JP2005321622A - Fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve uniform temperature distribution in an axial direction of a fixing roller without raising manufacturing cost. <P>SOLUTION: The fixing apparatus 1 is provided with the fixing roller 2, an induction heating coil 3 installed fixed inside the fixing roller 2, a space 4 between the fixing roller 2 and the induction heating coil 3 and a cooling fan to cool the induction heating coil 3 by having a cooling medium flow inside the space 4. In the fixing apparatus 1, the space 4 is partitioned by a partitioning member 5, the cooling fan is constituted by the first and the second cooling fans 6 and 7 making the cooling medium flow inside the first and the second spaces 4a and 4b, partitioned by the partitioning member 5, and the direction of making the cooling medium flow through the first and the second spaces 4a and 4b, partitioned by the partitioning member 5, is to be in the reverse direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device provided in an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to a mechanism for equalizing a temperature distribution of a fixing roller disposed in the fixing device.

  Image forming apparatuses such as copying machines, printers, and facsimiles are provided with an induction heating type fixing device that fixes toner onto transfer paper. Specifically, this fixing device has a cylindrical fixing roller in which an induction heating coil is disposed, and conducts Joule heat generated by the induction heating coil to the fixing roller, and passes through the fixing roller. The transfer paper is heated. Here, in the conventional fixing device, since the induction heating coil may generate excessive heat, a cooling fan is installed at the end of the fixing roller, and the fan is rotated to generate air in the fixing roller. It is made to distribute | circulate and the induction heating coil is cooled (for example, refer patent document 1).

In particular, in the fixing device of Patent Document 1, fans (coil cooling fans 3 and 4) for cooling the induction heating coil (induction coil 2) are installed at both ends of the fixing roller (heating roller body 1), respectively. Each time a certain amount of time has passed, the rotation direction of each fan is reversed to switch the air flow direction inside the fixing roller, and the temperature distribution in the axial direction of the fixing roller is made uniform (paragraph number 0007). , 0008).
JP 2002-72764 A

However, in the fixing device of Patent Document 1, the air flow direction is biased in one direction at any time zone only by switching the air flow direction at a constant time interval, and the temperature difference between the ends of the fixing roller is different. As a result, the temperature distribution in the axial direction of the fixing roller becomes slightly non-uniform. Therefore, in order to correct the non-uniform temperature distribution accurately, the rotation direction of each fan may be frequently switched. However, this shortens the air circulation time and may reduce the cooling efficiency. Further, in the fixing device of Patent Document 1, a control circuit for controlling the rotation direction of each fan is required, which causes an increase in manufacturing cost.
An object of the present invention is to make the temperature distribution in the axial direction of the fixing roller uniform without increasing the manufacturing cost.

In order to solve the above problem, the invention according to claim 1
A fixing roller;
An induction heating coil fixedly disposed in the fixing roller;
A space between the fixing roller and the induction heating coil;
A cooling fan for cooling the induction heating coil by flowing a cooling medium through the space;
In a fixing device having
Partitioning the space with a partition member;
The cooling fan is composed of a plurality of cooling fans for flowing a cooling medium in each space section partitioned by the partition member,
A direction in which a cooling medium flows in each space portion partitioned by the partition member by the plurality of cooling fans is set in a reverse direction.

  In the first aspect of the present invention, the direction in which the cooling medium flows into the respective space portions partitioned by the partition member is set in the reverse direction. The temperature difference between the ends of the fixing roller disappears. Therefore, the axial temperature distribution in the fixing roller is made uniform. In the first aspect of the invention, by continuously rotating each cooling fan in a fixed direction, the cooling medium can be caused to flow in the opposite directions to the respective spaces partitioned by the partition member. A control circuit for controlling the rotation direction of the fan is unnecessary. As described above, in the first aspect of the invention, the temperature distribution in the axial direction of the fixing roller can be made uniform without increasing the manufacturing cost.

The best mode for carrying out the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a cross-sectional view of the fixing device 1, and FIG. 2 is a vertical cross-sectional view of the fixing device 1.

  A fixing device 1 according to the present invention is provided in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, and includes a fixing roller 2 for fixing toner onto a transfer sheet. In addition to the fixing roller 2, the fixing device 1 has a pressure roller (not shown) for pressing the transfer paper, and the pressure roller is adjacent to the fixing roller 2 in a pressurized state. .

  In the fixing device 1, the transfer paper passes between both the fixing roller 2 and the pressure roller. During the passage, the pressure roller is heated while the transfer roller heats the transfer paper. The transfer paper is pressurized toward the fixing roller 2, and the toner is fixed to the transfer paper by the cooperation of these two rollers.

  As shown in FIGS. 1 and 2, the fixing roller 2 has a cylindrical shape. An induction heating coil 3 that generates heat when an induced current flows is fixedly disposed inside the fixing roller 2. The induction heating coil 3 has a cylindrical shape shorter than the fixing roller 2, and the central axis of the fixing roller 2 and the central axis of the induction heating coil 3 substantially coincide with each other. The radius of the induction heating coil 3 is smaller than the radius of the fixing roller 2, and a space 4 is formed between the fixing roller 2 and the induction heating coil 3.

  A flat partition member 5 is disposed inside the fixing roller 2. The partition member 5 is longer than the fixing roller 2, and both end portions thereof protrude outside the fixing roller 2. The space 4 formed inside the fixing roller 2 is divided into approximately two equal parts by a partition member 5, and is divided into two spaces, a first space 4a and a second space 4b. ing.

  In the vicinity of the one end portion 2a of the fixing roller 2 and at a position facing the first space portion 4a, air as a cooling medium is supplied to the first space portion 4a to cool the induction heating coil 3. One cooling fan 6 is arranged. The first cooling fan 6 rotates only in the direction in which air is fed into the first space portion 4a from the left to the right in FIG.

  On the other hand, in the vicinity of the other end 2b of the fixing roller 2 and at a position facing the second space 4b, the induction heating coil 3 is cooled by flowing air as a cooling medium in the second space 4b. For this purpose, a second cooling fan 7 is provided. The second cooling fan 7 rotates only in the direction in which air is fed into the second space 4b from right to left in FIG.

  Note that the induction heating coil 3 having a larger radius than the fixing roller 2 may be applied and the induction heating coil 3 may be disposed so as to surround the outer periphery of the fixing roller 2.

Next, the operation / action of the fixing device 1 will be described.
When the fixing roller 2 and the pressure roller rotate in opposite directions and the transfer paper passes between the two rollers, an induction current flows through the induction heating coil 3 to generate Joule heat, and the Joule heat is fixed. The fixing roller 2 is heated by being conducted to the roller 2. However, since the induction heating coil 3 and the partition member 5 are fixedly arranged in the fixing device 1, the induction heating coil 3 and the partition member 5 do not rotate along with the rotation of the fixing roller 2.

  In this state, the first and second cooling fans 6 and 7 are simultaneously rotated in a predetermined direction. When the first cooling fan 6 rotates, air flows through the first space 4a from the left to the right in FIG. 1, and the air serves as a cooling medium to cool the induction heating coil 3. On the other hand, when the second cooling fan 7 rotates, air flows from the right side to the left side in FIG. 1 in the second space 4b, and the air serves as a cooling medium to cool the induction heating coil 3. . That is, in the fixing device 1, the air flows in the opposite directions to the first and second space portions 4 a and 4 b to cool the induction heating coil 3.

  In the fixing device 1 described above, the first and second cooling fans 6 and 7 are simultaneously rotated in a predetermined direction, and air as a cooling medium flows in the fixing roller 2 in opposite directions to each other. The temperature difference between the one end 2a and the other end 2b is eliminated, and the temperature distribution in the axial direction of the fixing roller 2 can be made uniform. Further, in the fixing device 1, the first and second cooling fans 6 and 7 are continuously rotated in a certain direction, so that the air as the cooling medium is reversed to the first and second spaces 4a and 4b. The control circuit for controlling the rotation direction of each of the first and second cooling fans 6 and 7 is unnecessary. As described above, in the fixing device 1 according to the present embodiment, the temperature distribution in the axial direction of the fixing roller 2 can be made uniform without increasing the manufacturing cost.

  The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

  For example, the first cooling fan 6 is rotated from the right to the left in FIG. 1 in the direction of sucking out the air in the first space 4a, and the second cooling fan 7 is moved to the left in FIG. You may rotate in the direction which sucks out the air in the 2nd space part 4b toward right side.

  Further, as shown in FIG. 3, a third cooling fan 8 that sucks out the air in the first space 4a is provided in the vicinity of the other end 2b of the fixing roller 2 and facing the first space 4a. A fourth cooling fan 9 that sucks out the air in the second space 4b may be disposed near the one end 2a of the fixing roller 2 and at a position facing the second space 4b. .

  Further, a cooling pump is arranged in place of the first and second cooling fans 6 and 7 or the first, second, third and fourth cooling fans 6, 7, 8, and 9, and each cooling pump is operated. Thereby, it is good also as a structure which flows the liquid (for example, water) as a cooling medium to the mutually opposite direction with respect to 1st, 2nd space part 4a, 4b.

2 is a cross-sectional view of the fixing device. 2 is a drawing showing a longitudinal section of a fixing device. It is drawing (transverse sectional view) which shows the modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing device 2 Fixing roller 3 Induction heating coil 4 Space part 4a 1st space part 4b 2nd space part 5 Partition member 6 1st cooling fan 7 2nd cooling fan 8 3rd cooling fan 9 4th cooling fan

Claims (1)

A fixing roller;
An induction heating coil fixedly disposed in the fixing roller;
A space between the fixing roller and the induction heating coil;
A cooling fan for cooling the induction heating coil by flowing a cooling medium through the space;
In a fixing device having
Partitioning the space with a partition member;
The cooling fan is composed of a plurality of cooling fans for flowing a cooling medium in each space section partitioned by the partition member,
The fixing device according to claim 1, wherein a direction in which a cooling medium flows in each space portion partitioned by the partition member by the plurality of cooling fans is set in a reverse direction.

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