JP3497444B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus equipped with an induction heating type fixing device in which a coil is arranged inside a cylindrical heat roller made of a metal conductor.

[0002]

2. Description of the Related Art As a fixing device mounted on an image forming apparatus such as a copying machine, a facsimile, a printer, a fixing roller for thermally melting toner on the transfer sheet, and a transfer sheet sandwiched by being pressed against the fixing roller. Most commonly, it is composed of a pressure roller and a pressure roller. Here, as the fixing roller, conventionally, a heating element such as a halogen lamp is disposed inside the roller, and the surface of the roller is heated by radiant heat from the heating element. However, in such a fixing roller,
It takes a relatively long time for the roller surface to reach the proper temperature,
Further, since there are some problems such as large energy loss, an induction heating type (hereinafter referred to as IH type) fixing roller has been proposed as a solution to these problems. This IH fixing roller has a structure in which, for example, a coil wound spirally in the axial direction is arranged inside a heat roller made of a metal conductor, and a high-frequency current is passed through the coil to generate it. An induced eddy current is generated in the heat roller by the high-frequency magnetic field, and the heat roller itself causes Joule heat generation by the skin resistance of the heat roller itself. With such a configuration, it is possible to raise the temperature of the heat roller in a shorter time than indirect heating using a halogen lamp, etc., and it is possible to reduce energy loss due to heat generation and light leakage of parts other than the heat roller. is there.

[0003]

In the fixing roller of the IH type as described above, the temperature of the coil disposed inside the heat roller is conventionally increased by the heat generation of the coil itself or the radiant heat from the heat roller. There was a problem that it would end up. If the coil becomes hot, the coating of the coil wire (Litz wire) may melt and cause dielectric breakdown. As a result, the inductance value of the coil (L
(Value) may change, and the high-frequency power supply may be damaged significantly. The present invention has been made in view of the above circumstances, and an object thereof is to provide a fixing device that can effectively prevent overheating of a coil.

[0004]

In order to achieve the above object, the present invention is a state in which a coil is wound around a substantially cylindrical bobbin inside a cylindrical heat roller made of a metal conductor.
In an image forming apparatus equipped with an induction heating type fixing device, the bobbin around which the coil is wound is
Substantially cylindrical with a gap along the inner surface of the bobbin
Is configured to include a ferrite core
It is configured as an image forming apparatus characterized by that. With such a configuration, the cooling space passes through the gap.
Since the air circulates , the contact area between the coil and the air can be increased, the cooling efficiency of the coil can be increased, and the overheating of the coil can be effectively prevented. Further , since the bobbin is composed of a ferrite core, it is possible to effectively cool the ferrite core while improving the heat generation efficiency of the heat roller .

Further, if a blower means for generating an air flow is further provided inside the heat roller, the air can be forcedly passed through the air hole of the bobbin into the gap between the coils. It is possible to further improve the cooling efficiency of the coil. Here, as the air blowing means, if fins are attached to at least the inner surface side of the end portion of the heat roller, it is not necessary to separately provide a fan or the like, so that the cost can be further reduced. In addition, the fan and the fin at the end of the heat roller are used together, for example, a fan blows air into the coil, and the air passing through the air holes of the bobbin and the gap between the coil wires is exhausted to the outside of the heat roller by the fin. With this configuration, it is possible to further improve the cooling efficiency of the coil.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are examples of embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is the background of the present invention.
4 is a schematic diagram showing the schematic configuration of the bobbin 10 of the fixing roller Z1, FIG. 2 is a schematic diagram showing the overall configuration of the fixing roller Z1, FIG. 3 is a diagram showing the mounting state of the fins 2 at the end of the heat roller 1, FIG. FIG. 3 is a schematic view showing a fixing roller using the ferrite core 13 according to the embodiment of the present invention as a bobbin.

As shown in FIG. 2, an IH type fixing roller Z1 mounted in an image forming apparatus as a background of the present invention is as shown in FIG.
A coil 11 wound in a spiral around the axis of the heat roller 1 is arranged inside a cylindrical heat roller 1 formed of a metal conductor such as iron or nickel. The coil 11 is a bobbin 10 formed in a cylindrical shape.
On the other hand, the coil wire is wound so as to have a gap between the coil wires. Further, as shown in FIG. 1, the bobbin 10 is formed with air holes 10a which communicate with the inside and outside of the cylinder evenly over the entire surface.

Further, in the vicinity of both ends of the coil 11,
Fans 12 that blow air toward the inside of the coils 11 are attached. Further, the heat roller 1
Fins 2 as shown in FIG. 3 are attached to the inner surfaces of both ends 1a, 1a. The fins 2 are attached in a state in which they are twisted slightly in the circumferential direction with respect to the axial direction of the heat roller 1 so as to generate an air flow in the axial direction of the heat roller 1 as the heat roller 1 rotates. There is. The fins 2 are twisted in opposite directions at both ends of the heat roller 1. Therefore, when the heat roller 1 is rotated, the fins 2 attached to both ends of the heat roller 1 act in a direction to exhaust the air in the heat roller 1, respectively.

With the configuration as described above, in the fixing roller Z1 mounted in the image forming apparatus according to the present embodiment, as shown in FIG. 2, the cooling forcedly sent into the coil 11 by the fan 12 is performed. The wind passes through the air holes 10a of the bobbin 10 and, further, while passing through the gap between the coil wires, draws heat from the coil wires and flows in the normal direction of the coil 11, and is attached to both ends of the heat roller 1. The fins 2 smoothly exhaust the air toward the outside of the heat roller 1. Therefore, it is possible to effectively cool the coil 11 and prevent problems due to its overheating.

[0010] In the embodiments above Symbol embodiment, the fan 12, and the heat roller 1 two fins 2 provided at both ends of it with blowing means, either coil 1 even with only one
It is possible to create a flow of wind such as through a gap of 1 . Further, since the bobbin 10 is formed with the air holes 10a, the heat radiation effect from the coil 11 is higher than that of the conventional one. Therefore, even if the air blowing means such as the fan 12 or the fin 2 is not necessarily provided, And high cooling effect can be expected .

In the present invention, as shown in FIG. 4 in order to increase the heating efficiency of the heat roller 1, arranged in a cylindrical shape with a gap to each other rod-shaped ferrite core 13, configured thereto to wind the coil 11 directly I am doing . That is, the bobbin 10 is formed by the ferrite core 13 . This
As a result, not only the coil 11 but also the ferrite core is connected.
Even if it is, it can be cooled effectively. Of course, Figure 1
As shown in FIG. 4, inside the bobbin 10 as shown in FIG.
The ferrite core 13 may be arranged,
A plurality of fins 2 as shown in FIG.
It may be provided at one end or both ends. Furthermore, FIG.
Install the fan 12 as shown
It can also be installed at one end to improve cooling efficiency.
is there.

[0012]

As described above, according to the present invention, the coil is substantially circular inside the cylindrical heat roller made of a metal conductor.
In an image forming apparatus equipped with an induction heating type fixing device arranged in a state of being wound around a cylindrical bobbin, the bobbin around which the coil is wound is an inner surface of the bobbin.
It is arranged in a substantially cylindrical shape with a gap along
Since it is configured as an image forming apparatus characterized by including a ferrite core, the contact area between the coil and the air can be made large, and the cooling efficiency of the coil can be increased and the coil can be overheated. It is possible to prevent it. Here, since the bobbin is composed of the ferrite core, it is possible to effectively cool the ferrite core at the same time while increasing the heat generation efficiency of the heat roller. Of course, Ru possible der placing the ferrite core in the interior of the bobbin.

Further, if a blower means for generating a flow of air is further provided inside the heat roller, it becomes possible to force air to pass through the air gap of the bobbin into the gap of the coil. It is possible to further improve the cooling efficiency of the coil. Here, as the air blowing means, if fins are attached to at least the inner surface side of the end portion of the heat roller, it is not necessary to separately provide a fan or the like, so that the cost can be further reduced. In addition, the fan and the fin at the end of the heat roller are used together, for example, a fan blows air into the coil, and the air passing through the air holes of the bobbin and the gap between the coil wires is exhausted to the outside of the heat roller by the fin. With this configuration, it is possible to further improve the cooling efficiency of the coil.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a bobbin 10 of a fixing roller Z1 mounted in an image forming apparatus which is a background of the present invention .

FIG. 2 is a schematic diagram showing an overall configuration of the fixing roller Z1.

FIG. 3 is a view showing a mounting state of fins 2 at an end of heat roller 1.

FIG. 4 is a schematic diagram showing an example in which a ferrite core 13 according to an embodiment of the present invention is used as a bobbin.

[Explanation of symbols]

1 ... Heat roller 2 ... Fins (an example of blowing means) 10 ... Bobbin 10a ... Air hole 11 ... Coil 12 ... Fan (an example of a blower) 13 ... Ferrite core

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20 H05B 6/00-6/44

Claims (3)

(57) [Claims] 1. A coil wound around a substantially cylindrical bobbin inside a cylindrical heat roller made of a metal conductor.
In an image forming apparatus equipped with an induction heating type fixing device arranged in a stationary state, a bobbin around which the coil is wound extends along an inner surface of the bobbin.
This is a lens that is arranged in a substantially cylindrical shape with a gap in between.
An image forming apparatus comprising a light core . 2. The image forming apparatus according to claim 1, further comprising an air blowing unit for generating an air flow inside the heat roller. 3. The image forming apparatus according to claim 1, wherein the blower unit includes a fin attached to at least an inner surface side of the end portion of the heat roller.