JP5348301B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that properly fixes an image without reducing cpm in a print job after the last sheet of a plurality of sheets that is output in a single print request passes a nip part. <P>SOLUTION: An image forming apparatus 100 includes a fixing roller 14, a pressure roller 15, a fixing device 10 having a heat generator 2 for heating the fixing roller 14, and an electric storage device. After the last sheet of a plurality of sheets output in a single print request passes a nip part, if temperature of the pressure roller 15 is below a threshold temperature, the image forming apparatus 100 starts charging of the electric storage device, and performs standby operation of rotating the fixing roller 14 and the pressure roller 15 while heating the fixing roller 14 with power from an external power source. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to efficiency improvement of power saving of a fixing device, for example, efficiency improvement of power saving of an image forming apparatus such as a copying machine, a printer device, and a facsimile device using an electrophotographic system.

  In recent years, environmental problems have become important and image forming apparatuses such as copiers and printers have been saving power. In order to save power in the image forming apparatus, it is effective to lower the temperature of a fixing member such as a fixing roller or a fixing belt of the fixing apparatus when the image forming apparatus is not passing paper (for example, during standby). However, if the temperature of the fixing member during non-sheet passing is lowered, when the fixing device is used, the temperature of the fixing member must be increased to a certain temperature at which fixing can be performed again. Have to wait. As a result, it takes time until the image forming apparatus is ready for use, and the usability of the image forming apparatus deteriorates.

In order to avoid this, there are the following two measures (1) and (2).
(1) Shortening the heating time of the fixing member by assisting the power supply to the heating means of the fixing member by supplying electric power from the auxiliary power supply device (capacitor) to the heating means (capacitor heater) of the fixing member. (For example, refer to Patent Document 1).
(2) The thickness of the fixing member (especially the fixing roller) is reduced as a configuration for quickly raising the temperature of the fixing member.

  By the way, power supply assistance from the auxiliary power supply device (capacitor) to the fixing member heating means is performed not when the fixing member is heated (when starting up or when returning from the off mode), but when passing paper, Technologies that make more effective use of electric power have also been proposed.

  However, the number of sheets to be passed (cpm) for one minute at the time of the next image formation after a group of image forming processes (continuous sheet passing print job) in which a plurality of sheets are continuously passed through the nip portion. ) There was a case where it was down, which was a problem. In particular, the image formation conditions (for example, cpm 80 sheets / min) with a recent increase in cpm were remarkable.

JP 2000-315567 A

  The present invention has been made in view of the above-described problems in the prior art. The last sheet of a plurality of sheets output by a single print request is cpm-down in the next print job after exiting the nip portion. An object of the present invention is to provide an image forming apparatus capable of performing proper fixing without any problems.

The inventor verified the details of the above problem, and found that the following problems occurred due to the use of a capacitor during paper feeding and the use of a thin fixing roller.
That is, as shown in FIG. 1, when a large number of sheets are continuously passed, the remaining power amount of the capacitor serving as the auxiliary power source decreases immediately after the start of feeding (points b to c in FIG. 1B). For example, if the paper continues for 60 seconds or more, the remaining power amount is almost lost and the discharge is stopped. After the end of paper passing (after completion of a batch of image forming processes (continuous paper passing print job) in which a plurality of sheets are continuously passed through the nip portion), charging of the capacitor starts but fully charged. Takes some time. Here, even if the capacitor is discharged when it is not charged to the dischargeable voltage V4, the electric power is low, and the fixing roller temperature drop assist is not very effective, so that it is not discharged. Here, when the charging voltage of the capacitor is less than the dischargeable voltage V4 and the charging power is not sufficient (point e in FIG. 1B) (next print job) is received (when the waiting period PA is short). In addition, since there is no heating by the heating means on the capacitor side, and the heat of the fixing roller is taken away by the pressure roller, the temperature drop of the fixing roller after the start of paper feeding increases (point A in FIG. 1A), which is the worst. In the case of cpm, there was a risk of cpm down.
The inventor has found that this problem is affected by the fact that the fixing roller is thin, that the heat capacity of the pressure roller is larger than that of the fixing roller, and that the cpm is larger than the conventional one. As a result of intensive studies, the present invention has been achieved.

  Here, “waiting” means the following from the end of a group of image forming processes (a group of fixing processes performed at the time of the image forming process in the fixing device) performed in response to one print request. The main power supply is turned on until the start of the image forming process (fixing process) (standby period PA), and after all the image forming processes are completed and before shifting to the off mode (waiting period PB). Alternatively, after returning from the off mode and when the fixing member rises (reloads) to the image forming temperature (image reloading process), the image forming process (fixing process) is started (period during which image formation is possible) (standby period PC). Say. A group of image forming processes is a series of processes performed in the image forming apparatus in response to one print request (a signal indicating that a copy start button has been pressed or a print request signal input from a personal computer or the like). (Also called a print job), and there are cases where an image is formed (output) on a single sheet and images are formed (output) by continuously passing a plurality of sheets.

The “off mode” is a state in which the power supply to the heating means is stopped until the next operation (a) or (b) is performed (heating in preparation for returning to the next fixable state). State in which power supply to the means is stopped).
(a) A user presses a power switch (not a main power switch) on the image forming apparatus main body to turn it on.
(b) An external signal such as an image formation start signal is input.

The present invention provided to solve the above problems is as follows.
[1] Image forming apparatus including a fixing device (fixing devices 10 and 60, FIGS. 3, 4, 6, 6, 11, 12, 13, and 14) and a power storage device (auxiliary power supply device 4b) The fixing device includes a rotating fixing member (fixing rollers 14, 24, and 34, a fixing belt 61) and a pressure member (pressure roller 15 and pressure belt) that contact the fixing member to form a nip portion. 62) and heating means (heating elements 2a, 2b, electromagnetic induction heating means (FIGS. 10, 11, 12, 13, 14)) for heating the fixing member, and the image forming apparatus Starts charging the power storage device when the temperature of the pressure member is lower than a threshold temperature after the last sheet of the plurality of sheets output in one print request has exited the nip portion, and the external power supply The fixing member is added by the power of (commercial power supply 4a). The fixing member and the pressure member are rotated while being heated, and the rotation of the fixing member is stopped when the charging voltage of the power storage device exceeds a predetermined voltage from the start of charging of the power storage device. Device (Figure 2) .
[2 ] After the last sheet exits the nip portion, when the temperature of the pressure member is equal to or higher than a threshold temperature, the image forming apparatus stops the rotation of the fixing member and the pressure member, The image forming apparatus according to [1], wherein the power storage device is charged (FIG. 9) .
[3 ] The image forming apparatus according to [ 1 ], wherein the predetermined voltage is a dischargeable voltage of the power storage device .
[4 ] In the image forming apparatus, when the fixing member is heated after the last sheet exits the nip portion, the fixing member is heated to a temperature higher than the temperature of the fixing member being output in response to the print request. The image forming apparatus according to any one of [1] to [3] , wherein the temperature is controlled.
[ 5 ] The image forming apparatus starts charging the power storage device while continuing the rotation of the fixing member and the pressure member after the last sheet exits the nip portion. [1] The image forming apparatus according to any one of [4] .
[6 ] The image forming apparatus according to any one of [1] to [5] , wherein the image forming apparatus supplies power of the power storage device to a device other than the heating unit. Power feeding method (FIG. 16)).
[ 7 ] The image forming apparatus includes a reading device (reading device 130) for reading an image and an automatic document feeder (ADF120), and the power of the power storage device is supplied to at least one of the reading device and the automatic document feeder. The image forming apparatus according to any one of [1] to [5] , wherein the image forming apparatus is supplied (FIGS. 2 and 16).
[ 8 ] The image forming apparatus according to any one of [1] to [7] , wherein a heat capacity of the pressure member is larger than a heat capacity of the fixing member.

As an effect of the present invention, according to the first aspect of the present invention, power is supplied from the external power supply during standby after the last sheet of a plurality of sheets output in one printing request exits the nip portion. The pressure member is warmed by the heat of the fixing member heated by the heating means, and the power storage device (capacitor) is charged to suppress the temperature drop of the fixing member when the capacitor is not fully charged. It is possible to speed up the power supply from the capacitor while preventing the cpm from being reduced, and to prepare for the next print job.
Even when the next print request (print job) is received, the temperature of the fixing member does not drop greatly due to the start of paper feeding, and the power storage device can be charged in such a manner that processing can be performed without cpm down. .
According to the second and third aspects of the present invention, the rotation of the fixing member and the pressure member during standby can be suppressed as much as possible by the temperature of the pressure member, and the life of each member can be extended.
According to the inventions of claims 4 to 7, in the inventions of claims 1 and 3, it is possible to cope with the next print job while improving the efficiency of power.
According to the eighth and ninth aspects of the invention, in the first and third to seventh aspects of the invention, it is possible to cope with the next print job while suppressing the temperature drop of the fixing member and improving the power efficiency. .
According to the inventions of the eleventh and twelfth aspects, even in the indirect power feeding type image forming apparatus, the temperature drop of the fixing member is suppressed in the paper passage when the capacitor charging is not sufficient, and the cpm is prevented from being lowered from the capacitor. The power supply can be advanced and the next print job can be prepared.
According to the thirteenth aspect of the present invention, even when the temperature drop of the fixing member becomes more obvious, it is possible to suppress the temperature drop of the fixing member during paper passing when the capacitor is not sufficiently charged and prevent the cpm from being reduced. Power supply can be accelerated, and the next print job can be prepared.

The configurations of the fixing device and the image forming apparatus according to the present invention will be described below.
FIG. 2 is a cross-sectional view showing a configuration example of the image forming apparatus according to the present invention.
The image forming apparatus 100 includes an automatic document feeder (ADF) 120 that sends a set original to be read to the reading device 130, a reading device 130 that reads the original sent from the ADF 120 as an image, and the reading device 130 reads the original. And an image forming unit 140 that forms an image based on the received image data. The image forming unit 140 includes the fixing device 10 that forms the basis of the present invention.
In FIG. 2, reference numeral 41 denotes a drum-shaped photoconductor which is an example of an image carrier made of a rotating body. Around the photosensitive member 41, a developing device including a charging device 42 composed of a charging roller, a mirror 43 constituting a part of an exposure unit, and a developing roller 44a in the order of rotation in the direction indicated by an arrow in the drawing. 44, a transfer device 48 that transfers the developed image onto a sheet (sheet) as the recording material P, a cleaning device 46 that includes a blade 46a that is in sliding contact with the peripheral surface of the photoreceptor 41, and the like. The photosensitive member 41 is exposed by being scanned with the exposure light Lb via the mirror 43 by the exposure unit between the charging device 42 and the developing roller 44a. The position irradiated with the exposure light Lb on the photoreceptor 41 is referred to as an exposure unit 150.

  The transfer device 48 is provided to face the lower surface of the photoreceptor 41. A portion of the photoconductor 41 facing the transfer device 48 is a transfer unit 47. A pair of registration rollers 49 is provided on the upstream side of the transfer portion 47 in the paper P conveyance direction. The recording material P stored in a paper feed tray (not shown) is fed by a paper feed roller 110 and is transported and guided toward a registration roller 49 by a transport guide (not shown). Further, the fixing device 10 according to the present invention is disposed downstream of the transfer unit 47 in the paper P conveyance direction, and a paper discharge sensor 111 is provided in a paper discharge path on the nip portion output side of the fixing device 10. The paper discharge sensor 111 detects the passage of the last sheet P of the print job through the nip portion and outputs a detection signal. The detection signal can detect the end of printing.

  Image formation in this image forming apparatus is performed as follows. The photosensitive member 41 is rotated by a driving unit (not shown) and starts rotating. During this rotation, the photosensitive member 41 is uniformly charged by the charging device 42 in the dark, and is exposed by the exposure light Lb through the mirror 43 by the exposure unit. By scanning 150, a latent image corresponding to the image to be created is formed on the photoreceptor 41. The latent image on the photoconductor 41 is moved to the developing device 44 by the rotation of the photoconductor 41, where it is developed by the developing device 44 to form a toner image.

  On the other hand, a sheet P as a recording material on the sheet feed tray is fed by the sheet feeding roller 110, and this sheet P is temporarily stopped at the position of the pair of registration rollers 49 through a conveyance path indicated by a broken line in the drawing. It waits for a delivery timing that matches the toner image on the body 41 with the transfer unit 47. At that timing, the registration roller 49 rotates and feeds the paper P, and the paper P is conveyed toward the transfer unit 47. The toner image on the photoconductor 41 and the paper P coincide with each other at the transfer unit 47, and the toner image on the photoconductor 41 is transferred onto the paper P by the electric field generated by the transfer device 48.

In this way, the toner image is transferred and the paper P carrying the toner image is sent out to the fixing device 10. The toner image on the paper P is fixed on the paper P while passing through the fixing device 10, and the paper P on which the toner image is fixed is discharged to a paper discharge unit (not shown).
On the other hand, the residual toner remaining on the photoconductor 41 without being transferred by the transfer unit 47 reaches the cleaning device 46 along with the rotation of the photoconductor 41 and is cleaned while passing through the cleaning device 46 to prepare for the next image formation. .

  As shown in FIG. 3, the fixing device 10 includes a fixing member 14 that is a cylindrical rotating body that is rotatably supported by an axis (axis perpendicular to the paper surface of FIG. 3A) and a pressure member. A member 15 is provided. For example, the fixing member 14 includes a fixing roller (hereinafter referred to as a fixing roller 14) as a heating unit, and the pressure member 15 includes, for example, a pressure member (hereinafter referred to as a pressure roller 15). Inside the fixing roller 14, a heating element 2 that generates heat and heats the fixing roller 14 is disposed. Outside the fixing roller 14, a temperature detection unit 8 a that detects the surface temperature of the central portion of the fixing roller 14, and an end portion of the heating roller 2. Temperature detecting means 8b for detecting the surface temperature is arranged. In addition, a temperature detection means 8 c such as a thermistor for detecting the surface temperature of the pressure roller 15 is disposed outside the pressure roller 15.

The main power supply device 9 supplies power to various units of each part of the image forming apparatus 100 with power from the main power supply 4a (see FIG. 4). The main power supply 9 is supplied with electric power from the commercial power supply 4a by inserting the plug 51 of the power line into the outlet (for example, 100V, 15A) of the commercial power supply 4a that is an external power supply. As shown in FIG. 3, the heating element 2 has a heating element (main heating heater) 2a made of an AC heater, and a heating element (auxiliary heating heater (capacitor heater)) 2b (also called an auxiliary heater) made of a DC heater. For example, a halogen heater is used. The main heating heater 2a includes a main heating heater 2a1 (also referred to as a central heating heater) that mainly heats the central portion in the width direction of the fixing roller 14, and a main heating heater 2a2 (end) that heats the end portion of the fixing roller 14. Also referred to as a partial heater.
However, the auxiliary heater 2b may have a heat generation distribution adjusted in the width direction of the fixing roller 14 (light distribution adjusted). For example, a heater whose light distribution is adjusted so that the heat generation distribution in the central portion of the fixing roller 14 is larger than the end portion, or a heater whose light distribution is adjusted so that the heat generation distribution in the end portion of the fixing roller 14 is larger than the central portion. But you can.

  The sum of the rated power of the central heater 2a1, the fixing power of the end heater 2a2, and the rated power of the auxiliary heater 2b is 80% or more of the maximum power consumption of the AC power source consumed by the image forming apparatus. It is preferable to use a heater with a rated power. In the case of power from an external power source (commercial power source 4a) (in the case of Japan, 1500V of 100V15A), the maximum power consumption of the AC power source consumed by the image forming apparatus is 1500W, so the total rated power of each heater is 1200W or more. Become. Also, the rated power is such that the sum of the rated power of the central heater 2a1, the fixing power of the end heater 2a2, and the rated power of the auxiliary heater 2b is equal to or greater than the maximum power consumption of the AC power source consumed by the image forming apparatus. It is preferable to use a heater. In this case, the total rated power of each heater is 1500 W or more.

  The roller base of the fixing roller 14 is preferably made of a metal such as aluminum or iron from the viewpoint of durability, deformation due to pressure, or the like. The thickness of the roller base at this time is thin because the fixing roller 14 is rapidly heated when the apparatus is started up and reaches a predetermined temperature in a short time, and is preferably less than 5 mm and preferably 1 mm or less. More preferred. For example, it is 0.7 mm. Further, it is desirable to form a release layer on the surface of the fixing roller 14 to prevent the toner from adhering. The inner surface of the fixing roller 14 efficiently absorbs the radiant heat of the heating element 2 that is a halogen heater. It is desirable that the blackening process is performed.

  The pressure roller 15 is formed by forming an elastic layer such as rubber on a core metal, and has a larger heat capacity than the fixing roller 14. The pressure roller 15 is pressed against the fixing roller 14 to form a nip portion, and a recording material P such as paper on which an unfixed image is formed is passed through the nip portion, whereby a toner image is recorded by heat and pressure. Fix on P. Further, a nip portion may be formed between the pressure roller 15 and the fixing roller 14 by using a pressure roller having a foam layer as the pressure roller 15.

  FIG. 4 shows a circuit configuration relating to the heating system of the fixing device 10 of the present invention. In the present embodiment, as shown in FIG. 4, the heating element 2 (2a, 2b) for heating the fixing roller 14 and the charging device 5 capable of supplying power from the commercial power source 4a to the auxiliary power source 4b as a power storage device are provided. . The charging device 5 performs voltage adjustment and AC / DC conversion of power from the commercial power supply 4a, and supplies the auxiliary power supply device 4b with DC power after AC / DC conversion to charge the auxiliary power supply device 4b. The main power switch 6 is controlled by a first control unit as control means for controlling energization to the heating element 2a. The first control unit is supplied with power from the main power supply unit 9 regardless of whether the power switch of the image forming apparatus is turned on or off, and receives a mode signal from the main control unit that controls each part of the image forming apparatus or temperature detection. Based on temperature detection signals from the means 8a and 8b, the main power switch 6 is controlled so that the surface temperature of the fixing roller 14 becomes a set temperature at which fixing is possible.

  The second control unit 3 is supplied with power from the main power supply unit 9 regardless of whether the power switch of the image forming apparatus is on or off, and receives a mode signal from the main control unit and a temperature detection signal from the temperature detection units 8a and 8b. The energization from the auxiliary power supply device 4b to the heating element 2b is controlled based on the output value of the power amount detection means for detecting the power amount (voltage) of the auxiliary power supply device 4b. The charge / discharge switching device 7 connects the auxiliary power supply device 4b to the charging device 5 side based on the mode signal from the main control unit, the temperature detection signals from the temperature detection means 8a and 8b, the output value of the electric energy detection means, and the like. Switching connection is made to the heating element 2b side. When the charge / discharge switching device 7 connects the auxiliary power supply device 4b to the charging device 5 side, the electric power from the commercial power supply 4a is supplied to the auxiliary power supply device 4b after voltage adjustment or AC / DC conversion is performed by the charging device 5. As a result, the auxiliary power supply 4b is charged.

  When the charge / discharge switching device 7 connects the auxiliary power supply device 4b to the heating element 2b side, electric power is supplied from the auxiliary power supply device 4b to the heating element 2b via the second control unit 3. When the main power switch 6 is on, power is supplied from the commercial power supply 4a to the heating element 2a. Examples of the auxiliary power supply device 4b include an electric double layer capacitor (electric double layer capacitor) that can be charged and discharged.

FIG. 5D shows discharge characteristics when an electric double layer capacitor as the auxiliary power supply device 4b is connected to the heating element 2b. The vertical axis V in FIG. 5D indicates the voltage (residual voltage) of the electric double layer capacitor, and the horizontal axis in FIG. 5D indicates time Time. Due to the characteristics of the electric double layer capacitor, the voltage is high at the beginning of discharge, and the voltage decreases with the discharge time (points b to c in FIG. 5D). That is, the electric double layer capacitor has a characteristic that a large amount of power can be supplied in the early stage of discharge, but the supplied power decreases at the end of the discharge. The discharge stop voltage V3 is a voltage at which the electric double layer capacitor has almost no remaining electric power during the discharge process and hardly discharges, and is a voltage at which the auxiliary power supply device 4b stops discharging. The dischargeable voltage V4 is a boundary voltage between a voltage having a power for heating the fixing roller 14 at a discharge start stage and a voltage having no power until the fixing roller 14 is heated, and is equal to or higher than the dischargeable voltage V4. If it is less, the voltage starts discharging, and if it is less, the voltage does not discharge.
Note that the point d (at the end of printing) in FIG. 5D is detected when the last sheet of printing passes through the paper discharge sensor 111, and the auxiliary power supply 4b of the auxiliary power supply 4b is based on the output of the detection signal of the paper discharge sensor 111. Charging starts.

  In this embodiment, the heating of the fixing roller 14 (FIG. 5C) by the heating element 2a to which power is supplied from the commercial power source 4a is used when the paper is passed (after the point b in FIG. 5). The temperature of the fixing roller 14 is maintained by assisting the heating of the fixing roller 14 (FIG. 5D) by a heating element supplied with electric power from the apparatus 4b (FIG. 5A). Instead of the fixing roller 14, an endless belt-like fixing belt and a heating roller having the heating elements 2a and 2b for heating the fixing belt may be combined.

  FIG. 5 shows a case where an image is formed by continuously passing a plurality of sheets as a group of image forming processes (print jobs) corresponding to one print request, and printing associated with the one print request is performed. During the period of the job (points b to d in FIG. 5 (d)), the auxiliary power supply 4b is reduced in the residual voltage to the discharge stop voltage V3 by discharge (point c in FIG. 5 (d)), and thereafter the auxiliary power supply. The power supply from 4b to the heating element 2b is stopped, and the heating element 2b is turned off (points c to d in FIG. 5D).

After the print job is finished (after point d in FIG. 5D), the image forming apparatus 100 is in a standby state (the standby period PA or PB). In this waiting time, the conventional fixing device performs the next standby operation, and is in a state ready for the next print request (the state before the next process).
・ Fixing roller 14: Rotation drive stop (therefore, the pressure roller 15 is also stopped)
Power supply from the commercial power supply 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (eg, 190 ° C.))
Auxiliary power supply 4b; charging

  Immediately after the end of the print job (point d in FIG. 5D), the remaining power amount of the auxiliary power supply 4b is the discharge stop voltage V3, and charging is started from this state. Here, when the remaining print amount of the auxiliary power supply 4b being charged has not yet reached the dischargeable voltage V4, when the next print request (print job) is received, the problem shown in FIG. 1 has occurred. . That is, if a printing request is made at point e in FIG. 1B, the fixing roller 14 is rotated after the electric power is supplied from the commercial power source 4a to the heating element 2a to heat the fixing roller 14 to the fixing target temperature. The paper starts to pass through, but the temperature of the pressure roller 15 decreases between points d to e, and the cooled portion of the pressure roller 15 having a large heat capacity comes into contact with the fixing roller 14 to fix the fixing roller. 14 drastically dropped, and the temperature necessary for fixing was cut in (A portion in FIG. 1A). This is because power is not supplied from the auxiliary power supply device 4b and the heating element 2b is not heated.

  Therefore, in the present invention, the waiting periods PA and PB (between the end of the print job and the start of the next print job) and the waiting period between the end of the print job and the transition to the off mode, The following heating system and fixing roller / pressure roller drive control were devised to solve this problem.

A first embodiment of an image forming apparatus according to the present invention will be described. In the present embodiment, the image forming apparatus 100 starts charging the power storage device (auxiliary power supply device 4b) after the last sheet of the plurality of sheets output by a single print request exits the nip portion of the fixing device 10. The fixing member and the pressure member (pressure roller 15) are rotated while the fixing member (fixing roller 14) is heated by the electric power of the external power source (commercial power source 4a). For example, at the time of standby after the end of a continuous paper print job, the heating system heats the fixing roller 14 with the heating element 2a by the power supplied from the external power source (commercial power source 4a), and the fixing roller 14 is driven to rotate. A standby operation for rotating the pressure roller 15 is performed. That is, at the time of standby, the image forming apparatus 100 performs the next standby operation.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
Auxiliary power supply 4b; charging (not discharging)

  Here, “after the last sheet of a plurality of sheets output by a single print request has exited the nip portion of the fixing device 10” means that the paper discharge sensor 111 detects the passage of the last sheet of the print job. Later. In the standby operation, since the heat of the fixing roller 14 is rotated to transmit the pressure to the pressure roller 15, the pressure roller 15 is not limited to the rotation of the fixing roller 14. What is necessary is just to rotate the pressure roller 15 in contact (the same is true in the following embodiments).

FIG. 6 shows changes in roller temperature in that case. Note that the points up to point d in FIG. 6 are the same as those in FIG.
After the point d (after the point when the last print paper of the previous print job has passed through the fixing exit sensor), the rotating pressure roller 15 is rotated in order to rotate the fixing roller 14 heated by the heating element 2a. Heat is received from the fixing roller 14, and the temperature does not decrease, but the temperature gradually increases. Further, although the fixing roller 14 is deprived of heat by the pressure roller 15, since it is heated by the heating element 2a, it is maintained at a certain temperature (standby control temperature) or higher. When the standby control temperature is controlled to be higher than the temperature of the fixing roller 14 during the paper operation, the heat of the fixing roller 14 can be efficiently transmitted to the pressure roller 15. At this time, at least the auxiliary power supply 4b is not discharged.

  It should be noted that the present invention may be applied when the remaining power amount of the auxiliary power supply 4b is somewhat reduced by a continuous paper-passing print job executed before the standby time. It is preferable to apply when the remaining power amount of the auxiliary power supply 4b is greatly reduced by the job and is less than the dischargeable voltage V4 by charging. For example, the standby operation may be performed when the charging voltage of the power storage device (auxiliary power supply device 4b) at the end of the continuous paper passing print job is equal to or lower than the dischargeable voltage V4.

  In addition, the rotation of the fixing roller 14 is performed at a temperature T1 (assuming that the temperature of the pressure roller 15 detected by the temperature detecting unit 8c decreases less than the temperature of the fixing roller 14 even if the sheet passing is started (temporarily 80 ° C., FIG. It is good to carry out until it reaches (C point of 6). Then (after the point e in FIG. 6), the normal standby operation described above is performed.

  According to the above standby operation, when the next print request (print job) is received, the fixing is performed by starting the sheet passing even when the remaining power amount of the auxiliary power supply device 4b has not yet reached the dischargeable voltage V4. The temperature of the roller 14 does not drop greatly, and processing can be performed without cpm down.

Next, a second embodiment of the fixing device according to the present invention will be described. In this embodiment, after the last sheet exits the nip portion of the fixing device 10, when the residual voltage of the auxiliary power supply 4 b is equal to or lower than the dischargeable voltage V4, the image forming apparatus 100 charges the auxiliary power supply 4 b. The fixing roller 14 and the pressure roller 15 are rotated while the fixing roller 14 is heated by the electric power of the commercial power source 4a. That is, at the time of standby, the image forming apparatus 100 performs the next standby operation.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
Auxiliary power supply 4b; charging

FIG. 7 shows changes in the roller temperature and the remaining power amount of the auxiliary power supply in that case. The change in roller temperature in FIG. 7A is the same as that in FIG.
After the point d (after the point when the last print paper of the previous print job has passed through the fixing exit sensor), the rotating pressure roller 15 is rotated in order to rotate the fixing roller 14 heated by the heating element 2a. Heat is received from the fixing roller 14, and the temperature does not decrease, but the temperature gradually increases. Further, although the fixing roller 14 is deprived of heat by the pressure roller 15, since it is heated by the heating element 2a, it is maintained at a certain temperature (standby control temperature) or higher. When the standby control temperature is controlled to be higher than the temperature of the fixing roller 14 during the paper operation, the heat of the fixing roller 14 can be efficiently transmitted to the pressure roller 15. Regarding the rotation driving of the fixing roller 14, for example, when the last print sheet of the previous print job passes through the fixing exit sensor, the remaining power amount (capacitor voltage) of the auxiliary power supply 4 b is confirmed, and the dischargeable voltage V 4 (temporarily 28 v) or less. In this case, the rotation of the fixing roller 14 that has been rotationally driven in the previous print job may be continuously rotated without being stopped.

  At this time, the auxiliary power supply 4b is charged at the same time (after point d in FIG. 7B). As the rotation time of the fixing roller, when charging the auxiliary power supply 4b, a charging time sufficient to be equal to or higher than the dischargeable voltage V4, for example, 15 seconds is set as the upper limit time, and the rotation time may be rotated during this time. . Alternatively, when the charging voltage reaches the dischargeable voltage V4, the fixing roller 14 stops rotating and charging is continued. Alternatively, even if the temperature of the pressure roller 15 detected by the temperature detection means 8c is the temperature T1 at which the temperature drop of the fixing roller 14 is reduced even if the sheet feeding is started (temporarily at 80 ° C., point C in FIG. 7A). It is good to do until it reaches. After that (after point e in FIG. 7), the normal standby operation described above is performed.

  According to the above standby operation, even when the next print request (print job) is received, the temperature of the fixing roller 14 does not drop greatly due to the start of paper passing, and the processing can be performed without cpm down. The auxiliary power supply 4b can be charged.

When the remaining voltage of the auxiliary power supply 4b exceeds the dischargeable voltage V4 after the last sheet has exited the nip portion of the fixing device 10, the image forming apparatus 100 rotates the fixing roller 14 and the pressure roller 15. May be stopped and charging of the auxiliary power supply 4b may be started.
As described above, when the charging voltage of the power storage device (capacitor) is lower than the dischargeable voltage V4 at the end of the continuous paper passing print job, the fixing member heated by the heating means supplied with power from the external power supply during standby is used. By rotating and raising the temperature of the pressure member, it is possible to suppress the temperature drop of the fixing member with respect to printing when the capacitor power is insufficient (during the next print job), and to prevent cpm down. If the fixing member is thin, the temperature drop will be large, so it should be rotated each time it is in standby, but this will affect the life of the fixing member and the pressure member. While avoiding the problem with respect to the service life, it is possible to prevent a drop in temperature in the case of paper passing after continuous paper passing.
Further, when the charge voltage of the power storage device (capacitor) is exceeded at the end of the continuous paper-passing print job and exceeds the dischargeable voltage V4, the next print job can be handled by a normal standby operation.

Next, a third embodiment of the fixing device according to the present invention will be described. In the present embodiment, after the last sheet has exited the nip portion of the fixing device 10, the heating system does not supply power to the heating elements 2 a and 2 b and does not heat the fixing roller 14. The device 4b) is charged quickly. That is, at the time of standby, the image forming apparatus 100 performs the next standby operation.
・ Fixing roller 14: Rotation drive stop (therefore, the pressure roller 15 is also stopped)
-Power supply from the commercial power supply 4a to the heating element 2a; OFF-Auxiliary power supply device 4b; Rapid charging

FIG. 8 shows a change in the remaining power amount of the auxiliary power supply device.
First, after the point d in FIG. 8A (after the last print sheet of the previous print job passes through the fixing exit sensor), when the remaining power amount of the auxiliary power supply 4b is equal to or lower than the dischargeable voltage V4, the commercial power supply 4a So that the power supply to the heating element 2a is turned off and the heating element 2a is turned off.
As a method of turning off the power supply from the commercial power supply 4a to the heating element 2a, the power supply is forcibly stopped or the control temperature of the fixing roller 14 is fixed from the normal set temperature during charging of the auxiliary power supply 4b. The temperature is set to be lowered to a temperature at which the temperature of the roller 14 does not drop. Here, the control temperature of the fixing roller 14 is a set temperature at which the heating roller 2a controls the heating of the fixing roller 14 so that the temperature detected by the temperature detecting means 8a and 8b becomes the control temperature. When the temperature falls below the control temperature, power is supplied from the commercial power supply 4a to the heating element 2a, and when the control temperature exceeds the control temperature, the power supply is stopped. Here, for example, the normal standby control temperature (190 ° C.) is lowered to the quick charge control temperature (170 ° C.).

  Thereby, since the power consumption of the heating element 2a is eliminated, the surplus power can be used for the charging power of the auxiliary power supply device 4b. Therefore, as shown in FIG. 8 (b), the auxiliary power supply 4b can be rapidly charged by the charging power (200W) obtained by adding the surplus power (100W) to the normal charging power (for example, 100W), and the time of the operation It can be shortened.

  Next, a fourth embodiment of the fixing device according to the present invention will be described. In the present embodiment, in the image forming apparatus 100, after the last sheet exits the nip portion of the fixing device 10, the following standby operations (a) and (b) are performed based on the detected temperature of the pressure roller 15. Either one is selected and executed.

Standby operation (a): The heating system heats the fixing roller 14 with the power supplied from the external power source (commercial power source 4a), charges the power storage device (auxiliary power source device 4b), and rotates the fixing roller 14 Rotate the pressure roller 15 together.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
Auxiliary power supply 4b; charging

Standby operation (b): The heating system performs rapid charging of the power storage device (auxiliary power supply device 4b) without supplying power to the heating elements 2a and 2b and without heating the fixing roller 14.
・ Fixing roller 14: Rotation drive stop (therefore, the pressure roller 15 is also stopped)
-Power supply from the commercial power supply 4a to the heating element 2a; OFF-Auxiliary power supply device 4b; Rapid charging

  In the present embodiment, even when the temperature of the pressure roller 15 detected by the temperature detection unit 8c at the end of a continuous sheet-passing print job is less than the temperature T1 at which the temperature drop of the fixing roller 14 decreases even if the sheet passing is started. For example, the standby operation (a) is executed, and the operation is switched so that the standby operation (b) is executed if the temperature is equal to or higher than the temperature T1.

  FIG. 9 shows an example of changes in roller temperature in this embodiment. In this case, since the temperature of the pressure roller 15 is equal to or higher than the temperature T1 at the end of the continuous sheet (time 80 s) print job, the standby operation for quickly charging the auxiliary power supply 4b without supplying power to the heating element 2a ( b) is executed.

  According to the above standby operation, even when the next print request (print job) is received, the temperature of the fixing roller 14 does not drop greatly due to the start of paper passing, and the processing can be performed without cpm down. The auxiliary power supply 4b can be charged. The temperature of the pressure roller 15 can suppress the rotation of the fixing roller 14 and the pressure roller 15 during standby as much as possible, thereby extending the roller life.

  In the above embodiment, a case where a heating element such as a halogen heater is used for the heating system of the fixing roller 14 is shown. However, the present invention is not limited to this, and heating means based on an electromagnetic induction system as shown below. It is good.

(Electromagnetic induction heating means 1)
FIG. 10 shows a configuration of a fixing device and its peripheral circuits in another embodiment of the image forming apparatus according to the present invention. In this embodiment, electromagnetic induction heating means is used instead of the heating element 2 in FIG. A fixing device 10 according to this embodiment shown in FIG. 10A has a thin fixing roller 14 having a Ni thin layer as a heat generating layer under the release layer, and the fixing roller 14 has electromagnetic induction heating means. An induction heating coil 12a as a heat generating member for the main power supply (commercial power supply 4a) and an induction heating coil 12b as a heat generating member for the auxiliary power supply 4b are arranged. Further, the fixing device 10 includes inverter circuits 16a and 16b that flow alternating currents (high-frequency currents) to the induction heating coils 12a and 12b, a rectifier circuit 17a that rectifies an AC voltage from the commercial power supply 4a, and an auxiliary power supply device 4b. A DC / DC converter 17b that transforms the voltage is included.

  The AC voltage from the commercial power supply 4a is rectified by the rectifier circuit 17a and converted to a high frequency by the inverter circuit 16a. The induction heating coil 12a is supplied with a high-frequency current from the inverter circuit 16a to generate a magnetic flux. By this magnetic flux, an eddy current flows to the heat generating layer of the fixing roller 14 and is converted into Joule heat by the skin resistance of the fixing roller 14. As a result, the fixing roller 14 is heated.

  The auxiliary power supply device 4b includes an electric double layer capacitor and a charger that charges the electric double layer capacitor with electric power from the commercial power supply 4a. The direct current output of the auxiliary power supply device 4b is transformed by the DC / DC converter 17b, converted to a high-frequency current by the inverter circuit 16b and sent to the induction heating coil 12b, and eddy current is generated by the magnetic flux generated by the induction heating coil 12b. Flows into the heat generating layer of the fixing roller 14 and is converted into Joule heat by the skin resistance of the fixing roller 14, whereby the fixing roller 14 is heated. The recording paper P passes between the fixing roller 14 and the pressure roller 15, and the recording paper P melts and melts as a result of heating and pressurization by the fixing roller 14 and the pressure roller 15 generated by the Joule heat. To wear.

  In the fixing device of this embodiment, the DC / DC converter 17b, which is a power adjustment means, is controlled in the same manner as in the above-described embodiment, and the auxiliary power supply device 4b changes from the auxiliary power supply device 4b to the induction heating coil 12b in response to start-up, paper feeding and standby. Appropriate supply power can be supplied.

Alternatively, the fixing roller 14 may be heated by superimposing the power of the auxiliary power supply 4b on the power of the commercial power supply 4a and supplying it to the induction heating coil 12a. The circuit configuration in that case is shown in FIG. The direct-current power of the auxiliary power supply 4b is superimposed on the output of the rectifier circuit 17a on the commercial power supply 4a side via the DC / DC converter 17b and input to the high-frequency inverter 16a. And is fed to the induction heating coil 12a to heat the fixing roller 14. Since there is only one induction heating coil, there is no problem of interference noise or mutual induction due to the frequency difference between the high frequency currents of the induction heating coils 12a and 12b generated in the configuration of FIG. Can be provided.
Even in the fixing device configured as described above, the first to fourth embodiments of the image forming apparatus according to the present invention described above can be applied.

(Electromagnetic induction heating means 2)
FIG. 11 and FIG. 12 show a configuration example in which the fixing device 10 in the image forming apparatus 100 of the present invention is provided with an induction-type external heating means by electromagnetic induction.
The fixing device 10 includes a fixing roller 24, a pressure roller 15 as a pressure rotating body that forms a fixing nip portion between the fixing roller 24, and an induction-type external heating unit 52 using electromagnetic induction. Yes.
The external heating means 52 includes a coil holder 54 and a coil 56 made of a conductive wire wound around the coil holder 54. The coil holder 54 is supported by a device side plate (not shown). The external heating unit 52 has a length of about 70 mm in the circumferential direction of the fixing roller 24, and extends over substantially the entire axial direction of the fixing roller 24.
Further, a thermopile 35 as temperature detecting means for detecting the surface temperature of the fixing roller 24, a thermistor 36 as temperature detecting means for detecting the surface temperature of the pressure roller 15, and detection information of the thermopile 35 and the thermistor 36. Control means 40 for controlling power supply to the coil 56 is provided. The control means 40 means a microcomputer including a CPU, ROM, RAM, I / O interface and the like.

  In the present embodiment, the fixing roller 24 has an outer diameter of 50 mm, a sleeve-shaped metal core 24a as a core material, and a radial outer side of the roller (a direction from the center toward the outer periphery) on the metal core 24a. A heat insulating layer 24b, a heat generating layer 24c, an elastic layer 24d, and a release layer 24e are sequentially provided. The metal core 24a prevents the roller from being bent, and is preferably made of a metal such as aluminum or iron having a thickness of 2 to 3 mm from the viewpoint of strength and heat resistance. Since there is no heat source inside, the thermal conductivity is not relevant, and it may be resin, glass or ceramic. Further, the wall thickness can be appropriately changed depending on the configuration such as the load, and is not limited to 2 to 3 mm.

The heat insulating layer 24b is a layer for suppressing heat transfer from the heat generating layer 24c to the cored bar 24a, and is formed of a foamed silicone rubber having a JIS A hardness of 5 to 50 to a thickness of 4 mm. The heat insulating layer 24b may be made of a material other than foamed silicone rubber. For example, the heat resistant elastomeric material may be fluororubber.
The heat generating layer 24c is formed as a metal layer having a thickness of 0.05 to 0.5 mm. The heat generation layer 24c for induction heat generation may be a non-magnetic metal, but is made of a ferromagnetic material such as magnetic stainless steel such as SUS430 and SUS410, iron and nickel, and an alloy containing these as main components. Desirably, the elastic layer 24d is made of a heat-resistant elastomer such as silicone rubber or fluororubber, and has a thickness of 0.25 mm. The elastic layer 24d is provided from the viewpoint of obtaining flexibility that can follow the unevenness of the paper P or toner image. Since the elastic layer 24d exists on the heat generating layer 24c, it is desirable that the heat of the heat generating layer 24c be easily transferred to the surface. From this viewpoint, in order to increase the thermal conductivity, various fillers such as metals are mixed. Good. The range of the thickness of the elastic layer 24d is 0.2 mm to 2 mm. By following the unevenness of the image surface due to the toner particle diameter of 10 μm or less and the paper fiber having a thickness of around 10 μm, etc., it suppresses uneven gloss due to variations in the amount of heat transferred from the fixing roller 24 to the toner, This is to obtain a high-quality fixing image quality. More preferably, it is 100 μm or more. The hardness is desirably a JISA hardness of 30 degrees or less.
The release layer 24e is provided so as to ensure release properties without applying oil to the surface of the fixing roller 24, and has a release property such as fluorine resin such as PFA or PTFE, or release properties. It is formed into a layer having a thickness of 10 to 80 μm by silicone resin or rubber. The durability of the fixing roller 24 can be improved by forming it with a fluorine-based resin such as PFA or PTFE that is less likely to be worn and scratched than silicone rubber.

The pressure roller 15 as the pressure rotator is the same as that shown in FIG. 3, and is pressed against the fixing roller 24 by an urging means (not shown).
In FIG. 10, the fixing roller 24 is configured to be softer than the surface hardness of the pressure roller 15. For this reason, as shown in the drawing, the fixing nip portion is configured such that the pressure roller 15 enters the fixing roller 24 and the elastic layer 24d and the heat insulating layer 24b are deformed. As a result, the sheet P is bent so as to be convex with respect to the fixing roller 24 at the fixing nip portion SN, and the separation from the fixing roller 24 after fixing is improved. In FIG. 10, the SN indicates a portion where the fixing roller is recessed by the pressure roller.
The fixing roller 24 is driven by a motor (not shown) and a transmission gear, and rotates the pressure roller 15 by being driven.

  In this heating method, a high frequency magnetic field is generated by driving the coil 56 provided in the external heating means 52 with a high frequency by the induction heating inverter circuit 50, and an eddy current flows through the heat generating layer 24c of the fixing roller 24 by this magnetic field. Thus, the temperature of the fixing roller 24 is increased. For example, when a high frequency current of about 20 to 60 kHz is passed through the coil 56, an eddy current is generated in the heat generating layer 24c of the fixing roller 24, and the heat generating layer 24c is heated by Joule heat. The induction heat can raise the surface temperature of the fixing roller 24 to a temperature at which the toner melts. By this induction heating method, the heat generating layer 24c near the surface layer of the fixing roller 24 can be directly heated, and the rise time can be shortened.

Here, the induction heating inverter circuit 50 has, for example, a parallel resonance circuit in which a coil 56 and a capacitor are connected in parallel, and a DC current obtained by rectifying the AC from the commercial power supply 4a is supplied to the parallel resonance circuit. It has come to be. The induction heating inverter circuit 50 has a switching element, and may be of a type that supplies a high-frequency current to the parallel resonance circuit by driving the switching element at a high frequency. In the present embodiment, the direct current from the auxiliary power supply device 4b can be added to the direct current obtained by rectifying the alternating current from the commercial power supply 4a. As a result, when the apparatus is started up or in the standby mode (except when a print job is performed), the external heating unit 52 is driven only by supplying power from the commercial power supply 4a to heat the fixing roller 24, and the print job. When performing the above, the external heating means 52 is driven by heating the fixing roller 24 by superimposing the power from the auxiliary power supply 4b on the power from the commercial power supply 4a and supplying the power.
Even in the fixing device having such a configuration, the first to fourth embodiments of the image forming apparatus according to the present invention described above can be applied.

(Electromagnetic induction heating means 3)
Instead of the electromagnetic induction type external heating means of FIG. 11, an electromagnetic induction type heating means may be provided inside the fixing roller. FIG. 13 shows a configuration example in which the fixing device 10 in the image forming apparatus 100 of the present invention is provided with an induction-type internal heating means by electromagnetic induction.
The fixing device 10 is disposed inside a cylinder of the fixing roller 34, a thin fixing roller 34 having a heat generation layer, a pressure roller 15 as a pressure rotating body that forms a fixing nip portion between the fixing roller 34, and the fixing roller 34. In addition, an electromagnetic induction type internal heating means including an induction coil 22, a magnetic core 21, and a magnetic flux shielding plate 23 is provided. The induction coil 22 is connected to the induction heating inverter circuit 50, the commercial power supply 4a, and the auxiliary power supply device 4b with the same configuration as the electromagnetic induction heating means 2 described above.

With this configuration, the induction coil 22 provided in the internal heating means is driven at a high frequency by the induction heating inverter circuit 50 to generate a high frequency magnetic field, and the magnetic field causes the eddy current to flow in the heat generating layer of the fixing roller 34 to fix. The temperature of the roller 34 can be raised. In addition, a direct current from the auxiliary power supply 4b can be added to a direct current obtained by rectifying the alternating current from the commercial power supply 4a. When not performing, the internal heating means is driven only by supplying power from the commercial power supply 4a to heat the fixing roller 34, and when performing a print job, the power from the commercial power supply 4a is supplied to the power from the auxiliary power supply 4b. By supplying electric power with superposition of electric power, the internal heating means is driven to heat the fixing roller 34. The magnetic flux shielding plate 23 is made of a conductive material and has a function of shielding the magnetic flux generated in the induction coil 22. The magnetic flux shielding plate 23 is a predetermined region (non-sheet passing portion region) in the width direction of the fixing roller 34 and is the induction coil 22. / By inserting the magnetic flux shielding plate 23 between the magnetic core 21 and the fixing roller 34, it is possible to suppress the temperature rise in the non-sheet passing portion region of the fixing roller 34.
Even in the fixing device having such a configuration, the first to fourth embodiments of the image forming apparatus according to the present invention described above can be applied.

(Electromagnetic induction heating means 4)
FIG. 14 is a configuration diagram of a fixing device in an image forming apparatus according to the present invention of a fixing belt type using electromagnetic induction type heating means.
The fixing device 60 includes a fixing belt 61 that heats the toner image on the sheet P, and a heat pipe 65 that is disposed inside the fixing belt 61 and reduces a temperature distribution difference in the longitudinal direction of the fixing belt 61. A flange is provided at the end of the heat pipe 65 in the longitudinal direction with a gap, and covers the end of the heat pipe 65 in the longitudinal direction.

  The fixing device 60 includes a fixing belt 61 that is maintained at a high temperature and contacts the toner image transfer surface of the sheet P, and a pressure belt 62 that contacts the back surface of the sheet P and pressurizes the sheet P between the fixing belt 61 and the fixing belt 61. It has. The fixing belt 61 and the pressure belt 62 are assembled so as to be capable of being pressed / separated, and circulate in an interlocked state when the sheet P passes, but are separated during the standby of the sheet P and circulate individually. doing.

  The heating unit of the present embodiment includes a coil unit 78 as a magnetic flux generating unit and a fixing belt 61 as a heat generating member that generates heat by induction with the magnetic flux from the coil unit 78. Further, a fixing roller 63 and a fixing tension roller 64 are provided as suspension members that are wound around the fixing belt 61 and stretch the fixing belt 61 with a predetermined tension.

  The coil unit 78 includes an exciting coil that generates a magnetic flux when energized, a magnetic core that collects the generated magnetic flux, an excitation coil, a holder that supports the magnetic core, and the like.

  The fixing belt 61 is an endless belt stretched between a fixing roller 63 that rotationally drives the fixing belt 61 and a fixing tension roller 64 as a suspension member for suspension and heat sources.

  The fixing belt 61 is made of nickel having a thickness of 75 μm as a base layer, and a 300 μm elastic layer is provided on the outer periphery of the base layer. Silicone rubber is used as the material of the elastic layer, the hardness is JIS-A 20 degrees, and the thermal conductivity is 0.8 W / mK. At the exit of the nip between the fixing belt 61 and the pressure belt 62, the elastic layer is deformed, so that the sheet P is well separated from the belt, and the winding of the sheet P around the fixing belt 61 is prevented. On the outer periphery of the elastic layer, a fluororesin layer (for example, PFA or PTFE) is provided with a thickness of 30 μm as a surface release layer.

  The pressure belt 62 is made of Ni having a thickness of 75 μm as a base layer, and an elastic layer having a thickness of 300 μm is provided on the outer periphery of the base layer. On the surface of the elastic layer of the pressure belt 62, a fluororesin layer (PFA) having a thickness of 30 μm is provided as a release layer.

  The fixing tension roller 64 has a single heat pipe 65 inserted therein as a heat transfer means inside an iron hollow roller 64a. The pipe material of the heat pipe 65 is copper, and a small amount of pure water is sealed inside as a heat medium. Further, the fixing tension roller 64 is assembled by urging both ends of the rotation shaft outward with springs (not shown), and also has a function as a tension roller that applies tension to the fixing belt 61.

  The fixing roller 63 is rotationally driven by a drive mechanism (motor and drive gear train) (not shown). The fixing roller 63 is an elastic roller in which a silicone rubber layer 63a as an elastic layer is provided on the surface of a core metal 63b of an iron-based alloy. By providing the silicone rubber layer 63 a on the fixing roller 63, a frictional transmission force is generated between the fixing roller 61 and the fixing belt 61, so that the fixing belt 61 can be rotated well following the rotation of the fixing roller 63.

  Further, by pressing the pressure roller 67 against the fixing roller 63 and deforming the flexible silicone rubber layer 63a, a nip outlet that ensures separation of the sheet from the fixing belt 61 is formed. The pressure roller 67 is a ferrous alloy roller having an outer diameter of 23 mm and an inner diameter of 20 mm. The halogen heater 68 is disposed on the central axis and rotates outside the halogen heater 68.

  A fixing pad 66 disposed on the upstream side of the fixing roller 63 along the fixing belt 61 pushes the fixing belt 61 from the inside to contact and pressurize the pressure belt 62. The fixing pad 66 has a rigid body made of a SUS drawing material as a mandrel, and the surface thereof is covered with a sliding sheet to reduce sliding resistance when rubbing against the fixing belt 61. The sliding sheet is a sheet material obtained by coating a nonwoven fabric made of glass fiber with a fluororesin.

  The pressure belt 62 is stretched between a pressure roller 67 and a pressure tension roller 70. The pressure tension roller 70 is made of an iron alloy having an outer diameter of 20 mm and an inner diameter of 16 mm.

  The elastic pressure pad 71 is disposed on the inner side of the pressure belt 62 and upstream of the pressure roller 67, and forms a predetermined circulation path in the pressure belt 62 to fix the pressure belt 62 to the fixing belt 61. Pressurize toward

  A fixing nip formed by the fixing pad 66 and the pressure pad 71 extends to about 18 mm in the conveying direction, and contributes to speeding up image formation by supplying predetermined fixing energy to the sheet P in a short time. To do.

  The fixing roller 63 and the pressure roller 67 are given driving force by a driving motor (not shown), and rotate at a predetermined peripheral speed of 210 mm / s during the fixing operation. A circumferential speed difference is given to the fixing roller 63 and the pressure roller 67. The difference is 210% / s of the fixing roller 63, and the pressure roller 67 is plus 3%.

  In the present embodiment, the use of a thin endless belt on both the fixing side and the pressure side as a member that is in contact with the sheet P and is involved in fixing achieves a lower heat capacity in a portion that needs to be kept at a higher temperature than before. . As a result, it contributes to shortening the warm-up time (the time required from when the color electrophotographic printer 100 is turned on until it can be fixed).

  In the fixing device 60 configured as described above, a sheet having an unfixed toner image at the fixing nip between the fixing belt 61 and the pressure belt 62 in a state where the fixing belt 61 rises to a predetermined fixing temperature and is temperature-controlled. P is conveyed. The sheet P is introduced with the surface carrying the unfixed toner image facing the fixing belt 61 side. Then, the unfixed toner image on the sheet P is nipped and conveyed while being in close contact with the outer peripheral surface of the fixing belt 61, so that heat is mainly applied from the fixing belt 61, and the unfixed toner is received under pressure. The image is fixed on the surface of the sheet P.

The coil unit 78 is connected to the induction heating inverter circuit 50, the commercial power supply 4 a, and the auxiliary power supply device 4 b with the same configuration as the electromagnetic induction heating unit 2 described above. With this configuration, the induction coil provided in the coil unit 78 is driven at high frequency by the induction heating inverter circuit 50 to generate a high frequency magnetic field, and this magnetic field causes an eddy current to flow in the Ni base layer of the fixing belt 61, thereby fixing belt. The temperature of 61 can be raised. In addition, a direct current from the auxiliary power supply 4b can be added to a direct current obtained by rectifying the alternating current from the commercial power supply 4a. When not performing, the coil unit 78 is driven only by supplying power from the commercial power source 4a to heat the fixing belt 61, and when performing a print job, the power from the commercial power source 4a is supplied to the power from the auxiliary power source 4b. By supplying electric power with superposition of electric power, the coil unit 78 is driven to heat the fixing belt 61.
Even in the fixing device having such a configuration, the first to fourth embodiments of the image forming apparatus according to the present invention described above can be applied.

Further, in the present invention so far, the case of the direct power supply method in which the power of the auxiliary power supply device 4b is supplied to the heating means when the sheet is passed through the nip portion for fixing is shown. That is, as shown in FIG. 15, a part of the electric power of the commercial power supply 4a is supplied to the heating element 2a when passing paper, and the rest is a system such as a drive system (motor) and a scanner (reading light source) in the image forming apparatus. While supplying to the system | strain 101, it is the structure which supplies the electric power of the auxiliary power supply device 4b to the heat generating body 2b.
The present invention is not limited to this direct power supply method. For example, when fixing is performed by passing a sheet through the nip portion, the power of the auxiliary power supply 4b is used as power for driving other devices of the fixing device (for example, a roller). It is also possible to supply the electric power of the external power source (commercial power source 4a) with a surplus to the heating means. Alternatively, when the image forming apparatus is viewed as a whole, when an image is formed by passing a sheet through the nip portion, the power of the auxiliary power supply 4b is used as the power for driving a device other than the fixing device (for example, the automatic document feeder in FIG. 2). (ADF) 120 and driving power of the reading device 130), and the power of the external power source (commercial power source 4a) that has a surplus by that amount may be supplied to the heating means.
In the fixing device in these cases, the first to fourth embodiments of the image forming apparatus according to the present invention described above can be applied.

That is, the invention corresponding to the first embodiment of the image forming apparatus according to the present invention described above is the same as that of the image forming apparatus having the configuration of FIG. 2, as shown in FIG. Has a configuration of an indirect power supply system that is supplied to a system system 101 such as a drive system (motor) and a scanner (reading light source). That is, the image forming apparatus according to the present embodiment includes a fixing roller 14, a pressure roller 15 that presses the fixing roller 14 rotatably and forms a nip portion that fixes unfixed toner on the sheet, and the fixing roller 14. A fixing device 10 having a heating means (heating element 2a) for heating the sheet and an auxiliary power supply device 4b, and the power of the auxiliary power supply device 4b other than the heater is used when an image is formed by passing a sheet through the nip portion. Used as power for the apparatus (system system 101), surplus power for the auxiliary power supply 4b in the external power supply (commercial power supply 4a) is supplied to the heating element 2a in addition to the normal supply power from the external power supply. In the case of the configuration (FIG. 16B), the image forming apparatus 100, after the last sheet of the plurality of sheets output by a single print request exits the nip portion of the fixing device 10, The fixing member and the pressure member (pressure roller 15) are rotated while the fixing member (fixing roller 14) is heated by the electric power of the external power source (commercial power source 4a) without discharging the electric device (auxiliary power supply device 4b). The standby operation is performed. That is, at the time of standby, the fixing device 10 and the auxiliary power supply device 4b perform the following standby operation.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
-Auxiliary power supply 4b; no discharge

Here, it is preferable that the standby operation is performed when the charging voltage of the power storage device (auxiliary power supply device 4b) at the end of the continuous sheet passing print job is equal to or lower than the dischargeable voltage V4 during the standby time. FIG. 7).
The heating element 2b may be used as a sub heater supplied with power from the commercial power source 4a or may be omitted.

The invention corresponding to the second embodiment of the image forming apparatus according to the present invention described above is the same as that of the image forming apparatus having the configuration of FIG. 2, as shown in FIG. Has a configuration of an indirect power supply system that is supplied to a system system 101 such as a drive system (motor) and a scanner (reading light source). That is, the image forming apparatus according to the present embodiment includes a fixing roller 14, a pressure roller 15 that presses the fixing roller 14 rotatably and forms a nip portion that fixes unfixed toner on the sheet, and the fixing roller 14. A fixing device 10 having a heating means (heating element 2a) for heating the sheet and an auxiliary power supply device 4b, and the power of the auxiliary power supply device 4b other than the heater is used when an image is formed by passing a sheet through the nip portion. Used as power for the apparatus (system system 101), surplus power for the auxiliary power supply 4b in the external power supply (commercial power supply 4a) is supplied to the heating element 2a in addition to the normal supply power from the external power supply. In the case of the configuration (FIG. 16B), the image forming apparatus 100, after the last sheet of the plurality of sheets output by a single print request exits the nip portion of the fixing device 10, Charging of the electric device (auxiliary power supply device 4b) is started, and the fixing member and the pressure member (pressure roller 15) are rotated while the fixing member (fixing roller 14) is heated by the electric power of the external power source (commercial power supply 4a). The standby operation is performed. That is, at the time of standby, the fixing device 10 and the auxiliary power supply device 4b perform the following standby operation.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
Auxiliary power supply 4b; charging

Further, the invention corresponding to the above-described third embodiment of the image forming apparatus according to the present invention is the image forming apparatus having the configuration of FIG. 2, as shown in FIG. Has a configuration of an indirect power supply system that is supplied to a system system 101 such as a drive system (motor) and a scanner (reading light source). That is, the image forming apparatus according to the present embodiment includes a fixing roller 14, a pressure roller 15 that presses the fixing roller 14 rotatably and forms a nip portion that fixes unfixed toner on the sheet, and the fixing roller 14. A fixing device 10 having a heating means (heating element 2a) for heating the sheet and an auxiliary power supply device 4b, and the power of the auxiliary power supply device 4b other than the heater is used when an image is formed by passing a sheet through the nip portion. Used as power for the apparatus (system system 101), surplus power for the auxiliary power supply 4b in the external power supply (commercial power supply 4a) is supplied to the heating element 2a in addition to the normal supply power from the external power supply. In the case of the configuration (FIG. 16B), after the last sheet exits the nip portion of the fixing device 10, the heating system does not supply power to the heating element 2a and the fixing roller 14 And it performs rapid charging of the power storage device without heat (auxiliary power unit 4b). That is, at the time of standby, the fixing device 10 and the auxiliary power supply device 4b perform the following standby operation.
・ Fixing roller 14: Rotation drive stop (therefore, the pressure roller 15 is also stopped)
-Power supply from the commercial power supply 4a to the heating element 2a; OFF-Auxiliary power supply device 4b; Rapid charging

  The invention corresponding to the above-described fourth embodiment of the image forming apparatus according to the present invention is the same as that of the image forming apparatus having the configuration shown in FIG. Has a configuration of an indirect power supply system that is supplied to a system system 101 such as a drive system (motor) and a scanner (reading light source). That is, the image forming apparatus according to the present embodiment includes a fixing roller 14, a pressure roller 15 that presses the fixing roller 14 rotatably and forms a nip portion that fixes unfixed toner on the sheet, and the fixing roller 14. A fixing device 10 having a heating means (heating element 2a) for heating the sheet and an auxiliary power supply device 4b, and the power of the auxiliary power supply device 4b other than the heater is used when an image is formed by passing a sheet through the nip portion. Used as power for the apparatus (system system 101), surplus power for the auxiliary power supply 4b in the external power supply (commercial power supply 4a) is supplied to the heating element 2a in addition to the normal supply power from the external power supply. In the case of the configuration (FIG. 16B), after the last sheet exits the nip portion of the fixing device 10, the following standby operation (c), based on the detected temperature of the pressure roller 15, In which one of d) is selected and executed.

Standby operation (c): The heating system heats the fixing roller 14 with the power supplied from the external power source (commercial power source 4a), charges the power storage device (auxiliary power source device 4b), and drives the fixing roller 14 to rotate. Rotate the pressure roller 15 together.
Fixing roller 14: Rotation drive (therefore, the pressure roller 15 is also rotated)
Power supply from the commercial power source 4a to the heating element 2a: ON (the fixing roller 14 is kept at a predetermined temperature (standby control temperature, for example, 190 ° C.))
Auxiliary power supply 4b; charging

Standby operation (d): The heating system performs rapid charging of the power storage device (auxiliary power supply device 4b) without supplying power to the heating element 2a and without heating the fixing roller 14.
・ Fixing roller 14: Rotation drive stop (therefore, the pressure roller 15 is also stopped)
-Power supply from the commercial power supply 4a to the heating element 2a; OFF-Auxiliary power supply device 4b; Rapid charging

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

It is a figure which shows the change of the roller temperature at the time of continuous paper passing in the conventional fixing device, and the remaining electric energy of an auxiliary power supply. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. 1 is a schematic diagram illustrating a configuration of a fixing device according to the present invention. It is a circuit diagram of a heating system in the fixing device according to the present invention. FIG. 5 is a diagram illustrating changes in roller temperature, power supplied to a heating unit, power discharged from a main power supply, and remaining power of an auxiliary power supply when continuous paper is passed through the fixing device according to the present invention. It is a figure which shows the change of the roller temperature in 1st Embodiment of the fixing device which concerns on this invention. It is a figure which shows the change of the roller temperature in the 2nd Embodiment of the fixing device which concerns on this invention, and the residual electric energy of an auxiliary power supply. It is a figure which shows the change of the residual electric energy of the auxiliary power supply in 3rd Embodiment of the fixing device which concerns on this invention. It is a figure which shows the example of a change of the roller temperature in 4th Embodiment of the fixing device which concerns on this invention. 1 is a circuit diagram of a heating system in a fixing device of the present invention that employs an electromagnetic induction heating means 1; FIG. FIG. 3 is a cross-sectional view showing a configuration of a fixing device of the present invention that employs an electromagnetic induction heating means 2. 1 is a perspective view showing a configuration of a fixing device of the present invention that employs an electromagnetic induction heating means 2; FIG. 2 is a cross-sectional view showing a configuration of a fixing device of the present invention that employs an electromagnetic induction heating means 3. FIG. 2 is a cross-sectional view showing a configuration of a fixing device of the present invention that employs electromagnetic induction heating means 4; FIG. FIG. 3 is a cross-sectional view illustrating a configuration of power supply in an image forming apparatus according to the present invention of a direct power feeding method. FIG. 3 is a cross-sectional view illustrating a configuration of power supply in the image forming apparatus according to the present invention of an indirect power feeding method.

2, 2a, 2b, 2a1, 2a2 Heating element 3 Second control unit 4a Commercial power supply (main power supply)
4b Auxiliary power supply device 5 Charging device 6 Main power switch 7 Charge / discharge switching device 8, 8a, 8b, 8c Temperature detection means 9 Main power supply device 10, 60 Fixing device 12a, 12b Induction heating coil 16a, 16b High frequency inverter 17a Rectifier circuit 17b DC / DC converter 14, 24, 34 Fixing roller 15 Pressure roller 21 Magnetic core 22 Inductive coil 23 Magnetic flux shielding plate 24a Core metal 24b Heat insulation layer 24c Heat generation layer 24d Elastic layer 24e Release layer 35 Thermopile 36 Thermistor 40 Control means 41 Photosensitive Body 42 Charging device 43 Mirror 44 Developing device 44a Developing roller 46 Cleaning device 46a Blade 47 Transfer unit 48 Transfer device 49 Registration roller 50 Induction heating inverter circuit 51 Plug 52 External heating means 54 Coil holder 56 Coil DESCRIPTION OF SYMBOLS 1 Fixing belt 62 Pressure belt 63 Fixing roller 63a Silicone rubber layer 63b Metal core 64 Fixing tension roller 64a Hollow roller 65 Heat pipe 66 Fixing pad 67 Pressing roller 68 Halogen heater 70 Pressing tension roller 71 Pressing pad 77 Pressing cross Member 78 Coil unit (magnetic flux generating means)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 System system 110 Paper feed roller 111 Paper discharge sensor 120 ADF (automatic document feeder)
DESCRIPTION OF SYMBOLS 130 Reader 140 Image forming part 150 Exposure part Lb Exposure light P Sheet (recording material)

Claims (8)

In an image forming apparatus including a fixing device and a power storage device,
The fixing device includes:
A rotating fixing member;
A pressure member that contacts the fixing member to form a nip portion;
Heating means for heating the fixing member,
The image forming apparatus includes:
When the temperature of the pressure member is lower than the threshold temperature after the last sheet of the plurality of sheets output in one printing request has exited the nip portion,
Start charging the power storage device,
Rotating the fixing member and the pressure member while heating the fixing member with electric power from an external power source ,
When the charging voltage of the power storage device exceeds a predetermined voltage from the start of charging of the power storage device,
An image forming apparatus, wherein rotation of the fixing member is stopped . After the last sheet exits the nip portion, when the temperature of the pressure member is equal to or higher than a threshold temperature,
The image forming apparatus includes:
Stop the rotation of the fixing member and the pressure member;
The image forming apparatus according to claim 1, wherein the power storage device is charged. The image forming apparatus according to claim 1 , wherein the predetermined voltage is a dischargeable voltage of the power storage device. The image forming apparatus includes:
After the last sheet exits the nip,
Wherein when heating the fixing member, wherein in any one of claims 1-3, characterized in that for controlling the temperature of the fixing member to a temperature higher than the temperature of the fixing member in output in the print request Image forming apparatus. The image forming apparatus includes:
After the last sheet exits the nip,
The image forming apparatus according to any one of claims 1-4, characterized in that to start the charging of the electric storage device while continuing rotation of the pressure member and the fixing member. The image forming apparatus includes:
The image forming apparatus according to any one of claims 1-5, characterized by supplying electric power of the electric storage device to the device other than the heating means. The image forming apparatus includes:
A reading device for reading an image and an automatic document feeder;
The image forming apparatus according to any one of claims 1-5, characterized by supplying electric power of the electric storage device to at least one of the reading device and the automatic document feeder. The image forming apparatus according to any one of claims 1 to 7 heat capacity of the pressure member, characterized in that greater than the heat capacity of the fixing member.