JP3575214B2 - Heating roller device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating roller device including a heating roller in a fixing device for heating and fixing an unfixed image such as a toner image on a recording material holding the image in an image forming apparatus such as an electrophotographic copying machine or a printer.
[0002]
[Prior art]
A fixing device in an electrophotographic image forming apparatus such as a printer or a copying machine generally includes a heating roller, and a recording material holding an unfixed image such as a toner image is transferred to the heating roller and a backup member ( Generally, the unfixed image is heated and pressed on a recording material to fix the unfixed image by being sandwiched and passed between the recording material and a pressure roller.
[0003]
Hitherto, a heating roller having a built-in heating heater such as a halogen lamp heater and heating the roller with radiant heat from the heater has been widely used.
However, according to the heating roller that uses a built-in heating heater such as a halogen lamp heater as a heat source, the rate of temperature rise from the start of energization of the heater to a predetermined fixing temperature on the surface of the heating roller is slow, so that the power switch of the image forming apparatus is turned on. The pre-heating time (so-called warm-up time) from when the heating roller reaches the predetermined temperature to the predetermined temperature becomes longer, and the apparatus becomes more difficult to use.
[0004]
Therefore, a heating roller has been proposed in which a resistance heating element made of a substance that generates heat by energizing the core roller is formed so as to rotate together with the core roller, as a heating roller that requires a short time for raising the temperature to reach a predetermined temperature. This type of heating roller has good electric / heat conversion efficiency and can raise the surface temperature of the heating roller to a predetermined temperature immediately after the energization of the resistance heating element, thereby shortening the preheating time of the heating roller. Can be.
[0005]
In the heating roller of this type, in order to energize the resistance heating element, generally, a power receiving member that is electrically connected to the resistance heating element and rotates together with the heating roller, and a power supply member that is brought into contact with the power receiving member Are provided, and the resistance heating element is energized through them.
For example, a power receiving member is provided so as to rotate integrally with the roller at both ends in the rotation center axis direction of the core roller serving as a core material of the heating roller, and a power supply member is brought into contact with each of the power receiving members from the outside in the axial direction. Heat rollers have been proposed. Such a power receiving member is generally provided with a circular plane centered on the rotation center of the core roller for contact with the power supply member, and similarly, the power supply member is provided with a circular plane for contact with the power reception member. Have been. The power supply member is arranged such that the center of the circular plane for contact with the power receiving member is aligned with the rotation center of the circular plane for contact with the power supply member of the power receiving member, and is usually directed toward the power receiving member by a spring or the like. Pressed. Thus, the power receiving member and the power supply member are in surface contact with each other. The power supply member is usually made of carbon or a carbon-containing material. As a result, when the core roller rotates and the power receiving member rotates integrally therewith, the power supply member is shaved by the sliding of the power receiving member, a carbon film is formed on the mutual contact surface, and the contact on the contact surface is reduced. Resistance can be reduced.
[0006]
[Problems to be solved by the invention]
However, in order to energize the resistance heating element, the power receiving members are attached to both ends of the core roller in the axial direction of the roller rotation center, and the heating roller in which the carbon power supply member contacts from the outside in the axial direction, on the recording material. When the heating roller (core roller) is driven to rotate at the time of heating and fixing the held unfixed toner image, the power receiving member rotates integrally with the core roller, and the power receiving member and the power supply member are brought into contact with each other at their mutual contact surfaces. Although the sliding contact occurs, the peripheral speed of the surface of the power receiving member for contact with the power supply member differs greatly in the direction of the radius of rotation. Since the peripheral speed is higher than the peripheral speed of each part, the contact state of each part with the power supply member is different. Therefore, on these mutual contact surfaces, the carbon film is less likely to be formed at the center portion in the radial direction of rotation than at the outer edge portion in the radial direction of rotation, so that the outer edge portion and the central portion have a contact resistance with the power supply member or a resistance of itself. Inconveniences such as a large fluctuation occur. Further, if the unevenness in the radial direction of the carbon film formed on the mutual contact surface between the power supply member and the power receiving member progresses, a spark is generated or heat generation at the mutual contact surface increases. This makes it impossible to apply a stable voltage to the resistance heating element.
[0007]
Therefore, the present invention is a heating roller device including a heating roller of a fixing device that heats and fixes an image on a recording material holding an unfixed image, and a core roller that constitutes the heating roller has resistance heating for roller heating. A power receiving member attached to both ends of the roller in the direction of the rotation center axis for energizing the resistance heating element and rotating integrally with the core roller; and A heating roller device having a carbon-made power supply member to be pressed against, wherein a uniform carbon film can be formed on the mutual contact surface between the power reception member and the power supply member, whereby the resistance variation and the contact on the mutual contact surface can be improved. It is an object of the present invention to provide a heating roller device capable of reducing resistance and stably energizing a resistance heating element.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is a heating roller device of a fixing device that heats and fixes an image on a recording material holding an unfixed image, and includes a core roller, an outer peripheral surface of the core roller, and / or an inner roller. A resistance heating element that is formed along the peripheral surface and rotates together with the core roller, and is electrically connected to the resistance heating element and generates heat when energized, and is attached to both ends of the core roller in the rotation center axis direction, A heating roller including a pair of power receiving members that rotate together with the core roller, and a pair of carbon power supply members that are pressed against the respective power receiving members from outside the rotation center axis direction of the core roller toward the power receiving members and abut thereon. A heating roller device, wherein the power supply member has a surface in contact with the power receiving member formed on a surface with a central portion vacant, and is in contact with a rotation radial direction external region in the power receiving member. Offer To.
[0009]
The carbon power supply member is made of carbon or a carbon-containing material, and can be made of, for example, copper-based carbon or silver-based carbon.
The power receiving member may be made of a conductive material, for example, brass, iron, or copper.
The power receiving member has a surface for contacting the power supply member, and the power supply member also has a surface for contacting the power receiving member. These surfaces are in surface contact with each other, but the surface of the power supply member for contact with the power receiving member is a surface with an empty center portion, and the surface of the power reception member for contact with the power supply member in the core roller rotation radial direction. (In other words, it contacts only the outer region of the power receiving member rotating integrally with the core roller in the rotational direction), that is, these surfaces do not contact at the radial center portion.
[0010]
In order to make the power supply member contact only the outer region in the rotation radial direction of the power reception member in this manner, for example, the following (1) or (2) may be used.
{Circle around (1)} The power receiving member is substantially orthogonal to the rotation center axis direction of the core roller (in other words, the rotation center axis direction of the power reception member rotating integrally with the core roller) for contacting the power feeding member. The power supply member is provided with a ring-shaped flat surface for making contact with the power receiving member, and the ring-shaped flat surface of the power supply member is formed such that the center thereof is the power receiving member. Is brought into contact with the circular plane so as to substantially coincide with the center of the circular plane. The ring-shaped plane of the power supply member is provided, for example, by providing a circular concave portion at the center of the circular plane at one end of the columnar member, or by providing a circular hole penetrating from the center of the circular plane at one end of the columnar member to the other end surface. Can be formed. In this case, the ring-shaped plane of the power supply member may be divided into two or more, preferably three (more preferably, equally divided) at a predetermined center angle interval.
{Circle around (2)} The power receiving member is provided with a convex conical surface which is inclined with respect to the direction of the rotation center axis of the core roller and is substantially coincident with the center of the rotation center axis for contact with the power supply member. The member is provided with a ring-shaped concave conical surface that is in contact with the convex conical surface of the power receiving member for contact with the power receiving member, and the center of the ring-shaped concave conical surface of the power supply member is the power receiving member. Is brought into contact with the convex conical surface so as to substantially coincide with the center of the convex conical surface. Note that the “conical surface” when referring to the convex conical surface of the power receiving member refers to a conical surface of a cone, and may be a part of the conical surface that does not include the apex of the cone. Further, the “conical surface” when referring to the concave conical surface of the power supply member refers to the conical surface of a pot-shaped member that is depressed in a conical shape. Since the concave conical surface of the power supply member is ring-shaped, it is a partial conical surface that does not include the apex of the cone. The ring-shaped concave conical surface of the power supply member can be formed, for example, by first providing a concave conical surface from one end surface of the columnar member, and then providing a circular concave portion or a circular through hole in a portion including the conical apex. Also in this case, the ring-shaped concave conical surface of the power supply member may be divided into two or more, preferably three (more preferably, equally divided) at predetermined center angle intervals.
[0011]
In the heating roller device of the present invention, when the resistance heating element is energized via the power supply member and the power receiving member, the resistance heating element generates heat and heats the heating roller. When the heating roller is driven to rotate at the time of heat fixing of an unfixed image or the like, the power receiving member rotates integrally with the core roller, and the power receiving member slides relative to the power feeding member, and the mutual movement of the power receiving member and the power feeding member is caused. At the contact surface, the power supply member is shaved to form a carbon film. At this time, only the outer region in the rotational radius direction, which has a higher peripheral speed than the central portion in the rotational radial direction of the power receiving member, slides with respect to the power supply member. Because of this, a uniform carbon film is easily formed, so that the contact resistance at these mutual contact surfaces is reduced, and the fluctuation of the contact resistance is suppressed. Can be.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic sectional view of an example of a fixing device having a heating roller device according to an embodiment of the present invention. The fixing device heats and fixes an unfixed toner image on a sheet-shaped recording material holding the toner image.
[0013]
The fixing device includes a heating roller device including the heating roller 1 and the like according to the present invention, and a pressure roller 2 facing the heating roller 1.
The heating roller 1 is rotatably supported at both ends by bearings 31 supported by a fixing device housing H. The heating roller 1 is driven to rotate by driving means (not shown).
[0014]
The pressure roller 2 is rotatably supported by supporting means (not shown), and is pressed toward the heating roller 1 by pressing means (not shown) such as a spring or an elastic body. The pressure roller 2 rotates following the rotation of the heating roller 1 or following the movement of the recording material passed between the two rollers.
The heating roller 1 has a hollow cylindrical core roller 10 (in this example, made of an aluminum alloy), and has an insulating layer 11 and a layered resistance heating element (hereinafter referred to as a resistance heating layer) on the inner peripheral surface of the core roller 10. .) 12 are sequentially formed, and a release layer 13 is formed on the outer peripheral surface.
[0015]
The insulating layer 11 is formed between the resistance heating layer 12 and the core roller 10 in order to maintain electrical insulation between them. In this example, the insulating layer 11 is made of a heat-resistant insulating resin polyimide.
The resistance heating layer 12 generates Joule heat by itself when energized, and in this example is made of a barium titanate-based ceramic.
[0016]
When the recording material holding the unfixed toner image passes while being sandwiched between the heating roller 1 and the pressure roller 2 opposed thereto, the release layer 13 removes the heated toner image from the heating roller 1. It is formed so as to be easily peeled off from, and in this example, is made of polytetrafluoroethylene.
The insulating layer 11, the resistance heating layer 12, and the release layer 13 rotate integrally with the core roller 10.
[0017]
Power receiving members 141 are attached to both ends of the heating roller 1 in the rotation center axis direction. Although not limited thereto, it is fitted on the inner peripheral surface side of the core roller 10 here. Each power receiving member 141 is a hat-shaped member having a circular flat surface 1411 whose center line coincides with the rotation center axis of the roller 1 and is substantially orthogonal to the rotation center axis direction, and is made of a conductive material such as brass. Each power receiving member 141 is adhered and fixed to the resistance heating layer 12 with a conductive adhesive, and is electrically connected to the heating layer 12. The power receiving member 141 rotates integrally with the core roller 10.
[0018]
The power supply members 51 made of a carbon-containing conductive material, for example, copper-based carbon, are in contact with the circular flat surface 1411 of each power receiving member 141 from the outside in the rotation center axis direction of the heating roller 1. The power supply member 51 may be made of silver-based carbon.
FIG. 2A is a perspective view of the power supply member 51, and FIG. 2B is a cross-sectional view thereof.
[0019]
The power supply member 51 has a ring-shaped flat surface 511, and a portion surrounded by the ring-shaped flat surface 511 is a circular concave portion 512. In other words, a ring-shaped flat surface 511 is formed on the power supply member 51 by the concave portion 512. A ring-shaped flat surface 511 faces the circular flat surface 1411 of the power receiving member 141 such that the center thereof is aligned with the center of the circular flat surface 1411.
[0020]
Each power supply member 51 is pressed toward the power receiving member 141 under an appropriate pressure by a pressing unit such as a spring (not shown). Thus, even when the power receiving member 141 rotates integrally with the core roller 10, the electrical connection between the power receiving member 141 and the power supply member 51 is maintained. The left power supply member 51 is electrically connected to one end of the power supply 4, and the right power supply member 51 is connected to the other end of the power supply 4 via a contact of the solid state relay SSR. By closing, it is possible to energize the resistance heating layer 12 (see FIG. 1).
[0021]
The contact of the relay SSR can be opened and closed by a control unit CTR including a central processing unit (CPU) that controls the operation of the entire fixing device. The control unit CTR opens and closes the relay SSR based on the temperature of the heating roller 1 detected by the thermistor TH which is a temperature detecting element abutting on the outer peripheral surface of the release layer 13 of the heating roller 1.
According to the fixing device described above, the fixing of the toner image on the recording material holding the unfixed toner image is performed as follows. That is, the contact of the relay SSR is closed by the control unit CTR, and a voltage is applied from the power supply 4 to the resistance heating layer 12 via the power supply member 51, the power receiving member 141, and the like, whereby the resistance heating layer 12 generates Joule heat. The heating roller 1 is heated from the inner peripheral surface side. By using a resistance heating element as a heating source of the heating roller 1, the temperature of the heating roller 1 quickly rises. At this time, energization control is performed based on the temperature of the heating roller 1 detected by the thermistor TH, and the heating roller 1 is maintained at a predetermined fixing temperature. The heating roller 1 is rotationally driven by a driving unit (not shown), and the recording material is passed between the heating roller 1 having a fixing temperature and the pressure roller 2 pressed against the heating roller 1, thereby causing the recording material to pass over the recording material. Is fixed under heat and pressure.
[0022]
In the heating roller device including the heating roller 1 and the like of the present invention, since the power supply member 51 is formed of a copper-based carbon material, the heating roller 1 (core roller 10) is driven to rotate, and the power receiving member 141 is connected to the core roller 10. When integrally rotated, the power supply member 51 and the power receiving member 141 slide with each other, and a carbon film is formed on their mutual contact surfaces. At this time, by forming the flat surface 511 of the power supply member 51 that is the contact surface with the power receiving member circular flat surface 1411 in a ring shape, only the outer peripheral region in the rotational radial direction where the peripheral speed is faster than the central portion in the rotational radial direction of the circular power receiving member 1411 is used. However, since the carbon film slides with respect to the power supply member 51, such a carbon film is easily formed, so that the contact resistance at these mutual contact surfaces is reduced, and the circumferential speed of the power receiving member 141 becomes substantially the same. Since only the region slides with respect to the power supply member 51, such a carbon film becomes uniform, and the fluctuation of the contact resistance at the mutual contact surface is suppressed accordingly, so that a stable voltage application to the resistance heating layer 12 can be performed. it can. In other words, in this heating roller device, the peripheral speed is relatively high and the peripheral speed is substantially equal in the rotational radius direction of the circular plane 1411 of the power receiving member, and the carbon film is uniformly formed by sliding with the power supply member 51. The surface of the power supply member 51 that is to be in contact with the power receiving member circular flat surface 1411 is provided with a concave portion 512 at the center portion in the rotation radial direction so that the power supply member 51 does not come into contact with the power supply member 51 so that the power supply member 51 comes into contact only with the portion that is likely to be contacted. Only the ring-shaped flat surface 511 serving as the outer edge portion is brought into contact.
[0023]
The portion of the power supply member 51 surrounded by the ring-shaped flat surface 511 may be a through hole 513 as shown in FIG.
Further, instead of the power supply member 51 shown in FIG. 2, a power supply member 52 shown in FIG. 4 may be employed. 4A is a perspective view showing another example of the power supply member, FIG. 4B is a side view of the power supply member, and FIG. 4C is a front view of the power supply member.
[0024]
The power supply member 52 shown in FIG. 4 has three planes 521A, 521B, and 521C on the same plane, and each of these planes is a circular arc that forms a part of a ring-shaped plane. The two planes are generally ring-shaped. A portion surrounded by these three planes is a recess 522. The shape of the power supply member 52 is such that the ring-shaped flat surface 511 of the power supply member 51 shown in FIG. 2 is equally divided into three.
[0025]
The power supply member 52 is arranged such that the three planes 521A, 521B, and 521C are in contact with the power receiving member 141 such that their centers coincide with the centers of the circular flat surfaces 1411 of the power receiving member 141. Only the outer region in the radial direction of rotation having a higher peripheral speed than the central portion in the rotational radial direction of the circular flat surface 1411 slides with respect to the power supply member 52, and only the portion having substantially the same peripheral speed is applied to the power supply member 52. Therefore, as in the case of the power supply member 51 shown in FIG. 2, a uniform carbon film is easily formed on these mutual contact surfaces. Further, since the surface of the power supply member 52 that contacts the power receiving member 141 is divided into three, the power supply member 52 is pressed against the power receiving member 141 in a stable posture.
[0026]
FIG. 5 is a schematic sectional view of another example of the fixing device having the heating roller device of the present invention. This fixing device employs a power receiving member 142 in place of the power receiving member 141 and a power supply member 53 in place of the power supply member 51 in the fixing device shown in FIG. 1, and other parts are substantially the same. Therefore, the power receiving member 142 and the power supply member 53 will be described below. The parts having the same function are denoted by the same reference numerals as those in FIG. FIG. 6A is a perspective view of the power receiving member 142, FIG. 6B is a perspective view of the power supply member 53, and FIG. 6C is a cross-sectional view of the power supply member 53.
[0027]
The power receiving member 142 has a convex conical surface 1421 that is an inclined surface inclined with respect to the rotation center axis of the core roller 10. The convex conical surface 1421 is a part of the conical surface of the cone that does not include the cone apex. The convex conical surface 1421 coincides with the center axis of rotation of the core roller 10, and is electrically connected to the resistance heating layer 12. The power receiving member 142 rotates integrally with the core roller 10.
[0028]
The power supply member 53 has a ring-shaped concave conical surface 531 of a shape fitted to the convex conical surface 1421 of the power receiving member 142, and a central portion surrounded by the ring-shaped concave conical surface 531 is a concave portion 532. The power supply member 53 faces the power reception member 142 such that the centers thereof are aligned, and the power supply member 53 is pressed toward the power reception member 142 from the outside in the rotation center axis direction of the core roller 10, As a result, the ring-shaped concave conical surface 531 of the power supply member 53 and the convex conical surface 1421 of the power receiving member 142 are in contact with each other. Further, the power supply member concave portion 532 is provided at the central portion of the power supply member 53 and the power receiving member 142 in the rotational radius direction, and thus does not contact the central portion. That is, the power supply member 53 and the power receiving member 142 are not in contact with each other in the center portion in the rotation radial direction, but are in contact only in the outer region in the rotation radial direction.
[0029]
Also in this heating roller device, when the heating roller 1 is driven to rotate and the power receiving member 142 rotates integrally with the core roller 10, the power supply member 53 and the power receiving member 142 slide with each other, and their mutual contact surfaces. A carbon film is formed in the step. At this time, only the radially outer region having a higher peripheral speed than the radial center portion of the power receiving member convex conical surface 1421 slides on the ring-shaped concave conical surface 531 of the power supply member 53, and the power receiving member 142. Since only the portion having the same peripheral speed slides with respect to the power supply member 53, a uniform carbon film is formed, the contact resistance is reduced accordingly, and the fluctuation of the contact resistance is suppressed. Further, since the mutual contact surface between the power supply member 53 and the power receiving member 142 is inclined with respect to the rotation center axis direction of the power reception member 142 (or a surface orthogonal to the rotation center axis direction), the center of the power supply member 53 is centered. The deviation from the rotation center of the power receiving member 142 is suppressed, and the voltage can be applied to the resistance heating layer 12 more stably.
[0030]
The portion of the power supply member 53 surrounded by the ring-shaped concave conical surface 531 may be a through hole 533 as shown in FIG.
4, the ring-shaped concave conical surface 531 of the power supply member 53 may be divided into two or more at predetermined center angle intervals.
In the heating roller 1 described above, the resistance heating layer is provided on the inner peripheral surface of the core roller, but may be provided on the outer peripheral surface or the inner and outer peripheral surfaces of the core roller.
[0031]
【The invention's effect】
According to the present invention, there is provided a heating roller device including a heating roller of a fixing device for heating and fixing an image to a recording material holding an unfixed image, and a core roller constituting the heating roller has a resistance heat for heating the roller. A power receiving member that is attached to both ends of the roller in the direction of the rotation center axis for energizing the resistance heating element and that rotates integrally with the core roller; A heating roller device having a carbon-made power supply member to be pressed against, wherein a uniform carbon film can be formed on the mutual contact surface between the power receiving member and the power supply member, whereby resistance variation and contact at the mutual contact surface can be formed. It is possible to provide a heating roller device capable of reducing the resistance and stably energizing the resistance heating element.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an example of a fixing device having a heating roller device of the present invention.
2A is a perspective view of an example of a power supply member of the heating roller device shown in FIG. 1, and FIG. 2B is a cross-sectional view of the power supply member.
3A is a perspective view of another example of a power supply member of the heating roller device shown in FIG. 1, and FIG. 3B is a cross-sectional view of the power supply member.
FIG. 4A is a perspective view of still another example of the power supply member, FIG. 4B is a side view of the power supply member, and FIG. 4C is a front view of the power supply member.
FIG. 5 is a schematic sectional view of another example of the fixing device having the heating roller device of the present invention.
6A is a perspective view of an example of a power receiving member of the heating roller device shown in FIG. 5, FIG. 6B is a perspective view of a power feeding member of the heating roller device shown in FIG. 5, and FIG. It is sectional drawing of a power supply member.
7A is a perspective view of another example of the power supply member of the heating roller device shown in FIG. 5, and FIG. 7B is a cross-sectional view of the power supply member.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 heating roller 10 core roller 11 insulating layer 12 resistance heating layer 13 release layer 141, 142 power receiving member 1411 circular flat surface 1421 of power receiving member 141 convex conical surface of power receiving member 142 2 pressure roller 31 bearing of heating roller 1 power supply 51, 52, 53 Power supply member 511 Ring-shaped plane 512 of power supply member 51 Concave portion 513 of power supply member 51 Through holes 521A, 521B, 521C of power supply member 51 Plane 522 of power supply member 52 Concave portion 531 of power supply member 52 Ring of power supply member 53 Concave surface 532 Concave portion 533 of power supply member 53 Through hole H of power supply member 53 Fixing device housing SSR Relay

Claims (5)

A heating roller device of a fixing device that heats and fixes the image on the recording material holding the unfixed image,
A core roller, a resistance heating element formed along the outer peripheral surface and / or the inner peripheral surface of the core roller, rotating together with the core roller, and generating heat when energized, and electrically connected to the resistance heating element; A heating roller attached to both ends of the core roller in the rotation center axis direction and including a pair of power receiving members that rotate with the core roller,
Each of the power receiving members has a pair of carbon power supply members that are pressed toward the power receiving member from the outside in the rotation center axis direction of the core roller and abut against the power receiving member,
The heating roller device according to claim 1, wherein the power supply member has a surface in contact with the power receiving member formed on a surface with a central portion vacant, and is in contact with a rotation radially outer region of the power receiving member. The power receiving member has a circular flat surface for contacting the power supply member and substantially perpendicular to a rotation center axis direction of the core roller and having a center substantially coincident with the rotation center axis. The ring-shaped plane of the power supply member has a center substantially aligned with the center of the circular plane of the power receiving member, and the ring-shaped plane of the power supply member is in contact with the circular plane. Heating roller device. 3. The heating roller device according to claim 2, wherein the ring-shaped plane of the power supply member is divided into two or more at a predetermined center angle interval. The power receiving member has a convex conical surface that is inclined with respect to the rotation center axis direction of the core roller and is substantially aligned with the center of the rotation center axis for contact with the power supply member. A ring-shaped concave conical surface that fits into and contacts the convex conical surface of the power receiving member for contacting the power receiving member, and the center of the ring-shaped concave conical surface of the power supply member is the convex shape of the power receiving member. 2. The heating roller device according to claim 1, wherein the heating roller device is substantially aligned with the center of the conical surface and is in contact with the convex conical surface. The heating roller device according to claim 4, wherein the ring-shaped concave conical surface of the power supply member is divided into two or more at predetermined center angle intervals.

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