JP6783560B2 - Heating rotating body and image heating device - Google Patents

Description

The present invention relates to a heating rotating body and an image heating device.

The heating rotating body and the image heating device can be used in an image forming device such as an electrophotographic copying machine or a printer. Examples of the image heating device include a fixing device for fixing an unfixed toner image formed on a recording material and a gloss imparting device for improving the glossiness of an image by heating the toner image fixed on the recording material. To be done.

The fixing device mounted on the image forming device heats the recording material carrying the unfixed toner image in the nip portion formed by the heating rotating body and the pressing roller as the pressing member in contact with the heating rotating body while conveying the recording material. In general, the toner image is fixed on the recording material.

In recent years, an electromagnetic induction heating type fixing device capable of directly generating heat of a conductive layer (resistive heating element) of a heating rotating body has been developed and put into practical use. Such a fixing device has an advantage that the warm-up time is short.

The electromagnetic induction heating type fixing device disclosed in Patent Document 1 includes a core and a coil wound in a spiral shape inside a tubular rotating body having a conductive layer, and the spiral shaft thereof is a rotating body. It is substantially parallel to the generatrix direction of the above, and generates heat by inducing a circumferential current in the conductive layer. This fixing device has few restrictions on the thickness of the conductive layer and the material of the conductive layer, and can generate heat in the conductive layer with high efficiency. This heating rotating body usually has a layer structure in which an elastic layer and a release layer are coated on the outer peripheral surface of a tubular conductive layer.

Japanese Unexamined Patent Publication No. 2014-0226267

However, since the elastic layer and the release layer are not sufficiently strong, they may be scratched by foreign matter entering from outside the machine or rubbing against the recording material, and the scratches may extend to the conductive layer. Furthermore, there is a possibility that the conductive layer may be damaged when the user himself / herself uses a cutter during jam processing. In such a case, the current density may increase locally around the edge of the wound, and that portion may locally overheat.

FIG. 16 shows that in a fixing device using a heating rotating body (fixing sleeve, fixing film: hereinafter referred to as a fixing sleeve) having such a configuration, cracks 1k due to scratches were generated in the tubular conductive layer 1a of the fixing sleeve. It is a schematic diagram which showed the state of the current concentration in the state. That is, it is a schematic diagram showing how the orbital current I flowing in the conductive layer 1a is concentrated near the end portion (damaged end) C of the crack 1k.

In the region "Z1" where the tubular conductive layer 1a is not damaged in the circumferential direction, the induced electromotive force generated in the conductive layer 1a causes a current (circumferential current) I to flow in the circumferential direction as shown by an arrow. In the damaged region "Z2", the current I flowing in the circumferential direction bypasses, and the current flows around the damaged end C. Therefore, the temperature near the end of the crack 1k of the conductive layer 1a is locally overheated as compared with other regions. Such localized excessive temperature rise of the portion is the temperature than normal portion becomes considerably high, in some cases may grant a thermal damage to the fixing sleeve.

Therefore, an object of the present invention is to provide a heating rotating body and an image heating device capable of preventing local overheating due to cracks in a tubular heating rotating body provided with a conductive layer. To do.

In order to achieve the above object, a typical configuration of the heating rotating body according to the present invention is a tubular heating rotating body having a conductive layer, which is arranged inside the heating rotating body, and a spiral shaft of the heating rotating body. A coil having a spiral-shaped portion extending in a direction along the bus direction and forming an alternating magnetic field for electromagnetically inducing heat generation of the conductive layer, and a magnetic field line of the alternating magnetic field arranged in the spiral-shaped portion. The heating rotating body provided with a magnetic core for guiding and used in an image heating device for heating a recording material on which an image is formed, and the conductive layer has a direction in which a spiral axis is along the bus direction. said first conductive path first conductive path to each other are formed in a spiral shape so as not to contact adjacent to each other in and the generatrix direction so as to intersect with the first conductive path, said first possess a second conductive path and is electrically connected with said first conductive path at a point intersecting with the conductive paths, and the alternating by the second conductive path between said first conductive path It is characterized in that a closed circuit through which an induced current due to a magnetic field flows is formed .

Further, in order to achieve the above object, a typical configuration of the image heating device according to the present invention is a tubular heating rotating body having a conductive layer and being arranged inside the heating rotating body, and the spiral shaft is the heating rotation. A coil having a spiral-shaped portion extending in a direction along the bus direction of the body and forming an alternating magnetic field for electromagnetically inducing heat generation of the conductive layer, and a coil arranged in the spiral-shaped portion of the alternating magnetic field. In an image heating device provided with a magnetic core for inducing magnetic field lines and heating a recording material on which an image is formed, the conductive layer has a spiral axis in a direction along the bus line direction and the bus line. intersecting said first conductive path first conductive path adjacent is formed in a spiral shape so as not to contact in the direction, and the first conductive path intersects with the first conductive path have a, a second conductive path is conducting the first conductive path electrically in place, close the flows induced current by the alternating magnetic field by said second conductive path and said first conductive path It is characterized in that a circuit is formed .

According to the present invention, it is possible to provide a heating rotating body and an image heating device capable of preventing local overheating due to cracks in a tubular heating rotating body provided with a conductive layer.

The conceptual diagram explaining the relationship between the 1st conductive path and the 2nd conductive path in the fixing sleeve of Example 1. Schematic configuration diagram of the image forming apparatus according to the first embodiment (A) is a cross-sectional side view of a main part of the fixing device according to the first embodiment, and (B) is a schematic view showing a layer structure of a fixing sleeve. Front model view of the main part of the fixing device Perspective view of coil and core part and block diagram of control system Conceptual diagram of coil shape and core shape Conceptual diagram illustrating the outline of the shape of the first conductive path Explanatory drawing of the method of forming a conductive path in the configuration of Example 1. Schematic diagram for explaining the effect of the fixing sleeve of Example 1. The figure explaining the case where the angle of θ2 is reduced in the relationship between θ1 and θ2. The figure explaining the case where θ1 = θ2 and the junction part of the conductive path 1 and 2 does not exist. The figure explaining the structure in the case of forming by connecting the conductive paths around. The figure explaining the structure which wound the conductor braided wire around the surface of the fixing sleeve base layer. The figure explaining the structure which closes the gap of the conductor braided wire and uses the conductor braided wire itself as a fixing sleeve base layer. The figure explaining the weaving of the warp yarn wound in a spiral direction and the weft yarn formed in a longitudinal direction. Schematic diagram showing how the current flowing in the conductive layer of the fixing sleeve of the comparative example is concentrated near the crack end.

[Example 1]
(1) Image forming unit FIG. 2 is a schematic configuration diagram of an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 is a laser beam printer using an electrophotographic process. Reference numeral 101 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a drum) as an image carrier, which is rotationally driven at a predetermined peripheral speed in the clockwise direction indicated by the arrow. In the process of rotation, the drum 101 is uniformly charged to a predetermined polarity and potential by the charging roller 102.

Reference numeral 103 denotes a laser beam scanner as an exposure means. As shown in FIG. 5, the scanner 103 outputs laser light L modulated according to image information input to the printer controller 41 of the control circuit unit (control unit) 40 from an external device 42 such as an image scanner or a computer. , The charged surface of the drum 101 is scanned and exposed. By this exposure, the electric charge on the drum surface is eliminated, and an electrostatic latent image corresponding to the image information is formed on the drum surface. Reference numeral 104 denotes a developing device, in which toner is supplied from the developing roller 104a to the drum surface to develop an electrostatic latent image as a toner image.

Reference numeral 105 denotes a feeding cassette in which the recording material P is loaded and accommodated. The feeding roller 106 is driven based on the feeding start signal, and the recording materials P in the feeding cassette are separated and fed one by one. The recording material P is introduced into the transfer nip 108T formed by the drum 101 and the transfer roller 108 via the registration roller 107 at a predetermined timing. That is, at the timing when the tip of the toner image on the drum reaches the transfer nip 108T, the registration roller 107 controls the transfer of the recording material P so that the tip of the recording material P reaches the transfer nip 108T.

The recording material P introduced into the transfer nip 108T is conveyed by the transfer nip 108T, and during that time, a transfer bias voltage having a polarity opposite to the charging polarity of the toner is applied to the transfer roller 108 by a power source (not shown). As a result, the toner image on the drum side is transferred to the surface of the recording material P at the transfer nip 108T. After that, the recording material P is separated from the surface of the drum 101 and is fixed by the fixing device A as an image heating device via the transport guide 109. The fixing device A will be described later.

The surface of the drum 101 after the recording material is separated is cleaned by the cleaning device 110, and is repeatedly subjected to image formation. Then, the recording material P that has passed through the fixing device A is discharged onto the discharge tray 112 from the discharge port 111.

(2) Fixing device In this embodiment, the fixing device A is an electromagnetic induction heating type device. FIG. 3A is a cross-sectional side model view of a main part of the fixing device A in this embodiment, and FIG. 3B is a schematic view showing a layer structure of the fixing sleeve 1. FIG. 4 is a front model view of a main part of the fixing device A, and FIG. 5 is a perspective view of a coil and a core part and a block diagram of a control system. Here, with respect to the fixing device A, the front side is the side where the recording material P is introduced. Left and right are left or right when the fixing device A is viewed from the front side. The fixing device A roughly includes a heating assembly 7 as a heating member, a pressure roller 8 as a pressure member, and a device chassis (not shown) in which these are assembled.

The heating assembly 7 includes a fixing sleeve 1 as a tubular heating rotating body having a conductive layer 1a, a coil 3 arranged inside the fixing sleeve 1, and a magnetic core arranged in a spiral-shaped portion of the coil 3. Has 2. The coil 3 has a spiral-shaped portion in which the spiral shaft extends in the direction along the generatrix direction of the fixing sleeve 1, and is a member that forms an alternating magnetic field that causes the conductive layer 1a of the fixing sleeve 1 to generate heat by electromagnetic induction. The core 2 is a member that guides the magnetic field lines of the alternating magnetic field formed by the coil 3.

Further, the heating assembly 7 has a sleeve guide member 6 arranged inside the fixing sleeve 1 and a rigid stay for pressurization (hereinafter, referred to as a stay) 5. The sleeve guide member 6 is supported by the stay 5. The units of the coil 3 and the core 2 are arranged in a space formed between both the sleeve guide member 6 and the stay 5. Both ends of the stay 5 project from both ends of the fixing sleeve 1 as shown in FIG.

The pressure roller 8 is composed of a core metal 8a and a heat-resistant elastic material layer 8b that is concentrically molded and coated around the core metal in a roller shape, and a release layer 8c is provided on the surface layer. .. The elastic layer 8b is preferably made of silicone rubber, fluororubber, fluorosilicone rubber or the like and has good heat resistance. Both ends of the core metal 8a are arranged so as to be rotatably held between the left and right side sheets of the device chassis via conductive bearings.

The heating assembly 7 is arranged above the pressure roller 8 with the sleeve guide member 6 facing the pressure roller 8 and substantially parallel to the pressure roller 8. Then, as shown in FIG. 4, a pressing force is applied to the stay 5 by contracting the pressure springs 17a and 17b between both ends of the stay 5 and the left and right spring receiving members 18a and 18b on the device chassis side, respectively. I'm letting you. In the fixing device A of this embodiment, a pressing force having a total pressure of about 100 N to 250 N is applied.

As a result, the lower surface of the sleeve guide member 6 made of heat-resistant resin PPS or the like and the upper surface of the pressure roller 8 are pressure-welded with the pushing force of the stay 5 sandwiching the flexible fixing sleeve 1 which is a cylindrical rotating body. A fixing nip portion N having a predetermined width is formed in the recording material transport direction a.

The pressure roller 8 is rotated in the counterclockwise direction of arrow in FIG. 3 (A) by driving means (not shown), rotates the fixing sleeve 1 by a frictional force between the outer surface of the fixing sleeve 1 at the fixing nip N Force acts. As a result, the fixing sleeve 1 rotates in the clockwise direction indicated by the arrow while the inner surface thereof slides in close contact with the surface of the sleeve guide member 6 at the fixing nip portion N. The recording material P is introduced into the fixing nip portion N and is sandwiched and conveyed.

(3) Fixing sleeve As shown in FIG. 3B, the fixing sleeve 1 has a conductive layer (hereinafter referred to as a heat generating layer) 1a, an elastic layer 1b laminated on the outer surface thereof, and a release laminated on the outer surface thereof. It is a tubular rotating body having the flexibility of the composite structure of the mold layer 1c.

In the free state, the fixing sleeve 1 has a substantially cylindrical shape due to its own elastic force. In this embodiment, the fixing sleeve 1 has a diameter of 10 to 50 mm, and the total thickness of the heat generating layer 1a, the elastic layer 1b, and the release layer 1c is 1 mm or less, and has appropriate flexibility. The purpose is to efficiently heat the recording material P by widening the nip portion N, and to improve the quick start property by reducing the heat capacity.

In the fixing sleeve 1 of this embodiment, the heat generating layer 1a is a tubular electrically insulating / heat resistant base layer 1a3, a first conductive path 1a1 and a second conductive path which are conductive patterns formed on the outer surface thereof. It has 1a2. In this embodiment, the base layer 1a3 is made of a heat-resistant resin such as polyimide or polyamide having a film thickness of 10 to 50 μm, and the first and second conductive paths 1a1 and 1a2 are patterned with a conductive paint such as silver paste. .. Joule heat is generated by passing an induced current through this conductive path. Details of the conductive paths 1a1 and 1a2 will be described later.

The elastic layer 1b is formed by molding a silicone rubber having a hardness of 20 degrees from 0.3 mm to 0.1 mm. Then, a fluororesin tube having a thickness of 50 μm to 10 μm is coated on the elastic layer 1b as the surface layer 1c. An alternating magnetic flux is applied to the conductive layer 1a to generate an induced current in the conductive paths 1a1 and 1a2 to generate heat. This heat is transferred to the elastic layer 1b and the release layer 1c, the entire fixing sleeve 1 is heated, and the recording material P as a member to be heated introduced into the nip portion N is heated to fix the toner image T (the toner image T is fixed. Image heating) is done.

(4) Explanation of Heating Control FIG. 5 is a diagram showing a fixing sleeve 1 which is a heating rotating body, a magnetic core 2, an exciting coil 3, and a circuit block. Reference numeral 9 denotes a temperature measuring element such as a non-contact thermistor that detects the surface temperature of the fixing sleeve 1. The temperature measuring element 9 is arranged on the upstream side of the recording material transport direction a with respect to the nip N so as to detect the temperature of the sleeve portion at the center of the longitudinal length of the fixing sleeve 1. By inputting the detection temperature information of the temperature measuring element 9 to the fixing temperature control unit 44 of the control circuit unit 40, the temperature of the surface of the fixing sleeve 1 is maintained and adjusted to a predetermined target temperature.

In the control circuit unit 40, the printer controller 41 communicates with the host computer 42, which is an external device, receives image data, and expands the received image data into information that can be printed by the printer. Further, the printer controller 41 exchanges signals and performs serial communication with the engine control unit 43.

The engine control unit 43 exchanges signals with the printer controller 41, and further controls the power control unit 46, the fixing temperature control unit 44, and the frequency control unit 45 of the printer engine via serial communication. The fixing temperature control unit 44 controls the temperature of the fixing device A based on the temperature detected by the temperature measuring element 9. The power control unit 46 as the power adjusting means adjusts the voltage applied to the exciting coil 3 to control the power of the high frequency converter 16. The frequency control unit 45 controls the frequency of the output high frequency of the high frequency converter 16. 3a and 3b are power input terminals for the coil 3.

In a printer system having such a printer control unit 40, the host computer 42 transfers image data and sets various print conditions such as a recording material size in response to a request from a user.

(5) Explanation of Heating Principle The magnetic core 2 is inserted into the hollow portion of the fixing sleeve 1 in the bus X direction (FIG. 5) of the fixing sleeve 1. An exciting coil 3 is wound around the outer circumference of the magnetic core 2. The magnetic core 2 has a cylindrical shape and is arranged substantially in the center of the fixing sleeve 1 by a fixing means (not shown). The magnetic core 2 has a role of guiding the magnetic field lines of the alternating magnetic field generated by the exciting coil 3 into the inside of the fixing sleeve 1 and forming a passage of the magnetic field lines. The material of the magnetic core 2 is preferably a material having a small hysteresis loss and a high relative magnetic permeability, for example, a ferromagnetic material having a high magnetic permeability such as calcined ferrite or a ferrite resin.

It is desirable that the magnetic core 2 has a cross-sectional area as large as possible within a range that can be stored in the hollow portion of the fixing sleeve 1. In this embodiment, the diameter of the magnetic core is 5 mm to 40 mm, and the length in the longitudinal direction is 230 to 300 mm.

The exciting coil 3 is formed by spirally winding 20 turns of a copper wire having a diameter of 1 to 2 mm coated with a heat-resistant polyamide-imide around a magnetic core 2. Since the exciting coil 3 is wound around the magnetic core 2 in a direction intersecting the bus direction X of the fixing sleeve 1, when a high frequency current is passed through the exciting coil 3, an alternating magnetic field is generated in the direction along the bus direction X. Can be generated.

FIG. 6 is a conceptual diagram of the coil shape and the core shape. The moment when the current is increasing in the direction of arrow I1 is shown. The magnetic core 2 functions as a member that guides the magnetic field lines generated by the exciting coil 3 into the fixing sleeve 1 and forms a magnetic path. In the figure, S is a diagram of a circuit simulating only a part of the fixing sleeve 1. The heat generation principle of the fixing sleeve 1 follows Faraday's law. Faraday's law states, "When the magnetic field in the circuit S is changed, an induced electromotive force that tries to pass a current in the circuit is generated, and the induced electromotive force is proportional to the time change of the magnetic flux that penetrates the circuit vertically. To do. "

Consider a case where the circuit S is placed at the center of the magnetic core 2 shown in FIG. 6 and high-frequency alternating current is passed through the coil 3. When high-frequency alternating current is applied, an alternating magnetic field is formed around the coil. At that time, the induced electromotive force generated in the circuit S is proportional to the time change of the magnetic flux penetrating vertically according to the following equation (1).

V: Inductive electromotive force N: Number of coil turns ΔΦ / Δt: Change in magnetic flux that vertically penetrates the circuit in a minute time Δt When the circuit S is closed (closed circuit), a large current flows and the circuit S has. Joule heat is generated depending on the resistance value.

The technical gist of the present invention is to form a circuit S by combining conductive paths constituting the heat generating layer 1a and to heat a toner image (image) by utilizing Joule heat generation. The details of the method of combining the conductive paths will be described in detail in the following sections. When the circuit S is open (open circuit), although a voltage is applied, no current flows and Joule heat generation does not occur, so that the heat generating device cannot be established.

(6) Detailed Description of Conductive Path FIG. 7 (A) is a perspective view illustrating an outline of the shape of the first conductive path 1a1. The base layer 1a3 has a cylindrical shape having a radius r and a length L in the generatrix direction X of the base layer 1a3 . The first conductive path 1a1 is formed in a spiral shape so that the spiral axis is in the direction along the generatrix direction X of the base layer 1a3. Solid spiral 1a1 which is a first conductive path indicates the front side of the cylinder, the dotted line indicates the portion invisible rear side of the cylinder.

FIG. 7B is an enlarged view of the region D in FIG. 7A and viewed from the front.
Lp indicates the length in the generatrix direction X of the region provided with one circumference of the spiral 1a1. The relationship between the spiral angle and the number of turns will be described in detail. First, in the first conductive path 1a1 of FIG. 7 ( B ), a right triangle is drawn with a quarter circumference of the base layer 1a3 as one side, and the lengths of the sides of the triangle are a, b, r, and angles, respectively. Is θ1 . The following relationship exists between the length Lp and triangle of side b.

Lp = b × 4 ... (6-1)
Next, each side of the triangle has the following relationship,
b = a × cos θ ₁ ... (6-2)
r = a × sin θ ₁ ... (6-3)
Eliminating a from both equations gives the following.

b = rcosθ ₁ / sinθ ₁ ... (6-4)
Drunk length Lp is as (6-1) and (6-4) or less from the (6-5).

Lp = 4rcosθ ₁ / sinθ ₁ ... (6-5)
The number of turns N1 of the spiral 1a1 in the entire fixing sleeve is as follows (6-6).

_{N 1 = L / L p =} Lsinθ 1 / 4rcosθ 1 ····· (6-6)
In this embodiment, the angle θ ₁ = 88 ° of the spiral 1a1 which is the first conductive path, and the number of spiral turns N ₁ = 110. It is desirable that the number of turns is sufficiently narrow so that spiral thermal unevenness does not occur in the fixed image. In the configuration of this embodiment, the interval is preferably 1 mm or less and the number of turns is 110 or more. Further, the condition for drawing a spiral is that N1> 1 is satisfied. If L = 230 mm and r = 15 mm and θ ₁ = 14 °, then N ₁ = 1. Therefore, the condition for drawing a spiral is that θ = 14 ° or more when L = 230 mm and r = 15 mm.

Next, the second conductive path 1a2 will be described. If only the first conductive path 1a1 is used, the open circuit described in the heating principle of item (5) is formed, so that no current flows and heat cannot be generated. Like the first conductive path 1a1, the second conductive path shown by the thin line 1a2 in FIG. 1 is spirally formed so that the spiral axis is in the direction along the generatrix direction X of the base layer 1a3. The angle of the spiral was set to θ ₂ = −88 ° with respect to θ ₁ = 88 °, and was shaped to orbit in the direction opposite to the first conductive path 1a1. The first conductive path 1a1 and the second conductive path 1a2 are in contact with each other and are conducting at the circled portions, and form a current loop indicated by an arrow R.

That is, the spiral 1a2 which is the second conductive path intersects the spiral 1a1 which is the first conductive path, and is electrically conductive at the intersection with the spiral 1a1. Therefore, by contacting and conducting both the first conductive path 1a1 and the second conductive path 1a2, the closed circuit described in the section (5) can be formed, and a current flows due to the voltage in the circumferential direction. Can generate heat.

FIG. 8A is a method of forming the first conductive path 1a1 in the configuration of this embodiment. The cylindrical base layer 1a3 constituting the heat generating layer 1a is inserted into the columnar core body 81, and the discharge port 83 of the conductive paint supply unit 82 is brought into contact with the outer surface of the base layer 1a3. The conductive paint is continuously supplied from the discharge port 83 of the conductive paint supply unit 82, and the supply unit 82 is relatively moved in the direction of the arrow in the rotation axis direction of the core body 81. As a result, the conductive paint is spirally applied to the outer peripheral surface of the base layer 1a3 to form the first conductive path 1a1. The rotational speed and the moving speed may be determined to be optimum values for the formation angle θ1 of the spiral 1a1 as the first conductive path (the spiral 1a2 is θ2 ) .

As the conductive coating material, known materials such as metals such as steel, aluminum, copper and silver, and fine particle powders of conductive materials such as carbon black dispersed in a binder resin can be used.

Next, when the second conductive path 1a2 is formed, the core body 81 is rotated in the circumferential direction of the arrow as shown in FIG. 8B. Further, the conductive paint supply portion 82 is relatively moved in the direction of the arrow in the rotation axis direction of the core body 81. As a result, the conductive paint is spirally applied to the outer peripheral surface of the base layer 1a3 on which the first conductive path 1a1 is already formed, and the second conductive path 1a2 is formed.

As a result, both the first conductive path 1a1 and the second conductive path 1a2 come into contact with each other and conduct with each other, so that the closed circuit described in the section (5) can be formed, and a current in the circumferential direction flows to generate heat. You can.

In FIG. 8B, the thickness of the first conductive path 1a1 and the second conductive path 1a2 are changed in order to make it easier to distinguish, but this is the conductive paint coating width at the time of manufacture. Does not indicate.

After this coating step, when the spiral coating pattern with the conductive paint is heat-cured, the first and second conductive paths 1a1 and 1a2 are formed on the base layer 1a3. According to this manufacturing method, spirals 1a1 and 1a2, which are the first and second conductive paths, can be drawn with a uniform coating amount, and the line thickness and thickness of the conductive pattern can be uniformly manufactured as a whole. .. Further, there is an advantage that the angles of the spirals 1a1 and 1a2 can be freely adjusted by adjusting the rotation speed of the cylindrical core 81 and the moving speed of the conductive paint supply unit 82.

(Explanation of effect)
FIG. 9 is a schematic for explaining that when the heat generating layer 1a of the fixing sleeve 1 of this embodiment has a crack 1k which is a broken portion, the phenomenon that the fixing sleeve 1 overheats at the broken portion end C can be suppressed. It is a figure. FIG. 16 shows an example in which a fixing sleeve having a cylindrical conductive layer as a heat generating layer 1a is used for comparison. As the heat generating layer 1a, SUS304 was used, and the film thickness was 30 μm and the diameter was Φ30 mm. The elastic layer and the surface layer are the same as in Example 1.

As a method of the comparative experiment, the presence or absence of local heat generation when the damaged portion "Z2" was provided in a part of the sleeve in the longitudinal direction was compared. First, in the case of the present embodiment shown in FIG. 9, in the undamaged region “Z1”, a circumferential current flows in the closed circuit formed by the first conductive path 1a1 and the second conductive path 1a2. In the damaged region "Z2", since the closed circuit is not formed, the orbital current does not flow and heat is not generated. Further, since the current can flow only in the portion where the conductive pattern is the first conductive path 1a1 and the second conductive path 1a2, the current bypass as in the configuration of the comparative example shown in FIG. 16 does not occur. Therefore, the temperature of the end portion C of the crack 1k does not rise abnormally.

In the case of the comparative example shown in FIG. 16, in the non-damaged region “Z1”, an induced electromotive force is generated in the closed circuit created by the fixing sleeve, and a current flows in the circumferential direction as shown by an arrow. In the damaged region "Z2", the current flowing in the circumferential direction bypasses, and the current flows around the damaged end. A large amount of current flows to the damaged end, resulting in an excessive temperature rise compared to other regions.

Therefore, the overheating did not occur in principle in the configuration of the first embodiment, and the prevention of the local overheating in the crack generation state was achieved.

Other means for realizing the configuration of this embodiment will be described. (A) in FIG. 10 is obtained by reducing the angle theta ₂ in relation to the angle theta ₁ and theta _2. Also in this case, since the first and second conductive paths 1a1 and 1a2 can be joined at the portion marked with a circle to form the closed circuit indicated by the arrow R, the same effect as that of the first embodiment can be obtained.

FIG. 10B shows the angle of θ _{2 set} to 0 °. Also in this case, the conductive paths 1a1 and 1a2 can be joined at the portion marked with a circle to form the closed circuit L indicated by the arrow R. Therefore, the same effect as in Example 1 can be obtained. Further, since the amount of the conductive coating material can be reduced, it is advantageous in terms of cost.

However, as shown in FIG. 11, if θ ₁ = θ ₂ and there is no junction between the first and second conductive paths 1a1 and 1a2, a closed circuit cannot be formed, and the effect of this configuration is effective. It cannot be obtained and heat cannot be generated. Therefore, it is not included in the configuration of the present invention.

In addition, another feature of this embodiment is that the variation in the circumferential resistance value of each closed circuit can be reduced. FIG. 12 shows a configuration in which the conductive paths 1a4 are connected in a ring shape and formed as a comparative example. This is a case where the variation of the circuit resistance of the closed circuit becomes large.

In this case, the manufacturing method is that the conductive paint supply unit 82 is stopped, the discharge port 83 is brought into contact with the outer surface of the cylindrical base layer 1a3, and the core body 81 is rotated in the circumferential direction of the arrow while being conductive. The paint is supplied from the supply unit 82, and the conductive path 1a4 is formed once. After forming one round, the supply of the conductive paint is stopped, the discharge port 83 is separated from the base layer 1a3 to be non-contact, and the supply unit 82 and the discharge port 83 are oriented in the direction of the broken line arrow in the rotation axis direction of the core body 81. Move by a predetermined distance. Then, at the next location, the conductive paint is supplied from the supply unit 82 while the discharge port 83 is brought into contact with the base layer 1a3 and the columnar core body 81 is rotated in the circumferential direction of the arrow to form the conductive path 1a4 once. ..

The above steps are repeated to form a large number of closed-loop conductive paths 1a4. In this case, since the supply and stop of the conductive coating material and the contact and non-contact of the discharge port 83 are repeated many times, the coating amount tends to vary. Since a closed circuit can be formed, it is possible to generate heat. However, it is desirable that the variation in the circuit resistance of the closed circuit is as small as possible because the amount of heat generated varies.

Since the conductive paint supply unit 82 and the discharge port 83 are repeatedly moved and stopped, variations in the pattern intervals of the conductive paths 1a4 are likely to occur. If the pattern spacing varies, heat unevenness occurs in the longitudinal direction, which deteriorates the print quality of the fixed image.

On the other hand, in the configuration of the first embodiment, the method of applying the conductive paths 1a1 and 1a2 to the spiral pattern while continuously supplying the conductive paint reduces the variation in the circumferential resistance of the closed circuit and the pattern interval. It is advantageous because the variation of the can be reduced.

<< Example 2 >>
The second embodiment is characterized in that a conductor braided wire is used as the conductive path. The conductor braided wire can be manufactured by knitting a large number of conductor wires such as a thin copper wire using a braiding machine or the like which is widely used in a coaxial cable or the like.

FIG. 13 is a conceptual diagram of a conductor braided wire 1e1 serving as a first conductive path and a conductor braided wire 1e2 serving as a second conductive path wound around the outer peripheral surface of a cylindrical base layer 1a3 constituting the heat generating layer 1a. is there. That is, in the fixing sleeve 1 of this embodiment, the first conductive path 1e1 and the second conductive path 1e2 constituting the heat generating layer 1a are formed of conductive fibers.

Similar to the first conductive path 1a1 and the second conductive path 1a2 of FIG. 1 in the first embodiment, the first conductive path 1e1 and the second conductive path 1e2 have contacts at the portions marked with ○ and ● and orbit. The loop R can be formed. Therefore, heat can be generated. Examples of the material of the conductor wire (conductive fiber) include stainless steel, nickel, and copper fiber, but stainless steel having a thickness of 50 μm is preferable from the viewpoint of material price, corrosion resistance, strength, and the like.

Further, the conductor braided wire and the insulator wire may be combined and knitted for the purpose of narrowing the gap between the braided wires and imparting rigidity. For example, in the configuration shown in FIG. 14, in the first conductive path 1e1, one conductor wire 1e1A shown by a solid line and three insulator wires 1e1B shown by a dotted line are combined and knitted in the same direction. Similarly, in the second conductive path 1e2, one conductor wire 1e2A shown by a solid line and three insulator wires 1e2B shown by a dotted line are knitted in combination.

That is, in the fixing sleeve 1 of this embodiment, the first conductive path 1e1 and the second conductive path 1e2 constituting the heat generating layer 1a are formed of composite fibers 1e1A / 1e1B and 1e2A / 1e2B containing conductive fibers. The merit in this case is that the higher the fiber density, the higher the rigidity of the braided wire, and the lower the heat capacity can be obtained by omitting the base layer 1a3. The material of the insulator wire is preferably polyimide or polyamide resin having excellent heat resistance. From above, the elastic layer and the surface layer are formed in the same manner as in Example 1.

(Explanation of effect)
Compared to the configuration of Example 1, the configuration of this Example 2 forms a closed circuit using stainless steel, nickel, copper fiber, etc., which have been widely used conventionally, so that the circumferential resistance varies. It can be made smaller than the above configuration, which is advantageous in improving the print quality.

<< Example 3 >>
The fixing sleeve 1 of the third embodiment uses a mixed woven fabric in which a plurality of yarns composed of a circumferential yarn and a longitudinal yarn are plain-woven into a cylindrical shape as a conductive path. More specifically, as shown in FIG. 15, a thread in which 1 g1 of a metal fiber thread is wound in a spiral direction and a thread in which an electrically insulating heat-resistant resin thread 1 g2 is formed in a longitudinal direction are formed by weaving. is there. Then, at least one 1 g2A of the weft threads is formed of threads made of metal fibers.

A cylindrical net body having 1 g1 of a metal fiber as a warp is formed in a spiral shape with an interval of 0.5 mm and 460 turns, and the material of the thread includes stainless steel fiber, nickel fiber, copper fiber and the like. In this case, a stainless steel fiber having a thickness of 50 μm is preferable from the viewpoint of material price, corrosion resistance, strength and the like. The spirally wound warp threads are not in contact with each other. Heat-resistant resin fibers are suitable for the wefts formed in the longitudinal direction, and mainly polyimide resin yarns having a diameter of 50 μm can be used. The mixed woven fabric plain weaved by the combination of the warp and the weft can form the first conductive path 1a1 shown in FIG. 7 of the first embodiment.

On the other hand, a part of the weft yarn formed in the longitudinal direction is made of stainless steel yarn 1g2A. Since the warp and the weft are in contact with each other in combination, it is possible to form the same second conductive path as shown in FIG. 10 in which θ ₂ = 0 ° by conducting electrical conduction. Therefore, the closed circuit R shown in FIG. 10 (B) of the first embodiment can be formed, and heat can be generated.

(Explanation of effect)
Similar to the configuration of the second embodiment, the configuration of the third embodiment forms a closed circuit using stainless steel, nickel, copper fiber, etc., which have been widely used conventionally, so that the variation of the circumferential resistance is different from the configuration of the first embodiment. Can be further reduced, which is advantageous in improving the print quality. Since it can be manufactured using a plain weave machine that has been widely used conventionally, it is easy to increase the number of laps N of the first conduction path, which is advantageous in improving print quality.

<< Other matters >>
1) The tubular heating rotating body having a conductive layer may be in the form of a flexible endless belt that is suspended and rotationally driven between a plurality of tensioning members. Further, the tubular heating rotating body having the conductive layer may be in the form of a hollow roller or a pipe.

2) The image heating device is not limited to the fixing device of the embodiment. The image heating device also includes a glossiness imparting device that improves the glossiness of an image by heating a toner image fixed on a recording material.

A ... image heating device, 1 ... heating rotating body, 1a ... conductive layer, 1a1 ... first conductive path, 1a2 ... second conductive path, 2 ... core, 3 ... coil, P ...・ Recording material, T ・ ・ Image

Claims (10)

The conductive layer has a tubular heating rotating body having a conductive layer and a spiral-shaped portion arranged inside the heating rotating body and having a spiral axis extending in a direction along the generatrix direction of the heating rotating body. A coil for forming an alternating magnetic field for electromagnetic induction heat generation and a magnetic core arranged in the spiral shape portion for inducing magnetic field lines of the alternating magnetic field are provided to heat a recording material on which an image is formed. The heating rotating body used in the image heating device to be used.
The conductive layer, said first conductive path helical axis is the first conductive path adjacent in and the generatrix direction becomes the direction along the generatrix direction is formed in a spiral shape so as not to contact the first crosses the conductive path, have a, a second conductive path is conducting the first conductive path electrically at the location of the intersecting said first conductive path, said A heating rotating body, characterized in that a closed circuit through which an induced current due to the alternating magnetic field flows is formed by the first conductive path and the second conductive path . The heating rotating body according to claim 1, wherein the second conductive path draws a spiral at an angle different from that of the first conductive path. The heated rotating body according to claim 1 or 2, wherein the first conductive path and the second conductive path are patterned with a conductive paint. The heated rotating body according to claim 1 or 2, wherein the first conductive path and the second conductive path are formed of conductive fibers. The heated rotating body according to claim 1 or 2, wherein the first conductive path and the second conductive path are formed of composite fibers containing conductive fibers. The conductive layer has a tubular heating rotating body having a conductive layer and a spiral-shaped portion arranged inside the heating rotating body and having a spiral axis extending in a direction along the generatrix direction of the heating rotating body. A coil for forming an alternating magnetic field for electromagnetic induction heat generation and a magnetic core arranged in the spiral shape portion for inducing magnetic field lines of the alternating magnetic field are provided to heat a recording material on which an image is formed. In the image heating device
The conductive layer, said first conductive path helical axis is the first conductive path adjacent in and the generatrix direction becomes the direction along the generatrix direction is formed in a spiral shape so as not to contact the first crosses the conductive path, have a, a second conductive path is conducting the first conductive path electrically at the location of the intersecting said first conductive path, said An image heating device, characterized in that a closed circuit through which an induced current due to the alternating magnetic field flows is formed by the first conductive path and the second conductive path . The image heating device according to claim 6, wherein the second conductive path draws a spiral at an angle different from that of the first conductive path. The image heating device according to claim 6 or 7, wherein the first conductive path and the second conductive path are formed by coating a conductive paint. The image heating apparatus according to claim 6 or 7, wherein the first conductive path and the second conductive path are formed of conductive fibers. The image heating device according to claim 6 or 7, wherein the first conductive path and the second conductive path are formed of composite fibers containing conductive fibers.