JP2006091116A - Induction heating apparatus for fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating apparatus for a fixing apparatus, capable of uniformly heating in an axial direction, regarding the heating apparatus introducing induction-heating, having a structure that heating coils are arranged separating in the axial direction. <P>SOLUTION: The apparatus is provided with a heat roller for heating a toner image, a plurality of induction coils arranged in the rotating axis direction of the heat roller so as to induction-heat the heat roller, a plurality of temperature sensors for detecting the surface temperature of the heat roller in accordance with the plurality of induction coils, and a heating driving means for driving the induction coils in accordance with the temperature detected by the plurality of temperature detecting sensors, and regarding the adjacent induction coils among the plurality of induction coils, the end parts overlap each other in the rotating direction of the heat roller. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device that fixes a toner image on a recording medium using an electrophotographic copying apparatus or the like, and more particularly to an induction heating device that heats toner or the like by induction heating.

  Heating is necessary to heat-fix the toner image, and for this purpose, a heating roller is used that uniformly heats the toner image in the axial direction by induction heating. In order to change the heating range according to the copying range, this heating roller often uses a structure in which, in addition to the heating coil provided at the center, another heating coil is used on both sides thereof (see, for example, Patent Document 1).

However, when a heating roller having such a structure is used, there is a problem that the temperature of the adjacent portion of the heating coil is lower than other portions, and it is difficult to apply heat uniformly in the axial direction. In particular, the problem of temperature unevenness becomes significant in a heating apparatus that performs fixing using a belt instead of a heating roller.
JP 2004-6353 A

  The conventional heating device having the above-described structure has a problem that it is difficult to heat uniformly, and the present invention has been made in view of the problems of such a conventional heating device. An object of the present invention is to provide an induction heating device for a fixing device capable of heating uniformly in the axial direction in a heating device using induction heating having a structure provided separately in the axial direction.

  According to the first aspect of the present invention, the heating rotator for heating the toner image, and the plurality of induction coils arranged in the direction of the rotation axis of the heating rotator for heating the heating rotator by induction heating, A plurality of temperature sensors for detecting the surface temperature of the heating rotator corresponding to the plurality of induction coils, and a heating drive for driving the induction coils corresponding to the temperatures detected by the plurality of temperature sensors. And the induction coil adjacent to the plurality of induction coils is provided at its end so as to overlap each other with respect to the rotation direction of the heating rotator. I will provide a.

  According to a second aspect of the present invention, in the induction heating device of the fixing device according to the first aspect, the end portions of the plurality of adjacent induction coils are summed in the outer circumferential direction at a portion where the adjacent induction coils are overlapped. The width of each of the induction coils is substantially the same as the width of each induction coil.

  According to claim 3 of the present invention, a heating rotator for heating the toner image, and a plurality of inductions arranged in the rotation axis direction inside the heating rotator for heating the heating rotator by induction heating. A coil, a core installed at an end portion of the induction coil adjacent to the plurality of induction coils, a plurality of temperature sensors for detecting a surface temperature of the heating rotating body corresponding to the plurality of induction coils, There is provided an induction heating device for a fixing device, comprising heating drive means for driving the induction coil corresponding to the temperatures detected by the plurality of temperature sensors.

  According to the present invention, it is possible to provide an induction heating device for a fixing device capable of heating uniformly in the axial direction in a heating device using induction heating having a structure in which heating coils are divided in the axial direction. effective.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are a front view and a side sectional view of a structural example of a heating apparatus according to an embodiment of the present invention. The induction heating device 10 includes a cylindrical heating roller 11 that is rotated by a rotation drive mechanism (not shown) and induction coils 12a, 12b, and 12c that are provided in close proximity to each other on the outer peripheral surface of the heating roller 11. It consists of.

  Each of the induction coils 12a, 12b, and 12c is wound in a spiral shape, and these coils are not aligned in the axial direction on the outer peripheral surface of the heating roller. As shown in FIG. Each end part of 12b is provided so that a part may overlap with induction coil 12a and induction coil 12c, Therefore, heating field 13a, 13b, 13c of the above-mentioned induction coil partially overlaps (overlaps).

  Then, by passing a current described later with reference to FIG. 2 to these induction coils 12a, 12b, and 12c, the heating roller 11 is rotated in the direction of the arrow 14 (rotation direction) by a rotation driving mechanism (not shown) and heated from the outer peripheral surface. For example, the toner image is melted and fixed to the recording medium at position 15 (not shown). Further, temperature sensors 18a, 18b, 18c for detecting the temperatures of the portions corresponding to the induction coils 12a, 12b, 12c provided on the outer periphery of the heating roller 10 are provided.

  FIG. 2 shows a configuration example of a heating drive circuit for passing a current through the induction coils 12a, 12b, and 12c. This heating drive circuit includes a high-frequency power source HFS connected to the low-frequency AC power source AS, an external signal source OSS that changes the output frequency of the high-frequency power source HFS, and an output high frequency of the high-frequency power source HFS as feed lines FC0, FC1, It comprises induction coil selectors F1, F2, and F3 that are selectively supplied to the induction coils 12a, 12b, and 12c via FC2 and FC3.

  Of the four power supply lines FC0, FC1, FC2, and FC3, the power supply line FC0 is commonly connected to each of the three induction coils 12a, 12b, and 12c, and a high-frequency power source via the induction coil selectors F1, F2, and F3 It is connected to the stable potential side of the output end of the HFS.

  The feeder line FC1 is connected to the other end of the induction coil 12b. Similarly, the feeder line FC2 is connected to the other end of the induction coil 12a, and the feeder line FC3 is connected to the other end of the induction coil 12c.

  The induction coil selectors F1, F2, and F3 are composed of bandpass filters, and their passbands are different from each other. For example, the pass band of the induction coil selection unit F1 is set to 1 MHz, the pass band of the induction coil selection unit F2 is set to 2 MHz, and the pass band of the induction coil selection unit F3 is set to 3 MHz.

  The induction coil selection unit F1 is interposed in series between the high-frequency power source HFS and the induction coil 12b. Similarly, the induction coil selection unit F2 is provided between the high-frequency power source HFS and the induction coil 12a and the induction coil. The selection unit F3 is interposed in series between the high frequency power supply HFS and the induction coil 12c. The temperature of each part of the heating roller 10 is detected by the temperature sensors 18a, 18b and 18c. When the recording medium comes into contact with the temperature, the temperature decreases, and each induction coil is driven to detect this and raise the temperature.

  A high-frequency output voltage of the high-frequency power supply HFS is selectively applied to the stationary induction coils 12b, 12a, and 12c via the induction coil selectors F1, F2, and F3. That is, when the external signal source OSS is operated and the frequency of the high-frequency output of the high-frequency power supply HFS is cyclically switched to 1 MHz and 2 MHz alternately at a frequency of 10 MHz, for example, the induction coil selector F1 passes 1 MHz. Therefore, when the high frequency power supply HFS outputs 1 MHz, the induction coil 12a is energized in a time division manner, and the corresponding heating region 13a is heated.

  Further, when the high frequency power supply HFS outputs 2 MHz, the induction coil 12b and the heating region 13b of the heating roller facing the induction coil 12b are heated. Therefore, since the heating region 13a and the heating region 13b are heated, the temperatures of the end portions 13a and 13b are evenly heated without lowering the temperature.

  On the other hand, when the external signal source OSS is operated and the frequency of the high frequency output of the high frequency power supply HFS is switched cyclically to 1 MHz, 2 MHz, and 3 MHz alternately at a low frequency of 10 MHz, for example, the induction coil selectors F1, F2, Since each of F3 passes high-frequency power having a passing frequency, the induction coils 12a, 12b, and 12c are alternately energized in a time division manner.

  As described above, the heating regions 13a and 13b formed by the induction coil 12a and the induction coil 12b and the heating regions 13b and 13c formed by the induction coil 12b and the induction coil 12c partially overlap with each other. Even in the portion, the temperature is uniformly heated without lowering.

  When the external signal source OSS is operated to switch the frequency of the high frequency output of the high frequency power supply HFS to, for example, 2 MHz, only the induction coil selector F2 passes high frequency power and only the induction coil 12b is energized. Therefore, in this case, only the heating region 13b corresponding to the induction coil 12b is heated. These heating regions are selected based on the temperatures detected by the temperature sensors 21a, 21b, and 21c.

  Thus, according to this embodiment of the present invention, since the end portions of the induction coils 12a, 12b, and 12c are provided so as to partially overlap each other, the temperature does not decrease at the end portions, According to the heating range corresponding to the fixing range, heating is performed uniformly in that range.

  In FIG. 3, the structure of the induction heating apparatus of other embodiment of this invention is shown. That is, in this case, the shape of the coil in the overlapping portion of the induction coils 32a, 32b, and 32c is gently changed. Numbers 30 to 33a, 33b, and 33c in FIG. 3 correspond to numbers 10 to 13a, 13b, and 13c in FIG. Corresponding to the induction coils 32a, 32b, and 32c provided on the outer periphery of the heating roller 30, temperature sensors 38a, 38b, and 38c that detect the temperatures of the portions are provided.

  When the induction coils 32a, 32b, and 32c have such shapes, the distances 36ab and 36bc corresponding to the induction heating time in the rotation direction of the heating roller are distances 36a corresponding to the induction heating times of the induction coils 32a, 32b, and 32c. 36b and 36c can be made substantially equal to each other, and there is an advantage that the degree of overlapping of the induction coils can be made relatively gradual as compared with the structure shown in FIG.

  In addition, although the said embodiment demonstrated the case where the induction coil was provided in the outer periphery of the heating roller, it is applicable similarly when the induction coil is provided in the inside of a heating roller. Also in the case of the heating apparatus having the structure shown in FIG. 3, temperature sensors as shown in FIG. 2 are provided corresponding to the respective heating regions.

  Still another embodiment of the present invention will be described next. FIG. 4 is a front view showing the structure of the heating device in this embodiment. In this figure, the heating device 40 includes a cylindrical heating roller 41 that is rotationally driven, induction coils 42a, 42b, and 42c disposed in the heating roller 41, and between the induction coil 42a and the induction coil 42b. And cores 43a and 43b provided between the induction coil 42b and the induction coil 42c. Corresponding to the induction coils 42a, 42b, 42c provided inside the heating roller 40, temperature sensors 48a, 48b, 48c for detecting the temperatures of the portions are provided.

  The induction coils 42a, 42b, and 42c can be driven in the same manner as described above by the circuit shown in FIG. That is, if necessary, the induction coils 42a, 42b, 42c can be driven individually, the induction coils 42a, 42b can be driven simultaneously, or the induction coils 42a, 42b, 42c can be driven simultaneously.

  In this embodiment, since the cores 43a and 43b are provided between the induction coil 42a and the induction coil 42b and between the induction coil 42b and the induction coil 42c, the induction magnetic flux can be made dense in this portion. Therefore, the corresponding part of the heating roller can be made slightly higher than the surroundings by induction heating, suppressing the temperature drop at the end of the induction coil and consequently making the heating roller uniform in the axial direction Is possible.

  In addition, although the drive circuit shown in FIG. 2 of embodiment of this invention uses a high frequency power supply, this invention can also drive-control an induction heating apparatus by low frequency. An example of this type of circuit is shown in FIG. The drive circuit includes a region selection unit 51 connected to a sensor (not shown), a power source 52a and a power source 52b connected to the region selection unit 51, induction coils 53a and 53b connected to these power sources, It comprises an induction heating device 54 that generates eddy currents by the induction coil and heats the toner image. The temperature selection is detected by the sensor, and the region selection unit 51 controls the heating range by selectively driving the power sources 52a and 52b. According to this embodiment, there is an advantage that a high frequency power supply is not required.

  By the way, in the description of the above embodiment, the example in which the rotating heating roller is heated by the induction coil has been described. However, what is rotated and heated may be a belt, and in the present invention, This is called a heating rotator.

FIG. 3 is a diagram illustrating a structure example of a heating device of a fixing device according to an embodiment of the present invention. The figure which shows the drive circuit example of the heating apparatus of the said one embodiment of this invention. The figure which shows the structural example of the heating apparatus of other embodiment of this invention. The figure which shows the structural example of the heating apparatus of other embodiment of this invention. The figure which shows the other example of a drive circuit of the heating apparatus used for this invention.

Explanation of symbols

10, 30, 40, 54 ... induction heating device,
11, 31, 41 ... heating roller,
12a, 12b, 12c, 32a, 32b, 32c, 42a, 42b, 42c, 53a, 53b ... induction coil,
18a, 18b, 18c, 38a, 38b, 38c, 48a, 48b, 48c ... temperature sensor,
51... Area selection unit,
52a, 52b ... power supply,
AS: Low frequency AC power supply,
HFS: high frequency power supply,
OSS ... external signal source,
F1, F2, F3 ... induction coil selector,
FC0, FC1, FC2, FC3 ... feeder lines.

Claims (3)

A heating rotator for heating the toner image;
A plurality of induction coils arranged in the direction of the rotation axis of the heating rotator to heat the heating rotator by induction heating;
A plurality of temperature sensors for detecting the surface temperature of the heating rotator corresponding to the plurality of induction coils;
Heating driving means for driving the induction coil corresponding to the temperature detected by the plurality of temperature sensors,
The induction heating device of the fixing device, wherein the induction coils adjacent to each other of the plurality of induction coils are provided so as to overlap each other with respect to the rotation direction of the heating rotator at the ends thereof.   The end portions of the plurality of adjacent induction coils are provided such that the total width in the outer circumferential direction is substantially the same as the width of each induction coil in a portion where the adjacent induction coils are overlapped. The induction heating device of the fixing device according to claim 1. A heating rotator for heating the toner image;
A plurality of induction coils disposed in the rotation axis direction inside the heating rotator to heat the heating rotator by induction heating;
A core installed at an end portion of an adjacent induction coil of the plurality of induction coils;
A plurality of temperature sensors for detecting the surface temperature of the heating rotator corresponding to the plurality of induction coils;
An induction heating device for a fixing device, comprising: a heating drive unit that drives the induction coil corresponding to the temperatures detected by the plurality of temperature sensors.

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