JP5186838B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction machine having at least two functions thereof, which includes the fixing device.

In recent years, in the image forming apparatus described above, there is an increasing demand for reducing the supply of power to the fixing device as much as possible in a standby state from the viewpoint of energy saving. However, in a device in which a mode in which the power supply to the fixing device during standby is eliminated or greatly reduced is set, there is a problem that it takes time until the fixing device starts up at the time of printing, which is inconvenient for the user. In view of this, a fixing device having a heating means for heating by electromagnetic induction that can be quickly started up has been proposed. Such a fixing device that performs electromagnetic induction heating uses a eddy current generated by electromagnetic induction to directly heat a heated part having heat generation by electromagnetic induction. Therefore, it is said that the heat conversion efficiency is high, and the surface of the fixing roller can be quickly raised to the fixing temperature with less electric power.

JP 2006-259718 A Japanese Patent No. 3882800

  By the way, in a fixing device that performs electromagnetic induction heating, an electromagnetic induction heating means is provided on the outside of the roller or the belt, and in the configuration that locally heats about a half roller portion of the belt wound around the roller, a thermopile or the like The belt temperature is detected by the non-contact sensor.

  In Patent Document 1, a non-contact sensor is positioned with respect to a rotating shaft of a heated rotating body, so that the sensor position is maintained with high accuracy and temperature detection is highly refined. In the first place, since the rotating body is heated by electromagnetic induction heating means and the temperature after passing through the nip is detected, the temperature of the part heated by electromagnetic induction heating is not detected. Since the non-contact sensor detects the temperature rise with a delay from the rise, there is a problem that the responsiveness deteriorates.

  Patent Document 2 discloses that a temperature sensor is disposed between coils, and a fixing device that reduces the above-described responsiveness problem is disclosed. However, in such a configuration, the temperature sensor may come into contact with the fixing member due to defective setting of the fixing device or the like, and may be damaged. Patent Document 2 also describes that a temperature sensor is provided outside the ferrite core and the temperature is detected through a through hole formed in the ferrite core. However, when a through hole is formed in the ferrite core, an air current for cooling the coil flows into the fixing device, the heated portion is locally cooled, and an abnormal image due to cold offset may occur.

  An object of the present invention is to provide a fixing device and an image forming apparatus that can prevent the occurrence of damage and abnormal images while suppressing the deterioration of the responsiveness of the temperature sensor.

In order to achieve the above object, the present invention provides a fixing device including an electromagnetic induction heating unit including a coil and a coil guide that supports the coil, and a heating member heated by the electromagnetic induction heating unit. A mounting hole is provided in the coil guide of the induction heating means, a temperature detection means for detecting the temperature of the heating member is fitted into the hole, the hole is closed, and the temperature detection means is provided in the hole of the cylindrical portion. A fixing device is proposed in which a gap generated when fitted is sealed with another member .

In addition, this invention is effective when the distance from the said coil guide to the said temperature detection part is larger than the distance from the said heating member to the said coil guide .

Furthermore, the present invention is effective when the heating member is an endless belt including a heat generating layer that generates heat by the electromagnetic induction heating means.
Furthermore, the present invention is effective when the heating member is a roller having a heat generating layer that generates heat by the electromagnetic induction heating means.

Furthermore, the present invention is effective when a heat generating member is wound around both of the pair of rollers around which the endless belt is wound.
In order to achieve the above object, the present invention proposes an image forming apparatus using the fixing device according to any one of claims 1 to 6.

  According to the present invention, since the thermopile as the temperature detecting means is provided in the coil guide of the electromagnetic induction heating means, the responsiveness is improved, and the temperature detection without causing a delay in temperature detection can be performed. Further, the integration prevents the air flow for cooling the coil from flowing through the temperature detection hole of the thermopile, and prevents the occurrence of abnormal images that occur when the heated member is locally cooled. Furthermore, the installation space is reduced by integrating the thermopile and the coil guide.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The basic configuration of the image forming apparatus to which the present invention is applied will be clarified. FIG. 1 is a schematic sectional view showing an example of an image forming apparatus. The image forming apparatus shown here has an image forming apparatus main body 1. Inside the image forming apparatus main body 1, a drum-shaped photoconductor 2, which is an example of an image carrier that is rotatably supported, is rotationally driven in the clockwise direction in FIG. The surface is charged to a predetermined polarity. The optical writing unit 4 emits laser light L that is light-modulated according to image information, exposes the surface of the photosensitive member charged with the laser light L, and thereby forms an electrostatic latent image on the surface of the photosensitive member. Is done. The electrostatic latent image is visualized as a toner image by powdered toner when passing through the developing device 5. This toner image is transferred to a recording medium P fed between the photoconductor 2 and the transfer device 6 as will be described later by the transfer device 6 facing the photoconductor 2. The surface of the photoconductor after the toner image is transferred is cleaned by a cleaning device 7.

  For example, a recording medium P made of transfer paper or a resin sheet is stacked on a paper feeding device 8 provided at the lower part of the image forming apparatus main body 1, and the uppermost recording medium P is fed in the direction of the arrow by a paper feeding roller 9. The toner image is fed and conveyed to the transfer section via the registration roller 10, and the toner image formed on the photosensitive member 4 is transferred to one surface thereof. The recording medium P to which the toner image has been transferred passes through the fixing device 20, and at that time, the unfixed toner image is fixed to the recording medium P by the action of heat and pressure. Then, the recording medium P that has been fixed is stocked on the paper discharge tray 11.

Next, the configuration / operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail with reference to FIG.
FIG. 2 is a configuration diagram showing the fixing device 20.

  In FIG. 2, the fixing device 20 in this embodiment includes a fixing belt 21 as a fixing member and a pressure roller 30 as a pressure member. The fixing belt 21 includes a heating roller 22 and a fixing roller whose axis is parallel to the roller. 23. In the vicinity of the heating roller 22, an electromagnetic induction heating means having a coil 25 and a coil guide 26, which will be described in detail later, is arranged. The heating roller 22 generates heat by this electromagnetic induction heating means, and the fixing belt 21 is heated to a predetermined temperature. The Reference numeral 24 denotes a tension roller that applies tension to the fixing belt 21, and reference numeral 32 denotes a temperature sensor that detects the temperature in the vicinity of the fixing nip portion.

  The pressure roller 30 is brought into pressure contact with the fixing roller 23 via the fixing belt 21, and a fixing nip portion is formed between the fixing belt 21 and the pressure roller 30 in a portion wound around the fixing roller 23. The unfixed toner image is fixed to the recording medium P by the action of heat and pressure by passing through the fixing nip portion so that the toner image side of the recording medium P carrying the unfixed toner image is in contact with the fixing belt 21.

  In the fixing device 20 configured as described above, a thermopile 31 as temperature detecting means for detecting the surface temperature of the fixing belt 21 is provided integrally with the coil guide 26. Specifically, as shown in FIGS. 3 and 4, a cylindrical portion 27 is formed in the coil guide 26 according to the outer peripheral shape of the thermopile 31, and the thermopile 31 is fitted and integrated into a through hole of the cylindrical portion 27. Yes. Therefore, it is possible to detect the temperature at substantially the center of the heating roller 22 that is a heated portion.

In the fixing device 20 in which the thermopile 31 is installed by fitting into the through hole of the coil guide 26 in this way, wiring to the thermopile 31 can be performed from the outside of the coil guide 26. The through hole is closed by the thermopile 31 itself, and the gap is further closed by another member such as a heat-resistant cover, so that the coil cooling airflow does not reach the fixing belt 21 and is locally cooled. The generation of abnormal images due to can be prevented .

  FIG. 5 shows a fixing device 20 according to another embodiment of the present invention, in which the fixing belt 21 is configured as a heating member that is heated by electromagnetic induction heating means. The fixing belt 21 is wound around a support roller 28 and a fixing roller 23 whose axis is parallel to the support roller.

  In the fixing device 20, the fixing belt 21 is provided with a heating layer (not shown) that generates heat by electromagnetic induction heating means, and the fixing belt 21 is directly heated. In this fixing device, the thermopile 31 is provided integrally with the coil guide 26 as in the above embodiment.

  FIG. 6 shows a fixing device 20 according to still another embodiment of the present invention. The fixing member of this example is a fixing roller 23 that directly contacts a pressure roller 30 having parallel axes so as to form a fixing nip portion. The fixing roller 23 is also configured as a heating member that is heated by electromagnetic induction heating means.

  In such a fixing device 20, the fixing roller 23 is provided with a heating layer (not shown) that generates heat by electromagnetic induction heating means, and the fixing roller 23 is directly heated, and the thermopile 31 is coiled as in the above embodiment. The guide 26 is integrally provided.

  Although the preferred embodiments of the present invention have been described above, the present invention can be applied to a fixing device that can employ an electromagnetic induction heating method. For example, a device in which a pressure member pressed against a fixing belt is also configured by a belt, The present invention can be applied to a device in which the pressure roller is in pressure contact with a non-rotating pad via a fixing belt.

1 is a schematic cross-sectional view illustrating an image forming apparatus including a fixing device according to the present invention. 1 is an enlarged configuration diagram showing an embodiment of a fixing device according to the present invention. It is a perspective view which shows an example of the coil guide of an electromagnetic induction heating means. It is explanatory drawing which shows the structure of an electromagnetic induction heating means. It is an expanded block diagram which shows other embodiment of the fixing device which concerns on this invention. FIG. 10 is an enlarged configuration diagram showing still another embodiment of the fixing device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Fixing device 21 Fixing belt 22 Heating roller 24 Tension roller 26 Coil guide 27 Cylinder part 30 Pressure roller 31 Thermopile

Claims (6)

In a fixing device having an electromagnetic induction heating unit including a coil and a coil guide that supports the coil, and a heating member heated by the electromagnetic induction heating unit,
A tube portion in which a mounting hole is formed in the coil guide of the electromagnetic induction heating means is provided, and a temperature detecting means for detecting the temperature of the heating member is fitted into the hole of the tube portion to close the hole , A fixing device characterized in that a gap generated when the temperature detecting means is fitted in the hole of the cylindrical portion is closed with another member .   The fixing device according to claim 1, wherein a distance from the coil guide to the temperature detection unit is larger than a distance from the heating member to the coil guide.   The fixing device according to claim 1, wherein the heating member is an endless belt including a heat generating layer that generates heat by the electromagnetic induction heating unit.   The fixing device according to claim 1, wherein the heating member is a roller having a heat generating layer that generates heat by the electromagnetic induction heating unit. 4. The fixing device according to claim 3 , wherein a heat generating member is wound around both of a pair of rollers around which the endless belt is wound. An image forming apparatus characterized in that with a fixing device according to any one of claims 1 to 5.

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