JP4646688B2 - Fixing apparatus, image forming apparatus, and heating control method of fixing apparatus - Google Patents

Description

  The present invention relates to a fixing device used in an image forming apparatus, an image forming apparatus such as a printer, a copying machine, and a facsimile machine using the fixing device, and a heating control method for a heater for the fixing device.

  In the fixing device of the image forming apparatus, in order to shorten the start-up time of the apparatus, it is necessary to shorten the time required to reach the fixable temperature when the fixing device is heated. For this reason, the first and second heating sources (heating heaters) and heating sources (pressure heaters) for heating the first rotating body (heating roller) and the second rotating body (pressure roller) respectively are heaters. It is necessary to increase the heat capacity. However, it is difficult to simply increase the heat capacity of the heater because of the increase in maximum power consumption and compliance with flicker regulations. For this reason, a plurality of fixing heaters are divided into heaters having a small capacity and a plurality of light distributions.

  Such a fixing device having a plurality of heaters is disclosed in, for example, Patent Document 1 or 2. As related inventions, the inventions described in Patent Documents 3 to 7 are also known.

  Among these, Patent Document 1 discloses an endless fixing belt for conveying a sheet-like medium on which toner is fixed, a heating roller and a fixing roller around which the fixing belt is wound, and the fixing via the fixing belt. A pressure roller disposed opposite the roller, a first temperature detection means for detecting the temperature of the heating roller, a second temperature detection means for detecting the temperature of the fixing roller, and In a fixing device having control means for controlling the temperature of the heating roller to become a set temperature based on a detection signal of the first temperature detection means, the set temperature of the heating roller is detected by the second temperature detection means. There is a set temperature determining means that determines based on the signal, and the temperature control is accurately controlled by performing temperature control corresponding to the temperature drop due to rotation of the fixing belt so that the fixing is good. There, the fixing property is disclosed an invention that aims to provide a fixing device of stabilized belt type.

Further, Patent Document 2 discloses a fixing roller positioned on the side facing a visible image on a transfer material formed based on a light image of the image obtained by illuminating an original image with an exposure unit, and the fixing roller. In the fixing device for fixing the visible image on the transfer material by passing the transfer material between the pressure roller and the pressure roller, a temperature sensor and a heater with different power consumption are disposed on each of the fixing roller and the pressure roller. These are controlled independently of each other, and the control temperature of the pressure roller, which is set lower than the set temperature of the heating roller, is higher during paper feeding than during standby, and the pressure roller temperature during paper feeding is higher. It is configured so that the heaters of the fixing roller and pressure roller are not turned on simultaneously when the temperature of the heating roller approaches and the exposure unit is in operation, and the temperature is controlled within a range where power consumption can be satisfied. So, a fixing device is disclosed in which to be able to fit into the standard power supply capacity and prescribed power consumption advance to prevent the fixing property with a decrease in temperature of the pressure roller.
JP 2003-156966 A Japanese Patent No. 3186906 Japanese Patent Laid-Open No. 09-016015 Japanese Patent Laid-Open No. 11-161095 JP 2001-056622 A JP 2003-307963 A JP 2004-045687 A

  However, in the fixing device having a plurality of heaters as described above, if all of the plurality of heaters are turned on at the same time, this is the same as an increase in the heat capacity of the heater. It becomes difficult to comply with regulations.

  The present invention has been made in view of such problems, and the object thereof is to turn on the maximum power as much as possible when the temperature of the fixing is raised, and to quickly shift to the temperature setting until copying is possible. There is in doing so.

In order to solve the above-mentioned object, the first means of the present invention fixes the image on the recording medium by passing the sheet-shaped recording medium between the first and second pair of rotating bodies. In the fixing device, a first heating source that heats the first rotating body, a first temperature detecting unit that detects a surface temperature of the first rotating body, and a first heat source that heats the second rotating body. Two heating sources, second temperature detecting means for detecting the surface temperature of the second rotating body, and the first and second temperatures based on the temperatures detected by the first and second temperature detecting means. Control means for controlling the heating amount of each of the heating sources, wherein the control means is a three-stage duty having a relationship of at least a first duty setting value> a second duty setting value> a third duty setting value. set different duty setting value ratio Wherein to control the heating amount of the first heat source, and the control in the first duty setting value when performing a set operation of a document to be subjected to optical scanning of a document image in the standby is not performed image forming Te, When continuous printing of a predetermined number of sheets or more is performed, after the start switch of the operation unit is pressed until the predetermined number of sheets are passed through the apparatus until the post-processing operation by the post-processing apparatus starts. Control with the second duty setting value, and after the passing of the paper to the apparatus is completed and the post-processing operation by the post-processing apparatus is started, the third power is set so that the total power becomes equal to or less than the device rating. Control is performed by a duty set value .

The image forming apparatus of the second means includes an input means for inputting image data, an image forming means for forming an image on a sheet-like recording medium based on the image data input from the input means, and the image forming The fixing device of the first means for fixing the image on the recording medium on which the image is formed by the means, and the recording medium on which the image is fixed by the fixing device are carried in, and a predetermined post-processing is performed as a post-processing operation. A post-processing device to be performed and an operation unit including a start switch are provided .

The third means is characterized in that , in the second means , the input means comprises an image reading device for optically scanning the original image and reading the image from the original .

Fourth means, in the third hand stage, the set operation of the document is characterized in that an operation to lift the pressing plate.

Fifth means, in the third hand stage, wherein the setting operation of the document is a document set to the automatic document feeding unit.

The sixth means is the heating control method of the fixing device for fixing the image on the recording medium by passing the sheet-like recording medium between the first and second pair of rotating bodies, and The first rotating body is heated by a first heating source, the surface temperature of the first rotating body is detected by first temperature detecting means, and the second rotating body is second heated. A second step of heating by a source and detecting a surface temperature of the second rotating body by a second temperature detector; and the temperature detected by the first and second temperature detectors. When controlling the heating amounts of the first and second heating sources, respectively, duty settings having different three-stage duty ratios of at least the first duty setting value> the second duty setting value> the third duty setting value are set. Set value A third step of controlling the heating amount of the first heating source, and in the third step, a document setting operation for optical scanning of the document image during standby without image formation. Is controlled by the first duty setting value, and when continuous printing of a predetermined number of sheets or more is performed, the passage of a predetermined number of sheets to the apparatus is completed after the start switch of the operation unit is pressed. Until the post-processing operation by the post-processing device is started, the second duty set value is used for control. After the paper is passed through the device, the post-processing operation by the post-processing device is started. Control is performed by the third duty setting value so that the total electric power is equal to or less than the device rating .

  In the following embodiments, the first rotating body is the fixing roller, the heating roller, and the fixing belt, the first heating source is the heaters 321 and 322, and the first temperature detection means is the first temperature detection sensor. 350, the second rotating body is the pressure roller 340, the second heating source is the pressure heater 341, the second temperature detection means is the second temperature detection sensor 351, and the control means is the control unit 601. The heat source is the first heater 321 and the second heater 322, the image forming unit is the image forming units 100 and 420, the image reading device is the reference numeral 500, the document pressure plate is the ADF 550, and the automatic document feeder is the document. Each corresponds to the mounting table 551.

According to the present invention, by controlling the heating amount of the first heat source and set the duty set value for at least three stages, Rutoki raises the surface temperature of the first rotating body, the power of the post-processing operation amount Even if necessary, after the end of the predetermined number of sheets on the fixing section where the post-processing operation starts when the continuous printing of a predetermined number of sheets or more is performed so that the total power does not exceed the device rating, Since the control is performed with the third duty setting value lower than the duty setting value of 2, the maximum power is applied as necessary when the temperature of the fixing is increased, and the temperature setting until copying becomes possible is quickly transferred. Can do.

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

<First Embodiment>
FIG. 1 is a diagram showing a schematic configuration of a color printer as a color image forming apparatus according to an embodiment of the present invention. In FIG. 1, the color printer basically includes an image forming unit 100, a paper feeding unit 200, a fixing unit (fixing device) 300, and a paper discharge unit 250.

  The image forming unit 100 includes CMYK photosensitive drums 101C, 101M, 101Y, and 101K, a writing unit for each color (not shown) that performs optical writing on the photosensitive drums 101C, 101M, 101Y, and 101K, and a photosensitive drum. Contact with the body drums 101C, 101M, 101Y, and 101K, and face each of the photosensitive drums 101C, 101M, 101Y, and 101K with the transfer belt 102 stretched between the driving pulley and the driven pulley and the transfer belt 102 interposed therebetween. The transfer roller 103C, 103M, 103Y, 103K provided at the position where the transfer is performed, and the transfer roller 104 provided downstream of the black transfer portion and sandwiching the vertical conveyance path 105 are mainly configured.

  The sheet feeding unit 200 conveys the first and second sheet feeding trays 210 and 220 and the transfer sheets 212 and 222 fed from the sheet feeding trays 210 and 220 by the sheet feeding rollers 211 and 221 to the longitudinal conveyance path 105. A transfer sheet conveyance path 106 for manual transfer, and a manual feed tray 230 for manually feeding the transfer sheet to the vertical conveyance path 105.

  The fixing device 300 is provided on the downstream side of the longitudinal conveyance path 105 in the transfer sheet conveyance direction, and includes a fixing roller 310, a heating roller 320, a fixing belt 330, and a pressure roller 340.

  The paper discharge unit 250 is provided downstream of the fixing device 300 in the transfer paper conveyance direction, and includes a paper discharge roller 410 and a paper discharge tray 420.

  In the color printer configured as described above, the transfer paper fed from the paper feed trays 210 and 220 or the manual feed tray 230 is sent out to the vertical conveyance path 105 and is formed by the image forming unit 100 that performs development and transfer. The full-color image superimposed on the surface of the transfer belt 102 is transferred onto the transfer paper by the transfer roller 104. The unfixed image transferred onto the transfer paper is sent to the fixing device 300 and is formed by a fixing roller 310 and a pressure roller 340 that are driven and driven inside the fixing belt 330 whose surface is heated by a heat source such as a heater. As a result, the sheet is fixed on the surface of the transfer paper and becomes a semi-permanent image, and is discharged to the discharge tray 420.

  FIG. 2 is a diagram showing a detailed configuration of the fixing device (fixing unit) 300. The fixing device 300 includes a fixing roller 310, a heating roller 320, and a fixing belt 330 stretched between them. The fixing roller 310 and the heating roller 320 are fixed, and a spring (pressing means or elastic biasing means) (not shown) is fixed. Appropriate tension is held by a belt tension member (tension roller) 331 under pressure. In addition, an appropriate pressure is applied between the fixing roller 310 and the pressure roller 320 which are located on the inner side of the fixing belt 330 and formed of an elastic body, and thereby, a nip is formed between the fixing belt 330 and the pressure roller 340. Is formed.

  First and second heaters 321 and 322 are provided inside the heating roller 320, and the heating roller 320 is heated from the inside by the heaters 321 and 322 to heat the fixing belt 330.

  There are two or more heaters 321 and 322, and they are controlled so that they may overlap each other when the paper is passed. Therefore, the heating is reduced while reducing the maximum power consumption and complying with the flicker regulations. Control of the heaters 321 and 322 can be made simple control independent of the state of each other.

  At least one of the plurality of heaters 321 and 322 is composed of a central heater having a light distribution characteristic in the central part, and at least one other is composed of an end heater having a light distribution characteristic in the end part. Since the plurality of heaters are used for heating, the maximum power consumption can be reduced and flicker regulations can be met.

  In this embodiment, the number of heaters 321 and 322 is two, but more may be used. Also, a temperature detection sensor 350 is provided on the outer peripheral portion of the heating roller 320 to detect the surface temperature of the fixing belt 330 in contact or non-contact, and the first heater is based on the detected surface temperature of the fixing belt 330. The energization of 321 is controlled to control the surface temperature of the fixing belt 330 to an appropriate temperature range. A heating heater (hereinafter referred to as a pressure heater) 341 is also provided inside the pressure roller 340, and the surface temperature of the pressure roller 340 is detected by a temperature detection sensor 351 provided on the outer periphery of the pressure roller 340. Then, the energization of the pressure heater 341 is controlled based on the detected surface temperature of the pressure roller 340, and the surface temperature of the pressure roller 340 is controlled within an appropriate temperature range. A cleaning member 360 is provided on the outer peripheral portion of the pressure roller 340 so as to clean dirt adhering to the surface of the pressure roller 340.

  In this embodiment, the fixing-side rotating body (fixing belt 330) side is the image surface side of the transfer paper P, and the pressure-side rotating body (pressure roller 340) side is the non-image side, and an unfixed image formed on the transfer paper 212 T1 is fixed on the transfer paper 212 while passing through the nip heated as described above. That is, the fixing toner image T2 adheres to the surface of the transfer paper 212 and is fixed.

  Reference numeral 371 denotes an inlet guide plate, 372 denotes a separating member, and 373 denotes an outlet guide plate.

  FIG. 3 is a block diagram illustrating a configuration of a control circuit of the image forming apparatus according to the present embodiment. The control circuit according to this embodiment includes a CPU 601, ROM 602, RAM 603, NV-RAM 604, operation unit 605, power transmission control unit 606, image memory 607, image processing unit 608, ADF document detection unit 609, and scanner pressure plate detection unit 610. . The CPU 601 includes a ROM 602 and a RAM 603, and controls the entire image forming apparatus by executing a program stored in the ROM 602 while using the RAM 603 as a work area. The NV-RAM 604 functions as a non-volatile memory for storing product data, and can replace the product data when replacing the PCB. Further, the NV-RAM 604 performs setting on the software by a method of storing the same data by dividing the inside into a plurality of areas.

  An operation unit 605 is used by an operator to perform operation input of the image forming apparatus according to the present embodiment. The electrical control unit 606 performs general I / F for mechanical control control of electrical components of the image forming apparatus. Further, the image memory 607 stores image information for image processing and image information after image processing, and stores image data to be processed by the image processing unit 608 and processed image data. In addition, an ADF document detection unit 609 and a scanner pressure plate open / close detection unit 610 are connected to the electrical control unit 606.

  FIG. 4 is a flowchart showing a processing procedure in the present embodiment, which is processed by the CPU 601 in FIG. 3 executing a program stored in the ROM 602. In this process, the ADF document detection (document detection by the document detection sensor of the ADF 600 in the second embodiment) timing or the scanner pressure plate opening / closing detection (opening / closing detection of the ADF 600 in the second embodiment) is not shown in this embodiment. From the timing until the start switch of the operation unit (not shown) of the image forming apparatus is pressed (steps S1 and S2), the fixing lighting duty is controlled at the setting 1 (for example, 100% is assumed) (heater is turned on) (step S3). This means that the presence of a document is detected in the ADF in steps S1 and S2 before the start switch is pressed, or that the opening / closing of the pressure plate is detected. This means that the document is set to be copied and will be copied from now on. It means that there is a copy operation request during standby.

Then, from the top Symbol start switch depressed until finisher (second corresponding to the post-processing apparatus in the embodiment) post-treatment operation such as is started (step S4), the on-duty as the power sum is below equipment rating Temperature rise control is performed with the second stage limit setting (setting 2) of 100% or less (step S5). After the end of sheet passing through the fixing section of the nth sheet (where n represents a predetermined number of natural numbers, as in the following) where post-processing operation of the finisher device or the like starts when continuous printing of a predetermined number of sheets or more is performed In (Step S6), the temperature rise control is performed with the third-stage limit setting (setting 3) with an on-duty of 100% or less so that the total power becomes equal to or less than the device rating (Steps S7 and S8). The set duty has a relationship (1) of first setting (first duty setting value) > second setting (second duty setting value) > third setting (third duty setting value) .

  As shown in FIG. 5, when the on-duty is 100%, the fixing lighting duty means that the fixing lighting duty is continuously turned on until the next control cycle comes. Duty control is executed by the CPU 601, and the on-duty is incremented by several%. change. That is, the CPU 601 sets on / off of the fixing heaters (first and second heaters 320 and 321) for each control cycle, but changes the on-duty within this on / off 1 cycle in increments of several percent. .

  In this embodiment, two heaters are provided as indicated by reference numerals 321 and 322. However, even when two or more heaters are used, the condition of the duty setting value of (1) is observed. The duty ratio may be set individually for each heater, or may be set in common.

  In the above embodiment, it is described that an image is formed on one side of the transfer paper 212 and the image is fixed. However, the same applies to the case where images are formed on both sides of each side. In this case, the image forming surface on the non-fixing side comes into contact with the pressure roller 340.

In the present embodiment, the heat capacity of the heating member is set such that the heat capacity of the heating member <the heat capacity of the pressure member. Here, the heating member corresponds to a member directly involved in heating, that is, the heating roller 320 and the fixing belt 330, and the pressure member corresponds to a member that applies pressure, that is, the pressure roller 340 and the fixing roller 310. . With this configuration, since the heat capacity on the pressure member side is large and the heat fluctuation is small, the fixing state can be controlled by heating control using a plurality of heat sources on the heating member side. Therefore, the pressure heater 341 which is a heating source on the heating member side. It is possible to sufficiently control the temperature of the fixing unit 300 without using a plurality of.

<Second Embodiment>
FIG. 6 is a schematic configuration diagram of the entire system showing an example of an image forming apparatus according to the second embodiment. In FIG. 1, an image forming apparatus is for monochrome image formation. A main body 400, an image reading apparatus 500 installed on the upper portion of the image forming apparatus main body 400, and an automatic document feeder (hereinafter referred to as an automatic document feeder) mounted thereon. , A large-capacity paper feeding device 700 disposed on the right side of the image forming apparatus main body 400 in FIG. 1, and a sheet post-processing apparatus disposed on the left side of the image forming apparatus main body 400 in FIG. 800 is basically composed.

  The image forming apparatus main body 400 includes an image writing unit 410, an image forming unit 420, a fixing unit 430, a duplex conveying unit 440, a paper feeding unit 450, a vertical conveying unit 460, and a manual feeding unit 470.

  The image writing unit 410 modulates the LD, which is a light source, based on the image information of the document read by the image reading device 500, and writes laser on the photosensitive drum 421 by a scanning optical system such as a polygon mirror and an fθ lens. is there. The image forming unit 420 includes a photosensitive drum 421 and known electrophotographic imaging elements such as a developing unit 422, a transfer unit 423, a cleaning unit 424, and a charge eliminating unit provided along the outer periphery of the photosensitive drum 421. Consists of.

  The fixing unit 430 fixes the image transferred by the transfer unit 423 on the transfer paper. The double-sided conveyance unit 440 is provided downstream of the fixing unit 420 in the transfer sheet conveyance direction, and includes a first switching claw 441 that switches the transfer sheet conveyance direction to the sheet post-processing device 800 side or the double-side conveyance unit 440 side, , The reverse conveying path 442 guided by the switching claw 441, the image forming side conveying path 443 that conveys the transfer paper reversed by the reverse conveying path 442 to the transfer unit 423 again, and the reverse transfer paper after the sheet post-processing device 800. A second switching claw 445 is disposed at a branch portion between the image forming side conveying path 443 and the post processing side conveying path 444.

  The sheet feeding unit 450 includes four sheet feeding stages, and the transfer sheets stored in the sheet feeding stages selected by the pickup roller and the sheet feeding roller are drawn out and guided to the vertical conveyance unit 460. The vertical conveyance unit 460 conveys the transfer paper fed from each paper feed stage to the registration roller 461 immediately upstream in the paper conveyance direction of the transfer unit 423, and the registration roller 461 provides a visible image on the photosensitive drum 421. The transfer paper is fed into the transfer unit 423 in time with the leading edge. The manual feed portion 470 includes an openable and closable manual feed tray 471, and opens the manual feed tray 471 as needed to supply transfer paper manually. Also in this case, the transfer timing of the transfer paper is taken by the registration roller 461 and is transported.

  The large-capacity paper feeding device 700 supplies a large amount of transfer paper of the same size, and the bottom plate 702 rises as the transfer paper is consumed, so that the paper can always be picked up from the pickup roller 701. ing. The transfer paper fed from the pickup roller 701 is conveyed from the vertical conveyance unit 460 to the nip of the registration roller 461.

  The sheet post-processing apparatus 800 performs predetermined processing such as punching, alignment, stapling, and sorting. In this embodiment, the punch 801, the staple tray (alignment) 802, the stapler 803, and the shift tray 804 are provided for the above functions. I have. In other words, the transfer paper carried from the image forming apparatus 400 to the paper post-processing apparatus 800 is punched one by one with the punch 801 when punching, and then if there is no particular processing, the proofing is performed. When sorting, stacking, and sorting to the tray 805, the sheets are discharged to the shift tray 804, respectively. In this embodiment, the sorting is performed by the reciprocating movement of the shift tray 804 by a predetermined amount in a direction orthogonal to the sheet conveyance direction. In addition, sorting can be performed by moving the paper in a direction orthogonal to the paper transport direction on the paper transport path.

  In the case of alignment, the transfer paper that has been punched or not punched is guided to the lower transport path 806, and the staple tray 804 is aligned in the direction perpendicular to the paper transport direction by the rear end fence. In the jogger fence, alignment in the direction parallel to the paper transport direction is performed. Here, when binding is performed, a predetermined position of the aligned sheet bundle, for example, a predetermined position such as a corner portion or two central positions is bound by the stapler 803 and discharged to the shift tray 804 by the discharge belt. In this embodiment, a pre-stack conveyance path 807 is provided in the lower conveyance path 806, and a plurality of sheets are stacked at the time of conveyance to avoid interruption of the image forming operation on the image forming apparatus main body 400 side during post-processing. Be able to.

  The image reading apparatus 500 is guided onto the contact glass 510 by the ADF 600, optically scans the stopped original, and reads the image formed by the imaging lens through the first to third mirrors, such as a CCD or CMOS. Read by the photoelectric conversion element. The read image data is subjected to predetermined image processing by an image processing circuit (not shown) and temporarily stored in a storage device. Then, it is read from the storage device by the image writing unit 410 during image formation, modulated according to the image data, and optical writing is performed.

  The ADF 550 has a double-sided reading function, and is attached to the contact glass 510 installation surface of the image reading device 500 so as to be freely opened and closed. In the ADF 550, the document placed on the document placement table 551 is automatically sent onto the contact glass 510 when the document is read.

  If the image forming unit 420 in this embodiment is replaced with the image forming unit 100 in the first embodiment and the paper feeding unit 450 is replaced with the paper feeding unit 200 in the first embodiment, an image reading device, an automatic document feeder, and A full-color copying apparatus including a post-processing apparatus can be configured. Further, when the document is placed on the contact glass 510 and read, the ADF 550 is opened with a hinge (not shown) on the rear side of the apparatus as a rotation center to expose the contact glass 510.

  In the image forming apparatus configured as described above, the document setting operation during standby when image formation by the seventh means is not performed is an operation of lifting the ADF 550 that also functions as a document pressure plate, or an automatic document feeder of the ADF 550. Corresponding to the operation of setting the document on the document table 551, when these operations are performed, the lighting control is performed with the on-duty in the first setting.

Other parts that are not particularly described are configured in the same manner as the first embodiment and function in the same manner.

As described above, according to the first and second embodiments,
1) When the document is detected by the ADF 550 during standby or when the pressure plate is opened or closed, it is determined that there is a copy operation request, and the maximum power is applied when the fixing temperature rises before the start switch is pressed. It is possible to shift quickly to the temperature setting possible.

2) Since the maximum possible power is supplied even when the temperature of the fixing nip portion is low after the copy start switch is pressed in the operation section and until the nth fixing section is passed, the recording paper is used. It is possible to prevent the occurrence of fixing failure due to a decrease in temperature due to heat deprived.

 3) Since the post-processing operation of the post-processing device 800 (finisher device, etc.) 800 after the completion of the n-th fixing unit passing, power for the post-processing operation of the post-processing device 800 or the like is required. Since the set value is limited so that the total electric power is less than or equal to the device rating, it is possible to prevent the total electric power from exceeding the device rating.

4) Since the power input amount is set to be large when the fixing nip temperature is low, fixing failure can be prevented and the total power can be prevented from exceeding the device rating.

5) Since at least one of the plurality of heaters 321 and 322 is divided into a central heater having a light distribution characteristic in the central part, and at least one is divided into an end heater having a light distribution characteristic in the end part. Maximum power consumption can be reduced, and compliance with flicker regulations can be achieved.

6) Since the heaters 321 and 322 are disposed in the heating roller 320 that rotates around the fixing belt 330, the structure of the heaters 321 and 322 can be simplified. Moreover, since it does not dissipate outside, thermal efficiency can be improved.

7) Since the pressure heater 341 that heats the pressure roller 340 heats the back side of the image on the recording medium, heat fixing can be performed efficiently.

8) Since the heat capacity of the heating member and the pressure member is set to the relationship of (heat capacity of the heating member) <(heat capacity of the pressure member), it is not necessary to use a plurality of pressure heaters, and the cost is low. be able to.

1 is a diagram illustrating a schematic configuration of a color printer as a color image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a detailed configuration of the fixing device illustrated in FIG. 1. FIG. 3 is a block diagram illustrating a portion related to the fixing device of the control circuit of the color printer according to the first exemplary embodiment of the present invention. It is a flowchart which shows the control procedure of the control performed in the 1st Embodiment of this invention. It is a timing chart which shows an example of the control timing of the control performed in the 1st embodiment of the present invention. It is a figure which shows the system configuration | structure of the image forming apparatus performed in the 2nd Embodiment of this invention.

Explanation of symbols

100, 420 Image forming unit 105, 460 Vertical conveyance path 200, 450 Paper feed unit 212 Transfer paper 250 Paper discharge unit 300, 430 Fixing device (unit)
310 fixing roller 320 heating roller 321, 322 heating heater 330 fixing belt 340 pressure roller 341 pressure heater 350 first temperature detection sensor 351 second temperature detection sensor 400 image forming apparatus main body 500 image reading apparatus 550 automatic document feeding Equipment (ADF)
600 Control circuit 601 CPU
800 Paper post-processing device

Claims (6)

In a fixing device for fixing an image on a recording medium by passing the sheet-shaped recording medium between a first and a second pair of rotating bodies,
A first heating source for heating the first rotary member, before Symbol a first temperature detecting means for detecting the surface temperature of the first rotary member, before Symbol second heating the second rotor heating source and, before Symbol second temperature sensing means and, before Symbol said first and second on the basis of the temperature detected by the first and second temperature detecting means for detecting the surface temperature of the second rotary member and control means for controlling the heating amount of the heating source, respectively,
Before SL control means, at least a first duty set value> second duty setting value> third of the first heat source duty ratio of 3 stages by setting different duty setting value becomes the duty set value relationship In addition to controlling the heating amount of the image, and when performing a document setting operation to be used for optical scanning of the document image during standby when image formation is not performed, the first duty setting value is used to perform continuous printing of a predetermined number of sheets or more. In this case, the second duty setting value is used until the predetermined number of sheets are passed through the apparatus after the start switch of the operation unit is pressed and the post-processing operation by the post-processing apparatus is started. And after the passing of the paper to the apparatus is completed and the post-processing operation by the post-processing apparatus is started, control is performed with the third duty setting value so that the total power becomes equal to or less than the device rating. A fixing device, characterized in that that. Input means for inputting image data, image forming means for forming an image on a sheet-like recording medium based on the image data input from the input means, and the recording medium on which an image is formed by the image forming means The fixing device according to claim 1, wherein the image is fixed thereon, a post-processing device that carries in a predetermined post-processing as a post-processing operation after a recording medium on which an image is fixed by the fixing device is carried in, and a start switch. And an operation unit. 3. The image forming apparatus according to claim 2, wherein the input unit includes an image reading device that optically scans the document image and reads the image from the document. 4. The image forming apparatus according to claim 3, wherein the document setting operation is an operation of lifting the document pressure plate. 4. The image forming apparatus according to claim 3, wherein the document setting operation is a document setting to an automatic document feeder. In a heating control method of a fixing device for fixing an image on a recording medium by passing a sheet-shaped recording medium between a first and a second pair of rotating bodies,
A first step of heating the first rotating body by a first heating source and detecting a surface temperature of the first rotating body by a first temperature detecting means;
A second step of heating the second rotating body by a second heating source and detecting a surface temperature of the second rotating body by a second temperature detecting means;
When controlling the heating amounts of the first and second heating sources based on the temperatures detected by the first and second temperature detectors, at least the first duty set value> the second duty set value > A third step of controlling the heating amount of the first heating source by setting a duty setting value having different three-stage duty ratios in relation to the third duty setting value,
In the third step, when a document setting operation for optical scanning of a document image is performed during standby when image formation is not performed, the first duty setting value is used to perform continuous printing of a predetermined number or more. In this case, after the start switch of the operation unit is pressed, the second duty setting value is controlled until the post-processing operation by the post-processing device is started after the predetermined number of sheets are passed through the device. Then, after the passing of the paper to the apparatus is completed and the post-processing operation by the post-processing apparatus is started, the control is performed with the third duty setting value so that the total electric power becomes equal to or less than the device rating. A heating control method for a fixing device.

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