JP4043113B2 - Fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device having an induction coil inside a fixing roller.
[0002]
[Prior art]
Usually, the main part of this type of fixing device has a fixing roller that heats a sheet on which unfixed toner adheres, and a pressure roller that presses and conveys the sheet. A halogen lamp or the like is provided inside the fixing roller as a heater, and the inside of the fixing roller is heated by the heater to raise the fixing roller to a predetermined temperature.
[0003]
However, such a heating system has a long rise time until the fixing roller is heated to a predetermined temperature, and the heater itself has a large loss. For this reason, when environmental issues such as global warming are being brought up as in the present, such things will become undesirable, and this can be eliminated and the efficiency will be improved. Good ones with short rise times are required.
[0004]
In order to meet these requirements, an induction heating type fixing device has been proposed, which can heat the fixing roller in a short time by eddy current due to electromagnetic induction, shortening the rise time and improving the efficiency. It can be adapted to environmental problems. Then, an induction coil is used as a member for induction heating of the fixing roller, and the induction coil is replaced with a halogen lamp or the like inside the fixing roller so as not to obstruct the conveyance of the paper.
[0005]
[Problems to be solved by the invention]
A typical example of this is shown in FIG. 8, wherein 31 is a support member having a bobbin 34 to which an induction coil 33 for induction heating is attached on the outer periphery thereof. The hollow shaft portion 38 of the fixing roller 31 is rotatably supported by a support shaft 36 protruding from both side surfaces of the bobbin 34 via a bearing 37. A lead wire 39 having one end connected to the induction coil 33 is disposed in the hollow hole 41 provided in the support shaft 36, and the lead wire 39 is led out of the support shaft 36 and connected to a power source. Yes.
[0006]
In such a case, the induction coil 33 heats the fixing roller 31 to about 160 to 200 ° C. necessary for image fixing. However, since the induction coil 33 is located inside the fixing roller 31, The induction coil 33 that does not need to be heated is heated by conduction heat or radiant heat of the fixing roller 31 and rises to a temperature exceeding the temperature rise regulation value in the safety standard. Further, the induction coil 33 is burned out. There is a problem such as.
[0007]
[Problems to be solved by the invention]
Therefore, as a means for solving such a problem, there is a conventional method in which the bobbin 34 is hollowed and cooled by passing air through the hollow portion. However, the induction coil 33 is not directly hit by the wind and is sufficiently cooled. Can not do it. For this reason, in order to prevent the induction coil 33 from being burned by being heated by the fixing roller 31, the maximum input power must be limited, the rise time cannot be shortened, and fixing cannot be performed for a long time. There is a problem that there is. There is also a method of flowing cooling air to the induction coil 33 side. In this case, the cooling air can directly cool the induction coil 33. However, at the same time, the cooling air also hits the fixing roller 31 to heat it. The fixing roller 31 that does not become necessary is cooled on the contrary, and the input has to be further increased, and there is a problem that it is not possible to realize efficiency improvement or energy saving by induction heating.
[0008]
Accordingly, an object of the present invention is to solve the problems of the conventional fixing device as described above, and the induction coil is heated by conduction heat or radiant heat from the fixing roller, so that the temperature exceeds the temperature rise regulation value in safety standards. It is an object of the present invention to provide a fixing device that does not rise or burn out, and can quickly heat the fixing roller.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in the fixing device, in the fixing device, the fixing roller , the bobbin disposed inside the fixing roller , and the bobbin are packaged. comprising an induction coil, a non-conductive tubular heat insulator that is spaced a predetermined distance outside the induction coil, and a axial fan arranged axially one side of the cylindrical heat insulator, wherein The bobbin and the cylindrical heat insulating material are fixed to the side plate of the apparatus main body with a bracket, and the fixing roller is rotatably supported on the side plate via a bearing, and is substantially straight between the bobbin and the cylindrical heat insulating material. The flow path is configured so that the blade portion of the axial fan is opposed to the flow path, and the air flow generated by the axial fan flows around the outer periphery of the induction coil in the flow path. Configured to cool the induction coil forcibly It is characterized in.
[0010]
The invention described in claim 2 is characterized in that in the invention described in claim 1, a duct is provided for guiding the air flow generated by the axial fan to the flow path.
[0011]
According to a third aspect of the present invention, in the invention according to the first or second aspect , the pitch of the central portion of the induction coil is rough.
[0012]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the cylindrical heat insulating material is a hollow structure having a hollow portion in which air is sealed inside the cylindrical peripheral wall. It is characterized by that.
[0013]
The invention according to claim 5 is the invention according to any one of claims 1 to 4 , wherein the cylindrical heat insulating material is a foamed member obtained by foaming a resin .
[0014]
The invention according to claim 6 is the invention according to claim 5 , wherein the foamed member comprises a single bubble portion.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first embodiment of the present invention, wherein 1 is a fixing roller, and 2 is a pressure roller that is pressed against and rotated by the fixing roller 1. The fixing roller 1 comprises a core bar made of a magnetic material such as stainless steel or iron and provided with a release layer made of a fluororesin, and a driving gear 5 is attached to one end thereof. Further, it is rotatably supported on the side plate 20 of the fixing device via a bearing 21. And the bobbin 3 is arrange | positioned in the inside.
[0016]
An induction coil 4 is mounted on the bobbin 3, and a straight non-conductive cylindrical heat insulating material 6 is provided in a space between the fixing roller 1 and the induction coil 4. And the cooling means 19 which has the axial flow fan 9 which forcibly air-cools the induction coil 4 by flowing a wind in the space 7 between the cylindrical heat insulator 6 and the induction coil 4 is provided at one end of the cylindrical heat insulator 6. Yes. The bobbin 3 and the cylindrical heat insulating material 6 are supported by a bracket (not shown) provided on the side plate of the fixing device, and a high frequency current is passed through the induction coil 4 by a lead wire (not shown).
[0017]
In such a case, when image fixing is performed, a high-frequency current is passed through the induction coil 4 to heat the fixing roller 1 in the same manner as the conventional one, and both rollers 1 and 2 are in the direction indicated by the arrows in FIG. When the recording sheet S is rotated, the recording sheet S carrying the toner image T is conveyed to the nips, and the toner image T is fixed by pressurization and heating by both rollers 1 and 2.
[0018]
When fixing work is performed in this way, the cooling air is circulated in the space 7 between the induction coil 4 and the tubular heat insulating material 6 by the air cooling means 19 so that the induction coil 4 is forcibly cooled by air. It has become. The cylindrical heat insulating material 6 blocks the heat from the fixing roller 1 to the induction coil 4 to prevent the temperature rise, and the fixing roller 1 heated by electromagnetic induction by the cylindrical heat insulating material 6 is blocked from the cooling air. Thus, there is no adverse effect on the heating of the toner image T of the recording sheet S without cooling.
[0019]
The second embodiment shown in FIG. 3 corresponds to an embodiment of the invention described in claim 2 and is different from the first embodiment only in that a hollow portion 8 is formed in the tubular heat insulating material 6. There is no other difference. In such a case, the heat to the induction coil 4 from the fixing roller 1 is more effectively blocked by the heat insulating function of the air sealed in the hollow portion 8 to prevent the temperature rise, and the fixing roller. 1 is not effectively cooled by cooling air from the cooling air, and the heating of the toner image T on the recording sheet S is not adversely affected.
[0020]
The third embodiment shown in FIG. 4 corresponds to an embodiment of the invention described in claims 3 and 4, and the cylindrical heat insulating material 6 is manufactured from a foamed member obtained by foaming a resin so as to reduce the weight. In addition, the foamed portion of the foamed member is a single foamed portion, which is different from the second embodiment in that it can supply a stable tubular heat insulating material 6 having a large bending strength and a small amount of bending.
[0021]
The fourth embodiment shown in FIG. 5 corresponds to an embodiment of the invention described in claim 5, and the cooling means 19 is installed on both sides of the fixing roller 1, and one axial fan 9 of the cooling means 19 is The other axial flow fan 9 ′ exhausts the supplied air, and the ducts 11 and 12 guide the cooling air from the cooling means 19 between the induction coil 4 and the tubular heat insulating material 6. Is provided.
[0022]
In the first place, the space 7 between the induction coil 4 and the cylindrical heat insulating material 6 is several mm. In order to cool the induction coil 4 effectively by circulating cooling air in such a space 7, An axial fan that can obtain a large air volume is adopted. This axial fan has a small air volume at the center and a maximum air volume at the blades due to its structure. For this reason, in this embodiment, the air is squeezed and sent using the long ducts 11 and 12 having an opening substantially the same shape as the opening of the tubular heat insulating material 6, thereby reducing the amount of air blown. Therefore, the two axial fans 9, 9 'are provided, and the wind of the blade portion having the largest air volume is pumped and discharged into the space 7 between the induction coil 4 and the tubular heat insulating material 6. If necessary, either the axial fan 9 or 9 'need not be provided.
[0023]
The fifth embodiment shown in FIG. 6 corresponds to an embodiment of the invention described in claim 6, and the induction coil 4 is different from the first embodiment only in that the pitch of the central portion 13 is rough. There is no other difference. Since the induction coil 4 is the place where the temperature of the central portion 13 is most likely to rise, by increasing the pitch here, the ventilation resistance is increased and the turbulent flow of the cooling air is easily generated. The coil 4 is effectively cooled.
[0024]
In the sixth embodiment shown in FIG. 7, the cooling means 19 ′ uses a heat insulating coolant, and supplies this coolant between the induction coil 4 and the tubular heat insulating material 6, so that the induction coil 4 is different from the fourth embodiment in that it performs cooling and heat insulation, and water, silicon oil, or the like is used as the liquid refrigerant. In this cooling means 19 ′, a pump 15 is installed on one opening side of the space 7, and a refrigerant container 16 is installed outside the other opening side, respectively. The vessel 16 and the opening of the space 7 are connected by connecting pipes 17 and 18 that supply and discharge liquid refrigerant to the opening of the space 7.
[0025]
And when fixing work is performed by such a thing, a liquid refrigerant is distribute | circulated to the space 7 between the cylindrical heat insulating material 6 and the induction coil 4 by the pump 15, and the induction coil 4 is forcedly cooled, Similarly to the other embodiments, heat from the fixing roller 1 to the induction coil 4 is blocked to prevent the temperature from rising, and the fixing roller 1 is blocked from the liquid refrigerant by the cylindrical heat insulating material 6 and cooled. Therefore, there is no adverse effect on the heating of the toner image T of the recording sheet S.
[0026]
【The invention's effect】
The invention has been described above, the invention according to claim 1, in the fixing device, a fixing roller, a bobbin disposed inside the fixing roller, an induction coil which is externally mounted on the bobbin, the comprising a non-conductive tubular heat insulator that is spaced a predetermined distance outside the induction coil, and a axial fan arranged axially one side of the tubular insulation the bobbin and the tubular thermal insulation The material is fixed to the side plate of the apparatus body with a bracket, and the fixing roller is rotatably supported on the side plate via a bearing, and a substantially straight flow path is formed between the bobbin and the cylindrical heat insulating material. The axial flow fan is installed so that the blade portion of the axial flow fan faces the flow path, and the air flow generated by the axial flow fan flows around the induction coil in the flow path to forcibly cool the induction coil. since it is configured to, the airflow What can cool the Blocked and induction coil to heat to the induction coil from the fixing roller, the electromagnetic induction effect can be obtained favorably according to the induction coil to prevent the temperature rise of the induction coil, air flow fixing roller Therefore, the fixing roller is not cooled and the fixing roller is not cooled, and it is possible to maintain a good fixing property without affecting the heating of the toner image on the recording sheet. In particular, since the substantially straight flow path is configured, the air flow is not diminished due to the flow path, and high distribution efficiency is obtained. In addition, since the air flow generated by the blade portion having the largest air volume in the axial flow fan is circulated through the flow path, a high air volume can be obtained efficiently. For this reason, it is possible to easily and surely secure a sufficient air flow rate for cooling the induction coil itself while shielding heat from the fixing roller . On the other hand, the driving force of the axial fan required to secure this air flow rate can be reduced.
[0027]
Since the invention according to claim 2 includes a duct for guiding the air flow generated by the axial fan to the flow path, the use of a large-sized air-cooling fan having a large diameter and air volume regardless of the shape of the apparatus. Thus, there is an effect that the induction coil can be efficiently cooled.
[0028]
In the third aspect of the present invention, since the pitch of the induction coil is rough in the induction coil, it is easy to generate an appropriate turbulent flow in the air flow near the central part of the induction coil that is most likely to rise in temperature. The heat exchange between the air and the induction coil can be activated by turbulent flow to effectively cool the induction coil, and the magnetic flux density in the central part is low and the eddy current is reduced. The effect is that the temperature distribution of the fixing roller can be made uniform by weakening.
[0029]
In the invention according to claim 4 , since the cylindrical heat insulating material is a hollow structure having a hollow portion in which air is sealed inside the cylindrical peripheral wall , an air layer is formed inside the cylinder, and this is stopped. The air layer cuts off heat from the outside, more effectively cuts off heat from the fixing roller to the induction coil to prevent the temperature from rising, and is interposed between the induction coil and the fixing roller . Since the number of air layers as the insulating layer is increased by newly adding the stopped air layer, it is possible to prevent discharge from the induction coil to the fixing roller .
[0030]
In the invention according to claim 5 , since the cylindrical heat insulating material is a foamed member obtained by foaming a resin, there is an effect that the weight can be reduced.
[0031]
In the invention according to claim 6 , since the foamed member is composed of a single bubble portion, a large number of sealed chambers are formed inside the cylinder, and it becomes a stable cylindrical heat insulating material with a high bending strength and a small amount of bending. There is an effect that heat from the fixing roller to the induction coil can be blocked more effectively, and temperature rise of the induction coil can be further prevented.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view taken along line 2-2 of the above.
FIG. 3 is a longitudinal sectional view of a second embodiment of the present invention.
FIG. 4 is a longitudinal sectional view of a third embodiment of the present invention.
FIG. 5 is a longitudinal sectional view of a fourth embodiment of the present invention.
FIG. 6 is a longitudinal sectional view of a fifth embodiment of the present invention.
FIG. 7 is a longitudinal sectional view of a sixth embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of a conventional induction heating roller of the same type as that of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Bobbin 4 Induction coil 5 Drive gear 6 Cylindrical heat insulating material 7 Space 8 Hollow part 9 Axial fan 9 'Axial fan
11 Supply duct 12 Discharge duct
13 Center 15 Pump
16 Refrigerant container 17 Connecting pipe
18 Connecting pipe 19 Cooling means
19 ′ Cooling means

Claims (6)

In the fixing device,
A fixing roller , a bobbin disposed inside the fixing roller , an induction coil sheathed on the bobbin, a non-conductive cylindrical heat insulating material disposed at a predetermined interval outside the induction coil, and a axial fan arranged axially one side of the cylindrical heat insulator,
The bobbin and the cylindrical heat insulating material are fixed to a side plate of the apparatus main body with a bracket, and the fixing roller is rotatably supported on the side plate via a bearing, and is substantially straight between the bobbin and the cylindrical heat insulating material. flow channel constitutes a and blade portion of the axial fan in the flow channel is disposed opposite an air flow to the axial flow fan is generated, it flows through the outer periphery of the induction coil in the flow channel A fixing device configured to forcibly cool the induction coil .   The fixing device according to claim 1, further comprising a duct that guides an air flow generated by the axial fan to the flow path. The induction coil fixing device according to claim 1 or 2, characterized in that the pitch of the central portion is roughened. The cylindrical heat insulating material, a fixing device according to any one of 3 claims 1, wherein the air inside the tubular wall is a hollow structure having a hollow portion which is sealed. The tubular insulation fixing device according to any one of claims 1 to 4, characterized in that a foamed member obtained by foaming the resin. The fixing device according to claim 5 , wherein the foam member includes a single bubble portion.

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