JP4782546B2 - Auxiliary power supply apparatus for image forming apparatus and fixing apparatus - Google Patents

Description

  The present invention forms a toner image on an image carrier, transfers the toner image to a long recording medium longer than a standard size, and records the toner image transferred to the long recording medium with a fixing device. The present invention relates to an image forming apparatus for fixing to a medium and an auxiliary power supply device for the fixing device.

  According to the above-described image forming apparatus configured as an electronic copying machine, a printer, a facsimile machine, or a multifunction machine thereof, an image can be formed on a long recording medium having a length of, for example, 10 m to 15 m. is there. A fixing device used in such an image forming apparatus has a fixing member, a pressure member pressed against the fixing member, a temperature detecting means for detecting the temperature of the fixing member, and a heating means for heating the fixing member. A long recording medium carrying a toner image is passed through the nip portion between the fixing member and the pressure member, and heat and pressure are applied to the toner of the toner image on the long recording medium during the passage. The toner image is fixed on a long recording medium. When a long recording medium is passed between the fixing member and the pressure member of such a fixing device, the heat of the fixing member continues to be taken away by the long recording medium for a long time. While the long recording medium passes through the fixing member, the temperature of the fixing member becomes lower than the temperature suitable for fixing the toner image, or the amount of heat supplied by the fixing member to the toner on the long recording medium is fixed to the toner image. Therefore, there is a possibility that a toner image fixing defect may occur. Therefore, when a fixing member having a large heat capacity is used and the long recording medium passes between the fixing member and the pressure member, the temperature of the fixing member may be lower than the temperature suitable for fixing the toner image. It is necessary to prevent the amount of heat supplied to the toner from the fixing member from being less than the amount suitable for fixing the toner image. However, when such a large-capacity fixing member is used, it is inevitable that the start-up time until the fixing member rises to a temperature suitable for fixing the toner image becomes long during the start-up operation of the fixing device.

  The general configuration of the fixing device used in the image forming apparatus is described in, for example, Patent Documents 1 to 5.

JP 2002-184554 A JP 2005-39873 A JP 2005-32558 A JP 2005-18049 A Japanese Patent Application Laid-Open No. 11-65362

  The object of the present invention is to fix the temperature of the fixing member below the temperature suitable for fixing the toner image during the fixing operation of the toner image on the long recording medium without using a fixing member having a particularly large heat capacity. An image forming apparatus capable of preventing or effectively suppressing a problem that the amount of heat applied to the toner on the long recording medium by the fixing member is less than an amount suitable for fixing the toner image, and a fixing apparatus An auxiliary power supply device is provided.

  In order to achieve the above object, the present invention forms a toner image on an image carrier, transfers the toner image to a long recording medium longer than a standard size, and transfers the toner image to the long recording medium. The image forming apparatus fixes the image to a long recording medium using a fixing device, the fixing device including a fixing member, a pressure member pressed against the fixing member, and a temperature detecting unit that detects a temperature of the fixing member. And a heating means for heating the fixing member, and a long recording medium carrying a toner image is passed through a nip portion between the fixing member and the pressure member, and heat and pressure are applied to the toner of the toner image at the time of passing. In the image forming apparatus for fixing the toner image to the long recording medium, the heating means includes a main heating member supplied with power from a main power source, and a plurality of auxiliary units that can be switched between series connection and parallel connection. Auxiliary heating powered by power supply The pressure contact force between the fixing member and the pressure member is stepwise so that the width of the nip portion is larger when the temperature of the fixing member is lower than when the temperature of the fixing member is high. A pressure adjusting means for changing, a slope of a change in temperature of the fixing member detected by the temperature detecting means, and the fixing member is configured to detect the long recording medium and the toner on the long recording medium at the nip portion. The heat supply supplied to the power supply, the calculation means for calculating the gradient of the change in the heat supply, and the fixing member while heating the fixing member only by the main heating member supplied with power from the main power supply. When fixing the toner image by passing a long recording medium between the pressure members, the temperature of the fixing member detected by the temperature detection unit cannot maintain the temperature necessary for fixing the toner image, And the above The fixing member becomes less than a predetermined fixing temperature threshold that is determined to be unable to continue supplying a heat amount suitable for fixing the toner image to the toner on the long recording medium. When at least one of the absolute value of the gradient of the temperature change of the member and the absolute value of the gradient of the supply heat quantity is equal to or greater than a predetermined gradient threshold, the plurality of auxiliary power supplies are connected in series, When electric power is supplied to the auxiliary heating member from the plurality of auxiliary power supplies, and the absolute value of the inclination of the temperature change of the fixing member and the absolute value of the inclination of the change in the supply heat amount are both smaller than the inclination threshold values. And an auxiliary power supply output control means for connecting the plurality of power supplies in parallel and supplying power to the auxiliary heating member from the plurality of auxiliary power supplies. ).

  In the image forming apparatus according to claim 1, the pressure adjusting unit may be configured such that the width of the nip portion is set when the temperature of the fixing member detected by the temperature detecting unit becomes equal to or lower than the fixing temperature threshold. It is advantageous that the pressure contact force between the fixing member and the pressure member is adjusted so as to be the largest (claim 2).

  Furthermore, in the image forming apparatus according to claim 1 or 2, the auxiliary power source is configured by a chargeable / dischargeable electric double layer capacitor, and when power is not supplied from the main power source to the main heating member, It is advantageous if the electric double layer capacitor is configured to be charged (Claim 3).

  Further, in the image forming apparatus according to claim 1 or 2, it is advantageous that the auxiliary power source is constituted by a fuel cell that can be used repeatedly after changing fuel (claim 4).

  5. The image forming apparatus according to claim 4, wherein the fuel cell includes means for detecting the remaining amount of fuel, means for displaying the remaining amount of fuel, and replacement of fuel when the remaining amount of fuel falls below a certain value. It is advantageous that a means for prompting is provided (claim 5).

  In order to achieve the above object, the present invention provides a plurality of auxiliary power supplies that can be switched between series connection and parallel connection, and the fixing member when the temperature of the fixing member is equal to or lower than a predetermined fixing temperature threshold. At least one of the absolute value of the slope of the temperature change and the absolute value of the slope of the change in the amount of heat supplied to the long recording medium and the toner on the long recording medium by the fixing member. When this is the case, the plurality of auxiliary power supplies are connected in series, power is supplied from the plurality of auxiliary power supplies to the auxiliary heating member for heating the fixing member, and the absolute value of the gradient of the temperature change of the fixing member, When the absolute value of the gradient of the change in the amount of supplied heat is smaller than each gradient threshold value, the plurality of power sources are connected in parallel, and power is supplied from the plurality of auxiliary power sources to the auxiliary heating member for heating the fixing member. Auxiliary power supply output It proposes an auxiliary power supply for a fixing device comprising a control unit (claim 6).

  According to the present invention, during the fixing operation of the toner image on the long recording medium, the temperature of the fixing member decreases below the temperature suitable for fixing, and the amount of heat that the fixing member supplies to the toner on the long recording medium. However, it is possible to prevent or effectively suppress the problem that the amount of toner is less than the amount suitable for fixing the toner image.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  The image forming apparatus shown in FIG. 1 includes a paper feeding unit 1, an image forming unit 2 disposed on the paper feeding unit 1, and an image reading unit 3 disposed on the image forming unit 2. have. A document (not shown) placed on the document table 4 of the image reading unit 3 is aligned in the width direction by a side fence (not shown) and then fed in the direction of arrow A by the paper feed roller 5. , And passes under the contact type reading device 6. A document width detection sensor and a document length detection sensor (not shown) are provided on the document table 4, and the document size is detected by these sensors. The contact-type reading device 6 has a rod lens array and an image sensor not shown in the drawing. When a document passes under the contact-type reading device 6, an LED array, a fluorescent lamp, or the like is placed on the document. The light from the light source is irradiated, the reflected light passes through the rod lens and reaches the image sensor, and a document image is formed on the image sensor and subjected to photoelectric conversion. The document whose image has been read is discharged to the discharge tray 7 or 8 as indicated by an arrow B or C. In addition, the image reading unit 3 is provided with an operation unit (not shown) for inputting a print operation start instruction, information such as the number of repeat copies and the length of a sheet.

  The image forming unit 2 includes a drum-shaped photoconductor 9 which is an example of an image carrier. The photoconductor 9 is driven to rotate counterclockwise in FIG. 1, and at this time, the photoconductor 9 is charged by a charging device 10. Is done. On the other hand, the image signal read by the contact-type reading device 6 is subjected to image processing, light corresponding to the image signal is emitted from the exposure device 11 provided with the LED array, and the light is irradiated on the charged photoreceptor surface. . As a result, an electrostatic latent image is formed on the photoconductor 9, and the latent image is visualized as a toner image by the developing device 12.

  On the other hand, the paper feed unit 1 has two upper and lower roll paper trays 13 and 14, and the roll paper trays 13 and 14 each have roll paper 15, 16, 17 and 18 wound around a paper tube. Are rotatably supported, and paper feed rollers 19, 20, 21, and 22 are arranged corresponding to the respective roll papers. Each of the roll paper trays 13 and 14 can be pulled out to the left in FIG. 1 from the apparatus housing, and roll paper can be set or jammed with the roll paper tray being pulled out. Paper is fed out from any selected roll paper 15, 16, 17 or 18 by the corresponding paper feed roller 19, 20, 21 or 22, and the paper is fed into the image forming unit 2. The paper is cut into a predetermined length by the cutter unit 23 or 24. The sheet is fed to the photoconductor 9 at a predetermined timing by the registration roller pair 25. At this time, the toner image formed on the photoconductor 9 is transferred to the paper by the action of the transfer device 26. Next, the sheet is separated from the photosensitive member 9 by the action of the separating device 27, and subsequently conveyed to the fixing device 29 by the conveying belt 28. The transfer residual toner adhering to the surface of the photoreceptor 9 after the toner image is transferred is removed by the cleaning device 50. When the paper passes through the fixing device 29, the transferred toner image is fixed on the paper. The paper that has passed through the fixing device 29 is discharged by a paper discharge roller 30 or 31 to a paper discharge unit 32 constituted by the upper surface of the image forming unit 2 or a paper discharge unit 33 disposed behind the image forming unit 2. The

  The image forming apparatus shown in FIG. 1 forms an image on the paper that is fed out from the roll papers 15 to 18 and cut, so that the length of the paper can be selected substantially freely. Therefore, the length of the paper can be made longer than the length of the standard size, and the length can be as long as, for example, 15 m. A recording medium other than paper can be used as the long recording medium. In the following description, a long recording medium made of paper that has been fed from roll paper and cut by the cutter unit 23 or 24, or already cut is referred to as a long recording medium P (see FIG. 2). To.

  In the image forming apparatus shown in FIG. 1, a toner image is formed on an image carrier made of a photoreceptor 9, and the toner image is transferred to a long recording medium longer than a standard size. The toner image transferred to the toner image is fixed on the long recording medium by the fixing device 29. The toner image on the photosensitive member is primarily transferred to the intermediate transfer member, and the toner image on the intermediate transfer member is transferred to the intermediate transfer member. It can also be configured to perform secondary transfer onto a long recording medium. In this case, the intermediate transfer member constitutes an image carrier, and the toner image formed on the image carrier is transferred to a long recording medium.

  FIG. 2 is an enlarged sectional view of the fixing device 29 shown in FIG. The fixing device 29 shown here detects a fixing roller 36 as an example of a fixing member, a pressure roller 37 as an example of a pressure member in pressure contact with the fixing roller 36, and the surface temperature of the fixing roller 36. A temperature detecting unit 38 and a heating unit 39 for heating the fixing roller 36 are provided. The fixing roller 36 illustrated in FIG. 2 includes a cylindrical metal tube 40 made of aluminum or carbon steel and a release layer 41 laminated on the outer peripheral surface of the metal tube 40. The pressure roller 37 includes a cylindrical cored bar 42 made of a metal such as aluminum or carbon steel, an elastic layer 43 made of silicone rubber or the like fixed to the outer peripheral surface of the cored bar, and the elastic layer 43 It is comprised by the mold release layer 44 laminated | stacked on the outer peripheral surface (refer also FIG. 19). The temperature detection unit 38 includes, for example, a thermistor that is in contact with the peripheral surface of the fixing roller 36, or another temperature sensor. The heating means 39 shown in FIG. 2 includes a main heating member 39A that generates heat when power is supplied from a main power source, which will be described in detail later, and an auxiliary heating member 39B that generates heat when power is supplied from an auxiliary power source. The heating members 39A and 39B are disposed inside the fixing roller 36. As the heating members 39A and 39B, for example, a halogen heater, a nichrome wire heater, an IH heater, or the like can be used.

  During the toner image fixing operation, the fixing roller 36 is driven to rotate counterclockwise in FIG. 2 by a driving device (not shown), and the pressure roller 37 is rotated in the clockwise direction in FIG. To do. At this time, the fixing roller 36 is heated by the heating unit 39 in a manner described later. The long recording medium P carrying the toner image T is passed through the nip portion N between the fixing roller 36 and the pressure roller 37 in a direction in which the toner image T is in contact with the fixing roller 36. Heat and pressure are applied to the toner of the image T to fix the toner image on the long recording medium P.

  In the fixing device 29 shown in FIG. 2, since the long recording medium P having a long length passes between the fixing roller 36 and the pressure roller 37, the heat of the fixing roller 36 is applied to the long recording medium P. Continue to be robbed for a long time. Therefore, while the long recording medium P passes between the fixing roller 36 and the pressure roller 37, the temperature of the fixing roller 36 becomes lower than the temperature suitable for fixing the toner image, or the fixing roller 36 However, the amount of heat supplied to the toner on the long recording medium P may be less than the amount suitable for fixing the toner image.

  Therefore, in the fixing device of this example, the fixing roller 36 is fixed so that the width of the nip portion N between the fixing roller 36 and the pressure roller 37 is larger when the surface temperature of the fixing roller 36 is lower than when the surface temperature is high. Pressure adjusting means for changing the pressure contact force between the roller 36 and the pressure roller 37 stepwise is provided. Here, the width of the nip portion N is a width along the conveyance direction of the long recording medium of the nip portion where the fixing member and the pressure member are in contact with each other. In the case of the fixing device 29 shown in FIG. The width W of the nip portion N where the fixing roller 36 and the pressure roller 37 are in pressure contact with each other along the long recording medium conveyance direction.

  18 to 20 are views showing an example of the pressure adjusting means described above. As shown in FIG. 19, a shaft 51 fixed to the pressure roller 37 extends through the pressure roller 37, and a portion of the shaft 51 located inside the pressure roller 37. A disc 52 that is in contact with the inner peripheral surface of the pressure roller 37 is fixed. As shown in FIGS. 18 and 19, bearings 53 are fitted to the respective longitudinal ends of the shaft 51, and the shaft 51 is rotatably assembled to the casing 54 via the bearings 53. It has been. At that time, each bearing 53 is fitted in a long hole 56 formed vertically on each side plate 55 of the casing 54 so as to be slidable in the longitudinal direction. Further, the fixing roller 36 is supported at its end in the longitudinal direction on each side plate 55 of the casing 54 through a bearing, but is rotatably supported.

  A pressure lever 57 is arranged below each bearing 53, and one end of each pressure lever 57 swings on the side plate 55 of the casing 54 via a pin 58 as shown in FIG. One end of a tension spring 59 is locked to the other end of the pressure lever 57. The other end of the tension spring 59 is locked to the lower part of the movable plate 60. A long hole 61 is formed in the movable plate 60, and the long hole 61 is slidably fitted to a pin 66 protruding from the side plate 55. Thereby, the movable plate 60 can move up and down along the side plate 55. Further, the rotation shaft 62 can rotate with respect to the side plate 55 in the side plate 55, but passes through the position immovable, and the cam 63 is fixed to the rotation shaft 62. The rotating shaft 62 extends through a long hole (not shown) formed vertically on the movable plate 60. Accordingly, the movable plate 60 can move up and down a predetermined stroke without being obstructed by the rotating shaft 62, and the bent portion 64 at the upper portion of the movable plate 60 is pressed against the cam 63 by the action of the tension spring 59. To do. FIG. 18 shows a pressure lever 57 on one end side of the pressure roller 37, a tension spring 59, a movable plate 60, and a cam 63 fixed to the rotating shaft 62. The other end portion side of 37 has the same configuration.

  Further, a gear 65 is fixed to one end of the rotary shaft 62 described above, and this gear 65 is drivingly connected to a motor (not shown) through an intermediate gear (not shown) meshed therewith. Yes.

The rotation of the motor described above is transmitted to the gear 65, and the gear 65 and the cam 63 rotate, whereby the movable plate 60 moves to the vertical position. At this time, the more the movable plate 60 occupies the upper position, the stronger the pressure contact force between the pressure roller 37 and the fixing roller 36, and the nip portion between the fixing roller 36 and the pressure roller 37 shown in FIG. The width W of N increases. In the illustrated example, as shown in FIG. 20, the width W of the vertical position and the nip portion N of the movable plate 60 is switched to 5 stages, the temperature T _H of the fixing roller 36 heated by the heating means 38 is lowered The vertical position of the movable plate 60 is switched so that the width W of the nip portion N is increased. That is, when T _H > 180 ° C., as shown in FIG. 20A, the movable plate 60 occupies the lowest position, and the width W of the nip portion N shown in FIG. When 180 ° C. ≧ T _H > 170 ° C., as shown in FIG. 20B, the movable plate 60 occupies the next lowest position, and the width W of the nip portion N is W2. Similarly, when 170 ° C. ≧ T _H > 160 ° C., 160 ° C. ≧ T _H > 150 ° C., and 150 ° C. ≧ T _H , the movable plate 60 is shown in (c), (d), (e) of FIG. The width W of the nip portion N is W3, W4, and W5, respectively. Magnitude relationship between the width of each nip N is W1 <W2 <W3 <W4 < W5, when the temperature _{T H} of the fixing roller 36 becomes 0.99 ° C. or less, the width W of the nip portion N is a maximum of W5 Become. Thus, as the temperature T _H of the fixing roller 36 is low, so that the width W of the nip portion N becomes large, the contact pressure between the fixing roller 36 and the pressure roller 37 is to be switched stepwise. Therefore, when a long long recording medium lengths between the fixing roller 36 and the pressure roller 37 to pass through the heat of the fixing roller 36 is absorbed by the elongate recording medium, the temperature T _H of the fixing roller 36 Even if it decreases, the width W of the nip portion N increases along with the decrease, so that the decrease in the amount of heat supplied from the fixing roller 36 to the toner on the long recording medium is compensated for, and the fixing failure of the toner image occurs. Can be prevented. Note that the temperature T _H of the fixing member or fixing roller 36, means the temperature of the fixing member or the surface of the fixing roller 36.

However, only the above-described configuration, the temperature T _H of the fixing roller 36 can not prevent the lower defect than the temperature suitable for the fixing of the toner image. Further, the temperature T _H is greatly reduced in the fixing roller 36, for example, that if the temperature T _H is as equal to or less than 0.99 ° C. described above, the temperature T _H of the fixing roller 36, necessary for fixing the toner image In addition to being difficult to maintain at a proper temperature, it is difficult for the fixing roller 36 to continue to supply a heat amount suitable for fixing the toner image to the toner on the long recording medium.

Therefore, in the image forming apparatus of this example, as described above, the heating unit 39 provided in the fixing device 29 includes the main heating member 39A to which power is supplied from the main power source including the AC power source and the power from the auxiliary power source. And the auxiliary heating member 39B to which the toner image is supplied cannot be maintained at a temperature necessary for fixing the toner image, and the fixing roller 36 is in contact with the toner on the long recording medium at the nip portion N. the temperature T _H of the fixing roller where it is determined that it can not to heat continuously supply suitable for fixing when the fixing temperature threshold value T _lim of the temperature T _H of the fixing roller 36 detected by the temperature detecting means 38 is fixed When the temperature is higher than the temperature threshold T _lim , the fixing roller 36 is heated only by the main heating member 39A that is supplied with power from the main power source and generates heat, and is detected by the temperature detecting means 38. And if the temperature T _H of the fixing roller 36 is equal to or less than the fixing temperature threshold value T _lim is also an auxiliary heating member 39B, by supplying electric power from the auxiliary power to be described later in detail, to generate heat and the auxiliary heating member 39B The fixing roller 36 is rapidly heated by both the main heating member 39A and the auxiliary heating member 39B. Below, an example of the control aspect relevant to these is demonstrated.

3 and 4 are flowcharts showing an example of a printing operation for forming an image on a long recording medium. 1 to 4, when a print command is inputted, first, the temperature T _H of the fixing roller 36 by the temperature detecting means 38 is detected, elongated recording medium to the nip portion of the fixing roller 36 and the pressure roller 37 , And a temperature at which the fixing operation of the toner image on the long recording medium can be started (hereinafter referred to as a paper passing temperature) T _t is determined (S1 in FIG. 3). if the temperature T _H of has reached the sheet-passable temperature T _t, the start of rotation of the fixing roller 36 and the pressure roller 37 shown in FIG. 2, fixing a long recording medium P bearing the toner image T The toner image is fed between the roller 36 and the pressure roller 37, and the toner image fixing operation is started (S3 in FIG. 3). In the toner image fixing operation, the trailing edge of the long recording medium exits between the fixing roller 36 and the pressure roller 37 from the time when the leading edge of the long recording medium enters between the fixing roller 36 and the pressure roller 37. This is the operation up to the point in time. On the other hand, in S1, when the temperature T _H of the fixing roller 36 does not reach the sheet-passable temperature T _t, and heat the fixing roller 36 by the power from the main power supply continues to supply the main heating member 39A (in FIG. 3 S2) and S1 → S2 are repeated. At this stage, power is not supplied from the auxiliary power source to the auxiliary heating member 39B, and the fixing roller 36 is heated only by the main heating member 39A. Further, the temperature at which paper can be passed varies depending on the length of the long recording medium. The longer the length of the long recording medium, the higher the energizable temperature. The energizable temperature is, for example, about 160 ° C. to 200 ° C.

When the fixing operation is started, as described above, depending on the surface temperature T _H of the fixing roller 36 detected by the temperature detecting means 38, the width W of the nip portion N is adjusted stepwise.

Further, after the start of the fixing operation, the supply heat amount Q _H supplied from the fixing roller 36 to the long recording medium and the toner on the long recording medium at the nip portion N is calculated (S4 in FIG. 3). As is known per se, this supply heat quantity Q _H is obtained, for example, by the following equation (1).

Here, c is a time (sec) required for a certain point on the long recording medium to pass through the nip portion N. Further, √T ₀ is the heat acquisition degree of the toner on the recording medium and the recording medium (J / (cm ² ° C√sec)), and √R is the heat acquisition degree (J / of the release layer 41 of the fixing roller 36). (Cm ² ° C√sec)). Further, T _TC is the temperature of the recording medium before contacting the fixing roller 36 and the toner carried thereon, and this temperature T _TC is normally about 20 ° C. It T _H is the surface temperature of the fixing roller 36 detected by the temperature detecting means 38 are as described above.

Then, the supply heat quantity Q _H described above, along with whether it is less fixing non heat Q _NG that can not fix the toner image is checked, the temperature T _H of the fixing roller 36 can not fix the toner image fixing non temperature T _NG It is determined whether or not the temperature is below (in this example, this is 140 ° C.) (S5 in FIG. 4). When at least one of Q _H ≦ Q _NG and T _H ≦ T _NG is reached, the printing operation is interrupted (S6 in FIG. 3). In this case, the recording medium fed from one of the roll papers is immediately cut by the cutter unit 23 or 24, and the toner image forming operation on the photosensitive member 9 is stopped, and the recording medium is discharged. The paper part 32 or 33 is discharged. In this way, the long recording medium carrying the unfixed toner image is prevented from continuing to be discharged as it is. After the printing operation is interrupted, a message prompting the user to reset the sheet passing temperature T _t to a large value is displayed on the operation unit provided in the image reading unit 3, and the user can pass the sheet in S7 of FIG. When it is determined that the temperature T _t has been largely reset, the process proceeds to S2, and the operation from S1 described above is resumed. If the user does not reset the paper passing temperature, the printing operation is terminated.

On the other hand, in S5 of FIG. 3, toner supply heat supplied Q _H on the fixing roller 36 is an elongated recording medium that long recording medium exceeds the fixing non heat Q _NG, moreover the temperature T _H of the fixing roller 36 If it exceeds the unfixable temperature T _NG , the process proceeds to S8 in FIG. 3, and whether or not the rear end of the long recording medium has exited the nip N between the fixing roller 36 and the pressure roller 37 by a sensor (not shown). That is, it is determined whether or not the long recording medium has completed the fixing operation after the paper passing through between the fixing roller 36 and the pressure roller 37 is completed. When the passing of the long recording medium is completed and the fixing operation of the toner image is completed, the rotation of the fixing roller 36 and the pressure roller 37 is temporarily stopped (S9 in FIG. 3), and then the set number of sheets is set. The arrival is determined (S10 in FIG. 3), and if not reached, the operation from S1 is repeated, and if it has reached, the printing operation is terminated. When the long recording medium is passed, the pressure adjusting means adjusts the pressure contact force between the fixing roller 36 and the pressure roller 37 to be the weakest.

When the trailing edge of the long recording medium has not yet come out of the nip N between the fixing roller 36 and the pressure roller 37 and the toner image is being fixed, the temperature T _{H of the} fixing roller 36 is maintained. Is determined to be equal to or lower than the above-described fixing temperature threshold T _lim (S11 in FIG. 4). At that time, in the image forming apparatus of this embodiment, the fixing temperature threshold value T _lim, and the temperature T _H of the fixing roller 36 when adjusting the maximum W5 width W of the nip portion N by the aforementioned pressure adjusting means They are set equally and both temperatures are 150 ° C. Pressure adjusting means, when the temperature T _H of the fixing roller 36 detected by the temperature detecting means 38 becomes equal to or less than the fixing temperature threshold value T _lim, such that the width W of the nip portion N is maximized, and the fixing roller 36 The pressure contact force of the pressure roller 37 is adjusted.

In S11 in FIG. 4, when the temperature _{T H} of the fixing roller 36 was judged to be higher than the fixing temperature threshold value _{T lim,} without supplying power to the auxiliary heating member 39B, the fixing roller by the main heating member 39A 36 The toner image fixing operation is continued while heating (S15 in FIG. 4). On the other hand, the temperature T _H of the fixing roller 36 can not maintain the temperature necessary for fixing the toner image, and at the nip N, the fixing roller 36 the toner on a long recording medium, suitable for fixing the toner image When the temperature becomes equal to or lower than a predetermined fixing temperature threshold T _lim determined to be unable to continue to supply the amount of heat, power is also supplied from the auxiliary power source to the auxiliary heating member 39B, and the main heating member 39A and the auxiliary heating member 39B Are heated together to heat the fixing roller 36. As a result, a large amount of heat can be applied to the fixing roller 36, the fixing roller 36 supplies a heat amount suitable for fixing the toner image to the toner on the long recording medium, and the temperature T of the fixing roller 36. It is possible to maintain _H at a temperature suitable for fixing the toner image. When the temperature T _H of the fixing roller 36 is lowered below the fixing temperature threshold value T _lim is the aforementioned pressure adjusting means, the width W of the nip portion N between the fixing roller 36 and the pressure roller 37 is largest Since the width W5 is adjusted, the width W of the nip portion N cannot be increased any more. Depending on the adjustment of the width W of the nip portion N, the amount of heat supplied to the toner on the long recording medium can be reduced. Although the power cannot be increased more than that, power is also supplied from the auxiliary power source to the auxiliary heating member 39B of the heating means 39, so that the temperature of the fixing roller 36 is maintained at a temperature suitable for fixing and the toner on the long recording medium is used. On the other hand, an amount of heat suitable for fixing the toner image can be supplied.

At that time, the temperature T _H of the fixing roller 36 is sharply decreased, and if the temperature T _H is equal to or less than the fixing temperature threshold value T _lim, the temperature T _H is gradually reduced to a fixing temperature threshold value of the fixing roller 36 Although there are a case where a T _lim or less, in the former case than in the latter case also, when not heated fixing roller 36 gives a large amount of heat to the fixing roller 36, the temperature T _H of the fixing roller 36 May be lower than the temperature suitable for fixing the toner image. Similarly, toner supplying heat supplied Q _H on the elongate recording medium fixing roller 36 is sharply decreased, and if the temperature T _H is equal to or less than the fixing temperature threshold value T _lim of the fixing roller 36, the supply amount of heat Q _H is decreased slowly, there is a case where the temperature T _H of the fixing roller 36 is equal to or less than the fixing temperature threshold value T _lim, the former case, a large amount of heat in the fixing roller 36 than in the latter case To heat the fixing roller 36.

Therefore, in the image forming apparatus of the present embodiment, a plurality of auxiliary power can be switched to a series connection and the parallel connection are provided, the temperature T _H of the fixing roller 36 detected by the temperature detecting means 38 changes calculates a slope (fixing roller per unit time temperature T variation in _{H) dT H / dt = K} T, as described above, the elongate recording medium fixing roller 36 at the nip N and its elongated recording medium calculates the amount of heat supplied _{Q H} is supplied to the toner of the upper (S4 in FIG. 3), and (the amount of change in the supply heat quantity _{Q H} per unit _time) the slope of change of the amount of heat supplied _{Q H dQ H / dt = K} Q An arithmetic means for calculating is provided. Slope is predetermined _| Then, the slope K _T of the change in the fixing roller temperature T _H detected by the temperature detecting means 38 is calculated in increments of a predetermined time, in S12 of FIG. 4, the absolute value of the slope | K T It is determined whether or not the threshold value | K _Tlim | is greater than or _{equal to the} threshold value, and the slope K _Q of the supplied heat quantity Q _H is calculated in steps of a certain time. In S12 of FIG. 4, the absolute value | K _Q | It is checked whether the threshold value | K _Qlim | At that time, the absolute value of the slope of the temperature change of the fixing roller 36 | _{K T} | and the absolute value of the slope of the supply heat quantity _{Q H} | _{K Q} | are both its respective gradients threshold _{| K Tlim} | and _{| K QLIM} | than When it is small, a plurality of auxiliary power supplies are connected in parallel by the auxiliary power supply output control means, and power is supplied from the plurality of auxiliary power supplies to the auxiliary heating member 39B (S13 in FIG. 4). At the same time, power from the main power supply is supplied to the main heating member 39A, and the fixing operation of the toner image is continued while heating the fixing roller 36 by both the main heating member 39A and the auxiliary heating member 39B (S15 in FIG. 4). ). On the other hand, when at least one of the absolute values of inclinations | K _T | and | K _Q | is _{equal to} or greater than a predetermined inclination threshold value | K _Tlim | and | K _Qlim | Auxiliary power supplies are connected in series, and power is supplied from the plurality of auxiliary power supplies to the auxiliary heating member 39B (S14 in FIG. 4), and power from the main power supply is supplied to the main heating member 39A, thereby supplying the main heating member 39A. The toner image fixing operation is continued while heating the fixing roller 36 with both the auxiliary heating member 39B (S15 in FIG. 4). When a plurality of auxiliary power supplies are connected in series, a larger amount of power can be supplied to the auxiliary heating member 39B than when the plurality of auxiliary power supplies are connected in parallel. Therefore, the absolute value of the temperature drop gradient of the fixing roller 36 | K _T | and the absolute value of the decrease in the slope of the supply heat quantity Q _H | K Q _| even greater, giving a large amount of heat in the fixing roller 36, the temperature T _H of the fixing roller 36 is suitable for fixing the toner image temperature prevents the lower than, and the fixing roller 36, toner supplying heat supplied Q _H on the long recording medium can prevent the less than the amount of heat which is suitable for fixing the toner image.

As described above, in the image forming apparatus of this example, the heating unit 39 of the fixing device 29 has a plurality of auxiliary units that can be switched between the main heating member 39A to which power is supplied from the main power source and the series connection and the parallel connection. The auxiliary heating member 39B is supplied with power from a power source, and the fixing roller 36 and the pressure roller 37 are heated while the fixing roller 36 is heated only by the main heating member 39A supplied with power from the main power source. when performing fixing of the toner image is passed through the elongated recording medium between the temperature T _H of the fixing roller 36 detected by the temperature detecting means 38 can not maintain the temperature necessary for fixing the toner image, and at the nip portion N, the toner on a long recording medium fixing roller 36, it it below a predetermined fixing temperature threshold value T _lim it is determined that it can not continue to supply heat which is suitable for fixing a toner image If the, the absolute value of the slope of the temperature change of the fixing roller 36 | and the absolute value of the slope of the change in the amount of heat supplied _{Q H | | K T K Q} | of at least one of, a predetermined inclination threshold respectively | When K _Tlim | and | K _Qlim | are greater than or _{equal to} each other, a plurality of auxiliary power supplies are connected in series, power is supplied from the plurality of auxiliary power supplies to the auxiliary heating member 39B, and the absolute gradient of the temperature change of the fixing roller 36 is absolute. When the value | K _T | and the absolute value | K _Q | of the gradient of the change in the supply heat quantity Q _H are both smaller than the inclination threshold values | K _Tlim | and | K _Qlim |, a plurality of power supplies are connected in parallel. In addition, auxiliary power output control means for supplying electric power from the plurality of auxiliary power supplies to the auxiliary heating member 39B is provided. The specific configuration of the auxiliary power output control means will be described later.

According to the above-described configuration, especially without using a fixing roller 36 having a large heat capacity, during the fixing operation of the toner image on the elongate recording medium, the temperature of the temperature T _H of the fixing roller 36 is suitable for fixing a toner image Or a problem that the amount of heat supplied to the toner on the long recording medium by the fixing roller 36 is less than the amount suitable for fixing the toner image can be prevented.

  As the auxiliary power source described above, it is desirable to use a chargeable / dischargeable electric double layer capacitor or a fuel cell that can be used repeatedly by replacing the fuel.

  Next, a more specific example of the printing operation described above will be clarified with reference to FIGS.

FIGS. 5 to 10 show an example in which an electric double layer capacitor is used as an auxiliary power source. FIGS. 5 and 6 show that the fixing roller 36 only generates heat from the main heating member supplied with power from the main power source. The operation example in the case of heating is shown. 5 and 6, at time t _0, power from the main power supply consisting of an AC power source to the main heating member 39A starts to be supplied. This fixing roller 36 generates heat is the main heating member 39A is heated by, as shown in FIG. 5 (A), the temperature T _H is above the sheet passing possible temperature T _t of the fixing roller 36 at the time of t ₁ The start-up operation of the fixing device 29 is finished. In the example shown here, the fixing roller 36 is heated without causing the auxiliary heating member 39B to generate heat during the start-up operation, but power is also supplied to the auxiliary heating member 39B from an auxiliary power source including an electric double layer capacitor. If the auxiliary heating member 39B also generates heat, the startup time of the fixing device 29 can be further shortened.

After completion of the start-up operation of the fixing device 29 as described above, such that the temperature T _H of the fixing roller 36 is maintained at a sheet-passable temperature T _t, the power supply is turned on to the main heating member 39A, It is turned off ((C) in FIG. 6). This state is a standby state of the fixing device 29. At this time, when the charging voltage of the electric double layer capacitor is detected by a voltage sensor (not shown) and there is room for charging in the electric double layer capacitor, When power is not supplied from the power source to the main heating member 39A, the electric double layer capacitor is charged ((C) and (E) in FIG. 6). As a result, the electric double layer capacitor can be efficiently charged, and a large amount of electric power can be secured when the electric double layer capacitor is used. During the start-up operation and standby, the fixing roller 36 and the pressure roller 37 do not rotate and are stopped.

5 and the rotation of the fixing roller 36 and the pressure roller 37 at the time of t ₂ is started in FIG. 6, the feed of the elongated recording medium to the nip portion between the fixing roller 36 and the pressure roller 37 Be started. The passing of the long recording medium to the nip portion N is started, and the fixing operation of the toner image on the long recording medium is started. As shown in FIG. 6C, the reason why the power consumption of the main heating member 39A is less after the start of the fixing operation than when the main heating member 39A is started up is that the AC power supply is increased with the start of the fixing operation. This is because the AC power of the main power source is converted to DC power and used for the rotation operation of the fixing roller 36.

When the fixing operation at the time of t ₂ is started, since the heat of the fixing roller 36 is absorbed by the elongate recording medium, the temperature T _H of the fixing roller 36 as shown in FIG. 5 (A) is gradually but it decreases, in the operation example shown in FIG. 5 and FIG. 6, without the temperature T _H of the fixing roller 36 is equal to or less than the fixing temperature threshold value T _lim, to end the fixing operation at the time of t _3. That is, at this time, the trailing end of the long recording medium exits the nip portion N between the fixing roller 36 and the pressure roller 37, and the rotation of the fixing roller 36 and the pressure roller 37 is stopped.

Upon completion of the fixing operation, the main heating member 39A, since the power from the main power supply is continuously supplied, the temperature T _H of the fixing roller 36 rises, the temperature T _H of the fixing roller 36 at the time of t ₄ can be fed Temperature _Tt is reached ((A) in FIG. 5 and (C) in FIG. 6). On subsequent stand, so that the temperature T _H of the fixing roller 36 is maintained at a sheet-passable temperature T _t, the power supply to the main heating member 39A from the main power supply is turned on, it is turned off ((C in FIG. 6 )) If there is still room for charging in the electric double layer capacitor, the electric double layer capacitor is charged when power is not supplied from the main power source to the main heating member 39A ((C) and (E) in FIG. 6). )).

Further, the time from the time point t ₃ t _4, and also supplied the electric power from the electric double layer capacitor to the auxiliary heating member 39B, both the heating member 39A, when configured to heat the fixing roller 36 by 39B, the fixing roller temperature T _H of 36 it is possible to shorten the time to reach the sheet-passable temperature T _t.

In the operation example shown in FIGS. 7 and 8, and from time t ₀ to t _2, t ₃ subsequent operations, operation and change is not shown in FIGS. Different place, at time _{T 1,} in that the temperature _{T H} of the fixing roller 36 is equal to or less than the fixing temperature threshold value _{T lim.} At this time, as can be seen from FIG. 7B, the absolute value | K _T | of the change in temperature of the fixing roller 36 is smaller than the inclination threshold value | K _Tlim | and is not shown in the figure. Since the absolute value | K _Q | of the slope of the supplied heat quantity Q _H is smaller than the slope threshold value | K _Qlim |, a plurality of electric double layer capacitors are connected in parallel, and AC power is supplied from the main power source to the main heating member 39A. While supplying, electric power is also supplied from the plurality of electric double layer capacitors to the auxiliary heating member 39B to cause the auxiliary heating member 39B to generate heat, and the fixing roller 36 is heated by both the heating members 39A and 39B. Therefore, as can be seen from FIGS. 7C and 8D and 8E, the total consumption of the heating means 39, which is the sum of the power consumption of the main heating member 39A and the power consumption of the auxiliary heating member 39B. power is discontinuously increased at the time of T _1. Since the output of the electric double layer capacitor decreases as the discharge continues, the total power consumption of the heating means 39 gradually decreases from the time T ₁ ((C) in FIG. 7 and (E) in FIG. 8).

  Further, as can be seen from FIGS. 8E and 8F, when electric power is supplied from the electric double layer capacitor to the auxiliary heating member 39B, the electric double layer capacitor is not charged. For this reason, since all the AC power of the main power source can be supplied to the main heating member 39A, the fixing roller 36 can be effectively heated to raise its temperature.

In the operation example shown in FIGS. 9 and 10, in FIG. (A), as can be seen from (B), temperature fixing temperature threshold value T _lim next fixing roller 36 at time T _1, the fixing roller at this time The absolute value | K _T | of the temperature change gradient of 36 is equal to or greater than the gradient threshold value | K _Tlim |. For this reason, a plurality of electric double layer capacitors are connected in series regardless of whether or not the absolute value | K _Q | of the change in the supply heat quantity Q _H is equal to or greater than the inclination threshold value | K _Qlim | While supplying AC power from the power source to the main heating member 39A, large power is supplied to the auxiliary heating member 39B from a plurality of electric double layer capacitors connected in series to cause the auxiliary heating member 39B to generate heat. Since power is supplied to the auxiliary heating member 39B from the electric double layer capacitors connected in series, as can be seen from FIG. 10E, the power consumption of the auxiliary heating member 39B is as shown in FIG. As shown in FIG. 9C, the total power consumption of the heating means 39 is larger than in the case of FIG. 7C. As a result, the fixing roller 36 can be heated more rapidly and its temperature can be raised than when a plurality of electric double layer capacitors are connected in parallel and the electric power is supplied to the auxiliary heating member 39B.

  Other operations in the example shown in FIGS. 9 and 10 are the same as those shown in FIGS.

11 and 12 show an operation example when a fuel cell is used as an auxiliary power source. Again, at time T _1, the temperature T _H of the fixing roller 36 becomes less fixing temperature threshold value T _lim, the absolute value of the slope of the temperature change is not shown in this case FIG fixing roller 36 | K T _| is It is _{assumed that the} slope threshold value | K _Tlim | is smaller than the slope threshold value | K _Qlim | and the absolute value | K _Q | of the slope of the change in the supplied heat quantity Q _H is smaller than the slope threshold value | K _Qlim |. Accordingly, also in this case, a plurality of fuel cells are connected in parallel, and power is supplied from the plurality of fuel cells to the auxiliary heating member 39B while supplying AC power from the main power source to the main heating member 39A. The total power consumption of the heating means 39 at this time is the sum of the power consumption of the main heating member 39A and the power consumption of the auxiliary heating member 39B ((B) of FIG. 11 and (C), (D) of FIG. 12). .

  As can be seen from (E) of FIG. 12, since the fuel cell reduces the fuel by discharging, the remaining amount of fuel is constantly monitored, the remaining amount of fuel is displayed on the operation unit, and the remaining amount is indicated to the user. It is necessary to report. It is desirable that the fuel of the fuel cell be configured to be replaceable like a cartridge type so that it can be replaced when the user recognizes that the remaining amount of fuel is low. Thus, the fuel cell preferably includes means for detecting the remaining amount of fuel, means for displaying the remaining amount of fuel, and means for prompting the replacement of fuel when the remaining amount of fuel falls below a certain value.

  Next, specific configuration examples of the auxiliary power supply and the auxiliary power supply output control means will be described.

FIGS. 13 to 16 show auxiliary power output control means for connecting two electric double layer capacitors C1 and C2 in parallel or in series and supplying electric power from these electric double layer capacitors C1 and C2 to the auxiliary heating member 39B. It is a circuit diagram which shows an example. Each electric double layer capacitor C1, C2 is composed of a plurality of capacitor cells. Main switch _{S 5} is turned on the electric power supplied from the main power source 45 consisting of AC power to the main heating member 39A, off. The charger 46 serves to charge the two electric double layer capacitors C1 and C2 with electric power supplied from the main power supply 45. The switch _{S 2} switches and charging of the electric double layer capacitors C1, C2, power supply from the electric double layer capacitors C1, C2 to the auxiliary heating member 39B. Detection signal generated by the temperature detecting means 38 consisting of a contact with the thermistor on the surface of the fixing roller 36 is taken into CPU 47, a command from the CPU 47, the respective switches S ₁ to S ₅ are switching controlled.

Figure 13 shows a state in which the power from the main power source 45 by closing the main switch S ₅ is supplied to the main heating member 39A, and heating the main heating member 39A. At this time, the switches S ₃ and S ₄ connect both the electric double layer capacitors C 1 and C 2 in parallel, and the switch S ₂ is switched to the switch S ₁ side, but the switch S ₁ is turned off. The electric power of the double layer capacitors C1 and C2 is not supplied to the auxiliary heating member 39B.

During charging of the electric double layer capacitors C1, C2, as shown in FIG. 14, the main switch S ₅ is turned off, are cut off the power supply to the main heating member 39A from the main power source 45. At the same time, the switch S ₂ is switched to the side of the charger 46, the charger 46 charges the electric double layer capacitor C1, C2 in the power supplied from the main power supply 45.

When performing the fixing operation of the toner image while heating the fixing roller 36 in only the main heating member 39A, the temperature T _H of the fixing roller 36 becomes less fixing temperature threshold value T _lim detected by the temperature detecting means 38, moreover CPU47 The absolute value | K _T | of the change in temperature of the fixing roller 36 and the absolute value | K _Q | of the change in the supply heat quantity Q _H calculated in step S are the respective inclination threshold values | K _Tlim |, | K. _{qlim |} is smaller than the power from the main switch S ₅ is turned on the main power supply 45 as shown in FIG. 15 is supplied to the main heating member 39A, moreover connected both electric double layer capacitor C1, C2 is in parallel remains, the switch S2 is switched to the side of the switch S _1, the switch S ₁ is closed. Thereby, the electric power from the electric double layer capacitors C1 and C2 connected in parallel is supplied to the auxiliary heating member 39B, and both the heating members 39A and 39B generate heat.

Temperature _{T H} of the fixing roller 36 becomes less fixing temperature threshold value _{T lim,} and the absolute value of the slope of the temperature change of the fixing roller 36 | and the absolute value of the slope of the change in the amount of heat supplied _{Q H | | K T K Q} | When at least one of them is _{equal to} or greater than each of the slope threshold _values | K _Tlim | and | K _Qlim |, the switches S ₃ and S ₄ are switched as shown in FIG. 16 so that the electric double layer capacitors C1 and C2 are connected in series. Connected. Other states are the same as in FIG. Therefore, power from the main power supply 45 is supplied to the main heating member 39A, and power is supplied to the auxiliary heating member 39B from both electric double layer capacitors C1 and C2 connected in series.

FIG. 17 is a circuit diagram when two fuel cells C3 and C4 are used as auxiliary power supplies. In this case, the charger 46 shown in FIGS. 13 to 16 is not provided. 17, switches _{S 1} and _{S 5} are closed, both the fuel cell C3, C4 are connected in parallel, the fuel cell C3, C4 and the power each auxiliary heating member 39B and the main heating member 39A from the main power supply 45 The state being supplied is shown. Supplies power of the main power supply 45 to the main heating member 39B, when not supplying power from the fuel cell C3, C4 to the auxiliary heating member 39B, the switch S ₁ is open, connects the two fuel cell C3, C4 in series At that time, the switches S ₃ and S ₄ are switched in the same manner as in FIG.

  The auxiliary power supply output control means including the CPU 47 shown in FIGS. 13 to 17 and the auxiliary power supply are integrally assembled, so that a plurality of auxiliary power supplies that can be switched between series connection and parallel connection, and the temperature of the fixing member are predetermined. Of the temperature change of the fixing member and the inclination of the change in the amount of heat supplied by the fixing member to the long recording medium and the toner on the long recording medium. When at least one of the absolute values is equal to or greater than a predetermined inclination threshold value, a plurality of auxiliary power supplies are connected in series to supply power from the plurality of auxiliary power supplies to the auxiliary heating member for heating the fixing member, When the absolute value of the inclination of the temperature change of the fixing member and the absolute value of the inclination of the supply heat amount are both smaller than the inclination threshold value, a plurality of power supplies are connected in parallel to fix from the plurality of auxiliary power supplies. Material Can be an auxiliary heating member of use constitutes the auxiliary power supply 48 for the fixing device comprising an auxiliary power supply output control means for supplying electric power.

  The fixing device having the fixing member made of the fixing roller 36 and the pressure member made of the pressure roller 37 has been described above, but has the fixing member made of a fixing belt that is wound around a plurality of support rollers and driven to travel. The present invention can also be applied to a fixing device or a fixing device in which a pressure member is also configured as a pressure belt.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus. FIG. 3 is an enlarged cross-sectional view of a fixing device. 6 is a flowchart illustrating an example of an operation mode of the image forming apparatus. FIG. 6 is a flowchart illustrating an example of an operation mode of the image forming apparatus. FIG. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. 6 is a timing chart illustrating a more specific operation example of the image forming apparatus. It is a circuit diagram of a main power supply, an auxiliary power supply, and a fixing device. It is a circuit diagram of a main power supply, an auxiliary power supply, and a fixing device. It is a circuit diagram of a main power supply, an auxiliary power supply, and a fixing device. It is a circuit diagram of a main power supply, an auxiliary power supply, and a fixing device. It is a circuit diagram of a main power supply, an auxiliary power supply, and a fixing device. It is a perspective view which shows an example of a pressure adjustment means. It is a longitudinal cross-sectional view of a pressure roller. It is explanatory drawing which shows the height position of a movable plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 29 Fixing device 38 Temperature detection means 39 Heating means 39A Main heating member 39B Auxiliary heating member 45 Main power supply 48 Auxiliary power supply device C1, C2 Electric double layer capacitor C3, C4 Fuel cell P Long recording medium T Toner image

Claims (6)

A toner image is formed on the image carrier, the toner image is transferred to a long recording medium longer than a standard size, and the toner image transferred to the long recording medium is fixed to the long recording medium by a fixing device. In the image forming apparatus, the fixing device includes a fixing member, a pressure member pressed against the fixing member, a temperature detecting unit that detects the temperature of the fixing member, and a heating unit that heats the fixing member. Then, a long recording medium carrying a toner image is passed through the nip portion between the fixing member and the pressure member, and heat and pressure are applied to the toner of the toner image during the passage so that the toner image is transferred to the long recording medium. In the image forming apparatus fixed to
The heating means includes a main heating member supplied with power from a main power source, and an auxiliary heating member supplied with power from a plurality of auxiliary power sources that can be switched between series connection and parallel connection. A pressure adjusting means for stepwise changing the pressure contact force between the fixing member and the pressure member so that the width of the nip portion is larger when the temperature of the fixing member is lower than when the temperature is high; And a supply heat amount supplied to the long recording medium and toner on the long recording medium by the fixing member at the nip portion, and a supply heat amount thereof. A long recording medium between the fixing member and the pressure member while heating the fixing member only with the main heating member supplied with electric power from the main power source Let toner through When fixing is performed, the temperature of the fixing member detected by the temperature detecting unit cannot maintain the temperature necessary for fixing the toner image, and the fixing member is not on the long recording medium in the nip portion. The absolute value of the slope of the temperature change of the fixing member when the temperature becomes equal to or lower than a predetermined fixing temperature threshold that is determined to be unable to continue supplying an amount of heat suitable for fixing the toner image to the toner of When at least one of the absolute values of the gradient of change in the amount of supplied heat is equal to or greater than a predetermined gradient threshold value, the plurality of auxiliary power supplies are connected in series, and electric power is supplied from the plurality of auxiliary power supplies to the auxiliary heating member. When the absolute value of the inclination of the temperature change of the fixing member and the absolute value of the inclination of the supply heat amount are both smaller than the inclination threshold values, the plurality of power supplies are connected in parallel. An image forming apparatus characterized by comprising an auxiliary power supply output control means for supplying power to the auxiliary heating member from the auxiliary power of the plurality of. The pressure adjusting means is configured so that the width of the nip portion is maximized when the temperature of the fixing member detected by the temperature detecting means is equal to or lower than the fixing temperature threshold. 2. The image forming apparatus according to claim 1, wherein the pressure contact force is adjusted. The said auxiliary power supply is comprised by the electric double layer capacitor which can be charged / discharged, When the electric power is not supplied from the said main power supply to the said main heating member, the said electric double layer capacitor is charged. Image forming apparatus. The image forming apparatus according to claim 1, wherein the auxiliary power source includes a fuel cell that can be used repeatedly after changing fuel. 5. The image forming apparatus according to claim 4, wherein the fuel cell includes means for detecting a remaining amount of fuel, means for displaying the remaining amount of fuel, and means for prompting replacement of the fuel when the remaining amount of fuel falls below a certain value. apparatus. A plurality of auxiliary power sources that can be switched between series connection and parallel connection, and an absolute value of a slope of a temperature change of the fixing member when the temperature of the fixing member is equal to or lower than a predetermined fixing temperature threshold, and the fixing member When the absolute value of the slope of the change in the amount of heat supplied to the long recording medium and the toner on the long recording medium is equal to or greater than a predetermined slope threshold, the plurality of auxiliary power supplies are connected in series. To the auxiliary heating member for heating the fixing member from the plurality of auxiliary power supplies, the absolute value of the temperature change inclination of the fixing member and the absolute value of the inclination of the supply heat amount change, When both are smaller than the respective inclination thresholds, the fixing includes an auxiliary power supply output control means for connecting the plurality of power supplies in parallel and supplying electric power from the plurality of auxiliary power supplies to the auxiliary heating member for heating the fixing member. Auxiliary power for equipment Apparatus.

Images