JP4450183B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an arrangement of a heating element of a fixing device including a power storage device that supplies electric power to the heating element, and to an image forming apparatus including the fixing device.

  In recent image forming apparatuses such as copying machines, printers, and facsimiles, a toner image is formed on a sheet such as transfer paper by an electrophotographic method, and then the toner is passed through a fixing device to heat the toner. A method of fixing an image is common.

  Further, in such a fixing device, a roller or an endless belt is heated by heat generated by a heating element supplied with electric power, and the toner is heated by bringing a fixing member such as the roller or the endless belt into contact with the sheet. ing. Here, power supply to the heating element is generally from a commercial AC power supply, but recently, a fixing device that supplies power to the heating element in combination with a power storage device has also been developed (see, for example, Patent Document 1). .)

  In other words, when the main unit is turned on from a state where the fixing device is not operating, commercial AC power is supplied to a plurality of heating elements in order to shorten the waiting time until the device can be used. Power was supplied from the power source and the power storage device to heat the fixing member, and it was possible to rapidly raise the temperature to the reload temperature.

Japanese Patent Laid-Open No. 2002-174988 (paragraphs 0035 to 0041, FIG. 21)

  However, even when the power supply to the heating element is controlled based on the temperature of the fixing member detected by the temperature detection means at the start-up of the apparatus, the fixing member may actually be heated above the set temperature. There was a safety problem.

  The present invention has been made in view of the above-described problems in the prior art, and in a power supply from a power storage device to a heating element, a safe fixing device in which a fixing member is heated within a set temperature or less and image formation An object is to provide an apparatus.

A fixing device according to the invention of claim 1 provided to solve the above-described problem has a plurality of heating elements that generate heat by supplying power therein, and a hollow-shaped fixing member that is heated by the radiant heat of the heating element. And a temperature detecting means for detecting the temperature of the fixing member, wherein the plurality of heating elements are shafts of the fixing member, wherein the toner on the sheet is heated by the fixing member and fixed to the sheet. A first heating element for a central region that generates heat in a central region in the direction, and an end that generates heat in an axial end region of the fixing member when electric power is supplied to the first heating element. A second heating element for the area, and a third heating element that generates heat in the central region and the end region in the axial direction of the fixing member, and the third heating element includes the third heating element, Even when power is supplied to the first heating element. The fixing device may not be provided, and the temperature detecting means includes a first temperature detecting means for detecting the temperature of the fixing member in the central area and a first temperature detecting means for detecting the temperature of the fixing member in the end area. Two temperature detection means, and in a cross section perpendicular to the axial direction of the fixing member, the first temperature detection means includes a temperature detection position of the first temperature detection means and the first heating element. Is disposed at a position that is less than the distance between the temperature detection position of the first temperature detection means and the second heating element, and from the first heating element to the first temperature detection means. The position where the third heat generating element does not shield the radiation heat to the temperature detecting position, and the distance between the temperature detecting position of the first temperature detecting means and the third heat generating element is the first temperature detecting means. Temperature detection position and the first heating element Distance is disposed below a position, and said second temperature detecting means, the distance between the temperature detection position and the second heating element of the second temperature detection means, said second temperature detecting means Is disposed at a position that is less than the distance between the temperature detection position and the first heating element, and radiant heat from the second heating element to the temperature detection position of the second temperature detection means is applied to the third heating element. The distance between the temperature detection position of the second temperature detection means and the third heat generation element is a position where the heat generation element is not shielded, and the temperature detection position of the second temperature detection means and the second heat generation element It is arrange | positioned in the position used as the distance below .
According to a second aspect of the present invention, there is provided a fixing device according to a second aspect of the present invention, wherein the first heating element, an external power supply for supplying power to the second heating element, and a charge / discharge are provided. A power source for supplying power to the third heat generating element, and when the amount of power stored in the power storage apparatus is equal to or less than a predetermined value, the first heat generating element is supplied from the external power source. Even when power is supplied to the third heating element, the third heat generator is not supplied with power from the power source.
According to a third aspect of the present invention, there is provided a fixing device according to a third aspect of the present invention, wherein, in the second aspect of the invention, when the amount of power stored in the power storage device is larger than the predetermined value, the first power supply is supplied from the external power source. The third heating element is supplied with electric power from the power source when electric power is supplied to the heating element.
According to a fourth aspect of the present invention, there is provided a fixing device according to the first to third aspects of the present invention, wherein the first heating element, the second heating element, and the third heating element are provided. Are alternately arranged in the hollow inner circumferential direction of the fixing member.

In order to solve the above problems, a plurality of heating elements for generating heat by electric power supply to the internal, and the fixing member of hollow heated by radiant heat of the heat generating member, a temperature detecting means for detecting a temperature of the fixing member A plurality of heating elements that are supplied with power only at the time of rising (heating element A). And at least one heating element (heating element B) that is supplied with electric power at the time of start-up and paper feeding, and among the heating elements B, the heating element closest to the temperature detection position of the temperature detection means The distance to the temperature detection position may be a fixing device that is equal to or less than the distance to the temperature detection position of the heating element closest to the temperature detection position in the heating element A (Configuration A). According to this invention, the distance to the temperature detection position of the heating element closest to the temperature detection position of the temperature detection means that is always supplied with power is closest to the temperature detection position of the temperature detection means, and the power supply is on / off controlled. The fixing member can be safely heated within the range of the set temperature or less by setting the heating element to be less than the distance to the temperature detection position.

In order to solve the above problems, a plurality of heating elements for generating heat by electric power supply to the internal, and the fixing member of hollow heated by radiant heat of the heat generating member, a temperature detecting means for detecting a temperature of the fixing member A plurality of heating elements that are supplied with power only at the time of rising (heating element A). And at least one heating element (heating element B) that is supplied with electric power at the time of rising and paper feeding, and the temperature detecting means is a surface position of the fixing member, and the heating element A is The difference in surface temperature of the fixing member between the case where only the heating element B generates heat in the attached state and the case where only the heating element B generates heat when the heating element A is removed is within a range where the surface temperature difference of the fixing member becomes substantially minimum. To be placed Optionally as a fixing device, wherein (configuration B). According to the present invention, when the temperature detecting means is the surface position of the fixing member and only the heating element B generates heat with the heating element A attached, and the heating element with the heating element A removed. By disposing the fixing member within a range where the difference in surface temperature between the fixing member and the case where only B generates heat is substantially minimized, the fixing member can be safely heated within the range of the set temperature or less.

According to the first to fourth aspects of the present invention, the third heating element or the heating element A having a state or mode in which the heat generation operation by the power supply from the power source is not performed even when the fixing device is in operation can be generated at any time. Since the radiant heat from the heating element or the heating element B to the temperature detection position of the fixing member is not shielded, the detection temperature of the fixing member by the temperature detection means can be matched with the temperature other than the temperature detection position. Can be safely heated within the range of the set temperature or lower.
The control for setting the fixing member to a predetermined temperature based on the temperature detected by the temperature detecting means is, for example, an on / off control for controlling power supply to the heating element by turning on / off the switch at the temperature of any fixing member, The relationship between the current temperature read by the temperature detection means with respect to the target temperature of the fixing member may be performed by PID control or the like that also reads how the temperature has changed in the past and feedback-controls the power supply amount.

In order to solve the above problems, a hollow fixing member having a plurality of heating elements that generate heat by power supply therein and heated by the radiant heat of the heating element, and a temperature at which the temperature of the fixing member is detected A fixing device that heats the toner on the sheet by the fixing member and fixes the toner on the sheet, and the heating element sets the fixing member to a predetermined temperature based on the temperature detected by the temperature detecting means. Controlled power is supplied, and at least one of the heating elements (heating element A) has a state or mode in which no heat generation operation is performed by power supply from the power source even when the fixing device is in operation, and the remaining heating elements ( The heating element B) can always generate heat by supplying power from a power source when the fixing device is in operation, and the temperature detecting means is located on the surface of the fixing member and only the heating element A generates heat. Between the position where the surface temperature difference of the fixing member and the second largest position with respect to the case where only the heating element B generates heat is arranged within a range not including those positions. A fixing device may be used. Thereby, the temperature detection means maximizes the surface temperature difference of the fixing member between the case where only the heating element A generates heat and the case where only the heating element B generates heat at the surface position of the fixing member. By being arranged between the position and the second largest position in a range that does not include those positions, the fixing member can be safely heated within a range below the set temperature.

According to the second aspect of the present invention , the fixing member can be heated more rapidly and safely than when the power source using the power storage device is the auxiliary power source and only the external power source is the power source.
In this case, using a direct current power source such as a capacitor or a lithium ion battery or a nickel hydrogen battery using the electric double layer capacity or pseudo capacitance which is one embodiment of a power storage device, for example, in the third heating element, the first and second heat generation An AC power source such as a commercial external power source may be used for the body .

In the inventions of the configurations A and B, it is preferable that the heating element A and the heating element B are alternately arranged in the hollow inner peripheral direction of the fixing member .

As a result, the fixing member is uniformly heated without temperature unevenness, and the fixing member can be heated more safely within the range of the set temperature or less. Note that the fixing member can be heated relatively uniformly even when no power is supplied to the heating element A.

According to a fifth aspect of the present invention, there is provided an image forming apparatus including the fixing device according to any one of the first to fourth aspects.

According to the invention of claim 5 , the third heating element or heating element A does not shield the radiant heat from the first and second heating elements or heating element B to the temperature detection position of the fixing member. It is possible to safely heat the toner up to the temperature required for fixing the toner within a range below the set temperature.

According to the first to fourth aspects of the present invention, the fixing member can be safely heated within a set temperature range.
According to the fifth aspect of the present invention, the fixing member can be safely heated up to a temperature required for toner fixing within a range below the set temperature.

Hereinafter, a configuration that is a premise of the present embodiment will be described with reference to the drawings.
FIG. 20 shows an example of a fixing device. In FIG. 20, a pressure roller 2 is pressed against a fixing roller 1 which is an embodiment of a fixing member with a constant nip pressure by a pressing means (not shown), and is fixed in the drawing by a driving mechanism (not shown). The roller 1 rotates in the clockwise direction, and the pressure roller 2 rotates in the counterclockwise direction. Further, the fixing roller 1 has heaters 91 and 92 which are one form of heat generating elements that generate heat when supplied with electric power, and the surface of the fixing roller 1 is heated to a temperature at which the toner can be fixed by the heating of the heaters 91 and 92. This is the reload temperature. The surface temperature of the fixing roller 1 is monitored by a temperature detection unit 3 such as a temperature detection unit that detects the temperature by contacting the surface of the fixing roller 1.

  When the image forming process is performed in the image forming apparatus, the sheet P carrying the toner T by the electrophotographic method is added to the fixing roller 1 when passing through the nip portion between the heated fixing roller 1 and the pressure roller 2. The toner T is fixed to the sheet P by being heated by the pressure roller 2. At this time, in order to fix the toner T to the sheet P, predetermined heat is required. For this reason, power supply to the heaters 91 and 92 is controlled so that the surface temperature of the fixing roller 1 becomes the reload temperature.

  FIG. 21 shows a circuit configuration example of the fixing device. In FIG. 21, a heater 91 generates heat by electric power supplied from an external power supply (commercial power supply) 87, and a heater 92 generates heat by electric power supplied from a capacitor 88 that is one mode of the power storage device. Further, the temperature of the fixing roller 1 detected by the temperature detecting means 3 is input as a detection signal to the CPU 83 via the input circuit 82, and the CPU 83 sets the surface temperature of the fixing roller 1 based on the detection signal from the temperature detecting means 3. Energization to the heater 91 is controlled via the driver 84 so that the temperature is reached, and energization to the heater 92 is controlled via the switch SW. The capacitor 88 is connected to the charging device 89 and can be charged by switching the switch 85.

  In the above configuration, when the fixing device 90 is started up from a state where the main power is turned on or the like, either of the heaters 91 and 92 is used in order to shorten the waiting time until the device can be used. Is also energized to heat the fixing roller 1, and the temperature is rapidly raised to the reload temperature. This eliminates the need for preheating power in the resting state and realizes efficient heating of the fixing roll 1.

  When the fixing device 90 is started up, the fixing roller 1 is heated based on the temperature detected by the temperature detecting means 3 while the fixing roller 1 is not rotated. That is, when the temperature of the fixing roller 1 detected by the temperature detecting unit 3 does not reach a predetermined temperature as the electric power is supplied from the external power source 87 to the heater 91, the switch SW is switched to the ON side. Thus, power is supplied from the capacitor 88 to the heater 92 (ON control). Further, when the temperature of the fixing roller 1 detected by the temperature detecting means 3 reaches the upper limit value of a predetermined temperature set in advance, the switch SW is switched to the OFF side, whereby the power from the capacitor 88 to the heater 92 is changed. Supply is shut off (off control). Alternatively, the temperature of the fixing roller 1 after a predetermined time is predicted from the temperature of the fixing roller 1 and its temperature rising gradient, and the capacitor 92 is heated from the capacitor 88 by the switch SW so as not to exceed the preset upper limit value of the predetermined temperature. The power supply to is cut off (off control). At the same time, the electric power from the external power source 87 is continuously supplied to the heater 91, but the amount of electric power is suppressed by the driver 84 to such an extent that the temperature of the fixing roller 1 can be maintained at the reload temperature. In this way, the power supply from the capacitor 88 to the heater 92 is on / off controlled, so that the power supply from the external power source 87 to the heater 91 is not on / off controlled, and the fixing roll is efficiently maintained while being always supplied. It is possible to prevent the temperature of the fixing roller 1 from being excessively raised while raising the temperature of 1.

  However, depending on the arrangement of the heating element, even if the power supply to the heating element is controlled based on the temperature of the fixing member detected by the temperature detecting unit as described above, the fixing member actually exceeds the set temperature. There was a problem of being heated. An example is shown in FIG.

  FIG. 22 shows a heater 93 in which the fixing roller 1 generates heat by receiving power supply from a capacitor, which is one embodiment of the power storage device, and heaters 94 and 95 that generate heat by receiving power supply from an external power source. It is sectional drawing which shows the structure heated by these three heat generating bodies. The fixing roller 1 has a hollow cylindrical shape, and the temperature detecting means 3 is disposed on the opposite side of the nip portion 4 across the center axis of the fixing roller 1 with the outer portion of the fixing roller 1 as a temperature detection position. Further, in the drawing, the heaters 93, 94, 95 are shown in a cross-sectional shape of, for example, a rod-shaped heater, and are uniformly arranged on the circumference separated from the inner surface of the cylinder by a predetermined distance with the central axis of the fixing roller 1 as the center. Has been. Further, the heater 93 is arranged directly above the temperature detecting means 3 in the upper part of the fixing roller 1 in the hollow, and the heaters 94 and 95 are arranged in the lower part of the fixing roller 1 in the hollow. Regarding the power supply, as described with reference to FIG. 21, the power to the heater 93 is supplied from the capacitor by on / off control, and the power to the heaters 94 and 95 is always supplied from an external power source.

In FIG. 22, when the fixing device is started up, the fixing roller 1 is heated based on the temperature detected by the temperature detecting unit 3 while the fixing roller 1 is stationary.
At this time, if the capacitor is charged and has sufficient capacity to supply power, the temperature of the fixing roller 1 does not reach the predetermined temperature set in advance. Along with the supply, power is supplied from the capacitor to the heater 93, and the temperature of the fixing roller 1 is rapidly increased. At this time, the fixing roller 1 is uniformly heated by the heaters 93, 94, and 95 in the circumferential direction of the roller. Therefore, the detected temperature of the fixing roller 1 by the temperature detecting means 3 and the temperature in the vicinity of the nip portion 4 substantially coincide as shown by the dotted line in FIG. 23, and when the temperature detecting means 3 detects the arrival at the reload temperature (T ₁ The reload temperature is also reached in the vicinity of the nip 4 (T _nip ), and after that time, the temperature detection position of the temperature detection means 3 and the vicinity of the nip 4 are almost consistent and maintained at the reload temperature. The power supply is controlled.

  On the other hand, in FIG. 22, when the capacitor is not sufficiently charged and there is no capacity, even if the circuit is assembled and controlled to be able to supply power from the capacitor to the heater 93, the capacitor is actually turned on. Thus, no electric power is supplied to the heater 93. Therefore, the fixing roller 1 is heated only by supplying power from the external power source to the heaters 94 and 95.

Heating of the fixing roller 1 is performed by receiving the radiant heat from each heater on the inner surface of the fixing roller 1. In the state where power is not supplied from the capacitor to the heater 93 in FIG. The periphery is a position where the radiant heat of the heaters 94, 95 is shielded by the heater 93, and the temperature in the vicinity of the nip portion 4 is always higher than the temperature at the temperature detection position of the temperature detection means 3. Therefore, the detected temperature of the fixing roller 1 by the temperature detecting means 3 and the temperature in the vicinity of the nip portion 4 do not coincide with each other as shown by the solid line in FIG. 23, and the detected temperature by the temperature detecting means 3 reaches the reload temperature ( T ₂ ), the reload temperature is reached in the vicinity of the nip portion 4 (T _nip ). Further, since the detection result of the temperature detection means 3 has not reached the reload temperature, the power supply is controlled so as to continuously raise the temperature of the fixing roller 1, and the vicinity of the nip portion 4 is still heated even if the reload temperature is exceeded. . This overheating is continued until the temperature detecting means 3 detects the arrival of the reload temperature (T ₁ ), and the temperature in the vicinity of the nip portion 4 may exceed the ignition temperature of the sheet.

  The case where the capacitor is insufficiently charged is specifically, for example, immediately after the fixing device is started up, if the main power supply is turned off immediately, the capacitor is not charged, and then the main power supply is turned on for fixing. This is the case when trying to start up the device.

  A first embodiment of a fixing device according to the present invention will be described below with reference to the drawings. In addition, embodiment shown below is an illustration and is not limited to this.

FIG. 1 is a cross-sectional view showing a configuration of a fixing device according to the present invention.
1 is in contact with the fixing roller 1 heated by three heaters 11 to 13, the pressure roller 2 that presses the fixing roller 1 with a constant nip pressure, and the surface temperature of the fixing roller 1. Temperature detecting means 3 for detecting.

The fixing roller 1 is usually a hollow cylindrical roller, but may be in the form of an endless belt. Further, the fixing device 10 is stationary when the fixing device 10 rises, and rotates in the clockwise direction in the drawing when the sheet is passed.
Here, the time of rising is when the main power of the apparatus is turned on or when the apparatus is returned from the standby state, and when the temperature of the fixing roller 1 needs to be raised.

  The pressure roller 2 is usually a cylindrical roller whose surface is made of an elastic member such as silicone rubber, but may be in the form of an endless belt. The pressing roller 2 is pressed against the fixing roller 1 by being pressed in the direction of the fixing roller 1 with a constant pressure by a pressing means (not shown). The pressure roller 2 is also stationary when the fixing device 10 rises, and rotates counterclockwise in the figure when the sheet is passed. The rotation of the fixing roller 1 and the pressure roller 2 is driven by a driving mechanism (not shown).

  The temperature detecting means 3 is arranged on the opposite side of the nip portion with the central axis of the fixing roller 1 as the temperature detection position on the outer side of the fixing roller 1. In addition, any thermometer that can detect the surface temperature of the fixing roller 1 may be a contact thermometer, a non-contact thermometer, a thermocouple, or the like.

The heaters 11 to 13 are bar heaters that are an embodiment of the heating element, such as halogen heaters, and the cross-sectional shape is shown in the figure.
The heater 11 generates heat when power is supplied when the amount of electricity stored in a capacitor, which is an aspect of the power storage device, is sufficient, and heats the fixing roller 1 by its radiant heat, while the amount of electricity stored in the capacitor reaches a predetermined level. If not, no power is supplied and no heat is generated.
The heaters 12 and 13 generate heat by being fed from an external power source that can be constantly fed, such as a commercial AC power source, and heat the fixing roller 1 by the radiant heat.
The capacitor is a direct current power source, and a capacitor module such as an electric double layer capacitor having a rated voltage of 2.5 V and a capacitance of about 300 to 1500 F connected in series and in parallel to a high voltage of 30 to 200 V is used. Is preferred.
In addition, the heaters 11 to 13 are all controlled to be turned on by on / off control or PID control.

The heaters 11 to 13 are evenly arranged on a circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center. The heater 11, the distance to the temperature detection position of the temperature detection means 3 and L _D, the heater 13 is close to the temperature detection position of the temperature detection means 3 than heater 12, and until the temperature detected position of the temperature detection means 3 and the distance are arranged so satisfied the relationship of the following expression when the L _a.

L _A ≦ L _D

Here, when the fixing device 10 rises, the fixing roller 1 is heated based on the detected temperature of the fixing roller 1 by the temperature detecting means 3 in a stationary state without rotating. That is, when the temperature of the fixing roller 1 detected by the temperature detecting means 3 does not reach a predetermined temperature as well as the power is supplied from the external power source to the heaters 12 and 13, the power is supplied from the capacitor to the heater 11. Is performed (ON control). Further, when the temperature of the fixing roller 1 detected by the temperature detecting means 3 reaches the upper limit value of a predetermined temperature set in advance, the power supply from the capacitor to the heater 11 is cut off by switching or the like (OFF) control). Alternatively, the temperature of the fixing roller 1 after a predetermined time is predicted from the temperature of the fixing roller 1 and its temperature rising gradient, and power is supplied from the capacitor to the heater 11 so as not to exceed a preset upper limit value of the predetermined temperature. Is shut off (off control). At the same time, power is continuously supplied from the external power source to the heaters 12 and 13, but the amount of power is suppressed to such an extent that the temperature of the fixing roller 1 can be maintained at the reload temperature.
In the fixing device 10, the method for fixing the toner formed on the sheet is the same as the conventional method.

  With the arrangement of the heaters 11 to 13 described above, even when the supply power is not stored in the capacitor as a power supply source to the heater 11 in heating the fixing roller 1 such as rising of the fixing device 10, the heater 11 Since the radiant heat from the heater 12 and / or the heater 13 to the temperature detection position of the temperature detection means 3 is not shielded, the temperature detected by the temperature detection means 3 of the fixing roller 1 and the temperature in the vicinity of the nip portion are substantially matched. Thus, the fixing roller 1 can be safely heated within a range below the set temperature.

  Variations of the first embodiment of the fixing device according to the present invention are shown in FIGS. In any case, only the arrangement of the heaters is different, and the other configuration and the power supply control method are the same as those in the case of FIG.

  In FIG. 2, the heater 21 generates heat when power is supplied from the capacitor by on / off control, and the heaters 22 and 23 generate heat when supplied from an external power source capable of always supplying power, both of which are fixed by radiant heat. The roller 1 is heated. The heaters 21 to 23 are evenly arranged on a circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as a center. Further, the heater 23 closest to the temperature detection position of the temperature detection means 3 and supplied with electric power from an external power source is closer to the temperature detection position of the temperature detection means 3 than the heater 21 whose power supply is on / off controlled. 3 is arranged so as to be close to the temperature detection position 3.

  In FIG. 3, the heater 31 generates heat when electric power is supplied from the capacitor by on / off control, and the heaters 32 and 33 generate heat when supplied from an external power source capable of always supplying power, both of which are fixed by radiant heat. The roller 1 is heated. The heaters 31 to 33 are evenly arranged on a circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center. In addition, the heater 33 (or the heater 32) supplied with power from the external power source closest to the temperature detection position of the temperature detection means 3 is closest to the temperature detection position of the temperature detection means 3 and the heater 31 whose power supply is on / off controlled. It arrange | positions so that it may become close to the temperature detection position of the temperature detection means 3. FIG.

  In the case of FIGS. 2 and 3, even when the supply power is not stored in the capacitor as a power supply source to the heater 21 or 31 during the heating of the fixing roller 1 such as rising of the fixing device, Since the radiant heat from the heater to the temperature detection position of the temperature detection means 3 is not shielded, the detection temperature of the fixing roller 1 by the temperature detection means 3 and the temperature in the vicinity of the nip portion can be substantially matched, and the fixing roller 1 can be safely heated within the range of the set temperature or lower.

Other variations of the first embodiment of the fixing device according to the present invention are shown in FIGS.
FIG. 4 is a perspective view showing the configuration of the fixing device. In FIG. 4, the three heaters 11 a to 13 a have different structures that emit light (heat generation) in the width direction (heater longitudinal direction) of the fixing roller 1, and have two temperature detection means 3 </ b> A and 3 </ b> B. The configuration other than the above and the power supply control method are the same as those in FIG.

In FIG. 4, a heater 11a is a full width heater that emits (heats) the full width in the width direction of the fixing roller 1 (heater longitudinal direction) when electric power is supplied from a capacitor by on / off control. ). The heater 12a is a central area heater that emits light (generates heat) in the central area in the width direction of the fixing roller 1 when power is supplied from an external power source, and has a rated power of 500 W (100 V), for example. The heater 13a is an end region heater that emits light (generates heat) in the end region in the width direction of the fixing roller 1 when power is supplied from an external power source, and has a rated power of 700 W (100 V), for example. FIG. 5 is a plan view showing a light emission (heat generation) region of each heater.
Further, the heaters 11a to 13a are equally arranged on a circumference that is separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as a center.

  Both heaters heat the fixing roller 1 by their radiant heat, but the fixing roller 1 is adjusted by adjusting the light emission conditions (heat generation conditions) in the width direction of the fixing rollers 1 of the heaters 12a and 13a as shown in FIG. It is possible to adjust the temperature distribution in the width direction.

  Further, since the temperature at the end of the fixing roller 1 is likely to drop particularly immediately after the start-up due to heat escape to the gears and side plates, the light emission distribution of the heater 11a used immediately after the start-up is fixed as shown in FIG. By slightly increasing the light emission intensity in the region corresponding to the end portion of the roller 1, the fixability immediately after rising can be made uniform in the width direction.

  The temperature detection means 3A is preferably arranged at the center A in the width direction of the fixing roller 1 so that the distance from the temperature detection position to the heater 11a is equal to or less than the distance from the temperature detection position to the heater 12a. An arrangement example of the temperature detecting means 3A is shown in FIG. 8A (a cross-sectional configuration at the central portion A in FIG. 4). Since the temperature detection means 3A is disposed at a position where the radiant heat of the heater 12a is not shielded by the heater 11a, the detected temperature of the temperature detection means 3A at the center in the width direction of the fixing roller 1 and the temperature near the nip portion Can be substantially matched.

  The temperature detection means 3B is preferably arranged at the end B in the width direction of the fixing roller 1 so that the distance from the temperature detection position to the heater 11a is equal to or less than the distance from the temperature detection position to the heater 13a. An arrangement example of the temperature detecting means 3B is shown in FIG. 8B (cross-sectional configuration at the end B in FIG. 4). Since the temperature detection means 3B is disposed at a position where the radiant heat of the heater 13a is not shielded by the heater 11a, the detected temperature of the temperature detection means 3B at the end in the width direction of the fixing roller 1 and the temperature in the vicinity of the nip portion Can be substantially matched.

  Next, a second embodiment of the fixing device according to the present invention will be described with reference to the drawings. In addition, embodiment shown below is an illustration and is not limited to this.

FIG. 9 is a cross-sectional view showing the configuration of the fixing device according to the present invention.
9 is in contact with the fixing roller 1 heated by the four heaters 41 to 44, the pressure roller 2 that presses the fixing roller 1 with a constant nip pressure, and the surface temperature of the fixing roller 1. Temperature detecting means 3 for detecting. The fixing roller 1, the pressure roller 2, and the temperature detecting means 3 have the same configuration as that of the fixing roller 1, the pressure roller 2 and the temperature detecting means 3 in FIG. The power supply has the same configuration as that shown in FIG.

The heaters 41 to 44 are rod-shaped heaters that are one mode of the heating element, and the cross-sectional shape is shown in the drawing.
The heaters 41 and 43 generate heat when electric power is supplied from a capacitor, which is an aspect of the power storage device, by on / off control, and heat the fixing roller 1 by the radiant heat.
The heaters 42 and 44 generate heat by being fed from an external power source that can be constantly fed, such as a commercial AC power source, and heat the fixing roller 1 by radiant heat.

  The heaters 41 to 44 are arranged uniformly on a circumference that is a predetermined distance away from the inner surface of the fixing roller with the central axis of the fixing roller 1 in the figure as a center, and a heater that is supplied with power from the capacitor on the circumference. The heaters supplied with electric power from an external power source are alternately arranged. In the drawing, the order of the heaters 41, 42, 43, 44 is shown. Further, the heater closest to the temperature detection position of the temperature detection means 3 and the distance to the temperature detection position of the heater 44 fed from the external power source is closest to the temperature detection position of the temperature detection means 3 and the power supply is on / off controlled. Each heater is arranged to be equal to or less than the distance to the temperature detection position 41.

Here, when the fixing device 40 starts up, the fixing roller 1 is heated based on the detected temperature of the fixing roller 1 by the temperature detecting means 3 in a stationary state without rotating. That is, when the temperature of the fixing roller 1 detected by the temperature detecting unit 3 does not reach a predetermined temperature as the power is supplied from the external power source to the heaters 42 and 44, the capacitor is supplied to the heaters 41 and 43. Electric power is supplied (ON control). Further, when the temperature of the fixing roller 1 detected by the temperature detecting means 3 reaches an upper limit value of a predetermined temperature set in advance, the power supply from the capacitor to the heaters 41 and 43 is cut off by switching or the like. (Off control). Alternatively, the temperature of the fixing roller 1 after a predetermined time is predicted from the temperature of the fixing roller 1 and its temperature rising gradient, and the capacitor is supplied to the heaters 41 and 43 so as not to exceed the preset upper limit value of the predetermined temperature. Power supply is cut off (off control). At the same time, power is continuously supplied from the external power source to the heaters 42 and 44, but the amount of power is suppressed to such an extent that the temperature of the fixing roller 1 can be maintained at the reload temperature.
In the fixing device 40, the method for fixing the toner formed on the sheet is the same as the conventional method.

  With the arrangement of the heaters 41 to 44 described above, even when the supply power is not stored in the capacitor as the power supply source to the heaters 41 and 43 in the heating of the fixing roller 1 such as the rise of the fixing device 40, the heater 41 does not shield the radiant heat from the heater 44 to the temperature detection position of the temperature detection means 3, so that the detection temperature of the fixing roller 1 by the temperature detection means 3 and the temperature in the vicinity of the nip portion can be substantially matched. It is possible to safely heat the fixing roller 1 within a range below the set temperature.

  Further, since the heater supplied with power from the capacitor and the heater supplied with power from the external power supply are alternately arranged, the fixing roller 1 is heated uniformly on the circumference without temperature unevenness. It becomes possible to heat 1 more safely within the range below the set temperature. In addition, the fixing roller 1 can be heated relatively uniformly even when the electric power stored in the capacitor is not sufficient and the electric power is not supplied to the heaters 41 and 43.

  Variations of the second embodiment of the fixing device according to the present invention are shown in FIGS. In any case, only the arrangement of the heaters is different, and the other configuration and the power supply control method are the same as those in FIG.

  In FIG. 10, heaters 51 and 53 generate heat when electric power is supplied from a capacitor by on / off control, and heaters 52 and 54 generate heat when supplied from an external power source capable of always supplying power, both of which emit radiant heat. Thus, the fixing roller 1 is heated. The heaters 51 to 54 are arranged in a state in which the heaters 41 to 44 in FIG. 9 are rotated 45 degrees counterclockwise about the central axis of the fixing roller 1 in the drawing. That is, the heaters 51 to 54 are uniformly arranged on a circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center, and power is supplied from the capacitor on the circumference. The heaters and heaters supplied with power from an external power source are alternately arranged. In the figure, the order of the heaters 51, 52, 53, 54 is shown. Also, the heater 54 that is closest to the temperature detection position of the temperature detection means 3 and is supplied with power from an external power source is closer to the temperature detection position of the temperature detection means 3 than the heater 51 (or heater 53) that is on / off controlled for power supply. It arrange | positions so that it may become close to the temperature detection position of the temperature detection means 3. FIG.

  In FIG. 11, heaters 61 and 62 generate heat when electric power is supplied from a capacitor by on / off control, and heaters 63 and 64 generate heat when supplied from an external power source capable of always supplying power, both of which emit radiant heat. Thus, the fixing roller 1 is heated. The arrangement of the heaters 61 to 64 is a configuration in which the power supply sources of the heaters 52 and 53 in FIG. That is, the heaters 61 to 64 are evenly arranged on the circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center, and power is supplied from the capacitor on the circumference. The heaters 61 and 62 are arranged side by side, and then the heaters 63 and 64 to which power is supplied from an external power source are arranged side by side. Further, the heater 64 supplied with power from the external power supply closest to the temperature detection position of the temperature detection means 3 is closer to the temperature detection position of the temperature detection means 3 than the heater 61 whose power supply is on / off controlled. It is arranged so as to be close to the temperature detection position.

  In FIG. 12, heaters 71 and 72 generate heat when electric power is supplied from a capacitor by on / off control, and heaters 73 and 74 generate heat when supplied from an external power source that can always supply power, both of which generate radiant heat. Thus, the fixing roller 1 is heated. The arrangement of the heaters 71 to 74 has a configuration in which the power supply sources of the heaters 41 and 44 in FIG. 9 are switched. That is, the heaters 71 to 74 are uniformly arranged on a circumference that is a predetermined distance away from the inner surface of the fixing roller with the central axis of the fixing roller 1 in the figure as the center, and power is supplied from the capacitor to the circumference. The heaters 71 and 72 are arranged side by side, and the heaters 73 and 74 to which power is supplied from an external power source are arranged side by side. Further, the heater closest to the temperature detection position of the temperature detection means 3 and the distance to the temperature detection position of the heater 73 supplied with power from the external power source is closest to the temperature detection position of the temperature detection means 3 and the power supply is on / off controlled. 72 is arranged to be equal to or less than the distance to the temperature detection position.

  In FIG. 13, the heaters 81 and 82 generate heat when electric power is supplied from the capacitors by on / off control, and the heaters 83 and 84 generate heat when supplied from an external power source capable of always supplying power, both of which emit radiant heat. Thus, the fixing roller 1 is heated. The arrangement of the heaters 81 to 84 is a configuration in which one heater that is supplied with electric power from the capacitor by on / off control is arranged at the position of the central axis of the fixing roller 1 in the arrangement of the three heaters in FIG. In other words, the heater 82 is arranged at the position of the central axis of the fixing roller 1, and the heaters 81, 83, 84 are on the circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center. Evenly arranged. Further, the heater closest to the temperature detection position of the temperature detection means 3 and the distance to the temperature detection position of the heater 84 fed from the external power source is closest to the temperature detection position of the temperature detection means 3 and the power supply is on / off controlled. It is arrange | positioned so that it may become below the distance to the temperature detection position of 81.

  In FIG. 14, the heaters a1 and a2 generate heat when electric power is supplied from the capacitors by on / off control, and the heaters a3 and a4 generate heat when supplied from an external power source capable of always supplying power, both of which emit radiant heat. Thus, the fixing roller 1 is heated. The arrangement of the heaters a1 to a4 is a configuration in which one heater that is supplied with electric power from the capacitor by on / off control is arranged at the center axis position of the fixing roller 1 in the arrangement of the three heaters in FIG. That is, the heater a2 is disposed at the position of the central axis of the fixing roller 1, and the heaters a1, a3, and a4 are on the circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center. Evenly arranged. Further, the heater a4 that is closest to the temperature detection position of the temperature detection means 3 and is fed from an external power source is closer to the temperature detection position of the temperature detection means 3 than the heater a2 whose power supply is on / off controlled. It is arranged so as to be close to the temperature detection position.

  In FIG. 15, heaters b1 and b3 generate heat when electric power is supplied from a capacitor by on / off control, and heaters b2 and b4 generate heat when supplied from an external power source that can always supply power, both of which radiate heat. Thus, the fixing roller 1 is heated. The arrangement of the heaters b1 to b4 is a configuration in which the power supply sources of the heaters 82 and 83 in FIG. That is, the heater b2 is arranged at the position of the central axis of the fixing roller 1, and the heaters b1, b3, b4 are on the circumference separated from the inner surface of the fixing roller by a predetermined distance with the central axis of the fixing roller 1 in the figure as the center. Evenly arranged. Further, the heater b4 that is closest to the temperature detection position of the temperature detection means 3 and that is supplied from an external power source is set closest to the temperature detection position of the temperature detection means 3 and the power supply is on / off controlled. It arrange | positions so that it may become below the distance to the temperature detection position of b3.

  In the case of FIGS. 10 to 15 as well, in the heating of the fixing roller 1 such as the rise of the fixing device, even when the supply power is not stored in the capacitor that is the power supply source to the heater, the heater that receives the power supply from the capacitor Since the radiant heat from the other heaters to the temperature detection position of the temperature detection means 3 is not shielded, the temperature detected by the temperature detection means 3 of the fixing roller 1 and the temperature near the nip portion can be made substantially coincident. The fixing roller 1 can be safely heated within a range below the set temperature.

  In the present invention, the temperature detection position of the fixing roller 1 by the temperature detection means 3 does not need to be a position facing the nip portion as shown in FIGS. 1 to 15, and is closest to the temperature detection position of the temperature detection means 3. A heater (for example, FIG. 1) whose power supply is controlled on and off closest to the temperature detection position of the temperature detection means 3 is the distance from the external power supply to the temperature detection position of the heater (for example, the heater 13 in FIG. 1). Any position on the fixing roller 1 may be used as long as the relationship between the heater 11) and the distance to the temperature detection position is maintained.

  Next, a third embodiment of the fixing device according to the present invention will be described with reference to the drawings. In addition, embodiment shown below is an illustration and is not limited to this.

The present invention is characterized in that the arrangement position of the temperature detecting means is determined based on the temperature distribution on the surface of the fixing roller. The conceptual diagram is shown in FIGS.
FIG. 16 is the same as the conventional fixing device shown in FIG. 22 except for the arrangement position of the temperature detection means 3 and its configuration and power supply control method. In the figure, the heater 94 is omitted to focus on the heaters 93 and 95. In addition, the dotted circles centered on the heaters 93 and 95 indicate the magnitude of the heater power of the respective heaters 93 and 95 by the size of the circles. In FIG. The case where the electric power is large is shown.

In FIG. 16, a solid line _Td1 indicates a temperature distribution on the surface of the fixing roller 1 when only the heater 93 is supplied with power from the capacitor and generates heat (case 1). A solid line T _d2 indicates the temperature distribution on the surface of the fixing roller 1 when only the heater 95 is supplied with power from the external power source and generates heat (case 2). In the figure, the further away from the fixing roller 1 the solid line T _d1 or the dotted line T _d2 , the higher the surface temperature at that position of the fixing roller 1, and the closer to the fixing roller 1, the lower the surface temperature. .

As a circumferential position of the surface of the fixing roller 1 in FIG. 16, the surface temperature distribution of the fixing roller 1 is shown in FIG. Curve _Td1 shows the surface temperature distribution in case 1 above, and curve _Td2 shows the temperature distribution in case 2 above. For reference, the surface temperature distribution when the heaters 93 and 95 are both fed and generate heat is shown as a curve _Td .

In FIG. 17, when the temperature difference between the curve T _d1 and the curve T _d2 is seen, the temperature difference becomes maximum at a position P ₁₂₀ of 120 ° from the position P ₀ immediately above the heater 93, and the temperature difference becomes second at the position P _0. It is getting bigger. Further, the temperature difference becomes zero at the position _{P b} which is between 0 ° to 120 ° is between positions _{P a} and 180 ° to 270 °.

In the present invention, the surface temperature distribution of the fixing roller 1 in each of the case 1 and the case 2 is measured, and the temperature detection means is located at a position on the fixing roller 1 where the temperature difference is small and within a predetermined range. It is characterized by arranging. For example, in FIG. 17, between a position _{P 120} and the position _{P 0} the second largest temperature difference is maximized, it is preferable to place within the range R without the position _{P 120} and the position _{P 0.} Thereby, it is possible to control the actual temperature near the nip portion to be equal to or lower than the ignition temperature of the sheet. The intermediate point between the position _{P 0} and the position _{P a} (position _{P 0} ') the temperature detected in the range R'between the intermediate point between the position _{P 120} and the position _{P a} (position _{P 120')} More preferably, means are arranged. Further, as shown in FIG. 16, it is more preferable that the position P _a , that is, the position where the temperature difference between the curve T _d1 and the curve T _d2 is substantially minimum is set as the arrangement position of the temperature detection means 3a. Thereby, it becomes possible to make the detected temperature of the temperature detecting means substantially coincide with the actual temperature in the vicinity of the nip portion.
Although there are two positions where the temperature difference is minimal (0), it is desirable to select the one having the higher surface temperature of the fixing roller 1.

FIG. 18 shows a variation of the third embodiment of the fixing device according to the present invention. The configuration of the apparatus is the same as that in FIG. 16, but the conditions for measuring the surface temperature distribution of the fixing roller 1 are different. That is, in FIG. 18, the dotted line T _d3 indicates the temperature distribution on the surface of the fixing roller 1 when only the heater 95 is supplied with power from the external power source and generates heat (case 3) with the heater 93 removed, and the solid line T _d4 indicates the temperature distribution on the surface of the fixing roller 1 when only the heater 95 is supplied with power from an external power source and generates heat (case 3) with the heater 93 attached.

In the present invention, the surface temperature of the fixing roller 1 in each of the case 3 and the case 4 is measured, and the temperature detecting means is arranged at a position where the temperature difference becomes substantially minimum. For example, in Figure 18, positions _{P d} of the temperature detecting means 3d corresponds to it.
Here, the arrangement position _Pc of the temperature detecting means 3c is a preferable position because the surface temperature difference between the fixing roller 1 between the case 3 and the case 4 becomes large due to the influence of the heater 93 shielding the radiant heat from the heater 95. is not.

  In the above-described embodiment, the case where the method of controlling the power supply from the capacitor to the heater has been described as an example of the on / off control. In addition to this, the temperature detection unit 3 for the target temperature of the fixing roller 1 is currently read. In the temperature relationship, PID control that feedback-controls the power supply amount by reading how the temperature has changed in the past may also be used.

Next, FIG. 19 shows a configuration example in which the fixing device 10 according to the first embodiment of the present invention is incorporated in an image forming apparatus.
In the image forming apparatus 100 of FIG. 19, the drum-shaped photosensitive member 101 as an image carrier, the charging unit 102 for uniformly charging the photosensitive member 101, and the laser beam L is exposed on the charged photosensitive member 101. The laser optical system 140 that forms an electrostatic latent image and the developing unit 107 that develops the electrostatic latent image on the photoconductor 101 into a toner image constitutes an electrophotographic mechanism. In addition, the toner image on the photosensitive member 101 is transferred to the sheet P supplied from the paper feeding cassette 110 by the transfer unit 106, and the sheet P on which the toner image is formed is conveyed to the fixing device 10 and pressed against the fixing roll 1. The toner is fixed to the sheet P by being heated and pressed by the roll 2.

In the image forming apparatus 100, when the main power is turned on, each part of the image forming apparatus 100 is activated, and at the same time, the fixing device 10 is also started up to start supplying power to the heaters 11 to 13 of the fixing device 10. Heating of the roller 1 is started. Here, the temperature detection of the fixing roller 1 and the control of the power supply shown in the first embodiment of the present invention are performed, and safe heating of the fixing roller 1 is realized within a range below the set temperature.
In the image forming apparatus 100, any one of the fixing devices shown in FIGS. 2 to 18 may be incorporated in place of the fixing device 10.

1 is a cross-sectional view illustrating a first embodiment of a fixing device according to the present invention. FIG. 6 is a cross-sectional view showing Variation 1 of the first embodiment of the fixing device according to the present invention. FIG. 6 is a cross-sectional view showing variation 2 of the first embodiment of the fixing device according to the present invention. FIG. 9 is a perspective view showing Variation 3 of the first embodiment of the fixing device according to the present invention. It is sectional drawing which shows the light emission range of each heater in FIG. FIG. 5 is a diagram illustrating a light emission distribution example (1) in the fixing roller width direction of each heater in FIG. 4. FIG. 5 is a diagram illustrating a light emission distribution example (2) in the fixing roller width direction of each heater in FIG. 4. It is sectional drawing which shows the arrangement position of the temperature detection means in FIG. FIG. 4 is a cross-sectional view illustrating a second embodiment of a fixing device according to the present invention. FIG. 9 is a cross-sectional view showing Variation 1 of the second embodiment of the fixing device according to the present invention. FIG. 10 is a cross-sectional view showing Variation 2 of the second embodiment of the fixing device according to the present invention. FIG. 9 is a cross-sectional view showing variation 3 of the second embodiment of the fixing device according to the present invention. FIG. 9 is a cross-sectional view showing a variation 4 of the second embodiment of the fixing device according to the present invention. It is sectional drawing which shows the variation 5 of 2nd Embodiment of the fixing device which concerns on this invention. It is sectional drawing which shows the variation 6 of 2nd Embodiment of the fixing device which concerns on this invention. FIG. 6 is a cross-sectional view illustrating a third embodiment of a fixing device according to the present invention. FIG. 10 is a diagram illustrating a surface temperature distribution in the circumferential direction of the fixing roller in the third embodiment of the fixing device according to the present invention. FIG. 10 is a cross-sectional view showing a variation of the third embodiment of the fixing device according to the present invention. 1 is a cross-sectional view illustrating a configuration example of an image forming apparatus according to the present invention. FIG. 10 is a cross-sectional view illustrating a configuration example of a conventional fixing device. FIG. 10 is a diagram illustrating a circuit configuration example of a conventional fixing device. FIG. 3 is a cross-sectional view illustrating a configuration example of a fixing device in the case of three heaters. It is a figure which shows the relationship between the detection temperature of a temperature detection means, and the temperature of the nip part vicinity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3, 3A, 3B, 3a, 3b, 3c, 3d Temperature detection means 4 Nip part 11-13, 11a-13a, 21-23, 31-33, 41-44, 51-54, 61 to 64, 71 to 74, 81 to 84, 91 to 95, a1 to a4, b1 to b4 heater 10, 20, 30, 40, 50, 60, 70, 80, 90, a, b fixing device 82 input circuit 83 CPU
84 Driver 85, SW switch 86 Thermostat 87 External power supply 88 Capacitor 89 Charging device 100 Image forming apparatus 101 Photoconductor 102 Charging means 103 Cleaning means 105 Developing sleeve 106 Transfer means 107 Developing section 110 Paper feed cassette 111 Middle plate 112 Arm 113 Paper feed Roller 114 Separation pad 115 Registration roller pair 120 Paper discharge roller pair 121 Paper discharge port 122 Paper discharge tray 125 Paper discharge auxiliary tray 130 Operation panel 131 Exterior part 132 Paper feed tray 133 Pin 134 Case 135 Power supply circuit 136 Print board 137 Controller board 140 Laser optical system T Toner P Sheet

Claims (5)

A plurality of heating elements that generate heat by supplying power therein, a hollow fixing member that is heated by the radiant heat of the heating element, and temperature detection means that detects the temperature of the fixing member, and on the sheet In a fixing device in which toner is heated and fixed on the sheet by the fixing member,
The plurality of heating elements include a first heating element for a central region in which an axial central region of the fixing member generates heat,
A second heating element for an end region where electric power is supplied when power is supplied to the first heating element, and an end region in the axial direction of the fixing member generates heat;
A third heating element that generates heat in the central region and the end region in the axial direction of the fixing member;
The third heating element is a fixing device that may not be supplied with power even when power is supplied to the first heating element,
The temperature detection means includes first temperature detection means for detecting the temperature of the fixing member in the central region, and second temperature detection means for detecting the temperature of the fixing member in the end region,
In a cross section perpendicular to the axial direction of the fixing member,
The first temperature detection means has a distance between the temperature detection position of the first temperature detection means and the first heating element such that the temperature detection position of the first temperature detection means and the second heating element. And a position where the third heat generating element does not shield radiant heat from the first heat generating element to the temperature detection position of the first temperature detecting means . The distance between the temperature detection position of the first temperature detection means and the third heating element is arranged at a position that is equal to or less than the distance between the temperature detection position of the first temperature detection means and the first heating element ,
And,
The second temperature detection means is configured such that the distance between the temperature detection position of the second temperature detection means and the second heating element is equal to the temperature detection position of the second temperature detection means and the first heating element. And a position where the third heat generating element does not shield radiant heat from the second heat generating element to the temperature detection position of the second temperature detecting means . The distance between the temperature detection position of the second temperature detection means and the third heating element is set at a position where the distance between the temperature detection position of the second temperature detection means and the second heating element is less than or equal to the distance. A fixing device. An external power source for supplying power to the first heating element and the second heating element;
A power source having a chargeable / dischargeable power storage device and supplying power to the third heating element,
When the power storage amount of the power storage device is equal to or less than a predetermined value, the third heating element is supplied from the power source even when power is supplied from the external power source to the first heating element. The fixing device according to claim 1, wherein power is not supplied.   When the amount of power stored in the power storage device is greater than the predetermined value, power is supplied from the power source to the third heating element when power is supplied from the external power source to the first heating element. The fixing device according to claim 2, wherein the fixing device is used.   The first heating element, the second heating element, and the third heating element are alternately arranged in a hollow inner circumferential direction of the fixing member. The fixing device according to claim 1.   An image forming apparatus comprising the fixing device according to claim 1.

Images