that holds an image corresponding to the laser beam from the exposure device 5, and a photoconductor. A developing device 7 that supplies a developer (toner) to an image formed on the drum 6 and develops it, and a toner image on the photosensitive drum 6 developed by the developing device 7 is fed by a paper feeding / conveying section described below. The image forming apparatus includes a fixing device 8 that heats and melts the developer image transferred to the transfer material P and fixes the image on the transfer material P.
[0026]
In such an image forming apparatus, when an image signal is supplied from the scanner 2 or an external device, the photosensitive drum 6 charged in advance to a predetermined potential is applied to the intensity corresponding to the image signal from the exposure device 5. A modulated laser beam is irradiated. As a result, an electrostatic latent image corresponding to the image to be copied is formed on the photosensitive drum 6.
[0027]
The electrostatic latent image formed on the photosensitive drum 6 is developed by selectively providing toner by the developing device 7 and converted into a toner image (not shown).
[0028]
The toner images on the photosensitive drum 6 are taken out one by one by the pickup roller 10 from the paper cassette 9 holding the paper P at the transfer position facing the transfer device (not labeled), and the photosensitive drum. The aligning roller 12 is used to align the position of the toner image formed on the photosensitive drum 6 with the alignment roller 12 that is conveyed along the conveying path 11 toward the drum 6 and aligns the timing with the toner image on the photosensitive drum 6 (transfer). Transferred to the supplied paper P).
[0029]
The toner transferred onto the paper P is transported to the fixing device 8 where the toner is melted and simultaneously applied with pressure, thereby being fixed onto the paper P.
[0030]
On the other hand, the paper P on which the toner image has been fixed by the fixing device 8 is discharged by a paper discharge roller 13 into a discharge space (discharge tray) 14 defined between the scanner 2 and the paper cassette 9.
[0031]
2 and 3 are schematic diagrams for explaining an example of a fixing device incorporated in the image forming apparatus shown in FIG. 2 is a cross-sectional view of the fixing device, and FIG. 3 is a schematic diagram illustrating a state in which a sheet as a fixing material is passed.
[0032]
As shown in FIG. 2, the fixing device 8 is disposed along the first roller body (endless member) 20 containing the induction heating body 21 and the axis of the first roller body 20. The second roller body 30 is in contact with the surface of the first roller body with a predetermined nip width. Note that either the first roller body or the second roller body is provided with a gear (not shown) that applies a predetermined rotation to both roller bodies and a drive mechanism (not shown) that transmits the rotation to the gear. In addition, the outer diameter of each roller body is 40 mm as an example.
[0033]
The first roller body 20 is, for example, an endless member having a metal layer made of an iron cylinder having a thickness of 1 mm, that is, a conductor, and a release layer such as Teflon is formed on the surface. In addition, stainless steel, aluminum, an alloy of stainless steel and aluminum, or the like can be used for the first roller body 20. Further, as the first roller body, a sheet member in which a thin layer of a metal (such as the above-described iron) having a predetermined thickness is formed on the surface of a heat-resistant film having a predetermined thickness is cylindrical or elliptical, or two An arbitrary shape such as an endless belt shape can be used by the above roller.
[0034]
In the second roller body 30, an elastic material made of silicon rubber or fluorine rubber is shaped around a core metal 31 to a predetermined thickness.
[0035]
The two roller bodies 20 and 30 are in contact with the first roller body 20 with a predetermined pressure by a pressure mechanism (not shown) so that both rollers are in contact with each other. A nip (region where the outer peripheral surface of the second roller body 30 is elastically deformed by pressure contact) N having a predetermined width is provided. When the paper P is conveyed to the nip N, the toner on the paper P is melted by heat and at the same time is fixed (fixed) to the paper P by pressure.
[0036]
On the circumference of the first roller body 20 and downstream of the nip N in the rotational direction, a peeling claw 81 for peeling the paper P from the surface of the second roller body 30, and the first roller body 20 Cleaning member 8 for removing toner transferred from the outer peripheral surface and paper dust from the paper 2 In order to prevent toner from adhering to the outer peripheral surface of the first roller body 20, the temperature of the outer peripheral surface of the release agent coating device 85 and the first aperture body 20 for applying the release agent is measured. put out A temperature sensor 91 comprising a thermistor is provided.
[0037]
As shown in FIG. 3B, two coils 22 are arranged along the circumferential direction of the roller body 20.
[0038]
FIG. 4 is a schematic diagram illustrating the configuration of the induction heating body set on the first roller body of the fixing device described with reference to FIGS. 2 and 3.
[0039]
As shown in FIG. 4, the induction heating body 21 has a cylindrical outer shape formed of, for example, a high heat resistant engineering plastic, and a coil in which a plurality of grooves and curved surfaces (not shown) for winding the wire of the exciting coil 22 are formed. A support body 23 and an exciting coil 22 made of a wire rod wound around the coil support body 23 a predetermined number of times.
[0040]
The exciting coil 22 uses, for example, a litz wire obtained by bundling a plurality (19) of copper wires coated with a heat-resistant polyimide having a diameter of 0.5 mm and insulated from each other, and the longitudinal direction of the first roller body 20 In order to maintain the shape of this wire rod, two plastic coils are arranged along the circumferential direction of the first roller body 20 and parallel to the circumferential direction of the first roller body 20 (see FIG. 3). It is fixed with heat-resistant varnish. In this embodiment, the surface coating and fixing are performed by dipping with a paint containing a heat-resistant silicone resin. Thereby, the further heat-resistant coating of the engineering plastic surface, the heat resistance improvement of a wire, insulation, and adhesion | attachment can be performed. All commercially available heat resistant paints can be expected to have this effect. In addition, by forming the exciting coil 22 with a litz wire, the wire diameter can be made smaller than the penetration depth at which the skin effect occurs, and an alternating current can be passed effectively.
[0041]
The exciting coil 22 is an air-core coil that does not use a core material (for example, a magnetic material such as ferrite or iron core), and the coil support member 23 supports the wire material constituting the coil 22 at a predetermined interval and arrangement. To be used. In the example shown in FIG. 4, the wire rod of the coil 22 has an interval between the innermost turn and the next turn (second from the inner circumference) A, and the second from the inner circumference. When the interval between the turn and the third turn from the inner circumference is B,
B> A
Is satisfied, and the wire is wound so that the interval between the wires of each turn does not change in the longitudinal direction of the first roller body.
[0042]
According to this configuration, the density of magnetic flux generated near the center of the coil where the number of turns becomes “coarse” by increasing the planar coil in the circumferential direction of the first roller body 20 is increased. The uneven heat generation in the circumferential direction of the first roller body 20 can be reduced. Further, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform.
[0043]
In addition, since there is no change in the method (process) for forming the coil 22 and the outer shape of the coil 22, the gap between the first roller body 20 that is the object to be heated and the coil 22 does not change. The temperature at both ends in the longitudinal direction of the roller body 20 can be raised, and in the experiment, the temperature at both ends can be controlled to a temperature about 10 ° C. higher on the conductor of the roller body 20. Thereby, the electric current value which must be supplied to the coil 22 is reduced, and power consumption is suppressed.
[0044]
FIG. 5 is a schematic diagram illustrating another configuration of the induction heating body described with reference to FIG. The same components as those shown in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0045]
As shown in FIG. 5, the induction heating body 21 has a cylindrical outer shape formed of, for example, a high heat resistant engineering plastic, and a coil in which a plurality of grooves and curved surfaces (not shown) for winding the wire of the exciting coil 22 are formed. A support body 23 and an exciting coil 22 made of a wire rod wound around the coil support body 23 a predetermined number of times.
[0046]
In the example shown in FIG. 5, the wire of the induction coil 22 is a region A and a region C (FIG. 5) that are both ends of the first roller body 20 that is divided into four equal parts. 1 4) and a region B (see FIG. 4) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0047]
Specifically, in areas A and C, the interval between the innermost turn and the next turn (second from the inner circumference) is A1, and the second turn from the inner to the inner turn When the interval from the third turn to B3 is B1,
B1> A1
Is wound to satisfy.
[0048]
In region B, the distance between the innermost turn and the next turn (second from the inner circumference) is A2, the second turn from the inner circumference and the third turn from the inner circumference. When the interval between the turns is B2, and the interval between the third turn from the inner periphery and the fourth turn from the inner periphery is C2,
C2> A2, B2 = 0, A1> A2,
Is wound to satisfy.
[0049]
According to this configuration, the density of magnetic flux generated near the center of the coil where the number of turns becomes “coarse” by increasing the planar coil in the circumferential direction of the first roller body 20 is increased. The uneven heat generation in the circumferential direction of the first roller body 20 can be reduced. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform.
[0050]
In other words, the interval between the wires constituting the coil 22 can be arbitrarily changed in a direction perpendicular to the direction in which the paper (fixed member) is conveyed, and the interval in the circumferential direction of the roller body 20 is also an optimal heat distribution. Therefore, the current value that must be supplied to the coil 22 is reduced, and the power consumption is suppressed.
[0051]
FIG. 8 is a schematic diagram illustrating still another configuration of the induction heating body described with reference to FIGS. 4 and 5. As shown in FIG. 4 and FIG. Constitution The same components as those in FIG.
[0052]
As shown in FIG. 8, the induction heating body 21 is partially formed with an excitation coil 22 wound in two layers and a plurality of grooves and curved surfaces (not shown) for winding the wire of the excitation coil 22. A coil support 23.
[0053]
In the example shown in FIG. 8, the wire material of the induction coil 22 is a region A and a region C, which are both ends of the first roller body 20, which are divided into approximately four equal parts (see FIG. 8). 1 4) and a region B (see FIG. 5) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0054]
Specifically, in the region B, the wire rod is placed between the next turn (second from the inner circumference) and the next turn (third from the inner circumference) after the innermost turn of the outer winding. A gap with a distance equal to one diameter as an upper limit is provided. The fifth and sixth wires counted from the inner periphery are wound so as to cover the inner winding wire.
[0055]
On the other hand, in the areas A and C, the interval between the turn next to the innermost turn (second from the inner circumference) and the next turn (third from the inner circumference) disappears, In the region between the two outermost turns of the two planar coils, two turns of the inner winding wire are arranged so as to interrupt the outer winding wire.
[0056]
That is, in the two regions near the center of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, the outer winding is partially spaced in the circumferential direction of the roller body. In contrast, the wire rod is wound around, and at both ends of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, the circumferential direction of the roller body is such that each turn is filled with the wire rod. It is wound.
[0057]
According to this configuration, the number of wires arranged in the circumferential direction at the end in the longitudinal direction of the roller body (number of turns) is equal to the number of wires arranged in the longitudinal direction of the roller body (number of turns). Therefore, it is possible to compensate for the temperature that decreases by the amount of heat that escapes from the end of the roller body in the longitudinal direction. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, the heat generation efficiency is improved.
[0058]
FIG. 9 is a schematic diagram illustrating still another configuration of the induction heating body described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure same as shown in FIG. 8, and detailed description is abbreviate | omitted.
[0059]
As shown in FIG. 9, the induction heating body 21 is partially formed with an excitation coil 22 wound in two layers and a plurality of grooves and curved surfaces (not shown) for winding the wire of the excitation coil 22. A coil support 23.
[0060]
In the example shown in FIG. 9, the wire material of the induction coil 22 is a region A and a region C, which are both ends of the first roller body 20, which are divided into four equal parts (see FIG. 9). 1 4) and a region B (see FIG. 5) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0061]
Specifically, in the region B, the fourth turn from the inner circumference of the outer winding is between the fourth turn from the inner circumference of the outer winding and the next turn (the fifth from the inner circumference), and the fourth from the inner circumference of the outer winding. A gap with a distance equal to the diameter of one wire as an upper limit is provided between the next turn and the next turn (sixth from the inner periphery). The fifth and sixth wires counted from the inner periphery are wound so as to cover the inner winding wire.
[0062]
On the other hand, in the areas A and C, the diameter of one wire between the turn next to the innermost turn (second from the inner circumference) and the next turn (third from the inner circumference) A gap having an upper limit of a distance equal to is provided.
[0063]
That is, in the two regions near the center of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, the outer winding is partially spaced in the circumferential direction of the roller body. In contrast, the wire rod is wound, whereas at both ends of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, several turns of the wire rod cover the inner winding. It is moved in the circumferential direction of the roller body.
[0064]
According to this configuration, the number of wires arranged in the circumferential direction at the end in the longitudinal direction of the roller body (number of turns) is equal to the number of wires arranged in the longitudinal direction of the roller body (number of turns). Therefore, it is possible to compensate for the temperature that decreases by the amount of heat that escapes from the end of the roller body in the longitudinal direction. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, the heat generation efficiency is improved.
[0065]
FIG. 10 is a schematic diagram illustrating another configuration of the induction heating body described with reference to FIGS. 4 and 5. As shown in FIG. 4 and FIG. Constitution The same components as those in FIG.
[0066]
As shown in FIG. 10, the induction heating body 21 is wound around the coil support 23 a predetermined number of times, and a coil support 23 in which a plurality of grooves and curved surfaces (not shown) for winding the wire of the excitation coil 22 are formed. It consists of an exciting coil 22 made of wire.
[0067]
In the example shown in FIG. 10, the wire of the induction coil 22 has a region A and a region C (FIG. 1 4) and a region B (see FIG. 4) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0068]
Specifically, in areas A and C, the interval between the innermost turn and the next turn (second from the inner circumference) is A1, and the second turn from the inner to the inner turn When the interval from the third turn to B3 is B1,
B1> A1
Is wound to satisfy.
[0069]
In the region B, the diameter of one wire constituting the coil 22 is slightly larger between the third turn from the innermost side and the next turn (fourth from the inner circumference). A spacing C is given. In the region B, the interval Z ′ between the innermost turns of the planar coil is narrower than the interval Z between the turns in the regions A and C (correspondingly, the interval C is the above-described figure). 4 to wider than any of the embodiments shown in FIG.
[0070]
According to this configuration, the density of magnetic flux generated near the center of the coil where the number of turns becomes “coarse” by increasing the planar coil in the circumferential direction of the first roller body 20 is increased. The uneven heat generation in the circumferential direction of the first roller body 20 can be reduced. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, since the interval between the wire members in the circumferential direction of the roller body 20 is optimized, the utilization efficiency of the induced current from each wire member is improved.
[0071]
FIG. 11 is a schematic diagram illustrating an example in which the induction heating elements described with reference to FIGS. 9 and 10 are combined. In addition, it showed in FIG. 9 and FIG. Constitution The same components as those in FIG.
[0072]
As shown in FIG. 11, the induction heating body 21 is partially formed with an excitation coil 22 wound in two layers and a plurality of grooves and curved surfaces (not shown) for winding the wire of the excitation coil 22. A coil support 23.
[0073]
In the example shown in FIG. 11, the wire of the induction coil 22 is a region A and a region C, which are both ends of the first roller body 20 in the longitudinal direction divided into approximately four (see FIG. 11). 1 4) and a region B (see FIG. 5) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0074]
Specifically, in the region B, the diameter of one wire constituting the coil 22 is between the third turn from the inner periphery of the outer winding and the next turn (fourth from the inner periphery). A slightly larger distance C is also given. In the region B, the distance Z ′ between the innermost turns of the planar coil is narrower than the distance Z between the turns in the regions A and C.
[0075]
In the areas A and C, the interval between the innermost turn and the next turn (second from the inner circumference) is A1, and the second turn from the inner circumference and 3 from the inner circumference. When the interval between the first turn is B1,
B1> A1
Is wound to satisfy.
[0076]
According to this configuration, the density of magnetic flux generated near the center of the coil where the number of turns becomes “coarse” by increasing the planar coil in the circumferential direction of the first roller body 20 is increased. The uneven heat generation in the circumferential direction of the first roller body 20 can be reduced. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, since the interval between the wire members in the circumferential direction of the roller body 20 is optimized, the utilization efficiency of the induced current from each wire member is improved.
[0077]
FIG. 12 is a schematic diagram illustrating still another configuration of the induction heating body described with reference to FIGS. 4, 5, and 8. As shown in FIG. 4 and FIG. Constitution The same components as those in FIG.
[0078]
As shown in FIG. 12, the induction heating body 21 is partially formed with an excitation coil 22 wound in two layers and a plurality of grooves and curved surfaces (not shown) for winding the wire of the excitation coil 22. A coil support 23.
[0079]
In the example shown in FIG. 12, the wire of the induction coil 22 is a region A and a region C that are both ends of the first roller body 20 in the longitudinal direction divided into approximately four parts (see FIG. 12). 1 4) and a region B (see FIG. 5) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0080]
Specifically, in the region B, the wire rod is placed between the next turn (second from the inner circumference) and the next turn (third from the inner circumference) after the innermost turn of the outer winding. A gap with a distance equal to one diameter as an upper limit is provided. The fifth and sixth wires counted from the inner periphery are wound so as to cover the inner winding wire.
[0081]
On the other hand, in the areas A and C, the interval between the turn next to the innermost turn (second from the inner circumference) and the next turn (third from the inner circumference) disappears, In the area between the two outermost turns of the two planar coils, two turns closer to the center of the inner winding wire are inserted into the outer winding wire and the same as the outer wire. They are arranged so that they are in phase.
[0082]
That is, in the two regions near the center of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, the outer winding is partially spaced in the circumferential direction of the roller body. Whereas the wire rod is wound, the circumferential direction of the roller body is filled with the wire rod at both ends of the first roller body 20 divided into approximately four equal parts with respect to the longitudinal direction of the first roller body 20, and Each turn is wound so that it is in phase with the wire.
[0083]
According to this configuration, the number of wires arranged in the circumferential direction at the end in the longitudinal direction of the roller body (number of turns) is equal to the number of wires arranged in the longitudinal direction of the roller body (number of turns). Therefore, it is possible to compensate for the temperature that decreases by the amount of heat escaping from the end of the roller body in the longitudinal direction. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, the heat generation efficiency is improved.
[0084]
FIG. 13 is a schematic diagram illustrating still another configuration of the induction heating body described with reference to FIG. As shown in FIG. Constitution The same components as those in FIG.
[0085]
FIG. 3 As shown in FIG. 1, the induction heating body 21 includes an exciting coil 22 that is partially wound in two layers, and a coil support body on which a plurality of grooves and curved surfaces (not shown) for winding the wire of the exciting coil 22 are formed. 23.
[0086]
FIG. 3 In the example shown in FIG. 2, the wire material of the induction coil 22 is a region A and a region C which are both ends of the first roller body 20 in the longitudinal direction divided into approximately four parts (see FIG. 1 4) and a region B (see FIG. 5) sandwiched between regions A and C. 1 4), the interval between the wire rods is changed in the circumferential direction of the first roller body 20.
[0087]
Specifically, in the region B, the fourth turn from the inner circumference of the outer winding is between the fourth turn from the inner circumference of the outer winding and the next turn (the fifth from the inner circumference), and the fourth from the inner circumference of the outer winding. A gap with a distance equal to the diameter of one wire as an upper limit is provided between the next turn and the next turn (sixth from the inner periphery). The fifth and sixth wires counted from the inner periphery are wound so as to cover the inner winding wire.
[0088]
On the other hand, in the areas A and C, the diameter of one wire between the turn next to the innermost turn (second from the inner circumference) and the next turn (third from the inner circumference) A gap having an upper limit of a distance equal to is provided.
[0089]
That is, in the two regions near the center of the first roller body 20 divided into approximately four equal parts in the longitudinal direction, the outer winding is partially spaced in the circumferential direction of the roller body. Whereas the wire rod is wound, the outer diameter shape of the outer winding is changed so as to cover the inner winding at both ends of the first roller body 20 divided into approximately four equal parts in the longitudinal direction. In order to prevent this, a number of turns of the outer winding wire are moved in the circumferential direction of the roller body so as not to be spaced apart by more than one wire.
[0090]
According to this configuration, the number of wires arranged in the circumferential direction at the end in the longitudinal direction of the roller body (number of turns) is equal to the number of wires arranged in the longitudinal direction of the roller body (number of turns). Therefore, it is possible to compensate for the temperature that decreases by the amount of heat escaping from the end of the roller body in the longitudinal direction. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform. Further, the heat generation efficiency is improved.
[0091]
FIG. 14 is a schematic diagram illustrating still another configuration of the induction heating body described with reference to FIG. As shown in FIG. Constitution The same components as those in FIG.
[0092]
As shown in FIG. 14, the induction heating body 21 is a cylindrical coil support in which a plurality of grooves and curved surfaces (not shown) are formed. 1 23 and coil support 1 The exciting coil 22 is made of a wire wound around a predetermined number of times.
[0093]
The wire of the induction coil 22 is divided into the area A and the area C, which are both ends of the first roller body 20 divided into four equal parts in the longitudinal direction. And , The region between regions A and C B and In the circumferential direction of the first roller body 20, the interval between the wire members is changed.
[0094]
Specifically, in the excitation coil 22, in the region B, the distance B between the wire rods, which is the innermost turn of each of the two planar coils 22, is the distance A between the corresponding wire rods in the regions A and B. Alternatively, the interval between the wire members is changed in the circumferential direction of the first roller body 20 so as to be narrower than C.
[0095]
According to this configuration, the density of magnetic flux generated near the center of the coil where the number of turns becomes “coarse” by increasing the planar coil in the circumferential direction of the first roller body 20 is increased. The uneven heat generation in the circumferential direction of the first roller body 20 can be reduced. Therefore, the temperature distribution on the outer peripheral surface of the first roller body 20 can be made uniform.
[0096]
FIG. 6 shows the coil support used for each induction heating body described above with reference to FIGS. 4, 5 and 8 to 13 and the position of the wire in each coil in the circumferential direction of the first roller body. It is the schematic explaining the structure for making it do.
[0097]
FIG. 6 shows a plurality of spacers made of heat-resistant resin at specific positions in the circumferential direction in order to define the arrangement of the wires outside the region B in the induction heating body shown in FIG. (Spacing holders) 601 and 602 are provided.
[0098]
As the spacers (interval holders) 601, 602, liquid crystal polymer, polyester, phenol, PEEK, etc. having a heat resistant temperature of 200 ° C. or higher can be preferably used.
[0099]
Further, the spacers 601 and 602 are formed to have a maximum thickness (the amount of increase in radius) smaller than the diameter of the wire constituting the coil.
[0100]
By using the spacers 601 and 602, the interval between adjacent wires of the exciting coil 22 can be easily set, and a coil that requires winding of a complicated wire with an optimized heat generation distribution can be accurately formed.
[0101]
FIG. 7 is a schematic diagram for explaining the feature of the shape of the coil support used in each induction heating body described above with reference to FIGS. 4, 5 and 8 to 13.
[0102]
FIG. 7 shows an example in which the spacers 601 and 602 described with reference to FIG. 6 are part of the coil support 23 and the guides 23 a and 23 b are integrally formed on the coil support 23.
[0103]
The guide 23a. The thickness of 23b (increase in radius) is at most smaller than the diameter of the wire constituting the coil. FIG. 8 shows a state in which spacers (interval holders) 601 and 602 having the number of wires arranged outside the region B are provided in the induction heating body shown in FIG.
[0104]
According to this configuration, it is possible to easily set the interval between adjacent wires of the exciting coil 22 and accurately form a coil that requires winding of a complicated wire with an optimized heat generation distribution.
[0105]
15 to 17 are schematic diagrams for explaining the configuration of the coil support of the induction heating body shown in FIGS. 4 to 14.
[0106]
As shown in FIG. 15, the coil support 223 has a first rib 223a for defining a distance between the innermost circumferences of two planar coils, and an innermost circumference defined along the first rib 223a. Inverted curved surface portion 223b in which the direction of the wire rod of the coil 22 is changed by 180 °, and a multi-layer on which the wire rods of the inner turns for winding the outer and inner two layers as shown in FIG. A coil guide part 223d around which the wire material of each turn, which is a major part of the coil 22, is wound around the guide part 223c and the wire material of the coil 22 whose innermost circumference is defined along the first rib 223a; The multilayer guide portion 223c and the coil guide portion 223d are provided so as to extend from the thicker portion of the coil guide portion 223d toward the center. And a pair of heat radiation openings 223e and 223f for suppressing the temperature of the support 223 from excessively rising when energized by being assembled as an induction heating body. .
[0107]
Note that, as shown in FIG. 16, the heat radiation openings 223e and 223f are formed so as to be shifted from each other when viewed from the side. Further, the shape of the holes of the heat radiation openings 223e and 223f is shown as a perfect circle in the figure, but may be an ellipse that is long in the axial direction of the support 223, or may be a rectangle. Good.
[0108]
Accordingly, as is apparent from FIG. 17, the internal air can also move in the axial direction of the coil support perpendicular to the axial direction of the heat radiation openings 223e and 223f.
[0109]
By providing a plurality of such heat radiation openings 223e and 223f in a direction orthogonal to the axial direction of the coil support 223, air can flow also in the axial direction of the coil support 223.
[0110]
As a result, heat is generated from the first roller body as a result of energization of the coil 22, radiation from the conductor (wire) constituting the coil itself, and current flowing through the wire constituting the coil. Cooling against much heat generated by Joule loss or the like becomes possible.
[0111]
Although not shown, by combining with a cooling fan, it is possible to obtain a cooling capability that can be reliably prevented at a predetermined temperature at which the coil support 223 is not thermally deformed due to a temperature rise.
[0112]
【The invention's effect】
As described above, the fixing device according to the present invention induces temperature unevenness that may occur when a heat-resistant film having a small heat capacity is used in an endless form for heating, and is set on the side of the endless form to be heated. Since the coil wire constituting the heating element is arranged and wound so that the spacing and arrangement between the wires change in the longitudinal direction of the endless object to be heated, the endless object to be heated is wound. Can be heated uniformly.
[0113]
In addition, the arrangement of the wires that can uniformly heat the object to be heated enables the temperature of the object to be heated to be increased despite the reduction in power consumption.
[0114]
With such a configuration, it is possible to obtain a fixing device with a short warm-up time, uniform fixing properties throughout the entire area, and low power consumption.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus to which a fixing device according to an embodiment of the present invention is applied.
FIG. 2 is a schematic cross-sectional view illustrating an example of a fixing device incorporated in the image forming apparatus illustrated in FIG.
FIG. 3 is a schematic diagram for explaining the shape of the fixing device shown in FIG. 2;
4 is a schematic diagram illustrating an example of an induction heating body incorporated in the fixing device illustrated in FIGS. 2 and 3. FIG.
FIG. 5 is a schematic cross-sectional view illustrating another embodiment of the induction heating body shown in FIG.
6 is a schematic cross-sectional view illustrating a configuration of a support that supports a wire of a coil of the induction heating body illustrated in FIGS. 4 and 5. FIG.
7 is a schematic cross-sectional view illustrating the configuration of a support that supports the wire of the coil of the induction heating body shown in FIGS. 4 and 5. FIG.
FIG. 8 is a schematic diagram illustrating still another embodiment of the induction heating body shown in FIG.
FIG. 9 is a schematic diagram illustrating still another embodiment of the induction heating body shown in FIG.
10 is a schematic diagram for explaining still another embodiment of the induction heating body shown in FIG.
FIG. 11 is a schematic diagram illustrating still another embodiment of the induction heating body shown in FIG.
12 is a schematic view illustrating still another embodiment of the induction heating body shown in FIG.
FIG. 13 is a schematic diagram illustrating still another embodiment of the induction heating body shown in FIG. 4;
FIG. 14 is a schematic diagram illustrating still another embodiment of the induction heating body shown in FIG.
15 is a schematic diagram for explaining the characteristics of the coil support of the induction heating body shown in FIGS. 4 to 14. FIG.
16 is a schematic diagram for explaining the characteristics of the coil support of the induction heating body shown in FIGS. 4 to 14 and showing a state seen from a side surface direction different from the direction shown in FIG. 15;
FIG. 17 is a schematic diagram illustrating a state in which a part of the coil support body of the induction heating body illustrated in FIGS.
[Explanation of symbols]
1 ... Image forming apparatus,
3 ... Image forming section
8 ・ ・ ・ Fixing device,
9 ・ ・ ・ Paper cassette,
20 ... 1st roller body (heating),
21 ... induction heating body,
22 ... induction coil,
23 ... Coil support,
30 ... second roller body (pressurization),
81 ... peeling nails,
83 ... Cleaning member,
85 ... Release agent coating device,
91 ・ ・ ・ Temperature sensor,
601... Spacer,
602: Spacer.

Claims (6)

The member to be fixed is heated by causing a current to flow through an exciting coil in which a roller body or a sheet member having a metal layer made of a conductor is arranged in the vicinity of an endless member having a cylindrical shape, an elliptical shape or an endless belt shape to heat the endless member. In the fixing device,
The exciting coil is arranged in parallel with the longitudinal direction of the endless member and along the circumferential direction of the endless member, and the wire constituting the exciting coil has the innermost turn and inner circumferential surface. The fixing device is characterized in that the interval from the second turn to the second turn is set to be different from the interval from the second turn from the inner periphery to the third turn from the inner periphery.   The interval between the innermost turn of the wire of the exciting coil and the second turn from the inner periphery is smaller than the interval between the second turn from the inner periphery and the third turn from the inner periphery. The fixing device according to claim 1.   The fixing device according to claim 1, further comprising a support body that defines an interval between turns of the wire of the exciting coil. A photosensitive member capable of holding an electrostatic latent image, a developing device that supplies toner to the electrostatic latent image formed on the photosensitive member for development, and the toner formed on the photosensitive member by the developing device An image forming unit for transferring an image to a transfer target;
The member to be fixed is heated by causing a current to flow through an excitation coil in which a roller body or a sheet member having a metal layer made of a conductor is disposed in the vicinity of an endless member having a cylindrical shape, an elliptical shape or an endless belt shape to heat the endless member. The exciting coil is arranged in parallel to the longitudinal direction of the endless member and along the circumferential direction of the endless member, and the wire constituting the exciting coil is the innermost circumferential surface. An interval between the second turn from the inner circumference and the second turn from the inner circumference is set to be different from an interval between the second turn from the inner circumference and the third turn from the inner circumference;
An image forming apparatus comprising: The member to be fixed is heated by causing a current to flow through an exciting coil in which a roller body or a sheet member having a metal layer made of a conductor is arranged in the vicinity of an endless member having a cylindrical shape, an elliptical shape or an endless belt shape to heat the endless member. In the fixing device,
The exciting coil is arranged in parallel with the longitudinal direction of the endless member and along the circumferential direction of the endless member, and the wire constituting the exciting coil has the innermost turn and inner circumferential surface. The distance from the second turn to the second turn is different from the distance from the second turn from the inner circumference to the third turn from the inner circumference,
The fixing device further includes a wire support that is non-magnetic and defines a distance between the wires of the exciting coil. The distance between the innermost turn of the wire of the exciting coil and the second turn from the inner circumference is smaller than the distance between the second turn from the inner circumference and the third turn from the inner circumference. The fixing device according to claim 5 .

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